Demand for increased capacity in deep-space to Earth communications systems continues to rise as sensor data rates climb and mission requirements expand. Optical free-space laser communications ...systems offer the potential for operating at data rates 10 to 1000 times that of current radio-frequency systems. A key element in an optical communications system is the Earth receiver. This paper reviews the design of a distributed photon-counting receiver array composed of four meter-class telescopes, developed as a part of the mars laser communications demonstration (MLCD) project. This design offers a cost-effective and adaptable alternative approach to traditional large, single-aperture receive elements while preserving the expected improvement in data rates enabled by free-space laser communications systems. Key challenges in developing distributed receivers and details of the MLCD design are discussed.
For Geiger-mode avalanche photodiodes, the two most important performance metrics for most applications are dark count rate (DCR) and photon detection efficiency (PDE). In 1.06- mu m ...separate-absorber-avalanche (multiplier) InP-based devices, the primary sources of dark counts are tunneling through defect levels in the InP avalanche region and thermal generation in the InGaAsP absorber region. PDE is the probability that a photon will be absorbed (quantum efficiency) times the probability that the electron-hole pair generated will actually cause an avalanche. A device model based on experimental data that can simultaneously predict DCR and PDE as a function of overbias and temperature is presented. This model has been found useful in predicting changes in performance as various device parameters, such as avalanche layer thickness, are modified. This has led to designs that are capable simultaneously of low DCR and high PDE.
Physical fitness is an important prognostic factor in heart failure (HF). To improve fitness, different types of exercise have been explored, with recent focus on high-intensity interval training ...(HIT). We comprehensively compared effects of HIT versus continuous training (CT) in HF patients NYHA II-III on physical fitness, cardiovascular function and structure, and quality of life, and hypothesize that HIT leads to superior improvements compared to CT.
Twenty HF patients (male:female 19:1, 64±8 yrs, ejection fraction 38±6%) were allocated to 12-weeks of HIT (10*1-minute at 90% maximal workload-alternated by 2.5 minutes at 30% maximal workload) or CT (30 minutes at 60-75% of maximal workload). Before and after intervention, we examined physical fitness (incremental cycling test), cardiac function and structure (echocardiography), vascular function and structure (ultrasound) and quality of life (SF-36, Minnesota living with HF questionnaire (MLHFQ)).
Training improved maximal workload, peak oxygen uptake (VO2peak) related to the predicted VO2peak, oxygen uptake at the anaerobic threshold, and maximal oxygen pulse (all P<0.05), whilst no differences were present between HIT and CT (N.S.). We found no major changes in resting cardiovascular function and structure. SF-36 physical function score improved after training (P<0.05), whilst SF-36 total score and MLHFQ did not change after training (N.S.).
Training induced significant improvements in parameters of physical fitness, although no evidence for superiority of HIT over CT was demonstrated. No major effect of training was found on cardiovascular structure and function or quality of life in HF patients NYHA II-III.
Nederlands Trial Register NTR3671.
Atrial fibrillation (AF) is associated with profound structural and functional changes in the atria. In the present study, we investigated the association between left atrial (LA) phasic function and ...the extent of LA fibrosis using advanced cardiovascular magnetic resonance (CMR) imaging techniques, including 3-dimensional (3D) late gadolinium enhancement (LGE) and feature tracking.
Patients with paroxysmal and persistent AF (n = 105) underwent CMR in sinus rhythm. LA global reservoir strain, conduit strain and contractile strain were derived from cine CMR images using CMR feature tracking. The extent of LA fibrosis was assessed from 3D LGE images. Healthy subjects underwent CMR and served as controls (n = 19).
Significantly lower LA reservoir strain, conduit strain and contractile strain were found in AF patients, as compared to healthy controls (- 15.9 ± 3.8% vs. - 21.1 ± 3.6% P < 0.001, - 8.7 ± 2.7% vs. - 12.6 ± 2.5% P < 0.001 and - 7.2 ± 2.3% vs. - 8.6 ± 2.2% P = 0.02, respectively). Patients with a high degree of LA fibrosis (dichotomized by the median value) had lower reservoir strain and conduit strain compared to patients with a low degree of LA fibrosis (- 15.0 ± 3.9% vs. - 16.9 ± 3.3%, P = 0.02 and - 7.9 ± 2.7% vs. - 9.5 ± 2.6%, P = 0.01, respectively). In contrast, no difference was found for LA contractile strain (- 7.1 ± 2.4% vs. - 7.4 ± 2.3%, P = 0.55).
