5,007 research outputs found
Auxetic structure for increased power output of strain vibration energy harvester (article)
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordAll data created during this research are in ORE at: https://doi.org/10.24378/exe.703This paper develops an auxetic (negative Poissonās ratio) piezoelectric energy harvester
(APEH) to increase the power output when harnessing strain energy. The APEH consists
of a piezoelectric element bonded to an auxetic substrate. The auxetic substrate
concentrates the stress and strain into the piezoelectric elementās region and introduces
auxetic behaviour in the piezoelectric element, both of which increase the electric power
output. A finite element model was developed to optimise the design and verify the
mechanism of the power increase. Three APEHs were manufactured and characterised.
Their performance was compared with two equivalent strain energy harvesters with plain
substrates. Experimental results show that the APEHs, excited by sinusoidal strains peak
to-peak of 250 Ī¼Īµ at 10 Hz, are able to produce electric power of up to 191.1 ĀµW, which is
14.4 times of the peak power produced by the plain harvesters (13.4 ĀµW). The power gain
factor is constant between samples as the amplitude and frequency of their applied strains
are varied. The model and experimental results are in good agreement, once accounting for
the imperfect bonding of the epoxy using the spring constant of the Thin Elastic Layers on
the modelled epoxy surfaces.We
acknowledge financial support from the Engineering and Physical Sciences Research Council (EPSRC) of the
United Kingdom, via the EPSRC Centre for Doctoral Training in Metamaterials (Grant No. EP/L015331/1
Can exercise limits prevent post-exertional malaise in chronic fatigue syndrome? An uncontrolled clinical trial.
<b>Objective</b>: It was hypothesized that the use of exercise limits prevents symptom increases and worsening of their health status following a walking exercise in people with Chronic Fatigue Syndrome (CFS).
<b>Design</b>: An uncontrolled clinical trial (semi-experimental design).
<b>Setting</b>: Outpatient clinic of a university department.
<b>Subjects</b>: 24 patients with CFS.
<b>Interventions</b>: Subjects undertook a walking test with the two concurrent exercise limits. Each subject walked at an <i>intensity</i> where the maximum heart rate was determined by heart rate corresponding to the respiratory exchange ratio =1.0 derived from a previous sub-maximal exercise test and for a duration calculated from how long each patient felt they were able to walk.
<b>Main outcome measures</b>: The Short Form 36 Health Survey or SF-36, the CFS Symptom List, and the CFS-Activities and Participation Questionnaire were filled in prior to, immediately and 24 hours post-exercise.
<b>Results</b>: The fatigue increase observed immediately post-exercise (p=0.006) returned to pre-exercise levels 24 hours post-exercise. The increase in pain observed immediately post-exercise was retained at 24 hours post-exercise (p=0.03). Fourteen of 24 subjects experienced a clinically meaningful change in bodily pain (change of SF-36 bodily pain score Ā³10). Six of 24 participants indicated that the exercise bout had slightly worsened their health status, and 2 of 24 had a clinically meaningful decrease in vitality (change of SF-36 vitality score Ā³20). There was no change in activity limitations/participation restrictions.
<b>Conclusion</b>: It was shown that the use of exercise limits (limiting both the intensity and duration of exercise) prevents important health status changes following a walking exercise in people with CFS, but was unable to prevent short-term symptom increases
Biochemical profile of heifers with spontaneous humeral fractures suggest that protein-energy malnutrition could be an important factor in the pathology of this disease.
