162 research outputs found

    Reflection of a Lieb-Liniger wave packet from the hard-wall potential

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    Nonequilibrium dynamics of a Lieb-Liniger system in the presence of the hard-wall potential is studied. We demonstrate that a time-dependent wave function, which describes quantum dynamics of a Lieb-Liniger wave packet comprised of N particles, can be found by solving an NN-dimensional Fourier transform; this follows from the symmetry properties of the many-body eigenstates in the presence of the hard-wall potential. The presented formalism is employed to numerically calculate reflection of a few-body wave packet from the hard wall for various interaction strengths and incident momenta.Comment: revised version, improved notation, Fig. 5 adde

    Nonlinear optics and light localization in periodic photonic lattices

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    We review the recent developments in the field of photonic lattices emphasizing their unique properties for controlling linear and nonlinear propagation of light. We draw some important links between optical lattices and photonic crystals pointing towards practical applications in optical communications and computing, beam shaping, and bio-sensing.Comment: to appear in Journal of Nonlinear Optical Physics & Materials (JNOPM

    Response of GaN to energetic ion irradiation: conditions for ion track formation

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    We investigated the response of wurzite GaN thin films to energetic ion irradiation. Both swift heavy ions (92 MeV Xe23+, 23 MeV I6+) and highly charged ions (100 keV Xe40+) were used. After irradiation, the samples were investigated using atomic force microscopy, grazing incidence small angle X-ray scattering, Rutherford backscattering spectroscopy in channelling orientation and time of flight elastic recoil detection analysis. Only grazing incidence swift heavy ion irradiation induced changes on the surface of the GaN, when the appearance of nanoholes is accompanied by a notable loss of nitrogen. The results are discussed in the framework of the thermal spike model

    Synthesis and characterization of silicon nitride whiskers

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    Silicon nitride whiskers were synthesized by the carbothermal reduction of silica under nitrogen gas flow. The formation of silicon nitride whiskers occurs through a gas-phase reaction, 3SiO(g)+3CO(g)+2N 2 (g)=Si 3 N 4 ( β )+3CO 2 (g), and the VS mechanism. The generation of SiO gas was enhanced by the application of a halide bath. Various nitrogen flow rates resulted in different whisker yields and morphologies. A suitable gas composition range of N 2 , SiO and O 2 is necessary to make silicon nitride stable and grow in a whisker form. The oxygen partial pressure of the gas phase was measured by an oxygen sensor and the gas phase was analysed for CO/CO 2 by gas chromatography. Silicon nitride was first formed as a granule, typically a polycrystalline, and then grown as a single crystal whisker from the {1 0 0} plane of the granule along the 〈 210 〉 direction. The whiskers were identified as β ′-sialon with Z value ranging from 0.8 to 1.1, determined by lattice parameter measurements.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44697/1/10853_2004_Article_BF01045372.pd

    Cardiac Glycosides Ouabain and Digoxin Interfere with the Regulation of Glutamate Transporter GLAST in Astrocytes Cultured from Neonatal Rat Brain

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    Glutamate transport (GluT) in brain is mediated chiefly by two transporters GLT and GLAST, both driven by ionic gradients generated by (Na+, K+)-dependent ATPase (Na+/K+-ATPase). GLAST is located in astrocytes and its function is regulated by translocations from cytoplasm to plasma membrane in the presence of GluT substrates. The phenomenon is blocked by a naturally occurring toxin rottlerin. We have recently suggested that rottlerin acts by inhibiting Na+/K+-ATPase. We now report that Na+/K+-ATPase inhibitors digoxin and ouabain also blocked the redistribution of GLAST in cultured astrocytes, however, neither of the compounds caused detectable inhibition of ATPase activity in cell-free astrocyte homogenates (rottlerin inhibited app. 80% of Pi production from ATP in the astrocyte homogenates, IC50 = 25 μM). Therefore, while we may not have established a direct link between GLAST regulation and Na+/K+-ATPase activity we have shown that both ouabain and digoxin can interfere with GluT transport and therefore should be considered potentially neurotoxic

