New and previously unimaginable Landsat applications have been fostered by a policy change in 2008 that made analysis-ready Landsat data free and open access. Since 1972, Landsat has been collecting ...images of the Earth, with the early years of the program constrained by onboard satellite and ground systems, as well as limitations across the range of required computing, networking, and storage capabilities. Rather than robust on-satellite storage for transmission via high bandwidth downlink to a centralized storage and distribution facility as with Landsat-8, a network of receiving stations, one operated by the U.S. government, the other operated by a community of International Cooperators (ICs), were utilized. ICs paid a fee for the right to receive and distribute Landsat data and over time, more Landsat data was held outside the archive of the United State Geological Survey (USGS) than was held inside, much of it unique. Recognizing the critical value of these data, the USGS began a Landsat Global Archive Consolidation (LGAC) initiative in 2010 to bring these data into a single, universally accessible, centralized global archive, housed at the Earth Resources Observation and Science (EROS) Center in Sioux Falls, South Dakota. The primary LGAC goals are to inventory the data held by ICs, acquire the data, and ingest and apply standard ground station processing to generate an L1T analysis-ready product. As of January 1, 2015 there were 5,532,454 images in the USGS archive. LGAC has contributed approximately 3.2 million of those images, more than doubling the original USGS archive holdings. Moreover, an additional 2.3 million images have been identified to date through the LGAC initiative and are in the process of being added to the archive. The impact of LGAC is significant and, in terms of images in the collection, analogous to that of having had two additional Landsat-5 missions. As a result of LGAC, there are regions of the globe that now have markedly improved Landsat data coverage, resulting in an enhanced capacity for mapping, monitoring change, and capturing historic conditions. Although future missions can be planned and implemented, the past cannot be revisited, underscoring the value and enhanced significance of historical Landsat data and the LGAC initiative. The aim of this paper is to report the current status of the global USGS Landsat archive, document the existing and anticipated contributions of LGAC to the archive, and characterize the current acquisitions of Landsat-7 and Landsat-8. Landsat-8 is adding data to the archive at an unprecedented rate as nearly all terrestrial images are now collected. We also offer key lessons learned so far from the LGAC initiative, plus insights regarding other critical elements of the Landsat program looking forward, such as acquisition, continuity, temporal revisit, and the importance of continuing to operationalize the Landsat program.
•USGS Landsat archive contained 5.5 million images as of January 1, 2015.•To date 3.2 million images were added by the Landsat Global Archive Consolidation (LGAC).•LGAC will consolidate an additional of ~2.3 million images into the UGSG archive.•As of January 1, 2015, LGAC had contributed 57% of the images in the USGS archive.•Ground systems are an important element of operational land imaging activities.
In acute ischemic stroke, thrombectomy with a stent retriever plus intravenous t-PA was more effective than t-PA in improving functional outcomes. At 90 days, 60% of patients in the intervention ...group were functionally independent, as compared with 35% in the control group.
Intravenous tissue plasminogen activator (t-PA) administered within 4.5 hours after the onset of acute ischemic stroke improves outcomes.
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However, intravenous t-PA has multiple constraints, including unresponsiveness of large thrombi to rapid enzymatic digestion, a narrow time window for administration, and the risk of cerebral and systemic hemorrhage. Among patients with occlusions of the intracranial internal carotid artery or the first segment of the middle cerebral artery (or both), intravenous t-PA results in early reperfusion in only 13 to 50%.
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Neurovascular thrombectomy is a reperfusion strategy that is distinct from pharmacologic fibrinolysis. Endovascular mechanical treatments can remove large, proximal . . .
The current International Association for the Study of Pain (IASP) definition of pain as "An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or ...described in terms of such damage" was recommended by the Subcommittee on Taxonomy and adopted by the IASP Council in 1979. This definition has become accepted widely by health care professionals and researchers in the pain field and adopted by several professional, governmental, and nongovernmental organizations, including the World Health Organization. In recent years, some in the field have reasoned that advances in our understanding of pain warrant a reevaluation of the definition and have proposed modifications. Therefore, in 2018, the IASP formed a 14-member, multinational Presidential Task Force comprising individuals with broad expertise in clinical and basic science related to pain, to evaluate the current definition and accompanying note and recommend whether they should be retained or changed. This review provides a synopsis of the critical concepts, the analysis of comments from the IASP membership and public, and the committee's final recommendations for revisions to the definition and notes, which were discussed over a 2-year period. The task force ultimately recommended that the definition of pain be revised to "An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage," and that the accompanying notes be updated to a bulleted list that included the etymology. The revised definition and notes were unanimously accepted by the IASP Council early this year.
Hot Topics in Tetralogy of Fallot Villafañe, Juan, MD; Feinstein, Jeffrey A., MD; Jenkins, Kathy J., MD, MPH ...
Journal of the American College of Cardiology,
12/2013, Letnik:
62, Številka:
23
Journal Article
Recenzirano
Odprti dostop
Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart defect. We explore “hot topics” to highlight areas of emerging science for clinicians and scientists in moving toward a better ...understanding of the long-term management of patients with repaired TOF. From a genetic perspective, the etiology of TOF is multifactorial, with a familial recurrence risk of 3%. Cardiac magnetic resonance is the gold standard assessment tool based on its superior imaging of the right ventricular (RV) outflow tract, pulmonary arteries, aorta, and aortopulmonary collaterals, and on its ability to quantify biventricular size and function, pulmonary regurgitation (PR), and myocardial viability. Atrial re-entrant tachycardia will develop in more than 30% of patients, and high-grade ventricular arrhythmias will be seen in about 10% of patients. The overall incidence of sudden cardiac death is estimated at 0.2%/yr. Risk stratification, even with electrophysiologic testing and cardiac magnetic resonance, remains imperfect. Drug therapy has largely been abandoned, and defibrillator placement, despite its high risks for complications and inappropriate discharges, is often recommended for patients at higher risk. Definitive information about optimal surgical strategies for primary repair to preserve RV function, reduce arrhythmia, and optimize functional status is lacking. Post-operative lesions are often amenable to transcatheter intervention. In selected cases, PR may be treated with transcatheter valve insertion. Ongoing surveillance of RV function is a crucial component of clinical assessment. Except for resynchronization with biventricular pacing, no medical therapies have been shown to be effective after RV dysfunction occurs. In patients with significant PR with RV dilation, optimal timing of pulmonary valve replacement remains uncertain, although accepted criteria are emerging.
