Monodisperse self-assembly in a model with protein-like interactions

We study the self-assembly behaviour of patchy particles with `protein-like' interactions that can be considered as a minimal model for the assembly of viral capsids and other shell-like protein complexes. We thoroughly explore the thermodynamics and dynamics of self assembly as a function of the parameters of the model and find robust assembly of all target structures considered. Optimal assembly occurs in the region of parameter space where a free energy barrier regulates the rate of nucleation, thus preventing the premature exhaustion of the supply of monomers that can lead to the formation of incomplete shells. The interactions also need to be specific enough to prevent the assembly of malformed shells, but whilst maintaining kinetic accessibility. Free-energy landscapes computed for our model have a funnel-like topography guiding the system to form the target structure, and show that the torsional component of the interparticle interactions prevents the formation of disordered aggregates that would otherwise act as kinetic traps.Comment: 11 pages; 10 figure

Impaired Spatial Reorientation in the 3xTg-AD Mouse Model of Alzheimer's Disease.

In early Alzheimer's disease (AD) spatial navigation is impaired; however, the precise cause of this impairment is unclear. Recent evidence suggests that getting lost is one of the first impairments to emerge in AD. It is possible that getting lost represents a failure to use distal cues to get oriented in space. Therefore, we set out to look for impaired use of distal cues for spatial orientation in a mouse model of amyloidosis (3xTg-AD). To do this, we trained mice to shuttle to the end of a track and back to an enclosed start box to receive a water reward. Then, mice were trained to stop in an unmarked reward zone to receive a brain stimulation reward. The time required to remain in the zone for a reward was increased across training, and the track was positioned in a random start location for each trial. We found that 6-month female, but not 3-month female, 6-month male, or 12-month male, 3xTg-AD mice were impaired. 6-month male and female mice had only intracellular pathology and male mice had less pathology, particularly in the dorsal hippocampus. Thus, AD may cause spatial disorientation as a result of impaired use of landmarks

The Lawrence clay of Lawrence County

In cooperation with The Ohio State University Engineering Experiment Station and the Ironton Chamber of Commerce.Published also as Bulletin 67 of the Engineering Experiment Station, The Ohio State University

Foreshock density holes in the context of known upstream plasma structures

We present case examples of foreshock density holes and results from a statistical survey, which provide additional characterizations of these recently-described structures. Specific effort is made to place these objects into context with well-studied foreshock phenomena, such as hot flow anomalies (HFAs) and large-amplitude magnetic pulsations (SLAMS). Density holes are observed during higher-than-average solar wind speeds (~620 km s<sup>−1</sup>), have well-correlated density and magnetic field intensities, and anti-correlated density and temperature variations. Like HFAs, these structures occur over a wide range of foreshock geometries, suggesting that this is not a determining factor. They are embedded within IMF current sheets, but their cross-structure magnetic shears are considerably lower than for HFAs. When the Cluster spacecraft are widely separated, they are able to measure structure time development, with substantial changes occurring over 10s of seconds, confirming an earlier case study, and possibly indicating short lifetimes as well. We find that density holes can occur in the absence of strong upstream magnetic pulsations and/or density enhancements, which rules out a "wake effect" as the sole explanation for their formation. Most important is the observation that the observed solar wind motional electric fields tend to have components pointing away from the embedding IMF current sheets. Density holes have no connection with magnetic holes and foreshock cavities, and appear not to be early-stage or weakly-formed HFAs

The self-assembly and evolution of homomeric protein complexes

We introduce a simple "patchy particle" model to study the thermodynamics and dynamics of self-assembly of homomeric protein complexes. Our calculations allow us to rationalize recent results for dihedral complexes. Namely, why evolution of such complexes naturally takes the system into a region of interaction space where (i) the evolutionarily newer interactions are weaker, (ii) subcomplexes involving the stronger interactions are observed to be thermodynamically stable on destabilization of the protein-protein interactions and (iii) the self-assembly dynamics are hierarchical with these same subcomplexes acting as kinetic intermediates.Comment: 4 pages, 4 figure

Energy-dispersed ions in the plasma sheet boundary layer and associated phenomena: Ion heating, electron acceleration, Alfvén waves, broadband waves, perpendicular electric field spikes, and auroral emissions.

