738 research outputs found
GigaGauss solenoidal magnetic field inside of bubbles excited in under-dense plasma
Magnetic fields have a crucial role in physics at all scales, from
astrophysics to nanoscale phenomena. Large fields, constant or pulsed, allow
investigation of material in extreme conditions, opening up plethora of
practical applications based on ultra-fast process, and studying phenomena
existing only in exotic astro-objects like neutron stars or pulsars. Magnetic
fields are indispensable in particle accelerators, for guiding the relativistic
particles along a curved trajectory and for making them radiate in synchrotron
light sources and in free electron lasers. In the presented paper we propose a
novel and effective method for generating solenoidal quasi-static magnetic
field on the GigaGauss level and beyond, in under-dense plasma, using
screw-shaped high intensity laser pulses. In comparison with already known
techniques which typically rely on interaction with over-dense or solid
targets, where radial or toroidal magnetic field localized at the stationary
target were generated, our method allows to produce gigantic solenoidal fields,
which is co-moving with the driving laser pulse and collinear with accelerated
electrons. The solenoidal field is quasi-stationary in the reference frame of
the laser pulse and can be used for guiding electron beams and providing
synchrotron radiation beam emittance cooling for laser-plasma accelerated
electron and positron beams, opening up novel opportunities for designs of the
light sources, free electron lasers, and high energy colliders based on laser
plasma acceleration.Comment: 15 pages, 9 figures. Main text (without abstract, References and
Appendix): 12 page
A ferritin szerepe a szőlő stressztűrő képességének fokozásában = The role of ferritin in enhancing the stress tolerance of grapevine
EmbriogĂ©n kalluszt állĂtottuk elĹ‘ Richter110 (alany) Ă©s Chardonnay (nemes) szĹ‘lĹ‘ fajták portokajibĂłl. Ezeket Medicago sativa ferritint (MsFerr) tartalmazĂł Agrobacterium vektorokkal transzformáltunk. A DNS beĂ©pĂĽlĂ©sĂ©t genomikus PCR-rel ellenĹ‘riztĂĽk. Poliklonális ellenanyagot állĂtottunk elĹ‘, mellyel megállapĂtottuk, hogy a transzláciĂł magas szintű volt, a transzkriptumbĂłl nagy mennyisĂ©gű, megfelelĹ‘en processzált fehĂ©rjetermĂ©k keletkezett. A transzgenikus szĹ‘lĹ‘ növĂ©nyek elkĂ©szĂĽltĂ©ig dohányban teszteltĂĽk az MsFerr gĂ©nt tartalmazĂł konstrukciĂłkat. A teljes növĂ©nyeken vĂ©gzett UV-B kezelĂ©s, ill. levĂ©lkorongok közvetlen oxidatĂv stresszre adott válaszai alapján megállapĂtottuk, hogy az MsFerr növĂ©nyek toleránsabbak voltak, mint a nem expresszálĂł kontrollok. Az MsFerr Richter 110 növĂ©nyek regenerálása, szelekciĂłja Ă©s felszaporĂtása sikeres volt, az MsFerr Chardonnay növĂ©nyek felszaporĂtása azonban hajtásnövekedĂ©si problĂ©mák miatt nem sikerĂĽlt. Három MsFerr Richter 110 vonalat vizsgáltunk. GyökĂ©r stresszkĂ©nt fás szárĂş dugványok tápoldatához hidrogĂ©nkarbonátot adtunk, ami klorotikus Ă©s levĂ©l száradási tĂĽnetek okozott Ebben nem kaptunk lĂ©nyeges kĂĽlönbsĂ©get a transzgenikus Ă©s transzformálatlan növĂ©nyek között. Ezzel szemben, a leveleket Ă©rĹ‘ hatásokkal: paraquat, NaCl sĂł-stressz Ă©s tBHP indukált lipid peroxidáciĂłval szemben az MsFerr expresszálĂł vonalak toleránsabbak voltak (kisebb stressz-indukált fotoszintĂ©zis csökkenĂ©st mutattak) mint a transzformálatlanok. | Embryogenic calli were started from anthers of Richter 110 (rootstock) and Chardonnay (scion) grapevine and transformed with Agrobacterium harbouring Medicago sativa ferritin gene (MsFerr). Genomic PCR and protein immunoblotting using a polyclonal antibody confirmed that the transcription and processing of MsFerr was successful. Regeneration, selection and propagation of MsFerr Richter 110 plants was successful, but transformed MsFerr Chardonnay plants did not grow sufficiently. Until transgenic grapevine plants became available, preliminary experiments were carried out with MsFerr expressing tobacco. UV-B irradiation of whole plants as well as treatments of leaf disks with various chemical elicitors showed that MsFerr plants were more stress tolerant than non-expressing controls. After regeneration and propagation, three transgenic MsFerr Richter 110 lines were tested. Roots of green cuttings were stressed by flooding and in this experiment transgenic plants did not show significantly higher tolerance to hypoxia/bicarbonate than non-transferred ones. Leaves, however, showed increased tolerance to paraquat, salt stress and tBHP induced lipid peroxidation: their photosynthesis was less affected by these stressors than those from non-transformed plants
Quadratic operators used in deducing exact ground states for correlated systems: ferromagnetism at half filling provided by a dispersive band
Quadratic operators are used in transforming the model Hamiltonian (H) of one
correlated and dispersive band in an unique positive semidefinite form coopting
