1,282 research outputs found
Saturation properties of nuclear matter in a relativistic mean field model constrained by quark dynamics
We have built an effective Walecka-type hadronic Lagrangian in which the
hadron masses and the density dependence of the coupling constants are deduced
from the quark dynamics using a Nambu-Jona-Lasinio model. The parameters of
this Nambu-Jona-Lasinio model have been determined using the meson properties
in the vacuum but also in the medium through the omega meson mass in nuclei
measured by the TAPS collaboration. Realistic properties of nuclear matter have
been obtained.Comment: 4 pages, 1 figure, to appear in the Proceedings of "Quark Confinement
and the Hadron Spectrum VII
Conformally related massless fields in dS, AdS and Minkowski spaces
In this paper we write down the equation for a scalar conformally coupled
field simultaneously for de Sitter (dS), anti-de Sitter (AdS) and Minkowski
spacetime in d-dimensions. The curvature dependence appears in a very simple
way through a conformal factor. As a consequence the process of curvature free
limit, including wave functions limit and two-points functions, turns to be a
straightforward issue. We determine a set of modes, that we call de Sitter
plane waves, which become ordinary plane waves when the curvature vanishes.Comment: 7 pages, 1 figur
Geminivirus C2 protein represses genes involved in sulphur assimilation and this effect can be counteracted by jasmonate treatment
Geminiviruses are plant viruses that infect a broad range of crops and cause extensive losses worldwide, having an important economic impact. C2, a multifunctional pathogenicity factor encoded by geminiviruses, has been recently shown to suppress the responses to jasmonates in the host plant, which might at least partially explain its well-established role in pathogenicity. Sulphur is one of the essential macro-elements for plant life, and is considered to have a role in plant defence, in a phenomenon named sulphur-induced resistance (SIR) or sulphur-enhanced defence (SED). In this work, we show that geminivirus C2 protein represses the expression of genes involved in the sulphur assimilation pathway in Arabidopsis, but, interestingly, this effect can be neutralized by exogenous jasmonate treatment. These preliminary results may raise the idea that geminiviruses might be affecting sulphur metabolism, and maybe counteracting SIR/SED, through the manipulation of the jasmonate signalling pathway, which would define a novel strategy in plant-virus interactions and may unveil SIR/SED as an important player in the plant defence against viruses.Ministerio de Ciencia y InnovaciĂłn/FEDER AGL2007-66062-C02-02/AGR AGL2010-22287-CO2European Regional Development Fund (ERDF) BIO2010-15201Junta de AndalucĂa BIOÂ27
Birds from sima del elefante, atapuerca, spain: Palaeoecological implications in the oldest human bearing levels of the iberian peninsula
Palaeoenvironmental reconstruction of Early Pleistocene sites has a particular interest as it sheds light on how the arriving of the first Europeans occurred, as well as on the nature of the relation between these humans and the ecosystems. Bird remains are useful tools for this purpose, because they are commonly represented in the assemblages and most taxa still exist, allowing a direct comparison between past and extant birds associations. Here we analyse the bird remains from the Early Pleistocene levels of the Sima del Elefante site (1.1 to 1.5 million years old). Almost 10.000 remains belonging to at least 26 different taxa have been included. The assemblage is dominated by corvids and has a mixed origin, with cave-dwelling taxa dying in the cave and other taxa being accumulated by predators. The Sima del Elefante avian assemblage provides the oldest record of several taxa in the Iberian Peninsula (Haliaeetus albicilla, Corvus pliocaenus). Besides, here we report the oldest evidence of Imperial Eagle in the Iberian Peninsula, prior to the separation of the oriental and Iberian populations. The assemblage composition suggests that open environmental conditions were dominant, with minor presence of woodlands and water bodies, which is congruent with some previous approaches by other proxies. The first humans occupying the Iberian Peninsula inhabited under Mediterranean climate conditions, which gradually deteriorated, as reflected by the avian turnover recorded at the middle Pleistocene Atapuerca assemblages. © 2021 Universita degli Studi di Milano. All rights reserved
Developing Controlled Conductive Boundaries for JWST Cryogenic Testing
In 2017, the James Webb Space Telescope (JWST) underwent functional testing and optical metrology verification of the combined Optical Telescope Element and Integrated Science Instrument Module (OTIS) under cryogenic vacuum conditions in Chamber A at the Johnson Space Center. Maintaining flight-like thermal boundary conditions was a critical requirement for optical testing and required unique and challenging Ground Support Equipment (GSE) design solutions. Two such GSE systems, the Integrated Science Instrument Module (ISIM) Precool Straps and the Hardpoint Struts were direct conduction interfaces to the flight hardware. Hardware safety during cooldown required detailed design of their conductivity, and thermal balance testing required "zero-Q" (0-Q) heater implementation to bring the heat flow to zero, thereby cutting off these non-flight conductive links after operating temperatures were achieved. This paper describes the design considerations and approach implemented to achieve the required flight hardware cool down and return to ambient conditions, ensure flight hardware safety, and minimize the non-flight-like heat flows to or from the observatory during cryo-stable testing
