934 research outputs found
Forecasting Intermittent Demand by Hyperbolic-Exponential Smoothing
Croston's method is generally viewed as superior to exponential smoothing
when demand is intermittent, but it has the drawbacks of bias and an inability
to deal with obsolescence, in which an item's demand ceases altogether. Several
variants have been reported, some of which are unbiased on certain types of
demand, but only one recent variant addresses the problem of obsolescence. We
describe a new hybrid of Croston's method and Bayesian inference called
Hyperbolic-Exponential Smoothing, which is unbiased on non-intermittent and
stochastic intermittent demand, decays hyperbolically when obsolescence occurs
and performs well in experiments.Comment: Earlier versions of this work were presented at the 25th European
Conference on Operations Research, 2012; and at the 54th Annual Conference of
the UK Operational Research Society, 2012. A journal version is in
preparatio
Clinical trial of lamivudine in children with chronic hepatitis B.
N Engl J Med. 2002 May 30;346(22):1706-13.
Clinical trial of lamivudine in children with chronic hepatitis B.
Jonas MM, Mizerski J, Badia IB, Areias JA, Schwarz KB, Little NR, Greensmith MJ, Gardner SD, Bell MS, Sokal EM; International Pediatric Lamivudine Investigator Group.
of Gastroenterology, Children's Hospital, Boston, MA 02115, USA.
Erratum in:
N Engl J Med 2002 Sep 19;347(12):955. Kelley, Deirdre [corrected to Kelly, Deirdre].
Comment in:
J Hepatol. 2003 May;38(5):698-9.
N Engl J Med. 2002 May 30;346(22):1682-3.
Abstract
BACKGROUND: Lamivudine therapy is effective for chronic hepatitis B infection in adults. We evaluated the efficacy and tolerability of lamivudine as a treatment for chronic infection with hepatitis B virus (HBV) in children.
METHODS: Children with chronic hepatitis B were randomly assigned in a 2:1 ratio to receive either oral lamivudine (3 mg per kilogram of body weight; maximum, 100 mg) or placebo once daily for 52 weeks. The primary end point was virologic response (defined by the absence of serum hepatitis B e antigen and serum HBV DNA) at week 52 of treatment.
RESULTS: Of the 403 children screened, 191 were randomly assigned to receive lamivudine and 97 to receive placebo. The rate of virologic response at week 52 was higher among children who received lamivudine than among those who received placebo (23 percent vs. 13 percent, P=0.04). Lamivudine therapy was well tolerated and was also associated with higher rates of seroconversion from hepatitis B e antigen to hepatitis B e antibody, normalization of alanine aminotransferase levels, and suppression of HBV DNA.
CONCLUSIONS: In children with chronic hepatitis B, 52 weeks of treatment with lamivudine was associated with a significantly higher rate of virologic response than was placebo.
PMID: 12037150 [PubMed - indexed for MEDLINE
Rescattering and chiral dynamics in B\to \rho\pi decay
We examine the role of B^0(\bar B^0) \to \sigma \pi^0 \to \pi^+\pi^- \pi^0
decay in the Dalitz plot analysis of B^0 (\bar B^0) \to \rho\pi \to
\pi^+\pi^-\pi^0 decays, employed to extract the CKM parameter \alpha. The
\sigma \pi channel is significant because it can break the relationship between
the penguin contributions in B\to\rho^0\pi^0, B\to\rho^+\pi^-, and
B\to\rho^-\pi^+ decays consequent to an assumption of isospin symmetry. Its
presence thus mimics the effect of isospin violation. The \sigma\pi^0 state is
of definite CP, however; we demonstrate that the B\to\rho\pi analysis can be
generalized to include this channel without difficulty. The \sigma or
f_0(400-1200) ``meson'' is a broad I=J=0 enhancement driven by strong \pi\pi
rescattering; a suitable scalar form factor is constrained by the chiral
dynamics of low-energy hadron-hadron interactions - it is rather different from
the relativistic Breit-Wigner form adopted in earlier B\to\sigma\pi and
D\to\sigma\pi analyses. We show that the use of this scalar form factor leads
to an improved theoretical understanding of the measured ratio Br(\bar B^0 \to
\rho^\mp \pi^\pm) / Br(B^-\to \rho^0 \pi^-).Comment: 26 pages, 8 figs, published version. typos fixed, minor change
3D visualisation of voids in grapevine flowers and berries using Xâray micro computed tomography
First published: 06 January 2021Background and Aim: X-ray micro computed tomography (micro-CT) is a non-destructive 3D imaging technique that has been applied to plant morphology and anatomical studies to gain a better understanding of physiological phenomena in vivo. It is particularly useful for imaging voids in undisturbed fragile tissues and therefore may be applied to the delicate flowers and soft berries of Vitis vinifera. The characterisation of gas spaces and channels can offer insights into the process of tissue aeration and this may have implications on cell function and vitality. We assessed the use of micro-CT to visualise voids within these reproductive organs. Methods and Results: The internal structures of flowers and berries were captured through rapid micro-CT scanning and subsequently were recreated in 3D using image processing. The relative positions of the developing flower parts encased within the flower cap were visualised. Low density/porous tissue was identified within the pedicel and receptacle, con- necting the lenticels with the interior of the berry. Voids were present in the proximal mesocarp of mature berries forming a âdetachment zoneâ in both seeded and seedless cultivars. Voids permeated the mesocarp of mature seedless grape cultivars, but not seeded grapes. Conclusion: Micro-CT offers new insights regarding the distribution of voids on the morphology and compositional hetero- geneity of organs that are difficult to dissect and/or view with light microscopy. Significance of the Study: A better understanding of the physiology and functionality of grapevine reproductive tissues may be achieved by 3D visualisation of internal structure in vivo.Z. Xiao, T. Stait-Gardner, S.A. Willis, W.S. Price, F.J. Moroni, V. Pagay ⊠et al
The Dipion Mass Spectrum In e+e- Annihilation and tau Decay: A Dynamical (rho0, omega, phi) Mixing Approach
We readdress the problem of finding a simultaneous description of the pion
form factor data in e+e- annihilations and in tau decays. For this purpose, we
work in the framework of the Hidden Local Symmetry (HLS) Lagrangian and modify
the vector meson mass term by including the pion and kaon loop contributions.
