Glossary of the key notions in Bionics and beyond

Rabi → Isidor Isaac Rabi (1898–1988) was a Galician-born American physicist (Nobel laureate 1944), he discoverd the nuclear magnetic resonance.

Rabi frequency → The ~ is the frequency of population oscillation for a given atomic transition in a given light field. It is associated with the strength of the coupling between the light and the transition.

Rabi oscillations → A vacuum Rabi oscillation is a damped oscillation of an initially excited atom coupled to an electromagnetic resonator or cavity in which the atom alternately emits photon(s) into a single-mode electromagnetic cavity and reabsorbs them. The atom interacts with a single-mode field confined to a limited volume V in an optical cavity. Spontaneous emission results as a consequence of coupling between the atom and the vacuum fluctuations of the cavity field.

Racemic mixture → An exactly 50:50 mixture of crystals of both pure (-)- and pure (+)-enantiomers. It has a lower melting point than either pure enantiomer and shows no optical rotation.

Radiation resistance → ~ is that part of an antenna’s feedpoint resistance that is caused by the radiation of electromagnetic waves from the antenna. The ~ is determined by the geometry of the antenna, not by the materials of which it is made.

Radical (free radical) → ~ is a molecular entity possessing an unpaired electron. In a ~ reaction, the reaction may occur between a ~ and a non-radical, or between two radicals.

Radical polymerization → ~ is a chain-growth polymerization of monomers via a chain reaction initiated by a free radical. It involves three steps:

1. 
   initiation
   
2. 
   propagation
   
3. 
   termination
   

Radicofunctional name (functional class name) → Functional class name expresses the characteristic group as a class term written as a separate word following the name of a parent structure or a name derived from a parent structure. In the latter case, when the derived name is that for a substituent group (formerly called a ‘radical’), the method has been called ‘radicofunctional nomenclature’.

Radicofunctional nomenclature (functional class name) → Functional class name expresses the characteristic group as a class term written as a separate word following the name of a parent structure or a name derived from a parent structure. In the latter case, when the derived name is that for a substituent group (formerly called a ‘radical’), the method has been called ‘radicofunctional nomenclature’.

Radio frequency → Radio frequency (RF) is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals.

Radioactivity → ~ refers to the particles which are emitted from nuclei as a result of nuclear instability. The nucleus experiences the intense conflict between the two strongest forces in nature, so there are many nuclear isotopes which are unstable and emit some kind of radiation. The most common types of radiation are called alpha, beta, and gamma radiation, but there are several other varieties of radioactive decay. Radioactive decay rates are normally stated in terms of their half-lives.

Radiograph → Image made using x-ray radiation.

Radius of locality → the radius of the neighborhood, if r=1 then a 3x3 sub array is called as local neighborhood

Ramachandran plot → ~ depicts the energy of a conformation as a function of the torsion angles.

Random Access Memory (RAM) → An arbitrary access memory,which is a writeable and readable data storage device with random access.

Random-effects analysis → Intersubject analysis that treats the effect of the experimental manipulation as variable across subjects, so that it could have a different effect upon different subjects.

Range → The minimum and the maximum values of the measurements.

Rank of a matrix → ~ is a number indicating how many independent rows or columns are in a matrix

Raoult’s law → x₁=p₁/p₁⁰ where x₁ is the mole fraction of the solvent, p₁ is the vapour pressure above that solution and p₁⁰ is the vapour pressure above the pure solvent.

Raphe nuclei → Cell groups in the midline of the brainstem, which are composed of serotonin-producing neurons projecting fibers to most areas of the CNS.

Rapid eye movement (REM) sleep → A sleep phase, which is characterized by rapid movements of the eyes, deeply relaxed skeletal muscles, low voltage brain waves, increased pulse rate and irregular breathing.

Rate constant → Rate law is a differential equation that describes the dependence of the reaction rate (k) on the concentrations of species present in the reaction mixture. The rate equation is frequently used to substantiate or negate a proposed reaction mechanism. The k is the ~, which is a proportionality constant. The rate constant is independent of concentration, but it is temperature-dependent and characteristic for a specific reaction.

Rate law → A mathematical relation between the rate of a reaction and the concentration of reactants. ~ always has the form d[P]/dt=-k∏[R_i]ⁿⁱ where [P] is the concentration of a product and [R_i] is the concentration of the I’th reactants, k is the rate constant and ni is the order of reaction with respect to the i’th reactant.

