Survival of salmonellae in bio-yoghurt

Many yoghurt-like products are sold with pH values of 4.5–4.6, and a potential pathogen, Salmonella infantis , was shown to survive for 10 days in typical commercial samples of 'bio-yoghurt'. Another servovar, Salmonella hadar , could not be detected after 48 h in similar products. The need to avoid contamination during the manufacture of fermented milks with pH values above those traditionally associated with yoghurt (~4.0) is stressed.     

Survival of the House Dust Mite,Dermatophagoides farinae,at High Temperatures (40–80°C)

Abstract Experiments were conducted to evaluate the survival time of randomly selected female D. farinae exposed to temperatures from 40 to 80°C and relative humidities (RHs) between 10 and 90%. Significant temperature effects were found on the length of time mites can survive under those conditions. The time needed to induce 100% mortality for female D. farinae held at 40°C varied between 39 and 84 h. At 70 and 80°C, all mites died within 5 minutes. At 50°C and above, RH had little influence and temperature alone was the determining factor for mite survival. The length of survival time decreased precipitously between 40 and 50°C, suggesting that a loss of physiological integrity of female D. farinae probably occurred in this range. The results of this study indicated that the technique of raising temperatures to above 40°C for a short duration can be used to reduce living house dust mite populations in homes significantly.     

从在研课题看园林科研

根据17家园林科研院所2003年在研课题的情况,初步总结了目前园林科研的主要特点.认为提高园林科研课题的水平,增强科研院所的生存力是当务之急,并提出了提高园林科研水平的建议.     

In situ aquatic bioassessment of pesticides applied on rice fields using a microalga and daphnids

This study assessed the effects of episodic contamination on a drainage canal adjacent to an area of intensive rice production (Coimbra, Portugal). Four monitoring periods were considered [i) before herbicide application (day -14), ii) at the first application day (day 0), iii) 3 or 5 and iv) 6 days after]. Each one consisted in three complementary evaluation lines: a) physico-chemical analyses, b) whole effluent toxicity (WET) assays with Pseudokirchneriella subcapitata, c) in situ bioassays to assess microalgae (P. subcapitata) growth, and the feeding rate and survival of Daphnia longispina and Daphnia magna. Study sites were located upstream, in a protected wetland (L1), and downstream, in the vicinity of rice fields (L2). Along with the application of agrochemicals, there was a general decrease of the water quality, especially in L2, due to nutrient and herbicide inputs. Herbicide peaks (on days 0, 5 and 6) in L2 water samples were recorded concomitantly or immediately after their application. Regarding the in situ bioassessment, the algae growth decrease from day 0 onwards in L1, whilst in L2 its inhibition was generally coherent with the decline of the water quality. Apparently, WET tests indicated that the limitation of nutrients could be affecting algae growth in L1, however, conclusions should be cautious. The feeding depression of daphnids occurred on days 0 and 5 for D. longispina and only on day 0 for D. magna, while significant reductions on survival were restricted to day 0 for both species. The impairments occurring on day 0 were linked to a potential increased toxicity driven by the ingestion of particle-bound herbicides and suspended particles. The feeding rate of daphnids provided an earlier indication of toxic impairments, though it is prompted the use of complementary endpoints and trophic levels in order to understand the cumulative effects due to various herbicide pulses.     

In vitro irradiation station for broad beam radiobiological experiments

The study of the interaction of charged particles with living matter is of prime importance to the fields of radiotherapy, radioprotection and space radiobiology. Particle accelerators and their associated equipment are proven to be helpful tools in performing basic science in all these fields. Indeed, they can accelerate virtually any ions to a given energy and flux and let them interact with living matter either in vivo or in vitro. In this context, the University of Namur has developed a broad beam in vitro irradiation station for use in radiobiological experiments. Cells are handled in GLP conditions and can be irradiated at various fluxes with ions ranging from hydrogen to carbon. The station is mounted on a 2 MV tandem accelerator, and the energy range can be set up in the linear energy transfer (LET) ranges that are useful for radiobiological experiments. This paper describes the current status of the hardware that has been developed, and presents results related to its performance in term of dose-rate, energy range and beam uniformity for protons, alpha particles and carbon ions. The results of clonogenic assays of A549 lung adenocarcinoma cells irradiated with protons and alpha particles are also presented and compared with literature.     

