28,925 research outputs found
On Sasaki-Einstein manifolds in dimension five
We prove the existence of Sasaki-Einstein metrics on certain simply connected
5-manifolds where until now existence was unknown. All of these manifolds have
non-trivial torsion classes. On several of these we show that there are a
countable infinity of deformation classes of Sasaki-Einstein structures.Comment: 18 pages, Exposition was expanded and a reference adde
High order quantum decoherence via multi-particle amplitude for boson system
In this paper we depict the high order quantum coherence of a boson system by
using the multi-particle wave amplitude, whose norm square is just the high
order correlation function. This multi-time amplitude can be shown to be a
superposition of several "multi-particle paths". When the environment or a
apparatus entangles with them to form a generalized "which-way" measurement for
many particle system, the quantum decoherence happens in the high order case
dynamically. An explicit illustration is also given with an intracavity system
of two modes interacting with a moving mirror.Comment: 7 pages, revtex, 4 eps figure
Breaking conjugate pairing in thermostatted billiards by magnetic field
We demonstrate that in the thermostatted three-dimensional Lorentz gas the
symmetry of the Lyapunov spectrum can be broken by adding to the system an
external magnetic field not perpendicular to the electric field. For
perpendicular field vectors, there is a Hamiltonian reformulation of the
dynamics and the conjugate pairing rule still holds. This indicates that
symmetric Lyapunov spectra has nothing to do with time reversal symmetry or
reversibility; instead, it seems to be related to the existence of a
Hamiltonian connection.Comment: 4 pages, 3 figure
Project characteristics for design and build procurement in Malaysian construction industry
Design & Build procurement approach is one of the procurement methods which is known to be widely gaining popularity in order to serve the modern day construction clients desire of having a constructed facility. To effectively service the market-driven expansion of this project delivery strategy in the construction community, a fundamental understanding of the characteristics of the Design & Build procurement approach is necessary. This study is aimed at appraising the Design & Build procurement approach in the Malaysian construction industry based on current practice through identifying the characteristics of the procurement approach. For this purpose, a detailed literature review of the Design & Build characteristics was conducted and data was collected from a two round Delphi questionnaire survey conducted with experienced professionals that have vast experience in the Design & Build procurement practice. The relative importance of these characteristics were quantified by the relative importance index method demonstrating their level of priority. The key findings in the study showed that the practice of the procurement approach in Malaysia is most importantly characterized by the fact that it is most suitable for projects that are complex in nature, while âeffective client representationâ is the least important characteristic of the Design & Build procurement approach with regard to the Malaysian construction industry. It is expected that with the consideration of these characteristics of the D&B procurement approach, it will consequently result in the overall improvement in the performance of the Malaysian construction industry in relation to project delivery
Global liquidity and financial flows to developing countries: new trends in emerging markets and their implications
This paper attempts to examine: (i) the factors responsible for this revival and surge in capital flows into developing countries; (ii) the qualitative changes in financial integration that are accompanying this surge; and (iii) the impact that this surge is having on financial volatility and vulnerability, macroeconomic management and growth, in countries that have been âsuccessfulâ in attracting such flows. It argues that in the wake of financial liberalization that facilitates cross-border flows of capital, supply-side factors rather than the financing requirements of developing countries, explain the surge. Financial liberalization and the globalization of finance, have also resulted in changes in the financial structure â the markets, institutions and instruments that define the global financial architecture â that are increasing risk and financial fragility. Associated with this increasing risk, are changes in the business practices and motivations of financial firms that reduce the role of finance in ensuring broad-based economic growth.
The Penalty of a Long, Hot Summer. Photosynthetic Acclimation to High CO2 and Continuous Light in âLiving Fossilâ Conifers
Deciduous forests covered the ice-free polar regions 280 to 40 million years ago under warm âgreenhouseâ climates and high atmospheric pCO2. Their deciduous habit is frequently interpreted as an adaptation for minimizing carbon losses during winter, but experiments with âliving fossilsâ in a simulated warm polar environment refute this explanation. Measured carbon losses through leaf abscission of deciduous trees are significantly greater than losses through winter respiration in evergreens, yet annual rates of primary productivity are similar in all species. Here, we investigate mechanisms underlying this apparent paradox by measuring the seasonal patterns of leaf photosynthesis (A) under pCO2 enrichment in the same trees. During spring, A increased significantly in coastal redwood (Sequoia sempervirens), dawn redwood (Metasequoia glyptostroboides), and swamp cypress (Taxodium distichum) at an elevated pCO2 of 80 Pa compared with controls at 40 Pa. However, strong acclimation in Rubisco carboxylation capacity (Vc,max) completely offset the CO2 response of A in all species by the end of 6 weeks of continuous illumination in the simulated polar summer. Further measurements demonstrated the temporary nature of acclimation, with increases in Vc,max during autumn restoring the CO2 sensitivity of A. Contrary to expectations, the acclimation of Vc,max was not always accompanied by accumulation of leaf carbohydrates, but was associated with a decline in leaf nitrogen in summer, suggesting an alteration of the balance in plant sources and sinks for carbon and nitrogen. Preliminary calculations using A indicated that winter carbon losses through deciduous leaf abscission and respiration were recovered by 10 to 25 d of canopy carbon fixation during summer, thereby explaining the productivity paradox
The effects of water quality on freshwater fish populations - final report
There is a need to determine quantitative relationships between fishery status and water quality in order to make informed judgements concerning fishery health and the setting of environmental quality standards for fishery protection. Such relationships would also assist in the
formulation of a system for classifying fisheries.
A national database of fisheries and water quality has been collated from the archives of pollution control authorities throughout the UK. A number of probable and potential water quality effects on fish populations have been identified from a thorough analysis of the database, notwithstanding large confounding effects such as habitat variation and fish mobility, and the generally sparse nature of water
quality information. A number of different approaches to data analysis was utilised, and the value of each has been appraised. Recommendations concerning the integration of water quality assessment approaches have been made and further research on fishery status, and its measurement,
in relation to water quality has been suggested
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