434 research outputs found
Fire in the Heart: A Characterization of the High Kinetic Temperatures and Heating Sources in the Nucleus of NGC253
The nuclear starburst within the central (
pc; pc) of NGC253 has been extensively studied as
a prototype for the starburst phase in galactic evolution. Atacama Large
Millimeter/submillimeter Array (ALMA) imaging within receiver Bands 6 and 7
have been used to investigate the dense gas structure, kinetic temperature, and
heating processes which drive the NGC253 starburst. Twenty-nine transitions
from fifteen molecular species/isotopologues have been identified and imaged at
to resolution, allowing for the
identification of five of the previously-studied giant molecular clouds (GMCs)
within the central molecular zone (CMZ) of NGC253. Ten transitions from the
formaldehyde (HCO) molecule have been used to derive the kinetic
temperature within the to
dense-gas structures imaged. On scales we measure K, while on size scales we measure K. These kinetic temperature measurements further delineate the
association between potential sources of dense gas heating. We have
investigated potential heating sources by comparing our measurements to models
which predict the physical conditions associated with dense molecular clouds
that possess a variety of heating mechanisms. This comparison has been
supplemented with tracers of recently-formed massive stars (Br) and
shocks ([FeII]). Derived molecular column densities point to a
radially-decreasing abundance of molecules with sensitivity to cosmic ray and
mechanical heating within the NGC253 CMZ. These measurements are consistent
with radio spectral index calculations which suggest a higher concentration of
cosmic ray producing supernova remnants within the central 10 pc of NGC253.Comment: 60 pages, 25 figures (whew!), Accepted for publication in ApJ, Latest
version includes minor corrections following proof submissio
Accurate distance control between a probe and a surface using a microcantilever
We demonstrate a method to accurately control the distance between a custom
probe and a sample on a {\mu}m to nm scale. The method relies on the
closed-loop feedback on the angular deflection of an in-contact AFM
microcantilever. High performance in stability and accuracy is achieved in this
method by taking advantage of the small mechanical feedback path between
surface and probe. We describe how internal error sources that find their
origin in the microcantilever and feedback can be minimized to achieve an
accurate and precise control up to 3 nm. In particular, we investigated how
hysteresis effects in the feedback caused by friction forces between tip and
substrate, can be minimized. By applying a short calibration procedure,
distance control from contact to several micrometers probe-sample distance can
be obtained with an absolute nanometer-scale accuracy. The method presented is
compatible with any probe that can be fixed on a microcantilever chip and can
be easily built into existing AFM systems
ALMA Observations of the Physical and Chemical Conditions in Centaurus A
Centaurus A, with its gas-rich elliptical host galaxy, NGC 5128, is the
nearest radio galaxy at a distance of 3.8 Mpc. Its proximity allows us to study
the interaction between an active galactic nucleus, radio jets, and molecular
gas in great detail. We present ALMA observations of low J transitions of three
CO isotopologues, HCN, HCO, HNC, CN, and CCH toward the inner projected
500 pc of NGC 5128. Our observations resolve physical sizes down to 40 pc. By
observing multiple chemical probes, we determine the physical and chemical
conditions of the nuclear interstellar medium of NGC 5128. This region contains
molecular arms associated with the dust lanes and a circumnuclear disk (CND)
interior to the molecular arms. The CND is approximately 400 pc by 200 pc and
appears to be chemically distinct from the molecular arms. It is dominated by
dense gas tracers while the molecular arms are dominated by CO and its
rare isotopologues. The CND has a higher temperature, elevated CN/HCN and
HCN/HNC intensity ratios, and much weaker CO and CO emission than
the molecular arms. This suggests an influence from the AGN on the CND
molecular gas. There is also absorption against the AGN with a low velocity
complex near the systemic velocity and a high velocity complex shifted by about
60 km s. We find similar chemical properties between the CND in emission
and both the low and high velocity absorption complexes implying that both
likely originate from the CND. If the HV complex does originate in the CND,
then that gas would correspond to gas falling toward the supermassive black
hole
Outcomes in Dutch DPP6 risk haplotype for familial idiopathic ventricular fibrillation:a focused update
Background: The genetic risk haplotype DPP6 has been linked to familial idiopathic ventricular fibrillation (IVF), but the associated long-term outcomes are unknown. Methods: DPP6 risk haplotype-positive family members (DPP6 cases) and their risk haplotype-negative relatives (DPP6 controls) were included. Clinical follow-up data were collected through March 2023. Implantable cardioverter-defibrillator (ICD) indication was divided in primary or secondary prevention. Cumulative survival and event rates were calculated. Results: We included 327 DPP6 cases and 315 DPP6 controls. Median follow-up time was 9 years (interquartile range: 4–12). Of the DPP6 cases, 129 (39%) reached the composite endpoint of appropriate ICD shock, sudden cardiac arrest or death, at a median age of 45 years (range: 15–97). Median overall survival was 83 years and 87 years for DPP6 cases and DPP6 controls, respectively (p < 0.001). In DPP6 cases, median overall survival was shorter for males (74 years) than females (85 years) (p < 0.001). Of the DPP6 cases, 97 (30%) died, at a median age of 50 years. With a prophylactic ICD implantation advise based on risk haplotype, sex and age, 137 (42%) of DPP6 cases received an ICD, for primary prevention (n = 109) or secondary prevention (n = 28). In the primary prevention subgroup, 10 patients experienced a total of 34 appropriate ICD shocks, and there were no deaths during follow-up. DPP6 cases with a secondary prevention ICD experienced a total of 231 appropriate ICD shocks.Conclusion: Patients with the DPP6 risk haplotype, particularly males, are at an increased risk of IVF and sudden cardiac death. Using a risk stratification approach based on risk haplotype, sex and age, a substantial proportion of patients with a primary prevention ICD experienced appropriate ICD shocks, showing the benefit of prophylactic ICD implantation with this strategy.</p
