Chemotaxis is the movement of an organism or entity in response to a chemical stimulus. Somatic cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. This is important for bacteria to find food by swimming toward the highest concentration of food molecules, or to flee from poisons. In multicellular organisms, chemotaxis is critical to early development and development as well as in normal function and health. In addition, it has been recognized that mechanisms that allow chemotaxis in animals can be subverted during cancer metastasis. The aberrant chemotaxis of leukocytes and lymphocytes also contribute to inflammatory diseases such as atherosclerosis, asthma, and arthritis. Sub-cellular components, such as the polarity patch generated by mating yeast, may also display chemotactic behavior.
A pointing device is a human interface device that allows a user to input spatial data to a computer. CAD systems and graphical user interfaces (GUI) allow the user to control and provide data to the computer using physical gestures by moving a hand-held mouse or similar device across the surface of the physical desktop and activating switches on the mouse. Movements of the pointing device are echoed on the screen by movements of the pointer and other visual changes. Common gestures are point and click and drag and drop.
In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force. It describes the rate of change of angular momentum that would be imparted to an isolated body.
Fitts's law is a predictive model of human movement primarily used in human–computer interaction and ergonomics. The law predicts that the time required to rapidly move to a target area is a function of the ratio between the distance to the target and the width of the target. Fitts's law is used to model the act of pointing, either by physically touching an object with a hand or finger, or virtually, by pointing to an object on a computer monitor using a pointing device. It was initially developed by Paul Fitts.
The angular displacement, also called angle of rotation or rotational displacement, of a physical body is the angle through which the body rotates around a centre or axis of rotation. Angular displacement may be signed, indicating the sense of rotation ; it may also be greater than a full turn.
In navigation, dead reckoning is the process of calculating the current position of a moving object by using a previously determined position, or fix, and incorporating estimates of speed, heading, and elapsed time. The corresponding term in biology, to describe the processes by which animals update their estimates of position or heading, is path integration.
The relative strength index (RSI) is a technical indicator used in the analysis of financial markets. It is intended to chart the current and historical strength or weakness of a stock or market based on the closing prices of a recent trading period. The indicator should not be confused with relative strength.
Haptotaxis is the directional motility or outgrowth of cells, e.g. in the case of axonal outgrowth, usually up a gradient of cellular adhesion sites or substrate-bound chemoattractants. These gradients are naturally present in the extracellular matrix (ECM) of the body during processes such as angiogenesis or artificially present in biomaterials where gradients are established by altering the concentration of adhesion sites on a polymer substrate.
Ralph Snyderman is Chancellor Emeritus at Duke University, James B. Duke Professor of Medicine, and Executive Director of the Duke Center for Personalized Health Care. He served as chancellor for health affairs and dean of the School of Medicine from 1989 to July 2004. Under his leadership, Duke University created the Duke University Health System (DUHS) to develop and operate a comprehensive health delivery system, and he was its founding President and Chief Executive Officer. DUHS, with its practice networks, ambulatory care centers, home health services, community hospitals, university hospital, and satellite collaborations demonstrated the power of academic medicine to deliver the best of care to broad communities. Snyderman helped lead the creation of the largest academic clinical research organization worldwide. During his tenure, Duke University Hospital was ranked 6th overall in the nation and its medical school ranked 4th. Snyderman is a leader in the conception and development of personalized health care, an evolving model of national health care delivery. He has articulated the need to move the current focus of health care from the treatment of disease-events to personalized, predictive, preventive, and participatory care that is focused on the patient. As Senior Vice-President at Genentech, he led the development of powerful new molecular biology therapeutics. Ralph Snyderman was the recipient of the 2012 David E. Rogers Award from the Association of American Medical Colleges which recognized him as "The Father of Personalized Medicine." He is a member of the Association of American Medical Colleges, Association of American Physicians, American Academy of Arts & Sciences, and the National Academy of Medicine.
Leukocyte extravasation is the movement of leukocytes out of the circulatory system and towards the site of tissue damage or infection. This process forms part of the innate immune response, involving the recruitment of non-specific leukocytes. Monocytes also use this process in the absence of infection or tissue damage during their development into macrophages.
Linear motion, also called rectilinear motion, is one-dimensional motion along a straight line, and can therefore be described mathematically using only one spatial dimension. The linear motion can be of two types: uniform linear motion, with constant velocity ; and non-uniform linear motion, with variable velocity. The motion of a particle along a line can be described by its position , which varies with (time). An example of linear motion is an athlete running a 100-meter dash along a straight track.
