884 research outputs found
The Veneziano amplitude in AdSS from an 8-dimensional effective action
We study four-point functions of arbitrary half-BPS operators in a
4-dimensional SCFT with flavour group at genus-zero and
strong 't Hooft coupling, corresponding - via AdS/CFT - to the (
expansion of the) Veneziano amplitude on an AdSS background. We
adapt a procedure first proposed by Abl, Heslop and Lipstein in the context of
AdSS, and postulate the existence of an effective action in
terms of an -dimensional scalar field valued in the adjoint of the flavour
group. The various Kaluza-Klein correlators can then be computed by uplifting
the standard AdS/CFT prescription to the full product geometry with AdS
bulk-to-boundary propagators and Witten diagrams replaced by suitable AdSS versions. After elucidating the main features of the procedure,
valid at all orders in , we show explicit results up to order
. The results provide further evidence of a novel relation between
AdSS and flat amplitudes - which made its first appearance in
SYM - that is perhaps the most natural extension of the well
known flat-space limit proposed by Penedones to cases where AdS and S have the
same radius.Comment: 34 page
Performance Characteristics of Nano-Modified Asphalt Mixtures
The growing need for high quality paving materials has aroused an increasing interest in innovative reinforcing agents, such as those characterized by nanometric dimensions. The experimental study presented in this paper focused on the use in asphalt mixtures of nanoclays and multiwall carbon nanotubes as bitumen modifiers. The performance characteristics of asphalt mixtures containing these nano-sized additives and those of a reference neat mixture were compared in a wide array of temperature and loading conditions. The testing program included the assessment of linear viscoelastic characteristics, anti-rutting potential and crack propagation resistance, by means of stiffness modulus, flow number and semi-circular bending tests, respectively. Results highlighted that both types of nano-additives have the potential to improve the performance properties of neat asphalt mixtures, with nanoclays yielding a superior reinforcing actio
Interferometric length metrology for the dimensional control of ultra-stable Ring Laser Gyroscopes
We present the experimental test of a method for controlling the absolute
length of the diagonals of square ring laser gyroscopes. The purpose is to
actively stabilize the ring cavity geometry and to enhance the rotation sensor
stability in order to reach the requirements for the detection of the
relativistic Lense-Thirring effect with a ground-based array of optical
gyroscopes. The test apparatus consists of two optical cavities 1.32 m in
length, reproducing the features of the ring cavity diagonal resonators of
large frame He-Ne ring laser gyroscopes. The proposed measurement technique is
based on the use of a single diode laser, injection locked to a frequency
stabilized He-Ne/Iodine frequency standard, and a single electro-optic
modulator. The laser is modulated with a combination of three frequencies
allowing to lock the two cavities to the same resonance frequency and, at the
same time, to determine the cavity Free Spectral Range (FSR). We obtain a
stable lock of the two cavities to the same optical frequency reference,
providing a length stabilization at the level of 1 part in , and the
determination of the two FSRs with a relative precision of 0.2 ppm. This is
equivalent to an error of 500 nm on the absolute length difference between the
two cavities
BCJ relations in and the double-trace spectrum of super gluons
We revisit the four-point function of super gluons in in
the spirit of the large formalism and show how the integrand of a
generalised Mellin transform satisfies various non-trivial properties such as
decoupling identity, BCJ relations and colour-kinematic duality, in a
way that directly mirrors the analogous relations in flat space. We unmix the
spectrum of double-trace operators at large and find all anomalous
dimensions at leading order. The anomalous dimensions follow a very simple
pattern, resembling those of other theories with hidden conformal symmetries.Comment: 9 page
Dai patti di retrocessione a prezzo garantito alle azioni "redimibili" (una rilettura del divieto del patto leonino nella s.p.a. riformata)
Il contributo affronta la delicata problematica della liceitĂ di clausole statutarie che riproducano il contenuto dei patti parasociali di retrocessione a prezzo garantito. Per effetto di tali clausole, i finanziatori di iniziative di venture capital potrebbero beneficiare della tutela reale in caso di inadempimento degli obblighi assunti dalla societĂ e/o dal suo socio di maggioranza che hanno ottenuto il finanziamento partecipativo
Effects of Exercise on the Airways
In the last ten years, the effects of exercise on bronchial epithelial cells and inflammatory
cells in the airways have been studied in detail, and such new information has been
combined with previous knowledge on bronchial reactivity and asthma evoked by exercise
in asthmatic patients and athletes. The resulting picture is very complex, and the potential
clinical consequences are often contradictory, suggesting the opportunity to define different
phenotypes of exercise-associated airway changes (Lee & Anderson, 1985; Haahtela et al.,
2008; Moreira et al., 2011a).
