SUMMARY
The interpretation of seismic tomographic images of upper‐mantle seismic wave speed structure is often a matter of considerable debate because the observations can usually be explained by a ...range of hypotheses, including variable temperature, composition, anisotropy, and the presence of partial melt. An additional problem, often overlooked in tomographic studies using relative as opposed to absolute arrival‐times, is the issue of the resulting velocity model’s zero mean. In shield areas, for example, relative arrival‐time analysis strips off a background mean velocity structure that is markedly fast compared to the global average. Conversely, in active areas, the background mean is often markedly slow compared to the global average. Appreciation of this issue is vital when interpreting seismic tomographic images: ‘high’ and ‘low’ velocity anomalies should not necessarily be interpreted, respectively, as ‘fast’ and ‘slow’ compared to ‘normal mantle’. This issue has been discussed in the seismological literature in detail over the years, yet subsequent tomography studies have still fallen into the trap of mis‐interpreting their velocity models. I highlight here some recent examples of this and provide a simple strategy to address the problem using constraints from a recent global tomographic model, and insights from catalogues of absolute traveltime anomalies. Consultation of such absolute measures of seismic wave speed should be routine during regional tomographic studies, if only for the benefit of the broader Earth Science community, who readily follow the red = hot and slow, blue = cold and fast rule of thumb when interpreting the images for themselves.
Background
Demonstrating that the data produced in metabolic phenotyping investigations (metabolomics/metabonomics) is of good quality is increasingly seen as a key factor in gaining acceptance for ...the results of such studies. The use of established quality control (QC) protocols, including appropriate QC samples, is an important and evolving aspect of this process. However, inadequate or incorrect reporting of the QA/QC procedures followed in the study may lead to misinterpretation or overemphasis of the findings and prevent future metanalysis of the body of work.
Objective
The aim of this guidance is to provide researchers with a framework that encourages them to describe quality assessment and quality control procedures and outcomes in mass spectrometry and nuclear magnetic resonance spectroscopy-based methods in untargeted metabolomics, with a focus on reporting on QC samples in sufficient detail for them to be understood, trusted and replicated. There is no intent to be proscriptive with regard to analytical best practices; rather, guidance for
reporting
QA/QC procedures is suggested. A template that can be completed as studies progress to ensure that relevant data is collected, and further documents, are provided as on-line resources.
Key reporting practices
Multiple topics should be considered when reporting QA/QC protocols and outcomes for metabolic phenotyping data. Coverage should include the role(s), sources, types, preparation and uses of the QC materials and samples
generally
employed in the generation of metabolomic data. Details such as sample matrices and sample preparation, the use of test mixtures and system suitability tests, blanks and technique-specific factors are considered and methods for reporting are discussed, including the importance of reporting the acceptance criteria for the QCs. To this end, the reporting of the QC samples and results are considered at two levels of detail: “minimal” and “best reporting practice” levels.
Abstract
This study aimed to characterize peak exercise cardiac function and thigh muscle fatty infiltration and their relationships with VO
2
peak among anthracycline-treated breast cancer survivors ...(BCS). BCS who received anthracycline chemotherapy ~ 1 year earlier (n = 16) and matched controls (matched-CON, n = 16) were enrolled. Resting and peak exercise cardiac function, myocardial T
1
mapping (marker of fibrosis), and thigh muscle fat infiltration were assessed by magnetic resonance imaging, and VO
2
peak by cycle test. Compared to matched-CON, BCS had lower peak SV (64 ± 9 vs 57 ± 10 mL/m
2
, p = 0.038), GLS (− 30.4 ± 2.2 vs − 28.0 ± 2.5%, p = 0.008), and arteriovenous oxygen difference (16.4 ± 3.6 vs 15.2 ± 3.9 mL/100 mL, p = 0.054). Mediation analysis showed: (1) greater myocardial T
1
time (fibrosis) is inversely related to cardiac output and end-systolic volume exercise reserve; (2) greater thigh muscle fatty infiltration is inversely related to arteriovenous oxygen difference; both of which negatively influence VO
2
peak. Peak SV (R
2
= 65%) and thigh muscle fat fraction (R
2
= 68%) were similarly strong independent predictors of VO
2
peak in BCS and matched-CON combined. Post-anthracyclines, myocardial fibrosis is associated with impaired cardiac reserve, and thigh muscle fatty infiltration is associated with impaired oxygen extraction, which both contribute to VO
2
peak.
