Prediction of three sigma maximum dispersed density for aerospace applications

Free molecular heating (FMH) is caused by the transfer of energy during collisions between the upper atmosphere molecules and a space vehicle. The dispersed free molecular heating on a surface is an important constraint for space vehicle thermal analyses since it can be a significant source of heating. To reduce FMH to a spacecraft, the parking orbit is often designed to a higher altitude at the expense of payload capability. Dispersed FMH is a function of both space vehicle velocity and atmospheric density, however, the space vehicle velocity variations are insignificant when compared to the atmospheric density variations. The density of the upper atmosphere molecules is a function of altitude, but also varies with other environmental factors, such as solar activity, geomagnetic activity, location, and time. A method has been developed to predict three sigma maximum dispersed density for up to 15 years into the future. This method uses a state-of-the-art atmospheric density code, MSIS 86, along with 50 years of solar data, NASA and NOAA solar activity predictions for the next 15 years, and an Aerospace Corporation correlation to account for density code inaccuracies to generate dispersed maximum density ratios denoted as 'K-factors'. The calculated K-factors can be used on a mission unique basis to calculate dispersed density, and hence dispersed free molecular heating rates. These more accurate K-factors can allow lower parking orbit altitudes, resulting in increased payload capability

Enantiopure water-soluble [Fe4L6] cages: host-guest chemistry and catalytic activity.

This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/anie.20130213

A Triphasic Sorting System: Coordination Cages in Ionic Liquids.

Host-guest chemistry is usually carried out in either water or organic solvents. To investigate the utility of alternative solvents, three different coordination cages were dissolved in neat ionic liquids. By using (19) F NMR spectroscopy to monitor the presence of free and bound guest molecules, all three cages were demonstrated to be stable and capable of encapsulating guests in ionic solution. Different cages were found to preferentially dissolve in different phases, allowing for the design of a triphasic sorting system. Within this system, three coordination cages, namely Fe4 L6 2, Fe8 L12 3, and Fe4 L4 4, each segregated into a distinct layer. Upon the addition of a mixture of three different guests, each cage (in each separate layer) selectively bound its preferred guest.This work was supported by the European Research Council (259352). We also thank the Cambridge Chemistry NMR service for experimental assistance.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/anie.20150577

Controllability Modulates the Anticipatory Response in the Human Ventromedial Prefrontal Cortex

Research has consistently shown that control is critical to psychological functioning, with perceived lack of control considered to play a crucial role in the manifestation of symptoms in psychiatric disorders. In a model of behavioral control based on non-human animal work, Maier et al. (2006) posited that the presence of control activates areas of the ventromedial prefrontal cortex (vmPFC), which in turn inhibit the normative stress response in the dorsal raphe nucleus and amygdala. To test Maier’s model in humans, we investigated the effects of control over potent aversive stimuli by presenting video clips of snakes to 21 snake phobics who were otherwise healthy with no comorbid psychopathologies. Based on prior research documenting that disrupted neural processing during the anticipation of adverse events can be influenced by different forms of cognitive processing such as perceptions of control, analyses focused on the anticipatory activity preceding the videos. We found that phobics exhibited greater vmPFC activity during the anticipation of snake videos when they had control over whether the videos were presented as compared to when they had no control over the presentation of the videos. In addition, observed functional connectivity between the vmPFC and the amygdala is consistent with previous work documenting vmPFC inhibition of the amygdala. Our results provide evidence to support the extension of Maier’s model of behavioral control to include anticipatory function in humans

Mudbricks, Construction Methods, and Stratigraphic Analysis : A Case Study at Tell Timai (ancient Thmuis) in the Egyptian Delta

The Graeco-Roman site of Tell Timai (ancient Thmuis) in Lower Egypt is among the largest urban tells in the Nile Delta, boasting substantial amounts of preserved earthen architecture. Although earthen architecture made up the vast majority of public and domestic structures in ancient Egypt, it still does not receive the same analytical attention from archaeologists as other categories of evidence. This paper presents a case study for the archaeological investigation of the earthen architecture at Tell Timai. The goal was to develop a methodology that can be implemented in the field by excavators with little geoarchaeological training and limited laboratory access in order to generate useful data for determining building stratigraphy and studying construction processes. Through the close examination and sampling of three buildings of different periods and scales, we tested a new field methodology combining geoarchaeological techniques and mensiochronology. The results provide information useful for stratigraphy and phasing as well as for identifying specific patterns of mudbrick manufacturing, production, and construction during the Graeco-Roman period at Tell Timai.Peer reviewe

B cell hyperresponsiveness and expansion of mature follicular B cells but not of marginal zone B cells in NFATc2/c3 double-deficient mice

