Intermediate Filaments Play a Pivotal Role in Regulating Cell Architecture and Function.

Science.gov (United States)

Lowery, Jason; Kuczmarski, Edward R; Herrmann, Harald; Goldman, Robert D

2015-07-10

Intermediate filaments (IFs) are composed of one or more members of a large family of cytoskeletal proteins, whose expression is cell- and tissue type-specific. Their importance in regulating the physiological properties of cells is becoming widely recognized in functions ranging from cell motility to signal transduction. IF proteins assemble into nanoscale biopolymers with unique strain-hardening properties that are related to their roles in regulating the mechanical integrity of cells. Furthermore, mutations in the genes encoding IF proteins cause a wide range of human diseases. Due to the number of different types of IF proteins, we have limited this short review to cover structure and function topics mainly related to the simpler homopolymeric IF networks composed of vimentin, and specifically for diseases, the related muscle-specific desmin IF networks. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Intermediate filament protein evolution and protists.

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Preisner, Harald; Habicht, Jörn; Garg, Sriram G; Gould, Sven B

2018-03-23

Metazoans evolved from a single protist lineage. While all eukaryotes share a conserved actin and tubulin-based cytoskeleton, it is commonly perceived that intermediate filaments (IFs), including lamin, vimentin or keratin among many others, are restricted to metazoans. Actin and tubulin proteins are conserved enough to be detectable across all eukaryotic genomes using standard phylogenetic methods, but IF proteins, in contrast, are notoriously difficult to identify by such means. Since the 1950s, dozens of cytoskeletal proteins in protists have been identified that seemingly do not belong to any of the IF families described for metazoans, yet, from a structural and functional perspective fit criteria that define metazoan IF proteins. Here, we briefly review IF protein discovery in metazoans and the implications this had for the definition of this protein family. We argue that the many cytoskeletal and filament-forming proteins of protists should be incorporated into a more comprehensive picture of IF evolution by aligning it with the recent identification of lamins across the phylogenetic diversity of eukaryotic supergroups. This then brings forth the question of how the diversity of IF proteins has unfolded. The evolution of IF proteins likely represents an example of convergent evolution, which, in combination with the speed with which these cytoskeletal proteins are evolving, generated their current diversity. IF proteins did not first emerge in metazoa, but in protists. Only the emergence of cytosolic IF proteins that appear to stem from a nuclear lamin is unique to animals and coincided with the emergence of true animal multicellularity. © 2018 Wiley Periodicals, Inc.

Expression of the type VI intermediate filament proteins CP49 and filensin in the mouse lens epithelium.

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FitzGerald, Paul; Sun, Ning; Shibata, Brad; Hess, John F

2016-01-01

The differentiated lens fiber cell assembles a filamentous cytoskeletal structure referred to as the beaded filament (BF). The BF requires CP49 (bfsp2) and filensin (bfsp1) for assembly, both of which are highly divergent members of the large intermediate filament (IF) family of proteins. Thus far, these two proteins have been reported only in the differentiated lens fiber cell. For this reason, both proteins have been considered robust markers of fiber cell differentiation. We report here that both proteins are also expressed in the mouse lens epithelium, but only after 5 weeks of age. Localization of CP49 was achieved with immunocytochemical probing of wild-type, CP49 knockout, filensin knockout, and vimentin knockout mice, in sections and in the explanted lens epithelium, at the light microscope and electron microscope levels. The relationship between CP49 and other cytoskeletal elements was probed using fluorescent phalloidin, as well as with antibodies to vimentin, GFAP, and α-tubulin. The relationship between CP49 and the aggresome was probed with antibodies to γ-tubulin, ubiquitin, and HDAC6. CP49 and filensin were expressed in the mouse lens epithelium, but only after 5 weeks of age. At the light microscope level, these two proteins colocalize to a large tubular structure, approximately 7 × 1 μm, which was typically present at one to two copies per cell. This structure is found in the anterior and anterolateral lens epithelium, including the zone where mitosis occurs. The structure becomes smaller and largely undetectable closer to the equator where the cell exits the cell cycle and commits to fiber cell differentiation. This structure bears some resemblance to the aggresome and is reactive with antibodies to HDAC6, a marker for the aggresome. However, the structure does not colocalize with antibodies to γ-tubulin or ubiquitin, also markers for the aggresome. The structure also colocalizes with actin but appears to largely exclude vimentin and �

Intermediate filaments and gene regulation.

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Traub, P

1995-01-01

The biological role of intermediate filaments (IFs) of eukaryotic cells is still a matter of conjecture. On the basis of immunofluorescence and electron microscopic observations, they appear to play a cytoskeletal role in that they stabilize cellular structure and organize the distribution and interactions of intracellular organelles and components. The expression of a large number of cell type-specific and developmentally regulated subunit proteins is believed to provide multicellular organisms with different IF systems capable of differential interactions with the various substructures and components of their multiple, differentiated cells. However, the destruction of distinct IF systems by manipulation of cultured cells or by knock-out mutation of IF subunit proteins in transgenic mice exerts relatively little influence on cellular morphology and physiology and on development of mutant animals. In order to rationalize this dilemma, the cytoskeletal concept of IF function has been extended to purport that cytoplasmic (c) IFs and their subunit proteins also play fundamental roles in gene regulation. It is based on the in vitro capacity of cIF(protein)s to interact with guanine-rich, single-stranded DNA, supercoiled DNA and histones, as well as on their close structural relatedness to gene-regulatory DNA-binding and nuclear matrix proteins. Since cIF proteins do not possess classical nuclear localization signals, it is proposed that cIFs directly penetrate the double nuclear membrane, exploiting the amphiphilic, membrane-active character of their subunit proteins. Since they can establish metastable multisite contacts with nuclear matrix structures and/or chromatin areas containing highly repetitive DNA sequence elements at the nuclear periphery, they are supposed to participate in chromosome distribution and chromatin organization in interphase nuclei of differentiated cells. Owing to their different DNA-binding specificities, the various cIF systems may in this

Fingerprinting taste buds: intermediate filaments and their implication for taste bud formation.

OpenAIRE

Witt, M; Reutter, K; Ganchrow, D; Ganchrow, J R

2000-01-01

Intermediate filaments in taste organs of terrestrial (human and chick) as well as aquatic (Xenopus laevis) species were detected using immunohistochemistry and electron microscopy. During development, the potential importance of the interface between the taste bud primordium and non-gustatory adjacent tissues is evidenced by the distinct immunoreactivity of a subpopulation of taste bud cells for cytokeratins and vimentin. In human foetuses, the selective molecular marker for taste bud primor...

Electron microscopy of intermediate filaments: teaming up with atomic force and confocal laser scanning microscopy.

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Kreplak, Laurent; Richter, Karsten; Aebi, Ueli; Herrmann, Harald

2008-01-01

Intermediate filaments (IFs) were originally discovered and defined by electron microscopy in myoblasts. In the following it was demonstrated and confirmed that they constitute, in addition to microtubules and microfilaments, a third independent, general filament system in the cytoplasm of most metazoan cells. In contrast to the other two systems, IFs are present in cells in two principally distinct cytoskeletal forms: (i) extended and free-running filament arrays in the cytoplasm that are integrated into the cytoskeleton by associated proteins of the plakin type; and (ii) a membrane- and chromatin-bound thin 'lamina' of a more or less regular network of interconnected filaments made from nuclear IF proteins, the lamins, which differ in several important structural aspects from cytoplasmic IF proteins. In man, more than 65 genes code for distinct IF proteins that are expressed during embryogenesis in various routes of differentiation in a tightly controlled manner. IF proteins exhibit rather limited sequence identity implying that the different types of IFs have distinct biochemical properties. Hence, to characterize the structural properties of the various IFs, in vitro assembly regimes have been developed in combination with different visualization methods such as transmission electron microscopy of fixed and negatively stained samples as well as methods that do not use staining such as scanning transmission electron microscopy (STEM) and cryoelectron microscopy as well as atomic force microscopy. Moreover, with the generation of both IF-type specific antibodies and chimeras of fluorescent proteins and IF proteins, it has become possible to investigate the subcellular organization of IFs by correlative fluorescence and electron microscopic methods. The combination of these powerful methods should help to further develop our understanding of nuclear architecture, in particular how nuclear subcompartments are organized and in which way lamins are involved.

Intermediate filaments in smooth muscle from pregnant and non-pregnant human uterus.

OpenAIRE

Leoni, P; Carli, F; Halliday, D

1990-01-01

The intermediate filament proteins desmin and vimentin from pregnant and non-pregnant uterine muscle and smooth-muscle cells in culture were analysed using SDS/PAGE. The desmin content in uterine muscle increases dramatically during pregnancy, whereas vimentin remains unchanged or changes very little. When muscle cells are kept in culture, a considerable increase in vimentin content is observed as compared with vimentin in freshly isolated non-pregnant uterine tissue. Our results strengthen t...

Heterologous expression of cellobiohydrolases in filamentous fungi

DEFF Research Database (Denmark)

Zoglowek, Marta; Lübeck, Peter S.; Ahring, Birgitte K.

2015-01-01

Cellobiohydrolases are among the most important enzymes functioning in the hydrolysis of crystalline cellulose, significantly contributing to the efficient biorefining of recalcitrant lignocellulosic biomass into biofuels and bio-based products. Filamentous fungi are recognized as both well...... into valuable products. However, due to low cellobiohydrolase activities, certain fungi might be deficient with regard to enzymes of value for cellulose conversion, and improving cellobiohydrolase expression in filamentous fungi has proven to be challenging. In this review, we examine the effects of altering...... promoters, signal peptides, culture conditions and host post-translational modifications. For heterologous cellobiohydrolase production in filamentous fungi to become an industrially feasible process, the construction of site-integrating plasmids, development of protease-deficient strains and glycosylation...

Heterologous gene expression in filamentous fungi.

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Su, Xiaoyun; Schmitz, George; Zhang, Meiling; Mackie, Roderick I; Cann, Isaac K O

2012-01-01

Filamentous fungi are critical to production of many commercial enzymes and organic compounds. Fungal-based systems have several advantages over bacterial-based systems for protein production because high-level secretion of enzymes is a common trait of their decomposer lifestyle. Furthermore, in the large-scale production of recombinant proteins of eukaryotic origin, the filamentous fungi become the vehicle of choice due to critical processes shared in gene expression with other eukaryotic organisms. The complexity and relative dearth of understanding of the physiology of filamentous fungi, compared to bacteria, have hindered rapid development of these organisms as highly efficient factories for the production of heterologous proteins. In this review, we highlight several of the known benefits and challenges in using filamentous fungi (particularly Aspergillus spp., Trichoderma reesei, and Neurospora crassa) for the production of proteins, especially heterologous, nonfungal enzymes. We review various techniques commonly employed in recombinant protein production in the filamentous fungi, including transformation methods, selection of gene regulatory elements such as promoters, protein secretion factors such as the signal peptide, and optimization of coding sequence. We provide insights into current models of host genomic defenses such as repeat-induced point mutation and quelling. Furthermore, we examine the regulatory effects of transcript sequences, including introns and untranslated regions, pre-mRNA (messenger RNA) processing, transcript transport, and mRNA stability. We anticipate that this review will become a resource for researchers who aim at advancing the use of these fascinating organisms as protein production factories, for both academic and industrial purposes, and also for scientists with general interest in the biology of the filamentous fungi. Copyright © 2012 Elsevier Inc. All rights reserved.

Lessons from Animal Models of Cytoplasmic Intermediate Filament Proteins.

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Bouameur, Jamal-Eddine; Magin, Thomas M

Cytoplasmic intermediate filaments (IFs) represent a major cytoskeletal network contributing to cell shape, adhesion and migration as well as to tissue resilience and renewal in numerous bilaterians, including mammals. The observation that IFs are dispensable in cultured mammalian cells, but cause tissue-specific, life-threatening disorders, has pushed the need to investigate their function in vivo. In keeping with human disease, the deletion or mutation of murine IF genes resulted in highly specific pathologies. Epidermal keratins, together with desmin, are essential to protect corresponding tissues against mechanical force but also participate in stabilizing cell adhesion and in inflammatory signalling. Surprisingly, other IF proteins contribute to tissue integrity to a much lesser extent than anticipated, pointing towards their role in stress situations. In support, the overexpression of small chaperones or the interference with inflammatory signalling in several settings has been shown to rescue severe tissue pathologies that resulted from the expression of mutant IF proteins. It stills remains an open issue whether the wide range of IF disorders share similar pathomechanisms. Moreover, we lack an understanding how IF proteins participate in signalling processes. Now, with a large number of mouse models in hand, the next challenge will be to develop organotypic cell culture models to dissect pathomechanisms at the molecular level, to employ Crispr/Cas-mediated genome engineering to optimize models and, finally, to combine available animal models with medicinal chemistry for the development of molecular therapies.

Airborne acrolein induces keratin-8 (Ser-73) hyperphosphorylation and intermediate filament ubiquitination in bronchiolar lung cell monolayers.

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Burcham, Philip C; Raso, Albert; Henry, Peter J

2014-05-07

The combustion product acrolein is a key mediator of pulmonary edema in victims of smoke inhalation injury. Since studying acrolein toxicity in conventional in vitro systems is complicated by reactivity with nucleophilic culture media constituents, we explored an exposure system which delivers airborne acrolein directly to lung cell monolayers at the air-liquid interface. Calu-3 lung adenocarcinoma cells were maintained on membrane inserts such that the basal surface was bathed in nucleophile-free media while the upper surface remained in contact with acrolein-containing air. Cells were exposed to airborne acrolein for 30 min before they were allowed to recover in fresh media, with cell sampling at defined time points to allow evaluation of toxicity and protein damage. After prior exposure to acrolein, cell ATP levels remained close to controls for 4h but decreased in an exposure-dependent manner by 24h. A loss of transepithelial electrical resistance and increased permeability to fluorescein isothiocyanate-labeled dextran preceded ATP loss. Use of antibody arrays to monitor protein expression in exposed monolayers identified strong upregulation of phospho-keratin-8 (Ser(73)) as an early consequence of acrolein exposure. These changes were accompanied by chemical damage to keratin-8 and other intermediate filament family members, while acrolein exposure also resulted in controlled ubiquitination of high mass proteins within the intermediate filament extracts. These findings confirm the usefulness of systems allowing delivery of airborne smoke constituents to lung cell monolayers during studies of the molecular basis for acute smoke intoxication injury. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Biological adhesion of the flatworm Macrostomum lignano relies on a duo-gland system and is mediated by a cell type-specific intermediate filament protein.

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Lengerer, Birgit; Pjeta, Robert; Wunderer, Julia; Rodrigues, Marcelo; Arbore, Roberto; Schärer, Lukas; Berezikov, Eugene; Hess, Michael W; Pfaller, Kristian; Egger, Bernhard; Obwegeser, Sabrina; Salvenmoser, Willi; Ladurner, Peter

2014-02-12

Free-living flatworms, in both marine and freshwater environments, are able to adhere to and release from a substrate several times within a second. This reversible adhesion relies on adhesive organs comprised of three cell types: an adhesive gland cell, a releasing gland cell, and an anchor cell, which is a modified epidermal cell responsible for structural support. However, nothing is currently known about the molecules that are involved in this adhesion process. In this study we present the detailed morphology of the adhesive organs of the free-living marine flatworm Macrostomum lignano. About 130 adhesive organs are located in a horse-shoe-shaped arc along the ventral side of the tail plate. Each organ consists of exactly three cells, an adhesive gland cell, a releasing gland cell, and an anchor cell. The necks of the two gland cells penetrate the anchor cell through a common pore. Modified microvilli of the anchor cell form a collar surrounding the necks of the adhesive- and releasing glands, jointly forming the papilla, the outer visible part of the adhesive organs. Next, we identified an intermediate filament (IF) gene, macif1, which is expressed in the anchor cells. RNA interference mediated knock-down resulted in the first experimentally induced non-adhesion phenotype in any marine animal. Specifically, the absence of intermediate filaments in the anchor cells led to papillae with open tips, a reduction of the cytoskeleton network, a decline in hemidesmosomal connections, and to shortened microvilli containing less actin. Our findings reveal an elaborate biological adhesion system in a free-living flatworm, which permits impressively rapid temporary adhesion-release performance in the marine environment. We demonstrate that the structural integrity of the supportive cell, the anchor cell, is essential for this adhesion process: the knock-down of the anchor cell-specific intermediate filament gene resulted in the inability of the animals to adhere. The RNAi

[The effect of hyperthyroidism on the cognition processes and the state of the glial intermediate filaments in the rat brain].

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Nedzvets'kyĭ, V S; Nerush, P O

2010-01-01

The effects of hyperthyreosis on oxidative stress, state of glial intermediate filaments and memory were investigated. We observed a significant increase in lipid peroxidation products into both hippocampus and cortex and memory worsening. The changes of GFAP polypeptides was observed in hippocampus and cortex. In group of rats with hyperthyreosis, the content of GFAP in both soluble and filamentous fractions was increased in hippocampus. This data shows, that glial cytoskeleton is reconstructed under thyroid hormone effects.

Plectin isoforms as organizers of intermediate filament cytoarchitecture.

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Wiche, Gerhard; Winter, Lilli

2011-01-01

Intermediate filaments (IFs) form cytoplamic and nuclear networks that provide cells with mechanical strength. Perturbation of this structural support causes cell and tissue fragility and accounts for a number of human genetic diseases. In recent years, important additional roles, nonmechanical in nature, were ascribed to IFs, including regulation of signaling pathways that control survival and growth of the cells, and vectorial processes such as protein targeting in polarized cellular settings. The cytolinker protein plectin anchors IF networks to junctional complexes, the nuclear envelope and cytoplasmic organelles and it mediates their cross talk with the actin and tubulin cytoskeleton. These functions empower plectin to wield significant influence over IF network cytoarchitecture. Moreover, the unusual diversity of plectin isoforms with different N termini and a common IF-binding (C-terminal) domain enables these isoforms to specifically associate with and thereby bridge IF networks to distinct cellular structures. Here we review the evidence for IF cytoarchitecture being controlled by specific plectin isoforms in different cell systems, including fibroblasts, endothelial cells, lens fibers, lymphocytes, myocytes, keratinocytes, neurons and astrocytes, and discuss what impact the absence of these isoforms has on IF cytoarchitecture-dependent cellular functions.

Checkpoint kinase 1-induced phosphorylation of O-linked β-N-acetylglucosamine transferase regulates the intermediate filament network during cytokinesis.

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Li, Zhe; Li, Xueyan; Nai, Shanshan; Geng, Qizhi; Liao, Ji; Xu, Xingzhi; Li, Jing

2017-12-01

Checkpoint kinase 1 (Chk1) is a kinase instrumental for orchestrating DNA replication, DNA damage checkpoints, the spindle assembly checkpoint, and cytokinesis. Despite Chk1's pivotal role in multiple cellular processes, many of its substrates remain elusive. Here, we identified O- linked β- N -acetylglucosamine ( O -GlcNAc)-transferase (OGT) as one of Chk1's substrates. We found that Chk1 interacts with and phosphorylates OGT at Ser-20, which not only stabilizes OGT, but also is required for cytokinesis. Phospho-specific antibodies of OGT-pSer-20 exhibited specific signals at the midbody of the cell, consistent with midbody localization of OGT as reported previously. Moreover, phospho-deficient OGT (S20A) cells attenuated cellular O -GlcNAcylation levels and also reduced phosphorylation of Ser-71 in the cytoskeletal protein vimentin, a modification critical for severing vimentin filament during cytokinesis. Consequently, elongated vimentin bridges were observed in cells depleted of OGT via an si OGT- based approach. Lastly, expression of plasmids resistant to si OGT efficiently rescued the vimentin bridge phenotype, but the OGT-S20A rescue plasmids did not. Our results suggest a Chk1-OGT-vimentin pathway that regulates the intermediate filament network during cytokinesis. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Immunoexpression of intermediate filaments and morphological changes in the liver and bile duct of rats infected with Fasciola hepatica.

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Kolodziejczyk, L; Laszczyńska, M; Masiuk, M; Grabowska, M; Skrzydlewska, E

2015-01-01

We investigated the immunoexpression of the intermediate filament proteins, cytokeratin and desmin, and the morphological changes in the liver of rats during experimental fasciolosis at 4, 7 and 10 weeks post-infection. Rats were infected with 30 Fasciola hepatica metacercariae. Paraffin sections of the liver were stained using H & E, PAS and azan stains. Immunohistochemical reactions were performed using antibodies against cytokeratin and desmin. The experimental F. hepatica infection led to fibrosis and cirrhosis of the liver, and to inflammation of the common bile ducts. The expression of cytokeratin was increased in the epithelial cells of both the liver bile ductules at 4, 7 and 10 weeks post-infection and in the common bile ducts at 7 and 10 weeks post-infection compared to uninfected rats; expression in the common bile ducts was more intense. The myofibroblasts of the liver and smooth myocytes of the interlobular bile ducts and common bile ducts, showed a slight increase in desmin expression compared to the uninfected rats. The increased expression of cytokeratins in the hyperplastic rat common bile duct epithelium during the biliary phase of fasciolosis at 7 and 10 weeks post-infection may be explained by mechanical irritation by the parasite and an inflammatory reaction in the bile duct epithelium and in periductal fibrous tissue.

Methods for transforming and expression screening of filamentous fungal cells with a DNA library

Science.gov (United States)

Teter, Sarah; Lamsa, Michael; Cherry, Joel; Ward, Connie

2015-06-02

The present invention relates to methods for expression screening of filamentous fungal transformants, comprising: (a) isolating single colony transformants of a DNA library introduced into E. coli; (b) preparing DNA from each of the single colony E. coli transformants; (c) introducing a sample of each of the DNA preparations of step (b) into separate suspensions of protoplasts of a filamentous fungus to obtain transformants thereof, wherein each transformant contains one or more copies of an individual polynucleotide from the DNA library; (d) growing the individual filamentous fungal transformants of step (c) on selective growth medium, thereby permitting growth of the filamentous fungal transformants, while suppressing growth of untransformed filamentous fungi; and (e) measuring activity or a property of each polypeptide encoded by the individual polynucleotides. The present invention also relates to isolated polynucleotides encoding polypeptides of interest obtained by such methods, to nucleic acid constructs, expression vectors, and recombinant host cells comprising the isolated polynucleotides, and to methods of producing the polypeptides encoded by the isolated polynucleotides.

ngs (Notochord Granular Surface) Gene Encodes a Novel Type of Intermediate Filament Family Protein Essential for Notochord Maintenance in Zebrafish*

Science.gov (United States)

Tong, Xiangjun; Xia, Zhidan; Zu, Yao; Telfer, Helena; Hu, Jing; Yu, Jingyi; Liu, Huan; Zhang, Quan; Sodmergen; Lin, Shuo; Zhang, Bo

2013-01-01

The notochord is an important organ involved in embryonic patterning and locomotion. In zebrafish, the mature notochord consists of a single stack of fully differentiated, large vacuolated cells called chordocytes, surrounded by a single layer of less differentiated notochordal epithelial cells called chordoblasts. Through genetic analysis of zebrafish lines carrying pseudo-typed retroviral insertions, a mutant exhibiting a defective notochord with a granular appearance was isolated, and the corresponding gene was identified as ngs (notochord granular surface), which was specifically expressed in the notochord. In the mutants, the notochord started to degenerate from 32 hours post-fertilization, and the chordocytes were then gradually replaced by smaller cells derived from chordoblasts. The granular notochord phenotype was alleviated by anesthetizing the mutant embryos with tricaine to prevent muscle contraction and locomotion. Phylogenetic analysis showed that ngs encodes a new type of intermediate filament (IF) family protein, which we named chordostatin based on its function. Under the transmission electron microcopy, bundles of 10-nm-thick IF-like filaments were enriched in the chordocytes of wild-type zebrafish embryos, whereas the chordocytes in ngs mutants lacked IF-like structures. Furthermore, chordostatin-enhanced GFP (EGFP) fusion protein assembled into a filamentous network specifically in chordocytes. Taken together, our work demonstrates that ngs encodes a novel type of IF protein and functions to maintain notochord integrity for larval development and locomotion. Our work sheds light on the mechanisms of notochord structural maintenance, as well as the evolution and biological function of IF family proteins. PMID:23132861

ngs (notochord granular surface) gene encodes a novel type of intermediate filament family protein essential for notochord maintenance in zebrafish.

Science.gov (United States)

Tong, Xiangjun; Xia, Zhidan; Zu, Yao; Telfer, Helena; Hu, Jing; Yu, Jingyi; Liu, Huan; Zhang, Quan; Sodmergen; Lin, Shuo; Zhang, Bo

2013-01-25

The notochord is an important organ involved in embryonic patterning and locomotion. In zebrafish, the mature notochord consists of a single stack of fully differentiated, large vacuolated cells called chordocytes, surrounded by a single layer of less differentiated notochordal epithelial cells called chordoblasts. Through genetic analysis of zebrafish lines carrying pseudo-typed retroviral insertions, a mutant exhibiting a defective notochord with a granular appearance was isolated, and the corresponding gene was identified as ngs (notochord granular surface), which was specifically expressed in the notochord. In the mutants, the notochord started to degenerate from 32 hours post-fertilization, and the chordocytes were then gradually replaced by smaller cells derived from chordoblasts. The granular notochord phenotype was alleviated by anesthetizing the mutant embryos with tricaine to prevent muscle contraction and locomotion. Phylogenetic analysis showed that ngs encodes a new type of intermediate filament (IF) family protein, which we named chordostatin based on its function. Under the transmission electron microcopy, bundles of 10-nm-thick IF-like filaments were enriched in the chordocytes of wild-type zebrafish embryos, whereas the chordocytes in ngs mutants lacked IF-like structures. Furthermore, chordostatin-enhanced GFP (EGFP) fusion protein assembled into a filamentous network specifically in chordocytes. Taken together, our work demonstrates that ngs encodes a novel type of IF protein and functions to maintain notochord integrity for larval development and locomotion. Our work sheds light on the mechanisms of notochord structural maintenance, as well as the evolution and biological function of IF family proteins.

Phosphorylation and disassembly of intermediate filaments in mitotic cells

International Nuclear Information System (INIS)

Chou, Yinghao; Rosevear, E.; Goldman, R.D.

1989-01-01

As baby hamster kidney (BHK-21) cells enter mitosis, networks of intermediate filaments (IFs) are transformed into cytoplasmic aggregates of protofilaments. Coincident with this morphological change, the phosphate content of vimentin increases from 0.3 mol of P i per mol of protein in interphase to 1.9 mol of P i per mol of protein in mitosis. A similar increase in phosphate content is observed with desmin, from 0.5 mol of P i per mol of protein to 1.5 mol of P i per mol of protein. Fractionation of mitotic cell lysates by hydroxylapatite column chromatography reveals the presence of two IF protein kinase activities, designated as IF protein kinase I and IF protein kinase II. Comparison of two-dimensional 32 P-labeled phosphopeptide maps of vimentin and desmin phosphorylated in vivo in mitosis, and in vitro using partially purified kinase fractions, reveals extensive similarity in the two sets of phosphorylation sites. Phosphorylation of in vitro polymerized IFs by IF protein kinase II induces complete disassembly as determined by negative-stain electron microscopy. The results support the idea that the disassembly of IFs in mitosis is regulated by the phosphorylation of its subunit proteins

Functional characterisation of filamentous actin probe expression in neuronal cells.

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Shrujna Patel

Full Text Available Genetically encoded filamentous actin probes, Lifeact, Utrophin and F-tractin, are used as tools to label the actin cytoskeleton. Recent evidence in several different cell types indicates that these probes can cause changes in filamentous actin dynamics, altering cell morphology and function. Although these probes are commonly used to visualise actin dynamics in neurons, their effects on axonal and dendritic morphology has not been systematically characterised. In this study, we quantitatively analysed the effect of Lifeact, Utrophin and F-tractin on neuronal morphogenesis in primary hippocampal neurons. Our data show that the expression of actin-tracking probes significantly impacts on axonal and dendrite growth these neurons. Lifeact-GFP expression, under the control of a pBABE promoter, caused a significant decrease in total axon length, while another Lifeact-GFP expression, under the control of a CAG promoter, decreased the length and complexity of dendritic trees. Utr261-EGFP resulted in increased dendritic branching but Utr230-EGFP only accumulated in cell soma, without labelling any neurites. Lifeact-7-mEGFP and F-tractin-EGFP in a pEGFP-C1 vector, under the control of a CMV promoter, caused only minor changes in neuronal morphology as detected by Sholl analysis. The results of this study demonstrate the effects that filamentous actin tracking probes can have on the axonal and dendritic compartments of neuronal cells and emphasise the care that must be taken when interpreting data from experiments using these probes.

Calcium measurements in living filamentous fungi expressing codon-optimized aequorin

NARCIS (Netherlands)

Nelson, G.; Kozlova-Zwinderman, O.; Collis, A.J.; Knight, M.R.; Fincham, J.R.S.; Stanger, C.P.; Renwick, A.; Hessing, J.G.M.; Punt, P.J.; Hondel, C.A.M.J.J. van den; Read, N.D.

2004-01-01

Calcium signalling is little understood in filamentous fungi largely because easy and routine methods for calcium measurement in living hyphae have previously been unavailable. We have developed the recombinant aequorin method for this purpose. High levels of aequorin expression were obtained in

Regulation of protein phosphorylation of the intermediate-sized filament vimentin in the ciliary epithelium of the mammalian eye

International Nuclear Information System (INIS)

Coca-Prados, M.

1985-01-01

The intermediate-sized filaments of vimentin-type (Mr = 57,000) have been identified biochemically and immunochemically as a major cytoskeleton component in the ciliary epithelium of the mammalian eye. When human or rabbit ciliary processes, or cultured ciliary epithelial-derived cells were incubated in serum-free medium containing [ 32 P]orthophosphate and any of the following agents: 1) beta-adrenergic agonists (isoproterenol or epinephrine), 2) direct activators of adenylate cyclase (cholera toxin or forskolin), 3) analogs of cyclic AMP (8-Br-cAMP), or 4) prostaglandin E1, the phosphorylation of vimentin was significantly enhanced. The maximal enhancement ranged, in vivo and in vitro, from about 3-fold in human to 5-fold in rabbit, with either 1 mM 8-Br-cAMP or 0.1 microM forskolin. Indirect immunofluorescence microscopy using a monoclonal antibody, anti-vimentin, allowed the localization of vimentin filaments in cultured ciliary epithelial cells. Treatment of these cells in culture with the catecholamine hormone, isoproterenol (1 microM), resulted in a profound reorganization of vimentin filaments. This may be correlated with the enhanced levels of phosphorylated vimentin observed upon increasing cellular cyclic AMP

Spatial patterns of FUS-immunoreactive neuronal cytoplasmic inclusions (NCI) in neuronal intermediate filament inclusion disease (NIFID).

Science.gov (United States)

Armstrong, Richard A; Gearing, Marla; Bigio, Eileen H; Cruz-Sanchez, Felix F; Duyckaerts, Charles; Mackenzie, Ian R A; Perry, Robert H; Skullerud, Kari; Yokoo, Hideaki; Cairns, Nigel J

2011-11-01

Neuronal intermediate filament inclusion disease (NIFID), a rare form of frontotemporal lobar degeneration (FTLD), is characterized neuropathologically by focal atrophy of the frontal and temporal lobes, neuronal loss, gliosis, and neuronal cytoplasmic inclusions (NCI) containing epitopes of ubiquitin and neuronal intermediate filament (IF) proteins. Recently, the 'fused in sarcoma' (FUS) protein (encoded by the FUS gene) has been shown to be a component of the inclusions of NIFID. To further characterize FUS proteinopathy in NIFID, we studied the spatial patterns of the FUS-immunoreactive NCI in frontal and temporal cortex of 10 cases. In the cerebral cortex, sectors CA1/2 of the hippocampus, and the dentate gyrus (DG), the FUS-immunoreactive NCI were frequently clustered and the clusters were regularly distributed parallel to the tissue boundary. In a proportion of cortical gyri, cluster size of the NCI approximated to those of the columns of cells was associated with the cortico-cortical projections. There were no significant differences in the frequency of different types of spatial patterns with disease duration or disease stage. Clusters of NCI in the upper and lower cortex were significantly larger using FUS compared with phosphorylated, neurofilament heavy polypeptide (NEFH) or α-internexin (INA) immunohistochemistry (IHC). We concluded: (1) FUS-immunoreactive NCI exhibit similar spatial patterns to analogous inclusions in the tauopathies and synucleinopathies, (2) clusters of FUS-immunoreactive NCI are larger than those revealed by NEFH or ΙΝΑ, and (3) the spatial patterns of the FUS-immunoreactive NCI suggest the degeneration of the cortico-cortical projections in NIFID.

Binding of integrin alpha6beta4 to plectin prevents plectin association with F-actin but does not interfere with intermediate filament binding

NARCIS (Netherlands)

Geerts, D.; Fontao, L.; Nievers, M. G.; Schaapveld, R. Q.; Purkis, P. E.; Wheeler, G. N.; Lane, E. B.; Leigh, I. M.; Sonnenberg, A.

1999-01-01

Hemidesmosomes are stable adhesion complexes in basal epithelial cells that provide a link between the intermediate filament network and the extracellular matrix. We have investigated the recruitment of plectin into hemidesmosomes by the alpha6beta4 integrin and have shown that the cytoplasmic

Molecular transformation, gene cloning, and gene expression systems for filamentous fungi

Science.gov (United States)

Gold, Scott E.; Duick, John W.; Redman, Regina S.; Rodriguez, Rusty J.

2001-01-01

This chapter discusses the molecular transformation, gene cloning, and gene expression systems for filamentous fungi. Molecular transformation involves the movement of discrete amounts of DNA into cells, the expression of genes on the transported DNA, and the sustainable replication of the transforming DNA. The ability to transform fungi is dependent on the stable replication and expression of genes located on the transforming DNA. Three phenomena observed in bacteria, that is, competence, plasmids, and restriction enzymes to facilitate cloning, were responsible for the development of molecular transformation in fungi. Initial transformation success with filamentous fungi, involving the complementation of auxotrophic mutants by exposure to sheared genomic DNA or RNA from wt isolates, occurred with low transformation efficiencies. In addition, it was difficult to retrieve complementing DNA fragments and isolate genes of interest. This prompted the development of transformation vectors and methods to increase efficiencies. The physiological studies performed with fungi indicated that the cell wall could be removed to generate protoplasts. It was evident that protoplasts could be transformed with significantly greater efficiencies than walled cells.

The intermediate filament network protein, vimentin, is required for parvoviral infection

Energy Technology Data Exchange (ETDEWEB)

Fay, Nikta; Panté, Nelly, E-mail: pante@zoology.ubc.ca

2013-09-15

Intermediate filaments (IFs) have recently been shown to serve novel roles during infection by many viruses. Here we have begun to study the role of IFs during the early steps of infection by the parvovirus minute virus of mice (MVM). We found that during early infection with MVM, after endosomal escape, the vimentin IF network was considerably altered, yielding collapsed immunofluorescence staining near the nuclear periphery. Furthermore, we found that vimentin plays an important role in the life cycle of MVM. The number of cells, which successfully replicated MVM, was reduced in infected cells in which the vimentin network was genetically or pharmacologically modified; viral endocytosis, however, remained unaltered. Perinuclear accumulation of MVM-containing vesicles was reduced in cells lacking vimentin. Our data suggests that vimentin is required for the MVM life cycle, presenting possibly a dual role: (1) following MVM escape from endosomes and (2) during endosomal trafficking of MVM. - Highlights: • MVM infection changes the distribution of the vimentin network to perinuclear regions. • Disrupting the vimentin network with acrylamide decreases MVM replication. • MVM replication is significantly reduced in vimentin-null cells. • Distribution of MVM-containing vesicles is affected in MVM infected vimentin-null cells.

The intermediate filament network protein, vimentin, is required for parvoviral infection

International Nuclear Information System (INIS)

Fay, Nikta; Panté, Nelly

2013-01-01

Intermediate filaments (IFs) have recently been shown to serve novel roles during infection by many viruses. Here we have begun to study the role of IFs during the early steps of infection by the parvovirus minute virus of mice (MVM). We found that during early infection with MVM, after endosomal escape, the vimentin IF network was considerably altered, yielding collapsed immunofluorescence staining near the nuclear periphery. Furthermore, we found that vimentin plays an important role in the life cycle of MVM. The number of cells, which successfully replicated MVM, was reduced in infected cells in which the vimentin network was genetically or pharmacologically modified; viral endocytosis, however, remained unaltered. Perinuclear accumulation of MVM-containing vesicles was reduced in cells lacking vimentin. Our data suggests that vimentin is required for the MVM life cycle, presenting possibly a dual role: (1) following MVM escape from endosomes and (2) during endosomal trafficking of MVM. - Highlights: • MVM infection changes the distribution of the vimentin network to perinuclear regions. • Disrupting the vimentin network with acrylamide decreases MVM replication. • MVM replication is significantly reduced in vimentin-null cells. • Distribution of MVM-containing vesicles is affected in MVM infected vimentin-null cells

Interactions between the intermediate filaments of vimentin and natural or artificial lipid membranes

International Nuclear Information System (INIS)

Perides, G.

1986-01-01

The study has provided evidence to prove that intermediate filaments (IF) are not only encountered in the vicinity of several cellular membrane systems but even become attached to those membranes by stable mechanical bonds. Studies using photoaffinity markers permitted to show in vivo that vimentin occurs in the immediate neighbourhood of membrane lipids. Titration of cellular membranes with radioactively labelled vimentin and desmin pointed to the fact that there is a large excess of acceptor molecules for IF proteins, from which it was concluded that vimentin directly binds to the lipids. This is also consistent with the finding that vesicles made up of cellular lipids readily bind to vimentin filaments and may even interfere with the formation of the latter. The highest vimentin affinity was observed for negatively charged phospholipids, which led to the theory that the association of IF and cellular membranes is firstly attributable to an interaction between the positive N-terminals of IF proteins and upper polar groups of negative phospholipids. The binding of vimentin to cellular mebranes changes under the influence of cellular growth processes and extracellular factors. This was also suggested by the reduced amounts of membrane-bound vimentin found after the incubation of cells in a serum-free medium and the prompt increases in the vimentin content of those membranes, after serum was added. This is one example, among several others, to show that the reactions between IF and cellular membranes are of a reversible nature and controlled and shaped by the cell itself. (orig./MG) [de

Intermediate filament immunohistochemistry of astroglial cells in the leopard gecko, Eublepharis macularius.

Science.gov (United States)

Lazzari, Maurizio; Franceschini, Valeria

2005-11-01

The distribution of intermediate filament molecular markers, glial fibrillary acidic protein (GFAP) and vimentin, has been studied in the central nervous system (CNS) of the adult leopard gecko, Eublepharis macularius. This immunohistochemical study points out the presence of different astroglial cell types. The main pattern is constituted by ependymal radial glia, which have their cell bodies located in the ependymal layer throughout the brain ventricular system. Radial glia proper or radial astrocytes show their cell bodies displaced from the ependymal layer into a periependymal zone and are observed only in the spinal cord. Star-shaped astrocytes are scarce. They are detected in the ventral and lateral regions of the diencephalon and mesencephalon, in the superficial layer of the optic tectum, in the ventral medulla oblongata, and in the ventral and lateral spinal cord. In the different regions of the CNS, the staining intensity appears not to be identical even in the same cellular type. The results reported in the present study show an heterogeneous feature of the astroglial pattern in E. macularius.

Fine filament NbTi superconductive composite

International Nuclear Information System (INIS)

Hong, S.; Grabinsky, G.; Marancik, W.; Pattanayak, D.

1986-01-01

The large superconducting magnet for the high energy physics accelerator requires fine filament composite to minimize the field error due to the persistent current in the filaments. New concepts toward the fine filament composite and its cable fabrication are discussed. Two-stage cables of fine wire with intermediate number of filaments were introduced. The first stage was six wires cables around one and in the second stage this was used to produce a Rutherford cable. The advantage of this process is in the ease of billet fabrication since the number of filaments in a single wire is within the range of easy billet fabrication. The disadvantage is in the cable fabrication. One of the major concerns in the fabrication of fine NbTi filaments composite in a copper matrix is the intermetallic compound formation during the extrusion and heat treatment steps. The hard intermetallic particles degrade the uniformity of the filaments and reduce the critical current density. The process of using Nb barrier between the filaments and copper matrix in order to prevent this CuTi intermetallic particle formation is described

Foveolar Müller Cells of the Pied Flycatcher: Morphology and Distribution of Intermediate Filaments Regarding Cell Transparency.

Science.gov (United States)

Zueva, Lidia; Golubeva, Tatiana; Korneeva, Elena; Makarov, Vladimir; Khmelinskii, Igor; Inyushin, Mikhail

2016-04-01

Specialized intermediate filaments (IFs) have critical importance for the clearness and uncommon transparency of vertebrate lens fiber cells, although the physical mechanisms involved are poorly understood. Recently, an unusual low-scattering light transport was also described in retinal Müller cells. Exploring the function of IFs in Müller cells, we have studied the morphology and distribution pattern of IFs and other cytoskeletal filaments inside the Müller cell main processes in the foveolar part of the avian (pied flycatcher) retina. We found that some IFs surrounded by globular nanoparticles (that we suggest are crystallines) are present in almost every part of the Müller cells that span the retina, including the microvilli. Unlike IFs implicated in the mechanical architecture of the cell, these IFs are not connected to any specific cellular membranes. Instead, they are organized into bundles, passing inside the cell from the endfeet to the photoreceptor, following the geometry of the processes, and repeatedly circumventing numerous obstacles. We believe that the presently reported data effectively confirm that the model of nanooptical channels built of the IFs may provide a viable explanation of Müller cell transparency.

Co-expression of cytokeratins and vimentin by highly invasive trophoblast in the white-winged vampire bat, Diaemus youngi, and the black mastiff bat, Molossus ater, with observations on intermediate filament proteins in the decidua and intraplacental trophoblast.

Science.gov (United States)

Badwaik, N K; Rasweiler, J J; Muradali, F

1998-11-01

Histological and immunocytochemical studies of gravid reproductive tracts obtained from the white-winged vampire bat (Diaemus youngi) and the black mastiff bat (Molossus ater) have established that both species develop unusually invasive trophoblast. This is released by the developing discoidal haemochorial placenta, expresses both cytokeratins and vimentin, and invades the myometrium and adjacent tissues (including the ovaries) via interstitial migration within the walls of maternal blood vessels. Hence, this trophoblast is noteworthy for the extent to which it undergoes an epithelial-mesenchymal transformation. In Molossus, it originates from the cytotrophoblastic shell running along the base of the placenta, is mononuclear, and preferentially invades maternal arterial vessels serving the discoidal placenta. This trophoblast may have a role in dilatation of these vessels when the discoidal placenta becomes functional. In Diaemus, the highly invasive trophoblast appears to originate instead from a layer of syncytiotrophoblast on the periphery of the placenta is multinucleated, and vigorously invades both arterial and venous vessels. During late pregnancy, it becomes extensively branched and sends attenuated processes around many of the myometrial smooth muscle fibres. In view of its distribution, this trophoblast could have important influences upon myometrial contractility and the function of blood vessels serving the gravid tract. Other aspects of intermediate filament expression in the uteri and placentae of these bats are also noteworthy. Many of the decidual giant cells in Molossus co-express cytokeratins and vimentin, while the syncytiotrophoblast lining the placental labyrinth in Diaemus late in pregnancy expresses little cytokeratin.

Dynamic gradients of an intermediate filament-like cytoskeleton are recruited by a polarity landmark during apical growth.

Science.gov (United States)

Fuchino, Katsuya; Bagchi, Sonchita; Cantlay, Stuart; Sandblad, Linda; Wu, Di; Bergman, Jessica; Kamali-Moghaddam, Masood; Flärdh, Klas; Ausmees, Nora

2013-05-21

Intermediate filament (IF)-like cytoskeleton emerges as a versatile tool for cellular organization in all kingdoms of life, underscoring the importance of mechanistically understanding its diverse manifestations. We showed previously that, in Streptomyces (a bacterium with a mycelial lifestyle similar to that of filamentous fungi, including extreme cell and growth polarity), the IF protein FilP confers rigidity to the hyphae by an unknown mechanism. Here, we provide a possible explanation for the IF-like function of FilP by demonstrating its ability to self-assemble into a cis-interconnected regular network in vitro and its localization into structures consistent with a cytoskeletal network in vivo. Furthermore, we reveal that a spatially restricted interaction between FilP and DivIVA, the main component of the Streptomyces polarisome complex, leads to formation of apical gradients of FilP in hyphae undergoing active tip extension. We propose that the coupling between the mechanism driving polar growth and the assembly of an IF cytoskeleton provides each new hypha with an additional stress-bearing structure at its tip, where the nascent cell wall is inevitably more flexible and compliant while it is being assembled and matured. Our data suggest that recruitment of cytoskeleton around a cell polarity landmark is a broadly conserved strategy in tip-growing cells.

Nestin expression in the cell lines derived from glioblastoma multiforme

International Nuclear Information System (INIS)

Veselska, Renata; Kuglik, Petr; Cejpek, Pavel; Svachova, Hana; Neradil, Jakub; Loja, Tomas; Relichova, Jirina

2006-01-01

Nestin is a protein belonging to class VI of intermediate filaments that is produced in stem/progenitor cells in the mammalian CNS during development and is consecutively replaced by other intermediate filament proteins (neurofilaments, GFAP). Down-regulated nestin may be re-expressed in the adult organism under certain pathological conditions (brain injury, ischemia, inflammation, neoplastic transformation). Our work focused on a detailed study of the nestin cytoskeleton in cell lines derived from glioblastoma multiforme, because re-expression of nestin together with down-regulation of GFAP has been previously reported in this type of brain tumor. Two cell lines were derived from the tumor tissue of patients treated for glioblastoma multiforme. Nestin and other cytoskeletal proteins were visualized using imunocytochemical methods: indirect immunofluorescence and immunogold-labelling. Using epifluorescence and confocal microscopy, we described the morphology of nestin-positive intermediate filaments in glioblastoma cells of both primary cultures and the derived cell lines, as well as the reorganization of nestin during mitosis. Our most important result came through transmission electron microscopy and provided clear evidence that nestin is present in the cell nucleus. Detailed information concerning the pattern of the nestin cytoskeleton in glioblastoma cell lines and especially the demonstration of nestin in the nucleus represent an important background for further studies of nestin re-expression in relationship to tumor malignancy and invasive potential

CNS-syndrome. Characterization of rat brain intermediate filaments

International Nuclear Information System (INIS)

Nedzvetskij, V.S.; Busygina, S.G.; Berezin, V.A.; Dvoretskij, A.I.

1990-01-01

A study was made of the effect of ionizing radiation on the content and polypeptide composition of filamentous and soluble glial fibrillary acidic protein (GFAP) in different regions of rat brain. Ionizing radiation was shown to decrease considerably the level of soluble GFAP in cerebral cortex, cerebellum, middle brain and hippocampus. Polypeptide composition of soluble GFAP detected by the immonublot-method was found to be changed considerably in different brain areas of irradiated animals

International express student's book : pre-intermediate

CERN Document Server

Taylor, Liz

1996-01-01

The New Edition of International Express Pre-Intermediate retains all the keys features of this popular and successel four-level course. It combines engaging, up-to-date topics with a time-efficient and student-centred approach to language work, and clearly focused activities that reflect learner's real communicative needs - the ideal course for professional adults who use English for work, travel, and socializing.

Cellular responses to the expression of unstable secretory proteins in the filamentous fungus Aspergillus oryzae.

Science.gov (United States)

Yokota, Jun-Ichi; Shiro, Daisuke; Tanaka, Mizuki; Onozaki, Yasumichi; Mizutani, Osamu; Kakizono, Dararat; Ichinose, Sakurako; Shintani, Tomoko; Gomi, Katsuya; Shintani, Takahiro

2017-03-01

Filamentous fungi are often used as cell factories for recombinant protein production because of their ability to secrete large quantities of hydrolytic enzymes. However, even using strong transcriptional promoters, yields of nonfungal proteins are generally much lower than those of fungal proteins. Recent analyses revealed that expression of certain nonfungal secretory proteins induced the unfolded protein response (UPR), suggesting that they are recognized as proteins with folding defects in filamentous fungi. More recently, however, even highly expressed endogenous secretory proteins were found to evoke the UPR. These findings raise the question of whether the unfolded or misfolded state of proteins is selectively recognized by quality control mechanisms in filamentous fungi. In this study, a fungal secretory protein (1,2-α-D-mannosidase; MsdS) with a mutation that decreases its thermostability was expressed at different levels in Aspergillus oryzae. We found that, at moderate expression levels, wild-type MsdS was secreted to the medium, while the mutant was not. In the strain with a deletion for the hrdA gene, which is involved in the endoplasmic reticulum-associated degradation pathway, mutant MsdS had specifically increased levels in the intracellular fraction but was not secreted. When overexpressed, the mutant protein was secreted to the medium to a similar extent as the wild-type protein; however, the mutant underwent hyperglycosylation and induced the UPR. Deletion of α-amylase (the most abundant secretory protein in A. oryzae) alleviated the UPR induction by mutant MsdS overexpression. These findings suggest that misfolded MsdS and unfolded species of α-amylase might act synergistically for UPR induction.

The dermatan sulfate proteoglycan decorin modulates α2β1 integrin and the vimentin intermediate filament system during collagen synthesis.

Directory of Open Access Journals (Sweden)

Oliver Jungmann

Full Text Available Decorin, a small leucine-rich proteoglycan harboring a dermatan sulfate chain at its N-terminus, is involved in regulating matrix organization and cell signaling. Loss of the dermatan sulfate of decorin leads to an Ehlers-Danlos syndrome characterized by delayed wound healing. Decorin-null (Dcn(-/- mice display a phenotype similar to that of EDS patients. The fibrillar collagen phenotype of Dcn(-/- mice could be rescued in vitro by decorin but not with decorin lacking the glycosaminoglycan chain. We utilized a 3D cell culture model to investigate the impact of the altered extracellular matrix on Dcn(-/- fibroblasts. Using 2D gel electrophoresis followed by mass spectrometry, we identified vimentin as one of the proteins that was differentially upregulated by the presence of decorin. We discovered that a decorin-deficient matrix leads to abnormal nuclear morphology in the Dcn(-/- fibroblasts. This phenotype could be rescued by the decorin proteoglycan but less efficiently by the decorin protein core. Decorin treatment led to a significant reduction of the α2β1 integrin at day 6 in Dcn(-/- fibroblasts, whereas the protein core had no effect on β1. Interestingly, only the decorin core induced mRNA synthesis, phosphorylation and de novo synthesis of vimentin indicating that the proteoglycan decorin in the extracellular matrix stabilizes the vimentin intermediate filament system. We could support these results in vivo, because the dermis of wild-type mice have more vimentin and less β1 integrin compared to Dcn(-/-. Furthermore, the α2β1 null fibroblasts also showed a reduced amount of vimentin compared to wild-type. These data show for the first time that decorin has an impact on the biology of α2β1 integrin and the vimentin intermediate filament system. Moreover, our findings provide a mechanistic explanation for the reported defects in wound healing associated with the Dcn(-/- phenotype.

Delayed Failure of Hi-Nicalon and Hi-Nicalon S Multi-filament Tows and Single Filaments at Intermediate Temperatures (500 degrees-800 degrees C)

International Nuclear Information System (INIS)

Gauthier, W.; Lamon, J.

2009-01-01

Previous results have shown that tows of SiC Nicalon fibers are sensitive to the phenomenon of delayed failure, at temperatures below 700 C. The present paper examines the static fatigue of Hi-Nicalon and Hi-Nicalon S when subjected to constant load, at temperatures between 500 and 800 C in air. Multi-filament tows and single filaments were tested. Experimental data show that the rupture times of tows depend on the applied stress according to the conventional power law tσ n =A. In contrast, the stress-rupture time data obtained on single filaments exhibit significant scatter. A model based on slow crack growth in single filaments shows that the stress-rupture of fiber tows follows the conventional time power law. The dependence on temperature was introduced. The model allowed sound calculations of tow lifetimes and characteristics of the slow crack growth phenomenon to be extracted from the tow stress-rupture time data. (authors)

The spectrum and severity of FUS-immunoreactive inclusions in the frontal and temporal lobes of ten cases of neuronal intermediate filament inclusion disease.

Science.gov (United States)

Armstrong, Richard A; Gearing, Marla; Bigio, Eileen H; Cruz-Sanchez, Felix F; Duyckaerts, Charles; Mackenzie, Ian R A; Perry, Robert H; Skullerud, Kari; Yokoo, Hedeaki; Cairns, Nigel J

2011-02-01

Neuronal intermediate filament inclusion disease (NIFID), a rare form of frontotemporal lobar degeneration (FTLD), is characterized neuropathologically by focal atrophy of the frontal and temporal lobes, neuronal loss, gliosis, and neuronal cytoplasmic inclusions (NCI) containing epitopes of ubiquitin and neuronal intermediate filament proteins. Recently, the 'fused in sarcoma' (FUS) protein (encoded by the FUS gene) has been shown to be a component of the inclusions of familial amyotrophic lateral sclerosis with FUS mutation, NIFID, basophilic inclusion body disease, and atypical FTLD with ubiquitin-immunoreactive inclusions (aFTLD-U). To further characterize FUS proteinopathy in NIFID, and to determine whether the pathology revealed by FUS immunohistochemistry (IHC) is more extensive than α-internexin, we have undertaken a quantitative assessment of ten clinically and neuropathologically well-characterized cases using FUS IHC. The densities of NCI were greatest in the dentate gyrus (DG) and in sectors CA1/2 of the hippocampus. Anti-FUS antibodies also labeled glial inclusions (GI), neuronal intranuclear inclusions (NII), and dystrophic neurites (DN). Vacuolation was extensive across upper and lower cortical layers. Significantly greater densities of abnormally enlarged neurons and glial cell nuclei were present in the lower compared with the upper cortical laminae. FUS IHC revealed significantly greater numbers of NCI in all brain regions especially the DG. Our data suggest: (1) significant densities of FUS-immunoreactive NCI in NIFID especially in the DG and CA1/2; (2) infrequent FUS-immunoreactive GI, NII, and DN; (3) widely distributed vacuolation across the cortex, and (4) significantly more NCI revealed by FUS than α-internexin IHC.

Demonstration of mechanical connections between integrins, cytoskeletal filaments, and nucleoplasm that stabilize nuclear structure

Science.gov (United States)

Maniotis, A. J.; Chen, C. S.; Ingber, D. E.

1997-01-01

We report here that living cells and nuclei are hard-wired such that a mechanical tug on cell surface receptors can immediately change the organization of molecular assemblies in the cytoplasm and nucleus. When integrins were pulled by micromanipulating bound microbeads or micropipettes, cytoskeletal filaments reoriented, nuclei distorted, and nucleoli redistributed along the axis of the applied tension field. These effects were specific for integrins, independent of cortical membrane distortion, and were mediated by direct linkages between the cytoskeleton and nucleus. Actin microfilaments mediated force transfer to the nucleus at low strain; however, tearing of the actin gel resulted with greater distortion. In contrast, intermediate filaments effectively mediated force transfer to the nucleus under both conditions. These filament systems also acted as molecular guy wires to mechanically stiffen the nucleus and anchor it in place, whereas microtubules acted to hold open the intermediate filament lattice and to stabilize the nucleus against lateral compression. Molecular connections between integrins, cytoskeletal filaments, and nuclear scaffolds may therefore provide a discrete path for mechanical signal transfer through cells as well as a mechanism for producing integrated changes in cell and nuclear structure in response to changes in extracellular matrix adhesivity or mechanics.

International express student's book : intermediate : with pocket book

CERN Document Server

Harding, Keith

2005-01-01

The New Edition of International Express Intermediate retains all the key features of this popular and successful four-level course. It combines engaging, up-to-date topics with a time-efficient and student-centred approach to language work, and clearly focused activities that reflect learners' real communicative needs - the ideal course for professional adults who use English for work, travel, and socializing.

EST Table: FS927325 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available ar to Restin (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Strongylocentrotus pu...rpuratus] ref|XP_001183478.1| PREDICTED: similar to Restin (Reed-Steinberg cell-expressed intermediate filam...CTED: similar to restin (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Tribolium castaneum] CK533543 fwgP ...

Differential gene expression and filamentation of Listeria monocytogenes 08-5923 exposed to sodium lactate and sodium diacetate.

Science.gov (United States)

Liu, Xiaoji; Basu, Urmila; Miller, Petr; McMullen, Lynn M

2017-05-01

This study reports the gene expression and filamentation in Listeria monocytogenes 08-5923 following exposure to food preservatives sodium lactate (NaL) and sodium diacetate (SD). L. monocytogenes 08-5923 was challenged with a mixture of NaL/SD, NaL or sodium acetate at 37 °C in tryptic soy broth. In the initial study, L. monocytogenes 08-5923 was exposed to NaL/SD for 24 h. The transcriptome was investigated by RNA sequencing. A stress response network was discovered in L. monocytogenes 08-5923, which is mediated by genes encoding two-component systems (hisJ, lisK, OmpR family gene, resE) and RNA polymerase factors (sigC, sigH). NaL/SD resulted in the down-regulation of genes in glycolysis (pykA, eno, fbaA, pgm) and up-regulation of genes in DNA repair (radC), cell division (ftsE) and cell structure synthesis (flagella synthesis: flgK, fliF, fliD). Filamentation was monitored by flow cytometry. NaL/SD mixture resulted in filamentation in L. monocytogenes 08-5923. Longer exposure was required to induce filamentation in L. monocytogenes for SD (24 h) than for NaL (8 h) when cells were exposed to individual salt. The quantitative real time PCR analysis revealed the down-regulation of ftsE in filamented cells of Listeria exposed to NaL or sodium acetate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Planck intermediate results XXXIII. Signature of the magnetic field geometry of interstellar filaments in dust polarization maps

DEFF Research Database (Denmark)

Ade, P. A. R.; Aghanim, N.; Alves, M. I. R.

2016-01-01

of the filaments and therefore to provide insight into the structure of their magnetic field (B). We present the polarization maps of three nearby (several parsecs long) star-forming filaments of moderate column density (N-H about 1022 cm-2): Musca, B211, and L1506. These three filaments are detected above...... angles in the three filaments (ψfil) are coherent along their lengths and not the same as in their backgrounds (ψbg). The differences between ψfil and ψbg are 12 degrees and 54 degrees for Musca and L1506, respectively, and only 6 degrees in the case of B211. These differences for Musca and L1506...... (by, e. g., radiative torques) and the structure of the B-field in causing variations in p, but we argue that the decrease in p from the backgrounds to the filaments results in part from depolarization associated with the 3D structure of the B-field: both its orientation in the POS and with respect...

Simulating the formation of keratin filament networks by a piecewise-deterministic Markov process.

Science.gov (United States)

Beil, Michael; Lück, Sebastian; Fleischer, Frank; Portet, Stéphanie; Arendt, Wolfgang; Schmidt, Volker

2009-02-21

Keratin intermediate filament networks are part of the cytoskeleton in epithelial cells. They were found to regulate viscoelastic properties and motility of cancer cells. Due to unique biochemical properties of keratin polymers, the knowledge of the mechanisms controlling keratin network formation is incomplete. A combination of deterministic and stochastic modeling techniques can be a valuable source of information since they can describe known mechanisms of network evolution while reflecting the uncertainty with respect to a variety of molecular events. We applied the concept of piecewise-deterministic Markov processes to the modeling of keratin network formation with high spatiotemporal resolution. The deterministic component describes the diffusion-driven evolution of a pool of soluble keratin filament precursors fueling various network formation processes. Instants of network formation events are determined by a stochastic point process on the time axis. A probability distribution controlled by model parameters exercises control over the frequency of different mechanisms of network formation to be triggered. Locations of the network formation events are assigned dependent on the spatial distribution of the soluble pool of filament precursors. Based on this modeling approach, simulation studies revealed that the architecture of keratin networks mostly depends on the balance between filament elongation and branching processes. The spatial distribution of network mesh size, which strongly influences the mechanical characteristics of filament networks, is modulated by lateral annealing processes. This mechanism which is a specific feature of intermediate filament networks appears to be a major and fast regulator of cell mechanics.

Differential filamentation of Candida albicans and Candida dubliniensis Is governed by nutrient regulation of UME6 expression.

