Irrigation and fertigation effects on phosphorus and potassium nutrition of wine grapes

The optimal rate of irrigation of the three wine grapes Sauvignon blanc, Merlot, and Cabernet Sauvignon, grown in a semi-arid environment in Israel, was investigated during 1992 - 1998, The drip irrigation I ate was gradually raised after bud break up to a level of either 0.3, 0.4 or 0.5 Pan A coefficient, and then these coefficients vi ere maintained throughout the rest of the growing season. In an additional experiment the effects of secondary purified recycled effluent and fresh water irrigation was compared in Merlot and Cabernet Sauvignon, irrigated by surface and sub-surface drippers. The nutritional status of the vineyard was followed by leaf petiole and leaf blade analyses carried out at flowering and at harvest. Leaf petiole and blade analyses indicated that the nitrogen status of the vines was adequate. The tissue potassium level in the young vineyard was luxurious (ca, 2-3 % in petiole at harvest), reflecting an abundant supply of It by the soil, while the tissue concentration of P was at a deficient level (ca, 0.1 % and less in blades at harvest). Potassium levels declined as the vines matured, probably as a result of K depletion from the limited soil volume explored by the root system under drip irrigation. Low rates of annual phosphate fertigation (5.6-13.7 kg ha-1 P) raised tissue-P proportionally to the rate of fertigation, Irrigation according to a Pan A coefficient of 0.3, as compared to coefficients of 0.4 and 0.5, significantly reduced tissue-K levels. Irrigation with recycled water (high in NPK) raised tissue-P significantly, The relative depletion of K and P in leaf petioles and blades, from flowering to harvest, was found to be a good indicator of the nutritional status of these two elements. At flowering petiole-P was polynomially and linearly correlated with petiole- and blade-P at harvest, respectively, under a wide range of P nutritional intensities. Leaf blades at flowering and harvest had higher priority for P under low intensity of P nutrition. Suboptimal P nutrition could be diagnosed best by petiole-P concentration at harvest. The inflection petiole concentration associated with optimum P nutrition was 0.413 % P at flowering, which corresponded to 0.133 % P in petiole and blade at harvest time

Spectral Properties of Three Dimensional Layered Quantum Hall Systems

We investigate the spectral statistics of a network model for a three dimensional layered quantum Hall system numerically. The scaling of the quantity $J_0={1/2}$ is used to determine the critical exponent $\nu$ for several interlayer coupling strengths. Furthermore, we determine the level spacing distribution $P(s)$ as well as the spectral compressibility $\chi$ at criticality. We show that the tail of $P(s)$ decays as $\exp(-\kappa s)$ with $\kappa=1/(2\chi)$ and also numerically verify the equation $\chi=(d-D_2)/(2d)$, where $D_2$ is the correlation dimension and $d=3$ the spatial dimension.Comment: 4 pages, 5 figures submitted to J. Phys. Soc. Jp

First order transition from correlated electron semiconductor to ferromagnetic metal in single crystalline FeSi1-xGex

The phase diagram of FeSi1-xGex, obtained from magnetic, thermal and transport measurements on single crystals, shows a first-order transition from a correlated electron semiconductor to a ferromagnetic metal at a critical concentration, x ~ 0.25. The gap of the insulating phase strongly decreases with x. The specific heat coefficient appears to track the density of states of a Kondo insulator. The phase diagram is consistent with a correlation induced insulator-metal transition in conjunction with disorder on the Si/Ge ligand site

Targeting the CBM complex causes Treg cells to prime tumours for immune checkpoint therapy.

Solid tumours are infiltrated by effector T cells with the potential to control or reject them, as well as by regulatory T (Treg) cells that restrict the function of effector T cells and thereby promote tumour growth1. The anti-tumour activity of effector T cells can be therapeutically unleashed, and is now being exploited for the treatment of some forms of human cancer. However, weak tumour-associated inflammatory responses and the immune-suppressive function of Treg cells remain major hurdles to broader effectiveness of tumour immunotherapy2. Here we show that, after disruption of the CARMA1-BCL10-MALT1 (CBM) signalosome complex, most tumour-infiltrating Treg cells produce IFNγ, resulting in stunted tumour growth. Notably, genetic deletion of both or even just one allele of CARMA1 (also known as Card11) in only a fraction of Treg cells-which avoided systemic autoimmunity-was sufficient to produce this anti-tumour effect, showing that it is not the mere loss of suppressive function but the gain of effector activity by Treg cells that initiates tumour control. The production of IFNγ by Treg cells was accompanied by activation of macrophages and upregulation of class I molecules of the major histocompatibility complex on tumour cells. However, tumour cells also upregulated the expression of PD-L1, which indicates activation of adaptive immune resistance3. Consequently, blockade of PD-1 together with CARMA1 deletion caused rejection of tumours that otherwise do not respond to anti-PD-1 monotherapy. This effect was reproduced by pharmacological inhibition of the CBM protein MALT1. Our results demonstrate that partial disruption of the CBM complex and induction of IFNγ secretion in the preferentially self-reactive Treg cell pool does not cause systemic autoimmunity but is sufficient to prime the tumour environment for successful immune checkpoint therapy

Quantum Hall Effect in Three Dimensional Layered Systems

Using a mapping of a layered three-dimensional system with significant inter-layer tunneling onto a spin-Hamiltonian, the phase diagram in the strong magnetic field limit is obtained in the semi-classical approximation. This phase diagram, which exhibit a metallic phase for a finite range of energies and magnetic fields, and the calculated associated critical exponent, $\nu=4/3$, agree excellently with existing numerical calculations. The implication of this work for the quantum Hall effect in three dimensions is discussed.Comment: 4 pages + 4 figure