This leads us to define the physical rho, omega and phi fields as linear
combinations of their ideal partners, with coefficients being meromorphic
functions of s, the square of the 4--momentum flowing into the vector meson
lines. This allows us to define a dynamical, i.e. s-dependent, vector meson
mixing scheme. The model is overconstrained by extending the framework in order
to include the description of all meson radiative (V P gamma and P gamma gamma
couplings) and leptonic (Ve+e- couplings) decays and also the isospin breaking
(omega/ phi --> pi+ pi-) decay modes. The model provides a simultaneous,
consistent and good description of the e+e- and tau dipion spectra. The
expression for pion form factor in the latter case is derived from those in the
former case by switching off the isospin breaking effects specific to e+e- and
switching on those for tau decays. Besides, the model also provides a good
account of all decay modes of the form V P gamma, Pgamma gamma as well as the
isospin breaking decay modes. It leads us to propose new reference values for
the rho^0 --> e+ e- and omega --> pi+ pi- partial widths which are part of our
description of the pion form factor. Other topics (phi --> K anti K, the rho
meson mass and width parameters) are briefly discussed. Therefore, we confirm
the 3.3 sigma discrepancy between the theoretical estimate of a_mu based on
e+e- and its direct BNL measurement.Comment: 71 pages, 8 figures. Accepted by EPJ C. Version 3: correct minor
typos, minor changes spread out into the text. Extension of Sections 12.2 and
12.3.5 and introduction of the new Appendix
Couplings of light I=0 scalar mesons to simple operators in the complex plane
The flavour and glue structure of the light scalar mesons in QCD are probed
by studying the couplings of the I=0 mesons and to the
operators , and to two photons. The Roy dispersive
representation for the amplitude is used to determine the
pole positions as well as the residues in the complex plane. On the real axis,
is constrained to solve the Roy equation together with elastic
unitarity up to the K\Kbar threshold leading to an improved description of
the . The problem of using a two-particle threshold as a matching
point is discussed. A simple relation is established between the coupling of a
scalar meson to an operator and the value of the related pion form-factor
computed at the resonance pole. Pion scalar form-factors as well as two-photon
partial-wave amplitudes are expressed as coupled-channel Omn\`es dispersive
representations. Subtraction constants are constrained by chiral symmetry and
experimental data. Comparison of our results for the couplings with
earlier determinations of the analogous couplings of the lightest I=1 and
scalar mesons are compatible with an assignment of the ,
, , into a nonet. Concerning the gluonic operator
we find a significant coupling to both the and the
.Comment: 31 pages, 5 figure
The Labour of Love: Seasonal Migration from Jharkhand to the Brick Kilns of Other States in India
Seasonal casual labour migration in India has conventionally been understood as the result of extreme poverty whereby villagers are forced to become migrants for the dry six months to subsist or merely survive. This article draws on fieldwork in a village in Jharkhand and a brick kiln in West Bengal to argue that migrants do not understand their movement in economic terms alone. Many see the brick kilns as a temporary space of freedom to escape problems back home, explore a new country, gain independence from parents or live out prohibited amorous relationships. It is suggested that Jharkhandi activists and policy-makersâ construction of such migration as a âproblemâ is as much about their vision of how the new tribal state ought to be as about exploitation. Migration to the kilns is seen by them as a threat to the purity and regulation of the social and sexual tribal citizen. This moralising perspective creates a climate that paradoxically encourages many young people to flee to the brick kilns where they can live âfreelyâ. In this way, the new puritanism at home helps to reproduce the conditions for capitalist exploitation and the extraction of surplus value
Young and Intermediate-age Distance Indicators
Distance measurements beyond geometrical and semi-geometrical methods, rely
mainly on standard candles. As the name suggests, these objects have known
luminosities by virtue of their intrinsic proprieties and play a major role in
our understanding of modern cosmology. The main caveats associated with
standard candles are their absolute calibration, contamination of the sample
from other sources and systematic uncertainties. The absolute calibration
mainly depends on their chemical composition and age. To understand the impact
of these effects on the distance scale, it is essential to develop methods
based on different sample of standard candles. Here we review the fundamental
properties of young and intermediate-age distance indicators such as Cepheids,
Mira variables and Red Clump stars and the recent developments in their
application as distance indicators.Comment: Review article, 63 pages (28 figures), Accepted for publication in
Space Science Reviews (Chapter 3 of a special collection resulting from the
May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space
Age
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