LENUS (Irish Health Repository)

O'Connor, Leanne

2010-09-01

Candida dubliniensis is closely related to Candida albicans; however, it is responsible for fewer infections in humans and is less virulent in animal models of infection. C. dubliniensis forms fewer hyphae in vivo, and this may contribute to its reduced virulence. In this study we show that, unlike C. albicans, C. dubliniensis fails to form hyphae in yeast extract-peptone-dextrose (YPD) medium supplemented with 10% (vol\\/vol) fetal calf serum (YPDS medium). However, C. dubliniensis filaments in water plus 10% (vol\\/vol) fetal calf serum (WS), and this filamentation is inhibited by the addition of peptone and glucose. Repression of filamentation in YPDS medium could be partly overcome by preculture in synthetic Lee\\'s medium. Unlike C. albicans, inoculation of C. dubliniensis in YPDS medium did not result in increased UME6 transcription. However, >100-fold induction of UME6 was observed when C. dubliniensis was inoculated in nutrient-poor WS medium. The addition of increasing concentrations of peptone to WS medium had a dose-dependent effect on reducing UME6 expression. Transcript profiling of C. dubliniensis hyphae in WS medium identified a starvation response involving expression of genes in the glyoxylate cycle and fatty acid oxidation. In addition, a core, shared transcriptional response with C. albicans could be identified, including expression of virulence-associated genes including SAP456, SAP7, HWP1, and SOD5. Preculture in nutrient-limiting medium enhanced adherence of C. dubliniensis, epithelial invasion, and survival following coculture with murine macrophages. In conclusion, C. albicans, unlike C. dubliniensis, appears to form hyphae in liquid medium regardless of nutrient availability, which may account for its increased capacity to cause disease in humans.

The Serine/threonine kinase Stk33 exhibits autophosphorylation and phosphorylates the intermediate filament protein Vimentin

Directory of Open Access Journals (Sweden)

Herrmann Harald

2008-09-01

Full Text Available Abstract Background Colocalization of Stk33 with vimentin by double immunofluorescence in certain cells indicated that vimentin might be a target for phosphorylation by the novel kinase Stk33. We therefore tested in vitro the ability of Stk33 to phosphorylate recombinant full length vimentin and amino-terminal truncated versions thereof. In order to prove that Stk33 and vimentin are also in vivo associated proteins co-immunoprecipitation experiments were carried out. For testing the enzymatic activity of immunoprecipitated Stk33 we incubated precipitated Stk33 with recombinant vimentin proteins. To investigate whether Stk33 binds directly to vimentin, an in vitro co-sedimentation assay was performed. Results The results of the kinase assays demonstrate that Stk33 is able to specifically phosphorylate the non-α-helical amino-terminal domain of vimentin in vitro. Furthermore, co-immunoprecipitation experiments employing cultured cell extracts indicate that Stk33 and vimentin are associated in vivo. Immunoprecipitated Stk33 has enzymatic activity as shown by successful phosphorylation of recombinant vimentin proteins. The results of the co-sedimentation assay suggest that vimentin binds directly to Stk33 and that no additional protein mediates the association. Conclusion We hypothesize that Stk33 is involved in the in vivo dynamics of the intermediate filament cytoskeleton by phosphorylating vimentin.

EST Table: FS851943 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available ar to restin (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Tribolium castaneum] ...o restin (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Tribolium castaneum] FS906662 fner ...

DISCOVERY OF C IV EMISSION FILAMENTS IN M87

International Nuclear Information System (INIS)

Sparks, W. B.; Pringle, J. E.; Cracraft, M.; Donahue, M.; Voit, M.; Carswell, R.; Martin, R. G.

2009-01-01

Gas at intermediate temperatures between the hot X-ray-emitting coronal gas in galaxies at the centers of galaxy clusters and the much cooler optical line emitting filaments yields information on transport processes and plausible scenarios for the relationship between X-ray cool cores and other galactic phenomena such as mergers or the onset of an active galactic nucleus. Hitherto, detection of intermediate temperature gas has proven elusive. Here, we present FUV imaging of the 'low excitation' emission filaments of M87 and show strong evidence for the presence of C IV 1549 A emission which arises in gas at temperature ∼10 5 K co-located with Hα+[N II] emission from cooler ∼10 4 K gas. We infer that the hot and cool phases are in thermal communication, and show that quantitatively the emission strength is consistent with thermal conduction, which in turn may account for many of the observed characteristics of cool-core galaxy clusters.

EST Table: FS921686 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available ar to restin (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Tribolium castaneum] ...o restin (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Tribolium castaneum] FS906662 fwgP ...

EST Table: BY928817 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available DICTED: similar to restin (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Triboliu...ED: similar to restin (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Tribolium castaneum] BY928817 fcP8 ...

Role of Tellurite Resistance Operon in Filamentous Growth of Yersinia pestis in Macrophages.

Science.gov (United States)

Ponnusamy, Duraisamy; Clinkenbeard, Kenneth D

2015-01-01

Yersinia pestis initiates infection by parasitism of host macrophages. In response to macrophage infections, intracellular Y. pestis can assume a filamentous cellular morphology which may mediate resistance to host cell innate immune responses. We previously observed the expression of Y. pestis tellurite resistance proteins TerD and TerE from the terZABCDE operon during macrophage infections. Others have observed a filamentous response associated with expression of tellurite resistance operon in Escherichia coli exposed to tellurite. Therefore, in this study we examine the potential role of Y. pestis tellurite resistance operon in filamentous cellular morphology during macrophage infections. In vitro treatment of Y. pestis culture with sodium tellurite (Na2TeO3) caused the bacterial cells to assume a filamentous phenotype similar to the filamentous phenotype observed during macrophage infections. A deletion mutant for genes terZAB abolished the filamentous morphologic response to tellurite exposure or intracellular parasitism, but without affecting tellurite resistance. However, a terZABCDE deletion mutant abolished both filamentous morphologic response and tellurite resistance. Complementation of the terZABCDE deletion mutant with terCDE, but not terZAB, partially restored tellurite resistance. When the terZABCDE deletion mutant was complemented with terZAB or terCDE, Y. pestis exhibited filamentous morphology during macrophage infections as well as while these complemented genes were being expressed under an in vitro condition. Further in E. coli, expression of Y. pestis terZAB, but not terCDE, conferred a filamentous phenotype. These findings support the role of Y. pestis terZAB mediation of the filamentous response phenotype; whereas, terCDE confers tellurite resistance. Although the beneficial role of filamentous morphological responses by Y. pestis during macrophage infections is yet to be fully defined, it may be a bacterial adaptive strategy to macrophage

CF2 represses Actin 88F gene expression and maintains filament balance during indirect flight muscle development in Drosophila.

Directory of Open Access Journals (Sweden)

Kathleen M Gajewski

2010-05-01

Full Text Available The zinc finger protein CF2 is a characterized activator of muscle structural genes in the body wall muscles of the Drosophila larva. To investigate the function of CF2 in the indirect flight muscle (IFM, we examined the phenotypes of flies bearing five homozygous viable mutations. The gross structure of the IFM was not affected, but the stronger hypomorphic alleles caused an increase of up to 1.5X in the diameter of the myofibrils. This size increase did not cause any disruption of the hexameric arrangement of thick and thin filaments. RT-PCR analysis revealed an increase in the transcription of several structural genes. Ectopic overexpression of CF2 in the developing IFM disrupts muscle formation. While our results indicate a role for CF2 as a direct negative regulator of the thin filament protein gene Actin 88F (Act88F, effects on levels of transcripts of myosin heavy chain (mhc appear to be indirect. This role is in direct contrast to that described in the larval muscles, where CF2 activates structural gene expression. The variation in myofibril phenotypes of CF2 mutants suggest the CF2 may have separate functions in fine-tuning expression of structural genes to insure proper filament stoichiometry, and monitoring and/or controlling the final myofibril size.

Filament heater current modulation for increased filament lifetime

International Nuclear Information System (INIS)

Paul, J.D.; Williams, H.E. III.

1996-01-01

The surface conversion H-minus ion source employs two 60 mil tungsten filaments which are approximately 17 centimeters in length. These filaments are heated to approximately 2,800 degrees centigrade by 95--100 amperes of DC heater current. The arc is struck at a 120 hertz rate, for 800 microseconds and is generally run at 30 amperes peak current. Although sputtering is considered a contributing factor in the demise of the filament, evaporation is of greater concern. If the peak arc current can be maintained with less average heater current, the filament evaporation rate for this arc current will diminish. In the vacuum of an ion source, the authors expect the filaments to retain much of their heat throughout a 1 millisecond (12% duty) loss of heater current. A circuit to eliminate 100 ampere heater currents from filaments during the arc pulse was developed. The magnetic field due to the 100 ampere current tends to hold electrons to the filament, decreasing the arc current. By eliminating this magnetic field, the arc should be more efficient, allowing the filaments to run at a lower average heater current. This should extend the filament lifetime. The circuit development and preliminary filament results are discussed

Structural and functional properties of chimeric EspA-FliCi filaments of EPEC.

Science.gov (United States)

Crepin, Valerie F; Martinez, Eric; Shaw, Robert K; Frankel, Gad; Daniell, Sarah J

2008-04-18

Enteropathogenic Escherichia coli utilise a filamentous type III secretion system to translocate effector proteins into host gut epithelial cells. The primary constituent of the extracellular component of the filamentous type III secretion system is EspA. This forms a long flexible helical conduit between the bacterium and host and has a structure almost identical to that of the flagella filament. We have inserted the D3 domain of FliCi (from Salmonella typhimurium) into the outer domain of EspA and have studied the structure and function of modified filaments when expressed in an enteropathogenic E. coli espA mutant. We found that the chimeric protein EspA-FliCi filaments were biologically active as they supported protein secretion and translocation [assessed by their ability to trigger actin polymerisation beneath adherent bacteria (fluorescent actin staining test)]. The expressed filaments were recognised by both EspA and FliCi antisera. Visualisation and analysis of the chimeric filaments by electron microscopy after negative staining showed that, remarkably, EspA filaments are able to tolerate a large protein insertion without a significant effect on their helical architecture.

Probabilities of filaments in a Poissonian distribution of points -I

International Nuclear Information System (INIS)

Betancort-Rijo, J.

1989-01-01

Statistical techniques are devised to assess the likelihood of a Poisson sample of points in two and three dimensions, containing specific filamentary structures. For that purpose, the expression of Otto et al (1986. Astrophys. J., 304) for the probability density of clumps in a Poissonian distribution of points is generalized for any value of the density contrast. A way of counting filaments differing from that of Otto et al. is proposed, because at low density contrast the filaments counted by Otto et al. are distributed in a clumpy fashion, each clump of filaments corresponding to a distinct observed filament. (author)

Expression of organophosphorus-degradation gene ( opd) in aggregating and non-aggregating filamentous nitrogen-fixing cyanobacteria

Science.gov (United States)

Li, Qiong; Tang, Qing; Xu, Xudong; Gao, Hong

2010-11-01

Genetic engineering in filamentous N2-fixing cyanobacteria usually involves Anabaena sp. PCC 7120 and several other non-aggregating species. Mass culture and harvest of such species are more energy consuming relative to aggregating species. To establish a gene transfer system for aggregating species, we tested many species of Anabaena and Nostoc, and identified Nostoc muscorum FACHB244 as a species that can be genetically manipulated using the conjugative gene transfer system. To promote biodegradation of organophosphorus pollutants in aquatic environments, we introduced a plasmid containing the organophosphorus-degradation gene ( opd) into Anabaena sp. PCC 7120 and Nostoc muscorum FACHB244 by conjugation. The opd gene was driven by a strong promoter, P psbA . From both species, we obtained transgenic strains having organophosphorus-degradation activities. At 25°C, the whole-cell activities of the transgenic Anabaena and Nostoc strains were 0.163±0.001 and 0.289±0.042 unit/μg Chl a, respectively. However, most colonies resulting from the gene transfer showed no activity. PCR and DNA sequencing revealed deletions or rearrangements in the plasmid in some of the colonies. Expression of the green fluorescent protein gene from the same promoter in Anabaena sp. PCC 7120 showed similar results. These results suggest that there is the potential to promote the degradation of organophosphorus pollutants with transgenic cyanobacteria and that selection of high-expression transgenic colonies is important for genetic engineering of Anabaena and Nostoc species. For the first time, we established a gene transfer and expression system in an aggregating filamentous N2-fixing cyanobacterium. The genetic manipulation system of Nostoc muscorum FACHB244 could be utilized in the elimination of pollutants and large-scale production of valuable proteins or metabolites.

Cadmium induces cadmium-tolerant gene expression in the filamentous fungus Trichoderma harzianum.

Science.gov (United States)

Cacciola, Santa O; Puglisi, Ivana; Faedda, Roberto; Sanzaro, Vincenzo; Pane, Antonella; Lo Piero, Angela R; Evoli, Maria; Petrone, Goffredo

2015-11-01

The filamentous fungus Trichoderma harzianum, strain IMI 393899, was able to grow in the presence of the heavy metals cadmium and mercury. The main objective of this research was to study the molecular mechanisms underlying the tolerance of the fungus T. harzianum to cadmium. The suppression subtractive hybridization (SSH) method was used for the characterization of the genes of T. harzianum implicated in cadmium tolerance compared with those expressed in the response to the stress induced by mercury. Finally, the effects of cadmium exposure were also validated by measuring the expression levels of the putative genes coding for a glucose transporter, a plasma membrane ATPase, a Cd(2+)/Zn(2+) transporter protein and a two-component system sensor histidine kinase YcbA, by real-time-PCR. By using the aforementioned SSH strategy, it was possible to identify 108 differentially expressed genes of the strain IMI 393899 of T. harzianum grown in a mineral substrate with the addition of cadmium. The expressed sequence tags identified by SSH technique were encoding different genes that may be involved in different biological processes, including those associated to primary and secondary metabolism, intracellular transport, transcription factors, cell defence, signal transduction, DNA metabolism, cell growth and protein synthesis. Finally, the results show that in the mechanism of tolerance to cadmium a possible signal transduction pathway could activate a Cd(2+)/Zn(2+) transporter protein and/or a plasma membrane ATPase that could be involved in the compartmentalization of cadmium inside the cell.

Candida krusei and Candida glabrata reduce the filamentation of Candida albicans by downregulating expression of HWP1 gene.

Science.gov (United States)

de Barros, Patrícia Pimentel; Freire, Fernanda; Rossoni, Rodnei Dennis; Junqueira, Juliana Campos; Jorge, Antonio Olavo Cardoso

2017-07-01

Pathogenicity of Candida albicans is associated with its capacity switch from yeast-like to hyphal growth. The hyphal form is capable to penetrate the epithelial surfaces and to damage the host tissues. Therefore, many investigations have focused on mechanisms that control the morphological transitions of C. albicans. Recently, certain studies have showed that non-albicans Candida species can reduce the capacity of C. albicans to form biofilms and to develop candidiasis in animal models. Then, the objective of this study was to evaluate the effects of Candida krusei and Candida glabrata on the morphogenesis of C. albicans. Firstly, the capacity of reference and clinical strains of C. albicans in forming hyphae was tested in vitro. After that, the expression of HWP1 (hyphal wall protein 1) gene was determined by quantitative real-time PCR (polymerase chain reaction) assay. For both reference and clinical strains, a significant inhibition of the hyphae formation was observed when C. albicans was incubated in the presence of C. krusei or C. glabrata compared to the control group composed only by C. albicans. In addition, the culture mixed of C. albicans-C. krusei or C. albicans-C. glabrata reduced significantly the expression of HWP1 gene of C. albicans in relation to single cultures of this specie. In both filamentation and gene expression assays, C. krusei showed the higher inhibitory activity on the morphogenesis of C. albicans compared to C. glabrata. C. krusei and C. glabrata are capable to reduce the filamentation of C. albicans and consequently decrease the expression of the HWP1 gene.

Altered expression of epithelial cell surface glycoconjugates and intermediate filaments at the margins of mucosal wounds

DEFF Research Database (Denmark)

Dabelsteen, Erik; Grøn, B.; Mandel, U.

1998-01-01

Alterations in cell to cell adhesion are necessary to enable the type of cell movements that are associated with epithelial wound healing and malignant invasion. Several studies of transformed cells have related epithelial cell movement to changes in the cell surface expression of the carbohydrate......-T antigen. The changes induced by wounding in the expression of collagen IV, laminin gamma2-chain (laminin-5), and laminin alpha5-chain were similar to those found in skin wounds and served to define the region of epithelial movement. This region was found to show a marked increase in staining for both...... epithelium, a pattern of expression similar to K16, which was also strongly upregulated in both the outgrowth and the adjacent nonwounded epithelium. These findings provide further support for an influence of such carbohydrate structures on the migratory behavior of epithelial cells....

Superresolution imaging of dynamic MreB filaments in B. subtilis--a multiple-motor-driven transport?

Science.gov (United States)

Olshausen, Philipp V; Defeu Soufo, Hervé Joël; Wicker, Kai; Heintzmann, Rainer; Graumann, Peter L; Rohrbach, Alexander

2013-09-03

The cytoskeletal protein MreB is an essential component of the bacterial cell-shape generation system. Using a superresolution variant of total internal reflection microscopy with structured illumination, as well as three-dimensional stacks of deconvolved epifluorescence microscopy, we found that inside living Bacillus subtilis cells, MreB forms filamentous structures of variable lengths, typically not longer than 1 μm. These filaments move along their orientation and mainly perpendicular to the long bacterial axis, revealing a maximal velocity at an intermediate length and a decreasing velocity with increasing filament length. Filaments move along straight trajectories but can reverse or alter their direction of propagation. Based on our measurements, we provide a mechanistic model that is consistent with all observations. In this model, MreB filaments mechanically couple several motors that putatively synthesize the cell wall, whereas the filaments' traces mirror the trajectories of the motors. On the basis of our mechanistic model, we developed a mathematical model that can explain the nonlinear velocity length dependence. We deduce that the coupling of cell wall synthesis motors determines the MreB filament transport velocity, and the filament mechanically controls a concerted synthesis of parallel peptidoglycan strands to improve cell wall stability. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Nonlinear Binormal Flow of Vortex Filaments

Science.gov (United States)

Strong, Scott; Carr, Lincoln

2015-11-01

With the current advances in vortex imaging of Bose-Einstein condensates occurring at the Universities of Arizona, São Paulo and Cambridge, interest in vortex filament dynamics is experiencing a resurgence. Recent simulations, Salman (2013), depict dissipative mechanisms resulting from vortex ring emissions and Kelvin wave generation associated with vortex self-intersections. As the local induction approximation fails to capture reconnection events, it lacks a similar dissipative mechanism. On the other hand, Strong&Carr (2012) showed that the exact representation of the velocity field induced by a curved segment of vortex contains higher-order corrections expressed in powers of curvature. This nonlinear binormal flow can be transformed, Hasimoto (1972), into a fully nonlinear equation of Schrödinger type. Continued transformation, Madelung (1926), reveals that the filament's square curvature obeys a quasilinear scalar conservation law with source term. This implies a broader range of filament dynamics than is possible with the integrable linear binormal flow. In this talk we show the affect higher-order corrections have on filament dynamics and discuss physical scales for which they may be witnessed in future experiments. Partially supported by NSF.

Mutation-specific effects on thin filament length in thin filament myopathy.

Science.gov (United States)

Winter, Josine M de; Joureau, Barbara; Lee, Eun-Jeong; Kiss, Balázs; Yuen, Michaela; Gupta, Vandana A; Pappas, Christopher T; Gregorio, Carol C; Stienen, Ger J M; Edvardson, Simon; Wallgren-Pettersson, Carina; Lehtokari, Vilma-Lotta; Pelin, Katarina; Malfatti, Edoardo; Romero, Norma B; Engelen, Baziel G van; Voermans, Nicol C; Donkervoort, Sandra; Bönnemann, C G; Clarke, Nigel F; Beggs, Alan H; Granzier, Henk; Ottenheijm, Coen A C

2016-06-01

Thin filament myopathies are among the most common nondystrophic congenital muscular disorders, and are caused by mutations in genes encoding proteins that are associated with the skeletal muscle thin filament. Mechanisms underlying muscle weakness are poorly understood, but might involve the length of the thin filament, an important determinant of force generation. We investigated the sarcomere length-dependence of force, a functional assay that provides insights into the contractile strength of muscle fibers as well as the length of the thin filaments, in muscle fibers from 51 patients with thin filament myopathy caused by mutations in NEB, ACTA1, TPM2, TPM3, TNNT1, KBTBD13, KLHL40, and KLHL41. Lower force generation was observed in muscle fibers from patients of all genotypes. In a subset of patients who harbor mutations in NEB and ACTA1, the lower force was associated with downward shifted force-sarcomere length relations, indicative of shorter thin filaments. Confocal microscopy confirmed shorter thin filaments in muscle fibers of these patients. A conditional Neb knockout mouse model, which recapitulates thin filament myopathy, revealed a compensatory mechanism; the lower force generation that was associated with shorter thin filaments was compensated for by increasing the number of sarcomeres in series. This allowed muscle fibers to operate at a shorter sarcomere length and maintain optimal thin-thick filament overlap. These findings might provide a novel direction for the development of therapeutic strategies for thin filament myopathy patients with shortened thin filament lengths. Ann Neurol 2016;79:959-969. © 2016 American Neurological Association.

Intermediate Monocytes but Not TIE2-Expressing Monocytes Are a Sensitive Diagnostic Indicator for Colorectal Cancer

Science.gov (United States)

Schauer, Dominic; Starlinger, Patrick; Reiter, Christian; Jahn, Nikolaus; Zajc, Philipp; Buchberger, Elisabeth; Bachleitner-Hofmann, Thomas; Bergmann, Michael; Stift, Anton; Gruenberger, Thomas; Brostjan, Christine

2012-01-01

We have conducted the first study to determine the diagnostic potential of the CD14++CD16+ intermediate monocytes as compared to the pro-angiogenic subset of CD14++CD16+TIE2+ TIE2-expressing monocytes (TEMs) in cancer. These monocyte populations were investigated by flow cytometry in healthy volunteers (N = 32) and in colorectal carcinoma patients with localized (N = 24) or metastatic (N = 37) disease. We further determined blood levels of cytokines associated with monocyte regulation. The results revealed the intermediate monocyte subset to be significantly elevated in colorectal cancer patients and to show the highest frequencies in localized disease. Multivariate regression analysis identified intermediate monocytes as a significant independent variable in cancer prediction. With a cut-off value at 0.37% (intermediate monocytes of total leukocytes) the diagnostic sensitivity and specificity ranged at 69% and 81%, respectively. In contrast, TEM levels were elevated in localized cancer but did not differ significantly between groups and none of the cytokines correlated with monocyte subpopulations. Of interest, in vitro analyses supported the observation that intermediate monocytes were more potently induced by primary as opposed to metastatic cancer cells which may relate to the immunosuppressive milieu established in the advanced stage of metastatic disease. In conclusion, intermediate monocytes as compared to TIE2-expressing monocytes are a more sensitive diagnostic indicator of colorectal cancer. PMID:22973451

Intermediate monocytes but not TIE2-expressing monocytes are a sensitive diagnostic indicator for colorectal cancer.

Directory of Open Access Journals (Sweden)

Dominic Schauer

Full Text Available We have conducted the first study to determine the diagnostic potential of the CD14++CD16+ intermediate monocytes as compared to the pro-angiogenic subset of CD14++CD16+TIE2+ TIE2-expressing monocytes (TEMs in cancer. These monocyte populations were investigated by flow cytometry in healthy volunteers (N = 32 and in colorectal carcinoma patients with localized (N = 24 or metastatic (N = 37 disease. We further determined blood levels of cytokines associated with monocyte regulation. The results revealed the intermediate monocyte subset to be significantly elevated in colorectal cancer patients and to show the highest frequencies in localized disease. Multivariate regression analysis identified intermediate monocytes as a significant independent variable in cancer prediction. With a cut-off value at 0.37% (intermediate monocytes of total leukocytes the diagnostic sensitivity and specificity ranged at 69% and 81%, respectively. In contrast, TEM levels were elevated in localized cancer but did not differ significantly between groups and none of the cytokines correlated with monocyte subpopulations. Of interest, in vitro analyses supported the observation that intermediate monocytes were more potently induced by primary as opposed to metastatic cancer cells which may relate to the immunosuppressive milieu established in the advanced stage of metastatic disease. In conclusion, intermediate monocytes as compared to TIE2-expressing monocytes are a more sensitive diagnostic indicator of colorectal cancer.

EST Table: BP125370 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available 10 56 %/150 aa gi|189241063|ref|XP_967018.2| PREDICTED: similar to restin (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Tribolium castaneum] FS906662 fbpv ... ...n (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Tribolium castaneum] 10/08/29 55...BP125370 fbpv0758 10/09/28 56 %/150 aa ref|XP_967018.2| PREDICTED: similar to resti

Lateral motion and bending of microtubules studied with a new single-filament tracking routine in living cells.

Science.gov (United States)

Pallavicini, Carla; Levi, Valeria; Wetzler, Diana E; Angiolini, Juan F; Benseñor, Lorena; Despósito, Marcelo A; Bruno, Luciana

2014-06-17

The cytoskeleton is involved in numerous cellular processes such as migration, division, and contraction and provides the tracks for transport driven by molecular motors. Therefore, it is very important to quantify the mechanical behavior of the cytoskeletal filaments to get a better insight into cell mechanics and organization. It has been demonstrated that relevant mechanical properties of microtubules can be extracted from the analysis of their motion and shape fluctuations. However, tracking individual filaments in living cells is extremely complex due, for example, to the high and heterogeneous background. We introduce a believed new tracking algorithm that allows recovering the coordinates of fluorescent microtubules with ∼9 nm precision in in vitro conditions. To illustrate potential applications of this algorithm, we studied the curvature distributions of fluorescent microtubules in living cells. By performing a Fourier analysis of the microtubule shapes, we found that the curvatures followed a thermal-like distribution as previously reported with an effective persistence length of ∼20 μm, a value significantly smaller than that measured in vitro. We also verified that the microtubule-associated protein XTP or the depolymerization of the actin network do not affect this value; however, the disruption of intermediate filaments decreased the persistence length. Also, we recovered trajectories of microtubule segments in actin or intermediate filament-depleted cells, and observed a significant increase of their motion with respect to untreated cells showing that these filaments contribute to the overall organization of the microtubule network. Moreover, the analysis of trajectories of microtubule segments in untreated cells showed that these filaments presented a slower but more directional motion in the cortex with respect to the perinuclear region, and suggests that the tracking routine would allow mapping the microtubule dynamical organization in cells

Superresolution Imaging of Dynamic MreB Filaments in B. subtilis—A Multiple-Motor-Driven Transport?

Science.gov (United States)

Olshausen, Philipp v.; Defeu Soufo, Hervé Joël; Wicker, Kai; Heintzmann, Rainer; Graumann, Peter L.; Rohrbach, Alexander

2013-01-01

The cytoskeletal protein MreB is an essential component of the bacterial cell-shape generation system. Using a superresolution variant of total internal reflection microscopy with structured illumination, as well as three-dimensional stacks of deconvolved epifluorescence microscopy, we found that inside living Bacillus subtilis cells, MreB forms filamentous structures of variable lengths, typically not longer than 1 μm. These filaments move along their orientation and mainly perpendicular to the long bacterial axis, revealing a maximal velocity at an intermediate length and a decreasing velocity with increasing filament length. Filaments move along straight trajectories but can reverse or alter their direction of propagation. Based on our measurements, we provide a mechanistic model that is consistent with all observations. In this model, MreB filaments mechanically couple several motors that putatively synthesize the cell wall, whereas the filaments’ traces mirror the trajectories of the motors. On the basis of our mechanistic model, we developed a mathematical model that can explain the nonlinear velocity length dependence. We deduce that the coupling of cell wall synthesis motors determines the MreB filament transport velocity, and the filament mechanically controls a concerted synthesis of parallel peptidoglycan strands to improve cell wall stability. PMID:24010660

Myosin isoform switching during assembly of the Drosophila flight muscle thick filament lattice.

Science.gov (United States)

Orfanos, Zacharias; Sparrow, John C

2013-01-01

During muscle development myosin molecules form symmetrical thick filaments, which integrate with the thin filaments to produce the regular sarcomeric lattice. In Drosophila indirect flight muscles (IFMs) the details of this process can be studied using genetic approaches. The weeP26 transgenic line has a GFP-encoding exon inserted into the single Drosophila muscle myosin heavy chain gene, Mhc. The weeP26 IFM sarcomeres have a unique MHC-GFP-labelling pattern restricted to the sarcomere core, explained by non-translation of the GFP exon following alternative splicing. Characterisation of wild-type IFM MHC mRNA confirmed the presence of an alternately spliced isoform, expressed earlier than the major IFM-specific isoform. The two wild-type IFM-specific MHC isoforms differ by the presence of a C-terminal 'tailpiece' in the minor isoform. The sequential expression and assembly of these two MHCs into developing thick filaments suggest a role for the tailpiece in initiating A-band formation. The restriction of the MHC-GFP sarcomeric pattern in weeP26 is lifted when the IFM lack the IFM-specific myosin binding protein flightin, suggesting that it limits myosin dissociation from thick filaments. Studies of flightin binding to developing thick filaments reveal a progressive binding at the growing thick filament tips and in a retrograde direction to earlier assembled, proximal filament regions. We propose that this flightin binding restricts myosin molecule incorporation/dissociation during thick filament assembly and explains the location of the early MHC isoform pattern in the IFM A-band.

Interplay between Solo and keratin filaments is crucial for mechanical force–induced stress fiber reinforcement

Science.gov (United States)

Fujiwara, Sachiko; Ohashi, Kazumasa; Mashiko, Toshiya; Kondo, Hiroshi; Mizuno, Kensaku

2016-01-01

Mechanical force–induced cytoskeletal reorganization is essential for cell and tissue remodeling and homeostasis; however, the underlying cellular mechanisms remain elusive. Solo (ARHGEF40) is a RhoA-targeting guanine nucleotide exchange factor (GEF) involved in cyclical stretch–induced human endothelial cell reorientation and convergent extension cell movement in zebrafish gastrula. In this study, we show that Solo binds to keratin-8/keratin-18 (K8/K18) intermediate filaments through multiple sites. Solo overexpression promotes the formation of thick actin stress fibers and keratin bundles, whereas knockdown of Solo, expression of a GEF-inactive mutant of Solo, or inhibition of ROCK suppresses stress fiber formation and leads to disorganized keratin networks, indicating that the Solo-RhoA-ROCK pathway serves to precisely organize keratin networks, as well as to promote stress fibers. Of importance, knockdown of Solo or K18 or overexpression of GEF-inactive or deletion mutants of Solo suppresses tensile force–induced stress fiber reinforcement. Furthermore, knockdown of Solo or K18 suppresses tensile force-induced RhoA activation. These results strongly suggest that the interplay between Solo and K8/K18 filaments plays a crucial role in tensile force–induced RhoA activation and consequent actin cytoskeletal reinforcement. PMID:26823019

The importance of subfragment 2 and C-terminus of myosin heavy chain for thick filament assembly in skeletal muscle cells.

Science.gov (United States)

Ojima, Koichi; Oe, Mika; Nakajima, Ikuyo; Shibata, Masahiro; Muroya, Susumu; Chikuni, Koichi; Hattori, Akihito; Nishimura, Takanori

2015-04-01

In skeletal muscle cells, myofibrillar proteins are highly organized into sarcomeres in which thick filaments interdigitate with thin filaments to generate contractile force. The size of thick filaments, which consist mainly of myosin molecules, is strictly controlled. However, little is known about the mechanisms by which myosin molecules assemble into thick filaments. Here, we assessed the ability of each domain of myosin heavy chain (Myh) to form thick filaments. We showed that exogenously expressed subfragment 2 (S2) + light meromyosin (LMM) of Myh was efficiently incorporated into thick filaments in muscle cells, although neither solely expressed S2 nor LMM targeted to thick filaments properly. In nonmuscle COS7 cells, S2+LMM formed more enlarged filaments/speckles than LMM. These results suggest that Myh filament formation is induced by S2 accompanying LMM. We further examined the effects of Myh C-terminus on thick filament assembly. C-terminal deletion mutants were incorporated not into entire thick filaments but rather into restricted regions of thick filaments. Our findings suggest that the elongation of myosin filaments to form thick filaments is regulated by S2 as well as C-terminus of LMM. © 2014 Japanese Society of Animal Science.

Ca2+ improves organization of single-stranded DNA bases in human Rad51 filament, explaining stimulatory effect on gene recombination.

KAUST Repository

Fornander, Louise H

2012-02-22

Human RAD51 protein (HsRad51) catalyses the DNA strand exchange reaction for homologous recombination. To clarify the molecular mechanism of the reaction in vitro being more effective in the presence of Ca(2+) than of Mg(2+), we have investigated the effect of these ions on the structure of HsRad51 filament complexes with single- and double-stranded DNA, the reaction intermediates. Flow linear dichroism spectroscopy shows that the two ionic conditions induce significantly different structures in the HsRad51/single-stranded DNA complex, while the HsRad51/double-stranded DNA complex does not demonstrate this ionic dependence. In the HsRad51/single-stranded DNA filament, the primary intermediate of the strand exchange reaction, ATP/Ca(2+) induces an ordered conformation of DNA, with preferentially perpendicular orientation of nucleobases relative to the filament axis, while the presence of ATP/Mg(2+), ADP/Mg(2+) or ADP/Ca(2+) does not. A high strand exchange activity is observed for the filament formed with ATP/Ca(2+), whereas the other filaments exhibit lower activity. Molecular modelling suggests that the structural variation is caused by the divalent cation interfering with the L2 loop close to the DNA-binding site. It is proposed that the larger Ca(2+) stabilizes the loop conformation and thereby the protein-DNA interaction. A tight binding of DNA, with bases perpendicularly oriented, could facilitate strand exchange.

Filamentary structures in dense plasma focus: Current filaments or vortex filaments?

Energy Technology Data Exchange (ETDEWEB)

Soto, Leopoldo, E-mail: lsoto@cchen.cl; Pavez, Cristian; Moreno, José [Comisión Chilena de Energía Nuclear, CCHEN, Casilla 188-D, Santiago (Chile); Center for Research and Applications in Plasma Physics and Pulsed Power, P4, Departamento de Ciencias Físicas, Facultad de Ciencias Exactas, Universidad Andrés Bello, República 220, Santiago (Chile); Castillo, Fermin [Universidad Nacional Autónoma de México, Cuernavaca, México (Mexico); Veloso, Felipe [Instituto de Física, Pontificia Universidad Católica de Chile, 7820436 Santiago (Chile); Auluck, S. K. H. [Bhabha Atomic Research Center, Mumbai 400 085 (India)

2014-07-15

Recent observations of an azimuthally distributed array of sub-millimeter size sources of fusion protons and correlation between extreme ultraviolet (XUV) images of filaments with neutron yield in PF-1000 plasma focus have re-kindled interest in their significance. These filaments have been described variously in literature as current filaments and vortex filaments, with very little experimental evidence in support of either nomenclature. This paper provides, for the first time, experimental observations of filaments on a table-top plasma focus device using three techniques: framing photography of visible self-luminosity from the plasma, schlieren photography, and interferometry. Quantitative evaluation of density profile of filaments from interferometry reveals that their radius closely agrees with the collision-less ion skin depth. This is a signature of relaxed state of a Hall fluid, which has significant mass flow with equipartition between kinetic and magnetic energy, supporting the “vortex filament” description. This interpretation is consistent with empirical evidence of an efficient energy concentration mechanism inferred from nuclear reaction yields.

Filament Activation in Response to Magnetic Flux Emergence and Cancellation in Filament Channels

Science.gov (United States)

Li, Ting; Zhang, Jun; Ji, Haisheng

2015-06-01

We conducted a comparative analysis of two filaments that showed a quite different activation in response to the flux emergence within the filament channels. The observations from the Solar Dynamics Observatory (SDO) and Global Oscillation Network Group (GONG) were made to analyze the two filaments on 2013 August 17 - 20 (SOL2013-08-17) and September 29 (SOL2013-09-29). The first event showed that the main body of the filament was separated into two parts when an active region (AR) emerged with a maximum magnetic flux of about 6.4×1021 Mx underlying the filament. The close neighborhood and common direction of the bright threads in the filament and the open AR fan loops suggest a similar magnetic connectivity of these two flux systems. The equilibrium of the filament was not destroyed three days after the start of the emergence of the AR. To our knowledge, similar observations have never been reported before. In the second event, the emerging flux occurred nearby a barb of the filament with a maximum magnetic flux of 4.2×1020 Mx, about one order of magnitude lower than that of the first event. Two patches of parasitic polarity in the vicinity of the barb merged, then cancelled with nearby network fields. About 20 hours after the onset of the emergence, the filament erupted. Our findings imply that the location of emerging flux within the filament channel is probably crucial to filament evolution. If the flux emergence appears nearby the barbs, it is highly likely that the emerging flux and the filament magnetic fields will cancel, which may lead to the eruption of the filament. The comparison of the two events shows that the emergence of a small AR may still not be enough to disrupt the stability of a filament system, and the actual eruption only occurs after the flux cancellation sets in.

A symplectic integration method for elastic filaments

Science.gov (United States)

Ladd, Tony; Misra, Gaurav

2009-03-01

Elastic rods are a ubiquitous coarse-grained model of semi-flexible biopolymers such as DNA, actin, and microtubules. The Worm-Like Chain (WLC) is the standard numerical model for semi-flexible polymers, but it is only a linearized approximation to the dynamics of an elastic rod, valid for small deflections; typically the torsional motion is neglected as well. In the standard finite-difference and finite-element formulations of an elastic rod, the continuum equations of motion are discretized in space and time, but it is then difficult to ensure that the Hamiltonian structure of the exact equations is preserved. Here we discretize the Hamiltonian itself, expressed as a line integral over the contour of the filament. This discrete representation of the continuum filament can then be integrated by one of the explicit symplectic integrators frequently used in molecular dynamics. The model systematically approximates the continuum partial differential equations, but has the same level of computational complexity as molecular dynamics and is constraint free. Numerical tests show that the algorithm is much more stable than a finite-difference formulation and can be used for high aspect ratio filaments, such as actin. We present numerical results for the deterministic and stochastic motion of single filaments.

Large amplitude oscillatory motion along a solar filament

Science.gov (United States)

Vršnak, B.; Veronig, A. M.; Thalmann, J. K.; Žic, T.

2007-08-01

Context: Large amplitude oscillations of solar filaments is a phenomenon that has been known for more than half a century. Recently, a new mode of oscillations, characterized by periodical plasma motions along the filament axis, was discovered. Aims: We analyze such an event, recorded on 23 January 2002 in Big Bear Solar Observatory Hα filtergrams, to infer the triggering mechanism and the nature of the restoring force. Methods: Motion along the filament axis of a distinct buldge-like feature was traced, to quantify the kinematics of the oscillatory motion. The data were fitted by a damped sine function to estimate the basic parameters of the oscillations. To identify the triggering mechanism, morphological changes in the vicinity of the filament were analyzed. Results: The observed oscillations of the plasma along the filament were characterized by an initial displacement of 24 Mm, an initial velocity amplitude of 51 km s-1, a period of 50 min, and a damping time of 115 min. We interpret the trigger in terms of poloidal magnetic flux injection by magnetic reconnection at one of the filament legs. The restoring force is caused by the magnetic pressure gradient along the filament axis. The period of oscillations, derived from the linearized equation of motion (harmonic oscillator) can be expressed as P=π√{2}L/v_Aϕ≈4.4L/v_Aϕ, where v_Aϕ =Bϕ0/√μ_0ρ represents the Alfvén speed based on the equilibrium poloidal field Bϕ0. Conclusions: Combination of our measurements with some previous observations of the same kind of oscillations shows good agreement with the proposed interpretation. Movie to Fig. 1 is only available in electronic form at http://www.aanda.org

Actin filaments – a target for redox regulation

Science.gov (United States)

Wilson, Carlos; Terman, Jonathan R.; González-Billault, Christian; Ahmed, Giasuddin

2016-01-01

Actin and its ability to polymerize into dynamic filaments is critical for the form and function of cells throughout the body. While multiple proteins have been characterized as affecting actin dynamics through non-covalent means, actin and its protein regulators are also susceptible to covalent modifications of their amino acid residues. In this regard, oxidation-reduction (Redox) intermediates have emerged as key modulators of the actin cytoskeleton with multiple different effects on cellular form and function. Here, we review work implicating Redox intermediates in post-translationally altering actin and discuss what is known regarding how these alterations affect the properties of actin. We also focus on two of the best characterized enzymatic sources of these Redox intermediates – the NADPH oxidase NOX and the flavoprotein monooxygenase MICAL – and detail how they have both been identified as altering actin, but share little similarity and employ different means to regulate actin dynamics. Finally, we discuss the role of these enzymes and redox signaling in regulating the actin cytoskeleton in vivo and highlight their importance for neuronal form and function in health and disease. PMID:27309342

Nonlinear Force-free Field Extrapolation of a Coronal Magnetic Flux Rope Supporting a Large-scale Solar Filament from a Photospheric Vector Magnetogram

Science.gov (United States)

Jiang, Chaowei; Wu, S. T.; Feng, Xueshang; Hu, Qiang

2014-05-01

Solar filaments are commonly thought to be supported in magnetic dips, in particular, in those of magnetic flux ropes (FRs). In this Letter, based on the observed photospheric vector magnetogram, we implement a nonlinear force-free field (NLFFF) extrapolation of a coronal magnetic FR that supports a large-scale intermediate filament between an active region and a weak polarity region. This result is a first, in the sense that current NLFFF extrapolations including the presence of FRs are limited to relatively small-scale filaments that are close to sunspots and along main polarity inversion lines (PILs) with strong transverse field and magnetic shear, and the existence of an FR is usually predictable. In contrast, the present filament lies along the weak-field region (photospheric field strength barbs very well, which strongly supports the FR-dip model for filaments. The filament is stably sustained because the FR is weakly twisted and strongly confined by the overlying closed arcades.

Filament Substructures and their Interrelation

Science.gov (United States)

Lin, Y.; Martin, S. F.; Engvold, O.

The main structural components of solar filaments, their spines, barbs, and legs at the extreme ends of the spine, are illustrated from recent high-resolution observations. The thread-like structures appear to be present in filaments everywhere and at all times. They are the fundamental elements of solar filaments. The interrelation of the spines, barbs and legs are discussed. From observations, we present a conceptual model of the magnetic field of a filament. We suggest that only a single physical model is needed to explain filaments in a continuous spectrum represented by active region filaments at one end and quiescent filaments at the other end.

Methods for monitoring multiple gene expression

Energy Technology Data Exchange (ETDEWEB)

Berka, Randy [Davis, CA; Bachkirova, Elena [Davis, CA; Rey, Michael [Davis, CA

2012-05-01

The present invention relates to methods for monitoring differential expression of a plurality of genes in a first filamentous fungal cell relative to expression of the same genes in one or more second filamentous fungal cells using microarrays containing Trichoderma reesei ESTs or SSH clones, or a combination thereof. The present invention also relates to computer readable media and substrates containing such array features for monitoring expression of a plurality of genes in filamentous fungal cells.

Methods for monitoring multiple gene expression

Energy Technology Data Exchange (ETDEWEB)

Berka, Randy; Bachkirova, Elena; Rey, Michael

2013-10-01

The present invention relates to methods for monitoring differential expression of a plurality of genes in a first filamentous fungal cell relative to expression of the same genes in one or more second filamentous fungal cells using microarrays containing Trichoderma reesei ESTs or SSH clones, or a combination thereof. The present invention also relates to computer readable media and substrates containing such array features for monitoring expression of a plurality of genes in filamentous fungal cells.

A core filamentation response network in Candida albicans is restricted to eight genes.

Directory of Open Access Journals (Sweden)

Ronny Martin

Full Text Available Although morphological plasticity is a central virulence trait of Candida albicans, the number of filament-associated genes and the interplay of mechanisms regulating their expression remain unknown. By correlation-based network modeling of the transcriptional response to different defined external stimuli for morphogenesis we identified a set of eight genes with highly correlated expression patterns, forming a core filamentation response. This group of genes included ALS3, ECE1, HGT2, HWP1, IHD1 and RBT1 which are known or supposed to encode for cell- wall associated proteins as well as the Rac1 guanine nucleotide exchange factor encoding gene DCK1 and the unknown function open reading frame orf19.2457. The validity of network modeling was confirmed using a dataset of advanced complexity that describes the transcriptional response of C. albicans during epithelial invasion as well as comparing our results with other previously published transcriptome studies. Although the set of core filamentation response genes was quite small, several transcriptional regulators are involved in the control of their expression, depending on the environmental condition.

BnEPFL6, an EPIDERMAL PATTERNING FACTOR-LIKE (EPFL) secreted peptide gene, is required for filament elongation in Brassica napus.

Science.gov (United States)

Huang, Yi; Tao, Zhangsheng; Liu, Qiong; Wang, Xinfa; Yu, Jingyin; Liu, Guihua; Wang, Hanzhong

2014-07-01

Inflorescence architecture, pedicel length and stomata patterning in Arabidopsis thaliana are specified by inter-tissue communication mediated by ERECTA and its signaling ligands in the EPIDERMAL PATTERNING FACTOR-LIKE (EPFL) family of secreted cysteine-rich peptides. Here, we identified and characterized BnEPFL6 from Brassica napus. Heterologous expression of this gene under the double enhanced CaMV promoter (D35S) in Arabidopsis resulted in shortened stamen filaments, filaments degradation, and reduced filament cell size that displayed down-regulated expression of AHK2, in which phenotypic variation of ahk2-1 mutant presented highly consistent with that of BnEPFL6 transgenic lines. Especially, the expression level of BnEPFL6 in the shortened filaments of four B. napus male sterile lines (98A, 86A, SA, and Z11A) was similar to that of BnEPFL6 in the transgenic Arabidopsis lines. The activity of pBnEPFL6.2::GUS was intensive in the filaments of transgenic lines. These observations reveal that BnEPFL6 plays an important role in filament elongation and may also affect organ morphology and floral organ specification via a BnEPFL6-mediated cascade.

SYMPATHETIC SOLAR FILAMENT ERUPTIONS

Energy Technology Data Exchange (ETDEWEB)

Wang, Rui; Liu, Ying D.; Zimovets, Ivan; Hu, Huidong; Yang, Zhongwei [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Dai, Xinghua, E-mail: liuxying@spaceweather.ac.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2016-08-10

The 2015 March 15 coronal mass ejection as one of the two that together drove the largest geomagnetic storm of solar cycle 24 so far was associated with sympathetic filament eruptions. We investigate the relations between the different filaments involved in the eruption. A surge-like small-scale filament motion is confirmed as the trigger that initiated the erupting filament with multi-wavelength observations and using a forced magnetic field extrapolation method. When the erupting filament moved to an open magnetic field region, it experienced an obvious acceleration process and was accompanied by a C-class flare and the rise of another larger filament that eventually failed to erupt. We measure the decay index of the background magnetic field, which presents a critical height of 118 Mm. Combining with a potential field source surface extrapolation method, we analyze the distributions of the large-scale magnetic field, which indicates that the open magnetic field region may provide a favorable condition for F2 rapid acceleration and have some relation with the largest solar storm. The comparison between the successful and failed filament eruptions suggests that the confining magnetic field plays an important role in the preconditions for an eruption.

Modern filaments for composite materials

International Nuclear Information System (INIS)

Krivelli-Viskonti, I.

1982-01-01

Analysis of modern state and ways to improve properties of different filaments for the forecast of the filament application in composite materials has been conducted. In the near future as before the greatest attention will be paid to fibre glass, as this material is widely used in the reinforcing of organic matrices. Carbon and kevlar filaments are the most prospective ones. For the service at medium, high or superhigh temperatures selection of matrix material is more significant than selection of filament. Organic matrices can not be used at temperatures > 250 deg C: this is already the range of metal matrix application. Though at temperatures above room one many filaments can be used, boron filaments and metal wire are the only reinforcing materials, inspite of the fact that carbon filaments are successfully used for metal matrix reinforcing. At very high temperatures only carbon filaments or silicon carbide ones can be used, but their cost is very high and besides economical problems there are many difficulties of technical character

Assembly of MreB filaments on liposome membranes: a synthetic biology approach.

Science.gov (United States)

Maeda, Yusuke T; Nakadai, Tomoyoshi; Shin, Jonghyeon; Uryu, Kunihiro; Noireaux, Vincent; Libchaber, Albert

2012-02-17

The physical interaction between the cytoskeleton and the cell membrane is essential in defining the morphology of living organisms. In this study, we use a synthetic approach to polymerize bacterial MreB filaments inside phospholipid vesicles. When the proteins MreB and MreC are expressed inside the liposomes, the MreB cytoskeleton structure develops at the inner membrane. Furthermore, when purified MreB is used inside the liposomes, MreB filaments form a 4-10 μm rigid bundle structure and deform the lipid vesicles in physical contact with the vesicle inner membrane. These results indicate that the fibrillation of MreB filaments can take place either in close proximity of deformable lipid membrane or in the presence of associated protein. Our finding might be relevant for the self-assembly of cytoskeleton filaments toward the construction of artificial cell systems.

Solar Filament Extraction and Characterizing

Science.gov (United States)

Yuan, Yuan; Shih, F. Y.; Jing, J.; Wang, H.

2010-05-01

This paper presents a new method to extract and characterize solar filaments from H-alpha full-disk images produced by Big Bear Solar Observatory. A cascading Hough Transform method is designed to identify solar disk center location and radius. Solar disks are segmented from the background, and unbalanced illumination on the surface of solar disks is removed using polynomial surface fitting. And then a localized adaptive thresholding is employed to extract solar filament candidates. After the removal of small solar filament candidates, the remaining larger candidates are used as the seeds of region growing. The procedure of region growing not only connects broken filaments but also generate complete shape for each filament. Mathematical morphology thinning is adopted to produce the skeleton of each filament, and graph theory is used to prune branches and barbs to get the main skeleton. The length and the location of the main skeleton is characterized. The proposed method can help scientists and researches study the evolution of solar filament, for instance, to detect solar filament eruption. The presented method has already been used by Space Weather Research Lab of New Jersey Institute of Technology (http://swrl.njit.edu) to generate the solar filament online catalog using H-alpha full-disk images of Global H-alpha Network (http://swrl.njit.edu/ghn_web/).

Temporal symmetry of individual filaments in different spatial symmetry filaments pattern in a dielectric barrier discharge

International Nuclear Information System (INIS)

Dong, L. F.; Xiao, H.; Fan, W. L.; Yin, Z. Q.; Zhao, H. T.

2010-01-01

The temporal behavior of individual filament in different spatial symmetry filaments patterns in dielectric barrier discharge is investigated by using an optical method. A series of return maps of the discharge moments of individual filaments is given. It is found that the temporal symmetry of individual filament changes with the change of the spatial symmetry of filaments pattern as the applied voltage increases. The role of wall charges for this phenomenon is analyzed.

Magnetic helicity and active filament configuration

Science.gov (United States)

Romano, P.; Zuccarello, F.; Poedts, S.; Soenen, A.; Zuccarello, F. P.

2009-11-01

Context: The role of magnetic helicity in active filament formation and destabilization is still under debate. Aims: Although active filaments usually show a sigmoid shape and a twisted configuration before and during their eruption, it is unclear which mechanism leads to these topologies. In order to provide an observational contribution to clarify these issues, we describe a filament evolution whose characteristics seem to be directly linked to the magnetic helicity transport in corona. Methods: We applied different methods to determine the helicity sign and the chirality of the filament magnetic field. We also computed the magnetic helicity transport rate at the filament footpoints. Results: All the observational signatures provided information on the positive helicity and sinistral chirality of the flux rope containing the filament material: its forward S shape, the orientation of its barbs, the bright and dark threads at 195 Å. Moreover, the magnetic helicity transport rate at the filament footpoints showed a clear accumulation of positive helicity. Conclusions: The study of this event showed a correspondence between several signatures of the sinistral chirality of the filament and several evidences of the positive magnetic helicity of the filament magnetic field. We also found that the magnetic helicity transported along the filament footpoints showed an increase just before the change of the filament shape observed in Hα images. We argued that the photospheric regions where the filament was rooted might be the preferential ways where the magnetic helicity was injected along the filament itself and where the conditions to trigger the eruption were yielded.

Femtosecond Laser Filamentation

CERN Document Server

Chin, See Leang

2010-01-01

Femtosecond Laser Filamentation gives a comprehensive review of the physics of propagation of intense femtosecond laser pulses in optical media (principally air) and the applications and challenges of this new technique. This book presents the modern understanding of the physics of femtosecond laser pulse propagation, including unusual new effects such as the self-transformation of the pulse into a white light laser pulse, intensity clamping, the physics of multiple filamentation and competition, and how filaments’ ability to melt glass leads to wave guide writing. The potential applications of laser filamentation in atmospheric sensing and the generation of other electromagnetic pulses from the UV to the radio frequency are treated, together with possible future challenges in the excitation of super-excited states of molecules. Exciting new phenomena such as filament induced ultrafast birefringence and the excitation of molecular rotational wave packets and their multiple revivals in air (gases) will also ...

Bacillus subtilis MreB orthologs self-organize into filamentous structures underneath the cell membrane in a heterologous cell system.

Directory of Open Access Journals (Sweden)

Felix Dempwolff

Full Text Available Actin-like bacterial cytoskeletal element MreB has been shown to be essential for the maintenance of rod cell shape in many bacteria. MreB forms rapidly remodelling helical filaments underneath the cell membrane in Bacillus subtilis and in other bacterial cells, and co-localizes with its two paralogs, Mbl and MreBH. We show that MreB localizes as dynamic bundles of filaments underneath the cell membrane in Drosophila S2 Schneider cells, which become highly stable when the ATPase motif in MreB is modified. In agreement with ATP-dependent filament formation, the depletion of ATP in the cells lead to rapid dissociation of MreB filaments. Extended induction of MreB resulted in the formation of membrane protrusions, showing that like actin, MreB can exert force against the cell membrane. Mbl also formed membrane associated filaments, while MreBH formed filaments within the cytosol. When co-expressed, MreB, Mbl and MreBH built up mixed filaments underneath the cell membrane. Membrane protein RodZ localized to endosomes in S2 cells, but localized to the cell membrane when co-expressed with Mbl, showing that bacterial MreB/Mbl structures can recruit a protein to the cell membrane. Thus, MreB paralogs form a self-organizing and dynamic filamentous scaffold underneath the membrane that is able to recruit other proteins to the cell surface.

Bacillus subtilis MreB orthologs self-organize into filamentous structures underneath the cell membrane in a heterologous cell system.

Science.gov (United States)

Dempwolff, Felix; Reimold, Christian; Reth, Michael; Graumann, Peter L

2011-01-01

Actin-like bacterial cytoskeletal element MreB has been shown to be essential for the maintenance of rod cell shape in many bacteria. MreB forms rapidly remodelling helical filaments underneath the cell membrane in Bacillus subtilis and in other bacterial cells, and co-localizes with its two paralogs, Mbl and MreBH. We show that MreB localizes as dynamic bundles of filaments underneath the cell membrane in Drosophila S2 Schneider cells, which become highly stable when the ATPase motif in MreB is modified. In agreement with ATP-dependent filament formation, the depletion of ATP in the cells lead to rapid dissociation of MreB filaments. Extended induction of MreB resulted in the formation of membrane protrusions, showing that like actin, MreB can exert force against the cell membrane. Mbl also formed membrane associated filaments, while MreBH formed filaments within the cytosol. When co-expressed, MreB, Mbl and MreBH built up mixed filaments underneath the cell membrane. Membrane protein RodZ localized to endosomes in S2 cells, but localized to the cell membrane when co-expressed with Mbl, showing that bacterial MreB/Mbl structures can recruit a protein to the cell membrane. Thus, MreB paralogs form a self-organizing and dynamic filamentous scaffold underneath the membrane that is able to recruit other proteins to the cell surface.

Can we determine the filament chirality by the filament footpoint location or the barb-bearing?

Science.gov (United States)

Hao, Qi; Guo, Yang; Fang, Cheng; Chen, Peng-Fei; Cao, Wen-Da

2016-01-01

We attempt to propose a method for automatically detecting the solar filament chirality and barb bearing. We first introduce the concept of an unweighted undirected graph and adopt the Dijkstra shortest path algorithm to recognize the filament spine. Then, we use the polarity inversion line (PIL) shift method for measuring the polarities on both sides of the filament, and employ the connected components labeling method to identify the barbs and calculate the angle between each barb and the spine to determine the bearing of the barbs, i.e., left or right. We test the automatic detection method with Hα filtergrams from the Big Bear Solar Observatory (BBSO) Hα archive and magnetograms observed with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Four filaments are automatically detected and illustrated to show the results. The barbs in different parts of a filament may have opposite bearings. The filaments in the southern hemisphere (northern hemisphere) mainly have left-bearing (right-bearing) barbs and positive (negative) magnetic helicity, respectively. The tested results demonstrate that our method is efficient and effective in detecting the bearing of filament barbs. It is demonstrated that the conventionally believed one-to-one correspondence between filament chirality and barb bearing is not valid. The correct detection of the filament axis chirality should be done by combining both imaging morphology and magnetic field observations.

Can we determine the filament chirality by the filament footpoint location or the barb-bearing?

International Nuclear Information System (INIS)

Hao, Qi; Guo, Yang; Fang, Cheng; Chen, Peng-Fei; Cao, Wen-Da

2016-01-01

We attempt to propose a method for automatically detecting the solar filament chirality and barb bearing. We first introduce the concept of an unweighted undirected graph and adopt the Dijkstra shortest path algorithm to recognize the filament spine. Then, we use the polarity inversion line (PIL) shift method for measuring the polarities on both sides of the filament, and employ the connected components labeling method to identify the barbs and calculate the angle between each barb and the spine to determine the bearing of the barbs, i.e., left or right. We test the automatic detection method with Hα filtergrams from the Big Bear Solar Observatory (BBSO) Hα archive and magnetograms observed with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Four filaments are automatically detected and illustrated to show the results. The barbs in different parts of a filament may have opposite bearings. The filaments in the southern hemisphere (northern hemisphere) mainly have left-bearing (right-bearing) barbs and positive (negative) magnetic helicity, respectively. The tested results demonstrate that our method is efficient and effective in detecting the bearing of filament barbs. It is demonstrated that the conventionally believed one-to-one correspondence between filament chirality and barb bearing is not valid. The correct detection of the filament axis chirality should be done by combining both imaging morphology and magnetic field observations. (paper)

Helical filaments

Energy Technology Data Exchange (ETDEWEB)

Barbieri, Nicholas; Lim, Khan; Durand, Magali; Baudelet, Matthieu; Richardson, Martin [Townes Laser Institute, CREOL—The College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816 (United States); Hosseinimakarem, Zahra; Johnson, Eric [Micro-Photonics Laboratory – Center for Optical Material Science, Clemson, Anderson, South Carolina 29634 (United States)

2014-06-30

The shaping of laser-induced filamenting plasma channels into helical structures by guiding the process with a non-diffracting beam is demonstrated. This was achieved using a Bessel beam superposition to control the phase of an ultrafast laser beam possessing intensities sufficient to induce Kerr effect driven non-linear self-focusing. Several experimental methods were used to characterize the resulting beams and confirm the observed structures are laser air filaments.

Ultrastructural instability of paired helical filaments from corticobasal degeneration as examined by scanning transmission electron microscopy.

Science.gov (United States)

Ksiezak-Reding, H.; Tracz, E.; Yang, L. S.; Dickson, D. W.; Simon, M.; Wall, J. S.

1996-01-01

Paired helical filaments (PHFs) accumulate in the brains of subjects affected with Alzheimer's disease (AD) and certain other neurodegenerative disorders, including corticobasal degeneration (CBD). Electron microscope studies have shown that PHFs from CBD differ from those of AD by being wider and having a longer periodicity of the helical twist. Moreover, PHFs from CBD have been shown to be primarily composed of two rather than three highly phosphorylated polypeptides of tau (PHF-tau), with these polypeptides expressing no exons 3 and 10. To further explore the relationship between the heterogeneity of PHF-tau and the appearance of abnormal filaments, the ultrastructure and physical parameters such as mass per unit length and dimensions were compared in filaments from CBD and AD using high resolution scanning transmission electron microscopy (STEM). Filament-enriched fractions were isolated as Sarcosyl-insoluble pellets and for STEM studies, samples were freeze-dried without prior fixation or staining. Ultrastructurally, PHFs from CBD were shown to be a heterogeneous population as double- and single-stranded filaments could be identified based on their width and physical mass per unit length expressed in kilodaltons (kd) per nanometer (nm). Less abundant, double-stranded filaments had a maximal width of 29 nm and a mass per unit length of 133 kd/nm, whereas three times more abundant single-stranded filaments were 15 nm wide and bad a mass per unit length of 62 kd/nm. Double-stranded filaments also displayed a distinct axial region of less dense mass, which appeared to divide the PHFs into two protofilament-like strands. Furthermore, these filaments were frequently observed to physically separate along the long axis into two single strands or to break longitudinally. In contrast, PHFs from AD were ultrastructurally stable and uniform both in their width (22 nm) and physical mass per unit length (104 kd/nm). The ultrastructural features indicate that filaments of

Filament poisoning at typical carbon nanotube deposition conditions by hot-filament CVD

CSIR Research Space (South Africa)

Oliphant, CJ

2009-05-01

Full Text Available extensively used for the deposition of various materials, including diamond [1], polymers [2], silicon thin films [3], boron-carbon-nitride layers [4] and carbon nanotubes (CNTs) [5]. The process relies on the catalytic decomposition of precursor gases... (Ho) twice as efficient as a W filament during the deposition of microcrystalline silicon thin films [6]. Reactions between the precursor gases and the heated filament result in changes of the structural properties of the filaments; a process...

