Black box vs gray box: Comparing GAP and GPrep-DFTB for ruthenium and ruthenium oxide.

The increasing popularity of machine learning (ML) approaches in computational modeling, most prominently ML interatomic potentials, opened possibilities that were unthinkable only a few years ago-structure and dynamics for systems up to many thousands of atoms at an ab initio level of accuracy. Strictly referring to ML interatomic potentials, however, a number of modeling applications are out of reach, specifically those that require explicit electronic structure. Hybrid ("gray box") models based on, e.g., approximate, semi-empirical ab initio electronic structure with the aid of some ML components offer a convenient synthesis that allows us to treat all aspects of a certain physical system on the same footing without targeting a separate ML model for each property. Here, we compare one of these [Density Functional Tight Binding with a Gaussian Process Regression repulsive potential (GPrep-DFTB)] with its fully "black box" counterpart, the Gaussian approximation potential, by evaluating performance in terms of accuracy, extrapolation power, and data efficiency for the metallic Ru and oxide RuO2 systems, given exactly the same training set. The accuracy with respect to the training set or similar chemical motifs turns out to be comparable. GPrep-DFTB is, however, slightly more data efficient. The robustness of GPRep-DFTB in terms of extrapolation power is much less clear-cut for the binary system than for the pristine system, most likely due to imperfections in the electronic parametrization.

Endometrial safety, overall safety and tolerability of transdermal continuous combined hormone replacement therapy over 96 weeks: a randomized open-label study.

OBJECTIVES: To establish whether transdermal continuous hormone replacement therapy (HRT) with estrogen/progestogen provides adequate long-term endometrial protection in postmenopausal women over a period of 96 weeks. METHODS: This multicenter, randomized, open-label, parallel-group study evaluated the endometrial effects and overall safety and tolerability of a transdermal matrix patch delivering estradiol (E2) 50 microg/day and norethisterone acetate (NETA) 140 microg/day (Estalis; patches applied twice weekly without intermediate breaks) and a once-daily oral comparator (Kliogest; one tablet containing E2 2 mg/NETA 1 mg) in postmenopausal women. A total of 406 women with an intact uterus, aged 44-69 years, were randomized in the 48-week core phase of the study, and 239 continued into the 48-week extension phase. Subjects were randomized in the ratio 3 : 1 to transdermal or oral E2/NETA treatment. RESULTS: No cases of endometrial hyperplasia or endometrial cancer were reported with either treatment during the core or extension phase. Both treatments were generally well tolerated, with most adverse events (>90%) being mild to moderate, although minor differences in the tolerability profile were observed between treatments. CONCLUSIONS: Continuous combined transdermal HRT with E2/NETA shows no evidence of an increased endometrial hyperplasia or endometrial cancer risk over a 96-week period.

Optically probing spin and charge interactions in a tunable artificial molecule.

We optically probe and electrically control a single artificial molecule containing a well defined number of electrons. Charge and spin dependent interdot quantum couplings are probed optically by adding a single electron-hole pair and detecting the emission from negatively charged exciton states. Coulomb- and Pauli-blockade effects are directly observed, and tunnel coupling and electrostatic charging energies are independently measured. The interdot quantum coupling is shown to be mediated by electron tunneling. Our results are in excellent accord with calculations that provide a complete picture of negative excitons and few-electron states in quantum dot molecules.

MRI of the brain and cervical spinal cord in rhizomelic chondrodysplasia punctata.

