2,486 research outputs found
Optical conductivity with holographic lattices
We add a gravitational background lattice to the simplest holographic model
of matter at finite density and calculate the optical conductivity. With the
lattice, the zero frequency delta function found in previous calculations
(resulting from translation invariance) is broadened and the DC conductivity is
finite. The optical conductivity exhibits a Drude peak with a cross-over to
power-law behavior at higher frequencies. Surprisingly, these results bear a
strong resemblance to the properties of some of the cuprates
Further evidence for lattice-induced scaling
We continue our study of holographic transport in the presence of a
background lattice. We recently found evidence that the presence of a lattice
induces a new intermediate scaling regime in asymptotically spacetimes.
This manifests itself in the optical conductivity which exhibits a robust
power-law dependence on frequency, , in a
"mid-infrared" regime, a result which is in striking agreement with experiments
on the cuprates. Here we provide further evidence for the existence of this
intermediate scaling regime. We demonstrate similar scaling in the
thermoelectric conductivity, find analogous scalings in asymptotically
spacetimes, and show that we get the same results with an ionic lattice
Comparative efficacy and safety of statin and fibrate monotherapy: A systematic review and meta-analysis of head-to-head randomized controlled trials
OBJECTIVE: To assess whether in adults with dyslipidemia, statins reduce cardiovascular events, mortality, and adverse effects when compared to fibrates. METHODS: Systematic review and meta-analysis of head-to-head randomized trials of statin and fibrate monotherapy. MEDLINE, EMBASE, Cochrane, WHO International Controlled Trials Registry Platform, and ClinicalTrials.gov were searched through October 30, 2019. Trials that had a follow-up of at least 28 days, and reported mortality or a cardiovascular outcome of interest were eligible for inclusion. Efficacy outcomes were cardiovascular mortality and major cardiovascular events. Safety outcomes included myalgia, serious adverse effects, elevated serum creatinine, and elevated serum alanine aminotransferase. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using the Mantel-Haenszel fixed-effect model, and heterogeneity was assessed using the I2 statistic. RESULTS: We included 19 eligible trials that directly compared statin and fibrate monotherapy and reported mortality or a cardiovascular event. Studies had a limited duration of follow-up (range 10 weeks to 2 years). We did not find any evidence of a difference between statins and fibrates for cardiovascular mortality (OR 2.35, 95% CI 0.94-5.86, I2 = 0%; ten studies, n = 2657; low certainty), major cardiovascular events (OR 1.15, 95% CI 0.80-1.65, I2 = 13%; 19 studies, n = 7619; low certainty), and myalgia (OR 1.32, 95% CI 0.95-1.83, I2 = 0%; ten studies, n = 6090; low certainty). Statins had less serious adverse effects (OR 0.57, 95% CI 0.36-0.91, I2 = 0%; nine studies, n = 3749; moderate certainty), less elevations in serum creatinine (OR 0.17, 95% CI 0.08-0.36, I2 = 0%; six studies, n = 2553; high certainty), and more elevations in alanine aminotransferase (OR 1.43, 95% CI 1.03-1.99, I2 = 44%; seven studies, n = 5225; low certainty). CONCLUSIONS: The eligible randomized trials of statins versus fibrates were designed to assess short-term lipid outcomes, making it difficult to have certainty about the direct comparative effect on cardiovascular outcomes and mortality. With the exception of myalgia, use of a statin appeared to have a lower incidence of adverse effects compared to use of a fibrate
Consistency-based Semi-supervised Active Learning: Towards Minimizing Labeling Cost
Active learning (AL) combines data labeling and model training to minimize
the labeling cost by prioritizing the selection of high value data that can
best improve model performance. In pool-based active learning, accessible
unlabeled data are not used for model training in most conventional methods.
