Dissipative Majorana Quantum Wires.

In this paper, we formulate and quantitatively examine the effect of dissipation on topological systems. We use a specific model of Kitaev quantum wire with an onsite Ohmic dissipation and perform a numerically exact method to investigate the effect of dissipation on the topological features of the system (e.g., the Majorana edge mode) at zero temperature. We find that even though the topological phase is robust against weak dissipation as it is supposed to be, it will eventually be destroyed by sufficiently strong dissipation via either a continuous quantum phase transition or a crossover depending on the symmetry of the system. The dissipation-driven quantum criticality has also been discussed.

Cavernomas de tronco encefálico: presentación de 8 casos operados, análisis y revisión del estado del arte / Brainstem cavernous malformations: a series of 8 surgicalcases, analysis and state of the art review

Introducción: Las lesiones del tronco cerebral son uno de los mayores desafíos neuroquirúrgicos. Los angiomas cavernosos de esta localización son lesiones de comportamiento agresivo, con alta morbi-mortalidad asociada, donde el neurocirujano tiene la posibilidad de curar al paciente pero con un nivel de riesgo que hacen que la oportunidad de la cirugía se mantenga en debate. Material y Método: Análisis retrospectivo de 8 casos de cavernomas de tronco operados entre los años 2009-2013 con sus características clínicas, quirúrgicas y de seguimiento. Se realiza además una revisión reflexiva sobre la evolución del manejo de estas lesiones y del estado del arte a nivel en el concierto internacional. Resultados: Los 8 casos presentaron evoluciones inmediatas y mediatas favorables tras la cirugía. No hubo mortalidad ni empeoramiento del status neurológico en relación al estado preoperatorio en ninguno de los 8 casos. Tres de los pacientes de la serie fueron operados tras caer en una condición clínica crítica y son los que registran los mayores déficits durante el seguimiento. El análisis de la evolución del manejo de este tipo de lesiones a nivel mundial revela una tendencia hacia el manejo quirúrgico precoz en lesiones sintomáticas. Conclusiones: Los resultados de esta serie así como la evolución del estado del arte permiten concluir que en pacientes sintomáticos una cirugía precoz ofrece en general mejores expectativas que intervenciones tardías para lesiones relativamente superficiales.

Introduction: Brainstem lesions are a major neurosurgical challenge. Cavernous angiomas of this location are lesions of aggressive behavior, with high morbidity and mortality associated, where the neurosurgeon has the possibility to cure the patient but with a level of risk that makes that the surgery timing remains under debate. Material and Methods: A retrospective analysis of 8 brainstem cavernomas cases operated in the period 2009-2013 is presented whit its clinical, surgical and follow-up characteristics. A thoughtful review of the evolution of the management of these lesions and the state of art in the international level is also carried out. Results: All 8 patients presented immediate and mediate favorable changes after surgery. There was no mortality or worsening of the neurological condition in relation to the preoperative status in any of the 8 cases. 3 patients in this series underwent surgery after falling in a critical condition and are those who have the highest deficit in the follow-up. The analysis of the evolution of the worldwide management of these injuries reveals a trend towards early surgical management in symptomatic lesions. Conclusions: The results of this series as well as the evolution of the state of the art let us conclude that in symptomatic patients an early surgery offers overall better expectations than later interventions in relatively superficial lesions.

Soft superconducting gap in semiconductor Majorana nanowires.

We theoretically consider the ubiquitous soft gap measured in the tunneling conductance of semiconductor-superconductor hybrid structures, in which recently observed signatures of elusive Majorana bound states have created much excitement. We systematically study the effects of magnetic and nonmagnetic disorder, temperature, dissipative Cooper pair breaking, and interface inhomogeneity, which could lead to a soft gap. We find that interface inhomogeneity with moderate dissipation is the only viable mechanism that is consistent with the experimental observations. Our work indicates that improving the quality of the superconductor-semiconductor interface should result in a harder induced gap.

Easy-axis ferromagnetic chain on a metallic surface.

The phases and excitation spectrum of an easy-axis ferromagnetic chain of S = 1/2 magnetic impurities built on the top of a clean metallic surface are studied. As a function of the (Kondo) coupling to the metallic surface and at low temperatures, the spin chain exhibits a quantum phase transition from an Ising ferromagnetic phase with long-range order to a paramagnetic phase where quantum fluctuations destroy the magnetic order. In the paramagnetic phase, the system consists of a chain of Kondo singlets where the impurities are completely screened by the metallic host. In the ferromagnetic phase, the excitations above the Ising gap are damped magnons, with a finite lifetime arising due to the coupling to the substrate. We discuss the experimental consequences of our results to spin-polarized electron energy loss spectroscopy, and we finally analyze possible extensions to spin chains with S > 1/2.

