1,183 research outputs found
Extremal transmission at the Dirac point of a photonic band structure
We calculate the effect of a Dirac point (a conical singularity in the band
structure) on the transmission of monochromatic radiation through a photonic
crystal. The transmission as a function of frequency has an extremum at the
Dirac point, depending on the transparencies of the interfaces with free space.
The extremal transmission is inversely proportional to
the longitudinal dimension of the crystal (for larger than the lattice
constant and smaller than the transverse dimension ). The interface
transparencies affect the proportionality constant , and they
determine whether the extremum is a minimum or a maximum, but they do not
affect the ``pseudo-diffusive'' 1/L dependence of .Comment: 6 pages, 4 figures. Fig. 1 revised, Fig. 4 adde
Experiments feeding butter-milk
The objects of the following feeding trials were to determine the relative values of wash water from the creamery churn, of buttermilk fed alone, and in conjunction with soaked corn, and to determine the effect of corn following a long period of feeding with a very narrow ratio.
Each lot was given all the diluted milk that it would drink. The total solids of this milk amounted to 4.5 per cent, being about one-half the total solids in ordinary buttermilk, showing that the milk was reduced about one-half its value. Lot two was fed ,two pounds of shelled corn, soaked, per day and head. Lot three was fed four pounds of shelled corn, soaked, per day and head. Lot four was fed all the corn they would eat which was from six to seven pounds per day and head. The result for lot one shows that the so-called wash water is not a sustaining ration. The pigs losing a little rising one-half pound of live weight per day and head. A part of this loss can be accounted for in stomach contents
Inelastic cotunneling in quantum dots and molecules with weakly broken degeneracies
We calculate the nonlinear cotunneling conductance through interacting
quantum dot systems in the deep Coulomb blockade regime using a rate equation
approach based on the T-matrix formalism, which shows in the concerned regions
very good agreement with a generalized master equation approach. Our focus is
on inelastic cotunneling in systems with weakly broken degeneracies, such as
complex quantum dots or molecules. We find for these systems a characteristic
gate dependence of the non-equilibrium cotunneling conductance. While on one
side of a Coulomb diamond the conductance decreases after the inelastic
cotunneling threshold towards its saturation value, on the other side it
increases monotonously even after the threshold. We show that this behavior
originates from an asymmetric gate voltage dependence of the effective
cotunneling amplitudes.Comment: 12 pages, 12 figures; revised published versio
Thermoelectric effects in Kondo correlated quantum dots
In this Letter we study thermoelectric effects in ultra small quantum dots.
We study the behaviour of the thermopower, Peltier coefficient and thermal
conductance both in the sequencial tunneling regime and in the regime where
Kondo correlations develope. Both cases of linear response and non-equilibrium
induced by strong temperature gradients are considered. The thermopower is a
very sensitive tool to detect Kondo correlations. It changes sign both as a
function of temperature and temperature gradient. We also discuss violations of
the Wiedemann-Franz law.Comment: 7 pages; 5 figure
Charge transport through weakly open one dimensional quantum wires
We consider resonant transmission through a finite-length quantum wire
connected to leads via finite transparency junctions. The coherent electron
transport is strongly modified by the Coulomb interaction. The low-temperature
current-voltage () curves show step-like dependence on the bias voltage
determined by the distance between the quantum levels inside the conductor, the
pattern being dependent on the ratio between the charging energy and level
spacing. If the system is tuned close to the resonance condition by the gate
voltage, the low-voltage curve is Ohmic. At large Coulomb energy and low
temperatures, the conductance is temperature-independent for any relationship
between temperature, level spacing, and coupling between the wire and the
leads
Cotunneling-mediated transport through excited states in the Coulomb blockade regime
We present finite bias transport measurements on a few-electron quantum dot.
In the Coulomb blockade regime, strong signatures of inelastic cotunneling
occur which can directly be assigned to excited states observed in the
non-blockaded regime. In addition, we observe structures related to sequential
tunneling through the dot, occuring after it has been excited by an inelastic
cotunneling process. We explain our findings using transport calculations
within the real-time Green's function approach, including diagrams up to fourth
order in the tunneling matrix elements.Comment: 4 pages, 3 figure
Shall Be Bright at Last: Reflections on Suffering and Hope in the Letters of Paul
These nine essays on suffering offer exercises in Christian hope. The contributors reveal honest and tender wounds of the many harsh realities of life in a broken world awaiting full redemption. They meditate on Paul\u27s holy words that teach us to pray with expectation and live by faith. They encourage fellow pilgrims to trust the path and stick together.
Shall Be Bright at Last is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.
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