5,526 research outputs found
Supporting Fathers in Multi-Ethnic Societies: Insights from British Asian Fathers
AbstractThere is concern that current UK policy and intervention aimed at supporting fathers remains primarily informed by dominant White middle-class values and experiences, and therefore fails to respond adequately to the needs of Britain's diverse fathers. This paper contributes to understanding of ethnic diversity in fathering contexts, practices and experiences, by reporting findings from a qualitative study of British Asian fathers, involving in-depth interviews with fifty-nine fathers and thirty-three mothers from Bangladeshi Muslim, Pakistani Muslim, Gujarati Hindu and Punjabi Sikh background, and over eight additional respondents engaged through Key Informant interviews, ethnographic interviews and group discussions. The paper highlights four areas that require greater recognition by policy-makers and practitioners to appropriately meet the needs of fathers from diverse ethnic and socio-economic backgrounds. These are: recognising that fathers and mothers do not necessarily constitute an autonomous unit; appreciating diversity in fathers’ understandings of desirable child outcomes; addressing additional obstacles to achieving similar outcomes for children; and understanding that the boundaries and content of fathering are not universally recognised. Policies that are less normative and more responsive to diversity are essential to ensure that all fathers can be effectively supported.</jats:p
Analytical Solutions to the Mass-Anisotropy Degeneracy with Higher Order Jeans Analysis: A General Method
The Jeans analysis is often used to infer the total density of a system by
relating the velocity moments of an observable tracer population to the
underlying gravitational potential. This technique has recently been applied in
the search for Dark Matter in objects such as dwarf spheroidal galaxies where
the presence of Dark Matter is inferred via stellar velocities. A precise
account of the density is needed to constrain the expected gamma ray flux from
DM self-annihilation and to distinguish between cold and warm dark matter
models. Unfortunately the traditional method of fitting the second order Jeans
equation to the tracer dispersion suffers from an unbreakable degeneracy of
solutions due to the unknown velocity anisotropy of the projected system. To
tackle this degeneracy one can appeal to higher moments of the Jeans equation.
By introducing an analog to the Binney anisotropy parameter at fourth order,
beta' we create a framework that encompasses all solutions to the fourth order
Jeans equations rather than those in the literature that impose unnecessary
correlations between anisotropy of second and fourth order moments. The
condition beta' = f(beta) ensures that the degeneracy is lifted and we
interpret the separable augmented density system as the order-independent case
beta'= beta. For a generic choice of beta' we present the line of sight
projection of the fourth moment and how it could be incorporated into a joint
likelihood analysis of the dispersion and kurtosis. Having presented the
mathematical framework, we then use it to develop a statistical method for the
purpose of placing constraints on dark matter density parameters from discrete
velocity data. The method is tested on simulated dwarf spheroidal data sets
leading to results which motivate study of real dwarf spheroidal data sets.Comment: 21 pages, 15 figures. Accepted by MNRAS. Typo corrected in eq. 3
Increasing peptide identifications and decreasing search times for ETD spectra by pre-processing and calculation of parent precursor charge
<p>Abstract</p> <p>Background</p> <p>Electron Transfer Dissociation [ETD] can dissociate multiply charged precursor polypeptides, providing extensive peptide backbone cleavage. ETD spectra contain charge reduced precursor peaks, usually of high intensity, and whose pattern is dependent on its parent precursor charge. These charge reduced precursor peaks and associated neutral loss peaks should be removed before these spectra are searched for peptide identifications. ETD spectra can also contain ion-types other than c and z<b>˙</b>. Modifying search strategies to accommodate these ion-types may aid in increased peptide identifications. Additionally, if the precursor mass is measured using a lower resolution instrument such as a linear ion trap, the charge of the precursor is often not known, reducing sensitivity and increasing search times. We implemented algorithms to remove these precursor peaks, accommodate new ion-types in noise filtering routine in OMSSA and to estimate any unknown precursor charge, using Linear Discriminant Analysis [LDA].