both the kinetic and interacting part of H. The expression is used in deducing
exact ground states which are minimum energy eigenstates only of the full
Hamiltonian. It is shown in this frame that at half filling, also dispersive
bands can provide ferromagnetism in exact terms by correlation effects .Comment: 7 page
Statinok és az emésztőrendszeri daganatok
The antitumour effect of statins has already been proven in animal experiments and human cancer cell lines in several gastrointestinal cancers. The chemopreventive mechanism is not completely clarified but the enhancement of oxidative stress, increased autophagy, altered expression of pro- and antiproliferative proteins and their influence on intracellular signaling pathways may play a role. Randomized studies, however, failed to confirme the expected results obtained from experimental studies. The goal of this review is to summarize the data available in the literature regarding the chemopreventive effects of statins on several gastrointestinal cancers. Results of clinical trials suggest that 10-20 mg statin daily has no or minimal antitumour effect. Chemopreventive effect of hydrophilic statins could not be detected but it seems to be significant in the case of hydrophobic statins. There are only few data available on the long-term daily use of 30-40 mg statins. Further long-term evaluation of the effect of statins regarding gastrointestinal cancers is needed, and an analysis of compound- and dose-related subgroups would be beneficial. Chemoprevention with statins cannot yet be accepted as standard medical practice. Use of statins as chemopreventive agents cannot be a substitute for regular oncological screening or surveillance. Orv. Hetil., 2014, 155(18), 687-693
GigaGauss solenoidal magnetic field inside bubbles excited in under-dense plasma
This paper proposes a novel and effective method for generating GigaGauss level, solenoidal quasi-static magnetic fields in under-dense plasma using screw-shaped high intensity laser pulses. This method produces large solenoidal fields that move with the driving laser pulse and are collinear with the accelerated electrons. This is in contrast with already known techniques which rely on interactions with over-dense or solid targets and generates radial or toroidal magnetic field localized at the stationary target. The solenoidal field is quasi-stationary in the reference frame of the laser pulse and can be used for guiding electron beams. It can also provide synchrotron radiation beam emittance cooling for laser-plasma accelerated electron and positron beams, opening up novel opportunities for designs of the light sources, free electron lasers, and high energy colliders based on laser plasma acceleration
A nonperturbative study of phase transitions in the multi-frequency sine-Gordon model
The phase spaces of the two- and three-frequency sine-Gordon models are
examined in the framework of truncated conformal space approach. The focus is
mainly on a tricritical point in the phase space of the three-frequency model.
We give substantial evidence that this point exists. We also find the critical
line in the phase space and present TCSA data showing the change of the
spectrum on the critical line as the tricritical endpoint is approached. We
find a few points of the line of first order transition as well.Comment: 26 pages, LaTeX, minor modificatio
Disordered proteins and network disorder in network descriptions of protein structure, dynamics and function. Hypotheses and a comprehensive review
During the last decade, network approaches became a powerful tool to describe protein structure and dynamics. Here we review the links between disordered proteins and the associated networks, and describe the consequences of local, mesoscopic and global network disorder on changes in protein structure and dynamics. We introduce a new classification of protein networks into ‘cumulus-type’, i.e., those similar to puffy (white) clouds, and ‘stratus-type’, i.e., those similar to flat, dense (dark) low-lying clouds, and relate these network types to protein disorder dynamics and to differences in energy transmission processes. In the first class, there is limited overlap between the modules, which implies higher rigidity of the individual units; there the conformational changes can be described by an ‘energy transfer’ mechanism. In the second class, the topology presents a compact structure with significant overlap between the modules; there the conformational changes can be described by ‘multi-trajectories’; that is, multiple highly populated pathways. We further propose that disordered protein regions evolved to help other protein segments reach ‘rarely visited’ but functionally-related states. We also show the role of disorder in ‘spatial games’ of amino acids; highlight the effects of intrinsically disordered proteins (IDPs) on cellular networks and list some possible studies linking protein disorder and protein structure networks
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