Impaired LA reservoir and conduit strain are present in AF patients with extensive atrial fibrosis. Future studies are needed to examine the biologic nature of this association and possible therapeutic implications.
Myocardial Fibrosis in Athletes van de Schoor, Freek R; Aengevaeren, Vincent L; Hopman, Maria T E ...
Mayo Clinic proceedings,
11/2016, Letnik:
91, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Myocardial fibrosis (MF) is a common phenomenon in the late stages of diverse cardiac diseases and is a predictive factor for sudden cardiac death. Myocardial fibrosis detected by magnetic resonance ...imaging has also been reported in athletes. Regular exercise improves cardiovascular health, but there may be a limit of benefit in the exercise dose-response relationship. Intense exercise training could induce pathologic cardiac remodeling, ultimately leading to MF, but the clinical implications of MF in athletes are unknown. For this comprehensive review, we performed a systematic search of the PubMed and MEDLINE databases up to June 2016. Key Medical Subject Headings terms and keywords pertaining to MF and exercise (training) were included. Articles were included if they represented primary MF data in athletes. We identified 65 athletes with MF from 19 case studies/series and 14 athletic population studies. Myocardial fibrosis in athletes was predominantly identified in the intraventricular septum and where the right ventricle joins the septum. Although the underlying mechanisms are unknown, we summarize the evidence for genetic predisposition, silent myocarditis, pulmonary artery pressure overload, and prolonged exercise-induced repetitive micro-injury as contributors to the development of MF in athletes. We also discuss the clinical implications and potential treatment strategies of MF in athletes.
The 2017 Dutch Physical Activity Guidelines Weggemans, Rianne M; Backx, Frank J G; Borghouts, Lars ...
The international journal of behavioral nutrition and physical activity,
06/2018, Letnik:
15, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The objective of this study was to derive evidence-based physical activity guidelines for the general Dutch population.
Two systematic reviews were conducted of English language meta-analyses in ...PubMed summarizing separately randomized controlled trials and prospective cohort studies on the relation between physical activity and sedentary behaviour on the one hand and the risk of all-cause mortality and incidence of 15 major chronic diseases and conditions on the other hand. Other outcome measures were risk factors for cardiovascular disease and type 2 diabetes, physical functioning, and fitness. On the basis of these reviews, an expert committee derived physical activity guidelines. In deriving the guidelines, the committee first selected only experimental and observational prospective findings with a strong level of evidence and then integrated both lines of evidence.
The evidence found for beneficial effects on a large number of the outcome measures was sufficiently strong to draw up guidelines to increase physical activity and reduce sedentary behaviour, respectively. At the same time, the current evidence did not provide a sufficient basis for quantifying how much physical activity is minimally needed to achieve beneficial health effects, or at what amount sedentary behaviour becomes detrimental. A general tenet was that at every level of current activity, further increases in physical activity provide additional health benefits, with relatively larger effects among those who are currently not active or active only at light intensity. Three specific guidelines on (1) moderate- and vigorous-intensity physical activity, (2) bone- and muscle-strengthening activities, and (3) sedentary behaviour were formulated separately for adults and children.
There is an unabated need for evidence-based physical activity guidelines that can guide public health policies. Research in which physical activity is measured both objectively (quantity) and subjectively (type and quality) is needed to provide better estimates of the type and actual amount of physical activity required for health.
The 2015 Dutch food-based dietary guidelines Kromhout, D; Spaaij, C J K; de Goede, J ...
European journal of clinical nutrition,
08/2016, Letnik:
70, Številka:
8
Journal Article
Recenzirano
Odprti dostop
The objective of this study was to derive food-based dietary guidelines for the Dutch population. The dietary guidelines are based on 29 systematic reviews of English language meta-analyses in PubMed ...summarizing randomized controlled trials and prospective cohort studies on nutrients, foods and food patterns and the risk of 10 major chronic diseases: coronary heart disease, stroke, heart failure, diabetes, breast cancer, colorectal cancer, lung cancer, chronic obstructive pulmonary disease, dementia and depression. The committee also selected three causal risk factors for cardiovascular diseases or diabetes: systolic blood pressure, low-density lipoprotein cholesterol and body weight. Findings were categorized as strong or weak evidence, inconsistent effects, too little evidence or effect unlikely for experimental and observational data separately. Next, the committee selected only findings with a strong level of evidence for deriving the guidelines. Convincing evidence was based on strong evidence from the experimental data either or not in combination with strong evidence from prospective cohort studies. Plausible evidence was based on strong evidence from prospective cohort studies only. A general guideline to eat a more plant food-based dietary pattern and limit consumption of animal-based food and 15 specific guidelines have been formulated. There are 10 new guidelines on legumes, nuts, meat, dairy produce, cereal products, fats and oils, tea, coffee and sugar-containing beverages. Three guidelines on vegetables, fruits, fish and alcoholic beverages have been sharpened, and the 2006 guideline on salt stayed the same. A separate guideline has been formulated on nutrient supplements. Completely food-based dietary guidelines can be derived in a systematic and transparent way.
