Excitation spectra of a 3He impurity on 4He clusters

The diffusion Monte Carlo technique is used to calculate and analyze the excitation spectrum of a single 3He atom bound to a cluster with N 4He atoms, with the aim of establishing the most adequate filling ordering of single-fermion orbits to the mixed clusters with a large number of 3He atoms. The resulting ordering looks like the rotational spectrum of a diatomic molecule, being classified only by the angular momentum of the level, although vibrational-like excitations appear at higher energies for sufficiently large N

Cooperation and profit allocation in distribution chains

We study the coordination of actions and the allocation of profit in distribution chains under decentralized control. We consider distribution chains in which a single supplier supplies goods for replenishment of stocks of several retailers who, in turn, sell these goods to their own separate markets. The goal of the supplier and the retailers is to maximize their individual profits. Since the optimal joint profit under centralized control is larger than the sum of the individual optimal profits under decentralized control, cooperation among firms by means of coordination of actions may improve individual profits. The effects of cooperation are studied by means of cooperative games. For each distribution chain we define a corresponding cooperative game and study its properties. Among others we show that such games are balanced. Based on the nice core structure a stable solution concept for these games is proposed and its properties are interpreted in terms of the underlying distribution chain. \u

The spectra of mixed 3^3He-4^4He droplets

The diffusion Monte Carlo technique is used to calculate and analyze the excitation spectrum of $^3$He atoms bound to a cluster of $^4$He atoms, by using a previously determined optimum filling of single-fermion orbits with well defined orbital angular momentum $L$, spin $S$ and parity quantum numbers. The study concentrates on the energies and shapes of the three kinds of states for which the fermionic part of the wave function is a single Slater determinant: maximum $L$ or maximum $S$ states within a given orbit, and fully polarized clusters. The picture that emerges is that of systems with strong shell effects whose binding and excitation energies are essentially determined over configuration at fixed number of particles and spin, i.e., by the monopole properties of an effective Hamiltonian.Comment: 14 pages, 15 figure

Translationally invariant treatment of pair correlations in nuclei: II. Tensor correlations

We study the extension of our translationally invariant treatment of few-body nuclear systems to include tensor forces and correlations. It is shown that a direct application of our method is not as successful for realistic V6 interactions as our previous results for V4 potentials suggested. We investigate the cause in detail for the case of $^4$He, and show that a combination of our method with that of Jastrow-correlated wave functions seems to be a lot more powerful, thereby suggesting that for mildly to strongly repulsive forces such a hybrid procedure may be an appropriate description.Comment: 19 pages, 3 ps figures. uses elsart, graphicx, amssym

Performance and ownership in the governance of urban water

In this paper the differences in terms of performance between public and the private governance in urban water management are investigated. A statistical ranking is implemented to determine programmatic efficiency differences in DEA, using an incomplete panel data that gathers information on 20 water utilities in Andalusia, in Southern Spain. In the model, labour and operational costs are considered as inputs. The volume of revenue water, the number of connections and the network length are used as outputs. The analysis indicates that private management is more efficient. The efficiency indicators adjusted by a variable related to quality are estimated and demonstrate that privatization of the service does not mean any loss in terms of quality. However, there are no significant differences between both types of management including as a desirable input hydraulic yield as a proxy of the degree of network renovation. A lower hydraulic efficiency in private management would suggest that the need to make significant investments could be an important factor when making the decision to privatize the management of the urban water service: Water supply; Management; Local government;

Career and Technical Education in Michigan

High school career and technical education (CTE) programs have emerged as a popular strategy for improving young people’s chances of finding – and keeping – stable jobs. Taught by former industry professionals and structured around hands-on projects, CTE aims to equip students with knowledge and skills to thrive in the workforce. Despite this wealth of attention, we know relatively little about the efficacy of CTE programs. Stakeholders like parents, students, state and local administrators all have a vested interest in better understanding the predictors and outcomes of CTE participation. This brief aims to begin that conversation by shedding light on access to and enrollment in Michigan’s high school CTE programs

Career and Technical Education in Michigan

High school career and technical education (CTE) programs have emerged as a popular strategy for improving young people’s chances of finding – and keeping – stable jobs. Taught by former industry professionals and structured around hands-on projects, CTE aims to equip students with knowledge and skills to thrive in the workforce. Despite this wealth of attention, we know relatively little about the efficacy of CTE programs. Stakeholders like parents, students, state and local administrators all have a vested interest in better understanding the predictors and outcomes of CTE participation. This brief aims to begin that conversation by shedding light on access to and enrollment in Michigan’s high school CTE programs.https://scholarworks.gsu.edu/gpl_reports/1030/thumbnail.jp

Ca impurity in small mixed 4^4He-3^3He clusters

The structure of small mixed helium clusters doped with one calcium atom has been determined within the diffusion Monte Carlo framework. The results show that the calcium atom sits at the $^4$He-$^3$He interface. This is in agreement with previous studies, both experimental and theoretical, performed for large clusters. A comparison between the results obtained for the largest cluster we have considered for each isotope shows a clear tendency of the Ca atom to reside in a deep dimple at the surface of the cluster for $^4$He clusters, and to become fully solvated for $^3$He clusters. We have calculated the absorption spectrum of Ca around the $4s4p \leftarrow 4s^2$ transition and have found that it is blue-shifted from that of the free-atom transition by an amount that depends on the size and composition of the cluster.Comment: 24 pages, 11 figures. Accepted on Journal of Chemical Physic

Equation of state of low--density neutron matter and the 1S0^1S_0 pairing gap

We report results of the equation of state of neutron matter in the low--density regime, where the Fermi wave vector ranges from $0.4 fm^{-1} \leq k_F \leq 1.0 fm^{-1}$. Neutron matter in this regime is superfluid because of the strong and attractive interaction in the $^1S_0$ channel. The properties of this superfluid matter are calculated starting from a realistic Hamiltonian that contains modern two-- and three--body interactions. The ground state energy and the $^1S_0$ superfluid energy gap are calculated using the Auxiliary Field Diffusion Monte Carlo method. We study the structure of the ground state by looking at pair distribution functions as well as the Cooper-pair wave function used in the calculations.Comment: 12 pages, 7 figure