Detecting collusion in timber auctions : an application to Romania

Romania was one of the first transition countries in Europe to introduce auctions for allocating standing timber (stumpage) in public forests. In comparison with the former system in the country-administrative allocation at set prices-timber auctions offer several potential advantages: greater revenue generation for the government, a higher probability that tracts will be allocated to the firms that value them most highly, and stronger incentives for technological change within industry and efficiency gains in the public sector. Competition is the key to realizing these advantages. Unfortunately, collusion among bidders often limits competition in timber auctions, including in well-established market economies such as the United States. The result is that tracts sell below their fair market value, which undermines the advantages of auctions. This paper examines the Romanian auction system, with a focus on the use of econometric methods to detect collusion. It begins by describing the historical development of the system and the principal steps in the auction process. It then discusses the qualitative impacts of various economic and institutional factors, including collusion, on winning bids in different regions of the country. This discussion draws on information from a combination of sources, including unstructured interviews conducted with government officials and company representatives during 2003. Next, the paper summarizes key findings from the broader research literature on auctions, with an emphasis on empirical studies that have developed econometric methods for detecting collusion. It then presents an application of such methods to timber auction data from two forest directorates in Romania, Neamt and Suceava. This application confirms that data from Romanian timber auctions can be used to determine the likelihood of collusion, and it suggests that collusion reduced winning bids in Suceava in 2002 and perhaps also in Neamt. The paper concludes with a discussion of actions that the government can take to reduce the incidence of collusion and minimize its impact on auction outcomes.Forestry,Wildlife Resources,Markets and Market Access,Access to Markets,Technology Industry

Valence change of praseodymium in Pr0.5Ca0.5CoO3 investigated by x-ray absorption spectroscopy

X-ray absorption spectroscopy measurements in Pr0.5Ca0.5CoO3 were performed at the Pr M4,5, Pr L3, and Ca L2,3 absorption edges as a function of temperature below 300 K. Ca spectra show no changes down to 10 K while a noticeable thermally dependent evolution takes place at the Pr edges across the metal-insulator transition. Spectral changes are analyzed by different methods, including multiple scattering simulations, which provide quantitative details on an electron loss at Pr 4f orbitals. We conclude that in the insulating phase a fraction [15(+5)%] of Pr3+ undergoes a further oxidation to adopt a hybridized configuration composed of an admixture of atomic-like 4f1 states (Pr4+) and f- symmetry states on the O 2p valence band (Pr3+L states) indicative of a strong 4f- 2p interaction.Comment: 19 pages (.doc), 4 figures, Phys. Rev. B, in pres

Nanoscale mechanical control of surface electrical properties of manganite films with magnetic nanoparticles

Mechanical control of electrical properties in complex heterostructures, consisting of magnetic FeOx nanoparticles on top of manganite films, is achieved using atomic force microscope AFM based methods. Under applied pressure of the AFM tip, drop of the electrical conductivity is observed inducing an electrically insulating state upon a critical normal load. Current and surface potential maps suggest that the switching process is mainly governed by the flexoelectric field induced at the sample surface. The relaxation process of the electrical surface potential indicates that the diffusion of oxygen vacancies from the bulk of the manganite films towards the sample surface is the dominant relaxation mechanism. The magnetic FeOx nanoparticles, staying attached to the sample surface after the rubbing, protect the underlying manganite films and provide stability of the observed resistive switching effect. The employed mechanical control gives a new freedom in the design of resistive switching devices since it does not depend on the film thickness, and biasing is not neede

Chiral surface spin textures in Cu2OSeO3 unveiled by soft X ray scattering in specular reflection geometry

Resonant elastic soft X ray magnetic scattering XRMS is a powerful tool to explore long periodic spin textures in single crystals. However, due to the limited momentum transfer range imposed by long wavelengths of photons in the soft x ray region, Bragg diffraction is restricted to crystals with the large lattice parameters. Alternatively, small angle X ray scattering has been involved in the soft energy X ray range which, however, brings in difficulties with the sample preparation that involves focused ion beam milling to thin down the crystal to below a few hundred nm thickness. We show how to circumvent these restrictions using XRMS in specular reflection from a sub nanometer smooth crystal surface. The method allows observing diffraction peaks from the helical and conical spin modulations at the surface of a Cu2OSeO3 single crystal and probing their corresponding chirality as contributions to the dichroic scattered intensity. The results suggest a promising way to carry out XRMS studies on a plethora of noncentrosymmetric systems hitherto unexplored with soft X rays due to the absence of the commensurate Bragg peaks in the available momentum transfer rang

