959 resultados para Volatilità implicita, formula di Black and Scholes


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Objective - To investigate visual habituation – a measure of visual cortical excitability – in photosensitive patients in pediatric age and compare the findings with a matched sample with idiopathic generalized epilepsies without photosensitivity and with normally developing children. Methods - We presented a full-field black-and-white checkerboard pattern, at 3 reversal/s with 100% contrast binocularly for 600 consecutive trials and measured the N75–P100 and P100–N145 pattern-reversal visual evoked potential inter-peak amplitudes and N75, P100, N145 latencies for the six blocks of 100 responses. As a measure of habituation we used the slope of the linear regression line of the N75–P100 and P100–N145 peak-to-peak amplitudes. The slope of the linear regression line of the N75–P100 and P100–N145 latencies was also analyzed. Results - Statistical analysis revealed significant differences between the three groups in the slope index of N75–P100 PR-VEP amplitude, with increased or constant amplitude in the PS group compare to the IGE and ND across the six blocks. Conclusions - Our results support the notion that photosensitivity is associated with altered control of excitatory and inhibitory cortical processes. The causal relationship between habituation deficit and photo-paroxysmal response needs to be further investigated with longitudinal studies. Significance This study supports the hypothesis that suppression of PR-VEP is a sensitive intermediate phenotype, which discriminates patients with photosensitivity from those with generalized epilepsies in pediatric age.

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This study aimed to assess the effectiveness of a novel, community-based weight management programme delivered through general practitioner (GP) practices and community pharmacies in one city in the United Kingdom. This study used a non-randomized, retrospective, observational comparison of clinical data collected by participating GP practices and community pharmacies. Subjects were 451 overweight or obese men and women resident in areas of high socioeconomic deprivation (82% from black and minority ethnic groups, 86% women, mean age: 41.1 years, mean body mass index [BMI]: 34.5 kg m−2). Weight, waist circumference and BMI at baseline, after 12 weeks and after 9 months were measured. Costs of delivery were also analysed. Sixty-four per cent of participants lost weight after the first 12 weeks of the My Choice Weight Management Programme. There was considerable dropout. Mean percentage weight loss (last observation carried forward) was 1.9% at 12 weeks and 1.9% at final follow-up (9 months). There was no significant difference in weight loss between participants attending GP practices and those attending pharmacies at both 12 weeks and at final follow-up. Costs per participant were higher via community pharmacy which was attributable to better attendance at sessions among community pharmacy participants than among GP participants. The My Choice Weight Management Programme produced modest reductions in weight at 12 weeks and 9 months. Such programmes may not be sufficient to tackle the obesity epidemic.

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2000 Mathematics Subject Classification: 62H12, 62P99

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This longitudinal study provides a detailed description of the transition in the Bahamas from British colony to independent country. It analyzes the ongoing process of legitimation and delegitimation of Bahamian political parties and of the transfer of authority from the white minority to the black majority. It is a story of social and political struggles that take place within the quarter century following World War II. These struggles are analyzed within a theoretical framework which focuses on the meaning of symbols used to support claims to authority, and/or which function to delegitimize alternative claims. Specifically, this study looks at the delegitimization of the institutions of colonialism and the concurrent profession of symbols to support both independence and a fully enfranchised democracy in the Bahamas. ^ The research methodology includes an extensive analysis of official British colonial documents, private governmental dispatches, and contemporaneous newspaper articles. The sources were primarily the Public Records Office of Great Britain; the Archives of the Bahamas; and the Institute for Social and Economic Research, University of the West Indies. Secondary literature on civil rights, political science, religion, Black Nationalism, corruption, social theory, and popular culture was studied. Two hundred days of participant observation, spread over seven years of study, resulted in notes from which information was gleaned. During that time, seventeen open-ended interviews with a cross section of Bahamians (male and female, black and white) who lived through this period were recorded, information from which was also incorporated. ^ A detailed description of the socio-historical process, and an analysis of data, demonstrates how the black majority's desire for political representation, and future independence, pressured Great Britain to come into line with the desires of the majority of Bahamians. The symbolic universe that had historically divided white from black now urged dramatic social and political change. ^ The documents and testimonials studied demonstrate how symbols and symbolic events supported and/or undercut the claims to legitimacy proffered by different groups in the Bahamas in their respective attempts to solidify their social and political position within the society. ^

