Search results for "instability"
showing 10 items of 724 documents
Vortex instability and vortex-glass transition in Bi 2 Sr 2 CaCu 2 O 8 and YBa 2 Cu 3 O 7 thin films
2000
We investigated the current-voltage (I-V) curves of high-T c superconductors at very low and very high dissipation levels. In the limit of low driving currents the barriers for vortex movement become infinite in the vortex-glass state. Using long measurement bridges up to 0.5 m we were able to sample an electric field range from 1 V/m down to 10 -8 V/m in one experimental setup. The resulting I-V curves allowed us to verify an excellent glass scaling of the I-V curves, which revealed an increased dynamical exponent of the glass transition. We also found a considerable dependence of the vortex-glass scaling on the probed electric-field range. At very high dissipation levels the I-V curves of…
Stability of an electromagnetically levitated spherical sample in a set of coaxial circular loops
2005
This paper presents a theoretical study of oscillatory and rotational instabilities of a solid spherical body, levitated electromagnetically in axisymmetric coils made of coaxial circular loops. We apply our previous theory to analyze the static and dynamic stability of the sample depending on the ac frequency and the position of the sample in the coils for several simple configurations. We introduce an original analytical approach employing a gauge transformation for the vector potential. First, we calculate the spring constants that define the frequency of small-amplitude oscillations. For static stability, the spring constants must be positive. Dynamic instabilities are characterized by …
Measuring emotional instability, prosocial behavior and aggression in pre-adolescents: A cross-national study
1997
Abstract Three scales measuring emotional instability, prosocial behavior and aggression were analyzed in a new study involving subjects between the ages of 11 and 15 from three different countries: Italy, Hungary and the Czech Republic. Principal component analysis (PCA), simultaneous component analysis (SCA) and congruence coefficients were used to evaluate and compare the factorial structure of the scales in the three different countries. Results clearly show a substantial equivalence of the components in the three countries, attesting to the generalizability of these measures in different cultural contexts. Country comparisons on the mean level of the scales show that Italian boys and g…
Thymidylate synthase polymorphism and microsatellite instability: association in colorectal cancer.
2005
5-Fluorouracil (5FU) is the main drug used for the treatment of colorectal cancer (CRC) and Thymidilate Synthase (TS) is its target enzyme. TS gene has regulatory tandemly repeated sequences in its 5'' and 3''untraslated region (5''-3'' UTR). CRC often shows a kind of genomic instability called Microsatellite Instability (MSI) that is associated with TS levels and survival. Our data show that the genotype 2R/2R (homozygosity for 2 tandem repeat sequences in the 5''UTR) is more frequently associated with MSI+ and lower TS levels. More over we did not find any significant association between the 2R/3R (heterozygosity for 2 and 3 tandem repeat sequences in the 5''UTR) and 3R/3R (homozygosity f…
Dynamical formation of a hairy black hole in a cavity from the decay of unstable solitons
2016
Recent numerical relativity simulations within the Einstein--Maxwell--(charged-)Klein-Gordon (EMcKG) system have shown that the non-linear evolution of a superradiantly unstable Reissner-Nordstr\"om black hole (BH) enclosed in a cavity, leads to the formation of a BH with scalar hair. Perturbative evidence for the stability of such hairy BHs has been independently established, confirming they are the true endpoints of the superradiant instability. The same EMcKG system admits also charged scalar soliton-type solutions, which can be either stable or unstable. Using numerical relativity techniques, we provide evidence that the time evolution of some of these $\textit{unstable}$ solitons leads…
Alternative lengthening of telomeres--an enhanced chromosomal instability in aggressive non-MYCN amplified and telomere elongated neuroblastomas
2010
Telomere length alterations are known to cause genomic instability and influence clinical course in several tumor types, but have been little investigated in neuroblastoma (NB), one of the most common childhood tumors. In the present study, telomere-dependent chromosomal instability and telomere length were determined in six NB cell lines and fifty tumor biopsies. The alternative lengthening of telomeres (ALT) pathway was assayed by scoring ALT-associated promyelocytic leukemia (PML) bodies (APBs). We found a reduced probability of overall survival for tumors with increased telomere length compared to cases with reduced or unchanged telomere length. In non-MYCN amplified tumors, a reduced o…
Biological consequences of tumor hypoxia
2001
Growing evidence from experimental and clinical studies points to the fundamental, pathophysiologic role of hypoxia in solid tumors. Intratumoral hypoxia is a consequence of a structurally and functionally disturbed microcirculation, with deterioration of the diffusion geometry and of tumor-associated anemia. Hypoxia-induced changes of the proteome in the neoplastic and stroma cells may lead to neoplastic growth impairment through molecular mechanisms, resulting in cellular quiescence, differentiation, and apoptosis. Alternatively, hypoxia-induced proteome changes activating nonspecific stress response, anaerobic metabolism, angiogenesis, tissue remodeling, and change of cell contacts may p…
Somatic mutation profiles as molecular classifiers of ulcerative colitis-associated colorectal cancer.
2021
Ulcerative colitis increases colorectal cancer risk by mechanisms that remain incompletely understood. We approached this question by determining the genetic and epigenetic profiles of colitis-associated colorectal carcinomas (CA-CRC). The findings were compared to Lynch syndrome (LS), a different form of cancer predisposition that shares the importance of immunological factors in tumorigenesis. CA-CRCs (n=27) were investigated for microsatellite instability, CpG island methylator phenotype, and somatic mutations of 999 cancer-relevant genes ("Pan-cancer" panel). A subpanel of "Pan-cancer" design (578 genes) was used for LS colorectal tumors (n=28). Mutational loads and signatures stratifie…
Generation of vector dark-soliton trains by induced modulational instability in a highly birefringent fiber
1999
International audience; We present a set of experimental observations that demonstrate the generation of vector trains of dark-soliton pulses in the orthogonal axes of a highly birefringent optical fiber. We generated dark-soliton trains with terahertz repetition rate in the normal group-velocity dispersion regime by inducing a polarization modulational instability by mixing two intense, orthogonal continuous laser beams. Numerical solutions of the propagation equations were used to optimize the emission of vector dark pulses at the fiber output.
Static instability analysis for travelling membranes and plates interacting with axially moving ideal fluid
2010
The out-of-plane instability of a moving plate, travelling between two rollers with constant velocity, is studied, taking into account the mutual interaction between the buckled plate and the surrounding, axially flowing ideal fluid. Transverse displacement of the buckled plate (assumed cylindrical) is described by an integro-differential equation that includes the centrifugal force, the aerodynamic reaction of the external medium, the vertical projection of membrane tension, and the bending force. The aerodynamic reaction is found analytically as a functional of the displacement. To find the critical divergence velocity of the moving plate and its corresponding buckling mode, an eigenvalue…