Modeling Stable Matching Problems with Answer Set Programming

The Stable Marriage Problem (SMP) is a well-known matching problem first introduced and solved by Gale and Shapley (1962). Several variants and extensions to this problem have since been investigated to cover a wider set of applications. Each time a new variant is considered, however, a new algorithm needs to be developed and implemented. As an alternative, in this paper we propose an encoding of the SMP using Answer Set Programming (ASP). Our encoding can easily be extended and adapted to the needs of specific applications. As an illustration we show how stable matchings can be found when individuals may designate unacceptable partners and ties between preferences are allowed. Subsequently, we show how our ASP based encoding naturally allows us to select specific stable matchings which are optimal according to a given criterion. Each time, we can rely on generic and efficient off-the-shelf answer set solvers to find (optimal) stable matchings.Comment: 26 page

Azimuthal Asymmetry of Direct Photons in High Energy Nuclear Collisions

We show that a sizeable azimuthal asymmetry, characterized by a coefficient v_2, is to be expected for direct photons produced in non-central high energy nuclear collisions. This signal is generated by photons radiated by jets interacting with the surrounding hot plasma. The anisotropy is out of phase by an angle $\pi/2$ with respect to that associated with the elliptic anisotropy of hadrons, leading to negative values of v_2. Such an asymmetry, if observed, could be a signature for the presence of a quark gluon plasma and would establish the importance of jet-plasma interactions as a source of electromagnetic radiation.Comment: New title. Final versio

Drug-induced stress granule formation protects sensory hair cells in mouse cochlear explants during ototoxicity

Stress granules regulate RNA translation during cellular stress, a mechanism that is generally presumed to be protective, since stress granule dysregulation caused by mutation or ageing is associated with neurodegenerative disease. Here, we investigate whether pharmacological manipulation of the stress granule pathway in the auditory organ, the cochlea, affects the survival of sensory hair cells during aminoglycoside ototoxicity, a common cause of acquired hearing loss. We show that hydroxamate (-)-9, a silvestrol analogue that inhibits eIF4A, induces stress granule formation in both an auditory cell line and ex-vivo cochlear cultures and that it prevents ototoxin-induced hair-cell death. In contrast, preventing stress granule formation using the small molecule inhibitor ISRIB increases hair-cell death. Furthermore, we provide the first evidence of stress granule formation in mammalian hair cells in-vivo triggered by aminoglycoside treatment. Our results demonstrate that pharmacological induction of stress granules enhances cell survival in native-tissue, in a clinically-relevant context. This establishes stress granules as a viable therapeutic target not only for hearing loss but also other neurodegenerative diseases.EI:595 - Action on Hearing Loss; 091092/Z/09/Z - Wellcome Trust (Wellcome); MR/N004329/1 - RCUK | Medical Research Council (MRC)Published versio

Low mass dimuons within a hybrid approach

We analyse dilepton emission from hot and dense hadronic matter using a hybrid approach based on the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) transport model with an intermediate hydrodynamic stage for the description of heavy-ion collisions at relativistic energies. Focusing on the enhancement with respect to the contribution from long-lived hadron decays after freeze-out observed at the SPS in the low mass region of the dilepton spectra (often referred to as "the excess"), the relative importance of the emission from the equilibrium and the non-equilibrium stages is discussed.Comment: Proceedings of Hot Quarks 2010, 21-26 June 2010 Las Londe Les Maures; v2: Corrected typos and added a commen

Dilepton Production in Nucleon-Nucleon Reactions With and Without Hadronic Inelasticities

We calculate elementary proton-proton and neutron-proton bremsstrahlung and their contribution to the $e^+e^-$ invariant mass distribution. At 4.9 GeV, the proton-proton contribution is larger than neutron-proton, but it is small compared to recent data. We then make a first calculation of bremsstrahlung in nucleon-nucleon reactions with multi-hadron final states. Again at 4.9 GeV, the many-body bremsstrahlung is larger than simple nucleon-nucleon bremsstrahlung by more than an order of magnitude in the low-mass region. When the bremsstrahlung contributions are summed with Dalitz decay of the $\eta$, radiative decay of the $\Delta$ and from two-pion annihilation, the result matches recent high statistics proton-proton data from the Dilepton Spectrometer collaboration.Comment: 1+17 pages plus 11 PostScript figures uuencoded and appended, McGill/93-9, TPI-MINN-93/18-

Elliptic flow of thermal photons and dileptons

In this talk we describe the recently discovered rich phenomenology of elliptic flow of electromagnetic probes of the hot matter created in relativistic heavy-ion collisions. Using a hydrodynamic model for the space-time dynamics of the collision fireball created in Au+Au collisions at RHIC, we compute the transverse momentum spectra and elliptic flow of thermal photons and dileptons. These observables are shown to provide differential windows into various stages of the fireball expansion.Comment: 8 pages, including 9 figures. Invited talk at the Hard Probes 2006 Conference (Asilomar, June 9-16, 2006), to appear in the Proceedings (Elsevier

Does the quark cluster model predict any isospin two dibaryon resonance?

We analyze the possible existence of a resonance in the $J^P=0^-$ channel with isospin two by means of nucleon-$\Delta$ interactions based on the constituent quark model. We solve the bound state and the scattering problem using two different potentials, a local and a non-local one. The non-local potential results to be the more attractive, although not enough to generate the experimentally predicted resonance.Comment: 9 pages in Latex (revtex), 2 eps figures available under reques

Differential function and maturation of human stem cell-derived islets after transplantation

Insulin-producing stem cell-derived islets (SC-islets) provide a virtually unlimited cell source for diabetes cell replacement therapy. While SC-islets are less functional when first differentiated in vitro compared to isolated cadaveric islets, transplantation into mice has been shown to increase their maturation. To understand the effects of transplantation on maturation and function of SC-islets, we examined the effects of cell dose, transplantation strategy, and diabetic state in immunocompromised mice. Transplantation of 2 and 5, but not 0.75 million SC-islet cells underneath the kidney capsule successfully reversed diabetes in mice with pre-existing diabetes. SQ and intramuscular injections failed to reverse diabetes at all doses and had undetectable expression of maturation markers, such as MAFA and FAM159B. Furthermore, SC-islets had similar function and maturation marker expression regardless of diabetic state. Our results illustrate that transplantation parameters are linked to SC-islet function and maturation, providing ideal mouse models for preclinical diabetes SC therapy research

Two-loop Compton and annihilation processes in thermal QCD

We calculate the Compton and annihilation production of a soft static lepton pair in a quark-gluon plasma in the two-loop approximation. We work in the context of the effective perturbative expansion based on the resummation of hard thermal loops. Double counting is avoided by subtracting appropriate counterterms. It is found that the two-loop diagrams give contributions of the same order as the one-loop diagram. Furthermore, these contributions are necessary to obtain agreement with the naive perturbative expansion in the limit of vanishing thermal masses.Comment: Latex, 24 pages, postscript figures included with the package graphic