Straight to the point: how people encode linear discontinuations

Spatial discontinuations, as those found in cities and buildings, are everyday events. But, how do we encode and classify such misalignments? This is the topic of this paper. Twenty participants were asked to classify a total of 51 icons showing an upward-moving line being misaligned to the right, left and straight down. The results show that subjects were very sensitive to slight discontinuations occurring to vertical lines and that there was not exact symmetry between the left and right axis, meaning that the pieces slightly misaligned to the left were encoded differently than those misaligned to the right.

Straight to the point: how people encode linear discontinuations

Spatial discontinuations, as those found in cities and buildings, are everyday events. But, how do we encode and classify such misalignments? This is the topic of this paper. Twenty participants were asked to classify a total of 51 icons showing an upward-moving line being misaligned to the right, left and straight down. The results show that subjects were very sensitive to slight discontinuations occurring to vertical lines and that there was not exact symmetry between the left and right axis, meaning that the pieces slightly misaligned to the left were encoded differently than those misaligned to the right.(AU)

Interplay of disorder and interaction in Majorana quantum wires.

We study the interplay between disorder and interaction in one-dimensional topological superconductors which carry localized Majorana zero-energy states. Using Abelian bosonization and the perturbative renormalization group approach, we obtain the renormalization group flow and the associated scaling dimensions of the parameters and identify the critical points of the low-energy theory. We predict a quantum phase transition from a topological superconducting phase to a nontopological localized phase, and obtain the phase boundary between these two phases as a function of the electron-electron interaction and the disorder strength in the nanowire. Based on an instanton analysis which incorporates the effect of disorder, we also identify a large regime of stability of the Majorana-carrying topological phase in the parameter space of the model.

Subliminal presentation of other faces (but not own face) primes behavioral and evoked cortical processing of empathy for pain.

Current research on empathy for pain emphasizes the overlap in the neural response between the first-hand experience of pain and its perception in others. However, recent studies suggest that the perception of the pain of others may reflect the processing of a threat or negative arousal rather than an automatic pro-social response. It can thus be suggested that pain processing of other-related, but not self-related, information could imply danger rather than empathy, due to the possible threat represented in the expressions of others (especially if associated with pain stimuli). To test this hypothesis, two experiments considering subliminal stimuli were designed. In Experiment 1, neutral and semantic pain expressions previously primed with own or other faces were presented to participants. When other-face priming was used, only the detection of semantic pain expressions was facilitated. In Experiment 2, pictures with pain and neutral scenarios previously used in ERP and fMRI research were used in a categorization task. Those pictures were primed with own or other faces following the same procedure as in Experiment 1 while ERPs were recorded. Early (N1) and late (P3) cortical responses between pain and no-pain were modulated only in the other-face priming condition. These results support the threat value of pain hypothesis and suggest the necessity for the inclusion of own- versus other-related information in future empathy for pain research.

Prenatal testosterone treatment alters LH and testosterone responsiveness to GnRH agonist in male sheep.

Although evidence is accumulating that prenatal testosterone (T) compromises reproductive function in the female, the effects of excess T in utero on the postnatal development of male reproductive function has not been studied. The aim of this study was to assess the influence of prenatal T excess on age-related changes in pituitary and gonadal responsiveness to GnRH in the male sheep. We used the GnRH agonist, leuprolide (10 microg/kg), as a pharmacologic challenge at 5, 10, 20 and 30 weeks of age. These time points correspond to early and late juvenile periods and the prepubertal and postpubertal periods of sexual development, respectively. LH and T were measured in blood samples collected before and after GnRH agonist administration. The area under the response curve (AUC) of LH increased progressively in both controls and prenatal T-treated males from 5 to 20 weeks of age (P<0.01). The LH responses in prenatal T-treated males were lower at 20 and 30 weeks of age compared to controls (P<0.05). AUC-T increased progressively in control males from 5 through 30 weeks of age and prenatal T-treated males from 5 to 20 weeks of age. The T response in prenatal T-treated males was higher at 20 weeks compared to controls of same age but similar to controls and prenatal T-treated males at 30 weeks of age (P <0.05). Our findings suggest that prenatal T treatment advances the developmental trajectory of gonadal responsiveness to GnRH in male offspring.

