2,104 research outputs found
Extremal particles of two-dimensional Coulomb gases and random polynomials on a positive background
We study the outliers for two models which have an interesting connection. On
the one hand, we study a specific class of planar Coulomb gases which are
determinantal. It corresponds to the case where the confining potential is the
logarithmic potential of a radial probability measure. On the other hand, we
study the zeros of random polynomials that appear to be closely related to the
first model. Their behavior far from the origin is shown to depend only on the
decaying properties of the probability measure generating the potential. A
similar feature is observed for their behavior near the origin. Furthermore, in
some cases, the appearance of outliers is observed, and the zeros of random
polynomials and the Coulomb gases are seen to exhibit exactly the same
behavior, which is related to the unweighted Bergman kernel.Comment: 36 pages, 4 figure
Pair Creation of Dilaton Black Holes in Extended Inflation
Dilatonic Charged Nariai instantons mediate the nucleation of black hole
pairs during extended chaotic inflation. Depending on the dilaton and inflaton
fields, the black holes are described by one of two approximations in the
Lorentzian regime. For each case we find Euclidean solutions that satisfy the
no boundary proposal. The complex initial values of the dilaton and inflaton
are determined, and the pair creation rate is calculated from the Euclidean
action. Similar to standard inflation, black holes are abundantly produced near
the Planck boundary, but highly suppressed later on. An unusual feature we find
is that the earlier in inflation that the dilatonic black holes are created,
the more highly charged they can be.Comment: 23 pages, LaTeX, 6 figures; submitted to Phys. Rev.
Broadband radio communications in subway stations and tunnels
Broadband radio communication systems are very important for railway traffic control systems and passengers network services. Nowadays, even though 4G LTE (Long Term Evolution) has deployed for commercial use with excellent results in open areas, it is still lack of knowledge regarding to how such broadband signals propagate inside complex environments with many complex structures that affect propagation such as subway tunnels and stations. For this reason, the aim of the presented measurements in this paper is to model the response of the broadband channel at 1000 MHz and 2450 MHz in the subway environments. These measurements focus on three types of scenarios: subway stations, straight tunnels and a train effect the signal. The results provide detailed information about the propagation channel, which can be useful to develop a broadband propagation model for underground communication systems
Sphingosine-1-phosphate activates chemokine-promoted myeloma cell adhesion and migration involving α4β1 integrin function
51 p.-7 fig.-1 tab.-2 fig.supl.Myeloma cell adhesion dependent on α4β1 integrin is crucial for the progression of multiple myeloma (MM). The α4β1-dependent myeloma cell adhesion is up-regulated by the chemokine CXCL12, and pharmacological blockade of the CXCL12 receptor CXCR4 leads to defective myeloma cell homing to bone marrow (BM). Sphingosine-1-phosphate (S1P) regulates immune cell trafficking upon binding to G-protein-coupled receptors. Here we show that myeloma cells express S1P1, a receptor for S1P. We found that S1P up-regulated the α4β1-mediated myeloma cell adhesion and transendothelial migration stimulated by CXCL12. S1P promoted generation of high-affinity α4β1 that efficiently bound the α4β1 ligand VCAM-1, a finding that was associated with S1P-triggered increase in talin-β1 integrin association. Furthermore, S1P cooperated with CXCL12 for enhancement of α4β1-dependent adhesion strengthening and spreading. CXCL12 and S1P activated the DOCK2-Rac1 pathway, which was required for stimulation of myeloma cell adhesion involving α4β1. Moreover, in vivo analyses indicated that S1P contributes to optimizing the interactions of MM cells with the BM microvasculture and for their lodging inside the bone marrow. The regulation of α4β1-dependent adhesion and migration of myeloma cells by CXCL12-S1P combined activities might have important consequences for myeloma disease progressionThis study was supported by the Ministerio de Ciencia e Innovación (Grant Nos SAF2011-24022 to JT, SAF2009-07035 to AGP, SAF2009-11037 to AH, RD06/0020/0011 to JT and AGP, RD06/0020/0006 to NCG and MG and PI081825 to MG), the Comunidad de Madrid (Grant No. P2010/BMD-2314 to AGP, JT and AH) and the Fundación de Investigación Médica Mutua Madrileña (to AGP and MG). AH was also funded by the FP7-People-2009-RG (Grant No. 246655), a Ramón y Cajal Fellowship (Grant No. RYC-2007-00697) and the Pro-CNIC Foundation.Peer reviewe
Charged Nariai Black Holes With a Dilaton
The Reissner-Nordstrom-de Sitter black holes of standard Einstein-Maxwell
theory with a cosmological constant have no analogue in dilatonic theories with
a Liouville potential. The only exception are the solutions of maximal mass,
the Charged Nariai solutions. We show that the structure of the solution space
of the Dilatonic Charged Nariai black holes is quite different from the
non-dilatonic case. Its dimensionality depends on the exponential coupling
constants of the dilaton. We discuss the possibility of pair creating such
black holes on a suitable background. We find conditions for the existence of
Charged Nariai solutions in theories with general dilaton potentials, and
consider specifically a massive dilaton.Comment: 20 pages, LaTeX, 4 figures, submitted to Phys. Rev.
