Number Of Solicitations Research Articles

On the mean time to failure of an age-replacement model in discrete time

Industrial feedback data play a key role in assessing and enhancing reliability of the operating systems or equipment. In case of equipment that operates on cycles or on demand, lifetime is measured in number of cycles or number of solicitations before its failure. These situations suggest the use of discrete probability models. In this article, we look into the maintenance aspect of these equipments. In particular, we consider the discrete age-replacement model and then study the properties of the mean time to failure (MTTF) of a system. Using MTTF, we have established some characterizations. An ordering based on MTTF is developed and its implications on other existing stochastic orders are investigated. Finally, we propose a simple non parametric test for testing decreasing MTTF class.

Learning by fund-raising

From experience, fund-raisers become more efficient solicitors. This paper offers a full characterization of the optimal solicitation strategy when there are learning economies. The characterization is recursive, and does not require equilibrium computations. Our main results are that (1) the fund-raiser may now solicit a “ net free-rider”—a donor whose contribution falls below the marginal solicitation cost; (2) the number of solicitations is non-monotonic in the learning rate; and (3) a solicitation technology with high overhead but low marginal costs is likely to be optimal if income distribution in the population is relatively homogenous. The complementary case with a decreasing returns to scale technology is also considered.

Determination of Red Blood Cell fatigue using electrodeformation.

In this work, we used electrodeformation (ED) [1] as a new strategy to evaluate the fatigue of healthy human Red Blood Cells (RBCs). Using dielectrophoresis (DEP) forces, we submitted RBCs to a series of elongation and relaxation cycles to model their mechanical stress in the blood circulation and we used their relaxation time as a marker to evaluate their fatigue. In this paper, we first investigated the dependency of the RBC mechanical response upon the experimental parameters, such as the viscosity ηout of the external medium, the amplitude ΔV of the applied voltage, the duration of the solicitation tsol, the number of solicitations N as well as the resting time trest between two solicitations. The impact of these parameters was evaluated through the analysis of both RBC deformation index D and relaxation time τ. Finally, the optimization of these parameters was used to monitor RBC fatigue.

CONFIGURATIONS OF TIRE PRESSURE ON THE PAVEMENT FOR COMMERCIAL VEHICLES: CALCULATION OF THE ‘N’ NUMBER AND THE CONSEQUENCES ON PAVEMENT PERFORMANCE

Road traffic has a high variety of types of vehicles and cargo transported. One of the main difficulties in pavement design is forecasting the changes in traffic over time and evaluating the comparative deterioration power of the various loads with axle and tire settings and different levels of repetition. The road environment in Brazil, as we know, is the main means of the country's cargo transportation. Throughout the 1990s and 2000s the road modal accounted for over 60% of the total cargo transported in the country leaving the unbalanced Brazilian transport matrix with almost exclusive investments in such means of transportation. According to CNT 2012, which conducted a survey in approximately 45% of the paved network, evaluating the pavement functional conditions, traffic signs and geometry, 46% of the country’s road network has some type of deficiency in the pavement. The goal of this work is to contribute to a better understanding of the complex influence of traffic in the design and service life of the pavement. The load pressure of commercial vehicle tires over the pavement has increased in recent decades. A more apparent effect of this increase in tire pressure would be the change in the pavement- tire contact area which in turn may result in an increase in the contact load between tire and pavement and other harmful effects on the structure. This study aims to determine the effect on the calculation of the N number, or the number of solicitations of the standard axle on the road pavement, measuring the overload as a percentage of the legal load indicated by a scale. In short, we calculate how an increase in the overload percentage in comparison with the allowable load will influence the decrease of the calculated durability of the pavement designed for the highway.

On the Practical Interest of Discrete Inverse Pólya and Weibull‐1 Models in Industrial Reliability Studies

Engineers often cope with the problem of assessing the lifetime of industrial components, on the basis of observed industrial feedback data. Usually, lifetime is modelled as a continuous random variable, for instance, exponentially or Weibull distributed. However, in some cases, the features of the piece of equipment under investigation rather suggest the use of discrete probabilistic models. This happens for equipment that only operates on cycles or on demand. In these cases, the lifetime is rather measured in number of cycles or number of solicitations before failure; therefore, in theory, discrete models should be more appropriate. This article aims at bringing some light to the practical interest of the reliability engineer in using two discrete models among the most popular: the inverse Pólya distribution (IPD), based on a Pólya urn scheme, and the so‐called Weibull‐1 model. It is shown that for different reasons, the practical use of both models should be restricted to specific industrial situations. In particular, when nothing is a priori known over the nature of ageing and/or data are heavily right censored, they can remain of limited interest with respect to more flexible continuous lifetime models such as the usual (continuous) Weibull distribution. Nonetheless, the intuitive meaning given to the IPD could favour its use by engineers in low (decelerated) ageing situations. Copyright © 2015 John Wiley & Sons, Ltd.