Filament wound structure and method

International Nuclear Information System (INIS)

Dritt, W.S.; Gerth, H.L.; Knight, C.E. Jr.; Pardue, R.M.

1977-01-01

A filament wound spherical structure is described comprising a plurality of filament band sets disposed about the surface of a mandrel with each band of each set formed of a continuous filament circumferentially wound about the mandrel a selected number of circuits and with each circuit of filament being wound parallel to and contiguous with an immediate previously wound circuit. Each filament band in each band set is wound at the same helix angle from the axis of revolution of the mandrel and all of the bands of each set are uniformly distributed about the mandrel circumference. The pole-to-equator wall thickness taper associated with each band set, as several contiguous band sets are wound about the mandrel starting at the poles, is accumulative as the band sets are nested to provide a complete filament wound sphere of essentially uniform thickness

Expression of the α2-macroglobulin receptor on human neoplastic fibroblastoid cells

International Nuclear Information System (INIS)

Grofova, M.; Matoska, J.; Bies, J.; Bizik, J.; Vaheri, A.

1995-01-01

The α 2 -macroglobulin membrane-associated receptor ( α 2 MR) has been previously detected on hepatocytes, fibroblast, macrophages, syncytiotrophoblasts and recently on human malignant blood cells of myelomonocytic leukemia. In cells growing in vitro from human germ cell tumors α 2 MR mRNA was detected by Northern blotting. Endocytosis of α 2 MR from culture medium was detected in these cells by indirect immunofluorescence. In cell extracts α 2 MR and its degradation products were detected by immunoblotting. The cells expressing α 2 MR and internalizing α 2 MR were identified as fibroblast both by their morphology and expression of vimentin intermediate filaments. The role and function of α 2 MR receptor in the analyzed neoplastic cells of teratomatous origin is discussed. (author)

Microwave processing of ceramic oxide filaments

Energy Technology Data Exchange (ETDEWEB)

Vogt, G.J.; Katz, J.D. [Los Alamos National Laboratory, NM (United States)

1995-05-01

The objective of the microwave filament processing project is to develop microwave techniques at 2.45 GHZ to manufacture continuous ceramic oxide filaments. Microwave processing uses the volumetric absorption of microwave power in oxide filament tows to drive off process solvents, to burn out organic binders, and to sinter the dried fibers to produce flexible, high-strength ceramic filaments. The technical goal is to advance filament processing technology by microwave heating more rapidly with less energy and at a lower cost than conventional processing, but with the same quality as conventional processing. The manufacturing goal is to collaborate with the 3M Company, a US manufacturer of ceramic oxide filaments, to evaluate the technology using a prototype filament system and to transfer the microwave technology to the 3M Company.

Intermediate monocytes in ANCA vasculitis: increased surface expression of ANCA autoantigens and IL-1β secretion in response to anti-MPO antibodies.

LENUS (Irish Health Repository)

O'Brien, Eóin C

2015-01-01

ANCA vasculitis encompasses several autoimmune conditions characterised by destruction of small vessels, inflammation of the respiratory tract and glomerulonephritis. Most patients harbour autoantibodies to myeloperoxidase (MPO) or proteinase 3 (PR3). Clinical and experimental data suggest that pathogenesis is driven by ANCA-mediated activation of neutrophils and monocytes. We investigated a potential role for distinct monocyte subsets. We found that the relative proportion of intermediate monocytes is increased in patients versus control individuals, and both MPO and PR3 are preferentially expressed on these cells. We demonstrate that MPO and PR3 are expressed independently of each other on monocytes and that PR3 is not associated with CD177. MPO expression correlates with that of Fc receptor CD16 on intermediate monocytes. Monocyte subsets respond differently to antibodies directed against MPO and PR3, with anti-MPO but not anti-PR3 leading to increased IL-1β, IL-6 and IL-8 production. In concordance with the observed higher surface expression of MPO on intermediate monocytes, this subset produces the highest quantity of IL-1β in response to anti-MPO stimulation. These data suggest that monocytes, specifically, the intermediate subset, may play a role in ANCA vasculitis, and also indicate that substantial differences exist between the effect of anti-MPO and anti-PR3 antibodies on these cells.

Solar Features - Prominences and Filaments - Filaments

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Filaments are formed in magnetic loops that hold relatively cool, dense gas suspended above the surface of the Sun (David Hathaway/NASA)

Tungsten Filament Fire

Science.gov (United States)

Ruiz, Michael J.; Perkins, James

2016-01-01

We safely remove the outer glass bulb from an incandescent lamp and burn up the tungsten filament after the glass is removed. This demonstration dramatically illustrates the necessity of a vacuum or inert gas for the environment surrounding the tungsten filament inside the bulb. Our approach has added historical importance since the incandescent…

Epithelial expression of cytokeratins 15 and 19 in vitiligo.

Science.gov (United States)

Saleh, Fatma Y; Awad, Sherif S; Nasif, Ghada A; Halim, Christein

2016-12-01

Cytokeratins (CK) belong to the family of intermediate filament proteins, and among them specific epithelial keratins are considered markers for stem cells activation. This study aims to investigate the expression of CK15 and CK19 as possible stem cell markers in vitiligo during phototherapy. The study was conducted on vitiligo patients receiving narrow-band ultraviolet therapy. Immunohistochemical staining for CK15 and CK19 was carried out, and clinical follow-up continued for 4 weeks. Of 28 patients, CK15 expression was demonstrated in 17 cases (61%) while CK19 expression was demonstrated in 11 cases (39%). Cells expressing positive staining were demonstrated in follicular and interfollicular epithelium. Expression was clearly demonstrated in patients younger than 20 years old, with shorter disease duration, with disease stability, and with normally pigmented hairs. Expression of cytokeratins was significantly correlated to improvement of vitiligo lesions. CK15 and CK19 are expressed in vitiligo during UV repigmentation in the follicular and interfollicular epithelium. This expression of cytokeratins was significantly correlated to improvement and can be considered valuable tool to monitor stem cells stimulation for the sake of the repigmentation process in vitiligo. © 2016 Wiley Periodicals, Inc.

Stability of two-dimensional vorticity filaments

International Nuclear Information System (INIS)

Elhmaidi, D.; Provenzale, A.; Lili, T.; Babiano, A.

2004-01-01

We discuss the results of a numerical study on the stability of two-dimensional vorticity filaments around a circular vortex. We illustrate how the stability of the filaments depends on the balance between the strain associated with the far field of the vortex and the local vorticity of the filament, and we discuss an empirical criterion for filament stability

The Effects of Hsp90α1 Mutations on Myosin Thick Filament Organization.

Science.gov (United States)

He, Qiuxia; Liu, Kechun; Tian, Zhenjun; Du, Shao Jun

2015-01-01

Heat shock protein 90α plays a key role in myosin folding and thick filament assembly in muscle cells. To assess the structure and function of Hsp90α and its potential regulation by post-translational modification, we developed a combined knockdown and rescue assay in zebrafish embryos to systematically analyze the effects of various mutations on Hsp90α function in myosin thick filament organization. DNA constructs expressing the Hsp90α1 mutants with altered putative ATP binding, phosphorylation, acetylation or methylation sites were co-injected with Hsp90α1 specific morpholino into zebrafish embryos. Myosin thick filament organization was analyzed in skeletal muscles of the injected embryos by immunostaining. The results showed that mutating the conserved D90 residue in the Hsp90α1 ATP binding domain abolished its function in thick filament organization. In addition, phosphorylation mimicking mutations of T33D, T33E and T87E compromised Hsp90α1 function in myosin thick filament organization. Similarly, K287Q acetylation mimicking mutation repressed Hsp90α1 function in myosin thick filament organization. In contrast, K206R and K608R hypomethylation mimicking mutations had not effect on Hsp90α1 function in thick filament organization. Given that T33 and T87 are highly conserved residues involved post-translational modification (PTM) in yeast, mouse and human Hsp90 proteins, data from this study could indicate that Hsp90α1 function in myosin thick filament organization is potentially regulated by PTMs involving phosphorylation and acetylation.

Unwinding motion of a twisted active region filament

Energy Technology Data Exchange (ETDEWEB)

Yan, X. L.; Xue, Z. K.; Kong, D. F. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Liu, J. H. [Department of Physics, Shijiazhuang University, Shijiazhuang 050035 (China); Xu, C. L. [Yunnan Normal University, Kunming 650092 (China)

2014-12-10

To better understand the structures of active region filaments and the eruption process, we study an active region filament eruption in active region NOAA 11082 in detail on 2010 June 22. Before the filament eruption, the opposite unidirectional material flows appeared in succession along the spine of the filament. The rising of the filament triggered two B-class flares at the upper part of the filament. As the bright material was injected into the filament from the sites of the flares, the filament exhibited a rapid uplift accompanying the counterclockwise rotation of the filament body. From the expansion of the filament, we can see that the filament consisted of twisted magnetic field lines. The total twist of the filament is at least 5π obtained by using a time slice method. According to the morphology change during the filament eruption, it is found that the active region filament was a twisted flux rope and its unwinding motion was like a solar tornado. We also find that there was a continuous magnetic helicity injection before and during the filament eruption. It is confirmed that magnetic helicity can be transferred from the photosphere to the filament. Using the extrapolated potential fields, the average decay index of the background magnetic fields over the filament is 0.91. Consequently, these findings imply that the mechanism of solar filament eruption could be due to the kink instability and magnetic helicity accumulation.

Filaments and clusters of galaxies

International Nuclear Information System (INIS)

Soltan, A.

1987-01-01

A statistical test to investigate filaments of galaxies is performed. Only particular form of filaments is considered, viz. filaments connecting Abell clusters of galaxies. Relative position of triplets ''cluster - field object - cluster'' is analysed. Though neither cluster sample nor field object sample are homogeneous and complete only peculiar form of selection effects could affect the present statistics. Comparison of observational data with simulations shows that less than 15 per cent of all field galaxies is concentrated in filaments connecting rich clusters. Most of the field objects used in the analysis are not normal galaxies and it is possible that this conclusion is not in conflict with apparent filaments seen in the Lick counts and in some nearby 3D maps of the galaxy distribution. 26 refs., 2 figs. (author)

Evolution of Filament Barbs

OpenAIRE

Liu, Rui; Xu, Yan; Wang, Haimin

2010-01-01

We present a selected few cases in which the sense of chirality of filament barbs changed within as short as hours. We investigate in detail a quiescent filament on 2003 September 10 and 11. Of its four barbs displaying such changes only one overlay a small polarity inversion line inside the EUV filament channel (EFC). No magnetic elements with magnitude above the noise level were detected at the endpoints of all barbs. In particular, a pair of barbs first approached toward and then departed ...

Development of a Novel Green Fluorescent Protein-Based Binding Assay to Study the Association of Plakins with Intermediate Filament Proteins.

Science.gov (United States)

Favre, Bertrand; Begré, Nadja; Bouameur, Jamal-Eddine; Borradori, Luca

2016-01-01

Protein-protein interactions are fundamental for most biological processes, such as the formation of cellular structures and enzymatic complexes or in signaling pathways. The identification and characterization of protein-protein interactions are therefore essential for understanding the mechanisms and regulation of biological systems. The organization and dynamics of the cytoskeleton, as well as its anchorage to specific sites in the plasma membrane and organelles, are regulated by the plakins. These structurally related proteins anchor different cytoskeletal networks to each other and/or to other cellular structures. The association of several plakins with intermediate filaments (IFs) is critical for maintenance of the cytoarchitecture. Pathogenic mutations in the genes encoding different plakins can lead to dramatic manifestations, occurring principally in the skin, striated muscle, and/or nervous system, due to cytoskeletal disorganization resulting in abnormal cell fragility. Nevertheless, it is still unclear how plakins bind to IFs, although some general rules are slowly emerging. We here describe in detail a recently developed protein-protein fluorescence binding assay, based on the production of recombinant proteins tagged with green fluorescent protein (GFP) and their use as fluid-phase fluorescent ligands on immobilized IF proteins. Using this method, we have been able to assess the ability of C-terminal regions of GFP-tagged plakin proteins to bind to distinct IF proteins and IF domains. This simple and sensitive technique, which is expected to facilitate further studies in this area, can also be potentially employed for any kind of protein-protein interaction studies. © 2016 Elsevier Inc. All rights reserved.

Myosin binding protein-C activates thin filaments and inhibits thick filaments in heart muscle cells.

Science.gov (United States)

Kampourakis, Thomas; Yan, Ziqian; Gautel, Mathias; Sun, Yin-Biao; Irving, Malcolm

2014-12-30

Myosin binding protein-C (MyBP-C) is a key regulatory protein in heart muscle, and mutations in the MYBPC3 gene are frequently associated with cardiomyopathy. However, the mechanism of action of MyBP-C remains poorly understood, and both activating and inhibitory effects of MyBP-C on contractility have been reported. To clarify the function of the regulatory N-terminal domains of MyBP-C, we determined their effects on the structure of thick (myosin-containing) and thin (actin-containing) filaments in intact sarcomeres of heart muscle. We used fluorescent probes on troponin C in the thin filaments and on myosin regulatory light chain in the thick filaments to monitor structural changes associated with activation of demembranated trabeculae from rat ventricle by the C1mC2 region of rat MyBP-C. C1mC2 induced larger structural changes in thin filaments than calcium activation, and these were still present when active force was blocked with blebbistatin, showing that C1mC2 directly activates the thin filaments. In contrast, structural changes in thick filaments induced by C1mC2 were smaller than those associated with calcium activation and were abolished or reversed by blebbistatin. Low concentrations of C1mC2 did not affect resting force but increased calcium sensitivity and reduced cooperativity of force and structural changes in both thin and thick filaments. These results show that the N-terminal region of MyBP-C stabilizes the ON state of thin filaments and the OFF state of thick filaments and lead to a novel hypothesis for the physiological role of MyBP-C in the regulation of cardiac contractility.

Determining advection mechanism of plasma filaments in the scrape-off layer of MAST

International Nuclear Information System (INIS)

Higgins, D; Hnat, B; Kirk, A; Tamain, P; Ben Ayed, N

2012-01-01

The scrape-off layer (SOL) of fusion devices is typically composed of filamentary structures that propagate with a high radial velocity away from the bulk plasma. When radial and parallel transport times are comparable, these coherent structures constitute an intermittent heat and particle flux which can reach the material wall; in time causing wear to plasma facing components. Qualitative models predict that the parallel currents, driven by the divertor sheath, have a direct impact on this radial velocity. In this work, the predictions for radial velocity of plasma filaments in the SOL from models are tested against data from the MAST tokamak and simulation. We apply a statistical method of window averaging to MAST Langmuir probe data in order to examine the scaling of the radial velocity of filaments with the plasma density inside the filaments. Our analysis strongly suggests that the radial dynamics emerge from the competition of multiple mechanisms and not from a single process. At intermediate distances from the bulk plasma, a new model proposed here, in which the parallel current depends on a constant target density appears to be the most relevant for the MAST plasma. This is confirmed using a TOKAM2D simulation with a modified parallel current term.

Interaction of in-phase and out-of-phase flexible filament in fish schooling

Science.gov (United States)

Ud Din, Emad; Sung, Hyung

2011-11-01

Fish schooling is not merely a social behavior; schooling improves the efficiency of movement within the fluid environment. Inspired by the schooling from a hydrodynamic perspective, a group of aquatic animals is modeled as a collection of individuals arranged in a combination of tandem and side-by-side (diamond) formation. The downstream bodies are strongly influenced by the vortices shed by the upstream body shown by vortex-vortex and vortex-body interactions. Trailing fish takes advantage of this flow pattern for energy economy. To investigate the interactions between flexible bodies and vortices, in the present study three flexible flags in viscous flow are solved by numerical simulation using an improved version of the immersed boundary method for in-phase and out-of-phase filaments. The drag coefficient of the downstream filaments drops even below the value of a single flag. Such drag variations are influenced by the interactions between vortices shed by the upstream flexible body and vortices surrounding the downstream filaments. Interaction of the flexible flags is investigated as a function of the gap distance between flags and different bending coefficients, for in-phase and out-of-phase cases at intermediate Reynolds numbers. This study was supported by the Creative Research Initiatives of NRF/MEST (No. 2011-0000423) of Korea.

Electron emitting filaments for electron discharge devices

International Nuclear Information System (INIS)

Leung, K.N.; Pincosy, P.A.; Ehlers, K.W.

1988-01-01

This patent describes an electron emitting device for use in an electron discharge system. It comprises: a filament having a pair of terminal ends, electrical supply means for supplying electrical power to the terminal ends of the filament for directly heating the filament by the passage of an electrical current along the filament between the terminal ends, the filament being substantially tapered in cross section continuously in one direction from one of its pair of terminal ends to another of its pair of terminal ends to achieve uniform heating of the filament along the length thereof by compensating for the nonuniform current along the filament due to the emission of electrons therefrom

Analysis of a filament stretching rheometer

DEFF Research Database (Denmark)

Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

1996-01-01

A finite element analysis of the stretching filament rheometer of Tirtaadmadja and Sridhar (1993) is presenetd. Simulations of the stretching of a filament of the polymet test solution, fluid A, between two plates are shown.......A finite element analysis of the stretching filament rheometer of Tirtaadmadja and Sridhar (1993) is presenetd. Simulations of the stretching of a filament of the polymet test solution, fluid A, between two plates are shown....

Interplay between Solo and keratin filaments is crucial for mechanical force-induced stress fiber reinforcement.

Science.gov (United States)

Fujiwara, Sachiko; Ohashi, Kazumasa; Mashiko, Toshiya; Kondo, Hiroshi; Mizuno, Kensaku

2016-03-15

Mechanical force-induced cytoskeletal reorganization is essential for cell and tissue remodeling and homeostasis; however, the underlying cellular mechanisms remain elusive. Solo (ARHGEF40) is a RhoA-targeting guanine nucleotide exchange factor (GEF) involved in cyclical stretch-induced human endothelial cell reorientation and convergent extension cell movement in zebrafish gastrula. In this study, we show that Solo binds to keratin-8/keratin-18 (K8/K18) intermediate filaments through multiple sites. Solo overexpression promotes the formation of thick actin stress fibers and keratin bundles, whereas knockdown of Solo, expression of a GEF-inactive mutant of Solo, or inhibition of ROCK suppresses stress fiber formation and leads to disorganized keratin networks, indicating that the Solo-RhoA-ROCK pathway serves to precisely organize keratin networks, as well as to promote stress fibers. Of importance, knockdown of Solo or K18 or overexpression of GEF-inactive or deletion mutants of Solo suppresses tensile force-induced stress fiber reinforcement. Furthermore, knockdown of Solo or K18 suppresses tensile force-induced RhoA activation. These results strongly suggest that the interplay between Solo and K8/K18 filaments plays a crucial role in tensile force-induced RhoA activation and consequent actin cytoskeletal reinforcement. © 2016 Fujiwara et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Proteomics of Filamentous Fungi

NARCIS (Netherlands)

Passel, van M.W.J.; Schaap, P.J.; Graaff, de L.H.

2013-01-01

Filamentous fungi, such as Aspergillus niger and Aspergillus oryzae traditionally have had an important role in providing enzymes and enzyme cocktails that are used in food industry. In recent years the genome sequences of many filamentous fungi have become available. This combined with

The Mysterious Case of the Missing Filaments

Science.gov (United States)

Alden, C. R.

2016-12-01

Coronal Mass Ejections, or CMEs, are large solar eruptions that can have major debilitating impacts on society. Typically, these eruptions have the three following key structures: the leading edge, the empty chamber known as the cavity, and the filament which often is the brightest part of the CME. When we can see all three structures clearly with a coronagraph, it is called a classic three-part CME, also referred to as a 'lightbulb' CME. According to current knowledge, when a CME erupts, a filament should also erupt or lift off the Sun in order to have the bright center within the CME. However, we do not always see a filament erupt at the surface, and yet we still get a 'filament' within the coronagraph CME. To better understand what might be occurring with these missing filaments, we looked at three-part CMEs using the SOHO LASCO CME Catalog and filaments from the SDO AIA Filament Catalog in order to create a list of 50 CMEs without a listed filament erupting at the surface. For those CMEs without filaments in the list we closely inspected the AIA images for evidence of filament eruption. To ensure that there were no filaments past the limb of the Sun, we used data from the STEREO-A and STEREO-B spacecraft's to look at the Sun from other angles. We have found numerous events where no filament erupts from the surface, but we still see the classic three-part CME. We believe this may be due to an optical illusion occurring from the twisting of the flux rope.

Soliton on thin vortex filament

International Nuclear Information System (INIS)

Konno, Kimiaki; Mituhashi, Masahiko; Ichikawa, Y.H.

1990-12-01

Showing that one of the equations found by Wadati, Konno and Ichikawa is equivalent to the equation of motion of a thin vortex filament, we investigate solitons on the vortex filament. N vortex soliton solution is given in terms of the inverse scattering method. We examine two soliton collision processes on the filament. Our analysis provides the theoretical foundation of two soliton collision processes observed numerically by Aref and Flinchem. (author)

EST Table: AV404130 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available n (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Tribolium castaneum] 10/08/28 53...78 aa gnl|Amel|GB30360-PB 10/09/10 54 %/199 aa gi|189241063|ref|XP_967018.2| PREDICTED: similar to restin (Reed-Steinberg cell-expres...sed intermediate filament-associated protein) [Tribolium castaneum] FS906662 pg-- ... ...AV404130 pg--0509 10/09/28 54 %/199 aa ref|XP_967018.2| PREDICTED: similar to resti

EST Table: FY010414 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available in (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Tribolium castaneum] 11/11/04 5...149 aa gnl|Amel|GB30360-PB 11/11/04 52 %/187 aa gi|189241063|ref|XP_967018.2| PREDICTED: similar to restin (Reed-Steinberg cell-expre...ssed intermediate filament-associated protein) [Tribolium castaneum] FS906662 bmov ... ...FY010414 bmov30c17 11/11/04 52 %/187 aa ref|XP_967018.2| PREDICTED: similar to rest

EST Table: BP183486 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available n (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Tribolium castaneum] 10/08/29 56...43 aa gnl|Amel|GB30360-PB 10/09/10 54 %/174 aa gi|189241063|ref|XP_967018.2| PREDICTED: similar to restin (Reed-Steinberg cell-expres...sed intermediate filament-associated protein) [Tribolium castaneum] FS906662 NRPG ... ...BP183486 NRPG1970 10/09/28 54 %/174 aa ref|XP_967018.2| PREDICTED: similar to resti

Striation and convection in penumbral filaments

NARCIS (Netherlands)

Spruit, H.C.; Scharmer, G.B.; Löfdahl, M.G.

2010-01-01

Observations with the 1-m Swedish Solar Telescope of the flows seen in penumbral filaments are presented. Time sequences of bright filaments show overturning motions strikingly similar to those seen along the walls of small isolated structures in the active regions. The filaments show outward

Characterization of cytoskeletal and junctional proteins expressed by cells cultured from human arachnoid granulation tissue

Directory of Open Access Journals (Sweden)

Mehta Bhavya C

2005-10-01

Full Text Available Abstract Background The arachnoid granulations (AGs are projections of the arachnoid membrane into the dural venous sinuses. They function, along with the extracranial lymphatics, to circulate the cerebrospinal fluid (CSF to the systemic venous circulation. Disruption of normal CSF dynamics may result in increased intracranial pressures causing many problems including headaches and visual loss, as in idiopathic intracranial hypertension and hydrocephalus. To study the role of AGs in CSF egress, we have grown cells from human AG tissue in vitro and have characterized their expression of those cytoskeletal and junctional proteins that may function in the regulation of CSF outflow. Methods Human AG tissue was obtained at autopsy, and explanted to cell culture dishes coated with fibronectin. Typically, cells migrated from the explanted tissue after 7–10 days in vitro. Second or third passage cells were seeded onto fibronectin-coated coverslips at confluent densities and grown to confluency for 7–10 days. Arachnoidal cells were tested using immunocytochemical methods for the expression of several common cytoskeletal and junctional proteins. Second and third passage cultures were also labeled with the common endothelial markers CD-31 or VE-cadherin (CD144 and their expression was quantified using flow cytometry analysis. Results Confluent cultures of arachnoidal cells expressed the intermediate filament protein vimentin. Cytokeratin intermediate filaments were expressed variably in a subpopulation of cells. The cultures also expressed the junctional proteins connexin43, desmoplakin 1 and 2, E-cadherin, and zonula occludens-1. Flow cytometry analysis indicated that second and third passage cultures failed to express the endothelial cell markers CD31 or VE-cadherin in significant quantities, thereby showing that these cultures did not consist of endothelial cells from the venous sinus wall. Conclusion To our knowledge, this is the first report of

Boolean gates on actin filaments

International Nuclear Information System (INIS)

Siccardi, Stefano; Tuszynski, Jack A.; Adamatzky, Andrew

2016-01-01

Actin is a globular protein which forms long polar filaments in the eukaryotic cytoskeleton. Actin networks play a key role in cell mechanics and cell motility. They have also been implicated in information transmission and processing, memory and learning in neuronal cells. The actin filaments have been shown to support propagation of voltage pulses. Here we apply a coupled nonlinear transmission line model of actin filaments to study interactions between voltage pulses. To represent digital information we assign a logical TRUTH value to the presence of a voltage pulse in a given location of the actin filament, and FALSE to the pulse's absence, so that information flows along the filament with pulse transmission. When two pulses, representing Boolean values of input variables, interact, then they can facilitate or inhibit further propagation of each other. We explore this phenomenon to construct Boolean logical gates and a one-bit half-adder with interacting voltage pulses. We discuss implications of these findings on cellular process and technological applications. - Highlights: • We simulate interaction between voltage pulses using on actin filaments. • We use a coupled nonlinear transmission line model. • We design Boolean logical gates via interactions between the voltage pulses. • We construct one-bit half-adder with interacting voltage pulses.

Boolean gates on actin filaments

Energy Technology Data Exchange (ETDEWEB)

Siccardi, Stefano, E-mail: ssiccardi@2ssas.it [The Unconventional Computing Centre, University of the West of England, Bristol (United Kingdom); Tuszynski, Jack A., E-mail: jackt@ualberta.ca [Department of Oncology, University of Alberta, Edmonton, Alberta (Canada); Adamatzky, Andrew, E-mail: andrew.adamatzky@uwe.ac.uk [The Unconventional Computing Centre, University of the West of England, Bristol (United Kingdom)

2016-01-08

Actin is a globular protein which forms long polar filaments in the eukaryotic cytoskeleton. Actin networks play a key role in cell mechanics and cell motility. They have also been implicated in information transmission and processing, memory and learning in neuronal cells. The actin filaments have been shown to support propagation of voltage pulses. Here we apply a coupled nonlinear transmission line model of actin filaments to study interactions between voltage pulses. To represent digital information we assign a logical TRUTH value to the presence of a voltage pulse in a given location of the actin filament, and FALSE to the pulse's absence, so that information flows along the filament with pulse transmission. When two pulses, representing Boolean values of input variables, interact, then they can facilitate or inhibit further propagation of each other. We explore this phenomenon to construct Boolean logical gates and a one-bit half-adder with interacting voltage pulses. We discuss implications of these findings on cellular process and technological applications. - Highlights: • We simulate interaction between voltage pulses using on actin filaments. • We use a coupled nonlinear transmission line model. • We design Boolean logical gates via interactions between the voltage pulses. • We construct one-bit half-adder with interacting voltage pulses.

Translation elongation factor EF-Tu modulates filament formation of actin-like MreB protein in vitro.

Science.gov (United States)

Defeu Soufo, Hervé Joël; Reimold, Christian; Breddermann, Hannes; Mannherz, Hans G; Graumann, Peter L

2015-04-24

EF-Tu has been shown to interact with actin-like protein MreB and to affect its localization in Escherichia coli and in Bacillus subtilis cells. We have purified YFP-MreB in an active form, which forms filaments on glass slides in vitro and was active in dynamic light-scattering assays, polymerizing in milliseconds after addition of magnesium. Purified EF-Tu enhanced the amount of MreB filaments, as seen by sedimentation assays, the speed of filament formation and the length of MreB filaments in vitro. EF-Tu had the strongest impact on MreB filaments in a 1:1 ratio, and EF-Tu co-sedimented with MreB filaments, revealing a stoichiometric interaction between both proteins. This was supported by cross-linking assays where 1:1 species were well detectable. When expressed in E. coli cells, B. subtilis MreB formed filaments and induced the formation of co-localizing B. subtilis EF-Tu structures, indicating that MreB can direct the positioning of EF-Tu structures in a heterologous cell system. Fluorescence recovery after photobleaching analysis showed that MreB filaments have a higher turnover in B. subtilis cells than in E. coli cells, indicating different filament kinetics in homologous or heterologous cell systems. The data show that MreB can direct the localization of EF-Tu in vivo, which in turn positively affects the formation and dynamics of MreB filaments. Thus, EF-Tu is a modulator of the activity of a bacterial actin-like protein. Copyright © 2015. Published by Elsevier Ltd.

Solar filament material oscillations and drainage before eruption

International Nuclear Information System (INIS)

Bi, Yi; Jiang, Yunchun; Yang, Jiayan; Hong, Junchao; Li, Haidong; Yang, Dan; Yang, Bo

2014-01-01

Both large-amplitude longitudinal (LAL) oscillations and material drainage in a solar filament are associated with the flow of material along the filament axis, often followed by an eruption. However, the relationship between these two motions and a subsequent eruption event is poorly understood. We analyze a filament eruption using EUV imaging data captured by the Atmospheric Imaging Array on board the Solar Dynamics Observatory and the Hα images from the Global Oscillation Network Group. Hours before the eruption, the filament was activated, with one of its legs undergoing a slow rising motion. The asymmetric activation inclined the filament relative to the solar surface. After the active phase, LAL oscillations were observed in the inclined filament. The oscillation period increased slightly over time, which may suggest that the magnetic fields supporting the filament evolve to be flatter during the slow rising phase. After the oscillations, a significant amount of filament material was drained toward one filament endpoint, followed immediately by the violent eruption of the filament. The material drainage may further support the change in magnetic topology prior to the eruption. Moreover, we suggest that the filament material drainage could play a role in the transition from a slow to a fast rise of the erupting filament.

Dynamic Filament Formation by a Divergent Bacterial Actin-Like ParM Protein.

Directory of Open Access Journals (Sweden)

Anthony J Brzoska

Full Text Available Actin-like proteins (Alps are a diverse family of proteins whose genes are abundant in the chromosomes and mobile genetic elements of many bacteria. The low-copy-number staphylococcal multiresistance plasmid pSK41 encodes ParM, an Alp involved in efficient plasmid partitioning. pSK41 ParM has previously been shown to form filaments in vitro that are structurally dissimilar to those formed by other bacterial Alps. The mechanistic implications of these differences are not known. In order to gain insights into the properties and behavior of the pSK41 ParM Alp in vivo, we reconstituted the parMRC system in the ectopic rod-shaped host, E. coli, which is larger and more genetically amenable than the native host, Staphylococcus aureus. Fluorescence microscopy showed a functional fusion protein, ParM-YFP, formed straight filaments in vivo when expressed in isolation. Strikingly, however, in the presence of ParR and parC, ParM-YFP adopted a dramatically different structure, instead forming axial curved filaments. Time-lapse imaging and selective photobleaching experiments revealed that, in the presence of all components of the parMRC system, ParM-YFP filaments were dynamic in nature. Finally, molecular dissection of the parMRC operon revealed that all components of the system are essential for the generation of dynamic filaments.

Prediction of Solar Eruptions Using Filament Metadata

Science.gov (United States)

Aggarwal, Ashna; Schanche, Nicole; Reeves, Katharine K.; Kempton, Dustin; Angryk, Rafal

2018-05-01

We perform a statistical analysis of erupting and non-erupting solar filaments to determine the properties related to the eruption potential. In order to perform this study, we correlate filament eruptions documented in the Heliophysics Event Knowledgebase (HEK) with HEK filaments that have been grouped together using a spatiotemporal tracking algorithm. The HEK provides metadata about each filament instance, including values for length, area, tilt, and chirality. We add additional metadata properties such as the distance from the nearest active region and the magnetic field decay index. We compare trends in the metadata from erupting and non-erupting filament tracks to discover which properties present signs of an eruption. We find that a change in filament length over time is the most important factor in discriminating between erupting and non-erupting filament tracks, with erupting tracks being more likely to have decreasing length. We attempt to find an ensemble of predictive filament metadata using a Random Forest Classifier approach, but find the probability of correctly predicting an eruption with the current metadata is only slightly better than chance.

NONLINEAR FORCE-FREE FIELD EXTRAPOLATION OF A CORONAL MAGNETIC FLUX ROPE SUPPORTING A LARGE-SCALE SOLAR FILAMENT FROM A PHOTOSPHERIC VECTOR MAGNETOGRAM

Energy Technology Data Exchange (ETDEWEB)

Jiang, Chaowei; Wu, S. T.; Hu, Qiang [Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Feng, Xueshang, E-mail: cwjiang@spaceweather.ac.cn, E-mail: wus@uah.edu, E-mail: qh0001@uah.edu, E-mail: fengx@spaceweather.ac.cn [SIGMA Weather Group, State Key Laboratory for Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China)

2014-05-10

Solar filaments are commonly thought to be supported in magnetic dips, in particular, in those of magnetic flux ropes (FRs). In this Letter, based on the observed photospheric vector magnetogram, we implement a nonlinear force-free field (NLFFF) extrapolation of a coronal magnetic FR that supports a large-scale intermediate filament between an active region and a weak polarity region. This result is a first, in the sense that current NLFFF extrapolations including the presence of FRs are limited to relatively small-scale filaments that are close to sunspots and along main polarity inversion lines (PILs) with strong transverse field and magnetic shear, and the existence of an FR is usually predictable. In contrast, the present filament lies along the weak-field region (photospheric field strength ≲ 100 G), where the PIL is very fragmented due to small parasitic polarities on both sides of the PIL and the transverse field has a low signal-to-noise ratio. Thus, extrapolating a large-scale FR in such a case represents a far more difficult challenge. We demonstrate that our CESE-MHD-NLFFF code is sufficient for the challenge. The numerically reproduced magnetic dips of the extrapolated FR match observations of the filament and its barbs very well, which strongly supports the FR-dip model for filaments. The filament is stably sustained because the FR is weakly twisted and strongly confined by the overlying closed arcades.

Temperature distributions of a conductively heated filament

International Nuclear Information System (INIS)

Tamura, Koji; Ohba, Hironori; Shibata, Takemasa

1999-07-01

Temperature distributions of a heated filament were measured. A W-Re(5%) filament (0.25 mm in diameter, 24.7 mm in length) was conductively heated by currents between 5A and 7A with a DC power supply, and the surface of the filament was imaged with a charge coupled device (CCD) camera through a monochromatic filter. The spectral radiation intensity at the filament center region was almost uniform. Since the temperature distribution was also uniform and the energy loss by thermal conduction was negligible, temperature in this region was determined from the energy balance between applied power and radiation loss. Temperature distribution of the filament was determined based on the Planck's law of radiation from the spectral radiation intensity ratio of the filament surface using obtained temperature as a reference. It was found that temperature distribution of a filament was easily measured by this method. (author)

Measuring Filament Orientation: A New Quantitative, Local Approach

Energy Technology Data Exchange (ETDEWEB)

Green, C.-E.; Cunningham, M. R.; Jones, P. A. [School of Physics, University of New South Wales, Sydney, NSW, 2052 (Australia); Dawson, J. R. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia); Novak, G. [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Fissel, L. M. [National Radio Astronomy Observatory (NRAO), 520 Edgemont Road, Charlottesville, VA, 22903 (United States)

2017-09-01

The relative orientation between filamentary structures in molecular clouds and the ambient magnetic field provides insight into filament formation and stability. To calculate the relative orientation, a measurement of filament orientation is first required. We propose a new method to calculate the orientation of the one-pixel-wide filament skeleton that is output by filament identification algorithms such as filfinder. We derive the local filament orientation from the direction of the intensity gradient in the skeleton image using the Sobel filter and a few simple post-processing steps. We call this the “Sobel-gradient method.” The resulting filament orientation map can be compared quantitatively on a local scale with the magnetic field orientation map to then find the relative orientation of the filament with respect to the magnetic field at each point along the filament. It can also be used for constructing radial profiles for filament width fitting. The proposed method facilitates automation in analyses of filament skeletons, which is imperative in this era of “big data.”.

Measuring Filament Orientation: A New Quantitative, Local Approach

Science.gov (United States)

Green, C.-E.; Dawson, J. R.; Cunningham, M. R.; Jones, P. A.; Novak, G.; Fissel, L. M.

2017-09-01

The relative orientation between filamentary structures in molecular clouds and the ambient magnetic field provides insight into filament formation and stability. To calculate the relative orientation, a measurement of filament orientation is first required. We propose a new method to calculate the orientation of the one-pixel-wide filament skeleton that is output by filament identification algorithms such as filfinder. We derive the local filament orientation from the direction of the intensity gradient in the skeleton image using the Sobel filter and a few simple post-processing steps. We call this the “Sobel-gradient method.” The resulting filament orientation map can be compared quantitatively on a local scale with the magnetic field orientation map to then find the relative orientation of the filament with respect to the magnetic field at each point along the filament. It can also be used for constructing radial profiles for filament width fitting. The proposed method facilitates automation in analyses of filament skeletons, which is imperative in this era of “big data.”

Measuring Filament Orientation: A New Quantitative, Local Approach

International Nuclear Information System (INIS)

Green, C.-E.; Cunningham, M. R.; Jones, P. A.; Dawson, J. R.; Novak, G.; Fissel, L. M.

2017-01-01

The relative orientation between filamentary structures in molecular clouds and the ambient magnetic field provides insight into filament formation and stability. To calculate the relative orientation, a measurement of filament orientation is first required. We propose a new method to calculate the orientation of the one-pixel-wide filament skeleton that is output by filament identification algorithms such as filfinder. We derive the local filament orientation from the direction of the intensity gradient in the skeleton image using the Sobel filter and a few simple post-processing steps. We call this the “Sobel-gradient method.” The resulting filament orientation map can be compared quantitatively on a local scale with the magnetic field orientation map to then find the relative orientation of the filament with respect to the magnetic field at each point along the filament. It can also be used for constructing radial profiles for filament width fitting. The proposed method facilitates automation in analyses of filament skeletons, which is imperative in this era of “big data.”

Solar Features - Prominences and Filaments

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Prominences and filaments are two manifestations of the same phenomenon. Both prominences and filaments are features formed above the chromosphere by cool dense...

Dynamics and mechanics of motor-filament systems

Science.gov (United States)

Kruse, K.; Jülicher, F.

2006-08-01

Motivated by the cytoskeleton of eukaryotic cells, we develop a general framework for describing the large-scale dynamics of an active filament network. In the cytoskeleton, active cross-links are formed by motor proteins that are able to induce relative motion between filaments. Starting from pair-wise interactions of filaments via such active processes, our framework is based on momentum conservation and an analysis of the momentum flux. This allows us to calculate the stresses in the filament network generated by the action of motor proteins. We derive effective theories for the filament dynamics which can be related to continuum theories of active polar gels. As an example, we discuss the stability of homogenous isotropic filament distributions in two spatial dimensions.

Analytical Core Mass Function (CMF) from Filaments: Under Which Circumstances Can Filament Fragmentation Reproduce the CMF?

Energy Technology Data Exchange (ETDEWEB)

Lee, Yueh-Ning; Hennebelle, Patrick [IRFU, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette (France); Chabrier, Gilles, E-mail: yueh-ning.lee@cea.fr [École normale supérieure de Lyon, CRAL, UMR CNRS 5574, Université de Lyon, F-69364 Lyon Cedex 07 (France)

2017-10-01

Observations suggest that star formation in filamentary molecular clouds occurs in a two-step process, with the formation of filaments preceding that of prestellar cores and stars. Here, we apply the gravoturbulent fragmentation theory of Hennebelle and Chabrier to a filamentary environment, taking into account magnetic support. We discuss the induced geometrical effect on the cores, with a transition from 3D geometry at small scales to 1D at large ones. The model predicts the fragmentation behavior of a filament for a given mass per unit length (MpL) and level of magnetization. This core mass function (CMF) for individual filaments is then convolved with the distribution of filaments to obtain the final system CMF. The model yields two major results. (i) The filamentary geometry naturally induces a hierarchical fragmentation process, first into groups of cores, separated by a length equal to a few filament Jeans lengths, i.e., a few times the filament width. These groups then fragment into individual cores. (ii) Non-magnetized filaments with high MpL are found to fragment excessively, at odds with observations. This is resolved by taking into account the magnetic field (treated simply as additional pressure support). The present theory suggests two complementary modes of star formation: although small (spherical or filamentary) structures will collapse directly into prestellar cores, according to the standard Hennebelle–Chabrier theory, the large (filamentary) ones, the dominant population according to observations, will follow the aforedescribed two-step process.

Automatic Detect and Trace of Solar Filaments

Science.gov (United States)

Fang, Cheng; Chen, P. F.; Tang, Yu-hua; Hao, Qi; Guo, Yang

We developed a series of methods to automatically detect and trace solar filaments in solar Hα images. The programs are able to not only recognize filaments and determine their properties, such as the position, the area and other relevant parameters, but also to trace the daily evolution of the filaments. For solar full disk Hα images, the method consists of three parts: first, preprocessing is applied to correct the original images; second, the Canny edge-detection method is used to detect the filaments; third, filament properties are recognized through the morphological operators. For each Hα filament and its barb features, we introduced the unweighted undirected graph concept and adopted Dijkstra shortest-path algorithm to recognize the filament spine; then, using polarity inversion line shift method for measuring the polarities in both sides of the filament to determine the filament axis chirality; finally, employing connected components labeling method to identify the barbs and calculating the angle between each barb and spine to indicate the barb chirality. Our algorithms are applied to the observations from varied observatories, including the Optical & Near Infrared Solar Eruption Tracer (ONSET) in Nanjing University, Mauna Loa Solar Observatory (MLSO) and Big Bear Solar Observatory (BBSO). The programs are demonstrated to be effective and efficient. We used our method to automatically process and analyze 3470 images obtained by MLSO from January 1998 to December 2009, and a butterfly diagram of filaments is obtained. It shows that the latitudinal migration of solar filaments has three trends in the Solar Cycle 23: The drift velocity was fast from 1998 to the solar maximum; after the solar maximum, it became relatively slow and after 2006, the migration became divergent, signifying the solar minimum. About 60% filaments with the latitudes larger than 50 degree migrate towards the Polar Regions with relatively high velocities, and the latitudinal migrating

High-resolution Observations of Sympathetic Filament Eruptions by NVST

Energy Technology Data Exchange (ETDEWEB)

Li, Shangwei; Su, Yingna; Zhou, Tuanhui; Ji, Haisheng [Key Laboratory for Dark Matter and Space Science, Purple Mountain Observatory, CAS, Nanjing 210008 (China); Van Ballegooijen, Adriaan [5001 Riverwood Avenue, Sarasota, FL 34231 (United States); Sun, Xudong, E-mail: ynsu@pmo.ac.cn [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States)

2017-07-20

We investigate two sympathetic filament eruptions observed by the New Vacuum Solar Telescope on 2015 October 15. The full picture of the eruptions is obtained from the corresponding Solar Dynamics Observatory ( SDO )/Atmospheric Imaging Assembly (AIA) observations. The two filaments start from active region NOAA 12434 in the north and end in one large quiescent filament channel in the south. The left filament erupts first, followed by the right filament eruption about 10 minutes later. Clear twist structure and rotating motion are observed in both filaments during the eruption. Both eruptions failed, since the filaments first rise up, then flow toward the south and merge into the southern large quiescent filament. We also observe repeated activations of mini filaments below the right filament after its eruption. Using magnetic field models constructed based on SDO /HMI magnetograms via the flux rope insertion method, we find that the left filament eruption is likely to be triggered by kink instability, while the weakening of overlying magnetic fields due to magnetic reconnection at an X-point between the two filament systems might play an important role in the onset of the right filament eruption.

Arsenite induced oxidative damage in mouse liver is associated with increased cytokeratin 18 expression

Energy Technology Data Exchange (ETDEWEB)

Gonsebatt, M.E. [UNAM, Ciudad Universitaria, Dept. Medicina Genomica y Toxicologia Ambiental, Instituto de Investigaciones Biomedicas, Mexico (Mexico); Razo, L.M. del; Sanchez-Pena, L.C. [Seccion de Toxicologia, CINVESTAV, Mexico (Mexico); Cerbon, M.A. [Facultad de Quimica, UNAM, Departamento de Biologia, Mexico (Mexico); Zuniga, O.; Ramirez, P. [Facultad de Estudios Superiores Cuautitlan, UNAM, Laboratorio de Toxicologia Celular, Coordinacion General de Estudios de Posgrado e Investigacion, Cuautitlan Izcalli, Estado de Mexico (Mexico)

2007-09-15

Cytokeratins (CK) constitute a family of cytoskeletal intermediate filament proteins that are typically expressed in epithelial cells. An abnormal structure and function are effects that are clearly related to liver diseases as non-alcoholic steatohepatitis, cirrhosis and hepatocellular carcinoma. We have previously observed that sodium arsenite (SA) induced the synthesis of CK18 protein and promotes a dose-related disruption of cytoplasmic CK18 filaments in a human hepatic cell line. Both abnormal gene expression and disturbance of structural organization are toxic effects that are likely to cause liver disease by interfering with normal hepatocyte function. To investigate if a disruption in the CK18 expression pattern is associated with arsenite liver damage, we investigated CK18 mRNA and protein levels in liver slices treated with low levels of SA. Organotypic cultures were incubated with 0.01, 1 and 10 {mu}M of SA in the absence and presence of N-acetyl cysteine (NAC). Cell viability and inorganic arsenic metabolism were determined. Increased expression of CK18 was observed after exposure to SA. The addition of NAC impeded the oxidative effects of SA exposure, decreasing the production of thiobarbituric acid-reactive substances and significantly diminishing the up regulation of CK18 mRNA and protein. Liver arsenic levels correlated with increased levels of mRNA. Mice treated with intragastric single doses of 2.5 and 5 mg/kg of SA showed an increased expression of CK18. Results suggest that CK18 expression may be a sensible early biomarker of oxidative stress and damage induced by arsenite in vitro and in vivo. Then, during SA exposure, altered CK expression may compromise liver function. (orig.)

A semi-flexible model prediction for the polymerization force exerted by a living F-actin filament on a fixed wall

Science.gov (United States)

Pierleoni, Carlo; Ciccotti, Giovanni; Ryckaert, Jean-Paul

2015-10-01

We consider a single living semi-flexible filament with persistence length ℓp in chemical equilibrium with a solution of free monomers at fixed monomer chemical potential μ1 and fixed temperature T. While one end of the filament is chemically active with single monomer (de)polymerization steps, the other end is grafted normally to a rigid wall to mimic a rigid network from which the filament under consideration emerges. A second rigid wall, parallel to the grafting wall, is fixed at distance L chain model with step size d and persistence length ℓp, hitting a hard wall. Explicit properties require the computation of the mean force f ¯ i ( L ) exerted by the wall at L and associated potential f ¯ i ( L ) = - d W i ( L ) / d L on a filament of fixed size i. By original Monte-Carlo calculations for few filament lengths in a wide range of compression, we justify the use of the weak bending universal expressions of Gholami et al. [Phys. Rev. E 74, 041803 (2006)] over the whole non-escaping filament regime. For a filament of size i with contour length Lc = (i - 1) d, this universal form is rapidly growing from zero (non-compression state) to the buckling value f b ( L c , ℓ p ) = /π 2 k B T ℓ p 4 Lc 2 over a compression range much narrower than the size d of a monomer. Employing this universal form for living filaments, we find that the average force exerted by a living filament on a wall at distance L is in practice L independent and very close to the value of the stalling force Fs H = ( k B T / d ) ln ( ρ ˆ 1 ) predicted by Hill, this expression being strictly valid in the rigid filament limit. The average filament force results from the product of the cumulative size fraction x = x ( L , ℓ p , ρ ˆ 1 ) , where the filament is in contact with the wall, times the buckling force on a filament of size Lc ≈ L, namely, Fs H = x f b ( L ; ℓ p ) . The observed L independence of Fs H implies that x ∝ L-2 for given ( ℓ p , ρ ˆ 1 ) and x ∝ ln ρ ˆ 1

Striation and convection in penumbral filaments

Science.gov (United States)

Spruit, H. C.; Scharmer, G. B.; Löfdahl, M. G.

2010-10-01

Observations with the 1-m Swedish Solar Telescope of the flows seen in penumbral filaments are presented. Time sequences of bright filaments show overturning motions strikingly similar to those seen along the walls of small isolated structures in the active regions. The filaments show outward propagating striations with inclination angles suggesting that they are aligned with the local magnetic field. We interpret it as the equivalent of the striations seen in the walls of small isolated magnetic structures. Their origin is then a corrugation of the boundary between an overturning convective flow inside the filament and the magnetic field wrapping around it. The outward propagation is a combination of a pattern motion due to the downflow observed along the sides of bright filaments, and the Evershed flow. The observed short wavelength of the striation argues against the existence of a dynamically significant horizontal field inside the bright filaments. Its intensity contrast is explained by the same physical effect that causes the dark cores of filaments, light bridges and “canals”. In this way striation represents an important clue to the physics of penumbral structure and its relation with other magnetic structures on the solar surface. We put this in perspective with results from the recent 3-D radiative hydrodynamic simulations. 4 movies are only available in electronic form at http://www.aanda.org

Regularities of intermediate adsorption complex relaxation

International Nuclear Information System (INIS)

Manukova, L.A.

1982-01-01

The experimental data, characterizing the regularities of intermediate adsorption complex relaxation in the polycrystalline Mo-N 2 system at 77 K are given. The method of molecular beam has been used in the investigation. The analytical expressions of change regularity in the relaxation process of full and specific rates - of transition from intermediate state into ''non-reversible'', of desorption into the gas phase and accumUlation of the particles in the intermediate state are obtained

Evolution of filament barbs.

Science.gov (United States)

Liu, R.; Xu, Y.; Wang, H.

We present a selected few cases in which the sense of chirality of filament barbs changed within periods as short as hours. We investigate in detail a quiescent filament on 2003 September 10 and 11. Of its four barbs displaying such changes, only one overlays a small polarity inversion line inside the EUV filament channel (EFC). No magnetic elements with magnitude above the noise level were detected at the endpoints of all barbs. In particular, a pair of barbs first approached toward, and then departed from, each other in Halpha , with the barb endpoints migrating as far as ˜ 10 arcsec. We conclude that the evolution of the barbs was driven by flux emergence and cancellation of small bipolar units at the EFC border.

Filamentation of Campylobacter in broth cultures

Directory of Open Access Journals (Sweden)

Nacheervan M Ghaffar

2015-06-01

Full Text Available The transition from rod to filamentous cell morphology has been identified as a response to stressful conditions in many bacterial species and has been ascribed to confer certain survival advantages. Filamentation of Campylobacter jejuni was demonstrated to occur spontaneously on entry in to stationary phase distinguishing it from many other bacteria where a reduction in size is more common. The aim of this study was to investigate the cues that give rise to filamentation of C. jejuni and C. coli and gain insights into the process. Using minimal medium, augmentation of filamentation occurred and it was observed that this morphological change was wide spread amongst C. jejuni strains tested but was not universal in C. coli strains. Filamentation did not appear to be due to release of diffusible molecules, toxic metabolites, or be in response to oxidative stress in the medium. Separated filaments exhibited greater intracellular ATP contents (2.66 to 17.4 fg than spiral forms (0.99 to 1.7 fg and showed enhanced survival in water at 4oC and 37oC compared to spiral cells. These observations support the conclusion that the filaments are adapted to survive extra-intestinal environments. Differences in cell morphology and physiology need to be considered in the context of the design of experimental studies and the methods adopted for the isolation of campylobacters from food, clinical and environmental sources.

Changes in gene expression and cellular architecture in an ovarian cancer progression model.

Directory of Open Access Journals (Sweden)

Amy L Creekmore

Full Text Available BACKGROUND: Ovarian cancer is the fifth leading cause of cancer deaths among women. Early stage disease often remains undetected due the lack of symptoms and reliable biomarkers. The identification of early genetic changes could provide insights into novel signaling pathways that may be exploited for early detection and treatment. METHODOLOGY/PRINCIPAL FINDINGS: Mouse ovarian surface epithelial (MOSE cells were used to identify stage-dependent changes in gene expression levels and signal transduction pathways by mouse whole genome microarray analyses and gene ontology. These cells have undergone spontaneous transformation in cell culture and transitioned from non-tumorigenic to intermediate and aggressive, malignant phenotypes. Significantly changed genes were overrepresented in a number of pathways, most notably the cytoskeleton functional category. Concurrent with gene expression changes, the cytoskeletal architecture became progressively disorganized, resulting in aberrant expression or subcellular distribution of key cytoskeletal regulatory proteins (focal adhesion kinase, α-actinin, and vinculin. The cytoskeletal disorganization was accompanied by altered patterns of serine and tyrosine phosphorylation as well as changed expression and subcellular localization of integral signaling intermediates APC and PKCβII. CONCLUSIONS/SIGNIFICANCE: Our studies have identified genes that are aberrantly expressed during MOSE cell neoplastic progression. We show that early stage dysregulation of actin microfilaments is followed by progressive disorganization of microtubules and intermediate filaments at later stages. These stage-specific, step-wise changes provide further insights into the time and spatial sequence of events that lead to the fully transformed state since these changes are also observed in aggressive human ovarian cancer cell lines independent of their histological type. Moreover, our studies support a link between aberrant cytoskeleton

Plasma Brightenings in a Failed Solar Filament Eruption

Energy Technology Data Exchange (ETDEWEB)

Li, Y.; Ding, M. D., E-mail: yingli@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210023 (China)

2017-03-20

Failed filament eruptions are solar eruptions that are not associated with coronal mass ejections. In a failed filament eruption, the filament materials usually show some ascending and falling motions as well as generating bright EUV emissions. Here we report a failed filament eruption (SOL2016-07-22) that occurred in a quiet-Sun region observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory . In this event, the filament spreads out but gets confined by the surrounding magnetic field. When interacting with the ambient magnetic field, the filament material brightens up and flows along the magnetic field lines through the corona to the chromosphere. We find that some materials slide down along the lifting magnetic structure containing the filament and impact the chromosphere, and through kinetic energy dissipation, cause two ribbon-like brightenings in a wide temperature range. There is evidence suggesting that magnetic reconnection occurs between the filament magnetic structure and the surrounding magnetic fields where filament plasma is heated to coronal temperatures. In addition, thread-like brightenings show up on top of the erupting magnetic fields at low temperatures, which might be produced by an energy imbalance from a fast drop of radiative cooling due to plasma rarefaction. Thus, this single event of a failed filament eruption shows the existence of a variety of plasma brightenings that may be caused by completely different heating mechanisms.

Graphene-based filament material for thermal ionization

Energy Technology Data Exchange (ETDEWEB)

Hewitt, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Shick, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Siegfried, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-09-19

The use of graphene oxide materials for thermal ionization mass spectrometry analysis of plutonium and uranium has been investigated. Filament made from graphene oxide slurries have been 3-D printed. A method for attaching these filaments to commercial thermal ionization post assemblies has been devised. Resistive heating of the graphene based filaments under high vacuum showed stable operation in excess of 4 hours. Plutonium ion production has been observed in an initial set of filaments spiked with the Pu 128 Certified Reference Material.

Footpoint detection and mass-motion in chromospheric filaments

Science.gov (United States)

V, Aparna; Hardersen, P. S.; Martin, S. F.

2013-07-01

A quiescent region on the Sun containing three filaments is used to study the properties of mass motion. This study determines if the footpoints or end-points of the filaments are the locations from where mass gets injected into the filaments. Several hypotheses have been put forth in the past to determine how a filament acquires mass. Trapping of coronal mass in the filament channel due to condensation (Martin, 1996) and injection of mass into the filaments during magnetic reconnection (Priest, et al., 1995) are some of the speculations. This study looks for indications for injection of mass via chromospheric footpoints. The data consists of blue (Hα-0.5 Å) and red (Hα+0.5 Å) wing high resolution Hα images of the W29N37 region of the Sun taken on Oct 30, 2010, from 1200 - 1600 UT. The Dutch Open Telescope was used to obtain the data. The images are aligned and animated to see Doppler motion in the fibrils. Smaller fibrils merge to form longer ones; barbs appear and disappear in one of the long filaments and is seen moving along the length of the filament. A region with no typical filament-like absorption feature is observed to be continuously receiving mass. Fibrils appear to be converging from opposite sides along what appears to be a neutral line; mass motion is seen in these fibrils as well. An eruption occurs in a region of fibrils lumped together at the end of the first hour (1300 UT) followed by plage brightening at 1430 UT near one of the filament regions. Helioviewer (Panasenco, et al., 2011) is used for aligning the images; GIMP is used for precision alignment and animation. Each frame in the sequence is studied carefully to note changes in the filament regions. The footpoints of the filaments are determined by the changes observed in the position of the filament ‘legs’ in each frame. Variations in the magnetic polarity corresponding to changes observed in the chromosphere are analyzed using HMI magnetograms. Bright and dark points on the

Thick Filament Protein Network, Functions, and Disease Association.

Science.gov (United States)

Wang, Li; Geist, Janelle; Grogan, Alyssa; Hu, Li-Yen R; Kontrogianni-Konstantopoulos, Aikaterini

2018-03-13

Sarcomeres consist of highly ordered arrays of thick myosin and thin actin filaments along with accessory proteins. Thick filaments occupy the center of sarcomeres where they partially overlap with thin filaments. The sliding of thick filaments past thin filaments is a highly regulated process that occurs in an ATP-dependent manner driving muscle contraction. In addition to myosin that makes up the backbone of the thick filament, four other proteins which are intimately bound to the thick filament, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles. Consistent with this, mutations in the respective genes have been associated with idiopathic and congenital forms of skeletal and cardiac myopathies. In this review, we aim to summarize our current knowledge on the molecular structure, subcellular localization, interacting partners, function, modulation via posttranslational modifications, and disease involvement of these five major proteins that comprise the thick filament of striated muscle cells. © 2018 American Physiological Society. Compr Physiol 8:631-709, 2018. Copyright © 2018 American Physiological Society. All rights reserved.

Filament shape versus coronal potential magnetic field structure

Science.gov (United States)

Filippov, B.

2016-01-01

Solar filament shape in projection on disc depends on the structure of the coronal magnetic field. We calculate the position of polarity inversion lines (PILs) of coronal potential magnetic field at different heights above the photosphere, which compose the magnetic neutral surface, and compare with them the distribution of the filament material in Hα chromospheric images. We found that the most of the filament material is enclosed between two PILs, one at a lower height close to the chromosphere and one at a higher level, which can be considered as a height of the filament spine. Observations of the same filament on the limb by the Solar Terrestrial Relations Observatory spacecraft confirm that the height of the spine is really very close to the value obtained from the PIL and filament border matching. Such matching can be used for filament height estimations in on-disc observations. Filament barbs are housed within protruding sections of the low-level PIL. On the base of simple model, we show that the similarity of the neutral surfaces in potential and non-potential fields with the same sub-photospheric sources is the reason for the found tendency for the filament material to gather near the potential-field neutral surface.

Phenotypic variability within the inclusion body spectrum of basophilic inclusion body disease and neuronal intermediate filament inclusion disease in frontotemporal lobar degenerations with FUS-positive inclusions.

Science.gov (United States)

Gelpi, Ellen; Lladó, Albert; Clarimón, Jordi; Rey, Maria Jesús; Rivera, Rosa Maria; Ezquerra, Mario; Antonell, Anna; Navarro-Otano, Judith; Ribalta, Teresa; Piñol-Ripoll, Gerard; Pérez, Anna; Valldeoriola, Francesc; Ferrer, Isidre

2012-09-01

Basophilic inclusion body disease and neuronal intermediate filament inclusion disease (NIFID) are rare diseases included among frontotemporal lobar degenerations with FUS-positive inclusions (FTLD-FUS). We report clinical and pathologic features of 2 new patients and reevaluate neuropathologic characteristics of 2 previously described cases, including an early-onset case of basophilic inclusion body disease (aged 38 years) with a 5-year disease course and abundant FUS-positive inclusion bodies and 3 NIFID cases. One NIFID case (aged 37 years) presented with early-onset psychiatric disturbances and rapidly progressive cognitive decline. Two NIFID cases had later onset (aged 64 years and 70 years) and complex neurologic deficits. Postmortem neuropathologic studies in late-onset NIFID cases disclosed α-internexin-positive "hyaline conglomerate"-type inclusions that were positive with 1 commercial anti-FUS antibody directed to residues 200 and 250, but these were negative to amino acids 90 and 220 of human FUS. Early-onset NIFID had similar inclusions that were positive with both commercial anti-FUS antibodies. Genetic testing performed on all cases revealed no FUS gene mutations. These findings indicate that phenotypic variability in NIFID, including clinical manifestations and particular neuropathologic findings, may be related to the age at onset and individual differences in the evolution of lesions.

