143 research outputs found
New radio observations of anomalous microwave emission in the HII region RCW175
We have observed the HII region RCW175 with the 64m Parkes telescope at
8.4GHz and 13.5GHz in total intensity, and at 21.5GHz in both total intensity
and polarization. High angular resolution, high sensitivity, and polarization
capability enable us to perform a detailed study of the different constituents
of the HII region. For the first time, we resolve three distinct regions at
microwave frequencies, two of which are part of the same annular diffuse
structure. Our observations enable us to confirm the presence of anomalous
microwave emission (AME) from RCW175. Fitting the integrated flux density
across the entire region with the currently available spinning dust models,
using physically motivated assumptions, indicates the presence of at least two
spinning dust components: a warm component with a relatively large hydrogen
number density n_H=26.3/cm^3 and a cold component with a hydrogen number
density of n_H=150/cm^3. The present study is an example highlighting the
potential of using high angular-resolution microwave data to break model
parameter degeneracies. Thanks to our spectral coverage and angular resolution,
we have been able to derive one of the first AME maps, at 13.5GHz, showing
clear evidence that the bulk of the AME arises in particular from one of the
source components, with some additional contribution from the diffuse
structure. A cross-correlation analysis with thermal dust emission has shown a
high degree of correlation with one of the regions within RCW175. In the center
of RCW175, we find an average polarized emission at 21.5GHz of
2.2\pm0.2(rand.)\pm0.3(sys.)% of the total emission, where we have included
both systematic and statistical uncertainties at 68% CL. This polarized
emission could be due to sub-dominant synchrotron emission from the region and
is thus consistent with very faint or non-polarized emission associated with
AME.Comment: Accepted for publication in the Astrophysical Journa
The pros and cons of the inversion method approach to derive 3D dust emission properties in the ISM: the Hi-GAL field centred on (l, b) = (30°, 0°)
Herschel far-infrared continuum data obtained as part of the Hi-GAL survey have been used, together with the GLIMPSE 8 μm and MIPSGAL 24 μm data, to attempt the first 3D-decomposition of dust emission associated with atomic, molecular and ionized gas at 15 arcmin angular resolution. Our initial test case is a 2 × 2 square degrees region centred on (l, b) = (30°, 0°), a direction that encompasses the origin point of the Scutum–Crux Arm at the tip of the Galactic Bar. Coupling the IR maps with velocity maps specific for different gas phases (H i 21cm, ^(12)CO and ^(13)CO, and radio recombination lines), we estimate the properties of dust blended with each of the gas components and at different Galactocentric distances along the line of sight (LOS). A statistical Pearson's coefficients analysis is used to study the correlation between the column densities estimated for each gas component and the intensity of the IR emission. This analysis provides evidence that the 2 × 2 square degree field under consideration is characterized by the presence of a gas component not accounted for by the standard tracers, possibly associated with warm H_2 and cold H I. We demonstrate that the IR radiation in the range 8 < λ < 500 μm is systematically dominated by emission originating within the Scutum–Crux Arm. By applying an inversion method, we recover the dust emissivities associated with atomic, molecular and ionized gas. Using the DustEM model, we fit the spectral energy distributions for each gas phase, and find average dust temperatures of T_(d,H I) = 18.82 ± 0.47 K, T_(d,H_2) = 18.84 ± 1.06 K and T_(d,H II) = 22.56 ± 0.64 K, respectively. We also obtain an indication for polycyclic aromatic hydrocarbons depletion in the diffuse ionized gas. We demonstrate the importance of including the ionized component in 3D-decompositions of the total IR emission. However, the main goal of this work is to discuss the impact of the missing column density associated with the dark gas component on the accurate evaluation of the dust properties, and to shed light on the limitations of the inversion method approach when this is applied to a small section of the Galactic plane and when the working resolution allows sufficient de-blending of the gas components along the LOS
A search for interstellar anthracene toward the Perseus anomalous microwave emission region
We report the discovery of a new broad interstellar (or circumstellar) band
at 7088.8 +- 2.0 \AA coincident to within the measurement uncertainties with
the strongest band of the anthracene cation (CH) as measured
in gas-phase laboratory spectroscopy at low temperatures (Sukhorukov et
al.2004). The band is detected in the line of sight of star Cernis 52, a likely
member of the very young star cluster IC 348, and is probably associated with
cold absorbing material in a intervening molecular cloud of the Perseus star
forming region where various experiments have recently detected anomalous
microwave emission. From the measured intensity and available oscillator
strength we find a column density of N= 1.1(+-0.4) x 10
cm implying that ~0.008% of the carbon in the cloud could be in the form
of CH. A similar abundance has been recently claimed for the
