The wall shear stress produced by the normal impingement of a jet on a flat surface

A method for the theoretical determination of the wall shear stress under impinging jets of various congurations is presented. Axisymmetric and two-dimensional incompressible jets of a wide range of Reynolds numbers and jet heights are considered. Theoretical predictions from this approach are compared with available wall shear stress measurements. These data are critically evaluated based on the method of measurement and its applicability to the boundary layer under consideration. It was found that impingement-region wall shear stress measurements using the electrochemical method in submerged impinging liquid jets provide the greatest accuracy of any indirect method. A unique wall shear stress measurement technique, based on observing the removal of monosized spheres from well-characterized surfaces, was used to conrm the impinging jet analysis presented for gas jets. The technique was also used to determine an empirical relation describing the rise in wall shear stress due to compressibility eects in impinging high-velocity jets

Pathological and ecological host consequences of infection by an introduced fish parasite

The infection consequences of the introduced cestode fish parasite Bothriocephalus acheilognathi were studied in a cohort of wild, young-of-the-year common carp Cyprinus carpio that lacked co-evolution with the parasite. Within the cohort, parasite prevalence was 42% and parasite burdens were up to 12% body weight. Pathological changes within the intestinal tract of parasitized carp included distension of the gut wall, epithelial compression and degeneration, pressure necrosis and varied inflammatory changes. These were most pronounced in regions containing the largest proportion of mature proglottids. Although the body lengths of parasitized and non-parasitized fish were not significantly different, parasitized fish were of lower body condition and reduced weight compared to non-parasitized conspecifics. Stable isotope analysis (δ15N and δ13C) revealed trophic impacts associated with infection, particularly for δ15N where values for parasitized fish were significantly reduced as their parasite burden increased. In a controlled aquarium environment where the fish were fed ad libitum on an identical food source, there was no significant difference in values of δ15N and δ13C between parasitized and non-parasitized fish. The growth consequences remained, however, with parasitized fish growing significantly slower than non-parasitized fish, with their feeding rate (items s−1) also significantly lower. Thus, infection by an introduced parasite had multiple pathological, ecological and trophic impacts on a host with no experience of the parasite

Characterization of invasive and colonizing isolates of Streptococcus agalactiae in East African adults

Ninety-five colonizing isolates and 74 invasive isolates of Streptococcus agalactiae from Kenyan adults were characterized by using capsular serotyping and multilocus sequence typing. Twenty-two sequence types clustering into five clonal complexes were found. Data support the view that S. agalactiae isolates belonging to a limited number of clonal complexes are invasive in adults worldwide

Reducing conflict-related employee strain: The benefits of an internal locus of control and a problem-solving conflict management strategy

Workplace conflict is a potent stressor, but most previous research has focused on its effect on productivity and performance rather than on individual well-being. This paper examines the moderating roles of an individual's internal locus of control and a problem-solving conflict management strategy. In the cross-sectional study, among 774 health care workers in the Netherlands, employees' internal locus of control did moderate the relationship between experienced conflict at work and psychological strain, which was measured using a 13-item Dutch adaptation of the Occupational Stress Indicator. In addition, this moderation was mediated by the active conflict management strategy of problem solving; people with a more internal locus of control use a problem-solving conflict management strategy more often and, as a result, experience less psychological strain in cases of workplace conflict. Implications for conflict theory, for future research, and for practice are discussed

A comparison of particle mass spectrometers during the 1999 Atlanta Supersite Project

During the Atlanta Supersite Project, four particle mass spectrometers were operated together for the first time: NOAA's Particle Analysis by Laser Mass Spectrometer (PALMS), University of California at Riverside's Aerosol Time-of-Flight Mass Spectrometer (ATOFMS), University of Delaware's Rapid Single-Particle Mass Spectrometer II (RSMS-II), and Aerodyne's Aerosol Mass Spectrometer (AMS). Although these mass spectrometers are generally classified as similar instruments, they clearly have different characteristics due to their unique designs. One primary difference is related to the volatilization/ionization method: PALMS, ATOFMS, and RSMS-II utilize laser desorption/ionization, whereas particles in the AMS instrument are volatilized by impaction onto a heated surface with the resulting components ionized by electron impact. Thus mass spectral data from the AMS are representative of the ensemble of particles sampled, and those from the laser-based instruments are representative of individual particles. In addition, the AMS instrument cannot analyze refractory material such as soot, sodium chloride, and crustal elements, and some sulfate or water-rich particles may not always be analyzed with every laser-based instrument. A main difference among the laser-based mass spectrometers is that the RSMS-II instrument can obtain size-resolved single particle composition information for particles with aerodynamic diameters as small as 15 nm. The minimum sizes analyzed by ATOFMS and PALMS are 0.2 and about 0.35 μm, respectively, in aerodynamic diameter. Furthermore, PALMS, ATOFMS, and RSMS-II use different laser ionization conditions. Despite these differences the laser-based instruments found similar individual particle classifications, and their relative fractions among comparable sized particles from Atlanta were broadly consistent. Finally, the AMS measurements of the nitrate/sulfate mole ratio were highly correlated with composite measurements (r^2 = 0.93). In contrast, the PALMS nitrate/sulfate ion ratios were only moderately correlated (r^2 ∼ 0.7)

From papers to practices: district level priority setting processes and criteria for family planning, maternal, newborn and child health interventions in Tanzania

Contains fulltext : 97928.pdf (publisher's version ) (Open Access)ABSTRACT: BACKGROUND: Successful priority setting is increasingly known to be an important aspect in achieving better family planning, maternal, newborn and child health (FMNCH) outcomes in developing countries. However, far too little attention has been paid to capturing and analysing the priority setting processes and criteria for FMNCH at district level. This paper seeks to capture and analyse the priority setting processes and criteria for FMNCH at district level in Tanzania. Specifically, we assess the FMNCH actor's engagement and understanding, the criteria used in decision making and the way criteria are identified, the information or evidence and tools used to prioritize FMNCH interventions at district level in Tanzania. METHODS: We conducted an exploratory study mixing both qualitative and quantitative methods to capture and analyse the priority setting for FMNCH at district level, and identify the criteria for priority setting. We purposively sampled the participants to be included in the study. We collected the data using the nominal group technique (NGT), in-depth interviews (IDIs) with key informants and documentary review. We analysed the collected data using both content analysis for qualitative data and correlation analysis for quantitative data. RESULTS: We found a number of shortfalls in the district's priority setting processes and criteria which may lead to inefficient and unfair priority setting decisions in FMNCH. In addition, participants identified the priority setting criteria and established the perceived relative importance of the identified criteria. However, we noted differences exist in judging the relative importance attached to the criteria by different stakeholders in the districts. CONCLUSIONS: In Tanzania, FMNCH contents in both general development policies and sector policies are well articulated. However, the current priority setting process for FMNCH at district levels are wanting in several aspects rendering the priority setting process for FMNCH inefficient and unfair (or unsuccessful). To improve district level priority setting process for the FMNCH interventions, we recommend a fundamental revision of the current FMNCH interventions priority setting process. The improvement strategy should utilize rigorous research methods combining both normative and empirical methods to further analyze and correct past problems at the same time use the good practices to improve the current priority setting process for FMNCH interventions. The suggested improvements might give room for efficient and fair (or successful) priority setting process for FMNCH interventions