Marginal zone (MZ) B cells and peritoneal B-I cells provide a first defense system of thymus-independent Ab responses against foreign pathogens and therefore share a number of functional properties. Recently, development of B-1a cells was shown to be controlled by the transcription factor NFATc1. We show here that mice deficient for NFATc2 and c3 display a distinct lower representation of MZ B cells, which is correlated with a reduced capturing of trinitrophenyl-Ficoll. In contrast, mature follicular B cells from NFATc2/c3(-/-) mice are strongly increased in number. NFATc2/c3-/- B cells exhibit a marked increase in BCR-induced intracellular Ca(2+) mobilization and proliferation. However, trinitrophenyl-Ficoll-specific IgM and IgG3 responses of NFATc2/c3-deficient mice are intact, and chimeric mice reconstituted with NFATc2/3-deficient B cells show a normal number of MZ B cells and normal BCR responses. These observations suggest that the strongly elevated Th2 cytokine milieu in NFATc2/c3-deficient mice leads to a hyperactivation of mature, follicular B cells, whereas MZ B cells are less responsive to these signals

CD22 regulates early B cell development in BOB.1/OBF.1-deficient mice

BOB.1/OBF1 (also called OCA-B), a B lymphocyte-specific transcriptional coactivator, is recruited to octamer-containing promoters by interacting with the Oct-1 or Oct-2 proteins. BOB.1/OBF.1-deficient mice show impaired secondary immunoglobulin isotype secretion and complete absence of germinal centers. Furthermore, numbers of splenic B cells are reduced due to a developmental block at the transitional B cell stage in the bone marrow. We found that surface expression of CD22 is selectively increased on B lineage cells in the bone marrow of BOB.1/OBF.1-deficient mice. CD22 is known as a negative regulator of B cell receptor signaling. We therefore investigated whether defects in B cell development in the BOB.1/OBF1-deficient mice might be due to CD22 up-regulation. Mice were generated lacking both genes. In BOB.1/OBF.1 xCD22 double-deficient mice, numbers of transitional B cells in the bone marrow were normal. Consequently, double-deficient mice also had normal B to T cell ratios in the spleen. We show that BOB.1/OBF.1(-/-) B cells were incapable to induce BCR-triggered Ca2+ mobilization. This Ca2+-signalling defect was restored in BOBA/ OBF1 xCD22 double-deficient B cells. Nevertheless, double-deficient animals were unable to mount humoral immune responses and to form germinal centers. Finally, we demonstrate that CD22(-/-) splenic B cells proliferate independently of BOB.1/OBF1 upon stimulation with LPS. These studies suggest that the B cell differentiation defect observed in BOB.1/OBF.1(-/-) mice is BCR-signal dependent. However, the impairment in germinal center formation is caused by a different mechanism

The Impact of Heat Waves on Mortality in Seven Major Cities in Korea

Background: Understanding the health impacts of heat waves is important, especially given anticipated increases in the frequency, duration, and intensity of heat waves due to climate change

Neuro-evolution Methods for Designing Emergent Specialization

This research applies the Collective Specialization Neuro-Evolution (CONE) method to the problem of evolving neural controllers in a simulated multi-robot system. The multi-robot system consists of multiple pursuer (predator) robots, and a single evader (prey) robot. The CONE method is designed to facilitate behavioral specialization in order to increase task performance in collective behavior solutions. Pursuit-Evasion is a task that benefits from behavioral specialization. The performance of prey-capture strategies derived by the CONE method, are compared to those derived by the Enforced Sub-Populations (ESP) method. Results indicate that the CONE method effectively facilitates behavioral specialization in the team of pursuer robots. This specialization aids in the derivation of robust prey-capture strategies. Comparatively, ESP was found to be not as appropriate for facilitating behavioral specialization and effective prey-capture behaviors

Prioritising search effort to locate previously unknown populations of endangered marine reptiles

Strategies aimed to conserve and manage rare species are often hindered by the lack of data needed for their effective design. Incomplete and inaccurate data on habitat associations and current species distributions pose a barrier to effective conservation and management for several species of endemic sea snakes in Western Australia that are thought to be in decline. Here we used a correlative modelling approach to understand habitat associations and identify suitable habitats for five of these species (Aipysurus apraefrontalis, A. foliosquama, A. fuscus, A. l. pooleorum and A. tenuis). We modelled species-specific habitat suitability across 804,244 km(2) of coastal waters along the North-west Shelf of Western Australia, to prioritise future survey regions to locate unknown populations of these rare species. Model projections were also used to quantify the effectiveness of current spatial management strategies (Marine Protected Areas) in conserving important habitats for these species. Species-specific models matched well with the records on which they were trained, and identified additional regions of suitability without records. Subsequent field validation of the model projections uncovered a previously unknown locality for A. fuscus within the mid-shelf shoal region, outside its currently recognised global range. Defining accurate geographic distributions for rare species is a vital first step in defining more robust extent of species occurrence and range overlap with threatening processes