Influence of birefringence dispersion on distributed measurement of polarization coupling in birefringent fibers

A white light interferometer is developed to measure the distributed polarization coupling in high-birefringence polarization-maintaining fibers (PMFs). Usually the birefringence dispersion between two orthogonal eigenmodes of PMFs is neglected in such systems. Theoretical analysis and experimental results show that the birefringence dispersion becomes a nonnegligible factor in a long-fiber test. Significant broadening of interferograms and loss of longitudinal coherence are observed. The spatial resolution and measurement sensitivity of the system decrease correspondingly. Optimum spectrum width selection is presented for better spatial resolution and measurement range. c 2007 Society of Photo-Optical Instrumentation Engineers.

Multibeam coupling in photorefractive SBN:Ce

Theoretical and experimental results are presented for simultaneous multibeam coupling in photorefractive SBN:Ce. Within a single crystal, multiple signals are amplified through a coupling process that employs a single pump. The coupling gain of each signal results from coupling both between the pump and the signal and between different signals. The amount of gain that each signal receives is dependent on the intensity of the incident signal; thus a competition for the gain exists among the various signals.

Simple ABCD matrix method for evaluating optical coupling system of laser diode to single-mode fiber with a lensed-tip

In this paper, we present a simple technique to determine the coupling efficiency between a laser diode and a lensed-tip based on the ABCD transformation matrix method. We have compared our analysis technique to that of previous work and have found that the presented method is reliable in predicting the coupling efficiency of lensed-tip and has the advantage of simplicity of coupling efficiency calculation even by a pocket calculator. The results can be useful for designing coupling optics. (c) 2005 Elsevier GmbH. All rights reserved.

Influence of birefringence dispersion on distributed measurement of polarization coupling in birefringent fibers

A white light interferometer is developed to measure the distributed polarization coupling in high-birefringence polarization-maintaining fibers (PMFs). Usually the birefringence dispersion between two orthogonal eigenmodes of PMFs is neglected in such systems. Theoretical analysis and experimental results show that the birefringence dispersion becomes a nonnegligible factor in a long-fiber test. Significant broadening of interferograms and loss of longitudinal coherence are observed. The spatial resolution and measurement sensitivity of the system decrease correspondingly. Optimum spectrum width selection is presented for better spatial resolution and measurement range. c 2007 Society of Photo-Optical Instrumentation Engineers.

Prism coupling of ultrashort light pulses into waveguides

We discuss coupling of ultrashort light pulses into waveguides by use of a prism waveguide coupler configuration. Theoretical analysis indicates that an extra loss induced by the short coherence times of ultrashort pulses, which has a strong effect on the reflected light and the optimum coupling condition, appears in the waveguide. Numerical simulations show that the reflectance strongly depends on the coherence times of ultrashort pulses. A method for realizing optimum coupling by compensating for the extra loss is proposed as well in this paper. A preliminary experiment of employing ultrashort pulses with different coherence times was carried out, and good agreement between theory and experiment was obtained. (c) 2006 Optical Society of America.

Coupling efficiency of laser beam to multimode fiber

The coupling efficiency of laser beam to multimode fiber is given by geometrical optics, and the relation between the maximum coupling efficiency and the beam propagation factor M-2 is analyzed. An equivalent factor M-F(2) for the multimode fiber is introduced to characterize the fiber coupling capability. The coupling efficiency of laser beam to multimode fiber is calculated in respect of the ratio M-2/M-F(2) by the overlapping integral theory. The optimal coupling efficiency can be roughly estimated by the ratio of M-2 to M-F(2) but with a large error range. The deviation comes from the lacks of information on the detail of phase and intensity profile in the beam factor M-2. (C) 2007 Elsevier B.V. All rights reserved.

