312 research outputs found
Deconfinement and chiral restoration in nonlocal SU(3) chiral quark models
We study the features of nonlocal SU(3) chiral quark models with wave
function renormalization. Model parameters are determined from meson
phenomenology, considering different nonlocal form factor shapes. In this
context we analyze the characteristics of the deconfinement and chiral
restoration transitions at finite temperature, introducing the couplings of
fermions to the Polyakov loop. We analyze the results obtained for various
thermodynamical quantities considering different Polyakov loop potentials and
nonlocal form factors, in comparison with data obtained from lattice QCD
calculations.Comment: 25 pages, 5 figures. Discussion of results enlarged, figures
modified, references added. Version to appear in Physical Review
Generalized Ginzburg-Landau approach to inhomogeneous phases in nonlocal chiral quark models
We analyze the presence of inhomogeneous phases in the QCD phase diagram
within the framework of nonlocal chiral quark models. We concentrate in
particular in the positions of the tricritical (TCP) and Lifshitz (LP) points,
which are studied in a general context using a generalized Ginzburg-Landau
approach. We find that for all the phenomenologically acceptable model
parametrizations considered the TCP is located at a higher temperature and a
lower chemical potential in comparison with the LP. Consequently, these models
seem to favor a scenario in which the onset of the first order transition
between homogeneous phases is not covered by an inhomogeneous, energetically
favored phase.Comment: 9 pages, 1 figure. V2: Two references added, figure modified, minor
changes in the text introduced. Matches version to be published in Physics
Letters
Inhomogeneous phases in nonlocal chiral quark models
The presence of inhomogeneous phases in the QCD phase diagram is analyzed
within chiral quark models that include nonlocal interactions. We work at the
mean field level, assuming that the spatial dependence of scalar and
pseudo-scalar condensates is given by a dual chiral density wave. Phase
diagrams for Gaussian nonlocal form factors are studied in detail and compared
with those obtained within the Nambu-Jona-Lasinio model and quark-meson
approaches.Comment: 14 pages, 3 figure
quark matter phase transitions and critical end point in nonlocal PNJL models
We study the phase diagram of quark matter under the influence
of a strong uniform magnetic field in the framework of a nonlocal extension of
the Polyakov Nambu Jona Lasinio model (PNJL). The existence of a critical end
point (CEP) is found for the whole considered range of the magnetic field (up
to 1 ). We analyze the location of this CEP as a function of the
external field and discuss the presence of inverse magnetic catalysis for
nonzero chemical potentials. Our results show that the temperature of the CEP
decreases with the magnetic field, in contrast to the behavior observed in
local NJL/PNJL models
Gas Concentration Mapping of Arenal Volcano Using AVEMS
The Airborne Volcanic Emissions Mass Spectrometer (AVEMS) System developed by NASA-Kennedy Space Center and deployed in collaboration with the National Center for Advanced Technology (CENAT) and the University of Costa Rica was used for mapping the volcanic plume of Arenal Volcano, the most active volcano in Costa Rica. The measurements were conducted as part of the second CARTA (Costa Rica Airborne Research and Technology Application) mission conducted in March 2005. The CARTA 2005 mission, involving multiple sensors and agencies, consisted of three different planes collecting data over all of Costa Rica. The WB-57F from NASA collected ground data with a digital camera, an analog photogrametric camera (RC-30), a multispectral scanner (MASTER) and a hyperspectral sensor (HYMAP). The second aircraft, a King Air 200 from DoE, mounted with a LIDAR based instrument, targeted topography mapping and forest density measurements. A smaller third aircraft, a Navajo from Costa Rica, integrated with the AVEMS instrument and designed for real-time measurements of air pollutants from both natural and anthropogenic sources, was flown over the volcanoes. The improved AVEMS system is designed for deployment via aircraft, car or hand-transport. The 85 pound system employs a 200 Da quadrupole mass analyzer, has a volume of 92,000 cubic cm, requires 350 W of power at steady state, can operate up to an altitude of 41,000 feet above sea level (-65 C; 50 torr). The system uses on-board gas bottles on-site calibration and is capable of monitoring and quantifying up to 16 gases simultaneously. The in-situ gas data in this work, consisting of helium, carbon dioxide, sulfur dioxide and acetone, was acquired in conjunction of GPS data which was plotted with the ground imagery, topography and remote sensing data collected by the other instruments, allowing the 3 dimensional visualization of the volcanic plume at Arenal Volcano. The modeling of possible scenarios of Arenal s activity and its direct impact on the surrounding populated areas in now possible with the combined set of data, linking in-situ data with remote sensing data. The study also helps in the understanding of pyroclastic flow behavior in case of a major eruption
Charged pseudoscalar and vector meson masses under strong magnetic fields in an extended NJL model
The mass spectrum of and mesons in the presence of a static
uniform magnetic field is studied within a two-flavor NJL-like model.
