Dynamic Analysis of the Arrow Distributed Protocol

Distributed queuing is a fundamental coordination problem that arises in a variety of applications, including distributed directories, totally ordered multicast, and distributed mutual exclusion. The arrow protocol is a solution to distributed queuing that is based on path reversal on a pre-selected spanning tree of the network. We present a novel and comprehensive competitive analysis of the arrow protocol. We consider the total cost of handling a finite number of queuing requests, which may or may not be issued concurrently, and show that the arrow protocol is -competitive to the optimal queuing protocol, where s and D are the stretch and the diameter, respectively, of the spanning tree. In addition, we show that our analysis is almost tight by proving that for every spanning tree chosen for execution, the arrow protocol is -competitive to the optimal queuing protocol. Our analysis reveals an intriguing connection between the arrow protocol and the nearest neighbor traveling salesperson tour on an appropriately defined graph.     

Monitoring persistent items in the union of distributed streams

A persistent item in a stream is one that occurs regularly in the stream without necessarily contributing significantly to the volume of the stream. Persistent items are often associated with anomalies in network streams, such as botnet traffic and click fraud. While it is important to track persistent items in an online manner, it is challenging to zero-in on such items in a massive distributed stream. We present the first communication-efficient distributed algorithms for tracking persistent items in a data stream whose elements are partitioned across many different sites. We consider both infinite window and sliding window settings, and present algorithms that can track persistent items approximately with a probabilistic guarantee on the approximation error. Our algorithms have a provably low communication cost, and a low rate of false positives and false negatives, with a high probability. We present detailed results from an experimental evaluation that show the communication cost is small, and that the false positive and false negative rates are typically much lower than theoretical guarantees.     

A novel approach for electromagnetic inverse scattering of a two‐dimensional perfect electric conductor object

A two‐dimensional shape determination technique for a perfect electric conductor target using electromagnetic inverse scattering is presented. The proposed algorithm uses the scattered field pattern and an inverse scattering technique derived from Green's function to retrieve the geometry of an unknown target. This method uses the scattering field data over a band of observation points, which is synthesized using frequency domain “method of moment” computational technique. We have verified this algorithm with four different types of numerical examples.     

Exploring the potential of complex formation between a mutant DNA and the wild type protein counterpart: a MM and MD simulation approach

We have demonstrated that the methods of molecular modeling and molecular dynamics simulation might be used to assess whether a specific mutation in the DNA would destabilize a known DNA-protein complex. The approach is based on probing the changes in the interaction that would be induced into the complex if within the already formed wild type complex the mutation could be introduced. We have used Hoxc8-DNA complex as a test system where it is known that the Hoxc8 binding affinity of the DNA is completely lost upon mutation of the DNA by replacing TAAT stretch to GCCG. Mutation was obtained by changing the relevant base pairs into the DNA of the model of the corresponding wild type complex developed by homology modeling and MD simulation in water for 2.0 ns. Comparison of the structure, dynamics and interactions between the hypothetical mutant model with those of the similarly refined wild type model shows that the loss of affinity of the mutant DNA to Hoxc8 has two different origins: (i) loss of several strong H-bonds as the direct consequences of mutation and (ii) reduced H-bonds in the common parts due to a net loss or inferior H-bonding geometry induced by the mutation as indirect effects. The net change in the interaction energy between the DNA and the protein in the best possible configuration indicated the experimentally observed destabilization effects. No significant change in the groove width was observed and no correlation was found between the water-bridges and the loss of affinity.     

Novel Technique for Saccharification of Cassava Fibrous Waste for Alcohol Production

A novel technique, involving the hydrolysis of starch present in cassava fibrous waste in shallow layers in stainless steel trays, is developed to facilitate the use of higher slurry concentrations. The use of slurry containing 30% solids, 4% sulphuric acid, 30 min saccharification time at 121°C resulted in the complete conversion of the starch into reducing sugars. The spent residue, after separation of the hydrolysate, contained about 24% of the total sugars formed and these were recovered to the extent of 90–94% by using a counter-current extraction technique. A large scale saccarification of a 75 kg batch gave 75 1 pooled hydrolysate containing 15% reducing sugars. An overall process efficiency of 76.4% was observed with the fermentation of hydrolysate pooled with the counter-current extract for alcohol production. However, fermentation of the whole saccharified pulp without the separation of the hydrolysate and acid-enzyme hydrolysis of the waste gave lower efficiencies.     

