P. Waldron

Acute chest syndrome (ACS) is the leading cause of hospitalization, morbidity, and mortality in patients with sickle cell disease. Radiographic and clinical findings in ACS resemble pneumonia; however, etiologies other than infectious pathogens have been implicated, including pulmonary fat embolism (PFE) and infarction of segments of the pulmonary vasculature. The National Acute Chest Syndrome Study Group was designed to identify the etiologic agents and clinical outcomes associated with this syndrome. Data were analyzed from the prospective study of 671 episodes of ACS in 538 patients with sickle cell anemia. ACS was defined as a new pulmonary infiltrate involving at least 1 complete segment of the lung, excluding atelectasis. In addition, the patients had to have chest pain, fever >38.5C, tachypnea, wheezing, or cough. Samples of blood and deep sputum were analyzed for evidence of bacteria, viruses, and PFE. Mycoplasma pneumoniae infection was determined by analysis of paired serologies. Detailed information on patient characteristics, presenting signs and symptoms, treatment, and clinical outcome were collected. Fifty-one (9%) of 598 episodes of ACS had serologic evidence of M pneumoniae infection. Twelve percent of the 112 episodes of ACS occurring in patients younger than 5 years were associated with M pneumoniae infection. At the time of diagnosis, 98% of all patients with M pneumoniae infection had fever, 78% had a cough, and 51% were tachypneic. More than 50% developed multilobar infiltrates and effusions, 82% were transfused, and 6% required assisted ventilation. The average hospital stay was 10 days. Evidence of PFE with M pneumoniae infection was seen in 5 (20%) of 25 patients with adequate deep respiratory samples for the PFE assay. M pneumoniae and Chlamydia pneumoniae was found in 16% of patients with diagnostic studies for C pneumoniae. Mycoplasma hominis was cultured in 10 (2%) of 555 episodes of ACS and occurred more frequently in older patients, but the presenting symptoms and clinical course was similar to those with M pneumoniae. M pneumoniae is commonly associated with the ACS in patients with sickle cell anemia and occurs in very young children. M hominis should be considered in the differential diagnosis of ACS. Aggressive treatment with broad-spectrum antibiotics, including 1 from the macrolide class, is recommended for all patients as well as bronchodilator therapy, early transfusion, and respiratory support when clinically indicated.

ABSTRACT A one-fifth model reinforced-concrete beam-slab bridge deck was tested to destruction, and the vibrational response to ambient excitation was measured at different stages of cracking and spalling. Observations showed that the neutral axis remained close to the lower flange of the T-beam throughout the loading range. A method capable of assessing the load-carrying capacity as well as the structural condition of a T-beam slab bridge deck has been developed. This requires prior information on the geometric dimensions and fundamental modal frequency of the structure, and two methods are discussed and proposed for assessment. The results of a parametric study of the effect of different boundary conditions on the fundamental modal frequency are presented in this paper. Different potential sources of error in this process are discussed and the manner of implementing the method is presented.

Cytogenetic and molecular studies have demonstrated that involvement of 22q is a non-random finding in malignant rhabdoid tumors (MRTs) of the brain. We present an MRT of the kidney with the karyotype 47,XY, + i(1)(q10), der(8)t(8;22)(q12;q11.2),der(22)t(8;22)(q23 or q24.1;q11.2). This unbalanced reciprocal translocation was confirmed by fluorescence in situ hybridization (FISH) with chromosome-specific paints for chromosomes 8 and 22. Molecular analysis demonstrated a partial deletion of 22q in the BCR region at q11.2, strengthening the suspicion that this is a critical region for the initiation or progression of these highly malignant neoplasms. Establishing non-random cytogenetic changes in MRTs arising from the kidney may be of value in distinguishing these rare, but often fatal tumors from other renal neoplasms that mimic them histologically. The similarity in cytogenetic and molecular abnormalities between renal and extra-renal MRTs argues against the concept that extra-renal MRTs are only representative of a rhabdoid phenotype, rather than being true rhabdoid tumors.

... 2] on a range of parametrically varied foot-bridge structures ... Table 2. It should be noticed that the fundamental frequency (3.4 Hz) of the cable-stayed footbridge is margin ... For the purpose of assessing vibration serviceability, the guidelines of the UK code (BSI 1978) were taken as ...

This paper describes the application of the FE modelling, modal testing and FE model correlation and updating techniques to a 1500-tonne car park floor structure. Firstly, a pre-test FE model, constructed according to common civil engineering practice, is presented. Next, the modal testing performed on the structure is described and the results from this testing are shown. Finally, the manual FE model updating procedure as applied to this structure is described and the correlation between the updated FE model and the test results is presented. By using this procedure, inadequacies in the pre-test FE model are highlighted and suggestions are made for better modelling practice for similar future structures.

This paper describes the finite element modelling, dynamic testing and finite element model updating of a newly constructed, 35m span, cable-stayed footbridge. A numerical simulation, using an updated FE model, was conducted to evaluate the accelerations that would be induced by a walking pedestrian. The results from the simulation were compared to corresponding experimental measurements, and were found to be in good agreement.

This paper describes the analytical FE modelling, modal testing and FE model updating of two full-scale pedestrian footbridges. These procedures are well developed in the fields of mechanical and aerospace engineering, and have just started to be applied successfully to large civil ...