An efficient representation for kernels in the 2d dynamics displacement discontinuity method for cracked elastic materials

The displacement discontinuity method is a rather standard approach to study cracks in elastic materials. This is in fact a certain technique to construct the system of Boundary Integral Equations (BIE), or equivalently, Boundary Element Methods (BEM). In the static case this typically results in explicit expressions for the kernels of respective BIE, both in 2d and 3d problems. In the work the authors give efficient representations for such kernels in explicit form

Reconstruction of Crack Cluster in the Rectangular Domain by Ultrasonic Waves

In the present article we study the reconstruction problem for clusters of linear cracks inside a rectangular domain. The parameters to be reconstructed are the number of cracks and the size and slope of each defect. The scanning is performed by a single ultrasonic transducer placed at a certain boundary point. The input data, used for the reconstruction algorithm, is taken as measured oscillation amplitudes over an array of chosen boundary points. The proposed numerical algorithm is tested on some examples with multiple clusters of cracks whose position and geometry are known a priori

Higher Derivative Corrections to Locally Black Brane Metrics

In this paper we generalize the construction of locally boosted black brane space time to higher derivative gravities. We consider the Gauss-Bonnet term (with coefficient $\alpha'$) as a toy example. We find the solution to the $\alpha'$ corrected Einstein equations to first order in the boundary derivative expansion. This allows us to find the $\alpha'$ corrections to the boundary stress tensor in the presence of the Gauss-Bonnet term in the bulk action. We therefore obtain the ratio of shear viscosity to entropy which agrees with other methods of computation in the literature.Comment: 0+17 page

Central Executive Dysfunction and Deferred Prefrontal Processing in Veterans with Gulf War Illness.

Gulf War Illness is associated with toxic exposure to cholinergic disruptive chemicals. The cholinergic system has been shown to mediate the central executive of working memory (WM). The current work proposes that impairment of the cholinergic system in Gulf War Illness patients (GWIPs) leads to behavioral and neural deficits of the central executive of WM. A large sample of GWIPs and matched controls (MCs) underwent functional magnetic resonance imaging during a varied-load working memory task. Compared to MCs, GWIPs showed a greater decline in performance as WM-demand increased. Functional imaging suggested that GWIPs evinced separate processing strategies, deferring prefrontal cortex activity from encoding to retrieval for high demand conditions. Greater activity during high-demand encoding predicted greater WM performance. Behavioral data suggest that WM executive strategies are impaired in GWIPs. Functional data further support this hypothesis and suggest that GWIPs utilize less effective strategies during high-demand WM

Multiple algebraisations of an elliptic Calogero-Sutherland model

Recently, Gomez-Ullate et al. (1) have studied a particular N-particle quantum problem with an elliptic function potential supplemented by an external field. They have shown that the Hamiltonian operator preserves a finite dimensional space of functions and as such is quasi exactly solvable (QES). In this paper we show that other types of invariant function spaces exist, which are in close relation to the algebraic properties of the elliptic functions. Accordingly, series of new algebraic eigenfunctions can be constructed.Comment: 9 Revtex pages, 3 PS-figures; Summary, abstract and conclusions extende

On multiple crack identification by ultrasonic scanning

The present work develops an approach which reduces operator equations arising in the engineering problems to the problem of minimizing the discrepancy functional. For this minimization, an algorithm of random global search is proposed, which is allied to some genetic algorithms. The efficiency of the method is demonstrated by the solving problem of simultaneous identification of several linear cracks forming an array in an elastic medium by using the circular Ultrasonic scanning

the tempio della consolazione in todi integrated geomatictechniques for a monument description including structuraldamage evolution in time

