254 research outputs found

    Accounting for end-user preferences in earthquake early warning systems

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    Earthquake early warning systems (EEWSs) that rapidly trigger risk-reduction actions after a potentially-damaging earthquake is detected are an attractive tool to reduce seismic losses. One brake on their implementation in practice is the difficulty in setting the threshold required to trigger pre-defined actions: set the level too high and the action is not triggered before potentially-damaging shaking occurs and set the level too low and the action is triggered too readily. Balancing these conflicting requirements of an EEWS requires a consideration of the preferences of its potential end users. In this article a framework to define these preferences, as part of a participatory decision making procedure, is presented. An aspect of this framework is illustrated for a hypothetical toll bridge in a seismically-active region, where the bridge owners wish to balance the risk to people crossing the bridge with the loss of toll revenue and additional travel costs in case of bridge closure. Multi-attribute utility theory (MAUT) is used to constrain the trigger threshold for four owners with different preferences. We find that MAUT is an appealing and transparent way of aiding the potentially controversial decision of what level of risk to accept in EEW

    Lithologic Controls on Silicate Weathering Regimes of Temperate Planets

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    Weathering of silicate rocks at a planetary surface can draw down CO2 from the atmosphere for eventual burial and long-term storage in the planetary interior. This process is thought to provide essential negative feedback to the carbonate-silicate cycle (carbon cycle) to maintain clement climates on Earth and potentially similar temperate exoplanets. We implement thermodynamics to determine weathering rates as a function of surface lithology (rock type). These rates provide upper limits that allow the maximum rate of weathering in regulating climate to be estimated. This modeling shows that the weathering of mineral assemblages in a given rock, rather than individual minerals, is crucial to determine weathering rates at planetary surfaces. By implementing a fluid-transport-controlled approach, we further mimic chemical kinetics and thermodynamics to determine weathering rates for three types of rocks inspired by the lithologies of EarthÊŒs continental and oceanic crust, and its upper mantle. We find that thermodynamic weathering rates of a continental crust-like lithology are about one to two orders of magnitude lower than those of a lithology characteristic of the oceanic crust. We show that when the CO2 partial pressure decreases or surface temperature increases, thermodynamics rather than kinetics exerts a strong control on weathering. The kinetically and thermodynamically limited regimes of weathering depend on lithology, whereas the supply-limited weathering is independent of lithology. Our results imply that the temperature sensitivity of thermodynamically limited silicate weathering may instigate a positive feedback to the carbon cycle, in which the weathering rate decreases as the surface temperature increases

    Nanodisc-cell fusion: Control of fusion pore nucleation and lifetimes by SNARE protein transmembrane domains

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    The initial, nanometer-sized connection between the plasma membrane and a hormone- or neurotransmitter-filled vesicle-the fusion pore- can flicker open and closed repeatedly before dilating or resealing irreversibly. Pore dynamics determine release and vesicle recycling kinetics, but pore properties are poorly known because biochemically defined single-pore assays are lacking. We isolated single flickering pores connecting v-SNARE-reconstituted nanodiscs to cells ectopically expressing cognate, "flipped" t-SNAREs. Conductance through single, voltage-clamped fusion pores directly reported sub-millisecond pore dynamics. Pore currents fluctuated, transiently returned to baseline multiple times, and disappeared ∌6 s after initial opening, as if the fusion pore fluctuated in size, flickered, and resealed. We found that interactions between v- and t-SNARE transmembrane domains (TMDs) promote, but are not essential for pore nucleation. Surprisingly, TMD modifications designed to disrupt v- and t-SNARE TMD zippering prolonged pore lifetimes dramatically. We propose that the post-fusion geometry of the proteins contribute to pore stability.Fil: Wu, Zhenyong. University of Yale; Estados Unidos. University of Yale. School of Medicine; Estados UnidosFil: Auclair, Sarah M.. University of Yale. School of Medicine; Estados Unidos. University of Yale; Estados UnidosFil: Bello, Oscar Daniel. University of Yale. School of Medicine; Estados Unidos. University of Yale; Estados Unidos. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Mendoza. Instituto de HistologĂ­a y EmbriologĂ­a de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias MĂ©dicas. Instituto de HistologĂ­a y EmbriologĂ­a de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Vennekate, Wensi. University of Yale. School of Medicine; Estados Unidos. University of Yale; Estados UnidosFil: Dudzinski, Natasha R.. University of Yale; Estados Unidos. University of Yale. School of Medicine; Estados UnidosFil: Krishnakumar, Shyam S.. University of Yale. School of Medicine; Estados Unidos. University of Yale; Estados UnidosFil: Karatekin, Erdem. University of Yale; Estados Unidos. University of Yale. School of Medicine; Estados Unidos. Universite Paris Descartes; Francia. Centre National de la Recherche Scientifique; Franci

