Conversion between standard and low-alpha lead in solder bumping production lines

Soft-errors caused by lead in solder-bumping have been a concern for many years. The problem is of special concern for high-density interconnection applications requiring solder to be placed directly over active circuitry. In that situation, alpha particles emitted by radioactive lead cause soft-errors with no possibility of shielding circuitry. For optimal cost-effectiveness, though, not all solder bumped wafers require low-alpha lead. MCNC has developed a solder bumping facility with both a research branch at MCNC and a full-scale production facility at its spin-off, Unitive Electronics Inc. We present results here of our work in incorporating low-alpha lead as part of our solder bumping process. We describe the amount of cross-contamination measured when alternating plating baths of regular lead and low-alpha lead.     

A Comparison of the Performance and Stability of ZnO-TFTs With Silicon Dioxide and Nitride as Gate Insulators

The performance and stability of thin-film transistors with zinc oxide as the channel layer are investigated using gate bias stress. It is found that the effective channel mobility, ON/OFF ratio, and subthreshold slope of the devices that incorporate SiN are superior to those with SiO₂ as the dielectric. The application of positive and negative stress results in the device transfer characteristics shifting in positive and negative directions, respectively. The devices also demonstrate a logarithmic time-dependent threshold voltage shift suggestive of charge trapping within the band gap and the band tails responsible for the deterioration of device parameters. It is postulated that this device instability is partly a consequence of the lattice mismatch at the channel/insulator interface. All stressed devices recover to near-original characteristics after a short period at room temperature without the need for any thermal or bias annealing.     

Wind resource assessment of an area using short term data correlated to a long term data set

A method of estimating the annual wind energy potential of a selected site using short term measurements related to one year’s recorded wind data at another reference site is presented. The proposed method utilizes the 1-year measured wind speed of one site to extrapolate the annual wind speed at a new site, using an artificial neural network (ANN). In this study, concurrent measurements from target and reference sites over periods of 1-month and 2-month were used to “train” the ANN. Topographical details or other meteorological data are not required for this approach. After derivation of the simulated wind speed time series for the target site, its mean value and its corresponding Weibull distribution parameters are calculated. The derived Weibull distribution of the simulated wind speed is used to make an assessment of the annual wind energy resource in the new area with respect to a particular wind turbine model. Three pairs of measuring stations in the southwest of Ireland were examined, where the wind potential is high and technically exploitable. Analysis of the measurements showed a reasonable cross-correlation coefficient of the wind speed between the sites. Results indicate that with this method, only a short time period of wind data acquisition in a new area might provide the information required for a satisfactory assessment of the annual wind energy resource. To evaluate the accuracy of the method, simulation results of the 1-month and 2-month training periods are compared to the corresponding actual values recorded at the sites. Also, a comparison with the results of a commercial wind energy assessment software package is presented showing similar results.     

Strain gauge plethysmography and Doppler ultrasound in the measurement of limb blood flow

The maintenance of adequate oxygen delivery (DO2) and tissue uptake (VO2) has become central dogma in the management of the critically ill. However, these parameters are derived using gas tensions measured in mixed venous blood and may not reflect changes in regional blood flow. Therefore, it has become necessary to provide estimates of blood flow to specific organs and to evaluate the most adequate techniques available. In order to define the best means of assessing blood flow to the lower limb noninvasively in normal subjects, measurements of superficial femoral arterial blood flow using Doppler ultrasound (DU) and strain gauge plethysmography (SGP) were compared in 10 normal volunteers at rest and during exercise. To evaluate the effect of strain gauge positioning, results of measurements made under four different combinations of cuff/strain gauge placement were compared in 15 other volunteers. The correlation of the limb blood flow obtained using the two methods at rest and exercise was 0.57 and 0.62 and the limits of agreement (d +/- 2SD) were 0.40 +/- 2.49 and -0.86 +/- 5.22 ml 100 ml-1 tissue min-1 at rest and on exercise, respectively. Results obtained using SGP were more reproducible (Coef. repeat. 0.45 vs. 0.94 ml 100 ml-1 tissue min-1, for SGP and DU, respectively). The various combinations of cuff/strain gauge positioning showed a tendency to over-read when the latter was placed on the thigh, but were not significantly different (P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Relationship between self-report and log data estimates of information system usage

Self-report estimates of frequency and duration of computer use are used extensively in research related to computer and information systems acceptance. Despite concerns that self-report estimates are inferior to computer log data there is a paucity of research investigating the relationship between self-report and log data measures of computer use. The present study compared self-report estimates and six months of electronic log data for 62 health care workers using a new Community Services Information System. There were moderate to strong correlations between the self-report and electronic log estimates of frequency and duration of system use. Self-report estimates were relatively accurate in that they were quite similar in magnitude to log data values. The merits of combinations of frequency and duration data (composites) were also assessed.     

