julilili42/papers huggingface dataset:
The optical long `period' of LMC X-3
2022-03-19

We have studied the long term variability of LMC X-3 in optical lightcurves spanning six years, in order to search for optical signatures which could confirm/refute the suggestion that the `modulation' is the result of accretion rate variability rather than accretion disc precession. We find that there is no stable period in the optical lightcurves, that the optical and X-ray lightcurves are correlated, with an X-ray lag and that there is no modulation in the optical colours. We argue that these effects agree with the variable mass accretion rate model proposed by Wilms et al. (2001).
Some aspects of the numerical treatment of the conformal field equations
2022-03-19

Some issues in the numerical treatment of the conformal field equations are discussed. In particular, the problem of obtaining smooth initial data for the hyperboloidal initial value problem is described and solution methods are presented.
Abstracts DGU
2022-03-19

Background:Fractures are a major cause of disability, morbidity, and even mortality, particularly in elderly patients, therefore leading to a high economic burden.During fracture healing, the communication between immune cells and bone cells is crucial for the healing outcome.Macrophages represent a large proportion of immune cells with high plasticity present at the site of fracture; thus, they are good target cells for modulation to support the healing process.Interestingly, extremely low-frequency pulsed electromagnet fields (ELF-PEMFs) have been shown to exert cell-specific effects depending on the field conditions.Thus, we intended to identify specific ELF-PEMFs able to modulate macrophage activity to indirectly regulate mesenchymal stem/stromal cell (SCP-1 cells) function and promote fracture healing. Materials and methods:In this study, a two-step blinded screening was performed to find out immunomodulatory ELF-PEMFs from 22 different ELF-PEMFs.According to the influences on monocytes activation and the indirect effects on migration of SCP-1 cells, two fields (termed A and B) were chosen for further experiments.To explore the immunomodulatory effect of field A and field B, the levels of macrophage differentiation phenotype Arginase I, phospho-Stat1, and CD86 were evaluated by Western blot; intracellular reactive oxygen species (ROS) levels were detected with DCFH-DA probe; cytokine secretion was determined with a cytokine array.To verify the indirect influences of field A and field B on fracture healing, SCP-1 cells were cultured with the conditioned medium from the ELF-PEMF exposed macrophages.SCP-1 cell migration was determined as well as expression of extracellular matrix genes. Results:The unblinding showed that field A and field B have similar fundamental frequencies (51.8 Hz and 52.3 Hz) but are emitted in different groups of pulses or rather send-pause intervals.Macrophages exposed to field A showed pro-inflammatory function, represented by increased levels of phospho-Stat1 and CD86, accumulation of ROS, and increased secretion of pro-inflammatory cytokines.In contrast, macrophages exposed to field B showed anti-inflammatory and pro-healing function, represented by increased levels of Arginase I, increased secretion of anti-inflammatory cytokines, and growth factors known to induce healing processes.The conditioned medium from macrophages exposed to both ELF-PEMFs favored migration of SCP-1 cells, but the effect was stronger for field B. Furthermore, the conditioned medium from macrophages exposed to field B, but not to field A, stimulated expression of extracellular matrix genes in SCP-1 cells; i.e., COL1A1, FN1, and BGN. Conclusion:Our data show that specific ELF-PEMFs may affect immune cell function.Thus, knowing the specific ELF-PEMF conditions and underlying mechanisms bears great potential as an adjuvant treatment to modulate immune responses to support healing outcomes.
Abstracts DGKCH
2022-03-19

