Une Propriété Maximale de Matrices Binaires et Inversibles dont toutes les Lignes Contiennent le Même Nombre de Répétitions du Chiffre Un

AbstractA maximal property is obtained for binary nonsingular matrices in which each row has the same number of ones

Autoregression as a means of assessing the strength of seasonality in a time series

BACKGROUND: The study of the seasonal variation of disease is receiving increasing attention from health researchers. Available statistical tests for seasonality typically indicate the presence or absence of statistically significant seasonality but do not provide a meaningful measure of its strength. METHODS: We propose the coefficient of determination of the autoregressive regression model fitted to the data ([Image: see text]) as a measure for quantifying the strength of the seasonality. The performance of the proposed statistic is assessed through a simulation study and using two data sets known to demonstrate statistically significant seasonality: atrial fibrillation and asthma hospitalizations in Ontario, Canada. RESULTS: The simulation results showed the power of the [Image: see text] in adequately quantifying the strength of the seasonality of the simulated observations for all models. In the atrial fibrillation and asthma datasets, while the statistical tests such as Bartlett's Kolmogorov-Smirnov (BKS) and Fisher's Kappa support statistical evidence of seasonality for both, the [Image: see text] quantifies the strength of that seasonality. Corroborating the visual evidence that asthma is more conspicuously seasonal than atrial fibrillation, the calculated [Image: see text] for atrial fibrillation indicates a weak to moderate seasonality ([Image: see text] = 0.44, 0.28 and 0.45 for both genders, males and females respectively), whereas for asthma, it indicates a strong seasonality ([Image: see text] = 0.82, 0.78 and 0.82 for both genders, male and female respectively). CONCLUSIONS: For the purposes of health services research, evidence of the statistical presence of seasonality is insufficient to determine the etiologic, clinical and policy relevance of findings. Measurement of the strength of the seasonal effect, as can be determined using the [Image: see text] technique, is also important in order to provide a robust sense of seasonality

Sensitivity study of surface wind flow of a limited area model simulating the extratropical storm Delta affecting the Canary Islands

In November 2005 an extratropical storm named Delta affected the Canary Islands (Spain). The high sustained wind and intense gusts experienced caused significant damage. A numerical sensitivity study of Delta was conducted using the Weather Research & Forecasting Model (WRF-ARW). A total of 27 simulations were performed. Non-hydrostatic and hydrostatic experiments were designed taking into account physical parameterizations and geometrical factors (size and position of the outer domain, definition or not of nested grids, horizontal resolution and number of vertical levels). The Factor Separation Method was applied in order to identify the major model sensitivity parameters under this unusual meteorological situation. Results associated to percentage changes relatives to a control run simulation demonstrated that boundary layer and surface layer schemes, horizontal resolutions, hydrostaticity option and nesting grid activation were the model configuration parameters with the greatest impact on the 48 h maximum 10 m horizontal wind speed solution

Variation of the Chlorophyll a Related to Sea Surface Temperature, Wind and Geostrophic Currents in the Cape Verde Region Using Satellite Data

