Solving the Christoffel equation: phase and group velocities

We provide christoffel, a Python tool for calculating direction-dependent phase velocities, polarization vectors, group velocities, power flow angles and enhancement factors based on the stiffness tensor of a solid. It is built in a modular way to allow for efficient and flexible calculations, and the freedom to select and combine results as desired. All derivatives are calculated analytically, which circumvents possible numerical sampling problems. GNUPlot scripts are provided for convenient visualization

Ab initio based thermal property predictions at a low cost : an error analysis

Ab initio calculations often do not straightforwardly yield the thermal properties of a material yet. It requires considerable computational efforts, for example, to predict the volumetric thermal expansion coefficient alpha(V) or the melting temperature T-m from first principles. An alternative is to use semiempirical approaches. They relate the experimental values to first-principles predictors via fits or approximative models. Before applying such methods, however, it is of paramount importance to be aware of the expected errors. We therefore quantify these errors at the density-functional theory level using the Perdew-Burke-Ernzerhof functional for several semiempirical approximations of alpha(V) and T-m, and compare them to the errors from fully ab initio methods, which are computationally more intensive. We base our conclusions on a benchmark set of 71 ground-state elemental crystals. For the thermal expansion coefficient, it appears that simple quasiharmonic theory, in combination with different approximations to the Gruneisen parameter, provides a similar overall accuracy as exhaustive first-principles phonon calculations. For the melting temperature, expensive ab initio molecular-dynamics simulations still outperform semiempirical methods

How to find and diagnose a CDG due to defective N-glycosylation

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A systematic review of interpersonal processes and their measurement within experience sampling studies of self-injurious thoughts and behaviours

Self-injurious thoughts and behaviours (SITBs) are a leading cause of death, and interpersonal processes (IPs) appear to play a role in SITBs. This systematic review synthesises the literature on IPs and SITBs in daily life and addresses four critical questions: (1) Which IPs have been assessed and how, (2) What is the relationship between IPs and SITBs in daily life?, (3) Do daily-life fluctuations in IPs differ between individuals with and without SITBs?, and (4) Do IPs relate differently to self-injurious thoughts than behaviours? Our review followed PRISMA guidelines and eligible literature was screened until 29 August 2023. We identified 52 Experience Sampling studies (34.62% daily-diary studies) of which most focused on IPs from suicide theories (e.g., thwarted belongingness) but largely used inconsistent operationalizations. Results from 35 studies investigating within-person associations were mixed. Based on 24 studies, whether individuals with and without SITBs differ in their interpersonal experiences remains unclear. Four studies have investigated whether IPs relate to the transition from thoughts to behaviours, but temporal models are needed to draw firm conclusions. Studies investigating IPs and SITBs in daily life are largely inconclusive. Psychometrically validated measures are warranted, and future daily-life studies would benefit from drawing on ideation-to-action frameworks

Helpers' self-assessment biases before and after helping skills training

Several studies have shown that therapists are generally biased concerning their performed helping skills, as compared to judges' ratings. As clients' ratings of therapists' performance are better predictors of psychotherapy effectiveness than judges' ratings, this study examined the validity and effectiveness of a helping skills training program at reducing novice helpers' self-enhancement biases concerning their helping skills, in comparison to their clients ratings. Helping skills were assessed by three objective measures (a knowledge multiple choice test, a video test and a role play), as well as by a self- and peer-reported questionnaire. In addition, some performed helping skills' correlates (relationship quality, session quality, and helpers' therapeutic attitudes) were assessed both by helpers and their simulated helpees. Seventy-two sophomores in psychology participated to this study, 37 being assigned to a 12-h helping skills training program, and 35 to a control group. Helpers were expected to assess the aforementioned performed helping skills and correlates as being better than their helpees' assessments at pretest, thus revealing a self-enhancement bias. At posttest, we expected that trained helpers would objectively exhibit better helping skills than untrained helpers while beginning to underestimate their performance, thus indexing a self-diminishment bias. In contrast, we hypothesized that untrained helpers would continue to overestimate their performance. Our hypotheses were only partly confirmed but results reflected a skilled-unaware pattern among trainees. Trained helpers went either from a pretest overestimation to a posttest equivalence (performed helping skills and performed therapeutic attitudes), or from a pretest equivalence to a posttest underestimation (performed session quality and performed therapeutic relationship), as compared to helpees' ratings. Results showed that trained helpers improved on all helping skills objective measures and that helpees' perceptions of their performance had increased at posttest. In conclusion, helping skills training leads helpers not only to improve their helping skills but also to have more doubts about their skills, two variables associated with psychotherapy outcome. Keywords: exploration helping skills, helping skillstwo variables associated with psychotherapy outcome

Xeroderma pigmentosum complementation group G associated with cockayne syndrome

Xeroderma pigmentosum (XP) and Cockayne syndrome (CS) are two rare inherited disorders with a clinical and cellular hypersensitivity to the UV component of the sunlight spectrum. Although the two traits are generally considered as clinically and genetically distinct entities, on the biochemical level a defect in the nucleotide excision-repair (NER) pathway is involved in both. Classical CS patients are primarily deficient in the preferential repair of DNA damage in actively transcribed genes, whereas in most XP patients the genetic defect affects both "preferential" and "overall" NER modalities. Here we report a genetic study of two unrelated, severely affected patients with the clinical characteristics of CS but with a biochemical defect typical of XP. By complementation analysis, using somatic cell fusion and nuclear microinjection of cloned repair genes, we assign these two patients to XP complementation group G, which previously was not associated with CS. This observation extends the earlier identification of two patients with a rare combined XP/CS phenotype within XP complementation groups B and D, respectively. It indicates that some mutations in at least three of the seven genes known to be involved in XP also can result in a picture of partial or even full-blown CS. We conclude that the syndromes XP and CS are biochemically closely related and may be part of a broader clinical disease spectrum. We suggest, as a possible molecular mechanism underlying this relation, that the XPGC repair gene has an additional vital function, as shown for some other NER genes.</p

A novel mutation and first report of dilated cardiomyopathy in ALG6-CDG (CDG-Ic): a case report

Congenital disorders of glycosylation (CDG) are an expanding group of inherited metabolic diseases with multisystem involvement. ALG6-CDG (CDGIc) is an endoplasmatic reticulum defect in N-glycan assembly. It is usually milder than PMM2-CDG (CDG-Ia) and so is its natural course. It is characterized by psychomotor retardation, seizures, ataxia, and hypotonia. In contrast to PMM2-CDG (CDGIa), there is no cerebellar hypoplasia. Cardiomyopathy has been reported in a few CDG types and in a number of patients with unexplained CDG. We report an 11 year old Saudi boy with severe psychomotor retardation, seizures, strabismus, inverted nipples, dilated cardiomyopathy, and a type 1 pattern of serum transferrin isoelectrofocusing. Phosphomannomutase and phosphomannose isomerase activities were normal in fibroblasts. Full gene sequencing of the ALG6 gene revealed a novel mutation namely c.482A>G (p.Y161C) and heterozygosity in the parents. This report highlights the importance to consider CDG in the differential diagnosis of unexplained cardiomyopathy