The correct measurement of oxygen saturation at high altitude.

BACKGROUND: Compared to measurements at sea level, measurement of oxygen saturation by pulse oximetry (SpO2) at altitude differs fundamentally because of the cyclical course of SpO2, caused by periodic breathing. Therefore, the determination of a representative SpO2 value is difficult. In the literature, recommendations for a standardized measurement procedure are missing; different studies measure SpO2 in different ways. KEY QUESTION: Does the visually determined SpO2 value correlate with the actual average of the measurement interval? METHODS: Four participants of an expedition (6013 m; Pakistan), familiar with pulse oximetry at altitude, wrote down the representative value of the measurement interval of 3 min (SpO2visual) according to their individual observation. The used pulse oximeter saved the value for SpO2 every 4 s. Based on this, the calculated mean (SpO2memory) was compared to SpO2visual after finishing the expedition (128 measurements > 2500 m). RESULTS: The spread of the single values within the measurement interval is high (in single cases up to 17%-points) in case of insufficient acclimatization. With increasing acclimatization, the measured values stabilize. SpO2visual differs only marginally (- 0.4%-points; ± 0.8) compared to SpO2memory. CONCLUSIONS: The correct pulse oximetric determination of SpO2 at high altitude requires a standardized measurement procedure; the investigator is familiar and trained. Anyway, the measurements have to be done in the continuous mode of the pulse oximeter over a sufficient timeframe (3 SpO2-fluctuation cycles; 2-3 min). We recommend to record the maximum and the minimum value of the measurement interval and to use a pulse oximeter device with memory function.

[Prehospital application of tourniquets for life-threatening extremity hemorrhage : Systematic review of literature]. / Prähospitale Anwendung von Tourniquets bei lebensbedrohlichen Extremitätenblutungen : Eine systematische Übersichtsarbeit.

INTRODUCTION: The effectiveness of a tourniquet in the case of life-threatening hemorrhages of the extremities is well recognized and led to the recommendations on "Tourniquet" of the German Society of Anaesthesiology and Intensive Care (DGAI) in 2016. The aim of this systematic review was to re-evaluate the current medical literature in relation to the published DGAI recommendations. MATERIAL AND METHODS: Based on the analysis of all studies published from January 2015 until January 2018 in the PubMed databases, the publicized recommendations for action on "Tourniquet" of the DGAI were critically re-evaluated. For this purpose, 17 questions on 6 subjects were formulated in advance. The systematic review followed the PRISMA recommendations and is registered in PROSPERO (International prospective register of systematic reviews, Reg.-ID: CRD42018091528). RESULTS: Of the 284 studies identified with the keywords tourniquet and trauma in the period from January 2015 to January 2018 in PubMed, 50 original papers discussing the prehospital application of tourniquet for life-threatening hemorrhage of the extremities were included. The overall level of evidence is low. No article addressed any of the formulated questions with a prospective randomized interventional study. Scientific deductions could be found only in an indirect way in a descriptive manner. CONCLUSION: The 50 original articles included in this qualitative, systematic review revealed that the recommendations "Tourniquet" of the DGAI published in 2016 are mostly still up to date despite an inhomogeneous study situation. A deviation occurred in the conversion of a tourniquet but due to the short prehospital treatment time in the civilian setting this is of little importance; however, in the future a strict distinction should be made between tourniquets which were placed for tactical reasons and those placed as a medical necessity.

Conceptual design of the time-of-flight backscattering spectrometer, MIRACLES, at the European Spallation Source.

In this work, we present the conceptual design of the backscattering time-of-flight spectrometer MIRACLES approved for construction at the long-pulse European Spallation Source (ESS). MIRACLES's unparalleled combination of variable resolution, high flux, extended energy, and momentum transfer (0.2-6 Å(-1)) ranges will open new avenues for neutron backscattering spectroscopy. Its remarkable flexibility can be attributed to 3 key elements: the long-pulse time structure and low repetition rate of the ESS neutron source, the chopper cascade that tailors the moderator pulse in the primary part of the spectrometer, and the bent Si(111) analyzer crystals arranged in a near-backscattering geometry in the secondary part of the spectrometer. Analytical calculations combined with instrument Monte-Carlo simulations show that the instrument will provide a variable elastic energy resolution, δ(h ω), between 2 and 32 µeV, when using a wavelength of λ ≈ 6.267 Å (Si(111)-reflection), with an energy transfer range, h ω, centered at the elastic line from -600 to +600 µeV. In addition, when selecting λ ≈ 2.08 Å (i.e., the Si(333)-reflection), δ(h ω) can be relaxed to 300 µeV and h ω from about 10 meV in energy gain to ca -40 meV in energy loss. Finally, the dynamic wavelength range of MIRACLES, approximately 1.8 Å, can be shifted within the interval of 2-20 Å to allow the measurement of low-energy inelastic excitations.

