337 research outputs found
Characterization of dust activity on Mars from MY27 to MY32 by PFS-MEX observations
We present spatial and temporal distributions of dust on Mars from Ls = 331
in MY26 until Ls = 80 in MY33 retrieved from the measurements taken by the
Planetary Fourier Spectrometer (PFS) aboard Mars Express. In agreement with
previous observations, large dust opacity is observed mostly in the southern
hemisphere spring/summer and particularly over regions of higher terrain and
large topographic variation. We present a comparison with dust opacities
obtained from Thermal Emission Spectrometer (TES) - Mars Global Surveyor (MGS)
measurements. We found good consistency between observations of two instruments
during overlapping interval (Ls = 331 in MY26 until Ls = 77 in MY27). We found
a different behavior of the dust opacity with latitude in the various Martian
years (inter-annual variations). A global dust storm occurred in MY28. We
observe a different spatial distribution, a later occurrence and dissipation of
the dust maximum activity in MY28 than in other Martian years. A possible
precursor signal to the global dust storm in MY 28 is observed at Ls = 200 -
235 especially over west Hellas. Heavy dust loads alter atmospheric
temperatures. Due to the absorption of solar radiation and emission of infrared
radiation to space by dust vertically non-uniformly distributed, a strong
heating of high atmospheric levels (40 - 50 km) and cooling below around 30 km
are observed.Comment: in press in Icarus. 47 pages, 15 figure
Androgen deficiency in women
As evidências sugerem que a deficiência androgênica na mulher exibe como principal manifestação clínica a disfunção sexual, especialmente a queda da libido. Entretanto, outros fatores podem também estar implicados na gênese da disfunção sexual, como o relacionamento interpessoal, os estressores sociais, o sedentarismo e o próprio fator masculino. A prevalência da disfunção sexual feminina oscila entre 9 por cento e 43 por cento e recentemente muitos estudos têm mostrado que a reposição com androgênios não só melhora o desempenho sexual, mas também os distúrbios do humor e sintomas vasomotores. Por isso, o profissional de saúde deve sempre incluir no diagnóstico diferencial da disfunção sexual a Síndrome de Deficiência Androgênica, mesmo em mulheres com concentrações séricas normais de estrogênios. O presente artigo tem como objetivo revisar os aspectos práticos da Síndrome de Deficiência Androgênica, enfocando especialmente o diagnóstico e tratamento. Para tanto, nos valemos da análise de 105 artigos publicados em revistas indexadas no PUBMED nos últimos 51 anos (até maio de 2010), incluindo consensos e opiniões de especialistas. Como conclusão, a Síndrome de Deficiência Androgênica na mulher é negligenciada, existindo ainda muitas controvérsias quanto ao seu diagnóstico e terapêutica, especialmente no tocante à escolha do androgênio, a via de administração e o tempo de duração de usoThe evidences suggest that androgen deficiency in women induces sexual dysfunction as the main clinical manifestation, especially reduction of libido. However, other factors may be involved in the disease genesis, such as interpersonal relationships, social stressors, sedentarism and the partner. Prevalence of sexual problems among women ranges from nine to 43% and, recently, many studies have reported that androgens are beneficial not only for the sexual function of women, but for mood disorders and vasomotor symptoms. That is why the physician should include androgen deficiency syndrome as differential diagnosis, even in women with adequate levels of estrogen. Our goal was to present practical aspects of this disease, emphasizing diagnosis and focusing on treatment. This survey covered all the publications indexed in PUBMED in the last 51 years ending May 2010, including consensus and expert opinions; 105 articles were identified. We conclude that the syndrome of androgen deficiency in women is overlooked in clinical practice. There is controversy in literature regarding diagnosis and treatment including choice of drug, route of administration and time of applicatio
Discrete Breathers in a Realistic Coarse-Grained Model of Proteins
We report the results of molecular dynamics simulations of an off-lattice
protein model featuring a physical force-field and amino-acid sequence. We show
that localized modes of nonlinear origin (discrete breathers) emerge naturally
as continuations of a subset of high-frequency normal modes residing at
specific sites dictated by the native fold. In the case of the small
-barrel structure that we consider, localization occurs on the turns
connecting the strands. At high energies, discrete breathers stabilize the
structure by concentrating energy on few sites, while their collapse marks the
onset of large-amplitude fluctuations of the protein. Furthermore, we show how
breathers develop as energy-accumulating centres following perturbations even
at distant locations, thus mediating efficient and irreversible energy
transfers. Remarkably, due to the presence of angular potentials, the breather
induces a local static distortion of the native fold. Altogether, the
combination of this two nonlinear effects may provide a ready means for
remotely controlling local conformational changes in proteins.Comment: Submitted to Physical Biolog
How did the metals in a giant star originate?
