Electronic band gap reduction and intense luminescence in Co and Mn ion-implanted SiO2_2

Cobalt and manganese ions are implanted into SiO$_2$ over a wide range of concentrations. For low concentrations, the Co atoms occupy interstitial locations, coordinated with oxygen, while metallic Co clusters form at higher implantation concentrations. For all concentrations studied here, Mn ions remain in interstitial locations and do not cluster. Using resonant x-ray emission spectroscopy and Anderson impurity model calculations, we determine the strength of the covalent interaction between the interstitial ions and the SiO$_2$ valence band, finding it comparable to Mn and Co monoxides. Further, we find an increasing reduction in the SiO$_2$ electronic band gap for increasing implantation concentration, due primarily to the introduction of Mn- and Co-derived conduction band states. We also observe a strong increase in a band of x-ray stimulated luminescence at 2.75 eV after implantation, attributed to oxygen deficient centers formed during implantation.Comment: 8 pages, 6 figure

The effects of partial sleep restriction and altered sleep timing on appetite and food reward.

We examined the effects of partial sleep restriction (PSR) with an advanced wake-time or delayed bedtime on measures of appetite, food reward and subsequent energy intake (EI). Twelve men and 6 women (age: 23 ± 4 years, body fat: 18.8 ± 10.1%) participated in 3 randomized crossover sessions: control (habitual bed- and wake-time), 50% PSR with an advanced wake-time and 50% PSR with a delayed bedtime. Outcome variables included sleep architecture (polysomnography), ad libitum EI (validated food menu), appetite sensations (visual analogue scales), the satiety quotient (SQ; mm/100 kcal) and food reward (Leeds Food Preference Questionnaire and the relative-reinforcing value (RRV) of preferred food task). Increased fasting and post-standard breakfast appetite ratings were noted following PSR with an advanced wake-time compared to the control and PSR with a delayed bedtime sessions (Fasting hunger ratings: 77 ± 16 vs. 65 ± 18 and 64 ± 16; P = 0.01; Post-meal hunger AUC: 5982 ± 1781 vs. 4508 ± 2136 and 5198 ± 2201; P = 0.03). Increased explicit wanting and liking for high-relative to low-fat foods were also noted during the advanced wake-time vs. control session (Explicit wanting: -3.5 ± 12.5 vs. -9.3 ± 8.9, P = 0.01; Explicit liking: -1.6 ± 8.5 vs. -7.8 ± 9.6, P = 0.002). No differences in the RRV of preferred food, the SQ and ad libitum lunch intake were noted between sessions. These findings suggest that appetite sensations and food reward are increased following PSR with an advanced wake-time, rather than delayed bedtime, vs. CONTROL: However, this did not translate into increased EI during a test meal. Given the increasing prevalence of shift workers and incidences of sleep disorders, additional studies are needed to evaluate the prolonged effects of voluntary sleep restriction with altered sleep timing on appetite and EI measurements

Early anterior cingulate involvement is seen in presymptomatic MAPT P301L mutation carriers

BACKGROUND: PET imaging of glucose metabolism has revealed presymptomatic abnormalities in genetic FTD but has not been explored in MAPT P301L mutation carriers. This study aimed to explore the patterns of presymptomatic hypometabolism and atrophy in MAPT P301L mutation carriers. METHODS: Eighteen asymptomatic members from five families with a P301L MAPT mutation were recruited to the study, six mutation carriers, and twelve mutation-negative controls. All participants underwent standard behavioural and cognitive assessment as well as [18F]FDG-PET and 3D T1-weighted MRI brain scans. Regional standardised uptake value ratios (SUVR) for the PET scan and volumes calculated from an automated segmentation for the MRI were obtained and compared between the mutation carrier and control groups. RESULTS: The mean (standard deviation) estimated years from symptom onset was 12.5 (3.6) in the mutation carrier group with a range of 7 to 18 years. No differences in cognition were seen between the groups, and all mutation carriers had a global CDR plus NACC FTLD of 0. Significant reduction in [18F] FDG uptake in the anterior cingulate was seen in mutation carriers (mean 1.25 [standard deviation 0.07]) compared to controls (1.36 [0.09]). A similar significant reduction was also seen in grey matter volume in the anterior cingulate in mutation carriers (0.60% [0.06%]) compared to controls (0.68% [0.08%]). No other group differences were seen in other regions. CONCLUSIONS: Anterior cingulate hypometabolism and atrophy are both apparent presymptomatically in a cohort of P301L MAPT mutation carriers. Such a specific marker may prove to be helpful in stratification of presymptomatic mutation carriers in future trials