Low rate of cardiac events in first-degree relatives of diagnosis-negative young sudden unexplained death syndrome victims during follow-up
BACKGROUND: Sudden unexplained death syndrome (SUDS) in young individuals often results from inherited cardiac disease. Accordingly, comprehensive examination in surviving first-degree relatives unmasks such disease in approximately 35% of the families. It is unknown whether individuals from diagnosis-negative families are at risk of developing manifest disease or cardiac events during follow-up.OBJECTIVE: This study aimed to study the prognosis of first-degree relatives of young SUDS victims, in whom the initial cardiologic and genetic examination did not lead to a diagnosis.METHODS: We retrieved vital status of surviving first-degree relatives from 83 diagnosis-negative families who presented to our cardiogenetics department between 1996 and 2009 because of SUDS in ≥1 relatives aged 1-50 years. Moreover, we contacted relatives who previously visited our center for detailed information.RESULTS: We obtained detailed information (median follow-up 6.6 years; interquartile range 4.7-9.6 years) in 340 of 417 first-degree relatives (81.5%) from 77 of 83 families (92.8%). Vital status, available in 405 relatives (97.1%), showed that 20 relatives (4.9%) died during follow-up, including 1 natural death before the age of 50. This girl belonged to a family with multiple cases of idiopathic ventricular fibrillation and SUDS, including another successfully resuscitated sibling during follow-up. Two hundred thirty-four of 340 first-degree relatives (68.8%) underwent cardiologic examination. Of these, 76 (32.5%) were reevaluated. Inherited cardiac disease was diagnosed in 3 families (3.6%).CONCLUSION: In first-degree relatives of young SUDS victims with no manifest abnormalities during the initial examination, the risk of developing manifest inherited cardiac disease or cardiac events during follow-up is low. This does not apply to families with obvious familial SUDS.</p
Trace gas/aerosol boundary concentrations and their impacts on continental-scale AQMEII modeling domains
Copyright 2011 Elsevier B.V., All rights reserved.Over twenty modeling groups are participating in the Air Quality Model Evaluation International Initiative (AQMEII) in which a variety of mesoscale photochemical and aerosol air quality modeling systems are being applied to continental-scale domains in North America and Europe for 2006 full-year simulations for model inter-comparisons and evaluations. To better understand the reasons for differences in model results among these participating groups, each group was asked to use the same source of emissions and boundary concentration data for their simulations. This paper describes the development and application of the boundary concentration data for this AQMEII modeling exercise. The European project known as GEMS (Global and regional Earth-system Monitoring using Satellite and in-situ data) has produced global-scale re-analyses of air quality for several years, including 2006 (http://gems.ecmwf.int). The GEMS trace gas and aerosol data were made available at 3-hourly intervals on a regular latitude/longitude grid of approximately 1.9° resolution within 2 "cut-outs" from the global model domain. One cut-out was centered over North America and the other over Europe, covering sufficient spatial domain for each modeling group to extract the necessary time- and space-varying (horizontal and vertical) concentrations for their mesoscale model boundaries. Examples of the impact of these boundary concentrations on the AQMEII continental simulations are presented to quantify the sensitivity of the simulations to boundary concentrations. In addition, some participating groups were not able to use the GEMS data and instead relied upon other sources for their boundary concentration specifications. These are noted, and the contrasting impacts of other data sources for boundary data are presented. How one specifies four-dimensional boundary concentrations for mesoscale air quality simulations can have a profound impact on the model results, and hence, this aspect of data preparation must be performed with considerable care.Peer reviewedFinal Accepted Versio
Reduced Calcium Signaling Is Associated With Severe Graft-Versus-Host Disease: Results From Preclinical Models and From a Prospective EBMT Study
Despite its involvement in various immune functions, including the allogeneic activation of T-lymphocytes, the relevance of calcium (Ca2+) for GVHD pathobiology is largely unknown. To elucidate a potential association between Ca(2+)and GVHD, we analyzed Ca2+-sensing G-protein coupled receptor 6a (GPRC6a) signaling in preclinical GVHD models and conducted a prospective EBMT study on Ca(2+)serum levels prior alloSCT including 363 matched sibling allogeneic peripheral blood stem cell transplantations (alloSCTs). In experimental models, we found decreasedGprc6aexpression during intestinal GVHD. GPRC6a deficient alloSCT recipients had higher clinical and histopathological GVHD scores leading to increased mortality. As possible underlying mechanism, we found increased antigen presentation potential in GPRC6a(-/-)alloSCT recipients demonstrated by higher proliferation rates of T-lymphocytes. In patients with low Ca(2+)serum levels (≤ median 2.2 mmol/l) before alloSCT, we found a higher incidence of acute GVHD grades II-IV (HR = 2.3 Cl = 1.45-3.85p= 0.0006), severe acute GVHD grades III-IV (HR = 3.3 CI = 1.59-7.14,p= 0.002) and extensive chronic GVHD (HR = 2.0 Cl = 1.04-3.85p= 0.04). In conclusion, experimental and clinical data suggest an association of reduced Ca(2+)signaling with increased severity of GVHD. Future areas of interest include the in depth analysis of involved molecular pathways and the investigation of Ca(2+)signaling as a therapeutic target during GVHD
