A 640 by 480 Pixels Readout Circuit for IR Imaging

A readout circuit for a 640 × 480 pixels FPA (focal plane array) has been successfully designed, fabricated and tested. The circuit solution is based on a per pixel source-follower direct injection (SFDI) pre-amplifier. Signal multiplexing is performed in both X and Y direction. The pixel size is 25 m × 25m. The chip is optimized for a QWIP (quantum well infrared photodetector) operating at a temperature of 70 K. The circuit has been realized in a standard 0.8 m CMOS process.     

Spontaneous Desorption time-of-flight Mass Spectrometry (SDMS): Time correlated emission of electrons and negative ions in a constant electric field

A very simple time of flight mass spectrometer has been used to measure mass spectra for the negative ions of organic compounds in the mass range up to 3000 u. Desorbed ions were obtained by applying a constant negative voltage to a flat metallic surface, coated with a few micrograms of organic material. We show that electrons and negative ions are emitted simultaneously from the same point on the surface. Mass spectra obtained by this technique are compared to mass spectra for the same compounds, obtained with ²⁵²Cf fission fragment ionization.     

Atmospheric transport of polybrominated diphenyl ethers and polychlorinated biphenyls to the Baltic Sea

The atmospheric transport of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) was compared by measuring concentrations in air and deposition on an island located in the central basin of the Baltic Sea. Median sigmaPBDE and sigmaPCB concentrations (gaseous + particle) were 8.6 and 7.4 pg m(-3), respectively. Airborne PCBs were mainly found in the gaseous phase, while most of the PBDEs were detected on particles, which agrees with predicted particle/gas distributions. SigmaPBDE levels were dominated by the decabrominated BDE209 followed bythe tetrabrominated BDE47 and pentabrominated BDE99. BDE209 is a marker for the environmental distribution of the commercial deca-BDE formulation (>99.5% BDE209), whereas BDE47 and BDE99 are markers for the commercial penta-BDE mixture. General correlations between PBDEs and PCBs suggested similarities in sources and transport mechanism, while more detailed examination of the data identified notable behaviors and exceptions. Differences in regression slopes among tetra-, penta-, and decabrominated PBDEs may reflect different transport processes and the change in usage pattern. Tetra- and pentabrominated PBDEs may originate from secondary sources such as air surface exchange in a manner similar to that of the PCBs, while the deca-BDE209 formulation still has primary sources. The tribrominated BDE17 was also detected and is proposed to be a breakdown product due to atmospheric debromination processes. PBDEs had higher washout ratios than PCBs, explaining their higher concentrations compared to PCBs in precipitation (median of 6.0 and 0.5 ng L(-1) for sigmaBDE and sigmaPCB concentrations ("dissolved" + particle), respectively) than in air. The calculated yearly deposition of PBDEs and PCBs indicated that the atmospheric input of PBDEs to the Baltic Proper is currently exceeding that of the PCBs by a factor of 40, while that of the PCBs is decreasing.     

A setup for the coupling of a thin-layer electrochemical flow cell to electrospray mass spectrometry

A novel setup for the coupling of a commercially available thin-layer cell to electrospray mass spectrometry (ESI-MS) which allows the electrochemical reactions at the counter electrode to be straightforwardly separated from the flow into the mass spectrometer has been developed. In this way, interferences from reaction products formed at the counter electrode can be minimized. This reduces the risk of changes in the mass spectra as a result of electrochemical reactions in the solution. The described setup also enables the working electrode to be positioned close to the electrospray (ESI) emitter without the need for a grounding point or a long transfer line between the electrochemical cell and the electrospray emitter. By decoupling the electrochemical reactions in the flow cell and those in the electrospray emitter, improved facilities for studies of electrochemical reactions are obtained through a better control of the potential of the working electrode. The setup has been used to study the oxidation of a drug (Olsalazine), which previously has been found to involve chemical follow-up reactions. It is also demonstrated that uncharged thiols can be detected in ESI-MS after spontaneous adsorption on a gold working electrode, followed by oxidative desorption to yield sulfinates or sulfonates. This adsorption and potential-controlled desorption has been used for the preconcentration of micromolar concentrations of 1-hexanethiol as well as for desalting of solutions containing micromolar concentrations of thiols. The results indicate that the present on-line coupling of an electrochemical cell to ESI-MS provides promising possibilities for sample preconcentration, matrix exchange (including desalting), and ionization of neutral compounds, such as thiols.     

Protective actions in the late phase--intervention criteria and decision-making

Major countermeasures in the late phase of a nuclear or radiological accident where long-lived radionuclides have been dispersed in the environment are relocation/resettlement, foodstuff restrictions, agricultural countermeasures and clean-up of contaminated areas. There has essentially been a broad acceptance internationally of the principles for their introduction, but it has not been possible to reach an agreement for the purpose of defining a net benefit based upon the exact weighting to be attached to each of the attributes influencing the decision on intervention, e.g. socio-psychological attributes. Optimisation of protection, i.e. maximising the net benefit, is not a question of developing radiation protection philosophy to fully include socio-psychological factors but rather to include these factors--in parallel with the radiological protection factors--in cooperation between radiation protection experts and e.g. experts in social and psychological sciences under the responsibility of the decision-maker, who will take the final decision on the introduction of long-term countermeasures.     

How to make the structured design process work

The principles of implementing a model for project management and systems development are discussed. Consideration is given to the problems that arise in implementing structured techniques i.e. structured systems analysis and structured systems design, and a proven methodology is recommended, which gives the organization the basic foundation for success in systems development. It also contains a model for project management which includes a guide to the execution of quality and funding reviews throughout the life cycle.     

Plate equations for piezoelectrically actuated flexural mode ultrasound transducers

This paper considers variational methods to derive two-dimensional plate equations for piezoelectrically actuated flexural mode ultrasound transducers. In the absence of analytical expressions for the equivalent circuit parameters of a flexural mode transducer, it is difficult to calculate its optimal parameters and dimensions, and to choose suitable materials. The influence of coupling between flexural and extensional deformation, and coupling between the structure and the acoustic volume on the dynamic response of piezoelectrically actuated flexural mode transducer is analyzed using variational methods. Variational methods are applied to derive two-dimensional plate equations for the transducer, and to calculate the coupled electromechanical field variables. In these methods, the variations across the thickness direction vanish by using the stress resultants. Thus, two-dimensional plate equations for a stepwise laminated circular plate are obtained.     

Scientific Productivity and Group Size: A Bibliometric Analysis of Norwegian Microbiological Research

To analyse the relationship between research group size and scientific productivity within the highly cooperative research environment characteristic of contemporary biomedical science, an investigation of Norwegian Microbiology was undertaken. By an author-gated retrieval from ISI's database National Science Indicators on Diskette (NSIOD), of journal articles published by Norwegian scientists involved in microbiological research during the period 1992–1996, a total of 976 microbiological and 938 non-microbiological articles, by 3,486 authors, were obtained. Functional research groups were defined bibliometrically on the basis of co-authorship, yielding a total of 180 research groups varying in size from one author/one article to 180 authors/83 articles (all authors associated with a group during the whole five-year period were included, hence the large group size). Most of Norwegian microbiological research (73% of the microbiology articles) appears to be performed by specialist groups (with 70% of their production as microbiology), the remainder being published by groups with a broader biomedical research profile (who were responsible for 95% of the non-microbiological articles). The productivity (articles per capita) showed only moderate (Poisson-distributed) variability between groups, and was remarkably constant across all subfields, at about 0.1 article per author per year. No correlation between group size and productivity was found.