Learning from 20 Years of Payments for Ecosystem Services in Costa Rica

Costa Rica's Payments for Ecosystems Services (PES) programme has become something of an icon in the world of conservation. Its innovative blend of economic and regulatory instruments - and its hitches and successes - provide a valuable source of inspiration for other countries that are looking for effective ways to conserve and regenerate ecosystems. Since 1997, nearly one million hectares of forest in Costa Rica have been part of the PES programme at one time or another, and forest cover has now returned to over 50 per cent of the country's land area, from a low of just 20 per cent in the 1980s. What lessons can be learnt from the 20 years since it was founded? Also published in Spanish, this paper is for local practitioners, international researchers and donors who are interested in the Costa Rican experience

Numerical validation of the incremental launching method of a steel bridge through a small-scale experimental study

The final publication is available at Springer via http://dx.doi.org/10.1007/s40799-016-0037-5 This article presents an experimental and a numerical study of an incremental launching process of a steel bridge. The former is deployed in a scale-reduced laboratory,whereas the latter is performed using the finite elementmethod. The numerical simulation is based upon realistic transient boundary conditions and accurately reproduces the elastic response of the steel bridge during launching. This numerical approach is validated experimentally with the scale-reduced test performed at the laboratory. The properly validated numerical model is subsequently systematically employed as a simulation tool of the process. The proposed simulation protocol might be useful for design and monitoring purposes of steel bridges to be launched. Results concerning strains, stresses, and displacements might be inferred from the model and thus compared to field measurements obtained in situ. The conditions presented at the end of the article are potentially useful for researchers and practice engineers alike

Versatile module for experiments with focussing neutron guides

We report the development of a versatile module that permits fast and reliable use of focussing neutron guides under varying scattering angles. A simple procedure for setting up the module and neutron guides is illustrated by typical intensity patterns to highlight operational aspects as well as typical parasitic artefacts. Combining a high-precision alignment table with separate housings for the neutron guides on kinematic mounts, the change-over between neutron guides with different focussing characteristics requires no readjustments of the experimental set-up. Exploiting substantial gain factors, we demonstrate the performance of this versatile neutron scattering module in a study of the effects of uniaxial stress on the domain populations in the transverse spin density wave phase of single crystal Cr

Assessing Code Authorship: The Case of the Linux Kernel

Code authorship is a key information in large-scale open source systems. Among others, it allows maintainers to assess division of work and identify key collaborators. Interestingly, open-source communities lack guidelines on how to manage authorship. This could be mitigated by setting to build an empirical body of knowledge on how authorship-related measures evolve in successful open-source communities. Towards that direction, we perform a case study on the Linux kernel. Our results show that: (a) only a small portion of developers (26 %) makes significant contributions to the code base; (b) the distribution of the number of files per author is highly skewed --- a small group of top authors (3 %) is responsible for hundreds of files, while most authors (75 %) are responsible for at most 11 files; (c) most authors (62 %) have a specialist profile; (d) authors with a high number of co-authorship connections tend to collaborate with others with less connections.Comment: Accepted at 13th International Conference on Open Source Systems (OSS). 12 page

Comparing radial velocities of atmospheric lines with radiosonde measurements

The precision of radial velocity (RV) measurements depends on the precision attained on the wavelength calibration. One of the available options is to use atmospheric lines as a natural, freely available wavelength reference. Figueira et al. measured the RV of O2 lines using High Accuracy Radial velocity Planet Searcher (HARPS) and showed that the scatter was only of ∼10 m s−1 over a time-scale of 6 yr. Using a simple but physically motivated empirical model, they demonstrated a precision of 2 m s−1, roughly twice the average photon noise contribution. In this paper, we take advantage of a unique opportunity to confirm the sensitivity of the telluric absorption lines' RV to different atmospheric and observing conditions by means of contemporaneous in situ wind measurements. This opportunity is a result of the work done during site testing and characterization for the European Extremely Large Telescope (E-ELT). The HARPS spectrograph was used to monitor telluric standards while contemporaneous atmospheric data were collected using radiosondes. We quantitatively compare the information recovered by the two independent approaches. The RV model fitting yielded results similar to that of Figueira et al., with lower wind magnitude values and varied wind direction. The probes confirmed the average low wind magnitude and suggested that the average wind direction is a function of time as well. However, these results are affected by large uncertainty bars that probably result from a complex wind structure as a function of height. The two approaches deliver the same results in what concerns wind magnitude and agree on wind direction when fitting is done in segments of a couple of hours. Statistical tests show that the model provides a good description of the data on all time-scales, being always preferable to not fitting any atmospheric variation. The smaller the time-scale on which the fitting can be performed (down to a couple of hours), the better the description of the real physical parameters is. We then conclude that the two methods deliver compatible results, down to better than 5 m s−1 and less than twice the estimated photon noise contribution on O2 lines' RV measurement. However, we cannot rule out that parameters α and γ (dependence on airmass and zero-point, respectively) have a dependence on time or exhibit some cross-talk with other parameters, an issue suggested by some of the result

New results for the missing quantum numbers labeling the quadrupole and octupole boson basis

The many $2^k$-pole boson states, $|N_kv_k\alpha_k I_kM_k>$ with $k=2,3$, realize the irreducible representation (IR) for the group reduction chains $SU(2k+1)\supset R_{2k+1}\supset R_3\supset R_2$. They have been analytically studied and widely used for the description of nuclear systems. However, no analytical expression for the degeneracy $d_v(I)$ of the $R_{2k+1}$'s IR, determined by the reduction $R_{2k+1}\supset R_3$, is available. Thus, the number of distinct values taken by $\alpha_k$ has been so far obtained by solving some complex equations. Here we derive analytical expressions for the degeneracy $d_v(I)$ characterizing the octupole and quadrupole boson states, respectively. The merit of this work consists of the fact that it completes the analytical expressions for the $2^k$-pole boson basis.Comment: 10page