Effect of lag time

Biomedical sample analysis relies on appropriate sample collection. Although any result is unlikely to guide the response phase of the incident, the emergency response should include consideration of the collection of these samples. The best results are expected to be generated from samples taken as early as possible, and from patients considered to have had the greatest exposure. There is however little clear data available on the urgency of analysis in relation to the stability of markers, and on the effects of lag-times for bringing samples to the laboratory. 

Akande, O.F. Eord, J.E. Rowe, P.H. Rubinstein, M.H. The effects of lag-time and dwell-time on the compaction properties of 1 1 paracetamol/microcrystalline cellulose mixtures prepared by precompression and main compression. J. Pharm. Pharmacol. 1998, 50, 19-28. 

Example Regardless of the manufacturer of the hardware, the effect of a time lag on resolution is quite dramatic. The resolving power of linear instruments is improved by a factor of 3-4 and reflector instruments become better by a factor of about 2-3. [36] The advantages are obvious by comparison of the molecular ion signal of Ceo as obtained from a ReTOF instrument with continuous extraction (Fig. 4.7) and from the same instrument after upgrading with PIE (Fig. 4.12), or by examination of MALDI-TOF spectra of substance P, a low mass peptide, as obtained in continuous extraction mode and after PIE upgrade of the same instrument (Eig. 4.11). 

In reaching this conclusion we have assumed that no time lag affects the field that establishes the attraction between the particles. We have also considered particles under vacuum so no intervening medium enters the picture. Each of these simplifying approximations has the effect of overestimating the van der Waals attraction between particles at large separations from one another and embedded in a medium. We consider presently the effect of a time lapse between the interaction of a field with two different particles the effect of the medium is discussed in Section 10.8. 

The presence of significant amounts of dead time in a control loop can cause severe degradation of the control action due to the additional phase lag that it contributes (see Example 7.7). One method for compensating for the effects of dead time in the control loop has been suggested by SMITH<30>. This consists of the insertion of an additional element which is often termed the Smith predictor as it attempts to predict the delayed effect that the manipulated variable will have upon the process output. 

Spray-dried elderberry juice with high amounts of anthocyanin glucosides caused prolongation of the lag phase of copper induced oxidation of human LDL, while the maximum oxidation rate remained unchanged (Abuja et al., 1998). For peroxyl-radical-driven LDL oxidation, however, both prolongation of lag time and reduction of maximum oxidation rate occurred. When the extract was added after LDL oxidation was initiated, the elderberry extract demonstrated a pro-oxidative action. The pro-oxidative effect was more pronounced the longer the LDL oxidation was allowed to proceed before the extract was added. 

With pulsed or transient illumination, lag also results in a nonlinear detector response to incident light intensity. The effects of lag on the linearity of detector response can be reduced by using multiple readout scans, long dwell times, both resulting in longer readout times, or other schemes (13,14, ID ... 

Figure 3. Relative integrated signal showing the effect of lag as a function of dwell time controlled by channel time. Each channel consisted of500 pixels (delta Y = 500). Signal is due to a single pulse of a Xe strobe lamp (General Radio, 1539-A Stroboslave). Light was detected in zero order with a 20-p.m entrance slit. Dwell time o, 40 ns , 80 ns A, 160 ns ...

Figure 10.5 Effect of (a) time constant and (b) static gain, in the response of first-order lag systems.

Consideration of lag times also supports the conclusion of a transition from membrane to diffusion layer control. With membrane control the lag time is a function of hm and D. With a constant and little change in expected in this series, one might expect only small changes in tL if membrane control were in effect. This observation is made with C-l-C-4 esters. However, tL increased consistently from C-5-C-7 consistent with the influence of on A under diffusion layer control. Also, the change in membrane thickness should also result in a proportionate change in A that is observed with the C-6 and C-7 esters. It would appear that with the C-5 ester some membrane involvement persists since under diffusion layer control we would predict from observations with the 126-p,m membrane that tL should be 6.5 x 3.8 = 25 min for the 476-p,m membrane this value is less than the observed value. On the other hand, with membrane control, the tj predicted... 

Zeger SL, Thomas D, Dominici F et al (2000) Exposure measurement citot in time-series studies of air pollution concepts and consequences. Environ Health Perspect 108 419-426 Zeka A, Zanobetti A, Schwartz J (2005) Short term effects of particulate matter on cause specific mortality effects of lags and modification by city characteristics. Occup Environ Med 62 718-725... 

Similarly, Cu oxide DE growth post-CMP exhibits queue time effects as previous studies have indicated [19,20,22]. One study pointed out that a certain amount of lag time between plating and furnace anneal can help extend the post-CMP queue time DE free for up to 144 h [22]. The plating-anneal lag time dependence of DE implies that room temperature self-annealing of Cu during the lag time can alter the Cu microstructure to the extent that it enhances surface passivation and/or reduces Cu oxide... 

Fig. 3. Cumulative release provided by various release kinetics. A, Constant release, independent of time (zero order), such as that possible from a membrane reservoir device free of lag time or initial burst effects. B, Matrix or monolithic sphere with square root time release. C, First-order release A-zero order C-first order B-square root.

