bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analog‐based post‐processing of the ALADIN‐LAEF ensemble predictions in complex terrain
Authors: Odak Plenković Iris , Schicker Irene , Dabernig Markus , Horvath Kristian , Keresturi Endi 
Published: February 2020

AbstractThe main goal of this study is to assess the performance of the analog‐based post‐processing method applied to the Austrian ALADIN‐LAEF wind speed ensemble predictions through a set of sensitivity experiments. Evaluation of several analog‐based configurations using various meteorological variables as predictors is therefore conducted. The results of those experiments are compared to the ensemble model output statistics (EMOS) baseline model. The hypothesis further investigated is that using summarized measures, such as mean and standard deviation of an ensemble for several meteorological variables, is comparable to the analog post‐processing using all of the ensemble members. Results show that both analog‐based and EMOS experiments considerably improve the raw model forecast. Even though the improvement over raw model forecast is evident, large differences among nearby stations are noticed in the highly complex terrain. The processes at lower stations seem to be better represented by the raw model, which leads to a better input forecast to the post‐processing and a better overall result than for the mountain stations. The analog‐based method is overall comparable to or even outperforms the EMOS. Assessing the post‐processing performance for high wind speeds shows that the analog experiments can improve the raw forecast, exhibiting significantly higher skill than the EMOS. The difference among all analog experiments is less pronounced, especially the experiment using all of the raw model ensemble members and the one using summarized measures. Furthermore, it is demonstrated that the usage of summarized ensemble measures is an optimal way to improve the forecast skill, compared to the other analog‐based experiments and the EMOS model. Therefore, it is suggested that it is not necessary to increase the computational costs by using the full input spectrum of a raw probabilistic model, that is, all ALADIN‐LAEF members as predictors, as the summarized metric suffices.
$$ \mathcal{N} $$-extended Chern-Simons Carrollian supergravities in 2 + 1 spacetime dimensions
Authors: Ali Farhad , Ravera Lucrezia 
Published: February 2020

Abstract
In this work we present the ultra-relativistic $$ \mathcal{N} $$
N
-extended AdS Chern-Simons supergravity theories in three spacetime dimensions invariant under $$ \mathcal{N} $$
N
-extended AdS Carroll superalgebras. We first consider the (2, 0) and (1, 1) cases; subsequently, we generalize our analysis to $$ \mathcal{N} $$
N
= ($$ \mathcal{N} $$
N
, 0), with $$ \mathcal{N} $$
N
even, and to $$ \mathcal{N} $$
N
= (p, q), with p, q > 0. The $$ \mathcal{N} $$
N
-extended AdS Carroll superalgebras are obtained through the Carrollian (i.e., ultra-relativistic) contraction applied to an so(2) extension of $$ \mathfrak{osp} $$
osp
(2|2) ⊗ $$ \mathfrak{sp} $$
sp
(2), to $$ \mathfrak{osp} $$
osp
(2|1) ⊗ $$ \mathfrak{osp} $$
osp
(2, 1), to an $$ \mathfrak{so}\left(\mathcal{N}\right) $$
so

N

extension of $$ \mathfrak{osp} $$
osp
(2|$$ \mathcal{N} $$
N
) ⊗ $$ \mathfrak{sp} $$
sp
(2), and to the direct sum of an $$ \mathfrak{so} $$
so
(p) ⊕ $$ \mathfrak{so} $$
so
(q) algebra and $$ \mathfrak{osp} $$
osp
(2|p) ⊗ $$ \mathfrak{osp} $$
osp
(2, q), respectively. We also analyze the flat limit (ℓ → ∞, being ℓ the length parameter) of the aforementioned $$ \mathcal{N} $$
N
-extended Chern-Simons AdS Carroll supergravities, in which we recover the ultra-relativistic $$ \mathcal{N} $$
N
-extended (flat) Chern-Simons supergravity theories invariant under $$ \mathcal{N} $$
N
-extended super-Carroll algebras. The flat limit is applied at the level of the superalgebras, Chern-Simons actions, supersymmetry transformation laws, and field equations.
O new physics, where art thou? A global search in the top sector
Authors: Brivio Ilaria , Bruggisser Sebastian , Maltoni Fabio , Moutafis Rhea , Plehn Tilman , Vryonidou Eleni , Westhoff Susanne , Zhang Cen 
Published: February 2020

