Special study: Legal transition programme review

This study is an evaluation of the European Bank for Reconstruction and Development's Legal Transition Programme’s activities from 2001-2011, through a review of a sample of 30 legal reform projects and advisory projects in Armenia, Hungary, Mongolia, Russia and Serbia. It was conducted by the Evaluation department in conjunction with three external experts: Professor Douglas Arner (University of Hong Kong), Professor Charles Booth (University of Hawaii) and Professor Gordon Walker (LaTrobe University). Overall the programme was found to be successful due to its compatibility with the Bank’s activities and highly relevant due to its support of the Bank’s investments through contributions to legal improvements. The programme’s projects have made a core contribution to the transition process, influencing domestic policy formulation and contributing to stronger free market economies. The transition impact and sustainability of the programme was found to be excellent.published_or_final_versio

Probing and manipulating valley coherence of dark excitons in monolayer WSe2_2

Monolayers of semiconducting transition metal dichalcogenides are two-dimensional direct-gap systems which host tightly-bound excitons with an internal degree of freedom corresponding to the valley of the constituting carriers. Strong spin-orbit interaction and the resulting ordering of the spin-split subbands in the valence and conduction bands makes the lowest-lying excitons in WX$_2$ (X~being S or Se) spin-forbidden and optically dark. With polarization-resolved photoluminescence experiments performed on a WSe$_2$ monolayer encapsulated in a hexagonal boron nitride, we show how the intrinsic exchange interaction in combination with the applied in-plane and/or out-of-plane magnetic fields enables one to probe and manipulate the valley degree of freedom of the dark excitons.Comment: Manuscript: 6 pages, 3 figures; SM: 6 pages, 5 figure

Fine structure of K\mathrm{K}-excitons in multilayers of transition metal dichalcogenides

Reflectance and magneto-reflectance experiments together with theoretical modelling based on the $\mathbf{k\cdot p}$ approach have been employed to study the evolution of direct bandgap excitons in MoS$_2$ layers with a thickness ranging from mono- to trilayer. The extra excitonic resonances observed in MoS$_2$ multilayers emerge as a result of the hybridization of Bloch states of each sub-layer due to the interlayer coupling. The properties of such excitons in bi- and trilayers are classified by the symmetry of corresponding crystals. The inter- and intralayer character of the reported excitonic resonances is fingerprinted with the magneto-optical measurements: the excitonic $g$-factors of opposite sign and of different amplitude are revealed for these two types of resonances. The parameters describing the strength of the spin-orbit interaction are estimated for bi- and trilayer MoS$_2$.Comment: 14 pages, 10 figure

Neutral and charged dark excitons in monolayer WS2_2

Low temperature and polarization resolved magneto-photoluminescence experiments are used to investigate the properties of dark excitons and dark trions in a monolayer of WS$_2$ encapsulated in hexagonal BN (hBN). We find that this system is an $n$-type doped semiconductor and that dark trions dominate the emission spectrum. In line with previous studies on WSe$_2$, we identify the Coulomb exchange interaction coupled neutral dark and grey excitons through their polarization properties, while an analogous effect is not observed for dark trions. Applying the magnetic field in both perpendicular and parallel configurations with respect to the monolayer plane, we determine the g-factor of dark trions to be $g\sim$-8.6. Their decay rate is close to 0.5 ns, more than 2 orders of magnitude longer than that of bright excitons.Comment: 6 pages, 6 figures, supplemental materia

Fecal-Sac Ingestion by Spotted Towhees

Altricial nestlings encase excrement in fecal sacs that parents remove by either ingesting them or transporting them away from the nest. Ingestion may allow energetically or nutritionally deprived parents to recapture energy or nutrients that might be lost because of nestlings\u27 inefficient digestion (the parental-nutrition hypothesis ), but ingestion may also permit parents to avoid flights from the nest that interfere with parental care (e.g., brooding young; the economic-disposal hypothesis ). We used a hypothetico-deductive approach to test the two hypotheses\u27 ability to account for fecal-sac ingestion by the Spotted Towhee (Pipilo maculatus). We confirmed the parental-nutrition hypothesis\u27 predictions that more fecal sacs should be ingested in years of food shortage (males only), late in the season when food supplies decline (both sexes), by parents that had the greatest difficulty raising young (i.e., underweight young), and that adults\u27 body condition should vary directly with their rate of fecal-sac ingestion (females only). We rejected the economic-disposal hypothesis\u27 prediction of a decline in fecal-sac ingestion with increasing brood size. The latter, plus the observation that nearly 40% of males ingest fecal sacs despite their spending virtually no time attending nests, suggests that fecal-sac ingestion is not a mechanism to avoid needless and time-consuming flights from the nest that interfere with parental care. Fecal-sac ingestion by Spotted Towhees is better interpreted as either a resource supplement to parents or as a mechanism to satiate hunger so that parents can maintain rates of feeding to dependent young