The calyx of Held Schneggenburger, Ralf; Forsythe, Ian D
Cell and tissue research
326, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The calyx of Held is a large glutamatergic synapse in the mammalian auditory brainstem. By using brain slice preparations, direct patch-clamp recordings can be made from the nerve terminal and its ...postsynaptic target (principal neurons of the medial nucleus of the trapezoid body). Over the last decade, this preparation has been increasingly employed to investigate basic presynaptic mechanisms of transmission in the central nervous system. We review here the background to this preparation and summarise key findings concerning voltage-gated ion channels of the nerve terminal and the ionic mechanisms involved in exocytosis and modulation of transmitter release. The accessibility of this giant terminal has also permitted Ca(2+)-imaging and -uncaging studies combined with electrophysiological recording and capacitance measurements of exocytosis. Together, these studies convey the panopoly of presynaptic regulatory processes underlying the regulation of transmitter release, its modulatory control and short-term plasticity within one identified synaptic terminal.
•Optimal geothermal well placement remains unresolved.•Examine moderate temperature Basal Cambrian Sandstone Formation in Alberta, Canada.•Created geothermal earth model with dimensions 1km x 1km ...(horiz.) x 2.8km vertical.•0.5-6 energy produced to invested ratio depends on well configuration and flow rate.•Two-well configuration achieves better efficiency than five-well configuration.
Geothermal energy harvesting offers a clean option for energy generation with nearly zero greenhouse gas emission. However, due to the lack of understanding of geothermal resource characterization (geological properties and distributions), optimal well placement and operation for energy generation, and energy return on energy invested, geothermal development has been slow. Recently, geothermal energy extraction is drawing attention for its global potential due to environmental concerns about carbon-intensive energy generation from fossil fuels. Here, we examine a potential case of geothermal energy extraction from a sandstone, moderate temperature, low permeability geothermal resource in Central Alberta, Canada, which has not been simulated before. We construct a detailed earth model of dimensions 1,000 m by 1,000 m horizontally and 2,800 m vertically from the surface to the geothermal reservoir using well log data. Heat losses along the wells are taken into account. From detailed geological modelling and thermal reservoir simulation, we demonstrate that different well configurations affect energy extraction from the geothermal resource. The results show that energy produced to energy invested ratio ranges from 1 to 6 GJ/GJ depending on the well configuration, operating rate, and permeability of the reservoir. The outcomes from the research suggest that geothermal development in Alberta will require careful design and operating strategy to yield useful energy returns.
The joint spectral radius of a compact set of d×d matrices is defined to be the maximum possible exponential growth rate of products of matrices drawn from that set. In this article, we investigate ...the ergodic‐theoretic structure of those sequences of matrices drawn from a given set whose products grow at the maximum possible rate. This leads to a notion of Mather set for matrix sequences, which is analogous to the Mather set in Lagrangian dynamics. We prove a structure theorem establishing the general properties of these Mather sets and describing the extent to which they characterise matrix sequences of maximum growth. We give applications of this theorem to the study of joint spectral radii and to the stability theory of discrete linear inclusions.
These results rest on some general theorems on the structure of orbits of maximum growth for subadditive observations of dynamical systems, including an extension of the semiuniform subadditive ergodic theorem of Schreiber, Sturman and Stark, and an extension of a noted lemma of Y. Peres. These theorems are presented in the appendix.
The long-term effects of sibutramine treatment on the rates of cardiovascular events and cardiovascular death among subjects at high cardiovascular risk have not been established.
We enrolled in our ...study 10,744 overweight or obese subjects, 55 years of age or older, with preexisting cardiovascular disease, type 2 diabetes mellitus, or both to assess the cardiovascular consequences of weight management with and without sibutramine in subjects at high risk for cardiovascular events. All the subjects received sibutramine in addition to participating in a weight-management program during a 6-week, single-blind, lead-in period, after which 9804 subjects underwent random assignment in a double-blind fashion to sibutramine (4906 subjects) or placebo (4898 subjects). The primary end point was the time from randomization to the first occurrence of a primary outcome event (nonfatal myocardial infarction, nonfatal stroke, resuscitation after cardiac arrest, or cardiovascular death).
