Two-dimensional ultrasonic strain rate measurement of the human heart in vivo

A study is presented in which the feasibility of two-dimensional strain rate estimation of the human heart in vivo has been demonstrated. To do this, ultrasonic B-mode data were captured at a high temporal resolution of 3.8 ms and processed off-line. The motion of the RF signal patterns within the two-dimensional sector image was tracked and used as the basis for strain rate estimation. Both axial and lateral motion and strain rate estimates showed a good agreement with the results obtained by more established, one-dimensional techniques     

Simulation of the biomechanical behavior of the skin in virtual surgical applications by finite element method

The objective of this study was to develop a software application that is able to support plastic surgeons interested in applying simulations and soft tissue modeling during presurgical planning activities. By using our user-friendly interface and force-displacement graphs, users can analyze scalp skin behaviors when subjected to stress. Users can 1) determine the dynamic of a general point of scalp skin after the application of a specific force, 2) predict the force needed for displacement of a point, and 3) study the deformation of all the points of the entire scalp based on the force applied. Results showed how users are able to manipulate and analyze mechanical behaviors on a mechanical model rather than on a pure geometric qualitative physiological model. The entire application was developed on a Silicon Graphics workstation.     

Modulated Crosslinking of Polyolefins through Radical Processes in the Melt

Summary: The possibility to submit a semi‐crystalline polyolefin (or a mixture of different polyolefins) to a phase selective crosslinking process, in order to produce a material with unchanged crystallinity but a partially crosslinked amorphous fraction, has been investigated. The crosslinking process has been performed in the melt in the presence of radical initiators. Three different polymer systems have been considered: a LLDPE sample (an ethylene‐1‐butene 91/9 w/w copolymer), two EVA samples (ethylene‐vinyl acetate copolymers containing a different amount (10 and 15 wt.‐%) of acetate monomer units), and mixtures of LLDPE with polybutadiene (BR) (90/10 w/w). All the reaction products have been characterized by selective solvent extractions to determine the gel content, by analysis with different spectroscopies (IR and NMR) and by viscosity measurements to evaluate changes of the structure and the molecular weight (MW) of the partially crosslinked samples. Finally DSC and DMTA analyses have been used to correlate the variations of the macromolecule structure to the thermo‐mechanical properties and, in the case of the mixtures, TEM analysis has been carried out to gather information about the morphology.

TEM micrograph of the partially crosslinked polyethylene/polybutadiene blend 90/10 (w/w).     

Ordering and Path Constraints over Semistructured Data

Constraints are a valuable tool for managing information. Feature constraints have been used for describing records in constraint programming (Aït-Kaci and Podelski, 1993; Smolka and Treinen, 1994) and record like structures in computational linguistics (Kaplan and Bresnan, 1982; Shieber, 1986). In this paper, we consider how constraint-based technology can be used to query and reason about semistructured data. The constraint system FT (Müller et al., 1997) provides information ordering constraints interpreted over feature trees. Here, we show how a generalization of FT combined with path constraints can be used to formally represent, state constraints, and reason about semistructured data. The constraint languages we propose provide possibilities to straightforwardly capture, for example, what it means for a tree to be a subtree or subsumed by another, or what it means for two paths to be divergent. We establish a logical semantics for our constraints thanks to axiom schemes presenting our first-order theory constraint system. We propose using the constraint systems for querying semistructured data.     

Fragility versus excessive crash involvement as determinants of high death rates per vehicle-mile of travel among older drivers

Using multiple national data systems, the roles of fragility (susceptibility to injury) versus excessive crash involvement in the increased fatality risk of older drivers per vehicle-mile of travel (VMT) were estimated. For each age and gender group, deaths per driver involved in a crash (a marker of fragility) and drivers involved in crashes per VMT (a marker of excessive crash involvement) were computed. Compared with drivers ages 30-59, those younger than 20 and those 75 or older both had much higher driver death rates per VMT. The highest death rates per mile driven, 13-fold increases, were observed among drivers age 80 or older, who also had the highest death rates per crash. Fragility began to increase at ages 60-64 and increased steadily with advancing age, accounting for about 60-95% of the excess death rates per VMT in older drivers, depending on age group and gender. Among older drivers, marked excesses in crash involvement did not begin until age 75, but explained no more than about 30-45% of the elevated risk in this group of drivers; excessive crashes explained less of the risk among drivers ages 60-74. In contrast, crash over-involvement was the major factor contributing to the high risk of death among drivers younger than 20, accounting for more than 95% of their elevated death rates per VMT. Although both fragility and crash over-involvement contributed to the excess death rates among older drivers per VMT, fragility appeared to be of over-riding importance. These findings suggest that measures to improve the protection of older vehicle occupants in crashes should be vigorously pursued.     

