2,009 research outputs found
Moduli Stabilisation with Nilpotent Goldstino: Vacuum Structure and SUSY Breaking
We study the effective field theory of KKLT and LVS moduli stabilisation
scenarios coupled to an anti-D3-brane at the tip of a warped throat. We
describe the presence of the anti-brane in terms of a nilpotent goldstino
superfield in a supersymmetric effective field theory. The introduction of this
superfield produces a term that can lead to a de Sitter minimum. We fix the
Kaehler moduli dependence of the nilpotent field couplings by matching this
term with the anti-D3-brane uplifting contribution. The main result of this
paper is the computation, within this EFT, of the soft supersymmetry breaking
terms in both KKLT and LVS for matter living on D3-brane (leaving the D7-brane
analysis to an appendix). A handful of distinct phenomenological scenarios
emerge that could have low energy implications, most of them having a split
spectrum of soft masses. Some cosmological and phenomenological properties of
these models are discussed. We also check that the attraction between the
D3-brane and the anti-D3-brane does not affect the leading contribution to the
soft masses and does not destabilise the system.Comment: 26+14 pages, 1 figure; references and clarifications added, typos
fixe
On the inconsistency of the Malmquist-Luenberger index
Apart from the well-known weaknesses of the standard Malmquist productivity index
related to infeasibility and not accounting for slacks, already addressed in the literature,
we identify a new and significant drawback of the Malmquist-Luenberger index
decomposition that questions its validity as an empirical tool for environmental
productivity measurement associated with the production of bad outputs. In particular,
we show that the usual interpretation of the technical change component in terms of
production frontier shifts can be inconsistent with its numerical value, thereby resulting
in an erroneous interpretation of this component that passes on to the index itself. We
illustrate this issue with a simple numerical example. Finally, we propose a solution for
this inconsistency issue based on incorporating a new postulate for the technology
related to the production of bad output
The Directional Profit Efficiency Measure: On Why Profit Inefficiency is either Technical or Allocative
The directional distance function has been introduced in the efficiency literature with the intention of relaxing the fixed orientations represented by its classical input and output counterparts. However, the criteria underlying the choice of its associated directional vector are numerous. When market prices are observed and firms have a profit maximizing behavior, it seems natural to choose as directional vector that projecting inefficient firms towards profit maximizing benchmarks. Based on that choice of directional vector, we introduce the profit efficiency measure and show that, in this general setting, profit inefficiency can be categorized as either technical -for firms situating in the interior of the technology- or allocative -for firms lying on the frontier. We implement and illustrate the analytical model by way of Data Envelopment Analysis techniques, where the profit maximizing benchmark may not be unique, and introduce the necessary optimizing program for profit inefficiency measurement.Directional Distance Function; Profit Efficiency; Technical Efficiency; Allocative Efficiency; Data Envelopment Analysis.
Acetti, Chiara, Leuzzi, Daniela, Pagani, Lara, Eroi nell’Iliade. Personaggi e strutture narrative. A cura de L. Pagani, Roma, Edizioni di Storia e Letteratura, 2008, XIII + 496 pp.
BIM: a technology acceptance model in Peru
The purpose of this paper is to empirically study factors that facilitate the adoption of building information modelling (BIM) among practitioners using the unified theory of technology acceptance model (TAM). The factors identified in the TAM were examined using a quantitative approach. The empirical investigation has been conducted using a survey questionnaire. The data set has been obtained from 73 architects and engineers in Peru. Results show that Perceived Usefulness (PU) is the most important determinant of Behavioural Intention (BI), while Perceived Ease of Use (PEOU) is found to have no significant effect on BI. The findings provide an excellent backdrop in the development of policy and a roadmap for BIM implementation in Peru. The original contribution and value of the paper is the use of TAM to provide empirical evidence on factors that facilitate BIM adoption in Peru
Sequestered de Sitter String Scenarios: Soft-terms
We analyse soft supersymmetry breaking in type IIB de Sitter string vacua
after moduli stabilisation, focussing on models in which the Standard Model is
sequestered from the supersymmetry breaking sources and the spectrum of
soft-terms is hierarchically smaller than the gravitino mass . Due to
this feature, these models are compatible with gauge coupling unification and
TeV scale supersymmetry with no cosmological moduli problem. We determine the
influence on soft-terms of concrete realisations of de Sitter vacua constructed
from supersymmetric effective actions. One of these scenarios provides the
first study of soft-terms for consistent string models embedded in a compact
Calabi-Yau manifold with all moduli stabilised. Depending on the moduli
dependence of the Kaehler metric for matter fields and on the mechanism
responsible to obtain a de Sitter vacuum, we find two scenarios for
phenomenology: (i) a split-supersymmetry scenario where gaugino masses are
suppressed with respect to scalar masses: for ; (ii) a typical MSSM scenario where all soft-terms are of the same
order: . Background fluxes
determine the numerical coefficients of the soft-terms allowing for small
variations of parameters as is necessary to confront data and to interpolate
between different scenarios. We comment on different stringy origins of the
mu-term and potential sources of desequestering.Comment: 27 pages + appendices, 2 figure
Sunitinib-induced asthenia: from molecular basis to clinical relief
[Abstract] Asthenia-fatigue syndrome (AFS) is defined as a persistent, subjective sense of tiredness related to cancer or its treatment and greatly impacts quality of life among cancer patients. All tyrosine kinase inhibitors, but especially sunitinib, may induce AFS. The reason for sunitinib-induced AFS is not yet well understood. Adverse events caused by sunitinib associated with AFS may include anemia, hypothyroidism, nausea and vomiting. However, AFS is also reported when active treatment with sunitinib is ongoing, and no other relevant adverse event can justify it. The molecular mechanisms by which sunitinib triggers AFS remain elusive. Sunitinib displays multiple off-target tyrosine-kinase interactions and competitively inhibits multiple proteins through the blockade of their ATP-binding sites. The broad spectrum of kinases inhibited may play a key role not only in terms of activity but also in terms of toxicity induced by sunitinib. This study considered different clinical observations and current metabolic and pharmacological knowledge, leading to hypotheses regarding which molecular mechanisms may be involved in sunitinib-induced AFS in cancer patients. Deeper knowledge of the molecular mode of action of sunitinib may lead to improved optimization of its clinical use
- …