Relationship between soil lead and airborne lead concentrations at Springfield, Missouri, USA

This study tests whether lead deposited to soil from automobiles during past years in a medium-sized US city (population 150,000) may present a current health risk. It examines the relationship between current soil lead concentrations at nine locations within the city of Springfield, Missouri, and airborne lead levels measured at the same locations during years (1975-1981) when lead emissions from automobiles were much greater than at present. A strong, significant correlation is found between soil and airborne lead levels at eight of the sites (r = 0.91, P < 0.005 for soil lead vs. 1979 airborne lead), in low-traffic areas as well as in areas adjacent to heavy traffic flow. Residual lead concentrations in these soils are relatively low, even for the high-traffic sites, as expected for a medium sized city.     

Internet telephony signaling

The term “multimedia session” refers to the integration of data coming from various sources, such as sound, video and text, within a computer application. Telephony over the Internet is among the more exciting current developments. The signaling of a telephone call consists of the set of messages and procedures used to establish a connection, to request changes in communication bandwidth, to obtain the message status for the end points participating in the conversation, and to close the link. At present there exist two competing signaling protocols for Internet telephony, viz., the H.323 protocol sponsored by the ITU and the Session Invitation Protocol (SIP) sponsored by the IETF. Each of them supplies its own signaling mechanisms.

In this paper, these two protocols in terms of their main functionalities are compared. Based on the results of this comparison, a Client/Server architecture for the development of an application that supports a basic SIP implementation, as well as the formulation of requests allowing the establishment and the disconnection of communications between a number of users in a multimedia session are then defined.     

Does safety climate predict safety performance in Italy and the USA? Cross-cultural validation of a theoretical model of safety climate

Previous studies have acknowledged the relevance of assessing the measurement equivalence of safety related measures across different groups, and demonstrating whether the existence of disparities in safety perceptions might impair direct group comparisons. The Griffin and Neal (2000) model of safety climate, and the accompanying measure (Neal et al. [NGH], 2000), are both widely cited and utilized. Yet neither the model in its entirety nor the measure have been previously validated across different national contexts. The current study is the first to examine the NGH measurement equivalence by testing whether their model of safety climate predicting safety performance is tenable in both English speaking and non-English speaking countries. The study involved 616 employees from 21 organizations in the US, and 738 employees from 20 organizations in Italy. A multi-group confirmatory factor analytic approach was used to assess the equivalence of the measures across the two countries. Similarly, the structural model of relations among the NGH variables was examined in order to demonstrate its cross-country invariance. Results substantially support strict invariance across groups for the NGH safety scales. Moreover, the invariance across countries is also demonstrated for the effects of safety climate on safety knowledge and motivation, which in turn positively relate to both compliance and participation. Our findings have relevant theoretical implications by establishing measurement and relational equivalence of the NGH model. Practical implications are discussed for managers and practitioners dealing with multi-national organizational contexts. Future research should continue to investigate potential differences in safety related perceptions across additional non-English speaking countries.     

Heavy metal distribution in some French forest soils: evidence for atmospheric contamination

