Cold galaxies

We use 350 mu angular diameter estimates from Planck to test the idea that some galaxies contain exceptionally cold (10-13 K) dust, since colder dust implies a lower surface brightness radiation field illuminating the dust, and hence a greater physical extent for a given luminosity. The galaxies identified from their spectral energy distributions as containing cold dust do indeed show the expected larger 350 mu diameters. For a few cold dust galaxies where Herschel data are available we are able to use submillimetre maps or surface brightness profiles to locate the cold dust, which as expected generally lies outside the optical galaxy.Comment: 9 pages, 15 figures. Accepted for publication MNRA

Probing Spatial Variation Of The Fine-Structure Constant Using The CMB

The fine-structure constant, α, controls the strength of the electromagnetic interaction. There are extensions of the standard model in which α is dynamical on cosmological length and time scales. The physics of the cosmic microwave background (CMB) depends on the value of α. The effects of spatial variation in α on the CMB are similar to those produced by weak lensing: smoothing of the power spectrum, and generation of non-Gaussian features. These would induce a bias to estimates of the weak-lensing potential power spectrum of the CMB. Using this effect, Planck measurements of the temperature and polarization power spectrum, as well as estimates of CMB lensing, are used to place limits (95% C.L.) on the amplitude of a scale-invariant angular power spectrum of α fluctuations relative to the mean value (CαL=AαSI/[L(L+1)]) of AαSI≤1.6×10−5. The limits depend on the assumed shape of the α-fluctuation power spectrum. For example, for a white-noise angular power spectrum (CαL=AαWN), the limit is AαWN≤2.3×10−8. It is found that the response of the CMB to α fluctuations depends on a separate-universe approximation, such that theoretical predictions are only reliable for α multipoles with L≲100. An optimal trispectrum estimator can be constructed and it is found that it is only marginally more sensitive than lensing techniques for Planck but significantly more sensitive when considering the next generation of experiments. For a future CMB experiment with cosmic-variance limited polarization sensitivity (e.g., CMB-S4), the optimal estimator could detect α fluctuations with AαSI\u3e1.9×10−6 and AαWN\u3e1.4×10−9

HIV/STI Risk Factors Among African-American Students Attending Predominantly White Universities

Introduction: The majority of African American college students in the U.S. attend predominantly white institutions (PWIs). However, there is minimal research examining this population’s HIV/STI risk behaviors. The purpose of this investigation was to assess HIV/STI behavioral risk factors among African American college students (aged 18 – 24years) attending PWIs. (n = 2,568) Methods: Backwards step-wise logistic regression analyses were conducted to determine factors associated with a positive HIV/STI diagnosis (past year) among sexually active African American college students who participated in the Spring, 2006 National College Health Assessment. Findings: Nine factors were significantly associated with an HIV/STI diagnosis among African American college students attending PWIs. Different risk factors were associated with having a HIV/STI diagnosis among African American male and female college students. These results may be useful to HIV/STIs prevention programs targeting African American college students attending PWIs

Ion bombardment experiments suggesting an origin for organic particles in pre-cometary and cometary ices

During the Giotto and Vega encounters with Comet Halley both organic particles called CHON and energetic ions were detected. The acceleration of ions to hundreds of keV in the vicinity of the bow shock and near the nucleus may be a demonstration of a situation occurring in the early solar system (perhaps during the T Tauri stage) that led to the formation of organic particles only now released. Utilizing a Van de Graaff accelerator and a target chamber having cryogenic and mass spectrometer capabilities, frozen gases were bombarded at 10 K with 175 keV protons with the result that fluffy solid material remains after sublimation of the ice. Initial experiments were carried out with a gas mixture in parts of 170 carbon monoxide, 170 argon, 25 water, 20 nitrogen, and 15 methane formulated to reflect an interstellar composition in experiments involving the freezing out of the products of a plasma. The plasma experiments resulted in a varnish-like film residue that exhibited luminescence when excited with ultraviolet radiation, while the ion bombardment created particulate material that was not luminescent

Potential Risks Inherent in Robotic Process Automation

Robotic process automation (RPA) uses automation technologies to perform tasks typically performed by humans. Although such technology has been instrumental in expediting business operations and lowering costs, it has also created several risks that warrant scrutiny. When discussing the drawbacks of automation, many will point to the number of jobs lost to the influx of automation. However, there are technology risks that organizations must consider such as fraud and cybersecurity. Fraudsters may utilize RPA to commit more novel and subtle technological and cyber security fraud. Organizations may implement internal control measures to prevent or mitigate such schemes, segregation of duties, and change management. RPA has many benefits, but the effective use of such technology will ultimately come down to how businesses adapt to risks in such an ever-changing business environment

Legitimating space: art and the politics of place

Rock art, graffiti, and other emplaced works of art bring people together at specific places. This type of art allows for encounters between people in their absence, and thus presents a range of possibilities for making statements about specific places and those who occupy or visit. This opens the possibility for issues of legitimation to become implicitly or explicitly articulated. However, the legitimate use of space, and the legitimate employment of art, can vary drastically across different contexts. Here, the paper discusses a range of different strategies of art and legitimation in three case studies from India, California, and Spai

Local existence for the non-resistive MHD equations in nearly optimal Sobolev spaces

This paper establishes the local-in-time existence and uniqueness of solutions to the viscous, non-resistive magnetohydrodynamics (MHD) equations in RdRd , where d = 2, 3, with initial data B0∈Hs(Rd)B0∈Hs(Rd) and u0∈Hs−1+ϵ(Rd)u0∈Hs−1+ϵ(Rd) for s>d/2s>d/2 and any 0<ϵ<10<ϵ<1 . The proof relies on maximal regularity estimates for the Stokes equation. The obstruction to taking ϵ=0ϵ=0 is explained by the failure of solutions of the heat equation with initial data u0∈Hs−1u0∈Hs−1 to satisfy u∈L1(0,T;Hs+1)u∈L1(0,T;Hs+1) ; we provide an explicit example of this phenomenon