3,533 research outputs found
NGC 839: Shocks in an M82-like Superwind
We present observations of NGC 839 made with the Wide Field Spectrograph
(WiFeS) on the ANU 2.3m telescope. Our data cover a region 25" x 60" at a
spatial resolution of ~1.5". The long axis of the field is aligned with the
superwind we have discovered in this starburst galaxy. The data cover the range
of 3700-7000 {\AA}, with a spectral resolution R~7000 in the red, and R~3000 in
the blue. We find that the stellar component of the galaxy is strongly
dominated by a fast rotating intermediate-age (~400 Myr) A-Type stellar
population, while the gas is concentrated in a bi-conical polar funnel. We have
generated flux distributions, emission line ratio diagnostics and velocity maps
in both emission and absorption components. We interpret these in the context
of a new grid of low-velocity shock models appropriate for galactic-scale
outflows. These models are remarkably well fit to the data, providing for the
first time model diagnostics for shocks in superwinds and strongly suggesting
that shock excitation is largely responsible for the extended LINER emission in
the outflowing gas in NGC 839. Our work may have important implications both
for extended LINER emission seen in other galaxies, as well as in the
interpretation of objects with "composite" spectra. Finally, we present a
scenario for the formation of E+A galaxies based upon our observations of NGC
839, and its relation to M82.Comment: 12 pages and 13 figures. Accepted for publication in Ap
Follow-up after acute respiratory distress syndrome caused by influenza a (H1N1) virus infection
BACKGROUND: There are no reports on the long-term follow-up of patients with swine-origin influenza A virus infection that progressed to acute respiratory distress syndrome. METHODS: Four patients were prospectively followed up with pulmonary function tests and high-resolution computed tomography for six months after admission to an intensive care unit. RESULTS: Pulmonary function test results assessed two months after admission to the intensive care unit showed reduced forced vital capacity in all patients and low diffusion capacity for carbon monoxide in two patients. At six months, pulmonary function test results were available for three patients. Two patients continued to have a restrictive pattern, and none of the patients presented with abnormal diffusion capacity for carbon monoxide. All of them had a diffuse ground-glass pattern on high-resolution computed tomography that improved after six months. CONCLUSIONS: Despite the marked severity of lung disease at admission, patients with acute respiratory distress syndrome caused by swine-origin influenza A virus infection presented a late but substantial recovery over six months of follow-up
Pressure-induced multiple phase transformations of the BaBi3 superconductor
Measurements of temperature-dependent resistance and magnetization under hydrostatic pressures up to 2.13 GPa are reported for single-crystalline, superconducting BaBi3. A temperature-pressure phase diagram is determined and the results suggest three different superconducting phases α, β, and γ in the studied pressure range. We further show that the occurrence of the three superconducting phases is intuitively linked to phase transitions at higher temperature, which are likely first order and structural in nature. With the α phase being the ambient-pressure tetragonal structure (P4/mmm), our first-principles calculations suggest the β phase has a cubic structure (Pm−3m) and the γ phase has a distorted tetragonal structure where the Bi atoms are moved out of the face-centered position. Finally, an analysis of the evolution of the superconducting upper critical field with pressure further confirms these transitions in the superconducting state and suggests a possible change of band structure or a Lifshitz transition near 1.54 GPa in γ phase. Given the large atomic numbers of both Ba and Bi, our results establish BaBi3 as a good candidate for the study of the interplay of structure with superconductivity in the presence of strong spin-orbit coupling
Eccrine Spiradenoma Arising in the Breast Misdiagnosed as an Epidermal Inclusion Cyst
