22,758 research outputs found
Adhesive coating eliminated in new honeycomb-core fabrication process
Technique eliminates use of silicone-based adhesive material as bonding medium. Adhesive requires precise time-temperature cure. Prepreg resin is used as bonding medium, and each layer is laminated together to form honeycomb billet. Process can be used in any application where nonmetallic honeycomb core is being fabricated
Isotope Ratio Monitoring Gas Chromatography Mass Spectrometry (IRM-GCMS)
On Earth, the C-13 content of organic compounds is depleted by roughly 13 to 23 permil from atmospheric carbon dioxide. This difference is largely due to isotope effects associated with the fixation of inorganic carbon by photosynthetic organisms. If life once existed on Mars, then it is reasonable to expect to observe a similar fractionation. Although the strongly oxidizing conditions on the surface of Mars make preservation of ancient organic material unlikely, carbon-isotope evidence for the existence of life on Mars may still be preserved. Carbon depleted in C-13 could be preserved either in organic compounds within buried sediments, or in carbonate minerals produced by the oxidation of organic material. A technique is introduced for rapid and precise measurement of the C-13 contents of individual organic compounds. A gas chromatograph is coupled to an isotope-ratio mass spectrometer through a combustion interface, enabling on-line isotopic analysis of isolated compounds. The isotope ratios are determined by integration of ion currents over the course of each chromatographic peak. Software incorporates automatic peak determination, corrections for background, and deconvolution of overlapped peaks. Overall performance of the instrument was evaluated by the analysis of a mixture of high purity n-alkanes of know isotopic composition. Isotopic values measured via IRM-GCMS averaged withing 0.55 permil of their conventionally measured values
Network recovery from massive failures under uncertain knowledge of damages
This paper addresses progressive network recovery under uncertain knowledge of damages. We formulate the problem as a mixed integer linear programming (MILP), and show that it is NP-Hard. We propose an iterative stochastic recovery algorithm (ISR) to recover the network in a progressive manner to satisfy the critical services. At each optimization step, we make a decision to repair a part of the network and gather more information iteratively, until critical services are completely restored. Three different algorithms are used to find a feasible set and determine which node to repair, namely, 1) an iterative shortest path algorithm (ISR-SRT), 2) an approximate branch and bound (ISR-BB) and 3) an iterative multi-commodity LP relaxation (ISR-MULT). Further, we have modified the state-of-the-Art iterative split and prune (ISP) algorithm to incorporate the uncertain failures. Our results show that ISR-BB and ISR- MULT outperform the state-of-the-Art 'progressive ISP' algorithm while we can configure our choice of trade-off between the execution time, number of repairs (cost) and the demand loss. We show that our recovery algorithm, on average, can reduce the total number of repairs by a factor of about 3 with respect to ISP, while satisfying all critical deman
Targeting protein–protein interactions within the cyclic AMP signaling system as a therapeutic strategy for cardiovascular disease
The cAMP signaling system can trigger precise physiological cellular responses that depend on the fidelity of many protein–protein interactions, which act to bring together signaling intermediates at defined locations within cells. In the heart, cAMP participates in the fine control of excitation–contraction coupling, hence, any disregulation of this signaling cascade can lead to cardiac disease. Due to the ubiquitous nature of the cAMP pathway, general inhibitors of cAMP signaling proteins such as PKA, EPAC and PDEs would act non-specifically and universally, increasing the likelihood of serious ‘off target’ effects. Recent advances in the discovery of peptides and small molecules that disrupt the protein–protein interactions that underpin cellular targeting of cAMP signaling proteins are described and discussed
Spin freezing and dynamics in Ca_{3}Co_{2-x}Mn_{x}O_{6} (x ~ 0.95) investigated with implanted muons: disorder in the anisotropic next-nearest neighbor Ising model
We present a muon-spin relaxation investigation of the Ising chain magnet
Ca_{3}Co_{2-x}Mn_{x}O_{6} (x~0.95). We find dynamic spin fluctuations
persisting down to the lowest measured temperature of 1.6 K. The previously
observed transition at around T ~18 K is interpreted as a subtle change in
dynamics for a minority of the spins coupling to the muon that we interpret as
spins locking into clusters. The dynamics of this fraction of spins freeze
below a temperature T_{SF}~8 K, while a majority of spins continue to
fluctuate. An explanation of the low temperature behavior is suggested in terms
of the predictions of the anisotropic next-nearest-neighbor Ising model.Comment: 4 pages, 2 figure
Summary of a Crew-Centered Flight Deck Design Philosophy for High-Speed Civil Transport (HSCT) Aircraft
