Gas-Solid Phase Transition in Laser Multiple Filamentation.

While propagating in transparent media, near-infrared multiterawatt (TW) laser beams break up in a multitude of filaments of typically 100-200 um diameter with peak intensities as high as 10 to 100 TW/cm^{2}. We observe a phase transition at incident beam intensities of 0.4 TW/cm^{2}, where the interaction between filaments induce solidlike two-dimensional crystals with a 2.7 mm lattice constant, independent of the initial beam diameter. Below 0.4 TW/cm^{2}, we evidence a mixed phase state in which some filaments are closely packed in localized clusters, nucleated on inhomogeneities (seeds) in the transverse intensity profile of the beam, and other are sparse with almost no interaction with their neighbors, similar to a gas. This analogy with a thermodynamic gas-solid phase transition is confirmed by calculating the interaction Hamiltonian between neighboring filaments, which takes into account the effect of diffraction, Kerr self-focusing, and plasma generation. The shape of the effective potential is close to a Morse potential with an equilibrium bond length close to the observed value.

Early Liver Transplantation for Severe Alcoholic Hepatitis in the United States--A Single-Center Experience.

Early liver transplantation (LT) in European centers reportedly improved survival in patients with severe alcoholic hepatitis (AH) not responding to medical therapy. Our aim was to determine if a strategy of early LT for severe AH could be applied successfully in the United States. We reviewed 111 patients with severe AH at our center from January 2012 to January 2015. The primary end point was mortality at 6 months or early LT, with a secondary end point of alcohol relapse after LT. Survival was compared between those receiving early LT and matched patients who did not. Using a process similar to the European trial, 94 patients with severe AH not responding to medical therapy were evaluated for early LT. Overall, 9 (9.6%) candidates with favorable psychosocial profiles underwent early LT, comprising 3% of all adult LT during the study period. The 6-month survival rate was higher among those receiving early LT compared with matched controls (89% vs 11%, p<0.001). Eight recipients are alive at a median of 735 days with 1 alcohol relapse. Early LT for severe AH can achieve excellent clinical outcomes with low impact on the donor pool and low rates of alcohol relapse in highly selected patients in the United States.

[Omitted spinal X-ray examination after a fall from a height of 3 m]. / Keine Röntgenuntersuchung der Wirbelsäule nach Sturz aus 3 m Höhe.

A 59-year-old patient with right-sided chest pains after a fall from a height of 3 m was referred to hospital by an emergency physician. The chest x-rays showed fractures of the third and seventh ribs on the right side. Inpatient analgesic therapy was initiated and after 3 days the patient was discharged from hospital for further outpatient treatment. As the pain persisted the patient consulted a surgeon 5 weeks later and the first X-ray examination of the spine was carried out which revealed the formation of several wedge-shaped thoracolumbar vertebral bodies. Further magnetic resonance imaging (MRI) diagnostics also revealed alterations to T10, T12, L1 and L3 as well as radiological signs of Scheuermann's disease; however, a definite statement differentiating these findings from older spinal fractures as a result of the accident was no longer possible. The patient claimed that the hospital failed to perform spinal X-ray investigations leading to prolonged pain and limitations in the quality of life. An external expert stated that the distracting injury of the ribs and the pain medication might have veiled the additional vertebral fractures. Thus, an earlier diagnosis of the apparently stable vertebral fractures would not have changed the conservative therapy approach. The decision of the arbitration board differed from the expert opinion as additional imaging techniques of the spine should have been initially performed due to the mechanism of injury. Although no irreversible damage to health resulted an earlier targeted treatment could have reduced the overall length of therapy.

[Cardiac post-resuscitation care. An indication for trauma whole-body CT?]. / Zustand nach Reanimation. Eine Indikation für die "Traumaspirale"?

We report the case of a 51-year-old male patient who sustained a liver rupture following mechanical cardiopulmonary resuscitation (CPR) with the LUCAS® system. The patient was under anticoagulation and developed an abdominal compartment syndrome. Although the use of mechanical CPR devices, such as the LUCAS® system and the load distributing band (Autopulse®), is becoming more common, there are specific complications described in the literature, which are associated with mechanical CPR. It is important to differentiate between general complications associated with CPR and those which can be attributed to the application of mechanical CPR devices. Using the example of the presented case, this article outlines and discusses these points based on the currently available literature. It should also be noted that mechanical CPR can act in a similar way to chest trauma and can necessitate an investigation with contrast enhanced computed tomography.

