Dependence of field-aligned electron precipitation on season, altitude and pitch angle

The occurrence of field-aligned 2.3 keV electron precipitation was examined by using data from more than 7500 orbits of the polar-orbiting satellite, OGO-4. The frequency of occurrence of field aligned precipitation was highest at actual pitch angles between 7 and 10 deg, being highest in the winter months, at highest satellite altitudes. Acceleration by a localized parallel electric field established by electrostatic charge layers is proposed to explain particle observations

Protons as the prime contributors to the storm time ring current

Following a large magnetic storm (17 June 1972), Explorer 45 measured the equatorial particle populations and magnetic field. Using data obtained during the symmetic recovery phase, it is shown that through a series of self-consistent calculations, the measured protons with energies from 1 to 872 keV, can account for the observed ring current magnetic effects within experimental uncertainities. This enables an upper limit to be set for the heavy ion contribution to the storm time ring current

Positronium reflection and positronium beams

Specular reflection of positronium, Ps was observed and that there is adequate intensity at higher energies to make further study worthwhile was established. The scattering appears to be restricted to the outermost surface with a mean free path of (0.75 + or - 0.15)A for Ps in LiF(100). With a greater intensity Ps beam one should see higher order diffraction beams as the result of the periodicity of the surface. Ps diffraction thus offers the possibility of being a novel and valuable probe to study the outermost surface and to study adsorbants on it. Two methods for producing Ps beams are described

Cancellation of probe effects in measurements of spin polarized momentum density by electron positron annihilation

Measurements of the two dimensional angular correlation of the electron-positron annihilation radiation have been done in the past to detect the momentum spin density and the Fermi surface. We point out that the momentum spin density and the Fermi Surface of ferromagnetic metals can be revealed within great detail owing to the large cancellation of the electron-positron matrix elements which in paramagnetic multiatomic systems plague the interpretation of the experiments. We prove our conjecture by calculating the momentum spin density and the Fermi surface of the half metal CrO2, who has received large attention due to its possible applications as spintronics material

Experimental study of the role of physicochemical surface processing on the IN ability of mineral dust particles

During the measurement campaign FROST 2 (FReezing Of duST 2), the Leipzig Aerosol Cloud Interaction Simulator (LACIS) was used to investigate the influence of various surface modifications on the ice nucleating ability of Arizona Test Dust (ATD) particles in the immersion freezing mode. The dust particles were exposed to sulfuric acid vapor, to water vapor with and without the addition of ammonia gas, and heat using a thermodenuder operating at 250 °C. Size selected, quasi monodisperse particles with a mobility diameter of 300 nm were fed into LACIS and droplets grew on these particles such that each droplet contained a single particle. Temperature dependent frozen fractions of these droplets were determined in a temperature range between −40 °C ≤T≤−28 °C. The pure ATD particles nucleated ice over a broad temperature range with their freezing behavior being separated into two freezing branches characterized through different slopes in the frozen fraction vs. temperature curves. Coating the ATD particles with sulfuric acid resulted in the particles' IN potential significantly decreasing in the first freezing branch (T>−35 °C) and a slight increase in the second branch (T≤−35 °C). The addition of water vapor after the sulfuric acid coating caused the disappearance of the first freezing branch and a strong reduction of the IN ability in the second freezing branch. The presence of ammonia gas during water vapor exposure had a negligible effect on the particles' IN ability compared to the effect of water vapor. Heating in the thermodenuder led to a decreased IN ability of the sulfuric acid coated particles for both branches but the additional heat did not or only slightly change the IN ability of the pure ATD and the water vapor exposed sulfuric acid coated particles. In other words, the combination of both sulfuric acid and water vapor being present is a main cause for the ice active surface features of the ATD particles being destroyed. A possible explanation could be the chemical transformation of ice active metal silicates to metal sulfates. The strongly enhanced reaction between sulfuric acid and dust in the presence of water vapor and the resulting significant reductions in IN potential are of importance for atmospheric ice cloud formation. Our findings suggest that the IN concentration can decrease by up to one order of magnitude for the conditions investigated

Towards an understanding of hole superconductivity

From the very beginning K. Alex M\"uller emphasized that the materials he and George Bednorz discovered in 1986 were $hole$ superconductors. Here I would like to share with him and others what I believe to be $the$ key reason for why high $T_c$ cuprates as well as all other superconductors are hole superconductors, which I only came to understand a few months ago. This paper is dedicated to Alex M\"uller on the occasion of his 90th birthday.Comment: Dedicated to Alex M\"uller on the Occasion of his 90th Birthday. arXiv admin note: text overlap with arXiv:1703.0977

Full potential LAPW calculation of electron momentum density and related properties of Li

