4,859 research outputs found
The first 8-13 micron spectra of globular cluster red giants: circumstellar silicate dust grains in 47 Tucanae (NGC 104)
We present 8-13 micron spectra of eight red giants in the globular cluster 47
Tucanae (NGC 104), obtained at the European Southern Observatory 3.6m
telescope. These are the first mid-infrared spectra of metal-poor, low-mass
stars. The spectrum of at least one of these, namely the extremely red,
large-amplitude variable V1, shows direct evidence of circumstellar grains made
of amorphous silicate.Comment: Accepted for publication in Astronomy and Astrophysics, 5 page
Building a collection of phage-derived capsular depolymerases to tackle relevant A. baumannii capsular types
A. baumannii is the major cause of nosocomial and drug-resistant infections, its capsule representing
a major virulence factor. This pathogen evolved to display a high variety of capsular types for
evading host defenses and protecting themselves from predators. Some bacteriophages also
evolved to produce capsular depolymerases, enzymes that specifically bind and degrade the bacterial
capsules, allowing these phages to overcome this barrier and proceed with the infection.
In this study, 94 carbapenem-resistant A. baumannii clinical isolates (Northern region of Portugal,
2005-2012), were screened for their resistance genes by PCR. Genes Oxa-23, Imp-like and Oxa-24
were present in 76%, 20% and 16% of the isolates, respectively. Based on their resistance gene profile,
the genomes of 23 strains were sequenced. Using in silico typing with Kaptive, we found 4
prevalent capsular types, namely, KL2 (39%), KL7 (30%), KL9 (4%) and KL120 (26%).
Aiming at implementing an effective depolymerase-based anti-virulence strategy to control A. baumannii
infections, we isolated novel capsular depolymerases from lytic and prophages, ending with
an in-house collection of enzymes targeting 10 capsular types (KL1, KL2, KL9, KL19, KL30, KL32,
KL38, KL44, KL45, KL67). Experiments using a human serum model proved that all capsular depolymerases
can effectively sensitize A. baumannii to the host complement killing activity, that otherwise
were resistant. Therefore, capsular depolymerases have demonstrated to be a very powerful
anti-virulence weapon and an emerging solution to treat A.baumannii-related infections.
As a result, the collection of capsular depolymerases available was expanded to 17 K-specific depolymerases,
advancing the prospects of application of these enzymes to control A. baumannii
infections.info:eu-repo/semantics/publishedVersio
A Spitzer c2d Legacy Survey to Identify and Characterize Disks with Inner Dust Holes
Understanding how disks dissipate is essential to studies of planet
formation. However, identifying exactly how dust and gas dissipates is
complicated due to difficulty in finding objects clearly in the transition of
losing their surrounding material. We use Spitzer IRS spectra to examine 35
photometrically-selected candidate cold disks (disks with large inner dust
holes). The infrared spectra are supplemented with optical spectra to determine
stellar and accretion properties and 1.3mm photometry to measure disk masses.
Based on detailed SED modeling, we identify 15 new cold disks. The remaining 20
objects have IRS spectra that are consistent with disks without holes, disks
that are observed close to edge-on, or stars with background emission. Based on
these results, we determine reliable criteria for identifying disks with inner
holes from Spitzer photometry and examine criteria already in the literature.
Applying these criteria to the c2d surveyed star-forming regions gives a
frequency of such objects of at least 4% and most likely of order 12% of the
YSO population identified by Spitzer.
We also examine the properties of these new cold disks in combination with
cold disks from the literature. Hole sizes in this sample are generally smaller
than for previously discovered disks and reflect a distribution in better
agreement with exoplanet orbit radii. We find correlations between hole size
and both disk and stellar masses. Silicate features, including crystalline
features, are present in the overwhelming majority of the sample although 10
micron feature strength above the continuum declines for holes with radii
larger than ~7 AU. In contrast, PAHs are only detected in 2 out of 15 sources.
