907 research outputs found
The nature of GRB-selected submillimeter galaxies: hot and young
We present detailed fits of the spectral energy distributions (SEDs) of four
submillimeter (submm) galaxies selected by the presence of a gamma-ray burst
(GRB) event (GRBs 980703, 000210, 000418 and 010222). These faint ~3 mJy submm
emitters at redshift ~1 are characterized by an unusual combination of long-
and short-wavelength properties, namely enhanced submm and/or radio emission
combined with optical faintness and blue colors. We exclude an active galactic
nucleus as the source of long-wavelength emission. From the SED fits we
conclude that the four galaxies are young (ages <2 Gyr), highly starforming
(star formation rates ~150 MSun/yr), low-mass (stellar masses ~10^10 MSun) and
dusty (dust masses ~3x10^8 MSun). Their high dust temperatures (Td>45 K)
indicate that GRB host galaxies are hotter, younger, and less massive
counterparts to submm-selected galaxies detected so far. Future facilities like
Herschel, JCMT/SCUBA-2 and ALMA will test this hypothesis enabling measurement
of dust temperatures of fainter GRB-selected galaxies.Comment: 9 pages, 2 figures, submitted to ApJ, for SED templates, see
http://archive.dark-cosmology.dk
Phylogenetic Approach to the Study of Triatomines (Triatominae, Heteroptera) = Abordagem filogenética em Triatomíneos (Triatominae, Heteroptera)
Abstracts
Triatomines are insects belonging to the Hemiptera order, Heteroptera suborder, Reduviidae family and Triatominae subfamily. All members of this subfamily are hematophagous. Triatomines evolved from Reduviidae predators and they are probably polyphyletic in origin. The combination of anatomical, physiological and ethological factors observed in this group, as well as the plesiomorphic and apomorphic characters that differentiate the five tribes and fourteen triatomine genera reinforce the polyphiletic hypotesis. However if we consider the five groups of triatomines, the Rhodniini, Cavernicolini, Bolboderini, Linshcosteini and Alberproseniini tribes constitute monophyletic groups, while the Triatomini tribe is considered polyphyletic. The New World is the center of triatomine diversity and seems to be the point of group origin. Of approximately 137 triatomine species, 105 are only found in the Americas. It is now considered that triatomines represent a polyphyletic group defined according to their convergent apomorphic hematophagous characters, which have appeared several times in Reduviidae. This study revises the phylogeny of these vectors of Chagas\u27 disease, covering such topics as the origin of hematophagy in triatomines and ancestral proposal for the group.
Os triatomíneos são insetos pertencentes à ordem Hemiptera, subordem Heteroptera, família Reduviidae e subfamília Triatominae. Todos os membros desta subfamília são hematófagos. Os triatomíneos surgiram a partir de reduvídeos predadores e provavelmente têm origem polifilética. A combinação dos fatores anatômicos, fisiológicos e etológicos presentes no grupo, bem como os caracteres plésio e apomórficos que diferenciam as cinco tribos e os quatorze gêneros de triatomíneos reforçam a hipótese polifilética. As tribos Rhodniini, Cavernicolini, Bolboderini, Linshcosteini e Alberproseniini constituem grupos monofiléticos, per si, enquanto a tribo Triatomini é considerada polifilética. O Novo Mundo é claramente o centro de diversidade dos triatomíneos e possivelmente é a região de sua origem. Entre as aproximadamente 129 espécies desses insetos, 105 ocorrem somente nas Américas. Atualmente, os triatomíneos são considerados um grupo polifilético, definido com base em seus caracteres apomórficos convergentes relacionados à hematofagia. Acredita-se que este hábito alimentar tenha surgido várias vezes nos Reduviidae durante sua evolução. O presente trabalho faz uma revisão sobre a filogenia destes vetores da Doença de Chagas, aborda tópicos como a origem da hematofagia nos triatomíneos e ancestralidade proposta para o grupo
New Higgs signals induced by mirror fermion mixing effects
We study the conditions under which flavor violation arises in scalar-fermion
interactions, as a result of the mixing phenomena between the standard model
and exotic fermions. Phenomenological consequences are discussed within the
specific context of a left-right model where these additional fermions have
mirror properties under the new SU(2)_R gauge group.
Bounds on the parameters of the model are obtained from LFV processes; these
results are then used to study the LFV Higgs decays (H --> tau l_j, l_j = e,
mu), which reach branching ratios that could be detected at future colliders.Comment: 12 pages, 2 figures, ReVTex4, graphicx, to be published in Phys. Rev.
