Multiple roles for membrane-associated protein trafficking and signaling in gravitropism

Gravitropism is a process that allows plant organs to guide their growth relative to the gravity vector. It requires them to sense changes in their orientation and generate a biochemical signal that they transmit to the tissues that drive organ curvature. Trafficking between the plasma membrane and endosomal compartments is important for all of these phases of the gravitropic response. The sedimentation of starch-filled organelles called amyloplasts plays a key role in sensing reorientation, and vacuolar integrity is required for amyloplast sedimentation in shoots. Other proteins associated with the vesicle trafficking pathway contribute to early gravity signal transduction independently of amyloplast sedimentation in both roots and hypocotyls. Phosphatidylinositol signaling, which starts at the plasma membrane and later affects the localization of auxin efflux facilitators, is a likely second messenger in the signal transduction phase of gravitropism. Finally, membrane-localized auxin influx and efflux facilitators contribute to a differential auxin gradient across the gravistimulated organs, which directs root curvature

Flagellar sensilla in male and female European beewolves, Philanthus triangulum F. (Hymenoptera: Sphecidae)

We investigated the morphology of the antennal sensilla of a sphecid wasp, the European beewolf Philanthus triangulum, to provide an inventory for the species and to compare the sensillar equipment between the sexes. The density of sensilla increased from the base to the tip of the antennae. We distinguished nine different types of sensilla. One type has not yet been described in Hymenoptera. The large sensilla basiconica occurred only on the antennae of female beewolves. We discuss the functional significance of the difference between the sexes and compare our results with data from other sphecids and the honeybee Apis mellifera

Compact hollow fibre reactors for efficient methane conversion

In this study, a micro-structured catalytic hollow fiber membrane reactor (CHFMR) has been prepared, characterized and evaluated for performing steam methane reforming (SMR) reaction, using Rh/CeO2 as the catalyst and a palladium membrane for separating hydrogen from the reaction. Preliminary studies on a catalytic hollow fiber (CHF), a porous membrane reactor configuration without the palladium membrane, revealed that stable methane conversions reaching equilibrium values can be achieved, using approximately 36mg of 2wt.%Rh/CeO2 catalyst incorporated inside the micro-channels of alumina hollow fibre substrates (around 7cm long in the reaction zone). This proves the advantages of efficiently utilizing catalysts in such a way, such as significantly reduced external mass transfer resistance when compared with conventional packed bed reactors. It is interesting to observe catalyst deactivation in CHF when the quantity of catalyst incorporated is less than 36mg, although the Rh/CeO2 catalyst supposes to be quite resistant against carbon formation. The "shift" phenomenon expected in CHFMR was not observed by using 100mg of 2wt.%Rh/CeO2 catalyst, mainly due to the less desired catalyst packing at the presence of the dense Pd separating layer. Problems of this type were solved by using 100mg of 4wt.% Rh/CeO2 as the catalyst in CHFMR, resulting in methane conversion surpassing the equilibrium conversions and no detectable deactivation of the catalyst. As a result, the improved methodology of incorporating catalyst into the micro-channels of CHFMR is the key to a more efficient membrane reactor design of this type, for both the SMR in this study and the other catalytic reforming reactions

Anomalous Self-Energy Effects of the B_1g Phonon in Y_{1-x}(Pr,Ca)_xBa_2Cu_3O_7 Films

In Raman spectra of cuprate superconductors the gap shows up both directly, via a redistribution of the electronic background, the so-called "2Delta peaks", and indirectly, e.g. via the renormalization of phononic excitations. We use a model that allows us to study the redistribution and the related phonon self-energy effects simultaneously. We apply this model to the B_1g phonon of Y_{1-x}(Pr,Ca)_xBa_2Cu_3O_7 films, where Pr or Ca substitution enables us to investigate under- and overdoped samples. While various self-energy effects can be explained by the strength and energy of the 2\Delta peaks, anomalies remain. We discuss possible origins of these anomalies.Comment: 6 pages including 4 figure

Raman study of carrier-overdoping effects on the gap in high-Tc superconducting cuprates

