Molecular Model of the Microvillar Cytoskeleton and Organization of the Brush Border

BACKGROUND. Brush border microvilli are ~1-µm long finger-like projections emanating from the apical surfaces of certain, specialized absorptive epithelial cells. A highly symmetric hexagonal array of thousands of these uniformly sized structures form the brush border, which in addition to aiding in nutrient absorption also defends the large surface area against pathogens. Here, we present a molecular model of the protein cytoskeleton responsible for this dramatic cellular morphology. METHODOLOGY/PRINCIPAL FINDINGS. The model is constructed from published crystallographic and microscopic structures reported by several groups over the last 30+ years. Our efforts resulted in a single, unique, self-consistent arrangement of actin, fimbrin, villin, brush border myosin (Myo1A), calmodulin, and brush border spectrin. The central actin core bundle that supports the microvillus is nearly saturated with fimbrin and villin cross-linkers and has a density similar to that found in protein crystals. The proposed model accounts for all major proteinaceous components, reproduces the experimentally determined stoichiometry, and is consistent with the size and morphology of the biological brush border membrane. CONCLUSIONS/SIGNIFICANCE. The model presented here will serve as a structural framework to explain many of the dynamic cellular processes occurring over several time scales, such as protein diffusion, association, and turnover, lipid raft sorting, membrane deformation, cytoskeletal-membrane interactions, and even effacement of the brush border by invading pathogens. In addition, this model provides a structural basis for evaluating the equilibrium processes that result in the uniform size and structure of the highly dynamic microvilli.Boston University (Graduate Student Research Fellowship); National Institutes of Health (GM62886

The Directional Dependence of Apertures, Limits and Sensitivity of the Lunar Cherenkov Technique to a UHE Neutrino Flux

We use computer simulations to obtain the directional-dependence of the lunar Cherenkov technique for ultra-high energy (UHE) neutrino detection. We calculate the instantaneous effective area of past lunar Cherenkov experiments as a function of neutrino arrival direction, and hence the directional-dependence of the combined limit imposed by GLUE and the experiment at Parkes. We also determine the directional dependence of the aperture of future planned experiments with ATCA, ASKAP and the SKA to a UHE neutrino flux, and calculate the potential annual exposure to astronomical objects as a function of angular distance from the lunar trajectory through celestial coordinates.Comment: 17 pages, 7 figures; Submitted to Astroparticle Physic

Homo Datumicus : correcting the market for identity data

Effective digital identity systems offer great economic and civic potential. However, unlocking this potential requires dealing with social, behavioural, and structural challenges to efficient market formation. We propose that a marketplace for identity data can be more efficiently formed with an infrastructure that provides a more adequate representation of individuals online. This paper therefore introduces the ontological concept of Homo Datumicus: individuals as data subjects transformed by HAT Microservers, with the axiomatic computational capabilities to transact with their own data at scale. Adoption of this paradigm would lower the social risks of identity orientation, enable privacy preserving transactions by default and mitigate the risks of power imbalances in digital identity systems and markets

Attribution of intentional causation influences the perception of observed movements: behavioral evidence and neural correlates

Recent research on human agency suggests that intentional causation is associated with a subjective compression in the temporal interval between actions and their effects. That is, intentional movements and their causal effects are perceived as closer together in time than equivalent unintentional movements and their causal effects. This so-called intentional binding effect is consistently found for one's own self-generated actions. It has also been suggested that intentional binding occurs when observing intentional movements of others. However, this evidence is undermined by limitations of the paradigm used. In the current study we aimed to overcome these limitations using a more rigorous design in combination with functional Magnetic Resonance Imaging (fMRI) to explore the neural underpinnings of intentional binding of observed movements. In particular, we aimed to identify brain areas sensitive to the interaction between intentionality and causality attributed to the observed action. Our behavioral results confirmed the occurrence of intentional binding for observed movements using this more rigorous paradigm. Our fMRI results highlighted a collection of brain regions whose activity was sensitive to the interaction between intentionality and causation. Intriguingly, these brain regions have previously been implicated in the sense of agency over one's own movements. We discuss the implications of these results for intentional binding specifically, and the sense of agency more generally

REGIONAL COST SHARE NECESSARY FOR RANCHER PARTICIPATION IN BRUSH CONTROL

Large-scale brush-control programs are being proposed in Texas to increase off-site water yields. Biophysical and economic simulation models are combined to estimate the effects of brush control on representative ranches in four ecological regions of the Edwards Plateau area of Texas. Net present values of representative ranches in three of four regions decrease with brush control. Cost shares necessary for ranches from the three regions to break even range from 7% to 31% of total brush-control costs. Any large-scale brush-control program will therefore require a substantial investment by the state of Texas.Agribusiness,

Robustness of Regularity for the 33D Convective Brinkman-Forchheimer Equations

We prove a robustness of regularity result for the $3$D convective Brinkman-Forchheimer equations \partial_tu -\mu\Delta u + (u \cdot \nabla)u + \nabla p + \alpha u + \beta\abs{u}^{r - 1}u = f, for the range of the absorption exponent $r \in [1, 3]$ (for $r > 3$ there exist global-in-time regular solutions), i.e. we show that strong solutions of these equations remain strong under small enough changes of the initial condition and forcing function. We provide a smallness condition which is similar to the robustness conditions given for the $3$D incompressible Navier-Stokes equations by Chernyshenko et al. (2007) and Dashti & Robinson (2008).Comment: 22 page

Nonscanning climate sensor study

The Nonscanning Climate Sensor represents a new instrument for climate research and global monitoring of the earth radiation budget. It contains a mosaic of array of detectors which measures the outgoing radiation of the earth in all directions without the need for mechanical scanning. The goal is to eliminate all moving parts and obtain highly calibrated measurements for up to one solar cycle (11 years) without being susceptible to mechanical failure. Over set intervals of time, the angular measurements are integrated up to produce total reflected and emitted flux values from each target area on the Earth. To achieve the require sensitivity while maintaining a flat spectral response, an improved dual cavity detector with digital control loop was developed. The detector is self calibrating to maintain high precision over the life of the instrument. Prototype detectors and a complete set of electronics with a microprocessor controller were fabricated and tested. Measurements show that the new detectors are more than an order of magnitude more sensitive than previous versions