Clitoral anesthesia disrupts paced copulation in the female rat

Clitoral stimulation produced by sexual contact with a partner or during manual stimulation is associated with pleasure in humans, and produces conditioned place preference in rats. The present experiment investigated the effect of blocking genitosensory stimulation of the clitoris with lidocaine during copulation in female rats on a measure of female sexual motivation: pacing behavior. Sexually naïve, ovariectomized female rats were treated with 10μg estradiol benzoate 48h and 500μg progesterone 4h prior to a 30-min copulatory trial with a sexually vigorous stimulus male scheduled every 4days. A total of 10 copulatory sessions were divided into two phases of 5 trails each. In the first phase, females received an injection (0.05ml) of either 2% lidocaine, saline, or no injection to the clitoral sheath under isoflurane anesthesia immediately prior to the start of a copulatory session, and were then placed on one side of a paced mating chamber and allowed to copulate for 30min. In the second phase, females previously injected with lidocaine were switched to saline and vice versa, and the no injection group remained the same. Variables measured included overall time spent with the males, number of solicitations, contact–return latencies following male mounts, intromissions, and ejaculations; the frequency of entrances and exits from the male chamber, and frequency of mounts, intromissions, ejaculations. Sexual behavior was examined at session 1, session 5, and session 10. At test 5, females that received LID had a greater number of entrances/exits but spent significantly less time in the presence of the male during the copulatory bout than CNTL animals. These females also displayed a trend for longer contact return latencies s after ejaculations than VEH and CNTL groups. On session 10, females that received LID and subsequently switched to VEH treatment no longer differed from controls in entrance/exit numbers, time spent with males or ejaculation contact return latency. They did however, receive a greater number of intromissions and displayed shorter inter intromission intervals compared to CNTLs. We suggest that clitoral stimulation in the rat serves as both a reward signal and may contribute to the detection of differences in copulatory stimuli that are critical to pacing and potentially, the initiation of pregnancy.

P.1.d.012 Conditioned place aversion induced by different neuroleptics in mice: an animal model to predict adherence to treatment

Clitoral stimulation produced by sexual contact with a partner or during manual stimulation is associated with pleasure in humans, and produces conditioned place preference in rats. The present experiment investigated the effect of blocking genitosensory stimulation of the clitoris with lidocaine during copulation in female rats on a measure of female sexual motivation: pacing behavior. Sexually naïve, ovariectomized female rats were treated with 10 μg estradiol benzoate 48 h and 500 μg progesterone 4 h prior to a 30-min copulatory trial with a sexually vigorous stimulus male scheduled every 4 days. A total of 10 copulatory sessions were divided into two phases of 5 trails each. In the first phase, females received an injection (0.05 ml) of either 2% lidocaine, saline, or no injection to the clitoral sheath under isoflurane anesthesia immediately prior to the start of a copulatory session, and were then placed on one side of a paced mating chamber and allowed to copulate for 30 min. In the second phase, females previously injected with lidocaine were switched to saline and vice versa, and the no injection group remained the same. Variables measured included overall time spent with the males, number of solicitations, contact–return latencies following male mounts, intromissions, and ejaculations; the frequency of entrances and exits from the male chamber, and frequency of mounts, intromissions, ejaculations. Sexual behavior was examined at session 1, session 5, and session 10. At test 5, females that received LID had a greater number of entrances/exits but spent significantly less time in the presence of the male during the copulatory bout than CNTL animals. These females also displayed a trend for longer contact return latencies s after ejaculations than VEH and CNTL groups. On session 10, females that received LID and subsequently switched to VEH treatment no longer differed from controls in entrance/exit numbers, time spent with males or ejaculation contact return latency. They did however, receive a greater number of intromissions and displayed shorter inter intromission intervals compared to CNTLs. We suggest that clitoral stimulation in the rat serves as both a reward signal and may contribute to the detection of differences in copulatory stimuli that are critical to pacing and potentially, the initiation of pregnancy.

