1,925 research outputs found

    Leveraging community-based innovations during COVID-19 to strengthen the Haitian school system

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    War, natural disasters, and other emergencies regularly disrupt children’s education in developing countries. The digital divide has long since affected low-resource and rural schools’ responses to crises that necessitate distance learning, often excluding children in remote and rural parts of countries from internet-dependent online learning programmes. In no place is this truer than in Haiti where, prior to August 2020, political unrest combined with the COVID-19 pandemic caused learners to miss 60% of their scheduled days in the 2019–2020 school year with only 45% of Haitian households having access to a power source, let alone internet or a smart device, that would enable them to participate in online learning. This study presents findings from exploratory research on the readiness of the Haitian education system to withstand crises and the impact of COVID-19 on the system and its learners. Through analyses of secondary data and semi-structured interviews with a variety of education stakeholders, the research reveals gaps in the system’s readiness; identifies key challenges prompted by school closures in Haiti and shares a handful of innovative responses developed to respond to these challenges. Findings indicate that the COVID-19 health crisis has not created the need for educational reform in Haiti, but rather, by exacerbating pre-existing gaps and frailties within the system, the pandemic has heightened the urgency with which educational reform must be pursued. Salient gaps include a significant digital divide, financial instability and inattention to learning adjacent needs such as nutrition and psychosocial health for parents and children alike. While this initial research has exposed a series of significant gaps and inequalities in the Haitian education system, moving forward, more comprehensive research is needed to determine how such inequalities can be most effectively addressed. Although the Haitian government has a key role to play in addressing these inequalities, findings from this study reveal that governmental responses to COVID-19 school closures and broader digital learning inequalities, were ineffective in their reach and did not reflect the majority of Haitian learners and their families’ realities. Findings also identify numerous innovations and assets on the part of non-governmental actors striving to address these gaps. However, these mechanisms were limited in scope and lacked the coordination among one another and the government that would be required to have scalable or measurable impact. Therefore, more research is needed to determine what the most successful mechanisms for addressing inequalities in the Haitian education system are and how they can be most effectively leveraged and scaled to create a more resilient education system moving forward

    Three-dimensional tomographic reconstruction of mesospheric airglow structures using two-station ground-based image measurements

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    A new methodology is presented to create two-dimensional (2D) and three-dimensional (3D) tomographic reconstructions of mesospheric airglow layer structure using two-station all-sky image measurements. A fanning technique is presented that produces a series of cross-sectional 2D reconstructions, which are combined to create a 3D mapping of the airglow volume. The imaging configuration is discussed and the inherent challenges of using limited-angle data in tomographic reconstructions have been analyzed using artificially generated imaging objects. An iterative reconstruction method, the partially constrained algebraic reconstruction technique (PCART), was used in conjunction with a priori information of the airglow emission profile to constrain the height of the imaged region, thereby reducing the indeterminacy of the inverse problem. Synthetic projection data were acquired from the imaging objects and the forward problem to validate the tomographic method and to demonstrate the ability of this technique to accurately reconstruct information using only two ground-based sites. Reconstructions of the OH airglow layer were created using data recorded by all-sky CCD cameras located at Bear Lake Observatory, Utah, and at Star Valley, Wyoming, with an optimal site separation of ~100 km. The ability to extend powerful 2D and 3D tomographic methods to two-station ground-based measurements offers obvious practical advantages for new measurement programs. The importance and applications of mesospheric tomographic reconstructions in airglow studies, as well as the need for future measurements and continued development of techniques of this type, are discussed. © 2012 Optical Society of America

    Higher hematocrit improves cerebral outcome after deep hypothermic circulatory arrest