The chemical composition of stars with extremely low metal contents (taking
``metals'' to mean all elements other than hydrogen and helium) provides us
with information on the masses of the stars that produced the first metals.
Such a direct connection is not possible, however, if the surface of the star
has been polluted by enriched material, either dredged from the star's interior
or transferred from a companion star. Here we argue that, in the case of
HE0107-5240 (ref. 1), the most iron poor star known, the oxygen abundance could
be a discriminant: a ratio of [O/Fe] exceeding +3.5 would favour a pristine
origin of metals, whereas an [O/Fe] ratio of less than +3 would favour the
pollution hypothesis. Using this criterion, we suggest how the required
information on oxygen abundance might be obtained.Comment: to appear in Nature Brief Communications issue 24 April 200
DISTRIBUIÇÃO ESPACIAL E TEMPORAL DA PRECIPITAÇÃO E TEMPERATURA MÉDIA NA REGIÃO DA SERRA DO CADEADO (PR).
Considerando a carência de estudos sobre as condições climáticas da região da Serra do Cadeado, localizada no setor Norte-Nordeste do estado do Paraná e a influência orográfica direta que esta exerce na dinâmica climática local, este trabalho objetiva fazer uma caracterização da distribuição espacial e temporal das temperaturas e precipitação média acumulada a partir das médias mensais da série histórica das estações climatológicas localizadas no entorno da área, com objetivo de subsidiar novas interpretações e análises sobre a ocorrência da precipitação e da temperatura na área. Os dados indicam que a elevação topográfica e configuração geomorfológica da região influenciam na dinâmica das temperaturas e precipitações médias ao longo do ano
Heavy element abundances in giant stars of the globular clusters M4 and M5
We present a comprehensive abundance analysis of 27 heavy elements in bright
giant stars of the globular clusters M4 and M5 based on high resolution, high
signal-to-noise ratio spectra obtained with the Magellan Clay Telescope. We
confirm and expand upon previous results for these clusters by showing that (1)
all elements heavier than, and including, Si have constant abundances within
each cluster, (2) the elements from Ca to Ni have indistinguishable
compositions in M4 and M5, (3) Si, Cu, Zn, and all s-process elements are
approximately 0.3 dex overabundant in M4 relative to M5, and (4) the r-process
elements Sm, Eu, Gd, and Th are slightly overabundant in M5 relative to M4. The
cluster-to-cluster abundance differences for Cu and Zn are intriguing,
especially in light of their uncertain nucleosynthetic origins. We confirm that
stars other than Type Ia supernovae must produce significant amounts of Cu and
Zn at or below the clusters' metallicities. If intermediate-mass AGB stars or
massive stars are responsible for the Cu and Zn enhancements in M4, the similar
[Rb/Zr] ratios and (preliminary) Mg isotope ratios in both clusters may be
problematic for either scenario. For the elements from Ba to Hf, we assume that
the s- and r-process contributions are scaled versions of the solar s- and
r-process abundances. We quantify the relative fractions of s- and r-process
material for each cluster and show that they provide an excellent fit to the
observed abundances.Comment: Accepted for publication in Ap
Immunity to Error through Misidentification and (Direct and Indirect) Experience Reports
In this contribution, we address the issues concerning the semantic value of Wittgenstein’s subject “I”, as in (i) “I have a toothache”, resulting from the use of predicates that involve first-person knowledge of the mental states to which they refer. As is well-known, these contexts give rise to the phenomenon of ‘immunity to error through misidentification’ (IEM): the utterer of (i) cannot be mistaken as to whether he is the person having a toothache. We provide a series of arguments in favor of a principled distinction between a de facto IEM, grounded in perceptual and proprioceptive judgments, and a de iure IEM, grounded in experience reports whereby the experience wears the experiencer on its sleeve. From this perspective, the no-referent account of subject “I” advocated by Wittgenstein/Anscombe is correct. In fact, we show how this analysis can be made compatible with a Kaplanian account of first-person indexicals, by identifying the speaker in the context of utterance with the person who has access to the reported private experience
