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Fully compliant? : a study of data protection policy in UK public organisations
EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Signs of Binary Evolution in 7 Magnetic DA White Dwarfs
We present our findings on the spectral analysis of seven magnetic white
dwarfs that were presumed to be double degenerates. We obtained time-resolved
spectroscopy at the Gemini Observatory to look for evidence of binarity or fast
rotation. We find three of our targets have rotation periods of less than an
hour based on the shifting positions of the Zeeman-split H components:
13, 35, and 39 min, and we find one more target with a ~hour long period that
is currently unconstrained. We use offset dipole models to determine the
inclination, magnetic field strength, and dipole offset of each target. The
average surface field strengths of our fast rotators vary by 1-2 MG between
different spectra. In all cases, the observed absorption features are too
shallow compared to our models. This could be due to extra flux from a
companion for our three low-mass targets, but the majority of our sample likely
requires an inhomogeneous surface composition. Including an additional magnetic
white dwarf with similar properties presented in the literature, we find that 5
of the 8 targets in this sample show field variations on minute/hour
timescales. A crystallization driven dynamo can potentially explain the
magnetic fields in three of our targets with masses above but
another mechanism is still needed to explain their rapid rotation. We suggest
that rapid rotation or low-masses point to binary evolution as the likely
source of magnetism in 7 of these 8 targets.Comment: 13 pages, 14 figures, accepted for publication in MNRA
A New Einstein Cross: A Highly Magnified, Intrinsically Faint Lyman-Alpha Emitter at z=2.7
We report the discovery of a new Einstein cross at redshift z_S = 2.701 based
on Lyman-alpha emission in a cruciform configuration around an SDSS luminous
red galaxy (z_L = 0.331). The system was targeted as a possible lens based on
an anomalous emission line in the SDSS spectrum. Imaging and spectroscopy from
the W. M. Keck Observatory confirm the lensing nature of this system. This is
one of the widest-separation galaxy-scale lenses known, with an Einstein radius
of ~1.84 arcsec. We present simple gravitational lens models for the system and
compute the intrinsic properties of the lensed galaxy. The total mass of the
lensing galaxy within the 8.8 +/- 0.1 kpc enclosed by the lensed images is (5.2
+/- 0.1) x 10^11 M_sun. The lensed galaxy is a low mass galaxy (0.2 L*) with a
high equivalent-width Lyman-alpha line (EW_Lya_rest = 46 +/- 5 Angstroms).
Follow-up studies of this lens system can probe the mass structure of the
lensing galaxy, and can provide a unique view of an intrinsically faint,
high-redshift, star-forming galaxy at high signal-to-noise ratio.Comment: ApJ Letters, in pres
Sloan Digital Sky Survey Spectroscopic Lens Search. I. Discovery of Intermediate-Redshift Star-Forming Galaxies Behind Foreground Luminous Red Galaxies
We present a catalog of 49 spectroscopic strong gravitational lens candidates
selected from a Sloan Digital Sky Survey sample of 50996 luminous red galaxies.
Potentially lensed star-forming galaxies are detected through the presence of
background oxygen and hydrogen nebular emission lines in the spectra of these
massive foreground galaxies. This multiline selection eliminates the ambiguity
of single-line identification and provides a very promising sample of candidate
galaxy-galaxy lens systems at low to intermediate redshift, with foreground
redshifts ranging from 0.16 to 0.49 and background redshifts from 0.25 to 0.81.