Turbulent transport of impurities in 3D devices

A large diffusive turbulent contribution to the radial impurity transport in Wendelstein 7-X (W7-X) plasmas has been experimentally inferred during the first campaigns and numerically confirmed by means of gyrokinetic simulations with the code stella. In general, the absence of strong impurity accumulation during the initial W7-X campaigns is attributed to this diffusive term. In the present work the diffusive contribution is also calculated in other stellarator plasmas. In particular, the diffusion (D) and convection (V) coefficients of carbon and iron impurities produced by ion-temperature-gradient (ITG) turbulence are obtained for W7-X, LHD, TJ-II and NCSX. The results show that, although the size of D and V can differ across the four devices, inward convection is found for all of them. For W7-X, TJ-II and NCSX the two coefficients are comparable and the turbulent peaking factor is surprisingly similar. In LHD, appreciably weaker diffusive and convective impurity transport and significantly larger turbulent peaking factor are predicted. All this suggests that ITG turbulence, although not strongly, would lead to negative impurity density gradients in stellarators. Then, considering mixed ITG/Trapped Electron Mode (TEM) turbulence for the specific case of W7-X, it has been quantitatively assessed to what degree pellet fueled reduced turbulence scenarios feature reduced turbulent transport of impurities as well. The results for trace iron impurities show that, although their turbulent transport is not entirely suppressed, a significant reduction of V and a stronger decrease of D are found. Although the diffusion is still above neoclassical levels, the neoclassical convection would gain under such conditions a greater specific weight on the dynamics of impurities in comparison with standard ECRH scenarios.Comment: 16 pages, 8 figure

Topological principles and developmental algorithms might refine diffusion tractography.

The identification and reconstruction of axonal pathways in the living brain or "ex-vivo" is promising a revolution in connectivity studies bridging the gap from animal to human neuroanatomy with extensions to brain structural-functional correlates. Unfortunately, the methods suffer from juvenile drawbacks. In this perspective paper we mention several computational and developmental principles, which might stimulate a new generation of algorithms and a discussion bridging the neuroimaging and neuroanatomy communities

Deglacial to postglacial history of Nares Strait, Northwest Greenland: a marine perspective from Kane Basin

A radiocarbon-dated marine sediment core retrieved in Kane Basin, central Nares Strait, was analysed to constrain the timing of the postglacial opening of this Arctic gateway and its Holocene evolution. This study is based on a set of sedimentological and geochemical proxies of changing sedimentary processes and sources that provide new insight into the evolution of ice sheet configuration in Nares Strait. Proglacial marine sedimentation at the core site initiated ca. 9.0&thinsp;cal&thinsp;ka&thinsp;BP following the retreat of grounded ice. Varying contributions of sand and clasts suggest unstable sea ice conditions and glacial activity, which subsisted until ca. 7.5&thinsp;cal&thinsp;ka&thinsp;BP under the combined influence of warm atmospheric temperatures and proglacial cooling induced by the nearby Innuitian (IIS) and Greenland (GIS) ice sheets. An interval rich in ice-rafted debris (IRD) is interpreted as the collapse of the ice saddle in Kennedy Channel ca. 8.3&thinsp;cal&thinsp;ka&thinsp;BP that marks the complete opening of Nares Strait and the initial connection between the Lincoln Sea and northernmost Baffin Bay. Delivery of sediment by icebergs was strengthened between ca. 8.3 and ca. 7.5&thinsp;cal&thinsp;ka&thinsp;BP following the collapse of the buttress of glacial ice in Kennedy Channel that triggered the acceleration of GIS and IIS fluxes toward Nares Strait. The destabilisation in glacial ice eventually led to the rapid retreat of the GIS in eastern Kane Basin at about 8.1&thinsp;cal&thinsp;ka&thinsp;BP as evidenced by a noticeable change in sediment geochemistry in our core. The gradual decrease in carbonate inputs to Kane Basin between ∼8.1 and ∼4.1&thinsp;cal&thinsp;ka&thinsp;BP reflects the late deglaciation of Washington Land. The shoaling of Kane Basin can be observed in our record by the increased winnowing of lighter particles as the glacio-isostatic rebound brought the seabed closer to subsurface currents. Reduced iceberg delivery from 7.5 to 1.9&thinsp;cal&thinsp;ka&thinsp;BP inferred by our dataset may be linked to the retreat of the bordering ice sheets on land that decreased their number of marine termini.</p

Burnout: exploring the differences between U.S. and international medical graduates.

