8,775 research outputs found
Allocating the fixed cost:an approach based on data envelopment analysis and cooperative game
Allocating the fixed cost among a set of users in a fair way is an important issue both in management and economic research. Recently, Du et al. (Eur J Oper Res 235(1): 206–214, 2014) proposed a novel approach for allocating the fixed cost based on the game cross-efficiency method by taking the game relations among users in efficiency evaluation. This paper proves that the novel approach of Du et al. (Eur J Oper Res 235(1): 206–214, 2014) is equivalent to the efficiency maximization approach of Li et al. (Omega 41(1): 55–60, 2013), and may exist multiple optimal cost allocation plans. Taking into account the game relations in the allocation process, this paper proposes a cooperative game approach, and uses the nucleolus as a solution to the proposed cooperative game. The proposed approach in this paper is illustrated with a dataset from the prior literature and a real dataset of a steel and iron enterprise in China
Structure of hadron resonances with a nearby zero of the amplitude
We discuss the relation between the analytic structure of the scattering
amplitude and the origin of an eigenstate represented by a pole of the
amplitude.If the eigenstate is not dynamically generated by the interaction in
the channel of interest, the residue of the pole vanishes in the zero coupling
limit. Based on the topological nature of the phase of the scattering
amplitude, we show that the pole must encounter with the
Castillejo-Dalitz-Dyson (CDD) zero in this limit. It is concluded that the
dynamical component of the eigenstate is small if a CDD zero exists near the
eigenstate pole. We show that the line shape of the resonance is distorted from
the Breit-Wigner form as an observable consequence of the nearby CDD zero.
Finally, studying the positions of poles and CDD zeros of the KbarN-piSigma
amplitude, we discuss the origin of the eigenstates in the Lambda(1405) region.Comment: 7 pages, 3 figures, v2: published versio
Imprints of Nuclear Symmetry Energy on Properties of Neutron Stars
Significant progress has been made in recent years in constraining the
density dependence of nuclear symmetry energy using terrestrial nuclear
laboratory data. Around and below the nuclear matter saturation density, the
experimental constraints start to merge in a relatively narrow region. At
supra-saturation densities, there are, however, still large uncertainties.
After summarizing the latest experimental constraints on the density dependence
of nuclear symmetry energy, we highlight a few recent studies examining
imprints of nuclear symmetry energy on the binding energy, energy release
during hadron-quark phase transitions as well as the -mode frequency and
damping time of gravitational wave emission of neutron stars.Comment: 10 pages. Invited talk given in the Nuclear Astrophysics session of
INPC2010, July 4-9, 2010, Vancouver, Canada; Journal of Physics: Conference
Series (2011
Lower cerebrospinal fluid/plasma fibroblast growth factor 21 (FGF21) ratios and placental FGF21 production in gestational diabetes
Objectives: Circulating Fibroblast Growth Factor 21 (FGF21) levels are increased in insulin resistant states such as obesity, type 2 diabetes mellitus and gestational diabetes mellitus (GDM). In addition, GDM is associated with serious maternal and fetal complications. We sought to study human cerebrospinal fluid (CSF) and corresponding circulating FGF21 levels in women with gestational diabetes mellitus (GDM) and in age and BMI matched control subjects. We also assessed FGF21 secretion from GDM and control human placental explants.
Design: CSF and corresponding plasma FGF21 levels of 24 women were measured by ELISA [12 GDM (age: 26–47 years, BMI: 24.3–36.3 kg/m2) and 12 controls (age: 22–40 years, BMI: 30.1–37.0 kg/m2)]. FGF21 levels in conditioned media were secretion from GDM and control human placental explants were also measured by ELISA.
