5,697 research outputs found
Galactic Scale Feedback Observed in the 3C 298 Quasar Host Galaxy
We present high angular resolution multi-wavelength data of the 3C 298
radio-loud quasar host galaxy (z=1.439) taken using the W.M. Keck Observatory
OSIRIS integral field spectrograph with adaptive optics, Atacama Large
Millimeter/submillimeter Array (ALMA), Hubble Space Telescope (HST) WFC3, and
the Very Large Array (VLA). Extended emission is detected in the rest-frame
optical nebular emission lines H, [OIII], H, [NII], and [SII],
as well as molecular lines CO (J=3-2) and (J=5-4). Along the path of 3C 298's
relativistic jets we detect conical outflows of ionized gas with velocities up
to 1700 km s and outflow rate of 450-1500 Myr. Near the
spatial center of the conical outflow, CO (J=3-2) emission shows a molecular
gas disc with a total molecular mass () of
6.6M. On the molecular disc's blueshifted side
we observe a molecular outflow with a rate of 2300 Myr and
depletion time scale of 3 Myr. We detect no narrow H emission in the
outflow regions, suggesting a limit on star formation of 0.3
Myrkpc. Quasar driven winds are evacuating the molecular
gas reservoir thereby directly impacting star formation in the host galaxy. The
observed mass of the supermassive black hole is M and
we determine a dynamical bulge mass of 1-1.7
M. The bulge mass of 3C 298 resides 2-2.5 orders of magnitude below
the expected value from the local M relationship. A second
galactic disc observed in nebular emission is offset from the quasar by 9 kpc
suggesting the system is an intermediate stage merger. These results show that
galactic scale negative feedback is occurring early in the merger phase of 3C
298, well before the coalescence of the galactic nuclei and assembly on the
local relationship.Comment: 23 pages, 11 figures, 4 tables, Accepted for publication in the
Astrophysical Journa
Metformin as a Therapeutic Target in Endometrial Cancers.
Endometrial cancer is the most common gynecologic malignancy in developed countries. Its increasing incidence is thought to be related in part to the rise of metabolic syndrome, which has been shown to be a risk factor for the development of hyperestrogenic and hyperinsulinemic states. This has consequently lead to an increase in other hormone-responsive cancers as well e.g., breast and ovarian cancer. The correlation between obesity, hyperglycemia, and endometrial cancer has highlighted the important role of metabolism in cancer establishment and persistence. Tumor-mediated reprogramming of the microenvironment and macroenvironment can range from induction of cytokines and growth factors to stimulation of surrounding stromal cells to produce energy-rich catabolites, fueling the growth, and survival of cancer cells. Such mechanisms raise the prospect of the metabolic microenvironment itself as a viable target for treatment of malignancies. Metformin is a biguanide drug that is a first-line treatment for type 2 diabetes that has beneficial effects on various markers of the metabolic syndrome. Many studies suggest that metformin shows potential as an adjuvant treatment for uterine and other cancers. Here, we review the evidence for metformin as a treatment for cancers of the endometrium. We discuss the available clinical data and the molecular mechanisms by which it may exert its effects, with a focus on how it may alter the tumor microenvironment. The pleiotropic effects of metformin on cellular energy production and usage as well as intercellular and hormone-based interactions make it a promising candidate for reprogramming of the cancer ecosystem. This, along with other treatments aimed at targeting tumor metabolic pathways, may lead to novel treatment strategies for endometrial cancer
Time-energy correlations in solar flare occurrence
The existence of time-energy correlations in flare occurrence is still an
open and much debated problem. This study addresses the question whether
statistically significant correlations are present between energies of
successive flares as well as energies and waiting times. We analyze the GOES
catalog with a statistical approach based on the comparison of the real catalog
with a reshuffled one where energies are decorrelated. This analysis reduces
the effect of background activity and is able to reveal the role of
obscuration. We show the existence of non-trivial correlations between waiting
times and energies, as well as between energies of subsequent flares. More
precisely, we find that flares close in time tend to have the second event with
large energy. Moreover, after large flares the flaring rate significantly
increases, together with the probability of other large flares. Results suggest
that correlations between energies and waiting times are a physical property
and not an effect of obscuration. These findings could give important
information on the mechanisms for energy storage and release in the solar
corona
Maternal obesity during pregnancy and premature mortality from cardiovascular event in adult offspring : follow-up of 1 323 275 person years
Peer reviewedPublisher PD
Temperature dependent characterization of optical fibres for distributed temperature sensing in hot geothermal wells
This study was performed in order to select a proper fibre for the
application of a distributed temperature sensing system within a hot geothermal
well in Iceland. Commercially available high temperature graded index fibres
have been tested under in-situ temperature conditions. Experiments have been
performed with four different polyimide coated fibres, a fibre with an aluminum
coating and a fibre with a gold coating. To select a fibre, the relationship
between attenuation, temperature, and time has been analyzed together with SEM
micrographs. On the basis of these experiments, polyimide fibres have been
chosen for utilisation. Further tests in ambient and inert atmosphere have been
conducted with two polyimide coated fibres to set an operating temperature
limit for these fibres. SEM micrographs, together with coating colour changes
have been used to characterize the high temperature performance of the fibres.