Fabrication of PLA Filaments and its Printable Performance

Science.gov (United States)

Liu, Wenjie; Zhou, Jianping; Ma, Yuming; Wang, Jie; Xu, Jie

2017-12-01

Fused deposition modeling (FDM) is a typical 3D printing technology and preparation of qualified filaments is the basis. In order to prepare polylactic acid (PLA) filaments suitable for personalized FDM 3D printing, this article investigated the effect of factors such as extrusion temperature and screw speed on the diameter, surface roughness and ultimate tensile stress of the obtained PLA filaments. The optimal process parameters for fabrication of qualified filaments were determined. Further, the printable performance of the obtained PLA filaments for 3D objects was preliminarily explored.

Terahertz waves radiated from two noncollinear femtosecond plasma filaments

Energy Technology Data Exchange (ETDEWEB)

Du, Hai-Wei; Hoshina, Hiromichi; Otani, Chiko, E-mail: otani@riken.jp [Terahertz Sensing and Imaging Research Team, RIKEN Center for Advanced Photonics, RIKEN, Sendai, Miyagi 980-0845 (Japan); Midorikawa, Katsumi [Attosecond Science Research Team, RIKEN Center for Advanced Photonics, RIKEN, Wako, Saitama 351-0198 (Japan)

2015-11-23

Terahertz (THz) waves radiated from two noncollinear femtosecond plasma filaments with a crossing angle of 25° are investigated. The irradiated THz waves from the crossing filaments show a small THz pulse after the main THz pulse, which was not observed in those from single-filament scheme. Since the position of the small THz pulse changes with the time-delay of two filaments, this phenomenon can be explained by a model in which the small THz pulse is from the second filament. The denser plasma in the overlap region of the filaments changes the movement of space charges in the plasma, thereby changing the angular distribution of THz radiation. As a result, this schematic induces some THz wave from the second filament to propagate along the path of the THz wave from the first filament. Thus, this schematic alters the direction of the THz radiation from the filamentation, which can be used in THz wave remote sensing.

On the properties of a bundle of flexible actin filaments in an optical trap.

Science.gov (United States)

Perilli, Alessia; Pierleoni, Carlo; Ciccotti, Giovanni; Ryckaert, Jean-Paul

2016-06-28

We establish the statistical mechanics framework for a bundle of Nf living and uncrosslinked actin filaments in a supercritical solution of free monomers pressing against a mobile wall. The filaments are anchored normally to a fixed planar surface at one of their ends and, because of their limited flexibility, they grow almost parallel to each other. Their growing ends hit a moving obstacle, depicted as a second planar wall, parallel to the previous one and subjected to a harmonic compressive force. The force constant is denoted as the trap strength while the distance between the two walls as the trap length to make contact with the experimental optical trap apparatus. For an ideal solution of reactive filaments and free monomers at fixed free monomer chemical potential μ1, we obtain the general expression for the grand potential from which we derive averages and distributions of relevant physical quantities, namely, the obstacle position, the bundle polymerization force, and the number of filaments in direct contact with the wall. The grafted living filaments are modeled as discrete Wormlike chains, with F-actin persistence length ℓp, subject to discrete contour length variations ±d (the monomer size) to model single monomer (de)polymerization steps. Rigid filaments (ℓp = ∞), either isolated or in bundles, all provide average values of the stalling force in agreement with Hill's predictions Fs (H)=NfkBTln(ρ1/ρ1c)/d, independent of the average trap length. Here ρ1 is the density of free monomers in the solution and ρ1c its critical value at which the filament does not grow nor shrink in the absence of external forces. Flexible filaments (ℓp < ∞) instead, for values of the trap strength suitable to prevent their lateral escape, provide an average bundle force and an average trap length slightly larger than the corresponding rigid cases (few percents). Still the stalling force remains nearly independent on the average trap length, but results from the

Identification of microRNA-Like RNAs in the filamentous fungus Trichoderma reesei by solexa sequencing.

Directory of Open Access Journals (Sweden)

Kang Kang

Full Text Available microRNAs (miRNAs are non-coding small RNAs (sRNAs capable of negatively regulating gene expression. Recently, microRNA-like small RNAs (milRNAs were discovered in several filamentous fungi but not yet in Trichoderma reesei, an industrial filamentous fungus that can secrete abundant hydrolases. To explore the presence of milRNA in T. reesei and evaluate their expression under induction of cellulose, two T. reesei sRNA libraries of cellulose induction (IN and non-induction (CON were generated and sequenced using Solexa sequencing technology. A total of 726 and 631 sRNAs were obtained from the IN and CON samples, respectively. Global expression analysis showed an extensively differential expression of sRNAs in T. reesei under the two conditions. Thirteen predicted milRNAs were identified in T. reesei based on the short hairpin structure analysis. The milRNA profiles obtained in deep sequencing were further validated by RT-qPCR assay. Computational analysis predicted a number of potential targets relating to many processes including regulation of enzyme expression. The presence and differential expression of T. reesei milRNAs imply that milRNA might play a role in T. reesei growth and cellulase induction. This work lays foundation for further functional study of fungal milRNAs and their industrial application.

[Expression of vimentin and GFAP and development of the retina in the trout].

Science.gov (United States)

De Guevara, R; Pairault, C; Pinganaud, G

1994-08-01

The glial cell development was studied during the edification of the retina and the optic tract, in a teleost, the rainbow trout. The intermediate filament proteins, vimentin and glial fibrillary acidic protein (GFAP) were visualized by an indirect immunohistochemical method. Results show that both vimentin and GFAP are early expressed in the developing retina and, particularly in the Müller cells, a coexpression of vimentin and GFAP is observed from embryonic to adult stages. The ganglion cell layer and the optic fiber layer both exhibit GFAP-positive structures. The deep staining for GFAP is also seen in the optic nerve and induces us to credit astrocyte-like cells with a leading role in the pattern formation of this tract.

Self-assembly of designed supramolecular magnetic filaments of different shapes

Energy Technology Data Exchange (ETDEWEB)

Novak, E.V. [Ural Federal University, Lenin Av. 51, Ekaterinburg (Russian Federation); Rozhkov, D.A., E-mail: d.a.rozhkov@gmail.com [Ural Federal University, Lenin Av. 51, Ekaterinburg (Russian Federation); Sanchez, P.A. [University of Vienna, Sensengasse 8, Vienna (Austria); Kantorovich, S.S. [Ural Federal University, Lenin Av. 51, Ekaterinburg (Russian Federation); University of Vienna, Sensengasse 8, Vienna (Austria)

2017-06-01

In the present work we study via molecular dynamics simulations filaments of ring and linear shape. Filaments are made of magnetic nanoparticles, possessing a point dipole in their centres. Particles in filaments are crosslinked in a particular way, so that the deviation of the neighbouring dipoles from the head-to-tail orientation is penalised by the bond. We show how the conformation of a single chain and ring filament changes on cooling for different lengths. We also study filament pairs, by fixing filaments at a certain distance and analysing the impact of inter-filament interaction on the equilibrium configurations. Our study opens a perspective to investigate the dispersions of filaments, both theoretically and numerically, by using effective potentials. - Highlights: • Single filament study. • Magnetic particles crosslinked in chains and rings. • Magnetic filament interactions.

A comparison study of a solar active-region eruptive filament and a neighboring non-eruptive filament

Science.gov (United States)

Jiang, Chao-Wei; Wu, Shi-Tsan; Feng, Xue-Shang; Hu, Qiang

2016-01-01

Solar active region (AR) 11283 is a very magnetically complex region and it has produced many eruptions. However, there exists a non-eruptive filament in the plage region just next to an eruptive one in the AR, which gives us an opportunity to perform a comparison analysis of these two filaments. The coronal magnetic field extrapolated using our CESE-MHD-NLFFF code reveals that two magnetic flux ropes (MFRs) exist in the same extrapolation box supporting these two filaments, respectively. Analysis of the magnetic field shows that the eruptive MFR contains a bald-patch separatrix surface (BPSS) cospatial very well with a pre-eruptive EUV sigmoid, which is consistent with the BPSS model for coronal sigmoids. The magnetic dips of the non-eruptive MFRs match Hα observation of the non-eruptive filament strikingly well, which strongly supports the MFR-dip model for filaments. Compared with the non-eruptive MFR/filament (with a length of about 200 Mm), the eruptive MFR/filament is much smaller (with a length of about 20 Mm), but it contains most of the magnetic free energy in the extrapolation box and holds a much higher free energy density than the non-eruptive one. Both the MFRs are weakly twisted and cannot trigger kink instability. The AR eruptive MFR is unstable because its axis reaches above a critical height for torus instability, at which the overlying closed arcades can no longer confine the MFR stably. On the contrary, the quiescent MFR is very firmly held by its overlying field, as its axis apex is far below the torus-instability threshold height. Overall, this comparison investigation supports that an MFR can exist prior to eruption and the ideal MHD instability can trigger an MFR eruption.

A comparison study of a solar active-region eruptive filament and a neighboring non-eruptive filament

International Nuclear Information System (INIS)

Jiang, Chao-Wei; Feng, Xue-Shang; Wu, Shi-Tsan; Hu, Qiang

2016-01-01

Solar active region (AR) 11283 is a very magnetically complex region and it has produced many eruptions. However, there exists a non-eruptive filament in the plage region just next to an eruptive one in the AR, which gives us an opportunity to perform a comparison analysis of these two filaments. The coronal magnetic field extrapolated using our CESE–MHD–NLFFF code reveals that two magnetic flux ropes (MFRs) exist in the same extrapolation box supporting these two filaments, respectively. Analysis of the magnetic field shows that the eruptive MFR contains a bald-patch separatrix surface (BPSS) cospatial very well with a pre-eruptive EUV sigmoid, which is consistent with the BPSS model for coronal sigmoids. The magnetic dips of the non-eruptive MFRs match Hα observation of the non-eruptive filament strikingly well, which strongly supports the MFR-dip model for filaments. Compared with the non-eruptive MFR/filament (with a length of about 200 Mm), the eruptive MFR/filament is much smaller (with a length of about 20 Mm), but it contains most of the magnetic free energy in the extrapolation box and holds a much higher free energy density than the non-eruptive one. Both the MFRs are weakly twisted and cannot trigger kink instability. The AR eruptive MFR is unstable because its axis reaches above a critical height for torus instability, at which the overlying closed arcades can no longer confine the MFR stably. On the contrary, the quiescent MFR is very firmly held by its overlying field, as its axis apex is far below the torus-instability threshold height. Overall, this comparison investigation supports that an MFR can exist prior to eruption and the ideal MHD instability can trigger an MFR eruption. (paper)

Helical beating of an actuated elastic filament

International Nuclear Information System (INIS)

Coq, Nais; Roure, Olivia du; Fermigier, Marc; Bartolo, Denis

2009-01-01

We investigate the propulsive force resulting from the rotation of a flexible filament in the low Reynolds number regime. Using a simple linear model, we establish the nonlinear torque-force relations for two torque-driven actuation modes. When the rotation of the filament is induced by two perpendicular transverse oscillating torques, the propulsive force increases monotonically with the torque amplitude. Conversely, when a constant axial torque is applied, the torque-force characteristics displays an unstable branch, related to a discontinuous transition in the shape of the filament. We characterize this shape transition using two geometrical parameters, quantifying the wrapping around and the collapse on the axis of the filament. The proposed theoretical description correctly accounts for our experimental observations and reveals a strong dependence of the filament dynamics on the anchoring conditions.

Fundamentals of Filament Interaction

Science.gov (United States)

2017-05-19

AFRL-AFOSR-VA-TR-2017-0110 FUNDAMENTALS OF FILAMENT INTERACTION Martin Richardson UNIVERSITY OF CENTRAL FLORIDA Final Report 06/02/2017 DISTRIBUTION...of Filament Interaction 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA95501110001 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Martin Richardson 5d. PROJECT...NAME OF RESPONSIBLE PERSON Martin Richardson a. REPORT b. ABSTRACT c. THIS PAGE 19b. TELEPHONE NUMBER (Include area code) 407-823-6819 Standard Form

Filaments in simulations of molecular cloud formation

Energy Technology Data Exchange (ETDEWEB)

Gómez, Gilberto C.; Vázquez-Semadeni, Enrique [Centro de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Campus Morelia Apartado Postal 3-72, 58090 Morelia, Michoacán (Mexico)

2014-08-20

We report on the filaments that develop self-consistently in a new numerical simulation of cloud formation by colliding flows. As in previous studies, the forming cloud begins to undergo gravitational collapse because it rapidly acquires a mass much larger than the average Jeans mass. Thus, the collapse soon becomes nearly pressureless, proceeding along its shortest dimension first. This naturally produces filaments in the cloud and clumps within the filaments. The filaments are not in equilibrium at any time, but instead are long-lived flow features through which the gas flows from the cloud to the clumps. The filaments are long-lived because they accrete from their environment while simultaneously accreting onto the clumps within them; they are essentially the locus where the flow changes from accreting in two dimensions to accreting in one dimension. Moreover, the clumps also exhibit a hierarchical nature: the gas in a filament flows onto a main, central clump but other, smaller-scale clumps form along the infalling gas. Correspondingly, the velocity along the filament exhibits a hierarchy of jumps at the locations of the clumps. Two prominent filaments in the simulation have lengths ∼15 pc and masses ∼600 M {sub ☉} above density n ∼ 10{sup 3} cm{sup –3} (∼2 × 10{sup 3} M {sub ☉} at n > 50 cm{sup –3}). The density profile exhibits a central flattened core of size ∼0.3 pc and an envelope that decays as r {sup –2.5} in reasonable agreement with observations. Accretion onto the filament reaches a maximum linear density rate of ∼30 M {sub ☉} Myr{sup –1} pc{sup –1}.

Thermal and Chemical Evolution of Collapsing Filaments

Energy Technology Data Exchange (ETDEWEB)

Gray, William J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Scannapieco, Evan [Arizona State Univ., Mesa, AZ (United States). School of Earth and Space Exploration

2013-01-15

Intergalactic filaments form the foundation of the cosmic web that connect galaxies together, and provide an important reservoir of gas for galaxy growth and accretion. Here we present very high resolution two-dimensional simulations of the thermal and chemical evolution of such filaments, making use of a 32 species chemistry network that tracks the evolution of key molecules formed from hydrogen, oxygen, and carbon. We study the evolution of filaments over a wide range of parameters including the initial density, initial temperature, strength of the dissociating UV background, and metallicity. In low-redshift, Z ≈ 0.1Z_⊙ filaments, the evolution is determined completely by the initial cooling time. If this is sufficiently short, the center of the filament always collapses to form dense, cold core containing a substantial fraction of molecules. In high-redshift, Z = 10^-3Z_⊙ filaments, the collapse proceeds much more slowly. This is due mostly to the lower initial temperatures, which leads to a much more modest increase in density before the atomic cooling limit is reached, making subsequent molecular cooling much less efficient. Finally, we study how the gravitational potential from a nearby dwarf galaxy affects the collapse of the filament and compare this to NGC 5253, a nearby starbusting dwarf galaxy thought to be fueled by the accretion of filament gas. In contrast to our fiducial case, a substantial density peak forms at the center of the potential. This peak evolves faster than the rest of the filament due to the increased rate at which chemical species form and cooling occur. We find that we achieve similar accretion rates as NGC 5253, but our two-dimensional simulations do not recover the formation of the giant molecular clouds that are seen in radio observations.

Ultraviolet treatment on high performance filaments

International Nuclear Information System (INIS)

Gu Huang

2005-01-01

Quartz, Kevlar, carbon, and glass filaments were irradiated by ultraviolet ray with various periods. Tensile strength of the treated fibres was tested and analyzed, and the outward appearance of the treated filaments was shown

Observations of the Growth of an Active Region Filament

Science.gov (United States)

Yang, Bo

2017-04-01

We present observations of the growth of an active region filament caused by magnetic interactions among the filament and its adjacent superpenumbral filament (SF) and dark thread-like structures (T). Multistep reconnections are identified during the whole growing process. Magnetic flux convergence and cancellation occurring at the positive footpoint region of the filament is the first step reconnection, which resulted in the filament bifurcating into two sets of intertwined threads. One set anchored in situ, while the other set moved toward and interacted with the SF and part of T. This indicates the second step reconnection, which gave rise to the disappearance of the SF and the formation of a long thread-like structure that connects the far ends of the filament and T. The long thread-like structure further interacted with the T and then separated into two parts, representing the third step reconnection. Finally, another similar long thread-like structure, which intertwined with the fixed filament threads, appeared. Hαobservations show that this twisted structure is a longer sinistral filament. Based on the observed photospheric vector magnetograms, we performed a non-linear force-free field extrapolation to reconstruct the magnetic fields above the photosphere and found that the coronal magnetic field lines associated with the filament consists of two twisted flux ropes winding around each other. These results suggest that magnetic interactions among filaments and their adjacent SFs and T could lead to the growth of the filaments, and the filament is probably supported in a flux rope.

Colored fused filament fabrication

OpenAIRE

Song, Haichuan; Lefebvre, Sylvain

2017-01-01

Filament fused fabrication is the method of choice for printing 3D models at low cost, and is the de-facto standard for hobbyists, makers and schools. Unfortunately, filament printers cannot truly reproduce colored objects. The best current techniques rely on a form of dithering exploiting occlusion, that was only demonstrated for shades of two base colors and that behaves differently depending on surface slope. We explore a novel approach for 3D printing colored objects, capable of creating ...

Positrusion Filament Recycling System, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — TUI proposes a novel process to produce 3d printer feedstock filament out of scrap ABS on the ISS. Currently the plastic filament materials that most 3d printers use...

Hydrodynamic interaction induced spontaneous rotation of coupled active filaments.

Science.gov (United States)

Jiang, Huijun; Hou, Zhonghuai

2014-12-14

We investigate the coupled dynamics of active filaments with long range hydrodynamic interactions (HI). Remarkably, we find that filaments can rotate spontaneously under the same conditions in which a single filament alone can only move in translation. Detailed analysis reveals that the emergence of coupled rotation originates from an asymmetric flow field associated with HI which breaks the symmetry of translational motion when filaments approach. The breaking is then further stabilized by HI to form self-sustained coupled rotation. Intensive simulations show that coupled rotation forms easily when one filament tends to collide with the front-half of the other. For head-to-tail approaching, we observe another interesting HI-induced coupled motion, where filaments move together in the form of one following the other. Moreover, the radius of coupled rotation increases exponentially as the rigidity of the filament increases, which suggests that HI are also important for the alignment of rigid-rod-like filaments which has been assumed to be solely a consequence of direct collisions.

Star-forming Filament Models

International Nuclear Information System (INIS)

Myers, Philip C.

2017-01-01

New models of star-forming filamentary clouds are presented in order to quantify their properties and to predict their evolution. These 2D axisymmetric models describe filaments that have no core, one low-mass core, and one cluster-forming core. They are based on Plummer-like cylinders and spheroids that are bounded by a constant-density surface of finite extent. In contrast to 1D Plummer-like models, they have specific values of length and mass, they approximate observed column density maps, and their distributions of column density ( N -pdfs) are pole-free. Each model can estimate the star-forming potential of a core-filament system by identifying the zone of gas dense enough to form low-mass stars and by counting the number of enclosed thermal Jeans masses. This analysis suggests that the Musca central filament may be near the start of its star-forming life, with enough dense gas to make its first ∼3 protostars, while the Coronet filament is near the midpoint of its star formation, with enough dense gas to add ∼8 protostars to its ∼20 known stars. In contrast, L43 appears to be near the end of its star-forming life, since it lacks enough dense gas to add any new protostars to the two young stellar objectsalready known.

Star-forming Filament Models

Energy Technology Data Exchange (ETDEWEB)

Myers, Philip C., E-mail: pmyers@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2017-03-20

New models of star-forming filamentary clouds are presented in order to quantify their properties and to predict their evolution. These 2D axisymmetric models describe filaments that have no core, one low-mass core, and one cluster-forming core. They are based on Plummer-like cylinders and spheroids that are bounded by a constant-density surface of finite extent. In contrast to 1D Plummer-like models, they have specific values of length and mass, they approximate observed column density maps, and their distributions of column density ( N -pdfs) are pole-free. Each model can estimate the star-forming potential of a core-filament system by identifying the zone of gas dense enough to form low-mass stars and by counting the number of enclosed thermal Jeans masses. This analysis suggests that the Musca central filament may be near the start of its star-forming life, with enough dense gas to make its first ∼3 protostars, while the Coronet filament is near the midpoint of its star formation, with enough dense gas to add ∼8 protostars to its ∼20 known stars. In contrast, L43 appears to be near the end of its star-forming life, since it lacks enough dense gas to add any new protostars to the two young stellar objectsalready known.

Evidence for Mixed Helicity in Erupting Filaments

Science.gov (United States)

Muglach, K.; Wang, Y.-M.; Kliem, B.

2009-09-01

Erupting filaments are sometimes observed to undergo a rotation about the vertical direction as they rise. This rotation of the filament axis is generally interpreted as a conversion of twist into writhe in a kink-unstable magnetic flux rope. Consistent with this interpretation, the rotation is usually found to be clockwise (as viewed from above) if the post-eruption arcade has right-handed helicity, but counterclockwise if it has left-handed helicity. Here, we describe two non-active-region filament events recorded with the Extreme-Ultraviolet Imaging Telescope on the Solar and Heliospheric Observatory in which the sense of rotation appears to be opposite to that expected from the helicity of the post-event arcade. Based on these observations, we suggest that the rotation of the filament axis is, in general, determined by the net helicity of the erupting system, and that the axially aligned core of the filament can have the opposite helicity sign to the surrounding field. In most cases, the surrounding field provides the main contribution to the net helicity. In the events reported here, however, the helicity associated with the filament "barbs" is opposite in sign to and dominates that of the overlying arcade.

A method for 3D-reconstruction of a muscle thick filament using the tilt series images of a single filament electron tomogram.

Science.gov (United States)

Márquez, G; Pinto, A; Alamo, L; Baumann, B; Ye, F; Winkler, H; Taylor, K; Padrón, R

2014-05-01

Myosin interacting-heads (MIH) motifs are visualized in 3D-reconstructions of thick filaments from striated muscle. These reconstructions are calculated by averaging methods using images from electron micrographs of grids prepared using numerous filament preparations. Here we propose an alternative method to calculate the 3D-reconstruction of a single thick filament using only a tilt series images recorded by electron tomography. Relaxed thick filaments, prepared from tarantula leg muscle homogenates, were negatively stained. Single-axis tilt series of single isolated thick filaments were obtained with the electron microscope at a low electron dose, and recorded on a CCD camera by electron tomography. An IHRSR 3D-recontruction was calculated from the tilt series images of a single thick filament. The reconstruction was enhanced by including in the search stage dual tilt image segments while only single tilt along the filament axis is usually used, as well as applying a band pass filter just before the back projection. The reconstruction from a single filament has a 40 Å resolution and clearly shows the presence of MIH motifs. In contrast, the electron tomogram 3D-reconstruction of the same thick filament - calculated without any image averaging and/or imposition of helical symmetry - only reveals MIH motifs infrequently. This is - to our knowledge - the first application of the IHRSR method to calculate a 3D reconstruction from tilt series images. This single filament IHRSR reconstruction method (SF-IHRSR) should provide a new tool to assess structural differences between well-ordered thick (or thin) filaments in a grid by recording separately their electron tomograms. Copyright © 2014 Elsevier Inc. All rights reserved.

A filament supported by different magnetic field configurations

Science.gov (United States)

Guo, Y.; Schmieder, B.; Démoulin, P.; Wiegelmann, T.; Aulanier, G.; Török, T.; Bommier, V.

2011-08-01

A nonlinear force-free magnetic field extrapolation of vector magnetogram data obtained by THEMIS/MTR on 2005 May 27 suggests the simultaneous existence of different magnetic configurations within one active region filament: one part of the filament is supported by field line dips within a flux rope, while the other part is located in dips within an arcade structure. Although the axial field chirality (dextral) and the magnetic helicity (negative) are the same along the whole filament, the chiralities of the filament barbs at different sections are opposite, i.e., right-bearing in the flux rope part and left-bearing in the arcade part. This argues against past suggestions that different barb chiralities imply different signs of helicity of the underlying magnetic field. This new finding about the chirality of filaments will be useful to associate eruptive filaments and magnetic cloud using the helicity parameter in the Space Weather Science.

Topology of interaction between titin and myosin thick filaments.

Science.gov (United States)

Kellermayer, Miklós; Sziklai, Dominik; Papp, Zsombor; Decker, Brennan; Lakatos, Eszter; Mártonfalvi, Zsolt

2018-05-05

Titin is a giant protein spanning between the Z- and M-lines of the sarcomere. In the A-band titin is associated with the myosin thick filament. It has been speculated that titin may serve as a blueprint for thick-filament formation due to the super-repeat structure of its A-band domains. Accordingly, titin might provide a template that determines the length and structural periodicity of the thick filament. Here we tested the titin ruler hypothesis by mixing titin and myosin at in situ stoichiometric ratios (300 myosins per 12 titins) in buffers of different ionic strength (KCl concentration range 100-300 mM). The topology of the filamentous complexes was investigated with atomic force microscopy. We found that the samples contained distinct, segregated populations of titin molecules and myosin thick filaments. We were unable to identify complexes in which myosin molecules were regularly associated to either mono- or oligomeric titin in either relaxed or stretched states of the titin filaments. Thus, the electrostatically driven self-association is stronger in both myosin and titin than their binding to each other, and it is unlikely that titin functions as a geometrical template for thick-filament formation. However, when allowed to equilibrate configurationally, long myosin thick filaments appeared with titin oligomers attached to their surface. The titin meshwork formed on the thick-filament surface may play a role in controlling thick-filament length by regulating the structural dynamics of myosin molecules and placing a mechanical limit on the filament length. Copyright © 2018 Elsevier Inc. All rights reserved.

Lifetime of titanium filament at constant current

International Nuclear Information System (INIS)

Chou, T.S.; Lanni, C.

1981-01-01

Titanium Sublimation Pump (TSP) represents the most efficient and the least expensive method to produce Ultra High Vacuum (UHV) in storage rings. In ISABELLE, a proton storage accelerator under construction at Brookhaven National Laboratory, for example, TSP provides a pumping speed for hydrogen of > 2 x 10 6 l/s. Due to the finite life of titanium filaments, new filaments have to be switched in before the end of filament burn out, to ensure smooth operation of the accelerator. Therefore, several operational modes that can be used to activate the TSP were studied. The constant current mode is a convenient way of maintaining constant evaporating rate by increasing the power input while the filament diameter decreases as titanium evaporates. The filaments used in this experiment were standard Varian 916-0024 filaments made of Ti 85%, Mo 15% alloy. During their lifetime at a constant current of 48 amperes, the evaporation rate rose to a maximum at about 10% of their life and then flattened out to a constant value, 0.25 g/hr. The maximum evaporation rate occurs coincidently with the recrystallization of 74% Ti 26% Mo 2 from microstructure crystalline at higher titanium concentration to macrostructure crystalline at lower titanium concentration. As the macrocrystal grows, the slip plane develops at the grain boundary resulting in high resistance at the slip plane which will eventually cause the filament burn out due to local heating

Biophysics of filament length regulation by molecular motors

International Nuclear Information System (INIS)

Kuan, Hui-Shun; Betterton, M D

2013-01-01

Regulating physical size is an essential problem that biological organisms must solve from the subcellular to the organismal scales, but it is not well understood what physical principles and mechanisms organisms use to sense and regulate their size. Any biophysical size-regulation scheme operates in a noisy environment and must be robust to other cellular dynamics and fluctuations. This work develops theory of filament length regulation inspired by recent experiments on kinesin-8 motor proteins, which move with directional bias on microtubule filaments and alter microtubule dynamics. Purified kinesin-8 motors can depolymerize chemically-stabilized microtubules. In the length-dependent depolymerization model, the rate of depolymerization tends to increase with filament length, because long filaments accumulate more motors at their tips and therefore shorten more quickly. When balanced with a constant filament growth rate, this mechanism can lead to a fixed polymer length. However, the mechanism by which kinesin-8 motors affect the length of dynamic microtubules in cells is less clear. We study the more biologically realistic problem of microtubule dynamic instability modulated by a motor-dependent increase in the filament catastrophe frequency. This leads to a significant decrease in the mean filament length and a narrowing of the filament length distribution. The results improve our understanding of the biophysics of length regulation in cells. (paper)

Physical principles of filamentous protein self-assembly kinetics

Science.gov (United States)

Michaels, Thomas C. T.; Liu, Lucie X.; Meisl, Georg; Knowles, Tuomas P. J.

2017-04-01

The polymerization of proteins and peptides into filamentous supramolecular structures is an elementary form of self-organization of key importance to the functioning biological systems, as in the case of actin biofilaments that compose the cellular cytoskeleton. Aberrant filamentous protein self-assembly, however, is associated with undesired effects and severe clinical disorders, such as Alzheimer’s and Parkinson’s diseases, which, at the molecular level, are associated with the formation of certain forms of filamentous protein aggregates known as amyloids. Moreover, due to their unique physicochemical properties, protein filaments are finding extensive applications as biomaterials for nanotechnology. With all these different factors at play, the field of filamentous protein self-assembly has experienced tremendous activity in recent years. A key question in this area has been to elucidate the microscopic mechanisms through which filamentous aggregates emerge from dispersed proteins with the goal of uncovering the underlying physical principles. With the latest developments in the mathematical modeling of protein aggregation kinetics as well as the improvement of the available experimental techniques it is now possible to tackle many of these complex systems and carry out detailed analyses of the underlying microscopic steps involved in protein filament formation. In this paper, we review some classical and modern kinetic theories of protein filament formation, highlighting their use as a general strategy for quantifying the molecular-level mechanisms and transition states involved in these processes.

On the fragmentation of filaments in a molecular cloud simulation

Science.gov (United States)

Chira, R.-A.; Kainulainen, J.; Ibáñez-Mejía, J. C.; Henning, Th.; Mac Low, M.-M.

2018-03-01

Context. The fragmentation of filaments in molecular clouds has attracted a lot of attention recently as there seems to be a close relation between the evolution of filaments and star formation. The study of the fragmentation process has been motivated by simple analytical models. However, only a few comprehensive studies have analysed the evolution of filaments using numerical simulations where the filaments form self-consistently as part of large-scale molecular cloud evolution. Aim. We address the early evolution of parsec-scale filaments that form within individual clouds. In particular, we focus on three questions: How do the line masses of filaments evolve? How and when do the filaments fragment? How does the fragmentation relate to the line masses of the filaments? Methods: We examine three simulated molecular clouds formed in kiloparsec-scale numerical simulations performed with the FLASH adaptive mesh refinement magnetohydrodynamic code. The simulations model a self-gravitating, magnetised, stratified, supernova-driven interstellar medium, including photoelectric heating and radiative cooling. We follow the evolution of the clouds for 6 Myr from the time self-gravity starts to act. We identify filaments using the DisPerSe algorithm, and compare the results to other filament-finding algorithms. We determine the properties of the identified filaments and compare them with the predictions of analytic filament stability models. Results: The average line masses of the identified filaments, as well as the fraction of mass in filamentary structures, increases fairly continuously after the onset of self-gravity. The filaments show fragmentation starting relatively early: the first fragments appear when the line masses lie well below the critical line mass of Ostriker's isolated hydrostatic equilibrium solution ( 16 M⊙ pc-1), commonly used as a fragmentation criterion. The average line masses of filaments identified in three-dimensional volume density cubes

Flux Cancellation Leading to CME Filament Eruptions

Science.gov (United States)

Popescu, Roxana M.; Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.

2016-01-01

Solar filaments are strands of relatively cool, dense plasma magnetically suspended in the lower density hotter solar corona. They trace magnetic polarity inversion lines (PILs) in the photosphere below, and are supported against gravity at heights of up to approx.100 Mm above the chromosphere by the magnetic field in and around them. This field erupts when it is rendered unstable, often by magnetic flux cancellation or emergence at or near the PIL. We have studied the evolution of photospheric magnetic flux leading to ten observed filament eruptions. Specifically, we look for gradual magnetic changes in the neighborhood of the PIL prior to and during eruption. We use Extreme Ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA), and magnetograms from the Helioseismic and Magnetic Imager (HMI), both on board the Solar Dynamics Observatory (SDO), to study filament eruptions and their photospheric magnetic fields. We examine whether flux cancellation or/and emergence leads to filament eruptions. We find that continuous flux cancellation was present at the PIL for many hours prior to each eruption. We present two CME-producing eruptions in detail and find the following: (a) the pre-eruption filament-holding core field is highly sheared and appears in the shape of a sigmoid above the PIL; (b) at the start of the eruption the opposite arms of the sigmoid reconnect in the middle above the site of (tether-cutting) flux cancellation at the PIL; (c) the filaments first show a slow-rise, followed by a fast-rise as they erupt. We conclude that these two filament eruptions result from flux cancellation in the middle of the sheared field, and thereafter evolve in agreement with the standard model for a CME/flare filament eruption from a closed bipolar magnetic field [flux cancellation (van Ballegooijen and Martens 1989 and Moore and Roumelrotis 1992) and runaway tether-cutting (Moore et. al 2001)].

Optical spectroscopy using gas-phase femtosecond laser filamentation.

Science.gov (United States)

Odhner, Johanan; Levis, Robert

2014-01-01

Femtosecond laser filamentation occurs as a dynamic balance between the self-focusing and plasma defocusing of a laser pulse to produce ultrashort radiation as brief as a few optical cycles. This unique source has many properties that make it attractive as a nonlinear optical tool for spectroscopy, such as propagation at high intensities over extended distances, self-shortening, white-light generation, and the formation of an underdense plasma. The plasma channel that constitutes a single filament and whose position in space can be controlled by its input parameters can span meters-long distances, whereas multifilamentation of a laser beam can be sustained up to hundreds of meters in the atmosphere. In this review, we briefly summarize the current understanding and use of laser filaments for spectroscopic investigations of molecules. A theoretical framework of filamentation is presented, along with recent experimental evidence supporting the established understanding of filamentation. Investigations carried out on vibrational and rotational spectroscopy, filament-induced breakdown, fluorescence spectroscopy, and backward lasing are discussed.

Various Barbs in Solar Filaments

Science.gov (United States)

Filippov, Boris

2017-07-01

Interest to lateral details of the solar filament shape named barbs, motivated by their relationship to filament chirality and helicity, showed their different orientation relative to the expected direction of the magnetic field. While the majority of barbs are stretched along the field, some barbs seem to be transversal to it and are referred to as anomalous barbs. We analyse the deformation of helical field lines by a small parasitic polarity using a simple flux rope model with a force-free field. A rather small and distant source of parasitic polarity stretches the bottom parts of the helical lines in its direction creating a lateral extension of dips below the flux-rope axis. They can be considered as normal barbs of the filament. A stronger and closer source of parasitic polarity makes the flux-rope field lines to be convex below its axis and creates narrow and deep dips near its position. As a result, the narrow structure, with thin threads across it, is formed whose axis is nearly perpendicular to the field. The structure resembles an anomalous barb. Hence, the presence of anomalous barbs does not contradict the flux-rope structure of a filament.

Heat shock gene expression and cytoskeletal alterations in mouse neuroblastoma cells

NARCIS (Netherlands)

Bergen en Henegouwen, P.M.P. van; Linnemans, W.A.M.

The cytoskeleton of neuroblastoma cells, clone Neuro 2A, is altered by two stress conditions: heat shock and arsenite treatment. Microtubules are reorganized, intermediate filaments are aggregated around the nucleus, and the number of stress fibers is reduced. Since both stress modalities induce

Numerical simulation of laser filamentation in underdense plasma

International Nuclear Information System (INIS)

Yu Lichun; Chen Zhihua; Tu Qinfen

2000-01-01

Developing process of filamentation and effect of characteristic parameters in underdense plasma have been studied using numerical simulation method. Production and development of two-dimensional cylinder filamentation instability were presented clearly. The results indicate incidence laser intensity and plasma background density are important factors affecting convergent intensity. At the same time, it was showed that different laser wavelength or different electron background density could affect filamentation process. The results are consistent with theory and experiments of alien reports. It can provide reference for restraining filamentation

Beam wandering of femtosecond laser filament in air.

Science.gov (United States)

Yang, Jing; Zeng, Tao; Lin, Lie; Liu, Weiwei

2015-10-05

The spatial wandering of a femtosecond laser filament caused by the filament heating effect in air has been studied. An empirical formula has also been derived from the classical Karman turbulence model, which determines quantitatively the displacement of the beam center as a function of the propagation distance and the effective turbulence structure constant. After fitting the experimental data with this formula, the effective turbulence structure constant has been estimated for a single filament generated in laboratory environment. With this result, one may be able to estimate quantitatively the displacement of a filament over long distance propagation and interpret the practical performance of the experiments assisted by femtosecond laser filamentation, such as remote air lasing, pulse compression, high order harmonic generation (HHG), etc.

Overexpression of neurofilament H disrupts normal cell structure and function

Science.gov (United States)

Szebenyi, Gyorgyi; Smith, George M.; Li, Ping; Brady, Scott T.

2002-01-01

Studying exogenously expressed tagged proteins in live cells has become a standard technique for evaluating protein distribution and function. Typically, expression levels of experimentally introduced proteins are not regulated, and high levels are often preferred to facilitate detection. However, overexpression of many proteins leads to mislocalization and pathologies. Therefore, for normative studies, moderate levels of expression may be more suitable. To understand better the dynamics of intermediate filament formation, transport, and stability in a healthy, living cell, we inserted neurofilament heavy chain (NFH)-green fluorescent protein (GFP) fusion constructs in adenoviral vectors with tetracycline (tet)-regulated promoters. This system allows for turning on or off the synthesis of NFH-GFP at a selected time, for a defined period, in a dose-dependent manner. We used this inducible system for live cell imaging of changes in filament structure and cell shape, motility, and transport associated with increasing NFH-GFP expression. Cells with low to intermediate levels of NFH-GFP were structurally and functionally similar to neighboring, nonexpressing cells. In contrast, overexpression led to pathological alterations in both filament organization and cell function. Copyright 2002 Wiley-Liss, Inc.

Dimensional quantization effects in the thermodynamics of conductive filaments

Science.gov (United States)

Niraula, D.; Grice, C. R.; Karpov, V. G.

2018-06-01

We consider the physical effects of dimensional quantization in conductive filaments that underlie operations of some modern electronic devices. We show that, as a result of quantization, a sufficiently thin filament acquires a positive charge. Several applications of this finding include the host material polarization, the stability of filament constrictions, the equilibrium filament radius, polarity in device switching, and quantization of conductance.

The THMIS-MTR observation of a active region filament

Science.gov (United States)

Zong, W. G.; Tang, Y. H.; Fang, C.

We present some THMIS-MTR observations of a active region filament on September 4, 2002. The full stokes parameters of the filament were obtained in Hα, CaII 8542 and FeI 6302. By use of the data with high spatial resolution(0.44" per pixel), we probed the fine structure of the filament and gave out the parameters at the barbs' endpoints, including intensity, velocity and longitudinal magnetic field. Comparing the quiescent filament which we have discussed before, we find that: 1)The velocities of the barbs' endpoints are much bigger in the active region filament, the values are more than one thousand meters per second. 2)The barbs' endpoints terminate at the low logitudinal magnetic field in the active region filament, too.

Physical principles of filamentous protein self-assembly kinetics

International Nuclear Information System (INIS)

Michaels, Thomas C T; Liu, Lucie X; Meisl, Georg; Knowles, Tuomas P J

2017-01-01

The polymerization of proteins and peptides into filamentous supramolecular structures is an elementary form of self-organization of key importance to the functioning biological systems, as in the case of actin biofilaments that compose the cellular cytoskeleton. Aberrant filamentous protein self-assembly, however, is associated with undesired effects and severe clinical disorders, such as Alzheimer’s and Parkinson’s diseases, which, at the molecular level, are associated with the formation of certain forms of filamentous protein aggregates known as amyloids. Moreover, due to their unique physicochemical properties, protein filaments are finding extensive applications as biomaterials for nanotechnology. With all these different factors at play, the field of filamentous protein self-assembly has experienced tremendous activity in recent years. A key question in this area has been to elucidate the microscopic mechanisms through which filamentous aggregates emerge from dispersed proteins with the goal of uncovering the underlying physical principles. With the latest developments in the mathematical modeling of protein aggregation kinetics as well as the improvement of the available experimental techniques it is now possible to tackle many of these complex systems and carry out detailed analyses of the underlying microscopic steps involved in protein filament formation. In this paper, we review some classical and modern kinetic theories of protein filament formation, highlighting their use as a general strategy for quantifying the molecular-level mechanisms and transition states involved in these processes. (topical review)

Transition from linear- to nonlinear-focusing regime in filamentation

Science.gov (United States)

Lim, Khan; Durand, Magali; Baudelet, Matthieu; Richardson, Martin

2014-01-01

Laser filamentation in gases is often carried out in the laboratory with focusing optics to better stabilize the filament, whereas real-world applications of filaments frequently involve collimated or near-collimated beams. It is well documented that geometrical focusing can alter the properties of laser filaments and, consequently, a transition between a collimated and a strongly focused filament is expected. Nevertheless, this transition point has not been identified. Here, we propose an analytical method to determine the transition, and show that it corresponds to an actual shift in the balance of physical mechanisms governing filamentation. In high-NA conditions, filamentation is primarily governed by geometrical focusing and plasma effects, while the Kerr nonlinearity plays a more significant role as NA decreases. We find the transition between the two regimes to be relatively insensitive to the intrinsic laser parameters, and our analysis agrees well with a wide range of parameters found in published literature. PMID:25434678

Immunohistochemical Examination for the Distribution of Podoplanin-Expressing Cells in Developing Mouse Molar Tooth Germs

Science.gov (United States)

Imaizumi, Yuri; Amano, Ikuko; Tsuruga, Eichi; Kojima, Hiroshi; Sawa, Yoshihiko

2010-01-01

We recently reported the expression of podoplanin in the apical bud of adult mouse incisal tooth. This study was aimed to investigate the distribution of podoplanin-expressing cells in mouse tooth germs at several developing stages. At the bud stage podoplanin was expressed in oral mucous epithelia and in a tooth bud. At the cap stage podoplanin was expressed on inner and outer enamel epithelia but not in mesenchymal cells expressing the neural crest stem cell marker nestin. At the early bell stage nestin and podoplanin were expressed in cervical loop and odontoblasts. At the root formation stage both nestin and podoplanin were weakly expressed in odontoblasts generating radicular dentin. Podoplanin expression was also found in the Hertwig epithelial sheath. These results suggest that epithelial cells of developing tooth germ acquire the ability to express nestin, and that tooth germ epithelial cells maintain the ability to express podoplanin in oral mucous epithelia. The expression of podoplanin in odontoblasts was induced as tooth germ development advanced, but was suppressed with the completion of the primary dentin, suggesting that podoplanin may be involved in the cell growth of odontoblasts. Nestin may function as an intermediate filament that binds podoplanin in odontoblasts. PMID:21060740

Bundling of elastic filaments induced by hydrodynamic interactions

Science.gov (United States)

Man, Yi; Page, William; Poole, Robert J.; Lauga, Eric

2017-12-01

Peritrichous bacteria swim in viscous fluids by rotating multiple helical flagellar filaments. As the bacterium swims forward, all its flagella rotate in synchrony behind the cell in a tight helical bundle. When the bacterium changes its direction, the flagellar filaments unbundle and randomly reorient the cell for a short period of time before returning to their bundled state and resuming swimming. This rapid bundling and unbundling is, at its heart, a mechanical process whereby hydrodynamic interactions balance with elasticity to determine the time-varying deformation of the filaments. Inspired by this biophysical problem, we present in this paper what is perhaps the simplest model of bundling whereby two or more straight elastic filaments immersed in a viscous fluid rotate about their centerline, inducing rotational flows which tend to bend the filaments around each other. We derive an integrodifferential equation governing the shape of the filaments resulting from mechanical balance in a viscous fluid at low Reynolds number. We show that such equation may be evaluated asymptotically analytically in the long-wavelength limit, leading to a local partial differential equation governed by a single dimensionless bundling number. A numerical study of the dynamics predicted by the model reveals the presence of two configuration instabilities with increasing bundling numbers: first to a crossing state where filaments touch at one point and then to a bundled state where filaments wrap along each other in a helical fashion. We also consider the case of multiple filaments and the unbundling dynamics. We next provide an intuitive physical model for the crossing instability and show that it may be used to predict analytically its threshold and adapted to address the transition to a bundling state. We then use a macroscale experimental implementation of the two-filament configuration in order to validate our theoretical predictions and obtain excellent agreement. This long

First intron of nestin gene regulates its expression during C2C12 myoblast ifferentiation

Institute of Scientific and Technical Information of China (English)

Hua Zhong; Zhigang Jin; Yongfeng Chen; Ting Zhang; Wei Bian; Xing Cui; Naihe Jing

2008-01-01

Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China Nestin is an intermediate filament protein expressed in neural progenitor cells and in developing skeletal muscle. Nestin has been widely used as a neural progenitor cell marker. It is well established that the specific expression of the nestin gene in neural progenitor cells is conferred by the neural-specific enhancer located in the second intron of the nestin gene. However, the transcriptional mechanism of nestin expression in developing muscle is still unclear. In this study, we identified a muscle cell-specific enhancer in the first intron of mouse nestin gene in mouse myoblast C2C12 cells.We localized the core enhancer activity to the 291-661 region of the first intron, and showed that the two E-boxes in the core enhancer region were important for enhancer activity in differentiating C2C12 cells. We also showed that MyoD protein was involved in the regulation of nestin expression in the myogenic differentiation of C2C12 cells.

Large scale filaments associated with Milky Way spiral arms

Science.gov (United States)

Wang, Ke; Testi, Leonardo; Ginsburg, Adam; Walmsley, Malcolm; Molinari, Sergio; Schisano, Eugenio

2015-08-01

The ubiquity of filamentary structure at various scales through out the Galaxy has triggered a renewed interest in their formation, evolution, and role in star formation. The largest filaments can reach up to Galactic scale as part of the spiral arm structure. However, such large scale filaments are hard to identify systematically due to limitations in identifying methodology (i.e., as extinction features). We present a new approach to directly search for the largest, coldest, and densest filaments in the Galaxy, making use of sensitive Herschel Hi-GAL data complemented by spectral line cubes. We present a sample of the 9 most prominent Herschel filaments from a pilot search field. These filaments measure 37-99 pc long and 0.6-3.0 pc wide with masses (0.5-8.3)×104 Msun, and beam-averaged (28", or 0.4-0.7 pc) peak H2 column densities of (1.7-9.3)x1022 cm-2. The bulk of the filaments are relatively cold (17-21 K), while some local clumps have a dust temperature up to 25-47 K due to local star formation activities. All the filaments are located within spiral arm model incorporating the latest parallax measurements, we find that 7/9 of them reside within arms, but most are close to arm edges. These filaments are comparable in length to the Galactic scale height and therefore are not simply part of a grander turbulent cascade. These giant filaments, which often contain regularly spaced pc-scale clumps, are much larger than the filaments found in the Herschel Gould's Belt Survey, and they form the upper ends in the filamentary hierarchy. Full operational ALMA and NOEMA will be able to resolve and characterize similar filaments in nearby spiral galaxies, allowing us to compare the star formation in a uniform context of spiral arms.

Intense EM filamentation in relativistic hot plasmas

Energy Technology Data Exchange (ETDEWEB)

Hu, Qiang-Lin [Department of Physics, Jinggangshan University, Ji' an, Jiangxi 343009 (China); Chen, Zhong-Ping [Department of Physics and Institute for Fusion Studies, The University of Texas at Austin, Austin, TX 78712 (United States); Mahajan, Swadesh M., E-mail: mahajan@mail.utexas.edu [Department of Physics and Institute for Fusion Studies, The University of Texas at Austin, Austin, TX 78712 (United States); Department of Physics, School of Natural Sciences, Shiv Nadar University, Uttar Pradesh 201314 (India)

2017-03-03

Highlights: • Breaking up of an intense EM pulse into filaments is a spectacular demonstration of the nonlinear wave-plasma interaction. • Filaments are spectacularly sharper, highly extended and longer lived at relativistic temperatures. • EM energy concentration can trigger new nonlinear phenomena with absolute consequences for high energy density matter. - Abstract: Through 2D particle-in-cell (PIC) simulations, we demonstrate that the nature of filamentation of a high intensity electromagnetic (EM) pulse propagating in an underdense plasma, is profoundly affected at relativistically high temperatures. The “relativistic” filaments are sharper, are dramatically extended (along the direction of propagation), and live much longer than their lower temperature counterparts. The thermally boosted electron inertia is invoked to understand this very interesting and powerful phenomenon.

Recruitment Kinetics of Tropomyosin Tpm3.1 to Actin Filament Bundles in the Cytoskeleton Is Independent of Actin Filament Kinetics.

Science.gov (United States)

Appaduray, Mark A; Masedunskas, Andrius; Bryce, Nicole S; Lucas, Christine A; Warren, Sean C; Timpson, Paul; Stear, Jeffrey H; Gunning, Peter W; Hardeman, Edna C

2016-01-01

The actin cytoskeleton is a dynamic network of filaments that is involved in virtually every cellular process. Most actin filaments in metazoa exist as a co-polymer of actin and tropomyosin (Tpm) and the function of an actin filament is primarily defined by the specific Tpm isoform associated with it. However, there is little information on the interdependence of these co-polymers during filament assembly and disassembly. We addressed this by investigating the recovery kinetics of fluorescently tagged isoform Tpm3.1 into actin filament bundles using FRAP analysis in cell culture and in vivo in rats using intracellular intravital microscopy, in the presence or absence of the actin-targeting drug jasplakinolide. The mobile fraction of Tpm3.1 is between 50% and 70% depending on whether the tag is at the C- or N-terminus and whether the analysis is in vivo or in cultured cells. We find that the continuous dynamic exchange of Tpm3.1 is not significantly impacted by jasplakinolide, unlike tagged actin. We conclude that tagged Tpm3.1 may be able to undergo exchange in actin filament bundles largely independent of the assembly and turnover of actin.

Filamentous Fungi Fermentation

DEFF Research Database (Denmark)

Nørregaard, Anders; Stocks, Stuart; Woodley, John

2014-01-01

Filamentous fungi (including microorganisms such as Aspergillus niger and Rhizopus oryzae) represent an enormously important platform for industrial fermentation. Two particularly valuable features are the high yield coefficients and the ability to secrete products. However, the filamentous...... morphology, together with non-Newtonian rheological properties (shear thinning), result in poor oxygen transfer unless sufficient energy is provided to the fermentation. While genomic research may improve the organisms, there is no doubt that to enable further application in future it will be necessary...... to match such research with studies of oxygen transfer and energy supply to high viscosity fluids. Hence, the implementation of innovative solutions (some of which in principle are already possible) will be essential to ensure the further development of such fermentations....

Mechanical model for filament buckling and growth by phase ordering.

Science.gov (United States)

Rey, Alejandro D; Abukhdeir, Nasser M

2008-02-05

A mechanical model of open filament shape and growth driven by phase ordering is formulated. For a given phase-ordering driving force, the model output is the filament shape evolution and the filament end-point kinematics. The linearized model for the slope of the filament is the Cahn-Hilliard model of spinodal decomposition, where the buckling corresponds to concentration fluctuations. Two modes are predicted: (i) sequential growth and buckling and (ii) simultaneous buckling and growth. The relation among the maximum buckling rate, filament tension, and matrix viscosity is given. These results contribute to ongoing work in smectic A filament buckling.

Laser-induced filaments in the mid-infrared

International Nuclear Information System (INIS)

Zheltikov, A M

2017-01-01

Laser-induced filamentation in the mid-infrared gives rise to unique regimes of nonlinear wave dynamics and reveals in many ways unusual nonlinear-optical properties of materials in this frequency range. The λ 2 scaling of the self-focusing threshold P cr , with radiation wavelength λ , allows the laser powers transmitted by single mid-IR filaments to be drastically increased without the loss of beam continuity and spatial coherence. When extended to the mid-infrared, laser filamentation enables new methods of pulse compression. Often working around the universal physical limitations, it helps generate few-cycle and subcycle field waveforms within an extraordinarily broad range of peak powers, from just a few up to hundreds of P cr . As a part of a bigger picture, laser-induced filamentation in the mid-infrared offers important physical insights into the general properties of the nonlinear-optical response of matter as a function of the wavelength. Unlike their near-infrared counterparts, which can be accurately described within the framework of perturbative nonlinear optics, mid-infrared filaments often entangle perturbative and nonperturbative nonlinear-optical effects, showing clear signatures of strong-field optical physics. With the role of nonperturbative nonlinear-optical phenomena growing, as a general tendency, with the field intensity and the driver wavelength, extension of laser filamentation to even longer driver wavelengths, toward the long-wavelength infrared, promises a hic sunt dracones land. (topical review)

Effect of nickel on the organization of actin filaments in Arabidopsis thaliana primary root cells

International Nuclear Information System (INIS)

Goryunova, I.I.; Krasilenko, Yu.A.; Emets, A.I.; Blyum, Ya.B.

2016-01-01

The influence of one of the most toxic heavy metals - nickel (Ni 2+ ) - on the organization of actin filaments (microfilaments) of different types of Arabidopsis thaliana (L.) root cells is studied in living cells by the laser scanning microscopy. To visualize microfilaments, the A. thaliana line expressing chimeric gene gfp-fabd2 was used. Ni 2+ leads to a significant inhibition of the growth of the main root and disturbs its morphology, causing the swelling of epidermal cells and inducing a large number of abnormally long root hairs. For the first time, it has been shown that Ni 2+ disturbs the organization of actin filaments in cells, leading to morphological changes of a root as the main organ, being the first exposed to the intoxication by soil pollutants. It is found that the most sensitive to its action are actin filaments of epidermal cells of all growth zones of A. thaliana root

Disintegration of an eruptive filament via interactions with quasi-separatrix layers

Science.gov (United States)

Liu, Rui; Chen, Jun; Wang, YuMing

2018-06-01

The disintegration of solar filaments via mass drainage is a frequently observed phenomenon during a variety of filament activities. It is generally considered that the draining of dense filament material is directed by both gravity and magnetic field, yet the detailed process remains elusive. Here we report on a partial filament eruption during which filament material drains downward to the surface not only along the filament's legs, but to a remote flare ribbon through a fan-out curtain-like structure. It is found that the magnetic configuration is characterized by two conjoining dome-like quasi-sepratrix layers (QSLs). The filament is located underneath one QSL dome, whose footprint apparently bounds the major flare ribbons resulting from the filament eruption, whereas the remote flare ribbon matches well with the other QSL dome's far-side footprint. We suggest that the interaction of the filament with the overlying QSLs results in the splitting and disintegration of the filament.

Microwave structure of quiescent solar filaments at high resolution

International Nuclear Information System (INIS)

Gary, D.E.

1986-01-01

High resolution very low altitude maps of a quiescent filament at three frequencies are presented. The spatial resolution (approx. 15'' at 1.45 GHz, approx. 6'' at 4.9 GHz, and approx. 2'' at 15 GHz) is several times better than previously attained. At each frequency, the filament appears as a depression in the quiet Sun background. The depression is measurably wider and longer in extent than the corresponding H alpha filament at 1.45 GHz and 4.9 GHz, indicating that the depression is due in large part to a deficit in coronal density associated with the filament channel. In contrast, the shape of the radio depression at 15 CHz closely matches that of the H alpha filament. In addition, the 15 GHz map shows enhanced emission along both sides of the radio depression. A similar enhancement is seen in an observation of a second filament 4 days later, which suggests that the enhancement is a general feature of filaments. Possible causes of the enhanced emission are explored

Filaments in Lupus I

Science.gov (United States)

Takahashi, Satoko; Rodon, J.; De Gregorio-Monsalvo, I.; Plunkett, A.

2017-06-01

The mechanisms behind the formation of sub-stellar mass sources are key to determine the populations at the low-mass end of the stellar distribution. Here, we present mapping observations toward the Lupus I cloud in C18O(2-1) and 13CO(2-1) obtained with APEX. We have identified a few velocity-coherent filaments. Each contains several substellar mass sources that are also identified in the 1.1mm continuum data (see also SOLA catalogue presentation). We will discuss the velocity structure, fragmentation properties of the identified filaments, and the nature of the detected sources.

Factors limiting SOS expression in log-phase cells of Escherichia coli.

Science.gov (United States)

Massoni, Shawn C; Leeson, Michael C; Long, Jarukit Edward; Gemme, Kristin; Mui, Alice; Sandler, Steven J

2012-10-01

In Escherichia coli, RecA-single-stranded DNA (RecA-ssDNA) filaments catalyze DNA repair, recombination, and induction of the SOS response. It has been shown that, while many (15 to 25%) log-phase cells have RecA filaments, few (about 1%) are induced for SOS. It is hypothesized that RecA's ability to induce SOS expression in log-phase cells is repressed because of the potentially detrimental effects of SOS mutagenesis. To test this, mutations were sought to produce a population where the number of cells with SOS expression more closely equaled the number of RecA filaments. Here, it is shown that deleting radA (important for resolution of recombination structures) and increasing recA transcription 2- to 3-fold with a recAo1403 operator mutation act independently to minimally satisfy this condition. This allows 24% of mutant cells to have elevated levels of SOS expression, a percentage similar to that of cells with RecA-green fluorescent protein (RecA-GFP) foci. In an xthA (exonuclease III gene) mutant where there are 3-fold more RecA loading events, recX (a destabilizer of RecA filaments) must be additionally deleted to achieve a population of cells where the percentage having elevated SOS expression (91%) nearly equals the percentage with at least one RecA-GFP focus (83%). It is proposed that, in the xthA mutant, there are three independent mechanisms that repress SOS expression in log-phase cells. These are the rapid processing of RecA filaments by RadA, maintaining the concentration of RecA below a critical level, and the destabilizing of RecA filaments by RecX. Only the first two mechanisms operate independently in a wild-type cell.

Hot Ta filament resistance in-situ monitoring under silane containing atmosphere

International Nuclear Information System (INIS)

Grunsky, D.; Schroeder, B.

2008-01-01

Monitoring of the electrical resistance of the Ta catalyst during the hot wire chemical vapor deposition (HWCVD) of thin silicon films gives information about filament condition. Using Ta filaments for silane decomposition not only the well known strong changes at the cold ends, but also changes of the central part of the filament were observed. Three different phenomena can be distinguished: silicide (stoichiometric Ta X Si Y alloys) growth on the filament surfaces, diffusion of Si into the Ta filament and thick silicon deposits (TSD) formation on the filament surface. The formation of different tantalum silicides on the surface as well as the in-diffusion of silicon increase the filament resistance, while the TSDs form additional electrical current channels and that result in a decrease of the filament resistance. Thus, the filament resistance behaviour during ageing is the result of the competition between these two processes

Modeling Vertical Plasma Flows in Solar Filament Barbs

Science.gov (United States)

Litvinenko, Y.

2003-12-01

Speeds of observed flows in quiescent solar filaments are typically much less than the local Alfvén speed. This is why the flows in filament barbs can be modeled by perturbing a local magnetostatic solution describing the balance between the Lorentz force, gravity, and gas pressure in a barb. Similarly, large-scale filament flows can be treated as adiabatically slow deformations of a force-free magnetic equilibrium that describes the global structure of a filament. This approach reconciles current theoretical models with the puzzling observational result that some of the flows appear to be neither aligned with the magnetic field nor controlled by gravity.

Large-scale filaments associated with Milky Way spiral arms

Science.gov (United States)

Wang, Ke; Testi, Leonardo; Ginsburg, Adam; Walmsley, C. Malcolm; Molinari, Sergio; Schisano, Eugenio

2015-07-01

The ubiquity of filamentary structure at various scales throughout the Galaxy has triggered a renewed interest in their formation, evolution, and role in star formation. The largest filaments can reach up to Galactic scale as part of the spiral arm structure. However, such large-scale filaments are hard to identify systematically due to limitations in identifying methodology (i.e. as extinction features). We present a new approach to directly search for the largest, coldest, and densest filaments in the Galaxy, making use of sensitive Herschel Hi-GAL (Herschel Infrared Galactic Plane Survey) data complemented by spectral line cubes. We present a sample of the nine most prominent Herschel filaments, including six identified from a pilot search field plus three from outside the field. These filaments measure 37-99 pc long and 0.6-3.0 pc wide with masses (0.5-8.3) × 104 M⊙, and beam-averaged (28 arcsec, or 0.4-0.7 pc) peak H2 column densities of (1.7-9.3)× 1022 cm- 2. The bulk of the filaments are relatively cold (17-21 K), while some local clumps have a dust temperature up to 25-47 K. All the filaments are located within ≲60 pc from the Galactic mid-plane. Comparing the filaments to a recent spiral arm model incorporating the latest parallax measurements, we find that 7/9 of them reside within arms, but most are close to arm edges. These filaments are comparable in length to the Galactic scaleheight and therefore are not simply part of a grander turbulent cascade.

