Atomic versus molecular Auger decay in CH2Cl2 and CD2Cl2 molecules.

Autoionization spectra of CH2Cl2 and CD2Cl2 molecules after Cl 2p excitation are studied. The two molecular and atomic Auger transitions are examined and assigned. The contribution of atomic Auger transitions is lower in the deuterated molecule. In addition, to support the presence of the ultrafast dissociation mechanism in the dichloromethane molecule, a series of high-level ab initio quantum mechanical calculations were performed at multiconfigurational self-consistent field (MCSCF) and multireference configuration interaction (MRCI) levels of theory. Minimum energy pathways for the dissociation of the dichloromethane molecule have been calculated by taking into account the spin-orbit splitting between the singlet and triplet transitions in the Cl 2p edge.

Structure and formation of highly luminescent protein-stabilized gold clusters.

Highly luminescent gold clusters simultaneously synthesized and stabilized by protein molecules represent a remarkable category of nanoscale materials with promising applications in bionanotechnology as sensors. Nevertheless, the atomic structure and luminescence mechanism of these gold clusters are still unknown after several years of developments. Herein, we report findings on the structure, luminescence and biomolecular self-assembly of gold clusters stabilized by the large globular protein, bovine serum albumin. We highlight the surprising identification of interlocked gold-thiolate rings as the main gold structural unit. Importantly, such gold clusters are in a rigidified state within the protein scaffold, offering an explanation for their highly luminescent character. Combined free-standing cluster synthesis (without protecting protein scaffold) with rigidifying and un-rigidifying experiments, were designed to further verify the luminescence mechanism and gold atomic structure within the protein. Finally, the biomolecular self-assembly process of the protein-stabilized gold clusters was elucidated by time-dependent X-ray absorption spectroscopy measurements and density functional theory calculations.

Fragmentation of Valence and Core-Shell (Cl 2p) Excited C2Cl4 Molecule.

The dynamics of the photofragmentation pathways of tetrachloroethylene with photon energies from 15 up to 250 eV encompassing the Cl 2p edge is presented. In order to distinguish the fragmentation channels, the ionic fragments were separated according to their mass-to-charge ratio, measured in coincidence with the photoelectrons, and collected as a function of the incident photon energy. Distinct minima or maxima are found in the partial ion yield in the region between 40 and 50 eV. These features are believed to be associated with the Cooper minimum which results from a molecular orbital with a strong atomic 3p subshell character. In the shallow core region, some fragmentation patterns are considered in terms of fast fragmentation of the C2Cl4 molecule, despite the heavy mass of its fragments. In the present case, the fast fragmentation is favored by the very strong antibonding character of the LUMO, understandable in the frame of the core equivalent model for halogen-containing molecules. In addition, ab initio calculations were performed to obtain states at the Cl 2p edge. Singlet and triplet states at the Cl 2p edge of the C2Cl4 molecule, corresponding to the Cl(2p → 9b1u*) and Cl(2p → 8b2u*) transitions, were calculated in order to form a basis set of molecular states from which the spin-orbit splitting can be inferred. Multiconfigurational self-consistent field (MCSCF) calculation followed by multireference configuration interaction (MRCI) was the method chosen to establish a set of singlet and triplet states at the 2p excitation edge in addition to the ground state.

Valence and Ionic Lowest-Lying Electronic States of Isobutyl Formate Studied by High-Resolution Vacuum Ultraviolet Photoabsorption, Photoelectron Spectroscopy, and Ab Initio Calculations.

The highest resolution vacuum ultraviolet photoabsorption spectrum of isobutyl formate, C5H10O2, yet reported is presented over the energy range 4.5-10.7 eV (275.5-118.0 nm) revealing several new spectral features. Valence and Rydberg transitions and their associated vibronic series observed in the photoabsorption spectrum have been assigned in accordance with new ab initio calculations of the vertical excitation energies and oscillator strengths. Calculations have also been carried out to determine the ionization energies and fine structure of the lowest ionic state of isobutyl formate and are compared with a newly recorded photoelectron spectrum (from 9.0 to 27.0 eV). The value of the first ionization energy was determined to be 10.508 eV (adiabatic) and 10.837 eV (vertical). New vibrational structure is observed in the first photoelectron band, predominantly resulting from C-O and C═O stretches of the molecule. The photoabsorption cross sections have been used to calculate the photolysis lifetime of isobutyl formate in the upper stratosphere (20-50 km), indicating that the hydroxyl radical processes will be the main loss process for isobutyl formate.

