Ancient Geodynamics and Global-Scale Hydrology on Mars Phillips, Roger J.; Zuber, Maria T.; Solomon, Sean C. ...
Science (American Association for the Advancement of Science),
03/2001, Letnik:
291, Številka:
5513
Journal Article
Recenzirano
Loading of the lithosphere of Mars by the Tharsis rise explains much of the global shape and long-wavelength gravity field of the planet, including a ring of negative gravity anomalies and a ...topographic trough around Tharsis, as well as gravity anomaly and topographic highs centered in Arabia Terra and extending northward toward Utopia. The Tharsis-induced trough and antipodal high were largely in place by the end of the Noachian Epoch and exerted control on the location and orientation of valley networks. The release of carbon dioxide and water accompanying the emplacement of ∼ 3 × 108cubic kilometers of Tharsis magmas may have sustained a warmer climate than at present, enabling the formation of ancient valley networks and fluvial landscape denudation in and adjacent to the large-scale trough.
H₂O at the Phoenix Landing Site Smith, P.H; Tamppari, L.K; Arvidson, R.E ...
Science (American Association for the Advancement of Science),
07/2009, Letnik:
325, Številka:
5936
Journal Article
Recenzirano
The Phoenix mission investigated patterned ground and weather in the northern arctic region of Mars for 5 months starting 25 May 2008 (solar longitude between 76.5° and 148°). A shallow ice table was ...uncovered by the robotic arm in the center and edge of a nearby polygon at depths of 5 to 18 centimeters. In late summer, snowfall and frost blanketed the surface at night; H₂O ice and vapor constantly interacted with the soil. The soil was alkaline (pH = 7.7) and contained CaCO₃, aqueous minerals, and salts up to several weight percent in the indurated surface soil. Their formation likely required the presence of water.
Colistin is used against multi-drug resistant pathogens, yet resistance emerges through dissemination of plasmid-mediated genes (mcr) or chromosomal mutation of genes involved in lipopolysaccharide ...synthesis (i.e. mgrB, phoPQ, pmrCAB). Phenotypic susceptibility testing is challenging due to poor diffusion of colistin in agar media, leading to an underestimation of resistance. Performance of five phenotypic approaches was compared in the context of different molecular mechanisms of resistance. We evaluated Vitek 2® (bioMérieux, AST N242), Colistin MIC Test Strip (Liofilchem Diagnostici), UMIC (Biocentric), and Rapid Polymyxin™ NP test (ELITechGroup) against the standard broth microdilution (BMD) method. We used whole genome sequencing (WGS) to infer molecular resistance mechanisms. We analysed 97 Enterobacterales and non-fermenting bacterial isolates, largely clinical isolates collected up to 2018. Data was analysed by comparing susceptibility categories (susceptible or resistant) and minimal inhibitory concentrations (MIC). Susceptibility category concordance is the percentage of test results sharing the same category to BMD. MIC concordance was calculated similarly but considering ±1 MIC titre error range. We determined genomic diversity by core genome multi locus sequencing typing (cgMLST) and identified putative antimicrobial resistance genes using NCBI and CARD databases, and manual annotation.
Of 97 isolates, 54 (56%) were resistant with standard BMD. Highest susceptibility category concordance was achieved by Rapid Polymyxin™ NP (98.8%) followed by UMIC (97.9%), Colistin E-test MIC strip (96.9%) and Vitek 2® (95.6%). Highest MIC concordance was achieved by UMIC (80.4%), followed by Vitek 2® (72.5%) and Colistin E-test MIC strip (62.9%). Among resistant isolates, 23/54 (43%) were intrinsically resistant to colistin, whereas 31/54 (57%) isolates had acquired colistin resistance. Of these, mcr-1 was detected in four isolates and mcr-2 in one isolate. Non-synonymous mutations in mgrB, phoQ, pmrA, pmrB, and pmrC genes were encountered in Klebsiella pneumoniae, Escherichia coli, and Acinetobacter bereziniae resistant isolates. Mutations found in mgrB and pmrB were only identified in isolates exhibiting MICs of ≥16 mg/L.