Abstract
We provide a comprehensive global analysis of Run II top measurements at the LHC in terms of dimension-6 operators. A distinctive feature of the top sector as compared to the Higgs-electroweak sector is the large number of four-quark operators. We discuss in detail how they can be tested and how quadratic terms lead to a stable limit on each individual Wilson coefficient. Predictions for all observables are computed at NLO in QCD. Our SFitter analysis framework features a detailed error treatment, including correlations between uncertainties.
Absorption of fermionic dark matter by nuclear targets
Authors: Dror Jeff A. , Elor Gilly , McGehee Robert 
Published: February 2020

Abstract
Absorption of fermionic dark matter leads to a range of distinct and novel signatures at dark matter direct detection and neutrino experiments. We study the possible signals from fermionic absorption by nuclear targets, which we divide into two classes of four Fermi operators: neutral and charged current. In the neutral current signal, dark matter is absorbed by a target nucleus and a neutrino is emitted. This results in a characteristically different nuclear recoil energy spectrum from that of elastic scattering. The charged current channel leads to induced β decays in isotopes which are stable in vacuum as well as shifts of the kinematic endpoint of β spectra in unstable isotopes. To confirm the possibility of observing these signals in light of other constraints, we introduce UV completions of example higher dimensional operators that lead to fermionic absorption signals and study their phenomenology. Most prominently, dark matter which exhibits fermionic absorption signals is necessarily unstable leading to stringent bounds from indirect detection searches. Nevertheless, we find a large viable parameter space in which dark matter is sufficiently long lived and detectable in current and future experiments.
Deriving the AdS3/CFT2 correspondence
Authors: Eberhardt Lorenz , Gaberdiel Matthias R. , Gopakumar Rajesh 
Published: February 2020

Abstract
It was recently argued that string theory on AdS3× S3× 𝕋4 with one unit (k = 1) of NS-NS flux is exactly dual to the symmetric orbifold CFT SymN (𝕋4). In this paper we show how to directly relate the n-point correlators of the two sides to one another. In particular, we argue that the correlators of the world-sheet theory are delta-function- localised in string moduli space to those configurations that allow for a holomorphic covering map of the S2-boundary of AdS3 by the world-sheet. This striking feature can be seen both from a careful Ward identity analysis, as well as from semi-classically exact AdS3 solutions that are pinned to the boundary. The world-sheet correlators therefore have exactly the same structure as in the Lunin-Mathur construction of symmetric orbifold CFT correlators in terms of a covering surface — which now gets identified with the world-sheet. Together with the results of [1, 2] this essentially demonstrates how the k = 1 AdS3 string theory becomes equivalent to the spacetime orbifold CFT in the genus expansion.
Field theories on null manifolds
Authors: Bagchi Arjun , Basu Rudranil , Mehra Aditya , Nandi Poulami 
Published: February 2020

Abstract
We argue that generic field theories defined on null manifolds should have an emergent BMS or conformal Carrollian structure. We then focus on a simple interacting conformal Carrollian theory, viz. Carrollian scalar electrodynamics. We look at weak (on-shell) and strong invariance (off-shell) of its equations of motion under conformal Carrollian symmetries. Helmholtz conditions are necessary and sufficient conditions for a set of equations to arise from a Lagrangian. We investigate whether the equations of motion of Carrollian scalar electrodynamics satisfy these conditions. Then we proposed an action for the electric sector of the theory. This action is the first example for an interacting conformal Carrollian Field Theory. The proposed action respects the finite and infinite conformal Carrollian symmetries in d = 4. We calculate conserved charges corresponding to these finite and infinite symmetries and then rewrite the conserved charges in terms of the canonical variables. We finally compute the Poisson brackets for these charges and confirm that infinite Carrollian conformal algebra is satisfied at the level of charges.
Tensor hierarchy algebras and extended geometry. Part I. Construction of the algebra
Authors: Cederwall Martin , Palmkvist Jakob 
Published: February 2020