Background:In pediatric patients, esophageal perforation (EP) is rare but associated with significant morbidity and mortality rates of up to 20-30%.In addition to standard treatment options, endoscopic esophageal vacuum-assisted closure (EVAC) therapy has shown promising results, especially in adult patients.Thus far, the only data on technical success and effectiveness of EVAC in pediatric patients were published in 2018 by Manfredi et al. at Boston Children's Hospital.The sparse data on EVAC in children indicates that this promising technique has been barely utilized in pediatric patients.More data are needed to evaluate efficacy and outcomes of this technique in pediatric patients. Materials and methods:We reviewed five cases of therapy using EVAC, ArgyleTM Replogle Suction Catheter (RSC), or both on pediatric patients with EP in our institution between October 2018 and April 2020. Results:Five patients with EP (median 3.4 years; 2 males) were treated with EVAC, RSC, or a combination.Complete closure of EP was not achieved after EVAC alone, though patients' health stabilized and inflammation and size of EP decreased after EVAC.Four patients then were treated with RSC until the EP healed.One patient needed surgery as the recurrent fistula did not heal sufficiently after 3 weeks of EVAC therapy.Two patients developed stenosis and were successfully treated with dilatations.One patient treated with RSC alone showed persistent EP after 5 weeks. Conclusion:EVAC in pediatric patients is technically feasible and a promising method to treat EP, regardless of the underlying cause.EVAC therapy can be terminated as soon as local inflammation and C-reactive protein levels decrease, even if the mucosa is not healed completely at that time.A promising subsequent treatment is RSC.An earlier switch to RSC can substantially reduce the need of anesthesia during subsequent treatments.Our findings indicate that EVAC is more effective than RSC alone.In some cases, EVAC can be used to improve the tissues condition in preparation for a re-do surgery.At 1 year after therapy, all but one patient demonstrated sufficient weight gain.Further prospective studies with a larger cohort are required to confirm our observations from this small case series.
Self-Similar Measures for Quasicrystals
2022-03-19

We study self-similar measures of Hutchinson type, defined by compact families of contractions, both in a single and multi-component setting. The results are applied in the context of general model sets to infer, via a generalized version of Weyl's Theorem on uniform distribution, the existence of invariant measures for families of self-similarities of regular model sets.
Center vortex model for nonperturbative strong interaction physics
2022-03-19

A model for the infrared sector of SU(2) Yang-Mills theory, based on magnetic vortex degrees of freedom represented by (closed) random world-surfaces, is presented. The model quantitatively describes both the confinement properties (including the finite-temperature transition to a deconfined phase) and the topological susceptibility of the Yang-Mills ensemble. A (quenched) study of the spectrum of the Dirac operator furthermore yields a behavior for the chiral condensate which is compatible with results obtained in lattice gauge theory.
Classification in Feature-based Default Inheritance Hierarchies
2022-03-19

Increasingly, inheritance hierarchies are being used to reduce redundancy in natural language processing lexicons. Systems that utilize inheritance hierarchies need to be able to insert words under the optimal set of classes in these hierarchies. In this paper, we formalize this problem for feature-based default inheritance hierarchies. Since the problem turns out to be NP-complete, we present an approximation algorithm for it. We show that this algorithm is efficient and that it performs well with respect to a number of standard problems for default inheritance. A prototype implementation has been tested on lexical hierarchies and it has produced encouraging results. The work presented here is also relevant to other types of default hierarchies.
Complete Q ‐matrices in conjunctive models on general attribute structures
2022-03-20

In cognitive diagnostic assessment a property of the Q ‐matrix, usually referred to as completeness, warrants that the cognitive attributes underlying the observed behaviour can be uniquely assessed. Characterizations of completeness were first derived under the assumption of independent attributes, and are currently under investigation for interdependent attributes. The dominant approach considers so‐called attribute hierarchies, which are conceptualized through a partial order on the set of attributes. The present paper extends previously published results on this issue obtained for conjunctive attribute hierarchy models. Drawing upon results from knowledge structure theory, it provides novel sufficient and necessary conditions for completeness of the Q ‐matrix, not only for conjunctive models on attribute hierarchies, but also on more general attribute structures.
Manin's conjecture for toric varieties
2022-03-20

We prove an asymptotic formula conjectured by Manin for the number of -rational points of bounded height with respect to the anticanonical line bundle for arbitrary smooth projective toric varieties over a number field .
An Approach to Proper Name Tagging for German
2022-03-20

