Liouville field theory with heavy charges. I. The pseudosphere

We work out the perturbative expansion of quantum Liouville theory on the pseudosphere starting from the semiclassical limit of a background generated by heavy charges. By solving perturbatively the Riemann-Hilbert problem for the Poincar\ue9 accessory parameters, we give in closed form the exact Green function on the background generated by one finite charge. Such a Green function is used to compute the quantum determinants i.e. the one loop corrections to known semiclassical limits thus providing the resummation of infinite classes of standard perturbative graphs. The results obtained for the one point function are compared with the bootstrap formula while those for the two point function are compared with the existing double perturbative expansion and with a degenerate case, finding complete agreement. \ua9 SISSA 2006

True substrates: The exceptional resolution and unexceptional preservation of deep time snapshots on bedding surfaces

Abstract: Rock outcrops of the sedimentary–stratigraphic record often reveal bedding planes that can be considered to be true substrates: preserved surfaces that demonstrably existed at the sediment–water or sediment–air interface at the time of deposition. These surfaces have high value as repositories of palaeoenvironmental information, revealing fossilized snapshots of microscale topography from deep time. Some true substrates are notable for their sedimentary, palaeontological and ichnological signatures that provide windows into key intervals of Earth history, but countless others occur routinely throughout the sedimentary–stratigraphic record. They frequently reveal patterns that are strikingly familiar from modern sedimentary environments, such as ripple marks, animal trackways, raindrop impressions or mudcracks: all phenomena that are apparently ephemeral in modern settings, and which form on recognizably human timescales. This paper sets out to explain why these short‐term, transient, small‐scale features are counter‐intuitively abundant within a 3.8 billion year‐long sedimentary–stratigraphic record that is known to be inherently time‐incomplete. True substrates are fundamentally related to a state of stasis in ancient sedimentation systems, and distinguishable from other types of bedding surfaces that formed from a dominance of states of deposition or erosion. Stasis is shown to play a key role in both their formation and preservation, rendering them faithful and valuable archives of palaeoenvironmental and temporal information. Further, the intersection between the time–length scale of their formative processes and outcrop expressions can be used to explain why they are so frequently encountered in outcrop investigations. Explaining true substrates as inevitable and unexceptional by‐products of the accrual of the sedimentary–stratigraphic record should shift perspectives on what can be understood about Earth history from field studies of the sedimentary–stratigraphic record. They should be recognized as providing high‐definition information about the mundane day to day operation of ancient environments, and critically assuage the argument that the incomplete sedimentary–stratigraphic record is unrepresentative of the geological past

Hyperglycaemic conditions perturb mouse oocyte in vitro developmental competence via beta-O-linked glycosylation of Heat shock protein 90

STUDY QUESTION What is the effect of beta-O-linked glycosylation (O-GlcNAcylation) on specific proteins in the cumulus-oocyte complex (COC) under hyperglycaemic conditions? SUMMARY ANSWER Heat shock protein 90 (HSP90) was identified and confirmed as being O-GlcNAcylated in mouse COCs under hyperglycaemic conditions (modelled using glucosamine), causing detrimental outcomes for embryo development. WHAT IS KNOWN ALREADY O-GlcNAcylation of proteins occurs as a result of increased activity of the hexosamine biosynthesis pathway, which provides substrates for cumulus matrix production during COC maturation, and also for O-GlcNAcylation. COCs matured under hyperglycaemic conditions have decreased developmental competence, mediated at least in part through the mechanism of increased O-GlcNAcylation. STUDY DESIGN, SIZE, DURATION This study was designed to examine the effect of hyperglycaemic conditions (using the hyperglycaemic mimetic, glucosamine) on O-GlcNAc levels in the mouse COC, and furthermore to identify potential candidate proteins which are targets of this modification, and their roles in oocyte maturation. PARTICIPANTS/MATERIALS, SETTING, METHODS COCs from 21-day-old superovulated CBA × C57BL6 F1 hybrid female mice were matured in vitro (IVM). Levels of O-GlcNAcylated proteins, HSP90 and O-GlcNAc transferase (OGT, the enzyme responsible for O-GlcNAcylation) in COCs were measured using western blot, and localization observed using immunocytochemistry. For glycosylated HSP90 levels, and to test OGT-HSP90 interaction, immunoprecipitation was performed prior to western blotting. Embryo development was assessed using in vitro fertilization and embryo culture post-maturation. MAIN RESULTS AND THE ROLE OF CHANCE Addition of the hyperglycaemic mimetic glucosamine to IVM medium for mouse COCs increased detectable O-GlcNAcylated protein levels (by western blot and immunocytochemistry), and this effect was reversed using an OGT inhibitor (P < 0.05). HSP90 was identified as a target of O-GlcNAcylation in the COC, and inhibition of HSP90 during IVM reversed glucosamine-induced decreases in oocyte developmental competence (P < 0.05). We also demonstrated the novel finding of an association between HSP90 and OGT in COCs, suggesting a possible client–chaperone relationship. LIMITATIONS, REASONS FOR CAUTION In vitro maturation of COCs was used so that treatment time could be limited to the 17 h of maturation prior to ovulation. Additionally, glucosamine, a hyperglycaemic mimetic, was used because it specifically activates the hexosamine pathway which provides the O-GlcNAc moieties. The results in this study should be confirmed using in vivo models of hyperglycaemia and different HSP90 inhibitors. WIDER IMPLICATIONS OF THE FINDINGS This study leads to a new understanding of how diabetes influences oocyte competence and provides insight into possible therapeutic interventions based on inhibiting HSP90 to improve oocyte quality.L.A. Frank, M.L. Sutton-McDowall, H.M. Brown, D.L. Russell, R.B. Gilchrist, and J.G. Thompso

