76 research outputs found

    Design and Construction of a Molecular Beamline for Cluster Catalysis Studies

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    Metal and metal oxide nanoparticles are widely used in heterogeneous catalysis. In order to determine how these catalysts function and in order to find new catalysts, model systems can be used to provide experimental and computational insight. One such model system is a cluster which contains <100 atoms allowing for ease of calculation. In this work a molecular beamline was constructed in order to produce a wide range of these clusters and control their composition on an atom-by-atom level. These clusters could then be deposited onto a substrate in vacuum and studied via multiple techniques including TPD, XPS, UPS, LEED, and STM, allowing for the study of not only the cluster’s composition but their reactivity to a range of reactants in a range of reaction environments. In the process of designing the instrument, novel tools and parts were developed and manufactured to push the capabilities of the instrument forward and are discussed in detail. The instrument was tested and found to meet the three design goals of a molecular beamline that can 1) produce a large range of clusters varying in size and composition of a magnitude that can be deposited and studied in a timely fashion, 2) mass select the clusters with a resolution capable of resolving the elements in the cluster, and 3) bring to bear a variety of analytical techniques to study the cluster’s composition and catalytic capabilities

    The Limpopo Low-Level Jet: mean climatology and role in water vapor transport

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    Low-level jets (LLJs) are well established as critical features of regional climates globally. However, across sub-Saharan Africa, LLJs have received relatively little attention, in part due to a lack of data. Utilizing high-resolution reanalysis data, this paper develops the first climatology of a neglected feature of the southern African circulation – the Limpopo LLJ – and investigates its role in delivering water vapor to the continental interior. We demonstrate that the LLJ has a clear diurnal cycle and is a regular feature of the circulation throughout the year, forming on 80.9% of days. The pressure gradient between southern Mozambique and the continental interior acts as a first-order control on the annual cycle of jet strength, which peaks in October, achieving average maximum windspeeds of 15.8 m.s−1 at the core. Water vapor transport follows the same clear diurnal cycle, with at least 72% occurring over 18:00–08:00, and is closely related to jet strength: On average the strongest jet events advect 1.04 × 1012 kg (1.02 × 1012 kg) more moisture each night than the weakest in October-December (January-March). Strong jet events are typically linked to ridging anticyclones along the east coast of South Africa and are associated with increased rainfall in central and southern Botswana and northern South Africa the following day

    Attitudes towards gender roles and prevalence of intimate partner violence perpetrated against pregnant and postnatal women: Differences between women immigrants from conflict-affected countries and women born in Australia

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    BACKGROUND: The aim was to compare, for the first time in a large systematic study, women born in conflict-affected countries who immigrated to Australia with women born in Australia for attitudes towards gender roles and men\u27s use of IPV and the actual prevalence of IPV. The study also examined if any associations remained across the two timepoints of pregnancy and postpartum. METHODS: Women were interviewed during their first visit to one of three Australian public hospital antenatal clinics and re-interviewed at home six months after giving birth. A total of 1111 women completed both interviews, 583 were born in conflict-affected countries and 528 born in Australia. Associations between attitudes towards gender roles and men\u27s use of IPV, socio-demographic characteristics and reported actual experiences of IPV were examined using bivariate and multiple logistic regression analyses. RESULTS: Attitudes toward inequitable gender roles including those that condone men\u27s use of IPV, and prevalence of IPV, were significantly higher (p \u3c 0.001) among women born in conflict-affected countries compared to Australia-born women. Women born in conflict-affected countries with the strongest held attitudes towards gender roles and men\u27s use of IPV had an adjusted odds ratio (aOR) of 3.18 for IPV at baseline (95% CI 1.85-5.47) and an aOR of 1.83 for IPV at follow-up (95% CI 1.11-3.01). Women born in Australia with the strongest held attitudes towards gender roles and IPV had an aOR of 7.12 for IPV at baseline (95% CI 2.12-23.92) and an aOR of 10.59 for IPV at follow-up (95% CI 2.21-50.75). CONCLUSIONS: Our results underscore the need for IPV prevention strategies sensitively targeted to communities from conflict-affected countries, and for awareness among clinicians of gender role attitudes that may condone men\u27s use of IPV, and the associated risk of IPV. The study supports the need for culturally informed national strategies to promote gender equality and to challenge practices and attitudes that condone men\u27s violence in spousal relationships

