2,010 research outputs found
Pan-European backcasting exercise, enriched with regional perspective, and including a list of short-term policy options
This deliverable reports on the results of the third and final pan-European stakeholder meeting and secondly, on the enrichment with a Pilot Area and regional perspective. The main emphasis is on backcasting as a means to arrive at long-term strategies and short-term (policy) actions
Dynamical correlations in electronic transport through a system of coupled quantum dots
Current auto- and cross-correlations are studied in a system of two
capacitively coupled quantum dots. We are interested in a role of Coulomb
interaction in dynamical correlations, which occur outside the Coulomb blockade
region (for high bias). After decomposition of the current correlation
functions into contributions between individual tunneling events, we can show
which of them are relevant and lead to sub-/supper-Poissonian shot noise and
negative/positive cross-correlations. The results are differentiated for a weak
and strong inter-dot coupling. Interesting results are for the strong coupling
case when electron transfer in one of the channel is strongly correlated with
charge drag in the second channel. We show that cross-correlations are
non-monotonic functions of bias voltage and they are in general negative
(except some cases with asymmetric tunnel resistances). This is effect of local
potential fluctuations correlated by Coulomb interaction, which mimics the
Pauli exclusion principle
A Multi-model Analysis of Post-2020 Mitigation Efforts of Five Major Economies
This paper looks into the regional mitigation strategies of five major economies (China, EU, India, Japan and USA) in the context of the 2 degrees C target, using a multi-model comparison. In order to stay in line with the 2 degrees C target, a tripling or quadrupling of mitigation ambitions is required in all regions by 2050, employing vigorous decarbonization of the energy supply system and achieving negative emissions during the second half of the century. In all regions looked at, decarbonization of energy supply (and in particular power generation) is more important than reducing energy demand. Some differences in abatement strategies across the regions are projected: In India and the USA the emphasis is on prolonging fossil fuel use by coupling conventional technologies with carbon storage, whereas the other main strategy depicts a shift to carbon-neutral technologies with mostly renewables (China, EU) or nuclear power (Japan). Regions with access to large amounts of biomass, such as the USA, China and the EU, can make a trade-off between energy related emissions and land related emissions, as the use of bioenergy can lead to a net increase in land use emissions. After supply-side changes, the most important abatement strategy focuses on enduse efficiency improvements, leading to considerable emission reductions in both the industry and transport sectors across all regions. Abatement strategies for non-CO2 emissions and land use emissions are found to have a smaller potential. Inherent model, as well as collective, biases have been observed affecting the regional response strategy or the available reduction potential in specific (end-use) sectors
Anomalous Transient Current in Nonuniform Semiconductors
Nonequilibrium processes in semiconductors are considered with highly
nonuniform initial densities of charge carriers. It is shown that there exist
such distributions of charge densities under which the electric current through
a sample displays quite abnormal behaviour flowing against the applied voltage.
The appearance of this negative electric current is a transient phenomenon
occurring at the initial stage of the process. After this anomalous negative
fluctuation, the electric current becomes normal, i.e. positive as soon as the
charge density becomes more uniform. Several possibilities for the practical
usage of this effect are suggested.Comment: 1 file, 11 pages, RevTex, no figure
Metal-responsive gene regulation and metal transport in Helicobacter species
Helicobacter species are among the most successful colonizers of the mammalian gastrointestinal and hepatobiliary tract. Colonization is usually lifelong, indicating that Helicobacter species have evolved intricate mechanisms of dealing with stresses encountered during colonization of host tissues, like restriction of essential metal ions. The recent availability of genome sequences of the human gastric pathogen Helicobacter pylori, the murine enterohepatic pathogen Helicobacter hepaticus and the unannotated genome sequence of the ferret gastric pathogen Helicobacter mustelae has allowed for comparitive genome analyses. In this review we present such analyses for metal transporters, metal-storage and metal-responsive regulators in these three Helicobacter species, and discuss possible contributions of the differences in metal metabolism in adaptation to the gastric or enterohepatic niches occupied by Helicobacter species
Fibulin-4 deficiency differentially affects cytoskeleton structure and dynamics as well as TGF beta signaling
Fibulin-4 is an extracellular matrix (ECM) protein essential for elastogenesis and mutations in this
Spin effects in single electron tunneling
An important consequence of the discovery of giant magnetoresistance in
metallic magnetic multilayers is a broad interest in spin dependent effects in
electronic transport through magnetic nanostructures. An example of such
systems are tunnel junctions -- single-barrier planar junctions or more complex
ones. In this review we present and discuss recent theoretical results on
electron and spin transport through ferromagnetic mesoscopic junctions
including two or more barriers. Such systems are also called ferromagnetic
single-electron transistors. We start from the situation when the central part
of a device has the form of a magnetic (or nonmagnetic) metallic nanoparticle.
