3,888 research outputs found
Detecting the Attenuation of Blazar Gamma-ray Emission by Extragalactic Background Light with GLAST
Gamma rays with energy above 10 GeV interact with optical-UV photons
resulting in pair production. Therefore, a large sample of high redshift
sources of these gamma rays can be used to probe the extragalactic background
starlight (EBL) by examining the redshift dependence of the attenuation of the
flux above 10 GeV. GLAST, the next generation high-energy gamma-ray telescope,
will have the unique capability to detect thousands of gamma-ray blazars to
redshifts of at least z=4, with sufficient angular resolution to allow
identification of a large fraction of their optical counterparts. By combining
established models of the gamma-ray blazar luminosity function, two different
calculations of the high energy gamma-ray opacity due to EBL absorption, and
the expected GLAST instrument performance to produce simulated fluxes and
redshifts for the blazars that GLAST would detect, we demonstrate that these
gamma-ray blazars have the potential to be a highly effective probe of the
optical-UV EBL.Comment: 15 pages, AASTeX, 3 eps figures, accepted for publication in Ap
STEM in General Education: Does Mathematics Competence Influence Course Selection
Many students enroll in college programs to prepare for their future careers. All are required to complete general studies courses. At one university, technology and STEM courses fulfill a part of the natural science and technology general education requirements. This study uses a survey design to explore why 332 students chose to enroll in a STEM technology course. Results found most enroll because their advisor suggests the course, it meets a general education major requirement, and the course is offered at a convenient time. Fewer enroll in the course because they would like to find out more about STEM fields, be exposed to potential careers, or because of the implicit need to study STEM subjects. Student mathematics skills were analyzed to determine if these skills influenced their choice for selecting this technology STEM course
A new model for magnetoreception
Certain migratory birds can sense the earth's magnetic field. The nature of
this process is not yet properly understood. Here we offer a simple explanation
according to which birds literally `see' the local magnetic field: Our model
relates the well-established radical pair hypothesis to the phenomenon of
Haidinger's brush, a capacity to see the polarisation of light. This new
picture explains recent surprising experimental data indicating long lifetimes
for the radical pair. Moreover there is a clear evolutionary path toward this
field sensing mechanism: it is an enhancement of a weak effect that may be
present in many species.Comment: 8 pages, 5 figures, version of final published pape
Generalized linear competition: From pass-through to policy
Economic policy and shifts in input market prices often have significant effects on the marginal costs of firms and can prompt strategic responses that make their impact hard to predict. We introduce “generalized linear competition” (GLC), a new model th
Scoping biological indicators of soil quality Phase II. Defra Final Contract Report SP0534
This report presents results from a field assessment of a limited suite of potential biological indicators of soil quality to investigate their suitability for national-scale soil monitoring
Sensitivity to new supersymmetric thresholds through flavour and CP violating physics
Treating the MSSM as an effective theory below a threshold scale Lambda, we
study the consequences of having dimension-five operators in the superpotential
for flavour and CP-violating processes. Below the supersymmetric threshold such
terms generate flavour changing and/or CP-odd effective operators of dimension
six composed from the Standard Model fermions, that have the interesting
property of decoupling linearly with the threshold scale, i.e. as 1/(Lambda
m_soft), where m_soft is the scale of soft supersymmetry breaking. The
assumption of weak-scale supersymmetry, together with the stringent limits on
electric dipole moments and lepton flavour-violating processes, then provides
sensitivity to Lambda as high as 10^7-10^9 GeV. We discuss the varying
sensitivity to these scales within several MSSM benchmark scenarios and also
outline the classes of UV physics which could generate these operators.Comment: 28 pages, 9 figure
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