This study is one of very few dealing with the distribution and the origin of heavy metals in French soils from a priori non-polluted forest areas. The abundance of heavy metals measured in these soils decreases as follows: Cr>Zn>Pb>Ni>Cu>Co>Cd. Total concentrations of Pb, Cr and Ni in some soils exceed the European thresholds for non-polluted soils and even the French association of normalization critical values for sludge spreading. The lowest heavy metal contents are observed in acid soils while the highest concentrations are in the calcaric cambisol and in the mollic andosol, which is rather scarce as compared with the other French forest soils. With the exception of the podzol, Cr and Ni concentrations increase with depth in all soil profiles. The distribution pattern of Co, Cu, Zn depends on the soil characteristics. In some acid soils, however, Cu and Zn decrease with depth. Pb and Cd are accumulated in the upper soil horizons. Heavy metals accumulate in deep soil horizons in relation to important clay content in the dystric planosol and stagnic luvisol. The concentration of each heavy metal is always controlled by different parameters (soil pH, iron and aluminum oxide content, clay content, organic matter and cation exchange capacity), which are heavy metal specific. This study highlights the metal-trapping character of andosol and calcaric soil, the weak heavy metal retention in acid soils, the leaching and trapping character in leached clayed soils, and the migration of heavy metals in the podzol. Pb and Cr concentrations indicate a significant enrichment in surface horizons from various soils in areas which receive significant acid atmospheric pollution. Particularly, the highest Pb content is observed in a soil located in the N-NE part of France. Lead isotope ratios measured in the cambic podzol and the calcaric cambisol, exhibit the importance of the anthropogenic sources and particularly the influence of global atmospheric inputs from leaded gasoline compared to regional and local industrial emissions. The anthropogenic Pb contribution is estimated to 83, 30 and 11%, respectively, for surface, intermediate and deep horizons of the cambic podzol located in the northern part of France, and to 68% in surface horizon of the calcaric cambisol located in the Alps.     

ST segment changes in the ECG. Anesthesia induction with propofol, etomidate or midazolam in patients with coronary heart disease

Induction of anaesthesia with propofol and fentanyl can lead to marked reductions in mean arterial pressure (MAP) and heart rate (HR). Thus, the application of propofol in patients with severely reduced coronary artery perfusion is controversial. METHODS. The study group consisted of 60 patients undergoing coronary artery bypass grafting (CABG). Anaesthesia was induced over 30 s with propofol (P 1.5 mg/kg), etomidate (E 0.3 mg/kg), or midazolam (M 0.15 mg/kg) following a bolus dose of fentanyl (5 micrograms/kg). Vecuronium was used as a muscle relaxant. During induction we continuously measured MAP and HR and recorded the occurrence of myocardial ischaemia using an automatic ST-segment analyser (Marquette 7010). ST-segment deviations of more than 1 mm in leads II and V5 were interpreted as significant signs of myocardial ischaemia. RESULTS. All groups showed reductions in MAP and HR on induction that were marked in the P group. Intubation caused elevation of MAP and HR to pre-induction levels (HR: all groups) or slightly above (MAP: E, M). Four patients in the P group and 3 in each other group showed significant ST-segment deviation prior to induction. In the P group these deviations disappeared in 2 patients after injection while they remained unchanged in the M group. In the E group injection had no effect on the ischaemic ECG changes but produced another case of significant ST-segment deviation. Laryngoscopy and intubation produced no further significant ST-segment deviation in either group. DISCUSSION. Induction is a critical phase of anaesthesia, especially in patients with limited coronary reserve. Induction agents should alleviate the stress response while causing minimal haemodynamic changes. Despite marked reductions in MAP in the P group, the number of patients with ischaemic ECG changes was cut by half. Their number was unchanged or even raised in the other groups. After application of P, with an alleged reduction of coronary perfusion, a compensational reduction in myocardial oxygen consumption may occur.     

A flexible brand choice model based on neural net methodology A comparison to the linear utility multinomial logit model and its latent class extension

Brand choice models as a rule have a linear (deterministic) utility function, i.e. they conceive utility as linear combination of predictors like price, sales promotion variables, brand name and other product attributes. To discover nonlinear effects on brands' utilities in a flexible way we specify deterministic utility by means of a certain type of neural net. This feedforward multilayer perceptron is able to approximate any continuous multivariate function and its derivatives with the desired level of precision. In an empirical study the neural net based choice model leads to better out-of-sample results than homogeneous and heterogeneous versions of linear utility MNL models. On the other hand the latent class variant of the linear utility MNL model attains better fit values for estimation data than the neural net model. The neural net approach implies different choice elasticities for most predictors and identifies nonlinear effects (like interaction effects, thresholds, saturation effects). Received: November 3, 2000 / Accepted: March 7, 2002     

Noninvasive tracking of patient's head movements during computer-assisted intranasal microscopic surgery

