1,838 research outputs found
Matter-positronium interaction: An exact diagonalization study of the He atom - positronium system
The many-body system comprising a He nucleus, three electrons, and a positron
has been studied using the exact diagonalization technique. The purpose has
been to clarify to which extent the system can be considered as a
distinguishable positronium (Ps) atom interacting with a He atom and, thereby,
to pave the way to a practical atomistic modeling of Ps states and annihilation
in matter. The maximum value of the distance between the positron and the
nucleus is constrained and the Ps atom at different distances from the nucleus
is identified from the electron and positron densities, as well as from the
electron-positron distance and center-of-mass distributions. The polarization
of the Ps atom increases as its distance from the nucleus decreases. A
depletion of the He electron density, particularly large at low density values,
has been observed. The ortho-Ps pick-off annihilation rate calculated as the
overlap of the positron and the free He electron densities has to be corrected
for the observed depletion, specially at large pores/voids.Comment: 18 pages, 8 figure
Toward an Energy Efficient Language and Compiler for (Partially) Reversible Algorithms
We introduce a new programming language for expressing reversibility,
Energy-Efficient Language (Eel), geared toward algorithm design and
implementation. Eel is the first language to take advantage of a partially
reversible computation model, where programs can be composed of both reversible
and irreversible operations. In this model, irreversible operations cost energy
for every bit of information created or destroyed. To handle programs of
varying degrees of reversibility, Eel supports a log stack to automatically
trade energy costs for space costs, and introduces many powerful control logic
operators including protected conditional, general conditional, protected
loops, and general loops. In this paper, we present the design and compiler for
the three language levels of Eel along with an interpreter to simulate and
annotate incurred energy costs of a program.Comment: 17 pages, 0 additional figures, pre-print to be published in The 8th
Conference on Reversible Computing (RC2016
Comparing the plug-in gait model output to an individually scaled musculoskeletal model using an extensive normative data set
Photonic crystal resonator integrated in a microfluidic system
We report on a novel optofluidic system consisting of a silica-based 1D
photonic crystal, integrated planar waveguides and electrically insulated
fluidic channels. An array of pillars in a microfluidic channel designed for
electrochromatography is used as a resonator for on-column label-free
refractive index detection. The resonator was fabricated in a silicon
oxynitride platform, to support electroosmotic flow, and operated at 1.55
microns. Different aqueous solutions of ethanol with refractive indices ranging
from n = 1.3330 to 1.3616 were pumped into the column/resonator and the
transmission spectra were recorded. Linear shifts of the resonant wavelengths
yielded a maximum sensitivity of 480 nm/RIU and a minimum difference of 0.007
RIU was measured
The Mars Science Laboratory Organic Check Material
The Organic Check Material (OCM) has been developed for use on the Mars Science Laboratory mission to serve as a sample standard for verification of organic cleanliness and characterization of potential sample alteration as a function of the sample acquisition and portioning process on the Curiosity rover. OCM samples will be acquired using the same procedures for drilling, portioning and delivery as are used to study martian samples with The Sample Analysis at Mars (SAM) instrument suite during MSL surface operations. Because the SAM suite is highly sensitive to organic molecules, the mission can better verify the cleanliness of Curiosity's sample acquisition hardware if a known material can be processed through SAM and compared with the results obtained from martian samples
Evaluation of the influence of kyphosis and scoliosis on intervertebral disc extrusion in French bulldogs
Although thoracic vertebral malformations with kyphosis and scoliosis are often considered incidental findings on diagnostic imaging studies of screw-tailed brachycephalic breeds, they have been suggested to interfere with spinal biomechanics and intervertebral disc degeneration. It is however unknown if an abnormal spinal curvature also predisposes dogs to develop clinically relevant intervertebral disc herniations. The aim of this study was to evaluate if the occurrence of thoracic vertebral malformations, kyphosis or scoliosis would be associated with a higher prevalence of cervical or thoracolumbar intervertebral disc extrusion in French bulldogs
Follow-up of blood-pressure lowering and glucose control in type 2 diabetes.
BACKGROUND
In the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) factorial trial, the combination of perindopril and indapamide reduced mortality among patients with type 2 diabetes, but intensive glucose control, targeting a glycated hemoglobin level of less than 6.5%, did not. We now report results of the 6-year post-trial follow-up.
METHODS
We invited surviving participants, who had previously been assigned to perindopril–indapamide or placebo and to intensive or standard glucose control (with the glucose-control comparison extending for an additional 6 months), to participate in a post-trial follow-up evaluation. The primary end points were death from any cause and major macrovascular events.
RESULTS
The baseline characteristics were similar among the 11,140 patients who originally underwent randomization and the 8494 patients who participated in the post-trial follow-up for a median of 5.9 years (blood-pressure–lowering comparison) or 5.4 years (glucose-control comparison). Between-group differences in blood pressure and glycated hemoglobin levels during the trial were no longer evident by the first post-trial visit. The reductions in the risk of death from any cause and of death from cardiovascular causes that had been observed in the group receiving active blood-pressure–lowering treatment during the trial were attenuated but significant at the end of the post-trial follow-up; the hazard ratios were 0.91 (95% confidence interval [CI], 0.84 to 0.99; P=0.03) and 0.88 (95% CI, 0.77 to 0.99; P=0.04), respectively. No differences were observed during follow-up in the risk of death from any cause or major macrovascular events between the intensive-glucose-control group and the standard-glucose-control group; the hazard ratios were 1.00 (95% CI, 0.92 to 1.08) and 1.00 (95% CI, 0.92 to 1.08), respectively.
CONCLUSIONS
The benefits with respect to mortality that had been observed among patients originally assigned to blood-pressure–lowering therapy were attenuated but still evident at the end of follow-up. There was no evidence that intensive glucose control during the trial led to long-term benefits with respect to mortality or macrovascular events
2021 international consensus statement on optical coherence tomography for basal cell carcinoma: image characteristics, terminology and educational needs
Background Despite the widespread use of optical coherence tomography (OCT) for imaging of keratinocyte carcinoma, we lack an expert consensus on the characteristic OCT features of basal cell carcinoma (BCC), an internationally vetted set of OCT terms to describe various BCC subtypes, and an educational needs assessment. Objectives To identify relevant BCC features in OCT images, propose terminology based on inputs from an expert panel and identify content for a BCC-specific curriculum for OCT trainees. Methods Over three rounds, we conducted a Delphi consensus study on BCC features and terminology between March and September 2020. In the first round, experts were asked to propose BCC subtypes discriminable by OCT, provide OCT image features for each proposed BCC subtypes and suggest content for a BCC-specific OCT training curriculum. If agreement on a BCC-OCT feature exceeded 67%, the feature was accepted and included in a final review. In the second round, experts had to re-evaluate features with less than 67% agreement and rank the ten most relevant BCC OCT image features for superficial BCC, nodular BCC and infiltrative and morpheaphorm BCC subtypes. In the final round, experts received the OCT-BCC consensus list for a final review, comments and confirmation. Results The Delphi included six key opinion leaders and 22 experts. Consensus was found on terminology for three OCT BCC image features: (i) hyporeflective areas, (ii) hyperreflective areas and (iii) ovoid structures. Further, the participants ranked the ten most relevant image features for nodular, superficial, infiltrative and morpheaform BCC. The target group and the key components for a curriculum for OCT imaging of BCC have been defined. Conclusion We have established a set of OCT image features for BCC and preferred terminology. A comprehensive curriculum based on the expert suggestions will help implement OCT imaging of BCC in clinical and research settings
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