This paper presents an incremental method for the tagging of proper names in German newspaper texts. The tagging is performed by the analysis of the syntactic and textual contexts of proper names together with a morphological analysis. The proper names selected by this process supply new contexts which can be used for finding new proper names, and so on. This procedure was applied to a small German corpus (50,000 words) and correctly disambiguated 65% of the capitalized words, which should improve when it is applied to a very large corpus.
Vela X-1 as seen by RXTE
2022-03-20

We present results from four observations of the accreting X-ray pulsar Vela X-1 with RXTE in 1996 February. The light curves show strong pulse to pulse variations, while the average pulse profiles are quite stable, similar to previous results. Below 5keV the pulse profiles display a complex, 5-peaked structure with a transition to a simple, double peak above about 15keV. We analyze phase-averaged, phase-resolved, and on-pulse minus off-pulse spectra. The best spectral fits were obtained using continuum models with a smooth high-energy turnover. In contrast, the commonly used power law with exponential cutoff introduced artificial features in the fit residuals. Using a power law with a Fermi-Dirac cutoff modified by photoelectric absorption and an iron line, the best fit spectra are still unacceptable. We interpret large deviations around 25 and 55keV as fundamental and second harmonic cyclotron absorption lines. If this result holds true, the ratio of the line energies seems to be larger than 2. Phase resolved spectra show that the cyclotron lines are strongest on the main pulse while they are barely visible outside the pulses.
On Implementing an HPSG theory -- Aspects of the logical architecture, the formalization, and the implementation of head-driven phrase structure grammars
2022-03-20

The paper presents some aspects involved in the formalization and implementation of HPSG theories. As basis, the logical setups of Carpenter (1992) and King (1989, 1994) are briefly compared regarding their usefulness as basis for HPSGII (Pollard and Sag 1994). The possibilities for expressing HPSG theories in the HPSGII architecture and in various computational systems (ALE, Troll, CUF, and TFS) are discussed. Beside a formal characterization of the possibilities, the paper investigates the specific choices for constraints with certain linguistic motivations, i.e. the lexicon, structure licencing, and grammatical principles. An ALE implementation of a theory for German proposed by Hinrichs and Nakazawa (1994) is used as example and the ALE grammar is included in the appendix.
A Computational Treatment of HPSG Lexical Rules as Covariation in Lexical Entries
2022-03-20

We describe a compiler which translates a set of HPSG lexical rules and their interaction into definite relations used to constrain lexical entries. The compiler ensures automatic transfer of properties unchanged by a lexical rule. Thus an operational semantics for the full lexical rule mechanism as used in HPSG linguistics is provided. Program transformation techniques are used to advance the resulting encoding. The final output constitutes a computational counterpart of the linguistic generalizations captured by lexical rules and allows ``on the fly'' application.
What the Infrared Behavior of QCD Green Functions can tell us about Confinement in the Covariant Gauge
2022-03-20

We review aspects of confinement in the covariant and local description of QCD and discuss to what extend our present knowledge of the infrared behavior of QCD Green functions can support this description. In particular, we emphasize: the positivity violations of transverse gluon and quark states, the Kugo-Ojima confinement criterion, and the conditions necessary to avoid the decomposition property for colored clusters. We summarize how these issues relate to the infrared behavior of the propagators in Landau gauge QCD as extracted from solutions to truncated Dyson-Schwinger equations and lattice simulations.
Compiling HPSG type constraints into definite clause programs
2022-03-20

We present a new approach to HPSG processing: compiling HPSG grammars expressed as type constraints into definite clause programs. This provides a clear and computationally useful correspondence between linguistic theories and their implementation. The compiler performs off-line constraint inheritance and code optimization. As a result, we are able to efficiently process with HPSG grammars without having to hand-translate them into definite clause or phrase structure based systems.
The Classical Stellar Atmosphere Problem
2022-03-20

We introduce the classical stellar atmosphere problem and describe in detail its numerical solution. The problem consists of the solution of the radiation transfer equations under the constraints of hydrostatic, radiative and statistical equilibrium (non-LTE). We outline the basic idea of the Accelerated Lambda Iteration (ALI) technique and statistical methods which finally allow the construction of non-LTE model atmospheres considering the influence of millions of metal absorption lines. Some applications of the new models are presented.
Center vortex model for the infrared sector of Yang-Mills theory
2022-03-20

