Search results for " PUM"
showing 10 items of 412 documents
Computational investigation and experimental considerations for the classical implementation of a full adder on SO2 by optical pump-probe schemes
2008
International audience; Following the scheme recently proposed by Remacle and Levine Phys. Rev. A 73, 033820 2006 , we investigate the concrete implementation of a classical full adder on two electronic states X˜ 1A1 and C ˜ 1B2 of the SO2 molecule by optical pump-probe laser pulses using intuitive and counterintuitive stimulated Raman adiabatic passage excitation schemes. The resources needed for providing the inputs and reading out are discussed, as well as the conditions for achieving robustness in both the intuitive and counterintuitive pump-dump sequences. The fidelity of the scheme is analyzed with respect to experimental noise and two kinds of perturbations: The coupling to the neigh…
Differential salinity-induced variations in the activity of H+-pumps and Na+/H+ antiporters that are involved in cytoplasm ion homeostasis as a funct…
2011
The characterisation of cellular responses to salinity in staple crops is necessary for the reliable identification of physiological markers of salinity tolerance. Under saline conditions, variations in proton gradients that are generated by membrane-bound H⁺ pumps are crucial for maintaining cytoplasm homeostasis. We examined short (15 h) and longer term effects (4 days) of NaCl stress on the H⁺ pumping activities that are associated with the plasma membrane (P-ATPase) and the tonoplast (V-ATPase and V-PPase) in rice (Oryza sativa L.) callus lines that displayed different levels of NaCl tolerance and were established from two japonica rice cultivars. The applied stress conditions were base…
A continuous infusion of a minor histocompatibility antigen-immunodominant peptide induces a delay of male skin graft rejection.
2009
Abstract We previously reported that an inhibition of antigen-specific Interferon-γ release and cytotoxicity occurs after a continuous infusion of an HY immunodominant peptide although this treatment is not able to cause a significant delay of male skin grafts rejection. In vivo administration of high doses of an HY peptide, through mini-osmotic pumps, in naive female mice was used to study the effects on the male skin grafts rejection. A continuous infusion of 1 mg of an HY peptide induces a significant delay of male skin graft rejection. In vitro HY-specific Interferon-γ release was inhibited adding peptide-specific suppressor cells: the ability to inhibit Interferon-γ release was evident…
INNOVATIVE PHOTOVOLTAIC-THERMAL HEAT PUMP SOLUTIONS FOR DOMESTIC HOT WATER PRODUCTION
2022
With the rapid growth of energy consumption in the building sector and the consequent necessity to develop energy efficiency strategies, the application of heat pump systems seems to be a competitive solution to improve energy efficiency. In particular, air-source heat pump (ASHP) systems assisted by solar energy have drawn great attention, owing to their great feasibility in buildings for space heating/cooling and hot ater production purposes. The complementation system between solar and air energy can solve the poor performance of the air source heat pump under low-temperature conditions and can also make up for the shortcoming of the solar collector as an unstable energy source. Both sol…
Heterotrophic microorganisms in deteriorated medieval wall paintings in southern Italian churches
2008
The Campania region in southern Italy is noted for its large number of churches that harbour invaluable frescoes, dated from the beginnings of the 4th up to the 13th century. The wall paintings represent an integral part of the monuments, and their deterioration constitutes a potentially significant loss for the world's cultural heritage. Heterotrophic microorganisms such as bacteria and mould can grow on the surface of paintings that contain a wide range of organic and inorganic constituents, and provide different ecological. niches that are exploited by a large variety of microbial. species. We isolated and identified the heterotrophic microorganisms found in the biodegraded medieval wall…
Ultrafast Optical Demagnetization manipulates Nanoscale Spin Structure in Domain Walls
2012
During ultrafast demagnetization of a magnetically ordered solid, angular momentum has to be transferred between the spins, electrons, and phonons in the system on femto- and picosecond timescales. Although the intrinsic spin-transfer mechanisms are intensely debated, additional extrinsic mechanisms arising due to nanoscale heterogeneity have only recently entered the discussion. Here we use femtosecond X-ray pulses from a free-electron laser to study thin film samples with magnetic domain patterns. We observe an infrared-pump-induced change of the spin structure within the domain walls on the sub-picosecond timescale. This domain-topography-dependent contribution connects the intrinsic dem…
STACKING-FAULTS IN VERY FINE PALLADIUM PARTICLES SUPPORTED ON PUMICE
1990
By means of an X-ray diffraction study, carried out with best-fitting procedures, of the asymmetry and peak maximum shifts of some reflections, stacking-faults in the FCC lattice of very fine palladium particles supported on pumice were detected using the Warren-Wagner-Cohen theoretical approach.
A distributed model for continuous-wave erbium-doped fiber laser
2011
Abstract A distributed model of a continuous-wave erbium-doped fiber laser is discussed. The model is based on two contra-propagated traveling laser waves, and includes inhomogeneous pumping, excited state absorption at the pump and the laser wavelengths, amplified spontaneous emission and radial distribution of populations of erbium levels. It is shown that excited state absorption is a main limiting factor to the laser's efficiency. Moreover, consideration of radial distributions of erbium levels' populations in the model reduces laser efficiency and decreases optimal reflection of the laser output coupler. The modeling results are in excellent agreement with the experimental study on the…
High-efficiency Q-switched erbium fiber laser using a Bragg grating-based modulator
2002
Abstract In this work we analyze the behavior of an erbium-doped fiber laser which is based on a simple scheme. Excitation of the active medium is performed in the 980 nm pump band with a CW semiconductor laser source. Two fiber Bragg gratings acting as mirrors of the Fabry–Perot laser cavity were used. One of these gratings was mounted over a piezoelectric (PZT) element. By applying voltage pulses to the piezoelectric, the laser cavity was temporally modulated and Q-switched laser pulses up to 530 mW peak powers at 3 kHz were obtained. Typical laser emission of 2–3 μs temporal widths and 0.1 nm of optical bandwidth have been achieved when the system was operated at 18.5 kHz repetition rate…
Dual-kind Q-switching of erbium fiber laser
2014
Two different regimes of Q-switching in the same implementation of an actively Q-switched erbium-doped fiber laser are demonstrated. Depending on the active fiber length and repetition rate of an intracavity Q-cell (acousto-optic modulator), the laser operates either in the regime of common, rather long and low-power, pulses composed of several sub-pulses or in the one of very short and powerful stimulated Brillouin scattering-induced pulses. The basic physical reason of the laser system to oscillate in one of these two regimes is the existence or absence of CW narrow-line “bad-cavity” lasing in the intervals when the Q-cell is blocked.