837 research outputs found
Calcaneal BMD Obtained by Dual X-Ray and Laser Predicts Future Hip FracturesâA Prospective Study on 4â398 Swedish Women
The predictive value of dual X-ray and laser (DXL) calcaneal BMD (BMDDXL) on hip fractures was prospectively studied in 4,398 females aged 55 to 99 years. The average follow-up period was 3 years and 11 months with a total of 17,270 person years. Fractures were identified from the national patient register. After inclusion, 130 females sustained a hip fracture. The age adjusted hazard ratio for T-score <â2.5 versus >â2.5 was 2.64. Of all patients who sustained a hip fracture 78% had a T-score of â2.5 or below. The annual hip fracture rate was 0.26% at T-scores â„â2, but 1.5% at T-scores â€â2.5. The area under curve for the model including calcaneal BMDDXL, follow-up time, and age to prospectively predict hip fractures was 0.84. Conclusions. Calcaneal BMDDXL obtained by DXL Calscan predicts hip fractures and may therefore be suitable for diagnosing osteoporosis and for predicting fracture risk
Extinction Curves of Lensing Galaxies out to z=1
We present a survey of the extinction properties of ten lensing galaxies, in the redshift range z = 0.04 - 1.01, using multiply lensed quasars imaged with the ESO VLT in the optical and near infrared. The multiple images act as 'standard light sources' shining through different parts of the lensing galaxy, allowing for extinction studies by comparison of pairs of images. We explore the effects of systematics in the extinction curve analysis, including extinction along both lines of sight and microlensing, using theoretical analysis and simulations. In the sample, we see variation in both the amount and type of extinction. Of the ten systems, seven are consistent with extinction along at least one line of sight. The mean differential extinction for the most extinguished image pair for each lens is A(V) = 0.56 +- 0.04, using Galactic extinction law parametrization. The corresponding mean R_V = 2.8 +- 0.4 is consistent with that of the Milky Way at R_V = 3.1, where R_V = A(V)/E(B-V). We do not see any strong evidence for evolution of extinction properties with redshift. Of the ten systems, B1152+199 shows the strongest extinction signal of A(V) = 2.43 +- 0.09 and is consistent with a Galactic extinction law with R_V = 2.1 +- 0.1. Given the similar redshift distribution of SN Ia hosts and lensing galaxies, a large space based study of multiply imaged quasars would be a useful complement to future dark energy SN Ia surveys, providing independent constraints on the statistical extinction properties of galaxies up to z~1
The extinction law in high redshift galaxies
We estimate the dust extinction laws in two intermediate redshift galaxies.
The dust in the lens galaxy of LBQS1009-0252, which has an estimated lens
redshift of zl~0.88, appears to be similar to that of the SMC with no
significant feature at 2175 A. Only if the lens galaxy is at a redshift of
zl~0.3, completely inconsistent with the galaxy colors, luminosity or location
on the fundamental plane, can the data be fit with a normal Galactic extinction
curve. The dust in the zl=0.68 lens galaxy for B0218+357, whose reddened image
lies behind a molecular cloud, requires a very flat ultraviolet extinction
curve with (formally) R(V)=12 +- 2. Both lens systems seem to have unusual
extinction curves by Galactic standards.Comment: 15 pages, 3 figures. ApJ in pres
A high stellar velocity dispersion for a compact massive galaxy at z=2.2
Recent studies have found that the oldest and most luminous galaxies in the
early Universe are surprisingly compact, having stellar masses similar to
present-day elliptical galaxies but much smaller sizes. This finding has
attracted considerable attention as it suggests that massive galaxies have
grown by a factor of ~five in size over the past ten billion years. A key test
of these results is a determination of the stellar kinematics of one of the
compact galaxies: if the sizes of these objects are as extreme as has been
claimed, their stars are expected to have much higher velocities than those in
present-day galaxies of the same mass. Here we report a measurement of the
stellar velocity dispersion of a massive compact galaxy at redshift z=2.186,
corresponding to a look-back time of 10.7 billion years. The velocity
dispersion is very high at 510 (+165, -95) km/s, consistent with the mass and
compactness of the galaxy inferred from photometric data and indicating
significant recent structural and dynamical evolution of massive galaxies. The
uncertainty in the dispersion was determined from simulations which include the
effects of noise and template mismatch. However, we caution that some subtle
systematic effect may influence the analysis given the low signal-to-noise
ratio of our spectrum.Comment: Accepted as a Letter to Nature. A press release will be issued at the
time of publicatio
Mapping Obscuration to Reionization with ALMA (MORA): 2 mm Efficiently Selects the Highest-redshift Obscured Galaxies