Angular Momentum Flow During Ultrafast Demagnetization of a Ferrimagnet

One of the key processes setting the speed of the ultrafast magnetization phenomena is the angular momentum transfer from and into the spin system. However, the way the angular momentum flows during ultrafast demagnetization and magnetization switching phenomena remains elusive so far. We report on time resolved soft x ray magnetic circular dichroism measurements of the ferrimagnetic GdFeCo alloy allowing us to record the dynamics of elemental spin and orbital moments at the Fe and Gd sites during femtosecond laser induced demagnetization. We observe a complete transfer of spin and orbital angular momentum to the lattice during the first hundreds of femtoseconds of the demagnetization proces

Ultrafast and Distinct Spin Dynamics in Magnetic Alloys

Controlling magnetic order on ultrashort timescales is crucial for engineering the next-generation magnetic devices that combine ultrafast data processing with ultrahigh-density data storage. An appealing scenario in this context is the use of femtosecond (fs) laser pulses as an ultrafast, external stimulus to fully set the orientation and the magnetization magnitude of a spin ensemble. Achieving such control on ultrashort timescales, e.g., comparable to the excitation event itself, remains however a challenge due to the lack of understanding the dynamical behavior of the key parameters governing magnetism: The elemental magnetic moments and the exchange interaction. Here, we investigate the fs laser-induced spin dynamics in a variety of multi-component alloys and reveal a dissimilar dynamics of the constituent magnetic moments on ultrashort timescales. Moreover, we show that such distinct dynamics is a general phenomenon that can be exploited to engineer new magnetic media with tailor-made, optimized dynamic properties. Using phenomenological considerations, atomistic modeling and time-resolved X-ray magnetic circular dichroism (XMCD), we demonstrate demagnetization of the constituent sub-lattices on significantly different timescales that depend on their magnetic moments and the sign of the exchange interaction. These results can be used as a “recipe” for manipulation and control of magnetization dynamics in a large class of magnetic materials

Controlled Magnetic Anisotropy in Single Domain Mn-doped Biosynthesized Nanoparticles

Magnetotactic bacteria Magnetospirillum gryphiswaldense synthesize cubo-octahedral shaped magnetite nanoparticles, called magnetosomes, with a mean diameter of 40 nm. The high quality of the biosynthesized nanoparticles makes them suitable for numerous applications in fields like cancer therapy, among others. The magnetic properties of magnetite magnetosomes can be tailored by doping them with transition metal elements, increasing their potential applications. In this work, we address the effect of Mn doping on the main properties of magnetosomes by the combination of structural and magnetic characterization techniques. Energy-dispersive X-ray spectroscopy, X-ray absorption nearedge structure, and X-ray magnetic circular dichroism results reveal a Mn dopant percentage of utmost 2.3%, where Mn cations are incorporated as a combination of Mn2+ and Mn3+, preferably occupying tetrahedral and octahedral sites, respectively. Fe substitution by Mn notably alters the magnetic behavior of the doped magnetosomes. Theoretical modeling of the experimental hysteresis loops taken between 5 and 300 K with a modified Stoner-Wohlfarth approach highlights the different anisotropy contributions of the doped magnetosomes as a function of temperature. In comparison with the undoped magnetosomes, Mn incorporation alters the magnetocrystalline anisotropy introducing a negative and larger cubic anisotropy down to the Verwey transition, which appears shifted to lower temperature values as a consequence of Mn doping. On the other hand, Mn-doped magnetosomes show a decrease in the uniaxial anisotropy in the whole temperature range, most likely associated with a morphological modification of the Mn-doped magnetosomes.The Spanish and Basque Governments are acknowledged for funding under project numbers MAT2017- 83631-C3-R and IT-1245-19, respectively

Inner relaxations in equiatomic single phase high entropy cantor alloy

The superior properties of high entropy multi functional materials are strongly connected with their atomic heterogeneity through many different local atomic interactions. The detailed element specific studies on a local scale can provide insight into the primary arrangements of atoms in multicomponent systems and benefit to unravel the role of individual components in certain macroscopic properties of complex compounds. Herein, multi edge X ray absorption spectroscopy combined with reverse Monte Carlo simulations was used to explore a homogeneity of the local crystallographic ordering and specific structure relaxations of each constituent in the equiatomic single phase face centered cubic CrMnFeCoNi high entropy alloy at room temperature. Within the considered fitting approach, all five elements of the alloy were found to be distributed at the nodes of the fcc lattice without any signatures of the additional phases at the atomic scale and exhibit very close statistically averaged interatomic distances 2.54 2.55 with their nearest neighbors. Enlarged structural displacements were found solely for Cr atoms. The macroscopic magnetic properties probed by conventional magnetometry demonstrate no opening of the hysteresis loops at 5 K and illustrate a complex character of the long range magnetic order after field assisted cooling in 5 T. The observed magnetic behavior is assigned to effects related to structural relaxations of Cr. Besides, the advantages and limitations of the reverse Monte Carlo approach to studies of multicomponent systems like high entropy alloys are highlighte