</p> <p>Results</p> <p>Spectral pre-processing to remove precursor peaks and their associated neutral losses prior to protein sequence library searches resulted in a 9.8% increase in peptide identifications at a 1% False Discovery Rate [FDR] compared to previous OMSSA filter. Modifications to the OMSSA noise filter to accommodate various ion-types resulted in a further 4.2% increase in peptide identifications at 1% FDR. Moreover, ETD spectra when searched with charge states obtained from the precursor charge determination algorithm is shown to be up to 3.5 times faster than the general range search method, with a minor 3.8% increase in sensitivity.</p> <p>Conclusion</p> <p>Overall, there is an 18.8% increase in peptide identifications at 1% FDR by incorporating the new precursor filter, noise filter and by using the charge determination algorithm, when compared to previous versions of OMSSA.</p
International Wildlife Law : Understanding and Enhancing Its Role in Conservation
We gratefully acknowledge valuable input by Kees Bastmeijer, Sanja Bogojevic, Jennifer Dubrulle, and Han Somsen.Peer reviewedPublisher PD
Measuring transverse velocities in gravitationally lensed extragalactic systems using an annual parallax effect
A parallax method to determine transverse velocity in a gravitationally
lensed system is described. Using the annual motion of the Earth around the Sun
allows us to probe the local structure of the magnification map that, under
certain assumptions, can be used to infer the effective transverse velocity.
The method is applied to OGLE data for QSO2237+0305 and the velocity value is
estimated to be about (15 +/- 10) km/s if attributed to the lensing galaxy or
about (420 +/- 300) km/s if attributed to the quasar. We find this estimate
unreasonably small and conclude that we have not measured a parallax effect. We
give a short list of properties that a system should possess to allow a
successful implementation of this method.Comment: v2: journal reference update
Virial Sequences for Thick Discs and Haloes: Flattening and Global Anisotropy
The virial theorem prescribes the ratio of the globally-averaged equatorial
to vertical velocity dispersion of a tracer population in spherical and
flattened dark haloes. This gives sequences of physical models in the plane of
global anisotropy and flattening. The tracer may have any density, though there
are particularly simple results for power-laws and exponentials. We prove the
flattening theorem: for a spheroidally stratified tracer density with axis
ratio q in a dark density potential with axis ratio g, the ratio of globally
averaged equatorial to vertical velocity dispersion depends only on q/g. As the
stellar halo density and velocity dispersion of the Milky Way are accessible to
observations, this provides a new method for measuring the flattening of the
dark matter. If the kinematics of the local halo subdwarfs are representative,
then the Milky Way's dark halo is oblate with a flattening in the potential of
g ~ 0.85, corresponding to a flattening in the dark matter density of ~ 0.7.
The fractional pressure excess for power-law populations is roughly
proportional to both the ellipticity and the fall-off exponent. Given the same
pressure excess, if the density profile of one stellar population declines more
quickly than that of another, then it must be rounder. This implies that the
dual halo structure claimed by Carollo et al. (2007) for the Galaxy, a flatter
inner halo and a rounder outer halo, is inconsistent with the virial theorem.
For the thick disc, we provide formulae for the virial sequences of
double-exponential discs in logarithmic and Navarro-Frenk-White (NFW) haloes.
There are good matches to the observational data on the flattening and
anisotropy of the thick disc if the thin disc is exponential with a short
scalelength ~ 2.6 kpc and normalisation of 56 solar masses per square parsec,
together with a logarithmic dark halo.Comment: MNRAS, submitted, 13 pages, 7 figures, small changes to made to
correspond to final accepted versio
Increased HIV Incidence in Men Who Have Sex with Men Despite High Levels of ART-Induced Viral Suppression: Analysis of an Extensively Documented Epidemic
Background: There is interest in expanding ART to prevent HIV transmission, but in the group with the highest levels of ART use, men-who-have-sex-with-men (MSM), numbers of new infections diagnosed each year have not decreased as ART coverage has increased for reasons which remain unclear.
