Enhancing retinal images by nonlinear registration

Being able to image the human retina in high resolution opens a new era in many important fields, such as pharmacological research for retinal diseases, researches in human cognition, nervous system, metabolism and blood stream, to name a few. In this paper, we propose to share the knowledge acquired in the fields of optics and imaging in solar astrophysics in order to improve the retinal imaging at very high spatial resolution in the perspective to perform a medical diagnosis. The main purpose would be to assist health care practitioners by enhancing retinal images and detect abnormal features. We apply a nonlinear registration method using local correlation tracking to increase the field of view and follow structure evolutions using correlation techniques borrowed from solar astronomy technique expertise. Another purpose is to define the tracer of movements after analyzing local correlations to follow the proper motions of an image from one moment to another, such as changes in optical flows that would be of high interest in a medical diagnosis.Comment: 21 pages, 7 figures, submitted to Optics Communication

Formalismo Tcheco-Russo

The present work is dedicated to the discussion of the influence of Russian formalism over the Prague Linguistic Circle and the Czech structuralism as a whole. For that, the author presents the reader with different points of view, including from the Czech scholars themselves. The conclusion reached by the author is that structuralism is not a continuation or an evolution of the formalism, but a trend in itself that opposes its predecessor.O presente trabalho é dedicado à discussão da influência do formalismo russo sobre o Círculo Lingüístico de Praga e o estruturalismo tcheco como um todo. Para tanto, o autor apresenta ao leitor diversos pontos de vista, inclusive dos próprios estudiosos tchecos. A conclusão a que chega o autor é que o estruturalismo não é uma continuação ou uma evolução do formalismo, mas uma tendência em si mesma que se opõe a seu antecessor

Problems with the prospective connected autonomous vehicles regulation : Finding a fair balance versus the instinct for self-preservation

There would seem to be a potential regulatory problem with the crash algorithms for connected and autonomous vehicles that (normally) "kick in" should a crash be inevitable. Although the general regulatory considerations which have been put forward tend to seek a "fair balance" that would protect various users of the roads, a configuration which shielded other parties at the cost of the car user could be seen as posing an existential threat to the user by encroaching on his or her right to self-preservation. "Hacking the system" (i.e. modifying the configuration in order to obtain a more favourable outcome for the user) could therefore be understood as acting on one's instinct for self-preservation and - though illegal - could in certain situations turn out to be an action that is not punishable in law. The present article argues that in certain real post-crash situations, a person who has modified the code for his or her own benefit could be exonerated on the basis of existing legal provisions and thus go unpunished. This could create unforeseen flaws in the connected autonomous vehicles regulatory system.Peer reviewe

A functional study of AUXILIN-LIKE1 and 2, two putative clathrin uncoating factors in Arabidopsis

Clathrin-mediated endocytosis (CME) is a cellular trafficking process in which cargoes and lipids are internalized from the plasma membrane into vesicles coated with clathrin and adaptor proteins. CME is essential for many developmental and physiological processes in plants, but its underlying mechanism is not well characterized compared with that in yeast and animal systems. Here, we searched for new factors involved in CME in Arabidopsis thaliana by performing tandem affinity purification of proteins that interact with clathrin light chain, a principal component of the clathrin coat. Among the confirmed interactors, we found two putative homologs of the clathrin-coat uncoating factor auxilin previously described in non-plant systems. Overexpression of AUXILIN-LIKE1 and AUXILIN-LIKE2 in Arabidopsis caused an arrest of seedling growth and development. This was concomitant with inhibited endocytosis due to blocking of clathrin recruitment after the initial step of adaptor protein binding to the plasma membrane. By contrast, auxilin-like1/2 loss-of-function lines did not present endocytosis-related developmental or cellular phenotypes under normal growth conditions. This work contributes to the ongoing characterization of the endocytotic machinery in plants and provides a robust tool for conditionally and specifically interfering with CME in Arabidopsis

