Since the mid-1980s, our understanding of nutrient limitation of oceanic primary production has radically changed. Mesoscale iron addition experiments (FeAXs) have unequivocally shown that iron ...supply limits production in one-third of the world ocean, where surface macronutrient concentrations are perennially high. The findings of these 12 FeAXs also reveal that iron supply exerts controls on the dynamics of plankton blooms, which in turn affect the biogeochemical cycles of carbon, nitrogen, silicon, and sulfur and ultimately influence the Earth climate system. However, extrapolation of the key results of FeAXs to regional and seasonal scales in some cases is limited because of differing modes of iron supply in FeAXs and in the modern and paleo-oceans. New research directions include quantification of the coupling of oceanic iron and carbon biogeochemistry.
Background. Klebsiella pneumoniae is an opportunistic pathogen and leading cause of hospital-associated infections. Intensive care unit (ICU) patients are particularly at risk. Klebsiella pneumoniae ...is part of the healthy human microbiome, providing a potential reservoir for infection. However, the frequency of gut colonization and its contribution to infections are not well characterized. Methods. We conducted a 1-year prospective cohort study in which 498 ICU patients were screened for rectal and throat carriage of K. pneumoniae shortly after admission. Klebsiella pneumoniae isolated from screening swabs and clinical diagnostic samples were characterized using whole genome sequencing and combined with epidemiological data to identify likely transmission events. Results. Klebsiella pneumoniae carriage frequencies were estimated at 6% (95% confidence interval CI, 3%–8%) among ICU patients admitted direct from the community, and 19% (95% CI, 14%–51%) among those with recent healthcare contact. Gut colonization on admission was significantly associated with subsequent infection (infection risk 16% vs 3%, odds ratio OR = 6.9, P < .001), and genome data indicated matching carriage and infection isolates in 80% of isolate pairs. Five likely transmission chains were identified, responsible for 12% of K. pneumoniae infections in ICU. In sum, 49% of K. pneumoniae infections were caused by the patients' own unique strain, and 48% of screened patients with infections were positive for prior colonization. Conclusions. These data confirm K. pneumoniae colonization is a significant risk factor for infection in ICU, and indicate ∼50% of K. pneumoniae infections result from patients' own microbiota. Screening for colonization on admission could limit risk of infection in the colonized patient and others.
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.
Cool main-sequence, subgiant, and red giant stars all show solar-like oscillations, pulsations that are excited and intrinsically damped by near-surface convection. Many overtones are typically ...excited to observable amplitudes, giving a rich spectrum of detectable modes. These modes provide a wealth of information on fundamental stellar properties. However, the radial velocity (RV) shifts induced by these oscillations can also be problematic when searching for low-mass, long-period planets; this is because their amplitudes are large enough to completely mask such minute planetary signals. Here we show how fine-tuning exposure times to the stellar parameters can help efficiently average out the solar-like, oscillation-induced shifts. To reduce the oscillation signal to the RV precision commensurate with an Earth analog, we find that for cool, low-mass stars (near spectral type K), the necessary exposure times may be as short as ∼4 minutes, while for hotter, higher-mass stars (near spectral type F, or slightly evolved), the required exposure times can be longer than 100 minutes. We provide guideline exposure durations required to suppress the total observed amplitude due to oscillations to a level of 0.1 m s−1, and a level corresponding to the Earth-analog reflex amplitude for the star. Owing to the intrinsic stochastic variability of the oscillations, we recommend in practice choosing short exposure durations at the telescope and then averaging over those exposures later, as guided by our predictions. To summarize, as we enter an era of 0.1 m s−1 instrumental precision, it is critical to tailor our observing strategies to the stellar properties.
