An experimental analysis of social traps

The synaptic ribbon is a specialized structure in photoreceptor neurons that tethers vesicles prior to release (Figure ​(Figure1A).1A). When a cell is stimulated, vesicles are released from the ribbon and later replenished from the population of mobile vesicles in the synaptic terminal. A train of depolarizing pulses causes the ribbon to alternate between periods of release (lasting Δt = 25 ms) and replenishment (lasting T = 50ms), which occur on estimated timescales of τr = 5 ms (for release) and τa = 815 ms (for replenishment). After the first few pulses, the system approaches a limit cycle, and the amount of vesicles released on each pulse converges to a limiting value, R (Figure 1B). This can be used to determine the maximum available pool size on the ribbon, A. The standard method for estimating A is to measure the rate of replenishment in the limit, and then back-extrapolate from the cumulative release plot to obtain the available pool size at the start of the pulse train [1]. When comparing pulse trains of different strengths, this method yields substantially different values for A, a somewhat paradoxical result. Back-extrapolation assumes, however, that the replenishment rate is constant, even though it is thought to be proportional to the available space on the ribbon [2]. Figure 1 A) The synaptic ribbon. (B) The available pool size, A(t), during a stimulus pulse train. Table 1 Maximum pool size predictions from pulse train data We developed a model-based approach to estimate A from the limiting release R. We modeled the rate of release (resp. replenishment) to simply be proportional to the number of vesicles on the ribbon (resp. vacant ribbon sites), and using the measured timescale τr (resp. τa). By solving the alternating differential equations, we derived a recurrence relation for the release during each pulse, Ri, which we then solved to obtain a closed form expression for Ri and the limiting release R. Specifically, we found that A = cR, where c is a function of τr,τa,Δt,T, and p, with p a release constant that captures the stimulus dependence of release probabilities, and can be estimated from the first release, R1. In contrast to the back-extrapolation method, our model-based estimate for A was similar across stimulus types (Table 1), while p was much smaller for the weaker stimulus. This suggests that available pool size does not change with stimulus strength; instead, differences in release result from changes in release probability.

Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) to detect SARS-CoV-2 RNA is an essential test to monitor the occurrence of COVID-19. A methodology is proposed for the determination of maximum pool size and adjustments of cut-off values of cycle threshold ( in RT-qPCR pool testing, to compensate for the dilution caused by pooling. The trade-off between pool size and test sensitivity is stated explicitly. The procedure was designed to ensure that samples that would be detectable in individual testing remain detectable in pool testing. The proposed relaxation in cut-off is dependent on the pool size, allowing a relatively tight correction to avoid loss of detection of positive samples. The methodology was evaluated in a study of pool testing of adults attending a public emergency care unit, reference for COVID-19 in Belo Horizonte, Brazil, and presenting flu-like symptoms. Even samples on the edge of detectability in individual testing were detected correctly. The proposed procedure enhances the consistency of RT-qPCR pool testing by enforcing that the scales of detectability in pool processing and in individual sample processing are compatible. This may enhance the contribution of pool testing to large-scale testing for COVID-19.

In Chapter 3 we discussed the concepts, functions, and applications of the two discovery process models LDSCV and NDSCV. In this chapter we will use various simulated populations to validate these two models to examine whether their performance meets our expectations. In addition, lognormal assumptions are applied to Weibull and Pareto populations to assess the impact on petroleum evaluation as a result of incorrect specification of probability distributions. A mixed population of two lognormal populations and a mixed population of lognormal, Weibull, and Pareto populations were generated to test the impact of mixed populations on assessment quality. NDSCV was then applied to all these data sets to validate the performance of the models. Finally, justifications for choosing a lognormal distribution in petroleum assessments are discussed in detail. Known populations were created as follows: A finite population was generated from a random sample of size 300 (N = 300) drawn from the lognormal, Pareto, and Weibull superpopulations. For the lognormal case, a population with μ = 0 and σ2 = 5 was assumed. The truncated and shifted Pareto population with shape factor θ = 0.4, maximum pool size = 4000, and minimum pool size = 1 was created. The Weibull population with λ = 20, θ = 1.0 was generated for the current study. The first mixed population was created by mixing two lognormal populations. Parameters for population I are μ = 0, σ2 = 3, and N1 = 150. For population II, μ = 3.0, σ2 = 3.2, and N2 = 150. The second mixed population was generated by mixing lognormal (N1 = 100), Pareto (N2 = 100), and Weibull (N3 = 100) populations with a total of 300 pools. In addition, a gamma distribution was also used for reference. The lognormal distribution is J-shaped if an arithmetic scale is used for the horizontal axis, but it shows an almost symmetrical pattern when a logarithmic scale is applied.

