A next-generation optical regional access network

We describe an optical regional access network which combines electronic IP routing with intelligent networking functionality of the optical WDM layer. The optical WDM layer provides such networking functions as network logical topology reconfiguration, optical flow switching to offload traffic and bypass IP routers, wavelength routing of signals, protection switching and restoration in the optical domain, and flexible network service provisioning by reconfigurable wavelength connectivity. We discuss key enabling technologies for the WDM layer and describe their limitations. The symbiosis of electronic and optical WDM networking functions also allows support for heterogeneous format traffic and will enable efficient gigabit-per-second user access in next-generation Internet networks     

Five channel WDM soliton pulse generation using sinusoidally drivenelectroabsorption modulators in 16×1 laser/modulator array

Five wavelength multiplexed pulse streams are generated in an integrated 16×1 laser modulator array by sinusoidally driving five of the potential 16 electroabsorption modulators. At a repetition rate of 2.5 GHz, near transform-limited pulses spaced in wavelength over 7.6 nm are observed. Pseudorandom coding of one channel is achieved by applying an electrical RZ data signal to the modulator     

Efficient Drive Cycle Simulation

Drive cycle simulations of longitudinal vehicle models are important aids for the design and analysis of power trains, and tools currently on the market mainly use two different methods for such simulations: the forward dynamic and quasi-static inverse simulations. Here, a known theory for the stable inversion of nonlinear systems is used to combine the fast simulation times of the quasi-static inverse simulation with the ability of the forward dynamic simulation to include transient dynamics. The stable inversion technique and a new implicit driver model together form a new concept: inverse dynamic simulation. This technique is demonstrated to be feasible for vehicle propulsion simulation and specifically for three power train applications that include important dynamics that cannot be handled using quasi-static inverse simulation. The extensions are engine dynamics, driveline dynamics, and gas flow dynamics for diesel engines, which are also selected to represent important properties, such as zero dynamics, resonances, and nonminimum-phase systems. It is shown that inverse dynamic simulation is easy to set up, gives short simulation times, and gives consistent results for design space exploration. This makes inverse dynamic simulation a suitable method to use for drive cycle simulation, particularly in situations requiring many simulations, such as optimization over design space, power train configuration optimization, or the development of power train control strategies.     

Pseudohypoaldosteronism due to sweat gland dysfunction

Pseudohypoaldosteronism is an uncommon disorder characterized by urinary sodium wasting and is attributed to a defect in distal renal tubular sodium handling with failure to respond to endogenous aldosterone. Sweat electrolyte values in other reported patients, when measured, have been normal. A 3.5-year-old girl developed repeated episodes of dehydration, hyponatremia, and hyperkalemia during the first 19 months of life. Serum sodium was as low as 113 mEq/liter and potassium as high as 11.1 mEq/liter. Her plasma and urinary aldosterone levels were persistently elevated (Figs. 1-4). Unlike patients with classic pseudohypoaldosteronism she demonstrated no urinary sodium wasting (Figs. 2 and 3). During episodes of hyponatremia and reduced sodium intake her urinary sodium was less than 5 mEq/liter. In addition, her sweat sodium concentration was consistently above 125 mEq/liter and salivary sodium concentration above 58 mEq/liter. Her chest x-ray, 72-hr fecal fat excretion, serum and urinary pancreatic amylase (amy-2) were normal, providing no evidence for cystic fibrosis. It is proposed that this patient represents a new variant of pseudohypoaldosteronism with excessive loss of sodium from the sweat and salivary glands instead of the kidneys.     

Fatal disseminated intravascular coagulation after autologous islet transplantation

Autologous islet transplantation after pancreatectomy has been used in the surgical management of patients with intractable pain secondary to chronic pancreatitis. Total or near total pancreatectomy invariably leads to exogenous insulin dependence in these patients unless they undergo islet transplantation. Transplantation of autologous islet cells harvested from the patient's pancreas into the liver through portal vein infusion has led to long-term euglycemia in 30% to 50% of patients. We report the development of disseminated intravascular coagulation and fatal hemorrhagic shock in a 36-year-old woman after total pancreatectomy and autologous islet transplantation through retrograde infusion into the splenic vein. We report the clinical and pathological findings and discuss the possible pathophysiological mechanisms involved in the development of disseminated intravascular coagulation after this procedure.     

