Journal articles on the topic 'Plasmodi'
To see the other types of publications on this topic, follow the link: Plasmodi.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Plasmodi.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Solnica-Krezel, L., T. G. Burland, and W. F. Dove. "Variable pathways for developmental changes of mitosis and cytokinesis in Physarum polycephalum." Journal of Cell Biology 113, no. 3 (May 1, 1991): 591–604. http://dx.doi.org/10.1083/jcb.113.3.591.
Full textAbstract:
The development of a uninucleate ameba into a multinucleate, syncytial plasmodium in myxomycetes involves a change from the open, astral mitosis of the ameba to the intranuclear, anastral mitosis of the plasmodium, and the omission of cytokinesis from the cell cycle. We describe immunofluorescence microscopic studies of the amebal-plasmodial transition (APT) in Physarum polycephalum. We demonstrate that the reorganization of mitotic spindles commences in uninucleate cells after commitment to plasmodium formation, is completed by the binucleate stage, and occurs via different routes in individual developing cells. Most uninucleate developing cells formed mitotic spindles characteristic either of amebae or of plasmodia. However, chimeric mitotic figures exhibiting features of both amebal and plasmodial mitoses, and a novel star microtubular array were also observed. The loss of the ameba-specific alpha 3-tubulin and the accumulation of the plasmodium-specific beta 2-tubulin isotypes during development were not sufficient to explain the changes in the organization of mitotic spindles. The majority of uninucleate developing cells undergoing astral mitoses (amebal and chimeric) exhibited cytokinetic furrows, whereas cells with the anastral plasmodial mitosis exhibited no furrows. Thus, the transition from astral to anastral mitosis during the APT could be sufficient for the omission of cytokinesis from the cell cycle. However, astral mitosis may not ensure cytokinesis: some cells undergoing amebal or chimeric mitosis contained unilateral cytokinetic furrows or no furrow at all. These cells would, most probably, fail to divide. We suggest that a uninucleate committed cell undergoing amebal or chimeric mitosis can either divide or else form a binucleate cell. In contrast, a uninucleate cell with a mitotic spindle of the plasmodial type gives rise only to a binucleate cells. Further, the decision to enter mitosis after commitment to the APT is independent of the developmental changes in the organization of the mitotic spindle and cytokinesis.
2
Salles-Passador, I., A. Moisand, V. Planques, and M. Wright. "Physarum plasmodia do contain cytoplasmic microtubules!" Journal of Cell Science 100, no. 3 (November 1, 1991): 509–20. http://dx.doi.org/10.1242/jcs.100.3.509.
Full textAbstract:
It has been claimed that the plasmodium of the myxomycete Physarum polycephalum constitutes a very unusual syncytium, devoid of cytoplasmic microtubules. In contrast, we have observed a cytoplasmic microtubule network, by both electron microscopy and immunofluorescence in standard synchronous plasmodia, either in semi-thin sections or in smears, and in thin plasmodia, used as a convenient model. Cytoplasmic microtubules could be seen after immunofluorescent staining with three different monospecific monoclonal anti-tubulin antibodies. The immunolabelling was strictly restricted to typical microtubules as shown by electron microscopy. These cytoplasmic microtubules were entirely and reversibly disassembled by cold treatment and by either of two microtubule poisons: methyl benzimidazole carbamate and griseofulvin. The microtubule network, present in all strains that have been studied, contains single microtubules and microtubule bundles composed of two to eight microtubules. Cytoplasmic microtubules form a dense and complex three-dimensional network, distinct from the microfilamentous domains and from the nuclei. The orientation of the microtubule network varies according to the plasmodial domain examined. Generally microtubules show no special orientation except in plasmodial veins where they are oriented parallel to the long axis of the veins. Differences between our observations and those of previous workers who failed to find cytoplasmic microtubules in plasmodia are discussed. We propose that they reflect difficulties of observation mainly due to the fluorescent background. In contrast with the previous view, the discovery of a microtubule cytoplasmic cytoskeleton in Physarum plasmodia raises several questions concerning its relationships with other cellular organelles and its dynamics during different cell cycle events.
3
Nunes, Alvaro, Vandana Thathy, Thomas Bruderer, Ali A. Sultan, Ruth S. Nussenzweig, and Robert Ménard. "Subtle Mutagenesis by Ends-in Recombination in Malaria Parasites." Molecular and Cellular Biology 19, no. 4 (April 1, 1999): 2895–902. http://dx.doi.org/10.1128/mcb.19.4.2895.
Full textAbstract:
ABSTRACT The recent advent of gene-targeting techniques in malaria (Plasmodium) parasites provides the means for introducing subtle mutations into their genome. Here, we used the TRAPgene of Plasmodium berghei as a target to test whether an ends-in strategy, i.e., targeting plasmids of the insertion type, may be suitable for subtle mutagenesis. We analyzed the recombinant loci generated by insertion of linear plasmids containing either base-pair substitutions, insertions, or deletions in their targeting sequence. We show that plasmid integration occurs via a double-strand gap repair mechanism. Although sequence heterologies located close (less than 450 bp) to the initial double-strand break (DSB) were often lost during plasmid integration, mutations located 600 bp and farther from the DSB were frequently maintained in the recombinant loci. The short lengths of gene conversion tracts associated with plasmid integration intoTRAP suggests that an ends-in strategy may be widely applicable to modify plasmodial genes and perform structure-function analyses of their important products.
4
SHIRAKAWA, TOMOHIRO, ANDREW ADAMATZKY, YUKIO-PEGIO GUNJI, and YOSHIHIRO MIYAKE. "ON SIMULTANEOUS CONSTRUCTION OF VORONOI DIAGRAM AND DELAUNAY TRIANGULATION BY PHYSARUM POLYCEPHALUM." International Journal of Bifurcation and Chaos 19, no. 09 (September 2009): 3109–17. http://dx.doi.org/10.1142/s0218127409024682.
Full textAbstract:
We experimentally demonstrate that both Voronoi diagram and its dual graph Delaunay triangulation are simultaneously constructed — for specific conditions — in cultures of plasmodium, a vegetative state of Physarum polycephalum. Every point of a given planar data set is represented by a tiny mass of plasmodium. The plasmodia spread from their initial locations but, in certain conditions, stop spreading when they encounter plasmodia originated from different locations. Thus space loci not occupied by the plasmodia represent edges of Voronoi diagram of the given planar set. At the same time, the plasmodia originating at neighboring locations form merging protoplasmic tubes, where the strongest tubes approximate Delaunay triangulation of the given planar set. The problems are solved by plasmodium only for limited data sets, however the results presented lay a sound ground for further investigations.
5
Wu, Yuyang, Peng Xie, Qi Ding, Yuhang Li, Ling Yue, Hong Zhang, and Wei Wang. "Magnetic plasmons in plasmonic nanostructures: An overview." Journal of Applied Physics 133, no. 3 (January 21, 2023): 030902. http://dx.doi.org/10.1063/5.0131903.
Full textAbstract:
The magnetic response of most natural materials, characterized by magnetic permeability, is generally weak. Particularly, in the optical range, the weakness of magnetic effects is directly related to the asymmetry between electric and magnetic charges. Harnessing artificial magnetism started with a pursuit of metamaterial design exhibiting magnetic properties. The first demonstration of artificial magnetism was given by a plasmonic nanostructure called split-ring resonators. Engineered circulating currents form magnetic plasmons, acting as the source of artificial magnetism in response to external electromagnetic excitation. In the past two decades, magnetic plasmons supported by plasmonic nanostructures have become an active topic of study. This Perspective reviews the latest studies on magnetic plasmons in plasmonic nanostructures. A comprehensive summary of various plasmonic nanostructures supporting magnetic plasmons, including split-ring resonators, metal–insulator–metal structures, metallic deep groove arrays, and plasmonic nanoclusters, is presented. Fundamental studies and applications based on magnetic plasmons are discussed. The formidable challenges and the prospects of the future study directions on developing magnetic plasmonic nanostructures are proposed.
6
Honkonen, I., M. Palmroth, T. I. Pulkkinen, P. Janhunen, and A. Aikio. "On large plasmoid formation in a global magnetohydrodynamic simulation." Annales Geophysicae 29, no. 1 (January 14, 2011): 167–79. http://dx.doi.org/10.5194/angeo-29-167-2011.