Use of busulfan in conditioning for allogeneic hematopoietic stem cell transplantation in adults : a survey by the Transplant Complications Working Party of the EBMT
A survey was carried out among EBMT centers about the use of busulfan for conditioning in allogeneic stem cell transplantation. Of 109 responding centers, 106 used busulfan for conditioning, 102 in conventional myeloablative doses, and 93 in reduced doses (RIC). The route of administration was mostly intravenous, but similar to 10% of the centers gave the drug orally. The number of doses in i.v. administration varied and was in myeloablative conditioning mostly one (50 centers) or four (43 centers) doses a day. Seventeen of the 106 centers used pharmacokinetics for dose adjustment in myeloablative conditioning, nine in RIC. The details of pharmacokinetic monitoring varied markedly. Three quarters of the centers reported adjusting the dose based on obesity in myeloablative conditioning and about 60% in RIC. The most common method for dose calculation was ideal body weight + 0.25 x (actual body weight - ideal body weight). In conclusion, the present survey showed marked heterogeneity in the current practices of busulfan administration for conditioning. The impact of the heterogeneity is not well known. Due to this and the scarcity of support from controlled clinical studies, no clear guidelines can be presented, but some prevailing policies to be recommended were identified.Peer reviewe
From abstract to impact in cardiovascular research: factors predicting publication and citation
Aims Through a 4-year follow-up of the abstracts submitted to the European Society of Cardiology Congress in 2006, we aimed at identifying factors predicting high-quality research, appraising the quality of the peer review and editorial processes, and thereby revealing potential ways to improve future research, peer review, and editorial work. Methods and results All abstracts submitted in 2006 were assessed for acceptance, presentation format, and average reviewer rating. Accepted and rejected studies were followed for 4 years. Multivariate regression analyses of a representative selection of 10% of all abstracts (n= 1002) were performed to identify factors predicting acceptance, subsequent publication, and citation. A total of 10 020 abstracts were submitted, 3104 (31%) were accepted for poster, and 701 (7%) for oral presentation. At Congress level, basic research, a patient number ≥ 100, and prospective study design were identified as independent predictors of acceptance. These factors differed from those predicting full-text publication, which included academic affiliation. The single parameter predicting frequent citation was study design with randomized controlled trials reaching the highest citation rates. The publication rate of accepted studies was 38%, whereas only 24% of rejected studies were published. Among published studies, those accepted at the Congress received higher citation rates than rejected ones. Conclusions Research of high quality was determined by study design and largely identified at Congress level through blinded peer review. The scientometric follow-up revealed a marked disparity between predictors of full-text publication and those predicting citation or acceptance at the Congres
In situ tropical peatland fire emission factors and their variability, as determined by field measurements in Peninsula Malaysia.
Fires in tropical peatlands account for >25% of estimated total greenhouse gas emissions from deforestation and degradation. Despite significant global and regional impacts, our understanding of specific gaseous fire emission factors (EFs) from tropical peat burning is limited to a handful of studies. Furthermore, there is substantial variability in EFs between sampled fires and/or studies. For example, methane EFs vary by 91% between studies.
Here we present new fire EFs for the tropical peatland ecosystem; the first EFs measured for Malaysian peatlands, and only the second comprehensive study of EFs in this crucial environment. During August 2015 (under El Niño conditions) and July 2016, we embarked on field campaigns to measure gaseous emissions at multiple peatland fires burning on deforested land in Southeast Pahang (2015) and oil palm plantations in North Selangor (2016), Peninsula Malaysia. Gaseous emissions were measured using open-path Fourier transform infrared spectroscopy. The IR spectra were used to retrieve mole fractions of twelve different gases present within the smoke (including carbon dioxide and methane), and these measurements used to calculate EFs. Peat samples were taken at each burn site for physicochemical analysis and to explore possible relationships between specific physicochemical properties and fire EFs. Here we present the first evidence to indicate that substrate bulk density affects methane fire EFs reported here. This novel explanation of inter-plume, within-biome variability should be considered by those undertaking greenhouse gas accounting and haze forecasting in this region, and is of importance to peatland management, particularly with respect to artificial compaction
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