49,765 research outputs found
A Two-Step Etching Method to Fabricate Nanopores in Silicon
A cost effectively method to fabricate nanopores in silicon by only using the
conventional wet-etching technique is developed in this research. The main
concept of the proposed method is a two-step etching process, including a
premier double-sided wet etching and a succeeding track-etching. A special
fixture is designed to hold the pre-etched silicon wafer inside it such that
the track-etching can be effectively carried out. An electrochemical system is
employed to detect and record the ion diffusion current once the pre-etched
cavities are etched into a through nanopore. Experimental results indicate that
the proposed method can cost effectively fabricate nanopores in silicon.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
OPERA superluminal neutrinos and Kinematics in Finsler spacetime
The OPERA collaboration recently reported that muon neutrinos could be
superluminal. More recently, Cohen and Glashow pointed that such superluminal
neutrinos would be suppressed since they lose their energies rapidly via
bremsstrahlung. In this Letter, we propose that Finslerian nature of spacetime
could account for the superluminal phenomena of particles. The Finsler
spacetime permits the existence of superluminal behavior of particles while the
casuality still holds. A new dispersion relation is obtained in a class of
Finsler spacetime. It is shown that the superluminal speed is linearly
dependent on the energy per unit mass of the particle. We find that such a
superluminal speed formula is consistent with data of OPERA, MINOS and
Fermilab-1979 neutrino experiments as well as observations on neutrinos from
SN1987a.Comment: 10 pages, 2 figures. Viewpoints of Finslerian special relativity on
OPERA superluminal neutrino
Proposal of Direct Search for Strongly Bound States of ppbar, npbar Systems with High Intensity and Collective pbar beam
In this letter, we discuss the possibility to look for the direct evidence of
the existence of the ppbar and npbar bound states. Measurement of the single
\gamma ray from the ppbar and npbar systems at rest can directly confirm
whether the X(1860) and X(1835) are the resonances which are strongly coupled
to ppbar. In addition to the neutral candidate, a charged resonance is
also proposed to be searched for in npbar channel. We find that the data from
the Crystal Barrel experiment at LEAR/CERN can be used to confirm the X(1835)
observed by BES Collaboration. The possibility of measuring the
spectrum below 100 MeV at the new experiment with cold high intensity \pbar
beam at GSI is discussed. These new techniques can be used to probe the
structure of the X(1860) and X(1835) in the future.Comment: Accepted by Mod. Phys. Lett.
The impact of satellite temperature soundings on the forecasts of a small national meteorological service
The impact of introducing satellite temperature sounding data on a numerical weather prediction model of a national weather service is evaluated. A dry five level, primitive equation model which covers most of the Northern Hemisphere, is used for these experiments. Series of parallel forecast runs out to 48 hours are made with three different sets of initial conditions: (1) NOSAT runs, only conventional surface and upper air observations are used; (2) SAT runs, satellite soundings are added to the conventional data over oceanic regions and North Africa; and (3) ALLSAT runs, the conventional upper air observations are replaced by satellite soundings over the entire model domain. The impact on the forecasts is evaluated by three verification methods: the RMS errors in sea level pressure forecasts, systematic errors in sea level pressure forecasts, and errors in subjective forecasts of significant weather elements for a selected portion of the model domain. For the relatively short range of the present forecasts, the major beneficial impacts on the sea level pressure forecasts are found precisely in those areas where the satellite sounding are inserted and where conventional upper air observations are sparse. The RMS and systematic errors are reduced in these regions. The subjective forecasts of significant weather elements are improved with the use of the satellite data. It is found that the ALLSAT forecasts are of a quality comparable to the SAR forecasts
Geology and mineralization of the Mt Carbine Tungsten Deposit, Northern Queensland, Australia