Full textAbstract:
Abstract. We investigate plasmoid formation in the magnetotail using the global magnetohydrodynamic (MHD) simulation GUMICS-4. Here a plasmoid implies a major reconfiguration of the magnetotail where a part of the tail plasma sheet is ejected downstream, in contrast to small Earthward-propagating plasmoids. We define a plasmoid based solely on the structure of the closed (connected to the Earth at both ends) magnetic field line region. In this definition a plasmoid is partly separated from the ordinary closed field line region by lobe field lines or interplanetary field lines resulting from lobe reconnection. We simulate an event that occurred on 18 February 2004 during which four intensifications of the auroral electroject (AE) index occurred in 8 h. Plasmoids form in the simulation for two of the four AE intensifications. Each plasmoid forms as a result of two consecutive large and fast rotations of the interplanetary magnetic field (IMF). In both cases the IMF rotates 180 degrees at 10 degrees per minute, first from southward to northward and some 15 min later from northward to southward. The other two AE intencifications however are not associated with a plasmoid formation. A plasmoid does not form if either the IMF rotation speed or the angular change of the rotation are small. We also present an operational definition for these fully connected plasmoids that enables their automatic detection in simulations. Finally, we show mappings of the plasmoid footpoints in the ionosphere, where they perturb the polar cap boundary in both hemispheres.
7
Suzuki, Y., T. H. Watanabe, A. Kageyama, T. Sato, and T. Hayashi. "Three-Dimensional Simulation Study of Plasmoid Injection into Magnetized Plasma." Symposium - International Astronomical Union 188 (1998): 209–10. http://dx.doi.org/10.1017/s0074180900114780.
Full textAbstract:
Resent observations suggest that, during solar flares, plasmoids are injected into the interplanetary medium (Stewart et al., 1982). It has also been pointed out that solar wind irregularities modeled as plasmoids are penetrated into the magnetosphere (Lemaire, 1977). These plasmoid injections are considered to be an important process because they transfer mass, momentum, and energy into such magnetized plasma regions. Our objective is to investigate the dynamics of a plasmoid, which is injected into a magnetized plasma region and to reveal mechanisms to transfer them. To achieve this, we carried out three-dimensional magnetohydrodynamic (MHD) simulations.
8
He, Zhicong, Fang Li, Yahui Liu, Fuqiang Yao, Litu Xu, Xiaobo Han, and Kai Wang. "Principle and Applications of the Coupling of Surface Plasmons and Excitons." Applied Sciences 10, no. 5 (March 4, 2020): 1774. http://dx.doi.org/10.3390/app10051774.
Full textAbstract:
Surface plasmons have been attracting increasing attention and have been studied extensively in recent decades because of their half-light and half-material polarized properties. On the one hand, the tightly confined surface plasmonic mode may reduce the size of integrated optical devices beyond the diffraction limit; on the other hand, it provides an approach toward enhancement of the interactions between light and matter. In recent experiments, researchers have realized promising applications for surface plasmons in quantum information processing, ultra-low-power lasers, and micro-nano processing devices by using plasmonic structures, which have demonstrated their superiority over traditional optics structures. In this paper, we introduce the theoretical principle of surface plasmons and review the research work related to the interactions between plasmons and excitons. Some perspectives with regard to the future development of plasmonic coupling are also outlined.
9
Solnica-Krezel, L., M. Diggins-Gilicinski, T. G. Burland, and W. F. Dove. "Variable pathways for developmental changes in composition and organization of microtubules in Physarum polycephalum." Journal of Cell Science 96, no. 3 (July 1, 1990): 383–93. http://dx.doi.org/10.1242/jcs.96.3.383.
Full textAbstract:
The development of uninucleate amoebae into multinucleate plasmodia in myxomycetes is called the amoebal-plasmodial transition (APT). During the APT in Physarum polycephalum the ability to form flagellar axonemes is lost; the astral, open mitosis is replaced by the anastral, closed mitosis; and cytoskeletal microtubules disappear. These changes are accompanied by alterations in the repertoire of expressed tubulins. Using immunofluorescence microscopy we have studied the timing of loss and accumulation of developmentally regulated tubulin isotypes in relation to other cellular events during the APT. We specifically asked whether changes in the composition of microtubules are correlated with changes in their organization. The plasmodium-specific beta 2-tubulin can first be detected in microtubules of uninucleate cells after they become committed to plasmodium formation. However, rare cells are observed that exhibit beta 2-tubulin at earlier or only at later stages of development. Amoeba-specific acetylated alpha 3-tubulin disappears gradually during development. Individual cells differ in the timing of loss of this isotype: alpha 3-tubulin is present in the majority of uninucleate cells, in a fraction of binucleate and quadrinucleate cells, and is absent from larger multinucleate cells. Cytoplasmic microtubules in uninucleate cells are organized by a single microtubule-organizing center (MTOC) juxtaposed to the nucleus. Binucleate cells and quadrinucleate cells exhibit variable numbers of MTOCs. Cytoplasmic microtubules persist during the APT until the stage of plasmodia containing at least 100 nuclei. The lack of a strict correlation between the changes in tubulin composition and changes in organization of microtubular structures indicates that accumulation of beta 2-tubulin and disappearance of alpha 3-tubulin isotypes are not sufficient to bring about reorganization of microtubules during development. Individual cells in a developing population differ not only in the succession of accumulation and loss of developmentally regulated tubulins, but also in the sequences of other cellular changes occurring during the APT.
10
Tao, Z. H., H. M. Dong, and Y. F. Duan. "Anomalous plasmon modes of single-layer MoS2." Modern Physics Letters B 33, no. 18 (June 26, 2019): 1950200. http://dx.doi.org/10.1142/s0217984919502002.
Full textAbstract:
The electronic plasmons of single layer MoS2 induced by different spin subbands owing to spin-orbit couplings (SOCs) are theoretically investigated. The study shows that two new and anomalous plasmonic modes can be achieved via inter-spin subband transitions around the Fermi level due to the SOCs. The plasmon modes are optic-like, which are very different from the plasmons reported recently in single-layer (SL) MoS2, and the other two-dimensional systems. The frequency of such plasmons ascends with the increasing of electron density or spin polarizability, and decreases with the increasing of wave vector. The promising plasmonic properties of SL MoS2 make it interesting for future applications in plasmonic and terahertz devices.
11
Diggins-Gilicinski, M., L. Solnica-Krezel, T. G. Burland, E. C. Paul, and W. F. Dove. "The localization of the divergent beta 2-tubulin isotype in the microtubular arrays of Physarum polycephalum." Journal of Cell Science 94, no. 2 (October 1, 1989): 217–26. http://dx.doi.org/10.1242/jcs.94.2.217.
Full textAbstract:
The beta 2-tubulin isotype of Physarum polycephalum is only 83% identical in amino acid sequence with the constitutively expressed beta 1B-tubulin and the myxamoeba-specific beta 1A-tubulin isotypes. A polyclonal antibody specific for beta 2-tubulin was used to monitor the subcellular distribution of the beta 2-tubulin antigen in the mitotic spindle of the mature plasmodium - the sole microtubular array in that stage of Physarum. By immunofluorescence, the beta 2-tubulin antigen was detected throughout this anastral mitotic spindle, at all stages of mitosis. Physarum myxamoebae contain astral mitotic spindles and cytoskeletal microtubules. No beta 2-tubulin antigen was detected in the myxamoebal stage. However, as cultures of myxamoebae developed into plasmodia, the beta 2-tubulin antigen was found in the astral mitotic spindles and cytoskeletons in developing cells. Thus, the presence of the plasmodial beta 2-tubulin isotype in a mitotic spindle does not determine a closed, anastral mitosis.
12
Pancerz, Krzysztof, and Andrew Schumann. "Slime Mould Games Based on Rough Set Theory." International Journal of Applied Mathematics and Computer Science 28, no. 3 (September 1, 2018): 531–44. http://dx.doi.org/10.2478/amcs-2018-0041.