Studies in asthmatic athletes in the 90\u2019 had began to explore the possibility that airway
inflammation might be involved in exercise-associated respiratory symptoms. However,
studies in non-asthmatic athletes also found increased number of inflammatory cells not
only at rest, but also after strenuous endurance exercise (Bonsignore et al., 2001). It was
therefore hypothesized that endurance exercise may physiologically cause influx of
inflammatory cells into the airways, associated with low or absent inflammatory activation
(Bonsignore et al., 2003a). Subsequent studies in athletes and animal models have extended
these finding, but the mechanisms of inflammatory cell recruitment into the airways and the
tight control of inflammatory activation physiologically associated with exercise remain
poorly understood.
Exercise is a known cause of bronchoconstriction in asthmatic patients (Cabral et al., 1999)
and athletes (Parsons & Mastronarde, 2005). A large number of asthmatic elite athletes
participate to international top-level competitions, and guidelines regarding management of
asthmatic athletes (Fitch et al., 2008) and rules on the use of anti-asthmatic drugs have been
issued (World Anti-Doping Agency, WADA, Oct. 18 2010 report). However, exercise is a
powerful physiologic stimulus for bronchodilatation, and some reports underlined that
exercise training may actually downmodulate bronchial reactivity in normal subjects
(Scichilone et al., 2005, 2010), asthmatic children (Bonsignore et al., 2008) and animal models
of asthma (Hewitt et al., 2010).
This chapter will summarize the changes induced by acute exercise and training in
bronchial reactivity and airway cells in both humans and animal models. It will also discuss
the changing paradigm regarding the impact of physical activity in patients with bronchial
asthma, and the new perspectives of exercise-based rehabilitation in patients with
respiratory diseases such as chronic obstructive pulmonary disease (COPD)
LCA of hospital solid waste treatment alternatives in a developing country: The case of District Swat, Pakistan
Improper management of hospital waste leads to serious health and environmental issues, particularly in the case of developing countries, where, often, applied technologies are obsolete and there is a lack of compliance with respect to international best practices. The present study is designed to assess the environmental impacts of hospital waste management practices in Swath District, Pakistan. For this purpose, a life-cycle assessment (LCA) is applied for the estimation of different impacts of current and alternative hospital solid waste (HSW) treatment practices. Two scenarios are used to describe the current alternative practices (Scenario A and Scenario B), referring either to incineration or to direct landfilling of HSW without any sorting of collected materials. Conversely, Scenario C, which includes the use of pyrolysis and chemical disinfection, are considered as an up-to-date alternative, based on current international recommendations in this field. Prior to the analysis of impacts, due to the lack of available information, data were directly collected from both government and private hospitals in District Swat, involving measurements and a characterization of collected waste. In parallel, interviews were conducted, involving the hospitals' personnel. With respect to waste generation, government hospitals produce a larger amount of waste (74%) compared to private hospitals (24%). Poor regulatory indications and the absence of clear obligations for collection, disposal and management still represent a first obstacle to implement good practices. After defining the boundary of the system and the functional unit, according to standardized LCA practices, a life-cycle impact assessment (LCIA) was conducted, considering eight impact categories: human toxicity, freshwater eco-toxicity, marine aquatic eco-toxicity, terrestrial eco-toxicity, acidification potential, climate change, eutrophication and photochemical oxidation. The current practices (Scenario A and Scenario B) turned out to be the worst for all categories. In particular, the largest impact of all is recorded for human toxicity generated by incineration. In parallel, it must be considered that, currently, no recycling or reusing practices are implemented. Conversely, Scenario C (alternative up-to-date practices) would generate lower impacts. In detail, the highest value was recorded for marine aquatic ecotoxicity in relation to pyrolysis. Applying Scenario C, it would be possible to recover some materials, such as plastics, paper and sharps. In detail, considering the observed compositional characteristics, it would be possible to recover up to 78% of sharps and recycle 41% of plastic and paper from the general waste stream. Moreover, energy could be recovered from the pyrolysis process, generating a further benefit for the surrounding area. A lack of awareness, knowledge and infrastructures prevents the application of correct management practices, further degrading life and environmental conditions of this remote region of Pakistan. The huge difference in impacts between current practices and alternatives is demonstrated, showing a clear alternative for future management plans in this remote region and supporting future actions for local policymakers and hospital managers
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