We present a comparative analysis of satellite derived climatologies in the Cape Verde region (CV). In order to establish chlorophyll a variability, in relation to other oceanographic phenomena, a set of, relatively long (from five to eight years), time series of chlorophyll a, sea surface temperature, wind and geostrophic currents, were ensembled for the Eastern Central Atlantic (ECA). We studied seasonal and inter-annual variability of phytoplankton concentration, in relation to the rest of the variables, with a special focus in CV. We compared the situation within the archipelago with those of the surrounding marine environments, such as the North West African Upwelling (NWAU), North Atlantic Subtropical Gyre (NASTG), North Equatorial Counter Current (NECC) and Guinea Dome (GD). At the seasonal scale, CV region behaves partly as the surrounding areas, nevertheless, some autochthonous features were also found. The maximum peak of the pigment having a positive correlation with temperature is found at the end of the year for all the points in the archipelago; a less remarkable rise with negative correlation is also detected in February for points CV2 and CV4. This is behavior that none of the surrounding environments have shown. This enrichment was found to be preceded by a drastic drop in wind intensity (SW Monsoon) during summer months. The inter-annual analysis shows a tendency for decreasing of the chlorophyll a concentration.Utilizando séries temporais (entre cinco e oito anos) de dados de satélite a grande escala para a zona de Cabo Verde (CV), faz-se uma análise da variabilidade da clorofila a relacionando-a com outros parâmetros oceanográficos como a temperatura superficial do mar, o vento e as correntes geostróficas. Estuda-se a variabilidade estacional e interanual da concentração do fitoplancton em relação ao resto das variáveis comparando a situação nas águas de Cabo Verde com o ambiente marinho à volta do arquipélago como o Upwelling Nordeste Africano (NWAU), o Giro Subtropical Norte-Atlântico (NASTG), a Contra Corrente Norte-Equatorial (NECC) e o Domo da Guiné (GD). À escala estacional, a zona de Cabo Verde comporta-se como parte das regiões envolventes, no entanto, algumas características autóctonas foram também encontradas. O pico máximo do pigmento mostrando uma correlação positiva com a temperatura foi encontrado no final do ano em todos os pontos eulerianos definidos para o arquipélago; um incremento menos notável, e com uma correlação negativa, também é detectada nos pontos CV2 e CV4. Este comportamento não foi visto em nenhum dos pontos do ambiente circundante ao arquipélago. O enriquecimento no final do ano foi precedido por um drástico decréscimo na intensidade do vento (Monsão do SW) durante os meses de verão. A análise interanual mostra uma tendência para o decréscimo da concentração da clorofila a

Higgs boson production via vector-like top-partner decays: diphoton or multilepton plus multijets channels at the LHC

We first build a minimal model of vector-like quarks where the dominant Higgs boson production process at LHC -- the gluon fusion -- can be significantly suppressed, being motivated by the recent stringent constraints from the search for direct Higgs production over a wide Higgs mass range. Within this model, compatible with the present experimental constraints on direct Higgs searches, we demonstrate that the Higgs ($h$) production via a heavy vector-like top-partner ($t_2$) decay, $pp \to t_2 \bar t_2$, $t_2\to t h$, allows to discover a Higgs boson at the LHC and measure its mass, through the decay channels $h\to \gamma\gamma$ or $h\to ZZ$. We also comment on the recent hint in LHC data from a possible $\sim 125$ GeV Higgs scalar, in the presence of heavy vector-like top quarks.Comment: 14 pages, 8 figure

Validation of a Scale to Measure Patient-Perceived Barriers to Medication Use

AIMS: Medication adherence may explain why patients show very different clinical outcomes. Previous assessments of adherence have used refill rates and pill counts. Few studies have investigated patient-identified barriers to using medications as prescribed. This is particularly true for persons with diabetes, most of whom are using poly-pharmacy regimens. We created a questionnaire to measure patient perceptions of barriers to medication adherence (PBMA) targeting a predominately low income, inner-city minority population. METHODS: Twenty items (Likert scale) leading with "I sometimes don't take my diabetes medicines because..." were developed from 5 focus groups (N=48). A questionnaire including these items was mailed to 1000 patients who have diabetes. RESULTS: Using data from 267 respondents (Mean age=58, 74%female, 43% non-Hispanic Caucasian, 77% income<$15,000), exploratory factor analyses with varimax rotation identified 5 factors, that may contribute to poor medication adherence: personal access to medications (F1); communication with providers (F2); understanding or appropriately following the prescribed regimen (F3); side effects (F4) and system factors that inhibited access to medication (F5). Cronbach alphas ranged from .73 to .83 for the five factors and was .92 for total scale score. No relationships were found between total scores and gender, race, or income. Greater perception of barriers was significantly (p<0.01) associated with being younger (r= -0.21), being bothered more by physical (r= -0.40) and emotional side effects (r= 0.43), and less satisfaction with control of blood sugar by diabetes medications (r= 0.45). CONCLUSIONS: This instrument is reliable, factorially valid, and consistent with clinical observation regarding factors known to be associated with patient medication adherence. Although study participants were patients with diabetes, the PBMA may be applicable to other therapeutic areas

