Effect of Vehicle Velocity on the Dynamic Amplification of a Vehicle Crossing a Simply Supported Bridge

Many writers, using both experimental tests and complex numerical models, have examined the effect of vehicle velocity on a highway bridge’s dynamic amplification. Although these tests and models give valuable quantitative information on dynamic amplification, they give little insight into how amplification is affected by individual vehicle/bridge parameters. This paper uses relatively simple numerical models to investigate the effect of vehicle velocity on a bridge’s dynamic amplification. A single vehicle crossing a simply supported bridge is modeled as a constant point force. A set of critical velocities are determined associated with peaks of dynamic amplification for all beams. The reasons for these large amplifications are discussed. A more complex finite element model, validated with field tests, is used to test the applicability of the conclusions obtained from the simple models to a realistic bridge/vehicle system.     

Secretion of CTLA4Ig by an SV40 T antigen-transformed islet cell line inhibits graft rejection against the neoantigen

We found that cytochrome c (Cyt c) could oxidize cardiolipin (CL), and detected monoepoxides of linoleic acid (LA) in the fatty acids constituting the oxidized CL. We also found that in the presence of CL and Cyt c, free LA was oxidized and LA monoepoxides were produced. The aim of this study was to elucidate the mechanism of this lipid peroxidation. We concluded that ferric Cyt c produced some radical species from water-soluble oxygen in the presence of CL (CL-Cyt c system) and that radicals oxidized free LA or CL. The CL-Cyt c system may be another LA monoepoxide producing system in the neutrophil and may account for the lipid peroxidation observed in the ischemia-reperfusion-induced cardiac injury.     

The ECG diagnosis of acute myocardial infarction in the presence of left bundle branch block

The electrocardiographic diagnosis of ischemic heart disease is made more difficult in the setting of confounding patterns, including left bundle branch block (LBBB). The electrocardiographic detection of abnormalities arising from acute ischemic cardiac disease in this setting is possible in certain cases, contrary to popular medical opinion. Several strategies are available to assist in the correct interpretation of the electrocardiogram (ECG) with LBBB and potential acute ischemia, including: (1) a knowledge of the anticipated ST segment-T wave morphologies of LBBB and, consequently, the ability to recognize ischemic changes; (2) the performance of serial ECGs demonstrating dynamic change; and (3) a comparison to previous ECGs. The first strategy, an awareness of the anticipated ST segment morphologies of LBBB, is the most important and not dependent on additional diagnostic testing or past medical records.     

Integration of stress research in rheumatoid arthritis: from Alexander to Zautra and back again

Patients with nasal obstruction often have associated snoring. It is uncertain whether surgery, which relieves the nasal obstruction, will also relieve the snoring. We have reviewed 96 patients who complain of both nasal obstruction and snoring and who underwent nasal surgery. Snoring was completely relieved in 48 patients (50%), was less loud in a further 38 patients (40%), unchanged in 8 patients, and louder in 2. Patients who had nasal polypectomy as part of their nasal surgery obtained the greatest snoring relief. The relationship between nasal obstruction and snoring is complex and the alteration of airflow patterns after nasal surgery is postulated to be important in influencing snoring relief. This study suggests that, when snoring and nasal obstruction coexist, nasal surgery should be considered as the first line of surgical treatment.     

Use of the MTT assay in adult ventricular cardiomyocytes to assess viability: effects of adenosine and potassium on cellular survival

This study used the colorimetric MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide)] assay to assess cell viability in isolated quiescent adult guinea-pig ventricular myocytes exposed to different insults or cardioprotective conditions, including adenosine and hyperkalemic-cardioplegia. Optical density (OD), reflecting intracellular reduction of MTT into formazan pigment formation, was a function of the number of viable cells (coefficient of linear correlation approximately 0.99), with MTT reduction preferentially carried out by rod-shaped cardiomyocytes (absorbance at 1.009 +/- 0.013 and 0.006 +/- 0.001 OD units for populations containing 50 and 0% of rod-shaped cells). Following prolonged mechanical (pressure of 1 lb/min for 40 min), chemical (10% DMSO or ethanol) or hypoxic injury (N2-saturated solution), the MTT reductase activity reflected reduction in the number of viable cells by 87%, >50%, and 77%, respectively. In cardiomyocytes exposed to a 40 min hypoxia (with CO2), the MTT reductase activity was 0.056 +/- 0.009 in the absence, and 0.074 +/- 0.008 OD units in the presence of adenosine (1 mM), i.e. adenosine reduced the number of non-viable cells. Also, the MTT assay revealed that the effect of potassium-containing solutions (16 and 32 mM K+) on cellular viability may depend on the extent of insult imposed on cardiomyocytes; i.e. a approximately 24% and 49% increase under mild hypoxia (0.03% CO2), or an 18% decrease in cell viability under severe hypoxia (N2) in pre-injured cells. Thus, the MTT assay used to assess viability of isolated adult cardiomyocytes revealed a direct cytoprotective effect of adenosine and hyperkalemic-cardioplegia by promoting cell survival under certain conditions in vitro.     

