3,994 research outputs found
Direct observation of active material concentration gradients and crystallinity breakdown in LiFePO4 electrodes during charge/discharge cycling of lithium batteries
The phase changes that occur during discharge of an electrode comprised of LiFePO4, carbon, and PTFE binder have been studied in lithium half cells by using X-ray diffraction measurements in reflection geometry. Differences in the state of charge between the front and the back of LiFePO4 electrodes have been visualized. By modifying the X-ray incident angle the depth of penetration of the X-ray beam into the electrode was altered, allowing for the examination of any concentration gradients that were present within the electrode. At high rates of discharge the electrode side facing the current collector underwent limited lithium insertion while the electrode as a whole underwent greater than 50% of discharge. This behavior is consistent with depletion at high rate of the lithium content of the electrolyte contained in the electrode pores. Increases in the diffraction peak widths indicated a breakdown of crystallinity within the active material during cycling even during the relatively short duration of these experiments, which can also be linked to cycling at high rate
Analytic Controllability of Time-Dependent Quantum Control Systems
The question of controllability is investigated for a quantum control system
in which the Hamiltonian operator components carry explicit time dependence
which is not under the control of an external agent. We consider the general
situation in which the state moves in an infinite-dimensional Hilbert space, a
drift term is present, and the operators driving the state evolution may be
unbounded. However, considerations are restricted by the assumption that there
exists an analytic domain, dense in the state space, on which solutions of the
controlled Schrodinger equation may be expressed globally in exponential form.
The issue of controllability then naturally focuses on the ability to steer the
quantum state on a finite-dimensional submanifold of the unit sphere in Hilbert
space -- and thus on analytic controllability. A relatively straightforward
strategy allows the extension of Lie-algebraic conditions for strong analytic
controllability derived earlier for the simpler, time-independent system in
which the drift Hamiltonian and the interaction Hamiltonia have no intrinsic
time dependence. Enlarging the state space by one dimension corresponding to
the time variable, we construct an augmented control system that can be treated
as time-independent. Methods developed by Kunita can then be implemented to
establish controllability conditions for the one-dimension-reduced system
defined by the original time-dependent Schrodinger control problem. The
applicability of the resulting theorem is illustrated with selected examples.Comment: 13 page
Association of flavonoids and flavonoid-rich foods with all-cause mortality: The Blue Mountains Eye Study
BACKGROUND: Higher intakes of flavonoids provide health benefits, however, the importance of each flavonoid class and which population groups may receive the greatest protection from higher flavonoid intake warrants further investigation.
OBJECTIVE: To explore the associations of flavonoid and flavonoid-rich wholefood intakes with all-cause mortality and the moderating effects of early mortality risk factors.
DESIGN: The study included 2349 participants of The Blue Mountains Eye Study, with a mean ± SD age at baseline of 64.7 ± 9.2 years. Flavonoid intake was calculated from baseline food frequency questionnaires using US Department of Agriculture food composition databases. Associations were examined using adjusted Cox proportional hazards models.
RESULTS: After 14 years of follow-up, 677 participants died. There was a flavonoid threshold effect with the greatest risk reduction seen between low and moderate intakes of total flavonoids, flavonoid classes and flavonoid-rich foods. Amongst the whole cohort, participants in the highest tertile of anthocyanidin intake had a significantly lower risk of all-cause mortality [multivariable adjusted HR (95%CI): 0.76 (0.61, 0.94)] when compared to those in the lowest tertile. Amongst participants with at least one early mortality risk factor (smoking, high alcohol consumption, no regular exercise or obesity), risk of all-cause mortality was lower in those in the highest intake tertile for total flavonoids [adjusted HR: 0.77 (0.59, 1.00)], flavan-3-ols [0.75 (0.58, 0.98)], anthocyanidins [0.70 (0.54, 0.92)], and proanthocyanidins [0.69 (0.52, 0.92)], compared to those in the lowest tertile. No similar associations were observed among those without any risk factors. Similarly, consumption of apples, tea and the individual flavonoid compounds, quercetin and epicatechin, were associated with a lower risk of all-cause mortality among participants with at least one risk factor, but not amongst other participants.
