381 research outputs found
An Investigation of a Hypothetical Medical Screening Program
This paper addresses the question what are the key parameters that determine the cost and effectiveness of a medical screening program intended to discover occult cases of a disease. The cost of the program will simply be the dollar value of the resources it uses annually. The effectiveness of the program will be measured by the mortality rate owing to a disease. The lower the mortality, the more effective we will consider the program
Seward's Folly, Salmon Management and Discounting Rates
Some months ago, the ecology project gave a series of two IIASA colloquia on some of the approaches to the salmon case study. Part of the presentations dealt with optimization of various components of the salmon system. These optimizations were done using stochastic dynamic programming. Some members of the audience expressed concern over the fact that we had used no discounting. Carl Walters explained that we did this because the management agencies are charged with management in perpetuity and therefore any sort of discounting seems a bit inappropriate. Some recent work has shown that optimal management practice of fisheries is seriously affected by discounting rates. The standard example in extremis of this problem has to do with any renewable resource
Genetic algorithm for biobjective urban transit routing problem
This paper considers solving a biobjective urban transit routing problem with a genetic algorithm approach. The objectives are to
minimize the passengers’ and operators’ costs where the quality of the route sets is evaluated by a set of parameters. The proposed
algorithm employs an adding-node procedure which helps in converting an infeasible solution to a feasible solution. A simple
yet effective route crossover operator is proposed by utilizing a set of feasibility criteria to reduce the possibility of producing an
infeasible network. The computational results from Mandl’s benchmark problems are compared with other published results in the
literature and the computational experiments show that the proposed algorithm performs better than the previous best published
results in most cases
B-L-violating Masses in Softly Broken Supersymmetry
We prove a general low-energy theorem establishing a generic relation between
the neutrino Majorana mass and the superpartner sneutrino B-L-violating
"Majorana"-like mass term. The theorem states that, if one of these two
quantities is non-zero the other one is also non-zero and, vice versa, if one
of them vanishes the other vanishes, too. The theorem is a consequence of the
underlying supersymmetry (SUSY) and valid for any realistic gauge model with
weak scale softly broken SUSY.Comment: 7 pages, Latex, 1 Postscript figur
Creating ownership:Strengths and tensions in co-production with children, young people, and adults across contexts
The inclusion of young people in conducting research leads to the creation of shared knowledge, honest communication, and increases the legitimacy of the research, allowing it to be an effective base for policy creation. This paper looks at the role of horizontal co-production with young people, as we reflect together on the process of collaboration in peace-building research
Remarks on the forces generated by two-neutrino exchange
A brief up-to-date review of the long range forces generated by two neutrino
exchange is presented. The potential due to exchange of a massive
neutrino-antineutrino pair between particles carrying weak charge might be
larger than expected if the neutrinos have not only masses but also magnetic
moments close to the present experimental bounds. It still remains too small to
be observable.Comment: 10 pages, 3 figures. One figure added. Accepted for publication in
EPJ
High scale mixing unification and large neutrino mixing angles
Starting with the hypothesis that quark and lepton mixings are identical at
or near the GUT scale, we show that the large solar and atmospheric neutrino
mixing angles together with the small reactor angle can be understood
purely as a result of renormalization group evolution. The only requirements
are that the three neutrinos must be quasi degenerate in mass and have same CP
parity. It predicts that the common Majorana mass for the neutrinos must be
larger than 0.1 eV making the idea testable in the currently planned or ongoing
experiments searching for neutrinoless-double-beta decay.Comment: 10 pages, eight figure, two tables; new material added; results
remain unchange
Correlated Hybrid Fluctuations from Inflation with Thermal Dissipation
We investigate the primordial scalar perturbations in the thermal dissipative
inflation where the radiation component (thermal bath) persists and the density
fluctuations are thermally originated. The perturbation generated in this model
is hybrid, i.e. it consists of both adiabatic and isocurvature components. We
calculate the fractional power ratio () and the correlation coefficient
() between the adiabatic and the isocurvature perturbations at the
commencing of the radiation regime. Since the adiabatic/isocurvature
decomposition of hybrid perturbations generally is gauge-dependent at
super-horizon scales when there is substantial energy exchange between the
inflaton and the thermal bath, we carefully perform a proper decomposition of
the perturbations. We find that the adiabatic and the isocurvature
perturbations are correlated, even though the fluctuations of the radiation
component is considered uncorrelated with that of the inflaton. We also show
that both and depend mainly on the ratio between the
dissipation coefficient and the Hubble parameter during inflation.
The correlation is positive () for strong dissipation cases
where , and is negative for weak dissipation instances where
. Moreover, and in this model are not
independent of each other. The predicted relation between and
is consistent with the WMAP observation. Other testable predictions are also
discussed.Comment: 18 pages using revtex4, accepted for publication in PR
Second-order corrections to noncommutative spacetime inflation
We investigate how the uncertainty of noncommutative spacetime affects on
inflation. For this purpose, the noncommutative parameter is taken to
be a zeroth order slow-roll parameter. We calculate the noncommutative power
spectrum up to second order using the slow-roll expansion. We find corrections
arisen from a change of the pivot scale and the presence of a variable
noncommutative parameter, when comparing with the commutative power spectrum.
The power-law inflation is chosen to obtain explicit forms for the power
spectrum, spectral index, and running spectral index. In cases of the power
spectrum and spectral index, the noncommutative effect of higher-order
corrections compensates for a loss of higher-order corrections in the
commutative case. However, for the running spectral index, all higher-order
corrections to the commutative case always provide negative spectral indexes,
which could explain the recent WMAP data.Comment: 15 pages, no figure, version published in PR
Second-order corrections to slow-roll inflation in the brane cosmology
We calculate the power spectrum, spectral index, and running spectral index
for the RS-II brane inflation in the high-energy regime using the slow-roll
expansion. There exist several modifications. As an example, we take the
power-law inflation by choosing an inverse power-law potential. When comparing
these with those arisen in the standard inflation, we find that the power
spectrum is enhanced and the spectral index is suppressed, while the running
spectral index becomes zero as in the standard inflation. However, since
second-order corrections are rather small, these could not play a role of
distinguishing between standard and brane inflations.Comment: 6 page
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