4,552 research outputs found
Star Formation Rate Indicators in Wide-Field Infrared Survey Preliminary Release
With the goal of investigating the degree to which theMIR luminosity in
theWidefield Infrared Survey Explorer (WISE) traces the SFR, we analyze 3.4,
4.6, 12 and 22 {\mu}m data in a sample of {\guillemotright} 140,000
star-forming galaxies or star-forming regions covering a wide range in
metallicity 7.66 < 12 + log(O/H) < 9.46, with redshift z < 0.4. These
star-forming galaxies or star-forming regions are selected by matching the WISE
Preliminary Release Catalog with the star-forming galaxy Catalog in SDSS DR8
provided by JHU/MPA 1.We study the relationship between the luminosity at 3.4,
4.6, 12 and 22 {\mu}m from WISE and H\alpha luminosity in SDSS DR8. From these
comparisons, we derive reference SFR indicators for use in our analysis. Linear
correlations between SFR and the 3.4, 4.6, 12 and 22 {\mu}m luminosity are
found, and calibrations of SFRs based on L(3.4), L(4.6), L(12) and L(22) are
proposed. The calibrations hold for galaxies with verified spectral
observations. The dispersion in the relation between 3.4, 4.6, 12 and 22 {\mu}m
luminosity and SFR relates to the galaxy's properties, such as 4000 {\deg}A
break and galaxy color.Comment: 10 pages, 3 figure
Scanning-probe spectroscopy of semiconductor donor molecules
Semiconductor devices continue to press into the nanoscale regime, and new
applications have emerged for which the quantum properties of dopant atoms act
as the functional part of the device, underscoring the necessity to probe the
quantum structure of small numbers of dopant atoms in semiconductors[1-3].
Although dopant properties are well-understood with respect to bulk
semiconductors, new questions arise in nanosystems. For example, the quantum
energy levels of dopants will be affected by the proximity of nanometer-scale
electrodes. Moreover, because shallow donors and acceptors are analogous to
hydrogen atoms, experiments on small numbers of dopants have the potential to
be a testing ground for fundamental questions of atomic and molecular physics,
such as the maximum negative ionization of a molecule with a given number of
positive ions[4,5]. Electron tunneling spectroscopy through isolated dopants
has been observed in transport studies[6,7]. In addition, Geim and coworkers
identified resonances due to two closely spaced donors, effectively forming
donor molecules[8]. Here we present capacitance spectroscopy measurements of
silicon donors in a gallium-arsenide heterostructure using a scanning probe
technique[9,10]. In contrast to the work of Geim et al., our data show
discernible peaks attributed to successive electrons entering the molecules.
Hence this work represents the first addition spectrum measurement of dopant
molecules. More generally, to the best of our knowledge, this study is the
first example of single-electron capacitance spectroscopy performed directly
with a scanning probe tip[9].Comment: In press, Nature Physics. Original manuscript posted here; 16 pages,
3 figures, 5 supplementary figure
The diagnosis of mental disorders: the problem of reification
A pressing need for interrater reliability in the diagnosis of mental disorders
emerged during the mid-twentieth century, prompted in part by
the development of diverse new treatments. The Diagnostic and Statistical
Manual of Mental Disorders (DSM), third edition answered this need
by introducing operationalized diagnostic criteria that were field-tested
for interrater reliability. Unfortunately, the focus on reliability came at a
time when the scientific understanding of mental disorders was embryonic
and could not yield valid disease definitions. Based on accreting
problems with the current DSM-fourth edition (DSM-IV) classification,
it is apparent that validity will not be achieved simply by refining
criteria for existing disorders or by the addition of new disorders. Yet
DSM-IV diagnostic criteria dominate thinking about mental disorders
in clinical practice, research, treatment development, and law. As a result,
the modernDSMsystem, intended to create a shared language, also
creates epistemic blinders that impede progress toward valid diagnoses.
