952 research outputs found
Poverty Traps
The understanding of why some countries fail to develop is one of the most intriguing and
productive challenges for the modern theory of economic growth. Although many questions
remains unanswered, the theory has gone a long way to explain and reveal many of the
reasons underlying the persistence of poverty traps. Multiple causes, endogeneity and
country-specific differences make it difficult to explain within a unified framework why some
economies, caught in a vicious cycle, suffer from persistent underdevelopment
Electrostatic tailoring of magnetic interference in quantum point contact ballistic Josephson junctions
The magneto-electrostatic tailoring of the supercurrent in quantum point
contact ballistic Josephson junctions is demonstrated. An etched InAs-based
heterostructure is laterally contacted to superconducting niobium leads and the
existence of two etched side gates permits, in combination with the application
of a perpendicular magnetic field, to modify continuously the magnetic
interference pattern by depleting the weak link. For wider junctions the
supercurrent presents a Fraunhofer-like interference pattern with periodicity
h/2e whereas by shrinking electrostatically the weak link, the periodicity
evolves continuously to a monotonic decay. These devices represent novel
tunable structures that might lead to the study of the elusive Majorana
fermions.Comment: 4.5 pages, 4 color figure
Picocyanobacteria distribution in the Ebro Estuary (Spain)
The stratified estuary of the Ebro River is located on the Mediterranean coast of Spain. From samples obtained in 6 sampling campaigns between July 1999 and February 2000 from the last 18 km of Ebro River, the abundance of picocyanobacteria was estimated by epifluorescence microscopy. The abundance of picocyanobacteria reached 93.7 x106 cells L–1 in the river mouth (station R1) below the surface, in October 1999. In deeper layers of salt wedge area stations (near the river mouth), we could observe higher concentrations of marine cyanobacteria. This study offers comments about the abundance and distribution in cyanobacteria
On the structure of isothermal acoustic shocks under classical and artificial viscosity laws: Selected case studies
Assuming Newton's law of cooling, the propagation and structure of isothermal
acoustic shocks are studied under four different viscosity laws. Employing both
analytical and numerical methods, 1D traveling wave solutions for the velocity
and density fields are derived and analyzed. For each viscosity law considered,
expressions for both the shock thickness and the asymmetry metric are
determined. And, to ensure that isothermal flow is achievable, upper bounds on
the associated Mach number values are derived/computed using the isothermal
version of the energy equation.Comment: 26 pages, 2 figures, journal articl
Device for dispersal of micrometer- and submicrometer-sized particles in vaccum
A simple, versatile device for dispersing micrometer‐ and submicrometer-sized particles in vacuum is described. The source allows control of particle size (0.5 μm≤l≤200 μm) and particle flux density up to roughly 107 cm−2 s−1. Several types of microparticles were successfully dispersed
Giemsa-based cytological assessment of area, shape and nucleus:cytoplasm ratio of goblet cells of rabbit bulbar conjunctiva
Little-Parks effect in single YBaCuO sub-micron rings
The properties of single submicron high-temperature superconductor (HTS)
rings are investigated. The Little-Parks effect is observed and is accompanied
by an anomalous behavior of the magnetic dependence of the resistance, which we
ascribe to non-uniform vorticity (superfluid angular momentum) within the ring
arms. This effect is linked to the peculiar HTS-relationship between the values
of the coherence length and the London penetration depth.Comment: 14 pages, 3 figure
Living on the Edge: Settlement Patterns by the Symbiotic Barnacle \u3cem\u3eXenobalanus globicipitis\u3c/em\u3e on Small Cetaceans
The highly specialized coronulid barnacle Xenobalanus globicipitis attaches exclusively on cetaceans worldwide, but little is known about the factors that drive the microhabitat patterns on its hosts. We investigate this issue based on data on occurrence, abundance, distribution, orientation, and size of X. globicipitis collected from 242 striped dolphins (Stenella coeruleoalba) that were stranded along the Mediterranean coast of Spain. Barnacles exclusively infested the fins, particularly along the trailing edge. Occurrence, abundance, and density of X. globicipitis were significantly higher, and barnacles were significantly larger, on the caudal fin than on the flippers and dorsal fin. Barnacles were found more frequently and in greater numbers on the dorsal rather than ventral side of the caudal fin and on the central third of dorsal and ventral fluke surfaces. Nearly all examined individuals attached with their cirral fan oriented opposite to the fluke edge. We suggest that X. globicipitis may chemically recognize dolphins as a substratum, but fins, particularly the flukes, are passively selected because of creation of vortices that increase contact of cyprids with skin and early survival of these larvae at the corresponding sites. Cyprids could actively select the trailing edge and orient with the cirri facing the main direction of flow. Attachment on the dorsal side of the flukes is likely associated with asymmetrical oscillation of the caudal fin, and the main presence on the central segment of the flukes could be related to suitable water flow conditions generated by fluke performance for both settlement and nutrient filtration
Post Activation Potentiation of Back Squat and Trap Bar Deadlift on Acute Sprint Performance
Please refer to the pdf version of the abstract located adjacent to the title
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