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Find video protocols related to scientific articles indexed in Pubmed.
Measurement of the orbital angular momentum density of Bessel beams by projection into a Laguerre-Gaussian basis.
Appl Opt
PUBLISHED: 10-17-2014
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We present the measurement of the orbital angular momentum (OAM) density of Bessel beams and superpositions thereof by projection into a Laguerre-Gaussian basis. This projection is performed by an all-optical inner product measurement performed by correlation filters, from which the optical field can be retrieved in amplitude and phase. The derived OAM densities are compared to those obtained from previously stated azimuthal decomposition yielding consistent results.
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Bias due to selective inclusion and reporting of outcomes and analyses in systematic reviews of randomised trials of healthcare interventions.
Cochrane Database Syst Rev
PUBLISHED: 10-02-2014
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Systematic reviews may be compromised by selective inclusion and reporting of outcomes and analyses. Selective inclusion occurs when there are multiple effect estimates in a trial report that could be included in a particular meta-analysis (e.g. from multiple measurement scales and time points) and the choice of effect estimate to include in the meta-analysis is based on the results (e.g. statistical significance, magnitude or direction of effect). Selective reporting occurs when the reporting of a subset of outcomes and analyses in the systematic review is based on the results (e.g. a protocol-defined outcome is omitted from the published systematic review).
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A multicentre feasibility study evaluating stress ulcer prophylaxis using hospital-based registry data.
Crit Care Resusc
PUBLISHED: 08-28-2014
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It is unclear whether histamine-2 receptor blockers (H2RBs) or proton pump inhibitors (PPIs) are preferred for stress ulcer prophylaxis (SUP) in intensive care unit patients. Suitably powered comparative effectiveness trials are warranted.
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The safety of addition of nitrous oxide to general anaesthesia in at-risk patients having major non-cardiac surgery (ENIGMA-II): a randomised, single-blind trial.
Lancet
PUBLISHED: 08-22-2014
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Nitrous oxide is commonly used in general anaesthesia but concerns exist that it might increase perioperative cardiovascular risk. We aimed to gather evidence to establish whether nitrous oxide affects perioperative cardiovascular risk.
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Correcting for the bias caused by exposure measurement error in epidemiological studies.
Respirology
PUBLISHED: 08-14-2014
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An important goal of many epidemiological studies is to estimate the magnitude of association between an exposure and an outcome. Exposure measurement error causes bias in such estimates of association and can be substantial. In this article, we describe the problem of exposure measurement error and its effects. We show how a simple hand calculation, in conjunction with validation study data and a calibration equation, can be used to correct estimates for the bias caused by exposure measurement error. Correcting estimates of association for measurement error helps researchers appropriately assess effect size.
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The use of the cluster randomized crossover design in clinical trials: protocol for a systematic review.
Syst Rev
PUBLISHED: 08-12-2014
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The cluster randomized crossover (CRXO) design is gaining popularity in trial settings where individual randomization or parallel group cluster randomization is not feasible or practical. In a CRXO trial, not only are clusters of individuals rather than individuals themselves randomized to trial arms, but also each cluster participates in each arm of the trial at least once in separate periods of time.We will review publications of clinical trials undertaken in humans that have used the CRXO design. The aim of this systematic review is to summarize, as reported: the motivations for using the CRXO design, the values of the CRXO design parameters, the justification and methodology for the sample size calculations and analyses, and the quality of reporting the CRXO design aspects.
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Detection of Bessel beams with digital axicons.
Opt Express
PUBLISHED: 08-05-2014
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We propose a simple method for the detection of Bessel beams with arbitrary radial and azimuthal indices, and then demonstrate it in an all-digital setup with a spatial light modulator. We confirm that the fidelity of the detection method is very high, with modal cross-talk below 5%, even for high orbital angular momentum carrying fields with long propagation ranges. To illustrate the versatility of the approach we use it to observe the modal spectrum changes during the self-reconstruction process of Bessel beams after encountering an obstruction, as well as to characterize modal distortions of Bessel beams propagating through atmospheric turbulence.
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Simulating quantum state engineering in spontaneous parametric down-conversion using classical light.
Opt Express
PUBLISHED: 08-05-2014
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We present a simple method of simulating the effect of the pumping process in spontaneous parametric down-conversion (SPDC) by modulating a classical laser beam with two spatial light modulators through a back projection setup. We simulate a wide range of pump beams for quantum state engineering and confirm that the results are in agreement with theory. Our approach offers high photon count rates, is quick to yield results and can easily be converted back to a SPDC setup. It is likely to be a useful tool before starting more complicated SPDC experiments with custom pump profiles.
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All-digital wavefront sensing for structured light beams.
Opt Express
PUBLISHED: 06-13-2014
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We present a new all-digital technique to extract the wavefront of a structured light beam. Our method employs non-homogeneous polarization optics together with dynamic, digital holograms written to a spatial light modulator to measure the phase relationship between orthogonal polarization states in real-time, thereby accessing the wavefront information. Importantly, we show how this can be applied to measuring the wavefront of propagating light fields, over extended distances, without any moving components. We illustrate the versatility of the tool by measuring propagating optical vortices, Bessel, Airy and speckle fields. The comparison of the extracted and programmed wavefronts yields excellent agreement.
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White light wavefront control with a spatial light modulator.
Opt Express
PUBLISHED: 06-13-2014
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Spatial light modulators are ubiquitous tools for wavefront control and laser beam shaping but have traditionally been used with monochromatic sources due to the inherent wavelength dependence of the calibration process and subsequent phase manipulation. In this work we show that such devices can also be used to shape broadband sources without any wavelength dependence on the output beam's phase. We outline the principle mathematically and then demonstrate it experimentally using a supercontinuum source to shape rotating white-light Bessel beams carrying orbital angular momentum.
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Gamithromycin plasma and skin pharmacokinetics in sheep.
Res. Vet. Sci.
PUBLISHED: 05-23-2014
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This study assessed the plasma kinetics and skin/plasma concentration ratio of the azalide antibiotic gamithromycin (ZACTRAN(®), Merial) in sheep after a single subcutaneous administration at 6?mg/kg bodyweight. Gamithromycin concentrations in plasma samples collected at various intervals up to 21 days following treatment and metacarpal skin obtained from animals at two, five and ten days after treatment were determined by liquid chromatography-tandem mass spectrometry methods. After administration, gamithromycin was rapidly absorbed, and individual maximum plasma concentrations were observed within 6 hours post-dose. Plasma peak concentration was 573?±?168?ng/ml. The mean area under the plasma concentration versus time curve extrapolated to infinity was 8.00?±?1.41?µg?·?hr/ml, and the mean terminal half-life was 34.5?±?5.4 hours. Gamithromycin skin concentrations were much higher than the plasma concentrations resulting in skin/plasma concentration ratios of approximately 21, 58, and 138 at two, five and ten days post-dose, respectively, demonstrating extensive distribution to skin tissue.
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Parasite control practices on pasture-based dairy farms in the Republic of Ireland.
