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Approaches to understanding infectious disease dynamics often emphasise studies of multiple hosts or pathogens, but for many diseases, population structure may play a more important role. Changes in population structure may stem from heterogeneity of infection risk in the host population, pathogen polymorphism, spatial structure, or host population size structure. We review previous work demonstrating effects of population structure on baculoviruses of two insects in North America, focusing on heterogeneity in infection risk, which has consequences for both single epizootics and long-term host–pathogen population cycles. Baculoviruses’ simple biology and their insect hosts’ small size means that insect–baculovirus interactions provide experimentally tractable systems for testing models. Our research has combined mechanistic models with data using a combination of statistical model selection, Bayesian statistics, and time-series probes, allowing us to show how host variation affects disease dynamics and pathogen coexistence, and how variation is affected by host-plant resource quality, climate change, and host population size structure. We also discuss how Bayesian mixture models can make it possible to combine multiple sources of data collected across a range of scales.
OBJECTIVES/SPECIFIC AIMS: Neurologic disorders are among the most significant health challenges facing society today. Although different neurologic disorders are often thought to be distinct from one another, evidence suggests similar processes may contribute to pathology in different diseases. Previous studies suggest that common disease mechanisms contribute to the development of epilepsy and tauopathy. The purpose of this study is to better characterize this relationship and explore potential therapeutic avenues to slow disease progress. METHODS/STUDY POPULATION: This study uses the pilocarpine-induced status epilepticus model of temporal lobe epilepsy to explore the effect of severe seizures on tau pathology. Brains were collected from mice at 6 or 24 hours after induced status epilepticus. Homogenates were analyzed via Western blot to look for changes in tau phosphorylation or activity of two major regulators of tau phosphorylation, GSK3β and PP2A. These data show that changes in tau phosphorylation dynamics occur at a much earlier time point after status epilepticus than has previously been described. RESULTS/ANTICIPATED RESULTS: GSK3β activity increased within 6 hours and remained elevated by 24 hours. PP2A activity initially decreased but returned to normal by 24 hours. These data show that changes in tau phosphorylation dynamics occur at a much earlier time point after status epilepticus than has previously been described. DISCUSSION/SIGNIFICANCE OF IMPACT: The current project supports previous observations that seizures promote tau phosphorylation in vivo, but suggests that changes begin much earlier than previously thought. Further work is needed to understand how post-seizure changes in tau phosphorylation develop over longer periods of time. Additionally, future work will characterize the effect of tauopathy on electrical activity in vivo and in vivo.
Interpreting changes in ecosystem structure from the fossil record can be challenging. In a prominent example, the traditional view that brachiopods were ecologically dominant over bivalves in the Paleozoic has been disputed on both taphonomic and metabolic grounds. Aragonitic bivalves may be underrepresented in many fossil assemblages due to preferential dissolution. Abundance counts may further understate the ecological importance of bivalves, which tend to have more biomass and higher metabolic rates than brachiopods. We evaluate the relative importance of the two clades in exceptionally preserved, bulk-sampled fossil assemblages from the Pennsylvanian Breathitt Formation of Kentucky, where aragonitic bivalves are preserved as shells, not molds. At the regional scale, brachiopods were twice as abundant as bivalves and were collectively equivalent in biomass and energy use. Analyses of samples from the Paleobiology Database that contain abundance counts are consistent with these results and show no clear trend in the relative ecological importance of bivalves during the middle and late Paleozoic. Bivalves were probably more important in Paleozoic ecosystems than is apparent in many fossil assemblages, but they were not clearly dominant over brachiopods until after the Permian–Triassic extinction, which caused the shelly benthos to shift from bivalve and brachiopod dominated to merely bivalve dominated.
Collisionless shocks have been the subject on many studies in recent years, due to their ability to accelerate particles. In order to do so, a shock must fulfill three criteria. First, it must be strong enough to accelerate particles efficiently. Second, both the upstream and the downstream must be collisionless. Third, the shock front must be surrounded by electromagnetic turbulence capable of scattering particles back and forth. We here consider the encounter of two identical plasma shells with initial density, temperature, and velocity n0, T0, v0, respectively. We translate the three criteria to the corresponding requirements on these parameters. A non-trivial map of the allowed region for particle acceleration emerges in the (n0, T0, v0) phase space, especially at low velocities or high densities. We first assess the case of pair plasma shells, before we turn to electrons/protons.