Specifita vybraných podjednotek exocystu při vývoji trichomu

Trichomy jsou jemné struktury epidermálního původu, které pokrývají povrch nadzemních orgánů většiny rostlin. Jednobuněčné trichomy Arabidopsis thaliana jsou dobře zavedeným modelem v buněčné a vývojové biologii rostlin, přesto je o procesech ukládání buněčné stěny během finální fáze zrání trichomu známo jen velmi málo. V naší laboratoři byla nedávno objevena role podjednotky poutacího komplexu exocyst EXO70H4 při zrání trichomu. V této práci byly za použití analýzy obrazu, histochemického barvení a FT-IR spektroskopie studovány defekty v buněčné stěně u ztrátového mutanta exo70H4. Bylo zjištěno, že mutace vede ke změně v ukládání pektinu a možná též ligninu a hemicelulóz. Byly připraveny transgenní linie s paralogy EXO70 exprimovanými pod promotorem EXO70H4 a jejich analýza ukázala, že nejbližší paralog EXO70H3 dokáže komplementovat mutaci EXO70H4, na rozdíl od paralogů EXO70A1 a EXO70B1. Na základě těchto výsledků jsou diskutovány otázky týkající se složení buněčné stěny trichomů, role EXO70H4 ve zrání trichomu a funkcí komplexu exocyst u rostlin. Klíčová slova: Arabidopsis, trichom, buněčná stěna, sekreční dráha, komplex exocyst, EXO70H4, FT-IR spektroskopieTrichomes are fine epidermal outgrowths covering aerial organs of most land plants. Although unicellular trichomes of Arabidopsis thaliana have long been used as a model system in plant cell and developmental biology, surprisingly little is known about the processes involved in cell wall biogenesis during the last stage of trichome maturation. A role of EXO70H4, a putative subunit of the vesicle tethering complex exocyst, in trichome maturation has recently been identified in our laboratory. Image analysis, histochemical detection and FT-IR spectroscopy methods were used in this study to analyze cell wall defects of the exo70H4 LOF mutant, revealing the mutation causes altered deposition of pectins and possibly also lignins and hemicelluloses. Transgenic lines with EXO70 paralogues driven by the EXO70H4 promoter were prepared and their analysis revealed that the closest paralogue EXO70H3, unlike EXO70A1 and EXO70B1, can complement the exo70H4 mutation. Based on the results, questions concerning trichome cell wall composition, the role of EXO70H4 in trichome maturation and functions of the plant exocyst complex are discussed. Keywords: Arabidopsis, trichome, cell wall, secretory pathway, exocyst complex, EXO70H4, FT-IR spectroscopyKatedra experimentální biologie rostlinDepartment of Experimental Plant BiologyPřírodovědecká fakultaFaculty of Scienc

„Křičel jsem: – Mrdat, mrdat!“ Vítězslav Nezval a jeho poetika Moskvy

In August 1934, poet and writer Vítězslav Nezval (1900-1958), a leading personality of the czechoslovak inter-war art avant-garde and also a member of the communist party, visited Moscow as one of the western guests invited to the founding congress of the Union of Soviet Writers; one year later, he published a prosaic-essayistic reflection of his visit under the title The Invisible Moscow (Neviditelná Moskva. Praha: F. Borový, 1935). The purpose of the present study approached from a semiotic angle is to obtain access to the intentional meaning of this specific testimony concealed behind a factual description of events and environments. The author first outlines a broader socio-political context consisting in an intensive interest of Western left-wing intellectuals in the Soviet Union between the world wars and, on the other hand., in systematic efforts of the Soviet leadership to make use of this potential for their own benefit. Nezval ranked among artists who felt a priori sympathies toward the Soviet social experiment, and they are clearly seen in his text, although he himself declared, that his intention was not to provide q testimony about the Soviet "objective reality',, which is what media reports or articles do. To understand Nezval's work, the author believes it must be kept in mind that Nezvol, while in the Soviet Union, was looking for, first and foremost, inspiration and connections with poetic and ideological principles he professed. Nezval's cognitive method is intuition, free of any rationaI and critical reflections, and his creative principle is imagination, whose incarnation Nezval found in surrealism. The reality around him serves as a matter for a distillation of experiences occurring in a dream mode. This allows him to overlook or willfully interpret various phenomena related, for example, to the repressive aspect of Stalin's regime or the onerous everydayness of the Soviet Union's citizens. The author sees the dominant feature of this dreamlike experience and the line connecting seemingly compatible segments of reality into all-embracing lyrical intoxication in an eroticprinciple. Nezval is excited by Moscow as an object of bliss, as a source of sexual arousal. This principle is offered to him as a key enabling an individual to cross the boundary of individualism and blend into the society as a bridge between the eternity of sexual ecstasy and the eternity of the classless Communist society, thus promising the fulfillment of human utopias. The author provides on analysis of the text of The Invisible Moscow ln supporf of his conclusions, and links them to some period esthetic and philosophical concepts