6,463 research outputs found
On finite groups acting on acyclic low-dimensional manifolds
We consider finite groups which admit a faithful, smooth action on an acyclic
manifold of dimension three, four or five (e.g. euclidean space). Our first
main result states that a finite group acting on an acyclic 3- or 4-manifold is
isomorphic to a subgroup of the orthogonal group O(3) or O(4), respectively.
The analogue remains open in dimension five (where it is not true for arbitrary
continuous actions, however). We prove that the only finite nonabelian simple
groups admitting a smooth action on an acyclic 5-manifold are the alternating
groups A_5 and A_6, and deduce from this a short list of finite groups, closely
related to the finite subgroups of SO(5), which are the candidates for
orientation-preserving actions on acyclic 5-manifolds.Comment: 15 pages; improved versio
Holographic duals of 6d RG flows
A notable class of superconformal theories (SCFTs) in six dimensions is
parameterized by an integer , an ADE group , and two nilpotent elements
in . Nilpotent elements have a natural partial ordering,
which has been conjectured to coincide with the hierarchy of
renormalization-group flows among the SCFTs. In this paper we test this
conjecture for , where AdS duals exist in IIA. We work
with a seven-dimensional gauged supergravity, consisting of the gravity
multiplet and two non-Abelian vector multiplets. We show that
this theory has many supersymmetric AdS vacua, determined by two nilpotent
elements, which are naturally interpreted as IIA AdS solutions. The BPS
equations for domain walls connecting two such vacua can be solved
analytically, up to a Nahm equation with certain boundary conditions. The
latter admit a solution connecting two vacua if and only if the corresponding
nilpotent elements are related by the natural partial ordering, in agreement
with the field theory conjecture.Comment: 33 pages, 2 figure
Usefulness of Lead-In phase in determining risk/benefit of telaprevir treatment in patients with HCV cirrhosis
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Students' opinions on teaching and services provided by the Italian Universities: a proposal for a new evaluation scheme
In Italy, the evaluation of the internal effectiveness of academic training courses has been substantiated, for over 20 years, in periodical surveys on students' opinions on teaching and related services. The first proposal to homogenize the various measurement methods adopted by the Universities was advanced by the former National Committee for the Evaluation of the University System in 2000 and it was the reference model until 2011, when the first Board of Directors of the National Evaluation of University and Research Agency (ANVUR) took over. The Agency's attempt, within the AVA (Self-assessment, Periodic Evaluation and Accreditation) methodological framework, to enrich and update the survey highlighted a number of critical issues, essentially linked to the ways and times of participation of students, compared to the modalities in which the training offers of the universities are organized. Taking a cue from these critical issues, the purpose of this paper is to propose a new, simpler and more rational evaluation model, which still maintains substantial continuity with the inspiring principles of the past plants, and tries to consolidate the monitoring efforts made by the universities to date
Endogenous Royalty Factor in a Licensing Contract
The owner of a well known fashion brand grants a manufacturer the rights to produce and sell a second-line brand against a percentage of the sales called royalty. To this end, the brand owner and the manufacturer sign a licensing contract which assigns the owner, who has already determined his advertising campaign, the right of determining the royalty factor. The manufacturer will plan her advertising campaign for the licenced product in order to maximize her profit. The brand owner's objective is twofold: on one hand he wants to maximize the profit coming from the contract, on the other hand he wants to improve the value of the brand at the end of a given planning period. We model this interaction between the two agents using a Stackelberg game, where the brand owner is the leader and the manufacturer is the follower. We characterise the royalty percentage and the licensee's advertising effort which constitute the unique Stackelberg equilibrium of the game
Optimal advertising strategies in a sports licensing contract
We consider a licensing agreement that grants to a manufacturer (licensee) the rights to use the logo of a sports team (licensor) on the goods he produces. This contract stands over a royalty clause that re- quires that the licensee pays a financial reward to the licensor. A further payment can sometimes be required in terms of a sales percentage, in case the sales exceed a given amount. We take into account this partic- ular clause by considering a non-differentiable scrap value term in the objective functional of the licensee. We formulate and solve an optimal control problem, with non differentiable dependence on final state, in order to find the optimum advertising strategies for the licensee
