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Optimization of Polygalacturonase Production from a Newly Isolated Thalassospira frigidphilosprofundus to Use in Pectin Hydrolysis: Statistical Approach
No full textThe present study deals with the production of cold active polygalacturonase (PGase) by submerged fermentation using Thalassospira frigidphilosprofundus, a novel species isolated from deep waters of Bay of Bengal. Nonlinear models were applied to optimize the medium components for enhanced production of PGase. Taguchi orthogonal array design was adopted to evaluate the factors influencing the yield of PGase, followed by the central composite design (CCD) of response surface methodology (RSM) to identify the optimum concentrations of the key factors responsible for PGase production. Data obtained from the above mentioned statistical experimental design was used for final optimization study by linking the artificial neural network and genetic algorithm (ANN-GA). Using ANN-GA hybrid model, the maximum PGase activity (32.54 U/mL) was achieved at the optimized concentrations of medium components. In a comparison between the optimal output of RSM and ANN-GA hybrid, the latter favored the production of PGase. In addition, the study also focused on the determination of factors responsible for pectin hydrolysis by crude pectinase extracted from T. frigidphilosprofundus through the central composite design. Results indicated 80% degradation of pectin in banana fiber at 20 ∘ C in 120 min, suggesting the scope of cold active PGase usage in the treatment of raw banana fibers
Implementation of the International Association of Diabetes and Pregnancy Study Groups Criteria: Not Always a Cause for Concern
No full text2011): “Unobserved Investment, Endogenous Quality, and Trade
No full textAbstract A seller can make investments that affect a tradable asset's future returns. The potential buyer of the asset cannot observe the seller's investment prior to trade, nor does he receive any signal of it, nor can he verify it in anyway after trade. Despite this severe moral hazard problem, this paper shows the seller will invest with positive probability in equilibrium. The outcome of the game is sensitive to the distribution of bargaining power between the parties, with a holdup problem existing if the buyer has the bargaining power. A consequence of the holdup problem is welfare-reducing distortions in investment level, but not necessarily a reduction in the expected amount invested vis-à-vis the situation without holdup
Demographic risk transfer: is it worth for annuity providers?
No full textAbstract Longevity risk transfer is a popular choice for annuity providers such as pension funds. This paper formalizes the trade-off between the cost and the risk relief of such choice, when the annuity provider uses valueat-risk to assess risk. Using first-order approximations we show that, if the transfer is fairly priced and the aim of the fund is to maximize returns, the funds' alternatives can be represented in the plane expected returnVaR. We build a risk-return frontier, along which the optimal transfer choices of the fund are located and calibrated it to the 2010 UK annuity and bond market. The activity of pension funds and their asset managers is likely to be stimulated by both the current and forecasted reduction in public provision of pensions. The high level of public deficit with respect to GDP in a number of developed countries offers to private providers of annuities a unique opportunity to develop their activity and increase their business. This opportunity goes hands in hands with major risks, linked to the overall economic and demographic situation and to the relative inadequacy of theoretical risk management tools to cope with the many facets of actual businesses. This endangers the growth and success perspectives of private annuity providers. Longevity risk -i.e. the risk of unexpected improvements in survivorshipis by now perceived as an important threat to the safety of annuity providers, such as pension funds. These institutions run the risk of seeing their liabilities increase over time, because their members survive more than predicted, i.e. the actual survival rate is greater than the forecasted one. As of 2007, the exposure of pension funds and other annuity providers to unexpected improvements in life expectancy has been computed to be 400 billion USD for the US and UK, more than 20 trillion USD worldwide (see Annuity providers are also exposed to financial risks on both assets and liabilities, as soon as the latter are fairly evaluated. In principle, accounting fo
Kent Academic Repository Full text document (pdf) Versions of research Citation for published version Computer Science at Kent MeshTree: A Delay-optimised Overlay Mul- ticast Tree Building Protocol
No full textAbstract We study decentralised low delay degree-constrained overlay multicast tree construction for single source real-time applications. This optimisation problem is NP-hard even if computed centrally. We identify two problems in traditional distributed solutions, namely the greedy problem and delaycost trade-off. By offering solutions to these problems, we propose a new self-organising distributed tree building protocol called MeshTree. The main idea is to embed the delivery tree in a degree-bounded mesh containing many low cost links. Our simulation results show that MeshTree is comparable to the centralised Compact Tree algorithm, and always outperforms existing distributed solutions in delay optimisation. In addition, it always yields trees with lower cost and traffic redundancy
Application-Controlled Demand Paging for Out-of-Core Visualization Application-Controlled Demand Paging for Out-of-Core Visualization
