Practical Lessons in Applied Resource Valuation: Evaluating Bintuni Bay

The basic objective of the study was to conduct an environmental economic analysis of the various activities taking place in the Bintuni Bay area. The Ministry of Environment was, at that time, starting to close down non-sustainable logging operations while also promoting the conservation of important natural areas. The analysis would provide insights into optimal conservation and development strategies for the resource. Such an analysis needed to be provided quickly to senior policy makers. The entire project from inception, to field work, to analysis, to input into the decision-making process via a workshop of senior policy-makers took less than one-half of one year to complete. Timely delivery of an understandable analytical product was therefore an important aspect of the study.Resource valuation

Market-based Instruments for Environmental Policymaking in Latin America and the Caribbean: Lessons from Eleven Countries

This report is a summary of country studies in Latin America and the Caribbean, addressing the use of market-based instruments (MBIs) and command-and-control (CAC) measures for environmental management in the region. Even though MBIs can significantly add efficiency to existing CAC mechanisms, the scope of MBIs should match the countries institutional capacity to implement them. Gradual and flexible reforms are likely to succeed within the current regional context of continued institutional changes. A key function of MBIs is usually revenue collection, though it does not necessarily lead to successful environmental management. The study suggests that revenues should be channeled to local authorities for an effective MBI's implementation. The report also critiques the regular practice of international donor agencies in recommending the solutions suitable for developed countries, without considering the institutional conditions in developing countries. Further, the study explores both the successes and difficulties experienced in the region regarding regulations, macro-policies, and MBIs; the institutional frameworks of the countries under review; and, the issues considered in the design of MBIs, in order to promote a beneficial dialogue among them

Quantum suppression of shot noise in atom-size metallic contacts

The transmission of conductance modes in atom-size gold contacts is investigated by simultaneously measuring conductance and shot noise. The results give unambiguous evidence that the current in the smallest gold contacts is mostly carried by nearly fully transmitted modes. In particular, for a single-atom contact the contribution of additional modes is only a few percent. In contrast, the trivalent metal aluminum does not show this property.Comment: Fig. 2 replaced, small errors correcte

Observation of electronic and atomic shell effects in gold nanowires

The formation of gold nanowires in vacuum at room temperature reveals a periodic spectrum of exceptionally stable diameters. This is identified as shell structure similar to that which was recently discovered for alkali metals at low temperatures. The gold nanowires present two competing `magic' series of stable diameters, one governed by electronic structure and the other by the atomic packing.Comment: 4 pages, 4 figure

Quantum properties of atomic-sized conductors

Using remarkably simple experimental techniques it is possible to gently break a metallic contact and thus form conducting nanowires. During the last stages of the pulling a neck-shaped wire connects the two electrodes, the diameter of which is reduced to single atom upon further stretching. For some metals it is even possible to form a chain of individual atoms in this fashion. Although the atomic structure of contacts can be quite complicated, as soon as the weakest point is reduced to just a single atom the complexity is removed. The properties of the contact are then dominantly determined by the nature of this atom. This has allowed for quantitative comparison of theory and experiment for many properties, and atomic contacts have proven to form a rich test-bed for concepts from mesoscopic physics. Properties investigated include multiple Andreev reflection, shot noise, conductance quantization, conductance fluctuations, and dynamical Coulomb blockade. In addition, pronounced quantum effects show up in the mechanical properties of the contacts, as seen in the force and cohesion energy of the nanowires. We review this reseach, which has been performed mainly during the past decade, and we discuss the results in the context of related developments.Comment: Review, 120 pages, 98 figures. In view of the file size figures have been compressed. A higher-resolution version can be found at: http://lions1.leidenuniv.nl/wwwhome/ruitenbe/review/QPASC-hr-ps-v2.zip (5.6MB zip PostScript

Observation of shell structure in sodium nanowires

The quantum states of a system of particles in a finite spatial domain in general consist of a set of discrete energy eigenvalues; these are usually grouped into bunches of degenerate or close-lying levels, called shells. In fermionic systems, this gives rise to a local minimum in the total energy when all the states of a given shell are occupied. In particular, the closed-shell electronic configuration of the noble gases produces their exceptional stability. Shell effects have previously been observed for protons and neutrons in nuclei and for clusters of metal atoms. Here we report the observation of shell effects in an open system - a sodium metal nanowire connecting two bulk sodium metal electrodes, which are progressively pulled apart. We measure oscillations in the statistical distribution of conductance values, for contact cross-sections containing up to a hundred atoms or more. The period follows the law expected from shell-closure effects, similar to the abundance peaks at `magic numbers' of atoms in metal clusters.Comment: The argumentation in favour of shell structure owing to the fluctuations in the free energy of the nanowires has been strengthened. Further improvements in the presentation include the plot of the radius of the wires versus shell number in Fig.

Effect of bonding of a CO molecule on the conductance of atomic metal wires

We have measured the effect of bonding of a CO molecule on the conductance of Au, Cu, Pt, and Ni atomic contacts at 4.2 K. When CO gas is admitted to the metal nano contacts, a conductance feature appears in the conductance histogram near 0.5 of the quantum unit of conductance, for all metals. For Au, the intensity of this fractional conductance feature can be tuned with the bias voltage, and it disappears at high bias voltage (above $\sim$ 200 mV). The bonding of CO to Au appears to be weakest, and associated with monotomic Au wire formation.Comment: 6 figure

Quantum interference effects in a system of two tunnel point-contacts in the presence of single scatterer: simulation of a double-tip STM experiment

The conductance of systems containing two tunnel point-contacts and a single subsurface scatterer is investigated theoretically. The problem is solved in the approximation of s-wave scattering giving analytical expressions for the wave functions and for the conductance of the system. Conductance oscillations resulting from the interference of electron waves passing through different contacts and their interference with the waves scattered by the defect are analyzed. The prospect for determining the depth of the impurity below the metal surface by using the dependence of the conductance as a function of the distance between the contacts is discussed. It is shown that the application of an external magnetic field results in Aharonov-Bohm type oscillations in the conductance, the period of which allows detection of the depth of the defect in a double tip STM experiment.Comment: 11 pages, 4 figures, to be published in Fiz. Nizk. Temp. (Low Temp. Phys.), V.37, No.1 (2011) corrected figure