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The use of canines as a method of detection of explosives is well established worldwide and those applying this technology range from police forces and law enforcement to humanitarian agencies in the developing world. Despite the recent surge in publication of novel instrumental sensors for explosives detection, canines are still regarded by many to be the most effective real-time field method of explosives detection. However, unlike instrumental methods, currently it is difficult to determine detection levels, perform calibration of the canines' ability or produce scientifically valid quality control checks. Accordingly, amongst increasingly strict requirements regarding forensic evidence admission such as Frye and Daubert, there is a need for better scientific understanding of the process of canine detection. ^ When translated to the field of canine detection, just like any instrumental technique, peer reviewed publication of the reliability, success and error rates, is required for admissibility. Commonly training is focussed towards high explosives such as TNT and Composition 4, and the low explosives such as Black and Smokeless Powders are added often only for completeness. ^ Headspace analyses of explosive samples, performed by Solid Phase Microextraction (SPME) paired with Gas Chromatography - Mass Spectrometry (GC-MS), and Gas Chromatography - Electron Capture Detection (GC-ECD) was conducted, highlighting common odour chemicals. The odour chemicals detected were then presented to previously trained and certified explosives detection canines, and the activity/inactivity of the odour determined through field trials and experiments. ^ It was demonstrated that TNT and cast explosives share a common odour signature, and the same may be said for plasticized explosives such as Composition C-4 and Deta Sheet. Conversely, smokeless powders were demonstrated not to share common odours. An evaluation of the effectiveness of commercially available pseudo aids reported limited success. The implications of the explosive odour studies upon canine training then led to the development of novel inert training aids based upon the active odours determined. ^

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Urban inequality has emerged as one of the dominant themes of modern life and globalization. More than three million people experienced homelessness in the United States last year; in Miami-Dade, more than 15,000 individuals were homeless. Surviving extreme poverty, and exiting or avoiding homelessness, involves negotiating a complex mix of public and private assistance. However, a range of factors influence what types of help are available and how they can be accessed. Frequently, larger social structures determine which resource are available, leaving many choices entirely out of the individual's control. For single men, who are ineligible for many benefits, homelessness can be difficult to avoid and even harder to exit. My study seeks to better understand how adult, minority men living in extreme poverty in Miami-Dade negotiate their daily survival. Specific research questions address: Do black and Hispanic men who are homeless or at risk of homelessness have different personal characteristics and different experiences in avoiding or exiting homelessness? How does Miami's response to extreme poverty/homelessness, including availability of public benefits and public and private service organizations, either maximize or constrain the choices available to this population? And, what is the actual experience of single, adult men who are homeless or at risk of homelessness, in negotiating their daily survival? A mixed methods approach combines quantitative survey data from 7,605 homeless men, with qualitative data from 54 semi-structured interviews incorporating the visual ethnography techniques of Photo Elicitation Interviewing. Results show the differences experienced by black and Hispanic men who are poor and homeless in Miami. Findings also highlight how the community's official and unofficial responses to homelessness intersect with the actual experiences of the persons targeted by the policies and programs, challenging preconceived notions regarding the lives of persons living in extreme poverty. It adds to the existing body of literature by focusing on the urban Miami context, emphasizing disparities amongst racial and ethnic groups. Findings are intended to provide an empirically grounded thesis that humanizes the subjects and illuminates their personal experiences, helping to inform public policy around the needs of extremely poor populations.

