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We demonstrate an extended reach 60 km coarse wavelength division multiplexing (CWDM)-time division multiple access (TDMA) passive optical network (PON) with 40 Gb/s capacity for both down and upstream directions. The system leverages existing 10 Gb/s TDMA PON technologies and incorporates various subsystems such as volume manufacturable optical transmitters, a prototype 10 Gb/s burst-mode receiver, hybrid semiconductor optical amplifier-Raman amplifiers, and a cyclic CWDM multiplexer. We confirm that this 32-user system has sufficient power margin to accommodate 128 users.

Bonding-induced strain is shown to have significant impact on the performance of distributed feedback (DFB) lasers mounted p-side up on AlN carriers using AuSn solder. Degree of polarization (DOP) of photoluminescence was used to estimate top-side longitudinal strain profiles in InP chips soldered to AlN carriers. Asymmetric strain profiles were revealed, the orientation of which are shown to be dependent on bonding tool coplanarity. Solder profiles measured on the same chips by scanning electron microscopy (SEM) were found to be nonuniform. Finite-element method (FEM) simulations were used to confirm that the asymmetric strain profiles resulted from solder nonuniformity caused by the bonding process. The FEM simulations were extended to analyze the effects of various bonding parameters on the top-side longitudinal strain profiles in InP chips, and suggestions are made for minimizing strain variations. The measured strains were included in a DFB laser model, and are shown to cause changes in slope efficiency and threshold current. These changes in slope efficiency and threshold current with bonding compare well with data collected from a large ensemble of DFB laser devices measured before and after the mounting process.

We report on a fully functional 2.5-Gb/s electroabsorption (EA)-modulated wavelength-selectable laser module meeting all long-haul transmission requirements for stability, chirp, power and linewidth over 20 channels on a 50-GHz grid. Based on a highly integrated InP chip comprising a distributed Bragg reflector (DBR) laser, semiconductor optical amplifier, power monitor, and EA-modulator, the compact transmitter module also contains optics and control circuits necessary to ensure simultaneous long-term wavelength and mode stability. We have achieved 2.5-Gb/s transmission on all 20 channels over 680 km of standard fiber.

We describe a protocol for assessing aging in the tuning section of a multisection distributed Bragg reflector laser integrated with amplifier, tap coupler, and electro-absorption modulator. Under accelerated aging, we observe a transient change of nonradiative recombination followed by saturation. A simple model of aging of the Bragg section of the tunable lasers enables prediction of changes in each wavelength channel using information obtained from a single channel only.

The synthesis and field-effect transistor (FET) electron mobility of ten N-substituted naphthalene 1,4,5,8-tetracarboxylic diimide (NTCDI) derivatives deposited at ambient and elevated temperatures are reported. Mobilities >0.01 cm2/(V s) were measured in air for three NTCDIs with partially fluorinated substituents, and >0.001 cm2/(V s) for a hydroxy-terminated compound. Mobilities 0.001−0.1 cm2/(V s) were also found for three n-alkyl NTCDIs, but only under vacuum; FET operation with gold bottom contacts was enabled by specific thiol coatings of the contacts. The highest mobility in air, >0.1 cm2/(V s), was conferred by 4-trifluoromethylbenzyl substitution, while 1H,1H-perfluorooctyl substitution resulted in an on/off ratio in air >105. Solution electrochemistry and solid-state X-ray and electron diffraction were employed to partially explain the results, and applications of the materials to complementary circuits are considered.

We describe the design, fabrication, and performance of a five-element quarterwave-shifted distributed feedback laser array with monolithically integrated spot size converters intended for use as a multiple-wavelength source in dense wavelength-division telecommunications systems. Facet power in excess of 10 mW with less than 150 mA bias and longitudinal side mode suppression greater than 40 dB were routinely achieved. Narrow far-field full-width at half-maximum angles of 6.9/spl deg//spl times/16.3/spl deg/ provided 3.5-dB coupling loss into single-mode fiber with 1.0-dB misalignment tolerances of /spl plusmn/2.0 /spl mu/m. With /spl plusmn/10/spl deg/C thermal tuning, 22 1555-nm channels spaced by 50 GHz were accessed with this device. Thorough field evaluation indicates that such a device is consistent with manufacturing requirements.

