1,058 research outputs found

    Gamma-ray signatures of annihilation to charged leptons in dark matter substructure

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    Due to their higher concentrations and small internal velocities, Milky Way subhalos can be at least as important as the smooth halo in accounting for the GeV positron excess via dark matter annihilation. After showing how this can be achieved in various scenarios, including in Sommerfeld models, we demonstrate that, in this case, the diffuse inverse-Compton emission resulting from electrons and positrons produced in substructure leads to a nearly-isotropic signal close to the level of the isotropic GeV gamma-ray background seen by Fermi. Moreover, we show that HESS cosmic-ray electron measurements can be used to constrain multi-TeV internal bremsstrahlung gamma rays arising from annihilation to charged leptons.Comment: 8 pages, 4 figures; minor updates to match published versio

    Research and education in management of large-scale technical programs

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    A research effort is reported which was conducted by NASA in conjunction with Drexel University, and which was aimed at an improved understanding of large scale systems technology and management

    Development of an Oral Health Survey: Columbus, Ohio

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    This article describes the method used to develop and implement a local oral health survey (Columbus, Ohio) conducted in 1986. With the shift in the national dental disease pattern in the past decade, local oral health information is essential for program planning purposes. A collaborative effort by a city health department, a state health department, a dental school, and a school of public health demonstrated how this group worked harmoniously in a relatively inexpensive venture to determine the oral status of various age groups (grades 1–2, grades 6–7, age 35–44, and age 65 +). This information provided part of the framework for a five-year dental plan at the Columbus Health Department. The survey design will serve as a basis for conducting a similar survey statewide. Modifications of existing oral health survey instruments are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65714/1/j.1752-7325.1988.tb03177.x.pd

    Statement on the Effects of Law Enforcement in School Settings

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    School-based law enforcement (SBLE) have become increasingly common in U.S. schools over recent decades despite the controversy surrounding their presence and lack of consensus around their associated benefits and harms. Drawing on the history and evidence base regarding SBLE, we advocate for an end to SBLE programs. Grounding our argument in principles of Community Psychology and positive youth development, we outline how the presence and actions of SBLE negatively affect individual students as well as school systems, with particularly harmful outcomes for students with minoritized and marginalized identities. Research on SBLE and school crime does not provide consistent evidence of positive impacts, and many studies find null effects for the relationship between SBLE and school crime or increases in crime and violence in schools. Though funding for SBLE is often prompted by high-profile acts of gun violence in schools, evidence suggests that SBLE neither prevents these incidents, nor lessens the severity when they do occur. Thus, we advocate for removing law enforcement from school settings and redirecting resources into inclusive, evidence-informed responses that are generally safer and more effective than SBLE. We close by outlining the policy landscape governing SBLE programs and ways communities can lobby for change

    Analysis and Modification of Amorphous and Partially-Crystalline Thin Films

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    Thin films of light atomic weight elements in amorphous, partially-crystalline, or crystalline forms have applications in a broad range of technologies. For example, amorphous tetrahedral carbon (a-tC) and polymeric thin films impact electronic materials technology as electron- and light-emitting device elements, respectively. A lack of crystallinity introduces complexity in the experimental and theoretical characterization of these materials but is not necessarily a limiting factor in their performance. While the growth process is clearly a major factor governing the physical properties of a film, interactions with the substrate are also important, so surface and interface analysis provides an important complement to bulk measurements. This paper focuses on several approaches in the characterization and modification of thin films made possible by recent experimental advances. The structural and electronic properties of two model systems are considered as examples: a-tC thin films grown by pulsed laser deposition (PLD) and polyaniline thin films grown by vapor deposition. First, scanning probe microscopies and X-ray scattering are used to investigate the structural aspects of a-tC films as a function of PLD growth conditions. The possible connection of nanoscale surface modification and characterization with electron emission properties will be discussed. Second, the results of inelastic scattering spectroscopy and other surface techniques will be discussed to obtain information on both interfacial aspects of the growth of polyaniline thin films and microscopic and macroscopic aspects of electrical conductivity upon doping. Comparisons will be made with other studies that address properties of analogous crystalline systems as appropriate. A brief assessment of the broader problem of analyzing these systems will be given

    Automatic differentiation for gradient-based optimization of radiatively heated microelectronics manufacturing equipment

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    Automatic differentiation is applied to the optimal design of microelectronic manufacturing equipment. The performance of nonlinear, least-squares optimization methods is compared between numerical and analytical gradient approaches. The optimization calculations are performed by running large finite-element codes in an object-oriented optimization environment. The Adifor automatic differentiation tool is used to generate analytic derivatives for the finite-element codes. The performance results support previous observations that automatic differentiation becomes beneficial as the number of optimization parameters increases. The increase in speed, relative to numerical differences, has a limited value and results are reported for two different analysis codes

    Attitudes towards medication non-adherence in elderly kidney transplant patients: A Q methodology study

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    Background. Non-adherence to the post-transplant regime is a common problem in kidney transplant patients and may lead to rejection or even graft failure. This study investigated attitudes towards the post-transplant regime of immunosuppressive medication among the ever growing population of elderly kidney recipients.Methods. Q methodology was used to explore attitude profiles. Participants (> 65 years) were asked to rank-order opinion statements on issues associated with (non-)adherence. The rankings were subject to by-person factor analysis, and the resulting factors were interpreted and described as attitudes.Results. Twenty-six elderly renal transplant recipients participated in the study. All passed the Mini-Mental
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