Methods: We analysed data on the HIV-epidemic in MSM in the UK from a range of sources using an individual-based simulation model. Model runs using parameter sets found to result in good model fit were used to infer changes in HIV-incidence and risk behaviour.
Results: HIV-incidence has increased (estimated mean incidence 0.30/100 person-years 1990–1997, 0.45/100 py 1998–2010), associated with a modest (26%) rise in condomless sex. We also explored counter-factual scenarios: had ART not been introduced, but the rise in condomless sex had still occurred, then incidence 2006–2010 was 68% higher; a policy of ART initiation in all diagnosed with HIV from 2001 resulted in 32% lower incidence; had levels of HIV testing been higher (68% tested/year instead of 25%) incidence was 25% lower; a combination of higher testing and ART at diagnosis resulted in 62% lower incidence; cessation of all condom use in 2000 resulted in a 424% increase in incidence. In 2010, we estimate that undiagnosed men, the majority in primary infection, accounted for 82% of new infections.
Conclusion: A rise in HIV-incidence has occurred in MSM in the UK despite an only modest increase in levels of condomless sex and high coverage of ART. ART has almost certainly exerted a limiting effect on incidence. Much higher rates of HIV testing combined with initiation of ART at diagnosis would be likely to lead to substantial reductions in HIV incidence. Increased condom use should be promoted to avoid the erosion of the benefits of ART and to prevent other serious sexually transmitted infections
Reconstructions of deltaic environments from Holocene palynological records in the Volga delta, northern Caspian Sea
This article was made available through open access by the Brunel Open Access Publishing Fund.New palynological and ostracod data are presented from the Holocene Volga delta, obtained from short cores and surface samples collected in the Damchik region, near Astrakhan, Russian Federation in the northern Caspian Sea. Four phases of delta deposition are recognized and constrained by accelerated mass spectrometry (AMS) radiocarbon ages. Palynological records show that erosive channels, dunes (Baer hills) and inter-dune lakes were present during the period 11,500–8900 cal. BP at the time of the Mangyshlak Caspian lowstand. The period 8900–3770 cal. BP was characterized regionally by extensive steppe vegetation, with forest present at times with warmer, more humid climates, and with halophytic and xerophytic vegetation present at times of drought. The period 3770–2080 cal. BP was a time of active delta deposition, with forest or woodland close to the delta, indicating relatively warm and humid climates and variable Caspian Sea levels. From 2080 cal. BP to the present-day, aquatic pollen is frequent in highstand intervals and herbaceous pollen and fungal hyphae frequent in lowstand intervals. Soils and incised valley sediments are associated with the regional Derbent regression and may be time-equivalent with the ‘Medieval Warm Period’. Fungal spores are an indicator of erosional or aeolian processes, whereas fungal hyphae are associated with soil formation. Freshwater algae, ostracods and dinocysts indicate mainly freshwater conditions during the Holocene with minor brackish influences. Dinocysts present include Spiniferites cruciformis, Caspidinium rugosum, Impagidinium caspienense and Pterocysta cruciformis, the latter a new record for the Caspian Sea. The Holocene Volga delta is a partial analogue for the much larger oil and gas bearing Mio-Pliocene palaeo-Volga delta.Funding for the data collection and field work was provided from the following sources: 1 – IGCP-UNESCO 2003–2008 (Project 481 CASPAGE, Dating Caspian Sea Level Change); 2 – NWO, Netherlands Science Foundation and RFFI, Russian Science Foundation 2005–2008 (Programme: ‘VHR Seismic Stratigraphy and Paleoecology of the Holocene Volga Delta’); and 3 – BP Exploration (Caspian Sea) Sea Ltd. (Azeri-Chirag-Gunashli) 2005–2008 (‘Unravelling the Small-Scale Stratigraphy and Sediment Dynamics of the Modern Volga Delta Using VHR Marine Geophysics’). The palynological work was funded jointly by BP Exploration (Caspian Sea) Ltd., Delft University of Technology and KrA Stratigraphic Ltd. Ostracod analyses were funded by StrataData Ltd. and funding for two additional radiocarbon dates provided by Deltares
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