naphthalene cation (Iglesias-Groth et al. 2008) in this cloud. This is the
first location outside the Solar System where specific PAHs are identified. We
report observations of interstellar lines of CH and CH that support a
rather high column density for these species and for molecular hydrogen. The
strength ratio of the two prominent diffuse interstellar bands at 5780 and 5797
\AA suggests the presence of a ``zeta'' type cloud in the line of sight
(consistent with steep far-UV extinction and high molecular content). The
presence of PAH cations and other related hydrogenated carbon molecules which
are likely to occur in this type of clouds reinforce the suggestion that
electric dipole radiation from fast spinning PAHs is responsible of the
anomalous microwave emission detected toward Perseus.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical
Societ
Closing in on a new treatment for sleeping sickness
A chemoproteomics approach has been employed to identify a kinase that could be used as a druggable target in efforts to develop new treatments for African sleeping sickness
The State-of-Play of Anomalous Microwave Emission (AME) Research
Anomalous Microwave Emission (AME) is a component of diffuse Galactic
radiation observed at frequencies in the range -60 GHz. AME was
first detected in 1996 and recognised as an additional component of emission in
1997. Since then, AME has been observed by a range of experiments and in a
variety of environments. AME is spatially correlated with far-IR thermal dust
emission but cannot be explained by synchrotron or free-free emission
mechanisms, and is far in excess of the emission contributed by thermal dust
emission with the power-law opacity consistent with the observed emission at
sub-mm wavelengths. Polarization observations have shown that AME is very
weakly polarized (%). The most natural explanation for AME is
rotational emission from ultra-small dust grains ("spinning dust"), first
postulated in 1957. Magnetic dipole radiation from thermal fluctuations in the
magnetization of magnetic grain materials may also be contributing to the AME,
particularly at higher frequencies ( GHz). AME is also an important
foreground for Cosmic Microwave Background analyses. This paper presents a
review and the current state-of-play in AME research, which was discussed in an
AME workshop held at ESTEC, The Netherlands, June 2016.Comment: Accepted for publication in New Astronomy Reviews. Summary of AME
workshop held at ESTEC, The Netherlands, June 2016, 40 pages, 18 figures.
Updated to approximately match published versio
The geometry of the magnetic field in the central molecular zone measured by PILOT
We present the first far infrared (FIR) dust emission polarization map covering the full extent of Milky Way’s central molecular zone (CMZ). The data, obtained with the PILOT balloon-borne experiment, covers the Galactic center region − 2° < ℓ < 2°, − 4° < b < 3° at a wavelength of 240 μm and an angular resolution of 2.2′. From our measured dust polarization angles, we infer a magnetic field orientation projected onto the plane of the sky (POS) that is remarkably ordered over the full extent of the CMZ, with an average tilt angle of ≃22° clockwise with respect to the Galactic plane. Our results confirm previous claims that the field traced by dust polarized emission is oriented nearly orthogonally to the field traced by GHz radio synchrotron emission in the Galactic center region. The observed field structure is globally compatible with the latest Planck polarization data at 353 and 217 GHz. Upon subtraction of the extended emission in our data, the mean field orientation that we obtain shows good agreement with the mean field orientation measured at higher angular resolution by the JCMT within the 20 and 50 km s−1 molecular clouds. We find no evidence that the magnetic field orientation is related to the 100 pc twisted ring structure within the CMZ. The low polarization fraction in the Galactic center region measured with Planck at 353 GHz combined with a highly ordered projected field orientation is unusual. This feature actually extends to the whole inner Galactic plane. We propose that it could be caused by the increased number of turbulent cells for the long lines of sight towards the inner Galactic plane or to dust properties specific to the inner regions of the Galaxy. Assuming equipartition between magnetic pressure and ram pressure, we obtain magnetic field strength estimates of the order of 1 mG for several CMZ molecular clouds
Correlates of HCV seropositivity among familial contacts of HCV positive patients
BACKGROUND: Determinants of intrafamilial HCV transmission are still being debated. The aim of this study is to investigate the correlates of HCV seropositivity among familial contacts of HCV positive patients in Italy. METHODS: A cross-sectional study was conducted with 175 HCV positive patients (index cases), recruited from Policlinico Gemelli in Rome as well as other hospitals in Central Italy between 1995 and 2000 (40% female, mean age 57 ± 15.2 years), and 259 familial contacts. Differences in proportions of qualitative variables were tested with non-parametric tests (χ(2), Yates correction, Fisher exact test), and a p value < 0.05 was considered significant. A multivariate analysis was conducted using logistic regression in order to verify which variables statistically have an influence on HCV positivity in contact