3,106 research outputs found
Phenomenological theory of cuprate superconductivity
Reasonably good agreement with the superconducting transitiontemperatures of the cuprate highâT c superconductors can be obtained on the basis of an approximate phenomenological theory. In this theory, two criteria are used to calculate the superconducting transitiontemperature. One is that the quantum wavelength is of the order of the electronâpair spacing. The other is that a fraction of the normal carriers exist as Cooper pairs at T c . The resulting simple equation for T c contains only two parameters: the normal carrier density and effective mass. We calculate specific transition temperatures for 12 cuprate superconductors
Head and Neck Manifestations of Eosinophilic Granulomatosis with Polyangiitis: A Systematic Review.
OBJECTIVE: To conduct the first and only systematic review of the existing literature on head and neck manifestations of eosinophilic granulomatosis with polyangiitis to guide clinical decision making for the otolaryngologist.
DATA SOURCES: PubMed, Cochrane Library, Scopus, and LILACS.
REVIEW METHODS: A systematic review of the aforementioned sources was conducted per the PRISMA guidelines.
RESULTS: From an initial 574 studies, 28 trials and reports were included, accounting for a total of 1175 patients with eosinophilic granulomatosis with polyangiitis. Among clinical and cohort studies, 48.0% to 96.0% of all included patients presented with head and neck manifestations. In a distinct group of patients detailed in case reports describing patients presenting with head and neck manifestations, patients on average fulfilled 4.6 diagnostic criteria per the American College of Rheumatology. Furthermore, 95.8% of reported cases were responsive to steroids, and 60% required additional therapy.
CONCLUSION: Otolaryngologists are in a unique position for the early diagnosis and prevention of late complications of eosinophilic granulomatosis with polyangiitis. The American College of Rheumatology criteria should be relied on in the diagnostic workup. Close surveillance of these patients in a multidisciplinary fashion and with baseline complete blood counts, chest radiographs, and autoimmune laboratory tests is often necessary. Such patients with head and neck manifestations of the disease are nearly always responsive to steroids and often require additional immunosuppressive therapy or surgical intervention in cases of cranial neuropathies, temporal bone involvement, and refractory symptoms
Frictional Behavior of Input Sediments to the Hikurangi Trench, New Zealand
AbstractThe Hikurangi subduction zone hosts shallow slowâslip events, possibly extending to the seafloor. The mechanisms allowing for this behavior are poorly understood but are likely a function of the frictional properties of the downgoing seafloor sediments. We conducted friction experiments at a large range of effective stresses, temperatures, and velocities on incoming sediment to the Hikurangi subduction zone to explore the possible connection of frictional properties to slowâslip events. These experiments were conducted on multiple apparatuses, allowing us to access a wider range of deformation conditions than is available on any one machine. We find that the material frictionally weakens and becomes less velocity strengthening with increasing effective stress, whereas temperature has only a small effect on both friction and frictional stability. When driven at the plate convergence rate, the sediment exhibits velocityâweakening behavior. These results imply that the frictional properties of the sediment package subducting at Hikurangi could promote slowâslip events at the pressures, temperatures, and strain rates expected along the plate boundary thrust up to 10âkm depth without requiring elevated pore fluid pressures. The transition to velocityâstrengthening behavior at faster slip rates could provide a mechanism for limiting unstable slip to slowâsliding velocities, rather than accommodating deformation through ordinary earthquakes
Quantum and Classical Disparity and Accord
Discrepancies and accords between quantum (QM) and classical mechanics (CM)
related to expectation values and periods are found for both the simple
harmonic oscillator (SHO) and a free particle in a box (FPB), which may apply
generally. These indicate non-locality is expected throughout QM. The FPB
energy states violate the Correspondence Principle. Previously unexpected
accords are found and proven that the classical and quantum expectation values
are the same for the expectation value of the second moment and the beat period
(i.e. beats between the phases for adjoining energy states) for the SHO for all
quantum numbers, n. However, for the FPB the beat periods differ significantly
at small n. It is shown that a particle's velocity in an infinite square well
varies, no matter how wide the box, nor how far the particle is from the walls.