Toward an understanding of the molecular mechanism for successful blood feeding by coupling proteomics analysis with pharmacological testing of horsefly salivary glands

Horseflies are economically important blood-feeding arthropods and also a nuisance for humans and vectors for filariasis. They rely heavily on the pharmacological properties of their saliva to get a blood meal and suppress immune reactions of hosts. Little information is available on antihemostatic substances in horsefly salivary glands; especially no horsefly immune suppressants have been reported. By proteomics or peptidomics and coupling transcriptome analysis with pharmacological testing, several families of proteins or peptides, which act mainly on the hemostatic system or immune system of the host, were identified and characterized from 30,000 pairs salivary glands of the horsefly Tabanus yao (Diptera, Tabanidae). They are: (i) a novel family of inhibitors of platelet aggregation including two members, which possibly inhibit platelet aggregation by a novel mechanism and act on platelet membrane, (ii) a novel family of immunosuppressant peptides including 12 members, which can inhibit interferon-gamma production and increase interleukin-10 secretion, (iii) a serine protease inhibitor with 56 amino acid residues containing anticoagulant activity, (iv) a serine protease with anticoagulant activity, (v) a protease with fibrinogenolytic activity, (vi) three families of antimicrobial peptides including six members, (vii) a hyaluronidase, (viii) a vasodilator peptide, which is an isoform of vasotab identified from Hybomitra bimaculata, and interestingly (ix) two metallothioneins, which are the first metallothioneins reported from invertebrate salivary glands. The current work will facilitate the understanding of the molecular mechanisms of the ectoparasite-host relationship and help in identifying novel vaccine targets and novel leading pharmacological compounds.

Zinc coupling potentiates anti-HIV-1 activity of baicalin

Baicalin (BA) has been shown with anti-HIV-1 activity. Zinc is a nutrient element. The anti-HIV-1 activity of zinc complex of baicalin (BA-Zn) in vitro was studied and compared with the anti-HIV-1 activities between BA and BA-Zn in the present study. Our results suggested that BA-Zn has lower cytotoxicity and higher anti-HIV-1 activity compared with those of BA in vitro. The CC(50)s of BA-Zn and BA were 221.52 and 101.73 muM, respectively. The cytotoxicity of BA-Zn was about 1.2-fold lower than that of BA. The BA and BA-Zn inhibited HIV-1 induced syncytium formation, HIV-1 p24 antigen and HIV-1 RT production. The EC(50)s of BA-Zn on inhibiting HIV-1 induced syncytium formation (29.08 muM) and RT production (31.17 muM) were lower than those of BA (43.27 and 47.34 muM, respectively). BA-Zn was more effective than BA in inhibiting the activities of recombinant RT and HIV-1 entry into host cells. Zinc coupling enhanced the anti-HTV-1 activity of baicalin. (C) 2004 Elsevier Inc. All rights reserved.

Coupling between elytra of some beetles: Mechanism, forces and effect of surface texture

Lightweight materials, structures and coupling mechanisms are very important for realizing advanced flight vehicles. Here, we obtained the geometric structures and morphologies of the elytra of beetles and ascertained its coupling zone by using the histological section technique and SEM. We set up a three-dimensional motion observing system to monitor the opening and closing behaviour of elytra in beetles and to determine the motion mechanism. We constructed a force measuring system to measure the coupling forces between elytra. The results show that elytra open and close by rotating about a single axle, where the coupling forces may be as high as 160 times its own bodyweight, the elytra coupling with the tenon and mortise mechanism, surface texture and opening angle between elytra heavily influence the coupling forces. These results may provide insights into the design mechanism and structure for future vehicles of flight.

Coupling between NMDA receptor and acid-sensing ion channel contributes to ischemic neuronal death

Acid-sensing ion channels (ASICs) composed of ASIC1a subunit exhibit a high Ca2+ permeability and play important roles in synaptic plasticity and acid-induced cell death. Here, we show that ischemia enhances ASIC currents through the phosphorylation at Ser478 and Ser479 of ASIC1a, leading to exacerbated ischemic cell death. The phosphorylation is catalyzed by Ca2+/calmodulin-dependent protein kinase II (CaMKII) activity, as a result of activation of NR2B-containing N-methyl-D-aspartate subtype of glutamate receptors (NMDARs) during ischemia. Furthermore, NR2B-specific antagonist, CaMKII inhibitor, or overexpression of mutated form of ASIC1a with Ser478 or Ser479 replaced by alanine (ASICla-S478A, ASIC1a-S479A) in cultured hippocampal neurons prevented ischemia-induced enhancement of ASIC currents, cytoplasmic Ca2+ elevation, as well as neuronal death. Thus, NMDAR-CaMKII cascade is functionally coupled to ASICs and contributes to acidotoxicity during ischemia. Specific blockade of NMDAR/CaMKII-ASIC coupling may reduce neuronal death after ischemia and other pathological conditions involving excessive glutamate release and acidosis.