Full textAbstract:
Abstract We define games on the medium of plasmodia of slime mould, unicellular organisms that look like giant amoebae. The plasmodia try to occupy all the food pieces they can detect. Thus, two different plasmodia can compete with each other. In particular, we consider game-theoretically how plasmodia of Physarum polycephalum and Badhamia utricularis fight for food. Placing food pieces at different locations determines the behavior of plasmodia. In this way, we can program the plasmodia of Physarum polycephalum and Badhamia utricularis by placing food, and we can examine their motion as a Physarum machine-an abstract machine where states are represented as food pieces and transitions among states are represented as movements of plasmodia from one piece to another. Hence, this machine is treated as a natural transition system. The behavior of the Physarum machine in the form of a transition system can be interpreted in terms of rough set theory that enables modeling some ambiguities in motions of plasmodia. The problem is that there is always an ambiguity which direction of plasmodium propagation is currently chosen: one or several concurrent ones, i.e., whether we deal with a sequential, concurrent or massively parallel motion. We propose to manage this ambiguity using rough set theory. Firstly, we define the region of plasmodium interest as a rough set; secondly, we consider concurrent transitions determined by these regions as a context-based game; thirdly, we define strategies in this game as a rough set; fourthly, we show how these results can be interpreted as a Go game.
13
Politano, Antonio, and Gennaro Chiarello. "Plasmon modes in graphene: status and prospect." Nanoscale 6, no. 19 (2014): 10927–40. http://dx.doi.org/10.1039/c4nr03143a.
Full text
14
Christie, I. M., M. Petropoulou, L. Sironi, and D. Giannios. "Interplasmoid Compton scattering and the Compton dominance of BL Lacs." Monthly Notices of the Royal Astronomical Society 492, no. 1 (December 9, 2019): 549–55. http://dx.doi.org/10.1093/mnras/stz3265.
Full textAbstract:
ABSTRACT Blazar emission models based on magnetic reconnection succeed in reproducing many observed spectral and temporal features, including the short-duration luminous flaring events. Plasmoids, a self-consistent by-product of the tearing instability in the reconnection layer, can be the main source of blazar emission. Kinetic simulations of relativistic reconnection have demonstrated that plasmoids are characterized by rough energy equipartition between their radiating particles and magnetic fields. This is the main reason behind the apparent shortcoming of plasmoid-dominated emission models to explain the observed Compton ratios of BL Lac objects. Here, we demonstrate that the radiative interactions among plasmoids, which have been neglected so far, can assist in alleviating this contradiction. We show that photons emitted by large, slow-moving plasmoids can be a potentially important source of soft photons to be then upscattered, via inverse Compton, by small fast-moving, neighbouring plasmoids. This interplasmoid Compton scattering process can naturally occur throughout the reconnection layer, imprinting itself as an increase in the observed Compton ratios from those short and luminous plasmoid-powered flares within BL Lac sources, while maintaining energy equipartition between radiating particles and magnetic fields.
15
Markidis, S., P. Henri, G. Lapenta, A. Divin, M. V. Goldman, D. Newman, and S. Eriksson. "Collisionless magnetic reconnection in a plasmoid chain." Nonlinear Processes in Geophysics 19, no. 1 (February 27, 2012): 145–53. http://dx.doi.org/10.5194/npg-19-145-2012.
Full textAbstract:
Abstract. The kinetic features of plasmoid chain formation and evolution are investigated by two dimensional Particle-in-Cell simulations. Magnetic reconnection is initiated in multiple X points by the tearing instability. Plasmoids form and grow in size by continuously coalescing. Each chain plasmoid exhibits a strong out-of plane core magnetic field and an out-of-plane electron current that drives the coalescing process. The disappearance of the X points in the coalescence process are due to anti-reconnection, a magnetic reconnection where the plasma inflow and outflow are reversed with respect to the original reconnection flow pattern. Anti-reconnection is characterized by the Hall magnetic field quadrupole signature. Two new kinetic features, not reported by previous studies of plasmoid chain evolution, are here revealed. First, intense electric fields develop in-plane normally to the separatrices and drive the ion dynamics in the plasmoids. Second, several bipolar electric field structures are localized in proximity of the plasmoid chain. The analysis of the electron distribution function and phase space reveals the presence of counter-streaming electron beams, unstable to the two stream instability, and phase space electron holes along the reconnection separatrices.
16
Akhavan-Niaki, H., L. Mir, M. L. Oustrin, A. Moisand, and M. Wright. "Genetic analysis of the relationships between the amoebal extranuclear spindle-organizing centre and the plasmodial intranuclear spindle-organizing centre of Physarum during conjugation." Journal of Cell Science 99, no. 2 (June 1, 1991): 265–71. http://dx.doi.org/10.1242/jcs.99.2.265.
Full textAbstract:
Physarum amoebae possess an extranuclear spindle-organizing centre (abbreviated SPOC), located in a typical centrosome with a pair of associated centrioles while plasmodia possess an intranuclear SPOC without centrioles. In order to ascertain whether, during conjugation, the plasmodial SPOC is derived from the amoebal one or is not related to it, we have constructed amoebal strains possessing two and three SPOCs and we have used as a genetic marker the frequency of polycentric metaphases in order to evaluate the number of SPOCs in the plasmodia. The results of both symmetrical crosses, i.e. between amoebae possessing the same number of SPOCs, and asymmetrical crosses, i.e. between amoebae possessing a different number of SPOCs, show that: (1) the number of SPOCs in plasmodia is dependent upon the number of SPOCs in either one of the two parental amoeba; (2) in no cross does the number of plasmodial SPOCs equal the sum of the parental amoebal SPOCs, but it corresponds to that of only one parent without any polarity of transmission in asymmetrical crosses. These results are consistent with the following model: (1) plasmodial SPOCs are derived from the amoebal ones; and (2) one set of parental SPOCs is lost, destroyed or inactivated in the zygote.
17
Lemaire, J. "Plasmoid motion across a tangential discontinuity (with application to the magnetopause)." Journal of Plasma Physics 33, no. 3 (June 1985): 425–36. http://dx.doi.org/10.1017/s0022377800002592.
Full textAbstract:
The motion of a plasmoid (plasma-field entity) across an inhomogeneous magnetic field distribution of which the direction and strength change along the penetration trajectory has been studied. The bulk velocity decreases when the plasma element penetrates into a region of increasing magnetic field. The critical magnetic field intensity where a plasmoid is stopped or deflected is found to be the same critical field as that which has been observed in laboratory experiments for a non-rotating B-field distribution. The polarization electric field induced inside a moving plasma element has been determined for both low-β and high-β plasmoids. The momentum density vector of a plasmoid is deflected in the – B × ∇B and – B × (B. ∇)B directions as it penetrates into an inhomogeneous B-field distribution. This kinetic model has been applied to the impulsive penetration of solar wind plasma irregularities impinging on the earth's geomagnetic field with an excess momentum density. As a consequence of impulsive penetration, a plasma boundary layer is formed where the intruding plasmoids are deflected eastward. Magnetospheric plasma is dragged in the direction parallel to the flanks of the average magnetopause surface. Diamagnetic effects of these impulsively penetrating plasmoids into the magnetosphere are also briefly discussed.
18
Hu, Bin, Ying Zhang, and Qi Jie Wang. "Surface magneto plasmons and their applications in the infrared frequencies." Nanophotonics 4, no. 4 (November 6, 2015): 383–96. http://dx.doi.org/10.1515/nanoph-2014-0026.
Full textAbstract:
Abstract Due to their promising properties, surface magneto plasmons have attracted great interests in the field of plasmonics recently. Apart from flexible modulation of the plasmonic properties by an external magnetic field, surface magneto plasmons also promise nonreciprocal effect and multi-bands of propagation, which can be applied into the design of integrated plasmonic devices for biosensing and telecommunication applications. In the visible frequencies, because it demands extremely strong magnetic fields for the manipulation of metallic plasmonic materials, nano-devices consisting of metals and magnetic materials based on surface magneto plasmon are difficult to be realized due to the challenges in device fabrication and high losses. In the infrared frequencies, highly-doped semiconductors can replace metals, owning to the lower incident wave frequencies and lower plasma frequencies. The required magnetic field is also low, which makes the tunable devices based on surface magneto plasmons more practically to be realized. Furthermore, a promising 2D material-graphene shows great potential in infrared magnetic plasmonics. In this paper, we review the magneto plasmonics in the infrared frequencies with a focus on device designs and applications. We investigate surface magneto plasmons propagating in different structures, including plane surface structures and slot waveguides. Based on the fundamental investigation and theoretical studies, we illustrate various magneto plasmonic micro/nano devices in the infrared, such as tunable waveguides, filters, and beam-splitters. Novel plasmonic devices such as one-way waveguides and broad-band waveguides are also introduced.