Collisionless shocks follow the Rankine–Hugoniot jump conditions to a good approximation. However, for a shock propagating parallel to a magnetic field, magnetohydrodynamics states that the shock properties are independent of the field strength, whereas recent particle-in-cell simulations reveal a significant departure from magnetohydrodynamics behaviour for such shocks in the collisionless regime. This departure is found to be caused by a field-driven anisotropy in the downstream pressure, but the functional dependence of this anisotropy on the field strength is yet to be determined. Here, we present a non-relativistic model of the plasma evolution through the shock front, allowing for a derivation of the downstream anisotropy in terms of the field strength. Our scenario assumes double adiabatic evolution of a pair plasma through the shock front. As a result, the perpendicular temperature is conserved. If the resulting downstream is firehose stable, then the plasma remains in this state. If unstable, it migrates towards the firehose stability threshold. In both cases, the conservation equations, together with the relevant hypothesis made on the temperature, allows a full determination of the downstream anisotropy in terms of the field strength.
Patient expectancy is an important source of placebo effects in antidepressant clinical trials, but all prior studies measured expectancy prior to the initiation of medication treatment. Little is known about how expectancy changes during the course of treatment and how such changes influence clinical outcome. Consequently, we undertook the first analysis to date of in-treatment expectancy during antidepressant treatment to identify its clinical and demographic correlates, typical trajectories, and associations with treatment outcome.
Data were combined from two randomized controlled trials of antidepressant medication for major depressive disorder in which baseline and in-treatment expectancy assessments were available. Machine learning methods were used to identify pre-treatment clinical and demographic predictors of expectancy. Multilevel models were implemented to test the effects of expectancy on subsequent treatment outcome, disentangling within- and between-patient effects.
Random forest analyses demonstrated that whereas more severe depressive symptoms predicted lower pre-treatment expectancy, in-treatment expectancy was unrelated to symptom severity. At each measurement point, increased in-treatment patient expectancy significantly predicted decreased depressive symptoms at the following measurement (B = −0.45, t = −3.04, p = 0.003). The greater the gap between expected treatment outcomes and actual depressive severity, the greater the subsequent symptom reductions were (B = 0.49, t = 2.33, p = 0.02).
Greater in-treatment patient expectancy is associated with greater subsequent depressive symptom reduction. These findings suggest that clinicians may benefit from monitoring and optimizing patient expectancy during antidepressant treatment. Expectancy may represent another treatment parameter, similar to medication compliance and side effects, to be regularly monitored during antidepressant clinical management.
Let us Draw on the past as we look toward the future. Specifically, let us begin with the Propositiones ad acuendos juvenes, or “Problems to Sharpen the Young,” by Alcuin of York. Written sometime in the later eighth century, this text offers a number of logical and mathematical problems meant, as the title suggests, to refine one’s intellect. Some of the problems are fairly straightforward, as in the case of a question about how many sheep might fit in a field measuring 200 × 100 feet, with each sheep being allocated a space of 5 × 4 feet. Others, like de porcis, are somewhat trickier. This latter example is an impossible puzzle that asks how one might slaughter 300 pigs in three days by only slaughtering an odd number on each of the days.
. The nature and evolution of ultraluminous X-ray sources (ULXs) is an open problem in astrophysics. They challenge our current understanding of stellar compact objects and accretion physics. The recent discovery of pulsar ULXs further demonstrates the importance of this intriguing and rare class of objects.
In order to overcome the difficulties of directly studying the optical associations of ULXs, we generally resort in statistical studies of the stellar properties of their host galaxies. We present the largest such study based on the combination of Chandra archival data with the most complete galaxy catalog of the Local Universe. Incorporating robust distances and stellar population parameters based on associated multi-wavelength information, and we explore the association of ULXs with galaxies in the (star formation rate, stellar mass, metallicity) space.
We confirm the known correlation with morphology, star formation rate and stellar mass, while we find an excess of ULXs in dwarf galaxies, indicating dependence on age and metallicity.
