Geophysical Exploration of Vesta

Dawn’s year-long stay at Vesta allows comprehensive mapping of the shape, topography, geology, mineralogy, elemental abundances, and gravity field using it’s three instruments and highprecision spacecraft navigation. In the current Low Altitude Mapping Orbit (LAMO), tracking data is being acquired to develop a gravity field expected to be accurate to degree and order ~20 [1, 2]. Multi-angle imaging in the Survey and High Altitude Mapping Orbit (HAMO) has provided adequate stereo coverage to develop a shape model accurate to ~10 m at 100 m horizontal spatial resolution. Accurate mass determination combined with the shape yields a more precise value of bulk density, albeit with some uncertainty resulting from the unmeasured seasonally-dark north polar region. The shape and gravity of Vesta can be used to infer the interior density structure and investigate the nature of the crust, informing models for Vesta’s formation and evolution

Energy-Based Models for Anomaly Detection: A Manifold Diffusion Recovery Approach

We present a new method of training energy-based models (EBMs) for anomaly detection that leverages low-dimensional structures within data. The proposed algorithm, Manifold Projection-Diffusion Recovery (MPDR), first perturbs a data point along a low-dimensional manifold that approximates the training dataset. Then, EBM is trained to maximize the probability of recovering the original data. The training involves the generation of negative samples via MCMC, as in conventional EBM training, but from a different distribution concentrated near the manifold. The resulting near-manifold negative samples are highly informative, reflecting relevant modes of variation in data. An energy function of MPDR effectively learns accurate boundaries of the training data distribution and excels at detecting out-of-distribution samples. Experimental results show that MPDR exhibits strong performance across various anomaly detection tasks involving diverse data types, such as images, vectors, and acoustic signals.Comment: NeurIPS 202

Size-assortative mating and sexual size dimorphism are predictable from simple mechanics of mate-grasping behavior

<p>Abstract</p> <p>Background</p> <p>A major challenge in evolutionary biology is to understand the typically complex interactions between diverse counter-balancing factors of Darwinian selection for size assortative mating and sexual size dimorphism. It appears that rarely a simple mechanism could provide a major explanation of these phenomena. Mechanics of behaviors can predict animal morphology, such like adaptations to locomotion in animals from various of taxa, but its potential to predict size-assortative mating and its evolutionary consequences has been less explored. Mate-grasping by males, using specialized adaptive morphologies of their forelegs, midlegs or even antennae wrapped around female body at specific locations, is a general mating strategy of many animals, but the contribution of the mechanics of this wide-spread behavior to the evolution of mating behavior and sexual size dimorphism has been largely ignored.</p> <p>Results</p> <p>Here, we explore the consequences of a simple, and previously ignored, fact that in a grasping posture the position of the male's grasping appendages relative to the female's body is often a function of body size difference between the sexes. Using an approach taken from robot mechanics we model coercive grasping of females by water strider <it>Gerris gracilicornis </it>males during mating initiation struggles. We determine that the male optimal size (relative to the female size), which gives the males the highest grasping force, properly predicts the experimentally measured highest mating success. Through field sampling and simulation modeling of a natural population we determine that the simple mechanical model, which ignores most of the other hypothetical counter-balancing selection pressures on body size, is sufficient to account for size-assortative mating pattern as well as species-specific sexual dimorphism in body size of <it>G. gracilicornis</it>.</p> <p>Conclusion</p> <p>The results indicate how a simple and previously overlooked physical mechanism common in many taxa is sufficient to account for, or importantly contribute to, size-assortative mating and its consequences for the evolution of sexual size dimorphism.</p

Magnetic phenomena at and near nu =1/2 and 1/4: theory, experiment and interpretation

I show that the hamiltonian theory of Composite Fermions (CF) is capable of yielding a unified description in fair agreement with recent experiments on polarization P and relaxation rate 1/T_1 in quantum Hall states at filling nu = p/(2ps+1), at and near nu = 1/2 and 1/4, at zero and nonzero temperatures. I show how rotational invariance and two dimensionality can make the underlying interacting theory behave like a free one in a limited context.Comment: Latex 4 pages, 2 figure

Intradiscal injection of simvastatin retards progression of intervertebral disc degeneration induced by stab injury

