Since compact bone is demonstrably anisotropic and inhomogeneous, the measured quantities yield a plesio-velocity rather than a true sonic velocity, which makes it difficult to compare velocity measurements among several bone samples. Distribution of the plesio-velocity for 11 pairs of 2 mm thick specimens from a single mature bovine compact bone sample using 100-ns well-damped sonic pulses emitted by a 10-mHz transducer show that anisotropy exists in both axial and transverse directions and must be associated with the local structure and composition. Changes in the same specimens when wet, dry, and rehydrated show an increase in velocity and anisotropy of the dry over the wet state. The plesio-velocity is greater in the axial direction, along the bone axis, than in the transverse plane. The change in plesio-velocity from wet to dry bone is greatest along the bone axis and least in the transverse plane. Changes in dimension, when the bone specimens were dried, show the bone sample to be anisotropic in this parameter also, but in the reverse order from that for the plesio-velocity. Shrinkage is least along the osteons and a maximum in the transverse plane.
Dimensional stability of a demineralized bovine cortical bone sample was found in all media whether EDTA, saline or ethanol and water solutions or even 100% ethanol. A 6% volume shrinkage was observed, in strong contrast to the reported swelling for tail tendon fiber collagen. Sonic velocity was strongly dependent on the state and the medium, varying by a factor greater than 2. The medium appears to contribute strongly to the observed velocity suggesting that the Reuss formalism is applicable with the solid collagen skeleton as one component and the liquid in the pores as the second. Sonic anisotropy was noted although the intensity varied. The radial to axial velocity was greatest (0.93) in saline and least in 100% ethanol (0.80) indicating that the rigidity of the tissue influenced the character of sonic propagation. Two sets of intermolecular linkages are inferred. One set, in common with tendon collagen, controls the elastic properties. A second set in bone collagen maintains dimensional stability.
In the context of increasingly dynamic global threats to security, which exceed current institutional capabilities to address them, this paper examines the influence of actors with insular interests who seek to leverage anxieties, grievances and disinformation for their own advantage at the expense of the public. Such actors have a common interest in political dysfunction as a means of reducing institutional controls and oversite and use combinations of divisive messaging and disinformation to advance societally suboptimal goals. We first examine the emergence of a security deficit arising from globalization, climate change, and society’s failure to develop the institutions and norms necessary to address the threats produced by these combined phenomena. We then analyze how the politics of division and disinformation have undermined the ability of political and social systems to adapt to the new global threat landscape, employing a conceptual framework that integrates perspectives from sociology and political studies with advances in the cognitive sciences and psychology. Included in the analysis is an examination of the psychological and cognitive foundations of divisive politics and disinformation strategies employed by opportunistic actors to manipulate existing cultural biases and disinform the public of the genuine threats to their well-being. Finally, we provide examples of the interaction of the aforementioned dynamics and concomitant societal opportunity costs resulting from politically fueled division and disinformation. The paper intends to integrate insights from distinct disciplines (sociology, political science, political economy, psychology and cognitive science) to construct a new conceptual framework for understanding obstacles to addressing twenty-first century global threats, and identify gaps in the capacity of dominant security paradigms to fully recognize and assess such threats.
A considerable amount of interest in the past several years has been devoted to the characteristics and dynamics of the fast-growing information technology (IT) industry in the United States (U.S.). Particular attention has been focused on how gains from increasing computer and Internet use are distributed across society. Do all segments of society enjoy the same level of access and use of computers and the Internet, or do some segments of society benefit more from computer and Internet use than others? This question has engaged a widespread and prolonged debate surrounding the issues of fairness of IT participation and use in the U.S. By the same token, many in recent years have also focused on how interest in IT and computer and Internet use are distributed across society. In this article, I focus attention on gender participation in IT: Are there differences in both interest in IT as a profession, and computer and Internet use across the U.S., and do these differences persist among young people? While there is considerable evidence that gaps in Internet access and use by gender have largely disappeared (Mossberger, Tolbert, & Stansbury, 2003; Companie, 2001; Norris, 2001; Warschauer, 2003), there is a growing concern that differences in interest in the IT industry by gender are, in fact, widening. Although evidence suggests that the societal gender gap in Internet access and use has largely disappeared, a gender gap in IT professions still exists and, in fact, is widening. Measuring the magnitude of the gap is complicated because there are varying definitions as to which occupations comprise the core IT professions. Using data from the U.S. Department of Commerce, Current Population Survey (CPS), Meares and Sargent identify four core IT occupations: computer scientists, computer engineers, systems analysts, and computer programmers (1999, pp. 3-4), while The Council of Economic Advisors identifies five core IT occupations: electrical and electronic engineers, computer systems analysts and scientists, operations and systems researchers and analysts, computer programmers, and computer operators (The Council of Economic Advisors, 2000, p. 3). Assuming that working in an IT occupation constitutes interest in the field, then if the level of participation among women in IT declines, presumably, so does their interest in the IT industry.
The rapid pace of international growth in Internet use is putting enormous pressure on nations to acquire Internet technology in order to compete in the global economy. In the USA, even as Internet access is being disseminated widely throughout society, Internet technology is rapidly changing to meet the growing demands for information. Cheaper and slower dial-up access is being replaced by high-speed broadband access (Horrigan, 2006, p. ii; NTIA, 2004, p. 1). Broadband access provides many advantages over slower dial-up service. In addition to faster and easier Web navigation, more information is becoming available and in greater variety. As a result, the typical Web search time has been greatly reduced and access to information and applications such as higher quality graphics are becoming more widespread. Broadband access is growing at a faster rate than dial-up access (Horrigan, 2006, p. iv). Evidence suggests that broadband users are more likely to use the Internet in a wider variety of ways than traditional dial-up users. Since broadband is always connected, making access easier than ever, it has the potential to greatly affect the frequency and duration of user sessions, type of search, and location of access. As often stated, “While modem use is disruptive, broadband use is integrative” (The Digital Future Project, 2005, p. 4). According to one survey, 69% of broadband users go online on a typical day, compared to 51% using dial-up service. As applications of broadband activity widen, the typical delays encountered in accessing dial-up service are avoided. As the global competitive environment intensifies, there is an economic imperative to prepare American K-12 students for this new reality (Honey et al., 2005). As broadband expansion throughout society increases, its potential impact on education is deepening. Its role has expanded beyond just enhancing the traditional classroom curriculum toward an integrated part of the educational curriculum. As schools increasingly assign work requiring online searches, students are encouraged to use broadband to complete assignments. Those without access will be at an increasing disadvantage. In response, public schools have made substantial gains in acquiring Internet technology in recent years and nearly all currently have broadband Internet access as well. In 2003, 95% of all public schools with Internet access used broadband (Parsad & Jones, 2003, p. 3). This represents a 15% increase in broadband use since 2000. Furthermore, public schools are increasingly improving access for disadvantaged students by providing additional availability around normal school hours for those that do not have at home access. The intent of this article is to examine current broadband use and its potential impact on overall educational experiences of school-age children. Does increased broadband use among children have a positive effect on the frequency, duration, manner, and type of Internet use as well as educational performance? Are children now using it more frequently for education and for research and information gathering purposes?
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