Summary Background Surgery is increasingly used as treatment for refractory focal epilepsy; however, few rigorous reports of long-term outcome exist. We did this study to identify long-term outcome ...of epilepsy surgery in adults by establishing patterns of seizure remission and relapse after surgery. Methods We report long-term outcome of surgery for epilepsy in 615 adults (497 anterior temporal resections, 40 temporal lesionectomies, 40 extratemporal lesionectomies, 20 extratemporal resections, 11 hemispherectomies, and seven palliative procedures corpus callosotomy, subpial transection), with prospective annual follow-up for a median of 8 years (range 1–19). We used Kaplan-Meier survival analysis to estimate time to first seizure, and investigated patterns of seizure outcome. Findings We used survival methods to estimate that 52% (95% CI 48–56) of patients remained seizure free (apart from simple partial seizures SPS) at 5 years after surgery, and 47% (42–51) at 10 years. Patients who had extratemporal resections were more likely to have seizure recurrence than were those who had anterior temporal resections (hazard ratio HR 2·0, 1·1–3·6; p=0·02); whereas for those having lesionectomies, no difference from anterior lobe resection was recorded. Those with SPS in the first 2 years after temporal lobe surgery had a greater chance of subsequent seizures with impaired awareness than did those with no SPS (2·4, 1·5–3·9). Relapse was less likely the longer a person was seizure free and, conversely, remission was less likely the longer seizures continued. In 18 (19%) of 93 people, late remission was associated with introduction of a previously untried antiepileptic drug. 104 of 365 (28%) seizure-free individuals had discontinued drugs at latest follow-up. Interpretation Neurosurgical treatment is appealing for selected people with refractory focal epilepsy. Our data provide realistic expectations and indicate the scope for further improvements in presurgical assessment and surgical treatment of people with chronic epilepsy. Funding UK Department of Health National Institute for Health Research (NIHR) Biomedical Research Centres funding scheme, Epilepsy Society, Dr Marvin Weil Epilepsy Research Fund.
Detection of Silica-Rich Deposits on Mars Squyres, S.W; Arvidson, R.E; Ruff, S ...
Science (American Association for the Advancement of Science),
05/2008, Letnik:
320, Številka:
5879
Journal Article
Recenzirano
Mineral deposits on the martian surface can elucidate ancient environmental conditions on the planet. Opaline silica deposits (as much as 91 weight percent SiO₂) have been found in association with ...volcanic materials by the Mars rover Spirit. The deposits are present both as light-toned soils and as bedrock. We interpret these materials to have formed under hydrothermal conditions and therefore to be strong indicators of a former aqueous environment. This discovery is important for understanding the past habitability of Mars because hydrothermal environments on Earth support thriving microbial ecosystems.
Studies of inflammatory bowel disease (IBD) have been inconclusive in relating microbiota with distribution of inflammation. We report microbiota, host transcriptomics, epigenomics and genetics from ...matched inflamed and non-inflamed colonic mucosa 50 Crohn's disease (CD); 80 ulcerative colitis (UC); 31 controls. Changes in community-wide and within-patient microbiota are linked with inflammation, but we find no evidence for a distinct microbial diagnostic signature, probably due to heterogeneous host-microbe interactions, and show only marginal microbiota associations with habitual diet. Epithelial DNA methylation improves disease classification and is associated with both inflammation and microbiota composition. Microbiota sub-groups are driven by dominant Enterbacteriaceae and Bacteroides species, representative strains of which are pro-inflammatory in vitro, are also associated with immune-related epigenetic markers. In conclusion, inflamed and non-inflamed colonic segments in both CD and UC differ in microbiota composition and epigenetic profiles.
