Low-energy properties of fractional helical Luttinger liquids

We investigate the low-energy properties of (quasi) helical and fractional helical Luttinger liquids. In particular, we calculate the Drude peak of the optical conductivity, the density of states, as well as charge transport properties of the interacting system with and without attached Fermi liquid leads at small and large (compared to the gap) frequencies. For fractional wires, we find that the low energy tunneling density of states vanishes. The conductance of a fractional helical Luttinger liquid is non-integer. It is independent of the Luttinger parameters in the wire, despite the intricate mixing of charge and spin degrees of freedom, and only depends on the relative locking of charge and spin degrees of freedom.Comment: 9 pages, 4 figures. Final versio

Kondo effect on the surface of 3D topological insulators: Signatures in scanning tunneling spectroscopy

We investigate the scattering off dilute magnetic impurities placed on the surface of three-dimensional topological insulators. In the low-temperature limit, the impurity moments are Kondo-screened by the surface-state electrons, despite their exotic locking of spin and momentum. We determine signatures of the Kondo effect appearing in quasiparticle interference (QPI) patterns as recorded by scanning tunneling spectroscopy, taking into account the full energy dependence of the T matrix as well as the hexagonal warping of the surface Dirac cones. We identify a universal energy dependence of the QPI signal at low scanning energies as the fingerprint of Kondo physics, markedly different from the signal due to non-magnetic or static magnetic impurities. Finally, we discuss our results in the context of recent experimental data.Comment: 9 pages, 9 figure

Influence of surrogate L chain on DHJH-reading frame 2 suppression in mouse precursor B cells

DHJH rearrangements start in progenitor and precursor B cells and occur in three reading frames (rf). A strong bias for rf I has been noticed in murlne and chicken antibodies, while the representation of rf II has been found suppressed both in peripheral as well as in precursor B cells. H chain gene loci DHJH rearranged in rf II are potentially capable of expressing a truncated DnJHC, protein on the cell surface. Mice incapable of expressing this protein on the surface have previously been shown to have all reading frames represented in near equal frequency, suggesting that membrane-bound DHJHCμ protein is involved in the suppression of rf II. In this paper we show that suppression of rf II Is not yet established in c-kit+ CD43+ IL-7/stromal cell-reactive pre-B I cells of fetal liver at day 15 of gestation, but becomes established when such precursor cell populations are expanded in vitro on stromal cells in the presence of IL-7. H chain gene loci using the DQ52 segment for rearrangements (which contains a stop codon in rf II, thus being unable to make DHJHCμ protein) do not show rf II suppression under these conditions. The same type of fetal liver-derived pro B-l cells from λ5 deficient mice also do not show rf II suppression after in vitro expansion. Bone marrow-derived pre B-I cells from normal mice assayed ex vivo and expanded in vivo show rf II suppression, while the corresponding pre-B I cells from λ5T mice do not. Collectively these experiments suggest that surrogate L chain Is involved in rf II suppression. This may happen by inhibition of proliferation of pre-B cells expressing a complex of DHJHCμ protein and surrogate L chai

Neutrophil elastase is the 'histone H2A-specific protease'

Fundamental changes in the epigenetic status of histones from hematopoietic stem cells might be one of the driving forces behind many malignant transformations and subsequent leukemia development. The amino-terminal tail of histones and the carboxy-tail of histone H2A protrude from the nucleosome and can be modified by many different posttranslational modifications (PTM) on at least 60 different residues, thereby mediating chromatin dynamics. During an iTRAQ proteome analysis on Chronic Lymphocytic Leukemia (CLL) B-cells we came across a specific kind of histone modification that has received only little attention in epigenetics until now: histone clipping. The clipping of the histone H2A C-tail at V114 was more abundant in the CLL B-cell clones compared to healthy B-cells. This specific proteolytic product was already described in the context of leukemia in the late 70’s and is still being referenced today. To specifically quantify this clipping product, we developed and optimized a sensitive and high throughput AQUA approach, based on two isotopically labeled synthetic peptides. We screened 36 patients to investigate any discriminative power of clipped H2A as a potential prognostic marker. In doing so, we found that clipping mainly occurs in the myeloid lineage and has no clear link to the CLL B-cell clone. Here we show that the responsible enzyme, until now known as the “H2A specific protease”, but previously not identified, actually is Neutrophil Elastase. With the growing interest in the epigenetic potential of histone clipping we emphasize its potential role in hematopoietic differentiation

