Conformal Dynamics of 0-Branes

We investigate the dynamics of dilatonic D-dimensional 0-branes in the near-horizon regime. The theory is given in a twofold form: two-dimensional dilaton gravity and nonlinear sigma model. Using asymptotic symmetries, duality relations, and sigma model techniques we find that the theory has three conformal points which correspond to (a) the asymptotic (Anti-de Sitter) region of the two-dimensional spacetime, (b) the horizon of the black hole, and (c) the infinite limit of the coupling parameter. We show that the conformal symmetry is perturbatively preserved at one-loop, identify the corresponding conformal field theories, and calculate the associated central charges. Finally, we use the conformal field theories to explain the thermodynamical properties of the two-dimensional black holes.Comment: 22 pages, LaTex fil

Evidence for uteroplacental malperfusion in fetuses with major congenital heart defects.

AIMS: Fetuses affected by congenital heart defects (CHD) are considered to be at increased risk of fetal growth restriction and intrauterine demise. Whether these risks are a direct consequence of fetal CHD or a result of associated uteroplacental dysfunction is not evident from the data of recent studies. The aim of this study was to investigate the prevalence of uteroplacental dysfunction reflected by abnormal uterine artery Doppler indices and reduced fetal growth in CHD pregnancies. METHODS: This is a retrospective case-control study including singleton pregnancies referred for detailed fetal cardiac assessment subsequently diagnosed with or without CHD. Mid-trimester uterine artery Doppler assessment at 20-24 weeks as well as third trimester fetal biometry and arterial Doppler pulsatility indices (PI) were performed. All fetal biometry were converted into centiles and Doppler values to multiples of median (MoM) to adjust for physiological changes with gestation. RESULTS: The study included 811 pregnancies including 153 cases where the fetus was diagnosed with CHD. Mid-pregnancy uterine artery PI was significantly higher in women with fetal CHD compared to controls (0.90MoM vs 0.83MoM; p = 0.006). In the third trimester, median centiles for fetal head circumference (45.4 vs 57.07; p<0.001), abdominal circumference (51.17 vs 55.71; p = 0.014), estimated fetal weight (33.6 vs 56.7; p<0.001) and cerebroplacental ratio (CPR: 0.84MoM vs 0.95MoM; p<0.001) were significantly lower in fetuses with CHD compared to controls. The percentage of small for gestational age births <10th centile (24.0% vs 10.7%; <0.001) and low CPR <0.6MoM (11.7% vs 2.5%; p<0.001) were significantly higher in the fetal CHD cohort. CONCLUSIONS: Mid-pregnancy uterine artery resistance is increased and subsequent fetal biometry reduced in pregnancies with CHD fetuses. These findings suggest that fetal CHD are associated with uteroplacental dysfunction, secondary to impaired maternal uteroplacental perfusion resulting in relative fetal hypoxaemia and reduced fetal growth

Un insediamento di età eneolitica nella Sardegna centro-occidentale: il villaggio di cultura Monte Claro nel sito di Cuccurada, Mogoro (OR)

Nel sito archeologico di Cuccurada, in comune di Mogoro, è stato posto in luce, a partire dagli anni ’90 del secolo scorso, un vasto insediamento pluristratificato che ha restituito varie fasi di occupazione preistorica e protostorica dal Neolitico Recente (cultura di Ozieri), passando dall’Eneolitico (cultura di Monte Claro) sino alle Età del Bronzo e del Ferro, con momenti di rioccupazione più tarda di epoca romana e medievale. In questo lavoro si espone in dettaglio la fase insediativa di età eneolitica, a cui sono riferibili resti monumentali e manufatti pertinenti alla cultura di Monte Claro. Si presentano inediti dati stratigrafici, materiali ceramici e spunti di analisi sulla cultura Monte Claro in questa zona della Sardegna centro-occidentale.In the archaeological site of Cuccurada, in municipality of Mogoro, the research has revealed, since the 90s of the last century, a large pluristratified settlement. Various phases of prehistoric and protohistoric occupation have been recognized, from recent Neolithic (Ozieri culture), with evidences ofCopper Age (Monte Claro culture), up to the Bronze Age and Iron Age; the site was later reoccupied in Roman and medieval age. In this work we expose in detail the settlement phase of the Copper Age, to which monumental remains and artifacts pertinent to the Monte Claro culture are referable. We present unpublished stratigraphical data, ceramic materials and new elements ofanalysis about the cultural phase ofMonte Claro in this zone ofcentral-western Sardinia

Aerobic environment ensures viability and anti-oxidant capacity when seeds are wet with negative effect when moist: implications for persistence in the soil

Interchangeable effects of temperature, moisture content and oxygen on seed longevity have been mostly examined to estimate seed viability during long-term dry storage, whereas few experiments have studied seed viability under near-natural conditions to evaluate seed persistence in the soil. To this end, we artificially aged seeds of Ranunculus baudotii, a hydrophyte widely distributed in temporary ponds constituting an abundant soil seed bank. Seeds were exposed to controlled ageing at three different relative humidities (RH) under both aerobic and anoxic conditions. Their viability, water content, membrane damage, oxidative stress and anti-oxidant enzymatic defence activity were evaluated. Seed survival was longer at higher relative humidity (97% RH), and lowest at a relative humidity (90% RH) simulating moist but not waterlogged soils. Anoxic conditions showed a protective role on viability at lower moisture contents (70% RH). Seed viability was negatively associated with hydrogen peroxide content and correlated with anti-oxidant enzyme activities, but not with membrane damage. Altogether, these results suggest negative roles for moist soils and anoxia in determining seed persistence in the field, but at higher moisture contents the negative effects of anaerobia diminished. The anti-oxidant system activation, even under unfavourable conditions, might recover seeds once all protective processes can operate, pointing out the plasticity of mechanisms involved in seed loss viability

