Electronic relaxation effects in condensed polyacenes: A high-resolution photoemission study.

We present a high-resolution photoelectron spectroscopy investigation of condensed films of benzene, naphthalene, anthracene, tetracene, and pentacene. High spectroscopic resolution and a systematic variation of the molecular size allow a detailed analysis of the fine structures. The line shapes of the C 1s main lines are analyzed with respect to the different contributions of inhomogeneous broadening, vibronic coupling, and chemical shifts. The shake-up satellite spectra reveal trends, which give insight into the charge redistribution within the molecule upon photoexcitation. In particular, the shake-up between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) increases in intensity and moves closer toward the C 1s main line if the size of the aromatic system is increased. An explanation is given on the basis of the delocalization of the aromatic system and its capability in screening the photogenerated core hole. A comparison of the HOMO-LUMO shake-up position to the optical band gap gives additional insight into the reorganization of the electronic system upon photoexcitation.

Endemicity and inter-city spread of Burkholderia cepacia genomovar III in cystic fibrosis.

OBJECTIVES: We sought to determine whether the same Burkholderia cepacia complex strain has persisted as the dominant clonal lineage among patients in a large cystic fibrosis (CF) treatment center during the past 2 decades. STUDY DESIGN: The inter-city spread of B cepacia through transfer of a colonized patient and the impact of infection control measures in containing inter-patient transmission were investigated. We analyzed all available B cepacia complex isolates recovered from 1981 to 1987 and from 1996 to 2000 at one large CF treatment center (Center A) and from 1997 to 2000 at another center (Center B). Incidence of B cepacia complex infection and infection control measures in both centers were assessed. RESULTS: Seventeen (81%) of 21 Center A patients from whom B cepacia complex bacteria were recovered between 1981 and 1987 and 40 (97%) of 41 patients culture-positive between 1996 and 2000 were infected with the same genomovar III strain. Transfer of a colonized patient from Center A to Center B was associated with an increase in B cepacia complex infection in Center B, all of which was with the Center A dominant strain. This strain, designated PHDC, lacks both B cepacia epidemic strain and cblA markers. CONCLUSIONS: B cepacia complex strains may remain endemic in CF treatment centers for many years. Responsible bacterial and host factors and optimal infection control measures to prevent inter-patient spread remain to be identified.

Echocardiography in cystic fibrosis: A proposed scoring system.

An echocardiographic scoring system was developed on the basis of an observed sequence of echo abnormalities, beginning with RV hypertrophy, through RV dilation, to abnormal RV systolic time intervals, noted to be associated with the progressive pulmonary disease of cystic fibrosis. This score correlated significantly with both the Shwachman-Kulczycki (r = 0.87, P < 0.001) and Taussig-NIH (r = 0.86, P < 0.001) clinical scoring systems, the Brasfield chest roentgenogram score (r = 0.86, P < 0.001), and pulmonary function test results. The scoring of echos appears to be useful for the early detection and systematic quantitation of the cardiac effects of the progressive pulmonary disease. Preliminary sequential echo studies suggest that this system provides a method for assessing the progression of cardiac disease and evaluating prognosis in individual patients, and may prove to be useful in monitoring therapeutic interventions for cor pulmonale.

Oral health status in relation to socioeconomic and ethnic characteristics of urban adults in the U.S.A.

Nearly 1,300 adult members of a prepaid medical group plan in New York City were screened through automated multiphasic health testing in a series of test stations including a dental station, during 1971-1973. Oral status indicators were developed including a number of missing teeth, scores to measure levels of gingival and periodontal disease, Simplified Oral Hygiene Index scores, and ratios of decayed teeth. Ratios of filled teeth were calculated to measure levels of restorative care. The present paper examines the interrelationships of economic status, education and ethnic origin with each of the above oral status measures. It was found that variations in ratios of decayed and of filled teeth were primarily due to economic status while variations in a number of missing teeth, oral hygiene levels and levels of gingival and periodontal diseases were primarily due to screenees' educational level. Ethnic group differences could be explained in part by differences among these groups in economic and and educational levels. There were no consistent ethnic patterns, however, and while some differences could be explained by controlling for education and economic status, others persisted.