2,135 research outputs found
A line-binned treatment of opacities for the spectra and light curves from neutron star mergers
The electromagnetic observations of GW170817 were able to dramatically
increase our understanding of neutron star mergers beyond what we learned from
gravitational waves alone. These observations provided insight on all aspects
of the merger from the nature of the gamma-ray burst to the characteristics of
the ejected material. The ejecta of neutron star mergers are expected to
produce such electromagnetic transients, called kilonovae or macronovae.
Characteristics of the ejecta include large velocity gradients, relative to
supernovae, and the presence of heavy -process elements, which pose
significant challenges to the accurate calculation of radiative opacities and
radiation transport. For example, these opacities include a dense forest of
bound-bound features arising from near-neutral lanthanide and actinide
elements. Here we investigate the use of fine-structure, line-binned opacities
that preserve the integral of the opacity over frequency. Advantages of this
area-preserving approach over the traditional expansion-opacity formalism
include the ability to pre-calculate opacity tables that are independent of the
type of hydrodynamic expansion and that eliminate the computational expense of
calculating opacities within radiation-transport simulations. Tabular opacities
are generated for all 14 lanthanides as well as a representative actinide
element, uranium. We demonstrate that spectral simulations produced with the
line-binned opacities agree well with results produced with the more accurate
continuous Monte Carlo Sobolev approach, as well as with the commonly used
expansion-opacity formalism. Additional investigations illustrate the
convergence of opacity with respect to the number of included lines, and
elucidate sensitivities to different atomic physics approximations, such as
fully and semi-relativistic approaches.Comment: 27 pages, 22 figures. arXiv admin note: text overlap with
arXiv:1702.0299
Research-based spin-offs targeting the market for technologies: a conceptual model
DINÂMIA, Dezembro de 2009.This paper addresses the commercialisation decisions of research-based spin-off firms, focusing on the case of companies specialising in the production and sale of intellectual property - a model of entrepreneurial behaviour increasingly frequent in science-based fields, and that
research-based spin-offs may be more prone to adopt given their specific characteristics.
Combining insights from the economics of technological change and the strategic management of technology literature, we discuss the conditions that influence spin-offs ability to pursue with this strategy, and advance some theory-driven hypothesis regarding key factors that are likely to determine their choice - nature of knowledge, appropriability conditions, location and degree of control upon complementary assets and institutional setting of origin - and their impact upon firms’ decisions. We add to the still incipient research on this model of behaviour, as well as to recent research on the determinants of the commercialisation strategy of small technologyintensive firms.FC
Salmonella sp. in edible offal (liver and tongue) from pigs slaughtered for consumption
During this study, 120 samples from slaughtered pigs (tongue swabs, n=40; liver swabs, n=40; liver parenchyma, n=40) were collected in a slaughterhouse. Salmonella sp. was isolated using conventional microbiological methods and strains were analyzed using serotyping, antimicrobial susceptibility testing and macrorestriction profiling (MRP) by Pulse Field Gel Electrophoresis (PFGE), to identify clonal relationships and potential contamination sources
Autologous fat grafting: Harvesting techniques
Autologous fat grafting is widely used for soft-tissue augmentation and replacement in reconstructive and aesthetic surgery providing a biocompatible, natural and inexpensive method. Multiple approaches have been developed in the past years, varying in the location of adipose tissue donor-sites, use of wetting solutions, harvesting, processing and placing techniques. Despite many advances in this subject, the lack of standardization in the protocols and the unpredictability of the resorption of the grafted tissue pose a significant limitation for graft retention and subsequent filling. In this review, we discuss several approaches and methods described over the last years concerning the harvesting of autologous fat grafts. We focus on contents such as the best donor-site, differences between existing harvesting techniques (namely tissue resection, hand aspiration or liposuction techniques), recommended harvesting cannula diameters, pressure application and volume of wetting solution injected prior aspiration. Results and comparisons between methods tend to vary according to the outcome measured, thus posing a limitation to pinpoint the most efficient methods to apply in fat grafting. Additionally, the lack of a standard assay to determine viability or volume augmentation of fat grafting remains another limitation to obtain universally accepted grafting procedures and protocols.This work was supported by FEDER – Fundo Europeu de Desenvolvimento Regional, through NORTE 2020 Programa Operacional Regional do Norte - NORTE-01-0145-FEDER-000012 and Instituto de Investigação e Inovação em Saúde (Projeto Estratégico UID/BIM/04293/2013 )
Composition Effects on Kilonova Spectra and Light Curves: I
The merger of neutron star binaries is believed to eject a wide range of
heavy elements into the universe. By observing the emission from this ejecta,
scientists can probe the ejecta properties (mass, velocity and composition
distributions). The emission (a.k.a. kilonova) is powered by the radioactive
decay of the heavy isotopes produced in the merger and this emission is
reprocessed by atomic opacities to optical and infra-red wavelengths.
Understanding the ejecta properties requires calculating the dependence of this
emission on these opacities. The strong lines in the optical and infra-red in
lanthanide opacities have been shown to significantly alter the light-curves
and spectra in these wavelength bands, arguing that the emission in these
wavelengths can probe the composition of this ejecta. Here we study variations
in the kilonova emission by varying individual lanthanide (and the actinide
uranium) concentrations in the ejecta. The broad forest of lanthanide lines
makes it difficult to determine the exact fraction of individual lanthanides.