The Rapid Polymyxin™ NP test showed highest categorical concordance and the UMIC test provided MIC values with high concordance to BMD. We found colistin resistance in diverse species occurred predominantly through spontaneous chromosomal mutation rather than plasmid-mediated resistance.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
We report the discovery of seven new Galactic pulsars with the Canadian Hydrogen Intensity Mapping Experiment’s Fast Radio Burst (CHIME/FRB) backend. These sources were first identified via ...single pulses in CHIME/FRB, then followed up with CHIME/Pulsar. Four sources appear to be rotating radio transients, pulsar-like sources with occasional single-pulse emission with an underlying periodicity. Of those four sources, three have detected periods ranging from 220 ms to 2.726 s. Three sources have more persistent but still intermittent emission and are likely intermittent or nulling pulsars. We have determined phase-coherent timing solutions for the latter two. These seven sources are the first discovery of previously unknown Galactic sources with CHIME/FRB and highlight the potential of fast radio burst detection instruments to search for intermittent Galactic radio sources.
Summary Background In developing countries, mortality in children with very severe pneumonia is high, even with the provision of appropriate antibiotics, standard oxygen therapy, and other supportive ...care. We assessed whether oxygen therapy delivered by bubble continuous positive airway pressure (CPAP) improved outcomes compared with standard low-flow and high-flow oxygen therapies. Methods This open, randomised, controlled trial took place in Dhaka Hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh. We randomly assigned children younger than 5 years with severe pneumonia and hypoxaemia to receive oxygen therapy by either bubble CPAP (5 L/min starting at a CPAP level of 5 cm H2 O), standard low-flow nasal cannula (2 L/min), or high-flow nasal cannula (2 L/kg per min up to the maximum of 12 L/min). Randomisation was done with use of the permuted block methods (block size of 15 patients) and Fisher and Yates tables of random permutations. The primary outcome was treatment failure (ie, clinical failure, intubation and mechanical ventilation, death, or termination of hospital stay against medical advice) after more than 1 h of treatment. Primary and safety analyses were by intention to treat. We did two interim analyses and stopped the trial after the second interim analysis on Aug 3, 2013, as directed by the data safety and monitoring board. This trial is registered at ClinicalTrials.gov , number NCT01396759. Findings Between Aug 4, 2011, and July 17, 2013, 225 eligible children were recruited. We randomly allocated 79 (35%) children to receive oxygen therapy by bubble CPAP, 67 (30%) to low-flow oxygen therapy, and 79 (35%) to high-flow oxygen therapy. Treatment failed for 31 (14%) children, of whom five (6%) had received bubble CPAP, 16 (24%) had received low-flow oxygen therapy, and ten (13%) had received high-flow oxygen therapy. Significantly fewer children in the bubble CPAP group had treatment failure than in the low-flow oxygen therapy group (relative risk RR 0·27, 99·7% CI 0·07–0·99; p=0·0026). No difference in treatment failure was noted between patients in the bubble CPAP and those in the high-flow oxygen therapy group (RR 0·50, 99·7% 0·11–2·29; p=0·175). 23 (10%) children died. Three (4%) children died in the bubble CPAP group, ten (15%) children died in the low-flow oxygen therapy group, and ten (13%) children died in the high-flow oxygen therapy group. Children who received oxygen by bubble CPAP had significantly lower rates of death than the children who received oxygen by low-flow oxygen therapy (RR 0·25, 95% CI 0·07–0·89; p=0·022). Interpretation Oxygen therapy delivered by bubble CPAP improved outcomes in Bangladeshi children with very severe pneumonia and hypoxaemia compared with standard low-flow oxygen therapy. Use of bubble CPAP oxygen therapy could have a large effect in hospitals in developing countries where the only respiratory support for severe childhood pneumonia and hypoxaemia is low-flow oxygen therapy. The trial was stopped early because of higher mortality in the low-flow oxygen group than in the bubble CPAP group, and we acknowledge that the early cessation of the trial reduces the certainty of the findings. Further research is needed to test the feasibility of scaling up bubble CPAP in district hospitals and to improve bubble CPAP delivery technology. Funding International Centre for Diarrhoeal Disease Research, Bangladesh, and Centre for International Child Health, University of Melbourne.