19
Frame, I. J., Emilio F. Merino, Vern L. Schramm, María B. Cassera, and Myles H. Akabas. "Malaria parasite type 4 equilibrative nucleoside transporters (ENT4) are purine transporters with distinct substrate specificity." Biochemical Journal 446, no. 2 (August 14, 2012): 179–90. http://dx.doi.org/10.1042/bj20112220.
Full textAbstract:
Malaria, caused by Plasmodia parasites, affects hundreds of millions of people. As purine auxotrophs, Plasmodia use transporters to import host purines for subsequent metabolism by the purine salvage pathway. Thus purine transporters are attractive drug targets. All sequenced Plasmodia genomes encode four ENTs (equilibrative nucleoside transporters). During the pathogenic intraerythrocytic stages, ENT1 is a major route of purine nucleoside/nucleobase transport. Another plasma membrane purine transporter exists because Plasmodium falciparum ENT1-knockout parasites survive at supraphysiological purine concentrations. The other three ENTs have not been characterized functionally. Codon-optimized Pf- (P. falciparum) and Pv- (Plasmodium vivax) ENT4 were expressed in Xenopus laevis oocytes and substrate transport was determined with radiolabelled substrates. ENT4 transported adenine and 2′-deoxyadenosine at the highest rate, with millimolar-range apparent affinity. ENT4-expressing oocytes did not accumulate hypoxanthine, a key purine salvage pathway substrate, or AMP. Micromolar concentrations of the plant hormone cytokinin compounds inhibited both PfENT4 and PvENT4. In contrast with PfENT1, ENT4 interacted with the immucillin compounds in the millimolar range and was inhibited by 10 μM dipyridamole. Thus ENT4 is a purine transporter with unique substrate and inhibitor specificity. Its role in parasite physiology remains uncertain, but is likely to be significant because of the strong conservation of ENT4 homologues in Plasmodia genomes.
20
Wel, Anna M. van der, Ana M. Tomás, Clemens H. M. Kocken, Pawan Malhotra, Chris J. Janse, Andrew P. Waters, and Alan W. Thomas. "Transfection of the Primate Malaria Parasite Plasmodium knowlesi Using Entirely Heterologous Constructs." Journal of Experimental Medicine 185, no. 8 (April 21, 1997): 1499–504. http://dx.doi.org/10.1084/jem.185.8.1499.
Full textAbstract:
The recently developed transfection systems for Plasmodium berghei and Plasmodium falciparum offer important new tools enabling further insight into the biology of malaria parasites. These systems rely upon artificial parasite–host combinations which do not allow investigation into the complex interactions between parasites and their natural hosts. Here we report on stable transfection of Plasmodium knowlesi (a primate malaria parasite that clusters phylogenetically with P. vivax) for which both natural and artificial experimental hosts are available. Transfection of this parasite offers the opportunity to further analyze the biology of antigens not only in a natural host but also in hosts that are closely related to humans. To facilitate future development of integration-dependent transfection in P. knowlesi, completely heterologous plasmids that would reduce homologous recombination at unwanted sites in the genome were constructed. These plasmids contained the pyrimethamine-resistant form of dihydrofolate reductase-thymidylate synthase (dhfr-ts) from Toxoplasma gondii or P. berghei, under control of either (a) P. berghei or (b) P. falciparum promoters. Plasmids were electroporated into mature P. knowlesi schizonts and these cells were injected into rhesus monkeys (Macaca mulatta). After pyrimethamine treatment of these monkeys, resistant parasites were obtained that contained the plasmids. Promoter regions of both P. berghei and P. falciparum controlling dhfr-ts expression were effective in conferring pyrimethamine resistance in P. knowlesi, indicating that common signals control gene expression in phylogenetically distant Plasmodium species.
21
Pallotta, Dominick, André Laroche, Anne Tessier, Thomas Shinnick, and Gérald Lemieux. "Molecular cloning of stage specific mRNAs from amoebae and Plasmodia of Physarum polycephalum." Biochemistry and Cell Biology 64, no. 12 (December 1, 1986): 1294–302. http://dx.doi.org/10.1139/o86-170.
Full textAbstract:
We constructed cDNA libraries from plasmodia and amoebal poly(A)+ RNA of Physarum polycephalum. The libraries were screened by differential hybridization with labeled poly(A)+ RNA of amoebae and plasmodia. The 136 plasmodial specific clones that gave the strongest hybridization signals were analysed in detail. From this group six different cDNA sequences were found. Four of the cDNAs each accounted for between 1 and 4.8% of all the clones in the library and represented abundant mRNAs. Two other clones constituted 0.2 and 0.4% of the total library. Seventeen clones in the amoebal library were amoebal specific. From these clones, seven different sequences were found. One of the sequences was present in nine clones (1.2%) of the library and considered abundant. The other six sequences were each found in only one or two clones. The specificity of these amoebal and plasmodial mRNAs was confirmed by Northern hybridization. Our results show that amoebae and plasmodia have different mRNA populations, which are most likely the result of differential gene expression in these two developmental stages.
22
Schumann, Andrew. "Towards Slime Mould Based Computer." New Mathematics and Natural Computation 12, no. 02 (June 8, 2016): 97–111. http://dx.doi.org/10.1142/s1793005716500083.
Full textAbstract:
In this paper, I theoretically summarize, which behavioral possibilities the plasmodium of Physarum polycephalum has in order to be considered the medium of computation. I show that plasmodia can be represented as a natural implementation of different abstract automata: cellular automata, Kolmogorov–Uspensky machines, Schönhage’s storage modification machines, random-access machines. As a programming language for simulating Physarum plasmodium behavior, process calculus can be used.
23
AHMAD, Nisar, Ping ZHU, Ahmad ALI, and Shiyong ZENG. "Viscous effects on plasmoid formation from nonlinear resistive tearing growth in a Harris sheet." Plasma Science and Technology 24, no. 1 (November 23, 2021): 015103. http://dx.doi.org/10.1088/2058-6272/ac3563.
Full textAbstract:
Abstract In this work, the evolution of a highly unstable m = 1 resistive tearing mode, leading to plasmoid formation in a Harris sheet, is studied in the framework of full MHD model using the Non-Ideal Magnetohydrodynamics with Rotation, Open Discussion simulation. Following the initial nonlinear growth of the primary m = 1 island, the X-point develops into a secondary elongated current sheet that eventually breaks into plasmoids. Two distinctive viscous regimes are found for the plasmoid formation and saturation. In the low viscosity regime (i.e. P r ≲ 1), the plasmoid width increases sharply with viscosity, whereas in the viscosity dominant regime (i.e. P r ≳ 1), the plasmoid size gradually decreases with viscosity. Such a finding quantifies the role of viscosity in modulating the plasmoid formation process through its effects on the plasma flow and the reconnection itself.
24
AL-Kinani, Zahraa Ibrahim, and Firas Faeq K. Hussain. "A Review of Plasmonic Photonic Crystal Fiber." Muthanna Journal of Pure Science 7, no. 2 (October 14, 2020): 38–66. http://dx.doi.org/10.52113/2/07.02.2020/38-66.
Full textAbstract:
"Nanophotonics technology is the study of the confinement of electromagnetic fields on a subwavelength scale and surface plasmons plays a major role in advancing this arising field. They can take various forms, ranging from freely propagating electron density waves along metal surfaces to localized electron oscillations on metal nanoparticles. The interaction between the free electrons' oscillations and electromagnetic waves of light gives the surface plasmons their appealing characteristics. Their ability of light confinement and propagation through subwavelength structures grants the construction of photonic devices with minimum size, hence the characterize and design of plasmonic devices can be resolved using numerical simulation. This review starts with general introduction about Plasmonic photonic crystal fiber. This is followed by a historical background and literature review of Plasmonic PCF. Some types of designs are illustrated. Finally, the applications of Plasmonic PCF are mentioned dependent on the types of design including the circular plasmonic photonic crystal fiber technique.
