Influence of a ring-shaped pump beam on temperature distribution and thermal lensing in end-pumped solid state lasers.

A simple method for reducing thermal lensing in an end-pumped solid state laser using a ring-shaped pump beam is reported. Analytical expressions for the temperature distribution and the thermal lensing focal length in a laser medium end-pumped by a beam with a ring-shaped intensity profile are derived. The results indicate that thermal effects including thermal lensing can be significantly reduced due to a more uniform temperature distribution. This approach has been applied to a Nd:YVO4 amplifier operating at 1064 nm confirming that the brightness of the output beam can be remarkably improved at high power levels due to the better beam quality for the ring-shaped pumping compared to the conventional quasi-top-hat pumping. The prospects for power scaling and further improvement in laser performance will be discussed.

Analysis of comedone, sebum and porphyrin on the face and body for comedogenicity assay.

BACKGROUND/PURPOSE: Many ingredients used in cosmetics evoke a comedogenic response. Rabbit ear model (REM) is a useful method that can replace human in examining materials and products in early developmental stage. However, a number of studies pointed out its disadvantage that it overreacts to comedogenic materials. The purpose of this study was to find the most appropriate region for evaluating comedogenicity in human skin. METHODS: Sixty-six female subjects (age 32.48 ± 10 years; range 20-52 years) with mild to moderate facial acne lesions were included in this study. The whole face, upper chest, and back of volunteers were photographed. Lesion (closed and open comedones) counting, instrumentation of sebum secretion level, and analysis of porphyrin number were performed. The entire study was performed under environmental conditions of specific relative temperature and humidity, controlled and maintained identically for each volunteer. RESULTS: In case of closed comedone, forehead showed a significant correlation with frontal cheek, lateral cheek, chin, and upper back. Meanwhile, significant correlations were observed between frontal cheek and chin as well as lateral cheek and chest. As for open comedone, forehead showed a significant correlation with chin site. A significant correlation was also observed between front cheek and lateral cheek as well as between upper chest and back. Analyzing the correlation between the occurrence of comedones and sebum in each region, a significant correlation between closed comedone and sebum was observed in frontal and lateral cheek. Analyzing the correlation between the occurrence of comedones and porphyrine in each region, a significant correlation between open comedone and porphyrin was observed in chin. CONCLUSION: When evaluating the comedogenicity of cosmetics ingredients or products, this study recommends using both of the methods of testing on back and directly testing on face according to the characteristics of the materials. In case of mild potent ingredients or products in particular, verification through usability test that the directly test on face will help securing reliability.

Smad3 regulates E-cadherin via miRNA-200 pathway.

To identify potential microRNA (miRNA) links between Smad3, a mediator of TGF-ß (transforming growth factor-ß) signaling, and E-cadherin, we characterized the miRNA profiles of two gastric cancer cell lines: SNU484-LPCX, which does not express Smad3, and SNU484-Smad3, in which Smad3 is overexpressed. We found that among differentially expressed miRNAs, miR-200 family members are overexpressed in SNU484-Smad3 cells. Subsequent studies, including analysis of the effects of silencing Smad3 in SNU484-Smad3 cells and a luciferase reporter assay, revealed that Smad3 directly binds to a Smad-binding element located in the promoter region of miR-200b/a, where it functions as a transcriptional activator. TGF-ß did not affect the regulatory role of Smad3 in transcription of miR-200 and expression of epithelial-mesenchymal transition markers. We conclude that Smad3 regulates, at the transcriptional level, miR-200 family members, which themselves regulate ZEB1 and ZEB2, known transcriptional repressors of E-cadherin, at the posttranscriptional level in a TGF-ß-independent manner. This represents a novel link between Smad3 and posttranscriptional regulation by miRNAs in epithelial-mesenchymal transition in gastric cancer cells.

Translational positioning of a magnetic domain wall in ferromagnetic nanowires using a stray field filter.

Understanding the interaction between the magnetic domain wall and the various artificial defects in ferromagnetic nanowires has been of utmost importance for the future realization of the spintronic devices based on the magnetic domain wall motion in nanowires. In this work, the chirality filter effect of the magnetic domain wall in T-shaped ferromagnetic nanowires with a stray field filter was investigated via micromagnetic simulation. A tapered wire was attached to the flat nanowires to form a potential barrier or well for the domain wall propagating along them. For the domain wall passing through the potential barrier or the potential well, the spin structure of the domain wall and the interaction between the domain wall and the potential barrier/well were investigated in detail. The chirality-dependent translational positioning of the domain wall was intensively examined for the potential barrier and potential well cases. The domain wall chirality transmission on relatively long length scales using a series of potential wells was explored.

