Logical inference approach to relativistic quantum mechanics: derivation of the Klein-Gordon equation

The logical inference approach to quantum theory, proposed earlier [Ann. Phys. 347 (2014) 45-73], is considered in a relativistic setting. It is shown that the Klein-Gordon equation for a massive, charged, and spinless particle derives from the combination of the requirements that the space-time data collected by probing the particle is obtained from the most robust experiment and that on average, the classical relativistic equation of motion of a particle holds

Photo-induced magnetization enhancement in two-dimensional weakly anisotropic Heisenberg magnets

By comparing the photo-induced magnetization dynamics in simple layered systems we show how light-induced modifications of the magnetic anisotropy directly enhance the magnetization. It is observed that the spin precession in (CH3NH3)2CuCl4, initiated by a light pulse, increases in amplitude at the critical temperature TC. The phenomenon is related to the dependence of the critical temperature on the axial magnetic anisotropy. The present results underline the possibility and the importance of the optical modifications of the anisotropy, opening new paths toward the control of the magnetization state for ultrafast memories.Comment: 5 pages, 3 figures, supplementary info as SIr.pd

Про авторів

The persistence of intertidal mussel beds is governed by both biotic and abiotic processes. Many studies have shown that waves and currents are able to erode mussels from an intertidal mussel bed, but here it is demonstrated that in temperate regions ice action can be important as well. These findings result from a 27-month-long monitoring campaign on a mature intertidal mussel bed in the Dutch Wadden Sea. Daily camera observations revealed two periods in which significant erosion occurred. The first event occurred in a period during which the bed was covered by ice. Ice action resulted in an initial decrease of 19% in mussel covered area around the monitoring station. The losses were concentrated in three erosion hotspots of which the largest two were located close to the beds’ edge. Around these hotspots, up to 0.3 m high ridges of piled up mussels had formed, with the highest ridges located westward of these erosion gaps. The observed topographic changes support the view that the mechanism by which the bed was damaged was, at least partly, due to physical disturbance by scouring ice. Recovery of mussel cover was limited in the 19 months following the ice action event. Due to sedimentation and reorganization of the mussels, initial relief inside the mussel bed was reduced again and mussels spread out over a larger area. Height differences between uncovered parts and mussel covered parts increased as a result of sedimentation in mussel covered areas. Wave action during a storm period caused a further reduction in mussel cover. Especially areas that were previously elevated by ice action suffered from large losses. Wave erosion occurred during multiple wind events, causing initially small erosion gaps to expand outward and increase in extent. The results suggest a twofold impact of wave and ice action on mussel bed cover: firstly, by directly eroding mussels from mussel beds; secondly, by indirectly increasing the exposure of mussel beds to wave induced bed shear stresses

Phonon and crystal field excitations in geometrically frustrated rare earth titanates

The phonon and crystal field excitations in several rare earth titanate pyrochlores are investigated. Magnetic measurements on single crystals of Gd2Ti2O7, Tb2Ti2O7, Dy2Ti2O7 and Ho2Ti2O7 are used for characterization, while Raman spectroscopy and terahertz time domain spectroscopy are employed to probe the excitations of the materials. The lattice excitations are found to be analogous across the compounds over the whole temperature range investigated (295-4 K). The resulting full phononic characterization of the R2Ti2O7 pyrochlore structure is then used to identify crystal field excitations observed in the materials. Several crystal field excitations have been observed in Tb2Ti2O7 in Raman spectroscopy for the first time, among which all of the previously reported excitations. The presence of additional crystal field excitations, however, suggests the presence of two inequivalent Tb3+ sites in the low temperature structure. Furthermore, the crystal field level at approximately 13 cm-1 is found to be both Raman and dipole active, indicating broken inversion symmetry in the system and thus undermining its current symmetry interpretation. In addition, evidence is found for a significant crystal field-phonon coupling in Tb2Ti2O7. These findings call for a careful reassessment of the low temperature structure of Tb2Ti2O7, which may serve to improve its theoretical understanding.Comment: 13 pages, 7 figure

Psychoeducation for depression, anxiety and psychological distress: a meta-analysis

