ABSTRACT We present key results from the Herschel Orion Protostar Survey: spectral energy distributions (SEDs) and model fits of 330 young stellar objects, predominantly protostars, in the Orion ...molecular clouds. This is the largest sample of protostars studied in a single, nearby star formation complex. With near-infrared photometry from 2MASS, mid- and far-infrared data from Spitzer and Herschel, and submillimeter photometry from APEX, our SEDs cover 1.2-870 m and sample the peak of the protostellar envelope emission at ∼100 m. Using mid-IR spectral indices and bolometric temperatures, we classify our sample into 92 Class 0 protostars, 125 Class I protostars, 102 flat-spectrum sources, and 11 Class II pre-main-sequence stars. We implement a simple protostellar model (including a disk in an infalling envelope with outflow cavities) to generate a grid of 30,400 model SEDs and use it to determine the best-fit model parameters for each protostar. We argue that far-IR data are essential for accurate constraints on protostellar envelope properties. We find that most protostars, and in particular the flat-spectrum sources, are well fit. The median envelope density and median inclination angle decrease from Class 0 to Class I to flat-spectrum protostars, despite the broad range in best-fit parameters in each of the three categories. We also discuss degeneracies in our model parameters. Our results confirm that the different protostellar classes generally correspond to an evolutionary sequence with a decreasing envelope infall rate, but the inclination angle also plays a role in the appearance, and thus interpretation, of the SEDs.
ABSTRACT We present a near-infrared survey for the visual multiples in the Orion molecular clouds region at separations between 100 and 1000 au. These data were acquired at 1.6 m with the NICMOS and ...WFC3 cameras on the Hubble Space Telescope. Additional photometry was obtained for some of the sources at 2.05 m with NICMOS and in the L′ band with NSFCAM2 on NASA's InfraRed Telescope Facility. Toward 129 protostars and 197 pre-main-sequence stars with disks observed with WFC3, we detect 21 and 28 candidate companions between the projected separations of 100-1000 au, of which less than 5 and 8, respectively, are chance line-of-sight coincidences. The resulting companion fraction (CF) after the correction for the line-of-sight contamination is 14.4 − 1.3 + 1.1 % for protostars and 12.5 − 0.8 + 1.2 % for the pre-main-sequence stars. These values are similar to those found for main-sequence stars, suggesting that there is little variation in the CF with evolution, although several observational biases may mask a decrease in the CF from protostars to the main-sequence stars. After segregating the sample into two populations based on the surrounding surface density of young stellar objects, we find that the CF in the high stellar density regions ( YSO > 45 pc−2) is approximately 50% higher than that found in the low stellar density regions ( YSO < 45 pc−2). We interpret this as evidence for the elevated formation of companions at 100-1000 au in the denser environments of Orion. We discuss possible reasons for this elevated formation.
Neuroprotective strategies, including free radical scavengers, ion channel modulators, and anti-inflammatory agents, have been extensively explored in the last 2 decades for the treatment of ...neurological diseases. Unfortunately, none of the neuroprotectants has been proved effective in clinical trails. In the current study, we demonstrated that methylene blue (MB) functions as an alternative electron carrier, which accepts electrons from NADH and transfers them to cytochrome c and bypasses complex I/III blockage. A de novo synthesized MB derivative, with the redox center disabled by N-acetylation, had no effect on mitochondrial complex activities. MB increases cellular oxygen consumption rates and reduces anaerobic glycolysis in cultured neuronal cells. MB is protective against various insults in vitro at low nanomolar concentrations. Our data indicate that MB has a unique mechanism and is fundamentally different from traditional antioxidants. We examined the effects of MB in two animal models of neurological diseases. MB dramatically attenuates behavioral, neurochemical, and neuropathological impairment in a Parkinson disease model. Rotenone caused severe dopamine depletion in the striatum, which was almost completely rescued by MB. MB rescued the effects of rotenone on mitochondrial complex I-III inhibition and free radical overproduction. Rotenone induced a severe loss of nigral dopaminergic neurons, which was dramatically attenuated by MB. In addition, MB significantly reduced cerebral ischemia reperfusion damage in a transient focal cerebral ischemia model. The present study indicates that rerouting mitochondrial electron transfer by MB or similar molecules provides a novel strategy for neuroprotection against both chronic and acute neurological diseases involving mitochondrial dysfunction.
