55,905 research outputs found
Measuring Confidentiality Risks in Census Data
Two trends have been on a collision course over the recent past. The first is the increasing demand by researchers for greater detail and flexibility in outputs from the decennial Census of Population. The second is the need felt by the Census Offices to demonstrate more clearly that Census data have been explicitly protected from the risk of disclosure of information about individuals. To reconcile these competing trends the authors propose a statistical measure of risks of disclosure implicit in the release of aggregate census data. The ideas of risk measurement are first developed for microdata where there is prior experience and then modified to measure risk in tables of counts. To make sure that the theoretical ideas are fully expounded, the authors develop small worked example. The risk measure purposed here is currently being tested out with synthetic and a real Census microdata. It is hoped that this approach will both refocus the census confidentiality debate and contribute to the safe use of user defined flexible census output geographies
Measuring Confidentiality Risks in Census Data
Two trends have been on a collision course over the recent past. The first is the increasing demand by researchers for greater detail and flexibility in outputs from the decennial Census of Population. The second is the need felt by the Census Offices to demonstrate more clearly that Census data have been explicitly protected from the risk of disclosure of information about individuals. To reconcile these competing trends the authors propose a statistical measure of risks of disclosure implicit in the release of aggregate census data. The ideas of risk measurement are first developed for microdata where there is prior experience and then modified to measure risk in tables of counts. To make sure that the theoretical ideas are fully expounded, the authors develop small worked example. The risk measure purposed here is currently being tested out with synthetic and a real Census microdata. It is hoped that this approach will both refocus the census confidentiality debate and contribute to the safe use of user defined flexible census output geographies
A bodner-partom visco-plastic dynamic sphere benchmark problem
Developing benchmark analytic solutions for problems in solid and fluid mechanics is very important for the purpose of testing and verifying computational physics codes. Our primary objective in this research is to obtain a benchmark analytic solution to the equation of motion in radially symmetric spherical coordinates. An analytic solution for the dynamic response of a sphere composed of an isotropic visco-plastic material and subjected to spherically symmetric boundary conditions is developed and implemented. The radial displacement u is computed by solving the equation of motion, a linear second-order hyperbolic PDE. The plastic strains εp and εp are computed by solving two non-linear first-order ODEs in time. We obtain a solution for u in terms of the plastic strain components and boundary conditions in the form of an infinite series. Computationally, at each time step, we set up an iteration scheme to solve the PDE-ODE system. The linear momentum equation is solved using the plastic strains from the previous iteration, then the plastic strain equations are solved numerically using the new displacement. We demonstrate the accuracy and
convergence of our benchmark solution under spatial mesh, time step, and eigenmode refinement
Electrical isolation of GaN by MeV ion irradiation
The evolution of sheet resistance of n-type GaN epilayers exposed to irradiation with MeV H, Li, C, and O ions is studied in situ. Results show that the threshold dose necessary for complete isolation linearly depends on the original free electron concentration and reciprocally depends on the number of atomic displacements produced by ion irradiation. Furthermore, such isolation is stable to rapid thermal annealing at temperatures up to 900 °C. In addition to providing a better understanding of the physical mechanisms responsible for electrical isolation, these results can be used for choosing implant conditions necessary for an effective electrical isolation of GaN-based devices.This work was partly supported by Conselho Nacional
de Pesquisas (CNPq, Brazil) under Contract No. 200541/
99-4
Highly-improved lattice field-strength tensor
We derive an O(a^4)-improved lattice version of the continuum field-strength
tensor. Discretization errors are reduced via the combination of several clover
terms of various sizes, complemented by tadpole improvement. The resulting
