bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of long‐term creep on prestressed concrete beams in relation to deformations and structural resistance: Experiments and modeling
Authors: Reybrouck Nicky , Van Mullem Tim , Taerwe Luc , Caspeele Robby 
Published: March 2020

AbstractRealistic structural models incorporating the time‐dependent effects of concrete are essential in order to make accurate predictions of the time‐dependent deflections at any time of the service life. Experimental databases are used to calibrate and validate existing models for creep and shrinkage available in international standards. However, extensive research campaigns on large‐scale prestressed beams are scarce. In 1967–1985, a research program comprising a unique set of long‐term experimental data on concrete beams was conducted in joint collaboration with four Belgian research institutes to determine the influence of creep and shrinkage on the long‐term behavior of reinforced and prestressed concrete members. The main aim of the final part of the research campaign was the determination of the long‐term behavior of prestressed and partially prestressed beams subjected to permanent loads, considering the influence of the magnitude of the loads, the degree of prestressing, the shape of the cross‐section, the type of prestressing and the stress conditions. This paper reports on the obtained unique set of long‐term tests. Additionally, also information related to the creep and shrinkage data of prisms and the results of the static tests in a four‐point bending configuration until failure at the age of 28 days and 5 years are presented in this paper. The measurements of the prestressed members are compared with a simplified calculation method based on the direct stiffness method, which accounts for aging, creep, and shrinkage. The proposed simplified calculation model allows fast and accurate predictions of strains, stresses, and deflections as a function of time. The results show that the direct stiffness method in combination with the current models of EN1992‐1‐1 and fib Model Code 2010 can predict the long‐term behavior of concrete beams in good agreement with the available experimental data. The research allows to develop more accurate calculation guidelines with respect to the evolution of deflections, concrete deformations and stresses of prestressed beams as function of the prestress‐degree, shape of the cross‐section, and the type of prestressing.
P2Y1‐like nucleotide receptors—Structures, molecular modeling, mutagenesis, and oligomerization
Authors: Neumann Alexander , Müller Christa E. , Namasivayam Vigneshwaran 
Published: March 2020

AbstractThe P2Y receptors (P2YRs) are G protein‐coupled receptors (GPCRs) consisting of eight members, subdivided into two groups, P2Y1‐ and P2Y12‐like receptor subtypes. They are activated by extracellular nucleotides and represent current (P2Y2, P2Y12) or potential future drug targets. The chemical nature of the highly polar endogenous agonists represents a challenge in the discovery and design of potent and bioavailable compounds. A number of mutants and several homology models of P2YR subtypes have been created and updated on the basis of the recently published X‐ray crystal structures of the human P2Y1 and P2Y12Rs. The models were used for prediction of the binding sites of agonists and antagonists, and mutants were constructed for confirmation. Pharmacological data on mutants published for the P2Y1‐like receptors (P2Y1, P2Y2, P2Y4, P2Y6, and P2Y11R) were evaluated to analyze the role of specific amino acids and that of corresponding amino acid residues in related P2Y receptor subtypes. In several P2YR subtypes, an ionic lock between extracellular loop 2 and transmembrane region VII was postulated to be essential for agonist‐induced receptor activation. Mutagenesis and homology modeling data suggest that the nucleotide antagonist (1′R,2′S,4′S,5′S)‐4‐(2‐iodo‐6‐methylaminopurin‐9‐yl)‐1‐[(phosphato)methyl]‐2‐(phosphato)bicyclo[3.1.0]hexane (MRS2500), which was co‐crystallized with the human P2Y1R, binds differently from agonistic nucleotides to a site partly overlapping with that of orthosteric agonists. Hetero‐oligomerization of P2YRs with other P2YR subtypes or other GPCRs may allosterically modulate receptor‐ligand interactions and/or G protein coupling. The collected information will contribute to the understanding of the architecture of P2Y1‐like nucleotide receptors and will consequently be useful for the design of novel agonists and antagonists.This article is categorized under:
Molecular and Statistical Mechanics > Free Energy Methods
Structure and Mechanism > Computational Biochemistry and Biophysics
Molecular and Statistical Mechanics > Molecular Interactions
Software > Molecular Modeling
Observability of the ambient conditions in model‐based estimation for wind farm control: A focus on static models
Authors: Doekemeijer Bart , van Wingerden Jan‐Willem 
Published: March 2020

