10,628 research outputs found
Measures Matter: Scales for Adaptation, Cultural Distance, and Acculturation Orientation Revisited
Building upon existing measures, four new brief acculturation scales are presented, measuring sociocultural adaptation, psychological adaptation, perceived cultural distance, and acculturation orientation. Following good scale reliability in initial samples, the English scales were translated into nine different languages (Chinese, French, German, Italian, Japanese, Portuguese, Spanish, Thai, and Turkish). The translated scales were administered to a large sample of sojourners (N = 1,929), demonstrating good reliability and adequate structural equivalence across languages. In line with existing theory, sociocultural adaptation and psychological adaptation were positively correlated, and showed a negative association with perceived cultural distance. General measures of well-being were correlated with adaptation and distance, with better adaptation relating to higher well-being, and more distance relating to lower well-being. Acculturation orientation toward the home and host culture were measured separately and a weak negative correlation was found between the two, supporting their independence. Arguing against dichotomization, these subscales were analyzed as continuous variables. Regression analysis showed sojourners to be better adapted, if they were oriented more toward the host culture and less toward the home culture. These new scales are proposed as alternatives to existing measures
Profile of the U 5f magnetization in U/Fe multilayers
Recent calculations, concerning the magnetism of uranium in the U/Fe
multilayer system have described the spatial dependence of the 5f polarization
that might be expected. We have used the x-ray resonant magnetic reflectivity
technique to obtain the profile of the induced uranium magnetic moment for
selected U/Fe multilayer samples. This study extends the use of x-ray magnetic
scattering for induced moment systems to the 5f actinide metals. The spatial
dependence of the U magnetization shows that the predominant fraction of the
polarization is present at the interfacial boundaries, decaying rapidly towards
the center of the uranium layer, in good agreement with predictions.Comment: 7 pages, 6 figure
Common Genetic Variants Found in HLA and KIR Immune Genes in Autism Spectrum Disorder
The “common variant—common disease” hypothesis was proposed to explain diseases with strong inheritance. This model suggests that a genetic disease is the result of the combination of several common genetic variants. Common genetic variants are described as a 5% frequency differential between diseased vs. matched control populations. This theory was recently supported by an epidemiology paper stating that about 50% of genetic risk for autism resides in common variants. However, rare variants, rather than common variants, have been found in numerous genome wide genetic studies and many have concluded that the “common variant—common disease” hypothesis is incorrect. One interpretation is that rare variants are major contributors to genetic diseases and autism involves the interaction of many rare variants, especially in the brain. It is obvious there is much yet to be learned about autism genetics. Evidence has been mounting over the years indicating immune involvement in autism, particularly the HLA genes on chromosome 6 and KIR genes on chromosome 19. These two large multigene complexes have important immune functions and have been shown to interact to eliminate unwanted virally infected and malignant cells. HLA proteins have important functions in antigen presentation in adaptive immunity and specific epitopes on HLA class I proteins act as cognate ligands for KIR receptors in innate immunity. Data suggests that HLA alleles and KIR activating genes/haplotypes are common variants in different autism populations. For example, class I allele (HLA-A2 and HLA-G 14 bp-indel) frequencies are significantly increased by more than 5% over control populations (Table 2). The HLA-DR4 Class II and shared epitope frequencies are significantly above the control populations (Table 2). Three activating KIR genes: 3DS1, 2DS1, and 2DS2 have increased frequencies of 15, 22, and 14% in autism populations, respectively. There is a 6% increase in total activating KIR genes in autism over control subjects. And, more importantly there is a 12% increase in activating KIR genes and their cognate HLA alleles over control populations (Torres et al., 2012a). These data suggest the interaction of HLA ligand/KIR receptor pairs encoded on two different chromosomes is more significant as a ligand/receptor complex than separately in autism
Control-Flow Integrity for Real-Time Embedded Systems
