Search results for "statistical"
showing 10 items of 4960 documents
CloudSim: A fair benchmark for comparison of methods for times series reconstruction from cloud and atmospheric contamination
2015
Cloud contamination of optical data is a constant and annoying feature of time series analyses, whether while using vegetation indices or surface temperatures, since it tends to decrease artificially the values taken by these parameters. Therefore, any time series analysis of optical data needs a previous step for gap-filling reconstruction of the time series. Numerous techniques have been presented in the literature to carry out this preliminary and mandatory step. However, the evaluation and comparison of these techniques is difficult, since no “truth” time series is available. We present here a probabilistic model (CloudSim) to provide global typical annual time series for NDVI (Normaliz…
Empreintes et pistes de rhinocerotidae (Mammalia, Perissodactyla) du gisement pliocène terminal de Laetoli (Tanzanie)
1993
Resume Les traces (empreintes et pistes) des rhinoceros actuels sont tres mal connues, et une seule empreinte fossile de rhinoceros neogene ou quaternaire a ete decrite a ce jour. A Laetoli 7 sites ont livre des traces de rhinoceros, toutes attribuables au nouvel ichnogenre Dicerotinichnus; les traces des sites H, I et J ne sont pas definissables specifiquement. Les traces des sites A et N (deux pistes dont une a 26 couples d'empreintes et une a 5 couples dont certains de tres bonne qualite) permettent de definir le nouvel ichnobinome Dicerotinichnus laetoliensis nov. sp. attribue a Ceratotherium praecox. Les traces des sites M West et M East (deux pistes a 4 et 8 couples d'empreintes et 4 …
Nautiles paléocènes du Niger
2001
Resume De nombreux nautiles tertiaires ont ete recoltes au Niger tant dans le Nord-Ouest du pays (region de Mentes et Tillia) que dans le centre (region de Kao) et, dans le Sud, aux environs de Malbaza. Leur etude montre deux faunes assez differentes, la plus riche, dans la region centrale (Kao), caracterisee par de nombreux specimens de Deltoidonautilus molli, la seconde, plus pauvre, caracterisee par Deltoidonautilus sudanensis et D. chudeaui aussi bien au Nord qu'au Sud. Malgre des differences considerables, ces formes qui peuvent etre attribuees au Paleocene, ne semblent pas, d'apres les fossiles associes (notamment l'echinide Linthia sudanensis sudanensis), indiquer une difference d'âg…
Stochastic dynamical modelling of spot freight rates
2014
Based on empirical analysis of the Capesize and Panamax indices, we propose different continuous-time stochastic processes to model their dynamics. The models go beyond the standard geometric Brownian motion, and incorporate observed effects like heavy-tailed returns, stochastic volatility and memory. In particular, we suggest stochastic dynamics based on exponential Levy processes with normal inverse Gaussian distributed logarithmic returns. The Barndorff-Nielsen and Shephard stochastic volatility model is shown to capture time-varying volatility in the data. Finally, continuous-time autoregressive processes provide a class of models sufficiently rich to incorporate short-term persistence …
Structure function as a tool in AE and Dst time series analysis
1995
A new method to analyse the structure function (SF) has been constructed and used in the analysis of the AE time series for the years 1978-85 and Dst time series for 1957-84. It is shown that this SF analysis makes a clear distinction between affine and periodicity dominated time series, and it displays the essential periodicities of the series in a range relevant to its characteristic time scale. The AE time series is found to be affine such that the scaling exponent changes at a time scale of 113 (±9) minutes. On the other hand, in the SF function analysis, the Dst data are dominated by the 24-hour and 27-day periods. The 27-day period is modulated by the annual variation.
Occupational stress among Brazilian oral-maxillofacial surgeons
2009
Purpose: The aim of the present study was to assess the stress level of oral-maxillofacial surgeons, based on the Demand-Control Model. Methods: A cross-sectional study was carried out with 128 oral-maxillofacial surgeons who participated in the Brazilian Congress of Oral-Maxillofacial Surgery held in the city of Florianópolis, State of Santa Catarina, Brazil. Data was obtained using a questionnaire that incorporated the Demand-Control Model (Job Content Questionnaire), which evaluates psychosocial experiences at work. Information on age, gender and professional qualification was also collected. The data was displayed in contingency tables. The following statistical tests were used with a 5…
Happy Aged People Are All Alike, While Every Unhappy Aged Person Is Unhappy in Its Own Way
2011
Aging of the world’s population represents one of the most remarkable success stories of medicine and of humankind, but it is also a source of various challenges. The aim of the collaborative cross-cultural European study of adult well being (ESAW) is to frame the concept of aging successfully within a causal model that embraces physical health and functional status, cognitive efficacy, material security, social support resources, and life activity. Within the framework of this project, we show here that the degree of heterogeneity among people who view aging in a positive light is significantly lower than the degree of heterogeneity of those who hold a negative perception of aging. We base…
Measurement of the will to live in older adults: Transcultural adaptation, validity and reliability of the Will-to-Live Scale
2019
Abstract Objective The Will-to-Live Scale (WTLS) is used to measure the will to live in older adults; however, there is no Spanish version. The objective of the study was to translate the WTLS into Spanish, assess its internal structure, reliability, and the correlates between WTLS and life satisfaction, resilience, and depression in older Peruvian adults. Method The participants were 235 Peruvian older adults (M = 72.69, SD = 6.68), evaluated between March to May 2019, selected through non-probability sampling. The WTLS, the Satisfaction with Life Scale (SWLS), the Brief Resilient Coping Scale (BRCS) and the Patient Health Questionnaire-2 (PHQ-2) were administered. Data analysis included r…
Impact of oral health on nutritional status, self-perception of oral health and quality of life of institutionalized elderly
2021
Background This study aimed to investigate the influence of oral health on nutritional status, self-perception of oral health and health related quality of life of institutionalized elders. Material and methods A cross-sectional study was conducted with 193 institutionalized elders living in the metropolitan region of Joao Pessoa (Brazil). The independent variables included were: 1) caries experience (DMFT index and its components); 2) use and need of dental prostheses; and 3) type of edentulism. The dependent variables included were related to nutritional status, self-perception of oral health and health-related quality of life. Data were submitted to a descriptive and comparative analysis…
How we compensate for memory loss in old age: adapting and validating the Memory Compensation Questionnaire (MCQ) for Spanish populations.
2012
Compensating entails using external strategies and mechanisms that help overcome or alleviate the decreasing memory function that comes with age. This study aims to adapt and validate the MCQ in the elderly Spanish population. A total of 403 elderly people aged between 65 and 92 in the city of Valencia (Spain) completed the questionnaire for the validation process. The factorial validity of the scale was tested using confirmatory factor analysis. The result showed a first order five-factor model with 23 items that met the criteria for model fit according to multiple fit indices. As a general conclusion, the adaptation into Spanish provided a reliable and valid measure of compensation in the…