944 research outputs found
Photoresponsive nutlin derivatives and uses thereof
The invention relates to the field of medicine and medicinal chemistry, more in particular to the design, manufacture and use of anti-cancer drugs that can be activated by an external stimulus that can be applied in a spatiotemporal fashion. Provided herein is a compound having the chemical structure or a pharmaceutically acceptable salt thereof
Three-Body Halos. II. from Two- to Three-Body Asymptotics
The large distance behavior of weakly bound three-body systems is
investigated. The Schr\"{o}dinger equation and the Faddeev equations are
reformulated by an expansion in eigenfunctions of the angular part of a
corresponding operator. The resulting coupled set of effective radial equations
are then derived. Both two- and three-body asymptotic behavior are possible and
their relative importance is studied for systems where subsystems may be bound.
The system of two nucleons outside a core is studied numerically in detail and
the character of possible halo structure is pointed out and investigated.Comment: 16 pages, compressed and uuencoded PosrScript file, IFA-94/3
Anisotropic magnetoresistance in a 2DEG in a quasi-random magnetic field
We present magnetotransport results for a 2D electron gas (2DEG) subject to
the quasi-random magnetic field produced by randomly positioned sub-micron Co
dots deposited onto the surface of a GaAs/AlGaAs heterostructure. We observe
strong local and non-local anisotropic magnetoresistance for external magnetic
fields in the plane of the 2DEG. Monte-Carlo calculations confirm that this is
due to the changing topology of the quasi-random magnetic field in which
electrons are guided predominantly along contours of zero magnetic field.Comment: 4 pages, 6 figures, submitted to Phys. Rev.
Observation of Quantum Asymmetry in an Aharonov-Bohm Ring
We have investigated the Aharonov-Bohm effect in a one-dimensional
GaAs/GaAlAs ring at low magnetic fields. The oscillatory magnetoconductance of
these systems are for the first time systematically studied as a function of
density. We observe phase-shifts of in the magnetoconductance
oscillations, and halving of the fundamental period, as the density is
varied. Theoretically we find agreement with the experiment, by introducing an
asymmetry between the two arms of the ring.Comment: 4 pages RevTex including 3 figures, submitted to Phys. Rev.
Effect of intersubband scattering on weak localization in 2D systems
The theory of weak localization is generalized for multilevel 2D systems
taking into account intersubband scattering. It is shown that weak intersubband
scattering which is negligible in a classical transport, affects strongly the
weak-localization correction to conductivity. The anomalous magnetoresistance
is calculated in the whole range of classically low magnetic fields. This
correction to conductivity is shown to depend strongly on the ratios of
occupied level concentrations. It is demonstrated that at relatively low
population of the excited subband, it is necessary to use the present theory
because the high-field limit asimptotics is shown to be achieved only in
classical magnetic fields.Comment: 18 pages, 4 figures. Accepted to Phys. Rev. B 6
Biosynthesis of bioactive diterpenoids in the medicinal plant Vitex agnus‐castus
Vitex agnus‐castus L. (Lamiaceae) is a medicinal plant historically used throughout the Mediterranean region to treat menstrual cycle disorders, and is still used today as a clinically effective treatment for premenstrual syndrome. The pharmaceutical activity of the plant extract is linked to its ability to lower prolactin levels. This feature has been attributed to the presence of dopaminergic diterpenoids that can bind to dopamine receptors in the pituitary gland. Phytochemical analyses of V. agnus‐castus show that it contains an enormous array of structurally related diterpenoids and, as such, holds potential as a rich source of new dopaminergic drugs. The present work investigated the localisation and biosynthesis of diterpenoids in V. agnus‐castus . With the assistance of matrix‐assisted laser desorption ionisation‐mass spectrometry imaging (MALDI‐MSI), diterpenoids were localised to trichomes on the surface of fruit and leaves. Analysis of a trichome‐specific transcriptome database, coupled with expression studies, identified seven candidate genes involved in diterpenoid biosynthesis: three class II diterpene synthases (diTPSs); three class I diTPSs; and a cytochrome P450 (CYP). Combinatorial assays of the diTPSs resulted in the formation of a range of different diterpenes that can account for several of the backbones of bioactive diterpenoids observed in V. agnus‐castus . The identified CYP, Vac CYP76BK1, was found to catalyse 16‐hydroxylation of the diol‐diterpene, peregrinol, to labd‐13Z ‐ene‐9,15,16‐triol when expressed in Saccharomyces cerevisiae . Notably, this product is a potential intermediate in the biosynthetic pathway towards bioactive furan‐ and lactone‐containing diterpenoids that are present in this species
Probe-configuration dependent dephasing in a mesoscopic interferometer
Dephasing in a ballistic four-terminal Aharonov-Bohm geometry due to charge
and voltage fluctuations is investigated. Treating two terminals as voltage
probes, we find a strong dependence of the dephasing rate on the probe
configuration in agreement with a recent experiment by Kobayashi et al. (J.
Phys. Soc. Jpn. 71, 2094 (2002)). Voltage fluctuations in the measurement
circuit are shown to be the source of the configuration dependence.Comment: 4 pages, 3 figure
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