5,989 research outputs found
Renormalization-Group Analysis of Layered Sine-Gordon Type Models
We analyze the phase structure and the renormalization group (RG) flow of the
generalized sine-Gordon models with nonvanishing mass terms, using the
Wegner-Houghton RG method in the local potential approximation. Particular
emphasis is laid upon the layered sine-Gordon (LSG) model, which is the
bosonized version of the multi-flavour Schwinger model and approaches the sum
of two ``normal'', massless sine-Gordon (SG) models in the limit of a vanishing
interlayer coupling J. Another model of interest is the massive sine-Gordon
(MSG) model. The leading-order approximation to the UV (ultra-violet) RG flow
predicts two phases for the LSG as well as for the MSG, just as it would be
expected for the SG model, where the two phases are known to be separated by
the Coleman fixed point. The presence of finite mass terms (for the LSG and the
MSG) leads to corrections to the UV RG flow, which are naturally identified as
the ``mass corrections''. The leading-order mass corrections are shown to have
the following consequences: (i) for the MSG model, only one phase persists, and
(ii) for the LSG model, the transition temperature is modified. Within the
mass-corrected UV scaling laws, the limit of J -> 0 is thus nonuniform with
respect to the phase structure of the model. The modified phase structure of
general massive sine-Gordon models is connected with the breaking of symmetries
in the internal space spanned by the field variables. For the LSG, the
second-order subleading mass corrections suggest that there exists a cross-over
regime before the IR scaling sets in, and the nonlinear terms show explicitly
that higher-order Fourier modes appear in the periodic blocked potential.Comment: 27 pages, 7 figure
Strangeness and Chiral Symmetry Breaking
The implications of chiral symmetry breaking and SU(3) symmetry breaking have
been studied in the chiral constituent quark model (CQM). The role of
hidden strangeness component has been investigated for the scalar matrix
elements of the nucleon with an emphasis on the meson-nucleon sigma terms. The
CQM is able to give a qualitative and quantitative description of the
"quark sea" generation through chiral symmetry breaking. The significant
contribution of the strangeness is consistent with the recent available
experimental observations.Comment: 10 pages, 1 table. To appear in Mod. Phys. Lett.
Inhibition of Nonsense-Mediated mRNA Decay by Antisense Morpholino Oligonucleotides Restores Functional Expression of hERG Nonsense and Frameshift Mutations in Long-QT Syndrome
Mutations in the human ether-a-go-go-related gene (hERG) cause long-QT syndrome type 2 (LQT2). We previously described a homozygous LQT2 nonsense mutation Q1070X in which the mutant mRNA is degraded by nonsense-mediated mRNA decay (NMD) leading to a severe clinical phenotype. The degradation of the Q1070X transcript precludes the expression of truncated but functional mutant channels. In the present study, we tested the hypothesis that inhibition of NMD can restore functional expression of LQT2 mutations that are targeted by NMD. We showed that inhibition of NMD by RNA interference-mediated knockdown of UPF1 increased Q1070X mutant channel protein expression and hERG current amplitude. More importantly, we found that specific inhibition of downstream intron splicing by antisense morpholino oligonucleotides prevented NMD of the Q1070X mutant mRNA and restored the expression of functional Q1070X mutant channels. The restoration of functional expression by antisense morpholino oligonucleotides was also observed in LQT2 frameshift mutations. Our findings suggest that inhibition of NMD by antisense morpholino oligonucleotides may be a potential therapeutic approach for some LQT2 patients carrying nonsense and frameshift mutations
UTJECAJ UVJETA POSTUPKA DOBIVANJA MLJEVENE TROSKE TALJENJEM UGLJENA U VISOKOJ PEĆI UZ UPORABU GEOPOLIMERA