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Elemental analysis can become an important piece of evidence to assist the solution of a case. The work presented in this dissertation aims to evaluate the evidential value of the elemental composition of three particular matrices: ink, paper and glass. In the first part of this study, the analytical performance of LIBS and LA-ICP-MS methods was evaluated for paper, writing inks and printing inks. A total of 350 ink specimens were examined including black and blue gel inks, ballpoint inks, inkjets and toners originating from several manufacturing sources and/or batches. The paper collection set consisted of over 200 paper specimens originating from 20 different paper sources produced by 10 different plants. Micro-homogeneity studies show smaller variation of elemental compositions within a single source (i.e., sheet, pen or cartridge) than the observed variation between different sources (i.e., brands, types, batches). Significant and detectable differences in the elemental profile of the inks and paper were observed between samples originating from different sources (discrimination of 87–100% of samples, depending on the sample set under investigation and the method applied). These results support the use of elemental analysis, using LA-ICP-MS and LIBS, for the examination of documents and provide additional discrimination to the currently used techniques in document examination. In the second part of this study, a direct comparison between four analytical methods (µ-XRF, solution-ICP-MS, LA-ICP-MS and LIBS) was conducted for glass analyses using interlaboratory studies. The data provided by 21 participants were used to assess the performance of the analytical methods in associating glass samples from the same source and differentiating different sources, as well as the use of different match criteria (confidence interval (±6s, ±5s, ±4s, ±3s, ±2s), modified confidence interval, t-test (sequential univariate, p=0.05 and p=0.01), t-test with Bonferroni correction (for multivariate comparisons), range overlap, and Hotelling's T2 tests. Error rates (Type 1 and Type 2) are reported for the use of each of these match criteria and depend on the heterogeneity of the glass sources, the repeatability between analytical measurements, and the number of elements that were measured. The study provided recommendations for analytical performance-based parameters for µ-XRF and LA-ICP-MS as well as the best performing match criteria for both analytical techniques, which can be applied now by forensic glass examiners.

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Hispanics and other minority Americans are denied access to higher education by a system that needs structural reform. The purpose of the research was to determine whether creating Hispanic-serving land-grant colleges, similar to the Morrill land-grant colleges serving Black and Native Americans, might be an effective strategy to increase the access of Hispanic students to quality higher education. In addition to published materials, data was collected from a survey of Hispanic-serving institutions and extensive interviews with college presidents, government representatives, educational association leaders, and educational historians. ^ The research examined how existing land-grant college systems came into being and how they have evolved. A look at the functions of the land-grant systems serving Blacks and Native Americans revealed promising possibilities for a system that would include more Hispanics. Legal, fiscal, curricular, and organizational criteria were inferred from the existing systems. While none of the existing land-grant systems can be adapted to serve Hispanics or most other minorities outside their limited regions, each has elements that could be adapted by a new minority-serving system. A number of colleges already have features that could make them candidates for state designation as land-grant colleges. ^ The research suggests that a new federally funded system of Morrill land-grant colleges dedicated to serving all urban Americans, not just Hispanics, would do much to increase the numbers of Hispanic students and other racially and ethnically minority Americans in good quality higher educational institutions. An inclusive urban land-grant system would be politically feasible, whereas one meant to serve Hispanics alone would not. Because of their urban locations, these universities would serve large concentrations of minority citizens of all ethnic groups. ^ Finally, the basic elements of a strategic plan are presented for an educational organization to use for organizing leaders of minority educational associations, financing an initiative to lobby Congress, eliciting legislative and federal agency support, and securing the assistance of other educational, industrial, and special interest groups. The plan includes a suggested timetable for action. Recommendations are made for innovations that would make such a higher education system distinctive and would help meet important national needs. ^