Prenatal testosterone treatment alters LH and testosterone responsiveness to GnRH agonist in male sheep

Although evidence is accumulating that prenatal testosterone (T) compromises reproductive function in the female, the effects of excess T in utero on the postnatal development of male reproductive function has not been studied. The aim of this study was to assess the influence of prenatal T excess on age-related changes in pituitary and gonadal responsiveness to GnRH in the male sheep. We used the GnRH agonist, leuprolide (10 µg/kg), as a pharmacologic challenge at 5, 10, 20 and 30 weeks of age. These time points correspond to early and late juvenile periods and the prepubertal and postpubertal periods of sexual development, respectively. LH and T were measured in blood samples collected before and after GnRH agonist administration. The area under the response curve (AUC) of LH increased progressively in both controls and prenatal T-treated males from 5 to 20 weeks of age (P<0.01). The LH responses in prenatal T-treated males were lower at 20 and 30 weeks of age compared to controls (P<0.05). AUC-T increased progressively in control males from 5 through 30 weeks of age and prenatal T-treated males from 5 to 20 weeks of age. The T response in prenatal T-treated males was higher at 20 weeks compared to controls of same age but similar to controls and prenatal T-treated males at 30 weeks of age (P <0.05). Our findings suggest that prenatal T treatment advances the developmental trajectory of gonadal responsiveness to GnRH in male offspring.

Neurotomía periférica selectiva en el tratamiento de la espasticidad discapacitante del niño y adolescente / Peripheral selective neurotomy in the treatment of the disabling spasticity in child and adolescent

Abbreviations PSN Peripheral Selective Neurotomy;SEF Spastic Equinus Foot;SHA Spastic Hip Adduction;SHW Spastic Hand-Wrist Introduction.PSN is a microsurgical partial section of motor branches whose aim is supress the monosinaptic tonic stretching reflex leading to reduction of harmful spasticity without excessive paresis, restoring the tonic agonist-antagonist balance in a limb segment.Aims. Assess the benefits of PSN for treatment of disabling spasticity in children and teenager population. Method.19 consecutive patients (68 por ciento males,age 5-23 ), were treated through PSN.10 patients had SEF or SHA, and 9 had SHW.The inclusion criteria were age of 4 years or more; focused disabling spasticity at least grade 2 in Ashworth Mod. Scale; failure of previous non-surgical therapies; duration of spasticity more than 2 years, positive response to the motor anaesthetic block test; no evidence of irreductible muscle contracture. The goals of surgery were to improve function, cosmetics and confort of the affected limb segment. Clinical evaluation of spasticity (Ashworth Modified Scale), articular mobility (Goniometry), Gait (Video and gait analysis), and Prehension (Functional 440 pts. Scale), were performed. Results.The postoperative follow-up period range from 1 to 18 months. Spasticity was reduced in all the muscles denervated. The triceps surae spasticity reduction in SEF patients remain stable over a follow-up period of 6-18 months. 7/9 SEF patients improved ankle active dorsiflexion, ½ SHA improved hip abduction, while a mean improvement of 31.3° in wrist supination and 28.7° in wrist extension was achieved in the SHW group. 8/9 SEF patients showed improvement in 1 or more of the following gait features: ankle dorsiflexion, length of step, gait speed, proximal kinematic segment performance. The prehension improved in 7 patients (78 por ciento).All SHW patients improved their confort and limb cosmetics. 3 patients 15 por ciento) had transient dysesthesia...

[Prenatal exposure to androgens as a factor of fetal programming]. / La exposición prenatal a andrógenos como factor de reprogramación fetal.

Both epidemiological and clinical evidence suggest a relationship between the prenatal environment and the risk of developing diseases during adulthood. The first observations about this relationship showed that prenatal growth retardation or stress conditions during fetal life were associated to cardiovascular, metabolic and other diseases in later life. However, not only those conditions may have lasting effects after birth. Growing evidence suggests that prenatal exposure to steroids (either of fetal or maternal origin) could be another source of prenatal programming with detrimental consequences during adulthood. We have recently demonstrated that pregnant women with polycystic ovary syndrome exhibit elevated androgen levels compared to normal pregnant women, which could provide an androgen excess for both female or male fetuses. We have further tested this hypothesis in an animal model of prenatal androgenization, finding that females born from androgenized mothers have a low birth weight and high insulin resistance, that starts at an early age. On the other hand, males have low testosterone and LH secretion in response to a GnRH analogue test compared to control males and alterations in seminal parameters. We therefore propose that our efforts should be directed to modify the hyperandrogenic intrauterine environment to reduce the potential development of reproductive and metabolic diseases during adulthood.

