Improving Atmospheric Angular Momentum Forecasts by Machine Learning

Earth angular momentum forecasts are naturally accompanied by forecast errors that typically grow with increasing forecast length. In contrast to this behavior, we have detected large quasi-periodic deviations between atmospheric angular momentum wind term forecasts and their subsequently available analysis. The respective errors are not random and have some hard to define yet clearly visible characteristics which may help to separate them from the true forecast information. These kinds of problems, which should be automated but involve some adaptation and decision-making in the process, are most suitable for machine learning methods. Consequently, we propose and apply a neural network to the task of removing the detected artificial forecast errors. We found that a cascading forward neural network model performed best in this problem. A total error reduction with respect to the unaltered forecasts amounts to about 30% integrated over a 6-days forecast period. Integrated over the initial 3-days forecast period, in which the largest artificial errors are present, the improvements amount to about 50%. After the application of the neural network, the remaining error distribution shows the expected growth with forecast length. However, a 24-hourly modulation and an initial baseline error of 2 × 10−8 became evident that were hidden before under the larger forecast error

Purification, characterisation and crystallisation of photosystem II from Thermosynechococcus elongatus cultivated in a new type of photobioreactor

AbstractThe thermophilic cyanobacterium Thermosynechococcus elongatus was cultivated under controlled growth conditions using a new type of photobioreactor, allowing us to optimise growth conditions and the biomass yield. A fast large-scale purification method for monomeric and dimeric photosystem II (PSII) solubilized from thylakoid membranes of this cyanobacterium was developed using fast protein liquid chromatography (FPLC). The obtained PSII core complexes (PSIIcc) were analysed for their pigment stoichiometry, photochemical and oxygen evolution activities, as well as lipid and detergent composition. Thirty-six chlorophyll a (Chla), 2 pheophytin a (Pheoa), 9± 1 β-carotene (Car), 2.9±0.8 plastoquinone 9 (PQ9) and 3.8±0.5 Mn were found per active centre. For the monomeric and dimeric PSIIcc, 18 and 20 lipid as well as 145 and 220 detergent molecules were found in the detergent shell, respectively. The monomeric and dimeric complexes showed high oxygen evolution activity with 1/4 O2 released per 37–38 Chla and flash in the best cases. Crystals were obtained from dimeric PSIIcc by a micro-batch method. They diffract synchrotron X-rays to a maximum resolution of 2.9-Å, resulting in complete data sets of 3.2 Å resolution

Spectroscopic twin to the hypervelocity sdO star US 708 and three fast sdB stars from the Hyper-MUCHFUSS project

Important tracers for the dark matter halo of the Galaxy are hypervelocity stars (HVSs), which are faster than the local escape velocity of the Galaxy and their slower counterparts, the high-velocity stars in the Galactic halo. Such HVSs are believed to be ejected from the Galactic centre (GC) through tidal disruption of a binary by the super-massive black hole (Hills mechanism). The Hyper-MUCHFUSS survey aims at finding high-velocity potentially unbound hot subdwarf stars. We present the spectroscopic and kinematical analyses of a He-sdO as well as three candidates among the sdB stars using optical Keck/ESI and VLT (X-shooter, FORS) spectroscopy. Proper motions are determined by combining positions from early-epoch photographic plates with those derived from modern digital sky surveys. The Galactic rest frame velocities range from 203 km s^(-1) to 660 km s^(-1), indicating that most likely all four stars are gravitationally bound to the Galaxy. With T_(eff) = 47 000 K and a surface gravity of log g = 5.7, SDSS J205030.39−061957.8 (J2050) is a spectroscopic twin of the hypervelocity He-sdO US 708. As for the latter, the GC is excluded as a place of origin based on the kinematic analysis. Hence, the Hills mechanism can be excluded for J2050. The ejection velocity is much more moderate (385 ± 79 km s^(-1)) than that of US 708 (998 ± 68 km s^(-1)). The binary thermonuclear supernova scenario suggested for US 708 would explain the observed properties of J2050 very well without pushing the model parameters to their extreme limits, as required for US 708. Accordingly, the star would be the surviving donor of a type Ia supernova. Three sdB stars also showed extreme kinematics; one could be a HVS ejected from the GC, whereas the other two could be ejected from the Galactic disk through the binary supernova mechanism. Alternatively, they might be extreme halo stars

Estimating ocean tide model uncertainties for electromagnetic inversion studies

Over a decade ago the semidiurnal lunar M2 ocean tide was identified in CHAMP satellite magnetometer data. Since then and especially since the launch of the satellite mission Swarm, electromagnetic tidal observations from satellites are increasingly used to infer electric properties of the upper mantle. In most of these inversions, ocean tidal models are used to generate oceanic tidal electromagnetic signals via electromagnetic induction. The modeled signals are subsequently compared to the satellite observations. During the inversion, since the tidal models are considered error free, discrepancies between forward models and observations are projected only onto the induction part of the modeling, e.g., Earth's conductivity distribution. Our study analyzes uncertainties in oceanic tidal models from an electromagnetic point of view. Velocities from hydrodynamic and assimilative tidal models are converted into tidal electromagnetic signals and compared. Respective uncertainties are estimated. The studies main goal is to provide errors for electromagnetic inversion studies. At satellite height, the differences between the hydrodynamic tidal models are found to reach up to 2&thinsp;nT, i.e., over 100&thinsp;% of the local M2 signal. Assimilative tidal models show smaller differences of up to 0.1&thinsp;nT, which in some locations still corresponds to over 30&thinsp;% of the M2 signal.</p