Abstract Introduction Earlier work indicates that the cholesterol-lowering drug, simvastatin, is anabolic to chondrogenic expression of rat intervertebral disc (IVD) cells, which suggests a potential role for simvastatin in IVD regeneration. In this study, we expand on our earlier work to test the effectiveness of simvastatin on disc degeneration utilizing a rat tail disc degeneration model. Methods 30 rats that underwent 21 G needle-puncture at rat tail discs were injected with simvastatin-loaded poly(ethylene glycol)-poly(lactic acid-co-glycolic acid)-poly(ethylene glycol) (PEG-PLGA-PEG) gel (5 mg/ml) or vehicle control at 4 weeks after needle injury. All animals were sacrificed 2 weeks after simvastatin injection. Bone morphogenetic protein-2 (BMP-2), aggrecan, collagen type II, and collagen type I messenger ribonucleic acid (mRNA) expression in the rat nucleus pulposus (NP) were measured by real-time polymerase chain reaction (PCR). In vivo magnetic resonance imaging (MRI) was performed to monitor changes in disc degeneration. Rat discs were also assessed by histology using hematoxylin and eosin (H&E) and safranin O staining. In addition, the NP weight, glycosaminoglycan (sGAG) and DNA content were also measured. Results A single dose of simvastatin loaded in thermo-sensitive PEG-PLGA-PEG gel injected into the NP had the trend to increase aggrecan expression and sGAG content, and significantly increased mRNA levels of BMP-2, collagen type II, and the differentiation index (the ratio of collagen type II to collagen type I). The decreased NP weight, T2 intensity, as well as MRI index in the rat tail discs induced by needle puncture were significantly reversed after 2 weeks of simvastatin treatment. In addition, simvastatin treatment also improved histological changes induced by needle puncture. Conclusions A single injection of simvastatin loaded in PEG-PLGA-PEG gel into rat tail discs had the potential to retard or regenerate the degenerative disc.http://deepblue.lib.umich.edu/bitstream/2027.42/112803/1/13075_2009_Article_2698.pd

Orochi: Investigating Requirements and Expectations for Multipurpose Daily Used Supernumerary Robotic Limbs

Supernumerary robotic limbs (SRLs) present many opportunities for daily use. However, their obtrusiveness and limitations in interaction genericity hinder their daily use. To address challenges of daily use, we extracted three design considerations from previous literature and embodied them in a wearable we call Orochi. The considerations include the following: 1) multipurpose use, 2) wearability by context, and 3) unobtrusiveness in public. We implemented Orochi as a snake-shaped robot with 25 DoFs and two end effectors, and demonstrated several novel interactions enabled by its limber design. Using Orochi, we conducted hands-on focus groups to explore how multipurpose SRLs are used daily and we conducted a survey to explore how they are perceived when used in public. Participants approved Orochi's design and proposed different use cases and postures in which it could be worn. Orochi's unobtrusive design was generally well received, yet novel interactions raise several challenges for social acceptance. We discuss the significance of our results by highlighting future research opportunities based on the design, implementation, and evaluation of Orochi

Expressiveness modulo Bisimilarity of Regular Expressions with Parallel Composition (Extended Abstract)

The languages accepted by finite automata are precisely the languages denoted by regular expressions. In contrast, finite automata may exhibit behaviours that cannot be described by regular expressions up to bisimilarity. In this paper, we consider extensions of the theory of regular expressions with various forms of parallel composition and study the effect on expressiveness. First we prove that adding pure interleaving to the theory of regular expressions strictly increases its expressiveness up to bisimilarity. Then, we prove that replacing the operation for pure interleaving by ACP-style parallel composition gives a further increase in expressiveness. Finally, we prove that the theory of regular expressions with ACP-style parallel composition and encapsulation is expressive enough to express all finite automata up to bisimilarity. Our results extend the expressiveness results obtained by Bergstra, Bethke and Ponse for process algebras with (the binary variant of) Kleene's star operation.Comment: In Proceedings EXPRESS'10, arXiv:1011.601

b -> s gamma in the left-right supersymmetric model

The rare decay $b \to s \gamma$ is studied in the left-right supersymmetric model. We give explicit expressions for all the amplitudes associated with the supersymmetric contributions coming from gluinos, charginos and neutralinos in the model to one-loop level. The branching ratio is enhanced significantly compared to the standard model and minimal supersymmetric standard model values by contributions from the right-handed gaugino and squark sector. We give numerical results coming from the leading order contributions. If the only source of flavor violation comes from the CKM matrix, we constrain the scalar fermion-gaugino sector. If intergenerational mixings are allowed in the squark mass matrix, we constrain such supersymmetric sources of flavor violation. The decay $b \to s \gamma$ sets constraints on the parameters of the model and provides distinguishing signs from other supersymmetric scenarios.Comment: 12 figure

Selection of tuning parameters in bridge regression models via Bayesian information criterion

We consider the bridge linear regression modeling, which can produce a sparse or non-sparse model. A crucial point in the model building process is the selection of adjusted parameters including a regularization parameter and a tuning parameter in bridge regression models. The choice of the adjusted parameters can be viewed as a model selection and evaluation problem. We propose a model selection criterion for evaluating bridge regression models in terms of Bayesian approach. This selection criterion enables us to select the adjusted parameters objectively. We investigate the effectiveness of our proposed modeling strategy through some numerical examples.Comment: 20 pages, 5 figure