Abstract
Tensor hierarchy algebras constitute a class of non-contragredient Lie superalgebras, whose finite-dimensional members are the “Cartan-type” Lie superalgebras in Kac’s classification. They have applications in mathematical physics, especially in extended geometry and gauged supergravity. We further develop the recently proposed definition of tensor hierarchy algebras in terms of generators and relations encoded in a Dynkin diagram (which coincides with the diagram for a related Borcherds superalgebra). We apply it to cases where a grey node is added to the Dynkin diagram of a rank r + 1 Kac-Moody algebra $$ \mathfrak{g} $$
g
+, which in turn is an extension of a rank r finite-dimensional semisimple simply laced Lie algebra $$ \mathfrak{g} $$
g
. The algebras are specified by $$ \mathfrak{g} $$
g
together with a dominant integral weight λ. As a by-product, a remarkable identity involving representation matrices for arbitrary integral highest weight representations of $$ \mathfrak{g} $$
g
is proven. An accompanying paper [1] describes the application of tensor hierarchy algebras to the gauge structure and dynamics in models of extended geometry.
Excitation Features of Speech for Emotion Recognition Using Neutral Speech as Reference
Authors: Kadiri Sudarsana Reddy , Gangamohan P. , Gangashetty Suryakanth V. , Alku Paavo , Yegnanarayana B. 
Published: February 2020

AbstractIn generation of emotional speech, there are deviations in the speech production features when compared to neutral (non-emotional) speech. The objective of this study is to capture the deviations in features related to the excitation component of speech and to develop a system for automatic recognition of emotions based on these deviations. The emotions considered in this study are anger, happiness, sadness and neutral state. The study shows that there are useful features in the deviations of the excitation features, which can be exploited to develop an emotion recognition system. The excitation features used in this study are the instantaneous fundamental frequency ($$F_0$$F0), the strength of excitation, the energy of excitation and the ratio of the high-frequency to low-frequency band energy ($$\beta $$β). A hierarchical binary decision tree approach is used to develop an emotion recognition system with neutral speech as reference. The recognition experiments showed that the excitation features are comparable or better than the existing prosody features and spectral features, such as mel-frequency cepstral coefficients, perceptual linear predictive coefficients and modulation spectral features.
Integrability Analysis of the Stretch–Twist–Fold Flow
Authors: Maciejewski Andrzej J. , Przybylska Maria 
Published: February 2020

AbstractWe study the integrability of an eight-parameter family of three-dimensional spherically confined steady Stokes flows introduced by Bajer and Moffatt. This volume-preserving flow was constructed to model the stretch–twist–fold mechanism of the fast dynamo magnetohydrodynamical model. In particular we obtain a complete classification of cases when the system admits an additional Darboux polynomial of degree one. All but one such case are integrable, and first integrals are presented in the paper. The case when the system admits an additional Darboux polynomial of degree one but is not evidently integrable is investigated by methods of differential Galois theory. It is proved that the four-parameter family contained in this case is not integrable in the Jacobi sense, i.e. it does not admit a meromorphic first integral. Moreover, we investigate the integrability of other four-parameter $${\textit{STF}}$$STF systems using the same methods. We distinguish all the cases when the system satisfies necessary conditions for integrability obtained from an analysis of the differential Galois group of variational equations.
Microstructure Investigations of Powders and Additive Manufactured Parts
Authors: Albu M. , Mitsche S. , Nachtnebel M. , Krisper R. , Dienstleder M. , Schröttner H. , Kothleitner G. 
Published: February 2020

AbstractThis paper presents an advanced microstructural analysis of the AlSiMg, Ti64, and N700 powders used for additive manufacturing. The internal microstructure of the regular and irregular powder grains were characterized down to atomic resolution by using scanning electron microscopy and high resolution scanning transmission electron microscopy.The accretionary forms on top of the irregular AlSiMg powder grains exhibit a slightly coarse microstructure with a network of eutectic Si consisting of nano-crystallites, suggesting a slower cooling than the grain itself that contain a predominately amorphous Si network.A nm thin amorphous C layer on the surface of some Ti64 plasma atomized powder grains promoted the attachment of satellites and growth of envelopes. In case of gas atomized N700 powder grains, we identified thin oxide and carbon amorphous layers as well as metal segregations at the interface between the grain body and the accretionary forms.
Improving access to services for psychotic patients: does implementing a waiting time target make a difference
Authors: Kreutzberg Anika , Jacobs Rowena 
Published: February 2020