Insights that are beginning to emerge from psychology, neuroscience,
and genetics suggest possible strategies for moving forward
H_2 emission arises outside photodissociation regions in ultra-luminous infrared galaxies
Ultra-luminous infrared galaxies are among the most luminous objects in the
local universe and are thought to be powered by intense star formation. It has
been shown that in these objects the rotational spectral lines of molecular
hydrogen observed at mid-infrared wavelengths are not affected by dust
obscuration, leaving unresolved the source of excitation of this emission. Here
I report an analysis of archival Spitzer Space Telescope data on ultra-luminous
infrared galaxies and demonstrate that star formation regions are buried inside
optically thick clouds of gas and dust, so that dust obscuration affects
star-formation indicators but not molecular hydrogen. I thereby establish that
the emission of H_2 is not co-spatial with the buried starburst activity and
originates outside the obscured regions. This is rather surprising in light of
the standard view that H_2 emission is directly associated with star-formation
activity. Instead, I propose that H_2 emission in these objects traces shocks
in the surrounding material, which are in turn excited by interactions with
nearby galaxies, and that powerful large-scale shocks cooling by means of H_2
emission may be much more common than previously thought. In the early
universe, a boost in H_2 emission by this process may speed up the cooling of
matter as it collapsed to form the first stars and galaxies and would make
these first structures more readily observable.Comment: Main text and supplemental information, 21 pages including 6 figures,
2 table
Clinical implications of increased lymph vessel density in the lymphatic metastasis of early-stage invasive cervical carcinoma: a clinical immunohistochemical method study
<p>Abstract</p> <p>Background</p> <p>Cervical cancer is the most common malignant gynecological cancer, and lymphatic metastasis can occur in the early stage of tumor growth. Lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), a marker for lymphatic endothelium, provides powerful tools for studying tumor lymphangiogenesis. The purpose of this study is to investigate the clinical implications of lymphangiogenesis in the metastasis of early-stage invasive cervical carcinoma.</p> <p>Methods</p> <p>We used immunohistochemical (IHC) staining with the antibody against LYVE-1 to measure lymph vessel density in 41 cases of early-stage invasive cervical carcinoma and 12 cases of normal cervical samples. We then analyzed the correlation between lymph vessel density and clinicopathological features of the tumors.</p> <p>Results</p> <p>(1) The majority of peritumoral lymphatics were enlarged, dilated, and irregular. In contrast, intratumoral lymph vessels were small and collapsed. The peritumoral lymphatic vessel density (PLVD) was significantly higher than the intratumoral lymphatic vessel density (ILVD) (<it>P </it>< 0.01). (2) Both ILVD and PLVD were significantly higher than the LVD of the control cervixes (<it>P </it>< 0.01). (3) Both ILVD and PLVD were significantly associated with lymph node metastasis (ILVD, <it>P </it>< 0.05; PLVD, <it>P </it>< 0.01) and lymphatic vessel invasion (ILVD, <it>P </it>< 0.05; PLVD, <it>P </it>< 0.01). Both the ILVD and PLVD in patients with histological grade HG2 and HG3 were significantly higher than those with HG1 (<it>P </it>< 0.05).</p> <p>Conclusion</p> <p>Tumor lymphangiogenesis in early-stage invasive cervical carcinoma may play an important role in the process of lymphatic metastasis.</p
The Human Fungal Pathogen Cryptococcus neoformans Escapes Macrophages by a Phagosome Emptying Mechanism That Is Inhibited by Arp2/3 Complex-Mediated Actin Polymerisation
The lysis of infected cells by disease-causing microorganisms is an efficient but risky strategy for disseminated infection, as it exposes the pathogen to the full repertoire of the host's immune system. Cryptococcus neoformans is a widespread fungal pathogen that causes a fatal meningitis in HIV and other immunocompromised patients. Following intracellular growth, cryptococci are able to escape their host cells by a non-lytic expulsive mechanism that may contribute to the invasion of the central nervous system. Non-lytic escape is also exhibited by some bacterial pathogens and is likely to facilitate long-term avoidance of the host immune system during latency. Here we show that phagosomes containing intracellular cryptococci undergo repeated cycles of actin polymerisation. These actin ‘flashes’ occur in both murine and human macrophages and are dependent on classical WASP-Arp2/3 complex mediated actin filament nucleation. Three dimensional confocal imaging time lapse revealed that such flashes are highly dynamic actin cages that form around the phagosome. Using fluorescent dextran as a phagosome membrane integrity probe, we find that the non-lytic expulsion of Cryptococcus occurs through fusion of the phagosome and plasma membranes and that, prior to expulsion, 95% of phagosomes become permeabilised, an event that is immediately followed by an actin flash. By using pharmacological agents to modulate both actin dynamics and upstream signalling events, we show that flash occurrence is inversely related to cryptococcal expulsion, suggesting that flashes may act to temporarily inhibit expulsion from infected phagocytes. In conclusion, our data reveal the existence of a novel actin-dependent process on phagosomes containing cryptococci that acts as a potential block to expulsion of Cryptococcus and may have significant implications for the dissemination of, and CNS invasion by, this organism.\ud