[The Value of Ultrasonography Compared with Magnetic Resonance Imaging in the Diagnosis of Deltoid Ligament Injuries--Is there a Difference?]. / Vergleich der Sonografie und der Magnetresonanztomografie zur Diagnostik von Rupturen des Lig. deltoideum--gibt es einen Unterschied?

BACKGROUND: Ruptures of the deltoid ligament can lead to ankle instability which may cause arthrosis. Aim of this comparative clinical trial was to assess the value of ultrasonography (US) compared to magnetic resonance imaging (MRI) in the diagnosis of medial collateral (deltoid) ligament ruptures associated with Weber type B and C fractures. PATIENTS AND METHODS: All four components of the deltoid ligament of the ankles of 28 patients with Weber type B and 14 patients with Weber type C fractures were preoperatively evaluated by US and MRI for partial or complete ruptures. RESULTS: Deltoid ligament injuries were detected in 10 of 28 patients (35.7 %) with Weber type B and in 12 of 14 patients (85.7 %) with Weber type C fractures with MRI. US reliably identified all 17 patients with complete rupture of the deltoid ligament (sensitivity 100 %, specifity 92 %). However only half of the 6 patients who sustained a partial rupture were correctly identified (sensitivity 50 %, specifity 97.2 %). 26 of 30 ruptures (sensitivity 86.6 %, specifity 96.3 %) and 13 of 27 partial ruptures (sensitivity 48.1 %, specifity 97.8 %) of the four components of the deltoid ligament were correctly identified with US. CONCLUSION: US is a reliable procedure for detection of clinically relevant ruptures and uninjured components of the deltoid ligament after distal fibula fractures. However US is not suitable to reliably identify partial ruptures. The treatment decision for operation or conservative treatment of ankle fractures is based on the stability of the ankle. Patients with lateral malleolar fractures and intact medial malleolus but rupture of the deltoid ligament often show a spontaneous reduction of the talus in X-ray images and may therefore be falsely classified as stable (unrecognised medial instability). However, unstable malleolar fractures should be treated with open reduction and internal fixation in order to improve outcome. Hence US is able to influence therapeutic decisions by detecting medial ankle instability, which cannot be detected clinically or radiologically.

Magnetic-field-induced ferroelectric polarization reversal in the multiferroic Ge(1-x)Mn(x)Te semiconductor.

Ge(1-x)Mn(x)Te is shown to be a multiferroic semiconductor, exhibiting both ferromagnetic and ferroelectric properties. By ferromagnetic resonance we demonstrate that both types of order are coupled to each other. As a result, magnetic-field-induced ferroelectric polarization reversal is achieved. Switching of the spontaneous electric dipole moment is monitored by changes in the magnetocrystalline anisotropy. This also reveals that the ferroelectric polarization reversal is accompanied by a reorientation of the hard and easy magnetization axes. By tuning the GeMnTe composition, the interplay between ferromagnetism and ferroelectricity can be controlled.

Molecular beam epitaxy of single phase GeMnTe with high ferromagnetic transition temperature.

Ferromagnetic Ge(1-x)Mn(x)Te is a promising candidate for diluted magnetic semiconductors because solid solutions exist over a wide range of compositions up to x(Mn)≈0.5, where a maximum in the total magnetization occurs. In this work, a systematic study of molecular beam epitaxy of GeMnTe on (1 1 1) BaF(2) substrates is presented, in which the Mn concentration as well as growth conditions were varied over a wide range. The results demonstrate that single phase growth of GeMnTe can be achieved only in a narrow window of growth conditions, whereas at low as well as high temperatures secondary phases or even phase separation occurs. The formation of secondary phases strongly reduces the layer magnetization as well as the Curie temperatures. Under optimized conditions, single phase GeMnTe layers are obtained with Curie temperatures as high as 200 K for Mn concentrations close to the solubility limit of x(Mn)=50%.

