Generation of broadband femtosecond visible pulses in dispersion-micromanaged holey fibers

Submillimeter-scale dispersion micromanagement (DMM) is used to generate coherent and stable femtosecond visible pulses in holey fibers as short as 10 mm. The longitudinal variation of the phase-matching conditions for Cerenkov radiation and four-wave mixing explains the results well. We have converted up to 20% of the total input energy to a low-noise solitary wave with a bandwidth up to 50 nm in the range 385-625 nm by using holey fibers with various DMM designs.     

Delayed luminescence analysis (DLA) of purine and pyrimidine ribose and deoxyribose nucleotide triphosphates in picomole quantities

A discovery is reported of a new system that enables one to quantitate the amounts of separated nucleotide triphosphates in picomole quantities. This system of delayed luminescence analysis (DLA) is sensitive to both purine and pyrimidine ribose and deoxyribose nucleotide triphosphates. A crude luciferin-luciferase (substrate-enzyme) preparation from firefly lanterns, in the presence of nucleotide triphosphate, is utilized to generate light that is detected by a liquid scintillation counter with the coincidence of the photomultiplier tubes turned off. Light is produced in a delayed fashion, the maximum emission being dependent on the type of nucleotide. Purine nucleotides (GTP, ITP, dATP, dGTP) give maximal light emission at approximately 2 mins; with the pyrimidine nucleotides the time required for maximal light emission was 5 min for UTP, dUTP, and TTP, 10 min for CTP, and 12 min for dCTP. A linear relationship on a log-log plot of light emission vs. concentration of nucleotide is demonstrated with ITP, dATP, UTP, and CTP.     

Optical properties of quasi-zero-dimensional magneto-excitons

We discuss the evolution of optical properties of semiconductor quantum wells, as the quasi-two-dimensional electronic states are further confined into quasi-zero dimensions by a perpendicular magnetic field. We show that confinement in all three directions strongly modifies both linear and nonlinear optical response. In particular, quasi-zero-dimensionality makes an ensemble of magneto-excitons a unique many-body system, distinct from higher-dimensional excitons and the one-component Coulomb system in the fractional quantum Hall regime or Wigner crystal.     

Studies of luminol-dependent whole-blood chemiluminescence induced by platelet-activating factor (PAF)

A whole-blood luminol-dependent chemiluminescence (CL) assay stimulated by platelet-activating factor (PAF) is reported. Factors investigated using this assay were dilution of blood, dose responsiveness of PAF, and inactivation of PAF. The final conditions chosen for the assay were a 1:10 dilution of whole blood and 2 × 10^?4M luminol. Nordihydroguaiaretic acid (NDGA) and indomethacin (INDO), which inhibit lipoxygenase and cyclooxygenase, decreased luminol-dependent whole-blood chemiluminescence by 59 and 17%, respectively. Superoxide dismutase and catalase were relatively ineffective inhibitors of CL (28 and 22%, respectively) while sodium azide was most inhibitory (84%). Although these studies were not entirely conclusive, lipoxygenase and myeloperoxidase appear to be important in CL elicited by PAF in this whole-blood CL assay. This system may serve as a useful screening system for measuring the effect of PAF in the blood of different individuals without extensive separation of cell types. It has the distinct advantage of being closer to in situ Conditions.     

Control of dispersion in capillary electrochromatography coupled to UV and mass spectrometric detection

Capillary electrochromatography (CEC), along with other miniaturised chromatography techniques, such as capillary LC, offers the most benefit when efficiently coupled to mass spectrometric (MS) detectors. In conventional one-piece CEC columns, dispersion in the open connecting tube between the packed column and MS source reduces chromatographic performance to unacceptable levels. This paper examines the effect on dispersion of various column-tube arrangements and offers suggestions as to the most practical way of connecting CEC-UV-MS. Comparisons of theoretical and measured values for these different arrangements are shown.     

Acoustic analysis and mood classification of pain-relieving music

Listening to preferred music (that which is chosen by the participant) has been shown to be effective in mitigating the effects of pain when compared to silence and a variety of distraction techniques. The wide range of genre, tempo, and structure in music chosen by participants in studies utilizing experimentally induced pain has led to the assertion that structure does not play a significant role, rather listening to preferred music renders the music "functionally equivalent" as regards its effect upon pain perception. This study addresses this assumption and performs detailed analysis of a selection of music chosen from three pain studies. Music analysis showed significant correlation between timbral and tonal aspects of music and measurements of pain tolerance and perceived pain intensity. Mood classification was performed using a hierarchical Gaussian Mixture Model, which indicated the majority of the chosen music expressed contentment. The results suggest that in addition to personal preference, associations with music and the listening context, emotion expressed by music, as defined by its acoustical content, is important to enhancing emotional engagement with music and therefore enhances the level of pain reduction and tolerance.     

Ultrastructure and composition of cell wall appositions in the roots of Asplenium (Polypodiales)

Cell wall appositions (CWAs), formed by the deposition of extra wall material at the contact site with microbial organisms, are an integral part of the response of plants to microbial challenge. Detailed histological studies of CWAs in fern roots do not exist. Using light and electron microscopy we examined the (ultra)structure of CWAs in the outer layers of roots of Asplenium species. All cell walls studded with CWAs were impregnated with yellow-brown pigments. CWAs had different shapes, ranging from warts to elongated branched structures, as observed with scanning and transmission electron microscopy. Ultrastructural study further showed that infecting fungi grow intramurally and that they are immobilized by CWAs when attempting to penetrate intracellularly. Immunolabelling experiments using monoclonal antibodies indicated pectic homogalacturonan, xyloglucan, mannan and cellulose in the CWAs, but tests for lignins and callose were negative. We conclude that these appositions are defense-related structures made of a non-lignified polysaccharide matrix on which phenolic compounds are deposited in order to create a barrier protecting the root against infections.