The effect of network structure on phase transitions in queuing networks

Recently, De Martino et al have presented a general framework for the study of transportation phenomena on complex networks. One of their most significant achievements was a deeper understanding of the phase transition from the uncongested to the congested phase at a critical traffic load. In this paper, we also study phase transition in transportation networks using a discrete time random walk model. Our aim is to establish a direct connection between the structure of the graph and the value of the critical traffic load. Applying spectral graph theory, we show that the original results of De Martino et al showing that the critical loading depends only on the degree sequence of the graph -- suggesting that different graphs with the same degree sequence have the same critical loading if all other circumstances are fixed -- is valid only if the graph is dense enough. For sparse graphs, higher order corrections, related to the local structure of the network, appear.Comment: 12 pages, 7 figure

Non-resonant microwave absorption studies of superconducting MgB_2

Non-resonant microwave absorption(NRMA) studies of superconducting MgB_2 at a frequency of 9.43 GHz in the field range -50 Gauss to 5000 Gauss are reported. The NRMA results indicate near absence of intergranular weak links. A linear temperature dependence of the lower critical field H_c1 is observed indicating a non s-wave superconductivity. However, the phase reversal of the NRMA signal which could suggest d-wave symmetry is also not observed.Comment: 8 pages, 2 figure

Extraction of manganese from Ferro-manganese slag

In the present investigation an attempt has been made to recover manganese from ferro-manganese slag of ferro-alloy plant. Roasting and leaching are the techniques used to recover- manganese. Roasting has been carried out by mixing the slag with CaO and CaCO3, at 1200Cfor 2 hours. The leaching of the roasted mass has been carried out in ferric chloride solution alone, as well as in presence of sucrose in ferric chloride solution. The optimum condit-ions have been established by varying the parameters like concentration of leaching agent, percent solids, particle size of the slag, temperature and time of leaching. It is possible to recover 87% of manganese from the ferro-manganese slag of 200# at a temperature of 80°C, 2 hours of leaching time and 5% solids in 0. 154 M ferric chloride solution. It has been found that the presence of sucrose in ferric chloride solution enhances the rate & recovery)recovery of manganese from slag

Chemopreventive Potential of Synergy1 and Soybean in Reducing Azoxymethane-Induced Aberrant Crypt Foci in Fisher 344 Male Rats

Synergy1, a prebiotic composed of Inulin and Oligofructose (1 : 1). Soybean meal is a natural source of isoflavones. The objective was to investigate the effects of feeding Synergy1 and SM on the incidence of azoxymethane- (AOM-) induced aberrant crypt foci (ACF) in Fisher 344 male rats. Rats (54) were randomly assigned to 9 groups (n = 6). Control group (C) was fed AIN-93G and treatment groups Syn1 and SM at 5% and 10% singly and in combinations. Rats were injected with two s/c injections of AOM at 7 and 8 weeks of age at 16 mg/kg body weight and killed at 17 weeks by CO2 asphyxiation. Colonic ACF enumeration and hepatic enzyme activities were measured. Reductions (%) in total ACF among treatment groups fed combinations were higher (67–77) compared to groups fed singly (52–64). Synergistic mechanisms among phytochemicals may be responsible suggesting protective role in colon carcinogenesis with implications in food product development

Tea mosquito bug (Helopeltis spp.) – A devastating pest of cashew plantations in India: A review

