Transfer of Salmonella and Campylobacter from stainless steel to romaine lettuce

The degree of transfer of Campylobacter jejuni and Salmonella enterica serovar Typhimurium was evaluated from a stainless steel contact surface to a ready-to-eat food (lettuce). Stainless steel coupons (25 cm2) were inoculated with a 20-microl drop of either C. jejuni or Salmonella Typhimurium to provide an inoculum level of approximately 10(6) CFU/28 mm2. Wet and dry lettuce (Lactuca sativa var. longifolia) pieces (9 cm2) were placed onto the inoculated stainless steel surface for 10 s after the designated inoculum drying time (0 to 80 min for C. jejuni; 0 to 120 min for Salmonella Typhimurium), which was followed by the recovery and enumeration of transferred pathogens (lettuce) and residual surface pathogens (stainless steel coupons). For transfers of Salmonella Typhimurium to dry lettuce, there was an increase from 36 to 66% in the percent transfer of the initial inoculum load during the first 60 min of sampling and then a precipitous drop from 66 to 6% in percent transfer. The transfer of Salmonella Typhimurium to wet lettuce ranged from 23 to 31%, with no statistically significant difference between recoveries over the entire 120-min sampling period. For C. jejuni, the mean percent transfer ranged from 16 to 38% for dry lettuce and from 15 to 27% for wet lettuce during the 80-min sampling period. The results of this study indicate that relatively high numbers of bacteria may be transferred to a food even 1 to 2 h after surface contamination. These findings can be used to support future projects aimed at estimating the degree of risk associated with poor handling practices of ready-to-eat foods.     

Meat quality in male fallow deer (Dama dama): effects of age and supplementary feeding

Thirty-two male fallow deer, half 18- and half 30-month-old, were slaughtered after a 4-month feeding trial on pasture alone or with daily supplement of 500 g (dry matter) concentrate/head (eight each 18- and 30-month-old). Neither diet nor age produced significant effects on M. longissimus thoracis et lumborum (LM) and on M. semimembranosus (SM) pH and colour. Meat texture properties (Warner-Bratzler-WB Shear Force and compression), water loss and collagen content were unaffected by diet, while the older deer had higher LM WB peak force values (4.15 vs 4.88 kg) and lower collagen solubility (34.61 vs 22.58%). LM and M. semitendinosus (ST) of the supplemented deer had a higher content of fat (pasture vs concentrate feeding: 0.56 vs 0.72% in LM; 0.55 vs 0.78% in ST) and provided lower PUFA, particularly n-3 PUFA, and higher n-6/n-3 ratio (3.30 vs 4.76 in LM; 3.39 vs 4.63 in ST). Thirty-month-olds' LM and ST were fatter than 18-month-olds', and provided lower PUFA, both in the n-6 and n-3 fraction.     

Polarization reversal,migration related shifts in human resource profiles,and spatial growth policies: a Venezuelan study

"This article examines polarization reversal in terms of changing human resource profiles related to migration and to national policies affecting the spatial pattern of economic growth. It first demonstrates the relationship between these elements through a review that integrates three distinct themes in earlier research. Attention then turns to an empirical study of human resource variation among eight urban districts and the rest of Venezuela treated as a single unit. This comparison utilizes age, gender, educational attainment, and occupational status variables provided by individual records of Venezuela's 1971 Population Census. A concluding section relates empirical findings to policy alternatives."     

Location,social categories,and individual labor market experiences in developing economies: the Venezuelan case

"Individual labor market experiences [in Venezuela] are examined in terms of educational attainment, labor force participation, and wages received. Explanatory factors include personal attributes and two multivariate scales measuring place characteristics related to development. The results indicate that place characteristics associated with development have important effects on labor market experiences.... Among the key findings of this research are that educational attainment most affected labor force participation by women and wages of men."     

Sound field calculation for rectangular sources

A method is presented for calculation of the sound field from a rectangular continuous-wave source surrounded by a plane grid baffle. The approach is illustrated for square sources of 0.5, 1, 2, 5, 10, 20, and 100 lambda on a side. These results are compared to the sound fields produced by similarly sized circular sources. The beam widths and locations of on-axis minima are similar for the two sources, but the transverse pressure distribution is more uniform in the near-field of the square source. The effects of attenuation on the sound field of a square source are examined.     

Diode-laser-pumped Nd:YAG laser injection seeding system

We have designed and tested a compact injection seeding system consisting of a diode-laser-pumped Nd:YAG master oscillator and a permanent-magnet Faraday isolator. With active resonator frequency stabilization, this system permits highly reliable single-axial-mode operation of a Q-switched Nd:YAG laser over a period of hours. The system is capable of injection seeding both stable and unstable resonator designs and is suitable for injection seeding commercial lasers with only minor modifications.