    Lucy's Flat Feet: The Relationship between the Ankle and Rearfoot Arching in Early Hominins

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    BACKGROUND. In the Plio-Pleistocene, the hominin foot evolved from a grasping appendage to a stiff, propulsive lever. Central to this transition was the development of the longitudinal arch, a structure that helps store elastic energy and stiffen the foot during bipedal locomotion. Direct evidence for arch evolution, however, has been somewhat elusive given the failure of soft-tissue to fossilize. Paleoanthropologists have relied on footprints and bony correlates of arch development, though little consensus has emerged as to when the arch evolved. METHODOLOGY/PRINCIPAL FINDINGS. Here, we present evidence from radiographs of modern humans (n=261) that the set of the distal tibia in the sagittal plane, henceforth referred to as the tibial arch angle, is related to rearfoot arching. Non-human primates have a posteriorly directed tibial arch angle, while most humans have an anteriorly directed tibial arch angle. Those humans with a posteriorly directed tibial arch angle (8%) have significantly lower talocalcaneal and talar declination angles, both measures of an asymptomatic flatfoot. Application of these results to the hominin fossil record reveals that a well developed rearfoot arch had evolved in Australopithecus afarensis. However, as in humans today, Australopithecus populations exhibited individual variation in foot morphology and arch development, and "Lucy" (A.L. 288-1), a 3.18 Myr-old female Australopithecus, likely possessed asymptomatic flat feet. Additional distal tibiae from the Plio-Pleistocene show variation in tibial arch angles, including two early Homo tibiae that also have slightly posteriorly directed tibial arch angles. CONCLUSIONS/SIGNIFICANCE. This study finds that the rearfoot arch was present in the genus Australopithecus. However, the female Australopithecus afarensis "Lucy" has an ankle morphology consistent with non-pathological flat-footedness. This study suggests that, as in humans today, there was variation in arch development in Plio-Pleistocene hominins.Leakey Foundatio

    Association of Endovascular Thrombectomy vs Medical Management With Functional and Safety Outcomes in Patients Treated Beyond 24 Hours of Last Known Well: The SELECT Late Study

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    IMPORTANCE: The role of endovascular thrombectomy is uncertain for patients presenting beyond 24 hours of the time they were last known well. OBJECTIVE: To evaluate functional and safety outcomes for endovascular thrombectomy (EVT) vs medical management in patients with large-vessel occlusion beyond 24 hours of last known well. DESIGN, SETTING, AND PARTICIPANTS: This retrospective observational cohort study enrolled patients between July 2012 and December 2021 at 17 centers across the United States, Spain, Australia, and New Zealand. Eligible patients had occlusions in the internal carotid artery or middle cerebral artery (M1 or M2 segment) and were treated with EVT or medical management beyond 24 hours of last known well. INTERVENTIONS: Endovascular thrombectomy or medical management (control). MAIN OUTCOMES AND MEASURES: Primary outcome was functional independence (modified Rankin Scale score 0-2). Mortality and symptomatic intracranial hemorrhage (sICH) were safety outcomes. Propensity score (PS)-weighted multivariable logistic regression analyses were adjusted for prespecified clinical characteristics, perfusion parameters, and/or Alberta Stroke Program Early CT Score (ASPECTS) and were repeated in subsequent 1:1 PS-matched cohorts. RESULTS: Of 301 patients (median [IQR] age, 69 years [59-81]; 149 female), 185 patients (61%) received EVT and 116 (39%) received medical management. In adjusted analyses, EVT was associated with better functional independence (38% vs control, 10%; inverse probability treatment weighting adjusted odds ratio [IPTW aOR], 4.56; 95% CI, 2.28-9.09; P \u3c .001) despite increased odds of sICH (10.1% for EVT vs 1.7% for control; IPTW aOR, 10.65; 95% CI, 2.19-51.69; P = .003). This association persisted after PS-based matching on (1) clinical characteristics and ASPECTS (EVT, 35%, vs control, 19%; aOR, 3.14; 95% CI, 1.02-9.72; P = .047); (2) clinical characteristics and perfusion parameters (EVT, 35%, vs control, 17%; aOR, 4.17; 95% CI, 1.15-15.17; P = .03); and (3) clinical characteristics, ASPECTS, and perfusion parameters (EVT, 45%, vs control, 21%; aOR, 4.39; 95% CI, 1.04-18.53; P = .04). Patients receiving EVT had lower odds of mortality (26%) compared with those in the control group (41%; IPTW aOR, 0.49; 95% CI, 0.27-0.89; P = .02). CONCLUSIONS AND RELEVANCE: In this study of treatment beyond 24 hours of last known well, EVT was associated with higher odds of functional independence compared with medical management, with consistent results obtained in PS-matched subpopulations and patients with presence of mismatch, despite increased odds of sICH. Our findings support EVT feasibility in selected patients beyond 24 hours. Prospective studies are warranted for confirmation