Only a quarter of the cold disk sample shows no signs of accretion, making it
unlikely that photoevaporation is the dominant hole forming process in most
cases.Comment: 24 pages, 18 figures and 8 tables. Fixed a typo in Table
On the Evolution of Dust Mineralogy, From Protoplanetary Disks to Planetary Systems
Mineralogical studies of silicate features emitted by dust grains in
protoplanetary disks and Solar System bodies can shed light on the progress of
planet formation. The significant fraction of crystalline material in comets,
chondritic meteorites and interplanetary dust particles indicates a
modification of the almost completely amorphous ISM dust from which they
formed. The production of crystalline silicates thus must happen in
protoplanetary disks, where dust evolves to build planets and planetesimals.
Different scenarios have been proposed, but it is still unclear how and when
this happens. This paper presents dust grain mineralogy of a complete sample of
protoplanetary disks in the young Serpens cluster. These results are compared
to those in the young Taurus region and to sources that have retained their
protoplanetary disks in the older Upper Scorpius and Eta Chamaeleontis stellar
clusters, using the same analysis technique for all samples. This comparison
allows an investigation of the grain mineralogy evolution with time for a total
sample of 139 disks. The mean cluster age and disk fraction are used as
indicators of the evolutionary stage of the different populations. Our results
show that the disks in the different regions have similar distributions of mean
grain sizes and crystallinity fractions (~10-20%) despite the spread in mean
ages. Furthermore, there is no evidence of preferential grain sizes for any
given disk geometry, nor for the mean cluster crystallinity fraction to
increase with mean age in the 1-8 Myr range. The main implication is that a
modest level of crystallinity is established in the disk surface early on (< 1
Myr), reaching a equilibrium that is independent of what may be happening in
the disk midplane. These results are discussed in the context of planet
formation, in comparison with mineralogical results from small bodies in our
Solar System. [Abridged]Comment: Accepted for publication in the Astrophysical Journa
Hábitos alimentares e risco de doenças cardiovasculares em universitários
Modelo de estudo: Pesquisa descritiva, observacional, transversal. Objetivo: Descrever qualitativamente a frequĂŞncia de ingestĂŁo de determinados alimentos, considerados de risco e de proteção para doenças cardiovasculares (DCV), alĂ©m de determinar o Escore de Risco de Framingham (ERF) em indivĂduos supostamente saudáveis, estudantes de graduação de uma universidade pĂşblica brasileira. Metodologia: Participaram 97 estudantes, 45 homens e 52 mulheres, na faixa etária de 18 a 25 anos. ApĂłs assinatura do Termo de Consentimento Livre e Esclarecido (TCLE), aprovado pelo ComitĂŞ de Ética em Pesquisa, os estudantes preencheram um questionário com os dados da pesquisa. Foram estudados alimentos classificados como de risco e de proteção, conforme sua composição quĂmica avaliada por tabelas de alimentos. O teste Qui-quadrado fui utilizado quando as frequĂŞncias esperadas foram iguais ou superiores a 5. Para os demais parâmetros foi utilizado o teste exato de Fischer. Resultados: Entre os alimentos protetores destacou-se a ingestĂŁo diária de legumes (33%), verduras (22%) e frutas (17%) e entre os de risco estĂŁo a ingestĂŁo diária de cafĂ©/chás com açúcar (39%), maionese/ margarina/manteiga (34%) e doces (14%). Houve variação de consumo conforme o sexo, para as frequĂŞncias de 0,1, 2 e 4 vezes por semana para os alimentos: farinha de milho/mandioca, biscoito maisena/caseiro/água e sal, aveia, frango com pele. Houve variação significativa de consumo diário entre os sexos para os alimentos: frutas, doces, maionese/margarina/manteiga, biscoito maisena/caseiro/ água e sal. Conclusões: Este estudo demonstrou que os estudantes universitários apresentaram uma maior frequĂŞncia diária de ingestĂŁo de alimentos considerados de proteção para DCV do que alimentos de risco. Em adição, o ERF calculado demonstrou baixo risco de desenvolvimento de DCV nos indivĂduos avaliados.Study Design: Descriptive, observational, cross-sectional. Aims: The aims of this study were to qualitatively describe the frequency of eating certain foods, as risk and protective for cardiovascular disease (CVD), and