Dimer percolation and jamming on simple cubic lattice

We consider site percolation of dimers (``neadles'') on simple cubic lattice. The percolation threshold is estimated as $p_c^\text{perc} \approx 0.2555 \pm 0.0001$. The jamming threshold is estimated as $p_c^\text{jamm} = 0.799 \pm 0.002$.Comment: 3 pages, 4 figures, submitted to EPJ

Today’s Dissection in English Lab: Analytical Discoveries Through Classical Rhetoric

This article describes a single class session in Fall Semester 2020 with my undergraduate freshmen, featuring a “lab” discussion of a poem by Sun Yung Shin. The “dissection” of her poem proceeds by means of an application of classical rhetorical tools -- particularly the appeals to logos, ethos, and pathos -- the “lenses” by means of which a process of critical analysis takes place. The intention of my article is to demonstrate how productively students can apply such rhetorical tools when they have been carefully trained in their use for several weeks in a semester. To shift the metaphor slightly, the dissection becomes an exercise in reverse engineering, one that produces original insights, or “inventions” that can lead directly to improvements in student writing

Unravelling the hybrid vigor in domestic equids: the effect of hybridization on bone shape variation and covariation

Hybridization has been widely practiced in plant and animal breeding as a means to enhance the quality and fitness of the organisms. In domestic equids, this hybrid vigor takes the form of improved physical and physiological characteristics, notably for strength or endurance. Because the offspring of horse and donkey is generally sterile, this widely recognized vigor is expressed in the first generation (F1). However, in the absence of recombination between the two parental genomes, F1 hybrids can be expected to be phenotypically intermediate between their parents which could potentially restrict the possibilities of an increase in overall fitness. In this study, we examine the morphology of the main limb bones of domestic horses, donkeys and their hybrids to investigate the phenotypic impact of hybridization on the locomotor system. We explore bone shape variation and covariation to gain insights into the morphological and functional expressions of the hybrid vigor commonly described in domestic equids

2-Dust : a Dust Radiative Transfer Code for an Axisymmetric System

We have developed a general purpose dust radiative transfer code for an axisymmetric system, 2-Dust, motivated by the recent increasing availability of high-resolution images of circumstellar dust shells at various wavelengths. This code solves the equation of radiative transfer following the principle of long characteristic in a 2-D polar grid while considering a 3-D radiation field at each grid point. A solution is sought through an iterative scheme in which self-consistency of the solution is achieved by requiring a global luminosity constancy throughout the shell. The dust opacities are calculated through Mie theory from the given size distribution and optical properties of the dust grains. The main focus of the code is to obtain insights on (1) the global energetics of dust grains in the shell (2) the 2-D projected morphologies that are strongly dependent on the mixed effects of the axisymmetric dust distribution and inclination angle of the shell. Here, test models are presented with discussion of the results. The code can be supplied with a user-defined density distribution function, and thus, is applicable to a variety of dusty astronomical objects possessing the axisymmetric geometry.Comment: To be published in ApJ, April 2003 issue; 13 pages, 4 tables, 17 figures, 5-page appendix (no figures for the main text included in this preprint). For the complete preprint and code distribution, contact the author

Replicators in Fine-grained Environment: Adaptation and Polymorphism

Selection in a time-periodic environment is modeled via the two-player replicator dynamics. For sufficiently fast environmental changes, this is reduced to a multi-player replicator dynamics in a constant environment. The two-player terms correspond to the time-averaged payoffs, while the three and four-player terms arise from the adaptation of the morphs to their varying environment. Such multi-player (adaptive) terms can induce a stable polymorphism. The establishment of the polymorphism in partnership games [genetic selection] is accompanied by decreasing mean fitness of the population.Comment: 4 pages, 2 figure

The neural substrate of orientation short-term memory and resistance to distractor items

Abstract We used Positron Emission Tomography to map the neural substrate of human short-term memory for orientation, de®ned as retaining a single orientation in memory over a long delay, by comparing a successive discrimination task with a 6-s delay to the same task with a brief 0.3 s delay and to an identi®cation control task. Short-term memory engaged the superior parietal lobe bilaterally, the middle occipital gyrus bilaterally and the left dorsolateral prefrontal cortex. In addition, we studied the resistance to a distractor item by comparing the successive discrimination task with long delay, with and without an intervening distractor stimulus. This manipulative process engaged left ventral premotor cortex and left dorsolateral prefrontal cortex. The activation of left dorsolateral prefrontal cortex is interpreted as re¯ecting co-ordination between task components. These results, combined with those of two previous studies using an identical reduction strategy, underscore the functional heterogeneity in the prefrontal cortex during short-term and working memory

Karyotypical characteristics of two allopatric African populations of anhydrobiotic Polypedilum Kieffer, 1912 (Diptera, Chironomidae) originating from Nigeria and Malawi

The African chironomid Polypedilum vanderplanki Hinton, 1951 is the only chironomid able to withstand almost complete desiccation in an ametabolic state known as anhydrobiosis. The karyotypes of two allopatric populations of this anhydrobiotic chironomid, one from Nigeria and another from Malawi, were described according to the polytene giant chromosomes. The karyotype from the Nigerian population was presented as the reference chromosome map for P. vanderplanki. Both populations, Nigerian and Malawian, showed the same number of chromosomes (2n=8), but important differences were found in the band sequences of polytene chromosomes, and in the number and the arrangement of active regions between the two populations. Such important differences raise the possibility that the Malawian population could constitute a distinct new species of anhydrobiotic chironomid

