Optimal PSF modeling for weak lensing: complexity and sparsity

We investigate the impact of point spread function (PSF) fitting errors on cosmic shear measurements using the concepts of complexity and sparsity. Complexity, introduced in a previous paper, characterizes the number of degrees of freedom of the PSF. For instance, fitting an underlying PSF with a model with low complexity will lead to small statistical errors on the model parameters, however these parameters could suffer from large biases. Alternatively, fitting with a large number of parameters will tend to reduce biases at the expense of statistical errors. We perform an optimisation of scatters and biases by studying the mean squared error of a PSF model. We also characterize a model sparsity, which describes how efficiently the model is able to represent the underlying PSF using a limited number of free parameters. We present the general case and illustrate it for a realistic example of PSF fitted with shapelet basis sets. We derive the relation between complexity and sparsity of the PSF model, signal-to-noise ratio of stars and systematic errors on cosmological parameters. With the constraint of maintaining the systematics below the statistical uncertainties, this lead to a relation between the required number of stars to calibrate the PSF and the sparsity. We discuss the impact of our results for current and future cosmic shear surveys. In the typical case where the biases can be represented as a power law of the complexity, we show that current weak lensing surveys can calibrate the PSF with few stars, while future surveys will require hard constraints on the sparsity in order to calibrate the PSF with 50 stars.Comment: accepted by A&A, 9 pages, 6 figure

Cosmic Shear Systematics: Software-Hardware Balance

Cosmic shear measurements rely on our ability to measure and correct the Point Spread Function (PSF) of the observations. This PSF is measured using stars in the field, which give a noisy measure at random points in the field. Using Wiener filtering, we show how errors in this PSF correction process propagate into shear power spectrum errors. This allows us to test future space-based missions, such as Euclid or JDEM, thereby allowing us to set clear engineering specifications on PSF variability. For ground-based surveys, where the variability of the PSF is dominated by the environment, we briefly discuss how our approach can also be used to study the potential of mitigation techniques such as correlating galaxy shapes in different exposures. To illustrate our approach we show that for a Euclid-like survey to be statistics limited, an initial pre-correction PSF ellipticity power spectrum, with a power-law slope of -3 must have an amplitude at l =1000 of less than 2 x 10^{-13}. This is 1500 times smaller than the typical lensing signal at this scale. We also find that the power spectrum of PSF size \dR^2) at this scale must be below 2 x 10^{-12}. Public code available as part of iCosmo at http://www.icosmo.orgComment: 5 pages, 3 figures. Submitted to MNRA

Information Gains from Cosmological Probes

In light of the growing number of cosmological observations, it is important to develop versatile tools to quantify the constraining power and consistency of cosmological probes. Originally motivated from information theory, we use the relative entropy to compute the information gained by Bayesian updates in units of bits. This measure quantifies both the improvement in precision and the 'surprise', i.e. the tension arising from shifts in central values. Our starting point is a WMAP9 prior which we update with observations of the distance ladder, supernovae (SNe), baryon acoustic oscillations (BAO), and weak lensing as well as the 2015 Planck release. We consider the parameters of the flat $\Lambda$CDM concordance model and some of its extensions which include curvature and Dark Energy equation of state parameter $w$. We find that, relative to WMAP9 and within these model spaces, the probes that have provided the greatest gains are Planck (10 bits), followed by BAO surveys (5.1 bits) and SNe experiments (3.1 bits). The other cosmological probes, including weak lensing (1.7 bits) and {$\rm H_0$} measures (1.7 bits), have contributed information but at a lower level. Furthermore, we do not find any significant surprise when updating the constraints of WMAP9 with any of the other experiments, meaning that they are consistent with WMAP9. However, when we choose Planck15 as the prior, we find that, accounting for the full multi-dimensionality of the parameter space, the weak lensing measurements of CFHTLenS produce a large surprise of 4.4 bits which is statistically significant at the 8 $\sigma$ level. We discuss how the relative entropy provides a versatile and robust framework to compare cosmological probes in the context of current and future surveys.Comment: 26 pages, 5 figure

Optimized Principal Component Analysis on Coronagraphic Images of the Fomalhaut System

We present the results of a study to optimize the principal component analysis (PCA) algorithm for planet detection, a new algorithm complementing ADI and LOCI for increasing the contrast achievable next to a bright star. The stellar PSF is constructed by removing linear combinations of principal components, allowing the flux from an extrasolar planet to shine through. The number of principal components used determines how well the stellar PSF is globally modelled. Using more principal components may decrease the number of speckles in the final image, but also increases the background noise. We apply PCA to Fomalhaut VLT NaCo images acquired at 4.05 micron with an apodized phase plate. We do not detect any companions, with a model dependent upper mass limit of 13-18 M_Jup from 4-10 AU. PCA achieves greater sensitivity than the LOCI algorithm for the Fomalhaut coronagraphic data by up to 1 magnitude. We make several adaptations to the PCA code and determine which of these prove the most effective at maximizing the signal-to-noise from a planet very close to its parent star. We demonstrate that optimizing the number of principal components used in PCA proves most effective for pulling out a planet signal.Comment: Accepted for publication in ApJ, 7 pages, 9 figure