Trapped-ion antennae for the transmission of quantum information.

More than 100 years ago, Hertz succeeded in transmitting signals over a few metres to a receiving antenna using an electromagnetic oscillator, thus proving the electromagnetic theory developed by Maxwell. Since this seminal work, technology has developed, and various oscillators are now available at the quantum mechanical level. For quantized electromagnetic oscillations, atoms in cavities can be used to couple electric fields. However, a quantum mechanical link between two mechanical oscillators (such as cantilevers or the vibrational modes of trapped atoms or ions) has been rarely demonstrated and has been achieved only indirectly. Examples include the mechanical transport of atoms carrying quantum information or the use of spontaneously emitted photons. Here we achieve direct coupling between the motional dipoles of separately trapped ions over a distance of 54 micrometres, using the dipole-dipole interaction as a quantum mechanical transmission line. This interaction is small between single trapped ions, but the coupling is amplified by using additional trapped ions as antennae. With three ions in each well, the interaction is increased by a factor of seven compared to the single-ion case. This enhancement facilitates bridging of larger distances and relaxes the constraints on the miniaturization of trap electrodes. The system provides a building block for quantum computers and opportunities for coupling different types of quantum systems.

Severe kyphoscoliosis after primary Echinococcus granulosus infection of the spine.

A primary Echinococcus granulosus infection of the spine involving the vertebrae T8 and T9 of a 6-year-old child was treated elsewhere by thoracotomy, partial corporectomy, multiple laminectomies and uninstrumented fusion. Owing to inappropriate stabilization, severe deformity developed secondary to these surgeries. X-rays, CT and MRI scans of the spine revealed a severe thoracic kyphoscoliosis of more than 100 degrees (Fig. 1) and recurrence of Echinococcus granulosus infection. The intraspinal cyst formation was located between the stretched dural sac and the vertebral bodies of the kyphotic apex causing significant compression of the cord (Figs. 2, 3, 4). A progressive neurologic deficit was reported by the patient. At the time of referral, the patient was wheelchair bound and unable to walk by herself (Frankel Grade C). Standard antiinfectious therapy of Echinococcus granulosus requires a minimum treatment period of 3 months. This should be done before any surgical intervention because in case of a rupture of an active cyst, the delivered lipoprotein antigens of the parasite may cause a potentially lethal anaphylactic shock. Owing to the critical neurological status, we decided to perform surgery without full length preoperative antiinfectious therapy. Surgical treatment consisted in posterior vertebral column resection technique with an extensive bilateral costotransversectomy over three levels, re-decompression with cyst excision around the apex and multilevel corporectomy of the apex of the deformity. Stabilisation and correction of the spinal deformity were done by insertion of a vertebral body replacement cage anteriorly and posterior shortening by compression and by a multisegmental pedicle screw construct. After the surgery, antihelminthic therapy was continued. The patients neurological deficits resolved quickly: 4 weeks after surgery, the patient had Frankel Grade D and was ambulatory without any assistance. After an 18-month follow-up, the patient is free of recurrence of infection and free of neurologically deficits (Frankel E). This case demonstrates that inappropriate treatment--partial resection of the cyst, inappropriate anterior stabilization and posterior multilevel laminectomies without posterior stabilization--may lead to severe progressive kyphoscoliotic deformity and recurrence of infection, both leading to significant neurological injury presenting as a very difficult to treat pathology. Fig. 1 X-rays of the patient showing a kyhoscoliotic deformity. a ap view, b lateral view Fig. 2 CT reconstruction of the whole spine showing the apex of the deformity is located in the area of the previous surgeries Fig. 3 Sagittal CT-cut showing the bone bloc at the apex with a translation deformity Fig. 4 Sagittal T2-weighted MRI image showing the cystic formation at the apex.

[Patterns and causes of injuries in a contemporary combat environment]. / Verletzungsmuster und -ursachen in modernen Kriegen.