Oscillating Positive Airway Pressure Versus CPAP for the Treatment of Obstructive Sleep Apnea

Although continuous positive airway pressure (CPAP) is the most effective therapy for obstructive sleep apnea (OSA), it is not always well tolerated by the patients. Previous physiological studies showed that pressure oscillations applied to the pharynx could activate upper airway muscles, but it is not clear whether these pressure oscillations could be tolerated during sleep in OSA patients. The aim of this study was to assess the tolerance of oscillating positive airway pressure (O-PAP) (a CPAP device delivering high-frequency pressure oscillations to the upper airway) compared to CPAP. Fourteen OSA patients currently on CPAP [age 59.9 ± 10.1 years old, BMI 34.8 ± 7.2 kg/m(2), initial apnea-hypopnea index (AHI): 58.7 ± 25.2 events/h] used O-PAP or CPAP on two consecutive nights under polysomnography, in a single-blind randomized crossover design to assess sleep quality. A subtherapeutic pressure (70% of the optimal titrated pressure) was applied in both conditions and the residual AHI with each technique was also compared. There was no difference in measured or perceived sleep quality between the two treatment modalities (sleep efficiency 90.0% versus 88.1%, p = 0.54). Despite the small sample, we also found a trend toward a decrease in residual respiratory events with O-PAP compared to CPAP (median AHI 14.3 versus 20.5/h, p = 0.194). The good tolerance of O-PAP and the positive trend toward a reduction in residual AHI should stimulate further research on the effects of O-PAP in OSA patients

Effects of antiplatelet therapy on menstrual blood loss in reproductive-aged women:a systematic review

Background: The effects of antiplatelet therapy on menstrual bleeding have not been well characterized. Objectives: To systematically review the effects of antiplatelet therapy on menstrual bleeding. Methods: A literature search was performed for studies of reproductive-aged women who received antiplatelet therapy. Characteristics of menstrual bleeding both before and after initiation of antiplatelet therapy and from comparison groups were collected. Two reviewers independently assessed the risk of bias in individual studies. Results: Thirteen studies with a total of 611 women who received antiplatelet therapy were included. Types of antiplatelet drugs used were aspirin (n = 8), aspirin and/or clopidogrel (n = 2), prasugrel (n = 1), and not specified (n = 2). Risk of bias was assessed at moderate (n = 1), serious (n = 8), critical (n = 2), and no information (n = 2). Three studies reported changes in menstrual blood loss volume. One of these showed no increase during antiplatelet therapy; the other 2 studies suggested that aspirin may increase menstrual blood loss volume. In 3 studies that assessed the duration of menstrual bleeding, up to 13% of women reported an increased duration of menstruation. In 5 studies that reported the intensity of menstrual flow, 13% to 38% of women experienced an increase in the intensity of flow. Five studies reported the prevalence of heavy menstrual bleeding in women who received antiplatelet therapy, with estimates ranging from 7% to 38%. Conclusion: There is lack of high-quality data on the effects of antiplatelet therapy on menstrual bleeding. Aspirin may increase menstrual blood loss, at least in a minority of women, whereas the effects of P2Y12 inhibitors are unknown.</p

Nationwide confidential enquiries into maternal deaths because of obstetric hemorrhage in the Netherlands between 2006 and 2019

Introduction: Obstetric hemorrhage-related deaths are rare in high income countries. Yet, with increasing incidences of obstetric hemorrhage in these countries, it is of utmost importance to learn lessons from each obstetric hemorrhage-related death to improve maternity care. Our objective was to calculate the obstetric hemorrhage-related maternal mortality ratio (MMR), assess causes of obstetric hemorrhage-related deaths, and identify lessons learned. Material and methods: Nationwide mixed-methods prospective case-series with confidential enquiries into maternal deaths due to obstetric hemorrhage in the Netherlands from January 1, 2006 to December 31, 2019. Results: The obstetric hemorrhage-related MMR in the Netherlands in 2006–2019 was 0.7 per 100 000 livebirths and was not statistically significantly different compared with the previous MMR of 1.0 per 100 000 livebirths in 1993–2005 (odds ratio 0.70, 95% confidence interval 0.38–1.30). Leading underlying cause of hemorrhage was retained placenta. Early recognition of persistent bleeding, prompt involvement of a senior clinician and timely management tailored to the cause of hemorrhage with attention to coagulopathy were prominent lessons learned. Also, timely recourse to surgical interventions, including hysterectomy, in case other management options fail to stop bleeding came up as an important lesson in several obstetric hemorrhage-related deaths. Conclusions: The obstetric hemorrhage-related MMR in the Netherlands in 2006–2019 has not substantially changed compared to the MMR of the previous enquiry in 1993–2005. Although obstetric hemorrhage is commonly encountered by maternity care professionals, it is important to remain vigilant for possible adverse maternal outcomes and act upon an ongoing bleeding following birth in a more timely and adequate manner. Our confidential enquiries still led to important lessons learned with clinical advice to professionals as how to improve maternity care and avoid maternal deaths. Drawing lessons from maternal deaths should remain a qualitative and moral imperative