Let Tndenote the length of the shortest closed path connecting n random points uniformly distributed over the unit square. We prove that for some number K, we have, for all t ≥ 0, P(|Tn- E(Tn)| ≥ t) ...≤ K exp(-t2/K).
Osteoporotic burst fractures with neurologic symptoms are typically treated with neural decompression and multilevel instrumented fusion. These large surgical interventions are challenging because of ...patients' advanced ages, medical co-morbidities, and poor fixation secondary to osteoporosis. The purpose of this retrospective clinical study was to describe a novel technique for the treatment of osteoporotic burst fractures and symptomatic spinal stenosis via a limited thoracolumbar decompression with open cement augmentation vertebroplasty (VP) or kyphoplasty (KP). Indications for decompression and cement augmentation were intractable pain at the level of a known osteoporotic burst fracture with symptoms of spinal stenosis. As such, 25 patients (mean age, 76.1 years) with low-energy, osteoporotic, thoracolumbar burst fractures (7 males, 18 females; 39 fractures) were included. In all cases, laminectomy of the stenotic level(s) was followed by vertebral cement augmentation (9 VP; 16 KP). When a spondylolisthesis at the decompressed level was present, instrumentation was applied across the listhetic level (n = 9). Clinical outcome (1 = poor to 4 = excellent) was assessed on last clinical follow-up (mean, 44.8 wks). In addition, a modified MacNab's grading criteria was used to objectively assess patient outcomes postoperatively. Radiographic analysis of sagittal contour was assessed preoperatively, immediately postoperatively, and at final follow-up. The average time from onset of symptoms to intervention was 19 weeks (range, 0.3-94 wks). A mean of 1.6 fractures/patient was augmented (range, 1-3 fractures) and 2.8 levels were decompressed (range, 1-6 levels). No statistical difference in anatomic distribution or number of fractures between the VP and KP groups or in the instrumented versus noninstrumented patients was noted (P > 0.05). An overall subjective outcome score of 3.4 was noted. Twenty of 25 patients were graded as excellent/good according to the modified MacNab's criteria. The choice of augmentation procedure or use of instrumentation did not predict outcome (P = 0.08). Overall, 1.7 degrees of sagittal correction was obtained at final follow-up. One patient was noted to have progressive kyphosis after KP. The use of a limited-posterior decompression and open cement augmentation via VP or KP is a safe treatment option for patients who have osteoporotic burst fractures and who are incapacitated from fracture pain and concomitant stenosis. After thoracolumbar decompression, open VP/KP provides direct visualization of the posterior vertebral body wall, allowing for safe cement augmentation of burst fractures, stabilizing the spine, and obviating the need for extensive spinal reconstruction. Although clinically successful, this technique warrants careful patient selection.
Transmission lines of very low characteristic impedance (Z/sub 0/) are fabricated and analyzed. The transmission lines are fabricated on the benzo-cyclo-butene (BCB) films of a low dielectric ...constant. Two types of coplanar waveguide (CPW) structures are fabricated, which include bottom-ground and double-ground type. Measurement shows that Z/sub 0/ values for each CPW type are 7.3 and 9.4 /spl Omega/, respectively, at a signal line width of 100 /spl mu/m. When the ratio between the spacing of bottom-ground and the signal line width becomes greater than 2.5, the Z/sub 0/ is nearly saturated. In addition, thin film microstrip lines fabricated using the BCB insertion layers show very low Z/sub 0/ of 25.5 /spl Omega/, and this impedance is /spl sim/64 % of the values obtained from the BCB-based CPW structures of the same line width.
A large meningioma in the cerebellopontine angle manifested itself as a contralateral hemifacial spasm. On computed tomographic and magnetic resonance imaging scans, the brain stem was markedly ...displaced and distorted by the tumor. After total removal of the meningioma, the hemifacial spasm completely disappeared.
To evaluate the performance of portal venous puncture with use of magnetic resonance (MR) guidance, and to place a transjugular intrahepatic portosystemic shunt (TIPS) in a swine model.