CONCLUSION: Moderate to high intakes of flavonoids and certain flavonoid subclasses may provide health benefits, particularly for individuals with at least one early mortality risk factor
Model organisms contribute to diagnosis and discovery in the Undiagnosed Diseases Network: Current state and a future vision
Decreased sequencing costs have led to an explosion of genetic and genomic data. These data have revealed thousands of candidate human disease variants. Establishing which variants cause phenotypes and diseases, however, has remained challenging. Significant progress has been made, including advances by the National Institutes of Health (NIH)-funded Undiagnosed Diseases Network (UDN). However, 6000-13,000 additional disease genes remain to be identified. The continued discovery of rare diseases and their genetic underpinnings provides benefits to affected patients, of whom there are more than 400 million worldwide, and also advances understanding the mechanisms of more common diseases. Platforms employing model organisms enable discovery of novel gene-disease relationships, help establish variant pathogenicity, and often lead to the exploration of underlying mechanisms of pathophysiology that suggest new therapies. The Model Organism Screening Center (MOSC) of the UDN is a unique resource dedicated to utilizing informatics and functional studies in model organisms, including worm (Caenorhabditis elegans), fly (Drosophila melanogaster), and zebrafish (Danio rerio), to aid in diagnosis. The MOSC has directly contributed to the diagnosis of challenging cases, including multiple patients with complex, multi-organ phenotypes. In addition, the MOSC provides a framework for how basic scientists and clinicians can collaborate to drive diagnoses. Customized experimental plans take into account patient presentations, specific genes and variant(s), and appropriateness of each model organism for analysis. The MOSC also generates bioinformatic and experimental tools and reagents for the wider scientific community. Two elements of the MOSC that have been instrumental in its success are (1) multidisciplinary teams with expertise in variant bioinformatics and in human and model organism genetics, and (2) mechanisms for ongoing communication with clinical teams. Here we provide a position statement regarding the central role of model organisms for continued discovery of disease genes, and we advocate for the continuation and expansion of MOSC-type research entities as a Model Organisms Network (MON) to be funded through grant applications submitted to the NIH, family groups focused on specific rare diseases, other philanthropic organizations, industry partnerships, and other sources of support
Endoscopic and Nonendoscopic Approaches to Single-Level Lumbar Spine Decompression: Propensity Score-Matched Comparative Analysis and Frailty-Driven Predictive Model
Objective The endoscopic spine surgery (ESS) approach is associated with high levels of patient satisfaction, shorter recovery time, and reduced complications. The present study reports multicenter, international data, comparing ESS and non-ESS approaches for single-level lumbar decompression, and proposes a frailty-driven predictive model for nonhome discharge (NHD) disposition. Methods Cases of ESS and non-ESS lumbar spine decompression were queried from the American College of Surgeons National Surgical Quality Improvement Program database (2017–2020). Propensity score matching was performed on baseline characteristics frailty score (measured by risk analysis index [RAI] and modified frailty index-5 [mFI-5]). The primary outcome of interest was NHD disposition. A predictive model was built using logistic regression with RAI as the primary driver. Results Single-level nonfusion spine lumbar decompression surgery was performed in 38,686 patients. Frailty, as measured by RAI, was a reliable predictor of NHD with excellent discriminatory accuracy in receiver operating characteristic (ROC) curve analysis: C-statistic: 0.80 (95% confidence interval [CI], 0.65–0.94) in ESS cohort, C-statistic: 0.75 (95% CI, 0.73–0.76) overall cohort. After propensity score matching, there was a reduction in total operative time (89 minutes vs. 103 minutes, p = 0.049) and hospital length of stay (LOS) (0.82 days vs. 1.37 days, p < 0.001) in patients treated endoscopically. In ROC curve analysis, the frailty-driven predictive model performed with excellent diagnostic accuracy for the primary outcome of NHD (C-statistic: 0.87; 95% CI, 0.85–0.88). Conclusion After frailty-based propensity matching, ESS is associated with reduced operative time, shorter hospital LOS, and decreased NHD. The RAI frailty-driven model predicts NHD with excellent diagnostic accuracy and may be applied to preoperative decision-making with a user-friendly calculator: nsgyfrailtyoutcomeslab.shinyapps.io/lumbar_decompression_dischargedispo
Phenoloxidase activity acts as a mosquito innate immune response against infection with semliki forest virus
Several components of the mosquito immune system including the RNA interference (RNAi), JAK/STAT, Toll and IMD pathways have previously been implicated in controlling arbovirus infections. In contrast, the role of the phenoloxidase (PO) cascade in mosquito antiviral immunity is unknown. Here we show that conditioned medium from the Aedes albopictus-derived U4.4 cell line contains a functional PO cascade, which is activated by the bacterium Escherichia coli and the arbovirus Semliki Forest virus (SFV) (Togaviridae; Alphavirus). Production of recombinant SFV expressing the PO cascade inhibitor Egf1.0 blocked PO activity in U4.4 cell- conditioned medium, which resulted in enhanced spread of SFV. Infection of adult female Aedes aegypti by feeding mosquitoes a bloodmeal containing Egf1.0-expressing SFV increased virus replication and mosquito mortality. Collectively, these results suggest the PO cascade of mosquitoes plays an important role in immune defence against arboviruses
