Topological Open String Amplitudes On Orientifolds

We study topological open string amplitudes on orientifolds without fixed planes. We determine the contributions of the untwisted and twisted sectors as well as the BPS structure of the amplitudes. We illustrate our general results in various examples involving D-branes in toric orientifolds. We perform the computations by using both the topological vertex and unoriented localization. We also present an application of our results to the BPS structure of the coloured Kauffman polynomial of knots.Comment: 43 pages, 8 figure

Metastable Quivers in String Compactifications

We propose a scenario for dynamical supersymmetry breaking in string compactifications based on geometric engineering of quiver gauge theories. In particular we show that the runaway behavior of fractional branes at del Pezzo singularities can be stabilized by a flux superpotential in compact models. Our construction relies on homological mirror symmetry for orientifolds.Comment: 22 pages, 1 figure; v2: references adde

Counting Higher Genus Curves with Crosscaps in Calabi-Yau Orientifolds

We compute all loop topological string amplitudes on orientifolds of local Calabi-Yau manifolds, by using geometric transitions involving SO/Sp Chern-Simons theory, localization on the moduli space of holomorphic maps with involution, and the topological vertex. In particular we count Klein bottles and projective planes with any number of handles in some Calabi-Yau orientifolds.Comment: 40 pages, 18 figures, some corrections in section

International, cooperative research in the Apuseni Mountains of western Romania

In May of 2006, nine American scientists and cavers from the Karst Research Group at the University of South Florida traveled to western Romania to attend and present at an international conference on records of climate change in caves in the historic Roman town of Baile Hurculane. The conference, co-sponsored by the “Emil Racoviţă” Speleological Institute of Romania and the Karst Waters Institute, drew more than 100 experts in the field of climate change and karst, and was a wonderful time spent alongside the thermal springs and Austro-Hungarian bathhouses nestled within the massive limestone canyon of the Cerna River. Following the conference and post-conference field trips in early June of 2006, six members of the American team joined with several Romanian colleagues to conduct paleoclimate research in the caves of the Apuseni Mountains of Transylvania. A follow-up trip in July of 2007 by a smaller research team completed the projects started the previous year. The NSS provided partial funding for the work in both 2006 and 2007 though an International Participation Grant. The Romanian Science Foundation and the Romanian Ministry of Education and Research provided much of the remaining funds

The Dental Technology in Art Foundry

The paper presents results of a study undertaken to implement the dental casting technique of small parts characterized by extremely complex drawings of surfaces and thicknesses reduced specific objects. During the study there was a similarity between this technique and casting forms obtained with models used to obtain spare fuses in the car industry. They could highlight differences between the materials and the equipment used in dental technology and art foundries

Trypanosoma brucei: β2-selective proteasome inhibitors do not block the proteasomal trypsin-like activity but are trypanocidal

Previous studies indicated that the proteasome of the protozoan parasite Trypanosoma brucei is particularly sensitive to inhibition of the trypsin-like activity. In this study, three newly developed β2 subunit-specific inhibitor (LU-102, LU-002c and LU-002i) were tested for their ability to block the trypsin-like activity of the trypanosomal proteasome. At 10 µM, none of the compounds affected the proteasomal trypsin-like activity in cell lysates of bloodstream forms of T. brucei. On the other hand, leupeptin, a well-established β2 inhibitor, supressed the proteasomal trypsin-like activity within trypanosome cell lysates with a 50% inhibitory concentration of 2 µM demonstrating the inhibitability of the trypsin-like activity of the T. brucei proteasome under the experimental condition. Nevertheless, two compounds (LU-102 and LU-002i) displayed moderate trypanocidal activity with 50% growth inhibition values of 6.9 and 8.5 µM, respectively. In the case of LU-102, it was shown that the trypanocidal activity of the compound was due to inhibition of the major lysosomal cysteine protease TbCATL. The main finding of this study indicate substantial inhibitor sensitivity differences between the trypsin-like sites of the human and trypanosomal proteasomes. Whether these differences can be exploited for the design of anti-trypanosomal drug therapies remains to be shown