Proposta de Sistema de Gestão da Qualidade no Centro Social de Quadrazais

O presente relatório de estágio profissionalizante terá como objetivo apresentar uma proposta de um Sistema de Gestão de Qualidade (SGQ) para o Centro Social de Quadrazais (CSQ), no Concelho do Sabugal. O CSQ é uma Entidade do Setor Não Lucrativo (ESNL) que dinamiza duas respostas sociais, especificamente: Estrutura Residencial para Pessoas Idosas (ERPI) e o Serviço de Apoio Domiciliário (SAD). Assim, o planeamento de um SGQ melhora o desempenho da CSQ, aumenta o grau de satisfação das partes interessadas (utentes, familiares, profissionais, voluntários, entidades parceiras e financiadoras, entre outras), gera maior economia, eficácia e eficiência dos processos e contribui para que o CSQ utilize a qualidade dos seus serviços como uma fonte de vantagem competitiva no Terceiro Sector. Para tal, deve estabelecer-se a política e os objetivos da qualidade para promover uma estratégia de sustentabilidade através do conceito da sua melhoria. Para a realização do estágio profissionalizante propõe-se como metodologia de investigação para a análise teórica, a revisão de literatura científica e dos normativos legais para contextualizar a temática da qualidade, em geral, e do SGG, com particular ênfase na Norma NP EN ISO 9001: 2015 (IPQ, 2015b) – SGQ: Requisitos. Para a concretização da análise empírica, recorreu-se ao método do caso de estudo por o mesmo implicar um conhecimento profundo da realidade a investigar (Yin, 2009). Os resultados evidenciam a fase de planeamento do SGQ, suportado na Norma NP EN ISO 9001: 2015 (IPQ, 2015b), no CSQ, onde se adota o processo de melhoria contínua e fomenta a deteção de não conformidades e oportunidades de melhoria que garantam a participação das partes interessadas. Assim, a liderança e o desenvolvimento de parcerias entre o IPG, a UPM, o CSQ e a unidade de missão do Sabugal Mais Social permitiram que fosse assegurada a elaboração desta proposta de relatório de estágio profissionalizante, baseada na dinâmica do CSQ que surge, cada vez mais, com a preocupação de um serviço de excelência e um aprimoramento nas práticas de responsabilidade social destas entidades direcionadas para o envelhecimento ativo e saudável

The Association Between Neurocognitive Impairment and Health-Related Quality of Life Among People Living with Human Immunodeficiency Virus (HIV).

Background: Despite the use of combination antiretroviral therapy, HIV associated neurocognitive impairment (NCI) persists in HIV seropositive persons, albeit in milder forms than before therapy was available. Nevertheless, the relationship between NCI and health-related quality of life (HRQoL) is not well known. Method: Baseline data from the CHARTER study was used to investigate the association between NCI and HRQoL. Factor analysis was employed to summarize the 35-item Medical Outcome Survey questionnaire into physical and mental HRQoL scores. General linear models were employed to investigate the association between NCI, as measured by global deficit scores (GDS), and HRQoL, and to control for confounding. Results: A total of 1,340 HIV participants were analyzed, including 35.6% NCI, 77.2% males, 70.5% unemployed, and 42.2% depressed. The mean (standard deviation) mental HRQoL scores (lower scores are worse) for impaired and unimpaired participants were 64.0 (18.4) and 67.9 (18.6) and mean physical HRQoL scores for impaired and unimpaired participants were 60.3 (24.7) and 65.1 (25.9), respectively. There was an inverse association between NCI and mental HRQoL in unadjusted [-4.38 (-6.70 to -2.06)] and adjusted analysis [-2.56 (-4.83 to -0.30)], controlling for unemployment and current psychotropic medication use. The association between NCI and physical HRQoL was significant in the unadjusted analysis [-4.62 (-7.45 to -1.78)] but not in the adjusted analysis [2.20 (-4.81 to 0.40)], controlling for unemployment, CD4 nadir, and positive opiate test results and other covariates. Conclusion. The inverse association between NCI and HRQoL was confounded mainly by employment and mediated by depression. Interventions aimed at the comprehensive treatment of HIV patients should include the management of depression and maintenance of employment

Comparison between phenotype and molecular resistance characteristic in Staphylococcus epidermidis isolates from wound infections in Al-Basrah province, Iraq

Background:Staphylococcus epidermidis is considered the upper respiratory tract's human skin flora and mucosal membrane and displays low pathogenic capacity in healthy individuals. Drug-resistant strains can be identified as a natural result of the microflora through antibiotic therapy and are a possible cause of pathogenic strain resistance genes. Methods:Culture, biochemical analysis and Vitek®2 Utilizing for identified the One hundred and fifty swab sample was collected from different wounds infected. S. epidermidis strain's ability to resist antibiotics was tested using a disk diffusion method. Result of antibiotic sensitivity test was confirmed and supported by Vitek®2 system. Also, the PCR antibiotic resistance gene was detected. Results: Out of 150 swab samples, twelve were positive for S. epidermidis.. Disc method was shown the 75%,66.7%,83.3% and 58.3% harboured highest prevalence of antimicrobial resistance against penicillin, oxacillin, cefoxitin and erythromycin respectively.While the moderate prevalence 50.7%,41.7% and 33.3% of resistance against tetracycline,clandomycin and ciprofloxacin respectively. Furthermore, lowest incidence was shown the 25% for both of resistance against rifampin, and gentamycin. The Vitek®2 system was confirmed and support antibiotic sensitivity test. A most frequently found antibiotic resistance genes amongst S. epidermidis strains, according to the findings, were mecA (91.7%), blaZ (91.7) , ermA (16.7%),ermB (25%),ermC (25%), tetM (25%), tetK (33.3 %) and aacA-aphD (41.7%) respectively. All S. epidermidis strain doesn't have ,vanA and vanB antibiotic resistance gene. Conclusion:Frequency of resistance to antibiotic should be detected more than one method , and used the Vitek®2 system detected the antibiotic resistance gave better support for result. Additional PCR technique, actually very important to detect antibiotic resistance genes of S. epidermidis strains