A family of compact semitoric systems with two focus-focus singularities

About 6 years ago, semitoric systems were classified by Pelayo & Vu Ngoc by means of five invariants. Standard examples are the coupled spin oscillator on $\mathbb{S}^2 \times \mathbb{R}^2$ and coupled angular momenta on $\mathbb{S}^2 \times \mathbb{S}^2$, both having exactly one focus-focus singularity. But so far there were no explicit examples of systems with more than one focus-focus singularity which are semitoric in the sense of that classification. This paper introduces a 6-parameter family of integrable systems on $\mathbb{S}^2 \times \mathbb{S}^2$ and proves that, for certain ranges of the parameters, it is a compact semitoric system with precisely two focus-focus singularities. Since the twisting index (one of the semitoric invariants) is related to the relationship between different focus-focus points, this paper provides systems for the future study of the twisting index.Comment: Update to most recent version: some typos removed; minor inaccuracies corrected; better layou

The twisting index in semitoric systems

In 2009-2011 Pelayo and V\~{u} Ngoc classified semitoric integrable systems in terms of five invariants. Four of the invariants were already well-understood prior to the classification, but the fifth invariant, the so-called twisting index invariant, came as a surprise. Having a better understanding of the twisting index invariant of a semitoric system is a necessary step towards extending the symplectic classification result to more general situations, such as almost-toric systems, hypersemitoric systems, or higher dimensional systems which admit underlying complexity-one torus actions. The twisting index encodes how the structure in a neighborhood of a focus-focus fiber compares to the large-scale structure of the semitoric system. Pelayo and V\~{u} Ngoc originally defined the twisting index in terms of comparing certain momentum maps. The first half of the paper is devoted to giving an equivalent definition of the twisting index in terms of topological-geometric objects, such as homology cycles. The second half of the paper is concerned with computing the twisting index of a specific family of systems (the generalized coupled angular momenta) with two focus-focus singular points, which is the first time that the twisting index has been computed for a system with more than one focus-focus point. Along the way, we also compute the terms of the Taylor series invariant up to second order, completing the computation of all five semitoric invariants for this system. Thus there is now a fully classified third family of semitoric systems after the completion of the classification of spin oscillators and coupled angular momenta (Alonso $\&$ Hohloch $\&$ Dullin in 2019 and 2020).Comment: 46 page, 16 figure

A Multiplex GPCR-Mediated Peptide Tagging System for a Growing Yeast Synthetic Biology Toolbox

Straightforward methods for specifically detecting and quantifying proteins are essential for both basic and applied research and notably in synthetic biology. Previously we demonstrated that the yeast mating pathway could be hijacked to detect species-specific fungal peptide pheromones using their corresponding mating GPCRs. Here we asked if our yeast biosensor could detect proteins in addition to peptides – a question not previously resolved in the literature. As such, we repurposed the Saccharomyces cerevisiae fungal mating pheromone α-factor as a peptide tag and fused it terminally and internally to the protein Smt3. Our biosensor was able to detect the tagged protein in the nanomolar range using fluorescence as a read-out. We extended the assay to four additional orthogonal peptide pheromone tags, demonstrating a cheap, non-labor-intensive, and high-throughput assay compatible with multiplexing for protein detection. With its ability to detect proteins our living yeast biosensor could be useful for the optimization of protein producing cell-factories, for building logic gates and myriad other applications in synthetic biology.</p

Poor neuro-motor tuning of the human larynx:A comparison of sung and whistled pitch imitation

