An examination of the mechanical interaction of drilling slurries at the soil-concrete contact

Evidence gained from previous field tests conducted on drilled shaft foundation shows that using drilling slurries to stabilize a borehole during the construction may influence the interfacial shear strength. This paper deals with an exhaustive study of the effects of drilling slurries at the contact between soil and concrete. This study involved adapting a simple shear apparatus and performing approximately 100 experimental tests on the interaction between two types of soils; clay and sandy clay and five specimens of concrete with different surface shapes. It also involved using bentonite and polymer slurries as an interface layer between soil and concrete. Results showed that an interface layer of bentonite slurry between clay and concrete decreases the interfacial shear strength by 23% and as an interface layer between sandy clay and concrete, bentonite increases interfacial shear strength by 10%. Using polymer slurry as an interface layer between clay and concrete decreases the interfacial shear strength by 17% while using it as an interface layer between sandy clay and concrete increases the interfacial shear strength by 10%. Fur- thermore, the data show that using bentonite and polymer slurry as an interface layer between clay and concrete decreases the sliding ratio by 50% to 60%, while increasing the sliding ratio by 44% to 56% when these are used as an interface layer between sandy clay and concrete.     

Catalytic dechlorination and detoxification of 1-（2-chlorophenyl） ethanol by Pd/Fe

1-（2-chlorophenyl） ethanol （CPE） is of health and environmental concern due to its toxicity and its use as an intermediate in pharmaceutical manufacturing. The current work deals with the catalytic reductive dechlorination and detoxification of CPE by Pd/Fe bimetal. CPE was effectively dechlorinated to l-phenyl ethanol （PE） accompanied by the equivalent release of chloride. The extent of CPE dechlorination increased with temperature, Fe dosage and Pd loading. A decrease in solution pH increased CPE dechlorination, resulting presumably from an increase in hydrogen production. Under the specific conditions of 20 g/L Pd/Fe, 0.10% Pd （w/w） and initial pH 5-6, the CPE dechlorination was completed within 145 rain. The dechlorination followed a pseudo-first-order kinetics with an activation energy of 56.7 kJ/mol. The results of toxicity testing showed that CPE was very toxic to Chlorella, whereas PE showed little toxicity. The toxicity of the reaction solution declined gradually and the promoting effects on Chlorella intensified consequently with the dechlorination process. Thus, the reductive dechlorination of CPE to PE by Pd/Fe was a detoxification process. It may be used to effectively reduce the toxicological effects of CPE-contaminated wastewater, thereby enhancing the performance of subsequent biological processes in wastewater treatment.     

Revisiting the association between reading achievement and antisocial behavior: new evidence of an environmental explanation from a twin study

Previous studies have reported, but not explained, the reason for a robust association between reading achievement and antisocial behavior. This association was investigated using the Environmental Risk (E-Risk) Longitudinal Twin Study, a nationally representative 1994-1995 birth cohort of 5- and 7-year-olds. Results showed that the association resulted primarily from environmental factors common to both reading and antisocial behavior and was stronger in boys. Environmental factors also explained the relation between reading disability and conduct disorder. Leading candidate environmental risk factors weakly mediated the association. For boys the best explanation was a reciprocal causation model: poor reading led to antisocial behavior, and vice versa. In contrast, the relation between reading achievement and attention deficit hyperactivity disorder was best explained by common genetic influences.     

Contemporaneous and longitudinal associations between social behavior and literacy achievement in a sample of low-income elementary school children

This study investigates associations between social skills (aggression and prosocial behavior) and literacy achievement in a sample of low-income children (between 4 and 6 years old when the study began) during elementary school. Results revealed consistent associations between social skills and literacy achievement in the first, third, and fifth grades, but the patterns of the associations were different for aggression and prosocial behavior. While the strength of the association between aggression and literacy achievement increased over the elementary grades, the association between prosocial behavior and literacy achievement decreased. In addition, path analyses revealed that poor literacy achievement in the first and third grades predicted relatively high aggressive behavior in the third and fifth grades, respectively.     

Demographic characteristics and rates of progress of deaf and hard of hearing persons receiving substance abuse treatment

A lack of demographic information and data related to the achievement of short-term goals during substance abuse treatment among persons who are deaf or hard of hearing dictated the need for the study. New York State maintains a database on all individuals who participate in treatment. Within this database, 1.8% of persons in treatment for substance use disorder (SUD) were also deaf or hard of hearing. As hypothesized, members of the deaf and hard of hearing sample were older, likelier to be white, and likelier to be female, relative to the SUD-only group. For both groups, alcohol, heroin, and cocaine had the highest rates of reported use. Achievement of short-term goals in the areas of alcohol use, drug use, vocational/educational goals, and overall goals indicated no differences between the deaf and hard of hearing group and the SUD-only group. Implications of these findings are discussed.     

Recognizing the face of Johnny, Suzy, and me: insensitivity to the spacing among features at 4 years of age

Four-year-olds were tested for their ability to use differences in the spacing among features to recognize familiar faces. They were given a storybook depicting multiple views of 2 children. They returned to the laboratory 2 weeks later and used a "magic wand" to play a computer game that tested their ability to recognize the familiarized faces and their own face based on the spacing of features. Children performed at chance levels. Follow-up studies confirmed that they had attended to internal facial features and validated the stimuli. The results contrast with studies showing some sensitivity to the spacing of features in infants and preschool children; multiple mechanisms of face processing may make use of spatial relations and develop at different rates.     

探究教学的认知理论

本文选用多学科教学实例来说明教师如何运用探究教学的十种策略促使学生解决各种问题。在这一过程中,学生既学习知识领域的具体理论,又学习各种推理技能,包括构建假设、验证假设、提出预测、选择验证理论的合适的案例、提出反例和假设案例、区别必要条件和充分条件、考虑不同的假设、熟悉规则或理论可能的形式、知道提问的策略等。在某种意义上,探究法为学生展示了一个造就科学家的模拟过程。这种教学模式对学生的学习有特别的激励作用。     

Human cancer genetics

Cancer is a genetic disorder.Although heredi-tary cancers account for only a small fraction of all tumors,most cancers are caused by a variable mix of heredity and environment that leads to accumulations of genetic alterations and then uncontrolled cell pro-liferations(Kops et al.,2005).In addition,genetic alteration is one of the a few most important bio-logical factors that determine the diagnosis and prognosis of different cancers and dictate the treat-ment strategies for cancer patients.Fu…     

Doulas as community health workers: lessons learned from a volunteer program

Doulas, women who primarily provide social support during childbirth, have been associated with a number of positive health outcomes. Because the primary model of practice for doulas is a fee-for-service model in which families privately hire a doula, many expectant women who could benefit from doula support are unable to access the service. The Doulas Care program, located in Ann Arbor, Michigan, represents one model in which doulas provide services without charge. As a result of their extended role in the community, doulas who work with the Doulas Care program have unique educational needs. Through the use of focus groups with the program's volunteer doulas, educational needs related to overcoming barriers to being a doula working in the community were identified. Recommendations for education and training are made to improve the support doulas offer as community health outreach workers.