Modeling the Time to Fail of Peach Nectars Formulated by Hurdle Technology

The use of regression with life-data is helpful to observe whether one or more factors affect the failure time (spoilage) of a product, obtaining a model that predicts the time to fail (TTF). TTF models link kinetic (lag time) and probabilistic (growth /no-growth prediction) models for selected formulation/storage conditions. Our objective was to assess the individual and combined effects of pH, a_w, and the incorporation of potassium sorbate (KS) or sodium benzoate (BNa) at selected concentrations on the microbial stability of peach nectar during storage at 25°C, in order to model and predict TTF. Peach nectars were formulated with 40% fruit pulp and the necessary sucrose syrup and citric acid to attain a_w 0.96, 0.97, or 0.98 and pH 3.0, 3.5, or 4.0; while 0, 500, or 1000ppm of KS or BNa were added. Nectars were stored for 180 days in glass jars at 25°C, and periodically analyzed (standard plate as well as yeast and mould counts). The experimental design and analyses were replicated three times. Storage times that revealed microbial populations higher than 10⁴ CFU/mL and signs of spoilage were registered to model TTF by survival analysis. From the 54 combinations tested, 9 formulations (without antimicrobials) exhibited early spoilage (<5 days). For the combinations formulated with 500ppm of BNa, spoilage was detected after 30 days; much longer spoilage times were observed for nectars with 1000ppm of KS or BNa. In general, KS was more effective than BNa in delaying spoilage when 1000ppm were added. TTF models included individual and interaction effects of the evaluated factors and revealed good agreement among experimental and predicted data (R²>0.90). Survival analysis through TTF models can be used to predict spoilage time under specific factor combinations or to select factor levels for a specific shelf-life of peach nectars.     

Mind-set and close relationships: When bias leads to (in)accurate predictions.

The authors investigated whether mind-set influences the accuracy of relationship predictions. Because people are more biased in their information processing when thinking about implementing an important goal, relationship predictions made in an implemental mind-set were expected to be less accurate than those made in a more impartial deliberative mind-set. In Study 1, open-ended thoughts of students about to leave for university were coded for mind-set. In Study 2, mind-set about a major life goal was assessed using a self-report measure. In Study 3, mind-set was experimentally manipulated. Overall, mind-set interacted with forecasts to predict relationship survival. Forecasts were more accurate in a deliberative mind-set than in an implemental mind-set. This effect was more pronounced for long-term than for short-term relationship survival. Finally, deliberatives were not pessimistic; implementals were unduly optimistic. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison between a Weibull proportional hazards model and a linear model for predicting the genetic merit of US Jersey sires for daughter longevity

Predicted transmitting abilities (PTA) of US Jersey sires for daughter longevity were calculated using a Weibull proportional hazards sire model and compared with predictions from a conventional linear animal model. Culling data from 268,008 Jersey cows with first calving from 1981 to 2000 were used. The proportional hazards model included time-dependent effects of herd-year-season contemporary group and parity by stage of lactation interaction, as well as time-independent effects of sire and age at first calving. Sire variances and parameters of the Weibull distribution were estimated, providing heritability estimates of 4.7% on the log scale and 18.0% on the original scale. The PTA of each sire was expressed as the expected risk of culling relative to daughters of an average sire. Risk ratios (RR) ranged from 0.7 to 1.3, indicating that the risk of culling for daughters of the best sires was 30% lower than for daughters of average sires and nearly 50% lower than than for daughters of the poorest sires. Sire PTA from the proportional hazards model were compared with PTA from a linear model similar to that used for routine national genetic evaluation of length of productive life (PL) using cross-validation in independent samples of herds. Models were compared using logistic regression of daughters' stayability to second, third, fourth, or fifth lactation on their sires' PTA values, with alternative approaches for weighting the contribution of each sire. Models were also compared using logistic regression of daughters' stayability to 36, 48, 60, 72, and 84 mo of life. The proportional hazards model generally yielded more accurate predictions according to these criteria, but differences in predictive ability between methods were smaller when using a Kullback-Leibler distance than with other approaches. Results of this study suggest that survival analysis methodology may provide more accurate predictions of genetic merit for longevity than conventional linear models.     