    Molecular evolution of the LNX gene family

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    <p>Abstract</p> <p>Background</p> <p>LNX (Ligand of Numb Protein-X) proteins typically contain an amino-terminal RING domain adjacent to either two or four PDZ domains - a domain architecture that is unique to the LNX family. LNX proteins function as E3 ubiquitin ligases and their domain organisation suggests that their ubiquitin ligase activity may be targeted to specific substrates or subcellular locations by PDZ domain-mediated interactions. Indeed, numerous interaction partners for LNX proteins have been identified, but the <it>in vivo </it>functions of most family members remain largely unclear.</p> <p>Results</p> <p>To gain insights into their function we examined the phylogenetic origins and evolution of the <it>LNX </it>gene family. We find that a <it>LNX1/LNX2</it>-like gene arose in an early metazoan lineage by gene duplication and fusion events that combined a RING domain with four PDZ domains. These PDZ domains are closely related to the four carboxy-terminal domains from multiple PDZ domain containing protein-1 (MUPP1). Duplication of the <it>LNX1/LNX2</it>-like gene and subsequent loss of PDZ domains appears to have generated a gene encoding a LNX3/LNX4-like protein, with just two PDZ domains. This protein has novel carboxy-terminal sequences that include a potential modular LNX3 homology domain. The two ancestral <it>LNX </it>genes are present in some, but not all, invertebrate lineages. They were, however, maintained in the vertebrate lineage, with further duplication events giving rise to five LNX family members in most mammals. In addition, we identify novel interactions of LNX1 and LNX2 with three known MUPP1 ligands using yeast two-hybrid asssays. This demonstrates conservation of binding specificity between LNX and MUPP1 PDZ domains.</p> <p>Conclusions</p> <p>The <it>LNX </it>gene family has an early metazoan origin with a LNX1/LNX2-like protein likely giving rise to a LNX3/LNX4-like protein through the loss of PDZ domains. The absence of LNX orthologs in some lineages indicates that LNX proteins are not essential in invertebrates. In contrast, the maintenance of both ancestral <it>LNX </it>genes in the vertebrate lineage suggests the acquisition of essential vertebrate specific functions. The revelation that the LNX PDZ domains are phylogenetically related to domains in MUPP1, and have common binding specificities, suggests that LNX and MUPP1 may have similarities in their cellular functions.</p

    Navika tjelesne aktivnosti kod autora koji su objavljivali u Hrvatskom časopisu za javno zdravstvo

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    Navike se mogu definirati kao stečeni oblik ponašanja. Navike nastaju višestrukim, višegodišnjim, ponavljanjem odgovarajućih pokreta ili radnji. Postoje razne vrste navika npr. navike ponašanja, higijenske navike, radne navike itd. Neke od njih su pozitivne, a neke negativne. Tjelesna aktivnost je primjer pozitivne navike, koja pridonosi poboljšanju psiho-fizičkog stanja čovjeka, te je stog vrlo važna u primarnoj prevenciji niza kroničnih i akutnih bolesti. Da bi se stvorila navika redovitog tjelesnog vježbanja potrebno je, unatoč fizičkom zamoru koji proizlazi iz same aktivnosti, ponavljati odgovarajuće vježbe ili aktivnosti iz dana u dan, iz godine u godinu. Kada organizam počne prepoznavati umor u vrijeme treninga, a pogotovo nakon treninga, kao vrhunac ugode, tada možete biti sigurni da ste ovisnik o jednoj pozitivnoj navici- tjelesnoj aktivnosti.

    Research misconduct in the fields of ethics and philosophy: researchers’ perceptions in Spain

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    This is the Author’s Original Manuscript (AOM) (also called a “preprint”) sent to review to Science and Engineering Ethics on 11/10/2020. The final version of the article was published online at SEE on 21/01/2021. The online version is available at: https://doi.org/10.1007/s11948-021-00278-wEmpirical studies have revealed a disturbing prevalence of research misconduct in a wide variety of disciplines, although not, to date, in the areas of ethics and philosophy. This study aims to provide empirical evidence on perceptions of how serious a problem research misconduct is in these two disciplines in Spain, particularly regarding the effects that the model used to evaluate academics’ research performance may have on their ethical behaviour. The methodological triangulation applied in the study combines a questionnaire, a debate at the annual meeting of scientific association, and in-depth interviews. Of the 541 questionnaires sent out, 201 responses were obtained (37.1% of the total sample), with a significant difference in the participation of researchers in philosophy (30.5%) and in ethics (52.8%); 26 researchers took part in the debate and 14 interviews were conducted. The questionnaire results reveal that 91.5% of the respondents considered research misconduct to be on the rise; 63.2% considered at least three of the fraudulent practices referred to in the study to be commonplace, and 84.1% identified two or more such practices. The researchers perceived a high prevalence of duplicate publication (66.5%) and self-plagiarism (59.0%), use of personal influence (57.5%) and citation manipulation (44.0%), in contrast to a low perceived incidence of data falsification or fabrication (10.0%). The debate and the interviews corroborated these data. Researchers associated the spread of these misconducts with the research evaluation model applied in Spain
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