determine the Framingham Risk Score (FRS) in supposedly healthy individuals, graduate students from a Brazilian public university. Methodology: Participants were 97 students, 45 males and 52 females, 18-25 years. After signing the consent form, approved by the Ethics Committee on Research, students completed a questionnaire survey data. We studied food classified as risk and protection, as assessed by its chemical composition tables. The Chi-square test was used when the expected frequencies greater than or equal to 5. For other parameters we used the Fisher exact test. Results: Among the foods considered protective stood out the daily intake of vegetables (33%), greens (22%) and fruit (17%). Among the foods considered at risk are the daily intake of coffee / tea with sugar (39%), mayonnaise / margarine / butter (34%) and sweets (14%). There was variation in consumption according to sex, for the frequencies of 0, 1, 2 and 4 times a week for food: corn flour / cassava, cornstarch cookie /homemade cookie / water and salt cookie, oats, chicken with skin. There was significant variation in daily consumption between the sexes for food: fruit, sweets, mayonnaise / margarine / butter, cornstarch cookie / homemade cookie / water and salt cookie. Conclusion: This study showed that college students presented higher frequency of daily intake of foods considered protective for CVD than risk food. In addition, the calculated FRS demonstrated low risk of developing CVD in studied individuals
Optimizing the fast Rydberg quantum gate
The fast phase gate scheme, in which the qubits are atoms confined in sites
of an optical lattice, and gate operations are mediated by excitation of
Rydberg states, was proposed by Jaksch et al. Phys. Rev. Lett. 85, 2208 (2000).
A potential source of decoherence in this system derives from motional heating,
which occurs if the ground and Rydberg states of the atom move in different
optical lattice potentials. We propose to minimize this effect by choosing the
lattice photon frequency \omega so that the ground and Rydberg states have the
same frequency-dependent polarizability \alpha(omega). The results are
presented for the case of Rb.Comment: 5 pages, submitted to PR
Identification of QTLs for grain yield and other traits in tropical maize under high and low soil-nitrogen environments.
Article purchased; Published online: 03 Nov 2017Low soil Nitrogen (low-N) is one of the most important abiotic stresses responsible for significant yield losses in maize (Zea mays. L.). The development and commercialization of low N tolerant genotypes can contribute to improved food security in developing countries. However, selection for low N tolerance is difficult because it is a complex trait with strong interaction between genotypes and environments. Marker assisted breeding holds great promise for improving such complex traits more efficiently in less time, but requires markers associated with the trait of interest. In this study, 150 BC2F1 families of CML 444 x CML 494 were evaluated at two location for two consecutive seasons to identify SNP markers associated with quantitative trait loci (QTLs) for yield and other agronomic traits under low- and high-N environments. A total of 13 QTLs were identified with 158 SNP markers, of which nine and four QTLs were detected under low- and high-N environments, respectively. Five QTLs one each for grain yield (qgy-1), days to silking (qdts-1) and anthesis- silking interval (qasi-6), and two for stay green characteristic (qsg-1 and qsg-4) were close to their adjacent markers, with an interval of 0.7 to 5.2 cM between them and explained phenotypic variance of 9 to 21%. These QTLs would be invaluable for rapid introgression of genomic regions into maize populations using marker assisted selection (MAS) approaches. However, further validation of these QTLs is needed before use in MAS
Comparison of two peptide radiotracers for prostate carcinoma targeting
