1,473 research outputs found
How should we measure the return on public investment in a VAR?
A new method of empirically computing the macroeconomic returns to public investment is proposed. Pereira's (2000) technique is modified, and a measure which accounts for both public and private investment costs is suggested. An empirical application to US data shows that differences between alternative ways of measuring rates of return are non-trivial - taking into consideration the full investment effort halves estimated returns when partial public costs only are considered.
Whitening of the Quark-Gluon Plasma
Parton-parton collisions do not neutralize local color charges in the
quark-gluon plasma as they only redistribute the charges among momentum modes.
We discuss color diffusion and color conductivity as the processes responsible
for the neutralization of the plasma. For this purpose, we first compute the
conductivity and diffusion coefficients in the plasma that is significantly
colorful. Then, the time evolution of the color density due to the conductivity
and diffusion is studied. The conductivity is shown to be much more efficient
than the diffusion in neutralizing the plasma at the scale longer than the
screening length. Estimates of the characteristic time scales, which are based
on close to global equilibrium computations, suggest that first the plasma
becomes white and then the momentum degrees of freedom thermalize.Comment: 9 pages, revised, to appear in Phys. Rev.
How should we measure the return on public investment in a VAR
Pereira’s (2000) method of computing the return on public investment in a VAR is extended. A new return measure which accounts for public and private costs is proposed. An application to US data shows non-trivial differences between alternative return rates.Public investment;rate of return;VAR.
How should we monitor men receiving testosterone replacement therapy?
Monitor hematocrit and bone mineral density (BMD) (strength of recommendation [SOR]: B, meta-analysis of non−patient-oriented outcomes). Monitoring prostate-specific antigen (PSA), performing prostate digital rectal examination, and observing symptom response to testosterone are also recommended, although direct evidence is lacking (SOR: C, consensus opinion). Monitoring lipid levels is unnecessary (SOR: A, based on several meta-analyses), as is monitoring testosterone levels (SOR C, consensus opinion). Unless the patient is taking oral testosterone, no evidence exists for or against monitoring liver function (SOR: C, consensus opinion)
Hard-Loop Effective Action for Anisotropic Plasmas
We generalize the hard-thermal-loop effective action of the equilibrium
quark-gluon plasma to a non-equilibrium system which is space-time homogeneous
but for which the parton momentum distribution is anisotropic. We show that the
manifestly gauge-invariant Braaten-Pisarski form of the effective action can be
straightforwardly generalized and we verify that it then generates all n-point
functions following from collisionless gauge-covariant transport theory for a
homogeneous anisotropic plasma. On the other hand, the Taylor-Wong form of the
hard-thermal-loop effective action has a more complicated generalization to the
anisotropic case. Already in the simplest case of anisotropic distribution
functions, it involves an additional term that is gauge invariant by itself,
but nontrivial also in the static limit.Comment: 12 pages. Version 3: typo in (15) corrected, note added discussing
metric conventions use
Local equilibrium of the quark-gluon plasma
Within kinetic theory, we look for local equilibrium configurations of the
quark-gluon plasma by maximizing the local entropy. We use the well-established
transport equations in the Vlasov limit, supplemented with the Waldmann-Snider
collision terms. Two different classes of local equilibrium solutions are
found. The first one corresponds to the configurations that comply with the
so-called collisional invariants. The second one is given by the distribution
functions that cancel the collision terms, representing the most probable
binary interactions with soft gluon exchange in the t-channel. The two sets of
solutions agree with each other if we go beyond these dominant processes and
take into account subleading quark-antiquark annihilation/creation and gluon
number non-conserving processes. The local equilibrium state appears to be
colorful, as the color charges are not locally neutralized. Properties of such
an equilibrium state are analyzed. In particular, the related hydrodynamic
equations of a colorful fluid are derived. Possible neutralization processes
are also briefly discussed.Comment: 20 pages; minor changes, to be published in Phys. Rev.
The cyclin-dependent kinase inhibitor p57(Kip2) is epigenetically regulated in carboplatin resistance and results in collateral sensitivity to the CDK inhibitor seliciclib in ovarian cancer
Carboplatin remains a first-line agent in the management of epithelial ovarian cancer (EOC). Unfortunately, platinum-resistant disease ultimately occurs in most patients. Using a novel EOC cell line with acquired resistance to carboplatin: PEO1CarbR, genome-wide micro-array profiling identified the cyclin-dependent kinase inhibitor p57(Kip2) as specifically downregulated in carboplatin resistance. Presently, we describe confirmation of these preliminary data with a variety of approaches
Simulations of extensional flow in microrheometric devices
We present a detailed numerical study of the flow of a Newtonian fluid through microrheometric devices featuring a sudden contraction–expansion. This flow configuration is typically used to generate extensional deformations and high strain rates. The excess pressure drop resulting from the converging and diverging flow is an important dynamic measure to quantify if the device is intended to be used as a microfluidic extensional rheometer. To explore this idea, we examine the effect of the contraction length, aspect ratio and Reynolds number on the flow kinematics and resulting pressure field. Analysis of the computed velocity and pressure fields show that, for typical experimental conditions used in microfluidic devices, the steady flow is highly three-dimensional with open spiraling vortical structures in the stagnant corner regions. The numerical simulations of the local kinematics and global pressure drop are in good agreement with experimental results. The device aspect ratio is shown to have a strong impact on the flow and consequently on the excess pressure drop, which is quantified in terms of the dimensionless Couette and Bagley correction factors. We suggest an approach for calculating the Bagley correction which may be especially appropriate for planar microchannels
X-ray Emission from Nitrogen-Type Wolf-Rayet Stars
We summarize new X-ray detections of four nitrogen-type Wolf-Rayet (WR) stars
obtained in a limited survey aimed at establishing the X-ray properties of WN
stars across their full range of spectral subtypes. None of the detected stars
is so far known to be a close binary. We report Chandra detections of WR 2
(WN2), WR 18 (WN4), and WR 134 (WN6), and an XMM-Newton detection of WR79a
(WN9ha). These observations clearly demonstrate that both WNE and WNL stars are
X-ray sources. We also discuss Chandra archive detections of the WN6h stars WR
20b, WR 24, and WR 136 and ROSAT non-detections of WR 16 (WN8h) and WR 78
(WN7h). The X-ray spectra of all WN detections show prominent emission lines
and an admixture of cool (kT 2 keV) plasma. The hotter
plasma is not predicted by radiative wind shock models and other as yet
unidentified mechanisms are at work. Most stars show X-ray absorption in excess
of that expected from visual extinction (Av), likely due to their strong winds
or cold circumstellar gas. Existing data suggest a falloff in X-ray luminosity
toward later WN7-9 subtypes, which have higher Lbol but slower, denser winds
than WN2-6 stars. This provides a clue that wind properties may be a more
crucial factor in determining emergent X-ray emission levels than bolometric
luminosity.Comment: 42 pages, 5 tables, 10 figure
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