Electromagnetic humidity sensor for industrial applications

The letter describes an electromagnetic humidity sensor based on a resonance perturbation technique. The proposed sensor is capable of measuring humidity over a wide dynamic range in an industrial environment and is insensitive to dust, dirt, oil vapours etc. The all-metal construction of the sensor makes it immune to damage by high temperature. The sensor signal processing circuit provides a time-dependent signal which can be directly applied to any modern computerised control systems.     

Fatal crashes of passenger vehicles before and after adding antilock braking systems

Fatal crash rates of passenger cars and vans were compared for the last model year before four-wheel antilock brakes were introduced and the first model year for which antilock brakes were standard equipment. Vehicles selected for analysis had no other significant design changes between the model years being compared, and the model years with and without antilocks were no more than two years apart. The overall fatal crash rates were similar for the two model years. However, the vehicles with antilocks were significantly more likely to be involved in crashes fatal to their own occupants, particularly single-vehicle crashes. Conversely, antilock vehicles were less likely to be involved in crashes fatal to occupants of other vehicles or nonoccupants (pedestrians, bicyclists). Overall, antilock brakes appear to have had little effect on fatal crash involvement. Further study is needed to better understand why fatality risk has increased for occupants of antilock vehicles.     

A Longitudinal Analysis of PTSD Symptom Course: Delayed-Onset PTSD in Somalia Peacekeepers.

Posttraumatic stress disorder (PTSD) typically follows an acute to chronic course. However, some trauma victims do not report significant symptoms until a period of time has elapsed after the event. Although originally dismissed as an artifact of retrospective methodologies, recent prospective studies document apparent instances of delayed-onset PTSD. Little is known currently about factors associated with the delayed onset of PTSD. This study was designed to examine the course of PTSD in a sample of 1,040 U.S. military peacekeepers who served in Somalia. A small but nontrivial subset of participants endorsed clinically significant levels of PTSD after a period of minimal distress, the magnitude of which cannot be ascribed to minor waxing and waning of symptoms. War-zone exposure and perceived meaningfulness of the mission, as rated by soldiers after returning to the United States, predicted symptom course over the next 18 months. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of nitrapyrin on nitrapyrin residues and nitrate content in red beet roots fertilised with urea

The effect of nitrapyrin [2-chloro-6-(trichloromethyl)pyridine] application on nitrapyrin residues and nitrate content in red beet (Beta vulgaris L. var. conditiva) roots and in soil fertilised with urea was studied during the 1977 growing season. The nitrapyrin residues in roots were on 15 August between 0.00–1.19 μg g^?1 and on 1 October between 0.00–0.45 μg g^?1 (dry weight basis) correlating significantly r = 0.99, P<0.01) to the rates of nitrapyrin applied on 8 June (0–34 kg ha^?1). The content of nitrapyrin in roots decreased in autumn having in August-September a ‘biological half-life’ of 3 weeks. In soil the same parameter was in July-September more than 4 months. The ratio of nitrapyrin to its main breakdown product varied in soil between 3.5–24.8 and in red beets between 0.6–1.4. Neither of these compounds were found in processed canned red beets. Nitrapyrin treatment decreased the nitrate content in both soil and beets. The inhibitor application of 18 kg ha^?1 caused the highest reduction of the NO₃-nitrogen content in beets, the average values on dry weight basis being 0.51–0.34 mg g^?1 for 0–18 kg ha^?1 nitrapyrin application, respectively. The reduction of NO₃-nitrogen in beets from its level of 15 August to its September level was 44%. After 5 September the reduction of the nitrate level in beets was not significant.