Transport characteristics reveal then single-electron charging effects,
including the Coulomb staircase, Coulomb blockade, and Coulomb oscillations.
Single-electron ferromagnetic transistors based on semiconductor quantum dots
and large molecules (especially carbon nanotubes) are also considered. The main
emphasis is placed on the spin effects due to spin-dependent tunnelling through
the barriers, which gives rise to spin accumulation and tunnel
magnetoresistance. Spin effects also occur in the current-voltage
characteristics, (differential) conductance, shot noise, and others. Transport
characteristics in the two limiting situations of weak and strong coupling are
of particular interest. In the former case we distinguish between the
sequential tunnelling and cotunneling regimes. In the strong coupling regime we
concentrate on the Kondo phenomenon, which in the case of transport through
quantum dots or molecules leads to an enhanced conductance and to a pronounced
zero-bias Kondo peak in the differential conductance.Comment: topical review (36 figures, 65 pages), to be published in J. Phys.:
Condens. Matte
Balloon cells promote immune system activation in focal cortical dysplasia type 2b
AIMS: Focal cortical dysplasia (FCD) type 2 is an epileptogenic malformation of the neocortex associated with somatic mutations in the mammalian target of rapamycin (mTOR) pathway. Histopathologically, FCD 2 is subdivided into FCD 2a and FCD 2b, the only discriminator being the presence of balloon cells (BCs) in FCD 2b. While pro‐epileptogenic immune system activation and inflammatory responses are commonly detected in both subtypes, it is unknown what contextual role BCs play. METHODS: The present study employed RNA sequencing of surgically resected brain tissue from FCD 2a (n = 11) and FCD 2b (n = 20) patients compared to autopsy control (n = 9) focusing on three immune system processes: adaptive immunity, innate immunity and cytokine production. This analysis was followed by immunohistochemistry on a clinically well‐characterised FCD 2 cohort. RESULTS: Differential expression analysis revealed stronger expression of components of innate immunity, adaptive immunity and cytokine production in FCD 2b than in FCD 2a, particularly complement activation and antigen presentation. Immunohistochemical analysis confirmed these findings, with strong expression of leukocyte antigen I and II in FCD 2b as compared to FCD 2a. Moreover, T‐lymphocyte tissue infiltration was elevated in FCD 2b. Expression of markers of immune system activation in FCD 2b was concentrated in subcortical white matter. Lastly, antigen presentation was strongly correlated with BC load in FCD 2b lesions. CONCLUSION: We conclude that, next to mutation‐driven mTOR activation and seizure activity, BCs are crucial drivers of inflammation in FCD 2b. Our findings indicate that therapies targeting inflammation may be beneficial in FCD 2b
Stationary states and phase diagram for a model of the Gunn effect under realistic boundary conditions
A general formulation of boundary conditions for semiconductor-metal contacts
follows from a phenomenological procedure sketched here. The resulting boundary
conditions, which incorporate only physically well-defined parameters, are used
to study the classical unipolar drift-diffusion model for the Gunn effect. The
analysis of its stationary solutions reveals the presence of bistability and
hysteresis for a certain range of contact parameters. Several types of Gunn
effect are predicted to occur in the model, when no stable stationary solution
exists, depending on the value of the parameters of the injecting contact
appearing in the boundary condition. In this way, the critical role played by
contacts in the Gunn effect is clearly stablished.Comment: 10 pages, 6 Post-Script figure
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