770 research outputs found
Ultraviolet Luminosity Density of the Universe During the Epoch of Reionization
The spatial fluctuations of the extragalactic background light trace the
total emission from all stars and galaxies in the Universe. A multi-wavelength
study can be used to measure the integrated emission from first galaxies during
reionization when the Universe was about 500 million years old. Here we report
arcminute-scale spatial fluctuations in one of the deepest sky surveys with the
Hubble Space Telescope in five wavebands between 0.6 and 1.6 m. We
model-fit the angular power spectra of intensity fluctuation measurements to
find the ultraviolet luminosity density of galaxies at > 8 to be erg s Hz Mpc
. This level of integrated light emission allows for a significant
surface density of fainter primeval galaxies that are below the point source
detection level in current surveys.Comment: The official typeset version is available from the Nature
Communications website at
http://www.nature.com/ncomms/2015/150907/ncomms8945/full/ncomms8945.html The
data used in this work can be found at http://herschel.uci.edu/CANDELS
âYou have to keep track of your changesâ: The Version Variants and Publishing History of David Mitchell's Cloud Atlas
In 2003, David Mitchellâs editorial contact at the US branch of Random House moved from the publisher, leaving the American edition of Cloud Atlas (2004) without an editor for approximately three months. Meanwhile, the UK edition of the manuscript was undergoing a series of editorial changes and rewrites that were never synchronised back into the US edition of the text. When the process was resumed at Random House under the editorial guidance of David Ebershoff, changes from New York were likewise not imported back into the UK edition. In the section entitled âAn Orison of Sonmi~451â these desynchronised rewritings are nearly total at the level of linguistic expression between UK and US paperbacks/electronic editions and there are a range of sub-episodes that only feature in one or other of the published editions. Within the constraints of copyright on contemporary fiction, this article sets out this textual variance and visually plots the re-ordering and re-writing of the Sonmi section of the novel across versions. Further to this, I also signal here a number of reasons why critics might need to consider the production processes of contemporary fiction in order to deal with the multiple and different editions of this text and other contemporary novels
Two-component Coulomb Glass in Disordered Superconducting Films
Motivated by evidence of local electron-electron attraction in experiments on
disordered insulating films, we propose a new two-component Coulomb glass model
that combines strong disorder and long-range Coulomb repulsion with the
additional possibility of local pockets of a short-range inter-electron
attraction. This model hosts a variety of interesting phenomena, in particular
a crucial modification of the Coulomb gap previously believed to be universal.
Tuning the short-range interaction to be repulsive, we find non-monotonic humps
in the density of states within the Coulomb gap. We further study
variable-range hopping transport in such systems by extending the standard
resistor network approach to include the motion of both single electrons and
local pairs. In certain parameter regimes the competition between these two
types of carriers results in a distinct peak in resistance as a function of the
local attraction strength, which can be tuned by a magnetic field.Comment: 12 pages, 6 figure
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Population genomics of post-vaccine changes in pneumococcal epidemiology
Whole genome sequencing of 616 asymptomatically carried pneumococci was used to study the impact of the 7-valent pneumococcal conjugate vaccine. Comparison of closely related isolates revealed the role of transformation in facilitating capsule switching to non-vaccine serotypes and the emergence of drug resistance. However, such recombination was found to occur at significantly different rates across the species, and the evolution of the population was primarily driven by changes in the frequency of distinct genotypes extant pre-vaccine. These alterations resulted in little overall effect on accessory genome composition at the population level, contrasting with the fall in pneumococcal disease rates after the vaccineâs introduction
WHAT GOOD IS WEALTH WITHOUT HEALTH? THE EFFECT OF HEALTH ON THE MARGINAL UTILITY OF CONSUMPTION
We estimate how the marginal utility of consumption varies with health. To do so, we develop a simple model in which the impact of health on the marginal utility of consumption can be estimated from data on permanent income, health, and utility proxies. We estimate the model using the Health and Retirement Study's panel data on the elderly and near-elderly, and proxy for utility with measures of subjective well-being. Across a wide range of alternative specifications and assumptions, we find that the marginal utility of consumption declines as health deteriorates, and we are able to clearly reject the null of no state dependence. Our point estimates indicate that a one-standard-deviation increase in the number of chronic diseases is associated with a 10%â25% decline in the marginal utility of consumption relative to this marginal utility when the individual has no chronic diseases. We present some simple, illustrative calibration results that suggest that state dependence of the magnitude we estimate can have a substantial effect on important economic problems such as the optimal level of health insurance benefits and the optimal level of life-cycle savings.United States. Social Security Administration (National Bureau of Economic Research Grant 10-P-98363-1-05)National Institute on Aging (Grant T32-AG000186
Design and Tests of the Hard X-ray Polarimeter X-Calibur
X-ray polarimetry promises to give qualitatively new information bout high-energy astrophysical sources, such as binary black hole  systems, micro-quasars, active galactic nuclei, and gamma-ray bursts. We designed, built and tested ahard X-ray polarimeter, X-Calibur, to be used in the focal plane of the InFOCuS grazing incidence hard X-ray telescope.X-Calibur combines a low-Z Compton scatterer with a CZT detector assembly to measure the polarization of 20â60 keV X-rays making use of the fact that polarized photons Compton scatter preferentially perpendicular to the electric field orientation; in principal, a similar space-borne experiment could be operated in the 5â100 keV regime. X-Calibur achieves a high detection efficiency of order unity
Does High BMI Influence Hospital Charges in Children Undergoing Adenotonsillectomy?