Background
An inadequate protein intake may offset the muscle protein synthetic response after physical activity, reducing the possible benefits of an active lifestyle for muscle mass. We examined ...the effects of 12 weeks of daily protein supplementation on lean body mass, muscle strength, and physical performance in physically active older adults with a low habitual protein intake (<1.0 g/kg/day).
Methods
A randomized double‐blinded controlled trial was performed among 116 physically active older adults age 69 (interquartile range: 67–73) years, 82% male who were training for a 4 day walking event of 30, 40, or 50 km/day. Participants were randomly allocated to either 31 g of milk protein or iso‐caloric placebo supplementation for 12 weeks. Body composition (dual‐energy X‐ray absorptiometry), strength (isometric leg extension and grip strength), quadriceps contractile function, and physical performance Short Physical Performance Battery, Timed Up‐and‐Go test, and cardiorespiratory fitness (Åstrand–Rhyming submaximal exercise test) were measured at baseline and after 12 weeks. We assessed vitamin D status and markers of muscle damage and renal function in blood and urine samples before and after intervention.
Results
A larger increase in relative lean body mass was observed in the protein vs. placebo group (∆0.93 ± 1.22% vs. ∆0.44 ± 1.40%, PInteraction = 0.046). Absolute and relative fat mass decreased more in the protein group than in the placebo group (∆−0.90 ± 1.22 kg vs. ∆−0.31 ± 1.28 kg, PInteraction = 0.013 and ∆−0.92 ± 1.19% vs. ∆−0.39 ± 1.36%, PInteraction = 0.029, respectively). Strength and contractile function did not change in both groups. Gait speed, chair‐rise ability, Timed Up‐and‐Go, and cardiorespiratory fitness improved in both groups (P < 0.001), but no between‐group differences were observed. Serum urea increased in the protein group, whereas no changes were observed in the placebo group (PInteraction < 0.001). No between‐group differences were observed for vitamin D status, muscle damage, and renal function markers.
Conclusions
In physically active older adults with relatively low habitual dietary protein consumption, an improvement in physical performance, an increase in lean body mass, and a decrease in fat mass were observed after walking exercise training. A larger increase in relative lean body mass and larger reduction in fat mass were observed in participants receiving 12 weeks of daily protein supplementation compared with controls, whereas this was not accompanied by differences in improvements between groups in muscle strength and physical performance.
Telemetric temperature capsule systems are wireless, relatively noninvasive, and easily applicable in field conditions and have therefore great advantages for monitoring core body temperature. ...However, the accuracy and responsiveness of available capsule systems have not been compared previously. Therefore, the aim of this study was to examine the validity, reliability, and inertia characteristics of four ingestible temperature capsule systems (i.e., CorTemp, e-Celsius, myTemp, and VitalSense).
Ten temperature capsules were examined for each system in a temperature-controlled water bath during three trials. The water bath temperature gradually increased from 33°C to 44°C in trials 1 and 2 to assess the validity and reliability, and from 36°C to 42°C in trial 3 to assess the inertia characteristics of the temperature capsules.
A systematic difference between capsule and water bath temperature was found for CorTemp (0.077°C ± 0.040°C), e-Celsius (-0.081°C ± 0.055°C), myTemp (-0.003°C ± 0.006°C), and VitalSense (-0.017°C ± 0.023°C; P < 0.010), with the lowest bias for the myTemp system (P < 0.001). A systematic difference was found between trial 1 and trial 2 for CorTemp (0.017°C ± 0.083°C; P = 0.030) and e-Celsius (-0.007°C ± 0.033°C; P = 0.019), whereas temperature values of myTemp (0.001°C ± 0.008°C) and VitalSense (0.002°C ± 0.014°C) did not differ (P > 0.05). Comparable inertia characteristics were found for CorTemp (25 ± 4 s), e-Celsius (21 ± 13 s), and myTemp (19 ± 2 s), whereas the VitalSense system responded more slowly (39 ± 6 s) to changes in water bath temperature (P < 0.001).
Although differences in temperature and inertia were observed between capsule systems, an excellent validity, test-retest reliability, and inertia was found for each system between 36°C and 44°C after removal of outliers.
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