162 research outputs found

    Nucleon excited states on the lattice

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    We study the pion-nucleon system in s-wave in the framework of lattice QCD in order to gain new information on the nucleon excited states. We perform simulations for nf=2n_f =2 mass degenerate light quarks at a pion mass of 266 MeV. The results show that including the two-particle states drastically changes the energy levels. The variational analysis and the distillation approach play an important role in the extraction of the energy levels. The phase shift analysis allows to extract information on the resonance nature of the observed states.Comment: 6 pages, 2 figures, talk presented at Excited QCD 2013, Bjelasnica Mountain, Sarajev

    Interface engineering for perovskite solar cells based on 2d‐materials: A physics point of view

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    The last decade has witnessed the advance of metal halide perovskites as a promising low-cost and efficient class of light harvesters used in solar cells (SCs). Remarkably, the efficiency of lab-scale perovskite solar cells (PSCs) reached a power conversion efficiency of 25.5% in just similar to 10 years of research, rivalling the current record of 26.1% for Si-based PVs. To further boost the performances of PSCs, the use of 2D materials (such as graphene, transition metal dichalcogenides and transition metal carbides, nitrides and carbonitrides) has been proposed, thanks to their remarkable optoelectronic properties (that can be tuned with proper chemical composition engineering) and chemical stability. In particular, 2D materials have been demonstrated as promising candidates for (i) accelerating hot carrier transfer across the interfaces between the perovskite and the charge extraction layers; (ii) improving the crystallization of the perovskite layers (when used as additives in the precursor solution); (iii) favoring electronic bands alignment through tuning of the work function. In this mini-review, we discuss the physical mechanisms underlying the increased efficiency of 2D material-based PSCs, focusing on the three aforementioned effects

    Advances in Perovskites for Photovoltaic Applications in Space

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    Perovskites have emerged as promising light harvesters in photovoltaics. The resulting solar cells (i) are thin and lightweight, (ii) can be produced through solution processes, (iii) mainly use low-cost raw materials, and (iv) can be flexible. These features make perovskite solar cells intriguing as space technologies; however, the extra-terrestrial environment can easily cause the premature failure of devices. In particular, the presence of highenergy radiation is the most dangerous factor that can damage space technologies. This Review discusses the status and perspectives of perovskite photovoltaics in space applications. The main factors used to describe the space environment are introduced, and the results concerning the radiation hardness of perovskites toward protons, electrons, neutrons, and gamma-rays are presented. Emphasis is given to the physicochemical processes underlying radiation damage in such materials. Finally, the potential use of perovskite solar cells in extra-terrestrial conditions is discussed by considering the effects of the space environment on the choice of the architecture and components of the devices

    The role of fetal, infant, and childhood nutrition in the timing of sexual maturation

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    Puberty is a crucial developmental stage in the life span, necessary to achieve reproductive and somatic maturity. Timing of puberty is modulated by and responds to central neurotransmitters, hormones, and environmental factors leading to hypothalamic-pituitary-gonadal axis maturation. The connection between hormones and nutrition during critical periods of growth, like fetal life or infancy, is fundamental for metabolic adaptation response and pubertal development control and prediction. Since birth weight is an important indicator of growth estimation during fetal life, restricted prenatal growth, such as intrauterine growth restriction (IUGR) and small for gestational age (SGA), may impact endocrine system, affecting pubertal development. Successively, lactation along with early life optimal nutrition during infancy and childhood may be important in order to set up timing of sexual maturation and provide successful reproduction at a later time. Sexual maturation and healthy growth are also influenced by nutrition requirements and diet composition. Early nutritional surveillance and monitoring of pubertal development is recommended in all children, particularly in those at risk, such as the ones born SGA and/or IUGR, as well as in the case of sudden weight gain during infancy. Adequate macro and micronutrient intake is essential for healthy growth and sexual maturity

    The antagonism of the prokineticin system counteracts bortezomib induced side effects: Focus on mood alterations

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    The development of neuropathy and of mood alterations is frequent after chemotherapy. These complications, independent from the antitumoral mechanism, are interconnected due to an overlapping in their processing pathways and a common neuroinflammatory condition. This study aims to verify whether in mice the treatment with the proteasome inhibitor bortezomib (BTZ), at a protocol capable of inducing painful neuropathy, is associated with anxiety, depression and supraspinal neuroinflammation. We also verify if the therapeutic treatment with the antagonist of the prokineticin (PK) system PC1, which is known to contrast pain and neuroinflammation, can prevent mood alterations. Mice were treated with BTZ (0.4 mg/kg three times/week for 4 weeks); mechanical allodynia and locomotor activity were evaluated over time while anxiety (dark light and marble burying test), depression (sucrose preference and swimming test) and supraspinal neuroinflammation were checked at the end of the protocol. BTZ treated neuropathic mice develop anxiety and depression. The presence of mood alterations is related to the presence of neuroinflammation and PK system activation in prefrontal cortex, hippocampus and hypothalamus with high levels of PK2 and PKR2 receptor, IL‐6 and TNF‐α, TLR4 and an upregulation of glial markers. PC1 treatment, counteracting pain, prevented the development of supraspinal inflammation and depression‐like behavior in BTZ mice

