152 research outputs found
A Mixed Eulerian-Lagrangian Model for the Analysis of Dynamic Fracture
National Science Foundation Grant MEA 84-0065
Droplet migration: quantitative comparisons with experiment
An important practical feature of simulating droplet migration computationally,
using the lubrication approach coupled to a disjoining pressure term, is
the need to specify the thickness, H, of a thin energetically stable wetting layer,
or precursor lm, over the entire substrate. The necessity that H be small in
order to improve the accuracy of predicted droplet migration speeds, allied to the
need for mesh resolution of the same order as H near wetting lines, increases the
computational demands signicantly. To date no systematic investigation of these
requirements on the quantitative agreement between prediction and experimental
observation has been reported. Accordingly, this paper combines highly ecient
Multigrid methods for solving the associated lubrication equations with a parallel
computing framework, to explore the eect of H and mesh resolution. The solutions
generated are compared with recent experimentally determined migration
speeds for droplet
ows down an inclined plane
Bone mineral density and risk of heart failure in older adults: The Cardiovascular Health Study
Background
Despite increasing evidence of a common link between bone and heart health, the relationship between bone mineral density (
BMD
) and heart failure (
HF
) risk remains insufficiently studied.
Methods and Results
We investigated whether
BMD
measured by dual‐energy x‐ray absorptiometry was associated with incident
HF
in an older cohort. Cox models were stratified by sex and interactions of
BMD
with race assessed.
BMD
was examined at the total hip and femoral neck separately, both continuously and by World Health Organization categories. Of 1250 participants, 442 (55% women) developed
HF
during the median follow‐up of 10.5 years. In both black and nonblack women, neither total hip nor femoral neck
BMD
was significantly associated with
HF
; there was no significant interaction by race. In black and nonblack men, total hip, but not femoral neck,
BMD
was significantly associated with
HF
, with evidence of an interaction by race. In nonblack men, lower total hip
BMD
was associated with higher
HF
risk (hazard ratio, 1.13 [95% CI, 1.01–1.26] per 0.1 g/cm
2
decrement), whereas in black men, lower total hip
BMD
was associated with lower
HF
risk (hazard ratio, 0.74 [95% CI, 0.59–0.94]). There were no black men with total hip osteoporosis. Among nonblack men, total hip osteoporosis was associated with higher
HF
risk (hazard ratio, 2.83 [95% CI, 1.39–5.74]) compared with normal
BMD
.
Conclusions
Among older adults, lower total hip
BMD
was associated with higher
HF
risk in nonblack men but lower risk in black men, with no evidence of an association in women. Further research is needed to replicate these findings and to study potential underlying pathways.
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Non-Minimal Sneutrino Inflation, Peccei-Quinn Phase Transition and non-Thermal Leptogenesis
We consider a phenomenological extension of the minimal supersymmetric
standard model which incorporates non-minimal chaotic inflation, driven by a
quartic potential associated with the lightest right-handed sneutrino.
Inflation is followed by a Peccei-Quinn phase transition based on
renormalizable superpotential terms, which resolves the strong CP and mu
problems of the minimal supersymmetric standard model provided that one related
parameter of the superpotential is somewhat small. Baryogenesis occurs via
non-thermal leptogenesis, which is realized by the inflaton decay. Confronting
our scenario with the current observational data on the inflationary
observables, the baryon assymetry of the universe, the gravitino limit on the
reheating temperature and the upper bound on the light neutrino masses, we
constrain the effective Yukawa coupling involved in the decay of the inflaton
to relatively small values and the inflaton mass to values lower than 10^12
GeV.Comment: 21 pages including 3 figures; Final versio
Postoperative complications after procedure for prolapsed hemorrhoids (PPH) and stapled transanal rectal resection (STARR) procedures
Procedure for prolapsing hemorrhoids (PPH) and stapled transanal rectal resection for obstructed defecation (STARR) carry low postoperative pain, but may be followed by unusual and severe postoperative complications. This review deals with the pathogenesis, prevention and treatment of adverse events that may occasionally be life threatening. PPH and STARR carry the expected morbidity following anorectal surgery, such as bleeding, strictures and fecal incontinence. Complications that are particular to these stapled procedures are rectovaginal fistula, chronic proctalgia, total rectal obliteration, rectal wall hematoma and perforation with pelvic sepsis often requiring a diverting stoma. A higher complication rate and worse results are expected after PPH for fourth-degree piles. Enterocele and anismus are contraindications to PPH and STARR and both operations should be used with caution in patients with weak sphincters. In conclusion, complications after PPH and STARR are not infrequent and may be difficult to manage. However, if performed in selected cases by skilled specialists aware of the risks and associated diseases, some complications may be prevented
Characteristics of Early-Onset vs Late-Onset Colorectal Cancer: A Review.
The incidence of early-onset colorectal cancer (younger than 50 years) is rising globally, the reasons for which are unclear. It appears to represent a unique disease process with different clinical, pathological, and molecular characteristics compared with late-onset colorectal cancer. Data on oncological outcomes are limited, and sensitivity to conventional neoadjuvant and adjuvant therapy regimens appear to be unknown. The purpose of this review is to summarize the available literature on early-onset colorectal cancer.
Within the next decade, it is estimated that 1 in 10 colon cancers and 1 in 4 rectal cancers will be diagnosed in adults younger than 50 years. Potential risk factors include a Westernized diet, obesity, antibiotic usage, and alterations in the gut microbiome. Although genetic predisposition plays a role, most cases are sporadic. The full spectrum of germline and somatic sequence variations implicated remains unknown. Younger patients typically present with descending colonic or rectal cancer, advanced disease stage, and unfavorable histopathological features. Despite being more likely to receive neoadjuvant and adjuvant therapy, patients with early-onset disease demonstrate comparable oncological outcomes with their older counterparts.
The clinicopathological features, underlying molecular profiles, and drivers of early-onset colorectal cancer differ from those of late-onset disease. Standardized, age-specific preventive, screening, diagnostic, and therapeutic strategies are required to optimize outcomes
Multi-ancestry study of blood lipid levels identifies four loci interacting with physical activity
Many genetic loci affect circulating lipid levels, but it remains unknown whether lifestyle factors, such as physical activity, modify these genetic effects. To identify lipid loci interacting with physical activity, we performed genome-wide analyses of circulating HDL cholesterol, LDL cholesterol, and triglyceride levels in up to 120,979 individuals of European, African, Asian, Hispanic, and Brazilian ancestry, with follow-up of suggestive associations in an additional 131,012 individuals. We find four loci, in/near CLASP1, LHX1, SNTA1, and CNTNAP2, that are associated with circulating lipid levels through interaction with physical activity; higher levels of physical activity enhance the HDL cholesterol-increasing effects of the CLASP1, LHX1, and SNTA1 loci and attenuate the LDL cholesterol- increasing effect of the CNTNAP2 locus. The CLASP1, LHX1, and SNTA1 regions harbor genes linked to muscle function and lipid metabolism. Our results elucidate the role of physical activity interactions in the genetic contribution to blood lipid levels
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