345 research outputs found

    STRATEGIES FOR CONTROL OF END-USER COMPUTING: IMPACTS ON END USERS

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    The prevalence of end-user computing has resulted in a need for more effective methods of controlling such computing activities. The present experiment examined the impact of two potential control strategies, behavior-based and outcome-based control, on end-user affective reactions. Results indicated that subjects in the behavior-based control condition reported greater levels of stress, less self-determination, and less process satisfaction than the outcome control group. Further analysis suggested that the detrimental effect of behavior-based control on process satisfaction could be explained through the mediating effect of stress. Implications of the results for the design of effective end-user control strategies are discussed

    Opened and Closed Doors: An Inside Look at How the Internet Changed Middle East Policy

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    From the mainstream media to citizen journalism, and from politicians to activist groups, the rise of social media and the new Internet age has changed the dynamics of global diplomacy, international decision-making and large-scale movements. The Internet age has altered how individuals interpret foreign relations, mobilize movements and influence policy decisions. In the Middle East especially, social media users have demonstrated the power to propel uprisings on authoritarian regimes, stimulate diplomacy and impact relationships between nations. In three chapters, this thesis explores how the U.S.-Israel relationship, the Arab Spring and the Iran nuclear deal were all impacted by the rise of the digital age. Specifically, this thesis explores how communications technology has changed over time, how foreign policy is shaped, how international movements rise, how countries’ reputations are formed and how the Internet can ultimately impact the outcome of major world decisions. After examining several case studies, this thesis concludes that the Internet Age has changed how the world receives information. Moreover, the proliferation of social media has provided individuals with more access to news with just a click of a button. Politicians, journalists and activists now have the ability to communicate directly to the public through their 21st Century technology. In conclusion, this thesis is a snapshot of time regarding how the Internet permanently transformed how the way the international community obtains information

    Distress Levels among Parents of Active Duty Soldiers during Wartime

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    Objective: Military service is a highly stressful period both for the soldiers serving and for their parents. Surprisingly, parents’ experience has been mostly ignored in the research. This study’s goal is to shed light on the experience and distress levels of parents of active duty combat soldiers during Operation Protective Edge, a military operation carried out by the Israel Defense Forces during July and August of 2014.Methods: During the advanced stages of the operation, 69 parents of Israeli male combat soldiers (55 mothers and 14 fathers) completed an online survey measuring symptoms of Posttraumatic Stress Disorder (PTSD-Checklist-5) and distress (Brief Symptom Inventory-18). Participants were recruited using a convenience sample, by posting ads on the public Facebook pages of the researchers and of the groups dedicated to parents of Israeli soldiers.Results: Parents’ depression and anxiety symptom levels were higher than depression and anxiety symptom levels of the adult community norms in Israel. General distress rates of parents were similar to those presented by adults in southern Israel who were exposed for 7 years to the ongoing threat of daily rocket fire from Gaza, and higher than rates of a non-threatened Israeli population. Finally, 20.2% of the parents presented PTSD-like symptoms, a higher percentage than the probable PTSD diagnosis rates that were found in the general population in Israel during previous terror waves.Conclusion: This study provides preliminary evidence of soldiers’ parents’ distress and indicates the need for a better understanding of the impact of military service on soldiers’ parents

    On the Emergent Spectra of Hot Protoplanet Collision Afterglows

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    We explore the appearance of terrestrial planets in formation by studying the emergent spectra of hot molten protoplanets during their collisional formation. While such collisions are rare, the surfaces of these bodies may remain hot at temperatures of 1000-3000 K for up to millions of years during the epoch of their formation. These object are luminous enough in the thermal infrared to be observable with current and next generation optical/IR telescopes, provided that the atmosphere of the forming planet permits astronomers to observe brightness temperatures approaching that of the molten surface. Detectability of a collisional afterglow depends on properties of the planet's atmosphere -- primarily on the mass of the atmosphere. A planet with a thin atmosphere is more readily detected, because there is little atmosphere to obscure the hot surface. Paradoxically, a more massive atmosphere prevents one from easily seeing the hot surface, but also keeps the planet hot for a longer time. In terms of planetary mass, more massive planets are also easier to detect than smaller ones because of their larger emitting surface areas. We present preliminary calculations assuming a range of protoplanet masses (1-10 M_\earth), surface pressures (1-1000 bar), and atmospheric compositions, for molten planets with surface temperatures ranging from 1000 to 1800 K, in order to explore the diversity of emergent spectra that are detectable. While current 8- to 10-m class ground-based telescopes may detect hot protoplanets at wide orbital separations beyond 30 AU (if they exist), we will likely have to wait for next-generation extremely large telescopes or improved diffraction suppression techniques to find terrestrial planets in formation within several AU of their host stars.Comment: 28 pages, 6 figures, ApJ manuscript format, accepted into the Ap