Attacks on real-time embedded systems can endanger lives and critical infrastructure. Despite this, techniques for securing embedded systems software have not been widely studied. Many existing security techniques for general-purpose computers rely on assumptions that do not hold in the embedded case. This paper focuses on one such technique, control-flow integrity (CFI), that has been vetted as an effective countermeasure against control-flow hijacking attacks on general-purpose computing systems. Without the process isolation and fine-grained memory protections provided by a general-purpose computer with a rich operating system, CFI cannot provide any security guarantees. This work proposes RECFISH, a system for providing CFI guarantees on ARM Cortex-R devices running minimal real-time operating systems. We provide techniques for protecting runtime structures, isolating processes, and instrumenting compiled ARM binaries with CFI protection. We empirically evaluate RECFISH and its performance implications for real-time systems. Our results suggest RECFISH can be directly applied to binaries without compromising real-time performance; in a test of over six million realistic task systems running FreeRTOS, 85% were still schedulable after adding RECFISH
Quad-Chip Double-Balanced Frequency Tripler
Solid-state frequency multipliers are used to produce tunable broadband sources at millimeter and submillimeter wavelengths. The maximum power produced by a single chip is limited by the electrical breakdown of the semiconductor and by the thermal management properties of the chip. The solution is to split the drive power to a frequency tripler using waveguides to divide the power among four chips, then recombine the output power from the four chips back into a single waveguide. To achieve this, a waveguide branchline quadrature hybrid coupler splits a 100-GHz input signal into two paths with a 90 relative phase shift. These two paths are split again by a pair of waveguide Y-junctions. The signals from the four outputs of the Y-junctions are tripled in frequency using balanced Schottky diode frequency triplers before being recombined with another pair of Y-junctions. A final waveguide branchline quadrature hybrid coupler completes the combination. Using four chips instead of one enables using four-times higher power input, and produces a nearly four-fold power output as compared to using a single chip. The phase shifts introduced by the quadrature hybrid couplers provide isolation for the input and output waveguides, effectively eliminating standing waves between it and surrounding components. This is accomplished without introducing the high losses and expense of ferrite isolators. A practical use of this technology is to drive local oscillators as was demonstrated around 300 GHz for a heterodyne spectrometer operating in the 2-3-THz band. Heterodyne spectroscopy in this frequency band is especially valuable for astrophysics due to the presence of a very large number of molecular spectral lines. Besides high-resolution radar and spectrographic screening applications, this technology could also be useful for laboratory spectroscopy
The Role of Galactic Winds on Molecular Gas Emission from Galaxy Mergers
We assess the impact of starburst and AGN feedback-driven winds on the CO
emission from galaxy mergers, and, in particular, search for signatures of
these winds in the simulated CO morphologies and emission line profiles. We do
so by combining a 3D non-LTE molecular line radiative transfer code with
smoothed particle hydrodynamics (SPH) simulations of galaxy mergers that
include prescriptions for star formation, black hole growth, a multiphase
interstellar medium (ISM), and the winds associated with star formation and
black hole growth. Our main results are: (1) Galactic winds can drive outflows
of masses ~10^8-10^9 Msun which may be imaged via CO emission line mapping. (2)
AGN feedback-driven winds are able to drive imageable CO outflows for longer
periods of time than starburst-driven winds owing to the greater amount of
energy imparted to the ISM by AGN feedback compared to star formation. (3)
Galactic winds can control the spatial extent of the CO emission in post-merger
galaxies, and may serve as a physical motivation for the sub-kiloparsec scale
CO emission radii observed in local advanced mergers. (4) Secondary emission
peaks at velocities greater than the circular velocity are seen in the CO
emission lines in all models. In models with winds, these high velocity peaks
are seen to preferentially correspond to outflowing gas entrained in winds,
which is not the case in the model without winds. The high velocity peaks seen
in models without winds are typically confined to velocity offsets (from the
systemic) < 1.7 times the circular velocity, whereas the models with AGN
feedback-driven winds can drive high velocity peaks to ~2.5 times the circular
velocity.Comment: Accepted by ApJ; Minor revisions; Resolution tests include
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