Scientists identified the plasma membrane in the 1890s and its principal chemical components (lipids and proteins) by 1915. The model for plasma membrane structure, proposed in 1935 by Hugh Davson and James Danielli, was the first model to be widely accepted in the scientific community. The model was based on the plasma membrane's "railroad track" appearance in early electron micrographs. Davson and Danielli theorized that the plasma membrane's structure resembled a sandwich with the analogy of...

Cells migrating in response to external stimuli form lamellipodia, which are thin membrane protrusions supported by a mesh of linked, branched, or unbranched actin filaments. These actin filaments interact with myosin motor proteins, creating the dynamic actomyosin complex within the cytoskeleton. Contractility, or the ability to generate contractile stress, is inherent to the actomyosin complex. It helps cells detect the stiffness of the surrounding ECM and exert contractile force for...

The German physicist Heinrich Hertz (1857–1894) was the first to generate and detect certain types of electromagnetic waves in the laboratory. Starting in 1887, he performed a series of experiments that confirmed the existence of electromagnetic waves and verified that they travel at the speed of light. Hertz used an alternating-current RLC (resistor-inductor-capacitor) circuit that resonated at a known frequency and connected it to a loop of wire. High voltages induced across the gap in the...

The Laplace transform is an indispensable mathematical technique for simplifying the resolution of differential equations by converting them into more manageable algebraic expressions. The Laplace transform of a function is denoted by L[x(t)], where x(t) is the time-domain function. The laplace transform is mathematically expressed as

Sigmund Freud, an Austrian neurologist born in 1856, significantly influenced psychology through his exploration of the unconscious mind. His interest in patients suffering from hysteria and neurosis — conditions without apparent physical causes — led him to theorize the existence of an unconscious mind, a repository for feelings and urges beyond our awareness. Freud's innovative approach included techniques such as dream analysis, free association, and attention to slips of the tongue to...

Gestalt psychology, founded by Max Wertheimer, Kurt Koffka, and Wolfgang Kohler, emphasizes the importance of understanding perception as an organized whole. Developed as a counter to Wilhelm Wundt's structuralism, this approach posits that our perceptions are more than just the sum of sensory parts; they are comprehensive wholes where the relationships between parts define the perception. The principle "The whole is greater than the sum of its parts" encapsulates this view, illustrating how...