scispace - formally typeset
Search or ask a question
Author

David R. Smith

Bio: David R. Smith is an academic researcher from Duke University. The author has contributed to research in topics: Metamaterial & Antenna (radio). The author has an hindex of 110, co-authored 881 publications receiving 91683 citations. Previous affiliations of David R. Smith include Brunel University London & Princeton University.


Papers
More filters
Proceedings ArticleDOI
01 Oct 2013
TL;DR: Two sets of early experimental results for the signal to noise ratio (SNR) and the Q-factor for the RF and FSO simplex link at the far-field distance of RF antenna are presented, demonstrating the functioning transmission capability of the hybrid FSO/RF link employing the proposed antenna.
Abstract: This paper presents a report on experimental set up and results for a hybrid free space optics (FSO)/radio frequency (RF) dual purpose antenna for outdoor applications. The basic design of the antenna is discussed and we present two sets of early experimental results for the signal to noise ratio (SNR) and the Q-factor for the RF and FSO simplex link at the far-field distance of RF antenna, respectively. Over a link span of 15 m the measured SNR and the Q-factor are 45.68 dB and 15.69, respectively, demonstrating the functioning transmission capability of the hybrid FSO/RF link employing the proposed antenna.

6 citations

Proceedings ArticleDOI
17 Oct 2000
TL;DR: In this paper, the status of an experiment to study the neutron spin-electron angular correlation with the Los Alamos Ultra-Cold Neutron (UCN) source is reviewed.
Abstract: This article reviews the status of an experiment to study the neutron spin-electron angular correlation with the Los Alamos Ultra-Cold Neutron (UCN) source. The experiment will generate UCNs from a novel solid deuterium, spallation source, and polarize them in a solenoid magnetic field. The experiment spectrometer will consist of a neutron decay region in a solenoid magnetic field combined with several different detector possibilities. An electron beam and a magnetic spectrometer will provide a precise, absolute calibration for these detectors. An A-correlation measurement with a relative precision of 0.2% is expected by the end of 2002.

6 citations

Proceedings ArticleDOI
01 Aug 2012
TL;DR: In this paper, the effects on the fluorescent emission spectra of commercially produced core-shell (CdSe/ZnS) quantum dots (QDs) were measured following exposure to ∼1 MeV gamma irradiation in the range 0.1-110 Gy.
Abstract: In this work, we report measured effects on the fluorescent emission spectra of commercially produced core-shell (CdSe/ZnS) quantum dots (QDs). We report the effects on the fluorescent emission spectra of commercially produced CdSe/ZnS QDs of 2.5 nm, 3.3 nm and 6.3 nm size in toluene, following exposure to ∼1 MeV gamma irradiation in the range 0.1–110 Gy. We show that damage depends on the size of the QDs and that increasing the concentration of QDs in the toluene decreases the effect. Recent work on the production of a prototype 2D imaging dosimeter, by absorbing a solution of green emitting QD in toluene into a sample of porous “Vycor” glass, has shown that QDs absorbed in the Vycor fluoresce under several hours of continual illumination and that the system continues to show fluorescence for several days after the initial preparation. Initial results of experiments to dynamically image the Vycor during electron irradiation are presented as is progress on the development of a second prototype device for 2D radiation dosimetry.

6 citations

Journal Article
TL;DR: In this paper, a radial gradient-index (GRIN) lens with an index-of-refraction ranging from -2.67 to -0.97 was presented.
Abstract: Metamaterial structures designed to have simultaneously negative permittivity and permeability are known as left-handed materials. Their complexity and our understanding of their properties have advanced rapidly to the point where direct applications are now viable. We present a radial gradient-index (GRIN) lens with an index-of-refraction ranging from -2.67(edge) to -0.97(center). Experimentally, we find the lens can produce field intensities at the focus that are greater than that of the incident plane wave. These results are obtained at 10.45 GHz and in excellent agreement with full-wave simulations. This lens is a demonstrate an newly pioneered advanced fabrication technique using conventional printed circuit board (PCB) technology which offers significant design, mechanical, and cost advantages over other microwave lens constructions.

6 citations

Journal ArticleDOI
TL;DR: This work presents a method based on the electromagnetic variational principle that applies to media that can be described as collections of point dipoles, as most metamaterials are, and demonstrates its efficacy by designing highly efficient, non-perturbative, multiplexing devices.
Abstract: A fundamental challenge has plagued computer-generated volumetric holography since its inception: design methods are available only in the perturbative limit, but this poses serious limitations on efficiency and the amount of multiplexing achievable. Given the recent progress in highly tailorable artificial media, such as metamaterials, the need for general and robust design techniques grows. We present a method based on the electromagnetic variational principle that applies to media that can be described as collections of point dipoles, as most metamaterials are. We demonstrate its efficacy by designing highly efficient, non-perturbative, multiplexing devices.

6 citations


Cited by
More filters
Journal ArticleDOI

[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1(PfPMP1)与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员,通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

18,940 citations

Journal ArticleDOI
TL;DR: A review of gold nanoparticles can be found in this article, where the most stable metal nanoparticles, called gold colloids (AuNPs), have been used for catalysis and biology applications.
Abstract: Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

11,752 citations

Journal ArticleDOI
14 Aug 2003-Nature
TL;DR: By altering the structure of a metal's surface, the properties of surface plasmons—in particular their interaction with light—can be tailored, which could lead to miniaturized photonic circuits with length scales that are much smaller than those currently achieved.
Abstract: Surface plasmons are waves that propagate along the surface of a conductor. By altering the structure of a metal's surface, the properties of surface plasmons--in particular their interaction with light--can be tailored, which offers the potential for developing new types of photonic device. This could lead to miniaturized photonic circuits with length scales that are much smaller than those currently achieved. Surface plasmons are being explored for their potential in subwavelength optics, data storage, light generation, microscopy and bio-photonics.

10,689 citations

Journal ArticleDOI
01 Apr 1988-Nature
TL;DR: In this paper, a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) is presented.
Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

9,929 citations