Vet. Parasitol.
PUBLISHED: 05-06-2014
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Dictyocaulus viviparus, Ostertagia ostertagi (nematode parasites), and Fasciola hepatica (trematode parasite) result in productivity losses on dairy farms and impact on animal health through clinical and sub-clinical disease. Parasite control in livestock systems is largely based on the use of chemoprophylactic agents (anthelmintics), grazing management, or a combination of both. The objective of this study was to document current parasite control measures employed by Irish dairy farmers in a predominantly pasture-based livestock system. A questionnaire survey of 312 geographically representative farmers was completed in 2009 with a follow up survey completed in 2011. Statistical analysis highlighted significant differences in chemoprophylactic usage between 2009 and 2011. In particular, an increase in the use of albendazole for both trematode (19% in 2009 to 36% in 2011) and nematode (30% in 2009 to 58% in 2011) control was observed. This was most likely due to flukicide restrictions introduced in the Republic of Ireland in 2010 for dairy animals. Logistic regression highlighted regional differences in chemoprophylactic use. Farmers in southern parts of Ireland, an area with good quality soil, less rainfall, and a higher density of dairy farms than other regions, were approximately half as likely to dose for F. hepatica and were more likely (OR>2.0) to use albendazole for both nematode and fluke control. Approximately 30% of respondents who used a chemoprophylactic treatment for nematodes, used a product which was 'unsuitable for purpose' (e.g. ivermectin for the treatment of F. hepatica), highlighting the need for increased awareness, continuing research, and regionally targeted education tools regarding optimal parasite control.
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Neuromuscular versus quadriceps strengthening exercise in patients with medial knee osteoarthritis and varus malalignment: a randomized controlled trial.
PUBLISHED: 04-24-2014
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To compare the effects of neuromuscular exercise (NEXA) and quadriceps strengthening (QS) on the knee adduction moment (an indicator of mediolateral distribution of knee load), pain, and physical function in patients with medial knee joint osteoarthritis (OA) and varus malalignment.
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Non-invasive indicators associated with the milk yield response after anthelmintic treatment at calving in dairy cows.
BMC Vet. Res.
PUBLISHED: 04-09-2014
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BackgroundGastrointestinal nematodes are an important cause of reduced performance in cattle. Previous studies in Europe showed that after anthelmintic treatment an average gain in milk production of around 1 kg per day/cow can be expected. However, (1) these studies have mainly evaluated group-based anthelmintic treatments during the grazing season or at housing and (2) little is known about parameters affecting variations in the treatment response amongst cows. A better knowledge of such parameters could help to select animals that benefit most from treatment and thus lead to a more rational use of anthelmintics. Therefore, a randomized, non-blinded, controlled clinical trial was performed on 11 commercial dairy farms (477 animals) in Belgium, aiming (1) to study the effect of eprinomectin treatment at calving on milk production and (2) to investigate whether the milk yield response was related to non-invasive animal parameters such that these could be used to inform targeted selective treatment decisions.ResultsAnalyses show that eprinomectin treatment around calving resulted in an average (± standard error) increase of 0.97 (±0.41) kg in daily milk yield that was followed up over 274 days on average. Milk yield responses were higher in multiparous compared to primiparous cows and in cows with a high (4th quartile) anti-O. ostertagi antibody level in a milk sample from the previous lactation. Nonetheless, high responses were also seen in animals with a low (1st quartile) anti-O. ostertagi antibody level. In addition, positive treatment responses were associated with higher faecal egg counts and a moderate body condition score at calving (2nd quartile).ConclusionsIn conclusion, this study provides novel insights into the production response after anthelmintic treatment at calving and factors which influence this. The data could be used to support the development of evidence-based targeted selective anthelmintic treatment strategies in dairy cattle.
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Introduction to propensity scores.
Respirology
PUBLISHED: 03-30-2014
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Although randomization provides a gold-standard method of assessing causal relationships, it is not always possible to randomly allocate exposures. Where exposures are not randomized, estimating exposure effects is complicated by confounding. The traditional approach to dealing with confounding is to adjust for measured confounding variables within a regression model for the outcome variable. An alternative approach--propensity scoring--instead fits a regression model to the exposure variable. For a binary exposure, the propensity score is the probability of being exposed, given the measured confounders. These scores can be estimated from the data, for example by fitting a logistic regression model for the exposure including the confounders as explanatory variables and obtaining the estimated propensity scores from the predicted exposure probabilities from this model. These estimated propensity scores can then be used in various ways-matching, stratification, covariate-adjustment or inverse-probability weighting-to obtain estimates of the exposure effect. In this paper, we provide an introduction to propensity score methodology and review its use within respiratory health research. We illustrate propensity score methods by investigating the research question: 'Does personal smoking affect the risk of subsequent asthma?' using data taken from the Tasmanian Longitudinal Health Study.
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Lethal interactions between parasites and prey increase niche diversity in a tropical community.
Science
PUBLISHED: 03-15-2014
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Ecological specialization should minimize niche overlap, yet herbivorous neotropical flies (Blepharoneura) and their lethal parasitic wasps (parasitoids) exhibit both extreme specialization and apparent niche overlap in host plants. From just two plant species at one site in Peru, we collected 3636 flowers yielding 1478 fly pupae representing 14 Blepharoneura fly species, 18 parasitoid species (14 Bellopius species), and parasitoid-host associations, all discovered through analysis of molecular data. Multiple sympatric species specialize on the same sex flowers of the same fly host-plant species-which suggests extreme niche overlap; however, niche partitioning was exposed by interactions between wasps and flies. Most Bellopius species emerged as adults from only one fly species, yet evidence from pupae (preadult emergence samples) show that most Bellopius also attacked additional fly species but never emerged as adults from those flies.
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Weight change and change in tibial cartilage volume and symptoms in obese adults.
Ann. Rheum. Dis.
PUBLISHED: 02-13-2014
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There is a paucity of data examining the effects of weight change on knee joint structures and symptoms. This study examined the effect of weight change on change in knee cartilage volume and symptoms in an obese cohort.
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Doughnut laser beam as an incoherent superposition of two petal beams.
Opt Lett
PUBLISHED: 02-04-2014
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Laguerre-Gaussian beams with a nonzero azimuthal index are known to carry orbital angular momentum (OAM), and are routinely created external to laser cavities. The few reports of obtaining such beams from laser cavities suffer from inconclusive evidence of the real electromagnetic field. In this Letter we revisit this question and show that an observed doughnut beam from a laser cavity may not be a pure Laguerre-Gaussian azimuthal mode but can be an incoherent sum of petal modes, which do not carry OAM. We point out the requirements for future analysis of such fields from laser resonators.
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Introduction to causal diagrams for confounder selection.