25
Dembélé, Laurent, Jean-François Franetich, Valérie Soulard, Nadia Amanzougaghene, Shahin Tajeri, Teun Bousema, Geert-Jan van Gemert, et al. "Chloroquine Potentiates Primaquine Activity against Active and Latent Hepatic Plasmodia Ex Vivo: Potentials and Pitfalls." Antimicrobial Agents and Chemotherapy 65, no. 1 (October 19, 2020): e01416-20. http://dx.doi.org/10.1128/aac.01416-20.
Full textAbstract:
ABSTRACTFor a long while, 8-aminoquinoline compounds have been the only therapeutic agents against latent hepatic malaria parasites. These have poor activity against the blood-stage plasmodia causing acute malaria and must be used in conjunction with partner blood schizontocidal agents. We examined the impacts of one such agent, chloroquine, upon the activity of primaquine, an 8-aminoquinoline, against hepatic stages of Plasmodium cynomolgi, Plasmodium yoelii, Plasmodium berghei, and Plasmodium falciparum within several ex vivo systems—primary hepatocytes of Macaca fascicularis, primary human hepatocytes, and stably transformed human hepatocarcinoma cell line HepG2. Primaquine exposures to formed hepatic schizonts and hypnozoites of P. cynomolgi in primary simian hepatocytes exhibited similar 50% inhibitory concentration (IC50) values near 0.4 μM, whereas chloroquine in the same system exhibited no inhibitory activities. Combining chloroquine and primaquine in this system decreased the observed primaquine IC50 for all parasite forms in a chloroquine dose-dependent manner by an average of 18-fold. Chloroquine also decreased the primaquine IC50 against hepatic P. falciparum in primary human hepatocytes, P. berghei in simian primary hepatocytes, and P. yoelii in primary human hepatocytes. Chloroquine had no impact on primaquine IC50 against P. yoelii in HepG2 cells and, likewise, had no impact on the IC50 of atovaquone (hepatic schizontocide) against P. falciparum in human hepatocytes. We describe important sources of variability in the potentiation of primaquine activity by chloroquine in these systems. Chloroquine potentiated primaquine activity against hepatic forms of several plasmodia. We conclude that chloroquine specifically potentiated 8-aminoquinoline activities against active and dormant hepatic-stage plasmodia in normal primary hepatocytes but not in a hepatocarcinoma cell line.
26
Rakoczy, Leokadia, Andrzej Majcherczyk, and Aloys Hüttermann. "Changes in plasmodial pigments of Physarum polycephalum in relation to the age of the culture." Canadian Journal of Microbiology 33, no. 3 (March 1, 1987): 217–20. http://dx.doi.org/10.1139/m87-037.
Full textAbstract:
Plasmodia of the myxomycete Physarum polycephalum were grown in the dark on a semidefined medium and pigments were assayed from cultures of different ages. The absorption of the crude pigment extracts, measured at the maximum, increased with an increase in the growth rate of the organisms, but with a time lag of about 2 days when compared to increases in the plasmodial protein content. Anaylses of pigments were performed with a newly elaborated HPLC method, and eight pigments, monitored at 382 m, were obtained from the different aged plasmodia. Throughout the culture, quantitative changes in the pigments were found which could be described as periodical. Individual pigments varied in their quantitative changes. In prolonged culture the amount of two pigments significantly increased, in comparison with the other colored compounds, and attained their maximum values after plasmodial growth ceased.
27
Dubowsky, Scott E., Amber N. Rose, Nick G. Glumac, and Benjamin J. McCall. "Electrical Properties of Reversed-Polarity Ball Plasmoid Discharges." Plasma 3, no. 3 (June 29, 2020): 92–102. http://dx.doi.org/10.3390/plasma3030008.
Full textAbstract:
Ball plasmoid discharges are a unique type of atmospheric-pressure plasma discharge with a lifetime on the order of a hundred milliseconds without attachment to a power source. These discharges are generated by a moderate current pulse over the surface of an aqueous electrolyte, and some consider the spherical plasmoid that results to bear some resemblance to ball lightning. This article presents the first analysis of the electrical properties of ball plasmoid discharges in a reversed-polarity configuration, i.e., with the central electrode serving as the anode rather than as the cathode. These experiments demonstrate that ball plasmoids can indeed be generated with either electrode polarity with similar observable properties. These results are contrary to what has previously been discussed in the literature and raise additional questions regarding formation mechanisms of ball plasmoids. Analysis of images and electrical measurements collected at various discharge energies show that two distinct processes occur during discharges with our circuitry and in this reversed-polarity configuration: the formation of spark channels between the anode and electrolyte, and the generation of streamers and a jet from the surface of the anode.
28
Belehaki, A., R. W. McEntire, S. Kokubun, and T. Yamamoto. "Magnetotail response during a strong substorm as observed by GEOTAIL in the distant tail." Annales Geophysicae 16, no. 5 (May 31, 1998): 528–41. http://dx.doi.org/10.1007/s00585-998-0528-5.
Full textAbstract:
Abstract. Simultaneous energetic particle and magnetic field observations from the GEOTAIL spacecraft in the distant tail (XGSM≈ –150 Re) have been analysed to study the response of the Earth's magnetotail during a strong substorm (AE ≤ 680 nT). At geosynchronous altitude, LANL spacecraft recorded three electron injections between 0030 UT and 0130 UT, which correspond to onsets observed on the ground at Kiruna Ground Observatory. The Earth's magnetotail responded to this substorm with the ejection of five plasmoids, whose size decreases from one plasmoid to the next. Since the type of magnetic structure detected by a spacecraft residing the lobes, depends on the Z extent of the structure passing underneath the spacecraft, GEOTAIL is first engulfed by a plasmoid structure; six minutes later it detects a boundary layer plasmoid (BLP) and finally at the recovery phase of the substorm GEOTAIL observes three travelling compression regions (TCRs). The time-of-flight (TOF) speed of these magnetic structures was estimated to range between 510 km/s and 620 km/s. The length of these individual plasmoids was calculated to be between 28 Re and 56 Re. The principal axis analysis performed on the magnetic field during the TCR encountered, has confirmed that GEOTAIL observed a 2-D perturbation in the X-Z plane due to the passage of a plasmoid underneath. The first large plasmoid that engulfed GEOTAIL was much more complicated in nature probably due to the external, variable draped field lines associated with high beta plasma sheet and the PSBL flux tubes surrounding the plasmoid. From the analysis of the energetic particle angular distribution, evidence was found that ions were accelerated from the distant X-line at the onset of the burst associated with the first magnetic structure. Key words. Magnetospheric physics (magnetospheric configuration and dynamics; magnetotail).
29
Nong, Jinpeng, Linlong Tang, Guilian Lan, Peng Luo, Caicheng Guo, Juemin Yi, and Wei Wei. "Wideband tunable perfect absorption of graphene plasmons via attenuated total reflection in Otto prism configuration." Nanophotonics 9, no. 3 (January 28, 2020): 645–55. http://dx.doi.org/10.1515/nanoph-2019-0400.
Full textAbstract:
AbstractA strategy is proposed to achieve wideband tunable perfect plasmonic absorption in graphene nanoribbons by employing attenuated total refraction (ATR) in Otto prism configuration. In this configuration, the Otto prism with a deep-subwavelength dielectric spacer is used to generate tunneling evanescent waves to excite localized plasmons in graphene nanoribbons. The influence of the configuration parameters on the absorption spectra of graphene plasmons is studied systematically, and the key finding is that perfect absorption can be achieved by actively controlling the incident angle of light under ATR conditions, which provides an effective degree of freedom to tune the absorption properties of graphene plasmons. Based on this result, it is further demonstrated that by simultaneously tuning the incident angle and the graphene Fermi energy, the tunable absorption waveband can be significantly enlarged, which is about 3 times wider than the conventional cavity-enhanced configuration. Our proposed strategy to achieve wideband, tunable graphene plasmons could be useful in various infrared plasmonic devices.
30
Raja Yahya, Mohd Fakharul Zaman, and Hasidah Mohd Sidek. "Comparative Study on Mitogen Activated Protein Kinase of Plasmodium Species by Using In silico Method." Scientific Research Journal 9, no. 1 (June 30, 2012): 1. http://dx.doi.org/10.24191/srj.v9i1.5052.