In this study, the material characterization of Vietnamese ground coal slag and ground granulated blast furnace slag (GGBFS), such as particle size distribution, chemical composition, bulk density and particle density are shown. The geopolymer specimens were prepared by mixing an 80 m/m% mass of solid materials (ground coal slag and GGBFS in a different ratio) with 20 m/m % of a 10M NaOH alkaline activator. A systematic experimental series was carried out in order to optimize the preparation process. In that series, the heat curing temperature was 60°C for 6 hours, and then selected specimens were heat treated at a high temperature (1000 °C) for 1 hour. After 7 days of ageing, the physical properties of the geopolymer (compressive strength, specimen density) were measured. Also, after 180 days of ageing, the pH values of water in the geopolymer leaching preparation were determined. The results show that the geopolymer can be used for refractory applications due to its good heat resistance properties. However, geopolymers that were heated at 1000 °C had lower compressive strength, specimen density and pH values of water containing the geopolymer than those that were cured at 60 °C.U ovome istraživanju donose se obilježja vijetnamskih granulata ugljene troske i troske željezne rude na osnovi njihove veličine, kemijskoga sastava i gustoće. Uzorci geopolimera pripremljeni su miješanjem 80 % m/m (mase otopljenoga / masa otopine) ugljene i željezne troske (u različitim omjerima) s 20 % m/m 10M NaOH kao alkalnoga aktivatora. Sustavnim serijama eksperimenata optimiziran je postupak pripreme, pri čemu je temperatura iznosila 60 °C tijekom 6 sati, nakon čega su odabrani uzorci zagrijavani 1 sat na 1000 °C. Nakon sljedećih 7 dana izmjerena su fizička svojstva geopolimera (tlačna čvrstoća, gustoća). Zatim je poslije 180 dana određena pH-vrijednost vode korištene u postupku ispiranja geopolimera. Rezultati su pokazali kako geopolimeri mogu biti korišteni za namjene u vatrostalnim uvjetima zahvaljujući toplinskim svojstvima. Također, geopolimeri koji su zagrijavani na 1000 °C imaju niže vrijednosti tlačne čvrstoće, gustoće i pH-vrijednosti vode u njima od onih koji su grijani na 60 °C
DIAL 2004 Working Group Report on Acquisition Quality Control
This report summarizes the discussions of the Working Group on Acquisition Quality at the International Workshop on Document Image Analysis for Libraries, Palo Alto, CA, 23-24 January 2004. Acquisition of the image is one of the most time intensive components of forming a digital library, and the quality of the acquisition will affect all later stages of the digital library project. The current state of the art in acquisition is analyzed. Problems and suggested improvements for image acquisition and storage formats and the special problems associated with acquisition from microfilm follows. A list of general suggestions was developed which was complemented by a wish list of things the Working Group would like to see followed in acquisition discussions in the future
Comparison of Chimerism and Minimal Residual Disease Monitoring for Relapse Prediction after Allogeneic Stem Cell Transplantation for Adult Acute Lymphoblastic Leukemia
AbstractLittle data are available on the relative merits of chimerism and minimal residual disease (MRD) monitoring for relapse prediction after allogeneic hematopoietic stem cell transplantation (HCT). We performed a retrospective analysis of serial chimerism assessments in 101 adult HCT recipients with acute lymphoblastic leukemia (ALL) and of serial MRD assessments in a subgroup of 22 patients. All patients had received myeloablative conditioning. The cumulative incidence of relapse was significantly higher in the patients with increasing mixed chimerism (in-MC) compared with those with complete chimerism, low-level MC, and decreasing MC, but the sensitivity of in-MC detection with regard to relapse prediction was only modest. In contrast, MRD assessment was highly sensitive and specific. Patients with MRD positivity after HCT had the highest incidence of relapse among all prognostic groups analyzed. The median time from MRD positivity to relapse was longer than the median time from detection of in-MC, but in some cases in-MC preceded MRD positivity. We conclude that MRD assessment is a powerful prognostic tool that should be included in the routine post-transplantation monitoring of patients with ALL, but chimerism analysis may provide additional information in some cases. Integration of these tools and clinical judgment should allow optimal decision making with regard to post-transplantation therapeutic interventions
Herschel observations of interstellar chloronium
Using the Herschel Space Observatory's Heterodyne Instrument for the
Far-Infrared (HIFI), we have observed para-chloronium (H2Cl+) toward six
sources in the Galaxy. We detected interstellar chloronium absorption in
foreground molecular clouds along the sight-lines to the bright submillimeter
