118 research outputs found
Systems of mutually unbiased Hadamard matrices containing real and complex matrices
We use combinatorial and Fourier analytic arguments
to prove various non-existence results on systems of real and com-
plex unbiased Hadamard matrices. In particular, we prove that
a complete system of complex mutually unbiased Hadamard ma-
trices (MUHs) in any dimension cannot contain more than one
real Hadamard matrix. We also give new proofs of several known
structural results in low dimensions
CORRESPONDENCE BETWEEN GEOMETRIC PROPERTIES OF REAL OBJECTS AND THE HUYNEN PARAMETERS
This paper presents an approach to classify real objects, using polarimetric radar data, on
the basis of the Huynen parameters (HUYNEN, 1970). For this purpose a computer pro-
gram was developed to calculate and display the Huynen parameters from the polarimetric
scattering matrix S, which is measured over a wide frequency range. It is demonstrated
here that the Huynen theory is correct and applicable to electromagnetic inverse scattering
problems to derive target classification operators
Long-term light trap study on the macro-moth (Lepidoptera: Macroheterocera) fauna of the Aggtelek National Park
We analyzed the night-active Macrolepidoptera fauna in the Aggtelek karst region (near the village JĂłsvafĂ”) by Jermy-type light-trap in 1990, 1993 and during 1999â2004. In each year the trap operated from 5 March until 5 November. During the eight years altogether 127 929 specimens were collected belonging to 594 species, which is about 60% of the Hungarian fauna. 216 species occurred in each year. Noctuidae and Geometridae were most rich in species and most abundant. Arctiidae, Lasiocampidae, Notodontidae and Sphingidae were also represented in a considerable proportion. The analysis of the flight activity curves shows two summer peaks and also a smaller spring and an autumn peak. The faunal type composition of the species and their abundance, respectively, was the following: Transpalearctic (48.15%, 55.68%), Boreo Continental (18.86, 8.16%), South Continental (2.02%, 0.67%), West Palaearctic (28.96%, 35.14%), Xeromontane (1.01%, 0.05%) and Extrapalaearctic (1.01%, 0.31%). The eco-faunal components: euryoecious (11.62%, 20.03%), silvicolous (17.34%, 20.12%), nemoral (8.08%, 9.86%), quercetal (12.46%, 12.66%), helophilous (5.56%, 1.85%), boreo-montane (1.18%, 1.12%), altoherbosa (5.22%, 3.49%), meso-hygrophilous (6.73%, 6.26%), steppic (10.44%, 7.17%), lichenophagous (2.02%, 14.13%), other (19.36%, 3.32%)
Kondo Behavior of U in CaB
Replacing U for Ca in semiconducting CaB at the few at.% level induces
metallic behaviour and Kondo-type phenomena at low temperatures, a rather
unusual feature for U impurities in metallic hosts. For
CaUB, the resistance minimum occurs at = 17 K. The
subsequent characteristic logarithmic increase of the resistivity with
decreasing temperature merges into the expected dependence below 0.8 K.
Data of the low-temperature specific heat and the magnetization are analyzed by
employing a simple resonance-level model. Analogous measurements on LaB
with a small amount of U revealed no traces of Kondo behavior, above 0.4 K.Comment: 4 pages, 4 figures, submitted for publication to Europhysics Letter
PtOx-SnOx-TiO2 catalyst system for methanol photocatalytic reforming: Influence of cocatalysts on the hydrogen production
Effects of modification of PtOx-TiO2 photocatalysts by tin were elucidated by exploring relationships between the structural properties of variously prepared tin-loaded catalysts and their catalytic activity in methanol photocatalytic reforming. Tin free and amorphous tin-oxide decorated TiO2 samples were prepared by sol-gel method from titanium-isopropoxide. In other approach, Sn was loaded onto the sol-gel prepared TiO2 by impregnation followed by calcination. Pt was introduced by impregnation followed by either reduction in H2 at 400 °C or calcination at 300 °C. TEM, XRD and Raman spectroscopic measurements proved that TiO2 existed in the form of aggregates of polycrystalline anatase with primary particle size of 15â20 nm in all samples. Photocatalytic hydrogen production was influenced by the combined effect of many parameters. Both the presence of Sn and the way of Pt co-catalyst formation played important role in the activity of these photocatalysts. The Sn introduction by both sol-gel method and impregnation clearly enhanced the photocatalytic activity. 1H MAS NMR measurements revealed that the Sn introduction reduced the amount of the terminal Ti-OH groups of relatively basic character considered to be unfavorable for the photocatalytic reaction. Presence of SnOx decreased the signal of the undesirable vacancies observed by ESR. Furthermore surface SnOx enhanced the dispersion of Pt. Formation of the Pt co-catalyst by calcination was more favorable than by H2 treatment. In case of the calcined samples in situ reduction of the Pt nanoparticles at the beginning of the photocatalytic reaction was found to be favorable for the hydrogen production. The relatively modest photocatalytical activity obtained after high temperature H2 treatment could be related to at least two processes in this system: (i) creation of unfavorable oxygen vacancies and (ii) segregation of SnOx to the surface of the Pt cocatalyst as the result of the air exposure of the alloy type Pt-Sn nanoparticles formed during the H2 treatment, resulting in a decreased number of active sites for reduction of H+
FHR-1 binds to C-reactive protein and enhances rather than inhibits complement activation
Factor H (FH)-related protein 1 (FHR-1) is one
of the five human factor H-related proteins,
which share sequence and structural homology
with the alternative pathway complement
inhibitor FH. Genetic studies on
disease associations and functional analyses indicate that
FHR-1 enhances complement activation by co
mpetitive inhibition of FH binding to some
surfaces and immune proteins. We have recen
tly shown that FHR-1 binds to pentraxin 3.