A model for the infrared sector of SU(2) Yang-Mills theory, based on magnetic vortices represented by (closed) random surfaces, is presented. The random surfaces, governed by an action penalizing curvature, are investigated using Monte Carlo methods on a hypercubic lattice. A low-temperature confining phase and a high-temperature deconfined phase are generated by this simple dynamics. After fixing the parameters of the model such as to reproduce the relation between deconfinement temperature and zero-temperature string tension found in lattice Yang-Mills theory, a surprisingly accurate prediction of the spatial string tension in the deconfined phase results. Furthermore, the Pontryagin index associated with the lattice random surfaces of the model is constructed. This allows to also predict the topological susceptibility; the result is compatible with measurements in lattice Yang-Mills theory. Thus, for the first time an effective model description of the infrared sector emerges which simultaneously and consistently reproduces both confinement and the topological aspects of Yang-Mills theory within a unified framework. Further details can be found in hep-lat/9912003 and hep-lat/0004013, both to appear in Nucl. Phys. B.
Pion Exchange Currents in Neutrinoless Double Beta Decay and Limits on Supersymmetry
2022-03-20

We examine the pion exchange mode of neutrinoless double beta decay induced by the R-parity violating quark-lepton operators of the supersymmetric (SUSY) extensions of the standard model of the electroweak interactions. The corresponding nuclear matrix elements are evaluated within the renormalized quasiparticle random phase approximation with proton-neutron pairing, which includes the Pauli effect of fermion pairs and does not collapse for a physical value of the nuclear force strength. It is argued that the pion-exchange mode of neutrinoless double beta decay dominates over the conventional two-nucleon mode in the case of the SUSY mechanism. As a result sensitivity of neutrinoless double beta decay to the SUSY contribution turns out to be significantly better that previously expected from the two-nucleon mode calculations. An upper limit on the R-parity violating coupling is derived from non-observation of neutrinoless double beta decay. This limit is much stronger than that expected from the near future accelerator experiments.
Implementation and evaluation of a German HMM for POS disambiguation
2022-03-20

A German language model for the Xerox HMM tagger is presented. This model's performance is compared with two other German taggers with partial parameter re-estimation and full adaption of parameters from pre-tagged corpora. The ambiguity types resolved by this model are analysed and compared to ambiguity types of English and French. Finally, the model's error types are described. I argue that although the overall performance of these models for German is comparable to results for English and French, a more exact analysis demonstrates important differences in the types of disambiguation involved for German.
Pulse Phase Spectroscopy of A 0535+26 during its 1994 giant outburst observed with OSSE
2022-03-20

We present pulse phase spectroscopy of A 0535+26 in the energy range 35-200 keV from OSSE observations of its giant outburst in 1994. We discuss the phase dependence of the continuum parameters and the cyclotron resonance feature (CRF) at 110 keV already found in the phase averaged spectrum. We find that a CRF is required at every phase. The behaviour of the line parameters with phase and the pulse shape indicate that the emission occurs in a pencil-beam geometry.
The EUV spectrum of the unique bare stellar core H1504+65
2022-03-20

We performed a spectral analysis of the EUVE spectrum and ROSAT data of the unique object H1504+65, which is an extremely hot post-AGB star entering the white dwarf cooling sequence. It is the only pre-white dwarf known, whose surface is free of hydrogen and helium, hence, it represents the bare core of a former AGB star. The EUV spectrum (75--150A) is dominated by strong OVI lines and we can identify a number of NeVII lines. EUVE and ROSAT data can be fitted with models between Teff=170000 K and 200000 K. We derive an extraordinarily high neon abundance (2%--5% by mass, i.e. 20--50 times solar) which we confirm by an optical NeVII line detected in a Keck HIRES echelle spectrum. This abundance is expected for 3-alpha processed matter and corroborates our understanding of H1504+65 as a C-O stellar core which has lost its entire H- and He-rich envelopes.
Evasion and prediction II
2022-03-20