CAUL Read and Publish Agreement.CASE HISTORY: Serum and liver samples from 35, 2-year-old dairy heifers that had fractured one or both humeri post-calving between July and December 2019 were submitted to a diagnostic laboratory for analysis. Serum samples were analysed for albumin, Ī²-hydroxybutyrate (BHB), creatinine, Ca, Mg, phosphate, non-esterified fatty acids (NEFA), and serum Cu concentration. Liver samples were analysed for liver Cu concentration. Data were compared to published reference intervals. Data values for heifers that prior to fracture had grazed fodder beet were also compared to values for those that had grazed pasture. CLINICAL FINDINGS: Sixty-nine percent of heifers with humeral fracture had serum creatinine concentrations below the lower value of the reference range (55-130 Āµmol/L). In 3/32 (9%) heifers, serum NEFA concentrations were increased above the reference value indicating body fat mobilisation (ā„1.2ā
mmol/L for peri-partum cows) and in 20/35 (57%) heifers BHB serum concentrations were above the reference value indicating subclinical ketosis (ā„1.1ā
mmol/L for peri-partum cows). In 24/35 (69%) heifers, liver Cu concentration was low (ā¤ 44 Āµmol/kg) or marginal (45-94 Āµmol/kg). The concentration of Cu in serum was low (ā¤ 4.5ā
Āµmol/L) in 2/33 (6%) heifers and marginal (4.6-7.9 Āµmol/L) in 5/33 (15%) heifers. There was moderate positive correlation between the logged concentrations of Cu in paired liver and serum samples, r(31)ā=ā0.43; (95% CIā=ā0.1-0.79; pā=ā0.014). One heifer had a serum phosphate concentration below the lower limit of the reference range (< 1.10ā
mmol/L). For all heifers, the concentrations of albumin, Ca, and Mg in serum were within the reference intervals (23-38ā
g/L, 2.00-2.60ā
mmol/L, and 0.49-1.15ā
mmol/L respectively). Over winter, 15/35 (43%) heifers grazed predominantly pasture, 14/35 (40%) grazed fodder beet and 6/35 (17%) had a mixed diet. CLINICAL RELEVANCE: In some of these heifers with humeral fractures, there was evidence for protein and/or energy malnutrition in the form of elevated NEFA and BHB concentrations and low creatinine concentrations in serum. Liver Cu concentrations were also reduced in most affected heifers. However, the absence of a control group means it is not possible to determine if these are risk factors for fracture or features common to all periparturient heifers. Clinical trials and molecular studies are needed to determine the true contribution of Cu and protein-energy metabolism to the pathogenesis of spontaneous humeral fractures in dairy heifers. ABBREVIATIONS: BHB: Ć-hydroxybutyrate; NEFA: Non-esterified fatty acids.Publishe
The future of mammary stem cell biology: the power of in vivo transplants
The recent review by Smith and Medina [1] of in vivo transplantation models and their role in investigating mammary stem cell (MaSC) biology provides comprehensive coverage of the history and complexity of the āgold standard ā MaSC assay in mice. This includes a description of the pioneering studies that showed that mammary epithelial outgrowths can be generated in cleared mammary fat pads transplanted with explants or admixtures of mammary cells [2]. However, this approach clearly does not lend itself to prospective analysis of isolated subpopulations in order to identify which cells possess in vivo regenerative activity. More recently, success in obtaining complex mammary gland structures from transplanted suspensions of single cells has now made this possible [3-7]. Moreover, the regenerated structures have been shown to contain daughter cells with the same in viv
Dynamical modeling of collective behavior from pigeon flight data: flock cohesion and dispersion
Several models of flocking have been promoted based on simulations with
qualitatively naturalistic behavior. In this paper we provide the first direct
application of computational modeling methods to infer flocking behavior from
experimental field data. We show that this approach is able to infer general
rules for interaction, or lack of interaction, among members of a flock or,
more generally, any community. Using experimental field measurements of homing
pigeons in flight we demonstrate the existence of a basic distance dependent
attraction/repulsion relationship and show that this rule is sufficient to
explain collective behavior observed in nature. Positional data of individuals
over time are used as input data to a computational algorithm capable of
building complex nonlinear functions that can represent the system behavior.
Topological nearest neighbor interactions are considered to characterize the
components within this model. The efficacy of this method is demonstrated with
simulated noisy data generated from the classical (two dimensional) Vicsek
model. When applied to experimental data from homing pigeon flights we show
that the more complex three dimensional models are capable of predicting and
simulating trajectories, as well as exhibiting realistic collective dynamics.
The simulations of the reconstructed models are used to extract properties of
the collective behavior in pigeons, and how it is affected by changing the
initial conditions of the system. Our results demonstrate that this approach
may be applied to construct models capable of simulating trajectories and
collective dynamics using experimental field measurements of herd movement.
From these models, the behavior of the individual agents (animals) may be
inferred
Adolescentsā responses to the promotion and flavouring of e-cigarettes
Objectives
The purpose of the study is to examine adolescentsā awareness of e-cigarette marketing and investigate the impact of e-cigarette flavour descriptors on perceptions of product harm and user image.
Methods
Data come from the 2014 Youth Tobacco Policy Survey, a cross-sectional in-home survey conducted with 11ā16 year olds across the UK (n = 1205). Adolescentsā awareness of e-cigarette promotion, brands, and flavours was assessed. Perceptions of product harm, and likely user of four examples of e-cigarette flavours was also examined.
Results
Some participants had tried e-cigarettes (12 %) but regular use was low (2 %) and confined to adolescents who had also smoked tobacco. Most were aware of at least one promotional channel (82 %) and that e-cigarettes came in different flavours (69 %). Brand awareness was low. E-cigarettes were perceived as harmful (M = 3.54, SD = 1.19) but this was moderated by product flavours. Fruit and sweet flavours were perceived as more likely to be tried by young never smokers than adult smokers trying to quit (p < 0.001).
Conclusions
There is a need to monitor the impact of future market and regulatory change on youth uptake and perceptions of e-cigarettes
Cerebrospinal fluid and plasma neurofilament light relate to abnormal cognition
Introduction
Neuroaxonal damage may contribute to cognitive changes preceding clinical dementia. Accessible biomarkers are critical for detecting such damage.
