464 research outputs found
Estimating the Permanent Growth Effects of Human Capital
This paper estimates with the least trimmed least squares (LTS) a specification suitable to estimate the permanent growth effects of human capital, using educational attainment (H) as a proxy. Our results show that H has significant permanent growth effects but these are much smaller than in Temple (1999).Least Trimmed Squares, Human capital, Educational attainment, Permanent growth effects
Estimates of the long-run growth rate of Singapore with a CES production function
This paper estimates with the Bayesian methods a CES production function for Singapore for 1960-2009. It is found that the elasticity of substitution is 0.6, technical progress is labour augmenting and the steady state growth rate of Singapore is about 1.8%.Bayesian methods, CES production function and Technical progress
Active elastic dimers: self-propulsion and current reversal on a featureless track
We present a Brownian inchworm model of a self-propelled elastic dimer in the
absence of an external potential. Nonequilibrium noise together with a
stretch-dependent damping form the propulsion mechanism. Our model connects
three key nonequilibrium features -- position-velocity correlations, a nonzero
mean internal force, and a drift velocity. Our analytical results, including
striking current reversals, compare very well with numerical simulations. The
model unifies the propulsion mechanisms of DNA helicases, polar rods on a
vibrated surface, crawling keratocytes and Myosin VI. We suggest experimental
realizations and tests of the model.Comment: 4 page
Activating membranes
We present a general dynamical theory of a membrane coupled to an actin
cortex containing polymerizing filaments with active stresses and currents, and
demonstrate that active membrane dynamics [Phys. Rev. Lett \textbf{84}, 3494
(2000)] and spontaneous shape oscillations emerge from this description. We
also consider membrane instabilities and patterns induced by the presence of
filaments with polar orientational correlations in the tangent plane of the
membrane. The dynamical features we predict should be seen in a variety of
cellular contexts involving the dynamics of the membrane-cytoskeleton composite
and cytoskeletal extracts coupled to synthetic vesicles
Anti-correlated time lags in the Z source GX 5-1: Possible evidence for a truncated accretion disk
We investigate the nature of the inner accretion disk in the neutron star
source GX 5-1 by making a detailed study of time lags between X-rays of
different energies. Using the cross-correlation analysis, we found
anti-correlated hard and soft time lags of the order of a few tens to a few
hundred seconds and the corresponding intensity states were mostly the
horizontal branch (HB) and upper normal branch (NB). The model independent and
dependent spectral analysis showed that during these time lags the structure of
accretion disk significantly varied. Both eastern and western approaches were
used to unfold the X-ray continuum and systematic changes were observed in soft
and hard spectral components. These changes along with a systematic shift in
the frequency of quasi-periodic oscillations (QPOs) made it substantially
evident that the geometry of the accretion disk is truncated. Simultaneous
energy spectral and power density spectral study shows that the production of
the horizontal branch oscillations (HBOs) are closely related to the
Comptonizing region rather than the disk component in the accretion disk. We
found that as the HBO frequency decreases from the hard apex to upper HB, the
disk temperature increases along with an increase in the coronal temperature
which is in sharp contrast with the changes found in black hole binaries where
the decrease in QPO frequency is accompanied by a decrease in the disk
temperature and a simultaneous increase in the coronal temperature. We discuss
the results in the context of re-condensation of coronal material in the inner
region of the disk.Comment: 40 pages, 7 figures, accepted for publication in The Astrophysical
Journal Supplement (ApJS
DCCast: Efficient Point to Multipoint Transfers Across Datacenters
Using multiple datacenters allows for higher availability, load balancing and
reduced latency to customers of cloud services. To distribute multiple copies
of data, cloud providers depend on inter-datacenter WANs that ought to be used
efficiently considering their limited capacity and the ever-increasing data
demands. In this paper, we focus on applications that transfer objects from one
datacenter to several datacenters over dedicated inter-datacenter networks. We
present DCCast, a centralized Point to Multi-Point (P2MP) algorithm that uses
forwarding trees to efficiently deliver an object from a source datacenter to
required destination datacenters. With low computational overhead, DCCast
selects forwarding trees that minimize bandwidth usage and balance load across
all links. With simulation experiments on Google's GScale network, we show that
DCCast can reduce total bandwidth usage and tail Transfer Completion Times
(TCT) by up to compared to delivering the same objects via independent
point-to-point (P2P) transfers.Comment: 9th USENIX Workshop on Hot Topics in Cloud Computing,
https://www.usenix.org/conference/hotcloud17/program/presentation/noormohammadpou
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