A subgroup G \\leq Z^omega exhibits the Specker phenomenon if every homomorphism G \\to Z maps almost all unit vectors to 0. We give several combinatorial characterizations of the cardinal se, the size of the smallest G \\leq Z^omega exhibiting the Specker phenomenon. We also prove the consistency of b &lt; e, where b is the unbounding number and e the evasion number introduced recently by Blass. Finally we show that e \\geq \\min { aleph_0--e , cov(M) }, where aleph_0--e is the aleph_0--evasion number (the uniformity of the evasion ideal) and cov(M) is the covering number of the meager ideal. All these results can be dualized. They answer several questions addressed by Blass.
Formalization and Parsing of Typed Unification-Based ID/LP Grammars
2022-03-20

This paper defines unification based ID/LP grammars based on typed feature structures as nonterminals and proposes a variant of Earley's algorithm to decide whether a given input sentence is a member of the language generated by a particular typed unification ID/LP grammar. A solution to the problem of the nonlocal flow of information in unification ID/LP grammars as discussed in Seiffert (1991) is incorporated into the algorithm. At the same time, it tries to connect this technical work with linguistics by presenting an example of the problem resulting from HPSG approaches to linguistics (Hinrichs and Nakasawa 1994, Richter and Sailer 1995) and with computational linguistics by drawing connections from this approach to systems implementing HPSG, especially the TROLL system, Gerdemann et al. (forthcoming).
RXTE Observation of Cygnus X--1: III. Implications for Compton Corona and ADAF Models
2022-03-20

We have recently shown that a `sphere+disk' geometry Compton corona model provides a good description of Rossi X-ray Timing Explorer (RXTE) observations of the hard/low state of Cygnus X--1. Separately, we have analyzed the temporal data provided by RXTE. In this paper we consider the implications of this timing analysis for our best-fit `sphere+disk' Comptonization models. We focus our attention on the observed Fourier frequency-dependent time delays between hard and soft photons. We consider whether the observed time delays are: created in the disk but are merely reprocessed by the corona; created by differences between the hard and soft photon diffusion times in coronae with extremely large radii; or are due to `propagation' of disturbances through the corona. We find that the time delays are most likely created directly within the corona; however, it is currently uncertain which specific model is the most likely explanation. Models that posit a large coronal radius [or equivalently, a large Advection Dominated Accretion Flow (ADAF) region] do not fully address all the details of the observed spectrum. The Compton corona models that do address the full spectrum do not contain dynamical information. We show, however, that simple phenomenological propagation models for the observed time delays for these latter models imply extremely slow characteristic propagation speeds within the coronal region.
NLTE Model Atmospheres for Central Stars of Planetary Nebulae
2022-03-20

Present observational techniques provide stellar spectra with high resolution at a high signal-to-noise ratio over the complete wavelength range -- from the far infrared to the X-ray. NLTE effects are particularly important for hot stars, hence the use of reliable NLTE stellar model atmosphere fluxes is required for an adequate spectral analysis. State-of-the-art NLTE model atmospheres include the metal-line blanketing of millions of lines of all elements from hydrogen up to the iron-group elements and thus permit precise analyses of extremely hot compact stars, e.g. central stars of planetary nebulae, PG 1159 stars, white dwarfs, and neutron stars. Their careful spectroscopic study is of great interest in several branches of modern astrophysics, e.g. stellar and galactic evolution, and interstellar matter.
Models of Superconductivity in Sr_2RuO_4
2022-03-20

Recent experimental data on purest Sr_2RuO_4 single crystals clearly indicate the presence of nodes in the superconducting order parameter. Here, we consider one special p-wave order parameter symmetry and two two-dimensional f-wave order parameter symmetries having nodes within the RuO_2 plane. These states reasonably describe both specific heat and penetration depth data. We calculate the thermal conductivity tensor for these three states and compare the results with recent thermal conductivity data. This allows us to single out one of these states being consistent with both thermodynamic and thermal conductivity data: the planar f-wave state having B_{1g} x E_u symmetry.