Context.
55 Cnc e is a transiting super-Earth (radius 1.88
R
⊕
and mass 8
M
⊕
) orbiting a G8V host star on a 17-h orbit.
Spitzer
observations of the planet’s phase curve at 4.5 μm revealed a ...time-varying occultation depth, and MOST optical observations are consistent with a time-varying phase curve amplitude and phase offset of maximum light. Both broadband and high-resolution spectroscopic analyses are consistent with either a high mean molecular weight atmosphere or no atmosphere for planet e. A long-term photometric monitoring campaign on an independent optical telescope is needed to probe the variability in this system.
Aims.
We seek to measure the phase variations of 55 Cnc e with a broadband optical filter with the 30 cm effective aperture space telescope CHEOPS and explore how the precision photometry narrows down the range of possible scenarios.
Methods.
We observed 55 Cnc for 1.6 orbital phases in March of 2020. We designed a phase curve detrending toolkit for CHEOPS photometry which allowed us to study the underlying flux variations in the 55 Cnc system.
Results.
We detected a phase variation with a full-amplitude of 72 ± 7 ppm, but did not detect a significant secondary eclipse of the planet. The shape of the phase variation resembles that of a piecewise-Lambertian; however, the non-detection of the planetary secondary eclipse, and the large amplitude of the variations exclude reflection from the planetary surface as a possible origin of the observed phase variations. They are also likely incompatible with magnetospheric interactions between the star and planet, but may imply that circumplanetary or circumstellar material modulate the flux of the system.
Conclusions.
This year, further precision photometry of 55 Cnc from CHEOPS will measure variations in the phase curve amplitude and shape over time.
Observations of Faraday rotation for extragalactic sources probe magnetic fields both inside and outside the Milky Way. Building on our earlier estimate of the Galactic contribution, we set out to ...estimate the extragalactic contributions. We discuss the problems involved; in particular, we point out that taking the difference between the observed values and the Galactic foreground reconstruction is not a good estimate for the extragalactic contributions. We point out a degeneracy between the contributions to the observed values due to extragalactic magnetic fields and observational noise and comment on the dangers of over-interpreting an estimate without taking into account its uncertainty information. To overcome these difficulties, we develop an extended reconstruction algorithm based on the assumption that the observational uncertainties are accurately described for a subset of the data, which can overcome the degeneracy with the extragalactic contributions. We present a probabilistic derivation of the algorithm and demonstrate its performance using a simulation, yielding a high quality reconstruction of the Galactic Faraday rotation foreground, a precise estimate of the typical extragalactic contribution, and a well-defined probabilistic description of the extragalactic contribution for each data point. We then apply this reconstruction technique to a catalog of Faraday rotation observations for extragalactic sources. The analysis is done for several different scenarios, for which we consider the error bars of different subsets of the data to accurately describe the observational uncertainties. By comparing the results, we argue that a split that singles out only data near the Galactic poles is the most robust approach. We find that the dispersion of extragalactic contributions to observed Faraday depths is most likely lower than 7 rad/m2, in agreement with earlier results, and that the extragalactic contribution to an individual data point is poorly constrained by the data in most cases.
Objectives
There is a growing incidence of cognitive decline and dementia associated with the ageing population. Lifestyle factors such as diet, physical activity, and cognitive activities may ...individually or collectively be undertaken to increase one’s odds of preventing cognitive decline and future dementia. This study will examine whether clinical trials using multidomain lifestyle intervention can significantly decrease the risk of cognitive decline and therefore dementia.