Recent Cluster studies reported properties of multiple energy-dispersed ion structures in the plasma sheet boundary layer (PSBL) that showed substructure with several well separated ion beamlets, covering energies from 3 keV up to 100 keV (Keiling et al., 2004a, b). Here we report observations from two PSBL crossings, which show a number of identified one-to-one correlations between this beamlet substructure and several plasma-field characteristics: (a) bimodal ion conics (<1 keV), (b) field-aligned electron flow (<1 keV), (c) perpendicular electric field spikes (~20 mV/m), (d) broadband electrostatic ELF wave packets (<12.5 Hz), and (e) enhanced broadband electromagnetic waves (<4 kHz). The one-to-one correlations strongly suggest that these phenomena were energetically driven by the ion beamlets, also noting that the energy flux of the ion beamlets was 1–2 orders of magnitude larger than, for example, the energy flux of the ion outflow. In addition, several more loosely associated correspondences were observed within the extended region containing the beamlets: (f) electrostatic waves (BEN) (up to 4 kHz), (g) traveling and standing ULF Alfvén waves, (h) field-aligned currents (FAC), and (i) auroral emissions on conjugate magnetic field lines. Possible generation scenarios for these phenomena are discussed. In conclusion, it is argued that the free energy of magnetotail ion beamlets drove a variety of phenomena and that the spatial fine structure of the beamlets dictated the locations of where some of these phenomena occurred. This emphasizes the notion that PSBL ion beams are important for magnetosphere-ionosphere coupling. However, it is also shown that the dissipation of electromagnetic energy flux (at altitudes below Cluster) of the simultaneously occurring Alfvén waves and FAC was larger (FAC being the largest) than the dissipation of beam kinetic energy flux, and thus these two energy carriers contributed more to the energy transport on PSBL field lines from the distant magnetotail to the ionosphere than the ion beams

Geometric frustration in small colloidal clusters

We study the structure of clusters in a model colloidal system with competing interactions using Brownian dynamics simulations. A short-ranged attraction drives clustering, while a weak, long-ranged repulsion is used to model electrostatic charging in experimental systems. The former is treated with a short-ranged Morse attractive interaction, the latter with a repulsive Yukawa interaction. We consider the yield of clusters of specific structure as a function of the strength of the interactions, for clusters with m=3,4,5,6,7,10 and 13 colloids. At sufficient strengths of the attractive interaction (around 10 kT), the average bond lifetime approaches the simulation timescale and the system becomes nonergodic. For small clusters m<=5 where geometric frustration is not relevant, despite nonergodicity, for sufficient strengths of the attractive interaction the yield of clusters which maximise the number of bonds approaches 100%. However for $m=7$ and higher, in the nonergodic regime we find a lower yield of these structures where we argue geometric frustration plays a significant role. $m=6$ is a special case, where two structures, of octahedral and C2v symmetry compete, with the latter being favoured by entropic contributions in the ergodic regime and by kinetic trapping in the nonergodic regime. We believe that our results should be valid as far as the one-component description of the interaction potential is valid. A system with competing electrostatic repulsions and van der Waals attractions may be such an example. However, in some cases, the one-component description of the interaction potential may not be appropriate.Comment: 21 pages, accepted for publication by J. Phys. Condens. Matte