Raman scattering in the heavily overdoped (Y,Ca)Ba_2Cu_3O_{7-d} (T_c = 65 K) and Bi_2Sr_2CaCu_2O_{8+d} (T_c = 55 K) crystals has been investigated. For the both crystals, the electronic pair-breaking peaks in the A_{1g} and B_{1g} polarizations were largely shifted to the low energies close to a half of 2Delta_0, Delta_0 being the maximum gap. It strongly suggests s-wave mixing into the d-wave superconducting order parameter and the consequent manifestation of the Coulomb screening effect in the B_{1g}-channel. Gradual mixing of s-wave component with overdoping is not due to the change of crystal structure symmetry but a generic feature in all high-T_c superconducting cuprates.Comment: 5 pages, 4 figures, to be published in Phys. Rev. B, Rapid communicaito

Coherent control of collective nuclear quantum states via transient magnons

Ultrafast and precise control of quantum systems at x-ray energies involves photons with oscillation periods below 1 as. Coherent dynamic control of quantum systems at these energies is one of the major challenges in hard x-ray quantum optics. Here, we demonstrate that the phase of a quantum system embedded in a solid can be coherently controlled via a quasi-particle with subattosecond accuracy. In particular, we tune the quantum phase of a collectively excited nuclear state via transient magnons with a precision of 1 zs and a timing stability below 50 ys. These small temporal shifts are monitored interferometrically via quantum beats between different hyperfine-split levels. The experiment demonstrates zeptosecond interferometry and shows that transient quasi-particles enable accurate control of quantum systems embedded in condensed matter environments

Bilaterale massive makronoduläre Nebennierenhyperplasie

Bei einem 46jährigen Patienten bestand seit 10 Jahren eine arterielle Hypertonie. In den letzten beiden Jahren entwickelten sich eine stammbetonte Adipositas sowie weitere typische Stigmata eines Cushing-Syndroms. Hormonanalysen ergaben einen Hypercortisolismus und ein supprimiertes Plasma-ACTH. Der Dexamethason-Hommtest erbrachte keine signifikante Suppression des Serum-Cortisols. Im CRH-Test und im Metopiron®-Test erwies sich das Plasma-ACTH als nicht stimulierbar. Im ACTH-Kurztest fand sich ein überschießender Cortisolanstieg. Die abdominelle Computertomographie zeigte beidseits stark vergrößerte (6 × 4 cm), großknotig veränderte Nebennieren. Eine adrenostatische Therapie mit Ketoconazol (400 mg/d) führte zu Symptomen der adrenalen Insuffizienz, eine reduzierte Dosis von 200 mg/d senkte das Serum-Cortisol auf Werte zwischen 5 und 11 µg/dl und normalisierte den Blutdruck, und die klinischen Symptome des Cushing-Syndroms bildeten sich zurück. Die anschließende bilaterale Adrenalektomie bestätigte die Diagnose einer massiven makronodulären Nebennierenhyperplasie. Postoperativ wurde eine Substitutionstherapie mit zweimal 25 mg/d Cortisonacetat und 0,05 mg/d Fludrocortison eingeleitet

Phonon Hall effect in ionic crystals in the presence of static magnetic field

We study phonon Hall effect (PHE) for ionic crystals in the presence of static magnetic field. Using Green-Kubo formula, we present an exact calculation of thermal conductivity tensor by considering both positive and negative frequency phonons. Numerical results are shown for some lattices such as hexagonal lattices, triangular lattices, and square lattices. We find that the PHE occurs on the nonmagnetic ionic crystal NaCl, although the magnitude is very small which is due to the tiny charge-to-mass ratio of the ions. The off-diagonal thermal conductivity is finite for nonzero magnetic field and changes sign for high value of magnetic field at high temperature. We also found that the off-diagonal thermal conductivity diverges as $\pm{1/T}$ at low temperature

Electronic Raman scattering in YBCO and other superconducting cuprates

Superconductivity induced structures in the electronic Raman spectra of high-Tc superconductors are computed using the results of ab initio LDA-LMTO three-dimensional band structure calculations via numerical integrations of the mass fluctuations, either in the whole 3D Brillouin zone or limiting the integrations to the Fermi surface. The results of both calculations are rather similar, the Brillouin zone integration yielding additional weak structures related to the extended van Hove singularities. Similar calculations have been performed for the normal state of these high-Tc cuprates. Polarization configurations have been investigated and the results have been compared to experimental spectra. The assumption of a simple d_(x^2-y^2)-like gap function allows us to explain a number of experimental features but is hard to reconcile with the relative positions of the A1g and B1g peaks.Comment: 14 pages, LaTeX (RevTeX), 5 PostScript figures, uses multicol.sty, submitted to PR