Epidemiological analyses of injury patterns and mechanisms help to identify the expertise military surgeons need in a combat setting and accordingly help to adjust infrastructure and training requirements. Therefore, a MEDLINE search (1949-2009), World Wide Web search (keywords "combat, casualties, war, military, wounded and neurosurgery") and an analysis of deaths among allied war casualties in Afghanistan and Iraq were performed. Up to 10th December 2009 there had been 4,688 allied military deaths in Iraq and 1,538 in Afghanistan. Of these 22% died in non-hostile action, 33% in direct combat situations and the majority of 45% in indirect combat actions. The leading causes of injury were explosive devices (70%) and gunshot wounds. Chest or abdominal injuries (40%) and traumatic brain injuries (35%) were the main causes of death for soldiers killed in action. The case fatality rate in Iraq is approximately half that of the Vietnam War, whereas the killed-in-action rate in Afghanistan (18.7%) is similar to the Vietnam War (20%); however, the amputation rate is twice as high in modern conflicts. Approximately 8-15% of the fatal injuries seem to be potentially survivable.Military surgeons must have an excellent expertise in a wide variety of surgical specialties. Life saving emergency care, especially in the fields of thoracic, visceral and vascular surgery as well as practical skills in the fields of neurosurgery and oral and maxillofacial surgery are required. Additionally, it is of vital importance to ensure the availability of sufficient tactical and strategic medical evacuation capabilities for the wounded.

Controlled aggregation of magnetic ions in a semiconductor: an experimental demonstration.

The control on the distribution of magnetic ions into a semiconducting host is crucial for the functionality of magnetically doped semiconductors. Through a structural analysis at the nanoscale, we give experimental evidence that the aggregation of Fe ions in (Ga,Fe)N and consequently the magnetic response of the material are affected by the growth rate and doping with shallow impurities.

Electronic transport in phosphorus-doped silicon nanocrystal networks.

We have investigated the role of doping and paramagnetic states on the electronic transport of networks assembled from freestanding Si nanocrystals (Si-NCs). Electrically detected magnetic resonance (EDMR) studies on Si-NCs films, which show a strong increase of conductivity with doping of individual Si-NCs, reveal that P donors and Si dangling bonds contribute to dark conductivity via spin-dependent hopping, whereas in photoconductivity, these states act as spin-dependent recombination centers of photogenerated electrons and holes. Comparison between EDMR and conventional electron paramagnetic resonance shows that different subsets of P-doped nanocrystals contribute to the different transport processes.

New sources and instrumentation for neutrons in biology.

Neutron radiation offers significant advantages for the study of biological molecular structure and dynamics. A broad and significant effort towards instrumental and methodological development to facilitate biology experiments at neutron sources worldwide is reviewed.

Strain induced changes in the magnetic phase diagram of metamagnetic heteroepitaxial EuSe/PbSe(1-x)Tex multilayers.

Multilayers of strained metamagnetic EuSe intercalated with nonmagnetic PbSe1-xTex were grown by molecular beam epitaxy under conditions optimized by electron diffraction. From detailed structural and magnetic characterization using anomalous synchrotron x-ray diffraction and magnetization measurements, the phase transition temperatures and the magnetic phase diagrams of strained EuSe as a function of the in-plane lattice constant are determined. In this way, it is demonstrated that the magnetic properties of the samples can be significantly changed by applying biaxial strain on EuSe in superlattice structures.

Direct determination of strain and composition profiles in SiGe islands by anomalous x-Ray diffraction at high momentum transfer.

Anomalous x-ray scattering is employed for quantitative measurements of the Ge composition profile in islands on Si(001). The anomalous effect in SiGe is enhanced exploiting the dependence of the complex atomic form factors on the momentum transfer. Comparing the intensity ratios for x-ray energies below and close to the K edge of Ge at various Bragg reflections in the grazing incidence diffraction setup, the sensitivity for the Ge profile is considerably enhanced. The method is demonstrated for SiGe dome-shaped islands grown on Si(001). It is found that the composition inside the island changes rather abruptly, whereas the lattice parameter relaxes continuously.

Experimental evidence for fast heterogeneous collective structural relaxation in a supercooled liquid near the glass transition

We have extended the exploration of microscopic dynamics of supercooled liquids to small wave numbers Q corresponding to the scale of intermediate range order, by developing a new experimental approach for precise data correction for multiple scattering noise in inelastic coherent neutron scattering. Our results in supercooled Ca0.4K0.6(NO3)(1.4) reveal the first direct experimental evidence, after a decade of controversy, that the so-called picosecond process around the glass transition corresponds to a predicted first, faster stage of the structural relaxation. In addition, they show that this process takes the spatial form of fast heterogeneous collective flow of correlated groups of atoms.