Nd is an exception. Its opacities above 1 micron are higher than other
lanthanides and observations of kilonovae can potentially probe increased
abundances of Nd. Similarly, at early times when the ejecta is still hot (first
day), the U opacity is strong in the 0.2-1 micron wavelength range and kilonova
observations may also be able to constrain these abundances
Intrahepatic Cholestasis of Pregnancy: Risk Factor for Neonatal Respiratory Distress Syndrome?
Introdução: A colestase intra-hepática da gravidez está associada a complicações fetais e neonatais graves, incluindo síndrome de dificuldade respiratória. Tem sido recomendada terapêutica materna com ácido ursodesoxicólico e antecipação do parto para reduzir o risco de complicações. Os objetivos
foram determinar a associação entre colestase intra-hepática da gravidez e síndrome de dificuldade respiratória neonatal e avaliar a relação com níveis maternos de ácidos biliares e
procedimentos perinatais.
Metodologia: Estudo caso-controlo incluindo grávidas com colestase intra-hepática da gravidez e respetivos recém-nascidos (grupo colestase), com parto numa maternidade
portuguesa de nível III entre 2006 e 2010. Os controlos foram
emparelhados para idade gestacional e peso ao nascimento (1
caso para 2 controlos).
Resultados: Foram incluídas 42 grávidas com colestase
intra-hepática da gravidez (incidência 0,15%) e 53 recém-
-nascidos. Dez recém-nascidos do grupo colestase (19,2%) e 14 controlos (13,7%) tiveram dificuldade respiratória(p=0,375). A FiO2 máxima foi superior no grupo colestase
(mediana 34,0% vs. 25,0%; p=0,294), mas sem diferença
quanto à ventilação mecânica. A idade gestacional ao diagnóstico de colestase materna foi menor nos recém-nascidos com dificuldade respiratória (mediana 30,5 vs 33,5 semanas;
p=0,024). A taxa de parto desencadeado iatrogenicamente(69,8% vs. 40,6%; p=0,001; OR=3,4), cesariana (66,0% vs 44,3%; p=0,01; OR=2,4) e corticoterapia pré-natal (43,4% vs.
25,5%; p=0,022) foi significativamente maior no grupo colestase.
Não se encontrou relação entre dificuldade respiratória neonatal e níveis maternos de ácidos biliares nem terapêutica materna com ácido ursodesoxicólico. Conclusão: A colestase intra-hepática da gravidez, sobretudo
de início precoce, está tendencialmente associada a síndrome de dificuldade respiratória neonatal. A antecipação do parto
traz riscos adicionais para os recém-nascidos. A corticoterapia pré-natal neste contexto pode ter mascarado a verdadeira incidência de dificuldade respiratória neonatal
Neuropathic pain after breast cancer treatment: characterization and risk factors
Context: Neuropathic pain (NP) may be an important contributor to the morbidity burden of breast cancer.
Objectives: We aimed to quantify the incidence of NP in the first year after diagnosis of breast cancer and to identify its main determinants.
Methods: We performed a prospective cohort study including 506 patients with incident breast cancer, recruited at the Portuguese Institute of Oncology of Porto, and followed for one year; patients with incident NP were additionally evaluated when this condition was diagnosed and after six months, to identify chronic NP.
Results: During the first year, 156 patients were diagnosed with NP (30.8%, 95% CI 27.0–35.0). Anxiety (relative risk [RR] 1.50; 95% CI 1.06–2.13), arm symptoms (RR 1.44; 95% CI 1.02–2.05), cancer Stage III/IV (RR 2.47; 95% CI 1.66–3.66), breast-conserving surgery with axillary lymph node dissection (RR 3.13; 95% CI 1.51–6.48), mastectomy with axillary lymph node dissection (RR 2.52; 95% CI 1.25–5.11), and damaging of the intercostobrachial nerve (RR 2.05; 95% CI 1.25–3.37) were predictors of a higher risk of NP. A total of 97 patients (62.2%, 95% CI 54.4–69.4) diagnosed with NP remained symptomatic after six months.
Conclusion: NP and chronic NP were frequent in this population, being associated with anxiety and arm symptoms before breast cancer treatments and type of surgical management. These results highlight the need for monitoring the occurrence of this neurologic side effect of treatments and to develop strategies for reducing the morbidity burden of breast cancer.The work of F. F. was co-funded by “Fundação para a Ciência e a Tecnologia” (grant number SFRH/BD/92630/2013) and by the “Programa Operacional Capital Humano” (POCH/FSE). Data management activities were supported by the Chair on Pain Medicine of the Faculty of Medicine, University of Porto and by the Grünenthal Foundation—Portugal. The authors declare no conflicts of interests
23 years of ozone episodes in Portugal: photochemical and/or stratospheric intrusion
Ponencia presentada en: XXXII Jornadas Científicas de la AME y el XIII Encuentro Hispano Luso de Meteorología celebrado en Alcobendas (Madrid), del 28 al 30 de mayo de 2012.This work was supported by Fundação para a Ciência e Tecnologia (FCT) that funded the DYNOZONE Project (Ref.º PTDC/CTE -
ATM/105507/2008
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