La exposición prenatal a andrógenos como factor de reprogramación fetal / Prenatal exposure to androgens as a factor of fetal programming

Both epidemiological and clinical evidence suggest a relationship between the prenatal environment and the risk of developing diseases during adulthood. The first observations about this relationship showed that prenatal growth retardation or stress conditions during fetal life were associated to cardiovascular, metabolic and other diseases in later life. However, not only those conditions may have lasting effects after birth. Growing evidence suggests that prenatal exposure to steroids (either of fetal or maternal origin) could be another source of prenatal programming with detrimental consequences during adulthood. We have recently demonstrated that pregnant women with polycystic ovary syndrome exhibit elevated androgen levels compared to normal pregnant women, which could provide an androgen excess for both female or male fetuses. We have further tested this hypothesis in an animal model of prenatal androgenization, finding that females born from androgenized mothers have a low birth weight and high insulin resistance, that starts at an early age. On the other hand, males have low testosterone and LH secretion in response to a GnRH analogue test compared to control males and alterations in seminal parameters. We therefore propose that our efforts should be directed to modify the hyperandrogenic intrauterine environment to reduce the potential development of reproductive and metabolic diseases during adulthood.

Postnatal developmental consequences of altered insulin sensitivity in female sheep treated prenatally with testosterone.

Prenatally testosterone (T)-treated female sheep exhibit ovarian and endocrinological features that resemble those of women with polycystic ovarian syndrome (PCOS), which include luteinizing hormone excess, polyfollicular ovaries, functional hyperandrogenism, and anovulation. In this study, we determined the developmental impact of prenatal T treatment on insulin sensitivity indexes (ISI), a variable that is affected in a majority of PCOS women. Pregnant ewes were treated with 60 mg testosterone propionate intramuscularly in cottonseed oil two times a week or vehicle [control (C)] from days 30 to 90 of gestation. T-females weighed less than C-females or males (P < 0.05) at birth and at 5 wk of age. T-females had an increased anogenital ratio. An intravenous glucose tolerance test followed by an insulin tolerance test conducted after an overnight fast at 5, 20, and 30 wk of age (n = 7-8/group) revealed that ISI were higher at 5 than 30 wk of age in C-females, reflective of a developing insulin resistance associated with puberty. T-females had higher basal insulin levels, higher fasting insulin-to-glucose ratio, and higher incremental area under the insulin curve to the glucose challenge. The ISI of T-females was similar to that of males. No differences in ISI were evident between groups at 20 and 30 wk of age. Mean basal plasma glucose concentrations and glucose disappearance and uptake did not differ between groups at any age. Our findings suggest that prenatal T treatment leads to offspring with reduced birth weight and impaired insulin sensitivity in early postnatal life.

Response to the gonadotropin releasing hormone agonist leuprolide in immature female sheep androgenized in utero.

Similar to women with Polycystic Ovary Syndrome (PCOS), female sheep treated prenatally with testosterone (T-females) are hypergonadotropic, exhibit neuroendocrine defects, multifollicular ovarian morphology, hyperinsulinemia and cycle defects. Hypergonadotropism and multifollicular morphology may in part be due to developmentally regulated increase in pituitary responsiveness to GnRH and may culminate in increased ovarian estradiol production. In this study, we utilized a GnRH agonist, leuprolide, to determine the developmental impact of prenatal testosterone exposure on pituitary-gonadal function and to establish if prenatal exposure produces changes in the reproductive axis similar to those described for women with PCOS. Eight control and eight T-females were injected intravenously with 0.1 microg of leuprolide acetate per kilogram of body weight at 5, 10 and 20 weeks of age. Blood samples were collected by means of an indwelling jugular vein catheter at 0, 3, 6, 9, 12, 18, 24, 30, 36, 42 and 48 hours after leuprolide. Area under the curve (AUC) of LH response to leuprolide increased progressively between the three ages studied (P<0.05). AUC of LH in T-females was higher than in control females of the same age at 5 and 10 weeks of age (P < 0.05), but similar at 20 weeks of age. AUC of estradiol response was lower at 10 but higher at 20 weeks of age in T-females compared to controls of the same age (P < 0.05). Our findings suggest that prenatal T treatment alters the pituitary and ovarian responsiveness in a manner comparable to that observed in women with PCOS.

