1,188 research outputs found
Microwave whirlpools in a rectangular-waveguide cavity with a thin ferrite disk
We study a three dimensional system of a rectangular-waveguide resonator with
an inserted thin ferrite disk. The interplay of reflection and transmission at
the disk interfaces together with material gyrotropy effect, gives rise to a
rich variety of wave phenomena. We analyze the wave propagation based on full
Maxwell-equation numerical solutions of the problem. We show that the
power-flow lines of the microwave-cavity field interacting with a ferrite disk,
in the proximity of its ferromagnetic resonance, form whirlpool-like
electromagnetic vortices. Such vortices are characterized by the dynamical
symmetry breaking. The role of ohmic losses in waveguide walls and dielectric
and magnetic losses in a disk is a subject of our investigations
Simple and Rapid Quantification of Thrombocytes in Zebrafish Larvae
Platelets are a critical component of hemostasis, with disorders of number or function resulting in coagulation disturbances. Insights into these processes have primarily been realized through studies using mammalian models or tissues. Increasingly, zebrafish embryos and larvae have been used to study the protein and cellular components of hemostasis and thrombosis, including the thrombocyte, a nucleated platelet analog. However, investigations of thrombocytes have been somewhat limited due to lack of a robust and simple methodology for quantitation, an important component of platelet studies in mammals. Using video capture, we have devised an assay that produces a rapid, reproducible, and precise measurement of thrombocyte number in zebrafish larvae by counting fluorescently tagged cells. Averaging 1000 frames, we were able to subtract background fluorescence, thus limiting assessment to circulating thrombocytes. This method facilitated rapid assessment of relative thrombocyte counts in a population of 372 zebrafish larvae by a single operator in less than 3 days. This technique requires basic microscopy equipment and rudimentary programming, lends itself to high throughput analysis, and will enhance future studies of thrombopoiesis in the zebrafish.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140302/1/zeb.2014.1079.pd
Bubble formation and growth - Study of the boundary conditions at the bubble wall through irreversible thermodynamics Progress report, 17 Feb. - 30 May 1965
Spherical bubble growth or collapse in component inviscid liquid with constant material properties through irreversible thermodynamics and kinetic theor
Admit your weakness: Verifying correctness on TSO architectures
“The final publication is available at http://link.springer.com/chapter/10.1007%2F978-3-319-15317-9_22 ”.Linearizability has become the standard correctness criterion for fine-grained non-atomic concurrent algorithms, however, most approaches assume a sequentially consistent memory model, which is not always realised in practice. In this paper we study the correctness of concurrent algorithms on a weak memory model: the TSO (Total Store Order) memory model, which is commonly implemented by multicore architectures. Here, linearizability is often too strict, and hence, we prove a weaker criterion, quiescent consistency instead. Like linearizability, quiescent consistency is compositional making it an ideal correctness criterion in a component-based context. We demonstrate how to model a typical concurrent algorithm, seqlock, and prove it quiescent consistent using a simulation-based approach. Previous approaches to proving correctness on TSO architectures have been based on linearizabilty which makes it necessary to modify the algorithm’s high-level requirements. Our approach is the first, to our knowledge, for proving correctness without the need for such a modification
Evolution of Collective Motion in a Model Glass-Forming Liquid During Physical Aging
At temperatures moderately below their glass transition temperature, the properties of many glassforming materials can evolve slowly with time in a process known as physical aging whereby the thermodynamic, mechanical, and dynamic properties all drift towards their equilibrium values. In this work, we study the evolution of the thermodynamic and dynamic properties during physical aging for a model polymer glass. Specifically, we test the relationship between an estimate of the size of the cooperative rearrangements taking the form of strings and the effective structural relaxation time predicted by the Adam-Gibbs relationship for both an equilibrium supercooled liquid and the same fluid undergoing physical aging towards equilibrium after a series of temperature jumps. We find that there is apparently a close correlation between a structural feature of the fluid, the size of the string-like rearrangements, and the structural relaxation time, although the relationship for the aging fluid appears to be distinct from that of the fluid at equilibrium
Correctness of an STM Haskell implementation
A concurrent implementation of software transactional memory in Concurrent Haskell using a call-by-need functional language with processes and futures is given. The description of the small-step operational semantics is precise and explicit, and employs an early abort of conflicting transactions. A proof of correctness of the implementation is given for a contextual semantics with may- and should-convergence. This implies that our implementation is a correct evaluator for an abstract specification equipped with a big-step semantics
Emicizumab prophylaxis to facilitate anticoagulant therapy for management of intra‐atrial thrombosis in severe haemophilia with an inhibitor
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149546/1/hae13721.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149546/2/hae13721_am.pd
Open Transactions on Shared Memory
Transactional memory has arisen as a good way for solving many of the issues
of lock-based programming. However, most implementations admit isolated
transactions only, which are not adequate when we have to coordinate
communicating processes. To this end, in this paper we present OCTM, an
Haskell-like language with open transactions over shared transactional memory:
processes can join transactions at runtime just by accessing to shared
variables. Thus a transaction can co-operate with the environment through
shared variables, but if it is rolled-back, also all its effects on the
environment are retracted. For proving the expressive power of TCCS we give an
implementation of TCCS, a CCS-like calculus with open transactions
Tolerating Faults in Counting Networks
Counting networks were proposed by Aspnes, Herlihy and Shavit [4] as a technique
for solving multiprocessor coordination problems. We describe a method for tolerating an
arbitrary number of faults in counting networks. In our fault model, the following errors can occur
dynamically in the counting network data structure: 1) a balancer's state is spuriously altered, 2)
a balancer's state can no longer be accessed.
We propose two approaches for tolerating faults. The first is based on a construction for a
fault-tolerant balancer. We substitute a fault-tolerant balancer for every balancer in a counting
network. Thus, we transform a counting network with depth O(log to the power of 2 n); where n is the
width, into a k-fault-tolerant counting network with depth O(k log to the power of 2 n).
The second approach is to append a correction network, built with fault-tolerant balancers, to a
counting network that may experience faults. We present a bound on the error in the output token
distribution of counting networks with faulty balancers (a generalization of the error bound for
sorting networks with faulty comparators presented by Yao & Yao [21]. Given a token distribution
with a bounded error, the correction network produces a token distribution that is smooth, i.e.,
the number of tokens on each output wire differs by at most one (a weaker condition than the
step property). In order to tolerate k faults, the correction network has depth O (k to the power of 2
log n) for a network of width n
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