8,929 research outputs found
Advances in Oxygen Isotope Analysis of Phosphate by Electrospray Orbitrap Mass Spectrometry for Studying the Microbial Metabolism of Microorganisms
Understanding the impact of human activities on the metabolic state of soil and aquatic environments is of paramount importance to implement measures for maintaining ecosystem services. Variations of natural abundance 18O/16O ratios in phosphate have been proposed as proxies for the holistic assessment of metabolic activity given the crucial importance of phosphoryl transfer reactions in fundamental biological processes. However, instrumental and procedural limitations inherent to oxygen isotope analysis in phosphate and organophosphorus compounds have so far limited the stable isotope-based evaluation of metabolic processes. Here, we discuss how recent developments in Orbitrap high resolution mass spectrometry enable measurements of 18O/16O ratios in phosphate and outline the critical mass spectrometry parameters for accurate and precise analysis. Subsequently, we evaluate the types of 18O kinetic isotope effects of phosphoryl transfer reactions and illustrate how novel analytical approaches will give rise to an improved understanding of 18O/16O ratio variations from biochemical processes affecting the microbial phosphorus metabolism
Surface water floods in Switzerland: what insurance claim records tell us about the damage in space and time
Surface water floods (SWFs) have received increasing attention in the recent
years. Nevertheless, we still know relatively little about where, when and
why such floods occur and cause damage, largely due to a lack of data but
to some degree also because of terminological ambiguities. Therefore, in a
preparatory step, we summarize related terms and identify the need for
unequivocal terminology across disciplines and international boundaries in
order to bring the science together. Thereafter, we introduce a large
(n = 63 117), long (10–33 years) and representative
(48 % of all Swiss buildings covered) data set of spatially explicit
Swiss insurance flood claims. Based on registered flood damage to buildings,
the main aims of this study are twofold: First, we introduce a method to
differentiate damage caused by SWFs and fluvial floods based on the
geographical location of each damaged object in relation to flood hazard maps
and the hydrological network. Second, we analyze the data with respect to
their spatial and temporal distributions aimed at quantitatively answering
the fundamental questions of how relevant SWF damage really is, as well as
where and when it occurs in space and time.
This study reveals that SWFs are responsible for at least 45 % of the
flood damage to buildings and 23 % of the associated direct tangible
losses, whereas lower losses per claim are responsible for the lower loss
share. The Swiss lowlands are affected more heavily by SWFs than the alpine
regions. At the same time, the results show that the damage claims and
associated losses are not evenly distributed within each region either.
Damage caused by SWFs occurs by far most frequently in summer in almost all
regions. The normalized SWF damage of all regions shows no significant upward
trend between 1993 and 2013. We conclude that SWFs are in fact a highly
relevant process in Switzerland that should receive similar attention like
fluvial flood hazards. Moreover, as SWF damage almost always coincides with
fluvial flood damage, we suggest considering SWFs, like fluvial floods, as integrated processes of
our catchments
In-line filter included into the syringe infusion pump assembly reduces flow irregularities
Purpose: To evaluate whether an in-line filter inserted in the syringe pump infusion line assembly influences start-up times and flow irregularities during vertical pump displacement at low infusion rates. Methods: Fluid delivery after syringe pump start-up and after vertical displacement of the syringe pump by −50cm was determined gravimetrically at flow rates of 0.5, 1.0 and 2.0mlh−1. Measurements were repeated for each flow rate four times with two different syringe pumps with and without an in-line filter incorporated. Data are shown as median and range. Results: Start-up times were reduced by an in-line filter at 0.5mlh−1 flow rate from 355.5s (0-660) to 115s (0-320), whereas the effect was attenuated at higher flow rates. Pooling of fluid into the infusion system after lowering the infusion syringe pump was halved in all flow rates tested. Amount of infusion bolus after elevating the syringe pump by 50cm was not affected by an in-line filter. Conclusion: In the evaluated model in-line filters help to reduce flow irregularities and delay in drug delivery of syringe pumps at low flow rates and represent an option to optimize continuous administration of highly concentrated short-acting drugs at very small infusion rate
Sum Rules and Moments of the Nucleon Spin Structure Functions
The nucleon has been used as a laboratory to investigate its own spin
structure and Quantum Chromodynamics. New experimental data on nucleon spin
structure at low to intermediate momentum transfers combined with existing high
momentum transfer data offer a comprehensive picture of the transition region
from the {\it confinement} regime of the theory to its {\it asymptotic freedom}
regime. Insight for some aspects of the theory is gained by exploring lower
moments of spin structure functions and their corresponding sum rules (i.e. the
Gerasimov-Drell-Hearn, Bjorken and Burkhardt-Cottingham). These moments are
expressed in terms of an operator product expansion using quark and gluon
degrees of freedom at moderately large momentum transfers. The sum rules are
verified to a good accuracy assuming that no singular behavior of the structure
functions is present at very high excitation energies. The higher twist
contributions have been examined through the moments evolution as the moments
evolution as the momentum transfer varies from higher to lower values.
