Shedding Light on the Galaxy Luminosity Function

From as early as the 1930s, astronomers have tried to quantify the statistical nature of the evolution and large-scale structure of galaxies by studying their luminosity distribution as a function of redshift - known as the galaxy luminosity function (LF). Accurately constructing the LF remains a popular and yet tricky pursuit in modern observational cosmology where the presence of observational selection effects due to e.g. detection thresholds in apparent magnitude, colour, surface brightness or some combination thereof can render any given galaxy survey incomplete and thus introduce bias into the LF. Over the last seventy years there have been numerous sophisticated statistical approaches devised to tackle these issues; all have advantages -- but not one is perfect. This review takes a broad historical look at the key statistical tools that have been developed over this period, discussing their relative merits and highlighting any significant extensions and modifications. In addition, the more generalised methods that have emerged within the last few years are examined. These methods propose a more rigorous statistical framework within which to determine the LF compared to some of the more traditional methods. I also look at how photometric redshift estimations are being incorporated into the LF methodology as well as considering the construction of bivariate LFs. Finally, I review the ongoing development of completeness estimators which test some of the fundamental assumptions going into LF estimators and can be powerful probes of any residual systematic effects inherent magnitude-redshift data.Comment: 95 pages, 23 figures, 3 tables. Now published in The Astronomy & Astrophysics Review. This version: bring in line with A&AR format requirements, also minor typo corrections made, additional citations and higher rez images adde

Sintomatologia de depressão autorreferida por idosos que vivem em comunidade The symptomatology of self-referred depression by elderly people who live in a shantytown

Este estudo exploratório quantitativo objetivou avaliar a sintomatologia da depressão autorreferida por idosos, considerando variáveis sociodemográficas. Os dados coletados por meio de entrevista semiestruturada e da Escala de Depressão Geriátrica Abreviada envolvendo 240 idosos residentes em João Pessoa (PB), no período de outubro a dezembro de 2010, foram analisados pelos softwares Excel e SPSS. Verificou-se que 75,8% não apresentaram grau de sintomatologia de depressão e 24,2% manifestaram depressão leve ou severa. De acordo com essas varáveis, nesses idosos com grau depressivo verificou-se que: em relação à faixa etária, aqueles com grau depressivo leve e severo destacam maior frequência entre 71 a 76 anos, 31,0%; com relação ao gênero, o feminino destaca-se com 86,0%; sobre o estado civil, os casados com 41,3% e os viúvos com 34,5%; considerando-se a renda familiar, os de 01 até 03 salários mínimos, 50%, apresentaram grau leve; com vistas à escolaridade, dos que não evidenciaram grau de depressão, 84,6%, sabem ler e escrever. Portanto, pode afirmar-se que a sintomatologia da depressão em idosos apresenta relação com as condições socioeconômicas e culturais, fortalecendo a necessidade de políticas públicas de saúde que garantam um atendimento integral e de qualidade, considerando essas variáveis.<br>The scope of this quantitative exploratory study was to evaluate the symptomatology of self-referred depression by the elderly, taking socio-demographic variables into consideration. The data collected by means of semi-structured interviews and the Abbreviated Geriatric Depression Scale involving 240 elderly residents in João Pessoa in the state of Paraíba between October and December 2010 were analyzed by Excel and SPSS software. It was found that 75.8 % had no degree of symptomatology of depression, and 24.2 % manifested mild or severe depression. According to these variables, in the elderly patients with depression it was found that: in relation to age, the elderly with mild and severe depression appear more frequently between 71 to 76 years - 31%; in relation to gender, females stand out with 86%; on marital state, married couples with 41.3 %, and widowers with 34.5 %; considering family income, from 1 up to 3 minimum wages, 50 %, revealed mild incidence; with respect to schooling, elderly people who have no depression, 84.6 %, can read and write. Therefore, it can be said that the symptomatology of depression in the elderly is related to socio-economic and cultural conditions, emphasizing the need for public health policies that ensure comprehensive care and quality considering these variables