Eccrine spiradenomas are rare, benign, cutaneous tumors that originate in the sweat glands. Eccrine spiradenomas in the breast are very rare and only a few cases have been reported. We report here on the case of a 47-year-old woman with superficial masses in the breast and these masses had gradually increased in size during follow-up. They were confirmed to be an eccrine spiradenoma on pathologic examination. There have been a few reports about the radiologic findings of eccrine spiradenomas of the breast. This is the first case of an eccrine spiradenoma in the breast that was characterized by multiple imaging modalities, including mammography, ultrasonography and MRI. The lesion in our patient was first diagnosed as an epidermal inclusion cyst based on the imaging findings and the mass's superficial location. Although the mammographic and ultrasonographic imaging findings of eccrine spiradenomas and epidermal inclusion cysts are similar, the MRI findings are different between epidermal inclusion cysts and eccrine spiradenomas. Eccrine spiradenomas should be considered in the differential diagnosis of cutaneous and subcutaneous lesions of the breast
Three-parameter Lorentz-violating texture for neutrino mixing
A three-parameter model of neutrino oscillations based on a simple Lorentz-
and CPT-violating texture is presented. The model is consistent with
established data and naturally generates low-energy and neutrino-antineutrino
anomalies of the MiniBooNE type. A one-parameter extension incorporates the
MINOS anomaly, while a simple texture enhancement accommodates the LSND signal.Comment: 5 pages, accepted for publication in Physics Letters
Collaborative dynamic decision making: a case study from B2B supplier selection
The problem of supplier selection can be easily modeled as a multiple-criteria decision making (MCDM) problem: businesses express their preferences with respect to suppliers, which can then be ranked and selected. This approach has two major pitfalls: first, it does not consider a dynamic scenario, in which suppliers and their ratings are constantly changing; second, it only addressed the problem from the point of view of a single business, and cannot be easily applied when considering more than one business. To overcome these problems, we introduce a method for supplier selection that builds upon the dynamic MCDM framework of Campanella and Ribeiro [1] and, by means of a linear programming model, can be used in the case of multiple collaborating businesses plan- ning their next batch of orders together.Fundação para a Ciência e a Tecnologia, Portugal, under contract CONT DOUT/49/UNINOVA/0/5902/1/200
Accelerated in vivo proliferation of memory phenotype CD4+ T-cells in human HIV-1 infection irrespective of viral chemokine co-receptor tropism.
CD4(+) T-cell loss is the hallmark of HIV-1 infection. CD4 counts fall more rapidly in advanced disease when CCR5-tropic viral strains tend to be replaced by X4-tropic viruses. We hypothesized: (i) that the early dominance of CCR5-tropic viruses results from faster turnover rates of CCR5(+) cells, and (ii) that X4-tropic strains exert greater pathogenicity by preferentially increasing turnover rates within the CXCR4(+) compartment. To test these hypotheses we measured in vivo turnover rates of CD4(+) T-cell subpopulations sorted by chemokine receptor expression, using in vivo deuterium-glucose labeling. Deuterium enrichment was modeled to derive in vivo proliferation (p) and disappearance (d*) rates which were related to viral tropism data. 13 healthy controls and 13 treatment-naive HIV-1-infected subjects (CD4 143-569 cells/ul) participated. CCR5-expression defined a CD4(+) subpopulation of predominantly CD45R0(+) memory cells with accelerated in vivo proliferation (p = 2.50 vs 1.60%/d, CCR5(+) vs CCR5(-); healthy controls; P<0.01). Conversely, CXCR4 expression defined CD4(+) T-cells (predominantly CD45RA(+) naive cells) with low turnover rates. The dominant effect of HIV infection was accelerated turnover of CCR5(+)CD45R0(+)CD4(+) memory T-cells (p = 5.16 vs 2.50%/d, HIV vs controls; P<0.05), naïve cells being relatively unaffected. Similar patterns were observed whether the dominant circulating HIV-1 strain was R5-tropic (n = 9) or X4-tropic (n = 4). Although numbers were small, X4-tropic viruses did not appear to specifically drive turnover of CXCR4-expressing cells (p = 0.54 vs 0.72 vs 0.44%/d in control, R5-tropic, and X4-tropic groups respectively). Our data are most consistent with models in which CD4(+) T-cell loss is primarily driven by non-specific immune activation
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