Distinct U-shape efficiency-versus-current curves in AlGaN-based deep-ultraviolet light-emitting diodes.

The efficiency of an AlGaN deep-ultraviolet light-emitting diode with peak emission wavelength of 285 nm is investigated as a function of current over a wide range of temperatures (110 K to 300 K). We find that the efficiency-versus-current curve exhibits unique and distinct features over the entire temperature range including three points of inflection. At low temperatures, the change in slope in the efficiency-versus-current curve is particularly pronounced producing a minimum in the efficiency after which the efficiency rises again. Furthermore, at high current density, the low-temperature efficiency exceeds the room-temperature efficiency. The feature-rich efficiency-versus-current curve is consistent with an enhancement in p-type conductivity by field-ionization of acceptors that occurs in the high-injection regime and is particularly pronounced at low temperatures. Differential conductivity measurements show a marked rise in the high-injection regime that is well correlated to the minimum point in the efficiency-versus-current curve.

Septic shock in children in an urban area in Western Germany--outcome, risk factors for mortality and infection epidemiology.

BACKGROUND: Only sparse data exist about children with septic shock in Europe. The present study aimed to evaluate demographics, treatment, outcome and risk factors for mortality in Western Germany. PATIENTS: Children with septic shock aged 2 months to 17 years. METHODS: In a multi-center retrospective study of 20 children's hospitals data were obtained and analyzed by chart review. Risk factors for mortality were identified and assessed by multivariate regression analysis. RESULTS: Overall mortality in 83 cases with septic shock was 25% (21 patients). Significant risk factors were high PRISM III score, low pH, low arterial systolic blood pressure, presence of disseminated intravascular coagulation and extent of multi-organ failure, but not lactate (p=0.05) and base excess (p=0.065). Mortality in hospitals which treated 10 or more patients (category 1) was 17% and increased to 22% in hospitals which treated 3-6 patients (category 2). In hospitals with only 1 or 2 patients (category 3) mortality rate was 61% (p<0.01 when compared to category 1 or 2). A stepwise increase was also seen in the severely sick patients according to PRISM III (>19): category 1: 23%, category 2: 40%, category 3: 62.5% (p<0.05 for comparison of category 1 and 3). Multivariate analysis of significant risk factors revealed low number of treated patients as the only individual risk factor for mortality. CONCLUSION: Mortality from pediatric septic shock in an urban area in Western Germany is high. Disease severity and treatment in a department with few cases were associated with increased mortality.

Enhanced power conversion efficiency of quantum dot sensitized solar cells with near single-crystalline TiO2 nanohelixes used as photoanodes.

Photo-electrodes with tailored three-dimensional nanostructures offer a large enhancement in light harvesting capability for various optoelectronic devices enabled by strong light scattering in the nanostructures as well as improved charge transport. Here we present an array of three-dimensional titanium dioxide (TiO2) nanohelixes fabricated by the oblique angle deposition method as a multifunctional photoanode for CdSe quantum dot sensitized solar cells (QDSSCs). The CdSe QDSSC with a TiO2 nanohelix photoanode shows a 100% higher power conversion efficiency despite less light being absorbed in CdSe QDs when compared with a conventional TiO2 nanoparticle photoanode. We attribute the higher power conversion efficiency to strong light scattering by the TiO2 nanohelixes and much enhanced transport and collection of photo-generated carriers enabled by the unique geometry and near-single crystallinity of the TiO2 nanohelix structure.

Enhanced broadband and omni-directional performance of polycrystalline Si solar cells by using discrete multilayer antireflection coatings.

The performance enhancement of polycrystalline Si solar cells by using an optimized discrete multilayer anti-reflection (AR) coating with broadband and omni-directional characteristics is presented. Discrete multilayer AR coatings are optimized by a genetic algorithm, and experimentally demonstrated by refractive-index tunable SiO2 nano-helix arrays and co-sputtered (SiO2)x(TiO2)1₋x thin film layers. The optimized multilayer AR coating shows a reduced total reflection, leading to the high incident-photon-to-electron conversion efficiency over a correspondingly wide range of wavelengths and incident angles, offering a very promising way to harvest more solar energy by virtually any type of solar cells for a longer time of a day.

Confinement and interaction of single indirect excitons in a voltage-controlled trap formed inside double InGaAs quantum Wells.