Past flight deck design practices used within the U.S. commercial transport aircraft industry have been highly successful in producing safe and efficient aircraft. However, recent advances in automation have changed the way pilots operate aircraft, and these changes make it necessary to reconsider overall flight deck design. Automated systems have become more complex and numerous, and often their inner functioning is partially or fully opaque to the flight crew. Recent accidents and incidents involving autoflight system mode awareness Dornheim, 1995) are an example. This increase in complexity raises pilot concerns about the trustworthiness of automation, and makes it difficult for the crew to be aware of all the intricacies of operation that may impact safe flight. While pilots remain ultimately responsible for mission success, performance of flight deck tasks has been more widely distributed across human and automated resources. Advances in sensor and data integration technologies now make far more information available than may be prudent to present to the flight crew
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Bump start needed: linking guidelines, policy and practice in promoting physical activity during and beyond pregnancy
First paragraph: There is compelling evidence that regular physical activity (PA) during pregnancy benefits both mother and baby.1 2 Notably, physical and psychological benefits are evident in the literature, such as marked reductions in the development of gestational diabetes and hypertensive disorders, alongside improvements in depressive symptoms and cardiorespiratory fitness.1 2 The evidence base has been reflected by recent policy initiatives, for example, in 2017 (relaunched in 2019), the UK‘s chief medical officers (CMOs) published PA guidelines for pregnant women, which made substantial strides in unifying and translating the evidence into recommendations.1 The CMO guidelines are aimed at supporting health professionals to provide consistent, evidence-based PA messages to women throughout pregnancy.1 Recently, the Chartered Institute for the Management of Sport and Physical Activity have updated their professional standards for working with antenatal and postnatal clients to align with these CMO guidelines.3 However, not all women have access to professionals with this level of expertise and training, potentially limiting the impact of the CMO guidelines
Muon-spin relaxation and heat capacity measurements on the magnetoelectric and multiferroic pyroxenes LiFeSi2O6 and NaFeSi2O6
The results of muon-spin relaxation and heat capacity measurements on two
pyroxene compounds LiFeSi2O6 and NaFeSi2O6 demonstrate that despite their
underlying structural similarity the magnetic ordering is considerably
different. In LiFeSi2O6 a single muon precession frequency is observed below
TN, consistent with a single peak at TN in the heat capacity and a commensurate
magnetic structure. In applied magnetic fields the heat capacity peak splits in
two. In contrast, for natural NaFeSi2O6, where multiferroicity has been
observed in zero-magnetic-field, a rapid Gaussian depolarization is observed
showing that the magnetic structure is more complex. Synthetic NaFeSi2O6 shows
a single muon precession frequency but with a far larger damping rate than in
the lithium compound. Heat capacity measurements reproduce the phase diagrams
previously derived from other techniques and demonstrate that the magnetic
entropy is mostly associated with the build up of correlations in the
quasi-one-dimensional Fe3+ chains
Toward the Evidence of the Accretion Disk Emission in the Symbiotic Star RR Tel
In this paper, we argue that in the symbiotic star RR Tel the existence of an
accretion disk around the hot companion is strongly implied by the
characteristic features exhibited by the Raman-scattered O VI lines around 6830
\AA and 7088 \AA. High degrees of polarization and double-peaked profiles in
the Raman-scattered lines and single-peak profiles for other emission lines are
interpreted as line-of-sight effects, where the H I scatterers near the giant
see an incident double-peaked profile and an observer with a low inclination
sees single-peak profiles. It is predicted that different mass concentrations
around the accretion disk formed by a dusty wind may lead to the disparate
ratios of the blue peak strength to the red counterpart observed in the 6830
and 7088 features. We discuss the evolutionary links between symbiotic stars
and bipolar protoplanetary nebulae and conclude that the Raman scattering
processes may play an important role in investigation of the physical
properties of these objects.Comment: 11 pages, 3 figures, accepted for publication in the ApJ Letter
Psychological Flexibility, ACT, and Organizational Behavior
This paper offers organizational behavior management (OBM) a behavior analytically consistent way to expand its analysis of, and methods for changing, organizational behavior. It shows how Relational Frame Theory (RFT) suggests that common, problematic, psychological processes emerge from language itself, and they produce psychological inflexibility. Research suggests that an applied extension of RFT, Acceptance and Commitment Therapy, has led to new interventions that increase psychological flexibility and, thereby enhance, organizational behavior and health
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