Near-field scanning optical microscopic transient lens for carrier dynamics study in InGaN/GaN

Time-resolved microscopic transient lens (TR-M-TL) and near-field scanning optical microscopic transient lens (NSOM-TL) were performed to reveal temporal and spatial behavior of carrier dynamics in InGaN/GaN quantum wells. The carrier and thermal dynamics were observed through the time profile of the TR-M-TL signal. Also, NSOM-photoluminescence and NSOM-TL images were observed at the same time. By comparing these two images, both radiative and nonradiative recombination centers in InGaN active layer were unambiguously discriminated with submicrometer scale. Such nonradiative carrier dynamics has been difficult to observe by conventional techniques in spite of its importance

Tol2: a versatile gene transfer vector in vertebrates

The medaka fish Tol2 element is an autonomous transposon that encodes a fully functional transposase. The transposase protein can catalyze transposition of a transposon construct that has 200 and 150 base pairs of DNA from the left and right ends of the Tol2 sequence, respectively. These sequences contain essential terminal inverted repeats and subterminal sequences. DNA inserts of fairly large sizes (as large as 11 kilobases) can be cloned between these sequences without reducing transpositional activity. The Tol2 transposon system has been shown to be active in all vertebrate cells tested thus far, including zebrafish, Xenopus, chicken, mouse, and human. In this review I describe and discuss how the Tol2 transposon is being applied to transgenic studies in these vertebrates, and possible future applications

Transposon-mediated BAC transgenesis in zebrafish and mice

<p>Abstract</p> <p>Background</p> <p>Bacterial artificial chromosomes (BACs) are among the most widely used tools for studies of gene regulation and function in model vertebrates, yet methods for predictable delivery of BAC transgenes to the genome are currently limited. This is because BAC transgenes are usually microinjected as naked DNA into fertilized eggs and are known to integrate as multi-copy concatamers in the genome. Although conventional methods for BAC transgenesis have been very fruitful, complementary methods for generating single copy BAC integrations would be desirable for many applications.</p> <p>Results</p> <p>We took advantage of the precise cut-and-paste behavior of a natural transposon, <it>Tol2</it>, to develop a new method for BAC transgenesis. In this new method, the minimal sequences of the <it>Tol2 </it>transposon were used to deliver precisely single copies of a ~70 kb BAC transgene to the zebrafish and mouse genomes. We mapped the BAC insertion sites in the genome by standard PCR methods and confirmed transposase-mediated integrations.</p> <p>Conclusion</p> <p>The <it>Tol2 </it>transposon has a surprisingly large cargo capacity that can be harnessed for BAC transgenesis. The precise delivery of single-copy BAC transgenes by <it>Tol2 </it>represents a useful complement to conventional BAC transgenesis, and could aid greatly in the production of transgenic fish and mice for genomics projects, especially those in which single-copy integrations are desired.</p

Surface plasmon enhanced spontaneous emission rate of InGaN/GaN quantum wells probed by time-resolved photoluminescence spectroscopy

We observed a 32-fold increase in the spontaneous emission rate of InGaN/GaN quantum well (QW) at 440 nm by employing surface plasmons (SPs) probed by time-resolved photoluminescence spectroscopy. We explore this remarkable enhancement of the emission rates and intensities resulting from the efficient energy transfer from electron-hole pair recombination in the QW to electron vibrations of SPs at the metal-coated surface of the semiconductor heterostructure. This QW-SP coupling is expected to lead to a new class of super bright and high-speed light-emitting diodes (LEDs) that offer realistic alternatives to conventional fluorescent tubes

<CLINICAL>Clinical results of vital tooth bleaching : 1. In-office bleaching

In recent years, demand for esthetic dentistry has grown, particularly with respect to treatment of discolored anterior teeth. Tooth discoloration and pigmentation can be treated by polishing or bleaching the tooth, or by laminate veneering. Bleaching is widely used, since it allows esthetic restoration without removal of the tooth surface. However, its tooth-bleaching efficacy is often assessed in a subjective manner. This report describes the use of in-office bleaching of tetracycline-induced tooth discoloration and yellowed teeth using Hi-Lite^ and Power Gel^, respectively, and objective assessment of efficacy. In both cases, excellent improvement in tooth color was noted, with a color difference (AE) from baseline of 5.8-6.5. These results support that in-office bleaching using Hi-Lite^ or Power Gel^ is a safe and efficacious method for the treatment of tooth discoloration