Any lenses confirmed within our sample would be important new probes of
early-type galaxy mass distributions, providing complementary constraints to
those obtained from currently known lensed high-redshift quasars.Comment: 23 pages; to appear in The Astronomical Journal, 2004 April. Version
with full-resolution figures available at
http://web.mit.edu/bolton/www/speclens.ps.gz (PostScript) or
http://web.mit.edu/bolton/www/speclens.pdf (PDF
PGC‑1α alternative promoter (Exon 1b) controls augmentation of total PGC‑1α gene expression in response to cold water immersion and low glycogen availability
This investigation sought to determine whether post-exercise cold water immersion and low glycogen availability, separately
and in combination, would preferentially activate either the Exon 1a or Exon 1b Peroxisome proliferator-activated
receptor gamma coactivator 1-alpha (PGC-1α) promoter. Through a reanalysis of sample design, we identified that the
systemic cold-induced augmentation of total PGC-1α gene expression observed previously (Allan et al. in J Appl Physiol
123(2):451–459, 2017) was largely a result of increased expression from the alternative promoter (Exon 1b), rather than
canonical promoter (Exon 1a). Low glycogen availability in combination with local cooling of the muscle (Allan et al. in
Physiol Rep 7(11):e14082, 2019) demonstrated that PGC-1α alternative promoter (Exon 1b) expression continued to rise at
3 h post-exercise in all conditions; whilst, expression from the canonical promoter (Exon 1a) decreased between the same
time points (post-exercise–3 h post-exercise). Importantly, this increase in PGC-1α Exon 1b expression was reduced compared
to the response of low glycogen or cold water immersion alone, suggesting that the combination of prior low glycogen and
CWI post-exercise impaired the response in gene expression versus these conditions individually. Data herein emphasise the
influence of post-exercise cooling and low glycogen availability on Exon-specific contro
Bergmann\u27s Clines in Ectotherms: Illustrating a Life-History Perspective with Sceloporine Lizards
The generality and causes of Bergmann\u27s rule have been debated vigorously in the last few years, but Bergmann\u27s clines are rarely explained in the context of life-history theory. We used both traditional and phylogenetic comparative analyses to explore the causes of latitudinal and thermal clines in the body size of the eastern fence lizard (Sceloporus undulatus). The proximate mechanism for larger body sizes in colder environments is delayed maturation, which results in a greater fecundity but a lower survival to maturity. Life-history theory predicts that a higher survivorship of juveniles in colder environments can favor the evolution of a Bergmann\u27s cline. Consistent with this theory, lizards in colder environments survive better as juveniles and delay maturation until reaching a larger body size than that of lizards in warmer environments. We expect similar relationships among temperature, survivorship, and age/size at maturity exist in other ectotherms that exhibit Bergmann\u27s clines. However, life-history traits of S. undulatus were more strongly related to latitude than they were to temperature, indicating that both abiotic and biotic factors should be considered as causes of Bergmann\u27s clines. Nonetheless, analyses of the costs and benefits of particular body sizes in different thermal environments will enhance our understanding of geographic variation
Post-exercise cold-water immersion modulates skeletal muscle PGC-1α mRNA expression in immersed and non-immersed limbs: evidence of systemic regulation
Mechanisms mediating post-exercise cold-induced increases in PGC-1α gene expression in human skeletal muscle are yet to be fully elucidated, but may involve local cooling effects on AMPK and p38 MAPK related signalling and/or increased systemic β-adrenergic stimulation. We aimed to therefore examine whether post-exercise cold-water immersion enhancement of PGC-1α mRNA is mediated through local or systemic mechanisms. Ten subjects completed acute cycling (8x5 min at ~80% peak power output) followed by seated-rest (CON) or single-leg cold-water immersion (CWI; 10 min, 8°C). Muscle biopsies were obtained pre-, post- and 3 h post-exercise from a single limb in the CON condition but from both limbs in CWI (thereby providing tissue from a CWI and non-immersed limb, NOT). Muscle temperature decreased up to 2 h post-exercise following CWI (-5°C) in the immersed limb, with lesser changes observed in CON and NOT (-3°C; P<0.05). No differences between limbs were observed in p38MAPK phosphorylation at any time point (P<0.05), whilst a significant interaction effect was present for AMPK phosphorylation (P=0.031). Exercise (CON) increased gene expression of PGC-1α 3 h post-exercise (~5-fold; P<0.001). CWI augmented PGC-1α expression above CON in both the immersed (CWI; ~9-fold; P=0.003) and NOT limbs (~12-fold; P=0.001). Plasma Normetanephrine concentration was higher in CWI vs. CON immediately post-immersion (860 vs. 665 pmol/L; P=0.034). We report for the first time that local cooling of the immersed limb evokes transcriptional control of PGC1-α in the non-immersed limb, suggesting increased systemic β-adrenergic activation of AMPK mediates, in part, post-exercise cold-induction of PGC-1α mRNA
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