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Every year, 16 million women aged 15 to 19 years give birth globally. Adolescent births account for 11% of all births globally and 23% of the overall burden of disability and diseases due to pregnancy and childbirth. In the United States, 750,000 adolescents (15-19 years) become pregnant each year, making the United States the developed country with the highest rates of adolescent pregnancy. The economic burden of adolescent pregnancy in the U. S. is $7-15 billion per year. Adolescent pregnancy brings risks associated with pregnancy induced hypertension, preterm infants, maternal and neonatal mortality. Social factors include poverty, low educational levels, alcohol, and drug use. Between 30-50% of adolescent mothers who have a first birth before age 18 years will have a second child within 12 to 24 months. Subsequent adolescent pregnancies compound fetal and maternal risks. Many vulnerable adolescent mothers succumb to external pressures and have a repeat adolescent pregnancy while others are able to overcome the challenges of an adolescent pregnancy and prevent a repeat adolescent pregnancy. This cross sectional survey designed study investigated the effects of resilience and social influences on contraceptive use or abstinence by Black and Hispanic adolescent parenting mothers to prevent a repeat adolescent pregnancy. 140 adolescent mothers were recruited from three postpartum units of a tertiary hospital system in Miami, Florida. The Wagnild and Young Resilience Scale and the Adolescent Social Influence Scale were used to measure resilience and social influences, respectively. Demographic data, length of labor, plan for contraceptive use or abstinence were measured by an investigator developed instrument. Point biserial correlation showed a significant positive correlation between Black adolescent mothers' resilience and contraceptive use (r =.366, p2(11, N=133) = 27.08, p =.004. (OR = .28). These results indicate a need for interventional strategies to maximize resilience in parenting adolescents to prevent a repeat adolescent pregnancy.

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Advanced Placement is a series of courses and tests designed to determine mastery over introductory college material. It has become part of the American educational system. The changing conception of AP was examined using critical theory to determine what led to a view of continual success. The study utilized David Armstrong's variation of Michel Foucault's critical theory to construct an analytical framework. Black and Ubbes' data gathering techniques and Braun and Clark's data analysis were utilized as the analytical framework. Data included 1135 documents: 641 journal articles, 421 newspaper articles and 82 government documents. ^ The study revealed three historical ruptures correlated to three themes containing subthemes. The first rupture was the Sputnik launch in 1958. Its correlated theme was AP leading to school reform with subthemes of AP as reform for able students and AP's gaining of acceptance from secondary schools and higher education. The second rupture was the Nation at Risk report published in 1983. Its correlated theme was AP's shift in emphasis from the exam to the course with the subthemes of AP as a course, a shift in AP's target population, using AP courses to promote equity, and AP courses modifying curricula. The passage of the No Child Left Behind Act of 2001 was the third rupture. Its correlated theme was AP as a means to narrow the achievement gap with the subthemes of AP as a college preparatory program and the shifting of AP to an open access program. ^ The themes revealed a perception that progressively integrated the program into American education. The AP program changed emphasis from tests to curriculum, and is seen as the nation's premier academic program to promote reform and prepare students for college. It has become a major source of income for the College Board. In effect, AP has become an agent of privatization, spurring other private entities into competition for government funding. The change and growth of the program over the past 57 years resulted in a deep integration into American education. As such the program remains an intrinsic part of the system and continues to evolve within American education. ^

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The concentration of C37-C39 long-chain alkenones and alkenes were determined in surface water and surface sediment samples from the subpolar waters of the Southern Ocean. Distributions of these compounds were similar in both sample sets indicating little differential degradation between or within compound classes. The relative amounts of the tri- to tetra-unsaturated C37 alkenones increased with increasing temperature for temperatures below 6°C similar to the di- and tri-unsaturated C37 alkenones. The C37 di-, tri-, and tetra-unsaturated methyl alkenones are used in paleotemperature calculations via the U37K and the U37K ratios. In these datasets, the relative abundances of the C37:2 and the C37.3 alkenones as a proportion of the total C37 alkenones were opposite and strongly related to temperature (the latter with more scatter), but the abundance of the C37:4 alkenone showed no relationship with temperature. The original definition of U37K includes the abundance of 37:4 in both the numerator and denominator, and thus it is perhaps not surprising that there is considerable scatter in the values obtained for U37K at low temperatures. Of the two, we suggest that U37K' is the better parameter for use in paleotemperature estimations, even in cold locations. U37K' values in the sediments fall on virtually the same regression line obtained for the water column samples of Sikes and Volkman (1993, doi:10.1016/0016-7037(93)90120-L), indicating that their calibration is suitable for use in Southern Ocean sediments. The comparison of water column data with sedimentary temperature estimates suggests that the alkenone distributions are dominated by contributions from the summer when the biomass of Emiliania huxleyi and presumably flux to the sediment, is expected to be high.

