Ready and Waiting: Delayed Hatching and Extended Incubation of Anamniotic Vertebrate Terrestrial Eggs

Some anamniotic aquatic vertebrates lay eggs in a terrestrialhabitat that is hostile to the survival of hatchings or larvae.These terrestrial eggs are ready and able to hatch at a particulardevelopmental time, but do not hatch until presented with suitableconditions for aquatic larval survival. Beyond this time, hatchingis possible whenever aquatic conditions occur. The durationof extended terrestrial incubation is dependent on the availabilityof energy for metabolism from the yolk. Extended incubationis useful for anamniotic eggs laid in terrestrial habitats whereconditions suitable for larval survival arrive with unpredictableor variable timing. Examples of anamniotes with delayed hatchingand extended terrestrial incubation can be found among teleostfishes, anurans, and caudate amphibians. This paper characterizesthe embryonic period, compares this mode with other forms ofdevelopmental plasticity in anamniotes, evaluates the constraintsand advantages of this life history mode, and examines how somefishes and amphibians are able to obtain the benefits of terrestrialityfor their eggs when the timing of the return to aquatic conditionsis not entirely predictable.     

Medical Team Evaluation: Effect on Emergency Department Waiting Time and Length of Stay

Emergency Departments (ED) are trying to alleviate crowding using various interventions. We assessed the effect of an alternative model of care, the Medical Team Evaluation (MTE) concept, encompassing team triage, quick registration, redesign of triage rooms and electronic medical records (EMR) on door-to-doctor (waiting) time and ED length of stay (LOS). We conducted an observational, before-and-after study at an urban academic tertiary care centre. On July 17^th 2014, MTE was initiated from 9:00 a.m. to 10 p.m., 7 days a week. A registered triage nurse was teamed with an additional senior ED physician. Data of the 5-month pre-MTE and the 5-month MTE period were analysed. A matched comparison of waiting times and ED LOS of discharged and admitted patients pertaining to various Emergency Severity Index (ESI) triage categories was performed based on propensity scores. With MTE, the median waiting times improved from 41.2 (24.8–66.6) to 10.2 (5.7–18.1) minutes (min; P < 0.01). Though being beneficial for all strata, the improvement was somewhat greater for discharged, than for admitted patients. With a reduction from 54.3 (34.2–84.7) to 10.5 (5.9–18.4) min (P < 0.01), in terms of waiting times, MTE was most advantageous for ESI4 patients. The overall median ED LOS increased for about 15 min (P < 0.01), increasing from 3.4 (2.1–5.3) to 3.7 (2.3–5.6) hours. A significant increase was observed for all the strata, except for ESI5 patients. Their median ED LOS dropped by 73% from 1.2 (0.8–1.8) to 0.3 (0.2–0.5) hours (P < 0.01). In the same period the total orders for diagnostic radiology increased by 1,178 (11%) from 10,924 to 12,102 orders, with more imaging tests being ordered for ESI 2, 3 and 4 patients. Despite improved waiting times a decrease of ED LOS was only seen in ESI level 5 patients, whereas in all the other strata ED LOS increased. We speculate that this was brought about by the tendency of triage physicians to order more diagnostic radiology, anticipating that it may be better for the downstream physician to have more information rather than less.     

Waiting with and without Recombination: The Time to Production of a Double Mutant

