15,659 research outputs found
Bio-medical flow sensor
A bio-medical flow sensor including a packageable unit of a bottle, tubing and hypodermic needle which can be pre-sterilized and is disposable. The tubing has spaced apart tubular metal segments. The temperature of the metal segments and fluid flow therein is sensed by thermistors and at a downstream location heat is input by a resistor to the metal segment by a control electronics. The fluids flow and the electrical power required for the resisto to maintain a constant temperature differential between the tubular metal segments is a measurable function of fluid flow through the tubing. The differential temperature measurement is made in a control electronics and also can be used to control a flow control valve or pump on the tubing to maintain a constant flow in the tubing and to shut off the tubing when air is present in the tubing
Electrophotolysis oxidation system for measurement of organic concentration in water
Methods and apparatus for determining organic carbon in aqueous solution are described. The method comprises subjecting the aqueous solution to electrolysis, for generating oxygen from water, and simultaneously to ultraviolet radiation, for oxidation of substantially all organic carbon to carbon dioxide. The carbon dioxide is measured and the value is related to the concentration of organic carbon in the aqueous solution
Building financial institutions in developing countries
Financial development and financial institution building are important prerequisites for economic growth. However, both the potential and the problems of institution building are still vastly underestimated by those who design and fund institution building projects. The paper first underlines the importance of financial development for economic growth, then describes the main elements of “serious” institution building: the lending technology, the methodological approaches, and the question of internal structure and corporate governance. Finally, it discusses three problems which institution building efforts have to cope with: inappropriate expectations on the part of donor and partner institutions regarding the problems and effects of institution building efforts, the lack of awareness of the importance of governance and ownership issues, and financial regulation that is too restrictive for microfinance operations. All three problems together explain why there are so few successful micro and small business institutions operating worldwide
High-spin low-spin transition
Temperature dependent nuclear inelastic-scattering (NIS) of synchrotron
radiation was applied to investigate both spin states of the spin-crossover
complex [Fe(tpa)(NCS)(2)] (tpa = tris(2-pyridylmethyl)amine). A remarkable
increase of the iron-ligand bond stretching upon spin crossover has
unambiguously been identified by comparing the measured NIS spectra with
theoretical simulations based on density-functional calculations
Side-jumps in the spin-Hall effect: construction of the Boltzmann collision integral
We present a systematic derivation of the side-jump contribution to the
spin-Hall current in systems without band structure spin-orbit interactions,
focusing on the construction of the collision integral for the Boltzmann
equation. Starting from the quantum Liouville equation for the density operator
we derive an equation describing the dynamics of the density matrix in the
first Born approximation and to first order in the driving electric field.
Elastic scattering requires conservation of the total energy, including the
spin-orbit interaction energy with the electric field: this results in a first
correction to the customary collision integral found in the Born approximation.
A second correction is due to the change in the carrier position during
collisions. It stems from the part of the density matrix off-diagonal in wave
vector. The two corrections to the collision integral add up and are
responsible for the total side-jump contribution to the spin-Hall current. The
spin-orbit-induced correction to the velocity operator also contains terms
diagonal and off-diagonal in momentum space, which together involve the total
force acting on the system. This force is explicitly shown to vanish (on the
average) in the steady state: thus the total contribution to the spin-Hall
current due to the additional terms in the velocity operator is zero.Comment: Added references, expanded discussion, revised introductio
Anomalous Rashba spin splitting in two-dimensional hole systems
It has long been assumed that the inversion asymmetry-induced Rashba spin
splitting in two-dimensional (2D) systems at zero magnetic field is
proportional to the electric field that characterizes the inversion asymmetry
of the confining potential. Here we demonstrate, both theoretically and
experimentally, that 2D heavy hole systems in accumulation layer-like single
heterostructures show the opposite behavior, i.e., a decreasing, but nonzero
electric field results in an increasing Rashba coefficient.Comment: 4 pages, 3 figure
- …