Design, Setting and Participants
This systematic literature review of multidomain lifestyle interventions for the prevention of cognitive decline and dementia followed the PRISMA guidelines. Clinical trials involving multidomain intervention (i.e., diet and physical activity, or without cognitive training) in older adults (≥ 49 years old) at higher risk of dementia were identified through 5 electronic databases (EMBASE, MEDLINE, CINAHL, Cochrane, and Scopus). A comprehensive search was performed to identify and retrieve publications until 15 November 2022. Trials were published in English.
Results
The included studies (n=15) assessed change in cognition in response to a multidomain lifestyle intervention. However, the cognitive outcome measures used in these studies were heterogeneous. Despite this heterogeneity, two thirds of the studies showed improvement in cognition following a multidomain intervention (n=10 with a total of 9,439 participants). However, five studies reported no improvement in cognition following the multidomain intervention. The most common form of dietary intervention included higher amount of fruit and vegetable intake; whole-grain cereal products instead of refined; low fat options in milk and meat products; and limiting sucrose intake to less than 50 g/day. Most clinical trial studies were powered to examining the effects of multidomain interventions in cognition but were not designed to test the contribution of individual domains (i.e., dietary changes, increased physical activity, or increased cognitive stimulation alone).
Conclusion
This systematic review aimed to determine the effect of multimodal lifestyle interventions on cognitive outcomes in older adults at risk of dementia. We found that participants with conditions that may increase the risk of dementia, (e.g., hypertension, cardiovascular fragility) do benefit from multi-modal lifestyle changes including diet, physical activity, and cognitive training. Two thirds of studies using multidomain lifestyle interventions showed improvements in cognitive function. Trials with a focus on cognitive training, dietary improvement, and physical activity may prevent or delay cognitive decline in older adults including those at risk of developing dementia. Future studies should consider longer follow-up periods and adequate power to be able to examine the effects of each lifestyle component in the context of multimodal interventions.
The Ross Sea polynya is among the most productive regions in the Southern Ocean and may constitute a significant oceanic CO2 sink. Based on results from several field studies, this region has been ...considered seasonally iron limited, whereby a “winter reserve” of dissolved iron (dFe) is progressively depleted during the growing season to low concentrations (∼0.1 nM) that limit phytoplankton growth in the austral summer (December–February). Here we report new iron data for the Ross Sea polynya during austral summer 2005–2006 (27 December–22 January) and the following austral spring 2006 (16 November–3 December). The summer 2005–2006 data show generally low dFe concentrations in polynya surface waters (0.10 ± 0.05 nM in upper 40 m, n = 175), consistent with previous observations. Surprisingly, our spring 2006 data reveal similar low surface dFe concentrations in the polynya (0.06 ± 0.04 nM in upper 40 m, n = 69), in association with relatively high rates of primary production (∼170–260 mmol C m−2 d−1). These results indicate that the winter reserve dFe may be consumed relatively early in the growing season, such that polynya surface waters can become “iron limited” as early as November; i.e., the seasonal depletion of dFe is not necessarily gradual. Satellite observations reveal significant biomass accumulation in the polynya during summer 2006–2007, implying significant sources of “new” dFe to surface waters during this period. Possible sources of this new dFe include episodic vertical exchange, lateral advection, aerosol input, and reductive dissolution of particulate iron.
Key Points
Dissolved iron can be depleted to low levels (~0.1 nM) in the Ross Sea in spring
Despite dissolved iron depletion, algal production continues during summer
Sources of “new” dissolved iron are required to fuel summer production in the Ross Sea
Because information on age of onset, systemic involvement, and PV concurrence was available for 99.6%, 72.1%, and 86.7% of cases, we compared these features in patients bearing recessive IL36RN ...mutations (n = 49) and in those without pathogenic alleles at this locus (n = 166, see Table E1 and the Methods section in this article's Online Repository at www.jacionline.org).
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