Correlated Persistent Tunneling Currents in Glasses

Low temperature properties of glasses are derived within a generalized tunneling model, considering the motion of charged particles on a closed path in a double-well potential. The presence of a magnetic induction field B violates the time reversal invariance due to the Aharonov-Bohm phase, and leads to flux periodic energy levels. At low temperature, this effect is shown to be strongly enhanced by dipole-dipole and elastic interactions between tunneling systems and becomes measurable. Thus, the recently observed strong sensitivity of the electric permittivity to weak magnetic fields can be explained. In addition, superimposed oscillations as a function of the magnetic field are predicted.Comment: 4 page

Deriving reference values for nerve conduction studies from existing data using mixture model clustering

Objective: to obtain locally valid reference values (RVs) from existing nerve conduction study (NCS) data.Methods: we used age, sex, height and limb temperature-based mixture model clustering (MMC) to identify normal and abnormal measurements on NCS data from two university hospitals. We compared MMC-derived RVs to published data; examined the effect of using different variables; validated MMC-derived RVs using independent data from 26 healthy control subjects and investigated their clinical applicability for the diagnosis of polyneuropathy.Results: MMC-derived RVs were similar to published RVs. Clustering can be achieved using only sex and age as variables. MMC is likely to yield reliable results with fewer abnormal than normal measurements and when the total number of measurements is at least 300. Measurements from healthy controls fell within the 95% MMC-derived prediction interval in 97.4% of cases.Conclusions: MMC can be used to obtain RVs from existing data, providing a locally valid, accurate reflection of the (ab)normality of an NCS result.Significance: MMC can be used to generate locally valid RVs for any test for which sufficient data are available.(1) (C) 2021 International Federation of Clinical Neurophysiology. Published by Elsevier B.V.Development and application of statistical models for medical scientific researc

Children’s depressive symptoms and their regulation of negative affect in response to vignette-depicted emotion-eliciting events

The present study examined the relationship between sub-clinical depressive symptoms and children's anticipated cognitive and behavioral reactions to two written vignettes depicting emotion-eliciting stressors (i.e., fight with one's best friend and failure at a roller blade contest). Participants (N = 244) ranging in age between 10 and 13 were presented each vignette and then asked to rate their anticipated utilization of each of seven emotion-regulation strategies (ERs), along with the anticipated mood enhancement effects of each strategy. In addition, ratings of participants' perceived coping efficacy to manage the stressful situation were collected. Results indicated that participants were more likely to endorse ERs for which they have greater confidence in their mood enhancement effects. Moreover, marked differences were observed between ratings for conceptually distinct cognitive ERs. Consistent with expectations, results revealed that participants displaying higher levels of depressive symptoms were more likely to endorse cognitive and behavioral ERs that are negative, passive, and/or avoidant in nature. Children's ratings of the anticipated mood enhancement effects of several ERs were inversely related to their level of depressive symptoms, as was their perceived self-efficacy to manage the stressor. © 2007 The International Society for the Study of Behavioural Development

Proposal of a principle cum scale analytical framework for analyzing agroecological development projects

Because agroecology has different meanings, it may be used in an arbitrary and potentially abusive way when deployed by development cooperation actors conceiving “agroecology-based” development projects. To make the appropriation of agroecology more transparent, we first review the recent attempts in academia to clarify the concept and identify two main trends: a principle-based agroecology and a series of different agroecologies. Based on a critical assessment of these attempts, we then propose a new framework to program, implement and analyze agroecological development projects: it distinguishes different agroecologies with their corresponding categories of principles and their scales of intervention. Further, we argue in favor of a specific category of methodological principles.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Children’s Feedback Preferences in Response to an Experimentally Manipulated Peer Evaluation Outcome: The Role of Depressive Symptoms

The present study examined the linkage between pre-adolescent children’s depressive symptoms and their preferences for receiving positive vs. negative feedback subsequent to being faced with an experimentally manipulated peer evaluation outcome in real time. Participants (n = 142) ages 10 to 13, played a computer contest based on the television show Survivor and were randomized to either a peer rejection (i.e., receiving the lowest total ‘likeability’ score from a group of peer-judges), a peer success (i.e., receiving the highest score), or a control peer evaluation condition. Children’s self-reported feedback preferences were then assessed. Results revealed that participants assigned to the negative evaluation outcome, relative to either the success or the control outcome, showed a significantly higher subsequent preference for negatively tuned feedback. Contrary to previous work and predictions derived from self-verification theory, children higher in depressive symptoms were only more likely to prefer negative feedback in response to the negative peer evaluation outcome. These effects for depression were not accounted for by either state mood at baseline or mood change in response to the feedback manipulation