We have demonstrated a semiconductor optical amplifier and electroabsorption modulator monolithically integrated with a novel dual-waveguide spot-size converter at the input for low-loss coupling to planar lightguide circuit silica waveguides or cleaved single-mode optical fiber. These devices exhibit greater than 10 dB fiber-to-fiber gain, output power of +4 dBm, 3-dB modulation bandwidth of 6 GHz, and modulator extinction ratios of 20 dB dc and 14.4 dB RF for a 2.4-V/sub pp/ drive.

We describe a method for analyzing reflections within or near semiconductor lasers and more complicated integrated sources. Through Fourier transformation of an optical spectrum from the wavevector to the length domain, reflections are analyzed for strength, round-trip path length, and current or voltage dependence. Identification of reflections from within semiconductor lasers, integrated electro-absorption modulated lasers, and from coupling optics is presented. Spatial resolution in InP of /spl sim/5 /spl mu/m with over two orders of magnitude in dynamic range is demonstrated. Inverse transformation of a spatially resolved feature in a transformed reflection spectrum provides an optical spectrum due to that individual feature of sufficient resolution to study wavelength dependence, for example, of coatings and gratings.

A predistortion circuit with adjustable amounts of third- and fifth-order predistortion is studied both theoretically and experimentally. The circuit is used to cancel the third- and fifth-order intermodulation distortion of a 1.55-/spl mu/m integrated electroabsorption modulator/DFB laser. The CSO obtained is -61 dBc and the CTB is reduced 22.6 dB to -65 dBc. This performance is maintained after fiber amplification and propagation through 13 km of nondispersion shifted fiber due to the modulator's low chirp. Dithering of the DFB laser's injection current is employed to increase the stimulated Brillouin scattering (SBS) threshold to +13.4 dBm.

Exposure to soil‐borne contaminants can occur through ingestion, inhalation and/or dermal absorption. A study was undertaken to assess the relative frequency with which dermal exposures are predicted to pose the greatest risk attributable to contaminated soils in Superfund risk assessments. Screening of over 200 risk assessments from the period 1989–1992 resulted in identification of 37 sites at which projected lifetime excess cancer risks attributed to dermal contact with soil were greater than the nominal regulatory threshold of 1.10‐4. At 19 of these sites, the dermal/soil pathway is estimated to contribute the largest carcinogenic risk associated with surface soil contamination, and may therefore drive cleanup of that medium. At 9 of the sites, the dermal/soil pathway is predicted to present a higher carcinogenic risk than any other pathway. Chemical contaminant type and estimates of soil adherence and surface area exposed appear to be the primary factors that distinguish sites at which derma...

Twenty-two adult diabetic patients with clinical suspicion of foot and/or ankle infection were prospectively evaluated using radiography, technetium-99m methylene diphosphonate bone scanning (99Tc), indium-111-labeled leukocyte scanning (111In), and gallium-67 scanning (67Ga) to determine the presence of clinically suspected osteomyelitis.Biopsy for culture and histology was performed in 16 patients. The diagnosis of osteomyelitis was confirmed by biopsy in 12 patients. The remaining 10 patients had no evidence of osteomyelitis with long-term follow-up.99mTc was snown to be of limited valued when used alone in these patients with peripheral neuropathy.67Ga, either alone or in combination with99mTc bone scanning, was of little diagnostic value and gave no additional information that was not available from111In.The combination of three-phase99mTc and111In had the highest diagnostic efficacy (100% sensitivity, 80% specificity, and 91% accuracy), followed closely by111In alone (100% sensitivity, 70% specificity, and 86% accuracy).We conclude that for adult diabetic patients with clinical suspicion of osteomyelitis but no radiographic findings of that disease,111In alone is an appropriate nuclear medicine evaluation for ruling out infection if it is negative. However, if an area of111In white blood cell uptake is present, a “simultaneous”99mTc is often helpful in providing the anatomic correlation to differentiate osteomyelitis from infection that is limited to soft tissue.