In this review, we examine the potential and the challenges of designing an ultrathin reverse osmosis (RO) membrane from graphene, focusing on the role of computational methods in designing, ...understanding, and optimizing the relationship between atomic structure and RO performance. In recent years, graphene has emerged as a promising material for improving the performance of RO. Beginning at the atomic scale and extending to the RO plant scale, we review applications of computational research that have explored the structure, properties and potential performance of nanoporous graphene in the context of RO desalination.
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•We review recent progress in the computational study of graphene as an RO membrane.•We introduce graphene and current knowledge about its mass transport properties.•We examine six key mechanisms that govern salt rejection in graphene.•Molecular dynamics have played a dominant role in the study of graphene membranes.•We suggest a greater role for quantum-level simulations and macroscale computation.
In this randomized comparison of stenting and endarterectomy as treatment for carotid-artery stenosis, there was no significant difference in the rate of the composite primary end point of stroke, ...myocardial infarction, or death (7.2% and 6.8%, respectively; P=0.51). Stroke was more common with carotid-artery stenting than carotid endarterectomy; myocardial infarction was more common with carotid endarterectomy. The 4-year rate of stroke or death was 6.4% for carotid-artery stenting and 4.7% for carotid endarterectomy (P=0.03).
In this randomized comparison of stenting and endarterectomy as treatment for carotid-artery stenosis, there was no significant difference in the rate of the composite primary end point of stroke, myocardial infarction, or death (7.2% and 6.8%, respectively).
Carotid-artery atherosclerosis is an important cause of ischemic stroke.
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Carotid endarterectomy has been established as effective treatment for both symptomatic patients and asymptomatic patients.
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Carotid-artery stenting is another option for treatment. The results of randomized trials comparing carotid-artery stenting and carotid endarterectomy for use in symptomatic patients are conflicting.
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The primary aim of the Carotid Revascularization Endarterectomy vs. Stenting Trial (CREST) was to compare the outcomes of carotid-artery stenting with those of carotid endarterectomy among patients with symptomatic or asymptomatic extracranial carotid stenosis.
Methods
Study Design
CREST is a randomized, controlled trial with blinded end-point adjudication. Ethics review . . .
Human exposure to per- and polyfluoroalkyl substances (PFAS) has been primarily attributed to contaminated food and drinking water. There is information indicating other sources and pathways of ...exposure in residential environments, but few studies report relationships between these indoor media and human biomonitoring measurements.
This study adapts existing systematic review tools and methodologies to synthesize evidence for PFAS exposure pathways from indoor environment media including consumer products, household articles, cleaning products, personal care products, and indoor air and dust. Studies were identified using innovative machine learning approaches and pathway-specific search strings to reduce time needed for literature search and screening. The included studies and systematic review were evaluated using tools modified specifically for exposure studies. The systematic review was conducted following a previously published protocol (DeLuca et al., 2021) that describes the systematic review methodology used in detail.
Only 7 studies were identified that measured the targeted subset of 8 PFAS chemicals in concordant household media (primarily house dust) and participant serum. Data extracted from the included studies were used to calculate exposure intake rates and estimate a percentage of occupant serum concentrations that could be attributed to the indoor exposure pathways. These calculations showed that exposure to PFOA, PFOS, PFNA, and PFHxS from contaminated house dust could account for 13%, 3%, 7%, and 25% of serum concentrations, respectively. Inhalation of PFAS in indoor air could account for less than 4% of serum PFOA concentrations and less than 2% of serum PFOS and PFNA concentrations. A risk of bias was identified due to participant profiles in most of the studies being skewed towards white, female, and higher socioeconomic status.
Along with synthesizing evidence for estimated contributions to serum PFAS levels from indoor exposure media, this systematic review also identifies a consistent risk of bias across exposure study populations that should be considered in future studies. It highlights a major research gap and need for studies that measure concordant data from both indoor exposure media and participant serum and the need for continued research on exposure modeling parameters for many PFAS chemicals.
This study investigated the effectiveness of implementing a plasma discharge to improve combustor dynamics and flame stability. Specifically, a nano-second pulsed plasma discharge (NSPD) was applied ...to a premixed gaseous fuel/air dump combustor for mitigation of dynamic combustion instabilities with a minimal NO
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penalty. As a result, a significant reduction of pressure fluctuation level (2X to 4X) was observed at realistic low-power conditions of aero-engine combustors. The plasma power required for the reduction increased with increasing combustor inlet velocity and pressure. The change of fuel from methane to propane required significantly (2X) higher plasma power to achieve a similar noise reduction. The lean blowout limit was significantly extended due to the plasma; however, substantial incomplete combustion occurred in the extended regime. The incremental NO
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production in the presence of the plasma was low (~ < 1EINO
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); however, it increased with decreasing velocity and pressure, and increasing temperature.
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