    Formation and Structure of Low Density Exo-Neptunes

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    Kepler has found hundreds of Neptune-size (2-6 R_Earth) planet candidates within 0.5 AU of their stars. The nature of the vast majority of these planets is not known because their masses have not been measured. Using theoretical models of planet formation, evolution and structure, we explore the range of minimum plausible masses for low-density exo-Neptunes. We focus on highly irradiated planets with T_eq>=500K. We consider two separate formation pathways for low-mass planets with voluminous atmospheres of light gases: core nucleated accretion and outgassing of hydrogen from dissociated ices. We show that Neptune-size planets at T_eq=500K with masses as small as a few times that of Earth can plausibly be formed core nucleated accretion coupled with subsequent inward migration. We also derive a limiting low-density mass-radius relation for rocky planets with outgassed hydrogen envelopes but no surface water. Rocky planets with outgassed hydrogen envelopes typically have computed radii well below 3 R_Earth. For both planets with H/He envelopes from core nucleated accretion and planets with outgassed hydrogen envelopes, we employ planet interior models to map the range of planet mass--envelope mass--equilibrium temperature parameter space that is consistent with Neptune-size planet radii. Atmospheric mass loss mediates which corners of this parameter space are populated by actual planets and ultimately governs the minimum plausible mass at a specified transit radius. We find that Kepler's 2-6 R_Earth planet candidates at T_eq=500--1000K could potentially have masses less than ~4 M_Earth. Although our quantitative results depend on several assumptions, our qualitative finding that warm Neptune-size planets can have masses substantially smaller than those given by interpolating the masses and radii of planets within our Solar System is robust.Comment: 17 pages, 9 figures, accepted for publication in Ap

    Autistic College Students and COVID-19: Anxiety, Support Needs and Responses by Specialized Programs

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    Providing resources and support to college students during the COVID-19 global pandemic has produced unique challenges for all students, particularly those with autism. In March 2020, halfway through the spring term, the COVID-19 global pandemic forced most institutions of higher education across the country to move all instruction and support to an online, remote format, including those for students with autism. Colleges and autism support programs are now grappling with how to effectively support students amid a global pandemic. Yet there is little information available about how students’ needs have changed with this new environment. In this exploratory study, 76 college students with autism from across the country answered a series of questions (both Likert scale and open-ended) about their anxieties related to COVID-19 and attending college. The data were analyzed using descriptive statistics and thematic analysis. Results revealed that students are most anxious about getting sick or spreading COVID-19 to others and least anxious about wearing masks and needing to socially distance. This paper also profiles the adjustments made to several college autism support programs (led by the authors) in order to accommodate the changes to college campuses and the impact on student needs. The survey results and recent experiences across programs will inform recommendations for colleges as they build toward more inclusive, supportive campus environments and respond to crises like the pandemic

    Studying the atmosphere of the exoplanet HAT-P-7b via secondary eclipse measurements with EPOXI, Spitzer and Kepler

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    The highly irradiated transiting exoplanet, HAT-P-7b, currently provides one of the best opportunities for studying planetary emission in the optical and infrared wavelengths. We observe six near-consecutive secondary eclipses of HAT-P-7b at optical wavelengths with the EPOXI spacecraft. We place an upper limit on the relative eclipse depth of 0.055% (95% confidence). We also analyze Spitzer observations of the same target in the infrared, obtaining secondary eclipse depths of 0.098+/-0.017%, 0.159+/-0.022%, 0.245+/-0.031% and 0.225+/-0.052% in the 3.6, 4.5, 5.8 and 8.0 micron IRAC bands respectively. We combine these measurements with the recently published Kepler secondary eclipse measurement, and generate atmospheric models for the day-side of the planet that are consistent with both the optical and infrared measurements. The data are best fit by models with a temperature inversion, as expected from the high incident flux. The models predict a low optical albedo of ~< 0.13, with subsolar abundances of Na, K, TiO and VO. We also find that the best fitting models predict that 10% of the absorbed stellar flux is redistributed to the night side of the planet, which is qualitatively consistent with the inefficient day-night redistribution apparent in the Kepler phase curve. Models without thermal inversions fit the data only at the 1.25 sigma level, and also require an overabundance of methane, which is not expected in the very hot atmosphere of HAT-P-7b. We also analyze the eight transits of HAT-P-7b present in the EPOXI dataset and improve the constraints on the system parameters, finding a period of P = 2.2047308+/-0.0000025 days, a stellar radius of R* = 1.824+/-0.089Rsun, a planetary radius of Rp = 1.342+/-0.068RJup and an inclination of i = 85.7+3.5-2.2 deg.Comment: 21 pages, 8 figures, accepted by the Astrophysical Journa

