Elapsed Times Research Articles

Structural connotations of bioactivity in a series of organophosphinates

AbstractPretreatment before exposure is one of the options for temporarily protecting persons liable to exposure to toxic organophosphorus compounds in agricultural or warfare situations. It is known that organophosphinates interact with neuronal cholinesterases, but that the latter may spontaneously reactivate in time. Before that reactivation, the enzyme is protected against comlexation with organophosphates. In this study, geometrically optimized unitary molecular indices, i.e., the molecular transforms, FTm, FTe, and FTc, indicating general, electronic, and charge properties, respectively, and the analogous normalized molecular moments, Mn, Me, and Mc, were calculated for a number of phosphinates. These indices were subsequently used in correlation trials with spontaneous reactivation percentages at specific elapsed times, as well as in clustering procedures, to evaluate the effect of structure variations on the reactivation percentages. The results of these studies are discussed, as is the effect of the octanol/water partition coefficient on the noted bioactivity. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005

Impact of Elapsed Treatment Time on Outcome of External-Beam Radiation Therapy for Localized Carcinoma of the Prostate

The purpose of this study was to evaluate the impact of elapsed treatment time in external-beam radiation therapy for localized prostate carcinoma. The medical records of 1083 patients with localized prostate carcinoma treated between 1970 and December 1999 with external irradiation alone were reviewed. Median follow-up was 6 years (range, 4-24 years). Since 1987, prostate-specific antigen levels were obtained in 687 patients before the initiation of radiation therapy, and all patients seen in follow-up had prostate-specific antigen determinations. There were 344 patients with T1c, 496 with T2, and 243 with T3 tumors. The elapsed treatment time was divided into < or = 7, 7.1-9, or > 9 weeks. Local tumor control was determined by rectal examination and cause-specific survival or prostate-specific antigen failure according to American Society of Therapeutic Radiology and Oncology consensus criteria. Because of dose-escalation studies, tumor dose levels ranged from 66-73.8 Gy, given in 1.8- to 2-Gy fractions. In patients with stage T1c, local failure ranged from 0% to 10% with doses < or = 72 Gy with; elapsed treatment time had no impact. No pelvic failures were detected in 88 patients receiving doses > 72 Gy. In patients with T2 who received < or = 70 Gy, overall pelvic failure rate was 4% (12/306) in those with an elapsed treatment time of < or = 9 weeks, in contrast to 27% (12/44) for those with an elapsed treatment time > 9 weeks; at 10 years, patients with T2 tumors treated in > 9 weeks had a higher actuarial pelvic failure rate (35%), in contrast to 5% to 18% with shorter treatment times. For patients with T2 tumors who received 70-72 Gy, pelvic failure rate ranged from 0% to 32%, and there were no failures in 37 patients treated to higher doses. In patients with prostate-specific antigen values whose tumors were stage T1c, the chemical failure rate was 41% (60/147) with a tumor dose < 70 Gy, compared with 17% (4/24) in those who received higher doses. In patients with stage 2 disease who were treated with < 70 Gy, the chemical failure rate was 31%, and the rate was 12%-18% in those who received higher doses. In stage T3, the clinical pelvic failure rate ranged from 25% to 32% in the three elapsed time groups, and the chemical failure rate ranged from 48% to 69%, and there was no significant correlation with elapsed time or total irradiation dose. Cause-specific survival without chemical failure in patients with stage T1c disease at 10 years was 85%-90% in the three elapsed treatment time groups. In patients with stage T2 disease, the corresponding values were 80% and 90% for elapsed treatment times < 9 weeks, in contrast to 65% for patients treated > 9 weeks. In patients with stage T3 disease, cause-specific survival was about 60% in all elapsed treatment groups. There was no significant correlation of elapsed treatment time with urinary or rectal morbidity. Patients treated with radiation therapy for stage T2 localized prostate carcinoma showed a greater incidence of pelvic and chemical failures and a lower cause-specific survival when elapsed treatment time was > 9 weeks in comparison with the failure and survival rates occurring with shorter times. Higher doses of irradiation (> 72 Gy) eliminate the influence of prolongation of treatment time on outcome.