Afferent Neurons of the Zebrafish Lateral Line Are Strict Selectors of Hair-Cell Orientation

Hair cells in the inner ear display a characteristic polarization of their apical stereocilia across the plane of the sensory epithelium. This planar orientation allows coherent transduction of mechanical stimuli because the axis of morphological polarity of the stereocilia corresponds to the direction of excitability of the hair cells. Neuromasts of the lateral line in fishes and amphibians form two intermingled populations of hair cells oriented at 180° relative to each other, however, creating a stimulus-polarity ambiguity. Therefore, it is unknown how these animals resolve the vectorial component of a mechanical stimulus. Using genetic mosaics and live imaging in transgenic zebrafish to visualize hair cells and neurons at single-cell resolution, we show that lateral-line afferents can recognize the planar polarization of hair cells. Each neuron forms synapses with hair cells of identical orientation to divide the neuromast into functional planar-polarity compartments. We also show that afferent neurons are strict selectors of polarity that can re-establish synapses with identically oriented targets during hair-cell regeneration. Our results provide the anatomical bases for the physiological models of signal-polarity resolution by the lateral line

<CLINICAL>Atraumatic restoration in amelogenesis imperfecta using flowable composite resin

Amelogenesis imperfecta causes defects in the tooth enamel. These defects can appear as small pits or dents in the tooth or can be so widespread as to make the entire tooth small in size and/or mis-shaped. This may result in tooth sensitivity, an unsightly appearance and/or increased susceptibility to dental caries. Here, we report a case of a patient exhibiting amelogenesis imperfecta, the treatment employed to treat the defects, and the result obtained. The affected teeth (all upper teeth) appeared white and the patient requested esthetic improvement of the appearance. We applied flowable composite resin to the hypomineralized defect. The result was dramatic improvement in tooth color of the upper incisors and first premolars. We conclude that atraumatic flowable composite resin restorations are useful in the treatment of amelogenesis imperfecta defects

Confocal microphotoluminescence of InGaN-based light-emitting diodes

Spatially resolved photoluminescence (PL) of InGaN/GaN/AlGaN-based quantum-well-structured light-emitting diodes (LEDs) with a yellow-green light (530 nm) and an amber light (600 nm) was measured by using confocal microscopy. Submicron-scale spatial inhomogeneities of both PL intensities and spectra were found in confocal micro-PL images. We also found clear correlations between PL intensities and peak wavelength for both LEDs. Such correlations for yellow-green and amber LEDs were different from the reported correlations for blue or green LEDs. This discrepancy should be due to different diffusion, localization, and recombination dynamics of electron-hole pairs generated in InGaN active layers, and should be a very important property for influencing the optical properties of LEDs. In order to explain the results, we proposed a possible carrier dynamics model based on the carrier localization and partial reduction of the quantum confinement Stark effect depending on an indium composition in InGaN active layers. By using this model, we also considered the origin of the reduction of the emission efficiencies with a longer emission wavelength of InGaN LEDs with high indium composition

Pyramidal Neurons of the Zebrafish Tectum Receive Highly Convergent Input From Torus Longitudinalis

The torus longitudinalis (TL) is a midbrain structure unique to ray finned fish. Although previously implicated in orienting behaviors elicited by changes in ambient lighting, the role of TL in visual processing is not well-understood. TL is reciprocally connected to tectum and is the only known source of synaptic input to the stratum marginalis (SM) layer of tectal neuropil. Conversely, tectal pyramidal neurons (PyrNs) are the only identified tectal neuron population that forms a dendrite in SM. In this study we describe a zebrafish gal4 transgenic that labels TL neurons that project to SM. We demonstrate that the axonal TL projection to SM in zebrafish is glutamatergic. Consistent with these axons synapsing directly onto PyrNs, SM-targeted dendrites of PyrNs contain punctate enrichments of the glutamatergic post-synaptic marker protein PSD95. Sparse genetic labeling of individual TL axons and PyrN dendrites enabled quantitative morphometric analysis that revealed (1) large, sparsely branched TL axons in SM and (2) small, densely innervated PyrN dendrites in SM. Together this unique combination of morphologies support a wiring diagram in which TL inputs to PyrNs exhibit a high degree of convergence. We propose that this convergence functions to generate large, compound visual receptive fields in PyrNs. This quantitative anatomical data will instruct future functional studies aimed at identifying the precise contribution of TL-PyrN circuitry to visual behavior