We use 23 atmospheric chemistry transport models to calculate current and future (2030) deposition of reactive nitrogen (NOy, NHx) and sulfate (SOx) to land and ocean surfaces. The models are driven ...by three emission scenarios: (1) current air quality legislation (CLE); (2) an optimistic case of the maximum emissions reductions currently technologically feasible (MFR); and (3) the contrasting pessimistic IPCC SRES A2 scenario. An extensive evaluation of the present‐day deposition using nearly all information on wet deposition available worldwide shows a good agreement with observations in Europe and North America, where 60–70% of the model‐calculated wet deposition rates agree to within ±50% with quality‐controlled measurements. Models systematically overestimate NHx deposition in South Asia, and underestimate NOy deposition in East Asia. We show that there are substantial differences among models for the removal mechanisms of NOy, NHx, and SOx, leading to ±1 σ variance in total deposition fluxes of about 30% in the anthropogenic emissions regions, and up to a factor of 2 outside. In all cases the mean model constructed from the ensemble calculations is among the best when comparing to measurements. Currently, 36–51% of all NOy, NHx, and SOx is deposited over the ocean, and 50–80% of the fraction of deposition on land falls on natural (nonagricultural) vegetation. Currently, 11% of the world's natural vegetation receives nitrogen deposition in excess of the “critical load” threshold of 1000 mg(N) m−2 yr−1. The regions most affected are the United States (20% of vegetation), western Europe (30%), eastern Europe (80%), South Asia (60%), East Asia (40%), southeast Asia (30%), and Japan (50%). Future deposition fluxes are mainly driven by changes in emissions, and less importantly by changes in atmospheric chemistry and climate. The global fraction of vegetation exposed to nitrogen loads in excess of 1000 mg(N) m−2 yr−1 increases globally to 17% for CLE and 25% for A2. In MFR, the reductions in NOy are offset by further increases for NHx deposition. The regions most affected by exceedingly high nitrogen loads for CLE and A2 are Europe and Asia, but also parts of Africa.
The martian surface is a natural laboratory for testing our understanding of the physics of aeolian (wind-related) processes in an environment different from that of Earth. Martian surface markings ...and atmospheric opacity are time-variable, indicating that fine particles at the surface are mobilized regularly by wind. Regolith (unconsolidated surface material) at the Mars Exploration Rover Opportunity's landing site has been affected greatly by wind, which has created and reoriented bedforms, sorted grains, and eroded bedrock. Aeolian features here preserve a unique record of changing wind direction and wind strength. Here we present an in situ examination of a martian bright wind streak, which provides evidence consistent with a previously proposed formational model for such features. We also show that a widely used criterion for distinguishing between aeolian saltation- and suspension-dominated grain behaviour is different on Mars, and that estimated wind friction speeds between 2 and 3 m s-1, most recently from the northwest, are associated with recent global dust storms, providing ground truth for climate model predictions.
Global tropospheric ozone distributions, budgets, and radiative forcings from an ensemble of 26 state‐of‐the‐art atmospheric chemistry models have been intercompared and synthesized as part of a ...wider study into both the air quality and climate roles of ozone. Results from three 2030 emissions scenarios, broadly representing “optimistic,” “likely,” and “pessimistic” options, are compared to a base year 2000 simulation. This base case realistically represents the current global distribution of tropospheric ozone. A further set of simulations considers the influence of climate change over the same time period by forcing the central emissions scenario with a surface warming of around 0.7K. The use of a large multimodel ensemble allows us to identify key areas of uncertainty and improves the robustness of the results. Ensemble mean changes in tropospheric ozone burden between 2000 and 2030 for the 3 scenarios range from a 5% decrease, through a 6% increase, to a 15% increase. The intermodel uncertainty (±1 standard deviation) associated with these values is about ±25%. Model outliers have no significant influence on the ensemble mean results. Combining ozone and methane changes, the three scenarios produce radiative forcings of −50, 180, and 300 mW m−2, compared to a CO2 forcing over the same time period of 800–1100 mW m−2. These values indicate the importance of air pollution emissions in short‐ to medium‐term climate forcing and the potential for stringent/lax control measures to improve/worsen future climate forcing. The model sensitivity of ozone to imposed climate change varies between models but modulates zonal mean mixing ratios by ±5 ppbv via a variety of feedback mechanisms, in particular those involving water vapor and stratosphere‐troposphere exchange. This level of climate change also reduces the methane lifetime by around 4%. The ensemble mean year 2000 tropospheric ozone budget indicates chemical production, chemical destruction, dry deposition and stratospheric input fluxes of 5100, 4650, 1000, and 550 Tg(O3) yr−1, respectively. These values are significantly different to the mean budget documented by the Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (TAR). The mean ozone burden (340 Tg(O3)) is 10% larger than the IPCC TAR estimate, while the mean ozone lifetime (22 days) is 10% shorter. Results from individual models show a correlation between ozone burden and lifetime, and each model's ozone burden and lifetime respond in similar ways across the emissions scenarios. The response to climate change is much less consistent. Models show more variability in the tropics compared to midlatitudes. Some of the most uncertain areas of the models include treatments of deep tropical convection, including lightning NOx production; isoprene emissions from vegetation and isoprene's degradation chemistry; stratosphere‐troposphere exchange; biomass burning; and water vapor concentrations.
