Discrete but variable structure of animal societies leads to the false perception of a social continuum

Animal societies are typically divided into those in which reproduction within a group is monopolized by a single female versus those in which it is shared among multiple females. It remains controversial, however, whether these two forms of social structure represent distinct evolutionary outcomes or endpoints along a continuum of reproductive options. To address this issue and to determine whether vertebrates and insects exhibit the same patterns of variation in social structure, we examined the demographic and reproductive structures of 293 species of wasps, ants, birds and mammals. Using phylogenetically informed comparative analyses, we found strong evidence indicating that not all reproductive arrangements within social groups are viable in nature and that in societies with multiple reproductives, selection favours instead taxon-specific patterns of decrease in the proportion of breeders as a function of group size. These outcomes suggest that the selective routes to sociality differ depending upon whether monopolization of reproduction by one individual is possible and that variation within and among taxonomic groups may lead to the false perception of a continuum of social structures. Thus, the occurrence of very large societies may require either complete reproductive monopolization (monogyny/singular breeding) or the maintenance of a taxon-specific range of values for the proportional decrease in the number of breeders within a group (polygyny/plural breeding), both of which may reduce reproductive conflict among females

Finite-Temperature Auxiliary-Field Quantum Monte Carlo for Bose-Fermi Mixtures

We present a quantum Monte Carlo (QMC) technique for calculating the exact finite-temperature properties of Bose-Fermi mixtures. The Bose-Fermi Auxiliary-Field Quantum Monte Carlo (BF-AFQMC) algorithm combines two methods, a finite-temperature AFQMC algorithm for bosons and a variant of the standard AFQMC algorithm for fermions, into one algorithm for mixtures. We demonstrate the accuracy of our method by comparing its results for the Bose-Hubbard and Bose-Fermi-Hubbard models against those produced using exact diagonalization for small systems. Comparisons are also made with mean-field theory and the worm algorithm for larger systems. As is the case with most fermion Hamiltonians, a sign or phase problem is present in BF-AFQMC. We discuss the nature of these problems in this framework and describe how they can be controlled with well-studied approximations to expand BF-AFQMC's reach. The new algorithm can serve as an essential tool for answering many unresolved questions about many-body physics in mixed Bose-Fermi systems.Comment: 19 pages, 6 figure

Tbr1 instructs laminar patterning of retinal ganglion cell dendrites.

Visual information is delivered to the brain by >40 types of retinal ganglion cells (RGCs). Diversity in this representation arises within the inner plexiform layer (IPL), where dendrites of each RGC type are restricted to specific sublaminae, limiting the interneuronal types that can innervate them. How such dendritic restriction arises is unclear. We show that the transcription factor Tbr1 is expressed by four mouse RGC types with dendrites in the outer IPL and is required for their laminar specification. Loss of Tbr1 results in elaboration of dendrites within the inner IPL, while misexpression in other cells retargets their neurites to the outer IPL. Two transmembrane molecules, Sorcs3 and Cdh8, act as effectors of the Tbr1-controlled lamination program. However, they are expressed in just one Tbr1+ RGC type, supporting a model in which a single transcription factor implements similar laminar choices in distinct cell types by recruiting partially non-overlapping effectors

Bolus clearance in esophagogastric junction outflow obstruction is associated with strength of peristalsis

BackgroundA manometric diagnosis of esophagogastric junction outflow obstruction (EGJOO) without a mechanical cause creates a therapeutic conundrum. The aim of this study was to assess esophageal bolus clearance in EGJOO and assess manometric factors associated with clearance in EGJOO.MethodsBolus clearance was assessed using line‐tracing method and contour method to determine Complete Bolus Transit (CBT) and Functional Clearance (FC), respectively, on combined High‐Resolution Impedance Manometry (HRIM). HRIM studies of EGJOO patients, as well as a sample of achalasia types I‐III and asymptomatic controls, were retrospectively analyzed. In EGJOO, associations between Integrated Relaxation Pressure (IRP) or Distal Contractile Integral (DCI) and clearance were assessed using receiver‐operating‐characteristic (ROC) curves.Key ResultsSeventy‐five EGJOO, 28 achalasia, and 11 normal subjects were included. Agreement between CBT and FC was good (Kappa=0.75). CBT across swallows in each group was as follows: type I achalasia: 14%, type II achalasia: 8%, type III achalasia: 61%, EGJOO: 86%, and normal: 98% (p values .023, .006, and 610 mmHg‐s‐cm (accuracy 87.7%, P=.004). Complete Bolus Transit( CBT) across individual swallows was 97.8% when DCI>884 mmHg‐s‐cm (accuracy 81.9%, P900 mmHg‐s‐cm.Esophagogastric junction outflow obstruction (EGJOO) is a manometric diagnosis with unclear clinical significance. We studied bolus clearance in EGJOO, including in relationship to Distal Contractile Integral (DCI) and Integrated Relaxation Pressure (IRP). We found that intact peristalsis defined as a DCI of greater than 900 mmHg‐s‐cm is associated with complete bolus transit.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138211/1/nmo13093_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138211/2/nmo13093.pd

