2,682 research outputs found
Sex Differences in the Use and Evaluated Helpfulness of Premarital Advice
The purpose of this study was to explore sex differences in the use and evaluated helpfulness of advice received before marriage. In addition, this study explored who typically gave premarital advice. Advice is considered by some to be a form of social support which can be helpful or hurtful to the marriage relationship. The sex of the advice-giver and advice-receiver as well as the relationship quality between them was explored in order to highlight how these variables affect advice use and helpfulness. Utilizing a questionnaire and interviews with individual newlywed husbands (n = 56) and wives (n = 56), data were collected and analyzed. Advice was mostly given by mothers, fathers, friends, and religious leaders. Generally, both husbands and wives used the advice they were given and both evaluated the advice as helpful. Sex did not have a significant impact on advice use or helpfulness, but in some cases, the relationship between the advice-giver and advice-receiver significantly influenced the use and evaluated helpfulness of advice
Surface Direct Conversion of 511 keV Gamma Rays in Large-Area Laminated Multichannel-Plate Electron Multipliers
We have used the TOPAS simulation framework to model the direct conversion of
511 keV gamma rays to electrons in a micro-channel plate (MCP) constructed from
thin laminae of a heavy-metal-loaded dielectric such as lead-glass, patterned
with micro-channels (LMCP). The laminae serve as the converter of the gamma ray
to a primary electron within a depth from a channel-forming surface such that
the electron penetrates the channel surface ('surface direct conversion'). The
channels are coated with a secondary-emitting material to produce electron
multiplication in the channels. The laminae are stacked on edge with the
channels running from the top of the resulting 'slab' to the bottom; after
assembly the slab is metalized top and bottom to form the finished LMCP.
The shape of the perimeter of a lamina determines the dimensions of the slab
at the lamina location in the slab, allowing non-uniform cross-sections in slab
thickness, width, and length. The slab also can be non-planar, allowing curved
surfaces in both lateral dimensions. The laminar construction allows
incorporating structural elements in the LMCP for modular assembly in
large-area arrays.
The channels can be patterned on the laminae surfaces with internal shapes
and structure, texture, and coatings optimized for specific applications and
performance. The channels can be non-uniform across the LMCP and need not be
parallel in either transverse direction.
Surface direct conversion of the gamma ray to an electron eliminates the
common two-step conversion of the gamma ray into an optical photon in a
scintillator followed by the conversion of the photon into an electron in a
photodetector. The simulations predict an efficiency for conversion of 511 keV
gamma rays of approximately greater than 30% for a 2.54 cm-thick Pb-glass LMCP.
The elimination of the photocathode allows assembly at atmospheric pressure
Low-Dose TOF-PET Based on Surface Electron Production in Dielectric Laminar MCPs
We present simulations of whole-body low-dose time-of-flight positron
emission tomography (TOF-PET) based on the direct surface production [1] by 511
keV gamma rays of energetic electrons via the Photo-electric and Compton
Effects, eliminating the scintillator and photodetector sub-systems in PET
scanners. In Ref. [1] we described Microchannel Plates (MCP) constructed from
thin dielectric laminae containing heavy nuclei such as lead or tungsten
(LMCP). The laminae surfaces are micro-patterned to form channels,
which can then be functionalized to support secondary electron emission in the
manner of conventional MCPs.
We have simulated direct conversion using modifications to the TOPAS
Geant4-based tool kit. A 20 20 2.54 cm LMCP, composed of
150-micron thick lead-glass laminae, is predicted to have a %
conversion efficiency to a primary electron that penetrates an interior wall of
a pore. The subsequent secondary electron shower is largely confined to one
pore and can provide high space and time resolutions.
In whole-body PET scanners the technique eliminates the scintillator and
photodetector subsystems. The consequent absence of a photocathode allows
assembly of large arrays at atmospheric pressure and less stringent vacuum
requirements, including use of pumped and cycled systems.