Scanning For Hotspots In Lamp Filaments

Science.gov (United States)

Powers, Charles E.; Van Sant, Tim; Leidecker, Henning

1993-01-01

Scanning photometer designed for use in investigation of failures of incandescent lamp filaments. Maps brightness as function of position along each filament to identify bright (hot) spots, occurring at notches and signifying incipient breaks or rewelds. Also used to measure nonuniformity in outputs of such linear devices as light-emitting diodes, and to measure diffraction patterns of lenses.

Magnetic Fields in the Massive Dense Cores of the DR21 Filament: Weakly Magnetized Cores in a Strongly Magnetized Filament

Energy Technology Data Exchange (ETDEWEB)

Ching, Tao-Chung; Lai, Shih-Ping [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Zhang, Qizhou; Girart, Josep M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138 (United States); Qiu, Keping [School of Astronomy and Space Science, Nanjing University, 163 Xianlin Avenue, Nanjing 210023 (China); Liu, Hauyu B., E-mail: chingtaochung@gmail.com [European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany)

2017-04-01

We present Submillimeter Array 880 μ m dust polarization observations of six massive dense cores in the DR21 filament. The dust polarization shows complex magnetic field structures in the massive dense cores with sizes of 0.1 pc, in contrast to the ordered magnetic fields of the parsec-scale filament. The major axes of the massive dense cores appear to be aligned either parallel or perpendicular to the magnetic fields of the filament, indicating that the parsec-scale magnetic fields play an important role in the formation of the massive dense cores. However, the correlation between the major axes of the cores and the magnetic fields of the cores is less significant, suggesting that during the core formation, the magnetic fields below 0.1 pc scales become less important than the magnetic fields above 0.1 pc scales in supporting a core against gravity. Our analysis of the angular dispersion functions of the observed polarization segments yields a plane-of-sky magnetic field strength of 0.4–1.7 mG for the massive dense cores. We estimate the kinematic, magnetic, and gravitational virial parameters of the filament and the cores. The virial parameters show that the gravitational energy in the filament dominates magnetic and kinematic energies, while the kinematic energy dominates in the cores. Our work suggests that although magnetic fields may play an important role in a collapsing filament, the kinematics arising from gravitational collapse must become more important than magnetic fields during the evolution from filaments to massive dense cores.

The evolution of compositionally and functionally distinct actin filaments.

Science.gov (United States)

Gunning, Peter W; Ghoshdastider, Umesh; Whitaker, Shane; Popp, David; Robinson, Robert C

2015-06-01

The actin filament is astonishingly well conserved across a diverse set of eukaryotic species. It has essentially remained unchanged in the billion years that separate yeast, Arabidopsis and man. In contrast, bacterial actin-like proteins have diverged to the extreme, and many of them are not readily identified from sequence-based homology searches. Here, we present phylogenetic analyses that point to an evolutionary drive to diversify actin filament composition across kingdoms. Bacteria use a one-filament-one-function system to create distinct filament systems within a single cell. In contrast, eukaryotic actin is a universal force provider in a wide range of processes. In plants, there has been an expansion of the number of closely related actin genes, whereas in fungi and metazoa diversification in tropomyosins has increased the compositional variety in actin filament systems. Both mechanisms dictate the subset of actin-binding proteins that interact with each filament type, leading to specialization in function. In this Hypothesis, we thus propose that different mechanisms were selected in bacteria, plants and metazoa, which achieved actin filament compositional variation leading to the expansion of their functional diversity. © 2015. Published by The Company of Biologists Ltd.

Filament to filament bridging and its influence on developing high critical current density in multifilamentary Bi2Sr2CaCu2Ox round wires

International Nuclear Information System (INIS)

Shen, T; Jiang, J; Kametani, F; Trociewitz, U P; Larbalestier, D C; Schwartz, J; Hellstrom, E E

2010-01-01

Increasing the critical current density (J c ) of the multifilamentary round wire Ag/Bi 2 Sr 2 CaCu 2 O x (2212) requires understanding its complicated microstructure, in which extensive bridges between filaments are prominent. In this first through-process quench study of 2212 round wire, we determined how its microstructure develops during a standard partial-melt process and how filament bridging occurs. We found that filaments can bond together in the melt state. As 2212 starts to grow on subsequent cooling, we observed that two types of 2212 bridges form. One type, which we call Type-A bridges, forms within filaments that bonded in the melt; Type-A bridges are single grains that span multiple bonded filaments. The other type, called Type-B bridges, form between discrete filaments through 2212 outgrowths that penetrate into the Ag matrix and intersect with other 2212 outgrowths from adjacent filaments. We believe the ability of these two types of bridges to carry inter-filament current is intrinsically different: Type-A bridges are high- J c inter-filament paths whereas Type-B bridges contain high-angle grain boundaries and are typically weak linked. Slow cooling leads to more filament bonding, more Type-A bridges and a doubling of J c without changing the flux pinning. We suggest that Type-A bridges create a 3D current flow that is vital to developing high J c in multifilamentary 2212 round wire.

In situ ellipsometric study of surface immobilization of flagellar filaments

Energy Technology Data Exchange (ETDEWEB)

Kurunczi, S., E-mail: kurunczi@mfa.kfki.hu [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Nemeth, A.; Huelber, T. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Kozma, P. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Department of Nanotechnology, Research Institute of Chemical and Process Engineering, Faculty of Information Technology, University of Pannonia, Egyetem u. 10, Veszprem, H-8200 (Hungary); Petrik, P. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Jankovics, H. [Department of Nanotechnology, Research Institute of Chemical and Process Engineering, Faculty of Information Technology, University of Pannonia, Egyetem u. 10, Veszprem, H-8200 (Hungary); Sebestyen, A. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Department of Nanotechnology, Research Institute of Chemical and Process Engineering, Faculty of Information Technology, University of Pannonia, Egyetem u. 10, Veszprem, H-8200 (Hungary); Vonderviszt, F. [Department of Photonics, Research Institute for Technical Physics and Materials Science, H-1121, Konkoly Thege Miklos ut 29-33, Budapest (Hungary); Department of Nanotechnology, Research Institute of Chemical and Process Engineering, Faculty of Information Technology, University of Pannonia, Egyetem u. 10, Veszprem, H-8200 (Hungary); Institute of Enzymology, Karolina ut 29-33, Budapest, H-1113 (Hungary); and others

2010-10-15

Protein filaments composed of thousands of subunits are promising candidates as sensing elements in biosensors. In this work in situ spectroscopic ellipsometry is applied to monitor the surface immobilization of flagellar filaments. This study is the first step towards the development of layers of filamentous receptors for sensor applications. Surface activation is performed using silanization and a subsequent glutaraldehyde crosslinking. Structure of the flagellar filament layers immobilized on activated and non-activated Si wafer substrates is determined using a two-layer effective medium model that accounted for the vertical density distribution of flagellar filaments with lengths of 300-1500 nm bound to the surface. The formation of the first interface layer can be explained by the multipoint covalent attachment of the filaments, while the second layer is mainly composed of tail pinned filaments floating upwards with the free parts. As confirmed by atomic force microscopy, covalent immobilization resulted in an increased surface density compared to absorption.

Lighting the universe with filaments.

Science.gov (United States)

Gao, Liang; Theuns, Tom

2007-09-14

The first stars in the universe form when chemically pristine gas heats as it falls into dark-matter potential wells, cools radiatively because of the formation of molecular hydrogen, and becomes self-gravitating. Using supercomputer simulations, we demonstrated that the stars' properties depend critically on the currently unknown nature of the dark matter. If the dark-matter particles have intrinsic velocities that wipe out small-scale structure, then the first stars form in filaments with lengths on the order of the free-streaming scale, which can be approximately 10(20) meters (approximately 3 kiloparsecs, corresponding to a baryonic mass of approximately 10(7) solar masses) for realistic "warm dark matter" candidates. Fragmentation of the filaments forms stars with a range of masses, which may explain the observed peculiar element abundance pattern of extremely metal-poor stars, whereas coalescence of fragments and stars during the filament's ultimate collapse may seed the supermassive black holes that lurk in the centers of most massive galaxies.

The Cape Ghir filament system in August 2009 (NW Africa)

Science.gov (United States)

Sangrà, Pablo; Troupin, Charles; Barreiro-González, Beatriz; Desmond Barton, Eric; Orbi, Abdellatif; Arístegui, Javier

2015-06-01

In the framework of the Canaries-Iberian marine ecosystem Exchanges (CAIBEX) experiment, an interdisciplinary high-resolution survey was conducted in the NW African region of Cape Ghir (30°38'N) during August 2009. The anatomy of a major filament is investigated on scales down to the submesoscale using in situ and remotely sensed data. The filament may be viewed as a system composed of three intimately connected structures: a small, shallow, and cold filament embedded within a larger, deeper, and cool filament and an intrathermocline anticyclonic eddy (ITE). The cold filament, which stretches 110 km offshore, is a shallow feature 60 m deep and 25 km wide, identified by minimal surface temperatures and rich in chlorophyll a. This structure comprises two asymmetrical submesoscale (˜18 km) fronts with jets flowing in opposite directions. The cold filament is embedded near the equatorward boundary of a much broader region of approximately 120 km width and 150 m depth that forms the cool filament and stretches at least 200 km offshore. This cool region, partly resulting from the influence of cold filament, is limited by two asymmetrical mesoscale (˜50 km) frontal boundaries. At the ITE, located north of the cold filament, we observe evidence of downwelling as indicated by a relatively high concentration of particles extending from the surface to more than 200 m depth. We hypothesize that this ITE may act as a sink of carbon and thus the filament system may serve dual roles of offshore carbon export and carbon sink.

Validation of the Amsterdam Dynamic Facial Expression Set--Bath Intensity Variations (ADFES-BIV: A Set of Videos Expressing Low, Intermediate, and High Intensity Emotions.

Directory of Open Access Journals (Sweden)

Tanja S H Wingenbach

Full Text Available Most of the existing sets of facial expressions of emotion contain static photographs. While increasing demand for stimuli with enhanced ecological validity in facial emotion recognition research has led to the development of video stimuli, these typically involve full-blown (apex expressions. However, variations of intensity in emotional facial expressions occur in real life social interactions, with low intensity expressions of emotions frequently occurring. The current study therefore developed and validated a set of video stimuli portraying three levels of intensity of emotional expressions, from low to high intensity. The videos were adapted from the Amsterdam Dynamic Facial Expression Set (ADFES and termed the Bath Intensity Variations (ADFES-BIV. A healthy sample of 92 people recruited from the University of Bath community (41 male, 51 female completed a facial emotion recognition task including expressions of 6 basic emotions (anger, happiness, disgust, fear, surprise, sadness and 3 complex emotions (contempt, embarrassment, pride that were expressed at three different intensities of expression and neutral. Accuracy scores (raw and unbiased (Hu hit rates were calculated, as well as response times. Accuracy rates above chance level of responding were found for all emotion categories, producing an overall raw hit rate of 69% for the ADFES-BIV. The three intensity levels were validated as distinct categories, with higher accuracies and faster responses to high intensity expressions than intermediate intensity expressions, which had higher accuracies and faster responses than low intensity expressions. To further validate the intensities, a second study with standardised display times was conducted replicating this pattern. The ADFES-BIV has greater ecological validity than many other emotion stimulus sets and allows for versatile applications in emotion research. It can be retrieved free of charge for research purposes from the

Validation of the Amsterdam Dynamic Facial Expression Set--Bath Intensity Variations (ADFES-BIV): A Set of Videos Expressing Low, Intermediate, and High Intensity Emotions.

Science.gov (United States)

Wingenbach, Tanja S H; Ashwin, Chris; Brosnan, Mark

2016-01-01

Most of the existing sets of facial expressions of emotion contain static photographs. While increasing demand for stimuli with enhanced ecological validity in facial emotion recognition research has led to the development of video stimuli, these typically involve full-blown (apex) expressions. However, variations of intensity in emotional facial expressions occur in real life social interactions, with low intensity expressions of emotions frequently occurring. The current study therefore developed and validated a set of video stimuli portraying three levels of intensity of emotional expressions, from low to high intensity. The videos were adapted from the Amsterdam Dynamic Facial Expression Set (ADFES) and termed the Bath Intensity Variations (ADFES-BIV). A healthy sample of 92 people recruited from the University of Bath community (41 male, 51 female) completed a facial emotion recognition task including expressions of 6 basic emotions (anger, happiness, disgust, fear, surprise, sadness) and 3 complex emotions (contempt, embarrassment, pride) that were expressed at three different intensities of expression and neutral. Accuracy scores (raw and unbiased (Hu) hit rates) were calculated, as well as response times. Accuracy rates above chance level of responding were found for all emotion categories, producing an overall raw hit rate of 69% for the ADFES-BIV. The three intensity levels were validated as distinct categories, with higher accuracies and faster responses to high intensity expressions than intermediate intensity expressions, which had higher accuracies and faster responses than low intensity expressions. To further validate the intensities, a second study with standardised display times was conducted replicating this pattern. The ADFES-BIV has greater ecological validity than many other emotion stimulus sets and allows for versatile applications in emotion research. It can be retrieved free of charge for research purposes from the corresponding author.

The architecture and fine structure of gill filaments in the brown ...

African Journals Online (AJOL)

Special attention was paid to filament architecture, ennervation of filaments, number and type of cells populating filament epithelia and variations in epithelial cell morphology and cilia ultrastructure. Filament shape was maintained by thickened chi-tln and strategically placed smooth myocytes. The epithelium was populated ...

Isolation and characterization of Candida albicans morphological mutants derepressed for the formation of filamentous hypha-type structures

International Nuclear Information System (INIS)

Gil, C.; Pomes, R.; Nombela, C.

1990-01-01

Several Candida albicans morphological mutants were obtained by a procedure based on a combined treatment with nitrous acid plus UV irradiation and a double-enrichment step to increase the proportion of mutants growing as long filamentous structures. Altered cell morphogenesis in these mutants correlated with an altered colonial phenotype. Two of these mutants, C. albicans NEL102 and NEL103, were selected and characterized. Mutant blastoconidia initiated budding but eventually gave rise to filamentous hypha-type formations. These filaments were long and septate, and they branched very regularly at positions near septa. Calcofluor white (which is known to bind chitin-rich areas) stained septa, branching zones, and filament tips very intensely, as observed under the fluorescence microscope. Wild-type hybrids were obtained by fusing protoplasts of strain NEL102 with B14, another morphological mutant previously described as being permanently pseudomycelial, indicating that genetic determinants responsible for the two altered phenotypes are different. The mutants characterized in this work seemed to sequentially express the morphogenic characteristics of C. albicans, from blastoconidia to hyphae, in the absence of any inducer. Further characterization of these strains could be relevant to gain understanding of the genetic control of dimorphism in this species

Force-velocity measurements of a few growing actin filaments.

Directory of Open Access Journals (Sweden)

Coraline Brangbour

2011-04-01

Full Text Available The polymerization of actin in filaments generates forces that play a pivotal role in many cellular processes. We introduce a novel technique to determine the force-velocity relation when a few independent anchored filaments grow between magnetic colloidal particles. When a magnetic field is applied, the colloidal particles assemble into chains under controlled loading or spacing. As the filaments elongate, the beads separate, allowing the force-velocity curve to be precisely measured. In the widely accepted Brownian ratchet model, the transduced force is associated with the slowing down of the on-rate polymerization. Unexpectedly, in our experiments, filaments are shown to grow at the same rate as when they are free in solution. However, as they elongate, filaments are more confined in the interspace between beads. Higher repulsive forces result from this higher confinement, which is associated with a lower entropy. In this mechanism, the production of force is not controlled by the polymerization rate, but is a consequence of the restriction of filaments' orientational fluctuations at their attachment point.

Mechanical response of melt-spun amorphous filaments

International Nuclear Information System (INIS)

Leal, A A; Reifler, F A; Hufenus, R; Mohanty, G; Michler, J

2014-01-01

High-speed melt spinning of a cyclo-olefin polymer (COP) and a copolyamide (CoPA) have been performed. Differential scanning calorimetry curves of the resulting monofilaments show that they remain in an amorphous state even after hot drawing. Wide angle x-ray diffraction patterns of undrawn and drawn COP filaments show that although the material remains in an amorphous state, a degree of orientation is induced in the polymer after drawing. The amorphous filaments show an enhanced bending recovery with respect to different semi-crystalline monofilaments commercially available. However, single fiber axial compressive testing indicates that the amorphous filaments exhibit a compressive modulus value which is 50% lower than what is observed for a reference semi-crystalline PET filament. Analysis of the compressive strains applied by the bending recovery test indicates that while the maximum applied strains remain well within the region of elastic deformation of the amorphous materials, the threshold between elastic and plastic deformation is reached for the semi-crystalline materials. (paper)

Ponderomotive and thermal filamentation of laser light

International Nuclear Information System (INIS)

Kruer, W.L.

1985-01-01

As targets are irradiated with longer, more energetic pulses of laser light, longer-scalelength plasmas are produced. Filamentation is a potentially important process in such plasmas. In this instability, perturbations in the intensity profile of an incident light beam grow in amplitude, causing the beam to break up into intense filaments. The instability arises when a local increase in the light intensity creates a depression in plasma density either directly, via the ponderomotive force, or indirectly, via enhanced collisional absorption and subsequent plasma expansion. The density depression refracts the light into the lower-density region, enhancing the intensity perturbations. The instability is termed either ponderomotive or thermal filamentation, depending on which mechanism generates the density depression. The analogous process involving the entire beam is called self-focusing. Filamentation can significantly affect laser-plasma coupling. Intensity enhancements can introduce or modify other instabilities, change the location of the energy deposition, and possibly aggravate deleterious collective effects such as hot-electron generation

The calcium-modulated proteins, S100A1 and S100B, as potential regulators of the dynamics of type III intermediate filaments

Directory of Open Access Journals (Sweden)

M. Garbuglia

1999-10-01

Full Text Available The Ca2+-modulated, dimeric proteins of the EF-hand (helix-loop-helix type, S100A1 and S100B, that have been shown to inhibit microtubule (MT protein assembly and to promote MT disassembly, interact with the type III intermediate filament (IF subunits, desmin and glial fibrillary acidic protein (GFAP, with a stoichiometry of 2 mol of IF subunit/mol of S100A1 or S100B dimer and an affinity of 0.5-1.0 µM in the presence of a few micromolar concentrations of Ca2+. Binding of S100A1 and S100B results in inhibition of desmin and GFAP assemblies into IFs and stimulation of the disassembly of preformed desmin and GFAP IFs. S100A1 and S100B interact with a stretch of residues in the N-terminal (head domain of desmin and GFAP, thereby blocking the head-to-tail process of IF elongation. The C-terminal extension of S100A1 (and, likely, S100B represents a critical part of the site that recognizes desmin and GFAP. S100B is localized to IFs within cells, suggesting that it might have a role in remodeling IFs upon elevation of cytosolic Ca2+ concentration by avoiding excess IF assembly and/or promoting IF disassembly in vivo. S100A1, that is not localized to IFs, might also play a role in the regulation of IF dynamics by binding to and sequestering unassembled IF subunits. Together, these observations suggest that S100A1 and S100B may be regarded as Ca2+-dependent regulators of the state of assembly of two important elements of the cytoskeleton, IFs and MTs, and, potentially, of MT- and IF-based activities.

THE APPARATUS FOR ALIGNMENT OF THE PHOTOMETRIC LAMP FILAMENT

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V. A. Dlugunovich

2015-01-01

Full Text Available During photometric measurements involving the use of photometric lamps it is necessary that the filament of lamp takes a strictly predetermined position with respect to the photodetector and the optical axis of the photometric setup. The errors in positioning of alignment filament with respect to the optical axis of the measuring system lead to increase the uncertainty of measurement of the photometric characteristics of the light sources. A typical method for alignment of filament of photometric lamps is based on the use a diopter tubes (telescopes. Using this method, the mounting of filament to the required position is carried out by successive approximations, which requires special concentration and a lot of time. The aim of this work is to develop an apparatus for alignment which allows simultaneous alignment of the filament of lamps in two mutually perpendicular planes. The method and apparatus for alignment of the photometric lamp filament during measurements of the photometric characteristics of light sources based on two digital video cameras is described in this paper. The apparatus allows to simultaneously displaying the image of lamps filament on the computer screen in two mutually perpendicular planes. The apparatus eliminates a large number of functional units requiring elementwise alignment and reduces the time required to carry out the alignment. The apparatus also provides the imaging of lamps filament with opaque coated on the bulb. The apparatus is used at the National standard of light intensity and illuminance units of the Republic of Belarus. 

Impact of matric potential and pore size distribution on growth dynamics of filamentous and non-filamentous soil bacteria.

Science.gov (United States)

Wolf, Alexandra B; Vos, Michiel; de Boer, Wietse; Kowalchuk, George A

2013-01-01

The filamentous growth form is an important strategy for soil microbes to bridge air-filled pores in unsaturated soils. In particular, fungi perform better than bacteria in soils during drought, a property that has been ascribed to the hyphal growth form of fungi. However, it is unknown if, and to what extent, filamentous bacteria may also display similar advantages over non-filamentous bacteria in soils with low hydraulic connectivity. In addition to allowing for microbial interactions and competition across connected micro-sites, water films also facilitate the motility of non-filamentous bacteria. To examine these issues, we constructed and characterized a series of quartz sand microcosms differing in matric potential and pore size distribution and, consequently, in connection of micro-habitats via water films. Our sand microcosms were used to examine the individual and competitive responses of a filamentous bacterium (Streptomyces atratus) and a motile rod-shaped bacterium (Bacillus weihenstephanensis) to differences in pore sizes and matric potential. The Bacillus strain had an initial advantage in all sand microcosms, which could be attributed to its faster growth rate. At later stages of the incubation, Streptomyces became dominant in microcosms with low connectivity (coarse pores and dry conditions). These data, combined with information on bacterial motility (expansion potential) across a range of pore-size and moisture conditions, suggest that, like their much larger fungal counterparts, filamentous bacteria also use this growth form to facilitate growth and expansion under conditions of low hydraulic conductivity. The sand microcosm system developed and used in this study allowed for precise manipulation of hydraulic properties and pore size distribution, thereby providing a useful approach for future examinations of how these properties influence the composition, diversity and function of soil-borne microbial communities.

Impact of matric potential and pore size distribution on growth dynamics of filamentous and non-filamentous soil bacteria.

Directory of Open Access Journals (Sweden)

Alexandra B Wolf

Full Text Available The filamentous growth form is an important strategy for soil microbes to bridge air-filled pores in unsaturated soils. In particular, fungi perform better than bacteria in soils during drought, a property that has been ascribed to the hyphal growth form of fungi. However, it is unknown if, and to what extent, filamentous bacteria may also display similar advantages over non-filamentous bacteria in soils with low hydraulic connectivity. In addition to allowing for microbial interactions and competition across connected micro-sites, water films also facilitate the motility of non-filamentous bacteria. To examine these issues, we constructed and characterized a series of quartz sand microcosms differing in matric potential and pore size distribution and, consequently, in connection of micro-habitats via water films. Our sand microcosms were used to examine the individual and competitive responses of a filamentous bacterium (Streptomyces atratus and a motile rod-shaped bacterium (Bacillus weihenstephanensis to differences in pore sizes and matric potential. The Bacillus strain had an initial advantage in all sand microcosms, which could be attributed to its faster growth rate. At later stages of the incubation, Streptomyces became dominant in microcosms with low connectivity (coarse pores and dry conditions. These data, combined with information on bacterial motility (expansion potential across a range of pore-size and moisture conditions, suggest that, like their much larger fungal counterparts, filamentous bacteria also use this growth form to facilitate growth and expansion under conditions of low hydraulic conductivity. The sand microcosm system developed and used in this study allowed for precise manipulation of hydraulic properties and pore size distribution, thereby providing a useful approach for future examinations of how these properties influence the composition, diversity and function of soil-borne microbial communities.

MATERIAL SUPPLY AND MAGNETIC CONFIGURATION OF AN ACTIVE REGION FILAMENT

Energy Technology Data Exchange (ETDEWEB)

Zou, P.; Fang, C.; Chen, P. F.; Yang, K.; Hao, Q. [School of Astronomy and Space Science, Nanjing University, Nanjing 210023 (China); Cao, Wenda, E-mail: fangc@nju.edu.cn [Big Bear Solar Observatory, New Jersey Institute of Technology, 40386 North Shore Lane, Big Bear City, CA 92314 (United States)

2016-11-10

It is important to study the fine structures of solar filaments with high-resolution observations, since it can help us understand the magnetic and thermal structures of the filaments and their dynamics. In this paper, we study a newly formed filament located inside the active region NOAA 11762, which was observed by the 1.6 m New Solar Telescope at Big Bear Solar Observatory from 16:40:19 UT to 17:07:58 UT on 2013 June 5. As revealed by the H α filtergrams, cool material is seen to be injected into the filament spine with a speed of 5–10 km s{sup -1}. At the source of the injection, brightenings are identified in the chromosphere, which are accompanied by magnetic cancellation in the photosphere, implying the importance of magnetic reconnection in replenishing the filament with plasmas from the lower atmosphere. Counter-streamings are detected near one endpoint of the filament, with the plane-of-the-sky speed being 7–9 km s{sup -1} in the H α red-wing filtergrams and 9–25 km s{sup -1} in the blue-wing filtergrams. The observations are indicative that this active region filament is supported by a sheared arcade without magnetic dips, and the counter-streamings are due to unidirectional flows with alternative directions, rather than due to the longitudinal oscillations of filament threads as in many other filaments.

Statistical Study of the Magnetic Field Orientation in Solar Filaments

Science.gov (United States)

Hanaoka, Yoichiro; Sakurai, Takashi

2017-12-01

We have carried out a statistical study of the average orientation of the magnetic field in solar filaments with respect to their axes for more than 400 samples, based on data taken with daily full-Sun, full-Stokes spectropolarimetric observations using the He I 1083.0 nm line. The major part of the samples are the filaments in the quiet areas, but those in the active areas are included as well. The average orientation of the magnetic field in filaments shows a systematic property depending on the hemisphere; the direction of the magnetic field in filaments in the northern (southern) hemisphere mostly deviates clockwise (counterclockwise) from their axes, which run along the magnetic polarity inversion line. The deviation angles of the magnetic field from the axes are concentrated between 10° and 30°. This hemispheric pattern is consistent with that revealed for chirality of filament barbs, filament channels, and for other solar features found to possess chirality. For some filaments, it was confirmed that their magnetic field direction is locally parallel to their structure seen in Hα images. Our results for the first time confirmed this hemispheric pattern with the direct observation of the magnetic field in filaments. Interestingly, the filaments which show the opposite magnetic field deviation to the hemispheric pattern, are in many cases found above the polarity inversion line whose ambient photospheric magnetic field has the polarity alignment being opposite to that of active regions following the Hale–Nicholson law.

Hollow cylindrical plasma filament waveguide with discontinuous finite thickness cladding

International Nuclear Information System (INIS)

Alshershby, Mostafa; Hao Zuoqiang; Lin Jingquan

2013-01-01

We have explored here a hollow cylindrical laser plasma multifilament waveguide with discontinuous finite thickness cladding, in which the separation between individual filaments is in the range of several millimeters and the waveguide cladding thickness is in the order of the microwave penetration depth. Such parameters give a closer representation of a realistic laser filament waveguide sustained by a long stable propagation of femtosecond (fs) laser pulses. We report how the waveguide losses depend on structural parameters like normalized plasma filament spacing, filament to filament distance or pitch, normal spatial frequency, and radius of the plasma filament. We found that for typical plasma parameters, the proposed waveguide can support guided modes of microwaves in extremely high frequency even with a cladding consisting of only one ring of plasma filaments. The loss of the microwave radiation is mainly caused by tunneling through the discontinuous finite cladding, i.e., confinement loss, and is weakly dependent on the plasma absorption. In addition, the analysis indicates that the propagation loss is fairly large compared with the loss of a plasma waveguide with a continuous infinite thickness cladding, while they are comparable when using a cladding contains more than one ring. Compared to free space propagation, this waveguide still presents a superior microwave transmission to some distance in the order of the filamentation length; thus, the laser plasma filaments waveguide may be a potential channel for transporting pulsed-modulated microwaves if ensuring a long and stable propagation of fs laser pulses.

The Contributions of the Amino and Carboxy Terminal Domains of Flightin to the Biomechanical Properties of Drosophila Flight Muscle Thick Filaments.

Science.gov (United States)

Gasek, Nathan S; Nyland, Lori R; Vigoreaux, Jim O

2016-04-27

Flightin is a myosin binding protein present in Pancrustacea. In Drosophila, flightin is expressed in the indirect flight muscles (IFM), where it is required for the flexural rigidity, structural integrity, and length determination of thick filaments. Comparison of flightin sequences from multiple Drosophila species revealed a tripartite organization indicative of three functional domains subject to different evolutionary constraints. We use atomic force microscopy to investigate the functional roles of the N-terminal domain and the C-terminal domain that show different patterns of sequence conservation. Thick filaments containing a C-terminal domain truncated flightin (fln(ΔC44)) are significantly shorter (2.68 ± 0.06 μm; p thick filaments containing a full length flightin (fln⁺; 3.21 ± 0.05 μm) and thick filaments containing an N-terminal domain truncated flightin (fln(ΔN62); 3.21 ± 0.06 μm). Persistence length was significantly reduced in fln(ΔN62) (418 ± 72 μm; p thick filament bending propensity. Our results indicate that the flightin amino and carboxy terminal domains make distinct contributions to thick filament biomechanics. We propose these distinct roles arise from the interplay between natural selection and sexual selection given IFM's dual role in flight and courtship behaviors.

Radiosensitivity related to neuroendocrine and endodermal differentation in lung carcinoma lines

International Nuclear Information System (INIS)

Duchesne, G.; Casoni, A.; Pera, M.

1988-01-01

A panel of human lung carcinoma lines was studied with respect to hormone production and intermediate filament expression to distinguish between endodermal and neuroendocrine differentation. An index of the degree of neuroendocrine differentiation of each line was derived from the presence or absence of hormone production, cytokeratins, neurofilaments and an embryonic endodermal cell marker, which allowed identification of three groups showing high, intermediate or low neuroendocrine expression. This grouping correlated well with the in vitro radiosensitivity of the lines, those expressing pure neuroendocrine features being significantly more radiosensitive than those with an endodermal phenotype, with the intermediate group having intermediate sensitivity. Use of such an index might predict those patients likely to benefit from the use of radiotherapy in their management. 30 refs.; 3 figs.; 3 tabs

Extending Femtosecond Filamentation of High Power Laser Propagating in the Atmosphere

Science.gov (United States)

Eisenmann, Shmuel; Sivan, Yonatan; Fibich, Gadi; Zigler, Arie

2008-06-01

We show experimentally for ultrashort laser pulses propagating in air, that the filamentation distance of intense laser pulses in the atmosphere can be extended and controlled with a simple double-lens setup. Using this method we were able to achieve a 20-fold delay of the filamentation distance of non-chirped 120 fs pulses propagating in air, from 16 m to 330 m. At 330 m, the collapsing pulse is sufficiently powerful to create plasma filaments. We also show that the scatter of the filaments at 330 m can be significantly reduced by tilting the second lens. We derive a simple formula for the filamentation distance, and confirm its agreement with the experimental results. We also observe that delaying the onset of filamentation increases the filament length. To the best of our knowledge, this is the longest distance reported in the literature at which plasma filaments were created and controlled. Finally, we show that the peak power at the onset of collapse is significantly higher with the double-lens setup, compared with the standard negative chirping approach.

Giant quiescent solar filament observed with high-resolution spectroscopy

Science.gov (United States)

Kuckein, C.; Verma, M.; Denker, C.

2016-05-01

Aims: An extremely large filament was studied in various layers of the solar atmosphere. The inferred physical parameters and the morphological aspects are compared with smaller quiescent filaments. Methods: A giant quiet-Sun filament was observed with the high-resolution Echelle spectrograph at the Vacuum Tower Telescope at Observatorio del Teide, Tenerife, Spain, on 2011 November 15. A mosaic of spectra (ten maps of 100″ × 182″) was recorded simultaneously in the chromospheric absorption lines Hα and Na I D2. Physical parameters of the filament plasma were derived using cloud model (CM) inversions and line core fits. The spectra were complemented with full-disk filtergrams (He I λ10830 Å, Hα, and Ca II K) of the Chromospheric Telescope (ChroTel) and full-disk magnetograms of the Helioseismic and Magnetic Imager (HMI). Results: The filament had extremely large linear dimensions (~817 arcsec), which corresponds to about 658 Mm along a great circle on the solar surface. A total amount of 175119 Hα contrast profiles were inverted using the CM approach. The inferred mean line-of-sight (LOS) velocity, Doppler width, and source function were similar to previous works of smaller quiescent filaments. However, the derived optical thickness was higher. LOS velocity trends inferred from the Hα line core fits were in accord but weaker than those obtained with CM inversions. Signatures of counter-streaming flows were detected in the filament. The largest brightening conglomerates in the line core of Na I D2 coincided well with small-scale magnetic fields as seen by HMI. Mixed magnetic polarities were detected close to the ends of barbs. The computation of photospheric horizontal flows based on HMI magnetograms revealed flow kernels with a size of 5-8 Mm and velocities of 0.30-0.45 km s-1 at the ends of the filament. Conclusions: The physical properties of extremely large filaments are similar to their smaller counterparts, except for the optical thickness, which in

Design and optimize of 3-axis filament winding machine

Science.gov (United States)

Quanjin, Ma; Rejab, M. R. M.; Idris, M. S.; Bachtiar, B.; Siregar, J. P.; Harith, M. N.

2017-10-01

Filament winding technique is developed as the primary process for composite cylindrical structures fabrication at low cost. Fibres are wound on a rotating mandrel by a filament winding machine where resin impregnated fibres pass through a pay-out eye. This paper aims to develop and optimize a 3-axis, lightweight, practical, efficient, portable filament winding machine to satisfy the customer demand, which can fabricate pipes and round shape cylinders with resins. There are 3 main units on the 3-axis filament winding machine, which are the rotary unit, the delivery unit and control system unit. Comparison with previous existing filament winding machines in the factory, it has 3 degrees of freedom and can fabricate more complex shape specimens based on the mandrel shape and particular control system. The machine has been designed and fabricated on 3 axes movements with control system. The x-axis is for movement of the carriage, the y-axis is the rotation of mandrel and the z-axis is the movement of the pay-out eye. Cylindrical specimens with different dimensions and winding angles were produced. 3-axis automated filament winding machine has been successfully designed with simple control system.

Effect of Filament Fineness on Composite Yarn Residual Torque

Directory of Open Access Journals (Sweden)

Sarıoğlu Esin

2018-03-01

Full Text Available Yarn residual torque or twist liveliness occurs when the twist is imparted to spin the fibers during yarn formation. It causes yarn snarling, which is an undesirable property and can lead the problems for further processes such as weaving and knitting. It affects the spirality of knitted fabrics and skewness of woven fabrics. Generally, yarn residual torque depends on yarn twist, yarn linear density, and fiber properties used. Composite yarns are widely produced to exploit two yarns with different properties such on optimum way at the same time and these yarns can be produced by wrapping sheath fibers around filament core fiber with a certain twist. In this study, the effect of filament fineness used as core component of composite yarn on residual torque was analyzed. Thus, the false twist textured polyester filament yarns with different filament fineness were used to produce composite yarns with different yarn count. The variance analysis was performed to determine the significance of twist liveliness of filament yarns and yarn count on yarn twist liveliness. Results showed that there is a statistically significant differences at significance level of α=0.05 between filament fineness and yarn residual torque of composite yarns.

Filament bundle location influence on coupling losses in superconducting composites

International Nuclear Information System (INIS)

Ito, Daisuke; Koizumi, Misao; Hamajima, Takataro; Nakane, Fumoto.

1983-01-01

The ac losses in multifilamentary superconducting composites with different superconducting filament bundle positions have been measured using the magnetization method in order to reveal the relation between filament bundle position and coupling losses. Loss components depending on dB/dt in a mixed matrix superconducting composite, whose filament bundle is located in a central region surrounded by an outer stabilizing copper sheath, has been compared with another superconducting composite whose stabilizing copper is located in a central region surrounded by an outer filament bundle. In both conductors, key parameters, such as filament twistpitch, wire diameter and amount of copper stabilizer, were almost the same. Applied magnetic field is 2 Tesla with 0.05-2 Tesla/sec field change rate. Experimental results indicate that coupling losses between filaments in the composite with the filament bundle located in the central region is smaller than the composite with the filament bundle located in the outer region. A similar conclusion was reached theoretically by B. Truck. Coupling loss values obtained by the experiment show good agreement with calculated values with the equations proposed by B. Truck. It is also pointed out that a copper stabilizer, divided by the CuNi barrier into small regions, like a honeycomb, causes anomalous increasing in the copper resistivity due to Ni diffusion during heat treatment. (author)

A catalytic oligomeric motor that walks along a filament track

Energy Technology Data Exchange (ETDEWEB)

Huang, Mu-Jie, E-mail: mjhuang@chem.utoronto.ca; Kapral, Raymond, E-mail: rkapral@chem.utoronto.ca [Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6 (Canada)

2015-06-28

Most biological motors in the cell execute chemically powered conformational changes as they walk on biopolymer filaments in order to carry out directed transport functions. Synthetic motors that operate in a similar manner are being studied since they have the potential to perform similar tasks in a variety of applications. In this paper, a synthetic nanomotor that moves along a filament track, without invoking motor conformational changes, is constructed and its properties are studied in detail. The motor is an oligomer comprising three linked beads with specific binding properties. The filament track is a stiff polymer chain, also described by a linear chain of linked coarse-grained molecular groups modeled as beads. Reactions on the filament that are catalyzed by a motor bead and use fuel in the environment, in conjunction within the binding affinities of the motor beads to the filament beads, lead to directed motion. The system operates out of equilibrium due to the state of the filament and supply of fuel. The motor, filament, and surrounding medium are all described at microscopic level that permits a full analysis of the motor motion. A stochastic model that captures the main trends seen in the simulations is also presented. The results of this study point to some of the key features that could be used to construct nanomotors that undergo biased walks powered by chemical reactions on filaments.

A catalytic oligomeric motor that walks along a filament track

Science.gov (United States)

Huang, Mu-Jie; Kapral, Raymond

2015-06-01

Most biological motors in the cell execute chemically powered conformational changes as they walk on biopolymer filaments in order to carry out directed transport functions. Synthetic motors that operate in a similar manner are being studied since they have the potential to perform similar tasks in a variety of applications. In this paper, a synthetic nanomotor that moves along a filament track, without invoking motor conformational changes, is constructed and its properties are studied in detail. The motor is an oligomer comprising three linked beads with specific binding properties. The filament track is a stiff polymer chain, also described by a linear chain of linked coarse-grained molecular groups modeled as beads. Reactions on the filament that are catalyzed by a motor bead and use fuel in the environment, in conjunction within the binding affinities of the motor beads to the filament beads, lead to directed motion. The system operates out of equilibrium due to the state of the filament and supply of fuel. The motor, filament, and surrounding medium are all described at microscopic level that permits a full analysis of the motor motion. A stochastic model that captures the main trends seen in the simulations is also presented. The results of this study point to some of the key features that could be used to construct nanomotors that undergo biased walks powered by chemical reactions on filaments.

A catalytic oligomeric motor that walks along a filament track

International Nuclear Information System (INIS)

Huang, Mu-Jie; Kapral, Raymond

2015-01-01

Most biological motors in the cell execute chemically powered conformational changes as they walk on biopolymer filaments in order to carry out directed transport functions. Synthetic motors that operate in a similar manner are being studied since they have the potential to perform similar tasks in a variety of applications. In this paper, a synthetic nanomotor that moves along a filament track, without invoking motor conformational changes, is constructed and its properties are studied in detail. The motor is an oligomer comprising three linked beads with specific binding properties. The filament track is a stiff polymer chain, also described by a linear chain of linked coarse-grained molecular groups modeled as beads. Reactions on the filament that are catalyzed by a motor bead and use fuel in the environment, in conjunction within the binding affinities of the motor beads to the filament beads, lead to directed motion. The system operates out of equilibrium due to the state of the filament and supply of fuel. The motor, filament, and surrounding medium are all described at microscopic level that permits a full analysis of the motor motion. A stochastic model that captures the main trends seen in the simulations is also presented. The results of this study point to some of the key features that could be used to construct nanomotors that undergo biased walks powered by chemical reactions on filaments

Morgellons disease: a filamentous borrelial dermatitis

OpenAIRE

Middelveen, Marianne J; Stricker, Raphael B

2016-01-01

Marianne J Middelveen, Raphael B Stricker International Lyme and Associated Diseases Society, Bethesda, MD, USA Abstract: Morgellons disease (MD) is a dermopathy characterized by multicolored filaments that lie under, are embedded in, or project from skin. Although MD was initially considered to be a delusional disorder, recent studies have demonstrated that the dermopathy is associated with tickborne infection, that the filaments are composed of keratin and collagen, and that they resu...

Nestin Expression Reflects Formation, Revascularization and Reinnervation of New Myofibers in Regenerating Rat Hind Limb Skeletal Muscles

Czech Academy of Sciences Publication Activity Database

Čížková, D.; Soukup, Tomáš; Mokrý, J.

2009-01-01

Roč. 189, č. 5 (2009), s. 338-347 ISSN 1422-6405 Institutional research plan: CEZ:AV0Z50110509 Keywords : intermediate filaments * muscle transplantation * muscle regeneration Subject RIV: ED - Physiology Impact factor: 3.322, year: 2009

Preserved filamentous microbial biosignatures in the Brick Flat gossan, Iron Mountain, California

Science.gov (United States)

Williams, Amy J.; Sumner, Dawn Y.; Alpers, Charles N.; Karunatillake, Suniti; Hofmann, Beda A

2015-01-01

A variety of actively precipitating mineral environments preserve morphological evidence of microbial biosignatures. One such environment with preserved microbial biosignatures is the oxidized portion of a massive sulfide deposit, or gossan, such as that at Iron Mountain, California. This gossan may serve as a mineralogical analogue to some ancient martian environments due to the presence of oxidized iron and sulfate species, and minerals that only form in acidic aqueous conditions, in both environments. Evaluating the potential biogenicity of cryptic textures in such martian gossans requires an understanding of how microbial textures form biosignatures on Earth. The iron-oxide-dominated composition and morphology of terrestrial, nonbranching filamentous microbial biosignatures may be distinctive of the underlying formation and preservation processes. The Iron Mountain gossan consists primarily of ferric oxide (hematite), hydrous ferric oxide (HFO, predominantly goethite), and jarosite group minerals, categorized into in situ gossan, and remobilized iron deposits. We interpret HFO filaments, found in both gossan types, as HFO-mineralized microbial filaments based in part on (1) the presence of preserved central filament lumina in smooth HFO mineral filaments that are likely molds of microbial filaments, (2) mineral filament formation in actively precipitating iron-oxide environments, (3) high degrees of mineral filament bending consistent with a flexible microbial filament template, and (4) the presence of bare microbial filaments on gossan rocks. Individual HFO filaments are below the resolution of the Mars Curiosity and Mars 2020 rover cameras, but sinuous filaments forming macroscopic matlike textures are resolvable. If present on Mars, available cameras may resolve these features identified as similar to terrestrial HFO filaments and allow subsequent evaluation for their biogenicity by synthesizing geochemical, mineralogical, and morphological analyses. Sinuous

Development and manufacture of ultra-fine NbTi filament wires at ALSTHOM

International Nuclear Information System (INIS)

Hoang, G.K.; Laumond, Y.; Sabrie, J.L.; Dubots, P.

1986-01-01

Ultra-fine NbTi filament wires have been developed and manufactured by ALSTHOM. It is now possible to produce industrial copper -copper-nickel matrix wires with 0.6 mu m NbTi filaments for use in 50 / 60 Hz machines. Smaller filaments with diameters down to 0.08 mu m have been obtained with 254 100 filament wire samples. Studies are now being carried out on copper matrix conductors to reduce the filament diameter. The first results show that it is possible to obtain submicron filaments even in copper matrix wires

The Weak Lensing Masses of Filaments between Luminous Red Galaxies

Science.gov (United States)

Epps, Seth D.; Hudson, Michael J.

2017-07-01

In the standard model of non-linear structure formation, a cosmic web of dark-matter-dominated filaments connects dark matter haloes. In this paper, we stack the weak lensing signal of an ensemble of filaments between groups and clusters of galaxies. Specifically, we detect the weak lensing signal, using CFHTLenS galaxy ellipticities, from stacked filaments between Sloan Digital Sky Survey (SDSS)-III/Baryon Oscillation Spectroscopic Survey luminous red galaxies (LRGs). As a control, we compare the physical LRG pairs with projected LRG pairs that are more widely separated in redshift space. We detect the excess filament mass density in the projected pairs at the 5σ level, finding a mass of (1.6 ± 0.3) × 1013 M⊙ for a stacked filament region 7.1 h-1 Mpc long and 2.5 h-1 Mpc wide. This filament signal is compared with a model based on the three-point galaxy-galaxy-convergence correlation function, as developed in Clampitt et al., yielding reasonable agreement.

Heterocyst placement strategies to maximize the growth of cyanobacterial filaments

International Nuclear Information System (INIS)

Brown, Aidan I; Rutenberg, Andrew D

2012-01-01

Under conditions of limited fixed-nitrogen, some filamentous cyanobacteria develop a regular pattern of heterocyst cells that fix nitrogen for the remaining vegetative cells. We examine three different heterocyst placement strategies by quantitatively modelling filament growth while varying both external fixed-nitrogen and leakage from the filament. We find that there is an optimum heterocyst frequency which maximizes the growth rate of the filament; the optimum frequency decreases as the external fixed-nitrogen concentration increases but increases as the leakage increases. In the presence of leakage, filaments implementing a local heterocyst placement strategy grow significantly faster than filaments implementing random heterocyst placement strategies. With no extracellular fixed-nitrogen, consistent with recent experimental studies of Anabaena sp. PCC 7120, the modelled heterocyst spacing distribution using our local heterocyst placement strategy is qualitatively similar to experimentally observed patterns. As external fixed-nitrogen is increased, the spacing distribution for our local placement strategy retains the same shape, while the average spacing between heterocysts continuously increases. (paper)

Rapid Formation and Disappearance of a Filament Barb

Science.gov (United States)

Joshi, Anand D.; Srivastava, Nandita; Mathew, Shibu K.; Martin, Sara F.

2013-11-01

We present observations of an activated quiescent filament obtained in Hα from the high-resolution Dutch Open Telescope (DOT) on 20 August 2010. The filament developed a barb in 10 min, which disappeared within the next 35 min. A data set from the DOT spanning 2 h was used to analyse this event. Line-of-sight velocity maps were constructed from the Doppler images, which reveal flows in filament spine during this period. Photospheric magnetograms were used from the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) to determine the changes in magnetic flux in the region surrounding the barb location. The analysis shows flows in the filament spine towards the barb location preceding its formation, and flows in the barb towards the spine during its disappearance. Magnetograms reveal patches of minority polarity flux close to the end of the barb at its greatest elongation. The flows in the spine and barbs are along numerous threads that compose these typical filament structures. The flows are consistent with field-aligned threads and demonstrate that the replacement time of the mass in barbs, and by inference, in the spine is very rapid.

Morphological indictors of the chirality of solar filaments

Science.gov (United States)

Filippov, B. P.

2017-10-01

There is no doubt that the structural features of filaments reflect properties of their magnetic fields, such as chirality and helicity. However, the interpretation of some morphological features can lead to incorrect conclusions when the observing time is limited and the spatial resolution is insufficiently high. In spite of the relative constancy of their overall shapes, filaments are dynamical formations with inhomogeneities moving along the threads making them up. Therefore, it is possible to observe material concentrated not only in magnetic traps, but also along curved arcs. Difficulties often arise in determining the chirality of filaments with anomalous "barbs"; i.e., those whose jagged side is located on the opposite side of the axis compared to most ("normal") filaments. A simple model is used to show that anomalous barbs can exist in an ordinary magnetic flux rope, with the threads of its fine structure oriented nearly perpendicular to its length. A careful analysis of images with the maximum available spatial resolution and with information about temporal dynamics, together with comparisons with observations in various spectral lines, can enable a correct determination of the chirality of filaments.

Validation of the Amsterdam Dynamic Facial Expression Set – Bath Intensity Variations (ADFES-BIV): A Set of Videos Expressing Low, Intermediate, and High Intensity Emotions

Science.gov (United States)

Wingenbach, Tanja S. H.

2016-01-01

Most of the existing sets of facial expressions of emotion contain static photographs. While increasing demand for stimuli with enhanced ecological validity in facial emotion recognition research has led to the development of video stimuli, these typically involve full-blown (apex) expressions. However, variations of intensity in emotional facial expressions occur in real life social interactions, with low intensity expressions of emotions frequently occurring. The current study therefore developed and validated a set of video stimuli portraying three levels of intensity of emotional expressions, from low to high intensity. The videos were adapted from the Amsterdam Dynamic Facial Expression Set (ADFES) and termed the Bath Intensity Variations (ADFES-BIV). A healthy sample of 92 people recruited from the University of Bath community (41 male, 51 female) completed a facial emotion recognition task including expressions of 6 basic emotions (anger, happiness, disgust, fear, surprise, sadness) and 3 complex emotions (contempt, embarrassment, pride) that were expressed at three different intensities of expression and neutral. Accuracy scores (raw and unbiased (Hu) hit rates) were calculated, as well as response times. Accuracy rates above chance level of responding were found for all emotion categories, producing an overall raw hit rate of 69% for the ADFES-BIV. The three intensity levels were validated as distinct categories, with higher accuracies and faster responses to high intensity expressions than intermediate intensity expressions, which had higher accuracies and faster responses than low intensity expressions. To further validate the intensities, a second study with standardised display times was conducted replicating this pattern. The ADFES-BIV has greater ecological validity than many other emotion stimulus sets and allows for versatile applications in emotion research. It can be retrieved free of charge for research purposes from the corresponding author

Failure and nonfailure of fluid filaments in extension

DEFF Research Database (Denmark)

Hassager, Ole; Kolte, Mette Irene; Renardy, Michael

1998-01-01

The phenomenon of ductile failure of Newtonian and viscoelastic fluid filaments without surface tension is studied by a 2D finite element method and by ID non-linear analysis. The viscoelastic fluids are described by single integral constitutive equations. The main conclusions are: (1) Newtonian...... fluid filaments do not exhibit ductile failure without surface tension; (2) some viscoelastic fluids form stable filaments while other fluids exhibit ductile failure as a result of an elastic instability; (3) for large Deborah numbers, the Considere condition may be used to predict the Hencky strain...

Dynamic Regulation of Sarcomeric Actin Filaments in Striated Muscle

OpenAIRE

Ono, Shoichiro

2010-01-01

In striated muscle, the actin cytoskeleton is differentiated into myofibrils. Actin and myosin filaments are organized in sarcomeres and specialized for producing contractile forces. Regular arrangement of actin filaments with uniform length and polarity is critical for the contractile function. However, the mechanisms of assembly and maintenance of sarcomeric actin filaments in striated muscle are not completely understood. Live imaging of actin in striated muscle has revealed that actin sub...

Control of multiple filamentation in air

Science.gov (United States)

Fibich, Gadi; Eisenmann, Shmuel; Ilan, Boaz; Zigler, Arie

2004-08-01

In this Letter we provide what is believed to be the first experimental evidence of suppression of the number of filaments for high-intensity laser pulses propagating in air by beam astigmatism. We also show that the number, pattern, and spatial stability of the filaments can be controlled by varying the angle that a focusing lens makes with the axial direction of propagation. This new methodology can be useful for applications involving atmospheric propagation, such as remote sensing.

Fully filamentized HTS coated conductor via striation and selective electroplating

Energy Technology Data Exchange (ETDEWEB)

Kesgin, Ibrahim; Majkic, Goran [Department of Mechanical Engineering and Texas Center for Superconductivity, University of Houston, Houston, TX 77204 (United States); Selvamanickam, Venkat, E-mail: selva@uh.edu [Department of Mechanical Engineering and Texas Center for Superconductivity, University of Houston, Houston, TX 77204 (United States)

2013-03-15

Highlights: ► Fully-filamentized coated conductor with 13-fold reduction in ac losses. ► Selective electroplating for filamentization of thick copper stabilizer. ► A twofold decrease in ac loss by filamentization of copper stabilizer. ► Absence of appreciable coupling loss contribution from electroplating. -- Abstract: A simple, cost-effective method involving top-down mechanical scribing, oxidation and bottom-up electroplating has been successfully developed to fabricate fully filamentized HTS coated conductors. The copper stabilizer layer is selectively electroplated on the superconducting filaments while the striations remain copper-free due to the formation of a resistive oxide layer in between filaments by oxidation of the striated grooves at elevated temperature in oxygen atmosphere. Magnetization AC loss measurements, performed in a frequency range of 45–500 Hz at 77 K, confirmed the expected N-fold reduction in AC loss of the filamentized tapes with no significant degradation in critical current beyond that due to the material removal from the striations (N – number of filaments). A considerable reduction in coupling AC loss was observed after high temperature annealing/oxidation of the striated tapes. Furthermore, a significant reduction in eddy current loss was achieved with selective copper electroplating, as evidenced by analyzing the field and frequency dependence of magnetization AC loss, as well as by comparing the AC loss performance of striated samples to that of non-striated samples after electroplating of copper stabilizer.

Fully filamentized HTS coated conductor via striation and selective electroplating

International Nuclear Information System (INIS)

Kesgin, Ibrahim; Majkic, Goran; Selvamanickam, Venkat

2013-01-01

Highlights: ► Fully-filamentized coated conductor with 13-fold reduction in ac losses. ► Selective electroplating for filamentization of thick copper stabilizer. ► A twofold decrease in ac loss by filamentization of copper stabilizer. ► Absence of appreciable coupling loss contribution from electroplating. -- Abstract: A simple, cost-effective method involving top-down mechanical scribing, oxidation and bottom-up electroplating has been successfully developed to fabricate fully filamentized HTS coated conductors. The copper stabilizer layer is selectively electroplated on the superconducting filaments while the striations remain copper-free due to the formation of a resistive oxide layer in between filaments by oxidation of the striated grooves at elevated temperature in oxygen atmosphere. Magnetization AC loss measurements, performed in a frequency range of 45–500 Hz at 77 K, confirmed the expected N-fold reduction in AC loss of the filamentized tapes with no significant degradation in critical current beyond that due to the material removal from the striations (N – number of filaments). A considerable reduction in coupling AC loss was observed after high temperature annealing/oxidation of the striated tapes. Furthermore, a significant reduction in eddy current loss was achieved with selective copper electroplating, as evidenced by analyzing the field and frequency dependence of magnetization AC loss, as well as by comparing the AC loss performance of striated samples to that of non-striated samples after electroplating of copper stabilizer

Solo and keratin filaments regulate epithelial tubule morphology.

Science.gov (United States)

Nishimura, Ryosuke; Kato, Kagayaki; Fujiwara, Sachiko; Ohashi, Kazumasa; Mizuno, Kensaku

2018-04-28

Epithelial tubules, consisting of the epithelial cell sheet with a central lumen, are the basic structure of many organs. Mechanical forces play an important role in epithelial tubulogenesis; however, little is known about the mechanisms controlling the mechanical forces during epithelial tubule morphogenesis. Solo (also known as ARHGEF40) is a RhoA-targeting guanine-nucleotide exchange factor that is involved in mechanical force-induced RhoA activation and stress fiber formation. Solo binds to keratin-8/keratin-18 (K8/K18) filaments, and this interaction plays a crucial role in mechanotransduction. In this study, we examined the roles of Solo and K8/K18 filaments in epithelial tubulogenesis using MDCK cells cultured in 3D collagen gels. Knockdown of either Solo or K18 resulted in rounder tubules with increased lumen size, indicating that Solo and K8/K18 filaments play critical roles in forming the elongated morphology of epithelial tubules. Moreover, knockdown of Solo or K18 decreased the level of diphosphorylated myosin light chain (a marker of contractile force) at the luminal and outer surfaces of tubules, suggesting that Solo and K8/K18 filaments are involved in the generation of the myosin II-mediated contractile force during epithelial tubule morphogenesis. In addition, K18 filaments were normally oriented along the long axis of the tubule, but knockdown of Solo perturbed their orientation. These results suggest that Solo plays crucial roles in forming the elongated morphology of epithelial tubules and in regulating myosin II activity and K18 filament organization during epithelial tubule formation.

Structures Of Magnetically-Supported Filaments And Their Appearance In The Linear Polarization

Science.gov (United States)

Tomisaka, Kohji

2017-10-01

Dust thermal emissions observed with Herschel have revealed that interstellar molecular clouds consist of many filaments. Polarization observation of interstellar extinctions in the optical and near IR wavelengths shows that the dense filaments are extending perpendicular to the interstellar magnetic field. Magnetohydrostatic structures of such filaments are studied. It is well known that a hydrostatic filament without magnetic field has a maximum line mass of ¥lambda_max=2c_s^2/G (c_s:the isothermal sound speed and G: the gravitational constant). On the other hand, the magnetically-supported maximum line mass increases in proportion to the magnetic flux per unit length threading the filament (¥phi), as ¥lambda_max 2c_s^2/G + ¥phi/(2¥pi G^1/2). Comparison is made with 3D clouds. Stability of these magnetized filaments is studied using time-dependent 3D MHD simulations to discuss star formation in the filaments. Polarization pattern expected for the magnetically subcritical filaments is calculated. The distribution function of the angle between B-field and the axis of the filament, which is obtained with Planck Satellite, is compared with this mock observation.

Post-filament self-trapping of ultrashort laser pulses.

Science.gov (United States)

Mitrofanov, A V; Voronin, A A; Sidorov-Biryukov, D A; Andriukaitis, G; Flöry, T; Pugžlys, A; Fedotov, A B; Mikhailova, J M; Panchenko, V Ya; Baltuška, A; Zheltikov, A M

2014-08-15

Laser filamentation is understood to be self-channeling of intense ultrashort laser pulses achieved when the self-focusing because of the Kerr nonlinearity is balanced by ionization-induced defocusing. Here, we show that, right behind the ionized region of a laser filament, ultrashort laser pulses can couple into a much longer light channel, where a stable self-guiding spatial mode is sustained by the saturable self-focusing nonlinearity. In the limiting regime of negligibly low ionization, this post-filamentation beam dynamics converges to a large-scale beam self-trapping scenario known since the pioneering work on saturable self-focusing nonlinearities.

Design of the klystron filament power supply control system for EAST LHCD

Energy Technology Data Exchange (ETDEWEB)

Wu, Zege; Wang, Mao; Hu, Huaichuan; Ma, Wendong; Zhou, Taian; Zhou, Faxin; Liu, Fukun; Shan, Jiafang [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

2016-09-15

A filament is a critical component of the klystron used to heat the cathode. There are totally 44 klystrons in experimental advanced superconducting tokamak (EAST) lower hybrid current drive (LHCD) systems. All klystron filaments are powered by AC power suppliers through isolated transformers. In order to achieve better klystron preheat, a klystron filament power supply control system is designed to obtain the automatic control of all filament power suppliers. Klystron filament current is measured by PLC and the interlock between filament current and klystron high voltage system is also implemented. This design has already been deployed in two LHCD systems and proves feasible completely.

Spatial correlation of conductive filaments for multiple switching cycles in CBRAM

KAUST Repository

Pey, K. L.

2014-06-01

Conducting bridge random access memory (CBRAM) is one of the potential technologies being considered for replacement of Flash memory for non-volatile data storage. CBRAM devices operate on the principle of nucleation and rupture of metallic filaments. One key concern for commercializing this technology is the question of variability which could arise due to nucleation of multiple filaments across the device at spatially different locations. The spatial spread of the filament location may cause long tails at the low and high percentile regions for the switching parameter distribution as the new filament that nucleates may have a completely different shape and size. It is therefore essential to probe whether switching in CBRAM occurs every time at the same filament location or whether there are other new filaments that could nucleate during repeated cycling with some spatial correlation (if any) to the original filament. To investigate this issue, we make use of a metal-insulator-semiconductor (M-I-S) transistor test structure with Ni as the top electrode and HfOx/SiOx as the dielectric stack. In-situ stressing using a nano-tip on the M-I-S stack is performed and the filament is imaged in real-time using a high resolution transmission electron microscope (TEM). We also extract the location of the filament (LFIL) along the channel of the transistor after the nucleation stage using the weighted proportion of the source and drain currents. © 2014 IEEE.

