1,844 research outputs found

    Long memory and nonlinearities in realized volatility: a Markov switching approach.

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    Goal of this paper is to analyze and forecast realized volatility through nonlinear and highly persistent dynamics. In particular, we propose a model that simultaneously captures long memory and nonlinearities in which level and persistence shift through a Markov switching dynamics. We consider an efficient Markov chain Monte Carlo (MCMC) algorithm to estimate parameters, latent process and predictive densities. The insample results show that both long memory and nonlinearities are significant and improve the description of the data. The out-sample results at several forecast horizons, show that introducing these nonlinearities produces superior forecasts over those obtained from nested models.

    Potential implications of coronary artery calcium testing for guiding aspirin use among asymptomatic individuals with diabetes.

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    ObjectiveIt is unclear whether coronary artery calcium (CAC) is effective for risk stratifying patients with diabetes in whom treatment decisions are uncertain.Research design and methodsOf 44,052 asymptomatic individuals referred for CAC testing, we studied 2,384 individuals with diabetes. Subjects were followed for a mean of 5.6 ± 2.6 years for the end point of all-cause mortality.ResultsThere were 162 deaths (6.8%) in the population. CAC was a strong predictor of mortality across age-groups (age <50, 50-59, ≥60), sex, and risk factor burden (0 vs. ≥1 additional risk factor). In individuals without a clear indication for aspirin per current guidelines, CAC stratified risk, identifying patients above and below the 10% risk threshold of presumed aspirin benefit.ConclusionsCAC can help risk stratify individuals with diabetes and may aid in selection of patients who may benefit from therapies such as low-dose aspirin for primary prevention

    Terroir is a key driver of seed-associated microbial assemblages

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    Seeds have evolved in association with diverse microbial assemblages that may influence plant growth and health. However, little is known about the composition of seed-associated microbial assemblages and the ecological processes shaping their structures. In this work, we monitored the relative influence of the host genotypes and terroir on the structure of the seed microbiota through metabarcoding analysis of different microbial assemblages associated to five different bean cultivars harvested in two distinct farms. Overall, few bacterial and fungal operational taxonomic units (OTUs) were conserved across all seed samples. The lack of shared OTUs between samples is explained by a significant effect of the farm site on the structure of microbial assemblage, which explained 12.2% and 39.7% of variance in bacterial and fungal diversity across samples. This site-specific effect is reflected by the significant enrichment of 70 OTUs in Brittany and 88 OTUs in Luxembourg that lead to differences in co-occurrence patterns. In contrast, variance in microbial assemblage structure was not explained by host genotype. Altogether, these results suggest that seed-associated microbial assemblage is determined by niche-based processes and that the terroir is a key driver of these selective forces

    A prototype large-angle photon veto detector for the P326 experiment at CERN

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    The P326 experiment at the CERN SPS has been proposed with the purpose of measuring the branching ratio for the decay K^+ \to \pi^+ \nu \bar{\nu} to within 10%. The photon veto system must provide a rejection factor of 10^8 for \pi^0 decays. We have explored two designs for the large-angle veto detectors, one based on scintillating tiles and the other using scintillating fibers. We have constructed a prototype module based on the fiber solution and evaluated its performance using low-energy electron beams from the Frascati Beam-Test Facility. For comparison, we have also tested a tile prototype constructed for the CKM experiment, as well as lead-glass modules from the OPAL electromagnetic barrel calorimeter. We present results on the linearity, energy resolution, and time resolution obtained with the fiber prototype, and compare the detection efficiency for electrons obtained with all three instruments.Comment: 8 pages, 9 figures, 2 tables. Presented at the 2007 IEEE Nuclear Science Symposium, Honolulu HI, USA, 28 October - 3 November 200

    Effect of treatment of periodontitis on incretin axis in obese and non-obese individuals: A cohort study