Optimization of nickel and cobalt biosorption by native Serratia marcescens strains isolated from serpentine deposits using response surface methodology

The treatment of metal-polluted wastes is a challenging issue of environmental concern. Metals can be removed using microbial biomass, and this is an interesting approach towards the design of eco-friendly technologies for liquid waste treatment. The study reported here aimed to optimize nickel and cobalt biosorption from aqueous solutions using three native metal-resistant Serratia marcescens strains. Ni(II) and Co(II) biosorption by S. marcescens strains was found to fit better to Langmuir's model, with maximum uptake capacities of 13.5 mg g(-1) for Ni(II) ions and 19.9 mg g(-1) for Co(II) ions. Different experimental conditions of initial metal concentration, pH, initial biomass, and temperature were optimized using the Plackett-Burman method, and, finally, biomass and metal concentration were studied using the response surface methodology (RSM) to improve biosorption. The optimum uptake capacities for Co(II) ions by the three biosorbents used were obtained for initial metal concentrations of 35-40 mg L-1 and an initial biomass of 6 mg. For Ni(II) ions, the optimum uptake capacity was achieved with 1 mg of initial biomass for S. marcescens C-1 and C-19, and with 7 mg for S. marcescens C-16, with initial concentrations of 20-50 mg L-1. The results obtained demonstrate the viability of native S. marcescens strains as biosorbents for Ni(II) and Co(II) removal. This study also contributes to our understanding of the potential uses of serpentine microbial populations for the design of environmental cleanup technologies

Biosorption of nickel, cobalt, zinc and copper ions by Serratia marcescens strain 16 in mono and multimetallic systems

The metallurgical industry is one of the main sources of heavy metal pollution, which represents a severe threat to life. Metals can be removed from aqueous solutions by using microbial biomasses. This paper analyses the heavy metal biosorption capacity of Serratia marcescens strain 16 in single and multimetallic systems. The results obtained show that Co(II), Ni(II) and Zn(II) biosorption in monometallic systems is two to three times higher than in the presence of bi-metallic and multimetallic solutions. Fourier transform infrared spectroscopy confirmed that carbonyl, carboxyl and hydroxyl were the main functional groups, as well as the amide bands I and II involved in metal uptake, which are present in external structures of the bacterial cell. The results obtained demonstrated the viability of S. marcescens strain 16 as a biosorbent for the design of eco-friendly technologies for the treatment of waste liquor.The authors would like to acknowledge the financial support provided by the Iberoamerican PhD Program (UCA-UH), the AUIP and by the International Foundation of Science (Grant C/4078-2)

Deformation heterogeneity study of a 6061-T6 aluminum alloy processed by equal channel angular pressing

Among the severe plastic deformation techniques, the equal channel angular pressing (ECAP) has drastically improved the mechanical properties of the processed alloys. However, information regarding friction phenomenon, which modifies the deformation at the surface and the heterogeneity microstrain state produced by the process itself, is still scarce. In the present work, the deformation heterogeneity and the friction effect, at the surface in the bulk material of the 6061-T6 aluminum alloy processed by ECAP, is presented and discussed. The residual stress (RS) measurements were performed by means of X-Ray diffraction. By means of synchrotron diffraction, volumetric sections of the ECAPed samples were characterized. Finite element analysis showed a good agreement with the experimentally obtained residual stress and microhardness mapping results. The study also showed that the highest deformation zones were located at the outer parts of the deformed samples (top and bottom), while the inner zone showed strain oscillations of up to 49±2 MPa.Peer ReviewedPostprint (author's final draft