5,144 research outputs found
Technology as an economic catalyst in rural and depressed places in Massachusetts
This paper uses case studies, including two cities (Lynn and New Bedford), a sub-city district (Roxbury) and two towns in rural Franklin County (Greenfield and Orange), to examine the role of technology as a potential economic catalyst in rural and depressed places in Massachusetts. Though the five target areas vary in size, density, geographic area, demographic characteristics and economic resources, each exhibits chronic patterns of economic distress related to the decline of manufacturing, construction and other key industries
Shot noise of interference between independent atomic systems
We study shot (counting) noise of the amplitude of interference between
independent atomic systems. In particular, for the two interfering systems the
variance of the fringe amplitude decreases as the inverse power of the number
of particles per system with the coefficient being a non-universal number. This
number depends on the details of the initial state of each system so that the
shot noise measurements can be used to distinguish between such states. We
explicitly evaluate this coefficient for the two cases of the interference
between bosons in number states and in broken symmetry states. We generalize
our analysis to the interference of multiple independent atomic systems. We
show that the variance of the interference contrast vanishes as the inverse
power of the number of the interfering systems. This result, implying high
signal to noise ratio in the interference experiments, holds both for bosons
and for fermions.Comment: 5 pages, 1 figure, final version, added a simple quantum-mechanical
argument why two independent condensates with fixed number of particles in
each must interfere in a generic experimental setu
Spin Diffusion in Trapped Gases: Anisotropy in Dipole and Quadrupole Modes
Recent experiments in a mixture of two hyperfine states of trapped Bose gases
show behavior analogous to a spin-1/2 system, including transverse spin waves
and other familiar Leggett-Rice-type effects. We have derived the kinetic
equations applicable to these systems, including the spin dependence of
interparticle interactions in the collision integral, and have solved for
spin-wave frequencies and longitudinal and transverse diffusion constants in
the Boltzmann limit. We find that, while the transverse and longitudinal
collision times for trapped Fermi gases are identical, the Bose gas shows
unusual diffusion anisotropy in both dipole and quadrupole modes. Moreover, the
lack of spin isotropy in the interactions leads to the non-conservation of
transverse spin, which in turn has novel effects on the hydrodynamic modes.Comment: 18 pages, 9 figure
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Review: \u3cem\u3ePutting Skills to Work: How to Create Good Jobs in Uncertain Times\u3c/em\u3e, by Lowe, Nichola
In the aftermath of World War II, a gradual but steady social contract emerged between labor organizations and business. This contract included commitments by the business sector to pay a living wage to workers and their families and to provide them paid vacations, medical plans, and retirement programs. Moreover, it included commitments to skill development opportunities through on-the-job training that would position these workers for upward advancement. For the most part, this contract lasted until the 1980s, when the federal government’s resistance to passing legislation requiring fair wages, the declining power of unions, strong international competition, and increased automation coalesced to the point the contract began to erode. One of the most significant benefits affected by this erosion was company-sponsored skill development. Taking the position that the nation’s educational institutions were better suited to train entry-level workers, the business community supported efforts to shift that responsibility to universities, four-year colleges, and community colleges. They were successful in this endeavor. However, while this approach prepared the worker for the world of work, it did not, and could not, provide the skill-related training specific to a company’s needs. Moreover, it did not provide new workers the opportunity to develop their skills in the context of a company’s corporate culture. The net result has been new workers entering the workforce without the required skills, leaving both employees and employers dissatisfied
Theory of cooling by flow through narrow pores
We consider the possibility of adding a stage to a dilution refrigerator to
provide additional cooling by ``filtering out'' hot atoms. Three methods are
considered: 1) Effusion, where holes having diameters larger than a mean-free
path allow atoms to pass through easily; 2) Particle waveguide-like motion
using very narrow channels that greatly restrict the quantum states of the
atoms in a channel. 3) Wall-limited diffusion through channels, in which the
wall scattering is disordered so that local density equilibrium is established
in a channel. We assume that channel dimension are smaller than the mean-free
path for atom-atom interactions. The particle waveguide and the wall-limited
diffusion methods using channels on order of the de Broglie wavelength give
cooling. Recent advances in nano-filters give this method some hope of being
practical.Comment: 10 pages, 3 figures. Corrected typos and made some minor wording
change
Shear-flow transition: the basin boundary
The structure of the basin of attraction of a stable equilibrium point is
investigated for a dynamical system (W97) often used to model transition to
turbulence in shear flows. The basin boundary contains not only an equilibrium
point Xlb but also a periodic orbit P, and it is the latter that mediates the
transition. Orbits starting near Xlb relaminarize. We offer evidence that this
is due to the extreme narrowness of the region complementary to basin of
attraction in that part of phase space near Xlb. This leads to a proposal for
interpreting the 'edge of chaos' in terms of more familiar invariant sets.Comment: 11 pages; submitted for publication in Nonlinearit
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Working Draft, The Mill and the Mill Town Pilot Feasibility Checklist: Redevelopment of Once and Future Mill Sites
This checklist was designed by the University of Massachusetts Center for Economic Development to identify how prepared a town is to revitalize its Mill buildings and to help potential developer identify priorities and viable redevelopment sites. The high volume of abandoned mills in New England demonstrates the need for creative tools to serve as a preliminary filter for redevelopment opportunities
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