996 research outputs found
Interacting potential between spinons in the compact QED3 description of the Heisenberg model
We implement a Chern-Simons (CS) contribution into the compact QED3
description of the antiferromagnetic Heisenberg model in two dimensions at zero
temperature. The CS term allows for the conservation of the SU(2) symmetry of
the quantum spin system and fixes the flux through a plaquette to be a multiple
of pi as was shown by Marston. We work out the string tension of the confining
potential which acts between the spinons and show that the CS term induces a
screening effect on the magnetic field only. The confining potential between
spinons is not affected by the CS flux. The strict site-occupation by a single
spin 1/2 is enforced by the introduction of an imaginary chemical potential
constraint.Comment: 8 page
Twist glass transition in regioregulated poly(3-alkylthiophenes)s
The molecular structure and dynamics of regioregulated poly(3-butylthiophene)
(P3BT), poly(3-hexylthiophene)(P3HT), and poly(3-dodecylthiophene) (P3DDT) were
investigated using Fourier transform infrared absorption (FTIR), solid state
C nuclear magnetic resonance (NMR), and differential scanning
calorimetry (DSC) measurements. In the DSC measurements, the endothermic peak
was obtained around 340 K in P3BT, and assigned to enthalpy relaxation that
originated from the glass transition of the thiophene ring twist in crystalline
phase from results of FTIR, C cross-polarization and magic-angle
spinning (CPMAS) NMR, C spin-lattice relaxation time measurements, and
centerband-only detection of exchange (CODEX) measurements. We defined this
transition as {\it twist-glass transition}, which is analogous to the plastic
crystal - glassy crystal transition.Comment: 9 pages, 10 figures, 2 tables. Phys.Rev.B, in pres
Detection of Nav1.5 conformational change in mammalian cells using the non-canonical amino acid ANAP
Nav1.5 inactivation is necessary for healthy conduction of the cardiac action potential. Genetic mutations of Nav1.5 perturb inactivation and cause potentially fatal arrhythmias associated with long QT syndrome type 3. The exact structural dynamics of the inactivation complex is unknown. To sense inactivation gate conformational change in live mammalian cells, we incorporated the solvatochromic fluorescent non-canonical amino acid ANAP into single sites in the Nav1.5 inactivation gate. ANAP was incorporated in full-length and C-terminally truncated Nav1.5 channels using mammalian cell synthetase-tRNA technology. ANAP-incorporated channels were expressed in mammalian cells and they exhibited pathophysiological function. A spectral imaging potassium-depolarization assay was designed to detect ANAP emission shifts associated with Nav1.5 conformational change. Site-specific intracellular ANAP incorporation affords live-cell imaging and detection of Nav1.5 inactivation gate conformational change in mammalian cells
Progress and Trends in Artificial Silk Spinning: A Systematic Review
More than 400 million years of natural selection acting throughout the arthropoda has resulted in highly specialized and energetically efficient processes to produce protein-based fibers with properties that are a source of inspiration for all. As a result, for over 80 years researchers have been inspired by natural silk production in their attempts to spin artificial silks. While significant progress has been made, with fibers now regularly outperforming silkworm silks, surpassing the properties of superior silks, such as spider dragline, is still an area of considerable effort. This review provides an overview of the different approaches for artificial silk fiber spinning and compares all published fiber properties to date which has identified future trends and challenges on the road towards replicating high performance silks
Association between longer hospitalization and development of de novo donor specific antibodies in simultaneous liver–kidney transplant recipients
© 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. Background:De novo Donor Specific Antibodies (DSA) are considered as a risk factor for the kidney allograft outcomes in recipients after simultaneous liver–kidney transplantation (SLKT). We hypothesized that length of hospital stay (LOS) might be associated with de novo DSA development of due to the increased likelihood of receiving blood transfusions with reduced immunosuppressive regimens. Methods: This study is a single-center, retrospective cohort study consisting of 85 recipients who underwent SLKT from 2009 to 2018 in our hospital. We divided the patients into two groups according to LOS [long hospital stay (L) group (LOS \u3e14 days) and short hospital stay (S) group (LOS ≤14 days)]. Propensity score (PS) has been created using logistic regression to predict LOS greater than median of 14 days. The association between the presence of de novo DSA and LOS was assessed by logistic regression models adjusted for PS. Results: The mean age at transplantation of the entire cohort was 55.5 ± 10.1 years. Sixty percent of the recipients were male and Caucasian. Median LOS in (L) group was three-fold longer than (S) group [L: median 30 days (IQR: 21–52), S: median 8.5 days (IQR: 7–11)]. Eight patients developed de novo DSA after SLKT (9.4%), all of them were in (L) group. Longer LOS was significantly associated with higher risk of development of de novo DSA in unadjusted (OR+ each 5 days: 1.09, 95% CI:1.02–1.16) and PS adjusted (OR+ each 5 days: 1.11, 95% CI:1.02–1.21) analysis. Conclusion: Longer hospitalization is significantly associated with the development of de novo DSA in SLKT
Isolation, characterization and comparison of Atlantic and Chinook salmon growth hormone 1 and 2
