Low Thrust Trajectory Design for CRAFTI

The Canadian Robotic Asteroid Flyby and (Tentatively) Impact project (CRAFTI) proposes to accomplish an interplanetary mission to explore an asteroid while maintaining a budget of ~US$10 million. This cost target implies a launch as a secondary payload and hence a microsatsized spacecraft. The mission objective is to send two spacecraft to encounter the near-Earth asteroid Toutatis in 2008; one of these will fly by Toutatis at close range, while the other impacts the asteroid. An electric propulsion system is being considered to provide the thrust for the orbital manoeuvres. However, the thrust level achievable by this kind of system is very low, requiring long burn times that complicate the orbital analysis. A lowthrust orbit propagator that has been developed to support the CRAFTI mission analysis, and the preliminary trajectory design work that has been carried out, is described in this paper

Uncovering a Role for SK2 in Angelman Syndrome

Angelman syndrome is a severe neurodevelopmental disorder caused by mutations in UBE3A. Sun et al. (2015) report SK2 as a UBE3A substrate and provide insight into the molecular mechanisms that might underlie impaired neuronal function in individuals affected by Angelman syndrome

Tropical Geometry and the Motivic Nearby Fiber

We construct motivic invariants of a subvariety of an algebraic torus from its tropicalization and initial degenerations. More specifically, we introduce an invariant of a compactification of such a variety called the "tropical motivic nearby fiber." This invariant specializes in the schon case to the Hodge-Deligne polynomial of the limit mixed Hodge structure of a corresponding degeneration. We give purely combinatorial expressions for this Hodge-Deligne polynomial in the cases of schon hypersurfaces and smooth tropical varieties. We also deduce a formula for the Euler characteristic of a general fiber of the degeneration.Comment: 27 pages. Compositio Mathematica, to appea

Estimates of Land Ice Changes from Sea Level and Gravity Observations

Understanding how global ice volume on the Earth has changed is of significant importance to improving our understanding of the climate system. Fortunately, the geographically unique perturbations in sea level that result from rapid changes in the mass of, otherwise difficult to measure, land-ice reservoirs can be used to infer the sources and magnitude of melt water. We explore the history of land-ice mass changes through the effect that these mass fluxes have had on both global and regional gravity and sea-level fields.Earth and Planetary Science

Crx, a Novel otx-like Homeobox Gene, Shows Photoreceptor-Specific Expression and Regulates Photoreceptor Differentiation

AbstractWe have isolated a novel otx-like homeobox gene, Crx, from the mouse retina. Crx expression is restricted to developing and mature photoreceptor cells. CRX bound and transactivated the sequence TAATCC/A, which is found upstream of several photoreceptor-specific genes, including the opsin genes from many species. Overexpression of Crx using a retroviral vector increased the frequency of clones containing exclusively rod photoreceptors and reduced the frequency of clones containing amacrine interneurons and Müller glial cells. In addition, presumptive photoreceptor cells expressing a dominant-negative form of CRX failed to form proper photoreceptor outer segments and terminals. Crx is a novel photoreceptor-specific transcription factor and plays a crucial role in the differentiation of photoreceptor cells

Telescoping Cup Holder

Cup holders are a beloved feature of the modern automobile because they keep your drink stable and close, ensuring that minimal work is needed to grab it. Our mission is to provide a cup holder for everyday use outside of vehicles. Our device will hold drinks of most sizes, and will keep them cool. Motion activation will raise the drink to a convenient height using a telescoping motion, and then lower to a sturdy position that is out of the way. The finished product will minimize the amount of work required to retrieve the drink, and grab some attention as a unique fixture in any living room, tailgate, or man cave

The Effects of Vertical Jump Fatigue and Sprint Fatigue on Total-Body Biomechanics

INTRODUCTION: Motion capture systems (MCS) can be used to assess an individual’s upper-and lower-body motions, both explosive and functional in nature. Advancements in technology and screening protocols are capable of detecting acute biomechanical alterations of the lower-extremities following fatiguing tasks. PURPOSE: This study compared the kinetic and kinematic variables measured by a 3-dimesional video MCS to identify alterations in lower-extremity performance following VJ and sprint fatiguing tasks. METHODS: Eleven healthy, recreationally active women (X ̅±SD; age=20.81.1 yrs., hgt.=172.27.4 cm, wgt.=68.07.2 kg) and eleven men (age=23.02.6 yrs., hgt.=180.34.8 cm, wgt.=80.47.3 kg) volunteered for this investigation, and were screened using the Performance Motion Analysis (PMA) protocol, consisting of 19 motions. These include shoulder ranges of motions (i.e., shoulder abduction and adduction, horizonal abduction and adduction, internal and external rotation, flexion and extension). Also assessed were trunk rotation, bilateral overhead squat, unilateral squats, forward lunges, single leg balance, bilateral counter-movement vertical jump (CMVJ), unilateral CMVJs, concentric-only VJ, multiple unilateral CMVJs, and depth VJ. A three-dimensional markerless MCS (DARI Motion, Scientific Analytics, Lincoln, NE) was used to analyze the kinetic and kinematic data, from which 192 variables were calculated and reported in PMA Scores (i.e. Composite Score, Power Score, Functional Strength Score, Dysfunction Score, Vulnerability Score, and Exercise Readiness Score). Each subject completed one familiarization session, three experimental sessions consisting of three randomized acute fatiguing protocols (i.e. Control Session, Modified jump test, 25-sec Sprint Test). PMA Test, accumulated lactate and heart rate (HR) was collected pre-and post-fatigue tests. Statistical analyses were conducted for the performance measures using the scores [Composite Score, Power Score, Functional Strength Score, Dysfunction Score, Exercise Readiness Score (ERS), and Vulnerability Score] x conditions (VJ, Sprint, CON) x time (pre-test, post-test) x within sex (females, males) repeated measures MANOVA. RESULTS: The MANOVA indicated a three-way interaction (score x condition x time). Follow-up analyses indicated significant differences between pre-and post-tests for the ((X ) ̅± SD for pre-test; post-tests) Composite Score (1556.43±307.8; 1368.00±264.62), Power Score (813.34±242.39; 687.32±164.83), and ERS (18.16±4.75; 16.02±3.54) during the VJ experimental sessions. Significant increases in accumulated lactate and HR were indicated for the post-test during the modified VJ and 25-sec sprint tests. CONCLUSION: The current investigation demonstrated the viability of a MCS test to evaluate changes in performance due to acute fatigue. The investigation determined the MCS was capable of detecting acute lower-body biomechanical changes. The PMA Scores suggested decrements in performance are first observed in the decreases in power production during high velocity movements (i.e. VJs). PRACTICAL APPLICATION: Documentation and tracking of changes in performances will give future insights on how fatigue can be rated and evaluated. Advancements in technology and screening protocols may be capable of predicting increased risk of season ending injuries. This may provide the strength and conditioning professional helpful longitudinal information as an athlete/patient/client progresses through a training program and season

Temporal order of bipolar cell genesis in the neural retina

NEURAL DEVELOPMENT www.neuraldevelopment.com Temporal order of bipolar cell genesis in the neural retina Eric M Morrow et al