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For shooting scene reconstruction purposes, knowledge about the ricochet behavior of bullets provides valuable information. In this study, the critical ricochet angles of four cartridge types were established on plain float glass. The estimates of the critical ricochet angles varied between cartridge types and were 21.0° for .32 Auto FMJ bullets, 15.8° for 9 mm Luger FMJ bullets, 17.6° for .45 Auto FMJ bullets, and 21.3° for 9 mm Luger, Action NP bullets. The corresponding ricochet and deflection angles per incidence angle varied depending on the state of the ricocheted bullets. The mean ricochet angles are always lower than the corresponding angles of incidence, and the mean ricochet angles for the FMJ bullets with undamaged jackets are lower than those of bullets where the jacket is either damaged or the bullet partially ricocheted and partially perforated. Mean ricochet angles are lower for undamaged FMJ bullets than for undamaged Action NP bullets.  相似文献   
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Resilience research requires attention to the factors that promote youth development and success. Youth success is associated with youth having adults in their lives who care about them and set high expectations for them to succeed; oftentimes these adults are presumed to be the children's parents. Because youth spend a great deal of time in schools, school settings may be a place where youth resilience can be fostered. In 2004, 6th-grade youth in 5 schools in Maricopa County, Arizona, were surveyed to determine if they had factors to promote their resilience. In these schools, teachers had been trained by an agency called Kids at Hope. Kids at Hope presupposes that “all children are capable of success, no exceptions” and offers an alternative paradigm to kids at risk. The results of this research show that youth who believe that they are successful and who are optimistic about themselves and their schools are more likely to find their schools to be places where they can be successful and optimistic.  相似文献   
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Forensic firearm examination provides the court of law with information about the source of fired cartridge cases. We assessed the validity of source decisions of a computer‐based method and of 73 firearm examiners who compared breechface and firing pin impressions of 48 comparison sets. We also compared the computer‐based method's comparison scores with the examiners' degree‐of‐support judgments and assessed the validity of the latter. The true‐positive rate (sensitivity) and true‐negative rate (specificity) of the computer‐based method (for the comparison of both the breechface and firing pin impressions) were 94.4% and at least 91.7%, respectively. For the examiners, the true‐positive rate was at least 95.3% and the true‐negative rate was at least 86.2%. The validity of the source decisions improved when the evaluations of breechface and firing pin impressions were combined and for the examiners also when the perceived difficulty of the comparison decreased. The examiners were reluctant to provide source decisions for "difficult" comparisons even though their source decisions were mostly correct. The correlation between the computer‐based method's comparison scores and the examiners' degree‐of‐support judgments was low for the same‐source comparisons to negligible for the different‐source comparisons. Combining the outcomes of computer‐based methods with the judgments of examiners could increase the validity of firearm examinations. The examiners' numerical degree‐of‐support judgments for their source decisions were not well‐calibrated and showed clear signs of overconfidence. We suggest studying the merits of performance feedback to calibrate these judgments.  相似文献   
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Stem cells have enormous potential in medicine. Stem cell research is allowedsometimes just for to a limited extent in a large minority of countries. Nevertheless, the research and use of stem cells should be encouraged.  相似文献   
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Federal first responder funding is estimated to be $98 billion below the minimum required level over the 5 years ending in 2010. A significant portion of that shortfall can be covered by savings attained by eliminating non-public-good services, initiating public–private partnerships for meeting peak time demand in emergency situations, and contracting-out other public services. We concentrate on such savings in the context of response to false calls to police, fire, and ambulance services. Solving the false alarm problem for police, fire, and ambulance services and eliminating some non-public-good police services could release significant service-hours and 23.7–31.4% of the required additional Homeland Security (HLS) annual spending. Reducing false alarms means 88,000 police, fire, and ambulance first responders could be shifted to HLS activities.
Andrew J. BuckEmail:
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At the forefront of modern debate over the ethical use of biotechnology is embryonic stem cell research. In this poignant analysis of its legitimacy, the author examines the history of this research in light of the United States' policy favoring the protection of human beings over scientific progress. Stem cells, which can divide in culture to create specialized cells in the human body, possess significant potential for curing disease, particularly when taken from human embryos. However, as evidenced by the research atrocities committed under the Nazi regime, the benefits of human research do not come without a cost to humanity. Recognizing this, the later trial of these scientists produced the Nuremberg Code, a set of natural law principles guiding future research on humans that continues to influence health policy decisions. Drawing on this background, the author first considers the appropriate legal status for a human embryo. Biologically, the characteristics of a human embryo place it between human tissue and a constitutional person. Judicially, the answer is even less clear. The author analyzes case law in the context of abortion and in vitro fertilization, as well as classifications by the common law, state legislation, and the National Bioethics Advisory Commission, to conclude that a human embryo should be subject to the same legal and ethical restrictions as any other "human subject." Accordingly, the author argues that embryonic stem cell research violates the ethical standards and purposes of the Nuremberg Code and should be banned by federal legislation. Such a prohibition will fulfill the societal policy choice of protecting potential life and vulnerable human subjects.  相似文献   
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