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    AbstractBackground: Various degrees of hemodilution are currently in clinical use during deep hypothermic circulatory arrest to counteract deleterious rheologic effects linked with brain injury by previous reports. Material and methods: Seventeen piglets were randomly assigned to three groups. Group I piglets (n = 7) received colloid and crystalloid prime (hematocrit < 10%), group II piglets (n = 5) received blood and crystalloid prime (hematocrit 20%), group III piglets (n = 5) received blood prime (hematocrit 30%). All groups underwent 60 minutes of deep hypothermic circulatory arrest at 15º C. with continuous magnetic resonance spectroscopy and near-infrared spectroscopy Neurologic recovery was evaluated for 4 days (neurologic deficit score 0, normal, to 500, brain death; overall performance category 1, normal, to 5, brain death). Neurohistologic score (0, normal, to 5+, necrosis) was assessed after the animals were euthanized on day 4. Results: Group I had significant loss of phosphocreatine and intracellular acidosis during early cooling (phosphocreatine in group I, 86.3% ± 26.8%; group II, 117.3% ± 8.6%; group III, 110.9% ± 2.68%; p = 0.0008; intracellular pH in group I, 6.95 ± 0.18; group II, 7.28 ± 0.04; group III, 7.49 ± 0.04; p = 0.0048). Final recovery was the same for all groups. Cytochrome aa3 was more reduced in group I during deep hypothermic circulatory arrest than in either of the other groups (group I, -43.6 ± 2.6; group II, -16.0 ± 5.2; group III, 1.3 ± 3.1; p < 0.0001). Neurologic deficit score was best preserved in group III (p < 0.05 group II vs group III) on the first postoperative day, although this difference diminished with time and all animals were neurologically normal after 4 days. Histologic assessment was worst among group I in neocortex area (group I, 1.33 ± 0.3; group II, 0.22 ± 0.1; group III, 0.40 ± 0.2, p < 0.05, group I vs group II; p = 0.0287, group I vs group III). Conclusion: Extreme hemodilution during cardiopulmonary bypass may cause inadequate oxygen delivery during early cooling. The higher hematocrit with a blood prime is associated with improved cerebral recovery after deep hypothermic circulatory arrest. (J Thorac Cardiovasc Surg 1996;112:1610-21

    A novel sialyl lewis x analog attenuates cerebral injury after deep hypothermic circulatory arrest

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    AbstractBackground: The initial step in the inflammatory process, which can be initiated by cardiopulmonary bypass and by ischemia/reperfusion, is mediated by interactions between selectins on endothelial cells and on neutrophils. We studied the effects of selectin blockade using a novel Sialyl Lewis X analog (CY-1503) on recovery after deep hypothermic circulatory arrest in a piglet model. Methods: Twelve Yorkshire piglets were subjected to cardiopulmonary bypass, 30 minutes of cooling, 100 minutes of circulatory arrest at 15°C, and 40 minutes of rewarming. Five animals received a bolus of 60 mg/kg of CY-1503 and an infusion (3 mg/kg per hour) for 24 hours from reperfusion (group O), and 7 randomly selected control piglets received saline solution (group C). Body weight and total body water content were evaluated 3 hours and 24 hours after reperfusion by a bio-impedance technique. Neurologic recovery of animals was evaluated daily by neurologic deficit score (0 = normal, 500 = brain death) and overall performance categories (1 = normal, 5 = brain death). The brain was fixed in situ on the fourth postoperative day and examined by histologic score (0 = normal, 5+ = necrosis) in a blinded fashion. Results: Two of 7 animals in group C died. The neurologic deficit score was significantly lower in group O than in group C (postoperative day 1, P < .001; postoperative day 2, P = .02). The overall performance category was significantly lower in group O than in group C on postoperative day 2 (P = .01). Percentage total body water after cardiopulmonary bypass was significantly higher in group C than in group O (P = .03). Histologic score tended to be higher in group C than in group O, but this difference did not reach statistical significance (group O = 0.5 ± 0.7; group C = 1.3 ± 1.9). Conclusion: Blockade of selectin adhesion molecules by saturation with a Sialyl Lewisxanalog accelerates recovery after 100 minutes of deep hypothermic circulatory arrest in a piglet survival model. (J Thorac Cardiovasc Surg 1999; 117:1204-11