AbstractWind farm control (WFC) algorithms rely on an estimate of the ambient wind speed, wind direction, and turbulence intensity in the determination of the optimal control setpoints. However, the measurements available in a commercial wind farm do not always carry sufficient information to estimate these atmospheric quantities. In this paper, a novel measure (“observability”) is introduced that quantifies how well the ambient conditions can be estimated with the measurements at hand through a model inversion approach. The usefulness of this measure is shown through several case studies. While the turbine power signals and the inter‐turbine wake interactions provide information on the wind direction, the case studies presented in this article show that there is a strong need for wind direction measurements for WFC to sufficiently cover observability for any ambient condition. Further, generally, more wake interaction leads to a higher observability. Also, the mathematical framework presented in this article supports the straightforward notion that turbine power measurements provide no additional information compared with local wind speed measurements, implying that power measurements are superfluous. Irregular farm layouts result in a higher observability due to the increase in unique wake interaction. The findings in this paper may be used in WFC to predict which ambient quantities can (theoretically) be estimated. The authors envision that this will assist in the estimation of the ambient conditions in WFC algorithms and can lead to an improvement in the performance of WFC algorithms over the complete envelope of wind farm operation.
Symmetries in A-type little string theories. Part II. Eisenstein series and generating functions of multiple divisor sums
Authors: Bastian Brice , Hohenegger Stefan 
Published: March 2020

Abstract
We continue our study of symmetries of a class of little string theories of A-type, which are engineered by N parallel M5-branes probing a flat transverse space. Extending the analysis of the companion paper [1], we discuss the part of the free energy that is sensitive to the details of the 𝔞N−1 gauge structure, by computing explicit series expansions for the cases N = 2, 3, 4. Based on these examples, we find a class of functions that we conjecture to resum whole sectors in the instanton expansion of the free energy and which combine in a natural manner its modular properties as well as the gauge symmetry. These functions have previously been introduced in the literature as the generating functions of multi-divisor sums and in the case N = 2 can also be cast into the form of a generalised Eisenstein series. We use these resummed contributions to the free energy to perform a number of non-trivial consistency checks for our results.
Minimal surfaces and weak gravity
Authors: Demirtas Mehmet , Long Cody , McAllister Liam , Stillman Mike 
Published: March 2020

Abstract
We show that the Weak Gravity Conjecture (WGC) implies a nontrivial upper bound on the volumes of the minimal-volume cycles in certain homology classes that admit no calibrated representatives. In compactification of type IIB string theory on an orientifold X of a Calabi-Yau threefold, we consider a homology class [Σ] ∈ H4(X, ℝ) represented by a union Σ∪ of holomorphic and antiholomorphic cycles. The instanton form of the WGC applied to the axion charge [Σ] implies an upper bound on the action of a non-BPS Euclidean D3-brane wrapping the minimal-volume representative Σmin of [Σ]. We give an explicit example of an orientifold X of a hypersurface in a toric variety, and a hyperplane H ⊂ H4(X, ℝ), such that for any [Σ] ∈ H that satisfies the WGC, the minimal volume obeys Vol (Σmin) ≪ Vol(Σ∪): the holomorphic and antiholomorphic components recombine to form a much smaller cycle. In particular, the sub-Lattice WGC applied to X implies large recombination, no matter how sparse the sublattice. Non-BPS instantons wrapping Σmin are then more important than would be predicted from a study of BPS instantons wrapping the separate components of Σ∪. Our analysis hinges on a novel computation of effective divisors in X that are not inherited from effective divisors of the toric variety.
Health-related quality of life after open and robot-assisted radical prostatectomy in low- and intermediate-risk prostate cancer patients: a propensity score-matched analysis
Authors: Kretschmer Alexander , Bischoff Robert , Chaloupka Michael , Jokisch Friedrich , Westhofen Thilo , Weinhold Philipp , Strittmatter Frank , Becker Armin , Buchner Alexander , Stief Christian G. 
Published: March 2020

Abstract
Purpose
Introduction of robot-assisted radical prostatectomy (RARP) has revolutionized the therapeutic landscape of organ-confined prostate cancer (PCa). However, comparative analyses focused on health-related quality of life (HRQOL) after RARP and open retropubic prostatectomy (ORP) are sparse.