ABSTRACT
High-resolution Doppler-resolved spectroscopy has opened up a new window into the atmospheres of both transiting and non-transiting exoplanets. Here, we present VLT/UVES observations of a ...transit of WASP-121b, an ‘ultra-hot’ Jupiter previously found to exhibit a temperature inversion and detections of multiple species at optical wavelengths. We present initial results using the blue arm of UVES (≈3700–5000 Å), recovering a clear signal of neutral Fe in the planet’s atmosphere at >8$\, \sigma$, which could contribute to (or even fully explain) the temperature inversion in the stratosphere. However, using standard cross-correlation methods, it is difficult to extract physical parameters such as temperature and abundances. Recent pioneering efforts have sought to develop likelihood ‘mappings’ that can be used to directly fit models to high-resolution data sets. We introduce a new framework that directly computes the likelihood of the model fit to the data, and can be used to explore the posterior distribution of parametrised model atmospheres via MCMC techniques. Our method also recovers the physical extent of the atmosphere, as well as account for time- and wavelength-dependent uncertainties. We measure a temperature of $3710^{+490}_{-510}$ K, indicating a higher temperature in the upper atmosphere when compared to low-resolution observations. We also show that the Fe i signal is physically separated from the exospheric Fe ii. However, the temperature measurements are highly degenerate with aerosol properties; detection of additional species, using more sophisticated atmospheric models, or combining these methods with low-resolution spectra should help break these degeneracies.
•We have assessed central Southern England for wind and solar energy suitability.•We apply a method with expert validation to two related types of renewable energy.•A high number of environmental ...constraints limit suitability for renewables.•The region is less suitable for wind energy generation than for solar developments.
As global growth in renewable energy projects accelerates, site identification will come to the forefront, where a key consideration is to minimise the environmental impact of the development. A large area of southern England (17,094km2) was assessed for suitability for wind and solar farm developments in three stages using geographic information systems. A multi-criteria decision making framework incorporating an analytical hierarchy process involving expert stakeholders was applied, which is a novel approach for this type of study. A binary constraint layer was created identifying entirely unsuitable locations. A factor layer was developed to indicate suitability in relation to a range of variables. Suitability layers for wind farm and solar farm development were then created covering the region. The environmental constraints used in the model accounted for over 60% of the study area for both wind and solar developments. Suitability for wind energy was generally low, with only 0.5km2 accounting for the ‘most suitable’ category. Solar suitability was higher overall; and a greater area (294km2) within the ‘most suitable’ category, suggesting the region is better suited for solar farm developments. Stakeholder input resulted in higher weightings for economic considerations for the solar model, prompting the most suitable areas to coincide with locations of the national grid connections. A sensitivity analysis indicated that model was generally reliable. This method can be used to assist appropriate site selection for onshore renewable energy projects across large geographical areas, helping to minimise their environmental impacts.
Aim
The goal of this European Society of ColoProctology project was to establish a multidisciplinary, international guideline for haemorrhoidal disease (HD) and to provide guidance on the most ...effective (surgical) treatment for patients with HD.
Methods
The development process consisted of six phases. In phase one we defined the scope of the guideline. The patient population included patients with all stages of haemorrhoids. The target group for the guideline was all practitioners treating patients with haemorrhoids and, in addition, healthcare workers and patients who desired information regarding the treatment management of HD. The guideline needed to address both the diagnosis of and the therapeutic modalities for HD. Phase two consisted of the compilation of the guideline development group (GDG). All clinical members needed to have affinity with the diagnosis and treatment of haemorrhoids. Further, attention was paid to the geographical distribution of the clinicians. Each GDG member identified at least one patient in their country who could read English to comment on the draft guideline. In phase three review questions were formulated, using a reversed process, starting with possible recommendations based on the GDG’s knowledge. In phase four a literature search was performed in MEDLINE (Ovid), PubMed, Embase (Ovid) and the Cochrane Database of Systematic Reviews. The search was focused on existing systematic reviews addressing each review question, supplemented by other studies published after the time frame covered by the systematic reviews. In phase five data of the included papers were extracted by the surgical resident (RT) and checked by the methodologist (JK) and the GDG. If needed, meta‐analysis of the systematic reviews was updated by the surgical resident and the methodologist using Review Manager. During phase six the GDG members decided what recommendations could be made based on the evidence found in the literature using GRADE.
