2,270 research outputs found
Measurements of Plasma Parameters Using a Fast Sweeping Langmuir Probe in the VINETA-II magnetic reconnection experiment
Self-Referential Noise and the Synthesis of Three-Dimensional Space
Generalising results from Godel and Chaitin in mathematics suggests that
self-referential systems contain intrinsic randomness. We argue that this is
relevant to modelling the universe and show how three-dimensional space may
arise from a non-geometric order-disorder model driven by self-referential
noise.Comment: Figure labels correcte
The role of the cancer stem cell marker CD271 in DNA damage response and drug resistance of melanoma cells
Several lines of evidence have suggested that stemness and acquired resistance
to targeted inhibitors or chemotherapeutics are mechanistically linked. Here
we observed high cell surface and total levels of nerve growth factor
receptor/CD271, a marker of melanoma-initiating cells, in sub-populations of
chemoresistant cell lines. CD271 expression was increased in drug-sensitive
cells but not resistant cells in response to DNA-damaging chemotherapeutics
etoposide, fotemustine and cisplatin. Comparative analysis of melanoma cells
engineered to stably express CD271 or a targeting short hairpin RNA by
expression profiling provided numerous genes regulated in a CD271-dependent
manner. In-depth analysis of CD271-responsive genes uncovered the association
of CD271 with regulation of DNA repair components. In addition, gene set
enrichment analysis revealed enrichment of CD271-responsive genes in drug-
resistant cells, among them DNA repair components. Moreover, our comparative
screen identified the fibroblast growth factor 13 (FGF13) as a target of
CD271, highly expressed in chemoresistant cells. Further we show that levels
of CD271 determine drug response. Knock-down of CD271 in fotemustine-resistant
cells decreased expression of FGF13 and at least partly restored sensitivity
to fotemustine. Together, we demonstrate that expression of CD271 is
responsible for genes associated with DNA repair and drug response. Further,
we identified 110 CD271-responsive genes predominantly expressed in melanoma
metastases, among them were NEK2, TOP2A and RAD51AP1 as potential drivers of
melanoma metastasis. In addition, we provide mechanistic insight in the
regulation of CD271 in response to drugs. We found that CD271 is potentially
regulated by p53 and in turn is needed for a proper p53-dependent response to
DNA-damaging drugs. In summary, we provide for the first time insight in a
CD271-associated signaling network connecting CD271 with DNA repair, drug
response and metastasis
Distinct patterns of thought mediate the link between brain functional connectomes and well-being
Ongoing thought patterns constitute important aspects of both healthy and abnormal human cognition. However, the neural mechanisms behind these daily experiences and their contribution to well-being remain a matter of debate. Here, using resting-state fMRI and retrospective thought sampling in a large neurotypical cohort (n = 211), we identified two distinct patterns of thought, broadly describing the participantsâ current concerns and future plans, that significantly explained variability in the individual functional connectomes. Consistent with the view that ongoing thoughts are an emergent property of multiple neural systems, network-based analysis highlighted the central importance of both unimodal and transmodal cortices in the generation of these experiences. Importantly, while state-dependent current concerns predicted better psychological health, mediating the effect of functional connectomes, trait-level future plans were related to better social health, yet with no mediatory influence. Collectively, we show that ongoing thoughts can influence the link between brain physiology and well-being
Physical Origin of the Boson Peak Deduced from a Two-Order-Parameter Model of Liquid
We propose that the boson peak originates from the (quasi-) localized
vibrational modes associated with long-lived locally favored structures, which
are intrinsic to a liquid state and are randomly distributed in a sea of
normal-liquid structures. This tells us that the number density of locally
favored structures is an important physical factor determining the intensity of
the boson peak. In our two-order-parameter model of the liquid-glass
transition, the locally favored structures act as impurities disturbing
crystallization and thus lead to vitrification. This naturally explains the
dependence of the intensity of the boson peak on temperature, pressure, and
fragility, and also the close correlation between the boson peak and the first
sharp diffraction peak (or prepeak).Comment: 5 pages, 1 figure, An error in the reference (Ref. 7) was correcte
Cellular senescence induced by aberrant MAD2 levels impacts on paclitaxel responsiveness in vitro
Modulational instability in periodic quadratic nonlinear materials
We investigate the modulational instability of plane waves in quadratic
nonlinear materials with linear and nonlinear quasi-phase-matching gratings.
Exact Floquet calculations, confirmed by numerical simulations, show that the
periodicity can drastically alter the gain spectrum but never completely
removes the instability. The low-frequency part of the gain spectrum is
accurately predicted by an averaged theory and disappears for certain gratings.
The high-frequency part is related to the inherent gain of the homogeneous
non-phase-matched material and is a consistent spectral feature.Comment: 4 pages, 7 figures corrected minor misprint
Study of ultrathin Pt/Co/Pt trilayers modified by nanosecond XUV pulses from laser-driven plasma source
We have studied the structural mechanisms responsible for the magnetic reorientation between in-plane and out-of-plane magnetization in the (25 nm Pt)/(3 and 10 nm Co)/(3 nm Pt) trilayer systems irradiated with nanosecond XUV pulses generated with laser-driven gas-puff target plasma source of a narrow continuous spectrum peaked at wavelength of 11 nm. The thickness of individual layers, their density, chemical composition and irradiation-induced lateral strain were deduced from symmetric and asymmetric X-ray diffraction (XRD) patterns, grazing-incidence X-ray reflectometry (GIXR), grazing incidence X-ray fluorescence (GIXRF), extended X-ray absorption fine structure (EXAFS) and transmission electron microscopy (TEM) measurements. In the as grown samples we found, that the Pt buffer layers are relaxed and that the layer interfaces are sharp. As a result of a quasi-uniform irradiation of the samples, the XRD, EXAFS, GIXR and GIXRF data reveal the formation of two distinct layers composed of Pt1-xCox alloys with different Co concentrations, dependent on the thickness of the as grown magnetic Co film but with similar âŒ1% lateral tensile residual strain. For smaller exposure dose (lower number of accumulated pulses) only partial interdiffusion at the interfaces takes place with the formation of a tri-layer composed of Co-Pt alloy sandwiched between thinned Pt layers, as revealed by TEM. The structural modifications are accompanied by magnetization changes, evidenced by means of magneto-optical microscopy. The difference in magnetic properties of the irradiated samples can be related to their modification in Pt1-xCox alloy composition, as the other parameters (lateral strain and alloy thickness) remain almost unchanged. The out-of-plane magnetization observed for the sample with initially 3 nm Co layer can be due to a significant reduction of demagnetization factor resulting from a lower Co concentration
Photoinduced IR absorption in (La(1-x)Sr(x)Mn)(1-\delta)O3: changes of the anti-Jahn-Teller polaron binding energy with doping
Photoinduced IR absorption was measured in (La(1-x)Sr(x)Mn)(1-\delta)O3. A
midinfrared peak centered at ~ 5000 cm was observed in the x=0
antiferromagnetic sample. The peak diminishes and softens as hole doping is
increased. The origin of the photoinduced absorption peak is atributted to the
photon assisted hopping of anti-Jahn-Teller polarons formed by photoexcited
charge carriers, whose binding energy decreases with increasing hole doping.
The shape of the peak indicates that the polarons are small.Comment: 5 pages, 3 figures, submitted to PR
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