Use of segmented polynomials to study the lactation curve of Murrah and their crossed breeds of buffaloes under an extensive production system in the State of Sao Paulo
The objective of this study was to evaluate the use of segmented polynomials, described by the two models quadratic-quadratic (PSQQ) and that with three quadratic segments (PSQQQ), for adjustment of the mean lactation curve of Murrah females and their crosses under a system of extensive production, with once daily milking. Studies of this nature in buffaloes are practically non-existent. Milk production data from twelve herds, including 1280 lactations and 8839 test-day milk weights were analyzed. Test days were spaced at 30-day intervals, during the period from 1995 to 2001. Lactations included in the analysis were based on a minimum of four and a maximum of nine test days. For the PSQQ model, the mean curve reached its “Knot” (junction point between the segments) in the second month of lactation, while for the PSQQ model the “Knots” were estimated to be in the second and fourth months. The parameters of each function were estimated by interactive procedures, using PROC REG of SAS. Criteria used to verify the goodness of fit for each function were: adjusted coefficient of determination (R2A); lack of fit test (LOF); and graphic distribution of residuals and of residual lag. The two models closely described variations in milk production throughout the lactation with the lack of fit tests not significant. The coefficients of determination were practically identical for both models under study (R2A = 91.3%). (Text in Portuguese)
The very red afterglow of GRB 000418 - further evidence for dust extinction in a GRB host galaxy
We report near-infrared and optical follow-up observations of the afterglow
of the Gamma-Ray Burst 000418 starting 2.5 days after the occurrence of the
burst and extending over nearly seven weeks. GRB 000418 represents the second
case for which the afterglow was initially identified by observations in the
near-infrared. During the first 10 days its R-band afterglow was well
characterized by a single power-law decay with a slope of 0.86. However, at
later times the temporal evolution of the afterglow flattens with respect to a
simple power-law decay. Attributing this to an underlying host galaxy we find
its magnitude to be R=23.9 and an intrinsic afterglow decay slope of 1.22. The
afterglow was very red with R-K=4 mag. The observations can be explained by an
adiabatic, spherical fireball solution and a heavy reddening due to dust
extinction in the host galaxy. This supports the picture that (long) bursts are
associated with events in star-forming regions.Comment: Accepted for publication in The Astrophysical Journal. 12 pages;
citations & references updated; minor textual change
Cost-effectiveness of genotype-guided and dual antiplatelet therapies in acute coronary syndrome.
BackgroundThe choice of antiplatelet therapy after acute coronary syndrome (ACS) is complicated: Ticagrelor and prasugrel are novel alternatives to clopidogrel, patients with some genotypes may not respond to clopidogrel, and low-cost generic formulations of clopidogrel are available.ObjectiveTo determine the most cost-effective strategy for dual antiplatelet therapy after percutaneous coronary intervention for ACS.DesignDecision-analytic model.Data sourcesPublished literature, Medicare claims, and life tables.Target populationPatients having percutaneous coronary intervention for ACS.Time horizonLifetime.PerspectiveSocietal.InterventionFive strategies were examined: generic clopidogrel, prasugrel, ticagrelor, and genotyping for polymorphisms of CYP2C19 with carriers of loss-of-function alleles receiving either ticagrelor (genotyping with ticagrelor) or prasugrel (genotyping with prasugrel) and noncarriers receiving clopidogrel.Outcome measuresDirect medical costs, quality-adjusted life years(QALYs), and incremental cost-effectiveness ratios (ICERs).Results of base-case analysisThe clopidogrel strategy produced35 800 per QALY relative to clopidogrel. Genotyping with ticagrelor was more effective than genotyping with prasugrel (52 600 per QALY relative to genotyping with ticagrelor).Results of sensitivity analysisStronger associations between genotype and thrombotic outcomes rendered ticagrelor substantially less cost-effective ($104 800 per QALY). Genotyping with prasugrel was the preferred therapy among patients who could not tolerate ticagrelor.LimitationNo randomized trials have directly compared genotyping strategies or prasugrel with ticagrelor.ConclusionGenotype-guided personalization may improve the cost-effectiveness of prasugrel and ticagrelor after percutaneous coronary intervention for ACS, but ticagrelor for all patients may bean economically reasonable alternative in some settings
A HIGH RESOLUTION TEMPERATURE CLIMATOLOGY FOR THE GREATER ALPINE REGION (GAR)
The Greater Alpine Region (the GAR) covering the area between 4-19°E and 43-50°N and an altitude range between 0 and more than 4000 m asl. offers a challenging climate worth to be studied in any detail. However, it is surprising that up to now no comprehensive Alpine Temperature Climatology covering the whole region is existing. To overcome this deficiency as a first step we want to produce monthly temperature maps for this region in spatial resolution as high as possible. The period under investigation will be 1961-1990. In this paper we will describe the first steps of our initiative as well as the further plans
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Extracellular Vesicles from Fusarium graminearum Contain Protein Effectors Expressed during Infection of Corn.
Fusarium graminearum (Fgr) is a devastating filamentous fungal pathogen that causes diseases in cereals, while producing mycotoxins that are toxic for humans and animals, and render grains unusable. Low efficiency in managing Fgr poses a constant need for identifying novel control mechanisms. Evidence that fungal extracellular vesicles (EVs) from pathogenic yeast have a role in human disease led us to question whether this is also true for fungal plant pathogens. We separated EVs from Fgr and performed a proteomic analysis to determine if EVs carry proteins with potential roles in pathogenesis. We revealed that protein effectors, which are crucial for fungal virulence, were detected in EV preparations and some of them did not contain predicted secretion signals. Furthermore, a transcriptomic analysis of corn (Zea mays) plants infected by Fgr revealed that the genes of some of the effectors were highly expressed in vivo, suggesting that the Fgr EVs are a mechanism for the unconventional secretion of effectors and virulence factors. Our results expand the knowledge on fungal EVs in plant pathogenesis and cross-kingdom communication, and may contribute to the discovery of new antifungals
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