    Dilation of fusion pores by crowding of SNARE proteins

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    Hormones and neurotransmitters are released through fluctuating exocytotic fusion pores that can flicker open and shut multiple times. Cargo release and vesicle recycling depend on the fate of the pore, which may reseal or dilate irreversibly. Pore nucleation requires zippering between vesicle-associated v-SNAREs and target membrane t-SNAREs, but the mechanisms governing the subsequent pore dilation are not understood. Here, we probed the dilation of single fusion pores using v-SNARE-reconstituted ~23-nm-diameter discoidal nanolipoprotein particles (vNLPs) as fusion partners with cells ectopically expressing cognate, ’flipped’ t-SNAREs. Pore nucleation required a minimum of two v-SNAREs per NLP face, and further increases in v-SNARE copy numbers did not affect nucleation rate. By contrast, the probability of pore dilation increased with increasing v-SNARE copies and was far from saturating at 15 v-SNARE copies per face, the NLP capacity. Our experimental and computational results suggest that SNARE availability may be pivotal in determining whether neurotransmitters or hormones are released through a transient (’kiss and run’) or an irreversibly dilating pore (full fusion).Fil: Wu, Zhenyong. University of Yale; Estados Unidos. University of Yale. School of Medicine; Estados UnidosFil: Bello, Oscar Daniel. University of Yale. School of Medicine; Estados Unidos. University of Yale; Estados Unidos. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Mendoza. Instituto de HistologĂ­a y EmbriologĂ­a de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias MĂ©dicas. Instituto de HistologĂ­a y EmbriologĂ­a de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Thiyagarajan, Sathish. Columbia University; Estados UnidosFil: Auclair, Sarah Marie. University of Yale. School of Medicine; Estados Unidos. University of Yale; Estados UnidosFil: Vennekate, Wensi. University of Yale; Estados Unidos. University of Yale. School of Medicine; Estados UnidosFil: Krishnakumar, Shyam S. University of Yale; Estados Unidos. University of Yale. School of Medicine; Estados UnidosFil: O'Shaughnessy, Ben. Columbia University; Estados UnidosFil: Karatekin, Erdem. University of Yale; Estados Unidos. Universite Paris Descartes; Francia. University of Yale. School of Medicine; Estados Unido

    The physiological burden of the 6-minute walk test compared with cardiopulmonary exercise stress test in patients with severe aortic atenosis

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    Background Management of aortic stenosis (AS) relies on symptoms. Exercise testing is recommended for asymptomatic patients with significant AS but is often experienced as forbidding and/or technically unrealistic for patients who are often frail, deconditioned, and intimidated by the exercise test. We compared the physiological burden assessed with gas exchange assessments to gauge and respiratory exchange ratio (RER) of a 6-minute walk test (6MWT) to a cardiopulmonary exercise stress test (CPET) in patients with severe AS. peak oxygen utilization Methods Adults with equivocal symptoms and severe AS (1-aortic valve area [AVA] ≀ 1.0 cm2 or AVA index ≀ 0.6 cm2/m2, 2-peak aortic jet velocity ≄ 4.0 m/sec, 3-mean transvalvular pressure gradient ≄ 40 mm Hg by rest or dobutamine stress echocardiography, or 4-aortic valve calcification ≄ 1200 in women or ≄ 2000 AU in men) were studied. All participants completed both a 6MWT and symptom-limited progressive bicycle exercise testing. Breath-by-breath gas analysis and 12-lead electrocardiography were completed during 6MWT and CPET. Results: Eleven patients were studied. Patients walked on average 330 ± 75 m during the 6MWT and achieved a maximal workload of 48 ± 14 watts during the CPET. During the 6MWT, peak maximal oxygen uptake (O2peak) was 12.8 ± 2.5 vs 10.8 ± 4.2 mL/kg/min during the CPET. Respiratory exchange ratio exceeded 1.1 in both the 6MWT and CPET indicating similarly high exertion. Compared with the CPET, a larger proportion of the 6MWT was performed at a high intensity level (78% ± 28% vs 33% ± 24% at > 85% V̇O2peak; P = 0.004). Conclusions The 6MWT with breath-by-breath gas analysis was well tolerated and able to achieve a physiological intense RER and O2peak that are similar to symptom-limited CPET in patients with severe AS.Introduction La prise en charge de la stĂ©nose aortique (SA) dĂ©pend des symptĂŽmes. L’épreuve d’effort est recommandĂ©e aux patients asymptomatiques qui ont une SA significative, mais elle est souvent perçue comme dangereuse et/ou thĂ©oriquement irrĂ©aliste chez ces patients qui sont souvent fragiles, en mauvaise forme et craintifs par l’épreuve d’effort. Nous avons comparĂ© le fardeau physiologique calculĂ© par la consommation maximale de l’oxygĂšne (O2max) et le quotient respiratoire (QR) d’un test de marche de 6 minutes (TM6) et d'une Ă©preuve d’effort maximal chez des patients avec une SA sĂ©vĂšre. MĂ©thodes Tous les patients prĂ©sentaient une SA symptomatique et sĂ©vĂšre (1-aire valvulaire aortique [AVA] ≀ 1,0 cm2 ouAVA ≀ 0,6 cm2/m2, 2-une vĂ©locitĂ© maximale du flux aortique ≄ 4,0 m/sec, 3-un gradient de pression transvalvulaire moyen ≄ 40 mmHg au repos ou Ă  l’échocardiographie Ă  l’effort sous dobutamine ou 4-une calcification valvulaire aortique (AU) ≄ 1200 chez les femmes ou ≄ 2000 AU chez les hommes). Les participants ont effectuĂ© un TM6 et une ’épreuve d’effort maximal de type rampe sur vĂ©lo. L’analyse des Ă©changes gazeux respiration par respiration et un Ă©lectrocardiogramme Ă  12 dĂ©rivations ont Ă©tĂ© effectuĂ©s durant le TM6 et l'Ă©preuve d'effort maximal. RĂ©sultats Un total de 11 patients ont participĂ© Ă  l'Ă©tude. Les patients ont marchĂ© en moyenne 330 ± 75 m durant le TM6 et ont atteint une charge de travail maximale de 48 ± 14 watts durant l’épreuve d'effort maximal. Durant le TM6, le O2max Ă©tait de 12,8 ± 2,5 vs 10,8 ± 4,2 ml/kg/min durant l’épreuve d'effort maximal. Le QR Ă©tait supĂ©rieur Ă  1,1 au TM6 ainsi qu'Ă  l’épreuve d'effort maximal. Comparativement Ă  l’épreuve d'effort maximal, un pourcentage plus important au TM6 a Ă©tĂ© rĂ©alisĂ©e Ă  une intensitĂ© Ă©levĂ©e (78 % ± 28 % vs 33 % ± 24 % Ă  > 85 % V̇O2max; P = 0,004). Conclusions Le TM6 avec mesure directe des Ă©changes gazeux Ă©tait bien tolĂ©rĂ© et susceptible d’atteindre des valeurs physiologiques d'intensitĂ© Ă©levĂ©e pour le QR et le O2max. Les valeurs atteintes au TM6 Ă©taient semblables Ă  celles de l'Ă©preuve d'effort maximal chez les patients avec une SA sĂ©vĂšre