The quantum free particle variances share an indirect commonality with the
Aharonov-Bohm and Aharonov-Casher effects in that there is a quantum action in
the absence of a force. The concept of an "Expectation Value over a Partial
Well Width" is introduced. This paper raises the question as to whether these
inconsistencies are undetectable, or can be empirically ascertained. These
inherent variances may need to be fixed, or nature is manifestly more
non-classical than expected.Comment: To be Published in International Journal of Theoretical Physics.
Published on line by IJTP 23 Sept.2008: Original at
http://www.springerlink.co
Keck Observatory Laser Guide Star Adaptive Optics Discovery and Characterization of a Satellite to the Large Kuiper Belt Object 2003 EL_(61)
The newly commissioned laser guide star adaptive optics system at Keck Observatory has been used to discover and characterize the orbit of a satellite to the bright Kuiper Belt object 2003 EL_(61). Observations over a 6 month period show that the satellite has a semimajor axis of 49,500 ± 400 km, an orbital period of 49.12 ± 0.03 days, and an eccentricity of 0.050 ± 0.003. The inferred mass of the system is (4.2 ± 0.1) à 10^(21) kg, or ~32% of the mass of Pluto and 28.6% ± 0.7% of the mass of the Pluto-Charon system. Mutual occultations occurred in 1999 and will not occur again until 2138. The orbit is fully consistent neither with one tidally evolved from an earlier closer configuration nor with one evolved inward by dynamical friction from an earlier more distant configuration
Basic Connection between Superconductivity and Superfluidity
A basic and inherently simple connection is shown to exist between
superconductivity and superfluidity. It is shown here that the author's
previously derived general equation which agrees well with the superconducting
transition temperatures for the heavy-electron superconductors, metallic
superconductors, oxide supercon- ductors, metallic hydrogen, and neutron stars,
also works well for the superfluid transition temperature of 2.6 mK for liquid
3He. Reasonable estimates are made from 10^-3 K to 10^9K -- a range of 12
orders of magnitude. The same paradigm applies to the superfluid transition
temperature of liquid 4He, but results in a slightly different equation. The
superfluid transition temperature for dilute solutions of 3He in superfluid 4He
is estimated to be ~ 1 to 10mK. This paradigm works well in detail for
metallic, cuprate, and organic superconductors.Comment: 16 pages, 2 figure
The QUEST large area CCD camera
We have designed, constructed, and put into operation a very large area CCD camera that covers the field of view of the 1.2 m Samuel Oschin Schmidt Telescope at the Palomar Observatory. The camera consists of 112 CCDs arranged in a mosaic of four rows with 28 CCDs each. The CCDs are 600 x 2400 pixel Sarnoff thinned, back-illuminated devices with 13 ”m x 13 ”m pixels. The camera covers an area of 4.6° x 3.6° on the sky with an active area of 9.6 deg_2. This camera has been installed at the prime focus of the telescope and commissioned, and scientific-quality observations on the Palomar-QUEST Variability Sky Survey were started in 2003 September. The design considerations, construction features, and performance parameters of this camera are described in this paper
The Rising Light Curves of Type Ia Supernovae
We present an analysis of the early, rising light curves of 18 Type Ia
supernovae (SNe Ia) discovered by the Palomar Transient Factory (PTF) and the
La Silla-QUEST variability survey (LSQ). We fit these early data flux using a
simple power-law to determine the time of first
light , and hence the rise-time from first light to
peak luminosity, and the exponent of the power-law rise (). We find a mean
uncorrected rise time of days, with individual SN rise-times
ranging from to days. The exponent n shows significant
departures from the simple 'fireball model' of (or ) usually assumed in the literature. With a mean value of , our data also show significant diversity from event to event. This
deviation has implications for the distribution of 56Ni throughout the SN
ejecta, with a higher index suggesting a lesser degree of 56Ni mixing. The
range of n found also confirms that the 56Ni distribution is not standard
throughout the population of SNe Ia, in agreement with earlier work measuring
such abundances through spectral modelling. We also show that the duration of
the very early light curve, before the luminosity has reached half of its
maximal value, does not correlate with the light curve shape or stretch used to
standardise SNe Ia in cosmological applications. This has implications for the
cosmological fitting of SN Ia light curves.Comment: 19 pages, 19 figures, accepted for publication in MNRA
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