SEROPREVALENCIA DE Toxoplasma gondii EN LLAMAS DE DOS FUNDOS GANADEROS DE LA PROVINCIA DE MELGAR, PUNO

El objetivo del estudio fue determinar la seroprevalencia del Toxoplasma gondii en llamas hembras de dos fundos ganaderos de la provincia de Melgar, Puno. Se colectaron sueros sanguíneos de 284 animales para la detección de anticuerpos mediante el método de Inmunofluorescencia Indirecta (IFI). El 47.5 ± 5.8% (135/284) del total de las muestras presentaron anticuerpos. La frecuencia de reactores se incrementó en relación directa con la edad de los animales (nacimiento-2 años: 33.8 ± 11.0%; &gt;2 a 4 años: 51.2 ± 10.8; &gt;4 a 6 años: 56.8 ± 14.6%; y &gt;6 años: 50.6 ± 10.5%). Se encontraron diferencias estadísticas (p&lt;0.05) en la frecuencia de reactores entre fundos. Además, se halló que la variable edad y zona de muestreo representan un factor de riesgo para la infección con T. gondii (p&lt;0.0001).The aim of this study was to determine the seroprevalence of Toxoplasma gondii in female llamas from two farms located in the Melgar province, Puno. A total of 284 blood samples were tested using the indirect immunofluorescence test (IFAT) to detect antibodies against T. gondii. The results showed that 47.5 + 5.8% (135/284) of the samples had antibodies and they increased with age. The seroprevalence from birth till 2 years, 2- 4 years, &gt;4-6 years, and &gt;6 years was 33.8 ± 11.0, 51.2 ± 10.8, 56.8 ± 14.6, and 50.6 ± 10.5%, respectively. There were significant differences (p&lt;0.05) in the frecuency of female reactors between farms. Age and farm variables were considered as risk factors for the infection with Toxoplasma gondii (p&lt;0.0001)

Interaction of egocentric and world-centered reference frames in the rat posterior parietal cortex

Sherpa Romeo yellow journal. Open access article. Creative Commons Attribution-Noncommercial-ShareAlike 3.0 Unported License (CC BY-NC-SA 3.0) applies.Navigation requires coordination of egocentric and allocentric spatial reference frames and may involve vectorial computations relative to landmarks. Creation of are presentation of target heading relative to landmarks could be accomplished from neurons that encode the conjunction of egocentric landmark bearings with allocentric head direction. Landmark vector representations could then be created by combining these cells with distance encoding cells. Landmark vector cells have been identified in rodent hippocampus. Given remembered vectors at go allocations, it would be possible to use such cells to compute trajectories to hidden goals. To look for the first stage in this process, we assessed parietal cortical neuralactivity as a function of egocentric cue light location and allocentric head direction in rats running a random sequence to light locations around a circular platform. We identified cells that exhibit the predicted egocentric-by allocentric conjunctive characteristics and anticipate orienting toward the goal.Ye

Increasing HPV Vaccination in a Network of Pediatric Clinics using a Multi-component Approach

Background: Despite continued public health efforts to increase human papillomavirus (HPV) vaccination among adolescents, initiation remains below the level needed to reach the Healthy People 2020 goal of 80% series completion by age 13. Methods: We developed, implemented, and evaluated a multi-component program that used evidence-based strategies to increase HPV vaccine initiation in a network of 51 pediatric clinics in Houston, Texas. Our target populations were the clinic network, healthcare providers, male and female patients ages 11-17, and their parents. The program, called the Adolescent Vaccination Program (AVP), was conducted from March 2016 through March 2019 and contained strategies to increase vaccination including: HPV immunization champions; provider assessment and feedback; provider continuing education; provider reminders; and patient reminders. We used a single group pre/post design with an external comparison – NIS-Teen. Our primary outcome was initiation of the HPV vaccine based on the electronic health record. We used interrupted time series analysis (ITSA) to measure change in initiation over time. We calculated monthly, quarterly, and annual rates of initiation for each physician, clinic, and the network. We examined patterns of initiation by patient age, sex, race/ethnicity, and type of insurance. Results: By the end of the project, the 51 clinics averaged 77.4% initiation. Rates increased annually from September 2015 through March 2019. ITSA analysis over 75 months showed an increase in vaccine initiation of 0.396% per month from the introduction of the program in March 2016. Average individual clinic improvement was 0.37% per month ranging from -0.04% to 0.68% through March 2019. Data for the 11-12 year olds, the target age group for initiating the vaccine, showed a greater percentage increase (54.2%) compared with the 13-17 year olds (29.6%). Hispanics and African Americans had the highest initiation rates in all years while non-Hispanic whites had the lowest. Families without insurance had the lowest rates while those with Medicaid/Medicare had the highest. Conclusions: We observed a secular trend upward in both the network and NIS-Teen data; however, the network showed a steeper increase. The AVP is a promising program of strategies to increase HPV vaccination in a clinic setting