Neutron-detected tomography of impurity-seeded superfluid helium

We describe a neutron radiography technique that can be used to map the distribution of 3He impurities in liquid 4He, providing direct and quantitative access to underlying transport processes. Images reflecting finite normal- and superfluid-component 4He velocity fields are presented.     

Beam-focus shaping by use of programmable phase-only filters: application to an ultralong focal line

We have developed a high-resolution programmable adaptive-optic device based on an optically addressed liquid-crystal electro-optic valve controlled by an achromatic three-wave lateral shearing interferometer. We apply this phase-only filter and loop to shape the far-field pattern of laser beams. As a first application, we theoretically compute and experimentally verify the focus along a line longer than tens of Rayleigh ranges.     

Heating of thin foils with a relativistic-intensity short-pulse laser

K-shell x-ray spectroscopy of sub-100 nm Al foils irradiated by high contrast, spatially uniform, 150 fs, Ilambda (2)=2 x 10(18) W microm(2)/cm(2), laser pulses is obtained with 500 fs time resolution. Two distinct phases occur: At /=500 fs the resonance transitions dominate. Initial satellites arise from a large area, high density, low temperature (approximately 100 eV) plasma created by fast electrons. Thus, contrary to predictions, a short, high intensity laser incident on a thin foil does not create a uniform, hot dense plasma.     

Ultrafast back electron transfer processes in the photoexcited methylviologen-iodide charge transfer complexes

The ultrafast back electron transfer in the excited charge transfer complexes of the methylviologen with iodide ions has been investigated using femtosecond transient absorption spectroscopy. Methylviologen and iodide form two types of charge transfer complexes each characterized by a charge transfer band in the same spectral region. At low I^- concentrations mainly a 1:1 complex MV²⁺(I^-) is present while at high I^- concentrations both 1:1 and 1:2 complexes MV²⁺(I^-)₂ can be observed. Ultrashort laser pulses at 400 nm are used to excite both complexes in their charge transfer band. The observed transient absorption can be represented by a biexponential function with 1 ps and 20 ps time constants and attributed to the decay of the MV^+./I^. and MV^+./I₂ ^.- radical pair respectively. The excitation of the 1:1 complex leads to the formation of the MV^+./I^. radical pair while the excitation of the 1:2 complex leads to the formation of the MV^+./I^. and MV^+./I₂ ^.- radical pairs.     

Limit of spin squeezing in finite-temperature Bose-Einstein condensates

We show that, at finite temperature, the maximum spin squeezing achievable using interactions in Bose-Einstein condensates has a finite limit when the atom number N→∞ at fixed density and interaction strength. We calculate the limit of the squeezing parameter for a spatially homogeneous system and show that it is bounded from above by the initial noncondensed fraction.     

Dynamic model for a defective production system with Poka-Yoke

This paper proposes a dynamic model for a defective production system with Poka-Yoke. Poka-Yoke is a Japanese phrase which means mistake-proofing. The technique of Poka-Yoke has been diversely applied in modern production systems. In this study, we evaluate the total cost of a defective production system with Poka-Yoke. We also use a practical case in automotive industry to verify the proposed model. The case study reveals that Poka-Yoke is a cost-effective mechanism that generates satisfactory return of a defective production system, the effect of which depends on the investment cost of Poka-Yoke.     

Time-resolved observation of the Eigen cation in liquid water

Experimental observation and time relaxation measurement of the hydrated proton Eigen form [H(3)O(+)(H(2)O)(3)] are presented here. Vibrational time-resolved spectroscopy is used with an original method of investigating the proton excess in water. The anharmonicity of the time-resolved spectra is characteristic of the Eigen-type proton geometry. Proton relaxation occurs in less than 200 fs. A calculation of the potential energy confirms the experimental result and the Eigen cation lifetime is in good agreement with previous molecular dynamics simulations.     

Surface plasmon interference excited by tightly focused laser beams

We show that interfering surface plasmon polaritons can be excited with a focused laser beam at normal incidence to a plane metal film. No protrusions or holes are needed in this excitation scheme. Depending on the axial position of the focus, the intensity distribution on the metal surface is either dominated by interferences between counterpropagating plasmons or by a two-lobe pattern characteristic of localized surface plasmon excitation. Our experiments can be accurately explained by use of the angular spectrum representation and provide a simple means for locally exciting standing surface plasmon polaritons.     

Nuclear charge radius of 8He

The root-mean-square (rms) nuclear charge radius of 8He, the most neutron-rich of all particle-stable nuclei, has been determined for the first time to be 1.93(3) fm. In addition, the rms charge radius of 6He was measured to be 2.068(11) fm, in excellent agreement with a previous result. The significant reduction in charge radius from 6He to 8He is an indication of the change in the correlations of the excess neutrons and is consistent with the 8He neutron halo structure. The experiment was based on laser spectroscopy of individual helium atoms cooled and confined in a magneto-optical trap. Charge radii were extracted from the measured isotope shifts with the help of precision atomic theory calculations.     

A hierarchical decomposition approach to retail shelf space management and assortment decisions

Shelf management is a crucial task in retailing. Because of the large number of products found in most retail stores (sometimes more than 60?000), current shelf space management models can only solve sub-problems of the overall store optimization problem, since the size of the complete optimization problem would be prohibitively large. Consequently, an optimal allocation of store shelf space to products has not yet been achieved. We show that a hierarchical decomposition technique, consisting of two interwoven models, is suitable to overcome this limitation and, thus, is capable of finding accurate solutions to very large and complex shelf space management problems. We further conclude that other important variables (such as product-price) can be included into the methodology and their optimal values can be determined using the same solution technique. Our methodology is illustrated on a real-life application where we predict a 22.33% increase in store profits if our model's solution is implemented.