Do people invest in local public goods with long-term benefits: Experimental evidence from a shanty town in Peru

This paper discusses voluntary contributions to health education in a shanty town in Peru, using a new experimental setup to identify voluntary contributions to local public goods. The experiment enables individuals to contribute to a health education meeting facilitated by an NGO, which they know will only be organised if the cumulative investment level exceeds a certain threshold value. In contrast to expectations of aid distributors, individuals contributed a substantial amount of money, despite the long-term nature of the health benefits from health education. High discount rates only seem to have had a detrimental effect on investment in a poorer subsample. Results from a complementary experiment, which identifies donations to a nutrition program, suggest that positive beliefs about short-term benefits from health education in the form of learning effects have played an important role in the investment decision. The results indicate that channelling decision-making power about public good provision to beneficiaries not necessarily implies a crowding out of investment in local public goods with long-term benefits. Hence, particular attention is given to the potential role of cash transfers in the financing of local public goods.Health education, Field Experiment, Public Good, Peru

Methods for heat transfer and temperature field analysis of the insulated diesel, phase 3

Work during Phase 3 of a program aimed at developing a comprehensive heat transfer and thermal analysis methodology for design analysis of insulated diesel engines is described. The overall program addresses all the key heat transfer issues: (1) spatially and time-resolved convective and radiative in-cylinder heat transfer, (2) steady-state conduction in the overall structure, and (3) cyclical and load/speed temperature transients in the engine structure. These are all accounted for in a coupled way together with cycle thermodynamics. This methodology was developed during Phases 1 and 2. During Phase 3, an experimental program was carried out to obtain data on heat transfer under cooled and insulated engine conditions and also to generate a database to validate the developed methodology. A single cylinder Cummins diesel engine was instrumented for instantaneous total heat flux and heat radiation measurements. Data were acquired over a wide range of operating conditions in two engine configurations. One was a cooled baseline. The other included ceramic coated components (0.050 inches plasma sprayed zirconia)-piston, head and valves. The experiments showed that the insulated engine has a smaller heat flux than the cooled one. The model predictions were found to be in very good agreement with the data

Editorial

National audienceL'éditorial explique comment ce numéro de la revue cherche à éclairer la manière dont l’agronomie, seule ou avec d’autres disciplines, peut être mise à contribution pour faire face aux multiples enjeux concernant la raréfaction des ressources naturelles qui concernent l’agriculture

Batch and median neural gas

Neural Gas (NG) constitutes a very robust clustering algorithm given euclidian data which does not suffer from the problem of local minima like simple vector quantization, or topological restrictions like the self-organizing map. Based on the cost function of NG, we introduce a batch variant of NG which shows much faster convergence and which can be interpreted as an optimization of the cost function by the Newton method. This formulation has the additional benefit that, based on the notion of the generalized median in analogy to Median SOM, a variant for non-vectorial proximity data can be introduced. We prove convergence of batch and median versions of NG, SOM, and k-means in a unified formulation, and we investigate the behavior of the algorithms in several experiments.Comment: In Special Issue after WSOM 05 Conference, 5-8 september, 2005, Pari

Spin tunneling and topological selection rules for integer spins

We present topological interference effects for the tunneling of a single large spin, which are caused by the symmetry of a general class of magnetic anisotropies. The interference originates from spin Berry phases associated with different tunneling paths exposed to the same dynamics. Introducing a generalized path integral for coherent spin states, we evaluate transition amplitudes between ground as well as low-lying excited states. We show that these interference effects lead to topological selection rules and spin-parity effects for integer spins that agree with quantum selection rules and which thus provide a generalization of the Kramers degeneracy to integer spins. Our results apply to the molecular magnets Mn12 and Fe8.Comment: 4 pages, 3 EPS figures, REVTe