New approaches to thyroid hormones and purinergic signaling
It is known that thyroid hormones influence a wide variety of events at the molecular, cellular, and functional levels. Thyroid hormones (TH) play pivotal roles in growth, cell proliferation, differentiation, apoptosis, development, and metabolic homeostasis via thyroid hormone receptors (TRs) by controlling the expression of TR target genes. Most of these effects result in pathological and physiological events and are already well described in the literature. Even so, many recent studies have been devoted to bringing new information on problems in controlling the synthesis and release of these hormones and to elucidating mechanisms of the action of these hormones unconventionally. The purinergic system was recently linked to thyroid diseases, including enzymes, receptors, and enzyme products related to neurotransmitter release, nociception, behavior, and other vascular systems. Thus, throughout this text we intend to relate the relationship between the TH in physiological and pathological situations with the purinergic signaling
Multifrequency JVLA observations of the X-shaped radio galaxy in Abell 3670
Context. X-shaped radio galaxies (XRGs) exhibit a pair of bright primary
lobes and a pair of weak secondary lobes (wings), which are oriented with an
angle that gives the structure a cross-like shape. Though several theoretical
models have been proposed to explain their origin, there is currently not a
general consensus on a formation scenario. Aims. We analysed new multifrequency
Karl G. Jansky Very Large Array (JVLA) radio data at 1.5, 5.5, 6, and 9 GHz of
the candidate XRG in Abell 3670 (A3670) in order to characterise and classify
it for the first time and to investigate its origin. Methods. We produced flux,
spectral index, and radiative age maps of A3670 by means of the new radio data.
We investigated the connection between the radio galaxy and its host, a
brightest cluster galaxy (BCG) with two optical nuclei classified as a dumbbell
galaxy. Finally we discussed the literature models and compared them to the
observed properties of A3670. Results. We classify A3670 as a Fanaroff-Riley
I-type XRG and measured a 1.4 GHz radio power of 1.7 x 10^25 W Hz-1. By
estimating the radiative age of the various source components, we find that the
wings are 20 Myr older than the lobes. We verified that the lobes and wings are
aligned with the major and minor axes of the optical galaxy, respectively, and
we estimated a black hole mass of 10^9 Msun , which is in agreement with the
typical properties of the XRGs. Conclusions. Among the discussed scenarios, the
jet-shell interaction model may best reproduce the observed properties of
A3670. The gas of a stellar shell is responsible for the deflection of the
jets, thus forming the wings. The presence of stellar shells in A3670 is
plausible, but it needs further optical observations to be confirmed.Comment: 11 pages, 19 figures grouped in 8, in press on Astronomy&Astrophysic
Tumor-associated and immunochemotherapy-dependent long-term alterations of the peripheral blood NK cell compartment in DLBCL patients
Natural Killer (NK) cells are a key component of tumor immunosurveillance and thus play an important role in rituximab-dependent killing of lymphoma cells via an antibody-dependent cellular cytotoxicity (ADCC) mechanism. We evaluated the phenotypic and functional assets of peripheral blood NK cell subsets in 32 newly-diagnosed diffuse large B-cell lymphoma (DLBCL) patients and in 27 healthy controls. We further monitored long-term modifications of patient NK cells for up to 12 months after rituximab-based immunochemotherapy. At diagnosis, patients showed a higher percentage of CD56dim and CD16C NK cells, and a higher frequency of GrzBC cells in CD56dim, CD56bright, and CD16C NK cell subsets than healthy controls. Conversely, DLBCL NK cell killing and interferon g (IFNg) production capability were comparable to those derived from healthy subjects. Notably, NK cells from refractory/relapsed patients exhibited a lower “natural” cytotoxicity. A marked and prolonged therapy-induced reduction of both “natural” and CD16- dependent NK cytotoxic activities was accompanied by the down-modulation of CD16 and NKG2D activating receptors, particularly in the CD56dim subset. However, reduced NK cell killing was not associated with defective lytic granule content or IFNg production capability. This study firstly describes tumor-associated and therapy-induced alterations of the systemic NK cell compartment in DLBCL patients. As these alterations may negatively impact rituximab-based therapy efficacy, our work may provide useful information for improving immunochemotherapeutic strategies
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