Reaction progress with time The effect of reaction time on the D.S. for acylations of AOT-coated starch nanoparticles with vinyl stearate, CL, and maleic anhydride are shown in Figure 2 and discussed below. Acylation with vinyl stearate starts after a 2 h lag period and by 24 h reached D.S. 0.7. Extending the reaction time to 48 h showed at most an increase in the D.S. to 0.8. The lag period observed for stearate acylation is likely due to the immiscibility of hydrophobic vinyl stearate and hydrophilic starch molecules. However, once a low degree of stearate ester formation occurred the solubility of vinyl stearate in the hydrophobically modified starch nanoparticles increases thus accelerating the reaction. In contrast, a lag period was not observed for the reaction with CL. This is consistent with a relatively higher miscibility of CL than vinyl stearate with the starch nanoparticles. 

In model-building and estimation, the within-coimtry diffusion is concerned with the diffusion pattern, the diffusion curve. The cross-border diffusion analysis pursues the question of the international order of adoption of innovations and the time-lag between the first adoption of an innovation by a (lead) country and the following adoption by other (lag) countries. Traditionally, diffusion theory and empirical studies have considered the diffusion process within a country and neglected to explain the national order of adoption of an innovation (Audretsch 1996, p. 110, Dekimpe et al. 1998b, p. 5). Even marketing studies which took the order of countries adopting an innovation into consideration were mainly focussed on the effects of the time lag on the form of the diffusion curve, for instance... 

Net-tension failures can be avoided or delayed by increased joint flexibility to spread the load transfer over several lines of bolts. Composite materials are generally more brittle than conventional metals, so loads are not easily redistributed around a stress concentration such as a bolt hole. Simultaneously, shear-lag effects caused by discontinuous fibers lead to difficult design problems around bolt holes. A possible solution is to put a relatively ductile composite material such as S-glass-epoxy in a strip of several times the bolt diameter in line with the bolt rows. This approach is called the softening-strip concept, and was addressed in Section 6.4. 

Although the experiments reported by Maurer et al. (1977) were performed for a completely different reason, namely, to study effects of vapor cloud explosions (see Section 6.4), fireballs were nevertheless generated. These experiments involved vessles of various sizes (0.226-1000 1) and containing propylene at 40 to 60 bar gauge pressure. The vessels were ruptured, and the released propylene was ignited after a preselected time lag. One of these tests, involving 452 kg of propylene, produced a fireball 45 m in diameter. 

The rate of heat conduction is further complicated by the effect of sunshine onto the outside. Solar radiation reaches the earth s surface at a maximum intensity of about 0.9 kW/ m. The amount of this absorbed by a plane surface will depend on the absorption coefficient and the angle at which the radiation strikes. The angle of the sun s rays to a surface (see Figure 26.1) is always changing, so this must be estimated on an hour-to-hour basis. Various methods of reaching an estimate of heat flow are used, and the sol-air temperature (see CIBSE Guide, A5) provides a simplification of the factors involved. This, also, is subject to time lag as the heat passes through the surface. 

Fig. 7.1.6 Influence of pH and temperature on the luminescence of Cbaetopterus photoprotein elicited by old dioxane and Fe2+ in 20 mM phosphate buffer. Left panel the effect of pH in phosphate buffer solutions of various pH values, at 22°C. Right panel the effect of temperature at pH 7.2. Luminescence was initiated by the injection of Fe2+. The time lag of the light emission after the Fe2+ injection was also shown in the right panel. From Shimomura and Johnson, 1966.

Another type of NR crosstalk, which has only recently been recognized, is the so-called nongenomic actions of several receptors that induce very rapid cellular effects. Effectively, evidence has accumulated over several decades that steroid receptors may have a role that does not require their transcriptional activation, such as modifying the activity of enzymes and ion channels. While the effects of steroids that are mediated by the modulation of gene expression do occur with a time lag of hours, steroids can induce an increase in several second messengers such as inositol triphosphate, cAMP, Ca2+, and the activation of MARK and PI3 kinase within seconds or minutes. Many mechanistic details of these nongenomic phenomena remain poorly understood. Notably, controversy still exists as to the identity of the receptors that initiate the non-genomic steroid actions. However, it now appears that at least some of the reported effects can be attributed to the same steroid receptors that are known as NRs. 

It is possible to distinguish between direct and indirect nOes from their kinetic behavior. The direct nOes grow immediately upon irradiation of the neighboring nucleus, with a first-order rate constant, and their kinetics depend initially only on the intemuclear distance r" indirect nOes are observable only after a certain time lag. We can thus suppress or enhance the indirect nOe s (e.g., at He) by short or long irradiations, respectively, of Ha- a long irradiation time of Ha allows the buildup of indirect negative nOe at He, while a short irradiation time of Ha allows only the direct positive nOe effects of Ha on He to be recorded. 

Owing to the lag time between initiation and effect, capsaicin is not used for treatment of acute pain from injury. Instead, topical capsaicin is used for chronic pain from musculoskeletal and neuropathic disorders. Capsaicin preparations have been studied in the treatment of pain from diabetic neuropathy, osteoarthritis, rheumatoid arthritis, postherpetic neuralgia, and other disorders.48 It is often used as an adjuvant to systemic analgesics in these chronic pain conditions. 

The inherent dynamics is governed by the poles, but the zeros can impart finer "fingerprint" features by modifying the coefficients of each term in the time domain solution. That was the point which we tried to make with the examples in Section 2.5 (p. 2-10). Two common illustrations on the effects of zeros are the lead-lag element and the sum of two functions in parallel. 

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