Rate limiting step → In a serial reaction if one of the steps is far slower than the others, this reaction is called the ~ and the rate of the overall reaction can be approximated by the rate of the ~. The rate-limiting (or rate-determining) step has the highest transition-state energy in a multiple-step reaction.

Rational drug design → ~ is an in silico method of lead discovery that uses the knowledge of protein structure to predict its interaction with small ligands.

Ray optics model → In optics, a ray is an idealized narrow beam of light. Rays are used to model the propagation of light through an optical system, by dividing the real light field up into discrete rays that can be computationally propagated through the system by the techniques of ray tracing.

Rayleigh → John William Strutt, 3rd Baron Rayleigh (1842–1919) was an English physicist who (with William Ramsay) discovered the element argon (Nobel Prize, 1904). He also discovered the phenomenon now called ~ scattering, explaining why the sky is blue, and predicted the existence of the surface waves now known as Rayleigh waves.

Rayleigh quotient → ~ or Rayleigh–Ritz ratio for a complex hermitian matrix is a function, where the maximum value corresponds to the maximal eigen value of the matrix. See mathematical definition for details

Reactant → Materials which diminish through a reaction.

Reactant (reagent) → ~ is a substance that is consumed in the course of a chemical reaction. It is sometimes known, especially in the older literature, as a reagent, but this term is better used in a more specialized sense as a test substance that is added to a system in order to bring about a reaction or to see whether a reaction occurs (e.g. an analytical reagent).

Reaction coordinate → An arbitrary measure by which the progress of a reaction can be characterized.

Reaction cross section → A_rcs=(r_A+r_B)²·π is the cross section of collision cylinder.

Reaction free energy → The free energy different between the reactants and products.

Reaction kinetics → A discipline investigating the reactions in time.

Reaction mechanism → The mechanism of a reaction is a model explaining the overall reaction as a series of elementary reactions proceeding through a complex reaction.

Reaction order → The power exponent concerning to the concentration of the reactant in the rate law.

Reaction profile → It plots the free energy as a function of a particular reaction coordinate.

Reactive Ion Etching (RIE) → Ions in plasma reacts at the surface and sputter parts of it.

Reactivity → ~ is a kinetic term that involves a comparison of rate constants for similar reactions of different substances.

Read Only Memory (ROM) → A storage device, a memory which cannot be modified.

Readiness potential → see Bereitscahftspotential

Real solution → Solution which does not satisfy the laws valid only for ideal solutions.

Receiver coil → The ~ is located in the implanted internal unit of the cochlear implant. It receives the data transmitted by the transmitter coil and in some cases transmits back telemetry information.

Receiver noise → The amplifiers and mixers in the RX are noisy, and thus increase the total noise power. The noise figure is a measure of this effect.

Receptive field → The ~ of a sensory neuron is a region of space in which the presence of a stimulus will alter the firing of that neuron.

Reciprocal synapse → A synaptic connection between two neurons, where not just neuron A is presynaptic to neuron B, but B is also presynaptic to A.

Recombinant DNA → An artificial DNA molecule that is created by joining to unrelated (e.g. bacterial vector and human insert) DNA molecules.

Recording electrodes → ~ detect bioelectric signals in the peripheral or central nervous system

Recruitment → Progressive activation of motor units resulting increased muscle activity.

Recrystallized layer forming → Growing substrate layers above complete, metalized wafers.

Recurrent network → A neural network in which there is feedback.

Recurrent neural network → A class of neural networks, where the connections between the units form a directed cycle.

Redox reaction → A reaction during which the oxidation state of an atom is changed

Reduced Instruction Set Computer (RISC) → An arcihtecture with few instructions mainly solving specific problems

Reducing equivalents → A general term for an electron or an electron equivalentin the form of hydrogen atom or hydride ion

Reduction → The complete transfer of one or more electrons to a molecular entity (also called ‘electronation’). It also means a decrease in the oxidation number of any atom within any substrate. ~ is the reverse of the oxidation processes.

Reductionist approach → A scientific approach of exploration based on disassembly of a system into its constituents, exploration of the properties of the separate parts and then integrating the knowledge to interpret the function of the whole system

Redundancy → The number of participating muscles and joints are higher than necessary to execute an intended movement and there are many combinations of muscle activities and joint rotations to execute the given motor task.

Referential electrode → Electrode that is placed to a relatively distant place from the EEG generators, this way it serves as an „indifferent” quasi-zero potential electrode.

Reflected wave → The ~ corresponding to a given incident ray, is the wave reflected by the surface. The angle between the surface normal and the reflected ray is known as the angle of reflection.

Reflection → ~ is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated.