Furthermore, QCD-inspired low-energy effective theories, which explicitly
include chiral symmetry breaking, are tested at low momentum transfers. The
validity of these theories is further examined as the momentum transfer
increases to moderate values. It is found that chiral perturbation calculations
agree reasonably well with the first moment of the spin structure function
at momentum transfer of 0.1 GeV but fail to reproduce the neutron
data in the case of the generalized polarizability .Comment: 21 pages, 4 figures, review for Modern Physics Letters A. Minor
modifications in text and improved quality for one figure. Corrected mistakes
in section
Hypothermia for perinatal asphyxial encephalopathy. A Swiss survey of opinion, practice and cerebral investigations
BACKGROUND: Perinatal asphyxial encephalopathy occurs in 1-per 1000 live births and is associated with high mortality and morbidity. Therapeutic hypothermia increases intact survival and improves neurodevelopmental outcome in survivors.AIMS: To evaluate (i) the opinion and practice of therapeutic hypothermia as a therapy for moderate to severe perinatal asphyxial encephalopathy amongst Swiss neonatologists and paediatric intensive care specialists, (ii) the current clinical management of infants with perinatal asphyxial encephalopathy and (iii) the need for a national perinatal asphyxia and therapeutic hypothermia registry.METHODS: Two web-based questionnaires were sent to 18 senior staff physicians within the Swiss Neonatal Network.RESULTS: Therapeutic hypothermia was considered effective by all responders, however only 11 of 18 units provided therapeutic hypothermia. Cooling was initiated during transfer and performed passively in 82% of centres with a target rectal temperature of 33-34 degrees C. Most units ventilated infants with perinatal asphyxial encephalopathy if clinically indicated and 73% of responders gave analgesia routinely to cooled infants. Neuromonitoring included continuous amplitude integrated EEG (aEEG) and EEG. Neuroimaging included cranial ultrasound (cUS), magnetic resonance imaging (MRI) and computed tomography (CT). Sixty-seven percent of units treating infants with perinatal asphyxial encephalopathy performed MRI routinely. All heads of departments questioned indicated that a "Swiss National Asphyxia and Cooling Registry" is needed.CONCLUSIONS: In Switzerland, access to therapeutic hypothermia is widespread and Swiss neonatologists believe that therapeutic hypothermia for perinatal asphyxia is effective. National cooling protocols are needed for the management of infants with perinatal asphyxial encephalopathy in order to ensure safe cooling, appropriate monitoring, imaging and follow-up assessment. A national registry is needed to collect data on diagnosis, treatment, adverse events and outcome
Selective Harmonic Elimination Model Predictive Control for Multilevel Power Converters
© 2016 IEEE. In this study, a model predictive control (MPC) strategy that combines finite-control-set MPC with selective harmonic elimination (SHE) modulation pattern in its formulation is proposed to govern multilevel power converters. Based on a desired operating point for the system state (converter current reference), an associated predefined SHE voltage pattern is obtained as a required steady-state control input reference. Then, the cost function is formulated with the inclusion of both system state and control input references. According with the proposed reference and cost function formulation, the predictive controller prefers to track the converter output current reference in transients, while preserving the SHE voltage pattern in steady state. Hence, as evidenced by experimental results, a fast dynamic response is obtained throughout transients while a predefined voltage and current spectrum with low switching frequency is achieved in steady state
A novel high dynamic six phase 120 kW Power Hardware in the Loop Emulation Test Bench for emulating AC/DC Grids and Electrical Machines
This paper presents a highly customizable 120kVA Power-Hardware-in-the-Loop test bench. The output stage consist of two identical Parallel Hybrid Converters each with a 17-level output voltage and an effective switching frequency of 1MHz. The Parallel Hybrid Converters can provide 3-phase AC or bipolar DC as output voltage. Thus, one 6-AC, 3-AC or DC system or two systems with 2x3-AC, 1x3-AC and 1xDC or 2xDC can be emulated
A novel high dynamic six phase 120 kW Power Hardware in the Loop Emulation Test Bench for emulating AC/DC Grids and Electrical Machines
This paper presents a highly customizable 120kVA Power-Hardware-in-the-Loop test bench. The output stage consist of two identical Parallel Hybrid Converters each with a 17-level output voltage and an effective switching frequency of 1MHz. The Parallel Hybrid Converters can provide 3-phase AC or bipolar DC as output voltage. Thus, one 6-AC, 3-AC or DC system or two systems with 2x3-AC, 1x3-AC and 1xDC or 2xDC can be emulated
The phase spiral in Gaia DR3
We aim to study the phase spiral in the Milky Way (MW) with Gaia DR3. We used
an edge detection algorithm to find the border of the phase spiral, allowing us
to robustly quantify its shape at different positions and for different
selections. We calculated the time of onset of the phase-mixing by determining
the different turns of the phase spiral and using the vertical frequencies from
commonly used MW potential models. We find that the phase spiral extends down
to kpc in height below the plane (about 3 to 5 scale heights of the thin
disc) and beyond km/s in . We see a secondary branch mostly at
positive vertical velocities when coloured by azimuthal velocity and in the
counts projection. We also find complex variations of the phase spirals with
angular momentum and azimuth. All these possibly provide evidence of multiple
perturbations (from different times or from different perturbers) and/or of the
complexity of the phase mixing process. We detect the phase spiral from 6 to 11
kpc from the Galactic centre and find signatures of vertical asymmetries 1-2
kpc beyond this range. We measure small but clear variations with azimuth. When
we determine the phase mixing times from the phase spiral at different angular
momenta and using the different spiral turns (at different ) we obtain
inconsistent times with systematic differences (times increasing with
and with ). Our determinations are mostly in the range of [0.3-0.9] Gyr,
with an average of 0.5 Gyr. The inconsistencies do not change when using
different usual potential models, different stellar distances or frequencies
for different kinetic temperatures. They could stem from the inconsistency of
potential models with the true MW, and from too simple modelling, in particular
neglecting self-gravity, not considering the multiple perturbations and the
interference with other processes.Comment: accepted for publication in A&
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