Seismic response analysis of skew bridges with pounding deck-abutment joints

In this paper the seismic response of short skew bridges with deck-abutment pounding joints is revisited. The permanent deck rotations and transverse displacements of such bridges after the recent earthquake in Chile created an incentive to revisit their non-conventional behaviour. A novel non-smooth rigid body approach is proposed to analyze the seismic response of pounding skew bridges which involves oblique frictional multi-contact phenomena. The coupling of the response, due to contact, is analysed in depth. It is shown that the tendency of skew bridges to exhibit transverse displacements and/or rotate (and hence unseat) after deck-abutment collisions is not a factor of the skew angle alone, but rather of the plan geometry plus friction. This is expressed with proposed dimensionless criteria. The study also unveils that the coupling is more pronounced in the low range of the frequency spectrum (short-period excitations/flexible structures) and presents novel dimensionless response spectra for the transverse displacements and rotations, triggered by oblique contact in a skew bridge subsystem. Despite the complexity of the response, the proposed spectra highlight a clear pattern. The dimensionless rotations, arising from contact, decline as the ratio of the structural versus excitation frequency increases and become practically negligible in the upper range of the frequency spectrum. Finally, a pilot application to a typical skew bridge is presented.     

Development and validation of a transition boiling model for RELAP5/MOD3 reflood simulation

The current version of the RELAP5/MOD3.1 code significantly underpredicts the transition boiling heat transfer during reflooding of hot fuel rods. In order to extend the code’s range of application for LOCA and degraded core analyses, a new transition boiling model has been developed, assessed and implemented. The model is based entirely on local state variables calculated by the code (wall and fluid temperatures, pressure, void fraction, mass flux and static quality) and does not rely on other history parameters, such as quench position or CHF and minimum film boiling temperatures. A number of separate-effect and bundle experiments are analyzed with the modified version of the code, and the predictions are compared with the ones obtained by the current version and with available experimental data. In all cases, the predictions of the improved model better fit the measured data. The shape of the new temperature curves is more physically and conceptually sound than the one calculated by the current version of the code.     

Did the 65 mph speed limit save lives?

In 1987, most states raised the speed limit from 55 to 65 mph on portions of their rural interstate highways. There was intense debate about the increase, and numerous evaluations were conducted afterwards. These evaluations share a common problem: they only measure the local effects of the change. But the change must be judged by its system-wide effects. In particular, the new 65 mph limit allowed the state highway patrols to shift their resources from speed enforcement on the interstates to other safety activities and other highways--a shift many highway patrol chiefs had argued for. If the chiefs were correct, the new allocation of patrol resources should lead to a reduction in statewide fatality rates. Similarly, the chance to drive faster on the interstates should attract drivers away from other, more dangerous roads, again generating system-wide consequences. This study measures these changes and obtains surprising results. We find that the 65 mph limit reduced statewide fatality rates by 3.4% to 5.1%, holding constant the effects of long-term trend, driving exposure, seat belt laws, and economic factors.     

Transformation of the Lyme disease spirochete Borrelia burgdorferi with heterologous DNA

Studies of the spirochete Borrelia burgdorferi have been hindered by the scarcity of genetic tools that can be used in these bacteria. For the first time, a method has been developed by which heterologous DNA (DNA without a naturally occurring B. burgdorferi homolog) can be introduced into and persistently maintained by B. burgdorferi. This technique uses integration of circular DNA into the bacterial genome via a single-crossover event. The ability to transform B. burgdorferi with heterologous DNA will now permit a wide range of experiments on the biology of these bacteria and their involvement in the many facets of Lyme disease.     

A longitudinal study of blood pressure in relation to performance on the Wechsler Adult Intelligence Scale

A growth curve analysis was used to examine estimated longitudinal decline (over 19 years) on the Wechsler Adult Intelligence Scale (WAIS; D. Wechsler, 1955) in relation to arterial hypertension and blood pressure (BP) for 55 men and 85 women (40 to 70 years old) who were free from overt major coexisting diseases. BP was associated with longitudinal decline for Visualization-Performance (VP) ability and Speed. Hypertension was a weaker predictor of VP and was unrelated to Speed. Age effects on VP were overestimated when averaged BP level, particularly systolic BP, was not controlled statistically. It was concluded that initial BP level and hypertension predict age-related longitudinal decline in specific major abilities assessed by the WAIS but that BP averaged over examinations is a stronger predictor.     