<p>Abstract</p> <p>Background</p> <p>Growth hormone (GH) is an important regulator of skeletal growth, as well as other adapted processes in salmonids. The GH gene (<it>gh</it>) in salmonids is represented by duplicated, non-allelic isoforms designated as <it>gh1 </it>and <it>gh2</it>. We have isolated and characterized <it>gh</it>-containing bacterial artificial chromosomes (BACs) of both Atlantic and Chinook salmon (<it>Salmo salar </it>and <it>Oncorhynchus tshawytscha</it>) in order to further elucidate our understanding of the conservation and regulation of these loci.</p> <p>Results</p> <p>BACs containing <it>gh1 </it>and <it>gh2 </it>from both Atlantic and Chinook salmon were assembled, annotated, and compared to each other in their coding, intronic, regulatory, and flanking regions. These BACs also contain the genes for skeletal muscle sodium channel oriented in the same direction. The sequences of the genes for interferon alpha-1, myosin alkali light chain and microtubule associated protein Tau were also identified, and found in opposite orientations relative to <it>gh1 </it>and <it>gh2</it>. Viability of each of these genes was examined by PCR. We show that transposon insertions have occurred differently in the promoters of <it>gh</it>, within and between each species. Other differences within the promoters and intronic and 3'-flanking regions of the four <it>gh </it>genes provide evidence that they have distinct regulatory modes and possibly act to function differently and/or during different times of salmonid development.</p> <p>Conclusion</p> <p>A core proximal promoter for transcription of both <it>gh1 </it>and <it>gh2 </it>is conserved between the two species of salmon. Nevertheless, transposon integration and regulatory element differences do exist between the promoters of <it>gh1 </it>and <it>gh2</it>. Additionally, organization of transposon families into the BACs containing <it>gh1 </it>and for the BACs containing <it>gh2</it>, are very similar within orthologous regions, but much less clear conservation is apparent in comparisons between the <it>gh1</it>- and <it>gh2</it>-containing paralogous BACs for the two fish species. This is consistent with the hypothesis that a burst of transposition activity occurred during the speciation events which led to Atlantic and Pacific salmon. The Chinook and other <it>Oncorhynchus </it>GH1s are strikingly different in comparison to the other GHs and this change is not apparent in the surrounding non-coding sequences.</p
Original observations of Desmozoon lepeophtherii, a microsporidian hyperparasite infecting the salmon louse Lepeophtheirus salmonis, and its subsequent detection by other researchers
A microsporidian hyperparasite, Desmozoon lepeophtherii, of the parasitic copepod Lepeophtheirus salmonis (salmon louse), infecting farmed Atlantic salmon (Salmo salar), was first discovered in the west of Scotland in 2000. Heavily infected salmon lice are easily recognised as they have large opaque inclusions distributed throughout the body. The prevalence of salmon lice with visible signs of microsporidiosis can be up to 10% of the population from certain farm sites. The microsporidian was also isolated from the host Atlantic salmon suggesting it may have a two host life cycle. The authors believe that the infection in immunocompetent salmon may be latent, becoming acute during periods of infection with another pathogen or during sexual maturation. Since its first discovery in Scotland, Desmozoon lepeophtherii has been subsequently reported from Norway, and more recently from the Pacific coast of North America
Fresnel lens sidewall design for imaging optics
We developed a ray tracing simulation tool for imaging systems including a Fresnel lens with a quasi-arbitrary sidewall structure. One issue with Fresnel lens is that noise in the image plane can appear from rays passing through or reflected at its sidewalls. One way to reduce it is to modify the orientation of the sidewalls so that rays will not reach the image plane. To find the best sidewall orientations, we developed a method where locally, a sidewall can freely be oriented. We could then derive the best modulation scheme for each Fresnel lens sidewall. In the case of a single imaging Fresnel lens, relative parasite noise intensity could mostly be prevented. To experimentally check our method, snapshot images were taken with single Fresnel lenses and a single spherical lens. No noticeable differences in image quality could be observed using a standard C-MOS camera. However, parasite noise could experimentally be detected with a Fresnel lens prototype when using a very high-dynamic range C-MOS camera
FAS-dependent cell death in α-synuclein transgenic oligodendrocyte models of multiple system atrophy
Multiple system atrophy is a parkinsonian neurodegenerative disorder. It is cytopathologically characterized by accumulation of the protein p25α in cell bodies of oligodendrocytes followed by accumulation of aggregated α-synuclein in so-called glial cytoplasmic inclusions. p25α is a stimulator of α-synuclein aggregation, and coexpression of α-synuclein and p25α in the oligodendroglial OLN-t40-AS cell line causes α-synuclein aggregate-dependent toxicity. In this study, we investigated whether the FAS system is involved in α-synuclein aggregate dependent degeneration in oligodendrocytes and may play a role in multiple system atrophy. Using rat oligodendroglial OLN-t40-AS cells we demonstrate that the cytotoxicity caused by coexpressing α-synuclein and p25α relies on stimulation of the death domain receptor FAS and caspase-8 activation. Using primary oligodendrocytes derived from PLP-α-synuclein transgenic mice we demonstrate that they exist in a sensitized state expressing pro-apoptotic FAS receptor, which makes them sensitive to FAS ligand-mediated apoptosis. Immunoblot analysis shows an increase in FAS in brain extracts from multiple system atrophy cases. Immunohistochemical analysis demonstrated enhanced FAS expression in multiple system atrophy brains notably in oligodendrocytes harboring the earliest stages of glial cytoplasmic inclusion formation. Oligodendroglial FAS expression is an early hallmark of oligodendroglial pathology in multiple system atrophy that mechanistically may be coupled to α-synuclein dependent degeneration and thus represent a potential target for protective intervention
- …