Intrathecal Urokinase as a treatment for intraventricular hemorrhage in the preterm infant

Despite improvements in the care of preterm infants, intraventricular hemorrhage (IVH) and posthemorrhagic hydrocephalus (PHH) continue to be frequent occurrences in this patient population. Shunt procedures in these children are frequently complicated by obstruction and/or infection. As the hydrocephalus is usually caused by an obliterative arachnoiditis due to contact of the blood with the basilar meninges, it was postulated that infusion of urokinase into the ventricles of infants who have sustained an IVH would clear the blood, mitigate the arachnoiditis, and prevent the progression of PHH. Accordingly, 18 preterm infants who had sustained IVH and subsequently developed PHH were treated with intraventricular urokinase instilled via a surgically implanted subcutaneous reservoir. There were no complications associated with the urokinase. Infants were divided into two dosage groups: low dose (110,000–140,000 IU total) and high dose (280,000 IU total). One infant in the low-dose group died at 1 month of life of respiratory complications. In the low-dose group, 3 of 8 (37%) infants required shunt placement; in the high-dose group, all 9 required shunt placement. For the total group, the shunt rate was 71 %. This compares to a historical control group shunt rate of 92%. While the difference between the treatment group as a whole and control group approaches, but does not reach, statistical significance (p = 0.068), there was a significant reduction in the shunt rate when the low-dose group was considered separately (p \u3c 0.002). For those infants that required shunt placement, there were fewer shunt revisions performed in the treatment group than in the control group during the first 24 months following shunt placement: 0.67 versus 1.5 shunt revisions/shunted child. Initial experience with intraventricular urokinase following IVH and PHH in preterm infants suggests a beneficial effect in reducing the shunt revision rate in both high- and low-dose groups. Reduction in shunt placement rate is seen only in the low-dose group

Masses, radii, and orbits of small Kepler planets : The transition from gaseous to rocky planets

We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all of the transiting planets (41 of 42 have an FPP under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than three times the size of Earth. For 16 planets, the Doppler signal was securely detected, providing a direct measurement of the planet's mass. For the other 26 planets we provide either marginal mass measurements or upper limits to their masses and densities; in many cases we can rule out a rocky composition. We identify six planets with densities above 5 g cm-3, suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than 2 R ⊕. Larger planets evidently contain a larger fraction of low-density material (H, He, and H2O).Peer reviewedFinal Accepted Versio

ICAR: endoscopic skull‐base surgery

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Masses, radii, and orbits of small Kepler planets: the transition from gaseous to rocky planets

We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all of the transiting planets (41 of 42 have an FPP under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than three times the size of Earth. For 16 planets, the Doppler signal was securely detected, providing a direct measurement of the planet's mass. For the other 26 planets we provide either marginal mass measurements or upper limits to their masses and densities; in many cases we can rule out a rocky composition. We identify six planets with densities above 5 g cm-3, suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than 2 R ⊕. Larger planets evidently contain a larger fraction of low-density material (H, He, and H2O)

Review of Technologies for Current-Limiting Low-Voltage Circuit Breakers

Conventional air-magnetic circuit breakers, which are widely used in low-voltage applications, utilize magnetic forces that are produced by blowout coils, the geometry of the arcing contacts, or both. The magnetic forces act to push the are off the contacts into an are chute, which consists of a number of metal plates. The are chute causes the are to be split into a number of smaller arcs, thereby facilitating the process of extinguishing the are. In the last 20 years, the technology of circuit breakers has dramatically advanced, now including mature devices based on gas-blast (such as SF6) and vacuum interruption. at the same time, the technology of power electronic devices has evolved rapidly, leading to suggestions of a purely static circuit breaker based on solid-state electronic devices. Recently, several different proposals have appeared for current-limiting devices to be used in conjunction with or in replacement of conventional circuit breakers. The technologies involved in these proposals have ranged from very familiar (series reactors) to quite innovative (conductive polymer devices). Several of these proposed technologies have been used to a limited extent in commercial products, but they are very likely to see increasing applications as the technology matures. This paper begins with a short review of conventional circuit breaker action for background, then reviews the recent literature for current-limiting technologies that could be applied to low-voltage electric power systems. The paper concludes with a description of work underway for further development of conductive polymer current limiters