2-Segal sets and the Waldhausen construction

It is known by results of Dyckerhoff–Kapranov and of Gálvez-Carrillo–Kock–Tonks that the output of the Waldhausen S • -construction has a unital 2-Segal structure. Here, we prove that a certain S • -functor defines an equivalence between the category of augmented stable double categories and the category of unital 2-Segal sets. The inverse equivalence is described explicitly by a path construction. We illustrate the equivalence for the known examples of partial monoids, cobordism categories with genus constraints and graph coalgebras

Acetylcholine-induced Calcium Signaling and Contraction of Airway Smooth Muscle Cells in Lung Slices

The Ca2+ signaling and contractility of airway smooth muscle cells (SMCs) were investigated with confocal microscopy in murine lung slices (∼75-μm thick) that maintained the in situ organization of the airways and the contractility of the SMCs for at least 5 d. 10–500 nM acetylcholine (ACH) induced a contraction of the airway lumen and a transient increase in [Ca2+]i in individual SMCs that subsequently declined to initiate multiple intracellular Ca2+ oscillations. These Ca2+ oscillations spread as Ca2+ waves through the SMCs at ∼48 μm/s. The magnitude of the airway contraction, the initial Ca2+ transient, and the frequency of the subsequent Ca2+ oscillations were all concentration-dependent. In a Ca2+-free solution, ACH induced a similar Ca2+ response, except that the Ca2+ oscillations ceased after 1–1.5 min. Incubation with thapsigargin, xestospongin, or ryanodine inhibited the ACH-induced Ca2+ signaling. A comparison of airway contraction with the ACH-induced Ca2+ response of the SMCs revealed that the onset of airway contraction correlated with the initial Ca2+ transient, and that sustained airway contraction correlated with the occurrence of the Ca2+ oscillations. Buffering intracellular Ca2+ with BAPTA prohibited Ca2+ signaling and airway contraction, indicating a Ca2+-dependent pathway. Cessation of the Ca2+ oscillations, induced by ACH-esterase, halothane, or the absence of extracellular Ca2+ resulted in a relaxation of the airway. The concentration dependence of the airway contraction matched the concentration dependence of the increased frequency of the Ca2+ oscillations. These results indicate that Ca2+ oscillations, induced by ACH in murine bronchial SMCs, are generated by Ca2+ release from the SR involving IP3- and ryanodine receptors, and are required to maintain airway contraction

Genetic diversity, infection prevalence, and possible transmission routes of Bartonella spp. in vampire bats

Bartonella spp. are globally distributed bacteria that cause endocarditis in humans and domestic animals. Recent work has suggested bats as zoonotic reservoirs of some human Bartonella infections; however, the ecological and spatiotemporal patterns of infection in bats remain largely unknown. Here we studied the genetic diversity, prevalence of infection across seasons and years, individual risk factors, and possible transmission routes of Bartonella in populations of common vampire bats (Desmodus rotundus) in Peru and Belize, for which high infection prevalence has previously been reported. Phylogenetic analysis of the gltA gene for a subset of PCR-positive blood samples revealed sequences that were related to Bartonella described from vampire bats from Mexico, other Neotropical bat species, and streblid bat flies. Sequences associated with vampire bats clustered significantly by country but commonly spanned Central and South America, implying limited spatial structure. Stable and nonzero Bartonella prevalence between years supported endemic transmission in all sites. The odds of Bartonella infection for individual bats was unrelated to the intensity of bat flies ectoparasitism, but nearly all infected bats were infested, which precluded conclusive assessment of support for vector-borne transmission. While metagenomic sequencing found no strong evidence of Bartonella DNA in pooled bat saliva and fecal samples, we detected PCR positivity in individual saliva and feces, suggesting the potential for bacterial transmission through both direct contact (i.e., biting) and environmental (i.e., fecal) exposures. Further investigating the relative contributions of direct contact, environmental, and vector-borne transmission for bat Bartonella is an important next step to predict infection dynamics within bats and the risks of human and livestock exposures