Creep Prediction of a Printed Wiring Board For Separable Land Grid Array Connector

The paper presents a study of creep behavior of a printed wiring board caused by the mechanical fastening of separable connector, known as a land grid array. Time-temperature superposition method was employed to predict the lifetime creep behavior. A low-cost testing method based on the ASTM D790 three-point bending procedure was developed to predict and characterize creep of polymeric materials under low temperature, low stress, and large elapsed times.

Patients with chest pain calling 9-1-1 or self-transporting to reach definitive care: which mode is quicker?

ObjectiveWe examined differences in transport times for patients with chest pain who used private transportation compared with patients who used emergency medical services (EMS) to reach definitive medical care. MethodsThis was a retrospective cohort study with data used from the Rapid Early Action for Coronary Treatment (REACT) trial conducted in 20 US cities. Elapsed time to care was examined through the use of (1) decision to seek care to initial care (emergency department [ED] arrival versus EMS arrival on scene [n=1209]); (2) decision to ED arrival (for both groups [n=2388]); (3) time to thrombolytic therapy once admitted to the ED (for both groups [n=309]); and (4) decision to seek care to thrombolytic therapy (n=276). Elapsed travel times were ranked within Zip Codes and submitted to a nested analysis of variance model to determine if elapsed times were different between modes of transport. ResultsPrivate transportation (35 minutes) resulted in faster ED arrival than using EMS (39 minutes, P = .0014). However, if one considers EMS treatment to be initial care, calling 9-1-1 (6 minutes) resulted in much quicker care than patients using private transportation to the ED (32 minutes, P < .001). Transport by EMS resulted in a shorter elapsed time to thrombolytic administration compared with patients using private transportation when considering ED “door-to-needle” time (32 vs 49 minutes, respectively [P < .001]) or time from decision to seek care until administration of thrombolytic therapy (75 vs 92 minutes, respectively, [P = .042]). ConclusionsAlthough private transportation results in a faster trip to the ED, quicker care is obtained with the use of EMS.

Dimensional Accuracy of Dental Casts: Influence of Tray Material Selection and Multiple Pours at Varying Elapsed Times after Impression Making

Dimensional Accuracy of Dental Casts: Influence of Tray Material Selection and Multiple Pours at Varying Elapsed Times after Impression Making

Access to care: What should we be measuring?

Some of the key measures on which emergency departments are judged concern access to care. In Australasia, the most common current measure of access is the percentage of patients who are seen within a specified time for each category of the national triage scale. Access measures regarding availability of in-patient beds is less uniform, but tends to be related to the number of patients who spend longer than a specified time in the emergency department. There are, however, measurables that are demonstrative of departmental process rather than being simple waiting time quantiles. These include mean and median elapsed times, together with standard deviations and coefficient of variation for each of the indicators. These measures better describe the central tendency and spread of performance, both of which are fundamentally important to any measure of the quality of process. This paper discusses the use of these broader and more descriptive indicators of process.

Investigation of the Long-Term Performance of Zero-Valent Iron for Reductive Dechlorination of Trichloroethylene