Respirology
PUBLISHED: 01-22-2014
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In respiratory health research, interest often lies in estimating the effect of an exposure on a health outcome. If randomization of the exposure of interest is not possible, estimating its effect is typically complicated by confounding bias. This can often be dealt with by controlling for the variables causing the confounding, if measured, in the statistical analysis. Common statistical methods used to achieve this include multivariable regression models adjusting for selected confounding variables or stratification on those variables. Therefore, a key question is which measured variables need to be controlled for in order to remove confounding. An approach to confounder-selection based on the use of causal diagrams (often called directed acyclic graphs) is discussed. A causal diagram is a visual representation of the causal relationships believed to exist between the variables of interest, including the exposure, outcome and potential confounding variables. After creating a causal diagram for the research question, an intuitive and easy-to-use set of rules can be applied, based on a foundation of rigorous mathematics, to decide which measured variables must be controlled for in the statistical analysis in order to remove confounding, to the extent that is possible using the available data. This approach is illustrated by constructing a causal diagram for the research question: 'Does personal smoking affect the risk of subsequent asthma?'. Using data taken from the Tasmanian Longitudinal Health Study, the statistical analysis suggested by the causal diagram approach was performed.
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Self-healing of quantum entanglement after an obstruction.
Nat Commun
PUBLISHED: 01-10-2014
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Quantum entanglement between photon pairs is fragile and can easily be masked by losses in transmission path and noise in the detection system. When observing the quantum entanglement between the spatial states of photon pairs produced by parametric down-conversion, the presence of an obstruction introduces losses that can mask the correlations associated with the entanglement. Here we show that we can overcome these losses by measuring in the Bessel basis, thus once again revealing the entanglement after propagation beyond the obstruction. We confirm that, for the entanglement of orbital angular momentum, measurement in the Bessel basis is more robust to these losses than measuring in the usually employed Laguerre-Gaussian basis. Our results show that appropriate choice of measurement basis can overcome some limitations of the transmission path, perhaps offering advantages in free-space quantum communication or quantum processing systems.
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Disease mapping and regression with count data in the presence of overdispersion and spatial autocorrelation: a Bayesian model averaging approach.
Int J Environ Res Public Health
PUBLISHED: 01-04-2014
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This paper applies the generalised linear model for modelling geographical variation to esophageal cancer incidence data in the Caspian region of Iran. The data have a complex and hierarchical structure that makes them suitable for hierarchical analysis using Bayesian techniques, but with care required to deal with problems arising from counts of events observed in small geographical areas when overdispersion and residual spatial autocorrelation are present. These considerations lead to nine regression models derived from using three probability distributions for count data: Poisson, generalised Poisson and negative binomial, and three different autocorrelation structures. We employ the framework of Bayesian variable selection and a Gibbs sampling based technique to identify significant cancer risk factors. The framework deals with situations where the number of possible models based on different combinations of candidate explanatory variables is large enough such that calculation of posterior probabilities for all models is difficult or infeasible. The evidence from applying the modelling methodology suggests that modelling strategies based on the use of generalised Poisson and negative binomial with spatial autocorrelation work well and provide a robust basis for inference.
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Urban land use decouples plant-herbivore-parasitoid interactions at multiple spatial scales.
PLoS ONE
PUBLISHED: 01-01-2014
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Intense urban and agricultural development alters habitats, increases fragmentation, and may decouple trophic interactions if plants or animals cannot disperse to needed resources. Specialist insects represent a substantial proportion of global biodiversity and their fidelity to discrete microhabitats provides a powerful framework for investigating organismal responses to human land use. We sampled site occupancy and densities for two plant-herbivore-parasitoid systems from 250 sites across a 360 km2 urban/agricultural landscape to ask whether and how human development decouples interactions between trophic levels. We compared patterns of site occupancy, host plant density, herbivory and parasitism rates of insects at two trophic levels with respect to landcover at multiple spatial scales. Geospatial analyses were used to identify landcover characters predictive of insect distributions. We found that herbivorous insect densities were decoupled from host tree densities in urban landcover types at several spatial scales. This effect was amplified for the third trophic level in one of the two insect systems: despite being abundant regionally, a parasitoid species was absent from all urban/suburban landcover even where its herbivore host was common. Our results indicate that human land use patterns limit distributions of specialist insects. Dispersal constraints associated with urban built development are specifically implicated as a limiting factor.
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Risk Factors for Community-Based Reports of Gastrointestinal, Respiratory, and Dermal Symptoms: Findings From a Cohort Study in Australia.
J Epidemiol
PUBLISHED: 11-16-2013
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Background: Although gastrointestinal (GI), respiratory, and dermal symptoms are common, few studies have conducted concurrent and comparative prospective analyses of risk factors for these 3 morbidity outcomes.Methods: We used data from a community-based randomized controlled trial among 277 South Australian families to analyze GI (diarrhea, vomiting), respiratory (sore throat, runny nose, cough) and dermal (rash, generalized itch, dermal infection) symptoms.Results: Log-binomial regression analysis revealed similar risks of GI (adjusted risk ratio [RR], 1.65; 95% CI, 1.05-2.58) and respiratory (RR, 1.68; 95% CI, 1.31-2.15) symptoms among childcare/kindergarten attendees. Swimming in public pools/spas in the current or previous week was associated with all 3 symptom complexes, conferring similar risk for each (RR for GI: 1.33; 95% CI, 0.99-1.77; respiratory: 1.20; 95% CI, 1.04-1.38; dermal: 1.41; 95% CI, 1.08-1.85). Pet ownership was not associated with symptoms. Household clustering of GI and respiratory symptoms was common, and clustering of respiratory symptoms correlated with number of individuals per household.Conclusions: This simultaneous examination of risk factors for 3 health outcomes yielded new comparative data that are useful for developing prevention strategies.
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Evaluating the impact of depression, anxiety & autonomic function on health related quality of life, vocational functioning and health care utilisation in acute coronary syndrome patients: the ADVENT study protocol.
BMC Cardiovasc Disord
PUBLISHED: 10-23-2013
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Depression and anxiety are highly prevalent and co-morbid in acute coronary syndrome patients. Somatic and cognitive subtypes of depression and anxiety in acute coronary syndrome have been shown to be associated with mortality although their association with patient outcomes is unknown, as are the mechanisms that underpin these associations. We are conducting a prospective cohort study which aims to examine in acute coronary syndrome patients: (1) the role of somatic subtypes of depression and anxiety as predictors of health related quality of life outcomes; (2) how somatic subtypes of depression and anxiety relate to long term vocational functioning and healthcare utilisation; and (3) the role of the autonomic nervous system assessed by heart rate variability as a moderator of these associations.
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Tuneable Gaussian to flat-top resonator by amplitude beam shaping.
Opt Express
PUBLISHED: 10-10-2013
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We outline a simple laser cavity comprising an opaque ring and a circular aperture that is capable of producing spatially tuneable laser modes, from a Gaussian beam to a Flat-top beam. The tuneability is achieved by varying the diameter of the aperture and thus requires no realignment of the cavity. We demonstrate this principle using a digital laser with an intra-cavity spatial light modulator, and confirm the predicted properties of the resonator experimentally.
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Generating and measuring nondiffracting vector Bessel beams.