Observation of interference between two distinct autoionizing states in dissociative photoionization of H2.

Dissociative photoionization (DPI) of randomly oriented H(2) molecules has been studied using linearly polarized synchrotron radiation at selected photon energies of 31, 33, and 35 eV. Large amplitude oscillations in the photoelectron asymmetry parameter ß, as a function of electron energy, have been observed. The phase of these ß oscillations are in excellent agreement with the results of recent close coupling calculations [Fernández and Martín, New J. Phys. 11, 043020 (2009)]. We show that the oscillations are the signature of interferences between the 1Q(1) (1)Σ(u)(+) and 1Q(2) (1)Π(u) doubly excited states decaying at different internuclear distances. The oscillations thus provide information about the classical paths followed by the nuclei. The presence of such oscillations is predicted to be a general phenomenon in DPI.

X-ray spectroscopy studies on the surface structural characteristics and electronic properties of platinum nanoparticles.

The surface structural characteristics and electronic behavior of three platinum nanoparticle (NP) samples prepared with tertiary amine (Pt-TA), primary amine (Pt-PA), and thiol (Pt-SR) molecules were studied using Pt 4f, 5d, and S 2p x-ray photoelectron spectroscopy (XPS), Pt L(3)-edge x-ray absorption spectroscopy (XAS), and theoretical projected local density of states (l-DOS) calculations. Transmission electron microscopy and XPS composition analysis indicated that the three NPs were all very small (1-2 nm), the NP size decreasing in the order of Pt-TA>Pt-PA approximately Pt-SR. All the three samples showed a positive Pt 4f binding energy (BE) shift relative to that of the bulk, in the order of bulk

Reconciling concept and context: the dilemma of implementation in school-based health promotion.

The researchers used grounded theory methodology to study the implementation of a school-based alcohol and drug prevention project in secondary schools in British Columbia, Canada. Prevention workers (PWs) were responsible for working with school and community personnel in a collaborative process to develop, implement, and evaluate prevention strategies in the school using an adaptation of the Precede-Proceed Model for health promotion planning. Before they could begin to do this, PWs had to establish their credibility in the school. Once accepted, the focus of the PWs' work was to reconcile the goals, values, and philosophy of the project with those of the school. In doing so, PWs encountered many practical dilemmas. The challenges in resolving these dilemmas are presented, and the implications for policy and practice are discussed.

Hepatitis C virus antibody prevalence among injecting drug users at selected needle and syringe programs in Australia, 1995-1997. Collaboration of Australian NSPs.

OBJECTIVES: To describe point prevalence of HCV antibody and relevant risk behaviour among people who inject drugs and who attended selected needle and syringe programs throughout Australia in 1995, 1996 and 1997. DESIGN AND SETTING: Repeated cross-sectional surveys of one week's duration were carried out in 21, 20 and 23 needle and syringe program sites throughout Australia in 1995, 1996 and 1997, respectively. PARTICIPANTS: All clients attending participating sites during the designated survey week were asked to complete a self-administered questionnaire and provide a finger-prick blood sample for HCV antibody testing. MAIN OUTCOME MEASURES: Prevalence of HCV antibody. RESULTS: Survey response was 41% (n = 979) in 1995, 51% (n = 1463) in 1996 and 48% (n = 1699) in 1997. HCV prevalence declined significantly from 63% in 1995 to 51% in 1996 and 50% in 1997 (P < 0.001). Among respondents who reported injecting for less than three years, prevalence declined from 22% in 1995 to 13% in 1996 and 1997 (P < 0.001). Reported use of needles and syringes after someone else in the previous month declined from 31% in 1995 and 28% in 1996 to 15% in 1997 (P < 0.001). CONCLUSIONS: Despite an apparent decline in HCV prevalence, carriage rates of HCV antibody remain high.