No full textAbstract In the area of scientific visualization, input data sets are often very large. In visualization of Computational Fluid Dynamics (CFD) in particular, input data sets today can surpass 100 Gbytes, and are expected to scale with the ability of supercomputers to generate them. Some visualization tools already partition large data sets into segments, and load appropriate segments as they are needed. However, this does not remove the problem for two reasons: 1) there are data sets for which even the individual segments are too large for the largest graphics workstations, 2) many practitioners do not have access to workstations with the memory capacity required to load even a segment, especially since the state-of-the-art visualization tools tend to be developed by researchers with much more powerful machines. When the size of the data that must be accessed is larger than the size of memory, some form of virtual memory is simply required. This may be by segmentation, paging, or by paged segments. In this paper we demonstrate that complete reliance on operating system virtual memory for out-of-core visualization leads to poor performance. We then describe a paged segment system that we have implemented, and explore the principles of memory management that can be employed by the application for out-of-core visualization. We show that application control over some of these can significantly improve performance. We show that sparse traversal can be exploited by loading only those data actually required. We show also that application control over data loading can be exploited by 1) loading data from alternative storage format (in particular 3-dimensional data stored in sub-cubes), 2) controlling the page size. Both of these techniques effectively reduce the total memory required by visualization at run-time. We also describe experiments we have done on remote out-of-core visualization (when pages are read by demand from remote disk) whose results are promising. Abstract In the area of scientific visualization, input data sets are often very large. In visualization of Computational Fluid Dynamics (CFD) in particular, input data sets today can surpass 100 Gbytes, and are expected to scale with the ability of supercomputers to generate them. Some visualization tools already partition large data sets into segments, and load appropriate segments as they are needed. However, this does not remove the problem for two reasons: 1) there are data sets for which even the individual segments are too large for the largest graphics workstations, 2) many practitioners do not have access to workstations with the memory capacity required to load even a segment, especially since the state-of-the-art visualization tools tend to be developed by researchers with much more powerful machines. When the size of the data that must be accessed is larger than the size of memory, some form of virtual memory is simply required. This may be by segmentation, paging, or by paged segments. In this paper we demonstrate that complete reliance on operating system virtual memory for out-of-core visualization leads to egregious performance. We then describe a paged segment system that we have implemented, and explore the principles of memory management that can be employed by the application for out-ofcore visualization. We show that application control over some of these can significantly improve performance. We show that sparse traversal can be exploited by loading only those data actually required. We show also that application control over data loading can be exploited by 1) loading data from alternative storage format (in particular 3-dimensional data stored in subcubes), 2) controlling the page size. Both of these techniques effectively reduce the total memory required by visualization at run-time. We also describe experiments we have done on remote out-of-core visualization (when pages are read by demand from remote disk) whose results are promising
Explaining Unwanted Behaviours in Context
No full textAbstract Mobile malware has been increasingly identified based on unwanted behaviours like sending premium SMS messages. However, unwanted behaviours for a group of apps can be normal for another, i.e., they are contextsensitive. We develop an approach to automatically explain unwanted behaviours in context and evaluate the automatic explanations via a user-study with favourable results. These explanations not only state whether an app is malware but also elaborate how and in what kind of context a decision was made
Entrepreneurship Research Con-ference
No full textEXECUTIVE SUMMARY The term "entrepreneurial orientation" has been used to refer to the strategymaking processes and styles of firms that engage in entrepreneurial activities. A popular model of entrepreneurial orientation (EO) suggests that there are five dimensions of EO-autonomy, innovativeness, risk taking, proactiveness, and competitive aggressiveness (Lumpkin and Dess 1996
CHEMICAL PHYSICS LETTERS Probing the electronic structure of small iron clusters
No full textAbstract The electronic structure of small iron clusters is probed with size-selected anion photoelectron spectroscopy. The photoelectron spectra for Fe~ to Fe~6 exhibit consistently sharp features near the threshold and their spectral changes correlate well with changes of their chemical reactivity. Extended Hiickei calculations, based on body centered cubic structures for F% to Fe~6, provide a reasonable explanation of the experiment. These calculations also yield insights into the cluster magnetism and allow an interpretation of the cluster chemical reactivity based on their electronic structure
