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Huntsville, AL, United States

Lihh W.-S.,Research South, Inc.
IEEE Transactions on Antennas and Propagation | Year: 2010

When asymptotically describing the wave fields on the denser side of a planar permittivity interface, the canonical head-wave fields of the tangential-magnetic (TM) set show discrepancies with the full-wave fields. This paper derives the correction fields that supplement the canonical TM head-wave fields, by taking into account the proximity between the head-wave branch point and an extraneous pole in the wavenumber domain. The validity of the correction is demonstrated in the time domain by comparing the waveforms of a corrected field and the full-wave field, for various ratios of permittivity and at various locations of observation. Consideration is also given to the case of a conducting medium. © 2010 IEEE.

Clement A.F.,University College London | Hillson S.W.,University College London | Aiello L.C.,Research South, Inc.
Journal of Human Evolution | Year: 2012

The Anterior Dental Loading Hypothesis states that the unique Neanderthal facial and dental anatomy was an adaptive response to the regular application of heavy forces resulting from both the masticatory and cultural use of the anterior teeth. Heavy anterior tooth wear frequently observed in Neanderthal specimens is cited as a main source of evidence for heavy forces being applied to these teeth. From this, it might be predicted that the wear shown on the anterior teeth of Neanderthals would greatly exceed that of the posterior teeth and that this differential would be greater than in other hominins with different facial morphologies.In this paper, a new method of examining tooth wear patterns is used to test these predictions in a large assemblage of Late Pleistocene hominins and a group of recent hunter-gatherers from Igloolik, Canada. The results show that all Late Pleistocene hominins, including Neanderthals, had heavily worn anterior teeth relative to their posterior teeth but, contrary to expectations, this was more pronounced in the modern humans than in the Neanderthals. The Igloolik Inuit showed heavier anterior tooth wear relative to their posterior teeth than any Late Pleistocene hominins. There was, however, a characteristic Neanderthal pattern in which wear was more evenly spread between anterior teeth than in modern humans. Overall, the evidence presented here suggests that all Late Pleistocene hominins habitually applied heavy forces between their anterior teeth and that Neanderthals were not exceptional in this regard. These results therefore does not support the Anterior Dental Loading Hypothesis. © 2012 Elsevier Ltd.

Kim D.S.,Research South, Inc.
Human Vaccines and Immunotherapeutics | Year: 2013

The 13th annual World Vaccine Congress held in Washington DC (April 16-18, 2013) sponsored a plenary and a session focused on cancer vaccine. The cancer vaccine session consisted of three presentations: "Cancer vaccine landscape overview" by Dr Jeffrey Schlom, a Chief of the Laboratory of Tumor Immunology and Biology, Center for Cancer Research (CCR), National Cancer Institute (NCI); "Immune-system based cancer vaccines" by Dr Geert-Jan Boons, the Complex Carbohydrate Research Center of the University of Georgia; "Peptide vaccine for malignant gliomas" by Dr Robert Fenstermaker, Chair of the Department of Neurosurgery at Roswell Park Cancer Institute. As Dr Jay Berzofsky, Chief of the new Vaccine Branch (CCR, NCI) pointed out in the plenary, not only the quantity but also the quality (avidity and longevity)1 of T cell activation is important for the clearance of cancer cells, each of the presented cancer vaccine platforms will first be reviewed by its immunological design to promote the activation of T cells. Then, the benefits of combined cancer vaccines therapy with conventional cancer therapy will be discussed with a mathematical model from NCI prostate cancer trials. © 2013 Landes Bioscience.

Lee S.,Research South, Inc. | Park J.,Seoul National University of Science and Technology | Choi S.,Seoul National University of Science and Technology
IEEE Transactions on Power Electronics | Year: 2011

In this paper, a new active-clamped three-phase current-fed push-pull dc-dc converter is proposed for high-power applications where low-voltage high-current input sources such as fuel cells are used. The proposed converter has the following features: active clamping of the transient surge voltage caused by transformer leakage inductances, natural zero-voltage switching turn-on of main switches using energy stored in transformer leakage inductor, small current rating and zero-voltage and zero-current switching of clamp switches, no additional start-up circuitry for soft starting due to the operating duty cycle range between 0 and 1, and zero-current switching turn-off of rectifier diodes leading to negligible voltage surge associated with the diode reverse recovery. A comparative study along with loss analysis is performed. Experimental results from 5-kW laboratory prototypes of the proposed active-clamped converter and the passive-clamped converter are provided. © 2011 IEEE.

Kim D.,Korea Research Institute of Standards and Science | Han J.,Research South, Inc. | Choi Y.,Jeonju University
Analytical and Bioanalytical Chemistry | Year: 2013

A method using on-line solid-phase microextraction (SPME) on a carbowax-templated fiber followed by liquid chromatography (LC) with ultraviolet (UV) detection was developed for the determination of triclosan in environmental water samples. Along with triclosan, other selected phenolic compounds, bisphenol A, and acidic pharmaceuticals were studied. Previous SPME/LC or stir-bar sorptive extraction/LC-UV for polar analytes showed lack of sensitivity. In this study, the calculated octanol-water distribution coefficient (log D) values of the target analytes at different pH values were used to estimate polarity of the analytes. The lack of sensitivity observed in earlier studies is identified as a lack of desorption by strong polar-polar interactions between analyte and solid-phase. Calculated log D values were useful to understand or predict the interaction between analyte and solid phase. Under the optimized conditions, the method detection limit of selected analytes by using on-line SPME-LC-UV method ranged from 5 to 33 ng L-1, except for very polar 3-chlorophenol and 2,4-dichlorophenol which was obscured in wastewater samples by an interfering substance. This level of detection represented a remarkable improvement over the conventional existing methods. The on-line SPME-LC-UV method, which did not require derivatization of analytes, was applied to the determination of TCS including phenolic compounds and acidic pharmaceuticals in tap water and river water and municipal wastewater samples. [Figure not available: see fulltext.] © 2012 Springer-Verlag Berlin Heidelberg.

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