Abstract Background Given the high prevalence and burden associated with depression and anxiety disorders and the existence of treatment barriers, there is a clear need for brief, inexpensive and effective interventions such as passive psychoeducational interventions. There are no published meta-analyses of the effectiveness of passive psychoeducation in reducing symptoms of depression, anxiety or psychological distress. Methods Cochrane, PsycInfo and PubMed databases were searched in September 2008. Additional materials were obtained from reference lists. Papers describing passive psychoeducational interventions for depression, anxiety and psychological distress were included if the research design was a randomized controlled trial and incorporated an attention placebo, no intervention or waitlist comparison group. Results In total, 9010 abstracts were identified. Of these, five papers which described four research studies targeting passive psychoeducation for depression and psychological distress met the inclusion criteria. The pooled standardized-effect size (four studies, four comparisons) for reduced symptoms of depression and psychological distress at post-intervention was d = 0.20 (95% confidence interval: 0.01-0.40; Z = 2.04; P = 0.04; the number needed to treat: 9). Heterogeneity was not significant among the studies (I2 = 32.77, Q:4.46; P = 0.22). Conclusions Although it is commonly believed that psychoeducation interventions are ineffective, this meta-analysis revealed that brief passive psychoeducational interventions for depression and psychological distress can reduce symptoms. Brief passive psychoeducation interventions are easy to implement, can be applied immediately and are not expensive. They may offer a first-step intervention for those experiencing psychological distress or depression and might serve as an initial intervention in primary care or community models. The findings suggest that the quality of psychoeducation may be important

A Quantitative Exploration of Two Teachers with Contrasting Emotions: Intra-Individual Process Analyses of Physiology and Interpersonal Behavior

Although the association between teacher-student relations, teacher emotions, and burnout has been proven on a general level, we do not know the exact processes underlying these associations. Recently there has been a call for intra-individual process measures that assess what happens from moment-to-moment in class in order to better understand inter-individual differences in emotions and burnout between teachers. This paper explored the use of process measures of teachers’ heart rate and their interpersonal behavior during teaching. Our aim was to illustrate different ways of analyzing and combining physiological and observational time-series data and to explore their potential for understanding between-teacher differences. In this illustration, we focused on two teachers who represented contrasting cases in terms of their self-reported teaching-related emotions (i.e., anxiety and relaxation) and burnout. We discuss both univariate process analyses (i.e., trend, autocorrelation, stability) as well as state-of-the-art multivariate process analyses (i.e., cross-correlations, dynamic structural equation modeling). Results illustrate how the two teachers differed in the nature of their physiological responses, their interpersonal behavior, and the association between these two process measures over time. Along implications and suggestions for further research, it is discussed how the process-based, dynamic assessment of physiology and interpersonal behavior may ultimately help to understand differences in more general teaching-related emotions and burnout

Comprehensive analysis of T cell leukemia signals reveals heterogeneity in the PI3 kinase-Akt pathway and limitations of PI3 kinase inhibitors as monotherapy.

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic cancer. Poly-chemotherapy with cytotoxic and genotoxic drugs causes substantial toxicity and more specific therapies targeting the underlying molecular lesions are highly desired. Perturbed Ras signaling is prevalent in T-ALL and occurs via oncogenic RAS mutations or through overexpression of the Ras activator RasGRP1 in ~65% of T-ALL patients. Effective small molecule inhibitors for either target do not currently exist. Genetic and biochemical evidence link phosphoinositide 3-kinase (PI3K) signals to T-ALL, PI3Ks are activated by Ras-dependent and Ras-independent mechanisms, and potent PI3K inhibitors exist. Here we performed comprehensive analyses of PI3K-Akt signaling in T-ALL with a focus on class I PI3K. We developed a multiplex, multiparameter flow cytometry platform with pan- and isoform-specific PI3K inhibitors. We find that pan-PI3K and PI3K γ-specific inhibitors effectively block basal and cytokine-induced PI3K-Akt signals. Despite such inhibition, GDC0941 (pan-PI3K) or AS-605240 (PI3Kγ-specific) as single agents did not efficiently induce death in T-ALL cell lines. Combination of GDC0941 with AS-605240, maximally targeting all p110 isoforms, exhibited potent synergistic activity for clonal T-ALL lines in vitro, which motivated us to perform preclinical trials in mice. In contrast to clonal T-ALL lines, we used a T-ALL cancer model that recapitulates the multi-step pathogenesis and inter- and intra-tumoral genetic heterogeneity, a hallmark of advanced human cancers. We found that the combination of GDC0941 with AS-605240 fails in such trials. Our results reveal that PI3K inhibitors are a promising avenue for molecular therapy in T-ALL, but predict the requirement for methods that can resolve biochemical signals in heterogeneous cell populations so that combination therapy can be designed in a rational manner