Full textAbstract:
Malaria parasites, Plasmodium can infect a wide range ofhosts including humans and rodents. There are two copies ofmitogen activated protein kinases (MAPKs) in Plasmodium, namely MAPK1 and MAPK2. The MAPKs have been studied extensively in the human Plasmodium, P. falciparum. However, the MAPKs from other Plasmodium species have not been characterized and it is therefore the premise ofpresented study to characterize the MAPKs from other Plasmodium species-P. vivax, P. knowlesi, P. berghei, P. chabaudi and P.yoelli using a series ofpublicly available bioinformatic tools. In silico data indicates that all Plasmodium MAPKs are nuclear-localizedandcontain both a nuclear localization signal (NLS) anda Leucine-rich nuclear export signal (NES). The activation motifs ofTDYand TSH werefound to befully conserved in Plasmodium MAPK1 and MAPK2, respectively. The detailed manual inspection ofa multiple sequence alignment (MSA) construct revealed a total of 17 amino acid stack patterns comprising ofdifferent amino acids present in MAPK1 and MAPK2 respectively, with respect to rodent and human Plasmodia. 1t is proposed that these amino acid stack patterns may be useful in explaining the disparity between rodent and human Plasmodium MAPKs.
31
Tohari, Mariam M., Andreas Lyras, and Mohamad S. AlSalhi. "A Novel Metal Nanoparticles-Graphene Nanodisks-Quantum Dots Hybrid-System-Based Spaser." Nanomaterials 10, no. 3 (February 27, 2020): 416. http://dx.doi.org/10.3390/nano10030416.
Full textAbstract:
Active nanoplasmonics have recently led to the emergence of many promising applications. One of them is the spaser (surface plasmons amplification by stimulated emission of radiation) that has been shown to generate coherent and intense fields of selected surface plasmon modes that are strongly localized in the nanoscale. We propose a novel nanospaser composed of a metal nanoparticles-graphene nanodisks hybrid plasmonic system as its resonator and a quantum dots cascade stack as its gain medium. We derive the plasmonic fields induced by pulsed excitation through the use of the effective medium theory. Based on the density matrix approach and by solving the Lindblad quantum master equation, we analyze the ultrafast dynamics of the spaser associated with coherent amplified plasmonic fields. The intensity of the plasmonic field is significantly affected by the width of the metallic contact and the time duration of the laser pulse used to launch the surface plasmons. The proposed nanospaser shows an extremely low spasing threshold and operates in the mid-infrared region that has received much attention due to its wide biomedical, chemical and telecommunication applications.
32
Wang, Jiyong, Emre Gürdal, Anke Horneber, Simon Dickreuter, Sergei Kostcheev, Alfred J. Meixner, Monika Fleischer, Pierre-Michel Adam, and Dai Zhang. "Carrier recombination and plasmonic emission channels in metallic photoluminescence." Nanoscale 10, no. 17 (2018): 8240–45. http://dx.doi.org/10.1039/c7nr07821h.
Full text
33
Silverman, PH, JC Schooley, and LJ Mahlmann. "Murine malaria decreases hemopoietic stem cells." Blood 69, no. 2 (February 1, 1987): 408–13. http://dx.doi.org/10.1182/blood.v69.2.408.408.
Full textAbstract:
Abstract The causes of anemia and immunosuppression, major outcomes of malaria, are not well established. This study was undertaken to investigate whether erythropoietin (EP) production is adequate and whether the hemopoietic stem cells (CFU-S) were affected during the course of infection. Groups of female Balb/c mice infected with Plasmodium vinckei vinckei, Plasmodium berghei, or Plasmodium chabaudi adami were exposed to five hours of simulated altitude equivalent to 22,000 ft. Plasma samples were collected for EP bioassay and radioimmunoassay (RIA). Using radioiron incorporation as an index of erythropoiesis, differences in response to infection with different species of plasmodia were observed. In general, decreases in erythropoietic activity were observed in bone marrow and spleen as the infection progressed and continued to be depressed after apparent resolution of a nonlethal infection with P. chabaudi adami. Marrow from infected and control femurs were tested for CFU-S content using the spleen colony assay. The cellularity and CFU-S content of the femoral marrow decrease as the parasitemia increases. All three species of plasmodia stimulate EP production during peak parasitemias, indicating that adequate amounts of EP are available to the erythron during malarial infection. Depletion of CFU-S and probable lack of compensatory turnover of CFU-S may contribute to the disease characteristics of malaria.
34
Silverman, PH, JC Schooley, and LJ Mahlmann. "Murine malaria decreases hemopoietic stem cells." Blood 69, no. 2 (February 1, 1987): 408–13. http://dx.doi.org/10.1182/blood.v69.2.408.bloodjournal692408.
Full textAbstract:
The causes of anemia and immunosuppression, major outcomes of malaria, are not well established. This study was undertaken to investigate whether erythropoietin (EP) production is adequate and whether the hemopoietic stem cells (CFU-S) were affected during the course of infection. Groups of female Balb/c mice infected with Plasmodium vinckei vinckei, Plasmodium berghei, or Plasmodium chabaudi adami were exposed to five hours of simulated altitude equivalent to 22,000 ft. Plasma samples were collected for EP bioassay and radioimmunoassay (RIA). Using radioiron incorporation as an index of erythropoiesis, differences in response to infection with different species of plasmodia were observed. In general, decreases in erythropoietic activity were observed in bone marrow and spleen as the infection progressed and continued to be depressed after apparent resolution of a nonlethal infection with P. chabaudi adami. Marrow from infected and control femurs were tested for CFU-S content using the spleen colony assay. The cellularity and CFU-S content of the femoral marrow decrease as the parasitemia increases. All three species of plasmodia stimulate EP production during peak parasitemias, indicating that adequate amounts of EP are available to the erythron during malarial infection. Depletion of CFU-S and probable lack of compensatory turnover of CFU-S may contribute to the disease characteristics of malaria.
35
Zhou, Y., M. N. Chen, M. D. Zhao, F. Tang, C. Q. Shao, and M. Y. Dai. "Unusual plasmonic responses in phosphorene with topological transition: the interplay of strain and doping." New Journal of Physics 23, no. 11 (November 1, 2021): 113036. http://dx.doi.org/10.1088/1367-2630/ac3554.
Full textAbstract:
Abstract In this paper, plasmonic responses of phosphorene in the presence of strain and doping have been systematically investigated. Based on density functional theory, permittivities include both the intraband and interband transitions of electrons have been calculated. Due to the modification of the band structure, significantly higher Drude plasma frequency has been observed along the zigzag direction, other than the armchair direction as in the usual case. The resulting unusual plasmonic responses change their anisotropy, both in the elliptic as well as the hyperbolic regimes. Based on our calculations, positive strain as large as 5% along the zigzag direction can even lead to so-called reversed hyperbolic plasmonic responses. The k-surfaces of the plasmonic modes in extended monolayer have been analytically solved, and it is found that actively switching the topology (between elliptic and hyperbolic regimes) of the plasmonic responses by changing the Fermi level is possible in phosphorene at certain frequencies. In the end, a simple model has been proposed to describe such plasmonic responses in the infrared and the parameters of the model have been listed in tables which can be used directly in calculating the permittivities. Our studies may extend the scope of existing investigations of phosphorene plasmons and lead to band engineering as a way to control plasmons in two-dimensional materials.
36
Karaballi, Reem A., Yashar Esfahani Monfared, Isobel C. Bicket, Robert H. Coridan, and Mita Dasog. "Solid-state synthesis of UV-plasmonic Cr2N nanoparticles." Journal of Chemical Physics 157, no. 15 (October 21, 2022): 154706. http://dx.doi.org/10.1063/5.0109806.
Full textAbstract:
Materials that exhibit plasmonic response in the UV region can be advantageous for many applications, such as biological photodegradation, photocatalysis, disinfection, and bioimaging. Transition metal nitrides have recently emerged as chemically and thermally stable alternatives to metal-based plasmonic materials. However, most free-standing nitride nanostructures explored so far have plasmonic responses in the visible and near-IR regions. Herein, we report the synthesis of UV-plasmonic Cr2N nanoparticles using a solid-state nitridation reaction. The nanoparticles had an average diameter of 9 ± 5 nm and a positively charged surface that yields stable colloidal suspension. The particles were composed of a crystalline nitride core and an amorphous oxide/oxynitride shell whose thickness varied between 1 and 7 nm. Calculations performed using the finite element method predicted the localized surface plasmon resonance (LSPR) for these nanoparticles to be in the UV-C region (100–280 nm). While a distinctive LSPR peak could not be observed using absorbance measurements, low-loss electron energy loss spectroscopy showed the presence of surface plasmons between 80 and 250 nm (or ∼5 to 15 eV) and bulk plasmons centered around 50–62 nm (or ∼20 to 25 eV). Plasmonic coupling was also observed between the nanoparticles, resulting in resonances between 250 and 400 nm (or ∼2.5 to 5 eV).
