1,241,815 research outputs found
Dynamics of an experimental two bladed horizontal axis wind turbine with blade cyclic pitch variation
The turbine under study incorporates the combination of two features: the application of blade cyclic pitch variation; and the use of yaw angle control for rotor speed and torque regulation. Due to its emasculation by passive cyclic pitch variation the rotor can be rapidly yawed without encountering gyroscopic and aerodynamic hub moments and without noticeable out of plane excursions. The two bladed upwind rotor is vane stabilized and of very simple and rugged design. The principle was first checked out with a small scale wind tunnel model and then tested in the atmosphere with a 7.6 meter diameter experimental fully instrumented wind turbine driving a 3 phase alternator. The test results are summarized with respect to structural dynamics and yaw dynamics
Spectral Sum Rules of the Dirac operator and Partially Quenched Chiral Condensates
Exploiting Virasoro constraints on the effective finite-volume partition
function, we derive generalized Leutwyler-Smilga spectral sum rules of the
Dirac operator to high order. By introducing fermion species of equal
masses, we next use the Virasoro constraints to compute two (low-mass and
large-mass) expansions of the partially quenched chiral condensate through the
replica method of letting . The low-mass expansion can only be
pushed to a certain finite order due to de Wit-'t Hooft poles, but the
large-mass expansion can be carried through to arbitrarily high order. Results
agree exactly with earlier results obtained through both Random Matrix Theory
and the supersymmetric method.Comment: LaTeX, 19 pages, misprints correcte
Differential Diagnoses of Systemic Mastocytosis in Routinely Processed Bone Marrow Biopsy Specimens: A Review
Diagnosis of systemic mastocytosis (SM) is mainly based on the morphological demonstration of compact mast cell infiltrates in various tissue sites. In almost all patients such infiltrates are detected in the bone marrow. Reliable immunohistochemical markers for the diagnosis and grading of SM have been established, but various differential diagnoses including myeloproliferative neoplasms, basophilic and eosinophilic leukemias may be very difficult to delineate. Even more challenging is the recognition of hematological neoplasms with signs of mast cell differentiation but not fulfilling diagnostic criteria for SM, especially the rare myelomastocytic leukemia. It is also important to separate the reactive state of mast cell hyperplasia from indolent variants of SM, especially those with a very low degree of bone marrow infiltration and absence of compact mast cell infiltrates. When the lymphocytic component of the SM infiltrate is very prominent, SM may be confused with an indolent lymphoma, especially lymphoplasmacytic lymphoma which almost always shows a marked reactive increase in mast cells. In aggressive and leukemic variants of SM, mast cells may be very atypical and devoid of metachromatic granules. This hypogranulation can be regarded as cellular atypia and may lead to the misdiagnosis aspect of monocytic leukemia or histiocytic neoplasm. Regarding immunohistochemical anomalies, mast cells in aggressive and leukemic SM have been found to express CD30 (Ki1-antigen). Thus, anaplastic large cell lymphoma or Hodgkin's disease may first be considered rather than SM. There is increasing evidence that most patients with long-standing adult-type urticaria pigmentosalike skin lesions have in fact indolent SM. Therefore, such skin lesions are an important clue to the correct diagnosis in these patients. However, in aggressive or leukemic SM skin lesions are usually absent and then the correct diagnosis relies on an appropriate investigation of bone marrow biopsy specimens using both SM-related immunohistochemical markers (tryptase, KIT, CD25, CD30) but also markers excluding potential differential diagnoses. Investigation for presence of the activating KIT point mutation D816V is very helpful to establish a correct diagnosis of SM in all the difficult cases exhibiting a low degree of bone marrow infiltration or puzzling morphological findings. Copyright (C) 2010 S. Karger AG, Base
Reconstruction of the finite size canonical ensemble from incomplete micro-canonical data
In this paper we discuss how partial knowledge of the density of states for a
model can be used to give good approximations of the energy distributions in a
given temperature range. From these distributions one can then obtain the
statistical moments corresponding to eg the internal energy and the specific
heat. These questions have gained interest apropos of several recent methods
for estimating the density of states of spin models. As a worked example we
finally apply these methods to the 3-state Potts model for cubic lattices of
linear order up to 128. We give estimates of eg latent heat and critical
temperature, as well as the microcanonical properties of interest.Comment: 19 page
The discontinuity of the specific heat for the 5D Ising model
In this paper we investigate the behaviour of the specific heat around the
critical point of the Ising model in dimension 5 to 7. We find a specific heat
discontinuity, like that for the mean field Ising model, and provide estimates
for the left and right hand limits of the specific heat at the critical point.
We also estimate the singular exponents, describing how the specific heat
approaches those limits. Additionally, we make a smaller scale investigation of
the same properties in dimension 6 and 7, and provide strongly improved
estimates for the critical termperature in which bring the best
MC-estimate closer to those obtained by long high temperature series expanions.Comment: 8 pages, 13 figure
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