230 research outputs found
Trajectory matching of ozonesondes and MOZAIC measurements in the UTLS – Part 2: Application to the global ozonesonde network
Both balloon-borne electrochemical ozonesondes and MOZAIC (measurements of
ozone, water vapour, carbon monoxide and nitrogen oxides by in-service Airbus
aircraft) provide very valuable data sets for ozone studies in the upper
troposphere/lower stratosphere (UTLS). Although MOZAIC's highly accurate
UV-photometers are regularly inspected and recalibrated annually, recent
analyses cast some doubt on the long-term stability of their ozone analysers.
To investigate this further, we perform a 16 yr comparison (1994–2009) of
UTLS ozone measurements from balloon-borne ozonesondes and MOZAIC. The
analysis uses fully three-dimensional trajectories computed from ERA-Interim
(European Centre for Medium-Range Weather Forecasts Re-analysis) wind fields
to find matches between the two measurement platforms. Although different
sensor types (Brewer-Mast and Electrochemical Concentration Cell ozonesondes)
were used, most of the 28 launch sites considered show considerable
differences of up to 25% compared to MOZAIC in the mid-1990s, followed
by a systematic tendency to smaller differences of around 5–10% in
subsequent years. The reason for the difference before 1998 remains unclear,
but observations from both sondes and MOZAIC require further examination to
be reliable enough for use in robust long-term trend analyses starting before
1998. According to our analysis, ozonesonde measurements at tropopause
altitudes appear to be rather insensitive to changing the type of the
Electrochemical Concentration Cell ozonesonde, provided the cathode sensing
solution strength remains unchanged. Scoresbysund (Greenland) showed
systematically 5% higher readings after changing from Science Pump
Corporation sondes to ENSCI Corporation sondes, while a 1.0% KI cathode
electrolyte was retained
Vanishing Loss Effect on the Effective ac Conductivity behavior for 2D Composite Metal-Dielectric Films At The Percolation Threshold
We study the imaginary part of the effective conductivity as well as its
distribution probability for vanishing losses in 2D composites. This
investigation showed that the effective medium theory provides only
informations about the average conductivity, while its fluctuations which
correspond to the field energy in this limit are neglected by this theory.Comment: 6 pages, 2 figures, submitted to Phys.Rev.
Micro- and nanosystems for biology and medicine
The development of new tools and instruments for biomedical applications based on nano- (NEMS) or microelectromechanical systems technology (MEMS) are bridging the gap between the macro- and the nano-world. The well mastered microtechnique allows controlling many parameters of these instruments, which is essential for conducting reproducible and repeatable experiments in the life sciences. Examples are multifunctional scanning probe sensors for cell biology, an arthroscopic scanning force microscope for minimally invasive medical interventions and a nanopore sensor for single molecule experiments in biochemistry. This paper reviews some of the activities conducted in a fruitful interdisciplinary collaboration between physicists, engineers, biologists and physicians
No Far-Infrared-Spectroscopic Gap in Clean and Dirty High-T Superconductors
We report far infrared transmission measurements on single crystal samples
derived from BiSrCaCuO. The impurity scattering rate of
the samples was varied by electron-beam irradiation, 50MeV O ion
irradiation, heat treatment in vacuum, and Y doping. Although substantial
changes in the infrared spectra were produced, in no case was a feature
observed that could be associated with the superconducting energy gap. These
results all but rule out ``clean limit'' explanations for the absence of the
spectroscopic gap in this material, and provide evidence that the
superconductivity in BiSrCaCuO is gapless.Comment: 4 pages and 3 postscript figures attached. REVTEX v3.0. Accepted for
publication in Phys. Rev. Lett. IRDIRT
Fabrication of nanochannels with PDMS, silicon and glass walls and spontaneous filling by capillary forces
C-axis electronic Raman scattering in Bi_2Sr_2CaCu_2O_{8+\delta}
We report a c-axis-polarized electronic Raman scattering study of
Bi_2Sr_2CaCu_2O_{8+\delta} single crystals. In the normal state, a resonant
electronic continuum extends to 1.5 eV and gains significant intensity as the
incoming photon energy increases. In the superconducting state, a coherence
2\Delta peak appears around 50 meV, with a suppression of the scattering
intensity at frequencies below the peak position. The peak energy, which is
higher than that seen with in-plane polarizations, signifies distinctly
different dynamics of quasiparticle excitations created with out-of-plane
polarization.Comment: 12 pages, REVTEX, 3 postscript figure
Design and Evaluation of a polyimide spring system for the scanning force microscope of the Phoenix Mars Mission 2007
Near-field fluorescence imaging with 32 nm resolution based on microfabricated cantilevered probes
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