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.

A Constitutive Description of Nonlinear Metamaterials Through Electric, Magnetic, and Magnetoelectric Nonlinearities

Abstract: Nonlinear metamaterials provide a host of interesting phenomena which, like for their linear counterpart, can be described using homogenized, effective properties. Following the convention used in nonlinear optics, the response of nonlinear metamaterials can be expressed as a power series of the incident fields. However, contrarily to most materials used in nonlinear optics that only possess an electric nonlinear response, nonlinear metamaterials often show electric, magnetic, and magneto-electric nonlinear responses within a single unit cell. In this chapter, we present two complementary approaches to determine all the effective nonlinear susceptibilities of nonlinear metamaterials. First we present a coupled-mode theory that provides insight into the origin of the various nonlinear susceptibilities that arise in nonlinear metamaterials according to the symmetry of the unit cell. This approach also leads to a description of the effect of the finite size of the unit cells, often called spatial dispersion. Second, we present a retrieval approach based on transfer matrices that can be used to determine the effective nonlinear susceptibilities from either simulated or experimental results. We finally demonstrate how to use this approach by applying it to the case of dual-gap varactor-loaded split ring resonators.

Imaging of diffuse objects with dispersive imagers

Abstract: Dispersive imagers measure multiple speckle realizations of the object to be estimated. This poses a challenge for coherent imaging as classically objects are backpropagated and then despeckled. We present initial findings on an intensity based method for estimating the scattering density.

Coherent upconversion of light

Abstract: Embodiments include an apparatus and method. An apparatus includes a metasurface that coherently upconverts light waves having a first frequency f 1 . A substrate forms a first plasmonic surface. A plasmonic nanoparticle forms a second plasmonic surface. A layer of a second-order nonlinear dielectric material is disposed between the first plasmonic surface and the second plasmonic surface. The metasurface has at least three plasmonic resonant modes including a first plasmonic resonant mode having a first frequency f 1 , a second plasmonic resonant mode having a second frequency f 2 , and a third plasmonic resonant mode having a third frequency f 3 that is a sum of the first frequency f 1 and the second frequency f 2 . The apparatus includes a second light propagation path from a source of pumped monochromatic coherent light waves having the second frequency f 2 to the metasurface. A digital image capture device captures the generated light waves having the frequency f 3 .

Development And Evaluation Of An Undergraduate Multidisciplinary Project Activity In Engineering And Design

Abstract: The School of Engineering and Design Multidisciplinary Project (MDP) at Brunel University is a one week long project based activity involving first year undergraduate students from across the School subject areas of Electronic and Computer Engineering, Mechanical Engineering, Civil Engineering and Design. This paper describes the main aims of the MDP and gives an overview of how it has developed over the last four years to become a key part of the engineering undergraduate programme at Brunel University. The paper then presents an in-depth evaluation of the MDP, following the collection of 114 survey responses from students across all four subject areas and all four academic years that have participated in the activity, to assess the impact of the MDP on the student learning experience throughout the period of undergraduate study. The paper also discusses feedback about the MDP obtained from the relevant professional bodies that accredit Brunel University undergraduate engineering programmes, and representatives from the Brunel Placement and Careers Centre, to assess their opinions of the usefulness of the project activity in developing key transferable skills and enhancing the employability of Brunel graduates. The findings of this study will ensure the continued success of the MDP in future academic years and also provide a case study of a large scale multidisciplinary group project teaching activity that may prove useful to those considering or currently developing such activities at other higher education institutions.

Thermal testing results of an electroformed nickel secondary (M2) mirror

Abstract: To support higher-frequency operation, the Large Millimeter Telescope/Gran Telescopio Milimetrico (or LMT/GTM) is replacing its existing monolithic aluminum secondary mirror (M2). The new mirror is a segmented design based on the same electroformed nickel reflector panel technology that is already in use for the primary reflector segments. While the new M2 is lighter and has better surface accuracy than the original mirror, the electroformed panels are more sensitive to high temperatures. During the design phase, concerns were raised over the level of temperature increase that could occur at M2 during daytime observations. Although the panel surface is designed to scatter visible light, the LMT primary mirror is large enough to cause substantial solar heating, even at significant angular separation from the Sun. To address these concerns, the project conducted a series of field tests, within the constraint of having minimum impact on night time observations. The supplier sent two coupon samples of a reflector panel prepared identically to their proposed M2 surface. Temperature sensors were mounted on the samples and they were temporarily secured to the existing M2 mirror at different distances from the center. The goal was to obtain direct monitoring of the surface temperature under site thermal conditions and the concentration effects from the primary reflector. With the sensors installed, the telescope was then commanded to track the Sun with an elevation offset. Initially, elevation offsets from as far as 40 degrees to as close as 6 degrees were tested. The 6 degree separation test quickly passed the target maximum temperature and the telescope was returned to a safer separation. Based on these initial results, a second set of tests was performed using elevation separations from 30 degrees to 8 degrees. To account for the variability of site conditions, the temperature data were analyzed using multiple metrics. These metrics included maximum temperature, final time average temperature, and an curve fit for heating/ cooling. The results indicate that a solar separation angle of 20 degrees should be suitable for full performance operation of the LMT/GTM. This separation not only is sufficient to avoid high temperatures at the mirror, but also provides time to respond to any emergency conditions that could occur (e.g., switching to a generator after a power failure) for observations that are ahead of the motion of the Sun. Additionally, even approaches of 10 to 15 degrees of angular separation on the sky may be achievable for longer wavelength observations, though these would likely be limited to positions that are behind the position of the Sun along its motion.

I and i

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 …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

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。

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

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

Surface plasmon subwavelength optics

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.

Phd by thesis

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