13,102 research outputs found
Optical Design and Active Optics Methods in Astronomy
Optical designs for astronomy involve implementation of active optics and
adaptive optics from X-ray to the infrared. Developments and results of active
optics methods for telescopes, spectrographs and coronagraph planet finders are
presented. The high accuracy and remarkable smoothness of surfaces generated by
active optics methods also allow elaborating new optical design types with high
aspheric and/or non-axisymmetric surfaces. Depending on the goal and
performance requested for a deformable optical surface analytical
investigations are carried out with one of the various facets of elasticity
theory: small deformation thin plate theory, large deformation thin plate
theory, shallow spherical shell theory, weakly conical shell theory. The
resulting thickness distribution and associated bending force boundaries can be
refined further with finite element analysis. Keywords: active optics, optical
design, elasticity theory, astronomical optics, diffractive optics, X-ray
optic
Counseling Parents of Retarded Children
Editor\u27s Note: The material that follows was prepared simultaneously with that contained in the article, On Mentally Retarded Children and we feel it is repetitious only in ifs emphasis of the subject matter and its\u27 vital concern in today\u27s pattern of living. The Reading Guides should be of particular interest and a source of assistance to parents seeking advice and counsel
Full Service ISDN Satellite (FSIS) network model for advanced ISDN satellite design and experiments
The Full Service Integrated Services Digital Network (FSIS) network model for advanced satellite designs describes a model suitable for discrete event simulations. A top down model design uses the Advanced Communications Technology Satellite (ACTS) as its basis. The ACTS and the Interim Service ISDN Satellite (ISIS) perform ISDN protocol analyses and switching decisions in the terrestrial domain, whereas FSIS makes all its analyses and decisions on-board the ISDN satellite
Scenarios and performance measures for advanced ISDN satellite design and experiments
Described here are the contemplated input and expected output for the Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) and Full Service ISDN Satellite (FSIS) Models. The discrete event simulations of these models are presented with specific scenarios that stress ISDN satellite parameters. Performance measure criteria are presented for evaluating the advanced ISDN communication satellite designs of the NASA Satellite Communications Research (SCAR) Program
What is Strategic Competence and Does it Matter? Exposition of the Concept and a Research Agenda
Drawing on a range of theoretical and empirical insights from strategic management and the cognitive and organizational sciences, we argue that strategic competence constitutes the ability of organizations and the individuals who operate within them to work within their cognitive limitations in such a way that they are able to maintain an appropriate level of responsiveness to the contingencies confronting them. Using the language of the resource based view of the firm, we argue that this meta-level competence represents a confluence of individual and organizational characteristics, suitably configured to enable the detection of those weak signals indicative of the need for change and to act accordingly, thereby minimising the dangers of cognitive bias and cognitive inertia. In an era of unprecedented informational burdens and instability, we argue that this competence is central to the longer-term survival and well being of the organization. We conclude with a consideration of the major scientific challenges that lie ahead, if the ideas contained within this paper are to be validated
Finite Conductivity in Mesoscopic Hall Bars of Inverted InAs/GaSb Quantum Wells
We have studied experimentally the low temperature conductivity of mesoscopic
size InAs/GaSb quantum well Hall bar devices in the inverted regime. Using a
pair of electrostatic gates we were able to move the Fermi level into the
electron-hole hybridization state, and observe a mini gap. Temperature
dependence of the conductivity in the gap shows residual conductivity, which
can be consistently explained by the contributions from the free as well as the
hybridized carriers in the presence of impurity scattering, as proposed by
Naveh and Laikhtman [Euro. Phys. Lett., 55, 545-551 (2001)]. Experimental
implications for the stability of proposed helical edge states will be
discussed.Comment: 5 pages, 4 figure
Overview of bladder heating technology: matching capabilities with clinical requirements.
Moderate temperature hyperthermia (40-45°C for 1 h) is emerging as an effective treatment to enhance best available chemotherapy strategies for bladder cancer. A rapidly increasing number of clinical trials have investigated the feasibility and efficacy of treating bladder cancer with combined intravesical chemotherapy and moderate temperature hyperthermia. To date, most studies have concerned treatment of non-muscle-invasive bladder cancer (NMIBC) limited to the interior wall of the bladder. Following the promising results of initial clinical trials, investigators are now considering protocols for treatment of muscle-invasive bladder cancer (MIBC). This paper provides a brief overview of the devices and techniques used for heating bladder cancer. Systems are described for thermal conduction heating of the bladder wall via circulation of hot fluid, intravesical microwave antenna heating, capacitively coupled radio-frequency current heating, and radiofrequency phased array deep regional heating of the pelvis. Relative heating characteristics of the available technologies are compared based on published feasibility studies, and the systems correlated with clinical requirements for effective treatment of MIBC and NMIBC
Interim Service ISDN Satellite (ISIS) network model for advanced satellite designs and experiments
The Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) Network Model for Advanced Satellite Designs and Experiments describes a model suitable for discrete event simulations. A top-down model design uses the Advanced Communications Technology Satellite (ACTS) as its basis. The ISDN modeling abstractions are added to permit the determination and performance for the NASA Satellite Communications Research (SCAR) Program
Anomalous enhancement of a penguin hadronic matrix element in B->K eta'
We estimate the density matrix element for the pi^0, eta and eta' production
from the vacuum in the large-N_c limit. As a consequence, we find that the QCD
axial anomaly leads to highly non-trivial corrections to the usual flavour
SU(3) relations between B^0-> K^0 pi^0, B^0-> K^0 eta and B^0-> K^0 eta' decay
amplitudes. These corrections may explain why the B-> K eta' branching ratio is
about six times larger than the B-> K pi one.Comment: 5 pages, 1 figur
- …