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    CONTEXT: Periodontitis confers an increased risk of developing type 2 diabetes and, in patients with obesity, it might interfere with the incretin axis. The effect of periodontal treatment on glucoregulatory hormones remains unknown. OBJECTIVE: To evaluate the effect of periodontal treatment on incretin axis in obese and lean non-diabetic individuals. SETTING: King's College Dental Hospital and Institute, London, UK. PARTICIPANTS AND METHODS: The metabolic profile of obese and BMI-normal individuals affected by periodontitis was studied at baseline, 2 and 6 months after intensive periodontal treatment, by measuring plasma insulin, glucagon, GLP-1 and GIP and markers of systemic inflammation and oxidative stress. MAIN OUTCOME MEASURE(S): Circulating levels of incretins and inflammatory markers. RESULTS: At baseline, periodontal parameters were worse for obese than non-obese; this was accompanied by higher levels of circulating hs-CRP, insulin and GLP-1. The response to periodontal treatment was less favourable in the obese group, without significant variations of hs-CRP or malondialdehyde. Gluco-regulatory hormones changed differently after treatment: while insulin and glucagon did not vary at 2 and 6 months, GLP-1 and GIP significantly increased at 6 months in both groups. In particular, GLP-1 increased more rapidly in obese participants, while the increase of GIP followed similar trends across visits in both groups. CONCLUSIONS: Nonsurgical treatment of periodontitis is associated with increased GLP-1 and GIP levels in non-obese and obese patients; changes in GLP-1 were more rapid in obese participants. This might have positive implications for the metabolic risk of these individuals

    Drafting a prioritized checklist of Crop Wild Relatives and Wild Harvested Plants of Italy: problems and solutions

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    The National checklists of Crop Wild Relatives (CWR) and Wild Harvested Plants (WHP) are the basic tools for the development of in situ and ex situ conservation strategies of plant genetic resources. Here we discuss the methodologies and the prioritization process we previously used in the preparation of the prioritized checklist of CWR and WHP for Italy. The starting point were the most up-to-date Italian checklists of native and alien flora with their updates used as a nomenclatural and distributive source of data. Sardinia and Sicily were kept separate from peninsular Italy to perform detailed analyses focused on the taxa of the two major islands. The origin, the endemic status, cultivation, economic importance, uses, gene pool or taxon group, and the Red List status information were added. The WHP status was attributed to all the taxa with known direct uses. A qualitative approach was adopted in the prioritization process, the main criteria used were: 1) the inclusion of wild relative taxa of crops listed in Annex I of the International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGRFA) and/or by the Italian Institute of Statistics (ISTAT) for cultivated areas and yield in the last 5 years; 2) the threatened taxa occurring in national or global Red lists; 3) the endemism. This prioritization process generated 102 taxa as most in need of specific protection and /or monitoring measures, 57 taxa requiring monitoring because of their restricted distribution although not requiring specific protection measures and 735 taxa not requiring any specific protection. However, different prioritization processes could have been applied to the Italian checklists yielding different results. Here we discuss the matter

    Increased Rotatory Laxity after Anterolateral Ligament Lesion in Anterior Cruciate Ligament- (ACL-) Deficient Knees: A Cadaveric Study with Noninvasive Inertial Sensors

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    The anterolateral ligament (ALL) has been suggested as an important secondary knee restrain on the dynamic laxity in anterior cruciate ligament- (ACL-) deficient knees. Nevertheless, its kinematical contribution to the pivot-shift (PS) phenomenon has not been clearly and objectively defined, and noninvasive sensor technology could give a crucial contribution in this direction. The aim of the present study was to quantify in vitro the PS phenomenon in order to investigate the differences between an ACL-deficient knee and an ACL+ALL-deficient knee. Ten fresh-frozen paired human cadaveric knees (n=20) were included in this controlled laboratory study. Intact, ACL-deficient, and ACL+ALL-deficient knees were subjected to a manual PS test quantified by a noninvasive triaxial accelerometer (KiRA, OrthoKey). Kinematic data (i.e., posterior acceleration of the tibial lateral compartment) were recorded and compared among the three statuses. Pairwise Student's t-test was used to compare the single groups (p<0.05). Intact knees, ACL-deficient knees, and ACL+ALL-deficient knees showed an acceleration of 5.3±2.1 m/s2, 6.3±2.3 m/s2, and 7.8±2.1 m/s2, respectively. Combined sectioning of ACL and ALL resulted in a statistically significant acceleration increase compared to both the intact state (p<0.01) and the ACL-deficient state (p<0.01). The acceleration increase determined by isolated ACL resection compared to the intact state was not statistically significant (p>0.05). The ALL sectioning increased the rotatory laxity during the PS after ACL sectioning as measured through a user-friendly, noninvasive triaxial accelerometer

    Mapping assessments instruments for headache disorders against the icf biopsychosocial model of health and disability

