Black-holes, topological strings and large N phase transitions

The counting of microstates of BPS black-holes on local Calabi-Yau of the form ${\mathcal O}(p-2)\oplus{\mathcal O}(-p) \longrightarrow S^2$ is explored by computing the partition function of q-deformed Yang-Mills theory on $S^2$. We obtain, at finite $N$, the instanton expansion of the gauge theory. It can be written exactly as the partition function for U(N) Chern-Simons gauge theory on a Lens space, summed over all non-trivial vacua, plus a tower of non-perturbative instanton contributions. In the large $N$ limit we find a peculiar phase structure in the model. At weak string coupling the theory reduces to the trivial sector and the topological string partition function on the resolved conifold is reproduced in this regime. At a certain critical point, instantons are enhanced and the theory undergoes a phase transition into a strong coupling regime. The transition from the strong coupling phase to the weak coupling phase is of third order.Comment: 16 pages, 3 figures; Invited talk given at QG05, Cala Gonone (Italy), September 200

On the corrections of ERA-40 surface flux products consistent with the Mediterranean heat and water budgets and the connection between basin surface total heat flux and NAO

This is a study of heat fluxes and heat budget of the Mediterranean Sea using the European Centre for Medium-Range Weather Forecasts (ECMWF) 45 year reanalysis data set ERA-40. The simple use of the ERA-40 surface flux components fails to close the budget and, in particular, the shortwave radiation flux is found to be underestimated with respect to observed data by about 10%. The heat flux terms are recomputed and corrected in order to close the heat and freshwater budgets of the Mediterranean basin over the period 1958 to 2001, thus producing a corrected ERA-40 surface flux data set. Various satellite and in situ observational data are used to construct spatially varying corrections to the ERA-40 products needed to compute the air-sea fluxes. The corrected interannual and climatological net surface heat and freshwater fluxes are and , respectively, which are regarded as satisfactorily closing the Mediterranean heat and water budgets. It is also argued that there is an important contribution from large heat losses associated with a few severe winters over the Mediterranean Sea. This is shown to be related to wind regime anomalies, which strongly affect the latent heat of evaporation that is the main responsible for the interannual modulation of the total heat flux. Furthermore, the surface total heat flux anomaly time series is compared with the North Atlantic Oscillation (NAO) index, and the result is a positive correlation with ocean warming for positive NAO index and cooling associated to negative index periods

Insulin-like growth factor binding protein-5 as a biomarker for detection of early liver disease

Study identifying an Insulin-like growth factor binding protein-5 as a biomarker for detection of early liver disease presented at the annual congress of the british toxicology societ

Obligatory role for phosphatidylinositol 4,5-bisphosphate in activation of native TRPC1 store-operated channels in vascular myocytes

In the present study the effect of phosphatidylinositol 4,5-bisphosphate (PIP2) was studied on a native TRPC1 store-operated channel (SOC) in freshly dispersed rabbit portal vein myocytes. Application of diC8-PIP2, a water soluble form of PIP2, to quiescent inside-out patches evoked single channel currents with a unitary conductance of 1.9 pS. DiC8-PIP2-evoked channel currents were inhibited by anti-TRPC1 antibodies and these characteristics are identical to SOCs evoked by cyclopiazonic acid (CPA) and BAPTA-AM. SOCs stimulated by CPA, BAPTA-AM and the phorbol ester phorbol 12,13-dibutyrate (PDBu) were reduced by anti-PIP2 antibodies and by depletion of tissue PIP2 levels by pre-treatment of preparations with wortmannin and LY294002. However, these reagents did not alter the ability of PIP2 to activate SOCs in inside-out patches. Co-immunoprecipitation techniques demonstrated association between TRPC1 and PIP2 at rest, which was greatly decreased by wortmannin and LY294002. Pre-treatment of cells with PDBu, which activates protein kinase C (PKC), augmented SOC activation by PIP2 whereas the PKC inhibitor chelerythrine decreased SOC stimulation by PIP2. Co-immunoprecipitation experiments provide evidence that PKC-dependent phosphorylation of TRPC1 occurs constitutively and was increased by CPA and PDBu but decreased by chelerythrine. These novel results show that PIP2 can activate TRPC1 SOCs in native vascular myocytes and plays an important role in SOC activation by CPA, BAPTA-AM and PDBu. Moreover, the permissive role of PIP2 in SOC activation requires PKC-dependent phosphorylation of TRPC1

SUMSS: A Wide-Field Radio Imaging Survey of the Southern Sky. I. Science goals, survey design and instrumentation

The Molonglo Observatory Synthesis Telescope, operating at 843 MHz with a 5 square degree field of view, is carrying out a radio imaging survey of the sky south of declination -30 deg. This survey (the Sydney University Molonglo Sky Survey, or SUMSS) produces images with a resolution of 43" x 43" cosec(Dec.) and an rms noise level of about 1 mJy/beam. SUMSS is therefore similar in sensitivity and resolution to the northern NRAO VLA Sky Survey (NVSS; Condon et al. 1998). The survey is progressing at a rate of about 1000 square degrees per year, yielding individual and statistical data for many thousands of weak radio sources. This paper describes the main characteristics of the survey, and presents sample images from the first year of observation.Comment: 27 pages, 12 figures (figures 2, 8, 10 in jpg format); AJ, in pres