Dust grains are nucleation centers and catalysts for the growth of icy mantles in quiescent interstellar clouds, the products of which may accumulate into preplanetary matter when new stars and solar ...systems form within the clouds. In this paper, we present the first spectroscopic detections of silicate dust and the molecular ices H sub(2)O, CO, and CO sub(2) in the vicinity of the prestellar core L183 (L134N). An infrared photometric survey of the cloud was used to identify reddened background stars, and we present spectra covering solid-state absorption features in the wavelength range 2-20 mu m for nine of them. The mean composition of the ices in the best-studied line of sight (toward J15542044-0254073) is H sub(2)O:CO:CO sub(2) approx = 100:40:24. The ices are amorphous in structure, indicating that they have been maintained at low temperature (<, ~ 15 K) since formation. The ice column density N(H sub(2)O) correlates with reddening by dust, exhibiting a threshold effect that corresponds to the transition from unmantled grains in the outer layers of the cloud to ice-mantled grains within, analogous to that observed in other dark clouds. A comparison of results for L183 and the Taurus and IC 5146 dark clouds suggests common behavior, with mantles first appearing in each case at a dust column corresponding to a peak optical depth tau sub(9.7) = 0.15 + or - 0.03 in the silicate feature. Our results support a previous conclusion that the color excess EJ - K does not obey a simple linear correlation with the total dust column in lines of sight that intercept dense clouds. The most likely explanation is a systematic change in the optical properties of the dust as the density increases.
Context. Extinction and emission of dust models need for observational constraints to be validated. The coreshine phenomenon has already shown the importance of scattering in the 3 to 5 μm range and ...its ability to validate dust properties for dense cores. Aims. We want to investigate whether scattering can also play a role at longer wavelengths and to place even tighter constraints on the dust properties. Methods. We analyze the inversion of the Spitzer 8 μm map of the dense molecular cloud L183, to examine the importance of scattering as a potential contributor to the line-of-sight extinction. Results. The column density deduced from the inversion of the 8 μm map, when we neglect scattering, disagrees with all the other column density measurements of the same region. Modeling confirms that scattering at 8 μm is not negligible with an intensity of several hundred kJy sr-1. This demonstrates the need of efficiently scattering dust grains at mid-infrared wavelengths up to 8 μm. Coagulated aggregates are good candidates and might also explain the discrepancy at high extinction between E(J − K) and τ9.7 toward dense molecular clouds. Further investigation requires considering efficiently scattering dust grains including ices as realistic dust models.
Studies have shown that blockade of CTLA-4 promoted the expansion of germinal center B-cells in viral infection or immunization with model antigens. Few studies have evaluated the immunological ...consequences of CTLA-4 blockade during immunization against relevant vaccine candidates. Here, we investigated the effects of CTLA-4 blockade on HIV virus-like particles (VLPs) vaccination in a C57BL/6J mouse model. We found that CTLA-4 blockade during HIV VLP immunization resulted in increased CD4+ T-cell activation, promoted the expansion of HIV envelope (Env)-specific follicular helper T cell (Tfh) cells, and significantly increased HIV Gag- and Env-specific IgG with higher avidity and antibody-dependent cellular cytotoxicity (ADCC) capabilities. Furthermore, after only a single immunization, CTLA-4 blockade accelerated T-cell dependent IgG class switching and the induction of significantly high serum levels of the B-cell survival factor, A proliferation-inducing ligand (APRIL). Although no significant increase in neutralizing antibodies was observed, increased levels of class-switched Env- and Gag-specific IgG are indicative of increased polyclonal B-cell activation, which demonstrated the ability to mediate and enhance ADCC in this study. Altogether, our findings show that CTLA-4 blockade can increase the levels of HIV antigen-specific B-cell and antigen-specific Tfh cell activity and impact humoral immune responses when combined with a clinically relevant HIV VLP-based vaccine.
We present 70 and 160 μm Herschel science demonstration images of a field in the Orion A molecular cloud that contains the prototypical Herbig-Haro objects HH 1 and 2, obtained with the Photodetector ...Array Camera and Spectrometer (PACS). These observations demonstrate Herschel's unprecedented ability to study the rich population of protostars in the Orion molecular clouds at the wavelengths where they emit most of their luminosity. The four protostars previously identified by Spitzer 3.6–40 μm imaging and spectroscopy are detected in the 70 μm band, and three are clearly detected at 160 μm. We measure photometry of the protostars in the PACS bands and assemble their spectral energy distributions (SEDs) from 1 to 870 μm with these data, Spitzer spectra and photometry, 2MASS data, and APEX sub-mm data. The SEDs are fit to models generated with radiative transfer codes. From these fits we can constrain the fundamental properties of the protostars. We find luminosities in the range 12–84 $L_{\odot}$ and envelope densities spanning over two orders of magnitude. This implies that the four protostars have a wide range of envelope infall rates and evolutionary states: two have dense, infalling envelopes, while the other two have only residual envelopes. We also show the highly irregular and filamentary structure of the cold dust and gas surrounding the protostars as traced at 160 μm.
