306 research outputs found
A 2-chain can interlock with a k-chain
One of the open problems posed in [3] is: what is the minimal number k such
that an open, flexible k-chain can interlock with a flexible 2-chain? In this
paper, we establish the assumption behind this problem, that there is indeed
some k that achieves interlocking. We prove that a flexible 2-chain can
interlock with a flexible, open 16-chain.Comment: 10 pages, 6 figure
Einstein on the beach: A study in temporality
This is an Author's Accepted Manuscript of an article published in Performance Research, 17(5), 34 - 40, 2012, copyright @ Taylor & Francis, available online at: http://www.tandfonline.com/10.1080/13528165.2012.728438.In this paper I seek to examine and analyse the sense of duration induced by performances of Einstein on the Beach, and the entailed sense of time which its internal structure creates. I initially sketch out the stylistic context and artistic intentions of this work's creators, Glass and Wilson, and I briefly describe the process of its creation. Certain features of this process indicate how the work may be interpreted. Having cited the creators' thoughts on structure and temporality, I address directly aspects of Einstein's temporal effects, comparing it to works of similar lengths. I give the briefest synopsis of its staging and motifs. I then outline three kinds of devices which seem to inform our temporal sense of this work as spectators. In the final section I invoke two ideas which serve as analogies to help characterise this work's overall effect on us: Heidegger's notion of the âhermeneutic circleâ and, more speculatively, Nietzsche's âtheoryâ of Eternal Recurrence
Triangular Spin-Orbit-Coupled Lattice with Strong Coulomb Correlations: Sn Atoms on a SiC(0001) Substrate
Two-dimensional (2D) atom lattices provide model setups for Coulomb
correlations inducing competing ground states, partly with topological
character. Hexagonal SiC(0001) is an intriguing wide-gap substrate,
spectroscopically separated from the overlayer and hence reduced screening. We
report the first study of an artificial high-Z atom lattice on SiC(0001) by Sn
adatoms, based on combined experimental realization and theoretical modeling.
Density-functional theory of our -structure model closely reproduces
the scanning tunneling microscopy. Instead of metallic behavior, photoemission
data show a deeply gapped state (~2 eV gap). Based on our calculations
including dynamic mean-field theory, we argue that this reflects a pronounced
Mott insulating scenario. We also find indications that the system is
susceptible to antiferromagnetic superstructures. Such spin-orbit-coupled
correlated heavy atom lattices on SiC(0001) thus form a novel testbed for
peculiar quantum states of matter, with potential bearing for spin liquids and
topological Mott insulators.Comment: 5 pages, 4 figures, 1 tabl
Smart framework for real-time monitoring and control of subsurface processes in managed aquifer recharge applications: project outlook
International audienc
Double-labelled HIV-1 particles for study of virusâcell interaction
AbstractHuman immunodeficiency virus (HIV) delivers its genome to a host cell through fusion of the viral envelope with a cellular membrane. While the viral and cellular proteins involved in entry have been analyzed in detail, the dynamics of virusâcell fusion are largely unknown. Single virus tracing (SVT) provides the unique opportunity to visualize viral particles in real time allowing direct observation of the dynamics of this stochastic process. For this purpose, we developed a double-coloured HIV derivative carrying a green fluorescent label attached to the viral matrix protein combined with a red label fused to the viral Vpr protein designed to distinguish between complete virions and subviral particles lacking MA after membrane fusion. We present here a detailed characterization of this novel tool together with exemplary live cell imaging studies, demonstrating its suitability for real-time analyses of HIVâcell interaction
Betriebliche Sanierungs- und Innovationsvereinbarungen in der Metall- und Elektroindustrie: nachhaltige BĂŒndnisse fĂŒr Innovations- und WettbewerbsfĂ€higkeit?
