37,306 research outputs found
Slepton Flavor Physics at Linear Colliders
If low energy supersymmetry is realized in nature it is possible that a first
generation linear collider will only have access to some of the superpartners
with electroweak quantum numbers. Among these, sleptons can provide sensitive
probes for lepton flavor violation through potentially dramatic lepton
violating signals. Theoretical proposals to understand the absence of low
energy quark and lepton flavor changing neutral currents are surveyed and many
are found to predict observable slepton flavor violating signals at linear
colliders. The observation or absence of such sflavor violation will thus
provide important indirect clues to very high energy physics. Previous analyses
of slepton flavor oscillations are also extended to include the effects of
finite width and mass differences.Comment: 7 pages, no figures, uses RevTeX4. Contribution to Snowmass 200
Living Standards in Black and White: Evidence from the Heights of Ohio Prison Inmates, 1829 – 1913
The use of height data to measure living standards is now a well-established method in the economic history literature. Moreover, a number of core findings in this literature are widely agreed upon. There are still some populations, places, and times, however, for which anthropometric evidence remains thin. One example is African-Americans in the Northern US in the 1800s. Here, we use new data from the state prison in Ohio to track heights of black and white men from 1829 to 1913. We corroborate the well-known mid-century height decline among white men in Ohio, found by Steckel and Haurin (1994) using National Guard data. We find that black men in Ohio were shorter than white men, throughout the century and controlling for a number of characteristics. We also find a pattern of height decline in mid-century similar to that found for white men.
Algebraic properties of generalized Rijndael-like ciphers
We provide conditions under which the set of Rijndael functions considered as
permutations of the state space and based on operations of the finite field
\GF (p^k) ( a prime number) is not closed under functional
composition. These conditions justify using a sequential multiple encryption to
strengthen the AES (Rijndael block cipher with specific block sizes) in case
AES became practically insecure. In Sparr and Wernsdorf (2008), R. Sparr and R.
Wernsdorf provided conditions under which the group generated by the
Rijndael-like round functions based on operations of the finite field \GF
(2^k) is equal to the alternating group on the state space. In this paper we
provide conditions under which the group generated by the Rijndael-like round
functions based on operations of the finite field \GF (p^k) () is
equal to the symmetric group or the alternating group on the state space.Comment: 22 pages; Prelim0
Simulated X-ray Cluster Temperature Maps
Temperature maps are presented of the 9 largest clusters in the mock
catalogues of Muanwong et al. for both the Preheating and Radiative models. The
maps show that clusters are not smooth, featureless systems, but contain a
variety of substructure which should be observable. The surface brightness
contours are generally elliptical and features that are seen include cold
clumps, hot spiral features, and cold fronts. Profiles of emission-weighted
temperature, surface brightness and emission-weighted pressure across the
surface brightness discontinuities seen in one of the bimodal clusters are
consistent with the cold front in Abell 2142 observed by Markevitch et al.Comment: Submitted to Monthly Notices Royal Astronomical Societ
Isogeometric B\'ezier dual mortaring: Refineable higher-order spline dual bases and weakly continuous geometry
In this paper we develop the isogeometric B\'ezier dual mortar method. It is
based on B\'ezier extraction and projection and is applicable to any spline
space which can be represented in B\'ezier form (i.e., NURBS, T-splines,
LR-splines, etc.). The approach weakly enforces the continuity of the solution
at patch interfaces and the error can be adaptively controlled by leveraging
the refineability of the underlying dual spline basis without introducing any
additional degrees of freedom. We also develop weakly continuous geometry as a
particular application of isogeometric B\'ezier dual mortaring. Weakly
continuous geometry is a geometry description where the weak continuity
constraints are built into properly modified B\'ezier extraction operators. As
a result, multi-patch models can be processed in a solver directly without
having to employ a mortaring solution strategy. We demonstrate the utility of
