North Pole

Source: Ali Bazzi, Department of Electrical Engineering, University of Connecticut, Storrs, CT. DC/DC converters are power electronic converters that convert DC voltages and currents from a certain level to another level. Typically, voltage conversion is the main purpose of DC/DC converters and three main types of conversion exist in a single converter: stepping up, stepping down, and stepping up or down. Among the most common step-up converters are boost converters (Refer to this collections...

The transfer function is a fundamental concept representing the ratio of two polynomials. The numerator and denominator encapsulate the system's dynamics. The zeros and poles of this transfer function are critical in determining the system's behavior and stability. Simple poles are unique roots of the denominator polynomial. Each simple pole corresponds to a distinct solution to the system's characteristic equation, typically resulting in exponential decay terms in the system's response.

This video demonstrates the technique used for preparation of organizer and animal pole explants from Xenopus laevis embryos, including the use of the eyebrow knife - a specialized dissection tool made of one's eyebrow. The protocol for assembling an adhesion assay is also given, which probes for the presence of key adhesion molecules present on the surface organizer or animal pole cells that are critical for proper development.

Source: Yong P. Chen, PhD, Department of Physics & Astronomy, College of Science, Purdue University, West Lafayette, IN Magnetic fields can be generated by moving charges, such as an electrical current. The magnetic field generated by a current can be calculated from the Maxwell equation. In addition, magnetic objects such as bar magnets can also generate magnetic fields due to microscopic dynamics of charges inside the material. Magnetic fields will exert magnetic force on other moving...

Source: Laboratory of Alan Lester - University of Colorado Boulder Most rock units exhibit some form of planar surfaces or linear features. Examples include bedding-, fault-, fracture-, and joint-surfaces, and various forms of foliation and mineral alignment. The spatial orientation of these features form the critical raw data used to constrain models addressing the origin and subsequent deformation of rock units. Although now over 100 years since its invention and introduction, the Brunton...