Rapid DNA sequencing of more than 1000 bases per run by capillary electrophoresis using replaceable linear polyacrylamide solutions

The read length for DNA sequencing using capillary electrophoresis and replaceable linear polyacrylamide (LPA) solutions has been extended to more than 1000 bases with a run time of 80 min. This result was successfully achieved through the combined use of cycle sequencing with dye-labeled primers, improved matrix and separation conditions, and enhanced base-calling software. The influences of LPA molecular weight and concentration on separation were investigated. Additionally, the separation buffer, column temperature, and electric field were adjusted to increase the number of resolvable DNA fragments per run while maintaining an enhanced separation speed. Using low concentrations [2% (w/v)] of high molecular weight LPA polymers (> 5.5 x 10(6) Da), elevated column temperature (50 degrees C) and moderately high field (150 V/cm), rapid sequencing analysis for more than 1000 bases on a model ssM13mp18 template was obtained with 96.8% accuracy.     

Screening for PTSD in a substance abuse sample: psychometric properties of a modified version of the PTSD Symptom Scale Self-Report. Posttraumatic stress disorder

The high rate of posttraumatic stress disorder (PTSD) among substance use disorder (SUD) patients has been documented in research protocols, but there is evidence that it is markedly under-diagnosed in clinical settings. To address the need for a brief self-report measure to identify SUD patients who may benefit from further assessment and/or treatment for PTSD, the psychometric properties of a modified version of the PTSD Symptom Scale Self-Report (PSS-SR) were examined in a treatment-seeking SUD sample (N = 118). The modified version of the PSS-SR, which measures both frequency and severity of PTSD symptoms, demonstrated good internal consistency reliability and was correlated with other self-report measures of trauma-related symptomatology. Comparisons between a structured PTSD diagnostic interview and the modified PSS-SR indicated that 89% of the PTSD positive patients were correctly classified by the modified PSS-SR. The clinical relevance of these findings was discussed.     

The hysteresis loops of magnetic ferrites and the processes involved in their formation

It is shown that a specimen's microstructure affects the form of its magnetization curves but notM _s, the saturation magnetic moment per cm³ norH _s, the applied field strength required for saturation. A procedure is then given for the precise determination ofM _s andH _s using data derived from the hysteresis loops of polycrystalline isotropic specimens. The procedure is simple to use and avoids the laborious extrapolation requirements of the “law of approach”. Finally, the magnetization processes involved in forming the hysteresis loops betweenH _s and —H _s are described.     

Involvement of residues 296-299 in the enzymatic activity of tissue-type plasminogen activator

The tetra-alanine substitution variant KHRR 296–299 AAAAof tissue-type plasminogen activator (t-PA) was previously shownto have enhanced fibrin specificity and enhanced activity inthe presence of fibrin compared with the wild-type form of themolecule. The structural requirements for these alterationsin enzymatic activity were investigated by constructing severalamino acid substitution variants at each of the positions from296 to 299 and evaluating their activities under a variety ofconditions. Effects on plasminogen activator activity were commonamong the point mutants at positions 296–299; nearly allhad a phenotype similar to the KHRR 296–299 AAAA variant.The greatest effects on enzymatic function were found with multiplesubstitution variants, but some single charge reversals andproline substitutions had substantial effects. The enhancedfibrin specificity of KHRR 296–299 AAAA t-PA results inless fibrinogenolysis than seen with wild-type t-PA. Approximatelyfour times greater concentration of KHRR 296–299 AAAAcompared with wild-type t-PA was required to consume 50% ofthe fibrinogen in human plasma.