Peak structural response to nonstationary random excitations

Study establishes distribution function of peak response values, based on frequency interpretation. Excitations considered include impact loading on landing gears and aircraft gust loading. Because of relative severity of excitations, prediction of fatigue and maximum response characteristics is important part of task of structural analysis and design

A note on the first passage time problem

Kolmogoroff backward equation for analyzing first passage time problem for linear single degree of freedom vibratory system with linear viscous dampin

Optimum structural design based on reliability and proof-load testing

Proof-load test eliminates structures with strength less than the proof load and improves the reliability value in analysis. It truncates the distribution function of strength at the proof load, thereby alleviating verification of a fitted distribution function at the lower tail portion where data are usually nonexistent

On the bound of first excursion probability

Boundary values for first excursion probability as related to reliability and safe performance of mechanical and structural system

Assessment of Molecular Cytogenetic Methods for the Detection of Chromosomal Abnormalities

Some marker chromosomes and chromosome rearrangements are difficult to identify using G-bands by Giemsa staining after trypsin treatment (G-banding) alone. Molecular cytogenetic techniques, such as spectral karyotyping (SKY) and fluorescence in situ hybridization (FISH), can help to detect chromosomal aberrations precisely. We analyzed the karyotypes in 6 cases of multiple congenital abnormalities and 1 case of spontaneous abortion (case 2). Three cases (cases 1, 6, and 7) had marker chromosomes, and 4 cases (cases 2-5) had chromosomal rearrangements. The karyotypes in cases 1, 2, and 3 were determined using FISH with probes based on the clinical findings and family histories. Spectral karyotyping (SKY) analysis in cases 4-7 showed that this method is useful and saves time. The combination of SKY and FISH analyses defi ned the range of the ring chromosome in case 7. We demonstrated that a combination of G-banding, FISH, and SKY can be applied effectively to the investigation of chromosomal rearrangement and to the detection of marker chromosome origins. We suggest the use of these methods for prenatal diagnosis, in which the inherent time limitations are particularly important

Structural Reliability Estimation with Vibration-Based Identified Parameters

This paper presents a unique structural reliability estimation method incorporating structural parameter identification results based on the seismic response measurement. In the shaking table test, a three-bent concrete bridge model was shaken to different damage levels by a sequence of earthquake motions with increasing intensities. Structural parameters, stiffness and damping values of the bridge were identified under damaging seismic events based on the seismic response measurement. A methodology was developed to understand the importance of structural parameter identification in the reliability estimation. Along this line, a set of structural parameters were generated based on the Monte Carlo simulation. Each of them was assigned to the base bridge model. Then, every bridge model was analyzed using nonlinear time history analyses to obtain damage level at the specific locations. Last, reliability estimation was performed for bridges modeled with two sets of structural parameters. The first one was obtained by the nonlinear time history analysis with the Monte Carlo simulated parameters which is called nonupdated structural parameters. The second one was obtained by updating the first set in Bayesian sense based on the vibration-based identification results which is called updated structural parameters. In the scope of this paper, it was shown that residual reliability of the system estimated using the updated structural parameters is lower than the one estimated using the nonupdated structural parameters

Thrombocytopenia in Preterm Infants with Intrauterine Growth Restriction

Sick preterm infants often have thrombocytopenia at birth, and this is often associated with intrauterine growth restriction (IUGR), or birth weights less than the 10th percentile. The pathogenesis of the thrombocytopenia and its importance in IUGR are still unclear. We studied the characteristics of preterm IUGR infants with thrombocytopenia. Twenty-seven singleton Japanese preterm IUGR infants were born between January 2002 and June 2007 at Okayama University Hospital. Infants with malformation, chromosomal abnormalities, alloimmune thrombocytopenia, sepsis, and maternal aspirin ingestion were excluded. The infants were divided into group A (n&#65309;8), which had thrombocytopenia within 72h after birth, and group B (n&#65309;19), which did not. There were significant differences in birth weight, head circumference, umbilical artery (UA)-pulsatility index (PI), middle cerebral artery-PI, UA-pH, UA-pO2, and UA-pCO2. The infants in group A were smaller, had abnormal blood flow patterns, and were hypoxic at birth. We speculate that the infants with thrombocytopenia were more severely growth-restricted by chronic hypoxia. Thrombocytopenia is an important parameter for chronic hypoxia in the uterine.</p

Synthesis of satellite (MODIS), aircraft (ICARTT), and surface (IMPROVE, EPA-AQS, AERONET) aerosol observations over eastern North America to improve MODIS aerosol retrievals and constrain surface aerosol concentrations and sources

We use an ensemble of satellite (MODIS), aircraft, and ground-based aerosol observations during the ICARTT field campaign over eastern North America in summer 2004 to (1) examine the consistency between different aerosol measurements, (2) evaluate a new retrieval of aerosol optical depths (AODs) and inferred surface aerosol concentrations (PM2.5) from the MODIS satellite instrument, and (3) apply this collective information to improve our understanding of aerosol sources. The GEOS-Chem global chemical transport model (CTM) provides a transfer platform between the different data sets, allowing us to evaluate the consistency between different aerosol parameters observed at different times and locations. We use an improved MODIS AOD retrieval based on locally derived visible surface reflectances and aerosol properties calculated from GEOS-Chem. Use of GEOS-Chem aerosol optical properties in the MODIS retrieval not only results in an improved AOD product but also allows quantitative evaluation of model aerosol mass from the comparison of simulated and observed AODs. The aircraft measurements show narrower aerosol size distributions than those usually assumed in models, and this has important implications for AOD retrievals. Our MODIS AOD retrieval compares well to the ground-based AERONET data (R = 0.84, slope = 1.02), significantly improving on the MODIS c005 operational product. Inference of surface PM2.5 from our MODIS AOD retrieval shows good correlation to the EPA-AQS data (R = 0.78) but a high regression slope (slope = 1.48). The high slope is seen in all AOD-inferred PM2.5 concentrations (AERONET: slope = 2.04; MODIS c005: slope = 1.51) and could reflect a clear-sky bias in the AOD observations. The ensemble of MODIS, aircraft, and surface data are consistent in pointing to a model overestimate of sulfate in the mid-Atlantic and an underestimate of organic and dust aerosol in the southeastern United States. The sulfate overestimate could reflect an excessive contribution from aqueous-phase production in clouds, while the organic carbon underestimate could possibly be resolved by a new secondary pathway involving dicarbonyls