Electron momentum density and Compton profiles in Lithium along $$,$$, and $$ directions are calculated using Full-Potential Linear Augmented Plane Wave basis within generalized gradient approximation. The profiles have been corrected for correlations with Lam-Platzman formulation using self-consistent charge density. The first and second derivatives of Compton profiles are studied to investigate the Fermi surface breaks. Decent agreement is observed between recent experimental and our calculated values. Our values for the derivatives are found to be in better agreement with experiments than earlier theoretical results. Two-photon momentum density and one- and two-dimensional angular correlation of positron annihilation radiation are also calculated within the same formalism and including the electron-positron enhancement factor.Comment: 11 pages, 7 figures TO appear in Physical Review

Street Code Adherence, Callous-Unemotional Traits and the Capacity of Violent Offending versus Non-Offending Urban Youth to Mentalize About Disrespect Murder

National statistics are not available on the proportion of violent juvenile offenses driven by the experience of being disrespected. However, the New York Police Department estimates that about 40% of the city\u27s shootings involve members of violent crews of 12 to 20 year olds with most of this gun violence driven by incidents of disrespect. Mentalization, defined as the ability to envision mental states (i.e., feelings, beliefs and intentions) in oneself and others, is viewed as underlying affect regulation, impulse control, self-monitoring, and the experience of self-agency, all of which are implicated in interpersonal violence (Fonagy, Gergely, Jurist, & Target, 2002). From a developmental psychodynamic perspective, the capacity to mentalize is seen as developing within the context of secure early attachment relationships via the process of caregiver affect attunement (Fonagy et al., 2002; Stern, 1985; Winnicott, 1963) with further scaffolding optimally provided by secure social contexts such as school and the wider socio-cultural environment (Twemlow, 2003). This mixed-methods pilot study investigated the extent and nature of breakdowns in mentalization in the context of street violence in a community sample (N = 18) of violent offending versus non-offending male adolescents from low-income New York City neighborhoods and the degree to which these breakdowns are shaped by level of street code adherence and callous-unemotional (CU) traits. Secondary analyses examined the relationship of CU traits with street code adherence and with the capacity to mentalize in the context of attachment relationships given the limited investigation of social-cultural and relational factors that may shape the development of CU traits. Self-report measures assessed participants\u27 level of street code adherence, CU traits and the capacity to mentalize in attachment relationships. Mentalizing capacity in the context of street violence was assessed through a semi-structured interview using movie clips of disrespect murders involving teenaged perpetrators that was coded for level of reflective function by an independent rater as well as analyzed qualitatively. Violent offenders presented with significantly lower overall mentalizing capacities (M = 3.30, SD = .67) than controls (M = 4.19, SD = .88), t (df) = -2.41, p = .03) in the context of street violence. Qualitatively, violent offenders exhibited more frequent and extensive breakdowns than controls when called upon to mentalize both the perpetrators\u27 and victims\u27 experiences ranging from a more limited affective repertoire to the complete collapse of mentalization and greater defensive distancing (e.g., yawning). A higher level of street code adherence was found to be moderately related to a lower capacity to mentalize in the context of street violence. A medium effect size was found for the relationship between higher levels of CU traits and lower capacity to mentalize the victim\u27s (though not the perpetrators) experience. While this latter finding was not statistically significant it is suggested that with a larger sample size this effect may be statistically significant. Lower mentalizing capacities in the context of attachment relationships were found to be associated with higher levels of street code adherence. From this perspective, individuals whose early attachment related experiences did not support the acquisition of adequate mentalizing capacities may be more drawn to the predictable yet organizing framework for interpersonal interactions provided by street code. Finally, a case study of one of the violent offender participants is presented to demonstrate how impoverished emotional responses among high CU and high street-code adhering youth may, in part, represent a turning off of emotions secondary to the trauma of community violence. Implications for the adaption of mentalization-based therapy for street code-invested violent youth are discussed

CALCULATION OF HIGHER HARMONICS TAKING INTO ACCOUNT OF ACTIVE RESISTANCES IN ELECTRIC

The paper discusses the method of using active resistance in the calculations of higher harmonics in electrical networks.В работе рассматривается методика использования активных сопротивлений в расчетах высших гармоник в электрических сетях

Genomic Profiling of Childhood Tumor Patient-Derived Xenograft Models to Enable Rational Clinical Trial Design.

Accelerating cures for children with cancer remains an immediate challenge as a result of extensive oncogenic heterogeneity between and within histologies, distinct molecular mechanisms evolving between diagnosis and relapsed disease, and limited therapeutic options. To systematically prioritize and rationally test novel agents in preclinical murine models, researchers within the Pediatric Preclinical Testing Consortium are continuously developing patient-derived xenografts (PDXs)-many of which are refractory to current standard-of-care treatments-from high-risk childhood cancers. Here, we genomically characterize 261 PDX models from 37 unique pediatric cancers; demonstrate faithful recapitulation of histologies and subtypes; and refine our understanding of relapsed disease. In addition, we use expression signatures to classify tumors for TP53 and NF1 pathway inactivation. We anticipate that these data will serve as a resource for pediatric oncology drug development and will guide rational clinical trial design for children with cancer