Here, our aim was to investigate whether FH
R-1 binds to another
pentraxin, C-reactive
protein (CRP), analyze the functional relevance
of this interaction and study the role of FHR-
1 in complement activation and regulation. FHR-
1 did not bind to native,
pentameric CRP but
it bound strongly to monomeric CRP via its C-term
inal domains. FHR-1 at high concentration
competed with FH for CRP binding, indicating
possible complement de
-regulation also on
this ligand. FHR-1 did not inhibi
t regulation of solid phase C3 convertase by FH and did not
inhibit terminal complement complex forma
tion induced by zymosan. On the contrary, by
binding C3b, FHR-1 allowed C3 convertase form
ation and thereby enhanced complement
activation. FHR-1/CRP interacti
ons increased complement activ
ation via the classical and
alternative pathways on surfaces such as th
e extracellular matrix and necrotic cells.
Altogether, these results identify CRP as a lig
and for FHR-1 and suggest
that FHR-1 enhances
rather than inhibits complement activation, wh
ich may explain the protective effect of FHR-1
deficiency in age-related macular degeneration
PSMB7 is associated with anthracycline resistance and is a prognostic biomarker in breast cancer
BACKGROUND: To date individual markers have failed to correctly predict resistance against anticancer agents in breast cancer. We used gene expression patterns attributable to chemotherapy-resistant cells to detect potential new biomarkers related to anthracycline resistance. One of the genes, PSMB7, was selected for further functional studies and clinical validation. METHODS: We contrasted the expression profiles of four pairs of different human tumour cell lines and of their counterparts resistant to doxorubicin. Observed overexpression of PSMB7 in resistant cell lines was validated by immunohistochemistry. To examine its function in chemoresistance, we silenced the gene by RNA interference (RNAi) in doxorubicin-resistant MCF-7 breast cancer cells, then cell vitality was measured after doxorubicin treatment. Microarray gene expression from GEO raw microarray samples with available progression-free survival data was downloaded, and expression of PSMB7 was used for grouping samples. RESULTS: After doxorubicin treatment, 79.8+/-13.3% of resistant cells survived. Silencing of PSMB7 in resistant cells decreased survival to 31.8+/-6.4% (P>0.001). A similar effect was observed after paclitaxel treatment. In 1592 microarray samples, the patients with high PSMB7 expression had a significantly shorter survival than the patients with low expression (P<0.001). CONCLUSION: Our findings suggest that high PSMB7 expression is an unfavourable prognostic marker in breast cancer
Oscillations in Quantum Entanglement During Rescattering
We study the time evolution of quantum entanglement between an electron and
its parent ion during the rescattering due to a strong few-cycle laser pulse.
Based on a simple one-dimensional model, we compute the Neumann entropy during
the process for several values of the carrier-envelope phase. The local maxima
of the oscillations in the Neumann entropy coincide with the zero crossings of
the electric field of the laser pulse. We employ the Wigner function to
qualitatively explain the quantum dynamics of rescattering in the phase space.Comment: 2 page
Weak convergence of finite element approximations of linear stochastic evolution equations with additive noise II. Fully discrete schemes
We present an abstract framework for analyzing the weak error of fully
discrete approximation schemes for linear evolution equations driven by
additive Gaussian noise. First, an abstract representation formula is derived
for sufficiently smooth test functions. The formula is then applied to the wave
equation, where the spatial approximation is done via the standard continuous
finite element method and the time discretization via an I-stable rational
approximation to the exponential function. It is found that the rate of weak
convergence is twice that of strong convergence. Furthermore, in contrast to
the parabolic case, higher order schemes in time, such as the Crank-Nicolson
scheme, are worthwhile to use if the solution is not very regular. Finally we
apply the theory to parabolic equations and detail a weak error estimate for
the linearized Cahn-Hilliard-Cook equation as well as comment on the stochastic
heat equation
Energy gap in superconducting fullerides: optical and tunneling studies
Tunneling and optical transmission studies have been performed on
superconducting samples of Rb3C60. At temperatures much below the
superconducting transition temperature Tc the energy gap is 2 Delta=5.2 +-
0.2meV, corresponding to 2 Delta/kB Tc = 4.2. The low temperature density of
states, and the temperature dependence of the optical conductivity resembles
the BCS behavior, although there is an enhanced ``normal state" contribution.
The results indicate that this fulleride material is an s-wave superconductor,
but the superconductivity cannot be described in the weak coupling limit.Comment: RevTex file with four .EPS figures. Prints to four pages. Also
available at http://buckminster.physics.sunysb.edu/papers/pubrece.htm
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