Methods
In the current retrospective analysis,inclusion criteria encompassed PSA ≤ 10 ng/ml, ≤ pT2c, ISUP ≤ 3, age ≤ 65 years, and preoperative continence. A propensity score-matched patient cohort [n = 418 (ORP: 209, RARP: 209)] was created and HRQOL was prospectively assessed based on validated questionnaires (EORTC QLQ-C30) preoperatively, 3 months, 12 months, and 24 months postoperatively. Primary endpoint was good general HRQOL based on previously published cut-off values. Erectile function was measured via IIEF-5, urinary continence via ICIQ-SF questionnaire. Multivariable analysis included binary logistic regression models (p < 0.05).

Results
Open retropubic prostatectomy and RARP cohorts were well balanced. General HRQOL was significantly higher for ORP compared to RARP after 3 months (70.1 vs. 61.6, p = 0.001), but not at the remaining follow-up time points. There were no significant differences for the remaining QLQ-C30 functioning and symptom scores. In multivariable analysis stratified for IIEF-5 and ICIQ-SF scores and surgeon experience, RARP could be confirmed as a marginally independent predictor for lower ratios of good general HRQOL after 3 months (OR 0.464, 95% CI 0.215–0.999; p = 0.050) without any differences at the remaining time points.

Conclusions
The current study addresses various HRQOL outcomes over a postoperative period of up to 2 years in a homogenous propensity score-matched contemporary cohort. Marginally better general HRQOL outcomes could be detected for ORP compared to RARP 3 months postoperatively.
How can 30–60-day ISO move from the South China Sea to Southern China?
Authors: Zheng Bin , Huang Yanyan , Li Chunhui , Lin Ailan 
Published: March 2020

AbstractIn the present study, the northward-propagating intraseasonal oscillations (ISOs) over the South China Sea (SCS) during the summer monsoon season are divided into two types. One is the northward propagation of ISOs confined in the SCS (defined as P1-ISO), another for ISOs moving from the SCS to Southern China (SC) defined as P2-ISO. The spatial and temporal structures of the two types of ISOs are compared based on the analysis of the NCEP–NCAR reanalysis datasets. It is found that a significant difference appears in the heat flux anomalies over SC that is attributed to the cloud-radiation effect. A mechanism associated with the changes in the convective instability is proposed to understand the cause of the northward propagation of the ISO from the SCS to SC. For the P1-ISO, a more precipitation over SC leads to a less surface solar radiation and then a cold land surface temperature (LST), which induces an increase of static stability via surface longwave radiation and sensible heat flux. Whereas the total contribution to the convective instability changes does create an unfavorable for ISOs propagating northward, the moisture convergence, mainly controlled by the baroclinic vorticity advection effect, may contribute to an increase of convective instability that favors the ISOs moving northward. For the P2-ISO, a less precipitation over SC results in a more shortwave radiation reaching the ground that induces a warm LST, and thus leading to a warm low-level air temperature and destabilizing the atmosphere ahead of the convection. Moreover, the moisture convergence, dominated by the warm low-level air temperature, also contributes to the increase of convective instability. Thus the convective instability increment should favor the ISOs moving northward. It is worth noting that the baroclinic vorticity advection and moisture advection are not essential for ISOs propagating from the SCS to SC.
Predictors of the regional variation of prostatectomy or radiotherapy: evidence from German cancer registries
Authors: Medenwald Daniel , Ferencz Julia , Vordermark Dirk 
Published: March 2020

Abstract
Objective
To assess the association of public health parameters with the regional variation in the initial treatment for prostate cancer.

