Superconductive proximity in a Topological Insulator slab and excitations bound to an axial vortex

We consider the proximity effect in a Topological Insulator sandwiched between two conventional superconductors, by comparing s-wave spin singlet superconducting pairing correlations and odd-parity triplet pairing correlations with zero spin component orthogonal to the slab ("polar " phase). A superconducting gap opens in the Dirac dispersion of the surface states existing at the interfaces. An axial vortex is included, piercing the slab along the normal to the interfaces with the superconductors. It is known that, when proximity is s-wave, quasiparticles in the gap are Majorana Bound States, localized at opposite interfaces. We report the full expression for the quantum field associated to the midgap neutral fermions, as derived in the two-orbital band model for the TI. When proximity involves odd-parity pairing, midgap modes are charged Surface Andreev Bound States, and they originate from interfacial circular states of definite chirality, centered at the vortex singularity and decaying in the TI film with oscillations. When the chemical potential is moved away from midgap, extended states along the vortex axis are also allowed. Their orbital structure depends on the symmetry of the bulk band from where the quasiparticle level splits off.Comment: 13 pages no figures, accepted for publication in Phys. Rev.

Advantages of using YBCO-Nanowire-YBCO heterostructures in the search for Majorana Fermions

We propose an alternative platform to observe Majorana bound states in solid state systems. High critical temperature cuprate superconductors can induce superconductivity, by proximity effect, in quasi one dimensional nanowires with strong spin orbit coupling. They favor a wider and more robust range of conditions to stabilize Majorana fermions due to the large gap values, and offer novel functionalities in the design of the experiments determined by different dispersion for Andreev bound states as a function of the phase difference.Comment: 4 Pages, 3 figures, submission date 30-Apr-201

Biological aspects of mTOR in leukemia

The mammalian target of rapamycin (mTOR) is a central processor of intra-and extracellular signals, regulating many fundamental cellular processes such as metabolism, growth, proliferation, and survival. Strong evidences have indicated that mTOR dysregulation is deeply implicated in leukemogenesis. This has led to growing interest in the development of modulators of its activity for leukemia treatment. This review intends to provide an outline of the principal biological and molecular functions of mTOR. We summarize the current understanding of how mTOR interacts with microRNAs, with components of cell metabolism, and with controllers of apoptotic machinery. Lastly, from a clinical/translational perspective, we recapitulate the therapeutic results in leukemia, obtained by using mTOR inhibitors as single agents and in combination with other compounds

The effects of physical activity on balance and postural control in people with down syndrome

People with Down Syndrome (DS) often have impaired balance and postural control and result as less active than their peers, that can lead to reduced quality of life and movement skills. Effects of physical activity may be important in preventing falling risk and health consequences in people with DS. In this context, we conducted a literature search of original articles, published between January 2010 and January 2020, on the effects of physical activity on balance and postural control in people with DS. We found 16 articles from almost all continents, investigating the effects of different types of physical activity on static and dynamic balance and postural control. The included studies reported improvements in both static and dynamic balance with exercise programmes lasting at least 6 weeks and containing strength, aerobic and sensorimotor training. However, the most suitable type of physical activity for people with DS is not clear. In conclusion, physical activity is highly recommendable in people with DS, to improve their balance and prevent falling risk

Metabolic reprogramming promotes myogenesis during aging

Sarcopenia is the age-related progressive loss of skeletal muscle mass and strength finally leading to poor physical performance. Impaired myogenesis contributes to the pathogenesis of sarcopenia, while mitochondrial dysfunctions are thought to play a primary role in skeletal muscle loss during aging. Here we studied the link between myogenesis and metabolism. In particular, we analyzed the effect of the metabolic modulator trimetazidine (TMZ) on myogenesis in aging. We show that reprogramming the metabolism by TMZ treatment for 12 consecutive days stimulates myogenic gene expression in skeletal muscle of 22-month-old mice. Our data also reveal that TMZ increases the levels of mitochondrial proteins and stimulates the oxidative metabolism in aged muscles, this finding being in line with our previous observations in cachectic mice. Moreover, we show that, besides TMZ also other types of metabolic modulators (i.e., 5-Aminoimidazole-4-Carboxamide Ribofuranoside-AICAR) can stimulate differentiation of skeletal muscle progenitors in vitro. Overall, our results reveal that reprogramming the metabolism stimulates myogenesis while triggering mitochondrial proteins synthesis in vivo during aging. Together with the previously reported ability of TMZ to increase muscle strength in aged mice, these new data suggest an interesting non-invasive therapeutic strategy which could contribute to improving muscle quality and neuromuscular communication in the elderly, and counteracting sarcopenia