Animal-borne telemetry: An integral component of the ocean observing toolkit

Animal telemetry is a powerful tool for observing marine animals and the physical environments that they inhabit, from coastal and continental shelf ecosystems to polar seas and open oceans. Satellite-linked biologgers and networks of acoustic receivers allow animals to be reliably monitored over scales of tens of meters to thousands of kilometers, giving insight into their habitat use, home range size, the phenology of migratory patterns and the biotic and abiotic factors that drive their distributions. Furthermore, physical environmental variables can be collected using animals as autonomous sampling platforms, increasing spatial and temporal coverage of global oceanographic observation systems. The use of animal telemetry, therefore, has the capacity to provide measures from a suite of essential ocean variables (EOVs) for improved monitoring of Earth's oceans. Here we outline the design features of animal telemetry systems, describe current applications and their benefits and challenges, and discuss future directions. We describe new analytical techniques that improve our ability to not only quantify animal movements but to also provide a powerful framework for comparative studies across taxa. We discuss the application of animal telemetry and its capacity to collect biotic and abiotic data, how the data collected can be incorporated into ocean observing systems, and the role these data can play in improved ocean management

Co-limitation towards lower latitudes shapes global forest diversity gradients

The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers

SELF SUFFICIENCY, DELINKAQE AND FOOD PRODUCTION: LIMITS ON AGRICULTURAL DEVELOPMENT IN AFRICA

Development strategies exist in conflict with international economic and market constraints for much of Africa. Third World commodltles in general have been in less demand, and agriculture has suffered as a result. Given the current nature of the economic system, there are few solutions for these resourcefully abundant countries other than food dependency. Development needs to occur within that context . Copyright 1984 by The Policy Studies Organization.

Feed and water deprivation has a negative but transient effect on the rumen kinetics of Bos indicus steers

The effects on rumen kinetics after feed and water had been deprived for 72 hr were studied using four fistulated Bos indicus steers. The animals were assigned in a 2x4 crossover design with two treatments: feed and water ad libitum (control) and no feed and water for 72 hr (deprived) with four steers per treatment over two time periods. Feed and water deprivation caused decreases in the numbers of cellulolytic bacteria (1.4 vs. 0.4 cfu x 10(6)/ml; p=.001), live (23.7 vs. 0.8 x 10(9)/ml; p=.001), dead (12.7 vs. 0.5 x 10(9)/ml; p=.001) and total bacterial counts (36.4 vs. 1.4 x 10(9)/ml; p=.001) at day 0, compared with the control treatment. However, the deprived group had greater numbers of cellulolytic bacteria (2.7 vs. 50.1 cfu x 10(6)/ml; p=.001), live (18.3 vs. 42.2 x 10(9)/ml; p=.001), dead (6. 5 vs. 19.1 x 10(9)/ml; p=.001) and total bacterial counts (24.8 vs. 61.3 x 10(9)/ml; p=.001) from rumen fluid on day 4, compared with the control treatment. The numbers of protozoa in rumen fluid from the deprived group were less than (551.2 vs. 2.4 x 10(3)/ml; p=.001) the control group on day 0. However, the deprived treatment had fewer protozoa in rumen fluid than the control treatment on day 4 (p=.001) and day 9 (p=.001). Volatile fatty acids and in vitro gas production as functional measurements of rumen fluid followed the same trend as the bacterial and protozoa populations. These results indicate that feed and water deprivation would have a negative but transient effect on the rumen kinetics of Bos indicus steers

ECoNet platform for collaborative logistics and transport

The development of the Port Community System (PCS) concept, as a single access point to a port, offering integrated logistics and transport services, is a complex and challenging endeavour. Effective value creation in PCS requires the integration of stakeholder’s internal processes with the collaborative activities/ processes, under an open framework. The establishment of such community thus requires a well-founded collaborative framework to integrate and coordinate the diverse IT-systems of the participating stakeholders. These IT-systems, in most of the cases, were not designed and developed for a cooperation context, leading to a complex overpriced web of disconnected systems that are difficult to manage, maintain, and adapt to the fast evolution of technologies and collaboration models. In this context, an enhanced Enterprise Collaborative Network platform is presented and discussed as an approach to support PCS

Physical Principles And Miniaturization Of Spark Assisted Chemical Engraving (Sace)

International audienc

Rotational energy transfer in collisions between CO and Ar at temperatures from 293 to 30 K

Experimental measurements and theoretical calculations are reported for rotational energy transfer in the Ar-CO system. Experiments were performed in cold uniform supersonic flows of Ar, using an infrared – vacuum ultraviolet double resonance technique to measure absolute state-to-state rate constants and total relaxation cross sections for rotational energy transfer within the (v = 2) vibrational state of CO in collision with Ar at temperatures from 30.5 to 293 K. Close-coupling calculations were also performed using a recent potential energy surface (Sumiyoshi and Endo, 2015). Very good agreement is obtained between measured and calculated values