    Predictive ability of the estimate of fat mass to detect early-onset metabolic syndrome in prepubertal children with obesity

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    Body mass index (BMI), usually used as a body fatness marker, does not accurately dis-criminate between amounts of lean and fat mass, crucial factors in determining metabolic syndrome (MS) risk. We assessed the predictive ability of the estimate of FM (eFM) calculated using the following formula: FM = weight − exp(0.3073 × height2 −10.0155×d-growth-standards/standards/body-mass-index-for-age-bmi-for-age weight−1 +0.004571×weight− 0.9180×ln(age) + 0.6488×age0.5 + 0.04723×male + 2.8055) (exp = exponential function, score 1 if child was of black (BA), south Asian (SA), other Asian (AO), or other (other) ethnic origin and score 0 if not, ln = natural logarithmic transformation, male = 1, female = 0), to detect MS in 185 prepubertal obese children compared to other adiposity parameters. The eFM, BMI, waist circumference (WC), body shape index (ABSI), tri-ponderal mass index, and conicity index (C-Index) were calculated. Patients were classified as hav-ing MS if they met ≄ 3/5 of the following criteria: WC ≄ 95th percentile; triglycerides ≄ 95th percen-tile; HDL-cholesterol ≀ 5th percentile; blood pressure ≄ 95th percentile; fasting blood glucose ≄ 100 mg/dL; and/or HOMA-IR ≄ 97.5th percentile. MS occurred in 18.9% of obese subjects (p < 0.001), with a higher prevalence in females vs. males (p = 0.005). The eFM was correlated with BMI, WC, ABSI, and Con-I (p < 0.001). Higher eFM values were present in the MS vs. non-MS group (p < 0.001); the eFM was higher in patients with hypertension and insulin resistance (p <0.01). The eFM shows a good predictive ability for MS. Additional to BMI, the identification of new parameters determi-nable with simple anthropometric measures and with a good ability for the early detection of MS, such as the eFM, may be useful in clinical practice, particularly when instrumentation to estimate the body composition is not available

    Solar Energy in Space Applications: Review and Technology Perspectives

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    Solar cells (SCs) are the most ubiquitous and reliable energy generation systems for aerospace applications. Nowadays, III-V multijunction solar cells (MJSCs) represent the standard commercial technology for powering spacecraft, thanks to their high-power conversion efficiency and certified reliability/stability while operating in orbit. Nevertheless, spacecraft companies are still using cheaper Si-based SCs to amortize the launching costs of satellites. Moreover, in recent years, new SCs technologies based on Cu(In,Ga)Se-2 (CIGS) and perovskite solar cells (PSCs) have emerged as promising candidates for aerospace power systems, because of their appealing properties such as lightweightness, flexibility, cost-effective manufacturing, and exceptional radiation resistance. In this review the current advancements and future challenges of SCs for aerospace applications are critically discussed. In particular, for each type of SC, a description of the device's architecture, a summary of its performance, and a quantitative assessment of the radiation resistance are presented. Finally, considering the high potential that 2D-materials (such as graphene, transition metal dichalcogenides, and transition metal carbides, nitrides, and carbonitrides) have in improving both performance and stability of SCs, a brief overview of some important results concerning the influence of radiation on both 2D materials-based devices and monolayer of 2D materials is also included

    Physical activity and sedentary behavior from 6 to 11 years

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    OBJECTIVES: Physical activity (PA) is presumed to decline during childhood and adolescence, but only few long-term studies about PA development during this period of life exist. We assessed PA and sedentary behavior (SB) over a 5-year period to gain a better understanding of the extent of change in activity and potential influencing factors. METHODS: PA and SB of 600 children from the Childhood Obesity Project were objectively measured with the SenseWear Armband 2 at the ages of 6, 8, and 11 years, resulting in 1254 observations. Longitudinal changes of total PA, moderate-to-vigorous physical activity (MVPA), light physical activity (LPA), and SB were modeled with mixed-effects models. RESULTS: Total PA revealed a significant quadratic decline with age (P &lt; .001), resulting in a change of total PA by -75.3 minutes per day from 6 to 11 years. LPA linearly declined (P &lt; .001) by 44.6 minutes per day, MVPA quadratically declined (P &lt; .001) by an overall 30.7 minutes, whereas SB increased significantly (+107 minutes; P = .001). Boys showed a steeper decline in LPA (P = .003) and MVPA (P &lt; .001) than did girls. Higher fat mass index and BMI z scores were associated with lower levels of total PA and MVPA and higher levels of SB (all P &lt; .001). CONCLUSIONS: We showed that PA decreased, and SB increased in earlier years than previously thought. MVPA remained relatively stable until 8 years, but revealed a drop-off at 11 years, identifying this period as a crucial time for intervention
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