AbstractObjectiveIn April 2015, the English National Health Service started implementing the first waiting time targets in mental health care. This study aims to investigate the effect of the 14-day waiting time target for early intervention in psychosis (EIP) services after the first six months of its implementation.Study designWe analyse a cohort of first-episode psychosis patients from the English administrative Mental Health and Learning Disabilities Dataset 2011 to 2015. We compare patients being treated by EIP services (treatment) with those receiving care from standard community mental health services (control). We combine non-parametric matching with a difference-in-difference approach to account for observed and unobserved group differences. We analyse the probability of waiting below target and look at different percentiles of the waiting time distribution.ResultsEIP patients had an 11.6–18.4 percentage point higher chance of waiting below target post-policy compared to standard care patients. However, post-policy trends at different percentiles of the waiting time distribution were not different between groups.ConclusionsMental health providers seem to respond to waiting time targets in a similar way as physical health providers. The increased proportion waiting below target did not, however, result in an overall improvement across the waiting time distribution.
Testing bat abundance and diversity predictions by PREBAT, a connectivity-based habitat suitability model for insectivorous bats
Authors: von Hirschheydt Gesa , Kindvall Oskar , de Jong Johnny 
Published: February 2020

AbstractWhere large landscape modifications are planned, e.g. for infrastructure or exploitation, ecological impact assessments are required because of their potential effects on environment and species. Methods that make such assessments more standardized, efficient, and reliable are highly desirable. This paper proposes a new connectivity-based habitat model for bats (PREBAT), which could be used as a tool for impact assessments. Using data that was specifically collected for this purpose, the performance of PREBAT is critically analyzed and discussed. For this study, 50 sites within an area of 850 km2in eastern Sweden were inventoried for four nights each using automatic ultrasound recorders to get an empiric measure of bat occurrence that could be compared with PREBAT predictions. The correlation between the predicted values from PREBAT and the observed bat activity (number of recordings) or species richness was tested using generalized linear mixed models. Predicted values of PREBAT are significantly correlated to the number of species that regularly (more than one night) occur at a given site, but not to the total number of species. PREBAT performed also much better at predicting the activity of forest-living species than overall bat activity, which makes PREBAT particularly suitable for predicting conflicts for those species. This study proposes a new habitat model for bats that takes spatial connectivity between habitat patches into account. PREBAT is shown to perform satisfyingly and has the potential to become a useful tool in assessing the ecological impact of large-scale landscape modifications.
Altruism, fast and slow? Evidence from a meta-analysis and a new experiment
Authors: Fromell Hanna , Nosenzo Daniele , Owens Trudy 
Published: February 2020

AbstractCan we use the lens of dual-system theories to explain altruistic behavior? In recent years this question has attracted the interest of both economists and psychologists. We contribute to this emerging literature by reporting the results of a meta-study of the literature and a new experiment. Our meta-study is based on 22 experimental studies conducted with more than 12,000 subjects. We show that the overall effect of manipulating cognitive resources to promote the “intuitive” system at the expense of the “deliberative” system is very close to zero. One reason for this null result could be that promoting intuition has heterogeneous effects on altruism across different subgroups of subjects or contexts. Another reason could be that there simply is no real effect and that previously reported single results are false positives. We explore the role of heterogeneity both by performing a mediator analysis of the meta-analytic effect and by conducting a new experiment designed to circumvent the issue of potential heterogeneity in the direction of the effect of promoting intuition. In both cases, we find little evidence that heterogeneity explains the absence of an overall effect of intuition on altruism. Taken together, our results offer little support for dual-system theories of altruistic behavior.
A simple method for quantifying iodate and iodide fractions in solution using Ag+-impregnated activated carbon
Authors: Suorsa Valtteri , Otaki Miho , Zhang Wenzhong , Virkanen Juhani , Koivula Risto 
Published: February 2020

