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

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 $U_{e3}$ 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 ($S$) and the correlation coefficient ($\cos\Delta$) 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 $S$ and $\cos \Delta$ depend mainly on the ratio between the dissipation coefficient $\Gamma$ and the Hubble parameter $H$ during inflation. The correlation is positive ($\cos\Delta > 0$) for strong dissipation cases where $\Gamma/H >0.2$, and is negative for weak dissipation instances where $\Gamma/H <0.2$. Moreover, $S$ and $\cos \Delta$ in this model are not independent of each other. The predicted relation between $S$ and $\cos\Delta$ 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 $\mu_0$ 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

Free-H2 deoxygenation of Jatropha curcas oil into cleaner diesel-grade biofuel over coconut residue-derived activated carbon catalyst

Diesel-like hydrocarbons were produced by the catalytic deoxygenation (DO) of Jatropha curcas oil (JCO) over novel Agx/AC and Niy-Agx/AC catalysts under an H2-free atmosphere. The AC was synthesized from coconut fibre residues (CFR), where CFR is the by-product from coconut milk extraction and is particularly rich in soft fibres with high mineral content. The Niy-Agx/AC catalyst afforded higher DO activity via the decarboxylation/decarbonylation (deCOx) route than Agx/AC due to the properties of Ni, synergistic interaction of Ni and Ag species, adequate amount of strong acid sites and large number of weak acid sites, which cause extensive C-O cleavage and lead to rich formation of n-(C15+C17) hydrocarbons. The effect of Ag and Ni content were studied within the 5 to 15 wt% range. An optimum Ni and Ag metal content (5 wt%) for deCOx reaction was observed. Excess Ni is not preferable due to a tendency for cracking and Ag-rich containing catalyst weakly enforced triglycerides breaking. The Ni5-Ag5/AC govern exclusively decarbonylation reaction, which corroborates the presence of Ni²⁺ species and a high amount of strong acid sites. Ultimately, Ni5-Ag5/AC in the present study shows excellent chemical stability with consistent five reusability without drastic reduction of hydrocarbon yield (78–95%) and n-(C15+C17) selectivity (82–83%), which indicate favourable application in JCO DO