A three-unit standby redundant system with repair and preventive maintenance

This paper deals with the reliability of a renewable three-unit system under preventive maintenance activity. The Laplace transform of the reliability function and the mean lifetime of the system have been obtained under the assumption that the failure times, repair times, inspection times and maintenance times are random variables having different distributions. Some special cases also have been obtained.     

The herpes simplex virus type 1 origin binding protein. Specific recognition of phosphates and methyl groups defines the interacting surface for a monomeric DNA binding domain in the major groove of DNA

The UL9 gene of herpes simplex virus type 1 (HSV-1) encodes an origin binding protein (OBP). It is an ATP-dependent DNA helicase and a sequence-specific DNA-binding protein. The latter function is carried out by the C-terminal domain of OBP (DeltaOBP). We have now performed a quantitative analysis of the interaction between DeltaOBP and its recognition sequence, GTTCGCAC, in oriS. Initially optimal conditions for binding were carefully determined. We observed that complexes with different electrophoretic mobilities were formed. A cross-linking experiment demonstrated that nonspecific complexes containing 2 or more protein monomers per DNA molecule were formed at high protein concentrations. The specific complex formed at low concentrations of DeltaOBP had an electrophoretic mobility corresponding to a 1:1 complex. We then demonstrated that the methyl groups of thymine in the major groove were essential for high affinity binding. Changes in the minor groove had considerably smaller effects. Ethylation interference experiments indicated that specific contacts were made between OBP and three phosphates in the recognition sequence. Finally, these observations were used to present a model of the surface of DNA that interacts with DeltaOBP in a sequence-specific manner.     

Anticentromere antibodies in rheumatologic practice are not consistently associated with scleroderma

Anticentromere antibodies identified by indirect immunofluorescence are a valuable aid to the diagnosis and prognosis of patients with systemic sclerosis since they are associated in 50% to 80% of cases with limited cutaneous systemic sclerosis, a pattern usually associated with a good prognosis. We studied clinical presentations in rheumatology patients with anticentromere antibodies by indirect immunofluoresence and by ELISA and/or Western blot, but without scleroderma or Raynaud's phenomenon. Eight of 34 (23.5%) rheumatology clinic patients with centromere antibodies met these criteria, seven women and one man, with a median symptom duration of six years (range 1-20 years). Four had Sj?gren's syndrome, one had isolated xerostomia, one systemic lupus erythematosus, one seronegative symmetric polyarthritis and one primary biliary cirrhosis with arthralgia. The mean anticentromere antibody titer in these eight patients was similar to that in the patients who had at least Raynaud's phenomenon. Given the low incidence of scleroderma, these data illustrate the poor predictive value of anticentromere antibodies for the diagnosis of scleroderma in rheumatology clinic patients.     

Introduction to the Special Section on Health and Cognitive Function.

Numerous factors related to health and diseases have been studied in relation to cognitive function. It has been shown that across the life span, systemic medical diseases can negatively impact cognitive function. Factors that influence the development of medical diseases, such as poor health habits, biological risk factors, hormones, genetic factors, exposure to environmental toxins, and certain treatments for disease, can also have an adverse effect on cognitive function. Conversely, factors such as high levels of education, good health habits, and some treatments for disease can be protective. Included in this special section are 6 empirical articles that examine the relation of health or disease to cognitive function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuromorphic Synapses for Artificial Dendrites

We describe neuromorphic, variable-weight synapses onartificial dendrites that facilitate experimentation with correlativeadaptation rules. Attention is focused on those aspects of biologicalsynaptic function that could affect a neuromorphic network'scomputational power and adaptive capability. These include sublinearsummation, quantal synaptic noise, and independent adaptationof adjacent synapses. The diffusive nature of artificial dendritesadds considerable flexibility to the design of fast synapsesby allowing conductances to be enabled for short or for variablelengths of time. We present two complementary synapse designs:the shared conductance array and the self-timed synapse. Bothsynapse circuits behave as conductances to mimic biological synapsesand thus enable sublinear summation. The former achieves weightvariation by selecting different conductances from an on-chiparray, and the latter by modulating the length of time a constantconductance remains activated. Both work with our interchip communicationsystem, virtual wires. For the present purpose of comparing variousadaptation mechanisms in software, synaptic weights are storedoff chip. This simplifies the addition of quantal weight noiseand allows connections from different sources to the same dendriticcompartment to have independent weights.