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The quantity of mitochondrial DNA (mtDNA) template added for amplification and subsequent dye terminator reactions is critical for obtaining quality sequence data. Validation of a human mtDNA real‐time quantitative PCR (qPCR) assay demonstrated its high degree of reproducibility and precision as well as an extremely sensitive threshold of detection (0.0001 pg/μL or approximately six human mtDNA copies/μL). A study of 35 nonprobative bone and teeth evidence samples revealed that 20 pg of mtDNA template is recommended for successful HV1 and HV2 sequence analysis; however, as little as 0.013 pg can generate a full mtDNA profile when using enhanced amplification reactions. The assay can also detect PCR inhibition and is useful for identifying samples that may benefit from re‐purification. Overall, the assay is an excellent method to quantify mtDNA and is useful for determining the best analytical approach for successful sequencing.  相似文献   
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The occurrence of secondary DNA transfer has been previously established. However, the transfer of DNA through an intermediary has not been revisited with more sensitive current technologies implemented to increase the likelihood of obtaining results from low‐template/low‐quality samples. This study evaluated whether this increased sensitivity could lead to the detection of interpretable secondary DNA transfer profiles. After two minutes of hand to hand contact, participants immediately handled assigned knives. Swabbings of the knives with detectable amounts of DNA were amplified with the Identifiler® Plus Amplification Kit and injected on a 3130xl. DNA typing results indicated that secondary DNA transfer was detected in 85% of the samples. In five samples, the secondary contributor was either the only contributor or the major contributor identified despite never coming into direct contact with the knife. This study demonstrates the risk of assuming that DNA recovered from an object resulted from direct contact.  相似文献   
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Sexual risk taking among female delinquents represents a significant public health problem. Research is needed to understand the pathways leading to sexual risk taking among this population. This study sought to address this issue by identifying and testing two pathways from child maltreatment to non-condom use among 329 White and 484 African American female adolescent detainees: a relational pathway and a substance use coping pathway. The relational pathway indicated that child maltreatment would be related to non-condom use via depressive self-concept and condom use self-efficacy. The substance use coping pathway suggested that depressive self-concept and alcohol-based expectancies for sexual enhancement would mediate the relationship between child maltreatment and non-condom use. As hypothesized, the relational pathway variables were associated with one another in the expected directions; however, evidence of mediation was not found. Support for mediation was found for the substance use coping pathway. Exploratory across group comparison analysis indicated that the relational pathway was significant for White girls whereas the substance use coping pathway was significant for African American girls. Limitations and implications for future research are discussed.  相似文献   
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The purpose of this article is to examine the attitudes and substance use behaviors of African American adolescents living in the Midwest. A baseline survey was administered to 463 African American teens between the ages of 11-19. The article examines the relationship between attitudes toward drugs and drug-using behavior in this African American sample. Drug use will be compared to national drug use norms established by the Youth Risk Behavior Surveillance Survey. Overall participants had fairly negative attitudes toward drugs. Sixty percent of the sample reported that they were committed to a drug-free life, 74% had made a decision to stay away from marijuana, 79% reported making a decision not to smoke cigarettes, and 71% reported they would not get drunk in the next year. Females were more likely to stay away from marijuana than males. In this current study there is cause for alarm; participants reported higher percentages of ever smoking cigarettes and marijuana than the Youth Risk Behavior Surveillance Survey. This study shows there is a need to provide substance abuse prevention programs for African American adolescents. Limitations and future directions are also discussed.  相似文献   
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The purpose of this article is to examine the self-reported sexual attitudes and behaviors of adolescents living in the Midwest. A survey was administered to 463 African American youths ages 11–19. The results indicate that intent to have sexual intercourse, reported likelihood toward having sexual intercourse, and whether participants felt that they would have sex in the next 3 months were predictors of whether they had sexual intercourse at the 3-month follow-up. The results also revealed that the opinions of referent others did not predict sexual intercourse at 3 months. Negative attitudes toward condoms did predict condom use at 3 months and the opinions of referent others also predicted condom use at 3 months. Limitations as well as future research are also discussed.  相似文献   
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Over the past few decades researchers have begun to examine the importance of understanding positive youth development and the many contexts in which youth find themselves. The social contexts in which adolescent development occurs are varied and complex, particularly the development among African American youth. African American youth are faced with a number of challenges including living in single-parent homes, high teen pregnancy rates, and poor neighborhoods, yet many of these youth continue to thrive. The purpose of this study was to examine the relationship between family structure (single-parenting) and adolescent outcomes such as educational aspirations and sexual activity among African American adolescent youth aged 12–17. Approximately 462 African American youth were surveyed. A number of positive results emerged; for instance, there was a negative correlation between family structure and educational aspirations. The number of parents in the home did not interfere with youth wanting to complete high school and go on to college (r = ? .218, r² = .04, p < .05). The results also showed that as educational aspirations increased, the number of sexual partners decreased (r = ? .141, meaning that the more adolescents reported a desire to complete high school, they were less likely to report having sexual intercourse. These positive results should be promoted among African American youth so that those faced with these challenges will note that others have overcome and accomplished their goals. In this population educational aspirations were important. Limitations and future research are discussed.  相似文献   
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The purpose of this article was to assess the overall health behaviors of African American emerging adults who live in a Midwestern city. Two hundred participants, ages 18–25, completed a 129-item survey. Results indicate that African American emerging adults are engaged in relatively healthy behaviors (i.e., physical activity, low substance use). The results also showed that within the emerging adult developmental period, there are differences in behavior for those who are in the younger (18–20) versus those that are older (21–25) in the developmental period. Limitations, future research, and implications for practice will also be discussed.  相似文献   
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