6,912 research outputs found
Stability of the self-phase-locked pump-enhanced singly resonant parametric oscillator
Steady-state and dynamics of the self-phase-locked (3\omega ==> 2\omega,
\omega) subharmonic optical parametric oscillator are analyzed in the
pump-and-signal resonant configuration, using an approximate analytical model
and a full propagation model. The upper branch solutions are found always
stable, regardless of the degree of pump enhancement. The domain of existence
of stationary states is found to critically depend on the phase-mismatch of the
competing second-harmonic process.Comment: LateX2e/RevteX4, 4 pages, 5 figures. Submitted to Phys. Rev. A
(accepted on Jan. 17, 2003
Functional consequences of sphingomyelinase-induced changes in erythrocyte membrane structure.
Inflammation enhances the secretion of sphingomyelinases (SMases). SMases catalyze the hydrolysis of sphingomyelin into phosphocholine and ceramide. In erythrocytes, ceramide formation leads to exposure of the removal signal phosphatidylserine (PS), creating a potential link between SMase activity and anemia of inflammation. Therefore, we studied the effects of SMase on various pathophysiologically relevant parameters of erythrocyte homeostasis. Time-lapse confocal microscopy revealed a SMase-induced transition from the discoid to a spherical shape, followed by PS exposure, and finally loss of cytoplasmic content. Also, SMase treatment resulted in ceramide-associated alterations in membrane-cytoskeleton interactions and membrane organization, including microdomain formation. Furthermore, we observed increases in membrane fragility, vesiculation and invagination, and large protein clusters. These changes were associated with enhanced erythrocyte retention in a spleen-mimicking model. Erythrocyte storage under blood bank conditions and during physiological aging increased the sensitivity to SMase. A low SMase activity already induced morphological and structural changes, demonstrating the potential of SMase to disturb erythrocyte homeostasis. Our analyses provide a comprehensive picture in which ceramide-induced changes in membrane microdomain organization disrupt the membrane-cytoskeleton interaction and membrane integrity, leading to vesiculation, reduced deformability, and finally loss of erythrocyte content. Understanding these processes is highly relevant for understanding anemia during chronic inflammation, especially in critically ill patients receiving blood transfusions
Heat capacity and pairing transition in nuclei
A simple model based on the canonical-ensemble theory is outlined for hot
nuclei. The properties of the model are discussed with respect to the Fermi gas
model and the breaking of Cooper pairs. The model describes well the
experimental level density of deformed nuclei in various mass regions. The
origin of the so-called S-shape of the heat capacity curve Cv(T) is discussed.Comment: 6 pages + 8 figure
Exact Treatment of the Pauli Exclusion Operator in Nuclear Matter Calculation
Exact expressions of the Pauli exclusion operator Q in the nuclear matter
calculation are presented in detail. Exact formulae are also given for the
calculations of the single-particle-potential energy and the binding energy per
nucleon with the exact Q operator. Numerical calculations of the G matrix in
the lowest-order Brueckner theory are carried out to check the reliability of
the standard angle-average approximation for the
Q operator by employing the Bonn B and C NN potentials. It is observed that
the exact treatment of the operator Q brings about non-negligible and
attractive contributions to the binding energy.Comment: 16 pages, 3 figure
Kondo-lattice model: Application to the temperature-dependent electronic structure of EuO(100) films
We present calculations for the temperature-dependent electronic structure
and magnetic properties of thin ferromagnetic EuO films. The treatment is based
on a combination of a multiband-Kondo lattice model with first-principles
TB-LMTO band structure calculations. The method avoids the problem of
double-counting of relevant interactions and takes into account the correct
symmetry of the atomic orbitals. We discuss the temperature-dependent
electronic structures of EuO(100) films in terms of quasiparticle densities of
states and quasiparticle band structures. The Curie temperature T_C of the EuO
films turns out to be strongly thickness-dependent, starting from a very low
value = 15K for the monolayer and reaching the bulk value at about 25 layers
E5501: phase II study of topotecan sequenced with etoposide/cisplatin, and irinotecan/cisplatin sequenced with etoposide for extensive-stage small-cell lung cancer.