Mechanisms of decoherence in weakly anisotropic molecular magnets

Decoherence mechanisms in crystals of weakly anisotropic magnetic molecules, such as V15, are studied. We show that an important decohering factor is the rapid thermal fluctuation of dipolar interactions between magnetic molecules. A model is proposed to describe the influence of this source of decoherence. Based on the exact solution of this model, we show that at relatively high temperatures, about 0.5 K, the quantum coherence in a V15 molecule is not suppressed, and, in principle, can be detected experimentally. Therefore, these molecules may be suitable prototype systems for study of physical processes taking place in quantum computers.Comment: 4 pages RevTeX, 1 figure (PostScript

SAMCO: Adaptation de la société aux risques en montagne dans un contexte de changement global

National audienceLe projet SAMCO (Society Adaptation for coping with Mountain risks in a global change COntext, 2013-2016) a pour but de développer un ensemble d'outils méthodologiques permettant d'améliorer la résilience des sociétés soumises aux impacts des risques en milieux montagneux. Ces outils visent à mesu-rer la capacité d'adaptation des écosystèmes et des sociétés à partir de l'analyse de cas réels provenant de 3 sites pilotes représentatifs

The effects of six-weeks change of direction speed and technique modification training on cutting performance and movement quality in male youth soccer players.

Cutting manoeuvres are important actions associated with soccer performance and a key action associated with non-contact anterior cruciate ligament injury; thus, training interventions that can improve cutting performance and movement quality are of great interest. The aim of this study, therefore, was to determine the effects of a six-week change of dire[ction (COD) speed and technique modification training intervention on cutting performance and movement quality in male youth soccer players (U17s, n = 8) in comparison to a control group (CG) (U18s, n = 11) who continued 'normal' training. Cutting performance was assessed based on completion time and COD deficit, and the field-based cutting movement assessment score (CMAS) qualitative screening tool was used to assess cutting movement quality. Significant main effects for time (pre-to-post changes) ( ≤ 0.041, η = 0.224-0.839) and significant interaction effects of time and group were observed for cutting completion times, COD deficits, and CMASs. Improvements in completion time ( < 0.001, = 1.63-1.90, -9% to -11% vs. -5% to 6%) and COD deficit ( ≤ 0.012, = -1.63 to -2.43, -40-52% vs. -22% to -28%) for the COD intervention group (IG) were approximately two-times greater than the CG. Furthermore, lower CMASs (i.e., improved cutting movement quality) were only observed in the IG ( ≤ 0.025, = -0.85 to -1.46, -23% to -34% vs. 6-19%) compared to the CG. The positive changes in CMASs were attributed to improved cutting technique and reduced incidences of high-risk deficits such as lateral trunk flexion, extended knee postures, knee valgus, hip internal rotation, and improved braking strategies. The results of this study indicate that COD speed and technique modification training, in addition to normal skills and strength training, improves cutting performance and movement quality in male youth soccer players. Practitioners working with male youth soccer players should implement COD speed and technique modification training to improve cutting performance and movement quality, which may decrease potential injury-risk

Spin dynamics of Mn12-acetate in the thermally-activated tunneling regime: ac-susceptibility and magnetization relaxation

In this work, we study the spin dynamics of Mn12-acetate molecules in the regime of thermally assisted tunneling. In particular, we describe the system in the presence of a strong transverse magnetic field. Similar to recent experiments, the relaxation time/rate is found to display a series of resonances; their Lorentzian shape is found to stem from the tunneling. The dynamic susceptibility $\chi(w)$ is calculated starting from the microscopic Hamiltonian and the resonant structure manifests itself also in $\chi(w)$. Similar to recent results reported on another molecular magnet, Fe8, we find oscillations of the relaxation rate as a function of the transverse magnetic field when the field is directed along a hard axis of the molecules. This phenomenon is attributed to the interference of the geometrical or Berry phase. We propose susceptibility experiments to be carried out for strong transverse magnetic fields to study of these oscillations and for a better resolution of the sharp satellite peaks in the relaxation rates.Comment: 22 pages, 23 figures; submitted to Phys. Rev. B; citations/references adde