Two Types of Long-duration Quasi-static Evolution of Solar Filaments

Science.gov (United States)

Xing, C.; Li, H. C.; Jiang, B.; Cheng, X.; Ding, M. D.

2018-04-01

In this Letter, we investigate the long-duration quasi-static evolution of 12 pre-eruptive filaments (four active region (AR) and eight quiescent filaments), mainly focusing on the evolution of the filament height in 3D and the decay index of the background magnetic field. The filament height in 3D is derived through two-perspective observations of Solar Dynamics Observatory (SDO) and Solar TErrestrial RElations Observatory (STEREO). The coronal magnetic field is reconstructed using the potential field source surface model. A new finding is that the filaments we studied show two types of long-duration evolution: one type comprises a long-duration static phase and a short, slow rise phase with a duration of less than 12 hr and a speed of 0.1–0.7 km s‑1, while the other one only presents a slow rise phase but with an extremely long duration of more than 60 hr and a smaller speed of 0.01–0.2 km s‑1. At the moment approaching the eruption, the decay index of the background magnetic field at the filament height is similar for both AR and quiescent filaments. The average value and upper limit are ∼0.9 and ∼1.4, close to the critical index of torus instability. Moreover, the filament height and background magnetic field strength are also found to be linearly and exponentially related with the filament length, respectively.

A hot X-ray filament associated with A3017 galaxy cluster

Science.gov (United States)

Parekh, V.; Durret, F.; Padmanabh, P.; Pandge, M. B.

2017-09-01

Recent simulations and observations have shown large-scale filaments in the cosmic web connecting nodes, with accreting materials (baryonic and dark matter) flowing through them. Current high-sensitivity observations also show that the propagation of shocks through filaments can heat them up and make filaments visible between two or more galaxy clusters or around massive clusters, based on optical and/or X-ray observations. We are reporting here the special case of the cluster A3017 associated with a hot filament. The temperature of the filament is 3.4^{-0.77}_{+1.30} keV and its length is ∼1 Mpc. We have analysed its archival Chandra data and report various properties. We also analysed GMRT 235/610 MHz radio data. Radio observations have revealed symmetric two-sided lobes that fill cavities in the A3017 cluster core region, associated with central active galactic nucleus. In the radio map, we also noticed a peculiar linear vertical radio structure in the X-ray filament region which might be associated with a cosmic filament shock. This radio structure could be a radio phoenix or old plasma where an old relativistic population is re-accelerated by shock propagation. Finally, we put an upper limit on the radio luminosity of the filament region.

Weak-lensing detection of intracluster filaments with ground-based data

Science.gov (United States)

Maturi, Matteo; Merten, Julian

2013-11-01

According to the current standard model of cosmology, matter in the Universe arranges itself along a network of filamentary structure. These filaments connect the main nodes of this so-called "cosmic web", which are clusters of galaxies. Although its large-scale distribution is clearly characterized by numerical simulations, constraining the dark-matter content of the cosmic web in reality turns out to be difficult. The natural method of choice is gravitational lensing. However, the direct detection and mapping of the elusive filament signal is challenging and in this work we present two methods that are specifically tailored to achieve this task. A linear matched filter aims at detecting the smooth mass-component of filaments and is optimized to perform a shear decomposition that follows the anisotropic component of the lensing signal. Filaments clearly inherit this property due to their morphology. At the same time, the contamination arising from the central massive cluster is controlled in a natural way. The filament 1σ detection is of about κ ~ 0.01 - 0.005 according to the filter's template width and length, enabling the detection of structures beyond reach with other approaches. The second, complementary method seeks to detect the clumpy component of filaments. The detection is determined by the number density of subclump identifications in an area enclosing the potential filament, as was found within the observed field with the filter approach. We tested both methods against mocked observations based on realistic N-body simulations of filamentary structure and proved the feasibility of detecting filaments with ground-based data.

Electro-mechanical behaviors of composite superconducting strand with filament breakage

International Nuclear Information System (INIS)

Wang, Xu; Gao, Yuanwen; Zhou, Youhe

2016-01-01

Highlights: • The electromechanical behaviors of the superconducting (SC) strand are investigated. • A 3D FEM model for bending behaviors and electric properties of strand is developed. • The influence of breakage of filaments on the critical current of SC strand is calculated. • The impact of current transfer length on the electric properties of SC strand is discussed. - Abstract: The bending behaviors of superconducting strand with typical multi-filament twist configuration are investigated based on a three-dimensional finite element method (FEM) model, named as the Multi-filament twist model, of the strand. In this 3D FEM model, the impacts of initial thermal residual stress, filament-breakage and its evaluation are taken into accounts. The mechanical responses of the strand under bending load are studied with the factors taken into consideration one by one. The distribution of the damage of the filaments and its evolution and the movement of the neutral axis caused by it are studied and displayed in detail. Besides, taking the advantages of the Multi-filament twist model, the normalized critical current of the strand under bending load is also calculated based on the invariant temperature and field strain functions. In addition, the non-negligible influences of the pitch length of the filaments on both the mechanical behaviors and the normalized critical current are discussed. The stress-strain characteristics of the strand under tensile load and the normalized critical current of it under axial and bending loads resulting from the Multi-filament twist model show good agreement with the experimental data.

Electro-mechanical behaviors of composite superconducting strand with filament breakage

Energy Technology Data Exchange (ETDEWEB)

Wang, Xu [Key Laboratory of Mechanics on Environment and Disaster in Western China, The Ministry of Education of China, Lanzhou, Gansu 730000 (China); Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China); Gao, Yuanwen, E-mail: ywgao@lzu.edu.cn [Key Laboratory of Mechanics on Environment and Disaster in Western China, The Ministry of Education of China, Lanzhou, Gansu 730000 (China); Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China); Zhou, Youhe [Key Laboratory of Mechanics on Environment and Disaster in Western China, The Ministry of Education of China, Lanzhou, Gansu 730000 (China); Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China)

2016-10-15

Highlights: • The electromechanical behaviors of the superconducting (SC) strand are investigated. • A 3D FEM model for bending behaviors and electric properties of strand is developed. • The influence of breakage of filaments on the critical current of SC strand is calculated. • The impact of current transfer length on the electric properties of SC strand is discussed. - Abstract: The bending behaviors of superconducting strand with typical multi-filament twist configuration are investigated based on a three-dimensional finite element method (FEM) model, named as the Multi-filament twist model, of the strand. In this 3D FEM model, the impacts of initial thermal residual stress, filament-breakage and its evaluation are taken into accounts. The mechanical responses of the strand under bending load are studied with the factors taken into consideration one by one. The distribution of the damage of the filaments and its evolution and the movement of the neutral axis caused by it are studied and displayed in detail. Besides, taking the advantages of the Multi-filament twist model, the normalized critical current of the strand under bending load is also calculated based on the invariant temperature and field strain functions. In addition, the non-negligible influences of the pitch length of the filaments on both the mechanical behaviors and the normalized critical current are discussed. The stress-strain characteristics of the strand under tensile load and the normalized critical current of it under axial and bending loads resulting from the Multi-filament twist model show good agreement with the experimental data.

Mitochondrial intermediate peptidase: Expression in Escherichia coli and improvement of its enzymatic activity detection with FRET substrates

International Nuclear Information System (INIS)

Marcondes, Marcelo F.; Torquato, Ricardo J.S.; Assis, Diego M.; Juliano, Maria A.; Hayashi, Mirian A.F.; Oliveira, Vitor

2010-01-01

In the present study, soluble, functionally-active, recombinant human mitochondrial intermediate peptidase (hMIP), a mitochondrial metalloendoprotease, was expressed in a prokaryotic system. The hMIP fusion protein, with a poly-His-tag (6x His), was obtained by cloning the coding region of hMIP cDNA into the pET-28a expression vector, which was then used to transform Escherichia coli BL21 (DE3) pLysS. After isolation and purification of the fusion protein by affinity chromatography using Ni-Sepharose resin, the protein was purified further using ion exchange chromatography with a Hi-trap resource Q column. The recombinant hMIP was characterized by Western blotting using three distinct antibodies, circular dichroism, and enzymatic assays that used the first FRET substrates developed for MIP and a series of protease inhibitors. The successful expression of enzymatically-active hMIP in addition to the FRET substrates will contribute greatly to the determination of substrate specificity of this protease and to the development of specific inhibitors that are essential for a better understanding of the role of this protease in mitochondrial functioning.

Magnetization Modeling of Twisted Superconducting Filaments

CERN Document Server

Satiramatekul, T; Devred, Arnaud; Leroy, Daniel

2007-01-01

This paper presents a new Finite Element numerical method to analyze the coupling between twisted filaments in a superconducting multifilament composite wire. To avoid the large number of elements required by a 3D code, the proposed method makes use of the energy balance principle in a 2D code. The relationship between superconductor critical current density and local magnetic flux density is implemented in the program for the Bean and modified Kim models. The modeled wire is made up of six filaments twisted together and embedded in a lowresistivity matrix. Computations of magnetization cycle and of the electric field pattern have been performed for various twist pitch values in the case of a pure copper matrix. The results confirm that the maximum magnetization depends on the matrix conductivity, the superconductor critical current density, the applied field frequency, and the filament twist pitch. The simulations also lead to a practical criterion for wire design that can be used to assess whether or not th...

Radiation-induced grafting of acrylic acid onto polyethylene filaments

International Nuclear Information System (INIS)

Kaji, K.; Sakurada, I.; Okada, T.

1981-01-01

Radiation-induced grafting of acrylic acid onto high density polyethylene (PE) filaments was carried out in order to raise softening temperature and impart flame retardance and hydrophilic properties. Mutual γ-irradiation method was employed for the grafting in a mixture of acrylic acid (AA), ethylene dichloride and water containing a small amount of ferrous ammonium sulfate. The rate of grafting was very low at room temperature. On the other hand, large percent grafts were obtained when the grafting was performed at an elevated temperature. Activation energy for the initial rate of grafting was found to be 17 kcal/mol between 20 and 60 0 C and 10 kcal/ mol between 60 and 80 0 C. Original PE filament begins to shrink at 70 0 C, shows maximum shrinkage of 50% at 130 0 C and then breaks off at 136 0 C. When a 34% AA graft is converted to metallic salt the graft filament retains its filament form even above 300 0 C and gives maximum shrinkage of 15%. Burning tests by a wire-netting basket method indicate that graft filaments and their metallic salts do not form melting drops upon burning and are self-extinguishing. Original PE filament shows no moisture absorption; however, that of AA-grafted PE increases with increasing graft percent. (author)

Dependence of the length of solar filament threads on the magnetic configuration

International Nuclear Information System (INIS)

Zhou Yu-Hao; Chen Peng-Fei; Fang Cheng; Zhang Qing-Min

2014-01-01

High-resolution Hα observations indicate that filaments consist of an assembly of thin threads. In quiescent filaments, the threads are generally short, whereas in active region filaments, the threads are generally long. In order to explain these observational features, we performed one-dimensional radiative hydrodynamic simulations of filament formation along a dipped magnetic flux tube in the framework of the chromospheric evaporation-coronal condensation model. The geometry of a dipped magnetic flux tube is characterized by three parameters, i.e., the depth (D), the half-width (w) and the altitude (h) of the magnetic dip. A survey of the parameters in numerical simulations shows that when allowing the filament thread to grow in 5 days, the maximum length (L th ) of the filament thread increases linearly with w, and decreases linearly with D and h. The dependence is fitted into a linear function L th = 0.84w − 0.88D − 2.78h+17.31(Mm). Such a relation can qualitatively explain why quiescent filaments have shorter threads and active region filaments have longer threads

Method for simultaneously coating a plurality of filaments

Science.gov (United States)

Miller, P.A.; Pochan, P.D.; Siegal, M.P.; Dominguez, F.

1995-07-11

Methods and apparatuses are disclosed for coating materials, and the products and compositions produced thereby. Substances, such as diamond or diamond-like carbon, are deposited onto materials, such as a filament or a plurality of filaments simultaneously, using one or more cylindrical, inductively coupled, resonator plasma reactors. 3 figs.

Architecture and fine structure of gill filaments in the brown mussel, perna perna

CSIR Research Space (South Africa)

Gregory, MA

1996-10-01

Full Text Available attention was paid to filament architecture, enervation of filaments, number and type of cells populating filament epithelia and variations in epithelial cell morphotogy and cilia ultra structure. Filament shape was maintained by thickened chitin...

THE DISAPPEARING SOLAR FILAMENT OF 2003 JUNE 11: A THREE-BODY PROBLEM

Energy Technology Data Exchange (ETDEWEB)

Balasubramaniam, K. S. [Space Vehicles Directorate, Air Force Research Laboratory, Kirtland AFB, NM 87117 (United States); Pevtsov, A. A. [National Solar Observatory, Sunspot, NM 88349 (United States); Cliver, E. W. [Space Vehicles Directorate, Air Force Research Laboratory, Sunspot, NM 88349 (United States); Martin, S. F.; Panasenco, O. [Helio Research, La Crescenta, CA 91214 (United States)

2011-12-20

The eruption of a large quiescent filament on 2003 June 11 was preceded by the birth of a nearby active region-a common scenario. In this case, however, the filament lay near a pre-existing active region and the new active region did not destabilize the filament by direct magnetic connection. Instead it appears to have done so indirectly via magnetic coupling with the established region. Restructuring between the perturbed fields of the old region and the filament then weakened the arcade overlying the midpoint of filament, where the eruption originated. The inferred rate ({approx}11 Degree-Sign day{sup -1}) at which the magnetic disturbance propagates from the mature region to destabilize the filament is larger than the mean speed ({approx}5 Masculine-Ordinal-Indicator -6 Degree-Sign day{sup -1}) but still within the scatter obtained for Bruzek's empirical relationship between the distance from a newly formed active region to a quiescent filament and the time from active region appearance to filament disappearance. The higher propagation speed in the 2003 June 11 case may be due to the 'broadside' (versus 'end-on') angle of attack of the (effective) new flux to the coronal magnetic fields overlying a central section of the axis of the filament.

THE DISAPPEARING SOLAR FILAMENT OF 2003 JUNE 11: A THREE-BODY PROBLEM

International Nuclear Information System (INIS)

Balasubramaniam, K. S.; Pevtsov, A. A.; Cliver, E. W.; Martin, S. F.; Panasenco, O.

2011-01-01

The eruption of a large quiescent filament on 2003 June 11 was preceded by the birth of a nearby active region—a common scenario. In this case, however, the filament lay near a pre-existing active region and the new active region did not destabilize the filament by direct magnetic connection. Instead it appears to have done so indirectly via magnetic coupling with the established region. Restructuring between the perturbed fields of the old region and the filament then weakened the arcade overlying the midpoint of filament, where the eruption originated. The inferred rate (∼11° day –1 ) at which the magnetic disturbance propagates from the mature region to destabilize the filament is larger than the mean speed (∼5º-6° day –1 ) but still within the scatter obtained for Bruzek's empirical relationship between the distance from a newly formed active region to a quiescent filament and the time from active region appearance to filament disappearance. The higher propagation speed in the 2003 June 11 case may be due to the 'broadside' (versus 'end-on') angle of attack of the (effective) new flux to the coronal magnetic fields overlying a central section of the axis of the filament.

How capping protein enhances actin filament growth and nucleation on biomimetic beads.

Science.gov (United States)

Wang, Ruizhe; Carlsson, Anders E

2015-11-25

Capping protein (CP), which caps the growing ends of actin filaments, accelerates actin-based motility. Recent experiments on biomimetic beads have shown that CP also enhances the rate of actin filament nucleation. Proposed explanations for these phenomena include (i) the actin funneling hypothesis (AFH), in which the presence of CP increases the free-actin concentration, and (ii) the monomer gating model, in which CP binding to actin filament barbed ends makes more monomers available for filament nucleation. To establish how CP increases the rates of filament elongation and nucleation on biomimetic beads, we perform a quantitative modeling analysis of actin polymerization, using rate equations that include actin filament nucleation, polymerization and capping, as modified by monomer depletion near the surface of the bead. With one adjustable parameter, our simulation results match previously measured time courses of polymerized actin and filament number. The results support a version of the AFH where CP increases the local actin monomer concentration at the bead surface, but leaves the global free-actin concentration nearly constant. Because the rate of filament nucleation increases with the monomer concentration, the increased local monomer concentration enhances actin filament nucleation. We derive a closed-form formula for the characteristic CP concentration where the local free-actin concentration reaches half the bulk value, and find it to be comparable to the global Arp2/3 complex concentration. We also propose an experimental protocol for distinguishing branching nucleation of filaments from spontaneous nucleation.

Interfering with the wake of cylinder by flexible filaments

Science.gov (United States)

Pinelli, Alfredo; Omidyeganeh, Mohammad

2015-11-01

This work is the very first attempt to understand and optimize the configuration of flexible filaments placed on the lee side of a bluff body to manipulate flow transitions and bifurcations. It is found that the presence of a sparse set of flexible filaments on the lee side of a cylinder can interfere with the 2D-3D transition process resulting in elongation of recirculation bubble, inhibition of higher order unstable modes, and narrowing the global energy content about a particular shedding frequency. Filaments become effective when spacing between them is smaller than the dominant unstable mode at each particular Reynolds number, i.e. A and B modes. In another study, by a particular arrangement the reconfigured filaments can reduce pressure fluctuations in the wake and drop lift flluctuations significantly (~= 80 %).

Zebrafish cardiac muscle thick filaments: isolation technique and three-dimensional structure.

Science.gov (United States)

González-Solá, Maryví; Al-Khayat, Hind A; Behra, Martine; Kensler, Robert W

2014-04-15

To understand how mutations in thick filament proteins such as cardiac myosin binding protein-C or titin, cause familial hypertrophic cardiomyopathies, it is important to determine the structure of the cardiac thick filament. Techniques for the genetic manipulation of the zebrafish are well established and it has become a major model for the study of the cardiovascular system. Our goal is to develop zebrafish as an alternative system to the mammalian heart model for the study of the structure of the cardiac thick filaments and the proteins that form it. We have successfully isolated thick filaments from zebrafish cardiac muscle, using a procedure similar to those for mammalian heart, and analyzed their structure by negative-staining and electron microscopy. The isolated filaments appear well ordered with the characteristic 42.9 nm quasi-helical repeat of the myosin heads expected from x-ray diffraction. We have performed single particle image analysis on the collected electron microscopy images for the C-zone region of these filaments and obtained a three-dimensional reconstruction at 3.5 nm resolution. This reconstruction reveals structure similar to the mammalian thick filament, and demonstrates that zebrafish may provide a useful model for the study of the changes in the cardiac thick filament associated with disease processes. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

NGVLA Observations of Dense Gas Filaments in Star-Forming Regions

Science.gov (United States)

Di Francesco, James; Chen, Mike; Keown, Jared; GAS Team, KEYSTONE Team

2018-01-01

Recent observations of continuum emission from nearby star-forming regions with Herschel and JCMT have revealed that filaments are ubiquitous structures within molecular clouds. Such filaments appear to be intimately connected to star formation, with those having column densities of AV > 8 hosting the majority of prestellar cores and young protostars in clouds. Indeed, this “threshold” can be explained simply as the result of supercritical cylinder fragmentation. How specifically star-forming filaments form in molecular clouds, however, remains unclear, though gravity and turbulence are likely involved. Observations of their kinematics are needed to understand how mass flows both onto and through these filaments. We show here results from two recent surveys, the Green Bank Ammonia Survey (GAS) and the K-band Examinations of Young Stellar Object Natal Environments (KEYSTONE) that have used the Green Bank Telescope’s K-band Focal Plane Array instrument to map NH3 (1,1) emission from dense gas in nearby star-forming regions. Data from both surveys show that NH3 emission traces extremely well the high column density gas across these star-forming regions. In particular, the GAS results for NGC 1333 show NH3-based velocity gradients either predominantly parallel or perpendicular to the filament spines. Though the GAS and KEYSTONE data are vital for probing filaments, higher resolutions than possible with the GBT alone are needed to examine the kinematic patterns on the 0.1-pc scales of star-forming cores within filaments. We describe how the Next Generation Very Large Array (NGVLA) will uniquely provide the key wide-field data of high sensitivity needed to explore how ambient gas in molecular clouds forms filaments that evolve toward star formation.

Filament winding technique, experiment and simulation analysis on tubular structure

Science.gov (United States)

Quanjin, Ma; Rejab, M. R. M.; Kaige, Jiang; Idris, M. S.; Harith, M. N.

2018-04-01

Filament winding process has emerged as one of the potential composite fabrication processes with lower costs. Filament wound products involve classic axisymmetric parts (pipes, rings, driveshafts, high-pressure vessels and storage tanks), non-axisymmetric parts (prismatic nonround sections and pipe fittings). Based on the 3-axis filament winding machine has been designed with the inexpensive control system, it is completely necessary to make a relative comparison between experiment and simulation on tubular structure. In this technical paper, the aim of this paper is to perform a dry winding experiment using the 3-axis filament winding machine and simulate winding process on the tubular structure using CADWIND software with 30°, 45°, 60° winding angle. The main result indicates that the 3-axis filament winding machine can produce tubular structure with high winding pattern performance with different winding angle. This developed 3-axis winding machine still has weakness compared to CAWIND software simulation results with high axes winding machine about winding pattern, turnaround impact, process error, thickness, friction impact etc. In conclusion, the 3-axis filament winding machine improvements and recommendations come up with its comparison results, which can intuitively understand its limitations and characteristics.

Interaction of Two Active Region Filaments Observed by NVST and SDO

Energy Technology Data Exchange (ETDEWEB)

Yang, Liheng; Yan, Xiaoli; Xue, Zhike; Xiang, Yongyuan [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650216 (China); Li, Ting, E-mail: yangliheng@ynao.ac.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2017-04-01

Using high spatial and temporal resolution H α data from the New Vacuum Solar Telescope (NVST) and simultaneous observations from the Solar Dynamics Observatory , we present the rare event of the interaction between two filaments (F1 and F2) in AR 11967 on 2014 January 31. The adjacent two filaments were almost perpendicular to each other. Their interaction was driven by the movement of F1 and started when the two filaments collided with each other. During the interaction, the threads of F1 continuously slipped from the northeast to the southwest, and were accompanied by the brightenings at the junction of two filaments and the northeast footpoint of F2. Part of F1 and the main body of F2 became invisible in H α wavelength due to the heating and the motion of F2. At the same time, bright material initiated from the junction of two filaments were observed to move along F1. The magnetic connectivities of F1 were found to be changed after their interaction. These observations suggest that magnetic reconnection was involved in the interaction of two filaments and resulted in the eruption of one filament.

Self-modulation and filamentation of electromagnetic waves in a plasma

International Nuclear Information System (INIS)

Bingham, R.; Lashmore-Davies, C.N.

1976-01-01

Self-modulation and filamentation of an electromagnetic wave is considered as a problem of the non-linear interaction between electromagnetic and ion waves. A new electro-magnetic modulational instability is obtained, whose threshold is the same as that of the oscillating two-stream instability. A simple geometrical model is given of filamentation when the non-linearity is due to the ponderomotive force. The relationship between the filamentation and electromagnetic modulational instabilities and other parametric instabilities is considered. In particular, it is shown that both electromagnetic modulational and filamentation instabilities can occur at the critical density where they have the same threshold as the modulational instability of a Langmuir wave. Finally, a conservation relation (a generalization of the Manley-Rowe relation) for the wave action density is obtained for the filamentation instability. This shows clearly that this instability results from a four wave interaction. (author)

All Hormone-Producing Cell Types of the Pituitary Intermediate and Anterior Lobes Derive From Prop1-Expressing Progenitors.

Science.gov (United States)

Davis, Shannon W; Keisler, Jessica L; Pérez-Millán, María I; Schade, Vanessa; Camper, Sally A

2016-04-01

Mutations in PROP1, the most common known cause of combined pituitary hormone deficiency in humans, can result in the progressive loss of all hormones of the pituitary anterior lobe. In mice, Prop1 mutations result in the failure to initiate transcription of Pou1f1 (also known as Pit1) and lack somatotropins, lactotropins, and thyrotropins. The basis for this species difference is unknown. We hypothesized that Prop1 is expressed in a progenitor cell that can develop into all anterior lobe cell types, and not just the somatotropes, thyrotropes, and lactotropes, which are collectively known as the PIT1 lineage. To test this idea, we produced a transgenic Prop1-cre mouse line and conducted lineage-tracing experiments of Prop1-expressing cells. The results reveal that all hormone-secreting cell types of both the anterior and intermediate lobes are descended from Prop1-expressing progenitors. The Prop1-cre mice also provide a valuable genetic reagent with a unique spatial and temporal expression for generating tissue-specific gene rearrangements early in pituitary gland development. We also determined that the minimal essential sequences for reliable Prop1 expression lie within 10 kilobases of the mouse gene and demonstrated that human PROP1 can substitute functionally for mouse Prop1. These studies enhance our understanding of the pathophysiology of disease in patients with PROP1 mutations.

Additive Manufacturing of Syntactic Foams: Part 1: Development, Properties, and Recycling Potential of Filaments

Science.gov (United States)

Singh, Ashish Kumar; Patil, Balu; Hoffmann, Niklas; Saltonstall, Brooks; Doddamani, Mrityunjay; Gupta, Nikhil

2018-03-01

This work focuses on developing filaments of high-density polyethylene (HDPE) and their hollow particle-filled syntactic foams for commercial three-dimensional (3D) printers based on fused filament fabrication technology. Hollow fly-ash cenospheres were blended by 40 wt.% in a HDPE matrix to produce syntactic foam (HDPE40) filaments. Further, the recycling potential was studied by pelletizing the filaments again to extrude twice (2×) and three times (3×). The filaments were tensile tested at 10-4 s-1, 10-3 s-1, and 10-2 s-1 strain rates. HDPE40 filaments show an increasing trend in modulus and strength with the strain rate. Higher density and modulus were noticed for 2× filaments compared to 1× filaments because of the crushing of some cenospheres in the extrusion cycle. However, 2× and 3× filament densities are nearly the same, showing potential for recycling them. The filaments show better properties than the same materials processed by conventional injection molding. Micro-CT scans show a uniform dispersion of cenospheres in all filaments.

Filament stretching rheometer: inertia compensation revisited

DEFF Research Database (Denmark)

Szabo, Peter; McKinley, Gareth H.

2003-01-01

The necessary inertia compensation used in the force balance for the filament stretching rheometer is derived for an arbitrary frame of reference. This enables the force balance to be used to extract correctly the extensional viscosity from measurements of the tensile force at either end of the e......The necessary inertia compensation used in the force balance for the filament stretching rheometer is derived for an arbitrary frame of reference. This enables the force balance to be used to extract correctly the extensional viscosity from measurements of the tensile force at either end...

Temperature dependence of filament-coupling in Bi-2223 tapes: magneto-optical study

International Nuclear Information System (INIS)

Bobyl, A.V.; Shantsev, D.V.; Galperin, Y.M.; Johansen, T.H.; Baziljevich, M.; Gaevski, M.E.

2000-01-01

Coupling through random superconducting bridges between filaments in a multifilamentary Ag-sheathed Bi 2 Sr 2 Ca 2 Cu 3 O 10+δ tape has been investigated by magneto-optical imaging at temperatures from 20 K up to T c . Magnetic flux distributions have been measured on the surface of an intact tape in the remanent state on applying a strong perpendicular magnetic field. The flux distributions observed at low temperatures reflect the arrangement of individual filaments. At high temperatures, the distribution becomes more similar to that for a uniform monocore tape, indicating that superconducting connections appear between the filaments. To discuss the relative contributions of the intra- and inter-filament currents, a simple model based on the Bean critical state was proposed and applied to analyse the temperature dependent behaviour. The inter-filament coupling, increasing with temperature, reaches at 77 K a point where the currents flowing in large inter-filament loops are roughly equal to the intra-filament currents. (author)

Evaluation of the local temperature of conductive filaments in resistive switching materials

International Nuclear Information System (INIS)

Yalon, E; Cohen, S; Gavrilov, A; Ritter, D

2012-01-01

The resistive switching effect in metal oxides and other dielectric materials is among the leading future non-volatile memory technologies. Resistive switching is widely ascribed to the formation and rupture of conductive filaments in the oxide, which are generated by temperature-enhanced nano-scale ion migration or other thermal effects. In spite of the central role of the local filament temperature on the switching effect, as well as on the conduction and reliability physics, no measurement methods of the filament temperature are yet available. In this work, we report on a method for evaluating the conducting filament temperature, using a metal–insulator–semiconductor bipolar transistor structure. The filament temperature is obtained by analyzing the thermal excitation rate of electrons from the filament Fermi level into the conduction band of a p-type semiconductor electrode. Measurements were carried out to obtain the conductive filament temperature in hafnia at varying ambient temperatures in the range of 3–300 K. Significant Joule heating of the filament was observed across the entire measured ambient temperature range. The extracted temperatures provide physical insight into the resistive switching effect. (paper)

Analysis of the role of the Aspergillus niger aminolevulinic acid synthase (hemA) gene illustrates the difference between regulation of yeast and fungal haem- and sirohaem-dependent pathways

NARCIS (Netherlands)

Franken, A.C.; Christien Lokman, B.; Ram, A.F.; Hondel, C.A. van den; Weert, S. de; Punt, P.J.

2012-01-01

To increase knowledge on haem biosynthesis in filamentous fungi like Aspergillus niger, pathway-specific gene expression in response to haem and haem intermediates was analysed. This analysis showed that iron, 5′-aminolevulinic acid (ALA) and possibly haem control haem biosynthesis mostly via

Analysis of the role of the A. niger aminolevulinic acid synthase (hemA) gene illustrates the difference between regulation of yeast and fungal heme and siroheme dependent pathways

NARCIS (Netherlands)

A.F. Ram; C.A. van den Hondel; Christien Lokman; P.J. Punt; S. de Weert; A. Franken

2012-01-01

To increase knowledge on haem biosynthesis in filamentous fungi like Aspergillus niger, pathway-specific gene expression in response to haem and haem intermediates was analysed. This analysis showed that iron, 5'-aminolevulinic acid (ALA) and possibly haem control haem biosynthesis mostly via

The Magnetic Structure of Filament Barbs

Science.gov (United States)

Chae, Jongchul; Moon, Yong-Jae; Park, Young-Deuk

2005-06-01

There is a controversy about how features protruding laterally from filaments, called barbs, are magnetically structured. On 2004 August 3, we observed a filament that had well-developed barbs. The observations were performed using the 10 inch refractor of the Big Bear Solar Observatory. A fast camera was employed to capture images at five different wavelengths of the Hα line and successively record them on the basis of frame selection. The terminating points of the barbs were clearly discernable in the Hα images without any ambiguity. The comparison of the Hα images with the magnetograms taken by SOHO MDI revealed that the termination occurred above the minor polarity inversion line dividing the magnetic elements of the major polarity and those of the minor polarity. There is also evidence that the flux cancellation proceeded on the polarity inversion line. Our results together with similar other recent observations support the idea that filament barbs are cool matter suspended in local dips of magnetic field lines, formed by magnetic reconnection in the chromosphere.

Renal cells express different forms of vimentin: the independent expression alteration of these forms is important in cell resistance to osmotic stress and apoptosis.

Directory of Open Access Journals (Sweden)

Bettina S Buchmaier

Full Text Available Osmotic stress has been shown to regulate cytoskeletal protein expression. It is generally known that vimentin is rapidly degraded during apoptosis by multiple caspases, resulting in diverse vimentin fragments. Despite the existence of the known apoptotic vimentin fragments, we demonstrated in our study the existence of different forms of vimentin VIM I, II, III, and IV with different molecular weights in various renal cell lines. Using a proteomics approach followed by western blot analyses and immunofluorescence staining, we proved the apoptosis-independent existence and differential regulation of different vimentin forms under varying conditions of osmolarity in renal cells. Similar impacts of osmotic stress were also observed on the expression of other cytoskeleton intermediate filament proteins; e.g., cytokeratin. Interestingly, 2D western blot analysis revealed that the forms of vimentin are regulated independently of each other under glucose and NaCl osmotic stress. Renal cells, adapted to high NaCl osmotic stress, express a high level of VIM IV (the form with the highest molecular weight, besides the three other forms, and exhibit higher resistance to apoptotic induction with TNF-α or staurosporin compared to the control. In contrast, renal cells that are adapted to high glucose concentration and express only the lower-molecular-weight forms VIM I and II, were more susceptible to apoptosis. Our data proved the existence of different vimentin forms, which play an important role in cell resistance to osmotic stress and are involved in cell protection against apoptosis.

Synergy analysis reveals association between insulin signaling and desmoplakin expression in palmitate treated HepG2 cells.

Directory of Open Access Journals (Sweden)

Xuewei Wang

Full Text Available The regulation of complex cellular activities in palmitate treated HepG2 cells, and the ensuing cytotoxic phenotype, involves cooperative interactions between genes. While previous approaches have largely focused on identifying individual target genes, elucidating interacting genes has thus far remained elusive. We applied the concept of information synergy to reconstruct a "gene-cooperativity" network for palmititate-induced cytotoxicity in liver cells. Our approach integrated gene expression data with metabolic profiles to select a subset of genes for network reconstruction. Subsequent analysis of the network revealed insulin signaling as the most significantly enriched pathway, and desmoplakin (DSP as its top neighbor. We determined that palmitate significantly reduces DSP expression, and treatment with insulin restores the lost expression of DSP. Insulin resistance is a common pathological feature of fatty liver and related ailments, whereas loss of DSP has been noted in liver carcinoma. Reduced DSP expression can lead to loss of cell-cell adhesion via desmosomes, and disrupt the keratin intermediate filament network. Our findings suggest that DSP expression may be perturbed by palmitate and, along with insulin resistance, may play a role in palmitate induced cytotoxicity, and serve as potential targets for further studies on non-alcoholic fatty liver disease (NAFLD.

Morphology and rheology in filamentous cultivations.

Science.gov (United States)

Wucherpfennig, T; Kiep, K A; Driouch, H; Wittmann, C; Krull, R

2010-01-01

Because of their metabolic diversity, high production capacity, secretion efficiency, and capability of carrying out posttranslational modifications, filamentous fungi are widely exploited as efficient cell factories in the production of metabolites, bioactive substances, and native or heterologous proteins, respectively. There is, however, a complex relationship between the morphology of these microorganisms, transport phenomena, the viscosity of the cultivation broth, and related productivity. The morphological characteristics vary between freely dispersed mycelia and distinct pellets of aggregated biomass, every growth form having a distinct influence on broth rheology. Hence, the advantages and disadvantages for mycelial or pellet cultivation have to be balanced out carefully. Because of the still inadequate understanding of the morphogenesis of filamentous microorganisms, fungal morphology is often a bottleneck of productivity in industrial production. To obtain an optimized production process, it is of great importance to gain a better understanding of the molecular and cell biology of these microorganisms as well as the relevant approaches in biochemical engineering. In this chapter, morphology and growth of filamentous fungi are described, with special attention given to specific problems as they arise from fungal growth forms; growth and mass transfer in fungal biopellets are discussed as an example. To emphasize the importance of the flow behavior of filamentous cultivation broths, an introduction to rheology is also given, reviewing important rheological models and recent studies concerning rheological parameters. Furthermore, current knowledge on morphology and productivity in relation to the environom is outlined in the last section of this review. Copyright 2010 Elsevier Inc. All rights reserved.

Regulation of Contraction by the Thick Filaments in Skeletal Muscle.

Science.gov (United States)

Irving, Malcolm

2017-12-19

Contraction of skeletal muscle cells is initiated by a well-known signaling pathway. An action potential in a motor nerve triggers an action potential in a muscle cell membrane, a transient increase of intracellular calcium concentration, binding of calcium to troponin in the actin-containing thin filaments, and a structural change in the thin filaments that allows myosin motors from the thick filaments to bind to actin and generate force. This calcium/thin filament mediated pathway provides the "START" signal for contraction, but it is argued that the functional response of the muscle cell, including the speed of its contraction and relaxation, adaptation to the external load, and the metabolic cost of contraction is largely determined by additional mechanisms. This review considers the role of the thick filaments in those mechanisms, and puts forward a paradigm for the control of contraction in skeletal muscle in which both the thick and thin filaments have a regulatory function. The OFF state of the thick filament is characterized by helical packing of most of the myosin head or motor domains on the thick filament surface in a conformation that makes them unavailable for actin binding or ATP hydrolysis, although a small fraction of the myosin heads are constitutively ON. The availability of the majority fraction of the myosin heads for contraction is controlled in part by the external load on the muscle, so that these heads only attach to actin and hydrolyze ATP when they are required. This phenomenon seems to be the major determinant of the well-known force-velocity relationship of muscle, and controls the metabolic cost of contraction. The regulatory state of the thick filament also seems to control the dynamics of both muscle activation and relaxation. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Developments in hot-filament metal oxide deposition (HFMOD)

International Nuclear Information System (INIS)

Durrant, Steven F.; Trasferetti, Benedito C.; Scarminio, Jair; Davanzo, Celso U.; Rouxinol, Francisco P.M.; Gelamo, Rogerio V.; Bica de Moraes, Mario A.

2008-01-01

Hot-filament metal oxide deposition (HFMOD) is a variant of conventional hot-filament chemical vapor deposition (HFCVD) recently developed in our laboratory and successfully used to obtain high-quality, uniform films of MO x , WO x and VO x . The method employs the controlled oxidation of a filament of a transition metal heated to 1000 deg. C or more in a rarefied oxygen atmosphere (typically, of about 1 Pa). Metal oxide vapor formed on the surface of the filament is transported a few centimetres to deposit on a suitable substrate. Key system parameters include the choice of filament material and diameter, the applied current and the partial pressures of oxygen in the chamber. Relatively high film deposition rates, such as 31 nm min -1 for MoO x , are obtained. The film stoichiometry depends on the exact deposition conditions. MoO x films, for example, present a mixture of MoO 2 and MoO 3 phases, as revealed by XPS. As determined by Li + intercalation using an electrochemical cell, these films also show a colouration efficiency of 19.5 cm 2 C -1 at a wavelength of 700 nm. MO x and WO x films are promising in applications involving electrochromism and characteristics of their colouring/bleaching cycles are presented. The chemical composition and structure of VO x films examined using IRRAS (infrared reflection-absorption spectroscopy), RBS (Rutherford backscattering spectrometry) and XPS (X-ray photoelectron spectrometry) are also presented

Design and Optimization of Filament Wound Composite Pressure Vessels

NARCIS (Netherlands)

Zu, L.

2012-01-01

One of the most important issues for the design of filament-wound pressure vessels reflects on the determination of the most efficient meridian profiles and related fiber architectures, leading to optimal structural performance. To better understand the design and optimization of filament-wound

PRE-ERUPTION OSCILLATIONS IN THIN AND LONG FEATURES IN A QUIESCENT FILAMENT

International Nuclear Information System (INIS)

Joshi, Anand D.; Hanaoka, Yoichiro; Suematsu, Yoshinori; Morita, Satoshi; Yurchyshyn, Vasyl; Cho, Kyung-Suk

2016-01-01

We investigate the eruption of a quiescent filament located close to an active region. Large-scale activation was observed in only half of the filament in the form of pre-eruption oscillations. Consequently only this half erupted nearly 30 hr after the oscillations commenced. Time-slice diagrams of 171 Å images from the Atmospheric Imaging Assembly were used to study the oscillations. These were observed in several thin and long features connecting the filament spine to the chromosphere below. This study traces the origin of such features and proposes their possible interpretation. Small-scale magnetic flux cancellation accompanied by a brightening was observed at the footpoint of the features shortly before their appearance, in images recorded by the Helioseismic and Magnetic Imager. A slow rise of the filament was detected in addition to the oscillations, indicating a gradual loss of equilibrium. Our analysis indicates that a change in magnetic field connectivity between two neighbouring active regions and the quiescent filament resulted in a weakening of the overlying arcade of the filament, leading to its eruption. It is also suggested that the oscillating features are filament barbs, and the oscillations are a manifestation during the pre-eruption phase of the filaments.

PRE-ERUPTION OSCILLATIONS IN THIN AND LONG FEATURES IN A QUIESCENT FILAMENT

Energy Technology Data Exchange (ETDEWEB)

Joshi, Anand D.; Hanaoka, Yoichiro; Suematsu, Yoshinori; Morita, Satoshi [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Yurchyshyn, Vasyl; Cho, Kyung-Suk, E-mail: anand.joshi@nao.ac.jp [Korea Astronomy and Space Science Institute, Daejeon 34055 (Korea, Republic of)

2016-12-20

We investigate the eruption of a quiescent filament located close to an active region. Large-scale activation was observed in only half of the filament in the form of pre-eruption oscillations. Consequently only this half erupted nearly 30 hr after the oscillations commenced. Time-slice diagrams of 171 Å images from the Atmospheric Imaging Assembly were used to study the oscillations. These were observed in several thin and long features connecting the filament spine to the chromosphere below. This study traces the origin of such features and proposes their possible interpretation. Small-scale magnetic flux cancellation accompanied by a brightening was observed at the footpoint of the features shortly before their appearance, in images recorded by the Helioseismic and Magnetic Imager. A slow rise of the filament was detected in addition to the oscillations, indicating a gradual loss of equilibrium. Our analysis indicates that a change in magnetic field connectivity between two neighbouring active regions and the quiescent filament resulted in a weakening of the overlying arcade of the filament, leading to its eruption. It is also suggested that the oscillating features are filament barbs, and the oscillations are a manifestation during the pre-eruption phase of the filaments.

Josephson plasma resonance in vortex filament state of high temperature superconductors

International Nuclear Information System (INIS)

Matsuda, Yuji; Gaifullin, M.B.

1996-01-01

High temperature superconductors have the crystalline structure in which two-dimensional CuO 2 planes are piled in layers, consequently, the anisotropy of electroconductivity arises, and this brings about stable and low energy Josephson plasma in superconducting state. Also as to the vortex filament state of high temperature superconductors, the effect of thermal fluctuation due to low dimensionality, short coherence length and high transition temperature becomes conspicuous. In reality, these plasma and vortex filament state are related closely. Light reflection and plasma edge in superconducting state, Josephson plasma resonance in the vortex filament state of BiO 2 Sr 2 CaCu 2 O 8+δ , the plasma vibration in Josephson junction, Josephson plasma in magnetic field, Josephson plasma in the liquid state of vortex filament, Josephson plasma in the solid state of vortex filament, and Josephson plasma in parallel magnetic field are reported. The Josephson plasma resonance is the experimental means for exploring vortex filament state from microscopic standpoint, and its development hereafter is expected. (K.I.)

FSHD myoblasts fail to downregulate intermediate filament protein vimentin during myogenic differentiation.

Directory of Open Access Journals (Sweden)

Lipinski M.

2011-10-01

Full Text Available Facioscapulohumeral muscular dystrophy (FSHD is an autosomal dominant hereditary neuromuscular disorder. The clinical features of FSHD include weakness of the facial and shoulder girdle muscles followed by wasting of skeletal muscles of the pelvic girdle and lower extremities. Although FSHD myoblasts grown in vitro can be induced to differentiate into myotubes by serum starvation, the resulting FSHD myotubes have been shown previously to be morphologically abnormal. Aim. In order to find the cause of morphological anomalies of FSHD myotubes we compared in vitro myogenic differentiation of normal and FSHD myoblasts at the protein level. Methods. We induced myogenic differentiation of normal and FSHD myoblasts by serum starvation. We then compared protein extracts from proliferating myoblasts and differentiated myotubes using SDS-PAGE followed by mass spectrometry identification of differentially expressed proteins. Results. We demonstrated that the expression of vimentin was elevated at the protein and mRNA levels in FSHD myotubes as compared to normal myotubes. Conclusions. We demonstrate for the first time that in contrast to normal myoblasts, FSHD myoblasts fail to downregulate vimentin after induction of in vitro myogenic differentiation. We suggest that vimentin could be an easily detectable marker of FSHD myotubes

The versatility of hot-filament activated chemical vapor deposition

International Nuclear Information System (INIS)

Schaefer, Lothar; Hoefer, Markus; Kroeger, Roland

2006-01-01

In the field of activated chemical vapor deposition (CVD) of polycrystalline diamond films, hot-filament activation (HF-CVD) is widely used for applications where large deposition areas are needed or three-dimensional substrates have to be coated. We have developed processes for the deposition of conductive, boron-doped diamond films as well as for tribological crystalline diamond coatings on deposition areas up to 50 cm x 100 cm. Such multi-filament processes are used to produce diamond electrodes for advanced electrochemical processes or large batches of diamond-coated tools and parts, respectively. These processes demonstrate the high degree of uniformity and reproducibility of hot-filament CVD. The usability of hot-filament CVD for diamond deposition on three-dimensional substrates is well known for CVD diamond shaft tools. We also develop interior diamond coatings for drawing dies, nozzles, and thread guides. Hot-filament CVD also enables the deposition of diamond film modifications with tailored properties. In order to adjust the surface topography to specific applications, we apply processes for smooth, fine-grained or textured diamond films for cutting tools and tribological applications. Rough diamond is employed for grinding applications. Multilayers of fine-grained and coarse-grained diamond have been developed, showing increased shock resistance due to reduced crack propagation. Hot-filament CVD is also used for in situ deposition of carbide coatings and diamond-carbide composites, and the deposition of non-diamond, silicon-based films. These coatings are suitable as diffusion barriers and are also applied for adhesion and stress engineering and for semiconductor applications, respectively

3D Evolution of a Filament Disappearance Event Observed by STEREO

Science.gov (United States)

Gosain, S.; Schmieder, B.; Venkatakrishnan, P.; Chandra, R.; Artzner, G.

2009-10-01

A filament disappearance event was observed on 22 May 2008 during our recent campaign JOP 178. The filament, situated in the Southern Hemisphere, showed sinistral chirality consistent with the hemispheric rule. The event was well observed by several observatories, in particular by THEMIS. One day, before the disappearance, Hα observations showed up- and down-flows in adjacent locations along the filament, which suggest plasma motions along twisted flux rope. THEMIS and GONG observations show shearing photospheric motions leading to magnetic flux canceling around barbs. STEREO A, B spacecraft with separation angle 52.4°, showed quite different views of this untwisting flux rope in He ii 304 Å images. Here, we reconstruct the three-dimensional geometry of the filament during its eruption phase using STEREO EUV He ii 304 Å images and find that the filament was highly inclined to the solar normal. The He ii 304 Å movies show individual threads, which oscillate and rise to an altitude of about 120 Mm with apparent velocities of about 100 km s-1 during the rapid evolution phase. Finally, as the flux rope expands into the corona, the filament disappears by becoming optically thin to undetectable levels. No CME was detected by STEREO, only a faint CME was recorded by LASCO at the beginning of the disappearance phase at 02:00 UT, which could be due to partial filament eruption. Further, STEREO Fe xii 195 Å images showed bright loops beneath the filament prior to the disappearance phase, suggesting magnetic reconnection below the flux rope.

The MHD intermediate shock interaction with an intermediate wave: Are intermediate shocks physical?

International Nuclear Information System (INIS)

Wu, C.C.

1988-01-01

Contrary to the usual belief that MHD intermediate shocks are extraneous, the authors have recently shown by numerical solutions of dissipative MHD equations that intermediate shocks are admissible and can be formed through nonlinear steepening from a continuous wave. In this paper, he clarifies the differences between the conventional view and the results by studying the interaction of an MHD intermediate shock with an intermediate wave. The study reaffirms his results. In addition, the study shows that there exists a larger class of shocklike solutions in the time-dependent dissiaptive MHD equations than are given by the MHD Rankine-Hugoniot relations. it also suggests a mechanism for forming rotational discontinuities through the interaction of an intermediate shock with an intermediate wave. The results are of importance not only to the MHD shock theory but also to studies such as magnetic field reconnection models

Process for the production of superconductor containing filaments

Energy Technology Data Exchange (ETDEWEB)

Tuominen, Olli P. (Candler, NC); Hoyt, Matthew B. (Arden, NC); Mitchell, David F. (Asheville, NC); Morgan, Carol W. (Asheville, NC); Roberts, Clyde Gordon (Asheville, NC); Tyler, Robert A. (Canton, NC)

2002-01-01

Superconductor containing filaments having embedments of superconducting material surrounded by a rayon matrix are formed by preparing a liquid suspension which contains at least 10 weight percent superconducting material; forming a multicomponent filament having a core of the suspension and a viscose sheath which contains cellulose xanthate; and thereafter, regenerating cellulose from the cellulose xanthate to form a rayon matrix.

High-Resolution Observations of a Filament showing Activated Barb

Science.gov (United States)

Joshi, Anand; Martin, Sara F.; Mathew, Shibu; Srivastava, Nandita

2012-07-01

Analysis of a filament showing an activated barb using observations from the Dutch Open Telescope (DOT) on 2010 August 20 are presented. The DOT takes Doppler images in Hα, among other wavelengths, in a region about 110 × 110 arcsec^{2} in area, at a cadence of 30~seconds. The offline image restoration technique of speckle reconstruction is applied to obtain diffraction limited images. The filament developed a new barb in 10~minutes, which disappeared within the next 35~minutes. Such a rapid formation and disappearance of a filament barb is unusual, and has not been reported earlier. Line-of-sight velocity maps were constructed from the Doppler images of the target filament. We observe flows in the filament spine towards the barb location prior to its formation, and flows in the barb towards the spine during its disappearance. Photospheric magnetograms from Heliospheric Magnetic Imager on board the Solar Dynamics Observatory, at a cadence of 45~seconds, were used to determine the changes in magnetic flux in the region surrounding the barb location. The variation of magnetic flux in this duration supports the view that barbs are rooted in minor magnetic polarity. Our analysis shows that barbs can be short-lived and formation and disappearance of the barb was associated with cancellation of magnetic flux.

Controlling Plasma Channels through Ultrashort Laser Pulse Filamentation

Science.gov (United States)

Ionin, Andrey; Seleznev, Leonid; Sunchugasheva, Elena

2013-09-01

A review of studies fulfilled at the Lebedev Institute in collaboration with the Moscow State University and Institute of Atmospheric Optics in Tomsk on influence of various characteristics of ultrashort laser pulse on plasma channels formed under its filamentation is presented. Filamentation of high-power laser pulses with wavefront controlled by a deformable mirror, with cross-sections spatially formed by various diaphragms and with different wavelengths was experimentally and numerically studied. An application of plasma channels formed due to filamentation of ultrashort laser pulse including a train of such pulses for triggering and guiding long electric discharges is discussed. The research was supported by RFBR Grants 11-02-12061-ofi-m and 11-02-01100, and EOARD Grant 097007 through ISTC Project 4073 P

Automatic Segmentation and Quantification of Filamentous Structures in Electron Tomography.

Science.gov (United States)

Loss, Leandro A; Bebis, George; Chang, Hang; Auer, Manfred; Sarkar, Purbasha; Parvin, Bahram

2012-10-01

Electron tomography is a promising technology for imaging ultrastructures at nanoscale resolutions. However, image and quantitative analyses are often hindered by high levels of noise, staining heterogeneity, and material damage either as a result of the electron beam or sample preparation. We have developed and built a framework that allows for automatic segmentation and quantification of filamentous objects in 3D electron tomography. Our approach consists of three steps: (i) local enhancement of filaments by Hessian filtering; (ii) detection and completion (e.g., gap filling) of filamentous structures through tensor voting; and (iii) delineation of the filamentous networks. Our approach allows for quantification of filamentous networks in terms of their compositional and morphological features. We first validate our approach using a set of specifically designed synthetic data. We then apply our segmentation framework to tomograms of plant cell walls that have undergone different chemical treatments for polysaccharide extraction. The subsequent compositional and morphological analyses of the plant cell walls reveal their organizational characteristics and the effects of the different chemical protocols on specific polysaccharides.

Role of Glycolytic Intermediates in Global Regulation and Signal Transduction. Final Report

Energy Technology Data Exchange (ETDEWEB)

Liao, J.C.

2000-05-08

The goal of this project is to determine the role of glycolytic intermediates in regulation of cell physiology. It is known that many glycolytic intermediates are involved in regulation of enzyme activities at the kinetic level. However, little is known regarding the role of these metabolites in global regulation and signal transduction. This project aims to investigate the role of glycolytic intermediates in the regulation of gene expression.

Thick filament mechano-sensing is a calcium-independent regulatory mechanism in skeletal muscle.

Science.gov (United States)

Fusi, L; Brunello, E; Yan, Z; Irving, M

2016-10-31

Recent X-ray diffraction studies on actively contracting fibres from skeletal muscle showed that the number of myosin motors available to interact with actin-containing thin filaments is controlled by the stress in the myosin-containing thick filaments. Those results suggested that thick filament mechano-sensing might constitute a novel regulatory mechanism in striated muscles that acts independently of the well-known thin filament-mediated calcium signalling pathway. Here we test that hypothesis using probes attached to the myosin regulatory light chain in demembranated muscle fibres. We show that both the extent and kinetics of thick filament activation depend on thick filament stress but are independent of intracellular calcium concentration in the physiological range. These results establish direct control of myosin motors by thick filament mechano-sensing as a general regulatory mechanism in skeletal muscle that is independent of the canonical calcium signalling pathway.

Cytokeratin 8/18 expression indicates a poor prognosis in squamous cell carcinomas of the oral cavity

International Nuclear Information System (INIS)

Fillies, Thomas; Werkmeister, Richard; Packeisen, Jens; Brandt, Burkhard; Morin, Philippe; Weingart, Dieter; Joos, Ulrich; Buerger, Horst

2006-01-01

Intermediary filaments are involved in cell motility and cancer progression. In a variety of organs, the expression of distinct intermediary filaments are associated with patient prognosis. In this study, we seeked to define the prognostic potential of cytokeratin and vimentin expression patterns in squamous cell carcinomas (SCC's) of the oral cavity. 308 patients with histologically proven and surgically treated squamous cell carcinomas of the oral cavity were investigated for the immunohistochemical expression of a variety of intermediary filaments including high- and low-molecular weight cytokeratins (Ck's), such as Ck 5/6, Ck 8/18, Ck 1, CK 10, Ck 14, Ck 19 and vimentin, using the tissue microarray technique. Correlations between clinical features and the expression of Cytokeratins and vimentin were evaluated statistically by Kaplan-Meier curves and multivariate Cox regression analysis. The expression of Ck 8/18 and Ck 19 were overall significantly correlated with a poor clinical prognosis (Ck 8/18 p = 0.04; Ck19 p < 0.01). These findings could also be reproduced for Ck 8/18 in primary nodal-negative SCC's and held true in multivariate-analysis. No significant correlation with patient prognosis could be found for the expression of the other cytokeratins and for vimentin. The expression of Ck 8/18 in SCC's of the oral cavity is an independent prognostic marker and indicates a decreased overall and progression free survival. These results provide an extended knowledge about the role of intermediary filament expression patterns in SCC's

Avian influenza a virus budding morphology: spherical or filamentous?

Science.gov (United States)

Most strains of influenza A virus (IAV) can produce long (µm length) filamentous virus particles as well as ~100 nm diameter spherical virions. The function of the filamentous particles is unclear but is hypothesized to facilitate transmission within or from the respiratory tract. In mammalian IAVs,...

Swi5-Sfr1 protein stimulates Rad51-mediated DNA strand exchange reaction through organization of DNA bases in the presynaptic filament.

KAUST Repository

Fornander, Louise H

2013-12-03

The Swi5-Sfr1 heterodimer protein stimulates the Rad51-promoted DNA strand exchange reaction, a crucial step in homologous recombination. To clarify how this accessory protein acts on the strand exchange reaction, we have analyzed how the structure of the primary reaction intermediate, the Rad51/single-stranded DNA (ssDNA) complex filament formed in the presence of ATP, is affected by Swi5-Sfr1. Using flow linear dichroism spectroscopy, we observe that the nucleobases of the ssDNA are more perpendicularly aligned to the filament axis in the presence of Swi5-Sfr1, whereas the bases are more randomly oriented in the absence of Swi5-Sfr1. When using a modified version of the natural protein where the N-terminal part of Sfr1 is deleted, which has no affinity for DNA but maintained ability to stimulate the strand exchange reaction, we still observe the improved perpendicular DNA base orientation. This indicates that Swi5-Sfr1 exerts its activating effect through interaction with the Rad51 filament mainly and not with the DNA. We propose that the role of a coplanar alignment of nucleobases induced by Swi5-Sfr1 in the presynaptic Rad51/ssDNA complex is to facilitate the critical matching with an invading double-stranded DNA, hence stimulating the strand exchange reaction.

Sensitivity of RF-driven Plasma Filaments to Trace Gases

Science.gov (United States)

Burin, M. J.; Czarnocki, C. J.; Czarnocki, K.; Zweben, S. J.; Zwicker, A.

2011-10-01

Filamentary structures have been observed in many types of plasma discharges in both natural (e.g. lightning) and industrial systems (e.g. dielectric barrier discharges). Recent progress has been made in characterizing these structures, though various aspects of their essential physics remain unclear. A common example of this phenomenon can be found within a toy plasma globe (or plasma ball), wherein a primarily neon gas mixture near atmospheric pressure clearly and aesthetically displays filamentation. Recent work has provided the first characterization of these plasma globe filaments [Campanell et al., Physics of Plasmas 2010], where it was noticed that discharges of pure gases tend not to produce filaments. We have extended this initial work to investigate in greater detail the dependence of trace gases on filamentation within a primarily Neon discharge. Our preliminary results using a custom globe apparatus will be presented, along with some discussion of voltage dependencies. Newly supported by the NSF/DOE Partnership in Basic Plasma Science and Engineering.

Classical model of intermediate statistics

International Nuclear Information System (INIS)

Kaniadakis, G.

1994-01-01

In this work we present a classical kinetic model of intermediate statistics. In the case of Brownian particles we show that the Fermi-Dirac (FD) and Bose-Einstein (BE) distributions can be obtained, just as the Maxwell-Boltzmann (MD) distribution, as steady states of a classical kinetic equation that intrinsically takes into account an exclusion-inclusion principle. In our model the intermediate statistics are obtained as steady states of a system of coupled nonlinear kinetic equations, where the coupling constants are the transmutational potentials η κκ' . We show that, besides the FD-BE intermediate statistics extensively studied from the quantum point of view, we can also study the MB-FD and MB-BE ones. Moreover, our model allows us to treat the three-state mixing FD-MB-BE intermediate statistics. For boson and fermion mixing in a D-dimensional space, we obtain a family of FD-BE intermediate statistics by varying the transmutational potential η BF . This family contains, as a particular case when η BF =0, the quantum statistics recently proposed by L. Wu, Z. Wu, and J. Sun [Phys. Lett. A 170, 280 (1992)]. When we consider the two-dimensional FD-BE statistics, we derive an analytic expression of the fraction of fermions. When the temperature T→∞, the system is composed by an equal number of bosons and fermions, regardless of the value of η BF . On the contrary, when T=0, η BF becomes important and, according to its value, the system can be completely bosonic or fermionic, or composed both by bosons and fermions

The self-assembly, elasticity, and dynamics of cardiac thin filaments.

Science.gov (United States)

Tassieri, M; Evans, R M L; Barbu-Tudoran, L; Trinick, J; Waigh, T A

2008-03-15

Solutions of intact cardiac thin filaments were examined with transmission electron microscopy, dynamic light scattering (DLS), and particle-tracking microrheology. The filaments self-assembled in solution with a bell-shaped distribution of contour lengths that contained a population of filaments of much greater length than the in vivo sarcomere size ( approximately 1 mum) due to a one-dimensional annealing process. Dynamic semiflexible modes were found in DLS measurements at fast timescales (12.5 ns-0.0001 s). The bending modulus of the fibers is found to be in the range 4.5-16 x 10(-27) Jm and is weakly dependent on calcium concentration (with Ca2+ > or = without Ca2+). Good quantitative agreement was found for the values of the fiber diameter calculated from transmission electron microscopy and from the initial decay of DLS correlation functions: 9.9 nm and 9.7 nm with and without Ca2+, respectively. In contrast, at slower timescales and high polymer concentrations, microrheology indicates that the cardiac filaments act as short rods in solution according to the predictions of the Doi-Edwards chopsticks model (viscosity, eta approximately c(3), where c is the polymer concentration). This differs from the semiflexible behavior of long synthetic actin filaments at comparable polymer concentrations and timescales (elastic shear modulus, G' approximately c(1.4), tightly entangled) and is due to the relative ratio of the contour lengths ( approximately 30). The scaling dependence of the elastic shear modulus on the frequency (omega) for cardiac thin filaments is G' approximately omega(3/4 +/- 0.03), which is thought to arise from flexural modes of the filaments.

