Networks pervade social and economic life, and they play a prominent role in explaining a huge variety of social and economic phenomena. Standard economic theory did not give much credit to the role ...of networks until the early 1990s, but since then the study of the theory of networks has blossomed. At the heart of this research is the idea that the pattern of connections between individual rational agents shapes their actions and determines their rewards. The importance of connections has in turn motivated the study of the very processes by which networks are formed.
The growth of the Internet and assorted technologies has made it possible to collect and process detailed information on social networks. This article investigates how firms (and governments) can ...harness the power of social networks to promote their goals. We show that the optimal use of social networks leads to higher sales and greater profits. However, an increase in the level and dispersion of social interaction can increase or decrease the optimal influence strategy and profits of the player, depending on the content of the interaction. Optimal influence strategies will target individuals with low or high connections, depending on the content of interaction. Finally, the returns to investing in market research on social networks are greater in more unequal networks.
AA6082/B
4
C and AA6082/SiC were prepared via stir casting accompanied by an inert-gas to prevent oxidation. The samples for both the composites were produced with varying wt% of 0, 5, 10, 15 and 20 ...of B
4
C and SiC for their respective composites. This work gives emphasis on the comparative measurements of hardness, tensile strength, percentage elongation, Impact strength, density and porosity of the AA6082/B
4
C and AA6082/SiC composites. The microstructural was studied using X-ray diffractometer and SEM. The micro hardness in AA6082/B
4
C composites increases to 15.8% and the increase in AA6082/SiC composites is 11.9% only when compared with the base alloy whereas the increase in ultimate tensile strength for B
4
C and SiC reinforced composites was reported to be 31% and 19.1% respectively. At 20 wt% of B
4
C, hardness and tensile strength of AA6082/B
4
C composite tends to decrease due to the development of clusters and increased porosity. The transformation in the nature of material from ductile to brittle decreases the impact strength and the resistance in the flow ability presented by the hard ceramic particles lowers down the percentage elongation. Density reduces from 2.67 g/cm
3
in base alloy to 2.48 g/cm
3
in AA6082/B
4
C and 2.56 g/cm
3
in AA6082/SiC composites respectively. The formation of voids in AA6082/SiC composites makes it less porous then AA6082/B
4
C composites and this was because of the more agglomeration in SiC composites due to their high density.
Graphic Abstract
In this paper a parametric study of the wear behaviour of Aluminum matrix composites has been carried out. AA6082-T6/SiC and AA6082-T6/B
4
C composites were fabricated using stir casting technique. ...The percentage of reinforcement was taken as 5, 10, 15 and 20 wt.% for both SiC and B
4
C particulates. Dry sliding wear tests were conducted using pin-on-disc apparatus at room temperature and process optimization was done using Response surface methodology (RSM). Weight percentage (wt.%) of reinforcement, sliding speed, load and sliding distance were the four process parameters considered to analyse these composites wear behaviour. Analysis of variance (ANOVA) showed that sliding distance exerted the highest contribution (60.24 %) to AA6082-T6/SiC wear, followed by sliding speed (14.28 %), load (11.88 %) and reinforcement content (4.31 %). The same trend was found in AA6082-T6/B
4
C composites with slightly different contribution values, namely sliding distance (63.28 %), sliding speed (14.02 %), load (10.10 %) and reinforcement content (4.05 %). RSM analysis revealed that increases in the reinforcement content and sliding speed reduce the wear rate in both composites. On the other hand, increases in load and sliding distance led to higher AA6082-T6/SiC and AA6082-T6/B
4
C composites wear. The two predictive models were validated by conducting confirmation tests and certified that the developed wear predictive models are accurate and can be used as predictive tools for wear apllications.
Abstract
Global supply networks in agriculture, manufacturing, and services are a defining feature of the modern world. The efficiency and the distribution of surpluses across different parts of ...these networks depend on the choices of intermediaries. This paper conducts price formation experiments with human subjects located in large complex networks to develop a better understanding of the principles governing behavior. Our first experimental finding is that prices are larger and that trade is significantly less efficient in small-world networks as compared to random networks. Our second experimental finding is that location within a network is not an important determinant of pricing. An examination of the price dynamics suggests that traders on cheapest—and hence active—paths raise prices while those off these paths lower them. We construct an agent-based model (ABM) that embodies this rule of thumb. Simulations of this ABM yield macroscopic patterns consistent with the experimental findings. Finally, we extrapolate the ABM on to significantly larger random and small-world networks and find that network topology remains a key determinant of pricing and efficiency.