BACKGROUND: The classic rhizomelic chondrodysplasia punctata (RCDP) phenotype involves a typical facial appearance, cataracts, skeletal dysplasia causing disproportionate somatic growth failure, microcephaly, and severe psychomotor defects. Biochemical abnormalities include impaired plasmalogen biosynthesis in all forms of RCDP and accumulation of phytanic acid in RCDP type 1. A subset of patients has a milder clinical and biochemical phenotype, with less severe neurologic impairment and an incomplete deficiency in plasmalogens. The impact of plasmalogen deficiency on neurologic function is severe, causing spasticity and mental defects, but its pathomechanism is still unknown. The authors specifically focused on myelination because myelin is rich in ethanolamine plasmalogens. OBJECTIVE: To define the neuroimaging characteristics of the genetic peroxisomal disorder RCDP. METHODS: Twenty-one MR images of the brain and cervical spine of 11 patients were evaluated and correlated with neurologic and biochemical profiles. RESULTS: No abnormalities on MRI were seen in the patients with a mild phenotype of RCDP, whereas delayed myelination, ventricular enlargement and increased subarachnoidal spaces, supratentorial myelin abnormalities, and cerebellar atrophy were observed in patients with the severe phenotype of both RCDP type 1 and 3. The severity of both the MRI abnormalities and the clinical phenotype is correlated with the plasmalogen level. CONCLUSIONS: The severe phenotype of rhizomelic chondrodysplasia punctata (RCDP) is accompanied by a specific pattern of both developmental and regressive MRI abnormalities. Plasmalogen levels seem to play an important role in the pathophysiology of CNS abnormalities in RCDP. Increased phytanic acid appears not to be the cause of cerebellar atrophy.

Hormone replacement therapy and breast density changes.

OBJECTIVES: To compare the incidence of increased breast density and tenderness in postmenopausal women associated with transdermal (Estalis/Combipatch), Novartis, Basel, Switzerland) and oral (Kliogest), Schering AG, Berlin, Germany) hormone replacement therapy (HRT). METHODS: A total of 202 postmenopausal women were randomized to transdermal or oral HRT. Mammograms obtained at study entry and after 1 year of treatment were assessed for percent breast density by means of the digital segmentation and thresholding technique. Breast tenderness was assessed at each study visit. RESULTS: The mean breast density by ANCOVA after adjusting for screening value at study end was significantly lower for women using Estalis (38.4%, standard error 0.9%) compared with Kliogest (46.9%, standard error 1.5%) (p<0.0001). Significantly fewer women using transdermal HRT had an increase in mammographic breast density or breast tenderness compared to oral HRT. Of the women using transdermal HRT, 39.1% had no change in breast density compared to 15.7% for women using oral HRT. Only 4% of women using transdermal HRT had a marked increase in density (>25%) compared to 15.7% of women using oral HRT. Overall, 36.0% of patients in the transdermal group reported breast tenderness at some point during the 1-year study, compared with 57.6% in the oral HRT group (p=0.0002). CONCLUSION: Transdermal HRT use is associated with a significantly lower incidence of increased mammographic breast density and breast tenderness compared with oral HRT.

[Diagnostic image (163). A mentally retarded girl with progressive vomiting. Trichobezoar]. / Diagnose in beeld (163). Een verstandelijk gehandicapt meisje met progressief braken. Trichobezoar.

An 11-year-old girl presented with progressive vomiting and weight loss. Physical examination revealed a large mass in the upper abdomen due to a large trichobezoar in the stomach.

Signatures of beta-peptide unfolding in two-dimensional vibrational echo spectroscopy: a simulation study.

An ensemble of exciton Hamiltonians for the amide-I band of the folded and unfolded states of a helical beta-heptapeptide is generated using a molecular dynamics (MD) simulation. The correlated fluctuations of its parameters and their signatures in two-dimensional (2D) vibrational echo spectroscopy are computed. This technique uses infrared pulse sequences to provide ultrafast snapshots of molecular structural fluctuations, in analogy with multidimensional NMR. The present study demonstrates that, by combining a method of calculating the vibrational Hamiltonian from MD snapshots and the nonlinear exciton equations (NEE), it may be possible to simulate realistic multidimensional IR spectra of chemically and biologically interesting systems.

Characterization of NMR relaxation-active motions of a partially folded A-state analogue of ubiquitin.