OBJECTIVES: Scintigraphy is generally not the first choice treatment for prostate cancer, although successful studies using bombesin analog radiopeptides have been performed. Recently, a novel peptide obtained using a phage display library demonstrated an affinity for prostate tumor cells. The aim of this study was to compare the use of a bombesin analog to that of a phage display library peptide (DUP-1) radiolabeled with technetium-99m for the treatment of prostate carcinoma. The peptides were first conjugated to S-acetyl-MAG3 with a 6-carbon spacer, namely aminohexanoic acid. METHODS: The technetium-99m labeling required a sodium tartrate buffer. Radiochemical evaluation was performed using ITLC and was confirmed by high-performance liquid chromatography. The coefficient partition was determined, and in vitro studies were performed using human prostate tumor cells. Biodistribution was evaluated in healthy animals at various time points and also in mice bearing tumors. RESULTS: The radiochemical purity of both radiotracers was greater than 95%. The DUP-1 tracer was more hydrophilic (log P = -2.41) than the bombesin tracer (log P = -0.39). The biodistribution evaluation confirmed this hydrophilicity by revealing the greater kidney uptake of DUP-1. The bombesin concentration in the pancreas was greater than that of DUP-1 due to specific gastrin-releasing peptide receptors. Bombesin internalization occurred for 78.32% of the total binding in tumor cells. The DUP-1 tracer showed very low binding to tumor cells during the in vitro evaluation, although tumor uptake for both tracers was similar. The tumors were primarily blocked by DUP1 and the bombesin radiotracer primarily targeted the pancreas. CONCLUSION: Further studies with the radiolabeled DUP-1 peptide are recommended. With further structural changes, this molecule could become an efficient alternative tracer for prostate tumor diagnosis
Postingestive Modulation of Food Seeking Depends on Vagus-Mediated Dopamine Neuron Activity
Postingestive nutrient sensing can induce food preferences. However, much less is known about the ability of postingestive signals to modulate food-seeking behaviors. Here we report a causal connection between postingestive sucrose sensing and vagus-mediated dopamine neuron activity in the ventral tegmental area (VTA), supporting food seeking. The activity of VTA dopamine neurons increases significantly after administration of intragastric sucrose, and deletion of the NMDA receptor in these neurons, which affects bursting and plasticity, abolishes lever pressing for postingestive sucrose delivery. Furthermore, lesions of the hepatic branch of the vagus nerve significantly impair postingestive-dependent VTA dopamine neuron activity and food seeking, whereas optogenetic stimulation of left vagus nerve neurons significantly increases VTA dopamine neuron activity. These data establish a necessary role of vagus-mediated dopamine neuron activity in postingestive-dependent food seeking, which is independent of taste signaling.info:eu-repo/semantics/publishedVersio
Prime Focus Spectrograph - Subaru's future -
The Prime Focus Spectrograph (PFS) of the Subaru Measurement of Images and
Redshifts (SuMIRe) project has been endorsed by Japanese community as one of
the main future instruments of the Subaru 8.2-meter telescope at Mauna Kea,
Hawaii. This optical/near-infrared multi-fiber spectrograph targets cosmology
with galaxy surveys, Galactic archaeology, and studies of galaxy/AGN evolution.
Taking advantage of Subaru's wide field of view, which is further extended with
the recently completed Wide Field Corrector, PFS will enable us to carry out
multi-fiber spectroscopy of 2400 targets within 1.3 degree diameter. A
microlens is attached at each fiber entrance for F-ratio transformation into a
larger one so that difficulties of spectrograph design are eased. Fibers are
accurately placed onto target positions by positioners, each of which consists
of two stages of piezo-electric rotary motors, through iterations by using
back-illuminated fiber position measurements with a wide-field metrology
camera. Fibers then carry light to a set of four identical fast-Schmidt
spectrographs with three color arms each: the wavelength ranges from 0.38
{\mu}m to 1.3 {\mu}m will be simultaneously observed with an average resolving
power of 3000. Before and during the era of extremely large telescopes, PFS
will provide the unique capability of obtaining spectra of 2400
cosmological/astrophysical targets simultaneously with an 8-10 meter class
telescope. The PFS collaboration, led by IPMU, consists of USP/LNA in Brazil,
Caltech/JPL, Princeton, & JHU in USA, LAM in France, ASIAA in Taiwan, and
NAOJ/Subaru.Comment: 13 pages, 11 figures, submitted to "Ground-based and Airborne
Instrumentation for Astronomy IV, Ian S. McLean, Suzanne K. Ramsay, Hideki
Takami, Editors, Proc. SPIE 8446 (2012)
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