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Gamma-ray burst host galaxies are deficient in molecular gas, and show anomalous metal-poor regions close to GRB positions. Using recent Australia Telescope Compact Array (ATCA) Hi observations we show that they have substantial atomic gas reservoirs. This suggests that star formation in these galaxies may be fuelled by recent inflow of metal-poor atomic gas. While this process is debated, it can happen in low-metallicity gas near the onset of star formation because gas cooling (necessary for star formation) is faster than the Hi-to-H2 conversion.
Impaired emotion regulation may underlie exaggerated emotional reactivity in patients with obsessive compulsive disorder (OCD), yet instructed emotion regulation has never been studied in the disorder.
This study aimed to assess the neural correlates of emotion processing and regulation in 43 medication-free OCD patients and 38 matched healthy controls, and additionally test if these can be modulated by stimulatory (patients) and inhibitory (controls) repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex (dlPFC). Participants performed an emotion regulation task during functional magnetic resonance imaging before and after a single session of randomly assigned real or sham rTMS. Effect of group and rTMS were assessed on self-reported distress ratings and brain activity in frontal-limbic regions of interest.
Patients had higher distress ratings than controls during emotion provocation, but similar rates of distress reduction after voluntary emotion regulation. OCD patients compared with controls showed altered amygdala responsiveness during symptom provocation and diminished left dlPFC activity and frontal-amygdala connectivity during emotion regulation. Real v. sham dlPFC stimulation differentially modulated frontal-amygdala connectivity during emotion regulation in OCD patients.
We propose that the increased emotional reactivity in OCD may be due to a deficit in emotion regulation caused by a failure of cognitive control exerted by the dorsal frontal cortex. Modulatory rTMS over the left dlPFC may influence automatic emotion regulation capabilities by influencing frontal-limbic connectivity.
We study hydrogenated amorphous silicon germanium (a-SiGe:H) deposited by HWCVD for the use as low band gap absorber in multijunction junction solar cells. We deposited layers with Tauc optical band gaps of 1.21 to 1.56 eV and studied the hydrogen bonding with FTIR for layers that were deposited at several reaction pressures. For our reaction conditions, we found an optimal reaction pressure of 38 µbar. The material that is obtained under these conditions does not meet all device quality requirements for a-SiGe:H, which is, as we hypothesize, caused by the presence of He that is used to dilute the GeH4 source gas. We present an initial single junction n-i-p solar cell with a Tauc optical band gap of 1.45 eV and a short circuit current density of 18.7 mA/cm2.
Results from a large, multi-J CO, 13CO, and HCN line survey of Luminous Infrared Galaxies (LIRGs: LIR≥ 1010 L⊙) in the local Universe (z≤0.1), complemented by CO J=4–3 up to J=13–12 observations from the Herschel Space Observatory (HSO), paints a new picture for the average conditions of the molecular gas of the most luminous of these galaxies with turbulence and/or large cosmic ray (CR) energy densities UCR rather than far-UV/optical photons from star-forming sites as the dominant heating sources. Especially in ULIRGs (LIR>1012 L⊙) the Photon Dominated Regions (PDRs) can encompass at most a few % of their molecular gas mass while the large UCR∼ 103 UCR, Galaxy, and the strong turbulence in these merger/starbursts, can volumetrically heat much of their molecular gas to Tkin∼ (100-200) K, unhindered by the high dust extinctions. Moreover the strong supersonic turbulence in ULIRGs relocates much of their molecular gas at much higher average densities (≥104 cm−3) than in isolated spirals (∼ 102–103 cm−3). This renders low-J CO lines incapable of constraining the properties of the bulk of the molecular gas in ULIRGs, with substantial and systematic underestimates of its mass possible when only such lines are used. Finally a comparative study of multi-J HCN lines and CO SLEDs from J=1–0 up to J=13–12 of NGC 6240 and Arp 193 offers a clear example of two merger/starbursts whose similar low-J CO SLEDs, and LIR/LCO,1−0 and LHCN, 1−0/LCO,1-0 ratios (proxies of the so-called SF efficiency and dense gas mass fraction), yield no indications about their strongly diverging CO SLEDs beyond J=4–3, and ultimately the different physical conditions in their molecular ISM. The much larger sensitivity of ALMA and its excellent site in the Atacama desert now allows the observations necessary to assess the dominant energy sources of the molecular gas and its mass in LIRGs without depending on the low-J CO lines.