Reflection coefficient → When wave propagation in a medium containing discontinuities is considered (a wave experiences partial transmittance and partial reflectance when the medium through which it travels suddenly changes), the ~ describes either the amplitude or the intensity of a reflected wave relative to an incident wave.

Reflex action → ~ is an involuntary and nearly instantaneous movement in response to a stimulus coming from the peripherals.

Reflex arc → ~ is a neural pathway that mediates a certain reflex action

Refraction → ~ is the change in direction of a wave due to a change in its speed.

Refractory period → A time interval after an action potential when it is hard (or impossible) to elicit a new action potential.

Region Of Convergence (ROC) → A region where a z transform is defined because the series for those z complex values are finite.

Region-Of-Interest (ROI) → Any subset of voxels within the brain that the experimenter wants to investigate further. They might comprise an anatomical structure, or a cluster of activated voxels during the task. They often represent some area of pre-existing theoretical interest.

Regioselective reactions → ~ is one in which one direction of bond making or breaking occurs preferentially over all other possible directions. Reactions are termed completely (100%) regioselective if the discrimination is complete, or partially (x%), if the product of reaction at one site predominates over the product of reaction at other sites. The discrimination may also semi-quantitatively be referred to as high or low regioselectivity.

Register → Registers are the storing units of the CPUs and microprocessors of the computers that are quickly writeable and readable, contain temporary content, and it is usually able to process only one word (short chain of characters, 1 or 2 words is usually 2-4 bytes).

Register Transfer Level (RTL) → Description of functions that can be automatically synthesized for standardized cells, blocks, registers and logic.

Regression analysis → A collection of statistical methods whose goal is to establish a relationship between a dependent and one or more independent variables

Regressor → In a linear regression model, an independent - or right-hand-side - variable. That is, one of the variables that is being used to explain another.

Regular cell → Regular, non virtual and boundary cell of the cell array

Relative addressing mode → The addressing part of the instruction contains an address related to the base address of the operand. This can be the starting address of the datapage, the starting address of the memory segment, the address of the starting of the program, or the tárolóbeli address of the instruction itself. This is the base address. The real address is given by the processor by adding together the base address and the relative address.

Relative error → Specifies the percentage of the difference between the measured value and the actual value relative to the actual value.

Relative refractory period (RRP) → Only strong stimulus can generate an action potential.

Relative velocity → The relative velocity of the A and B particles is v_rel=v_A-v_B, Where v_A and v_B is the velocity vector with respect to the particle A and B, respectively.

Relaxation → Relaxation stands for a release of tension, a return to equilibrium.

Relaxation time → After excitation, the spins will tend to return to their equilibrium distribution, in which there is no transverse magnetization and the longitudinal magnetization is at its maximum value and oriented in the direction of the static magnetic field. It is observed that in the absence of applied RF magnetic field, the transverse magnetization decays toward zero with a characteristic time constant T2, and the longitudinal magnetization returns toward the equilibrium value Mo with a characteristic time constant T1.

Release probability → The probability of transmitter release from a presynaptic bouton.

Reliability → It refers to the consistency of accurate results over consecutive measurements over time.

Prefix etymology in measurement → See rapid eye movement sleep

Repetitive TMS (rTMS) → A variant of TMS, it has been tested as a treatment tool for various neurological and psychiatric disorders including migraines, strokes, Parkinson’s disease, dystonia, tinnitus, depression and auditory hallucinations.

Replacement name → ~ is in which the replacement of an atom or a group of a parent structure by another atom or group is indicated by affixes attached to or inserted into the name of the parent structure.

Replication → The process through which an identical copy of an original nucleic acid (usually double-starnded DNA) is made.

Representation capabilities → How many different tasks can be represented by an FFNN

Residual variance → The variability in the data that remains unexplained after accounting for the model factors.

Residual Volume → After the maximum expiration, approx. 1300 ml air remains in the lungs.

Resistor divider → Regardless of the input value, the ~ defines a permanent relationship.

Resolution → The separation of a racemic modification into its pure enantiomers.

Resonance → ~ is a phenomenon occuring when the excitation has a same form as one of the components in the system response. E.g. if the system has a transient response with exponential (trigonometrical) type at p0 (root of the characteristic polynom) and we excite the system with the same exponential (trigonometrical) type input.

Resonance (chemistry) → In the context of chemistry, the term ‘RESONANCE’ refers to the representation of the electronic structure of a molecular entity in terms of contributing structures. ~ among contributing structures means that the wavefunction is represented by ‘mixing’ the wavefunctions of the contributing structures. The concept is the basis of the quantum mechanical valence bond methods. The resulting stabilization is linked to the quantum mechanical concept of ‘resonance energy’. The term ~ is also used to refer to the delocalization phenomenon itself.

