Use of a doubly polarized laser for remote powering of anintegrated optical modulator

Stable operation of an integrated optic modulator is demonstrated using a 1.3 μm doubly polarized laser as a depolarized source in conjunction with a long run of ordinary fiber. The laser is found to be unusually susceptible to feedback due to gain competition between the polarization modes. The resulting low-frequency polarization noise is significantly reduced by the addition of fiber isolators to the system     

Effect of intrinsic phase mismatch on linear modulator performanceof the 1×2 directional coupler and Mach-Zehnderinterferometer

The performance of 1×2 directional couplers and Mach-Zehnder interferometers as linear modulators is compared. Models describing the operation of each device, incorporating the intrinsic phase mismatch Δβ₀ which is present in nonideal devices, are developed. Distributions of Δβ₀ are obtained for each device and are shown to be independent of device type. Linear dynamic range and sensitivity measurements showing how Δβ₀ affects performance agree with theory. The additional effect of the coupling coefficient in the 1×2 directional coupler is demonstrated. This information can be used to predict device yield when combined with the measured Δβ₀ distributions     

Growth of high-quality carbon nanotubes on free-standing diamond substrates

Carbon nanotubes (CNTs) were grown on diamond-coated Si substrates and free-standing diamond wafers to develop efficient thermal interface materials for thermal management applications. High-quality, translucent, free-standing diamond substrates were processed in a 5 kW microwave plasma chemical vapor deposition (CVD) system using CH₄ as precursor. Ni and Ni-9%W-1.5%Fe catalyst islands were deposited to nucleate CNTs directly onto the diamond substrates. Randomly-oriented multi-walled CNTs forming a mat of ∼5 μm thickness and consisting of ∼20 nm diameter tubes were observed to grow in a thermal CVD system using C₂H₂ as precursor. Transmission electron microscopy and Raman analyses confirmed the presence of high-quality CNTs on diamond showing a D/G peak ratio of 0.2-0.3 in Raman spectra.     

Effect of combined heat, ozonation and ultraviolet irradiation (VasoCare) on heat shock protein expression by peripheral blood leukocyte populations

The re-administration of whole blood subjected to heat, ozonation and ultraviolet irradiation (VasoCare therapy) has been shown to elicit clinical benefits in individuals with vascular disease. Given that these stressors induce heat shock protein (Hsp) expression and that heat shock protein reactivity is implicated in the pathogenesis of vascular disease, this study assessed the effect of VasoCare on intracellular expression of Hsp60 and Hsp70 by treated peripheral blood leukocytes. Contrary to expectations, VasoCare induced a significant reduction (approximately 40%) in the proportion of peripheral blood mononuclear cells expressing intracellular Hsp60 and Hsp70, whereas it had no effect on heat shock protein expression by peripheral blood neutrophils. Cell surface heat shock protein expression was not detectable. The reduced expression of Hsp60 by mononuclear cells was concomitant with an increase in the levels of Hsp60 in treated plasma. Although the mechanism underlying the clinical effectiveness of VasoCare therapy has yet to be established, it may be that re-administration of treated blood or soluble factors derived therefrom modifies in vivo immune responsiveness to heat shock proteins or associated molecules.     

Supervision: how it works

While much has been written about the value of clinical supervision and theoretical models of how it should take place, few accounts exist of how it works in practice. This paper illustrates how supervision was implemented within a directorate in one trust. Both pitfalls and successes of the project are highlighted together with a summary of the evaluation. Evaluation demonstrated that two-thirds of those receiving supervision valued it highly.     

Control of first-wall surface conditions in the 2XIIB magnetic mirror plasma confinement experiment

The control of first-wall surface conditions in the 2XIIB Magnetic Mirror Plasma Confinement experiment is described. Before each plasma shot, the first wall is covered with a freshly gettered titanium surface. Up to 5 MW of neutral beam power has been injected into 2XIIB, resulting in first-wall bombardment fluxes of 10¹⁷ atoms · cm^?2 · s^?1 of 13-keV mean energy deuterium atoms for several ms. The background gas flux is measured with a calibrated, 11-channel, fast-atom detector. Background gas levels are found to depend on surface conditions, injected beam current, and beam pulse duration. For our best operating conditions, an efective reflex coefficient of 0.3 can be inferred from the measurements. Experiments with long-duration and high-current beam injection are limited by charge exchange; however, experiments with shorter beam duration are not limited by first-wall surface conditions. We conclude that surface effects will be reduced further with smoother walls.     

