Modified Gravity Makes Galaxies Brighter

We investigate the effect of modifed gravity with screening mechanisms, such as the chameleon or symmetron models, upon the structure of main sequence stars. We find that unscreened stars can be significantly more luminous and ephemeral than their screened doppelgangers. By embedding these stars into dwarf galaxies, which can be unscreened for values of the parameters not yet ruled out observationally, we show that the cumulative effect of their increased luminosity can enhance the total galactic luminosity. We estimate this enhancement and find that it can be considerable given model parameters that are still under experimental scrutiny. By looking for systematic offsets between screened dwarf galaxies in clusters and unscreened galaxies in voids, these effects could form the basis of an independent observational test that can potentially lower the current experimental bounds on the model independent parameters of these theories by and order of magnitude or more.Comment: 16 pages, six figure

The Non-Credible Score of the Rey Auditory Verbal Leaming Test: Is It Better at Predicting Non-Credible Neuropsychological Test Performance Than the RAVLT Recognition Score?

The ability of both the non-credible score of the Rey Auditory Verbal Learning Test (RAVLT NC) and the recognition score of the RAVLT (RAVLT Recog) to predict credible versus non-credible neuropsychological test performance was examined. Credible versus non-credible group membership was determined according to diagnostic criteria with consideration of performance on two stand-alone performance validity tests. Findings from this retrospective data analysis of outpatients seen for neuropsychological testing within a Veterans Affairs Medical Center (N = 175) showed that RAVLT Recog demonstrated better classification accuracy than RAVLT NC in predicting credible versus non-credible neuropsychological test performance. Specifically, an RAVLT Recog cutoff of ≤9 resulted in reasonable sensitivity (48%) and acceptable specificity (91%) in predicting non-credible neuropsychological test performance. Implications for clinical practice are discussed. Note: The views contained here within are those of the authors and not representative of the institutions with which they are associated

A Direct Manipulation Language for Explaining Algorithms

Instructors typically explain algorithms in computer science by tracing their behavior, often on blackboards, sometimes with algorithm visualizations. Using blackboards can be tedious because they do not facilitate manipulation of the drawing, while visualizations often operate at the wrong level of abstraction or must be laboriously hand-coded for each algorithm. In response, we present a direct manipulation (DM) language for explaining algorithms by manipulating visualized data structures. The language maps DM gestures onto primitive program behaviors that occur in commonly taught algorithms. We performed an initial evaluation of the DM language on teaching assistants of an undergraduate algorithms class, who found the language easier to use and more helpful for explaining algorithms than a standard drawing application (GIMP)

On the Gains to International Trade in Risky Financial Assets

This paper develops and implements a framework for quantifying the gains to international trade in risky financial assets. The framework can handle may agents, many assets, incomplete markets and limited participation in asset markets. It delivers closed-form analytic solutions for consumption, portfolio allocations, asset prices and the gains to trade. We find enormous gains to trade when asset returns are calibrated to observed risk premia and all agents participate in asset markets. The gains-to-trade puzzle is closely related to, but distinct from, the equity premium puzzle. High risk aversion merely alters the form of the gains-to-trade puzzle, but limited participation in asset markets goes a long way towards addressing both puzzles. We also identify three reasons for limited international risk sharing. First, the requirement that asset markets span the space of national output shocks fails in a serious way. Second, for many countries the cost of using financial assets to hedge national output shocks greatly exceeds the benefits. Third, limited asset market participation reduces the feasible gains from international risk sharing.

MARS Science Laboratory Post-Landing Location Estimation Using Post2 Trajectory Simulation

The Mars Science Laboratory (MSL) Curiosity rover landed safely on Mars August 5th, 2012 at 10:32 PDT, Earth Received Time. Immediately following touchdown confirmation, best estimates of position were calculated to assist in determining official MSL locations during entry, descent and landing (EDL). Additionally, estimated balance mass impact locations were provided and used to assess how predicted locations compared to actual locations. For MSL, the Program to Optimize Simulated Trajectories II (POST2) was the primary trajectory simulation tool used to predict and assess EDL performance from cruise stage separation through rover touchdown and descent stage impact. This POST2 simulation was used during MSL operations for EDL trajectory analyses in support of maneuver decisions and imaging MSL during EDL. This paper presents the simulation methodology used and results of pre/post-landing MSL location estimates and associated imagery from Mars Reconnaissance Orbiter s (MRO) High Resolution Imaging Science Experiment (HiRISE) camera. To generate these estimates, the MSL POST2 simulation nominal and Monte Carlo data, flight telemetry from onboard navigation, relay orbiter positions from MRO and Mars Odyssey and HiRISE generated digital elevation models (DEM) were utilized. A comparison of predicted rover and balance mass location estimations against actual locations are also presented

Assessment of the Mars Science Laboratory Entry, Descent, and Landing Simulation

On August 5, 2012, the Mars Science Laboratory rover, Curiosity, successfully landed inside Gale Crater. This landing was only the seventh successful landing and fourth rover to be delivered to Mars. Weighing nearly one metric ton, Curiosity is the largest and most complex rover ever sent to investigate another planet. Safely landing such a large payload required an innovative Entry, Descent, and Landing system, which included the first guided entry at Mars, the largest supersonic parachute ever flown at Mars, and a novel and untested Sky Crane landing system. A complete, end-to-end, six degree-of-freedom, multi-body computer simulation of the Mars Science Laboratory Entry, Descent, and Landing sequence was developed at the NASA Langley Research Center. In-flight data gathered during the successful landing is compared to pre-flight statistical distributions, predicted by the simulation. These comparisons provide insight into both the accuracy of the simulation and the overall performance of the vehicle