This research investigated the long-term performance of zero-valent iron for mediating the reductive dechlorination of trichloroethylene (TCE). Over a 2-year period, rates of TCE dechlorination in columns packed with iron filings were measured in simulated groundwaters containing either 3 mM CaSO4, 5 mM CaCl2, or 5 mM Ca(NO3)2. At early elapsed times, TCE reaction rates were pseudo-first-order in TCE concentration and were independent of the solution pH. With increasing elapsed time, reaction rates deviated from pseudo-first-order behavior due to reactive site saturation and increased iron surface passivation toward the influent end of each column. The extent of passivation was dependent on both the TCE concentration and the background electrolyte solution. For most of the investigation, TCE reaction rates in 3 mM CaSO4 and 5 mM CaCl2 solutions were statistically identical at the 0.05 confidence level. However, TCE reaction rates in 5 mM Ca(NO3)2 were slower. In columns operated using chloride- and sulfate-containing waters, the effective half-life for TCE dechlorination increased from approximately 400 min after 10 days elapsed to approximately 2500 min after 667 days. The effective TCE half-life in the nitrate-containing water increased from approximately 1500 min after 10 days to approximately 3500 min after 667 days. Measurements of iron corrosion rates in nitrate and chloride solutions showed that nitrate contributed to increased iron surface passivation and decreased rates of iron corrosion. Corrosion current measurements indicated that halocarbon reduction on fresh iron surfaces was cathodically controlled, whereas on aged iron surfaces, iron corrosion was anodically controlled. Anodic control of iron corrosion contributed to the development of reactive site saturation with time and to similar reaction rates for TCE and perchloroethylene. Passivation of the iron surfaces was found to be dependent on the adhering tendency of the corrosion products and not on the overall mass of corrosion products in the columns. The decrease in TCE reaction rates over time can be attributed to anodic control of iron corrosion and not to increasing reactant mass transfer limitations associated with diffusion through porous corrosion products.

Smoke Exposure of Women and Young Children in Highland Guatemala: Prediction and Recall Accuracy

In order to measure accurately indigenous Guatemalan women and young children's exposure to smoke from cooking fires, three techniques were compared: 1) observation; 2) recall 24 hours later based on duration of activities; and 3) recall 24 hours later based on the time each activity started and stopped (elapsed time). To measure recall accuracy, 43 women and their children under two years were observed during meal preparation and consumption, and the next day were asked to recall these activities. Women were reasonably accurate when recalling durations, but recall was significantly less accurate using elapsed times. Recall accuracy increased when two days' measurements were averaged. Women spent more time in the kitchen if they had a husband, and spoke only the indigenous language. For children, mothers' patterns and child's age were associated with time in the kitchen. Children who could walk spent significantly less time in the kitchen than non-walkers. Implications for action to prevent indoor air pollution for women and children are discussed.

The kinetics of insecticide action. Part IV: the in‐vivo distribution of pyrethroid insecticides during insect poisoning

AbstractThe distribution of pyrethroids in insects has been studied using a combination of mathematical modelling and experimental observation. This approach has resulted in the formulation of a physiological model of the pharmaco‐kinetics of cypermethrin applied topically to larvae of Spodoptera littoralis. Development of this model from simpler two‐ and three‐compartment models is described. Simple models, whilst capable of complex behaviour, consider only the average rates and magnitudes of pharmaco‐kinetic processes over whole animals, and cannot account for differences in concentration of insecticide between individual tissues. This can be achieved by using physiological models, but these require more experimental information for their validation. Moreover, unless simplifying assumptions are made, analytical solutions are not feasible for the large number of equations necessary to define such models.The modelling studies prompted an investigation of (1) in‐vivo binding of insecticide to insect tissues, (2) the sizes of body compartments, and (3) the factors which affect the distribution of toxicant between these compartments. Binding has a marked effect on pharmacokinetic profiles and may result in oscillatory behaviour. During poisoning, the total bound cypermethrin increases proportionally to the cube root of the elapsed time. This results in a rapid rate of increase over early elapsed times (&lt; 3h) which slows to approach a more linear form thereafter. Average sizes for the body compartments of larvae of Spodoptera littoralis Boisd, and the steady‐state distribution of cypermethrin in these compartments are described. Although the haemolymph, which acts as the main distributive phase during poisoning, forms the largest compartment by volume, it has a low affinity for cypermethrin and distribution reaches steady state within 5 min after topical application. The nerve cord (the target tissue), which is the smallest compartment, has the highest steady‐state concentration of cypermethrin. The distribution of cypermethrin in larval tissues is related to the ratios of tissue dry matter to water content.

