499 research outputs found
Universality of Hofstadter butterflies on hyperbolic lattices
Motivated by recent experimental breakthroughs in realizing hyperbolic
lattices in superconducting waveguides and electric circuits, we compute the
Hofstadter butterfly on regular hyperbolic tilings. By utilizing large
hyperbolic lattices with periodic boundary conditions, we obtain the true
hyperbolic bulk spectrum that is unaffected by contributions from boundary
states. Our results reveal that the butterfly spectrum with large extended
gapped regions prevails and that its shape is universally determined by the
number of edges of the fundamental tile, while the fractal structure is lost in
such a non-Euclidean case. We explain how these intriguing features are related
to the nature of Landau levels in hyperbolic space, and how they could be
verified experimentally.Comment: 4 pages, 3 figures + supplementar
A population-based case-control study on social factors and risk of testicular germ cell tumours
Objectives Incidence rates for testicular cancer have risen over the last few decades. Findings of an association between the risk of testicular cancer and social factors are controversial. The association of testicular cancer and different indicators of social factors were examined in this study.<p></p>
Design Case–control study.<p></p>
Setting Population-based multicentre study in four German regions (city states Bremen and Hamburg, the Saarland region and the city of Essen).<p></p>
Participants The study included 797 control participants and 266 participants newly diagnosed with testicular cancer of which 167 cases were classified as seminoma and 99 as non-seminoma. The age of study participants ranged from 15 to 69 years.<p></p>
Methods Social position was classified by educational attainment level, posteducational training, occupational sectors according to Erikson-Goldthorpe-Portocarrero (EGP) and the socioeconomic status (SES) on the basis of the International SocioEconomic Index of occupational status (ISEI). ORs and corresponding 95% CIs (95% CIs) were calculated for the whole study sample and for seminoma and non-seminoma separately.<p></p>
Results Testicular cancer risk was modestly increased among participants with an apprenticeship (OR=1.7 (95% CI 1.0 to 2.8)) or a university degree (OR=1.6 (95% CI 0.9 to 2.8)) relative to those whose education was limited to school. Analysis of occupational sectors revealed an excess risk for farmers and farm-related occupations. No clear trend was observed for the analyses according to the ISEI-scale.<p></p>
Conclusions Social factors based on occupational measures were not a risk factor for testicular cancer in this study. The elevated risk in farmers and farm-related occupations warrants further research including analysis of occupational exposures.<p></p>
Charge carrier injection into insulating media: single-particle versus mean-field approach
Self-consistent, mean-field description of charge injection into a dielectric
medium is modified to account for discreteness of charge carriers. The improved
scheme includes both the Schottky barrier lowering due to the individual image
charge and the barrier change due to the field penetration into the injecting
electrode that ensures validity of the model at both high and low injection
rates including the barrier dominated and the space-charge dominated regimes.
Comparison of the theory with experiment on an unipolar ITO/PPV/Au-device is
presented.Comment: 32 pages, 9 figures; revised version accepted to PR
Duration and predictors of emergency surgical operations - basis for medical management of mass casualty incidents
<p>Abstract</p> <p>Background</p> <p>Hospitals have a critically important role in the management of mass causality incidents (MCI), yet there is little information to assist emergency planners. A significantly limiting factor of a hospital's capability to treat those affected is its surgical capacity. We therefore intended to provide data about the duration and predictors of life saving operations.</p> <p>Methods</p> <p>The data of 20,815 predominantly blunt trauma patients recorded in the Trauma Registry of the German-Trauma-Society was retrospectively analyzed to calculate the duration of life-saving operations as well as their predictors. Inclusion criteria were an ISS ≥ 16 and the performance of relevant ICPM-coded procedures within 6 h of admission.</p> <p>Results</p> <p>From 1,228 patients fulfilling the inclusion criteria 1,793 operations could be identified as life-saving operations. Acute injuries to the abdomen accounted for 54.1% followed by head injuries (26.3%), pelvic injuries (11.5%), thoracic injuries (5.0%) and major amputations (3.1%). The mean cut to suture time was 130 min (IQR 65-165 min). Logistic regression revealed 8 variables associated with an emergency operation: AIS of abdomen ≥ 3 (OR 4,00), ISS ≥ 35 (OR 2,94), hemoglobin level ≤ 8 mg/dL (OR 1,40), pulse rate on hospital admission < 40 or > 120/min (OR 1,39), blood pressure on hospital admission < 90 mmHg (OR 1,35), prehospital infusion volume ≥ 2000 ml (OR 1,34), GCS ≤ 8 (OR 1,32) and anisocoria (OR 1,28) on-scene.</p> <p>Conclusions</p> <p>The mean operation time of 130 min calculated for emergency life-saving surgical operations provides a realistic guideline for the prospective treatment capacity which can be estimated and projected into an actual incident admission capacity. Knowledge of predictive factors for life-saving emergency operations helps to identify those patients that need most urgent operative treatment in case of blunt MCI.</p
