1,967 research outputs found
Weighted Low-Regularity Solutions of the KP-I Initial Value Problem
In this paper we establish local well-posedness of the KP-I problem, with
initial data small in the intersection of the natural energy space with the
space of functions which are square integrable when multiplied by the weight y.
The result is proved by the contraction mapping principle. A similar (but
slightly weaker) result was the main Theorem in the paper " Low regularity
solutions for the Kadomstev-Petviashvili I equation " by Colliander, Kenig and
Staffilani (GAFA 13 (2003),737-794 and math.AP/0204244). Ionescu found a
counterexample (included in the present paper) to the main estimate used in the
GAFA paper, which renders incorrect the proof there. The present paper thus
provides a correct proof of a strengthened version of the main result in the
GAFA paper
Helioseismic analysis of the solar flare-induced sunquake of 2005 January 15
We report the discovery of one of the most powerful sunquakes detected to
date, produced by an X1.2-class solar flare in active region 10720 on 2005
January 15. We used helioseismic holography to image the source of seismic
waves emitted into the solar interior from the site of the flare. Acoustic
egression power maps at 3 and 6 mHz with a 2 mHz bandpass reveal a compact
acoustic source strongly correlated with impulsive hard X-ray and
visible-continuum emission along the penumbral neutral line separating the two
major opposing umbrae in the -configuration sunspot that predominates
AR10720. The acoustic emission signatures were directly aligned with both hard
X-ray and visible continuum emission that emanated during the flare. The
visible continuum emission is estimated at J,
approximately 500 times the seismic emission of J. The
flare of 2005 January 15 exhibits the same close spatial alignment between the
sources of the seismic emission and impulsive visible continuum emission as
previous flares, reinforcing the hypothesis that the acoustic emission may be
driven by heating of the low photosphere. However, it is a major exception in
that there was no signature to indicate the inclusion of protons in the
particle beams thought to supply the energy radiated by the flare. The
continued strong coincidence between the sources of seismic emission and
impulsive visible continuum emission in the case of a proton-deficient
white-light flare lends substantial support to the ``back -- warming''
hypothesis, that the low photosphere is significantly heated by intense Balmer
and Paschen continuum-edge radiation from the overlying chromosphere in
white-light flares.Comment: 12 pages, 7 figures, published in MNRA
0-level Vacuum Packaging RT Process for MEMS Resonators
A new Room Temperature (RT) 0-level vacuum package is demonstrated in this
work, using amorphous silicon (aSi) as sacrificial layer and SiO2 as structural
layer. The process is compatible with most of MEMS resonators and Resonant
Suspended-Gate MOSFET [1] fabrication processes. This paper presents a study on
the influence of releasing hole dimensions on the releasing time and hole
clogging. It discusses mass production compatibility in terms of packaging
stress during back-end plastic injection process. The packaging is done at room
temperature making it fully compatible with IC-processed wafers and avoiding
any subsequent degradation of the active devices.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
Does smoking have an influence on postoperative nausea and vomiting?
Background Smoking is considered a risk factor not only for anaesthesia, but for general health. On the other hand, it was demonstrated that smoking reduces postoperative nausea and vomiting. In our study, we have investigated this effect in patients undergoing laparoscopic cholecystectomy. Moreover, we have looked to see if there is a relationship between the number of cigarettes smoked daily and the antiemetic effect. Methods 71 patients scheduled for elective laparoscopic cholecystectomy under general anaesthesia were divided into 2 groups: group 1 (n=40) included non-smokers and group 2 (n=31) included the smokers. Each group was randomized for propofol and thiopentone as an induction agent. In addition, the smokers were further divided into heavy smokers, for patients smoking more than 20 cigarettes daily and smokers for patients smoking less than 20 cigarettes daily. The incidence of postoperative nausea and vomiting and the severity of pain (on Visual Analogue Score) were both assessed for the first 24 hours postoperatively. Results Postoperative nausea and vomiting occurred in 31 patients (77.5%) in the non-smokers’ group, as compared with 12 patients (38.7%) in smokers’ group (
Theory for the phase behaviour of a colloidal fluid with competing interactions
We study the phase behaviour of a fluid composed of particles which interact
via a pair potential that is repulsive for large inter-particle distances, is
attractive at intermediate distances and is strongly repulsive at short
distances (the particles have a hard core). As well as exhibiting gas-liquid
phase separation, this system also exhibits phase transitions from the uniform
fluid phases to modulated inhomogeneous fluid phases. Starting from a
microscopic density functional theory, we develop an order parameter theory for
the phase transition in order to examine in detail the phase behaviour. The
amplitude of the density modulations is the order parameter in our theory. The
theory predicts that the phase transition from the uniform to the modulated
fluid phase can be either first order or second order (continuous). The phase
diagram exhibits two tricritical points, joined to one another by the line of
second order transitions.Comment: 12 pages, 9 figures. Accepted for publication in J. Phys. Condens.