Animal physiology graduate students provide an excellent personnel resource for laboratories performing human assisted reproductive technology (ART procedures. However, the basic training of these students falls short of what is required for this highly specialized field. We designed a course to enhance their education in this area via classroom and hands-on laboratory instruction in a hospital and university setting. Topics covered in the course included in vitro maturation, in vitro fertilization, embryo culture, embryo transfer, quality control, quality assurance, micromanipulation, and cryopreservation. These techniques were applied to a group project to evaluate the influence of spermatozoal quality and quantity on early embryonic development in cattle and humans. Student grades were based on 1) oral and written examinations ; 2) demonstrated competency in laboratory techniques ; 3) presentation of class project data at a state academy of science meeting ; and 4) initiative, determination, and interest in the coursework. Three aspects of the course stood out as very positive. First, the team approach to accomplishing a class project was new to some of the graduate students. Second, a bond was formed between hospital- and university-based faculty that did and will continue to foster unique teaching and research opportunities between the two groups. Third, the opportunity for students to present research data in a formal setting was very rewarding. This course made the students keenly aware of the many aspects of ART and provided them with specialized skills that should make them more marketable in the field of reproductive technology.

We report a method for depositing clean, uniform and stable SiOx dielectric films with high control and reproducibility. The technique uses a molecular or chemical beam epitaxy system (MBE or CBE). The technique offers many advantages over the conventional methods such as load lock facility, accurate determination of the flux, low background contamination, in-situ process monitoring tools, and heating, rotation and tilting of the substrate. Rutherford backscattering (RBS) shows that the films deposited without oxygen are stoichiometric, 50% oxygen and 50% Si, irrespective of the deposition rate or temperature. Such SiO films have a resistivity of ≥1013 Ω · and a nominal refractive index of 2 at 632.8 nm. The refractive index can be reduced by introducing a controlled amount of oxygen into the chamber to result in SiOx (x = 1–2) films. The SiO films have uniform density and composition, and are free from voids, or any inclusions of different crystalline or amorphous phases. These SiO films are easy to pattern and their erosion rate is slower than that of SiO2 deposited by plasma enhanced chemical vapor deposition (PECVD). During 192 h soak in 99°C deionized (DI) water, no moisture absorption was observed in SiO films deposited at a rate of 2 A/s. Even in films deposited at 11 A/s, the moisture content after 192 h soak in 99°C DI water was about one third the moisture content of an as-deposited typical PECVD SiO2 film, indicating that the SiO films are highly resistant to moisture absorption and the film quality improves with reducing deposition rate. The insulating, mechanical and optical properties of SiOx films make them suitable for many applications such as surface passivation, mask for processing and facet coating of lasers. The process can be easily integrated with MBE/CBE which would greatly simplify and improve the III–V semiconductor processing. It may also be possible to deposit such dielectric films by CBE using gaseous compound sources

A device quality of selective epitaxy growth of InGaAsP/InP multiple quantum well (MQW) structure using low-pressure metalorganic vapor phase epitaxy (MOVPE) technique is described. The technique is applied to a monolithically integrated electroabsorption modulator with distributed feedback (DFB) and distributed Bragg reflector (DBR) lasers. Superior device characteristics such as efficient modulation, low threshold current and high efficiency operation of the integrated devices are obtained.

Proximal metatarsal osteotomies are often performed in patients with hallux valgus and significant metatarsus primus varus. The crescentic osteotomy is popular; however, some authors have reported malunion of the metatarsal shaft caused by dorsal angulation of the osteotomy in a significant number of cases. Recently, proximal transverse “V” osteotomies have been reported to have good results, with rapid healing and no dorsal malunions.We compared the stability of a transverse, proximal “V” osteotomy, using two 0.062-inch K-wires or a 3.5-mm cortical screw for fixation, with that of the proximal crescentic osteotomy, using a 3.5-mm cortical screw fixation. The three osteotomy/fixation techniques were performed on 30 fresh-frozen cadaver feet. The specimens were loaded to failure at the fixation site by applying a load through the plantar surface of the first metatarsal head. Force versus displacement curves were obtained to calculate the failure load and stiffness. Statistical differences among the three groups were determined by the nonparametric Mann-Whitney U-test and the standard t-test.The “V” osteotomy/screw group was more stable than either the “V” osteotomy/pin group or the crescentic osteotomy/screw group. Differences in failure strength between the “V”/screw group and the other two groups were significant at the P < .01 level and the differences in stiffness were significant at the P = .05 level. No statistical differences were found between the “V”/pins and the crescentic/screw groups.

