60 research outputs found
Photometric redshifts for the Kilo-Degree Survey. Machine-learning analysis with artificial neural networks
We present a machine-learning photometric redshift analysis of the
Kilo-Degree Survey Data Release 3, using two neural-network based techniques:
ANNz2 and MLPQNA. Despite limited coverage of spectroscopic training sets,
these ML codes provide photo-zs of quality comparable to, if not better than,
those from the BPZ code, at least up to zphot<0.9 and r<23.5. At the bright end
of r<20, where very complete spectroscopic data overlapping with KiDS are
available, the performance of the ML photo-zs clearly surpasses that of BPZ,
currently the primary photo-z method for KiDS.
Using the Galaxy And Mass Assembly (GAMA) spectroscopic survey as
calibration, we furthermore study how photo-zs improve for bright sources when
photometric parameters additional to magnitudes are included in the photo-z
derivation, as well as when VIKING and WISE infrared bands are added. While the
fiducial four-band ugri setup gives a photo-z bias and scatter
at mean z = 0.23, combining magnitudes, colours, and galaxy
sizes reduces the scatter by ~7% and the bias by an order of magnitude. Once
the ugri and IR magnitudes are joined into 12-band photometry spanning up to 12
, the scatter decreases by more than 10% over the fiducial case. Finally,
using the 12 bands together with optical colours and linear sizes gives and .
This paper also serves as a reference for two public photo-z catalogues
accompanying KiDS DR3, both obtained using the ANNz2 code. The first one, of
general purpose, includes all the 39 million KiDS sources with four-band ugri
measurements in DR3. The second dataset, optimized for low-redshift studies
such as galaxy-galaxy lensing, is limited to r<20, and provides photo-zs of
much better quality than in the full-depth case thanks to incorporating optical
magnitudes, colours, and sizes in the GAMA-calibrated photo-z derivation.Comment: A&A, in press. Data available from the KiDS website
http://kids.strw.leidenuniv.nl/DR3/ml-photoz.php#annz
What influences national and foreign physiciansâ geographic distribution? An analysis of medical doctorsâ residence location in Portugal
Background
The debate over physiciansâ geographical distribution has attracted the attention of the
economic and public health literature over the last forty years. Nonetheless, it is still to date
unclear what influences physiciansâ location, and whether foreign physicians contribute to fill
the geographical gaps left by national doctors in any given country. The present research sets
out to investigate the current distribution of national and international physicians in Portugal, with the objective to understand its determinants and provide an evidence base for policymakers to identify policies to influence it.
Methods
A cross-sectional study of physicians currently registered in Portugal was conducted to describe the population and explore the association of physician residence patterns with relevant personal and municipality characteristics. Data from the Portuguese Medical Council
on physiciansâ residence and characteristics were analysed, as well as data from the National Institute of Statistics on municipalitiesâ population, living standards and health care network.
Descriptive statistics, chi-square tests, negative binomial and logistic regression modelling were applied to determine: (a) municipality characteristics predicting Portuguese and International physiciansâ geographical distribution, and; (b) doctorsâ characteristics that could
increase the odds of residing outside the countryâs metropolitan areas.
Results
There were 39,473 physicians in Portugal in 2008, 51.1% of whom male, and 40.2% between
41 and 55 years of age. They were predominantly Portuguese (90.5%), with Spanish,
Brazilian and African nationalities also represented. Population, Populationâs Purchasing
Power, Nurses per capita and Municipality Development Index (MDI) were the municipality
characteristics displaying the strongest association with national physiciansâ location. For
foreign physicians, the MDI was not statistically significant, while municipalitiesâ foreign
population applying for residence appeared to be an additional positive factor in their location
decisions. In general, being foreigner and male resulted to be the physician characteristics
increasing the odds of residing outside the metropolitan areas. However, among the
internationals, older doctors were more likely to reside outside metropolitan areas. Being
Spanish or Brazilian (but not of African origin) was found to increase the odds of being based
outside the Lisbon and Oporto metropolitan areas.
Conclusions
The present study showed the relevance of studying one countryâs physician population to
understand the factors driving national and international doctorsâ location decisions. A more
nuanced understanding of national and foreign doctorsâ location appears to be needed to
design more effective policies to reduce the imbalance of medical services across
geographical areas.The study was supported by a research grant from the Portuguese High Commission for Health to the International Health Department of the Institute of Hygiene and Tropical.
Medicine
Pharmacokinetics of imidocarb dipropionate in white-tailed deer (Odocoileus virginianus) after single intramuscular administration
This study was designed to investigate the pharmacokinetics of imidocarb, a carbanilide derivative, in white-tailed deer (Odocoileus virginianus). The pharmacokinetic properties of a single intramuscular (IM) dose of imidocarb were determined in 10 deer. A single IM injection of 3.0 mg/kg imidocarb dipropionate was administered, and blood samples were collected prior to, and up to 48 hr after imidocarb administration. Plasma imidocarb concentrations were determined by high-performance liquid chromatography with ultraviolet detection. The disposition of plasma imidocarb was best characterized by a two-compartment open model. The mean ± SE maximal imidocarb concentration in deer was 880.78 ± 81.12 ng/ml at 38.63 ± 5.30 min postinjection. The distribution phase had a half-life (t1/2α ) of 25.90 ± 10.21 min, and plasma imidocarb concentration declined with a terminal elimination half-life (t1/2ÎČ ) of 464.06 ± 104.08 min (7.73 ± 1.73 hr). Apparent volume of distribution based on the terminal phase (VZ /F) was 9.20 ± 2.70 L/kg, and apparent total body clearance (Cl/F) was 15.97 ± 1.28 ml min-1 kg-1
Pharmacokinetics of imidocarb dipropionate in white-tailed deer (Odocoileus virginianus) after single intramuscular administration
This study was designed to investigate the pharmacokinetics of imidocarb, a carbanilide derivative, in white-tailed deer (Odocoileus virginianus). The pharmacokinetic properties of a single intramuscular (IM) dose of imidocarb were determined in 10 deer. A single IM injection of 3.0 mg/kg imidocarb dipropionate was administered, and blood samples were collected prior to, and up to 48 hr after imidocarb administration. Plasma imidocarb concentrations were determined by high-performance liquid chromatography with ultraviolet detection. The disposition of plasma imidocarb was best characterized by a two-compartment open model. The mean ± SE maximal imidocarb concentration in deer was 880.78 ± 81.12 ng/ml at 38.63 ± 5.30 min postinjection. The distribution phase had a half-life (t1/2α ) of 25.90 ± 10.21 min, and plasma imidocarb concentration declined with a terminal elimination half-life (t1/2ÎČ ) of 464.06 ± 104.08 min (7.73 ± 1.73 hr). Apparent volume of distribution based on the terminal phase (VZ /F) was 9.20 ± 2.70 L/kg, and apparent total body clearance (Cl/F) was 15.97 ± 1.28 ml min-1 kg-1
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