1,554 research outputs found
XDJ1, a gene encoding a novel non-essential DnaJ homologue from Saccharomyces cerevisiae
The gene encoding a novel DnaJ-like protein, termed Xdj1, has been identified by amplification of Saccharomyces cerevisiae genomic DNA. An open reading frame of 1380 bp was detected. Disruption of XDJ1 did not yield any detectable new phenotype. A double-deletion strain containing a disruption of both XDJ1 and YDJ1, another gene coding for a DnaJ-like protein, was still viable. Under a variety of growth conditions, no XDJ1 transcripts could be detected by Northern blot analysis and no translation product was found by immunoblotting with antibody against Xdj1 produced in Escherichia coli. Thus, XDJ1 is either expressed only under very specific conditions or represents a silent gene
Optimizing the spin sensitivity of grain boundary junction nanoSQUIDs -- towards detection of small spin systems with single-spin resolution
We present an optimization study of the spin sensitivity of nanoSQUIDs based
on resistively shunted grain boundary Josephson junctions. In addition the dc
SQUIDs contain a narrow constriction onto which a small magnetic particle can
be placed (with its magnetic moment in the plane of the SQUID loop and
perpendicular to the grain boundary) for efficient coupling of its stray
magnetic field to the SQUID loop. The separation of the location of optimum
coupling from the junctions allows for an independent optimization of the
coupling factor and junction properties. We present different
methods for calculating (for a magnetic nanoparticle placed 10\,nm
above the constriction) as a function of device geometry and show that those
yield consistent results. Furthermore, by numerical simulations we obtain a
general expression for the dependence of the SQUID inductance on geometrical
parameters of our devices, which allows to estimate their impact on the
spectral density of flux noise of the SQUIDs in the thermal white
noise regime. Our analysis of the dependence of and on the
geometric parameters of the SQUID layout yields a spin sensitivity
of a few
( is the Bohr magneton) for optimized parameters, respecting
technological constraints. However, by comparison with experimentally realized
devices we find significantly larger values for the measured white flux noise,
as compared to our theoretical predictions. Still, a spin sensitivity on the
order of for optimized devices seems to be
realistic.Comment: 10 pages, 5 figures, Superconductor Science and Technology
(submitted
Controlled generation of a pn-junction in a waveguide integrated graphene photodetector
With its electrically tunable light absorption and ultrafast photoresponse,
graphene is a promising candidate for high-speed chip-integrated photonics. The
generation mechanisms of photosignals in graphene photodetectors have been
studied extensively in the past years. However, the knowledge about efficient
light conversion at graphene pn-junctions has not yet been translated into
high-performance devices. Here, we present a graphene photodetector integrated
on a silicon slot-waveguide, acting as a dual-gate to create a pn-junction in
the optical absorption region of the device. While at zero bias the
photo-thermoelectric effect is the dominant conversion process, an additional
photoconductive contribution is identified in a biased configuration. Extrinsic
responsivities of 35 mA/W, or 3.5 V/W, at zero bias and 76 mA/W at 300 mV bias
voltage are achieved. The device exhibits a 3 dB-bandwidth of 65 GHz, which is
the highest value reported for a graphene-based photodetector.Comment: 19 pages, 16 figure
Die Expression des Epitops Sialyl Lewis X als prognostischer Faktor beim kolorektalen Karzinom
In der hier vorliegenden Arbeit wurde die prognostische Wertigkeit der immunhistochemisch detektierten Expression des auf den Zellwänden kolorektaler Karzinome auftretenden Glykoproteinepitops Sialyl LeX analysiert. In die Untersuchung wurden 215 Patienten mit einbezogen, die sich zwischen Januar 2000 und Dezember 2004 in der Chirurgischen Universitätsklinik Rostock der primären Resektion eines kolorektalen Karzinoms im UICC-Stadium III oder IV unterzogen. Für die Auswertung der Färbung wurde ein fünfstufiger, einfach anzuwendender Score entwickelt
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