improved field-strength tensor is used to construct O(a^4)-improved topological
charge and action operators. We compare the values attained by these operators
as we cool several configurations to self-duality with a previously defined
highly-improved action and assess the relative scale of the remaining
discretization errors.Comment: 22 pages, 7 postscript figure
New HiggsBounds from LEP and the Tevatron
We review the program HiggsBounds that tests theoretical predictions of
models with arbitrary Higgs sectors against the exclusion bounds obtained from
the Higgs searches at LEP and the Tevatron. We explicitly list the bounds that
have been added after the first release of HiggsBounds.Comment: 4 pages, talk given at SUSY09, Boston, June 200
Responses of Coccidia-Vaccinated Broilers to Essential Oil Blends Supplementation up to Forty-Nine Days of Age
Coccidiosis control may become a greater problem as the use of growth-promoting antibiotics (GPA) and ionophores declines. Vaccination with live oocysts may turn into a popular alternative to the use of coccidiostats in broilers, although cocci vaccination is frequently linked to temporary lower performance in young flocks. This experiment evaluates the dietary supplementation of 2 specific essential oil (EO) blends (Crina Poultry and Crina Alternate), either as alternatives to GPA and ionophores (BMD + Coban) or as feed additives that help to improve the performance of cocci-vaccinated broilers. Live performance and lesion scores were observed. These 2 specific EO blends differ in their efficacy to promote growth. Chickens that were not cocci vaccinated and were fed Crina Poultry had better feed conversion ratio (FCR) than the unmedicated control treatment in the starter period. The same EO improved FCR in cocci-vaccinated birds in the finisher period in comparison to the negative control group, but those responses were not significantly different from other treatments or significant at 49 d of age. No significant differences were observed in lesion scores at 37 d. Diets supplemented with a GPA-ionophore combination consistently supported the best BW gain and FCR in each period and the entire grow-out period. No significant beneficial or deleterious effects on live performance were observed due to these specific EO blends in cocci-vaccinated broilers
Graphene as a Novel Single Photon Counting Optical and IR Photodetector
Bilayer graphene has many unique optoelectronic properties , including a
tuneable band gap, that make it possible to develop new and more efficient
optical and nanoelectronic devices. We have developed a Monte Carlo simulation
for a single photon counting photodetector incorporating bilayer graphene. Our
results show that, conceptually it would be feasible to manufacture a single
photon counting photodetector (with colour sensitivity) from bilayer graphene
for use across both optical and infrared wavelengths. Our concept exploits the
high carrier mobility and tuneable band gap associated with a bilayer graphene
approach. This allows for low noise operation over a range of cryogenic
temperatures, thereby reducing the cost of cryogens with a trade off between
resolution and operating temperature. The results from this theoretical study
now enable us to progress onto the manufacture of prototype photon counters at
optical and IR wavelengths that may have the potential to be groundbreaking in
some scientific research applications.Comment: Conference Proceeding in Graphene-Based Technologies, 201
COMPTEL Observations of the Gamma-Ray Blazar PKS 1622-297
We report results of observations and analyses on the gamma-ray blazar PKS
1622-297, with emphasis on the COMPTEL data (0.75 - 30 MeV) collected between
April 1991 and November 1997. PKS 1622-297 was detected as a source of
gamma-rays by the EGRET experiment aboard CGRO in 1995 during a gamma-ray
outburst at energies above 100 MeV lasting for five weeks.
In this time period the blazar was significantly (~ 5.9 sigma) detected by
COMPTEL at 10-30 MeV. At lower COMPTEL energies the detection is marginal,
resulting in a hard MeV spectrum.
The combined COMPTEL/EGRET energy spectrum shows a break at MeV energies. The
broad-band spectrum (radio - gamma-rays) shows that the gamma-ray emission
dominates the overall power output. On top of the 5-week gamma-ray outburst,
EGRET detected a huge flare lasting for > 1 day. Enhanced MeV emission (10 - 30
MeV) is found near the time of this flare, suggesting a possible time delay
with respect to the emission above 100 MeV. Outside the 5-week flaring period
in 1995, we do not detect MeV emission from PKS 1622-297.Comment: 10 pages including 9 figures, accepted for publication in A&
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