We present an approach to network formation based on the notion that social networks are formed by individual decisions that trade off the costs of forming and maintaining links against the potential ...rewards from doing so. We suppose that a link with another agent allows access, in part and in due course, to the benefits available to the latter via his own links. Thus individual links generate externalities whose value depends on the level of decay/delay associated with indirect links. A distinctive aspect of our approach is that the costs of link formation are incurred only by the person who initiates the link. This allows us to formulate the network formation process as a noncooperative game. We first provide a characterization of the architecture of equilibrium networks. We then study the dynamics of network formation. We find that individual efforts to access benefits offered by others lead, rapidly, to the emergence of an equilibrium social network, under a variety of circumstances. The limiting networks have simple architectures, e.g., the wheel, the star, or generalizations of these networks. In many cases, such networks are also socially efficient.
BILATERALISM AND FREE TRADE Goyal, Sanjeev; Joshi, Sumit
International economic review (Philadelphia),
August 2006, Volume:
47, Issue:
3
Journal Article
Peer reviewed
Open access
We study a setting with many countries; in each country there are firms that can sell in the domestic as well as foreign markets. Countries can sign bilateral free-trade agreements that lower import ...tariffs and thereby facilitate trade. We allow a country to sign any number of bilateral free-trade agreements. A profile of free-trade agreements defines the trading regime. Our principal finding is that, in symmetric settings, bilateralism is consistent with global free trade. We also explore the effects of asymmetries across countries and political economy considerations on the incentives to form trade agreements.
The importance of water quality is well understood, and it becomes even more critical when is use for drinking purposes. A case study was carried out to know the applicability of GIS tool for ...determining the quality of supply water. Water samples from 21 houses at different locations of Delhi were collected. Sample analysis was done for physicochemical parameters viz., pH, EC, TDS, Total Hardness, Total Alkalinity, Chloride, Fluoride, and Nitrate. The water quality data from these selected locations was analyzed using Geographical Information System (GIS) Technique. GIS software did interpolation through the inverse distance weighted (IDW) method to know the water quality (WQ) in different part of the city for various parameters mentioned above and prepare thematic maps from the analysis of water quality data as a database. These thematic maps show the distribution of different water quality parameters. Using Weighted Arithmetic Index (WAI) method, Water Quality Index is calculated. After that, the Drinking Water Quality Index (DWQI) map was generated using thematic layer, reclassification, and weight value assigned in weighted overlay tools in GIS software. Five categories viz., excellent, good, satisfactory, poor, and very poor is assign to describe DWQI. Out of all the selected locations, DWQI was good only at two locations, whereas, at the remaining sites, the DWQI was found satisfactory. However, the overall water quality was found suitable for human consumption. The analysis outcome was represented as maps that will be advantageous to know the water quality status for the area under study. The spatial database established can be a reliable technique for monitoring and managing water quality in the water supply system.
Mutations in several ion channel genes have been reported to cause rare cases of familial atrial fibrillation (AF).
The purpose of this study was to determine the genetic basis for AF in a family ...with autosomal dominant AF.
Family members were evaluated by 12-lead ECG, echocardiogram, signal-averaged P-wave analysis, and laboratory studies. Fourteen family members in AF-324 were studied. Six individuals had AF, with a mean age at onset of 32 years (range 16-59 years).
Compared with unaffected family members, those with AF had a longer mean QRS duration (100 vs 86 ms, P = .015) but no difference in the corrected QT interval (423 +/- 15 ms vs 421 +/- 21 ms). The known loci for AF and other cardiovascular diseases were evaluated. Evidence of linkage was obtained with marker D11S4088 located within KCNQ1, and a highly conserved serine in the third transmembrane region was found to be mutated to a proline (S209P). Compared to the wild-type channel, the S209P mutant activates more rapidly, deactivates more slowly, and has a hyperpolarizing shift in the voltage activation curve. A fraction of the mutant channels are constitutively open at all voltages, resulting in a net increase in I(Ks) current.
We identified a family with lone AF due to a mutation in the highly conserved S3 domain of KCNQ1, a region of the channel not previously implicated in the pathogenesis of AF.
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