JOY: protein sequence-structure representation and analysis

MOTIVATION: JOY is a program to annotate protein sequence alignments with three-dimensional (3D) structural features. It was developed to display 3D structural information in a sequence alignment and to help understand the conservation of amino acids in their specific local environments. RESULTS:: The JOY representation now constitutes an essential part of the two databases of protein structure alignments: HOMSTRAD (http://www-cryst.bioc.cam.ac.uk/homstrad ) and CAMPASS (http://www-cryst.bioc.cam.ac. uk/campass). It has also been successfully used for identifying distant evolutionary relationships. AVAILABILITY: The program can be obtained via anonymous ftp from torsa.bioc.cam.ac.uk from the directory /pub/joy/. The address for the JOY server is http://www-cryst.bioc.cam.ac.uk/cgi-bin/joy.cgi. CONTACT: kenji@cryst.bioc.cam.ac.uk     

Preparation and X-ray characterization of CsAlSiO4

A systematic study of the preparation of CsAlSiO₄ using various cesium oxide, alumina, and silica sources and a typical set of firing conditions was performed. The objective was to determine effective methods of preparing phase-pure CsAlSiO₄. The reaction of Cs₂CO₃ with metakaolin at 600°C (decomposition and calcining), 850°C (prefiring) and 1050°C (crystallization) produced the only phase-pure CsAlSiO₄ obtained by these methods. None of the eighteen sets of starting materials yielded a phase-pure CsAlSiO₄ in the 1100°C and 1200°C firings. CsAlSiO₄ was determined to be isomorphous with RbAlSiO₄ as reported by Klaska and Jarchow (1). CsAlSiO₄ is orthorhombic with lattice parameters of $\text{a}{}_{\mathrm{<mtext>o</mtext>}}\text{= 8.907 (2)}\text{A}\text{?}\text{,}\text{b}{}_{\mathrm{o}}\text{= 9.435(1)}\text{A}\text{?}\text{,}\text{and}\text{c}{}_{\mathrm{<mtext>o</mtext>}}\text{= 5.435(1)}\text{A}\text{?}$. The space group is Pna2₁, with Z = 4. Single crystals of CsAlSiO₄ were grown hydrothermally from a lCs₂O:1Al₂O₃:2SiO₂ gel in a 3M CsOH solution. The reaction conditions were 770°C and 11, 700 psi. The crystal habit of CsAlSiO₄ is needle-like.     

Nursing student compliance to standards for blood pressure measurement

In conclusion, no individual student complied with every step of the recommended procedure. In fact, 95% failed to comply with some specific steps that are unique to the AHA standards and that experts consider critical to accurate blood pressure measurement. Response to the questionnaire revealed that factors of logistics and attitudes of others influence student compliance or at least make the situation less conducive to adhering to the AHA standards. An additional interesting finding from the questionnaire was that while students may not have complied entirely with the AHA standards, they believed the procedure to be reasonable and to provide an accurate reading of blood pressure.     

Acute skin GVHD following syngeneic BMT for CLL

A 41-year-old woman received a syngeneic BMT for CLL and subsequently developed acute skin GVHD. Transfusion-related allogeneic GVHD was excluded on the basis of an unchanged HLA type in circulating lymphocytes. Short tandem repeat PCR was used to confirm syngeneicity between donor and recipient. The patient had a personal and family history of autoimmune disease which may have made her particularly susceptible to development of syngeneic GVHD. The distinction between allogeneic and syngeneic or autologous GVHD is important because of therapeutic implications.     

Occupational differences in computer-related anxiety: implications for the implementation of a computerized patient management information system

The present investigation was concerned with the implementation of an information system within a health care setting. A large number of staff required training on a new patient management information system (MIS). The aim of this study was to assess occupational differences on a number of psychological variables associated with MIS success. Computer anxiety was of primary concern due to its relationship to avoidance of computers. A total of 175 questionnaires were distributed, with 103 questionnaires being completed and returned for analysis (61.1%). It was found that clerical/administrative staff had significantly higher self-efficacy regarding computer use and more experience with computers. The nursing group experienced significantly more, computer anxiety, negative attitudes, and negative expectations than the clerical group. Self-efficacy was found to be the best predictor of computer related anxiety. The results have implications for MIS implementation strategies particularly in the areas of training and resource allocation.