individuals. RESULTS: Seropositivity for HCV was found in 8.9% of the contacts. From the univariate analysis, risk factors significantly associated to HCV positivity in the contacts were: intravenous drug addiction (p = 0.004) and intercourse with drug addicts (p = 0.005). The only variables associated significantly and independently to HCV seropositivity in patients' contacts were intercourse with drug addicts (OR = 19.28; 95% CI: 2.01 – 184.94), the retirement status from work (OR = 3.76; 95% CI: 1.17 – 11.98), the time of the relationship (OR = 1.06; 95% CI: 1.00 – 1.11) and tattoos (OR = 7.68; 95% CI: 1.00 – 60.20). CONCLUSION: The present study confirms that having intercourse with a drug addict is the most significant risk factor for intrafamilial HCV transmission. The association with retirement status from work could be related to both a long-term relationship with an index case and past exposure to common risk factors
Inhibition of cerebrovascular raf activation attenuates cerebral blood flow and prevents upregulation of contractile receptors after subarachnoid hemorrhage
<p>Abstract</p> <p>Background</p> <p>Late cerebral ischemia carries high morbidity and mortality after subarachnoid hemorrhage (SAH) due to reduced cerebral blood flow (CBF) and the subsequent cerebral ischemia which is associated with upregulation of contractile receptors in the vascular smooth muscle cells (SMC) via activation of mitogen-activated protein kinase (MAPK) of the extracellular signal-regulated kinase (ERK)1/2 signal pathway. We hypothesize that SAH initiates cerebrovascular ERK1/2 activation, resulting in receptor upregulation. The raf inhibitor will inhibit the molecular events upstream ERK1/2 and may provide a therapeutic window for treatment of cerebral ischemia after SAH.</p> <p>Results</p> <p>Here we demonstrate that SAH increases the phosphorylation level of ERK1/2 in cerebral vessels and reduces the neurology score in rats in additional with the CBF measured by an autoradiographic method. The intracisternal administration of SB-386023-b, a specific inhibitor of raf, given 6 h after SAH, aborts the receptor changes and protects the brain from the development of late cerebral ischemia at 48 h. This is accompanied by reduced phosphorylation of ERK1/2 in cerebrovascular SMC. SAH per se enhances contractile responses to endothelin-1 (ET-1), 5-carboxamidotryptamine (5-CT) and angiotensin II (Ang II), upregulates ET<sub>B</sub>, 5-HT<sub>1B </sub>and AT<sub>1 </sub>receptor mRNA and protein levels. Treatment with SB-386023-b given as late as at 6 h but not at 12 h after the SAH significantly decreased the receptor upregulation, the reduction in CBF and the neurology score.</p> <p>Conclusion</p> <p>These results provide evidence for a role of the ERK1/2 pathway in regulation of expression of cerebrovascular SMC receptors. It is suggested that raf inhibition may reduce late cerebral ischemia after SAH and provides a realistic time window for therapy.</p
Hi-GAL, theHerschelinfrared Galactic Plane Survey: photometric maps and compact source catalogues
Aims. We present the first public release of high-quality data products (DR1) from Hi-GAL, the Herschel infrared Galactic Plane Survey. Hi-GAL is the keystone of a suite of continuum Galactic plane surveys from the near-IR to the radio and covers five wavebands at 70, 160, 250, 350 and 500 µm, encompassing the peak of the spectral energy distribution of cold dust for 8 < T < 50 K. This first Hi-GAL data release covers the inner
Milky Way in the longitude range 68◦ > t > −70◦ in a |b| ≤ 1◦ latitude strip. ∼ ∼
∼ ∼
Methods. Photometric maps have been produced with the ROMAGAL pipeline, which optimally capitalizes on the excellent sensitivity and
stability of the bolometer arrays of the Herschel PACS and SPIRE photometric cameras. It delivers images of exquisite quality and dynamical range, absolutely calibrated with Planck and IRAS, and recovers extended emission at all wavelengths and all spatial scales, from the point-spread function to the size of an entire 2◦ × 2◦ “tile” that is the unit observing block of the survey. The compact source catalogues were generated with the CuTEx algorithm, which was specifically developed to optimise source detection and extraction in the extreme conditions of intense and spatially varying background that are found in the Galactic plane in the thermal infrared.
Results. Hi-GAL DR1 images are cirrus noise limited and reach the 1σ-rms predicted by the Herschel Time Estimators for parallel-mode obser- vations at 6011 s−1 scanning speed in relatively low cirrus emission regions. Hi-GAL DR1 images will be accessible through a dedicated web-based image cutout service. The DR1 Compact Source Catalogues are delivered as single-band photometric lists containing, in addition to source posi- tion, peak, and integrated flux and source sizes, a variety of parameters useful to assess the quality and reliability of the extracted sources. Caveats and hints to help in this assessment are provided. Flux completeness limits in all bands are determined from extensive synthetic source experiments and greatly depend on the specific line of sight along the Galactic plane because the background strongly varies as a function of Galactic longitude. Hi-GAL DR1 catalogues contain 123210, 308509, 280685, 160972, and 85460 compact sources in the five bands
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