The mean duration of treatment was 3.4 years. The mean weight loss during the lead-in period was 2.6 kg; after randomization, the subjects in the sibutramine group achieved and maintained further weight reduction (mean, 1.7 kg). The mean blood pressure decreased in both groups, with greater reductions in the placebo group than in the sibutramine group (mean difference, 1.2/1.4 mm Hg). The risk of a primary outcome event was 11.4% in the sibutramine group as compared with 10.0% in the placebo group (hazard ratio, 1.16; 95% confidence interval CI, 1.03 to 1.31; P=0.02). The rates of nonfatal myocardial infarction and nonfatal stroke were 4.1% and 2.6% in the sibutramine group and 3.2% and 1.9% in the placebo group, respectively (hazard ratio for nonfatal myocardial infarction, 1.28; 95% CI, 1.04 to 1.57; P=0.02; hazard ratio for nonfatal stroke, 1.36; 95% CI, 1.04 to 1.77; P=0.03). The rates of cardiovascular death and death from any cause were not increased.
Subjects with preexisting cardiovascular conditions who were receiving long-term sibutramine treatment had an increased risk of nonfatal myocardial infarction and nonfatal stroke but not of cardiovascular death or death from any cause. (Funded by Abbott; ClinicalTrials.gov number, NCT00234832.)
People often draw on their current affective experience to inform their decisions, yet little is known about the underlying mechanisms of this process. Understanding them has important implications ...for many big questions in both the affective and decision sciences. Do the same neural circuits that generate affect generate value? What differentiates people who have greater contextual flexibility in their reliance on affect? Do affective choices invoke processes that are distinct from less affective choices? To investigate these questions, we developed a neurocomputational model of affect-informed choice, in which people convert subjective affect into context-sensitive decision value through a process of weighted evidence accumulation. We then tested model predictions by recording electroencephalography and facial electromyography during a novel affective choice paradigm in a sample of racially diverse undergraduate participants (data collected in 2018–2019). In addition to validating our model, we found that generation of affective responses occurs earlier than, and is neurally distinct from, valuation of that affect. Moreover, individual differences in contextual flexibility of affective weighting correlated only with later valuation processes, not earlier affect generation processes. Our results have important theoretical implications for emotion, emotion regulation, and decision making. (PsycInfo Database Record (c) 2024 APA, all rights reserved) (Source: journal abstract)
We experimentally demonstrate an on-chip electro-optic circuit for realizing arbitrary nonlinear activation functions for optical neural networks (ONNs). The circuit operates by converting a small ...portion of the input optical signal into an electrical signal and modulating the intensity of the remaining optical signal. Electrical signal processing allows the activation function circuit to realize any optical-to-optical nonlinearity that does not require amplification. Such line shapes are not constrained to those of conventional optical nonlinearities. Through numerical simulations, we demonstrate that the activation function improves the performance of an ONN on the MNIST image classification task. Moreover, the activation circuit allows for the realization of nonlinearities with far lower optical signal attenuation, paving the way for much deeper ONNs.
Short-wavelength infrared radiation has been successfully applied to accelerate the acid digestion of refractory rare-earth ore samples. Determinations were achieved with microwave plasma-atomic ...emission spectrometry (MP-AES) and dynamic reaction cell – inductively coupled plasma-mass spectrometry (DRC-ICP-MS). The digestion method developed was able to tackle high iron-oxide and silicate matrices using only phosphoric acid in a time frame of only 8min, and did not require perchloric or hydrofluoric acid. Additionally, excellent recoveries and reproducibilities of the rare earth elements, as well as uranium and thorium, were achieved. Digestions of the certified reference materials OREAS-465 and REE-1, with radically different mineralogies, delivered results that mirror those obtained by fusion processes. For the rare-earth CRM OKA-2, whose REE data are provisional, experimental data for the rare-earth elements were generally higher than the provisional values, often exceeding z-values of +2. Determined values for Th and U in this reference material, for which certified values are available, were in excellent agreement.
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•Elimination of toxic (hydrofluoric acid) and potentially explosive (perchloric acid) reagents.•Rapid (8min) acid digestions of refractory ores of rare-earth elements.•Excellent recoveries of all rare-earth elements, thorium and uranium.•Provides data similar to those obtained by fusion techniques (fusion appears to be the preferred digestion technique for REE ores.
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