We present the characteristics of 2 mm selected sources from the largest Atacama Large Millimeter/submillimeter Array (ALMA) blank-field contiguous survey conducted to date, the Mapping Obscuration to Reionization with ALMA (MORA) survey covering 184 arcmin2 at 2 mm. Twelve of 13 detections above 5Ï are attributed to emission from galaxies, 11 of which are dominated by cold dust emission. These sources have a median redshift of primarily based on optical/near-infrared photometric redshifts with some spectroscopic redshifts, with 77% ± 11% of sources at z > 3 and 38% ± 12% of sources at z > 4. This implies that 2 mm selection is an efficient method for identifying the highest-redshift dusty star-forming galaxies (DSFGs). Lower-redshift DSFGs (z < 3) are far more numerous than those at z > 3 yet are likely to drop out at 2 mm. MORA shows that DSFGs with star formation rates in excess of 300 M â yrâ1 and a relative rarity of âŒ10â5 Mpcâ3 contribute âŒ30% to the integrated star formation rate density at 3 < z < 6. The volume density of 2 mm selected DSFGs is consistent with predictions from some cosmological simulations and is similar to the volume density of their hypothesized descendants: massive, quiescent galaxies at z > 2. Analysis of MORA sourcesâ spectral energy distributions hint at steeper empirically measured dust emissivity indices than reported in typical literature studies, with . The MORA survey represents an important step in taking census of obscured star formation in the universeâs first few billion years, but larger area 2 mm surveys are needed to more fully characterize this rare population and push to the detection of the universeâs first dusty galaxies
Improved constraints on the expansion rate of the Universe up to z~1.1 from the spectroscopic evolution of cosmic chronometers
We present new improved constraints on the Hubble parameter H(z) in the
redshift range 0.15 < z < 1.1, obtained from the differential spectroscopic
evolution of early-type galaxies as a function of redshift. We extract a large
sample of early-type galaxies (\sim11000) from several spectroscopic surveys,
spanning almost 8 billion years of cosmic lookback time (0.15 < z < 1.42). We
select the most massive, red elliptical galaxies, passively evolving and
without signature of ongoing star formation. Those galaxies can be used as
standard cosmic chronometers, as firstly proposed by Jimenez & Loeb (2002),
whose differential age evolution as a function of cosmic time directly probes
H(z). We analyze the 4000 {\AA} break (D4000) as a function of redshift, use
stellar population synthesis models to theoretically calibrate the dependence
of the differential age evolution on the differential D4000, and estimate the
Hubble parameter taking into account both statistical and systematical errors.
We provide 8 new measurements of H(z) (see Tab. 4), and determine its change in
H(z) to a precision of 5-12% mapping homogeneously the redshift range up to z
\sim 1.1; for the first time, we place a constraint on H(z) at z \neq 0 with a
precision comparable with the one achieved for the Hubble constant (about 5-6%
at z \sim 0.2), and covered a redshift range (0.5 < z < 0.8) which is crucial
to distinguish many different quintessence cosmologies. These measurements have
been tested to best match a \Lambda CDM model, clearly providing a
statistically robust indication that the Universe is undergoing an accelerated
expansion. This method shows the potentiality to open a new avenue in constrain
a variety of alternative cosmologies, especially when future surveys (e.g.
Euclid) will open the possibility to extend it up to z \sim 2.Comment: 34 pages, 15 figures, 6 tables, published in JCAP. It is a companion
to Moresco et al. (2012b, http://arxiv.org/abs/1201.6658) and Jimenez et al.
(2012, http://arxiv.org/abs/1201.3608). The H(z) data can be downloaded at
http://www.physics-astronomy.unibo.it/en/research/areas/astrophysics/cosmology-with-cosmic-chronometer
Young disabled and LGBT+: negotiating identity
Disabled people are historically de-sexualized and labelled as non-sexual, incapable or uninterested in sex/relationships. This perception does much to reinforce social inequalities and misconceptions about disabled sexuality and gender. For young people who are LGBTâ+âthe task of negotiating their identity and making sense of who they are is challenging. Not only is their sexuality and gender invalidated by wider society, they are also marginalized and largely unsupported during a period of intense identity negotiation. Presenting findings from a UK-based qualitative project, this article explores how in the light of such challenges, young disabled LGBTâ+âpeople understand, negotiate and enact their identities
Fetal loss and maternal serum levels of 2,2',4,4',5,5'-hexachlorbiphenyl (CB-153) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE) exposure: a cohort study in Greenland and two European populations
<p>Abstract</p> <p>Background</p> <p>In the present study, the aim is to examine the risk of fetal loss related to environmental 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) or 1,1-dichloro-2,2-bis(<it>p</it>-chlorophenyl)ethylene (p,p'-DDE) exposure.</p> <p>Methods</p> <p>We related LC/MS/MS measurements of CB-153 and p,p'-DDE in serum samples to interview-data on previous fetal loss in populations of pregnant women from Poland, Ukraine and Greenland.</p> <p>Results</p> <p>In total, 1710 women were interviewed, and 678 of these had at least one previous pregnancy. The risk of ever experiencing a fetal loss increased at higher levels of CB-153 and p,p'-DDE exposure, with an adjusted odds ratio (OR) of 2.4; confidence interval (CI) (1.1-5.5) for CB-153>200 ng/g lipid compared to 0-25 ng CB-153/g lipid and OR of 2.5 CI (0.9-6.6) for p,p'-DDE>1500 ng/g lipid compared to 0-250 ng DDE/g lipid. However, no clear dose response associations were observed. The results further suggest that high level of organochlorine serum concentrations may be related to repeated loss.</p> <p>Conclusions</p> <p>The risk of fetal loss may increase at higher levels of CB-153 and p,p'-DDE exposure, although lack of dose response and inconsistencies between countries did not allow for firm conclusions.</p
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