The Tempio della Consolazione in Todi (16th cent.) has always been one of the most significant symbols of the Umbrian landscape. Since the first times after its completion (1606) the structure has exhibited evidences of instability, due to foundation subsiding and/or seismic activity. Structural and geotechnical countermeasures have been undertaken on the Tempio and its surroundings from the 17th century until recent times. Until now a truly satisfactory analysis of the overall deformation and attitude of the building has not been performed, since the existing surveys record the overhangs of the pillars, the crack pattern or the subsidence over limited time spans. Describing the attitude of the whole church is in fact a complex operation due to the architectural character of the building, consisting of four apses (three polygonal and one semicircular) covered with half domes, which surround the central area with the large dome. The present research aims to fill the gap of knowledge with a global study based on geomatic techniques for an accurate 3D reconstruction of geometry and attitude, integrated with a historical research on damage and interventions and a geotechnical analysis. The geomatic survey results from the integration of different techniques: GPS-GNSS for global georeferencing, laser scanning and digital photogrammetry for an accurate 3D reconstruction, high precision total station and geometric leveling for a direct survey of deformations and cracks, and for the alignment of the laser scans. The above analysis allowed to assess the dynamics of the cracks occurred in the last 25 years by a comparison with a previous survey. From the photographic colour associated to the point cloud was also possible to map the damp patches showing on the domes intrados, mapping their evolution over the last years

Kidney transplantation in patients with previous renal cancer : a critical appraisal of current evidence and guidelines

Due to the increasing occurrence of renal cell carcinoma (RCC) in the general population and the high prevalence of chronic kidney disease among cancer patients, many people with a previous RCC may eventually require renal replacement therapy including kidney transplantation. They should accordingly be evaluated to assess their life expectancy and the risk that the chronic immunosuppressive therapy needed after grafting might impair their long-term outcome. Current guidelines on listing patients for renal transplantation suggest that no delay is required for subjects with small or incidentally discovered RCC, while the recommendations for patients who have been treated for a symptomatic RCC or for those with large or invasive tumours are conflicting. The controversial results reported by even recent studies focusing on the cancer risk in kidney graft recipients with a prior history of malignancy do not help to clarify the doubts arising in everyday clinical practice. Several tools, including integrated scoring systems, are currently available to assess the prognosis of patients with a previous RCC and, although they have not been validated in subjects receiving long-term immunosuppressive drugs, they can be used to identify patients suitable to be listed for grafting. Among these, the Leibovich score is currently the most widely used as it has proved simple and reliable enough and helps categorize renal transplant candidates. According to this system, subjects with a score from 0 to 2 are at low risk and may be listed without delay, while those with a score of 6 or higher should be excluded from grafting. In addition, other factors have an established positive prognostic value, including chromophobe or clear cell papillary tumour, or G1 grade cancer; on the contrary, medullary or Bellini\u2019s duct carcinoma or those with sarcomatoid dedifferentiation at histological examination should be excluded. All other patients would be better submitted to careful individual evaluation by an Oncologist before being listed for renal transplantation, pending studies specifically focusing on cancer risk evaluation in people already treated for malignancy receiving long-term immunosuppressive therapy

FRCM retrofitting techniques for masonry walls: a literature review and some laboratory tests

The experimental characterisation of externally bonded composite materials as strengthening solutions for masonry structures, such as basalt textile reinforced mortar (BTRM) or fiber reinforced concrete (FRC), has been receiving increasing attention due to their outstanding mechanical performance. Several studies have been demonstrated the efficiency of this retrofitting solution for increasing the mechanical strength and the displacement capacity of masonry material. In this paper the state-of-art of the most relevant achievements in the experimental investigations and numerical analysis of retrofitted masonry wall have been critically reviewed. Firstly, a detailed collection of several experimental tests using different textile reinforced mortar and/or fiber reinforced mortar has been conducted. Special focus has been given to the test set-up and load configuration type adopted for experiments. Subsequently, several modelling techniques have been treated in order to detect the best approach simulating the interaction between reinforcement system and masonry ranging from macro and micro modelling, concentrated and diffused plasticity model and diverse constitutive laws. Finally, an overview of some original experimental outcomes from laboratory tests is presented. This results will play a major role in for the validation of the numerical models for the prediction of the shear strength and the ductile behavior of reinforced masonry that will be developed in a further step of this research