Opt Lett
PUBLISHED: 08-31-2013
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Nondiffracting vector Bessel beams are of considerable interest due to their nondiffracting nature and unique high-numerical-aperture focusing properties. Here we demonstrate their creation by a simple procedure requiring only a spatial light modulator and an azimuthally varying birefringent plate, known as a q-plate. We extend our control of both the geometric and dynamic phases to perform a polarization and modal decomposition on the vector field. We study both single-charged Bessel beams as well as superpositions and find good agreement with theory. Since we are able to encode nondiffracting modes with circular polarizations possessing different orbital angular momenta, we suggest these modes will be of interest in optical trapping, microscopy, and optical communication.
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Angular self-reconstruction of petal-like beams.
Opt Lett
PUBLISHED: 08-31-2013
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The self-reconstruction of superpositions of Laguerre-Gaussian (LG) beams has been observed experimentally, but the results appear anomalous and without a means to predict under what conditions this take place. In this Letter, we offer a simple equation for predicting the self-reconstruction distance of superpositions of LG beams, which we confirm by numerical propagation as well as by experiment. We explain that the self-reconstruction process is not guaranteed and predict its dependence on the obstacle location and obstacle size.
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Telephone support to rural and remote patients with heart failure: the Chronic Heart Failure Assessment by Telephone (CHAT) study.
Cardiovasc Ther
PUBLISHED: 08-16-2013
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Heart failure (HF) remains a condition with high morbidity and mortality. We tested a telephone support strategy to reduce major events in rural and remote Australians with HF, who have limited healthcare access. Telephone support comprised an interactive telecommunication software tool (TeleWatch) with follow-up by trained cardiac nurses.
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Spatial properties of coaxial superposition of two coherent Gaussian beams.
Appl Opt
PUBLISHED: 08-14-2013
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In this paper, we explore theoretically and experimentally the laser beam shaping ability resulting from the coaxial superposition of two coherent Gaussian beams (GBs). This technique is classified under interferometric laser beam shaping techniques contrasting with the usual ones based on diffraction. The experimental setup does not involve the use of some two-wave interferometer but uses a spatial light modulator for the generation of the necessary interference term. This allows one to avoid the thermal drift occurring in interferometers and gives a total flexibility of the key parameter setting the beam transformation. In particular, we demonstrate the reshaping of a GB into a bottle beam or top-hat beam in the focal plane of a focusing lens.
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Variance reduction in randomised trials by inverse probability weighting using the propensity score.
Stat Med
PUBLISHED: 07-30-2013
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In individually randomised controlled trials, adjustment for baseline characteristics is often undertaken to increase precision of the treatment effect estimate. This is usually performed using covariate adjustment in outcome regression models. An alternative method of adjustment is to use inverse probability-of-treatment weighting (IPTW), on the basis of estimated propensity scores. We calculate the large-sample marginal variance of IPTW estimators of the mean difference for continuous outcomes, and risk difference, risk ratio or odds ratio for binary outcomes. We show that IPTW adjustment always increases the precision of the treatment effect estimate. For continuous outcomes, we demonstrate that the IPTW estimator has the same large-sample marginal variance as the standard analysis of covariance estimator. However, ignoring the estimation of the propensity score in the calculation of the variance leads to the erroneous conclusion that the IPTW treatment effect estimator has the same variance as an unadjusted estimator; thus, it is important to use a variance estimator that correctly takes into account the estimation of the propensity score. The IPTW approach has particular advantages when estimating risk differences or risk ratios. In this case, non-convergence of covariate-adjusted outcome regression models frequently occurs. Such problems can be circumvented by using the IPTW adjustment approach. © 2013 The authors. Statistics in Medicine published by John Wiley & Sons, Ltd.
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Reconstruction of laser beam wavefronts based on mode analysis.
Appl Opt
PUBLISHED: 07-23-2013
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We present the reconstruction of a laser beam wavefront from its mode spectrum and investigate in detail the impact of distinct aberrations on the mode composition. The measurement principle is presented on a Gaussian beam that is intentionally distorted by displaying defined aberrations on a spatial light modulator. The comparison of reconstructed and programmed wavefront aberrations yields excellent agreement, proving the high measurement fidelity.
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Serological evidence of Ostertagia ostertagi infection in dairy cows does not impact the efficacy of rabies vaccination during the housing period.
Res. Vet. Sci.
PUBLISHED: 06-14-2013
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Nematode infections modulate the immune reaction of humans and livestock and may impair immune responses to non-parasitic antigens such as those present in vaccines. In this study, the relationship between antibodies directed against Ostertagia ostertagi, the economically most important nematode infection of cattle in temperate regions, and the magnitude and the kinetics of the antibody response to rabies vaccination was investigated in a commercial dairy herd of 46 cows. During the stabling period, all animals received a single intramuscular administration with a commercial inactivated rabies vaccine (Rabisin®, Merial). The serum antibody levels against O. ostertagi on day 0 were compared with anti-rabies IgM, IgA, IgG1, IgG2 and virus-neutralizing antibodies on days 0, 7, 14 and 21 after vaccination. In addition, to explore the potential effect of newly acquired O. ostertagi infections, the kinetics of the O. ostertagi antibody levels during the first 2months after turnout on pasture were compared with concurrent changes in the rabies antibodies. During the stabling period the O. ostertagi antibody level tended to be positively associated with the magnitude, rate of increase and rate of decrease of the rabies antibodies. However, none of these associations were significant (P>0.05). Over the first 2months at pasture, an increase in O. ostertagi antibody level tended to be associated with a decrease in rabies IgG2 and IgM, but again these associations lacked statistical significance (P>0.20). We conclude that the O. ostertagi antibody level in adult cattle over the housing period has no significant association with the antibody response to rabies vaccination. We recommend that future studies aiming to assess the relationship of nematode infections with humoral immune responses to vaccines are conducted on a larger scale and focus on the summer period when cattle are exposed continuously to nematode challenge from the pasture and hence are actively responding immunologically to nematode antigen exposure.
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The longitudinal relationship between changes in body weight and changes in medial tibial cartilage, and pain among community-based adults with and without meniscal tears.
Ann. Rheum. Dis.
PUBLISHED: 06-06-2013
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INTRODUCTION: Meniscal tears are commonly found on MRI and increase the risk for radiographic knee osteoarthritis (OA). While meniscectomy is recommended when knee pain is severe or functionally disabling, it is unclear how to best treat meniscal tears without these symptoms. The aim of this longitudinal study was to examine the effect of weight change on knee cartilage and pain in a cohort of community-based adults with and without meniscal tears detected by MRI. METHODS: 250 adults with no history of knee OA or knee injury were recruited from the general community and weight-loss clinics. MRI of the knee, Western Ontario and McMaster University Osteoarthritis Index (WOMAC), weight and height were measured at baseline and again at follow-up approximately 2 years later. RESULTS: Medial meniscal tears were present in 36 (18%) of the cohort. In those with medial meniscal tears, after adjustment for confounders, percentage weight change was significantly associated with percentage change in medial tibial cartilage volume (? 0.2% 95% CI 0.08% to 0.3% p=0.002) and knee pain (? 11.6% 95% CI 2.1% to 21.1% p=0.02). That is, for every 1% gain in weight, there was an associated 0.2% increased loss of medial tibial cartilage volume and 11.6% increase in pain. In those with no medial meniscal tear, neither change in medial tibial cartilage volume (? 0.02% 95% CI -0.01% to 0.10% p=0.53) or pain (? 1.9% 95% CI -2.2% to 6.1% p=0.36) were significantly associated with change in weight. CONCLUSIONS: This study demonstrated that among adults with medial meniscal tears, weight gain is associated with increased cartilage loss and pain, while weight loss is associated with the converse. This suggests attention to weight is particularly important in the management of people with medial meniscal tears.