Die Befragung sollte einen ersten Eindruck davon vermitteln, wie die Umsetzung tariflicher Abweichungen vom FlĂ€chentarifvertrag in der Praxis bewertet werden. Angesichts eines nach wie vor vom FlĂ€chentarifvertrag dominierten Systems industrieller Beziehungen interessierte v.a. die Praxis betriebsspezifischer Differenzierungen. Wie werden Effizienz und EffektivitĂ€t dieser abweichenden Vereinbarungen von den Beteiligten eingeschĂ€tzt? Ein Blick auf die wirtschaftliche Wirklichkeit der deutschen Industrie zeigt, dass es lĂ€ngst nicht mehr um die Frage nach dem âobâ tariflicher Abweichungen geht, sondern nach dem âwieâ. Die Befragungsergebnisse sind dabei ĂŒber die befragten Firmen hinaus von Interesse, denn sie liefern Hinweise auf verallgemeinerbare positive und negative Randbedingungen und Erfahrungen. Ein wesentlicher Punkt ist hier die soziale und unternehmenskulturelle InnovationsfĂ€higkeit der beteiligten Unternehmen und ihrer Belegschaften. Um diese nachhaltig zu steigern (und gemeinsames Lernen in Konfliktsituationen zu ermöglichen), sind förderliche Rahmenbedingungen und ein adĂ€quates Verhalten der beteiligten Akteure notwendig. Hier zeigen die Ergebnisse der Interviews sowohl Positiv- als auch Negativbeispiele
Bone morphogenetic protein-7 release from endogenous neural precursor cells suppresses the tumourigenicity of stem-like glioblastoma cells
Glioblastoma cells with stem-like properties control brain tumour growth and recurrence. Here, we show that endogenous neural precursor cells perform an anti-tumour response by specifically targeting stem-like brain tumour cells. In vitro, neural precursor cells predominantly express bone morphogenetic protein-7; bone morphogenetic protein-7 is constitutively released from neurospheres and induces canonical bone morphogenetic protein signalling in stem-like glioblastoma cells. Exposure of human and murine stem-like brain tumour cells to neurosphere-derived bone morphogenetic protein-7 induces tumour stem cell differentiation, attenuates stem-like marker expression and reduces self-renewal and the ability for tumour initiation. Neurosphere-derived or recombinant bone morphogenetic protein-7 reduces glioblastoma expansion from stem-like cells by down-regulating the transcription factor Olig2. In vivo, large numbers of bone morphogenetic protein-7-expressing neural precursors encircle brain tumours in young mice, induce canonical bone morphogenetic protein signalling in stem-like glioblastoma cells and can thereby attenuate tumour formation. This anti-tumour response is strongly reduced in older mice. Our results indicate that endogenous neural precursor cells protect the young brain from glioblastoma by releasing bone morphogenetic protein-7, which acts as a paracrine tumour suppressor that represses proliferation, self-renewal and tumour-initiation of stem-like glioblastoma cell
Decrease in REM latency and changes in sleep quality parallel serotonergic damage and recovery after MDMA: a longitudinal study over 180 days
The recreational drug ecstasy [3,4-methylenedioxymethamphetamine
(MDMA)], has been found to selectively damage brain serotonin neurons
in experimental animals, and probably in human MDMA users, but detailed
morphometric analyses and parallel functional measures during damage
and recovery are missing. Since there is evidence that serotonin
regulates sleep, we have compared serotonergic markers parallel with
detailed analysis of sleep patterns at three time-points within 180 d
after a single dose of 15 mg/kg MDMA in male Dark Agouti rats. At 7 d
and 21 d after MDMA treatment, significant (30-40%), widespread
reductions in serotonin transporter (5-HTT) density were detected in
the cerebral cortex, hippocampus, most parts of the hypothalamus, and
some of the brainstem nuclei. With the exception of the hippocampus,
general recovery was observed in the brain 180 d after treatment.
Transient increases followed by decreases were detected in 5-HTT mRNA
expression of dorsal and median raphe nuclei at 7 d and 21 d after the
treatment. Significant reductions in rapid eye movement (REM) sleep
latency, increases in delta power spectra in non-rapid eye movement
sleep and increased fragmentation of sleep were also detected, but all
these alterations disappeared by the 180th day. The present data
provide evidence for long-term, albeit, except for the hippocampus,
transient changes in the terminal and cellular regions of the
serotonergic system after this drug. Reduced REM latency and increased
sleep fragmentation are the most characteristic alterations of sleep
consistently described in depression using EEG sleep polygraphy
A self-organized model for cell-differentiation based on variations of molecular decay rates
Systemic properties of living cells are the result of molecular dynamics
governed by so-called genetic regulatory networks (GRN). These networks capture
all possible features of cells and are responsible for the immense levels of
adaptation characteristic to living systems. At any point in time only small
subsets of these networks are active. Any active subset of the GRN leads to the
expression of particular sets of molecules (expression modes). The subsets of
active networks change over time, leading to the observed complex dynamics of
expression patterns. Understanding of this dynamics becomes increasingly
important in systems biology and medicine. While the importance of
transcription rates and catalytic interactions has been widely recognized in
modeling genetic regulatory systems, the understanding of the role of
degradation of biochemical agents (mRNA, protein) in regulatory dynamics
remains limited. Recent experimental data suggests that there exists a
functional relation between mRNA and protein decay rates and expression modes.
In this paper we propose a model for the dynamics of successions of sequences
of active subnetworks of the GRN. The model is able to reproduce key
characteristics of molecular dynamics, including homeostasis, multi-stability,
periodic dynamics, alternating activity, differentiability, and self-organized
critical dynamics. Moreover the model allows to naturally understand the
mechanism behind the relation between decay rates and expression modes. The
model explains recent experimental observations that decay-rates (or turnovers)
vary between differentiated tissue-classes at a general systemic level and
highlights the role of intracellular decay rate control mechanisms in cell
differentiation.Comment: 16 pages, 5 figure
- âŠ