Measurements and modelling of radio propagation in subway tunnels
The work presented in this article is focused on the RF measurement campaign carried out in several subway tunnels in Metro Madrid (Spain). Most common segments such as straight lines, curves and passing through station as well as other unique scenarios in metropolitan lines were the selected locations during this campaign. Measurements were conducted in tunnels of diverse cross section shapes and taken at three frequency bands: 900 MHz, 2.4GHz and 5.7 GHz for both horizontal and vertical polarization
Patching up the No-Boundary Proposal with virtual Euclidean wormholes
In quantum cosmology, one often considers tunneling phenomena which may have
occurred in the early universe. Processes requiring quantum penetration of a
potential barrier include black hole pair creation and the decay of vacuum
domain walls. Ideally, one calculates the rates for such processes by finding
an instanton, or Euclidean solution of the field equations, which interpolates
between the initial and final states. In practice, however, it has become
customary to calculate such amplitudes using the No-Boundary Proposal of Hartle
and Hawking. A criticism of this method is that it does not use a single path
which interpolates between the initial and final states, but two disjoint
instantons: One divides the probability to create the final state from nothing
by the probability to create the initial state from nothing and decrees the
answer to be the rate of tunneling from the initial to the final state. Here,
we demonstrate the validity of this approach by constructing continuous paths
connecting the ingoing and outgoing data, which may be viewed as perturbations
of the set of disconnected instantons. They are off-shell, but will still
dominate the path integral as they have action arbitrarily close to the
no-boundary action. In this picture, a virtual domain wall, or wormhole, is
created and annihilated in such a way as to interface between the disjoint
instantons. Decay rates calculated using our construction differ from decay
rates calculated using the No-Boundary Proposal only in the prefactor; the
exponent, which usually dominates the result, remains unchanged.Comment: 23 pages REVTeX plus 7 figure
mpMRI-US Fusion-Guided Targeted Cryotherapy in Patients with Primary Localized Prostate Cancer: A Prospective Analysis of Oncological and Functional Outcomes.
Targeted therapy (TT) for prostate cancer (PCa) aims to ablate the malignant lesion with
an adequate margin of safety in order to obtain similar oncological outcomes, but with less toxicity
than radical treatments. The main aim of this study was to evaluate the recurrence rate (RR) in
patients with primary localized PCa undergoing mpMRI/US fusion targeted cryotherapy (FTC). A
secondary objective was to evaluate prostate-specific antigen (PSA) as a predictor of recurrences.
We designed a prospective single-center single-cohort study. Patients with primary localized PCa,
mono or multifocal lesions, PSA 15 ng/mL, and a Gleason score (GS) 4 + 3 undergoing FTC
were enrolled. RR was chosen as the primary outcome. Recurrence was defined as the presence of
clinically significant prostate cancer in the treated areas. PSA values measured at different times were
tested as predictors of recurrence. Continuous variables were assessed with the Bayesian t-test and
categorical assessments with the chix-squared test. Univariate and logistic regression assessment
were used for predictions. A total of 75 cases were included in the study. Ten subjects developed a
recurrence (RR: 15.2%), while fifty-six (84.8%) patients showed a recurrence-free status. A %PSA drop
of 31.5% during the first 12 months after treatment predicted a recurrence with a sensitivity of 53.8%
and a specificity of 79.2%. A PSA drop of 55.3% 12 months after treatment predicted a recurrence
with a sensitivity of 91.7% and a specificity of 51.9%. FTC for primary localized PCa seems to be
associated with a low but not negligible percentage of recurrences. Serum PSA levels may have a role
indicating RR.post-print644 K
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