    Use of machine learning techniques to model wind damage to forests

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    This paper tested the ability of machine learning techniques, namely artificial neural networks and random forests, to predict the individual trees within a forest most at risk of damage in storms. Models based on these techniques were developed individually for both a small forest area containing a set of 29 permanent sample plots that were damaged in Storm Martin in December 1999, and from a much larger set of 235 forest inventory data damaged in Storm Klaus in January 2009. Both data sets are within the Landes de Gascogne Forest in Nouvelle Aquitaine, France. The models were tested both against the data from which they were developed, and against the data set from the other storm. For comparison with an earlier study using the same data, logistic regression models were also developed. In addition, the ability of machine learning techniques to substitute for a mechanistic wind damage risk model by training them with previous mechanistic model predictions was tested. All models were accurate at identifying whether trees would be damaged or not damaged but the random forests models were more accurate, had higher discriminatory power, and were almost totally unaffected by the removal of any individual input variable. However, if all information relating to a stand was removed the random forests model lost accuracy and discriminatory power. The other models were similarly affected by the removal of all site information but none of the models were affected by removal of all tree information, suggesting that damage in the Landes de Gascogne Forest occurs at stand scale and is not controlled by individual tree characteristics. The models developed with the large comprehensive database were also accurate in identifying damaged trees when applied to the small forest data damaged in the earlier storm. However, none of the models developed with the smaller forest data set could successfully discriminate between damaged and undamaged trees when applied across the whole landscape. All models were very successful in replicating the predictions of the mechanistic wind risk model and using them as a substitute for the mechanistic model predictions of critical wind speed did not affect the damage model results. Overall the results suggest that random forests provide a significant advantage over other statistical modelling techniques and the random forest models were found to be more robust in their predictions if all input variables were not available. In addition, the ability to replace the mechanistic wind damage model suggests that random forests could provide a powerful tool for damage risk assessment at the stand or single tree level over large regions and provide rapid assessment of the impact of different management strategies or be used in the development of optimised forest management with multiple objectives and constraints including the risk of wind damage

    Investigating Gravity Waves in Polar Mesospheric Clouds Using Tomographic Reconstructions of AIM Satellite Imagery

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    This research presents the first application of tomographic techniques for investigating gravity wave structures in polar mesospheric clouds (PMCs) imaged by the Cloud Imaging and Particle Size instrument on the NASA AIM satellite. Albedo data comprising consecutive PMC scenes were used to tomographically reconstruct a 3‐D layer using the Partially Constrained Algebraic Reconstruction Technique algorithm and a previously developed “fanning” technique. For this pilot study, a large region (760 × 148 km) of the PMC layer (altitude ~83 km) was sampled with a ~2 km horizontal resolution, and an intensity weighted centroid technique was developed to create novel 2‐D surface maps, characterizing the individual gravity waves as well as their altitude variability. Spectral analysis of seven selected wave events observed during the Northern Hemisphere 2007 PMC season exhibited dominant horizontal wavelengths of ~60–90 km, consistent with previous studies. These tomographic analyses have enabled a broad range of new investigations. For example, a clear spatial anticorrelation was observed between the PMC albedo and wave‐induced altitude changes, with higher‐albedo structures aligning well with wave troughs, while low‐intensity regions aligned with wave crests. This result appears to be consistent with current theories of PMC development in the mesopause region. This new tomographic imaging technique also provides valuable wave amplitude information enabling further mesospheric gravity wave investigations, including quantitative analysis of their hemispheric and interannual characteristics and variations