Supernovae play an integral role in the feedback of processed material back into the interstellar medium (ISM) of galaxies and are responsible for most of the chemical enrichment of the universe. The rate of supernovae can also reveal the star formation histories. In a sample of 11 nearby galaxies observed with SINFONI, a strong linear correlation between [FeII]1.26 luminosity and Starburst 99-derived supernova rate is found on a pixel-pixel basis. In the very nearby archetypal starburst galaxy NGC 253, the excitation of molecular gas is a subject of debate. Using the correlation between [FeII] and supernova rate, we can determine if supernovae can account for the excitation of the bright observed near-infrared H2 emission.
The aim of this study was to determine the nationwide prevalence of smear-positive tuberculosis (TB) in Bangladesh. A multi-stage cluster survey of a random sample of persons aged ⩾15 years was included in 40 clusters (20 urban, 20 rural). Two sputum samples were collected from study participants and tested initially by fluorescence microscopy and confirmed by the Ziehl–Neelsen method. The crude and adjusted prevalence rates and 95% confidence intervals (CIs) were calculated using standard methods. A total of 33 new smear-positive TB cases were detected among 52 098 individuals who participated in the study. The average participation rate was over 80%. The overall crude prevalence of new smear-positive TB in persons aged ⩾15 years was estimated as 63·3/100 000 (95% CI 43·6–88·9) and the adjusted prevalence was 79·4/100 000 (95% CI 47·1–133·8). TB prevalence was higher in males (n=24) and in rural areas (n=20). The prevalence was highest in the 55–64 years age group (201/100 000) and lowest in 15–24 years age group (43·0/100 000). The prevalence was higher in persons with no education (138·6/100 000, 95% CI 78·4–245·0). The overall prevalence of smear-positive TB was significantly lower than the prevalence estimate of the previous nationwide survey in Bangladesh in 1987–1988 (870/100 000).
One challenge for the environmental assessment of agricultural systems is to progress from estimating whether one farming system has fewer impacts than another to estimating whether or not it can be considered environmentally sustainable. To this end, we developed reference values (RVs) of farm emissions or energy use per hectare that defined hypothetical sustainability thresholds in each of three impact categories: climate change, water-quality degradation and non-renewable energy use. We applied one RV per category to the potential impacts (estimated by life-cycle assessment) of 45 French dairy farms to identify farms below RVs in each impact category and then evaluated their management and production characteristics. Seventeen of the 45 farms lie below at least one of the three RVs. Groups of farms below RVs had a higher percentage of organic farms, larger mean usable agricultural area, longer mean pasture residence time and lower mean inputs of concentrate feed and nitrogen than those above the same RVs. In consequence, the groups below RVs also tended to have lower mean milk production per cow and per hectare. All milk production systems can move toward environmental sustainability even though, according to production mode and intensity, some potential impacts are easier to reduce than others. Most farms were unable to attain the lowest RVs, suggesting that policy-makers may need to consider less ambitious RVs for existing agricultural systems. Otherwise, the distance between normative RVs and indicator values of dairy farms suggest that production and consumption of agricultural products will need to change if sustainability goals do not.
Here we present the results of a 3 mm survey of 23 galaxies, obtained with the EMIR
receiver at the IRAM 30 m telescope. Emission of the main molecular species is compared
with existing chemical models, in order to find and test molecular signatures of galaxy
evolution and to compare them to IR evolutionary tracers.
Seed predation is an important component of seed mortality of weeds in agro-ecosystems, but the agronomic use and management of this natural weed suppression is hampered by a lack of insight in the underlying ecological processes. In this paper, we investigate whether and how spatial and temporal variation in activity-density of granivorous ground beetles (Coleoptera: Carabidae) results in a corresponding pattern of seed predation. Activity-density of carabids was measured by using pitfall traps in two organic winter wheat fields from March to July 2004. Predation of seeds (Capsella bursa-pastoris, Lamium amplexicaule, Poa annua and Stellaria media) was assessed using seed cards at the same sites and times. As measured by pitfall traps, carabids were the dominant group of insects that had access to the seed cards. In the field, predation of the four different species of seed was in the order: C. bursa-pastoris>P. annua>S. media>L. amplexicaule; and this order of preference was confirmed in the laboratory using the dominant species of carabid. On average, seed predation was higher in the field interior compared to the edge, whereas catches of carabids were highest near the edge. Weeks with elevated seed predation did not concur with high activity-density of carabids. Thus, patterns of spatial and temporal variation in seed predation were not matched by similar patterns in the abundance of granivorous carabid beetles. The lack of correspondence is ascribed to effects of confounding factors, such as weather, the background density of seeds, the composition of the carabid community, and the phenology and physiological state of the beetles. Our results show that differences in seed loss among weed species may be predicted from laboratory trials on preference. However, predator activity-density, as measured in pitfall traps, is an insufficient predictor of seed predation over time and space within a field.