More than 32 countries are growing cashew in the world, wherein India occupies largest area under cashew plantations (20%) and earning foreign exchange of over 5 000 crores per annum through export of cashew kernels and cashew nut shell liquid. Often, there is a serious loss in cashew nut yield due to attack of tea mosquito bug (Helopeltis spp., Heteroptera: Miridae) which is a major sucking pest of cashew plantations in India. Under severe out break conditions, yield losses are as high as 40-50%. There are three common species of Helopeltis, viz. H. antonii Signoret, H. bradyi Waterhouse and H. theivora Waterhouse found in west coast and H. antonii is most predominant in the east coast, though in east coast its occurrence is prevalent from Tamil Nadu to Odisha. Whereas, H. theivora is predominant species in north-east region. Besides cashew, a large number of host plants like, tea, guava, cocoa, neem, cinchona etc. are reported. The seasonality study suggested that the population of tea mosquito bug reaches its peak during the flushing, flowering and fruiting season in cashew, i.e. from November to February. As a management strategy, varietal screening suggested that no cashew varieties are resistant to tea mosquito bug infestation but Dhana and Bhaskara varieties are moderately susceptible. Therefore, even today only chemical means of tea mosquito bug management is adopted under commercial cashew plantation. As a biological control strategy, the solitary egg parasitoids, viz. Telenomus cuspis, Chaetostricha sp. and Erythmelus helopeltidis Gahan were specifically promising against Helopeltis. The adult parasitoid, Leiophron sp. is additional asset for natural control strategies of Helopeltis spp. on cashew. Recent researches have incorporated 117 species of spiders and 18 species of reduviids into cashew management strategies. Laboratory mass culture techniques of reduviids have also been standardized using wax moth larvae as prey. Adults of H. antonii and H. theivora were found to be infested by predatory mite, Leptus sp. attached ecdysial line from head and thorax. Moreover, sex pheromone based technology development is the need of the hour to manage this pest. In this paper, efforts have been made to review the literature pertaining to the pest taxonomy, biology, distribution, host plants, nature of damage, seasonality and management strategy of Helopeltis spp. focusing on Indian subcontinent, so as to bring out non-chemical based management strategies

Combinational Effects of Prebiotics and Soybean against Azoxymethane-Induced Colon Cancer In Vivo

Prebiotic fructans are nondigestible carbohydrates with numerous health benefits. Soybean is a rich source of phytonutrients such as isoflavones. The objective of this study was to evaluate the chemopreventive effects of prebiotics (Synergy1) and soybean meal (SM) at 5% and 10% levels alone and in combination on azoxymethane- (AOM-) induced colon carcinogenesis. After one wk of acclimatization, Fisher 344 male rats (N = 90) were randomly assigned to 9 groups (n = 10). Control rats (C) were fed AIN-93G/M. Two s/c injections of AOM were administered to rats at 7 and 8 wk of age at 16 mg/kg body weight. Rats were killed by CO2 asphyxiation at 45 wk. Tumor incidence (%) in treatment groups ranged from 40 to 75 compared to 100 in C. Results indicate that feeding prebiotics and soybean in combination significantly reduced incidence of AOM-induced colon tumors with implications for food industry in the food-product development

Continuous Uniform Finite Time Stabilization of Planar Controllable Systems

Continuous homogeneous controllers are utilized in a full state feedback setting for the uniform finite time stabilization of a perturbed double integrator in the presence of uniformly decaying piecewise continuous disturbances. Semiglobal strong $\mathcal{C}^1$ Lyapunov functions are identified to establish uniform asymptotic stability of the closed-loop planar system. Uniform finite time stability is then proved by extending the homogeneity principle of discontinuous systems to the continuous case with uniformly decaying piecewise continuous nonhomogeneous disturbances. A finite upper bound on the settling time is also computed. The results extend the existing literature on homogeneity and finite time stability by both presenting uniform finite time stabilization and dealing with a broader class of nonhomogeneous disturbances for planar controllable systems while also proposing a new class of homogeneous continuous controllers

Microfabrication of vertical-cavity surface-emitting laser cavities

We have reduced the threshold voltages and currents of vertical cavity surface emitting lasers by using dielectric high reflectivity mirrors which were deposited after the diode fabrication step. This device fabrication sequence is able to correct for inaccuracies in the crystal growth and allows the future development of more complex laser structures. The quantum-well based laser diodes were demonstrated at 0.72 µm, 0.85 µm, and 1.55 µm. Threshold currents and voltages of our 0.85 µm lasers were 2.8 mA at 1.7 V pulsed, and 4 mA when cw-pumped. The threshold currents of 5x7 µm^2 area 1.55 µm devices were 17 mA