Neonatal ureteral obstruction stimulates recruitment of renin-secreting renal cortical cells

Neonatal ureteral obstruction stimulates recruitment of renin-secreting renal cortical cells. Unilateral ureteral obstruction (UUO) in the neonate increases ipsilateral renal renin gene expression, an effect which is mediated by renal nerves. To determine whether neonatal UUO alters the number of renal cortical cells secreting renin and whether this change is modulated by renal nerve activity, newborn Sprague-Dawley rats were subjected to left UUO, right uninephrectomy, or sham operation and studied four weeks thereafter. To evaluate the importance of renal nerves in this response, an additional group of animals underwent chemical sympathectomy with guanethidine. Ureteral obstruction was associated with marked reduction in renal mass in the obstructed kidney and contralateral compensatory hypertrophy, changes which were not altered by sympathectomy. Renin messenger RNA and renal renin content were elevated in the obstructed kidney. The number of cells secreting renin, measured by the reverse hemolytic plaque assay, was markedly increased in the obstructed kidney (45 ± 18 plaques/slide vs. 11 ± 1 plaques/slide in sham animals), but not in the opposite kidney or following uninephrectomy. This effect was not significantly altered by sympathectomy. There was no change in the amount of renin secreted per cell or in the secretory response to Ca++. These results show that UUO results in recruitment of cells not previously secreting renin by a mechanism independent of renal nerve activity. This recruitment occurs without alteration of the quantity of renin secreted per cell or in the normal regulatory effect of Ca++ on renin secretion. An increase in the number of renin-secreting cells may contribute to the activation of the renin-angiotensin system, and thus to the vasoconstriction observed following ureteral obstruction

High-performance photorefractive polymer operating at 1550 nm with near-video-rate response time

© 2005 American Institute of Physics. The electronic version of this article is the complete one and can be found at: http://dx.doi.org/10.1063/1.2117610DOI: 10.1063/1.2117610The development of a high-performance photorefractive polymer composite operating at 1550 nm is reported. We show 40% internal diffraction efficiency with response time of 35 ms and a net gain of 20 cm ⁻¹ in four-wave mixing and two-beam coupling experiments, respectively. This is more than an order of magnitude improvement in the diffraction efficiency and net two beam coupling gain and two orders of magnitude in the response time than the previously reported photorefractive polymer operating at this technologically important wavelength. The improvement in photorefractive characteristics is accomplished by an enhanced orientation of the nonlinear optical chromophore in the present composit

Nanolaminate structures fabricated by ALD for reducing propagation losses and enhancing the third-order optical nonlinearities

We demonstrate a novel atomic layer deposition (ALD) process to make high quality nanocrystalline titanium dioxide (TiO2) and zinc oxide (ZnO) with intermediate Al2O3 layers to limit the crystal size. The waveguide losses of TiO2/Al2O3 nanolaminates measured using the prism coupling method for both 633 nm and 1551 nm wavelengths are as low as 0.2 ± 0.1 dB/mm with the smallest crystal size. We also show that the third-order optical nonlinearity in ZnO/Al2O3 nanolaminates can be enhanced by nanoscale engineering of the thin film structure.Peer reviewe

Silicone optical elements for cost-effective freeform solar concentration

The use of silicone optical elements is demonstrated for a concentrated photovoltaic system. These components show over 96% transmission through most of the solar spectrum and excellent temperature stability. Unique moldability enables the use of complex freeform designs. A light, compact, and cost-effective concentrated photovoltaic system based on silicone optics is proposed. In this system, air-plasma treatment is utilized to overcome the mechanical properties of silicone and difficulties with coating to reduce Fresnel loss. Lens arrays and waveguides are fabricated by injection molding following freeform optical design by LightTools. First-order characterizations are also performed. (c) 2019 Optical Society of America under the terms of the OSA Open Access Publishing AgreementAdvanced Research Projects Agency-Energy (ARPA-E) MOSAIC program [DE-AR0000839]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Planar photonic crystals infiltrated with nanoparticle/polymer composites

© 2007 American Institute of Physics. The electronic version of this article is the complete one and can be found at: http://dx.doi.org/10.1063/1.2817964DOI: 10.1063/1.2817964Infiltration of planar two-dimensional silicon photonic crystals with nanocomposites using a simple yet effective melt processing technique is presented. The nanocomposites that were developed by evenly dispersing functionalized TiO₂ nanoparticles into a photoconducting polymer were completely filled into photonic crystals with hole sizes ranging from 90 to 500 nm. The infiltrated devices show tuning of the photonic band gap that is controllable by the adjustment of the nanoparticle loading level. These results may be useful in the development of tunable photonic crystal based devices and hybrid light emitting diodes and solar cells

Numerical investigation of GHz repetition rate fundamentally mode-locked all-fiber lasers

GHz repetition rate fundamentally mode-locked lasers have attracted great interest for a variety of scientific and practical applications. A passively mode-locked laser in all-fiber format has the advantages of high stability, maintenance-free operation, super compactness, and reliability. In this paper, we present numerical investigation on passive mode-locking of all-fiber lasers operating at repetition rates of 1-20 GHz. Our calculations show that the reflectivity of the output coupler, the small signal gain of the doped fiber, the total net cavity dispersion, and the modulation depth of the saturable absorber are the key parameters for producing stable fundamentally mode-locked pulses at GHz repetition rates in very short all-fiber linear cavities. The instabilities of GHz repetition rate fundamentally mode-locked all-fiber lasers with different parameters were calculated and analyzed. Compared to a regular MHz repetition rate mode-locked all-fiber laser, the pump power range for the mode-locking of a GHz repetition rate all-fiber laser is much larger due to the several orders of magnitude lower accumulated nonlinearity in the fiber cavity The presented numerical study provides valuable guidance for the design and development of highly stable mode-locked all-fiber lasers operating at GHz repetition rates.National Science Foundation Engineering Research Center for Integrated Access Networks [EEC-0812072]; Technology Research Initiative Fund (TRIF) Photonics Initiative of the University of Arizona; National Natural Science Foundation of China (NSFC) [61575075]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Engineered nonlinear materials using gold nanoantenna array

Gold dipole nanoantennas embedded in an organic molecular film provide strong local electromagnetic fields to enhance both the nonlinear refractive index (n(2)) and two-photon absorption (2PA) of the molecules. An enhancement of 53x for 2PA and 140x for nonlinear refraction is observed for BDPAS (4,4'-bis(diphenylamino) stilbene) at 600 nm with only 3.7% of gold volume fraction. The complex value of the third-order susceptibility enhancement results in a sign change of n(2) for the effective composite material relative to the pure BDPAS film. This complex nature of the enhancement and the tunability of the nanoantenna resonance allow for engineering the effective nonlinear response of the composite film8119Agências de fomento estrangeiras apoiaram essa pesquisa, mais informações acesse artig

The Problem of Experience in the Study of Organizations

This paper deals with the fact that we cannot experience large organizations directly, in the same way as we can experience individuals or small groups, and that this non-experientiability has certain implications for our scientific theories of organizations. Whereas a science is animated by a constructive interplay of theory concepts and experience concepts, the study of organizations has been confined to theory concepts alone. Implications of this analysis for developing a science of organizations are considered.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68303/2/10.1177_017084069301400102.pd