The Mt Carbine quartz-wolframite-scheelite sheeted vein deposit is located ~80 km NW of Cairns, Northern Queensland. It was the largest vein type W deposit in Australia and accounted for 43% of Australia’s annual W production in 1986, prior to closure because of international Sn-W market crash. The hard rock resources at Mt Carbine include indicated resources of 18 Mt at 0.14% WO3 and inferred resources of 29.3 Mt at 0.12% WO3 (Carbine Tungsten Limited Annual Report 2014). The vein system in Mt Carbine is hosted in Ordovician to Devonian Hodgkinson Formation metasedimentary rocks, which include turbiditic metasediments composed mainly of greywacke, siltstone-shale, slate, basalt, conglomerates and chert. There are four 30-40 m wide vein zones in the open pit with different orientations, with Zones 1 - 3 being ~300°/80° (strike/dip) with dip direction of 210°, 210° and 20°, respectively, and Zone 4 270°/65° with dip direction of 180° to 185°. Based on drill core logging and open pit observation, the paragenesis sequence has been established. Stage 0 is represented by deformed curvy and discontinuous quartz-dominant veins with minor to none W mineralization. Stage I continuous quartz-dominant veins have straight and continuous margin, and are composed of wolframite±scheelite± K-feldspar±biotite±tourmailine±apatite. Stage II veins are straight & continuous, quartz-dominant with sharp boundaries, and contain chlorite±scheelite±wolframite± cassiterite±muscovite. Stage III is represented by undeformed straight and continuous quartz±chlorite± muscovite±molybdenite±arsenopyrite±chalcopyrite±pyrite±
pyrrhotite±sphalerite veins, without W mineralization. Stage IV veins are featured by the undeformed straight and continuous shape and quartz ± calcite ± fluorite mineralogy without any W mineralization. The W mineralization is mostly in stage II quartz veins, with less economic W mineralization in the other 3 stages of veins. Ore minerals are wolframite and scheelite. Wolframite is typically euhedral and occurs in quartz veins, while the occurrences of scheelite are: (1) euhedral grains in quartz vein and, (2) pseudomorphing wolframite grains or cutting across wolframite grains as veinlets. There are at least 3 felsic igneous rock types in the mining district, including porphyritic biotite granite, equigranular coarse-grained biotite granite and fine-grained felsic dykes that cuts across the ore body. There is no observable contact between granite and the W veins, thus their relationship is unclear. Mineralized quartz veins and chlorite alteration occur in the porphyritic biotite granite, whereas no quartz vein and alteration are present in the fine-grained felsic dyke, indicating that the porphyritic biotite granite was earlier than mineralization and the felsic dyke later than mineralization. This observation is consistent with the latest dating results: the LA-ICP-MS zircon U-Pb age of the porphyritic biotite granite is 298±3 Ma and the felsic dyke 261±7 Ma, whereas the molybdenite Re-Os age from the mineralized quartz vein is 28 ±1 Ma, and the muscovite 40Ar-39Ar ages are 282-277 (±1-2) Ma. There is no overlap between the 2 muscovite 40Ar-39Ar ages, probably indicates there was some post-mineralization tectono-thermal activities. Preliminary fluid inclusion studies reveal that most of them are primary, with sizes up to 26 μm. The homogenization temperatures range from 210 to 290°C, final ice-melting temperatures are between 0 and −3.7°C. Laser Raman analysis identified CH4 in the vapor bubble. The δ34S values of sulphides range from -9.1 to -6.0‰, and O-H isotopes largely overlap with metamorphic water
Nodeless superconductivity and preserved time-reversal symmetry in the noncentrosymmetric Mo3P superconductor
We report a comprehensive study of the noncentrosymmetric superconductor
MoP. Its bulk superconductivity, with K, was characterized via
electrical resistivity, magnetization, and heat-capacity measurements, while
its microscopic electronic properties were investigated by means of muon-spin
rotation/relaxation (SR) and nuclear magnetic resonance (NMR) techniques.
In the normal state, NMR relaxation data indicate an almost ideal metallic
behavior, confirmed by band-structure calculations, which suggest a relatively
high electron density of states, dominated by the Mo -orbitals. The
low-temperature superfluid density, determined via transverse-field SR and
electronic specific heat, suggest a fully-gapped superconducting state in
MoP, with meV, the same as the BCS gap value in the
weak-coupling case, and a zero-temperature magnetic penetration depth
nm. The absence of spontaneous magnetic fields below the
onset of superconductivity, as determined from zero-field SR measurements,
indicates a preserved time-reversal symmetry in the superconducting state of
MoP and, hence, spin-singlet pairing.Comment: 13 pages, 16 figures, accepted by Phys. Rev.
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