The authors fabricated YBCO thin films by RF magnetron sputter deposition onto ZrO/sub 2/, SrTiO/sub 3/, LaAlO/sub 3/, and MgO substrates and patterned these films into microbolometers. The influence of substrate type and device biasing current on the response of the microbolometers was measured. The responsivity and the speed of the devices were found to depend on the thermal conductivity of the substrates used. The fastest YBCO device was found on MgO, whereas the largest bolometric response was found on ZrO/sub 2/. It was found that the responsivity of a microbolometer increased with biasing current, but there was an optimal biasing current beyond which device performance deteriorated due to self heating. The results indicate that the most sensitive microbolometer requires a sharp YBCO resistivity transition, a low thermal conductivity substrate, and an optimal biasing current. >

Single-channel transmission at 320 Gb/s is demonstrated over record length of 200 km of nonzero-dispersion fiber. Typical terrestrial amplifier spacing of 100 km is achieved by using pseudolinear transmission and distributed Raman amplification. Stable semiconductor electroabsorption modulators are used in the transmitter, demultiplexer, and clock recovery, and uncorrelated multiplexing is employed in the OTDM transmitter.

An optoelectronic phase-locked loop (PLL) for clock recovery in high-speed optical time-division-multiplexed (OTDM) systems is proposed and experimentally demonstrated. The proposed scheme incorporates a pair of balanced photodetector through which the polarity ambiguity in error signal is resolved, and the cancellation of laser noise enables clock recovery with low timing jitter. Using an electroabsorption modulator as a phase detector, a 10-GHz clock signal with root-mean-square (rms) timing jitter of 300 fs is successfully extracted from 40 and 80 Gb/s return-to-zero (RZ) data stream. A 40- to 10-Gb/s demultiplexing is performed by using the recovered clock signal with no penalty introduced in the bit error rate performance.

Large diameter spiral wound modules enable significant reductions in reverse osmosis (RO) plant cost. A consortium of membrane manufacturers had identified sixteen inches as the optimum diameter for a new standard. In order to make full use of the cost saving potential of the large diameter, FilmTec's design considerations were based on a scale-up from the proven design of commercially available 8-inch modules. With the same materials and a leaf design as in 8-inch modules, the new 16-inch modules were built with a 4.3 times higher active membrane area and accordingly a 4.3 times higher permeate flow performance. The product water tube was designed for increased physical strength at even less permeate pressure drop. The endcaps feature interlocking technology without interconnectors and with internal brine seals for easier loading. The fiberglass shell was reinforced to resist axial compression arising from pressure drop and increased cross-section area. Sufficient safety margins were verified through extensive testing. A prototype tool for easy element loading and unloading was developed and applied to the demonstration plant at Bedok in Singapore. This plant is in operation since October 2007 to demonstrate equivalent performance of an 8-inch and a 16-inch RO system running side-by-side on a challenging waste water reuse application. Each system has three 7-element pressure vessels in a 2:1 arrangement and was operated at a constant flux of 17.3 lmh and a recovery of 75%. After some adjustments of the scaling inhibitor dosage the plant had come to a stable operation; at the time of this writing it was approaching 3 months without cleaning or rinsing. The normalized permeate flow of the 16-inch system was 4.3 times higher than the flow of the 8-inch system. A sustainable system flow performance at a fouling factor of 0.85 was demonstrated. The measured system salt rejection indicated an average module salt rejection of 99.65%.