Immunohistochemical characterization of proliferation, oestrogen receptor and progesterone receptor expression in endometriosis: comparison of eutopic and ectopic endometrium with normal cycling endometrium

Recent studies examining oestrogen and progesterone receptor status and the proliferative activity of endometriotic lesions have produced conflicting reports. This study aimed to clarify the receptor status and proliferative activity of eutopic and ectopic endometrium from women with endometriosis and endometrium from normal women. Progesterone and oestrogen receptor expression and proliferative activity were studied in eutopic and ectopic endometrium from 30 women with endometriosis and in endometrium from 30 normal cycling women using microwave-pretreated paraffin-embedded sections stained with an avidin-biotin peroxidase technique. Progesterone and oestrogen receptor expression in the control endometrium did not differ from that of eutopic endometrium from women with endometriosis. Oestrogen receptor expression in ectopic endometrium increased from the proliferative to the late secretory phase. Epithelial progesterone receptor expression decreased during the cycle. Oestrogen receptor expression in both epithelium and stroma of ectopic endometrium was significantly higher than in eutopic endometrium throughout the cycle. In contrast, stromal progesterone receptor expression tended to be reduced in ectopic endometrium compared with eutopic tissue. Epithelial progesterone receptor expression was increased in ectopic endometrium but only in the late secretory phase. Although proliferative activity in the epithelium of control and eutopic endometrium was reduced from the proliferative to the late secretory phase, stromal activity did not vary. The proliferative activity in ectopic endometrium remained low and constant throughout the cycle. In the proliferative and early secretory phases, the proliferative activity of eutopic endometrium was increased compared with ectopic endometrium, but in the late secretory phase, levels were comparable. These findings challenge previous reports which have suggested that oestrogen receptors are reduced in ectopic tissue. This may have clinical implications for the development of novel treatments for endometriosis.     

Performance and modeling of broadband LiNbO3 travelingwave optical intensity modulators

The design, fabrication and characterization of a traveling wave Ti:LiNbO₃ Mach-Zehnder interferometric modulator are discussed. The dependence of the velocity match condition on electrode thickness and wall angle is demonstrated experimentally and with finite element calculations. A set of test electrode structures is fabricated to study electrical losses in the modulator electrode. Loss coefficients are assigned to different sections of the device, and dielectric and radiative losses are shown to play an important role at high frequencies. This information is used in conjunction with finite-element calculations to develop accurate models for both the electrical and optical responses. The frequency dependence of the half-wave voltage is measured and shown to be in good agreement with a model     

Characterization of Ti:LiNbO3 deep waveguides diffused in dry and wet oxygen ambient

The diffusivity of thicker than usual Ti films into LiNbO3 to create deep waveguides has been investigated as a function of crystal orientation and diffusion ambient for temperatures ranging from 1050 to 1100 degrees C. The diffusion parameters for substrates diffused in water vapor environment are always larger than ones diffused in dry ambient. Differences in the diffusion coefficient for the extraordinary mode as high as 90, 66, and 84% are measured for X-, Y-, and Z-cut crystals, respectively. Smaller but noticeable differences are detected for the ordinary mode. Similar enhancing effects of the water vapor are also obtained for the surface-index change. Severe rough surface finish and surface contouring, revealing an etchedlike appearance, are observed on Z-cut substrates diffused in wet atmosphere. In general, substrates diffused in dry O2 produced relatively smoother surfaces. No outdiffused modes are excited in Z-cut substrates when diffused in dry oxygen ambient for long times at high temperatures.     

Use of a formal notation for static semantics in compiler design

Formal notations for the specification of the syntax and the dynamic semantics of languages exist and are of great benefit to the compiler writer. However, formal notations for the static semantics of languages have tended to be tools of the language designer and of little practical significance to the compiler writer. This paper describes how a particular notation was used to assist in the implementation of a Cobol compiler and of an interpreter for a simulation language.