1,042 research outputs found

    "Girl You Better Apply to Teachers' College": The History of Black Women Educators in Ontario, 1940s - 1980s

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    Girl You Better Apply to Teachers College examines the role of black women educators in Ontario from the 1940s to the 1980s. In an attempt to contribute to historical analysis on black identity, citizenship and racial difference in Canada, this dissertation investigates the ways in which black Canadian women confronted and navigated socially constructed boundaries of racial alienation, limited institutional support and inequality within Ontario school systems. In post-World War II Canada, black womens experiences in the teaching profession served as sites of struggle and contestation in a myriad of ways. Their presence as racialized educators, though smaller in number, represented the various ways in which black women disrupted mainstream notions of education in Ontario and challenged Canadian nationhood more broadly. This dissertation project argues that black women teachers engagement with Ontarios education system was comprised of a set of difficult, messy and complex processes; beginning with access to education, their ability to get into teachers college, the constant questioning of their professional status and the material realities that shaped their choices inside Ontario schools, black women teachers worked to prove their legitimacy and dedication to the vocation. At a time when education was used to teach young pupils how to be good moral citizens, black womens presence within these schooling institutions served to challenge the ways in which education was imparted and also revealed a system ill-equipped to deal with its changing student population. Largely using oral interviews, school board minutes, newspapers, yearbooks, and community records, Girl You Better Apply to Teachers College argues that black women educators sense of belonging in the professional sphere circumvented subtle and overt forms of racial and social exclusion in Ontario schools. In an effort to locate themselves within the Canadian national narrative, black female educators navigated concepts of citizenship and created a new kind of belonging that was parallel to and, at times, intersected with concepts of Canadian statehood

    TRAUMA AND STRESSOR-RELATED DISORDERS AMONG INTERNALLY DISPLACED PERSONS IN THE FEDERAL CAPITAL TERRITORY, ABUJA

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    This paper assesses stress and trauma-related disorders among the Internally Displaced Persons in the Federal Capital Territory, Abuja, Nigeria. In its methodology, the study took a descriptive approach. A convenient sample of 300 participants were drawn from each of the four officially recognized camps in the FCT making a total sample of 900 participants for this study. Face-face interview was conducted using interviewer administered structured questionnaire. Two additional research assistants and two Hausa interpreters were recruited for this study. The response rate was 100 percent. Anxiety, adjustment and attachment disorders were most prevalent in this study. Traumatic stress disorders were higher in respondents aged 37-58, and the unemployed. The interview was face-face and psychological tools like PHQ-9, PHQ-GAD, PHQ-SADS were used. Findings showed that a large proportion of the respondents are less educated, 94% of respondents were unemployed as at the time of this study. (67%) and those separated from spouses and family as a result of Boko-harm attacks. Recommendation made was that getting timely help and support may prevent normal stress reactions from getting worse and developing into PTS

    Routing of airplanes to two runways: monotonicity of optimal controls

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    We consider the problem of routing incoming airplanes to two runways of an airport. Due to air turbulence, the necessary separation time between two successive landing operations depends on the types of the airplanes. When viewed as a queueing problem, this means that we have dependent service times. The aim is to minimise waiting times of aircrafts. We consider here a model where arrivals form a stochastic process and where the decision maker does not know anything about future arrivals. We formulate this as a problem of stochastic dynamic programming and investigate monotonicity of optimal routing strategies with respect e.g. to the workload of the runways. We show that an optimal strategy is monotone (i.e. of switching type) only in a restricted case where decisions depend on the state of the runways only and not on the type of the arriving aircraft. Surprisingly, in the more realistic case where this type is also known to the decision maker, monotonicity need not hold

    On the waiting time of arriving aircrafts and the capacity of airports with one or two runways

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    In this paper we examine a model for the landing procedure of aircrafts at an airport. The characteristic feature here is that due to air turbulence the safety distance between two landing aircrafts depends on the types of these two machines. Hence, an eficient routing of the aircraft to two runways may reduce their waiting time. First, we use M/SM/1 queues (with dependent service times) to model a single runway. We give the stability condition and a formula for the average waiting time of the aircrafts. Moreover, we derive easy to compute bounds on the waiting times by comparison to simpler queuing systems. In particular we study the effect of neglecting the dependency of the service times when using M/G/1-models. We then consider the case of two runways with a number of heuristic routing strategies such as coin flipping, type splitting, Round Robin and variants of the join-the-least-load rule. These strategies are analyzed and compared numerically with respect to the average delay they cause. It turns out that a certain modication of join-the-least-load gives the best results

