Symplectic Structure of 2D Dilaton Gravity

We analyze the symplectic structure of two-dimensional dilaton gravity by evaluating the symplectic form on the space of classical solutions. The case when the spatial manifold is compact is studied in detail. When the matter is absent we find that the reduced phase space is a two-dimensional cotangent bundle and determine the Hilbert space of the quantum theory. In the non-compact case the symplectic form is not well defined due to an unresolved ambiguity in the choice of the boundary terms.Comment: 12 pgs, Imperial TP/92-93/37, La-Tex fil

Quadratic s-Form Field Actions with Semi-bounded Energy

We give in this paper a partial classification of the consistent quadratic gauge actions that can be written in terms of s-form fields. This provides a starting point to study the uniqueness of the Yang-Mills action as a deformation of Maxwell-like theories. We also show that it is impossible to write kinetic 1-form terms that can be consistently added to other 1-form actions such as tetrad gravity in four space-time dimensions even in the presence of a Minkowskian metric background.Comment: 1+35 papes in (DIN A4 format

Some new Menon designs with parameters (196,91,42)

There are exactly 54 symmetric (196,91,42) designs admitting an automorphism group isomorphic to $Frob_{13 cdot 6} times Z_3$ acting with orbit size distribution (1,13,13,13,39,39,39,39) for blocks and points. For 50 of these designs the full automorphism group has order 234 and is isomorphic to $Frob_{13 cdot 6} times Z_3$. The remaining four designs have $Frob_{13 cdot 6} times Frob_{7 cdot 3}$ as a full automorphism group.Among these designs there are 18 self-dual designs and 18 pairs of mutually dual ones. The derived designs (with respect to the fixed block) of the four designs with a full automorphism group of order 1638 are cyclic

Some Hadamard designs admitting a faithful action of Frobenius groups

We have constructed three new symmetric (71,35,17) designs having $Frob_{17 cdot 8}$ as an automorphism group. Also constructed are symmetric designs with parameters (43,21,10), (67,33,16) and (71,35,17) admitting an automorphism group isomorphic to $Frob_{43 cdot 7}$, $Frob_{67 cdot 11}$ and $Frob_{71 cdot 7}$, respectively, which turn out to be isomorphic to previously known designs, constructed via cyclic difference sets. Each constructed Hadamard design leads to a series of Hadamard designs

On path graphs of incidence graphs

For a given graph $G$ and a positive integer $k$ the $P_k$-path graph $P_k(G)$ has for vertices the set of paths of length $k$ in $G$. Two vertices are connected in $P_k(G)$ when the intersection of the corresponding paths forms a path of length $k-1$ in $G$, and their union forms either a cycle or a path of length $k+1$. Path graphs were proposed as a generalization of line graphs. In this article we investigate some properties of path graphs of bipartite graphs, especially path graphs of incidence graphs of configurations

Glycosylation of extracellular proteins during somatic embryogenesis in pumpkin (Cucurbita pepo L.)

Biljne stanice u suspenziji rastu i izlučuju proteine u hranidbenu podlogu i time utječu na daljnji rast i diferencijaciju stanica. Glikoproteini čine većinu izvanstaničnih proteina od kojih mnogi imaju strukturnu i/ili enzimatsku ulogu. Ranija istraţivanja pokazala su da se profil izlučenih proteina mijenja ovisno o promjenama vezanim uz indukciju somatske embriogeneze, a nepravilna glikozilacija može izazvati zastoj u razvitku embrija. Jedan od najbolje opisanih glikoproteina vezanih uz somatsku embriogenezu biljaka je endohitinaza EP3, karakteristična za rani stadij embriogeneze u mrkve i uročnjaka. Cilj istraživanja bio je usporediti status glikozilacije proteina izlučenih u staničnoj suspenziji dviju embriogenih linija bundeve induciranih pomoću 2,4-D ili na modificiranoj podlozi MS bez hormona koja sadrži 1 mM NH4Cl kao jedini izvor dušika. Uočeno je da je tijekom kultivacije embriogenog tkiva u podlozi s NH4Cl kao jedinim izvorom dušika dolazilo do značajnog zakiseljavanja podloge. Dodatkom 25 mM MES, vrijednost pH podloge je stabilizirana što je potaklo izlučivanje izvanstaničnih proteina. Prisustvo i promjene u aktivnosti specifičnih izvanstaničnih endohitinaza ovisile su o hranidbenoj podlozi i razvojnim promjenama tijekom somatske embriogeneze. Izvanstanični proteini razdvojeni su elekroforezom SDS-PAGE, preneseni na membranu i analizirani obradom membrane različitim lektinima (ConA, GNA, DSA, PNA). Rezultati rada pokazali su da postoji razlika u razini glikozilacije uzrokovane različitim sastavom i vrijednosti pH kultivacijske podloge.Plant cells cultivated in a suspension secrete proteins in the cultivation medium, thereby affecting the further growth and cell differentiation. Glycoproteins make up the majority of extracellular proteins, many of which have structural and/or enzymatic role. Previous research has shown that the profile of extracted protein is changed in relation to changes during somatic embryogenesis induction. Moreover, an abnormal glycosylation may cause delay in plant embryo development. One of the best described glycoprotein associated with somatic embryogenesis of plants is endochitinase EP3, characteristic for the early stage of embryogenesis in carrot and Arabidopsis. The objective of this work was to compare the glycosylation status of proteins extracted in cell suspension of two pumpkin embriogenic lines induced by 2,4-D or on a modified MS medium without hormones containing 1 mM NH4Cl as the sole source of nitrogen. It was noted that the cultivation medium with NH4Cl as the sole source of nitrogen undergo acidification. The addition of 25 mM MES stabilized pH of the culture medium, what enhanced the secretion of extracellular proteins. Presence of specific endochitinases and changes in their activity depended on the medium composition and developmental changes during somatic embryogenesis. Extracellular proteins were separated by SDS-PAGE electrophoresis, transferred to membrane and analyzed by processing membrane with different lectins (ConA, GNA, DSA, PNA). The results showed that there was a difference in the level of glycosylation caused by medium composition and pH

Symmetric (36,15,6) design having U(3,3) as an automorphism group

Up to isomorphism there are four symmetric (36,15,6) designs with automorphisms of order 7. Full automorphism group of one of them is the Chevalley group G(2,2) = U(3,3) : Z2 of order 12096. Unitary group U(3,3) acts transitively on that design

H Αλεξανδρινή Γραμματεία – πηγή των γνώσεών μας περί της Αδριατικής

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