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93757/1/oby.2008.234.pd
Longevity risk management in Singapore's national pension system
Although annuities are a theoretically appealing way to manage longevity risk, in the real world relatively few consumers purchase them at retirement. To counteract the possibility of retirees outliving their assets, Singapore\u27s Central Provident Fund, a national defined contribution pension scheme, has recently mandated annuitization of workersâ retirement assets. More significantly, the government has entered the insurance market as a public-sector provider for such annuities. This article evaluates the money\u27s worth of life annuities and discusses the impact of the government mandate and its role as an annuity provider on the insurance market
High-Dose-Rate Brachytherapy for the Treatment of Basal and Squamous Cell Carcinomas on Sensitive Areas of the Face: A Report of Clinical Outcomes and Acute and Subacute Toxicities
Purpose Basal cell and cutaneous squamous cell carcinoma are common malignancies (keratinocyte carcinomas [KCs]). Surgical resection is the standard of care. Radiation using high-dose rate brachytherapy (HDR-BT) may serve as a superior alternative where surgical scars may be of cosmetic concern or in elderly patients with significant comorbidity. We aim to describe the clinical and cosmetic outcomes as well as posttreatment radiation toxicities associated with HDR-BT in patients who were treated for KCs of the face.
Methods and Materials Patients with KCs treated with HDR-BT from 2015 to 2018 were included in the study. Patient medical records and clinical photos were reviewed at multiple time points: start of treatment, end of treatment, short-term (2 week) follow-up, 3-month follow-up, and if needed at 6 months. Radiation toxicity was graded using the Radiation Therapy Oncology Grading (RTOG) acute toxicity scale. Median (range) toxicity grades at follow-up intervals were calculated. Clinical outcomes including local recurrence were evaluated for all patients.
Results The study included 19 patients and 20 KCs. The median radiation dose was 42 Gy (39-42 Gy) over 6 fractions. The median toxicity at completion of treatment was RTOG grade 2 (85% of patients). At short-term follow-up, 50% of patients (n = 10) improved to RTOG grade 1 (0-2). At 3 months, 70% of patients (n = 14) had RTOG grade 0, and by 6 months, 100% of patients (n = 18) had RTOG grade 0. No RTOG grade 3 or higher skin toxicity was observed. With a median follow-up of 7.2 months (range, 1.3-54.4 months), the local recurrence-free survival was 95%.
Conclusions We demonstrate that HDR-BT can be used as definitive treatment of KCs of the face with excellent cosmetic outcomes and local control. Acute and subacute skin toxicities were most commonly RTOG grade 2 or less with resolution of patientâs skin toxicity by 3 months
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Age-dependent investing: Optimal funding and investment strategies in defined contribution pension plans when members are rational life cycle financial planners
A defined contribution pension plan allows consumption to be redistributed from the plan member's working life to retirement in a manner that is consistent with the member's personal preferences. The plan's optimal funding and investment strategies therefore depend on the desired profile of consumption over the lifetime of the member. We investigate these strategies under the assumption that the member is a rational life cycle financial planner and has an Epstein-Zin utility function, which allows a separation between risk aversion and the elasticity of intertemporal substitution. We also take into account the member's human capital during the accumulation phase of the plan and we allow the annuitisation decision to be endogenously determined during the decumulation phase. We show that the optimal funding strategy involves a contribution rate that is not constant over the life of the plan but is age-dependent and reflects the trade-off between the desire for current versus future consumption, the desire for stable consumption over time, the member's attitude to risk, and changes in the level of human capital over the life cycle. We also show that the optimal investment strategy during the accumulation phase of the plan is 'stochastic lifestyling', with an initial high weight in equity-type investments and a gradual switch into bond-type investments as the retirement date approaches in a way that depends on the realised outcomes for the stochastic processes driving the state variables. The optimal investment strategy during the decumulation phase of the plan is to exchange the bonds held at retirement for life annuities and then to gradually sell the remaining equities and buy more annuities, i.e., a strategy known as 'phased annuitisation'
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