R. A. Fisher and H. J. Muller argued in the 1930s that a major evolutionary advantage of recombination is that it allows favorable mutations to be combined within an individual even when they first appear in different individuals. This effect is evaluated in a two-locus, two-allele model by calculating the average waiting time until a new genotypic combination first appears in a haploid population. Three approximations are developed and compared with Monte Carlo simulations of the Wright–Fisher process of random genetic drift in a finite population. First, a crude method, based on the deterministic accumulation of single mutants, produces a waiting time of 1/with no recombination and 1/with recombination between the two loci, whereμis the mutation rate,Nis the haploid population size, andRis the recombination rate. Second, the waiting time is calculated as the expected value of a heterogeneous geometric distribution obtained from a branching process approximation. This gives accurate estimates forNμlarge. The estimates for small values ofNμare considerably lower than the simulated values. Finally, diffusion analysis of the Wright–Fisher process provides accurate estimates forNμsmall, and the time scales of the diffusion process show a difference betweenR=0 and forR?0 of the same order of magnitude as seen in the deterministic analysis. In the absence of recombination, accurate approximations to the waiting time are obtained by using the branching process for highNμand the diffusion approximation for lowNμ. For lowNμthe waiting time is well approximated by 1/. WithR?0, the following dependence onNμis observed: ForNμ>1 the waiting time is virtually independent of recombination and is well described by the branching process approximation. ForNμ≈ the waiting time is well described by a simplified diffusion approximation that assumes symmetry in the frequencies of single mutants. ForNμ?1 the waiting time is well described by the diffusion approximation allowing asymmetry in the frequencies of single mutants. Recombination lowers the waiting time until a new genotypic combination first appears, but the effect is small compared to that of the mutation rate and population size. For largeNμ, recombination has a negligible effect, and its effect is strongest for smallNμ, in which case the waiting time approaches a fixed fraction of the waiting time forR=0. Free recombination lowers the waiting time to about 45% of the waiting time for absolute linkage for smallNμ. Selection has little effect on the importance of recombination in general.     

Delay and Probability Discounting of Sexual and Monetary Outcomes in Individuals with Cocaine Use Disorders and Matched Controls

Individuals with cocaine use disorders are disproportionately affected by HIV/AIDS, partly due to higher rates of unprotected sex. Recent research suggests delay discounting of condom use is a factor in sexual HIV risk. Delay discounting is a behavioral economic concept describing how delaying an event reduces that event’s value or impact on behavior. Probability discounting is a related concept describing how the uncertainty of an event decreases its impact on behavior. Individuals with cocaine use disorders (n = 23) and matched non-cocaine-using controls (n = 24) were compared in decision-making tasks involving hypothetical outcomes: delay discounting of condom-protected sex (Sexual Delay Discounting Task), delay discounting of money, the effect of sexually transmitted infection (STI) risk on likelihood of condom use (Sexual Probability Discounting Task), and probability discounting of money. The Cocaine group discounted delayed condom-protected sex (i.e., were more likely to have unprotected sex vs. wait for a condom) significantly more than controls in two of four Sexual Delay Discounting Task partner conditions. The Cocaine group also discounted delayed money (i.e., preferred smaller immediate amounts over larger delayed amounts) significantly more than controls. In the Sexual Probability Discounting Task, both groups showed sensitivity to STI risk, however the groups did not differ. The Cocaine group did not consistently discount probabilistic money more or less than controls. Steeper discounting of delayed, but not probabilistic, sexual outcomes may contribute to greater rates of sexual HIV risk among individuals with cocaine use disorders. Probability discounting of sexual outcomes may contribute to risk of unprotected sex in both groups. Correlations showed sexual and monetary results were unrelated, for both delay and probability discounting. The results highlight the importance of studying specific behavioral processes (e.g., delay and probability discounting) with respect to specific outcomes (e.g., monetary and sexual) to understand decision making in problematic behavior.     

时滞传染病模型的指数稳定性

利用分析技巧研究了一类SEIRS传染病模型的动力学行为.结论表明如果再生数小于1,则带变时滞的传染病模型的无病平衡点是全局指数渐近稳定的,如果再生数大于1,得到传染病平衡点局部指数稳定的充分条件,同时给出了例子说明结论的有效性.     

Corticosteroids and Pediatric Septic Shock Outcomes: A Risk Stratified Analysis

Background

The potential benefits of corticosteroids for septic shock may depend on initial mortality risk.

Objective

We determined associations between corticosteroids and outcomes in children with septic shock who were stratified by initial mortality risk.

Methods

We conducted a retrospective analysis of an ongoing, multi-center pediatric septic shock clinical and biological database. Using a validated biomarker-based stratification tool (PERSEVERE), 496 subjects were stratified into three initial mortality risk strata (low, intermediate, and high). Subjects receiving corticosteroids during the initial 7 days of admission (n = 252) were compared to subjects who did not receive corticosteroids (n = 244). Logistic regression was used to model the effects of corticosteroids on 28-day mortality and complicated course, defined as death within 28 days or persistence of two or more organ failures at 7 days.