Erratum to: The pivot shift: a global user guide

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Reliability of measures of impairments associated with patellofemoral pain syndrome

BACKGROUND: The reliability and measurement error of several impairment measures used during the clinical examination of patients with patellofemoral pain syndrome (PFPS) has not been established. The purpose was to determine the inter-tester reliability and measurement error of measures of impairments associated with PFPS in patients with PFPS. METHODS: A single group repeated measures design was used. Two pairs of physical therapists participated in data collection. Examiners were blinded to each others' measurements. RESULTS: Thirty patients (age 29 +/- 8; 17 female) with PFPS participated in this study. Inter-tester reliability coefficients were substantial for measures of hamstrings, quadriceps, plantarflexors, and ITB/TFL complex length, hip abductors strength, and foot pronation (ICCs from .85 to .97); moderate for measures of Q-angle, tibial torsion, hip external rotation strength, lateral retinacular tightness, and quality of movement during a step down task (ICCs from .67 to .79); and poor for femoral anteversion (ICC of .45). Standard error of measurement (SEM) for measures of muscle length ranged from 1.6 degrees to 4.3 degrees. SEM for Q-angle, tibial torsion, and femoral anteversion were 2.4 degrees, 2.9 degrees, and 4.5 degrees respectively. SEM for foot pronation was 1 mm. SEM for measures of muscle strength was 1.8 Kg for abduction and 2.4 Kg for external rotation. CONCLUSION: Several of the impairments associated with PFPS had sufficient reliability and low measurement error. Further investigation is needed to test if these impairment measurements are related to physical function and whether or not they are useful for decision-making

Co-occurrence of the bla(VIM-1) and bla(SHV-12) genes on an IncHI2 plasmid of an Escherichia coli isolate recovered from German livestock

The dissemination of carbapenemase-producing Enterobacterales (CPE) is an important public health issue. The number of human CPE isolates has been steadily increasing during recent years, worldwide. Despite the fact that carbapenems are not licensed for use in veterinary medicine, increasing numbers of CPE from the veterinary sector have been reported. The transmission of CPE between pets/livestock and exposed humans as well as via food has been demonstrated. In this study, a detailed characterization of a carbapenem-resistant porcine Escherichia coli co-harbouring blaVIM-1, blaSHV-12 and blaACC-1 genes, along with other resistance genes, is provided

Electromagnetic characteristics of ENSO

The motion of electrically conducting sea water through Earth's magnetic field induces secondary electromagnetic fields. Due to its periodicity, the oceanic tidally induced magnetic field is easily distinguishable in magnetic field measurements and therefore detectable. These tidally induced signatures in the electromagnetic fields are also sensitive to changes in oceanic temperature and salinity distributions. We investigate the impact of oceanic heat and salinity changes related to the El Niño–Southern Oscillation (ENSO) on oceanic tidally induced magnetic fields. Synthetic hydrographic data containing characteristic ENSO dynamics have been derived from a coupled ocean–atmosphere simulation covering a period of 50 years. The corresponding tidally induced magnetic signals have been calculated with the 3-D induction solver x3dg. By means of the Oceanic Niño Index (ONI), based on sea surface temperature anomalies, and a corresponding Magnetic Niño Index (MaNI), based on anomalies in the oceanic tidally induced magnetic field at sea level, we demonstrate that evidence of developing ENSO events can be found in the oceanic magnetic fields statistically 4 months earlier than in sea surface temperatures. The analysis of the spatio-temporal progression of the oceanic magnetic field anomalies offers a deeper understanding on the underlying oceanic processes and is used to test and validate the initial findings

Impure Aspects of Supersymmetric Wilson Loops

We study a general class of supersymmetric Wilson loops operator in N = 4 super Yang-Mills theory, obtained as orbits of conformal transformations. These loops are the natural generalization of the familiar circular Wilson-Maldacena operator and their supersymmetric properties are encoded into a Killing spinor that is not pure. We present a systematic analysis of their scalar couplings and of the preserved supercharges, modulo the action of the global symmetry group, both in the compact and in the non-compact case. The quantum behavior of their expectation value is also addressed, in the simplest case of the Lissajous contours: explicit computations at weak-coupling, through Feynman diagrams expansion, and at strong-coupling, by means of AdS/CFT correspondence, suggest the possibility of an exact evaluation.Comment: 40 pages, 4 figure