Results
There were six sections: (i) symptoms, diagnosis and classification; (ii) basic treatment; (iii) outpatient procedures; (iv) surgical interventions; (v) special situations; (vi) other surgical techniques. Thirty‐four recommendations were formulated.
Conclusion
This international, multidisciplinary guideline provides an up to date and evidence based summary of the current knowledge of the management of HD and may serve as a useful guide for patients and clinicians.
Probing Cold Dense Nuclear Matter Subedi, R; Shneor, R; Monaghan, P ...
Science (American Association for the Advancement of Science),
06/2008, Letnik:
320, Številka:
5882
Journal Article
Recenzirano
Odprti dostop
The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, in which a proton is knocked out of the nucleus with high-momentum transfer and high missing ...momentum, show that in carbon-12 the neutron-proton pairs are nearly 20 times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.
Klebsiella pneumoniae is a major cause of opportunistic healthcare-associated infections, which are increasingly complicated by the presence of extended-spectrum beta-lactamases (ESBLs) and ...carbapenem resistance. We conducted a year-long prospective surveillance study of K. pneumoniae clinical isolates in hospital patients. Whole-genome sequence (WGS) data reveals a diverse pathogen population, including other species within the K. pneumoniae species complex (18%). Several infections were caused by K. variicola/K. pneumoniae hybrids, one of which shows evidence of nosocomial transmission. A wide range of antimicrobial resistance (AMR) phenotypes are observed, and diverse genetic mechanisms identified (mainly plasmid-borne genes). ESBLs are correlated with presence of other acquired AMR genes (median n = 10). Bacterial genomic features associated with nosocomial onset are ESBLs (OR 2.34, p = 0.015) and rhamnose-positive capsules (OR 3.12, p < 0.001). Virulence plasmid-encoded features (aerobactin, hypermucoidy) are observed at low-prevalence (<3%), mostly in community-onset cases. WGS-confirmed nosocomial transmission is implicated in just 10% of cases, but strongly associated with ESBLs (OR 21, p < 1 × 10
). We estimate 28% risk of onward nosocomial transmission for ESBL-positive strains vs 1.7% for ESBL-negative strains. These data indicate that K. pneumoniae infections in hospitalised patients are due largely to opportunistic infections with diverse strains, with an additional burden from nosocomially-transmitted AMR strains and community-acquired hypervirulent strains.
Livers retrieved after circulatory death are associated with an increased incidence of primary nonfunction, early allograft dysfunction, and biliary strictures. The authors report a case of ...preimplant normothermic perfusion of a suboptimal liver from a 57‐year‐old donor after circulatory death who had been hospitalized for 9 days; predonation alanine transaminase level was 63 IU/L, and the period from withdrawal of life‐supporting treatment to circulatory arrest was 150 minutes. After 5 hours of static cold storage, the liver was subject to normothermic machine perfusion with a plasma‐free red cell–based perfusate. Perfusate lactate level fell from 7.2 to 0.3 mmol/L within 74 minutes of ex situ perfusion, at which point perfusate alanine transaminase level was 1152 IU/L and urea concentration was 9.4 mmol/L. After 132 minutes, normothermic perfusion was stopped and implantation begun. After transplantation, the patient made an uneventful recovery and was discharged on day 8; liver biochemistry was normal by day 19 and has remained normal thereafter. Donor common bile duct excised at implantation showed preservation of peribiliary glands, and cholangiography 6 months posttransplantation showed no evidence of cholangiopathy. Preimplant ex situ normothermic perfusion of the liver appears to be a promising way to evaluate a marginal liver before transplantation and may modify the response to ischemia.
The authors report a liver transplant where ex situ normothermic machine perfusion was used to reduce cold ischemia and permit functional assessment of a donation after circulatory death liver before implantation.
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