    Association of Endovascular Thrombectomy vs Medical Management With Functional and Safety Outcomes in Patients Treated Beyond 24 Hours of Last Known Well: The SELECT Late Study

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    IMPORTANCE: The role of endovascular thrombectomy is uncertain for patients presenting beyond 24 hours of the time they were last known well. OBJECTIVE: To evaluate functional and safety outcomes for endovascular thrombectomy (EVT) vs medical management in patients with large-vessel occlusion beyond 24 hours of last known well. DESIGN, SETTING, AND PARTICIPANTS: This retrospective observational cohort study enrolled patients between July 2012 and December 2021 at 17 centers across the United States, Spain, Australia, and New Zealand. Eligible patients had occlusions in the internal carotid artery or middle cerebral artery (M1 or M2 segment) and were treated with EVT or medical management beyond 24 hours of last known well. INTERVENTIONS: Endovascular thrombectomy or medical management (control). MAIN OUTCOMES AND MEASURES: Primary outcome was functional independence (modified Rankin Scale score 0-2). Mortality and symptomatic intracranial hemorrhage (sICH) were safety outcomes. Propensity score (PS)-weighted multivariable logistic regression analyses were adjusted for prespecified clinical characteristics, perfusion parameters, and/or Alberta Stroke Program Early CT Score (ASPECTS) and were repeated in subsequent 1:1 PS-matched cohorts. RESULTS: Of 301 patients (median [IQR] age, 69 years [59-81]; 149 female), 185 patients (61%) received EVT and 116 (39%) received medical management. In adjusted analyses, EVT was associated with better functional independence (38% vs control, 10%; inverse probability treatment weighting adjusted odds ratio [IPTW aOR], 4.56; 95% CI, 2.28-9.09; P \u3c .001) despite increased odds of sICH (10.1% for EVT vs 1.7% for control; IPTW aOR, 10.65; 95% CI, 2.19-51.69; P = .003). This association persisted after PS-based matching on (1) clinical characteristics and ASPECTS (EVT, 35%, vs control, 19%; aOR, 3.14; 95% CI, 1.02-9.72; P = .047); (2) clinical characteristics and perfusion parameters (EVT, 35%, vs control, 17%; aOR, 4.17; 95% CI, 1.15-15.17; P = .03); and (3) clinical characteristics, ASPECTS, and perfusion parameters (EVT, 45%, vs control, 21%; aOR, 4.39; 95% CI, 1.04-18.53; P = .04). Patients receiving EVT had lower odds of mortality (26%) compared with those in the control group (41%; IPTW aOR, 0.49; 95% CI, 0.27-0.89; P = .02). CONCLUSIONS AND RELEVANCE: In this study of treatment beyond 24 hours of last known well, EVT was associated with higher odds of functional independence compared with medical management, with consistent results obtained in PS-matched subpopulations and patients with presence of mismatch, despite increased odds of sICH. Our findings support EVT feasibility in selected patients beyond 24 hours. Prospective studies are warranted for confirmation

    Rights and representation support justice across aquatic food systems

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    Injustices are prevalent in food systems, where the accumulation of vast wealth is possible for a few, yet one in ten people remain hungry. Here, for 194 countries we combine aquatic food production, distribution and consumption data with corresponding national policy documents and, drawing on theories of social justice, explore whether barriers to participation explain unequal distributions of benefits. Using Bayesian models, we find economic and political barriers are associated with lower wealth-based benefits; countries produce and consume less when wealth, formal education and voice and accountability are lacking. In contrast, social barriers are associated with lower welfare-based benefits; aquatic foods are less affordable where gender inequality is greater. Our analyses of policy documents reveal a frequent failure to address political and gender-based barriers. However, policies linked to more just food system outcomes centre principles of human rights, specify inclusive decision-making processes and identify and challenge drivers of injustice
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