Heating and melting of a semi-infinite body due to volumetric absorption of a moving laser radiation were studied. The problem is essentially a transient three-dimensional conduction problem with a moving heat source and a moving phase boundary. An explicit finite difference technique was used to solve for the temperature distribution and the melt pool size. In order to save computing time the solution domain was divided into inner and outer regions. The inner region was sized to contain the maximum pool size. A fine grid pattern was used for the inner region, where the temperature gradient is large and where the accurate location of the solid-liquid interface is desired. In order to validate the numerical results, comparisons were made with experimental data. The results show that the heat-affected zone and the melt pool size decrease as the translational speed of the beam increases.

A large-scale-outdoor continuous release of cryogenic liquid onto ground

Advances in nitrogen (N) saturation and retention theories have focused on soil organic matter (SOM) biogeochemistry in the absence of dynamic soil hydrology. Here we exploit two soil types with contrasting textures that span a hillslope gradient to test hypotheses that suggest N saturation symptoms are regulated by the interactive effects of soil texture, OM, and hydrology on N retention capacity (maximum pool size) and N retention kinetics (N retention rate). Down the hillslope gradient, soil solution nitrate (NO3) concentrations sampled with lysimeters increased, while 15NO3‐N retention decreased. Landscape location (upland, hillslope, and toeslope) and soil type interacted to affect soil solution NO3 concentrations so that the downslope increase in NO3 was greater in sandy versus silty soils. These patterns manifest despite a downslope increase in soil organic carbon (SOC) and C/N ratios. A positive correlation between saturated hydraulic conductivity and soil solution NO3 sampled in zero‐tension lysimeters during precipitation events suggested that high hydraulic conductivity promotes periodic rapid NO3 transport at rates that exceed retention kinetics. The downslope increase in soil solution NO3 in spite of a concomitant increase in SOC and C/N ratios provides an important contrast with previous N saturation research that highlights negative correlations between SOM C/N ratios and NO3 concentrations and suggests NO3 transport along connected hillslope flow paths may overwhelm stoichiometric sinks for inorganic N retention in SOM. Our results reveal important gaps in N retention theory based on SOM biogeochemistry alone and demonstrate how coupled biogeochemical and hydrological models can improve predictions of N saturation, particularly when considering periodic advective NO3 transport in the vadose zone. We show that in coarse‐textured soils, low capacity for protection of SOM N by association with fine mineral particles interacts with rapid hydrological flushing of NO3 to enhance the expression of ecosystem N saturation symptoms.

The scalability and performance issues about large-scale workflow are the most impeccable topics, in recent, because the size of workflow system and its applications are becoming larger and larger and requiring, nevertheless, much more reliable and faster services. These technological pressures push us to develop an EJB-based workflow management system targeting at covering these two issues, which is named e-Chautauqua. In this paper,we present an asynchronous communication mechanism|workflow message queue mechanism|providing a reliable communication channel among the constituent objects organizing the enactment engine of e-Chautauqua, and try also to measure how much the mechanism effects on accomplishing the scalable and performable e-Chautauqua. From a series of test scenarios based on the message queue properties such as message alive time and maximum pool size, we have observed that the message alive time property sensitively effects on the scalability, and while on the other the maximum pool size property has a great influence on the performance of the workflow management system.

A simple numerical model based on the shallow water equations in radial symmetry is used to simulate both instantaneous and continuous spills of liquefied natural gas (LNG) onto a water surface. Using the computed results, a study is made of the similarities and differences in the pool structure resulting from the two types of spills. For instantaneous spills a relation linear on a logarithmic plot is suggested between the maximum pool size and the spill volume. The effects of shear forces and surface cohesivity on the evolution of the spill are also examined.

The primary aim was to describe perceived exertion responses to different intensities of eccentric exercise in women and men. 42 adults (21 men and 21 women, 7 per condition) completed elbow extension exercises with a weight corresponding to 80%, 100%, or 120% of maximal voluntary concentric strength. Total work was equated by manipulating the number of repetitions in the 80% (N = 45), 100% (N = 36), and 120% (N = 30) conditions. A two-way ANOVA showed significant main effects for the intensity and sex factors. Perceived exertion ratings were strongly dependent on exercise intensity, and women reported lower RPEs than men. A separate three-way mixed model ANOVA that included a repetition factor showed that perceived exertion ratings increased similarly across the first 30 repetitions in all exercise conditions. Significant partial correlations were found between mean RPE during the eccentric exercise bout, and the mean intensity of delayed-onset muscle pain measured from 12- to 72-h postexercise after controlling for the relative exercise intensity (r12.3 = 0.28) or the maximum concentric strength of the elbow flexors (r12.3 = 0.33). 1) for both women and men, there is a positive association between the intensity of eccentric exercise performed with the elbow flexors and RPE; 2) perceived exertion ratings increase significantly then plateau when repeated eccentric muscle actions are performed at constant, submaximal absolute intensities; 3) women rate eccentric exercise performed at the same intensity (relativized to MVC-C) as being less effortful compared with men; and 4) RPE during eccentric exercise can account for a small but significant amount of variability in delayed-onset muscle pain after statistically controlling for differences in strength or relative intensity.