Bacterial motility is the ability of bacteria to move independently using metabolic energy. Most motility mechanisms which evolved among bacteria also evolved in parallel among the archaea. Most rod-shaped bacteria can move using their own power, which allows colonization of new environments and discovery of new resources for survival. Bacterial movement depends not only on the characteristics of the medium, but also on the use of different appendages to propel. Swarming and swimming movements are both powered by rotating flagella. Whereas swarming is a multicellular 2D movement over a surface and requires the presence of surfactants, swimming is movement of individual cells in liquid environments.
The instant center of rotation of a body undergoing planar movement is a point that has zero velocity at a particular instant of time. At this instant, the velocity vectors of the other points in the body generate a circular field around this center of rotation which is identical to what is generated by a pure rotation.
Sperm guidance is the process by which sperm cells (spermatozoa) are directed to the oocyte (egg) for the aim of fertilization. In the case of marine invertebrates the guidance is done by chemotaxis. In the case of mammals, it appears to be done by chemotaxis, thermotaxis and rheotaxis.
Sperm chemotaxis is a form of sperm guidance, in which sperm cells (spermatozoa) follow a concentration gradient of a chemoattractant secreted from the oocyte and thereby reach the oocyte.
Targeted drug delivery is one of many ways researchers seek to improve drug delivery systems' overall efficacy, safety, and delivery. Within this medical field is a special reversal form of drug delivery called chemotactic drug targeting. By using chemical agents to help guide a drug carrier to a specific location within the body, this innovative approach seeks to improve precision and control during the drug delivery process, decrease the risk of toxicity, and potentially lower the required medical dosage needed. The general components of the conjugates are designed as follows: (i) carrier – regularly possessing promoter effect also on internalization into the cell; (ii) chemotactically active ligands acting on the target cells; (iii) drug to be delivered in a selective way and (iv) spacer sequence which joins drug molecule to the carrier and due to it enzyme labile moiety makes possible the intracellular compartment specific release of the drug. Careful selection of chemotactic component of the ligand not only the chemoattractant character could be expended, however, chemorepellent ligands are also valuable as they are useful to keep away cell populations degrading the conjugate containing the drug. In a larger sense, chemotactic drug-targeting has the potential to improve cancer, inflammation, and arthritis treatment by taking advantage of the difference in environment between the target site and its surroundings. Therefore, this Wikipedia article aims to provide a brief overview of chemotactic drug targeting, the principles behind the approach, possible limitations and advantages, and its application to cancer and inflammation.
Chemorepulsion is the directional movement of a cell away from a substance. Of the two directional varieties of chemotaxis, chemoattraction has been studied to a much greater extent. Only recently have the key components of the chemorepulsive pathway been elucidated. The exact mechanism is still being investigated, and its constituents are currently being explored as likely candidates for immunotherapies.
An incremental encoder is a linear or rotary electromechanical device that has two output signals, A and B, which issue pulses when the device is moved. Together, the A and B signals indicate both the occurrence of and direction of movement. Many incremental encoders have an additional output signal, typically designated index or Z, which indicates the encoder is located at a particular reference position. Also, some encoders provide a status output that indicates internal fault conditions such as a bearing failure or sensor malfunction.
Histogram of Oriented Displacements (HOD) is a 2D trajectory descriptor. The trajectory is described using a histogram of the directions between each two consecutive points. Given a trajectory T = {P1, P2, P3, ..., Pn}, where Pt is the 2D position at time t. For each pair of positions Pt and Pt+1, calculate the direction angle θ(t, t+1). Value of θ is between 0 and 360. A histogram of the quantized values of θ is created. If the histogram is of 8 bins, the first bin represents all θs between 0 and 45.
Formyl peptide receptor 1 is a cell surface receptor protein that in humans is encoded by the formyl peptide receptor 1 (FPR1) gene. This gene encodes a G protein-coupled receptor cell surface protein that binds and is activated by N-Formylmethionine-containing oligopeptides, particularly N-Formylmethionine-leucyl-phenylalanine (FMLP). FPR1 is prominently expressed by mammalian phagocytic and blood leukocyte cells where it functions to mediate these cells' responses to the N-formylmethionine-containing oligopeptides which are released by invading microorganisms and injured tissues. FPR1 directs these cells to sites of invading pathogens or disrupted tissues and then stimulates these cells to kill the pathogens or to remove tissue debris; as such, it is an important component of the innate immune system that operates in host defense and damage control.
