39,433 research outputs found
Metallization of Vias in Silicon Wafers to Produce Three-Dimensional Microstructures
The processes of electrochemical deposition into a matrix of vertical vias of different diameters
(500–2000 nm) in Si/SiO2 substrates with a TiN barrier layer at the bottom of the holes are studied. Morpho-
logical studies of the metal in the holes show that the structure of copper clusters is rather uniform and is
formed from crystallites of ~30 to 50 nm. Repeatability and stability with a homogeneous structure and with
holes filled 100% by Cu determine the prospect of using the Si/SiO2/Cu system as a basic element for creating three-dimensional micro- and nanostructures, as well as for the 3D assembly of IC crystals
Two- and Three-dimensional High Performance, Patterned Overlay Multi-chip Module Technology
A two- and three-dimensional multi-chip module technology was developed in response to the continuum in demand for increased performance in electronic systems, as well as the desire to reduce the size, weight, and power of space systems. Though developed to satisfy the needs of military programs, such as the Strategic Defense Initiative Organization, the technology, referred to as High Density Interconnect, can also be advantageously exploited for a wide variety of commercial applications, ranging from computer workstations to instrumentation and microwave telecommunications. The robustness of the technology, as well as its high performance, make this generality in application possible. More encouraging is the possibility of this technology for achieving low cost through high volume usage
NBursts: Simultaneous Extraction of Internal Kinematics and Parametrized SFH from Integrated Light Spectra
We present a novel approach for simultaneous extraction of stellar population
parameters and internal kinematics from the spectra integrated along a line of
sight. We fit a template spectrum into an observed one in a pixel space using a
non-linear minimization in the multidimensional parameter space,
including characteristics of the line-of-sight velocity distribution (LOSVD)
and parametrized star formation history (SFH). Our technique has been applied
to IFU and multi-object spectroscopy of low-luminosity early type galaxies.Comment: 2 pages, to appear in the proceedings of IAU Symposium 241 (Stellar
Populations as Building Blocks of Galaxies
Experimental study of optimal measurements for quantum state tomography
Quantum tomography is a critically important tool to evaluate quantum
hardware, making it essential to develop optimized measurement strategies that
are both accurate and efficient. We compare a variety of strategies using
nearly pure test states. Those that are informationally complete for all states
are found to be accurate and reliable even in the presence of errors in the
measurements themselves, while those designed to be complete only for pure
states are far more efficient but highly sensitive to such errors. Our results
highlight the unavoidable tradeoffs inherent to quantum tomography.Comment: 5 pages, 3 figure
Smith-Purcell Radiation from Low-Energy Electrons
Recent advances in the fabrication of nanostructures and nanoscale features
in metasurfaces offer a new prospect for generating visible, light emission
from low energy electrons. In this paper, we present the experimental
observation of visible light emission from low-energy free electrons
interacting with nanoscale periodic surfaces through the Smith-Purcell (SP)
effect. SP radiation is emitted when electrons pass in close proximity over a
periodic structure, inducing collective charge motion or dipole excitations
near the surface, thereby giving rise to electromagnetic radiation. We
demonstrate a controlled emission of SP light from nanoscale gold gratings with
periodicity as small as 50 nm, enabling the observation of visible SP radiation
by low energy electrons (1.5 to 6 keV), an order of magnitude lower than
previously reported. We study the emission wavelength and intensity dependence
on the grating pitch and electron energy, showing agreement between experiment
and theory. Further reduction of structure periodicity should enable the
production of SP-based devices that operate with even slower electrons that
allow an even smaller footprint and facilitate the investigation of quantum
effects for light generation in nanoscale devices. A tunable light source
integrated in an electron microscope would enable the development of novel
electron-optical correlated spectroscopic techniques, with additional
applications ranging from biological imaging to solid-state lighting.Comment: 16 pages, 4 figure
ICCAD 2015 Contest in 3D Interlayer Cooling Optimized Network
Microchannel liquid cooling has been proposed since the late 2000s as a viable enabler for 3D integration of microprocessors to continue scaling of computing power in the face of increasingly reduced returns from CMOS technology scaling. Thermal and electrical demonstrations of microchannel liquid-cooled heat sinks on the back side of IC dies exist in the literature and the compatibility of its fabrication with the existing CMOS process has been shown. This compatibility also gives rise to the prospect of building of nearly an infinite variety of channel networks with no additional manufacturing cost. This ICCAD 2015 problem aims to identify methods to optimize such microchannel fluid networks, and to evaluate impact of different cooling networks on different computing architectures floorplans
Limits on Fundamental Limits to Computation
An indispensable part of our lives, computing has also become essential to
industries and governments. Steady improvements in computer hardware have been
supported by periodic doubling of transistor densities in integrated circuits
over the last fifty years. Such Moore scaling now requires increasingly heroic
efforts, stimulating research in alternative hardware and stirring controversy.
To help evaluate emerging technologies and enrich our understanding of
integrated-circuit scaling, we review fundamental limits to computation: in
manufacturing, energy, physical space, design and verification effort, and
algorithms. To outline what is achievable in principle and in practice, we
recall how some limits were circumvented, compare loose and tight limits. We
also point out that engineering difficulties encountered by emerging
technologies may indicate yet-unknown limits.Comment: 15 pages, 4 figures, 1 tabl
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Assessment of carotid atherosclerotic disease using three-dimensional cardiovascular magnetic resonance vessel wall imaging: comparison with digital subtraction angiography.
BACKGROUND:A three-dimensional (3D) cardiovascular magnetic resonance (CMR) vessel wall imaging (VWI) technique based on 3D T1 weighted (T1w) Sampling Perfection with Application-optimized Contrast using different flip angle Evolutions (SPACE) has recently been used as a promising CMR imaging modality for evaluating extra-cranial and intra-cranial vessel walls. However, this technique is yet to be validated against the current diagnostic imaging standard. We therefore aimed to evaluate the diagnostic performance of 3D CMR VWI in characterizing carotid disease using intra-arterial digital subtraction angiography (DSA) as a reference. METHODS:Consecutive patients with at least unilateral > 50% carotid stenosis on ultrasound were scheduled to undergo interventional therapy were invited to participate. The following metrics were measured using 3D CMR VWI and DSA: lumen diameter of the common carotid artery (CCA) and segments C1-C7, stenosis diameter, reference diameter, lesion length, stenosis degree, and ulceration. We assessed the diagnostic sensitivity, specificity, accuracy, and receiver operating characteristic (ROC) curve of 3D CMR VWI, and used Cohen's kappa, the intraclass correlation coefficient (ICC), and Bland-Altman analyses to assess the diagnostic agreement between 3D CMR VWI and DSA. RESULTS:The ICC (all ICCs ≥0.96) and Bland-Altman plots indicated excellent inter-reader agreement in all individual morphologic measurements by 3D CMR VWI. Excellent agreement in all individual morphologic measurements were also found between 3D CMR VWI and DSA. In addition, 3D CMR VWI had high sensitivity (98.4, 97.4, 80.0, 100.0%), specificity (100.0, 94.5, 99.1, 98.0%), and Cohen's kappa (0.99, 0.89, 0.84, 0.96) for detecting stenosis > 50%, stenosis > 70%, ulceration, and total occlusion, respectively, using DSA as the standard. The AUC of 3D CMR VWI for predicting stenosis > 50 and > 70% were 0.998 and 0.999, respectively. CONCLUSIONS:The 3D CMR VWI technique enables accurate diagnosis and luminal feature assessment of carotid artery atherosclerosis, suggesting that this imaging modality may be useful for routine imaging workups and provide comprehensive information for both the vessel wall and lumen
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