Rover Low Gain Antenna Qualification for Deep Space Thermal Environments

A method to qualify the Rover Low Gain Antenna (RLGA) for use during the Mars Science Laboratory (MSL) mission has been devised. The RLGA antenna must survive all ground operations, plus the nominal 670 Martian sol mission that includes the summer and winter seasons of the Mars thermal environment. This qualification effort was performed to verify that the RLGA design, its bonding, and packaging processes are adequate. The qualification test was designed to demonstrate a survival life of three times more than all expected ground testing, plus a nominal 670 Martian sol missions. Baseline RF tests and a visual inspection were performed on the RLGA hardware before the start of the qualification test. Functional intermittent RF tests were performed during thermal chamber breaks over the course of the complete qualification test. For the return loss measurements, the RLGA antenna was moved to a test area. A vector network analyzer was calibrated over the operational frequency range of the antenna. For the RLGA, a simple return loss measurement was performed. A total of 2,010 (3 670 or 3 times mission thermal cycles) thermal cycles was performed. Visual inspection of the RLGA hardware did not show any anomalies due to the thermal cycling. The return loss measurement results of the RLGA antenna after the PQV (Package Qualification and Verification) test did not show any anomalies. The antenna pattern data taken before and after the PQV test at the uplink and downlink frequencies were unchanged. Therefore, the developed design of RLGA is qualified for a long-duration MSL mission

Kalirin Decreases Bone Mass Through Effects in Both Osteoclasts and Osteoblasts

poster abstractBone homeostasis is maintained by the balance between osteoclasts which degrade bone and osteoblasts, which form new bone. When the activity of either of these cells is dysregulated, bone loss can ensue, leading to osteoporosis, a disease characterized by low bone mass and an increase in bone fragility and risk of fracture. The activity of osteoclasts and osteoblasts is regulated by local and systemic factors, as well as by key signaling proteins expressed in these cells. Kalirin is a novel GTP-exchange factor protein that plays a role in signaling pathways leading to cytoskeletal remodeling and dendritic spine formation in neurons, but its function in other cells is unknown. Western blotting and real time PCR confirmed that Kalirin is expressed in osteoclasts and osteoblasts, suggesting it may play a role in regulating bone cell function and bone mass. We used micro-CT to examine the bone phenotype of 14 week old female mice lacking Kalirin in all tissues (Kal-KO). Kal-KO mice exhibited a 40% lower trabecular bone volume in the distal femur compared to wild-type (WT) mice (n=9/group, p<0.05). We next quantified osteoclasts in histological sections by counting multinucleated cells expressing tartrate-resistant acid phosphatase (TRAP), a marker of mature osteoclasts. We found 48% higher osteoclast surface/bone surface in trabecular bone of Kal-KO mice, compared to WT mice (n=6/group, p<0.05). Osteoclast differentiation is controlled by osteoblasts, which secrete receptor activator of NF-kB ligand (RANKL), macrophage colony stimulating factor (MCSF) and osteoprotegerin (OPG), a decoy receptor for RANKL. We examined if Kalirin could regulate osteoclast differentiation in vitro. Osteoclasts were generated from the bone marrow of WT or Kal-KO mice by incubation with RANKL and MCSF for 7 days, and TRAP+ multinucleated cells were counted. Consistent with our in vivo studies, osteoclast number was significantly higher in cultures from Kal-KO mice, compared to WT mice. We next examined if Kalirin altered the ratio of secreted RANKL and OPG secreted by osteoblasts. Osteoblasts were generated from the calvaria of 2 day old neonates and the level of secreted RANKL and OPG in conditioned media was quantified by ELISA. Consistent with increased osteoclast differentiation, we found a higher RANKL/OPG ratio in conditioned media from Kal-KO osteoblasts, compared to WT cells. These data confirm a role for Kalirin in the regulation of trabecular bone mass through effects in both osteoclasts and osteoblasts

Diluted planar ferromagnets: nonlinear excitations on a non-simply connected manifold

We study the behavior of magnetic vortices on a two-dimensional support manifold being not simply connected. It is done by considering the continuum approach of the XY-model on a plane with two disks removed from it. We argue that an effective attractive interaction between the two disks may exist due to the presence of a vortex. The results can be applied to diluted planar ferromagnets with easy-plane anisotropy, where the disks can be seen as nonmagnetic impurities. Simulations are also used to test the predictions of the continuum limit.Comment: 5 pages, 6 figure

The Arabidopsis SR45 splicing factor, a negative regulator of sugar signaling, modulates SNF1-related protein kinase 1 (SnRK1) stability

The deposited article is a post-print version and has been submitted to peer review.This publication hasn't any creative commons license associated.This deposit is composed by the main article, and it hasn't any supplementary materials associated.The ability to sense and respond to sugar signals allows plants to cope with environmental and metabolic changes by adjusting growth and development accordingly. We previously reported that the SR45 splicing factor negatively regulates glucose signaling during early seedling development in Arabidopsis thaliana Here, we show that under glucose-fed conditions, the Arabidopsis sr45-1 loss-of-function mutant contains higher amounts of the energy-sensing SNF1-Related Protein Kinase 1 (SnRK1) despite unaffected SnRK1 transcript levels. In agreement, marker genes for SnRK1 activity are upregulated in sr45-1 plants, and the glucose hypersensitivity of sr45-1 is attenuated by disruption of the SnRK1 gene. Using a high-resolution RT-PCR panel, we found that the sr45-1 mutation broadly targets alternative splicing in vivo, including that of the SR45 pre-mRNA itself. Importantly, the enhanced SnRK1 levels in sr45-1 are suppressed by a proteasome inhibitor, indicating that SR45 promotes targeting of the SnRK1 protein for proteasomal destruction. Finally, we demonstrate that SR45 regulates alternative splicing of the Arabidopsis 5PTase13 gene, which encodes an inositol polyphosphate 5-phosphatase previously shown to interact with and regulate the stability of SnRK1 in vitro, thus providing a mechanistic link between SR45 function and the modulation of degradation of the SnRK1 energy sensor in response to sugars.Fundação para a Ciência e a Tecnologia grants: (PTDC/BIA-PLA/3937/2012, PTDC/BIA-PLA/1084/2014, SFRH/BPD/80073/2011, SFRH/BPD/94796/2013); EMBO Installation Program: (EMBO-Proj.1984); Scottish Government Rural and Environment Science and Analytical Services (RESAS).info:eu-repo/semantics/publishedVersio

