Magnon spectrum of the helimagnetic insulator Cu2OSeO3.

Complex low-temperature-ordered states in chiral magnets are typically governed by a competition between multiple magnetic interactions. The chiral-lattice multiferroic Cu2OSeO3 became the first insulating helimagnetic material in which a long-range order of topologically stable spin vortices known as skyrmions was established. Here we employ state-of-the-art inelastic neutron scattering to comprehend the full three-dimensional spin-excitation spectrum of Cu2OSeO3 over a broad range of energies. Distinct types of high- and low-energy dispersive magnon modes separated by an extensive energy gap are observed in excellent agreement with the previously suggested microscopic theory based on a model of entangled Cu4 tetrahedra. The comparison of our neutron spectroscopy data with model spin-dynamical calculations based on these theoretical proposals enables an accurate quantitative verification of the fundamental magnetic interactions in Cu2OSeO3 that are essential for understanding its abundant low-temperature magnetically ordered phases.

Randomized clinical trials in children--ethical and methodological issues.

Randomization is an internationally accepted methodological tool used to perform sound clinical research. To ensure the clinical value of medical interventions, both evidence based medicine and new drug approvals require that randomized controlled trials (RCT) be conducted. Randomization prevents the manipulation of participant allocation and balances unknown confounders in a way no other method can. The gold standard RCT, however, is complex to conduct and requires significant financial and structural resources. In consequence, drug development and registration are primarily driven by the pharmaceutical industry. Within the field of pediatrics, we need high quality research tailored to children in order to reduce off-label use and to ensure that we expose children only to effective and, above all, safe drug treatments. The American and European regulatory authorities now offer programs to support such studies and clinical researchers and pharmaceutical industries are obliged to put them into practice in the best interest of the children. Issues relating to feasibility as well as ethical issues must be born in mind when planning RCTs in child populations. Obtaining informed assent from children in an adequate manner is one of several key elements. Moreover, it is essential to ensure equipoise before conducting a trial. Thus, issues relating to acceptability can be addressed and the discrimination of treatment groups within RCTs can be prevented. This narrative review addresses ethical and methodological aspects of RCTs in adults and especially in children and includes a quantitative analysis, which explores issues relating to the publication of RCTs.

[Optical coherence tomography for macula diagnostics. Review of methods and standardized application concentrating on diagnostic and therapy control of age-related macula degeneration]. / Optische Kohärenztomographie in der Makuladiagnostik. Ubersicht der Methode und standardisierte Anwendung--Diagnostik und Therapiekontrolle der altersbedingten Makuladegeneration.

BACKGROUND: Optical coherence tomography (OCT) has gained increasing relevance for follow-up after the treatment of macular diseases especially after anti-VEGF therapy. Therefore it seemed reasonable to develop standardized evaluation strategies and OCT examination guidelines for Stratus OCT III. MATERIALS AND METHODS: Basic guidelines for the Stratus OCT III examination of macular diseases were developed. The first part contains basic advice for the OCT examination with respect to the examiner, patients, image quality, movement artefacts, algorithms, archiving and interpretation of OCT images. The second part consists of the relevance and indications for OCT examination especially in age-related macular degeneration (AMD), subgroups of AMD and follow-up after treatment. The third part demonstrates a brief outlook on future developments, such as the digital integration method (DIM), which provides identical scan localization in follow-up and eliminates any movement artefacts. CONCLUSION: The application of standardized routine scanning and analysis protocols in Stratus OCT III for macular diseases and follow-up examinations provides an optimized, time-saving and comparable use of OCT. Therefore, the relevance and quality of OCT is increased for routine use in outpatient departments, hospitals and also for clinical studies.

Rich polymorphism of a rod-like liquid crystal (8CB) confined in two types of unidirectional nanopores.