Response to the gonadotropin releasing hormone agonist leuprolide in immature female sheep androgenized in utero

Similar to women with Polycystic Ovary Syndrome (PCOS), female sheep treated prenatally with testosterone (T-females) are hypergonadotropic, exhibit neuroendocrine defects, multifollicular ovarian morphology, hyperinsulinemia and cycle defects. Hypergonadotropism and multifollicular morphology may in part be due to developmentally regulated increase in pituitary responsiveness to GnRH and may culminate in increased ovarian estradiol production. In this study, we utilized a GnRH agonist, leuprolide, to determine the developmental impact of prenatal testosterone exposure on pituitary-gonadal function and to establish if prenatal exposure produces changes in the reproductive axis similar to those described for women with PCOS. Eight control and eight T-females were injected intravenously with 0.1 mg of leuprolide acetate per kilogram of body weight at 5, 10 and 20 weeks of age. Blood samples were collected by means of an indwelling jugular vein catheter at 0, 3, 6, 9, 12, 18, 24, 30, 36, 42 and 48 hours after leuprolide. Area under the curve (AUC) of LH response to leuprolide increased progressively between the three ages studied (P<0.05). AUC of LH in T-females was higher than in control females of the same age at 5 and 10 weeks of age (P<0.05), but similar at 20 weeks of age. AUC of estradiol response was lower at 10 but higher at 20 weeks of age in T-females compared to controls of the same age (P<0.05). Our findings suggest that prenatal T treatment alters the pituitary and ovarian responsiveness in a manner comparable to that observed in women with PCOS.

Secretory patterns of leptin and luteinizing hormone in food-restricted young female sheep.

Leptin, the product of the ob gene, has been proposed as a metabolic signal that regulates the secretion of GnRH/LH. This may be critical during prepubertal development to synchronize information about energy stores and the secretion of GnRH/LH. This study aimed to assess the effect of food restriction on the episodic secretion of leptin and LH in young female sheep. Five 20-week-old prepubertal females were fed a low-level diet for 10 weeks to maintain the body weight. Control females of the same age received food ad libitum. Blood samples were collected at 10-min intervals for six hours at 20, 26, and 30 weeks of age, and plasma leptin, LH, insulin and cortisol concentrations were measured. In the control group, no changes were found in pulsatile LH secretion characteristics. Mean LH concentrations and LH amplitude were lower in the food-restricted group than in the control group at 26 and 30 weeks of age. In the control group, pulsatile leptin secretion did not change. When compared to control lambs of the same age, the food-restricted group showed lower mean plasma leptin concentrations, pulse amplitude and plasma insulin levels, after 6 weeks of restriction (week 26), although by week 30, plasma leptin concentrations and plasma insulin rose to those of the control group. Leptin pulse frequency did not change, nor did mean plasma levels of insulin in the control group at any age studied. Mean plasma concentration of cortisol did not change within or between groups. These data suggest that plasma leptin concentrations may not be associated with the onset of puberty under regular feeding and natural photoperiod in lambs. Prolonged food restriction, however, induces metabolic adaptations that allow an increase of leptin during the final period, probably related to the development of some degree of insulin resistance.

Secretory Patterns of Leptin and Luteinizing Hormone in Food-Restricted Young Female Sheep

Leptin, the product of the ob gene, has been proposed as a metabolic signal that regulates the secretion of GnRH/LH. This may be critical during prepubertal development to synchronize information about energy stores and the secretion of GnRH/LH. This study aimed to assess the effect of food restriction on the episodic secretion of leptin and LH in young female sheep. Five 20-week-old prepubertal females were fed a low-level diet for 10 weeks to maintain the body weight. Control females of the same age received food ad libitum. Blood samples were collected at 10-min intervals for six hours at 20, 26, and 30 weeks of age, and plasma leptin, LH, insulin and cortisol concentrations were measured. In the control group, no changes were found in pulsatile LH secretion characteristics. Mean LH concentrations and LH amplitude were lower in the food-restricted group than in the control group at 26 and 30 weeks of age. In the control group, pulsatile leptin secretion did not change. When compared to control lambs of the same age, the food-restricted group showed lower mean plasma leptin concentrations, pulse amplitude and plasma insulin levels, after 6 weeks of restriction (week 26), although by week 30, plasma leptin concentrations and plasma insulin rose to those of the control group. Leptin pulse frequency did not change, nor did mean plasma levels of insulin in the control group at any age studied. Mean plasma concentration of cortisol did not change within or between groups. These data suggest that plasma leptin concentrations may not be associated with the onset of puberty under regular feeding and natural photoperiod in lambs. Prolonged food restriction, however, induces metabolic adaptations that allow an increase of leptin during the final period, probably related to the development of some degree of insulin resistance..