Single-particle dynamics of water molecules confined in a lecithin-based gel.

We present experimental measurements, obtained by a quasielastic neutron scattering experiment, of the self-diffusion coefficient of water confined in the dense structure of lecithin-based gels. The inelastic neutron scattering (INS) technique was also used to monitor the dynamic state of water molecules involved in the gel structure. It is shown that, at least in highly concentrated systems, the diffusional properties of water can be related with the growth process of worm-like aggregates. However, an interpretation of our data consistent with a number of experimental results in the literature and with INS indications requires the adoption of a model in which the gel structure is better described in terms of percolating aggregates rather than the usually described polymer-like entangled (not interconnected) network. In such a way, we are pointing out the existence of an interpretative controversy calling for further investigation to be disentangled. The source of the inconsistencies is found in the commonly accepted basic assumption of the existence of a simple scaling law, relating the average micellar length to the concentration.

Molecular motions and hydration of purple membranes and disk membranes studied by neutron scattering.

Fast stochastic equilibrium fluctuations (time scale: 10(-10)-10(-13) seconds) in purple membranes (MP) and in disk membranes (DM) have been measured with quasielastic incoherent neutron scattering. The comparison of predominantly stochastic motions occurring in purple membranes and in disk membranes revealed qualitatively similar dynamical behaviour. Models of internal motions within restricted volumes have been shown to be useful to fit the spectra from both samples. From fits using these models we found "amplitudes" 15 to 20% larger for motions in DM samples compared to PM samples. This indicates a higher internal flexibility of the DM. Because the dynamical behaviour is very sensitive to the hydration of the protein-lipid complex, we also performed neutron diffraction experiments to determine lamellar spacings as a measure of level of hydration and as a function of temperature. From these studies the interaction of solvent molecules with the surface of the protein-lipid complex appears to be qualitatively similar for both types of membranes.

Function and picosecond dynamics of bacteriorhodopsin in purple membrane at different lipidation and hydration.

By neutron scattering experiments and time-resolved absorption spectroscopy we have investigated picosecond equilibrium fluctuations and the kinetics of the photocycle of bacteriorhodopsin (BR) in the purple membrane (PM). Natural PM samples composed of 75% BR (w/w) and 25% lipid (w/w) as well as delipidated PM having only 5% lipid (w/w) were measured at different levels of hydration. We observed a reduced 'flexibility', due to a diminished weight of stochastic large-amplitude motions occurring in the delipidated PM as compared to the natural PM. This effect is more pronounced for wet samples, indicating the importance of lipid hydration for protein dynamics. The reduced flexibility is accompanied by significantly larger time constants describing the decay of the M-intermediate. Therefore, a correlation between the dynamical behavior of the protein-lipid complex and BR function emerges.

Dehydration of biological membranes by cooling: an investigation on the purple membrane.

The lamellar spacing dl of purple membrane (PM) multilayer systems was investigated with neutron diffraction as a function of temperature and of the level of hydration. The observed large T-dependent variations of dl indicate that PM is partially dehydrated when cooled below a "hydration water freezing point". This phenomenon is reversible, but a hysteresis is observed when PM is rehydrated upon reheating. The hydration water remaining bound to the membrane below about 240 K is non-freezing. Its amount was found to be hnf=0.24(+/-0.02) g 2H2O/g BR for all samples equilibrated at room temperature in the presence of 2H2O vapour at >/=84% r.h. It is evident, that the dehydration/rehydration behaviour of PM is strongly correlated with the temperature-dependent behaviour of the dynamical structure factor. Above the well-known "dynamical transition" announcing the onset of localized diffusive molecular motions between 190 K and 230 K, a second dynamical transition is caused by the temperature-induced rehydration of the PM starting near 255 K. This is also correlated with the deviation from a pure Arrhenius law of the rate-limiting process in the photocycle, known to occur upon cooling beyond the ice point into the same temperature region. Our results suggest that the phenomenon of dehydration and rehydration induced by cooling and reheating, respectively, is a general property of biological membranes.