TOPAS simulations of the Derenzo and XCAT-brain phantoms are presented with
dose reductions of factors of 100 and 1000 from a literature benchmark. New
applications of PET at a significantly lower radiation dose include routine
screening for early detection of pathologies, the use in diagnostics in
previously unserved patient populations such as children, and a larger
installed facility base in rural and under-served populations, where simpler
gamma detectors and lower radiation doses may enable small low-cost portable
PET scanners.Comment: Version 9d incorporates reviewer comments during revision process. 22
pages, 18 figure
Unemployment Risk and Wage Differentials
Workers in less secure jobs are often paid less than identical-looking workers in more secure
jobs. We show that this lack of compensating differentials for unemployment risk can arise in
equilibrium when all workers are identical, and firms differ, but do so only in offered job security
(the probability that the worker is not sent into unemployment). In a setting where workers search
on and off the job, wages paid increase with job security for at least all firms in the risky tail of the
distribution of firm-level unemployment risk. As a result, unemployment spells become persistent
for low-wage and unemployed workers, a seeming pattern of ‘unemployment scarring’, that is
created entirely by firm heterogeneity alone. Higher in the wage distribution, workers can take
wage cuts to move to more stable employment
Brain levels of the neurotoxic pyridinium metabolite HPP+ and extrapyramidal symptoms in haloperidol-treated mice
The typical antipsychotic haloperidol is a highly effective treatment for schizophrenia but its use is limited by a number of serious, and often irreversible, motor side effects. These adverse drug reactions, termed extrapyramidal syndromes (EPS), result from an unknown pathophysiological mechanism. One theory relates to the observation that the haloperidol metabolite HPP+ (4-(4-chlorophenyl)-1-[4-(4-fluorophenyl)-4-oxobutyl]-pyridinium) is structurally similar to MPP+ (1-methyl-4-phenylpyridinium), a neurotoxin responsible for an irreversible neurodegenerative condition similar to Parkinson's disease. To determine whether HPP+ contributes to haloperidol-induced EPS, we measured brain HPP+ and haloperidol levels in strains of mice at high (C57BL/6J and NZO/HILtJ) and low (BALB/cByJ and PWK/PhJ) liability to haloperidol-induced EPS following chronic treatment (7–10 adult male mice per strain). Brain levels of HPP+ and the ratio of HPP+ to haloperidol were not significantly different between the haloperidol-sensitive and haloperidol-resistant strain groups (P = 0.50). Within each group, however, strain differences were seen (P < 0.01), indicating that genetic variation regulating steady-state HPP+ levels exists. Since the HPP+ levels that we observed in mouse brain overlap the range of those detected in post-mortem human brains following chronic haloperidol treatment, the findings from this study are physiologically relevant to humans. The results suggest that strain differences in steady-state HPP+ levels do not explain sensitivity to haloperidol-induced EPS in the mice we studied
SIC-8000 versus hetastarch as a submucosal injection fluid for endoscopic mucosal resection: a randomized controlled trial
Background and Aims
Viscous solutions provide a superior submucosal cushion for endoscopic mucosal resection (EMR). SIC-8000 (Eleview, Aries Pharmaceuticals, La Jolla, Calif) is a commercially available FDA approved solution but hetastarch is also advocated. We performed a randomized trial comparing SIC-8000 to hetastarch as submucosal injection agents for colorectal EMR.
Methods
This was a single-center double-blinded randomized controlled trial performed at a tertiary referral center. Patients were referred to our center with flat or sessile lesions measuring ≥15 mm in size. The primary outcome measures were the Sydney Resection Quotient (SRQ) and the rate of en bloc resections. Secondary outcomes were total volume needed for a sufficient lift, number of resected pieces, and adverse events.
Results
There were 158 patients with 159 adenomas (84 SIC-8000 and 75 hetastarch) and 57 serrated lesions (30 SIC-8000 and 27 hetastarch). SRQ was significantly better in the SIC-8000 group compared with hetastarch group (9.3 vs 8.1, p=0.001). There was no difference in the proportion of lesions with en bloc resections. The total volume of injectate was significantly lower with SIC-8000 (14.8 mL vs 20.6 mL, p=0.038)
Conclusions
SIC-8000 is superior to hetastarch for use during EMR in terms of SRQ and total volume needed, although the absolute differences were small
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