Vocal imitation is a hallmark of human communication that underlies the capacity to learn to speak and sing. Even so, poor vocal imitation abilities are surprisingly common in the general population and even expert vocalists cannot match the precision of a musical instrument. Although humans have evolved a greater degree of control over the laryngeal muscles that govern voice production, this ability may be underdeveloped compared with control over the articulatory muscles, such as the tongue and lips, volitional control of which emerged earlier in primate evolution. Human participants imitated simple melodies by either singing (i.e. producing pitch with the larynx) or whistling (i.e. producing pitch with the lips and tongue). Sung notes were systematically biased towards each individual’s habitual pitch, which we hypothesize may act to conserve muscular effort. Furthermore, while participants who sung more precisely also whistled more precisely, sung imitations were less precise than whistled imitations. The laryngeal muscles that control voice production are under less precise control than the oral muscles that are involved in whistling. This imprecision may be due to the relatively recent evolution of volitional laryngeal-motor control in humans, which may be tuned just well enough for the coarse modulation of vocal-pitch in speech

Pseudoperiodic Words and a Question of Shevelev

We generalize the familiar notion of periodicity in sequences to a new kind of pseudoperiodicity, and we prove some basic results about it. We revisit the results of a 2012 paper of Shevelev and reprove his results in a simpler and more unified manner, and provide a complete answer to one of his previously unresolved questions. We consider finding words with specific pseudoperiod and having the smallest possible critical exponent. Finally, we consider the problem of determining whether a finite word is pseudoperiodic of a given size, and show that it is NP-complete

Delay to Surgical Treatment in Geriatric Hip Fracture Patients

Background: Hip fractures in the geriatric population are frequently encountered. There is increasing focus on minimizing the delay to surgery in these patients. This study was designed to evaluate factors responsible for a delay to surgery in a geriatric hip fracture population and how time to surgery affects mortality. Methods: A retrospective cohort of patients sustaining low energy geriatric hip fractures in either an American College of Surgeons (ACS) verified Level 1 trauma center or a local university affiliated community teaching hospital were reviewed. The following variables were evaluated as independent risk factors for delay to surgery: demographic data, surgical details, use of cardiology resources, treatment center, and comorbidities. As a secondary objective, the effect of time to surgery on 1 year mortality was analyzed. Results: 1157 patients met inclusion criteria. The following factors increased the risk of delay to surgery greater than 48 hours: male sex, treatment in a community hospital (versus trauma center), older age, multiple comorbidities (eg, cardiovascular-related conditions or other fractures), cardiology consultation, and an American Society of Anesthesiologists physical status score of 3 or 4. Cardiology consultation was the strongest independent predictor of risk for delay to surgery of >48 hours (odds ratio, 6.68; 95% confidence interval, 4.40 to 10.14; P Conclusion: The presence of cardiovascular comorbidities and cardiology consultations can delay surgical treatments for hip fractures in patients greater than 65 years old, but the delay did not influence 1-year all-cause mortality. Level of Evidence: Level IV.</p

Positive activities as protective factors against mental health conditions.

Applying Nolen-Hoeksema and Watkins’s (2011) transdiagnostic risk factor heuristic to our work on positive activities (i.e., practices that characterize naturally happy people, like expressing gratitude and practicing generosity), we propose that such activities may serve as protective factors that mitigate proximal risk factors both directly and by intervening with the mechanisms that give rise to them. First, we discuss theoretical and empirical support for the importance of well-being and the mechanisms that explain how positive activities promote well-being (by boosting positive emotions, positive thoughts, positive behaviors, and need satisfaction; Lyubomirsky &amp; Layous, 2013). Second, we outline examples of how positive activities can mitigate two particular proximal risk factors (rumination and loneliness) and counteract environmental triggers (i.e., moderators) that might amplify them (e.g., through adaptive coping). Third, we argue that positive activities can be taught to youth to instill positive patterns of emotions, thoughts, and behaviors that may serve as protective factors over the course of their lifetimes. Lastly, we propose that certain positive activities might be particularly well-suited to certain individuals and to specific risk factors

Designer Reagents for Mass Spectrometry-Based Proteomics: Clickable Cross-Linkers for Elucidation of Protein Structures and Interactions