Identification of floodwater source areas in Nepal using SCIMAP‐Flood

Practical approaches for managing flooding from fluvial sources are moving away from mitigation solely at the point of impact and towards integrated catchment management. This considers the source areas, flow pathways of floodwaters and the locations and exposure to the risk of communities. For a field site in southern Nepal, we analyse catchment response to a range of simulated rainfall events, which when evaluated collectively can help guide potential flood management solutions. This is achieved through the adoption of SCIMAP-Flood, a decision support framework that works at the catchment-scale to identify critical source areas for floodwaters. The SCIMAP-Flood Fitted inverse modelling approach has been applied to the East Rapti catchment, Nepal. For multiple flood impact locations throughout the catchment, SCIMAP-Flood effectively identifies locations where flood management measures would have the most positive effects on risk reduction. The results show that the spatial targeting of mitigation measures in areas of irrigated and rainfed agriculture and the prevention of deforestation or removal of shrubland would be the most effective approaches. If these actions were in the upper catchment above Hetauda or upstream of Manahari they would have the most effective reduction in the flood peak

The Distribution of H2O Maser Emission in the Nucleus of NGC 4945

We present the first interferometer map of the water maser emission in the active nucleus of NGC 4945. Although the declination of the galaxy is about -49 degrees, we were able to make the observations with the southernmost antennas of the Very Long Baseline Array. Strong maser emission is present in three velocity ranges, one near the systemic velocity and two shifted roughly symmetrically by +/-(100-150) km/s. This is the first detection of highly blue-shifted water emission in NGC 4945. We determined the position of the maser to be RA(B1950)= 13 02 32.28 +/- 0.02 ; Dec(B1950)= -49 12 01.9 +/- 0.1. The uncertainties in earlier estimates are at least several arcseconds. The maser lies within 2'' (36 pc at a distance of 3.7 Mpc) of the peaks in 1.4 GHz continuum and 1.6 micron emission from the nucleus. The mappable maser emission is distributed roughly linearly over about 40 milliarcseconds (0.7 pc) at a position angle of about 45 degrees, which is close to the 43 +/- 2 degree position angle of the galactic disk. The red and blue-shifted emission symmetrically stradle the systemic emission on the sky, which suggests material in edge-on circular motion around a central object. The position-velocity structure indicates a binding mass of about one million Suns, within a volume of radius about 0.3 pc. This implies that the central engine radiates on the order of 10% of its Eddington luminosity.Comment: 18 pages, including 5 Postscript figures. Accepted for publication in ApJ Letter

1981 Hay Day report : Forage Systems Research Center, Linneus, Mo.

Includes reprints of articles from "UMC science and technology guide", "Making and storing quality hay" and "Large round balers.

Activation of native TRPC1/C5/C6 channels by endothelin-1 is mediated by both PIP3 and PIP2 in rabbit coronary artery myocytes

We investigate activation mechanisms of native TRPC1/C5/C6 channels (termed TRPC1 channels) by stimulation of endothelin-1 (ET-1) receptor subtypes in freshly dispersed rabbit coronary artery myocytes using single channel recording and immunoprecipitation techniques. ET-1 evoked non-selective cation channel currents with a unitary conductance of 2.6 pS which were not inhibited by either ET(A) or ET(B) receptor antagonists, respectively BQ-123 and BQ788, when administered separately. However, in the presence of both antagonists, ET-1-evoked channel activity was abolished indicating that both ET(A) and ET(B) receptor stimulation activate this conductance. Stimulation of both ET(A) and ET(B) receptors evoked channel activity which was inhibited by the protein kinase C (PKC) inhibitor chelerythrine and by anti-TRPC1 antibodies indicating that activation of both receptor subtypes causes TRPC1 channel activation by a PKC-dependent mechanism. ET(A) receptor-mediated TRPC1 channel activity was selectively inhibited by phosphoinositol-3-kinase (PI-3-kinase) inhibitors wortmannin (50 nm) and PI-828 and by antibodies raised against phosphoinositol-3,4,5-trisphosphate (PIP(3)), the product of PI-3-kinase-mediated phosphorylation of phosphatidylinositol 4,5-bisphosphate (PIP(2)). Moreover, exogenous application of diC8-PIP(3) stimulated PKC-dependent TRPC1 channel activity. These results indicate that stimulation of ET(A) receptors evokes PKC-dependent TRPC1 channel activity through activation of PI-3-kinase and generation of PIP(3). In contrast, ET(B) receptor-mediated TRPC1 channel activity was inhibited by the PI-phospholipase C (PI-PLC) inhibitor U73122. 1-Oleoyl-2-acetyl-sn-glycerol (OAG), an analogue of diacylglycerol (DAG), which is a product of PI-PLC, also activated PKC-dependent TRPC1 channel activity. OAG-induced TRPC1 channel activity was inhibited by anti-phosphoinositol-4,5-bisphosphate (PIP(2)) antibodies and high concentrations of wortmannin (20 μm) which depleted tissue PIP(2) levels. In addition exogenous application of diC8-PIP(2) activated PKC-dependent TRPC1 channel activity. These data indicate that stimulation of ET(B) receptors evokes PKC-dependent TRPC1 activity through PI-PLC-mediated generation of DAG and requires a permissive role of PIP(2). In conclusion, we provide the first evidence that stimulation of ET(A) and ET(B) receptors activate native PKC-dependent TRPC1 channels through two distinct phospholipids pathways involving a novel action of PIP(3), in addition to PIP(2), in rabbit coronary artery myocytes