    Appraisal of Natural Durability of a Lesser – Known Boscia anguistifolia (A. Rich) Wood Using Ground Contact Test

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    The optimal utilization of lesser-known wood species is dependent on their natural durability. In this study, the natural durability of a lesser-known wood species (Boscia anguistifolia) using ground contact test was carried out. Wood blocks of Boscia anguistifolia and Ceiba petandra (reference species) with dimensions of 20 x 20 x 300 mm were obtained from the axial and radial direction of the trees. The wood blocks were conditioned and their moisture content determined before exposure to ground contact for 12 weeks after which their weight loss was determined. Data obtained were analysed using analysis of variance (ANOVA) at 0.05 probability level. The moisture content of B. anguistifolia and C. petandra ranged from 12.80 – 18.02 % and 12.73- 16.63%, respectively while the weight loss of B. anguistifolia and C. petandra ranged from 5.10 – 69.11% and 37 – 50 % respectively along the axial position. It was observed that the core wood in the base portion of B. anguistifolia has the lowest weight loss value of 5.10% while the reference species has a value of 39.73%. Conclusively, B. anguistifolia is moderately durable at the base part of the species when compared with the reference non-durable species used in this study

    Greece’s Three-Act Tragedy:A Simple Model of Grexit vs. Staying Afloat inside the Single Currency Area

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    Against the backdrop of the Greek three-act tragedy, we present a theoretical framework for studying Greece’s recent debt and currency crisis. The model is built on two essential blocks: first, erratic macroeconomic policymaking in Greece is described using a stochastic regimeswitching model; second, the euro area governments’ responses to uncertain macroeconomic policies in Greece are considered. The model’s mechanism and assumptions allow either for a Grexit from the euro area or, conversely, the avoidance of Greece’s default against its creditors. The model also offers useful guidance to understand key drivers of the long-winded negotiations between the Syiza government and the euro area governments

    NO2 VCD Stratospheric trends Hemispheric and latitudinal dependence

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    Presentación realizada para el 7th International DOAS Workshop celebrado en Bruselas los días 6-8 de julio de 2015Twenty years of stratospheric NO2 VCD data from ground-based zenith DOAS instruments have been used for trend analysis. Spectrometers either NDACC qualified or under evaluation cover Subtropical latitudes in Northern Hemisphere (Izaña, 28ºN), and Southern Antarctic (Marambio, 64ºS) and SubAntarctic (Ushuaia, 55ºS) regions. The multiple linear regression method includes annual, semiannual, quarterly, solar activity cycle, stratospheric aerosols, QBO and NAO proxies. The instruments settings follow the NDACC recommendations for NO2 measurements and the same AMF code. Results show a mean am/pm positive trend of + 7.9% at the 99% confidence level in the Northern Hemisphere station whereas the trends are negative in the Southern Hemisphere ones (-9.8% Ushuaia, -14.9% Marambio). From comparison with FTIR data, it is estimated that the changes are restricted to the lower stratosphere (15-30km) suggesting a dynamic origin of the trend. MIPAS NOy on a global scale shows a similar feature with a redistribution of the nitrogen family within the lower stratosphere

    HOCl chemistry in the Antarctic stratospheric vortex 2002, as observed with the Michelson interferometer for passive atmospheric sounding (MIPAS)