Results: Glucose, HOMA-IR and circulating NEFA levels were significantly higher in women with GDM compared to control subjects. Plasma FGF21 levels were significantly higher in women with GDM compared to control subjects [234.3 (150.2–352.7) vs. 115.5 (60.5–188.7) pg/ml; P<0.05]. However, there was no significant difference in CSF FGF21 levels in women with GDM compared to control subjects. Interestingly, CSF/Plasma FGF21 ratio was significantly lower in women with GDM compared to control subjects [0.4 (0.3–0.6) vs. 0.8 (0.5–1.6); P<0.05]. FGF21 secretion into conditioned media was significantly lower in human placental explants from women with GDM compared to control subjects (P<0.05).
Conclusions: The central actions of FGF21 in GDM subjects maybe pivotal in the pathogenesis of insulin resistance in GDM subjects. The significance of FGF21 produced by the placenta remains uncharted and maybe crucial in our understanding of the patho-physiology of GDM and its associated maternal and fetal complications. Future research should seek to elucidate these points
Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay
The Daya Bay experiment has observed correlations between reactor core fuel
evolution and changes in the reactor antineutrino flux and energy spectrum.
Four antineutrino detectors in two experimental halls were used to identify 2.2
million inverse beta decays (IBDs) over 1230 days spanning multiple fuel cycles
for each of six 2.9 GW reactor cores at the Daya Bay and Ling
Ao nuclear power plants. Using detector data spanning effective Pu
fission fractions, , from 0.25 to 0.35, Daya Bay measures an average
IBD yield, , of
cm/fission and a fuel-dependent variation in the IBD yield,
, of cm/fission.
This observation rejects the hypothesis of a constant antineutrino flux as a
function of the Pu fission fraction at 10 standard deviations. The
variation in IBD yield was found to be energy-dependent, rejecting the
hypothesis of a constant antineutrino energy spectrum at 5.1 standard
deviations. While measurements of the evolution in the IBD spectrum show
general agreement with predictions from recent reactor models, the measured
evolution in total IBD yield disagrees with recent predictions at 3.1.
This discrepancy indicates that an overall deficit in measured flux with
respect to predictions does not result from equal fractional deficits from the
primary fission isotopes U, Pu, U, and Pu.
Based on measured IBD yield variations, yields of and cm/fission have been determined for the two
dominant fission parent isotopes U and Pu. A 7.8% discrepancy
between the observed and predicted U yield suggests that this isotope
may be the primary contributor to the reactor antineutrino anomaly.Comment: 7 pages, 5 figure
A side-by-side comparison of Daya Bay antineutrino detectors
The Daya Bay Reactor Neutrino Experiment is designed to determine precisely
the neutrino mixing angle with a sensitivity better than 0.01 in
the parameter sin at the 90% confidence level. To achieve this
goal, the collaboration will build eight functionally identical antineutrino
detectors. The first two detectors have been constructed, installed and
commissioned in Experimental Hall 1, with steady data-taking beginning
September 23, 2011. A comparison of the data collected over the subsequent
three months indicates that the detectors are functionally identical, and that
detector-related systematic uncertainties exceed requirements.Comment: 24 pages, 36 figure
New measurement of via neutron capture on hydrogen at Daya Bay
This article reports an improved independent measurement of neutrino mixing
angle at the Daya Bay Reactor Neutrino Experiment. Electron
antineutrinos were identified by inverse -decays with the emitted
neutron captured by hydrogen, yielding a data-set with principally distinct
uncertainties from that with neutrons captured by gadolinium. With the final
two of eight antineutrino detectors installed, this study used 621 days of data
including the previously reported 217-day data set with six detectors. The
dominant statistical uncertainty was reduced by 49%. Intensive studies of the
cosmogenic muon-induced Li and fast neutron backgrounds and the
neutron-capture energy selection efficiency, resulted in a reduction of the
systematic uncertainty by 26%. The deficit in the detected number of
antineutrinos at the far detectors relative to the expected number based on the
near detectors yielded in the
three-neutrino-oscillation framework. The combination of this result with the
gadolinium-capture result is also reported.Comment: 26 pages, 23 figure
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