A study of 12 ...swine was performed to evaluate the ability of interventional MR imaging to guide portal vein puncture and TIPS placement. Six swine had catheters placed in the right hepatic vein under C-arm fluoroscopy. A nitinol guide wire was left in the vein and the animals were then moved into an open configuration MR imaging unit. A TIPS needle set was used to puncture the portal vein using MR fluoroscopy. The animals were transferred to the C-arm, and venography confirmed portal vein puncture. A follow-up study was performed in six additional swine to place a TIPS using only MR imaging guidance. MR tracking was used to advance a catheter from the right atrium into the inferior vena cava. Puncture of the portal vein was performed and a nitinol stent was placed, bridging the hepatic parenchyma. MR venogram confirmed placement.
Successful portal vein puncture was achieved in all animals. The number of punctures required decreased from 12 in the first animal to a single puncture in the last eight swine. A stent was successfully placed across the hepatic tract in all six swine.
Real-time MR imaging proved to be a feasible method to guide portal vein puncture and TIPS placement in pigs.
The general pharmacological properties of 2-amino-9-(3-acetoxymethyl-4-isopropoxycarbonyloxybut-1-yl)purine (CAS 247081-81-8, SK 1899), a new potential antiviral agent, were investigated in mice, ...rats, guinea pigs, rabbits, and dogs. The oral administration of 50, 150, and 500 mg/kg of SK 1899 had no effects on the central nervous system except that it slightly increased the spontaneous locomotor activity in mice at a dose of 500 mg/kg. SK 1899 did not disturb either the spontaneous motility or contractor-induced contraction of the isolated organs such as guinea pig ileum, rat uterus, guinea pig vas deferens, and guinea pig trachea at concentrations up to 10(-4) mol/l. It slightly increased the contractile force in the isolated guinea pig atrium at a concentration of 10(-4) mol/l. Following intravenous infusion of 5, 15, and 50 mg/kg of SK 1899 to anesthetized dogs, it did not change the mean arterial pressure, heart rate, left ventricular systolic pressure (LVSP), and respiratory rate, while it slightly increased the left ventricular positive dP/dtmax (LV + dP/dtmax) at a dose of 50 mg/kg. SK 1899 did not induce any significant changes in the intestinal charcoal meal transit in mice, basal gastric juice secretion in rats, and renal function in rats. It did not affect the blood coagulation system and phenolsulfonphthalein secretion in rats. These findings suggest that SK 1899 has a very low potential to induce any adverse pharmacological effects at the doses showing antiviral activity.
An intensive measurement campaign was performed in June 2000 at the Mt. Cimone station (44°11' N -- 10°42' E, 2165 m asl, the highest mountain in the northern Italian Apennines) to study ...photochemical ozone production in the lower free troposphere. In general, average mixing ratios of important trace gases were not very high (121 ± 20 ppbv CO, 0.284 ± 0.220 ppbv NOx, 1.15 ± 0.8 ppbv NOy, 58 ± 9 ppbv O3), which indicates a small contribution by local pollution. This is supported by the analysis of volatile organic compounds (VOCs), that exhibit mean levels typical for background continental air (e.g. 905 ± 200\,pptv C2H6 268 ± 110\,pptv C3H8, 201 ±102 pptv C2H2, 111 ± 124 pptv isoprene, 65 ± 33 pptv benzene). Furthermore, significant diurnal variations for a number of trace gases (O3, CO, NOx, NOy, HCHO) indicate the presence of free tropospheric airmasses at nighttime as a consequence of local catabatic winds. Average mid-day peroxy radical concentrations at Mt. Cimone are of the order of 30 pptv. At mean NO concentrations of the order of 40 pptv this gives rise to significant in situ net O3 production of 0.1--0.3 ppbv/hr. The importance of O3 production is supported by correlations between O3, CO, NOz, and HCHO, and between HCHO, CO and NOy.
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