A method for detecting changes in left ventricular mass during variations in filling volume

The study reported describes a combination of recombinant human bone morphogenetic protein-2 (rhBMP-2) and collagen (C) to regenerate bone. Unilateral critical-sized defects (CSDs) were prepared in radii of 32 skeletally mature New Zealand white rabbits. Rabbits were divided evenly among four treatments: autograft, absorbable C (Helistat), 35 microg of rhBMP-2 combined with absorbable C (rhBMP-2/C), and untreated CSDs. The two euthanasia periods were 4 and 8 weeks. Radiographs were taken the day of surgery, every 2 weeks, and at term and the percent of radiopacity was measured. Data analysis revealed a time-dependent increase in the percent radiopacity with rhBMP-2/C. Histological examination revealed the rhBMP-2/C treatment regenerated osseous contour by 8 weeks. According to quantitative histomorphometry, the CSD and C groups had significantly less new bone than either autograft or rhBMP-2/C (p < or = 0.05). The results suggest that rhBMP-2/C could be an effective therapy to restore segmental bone defects.     

Crosstalk Characterization in Geiger-Mode Avalanche Photodiode Arrays

Following our work on Geiger-mode avalanche photodiode arrays, we have recently been dealing with the crosstalk issue in newly developed dense arrays with a minimum distance between pixel centers of 84 mum. In this paper, we present our crosstalk measurement approach, including the experimental setup and the offline calculation methods. Different characterizations of the crosstalk probability P_CT versus capacitance have been performed to extrapolate the P_CT when no measurement setup loads the pixels. We also present results regarding the crosstalk probability versus pixel distance and bias. Moreover, by adopting a slightly different approach, the probability density decay time has been measured to investigate about crosstalk origin.     

Volcano–tectonic structures, gravity and helium in geothermal areas of Tuscany and Latium (Vulsini volcanic district), Italy

Since the early 1980s, geological and structural mapping, gravity, and helium soil–gas studies have been performed in the eastern sector of the Vulsini Volcanic District (Roman Magmatic Province) in an attempt to locate potential geothermal reservoirs. This area is characterised by an anomalous geothermal gradient of >100°C/km, and by widespread hydrothermal mineralization, thermal springs, high gas fluxes, and fossil and current travertine deposits. The results of these surveys indicate the existence of a number of fault systems, with N–S and E–W structures that appear to be superimposed on older NW–SE and NE–SW features. Comparison of the results of the various studies also reveals differences in permeability and potential reservoir structures at depth.     

A hierarchical distributed-shared memory parallel Branch&Bound application with PVM and OpenMP for multiprocessor clusters

Branch&Bound (B&B) is a technique widely used to solve combinatorial optimization problems in physics and engineering science. In this paper we show how the combined use of PVM and OpenMP libraries can be a promising approach to exploit the intrinsic parallel nature of this class of application and to obtain efficient code for hybrid computational architectures. We described how both the shared memory and the distributed memory programming models can be applied to implement the same algorithm for the inter-nodes and intra-node parallelization. Some experimental tests on a local area network (LAN) of workstations are finally discussed.     

Theoretical modelling of arteriovenous malformation rupture risk: a feasibility and validation study

PURPOSE: To explore the feasibility of using a theoretical computational model to simulate the risk of spontaneous arteriovenous malformation (AVM) haemorrhage. METHODS: Data from 12 patients were collected from a prospective databank which documented the angioarchitecture and morphological characteristics of the AVM and the feeding mean arterial pressure (FMAP) measured during initial superselective angiography prior to any treatment. Using the data, a computational model of the cerebral circulation and the AVM was constructed for each patient (patient-specific model). Two model risk (Risk(model)) calculations (haemodynamic- and structural-weighted estimates) were performed by using the patient-specific models. In our previously developed method of haemodynamic-weighted estimate, Risk(model) was calculated with the simulated intranidal pressures related to its maximal and minimal values. In the method of structural-weighted estimate developed and described in this paper, the vessel mechanical properties and probability calculation were considered in more detail than in the haemodynamic-weighted estimate. Risk(model) was then compared to experimentally determined risk which was calculated using a statistical method for determining the relative risk of having initially presented with AVM haemorrhage, termed Risk(exp). RESULTS: The Risk(model) calculated by both haemodynamic- and structural-weighted estimates correlated with experimental risks with chi2 = 6.0 and 0.64, respectively. The risks of the structural-weighted estimate were more correlated to experimental risks. CONCLUSIONS: Using two different approaches to the calculation of AVM haemorrhage risk, we found a general agreement with independent statistical estimates of haemorrhagic risk based on patient data. Computational approaches are feasible; future work can focus on specific pathomechanistic questions. Detailed patient-specific computational models can also be developed as an adjunct to individual patient risk assessment for risk-stratification purposes.     

Intestinal obstruction due to Meckel's diverticulum. Description of three cases

Among 588 small bowel mechanical obstructions operated since January 1982 until December 1996 at the Flajani Surgery Department and Emergency Department of the San Camillo Hospital in Rome, 3 male patients were operated for intestinal obstruction due to Meckel's diverticulum. In one case, obstruction was caused by a small bowel volvulus rolling on a Meckel's diverticulum, whose gangrenous extremity was "blocked" on caecum. In the other two cases, intestinal loops were incarcerated into an internal hernial ring constituted by the same diverticulum whose inflamed extremity was fixed to corresponding mesentery. We examined embryologic and clinical aspects of the pathology here considered, particularly its complications, obstruction being the most common in adult age. Diagnosis is often misunderstood, since a complicated Meckel's diverticulum simulates many other abdominal pathologies. A straight radiography and an ultrasonography of the abdomen may be useful to reach the correct diagnosis. We performed diverticulectomy, using a linear stapler and we underline the opportunity of this method. In young age laparoscopy resection is considered the gold treatment of this pathology by some authors. We didn't observe any mortality, although one of our patients was in a severe septic condition. It is necessary to examine the last ileal 100 centimetres when a suspected acute appendicitis is not initially found by operation. The opportunity of a promptly performed operation is underlined to prevent that such a benign pathology may induce also exitus.     

Aspects of Qubit Dynamics in the Presence of Leakage

Nano-electronics devices such as small-capacitance Josephsonjunction circuits appear to be promising systems to implementquantum logic. While the elementary unit of a quantum computeris a two-state system (the qubit) the computational space of aJosephson junction qubit is a subset of a larger Hilbertspace. Therefore quantum leakage may occur, i.e. during theoperation of the device the quantum state may escape partiallyfrom the computational subspace. We study the consequences ofleakage for the fidelity of Josephson qubits and discuss howthe gate design can be optimized.