A Theory of the Risks of Venture Capital Financing

Problem statement: There is no general theory analyzing how the time-varying cash flows of venture capitalist financing affect the likelihood of success of a new venture. This research addressed that lacuna in the literature. Approach: Research in the area of venture capital financing was needed because of the importance of new ventures as germinators of technological innovation. The research in this study developed a general economic theory quantifying the risk of venture failure associated with time-varying cash flows of financing. Each occasion when an entrepreneur made an overture to a venture capitalist to elicit a financing commitment was defined to be a distinct "solicitation event". The series of financial commitments elicited from venture capitalists were assumed to have the characteristics of independently distributed random variables. It was assumed that the entrepreneur must secure a minimal aggregate commitment in order to ensure development of the project; failure to secure that amount caused the venture to be aborted. The theory of stochastic processes was applied to derive the practical implications as regards the risk of abortion. Results: It was shown that the aggregate financing commitment secured by an entrepreneur in a finite time had stochastic properties corresponding to those of a statistical renewal process. The research derived limiting conditions on the probability that entrepreneur’s venture will be aborted because of his failure to secure the minimal aggregate commitment. The main result was that if the number of solicitations by the entrepreneur is large and the financial commitments were independently distributed random variables with finite means and variances, the probability distribution governing venture survival is the Normal distribution. Conclusion: The study derived four analytical propositions quantifying the trade-offs between the risk and the expected return associated with venture capital financing. The policy implications of the results imply the benefits of mitigating information asymmetry. Some of the risk faced by the entrepreneurs could be attenuated if information about the risk/return preferences of venture capitalists were known to the entrepreneurs prior to solicitation. Some of the risks faced by the venture capitalists could be attenuated if information about the risk/return characteristics of the proposed investment project could be accurately and transparently communicated to the venture capitalist during the solicitation event. If either or both of these information deficits were palliated, the market for venture capital would operate more efficiently.

Debunking the Commercial Profilers' Claims: A Skeptical Analysis of the Benefits of Personal Information Flows

In comments to the Federal Trade Commission, the authors propose a model for evaluating the costs to personal privacy imposed by uses of personal information. Under this proposal, the costs of information flows would be measured against Fair Information Practices, principles that set out the rights and responsibilities of data subjects and data collectors. The authors argue that many economic assumptions regarding the benefits of information flows have not come to fruition, especially in the financial services arena. The authors challenge five specious claims of the information industry: that information flows reduce prices, that customers want personalization, that profiling reduces the number of solicitations that individuals receive; that personal information allows companies to extend consumers more choices, and that information flows reduce fraud.

Social Interactions and Familiarity in a Communal Halictine Bee Lasioglossum (Chilalictus) hemichalceum

AbstractSocial organization in Hymenoptera is quite variable, but most group‐living species have a reproductive division of labor. Communal species, by definition, do not; all individuals work and all are reproductive. In order to understand the evolution and maintenance of such cooperative societies the essential first step is characterization of the behavioral interactions between individuals. In particular, it is important to investigate the influence of common group membership (familiarity) on these interactions.Circle‐tube arenas were used to observe the interactions between 42 pairs of field‐collected Lasioglossum (Chilalictus) hemichalceum females either from the same nest, from different nests but the same nest aggregation, or from different aggregations. Identical procedures were applied to 24 pairs of females from laboratory colonies. There was a striking lack of agonistic behavior with Lunging occurring in only 0.03% of all bouts, and C‐Postures (threat behavior) in only 19% of bouts using field bees and 27 % of bouts using females held in the laboratory. Passing was virtually ubiquitous, occurring in 98 % of all bouts. None of these behavior patterns is significantly associated with the level of familiarity between females. The lack of agonistic behavior and the indiscriminate cooperative behavior (Passing) suggest that all conspecifics are accepted and are treated similarly. This is in contrast to previous studies of L. (Dialictus) zephyrum that demonstrated both kin recognition and nepotism.While Avoidance behavior was rare, significantly more was seen between bees taken from different nest aggregations. Trophallaxis Solicitation occurred in 13 bouts between field bees. While the proportion of bouts in which this occurred is not associated with familiarity, the number of solicitations per bout is greater between females from different nest aggregations. These minor but statistically significant differences suggest that L. hemichalceum females can discriminate between familiar and unfamiliar individuals.Therefore the proximate mechanism underlying universal acceptance of all conspecifics cannot be a lack of recognition cue expression or recognition cue perception. Rather, it is due to a lack of clearly preferential treatment toward familiar individuals. This suggests that some component of fitness is positively associated with group membership per se, or group size.The high levels of mutual tolerance suggest, as do other lines of evidence (Kukuk & Schwarz 1987), that communal societies are not intermediate between solitary and eusocial species.