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Yaghjian A.D.,Research Consultant | Stuart H.R.,LGS Innovations
IEEE Transactions on Antennas and Propagation | Year: 2010

General expressions are obtained for the lower bounds on the quality factor (Q) of electrically small electric- and magnetic-dipole antennas confined to an arbitrarily shaped volume V and excited by general sources or by global electric-current sources alone. The lower-bound expressions depend only on the direction of the dipole moment with respect to V, the electrical size of V, and the static electric and magnetic polarizabilities per unit volume of hypothetical perfectly electrically conducting and perfectly magnetically conducting volumes V. The lower bounds are obtained directly from the electromagnetic field expressions for Q with the help of current equivalence principles and the uncoupling of Maxwell's equations for electrically small volumes into quasi-electrostatic and quasi-magnetostatic fields. © 2010 IEEE. Source


Stuart H.R.,LGS Innovations | Yaghjian A.D.,Research Consultant
IEEE Transactions on Antennas and Propagation | Year: 2010

We study the effect of surrounding electrically small, top-loaded, electric-dipole antennas with a thin shell of high-permeability magnetic material. The magnetic polarization currents induced in the thin shell of magnetic material reduce the internal stored energy, resulting in a lower Qas compared to conventional designs. The simulated Q's of thin-magnetic-shell cylindrical and spherical antennas are compared to recently derived lower bounds on Q. The high permeability shells reduce the Q of these antennas to values below the lower bounds for purely global electric current sources. In the case of the spherical electric-dipole antenna, a sufficiently large value of permeability enables the $Q to be reduced to a value that is only 1.11 times the Chu lower bound. © 2006 IEEE. Source


Grudzen C.R.,Mount Sinai School of Medicine | Richardson L.D.,Mount Sinai School of Medicine | Hopper S.S.,Research Consultant | Ortiz J.M.,Mount Sinai School of Medicine | And 2 more authors.
Journal of Pain and Symptom Management | Year: 2012

Context: Palliative care focuses on the relief of pain and suffering and achieving the best possible quality of life for patients. Although traditionally delivered in the inpatient setting, emergency departments (EDs) are a new focus for palliative care consultation teams. Objectives: To explore attitudes and beliefs among emergency care providers regarding the provision of palliative care services in the ED. Methods: Three semistructured focus groups were conducted with attending emergency physicians from an academic medical center, a public hospital center, and a community hospital. The discussions were digitally recorded and transcribed to conduct a thematic analysis using grounded theory. A coding scheme was iteratively developed to subsequently identify themes and subthemes that emerged from the interviews. Results: Twenty emergency physicians participated (mean age 41 years, range 31-61 years, median practice time nine years, 40% female). Providers acknowledged many benefits of palliative care presence in the ED, including provision of a specialized skill set, time to discuss goals of care, and an opportunity to intervene for seriously ill or injured patients. Providers believed that concerns about medicolegal issues impaired their ability to forgo treatments where risks outweigh benefits. Additionally, the culture of emergency medicine - to provide stabilization of acute medical emergencies - was sometimes at odds with the culture of palliative care, which balances quality of life with the burdens of invasive treatments. Some providers also felt it was the primary physician's responsibility, and not their own, to address goals of care. Finally, some providers expressed concern that palliative care consultation was only available on weekdays during daytime hours. Automatic consultation based on predetermined criteria was suggested as a way to avoid conflicts with patients and family. Conclusion: Emergency providers identified many benefits to palliative care consultation. Solving logistical problems and developing clear indications for consultation might help increase the use of such services. © 2012 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved. Source


Mamudu H.M.,East Tennessee State University | Veeranki S.P.,Vanderbilt University | John R.M.,Research Consultant
Nicotine and Tobacco Research | Year: 2013

To assess tobacco use among school-going adolescents and delineate determinants of their tobacco-use status. The study utilizes Global Youth Tobacco Survey data collected in 2006 (9,990 unweighted; 773,982 weighted). Univariate and bivariate analyses were performed to determine the relationship between the dependent (tobacco-use status) and independent variables. Logistic regression analyses were conducted to identify the key determinants of tobacco use among adolescents in Ghana. The gap in tobacco use between males and females was narrow (6.7% vs. 4.4% for ever cigarette smoker; 2.4% vs. 1.4% for current cigarette smoker; 6.8% vs. 5.2% for user of noncigarette tobacco products). Youth tobacco use was significantly associated with exposure to tobacco industry promotions and tobacco-use behavior of familial relations. Conversely, knowledge about the harmful effects of secondhand smoke was associated with decreased likelihood of tobacco use; however, it was significant only for users of noncigarette tobacco products. The narrow gap in tobacco use among school-going adolescents in a country where tobacco-use prevalence among adult males is more than 10 times that of females is a major policy concern. Additionally, the finding that about 15% of students have either acquired tobacco-branded merchandise or been offered a free cigarette suggest that tobacco marketing is reaching adolescents in the country, which demands urgent policy response. Dealing with such problems requires a comprehensive ban on tobacco industry advertising and promotion and marketing strategies, and policies that restrict youth access to and demand for tobacco products. © The Author 2013. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. Source


Hamid A.-K.,University of Sharjah | Cooray F.R.,Research Consultant
AEU - International Journal of Electronics and Communications | Year: 2014

An exact analytic solution to the problem of scattering of a plane electromagnetic wave from a chirally coated elliptic cylinder defined by a DB boundary has been obtained, by expanding the different electromagnetic fields associated with the problem in terms of suitable elliptic vector wave functions and a set of expansion coefficients. The incident field expansion coefficients are known, but the expansion coefficients associated with the fields scattered outside the coated cylinder and the fields transmitted inside the coating are unknown. These unknown coefficients are obtained by imposing appropriate boundary conditions at the two boundaries. Results have been presented as normalized bistatic and backscattering widths for a variety of admittances, permeabilities, and permittivities of the chiral materials used for the coating, to show their effects on scattering from the chirally coated cylinder. © 2014 Elsevier GmbH. All rights reserved. Source

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