continuum sources Sgr A (+50 km/s cloud) and W31C. Both the para-H2-35Cl+ and
para-H2-37Cl+ isotopologues were detected, through observations of their
1(11)-0(00) transitions at rest frequencies of 485.42 and 484.23 GHz,
respectively. For an assumed ortho-to-para ratio of 3, the observed optical
depths imply that chloronium accounts for ~ 4 - 12% of chlorine nuclei in the
gas phase. We detected interstellar chloronium emission from two sources in the
Orion Molecular Cloud 1: the Orion Bar photodissociation region and the Orion
South condensation. For an assumed ortho-to-para ratio of 3 for chloronium, the
observed emission line fluxes imply total beam-averaged column densities of ~
2.0E+13 cm-2 and ~ 1.2E+13 cm-2, respectively, for chloronium in these two
sources. We obtained upper limits on the para-H2-35Cl+ line strengths toward H2
Peak 1 in the Orion Molecular cloud and toward the massive young star AFGL
2591. The chloronium abundances inferred in this study are typically at least a
factor ~10 larger than the predictions of steady-state theoretical models for
the chemistry of interstellar molecules containing chlorine. Several
explanations for this discrepancy were investigated, but none has proven
satisfactory, and thus the large observed abundances of chloronium remain
puzzling.Comment: Accepted for publication in the Astrophysical Journa
An extensive photometric study of the Blazhko RR Lyrae star DM Cyg
DM Cyg, a fundamental mode RRab star was observed in the 2007 and 2008
seasons in the frame of the Konkoly Blazhko Survey. Very small amplitude light
curve modulation was detected with 10.57 d modulation period. The maximum
brightness and phase variations do not exceed 0.07 mag and 7 min, respectively.
In spite of the very small amplitude of the modulation, beside the frequency
triplets characterizing the Fourier spectrum of the light curve two quintuplet
components were also identified. The accuracy and the good phase coverage of
our observations made it possible to analyse the light curves at different
phases of the modulation separately. Utilizing the IP method (S\'odor, Jurcsik
and Szeidl, 2009) we could detect very small systematic changes in the global
mean physical parameters of DM Cyg during its Blazhko cycle. The detected
changes are similar to what we have already found for a large modulation
amplitude Blazhko variable MW Lyrae. The amplitudes of the detected changes in
the physical parameters of DM Cyg are only about 10% of that what have been
found in MW Lyr. This is in accordance with its small modulation amplitude
being about one tenth of the modulation amplitude of MW Lyr.Comment: 12 pages, 15 figures, 4 tables. Table 1 is available electronically
eg., from our website: http://www.konkoly.hu/24/publications/. Accepted for
publication in MNRA
Spinal Inhibition of GABAB Receptors by the Extracellular Matrix Protein Fibulin-2 in Neuropathic Rats
In the central nervous system, the inhibitory GABAB receptor is the archetype of heterodimeric G protein-coupled receptors (GPCRs). Receptor interaction with partner proteins has emerged as a novel mechanism to alter GPCR signaling in pathophysiological conditions. We propose here that GABAB activity is inhibited through the specific binding of fibulin-2, an extracellular matrix protein, to the B1a subunit in a rat model of neuropathic pain. We demonstrate that fibulin-2 hampers GABAB activation, presumably through decreasing agonist-induced conformational changes. Fibulin-2 regulates the GABAB-mediated presynaptic inhibition of neurotransmitter release and weakens the GABAB-mediated inhibitory effect in neuronal cell culture. In the dorsal spinal cord of neuropathic rats, fibulin-2 is overexpressed and colocalized with B1a. Fibulin-2 may thus interact with presynaptic GABAB receptors, including those on nociceptive afferents. By applying anti-fibulin-2 siRNAin vivo, we enhanced the antinociceptive effect of intrathecal baclofen in neuropathic rats, thus demonstrating that fibulin-2 limits the action of GABAB agonistsin vivo. Taken together, our data provide an example of an endogenous regulation of GABAB receptor by extracellular matrix proteins and demonstrate its functional impact on pathophysiological processes of pain sensitization.This work was funded by the ANR ImNet (ANR-07-NEURO015-01). Imaging was performed on the Bordeaux Imaging Center, member of the FranceBioImaging national infrastructure (ANR-10-INBS-04)
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