Matte
Gas Geochemistry and Fractionation Processes in Florina Basin, Greece
Florina Basin is located in northern Greece, close to Mount Voras where the volcanic activity of Late Messinian age began. In the area, many CO2-rich gas emissions are present as a bubbling free-phase in groundwater (both springs and wells) and soil gases. Volcanism along with the geological and geodynamic regime of the basin, created the ideal conditions for CO2 accumulation in vertically stacked reservoirs. One of these, industrially exploited by the company Air Liquide Greece, produces 30,000 t/a of CO2. Results show that CO2 concentrations in the gases of Florina can arrive up to 99.8% and are mostly above 90%. Moreover, C-isotope composition (-2.1 to + 0.3 h vs. VPDB) indicates a mixed mantle-limestone origin for CO2, while He isotope composition (R/RA from 0.21 to 1.20) shows a prevailing crustal origin with an up to 15% mantle contribution. Helium and methane, with concentrations spanning over three orders of magnitude, show a positive correlation and a consequent high variability of He/CO2 and CH4/CO2 ratios. This variability can be attributed to the interaction of the uprising gases with groundwater that chemically fractionates them due to their different solubility. Based on the CO2, CH4 and He concentrations, gas samples collected in the basin can be divided in 3 groups: a) deep reservoir gases, b) enriched in less soluble gases and c) depleted in less soluble gases. The first group consists of gas samples collected at the Air Liquide extraction wells, which tap a 300m deep reservoir. This group can be considered as the least affected by fractionation processes due to interaction with groundwater. The gases of the second group due to their interaction with shallower unsaturated aquifers, become progressively enriched in less soluble gases (He and CH4). Finally, the third group represents residual gas phases after extensive degassing of the groundwater during its hydrological pathway
High quality factor copper inductors integrated in deep dry-etched quartz substrates
This paper reports on an inductor fabrication method capable to deliver high quality factor (Q) and high self-resonance frequency (SRF) devices using quartz insulating substrates and thick high-conductivity copper lines. Inductors are key devices in RF circuits that, when fabricated on traditional semiconductor substrates, suffer from poor RF performances due to thin metallization and substrate related losses. Many previous works revealed that RF performances are strongly dependent on the limited metallization thickness and on the conductivity of the substrate. In this paper we demonstrate a new fabrication process to improve the Q factor of spiral inductors by patterning thick high conductive metal layers directly in a dielectric substrate. Moreover, we develop and validate accurate equivalent circuit modeling and parameter extraction for the characterization of the fabricated device
High quality factor copper inductors integrated in deep dry-etched quartz substrates
This paper reports on an inductor fabrication method capable to deliver high quality factor (Q) and high self-resonance frequency (SRF) devices using quartz insulating substrates and thick high-conductivity copper lines. Inductors are key devices in RF circuits that, when fabricated on traditional semiconductor substrates, suffer from poor RF performances due to thin metallization and substrate related losses. Many previous works revealed that RF performances are strongly dependent on the limited metallization thickness and on the conductivity of the substrate. In this paper we demonstrate a new fabrication process to improve the Q factor of spiral inductors by patterning thick high conductive metal layers directly in a dielectric substrate. Moreover, we develop and validate accurate equivalent circuit modeling and parameter extraction for the characterization of the fabricated device
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