28 research outputs found
The On-orbit Calibrations for the Fermi Large Area Telescope
The Large Area Telescope (LAT) on--board the Fermi Gamma ray Space Telescope
began its on--orbit operations on June 23, 2008. Calibrations, defined in a
generic sense, correspond to synchronization of trigger signals, optimization
of delays for latching data, determination of detector thresholds, gains and
responses, evaluation of the perimeter of the South Atlantic Anomaly (SAA),
measurements of live time, of absolute time, and internal and spacecraft
boresight alignments. Here we describe on orbit calibration results obtained
using known astrophysical sources, galactic cosmic rays, and charge injection
into the front-end electronics of each detector. Instrument response functions
will be described in a separate publication. This paper demonstrates the
stability of calibrations and describes minor changes observed since launch.
These results have been used to calibrate the LAT datasets to be publicly
released in August 2009.Comment: 60 pages, 34 figures, submitted to Astroparticle Physic
Gold standard or fool's gold: the pursuit of certainty in experimental criminology
This article assesses some of the claims made for experimental research in the field of rehabilitation of offenders. It suggests that both policy officials and evaluators have tended to over-invest financially and intellectually in a technocratic model of reducing reoffending that emphasizes programmes for offenders, and to under-invest in models that see the process as a complex âpeople changingâ skill. It argues that the complexity of this process renders it hard to evaluate using experimental methods of evaluation such as randomized controlled trials (RCTs). RCTs provide strong internal validity, but in complex settings offer weak external validity, making it hard to generalize from the experimental setting to other settings. The article suggests that the proper role for evaluative research in this field should be seen as building and testing middle-level theories about how best to change offendersâ behaviour
Cohort Profile: the Born in Bradford multi-ethnic family cohort study
The Born in Bradford cohort study was established in 2007 to examine how genetic, nutritional, environmental, behavioural and social factors impact on health and development during childhood, and subsequently adult life in a deprived multi-ethnic population. Between 2007 and 2011, detailed information on socio-economic characteristics, ethnicity and family trees, lifestyle factors, environmental risk factors and physical and mental health has been collected from 12 453 women with 13 776 pregnancies (recruited at âŒ28 weeks) and 3448 of their partners. Mothers were weighed and measured at recruitment, and infants have had detailed anthropometric assessment at birth and post-natally up to 2 years of age. Results of an oral glucose tolerance test and lipid profiles were obtained on the mothers during pregnancy at âŒ28 weeks gestation, and pregnancy serum, plasma and urine samples have been stored. Cord blood samples have been obtained and stored and Deoxyribonucleic acid (DNA) extraction on 10 000 motherâoffspring pairs is nearly completed. The study has a biobank of over 250 000 samples of maternal blood, DNA and urine, cord blood and DNA and paternal saliva. Details of how scientists can access these data are provided in this cohort profile