37
Mithun, K. P., Srabani Kar, Abinash Kumar, D. V. S. Muthu, N. Ravishankar, and A. K. Sood. "Dirac surface plasmons in photoexcited bismuth telluride nanowires: optical pump-terahertz probe spectroscopy." Nanoscale 13, no. 17 (2021): 8283–92. http://dx.doi.org/10.1039/d0nr09087e.
Full text
38
Haskins, E. F. "Occurrence of pseudopodial abstriction in the aphanoplasmodium of Stemonitis flavogenita (Myxomycetes, Stemonitales)." Canadian Journal of Botany 69, no. 11 (November 1, 1991): 2511–14. http://dx.doi.org/10.1139/b91-312.
Full textAbstract:
The first photographic evidence is presented of the derivation of uninucleate, amoeboid cells from aphanoplasmodia of Stemonitis flavogenita. This process, observed only in young plasmodia, involves the abstriction of aphanoplasmodial pseudopodia. The biological ramifications of this phenomenon are discussed. Key words: Stemonitis, Myxomycetes, pseudopodial abstriction, plasmodial to uninucleate amoeboid cell conversion.
39
Antinori, Spinello, Laura Galimberti, Laura Milazzo, and Mario Corbellino. "BIOLOGY OF HUMAN MALARIA PLASMODIA INCLUDING PLASMODIUM KNOWLESI." Mediterranean Journal of Hematology and Infectious Diseases 4, no. 1 (March 9, 2012): e2012013. http://dx.doi.org/10.4084/mjhid.2012.013.
Full textAbstract:
Malaria is a vector-borne infection caused by unicellular parasite of the genus Plasmodium. Plasmodia are obligate intracellular parasites that in humans after a clinically silent replication phase in the liver are able to infect and replicate within the erythrocytes. Four species (P.falciparum, P.malariae, P.ovale and P.vivax) are traditionally recognized as responsible of natural infection in human beings but the recent upsurge of P.knowlesi malaria in South-East Asia has led clinicians to consider it as the fifth human malaria parasite. Recent studies in wild-living apes in Africa have revealed that P.falciparum, the most deadly form of human malaria, is not only human-host restricted as previously believed and its phylogenetic lineage is much more complex with new species identified in gorilla, bonobo and chimpanzee. Although less impressive, new data on biology of P.malariae, P.ovale and P.vivax are also emerging and will be briefly discussed in this review.
40
Anderson, Roger W., and Philip J. Youngman. "Complementation ofnpfmutations in diploid amoebae ofPhysarum polycephalum: the basis for a general method of complementation analysis at the amoebal stage." Genetical Research 45, no. 1 (February 1985): 21–35. http://dx.doi.org/10.1017/s0016672300021935.
Full textAbstract:
SummaryHaploid amoebae ofPhysarum polycephalummay form plasmodia by crossing, a sexual process that involves cellular and nuclear fusions, or by selfing, an asexual process in which the development of a single amoeba into a plasmodium may involve neither cellular nor nuclear fusion. Mutant strains (npf) in which selfing is suppressed were previously assigned to several functional groups on the basis of their ability to cross with one another in certain combinations. In the present study hybrid, diploid amoebae were isolated from both crossing-compatible and incompatible mixtures ofnpfmutants. The diploid amoebae from mixtures of compatible strains readily formed plasmodia by selfing, but selfing was suppressed in the diploids from incompatible mixtures. Thus the crossing tests betweennpfmutants may be viewed as complementation tests: their results reflect the differing selfing abilities of the hybrid, diploid amoebae that formed in each mixture. Genetical and environmental factors affecting the efficiency of formation of diploid amoebae were studied, and the diploids were shown to be stable during repeated subcultures. Although diploid amoebae carrying complementingnpfmutations readily formed plasmodia by selfing at 26 δC, they could be cultured without plasmodium formation at 30 δC, a temperature that also inhibited selfing of the haploidnpf+strains. Ways are discussed of exploiting this combination of properties in a general procedure for isolating and testing diploids for dominance and complementation of amoebal mutations inP. polycephalum.
41
Raja Yahya, Mohd Fakharul Zaman, and Hasidah Mohd Sidek. "Comparative Study on Mitogen Activated Protein Kinase of Plasmodium Species by Using in silico Method." Scientific Research Journal 9, no. 1 (June 1, 2012): 1. http://dx.doi.org/10.24191/srj.v9i1.9411.
Full textAbstract:
Malaria parasites, Plasmodium can infect a wide range of hosts including humans and rodents. There are two copies of mitogen activated protein kinases (MAPKs) in Plasmodium, namely MAPK1 and MAPK2. The MAPKs have been studied extensively in the human Plasmodium, P. falciparum. However, the MAPKs from other Plasmodium species have not been characterized and it is therefore the premise of presented study to characterize the MAPKs from other Plasmodium species-P. vivax, P. knowlesi, P. berghei, P. chabaudi and P.yoelli using a series of publicly available bioinformatic tools. In silico data indicates that all Plasmodium MAPKs are nuclear-localized and contain both a nuclear localization signal (NLS) and a Leucine-rich nuclear export signal (NES). The activation motifs of TDY and TSH were found to be fully conserved in Plasmodium MAPK1 and MAPK2, respectively. The detailed manual inspection of a multiple sequence alignment (MSA) construct revealed a total of 17 amino acid stack patterns comprising of different amino acids present in MAPKJ and MAPK2 respectively, with respect to rodent and human Plasmodia. It is proposed that these amino acid stack patterns may be useful in explaining the disparity between rodent and human Plasmodium MAPKs.
42
Narang, Prineha, Ravishankar Sundararaman, and Harry A. Atwater. "Plasmonic hot carrier dynamics in solid-state and chemical systems for energy conversion." Nanophotonics 5, no. 1 (June 1, 2016): 96–111. http://dx.doi.org/10.1515/nanoph-2016-0007.
Full textAbstract:
Abstract Surface plasmons provide a pathway to efficiently absorb and confine light in metallic nanostructures, thereby bridging photonics to the nano scale. The decay of surface plasmons generates energetic ‘hot’ carriers, which can drive chemical reactions or be injected into semiconductors for nano-scale photochemical or photovoltaic energy conversion. Novel plasmonic hot carrier devices and architectures continue to be demonstrated, but the complexity of the underlying processes make a complete microscopic understanding of all the mechanisms and design considerations for such devices extremely challenging.Here,we review the theoretical and computational efforts to understand and model plasmonic hot carrier devices.We split the problem into three steps: hot carrier generation, transport and collection, and review theoretical approaches with the appropriate level of detail for each step along with their predictions.We identify the key advances necessary to complete the microscopic mechanistic picture and facilitate the design of the next generation of devices and materials for plasmonic energy conversion.
43
Mouatcho, Joel C., and J. P. Dean Goldring. "Malaria rapid diagnostic tests: challenges and prospects." Journal of Medical Microbiology 62, no. 10 (October 1, 2013): 1491–505. http://dx.doi.org/10.1099/jmm.0.052506-0.
Full textAbstract:
In the last decade, there has been an upsurge of interest in developing malaria rapid diagnostic test (RDT) kits for the detection of Plasmodium species. Three antigens – Plasmodium falciparum histidine-rich protein 2 (PfHRP2), plasmodial aldolase and plasmodial lactate dehydrogenase (pLDH) – are currently used for RDTs. Tests targeting HRP2 contribute to more than 90 % of the malaria RDTs in current use. However, the specificities, sensitivities, numbers of false positives, numbers of false negatives and temperature tolerances of these tests vary considerably, illustrating the difficulties and challenges facing current RDTs. This paper describes recent developments in malaria RDTs, reviewing RDTs detecting PfHRP2, pLDH and plasmodial aldolase. The difficulties associated with RDTs, such as genetic variability in the Pfhrp2 gene and the persistence of antigens in the bloodstream following the elimination of parasites, are discussed. The prospect of overcoming the problems associated with current RDTs with a new generation of alternative malaria antigen targets is also described.