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Modulated Instability in Five-Dimensional U(1) Charged AdS Black Hole with R**2-term
We study the effect of R**2 term to the modulated instability in the U(1)
charged black hole in five-dimensional Anti-de Sitter space-time. We consider
the first-order corrections of R**2 term to the background and the linear order
perturbations in the equations of motion. From the analysis, we clarify the
effect of R**2 term in the modulated instability, and conclude that
fluctuations are stable in the whole bulk in the range of values the
coefficient of R**2 term can take.Comment: 19 pages, 1 figures; (v4) Published version in JHE
Rapid EST isolation from chromosome 1R of rye
<p>Abstract</p> <p>Background</p> <p>To obtain important expressed sequence tags (ESTs) located on specific chromosomes is currently difficult. Construction of single-chromosome EST library could be an efficient strategy to isolate important ESTs located on specific chromosomes. In this research we developed a method to rapidly isolate ESTs from chromosome 1R of rye by combining the techniques of chromosome microdissection with hybrid specific amplification (HSA).</p> <p>Results</p> <p>Chromosome 1R was isolated by a glass needle and digested with proteinase K (PK). The DNA of chromosome 1R was amplified by two rounds of PCR using a degenerated oligonucleotide 6-MW sequence with a <it>Sau</it>3AI digestion site as the primer. The PCR product was digested with <it>Sau</it>3AI and linked with adaptor HSA1, then hybridized with the <it>Sau</it>3AI digested cDNA with adaptor HSA2 of rye leaves with and without salicylic acid (SA) treatment, respectively. The hybridized DNA fragments were recovered by the HSA method and cloned into pMD18-T vector. The cloned inserts were released by PCR using the partial sequences in HSA1 and HSA2 as the primers and then sequenced. Of the 94 ESTs obtained and analyzed, 6 were known sequences located on rye chromosome 1R or on homologous group 1 chromosomes of wheat; all of them were highly homologous with ESTs of wheat, barley and/or other plants in <it>Gramineae</it>, some of which were induced by abiotic or biotic stresses. Isolated in this research were 22 ESTs with unknown functions, probably representing some new genes on rye chromosome 1R.</p> <p>Conclusion</p> <p>We developed a new method to rapidly clone chromosome-specific ESTs from chromosome 1R of rye. The information reported here should be useful for cloning and investigating the new genes found on chromosome 1R.</p
Responsiveness differences in outcome instruments after revision hip arthroplasty: What are the implications?
Responsiveness to change is an important psychometric property of an outcome instrument. Assessment of health-related quality of life (HRQoL) is critical to outcome assessment after total joint replacement, a surgery aimed at improving pain, function and HRQoL of the patients undergoing these procedures. In a recent study, Shi et al. examined the responsiveness to change of various subscales of two instruments, physician-administered Harris Hip Score and patient self-administered Short Form-36 (SF-36), 6 months after revision total hip arthroplasty. The responsiveness statistics for both scales were reasonable, higher for Harris Hip Score than SF-36. This is the first study to examine responsiveness of these instruments in revision THA patients in a systematic fashion
Fast synthesis of platinum nanopetals and nanospheres for highly-sensitive non-enzymatic detection of glucose and selective sensing of ions
Novel methods to obtain Pt nanostructured electrodes have raised particular interest due to their high performance in electrochemistry. Several nanostructuration methods proposed in the literature use costly and bulky equipment or are time-consuming due to the numerous steps they involve. Here, Pt nanostructures were produced for the first time by one-step template-free electrodeposition on Pt bare electrodes. The change in size and shape of the nanostructures is proven to be dependent on the deposition parameters and on the ratio between sulphuric acid and chloride-complexes (i.e., hexachloroplatinate or tetrachloroplatinate). To further improve the electrochemical properties of electrodes, depositions of Pt nanostructures on previously synthesised Pt nanostructures are also performed. The electroactive surface areas exhibit a two order of magnitude improvement when Pt nanostructures with the smallest size are used. All the biosensors based on Pt nanostructures and immobilised glucose oxidase display higher sensitivity as compared to bare Pt electrodes. Pt nanostructures retained an excellent electrocatalytic activity towards the direct oxidation of glucose. Finally, the nanodeposits were proven to be an excellent solid contact for ion measurements, significantly improving the time-stability of the potential. The use of these new nanostructured coatings in electrochemical sensors opens new perspectives for multipanel monitoring of human metabolism
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