Critical evaluation of references in drug advertisements: an Indian experience

Drug advertisements have important effect in prescribing habits of physicians. WHO states that all the claims in drug advertisements should be supported by suitable documentary evidences (references). The present study evaluated citations (mentioned/not mentioned), sources (journals, books, conferences/symposia, personal testimonial, unpublished data in file) and adequacy (complete/incomplete) of the references in 585 drug advertisements supplied by medical detail persons to different clinical departments of our hospital. The references were cited only in 37.9% of the drug advertisements. In total, 1032 references (76% of journals, 15% of books, 2% of conferences/symposia, 4% of personal testimonials, 1% of unpublished data and 2% of data in file) were cited. Only 10% references of journals, 7% of books and 12% of conferences/symposia were found complete (according to standard bibliographic norms). The current situation can be improved if the government, industry and the prescribers formulate some guidelines for the mentioning of adequate references in drug advertisements.     

Techno-economic feasibility of ethanol production from fresh cassava tubers in comparison to dry cassava chips

The use of unpeeled and peeled fresh cassava tubers for the production of ethanol indicated that the extent of liquefaction and saccharification is comparable to that of dry chips. However, the fermentation efficiencies were lower by about 13 and 2% with the use of fresh unpeeled and peeled tubers respectively. The use of unpeeled tubers can be ruled out due to viscous mass formation after saccharification and consequent resistance in solid-liquid separation. The viscosity of the hydrolysed slurry of peeled tubers was nearly the double and the recovery of hydrolysate was lower by 5% as compared to those with dry chips. Additional machinery, land and building are also essential for processing fresh tubers in harvest season. These will involve heavy depreciation and financial expenses due to idling over eight months when the plant will have to depend on dry chips. The studies establish that the gain obtainable due to differences in the cost of fresh tubers and dry chips is surpassed by various techno-economic factors.     

Kiln-fired clay bricks synergizing nickel–chromium plating sludge and fly ash: mechanical characteristics and cradle-to-gate life cycle assessment

Clean Technologies and Environmental Policy - Life cycle assessment (LCA) of novel fired clay bricks with synergistic co-valorization of nickel-chrome plating sludge (NCPS) and fly ash (FA) is...     

1.0 THz GaN IMPATT Source: Effect of Parasitic Series Resistance

The degradation of high-frequency characteristics of a 1.0-THz double-drift region (DDR) impact avalanche transit time (IMPATT) diode based on wurtzite gallium nitride (Wz-GaN), due to the influence of parasitic series resistance, has been investigated. A two-dimensional (2-D) large-signal (L-S) simulation method based on a non-sinusoidal voltage excitation (NSVE) model has been used for this purpose. A comprehensive model of series resistance has been developed by considering the influence of skin effect, and the said model has been incorporated in the 2-D L-S simulation for studying the effect of RF power output and DC to RF conversion efficiency of the device. Results indicate 24.2–35.9% reduction in power output and efficiency due to the RF power dissipation in the positive series resistance. However, the device can still deliver 191.7–202.9 mW peak RF power to the load at 1.0 THz with 8.48–6.41% conversion efficiency. GaN IMPATT diodes are capable of generating higher RF power at around 1 THz than conventional diodes, but the effect of parasitic series resistance causes havoc reduction in power output and efficiency. The nature of the parasitic resistance is studied here in the level of device fabrication and optimization, which to our knowledge is not available at present.     

Symbolic agglomerative clustering for quantitative analysis of remotely sensed data

An efficient nonparametric, hierarchical, symbolic agglomerative clustering procedure based on the mutual nearest neighbourhood concept is proposed for classifying remotely sensed multispectral data. The procedure utilized a data reduction technique and an innovative symbolic concept to minimize the memory and computational time requirements. A new non-metric similarity measure and a novel method of formulation of composite symbolic objects are proposed to enrich the performance of the algorithm. A Mean Difference Index (MDI) concept for identifying the optimal number of classes was used. Experiments were conducted on IRS (Indian Remote Sensing) satellite data to authenticate the efficacy of the procedure.