Auxins and cytokinins : the role of subcellular organization on homeostasis

Plant hormones are master regulators of plant growth and development. Better knowledge of their spatial signaling and homeostasis (transport and metabolism) on the lowest structural levels (cellular and subcellular) is therefore crucial to a better understanding of developmental processes in plants. Recent progress in phytohormone analysis at the cellular and subcellular levels has greatly improved the effectiveness of isolation protocols and the sensitivity of analytical methods. This review is mainly focused on homeostasis of two plant hormone groups, auxins and cytokinins. It will summarize and discuss their tissue- and cell-type specific distributions at the cellular and subcellular levels

From laterally modulated two-dimensional electron gas towards artificial graphene

Cyclotron resonance has been measured in far-infrared transmission of GaAs/Al$_x$Ga$_{1-x}$As heterostructures with an etched hexagonal lateral superlattice. Non-linear dependence of the resonance position on magnetic field was observed as well as its splitting into several modes. Our explanation, based on a perturbative calculation, describes the observed phenomena as a weak effect of the lateral potential on the two-dimensional electron gas. Using this approach, we found a correlation between parameters of the lateral patterning and the created effective potential and obtain thus insights on how the electronic miniband structure has been tuned. The miniband dispersion was calculated using a simplified model and allowed us to formulate four basic criteria that have to be satisfied to reach graphene-like physics in such systems

Highly asymmetric magnetic domain wall propagation due to coupling to a periodic pinning potential

Magneto-optical microscopy and magnetometry have been used to study 19 magnetization reversal in an ultrathin magnetically soft [Pt/Co]2 ferromagnetic film 20 coupled to an array of magnetically harder [Co/Pt]4 nanodots via a predominantly 21 dipolar interaction across a 3 nm Pt spacer. This interaction generates a spatially 22 periodic pinning potential for domain walls propagating through the continuous 23 magnetic film. When reversing the applied field with respect to the static nanodot 24 array magnetization orientation, strong asymmetries in the wall velocity and switching 25 fields are observed. Asymmetric switching fields mean that the hysteresis of the film is 26 characterized by a large bias field of dipolar origin which is linked to the wall velocity 27 asymmetry. This latter asymmetry, though large at low fields, vanishes at high fields 28 where the domains become round and compact. A field-polarity-controlled transition 29 from dendritic to compact faceted domain structures is also seen at low field and a 30 model is proposed to interpret the transition

Polarographic Investigations of Some Metal Monocarboxylato Complexes . I. Monocarboxylato Complexes of Lead

By the polarographic method of DeFord and Hume the stability constants of plumbous monocarboxylato co mplexes have been determined, in water solutions of a constant ionic s trength 2 and a con stant concentration of 2 M of monocarboxylic acid. The examinations were carried out in the monocarboxyla te concent r a t ion range up to 2 M. The following values of stability const a nts were obtained: formiato complexes /31= 13, /32 = 50, /33 = 30; acetato complexes /31 = 150 , /32 = 900, fJ3 = 3000; propionato complexes fJ 1 = 170, /J2 = 2200, /J3 = 5800 ; butyrato complexes /J 1 = 120 , /32 = 2000 , /3 3 = = 5800. It i s evident that with the increase of b ase strength and the size of the monoc arboxylate ion the complex stability increas es in the m\u27ljority of cases

Polarographic Investigations of Some Metal Monocarboxylato Complexes . I. Monocarboxylato Complexes of Lead

By the polarographic method of DeFord and Hume the stability constants of plumbous monocarboxylato co mplexes have been determined, in water solutions of a constant ionic s trength 2 and a con stant concentration of 2 M of monocarboxylic acid. The examinations were carried out in the monocarboxyla te concent r a t ion range up to 2 M. The following values of stability const a nts were obtained: formiato complexes /31= 13, /32 = 50, /33 = 30; acetato complexes /31 = 150 , /32 = 900, fJ3 = 3000; propionato complexes fJ 1 = 170, /J2 = 2200, /J3 = 5800 ; butyrato complexes /J 1 = 120 , /32 = 2000 , /3 3 = = 5800. It i s evident that with the increase of b ase strength and the size of the monoc arboxylate ion the complex stability increas es in the m\u27ljority of cases

On spontaneous scalarization

We study in the physical frame the phenomenon of spontaneous scalarization that occurs in scalar-tensor theories of gravity for compact objects. We discuss the fact that the phenomenon occurs exactly in the regime where the Newtonian analysis indicates it should not. Finally we discuss the way the phenomenon depends on the equation of state used to describe the nuclear matter.Comment: 41 pages, RevTex, 10 ps figures, submitted to Phys. Rev.

Spin-dependent phenomena and device concepts explored in (Ga,Mn)As

Over the past two decades, the research of (Ga,Mn)As has led to a deeper understanding of relativistic spin-dependent phenomena in magnetic systems. It has also led to discoveries of new effects and demonstrations of unprecedented functionalities of experimental spintronic devices with general applicability to a wide range of materials. In this article we review the basic material properties that make (Ga,Mn)As a favorable test-bed system for spintronics research and discuss contributions of (Ga,Mn)As studies in the general context of the spin-dependent phenomena and device concepts. Special focus is on the spin-orbit coupling induced effects and the reviewed topics include the interaction of spin with electrical current, light, and heat.Comment: 47 pages, 41 figure