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The perception of injury risk and safety in triathlon competition: an exploratory focus group study.
Clin J Sport Med
PUBLISHED: 05-31-2013
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To explore stakeholder perceptions of triathlon competition safety and injury risk.
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A digital laser for on-demand laser modes.
Nat Commun
PUBLISHED: 05-30-2013
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Customizing the output beam shape from a laser invariably involves specialized optical elements in the form of apertures, diffractive optics and free-form mirrors. Such optics require considerable design and fabrication effort and suffer from the further disadvantage of being immutably connected to the selection of a particular spatial mode. Here we overcome these limitations with the first digital laser comprising an electrically addressed reflective phase-only spatial light modulator as an intra-cavity digitally addressed holographic mirror. The phase and amplitude of the holographic mirror may be controlled simply by writing a computer-generated hologram in the form of a grey-scale image to the device, for on-demand laser modes. We show that we can digitally control the laser modes with ease, and demonstrate real-time switching between spatial modes in an otherwise standard solid-state laser resonator. Our work opens new possibilities for the customizing of laser modes at source.
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Pain-related musculoskeletal disorders, psychological comorbidity and the relationship with physical and mental wellbeing in Gulf War veterans.
Pain
PUBLISHED: 04-30-2013
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Military veterans are at high risk of pain-related musculoskeletal disorders (MSD); Occupational activities such as lifting loads, working in constrained spaces, and training exertion in trainingincrease the risk of pain-related musculoskeletal disorders (MSD) in military veterans. Few studies have investigated MSD and psychological disorder in veterans; and previous studies had limitations. This cross-sectional study compared pain-related MSD and psychological disorder comorbidity and wellbeing between 1381456 male Australian 1990-1991 Gulf War veterans (veterans) and a military comparison group (n=1377588, of whom 39.6% were serving and 32.7% had previously deployed). At a medical assessment, 2000-20023, reported doctor diagnosed arthritis or rheumatism, back or neck problems, joint problems, and soft tissue disorders were rated by medical practitioners as non-medical, unlikely, possible or probable diagnoses. Only probable MSD were analysed. PPsychological disorders in the past 12 months were measured using the Composite International Diagnostic Interview. The Short-Form Health Survey (SF-12) assessed four-week physical and mental wellbeing. Almost one-quarter of veterans (24.5%) and comparison group (22.4%) reported a MSD. Having any or specific MSD were associated with depression and posttraumatic stress disorder (PTSD), but not alcohol disorders. Physical and mental wellbeing was poorer in those with a MSD compared to those without in both study groups (e.g. veterans with any MSD, difference in SF-12 PCS medians= -10.49: 95% CI -12.40,-8.57), and in those with MSD and psychological comorbidity compared with MSD alone(e.g. veterans with any MSD and depression or PTSD, difference in SF-12 MCS medians= -20.74: -24.3,-17.18). Patterns were similar in the comparison group. Comorbidity of any MSD and psychological disorder was more common in veterans, but MSD were associated with depression, PTSD and poorer wellbeing in both groups. Psychological comorbidity needs consideration in MSD management. Longitudinal studies are needed to assess directionality and causality.
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Exciting higher-order radial Laguerre-Gaussian modes in a diode-pumped solid-state laser resonator.
Appl Opt
PUBLISHED: 04-03-2013
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In this paper we experimentally demonstrate the intracavity generation of selected Laguerre-Gaussian modes of variable radial order, from 0 to 5. Our technique requires only an amplitude mask made up of absorbing rings to be placed inside the cavity, with the ring radii selected to coincide with the zeros of the desired Laguerre-Gaussian mode. We demonstrate high mode purity and a mode volume proportional to the order of the mode. Our results suggest a possible route to high brightness diode-pumped solid-state laser sources.
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Association of weight gain with incident knee pain, stiffness, and functional difficulties: a longitudinal study.
Arthritis Care Res (Hoboken)
PUBLISHED: 03-15-2013
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To examine the longitudinal association between significant weight change and change in knee symptoms (pain, stiffness, and function), and to determine whether the effects differ in those who are obese and those with osteoarthritis (OA).
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Estimating the effect of long-term physical activity on cardiovascular disease and mortality: evidence from the Framingham Heart Study.
Heart
PUBLISHED: 03-08-2013
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In the majority of studies, the effect of physical activity (PA) on cardiovascular disease (CVD) and mortality is estimated at a single time point. The impact of long-term PA is likely to differ. Our study objective was to estimate the effect of long-term adult-life PA compared with long-term inactivity on the risk of incident CVD, all-cause mortality and CVD-attributable mortality.
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Efficient sorting of Bessel beams.
Opt Express
PUBLISHED: 02-08-2013
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We demonstrate the efficient sorter of Bessel beams separating both the azimuthal and radial components. This is based upon the recently reported transformation of angular to transverse momentum states. We separately identify over forty azimuthal and radial components, with a radial spacing of 1588 m(-1), and outline how the device could be used to identify the two spatial dimensions simultaneously.
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Are psychosocial factors associated with low back pain and work absence for low back pain in an occupational cohort?
Clin J Pain
PUBLISHED: 02-02-2013
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To examine the relationship between individual and work-related psychosocial factors and low back pain (LBP) and associated time off work in an occupational cohort.
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Modelling the short- and long-term impacts of drenching frequency and targeted selective treatment on the performance of grazing lambs and the emergence of anthelmintic resistance.
Parasitology
PUBLISHED: 02-01-2013
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Refugia-based treatment strategies aim to prolong anthelmintic efficacy by maintaining a parasite population unexposed to anthelmintics. Targeted selective treatment (TST) achieves this by treating only animals that will benefit most from treatment, using a determinant criterion (DC). We developed a mathematical model to compare various traits proposed as DC, and investigate impacts of TST and drenching frequency on sheep performance and anthelmintic resistance. Short term, decreasing the proportion of animals drenched reduced benefits of anthelmintic treatment, assessed by empty body weight (EBW), but decreased the rate of anthelmintic resistance development; each consecutive drenching had a reduced impact on average EBW and an increased impact on the rate of anthelmintic resistance emergences. The optimal DC was fecal egg count, maintaining the highest average EBW when reducing the proportion of animals drenched. Long-term, reducing the proportion of animals drenched had little impact on total weight gain benefits, across animals and years, whilst reducing drenching frequency increased it. Decreasing the frequency and proportion of animals drenched were both predicted to increase the duration of anthelmintic efficacy but reduce the total number of drenches administered before resistance was observed. TST and frequency of drenching may lead to different benefits in the short versus long term.
