Urinalysis in clinical diagnosis

STUDY OBJECTIVE: To determine if the addition of alfentanil to propofol is more effective than propofol alone to provide adequate conditions for placement of a retrobulbar block prior to cataract surgery. DESIGN: Randomized, double-blinded study. SETTING: Outpatients at a university hospital. PATIENTS: 40 adult ASA physical status I, II, and III outpatients scheduled for elective cataract surgery. INTERVENTIONS: Patients were randomly assigned to receive one of four drug combinations prior to the placement of a retrobulbar block: Group 1, propofol alone; Group 2, alfentanil 5 micrograms/kg plus propofol; Group 3, alfentanil 10 micrograms/kg plus propofol; Group 4, alfentanil 15 micrograms/kg plus propofol. All patients were preoxygenated by face mask for two minutes prior to drug administration. The quality of conditions for block placement were determined by: (1) assessing the amount of movement by the patients while the block needle was in place, (2) cooperativeness of the patients during the operation, (3) hemodynamic side effects, (4) incidence and severity of respiratory depression, (5) incidence of nausea and vomiting, (6) recall of placement of the block, and (7) time to discharge from the hospital. Measurements and Main Results: The addition of alfentanil to propofol for sedation prior to placement of the retrobulbar block resulted in a dose-dependent reduction in movement by the patients. However, the highest dose of alfentanil (15 micrograms/kg) resulted in the greatest frequency (40% of the patients in this group) of respiratory depression (SpO2 < 90%). All patients were cooperative during the operation and responsive to verbal command within 5 minutes of placement of the block. In addition, all of the patients denied being nauseated, having vomited, or recalling block placement in the recovery room or the next day. CONCLUSIONS: The combination of alfentanil and propofol may be used to sedate patients in order to limit movement and provide a cooperative, alert patient with stable hemodynamics and limited respiratory depression during placement of retrobulbar block prior to ophthalmic surgery. However, excessive dosage of these drugs may result in hazardous respiratory depression in this patient population.     

Call control and traffic transport for connection-oriented highspeed wireless personal communications over metropolitan area networks

A distributed circuit-switched approach for supporting the deployment of high speed wireless personal communication services in urban areas through the interconnection of base stations via metropolitan area networks (MANs) is proposed. Broadband MANs minimize traffic congestion by dynamic sharing of link capacity and by serving as distributed switches for partitioning call control functions. While the DQDB protocol readily supports distributed packet-switching over the IEEE 802.6 MAN, isochronous traffic such as voice and video is best supported by circuit-switched connections. The authors present an enhanced bi-state pre-arbitrated (PA) transport mechanism, and associated call control and handoff management techniques, which enable distributed circuit-switching over the MAN. These capabilities are not currently addressed in the 802.6 standards. The bi-state PA transport mechanism facilitates statistical multiplexing of variable rate isochronous traffic sources. The network capacity is constrained by the call setup delay performance, and is analyzed by simulations. Alternative signaling architectures, involving different placements of call control network elements, are evaluated. The effects of erasure nodes, and close bus versus open bus architectures, are considered. The overlap inter-MAN call setup procedure is proposed to reduce delays. Different call handoff procedures are formulated according to the type of handoff and the resulting change in call connectivity. Most handoffs are intra-MAN, requiring simple procedures with short delays     

Role of Specimen Geometry in the Effect of Fiber Orientation on the Thermal Conductivity of a Uniaxial Carbon-Fiber-Reinforced Aluminoborosilicate Glass-Matrix Composite

A study concerning the effect of fiber orientation on the thermal conductivity of a uniaxial carbon-fiber-reinforced borosilicate glass was conducted. For thin specimens, and thick specimens with specimen sides cut parallel to the fiber direction, the dependence of thermal conductivity on fiber orientation showed excellent agreement with theoretical behavior predicted for a composite infinite in extent. In contrast, the thermal conductivity data for rectangular thick specimens fell well below the data for the thin and angled specimens. For fiber orientation of 45° and higher, at which the heat was directed toward the side of the specimen rather than across, the thermal conductivity values showed excellent agreement with theoretical behavior predicted for a finite composite strip with insulated sides.     

Assessing obesity: classification and epidemiology

Obesity is generally defined as a body mass index (BMI) of 30 kg/m2 and higher. Overweight is defined as a BMI between 25 and 30 kg/m2. The prevalence varies considerably between countries, and between regions within countries. It is estimated that more than half of adults aged 35-65 living in Europe are either overweight or obese. Overweight is more common among men than among women but obesity is more common among women. The prevalence of obesity in Europe is probably in the order of 10-20% in men and 15-25% in adult women. In most European countries who have reliable data on time-trends the prevalence of obesity seems to be increasing. In most European countries, obesity is usually inversely associated with socio-economic status, particularly among women. New classifications of overweight may be based on cut-off points for simple anthropometric measures which reflects both total adiposity as well as abdominal fatness.     

Inhibition of feline collateral vessel development following experimental thrombolic occlusion

We compared development of feline hindlimb collateral circulation after acute occlusion of the terminal aorta by ligation, thrombus formation, and formation of a "closed" aortic loop containing thromboplastin. Collateral circulation development was assessed by aortograms, scintillation scans, neurological signs following occlusion, measurement of hindlimb muscle blood flow, and forelimb and hindlimb temperature. In cats in which aortic occlusion was the result of ligation or thromboplastin in the aortic loop, paralysis was not evident. Aortograms and scintillation scans indicated hindlimb blood flow. Both muscle temperature and blood flow data indicated that the return of blood flow was rapid. The 5th lumbar artery appears to be the origin of the collateral vessels. The mid-zone component is a dorsal and ventral vertebral route and an epaxial muscle route. The reentry components are the 6th or 7th lumbar arteries. The collateral vessels arise from preexisting collateral vessels. Of those cats in which aortic occlusion was the result of a thrombus, all exhibited paralysis. Aortograms, scintillation scans, muscle temperature, and hindlimb blood flow data indicated reduced hindlimb blood flow. The results suggest that the thrombus has an inhibitory effect on the development of collateral circulation.     

Independently addressable VCSEL arrays on 3-μm pitch

We present an exceedingly dense linear vertical-cavity surface-emitting laser (VCSEL) array with independently addressable elements on a staggered 3-μm pitch. Our devices utilize an all-epitaxial structure and operate at a wavelength of 813 mm with threshold currents below 400 μA. The high-packing density is enabled by combining transparent contact technology with a planar laterally oxidized device architecture. The array exhibits low interelement thermal crosstalk and has electrical resistances of 3 MΩ between adjacent array elements