The dominant dynamics of a partially folded A-state analogue of ubiquitin that give rise to NMR 15N spin relaxation have been investigated using molecular dynamics (MD) computer simulations and reorientational quasiharmonic analysis. Starting from the X-ray structure of native ubiquitin with a protonation state corresponding to a low pH, the A-state analogue was generated by a MD simulation of a total length of 33 ns in a 60%/40% methanol/water mixture using a variable temperature scheme to control and speed up the structural transformation. The N-terminal half of the A-state analogue consists of loosely coupled native-like secondary structural elements, while the C-terminal half is mostly irregular in structure. Analysis of dipolar N-H backbone correlation functions reveals reorientational amplitudes and time-scale distributions that are comparable to those observed experimentally. Thus, the trajectory provides a realistic picture of a partially folded protein that can be used for gaining a better understanding of the various types of reorientational motions that are manifested in spin-relaxation parameters of partially folded systems. For this purpose, a reorientational quasiharmonic reorientational analysis was performed on the final 5 ns of the trajectory of the A-state analogue, and for comparison on a 5 ns trajectory of native ubiquitin. The largest amplitude reorientational modes show a markedly distinct behavior for the two states. While for native ubiquitin, such motions have a more local character involving loops and the C-terminal end of the polypeptide chain, the A-state analogue shows highly collective motions in the nanosecond time-scale range corresponding to larger-scale movements between different segments. Changes in reorientational backbone entropy between the A-state analogue and the native state of ubiquitin, which were computed from the reorientational quasiharmonic analyses, are found to depend significantly on motional correlation effects.

[Spondylodiscitis in 3 children; differential diagnosis and treatment]. / (Spondylo)discitis bij 3 kinderen; differentiaaldiagnose en behandeling.

Three children, a 4.5-year-old boy and two girls aged 21 months and 10 years respectively, had for several weeks to months experienced lower back pain or walking problems, two of them had an elevated sedimentation and leucocytosis. The MRI scan revealed a narrowing of the lumbal disk. Furthermore, in the case of the 10-year-old girl, Staphylococcus lugdunensis was cultured from the puncture material of the disk. After treatment she continued to experience intermittent complaints of back pain; the other children made a complete recovery. (Spondylo)discitis must be differentiated from vertebral osteomyelitis. In the case of (spondylo)discitis, immobilising the spine with a corset is the mainstay of treatment. Antibiotics are only indicated when osteomyelitis cannot be excluded. Generally, the prognosis is good.

[Chorea subsequent to acute rheumatic fever in a 9-year-old girl]. / Chorea op basis van acuut reuma bij een 9-jarig meisje.

A nine-year-old girl had acute choreatic symptoms in her face and limbs, after a throat infection 6 weeks previously. On auscultation of the heart a systolic murmur was found and echocardiography showed mitral valve incompetence. There was a positive anti-deoxyribonuclease B titre in the serum, providing evidence of a previously contracted streptococcal infection. Both chorea and acquired carditis are major criteria for the diagnosis of acute rheumatic fever. The course was characterized--as it usually is--by spontaneous, gradual resolution of the symptoms. Protracted penicillin prophylaxis is indicated to prevent recurrence of acute rheumatic fever and cardiac valvular damage.

Hydrolase activity of 150 Malassezia furfur isolates of different clinical origin.

Apart from pityriasis versicolor, Malassezia furfur is thought to play a significant role in the pathogenesis of seborrhoic eczema and Malassezia folliculitis. However, it has not been clarified whether in addition to host factors (e.g. immune status, greasy skin), yeast-dependent activities are responsible for manifestation of the disease. In this context interstrain variability of hydrolase activity of Malassezia isolates might be significant. For determination of hydrolase activity, washed yeast suspension was applied to selective agar for pathogenic fungi containing 8% (v/v) Tween 80 or Tween 60 and was incubated at 37 degrees C for 10 days. Growth was accompanied by formation of a dense white zone around the colony, in which free fatty acids corresponding to Tween 80 (C18:1) or Tween 60 (16:0, 18:0) were demonstrated by means of thin layer and gas chromatography. Thus, this phenomenon is a parameter for yeast-dependent hydrolysis of Tween 80 and Tween 60. Considering different growth behaviour, a "hydrolase zone' (H2) was determined using the quotient colony diameter/(ring+colony) diameter in each of the 150 strains tested. Although no significant H2 variations were observed in strains of different clinical origin, the present study revealed that in addition to a known enzyme, which is located within the cell wall and/or membrane systems, these Malassezia isolates produce a very active hydrolase diffusing into the medium.

[A field study to determine dosages in computed tomography]. / Feldstudie zur Ermittlung von Dosiswerten bei der Computertomographie.

122 CT scanners were studied in order to determine close values free in air on the axis of rotation during the most common types of examination. In addition, other exposure parameters were collected, which may be important in relation to dose to patients. The results showed a surprising variation in the dose values of CT examinations. It is concluded that it is not possible to estimate patient exposure reliably by using the information on exposure parameters supplied by the operator.