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Geochemical barrier zones play an important role in determining various physical systems and characteristics of oceans, e.g. hydrodynamics, salinity, temperature and light. In the book each of more than 30 barrier zones are illustrated and defined by physical, chemical and biological parameters. Among the topics discussed are processes of inflow, transformation and precipitation of the sedimentary layer of the open oceans and more restricted areas such as the Baltic, Black and Mediterranean Seas.

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We studied the grain-size, mineral and chemical compositions, physical properties, radiocarbon age, spore-pollen spectra, and diatom composition in sediments from Core PSh24-2537 sampled in the West Gotland Basin. Four lithological-stratigraphic units were distinguished: varved clays of the Baltic Ice Lake, black and black-gray (sulfide) clays of the Yoldian Sea, gray clays of Ancylus Lake, and greenish-gray sapropel-like littorine and post-littorine silts of the marine stage of Holocene. These units differ from each other both in their matter composition and in plant remains. In the littorine silts organic carbon concentra¬tion reached from 1.5 to 10.35%. Conditions of sediment accumulation and the stages of evolution of the West Gotland Basin over the post-glacial time are characterized.

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Acknowledgements The authors would like to thank staff at Marine Scotland Science Patricia White, Rebecca McIntosh, Julia Black and Mark Fordyce for their technical assistance and invaluable feedback on the project. Thanks also go to Alex Douglas at the University of Aberdeen for his advice on data analysis and statistics. For feedback on the manuscript thanks to Lesley McEvoy and Rhiannon Inkster at the NAFC Marine Centre. The study was supported by the Marine Collaborations Forum (MarCRF) which aims to develop cross-disciplinary research between the University of Aberdeen and Marine Scotland Science. Finally, thanks are also due to Scottish Fishermen's Trust for a student support bursary.

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Autism spectrum disorders (ASD) are complex heterogeneous neurodevelopmental disorders of an unclear etiology, and no cure currently exists. Prior studies have demonstrated that the black and tan, brachyury (BTBR) T+ Itpr3tf/J mouse strain displays a behavioral phenotype with ASD-like features. BTBR T+ Itpr3tf/J mice (referred to simply as BTBR) display deficits in social functioning, lack of communication ability, and engagement in stereotyped behavior. Despite extensive behavioral phenotypic characterization, little is known about the genes and proteins responsible for the presentation of the ASD-like phenotype in the BTBR mouse model. In this study, we employed bioinformatics techniques to gain a wide-scale understanding of the transcriptomic and proteomic changes associated with the ASD-like phenotype in BTBR mice. We found a number of genes and proteins to be significantly altered in BTBR mice compared to C57BL/6J (B6) control mice controls such as BDNF, Shank3, and ERK1, which are highly relevant to prior investigations of ASD. Furthermore, we identified distinct functional pathways altered in BTBR mice compared to B6 controls that have been previously shown to be altered in both mouse models of ASD, some human clinical populations, and have been suggested as a possible etiological mechanism of ASD, including "axon guidance" and "regulation of actin cytoskeleton." In addition, our wide-scale bioinformatics approach also discovered several previously unidentified genes and proteins associated with the ASD phenotype in BTBR mice, such as Caskin1, suggesting that bioinformatics could be an avenue by which novel therapeutic targets for ASD are uncovered. As a result, we believe that informed use of synergistic bioinformatics applications represents an invaluable tool for elucidating the etiology of complex disorders like ASD.