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October, 2006
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Tree Identification: How To Use a Dichotomous Key

JoVE 10070

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University

A dichotomous key is a tool that identifies items in nature, such as leaves. This method is based on the idea of choosing between two characteristics. The word dichotomous comes from two Greek words that mean “to divide into two parts.” In a…

 Environmental Science

Quadruply Metal-Metal Bonded Paddlewheels

JoVE 10441

Source: Corey Burns, Tamara M. Powers, Department of Chemistry, Texas A&M University

Paddlewheel complexes are a class of compounds comprised of two metal ions (1st, 2nd, or 3rd row transition metals) held in proximity by four bridging ligands (most commonly formamidinates or carboxylates) (Figure 1). Varying the…

 Inorganic Chemistry

Community Diversity - Student Protocol

JoVE 10608

Measuring Biodiversity in Areas with Different Disturbance Regimes
NOTE: In this experiment, you will compare the biodiversity in a less disturbed area against a more highly disturbed area. HYPOTHESES: The experimental hypothesis could be that a less disturbed area will contain a greater diversity of species than a highly disturbed area. The null…

 Lab Bio

Tree Survey: Point-Centered Quarter Sampling Method

JoVE 10060

A number of methods are available for sampling forest communities. Point-centered quarter is one such method. It is used to gather information on the density, frequency, and coverage of tree species found in a forest. This information provides the ability to estimate the number of individual trees encountered, how often a certain tree occurs, how common the tree is…

 Environmental Science

Hardy-Weinberg & Genetic Drift - Student Protocol

JoVE 10560

Class Simulation
Begin by opening a new spreadsheet file. Following the Hardy-Weinberg equation where p is the frequency of a dominant allele A in a population, and q is defined as the frequency of a recessive allele B, input frequency p of allele A into cell B2, and frequency q of allele B into cell B3.
Assign the value 0.5 to cell C2.

 Lab Bio

Mental Rotation

JoVE 10115

Source: Laboratory of Jonathan Flombaum—Johns Hopkins University

Visual mental imagery refers to the ability to conjure images in one’s mind’s eye. This allows people to process visual material above and beyond the constraints of a current point-of-view; for example, a person could…

 Cognitive Psychology

Using a pH Meter

JoVE 5500

Source: Laboratory of Dr. Zhongqi He - United States Department of Agriculture

Acids and bases are substances capable of donating protons (H+) and hydroxide ions (OH-), respectively. They are two extremes that describe chemicals. Mixing acids and bases can cancel out or neutralize their extreme effects. A substance that is neither acidic…

 General Chemistry

Application of Group Theory to IR Spectroscopy

JoVE 10442

Source: Tamara M. Powers, Department of Chemistry, Texas A&M University

Metal carbonyl complexes are used as metal precursors for the synthesis of organometallic complexes as well as catalysts. Infrared (IR) spectroscopy is one of the most utilized and informative characterization methods of CO containing compounds. Group theory, or…

 Inorganic Chemistry

Bacterial Growth Curve Analysis and its Environmental Applications

JoVE 10100

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - Arizona University
Demonstrating Author: Luisa Ikner

Bacteria are among the most abundant life forms on Earth. They are found in every ecosystem and are vital for everyday life. For example, bacteria affect what people eat, drink, and breathe, and there are actually more…

 Environmental Microbiology

Heat Exchanger Analysis

JoVE 10391

Source: Alexander S Rattner and Christopher J Greer; Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA

Heat exchangers transfer thermal energy between two fluid streams, and are ubiquitous in energy systems. Common applications include car radiators (heat transfer from hot engine…

 Mechanical Engineering
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