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Implementing quantum walks using orbital angular momentum of classical light.
Phys. Rev. Lett.
PUBLISHED: 01-30-2013
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We present an implementation scheme for a quantum walk in the orbital angular momentum space of a laser beam. The scheme makes use of a ring interferometer, containing a quarter-wave plate and a q plate. This setup enables one to perform an arbitrary number of quantum walk steps. In addition, the classical nature of the implementation scheme makes it possible to observe the quantum walk evolution in real time. We use nonquantum entanglement of the laser beams polarization with its orbital angular momentum to implement the quantum walk.
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Nitrous oxide and serious morbidity and mortality in the POISE trial.
Anesth. Analg.
PUBLISHED: 01-21-2013
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In this post hoc subanalysis of the Perioperative Ischemic Evaluation (POISE) trial, we sought to determine whether nitrous oxide was associated with the primary composite outcome of cardiovascular death, nonfatal myocardial infarction (MI), and nonfatal cardiac arrest within 30 days of randomization.
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Temporal mood changes associated with different levels of adolescent drinking: using mobile phones and experience sampling methods to explore motivations for adolescent alcohol use.
Drug Alcohol Rev
PUBLISHED: 01-19-2013
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Alcohol use during adolescence is associated with the onset of alcohol use disorders, mental health disorders, substance abuse as well as socially and physically damaging behaviours, the effects of which last well into adulthood. Nevertheless, alcohol use remains prevalent in this population. Understanding motivations behind adolescent alcohol consumption may help in developing more appropriate and effective interventions. This study aims to increase this understanding by exploring the temporal relationship between mood and different levels of alcohol intake in a sample of young people.
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Many scenarios exist for selective inclusion and reporting of results in randomized trials and systematic reviews.
J Clin Epidemiol
PUBLISHED: 01-18-2013
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To collate and categorize the ways in which selective inclusion and reporting can occur in randomized controlled trials (RCTs) and systematic reviews.
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Focusing light with a flame lens.
Nat Commun
PUBLISHED: 01-16-2013
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The lens is a well-understood optical component used for focusing light, but is almost exclusively made in the solid-state form and, thus, suffers from optical damage at high powers. Attempts to overcome this through the use of non-solid graded-index media for lensing, for example, heated gasses, have found limited application owing to their long focal lengths. Here we describe the first flame lens, which produces a sharp focus with very little stray light and has a fourfold increase in focal power per unit length over previous gas lenses. Such gas devices remain topical due to their inherent ability to deliver high-power laser beams: our flame lens has a damage threshold that is several orders of magnitude higher than that of most conventional lenses and is immediately repaired after damage for reuse, and thus will be of use in focusing high-irradiance laser beams.
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An empirical investigation of the potential impact of selective inclusion of results in systematic reviews of interventions: study protocol.
Syst Rev
PUBLISHED: 01-09-2013
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Systematic reviewers may encounter a multiplicity of outcome data in the reports of randomised controlled trials included in the review (for example, multiple measurement instruments measuring the same outcome, multiple time points, and final and change from baseline values). The primary objectives of this study are to investigate in a cohort of systematic reviews of randomised controlled trials of interventions for rheumatoid arthritis, osteoarthritis, depressive disorders and anxiety disorders: (i) how often there is multiplicity of outcome data in trial reports; (ii) the association between selection of trial outcome data included in a meta-analysis and the magnitude and statistical significance of the trial result, and; (iii) the impact of the selection of outcome data on meta-analytic results.
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Lungworm Infections in German dairy cattle herds--seroprevalence and GIS-supported risk factor analysis.
PLoS ONE
PUBLISHED: 01-01-2013
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In November 2008, a total of 19,910 bulk tank milk (BTM) samples were obtained from dairy farms from all over Germany, corresponding to about 20% of all German dairy herds, and analysed for antibodies against the bovine lungworm Dictyocaulus viviparus by use of the recombinant MSP-ELISA. A total number of 3,397 (17.1%; n = 19,910) BTM samples tested seropositive. The prevalences in individual German federal states varied between 0.0% and 31.2% positive herds. A geospatial map was drawn to show the distribution of seropositive and seronegative herds per postal code area. ELISA results were further analysed for associations with land-use and climate data. Bivariate statistical analysis was used to identify potential spatial risk factors for dictyocaulosis. Statistically significant positive associations were found between lungworm seropositive herds and the proportion of water bodies and grassed area per postal code area. Variables that showed a statistically significant association with a positive BTM test were included in a logistic regression model, which was further refined by controlled stepwise selection of variables. The low Pseudo R(2) values (0.08 for the full model and 0.06 for the final model) and further evaluation of the model by ROC analysis indicate that additional, unrecorded factors (e.g. management factors) or random effects may substantially contribute to lungworm infections in dairy cows. Veterinarians should include lungworms in the differential diagnosis of respiratory disease in dairy cattle, particularly those at pasture. Monitoring of herds through BTM screening for antibodies can help farmers and veterinarians plan and implement appropriate control measures.
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Comparison of neuromuscular and quadriceps strengthening exercise in the treatment of varus malaligned knees with medial knee osteoarthritis: a randomised controlled trial protocol.
BMC Musculoskelet Disord
PUBLISHED: 11-15-2011
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Osteoarthritis of the knee involving predominantly the medial tibiofemoral compartment is common in older people, giving rise to pain and loss of function. Many people experience progressive worsening of the disease over time, particularly those with varus malalignment and increased medial knee joint load. Therefore, interventions that can reduce excessive medial knee loading may be beneficial in reducing the risk of structural progression. Traditional quadriceps strengthening can improve pain and function in people with knee osteoarthritis but does not appear to reduce medial knee load. A neuromuscular exercise program, emphasising optimal alignment of the trunk and lower limb joints relative to one another, as well as quality of movement performance, while dynamically and functionally strengthening the lower limb muscles, may be able to reduce medial knee load. Such a program may also be superior to traditional quadriceps strengthening with respect to improved pain and physical function because of the functional and dynamic nature. This randomised controlled trial will investigate the effect of a neuromuscular exercise program on medial knee joint loading, pain and function in individuals with medial knee joint osteoarthritis. We hypothesise that the neuromuscular program will reduce medial knee load as well as pain and functional limitations to a greater extent than a traditional quadriceps strengthening program.
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Short- and long-term outcomes of intracoronary and endogenously mobilized bone marrow stem cells in the treatment of ST-segment elevation myocardial infarction: a meta-analysis of randomized control trials.
Eur. J. Heart Fail.
PUBLISHED: 11-06-2011
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Bone marrow stem cell (BMSC) treatment of ST-segment elevation myocardial infarction (STEMI) has been primarily via the intracoronary route or via endogenous mobilization using granulocyte colony-stimulating factor (G-CSF). Studies have provided conflicting results. We therefore performed a meta-analysis of these treatments, examining short- and long-term efficacy and safety.
