What's the difference between perturbation and variation?

Perturbation


Definition:

  • (n.) The act of perturbing, or the state of being perturbed; esp., agitation of mind.
  • (n.) A disturbance in the regular elliptic or other motion of a heavenly body, produced by some force additional to that which causes its regular motion; as, the perturbations of the planets are caused by their attraction on each other.

Example Sentences:

  • (1) These membrane perturbation effects not observed with bleomycin-iron in the presence of a hydroxyl radical scavenger, dimethyl thiourea, or a chelating agent, desferrioxamine, were correlated with the ability of the complex to generate highly reactive oxygen species.
  • (2) Ultraviolet difference spectrophotometry indicates that the inactivated enzyme retains its capacity for binding the nucleotide substrates whereas the spectral perturbation characteristic of 3-phosphoglycerate binding is abolished in the modified enzyme.
  • (3) It is suggested that laboratory experiments should be performed on perturbed systems only if simulations have shown that the methods of data analysis will be satisfactorily powerful and accurate.
  • (4) Thresholds were measured for detecting perturbations in a regular lattice of dots by modulating local dot density, local dot luminance, or some combination of the two.
  • (5) It is shown that when a constant current is applied such that a stable equilibrium and rhythmic firing are present, the following predictions are inherent in the HH system of equations: (a) Small instantaneous voltage perturbations to the axon given at points along its firing spike result in phase resetting curves (when new phase versus old phase is plotted) with an average slope of 1.
  • (6) Lower lip perturbation duration was manipulated to yield two different load conditions.
  • (7) The role of the Golgi complex in the post-translational oligosaccharide maturation of alpha-amylase was explored by use of the carboxylic ionophore, monensin (10(-7)M), a known perturbant of the structure and function of the Golgi complex.
  • (8) The importance of the ionic interaction due to the formation of the salt bridge between the Asp-27 and the pteridine ring in Escherichia coli dihydrofolate reductase-methotrexate complex has been studied by using the free-energy perturbation method.
  • (9) Presence of the monosynaptic reflex during platform perturbations at normal latencies suggests that balance problems in children with Down syndrome do not result from hypotonia, which researchers have defined as decreased segmental motoneuron pool excitability and pathology of stretch reflex mechanisms, but rather result from defects within higher level postural mechanisms.
  • (10) We have perturbed the dynamics of the nuclear lamins by means of cell fusion between mitotic and interphase cells and have studied redistribution of lamins in fused cells as a function of extracellular pH levels.
  • (11) In the coagulating gland, this compensatory response involved the proliferation of many cells which, in the absence of cytotoxic perturbation, would be non-proliferatie (Q cells).
  • (12) The effect of initial perturbation of the thrombus by a guide wire appears to be less important than the thrombus disruption and accelerated thrombolysis caused by the pulsatile delivery system.
  • (13) As before, subjects were instructed to either oppose the perturbation (Predictable Oppose) or relax the forearm muscles (Predictable Let-Go).
  • (14) Bivalent cations (Ca2+, UO2(2+) or Zn2+) in the subphase at pH 5.6 significantly modified the behaviour of mixed monolayers of fusogenic lipids with phospholipids; there was a parallel perturbing effect of fusogenic lipids on interactions between monolayers of phospholipids and bivalent cations.
  • (15) In particular, nitration of Tyr-51 provoked a structural perturbation in the globular region.
  • (16) Altering the biophysical characteristics of cell membranes by diet and membrane perturbing agents markedly influences thermosensitivity of cells.
  • (17) Paraphilias (PAs) and non-paraphilic sexual addictions (NPSAs) may be behaviors that share a common perturbation of central serotonin neuroregulation as a component of their pathophysiology.
  • (18) Two functions of these have been proposed: 1) that they are compatible osmolytes which regulate cell volume (against high external NaCl) without inhibiting proteins and 2) that methylamines (GPC and betaine) are counteracting osmolytes which stabilize proteins against perturbation from high renal urea.
  • (19) This high incidence of HER2 gene amplification with accompanying overexpression in non-invasive breast tumors suggests that perturbations of the HER2 oncogene are among the earliest and most common genetic lesions in human breast cancer.
  • (20) Hypophysectomy was selected as a model system for perturbing testicular cell types, since the cytological sequelae of this treatment post-hypophysectomy in the rat are well documented in the literature.

Variation


Definition:

  • (n.) The act of varying; a partial change in the form, position, state, or qualities of a thing; modification; alternation; mutation; diversity; deviation; as, a variation of color in different lights; a variation in size; variation of language.
  • (n.) Extent to which a thing varies; amount of departure from a position or state; amount or rate of change.
  • (n.) Change of termination of words, as in declension, conjugation, derivation, etc.
  • (n.) Repetition of a theme or melody with fanciful embellishments or modifications, in time, tune, or harmony, or sometimes change of key; the presentation of a musical thought in new and varied aspects, yet so that the essential features of the original shall still preserve their identity.
  • (n.) One of the different arrangements which can be made of any number of quantities taking a certain number of them together.

Example Sentences:

  • (1) The variation in thickness of the LLFL may modulate the species causing damage to the cells below it.
  • (2) There was appreciable variation in toothbrush wear among subjects, some reducing their brush to a poor state in 2 weeks whereas with others the brush was rated as "good" after 10 weeks.
  • (3) Correction for within-person variation in urinary excretion increased this partial correlation coefficient between intake and excretion to 0.59 (95% CI = 0.03 to 0.87).
  • (4) The coefficient of variation in the integrated area of a single peak is 16%.
  • (5) Sequence variation in the gp116 component of cytomegalovirus envelope glycoprotein B was examined in 11 clinical strains and compared with variation in gp55.
  • (6) Effects of habitual variations in napping on psychomotor performance, short-term memory and subjective states were investigated.
  • (7) A small variation in T1 was found between older (greater than 40 years) and younger (less than 40 years) subjects, but no such effect was observed in the case of T2.
  • (8) The variation of the activity of the peptidase with pH in the presence of various inhibitors was investigated in both control and insulted muscle fibres.
  • (9) This study examined both the effect of variations in optical fiber tip and in light wavelength on laser-induced hyperthermia in rat brain.
  • (10) = 19) with a very low, but statistically significant, correlation with the AUC, r = 0.35 (p less than 0.05), thus demonstrating a very great individual variation in sensitivity to cimetidine.
  • (11) Once the normal variations are mastered, appreciation of retinal, choroidal, optic nerve, and vitreal abnormalities is possible.
  • (12) Regression analysis on the 21 clinical or laboratory parameters studied showed that the only variable independently associated with CSF-FN was the total protein concentration in the CSF; this, however, explained only 14% of the observed variation in the CSF-FN concentration and did not show any correlation with CNS involvement.
  • (13) Pharmacokinetic parameters, such as these clearances, had large intersubject variations.
  • (14) Variability (CV = 0.7%) in body volume of a 45-year-old reference man measured by SH method was very similar to variation (CV = 0.6%) in mass volume of the 60-1 prototype.
  • (15) Further analysis of the role of sex steroid hormones is required in view of the sex variations reported.
  • (16) The overall result of this system has been to decrease the coefficients of variation to below 5% for all the milk and serum proteins tested.
  • (17) The variation in age-specific rates with age was similar for all cancers, as demonstrated by large positive correlation coefficients between age-incidence patterns averaged over all populations.
  • (18) Even though there are variations among equipment bearing the same model number it was considered worthwhile to make available relative cavitational and temperature data.
  • (19) Accordingly, LPA proved an extremely stable characteristic which did not show any substantial variations in the course of five years.
  • (20) Variation in patient mix was a major determinant of the large variations in resource use.