Lack of interferon response in animals to naked siRNAs

RNA interference (RNAi) is rapidly becoming the method of choice for the elucidation of gene function and the identification of drug targets. As with other oligonucleotide-based strategies, RNAi is envisioned to ultimately be useful as a human therapeutic. Unlike previous nucleic acid therapeutics, small interfering RNAs have the potential to elicit immune responses via interactions with Toll-like receptor 3 and trigger interferon responses like long, double-stranded RNA and its analogs, such as poly(I:C). Recently, the safety of siRNAs has been questioned because they have been shown to trigger an interferon response in cultured cells. We show here that it is possible to administer naked, synthetic siRNAs to mice and downregulate an endogenous or exogenous target without inducing an interferon response

Factors to Consider in Improving Prescription Drug Pharmacy Leaflets

Today, when consumers receive prescription drug pharmacy leaflets (also known as ‘consumer medication information’ or CMI), they often appear in small font size, with cluttered layouts, and distracting information. This problem has attracted the attention of the U.S. Food and Drug Administration in advocating for more comprehendible, accurate, and easy-to-access CMI formats. Our study of four different CMI prototypes shows that an expanded Over-the-Counter (OTC) Drug Facts prototype is the best for improving comprehension accuracy, and is especially effective for those with lower health literacy and health motivation. A simpler OTC prototype did not aid accuracy scores due in part to its lack of complexity; whereas the most complex prototype (the revised medication guide – similar to most CMI today) reduced leaflet likability and usage intentions. Finally, continued leaflet availability improved accuracy scores for lower health literacy and health motivation respondents. Implications for marketing and public health policy are offered

Computational prediction of essential genes in an unculturable endosymbiotic bacterium, Wolbachia of Brugia malayi

<p>Abstract</p> <p>Background</p> <p><it>Wolbachia </it>(<it>w</it>Bm) is an obligate endosymbiotic bacterium of <it>Brugia malayi</it>, a parasitic filarial nematode of humans and one of the causative agents of lymphatic filariasis. There is a pressing need for new drugs against filarial parasites, such as <it>B. malayi</it>. As <it>w</it>Bm is required for <it>B. malayi </it>development and fertility, targeting <it>w</it>Bm is a promising approach. However, the lifecycle of neither <it>B. malayi </it>nor <it>w</it>Bm can be maintained <it>in vitro</it>. To facilitate selection of potential drug targets we computationally ranked the <it>w</it>Bm genome based on confidence that a particular gene is essential for the survival of the bacterium.</p> <p>Results</p> <p><it>w</it>Bm protein sequences were aligned using BLAST to the Database of Essential Genes (DEG) version 5.2, a collection of 5,260 experimentally identified essential genes in 15 bacterial strains. A confidence score, the Multiple Hit Score (MHS), was developed to predict each <it>w</it>Bm gene's essentiality based on the top alignments to essential genes in each bacterial strain. This method was validated using a jackknife methodology to test the ability to recover known essential genes in a control genome. A second estimation of essentiality, the Gene Conservation Score (GCS), was calculated on the basis of phyletic conservation of genes across <it>Wolbachia's </it>parent order <it>Rickettsiales</it>. Clusters of orthologous genes were predicted within the 27 currently available complete genomes. Druggability of <it>w</it>Bm proteins was predicted by alignment to a database of protein targets of known compounds.</p> <p>Conclusion</p> <p>Ranking <it>w</it>Bm genes by either MHS or GCS predicts and prioritizes potentially essential genes. Comparison of the MHS to GCS produces quadrants representing four types of predictions: those with high confidence of essentiality by both methods (245 genes), those highly conserved across <it>Rickettsiales </it>(299 genes), those similar to distant essential genes (8 genes), and those with low confidence of essentiality (253 genes). These data facilitate selection of <it>w</it>Bm genes for entry into drug design pipelines.</p

Gene Expression Pattern Analysis of Anterior Hox Genes during Zebrafish (Danio rerio) Embryonic Development Reveals Divergent Expression Patterns from Other Teleosts

The regional identity of organs and organ systems along the anterior-posterior axis during embryonic development is patterned, in part, by Hox genes, which encode transcription factor proteins that activate or repress the expression of downstream target genes. Divergent nested Hox gene expression patterns may have had a role in facilitating morphological divergence of structures, such as the pharyngeal jaw apparatus, among evolutionarily divergent teleost fishes. Recent studies from several evolutionarily divergent teleosts, such as the Japanese Medaka (Oryzias latipes) and the Nile Tilapia (Oreochromis niloticus), have shown the presence of divergent expression patterns of several Hox genes within paralog groups 2–5 between these species. Specifically, these expression patterns were documented in the pharyngeal arches, which give rise to the pharyngeal jaw apparatus. While the expression patterns of several Zebrafish (Danio rerio) Hox genes that are orthologous to those of Medaka and Tilapia have been documented within the developing hindbrain and pharyngeal arches, many still have yet to be documented, especially within the pharyngeal arches during the postmigratory cranial neural crest cell stages. Here, we present the expression patterns of six Zebrafish Hox genes, hoxc3a, d3a, a4a, d4a, b5a, and c5a, within the pharyngeal arches during a postmigratory cranial neural crest cell stage and compare them to their orthologous genes of Medaka and Tilapia at similar stages. We show that while hoxc3a, d3a, and c5a of Zebrafish are absent from the pharyngeal arches, hoxa4a, d4a, and b5a show divergent expression patterns from their orthologs in Medaka and Tilapia. These observed divergences may be, in part, responsible for the divergent pharyngeal jaw apparatus structures exhibited by these fishes