Here, we propose to unify unlabeled sample selection and model training towards
minimizing labeling cost, and make two contributions towards that end. First,
we exploit both labeled and unlabeled data using semi-supervised learning (SSL)
to distill information from unlabeled data during the training stage. Second,
we propose a consistency-based sample selection metric that is coherent with
the training objective such that the selected samples are effective at
improving model performance. We conduct extensive experiments on image
classification tasks. The experimental results on CIFAR-10, CIFAR-100 and
ImageNet demonstrate the superior performance of our proposed method with
limited labeled data, compared to the existing methods and the alternative AL
and SSL combinations. Additionally, we study an important yet under-explored
problem -- "When can we start learning-based AL selection?". We propose a
measure that is empirically correlated with the AL target loss and is
potentially useful for determining the proper starting point of learning-based
AL methods.Comment: Accepted by ECCV202
A Local Region of Interest Imaging Method for Electrical Impedance Tomography with Internal Electrodes
Electrical Impedance Tomography (EIT) is a very attractive functional imaging method despite the low sensitivity and resolution. The use of internal electrodes with the conventional reconstruction algorithms was not enough to enhance image resolution and accuracy in the region of interest (ROI). We propose a local ROI imaging method with internal electrodes developed from careful analysis of the sensitivity matrix that is designed to reduce the sensitivity of the voxels outside the local region and optimize the sensitivity of the voxel inside the local region. We perform numerical simulations and physical measurements to demonstrate the localized EIT imaging method. In preliminary results with multiple objects we show the benefits of using an internal electrode and the improved resolution due to the local ROI image reconstruction method. The sensitivity is further increased by allowing the surface electrodes to be unevenly spaced with a higher density of surface electrodes near the ROI. Also, we analyse how much the image quality is improved using several performance parameters for comparison. While these have not yet been studied in depth, it convincingly shows an improvement in local sensitivity in images obtained with an internal electrode in comparison to a standard reconstruction method
Detection of the Upper Airway Obstruction using Electrical Impedance Tomography
Obstructive sleep apnea (OSA) is caused by the occlusion of the upper airway. No real-time imaging technique, which can detect such occlusion during natural sleep, exists at the moment. The surface electrodes were attached on the face and neck, and then changes in the conductivity image of the upper airway were successfully detected
Preferred reporting items for studies mapping onto preference-based outcome measures: The MAPS statement
'Mapping' onto generic preference-based outcome measures is increasingly being used as a means of generating health utilities for use within health economic evaluations. Despite publication of technical guides for the conduct of mapping research, guidance for the reporting of mapping studies is currently lacking. The MAPS (MApping onto Preference-based measures reporting Standards) statement is a new checklist, which aims to promote complete and transparent reporting of mapping studies. The primary audiences for the MAPS statement are researchers reporting mapping studies, the funders of the research, and peer reviewers and editors involved in assessing mapping studies for publication. A de novo list of 29 candidate reporting items and accompanying explanations was created by a working group comprised of six health economists and one Delphi methodologist. Following a two-round, modified Delphi survey with representatives from academia, consultancy, health technology assessment agencies and the biomedical journal editorial community, a final set of 23 items deemed essential for transparent reporting, and accompanying explanations, was developed. The items are contained in a user friendly 23 item checklist. They are presented numerically and categorised within six sections, namely: (i) title and abstract; (ii) introduction; (iii) methods; (iv) results; (v) discussion; and (vi) other. The MAPS statement is best applied in conjunction with the accompanying MAPS explanation and elaboration document. It is anticipated that the MAPS statement will improve the clarity, transparency and completeness of reporting of mapping studies. To facilitate dissemination and uptake, the MAPS statement is being co-published by eight health economics and quality of life journals, and broader endorsement is encouraged. The MAPS working group plans to assess the need for an update of the reporting checklist in five years' time. This statement was published jointly in Applied Health Economics and Health Policy, Health and Quality of Life Outcomes, International Journal of Technology Assessment in Health Care, Journal of Medical Economics, Medical Decision Making, PharmacoEconomics, and Quality of Life Research
Continuous non-destructive conductivity monitoring of chondrogenesis using bioimpedance tensor probe
A continuous non-destructive monitoring method is required to apply proper feedback controls during chondrogenesis. We measured the apparent conductivity and the amount of anisotropy on the top and bottom surfaces of samples in the chondrogenesis process to evaluate the ECM structure and composition changes. We compared them with histological trait to analyse the results
Real-time monitoring of tissue property in a liver phantom using an internal electrode and weighted frequency difference conductivity during microwave ablation
We measured the time difference and weighted frequency difference conductivity images to monitor the changes of temperature and tissue property in a liver phantom due to the microwave ablation. Pixels in regions of interest were compared between conventional boundary surface electrode method and focused configuration with an internal electrode
Does implementation matter if comprehension is lacking? A qualitative investigation into perceptions of advance care planning in people with cancer
Purpose: While advance care planning holds promise, uptake is variable and it is unclear how well people engage with or comprehend advance care planning. The objective of this study was to explore how people with cancer comprehended Advance Care Plans and examine how accurately advance care planning documentation represented patient wishes.
Methods: This study used a qualitative descriptive design. Data collection comprised interviews and an examination of participants’ existing advance care planning documentation. Participants included those who had any diagnosis of cancer with an advance care plan recorded: Refusal of Treatment Certificate; Statement of Choices; and/or Enduring Power of Attorney (Medical Treatment) at one cancer treatment centre.
Results: Fourteen participants were involved in the study. Twelve participants were female (86%). The mean age was 77 (range: 61-91) and participants had completed their advance care planning documentation between 8 and 72 weeks prior to the interview (mean 33 weeks). Three themes were evident from the data: Incomplete advance care planning understanding and confidence; Limited congruence for attitude and documentation; Advance care planning can enable peace of mind. Complete advance care planning understanding was unusual; most participants demonstrated partial comprehension of their own advance care plan, and some indicated very limited understanding. Participants’ attitudes and their written document congruence was limited, but advance care planning was seen as helpful.
Conclusions: This study highlighted advance care planning was not a completely accurate representation of patient wishes. There is opportunity to improve how patients comprehend their own advance care planning documentation
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