64,313 research outputs found
Antimisting kerosene
The antimisting additive ((FM-9) was tested in terms of its propulsion systems performance. The effect of the additive on engine operation was evaluated, operating problems were identified, the adaptability of engines to antimisting kerosene was assessed, and the potential viability of this fuel for use in present and future fan jet engines was determined
The use of AntiMisting Kerosene (AMK) in turbojet engines
The effect of antimisting kerosene (AMK) flow characteristics on fan jet engines and the impact of degradation requirements on the fuel system was evaluated. It was determined from the present program that AMK fuel cannot be used without predegradation, although some degradation occurs throughout the fuel feed system, expecially in the fuel pumps. There is a tendency toward FM-9 AMK additive agglomeration and gel formation when the liquid flows at a critical velocity through very small passages. The data indicate this phenomenon to be a function of the degree of degradation, the passage size, the differential pressure, the fluid temperature, and the accumulated flow time. Additionally, test results indicate that the long term cumulative effects of this phenomenon may require more degradation than the theoretical requirement determined from short term tests
Growth Patterns in the First Three Years of Life in Children with Classical Congenital Adrenal Hyperplasia Diagnosed by Newborn Screening and Treated with Low Doses of Hydrocortisone
Background: Linear growth is the best clinical parameter for monitoring metabolic control in classical congenital adrenal hyperplasia (CAH). Objective: To analyze growth patterns in children with CAH diagnosed by newborn screening and treated with relatively low doses of hydrocortisone during the first year of life. Patients and Methods: 51 patients (27 females) were diagnosed with classical CAH by newborn screening. All patients were treated with relatively low doses of hydrocortisone (9-15 mg/m(2) body surface area). 47 patients were additionally treated with fludrocortisone. Results: At birth, height SDS (H-SDS) was 1.1 +/- 1 in girls and 0.9 +/- 1.5 in boys. After 3 months, H-SDS decreased to 0.4 +/- 0.9 in girls and to 0.1 +/- 1.3 in boys. Over the 3-year period, H-SDS further decreased to -0.4 +/- 1.8 in girls and to -0.8 +/- 1 in boys and approached the genetic height potential (target H-SDS of girls -0.5 +/- 0.3 and target H-SDS of boys -0.9 +/- 0.7). During the first 9 months of age, growth velocity was slightly decreased in girls (18.2 +/- 1.9 cm) and boys (17.3 +/- 1.6 cm) when compared to a healthy reference population (girls 19.0 +/- 3.9 cm and boys 18.7 +/- 4.7 cm). At the age of 3 years, bone age was appropriate for chronological age in both girls (2.7 +/- 0.5 years) and boys (2.9 +/- 0.5 years). Conclusion: Birth length is above average in children with classical CAH, which might be the result of untreated hyperandrogenism in utero. With relatively low doses of hydrocortisone treatment, growth velocity decreases slightly during the first 9 months and H-SDS then approaches the genetic height potential. Copyright (C) 2010 S. Karger AG, Base
A distance limit for a class of model gamma-ray burst sources
Gamma ray burst sources are presumably not larger than 10 to the 9th power cm as inferred from observed flux variations. If they are homogeneous and isotropically radiating, then from photon density considerations, they would have to be optically thick due to gamma-gamma pair production when assumed to be too far away. Deviations of observed photo spectra from an exponential shape around 1 MeV lead to an upper limit of the possible distance of such sources of only 2 kpc from the sun. Thus the sources must be galactic unless the radiation is highly beamed or emerges from a relativistically moving shell. This conclusion depends only on observed parameters. The possible presence of particles and fields in the sources would require them to be even closer
Quick-disconnect coupling safe transfer of hazardous fluids
Quick-disconnect coupling is used for uncoupling of plumbing during ground-to-vehicle transfer of cryogenic and hazardous fluids. The coupling allows remote positive control of liquid pressure and flow during the transfer operation, remote connection and separation capabilities, and negligible liquid spillage upon disconnection
A near deterministic linear optical CNOT gate
We show how to construct a near deterministic CNOT using several single
photons sources, linear optics, photon number resolving quantum non-demolition
detectors and feed-forward. This gate does not require the use of massively
entangled states common to other implementations and is very efficient on
resources with only one ancilla photon required. The key element of this gate
are non-demolition detectors that use a weak cross-Kerr nonlinearity effect to
conditionally generate a phase shift on a coherent probe, if a photon is
present in the signal mode. These potential phase shifts can then be measured
using highly efficient homodyne detection.Comment: 4 pages, 3 figure
Luminosity segregation in galaxy clusters as an indication of dynamical evolution
Theoretical models describing the dynamical evolution of self-gravitating systems predict a spatial mass segregation for more evolved systems, with the more massive objects concentrated toward the center of the configuration. From the observational point of view, however, the existence of mass segregation in galaxy clusters seems to be a matter of controversy. A special problem in this connection is the formation of cD galaxies in the centers of galaxy clusters. The most promising scenarios of their formation are galaxy cannibalism (merger scenario) and growing by cooling flows. It seems to be plausible to consider the swallowing of smaller systems by a dominant galaxy as an important process in the evolution of a cD galaxy. The stage of the evolution of the dominant galaxy should be reflected by the surrounding galaxy population, especially by possible mass segregation effects. Assuming that mass segregation is tantamount to luminosity segregation we analyzed luminosity segregation in roughly 40 cD galaxy clusters. Obviously there are three different groups of clusters: (1) clusters with luminosity segregation, (2) clusters without luminosity segregation, and (3) such objects exhibiting a phenomenon which we call antisegregation in luminosity, i.e. a deficiency of bright galaxies in the central regions of clusters. This result is interpreted in the sense of different degrees of mass segregation and as an indication for different evolution stages of these clusters. The clusters are arranged in the three segregation classes 2, 1, and 0 (S2 = strong mass segregation, S1 = moderate mass segregation, S0 = weak or absent mass segregation). We assume that a galaxy cluster starts its dynamical evolution after virialization without any radial mass segregation. Energy exchange during encounters of cluster members as well as merger processes between cluster galaxies lead to an increasing radial mass segregation in the cluster (S1). If a certain degree of segregation (S2) has been established, an essential number of slow-moving and relative massive cluster members in the center will be cannibalized by the initial brightest cluster galaxy. This process should lead to the growing of the predominate galaxy, which is accompanied by a diminution of the mass segregation (transition to S1 and S0, respectively) in the neighborhood of the central very massive galaxy. An increase of the areal density of brighter galaxies towards the outer cluster regions (antisegregation of luminosity), i.e. an extreme low degree of mass segregation was estimated for a substantial percentage of cD clusters. This result favors the cannibalism scenario for the formation of cD galaxies
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