Background: International medical graduates (IMGs) have less burnout than U. S. medical school graduates (USMGs) during residency training. This study evaluates possible correlates of differences in burnout rates between USMGs and IMGs. Methods: We surveyed 375 first-year residents at orientation in June/July 2017. We assessed burnout using the Copenhagen Burnout Inventory (CBI) and used validated scales to measure stress, quality of life (QoL), mastery, and spirituality. We collected data on gender, place of graduation, language fluency, and specialty. We compared CBI scores between USMGs and IMGs, performed a multivariate linear regression analysis of relationships between covariates and CBI subscales, and logistic regression analysis for our categorical definition of burnout. Results: Two hundred twenty-two residents responded for a response rate of 59%. Personal, work or patient- related burnout was common among residents, particularly among USMGs. The most common form of burnout was work-related. Forty nine percent of USMGs have work burnout compared to 26% of IMGs (p \u3c 0.01). In multivariate analysis, being an IMG reduced odds of work-related and of total burnout by 50% (OR 0.5 C.I 0.25-0.99). Perceived mastery was associated with reductions in all subscales of burnout (p \u3c 0.05). Stress and low QoL related to personal and work burnout scores (p \u3c 0.01). Conclusion: Work-related burnout is more common among USMGs than in IMGs. Although mastery, QoL and stress were correlates of burnout among all residents, these factors did not explain the difference. Future studies should evaluate the role of medical school structure and curriculum on differences in burnout rates between the two groups

Double-pump technique – one step closer towards efficient liquid-based THz sources

By irradiating a water jet with double pulses, we demonstrate 4-fold higher THz wave generation than for a single pump pulse. The dependence of the enhanced THz signal on the temporal delay between two collinear pulses reveals the optimal time for launching signal pulse is near 2-4 ps, which corresponds to the time needed to create the complete pre-ionization state when sufficient electron density is already induced, and there is no plasma reflection of the pump pulse radiation. The increase in THz waves generation efficiency corresponds to the case of water jet excitation by the pulses with an optimal duration for a certain jet thickness, which is determined by the spatial pulse size. Using a theoretical model of the interaction of a high-intensity sub-picosecond pulse with an isotropic medium, we held a numerical simulation, which well describes the experimental results when using 3 ps value of population relaxation time. Thus, in this work, double pump method allows not only to increase the energy of the generated THz waves, but also to determine the characteristic excited state lifetime of liquid water. The optical-to-terahertz conversion efficiency in case of double pulse excitation of water column is of the order of 0.5·10−3, which exceeds the typical values for THz waves generation during two-color filamentation in air and comparable with the achievable values due to the optical rectification in some crystals

Validation of the SenseWear armband in circuit resistance training with different loads

The use of the SenseWear™ armband (SWA), an objective monitor of physical activity, is a relatively new device used by researchers to measure energy expenditure. These monitors are practical, relatively inexpensive and easy-to-use. The aim of the present study was to assess the validity of SWAs for the measurement of energy expenditure (EE) in circuit resistance training (CRT) at three different intensities in moderately active, healthy subjects. The study subjects (17 females, 12 males) undertook CRT at 30, 50 and 70% of the 15 repetition maximum for each exercise component wearing an SWA as well as an Oxycon Mobile (OM) portable metabolic system (a gold standard method for measuring EE). The EE rose as exercise intensity increased, but was underestimated by the SWAs. For women, Bland-Altman plots showed a bias of 1.13 ± 1.48 METs and 32.1 ± 34.0 kcal in favour of the OM system, while for men values of 2.33 ± 1.82 METs and 75.8 ± 50.8 kcal were recorded