190,485 research outputs found
Book Review: âASIA ON TOUR: Exploring the rise of Asian tourismâ
A review of the book "Asia on Tour: Exploring the Rise of Asian Tourism," edited by Tim Winter, Peggy Teo and T. C. Chang is presented
On The Panel Unit Root Tests Using Nonlinear Instrumental Variables
This paper re-examines the panel unit root tests proposed by Chang (2002). She establishes asymptotic independence of the t-statistics when integrable functions of lagged dependent variable are used as instruments even if the original series are cross sectionally dependent. She claims that her non-linear instrumental variable (NIV) panel unit root test is valid under general error cross correlations for any N (the cross section dimension) as T (the time dimension of the panel) tends to infinity. These results are largely due to her particular choice of the error correlation matrix which results in weak cross section dependence. Also, the asymptotic independence property of the t- statistics disappears when Chang's modified instruments are used. Using a common factor model with a sizeable degree of cross section correlations, we show that Chang's NIV panel unit root test suffers from gross size distortions, even when N is small relative to T
In search of a Hagedorn transition in SU(N) lattice gauge theories at large-N
We investigate on the lattice the metastable confined phase above Tc in SU(N)
gauge theories, for N=8,10, and 12. In particular we focus on the decrease with
the temperature of the mass of the lightest state that couples to Polyakov
loops. We find that at T=Tc the corresponding effective string tension
\sigma_{eff}(T) is approximately half its value at T=0, and that as we increase
T beyond Tc, while remaining in the confined phase, \sigma_{eff}(T) continues
to decrease. We extrapolate \sigma_{eff}(T) to even higher temperatures, and
interpret the temperature where it vanishes as the Hagedorn temperature T_H.
For SU(12) we find that T_H/Tc=1.116(9), when we use the exponent of the
three-dimensional XY model for the extrapolation, which seems to be slightly
preferred over a mean-field exponent by our data.Comment: 20 pages, 12 figures. New version includes: a more extensive error
analysis, a discussion on the behavior of masses near T_H, and additional
acknowledgements and references. Results and conclusions do not chang
Stereotactic ablative body radiotherapy for the treatment of spinal oligometastases
Abstract not availableJ.H. Chang, S. Gandhidasan, R. Finnigan, D. Whalley, R. Nair, A. Herschtal, T. Eade, A. Kneebone, J. Ruben, M. Foote, S. Siv
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N-Dimensional Perfect Pipelining
In this paper, we introduce a technique to parallelize nested loops at the fine grain level. It is a generalization of Perfect Pipelining which was developed to parallelize a single-nested loop at the fine grain level. Previous techniques that can parallelize nested loops, e.g. DOACROSS or Wavefront method, mostly belong to the coarse grain approach. We explain our method, contrast it with the coarse grain techniques, and show the benefits of parallelizing nested loops at the fine grain level
Gauge Independent Trace Anomaly for Gravitons
We show that the trace anomaly for gravitons calculated using the usual
effective action formalism depends on the choice of gauge when the background
spacetime is not a solution of the classical equation of motion, that is, when
off-shell. We then use the gauge independent Vilkovisky-DeWitt effective action
to restore gauge independence to the off-shell case. Additionally we explicitly
evaluate trace anomalies for some N-sphere background spacetimes.Comment: 19 pages, additional references and title chang
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Fine grain software pipelining of non-vectorizable nested loops
This paper presents a new technique to parallelize nested loops at the statement level. It transforms sequential nested loops, either vectorizable or not, into parallel ones. Previously, the wavefront method was used to parallelize non-vectorizable nested loops. However, in order to reduce the complexity of parallelization, the wavefront method regards an iteration as an unbreakable scheduling unit and draws parallelism through iteration overlapping. Our technique takes a statement rather than an iteration as the scheduling unit and exploits parallelism by overlapping the statements in all dimensions. In this paper, we show how this finer grain parallelization can be achieved with reasonable computational complexity, and the effectiveness of the resulting method in exploiting parallelism
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