Results

Subjects who received corticosteroids had greater organ failure burden, higher illness severity, higher mortality, and a greater requirement for vasoactive medications, compared to subjects who did not receive corticosteroids. PERSEVERE-based mortality risk did not differ between the two groups. For the entire cohort, corticosteroids were associated with increased risk of mortality (OR 2.3, 95% CI 1.3–4.0, p = 0.004) and a complicated course (OR 1.7, 95% CI 1.1–2.5, p = 0.012). Within each PERSEVERE-based stratum, corticosteroid administration was not associated with improved outcomes. Similarly, corticosteroid administration was not associated with improved outcomes among patients with no comorbidities, nor in groups of patients stratified by PRISM.

Conclusions

Risk stratified analysis failed to demonstrate any benefit from corticosteroids in this pediatric septic shock cohort.     

具有时滞的细胞神经网络模型的全局指数稳定性

利用拓扑度理论、推广的Halanaly矩阵时滞微分不等式、Lyapunov原理以及Dini导数,研究了具有时滞的细胞神经网络模型的全局指数稳定性．去掉了有关文献中要求输出函数fj在实数集R上有界、可微的条件,给出了更弱的判定平衡点的存在唯一性以及全局指数稳定性的判据,推广和改进了前人的相关结论,最后的数值例子说明本文结果不仅保守性小,而且计算简单．     

Joint Analysis of Survival Time and Longitudinal Categorical Outcomes

In biomedical or public health research, it is common for both survival time and longitudinal categorical outcomes to be collected for a subject, along with the subject’s characteristics or risk factors. Investigators are often interested in finding important variables for predicting both survival time and longitudinal outcomes which could be correlated within the same subject. Existing approaches for such joint analyses deal with continuous longitudinal outcomes. New statistical methods need to be developed for categorical longitudinal outcomes. We propose to simultaneously model the survival time with a stratified Cox proportional hazards model and the longitudinal categorical outcomes with a generalized linear mixed model. Random effects are introduced to account for the dependence between survival time and longitudinal outcomes due to unobserved factors. The Expectation–Maximization (EM) algorithm is used to derive the point estimates for the model parameters, and the observed information matrix is adopted to estimate their asymptotic variances. Asymptotic properties for our proposed maximum likelihood estimators are established using the theory of empirical processes. The method is demonstrated to perform well in finite samples via simulation studies. We illustrate our approach with data from the Carolina Head and Neck Cancer Study (CHANCE) and compare the results based on our simultaneous analysis and the separately conducted analyses using the generalized linear mixed model and the Cox proportional hazards model. Our proposed method identifies more predictors than by separate analyses.     

Calculation of Km and Vmax from Substrate Concentration Versus Time Plot

A simple method for the calculation of kinetic parameters (K_m, V_max) under conditions of changing substrate concentrations is presented. An application of the method to detect shifts in groups involved in the utilization of a substrate in a mixed microbial culture is given.     

Inflammatory Bowel Disease and Risk of Adverse Pregnancy Outcomes

Background and Objectives

Existing data on pregnancy complications in inflammatory bowel disease (IBD) are inconsistent. To address these inconsistencies, we investigated potential associations between IBD, IBD-related medication use during pregnancy, and pregnancy loss, pre-eclampsia, preterm delivery, Apgar score, and congenital abnormalities.

Methods

We conducted a cohort study in >85,000 Danish National Birth Cohort women who were pregnant in the period 1996-2002 and had information on IBD, IBD-related medication use (systemic or local corticosteroids, 5-aminosalicylates), pregnancy outcomes and potential confounders. We evaluated associations between IBD and adverse pregnancy/birth outcomes using Cox regression and log-linear binomial regression.

Results

IBD was strongly and significantly associated with severe pre-eclampsia, preterm premature rupture of membranes and medically indicated preterm delivery in women using systemic corticosteroids during pregnancy (hazard ratios [HRs] >7). IBD was also associated with premature preterm rupture of membranes in women using local corticosteroid medications (HR 3.30, 95% confidence interval [CI] 1.33-8.20) and with medically indicated preterm delivery (HR 1.91, 95% CI 0.99-3.68) in non-medicated women. Furthermore, IBD was associated with low 5-minute Apgar score in term infants (risk ratio [RR] 2.19, 95% CI 1.03-4.66). Finally, Crohn’s disease (but not ulcerative colitis) was associated with major congenital abnormalities in the offspring (RR 1.85, 95% CI 1.06-3.21). No child with a congenital abnormality born to a woman with IBD was exposed to systemic corticosteroids in utero.