We explore the physical characteristics of young stellar clusters in the Antennae by combining recent ground- and space-based mid-infrared observations with a newly developed set of diagnostic diagrams. Spitzer data give an overview of the star-forming regions extending over hundreds of parsecs, showing a dominant diffuse ISM component with a density of 102 cm−3 plus a small fraction of very compact material (106 cm−3). With its higher spatial resolution VISIR gives a close-up view of the latter component. Its emission line ratios suggest that these regions are fundamentally different from local star-forming regions. Instead of having small isolated UCHII regions, as in local star-forming regions, the average density of the medium of the whole region falls in the (ultra)compact regime, exceeding 104 cm−3 over tens of parsecs.
Observations and interpretation of extragalactic rotational and rovibrational H2 emission are reviewed. Direct observations of H2 lines do not trace bulk H2 mass, but excitation rate. As such, the H2 lines are unique diagnostics, if the excitation mechanism can be determined, which generally requires high-quality spectroscopy and suitable additional data. The diagnostic power of the H2 lines is illustrated by two cases studies: H2 purely rotational line emission from the disk of the nearby spiral galaxy NGC891 and high resolution imaging and spectroscopy of H2 vibrational line emission from the luminous merger NGC6240.
Direct observations of H2 emission from external galaxies have become standard practice in the past decade through the revolution in ground-based near-infrared instrumentation. As a result, the near-infrared H2 rovibrational lines are now readily detectable throughout the local universe (e.g., Moorwood & Oliva 1988, 1990; Puxley et al. 1988, 1990; Goldader et al. 1995, 1997; Vanzi et al. 1998). More recently, the Short Wavelength Spectrograph (SWS) on the Infrared Space Observatory (ISO) has for the first time allowed detection of the purely rotational H2 lines in the mid-infrared spectral regime. For instance, the first detection (outside the solar system) of the H2S(0) line at 28.21 µm was reported by Valentijn et al. (1996) from the star forming nucleus of the nearby spiral galaxy NGC 6946.
Aggleton & Brown propose that familiarity-based
recognition depends on a perirhinal-medial dorsal thalamic system.
However, connections between these structures are sparse or absent. In
contrast, the perirhinal cortex is connected to midline/intralaminar
nuclei. In a human, a lesion in this thalamic domain, sparing the
medial dorsal nucleus, impaired familiarity-based recognition while
sparing recollective-based recognition. It is thus more likely that
the intralaminar/midline nuclei are involved in recognition.
We discuss the use of seeing-limited near-IR spectroscopic imaging combined with high resolution millimeter and submillimeter wave observations, as a diagnostic in the study of the nuclear interstellar medium in starburst galaxies and active galactic nuclei. As an example, recent near-IR spectroscopic imaging of the starburst galaxy NGC 253 is analyzed. It is shown that the central ~ 100 pc of NGC 253 contains a number of giant star forming complexes, the stellar content of which is at least as large as that of the 30 Dor region in the LMC. We suggest the use of the [FeII]/Brγ ratio as an approximate age indicator for such complexes. The warm component of the nuclear molecular medium in NGC 253 detected in submillimeter CO spectra and in near-IR rovibrational lines of H2 is probably heated by stellar UV radiation or slow shocks in star forming regions, rather than by supernova remnant shocks. There are indications that molecular material is being removed from the nuclear region by the “superwind” observed in optical emission lines.
A series of hydrogenated amorphous silicon carbide (a-Si1–xCx:H) films was deposited by rf glow discharge deposition using various pressures, electrode spacings and hydrogen dilution ratios. We found that improvement of the structure by hydrogen dilution is more effective when a large electrode spacing is applied. In the case of undiluted a-SiC:H, the product of pressure and electrode spacing appears to be the important parameter. Dilution causes an increase of the photoconductivity. The band gap decreases but increases again for highly diluted samples. A striking result is that the Fourier transform infra-red spectroscopy (FTIR) bands assigned to CHX and SiHx increase upon dilution when a small electrode spacing is applied, although the hydrogen content is reduced. It is shown that this is due to an increase of the density of the films and to an increase of the amount of carbon built into the bulk instead of into voids. The combination of decreasing hydrogen content, void fraction and increasing amount of carbon atoms into the bulk explains the behaviour of the photoconductivity and band gap as a function of H2 dilution.
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