AbstractThe speciation of iodine in environment must be known in order to properly assess its geological fate and to study potential remediation materials for the decontamination of water containing radioactive iodine. In this study, the utilization of silver-impregnated granular activated carbon for separation between two iodine species, iodate and iodide, from each other was studied in different solution matrices with batch and column experiments. A high separation of the iodine species was achieved in the high concentrations of interfering ions, e.g. chloride, and in both μM and trace iodine concentrations. The method is suitable for both radioactive and non-radioactive iodine.
Perpendicular Transport of Energetic Particles in Magnetic Turbulence
Authors: Shalchi Andreas 
Published: February 2020

AbstractScientists have explored how energetic particles such as solar energetic particles and cosmic rays move through a magnetized plasma such as the interplanetary and interstellar medium since more than five decades. From a theoretical point of view, this topic is difficult because the particles experience complicated interactions with turbulent magnetic fields. Besides turbulent fields, there are also large scale or mean magnetic fields breaking the symmetry in such systems and one has to distinguish between transport of particles parallel and perpendicular with respect to such mean fields. In standard descriptions of transport phenomena, one often assumes that the transport in both directions is normal diffusive but non-diffusive transport was found in more recent work. This is in particular true for early and intermediate times where the diffusive regime is not yet reached. In recent years researchers employed advanced numerical tools in order to simulate the motion of those particles through the aforementioned systems. Nevertheless, the analytical description of the problem discussed here is of utmost importance since analytical forms of particle transport parameters need to be known in several applications such as solar modulation studies or investigations of shock acceleration. The latter process is directly linked to the question of what the sources of high energy cosmic rays are, a problem which is considered to be one of the most important problems of the sciences of the 21st century. The present review article discusses analytical theories developed for describing particle transport across a large scale magnetic field as well as field line random walk. A heuristic approach explaining the basic physics of perpendicular transport is also presented. Simple analytical forms for the perpendicular diffusion coefficient are proposed which can easily be incorporated in numerical codes for solar modulation or shock acceleration studies. Test-particle simulations are also discussed together with a comparison with analytical results. Several applications such as cosmic ray propagation and diffusive shock acceleration are also part of this review.
Design of an end-effector for robot-assisted ultrasound-guided breast biopsies
Authors: Welleweerd Marcel K. , Siepel Françoise J. , Groenhuis Vincent , Veltman Jeroen , Stramigioli Stefano 
Published: February 2020

Abstract
Purpose
The biopsy procedure is an important phase in breast cancer diagnosis. Accurate breast imaging and precise needle placement are crucial in lesion targeting. This paper presents an end-effector (EE) for robotic 3D ultrasound (US) breast acquisitions and US-guided breast biopsies. The EE mechanically guides the needle to a specified target within the US plane. The needle is controlled in all degrees of freedom (DOFs) except for the direction of insertion, which is controlled by the radiologist. It determines the correct needle depth and stops the needle accordingly.

Method
In the envisioned procedure, a robotic arm performs localization of the breast, 3D US volume acquisition and reconstruction, target identification and needle guidance. Therefore, the EE is equipped with a stereo camera setup, a picobeamer, US probe holder, a three-DOF needle guide and a needle stop. The design was realized by prototyping techniques. Experiments were performed to determine needle placement accuracy in-air. The EE was placed on a seven-DOF robotic manipulator to determine the biopsy accuracy on a cuboid phantom.

Results
Needle placement accuracy was 0.3 ± 1.5 mm in and 0.1 ± 0.36 mm out of the US plane. Needle depth was regulated with an accuracy of 100 µm (maximum error 0.89 mm). The maximum holding force of the stop was approximately 6 N. The system reached a Euclidean distance error of 3.21 mm between the needle tip and the target and a normal distance of 3.03 mm between the needle trajectory and the target.

Conclusion
An all in one solution was presented which, attached to a robotic arm, assists the radiologist in breast cancer imaging and biopsy. It has a high needle placement accuracy, yet the radiologist is in control like in the conventional procedure.