A noninvasive system designed for patient tracking during image-guided intranasal sinus surgery is described. It is based on optical digitizing with a custom-made registration and reference system, locatable surgical instruments, and a self-localizing operating microscope. Experimental and clinical results reveal a high degree of accuracy for the system. A mean spatial error of 0.82 +/- 0.31 mm was determined for repositioning of the reference system in a plastic model of the skull. For the positioning of the microscope, a mean error of 2.3 +/- 0.83 mm was calculated. Measurements of repositioning accuracy in 24 patients who received surgery for various sinus diseases had a mean spatial error of 1.56 +/- 0.76 mm. The 95% error interval for locating intranasal structures using the surgical instrument was 2.05 mm, and it was 4.92 mm using the microscope. These results suggest that the use of our noninvasive registration and reference system may be effective, accurate, and useful for noninvasive tracking of patient movements in computer-assisted intranasal surgery.     

Use of a mass-thickness marker to estimate systematic errors and statistical noise in the detection of phosphorus by electron spectroscopic imaging

The element signal obtained from electron-energy-filtered micrographs depends on the systematic error in calculating the background and on the noise in the background-corrected image. Both systematic error and statistical fluctuation of the background can be assessed experimentally with a specimen that combines the element-containing feature with a mass-thickness marker. The approach is described for the mapping of phosphorus in turnip yellow mosaic viruses prepared on a supporting carbon film of variable thickness. The thickness modulations are produced by the additional deposition of heat-evaporated carbon through a second grid used as a mask. The three-window power-law method and the two-window difference method are compared. With the three-window power-law method, the mass-thickness modulations of the marker are still visible in the map, indicating a systematic error for the calculated background. In addition, the intensity profile over the area of the thick carbon film is broader than in the map corrected by the two-window method, indicating a higher level of noise. With the two-window difference method, mass-thickness contrast was practically eliminated due to an improved protocol that uses the mass-thickness marker to calculate the scaling factor: instead of scaling the grey-level of a single background feature, the pre-edge image is scaled to the contrast of the marker area in the image acquired at the element-specific energy loss.     

Diagnostic value of otoacoustic emissions. 1

Analogues of the potent and selective 5-HT1A ligand, WAY 100635, were synthesized and examined as potential candidates for imaging 5-HT1A receptors by positron emission tomography (PET). Several of the analogues displayed nanomolar affinity for the 5-HT1A receptor, comparable to WAY 100635. Three of these were examined in a model of human liver metabolism vis-à-vis WAY 100635. All showed a markedly lower propensity for amide hydrolysis than WAY 100635. Radiolabelling of these three potential PET radiotracers with carbon-11 was readily achieved from [11C]-iodomethane, and the newly synthesized radioligands were tested in vivo in rats for binding to 5-HT1A receptors. Whereas two of the ligands failed to bind to 5-HT1A receptors in vivo, one was successful. The latter, [11C]-7 [4-(2'-methoxyphenyl)-1-[2'-[N-(2'-pyridinyl)-2-bicyclo[2.2.2]octanec arboxamido]ethyl]-piperazine], showed good brain penetration, hippocampal:cerebellar ratios of 10:1 at 45 min postinjection. Blocking studies with a variety of drugs demonstrated that the binding of [11C]-7 in vivo was selective for 5-HT1A receptors. [11C]-7 is a promising candidate as a ligand for imaging 5-HT1A receptors by PET.     

Nucleation of polyvinyl alcohol crystallization by single-walled carbon nanotubes

Non-isothermal crystallization experiments were performed on poly(vinyl alcohol) mixed with single-walled carbon nanotubes. Non-isothermal crystallization experiments showed that nanotubes nucleate crystallinity at weight fractions as low as 0.1%. An Ozawa model was applied to the non-isothermal crystallization data, and this approach confirmed the results deduced from the qualitative examination of the data: there was a clear difference in crystallization kinetics for the 0.1 and 1% sample vs. the sample without nanotubes. Nanotubes were also found to promote the thermal degradation of poly(vinyl alcohol).