YBCO thin films have been fabricated by single-target ion-beam deposition methods on MgO and LaAlO/sub 3/ substrates. The best T/sub c/ for YBCO on MgO substrates by the 900 degrees C ex-situ post-annealing process was found to be 80 K. It is believed that the presence of one or more nonsuperconducting phases in the conduction path led to the degradation of T/sub c/ values to levels below those expected for the bulk crystalline material. The best T/sub c/ for YBCO deposited on an LaAlO/sub 3/ substrate, by the in situ process with molecular oxygen and at a substrate temperature of 750 degrees C, was found to be 83 K. The best T/sub c/ using the atomic oxygen process was 80 K. The degradation of these T/sub c/ values below those of the bulk crystalline material is explained by the expansion of c-lattice parameters. The properties of these films were studied through microscopy, stoichiometry, X-ray diffraction, Auger analysis, and T/sub c/ measurements.

In this paper, the authors propose a new method for the propagation of uncertainty through non linear algorithms that may contain conditional statements. The approach is based on bittors, that are bit vectors where bits are expressed in terms of their probability to take value 1 or 0. Provided the logic operations between bittors are defined, the system of bittor numbers is introduced together with the fundamental operations. The bittor numbers can be processed with any algorithm provided the fundamental operations are redefined for bittors. This approach is suitable for multithread algorithms, thus conditional statements, can be handled easily. The implementation of bittor numbers and their operations in the Matlab environment is presented together with the numerical results of an example of application. The entropy as a measure of the information content of the bittor number is defined and proposed as a metric of loss of information content due to the elaboration. The authors discuss strengths, weaknesses and challenges of the approach and provide an overview of the potential benefits of this method.

The first autonomous rendezvous and docking in the history of the U.S. Space Program was successfully accomplished by Orbital Express (OE) in May of 2007, using the advanced video guidance sensor (AVGS) as the primary docking sensor. The United States now has a mature and flight proven sensor technology for supporting crew exploration vehicles (CEV) and commercial orbital transportation services (COTS) automated rendezvous and docking (AR&D).

An overview of virus structure is presented with an emphasis on icosahedral viruses, quasi-equivalence and functions of a virus capsid. Viruses are genetically economical entities because of the limited volume within the capsid that transports their genomes between susceptible cells. They construct these containers with multiple copies of one or a few gene products. These subunits contain the ‘program’ to assemble and in some cases mature in the appropriate environment with the proper stimulus. The strategy for creating large containers with multiple copies of a single gene product is geometrically straightforward, but requires remarkable molecular switching to achieve in practice. Virus structure research has contributed to the development of important antiviral drugs, vaccines and nanotechnology as well as being a paradigm for macromolecular assembly.

Nonenveloped viruses provide model systems for high-resolution structural study of whole virus capsids (and their components) and the principles of large-scale nucleoprotein tertiary and quaternary interactions. The structures of viruses ranging from 200 to 5000 A in diameter have now been determined at moderate to near atomic resolution, revealing a complicated array of architectures that conform to both predicted theories and show previously unobserved and completely unexpected types of associations. We organize a selection of these structures into various classifications based on their overall symmetry and size, and begin by examining common and uncommon coat protein folds, followed by detailed exploration of a few of the particles into which they assemble. Both past and present studies have found common features between viruses infecting different domains of life; yet a number of their structural features are not only unique among viruses, but all known protein structures.

Automation of functions in a data acquisition system adds more than just convenience in that accuracy can be enhanced through minimization of human errors. Several functions of the F.S.U. system using the IBM PC-AT computer are described including motion control via Alpha Products interface with sensing of target position by a potentiometric absolute encoder. Computer codes for control as well as multichannel spectral acquisition are also described.