A CIRCULAR-RIBBON SOLAR FLARE FOLLOWING AN ASYMMETRIC FILAMENT ERUPTION

Energy Technology Data Exchange (ETDEWEB)

Liu, Chang; Deng, Na; Lee, Jeongwoo; Wang, Haimin [Space Weather Research Laboratory, New Jersey Institute of Technology, University Heights, Newark, NJ 07102-1982 (United States); Liu, Rui [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei 230026 (China); Pariat, Étienne [LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universits, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, F-92190 Meudon (France); Wiegelmann, Thomas [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig Weg 3, D-37077 Göttingen (Germany); Liu, Yang [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305-4085 (United States); Kleint, Lucia, E-mail: chang.liu@njit.edu [University of Applied Sciences and Arts Northwestern Switzerland, Bahnhofstrasse 6, 5210 Windisch (Switzerland)

2015-10-20

The dynamic properties of flare ribbons and the often associated filament eruptions can provide crucial information on the flaring coronal magnetic field. This Letter analyzes the GOES-class X1.0 flare on 2014 March 29 (SOL2014-03-29T17:48), in which we found an asymmetric eruption of a sigmoidal filament and an ensuing circular flare ribbon. Initially both EUV images and a preflare nonlinear force-free field model show that the filament is embedded in magnetic fields with a fan-spine-like structure. In the first phase, which is defined by a weak but still increasing X-ray emission, the western portion of the sigmoidal filament arches upward and then remains quasi-static for about five minutes. The western fan-like and the outer spine-like fields display an ascending motion, and several associated ribbons begin to brighten. Also found is a bright EUV flow that streams down along the eastern fan-like field. In the second phase that includes the main peak of hard X-ray (HXR) emission, the filament erupts, leaving behind two major HXR sources formed around its central dip portion and a circular ribbon brightened sequentially. The expanding western fan-like field interacts intensively with the outer spine-like field, as clearly seen in running difference EUV images. We discuss these observations in favor of a scenario where the asymmetric eruption of the sigmoidal filament is initiated due to an MHD instability and further facilitated by reconnection at a quasi-null in corona; the latter is in turn enhanced by the filament eruption and subsequently produces the circular flare ribbon.

Blowout Surge due to Interaction between a Solar Filament and Coronal Loops

Energy Technology Data Exchange (ETDEWEB)

Li, Haidong; Jiang, Yunchun; Yang, Jiayan; Yang, Bo; Xu, Zhe; Bi, Yi; Hong, Junchao; Chen, Hechao [Yunnan Observatories, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming, 650216 (China); Qu, Zhining, E-mail: lhd@ynao.ac.cn [Department of Physics, School of Science, Sichuan University of Science and Engineering, Zigong 643000 (China)

2017-06-20

We present an observation of the interaction between a filament and the outer spine-like loops that produces a blowout surge within one footpoint of large-scale coronal loops on 2015 February 6. Based the observation of the AIA 304 and 94 Å, the activated filament is initially embedded below a dome of a fan-spine configuration. Due to the ascending motion, the erupting filament reconnects with the outer spine-like field. We note that the material in the filament blows out along the outer spine-like field to form the surge with a wider spire, and a two-ribbon flare appears at the site of the filament eruption. In this process, small bright blobs appear at the interaction region and stream up along the outer spine-like field and down along the eastern fan-like field. As a result, a leg of the filament becomes radial and the material in it erupts, while another leg forms the new closed loops. Our results confirm that the successive reconnection occurring between the erupting filament and the coronal loops may lead to a strong thermal/magnetic pressure imbalance, resulting in a blowout surge.

EVIDENCE OF FILAMENT UPFLOWS ORIGINATING FROM INTENSITY OSCILLATIONS ON THE SOLAR SURFACE

International Nuclear Information System (INIS)

Cao, Wenda; Goode, Philip R.; Ning, Zongjun; Yurchyshyn, Vasyl; Ji Haisheng

2010-01-01

A filament footpoint rooted in an active region (NOAA 11032) was well observed for about 78 minutes with the 1.6 m New Solar Telescope at the Big Bear Solar Observatory on 2009 November 18 in Hα ±0.75 A. This data set had high cadence (∼15 s) and high spatial resolution (∼0.''1) and offered a unique opportunity to study filament dynamics. As in previous findings from space observations, several dark intermittent upflows were identified, and they behave in groups at isolated locations along the filament. However, we have two new findings. First, we find that the dark upflows propagating along the filament channel are strongly associated with the intensity oscillations on the solar surface around the filament footpoints. The upflows start at the same time as the peak in the oscillations, illustrating that the upflow velocities are well correlated with the oscillations. Second, the intensity of one of the seven upflows detected in our data set exhibits a clear periodicity when the upflow propagates along the filament. The periods gradually vary from ∼10 to ∼5 minutes. Our results give observational clues on the driving mechanism of the upflows in the filament.

Prognostic value and clinicopathological significance of serum- and tissue-based cytokeratin 18 express level in breast cancer: a meta-analysis.

Science.gov (United States)

Yang, Jiangling; Gao, Sicheng; Xu, Jian; Zhu, Junfeng

2018-04-27

Cytokeratin 18 (CK18), a type I cytokeratin of the intermediate filament family, has been associated with the prognosis of cancer patients for decades. However, its exact role in predicting the clinical outcome of breast cancer remains controversial. To comprehensively investigated the prognostic value of CK18 in breast cancer, a systematically meta-analysis was conducted to explore the association between CK18 expression and overall survival. Literature collection was conducted by retrieving electronic databases Pubmed, Cochrane Library, Web of Science, EMBASE, and OVID completely (up to January 1, 2017). Nine relevant studies with 4857 cases assessing the relationship between CK18 high expression and the outcome of breast cancer patients were enrolled in our analysis. The results indicated that the high level of CK18 expression was significantly associated with overall survival of breast cancer patients via a specimen-depended manner. Reports which used serum to detect the expression of CK18 predicted a poor outcome of breast cancer (HR = 1.24, 95%CI: 1.11-1.38, P present study demonstrated that CK18 might be served as a novel biomarker to predict clinicopathological features and the outcome of breast cancer. © 2018 The Author(s).

Developments in hot-filament metal oxide deposition (HFMOD)

Energy Technology Data Exchange (ETDEWEB)

Durrant, Steven F. [Laboratorio de Plasmas Tecnologicos, Campus Experimental de Sorocaba, Universidade Estadual Paulista (UNESP), Avenida Tres de Marco, 511, Alto de Boa Vista, 18087-180 Sorocaba, SP (Brazil)], E-mail: steve@sorocaba.unesp.br; Trasferetti, Benedito C. [Departamento de Policia Federal, Superintendencia Regional no Piaui, Setor Tecnico-Cientifico, Avenida Maranhao, 1022/N, 64.000-010, Teresina, PI (Brazil); Scarminio, Jair [Departamento de Fisica, Universidade Estadual de Londrina (UEL), 86051-990, Londrina, PR (Brazil); Davanzo, Celso U. [Instituto de Quimica, Universidade Estadual de Campinas (UNICAMP), 13083-970, Campinas, SP (Brazil); Rouxinol, Francisco P.M.; Gelamo, Rogerio V.; Bica de Moraes, Mario A. [Laboratorio de Processos de Plasma, Departamento de Fisica Aplicada, Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas (UNICAMP), 13083-970, Campinas, SP (Brazil)

2008-01-15

Hot-filament metal oxide deposition (HFMOD) is a variant of conventional hot-filament chemical vapor deposition (HFCVD) recently developed in our laboratory and successfully used to obtain high-quality, uniform films of MO{sub x}, WO{sub x} and VO{sub x}. The method employs the controlled oxidation of a filament of a transition metal heated to 1000 deg. C or more in a rarefied oxygen atmosphere (typically, of about 1 Pa). Metal oxide vapor formed on the surface of the filament is transported a few centimetres to deposit on a suitable substrate. Key system parameters include the choice of filament material and diameter, the applied current and the partial pressures of oxygen in the chamber. Relatively high film deposition rates, such as 31 nm min{sup -1} for MoO{sub x}, are obtained. The film stoichiometry depends on the exact deposition conditions. MoO{sub x} films, for example, present a mixture of MoO{sub 2} and MoO{sub 3} phases, as revealed by XPS. As determined by Li{sup +} intercalation using an electrochemical cell, these films also show a colouration efficiency of 19.5 cm{sup 2} C{sup -1} at a wavelength of 700 nm. MO{sub x} and WO{sub x} films are promising in applications involving electrochromism and characteristics of their colouring/bleaching cycles are presented. The chemical composition and structure of VO{sub x} films examined using IRRAS (infrared reflection-absorption spectroscopy), RBS (Rutherford backscattering spectrometry) and XPS (X-ray photoelectron spectrometry) are also presented.

A first approach to filament dynamics

International Nuclear Information System (INIS)

Silva, P E S; De Abreu, F Vistulo; Dias, R G; Simoes, R

2010-01-01

Modelling elastic filament dynamics is a topic of high interest due to the wide range of applications. However, it has reached a high level of complexity in the literature, making it unaccessible to a beginner. In this paper we explain the main steps involved in the computational modelling of the dynamics of an elastic filament. We first derive equations governing the dynamics of an elastic lament suitable for a computer simulation implementation. The derivation starts from the relation between forces and potential energy in conservative systems in order to derive the equation of motion of any bead in the filament. Only two-dimensional movements are considered, but extensions to three dimensions can follow similar lines. Suggestions for computer implementations are provided in Matlab as well as an example of application related to the generation of musical sounds. This example allows a critical analysis of the numerical results obtained using a cross-disciplinary perspective. Since derivations start from basic physics equations, use simple calculus and computational implementations are straightforward, this paper proposes a different approach to introduce simple molecular dynamics simulations or animations of real systems in undergraduate elasticity or computer modelling courses.

Analysis of the axial filaments of Treponema hyodysenteriae by SDS-PAGE and immunoblotting.

Science.gov (United States)

Kent, K A; Sellwood, R; Lemcke, R M; Burrows, M R; Lysons, R J

1989-06-01

Purified axial filaments from eight serotypes of Treponema hyodysenteriae and two non-pathogenic intestinal spirochaetes were characterized by SDS-PAGE and Western blotting. Axial filaments of all ten strains had similar SDS-PAGE profiles; five major axial filament polypeptides were identified, with molecular masses of 43.8, 38, 34.8, 32.8 and 29.4 kDa. Hyperimmune gnotobiotic pig serum raised against purified axial filaments of strain P18A (serotype 4) cross-reacted with all other serotypes and with the non-pathogens, and convalescent serum taken from a pig with persistent swine dysentery also showed a strong response to the axial filament polypeptides. Hyperimmune gnotobiotic pig serum raised against axial filaments failed to agglutinate viable organisms and did not inhibit growth in vitro. Hence, the axial filaments of T. hyodysenteriae have been identified as major immunodominant antigens, although the role that antibodies to these antigens play in protection has yet to be established.

Filament instability under constant loads

Science.gov (United States)

Monastra, A. G.; Carusela, M. F.; D’Angelo, M. V.; Bruno, L.

2018-04-01

Buckling of semi-flexible filaments appears in different systems and scales. Some examples are: fibers in geophysical applications, microtubules in the cytoplasm of eukaryotic cells and deformation of polymers freely suspended in a flow. In these examples, instabilities arise when a system’s parameter exceeds a critical value, being the Euler force the most known. However, the complete time evolution and wavelength of buckling processes are not fully understood. In this work we solve analytically the time evolution of a filament under a constant compressive force in the small amplitude approximation. This gives an insight into the variable force scenario in terms of normal modes. The evolution is highly sensitive to the initial configuration and to the magnitude of the compressive load. This model can be a suitable approach to many different real situations.

Structures of actin-like ParM filaments show architecture of plasmid-segregating spindles.

Science.gov (United States)

Bharat, Tanmay A M; Murshudov, Garib N; Sachse, Carsten; Löwe, Jan

2015-07-02

Active segregation of Escherichia coli low-copy-number plasmid R1 involves formation of a bipolar spindle made of left-handed double-helical actin-like ParM filaments. ParR links the filaments with centromeric parC plasmid DNA, while facilitating the addition of subunits to ParM filaments. Growing ParMRC spindles push sister plasmids to the cell poles. Here, using modern electron cryomicroscopy methods, we investigate the structures and arrangements of ParM filaments in vitro and in cells, revealing at near-atomic resolution how subunits and filaments come together to produce the simplest known mitotic machinery. To understand the mechanism of dynamic instability, we determine structures of ParM filaments in different nucleotide states. The structure of filaments bound to the ATP analogue AMPPNP is determined at 4.3 Å resolution and refined. The ParM filament structure shows strong longitudinal interfaces and weaker lateral interactions. Also using electron cryomicroscopy, we reconstruct ParM doublets forming antiparallel spindles. Finally, with whole-cell electron cryotomography, we show that doublets are abundant in bacterial cells containing low-copy-number plasmids with the ParMRC locus, leading to an asynchronous model of R1 plasmid segregation.

Ectopic Cdx2 expression in murine esophagus models an intermediate stage in the emergence of Barrett's esophagus.

Directory of Open Access Journals (Sweden)

Jianping Kong

2011-04-01

Full Text Available Barrett's esophagus (BE is an intestinal metaplasia that occurs in the setting of chronic acid and bile reflux and is associated with a risk for adenocarcinoma. Expression of intestine-specific transcription factors in the esophagus likely contributes to metaplasia development. Our objective was to explore the effects of an intestine-specific transcription factor when expressed in the mouse esophageal epithelium. Transgenic mice were derived in which the transcription factor Cdx2 is expressed in squamous epithelium using the murine Keratin-14 gene promoter. Effects of the transgene upon cell proliferation and differentiation, gene expression, and barrier integrity were explored. K14-Cdx2 mice express the Cdx2 transgene in esophageal squamous tissues. Cdx2 expression was associated with reduced basal epithelial cell proliferation and altered cell morphology. Ultrastructurally two changes were noted. Cdx2 expression was associated with dilated space between the basal cells and diminished cell-cell adhesion caused by reduced Desmocollin-3 mRNA and protein expression. This compromised epithelial barrier function, as the measured trans-epithelial electrical resistance (TEER of the K14-Cdx2 epithelium was significantly reduced compared to controls (1189 Ohm*cm(2 ±343.5 to 508 Ohm*cm(2±92.48, p = 0.0532. Secondly, basal cells with features of a transitional cell type, intermediate between keratinocytes and columnar Barrett's epithelial cells, were observed. These cells had reduced keratin bundles and increased endoplasmic reticulum levels, suggesting the adoption of secretory-cell features. Moreover, at the ultrastructural level they resembled "Distinctive" cells associated with multilayered epithelium. Treatment of the K14-Cdx2 mice with 5'-Azacytidine elicited expression of BE-associated genes including Cdx1, Krt18, and Slc26a3/Dra, suggesting the phenotype could be advanced under certain conditions. We conclude that ectopic Cdx2 expression in

Clinical strains of Lactobacillus reduce the filamentation of Candida albicans and protect Galleria mellonella against experimental candidiasis.

Science.gov (United States)

Rossoni, Rodnei Dennis; Dos Santos Velloso, Marisol; Figueiredo, Lívia Mara Alves; Martins, Carolina Pistille; Jorge, Antonio Olavo Cardoso; Junqueira, Juliana Campos

2018-05-01

Candida albicans is the most common human fungal pathogen and can grow as yeast or filaments, depending on the environmental conditions. The filamentous form is of particular interest because it can play a direct role in adherence and pathogenicity. Therefore, the purpose of this study was to evaluate the effects of three clinical strains of Lactobacillus on C. albicans filamentation as well as their probiotic potential in pathogen-host interactions via an experimental candidiasis model study in Galleria mellonella. We used the reference strain Candida albicans ATCC 18804 and three clinical strains of Lactobacillus: L. rhamnosus strain 5.2, L. paracasei strain 20.3, and L. fermentum strain 20.4. First, the capacity of C. albicans to form hyphae was tested in vitro through association with the Lactobacillus strains. After that, we verified the ability of these strains to attenuate experimental candidiasis in a Galleria mellonella model through a survival curve assay. Regarding the filamentation assay, a significant reduction in hyphae formation of up to 57% was observed when C. albicans was incubated in the presence of the Lactobacillus strains, compared to a control group composed of only C. albicans. In addition, when the larvae were pretreated with Lactobacillus spp. prior to C. albicans infection, the survival rate of G. mellonela increased in all experimental groups. We concluded that Lactobacillus influences the growth and expression C. albicans virulence factors, which may interfere with the pathogenicity of these microorganisms.

Differentiation of Serratia liquefaciens into swarm cells is controlled by the expression of the flhD master operon

DEFF Research Database (Denmark)

Eberl, L; Christiansen, Gunna; Molin, S

1996-01-01

The velocity with which a swarming colony of Serratia liquefaciens colonizes the surface of a suitable solid substratum was controlled by modulating the expression of the flhD master operon. In liquid medium, the stimulation of flhD expression resulted in filamentous, multinucleate, and hyperflag......The velocity with which a swarming colony of Serratia liquefaciens colonizes the surface of a suitable solid substratum was controlled by modulating the expression of the flhD master operon. In liquid medium, the stimulation of flhD expression resulted in filamentous, multinucleate...

A Bipolar Spindle of Antiparallel ParM Filaments Drives Bacterial Plasmid Segregation

DEFF Research Database (Denmark)

Gayathri, P; Fujii, T; Møller-Jensen, Jakob

2012-01-01

the spindle between ParRC complexes on sister plasmids. Using a combination of structural work and total internal reflection fluorescence microscopy, we show that ParRC bound and could accelerate growth at only one end of polar ParM filaments, mechanistically resembling eukaryotic formins. The architecture...... of ParM filaments enabled two ParRC-bound filaments to associate in an antiparallel orientation, forming a bipolar spindle. The spindle elongated as a bundle of at least two antiparallel filaments, thereby pushing two plasmid clusters toward the poles....

Covisualization in living onion cells of putative integrin, putative spectrin, actin, putative intermediate filaments, and other proteins at the cell membrane and in an endomembrane sheath

Science.gov (United States)

Reuzeau, C.; Doolittle, K. W.; McNally, J. G.; Pickard, B. G.; Evans, M. L. (Principal Investigator)

1997-01-01

Covisualizations with wide-field computational optical-sectioning microscopy of living epidermal cells of the onion bulb scale have evidenced two major new cellular features. First, a sheath of cytoskeletal elements clads the endomembrane system. Similar elements clad the inner faces of punctate plasmalemmal sites interpreted as plasmalemmal control centers. One component of the endomembrane sheath and plasmalemmal control center cladding is anti-genicity-recognized by two injected antibodies against animal spectrin. Immunoblots of separated epidermal protein also showed bands recognized by these antibodies. Injected phalloidin identified F-actin with the same cellular distribution pattern, as did antibodies against intermediate-filament protein and other cytoskeletal elements known from animal cells. Injection of general protein stains demonstrated the abundance of endomembrane sheath protein. Second, the endomembrane system, like the plasmalemmal puncta, contains antigen recognized by an anti-beta 1 integrin injected into the cytoplasm. Previously, immunoblots of separated epidermal protein were shown to have a major band recognized both by this antibody prepared against a peptide representing the cytosolic region of beta 1 integrin and an antibody against the matrix region of beta 1 integrin. The latter antiboby also identified puncta at the external face of protoplasts. It is proposed that integrin and associated transmembrane proteins secure the endomembrane sheath and transmit signals between it and the lumen or matrix of the endoplasmic reticulum and organellar matrices. This function is comparable to that proposed for such transmembrane linkers in the plasmalemmal control centers, which also appear to bind cytoskeleton and a host of related molecules and transmit signals between them and the wall matrix. It is at the plasmalemmal control centers that the endoplasmic reticulum, a major component of the endomembrane system, attaches to the plasma membrane.

Structure determination of helical filaments by solid-state NMR spectroscopy

Science.gov (United States)

Ahmed, Mumdooh; Spehr, Johannes; König, Renate; Lünsdorf, Heinrich; Rand, Ulfert; Lührs, Thorsten; Ritter, Christiane

2016-01-01

The controlled formation of filamentous protein complexes plays a crucial role in many biological systems and represents an emerging paradigm in signal transduction. The mitochondrial antiviral signaling protein (MAVS) is a central signal transduction hub in innate immunity that is activated by a receptor-induced conversion into helical superstructures (filaments) assembled from its globular caspase activation and recruitment domain. Solid-state NMR (ssNMR) spectroscopy has become one of the most powerful techniques for atomic resolution structures of protein fibrils. However, for helical filaments, the determination of the correct symmetry parameters has remained a significant hurdle for any structural technique and could thus far not be precisely derived from ssNMR data. Here, we solved the atomic resolution structure of helical MAVSCARD filaments exclusively from ssNMR data. We present a generally applicable approach that systematically explores the helical symmetry space by efficient modeling of the helical structure restrained by interprotomer ssNMR distance restraints. Together with classical automated NMR structure calculation, this allowed us to faithfully determine the symmetry that defines the entire assembly. To validate our structure, we probed the protomer arrangement by solvent paramagnetic resonance enhancement, analysis of chemical shift differences relative to the solution NMR structure of the monomer, and mutagenesis. We provide detailed information on the atomic contacts that determine filament stability and describe mechanistic details on the formation of signaling-competent MAVS filaments from inactive monomers. PMID:26733681

Filament Channel Formation, Eruption, and Jet Generation

Science.gov (United States)

DeVore, C. Richard; Antiochos, Spiro K.; Karpen, Judith T.

2017-08-01

The mechanism behind filament-channel formation is a longstanding mystery, while that underlying the initiation of coronal mass ejections and jets has been studied intensively but is not yet firmly established. In previous work, we and collaborators have investigated separately the consequences of magnetic-helicity condensation (Antiochos 2013) for forming filament channels (Zhao et al. 2015; Knizhnik et al. 2015, 2017a,b) and of the embedded-bipole model (Antiochos 1996) for generating reconnection-driven jets (Pariat et al. 2009, 2010, 2015, 2016; Wyper et al. 2016, 2017). Now we have taken a first step toward synthesizing these two lines of investigation. Our recent study (Karpen et al. 2017) of coronal-hole jets with gravity and wind employed an ad hoc, large-scale shear flow at the surface to introduce magnetic free energy and form the filament channel. In this effort, we replace the shear flow with an ensemble of local rotation cells, to emulate the Sun’s ever-changing granules and supergranules. As in our previous studies, we find that reconnection between twisted flux tubes within the closed-field region concentrates magnetic shear and free energy near the polarity inversion line, forming the filament channel. Onset of reconnection between this field and the external, unsheared, open field releases stored energy to drive the impulsive jet. We discuss the results of our new simulations with implications for understanding solar activity and space weather.

Magnetic structure of an activated filament in a flaring active region

Science.gov (United States)

Sasso, C.; Lagg, A.; Solanki, S. K.

2014-01-01

Aims: While the magnetic field in quiescent prominences has been widely investigated, less is known about the field in activated prominences. We report observational results on the magnetic field structure of an activated filament in a flaring active region. In particular, we studied its magnetic structure and line-of-sight flows during its early activated phase, shortly before it displayed signs of rotation. Methods: We inverted the Stokes profiles of the chromospheric He i 10 830 Å triplet and the photospheric Si i 10 827 Å line observed in this filament by the Vacuum Tower Telescope on Tenerife. Using these inversion results, we present and interpret the first maps of the velocity and magnetic field obtained in an activated filament, both in the photosphere and the chromosphere. Results: Up to five different magnetic components are found in the chromospheric layers of the filament, while outside the filament a single component is sufficient to reproduce the observations. Magnetic components displaying an upflow are preferentially located towards the centre of the filament, while the downflows are concentrated along its periphery. Moreover, the upflowing gas is associated with an opposite-polarity magnetic configuration with respect to the photosphere, while the downflowing gas is associated with a same-polarity configuration. Conclusions: The activated filament has a very complex structure. Nonetheless, it is compatible with a flux rope, albeit a distorted one, in the normal configuration. The observations are best explained by a rising flux rope in which part of the filament material is still stably stored (upflowing material, rising with the field), while the rest is no longer stably stored and flows down along the field lines. The movie is available in electronic form at http://www.aanda.org

Mucosal and systemic immune responses elicited by recombinant Lactococcus lactis expressing a fusion protein composed of pertussis toxin and filamentous hemagglutinin from Bordetella pertussis.

Science.gov (United States)

Torkashvand, Ali; Bahrami, Fariborz; Adib, Minoo; Ajdary, Soheila

2018-05-05

We constructed a food-grade expression system harboring a F1S1 fusion protein of Bordetella pertussis to be produced in Lactococcus lactis NZ3900 as a new oral vaccine model against whooping cough, caused by B. pertussis. F1S1 was composed of N-terminally truncated S1 subunit of pertussis toxin and type I immunodominant domain of filamentous hemagglutinin which are both known as protective immunogens against pertussis. The recombinant L. lactis was administered via oral or intranasal routes to BALB/c mice and the related specific systemic and mucosal immune responses were then evaluated. The results indicated significantly higher levels of specific IgA in the lung extracts and IgG in sera of mucosally-immunized mice, compared to their controls. It was revealed that higher levels of IgG2a, compared to IgG1, were produced in all mucosally-immunized mice. Moreover, immunized mice developed Th1 responses with high levels of IFN-γ production by the spleen cells. These findings provide evidence for L. lactis to be used as a suitable vehicle for expression and delivery of F1S1 fusion protein to mucosa and induction of appropriate systemic and mucosal immune responses against pertussis. Copyright © 2018 Elsevier Ltd. All rights reserved.

Influence of plasma background including neutrals on scrape-off layer filaments using 3D simulations

Directory of Open Access Journals (Sweden)

D. Schwörer

2017-08-01

Full Text Available This paper investigates the effect of the plasma background, including neutrals in a self-consistent way, on filaments in the scrape-off layer (SOL of fusion devices. A strong dependency of filament motion on background density and temperature is observed. The radial filament motion shows an increase in velocity with decreasing background density and increasing background temperature. In the simulations presented here, three neutral-filament interaction models have been compared, one with a static neutral background, one with no interaction between filaments and neutrals, and one co-evolving the neutrals self consistently with the filaments. With the background conditions employed here, which do not show detachment, there are no significant effects of neutrals on filaments, as by the time the filament reaches maximum velocity, the neutral density has not changed significantly.

Collective dynamics of populations of weakly correlated filaments of incoherent white light

International Nuclear Information System (INIS)

Guo, Jinxin; Sheridan, John T; Saravanamuttu, Kalaichelvi

2013-01-01

We examined the dynamics of two populations of self-trapped filaments of spatially and temporally incoherent white light. The populations consisted of (i) independent filaments generated through self-trapping of incandescent speckles, and (ii) co-dependent filaments created through modulation instability of a broad incandescent beam. Both filament populations were positionally stable in conditions where individual pairs of self-trapped beams interact strongly. Both also acquired significantly broad intensity distributions, which were independent of their parent optical fields; a small but persistent number of high-intensity filaments was identified in both cases. These studies provide accessible routes to weakly correlated ensembles, insight into their collective behaviour such as self-stabilization and self-selected intensity distributions, and reveal intriguing similarities between the dynamics of two populations of different origins. (paper)

Chandra and XMM-Newton Observations of the Abell 3395/Abell 3391 Intercluster Filament

Science.gov (United States)

Alvarez, Gabriella E.; Randall, Scott W.; Bourdin, Hervé; Jones, Christine; Holley-Bockelmann, Kelly

2018-05-01

We present Chandra and XMM-Newton X-ray observations of the Abell 3391/Abell 3395 intercluster filament. It has been suggested that the galaxy clusters Abell 3395, Abell 3391, and the galaxy group ESO-161 -IG 006 located between the two clusters, are in alignment along a large-scale intercluster filament. We find that the filament is aligned close to the plane of the sky, in contrast to previous results. We find a global projected filament temperature kT = {4.45}-0.55+0.89 keV, electron density {n}e={1.08}-0.05+0.06× {10}-4 cm‑3, and {M}gas}={2.7}-0.1+0.2 × {10}13 M ⊙. The thermodynamic properties of the filament are consistent with that of the intracluster medium (ICM) of Abell 3395 and Abell 3391, suggesting that the filament emission is dominated by ICM gas that has been tidally disrupted during an early stage merger between these two clusters. We present temperature, density, entropy, and abundance profiles across the filament. We find that the galaxy group ESO-161 may be undergoing ram-pressure-stripping in the low-density environment at or near the virial radius of both clusters, due to its rapid motion through the filament.

Flapping modes of three filaments placed side by side in a free stream

Science.gov (United States)

Tian, Fang-Bao; Luo, Haoxiang; Zhu, Luoding; Lu, Xi-Yun

2010-11-01

Flexible filaments flapping in a surrounding flow are useful models for understanding the flow-induced vibration and mimicking the schooling behavior of fish. In the present work, the coupled modes of three identical filaments in a side-by- side arrangement are studied using the linear stability analysis and also an immersed boundary--lattice Boltzmann method for low Reynolds numbers (Re on order of 100). The numerical simulations show that the system dynamics exhibits several patterns that depend on the spacing between the filaments. Among these patterns, three can be predicted by the linear analysis and have been reported before. These modes are: (1) the three filaments all flap in phase; (2) the two outer filaments are out of phase while the middle one is stable; (3) the two outer filaments are in phase while the middle one is out of phase. The simulations also identified two additional modes: (1) the outer two filaments are out of phase while the middle one flaps at a frequency reduced by half; (2) the outer two filaments are out of phase while the middle one flaps at a slightly different frequency. In addition to the vibratory modes, the drag force and the flapping amplitude are also computed, and the implication of the result will be discussed.

Numerical study of inertial effects on the rheology of filament suspensions

Science.gov (United States)

Alizad Banaei, Arash; Rosti, Marco Edoardo; Brandt, Luca

2017-11-01

Significant work has been devoted to modeling fiber suspensions as they occur in many applications such as paper and food industries. Most of the works are limited to the motion of rigid cylindrical rods in low Stokes flows. Here, we investigate the rheological properties of flexible filament suspensions by means of numerical simulations. We considered the filaments as one-dimensional inextensible slender bodies obeying the Euler-Bernoulli equations and study the effect of flexibility, flow inertia and volume fraction on the rheology of the suspensions. The numerical simulations are performed using the Immersed Boundary Method to model the fluid/structure interaction. The results indicate that the inertia has significant effect on the relative viscosity of the suspensions. The effect is larger for less deformable filaments. The filament suspensions exhibit viscoelastic behavior and the first normal stress has a maximum for moderate flexibilities. The relative viscosity increases with volume fraction of the filaments and it is more sensitive to the volume fraction for larger Reynolds numbers. For a constant flexibility, the mean end-to-end distance of the filaments decreases with Reynolds number and the mean velocity fluctuations of the fluid increases with the Reynolds number. European Research Council, Grant No. ERC-2013-CoG- 616186, TRITOS; SNIC (the Swedish National Infrastructure for Computing).

Accurate simulation dynamics of microscopic filaments using "caterpillar" Oseen hydrodynamics

NARCIS (Netherlands)

Bailey, A.G.; Lowe, C.P.; Pagonabarraga, I.; Cosentino Lagomarsino, M.

2009-01-01

Microscopic semiflexible filaments suspended in a viscous fluid are widely encountered in biophysical problems. The classic example is the flagella used by microorganisms to generate propulsion. Simulating the dynamics of these filaments numerically is complicated because of the coupling between the

3D Filament Network Segmentation with Multiple Active Contours

Science.gov (United States)

Xu, Ting; Vavylonis, Dimitrios; Huang, Xiaolei

2014-03-01

Fluorescence microscopy is frequently used to study two and three dimensional network structures formed by cytoskeletal polymer fibers such as actin filaments and microtubules. While these cytoskeletal structures are often dilute enough to allow imaging of individual filaments or bundles of them, quantitative analysis of these images is challenging. To facilitate quantitative, reproducible and objective analysis of the image data, we developed a semi-automated method to extract actin networks and retrieve their topology in 3D. Our method uses multiple Stretching Open Active Contours (SOACs) that are automatically initialized at image intensity ridges and then evolve along the centerlines of filaments in the network. SOACs can merge, stop at junctions, and reconfigure with others to allow smooth crossing at junctions of filaments. The proposed approach is generally applicable to images of curvilinear networks with low SNR. We demonstrate its potential by extracting the centerlines of synthetic meshwork images, actin networks in 2D TIRF Microscopy images, and 3D actin cable meshworks of live fission yeast cells imaged by spinning disk confocal microscopy.

Decidable and undecidable arithmetic functions in actin filament networks

Science.gov (United States)

Schumann, Andrew

2018-01-01

The plasmodium of Physarum polycephalum is very sensitive to its environment, and reacts to stimuli with appropriate motions. Both the sensory and motor stages of these reactions are explained by hydrodynamic processes, based on fluid dynamics, with the participation of actin filament networks. This paper is devoted to actin filament networks as a computational medium. The point is that actin filaments, with contributions from many other proteins like myosin, are sensitive to extracellular stimuli (attractants as well as repellents), and appear and disappear at different places in the cell to change aspects of the cell structure—e.g. its shape. By assembling and disassembling actin filaments, some unicellular organisms, like Amoeba proteus, can move in response to various stimuli. As a result, these organisms can be considered a simple reversible logic gate—extracellular signals being its inputs and motions its outputs. In this way, we can implement various logic gates on amoeboid behaviours. These networks can embody arithmetic functions within p-adic valued logic. Furthermore, within these networks we can define the so-called diagonalization for deducing undecidable arithmetic functions.

Internal epithelia in Drosophila display rudimentary competence to form cytoplasmic networks of transgenic human vimentin.

Science.gov (United States)

Gullmets, Josef; Torvaldson, Elin; Lindqvist, Julia; Imanishi, Susumu Y; Taimen, Pekka; Meinander, Annika; Eriksson, John E

2017-12-01

Cytoplasmic intermediate filaments (cIFs) are found in all eumetazoans, except arthropods. To investigate the compatibility of cIFs in arthropods, we expressed human vimentin (hVim), a cIF with filament-forming capacity in vertebrate cells and tissues, transgenically in Drosophila Transgenic hVim could be recovered from whole-fly lysates by using a standard procedure for intermediate filament (IF) extraction. When this procedure was used to test for the possible presence of IF-like proteins in flies, only lamins and tropomyosin were observed in IF-enriched extracts, thereby providing biochemical reinforcement to the paradigm that arthropods lack cIFs. In Drosophila , transgenic hVim was unable to form filament networks in S2 cells and mesenchymal tissues; however, cage-like vimentin structures could be observed around the nuclei in internal epithelia, which suggests that Drosophila retains selective competence for filament formation. Taken together, our results imply that although the filament network formation competence is partially lost in Drosophila , a rudimentary filament network formation ability remains in epithelial cells. As a result of the observed selective competence for cIF assembly in Drosophila , we hypothesize that internal epithelial cIFs were the last cIFs to disappear from arthropods.-Gullmets, J., Torvaldson, E., Lindqvist, J., Imanishi, S. Y., Taimen, P., Meinander, A., Eriksson, J. E. Internal epithelia in Drosophila display rudimentary competence to form cytoplasmic networks of transgenic human vimentin. © FASEB.

Filament structures at the plasma edge on MAST

International Nuclear Information System (INIS)

Kirk, A; Ayed, N Ben; Counsell, G; Dudson, B; Eich, T; Herrmann, A; Koch, B; Martin, R; Meakins, A; Saarelma, S; Scannell, R; Tallents, S; Walsh, M; Wilson, H R

2006-01-01

The boundary of the tokamak core plasma, or scrape-off layer, is normally characterized in terms of average parameters such as density, temperature and e-folding lengths suggesting diffusive losses. However, as is shown in this paper, localized filamentary structures play an important role in determining the radial efflux in both L mode and during edge localized modes (ELMs) on MAST. Understanding the size, poloidal and toroidal localization and the outward radial extent of these filaments is crucial in order to calculate their effect on power loading both on the first wall and the divertor target plates in future devices. The spatial and temporal evolution of filaments observed on MAST in L-mode and ELMs have been compared and contrasted in order to confront the predictions of various models that have been proposed to predict filament propagation and in particular ELM energy losses

A Survery of the Correlation between Filament Chirality and Sigmoid Handedness

Science.gov (United States)

V, A.; Hazra, S.; Martin, S. F.; Martens, P. C.

2017-12-01

Sigmoid regions on the Sun are often the regions that cause Coronal Mass Ejections (CMEs). Large CMEs most often have filaments that erupt with them. This study focuses on the statistical relevance of the shape of the sigmoid and the chirality of the filament residing in these sigmoids. The study further extends to the relation between the directionality of filaments and the Earth-directed CMEs. Sigmoid data from Savcheva et al. (2014) between 2007 and 2012 and a compilation of data using the HEK Sigmoid Sniffer (Martens et al. 2012) along with Hinode XRT Soft X-ray images were used for analyzing data between 2013 and 2017. Hence this dataset consists of almost one solar cycle of data. A similar study done previously by Martens et al. (2013) analysed data for a solar cycle using an Advanced Automated Filament Detection & Characterization Code (Bernasconi, Rust & Hakim 2005). Considering that automated chirality detection is not foolproof, we present this study which uses manual determination of chirality for accuracy using high resolution chromospheric images. Mainly full disk images of soft X-ray obtained from Hinode XRT (X-Ray Telescope) have been used to find and ensure the S or Z shape of sigmoids. H-alpha images obtained from BBSO and Kanzelhohe Solar Observatory (KSO) are used in determining the chirality of filaments. The resolutions of BBSO and KSO data are 1k and 4k respectively. A comparison of the analysis of the chirality of filaments using both data will be presented. Although KSO gives a 4k resolution, it is still difficult to determine the chirality of small filaments. For this reason, high resolution images of H-alpha chromospheric filaments obtained from Helio Research and Solar Observing Optical Network (SOON) have been used for further analysis of chirality of those filaments that were undeterminable using the BBSO or KSO full disk images. The results of the comparison using the different resolutions are shown. The results of the correlation

An intermediate level of CD161 expression defines a novel activated, inflammatory, and pathogenic subset of CD8+ T cells involved in multiple sclerosis.

Science.gov (United States)

Nicol, Bryan; Salou, Marion; Vogel, Isabel; Garcia, Alexandra; Dugast, Emilie; Morille, Jeremy; Kilens, Stéphanie; Charpentier, Eric; Donnart, Audrey; Nedellec, Steven; Jacq-Foucher, Marylène; Le Frère, Fabienne; Wiertlewski, Sandrine; Bourreille, Arnaud; Brouard, Sophie; Michel, Laure; David, Laurent; Gourraud, Pierre-Antoine; Degauque, Nicolas; Nicot, Arnaud B; Berthelot, Laureline; Laplaud, David-Axel

2018-03-01

Several lines of evidence support a key role for CD8 + T cells in central nervous system tissue damage of patients with multiple sclerosis. However, the precise phenotype of the circulating CD8 + T cells that may be recruited from the peripheral blood to invade the CNS remains largely undefined to date. It has been suggested that IL-17 secreting CD8 (Tc17) T cells may be involved, and in humans these cells are characterized by the expression of CD161. We focused our study on a unique and recently described subset of CD8 T cells characterized by an intermediate expression of CD161 as its role in neuroinflammation has not been investigated to date. The frequency, phenotype, and function of CD8 + T cells with an intermediate CD161 expression level were characterized ex-vivo, in vitro, and in situ using RNAseq, RT-PCR, flow cytometry, TCR sequencing, and immunohistofluorescence of cells derived from healthy volunteers (n = 61), MS subjects (n = 90), as well as inflammatory (n = 15) and non-inflammatory controls (n = 6). We report here that CD8 + CD161 int T cells present characteristics of effector cells, up-regulate cell-adhesion molecules and have an increased ability to cross the blood-brain barrier and to secrete IL-17, IFNγ, GM-CSF, and IL-22. We further demonstrate that these cells are recruited and enriched in the CNS of MS subjects where they produce IL-17. In the peripheral blood, RNAseq, RT-PCR, high-throughput TCR repertoire analyses, and flow cytometry confirmed an increased effector and transmigration pattern of these cells in MS patients, with the presence of supernumerary clones compared to healthy controls. Our data demonstrate that intermediate levels of CD161 expression identifies activated and effector CD8 + T cells with pathogenic properties that are recruited to MS lesions. This suggests that CD161 may represent a biomarker and a valid target for the treatment of neuroinflammation. Copyright © 2017 The Authors. Published by Elsevier Ltd

Filament supply circuit for particle accelerator

International Nuclear Information System (INIS)

Thompson, C.C. Jr.; Malone, H.F.

1975-01-01

In a particle accelerator of the type employing ac primary power and a voltage multiplication apparatus to achieve the required high dc accelerating voltage, a filament supply circuit is powered by a portion of the ac primary power appearing at the last stage of the voltage multiplier. This ac power is applied across a voltage regulator circuit in the form of two zener diodes connected back to back. The threshold of the zeners is below the lowest peak-to-peak voltage of the ac voltage, so that the regulated voltage remains constant for all settings of the adjustable acceleration voltage. The regulated voltage is coupled through an adjustable resistor and an impedance-matching transformer to the accelerator filament. (auth)

Calcium binding to an elastic portion of connectin/titin filaments.

Science.gov (United States)

Tatsumi, R; Maeda, K; Hattori, A; Takahashi, K

2001-01-01

Alpha-connectin/titin-1 exists as an elastic filament that links a thick filament with the Z-disk, keeping thick filaments centered within the sarcomere during force generation. We have shown that the connectin filament has an affinity for calcium ions and its binding site(s) is restricted to the beta-connectin/titin-2 portion. We now report the localization and the characterization of calcium-binding sites on beta-connectin. Purified beta-connectin was digested by trypsin into 1700- and 400-kDa fragments. which were then subjected to fluorescence calcium-binding assays. The 400-kDa fragment possesses calcium-binding activity; the binding constant was 1.0 x 10(7) M(-1) and the molar ratio of bound calcium ions to the 400-kDa fragment reached a maximum of 12 at a free calcium ion concentration of approximately 1.0 microM. Antibodies against the 400-kDa fragment formed a sharp dense stripe at the boundary of the A and the I bands, indicating that the calcium-binding domain constitutes the N-terminal region of beta-connectin, that is, the elastic portion of connectin filaments. Furthermore, we estimated the N-terminal location of beta-connectin of various origins (n = 26). Myofibrils were treated with a solution containing 0.1 mM CaCl2 and 70 microM leupeptin to split connectin filaments into beta-connectin and a subfragment, and chain weights of these polypeptides were estimated according to their mobility in 2% polyacrylamide slab gels. The subfragment exhibited a similar chain weight of 1200+/-33 kDa (mean+/-SD), while alpha- and beta-connectins were variable in size according to their origin. These results suggest that the apparent length of the 1200-kDa subfragment portion is almost constant in all instances, about 0.34 microm at the slack condition, therefore that the C-terminus of the 1200-kDa subfragment, that is, the N-terminus of the calcium-binding domain, is at the N2 line region of parent filaments in situ. Because the secondary structure of the 400-k

Forchlorfenuron disrupts SEPT9_i1 filaments and inhibits HIF-1.

Directory of Open Access Journals (Sweden)

Dikla Vardi-Oknin

Full Text Available Forchlorfenuron (FCF is a synthetic plant cytokinin that has been shown to alter yeast and mammalian septin organization. Septins are a highly conserved family of GTP-binding cytoskeletal proteins. Mammalian septins are involved in diverse cellular processes including tumorigenesis. We have been studying the interaction between septin 9 isoform 1 (SEPT9_i1 and hypoxia inducible factor-1α (HIF-1α, the oxygen regulated subunit of HIF-1. HIF-1 is a key transcription factor in the hypoxic responses pathway, and its activation has been observed in carcinogenesis and numerous cancers. SEPT9_i1/HIF-1α interaction plays an important role in upregulation of HIF-1 transcriptional activity by preventing HIF-1α's ubiquitination and degradation leading to increased tumor growth and angiogenesis. We tested the hypothesis whether FCF affects SEPT9_i1 filamentous structures and consequently HIF-1 pathway in cancer cells. We showed that FCF suppresses tumorigenic properties, including proliferation, migration and transformation, in prostate cancer cells. FCF did not alter SEPT9_i1 steady state protein expression levels but it affected its filamentous structures and subcellular localization. FCF induced degradation of HIF-1α protein in a dose- and time-dependent manner. This inhibition was also shown in other common cancer types tested. Rapid degradation of HIF-1α protein levels was accompanied by respective inhibition in HIF-1α transcriptional activity. Moreover, HIF-1α protein half-life was markedly decreased in the presence of FCF compared with that in the absence of FCF. The FCF-induced degradation of HIF-1α was mediated in a significant part via the proteasome. To the best of our knowledge, this is the first demonstration of specific manipulation of septin filaments by pharmacological means having downstream inhibitory effects on the HIF-1 pathway.

Filamentous hydrous ferric oxide biosignatures in a pipeline carrying acid mine drainage at Iron Mountain Mine, California

Science.gov (United States)

Williams, Amy J.; Alpers, Charles N.; Sumner, Dawn Y.; Campbell, Kate M.

2017-01-01

A pipeline carrying acidic mine effluent at Iron Mountain, CA, developed Fe(III)-rich precipitate caused by oxidation of Fe(II)aq. The native microbial community in the pipe included filamentous microbes. The pipe scale consisted of microbial filaments, and schwertmannite (ferric oxyhydroxysulfate, FOHS) mineral spheres and filaments. FOHS filaments contained central lumina with diameters similar to those of microbial filaments. FOHS filament geometry, the geochemical environment, and the presence of filamentous microbes suggest that FOHS filaments are mineralized microbial filaments. This formation of textural biosignatures provides the basis for a conceptual model for the development and preservation of biosignatures in other environments.

Video-supported analysis of Beggiatoa filament growth, breakage, and movement

DEFF Research Database (Denmark)

Kamp, Anja; Røy, Hans; Schulz-Vogt, Heide N.

2008-01-01

A marine Beggiatoa sp. was cultured in semi-solid agar with opposing oxygen-sulfide gradients. Growth pattern, breakage of filaments for multiplication, and movement directions of Beggiatoa filaments in the transparent agar were investigated by time-lapse video recording. The initial doubling time...

A control scheme for filament stretching rheometers with application to polymer melts

DEFF Research Database (Denmark)

Román Marín, José Manuel; Huusom, Jakob Kjøbsted; Javier Alvarez, Nicolas

2013-01-01

We propose a new control scheme to maintain a constant strain rate of the mid-filament diameter in a filament stretching rheometer for polymer melts. The scheme is cast as a velocity algorithm and consists of a feed-back and a feed-forward contribution. The performance of the controller is demons......We propose a new control scheme to maintain a constant strain rate of the mid-filament diameter in a filament stretching rheometer for polymer melts. The scheme is cast as a velocity algorithm and consists of a feed-back and a feed-forward contribution. The performance of the controller...

OSCILLATING FILAMENTS. I. OSCILLATION AND GEOMETRICAL FRAGMENTATION

Energy Technology Data Exchange (ETDEWEB)

Gritschneder, Matthias; Heigl, Stefan; Burkert, Andreas, E-mail: gritschm@usm.uni-muenchen.de [University Observatory Munich, LMU Munich, Scheinerstrasse 1, D-81679 Munich (Germany)

2017-01-10

We study the stability of filaments in equilibrium between gravity and internal as well as external pressure using the grid-based AMR code RAMSES. A homogeneous, straight cylinder below a critical line mass is marginally stable. However, if the cylinder is bent, such as with a slight sinusoidal perturbation, an otherwise stable configuration starts to oscillate, is triggered into fragmentation, and collapses. This previously unstudied behavior allows a filament to fragment at any given scale, as long as it has slight bends. We call this process “geometrical fragmentation.” In our realization, the spacing between the cores matches the wavelength of the sinusoidal perturbation, whereas up to now, filaments were thought to be only fragmenting on the characteristic scale set by the mass-to-line ratio. Using first principles, we derive the oscillation period as well as the collapse timescale analytically. To enable a direct comparison with observations, we study the line-of-sight velocity for different inclinations. We show that the overall oscillation pattern can hide the infall signature of cores.

Filament structure, organization, and dynamics in MreB sheets.

Science.gov (United States)

Popp, David; Narita, Akihiro; Maeda, Kayo; Fujisawa, Tetsuro; Ghoshdastider, Umesh; Iwasa, Mitsusada; Maéda, Yuichiro; Robinson, Robert C

2010-05-21

In vivo fluorescence microscopy studies of bacterial cells have shown that the bacterial shape-determining protein and actin homolog, MreB, forms cable-like structures that spiral around the periphery of the cell. The molecular structure of these cables has yet to be established. Here we show by electron microscopy that Thermatoga maritime MreB forms complex, several mum long multilayered sheets consisting of diagonally interwoven filaments in the presence of either ATP or GTP. This architecture, in agreement with recent rheological measurements on MreB cables, may have superior mechanical properties and could be an important feature for maintaining bacterial cell shape. MreB polymers within the sheets appear to be single-stranded helical filaments rather than the linear protofilaments found in the MreB crystal structure. Sheet assembly occurs over a wide range of pH, ionic strength, and temperature. Polymerization kinetics are consistent with a cooperative assembly mechanism requiring only two steps: monomer activation followed by elongation. Steady-state TIRF microscopy studies of MreB suggest filament treadmilling while high pressure small angle x-ray scattering measurements indicate that the stability of MreB polymers is similar to that of F-actin filaments. In the presence of ADP or GDP, long, thin cables formed in which MreB was arranged in parallel as linear protofilaments. This suggests that the bacterial cell may exploit various nucleotides to generate different filament structures within cables for specific MreB-based functions.

Mechanical behaviors of multi-filament twist superconducting strand under tensile and cyclic loading

Science.gov (United States)

Wang, Xu; Li, Yingxu; Gao, Yuanwen

2016-01-01

The superconducting strand, serving as the basic unit cell of the cable-in-conduit-conductors (CICCs), is a typical multi-filament twist composite which is always subjected to a cyclic loading under the operating condition. Meanwhile, the superconducting material Nb3Sn in the strand is sensitive to strain frequently relating to the performance degradation of the superconductivity. Therefore, a comprehensive study on the mechanical behavior of the strand helps understanding the superconducting performance of the strained Nb3Sn strands. To address this issue, taking the LMI (internal tin) strand as an example, a three-dimensional structural finite element model, named as the Multi-filament twist model, of the strand with the real configuration of the LMI strand is built to study the influences of the plasticity of the component materials, the twist of the filament bundle, the initial thermal residual stress and the breakage and its evolution of the filaments on the mechanical behaviors of the strand. The effective properties of superconducting filament bundle with random filament breakage and its evolution versus strain are obtained based on the damage theory of fiber-reinforced composite materials proposed by Curtin and Zhou. From the calculation results of this model, we find that the occurrence of the hysteresis loop in the cyclic loading curve is determined by the reverse yielding of the elastic-plastic materials in the strand. Both the initial thermal residual stress in the strand and the pitch length of the filaments have significant impacts on the axial and hysteretic behaviors of the strand. The damage of the filaments also affects the axial mechanical behavior of the strand remarkably at large axial strain. The critical current of the strand is calculated by the scaling law with the results of the Multi-filament twist model. The predicted results of the Multi-filament twist model show an acceptable agreement with the experiment.

Multiple large filament bundles observed in Caulobacter crescentus by electron cryotomography

DEFF Research Database (Denmark)

Briegel, A; Dias, DP; Li, Z

2006-01-01

While the absence of any cytoskeleton was once recognized as a distinguishing feature of prokaryotes, it is now clear that a number of different bacterial proteins do form filaments in vivo. Despite the critical roles these proteins play in cell shape, genome segregation and cell division...... on shape and location, referred to here as 'inner curvature', 'cytoplasmic', 'polar' and 'ring-like'. In an attempt to identify at least some of the filaments, we imaged cells where crescentin and MreB filaments would not be present. The inner curvature and cytoplasmic bundles persisted, which together...... with their localization patterns, suggest that they are composed of as-yet unidentified cytoskeletal proteins. Thus bacterial filaments are frequently found as bundles, and their variety and abundance is greater than previously suspected....

THE SPIN AND ORIENTATION OF DARK MATTER HALOS WITHIN COSMIC FILAMENTS

International Nuclear Information System (INIS)

Zhang Youcai; Yang Xiaohu; Lin Weipeng; Faltenbacher, Andreas; Springel, Volker; Wang Huiyuan

2009-01-01

Clusters, filaments, sheets, and voids are the building blocks of the cosmic web. Forming dark matter halos respond to these different large-scale environments, and this in turn affects the properties of galaxies hosted by the halos. It is therefore important to understand the systematic correlations of halo properties with the morphology of the cosmic web, as this informs both about galaxy formation physics and possible systematics of weak lensing studies. In this study, we present and compare two distinct algorithms for finding cosmic filaments and sheets, a task which is far less well established than the identification of dark matter halos or voids. One method is based on the smoothed dark matter density field and the other uses the halo distributions directly. We apply both techniques to one high-resolution N-body simulation and reconstruct the filamentary/sheet like network of the dark matter density field. We focus on investigating the properties of the dark matter halos inside these structures, in particular, on the directions of their spins and the orientation of their shapes with respect to the directions of the filaments and sheets. We find that both the spin and the major axes of filament halos with masses ∼ 13 h -1 M sun are preferentially aligned with the direction of the filaments. The spins and major axes of halos in sheets tend to lie parallel to the sheets. There is an opposite mass dependence of the alignment strength for the spin (negative) and major (positive) axes, i.e. with increasing halo mass the major axis tends to be more strongly aligned with the direction of the filament, whereas the alignment between halo spin and filament becomes weaker with increasing halo mass. The alignment strength as a function of the distance to the most massive node halo indicates that there is a transit large-scale environment impact: from the two-dimensional collapse phase of the filament to the three-dimensional collapse phase of the cluster/node halo at

The Spin and Orientation of Dark Matter Halos Within Cosmic Filaments

Science.gov (United States)

Zhang, Youcai; Yang, Xiaohu; Faltenbacher, Andreas; Springel, Volker; Lin, Weipeng; Wang, Huiyuan

2009-11-01

Clusters, filaments, sheets, and voids are the building blocks of the cosmic web. Forming dark matter halos respond to these different large-scale environments, and this in turn affects the properties of galaxies hosted by the halos. It is therefore important to understand the systematic correlations of halo properties with the morphology of the cosmic web, as this informs both about galaxy formation physics and possible systematics of weak lensing studies. In this study, we present and compare two distinct algorithms for finding cosmic filaments and sheets, a task which is far less well established than the identification of dark matter halos or voids. One method is based on the smoothed dark matter density field and the other uses the halo distributions directly. We apply both techniques to one high-resolution N-body simulation and reconstruct the filamentary/sheet like network of the dark matter density field. We focus on investigating the properties of the dark matter halos inside these structures, in particular, on the directions of their spins and the orientation of their shapes with respect to the directions of the filaments and sheets. We find that both the spin and the major axes of filament halos with masses lsim1013 h -1 M sun are preferentially aligned with the direction of the filaments. The spins and major axes of halos in sheets tend to lie parallel to the sheets. There is an opposite mass dependence of the alignment strength for the spin (negative) and major (positive) axes, i.e. with increasing halo mass the major axis tends to be more strongly aligned with the direction of the filament, whereas the alignment between halo spin and filament becomes weaker with increasing halo mass. The alignment strength as a function of the distance to the most massive node halo indicates that there is a transit large-scale environment impact: from the two-dimensional collapse phase of the filament to the three-dimensional collapse phase of the cluster/node halo at

Tyrosine kinase signalling in breast cancer: Modulation of tyrosine kinase signalling in human breast cancer through altered expression of signalling intermediates

International Nuclear Information System (INIS)

Kairouz, Rania; Daly, Roger J

2000-01-01

The past decade has seen the definition of key signalling pathways downstream of receptor tyrosine kinases (RTKs) in terms of their components and the protein-protein interactions that facilitate signal transduction. Given the strong evidence that links signalling by certain families of RTKs to the progression of breast cancer, it is not surprising that the expression profile of key downstream signalling intermediates in this disease has also come under scrutiny, particularly because some exhibit transforming potential or amplify mitogenic signalling pathways when they are overexpressed. Reflecting the diverse cellular processes regulated by RTKs, it is now clear that altered expression of such signalling proteins in breast cancer may influence not only cellular proliferation (eg Grb2) but also the invasive properties of the cancer cells (eg EMS1/cortactin)

Growth and nitrate reduction of Beggiatoa filaments studied in enrichment cultures

DEFF Research Database (Denmark)

Kamp, Anja

In this thesis, several aspects of the gliding, filamentous, colourless sulphur bacteria Beggiatoa were investigated. The first part of this thesis addressed the growth mode, breakage of filaments for multiplication, and movement directions of filaments of Beggiatoa. Marine Beggiatoa were enriche...... to ammonium), whereas denitrification was not detected. This study revealed for the first time that a freshwater Beggiatoa strain was capable of intracellular accumulation of nitrate, and that the nitrate was used to perform DNRA....

Comments on filament-disintegration and its relation to other aspects of solar activity.

Science.gov (United States)

Dodson, H. W.; Hedeman, E. R.; Rovira De Miceli, M.

1972-01-01

Studies of sudden disintegrations of filaments in solar cycles 19 and 20 (to 1969) indicate that such events occur frequently. Approximately 30% of all large filaments in these cycles disintegrated in the course of their transit across the solar disk. 'Major' flares occurred with above average frequency on the last day on which 141 large disappearing filaments were observed. Relationships between a disintegrating filament on July 10-11, 1959, a prior major flare, a newly formed spot, and concomitant growth of H-alpha plage are presented. Observation of prior descending prominence material apparently directed towards the location of the flare of July 15, 1959 is reported. The development of the filament-associated flare of Feb. 13, 1967 is described.

Extension of filament propagation in water with Bessel-Gaussian beams

Energy Technology Data Exchange (ETDEWEB)

Kaya, G.; Sayrac, M.; Boran, Y.; Kolomenskii, A. A. [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); Kaya, N.; Schuessler, H. A. [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); Science and Petroleum, Texas A& M University at Qatar, Doha 23874 (Qatar); Strohaber, J. [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); Department of Physics, Florida A& M University, Tallahassee, Florida 32307 (United States); Amani, M. [Science and Petroleum, Texas A& M University at Qatar, Doha 23874 (Qatar)

2016-03-15

We experimentally studied intense femtosecond pulse filamentation and propagation in water for Bessel-Gaussian beams with different numbers of radial modal lobes. The transverse modes of the incident Bessel-Gaussian beam were created from a Gaussian beam of a Ti:sapphire laser system by using computer generated hologram techniques. We found that filament propagation length increased with increasing number of lobes under the conditions of the same peak intensity, pulse duration, and the size of the central peak of the incident beam, suggesting that the radial modal lobes may serve as an energy reservoir for the filaments formed by the central intensity peak.

Manipulation by multiple filamentation of subpicosecond TW KrF laser beam

Science.gov (United States)

Zvorykin, V. D.; Smetanin, I. V.; Ustinovskii, N. N.; Shutov, A. V.

2018-05-01

A self-focusing of TW-level subpicosecond UV KrF laser pulses in ambient air produces a few 100 randomly distributed filaments over 100-m propagation distance. A control of multiple filamentation process by a number of methods was demonstrated in the present work envisaging applications for a HV discharge guiding, remote excitation of an atmospheric air laser, MW radiation transfer by virtual plasma waveguide, as well as filamentation suppression to improve short pulse parameters in direct amplification scheme. Under the laser beam focusing, a multitude of filaments coalesced into a superfilament with highly increased intensity and plasma conductivity. A superradiant forward lasing was obtained in the superfilament around 1.07-µm wavelength of atmospheric nitrogen. A regular 2D array of a 100 superfilaments was configured over 20-m distance by Fresnel diffraction on periodic amplitude masks. Effective Kerr defocusing and a subsequent filaments suppression over 50-m distance was demonstrated in Xe due to 2-photon resonance of laser radiation with 6p state being accompanied by a narrow-angle coherent conical emission at 828-nm wavelength.

Capillary thinning of polymeric filaments

DEFF Research Database (Denmark)

Kolte, Mette Irene; Szabo, Peter

1999-01-01

The capillary thinning of filaments of a Newtonian polybutene fluid and a viscoelastic polyisobutylene solution are analyzed experimentally and by means of numerical simulation. The experimental procedure is as follows. Initially, a liquid sample is placed between two cylindrical plates. Then, th...