Methods
We used data from German epidemiologic cancer registries for the years 2009–2013. Presence of a certified cancer center, a radiotherapy and/or urology institution, the district-specific GDP, and population density were used as predictors. Patients with indication for adjuvant treatment were excluded (T3b). Only districts with defined quality criteria were eligible. We used general linear mixed models (equivalent to logistic regression) with a covariance matrix weighted by the Euclidean distances between districts. Models were adjusted for age, grading, and TNM stage. We performed sensitivity analyses by imputing missing data with multiple imputation and considering extreme case scenarios. We applied inverse probability weighting to account for missing values.

Results
When radiotherapy/surgery is compared to neither treatment, the probability for the latter was higher in East than in West Germany (OR 1.7, 95% CI 1.43–2.02). The same was true for districts with both, a radiotherapy and urologic treatment facility (OR 1.43, 1.19–1.72). Analyzing radiotherapy vs. surgery, the probability for prostatectomy was inversely associated with the presence of a radiotherapy unit when compared to districts with neither treatment facility (OR 0.52, 95% CI 0.38–0.73). Patients treated in East Germany were more likely to receive a surgical treatment (OR 1.34, 95% CI 1.08–1.66). Sensitivity analyses revealed no relevant change of effect estimates.

Conclusion
Treatment differs between East and West Germany and is associated with the presence of a radiotherapy or urology clinic.
In situ observation of the percolation threshold in multiphase magma analogues
Authors: Colombier M. , Wadsworth F. B. , Scheu B. , Vasseur J. , Dobson K. J. , Cáceres F. , Allabar A. , Marone F. , Schlepütz C. M. , Dingwell D. B. 
Published: March 2020

AbstractMagmas vesiculate during ascent, producing complex interconnected pore networks, which can act as outgassing pathways and then deflate or compact to volcanic plugs. Similarly, in-conduit fragmentation events during dome-forming eruptions create open systems transiently, before welding causes pore sealing. The percolation threshold is the first-order transition between closed- and open-system degassing dynamics. Here, we use time-resolved, synchrotron-source X-ray tomography to image synthetic magmas that go through cycles of opening and closing, to constrain the percolation threshold ΦC at a range of melt crystallinity, viscosity and overpressure pertinent to shallow magma ascent. During vesiculation, we observed different percolative regimes for the same initial bulk crystallinity depending on melt viscosity and gas overpressure. At high viscosity (> 106 Pa s) and high overpressure (~ 1–4 MPa), we found that a brittle-viscous regime dominates in which brittle rupture allows system-spanning coalescence at a low percolation threshold (ΦC~0.17) via the formation of fracture-like bubble chains. Percolation was followed by outgassing and bubble collapse causing densification and isolation of the bubble network, resulting in a hysteresis in the evolution of connectivity with porosity. At low melt viscosity and overpressure, we observed a viscous regime with much higher percolation threshold (ΦC > 0.37) due to spherical bubble growth and lower degree of crystal connection. Finally, our results also show that sintering of crystal-free and crystal-bearing magma analogues is characterised by low percolation thresholds (ΦC = 0.04 – 0.10). We conclude that the presence of crystals lowers the percolation threshold during vesiculation and may promote outgassing in shallow, crystal-rich magma at initial stages of Vulcanian and Strombolian eruptions.
Fractional Sobolev metrics on spaces of immersions
Authors: Bauer Martin , Harms Philipp , Michor Peter W. 
Published: March 2020

AbstractWe prove that the geodesic equations of all Sobolev metrics of fractional order one and higher on spaces of diffeomorphisms and, more generally, immersions are locally well posed. This result builds on the recently established real analytic dependence of fractional Laplacians on the underlying Riemannian metric. It extends several previous results and applies to a wide range of variational partial differential equations, including the well-known Euler–Arnold equations on diffeomorphism groups as well as the geodesic equations on spaces of manifold-valued curves and surfaces.
Models for predicting impact sensitivity of energetic materials based on the trigger linkage hypothesis and Arrhenius kinetics
Authors: Jensen Tomas L. , Moxnes John F. , Unneberg Erik , Christensen Dennis 
Published: March 2020