We improve previous calculations taking into account the effect of Schwinger
phases carried by quark propagators, and using an expansion of meson fields in
terms of the solutions of the corresponding equations of motion for nonzero
. It is shown that the meson polarization functions are diagonal in this
basis. Our numerical results for the meson spectrum are found to
disfavor the existence of a meson condensate induced by the magnetic field. In
the case of the meson, - mixing effects are analyzed for
the meson lowest energy state. The predictions of the model are compared with
available lattice QCD results.Comment: 35 pages, 4 figures. arXiv admin note: text overlap with
arXiv:2205.1592
Review of high-contrast imaging systems for current and future ground- and space-based telescopes I. Coronagraph design methods and optical performance metrics
The Optimal Optical Coronagraph (OOC) Workshop at the Lorentz Center in
September 2017 in Leiden, the Netherlands gathered a diverse group of 25
researchers working on exoplanet instrumentation to stimulate the emergence and
sharing of new ideas. In this first installment of a series of three papers
summarizing the outcomes of the OOC workshop, we present an overview of design
methods and optical performance metrics developed for coronagraph instruments.
The design and optimization of coronagraphs for future telescopes has
progressed rapidly over the past several years in the context of space mission
studies for Exo-C, WFIRST, HabEx, and LUVOIR as well as ground-based
telescopes. Design tools have been developed at several institutions to
optimize a variety of coronagraph mask types. We aim to give a broad overview
of the approaches used, examples of their utility, and provide the optimization
tools to the community. Though it is clear that the basic function of
coronagraphs is to suppress starlight while maintaining light from off-axis
sources, our community lacks a general set of standard performance metrics that
apply to both detecting and characterizing exoplanets. The attendees of the OOC
workshop agreed that it would benefit our community to clearly define
quantities for comparing the performance of coronagraph designs and systems.
Therefore, we also present a set of metrics that may be applied to theoretical
designs, testbeds, and deployed instruments. We show how these quantities may
be used to easily relate the basic properties of the optical instrument to the
detection significance of the given point source in the presence of realistic
noise.Comment: To appear in Proceedings of the SPIE, vol. 1069
Comparing uni-modal and multi-modal therapies for improving writing in acquired dysgraphia after stroke.
Writing therapy studies have been predominantly uni-modal in nature; i.e., their central therapy task has typically been either writing to dictation or copying and recalling words. There has not yet been a study that has compared the effects of a uni-modal to a multi-modal writing therapy in terms of improvements to spelling accuracy. A multiple-case study with eight participants aimed to compare the effects of a uni-modal and a multi-modal therapy on the spelling accuracy of treated and untreated target words at immediate and follow-up assessment points. A cross-over design was used and within each therapy a matched set of words was targeted. These words and a matched control set were assessed before as well as immediately after each therapy and six weeks following therapy. The two approaches did not differ in their effects on spelling accuracy of treated or untreated items or degree of maintenance. All participants made significant improvements on treated and control items; however, not all improvements were maintained at follow-up. The findings suggested that multi-modal therapy did not have an advantage over uni-modal therapy for the participants in this study. Performance differences were instead driven by participant variables
HER-2/neu amplification testing in breast cancer by Multiplex Ligation-dependent Probe Amplification: influence of manual- and laser microdissection
<p>Abstract</p> <p>Background</p> <p>Accurate assessment of HER-2/<it>neu </it>status is crucial for proper prognostic information and to offer direct appropriate treatment for breast cancer patients. Next to immunohistochemistry (IHC) to evaluate HER2 protein overexpression, a second line gene amplification test is generally deemed necessary for cases with equivocal protein expression. Recently, a new PCR based test, called Multiplex Ligation-dependent Probe Amplification (MLPA), was introduced as a simple and quick method to assess HER-2/<it>neu </it>gene amplification status in invasive breast cancer. MLPA was previously shown to correlate well with IHC and <it>in situ </it>hybridization (ISH), but a low tumor percentage in the tissue tested could negatively affect the accuracy of MLPA results.</p> <p>Methods</p> <p>To examine this, MLPA was repeated in 42 patients after serial H&E section guided manual dissection with a scalpel and after laser microdissection of the tumor.</p> <p>Results</p> <p>Both dissection techniques led to higher HER2 gene copy number ratios and thereby made MLPA more quantitative. Concordance between MLPA and ISH improved from 61% to 84% after manual microdissection and to 90% after laser microdissection.</p> <p>Conclusion</p> <p>Manual and laser microdissection similarly increase the dynamic range of MLPA copy number ratios which is a technical advantage. As clinically a dichotomization between normal and amplified suffices and MLPA is relatively unsensitive to tumor content, microdissection before MLPA may not be routinely necessary but may be advisable in case of very low tumor content (≤30%), when MLPA results are equivocal, or when extensive ductal carcinoma <it>in situ </it>is present. Since differences between manual and laser microdissection were small, less time consuming manual microdissection appears to be sufficient.</p
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