Neuroinflammation is a complex process involving cells from the immune system and the central nerve system (CNS). Polymorphonuclear neutrophils (PMN) are the most abundant class of white blood cells, ...and typically the first type of leukocyte recruited to sites of inflammation. In the CNS, astrocytes are the most abundant glial cell population and participate in the local innate immune response triggered by a variety of insults. In the present study, we investigated the impacts of astrocytes on PMN function.
Primary astrocyte cultures were derived from postnatal C57BL/6 mice and primary neutrophils were isolated from 8 to 12 weeks old C57BL/6 mice. PMNs respiratory burst was analyzed by H2DCFDA assay. For phagocytosis assay, neutrophils were incubated with FITC-labeled E. coli and the phagocytosis of E coli was determined by flow cytometer. PMNs degranulation was determined by myeloperoxidase assay. Cytokine expression was determined by real-time PCR. To determine the involvement of different signaling pathway, protein lysates were prepared and western blots were conducted to assess the activation of Akt, Erk1/2, and p38.
Using ex vivo neutrophils and primary astrocyte cultures, our study demonstrated that astrocytes differentially regulate neutrophil functions, depending upon whether the interactions between the two cell types are direct or indirect. Upon direct cell-cell contact, astrocytes attenuate neutrophil apoptosis, respiratory bust, and degranulation, while enhancing neutrophil phagocytic capability and pro-inflammatory cytokine expression. Through indirect interaction with neutrophils, astrocytes attenuate apoptosis and enhance necrosis in neutrophils, augment neutrophil phagocytosis and respiratory burst, and inhibit neutrophil degranulation. In addition, astrocytes could augment Akt, Erk1/2, and p38 activation in neutrophils.
Astrocytes differentially regulate neutrophil functions through direct or indirect interactions between the two cell types. The diversified actions of astrocytes on neutrophils might provide protection against potential microbial infections given compromised blood-brain barrier integrity under certain neuropathological conditions. The complex actions of astrocytes on neutrophils could provide further insight to harness the inflammatory response to promote CNS repair.
We present the results of intensive visual-broadband photometric monitoring of the highly variable WN8 Wolf-Rayet star WR 123, obtained by the MOST (Microvariability and Oscillations of STars) ...satellite. This first Canadian astronomical space telescope observed WR 123 for 38 days nonstop during 2004 June and July. Fourier analysis shows that no periodic signal is stable for more than several days in the low-frequency domain (f < 1 day super(-1)), where most of the stochastic power is contained. Also, no significant variability is seen in the high-frequency domain (10 day super(-1) < if < 1400 day super(-1)) down to the level of 0.2 mmag, an order of magnitude lower than theoretical predictions for strange-mode pulsations. On the other hand, there seems to be a relatively stable 9.8 hr periodic signal present throughout the whole run. This period is probably too short to represent the axial rotation of the star, unless it is related to multiple substructures equidistantly spread along the stellar equator. It is also too short to be orbital in nature; it is more likely to be related to pulsational instabilities (although with a much longer period than expected), thus finally revealing a possible fundamental driver behind the highly variable wind of this object, and others of similar type.
Context. The ν2 bending mode of pure CO2 ice around 15.2 μm exhibits a fine double-peak structure that offers a sensitive probe to study the physical and chemical properties of solid CO2 in space. ...Current laboratory spectra do not fully resolve the CO2 ice features. Aims. To improve the fitting of the observed CO2 features, high-resolution solid-state infrared spectra of pure CO2 ice are recorded in the laboratory for a series of astronomically relevant temperatures and at an unprecedented level of detail. Methods. The infrared spectra of pure CO2 ice were recorded in the 4000 to 400 cm-1 (2.5–25 μm) region at a resolution of 0.1 cm-1 using Fourier transform infrared spectroscopy. Results. Accurate band positions and band widths (FWHM) of pure CO2 ice are presented for temperatures of 15, 30, 45, 60, and 75 K. The focus of this spectroscopic work is on the CO2 (ν2) bending mode, but more accurate data are also reported for the 12CO2 and 13CO2 (ν3) stretching mode, and CO2 (ν1+ν3) and (2ν2+ν3) combination bands.
PDF