Alterations in AMPA receptor phosphorylation in the rat striatum following acute and repeated cocaine administration.

Protein phosphorylation is an important mechanism for the posttranslational modulation of ionotropic glutamate receptors and is subject to regulation by changing synaptic inputs. In this study, we investigated the regulation of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor GluR1 subunit phosphorylation by cocaine exposure in the rat dorsal striatum in vivo. We found that acute cocaine challenge followed by 6 days of repeated systemic injections of cocaine (20 mg/kg once daily) enhanced the sensitivity of the GluR1 subunit in its phosphorylation at serine 831 (Ser831) in the dorsal striatum. This enhancement of the sensitivity of Ser831 phosphorylation was reduced, at the receptor and ion channel level, by blocking (1) group I metabotropic glutamate receptors (mGluRs), (2) N-methyl-D-aspartate receptors, and (3) L-type voltage-operated Ca(2+) channels. Similar reduction of the enhancement was also induced, at the protein kinase level, by inhibiting (1) protein kinase C, (2) calcium/calmodulin-dependent protein kinases, and (3) c-Jun N-terminal kinases. In addition, inhibition of protein phosphatase 1/2A or calcineurin increased GluR1-Ser831 phosphorylation in the dorsal striatum of normal rats, whereas inhibition of these phosphatases did not further enhance the Ser831 phosphorylation in rats pretreated with 7 daily injections of cocaine. These data suggest that the phosphorylation of AMPA receptor GluR1 subunits at Ser831 is subject to upregulation by acute and repeated cocaine administration. Complex signaling integrations among glutamate receptors, Ca(2+) channels, protein kinases, and protein phosphatases participate in this upregulation.

Yeast thiol-dependent protector protein expression enhances the resistance of Escherichia coli to hydrogen peroxide.

A soluble protein from Saccharomyces cerevisiae specifically provides protection against a thiol-containing oxidation system but not against an oxidation system without thiol. This 25-kDa protein was thus named thiol-dependent protector protein (TPP). The role of TPP in the cellular defense against oxidative stress was investigated in Escherichia coli containing an expression vector with a yeast genomic DNA fragment that encodes TPP (strain YP) and mutants in which the catalytically essential amino acid cysteine (Cys-47) has been replaced with alanine (strain YPC47A) or tryptophan (Trp-82) has been replaced with phenylalanine (strain YPW82F) by a site directed mutagenesis. There was a distinct difference between these three strains in regards to growth inhibition kinetics, viability, modulation of activities of superoxide dismutase and catalase, and the accumulation of oxidized proteins. These results suggest that TPP may play a direct role in the cellular defense against oxidative stress by functioning as an antioxidant protein.

Translocation of recombinant p47phox cytosolic component of the phagocyte oxidase by in vitro phosphorylation.

Activation of superoxide-generating NADPH oxidase system of human neutrophils involves phosphorylation-dependent translocation of p47phox and other cytosolic components to the plasma membrane. In contrast to the stimulation of the NADPH oxidase in intact cells, however, the activation of cell-free system requires the addition of anionic amphiphiles such as sodium dodecyl sulfate (SDS) and arachidonate. In this system, translocation of p47phox is also an essential step for activation, but phosphorylation is not required. The basis of this difference in oxidase activation is not yet clear. We now report that in a cell-free oxidase system, phosphorylated recombinant p47phox can be translocated to the membrane in the absence of SDS or arachidonate. These findings suggest that both phosphorylation and SDS could cause a common change in conformation or charge of p47phox that may result in the association of p47phox with the plasma membrane.

A computer algorithm for spatio-temporal patterns in interactive neuron populations.

A computer algorithm has been developed which enables numerical computations to be performed for interactive neuron populations whose spatio-temporal behaviors are represented by a set of certain integro-differential equations. The computation is based on the fact that the eigenfunctions of a symmetric Hilbert-Schmidt operator form a set of complete orthonormal functions in L2 space. This algorithm differs from the ones which computes the value of the solution at each (x,t) point in that it computes the coefficients corresponding to the eigenfunctions. Therefore it is shown that the error in the coefficient of one eigenfunction does not propagate to that of another eigenfunction from one sampling time to the next one. This enables us to analyze the temporal behavior of one spatial frequency which is not affected by that of the other spatial frequencies.