When two plasmas collide, their interaction can be mediated by collisionless plasma instabilities or binary collisions between particles of each shell. By comparing the maximum growth rate of the collisionless instabilities with the collision frequency between particles of the shells, we determine the critical density separating the collisionless formation from the collisional formation of the resulting shock waves. This critical density is also the density beyond which the shock downstream is field free, as plasma instabilities do not have time to develop electromagnetic patterns. We further determine the conditions on the shells initial density and velocity for the downstream to be collisional. If these quantities fulfil the determined conditions, the collisionality of the downstream also prevents the shock from accelerating particles or generating strong magnetic fields. We compare the speed of sound with the relative speed of collision between the two shells, thus determining the portion of the parameter space where strong shock formation is possible for both classical and degenerate plasmas. Finally, we discuss the observational consequences in several astrophysical settings.
Tropical forests are three-dimensional spaces with species and resources heterogeneously distributed. The vertical stratification of tropical forest biotas has been observed for several organisms and regions, but, surprisingly, the vertical structuring of large areas of important tropical forests, such as Brazil's Atlantic Forest, remains poorly studied. Here, we addressed the use of different Atlantic Forest strata by bats, comparing ensemble composition and relative abundance between the understorey and the canopy. A total of 618 bats belonging to 31 species and four families were recorded, including 11 species of frugivores and seven species of gleaning insectivores, the two trophic guilds predominantly represented in our sampling. Fifteen species were captured exclusively in the canopy, and six exclusively in the understorey, and many of those species were represented by a low number of captures (<5). The bat species composition, richness and relative abundance between canopy and understorey strata varied. Chiroderma villosum was exclusively captured in the canopy, Artibeus lituratus was netted predominantly in the canopy and Carollia perspicillata and Desmodus rotundus were mostly captured in the understorey. Although processes such as resource partitioning between species and ecomorphological constraints may explain the differential use of forest strata, this remains little understood because of the scarcity of data for the Atlantic forest canopies.
This study examined the role of community resilience and psychological resilience on depressive symptoms in areas on the Mississippi Gulf Coast that have experienced multiple disasters.
Survey administration took place in the spring of 2015 to a spatially stratified, random sample of households. This analysis included a total of 294 subjects who lived in 1 of the 3 counties of the Mississippi Gulf Coast at the time of both Hurricane Katrina in 2005 and the Deepwater Horizon oil spill in 2010. The survey included the Communities Advancing Resilience Toolkit (CART) scale, the Connor-Davidson Resilience Scale (CD-RISC 10), and the Center for Epidemiologic Studies Depression Scale (CES-D).
There was a significant inverse relationship between psychological resilience and depressive symptoms and a significant positive relationship between community resilience and psychological resilience. The results also revealed that community resilience was indirectly related to depressive symptoms through the mediating variable of psychological resilience.
These findings highlight the importance of psychological resilience in long-term disaster recovery and imply that long-term recovery efforts should address factors associated with both psychological and community resilience to improve mental health outcomes. (Disaster Med Public Health Preparedness. 2018;12:241–248)
In plasmas where the mean-free-path is much larger than the size of the system, shock waves can arise with a front much shorter than the mean-free-path. These so-called “collisionless shocks” are mediated by collective plasma interactions. Studies conducted so far on these shocks found that although binary collisions are absent, the distribution functions are thermalized downstream by scattering on the fields, so that magnetohydrodynamics prescriptions may apply. Here we show a clear departure from this pattern in the case of Weibel shocks forming over a flow-aligned magnetic field. A micro-physical analysis of the particle motion in the Weibel filaments shows how they become unable to trap the flow in the presence of too strong a field, inhibiting the mechanism of shock formation. Particle-in-cell simulations confirm these results.
The majority of patients respond to antipsychotic monotherapy at standard doses, but a subset of patients will require more heroic measures that include antipsychotic polypharmacy and high-dose monotherapy. Indeed, research has shown that roughly 30% of patients with psychosis are prescribed multiple antipsychotic medications. We discuss the potential benefits and challenges of these approaches and provide a rationale for why and when they should be utilised.
According to magnetohydrodynamics (MHD), the encounter of two collisional magnetized plasmas at high velocity gives rise to shock waves. Investigations conducted so far have found that the same conclusion still holds in the case of collisionless plasmas. For the case of a flow-aligned field, MHD stipulates that the field and the fluid are disconnected, so that the shock produced is independent of the field. We present a violation of this MHD prediction when considering the encounter of two cold pair plasmas along a flow-aligned magnetic field. As the guiding magnetic field grows, isotropization is progressively suppressed, resulting in a strong influence of the field on the resulting structure. A micro-physics analysis allows us to understand the mechanisms at work. Particle-in-cell simulations also support our conclusions and show that the results are not restricted to a strictly parallel field.