the approach on several challenging benchmark problems. Keywords: Mortar
methods, Isogeometric analysis, B\'ezier extraction, B\'ezier projectio
Near-infrared Variability among YSOs in the Star Formation Region Cygnus OB7
We present an analysis of near-infrared time-series photometry in J, H, and K
bands for about 100 epochs of a 1 square degree region of the Lynds 1003/1004
dark cloud in the Cygnus OB7 region. Augmented by data from the Wide-field
Infrared Survey Explorer (WISE), we identify 96 candidate disk bearing young
stellar objects (YSOs) in the region. Of these, 30 are clearly Class I or
earlier. Using the Wide-Field imaging CAMera (WFCAM) on the United Kingdom
InfraRed Telescope (UKIRT), we were able to obtain photometry over three
observing seasons, with photometric uncertainty better than 0.05 mag down to J
~17. We study detailed light curves and color trajectories of ~50 of the YSOs
in the monitored field. We investigate the variability and periodicity of the
YSOs and find the data are consistent with all YSOs being variable in these
wavelengths on time scales of a few years. We divide the variability into four
observational classes: 1) stars with periodic variability stable over long
timescales, 2) variables which exhibit short-lived cyclic behavior, 3) long
duration variables, and 4) stochastic variables. Some YSO variability defies
simple classification. We can explain much of the observed variability as being
due to dynamic and rotational changes in the disk, including an asymmetric or
changing blocking fraction, changes to the inner disk hole size, as well as
changes to the accretion rate. Overall, we find that the Class I:Class II ratio
of the cluster is consistent with an age of < 1Myr, with at least one
individual, wildly varying, source ~ 100,000 yr old. We have also discovered a
Class II eclipsing binary system with a period of 17.87 days.Comment: ApJ accepted: 44 pages includes 5 tables and 16 figures. Some figures
condensed for Astro/p
Theoretical Basis for the CE-QUAL-W2 River Basin Model
The primary objective of this research is to integrate a riverine model into the existing W2 code that would provide the capability for modeling entire watersheds. This task was accomplished by the following steps:
• Formal derivation of governing equations and solution algorithm with general channel slope
• Detailed analysis of algorithm for linking branches and smooth implementation of boundary conditions between branches
• Algorithm development and changes to basic model code (including branch definitions with slope, slope correction to solution algorithm, transfer of momentum between internal branches)
These tasks were performed with the following constraints and initiatives:
• Utilize the same solution algorithms as the existing code for hydrodynamics and water quality for the riverine system
• Allow momentum transfer between adjacent branches for internal head boundary conditions
• Refine the turbulence closure hypothesis for riverine section
Coexpression of rat P2X2 and P2X6 subunits in Xenopus oocytes.
Transcripts for P2X(2) and P2X(6) subunits are present in rat CNS and frequently colocalize in the same brainstem nuclei. When rat P2X(2) (rP2X(2)) and rat P2X(6) (rP2X(6)) receptors were expressed individually in Xenopus oocytes and studied under voltage-clamp conditions, only homomeric rP2X(2) receptors were fully functional and gave rise to large inward currents (2-3 microA) to extracellular ATP. Coexpression of rP2X(2) and rP2X(6) subunits in Xenopus oocytes resulted in a heteromeric rP2X(2/6) receptor, which showed a significantly different phenotype from the wild-type rP2X(2) receptor. Differences included reduction in agonist potencies and, in some cases (e.g., Ap(4)A), significant loss of agonist activity. ATP-evoked inward currents were biphasic at the heteromeric rP2X(2/6) receptor, particularly when Zn(2+) ions were present or extracellular pH was lowered. The pH range was narrower for H(+) enhancement of ATP responses at the heteromeric rP2X(2/6) receptor. Also, H(+) ions inhibited ATP responses at low pH levels (<pH 6.3). The pH-dependent blocking activity of suramin was changed at this heteromeric receptor, although the potentiating effect of Zn(2+) on ATP responses was unchanged. Thus, the rP2X(2/6) receptor is a functionally modified P2X(2)-like receptor with a distinct pattern of pH modulation of ATP activation and suramin blockade. Although homomeric P2X(6) receptors function poorly, the P2X(6) subunit can contribute to functional heteromeric P2X channels and may influence the phenotype of native P2X receptors in those cells in which it is expressed
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