Cartilaginous tumors of the larynx. A report of two cases with definitive diagnosis by fine needle aspiration and computed tomography

BACKGROUND: Cartilaginous tumors of the larynx are rate tumors with an indolent course. In the past they were diagnosed by radiographic or computed tomographic imaging and laryngoscopic or surgical biopsy. The literature contains few examples of fine needle aspiration biopsy of these tumors. CASES: Smears of the fine needle aspirates from two cases of cartilaginous tumors of the larynx consisted of a mucinous background containing chondroid fragments of benign-appearing lacunar cells. Cytomorphologic and architectural features of smears and cell block preparations correlated well with histologic sections for subsequent surgical specimens. Both tumors were classified by cytology and histology as low grade cartilaginous tumors. CONCLUSION: Fine needle aspiration biopsy, together with typical computed tomographic images, is adequate for diagnosis, cost-effective and safe and can be performed in an outpatient setting.     

Power penalty for optical signals due to dispersion slope in WDMfilter cascades

We calculate the receiver power penalty due to the accumulated dispersion slope of optical filter cascades in wavelength-division-multiplexed optical networks. For flat-top fiber Bragg grating and thin-film filters, dispersive rather than amplitude filter effects dominate the cascade power penalty, which increases with dispersion slope and signal frequency detuning from the cascade zero-dispersion point. The dispersion slope of these filters varies as the inverse cube of their bandwidth, using increased penalties for narrow filters in systems with small channel spacing, For a 60-GHz-wide Bragg grating filter with a 1.3-ns/nm² dispersion slope, a cascade of 26 filters can be tolerated at 10 Gbit/s with ±5 GHz allowed detuning. Optically preamplified receivers have significantly larger dispersion penalties than thermal-noise-limited receivers     

Demonstration of clonality in neutrophils using FISH in a case of chronic neutrophilic leukemia

This study was designed to elucidate the role of the adventitia in NO-mediated vascular effects of lipopolysaccharide (LPS). After incubation of rat aorta with LPS, the adventitia generated 3.5 times more nitrite plus nitrate than a corresponding segment of media. Control media covered by adventitia from LPS-treated aortic rings exhibited a 4 fold elevated level of cyclic GMP. Medial layers from LPS-treated aortic rings (like LPS-treated adventitia-intact rings) exhibited a decrease in sensitivity to noradrenaline (NA) that was reversed by 1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one (1 microM) or N omega-nitro-L-arginine methylester (0.3 mM). However, in contrast to LPS-treated adventitia-intact rings, medial layers showed no reduction in maximal contraction to NA and virtually no relaxation to L-arginine. These data indicate that in blood vessels exposed to LPS, the adventitia is a more powerful source of NO than the media. The adventitia-derived NO can reach soluble guanylyl cyclase in the medial layer and contribute greatly to vascular hyporeactivity and L-arginine-induced relaxation observed in blood vessels exposed to LPS.     

The NGI ONRAMP test bed: reconfigurable WDM technology for nextgeneration regional access networks

Next generation internet optical network for regional access using multi-wavelength protocols (NGI ONRAMP) is a pre-competitive consortium sponsored by DARPA. Its mission is to develop architectures, protocols, and algorithms for wavelength division multiplexing (WDM)-based regional access networks that will effectively support the NGI. A reconfigurable WDM test bed is being built to demonstrate some of the key thrusts of the consortium, including dynamic service provisioning and optical flow switching, service protection in the optical domain, medium access control protocols, and network control and management geared for the efficient transport of Internet traffic over WDM networks. The ONRAMP test bed will consist of a feeder network connecting via access nodes to distribution networks on which the end users reside. ONRAMP network reconfiguration is enabled by access nodes that contain both optical and electronic switching components, allowing data traffic to be routed all-optically through the network or to be switched and aggregated by electronic Internet protocol (IP) routers. This paper describes the goals and basic architecture of the ONRAMP test bed, as well as the design, construction, and characterization of the network access nodes. To illustrate test bed operation, we demonstrate optical flow switching over the test bed that achieves Gb/s throughput of TCP data between end user workstations     

A 2.5-Gbit/s return-to-zero integrated DBR laser/modulatortransmitter

We demonstrate a novel modulation scheme in which both data-encoding and pulse generation are achieved using a single, wavelength tunable, integrated semiconductor laser/modulator. Data-encoded, near-transform limited 66 ps pulses are obtained at 2.5 Gbit/s and BER performance is reported