Heat Transfer Analysis of Damaged Shrouded High-Pressure Turbine Rotor Blades

Due to the increasingly high turbine inlet temperatures, heat transfer analysis is now, more than ever, a vital part of the design and optimization of high-pressure turbine rotor blades of a modern jet engine. The present study aimed to find out how shape deviation and in-service deterioration affect heat exchange patterns on the rotor blade. The rotor geometries used for this analysis are represented by a set of high-resolution 3D structured light scans of blades with the same number of in-service hours. An automatic meshing technique was employed to generate high-resolution meshes directly on the scanned rotor geometries, which captured all the surface features with high fidelity. Steady-state 3D RANS flow simulations with a k-ω SST turbulence model were conducted on a one-and-a-half stage computational domain of the scanned geometries. First, the distribution of the heat transfer coefficient was calculated for each blade; then, a correlation was sought between the heat transfer coefficient and parametrized shape deviation, to assess the impact of each parameter on HTC levels

Neural tracking of phrases in spoken language comprehension is automatic and task-dependent

Linguistic phrases are tracked in sentences even though there is no one-to-one acoustic phrase marker in the physical signal. This phenomenon suggests an automatic tracking of abstract linguistic structure that is endogenously generated by the brain. However, all studies investigating linguistic tracking compare conditions where either relevant information at linguistic timescales is available, or where this information is absent altogether (e.g., sentences versus word lists during passive listening). It is therefore unclear whether tracking at phrasal timescales is related to the content of language, or rather, results as a consequence of attending to the timescales that happen to match behaviourally relevant information. To investigate this question, we presented participants with sentences and word lists while recording their brain activity with magnetoencephalography (MEG). Participants performed passive, syllable, word, and word-combination tasks corresponding to attending to four different rates: one they would naturally attend to, syllable-rates, word-rates, and phrasal-rates, respectively. We replicated overall findings of stronger phrasal-rate tracking measured with mutual information for sentences compared to word lists across the classical language network. However, in the inferior frontal gyrus (IFG) we found a task effect suggesting stronger phrasal-rate tracking during the word-combination task independent of the presence of linguistic structure, as well as stronger delta-band connectivity during this task. These results suggest that extracting linguistic information at phrasal rates occurs automatically with or without the presence of an additional task, but also that IFG might be important for temporal integration across various perceptual domains

Elastic Chiral Waveguides with Gyro-Hinges

This article presents a novel chiral structure, consisting of Euler–Bernoulli beams connected to gyroscopic spinners.Anew type of boundary condition is introduced, which is referred to as a gyrohinge. In this system, flexural waves are coupled with rotational motion.Time-harmonic conditions are derived by assuming small nutation angles of the spinners. It is shown that the eigenfrequencies of a finite beam with gyro-hinges at one or both ends change dramatically with the moments of inertia and the spin and precession rates of the spinners. The formulation is then extended to elastic beams with periodically-spaced gyro-hinges, whose dispersion properties are investigated in detail. In particular, it is shown how stop-bands and standing modes are affected by the introduction of gyroscopic spinners at the junctions. It is also demonstrated that a periodic system composed of beams connected by gyro-hinges represents a good approximation of a gyrobeam, a theoretical structural element consisting of an elastic beam possessing a continuous distribution of stored angular momentum. The gyricity coefficient of a gyrobeam is then interpreted in terms of the physical parameters of the system of beams with gyroscopic spinners. This article opens a new perspective on the design and practical implementation of chiral mechanical systems

THE VERNACULAR HERITAGE OF GJIROKASTRA (ALBANIA): ANALYSIS OF URBAN AND CONSTRUCTIVE FEATURES, THREATS AND CONSERVATION STRATEGIES

Abstract. The old town of Gjirokastra (Albania), was included in the World Heritage List in 2005 thanks to the valuable presence of several remarkable examples of Ottoman-styled houses and in the integrity of the vernacular urban landscape. The urban structure is strongly influenced by the orography of the Drino valley and its slopes where the city was founded. Stone is the building material that characterizes the paving of the streets, the walls of the buildings and the roof coverings. The wood, mostly local, was used to build the frame structure of the upper floors and the roofs, in order to provide large windows and bright interior spaces. In December 2018, as part of the activities of the 3D Past project, founded by Eu Creative Europe Programme, Italian and Albanian students took part in a workshop in Gjirokastra. Such an initiative was designed to understand the tangible and intangible components of the vernacular heritage of Gjrokastra. In a multidisciplinary approach, students, professors, researchers and local experts analysed the morphological features of the historic center, the public spaces, and the traditional building systems. Traditional instruments such as the direct survey, the on-site observation and the interviews were adopted in combination with more innovative tools such as the laser scanner and the photogrammetry. This contribution not only illustrates the results of a multi-scale analysis, but it also highlights the transformations and threats that endanger the transmission of the unique characteristics of the city to the future generations. Moreover, it deals with the conservation strategies currently in use and some possible future measures that can contribute to the sustainable safeguard and development of the site