Review on the effects of physical activity on body composition and shape in people with down syndrome

People with Down Syndrome (DS) are often characterized by overweight or obesity and result to be less active than their peers. Both overweight/obesity and physical inactivity are considered important risk factors for health, thus augmenting mortality risk. World Health Organization recommends different training programmes for health benefits in different age ranges of general population. Effects of physical activity may be even more important in preventing health consequences in people with DS. In this context, we conducted a literature search of original articles, published between May 2010 and May 2020, on the effects of physical activity on body shape, body composition and bone quality in people with DS. We found twelve articles from all the continents, investigating the effects of different types of physical activity on body fat and lean masses, bone composition and anthropometry. In sum, the included studies reported improvements in body composition (with augmented lean mass and reduced fat mass), body size (with lower weight, waist circumference and BMI) and bone quality (in terms of bone mineral content and/or bone mineral density). In particular, body composition improves after conditioning and plyometric jumps training program, 2-wheel bicycle training, whole body vibration and swimming. Body shape is significantly improved by bicycle training, interval training and swimming. Finally, bone quality shows positive results after conditioning and plyometric jumps training program, whole body vibration and weight bearing exercise. Although different types of physical activity are investigated in people with DS, however the best training programme for this population is not clear. So future studies may focus on the comparison or combination of different types of physical activity to assess which one could maximize benefits

Traumatic experiences in childhood and adolescence: a meta-analysis of prospective studies assessing risk for psychosis

Evidence of the association between traumatic experiences and psychosis are uncertain with respect to temporal order, clinical outcomes and the role of the age and genetic liability. The aim of the present meta-analysis was to explore the temporal relationship between the development of psychosis and traumatic exposure using prospective studies and to examine the role of moderation factors on overall effect sizes. Studies were identified by searching Embase-Ovid, PsycINFO (EBSCO), Pubmed, Scopus, Web of Science databases, and yielded an initial total of 9016 papers, leaving finally 23 after the screening process. Three sets of meta-analyses estimated the risk of developing psychotic experiences or full clinical psychosis by having experienced maltreatment by an adult or bullying by peers or parental death, using the random-effects model. Bullying by peers (OR = 2.28 [1.64, 4.34]), maltreatment by an adult (OR = 2.20 [1.72, 2.81]) and parental death (OR = 1.24 [1.06, 1.44]) all increased the risk of psychosis. Moderator analysis showed that negative effects of bullying were detected especially in those with genetic liability for psychosis and exposure to multiple trauma types; studies with higher prevalence of males showed a stronger risk for those exposed to parental death. No significant meta-regression was found between the risk of developing a full clinical psychosis or a psychotic experience. Lack of studies hampered the results about the age of trauma occurrence. The cumulative effect of being bullied from peers and experiencing other adversities during childhood and/or adolescence, together with genetic liability for psychosis, appears to confer the highest risk for developing psychotic symptoms later in life

Evidence for Thermally Activated Spontaneous Fluxoid Formation in Superconducting Thin-Film Rings

We have observed spontaneous fluxoid generation in thin-film rings of the amorphous superconductor Mo$_3$Si, cooled through the normal-superconducting transition, as a function of quench rate and externally applied magnetic field, using a variable sample temperature scanning SQUID microscope. Our results can be explained using a model of freezout of thermally activated fluxoids, mediated by the transport of bulk vortices across the ring walls. This mechanism is complementary to a mechanism proposed by Kibble and Zurek, which only relies on causality to produce a freezout of order parameter fluctuations.Comment: 4 pages, 3 figure