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Poynting vector and orbital angular momentum density of superpositions of Bessel beams.
Opt Express
PUBLISHED: 09-22-2011
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We study theoretically the orbital angular momentum (OAM) density in arbitrary scalar optical fields, and outline a simple approach using only a spatial light modulator to measure this density. We demonstrate the theory in the laboratory by creating superpositions of non-diffracting Bessel beams with digital holograms, and find that the OAM distribution in the superposition field matches the predicted values. Knowledge of the OAM distribution has relevance in optical trapping and tweezing, and quantum information processing.
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A survey on Dictyocaulus viviparus antibodies in bulk milk of dairy herds in Northern Germany.
Prev. Vet. Med.
PUBLISHED: 07-18-2011
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Parasitic bronchitis caused by the bovine lungworm, Dictyocaulus viviparus, occurs worldwide in temperate areas. The parasite is found predominantly in calves and heifers, but dairy cattle can suffer from lungworms when they become infected for the first time or if they have lost immunity due to lack of exposure to lungworm larvae during the grazing season. The present study was performed to determine the D. viviparus bulk milk antibody prevalence in dairy herds in the East Frisian region of northwestern Germany, Lower Saxony, by analysing bulk milk samples collected in January (860 samples), September (866 samples) and November (860 samples) 2008, thereby representing 906 dairy farms. These samples were tested for antibodies against D. viviparus by a milk ELISA. This test detects patent infections only since it is based on recombinant major sperm protein as antigen. While in January 12.8% of dairy farms were positive for D. viviparus antibodies, the bulk milk samples collected in September and November revealed 6.9% and 6.6% positive dairy herds. From the 906 dairy farms included in the study, 191 (21.1%) tested positive at least once for antibodies against lungworm. From 810 dairy farms from which bulk milk samples were obtained during all three samplings, 146 (18.0%) farms were positive at one sampling date, 27 (3.3%) at two, and 4 (0.5%) on all three sampling dates. The majority of the farms represented in the study belonged to four districts of East Frisia, which showed no significant difference in the proportion of positive dairy farms.
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Mean focal length of an aberrated lens.
J Opt Soc Am A Opt Image Sci Vis
PUBLISHED: 07-08-2011
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We outline an approach for the calculation of the mean focal length of an aberrated lens and provide closed-form solutions that show that the focal length of the lens is dependent on the presence of defocus, x-astigmatism, and spherical aberration. The results are applicable to Gaussian beams in the presence of arbitrary-sized apertures. The theoretical results are confirmed experimentally, showing excellent agreement. As the final results are in algebraic form, the theory may readily be applied in the laboratory if the aberration coefficients of the lens are known.
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Generalized beam quality factor of aberrated truncated Gaussian laser beams.
J Opt Soc Am A Opt Image Sci Vis
PUBLISHED: 07-08-2011
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We outline a theory for the calculation of the beam quality factor of an aberrated laser beam. We provide closed-form equations that show that the beam quality factor of an aberrated Gaussian beam depends on all primary aberrations except tilt, defocus, and x-astigmatism. The model is verified experimentally by implementing aberrations as digital holograms in the laboratory.
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Lateral wedge insoles for medial knee osteoarthritis: 12 month randomised controlled trial.
BMJ
PUBLISHED: 05-20-2011
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To assess the effect of lateral wedge insoles compared with flat control insoles on improving symptoms and slowing structural disease progression in medial knee osteoarthritis.
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Predicting future depression in adolescents using the Short Mood and Feelings Questionnaire: a two-nation study.
J Affect Disord
PUBLISHED: 05-13-2011
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Adolescence is a key life period for the development of depression. Predicting the development of depression in adolescence through detecting specific early symptoms may aid in the development of timely screening and intervention programmes.
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Ecoinformatics for integrated pest management: expanding the applied insect ecologists tool-kit.
J. Econ. Entomol.
PUBLISHED: 04-23-2011
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Experimentation has been the cornerstone of much of integrated pest management (IPM) research. Here, we aim to open a discussion on the possible merits of expanding the use of observational studies, and in particular the use of data from farmers or private pest management consultants in "ecoinformatics" studies, as tools that might complement traditional, experimental research. The manifold advantages of experimentation are widely appreciated: experiments provide definitive inferences regarding causal relationships between key variables, can produce uniform and high-quality data sets, and are highly flexible in the treatments that can be evaluated. Perhaps less widely considered, however, are the possible disadvantages of experimental research. Using the yield-impact study to focus the discussion, we address some reasons why observational or ecoinformatics approaches might be attractive as complements to experimentation. A survey of the literature suggests that many contemporary yield-impact studies lack sufficient statistical power to resolve the small, but economically important, effects on crop yield that shape pest management decision-making by farmers. Ecoinformatics-based data sets can be substantially larger than experimental data sets and therefore hold out the promise of enhanced power. Ecoinformatics approaches also address problems at the spatial and temporal scales at which farming is conducted, can achieve higher levels of "external validity," and can allow researchers to efficiently screen many variables during the initial, exploratory phases of research projects. Experimental, observational, and ecoinformatics-based approaches may, if used together, provide more efficient solutions to problems in pest management than can any single approach, used in isolation.
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Posttraumatic stress disorder and hypertension in Australian veterans of the 1991 Gulf War.
J Psychosom Res
PUBLISHED: 04-18-2011
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Military veterans experience a high prevalence of psychopathologies such as posttraumatic stress disorder (PTSD). Relationships between physical and psychological health are increasingly recognised. This study investigated associations between PTSD and hypertension in male Australian Gulf War veterans.
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Use of fluorescent lectin binding to distinguish Teladorsagia circumcincta and Haemonchus contortus eggs, third-stage larvae and adult worms.
Parasitol. Res.
PUBLISHED: 04-06-2011
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Lectin binding to carbohydrates on parasite surfaces has been investigated as a method of distinguishing adult worms, eggs and sheathed and exsheathed L3 of Teladorsagia circumcincta and Haemonchus contortus, economically important abomasal parasites in temperate climates. Both species were maintained as pure laboratory cultures of field isolates from New Zealand. Each of the four life cycle stages could be distinguished by the binding of at least one lectin: adult worms by Sambucus nigra agglutinin (SNA); eggs by peanut agglutinin (PNA), ConcavalinA and Lens culinaris agglutinin (LCA); exsheathed L3 by Griffonia simplicifolia-I lectin (GSL-I) and Lotus tetragonolobus lectin (LTL) and sheathed L3 by Aleuria aurantia lectin (AAL). The whole surface of both adult T. circumcincta and H. contortus strongly bound lectins specific for N-acetylglucosamine (GlcNAc), N-acetylgalactosamine (GalNAc), mannose and fucose, but the two species could be distinguished by SNA binding only to T. circumcincta. Eggs could be distinguished by the binding of mannose-specific PNA to H. contortus and GalNAc-specific LCA and PSA to T. circumcincta eggs. GalNAc, GlcNAc and mannose lectins bound to the cuticle and over the excretory pores of a large proportion of sheathed L3 of both species, but only the H. contortus surface had exposed fucose or sialic acid complexes. The distinguishing lectin for sheathed L3 was AAL, which did not bind to T. circumcincta, but bound weakly to the head region of all fresh H. contortus and to 50-90% after 3 months storage. The cuticle of exsheathed L3 was unresponsive to all 19 lectins, and any binding was restricted to the head and tail regions. L3 exsheathed after 2-4 months storage could be distinguished by the binding of GSL-I and LTL to H. contortus but not to T. circumcincta. Lectin binding could be a useful adjunct in identifying L3, but lacked the consistency to be definitive, whereas it could be further developed as a practical method of distinguishing parasitic nematodes at other stages in the life cycle, particularly the eggs.