    African ancestry allelic variation at the MYH9 gene contributes to increased susceptibility to non-diabetic end-stage kidney disease in Hispanic Americans

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    Recent studies identified MYH9 as a major susceptibility gene for common forms of non-diabetic end-stage kidney disease (ESKD). A set of African ancestry DNA sequence variants comprising the E-1 haplotype, was significantly associated with ESKD. In order to determine whether African ancestry variants are also associated with disease susceptibility in admixed populations with differing genomic backgrounds, we genotyped a total of 1425 African and Hispanic American subjects comprising dialysis patients with diabetic and non-diabetic ESKD and controls, using 42 single nucleotide polymorphisms (SNPs) within the MYH9 gene and 40 genome-wide and 38 chromosome 22 ancestry informative markers. Following ancestry correction, logistic regression demonstrated that three of the E-1 SNPs are also associated with non-diabetic ESKD in the new sample sets of both African and Hispanic Americans, with a stronger association in Hispanic Americans. We also identified MYH9 SNPs that are even more powerfully associated with the disease phenotype than the E-1 SNPs. These newly associated SNPs, could be divided into those comprising a haplotype termed S-1 whose association was significant under a recessive or additive inheritance mode (rs5750248, OR 4.21, P < 0.01, Hispanic Americans, recessive), and those comprising a haplotype termed F-1 whose association was significant under a dominant or additive inheritance mode (rs11912763, OR 4.59, P < 0.01, Hispanic Americans, dominant). These findings strengthen the contention that a sequence variant of MYH9, common in populations with varying degrees of African ancestry admixture, and in strong linkage disequilibrium with the associated SNPs and haplotypes reported herein, strongly predisposes to non-diabetic ESKD

    A Spitzer Transmission Spectrum for the Exoplanet GJ 436b, Evidence for Stellar Variability, and Constraints on Dayside Flux Variations

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    In this paper we describe a uniform analysis of eight transits and eleven secondary eclipses of the extrasolar planet GJ 436b obtained in the 3.6, 4.5, and 8.0 micron bands using the IRAC instrument on the Spitzer Space Telescope between UT 2007 June 29 and UT 2009 Feb 4. We find that the best-fit transit depths for visits in the same bandpass can vary by as much as 8% of the total (4.7 sigma significance) from one epoch to the next. Although we cannot entirely rule out residual detector effects or a time-varying, high-altitude cloud layer in the planet's atmosphere as the cause of these variations, we consider the occultation of active regions on the star in a subset of the transit observations to be the most likely explanation. We reconcile the presence of magnetically active regions with the lack of significant visible or infrared flux variations from the star by proposing that the star's spin axis is tilted with respect to our line of sight, and that the planet's orbit is therefore likely to be misaligned. These observations serve to illustrate the challenges associated with transmission spectroscopy of planets orbiting late-type stars; we expect that other systems, such as GJ 1214, may display comparably variable transit depths. Our measured 8 micron secondary eclipse depths are consistent with a constant value, and we place a 1 sigma upper limit of 17% on changes in the planet's dayside flux in this band. Averaging over the eleven visits gives us an improved estimate of 0.0452% +/- 0.0027% for the secondary eclipse depth. We combine timing information from our observations with previously published data to produce a refined orbital ephemeris, and determine that the best-fit transit and eclipse times are consistent with a constant orbital period. [ABRIDGED]Comment: 26 pages, 18 figures, 7 tables in emulateapj format. Accepted for publication in Ap

    Preliminary Report: Missense mutations in the APOL gene family are associated with end stage kidney disease risk previously attributed to the MYH9 gene

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    MYH9 has been proposed as a major genetic risk locus for a spectrum of non-diabetic end stage kidney disease (ESKD). We use recently released sequences from the 1000 Genomes Project to identify two western African specific missense mutations (S342G and I384M) in the neighbouring APOL1 gene, and demonstrate that these are more strongly associated with ESKD than previously reported MYH9 variants. We also show that the distribution of these risk variants in African populations is consistent with the pattern of African ancestry ESKD risk previously attributed to the MYH9 gene. Additional associations were also found among other members of the APOL gene family, and we propose that ESKD risk is caused by western African variants in members of the APOL gene family, which evolved to confer protection against pathogens, such as Trypanosoma.Comment: 25 pages, 6 figure
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