Seasonal variation of the HDO/H2O ratio in the atmosphere of Mars at the middle of northern spring and beginning of northern summer
We present the seasonal variation of the HDO/H2O ratio caused by sublimation-condensation processes in a global view of the martian water cycle. The HDO/H2O ratio was retrieved from ground-based observations using high-dispersion echelle spectroscopy of the Infrared Camera and Spectrograph (IRCS) of the Subaru telescope. Coordinated joint observations were made by the Planetary Fourier Spectrometer (PFS) onboard Mars Express (MEX). The observations were performed during the middle of northern spring (Ls = 52°) and at the beginning of summer (Ls = 96°) in Mars Year 31. The retrieved latitudinal mean HDO/H2O ratios are 4.1 ± 1.4 (Ls = 52°) and 4.4 ± 1.0 (Ls = 96°) times larger than the terrestrial Vienna Standard Mean Ocean Water (VSMOW). The HDO/H2O ratio shows a large seasonal variation at high latitudes. The HDO/H2O ratio significantly increases from 2.4 ± 0.6 wrt VSMOW at Ls = 52° to 5.5 ± 1.1 wrt VSMOW at Ls = 96° over the latitude range between 70°N and 80°N. This can be explained by preferential condensation of HDO vapor during the northern fall, winter, and spring and sublimation of the seasonal polar cap in the northern summer. In addition, we investigated the geographical distribution of the HDO/H2O ratio over low latitudes at the northern spring in the longitudinal range between 220°W and 360°W, including different local times from 10 h to 17 h. We found the HDO/H2O ratio has no significant variation (5.1 ± 1.2 wrt VSMOW) over the entire range. Our observations suggest that the HDO/H2O distribution in the northern spring and summer seasons is mainly controlled by condensation-induced fractionation between the seasonal northern polar cap and the atmosphere
Preliminary analysis of PFS/MEx observations of Comet Siding Spring
On October 19th 2014, Mars experienced a close encounter with Comet C/2013 A1 (Siding Spring), at a distance of 138,000 km. We analyze observations by the Planetary Fourier Spectrometer (PFS) onboard Mars Express performed between October 13th and October 21st 2014 to search for spectral signatures of the comet and to investigate possible effects of its passage on the suspended dust and ice content in the Martian atmosphere
12 years of atmospheric monitoring by the Planetary Fourier Spectrometer onboard Mars Express
We use thermal-infrared spectra returned by the Mars Express Planetary Fourier Spectrometer (PFS-MEx) to retrieve atmospheric and surface temperature, and dust and water ice aerosol optical depth. More than 2,500,000 spectra have been used to build this new dataset, covering the full range of season, latitude, longitude, and local time. The data presented here span more than six Martian years (from MY26, Ls = 331°, 10 January 2004 to MY 33, Ls = 78°, 6 December 2015). We successfully retrieved atmospheric temperatures and aerosols opacity in the polar regions, including the polar nights. By exploiting PFS/MEx capability to perform observations at different local times (LT), this dataset allows investigation of the daily cycles of suspended dust and ice. We present an overview of the seasonal and latitudinal dependence of atmospheric quantities during the relevant period, as well as an assessment of the interannual variability in the current Martian climate, including spatial, daily (LT), seasonal, and interannual variations of the aphelion equatorial cloud belt. With unprecedented spatial and temporal coverage and details revealed, this dataset offers new challenges to the GCMs and, at the same time, a new reference for the MYs complementary to those observed by MGS-TES
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