1,155 research outputs found
Extending the Nested Parallel Model to the Nested Dataflow Model with Provably Efficient Schedulers
The nested parallel (a.k.a. fork-join) model is widely used for writing
parallel programs. However, the two composition constructs, i.e. ""
(parallel) and "" (serial), are insufficient in expressing "partial
dependencies" or "partial parallelism" in a program. We propose a new dataflow
composition construct "" to express partial dependencies in
algorithms in a processor- and cache-oblivious way, thus extending the Nested
Parallel (NP) model to the \emph{Nested Dataflow} (ND) model. We redesign
several divide-and-conquer algorithms ranging from dense linear algebra to
dynamic-programming in the ND model and prove that they all have optimal span
while retaining optimal cache complexity. We propose the design of runtime
schedulers that map ND programs to multicore processors with multiple levels of
possibly shared caches (i.e, Parallel Memory Hierarchies) and provide
theoretical guarantees on their ability to preserve locality and load balance.
For this, we adapt space-bounded (SB) schedulers for the ND model. We show that
our algorithms have increased "parallelizability" in the ND model, and that SB
schedulers can use the extra parallelizability to achieve asymptotically
optimal bounds on cache misses and running time on a greater number of
processors than in the NP model. The running time for the algorithms in this
paper is , where is the cache complexity of task ,
is the cost of cache miss at level- cache which is of size ,
is a constant, and is the number of processors in an
-level cache hierarchy
Torque vectoring based drive assistance system for turning an electric narrow tilting vehicle
The increasing number of cars leads to traffic congestion and limits parking issue in urban area. The narrow tilting vehicles therefore can potentially become the next generation of city cars due to its narrow width. However, due to the difficulty in leaning a narrow tilting vehicle, a drive assistance strategy is required to maintain its roll stability during a turn. This article presents an effective approach using torque vectoring method to assist the rider in balancing the narrow tilting vehicles, thus reducing the counter-steering requirements. The proposed approach is designed as the combination of two torque controllers: steer angle–based torque vectoring controller and tilting compensator–based torque vectoring controller. The steer angle–based torque vectoring controller reduces the counter-steering process via adjusting the vectoring torque based on the steering angle from the rider. Meanwhile, the tilting compensator–based torque vectoring controller develops the steer angle–based torque vectoring with an additional tilting compensator to help balancing the leaning behaviour of narrow tilting vehicles. Numerical simulations with a number of case studies have been carried out to verify the performance of designed controllers. The results imply that the counter-steering process can be eliminated and the roll stability performance can be improved with the usage of the presented approach
Vietnam’s Accession to the World Trade Organization: Economic Projections to 2020
This study presents a set of assessments of the long term economic effects of Vietnam’s accession to the WTO. Generally speaking, our results indicate that Vietnam would benefit from accelerating its participation in more open multilateralism. However, it is also clear from our analysis that these benefits will remain modest in the absence of comprehensive and complementary domestic economic reforms. Passive external liberalization, even when coupled with determined domestic reform, is inferior to WTO participation combined with negotiated market access and other activist multilateral agreements. Finally, our analysis shows that capital insufficiency is a very serious constraint on Vietnamese economic growth and diversification. Capital market reform can play an essential role in dynamic and sustained economic development for the country.Vietnam, WTO, Trade
Role of Electon Excitation and Nature of Molecular Gas in Cluster Central Elliptical Galaxies
We present observations in CO(3-2) that, combined with previous observations
in CO(2-1), constrain the physical properties of the filamentary molecular gas
in the central 6.5 kpc of NGC 1275, the central giant elliptical galaxy
of the Perseus cluster. We find this molecular gas to have a temperature
K and a density -, typically
warmer and denser than the bulk of Giant Molecular Clouds (GMCs) in the Galaxy.
Bathed in the harsh radiation and particle field of the surrounding
intracluster X-ray gas, the molecular gas likely has a much higher ionization
fraction than that of GMCs. For an ionization fraction of ,
similar to that of Galactic diffuse ()
partially-molecular clouds that emit in HCN(1-0) and HCO(1-0), we show that
the same gas traced in CO can produce the previously reported emissions in
HCN(3-2), HCO(3-2), and CN(2-1) from NGC 1275; the dominant source of
excitation for all the latter molecules is collisions with electrons. To
prevent collapse, as evidenced by the lack of star formation in the molecular
filaments, they must consist of thin strands that have cross-sectional radii
0.2-2 pc if supported solely by thermal gas pressure; larger radii
are permissible if turbulence or poloidal magnetic fields provide additional
pressure support. We point out that the conditions required to relate CO
luminosities to molecular gas masses in our Galaxy are unlikely to apply in
cluster central elliptical galaxies. Rather than being virialized structures
analogous to GMCs, we propose that the molecular gas in NGC 1275 comprises
pressure-confined structures created by turbulent flows.Comment: 41 pages, 1 table, 12 figures; accepted by Ap
Multiple Quantum Phases in Graphene with Enhanced Spin-Orbit Coupling: From the Quantum Spin Hall Regime to the Spin Hall Effect and a Robust Metallic State
We report an intriguing transition from the quantum spin Hall phase to the
spin Hall effect upon segregation of thallium adatoms adsorbed onto a graphene
surface. Landauer-B\"uttiker and Kubo-Greenwood simulations are used to access
both edge and bulk transport physics in disordered thallium-functionalized
graphene systems of realistic sizes. Our findings not only quantify the
detrimental effects of adatom clustering in the formation of the topological
state, but also provide evidence for the emergence of spin accumulation at
opposite sample edges driven by spin-dependent scattering induced by thallium
islands, which eventually results in a minimum bulk conductivity , insensitive to localization effects
Transcriptional down-regulation of suppressor of cytokine signaling (SOCS)-3 in chronic obstructive pulmonary disease
Background: Tobacco is a leading environmental factor in the initiation of respiratory diseases and causes chronic obstructive pulmonary disease (COPD). Suppressor of cytokine signaling (SOCS) family members are involved in the pathogenesis of many inflammatory diseases and SOCS-3 has been shown to play an important role in the regulation, onset and maintenance of airway allergic inflammation indicating that SOCS-3 displays a potential therapeutic target for anti-inflammatory respiratory drugs development. Since chronic obstructive pulmonary disease (COPD) is also characterized by inflammatory changes and airflow limitation, the present study assessed the transcriptional expression of SOCS-3 in COPD.
Methods: Real-time PCR was performed to assess quantitative changes in bronchial biopsies of COPD patients in comparison to unaffected controls.
Results: SOCS-3 was significantly down-regulated in COPD at the transcriptional level while SOCS-4 and SOCS-5 displayed no change.
Conclusions: It can be concluded that the presently observed inhibition of SOCS-3 mRNA expression may be related to the dysbalance of cytokine signaling observed in COPD
Causal Pluralism in Philosophy: Empirical Challenges and Alternative Proposals
An increasing number of arguments for causal pluralism invoke empirical psychological data. Different aspects of causal cognition-specifically, causal perception and causal inference-are thought to involve distinct cognitive processes and representations, and they thereby distinctively support transference and dependency theories of causation, respectively. We argue that this dualistic picture of causal concepts arises from methodological differences, rather than from an actual plurality of concepts. Hence, philosophical causal pluralism is not particularly supported by the empirical data. Serious engagement with cognitive science reveals that the connection between psychological concepts of causation and philosophical notions is substantially more complicated than is traditionally presumed
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