64 research outputs found
Moments of meson spectral functions in vacuum and nuclear matter
Moments of the meson spectral function in vacuum and in nuclear matter
are analyzed, combining a model based on chiral SU(3) effective field theory
(with kaonic degrees of freedom) and finite-energy QCD sum rules. For the
vacuum we show that the spectral density is strongly constrained by a recent
accurate measurement of the cross section. In nuclear
matter the spectrum is modified by interactions of the decay kaons with
the surrounding nuclear medium, leading to a significant broadening and an
asymmetric deformation of the meson peak. We demonstrate that both in
vacuum and nuclear matter, the first two moments of the spectral function are
compatible with finite-energy QCD sum rules. A brief discussion of the
next-higher spectral moment involving strange four-quark condensates is also
presented.Comment: 7 pages, 5 figures; published versio
Can EU Conditionality Remedy Soft Budget Constraints in Transition Countries?
Soft budget constraints (SBCs) are a persistent feature of transition economies and have been blamed for i.a. a lack of fiscal consolidation and sluggish growth. EU eastward enlargement has - among other things - been conditioned on tackling SBCs. This paper analyzes such outside conditionality theoretically and empirically. First, modelling the SBC problem as a war of attrition between the applicant countries' governments and firms we find that outside conditionality can foster SBC hardening. Yet, toughening the EU stance or reducing the number of enlargement rounds may have ambiguous effects. Second, estimating SBC hardening in a partial adjustment model by measuring the reaction of employment to output changes we find that EU conditionality did indeed help candidates to fight SBCs.soft budget constraint, EU enlargement, war of attrition
Doorkeepers and Gatecrashers: EU Enlargement and Negotiation Strategies
This paper discusses the eastward enlargement process of the EU in the framework of a simple war of attrition bargaining game. Both players - the existing EU members and the applicants - benefit from enlargement, yet for the applicants reform to the acquis is costly, while the EU prefers substantially reformed candidates. A waiting game unfolds. Within this framework the present enlargement round is analyzed and policy results are deduced. For example, it is shown that delegating the evaluation of applicants to a third party, compensating applicants for their reform efforts or increasing the benefits for new members are all effective negotiation strategies for the EU that have been applied in the process.EU enlargement, eastern enlargement, bargaining, reform, war of attrition.
Disentangled Latent Speech Representation for Automatic Pathological Intelligibility Assessment
Speech intelligibility assessment plays an important role in the therapy of
patients suffering from pathological speech disorders. Automatic and objective
measures are desirable to assist therapists in their traditionally subjective
and labor-intensive assessments. In this work, we investigate a novel approach
for obtaining such a measure using the divergence in disentangled latent speech
representations of a parallel utterance pair, obtained from a healthy reference
and a pathological speaker. Experiments on an English database of Cerebral
Palsy patients, using all available utterances per speaker, show high and
significant correlation values (R = -0.9) with subjective intelligibility
measures, while having only minimal deviation (+-0.01) across four different
reference speaker pairs. We also demonstrate the robustness of the proposed
method (R = -0.89 deviating +-0.02 over 1000 iterations) by considering a
significantly smaller amount of utterances per speaker. Our results are among
the first to show that disentangled speech representations can be used for
automatic pathological speech intelligibility assessment, resulting in a
reference speaker pair invariant method, applicable in scenarios with only few
utterances available.Comment: Submitted to INTERSPEECH202
Molecular characterization of hematopoietic stem cells after in vitro amplification on biomimetic 3D PDMS cell culture scaffolds
Hematopoietic stem cell (HSC) transplantation is successfully applied since the late 1950s. However, its efficacy can be impaired by insufficient numbers of donor HSCs. A promising strategy to overcome this hurdle is the use of an advanced ex vivo culture system that supports the proliferation and, at the same time, maintains the pluripotency of HSCs. Therefore, we have developed artificial 3D bone marrow-like scaffolds made of polydimethylsiloxane (PDMS) that model the natural HSC niche in vitro. These 3D PDMS scaffolds in combination with an optimized HSC culture medium allow the amplification of high numbers of undifferentiated HSCs. After 14 days in vitro cell culture, we performed transcriptome and proteome analysis. Ingenuity pathway analysis indicated that the 3D PDMS cell culture scaffolds altered PI3K/AKT/mTOR pathways and activated SREBP, HIF1α and FOXO signaling, leading to metabolic adaptations, as judged by ELISA, Western blot and metabolic flux analysis. These molecular signaling pathways can promote the expansion of HSCs and are involved in the maintenance of their pluripotency. Thus, we have shown that the 3D PDMS scaffolds activate key molecular signaling pathways to amplify the numbers of undifferentiated HSCs ex vivo effectively
Phi meson spectral moments and QCD condensates in nuclear matter
A detailed analysis of the lowest two moments of the meson spectral function in vacuum and nuclear matter is performed. The consistency is examined between the constraints derived from finite energy QCD sum rules and the spectra computed within an improved vector dominance model, incorporating the coupling of kanonic degrees of freedom with the bare meson. In the vacuum, recent accurate measurements of the cross section allow us to determine the spectral function with high precision. In nuclear
matter, the modification of the spectral function can be described by the interactions of the kaons from \phi \rightarrow K\barK with the surrounding nuclear medium. This leads primarily to a strong broadening and an asymmetric deformation of the meson peak structure. We confirm that, both in vacuum and nuclear matter, the zeroth and first moments of the corresponding spectral functions satisfy the requirements of the finite energy sum rules to a remarkable degree of accuracy. Limits on the strangeness sigma term of the nucleon are examined in this context. Applying our results to the second moment of the spectrum, we furthermore discuss constraints on four-quark condensates and the validity of the commonly used ground state saturation approximation
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