AbstractIn order to predict the impact sensitivity of high explosives, we designed and evaluated several models based on the trigger linkage hypothesis and the Arrhenius equation. To this effect, we calculated the heat of detonation, temperature of detonation, and bond dissociation energy for 70 energetic molecules. The bond dissociation energy divided by the temperature of detonation proved to be a good predictor of the impact sensitivity of nitroaromatics, with a coefficient of determination (R2) of 0.81. A separate Bayesian analysis gave similar results, taking model complexity into account. For nitramines, there was no relationship between the impact sensitivity and the bond dissociation energy. None of the models studied gave good predictions for the impact sensitivity of liquid nitrate esters. For solid nitrate esters, the bond dissociation energy divided by the temperature of detonation showed promising results (R2 = 0.85), but since this regression was based on only a few data points, it was discredited when model complexity was accounted for by our Bayesian analysis. Since the temperature of detonation correlated with the impact sensitivity for nitroaromatics, nitramines, and nitrate esters, we consider it to be one of the leading predictive factors of impact sensitivity for energetic materials.
Determining Haemodynamic Wall Shear Stress in the Rabbit Aorta In Vivo Using Contrast-Enhanced Ultrasound Image Velocimetry
Authors: Riemer K. , Rowland E. M. , Leow C. H. , Tang M. X. , Weinberg P. D. 
Published: March 2020

AbstractAbnormal blood flow and wall shear stress (WSS) can cause and be caused by cardiovascular disease. To date, however, no standard method has been established for mapping WSS in vivo. Here we demonstrate wide-field assessment of WSS in the rabbit abdominal aorta using contrast-enhanced ultrasound image velocimetry (UIV). Flow and WSS measurements were made independent of beam angle, curvature or branching. Measurements were validated in an in silico model of the rabbit thoracic aorta with moving walls and pulsatile flow. Mean errors over a cardiac cycle for velocity and WSS were 0.34 and 1.69%, respectively. In vivo time average WSS in a straight segment of the suprarenal aorta correlated highly with simulations (PC = 0.99) with a mean deviation of 0.29 Pa or 5.16%. To assess fundamental plausibility of the measurement, UIV WSS was compared to an analytic approximation derived from the Poiseuille equation; the discrepancy was 17%. Mapping of WSS was also demonstrated in regions of arterial branching. High time average WSS (TAWSSxz = 3.4 Pa) and oscillatory flow (OSIxz = 0.3) were observed near the origin of conduit arteries. In conclusion, we have demonstrated that contrast-enhanced UIV is capable of measuring spatiotemporal variation in flow velocity, arterial wall location and hence WSS in vivo with high accuracy over a large field of view.
Insights into the pH-dependent, extracellular sucrose utilization and concomitant levan formation by Gluconobacter albidus TMW 2.1191
Authors: Jakob Frank , Gebrande Clara , Bichler Regina M. , Vogel Rudi F. 
Published: March 2020

AbstractMany bacteria and archaea produce the polydisperse fructose polymer levan from sucrose upon biofilm formation via extracellular levansucrases (EC 2.4.1.10). We have investigated levansucrase-release and -activities as well as molecular size of the levan formed by the acetic acid bacterium Gluconobacter albidus TMW 2.1191 at varying environmental pH conditions to obtain insight in the ecological role of its constitutively expressed levansucrase and the produced levan. A buffer system was established enabling the recovery of levansucrase-containing supernatants from preincubated cell suspensions at pH 4.3–pH 5.7. The enzyme solutions were used to produce levans at different pH values and sucrose concentrations. Finally, the amounts and size distributions of the produced levans as well as the corresponding levansucrase activities were determined and correlated with each other. The data revealed that the levansucrase was released into the environment independently of its substrate sucrose, and that more levansucrase was released at pH ≥ 5.0. The glucose release and formation of high molecular weight levans (> 3.5 kDa) from 0.1 M initial sucrose was comparable between pH ~ 4.3–5.7 using equal amounts of released levansucrase. Hence, this type of levansucrase appears to be structurally adapted to changes in the extracellular pH and to exhibit a similar total activity over a wide acidic pH range, while it produced higher amounts of larger levan molecules at higher production pH and sucrose concentrations. These findings indicate the physiological adaptation of G. albidus TMW 2.1191 to efficient colonisation of sucrose-rich habitats via released levansucrases despite changing extracellular pH conditions in course of acid formation.