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Comparing the responsiveness of functional outcome assessment measures for trauma registries.
J Trauma
PUBLISHED: 03-24-2011
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Measuring long-term disability and functional outcomes after major trauma is not standardized across trauma registries. An ideal measure would be responsive to change but not have significant ceiling effects. The aim of this study was to compare the responsiveness of the Glasgow Outcome Scale (GOS), GOS-Extended (GOSE), Functional Independence Measure (FIM), and modified FIM in major trauma patients, with and without significant head injuries.
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Formation of tungsten oxide nanostructures by laser pyrolysis: stars, fibres and spheres.
Nanoscale Res Lett
PUBLISHED: 02-23-2011
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In this letter, the production of multi-phase WO3 and WO3-x (where x could vary between 0.1 and 0.3) nanostructures synthesized by CO2-laser pyrolysis technique at varying laser wavelengths (9.22-10.82 mm) and power densities (17-110 W/cm2) is reported. The average spherical particle sizes for the wavelength variation samples ranged between 113 and 560 nm, and the average spherical particle sizes for power density variation samples ranged between 108 and 205 nm. Synthesis of W18O49 (= WO2.72) stars by this method is reported for the first time at a power density and wavelength of 2.2 kW/cm2 and 10.6 ?m, respectively. It was found that more concentrated starting precursors result in the growth of hierarchical structures such as stars, whereas dilute starting precursors result in the growth of simpler structures such as wires.
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The spatial distribution of esophageal and gastric cancer in Caspian region of Iran: an ecological analysis of diet and socio-economic influences.
Int J Health Geogr
PUBLISHED: 02-15-2011
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Recent studies have suggested a systematic geographic pattern of esophageal cancer (EC) and gastric cancer (GC) incidence in the Caspian region of Iran. The aims of this study were to investigate the association between these cancers and the regions dietary and socioeconomic risk factors and to map EC and GC after adjustment for the risk factors and the removal of random and geographic variations from area specific age standardised incidence ratios (SIRs). We obtained cancer data from the Babol cancer registry from 2001 to 2005, socioeconomic indices from the Statistical Centre of Iran, and dietary patterns from the control group in a case control study conducted in the study region. Regression models were fitted to identify significant covariates, and clusters of elevated rates were identified. We found evidence of systematic clustering for EC and GC in men and women and both sexes combined. EC and GC SIRs were lower in urban areas, and were also lower in areas of high income. EC SIRs were lower in areas with higher proportions of people having unrestricted food choice and higher in areas with higher proportions of people with restricted food choice. EC and GC were associated with aggregated risk factors, including income, urbanisation, and dietary patterns. These variables represent the influence of improved lifestyle which has coincided with a decrease in upper gastrointestinal cancer frequency over recent decades but which has not necessarily been uniform throughout the region.
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A randomised, feasibility trial of a tele-health intervention for acute coronary syndrome patients with depression (MoodCare): study protocol.
BMC Cardiovasc Disord
PUBLISHED: 02-04-2011
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Coronary heart disease (CHD) and depression are leading causes of disease burden globally and the two often co-exist. Depression is common after Myocardial Infarction (MI) and it has been estimated that 15-35% of patients experience depressive symptoms. Co-morbid depression can impair health related quality of life (HRQOL), decrease medication adherence and appropriate utilisation of health services, lead to increased morbidity and suicide risk, and is associated with poorer CHD risk factor profiles and reduced survival. We aim to determine the feasibility of conducting a randomised, multi-centre trial designed to compare a tele-health program (MoodCare) for depression and CHD secondary prevention, with Usual Care (UC).
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When should one adjust for measurement error in baseline variables in observational studies?
Biom J
PUBLISHED: 01-14-2011
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Previously, we showed that in randomised experiments, correction for measurement error in a baseline variable induces bias in the estimated treatment effect, and conversely that ignoring measurement error avoids bias. In observational studies, non-zero baseline covariate differences between treatment groups may be anticipated. Using a graphical approach, we argue intuitively that if baseline differences are large, failing to correct for measurement error leads to a biased estimate of the treatment effect. In contrast, correction eliminates bias if the true and observed baseline differences are equal. If this equality is not satisfied, the corrected estimator is also biased, but typically less so than the uncorrected estimator. Contrasting these findings, we conclude that there must be a threshold for the true baseline difference, above which correction is worthwhile. We derive expressions for the bias of the corrected and uncorrected estimators, as functions of the correlation of the baseline variable with the study outcome, its reliability, the true baseline difference, and the sample sizes. Comparison of these expressions defines a theoretical decision threshold about whether to correct for measurement error. The results show that correction is usually preferred in large studies, and also in small studies with moderate baseline differences. If the group sample sizes are very disparate, correction is less advantageous. If the equivalent balanced sample size is less than about 25 per group, one should correct for measurement error if the true baseline difference is expected to exceed 0.2-0.3 standard deviation units. These results are illustrated with data from a cohort study of atherosclerosis.
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Confounder-adjusted estimates of the risk difference using propensity score-based weighting.
Stat Med
PUBLISHED: 12-21-2010
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Confounder-adjusted estimates of the risk difference are often difficult to obtain by direct regression adjustment. Estimates can be obtained from a propensity score-based method using inverse probability-of-exposure weights to balance groups defined by exposure status with respect to confounders. Simulation was used to evaluate the performance of this method. The simulation model incorporated a binary confounder and a normally distributed confounder into logistic models of exposure status, and disease status conditional on exposure status. Data were generated for combinations of values of several design parameters, including the odds ratio relating each of the confounders to exposure status, the odds ratio relating each of the confounders to disease status and the total sample size. For most design parameter combinations (474 of 486), the absolute bias in the estimated risk difference was less than 1 percentage point, and it was never greater than 3 percentage points. The confidence interval generally had close to nominal 95 per cent coverage, but was prone to poor coverage levels (as low as 78.5 per cent) when both the confounder-to-exposure and confounder-to-outcome odds ratios were 5, consistent with strong confounding. The simulation results showed that the conditions that are favourable for good performance of the weighting method are: reasonable overlap in the propensity score distributions of the exposed and non-exposed groups and a large sample size.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.