Quiver theories, soliton spectra and Picard-Lefschetz transformations

Quiver theories arising on D3-branes at orbifold and del Pezzo singularities are studied using mirror symmetry. We show that the quivers for the orbifold theories are given by the soliton spectrum of massive 2d N=2 theory with weighted projective spaces as target. For the theories obtained from the del Pezzo singularities we show that the geometry of the mirror manifold gives quiver theories related to each other by Picard-Lefschetz transformations, a subset of which are simple Seiberg duals. We also address how one indeed derives Seiberg duality on the matter content from such geometrical transitions and how one could go beyond and obtain certain ``fractional Seiberg duals.'' Moreover, from the mirror geometry for the del Pezzos arise certain Diophantine equations which classify all quivers related by Picard-Lefschetz. Some of these Diophantine equations can also be obtained from the classification results of Cecotti-Vafa for the 2d N=2 theories.Comment: 34 pages, 11 figure

Interleukin-1 stimulates ovarian prostaglandin biosynthesis: Evidence for heterologous contact-independent cell-cell interaction

An increasing body of information now suggests the existence of complete intraovarian IL-1 system replete with ligands, receptor, and receptor antagonist. Since IL-1 is an established mediator of inflammation and since ovulation may constitute an inflammatory-like reaction, consideration may be given to the possibility that IL-1 may play an intermediary role in the ovulatory process. To further assess the above hypothesis, we have set out to determine whether IL-1 is capable of promoting ovarian prostaglandin biosynthesis, an established component of the ovulatory cascade. Cultured whole ovarian dispersates from immature (25 day old) rats constitutively elaborated major prostaglandin species (PGE2 > PGF2-alpha) in a cell density-dependent fashion. Treatment with IL-1 produced dose-dependent increments in prostaglandin (PGE2 > PGF2-alpha) accumulation as compared with untreated controls. Comparable cellular densities of untreated or IL-1-beta-treated whole ovarian dispersates elaborated substantially more PGE2 as compared with isolated granulosa or theca-interstitial cell preparations suggesting a requirement for cell-cell interaction. Indeed, cell contact-dependent reconstitution experiments involving isolated granulosa and theca-interstitial cells at a projected physiologic ratio of 4:1 revealed synergistic interactions in the elaboration of PGE2 under both basal and IL-1-beta-treated circumstances. Identical results were obtained for cell contact-independent heterologous (but not homologous) coculture experiments. Taken together, our present findings reveal optimal basal and IL-1-stimulated ovarian prostaglandin (PGE2 > PGF2-alpha) biosynthesis to require heterologous, contact-independent, presumably humorally-mediated, cell-cell interaction. These observations along with the demonstration of the gonadotropin-dependent preovulatory induction of ovarian IL-1-beta gene expression provide strong support for the view that IL-1 may be the centerpiece of an intraovarian regulatory loop concerned with the promotion of the preovulatory cascade

Recent sedimentology at the grounding zone of the Kamb Ice stream, West Antarctica and implications for ice shelf extent

Sediment accumulating beneath floating ice contains a record of ice dynamics in polar regions where in situ observations are rare. In 2019 a hole was melted through a 590m-thick region of the Ross Ice Shelf ∼5 km seawards of the Kamb Ice Stream (KIS) grounding line (82.7841°S, 155.2626°W) to access the seafloor. Imagery from a remotely operated vehicle (ROV, Icefin) shows ocean current-generated ripples likely formed by tidal flow parallel to the grounding line (GL). Observed current speeds 30 ka or 14C dead. By contrast, 210Pb-210 activity of >30 Bq Kg−1 indicates deposition within the last 120 years. The combination of features suggests rapid rainout deposition from melting of a sediment-laden basal debris layer as the GL retreated, followed by some reworking by ocean currents and little modern accumulation. Although Tertiary diatoms are abundant, unambiguously Late Quaternary forms are absent and we speculate on the implications for Ross Ice Shelf stabilit