Methods
Plasma and cerebrospinal fluid (CSF) neurofilament light (NFL) were related to neuropsychological performance among Vanderbilt Memory & Aging Project participants (plasma n = 333, 73 Ā± 7 years; CSF n = 149, 72 Ā± 6 years) ranging from normal cognition (NC) to mild cognitive impairment (MCI). Models adjusted for age, sex, race/ethnicity, education, apolipoprotein E Īµ4 carriership, and Framingham Stroke Risk Profile.
Results
Plasma NFL was related to all domains (P values ā¤ .008) except processing speed (P values ā„ .09). CSF NFL was related to memory and language (P values ā¤ .04). Interactions with cognitive diagnosis revealed widespread plasma associations, particularly in MCI participants, which were further supported in head-to-head comparison models.
Discussion
Plasma and CSF NFL (reflecting neuroaxonal injury) relate to cognition among non-demented older adults albeit with small to medium effects. Plasma NFL shows particular promise as an accessible biomarker with relevance to cognition in MCI
Re-evaluation of mammary stem cell biology based on in vivo transplantation
Over nearly half a century, transplantation methods have been employed to regenerate the mammary gland in vivo. Recent highly cited reports claim to have demonstrated the regeneration of an entire functional mammary gland from a single mammary epithelial cell. Nevertheless, re-examination of the literature on the transplantation biology of mammary gland regeneration reveals that a complex, combinatorial interaction between variously differentiated mammary epithelial cells and the mammary fat pad stroma is indispensable to this process. In the present article, these issues are reviewed and discussed to provide a greater understanding of the complexity of these multiplex interactions
Effect of antiandrogen flutamide on measures of hepatic regeneration in rats
Male rat liver undergoes a process of demasculinization during hepatic regeneration following partial hepatectomy. The possibility that antiandrogens might potentiate this demasculinization process and in so doing augment the hepatic regenerative response was investigated. Adult male Wistar rats were treated with the antiandrogen flutamide (2 mg/rat/day or 5 mg/rat/day subcutaneously) or vehicle for three days prior to and daily after a 70% partial hepatectomy. At various times after hepatectomy, the liver remnants were removed and weighed. Rates of DNA and polyamine synthesis were assessed by measuring thymidine kinase and ornithine decarboxylase activities, respectively. Hepatic estrogen receptor status and the activity of alcohol dehydrogenase, an androgen-sensitive protein, were measured. Prior to surgery, the administration of 5 mg/day flutamide reduced the hepatic cytosolic androgen receptor activity by 98% and hepatic cytosolic estrogen receptor content by 92% compared to that present in vehicle-treated controls. After hepatectomy, however, all differences in sex hormone receptor activity between the treatment groups were abolished. The rate of liver growth after partial hepatectomy in the three groups was identical. Moreover, hepatectomy-induced increases in ornithine decarboxylase activity and thymidine kinase activity were comparable. These data demonstrate that, although flutamide administration initially alters the sex hormone receptor status of the liver, these affects have no effect on the hepatic regenerative response following a partial hepatectomy. Ā© 1989 Plenum Publishing Corporation
Metabolomic Profiling of Plasma from Melioidosis Patients Using UHPLC-QTOF MS Reveals Novel Biomarkers for Diagnosis
Ā© 2016 by the authors; licensee MDPI, Basel, Switzerland.To identify potential biomarkers for improving diagnosis of melioidosis, we compared plasma metabolome profiles of melioidosis patients compared to patients with other bacteremia and controls without active infection, using ultra-high-performance liquid chromatography-electrospray ionization-quadruple time-of-flight mass spectrometry. Principal component analysis (PCA) showed that the metabolomic profiles of melioidosis patients are distinguishable from bacteremia patients and controls. Using multivariate and univariate analysis, 12 significant metabolites from four lipid classes, acylcarnitine (n = 6), lysophosphatidylethanolamine (LysoPE) (n = 3), sphingomyelins (SM) (n = 2) and phosphatidylcholine (PC) (n = 1), with significantly higher levels in melioidosis patients than bacteremia patients and controls, were identified. Ten of the 12 metabolites showed area-under-receiver operating characteristic curve (AUC) >0.80 when compared both between melioidosis and bacteremia patients, and between melioidosis patients and controls. SM(d18:2/16:0) possessed the largest AUC when compared, both between melioidosis and bacteremia patients (AUC 0.998, sensitivity 100% and specificity 91.7%), and between melioidosis patients and controls (AUC 1.000, sensitivity 96.7% and specificity 100%). Our results indicate that metabolome profiling might serve as a promising approach for diagnosis of melioidosis using patient plasma, with SM(d18:2/16:0) representing a potential biomarker. Since the 12 metabolites were related to various pathways for energy and lipid metabolism, further studies may reveal their possible role in the pathogenesis and host response in melioidosis.published_or_final_versio
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