Presented in this study is an analysis of the electronic properties of doped diamond calculated using the Vienna ab initio simulation package, employing density functional theory within the generalized-gradient approximation. The dopants studied here have been inserted substitutionally into a 64-atom diamond supercell and include the single-electron acceptors boron and aluminium, the single-electron donors nitrogen and phosphorus and the double-electron donors oxygen and sulphur. Co-doping of diamond with sulphur and boron has also been briefly examined. The doped supercells have been (...) relaxed, followed by calculation of electronic properties from the electronic density of states such as the indirect bandgap E g , the valence bandwidth and an examination of the acceptor and donor states in the bandgap. It is anticipated that this study will provide a useful comparison of the third- and fourth-row donors and acceptors in diamond. (shrink)

In this study an analysis is presented of the bonding and structural properties of dehydrogenated and hydrogenated doped cylindrical diamond nanowires calculated using the Vienna Ab Initio Simulation Package, employing density functional theory within the generalized-gradient approximation. The dopants studied here have been inserted substitutionally along the axis of an infinite one-dimensional diamond nanowire and include the single-electron acceptor boron and the single-electron donor nitrogen. The doped nanowires have then been re-relaxed, and properties compared with the undoped structures. The structural (...) properties of relaxed nanowires considered here include an examination bonding via the electron charge density, with the aim of providing a better understanding of the effects of dopants on the stability of diamond nanostructures and nanodevices. (shrink)

In this study an analysis is presented of the bonding and structural properties of dehydrogenated and hydrogenated doped cylindrical diamond nanowires calculated using the Vienna Ab Initio Simulation Package, employing density functional theory within the generalized-gradient approximation. The dopants studied here have been inserted substitutionally, equidistant along the axis of an infinite diamond nanowire. These dopants include aluminium, phosphorus, oxygen and sulphur. The doped nanowires have then been re-relaxed, and properties compared with previously calculated results for undoped, boron-doped and nitrogen-doped (...) structures. Structural properties of relaxed nanowires considered here include an examination bonding via the electron charge density, with the aim of providing a better understanding of the effects of dopants on the stability of diamond nanostructures and nanodevices. (shrink)

Obesity is the definitive epidemic of the modern era in the United States. Its well-documented public health impacts, especially related to children and adolescents, are horrific. Nearly one-third of American minors are overweight; over 50% of them are obese. Already, these kids suffer from multiple adverse physical and mental health conditions. Sadly, absent serious communal and individual interventions, their lives may be cut short compared to their own parents’ life expectancy. While recent surveillance suggests childhood obesity may be trending down (...) slightly in some populations, public health experts remain concerned about the threat obesity poses to the health of America's youth.The concurrent travesty underlying childhood obesity is the relative societal failure to slow and reverse its spread. (shrink)

Obesity is the definitive epidemic of the modern era in the United States. Its well-documented public health impacts, especially related to children and adolescents, are horrific. Nearly one-third of American minors are overweight; over 50% of them are obese. Already, these kids suffer from multiple adverse physical and mental health conditions. Sadly, absent serious communal and individual interventions, their lives may be cut short compared to their own parents’ life expectancy. While recent surveillance suggests childhood obesity may be trending down (...) slightly in some populations, public health experts remain concerned about the threat obesity poses to the health of America's youth.The concurrent travesty underlying childhood obesity is the relative societal failure to slow and reverse its spread. (shrink)

The widespread use of online search engines to answer the general public’s needs for information has raised concerns about possible biases and the emerging of a ‘filter bubble’ in which users are isolated from attitude-discordant messages. Research is split between approaches that largely focus on the intrinsic limitations of search engines and approaches that investigate user search behavior. This work evaluates the findings and limitations of both approaches and advances a theoretical framework for empirical investigations of cognitive biases in online (...) search activities about health-related topics. We aim to investigate the interaction between the user and the search engine as a whole. Online search activity about health-related topics is considered as a hypothesis-testing process. Two questions emerge: whether the retrieved information provided by the search engines are fit to fulfill their role as evidence, and whether the use of this information by users is cognitively and epistemologically valid and unbiased. (shrink)