Voltage-tunable quantum traps confining individual spatially indirect and long-living excitons are realized by providing a coupled double quantum well with nanoscale gates. This enables us to study the transition from confined multiexcitons down to a single, electrostatically trapped indirect exciton. In the few exciton regime, we observe discrete emission lines identified as resulting from a single dipolar exciton, a biexciton, and a triexciton, respectively. Their energetic splitting is well described by Wigner-like molecular structures reflecting the interplay of dipolar interexcitonic repulsion and spatial quantization.

Ohmic contacts to N-face p-GaN using Ni/Au for the fabrication of polarization inverted light-emitting diodes.

The electrical properties of Ni-based ohmic contacts to N-face p-type GaN were investigated. The specific contact resistance of N-face p-GaN exhibits a linear decrease from 1.01 omega cm2 to 9.05 x 10(-3) omega cm2 for the as-deposited and the annealed Ni/Au contacts, respectively, with increasing annealing temperature. However, the specific contact resistance could be decreased down to 1.03 x 10(-4) omega cm2 by means of surface treatment using an alcohol-based (NH4)2S solution. The depth profile data measured from the intensity of O1s peak in the X-ray photoemission spectra showed that the alcohol-based (NH4)2S treatment was effective in removing the surface oxide layer of GaN.

Experimental and theoretical study of the optical and electrical properties of nanostructured indium tin oxide fabricated by oblique-angle deposition.

Oblique-angle deposition of indium tin oxide (ITO) is used to fabricate optical thin-film coatings with a porous, columnar nanostructure. Indium tin oxide is a material that is widely used in industrial applications because it is both optically transparent and electrically conductive. The ITO coatings are fabricated, using electron-beam evaporation, with a range of deposition angles between 0 degrees (normal incidence) and 80 degrees. As the deposition angle increases, we find that the porosity of the ITO film increases and the refractive index decreases. We measure the resistivity of the ITO film at each deposition angle, and find that as the porosity increases, the resistivity increases superlinearly. A new theoretical model is presented to describe the relationship between the ITO film's resistivity and its porosity. The model takes into account the columnar structure of the film, and agrees very well with the experimental data.

Effects of the refractive index of the encapsulant on the light-extraction efficiency of light-emitting diodes.

We investigate the effects of the refractive index of the encapsulant on the light-extraction efficiency (LEE) of light-emitting diodes (LEDs) for GaN LEDs (n ≈ 2.5) and AlGaInP LEDs (n ≈ 3.0). For non-absorbing rectangular parallelepiped LED chips, as the refractive index of the encapsulant increases, the LEE first increases quasi-linearly, then increases sub-linearly, and finally a saturation is reached. Furthermore, LEDs with a dual-layer graded-refractive-index (GRIN) encapsulant (n(encapsulant 1) = 1.57 and n(encapsulant 2) = 1.41) is fabricated through a two-step curing process. We demonstrate that such an LED further enhances the LEE by reducing Fresnel reflection loss at the encapsulant/air interface by 35% compared with an LED encapsulated with a single-layer encapsulant (n(encapsulant) = 1.57).

Demonstration of optical interference filters utilizing tunable refractive index layers.

Optical interference filters utilizing tunable refractive index layers are shown to have higher spectral fidelity as compared to conventional filters consisting of non-tunable refractive index layers. To demonstrate this increase in spectral fidelity, we design and compare a variety of optical interference filters employing both tunable and non-tunable refractive index layers. Additionally, a five-layer optical interference filter utilizing tunable refractive index layers is designed and fabricated for use with a Xenon lamp to replicate the Air Mass 0 solar irradiance spectrum and is shown to have excellent spectral fidelity.

Dual-functional ultraviolet photodetector with graphene electrodes on AlGaN/GaN heterostructure.

A dual-functional ultraviolet (UV) photodetector with a large UV-to-visible rejection ratio is presented, in which interdigitated finger-type two-dimensional graphene electrodes are introduced to an AlGaN/GaN heterostructure. Two photocurrent generation mechanisms of photovoltaic and photoconductive dominances coexist in the device. The dominance of the mechanisms changes with the induced bias voltage. Below a threshold voltage, the device showed fairly low responsivities but fast response times, as well as a constant photocurrent against the induced bias. However, the opposite characteristics appeared with high bias voltage. Specifically, above the threshold voltage, the device showed high responsivities with additional gain, but slow rise and recovery times. For instance, the responsivity of 10.9 A/W was observed with the gain of 760 at the induced bias voltage of 5 V. This unique multifunctionality enabled by the combination of an AlGaN/GaN heterostructure with graphene electrodes facilitates the development of a single device that can achieve multiple purposes of photodetection.