Temporal Course of the Tourette Syndrome Clinical Triad

Background: Tourette syndrome (TS) is a disorder characterized by childhood onset of motor and phonic tics, often with improvement of tic symptoms by young adult years. The temporal course of tics and commonly comorbid behavioral symptoms is still not well characterized. Methods: In order to clarify the time course of tics and comorbid attention deficit hyperactivity disorder (ADHD) or obsessive compulsive disorder (OCD) in TS, we administered a brief survey regarding the course of symptoms at a single point in time to 53 TS patients aged 13–31 years. Results: Mean age (±SD) at symptom onset was 7.9 (±3.6) years for tics, 7.9 (±3.5) for ADHD, and 9.2 (±5.0) for OCD. Age at peak symptom severity was 12.3 (±4.6) years for tics, 10.8 (±3.8) for ADHD, and 12.6 (±5.5) for OCD. Tics, ADHD, and OCD were reported to be no longer present in 32.0%, 22.8%, and 21.0% of subjects, respectively. Decline in symptom severity began at age 14.7 (±3.7) years for tics, 13.9 (±2.9) for ADHD, and 15.1 (±5.0) for OCD. Remission of symptoms occurred at age 17.4 (±3.8) years for tics, 17.4 (±1.3) for ADHD, and 15.6 (±2.3) for OCD. Discussion: Our data confirm and expand previously reported TS spectrum symptom milestones and may guide design of future research aimed at improving the course of TS. Keywords: Tourette, obsessive compulsive disorder, attention deficit hyperactivity disorder, tic Citation: Shprecher DR, Rubenstein LA, Gannon K, et al. Temporal course of the Tourette syndrome clinical triad. Tremor Other Hyperkinet Mov. 2014; 4. doi: 10.7916/D8HD7SV

Coupled dynamics of voltage and calcium in paced cardiac cells

We investigate numerically and analytically the coupled dynamics of transmembrane voltage and intracellular calcium cycling in paced cardiac cells using a detailed physiological model and its reduction to a three-dimensional discrete map. The results provide a theoretical framework to interpret various experimentally observed modes of instability ranging from electromechanically concordant and discordant alternans to quasiperiodic oscillations of voltage and calcium

Are superflares on solar analogues caused by extra-solar planets?

Stellar flares with ${10^2-10^7}$ times more energy than the largest solar flare have been detected from 9 normal F and G main sequence stars (Schaefer, King & Deliyannis 1999). These superflares have durations of hours to days and are visible from at least x-ray to optical frequencies. The absence of world-spanning aurorae in historical records and of anomalous extinctions in the geological record indicate that our Sun likely does not suffer superflares. In seeking to explain this new phenomenon, we are struck by its similarity to large stellar flares on RS Canum Venaticorum binary systems, which are caused by magnetic reconnection events associated with the tangling of magnetic fields between the two stars. The superflare stars are certainly not of this class, although we propose a similar flare mechanism. That is, superflares are caused by magnetic reconnection between fields of the primary star and a close-in Jovian planet. Thus, by only invoking known planetary properties and reconnection scenarios, we can explain the energies, durations, and spectra of superflares, as well as explain why our Sun does not have such events.Comment: 13 pages, Accepted for publication in Ap

Indeterminacy of Spatiotemporal Cardiac Alternans

Cardiac alternans, a beat-to-beat alternation in action potential duration (at the cellular level) or in ECG morphology (at the whole heart level), is a marker of ventricular fibrillation, a fatal heart rhythm that kills hundreds of thousands of people in the US each year. Investigating cardiac alternans may lead to a better understanding of the mechanisms of cardiac arrhythmias and eventually better algorithms for the prediction and prevention of such dreadful diseases. In paced cardiac tissue, alternans develops under increasingly shorter pacing period. Existing experimental and theoretical studies adopt the assumption that alternans in homogeneous cardiac tissue is exclusively determined by the pacing period. In contrast, we find that, when calcium-driven alternans develops in cardiac fibers, it may take different spatiotemporal patterns depending on the pacing history. Because there coexist multiple alternans solutions for a given pacing period, the alternans pattern on a fiber becomes unpredictable. Using numerical simulation and theoretical analysis, we show that the coexistence of multiple alternans patterns is induced by the interaction between electrotonic coupling and an instability in calcium cycling.Comment: 20 pages, 10 figures, to be published in Phys. Rev.