1,865 research outputs found
On the internal signature and minimal electric network realizations of reciprocal behaviors
In a recent paper, it was shown that (i) any reciprocal system with a proper
transfer function possesses a signature-symmetric realization in which each
state has either even or odd parity; and (ii) any reciprocal and passive
behavior can be realized as the driving-point behavior of an electric network
comprising resistors, inductors, capacitors and transformers. These results
extended classical results to include uncontrollable systems. In this paper, we
establish new lower bounds on the number of states with even parity
(capacitors) and odd parity (inductors) for reciprocal systems that need not be
controllable
On reciprocal systems and controllability
In this paper, we extend classical results on (i) signature symmetric
realizations, and (ii) signature symmetric and passive realizations, to systems
which need not be controllable. These results are motivated in part by the
existence of important electrical networks, such as the famous Bott-Duffin
networks, which possess signature symmetric and passive realizations that are
uncontrollable. In this regard, we provide necessary and sufficient algebraic
conditions for a behavior to be realized as the driving-point behavior of an
electrical network comprising resistors, inductors, capacitors and
transformers
On a concept of genericity for RLC networks
A recent definition of genericity for resistor-inductor-capacitor (RLC) networks is that the realisability set of the network has dimension one more than the number of elements in the network. We prove that such networks are minimal in the sense that it is not possible to realise a set of dimension n with fewer than n-1 elements. We provide an easily testable necessary and sufficient condition for genericity in terms of the derivative of the mapping from element values to impedance parameters, which is illustrated by several examples. We show that the number of resistors in a generic RLC network cannot exceed k+1 where k is the order of the impedance. With an example, we show that an impedance function of lower order than the number of reactive elements in the network need not imply that the network is non-generic. We prove that a network with a non-generic subnetwork is itself non-generic. Finally we show that any positive-real impedance can be realised by a generic network. In particular we show that sub-networks that are used in the important Bott-Duffin synthesis method are in fact generic.A. Morelli was supported by the MathWorks studentship - a Cambridge University Trust fund
Observations of X-rays and Thermal Dust Emission from the Supernova Remnant Kes 75
We present Spitzer Space Telescope and Chandra X-ray Observatory observations
of the composite Galactic supernova remnant Kes 75 (G29.7-0.3). We use the
detected flux at 24 microns and hot gas parameters from fitting spectra from
new, deep X-ray observations to constrain models of dust emission, obtaining a
dust-to-gas mass ratio M_dust/M_gas ~0.001. We find that a two-component
thermal model, nominally representing shocked swept-up interstellar or
circumstellar material and reverse-shocked ejecta, adequately fits the X-ray
spectrum, albeit with somewhat high implied densities for both components. We
surmise that this model implies a Wolf-Rayet progenitor for the remnant. We
also present infrared flux upper limits for the central pulsar wind nebula.Comment: 7 pages, 2 tables, 4 figures, uses emulateapj. Accepted for
publication in Ap
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Incidence, outcomes, and risk factors of pleural effusion in patients receiving dasatinib therapy for Philadelphia chromosome-positive leukemia.
Dasatinib, a second-generation BCR-ABL1 tyrosine kinase inhibitor, is approved for the treatment of chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia, both as first-line therapy and after imatinib intolerance or resistance. While generally well tolerated, dasatinib has been associated with a higher risk for pleural effusions. Frequency, risk factors, and outcomes associated with pleural effusion were assessed in two phase 3 trials (DASISION and 034/Dose-optimization) and a pooled population of 11 trials that evaluated patients with chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia treated with dasatinib (including DASISION and 034/Dose-optimization). In this largest assessment of patients across the dasatinib clinical trial program (N=2712), pleural effusion developed in 6-9% of patients at risk annually in DASISION, and in 5-15% of patients at risk annually in 034/Dose-optimization. With a minimum follow up of 5 and 7 years, drug-related pleural effusion occurred in 28% of patients in DASISION and in 33% of patients in 034/Dose-optimization, respectively. A significant risk factor identified for developing pleural effusion by a multivariate analysis was age. We found that overall responses to dasatinib, progression-free survival, and overall survival were similar in patients who developed pleural effusion and in patients who did not. clinicaltrials.gov identifier 00481247; 00123474
Applying Task Force Recommendations on Integrating Science and Practice in Health Service Psychology Education
The proper role of research skills and training to conduct research in professional psychology education has been controversial throughout the history of the field. An extensive effort was undertaken recently to address that issue and identify ways the field might move forward in a more unified manner. In 2015, the American Psychological Association (APA) Board of Educational Affairs convened a task force to address one of the recommendations made by the Health Service Psychology Education Collaborative in 2013. That recommendation stated that the education and training of health service psychologists (HSPs) include an integrative approach to science and practice that incorporates scientific-mindedness, training in research skills, and goes well beyond merely “consuming” research findings. The task force subsequently developed recommendations related to the centrality of science competencies for HSPs and how these competencies extend beyond training in evidence-based practice. This article discusses the findings of the task force and the implications of its recommendations for education and training in HSP. The challenges and opportunities associated with implementing these recommendations in HSP graduate programs are examined
Very Extended X-ray and H-alpha Emission in M82: Implications for the Superwind Phenomenon
We discuss the properties and implications of a 3.7x0.9 kpc region of
spatially-coincident X-ray and H-alpha emission about 11.6 kpc to the north of
the galaxy M82 previously discussed by Devine and Bally (1999). The PSPC X-ray
spectrum is fit by thermal plasma (kT=0.80+-0.17 keV) absorbed by only the
Galactic foreground column density. We evaluate the relationship of the
X-ray/H-alpha ridge to the M82 superwind. The main properties of the X-ray
emission can all be explained as being due to shock-heating driven as the
superwind encounters a massive ionized cloud in the halo of M82. This encounter
drives a slow shock into the cloud, which contributes to the excitation of the
observed H-alpha emission. At the same time, a fast bow-shock develops in the
superwind just upstream of the cloud, and this produces the observed X-ray
emission. This interpretation would imply that the superwind has an outflow
speed of roughly 800 km/s, consistent with indirect estimates based on its
general X-ray properties and the kinematics of the inner kpc-scale region of
H-alpha filaments. The gas in the M82 ridge is roughly two orders-of-magnitude
hotter than the minimum "escape temperature" at this radius, so this gas will
not be retained by M82.
(abridged)Comment: 24 pages (latex), 3 figures (2 gif files and one postscript),
accepted for publication in Part 1 of The Astrophysical Journa
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