Children’s coping with in vivo peer rejection: An experimental investigation

We examined children's behavioral coping in response to an in vivo peer rejection manipulation. Participants (N=186) ranging between 10 and 13 years of age, played a computer game based on the television show Survivor and were randomized to either peer rejection (i.e., being voted out of the game) or non-rejection control. During a five-min. post-feedback waiting period children's use of several behavioral coping strategies was assessed. Rejection elicited a marked shift toward more negative affect, but higher levels of perceived social competence attenuated the negative mood shift. Children higher in depressive symptoms were more likely to engage in passive and avoidant coping behavior. Types of coping were largely unaffected by gender and perceived social competence. Implications are discussed. © 2006 Springer Science+Business Media, LLC

Deficient sustained attention to response task and P300 characteristics in early Huntington’s disease

Evidence for the extent and nature of attentional impairment in premanifest and manifest Huntington’s disease (HD) is inconsistent. Understanding such impairments may help to better understand early functional changes in HD and could have consequences concerning care for HD patients. We investigated attentional control in both early and premanifest HD. We studied 17 early HD subjects (mean age: 51 years), 12 premanifest HD subjects (mean age: 43 years), and 15 healthy controls (mean age: 51 years), using the sustained attention to response task (SART), a simple Go/No-go test reflecting attentional and inhibitory processes through reaction time (RT) and error rates. Simultaneously recorded EEG yielded P300 amplitudes and latencies. The early HD group made more Go errors (p < 0.001) and reacted slower (p < 0.005) than the other groups. The RT pattern during the SART was remarkably different for early HD subjects compared to the other two groups (p < 0.005), apparent as significant post-error slowing. P300 data showed that for early HD the No-go amplitude was lower than for the other two groups (p < 0.05). Subjects with early HD showed a reduced capacity to effectively control attention. They proved unable to resume the task directly after having made an error, and need more time to return to pre-error performance levels. No attentional control deficits were found for the premanifest HD group

Особенности развития малого предпринимательства в Украине

В этой работе рассмотрена эволюция предпринимательства Украины на всех этапах ее общественной жизни, в том числе в период экономического кризиса в годы становления независимости. Отражены основные параметры отнесения предприятий к субъектам малого предпринимательства и их роль в развитии экономики государств.У цій роботі розглянута еволюція підприємництва України на всіх етапах її суспільного життя, зокрема в період економічної кризи в роки становлення незалежності. Відображені основні параметри віднесення підприємств до суб'єктів малого підприємництва і їх роль в розвитку економіки держав

Farmer experiences of Tiyeni’s ‘deep-bed farming’ conservation agriculture system in Malawi

In the context of increasing NGO interest in the capacity of conservation agriculture methods to support sustainable agriculture across sub-Saharan Africa, this paper explores the experiences of farmers (n = 111) adopting the Tiyeni NGO’s deep-bed farming (DBF) system in northern Malawi. The results of a field survey suggest that whilst DBF delivers significant livelihood benefits for farmers relative to traditional techniques (a factor arguably driving its rapid spontaneous adoption throughout the area), some asset-poor farmers are unable to sustain DBF due to its labor demands. We argue that to widen its beneficial impacts in a manner that can be sustained, there is a need for Tiyeni’s DBF to be less prescriptive and more adaptive to specific social-ecological contexts

Retinoic Acid Signalling and the Control of Meiotic Entry in the Human Fetal Gonad

The development of mammalian fetal germ cells along oogenic or spermatogenic fate trajectories is dictated by signals from the surrounding gonadal environment. Germ cells in the fetal testis enter mitotic arrest, whilst those in the fetal ovary undergo sex-specific entry into meiosis, the initiation of which is thought to be mediated by selective exposure of fetal ovarian germ cells to mesonephros-derived retinoic acid (RA). Aspects of this model are hard to reconcile with the spatiotemporal pattern of germ cell differentiation in the human fetal ovary, however. We have therefore examined the expression of components of the RA synthesis, metabolism and signalling pathways, and their downstream effectors and inhibitors in germ cells around the time of the initiation of meiosis in the human fetal gonad. Expression of the three RA-synthesising enzymes, ALDH1A1, 2 and 3 in the fetal ovary and testis was equal to or greater than that in the mesonephros at 8–9 weeks gestation, indicating an intrinsic capacity within the gonad to synthesise RA. Using immunohistochemistry to detect RA receptors RARα, β and RXRα, we find germ cells to be the predominant target of RA signalling in the fetal human ovary, but also reveal widespread receptor nuclear localization indicative of signalling in the testis, suggesting that human fetal testicular germ cells are not efficiently shielded from RA by the action of the RA-metabolising enzyme CYP26B1. Consistent with this, expression of CYP26B1 was greater in the human fetal ovary than testis, although the sexually-dimorphic expression patterns of the germ cell-intrinsic regulators of meiotic initiation, STRA8 and NANOS2, appear conserved. Finally, we demonstrate that RA induces a two-fold increase in STRA8 expression in cultures of human fetal testis, but is not sufficient to cause widespread meiosis-associated gene expression. Together, these data indicate that while local production of RA within the fetal ovary may be important in regulating the onset of meiosis in the human fetal ovary, mechanisms other than CYP26B1-mediated metabolism of RA may exist to inhibit the entry of germ cells into meiosis in the human fetal testis