Reporting of occupational exposures to blood-borne pathogens in Australian teaching hospitals.

OBJECTIVE: To describe the reporting of occupational exposures to blood and body fluids in Australian teaching hospitals. DESIGN: Survey by questionnaire of the major teaching hospitals in Australia, December 1992. RESULTS: Completed questionnaires were received from 88% of the 69 teaching hospitals in Australia. All responding hospital reported an established procedure for reporting and managing occupational exposures to blood and body fluids and 82% indicated willingness to contribute data to a national monitoring project. Information concerning the actual incident was recorded by all hospitals and two-thirds of hospitals had forms which specifically detailed exposures history. Patient and healthcare worker risk factors for HIV were recorded less frequently. but in 87% of hospitals blood tests were performed on both the staff member and source patient. Among 87 026 equivalent full time staff employed by the responding hospitals, 5803 injuries were reported in 1991. The median number of reported injuries as a percentage of equivalent full time staff was 7%. Estimates of non-reporting ranged from 5% to 70% (median 25%). Prophylactic zidovudine was prescribed for 50 staff from 21 hospitals in 1991. CONCLUSIONS: All Australian teaching hospitals have an established procedure for documenting occupational exposure to blood and body fluids. Although there is limited standardisation at a national level, the information already collected and the willingness to participate indicated by a large number of teaching hospitals are sufficient for a national surveillance mechanism to be established.

Antenatal HIV antibody testing in Australia.

OBJECTIVE: To evaluate the role of voluntary antenatal testing in HIV surveillance and prevention by examining antenatal HIV antibody testing practice and policy in Australia. DESIGN: Cross-sectional study using a self-administered questionnaire. SUBJECTS AND SETTING: Specialist obstetricians and gynaecologists and general practitioners (GPs) affiliated with the Royal Australian College of Obstetricians and Gynaecologists and Australian public hospital antenatal clinics, August-November 1992. MAIN OUTCOME MEASURES: The percentage of public hospital antenatal clinics and specialist and GP obstetricians in Australia who tested pregnant women for HIV antibody as part of their antenatal care, and the proportion of pregnant women in Australia who had an antenatal HIV antibody test in the 1991-92 financial year. RESULTS: Questionnaires concerning antenatal HIV antibody testing were completed by 90% (993/1108) of specialists, 87% (2134/2461) of GPs and 93% (215/230) of public hospitals surveyed. Of the 706 specialists and 1503 GPs who reported that they were currently engaged in obstetric care, approximately 60% (430/706) and 935/1503, respectively) offered antenatal HIV testing either to all pregnant women or to selected groups at risk. There were significant differences in testing patterns between States and Territories. For the 95 public hospitals with antenatal clinics, 81% (77) offered the HIV antibody test to all or selected groups of pregnant women; these percentages did not differ significantly between States and Territories. It was estimated that 25% of pregnant women seen by specialists, 29% seen by GPs and 9% seen in public hospital clinics were tested for HIV antibody as part of their antenatal care in 1991-92. CONCLUSIONS: In Australia approximately one in five pregnant women were tested for HIV antibody as part of their antenatal care in 1991-92. Voluntary HIV testing in pregnancy may provide unrepresentative data for measuring the prevalence of HIV infection in pregnant women.

An outbreak of a penicillin-sensitive strain of gonorrhoea in Sydney men.

