Orientation filtering by growth-velocity competition in zone-melting recrystallization of silicon on SiO_2

We describe a method of controlling the in-plane directions of grains in (100)-textured silicon films produced by zone-melting recrystallization over amorphous SiO2. Grains having in-plane orientation within a narrow range are able to grow through an orientation filter consisting of a pattern of crystallization barriers, while grains having other orientations are occluded. The results of experiments using an orientation filter, and the parameters which optimize filter performance, are reported

Stressed detector arrays for airborne astronomy

The development of stressed Ge:Ga detector arrays for far-infrared astronomy from the Kuiper Airborne Observatory (KAO) is discussed. Researchers successfully constructed and used a three channel detector array on five flights from the KAO, and have conducted laboratory tests of a two-dimensional, 25 elements (5x5) detector array. Each element of the three element array performs as well as the researchers' best single channel detector, as do the tested elements of the 25 channel system. Some of the exciting new science possible with far-infrared detector arrays is also discussed

The focused ion beam as an integrated circuit restructuring tool

One of the capabilities of focused ion beam systems is ion milling. The purpose of this work is to explore this capability as a tool for integrated circuit restructuring. Methods for cutting and joining conductors are needed. Two methods for joining conductors are demonstrated. The first consists of spinning nitrocellulose (a self‐developing resist) on the circuit, ion exposing an area, say, 7×7 μm, then milling a smaller via with sloping sidewalls through the first metal layer down to the second, e‐beam evaporating metal, and then dissolving the nitrocellulose to achieve liftoff. The resistance of these links between two metal levels varied from 1 to 7 Ω. The second, simpler method consists of milling a via with vertical sidewalls down to the lower metal layer, then reducing the milling scan to a smaller area in the center of this via, thereby redepositing the metal from the lower layer on the vertical sidewall. The short circuit thus achieved varied from 0.4 to 1.5 Ω for vias of dimensions 3×3 μm to 1×1 μm, respectively. The time to mill a 1×1 μm via with a 68 keV Ga+ beam, of 220 Pa current is 60 s. In a system optimized for this application, this milling time is expected to be reduced by a factor of at least 100. In addition, cuts have been made in 1‐μm‐thick Al films covered by 0.65 μm of SiO2. These cuts have resistances in excess of 20 MΩ. This method of circuit restructuring can work at dimensions a factor of 10 smaller than laser zapping and requires no special sites to be fabricated

Quantum suppression of shot noise in field emitters

We have analyzed the shot noise of electron emission under strong applied electric fields within the Landauer-Buttiker scheme. In contrast to the previous studies of vacuum-tube emitters, we show that in new generation electron emitters, scaled down to the nanometer dimensions, shot noise much smaller than the Schottky noise is observable. Carbon nanotube field emitters are among possible candidates to observe the effect of shot-noise suppression caused by quantum partitioning.Comment: 5 pages, 1 fig, minor changes, published versio

Rapid and Precise Semi-Automatic Axon Quantification in Human Peripheral Nerves

We developed a time-efficient semi-automated axon quantification method using freeware in human cranial nerve sections stained with paraphenylenediamine (PPD). It was used to analyze a total of 1238 facial and masseteric nerve biopsies. The technique was validated by comparing manual and semi-automated quantification of 129 (10.4%) randomly selected biopsies. The software-based method demonstrated a sensitivity of 94% and a specificity of 87%. Semi-automatic axon counting was significantly faster (p<0.001) than manual counting. It took 1hour and 47minutes for all 129 biopsies (averaging 50sec per biopsy, 0.04seconds per axon). The counting process is automatic and does not need to be supervised. Manual counting took 21hours and 6minutes in total (average 9minutes and 49seconds per biopsy, 0.52seconds per axon). Our method showed a linear correlation to the manual counts (R=0.944 Spearman rho). Attempts have been made by several research groups to automate axonal load quantification. These methods often require specific hard- and software and are therefore only accessible to a few specialized laboratories. Our semi-automated axon quantification is precise, reliable and time-sparing using publicly available software and should be useful for an effective axon quantification in various human peripheral nerves

China’s emerging global role: dissatisfied responsible great power

China has (re)emerged as a great power in a world not of its own making. The distribution of power in major organisations and the dominant norms of international interactions are deemed to unfairly favour the existing Western powers, and at times obstruct China’s ability to meet national development goals. Nevertheless, engaging the global economy has been a key source of economic growth (thus helping to maintain regime stability), and establishing China’s credentials as a responsible global actor is seen as a means of ensuring continued access to what China needs. As an emerging great power that is also still in many respects a developing country, China’s challenge is to change the global order in ways that do not cause global instability or generate crises that would damage China’s own ability to generate economic growth and ensure political stability

The Charge Form Factor of the Neutron at Low Momentum Transfer from the 2H⃗(e⃗,e′n)p^{2}\vec{\rm H}(\vec{\rm e},{\rm e}'{\rm n}){\rm p} Reaction

We report new measurements of the neutron charge form factor at low momentum transfer using quasielastic electrodisintegration of the deuteron. Longitudinally polarized electrons at an energy of 850 MeV were scattered from an isotopically pure, highly polarized deuterium gas target. The scattered electrons and coincident neutrons were measured by the Bates Large Acceptance Spectrometer Toroid (BLAST) detector. The neutron form factor ratio $G^{n}_{E}/G^{n}_{M}$ was extracted from the beam-target vector asymmetry $A_{ed}^{V}$ at four-momentum transfers $Q^{2}=0.14$, 0.20, 0.29 and 0.42 (GeV/c)$^{2}$.Comment: 5 pages, 3 figures, submitted to Phys. Rev. Let

Measurement of the proton electric to magnetic form factor ratio from \vec ^1H(\vec e, e'p)

We report the first precision measurement of the proton electric to magnetic form factor ratio from spin-dependent elastic scattering of longitudinally polarized electrons from a polarized hydrogen internal gas target. The measurement was performed at the MIT-Bates South Hall Ring over a range of four-momentum transfer squared $Q^2$ from 0.15 to 0.65 (GeV/c)$^2$. Significantly improved results on the proton electric and magnetic form factors are obtained in combination with previous cross-section data on elastic electron-proton scattering in the same $Q^2$ region.Comment: 4 pages, 2 figures, submitted to PR