141 research outputs found
Monetary Policy in a Small Open Economy Model: A DSGE-VAR Approach for Switzerland
We study the transmission of monetary shocks and monetary policy with a behavioral model, corrected for potential misspecification using the DSGE-VAR framework elaborated by DelNegro and Schorfheide (2004). In particular, we investigate if the central bank should react to movements in the nominal exchange rate. We contribute to the empirical literature as we use Swiss data, which is very rarely used in that context.
External control strategies for self-propelled particles: optimizing navigational efficiency in the presence of limited resources
We experimentally and numerically study the dependence of different
navigation strategies regarding the effectivity of an active particle to reach
a predefined target area. As the only control parameter, we vary the particle's
propulsion velocity depending on its position and orientation relative to the
target site. By introducing different figures of merit, e.g. the time to target
or the total consumed propulsion energy, we are able to quantify and compare
the efficiency of different strategies. Our results suggest, that each strategy
to navigate towards a target, has its strengths and weaknesses and none of them
outperforms the other in all regards. Accordingly, the choice of an ideal
navigation strategy will strongly depend on the specific conditions and the
figure of merit which should be optimized
Efficient Radio Frequency filters for space constrained cryogenic set-ups
Noise filtering is an essential part for measurement of quantum phenomena at
extremely low temperatures. Here, we present the design of a filter which can
be installed in space constrained cryogenic environment containing a large
number of signal carrying lines. Our filters have a -3db point of 65kHz and its
performance at GHz frequencies are comparable to the best available RF filters.Comment: 9 pages, 4 figures, The capacitor reference in the first version was
wrong and has been changed to the right on
Theoretical, numerical, and experimental study of a flying qubit electronic interferometer
We discuss an electronic interferometer recently measured by Yamamoto et al.
This "flying quantum bit" experiment showed quantum oscillations between
electronic trajectories of two tunnel-coupled wires connected via an
Aharanov-Bohm ring. We present a simple scattering model as well as a numerical
microscopic model to describe this experiment. In addition, we present new
experimental data to which we confront our numerical results. While our
analytical model provides basic concepts for designing the flying qubit device,
we find that our numerical simulations allow to reproduce detailed features of
the transport measurements such as in-phase and anti-phase oscillations of the
two output currents as well as a smooth phase shift when sweeping a side gate.
Furthermore, we find remarkable resemblance for the magneto conductance
oscillations in both conductance and visibility between simulations and
experiments within a specific parameter range.Comment: 10 pages, 13 figure
Administration of a VEGFR‑2-specific MRI contrast agent to assess orthodontic tooth movement
Purpose
It is thought that orthodontic forces initially reduce periodontal blood flow during orthodontic tooth movement (OTM) via tissue compression with cells responding to concomitant oxygen deprivation with expression of vascular endothelial growth factor (VEGF) triggering angiogenesis via binding to its receptor VEGFR‑2. To test this hypothesis, we performed a pilot study to establish a protocol for molecular magnetic resonance imaging (MRI) of rat jaws administering a VEGFR-2-specific contrast agent.
Methods
Mesial OTM of a first upper left rat molar was initiated in one male Fischer 344 rat 4 days prior to MRI by insertion of an elastic band between the first and second upper molars with the contralateral side left untreated (internal control). T1-weighted MRI sequences including dynamic contrast-enhanced MRI (DCE-MRI) were recorded before and after administration of a molecular VEGFR‑2 MRI marker with a 7 T MRI dedicated for small animal use.
Results
After injection of anti-VEGFR2-albumin-gadolinium-DTPA, volume enhancement on T1-weighted images was increased at the OTM side distally of the moved first upper molar (M1) compared to the control side, whereas the T1 relaxation time was reduced on the OTM side. DCE-MRI resulted in an increased area under the curve (AUC), whereas time-to-peak (TTP) and washout rate were reduced during OTM distally of the moved M1 compared to the contralateral side.
Conclusions
OTM resulted in uptake of the VEGFR-2-specific MRI contrast agent in tension areas of the periodontal ligament. The imaging protocol presented here is useful for the assessment of VEGFR‑2 expression in tension areas of the periodontal ligament in vivo
alpha-Synuclein: a Modulator During Inflammatory CNS Demyelination
Abstract
Neuroinflammation and demyelination are hallmarks of several neurological disorders such as multiple sclerosis and multiple system atrophy. To better understand the underlying mechanisms of de- and regeneration in respective diseases, it is critical to identify factors modulating these processes. One candidate factor is alpha-Synuclein (aSyn), which is known to be involved in the pathology of various neurodegenerative diseases. Recently, we have shown that aSyn is involved in the modulation of peripheral immune responses during acute neuroinflammatory processes. In the present study, the effect of aSyn deficiency on de- and regenerative events in the CNS was analyzed by using two different demyelinating animal models: chronic MOG35–55-induced experimental autoimmune encephalomyelitis (EAE) and the cuprizone model. Histopathological analysis of spinal cord cross sections 8 weeks after EAE induction revealed a significant reduction of CNS inflammation accompanied by decreased myelin loss during late-stage inflammatory demyelination in aSyn-deficient mice. In contrast, after cuprizone-induced demyelination or remyelination following withdrawal of cuprizone, myelination and neuroinflammatory patterns were not affected by aSyn deficiency. These data provide further evidence for aSyn as regulator of peripheral immune responses under neuroinflammatory conditions, thereby also modulating degenerative events in late-stage demyelinating disease
Comprehensive phenotyping revealed transient startle response reduction and histopathological gadolinium localization to perineuronal nets after gadodiamide administration in rats
Gadolinium based contrast agents (GBCAs) are widely used in clinical MRI since the mid-1980s. Recently, concerns have been raised that trace amounts of Gadolinium (Gd), detected in brains even long time after GBCA application, may cause yet unrecognized clinical consequences. We therefore assessed the behavioral phenotype, neuro-histopathology, and Gd localization after repeated administration of linear (gadodiamide) or macrocyclic (gadobutrol) GBCA in rats. While most behavioral tests revealed no difference between treatment groups, we observed a transient and reversible decrease of the startle reflex after gadodiamide application. Residual Gd in the lateral cerebellar nucleus was neither associated with a general gene expression pathway deregulation nor with neuronal cell loss, but in gadodiamide-treated rats Gd was associated with the perineuronal net protein aggrecan and segregated to high molecular weight fractions. Our behavioral finding together with Gd distribution and speciation support a substance class difference for Gd presence in the brain after GBCA application
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