HORMONAL-REGULATION OF TISSUE-TYPE PLASMINOGEN-ACTIVATOR AND PLASMINOGEN-ACTIVATOR INHIBITOR TYPE-1 IN CULTURED MONKEY SERTOLI CELLS

Sertoli cells play a central role in the control and maintenance of spermatogenesis. Isolated Sertoli cells of mouse and rat testes have been shown to secrete plasminogen activator (PA) and a plasminogen activator inhibitor type-1 (PAI-1) in culture. In this study, we have investigated the hormonal regulation of PA and PAI-1 activities in cultured monkey Sertoli cells. Sertoli cells (5x10(5) cells/well) isolated from infant rhesus monkey testes were preincubated at 35 degrees C for 16 h in 24-well plates precoated with poly(D-lysine) (5 mu g/cm(2)) in 0.5 mi McCoy's 5a medium containing 5% of fetal calf serum and further incubated for 48 h in 0.5 mi serum-free medium with or without various hormones or other compounds, PA as well as PAI-1 activities in the conditioned media were assayed by fibrin overlay and reverse fibrin autography techniques respectively. The Sertoli cells in vitro secreted only tissue-type PA (tPA), no detectable amount of urokinase-type PA (uPA) could be observed, Monkey Sertoli cells were also capable of secreting PAI-1, Immunocytochemical studies indicated that both tPA and PAI-1 positive staining localized in the Sertoli cells, spermatids and residual bodies of the seminiferous epithelium; Northern blot analysis further confirmed the presence of both tPA and PAI-1 mRNA in monkey Sertoli cells. Addition of follicle-stimulating hormone (FSH) or cyclic adenosine monophosphate (cAMP) derivatives or cAMP-generating agents and gonadotrophin-releasing hormone (GnRH) agonist or phorbol ester (PMA) to the cell culture significantly increased tPA activity. PAI-1 activity in the culture was also enhanced by these reagents except 8-bromo-dibutyryl-cAMP, forskolin and 3-isobutyl-1-methylxanthin (MIX) which greatly stimulated tPA activity, whereas decreased PAI-1 activity, implying that neutralization of PAI-1 activity by tile high level of tPA in the conditioned media may occur. These data suggest that increased intracellular signals which activate protein kinase A (PKA), or protein kinase C (PKC) can modulate Sertoli cell tPA and PAI-1 activities, The concomitant induction of PA and PAI-1 by the same reagents in the Sertoli cells may reflect a finely tuned regulatory mechanism in which PAI-1 could limit the excession of the proteolysis.

HORMONAL REPLACEMENT THERAPY IN FISH - HUMAN GROWTH-HORMONE GENE-FUNCTION IN HYPOPHYSECTOMIZED CARP

Transgenic common carp, Cyprinus carpio, produced by the microinjection of fertilized eggs with a linearized chimeric plasmid pMThGH, a human growth hormone (hGH) gene with a mouse metallothionein-I (MT) gene promoter in pBR322, were used to produce F1 and F2 transgenics. Following hypophysectomy of the transgenic F2 common carp, non-transgenic common carp and non-transgenic crucian carp, growth was monitored for up to 110 days. In addition, recombinant hGH was injected subcutaenously into a group of the non-transgenic crucian carp. Growth rate analyses indicated that (1) hypophysectomy of non-transgenic common carp and crucian carp results in the cessation of growth, (2) hGH administration can stimulate the growth of hypophysectomized crucian carp and (3) hypophysectomized hGH-transgenic common carp continue to grow in the absence of their own growth hormone, suggesting that the hGH-transgene is being expressed in tissues other than the pituitary.