Evolution with hole doping of the electronic excitation spectrum in the cuprate superconductors
The recent scanning tunnelling results of Alldredge et al on Bi-2212 and of
Hanaguri et al on Na-CCOC are examined from the perspective of the BCS/BEC
boson-fermion resonant crossover model for the mixed-valent HTSC cuprates. The
model specifies the two energy scales controlling the development of HTSC
behaviour and the dichotomy often now alluded to between nodal and antinodal
phenomena in the HTSC cuprates. Indication is extracted from the data as to how
the choice of the particular HTSC system sees these two basic energy scales
(cursive-U, the local pair binding energy and, Delta-sc, the nodal BCS-like gap
parameter) evolve with doping and change in degree of metallization of the
structurally and electronically perturbed mixed-valent environment.Comment: 19 pages, 5 figure
Personalization Paradox in Behavior Change Apps:Lessons from a Social Comparison-Based Personalized App for Physical Activity
Social comparison-based features are widely used in social computing apps.
However, most existing apps are not grounded in social comparison theories and
do not consider individual differences in social comparison preferences and
reactions. This paper is among the first to automatically personalize social
comparison targets. In the context of an m-health app for physical activity, we
use artificial intelligence (AI) techniques of multi-armed bandits. Results
from our user study (n=53) indicate that there is some evidence that motivation
can be increased using the AI-based personalization of social comparison. The
detected effects achieved small-to-moderate effect sizes, illustrating the
real-world implications of the intervention for enhancing motivation and
physical activity. In addition to design implications for social comparison
features in social apps, this paper identified the personalization paradox, the
conflict between user modeling and adaptation, as a key design challenge of
personalized applications for behavior change. Additionally, we propose
research directions to mitigate this Personalization Paradox
Evolutionary relationships among barley and <i>Arabidopsis</i> core circadian clock and clock-associated genes
The circadian clock regulates a multitude of plant developmental and metabolic processes. In crop species, it contributes significantly to plant performance and productivity and to the adaptation and geographical range over which crops can be grown. To understand the clock in barley and how it relates to the components in the Arabidopsis thaliana clock, we have performed a systematic analysis of core circadian clock and clock-associated genes in barley, Arabidopsis and another eight species including tomato, potato, a range of monocotyledonous species and the moss, Physcomitrella patens. We have identified orthologues and paralogues of Arabidopsis genes which are conserved in all species, monocot/dicot differences, species-specific differences and variation in gene copy number (e.g. gene duplications among the various species). We propose that the common ancestor of barley and Arabidopsis had two-thirds of the key clock components identified in Arabidopsis prior to the separation of the monocot/dicot groups. After this separation, multiple independent gene duplication events took place in both monocot and dicot ancestors. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00239-015-9665-0) contains supplementary material, which is available to authorized users
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Biological, clinical and population relevance of 95 loci for blood lipids.
Plasma concentrations of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglycerides are among the most important risk factors for coronary artery disease (CAD) and are targets for therapeutic intervention. We screened the genome for common variants associated with plasma lipids in >100,000 individuals of European ancestry. Here we report 95 significantly associated loci (P < 5 x 10(-8)), with 59 showing genome-wide significant association with lipid traits for the first time. The newly reported associations include single nucleotide polymorphisms (SNPs) near known lipid regulators (for example, CYP7A1, NPC1L1 and SCARB1) as well as in scores of loci not previously implicated in lipoprotein metabolism. The 95 loci contribute not only to normal variation in lipid traits but also to extreme lipid phenotypes and have an impact on lipid traits in three non-European populations (East Asians, South Asians and African Americans). Our results identify several novel loci associated with plasma lipids that are also associated with CAD. Finally, we validated three of the novel genes-GALNT2, PPP1R3B and TTC39B-with experiments in mouse models. Taken together, our findings provide the foundation to develop a broader biological understanding of lipoprotein metabolism and to identify new therapeutic opportunities for the prevention of CAD
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