网络时代中图书馆的生存与发展

网络时代图书馆地位逐渐动摇,本文从图书馆面临的冲击,图书馆的应对,图书馆未来需要自身转型三个方面探讨了未来图书馆的生存与发展.     

Organizations as self-organizing and sustaining systems: a complex and autopoietic systems perspective

Many alternative theories about organization exist. Despite this, or perhaps because of it, adequate explanation of the relationship between macro and micro processes of organization, and organizational dynamics remains elusive. In the recent past there has been growing interest in two areas of systems science that offer a different basis for understanding the generative and dynamic qualities of organizations. These are autopoietic theory and complex adaptive systems theory. In this paper, we outline a theory of organization built on a synthesis of these two theoretical strands. It is argued that the approach provides an improved framework for understanding the nature and dynamics of organizational phenomena, and as such a more rigorous basis upon which to base future organizational research.     

Vibrio parahaemolyticus in granulated ark shell clam (Tegillarca granosas): accumulation from water and survival during cold storage and thermal process

This study investigated accumulation of Vibrio parahaemolyticus in granulated ark shell clam (Tegillarca granosas) exposed to contaminated water and survival of V. parahaemolyticus in the clams during cold storage and heating processes. Vibrio parahaemolyticus could be accumulated in clams to a level similar to that of contaminated water within 12 h of exposure of clams to contaminated water at temperatures between 9 and 33 °C. Keeping clams stored at 5 and 0 °C for 10 days resulted in 1.98 and 2.32 log MPN g^?1 reductions of V. parahaemolyticus, respectively, in the clams. Frozen storage at ?18 °C for 15 days or at ?30 °C for 30 days were capable of reducing V. parahaemolyticus from 4.05 log MPN g^?1 to non‐detectable levels (< 3 MPN g^?1). A heating process in hot water at 80 °C or higher for 1 min also reduced V. parahaemolyticus in the clams to non‐detectable levels.     

信息异化现象研究综述

目前，信息异化问题是一个新问题，也是一个被深入研究的问题。该文阐释了信息异化的内涵和本质，并从主体的情感、认知与行为三个方面的新视角出发，对诸多信息异化现象进行了归类与分析。     

Suicidal ideation and its recurrence in boys and men from early adolescence to early adulthood: An event history analysis.

Occurrence and recurrences of suicidal ideation (SI) were modeled among boys/men assessed annually from ages 12 to 29 years. Multiple-spell discrete-time event-history analyses permitted (a) determination of whether risk for SI escalates with prior experiences of SI (spell effects), while (b) accounting for changes in risk with time (period effects) and (c) controlling for vulnerability factors. Self-reported SI (presence/absence in past week), depressive symptoms, alcohol/substance use, antisocial behavior, and official arrest records were collected annually from 205 boys recruited on the basis of community risk for delinquency. Parents' self-reported psychopathology and SES were collected in childhood. Period effects supported decreasing risk for SI over time. Spell and time-varying 1-year lagged substance use and depressive symptoms independently predicted increased risk for SI. Models involving SI with intent were explored. Consistent with interpersonal psychological theory, risk for young men's SI increases with past experience of SI, even with key propensities controlled. However, risk also decays over time. Targeting conditions that confer risk for SI is essential. Preventing and delaying SI occurrence and recurrence may represent independent mechanisms by which prevention efforts operate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A method to consider replaced pipes in modeling of sewer pipe deterioration

Statistical models that predict the deterioration of sewer pipes are useful for planning financial resources required for sewer renewal. Usually, data that are available to calibrate these models solely concern pipes that are still in place, leading to underestimated deterioration rates. A new method is proposed to consider possible past replacement of pipes in the statistical modeling of their deterioration. The proposed method considers the aging of pipes, simulated with a Cox model, and their probability to be replaced separately. Application to a synthetic sewer network, for which it was assumed that information regarding all pipe replacements over the lifetime of the network was available, showed that the proposed method allows for improved predictions of the sewer deterioration model, when compared to predictions of a model calibrated without considering the information about replaced pipes.