44
Babokh, Fatima, Soumia Nachat, Ibtissam Ait Boucetta, Youssra El Amrani, Fatimzahra Rahali, and Awatif El Hakkouni. "MIXED MALARIA INFECTION: ABOUT AN IMPORTED CASE AND REVIEW OF THE LITERATURE." International Journal of Advanced Research 10, no. 04 (April 30, 2022): 481–85. http://dx.doi.org/10.21474/ijar01/14571.
Full textAbstract:
Mixed malaria infections with Plasmodium are rare and can lead to more serious complications than a single infection. They are particularly common in travelers to malaria-endemic areas. Proper diagnosis and treatment of cases help to control this infection.We report the case of a rare and severe malaria infection, associating two plasmodial species: Plasmodium falciparum and P.vivax, with high parasitemia and fatal complication.
45
Kang, Lei, Joshua A. Robinson, and Douglas H. Werner. "Exploiting plasmons in 2D metals for refractive index sensing: Simulation study." Journal of Applied Physics 132, no. 22 (December 14, 2022): 223103. http://dx.doi.org/10.1063/5.0123648.
Full textAbstract:
Ultrathin and two-dimensional (2D) metals can support strong plasmons, with concomitant tight field confinement and large field enhancement. Accordingly, 2D-metal nanostructures exhibiting plasmonic resonances are highly sensitive to the environment and intrinsically suitable for optical sensing. Here, based on a proof-of-concept numerical study, nano-engineered ultrathin 2D-metal films that support infrared plasmons are demonstrated to enable highly responsive refractive index (RI) sensing. For 3 nm-Au nanoribbons exhibiting plasmonic resonances at wavelengths around 1600 nm, a RI sensitivity of SRI > 650 nm per refractive index unit (RIU) is observed for a 100 nm-thick analyte layer. A parametric study of the 2D-Au system indicates the strong dependence of the RI sensitivity on the 2D-metal thickness. Furthermore, for an analyte layer as thin as 1 nm, a RI sensitivity up to 110 (90 nm/RIU) is observed in atomically thin 2D-In (2D-Ga) nanoribbons exhibiting highly localized plasmonic resonances at mid-infrared wavelengths. Our results not only reveal the extraordinary sensing characteristics of 2D-metal systems but also provide insight into the development of 2D-metal-based plasmonic devices for enhanced IR detection.
46
Huang, Hung Ji, Jeffrey Chi-Sheng Wu, Hai-Pang Chiang, Yuan-Fong Chou Chau, Yung-Sheng Lin, Yen Han Wang, and Po-Jui Chen. "Review of Experimental Setups for Plasmonic Photocatalytic Reactions." Catalysts 10, no. 1 (December 31, 2019): 46. http://dx.doi.org/10.3390/catal10010046.
Full textAbstract:
Plasmonic photocatalytic reactions have been substantially developed. However, the mechanism underlying the enhancement of such reactions is confusing in relevant studies. The plasmonic enhancements of photocatalytic reactions are hard to identify by processing chemically or physically. This review discusses the noteworthy experimental setups or designs for reactors that process various energy transformation paths for enhancing plasmonic photocatalytic reactions. Specially designed experimental setups can help characterize near-field optical responses in inducing plasmons and transformation of light energy. Electrochemical measurements, dark-field imaging, spectral measurements, and matched coupling of wavevectors lead to further understanding of the mechanism underlying plasmonic enhancement. The discussions herein can provide valuable ideas for advanced future studies.
47
Ugai, M. "Virtual satellite observations of plasmoids generated by fast reconnection in the geomagnetic tail." Annales Geophysicae 29, no. 8 (August 23, 2011): 1411–22. http://dx.doi.org/10.5194/angeo-29-1411-2011.
Full textAbstract:
Abstract. The present paper studies fundamental features of plasmoid propagation by virtual satellite observations in the simulation box. The plasmoid domain is divided into the plasmoid reconnection region P, where magnetized plasmas with reconnected field lines, heated by dissipation mechanisms of fast reconnection, are accumulated, and the plasmoid core region C, where magnetized plasmas with sheared field lines, initially embedded in the current sheet, is adiabatically compressed. When the virtual satellite is located in a position through which the plasmoid core region passes, it detects distinct changes in quantities at the interface between the regions P and C, where the north-south field component Bz has the bipolar profile and the sheared field component By has the peak value. The observed magnetic field profile is, both quantitatively and qualitatively, in good agreement with the standard one detected by actual satellite observations, although when the satellite location is very close to the X neutral line, where reconnection occurs, the Bz field profile becomes dipolarization-like rather than bipolar. If the satellite detects only the plasmoid region P outside region C, the standard magnetic field profile becomes obscure even if notable plasmoid signatures, such as enhanced plasma temperature and plasma flow, are observed. Unlike the traditional flux rope model based on multiple reconnections, it is demonstrated that the standard magnetic field profile, observed for plasmoids propagating in the geomagnetic tail, is the direct outcome of the single fast reconnection evolution.
48
Rotheneder, Andrea, Gernot Fritsche, Lothar Heinisch, Ute Möllmann, Susanne Heggemann, Clara Larcher, and Günter Weiss. "Effects of Synthetic Siderophores on Proliferation of Plasmodium falciparum in Infected Human Erythrocytes." Antimicrobial Agents and Chemotherapy 46, no. 6 (June 2002): 2010–13. http://dx.doi.org/10.1128/aac.46.6.2010-2013.2002.
Full textAbstract:
ABSTRACT Because iron is essential for Plasmodium falciparum, we investigated the in vitro potential of various synthetic siderophores to kill P. falciparum in infected human erythrocytes. The substances with the most promising profile, i.e., low 50% lethal doses for plasmodia and minimum toxicity towards mammalian cells, were siderophores with an acylated monocatecholate or a triscatecholate as substituent.
49
Fontinha, Diana, Isabel Moules, and Miguel Prudêncio. "Repurposing Drugs to Fight Hepatic Malaria Parasites." Molecules 25, no. 15 (July 28, 2020): 3409. http://dx.doi.org/10.3390/molecules25153409.
Full textAbstract:
Malaria remains one of the most prevalent infectious diseases worldwide, primarily affecting some of the most vulnerable populations around the globe. Despite achievements in the treatment of this devastating disease, there is still an urgent need for the discovery of new drugs that tackle infection by Plasmodium parasites. However, de novo drug development is a costly and time-consuming process. An alternative strategy is to evaluate the anti-plasmodial activity of compounds that are already approved for other purposes, an approach known as drug repurposing. Here, we will review efforts to assess the anti-plasmodial activity of existing drugs, with an emphasis on the obligatory and clinically silent liver stage of infection. We will also review the current knowledge on the classes of compounds that might be therapeutically relevant against Plasmodium in the context of other communicable diseases that are prevalent in regions where malaria is endemic. Repositioning existing compounds may constitute a faster solution to the current gap of prophylactic and therapeutic drugs that act on Plasmodium parasites, overall contributing to the global effort of malaria eradication.
50
Khurgin, Jacob B. "Replacing noble metals with alternative materials in plasmonics and metamaterials: how good an idea?" Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 375, no. 2090 (March 28, 2017): 20160068. http://dx.doi.org/10.1098/rsta.2016.0068.
Full textAbstract:
Noble metals that currently dominate the fields of plasmonics and metamaterials suffer from large ohmic losses. Some of the new plasmonic materials, such as doped oxides and nitrides, have smaller material loss, and using them in place of metals carries the promise of reduced-loss plasmonic and metamaterial structures, with sharper resonances and higher field concentrations. This promise is put to a rigorous analytical test in this work, which reveals that having low material loss is not sufficient to have reduced modal loss in plasmonic structures. To reduce the modal loss, it is absolutely necessary for the plasma frequency to be significantly higher than the operational frequency. Using examples of nanoparticle plasmons and gap plasmons one comes to the conclusion that, even in the mid-infrared spectrum, metals continue to hold an advantage over alternative media when it comes to propagation distances and field enhancements. Of course, the new materials still have an application niche where high absorption loss is beneficial, e.g. in medicine and thermal photovoltaics. This article is part of the themed issue ‘New horizons for nanophotonics’.