An electroabsorption modulated laser (EML) is linearized by emulation and reversal of the nonlinear distortion using a companion EML inside an optoelectronic interferometer. Suppression of composite second-order and triple-beat signals to

A 21-year-old woman with a 5-cm secretory carcinoma of the breast was successfully treated by wide segmental excision, including removal of a portion of the nipple. At presentation, she had a 5-year history of predominantly yellow and occasionally bloody discharge from the nipple. The tumour had classical histological features of secretory carcinoma with surrounding hyaline fibrous tissue predominating, a feature previously associated with a good prognosis. Identification by frozen section of extension near the nipple led to intraoperative excision of a nipple segment. She is healthy with a satisfactory cosmetic result 14 years after excision and has breast fed two children from the affected breast.

In conclusion, we have demonstrated a simple means of suppressing SBS and multipath interference (MPI) when an electroabsorption modulated lasers (EML) is used as an optical transmitter for analog transmission at 1.55 /spl mu/m. This technique is essential to allow the high powers obtained with EDFAs to propagate with high CNR and low distortion.

Transmission performance of a 10-Gb/s integrated electroabsorption modulator/DFB laser has been evaluated in terms of the eye margin degradation and the receiver sensitivity penalty caused by the chromatic dispersion in the standard (non-DSF) fiber. Combination of low extinction ratio (/spl epsi/=5 dB) and negative chirp (/spl Delta/v=-0.01 nm) operation allows 10-Gb/s transmission over 130-km standard fiber without any dispersion penalty in receiver sensitivity (for 10/sup -9/ BER) and with a 7% eye margin for 10/sup -15/ BER.

AIM To determine the accuracy of multidetector row CT renal angiography in the preoperative evaluation of live kidney donors, and to identify potential pitfalls when reporting. METHODS Between July 1998 and June 2003, 74 consecutive live renal donors underwent contrast-enhanced multidetector row CT renal angiography before donor nephrectomy. The operative notes and radiological reports of all cases were reviewed retrospectively. Where a significant discrepancy was identified, the archived images were reviewed by two radiologists in the light of the intraoperative findings. RESULTS A total of 12 discrepancies were identified in 11 of the 74 cases (15%). In the preoperative CT angiography reports, 4 accessory arteries, 6 early-branching renal arteries, 1 duplicated renal vein and 1 accessory ureter were not identified; 9 of these were evident on review, but were not detected at the time of reporting. In 3 cases (1 accessory artery, the duplicated renal vein and the accessory ureter), the anomaly was not visible on review of the CT angiographic data, even with the benefit of hindsight. Surgical feedback during the study period resulted in modifications to CT technique and improved performance. CONCLUSION In the majority of cases, there was good correlation between preoperative CT renal angiography and operative findings. Most discrepancies were due either to an oversight by the reporting radiologist, or failure to fully appreciate the potential surgical significance of certain findings. Regular surgical feedback plays a valuable role in improving reporting accuracy and maintaining imaging standards.

We have demonstrated an electroabsorption-modulated hybrid integrated wavelength selectable laser source comprised of a spot-size converted 1.55 /spl mu/m DFB laser array and a spot-size converted semiconductor optical amplifier/EA modulator, mounted on silicon and optically connected via silica-on-silicon waveguides. The InP components are fabricated using a novel dual-waveguide spot-size converter integration technique that produces low coupling losses and uses existing manufacturing techniques. The low chirp performance of this device makes it suitable for long-haul transmission at 2.5 Gbit/s using any of 16 50 GHz spaced channels.

We demonstrate for the first time an EA-modulated hybrid integrated wavelength selectable laser comprised of 1.55 /spl mu/m DFB laser array and amplifier/modulator chips fabricated using a novel spot-size converter integration technique, and optically connected via silica-on-silicon waveguides. The device operates at 2.5 Gbit's over 16 50 GHz spaced channels with SMSR>33 dB, peak power from +1.6 to -6.2 dBm, and r.f. extinction ratio >0.39 dB for 2.6 V/sub p-p/ drive.

A series of studies is presented in which the overall goal of quantitative biomechanical assessment is to improve treatment. Included in the studies are descriptions of the biomechanical questions to be answered, instrumentation used to acquire the data and results of the clinical studies. The projects address the rehabilitative and post-surgical progress of children and adolescents with spastic cerebral palsy. A new motion analysis system designed to quantify foot and ankle kinematics is also presented. >