We present a neutron and X-rays scattering study of the phase transitions of 4-n-octyl-4' -cyanobiphenyl (8CB) confined in unidirectional nanopores of porous alumina and porous silicon (PSi) membranes with an average diameter of 30 nm. Spatial confinement reveals a rich polymorphism, with at least four different low temperature phases in addition to the smectic A phase. The structural study as a function of thermal treatments and conditions of spatial confinement allows us to get insights into the formation of these phases and their relative stability. It gives the first description of the complete phase behavior of 8CB confined in PSi and provides a direct comparison with results obtained in bulk conditions and in similar geometric conditions of confinement but with reduced quenched disorder effects using alumina anopore membranes.

Preferred orientations and stability of medium length n-alkanes solidified in mesoporous silicon.

The n-alkanes C(16)H(34), C(17)H(36), C(19)H(40), and C(25)H(52) have been imbibed and solidified in mesoporous, crystalline silicon with a mean pore diameter of 10 nm. The structures and phase sequences have been determined by x-ray diffractometry. Apart from a reduction and the hysteresis of the melting-freezing transition, we find a set of six discrete orientation states ("domains") of the confined alkane crystals with respect to the lattice of the silicon host. The growth process responsible for the domain selection is interpreted as a nanoscale version of the Bridgman technique known from single-crystal growth. Oxidation of the pore walls leads to extrusion of the hydrocarbons upon crystallization, whereas the solidified n-alkanes investigated in nonoxidized, porous silicon are thermodynamically stable.

[Disseminated ischemic necrosis and livedo racemosa in a chronic dialysis patient with calciphylaxis]. / Disseminierte ischämische Nekrosen und Livedo racemosa bei einer Patientin mit Kalziphylaxie nach Langzeitdialyse.

Calciphylaxis occurred in a 40-year old female patient with end-stage renal failure. The patient developed livedo racemosa ("livedo reticularis") with painful skin necrosis and ulcers involving multiple areas of the hip and legs after 22 years of hemodialysis. X-ray-examinations revealed calcinosis of peripheral arteries, especially of the pelvis, thigh and hands, while histological examinations showed a fibrosis and calcinosis of small subcutaneous arteries. A generalized cutaneous microangiopathy could be demonstrated by transcutaneous oxygen pressure measurements. Laboratory data showed a moderate secondary hyperparathyroidism with mild elevation of calcium-phosphate product. In addition to the hemodialysis an attempt was made to improve the microcirculation by vasoactive drugs. The clinical course was characterized by slow healing of the ulcers and occurrence of new areas of cutaneous necrosis. Calciphylaxis is a rare late complication in patients with advanced, often end-stage renal failure. It has characteristic histopathological features and is frequently, but not always, associated with a disturbed calcium and phosphorus metabolism and mildly elevated levels of parathyroid hormone. Calciphylaxis is classified as a special type of metastatic calcinosis.

Capnography for detection of endobronchial migration of an endotracheal tube.

A patient is described in whom migration of an endotracheal tube into the right main bronchus was suspected when end-tidal carbon dioxide suddenly decreased from 28 to 22 mm Hg. Acute changes with migration of the endotracheal tube into the main bronchus were also studied in an animal experimental model. End-tidal carbon dioxide decreased and tracheal (inflation) pressure increased, with no change in tidal volume. Arterial blood gases showed time-dependent decreases in pH and oxygen tension and an increase in carbon dioxide tension.

Porous-coated knee arthroplasty. A case report concerning bone ingrowth.

The area of bone-metal interaction in uncemented implants is regarded by many investigators as the key to the success or failure of the implant. The nature of the interaction is poorly understood because the zone is technically difficult to visualize and analyze. In order to test the power of modern imaging, analyzing, and metallurgical methods in this context, a well-functioning porous-coated knee prosthesis (tibial component) removed from the knee of a 65-year-old man was sectioned and examined by light microscopy, roentgenogram, scanning electron microscopy, and radiologic energy dispersive analysis. Independently, these methods demonstrated that the prosthesis was held in situ by collagenous tissue between and below the metal pellets of the prosthesis. Calcified bone did not appear to interact with the prosthesis and is probably not a major factor for prosthesis fixation. The various analytic methods described are suitable and sufficient for further exploration on a larger scale of the zone of bone-metal contact in cementless implants.