A novel cable design has been developed, a deployment strategy has been worked
out and a suitable well for deployment has been selected.Comment: PACS: 42.81.Pa, 93.85.Fg, 47.80.Fg, 91.35.Dc, 07.20.Dt, 07.60.V
Postal recruitment for genetic studies of preterm birth: A feasibility study.
Background: Preterm birth (PTB) represents the leading cause of neonatal death. Large-scale genetic studies are necessary to determine genetic influences on PTB risk, but prospective cohort studies are expensive and time-consuming. We investigated the feasibility of retrospective recruitment of post-partum women for efficient collection of genetic samples, with self-collected saliva for DNA extraction from themselves and their babies, alongside self-recollection of pregnancy and birth details to phenotype PTB. Methods: 708 women who had participated in the OPPTIMUM trial (a randomised trial of progesterone pessaries to prevent PTB [ISRCTN14568373]) and consented to further contact were invited to provide self-collected saliva from themselves and their babies. DNA was extracted from Oragene OG-500 (adults) and OG-575 (babies) saliva kits and the yield measured by Qubit. Samples were analysed using a panel of Taqman single nucleotide polymorphism (SNP) assays. A questionnaire designed to meet the minimum data set required for phenotyping PTB was included. Questionnaire responses were transcribed and analysed for concordance with prospective trial data using Cohen's kappa ( k). Results: Recruitment rate was 162/708 (23%) for self-collected saliva samples and 157/708 (22%) for questionnaire responses. 161 samples from the mother provided DNA with median yield 59.0”g (0.4-148.9”g). 156 samples were successfully genotyped (96.9%). 136 baby samples had a median yield 11.5”g (0.1-102.7”g); two samples failed DNA extraction. 131 baby samples (96.3%) were successfully genotyped. Concordance between self-recalled birth details and prospective birth details was excellent ( k>0.75) in 4 out of 10 key fields for phenotyping PTB (mode of delivery, labour onset, ethnicity and maternal age at birth). Conclusion: This feasibility study demonstrates that self-collected DNA samples from mothers and babies were sufficient for genetic analysis but yields were variable. Self-recollection of pregnancy and birth details was inadequate for accurately phenotyping PTB, highlighting the need for alternative strategies for investigating genetic links with PTB
Fourier transform spectroscopy of d-wave quasiparticles in the presence of atomic scale pairing disorder
The local density of states power spectrum of optimally doped
BiSrCaCuO (BSCCO) has been interpreted in terms of
quasiparticle interference peaks corresponding to an "octet'' of scattering
wave vectors connecting k-points where the density of states is maximal. Until
now, theoretical treatments have not been able to reproduce the experimentally
observed weights and widths of these "octet'' peaks; in particular, the
predominance of the dispersing "q'' peak parallel to the Cu-O bond
directions has remained a mystery. In addition, such theories predict
"background'' features which are not observed experimentally. Here, we show
that most of the discrepancies can be resolved when a realistic model for the
out-of-plane disorder in BSCCO is used. Weak extended potential scatterers,
which are assumed to represent cation disorder, suppress large-momentum
features and broaden the low-energy "q''-peaks, whereas scattering at order
parameter variations, possibly caused by a dopant-modulated pair interaction
around interstitial oxygens, strongly enhances the dispersing "q''-peaks.Comment: 7 pages, 3 figure
IROCKS: Spatially Resolved Kinematics of z ~ 1 Star-forming Galaxies
We present results from the Intermediate Redshift OSIRIS Chemo-Kinematic Survey (IROCKS) for sixteen z ~ 1 and one z ~ 1.4 star-forming galaxies. All galaxies were observed with OSIRIS with the laser guide star adaptive optics system at Keck Observatory. We use rest-frame nebular Hα emission lines to trace morphologies and kinematics of ionized gas in star-forming galaxies on sub-kiloparsec physical scales. We observe elevated velocity dispersions (Ï âł 50 km s^(â1)) seen in z > 1.5 galaxies persist at z ~ 1 in the integrated galaxies. Using an inclined disk model and the ratio of v/Ï, we find that 1/3 of the z ~ 1 sample are disk candidates while the other 2/3 of the sample are dominated by merger-like and irregular sources. We find that including extra attenuation toward H ii regions derived from stellar population synthesis modeling brings star formation rates (SFRs) using Hα and stellar population fit into a better agreement. We explore the properties of the compact Hα sub-component, or "clump," at z ~ 1 and find that they follow a similar sizeâluminosity relation as local H ii regions but are scaled-up by an order of magnitude with higher luminosities and sizes. Comparing the z ~ 1 clumps to other high-redshift clump studies, we determine that the clump SFR surface density evolves as a function of redshift. This suggests clump formation is directly related to the gas fraction in these systems and may support disk fragmentation as their formation mechanism since gas fraction scales with redshift
Classical and Quantum Interaction of the Dipole
A unified and fully relativistic treatment of the interaction of the electric
and magnetic dipole moments of a particle with the electromagnetic field is
given. New forces on the particle due to the combined effect of electric and
magnetic dipoles are obtained. Four new experiments are proposed, three of
which would observe topological phase shifts.Comment: 10 pages, Latex/Revtex. Some minor errors have been correcte
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