Effect of Pesticide Types on Community Structure of Arthropod in Soy Crops

This study was carried out on three soybean farms located in the Liverpool Plains Shire in New South Wales, Australia. The soybean farms were different in terms of pesticide type used. One of the soy crops was sprayed with broad spectrum synthetic pesticides (synthetic pyrethroids), one site of soy crop was sprayed with natural pyrethrum - an organically certified pesticide, and one of the soy crops was not treated with any pesticides. Arthropod samples were collected on three occasions at every site except in the third site of soy crops which was not treated with any pesticides. Samplings were done using sweep nets and beat sheets. There were no significant differences of community structure change between farms treated with different pesticide regimes (F2,5= 4.2599, P(perm)= 0.188), and no significant differences in arthropod species richness. The abundance of arthropods was significantly different for site treated with biopesticide and site treated with synthetic pyrethroids (G6 = 284.36, P <0.0001), non-sprayed site and site treated with synthetic pyrethroids (G6 = 2110, P < 0.0001), and non-sprayed site to site treated with biopesticide (G6 = 2027, P < 0.0001). The use of synthetic pesticides in agriculture has been found to suppress pests and beneficial arthropods, while the use of biopesticides or without pesticide, to some extent, may let beneficials thrive in the system and also may suppress pest arthropods

Work extraction in the spin-boson model

We show that work can be extracted from a two-level system (spin) coupled to a bosonic thermal bath. This is possible due to different initial temperatures of the spin and the bath, both positive (no spin population inversion) and is realized by means of a suitable sequence of sharp pulses applied to the spin. The extracted work can be of the order of the response energy of the bath, therefore much larger than the energy of the spin. Moreover, the efficiency of extraction can be very close to its maximum, given by the Carnot bound, at the same time the overall amount of the extracted work is maximal. Therefore, we get a finite power at efficiency close to the Carnot bound. The effect comes from the backreaction of the spin on the bath, and it survives for a strongly disordered (inhomogeneously broadened) ensemble of spins. It is connected with generation of coherences during the work-extraction process, and we derived it in an exactly solvable model. All the necessary general thermodynamical relations are derived from the first principles of quantum mechanics and connections are made with processes of lasing without inversion and with quantum heat engines.Comment: 30 pages, 6 figure

Force balance and membrane shedding at the Red Blood Cell surface

During the aging of the red-blood cell, or under conditions of extreme echinocytosis, membrane is shed from the cell plasma membrane in the form of nano-vesicles. We propose that this process is the result of the self-adaptation of the membrane surface area to the elastic stress imposed by the spectrin cytoskeleton, via the local buckling of membrane under increasing cytoskeleton stiffness. This model introduces the concept of force balance as a regulatory process at the cell membrane, and quantitatively reproduces the rate of area loss in aging red-blood cells.Comment: 4 pages, 3 figure

Corrections to the universal behavior of the Coulomb-blockade peak splitting for quantum dots separated by a finite barrier

Building upon earlier work on the relation between the dimensionless interdot channel conductance g and the fractional Coulomb-blockade peak splitting f for two electrostatically equivalent dots, we calculate the leading correction that results from an interdot tunneling barrier that is not a delta-function but, rather, has a finite height V and a nonzero width xi and can be approximated as parabolic near its peak. We develop a new treatment of the problem for g much less than 1 that starts from the single-particle eigenstates for the full coupled-dot system. The finiteness of the barrier leads to a small upward shift of the f-versus-g curve at small values of g. The shift is a consequence of the fact that the tunneling matrix elements vary exponentially with the energies of the states connected. Therefore, when g is small, it can pay to tunnel to intermediate states with single-particle energies above the barrier height V. The correction to the zero-width behavior does not affect agreement with recent experimental results but may be important in future experiments.Comment: Title changed from ``Non-universal...'' to ``Corrections to the universal...'' No other changes. 10 pages, 1 RevTeX file with 2 postscript figures included using eps