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    Headache disorders have a strong impact on sufferers’ lives. However, the “content” of assessment instruments addressing concepts, such as disability and quality of life (QoL), has not comprehensively been addressed. We searched SCOPUS for research papers in which outcome measures were used in adult populations of patients with migraine, tension-type headache (TTH), and cluster headache (CH). The content of single instruments was then mapped against the International Classification of Functioning, Disability, and Health. A total of 150 papers and 26 instruments were included: 15 addressed disability or impact, two addressed work-related difficulties, and nine addressed QoL. Few instruments were commonly used across the conditions and covered domains of functioning were impact on daily life activities, homework, school, and work-related tasks, leisure time, informal and family relations, pain, emotional difficulties, energy level, and impulse control. Most of the research is based on instruments that were developed for migraine, which is critical for CH, and the impact of headache disorders on work-related activities is poorly acknowledged. Further research is needed to expand the scope of headaches impact on daily life activities, and on environmental factors relevant to headache disorders to raise knowledge on the less represented areas, e.g., TTH impact

    Avaliação dos gêneros de orquídeas encontrados nos fragmentos do Parque Natural Municipal Fazenda Santa Cecilia do Ingá, médio vale do Rio Paraíba do Sul

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    Entre os períodos de outubro de 2008 a dezembro de 2009, foi realizado o Projeto “Avaliação dos gêneros de orquídeas encontrados em fragmentos de Floresta Atlântica, sobre pressão antrópica, na região do médio vale do Rio Paraíba do Sul”. Nesse período foram realizadas 3 etapas, das quais a primeira etapa foi o levantamento bibliográfico sobre a família orchidaceae em áreas de Mata Atlântica. Na segunda etapa, foi realizado um levantamento visual e fotográfico objetivando identificar, ao nível de gêneros, as orquídeas presentes no Parque Natural Municipal Fazenda Santa Cecília do Ingá, coordenadas latitude 22°31'23" S e longitude 44°06'15" na região do médio vale do Rio Paraíba do Sul em Volta Redonda – RJ, definida como área de estudo. Com o auxílio de um GPS foram realizadas 6 incursões exploratórias, de março a setembro de 2009, percorrendo trechos no interior da mata em busca de possíveis gêneros de orquídeas ocorrentes na mesma. Foram localizadas 4 espécies de orquídeas, pertencentes aos generos: Catasetum, Oceoclades, Pollystachia e Rodriguesia. Os locais de ocorrência foram georeferenciados e plotados em mapa. Juntamente com as observações visuais foram coletados os parâmetros ambientais temperatura e umidade relativa do ar. O gênero mais abundante foi Oceoclades, o qual teve ocorrência registrada em todas as 6 incursões realizadas na Unidade de Conservação (UC). A exceção do Catasetum, encontrado em uma das encostas e curiosamente no viveiro florestal de unidade, os demais gêneros, Rodriguesia e Pollystachia, apresentou ocorrência restrita em uma pequena área, com umidade relativa do ar superior as demais. Os parâmetros ambientais coletados apresentaram no interior da mata, umidade relativa do ar atingindo 91%, acompanhada de temperatura de 26ºC. Entretanto, comparados a área urbana, uma grande variação foi observada, com a umidade relativa do ar chegando a 45% e a temperatura a 33°C cerca de 30 minutos após os dados anteriores terem sido coletados no interior da floresta. Buscando delimitar padrões que expliquem a distribuição e a ocorrência das espécies encontradas, acredita-se que estas espécies sobreviveram às profundas mudanças ocorridas no uso e ocupação do solo no passado, estando presentes em fragmentos florestais vizinhos aos da área de estudo, de relevo mais acidentado e pouco interessante para a agricultura. Ao passo que a área de estudo, segundo registros históricos, foi totalmente desmatada no século XIX devido à atividade cafeicultora. Dado esse que pode ser evidenciado em campo, devido às características de floresta jovem observados na área de estudo. Com o passar dos anos os processos de dispersão estariam pouco a pouco promovendo o repovoamento dos fragmentos florestais em processo de sucessão, com condições bióticas e abióticas para abrigar representantes dos gêneros citados. Por outro lado, levando-se em consideração o número de gêneros de orquídeas encontrados em fragmentos mais preservados deste ecossistema, podemos classificar os fragmentos em tela como de baixa diversidade, apontando para necessidade de implantação de corredores ecológicos que facilitem a regeneração e a sucessão vegetal, corroborando para o incremento do intercâmbio genético, favorecendo a fauna, flora e os processos e serviços ambientais inerentes a estas regiões
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