The hepatic transport of bile salts appears to be adaptively regulated by changes in the bile salt pool size and in the flux of bile salt through the liver. The maximum secretory rate of taurocholate increases or decreases when the bile salt pool size is modified by either oral feeding of cholate or taurocholate (up-regulation) or prolonged bile salt depletion through a biliary fistula (down-regulation), respectively. It is not known whether adaptive regulation of hepatic bile salt transport operates under conditions in which the bile salt pool size is modified by endogenous changes in bile acid metabolism. Because experimental diabetes mellitus is associated with alterations in the synthesis of bile acids and total bile salt pool size and composition in the rat, we examined the effects of diabetes mellitus induced by alloxan (5 mg/100 gm body weight, intravenously) and insulin treatment on hepatic bile salt transport and relate the changes to bile salt pool size variations. At 3 days after alloxan injection (DIAB-3 group) both taurocholate maximum secretory rate and pool size were significantly decreased, whereas they were restored to normal values after 6 days of diabetes (DIAB-6 group). Insulinopenic diabetes for 14 days (DIAB-14 group) and for 24 days (DIAB-24 group) resulted in a marked increase of basal bile salt secretory rate (secondary to an increased contribution of cholate conjugates) and an enhanced taurocholate maximum secretory rate compared with control rats (147% and 188% increase, respectively) and with a group (PHARM-control) that received alloxan but did not develop detectable glycosuria (224% and 286% increase, respectively). In contrast, sulfobromophthalein maximum secretory rate was not significantly modified in 14-day diabetic rats compared with control rats. In addition, diabetic rats demonstrated a significant reduction of the bile salt-independent fraction of bile flow. Insulin treatment (3 units/100 gm body wt/day) in diabetic rats from day 0 (alloxan injection) to day 14 (INS-14 group) and from day 14 to day 24 after alloxan administration (INS-24 group) normalized basal bile salt secretion, taurocholate maximum secretory rate and the bile salt-independent fraction of bile flow. Bile salt pool size was significantly greater in DIAB-14 and DIAB-24 groups than in the control group (172% and 216% greater, respectively) and the PHARM-control group (246% and 309% greater, respectively). Insulin treatment prevented, in the INS-14 group, and reversed, in the INS-24 group, the increase of bile salt pool. Cholestyramine administration (5% wt/wt in the diet) to diabetic rats from day 0 (alloxan injection) to day 14 (CHOL-14 group) and from day 14 to day 24 after alloxan administration (CHOL-24 group) prevented and reversed, respectively, bile salt pool and taurocholate maximum secretory rate increase without modifying the hyperglycemia. In conclusion, alloxan diabetes brings about marked changes in taurocholate maximum secretory rate, that appear to be selective, because sulfobromophthalein maximum secretory rate is unaltered. Both enhanced and decreased taurocholate maximum secretory rate appear to be primarily related to, and follow, parallel changes in bile salt (cholate) pool size induced by diabetes. Both insulin and cholestyramine can prevent and reverse the enhancement of taurocholate maximum secretory rate induced by diabetes. Thus changes in taurocholate maximum secretory rate in this experimental model probably represent an adaptive response to increased hepatic bile salt load, supporting the concept that bile salt pool size is an important factor in the down-regulation and up-regulation of hepatic bile salt transport. (Hepatology 1991;14:671-678.)

The hepatic transport of bile salts appears to be adaptively regulated by changes in the bile salt pool size and in the flux of bile salt through the liver. The maximum secretory rate of taurocholate increases or decreases when the bile salt pool size is modified by either oral feeding of cholate or taurocholate (up-regulation) or prolonged bile salt depletion through a biliary fistula (down-regulation), respectively. It is not known whether adaptive regulation of hepatic bile salt transport operates under conditions in which the bile salt pool size is modified by endogenous changes in bile acid metabolism. Because experimental diabetes mellitus is associated with alterations in the synthesis of bile acids and total bile salt pool size and composition in the rat, we examined the effects of diabetes mellitus induced by alloxan (5 mg/100 gm body weight, intravenously) and insulin treatment on hepatic bile salt transport and relate the changes to bile salt pool size variations. At 3 days after alloxan injection (DIAB-3 group) both taurocholate maximum secretory rate and pool size were significantly decreased, whereas they were restored to normal values after 6 days of diabetes (DIAB-6 group). Insulinopenic diabetes for 14 days (DIAB-14 group) and for 24 days (DIAB-24 group) resulted in a marked increase of basal bile salt secretory rate (secondary to an increased contribution of cholate conjugates) and an enhanced taurocholate maximum secretory rate compared with control rats (147% and 188% increase, respectively) and with a group (PHARM-control) that received alloxan but did not develop detectable glycosuria (224% and 286% increase, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