Conclusion

Women with IBD are at increased risk of severe pre-eclampsia, medically indicated preterm delivery, preterm premature rupture of membranes, and delivering infants with low Apgar score and major congenital malformations. These associations are only partly explained by severe disease as reflected by systemic corticosteroid use.     

Beyond Mean and Variance: Economic Risk Versus Perceived Risk of Farming, Foraging, and Fishing Activities in Southwestern Madagascar

Economic analyses of risk typically employ mean and variance calculations such as the coefficient of variation (CV) and z-score model. In this study we examine to what degree these simple measures approximate people’s perceptions of the risk associated with different farming, foraging, and fishing subsistence activities in southwestern Madagascar. CV calculated using production data for 15 activities (ranked) explains about 18 % of participants’ risk ratings from 24 focus groups. CV corresponds better to the ratings of men (37 %) and farmers (40 %), but does not predict the ratings by women, foragers, or Vezo fishermen, suggesting that economic measures of risk have a male and agrarian bias. Narrative responses suggest that risk is qualitatively different for foragers and fishermen, who face hazard (danger) and the cosmological dread of dying far from home. We conclude by predicting the ethnographic and ecological contexts when researchers should go beyond mean and variance when estimating risk.     

The Delayed Risk Stratification System in the Risk of Differentiated Thyroid Cancer Recurrence

ContextThere has been a marked increase in the detection of differentiated thyroid carcinoma (DTC) over the past few years, which has improved the prognosis. However, it is necessary to adjust treatment and monitoring strategies relative to the risk of an unfavourable disease course.ResultsThe PPV and NPV for the ATA (24.59% and 95.42%, respectively) and ETA (24.28% and 95.68%, respectively) were significantly lower than those for the DRS (56.76% and 98.5%, respectively) (p<0.0001). The proportion of variance for predicting the final outcome was 15.8% for ATA, 16.1% for ETA and 56.7% for the DRS. Recurrent disease was rare (1% of patients), and was nearly always identified in patients at intermediate/high risk according to the initial stratification (9/10 cases).ConclusionsThe DRS showed a better correlation with the risk of persistent disease than the early stratification systems and allows personalisation of follow-up. If clinicians plan to alter the intensity of surveillance, patients at intermediate/high risk according to the early stratification systems should remain within the specialized centers; however, low risk patients can be referred to endocrinologists or other appropriate practitioners for long-term follow-up, as these patients remained at low risk after risk re-stratification.     

Psychosocial Predictors and Outcomes of Delayed Breast Reconstruction in Mastectomized Women in Mainland China: An Observational Study

Background

The aim of the present study was to evaluate potential psychosocial factors that impact Chinese female breast cancer patients to select breast reconstruction (BR), and potential connection of psychosocial outcomes with their satisfaction with BR.

Methods

A total of 264 female breast cancer patients with mastectomy were recruited from 2012 to 2014. All patients were informed with BR options at their first visit. Personal and medical profiles were collected. Body image, self-esteem, depression and anxiety were assessed using validated scales. Patients who were selected to undergo BR after the first visit were followed up for six months. The same assessment was performed at 6 months post BR, and their satisfaction with BR was evaluated using the Alderman scale. Multivariate linear and logistic regressions were performed.

Results

Forty-seven percent of the patients (126/264) opted to undergo BR within six months after the initial visit. Multivariate logistic regression analysis revealed that self-esteem (P < 0.05), body image (P < 0.01), education level (P < 0.05), and their husband’s recommendation (P < 0.05) were highly related to the patients’ decision to undergo BR. In addition, multivariate linear regression analysis showed that patient satisfaction with BR was significantly associated with preoperative body image (P < 0.01), postoperative improvement in self-esteem (P < 0.01), improvement in body image (P < 0.01), reduction in depression (P < 0.05), pain (P < 0.05), and scarring (P < 0.01).

