Vendor Selection with Bundling: A Comment*

In a recent article by Rosenthal, Zydiak, and Chaudhry (1995), a mixed integer linear programming model was introduced to solve the vendor selection problem for the case in which the vendor can sell items individually or as part of a bundle. Each vendor offered only one type of bundle, and the buyer could purchase at most one bundle per vendor. The model employed n(m+ 1) binary variables, where n is the number of vendors and m is the number of products they sell. The existing model can lead to a purchasing paradox: it may force the buyer to pay more to receive less. We suggest a reformulation of the same problem that (i) eliminates this paradox and reveals a more cost-effective purchasing strategy; (ii) uses only n integer variables and significantly reduces the computational workload; and (iii) permits the buyer to purchase more than one bundle per vendor.     

论《狮子王》、《王的男人》、《夜宴》对《哈姆莱特》的改写——以对哈姆莱特“俄狄浦斯情结”的改写为中心

当代三部影视作品《狮子王》、《王的男人》和《夜宴》是基于弗洛伊德学说对《哈姆莱特》进行的改写，它们由弗洛伊德对哈姆莱特“俄狄浦斯情结”的精神分析式阐释生发而成，旁证了弗洛伊德观点的影响力，并为我们重新考量弗洛伊德的哈姆莱特阐释提供了新的启示和机会。     

Development of a Unit Risk Factor for 1,3-Butadiene Based on an Updated Carcinogenic Toxicity Assessment

The Texas Commission on Environmental Quality (TCEQ) has developed an inhalation unit risk factor (URF) for 1,3-butadiene based on leukemia mortality in an updated epidemiological study on styrene-butadiene rubber production workers conducted by researchers at the University of Alabama at Birmingham. Exposure estimates were updated and an exposure estimate validation study as well as dose-response modeling were conducted by these researchers. This information was not available to the U.S. Environmental Protection Agency when it prepared its health assessment of 1,3-butadiene in 2002. An extensive analysis conducted by TCEQ discusses dose-response modeling, estimating risk for the general population from occupational workers, estimating risk for potentially sensitive subpopulations, effect of occupational exposure estimation error, and use of mortality rates to predict incidence. The URF is 5.0 × 10⁻⁷ per μg/m³ or 1.1 × 10⁻⁶ per ppb and is based on a Cox regression dose-response model using restricted continuous data with age as a covariate, and a linear low-dose extrapolation default approach using the 95% lower confidence limit as the point of departure. Age-dependent adjustment factors were applied to account for possible increased susceptibility for early life exposure. The air concentration at 1 in 100,000 excess leukemia mortality, the no-significant-risk level, is 20 μg/m³ (9.1 ppb), which is slightly lower than the TCEQ chronic reference value of 33 μg/m³ (15 ppb) protective of ovarian atrophy. These values will be used to evaluate ambient air monitoring data so the general public is protected against adverse health effects from chronic exposure to 1,3-butadiene.     

Experiment-dependent priors in psychology and physics

Sometimes conducting an experiment to ascertain the state of a system changes the state of the system being measured. Kahneman & Tversky modelled this effect with support theory. Quantum physics models this effect with probability amplitude mechanics. As this paper shows, probability amplitude mechanics is similar to support theory. Additionally, Viscusi's proposed generalized expected utility model has an analogy in quantum mechanics.     

The Interaction Between Role Structures and Self-Conceptions in Fostering Different Types of Self-Esteem in Innovative and Traditional Elementary Schools*

A two-dimensional model of inner and outer self-esteem is discussed wherein inner self-esteem is hypothesized to be an outcome of self-evaluations of performance in prominent role identities. Outer self-esteem is hypothesized to be related to self-evaluations of both prominent and nonprominent role identities. The research context is a comparison of the different processes facilitating self-esteem in innovative schools (emphasis on student-initiated activities and control) and traditional (emphasis on pre-determined curriculum and teacher-administrator control). Data across school type demonstrate a modest correlation between positive self-evaluations of performance in prominent role identities and both types of self-esteem. The data suggest that high evaluation of performance in nonprominent role identities is related to outer self-esteem but not to inner self-esteem. Further empirical clarification of the concepts was established by viewing the relationships within school type. In the innovative schools both types of self-esteem were predominantly related to positive evaluations of prominent role identities, whereas in the traditional schools both types of self-esteem were related to both performance in prominent and nonprominent role identities. Thus the theoretical distinction gained partial support while the process of gaining self-esteem was shown to be essentially different between alternate school structures. Controls for social desirability, race, sex, and father's occupation did not change these findings.     

Processes of adjustment in organized out-of-school activities: opportunities and risks

Participation in organized out-of-school activities leads to long-term psychosocial and educational benefits for young people. Now we're learning which features of these activities best support individual children.