Conformal use of retarded Green's functions for the Maxwell field in de Sitter space
We propose a new propagation formula for the Maxwell field in de Sitter space
which exploit the conformal invariance of this field together with a conformal
gauge condition. This formula allows to determine the classical electromagnetic
field in the de Sitter space from given currents and initial data. It only uses
the Green's function of the massless Minkowskian scalar field. This leads to
drastic simplifications in practical calculations. We apply this formula to the
classical problem of the two charges of opposite signs at rest at the North and
South Poles of the de Sitter space.Comment: 19 pages, 4 figures, Revte
Cutaneous metastases from cholangiocarcinoma following percutaneous transhepatic biliary drainage: Case report and literature review
AbstractPercutaneous transhepatic biliary drainage (PTBD) is commonly used in the management of cholangiocarcioma. Major and minor complications of PTBD such as cholangitis, haemorrhage and catheter dislocation are well documented. A lesser reported complication are cutaneous metastases following PTBD for cholangiocarcinoma.We report a case of a 79 year old man who presented with right upper quadrant pain, jaundice and weight loss, with dilated intra-hepatic bile ducts on imaging. The cytology results from a sample taken during endoscopic retrograde cholangiopancreatography were highly suspicious of cholangiocarcioma. A PTBD was subsequently performed and bilateral metal biliary stents were placed without external drainage. Five months after the PTBD he was found to have a hard nodule under the PTBD puncture site. The nodule was excised and the histology confirmed a cholangiocarcinoma metastasis.A review of the literature identified twelve cases of cutaneous metastases from cholangiocarcinoma, following PTBD. In addition, tumour seeding along the catheter tract following PTBD, with metastatic deposits on the abdominal wall, peritoneoum, chest wall, pleural space, and liver parenchyma have also been reported.Health care professionals should be aware of this rare complication and offer appropriate management options to patients
Saturation properties of nuclear matter in a relativistic mean field model constrained by the quark dynamics
We have built an effective Walecka-type hadronic Lagrangian in which the
hadron masses and the density dependence of the coupling constants are deduced
from the quark dynamics using a Nambu-Jona-Lasinio model. In order to stabilize
nuclear matter an eight-quark term has been included. The parameters of this
Nambu-Jona-Lasinio model have been determined using the meson properties in the
vacuum but also in the medium through the omega meson mass in nuclei measured
by the TAPS collaboration. Realistic properties of nuclear matter have been
obtained.Comment: 14 pages, 2 figures, submitted to Nuclear Physics
De Sitter Waves and the Zero Curvature Limit
We show that a particular set of global modes for the massive de Sitter
scalar field (the de Sitter waves) allows to manage the group representations
and the Fourier transform in the flat (Minkowskian) limit. This is in
opposition to the usual acceptance based on a previous result, suggesting the
appearance of negative energy in the limit process. This method also confirms
that the Euclidean vacuum, in de Sitter spacetime, has to be preferred as far
as one wishes to recover ordinary QFT in the flat limit.Comment: 9 pages, latex no figure, to appear in Phys. Rev.
Oregon Medicaid Expenditures after the 2014 Affordable Care Act Medicaid Expansion: Over-time Differences among New, Returning, and Continuously Insured Enrollees
Background—There is interest in assessing healthcare utilization and expenditures among new Medicaid enrollees after the 2014 Medicaid expansion. Recent studies have not differentiated between newly enrolled individuals and those returning after coverage gaps.
Objectives—To assess healthcare expenditures among Medicaid enrollees in the 24 months after Oregon’s 2014 Medicaid expansions and examine whether expenditure patterns were different among the newly, returning, and continuously insured.
Research Design—Retrospective cohort study using inverse-propensity weights to adjust for differences between groups.
Subjects—Oregon adult Medicaid beneficiaries insured continuously from 2014-2015 who were either newly, returning, or continuously insured.
Measures—Monthly expenditures for inpatient care, prescription drugs, total outpatient care, and subdivisions of outpatient care: emergency department (ED), dental, mental and behavioral health (MBH), primary care (PC), and specialist care.
Results—After initial increases, newly and returning insured outpatient expenditures dropped below continuously insured. Expenditures for ED and dental services among the returning insured remained higher than among the newly insured. Newly insured MBH, PC, and specialist expenditures plateaued higher than returning insured. Prescription drug expenditures increased over time for all groups, with continuously insured highest and returning insured lowest. All groups had similar inpatient expenditures over 24 months post-Medicaid expansion.
Conclusions—Our findings reveal that outpatient expenditures for new non-pregnant, non-dual-eligible Oregon Medicaid recipients stabilized over time after meeting pent-up demand, and prior insurance history affected the mix of services that individuals received. Policy evaluations should consider expenditures over at least 24 months and should account for enrollees’ prior insurance histories
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