Resonance energy → ~ is the difference in potential energy between the actual molecular entity and the contributing structure of lowest potential energy. The ~ cannot be measured, but only estimated, since contributing structures are not observable molecular entities.

Resonator neuron → A type of neuron which responds the most to input at specific (non-zero) frequencies.

Rest mass → One of the consequences of Einstein’s special theory of relativity (1905) is that the mass of an object increases with its velocity relative to the observer. When an object is at rest (relative to the observer), it has the usual (inertial = tendency to resist an applied force) mass that we are all familiar with. This is called the ‘rest mass’ of the object.

Rest mass of the electron → The term “rest mass” comes from the need to take account of the effects of special relativity on the apparent (or “observed”) mass of an electron. It is impossible to “weigh” a stationary electron (it is one of the fundamental constants of physics), and so all practical measurements must be carried out on moving electrons. However special relativity shows that the mass of an object appears to increase as its speed v (relative to the observer) approaches the speed of light c.

Resting activity → The activity of the muscle after the instetion of the electrode in relaxed muscles. ~ has two types: insertional activity and spontaneous activity.

Resting potential → The steady state membrane potential of a neuron in the absence of incoming synaptic or sensory influences

Restriction endonucleases → Enzymes of bacterial origin that recognize and cleave the DNA molecule at special (4-6-bp-long) sequences.

Retarded potential → The ~ formulae describe the scalar or vector potential for electromagnetic fields of a time-varying current or charge distribution. The retard between cause and effect occurs because the signal takes a finite time, corresponding to the velocity of light, to propagate from the source of the field to the point where an effect is produced or measured.

Retarding voltage → If the anode is negative with respect to the cathode, the weaker electrons emitted by heating the cathode fail to reach the anode, it repels the approaching electrons. The potential difference across the electrodes is called the retarding voltage

Retention of configuration → ~ is the preservation of integrity of the spatial arrangement of bonds to an chiral centre during a chemical reaction or transformation. It is also the configurational correlation when a chemical species Xabcd is converted into the chemical species Xabce having the same relative configuration.

Retina → The eyeball is formed by three membranous layers; an outer fibrous, a middle vascular and an inner neuronal one. The ~ is the light-sensitive inner layer of the eyeball.

Retinal → Cofactor of bacteriorhodopsin.

Retinal cones → Photoreceptor cells in the retina, which function the best in bright light. They have low light sensitivity, fast response, and are responsible for color vision and high resolution.

Retinal rods → Photoreceptor cells in the retina, which function the best at low light intensities. They are very light sensitive (can even detect a single photon), have low resolution, slow response to light, and only signal the intensity of the light (do not detect colors).

Retinitis pigmentosa → A type of progressive retinal dystrophy, a group of inherited disorders in which abnormalities of the photoreceptors or the retinal pigment epithelium of the retina lead to progressive visual loss.

Retinotopic /Visuotopic organization → Retinotopy describes the spatial organization of the neuronal responses to visual stimuli. There is an orderly arrangement, which emerges from the spatial specificity of connections between neurons in different parts of the visual system; cells in each structure can be seen as forming a map of the visual field (also called a retinotopic map, or a visuotopic map).

Retrograde → From the axon terminal to the cell body.

Retrograde propagating action potential → Action potential propagation from the soma towards the distal dendrites.

Reuptake → The process of reabsorbtion of substances (e.g. neurotransmitters), which was secreted by the neuron itself before.

Reversal potential → The membrane potential at which there is no net (overall) flow of ions of a particular type from one side of the membrane to the other. At this potential value the electrical and chemical driving forces are in equilibrium for the given ion.

Reverse cholesterol transport → the route of cholesterol from peripheral tissues to the liver using HDL as a main carrier

Reverse range → The voltage range where there is no current in the semiconductor.

RF coil → Coil used for transmitting RF pulses and/or receiving MR signals. Commonly used in birdcage coil, saddle coil, or solenoid coil configurations for MR imaging.

RF pulse → Burst of RF magnetic field delivered to object by RF transmitter. For RF frequency near the Larmor frequency, it will result in rotation of the macroscopic magnetization vector in the rotating frame of reference (or a more complicated nutational motion in the stationary frame of reference). The amount of rotation will depend on the strength and duration of the ~; commonly used examples are 90° (π/2) and 180° (π) pulses.