We present novel homobifunctional amine-reactive clickable cross-linkers (CXLs) for investigation of three-dimensional protein structures and protein–protein interactions (PPIs). CXLs afford consolidated advantages not previously available in a simple cross-linker, including (1) their small size and cationic nature at physiological pH, resulting in good water solubility and cell-permeability, (2) an alkyne group for bio-orthogonal conjugation to affinity tags via the click reaction for enrichment of cross-linked peptides, (3) a nucleophilic displacement reaction involving the 1,2,3-triazole ring formed in the click reaction, yielding a lock-mass reporter ion for only clicked peptides, and (4) higher charge states of cross-linked peptides in the gas-phase for augmented electron transfer dissociation (ETD) yields. Ubiquitin, a lysine-abundant protein, is used as a model system to demonstrate structural studies using CXLs. To validate the sensitivity of our approach, biotin-azide labeling and subsequent enrichment of cross-linked peptides are performed for cross-linked ubiquitin digests mixed with yeast cell lysates. Cross-linked peptides are detected and identified by collision induced dissociation (CID) and ETD with linear quadrupole ion trap (LTQ)-Fourier transform ion cyclotron resonance (FTICR) and LTQ-Orbitrap mass spectrometers. The application of CXLs to more complex systems (e.g., in vivo cross-linking) is illustrated by Western blot detection of Cul1 complexes including known binders, Cand1 and Skp2, in HEK 293 cells, confirming good water solubility and cell-permeability

Chlamydophila pneumoniae derived from inclusions late in the infectious cycle induce aponecrosis in human aortic endothelial cells

BACKGROUND: Atherosclerosis is still the leading cause of death in the western world. Besides known risk factors studies demonstrating Chlamydophila pneumoniae (C. pneumoniae) to be implicated in the progression of the disease, little is known about C. pneumoniae infection dynamics. We investigated whether C. pneumoniae induce cell death of human aortic endothelial cells, a cell type involved in the initiation of atherosclerosis, and whether chlamydial spots derive from inclusions. RESULTS: Lactate dehydrogenase release revealed host cell death to be dependent on the amounts of Chlamydia used for infection. The morphology of lysed human aortic endothelial cells showed DNA strand breaks simultaneously with cell membrane damage exclusively in cells carrying Chlamydia as spots. Further ultrastructural analysis revealed additional organelle dilation, leading to the definition as aponecrotic cell death of endothelial cells. Exclusive staining of the metabolic active pathogens by chlamydial heat shock protein 60 labelling and ceramide incorporation demonstrated that the bacteria responsible for the induction of aponecrosis had resided in former inclusions. Furthermore, a strong pro-inflammatory molecule, high mobility group box protein 1, was shown to be released from aponecrotic host cells. CONCLUSION: From the data it can be concluded that aponecrosis inducing C. pneumoniae stem from inclusions, since metabolically active bacterial spots are strongly associated with aponecrosis late in the infectious cycle in vascular endothelial cells and metabolic activity was exclusively located inside of inclusions in intact cells. Vice versa initial spot-like infection with metabolically inert bacteria does not have an effect on cell death induction. Hence, C. pneumoniae infection can contribute to atherosclerosis by initial endothelial damage

Clustering by well-being in workplace social networks: Homophily and social contagion.

Social interaction among employees is crucial at both an organizational and individual level. Demonstrating the value of recent methodological advances, 2 studies conducted in 2 workplaces and 2 countries sought to answer the following questions: (a) Do coworkers interact more with coworkers who have similar well-being? and, if yes, (b) what are the processes by which such affiliation occurs? Affiliation was assessed via 2 methodologies: a commonly used self-report measure (i.e., mutual nominations by coworkers) complemented by a behavioral measure (i.e., sociometric badges that track physical proximity and social interaction). We found that individuals who share similar levels of well-being (e.g., positive affect, life satisfaction, need satisfaction, and job satisfaction) were more likely to socialize with one another. Furthermore, time-lagged analyses suggested that clustering in need satisfaction arises from mutual attraction (homophily), whereas clustering in job satisfaction and organizational prosocial behavior results from emotional contagion. These results suggest ways in which organizations can physically and socially improve their workplace. (PsycINFO Database Recor