Analysis of shear test method for composite laminates

An elastic plane stress finite element analysis of the stress distributions in four flat test specimens for in-plane shear response of composite materials subjected to mechanical or thermal loads is presented. The shear test specimens investigated include: slotted coupon, cross beam, losipescu, and rail shear. Results are presented in the form of normalized shear contour plots for all three in-plane stess components. It is shown that the cross beam, losipescu, and rail shear specimens have stress distributions which are more than adequate for determining linear shear behavior of composite materials. Laminate properties, core effects, and fixture configurations are among the factors which were found to influence the stress distributions

Flow Equation for Supersymmetric Quantum Mechanics

We study supersymmetric quantum mechanics with the functional RG formulated in terms of an exact and manifestly off-shell supersymmetric flow equation for the effective action. We solve the flow equation nonperturbatively in a systematic super-covariant derivative expansion and concentrate on systems with unbroken supersymmetry. Already at next-to-leading order, the energy of the first excited state for convex potentials is accurately determined within a 1% error for a wide range of couplings including deeply nonperturbative regimes.Comment: 24 pages, 8 figures, references added, typos correcte

Reduced expression of Bax in small cell lung cancer cells is not sufficient to induce cisplatin-resistance

Resistance to cisplatin in the course of chemotherapy contributes to the poor prognosis of small cell lung cancer (SCLC). B cell lymphoma-2 is the founding member of a large family of proteins that either promote or inhibit apoptosis. We aimed at investigating if the pro-apoptotic members Bad, Bax, Bim and Bid are involved in cisplatin-resistance

Diabetes mellitus and sudden cardiac death: What are the data?

Diabetes mellitus has long been linked to an increased risk of sudden cardiac death. However, the magnitude of this association, and the mechanism accounting for this phenomenon, have not been precisely defined. In this review, we evaluate the epidemiological data pertaining to the association between diabetes mellitus and sudden cardiac death and discuss various proposed mechanisms that may account for this relationship. Potential factors contributing to the increased risk of sudden cardiac death observed in patients with diabetes mellitus include silent myocardial ischemia, autonomic nervous system dysfunction, abnormal cardiac repolarization, hypoglycemia, a hypercoaguable state secondary to diabetes mellitus, diabetic cardiomyopathy, and impaired respiratory response to hypoxia and hypercapnea. We conclude that diabetes mellitus does appear to be associated with an increased risk of sudden cardiac death. Although this increased risk is relatively modest, given the large number of diabetic patients worldwide, the absolute number of sudden cardiac deaths attributable to diabetes mellitus remains significant. Little evidence exists to support any specific mechanism(s) accounting for this association. Further investigation into the pathophysiology of sudden cardiac death in diabetes mellitus may yield improved risk stratification tools as well as identify novel therapeutic targets. (Cardiol J 2010; 17, 2: 117-129

Why Use Multiple Choice Questions with Excess Information?

The examinations administered by accounting instructors, professional certification examiners, textbook writers, and preparatory accounting software all routinely include multiple-choice (MC) questions with excess (yet related) information. Despite their widespread use, little is known about how MC questions with excess information (hereafter MCE questions) affect student test performance. Based on an empirical analysis of the tests of 374 students in two introductory accounting classes at a single university, we found that average performance was lower on MCE questions than non-MCE questions, but was sensitive to the overall difficulty of the tested concept. We also found no significant difference in the power of the two question types to discriminate—both types appeared equally competent in differentiating between low- and high-performing students. Although accounting professors may wish to use MC questions with excess information for a number of other reasons, we found that MCE questions, as used in the present setting, do not appear to better discriminate student understanding relative to non-MCE questions

Group actions on Segal operads

We give a Quillen equivalence between model structures for simplicial operads, described via the theory of operads, and Segal operads, thought of as certain reduced dendroidal spaces. We then extend this result to give an Quillen equivalence between the model structures for simplicial operads equipped with a group action and the corresponding Segal operads.Comment: Revised version. Accepted to Isr J Mat