    Insights into high-risk multiple myeloma from an analysis of the role of PHF19 in cancer

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    Despite improvements in outcome, 15-25% of newly diagnosed multiple myeloma (MM) patients have treatment resistant high-risk (HR) disease with a poor survival. The lack of a genetic basis for HR has focused attention on the role played by epigenetic changes. Aberrant expression and somatic mutations affecting genes involved in the regulation of tri-methylation of the lysine (K) 27 on histone 3 H3 (H3K27me3) are common in cancer. H3K27me3 is catalyzed by EZH2, the catalytic subunit of the Polycomb Repressive Complex 2 (PRC2). The deregulation of H3K27me3 has been shown to be involved in oncogenic transformation and tumor progression in a variety of hematological malignancies including MM. Recently we have shown that aberrant overexpression of the PRC2 subunit PHD Finger Protein 19 (PHF19) is the most significant overall contributor to HR status further focusing attention on the role played by epigenetic change in MM. By modulating both the PRC2/EZH2 catalytic activity and recruitment, PHF19 regulates the expression of key genes involved in cell growth and differentiation. Here we review the expression, regulation and function of PHF19 both in normal and the pathological contexts of solid cancers and MM. We present evidence that strongly implicates PHF19 in the regulation of genes important in cell cycle and the genetic stability of MM cells making it highly relevant to HR MM behavior. A detailed understanding of the normal and pathological functions of PHF19 will allow us to design therapeutic strategies able to target aggressive subsets of MM

    Establishment and Spread of a Single Parthenogenic Genotype of the Mediterranean arundo wasp, Tetramesa romana1, In the Variable Climate of Texas

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    As part of a biological control program for the invasive weed, Arundo donax L., several genotypically unique populations of the parthenogenetic stemgalling wasp, Tetramesa romana Walker (Hymenoptera: Eurytomidae), from Spain and France were released in an infested riparian zone along the Rio Grande from Brownsville to Del Rio, TX. An adventive population of the wasp of unknown origin with limited distribution in Texas was also discovered, evaluated, and released as part of the program. More than 1.2 million wasps representing the mixture of genotypes were aerially released from 2009 to 2011. Wasps dispersed from their original release locations and now have a continuous distribution along the Rio Grande from Brownsville to Del Rio, and have dispersed throughout most of Central Texas with satellite populations as far west as San Angelo (Tom Green County), north as far as Kaufman (Kaufman County), and east to Navasota (Grimes County). The most successful genotype (#4) represented 390 of the 409 wasps recovered and matched both an imported population from the Mediterranean coast of Spain and an adventive population established in Texas before the start of the biological control program. Several other European genotypes of the wasp released in the program apparently failed to establish. This result demonstrated the benefits of evaluating and releasing the maximum genetic diversity of the biological control agent in the introduced range. Abundance of T. romana on the Rio Grande from Laredo to Del Rio averaged 190% more in 2013-2014 compared to a similar study in 2008-2009 before release of the European wasps. A favorability index was developed that showed that conditions from 1969 to 1977 would have been adverse to the wasp; conditions after 2009 were more favorable. Climate matching predicts the wasp will disperse throughout the southern U.S. and Mexico
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