6,259 research outputs found
Nanotrench for nano and microparticle electrical interconnects
We present a simple and versatile patterning procedure for the reliable and reproducible fabrication of high aspect ratio (10 4 ) electrical interconnects that have separation distances down to 20 nm and lengths of several hundreds of microns. The process uses standard optical lithography techniques and allows parallel processing of many junctions, making it easily scalable and industrially relevant. We demonstrate the suitability of these nanotrenches as electrical interconnects for addressing micro and nanoparticles by realizing several circuits with integrated species. Furthermore, low impedance metal-metal low contacts are shown to be obtained when trapping a single metal-coated microsphere in the gap, emphasizing the intrinsic good electrical conductivity of the interconnects, even though a wet process is used. Highly resistive magnetite-based nanoparticles networks also demonstrate the advantage of the high aspect ratio of the nanotrenches for providing access to electrical properties of highly resistive materials, with leakage current levels below 1 pA. © 2010 IOP Publishing Ltd
The use and effectiveness of the eLib subject gateways: a preliminary investigation
Internet subject gateways were set up under the Electronic Libraries Programme (eLib) in order to address some of the problems of searching the Internet which have been identified by information professionals, i.e. locating relevant, good quality information. This preliminary study examines the extent to which academics in two universities use three eLib subject gateways (EEVL, OMNI and SOSIG). The results are generally encouraging for the eLib programme, but it is necessary for the gateways to be more effectively promoted. The study also found that academics do not have the same misgivings about the general search engines as the information professionals and seem to use them more readily than the gateways
Quantum Symmetries and Strong Haagerup Inequalities
In this paper, we consider families of operators in
a tracial C-probability space , whose joint
-distribution is invariant under free complexification and the action of
the hyperoctahedral quantum groups . We prove a strong
form of Haagerup's inequality for the non-self-adjoint operator algebra
generated by , which generalizes the
strong Haagerup inequalities for -free R-diagonal families obtained by
Kemp-Speicher \cite{KeSp}. As an application of our result, we show that
always has the metric approximation property (MAP). We also apply
our techniques to study the reduced C-algebra of the free unitary
quantum group . We show that the non-self-adjoint subalgebra generated by the matrix elements of the fundamental corepresentation of
has the MAP. Additionally, we prove a strong Haagerup inequality for
, which improves on the estimates given by Vergnioux's property
RD \cite{Ve}
The Dwarf Novae of Shortest Period
We present observations of the dwarf novae GW Lib, V844 Her, and DI UMa.
Radial velocities of H-alph yield orbital periods of 0.05332 +- 0.00002 d (=
76.78 m) for GW Lib and and 0.054643 +- 0.000007 d (= 78.69 m) for V844 Her.
Recently, the orbital period of DI UMa was found to be only 0.054564 +-
0.000002 d (= 78.57 m) by Fried et al. (1999), so these are the three shortest
orbital periods among dwarf novae with normal-abundance secondaries.
GW Lib has attracted attention as a cataclysmic binary showing apparent ZZ
Ceti-type pulsations of the white dwarf primary. Its spectrum shows sharp
Balmer emission flanked by strong, broad Balmer absorption, indicating a
dominant contribution by white-dwarf light. Analysis of the Balmer absorption
profiles is complicated by the unknown residual accretion luminosity and lack
of coverage of the high Balmer lines. Our best-fit model atmospheres are
marginally hotter than the ZZ Ceti instability strip, in rough agreement with
recent ultraviolet results from HST. The spectrum and outburst behavior of GW
Lib make it a near twin of WZ Sge, and we estimate it to have a quiescent V
absolute magnitude 12. Comparison with archival data reveals proper motion of
65 +- 12 mas/yr.
The mean spectrum of V844 Her is typical of SU UMa dwarf novae. We detected
superhumps in the 1997 May superoutburst with superhump period = 0.05597 +-
0.00005 d. The spectrum of DI UMa appears normal for a dwarf nova near minimum
light.
These three dwarf novae have nearly identical short periods but completely
dissimilar outburst characteristics. We discuss possible implications.Comment: Accepted for publication in Publications of the Astronomical Society
of the Pacific; 16 pages, 6 figure
A Catalog of Architectural Tactics for Cyber-Foraging
Mobile devices have become for many the preferred way of interacting with the Internet, social media and the enterprise. However, mobile devices still do not have the computing power or battery life that will allow them to perform effectively over long periods of time or for executing applications that require extensive communication or computation, or low latency. Cyber-foraging is a technique enabling mobile devices to extend their computing power and storage by offloading computation or data to more powerful servers located in the cloud or in single-hop proximity. This paper presents a catalog of architectural tactics for cyber-foraging that was derived from the results of a systematic literature review on architectures for cyber-foraging systems. Elements of the architectures identified in the primary studies were codified in the form of Architectural Tactics for Cyber-Foraging. These tactics will help architects extend their design reasoning towards cyber-foraging as a way to support the mobile applications of the present and the future
Solution-processable, niobium-doped titanium oxide nanorods for application in low-voltage, large-area electronic devices
We report for the first time the one-step synthesis of solution-processable, highly crystalline, niobiumdoped titanium dioxide (Nb-TiO2) nanorods in the anatase phase by the hydrolytic condensation of Ti(OiPr)4 and niobium(V) ethoxide using oleic acid as a structure-directing and stabilising agent. These novel surface-stabilised nanorods can be easily dispersed in common solvents at relatively high concentration (B10%) and deposited as uniform, thin and transparent films on planar substrates for the fabrication of electronic devices. The small size of the nanoparticles synthesized represents an important advance in achieving high-k dielectric thin films smooth enough to be suitable for OFET applications and the plastic electronics filed in general. Preliminary investigations show that the dielectric constant, k, of niobium-doped (7.1 wt%) titanium dioxide (Nb-TiO2) nanorods at frequencies in the region of 100 kHzâ1 MHz, are more a third greater (k 4 8) than that (k = 6) determined for the corresponding undoped titanium dioxide (TiO2) nanorods. The currentâvoltage (JâV) behaviour of these devices reveal that niobium-doping improves, by reducing, the leakage current of these devices, thereby preventing hard dielectric breakdown of devices incorporating these new nanorods
Superhumps in Cataclysmic Binaries. XXII. 1RXS J232953.9+062814
We report photometry of 1RXS J232953.9+062814, a recently discovered dwarf
nova with a remarkably short 64.2-minute orbital period. In quiescence, the
star's light curve is that of a double sinusoid, arising from the "ellipsoidal"
distortion of the Roche-lobe-filling secondary. During superoutburst, common
superhumps develop with a period 3-4% longer than P_orb. This indicates a mass
ratio M_2/M_1=0.19+-0.02, a surprisingly large value in so compact a binary.
This implies that the secondary star has a density 2-3 times higher than that
of other short-period dwarf novae, suggesting a secondary enriched by H-burning
prior to the common-envelope phase of evolution. We estimate i=50+-5 deg,
M_1=0.63 (+0.12, -0.09) M_sol, M_2=0.12 (+0.03, -0.02) M_sol, R_2=0.121
(+0.010, -0.007) R_sol, and a distance to the binary of 180+-40 pc.Comment: PDF, 17 pages, 3 tables, 5 figures; accepted, in press, to appear
June 2002, PASP; more info at http://cba.phys.columbia.edu
- âŠ