Conclusions

The psychosocial factors including self-esteem and body image are highly related to selecting the BR option and post-BR satisfaction in Chinese female breast cancer patients.     

具收获与脉冲的时滞捕食模型研究

研究了与生物资源管理相关的食饵具脉冲扰动与成年捕食者具连续收获的阶段结构时滞捕食-食饵模型.利用离散动力系统的频闪映射和脉冲时滞微分方程理论,得到了捕食者灭绝周期解的全局吸引和系统持久的充分条件,也证明了系统的所有解的一致完全有界.结论为现实的可再生生物资源管理提供了可靠的策略依据.     

Maternal Obesity in Early Pregnancy and Risk of Adverse Outcomes

Objectives

To assess the role of the health consequences of maternal overweight and obesity at the start of pregnancy on gestational pathologies, delivery and newborn characteristics.

Methods

A cohort of pregnant women (n = 6.558) having delivered at the Maternal & Child University Hospital of Gran Canaria (HUMIGC) in 2008 has been studied. Outcomes were compared using multivariate analyses controlling for confounding variables.

Results

Compared to normoweight, overweight and obese women have greater risks of gestational diabetes mellitus (RR = 2.13 (95% CI: 1.52–2.98) and (RR = 2.85 (95% CI: 2.01–4.04), gestational hypertension (RR = 2.01 (95% CI: 1.27–3.19) and (RR = 4.79 (95% CI: 3.13–7.32) and preeclampsia (RR = 3.16 (95% CI: 1.12–8.91) and (RR = 8.80 (95% CI: 3.46–22.40). Obese women have also more frequently oligodramnios (RR = 2.02 (95% CI: 1.25–3.27), polyhydramnios. (RR = 1.76 (95% CI: 1.03–2.99), tearing (RR = 1.24 (95% CI: 1.05–1.46) and a lower risk of induced deliveries (RR = 0.83 (95% CI: 0.72–0.95). Both groups have more frequently caesarean section (RR = 1.36 (95% CI: 1.14–1.63) and (RR = 1.84 (95% CI: 1.53–2.22) and manual placenta extraction (RR = 1.65 (95% CI: 1.28–2.11) and (RR = 1.77 (95% CI: 1.35–2.33). Newborns from overweight and obese women have higher weight (p<0.001) and a greater risk of being macrosomic (RR = 2.00 (95% CI: 1.56–2.56) and (RR = 2.74 (95% CI: 2.12–3.54). Finally, neonates from obese mother have a higher risk of being admitted to special care units (RR = 1.34 (95% CI: 1.01–1.77). Apgar 1 min was significantly higher in newborns from normoweight mothers: 8.65 (95% CI: 8.62–8.69) than from overweight: 8.56 (95% CI: 8.50–8.61) or obese mothers: 8.48 (95% CI: 8.41–8.54).

Conclusion

Obesity and overweight status at the beginning of pregnancy increase the adverse outcomes of the pregnancy. It is important to promote the normalization of bodyweight in those women who intend to get pregnant and to provide appropriate advice to the obese women of the risks of obesity at the start of the pregnancy.     

Temporal Discounting Is Associated with an Increased Risk of Mortality among Community-Based Older Persons without Dementia

Background

Temporal discounting is an important determinant of many health and financial outcomes, but we are not aware of studies that have examined the association of temporal discounting with mortality.

Methods

Participants were 406 older persons without dementia from the Rush Memory and Aging Project, a longitudinal cohort study of aging. Temporal discounting was measured using standard preference elicitation questions. Individual discount rates were estimated using a well-established hyperbolic function and used to predict the risk of mortality during up to 5 years of follow-up.

Results

The mean estimate of discounting was 0.45 (SD = 0.33, range: 0.08–0.90), with higher scores indicating a greater propensity to prefer smaller immediate rewards over larger but delayed ones. During up to 5 years of follow-up (mean = 3.6 years), 62 (15% of 406) persons died. In a proportional hazards model adjusted for age, sex, and education, temporal discounting was associated with an increased risk of mortality (HR = 1.103, 95% CI 1.024, 1.190, p = 0.010). Thus, a person with the highest discount rate (score = 0.90) was about twice more likely to die over the study period compared to a person with the lowest discount rate (score = 0.08). Further, the association of discounting with mortality persisted after adjustment for the level of global cognitive function, the burden of vascular risk factors and diseases, and an indicator of psychological well being (i.e., purpose in life).