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    In the 2002 Antarctic polar vortex enhanced HOCl mixing ratios were detected by the Michelson Interferometer for Passive Atmospheric Sounding both at altitudes of around 35 km (1000K potential temperature), where HOCl abundances are ruled by gas phase chemistry and at around 18–24 km (475–625 K), which belongs to the altitude domain where heterogeneous chlorine chemistry is relevant. At altitudes of 33 to 40 km polar vortex HOCl mixing ratios were found to be around 0.14 ppbv as long as the polar vortex was intact, centered at the pole, and thus received relatively little sunlight. This is the altitude region where in midlatitudinal and tropic atmospheres peak HOCl mixing ratios significantly above 0.2 ppbv (in terms of daily mean values) are observed. After deformation and displacement of the polar vortex in the course of a major warming, ClO-rich vortex air was more exposed to sunlight, where enhanced HOx abundances led to largely increased HOCl mixing ratios (up to 0.3 ppbv), exceeding typical midlatitudinal and tropical amounts significantly. The HOCl increase was preceded by an increase of ClO. Model runs could reproduce these measurements only when the Stimpfle et al. (1979) rate constant for the reaction ClO+HO2→HOCl+O2 was used but not with the current JPL recommendation. At an altitude of 24 km, HOCl mixing ratios of up to 0.15 ppbv were detected. This HOCl enhancement, which is already visible in 18 September data, is attributed to heterogeneous chemistry, which is in agreement with observations of polar stratospheric clouds. The measurements were compared to a model run where no polar stratospheric clouds appeared during the observation period. The fact that HOCl still was produced in the model run suggests that a significant part of HOCl was generated from ClO rather than directly via heterogeneous reaction. Excess ClO, lower ClONO2 and earlier loss of HOCl in the measurements are attributed to ongoing heterogeneous chemistry which is not reproduced by the model. On 11 October, polar vortex mean daytime mixing ratios were only 0.03 ppbv

    Life Beyond the Solar System: Space Weather and Its Impact on Habitable Worlds

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    The search of life in the Universe is a fundamental problem of astrobiology and a major priority for NASA. A key area of major progress since the NASA Astrobiology Strategy 2015 (NAS15) has been a shift from the exoplanet discovery phase to a phase of characterization and modeling of the physics and chemistry of exoplanetary atmospheres, and the development of observational strategies for the search for life in the Universe by combining expertise from four NASA science disciplines including heliophysics, astrophysics, planetary science and Earth science. The NASA Nexus for Exoplanetary System Science (NExSS) has provided an efficient environment for such interdisciplinary studies. Solar flares, coronal mass ejections and solar energetic particles produce disturbances in interplanetary space collectively referred to as space weather, which interacts with the Earth upper atmosphere and causes dramatic impact on space and ground-based technological systems. Exoplanets within close in habitable zones around M dwarfs and other active stars are exposed to extreme ionizing radiation fluxes, thus making exoplanetary space weather (ESW) effects a crucial factor of habitability. In this paper, we describe the recent developments and provide recommendations in this interdisciplinary effort with the focus on the impacts of ESW on habitability, and the prospects for future progress in searching for signs of life in the Universe as the outcome of the NExSS workshop held in Nov 29 - Dec 2, 2016, New Orleans, LA. This is one of five Life Beyond the Solar System white papers submitted by NExSS to the National Academy of Sciences in support of the Astrobiology Science Strategy for the Search for Life in the Universe.Comment: 5 pages, the white paper was submitted to the National Academy of Sciences in support of the Astrobiology Science Strategy for the Search for Life in the Univers

    Optimization of the All-D peptide D3 for Aβ oligomer elimination

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    The aggregation of amyloid-{beta} (A{beta}) is postulated to be the crucial event in Alzheimer's disease (AD). In particular, small neurotoxic A{beta} oligomers are considered to be responsible for the development and progression of AD. Therefore, elimination of thesis oligomers represents a potential causal therapy of AD. Starting from the well-characterized d-enantiomeric peptide D3, we identified D3 derivatives that bind monomeric A{beta}. The underlying hypothesis is that ligands bind monomeric A{beta} and stabilize these species within the various equilibria with A{beta} assemblies, leading ultimately to the elimination of A{beta} oligomers. One of the hereby identified d-peptides, DB3, and a head-to-tail tandem of DB3, DB3DB3, were studied in detail. Both peptides were found to: (i) inhibit the formation of Thioflavin T-positive fibrils; (ii) bind to A{beta} monomers with micromolar affinities; (iii) eliminate A{beta} oligomers; (iv) reduce A{beta}-induced cytotoxicity; and (v) disassemble preformed A{beta} aggregates. The beneficial effects of DB3 were improved by DB3DB3, which showed highly enhanced efficacy. Our approach yielded A{beta} monomer-stabilizing ligands that can be investigated as a suitable therapeutic strategy against AD
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