Field‐scale transport of interacting solutes through the unsaturated zone: 2. Analysis of the spatial variability of the field response

The effect of physicochemical interactions between the soil solution and the soil matrix on the spatial variability of the soil‐dependent variables during transient transport of mixed Na/Ca−Cl salts through the unsaturated zone of a large field‐scale soil is analyzed. The spatial variability of the soil water and solute transport properties evaluated in part I were used as inputs to a conceptual stochastic model describing one‐dimensional vertical transport of water and soil‐interacting solutes through the unsaturated zone of a spatially variable soil, viewed as a collection of vertically homogeneous and independent soil columns. Using data of the spatial distributions of pertinent soil properties from the Bet Dagan field, the transport process was simulated for boundary and initial conditions pertinent to the application of low‐salinity and low‐alkalinity waters (rain) to the surface of a saline‐alkaline soil, considering effects of the soil solution concentration and composition on the soil water and solute transport properties. The spatial variability (in terms of field averages and coefficients of variation CV) of the profiles of the soil water content θ, the chloride concentration C, and the sodium adsorption ratio SAR of the soil solution and the soil hydraulic conductivity K at given elapsed times t were presented and compared with those evaluated from simulations of the same boundary value problem where the effect of the soil solution concentration and composition on the water and solute transport properties was disregarded. Results of the analyses suggested that because of soil solution‐soil matrix interactions the field‐average movement of both the water and the solutes may be retarded and their spatial variability may be increased relative to the case where these interactions had not been considered. In the Bet Dagan field, after t = 5 hours of continuous infiltration, the field averages of the positions of the wetting front and the chloride front were retarded by 10 and 15%, respectively; the relative variabilities of the positions of these fronts were increased by 16 and 38%, respectively; and the equivalent effective dispersivity was increased by 18%, relative to the reference inert case.

Human patellar reflex and conditioned reflex compared electromyographically

Inspite of continued work on the stretch reflex and “voluntary” movement study of the conditioned stretch reflex declined early in this century. The present experiments surveyed seven classical conditioning regimens for the human rectus femoris EMG seen after a blow to the patellar tendon. It was possible to (1) rule out conditioning to a knee touch that occured together with the tap, (2) establish weak conditioned stimulus, Sc, control for a tape recorder click and subsequent fist clench that preceded the tap by variable elapsed times, and (3) establish strong Sc control for a tone that sounded an invariant 0.27 sec before the tap. There were large differences, however, in Sc power across subjects, as measured by amplitude, latency, and frequency of conditioned EMG activity that occured prior to tap or when the tap was omitted. Purely reflexive responses, especially later EMG segments, also varied in amplitude and frequency, to support a conclusion that numerous controlling stimuli added or competed from trial to trial. Further disclosure of Sc contributions, including those from movement-generated stimulation, is warranted, especially for behaviors whose rhythmic timings, as in locomotion, might favor Pavlovian conditioning.

Estimating the probability of occurrences of surface faulting earthquakes on the Wasatch fault zone, Utah

abstract Although geological and geomorphic evidence strongly suggests that the Wasatch fault zone has generated large-magnitude earthquakes in late Quaternary time, the fault zone has not been associated with earthquakes greater than magnitude 512 in the past 133 yr. Therefore, realistic estimates of the likelihood of future damaging earthquakes must be based on more than historical seismicity data. The data base can be expanded by collecting site-specific geological information on earthquake recurrence and fault slip rates and by using this information in a model of the earthquake generation process. Uncertainties in both the physical basis for the model and in the geological parameters dictate a probabilistic approach. A semi-Markov model provides real-time probabilities of occurrence of at least one moderate to large (magnitude 612 or larger) earthquake at either of two sites for given elapsed times. Probabilities derived for the entire Wasatch fault zone are based on earthquake recurrence data on individual fault segments and are especially sensitive to elapsed times on individual segments.