OBJECTIVE: To describe an outbreak of gonorrhoea caused by penicillin sensitive Wild type 1B2-Wt/1B2(FS), in homosexual men in Sydney. DESIGN AND SETTING: The study sample comprised all gonococcal isolates referred to the Gonococcal Reference Laboratory (GRL), New South Wales, Australia between 1 January 1990 and 30 June 1992. Demographic data on Wt/1B2(FS) were sought by review of all request forms accompanying specimens to the GRL. Detailed review was undertaken of the clinical records of all men with gonorrhoea which had been differentiated by auxotype and serotype (A/S) from two large STD clinics in Sydney. MEASUREMENTS AND MAIN RESULTS: The first isolation of Wt/1B2(FS) was made in April 1990 and by the end of July 1992, 140 such isolates were identified in 131 patients. The male:female ratio was 130:1 suggesting male homosexual transmission, which was confirmed in 55 of 57 evaluable cases. There was a higher proportion of pharyngeal and anal infections among Wt/1B2(FS) isolates compared with all other male gonorrhoea. Demographic information showed that 60% of men with Wt/1B2(FS) were under the age of 30, and 80% lived in Central or Eastern Sydney. CONCLUSIONS: An outbreak of a penicillin sensitive strain of gonorrhoea has occurred in Sydney, primarily among gay men living in the inner city. The extent to which the outbreak represents an increase in the risk of HIV transmission is unclear.

Hepatitis B prenatal screening survey, Nova Scotia, 1990-1991.

We conducted a study in which 5,754 pregnant women who delivered at the Grace Maternity Hospital in Halifax were screened for HBsAg. There were five who were found to be seropositive for the first time (a screening yield for seropositivity of 8.7/10,000). Overall six were seropositive for a prevalence rate of 10.4/10,000. These rates are above the 6.0/10,000 level at which routine prenatal screening is considered to be cost-effective. Screening based upon risk factors would have identified only two of the five women who were found for the first time to be HBsAg seropositive. Based upon the results of this study, we recommend that routine screening for HBsAg be performed on all prenatal women in Nova Scotia.

Enhanced detection of respiratory viruses using the shell vial technique and monoclonal antibodies.

The shell vial technique using A549 and MDCK cells, coupled with the use of Bartels respiratory viral monoclonal antibodies, was evaluated initially for the detection of 28 previously isolated respiratory viruses. All viruses were recovered and correctly identified. The shell vial-monoclonal antibody technique was then evaluated for virus isolation from 338 respiratory specimens and compared with the conventional tube method. Both methods gave rise to a total of 83 virus isolates. Of these isolates, 68 (20.1%) were isolated and identified by the shell vial-monoclonal method; 60 (17.8%) were culture-positive by the conventional tube method; forty-five (13.3%) were positive by both methods. The shell vial-monoclonal antibody method yielded 12 isolates of influenza A, two isolates of parainfluenza type 3 and one each of parainfluenza types 1 and 3, which were missed by the conventional tube method, indicating the superior sensitivity and specificity of the shell vial-monoclonal antibody method (Chi-square analysis, P = 0.001) for the detection of these viruses. Of the 50 RSV isolates, 29 were detected by both methods and there were 21 discrepancies between the two methods. The shell vial-monoclonal antibody method also improved the turn-around time for the respiratory virus groups.

A novel approach to enterovirus typing.

A novel method was developed for typing enteroviruses producing cytopathic effect. Monolayers of primary or secondary rhesus monkey kidney cells were prepared and covered with an agarose overlay. Wells were formed in the agarose, the well bottom being optimally determined to be 3 mm from the monolayer and homotypic enterovirus antiserum, intersecting antiserum pool or antiserum-diluent as control was added. After 2 h at 37 degrees C, the test virus isolate was added to each well. Cultures were incubated at 37 degrees C and were examined daily until cytopathic effect was readily observed in the control well. Monolayers were fixed and stained for macroscopic reading. Enterovirus identity based on the inhibition of cytopathic effect was confirmed with a conventional micro-neutralization method. In all, 51 enterovirus isolates were typed. Included were 21 polioviruses, 9 coxsackieviruses and 21 echoviruses, all of which were correctly identified. This method takes advantage of the ability of enterovirus and antibody to diffuse through agarose. It is simple to perform. It does not require preliminary titration of the test virus isolate and tolerates 1,000 fold fluctuations in virus concentration, thereby offering laboratories a more rapid and efficient means of typing enteroviruses.

