65,125 research outputs found
The American Community Survey
Analytical data report #15 is the latest in a series of bulletins designed to complement our traditional data releases. The American Community Survey (ACS) is a continuous household survey conducted by the United States Census Bureau that will replace the long-form of the traditional decennial Census. ADR #15 provides background information on the ACS and the benefits and challenges associated with its use. The report also reviews some of the estimates currently available for the region's nine counties and six largest municipalities and, based on this data, discusses demographic changes in the Delaware Valley between 2000 and 2006
Sudden Critical Current Drops Induced in S/F Structures
In the search for new physical properties of S/F structures, we have found
that the superconductor critical current can be controlled by the domain state
of the neighboring ferromagnet. The superconductor is a thin wire of thickness
d_{s} ~ 2 xi_{S}. Nb/Co and Nb/Py (Permalloy Ni_{80}Fe_{20}) bilayer structures
were grown with a significant magnetic anisotropy. Critical current
measurements of Nb/Co structures with ferromagnet thickness d_{F} > 30nm show
sudden drops in two very defined steps when the measurements are made along the
hard axes direction (i.e. current track parallel to hard anisotropy axes
direction). These drops disappear when they are made along the easy axis
direction or when the ferromagnet thickness is below 30nm. The drops are
accompanied by vortex flux flow. In addition magnetorestistance measurements
close to Tc show a sharp increase near saturation fields of the ferromagnet.
Similar results are reproduced in Nb/Py bilayer structure with the ferromagnet
thickness d_{F} ~ 50nm along the easy anisotropy axes. These results are
explained as being due to spontaneous vortex formation and flow induced by
Bloch domain walls of the ferromagnet underneath. We argue these Bloch domain
walls produce a 2D vortex-antivortex lattice structure.Comment: 6 pages, 6 figure
Computer performance analysis - Measurement objectives and tools
Objectives and measurements in computer performance analysi
Amplitude control of quantum interference
Usually, the oscillations of interference effects are controlled by relative
phases. We show that varying the amplitudes of quantum waves, for instance by
changing the reflectivity of beam splitters, can also lead to quantum
oscillations and even to Bell violations of local realism. We first study
theoretically a generalization of the Hong-Ou-Mandel experiment to arbitrary
source numbers and beam splitter transmittivity. We then consider a Bell type
experiment with two independent sources, and find strong violations of local
realism for arbitrarily large source number ; for small , one operator
measures essentially the relative phase of the sources and the other their
intensities. Since, experimentally, one can measure the parity of the number of
atoms in an optical lattice more easily than the number itself, we assume that
the detectors measure parity.Comment: 4 pages; 4 figure
E-Learning Works - Exactly How Well Depends on its Unique Features and Barriers
Key Findings: E-learning is comparable to traditional teacher-led classroom instruction in terms of effectiveness. E-learning has specific features that may influence learning: content, immersion, interactivity, and communication. Barriers to e-learning adoption include fraud and cheating, digital divides and their impact on low income and underprepared students, and cost issues
E-Learning in Postsecondary Education
Over the past decade postsecondary education has been moving increasingly from the class room to online. During the fall 2010 term 31 percent of U.S. college students took at least one online course. The primary reasons for the growth of e-learning in the nation\u27s colleges and universities include the desire of those institutions to generate new revenue streams, improve access, and offer students greater scheduling flexibility. Yet the growth of e-learning has been accompanied by a continuing debate about its effectiveness and by the recognition that a number of barriers impede its widespread adoption in higher education
Bounds for Non-Locality Distillation Protocols
Non-locality can be quantified by the violation of a Bell inequality. Since
this violation may be amplified by local operations an alternative measure has
been proposed - distillable non-locality. The alternative measure is difficult
to calculate exactly due to the double exponential growth of the parameter
space. In this article we give a way to bound the distillable non-locality of a
resource by the solutions to a related optimization problem. Our upper bounds
are exponentially easier to compute than the exact value and are shown to be
meaningful in general and tight in some cases.Comment: 8 pages, 3 figures; small changes in introduction and application
section due to the exact verification of distillation bounds using a symbolic
computation package (Maple 14); added journal re
Estimating Water Demand Schedules for Selected Industries in Arkansas
Water demand functions for the paper and chemical industries in the state of Arkansas were estimated utilizing data collected from individual plants throughout the state. Regression analysis was used to estimate demand functions from a data base which included information on intake and gross water use by source, recirculated water use, costs of acquiring, treating, and discharging water, plant output, employment, and level of technology. The demand for intake water was estimated as an exponential function of average water costs and the level of technology primarily. Price elasticities of demand were estimated as approximately equal to one for both industries. The results of this study could be used to determine the effects of various public policies on the withdrawal of water for industrial purposes
Generalized Derivations with Commutativity and Anti-commutativity Conditions
Let R be a prime ring with 1, with char(R) ≠ 2; and let F : R → R be a generalized derivation. We determine when one of the following holds for all x,y ∈ R: (i) [F(x); F(y)] = 0; (ii) F(x)ΟF(y) = 0;
(iii) F(x) Ο F(y) = x Ο y .</p
- …