Mass spectrometer failure: an unusual cause.

A potentially serious problem is inherent in the current design of the mass spectrometer multiplex system. In spite of the filter on the sampling tube, foreign material can be aspirated into this tube, causing malfunction of the system. Prevention of this problem is discussed, and precautions are given.

Recognition of mixed anesthetic agents by mass spectrometer during anesthesia.

Anesthetic agents are sometimes added to the wrong vaporizer on an anesthesia machine. As a result, the vaporizer may deliver a mixture of anesthetic agents at concentrations inappropriate for use on a patient. However, untoward clinical complications related to vaporizers can be prevented with a time-shared mass spectrometer. This device accurately and rapidly indicates the gases and gas concentrations present in a vaporizer.

Ultrastructural characteristics and variations in human mucinous breast carcinomas.

Nineteen human mucinous breast carcinomas have been studied by electron microscopy in order to investigate the variations in the fine structure of this type of tumor. All the investigated tumors are characterized by a well-developed, rough endoplasmic reticulum and prominent Golgi complexes. The majority of tumor cells contain secretory granules. Approximately 50% (9/19) of the tumors have cytoplasmic dense core granules that are morphological identical to the neurosecretory granules found in APUD-cell derived tumors. Six out of the nine tumors react positively in a Grimelius staining for light microscopic argyrophilic granules. Two of the investigated breast carcinomas contain tonofilaments that are normally regarded as characteristic of squamous epithelium. It is concluded that mucinous breast carcinomas--that to this time have been regarded as a morphological homogenous group of tumors--are ultrastructurally characterized by heterogeneity.

Cytoplasmic inclusions in lymphocytes of chronic lymphocytic leukaemia. A report of 10 cases.

Peripheral blood from 90 CLL patients was examined by light-and electron-microscopy for the occurrence of crystalline inclusions in lymphocytes. Inclusions were demonstrated in 10 patients (11%). In these patients the inclusions were present in 5-45% of peripheral blood lymphocytes. In the light microscope the inclusions appeared as rectangular, unstained structures in May-Grünewald Giemsa and PAS stains. In the electron microscope the inclusions appeared as intracytoplasmic, completely partially membrane-bound bodies, which were often associated with dilated profiles of rough endoplasmic reticulum. The ultrastructure of the inclusions was granular. In immunofluorescence staining the inclusions were found to contain immunoglobulin of the same type and class as the surface membrane-bound immunoglobulin of the neoplastic lymphocytes, most frequently IgM-lambda. The lymphocytes of one case with kappa light chains at the cell surface membrane contained inclusions of the same ultrastructural morphology as those of the other cases with lambda light chains. The presence of inclusions was not associated with any specific clinical or prognostic features. the inclusions persisted during antileukaemic therapy. Their formation may be related to a dysfunction in the synthesis of surface membrane-bound immunoglobulins.

Metastatic melanoma with balloon cell changes: an electron microscopic study.

A case of metastatic balloon cell melanoma is presented. The balloon cells are ultrastructurally characterized by the presence of numerous cytoplasmic vacuoles and abnormal melanosomes, which confirm their melanocytic origin. The study supports the concept that the cytoplasmic vacuoles represent grossly dilated melanosomes. The value of electron microscopic examination is emphasized in order to distinguish these lesions from other malignant clear cell tumors.

A comparison of heat stress indices in a hot-humid environment.

The results of a study of nine physically fit young men performing moderate exercise under various levels of hot-humid conditions are reported. Environmental stress and physiological strain data from the total of 72 test sessions were collected and computed in terms of heat stress and heat strain indices. Single and multiple factor correlation coefficients were calculated on the basis of 11 stress indices versus 4 strain indices. Most of the empirical heat stress indices correlated best with the mean skin temperature, whereas the rational indices correlated best with heart rate and sweat loss. Because of its ease of use, the WGT or the CET index may be the best choice for preliminary industrial surveys in hot-humid environments. A simple and convenient nomogram was developed on the basis of the test data relating increase in heart rate to temperature, humidity, and air velocity.