    Gender Differences in Russian Colour Naming

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    In the present study we explored Russian colour naming in a web-based psycholinguistic experiment (http://www.colournaming.com). Colour singletons representing the Munsell Color Solid (N=600 in total) were presented on a computer monitor and named using an unconstrained colour-naming method. Respondents were Russian speakers (N=713). For gender-split equal-size samples (NF=333, NM=333) we estimated and compared (i) location of centroids of 12 Russian basic colour terms (BCTs); (ii) the number of words in colour descriptors; (iii) occurrences of BCTs most frequent non-BCTs. We found a close correspondence between females’ and males’ BCT centroids. Among individual BCTs, the highest inter-gender agreement was for seryj ‘grey’ and goluboj ‘light blue’, while the lowest was for sinij ‘dark blue’ and krasnyj ‘red’. Females revealed a significantly richer repertory of distinct colour descriptors, with great variety of monolexemic non-BCTs and “fancy” colour names; in comparison, males offered relatively more BCTs or their compounds. Along with these measures, we gauged denotata of most frequent CTs, reflected by linguistic segmentation of colour space, by employing a synthetic observer trained by gender-specific responses. This psycholinguistic representation revealed females’ more refined linguistic segmentation, compared to males, with higher linguistic density predominantly along the redgreen axis of colour space

    Технологические решения для строительства разведочной вертикальной скважины глубиной 2520 метров на нефтегазовом месторождении (Красноярский край)

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    Объектом исследования является нефтегазовом месторождение Красноярского края. Цель работы - проектирование технологических процессов бурения и заканчивания скважины. В процессе работы был составлен технологический проект на строительство разведочной вертикальной скважины глубиной 2520 метров на нефтегазовом месторождении Красноярского края. В результате исследования были спроектированы технологические решения строительство скважины. Описаны конструктивные, технологические и технеко - экономические показатели.The object of study is the oil and gas condensate field of the Krasnoyarsk Territory. The purpose of the work is the design of technological processes for drilling and well completion. In the process, a technological project was drawn up for the construction of an exploratory vertical well with a depth of 2520 meters at the oil and gas condensate field in the Krasnoyarsk Territory. As a result of the study, technological solutions for well construction were designed. The constructive, technological and techno-economic indicators are described

    BRCA2 polymorphic stop codon K3326X and the risk of breast, prostate, and ovarian cancers

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    Background: The K3326X variant in BRCA2 (BRCA2*c.9976A&gt;T; p.Lys3326*; rs11571833) has been found to be associated with small increased risks of breast cancer. However, it is not clear to what extent linkage disequilibrium with fully pathogenic mutations might account for this association. There is scant information about the effect of K3326X in other hormone-related cancers. Methods: Using weighted logistic regression, we analyzed data from the large iCOGS study including 76 637 cancer case patients and 83 796 control patients to estimate odds ratios (ORw) and 95% confidence intervals (CIs) for K3326X variant carriers in relation to breast, ovarian, and prostate cancer risks, with weights defined as probability of not having a pathogenic BRCA2 variant. Using Cox proportional hazards modeling, we also examined the associations of K3326X with breast and ovarian cancer risks among 7183 BRCA1 variant carriers. All statistical tests were two-sided. Results: The K3326X variant was associated with breast (ORw = 1.28, 95% CI = 1.17 to 1.40, P = 5.9x10- 6) and invasive ovarian cancer (ORw = 1.26, 95% CI = 1.10 to 1.43, P = 3.8x10-3). These associations were stronger for serous ovarian cancer and for estrogen receptor–negative breast cancer (ORw = 1.46, 95% CI = 1.2 to 1.70, P = 3.4x10-5 and ORw = 1.50, 95% CI = 1.28 to 1.76, P = 4.1x10-5, respectively). For BRCA1 mutation carriers, there was a statistically significant inverse association of the K3326X variant with risk of ovarian cancer (HR = 0.43, 95% CI = 0.22 to 0.84, P = .013) but no association with breast cancer. No association with prostate cancer was observed. Conclusions: Our study provides evidence that the K3326X variant is associated with risk of developing breast and ovarian cancers independent of other pathogenic variants in BRCA2. Further studies are needed to determine the biological mechanism of action responsible for these associations
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