Magnetic tension and instabilities in the Orion A integral-shaped filament

Science.gov (United States)

Schleicher, Dominik R. G.; Stutz, Amelia

2018-03-01

The Orion nebula is a prime example of a massive star-forming region in our galaxy. Observations have shown that gravitational and magnetic energy are comparable in its integral-shaped filament on a scale of ˜1 pc, and that the population of pre-main sequence stars appears dynamically heated compared to the protostars. These results have been attributed to a slingshot mechanism resulting from the oscillation of the filament by Stutz & Gould. In this paper, we show that radially contracting filaments naturally evolve towards a state where gravitational, magnetic, and rotational energy are comparable. While the contraction of the filament will preferentially amplify the axial component of the magnetic field, the presence of rotation leads to a helical field structure. We show how magnetic tension can give rise to a filament oscillation, and estimate a typical time-scale of 0.7 Myr for the motion of the filament to the position of maximum displacement, consistent with the characteristic time-scale of the ejected stars. Furthermore, the presence of helical magnetic fields is expected to give rise to magneto-hydrodynamical instabilities. We show here that the presence of a magnetic field significantly enhances the overall instability, which operates on a characteristic scale of about 1 pc. We expect the physics discussed here to be generally relevant in massive star-forming regions, and encourage further investigations in the future.

On the association of magnetic clouds with disappearing filaments

International Nuclear Information System (INIS)

Wilson, R.M.; Hildner, E.

1986-01-01

We present evidence that an interplanetary magnetic cloud preceding an interaction region, observed at earth January 24, 1974, is associated with the eruptive filament or disparition brusque (DB) near central meridian on January 18. The DB also was associated with a long-decay soft X ray transient (LDE) and a long-duration gradual-rise-and-fall (GRF) radio burst. To assess whether magnetic clouds are generally associated with DBs, we present results from statistical testing of the relation of 33 magnetic clouds (and 33 control samples without magnetic clouds) to disappearing filaments near central meridian (approx. 99% confidence. There is a suggestion that clouds following shocks, probably launched at times of solar flares, are not as strongly associated with disappearing filaments as are clouds launched less violently

Strength analysis of filament-wound composite tubes

Directory of Open Access Journals (Sweden)

Vasović Ivana

2010-01-01

Full Text Available The subject of this work is focused on strength analysis of filament-wound composite tubes made of E glass/polyester under internal pressure. The primary attention of this investigation is to develop a reliable computation procedure for stress, displacement and initial failure analysis of layered composite tubes. For that purpose we have combined the finite element method (FEM with corresponding initial failure criterions. In addition, finite element analyses using commercial code, MSC/NASTRAN, were performed to predict the behavior of filament wound structures. Computation results are compared with experiments. Good agreement between computation and experimental results are obtained.

Infrared Radiation Filament And Metnod Of Manufacture

Science.gov (United States)

Johnson, Edward A.

1998-11-17

An improved IR radiation source is provided by the invention. A radiation filament has a textured surface produced by seeded ion bombardment of a metal foil which is cut to a serpentine shape and mounted in a windowed housing. Specific ion bombardment texturing techniques tune the surface to maximize emissions in the desired wavelength range and to limit emissions outside that narrow range, particularly at longer wavelengths. A combination of filament surface texture, thickness, material, shape and power circuit feedback control produce wavelength controlled and efficient radiation at much lower power requirements than devices of the prior art.

Elastic deformation and failure in protein filament bundles: Atomistic simulations and coarse-grained modeling.

Science.gov (United States)

Hammond, Nathan A; Kamm, Roger D

2008-07-01

The synthetic peptide RAD16-II has shown promise in tissue engineering and drug delivery. It has been studied as a vehicle for cell delivery and controlled release of IGF-1 to repair infarcted cardiac tissue, and as a scaffold to promote capillary formation for an in vitro model of angiogenesis. The structure of RAD16-II is hierarchical, with monomers forming long beta-sheets that pair together to form filaments; filaments form bundles approximately 30-60 nm in diameter; branching networks of filament bundles form macroscopic gels. We investigate the mechanics of shearing between the two beta-sheets constituting one filament, and between cohered filaments of RAD16-II. This shear loading is found in filament bundle bending or in tensile loading of fibers composed of partial-length filaments. Molecular dynamics simulations show that time to failure is a stochastic function of applied shear stress, and that for a given loading time behavior is elastic for sufficiently small shear loads. We propose a coarse-grained model based on Langevin dynamics that matches molecular dynamics results and facilities extending simulations in space and time. The model treats a filament as an elastic string of particles, each having potential energy that is a periodic function of its position relative to the neighboring filament. With insight from these simulations, we discuss strategies for strengthening RAD16-II and similar materials.

The L1495-B218 filaments in Taurus seen in NH3 & CCS and Dynamical Stability of Filaments and Dense Cores

Science.gov (United States)

Seo, Youngmin

2016-01-01

We present deep NH3 map of L1495-B218 filaments and the dense cores embedded within the filaments in Taurus. The L1495-B218 filaments form an interconnected, nearby, large complex extending 8 pc. We observed the filaments in NH3 (1,1) & (2,2) and CCS 21-10 with spectral resolution of 0.038 km/s and spatial resolution of 31". The CSAR algorithm, which is a hybrid of seeded-watershed and binary dendrogram algorithm, identifies 39 leaves and 16 branches in NH3 (1,1). Applying a virial analysis for the 39 NH3 leaves, we find only 9 out of 39 leaves are gravitationally bound, and 12 out of 30 gravitationally unbound leaves are pressure-confined. Our analysis suggests that a dense core may form as a pressure-confined structure, evolve to a gravitationally bound core, and then undergo collapse to form a protostar (Seo et al. 2015).We also present more realistic dynamic stability conditions for dense cores with converging motions and under the influence of radiation pressure. The critical Bonnor-Ebert sphere and the isothermal cylinder have been widely used to test stability of dense cores and filaments; however, these assume a quiescent environment while actual star forming regions are turbulent and illuminated by radiation. In a new analysis of stability conditions we account for converging motions which have been modeled toward starless cores (Seo et al. 2011) and the effect of radiation fields into account. We find that the critical size of a dense core having a homologous converging motion with its peak speed being the sound speed is roughly half of the critical size of the Bonnor-Ebert sphere (Seo et al. 2013). We also find that the critical mass/line density of a dense core/filament irradiated by radiation are considerably smaller than that of the Bonnor-Ebert sphere/isothermal cylinder when the radiation pressure is stronger than the central gas pressure of dense core/isothermal cylinder. For inner Galactic regions and regions near OB associations, the critical

Evaluation of filamentous green algae as feedstocks for biofuel production.

Science.gov (United States)

Zhang, Wei; Zhao, Yonggang; Cui, Binjie; Wang, Hui; Liu, Tianzhong

2016-11-01

Compared with unicellular microalgae, filamentous algae have high resistance to grazer-predation and low-cost recovery in large-scale production. Green algae, as the most diverse group of algae, included numerous filamentous genera and species. In this study, records of filamentous genera and species in green algae were firstly censused and classified. Then, seven filamentous strains subordinated in different genera were cultivated in bubbled-column to investigate their growth rate and energy molecular (lipid and starch) capacity. Four strains including Stigeoclonium sp., Oedogonium nodulosum, Hormidium sp. and Zygnema extenue were screened out due to their robust growth. And they all could accumulate triacylglycerols and starch in their biomass, but with different capacity. After nitrogen starvation, Hormidium sp. and Oedogonium nodulosum respectively exhibited high capacity of lipid (45.38% in dry weight) and starch (46.19% in dry weight) accumulation, which could be of high potential as feedstocks for biodiesel and bioethanol production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fossil evidence for spin alignment of Sloan Digital Sky Survey galaxies in filaments

NARCIS (Netherlands)

Jones, Bernard J. T.; van de Weijgaert, Marinus; Aragon-Calvo, Miguel A.

2010-01-01

We search for and find fossil evidence that the spin axes of galaxies in cosmic web filaments relative to their host filaments are not randomly distributed. This indicates the fact that the action of large-scale tidal torques affected the alignments of galaxies located in cosmic filaments. To this

Collapsing vortex filaments and the spectrum of quantum turbulence

Science.gov (United States)

Andryushchenko, V. A.; Nemirovskii, S. K.

2017-01-01

The method of correlation functions and the method of quantum vortex configurations are used to calculate the energy spectrum of a three-dimensional velocity field that is induced by collapsing (immediately before reconnection) vortex filaments. The formulation of this problem is motivated by the idea of modeling classical turbulence by a set of chaotic quantized vortex filaments. Among the various arguments that support the idea of quasi-classical behavior for quantum turbulence, the most persuasive is probably the resulting Kolmogorov energy spectrum resembling E ( k ) ∝ k - 5 / 3 that was obtained in a number of numerical studies. Another goal is associated with an important and intensely studied theme that relates to the role of hydrodynamic collapse in the formation of turbulence spectra. Calculations have demonstrated that vortex filaments create a velocity field at the moment of contact, which has a singularity. This configuration of vortex filaments generates the spectrum E(k), which bears the resemblance to the Kolmogorov law. A possible cause for this observation is discussed, as well as the likely reasons behind any deviations. The obtained results are discussed from the perspective of both classical and quantum turbulence.

Electron emission regulator for an x-ray tube filament

International Nuclear Information System (INIS)

Daniels, H.E.; Randall, H.G.

1982-01-01

An x-ray tube ma regulator has an scr phase shift voltage regulator supplying the primary winding of a transformer whose secondary is coupled to the x-ray tube filament. Prior to initiation of an x-ray exposure, the filament is preheated to a temperature corresponding substantially to the electron emissivity needed for obtaining the desired tube ma during an exposure. During the preexposure interval, the phase shift regulator is controlled by a signal corresponding to the sum of signals representative of the voltage applied to the filament transformer, the desired filament voltage and the space charge compensation needed for the selected x-ray tube anode to cathode voltage. When an exposure is initiated, control of the voltage regulator is switched to a circuit that responds to the tube current by controlling the amount of phase shift and, hence, the voltage supplied to the transformer. Transformer leakage current compensation is provided during the exposure interval with a circuit that includes an element whose impedance is varied in accordance with the anode-to-cathode voltage setting so the element drains off tube current as required to cancel the effect of leakage current variations

The circulation dynamics associated with a northern Benguela upwelling filament during October 2010

Science.gov (United States)

Muller, Annethea A.; Mohrholz, Volker; Schmidt, Martin

2013-07-01

Upwelling filaments, a common feature in all the major upwelling systems, are also regularly observed in the Benguela upwelling system and are thought to provide an effective mechanism for the exchange of matter between the shelf and the open ocean. The mesoscale dynamics of a northern Benguela upwelling filament located at approximately 18.5°S were examined and the associated transport was quantified. The development of the filament was tracked using optimal interpolated SST satellite data and two transects were consequently sampled across the feature using a towed undulating CTD (ScanFish). Additional hydrographic, nutrient and biological parameters were investigated at several stations along each transect. Following 7 days of strong upwelling favorable winds, sampling coincided with a period of relative wind relaxation and the filament was presumably in a decaying state. The basic mesoscale structure of the investigated filament corresponded well to what had previously been described for filaments from other eastern boundary current systems. The cross-shore transport associated with the filament was found to be significantly greater than the integrated Ekman transport in the region. With the combination of the high resolution dataset and a MOM-4 ecosystem model the complex mesoscale flow field associated with the feature could be observed and the counterbalancing onshore transport, associated with subsurface dipole eddies, was revealed within the filament. The results further suggest that an interaction between the offshore bending of flow at the Angola-Benguela Front (ABF), the detachment of the strong poleward flow from the coast as the thermal front meanders and the observed dipole eddies may be driving filament occurrence in the region off Cape Frio.

Fossil evidence for spin alignment of SDSS galaxies in filaments

NARCIS (Netherlands)

Jones, Bernard J.T.; Weygaert, Rien van de; Arag´on-Calvo, Miguel A.

2010-01-01

We search for and find fossil evidence that the distribution of the spin axes of galaxies in cosmic web filaments relative to their host filaments are not randomly distributed. This would indicate that the action of large scale tidal torques effected the alignments of galaxies located in cosmic

Transient filament stretching rheometer II

DEFF Research Database (Denmark)

Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

1997-01-01

The Lagrangian sspecification is used to simulate the transient stretching filament rheometer. Simulations are performed for dilute PIB-solutions modeled as a four mode Oldroyd-B fluid and a semidilute PIB-solution modeled as a non-linear single integral equation. The simulations are compared...

Filament Winding. A Unified Approach

NARCIS (Netherlands)

Koussios, S.

2004-01-01

In this dissertation we have presented an overview and comprehensive treatment of several facets of the filament winding process. With the concepts of differential geometry and the theory of thin anisotropic shells of revolution, a parametric shape generator has been formulated for the design

THE CONTRACTION OF OVERLYING CORONAL LOOP AND THE ROTATING MOTION OF A SIGMOID FILAMENT DURING ITS ERUPTION

Energy Technology Data Exchange (ETDEWEB)

Yan, X. L.; Qu, Z. Q.; Xue, Z. K.; Deng, L. H.; Ma, L.; Kong, D. F. [National Astronomical Observatories/Yunnan Astronomical Observatory, Chinese Academy of Sciences, Kunming 650011 (China); Pan, G. M. [College of Mathematics Physics and Information Engineering, Jiaxing University, Jiaxing 314001 (China); Liu, J. H. [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2013-06-15

We present an observation of overlying coronal loop contraction and rotating motion of the sigmoid filament during its eruption on 2012 May 22 observed by the Solar Dynamics Observatory (SDO). Our results show that the twist can be transported into the filament from the lower atmosphere to the higher atmosphere. The successive contraction of the coronal loops was due to a suddenly reduced magnetic pressure underneath the filament, which was caused by the rising of the filament. Before the sigmoid filament eruption, there was a counterclockwise flow in the photosphere at the right feet of the filament and the contraction loops and a convergence flow at the left foot of the filament. The hot and cool materials have inverse motion along the filament before the filament eruption. Moreover, two coronal loops overlying the filament first experienced brightening, expansion, and contraction successively. At the beginning of the rising and rotation of the left part of the filament, the second coronal loop exhibited rapid contraction. The top of the second coronal loop also showed counterclockwise rotation during the contraction process. After the contraction of the second loop, the left part of the filament rotated counterclockwise and expanded toward the right of NOAA AR 11485. During the filament expansion, the right part of the filament also exhibited counterclockwise rotation like a tornado.

PARTIAL ERUPTION OF A FILAMENT WITH TWISTING NON-UNIFORM FIELDS

International Nuclear Information System (INIS)

Bi, Yi; Jiang, Yunchun; Yang, Jiayan; Xiang, Yongyuan; Cai, Yunfang; Liu, Weiwei

2015-01-01

The eruption of a filament in a kinklike fashion is often regarded as a signature of kink instability. However, the kink instability threshold for the filament’s magnetic structure is not widely understood. Using Hα observations from the New Vacuum Solar Telescope, we present a partial eruptive filament. During the eruption, the filament thread appeared to split from its middle and to break out in a kinklike fashion. In this period, the remaining filament material stayed below and erupted without the kinking motion later on. The coronal magnetic field lines associated with the filament are obtained from nonlinear force-free field extrapolations using the twelve-minute-cadence vector magnetograms of the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory. We studied the extrapolated field lines passing through the magnetic dips which are in good agreement with the observed filament. The field lines are non-uniformly twisted and appear to be composed of two twisted flux ropes winding around each other. One of them has a higher twist than the other, and the flux rope with the higher twist has its dips aligned with the kinking eruptive thread at the beginning of its eruption. Before the eruption, moreover, the flux rope with the higher twist was found to expand with an approximately constant field twist. In addition, the helicity flux maps deduced from the HMI magnetograms show that some helicity is injected into the overlying magnetic arcade, but no significant helicity is injected into the flux ropes. Accordingly, we suggest that the highly twisted flux rope became kink unstable when the instability threshold declined with the expansion of the flux rope

The heterocyst differentiation transcriptional regulator HetR of the filamentous cyanobacterium Anabaena forms tetramers and can be regulated by phosphorylation.

Science.gov (United States)

Valladares, Ana; Flores, Enrique; Herrero, Antonia

2016-02-01

Many filamentous cyanobacteria respond to the external cue of nitrogen scarcity by the differentiation of heterocysts, cells specialized in the fixation of atmospheric nitrogen in oxic environments. Heterocysts follow a spatial pattern along the filament of two heterocysts separated by ca. 10-15 vegetative cells performing oxygenic photosynthesis. HetR is a transcriptional regulator that directs heterocyst differentiation. In the model strain Anabaena sp. PCC 7120, the HetR protein was observed in various oligomeric forms in vivo, including a tetramer that peaked with maximal hetR expression during differentiation. Tetramers were not detected in a hetR point mutant incapable of differentiation, but were conspicuous in an over-differentiating strain lacking the PatS inhibitor. In differentiated filaments the HetR tetramer was restricted to heterocysts, being undetectable in vegetative cells. HetR co-purified with RNA polymerase from Anabaena mainly as a tetramer. In vitro, purified recombinant HetR was distributed between monomers, dimers, trimers and tetramers, and it was phosphorylated when incubated with (γ-(32)P)ATP. Phosphorylation and PatS hampered the accumulation of HetR tetramers and impaired HetR binding to DNA. In summary, tetrameric HetR appears to represent a functionally relevant form of HetR, whose abundance in the Anabaena filament could be negatively regulated by phosphorylation and by PatS. © 2015 John Wiley & Sons Ltd.

Extension of filament propagation in water with Bessel-Gaussian beams

Directory of Open Access Journals (Sweden)

G. Kaya

2016-03-01

Full Text Available We experimentally studied intense femtosecond pulse filamentation and propagation in water for Bessel-Gaussian beams with different numbers of radial modal lobes. The transverse modes of the incident Bessel-Gaussian beam were created from a Gaussian beam of a Ti:sapphire laser system by using computer generated hologram techniques. We found that filament propagation length increased with increasing number of lobes under the conditions of the same peak intensity, pulse duration, and the size of the central peak of the incident beam, suggesting that the radial modal lobes may serve as an energy reservoir for the filaments formed by the central intensity peak.

Dissipative light-bullets in the filamentation of femtosecond pulses

International Nuclear Information System (INIS)

Porras, M.A.; Gonzalo, I.

2010-01-01

Complete text of publication follows. With the growing interest in filamentation in solid and liquid media, the regime of filamentation with anomalous dispersion is receiving more attention. In this work we show that basics aspects of the filament dynamics in this regime can be explained in terms of a novel type of light-bullet, which is not of solitary or of conical types, but a wave-packet that maximizes the energy dissipation into the medium while remaining localized and stationary in propagation. We first show that a nonlinear optical medium at a given carrier wave length at which dispersion is anomalous, supports 'dissipative' light-bullets, i.e., waves localized in space and time and that propagate without change as a result of a balance between nonlinear compression and nonlinear absorption. Among them, the particular dissipative light-bullet with the highest possible dissipation is unique in a given medium, in the sense that all its properties are fixed by the properties of the medium at the carrier wave length. In this light-bullet, self-focusing continuously transports energy towards the pulse center by an amount that just compensates for the nonlinear losses. Figure 1(a) shows the radial profiles of the dissipative light-bullets that maximizes energy dissipation for several orders of multi-photon absorption responsible for the nonlinear losses. We have also found that this dissipative light-bullet tends to be spontaneously formed in the filamentary dynamics in media with anomalous dispersion. Figure 1(b) shows the peak intensity, the total energy and losses of a pulse that undergoes self-focusing and filamentation in an ideal medium with only Kerr nonlinearity and multi-photon absorption. This simple model reproduces the particularly long filament 'segments' and the 'burst' observed in experiments and in more accurate simulations. The peak intensity in the filament is identical to that of the dissipative light-bullet with maximum dissipation, and the

SOLAR MAGNETIZED 'TORNADOES': RELATION TO FILAMENTS

Energy Technology Data Exchange (ETDEWEB)

Su Yang; Veronig, Astrid; Temmer, Manuela [IGAM-Kanzelhoehe Observatory, Institute of Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Wang Tongjiang [Department of Physics, Catholic University of America, Washington, DC 20064 (United States); Gan Weiqun, E-mail: yang.su@uni-graz.at [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

2012-09-10

Solar magnetized 'tornadoes', a phenomenon discovered in the solar atmosphere, appear as tornado-like structures in the corona but are rooted in the photosphere. Like other solar phenomena, solar tornadoes are a feature of magnetized plasma and therefore differ distinctly from terrestrial tornadoes. Here we report the first analysis of solar 'tornadoes' (two papers which focused on different aspects of solar tornadoes were published in the Astrophysical Journal Letters and Nature, respectively, during the revision of this Letter). A detailed case study of two events indicates that they are rotating vertical magnetic structures probably driven by underlying vortex flows in the photosphere. They usually exist as a group and are related to filaments/prominences, another important solar phenomenon whose formation and eruption are still mysteries. Solar tornadoes may play a distinct role in the supply of mass and twists to filaments. These findings could lead to a new explanation of filament formation and eruption.

Characterization of gold nanoparticle binding to microtubule filaments

International Nuclear Information System (INIS)

Zhou, Jing C.; Wang Xianghuai; Xue Mei; Xu Zheng; Hamasaki, Toshikazu; Yang, Yang; Wang Kang; Dunn, Bruce

2010-01-01

Microtubule (MT) protein filaments were used as templates for fabricating Au nanowires as a bottom-up approach for fabricating building blocks for future integrated circuits. Photochemical reduction methods were employed to form Au nanoparticles which bind and uniformly cover the MT filaments. Synthesis of the MT-templated Au nanowires was characterized using UV/vis spectroscopy and transmission electron microscopy (TEM). In addition, binding between the MT filaments and Au nanoparticles was investigated using surface enhanced Raman spectroscopy (SERS) and X-ray photoelectron spectroscopy (XPS) to establish the nature of the binding sites. A variety of functional groups were identified by SERS to interact with the Au including imidazole, sulfur, aromatic rings, amine, and carboxylate. The imidazole ring in the histidine is the most prominent functional group for Au binding. The results from these studies provide better understanding of the binding between Au and the biotemplate and give insight concerning methods to improve Au coverage for MT-templated Au nanowires.

Cations Stiffen Actin Filaments by Adhering a Key Structural Element to Adjacent Subunits

Science.gov (United States)

2016-01-01

Ions regulate the assembly and mechanical properties of actin filaments. Recent work using structural bioinformatics and site-specific mutagenesis favors the existence of two discrete and specific divalent cation binding sites on actin filaments, positioned in the long axis between actin subunits. Cation binding at one site drives polymerization, while the other modulates filament stiffness and plays a role in filament severing by the regulatory protein, cofilin. Existing structural methods have not been able to resolve filament-associated cations, and so in this work we turn to molecular dynamics simulations to suggest a candidate binding pocket geometry for each site and to elucidate the mechanism by which occupancy of the “stiffness site” affects filament mechanical properties. Incorporating a magnesium ion in the “polymerization site” does not seem to require any large-scale change to an actin subunit’s conformation. Binding of a magnesium ion in the “stiffness site” adheres the actin DNase-binding loop (D-loop) to its long-axis neighbor, which increases the filament torsional stiffness and bending persistence length. Our analysis shows that bound D-loops occupy a smaller region of accessible conformational space. Cation occupancy buries key conserved residues of the D-loop, restricting accessibility to regulatory proteins and enzymes that target these amino acids. PMID:27146246

A Multi-spacecraft View of a Giant Filament Eruption during 2009 September 26/27

Science.gov (United States)

Gosain, Sanjay; Schmieder, Brigitte; Artzner, Guy; Bogachev, Sergei; Török, Tibor

2012-12-01

We analyze multi-spacecraft observations of a giant filament eruption that occurred during 2009 September 26 and 27. The filament eruption was associated with a relatively slow coronal mass ejection. The filament consisted of a large and a small part, and both parts erupted nearly simultaneously. Here we focus on the eruption associated with the larger part of the filament. The STEREO satellites were separated by about 117° during this event, so we additionally used SoHO/EIT and CORONAS/TESIS observations as a third eye (Earth view) to aid our measurements. We measure the plane-of-sky trajectory of the filament as seen from STEREO-A and TESIS viewpoints. Using a simple trigonometric relation, we then use these measurements to estimate the true direction of propagation of the filament which allows us to derive the true R/R ⊙-time profile of the filament apex. Furthermore, we develop a new tomographic method that can potentially provide a more robust three-dimensional (3D) reconstruction by exploiting multiple simultaneous views. We apply this method also to investigate the 3D evolution of the top part of filament. We expect this method to be useful when SDO and STEREO observations are combined. We then analyze the kinematics of the eruptive filament during its rapid acceleration phase by fitting different functional forms to the height-time data derived from the two methods. We find that for both methods an exponential function fits the rise profile of the filament slightly better than parabolic or cubic functions. Finally, we confront these results with the predictions of theoretical eruption models.

A MULTI-SPACECRAFT VIEW OF A GIANT FILAMENT ERUPTION DURING 2009 SEPTEMBER 26/27

Energy Technology Data Exchange (ETDEWEB)

Gosain, Sanjay [National Solar Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Schmieder, Brigitte [LESIA, Observatoire de Paris, CNRS, UPMC, Universite Paris Diderot, 5 Place Jules Janssen, F-92190 Meudon (France); Artzner, Guy [CNRS UMR 8617, Institut d' astrophysique Spatiale (IAS), F-91405 Orsay Cedex (France); Bogachev, Sergei [Lebedev Physical Institute of Russian Academy of Science, Leninskij prospekt 53, Moscow 119991 (Russian Federation); Toeroek, Tibor [Predictive Science, Inc., 9990 Mesa Rim Rd., Suite 170, San Diego, CA 92121 (United States)

2012-12-10

We analyze multi-spacecraft observations of a giant filament eruption that occurred during 2009 September 26 and 27. The filament eruption was associated with a relatively slow coronal mass ejection. The filament consisted of a large and a small part, and both parts erupted nearly simultaneously. Here we focus on the eruption associated with the larger part of the filament. The STEREO satellites were separated by about 117 Degree-Sign during this event, so we additionally used SoHO/EIT and CORONAS/TESIS observations as a third eye (Earth view) to aid our measurements. We measure the plane-of-sky trajectory of the filament as seen from STEREO-A and TESIS viewpoints. Using a simple trigonometric relation, we then use these measurements to estimate the true direction of propagation of the filament which allows us to derive the true R/R{sub Sun }-time profile of the filament apex. Furthermore, we develop a new tomographic method that can potentially provide a more robust three-dimensional (3D) reconstruction by exploiting multiple simultaneous views. We apply this method also to investigate the 3D evolution of the top part of filament. We expect this method to be useful when SDO and STEREO observations are combined. We then analyze the kinematics of the eruptive filament during its rapid acceleration phase by fitting different functional forms to the height-time data derived from the two methods. We find that for both methods an exponential function fits the rise profile of the filament slightly better than parabolic or cubic functions. Finally, we confront these results with the predictions of theoretical eruption models.

A MULTI-SPACECRAFT VIEW OF A GIANT FILAMENT ERUPTION DURING 2009 SEPTEMBER 26/27

International Nuclear Information System (INIS)

Gosain, Sanjay; Schmieder, Brigitte; Artzner, Guy; Bogachev, Sergei; Török, Tibor

2012-01-01

We analyze multi-spacecraft observations of a giant filament eruption that occurred during 2009 September 26 and 27. The filament eruption was associated with a relatively slow coronal mass ejection. The filament consisted of a large and a small part, and both parts erupted nearly simultaneously. Here we focus on the eruption associated with the larger part of the filament. The STEREO satellites were separated by about 117° during this event, so we additionally used SoHO/EIT and CORONAS/TESIS observations as a third eye (Earth view) to aid our measurements. We measure the plane-of-sky trajectory of the filament as seen from STEREO-A and TESIS viewpoints. Using a simple trigonometric relation, we then use these measurements to estimate the true direction of propagation of the filament which allows us to derive the true R/R ☉ -time profile of the filament apex. Furthermore, we develop a new tomographic method that can potentially provide a more robust three-dimensional (3D) reconstruction by exploiting multiple simultaneous views. We apply this method also to investigate the 3D evolution of the top part of filament. We expect this method to be useful when SDO and STEREO observations are combined. We then analyze the kinematics of the eruptive filament during its rapid acceleration phase by fitting different functional forms to the height-time data derived from the two methods. We find that for both methods an exponential function fits the rise profile of the filament slightly better than parabolic or cubic functions. Finally, we confront these results with the predictions of theoretical eruption models.

Fast, controlled stepping drive for D2 filament ejection

International Nuclear Information System (INIS)

Amenda, W.; Lang, R.S.

1985-01-01

Centrifugal pellet injectors are required to refuel plasma machines. The pellet feed into the centrifuge should, if possible, be direct to keep the exit angle divergence small. The D 2 filaments used are first stored in a cryostat and then rapidly transported to the intake region of the centrifuge. An intermittent drive for fast, controlled ejection of D 2 filaments is described here. Mean filament speed of up to 0.6 m/s per step (1.2 mm) are achieved for the centrifugal pellet injector which refuels the ASDEX tokamak at Garching. The timing of the (81) step shifts can be synchronized with the rotor motion. The drive allows rates of up to 50 pellets per second. The drive method also seems to be suitable for direct feeding of other known centrifugal pellet injectors

Density profiles in the Scrape-Off Layer interpreted through filament dynamics

Science.gov (United States)

Militello, Fulvio

2017-10-01

We developed a new theoretical framework to clarify the relation between radial Scrape-Off Layer density profiles and the fluctuations that generate them. The framework provides an interpretation of the experimental features of the profiles and of the turbulence statistics on the basis of simple properties of the filaments, such as their radial motion and their draining towards the divertor. L-mode and inter-ELM filaments are described as a Poisson process in which each event is independent and modelled with a wave function of amplitude and width statistically distributed according to experimental observations and evolving according to fluid equations. We will rigorously show that radially accelerating filaments, less efficient parallel exhaust and also a statistical distribution of their radial velocity can contribute to induce flatter profiles in the far SOL and therefore enhance plasma-wall interactions. A quite general result of our analysis is the resiliency of this non-exponential nature of the profiles and the increase of the relative fluctuation amplitude towards the wall, as experimentally observed. According to the framework, profile broadening at high fueling rates can be caused by interactions with neutrals (e.g. charge exchange) in the divertor or by a significant radial acceleration of the filaments. The framework assumptions were tested with 3D numerical simulations of seeded SOL filaments based on a two fluid model. In particular, filaments interact through the electrostatic field they generate only when they are in close proximity (separation comparable to their width in the drift plane), thus justifying our independence hypothesis. In addition, we will discuss how isolated filament motion responds to variations in the plasma conditions, and specifically divertor conditions. Finally, using the theoretical framework we will reproduce and interpret experimental results obtained on JET, MAST and HL-2A.

Characterization of type-I ELM induced filaments in the far scrape-off layer of ASDEX upgrade

Energy Technology Data Exchange (ETDEWEB)

Schmid, Andreas

2008-03-18

This thesis focuses on the characterization of filaments and their propagation in the ASDEX Upgrade tokamak. The aim is to provide experimental measurements for understanding the filament formation process and their temporal evolution, and to provide a comprehensive database for an extrapolation to future fusion devices. For this purpose, a new magnetically driven probe for filament measurements has been developed and installed in ASDEX Upgrade. The probe carries several Langmuir probes and a magnetic coil in between. The Langmuir probes allow for measurements of the radial and poloidal/toroidal propagation of filaments as well as for measurements of filament size, density, and their radial (or temporal) evolution. The magnetic coil on the filament probe allows for measurements of currents in the filaments. A set of 7 coils, measuring 3 field components at different positions along the filament, has been used to measure the magnetic signature during an ELM. The aim was, on the one hand, to study which role filaments play for the magnetic structure, and on the other hand if the parallel currents predicted by the sheath damped model could be verified. Filament temperatures have been derived and the corresponding heat transport mechanisms have been studied. (orig.)

Characterization of type-I ELM induced filaments in the far scrape-off layer of ASDEX upgrade

International Nuclear Information System (INIS)

Schmid, Andreas

2008-01-01

This thesis focuses on the characterization of filaments and their propagation in the ASDEX Upgrade tokamak. The aim is to provide experimental measurements for understanding the filament formation process and their temporal evolution, and to provide a comprehensive database for an extrapolation to future fusion devices. For this purpose, a new magnetically driven probe for filament measurements has been developed and installed in ASDEX Upgrade. The probe carries several Langmuir probes and a magnetic coil in between. The Langmuir probes allow for measurements of the radial and poloidal/toroidal propagation of filaments as well as for measurements of filament size, density, and their radial (or temporal) evolution. The magnetic coil on the filament probe allows for measurements of currents in the filaments. A set of 7 coils, measuring 3 field components at different positions along the filament, has been used to measure the magnetic signature during an ELM. The aim was, on the one hand, to study which role filaments play for the magnetic structure, and on the other hand if the parallel currents predicted by the sheath damped model could be verified. Filament temperatures have been derived and the corresponding heat transport mechanisms have been studied. (orig.)

Effect of an Energy Reservoir on the Atmospheric Propagation of Laser-Plasma Filaments

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Eisenmann, Shmuel; Peñano, Joseph; Sprangle, Phillip; Zigler, Arie

2008-04-01

The ability to select and stabilize a single filament during propagation of an ultrashort, high-intensity laser pulse in air makes it possible to examine the longitudinal structure of the plasma channel left in its wake. We present the first detailed measurements and numerical 3-D simulations of the longitudinal plasma density variation in a laser-plasma filament after it passes through an iris that blocks the surrounding energy reservoir. Since no compensation is available from the surrounding background energy, filament propagation is terminated after a few centimeters. For this experiment, simulations indicate that filament propagation is terminated by plasma defocusing and ionization loss, which reduces the pulse power below the effective self-focusing power. With no blockage, a plasma filament length of over a few meters was observed.

Effect of an Energy Reservoir on the Atmospheric Propagation of Laser-Plasma Filaments

International Nuclear Information System (INIS)

Eisenmann, Shmuel; Penano, Joseph; Sprangle, Phillip; Zigler, Arie

2008-01-01

The ability to select and stabilize a single filament during propagation of an ultrashort, high-intensity laser pulse in air makes it possible to examine the longitudinal structure of the plasma channel left in its wake. We present the first detailed measurements and numerical 3-D simulations of the longitudinal plasma density variation in a laser-plasma filament after it passes through an iris that blocks the surrounding energy reservoir. Since no compensation is available from the surrounding background energy, filament propagation is terminated after a few centimeters. For this experiment, simulations indicate that filament propagation is terminated by plasma defocusing and ionization loss, which reduces the pulse power below the effective self-focusing power. With no blockage, a plasma filament length of over a few meters was observed

The giant protein titin regulates the length of the striated muscle thick filament.

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Tonino, Paola; Kiss, Balazs; Strom, Josh; Methawasin, Mei; Smith, John E; Kolb, Justin; Labeit, Siegfried; Granzier, Henk

2017-10-19

The contractile machinery of heart and skeletal muscles has as an essential component the thick filament, comprised of the molecular motor myosin. The thick filament is of a precisely controlled length, defining thereby the force level that muscles generate and how this force varies with muscle length. It has been speculated that the mechanism by which thick filament length is controlled involves the giant protein titin, but no conclusive support for this hypothesis exists. Here we show that in a mouse model in which we deleted two of titin's C-zone super-repeats, thick filament length is reduced in cardiac and skeletal muscles. In addition, functional studies reveal reduced force generation and a dilated cardiomyopathy (DCM) phenotype. Thus, regulation of thick filament length depends on titin and is critical for maintaining muscle health.

Thin filament length in the cardiac sarcomere varies with sarcomere length but is independent of titin and nebulin.

Science.gov (United States)

Kolb, Justin; Li, Frank; Methawasin, Mei; Adler, Maya; Escobar, Yael-Natalie; Nedrud, Joshua; Pappas, Christopher T; Harris, Samantha P; Granzier, Henk

2016-08-01

Thin filament length (TFL) is an important determinant of the force-sarcomere length (SL) relation of cardiac muscle. However, the various mechanisms that control TFL are not well understood. Here we tested the previously proposed hypothesis that the actin-binding protein nebulin contributes to TFL regulation in the heart by using a cardiac-specific nebulin cKO mouse model (αMHC Cre Neb cKO). Atrial myocytes were studied because nebulin expression has been reported to be most prominent in this cell type. TFL was measured in right and left atrial myocytes using deconvolution optical microscopy and staining for filamentous actin with phalloidin and for the thin filament pointed-end with an antibody to the capping protein Tropomodulin-1 (Tmod1). Results showed that TFLs in Neb cKO and littermate control mice were not different. Thus, deletion of nebulin in the heart does not alter TFL. However, TFL was found to be ~0.05μm longer in the right than in the left atrium and Tmod1 expression was increased in the right atrium. We also tested the hypothesis that the length of titin's spring region is a factor controlling TFL by studying the Rbm20(ΔRRM) mouse which expresses titins that are ~500kDa (heterozygous mice) and ~1000kDa (homozygous mice) longer than in control mice. Results revealed that TFL was not different in Rbm20(ΔRRM) mice. An unexpected finding in all genotypes studied was that TFL increased as sarcomeres were stretched (~0.1μm per 0.35μm of SL increase). This apparent increase in TFL reached a maximum at a SL of ~3.0μm where TFL was ~1.05μm. The SL dependence of TFL was independent of chemical fixation or the presence of cardiac myosin-binding protein C (cMyBP-C). In summary, we found that in cardiac myocytes TFL varies with SL in a manner that is independent of the size of titin or the presence of nebulin. Copyright © 2016. Published by Elsevier Ltd.

Stimulated Raman scattering in the presence of filamentation in underdense plasmas

International Nuclear Information System (INIS)

Barr, H.C.; Boyd, T.J.M.; Coutts, G.A.

1986-01-01

A model of stimulated Raman scattering from underdense plasmas in which the laser intensity profile and plasma density have been corrupted by the filamentation instability is described. The model accounts in a unified way for inhomogeneity in the density, for Landau damping, and for local enhancements in lightwave intensities. In shallow filaments the concentration of the light gives rise to modest increases in growth. On the other hand, for deeper filaments the inhomogeneity and Landau damping dominate to suppress the instability. In addition, backscatter is enhanced relative to sidescatter

Laser-filamentation-induced condensation and snow formation in a cloud chamber.

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Ju, Jingjing; Liu, Jiansheng; Wang, Cheng; Sun, Haiyi; Wang, Wentao; Ge, Xiaochun; Li, Chuang; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

2012-04-01

Using 1 kHz, 9 mJ femtosecond laser pulses, we demonstrate laser-filamentation-induced spectacular snow formation in a cloud chamber. An intense updraft of warm moist air is generated owing to the continuous heating by the high-repetition filamentation. As it encounters the cold air above, water condensation and large-sized particles spread unevenly across the whole cloud chamber via convection and cyclone like action on a macroscopic scale. This indicates that high-repetition filamentation plays a significant role in macroscopic laser-induced water condensation and snow formation.

Measurements of the Motion of Plasma Filaments in a Plasma Ball

International Nuclear Information System (INIS)

Campanell, M.; Laird, J.; Provost, T.; Vasquez, S.; Zweben, S.J.

2010-01-01

Measurements were made of the motion of the filamentary structures in a plasma ball using high speed cameras and other optical detectors. These filaments traverse the ball radially at ∼106 cm/sec at the driving frequency of ∼26 kHz, and drift upward through the ball at ∼1 cm/sec. Varying the applied high voltage and frequency caused the number, length, and diameter of the filaments to change. A custom plasma ball was constructed to observe the effects of varying gas pressure and species on the filament structures.

A rapid PCR-based approach for molecular identification of filamentous fungi.

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Chen, Yuanyuan; Prior, Bernard A; Shi, Guiyang; Wang, Zhengxiang

2011-08-01

In this study, a novel rapid and efficient DNA extraction method based on alkaline lysis, which can deal with a large number of filamentous fungal isolates in the same batch, was established. The filamentous fungal genomic DNA required only 20 min to prepare and can be directly used as a template for PCR amplification. The amplified internal transcribed spacer regions were easy to identify by analysis. The extracted DNA also can be used to amplify other protein-coding genes for fungal identification. This method can be used for rapid systematic identification of filamentous fungal isolates.

Measurements of the Motion of Plasma Filaments in a Plasma Ball

Energy Technology Data Exchange (ETDEWEB)

Campanell, M.; Laird, J.; Provost, T.; Vasquez, S.; Zweben, S. J.

2010-01-26

Measurements were made of the motion of the filamentary structures in a plasma ball using high speed cameras and other optical detectors. These filaments traverse the ball radially at ~106 cm/sec at the driving frequency of ~26 kHz, and drift upward through the ball at ~1 cm/sec. Varying the applied high voltage and frequency caused the number, length, and diameter of the filaments to change. A custom plasma ball was constructed to observe the effects of varying gas pressure and species on the filament structures.

Small-scale eruptive filaments on the quiet sun

International Nuclear Information System (INIS)

Hermans, L.M.; Martin, S.F.

1986-01-01

A study of a little known class of eruptive events on the quiet sun was conducted. All of 61 small-scale eruptive filamentary structures were identified in a systematic survey of 32 days of H alpha time-lapse films of the quiet sun acquired at Big Bear Solar Observatory. When fully developed, these structures have an average length of 15 arc seconds before eruption. They appear to be the small-scale analog of large-scale eruptive filaments observed against the disk. At the observed rate of 1.9 small-scale eruptive features per field of view per average 7.0 hour day, the rate of occurence of these events on the sun were estimated to be greater than 600 per 24 hour day.. The average duration of the eruptive phase was 26 minutes while the average lifetime from formation through eruption was 70 minutes. A majority of the small-scale filamentary sturctures were spatially related to cancelling magnetic features in line-of-sight photospheric magnetograms. Similar to large-scale filaments, the small-scale filamentary structures sometimes divided opposite polarity cancelling fragments but often had one or both ends terminating at a cancellation site. Their high numbers appear to reflect the much greater flux on the quiet sun. From their characteristics, evolution, and relationship to photospheric magnetic flux, it was concluded that the structures described are small-scale eruptive filaments and are a subset of all filaments

Wettability dynamics of liquid filaments on horizontal substrates

Science.gov (United States)

Diez, Javier; Ravazzoli, Pablo; Cuellar, Ingrith; Gonzalez, Alejandro

2017-11-01

We study the hydrodynamic mechanisms involved in the motion of the contact line formed at the end region of a liquid filament laying on a planar and horizontal substrate. Since the flow develops under partially wetting conditions, the tip of the filament recedes and forms a bulged region (head) that subsequently develops a neck region behind it. Later the neck breaks up leading to a separated drop, while the rest of the filament restarts the sequence. One main feature of this flow is that the whole dynamics and final drop shapes are strongly influenced by the hysteresis of the contact angle typical in most of the liquid-substrate systems. The time evolution till breakup is studied experimentally and pictured in terms of a hybrid wettability theory which involves the Cox-Voinov hydrodynamic approach combined with the molecular kinetic theory developed by Blake. The parameters of this theory are determined for our liquid-substrate system (silicone oil ``coated glass). The experimental results of the retracting filament are described in terms of a simple heuristic model and compared with numerical simulations of the full Navier-Stokes equations. This study is of special interest in the context of pulsed laser-induced dewetting. The authors acknowledge support from Consejo Nacional de Investigaciones Cientficas y Tcnicas (CONICET, Argentina) with Grant PIP 844/2012 and Agencia Nacional de Promocin Cientfica y Tecnolgica (ANPCyT, Argentina) with Grant PICT 931/2012.

Bundling Actin Filaments From Membranes: Some Novel Players

Directory of Open Access Journals (Sweden)

Clément eThomas

2012-08-01

Full Text Available Progress in live-cell imaging of the cytoskeleton has significantly extended our knowledge about the organization and dynamics of actin filaments near the plasma membrane of plant cells. Noticeably, two populations of filamentous structures can be distinguished. On the one hand, fine actin filaments which exhibit an extremely dynamic behavior basically characterized by fast polymerization and prolific severing events, a process referred to as actin stochastic dynamics. On the other hand, thick actin bundles which are composed of several filaments and which are comparatively more stable although they constantly remodel as well. There is evidence that the actin cytoskeleton plays critical roles in trafficking and signaling at both the cell cortex and organelle periphery but the exact contribution of actin bundles remains unclear. A common view is that actin bundles provide the long-distance tracks used by myosin motors to deliver their cargo to growing regions and accordingly play a particularly important role in cell polarization. However, several studies support that actin bundles are more than simple passive highways and display multiple and dynamic roles in the regulation of many processes, such as cell elongation, polar auxin transport, stomatal and chloroplast movement, and defense against pathogens. The list of identified plant actin-bundling proteins is ever expanding, supporting that plant cells shape structurally and functionally different actin bundles. Here I review the most recently characterized actin-bundling proteins, with a particular focus on those potentially relevant to membrane trafficking and/or signaling.

EIT and SXT Observations of a Quiet Region Filament Ejection: First Eruption, Then Reconnection

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Sterling, Alphonse C.; Moore, Ronald L.; Thompson, Barbara J.; Six, N. Frank (Technical Monitor)

2001-01-01

We observe a slow-onset quiet-region filament eruption with the EUV Imaging Telescope (EIT) on SOHO, and the Soft X-ray Telescope (SXT) on Yohkoh. This event occurred on 1999 April 18, and was likely the origin of a coronal mass ejection (CME) detected by SOHO at 08:30 UT on that day. In EIT, one-half of the filament shows two stages of evolution: Stage I is a slow, roughly constant upward movement at approx. 1 km per second lasting approximately 6.5 hours, and Stage 2 is a rapid upward eruption at approximately 16 kilometers per second occurring just before the filament disappears into interplanetary space. The other half of the filament shows little motion along the line-of-sight during the time of Stage 1, but erupts along with the rest of the filament during Stage 2. There is no obvious emission from the filament in SXT until Stage 2; at that time an arcade of EUV and soft X-ray loops forms first at the central location of the filament, and then expands outward along the length of the filament channel. A plot of EUV intensity versus time of the central portion of the filament (where the postflare loops initially form) shows a flat profile during Stage 1, and a rapid upturn after the start of Stage 2. This lightcurve is delayed from what would be expected if "tether-cutting" reconnection in the core of the erupting region were responsible for the initiation of the eruption. Rather, these observations suggest that a loss of stability of the magnetic field holding the filament initiates the eruption, with reconnection in the core region occurring only as a byproduct.

EIT And SXT Observations of a Quiet-Region Filament Ejection: First Eruption, Then Reconnection

Science.gov (United States)

Sterling, Alphonse C.; Moore, Ronald L.; Thompson, Barbara J.

2001-01-01

We observe a slow-onset quiet-region filament eruption with the Extreme Ultraviolet Imaging Telescope (EIT) on the Solar Heliospheric Observatory (SOHO) and the Soft X-ray Telescope (SXT) on Yohkoh. This event occurred on 1999 April 18 and was likely the origin of a coronal mass ejection detected by SOHO at 08:30 UT on that day. In the EIT observation, one-half of the filament shows two stages of evolution: stage 1 is a slow, roughly constant upward movement at approximately 1 km/s lasting approximately 0.5 hr, and stage 2 is a rapid upward eruption at approximately 16 km/s occurring just before the filament disappears into interplanetary space. The other half of the filament shows little motion along the line of sight during the time of stage 1 but erupts along with the rest of the filament during stage 2. There is no obvious emission from the filament in the SXT observation until stage 2; at that time, an arcade of EUV and soft X-ray loops forms first at the central location of the filament and then expands outward along the length of the filament channel. A plot of EUV intensity versus time of the central portion of the filament (where the postflare loops initially form) shows a flat profile during stage 1 and a rapid upturn after the start of stage 2. This light curve is delayed from what would be expected if 'tether-cutting' reconnection in the core of the erupting region were responsible for the initiation of the eruption. Rather, these observations suggest that a loss of stability of the magnetic field holding the filament initiates the eruption, with reconnection in the core region occurring only as a by-product.

Differential requirements of two recA mutants for constitutive SOS expression in Escherichia coli K-12.

Directory of Open Access Journals (Sweden)

Jarukit Edward Long

Full Text Available Repairing DNA damage begins with its detection and is often followed by elicitation of a cellular response. In E. coli, RecA polymerizes on ssDNA produced after DNA damage and induces the SOS Response. The RecA-DNA filament is an allosteric effector of LexA auto-proteolysis. LexA is the repressor of the SOS Response. Not all RecA-DNA filaments, however, lead to an SOS Response. Certain recA mutants express the SOS Response (recA(C in the absence of external DNA damage in log phase cells.Genetic analysis of two recA(C mutants was used to determine the mechanism of constitutive SOS (SOS(C expression in a population of log phase cells using fluorescence of single cells carrying an SOS reporter system (sulAp-gfp. SOS(C expression in recA4142 mutants was dependent on its initial level of transcription, recBCD, recFOR, recX, dinI, xthA and the type of medium in which the cells were grown. SOS(C expression in recA730 mutants was affected by none of the mutations or conditions tested above.It is concluded that not all recA(C alleles cause SOS(C expression by the same mechanism. It is hypothesized that RecA4142 is loaded on to a double-strand end of DNA and that the RecA filament is stabilized by the presence of DinI and destabilized by RecX. RecFOR regulate the activity of RecX to destabilize the RecA filament. RecA730 causes SOS(C expression by binding to ssDNA in a mechanism yet to be determined.

Filament-induced remote surface ablation for long range laser-induced breakdown spectroscopy operation

International Nuclear Information System (INIS)

Rohwetter, Ph.; Stelmaszczyk, K.; Woeste, L.; Ackermann, R.; Mejean, G.; Salmon, E.; Kasparian, J.; Yu, J.; Wolf, J.-P.

2005-01-01

We demonstrate laser induced ablation and plasma line emission from a metallic target at distances up to 180 m from the laser, using filaments (self-guided propagation structures ∼ 100 μm in diameter and ∼ 5 x 10 13 W/cm 2 in intensity) appearing as femtosecond and terawatt laser pulses propagating in air. The remarkable property of filaments to propagate over a long distance independently of the diffraction limit opens the frontier to long range operation of the laser-induced breakdown spectroscopy technique. We call this special configuration of remote laser-induced breakdown spectroscopy 'remote filament-induced breakdown spectroscopy'. Our results show main features of filament-induced ablation on the surface of a metallic sample and associated plasma emission. Our experimental data allow us to estimate requirements for the detection system needed for kilometer-range remote filament-induced breakdown spectroscopy experiment

Femtosecond filaments for rapid and flexible writing of Fiber-Bragg grating (Conference Presentation)

Science.gov (United States)

Ertorer, Erden; Haque, Moez; Li, Jianzhao; Herman, Peter R.

2017-03-01

Kerr-lens self-channelling of femtosecond laser light offers a novel high-aspect geometry for laser processing inside transparent materials. In glass materials, the laser filaments enable white-light continuum generation, scribing, nanochannel formation, and refractive index modification. In the present work, refractive index matching oils were applied around optical fiber to eliminate astigmatic aberration and thereby form highly symmetric and uniform filaments selectively in the cladding or core waveguide of standard single-mode optical fibre (SMF-28). Under tight focusing, long filaments exceeding 20 um length were formed with single pulses to sub-micron diameter. Arrays of 0.5 um spaced filaments are verified by formation of strong fiber Bragg gratings (FBGs). Flexible positioning of the filament arrays within the fiber core offers wide scope for coupling to cladding and radiation modes and creating new types of in-fibre optical devices.

Stochastic calculus of protein filament formation under spatial confinement

Science.gov (United States)

Michaels, Thomas C. T.; Dear, Alexander J.; Knowles, Tuomas P. J.

2018-05-01

The growth of filamentous aggregates from precursor proteins is a process of central importance to both normal and aberrant biology, for instance as the driver of devastating human disorders such as Alzheimer's and Parkinson's diseases. The conventional theoretical framework for describing this class of phenomena in bulk is based upon the mean-field limit of the law of mass action, which implicitly assumes deterministic dynamics. However, protein filament formation processes under spatial confinement, such as in microdroplets or in the cellular environment, show intrinsic variability due to the molecular noise associated with small-volume effects. To account for this effect, in this paper we introduce a stochastic differential equation approach for investigating protein filament formation processes under spatial confinement. Using this framework, we study the statistical properties of stochastic aggregation curves, as well as the distribution of reaction lag-times. Moreover, we establish the gradual breakdown of the correlation between lag-time and normalized growth rate under spatial confinement. Our results establish the key role of spatial confinement in determining the onset of stochasticity in protein filament formation and offer a formalism for studying protein aggregation kinetics in small volumes in terms of the kinetic parameters describing the aggregation dynamics in bulk.

AC Loss Reduction in Filamentized YBCO Coated Conductors with Virtual Transverse Cross-cuts

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yifei [ORNL; Duckworth, Robert C [ORNL; Ha, Tam T [ORNL; List III, Frederick Alyious [ORNL; Gouge, Michael J [ORNL; Chen, Y [SuperPower Incorporated, Schenectady, New York; X, Xiong, [SuperPower Incorporated, Schenectady, New York; Selvamanickam, V. [SuperPower Incorporated, Schenectady, New York

2011-01-01

While the performance of YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO)-based coated conductors under dc currents has improved significantly in recent years, filamentization is being investigated as a technique to reduce ac loss so that the 2nd generation (2G) high temperature superconducting (HTS) wires can also be utilized in various ac power applications such as cables, transformers and fault current limiters. Experimental studies have shown that simply filamentizing the superconducting layer is not effective enough to reduce ac loss because of incomplete flux penetration in between the filaments as the length of the tape increases. To introduce flux penetration in between the filaments more uniformly and further reduce the ac loss, virtual transverse cross-cuts were made in superconducting filaments of the coated conductors fabricated using the metal organic chemical vapor deposition (MOCVD) method. The virtual transverse cross-cuts were formed by making cross-cuts (17 - 120 {micro}m wide) on the IBAD (ion beam assisted deposition)-MgO templates using laser scribing followed by depositing the superconducting layer ({approx} 0.6 {micro}m thick). AC losses were measured and compared for filamentized conductors with and without the cross-cuts under applied peak ac fields up to 100 mT. The results were analyzed to evaluate the efficacy of filament decoupling and the feasibility of using this method to achieve ac loss reduction.

Vortex Filaments in Grids for Scalable, Fine Smoke Simulation.

Science.gov (United States)

Meng, Zhang; Weixin, Si; Yinling, Qian; Hanqiu, Sun; Jing, Qin; Heng, Pheng-Ann

2015-01-01

Vortex modeling can produce attractive visual effects of dynamic fluids, which are widely applicable for dynamic media, computer games, special effects, and virtual reality systems. However, it is challenging to effectively simulate intensive and fine detailed fluids such as smoke with fast increasing vortex filaments and smoke particles. The authors propose a novel vortex filaments in grids scheme in which the uniform grids dynamically bridge the vortex filaments and smoke particles for scalable, fine smoke simulation with macroscopic vortex structures. Using the vortex model, their approach supports the trade-off between simulation speed and scale of details. After computing the whole velocity, external control can be easily exerted on the embedded grid to guide the vortex-based smoke motion. The experimental results demonstrate the efficiency of using the proposed scheme for a visually plausible smoke simulation with macroscopic vortex structures.

The intermediate filament protein vimentin binds specifically to a recombinant integrin α2/β1 cytoplasmic tail complex and co-localizes with native α2/β1 in endothelial cell focal adhesions

International Nuclear Information System (INIS)

Kreis, Stephanie; Schoenfeld, Hans-Joachim; Melchior, Chantal; Steiner, Beat; Kieffer, Nelly

2005-01-01

Integrin receptors are crucial players in cell adhesion and migration. Identification and characterization of cellular proteins that interact with their short α and β cytoplasmic tails will help to elucidate the molecular mechanisms by which integrins mediate bi-directional signaling across the plasma membrane. Integrin α2β1 is a major collagen receptor but to date, only few proteins have been shown to interact with the α2 cytoplasmic tail or with the α2β1 complex. In order to identify novel binding partners of a α2β1cytoplasmic domain complex, we have generated recombinant GST-fusion proteins, incorporating the leucine zipper heterodimerization cassettes of Jun and Fos. To ascertain proper functionality of the recombinant proteins, interaction with natural binding partners was tested. GST-α2 and GST-Jun α2 bound His-tagged calreticulin while GST-β1 and GST-Fos β1 proteins bound talin. In screening assays for novel binding partners, the immobilized GST-Jun α2/GST-Fos β1 heterodimeric complex, but not the single subunits, interacted specifically with endothelial cell-derived vimentin. Vimentin, an abundant intermediate filament protein, has previously been shown to co-localize with αvβ3-positive focal contacts. Here, we provide evidence that this interaction also occurs with α2β1-enriched focal adhesions and we further show that this association is lost after prolonged adhesion of endothelial cells to collagen

Limitation of critical current density by intermetallic formation in fine filament Nb-Ti superconductors

International Nuclear Information System (INIS)

Larbalestier, D.C.; Chengren, L.; Starch, W.; Lee, P.J.

1985-01-01

Two experiments have been performed to investigate the role that the intermetallic reaction between the copper matrix and the Nb-Ti filaments plays in limiting the critical current density (J/sub c/) of Nb 45.6 wt% Ti composites. The first experiment involved composites which were industrially extruded. It was found that as the number of heat treatments increased, the J/sub c/ declined, the resistive transition broadened and the filaments sausaged. The filament sausaging was initiated by intermetallic particles at the filament matrix interface. A series of many heat treatment procedures were then applied to composites fabricated in the authors own laboratories without extrusion. Very high J/sub c/ values were obtained at filament sizes of 20 μm. When the same heat treatment procedures were applied to 4 - 5 μm conductors, extensive sausaging and degraded J/sub c/ values resulted. This degradation was also found to be due to the formation of Cu-Nb-Ti intermetallic compounds. It is concluded that a reliable filament diffusion barrier technology is necessary to permit full flexibility in the heat treatment of 2 - 5 μ filament Nb-Ti composites

Limitation of critical current density by intermetallic formation in fine filament Nb-Ti superconductors

International Nuclear Information System (INIS)

Larbalestier, D.C.; Chengren, Li; Lee, P.J.; Starch, W.

1985-01-01

Two experiments have been performed to investigate the role that the intermetallic reaction between the copper matrix and the Nb-Ti filaments plays in limiting the critical current density (J /SUB c/ ) of Nb 46.5 wt% Ti composites. The first experiment involved composites which were industrially extruded. It was found that as the number of heat treatments increased, the J /SUB c/ declined, the resistive transition broadened and the filaments sausaged. The filament sausaging was initiated by intermetallic particles at the filament matrix interface. A series of many heat treatment procedures were then applied to composites fabricated in our own laboratories without extrusion. Very high J /SUB c/ values were obtained at filament sizes of 20 μm. When the same heat treatment procedures were applied to 4 - 5 μm conductors, extensive sausaging and degraded J /SUB c/ values resulted. This degradation was also found to be due to the formation of Cu-Nb-Ti intermetallic compounds. It is concluded that a reliable filament diffusion barrier technology is necessary to permit full flexibility in the heat treatment of 2 - 5 μm filament Nb-Ti composites

Motion of variable-length MreB filaments at the bacterial cell membrane influences cell morphology.

Science.gov (United States)

Reimold, Christian; Defeu Soufo, Herve Joel; Dempwolff, Felix; Graumann, Peter L

2013-08-01

The maintenance of rod-cell shape in many bacteria depends on actin-like MreB proteins and several membrane proteins that interact with MreB. Using superresolution microscopy, we show that at 50-nm resolution, Bacillus subtilis MreB forms filamentous structures of length up to 3.4 μm underneath the cell membrane, which run at angles diverging up to 40° relative to the cell circumference. MreB from Escherichia coli forms at least 1.4-μm-long filaments. MreB filaments move along various tracks with a maximal speed of 85 nm/s, and the loss of ATPase activity leads to the formation of extended and static filaments. Suboptimal growth conditions lead to formation of patch-like structures rather than extended filaments. Coexpression of wild-type MreB with MreB mutated in the subunit interface leads to formation of shorter MreB filaments and a strong effect on cell shape, revealing a link between filament length and cell morphology. Thus MreB has an extended-filament architecture with the potential to position membrane proteins over long distances, whose localization in turn may affect the shape of the cell wall.

Recycled Sm-Co bonded magnet filaments for 3D printing of magnets

Science.gov (United States)

Khazdozian, Helena A.; Manzano, J. Sebastián; Gandha, Kinjal; Slowing, Igor I.; Nlebedim, Ikenna C.

2018-05-01

Recycling of rare earth elements, such as Sm and Nd, is one technique towards mitigating long-term supply and cost concerns for materials and devices that depend on these elements. In this work recycled Sm-Co powder recovered from industrial grinding swarfs, or waste material from magnet processing, was investigated for use in preparation of filament for 3D printing of bonded magnets. Recycled Sm-Co powder recovered from swarfs was blended into polylactic acid (PLA). Up to 20 vol.% of the recycled Sm-Co in PLA was extruded at 160°C to produce a filament. It was demonstrated that no degradation of magnetic properties occurred due to the preparation or extrusion of the bonded magnet material. Good uniformity of the magnetic properties is exhibited throughout the filament, with the material first extruded being the exception. The material does exhibit some magnetic anisotropy, allowing for the possibility of the development of anisotropic filaments. This work provides a path forward for producing recycled magnetic filament for 3D printing of permanent magnets.