The Inveon dedicated PET (DPET) scanner is the latest generation of preclinical PET systems devoted to high-resolution and high-sensitivity murine model imaging. In this study, we report on its performance based on the National Electrical Manufacturers Association (NEMA) NU-4 standards. Methods: The Inveon DPET consists of 64 lutetium oxyorthosilicate block detectors arranged in 4 contiguous rings, with a 16.1-cm ring diameter and a 12.7-cm axial length. Each detector block consists of a 20 · 20 lutetium oxyorthosilicate crystal array of 1.51 · 1.51 · 10.0 mm elements. The scintillation light is transmitted to position-sensitive photomultiplier tubes via optical light guides. Energy resolution, spatial resolution, sensitivity, scatter fraction, and counting-rate performance were evaluated. The NEMA NU-4 image-quality phantom and a healthy mouse injected with 18 F-FDG and 18 F 2 were scanned to evaluate the imaging capability of the Inveon DPET. Results: The energy resolution at 511 keV was 14.6% on average for the entire system. In-plane radial and tangential resolutions reconstructed with Fourier rebinning and filtered backprojection algorithms were below 1.8-mm full width at half maximum (FWHM) at the center of the field of view. The radial and tangential resolution remained under 2.0 mm, and the axial resolution remained under 2.5-mm FWHM within the central 4-cm diameter of the field of view. The absolute sensitivity of the system was 9.3% for an energy window of 250-625 keV and a timing window of 3.432 ns. At a 350-to 625-keV energy window and a 3.432-ns timing window, the peak noise equivalent counting rate was 1,670 kcps at 130 MBq for the mouse-sized phantom and 590 kcps at 110 MBq for the rat-sized phantom. The scatter fractions at the same acquisition settings were 7.8% and 17.2% for the mouse-and rat-sized phantoms, respectively. The mouse image-quality phantom results demonstrate that for typical mouse acquisitions, the image quality correlates well with the measured performance parameters in terms of image uniformity, recovery coefficients, attenuation, and scatter corrections. Conclusion: The Inveon system, compared with previous generations of preclinical PET systems from the same manufacturer, shows significantly improved energy resolution, sensitivity, axial coverage, and counting-rate capabilities. Tomographi c systems dedicated to noninvasive, in vivo imaging of preclinical animal models have been widely used at research institutes in recent years (1,2). With the ability to longitudinally image the same subject, each individual animal can serve as its own control. Therefore, intersubject variability can be minimized. Because of the dramatic difference in size between humans and rodents, small-animal PET imposes higher performance requirements than does clinical PET, particularly on image resolution and sensitivity. The resolution and sensitivity improvements are mainly achieved by using smaller crystal sizes, smaller detector ring diameters, and longer axial coverage. With the goal of improving...
BackgroundThe effectiveness of low-fat diets for long-term weight loss has been debated for decades, with dozens of randomized trials (RCTs) and recent reviews giving mixed results.MethodsWe conducted a random effects meta-analysis of RCTs to estimate the long-term effect of low-fat vs. higher fat dietary interventions on weight loss. Our search included RCTs conducted in adult populations reporting weight change outcomes at ≥1 year, comparing low-fat with higher fat interventions, published through July 2014. The primary outcome measure was mean difference in weight change between interventions.FindingsFifty-three studies met inclusion criteria representing 68,128 participants. In the setting of weight loss trials, low-carbohydrate interventions led to significantly greater weight loss than low-fat interventions (n comparisons=18; weighted mean difference [WMD]=1.15 kg, 95% CI=0.52 to 1.79; I2=10%). Low-fat did not lead to differences in weight change compared with other moderate fat weight loss interventions (n=19; WMD=0.36, 95% CI=-0.66 to 1.37; I2=82%), and were superior only when compared with “usual diet” (n=8; WMD=-5.41, 95% CI=-7.29 to −3.54; I2=68%). Similarly, non-weight loss trials and weight maintenance trials, for which there were no low-carbohydrate comparisons, had similar effects for low-fat vs moderate fat interventions, and were superior compared with “usual diet”. Weight loss trials achieving a greater difference in fat intake at follow-up significantly favored the higher fat dietary interventions, as indicated by difference of ≥5% of calories from fat (n=18; WMD=1.04, 95% CI=0.06 to 2.03; I2=78%) or by difference in change serum triglycerides of ≥5 mg/dL (n=17; WMD=1.38, 95% CI=0.50 to 2.25; I2=62%).InterpretationThese findings suggest that the long-term effect of low-fat diets on body weight depends on the intensity of intervention in the comparison group. When compared to dietary interventions of similar intensity, evidence from RCTs does not support low-fat diets over other dietary interventions.
We report the experimental observation of Landau quantization of molecular beam epitaxy grown Sb{2}Te{3} thin films by a low-temperature scanning tunneling microscope. Different from all the reported systems, the Landau quantization in a Sb{2}Te{3} topological insulator is not sensitive to the intrinsic substitutional defects in the films. As a result, a nearly perfect linear energy dispersion of surface states as a 2D massless Dirac fermion system is achieved. We demonstrate that four quintuple layers are the thickness limit for a Sb{2}Te{3} thin film being a 3D topological insulator. The mechanism of the Landau-level broadening is discussed in terms of enhanced quasiparticle lifetime.
