429 research outputs found
Information channels in labor markets: On the resilience of referral hiring
Economists and sociologists disagree over markets' potential to assume functions typically performed by networks of personal connections, first among them the transmission of information. This paper begins from a model of labor markets where social ties are stronger between similar individuals and firms employing productive workers prefer to rely on personal referrals than to hire on the anonymous market (Montgomery (1991)). However, we allow workers in the market to engage in a costly action that can signal their high productivity, and ask whether the possibility of signaling reduces the reliance on the network. We find that the network is remarkably resilient. To be effective signaling must fulfill two contradictory requirements: unless the signal is extremely precise, it must be expensive or it is not informative; but it must be cheap, or the network can undercut it
Separation of Low Reynolds Number Flows Around a Corner
It was shown experimentally that low Reynolds number flows around a sharp corner do not separate at the corner, and separation points move downstream from the corner with decrease in Reynolds number. For the flow in a channel with a backward-facing step, the experimental results showed a good agreement with those of numerical calculation for the position of separation points and the length of standing vortices
Commutativity of association schemes of prime square order having non-trivial thin closed subsets
The original publication is available at www.springerlink.comArticleJOURNAL OF ALGEBRAIC COMBINATORICS. 27(3): 307-316 (2008)journal articl
Microbial and operational response of an anaerobic fixed bed digester to oleic acid overloads
The effect of oleic acid overloads on biomass accumulation and activity in an anaerobic filter was investigated. An anaerobic
fixed-bed reactor specially designed to allow the regular withdrawal of accumulated biomass was used for that purpose. Organic
and hydraulic shocks were performed during four days, by stepwise increasing the substrate concentration from 4000 to 20 000
mg COD/l or by reducing the hydraulic retention time from 16 to 3.2 h. During the organic shock, operational performance was
more affected than in the hydraulic one, which was the result of the higher degree of inhibition detected in the acetoclastic,
hydrogenophilic and syntrophic activities. The ratio adhered/total biomass remained between 17 and 32% during the hydraulic
shock, and between 13 and 60% during the organic shock, suggesting a more stable biofilm during the hydraulic shock. A long
time (900 h) after the hydraulic shock, hydrogenophilic and syntrophic activities recovered to higher values than before the shock,
but after the organic shock only acetoclastic activity recovered pre-shock values. Hydraulic shock induced an increase in tolerance
to oleic acid toxicity, evidenced by an increase in the toxicity limit (IC50) from 140+/-30 to 215+/-25 mg/l.Fundação de Ciência e Tecnologia
A Monopole Instanton-Like Effect in the ABJM Model
Making use of ansatzs for the form fields in the 10d type IIA supergravity
version of the ABJM model, we come with a solution in the Euclidean signature
recognized as a monopole instanton-like object. Indeed we will see that we can
have a (anti) self-dual solution at a special limit. While as a topological
object, its back-reaction on the original background should be ignorable, we
show the energy-momentum tensors vanish exactly. On the field theory side, the
best counterpart is an U(1) gauge field of a gauge transformation. To adjust
with bulk, the gauge field must prompt to a dynamic one without adding any
kinetic term for this dual photon except a marginal, abelian AB-type
Chern-Simons term on the boundary. We will see how both side solutions match
next to another confirmation from some earlier works of this vortex-particle
duality.Comment: 15 pages, minor changes of some formulas, few typos fixed, and a
reference adde
Vortices, Q-balls and Domain Walls on Dielectric M2-branes
We study BPS solitons in N=6 U(N) \times U(N) Chern-Simons-matter theory
deformed by an F-term mass. The F-term mass generically breaks N=6
supersymmetry down to N=2. At vacua, M2-branes are polarized into a fuzzy S^3
forming a spherical M5-brane with topology \mathbf{R}^{1,2} \times S^3. The
polarization is interpreted as Myers' dielectric effect caused by an
anti-self-dual 4-form flux T_4 in the eleven-dimensional supergravity. Assuming
a polarized M2-brane configuration, the model effectively reduces to the
well-known abelian Chern-Simons-Higgs model studied in detail by
Jackiw-Lee-Weinberg. We find that the potential for the fuzzy S^3 radius agrees
with the one calculated from the M5-brane point of view at large N. This
effective model admits not only BPS topological vortex and domain wall
solutions but also non-topological solitons that keep 1/4 of the manifest N=2
supersymmetry. We also comment on the reduction of our configuration to ten
dimensions.Comment: references added, minor modification
Carrier concentrations in Bi_{2}Sr_{2-z}La_{z}CuO_{6+\delta} single crystals and their relation to Hall coefficient and thermopower
We measured the thermopower S and the Hall coefficients R_H of
Bi_{2}Sr_{2-z}La_{z}CuO_{6+\delta} (BSLCO) single crystals in a wide doping
range, in an effort to identify the actual hole concentrations per Cu, p, in
this system. It is found that the "universal" relation between the
room-temperature thermopower and T_c does not hold in the BSLCO system.
Instead, comparison of the temperature-dependent R_H data with other cuprate
systems is used as a tool to identify the actual p value. To justify this
approach, we compare normalized R_H(T) data of BSLCO, La_{2-x}Sr_{x}CuO_{4}
(LSCO), YBa_{2}Cu_{3}O_{y}, and Tl_{2}Ba_{2}CuO_{6+\delta}, and demonstrate
that the R_H(T) data of the LSCO system can be used as a template for the
estimation of p. The resulting phase diagram of p vs T_c for BSLCO suggests
that T_c is anomalously suppressed in the underdoped samples, becoming zero at
around p ~ 0.10, while the optimum T_c is achieved at p ~ 0.16 as expected.Comment: 4 pages including 5 figures, accepted for publication in Phys. Rev.
B, Rapid Communication
Development Of L-band High Power Rf Source For The Japanese hadron Project proton Linear Accelerator
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