The ripple field known as “El Dorado” was a unique stop on Spirit's traverse where dust‐raising, active mafic sand ripples and larger inactive coarse‐grained ripples interact, illuminating several ...long‐standing issues of Martian dust mobility, sand mobility, and the origin of transverse aeolian ridges. Strong regional wind events endured by Spirit caused perceptible migration of ripple crests in deposits SSE of El Dorado, erasure of tracks in sandy areas, and changes to dust mantling the site. Localized thermal vortices swept across El Dorado, leaving paths of reduced dust but without perceptibly damaging nearly cohesionless sandy ripple crests. From orbit, winds responsible for frequently raising clay‐sized dust into the atmosphere do not seem to significantly affect dunes composed of (more easily entrained) sand‐sized particles, a long‐standing paradox. This disparity between dust mobilization and sand mobilization on Mars is due largely to two factors: (1) dust occurs on the surface as fragile, low‐density, sand‐sized aggregates that are easily entrained and disrupted, compared with clay‐sized air fall particles; and (2) induration of regolith is pervasive. Light‐toned bed forms investigated at Gusev are coarse‐grained ripples, an interpretation we propose for many of the smallest linear, light‐toned bed forms of uncertain origin seen in high‐resolution orbital images across Mars. On Earth, wind can organize bimodal or poorly sorted loose sediment into coarse‐grained ripples. Coarse‐grained ripples could be relatively common on Mars because development of durable, well‐sorted sediments analogous to terrestrial aeolian quartz sand deposits is restricted by the lack of free quartz and limited hydraulic sediment processing.
Influenza A virus (IAV) infection leads to variable and imperfectly understood pathogenicity. We report that segment 3 of the virus contains a second open reading frame ("X-ORF"), accessed via ...ribosomal frameshifting. The frameshift product, termed PA-X, comprises the endonuclease domain of the viral PA protein with a C-terminal domain encoded by the X-ORF and functions to repress cellular gene expression. PA-X also modulates IAV virulence in a mouse infection model, acting to decrease pathogenicity. Loss of PA-X expression leads to changes in the kinetics of the global host response, which notably includes increases in inflammatory, apoptotic, and T lymphocyte-signaling pathways. Thus, we have identified a previously unknown IAV protein that modulates the host response to infection, a finding with important implications for understanding IAV pathogenesis.
Erosion rates derived from the Gusev cratered plains and the erosion of weak sulfates by saltating sand at Meridiani Planum are so slow that they argue that the present dry and desiccating ...environment has persisted since the Early Hesperian. In contrast, sedimentary rocks at Meridiani formed in the presence of groundwater and occasional surface water, and many Columbia Hills rocks at Gusev underwent aqueous alteration during the Late Noachian, approximately coeval with a wide variety of geomorphic indicators that indicate a wetter and likely warmer environment. Two-toned rocks, elevated ventifacts, and perched and undercut rocks indicate localized deflation of the Gusev plains and deposition of an equivalent amount of sediment into craters to form hollows, suggesting average erosion rates of approx.0.03 nm/yr. Erosion of Hesperian craters, modification of Late Amazonian craters, and the concentration of hematite concretions in the soils of Meridiani yield slightly higher average erosion rates of 1-10 nm/yr in the Amazonian. These erosion rates are 2-5 orders of magnitude lower than the slowest continental denudation rates on Earth, indicating that liquid water was not an active erosional agent. Erosion rates for Meridiani just before deposition of the sulfate-rich sediments and other eroded Noachian areas are comparable with slow denudation rates on Earth that are dominated by liquid water. Available data suggest the climate change at the landing sites from wet and likely warm to dry and desiccating occurred sometime between the Late Noachian and the beginning of the Late Hesperian (3.7-3.5 Ga).
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