Numerical Study Comparing RANS and LES Approaches on a Circulation Control Airfoil

A numerical study over a nominally two-dimensional circulation control airfoil is performed using a large-eddy simulation code and two Reynolds-averaged Navier-Stokes codes. Different Coanda jet blowing conditions are investigated. In addition to investigating the influence of grid density, a comparison is made between incompressible and compressible flow solvers. The incompressible equations are found to yield negligible differences from the compressible equations up to at least a jet exit Mach number of 0.64. The effects of different turbulence models are also studied. Models that do not account for streamline curvature effects tend to predict jet separation from the Coanda surface too late, and can produce non-physical solutions at high blowing rates. Three different turbulence models that account for streamline curvature are compared with each other and with large eddy simulation solutions. All three models are found to predict the Coanda jet separation location reasonably well, but one of the models predicts specific flow field details near the Coanda surface prior to separation much better than the other two. All Reynolds-averaged Navier-Stokes computations produce higher circulation than large eddy simulation computations, with different stagnation point location and greater flow acceleration around the nose onto the upper surface. The precise reasons for the higher circulation are not clear, although it is not solely a function of predicting the jet separation location correctly

Nonlinear effects in microwave photoconductivity of two-dimensional electron systems

We present a model for microwave photoconductivity of two-dimensional electron systems in a magnetic field which describes the effects of strong microwave and steady-state electric fields. Using this model, we derive an analytical formula for the photoconductivity associated with photon- and multi-photon-assisted impurity scattering as a function of the frequency and power of microwave radiation. According to the developed model, the microwave conductivity is an oscillatory function of the frequency of microwave radiation and the cyclotron frequency which turns zero at the cyclotron resonance and its harmonics. It exhibits maxima and minima (with absolute negative conductivity) at the microwave frequencies somewhat different from the resonant frequencies. The calculated power dependence of the amplitude of the microwave photoconductivity oscillations exhibits pronounced sublinear behavior similar to a logarithmic function. The height of the microwave photoconductivity maxima and the depth of its minima are nonmonotonic functions of the electric field. It is pointed to the possibility of a strong widening of the maxima and minima due to a strong sensitivity of their parameters on the electric field and the presence of strong long-range electric-field fluctuations. The obtained dependences are consistent with the results of the experimental observations.Comment: 9 pages, 6 figures Labeling of the curves in Fig.3 correcte

Second Generation of Composite Fermions in the Hamiltonian Theory

In the framework of a recently developed model of interacting composite fermions restricted to a single level, we calculate the activation gaps of a second generation of spin-polarized composite fermions. These composite particles consist each of a composite fermion of the first generation and a vortex-like excitation and may be responsible for the recently observed fractional quantum Hall states at unusual filling factors such as nu=4/11,5/13,5/17, and 6/17. Because the gaps of composite fermions of the second generation are found to be more than one order of magnitude smaller than those of the first generation, these states are less visible than the usual states observed at filling factors nu=p/(2ps+1). Their stability is discussed in the context of a pseudopotential expansion of the composite-fermion interaction potential.Comment: 5 pages, 3 figures; after publication in PRB, we have realized that a factor was missing in one of the expressions; the erroneous results are now corrected; an erratum has been sent to PR

Strong localization of electrons in quasi-one-dimensional conductors

We report on the experimental study of electron transport in sub-micron-wide ''wires'' fabricated from Si $\delta$-doped GaAs. These quasi-one-dimensional (Q1D) conductors demonstrate the crossover from weak to strong localization with decreasing the temperature. On the insulating side of the crossover, the resistance has been measured as a function of temperature, magnetic field, and applied voltage for different values of the electron concentration, which was varied by applying the gate voltage. The activation temperature dependence of the resistance has been observed with the activation energy close to the mean energy spacing of electron states within the localization domain. The study of non-linearity of the current-voltage characteristics provides information on the distance between the critical hops which govern the resistance of Q1D conductors in the strong localization (SL) regime. We observe the exponentially strong negative magnetoresistance; this orbital magnetoresistance is due to the universal magnetic-field dependence of the localization length in Q1D conductors. The method of measuring of the single-particle density of states (DoS) in the SL regime has been suggested. Our data indicate that there is a minimum of DoS at the Fermi level due to the long-range Coulomb interaction.Comment: 12 pages, 11 figures; the final version to appear in Phys. Rev.

Chromosomes. CENP-C reshapes and stabilizes CENP-A nucleosomes at the centromere

Inheritance of each chromosome depends upon its centromere. A histone H3 variant, centromere protein A (CENP-A), is essential for epigenetically marking centromere location. We find that CENP-A is quantitatively retained at the centromere upon which it is initially assembled. CENP-C binds to CENP-A nucleosomes and is a prime candidate to stabilize centromeric chromatin. Using purified components, we find that CENP-C reshapes the octameric histone core of CENP-A nucleosomes, rigidifies both surface and internal nucleosome structure, and modulates terminal DNA to match the loose wrap that is found on native CENP-A nucleosomes at functional human centromeres. Thus, CENP-C affects nucleosome shape and dynamics in a manner analogous to allosteric regulation of enzymes. CENP-C depletion leads to rapid removal of CENP-A from centromeres, indicating their collaboration in maintaining centromere identity.NIH grants: (GM082989, CA186430, GM008275, GM008216, GM007229); American Heart Association predoctoral fellowship; American Cancer Society postdoctoral fellowship; NSF grant: (agreement DMR-0944772)