Improving the representation of adaptation in climate change impact models

Climate change adaptation is a complex human process, framed by uncertainties and constraints, which is difficult to capture in existing assessment models. Attempts to improve model representations are hampered by a shortage of systematic descriptions of adaptation processes and their relevance to models. This paper reviews the scientific literature to investigate conceptualisations and models of climate change adaptation, and the ways in which representation of adaptation in models can be improved. The review shows that real-world adaptive responses can be differentiated along a number of dimensions including intent or purpose, timescale, spatial scale, beneficiaries and providers, type of action, and sector. However, models of climate change consequences for land use and water management currently provide poor coverage of these dimensions, instead modelling adaptation in an artificial and subjective manner. While different modelling approaches do capture distinct aspects of the adaptive process, they have done so in relative isolation, without producing improved unified representations. Furthermore, adaptation is often assumed to be objective, effective and consistent through time, with only a minority of models taking account of the human decisions underpinning the choice of adaptation measures (14%), the triggers that motivate actions (38%) or the time-lags and constraints that may limit their uptake and effectiveness (14%). No models included adaptation to take advantage of beneficial opportunities of climate change. Based on these insights, transferable recommendations are made on directions for future model development that may enhance realism within models, while also advancing our understanding of the processes and effectiveness of adaptation to a changing climate

The PTF Orion Project: a Possible Planet Transiting a T-Tauri Star

We report observations of a possible young transiting planet orbiting a previously known weak-lined T-Tauri star in the 7-10 Myr old Orion-OB1a/25-Ori region. The candidate was found as part of the Palomar Transient Factory (PTF) Orion project. It has a photometric transit period of 0.448413 +- 0.000040 days, and appears in both 2009 and 2010 PTF data. Follow-up low-precision radial velocity (RV) observations and adaptive optics imaging suggest that the star is not an eclipsing binary, and that it is unlikely that a background source is blended with the target and mimicking the observed transit. RV observations with the Hobby-Eberly and Keck telescopes yield an RV that has the same period as the photometric event, but is offset in phase from the transit center by approximately -0.22 periods. The amplitude (half range) of the RV variations is 2.4 km/s and is comparable with the expected RV amplitude that stellar spots could induce. The RV curve is likely dominated by stellar spot modulation and provides an upper limit to the projected companion mass of M_p sin i_orb < 4.8 +- 1.2 M_Jup; when combined with the orbital inclination, i orb, of the candidate planet from modeling of the transit light curve, we find an upper limit on the mass of the planetary candidate of M_p < 5.5 +- 1.4 M_Jup. This limit implies that the planet is orbiting close to, if not inside, its Roche limiting orbital radius, so that it may be undergoing active mass loss and evaporation.Comment: Corrected typos, minor clarifications; minor updates/corrections to affiliations and bibliography. 35 pages, 10 figures, 3 tables. Accepted to Ap

The Atacama Cosmology Telescope: A Measurement of the Cosmic Microwave Background Power Spectrum at 148 and 218 GHz from the 2008 Southern Survey

We present measurements of the cosmic microwave background (CMB) power spectrum made by the Atacama Cosmology Telescope at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels. Our results clearly show the second through the seventh acoustic peaks in the CMB power spectrum. The measurements of these higher-order peaks provide an additional test of the {\Lambda}CDM cosmological model. At l > 3000, we detect power in excess of the primary anisotropy spectrum of the CMB. At lower multipoles 500 < l < 3000, we find evidence for gravitational lensing of the CMB in the power spectrum at the 2.8{\sigma} level. We also detect a low level of Galactic dust in our maps, which demonstrates that we can recover known faint, diffuse signals.Comment: 19 pages, 13 figures. Submitted to ApJ. This paper is a companion to Hajian et al. (2010) and Dunkley et al. (2010

Advanced EFL learners' beliefs about language learning and teaching: a comparison between grammar, pronunciation, and vocabulary

This paper reports on the results of a study exploring learners’ beliefs on the learning and teaching of English grammar, pronunciation and vocabulary at tertiary level. While the importance of learners’ beliefs on the acquisition process is generally recognized, few studies have focussed on and compared learners’ views on different components of the language system. A questionnaire containing semantic scale and Likert scale items probing learners’ views on grammar, pronunciation and vocabulary was designed and completed by 117 native speakers of Dutch in Flanders, who were studying English at university. The analysis of the responses revealed that (i) vocabulary was considered to be different from grammar and pronunciation, both in the extent to which an incorrect use could lead to communication breakdown and with respect to the learners’ language learning strategies, (ii) learners believed in the feasibility of achieving a native-like proficiency in all three components, and (iii) in-class grammar, pronunciation and vocabulary exercises were considered to be useful, even at tertiary level. The results are discussed in light of pedagogical approaches to language teaching