How vesicular dynamics parameters depend on temperature and how temperature affects the parameter change during prolonged high frequency stimulation was determined by fitting a model of vesicular storage and release to the amplitudes of the excitatory post-synaptic currents (EPSC) recorded from CA1 neurons in rat hippocampal slices. The temperature ranged from low (13°C) to higher and more physiological temperature (34°C). Fitting the model of vesicular storage and release to the EPSC amplitudes during a single pair of brief high-low frequency stimulation trains yields the estimates of all parameters of the vesicular dynamics, and with good precision. Both fractional release and replenishment rate decrease as the temperature rises. Change of the underlying 'basic' parameters (release coupling, replenishment coupling and readily releasable pool size), which the model-fitting also yields is complex. The replenishment coupling between the readily releasable pool (RRP) and resting pool increases with temperature (which renders the replenishment rate higher), but this is more than counterbalanced by greater RRP size (which renders the replenishment rate lower). Finally, during long, high frequency patterned stimulation that leads to significant synaptic depression, the replenishment rate decreases markedly and rapidly at low temperatures (<22°C), but at high temperatures (>28°C) the replenishment rate rises with stimulation, making synapses better able to maintain synaptic efficacy.

The prediction of the flow behavior of Metal micro-molten pool is prerequisite for high-quality Laser Powder Bed Fusion (L-PBF). In this study, mesoscopic scale numerical simulation modelling for L-PBF process was used to help understand the melting process of pure copper micro-melt pool. In this study, the orthogonal test was designed to study the influence of laser power, laser scanning velocity, hatching space on the flow behavior of molten pool and the overlapping rate of adjacent molten tracks. The results shows that laser scanning speed has the greatest influence on both the size and overlapping rate of the molten pool, and the overall trend was that the size of molten pool continues to increase as the volume energy density increases, and the maximum molten pool size was 243.6 um × 110 um with volume energy density 370.037 J mm−3, overlapping rate of adjacent molten tracks was 48.84% with volume energy density 285.71 J/mm3. The optimized pure copper laser process parameters were obtained: laser power 300 KW, laser scanning speed 500 mm/s, hatching space 0.07 mm, overlapping rate 48.84%.

Human-induced environmental and climate change are widely blamed for causing rapid global biodiversity loss, but direct estimation of the proportion of biodiversity lost at local or regional scales are still infrequent. This prevents us from quantifying the main and interactive effects of anthropogenic environmental and climate change on species loss. Here, we demonstrate that the estimated proportion of species loss of 252 key protected vertebrate species at a county level of China during the past half century was 27.2% for all taxa, 47.7% for mammals, 28.8% for amphibians and reptiles and 19.8% for birds. Both human population increase and species richness showed significant positive correlations with species loss of all taxa combined, mammals, birds, and amphibians and reptiles. Temperature increase was positively correlated with all-taxa and bird species loss. Precipitation increase was negatively correlated with species loss of birds. Human population change and species richness showed more significant interactions with the other correlates of species loss. High species richness regions had higher species loss under the drivers of human environmental and climate change than low-richness regions. Consequently, ongoing human environmental and climate changes are expected to perpetuate more negative effects on the survival of key vertebrate species, particularly in high-biodiversity regions.

Fossil records generally inform paleobiologists about extinct taxa and rates of evolution measured at the scale of millions of years. Good records that are densely sampled through time can reveal species level details such as longevity in local sections. Yet fossil data normally do not address details of lineage microevolution because the density through time of lineage sampling is insufficient to perceive patterns at a precision finer than 106years in most cases. This study concerns details of a splitting event in the evolution of murine rodents, an event for which multiple fossil samples dated to a precision of 105years fortuitously document the tempo and mode of origin of sister species, the stems of two extant tribes of mice. Evolution of early Murinae in the northern part of the biogeographically restricted Indian subcontinent between 11.6 and 10.5 Ma involved cladogenesis of two crown taxa, the extant tribes Murini and Arvicanthini. Large samples of fossil rodent teeth document their divergence from a common morphological pool. Definitive basal Murini and Arvicanthini at 10.5 Ma are similar in size and differ by subtle features of the dentition. Those features occur sporadically in the common pool of older fossil teeth at 11.2, 11.4, and 11.6 Ma as inconsistent polymorphisms. Interpreted as a single lineage in the 11.6–11.2 Ma interval, variability of this abundant murine incorporated the roots of the two crown tribes. The pattern through time suggests morphological stasis for several hundred thousand years prior to splitting. This special case informs us on one example of evolution and shows that the tempo of splitting evolution in some cases may be measured in hundreds of thousands of years, followed by stasis once daughter species have differentiated morphologically.