Objective: To determine changes in oral health-related quality of life (OHRQoL) during fixed orthodontic appliance therapy in Chinese patients.
An electronic skin (e-skin) that can detect both normal and tangential forces with a differentiable signals output is essential for wearable electronics. A flexible, stretchable, and highly sensitive tactile sensor is presented that enables the detection of both normal and tangential forces, with specific opposite and thus easily being differentiated resistance changing outputs. The e-skin, which is based on two-sublayered carbon nanotubes (CNTs)/ graphene oxide (GO) hybrid 3D conductive networks, that are anchored on a thin porous polydimethylsiloxane (PDMS) layer, is synthesized via a porogen (GO wrapped NaCl) assisted self-assembling process. The fabricated CNTs/ GO@PDMS-based e-skin shows superior sensitivity (gauge factor of 2.26 under a pressure loading of 1 kPa) to tangential force, moderate sensitivity (−0.31 kPa −1 at 0.05-3.8 kPa, and −0.03 kPa −1 at 3.8-6.3 kPa, respectively) to normal force, and a high-reproducible response over 5000 loading cycles including stretching, bending, and shearing. For applications, the e-skin can not only detect wrist pulsing, discriminating different roughness of surfaces, but also produce an obvious responding to an extremely slight ticking (<20 mg) from a feather, and even can real-timely monitor human's breath and music in rhythm.
Background: Few prospective studies have examined dairy fat in relation to cardiovascular disease (CVD). Objective: We aimed to evaluate the association between dairy fat and incident CVD in US adults. Design: We followed 43,652 men in the Health Professionals FollowUp Study , 87,907 women in the Nurses ' Health Study (1980, and 90,675 women in the Nurses' Health Study II (1991II ( -2011. Dairy fat and other fat intakes were assessed every 4 y with the use of validated food-frequency questionnaires. Results: During 5,158,337 person-years of follow-up, we documented 14,815 incident CVD cases including 8974 coronary heart disease cases (nonfatal myocardial infarction or fatal coronary disease) and 5841 stroke cases. In multivariate analyses, compared with an equivalent amount of energy from carbohydrates (excluding fruit and vegetables), dairy fat intake was not significantly related to risk of total CVD (for a 5% increase in energy from dairy fat, the RR was 1.02; 95% CI: 0.98, 1.05), coronary heart disease (RR: 1.03; 95% CI: 0.98, 1.09), or stroke (RR: 0.99; 95% CI: 0.93, 1.05) (P . 0.05 for all). In models in which we estimated the effects of exchanging different fat sources, the replacement of 5% of energy intake from dairy fat with equivalent energy intake from polyunsaturated fatty acid (PUFA) or vegetable fat was associated with 24% (RR: 0.76; 95% CI: 0.71, 0.81) and 10% (RR: 0.90; 95% CI: 0.87, 0.93) lower risk of CVD, respectively, whereas the 5% energy intake substitution of other animal fat with dairy fat was associated with 6% increased CVD risk (RR: 1.06; 95% CI: 1.02, 1.09). Conclusions: The replacement of animal fats, including dairy fat, with vegetable sources of fats and PUFAs may reduce risk of CVD. Whether the food matrix may modify the effect of dairy fat on health outcomes warrants further investigation.
Aims/hypothesis Studies suggest a potential link between low-grade metabolic acidosis and type 2 diabetes. A western dietary pattern increases daily acid load but the association between diet-dependent acid load and type 2 diabetes is still unclear. This study aimed to assess whether diet-dependent acid load is associated with the risk of type 2 diabetes. Methods We examined the association between energy-adjusted net endogenous acid production (NEAP), potential renal acid load (PRAL) and animal protein-to-potassium ratio (A:P) on incident type 2 diabetes in 67,433 women from the Nurses’ Health Study, 84,310 women from the Nurses’ Health Study II and 35,743 men from the Health Professionals’ Follow-up Study who were free from type 2 diabetes, cardiovascular disease and cancer at baseline. Study-specific HRs were estimated using Cox proportional hazards models with time-varying covariates and were pooled using a random effects meta-analysis. Results We documented 15,305 cases of type 2 diabetes during 4,025,131 person-years of follow-up. After adjustment for diabetes risk factors, dietary NEAP, PRAL and A:P were positively associated with type 2 diabetes (pooled HR [95% CI] for highest (Q5) vs lowest quintile (Q1): 1.29 [1.22, 1.37], ptrend <0.0001; 1.29 [1.22, 1.36], ptrend <0.0001 and 1.32 [1.24, 1.40], ptrend <0.0001 for NEAP, PRAL and A:P, respectively). These results were not fully explained by other dietary factors including glycaemic load and dietary quality (HR [95% CI] for Q5 vs Q1: 1.21 [1.09, 1.33], ptrend <0.0001; 1.19 [1.08, 1.30] and 1.26 [1.17, 1.36], ptrend <0.0001 for NEAP, PRAL and A:P, respectively). Conclusions/interpretation This study suggests that higher diet-dependent acid load is associated with an increased risk of type 2 diabetes. This association is not fully explained by diabetes risk factors and overall diet quality.
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