Conclusion

Temporal discounting is associated with an increased risk of mortality in old age after accounting for global cognitive function and indicators of physical and mental health.     

Average Waiting Time of Clusterhead Controlled Token for Virtual Base Station On-Demand in MANETs

A wireless mobile Ad hoc network (MANET) is a collection of wireless mobile hosts forming nodes that are arbitrarily and randomly changing their locations and communicating without the aid of any centralized administration or standard support services. Ad hoc cluster-based routing protocols establish a dynamic wireless mobile infrastructure to mimic the operation of the fixed infrastructure in cellular networks. A clusterhead is elected from a set of nominees, based on an agreed upon rule, to act as a temporary base station within its zone or autonomous system. Mobile stations elected as clusterheads are used to track other mobile stations in the ad hoc network. In each cluster, we use the clusterhead controlled token to assign the channel among contending Mobile Terminals (MTs). A clusterhead controlled token supports multiple class of services and minimizes collisions. In this paper, we derive formulas to calculate the average waiting time for a packet, in order to get transmitted. In our study, we use two polling schemes, namely: Exhaustive polling and Partially Gated polling controlled token.Tarek Sheltami is currently an assistant professor at the Computer Engineering Department at King Fahd University of Petroleum and Minerals (KFUPM) Dhahran, Kingdom of Saudi Arabia. He joined the department on September, 2004. Before joining the KFUPM, Dr. Sheltami was a research associate professor at the School of Information Technology and Engineering (SITE), University of Ottawa, Ontario, Canada. He has two years of industrial experience at GamaEng Inc (2002–2004). He is the co-author of the Warning Energy Aware Clusterhead (WEAC) infrastructure protocol and the Virtual Base Station On-demand (VBS-O) routing protocol. Dr. Sheltami has been a member of a technical program and organizing committees of several international IEEE conferences. Dr. Sheltamis research interests are in the area of wireless communications, wireless ad hoc and sensors networks, mobile infrastructure protocols, network control/mobility management, UMTS, and performance evaluation of wireless communication networks.Hussein Mouftah joined the School of Information Technology and Engineering (SITE) of the University of Ottawa in September 2002 as a Canada Research Chair (Tier 1) Professor in Optical Networks. He has been with the Department of Electrical and Computer Engineering at Queens University (1979–2002), where he was prior to his departure a Full Professor and the Department Associate Head. He has three years of industrial experience mainly at Bell Northern Research of Ottawa, now Nortel Networks (1977–79). He has spent three sabbatical years also at Nortel Networks (1986–87, 1993–94, and 2000–01), always conducting research in the area of broadband packet switching networks, mobile wireless networks and quality of service over the optical Internet. He served as Editor-in-Chief of the IEEE Communications Magazine (1995–97) and IEEE Communications Society Director of Magazines (1998–99) and Chair of the Awards Committee (2002–2003). He is a Distinguished Speaker of the IEEE Communications Society since 2000. Dr. Mouftah is the author or coauthor of five books, 22 book chapters and more than 700 technical papers and 8 patents in this area. He is the recipient of the 1989 Engineering Medal for Research and Development of the Association of Professional Engineers of Ontario (PEO), and the Ontario Distinguished Researcher Award of the Ontario Innovation Trust. He is the joint holder of the Best Paper Award for a paper presented at SPECTS 2002, and the Outstanding Paper Award for papers presented at the IEEE HPSR 2002 and the IEEE ISMVLõ1985. Also he is the joint holder of a Honorable Mention for the Frederick W. Ellersick Price Paper Award for Best Paper in the IEEE Communications Magazine in 1993. He is the recipient of the IEEE Canada (Region 7) Outstanding Service Award (1995). Also he is the recipient of the 2004 IEEE Communications Society Edwin Howard Armstrong Achievement Award, and the 2004 George S. Glinski Award for Excellence in Research of the Faculty of Engineering, University of Ottawa. Dr. Mouftah is a Fellow of the IEEE (1990), the Canadian Academy of Engineering (2003) and the Engineering Institute of Canada (2005).