Correlated charge polarization in a chain of coupled quantum dots

Coherent charge transfer in a linear array of tunnel-coupled quantum dots, electrostatically coupled to external gates, is investigated using the Bethe ansatz for a symmetrically biased Hubbard chain. Charge polarization in this correlated system is shown to proceed via two distinct processes: formation of bound states in the metallic phase, and charge transfer processes corresponding to a superposition of antibound states at opposite ends of the chain in the Mott-insulating phase. The polarizability in the insulating phase of the chain exhibits a universal scaling behavior, while the polarization charge in the metallic phase of the model is shown to be quantized in units of $e/2$.Comment: 9 pages, 3 figures, 1 tabl

The Sun's position in the sky

We express the position of the Sun in the sky as a function of time and the observer's geographic coordinates. Our method is based on applying rotation matrices to vectors describing points on the celestial sphere. We also derive direct expressions, as functions of date of the year and geographic latitude, for the duration of daylight, the maximum and minimum altitudes of the Sun, and the cardinal directions to sunrise and sunset. We discuss how to account for the eccentricity of the earth's orbit, the precessions of the equinoxes and the perihelion, the size of the solar disk, and atmospheric refraction. We illustrate these results by computing the dates of "Manhattanhenge" (when sunset aligns with the east-west streets on the main traffic grid for Manhattan, in New York City), by plotting the altitude of the Sun over representative cities as a function of time, and by showing plots ("analemmas") for the position of the Sun in the sky at a given hour of the day.Comment: 19 pages, 16 figures. v3: Replaced to match published version and to re-package Mathematica notebook as an ancillary fil

Quantum Computation with Quantum Dots

We propose a new implementation of a universal set of one- and two-qubit gates for quantum computation using the spin states of coupled single-electron quantum dots. Desired operations are effected by the gating of the tunneling barrier between neighboring dots. Several measures of the gate quality are computed within a newly derived spin master equation incorporating decoherence caused by a prototypical magnetic environment. Dot-array experiments which would provide an initial demonstration of the desired non-equilibrium spin dynamics are proposed.Comment: 12 pages, Latex, 2 ps figures. v2: 20 pages (very minor corrections, substantial expansion), submitted to Phys. Rev.

Even-odd parity effects in conductance and shot noise of metal-atomic wire-metal(superconducting) junctions

In this paper, we study the conductance and shot noise in transport through a multi-site system in a two terminal configuration. The dependence of the transport on the number of atoms in the atomic wire is investigated using a tight-binding Hamiltonian and the nonequilibrium Green's function method. In addition to reproducing the even-odd behavior in the transmission probability at the Fermi energy or the linear response conductance in the normal-atomic wire-normal metallic(NAN) junctions, we find the following: (i) The shot noise is larger in the even-numbered atomic wire than in the odd-numbered wire. (ii) The Andreev conductance displays the same even-odd parity effects in the normal-atomic wire-superconducting(NAS) junctions. In general, the conductance is higher in the odd-numbered atomic wire than in the even-numbered wire. When the number of sites ($N$) is odd and the atomic wire is mirror symmetric with respect to the center of the atomic wire, the conductance does not depend on the details of the hopping matrices in the atomic wire, but is solely determined by the coupling strength to the two leads. When $N$ is even, the conductance is sensitive to the values of the hopping matrices.Comment: 12 pages, 9 figure

Observation of Quantum Fluctuations of Charge on a Quantum Dot

We have incorporated an aluminum single electron transistor directly into the defining gate structure of a semiconductor quantum dot, permitting precise measurement of the charge in the dot. Voltage biasing a gate draws charge from a reservoir into the dot through a single point contact. The charge in the dot increases continuously for large point contact conductance and in a step-like manner in units of single electrons with the contact nearly closed. We measure the corresponding capacitance lineshapes for the full range of point contact conductances. The lineshapes are described well by perturbation theory and not by theories in which the dot charging energy is altered by the barrier conductance.Comment: Revtex, 5 pages, 3 figures, few minor corrections to the reference