1,935 research outputs found
The use of satellites in non-goestationary orbits for unloading geostationary communication satellite traffic peaks. Volume 2: Technical report
The part of the geostationary (GEO) orbital arc used for United States domestic fixed, communications service is rapidly becoming filled with satellites. One of the factors currently limiting its utilization is that communications satellites must be designed to have sufficient capacity to handle peak traffic leads, and thus are under utilized most of the time. A solution is to use satellites in suitable non-geostationary orbits to unload the traffic peaks. Three different designs for a non-geostationary orbit communications satellite system are presented for the 1995 time frame. The economic performance is analyzed and compared with geostationary satellites for two classes of service, trunking and customer premise service. The result is that the larger payload of the non-geostationary satellite offsets the burdens of increased complexity and worse radiation environment to give improved economic performance. Depending on ground terminal configuration, the improved economic performance of the space segment may be offset by increased ground terminal expenses
Comparative Effectiveness of Step-up Therapies in Children with Asthma Prescribed Inhaled Corticosteroids : A Historical Cohort Study
This work was supported by the Respiratory Effectiveness Group. Acknowledgments We thank the Respiratory Effectiveness Group for funding this work, Annie Burden for assistance with statistics, and Simon Van Rysewyk and Lisa Law for assistance with medical writing.Peer reviewedPostprin
Crystal Structure and Twisted Aggregates of Oxcarbazepine Form III
Polymorphism and crystal habit play vital roles in dictating the properties of crystalline materials. Here, the structure and properties of oxcarbazepine (OXCBZ) form III are reported along with the occurrence of twisted crystalline aggregates of this metastable polymorph. OXCBZ III can be produced by crystallization from the vapor phase and by recrystallization from solution. The crystallization process used to obtain OXCBZ III is found to affect the pitch, with the most prominent effect observed from the sublimation-grown OXCBZ III material where the pitch increases as the length of aggregates increases. Sublimation-grown OXCBZ III follows an unconventional mechanism of formation with condensed droplet formation and coalescence preceding nucleation and growth of aggregates. A crystal structure determination of OXCBZ III from powder X-ray diffraction methods, assisted by crystal structure prediction (CSP), reveals that OXCBZ III, similar to carbamazepine form II, contains void channels in its structure with the channels, aligned along the c crystallographic axis, oriented parallel to the twist axis of the aggregates. The likely role of structural misalignment at the lattice or nanoscale is explored by considering the role of molecular and closely related structural impurities informed by crystal structure prediction
New Galaxies Discovered in the First Blind HI Survey of the Centaurus A Group
We have commenced a 21-cm survey of the entire southern sky (\delta < 0
degrees, -1200 km/s < v < 12700 km/s) which is ''blind'', i.e. unbiased by
previous optical information. In the present paper we report on the results of
a pilot project which is based on data from this all-sky survey. The project
was carried out on an area of 600 square degrees centred on the nearby
Centaurus A (Cen A) group of galaxies at a mean velocity of v ~ 500 km/s. This
was recently the subject of a separate and thorough optical survey.
We found 10 new group members to add to the 21 galaxies already known in the
Cen A group: five of these are previously uncatalogued galaxies, while five
were previously catalogued but not known to be associated with the group.
We found optical counterparts for all the HI detections, most of them
intrinsically very faint low surface brightness dwarfs. The new group members
add approximately 6% to the HI mass of the group and 4% to its light. The HI
mass function, derived from all the known group galaxies in the interval 10^7
\Msun of HI to 10^9 \Msun of HI, has a faint-end slope of 1.30 +/- 0.15,
allowing us to rule out a slope of 1.7 at 95% confidence. Even if the number in
the lowest mass bin is increased by 50%, the slope only increases to 1.45 +/-
0.15.Comment: 19 pages Latex, 6 figures (Fig. 2 in four parts, Fig.5 in two parts).
To appear in The Astrophysical Journal (Vol. 524, October 1999
‘Video Replay: Families, films and fantasy’ as a transformational text: Commentary on Valerie Walkerdine's ‘Video Replay’.
In this commentary I explore the significance of Valerie Walkerdine's paper ‘Video Replay: Families, Films and Fantasy’. I review its impact in 1986 and then discuss how some of its ideas about subjectivity and popular culture – specifically film - can be developed in the contemporary context. A recurring fantasy of Rocky II and its reception is that of social and psychological transformation. I address this theme by drawing on the work of Christopher Bollas to argue that Walkerdine's psychosocial analysis continues to facilitate, across a range of contexts, some of the transformational processes described in her article
Treatment guided by fractional exhaled nitric oxide in addition to standard care in 6- to 15-year-olds with asthma : the RAACENO RCT
Funding This project was funded by the Efficacy and Mechanism Evaluation (EME) programme, a MRC and National Institute for Health and Care Research (NIHR) partnership. This will be published in full in Efficacy and Mechanism Evaluation; Vol. 9, No. 4. See the NIHR Journals Library website for further project information.Peer reviewedPublisher PD
Crystal structure and twisted aggregates of oxcarbazepine form III
Polymorphism and crystal habit play vital roles in dictating the properties of crystalline materials. Here, the structure and properties of oxcarbazepine (OXCBZ) form III are reported along with the occurrence of twisted crystalline aggregates of this metastable polymorph. OXCBZ III can be produced by crystallization from the vapor phase and by recrystallization from solution. The crystallization process used to obtain OXCBZ III is found to affect the pitch, with the most prominent effect observed from the sublimation-grown OXCBZ III material where the pitch increases as the length of aggregates increases. Sublimation-grown OXCBZ III follows an unconventional mechanism of formation with condensed droplet formation and coalescence preceding nucleation and growth of aggregates. A crystal structure determination of OXCBZ III from powder X-ray diffraction methods, assisted by crystal structure prediction (CSP), reveals that OXCBZ III, similar to carbamazepine form II, contains void channels in its structure with the channels, aligned along the c crystallographic axis, oriented parallel to the twist axis of the aggregates. The likely role of structural misalignment at the lattice or nanoscale is explored by considering the role of molecular and closely related structural impurities informed by crystal structure prediction
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