Toward the development of self-help health behaviour change programs: weight loss by correspondence.

The goal of this study was to evaluate a correspondence weight control program, and to assess the impact of three program elements (weekly homework, interim weigh-ins, and participation deposits) individually and in combination. All treated participants received 15 weekly standard lessons by mail. Three program features were varied factorially: a) homework assignments, b) interim weigh-ins and c) a deposit refunded contingent on returning homework and/or attending interim weigh-ins. Participants were assigned randomly to active treatment conditions or a delayed treatment control group. Among treated males (N = 14), initial average weight loss and BMI reduction were 9.6 kg and 3.1 respectively; average net weight loss and BMI reduction at one year follow-up were 5.8 kg and 1.9 respectively. Among treated females (N = 128), initial average weight loss and BMI reduction were 3.1 kg and 1.2 respectively; average net weight loss and BMI reduction at one year were 2.3 kg and .88 respectively. Women in all treated groups, except lessons only, showed a greater BMI reduction than untreated controls at the end of treatment. Women in conditions including both homework and interim weigh-ins had greater initial BMI reductions (M = 1.6) than those who received lessons only (M = .76). At one year, net BMI reductions were comparable across all treated groups. Of the 42 women initially registered in conditions that included both homework and weigh-ins, 12 who denied joining other programs lost at least 4.5 kg (M = 7.1) during treatment, and 7 had a net loss of at least 4.5 kg (M = 8.0) at one year without apparent involvement in any other program.

A synthetic based medium for the isolation of Listeria monocytogenes.

We have compared two media (Tryptone Soya Nalidixic Acid Agar and Tryptone Soya Gum Base Nalidixic Acid Medium) for the isolation of L. monocytogenes from pathological and environmental specimens. These media were used in conjunction with Henry's Oblique Light System. We found that the gum based medium gave the better results. The medium is uniformly transparent, partially suppressive to unwanted organisms and allows colonies of Listeria to be readily identified.

Effect of treadmill exercise on food intake and body weight in lean and obese rats.

Body weight and food intake of lean and obese, male and female Osborne-Mendel rats following treadmill exercise were compared. Rats were assigned, separately by sex, to one of three diet groups; Group 1 was fed a low fat (10%) diet throughout the study, Group 2 was fed a high fat (55%) diet for 16 weeks and then switched to the low fat diet 1 week prior to exercise, and Group 3 was fed the high fat diet throughout the study. To control for differences in work output between the leanest and heaviest animals, exercise intensity was adjusted across groups such that all exercised rats had equivalent energy expenditure. After a 3 day training period, the exercise was successively increased over 8 days until a work output of 374.9J was reached. Relative to their respective controls, obese exercised males showed a reduction in body weight but no change in food intake. In contrast, exercised females showed no change in body weight or food intake, regardless of dietary condition.

Evaluation of cerebrospinal fluid lactic acid levels as an aid in differential diagnosis of bacterial and viral meningitis in adults.

The level of lactic acid in cerebrospinal fluid has been suggested as a useful diagnostic parameter to differentiate between bacterial and viral meningitis, especially in patients partially treated before admission to hospital. A concentration of greater than or equal to 35 mg/dl, determined by either gas-liquid chromatography or an enzymatic method, has been considered in several studies to provide definite evidence of meningitis of bacterial origin, whereas a lower level indicates no bacterial involvement. Over the past 18 months, we have analyzed by the enzymatic method the lactate level in 493 spinal fluids submitted from 434 adult patients with various conditions involving the central nervous system. Fifty fluids had a lactate level of greater than 35 mg/dl, of which 19 were cases of infective meningitis of varying etiology. The 435 specimens with lactate levels within the range considered normal included three cases of infective meningitis, of which two were cryptococcal and one was bacterial. In this adult study, the lactate level in the cerebrospinal fluid did not provide unequivocal evidence of bacterial infection and did not provide assistance to any greater degree than the standard parameters of leukocyte count, protein, and glucose contents in the differential diagnosis of bacterial meningitis from that of any other etiology.