Practical alternatives for estimating the failure probabilities of censored life data

For censored life data, Kapur and Lamberson and O'Connor recommend the use of Johnson's formula for non-parametric estimation of the failure distribution, F(t). The formula is used to calculate the adjusted ranks of the recorded failures, which are input into the median rank estimation equation of F(t). It is our experience that Johnson's formula is fairly difficult for the reliability practitioner to understand and implement. Fortunately, an alternative formula has been developed which is much easier to use. It is demonstrated that the calculated adjusted ranks may be used in either the mean rank or median rank equations for the estimation of F(t). The question which we pose is the following: How does the performance of Johnson's estimator compare with that of the more commonly known and understood Kaplan-Meier, or product-limit, estimator?' To answer this question, the Kaplan-Meier procedure is evaluated with respect to its equivalent adjusted rank of recorded failures. The two procedures are determined to be equivalent with respect to adjusted rank criteria. Therefore, it is proved that with Johnson's estimator adapted for use with the mean rank estimator, the two procedures will yield identical estimates of the failure probabilities. Based upon this finding, it is our recommendation thatthe reliability practitioner use the alternative formula for generation of the adjusted ranks, followed by use of either the mean or median rank formula.     

Survival of human derived Lactobacillus plantarum in fermented cereal extracts during refrigerated storage

The aim of this study was to investigate the survival of a potentially probiotic Lactobacillus plantarum strain in barley, wheat and barley malt extracts. The extracts were produced from three flour/water suspensions, i.e., 5%, 20%, 30% w/w. After inoculation, the cultures were incubated for 24 h at 37 °C, and were subsequently stored at 4 °C for up to seventy days. The lactic acid and reducing sugar concentrations at the beginning of storage were significantly different between the fermented media, ranging from 0.5 g/L to 17 g/L and from 0.8 g/L to 6.5 g/L respectively, while the pH ranged between 2.9 and 3.4. It was observed that the cells survived much better in the malt extracts compared to barley and wheat extracts during refrigerated storage. Based on the results from a study using model media and supplemented cereal extracts it was derived that this was most likely due to their higher sugar concentration and the presence of protective unidentified compounds, albeit the fact that the malt extracts contained higher amounts of lactic acid.     

湿热环境对辐射损伤小鼠的影响

探讨了自然湿热环境(Hot and humid environment,HHE)及模拟HHE对辐射损伤动物的生存率、中位生存时间等的影响规律,并对其损伤机制作了初步探讨。结果表明：     

Effect of microencapsulation and resistant starch on the probiotic survival and sensory properties of synbiotic ice cream

Two types of synbiotic ice cream containing 1% of resistant starch with free and encapsulated Lactobacillus casei (Lc-01) and Bifidobacterium lactis (Bb-12) were manufactured. The survival of L. casei and B. lactis were monitored during the product’s storage for 180 days at −20 °C. The viable cell number of L. casei and B. lactis in the free state in prepared ice cream mixture was 5.1 × 10⁹ and 4.1 × 10⁹ CFU/mL at day one and after 180 days storage at −20 °C, these numbers were decreased to 4.2 × 10⁶ and 1.1 × 10⁷ CFU/mL, respectively. When we encapsulated the mentioned probiotic bacteria in calcium alginate beads, the probiotic survival raised at rate of 30% during the same period of storage at same temperature. In general, the results indicated that encapsulation can significantly increase the survival rate of probiotic bacteria in ice cream over an extended shelf-life. The addition of encapsulated probiotics had no significant effect on the sensory properties of non-fermented ice cream in which we used the resistant starch as prebiotic compound.     

Patterns of exits from housing in a homelessness system of care: the case of Calgary,Alberta

Public officials around the world seek to target subsidized housing as purposely and efficiently as possible. With limited availability of subsidized housing, it is helpful to know which household types require specific types of housing support and for how long. With this in mind, we undertake survival analysis and hazard models on clients placed into housing funded by the Calgary Homeless Foundation (CHF) to characterize patterns of exit from Calgary’s homeless system of care. To do this, we use data from Calgary’s Homelessness Management Information System from 1 April 2012 until 31 March 2015. We find singles without dependents to require housing support for the longest period of time, while families require the support for the least amount of time. One important finding is that women require housing support for longer periods of time than men (even though we control for employment and income).