Mitochondrial fusion is a therapeutic vulnerability of acute myeloid leukemia
Mitochondrial metabolism recently emerged as a critical dependency in acute myeloid leukemia (AML). The shape of mitochondria is tightly regulated by dynamin GTPase proteins, which drive opposing fusion and fission forces to consistently adapt bioenergetics to the cellular context. Here, we showed that targeting mitochondrial fusion was a new vulnerability of AML cells, when assayed in patient-derived xenograft (PDX) models. Genetic depletion of mitofusin 2 (MFN2) or optic atrophy 1 (OPA1) or pharmacological inhibition of OPA1 (MYLS22) blocked mitochondrial fusion and had significant anti-leukemic activity, while having limited impact on normal hematopoietic cells ex vivo and in vivo. Mechanistically, inhibition of mitochondrial fusion disrupted mitochondrial respiration and reactive oxygen species production, leading to cell cycle arrest at the G/G transition. These results nominate the inhibition of mitochondrial fusion as a promising therapeutic approach for AML
Genetic and Proteomic Approaches to Identify Cancer Drug Targets
While target-based small-molecule discovery has taken centre-stage in the pharmaceutical industry, there are many cancer-promoting proteins not easily addressed with a traditional target-based screening approach. In order to address this problem, as well as to identify modulators of biological states in the absence of knowing the protein target of the state switch, alternative phenotypic screening approaches, such as gene expression-based and high-content imaging, have been developed. With this renewed interest in phenotypic screening, however, comes the challenge of identifying the binding protein target(s) of small-molecule hits. Emerging technologies have the potential to improve the process of target identification. In this review, we discuss the application of genomic (gene expression-based), genetic (short hairpin RNA and open reading frame screening), and proteomic approaches to protein target identification
Realizing efficient topological temporal pumping in electrical circuits
Quantized adiabatic transport can occur when a system is slowly modulated
over time. In most realizations however, the efficiency of such transport is
reduced by unwanted dissipation, back-scattering, and non-adiabatic effects. In
this work, we realize a topological adiabatic pump in an electrical circuit
network that supports remarkably stable and long-lasting pumping of a voltage
signal. We further characterize the topology of our system by deducing the
Chern number from the measured edge band structure. To achieve this, the
experimental setup makes use of active circuit elements that act as
time-variable voltage-controlled inductors.Comment: main (5 pages, 3 figures) plus supplement (8 pages, 4 figures
First results of the bundle test QUENCH-19 with FeCrAl claddings
The QUENCH-19 bundle experiment with FeCrAl(Y) claddings and 4 FeCrAl(Y) spacer grids as well as 8 KANTHAL APM corner rods and KANTHAL APM shroud was conducted at KIT on 29th August 2018. This was performed in cooperation with the Oakridge National Laboratory (ORNL).
The test objective was the comparison of FeCrAl(Y) and ZIRLO™ claddings under similar electrical power and gas flow conditions. In common with the previous QUENCH-15 experiment, the bundle was heated by a series of stepwise increases of electrical power from room temperature to a maximum of ≈600 °C in an atmosphere of flowing argon (3.45 g/s) and superheated steam (3.6 g/s). The bundle was stabilised at this temperature, the electrical power being ≈4 kW. During this time the operation of the various systems was checked.
In a first transient, the electrical power was controlled with the same electrical power history as the QUENCH-15 test. As a result, the bundle was heated to peak cladding temperature of about 1000 °C reached at about 4000 s. It showed a slowed bundle heating than for the QUENCH-15 bundle (1200 °C reached at about 3000 s). In this test phase about 0.3 g of hydrogen were produced (QUENCH-15: 23.3 g).
In the following phase, the power was increased continuously to 18.12 kW (corresponds to maximal power of the QUENCH-15 test). After reaching of this value the power was kept constant during about 2000 s. At the end of this phase the maximal peak cladding temperature of Tpct≈1500 °C was reached. Much lower heating rate in comparison to QUENCH-15 was measured. Exceeding Tpct≈1400 °C sharp increase of hydrogen release rate was observed.
Then reflood was initiated at ≈9100 s, connected with switching the argon injection to the top of the bundle, first rapidly filling the lower plenum of the test section with 4 kg of water, and continuing by injecting ≈48 g/s of water. The electrical power was reduced to 4.1 kW during the reflood.
A temperature excursion was not observed. The temperatures at all elevations decrease immediately after water injection. The total hydrogen release during the whole test was 9.2 g compared to 47.6 g in the QUENCH-15 test with much shorter high electrical power phase.
The videoscope observation of the bundle at the positions of the withdrawn corner rods showed the damage of several claddings at the bundle elevations between 850 and 1000 mm. The claddings were failed either due to interaction with melted thermocouples (mostly) or by spalling of small annular cladding parts
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