Improved color rendering and luminous efficacy in phosphor-converted white light-emitting diodes by use of dual-blue emitting active regions.

Conventional white-light sources suffer from a fundamental trade-off between color rendering index and the luminous efficacy; increasing one generally comes at the expense of the other. We demonstrate through simulation that dual-wavelength blue-emitting active regions in phosphor-converted white light sources maximize the output luminous flux while significantly increasing the color rendering ability. Our results indicate that such improvements can be achieved over a broad range of correlated color temperatures.

Unwanted pregnancy as a risk factor for offspring schizophrenia-spectrum and affective disorders in adulthood: a prospective high-risk study.

BACKGROUND: This study investigated whether 'unwanted pregnancy' (i.e. a negative or ambivalent attitude towards the pregnancy/reproduction) is associated with schizophrenia-spectrum and affective disorders in the offspring in adulthood, and if so, whether other pregnancy, perinatal, childhood or genetic-risk factors account for this association. METHOD: In a prospective study beginning during pregnancy, unwanted pregnancy (in combination with other early life risk factors) was studied in relation to adult mental disorders in 75 genetic high-risk (HR) and 91 normal-risk (NR) offspring, defined through maternal psychosis history. Early life risk factors were studied through personal interviews, observations and medical records, and offspring mental disorders were independently diagnosed through follow-up examination at about 22 years of age. RESULTS: Unwanted pregnancy by itself was significantly related to adult offspring schizophrenia-spectrum disorders in both the total sample and the HR subgroup, but the effect was found to be limited to the HR group and occurred in interaction with genetic risk. Other co-temporaneous pregnancy stressors and later perinatal complications, malformations and early childhood environmental stressors could not explain this relationship. Unwanted pregnancy also interacted with genetic-risk status in relating to affective disorders in the offspring. CONCLUSIONS: Unwanted pregnancy, when occurring together with genetic risk for psychosis, was found to be related to both adult schizophrenia-spectrum and affective mental disorders in the offspring. Although the effect of unwanted pregnancy could be mediated by other yet-unidentified factors, unwanted pregnancy might be a functional, discrete environmental psychosocial factor with its own deleterious impact on offspring mental development, when co-occurring with genetic risk.

Laser interferometer measurement of changes in crayfish axon diameter concurrent with action potential.

Small rapid changes in the diameter of an axon takes place when an action potential progresses along the axon. In the giant axon of the crayfish these occur within a period of about 1 millisecond and are typically about 18 angstroms in total amplitude.

Highly efficient light-emitting diodes with microcavities.

One-dimensional microcavities are optical resonators with coplanar reflectors separated by a distance on the order of the optical wavelength. Such structures quantize the energy of photons propagating along the optical axis of the cavity and thereby strongly modify the spontaneous emission properties of a photon-emitting medium inside a microcavity. This report concerns semiconductor light-emitting diodes with the photon-emitting active region of the light-emitting diodes placed inside a microcavity. These devices are shown to have strongly modified emission properties including experimental emission efficiencies that are higher by more than a factor of 5 and theoretical emission efficiencies that are higher by more than a factor of 10 than the emission efficiencies in conventional light-emitting diodes.

Verbal and Cross-Modal Ratings of Music: Validation and Application of an Icon-Based Rating Scale.

Can music be rated consistently using nonverbal descriptors such as colours and temperatures? 144 participants rated 6 experimenter-selected and 2 self-selected pieces of music along 15 bipolar icon (graphic) scales intended to portray emotions, and sensory experiences consisting of colour, temperature, shape, speed, texture, and weight. Participants also rated the same pieces using bipolar verbal scales which aimed to encompass the concepts represented by the icons (e.g., the word "red" for the colour red). Furthermore, the icons themselves were subjected to open-ended verbal labelling to validate the icon scale. Colour icons spontaneously evoked a cross-modal association on 67% of occasions: blue being cool, and red/orange being warm or hot, and the icon scale had overall good face validity. Music regularly and consistently evoked multisensory associations (using the icon scale) including shapes, colours, weight, and temperatures, in addition to emotions. Cross-modal perception is indicative of music's character rather than the enjoyment of the music. The icon scale provides new insights into music perception and for applications where language skill may limit participant expression.