PURPOSE: Sequence-dependent improved efficacy of topoisomerase I followed by topoisomerase 2 inhibitors was assessed in a randomized phase II study in extensive-stage small-cell lung cancer (SCLC).
METHODS: Patients with previously untreated extensive-stage SCLC with measurable disease, ECOG performance status of 0-3 and stable brain metastases were eligible. Arm A consisted of topotecan (0.75 mg/m(2)) on days 1, 2 and 3, etoposide (70 mg/m(2)) and cisplatin (20 mg/m(2)) (PET) on days 8, 9 and 10 in a 3-week cycle. Arm B consisted of irinotecan (50 mg/m(2)) and cisplatin (20 mg/m(2)) on days 1 and 8 followed by etoposide (85 mg/m(2) PO bid) on days 3 and 10 (PIE) in a 3-week cycle.
RESULTS: We enrolled 140 patients and randomized 66 eligible patients to each arm. Only 54.5 % of all patients completed the planned maximum 6 cycles. There were grade ≥3 treatment-related adverse events in approximately 70 % of the patients on both arms including 6 treatment-related grade 5 events. The overall response rates (CR + PR) were 69.7 % (90 % CI 59.1-78.9, 95 % CI 57.1-80.4 %) for arm A and 57.6 % (90 % CI 46.7-67.9, 95 % CI 44.8-69.7 %) for arm B. The median progression-free survival and overall survival were 6.4 months (95 % CI 5.4-7.5 months) and 11.9 months (95 % CI 9.6-13.7 months) for arm A and 6.0 months (95 % CI 5.4-7.0 months) and 11.0 months (95 % CI 8.6-13.1 months) for arm B.
CONCLUSION: Sequential administration of topoisomerase inhibitors did not improve on the historical efficacy of standard platinum-doublet chemotherapy for extensive-stage SCLC
Maximum likelihood estimation of photon number distribution from homodyne statistics
We present a method for reconstructing the photon number distribution from
the homodyne statistics based on maximization of the likelihood function
derived from the exact statistical description of a homodyne experiment. This
method incorporates in a natural way the physical constraints on the
reconstructed quantities, and the compensation for the nonunit detection
efficiency.Comment: 3 pages REVTeX. Final version, to appear in Phys. Rev. A as a Brief
Repor
Novel High-Frequency Air Transducers
Ultrasonic transducers operating in air in the frequency range of 1–10MHz have major applications in robotics and nondestructive evaluation. For robotics applications, high-frequency air transducers make possible range measurements with a resolution in the 30–100 μm range. For nondestructive evaluation, it is possible to make transmission C-scan systems operating in air for the inspection of composites, green ceramics, and even metals at elevated temperatures. In this work, we report on the use of ligneous materials as a matching layer for PZT-based transducers
Observation of twin beam correlations and quadrature entanglement by frequency doubling in a two-port resonator
We demonstrate production of quantum correlated and entangled beams by second
harmonic generation in a nonlinear resonator with two output ports. The output
beams at wavelength 428.5 nm exhibit 0.9 dB of nonclassical intensity
correlations and 0.3 dB of entanglement.Comment: 5 pages, 7 figure
Level densities and -strength functions in Sm
The level densities and -strength functions of the weakly deformed
Sm and Sm nuclei have been extracted. The temperature versus
excitation energy curve, derived within the framework of the micro canonical
ensemble, shows structures, which we associate with the break up of Cooper
pairs. The nuclear heat capacity is deduced within the framework of both the
micro canonical and the canonical ensemble. We observe negative heat capacity
in the micro canonical ensemble whereas the canonical heat capacity exhibits an
S-shape as function of temperature, both signals of a phase transition. The
structures in the -strength functions are discussed in terms of the
pygmy resonance and the scissors mode built on exited states. The samarium
results are compared with data for the well deformed Dy,
Er and Yb isotopes and with data from
(n,)-experiments and giant dipole resonance studies.Comment: 12 figure
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