Possible environmental effects on the evolution of the Alps-Molasse Basin system

We propose three partly unrelated stages in the geodynamic evolution of the Alps and the sedimentary response of the Molasse Basin. The first stage comprises the time interval between ca. 35 and 20 Ma and is characterized by a high ratio between rates of crustal accretion and surface erosion. The response of the Molasse Basin was a change from the stage of basin underfill (UMM) to overfill (USM). Because the response time of erosional processes to crustal accretion and surface uplift lasts several millions of years, the orogen first experienced a net growth until the end of the Oligocene. As a result, the Molasse basin subsided at high rates causing the topographic axis to shift to the proximal basin border and alluvial fans to establish at the thrust front. During the Aquitanian, however, ongoing erosion and downcutting in the hinterland caused sediment discharge to the basin to increase and the ratio between the rates of crustal accretion and surface erosion to decrease. The result was a progradation of the dispersal systems, and a shift of the topographic axis towards the distal basin border. The second stage started at ca. 20 Ma at a time when palaeoclimate became more continental, and when the crystalline core became exposed in the orogen. The effect was a decrease in the erosional efficiency of the Swiss Alps and hence a reduction of sediment discharge to the Molasse Basin. We propose that this decrease in sediment flux caused the Burdigalian transgression of the OMM. We also speculate that this reduction of surface erosion initiated the modification of Alpine deformation from vertically- to mainly horizontally directed extrusion (deformation of the Southern Alps, and the Jura Mountains some Ma later). The third stage in the geodynamic development was initiated at the Miocene/Pliocene boundary. At that time, palaeoclimate possibly became wetter, which, in turn, caused surface erosion to increase relative to crustal accretion. This change caused the Alps to enter a destructive stage and the locus of active deformation to shift towards to the orogenic core. It also resulted in a net unloading of the orogen and thus in a flexural rebound of the foreland plate. We conclude that the present chronological resolution is sufficient to propose possible feedback mechanisms between environmental effects and lithospheric processes. Further progress will result from a down-scaling in research. Specifically, we anticipate that climate-driven changes in sediment flux altered the channel geometries of USM and OSM deposits, the pattern of sediment transport and thus the stacking arrangement of architectural elements. This issue has not been sufficiently explored and awaits further detailed quantitative studie

Rearrangement and expression of χ light chain genes can occur without μ heavy chain expression during differentiation of pre-B cells

The kinetics of χ light (χL) chain gene rearrangement and expression on mRNA and protein level has been studied with four stromal cell/IL-7 reactive, long-term in vitro proliferating pre-B cell lines and clones, two from fetal liver of normal mice and two from fetal liver of EμH-bcl-2 transgenic (bcl-2-tg) mice. These pre-B cell lines and clones are DJH-rearranged on both H chain alleles. Two of the clones harbor H chain rearrangements which do not allow the expression of VHDJH rearranged H chain genes as μH chain proteins. Upon removal of IL-7 from the pre-B cell cultures all four cell lines rearrange VH-DJH and VL-JL gene segments, loose the surface expression of c-kit, CD43, and surrogate light chain, as well as the capacity to be clonable on stromal cells in the presence of IL-7. Pre-B cells from normal mice die by apoptosis during differentiation, while those from bcl-2-tg mice do not. All four lines and clones express comparable levels of mRNA for μH and μL chains with the same time kinetics during 3 days of differentiation. However, only two of the four pre-B cell lines and clones express μH chain protein, whereas all four pre-B cell lines and clones express μL chain protein at comparable levels between 2×105 and 1.40×106 μL chain molecules per cell. These results suggest that μH chain expression is not mandatory for rearrangement and normal expression of μL chain genes when pre-B cells differentiate to B cell

Current state of ASoC design methodology

This paper gives an overview of the current state of ASoC design methodology and presents preliminary results on evaluating the learning classifier system XCS for the control of a QuadCore. The ASoC design methodology can determine system reliability based on activity, power and temperature analysis, together with reliability block diagrams. The evaluation of the XCS shows that in the evaluated setup, XCS can find optimal operating points, even in changed environments or with changed reward functions. This even works, though limited, without the genetic algorithm the XCS uses internally. The results motivate us to continue the evaluation for more complex setups

Energy transport between critical one-dimensional systems with different central charges

Energy transport can reveal information about interacting many-body systems beyond other transport probes. In particular, in one dimension it has been shown that the energy current is directly proportional to the central charge, thus revealing information about the degrees of freedom of critical systems. In this work, we explicitly verify this result in two cases for translationally invariant systems based on explicit microscopic calculations. More importantly, we generalise the result to non-translation invariant setups and use this to study a composite system of two subsystems possessing different central charges. We find a bottleneck effect meaning the smaller central charge limits the energy transport

Slip rates variability and sediment mobilization on a shallow landslide in the northern Swiss Alps

Geomorphic and morphometric data imply that process rates of the Schimbrig landslide, located in the Entle watershed (Central Switzerland), are still limited by the elevation of the LGM base level. At present, the Entle watershed is in a stage of adjusting to the lowered post-glacial base level as indicated by knick zones in the trunk stream. Some thousands of years later when these knick zones will reach the Schimbrig site, we anticipate a substantial increase in process rates and sediment flux for the landslide. The pattern of slip rates was measured on the Schimbrig landslide over a 14-months period. We propose that a Bingham plastic model explains much of how measured slip rates are linked to the observed topography, climatic variations and thickness variability of the landslide mass. This model explains why slip rates have been highest where the thickness of the material is substantially higher. It also explains why slip rates are highest in late summer/autumn and early spring. It appears then that snow melt in spring and decreasing temperatures in late summer/autumn potentially result in a high retention of the pore water and thus in a low viscosity of the material, which, in turns, promotes slip rates. Interestingly, an extreme rainstorm like the one of August 2005 only had a local impact on the landslide mass by triggering small scale earth flows and debris flows. This implies that the earth slide material does not directly respond to an episodic pattern of rainfall. Such precipitation events, however, superimpose a smaller-scale imprint on the landslide relie