Minimum and maximum entropy distributions for binary systems with known means and pairwise correlations

Maximum entropy models are increasingly being used to describe the collective activity of neural populations with measured mean neural activities and pairwise correlations, but the full space of probability distributions consistent with these constraints has not been explored. We provide upper and lower bounds on the entropy for the {\em minimum} entropy distribution over arbitrarily large collections of binary units with any fixed set of mean values and pairwise correlations. We also construct specific low-entropy distributions for several relevant cases. Surprisingly, the minimum entropy solution has entropy scaling logarithmically with system size for any set of first- and second-order statistics consistent with arbitrarily large systems. We further demonstrate that some sets of these low-order statistics can only be realized by small systems. Our results show how only small amounts of randomness are needed to mimic low-order statistical properties of highly entropic distributions, and we discuss some applications for engineered and biological information transmission systems.Comment: 34 pages, 7 figure

Modified ACI Drop-Weight Impact Test for Concrete.

yesACI Committee 544’s repeated drop-weight impact test for concrete is often criticized for large variations within the results. This paper identifies the sources of these large variations and accordingly suggests modifications to the ACI test. The proposed modifications were evaluated and compared to the current ACI test by conducting impact resistance tests on 40 specimens from two batches of polypropylene fiber-reinforced concrete (PPFRC). The results obtained from both methods were statistically analyzed and compared. The variations in the results were investigated within the same batch and between different batches of concrete. The impact resistance of PPFRC specimens tested with the current ACI test exhibited large coefficients of variation (COV) of 58.6% and 50.2% for the first-crack and the ultimate impact resistance, respectively. The corresponding COV for PPFRC specimens tested according to the modified technique were 39.4% and 35.2%, indicating that the reliability of the results was significantly improved. It has been shown that, using the current ACI test, the minimum number of replications needed per each concrete mixture to obtain an error below 10% was 41 compared to 20 specimens for the modified test. Although such a large number of specimens is not good enough for practical and economical reasons, the reduction presents a good step on the development of a standard impact test

Macroeconomic Variables, Government Effectiveness and Sovereign Credit Rating: A Case of Egypt

Sovereign credit rating reflects the country ability to meet its financial obligations (at present and in future) on its maturities, therefore, it is an important indicator that concerns international financial institutions and foreign investors who are interested in foreign direct investment in order to know the minimum expectation of risks that can be faced in specific country. This paper aims to i) examine the effect of macroeconomic variables on the Egyptian sovereign credit rating (SCR) and ii) also investigate the impact of investment environment (measured by government effectiveness) on the SCR using the dynamic ordinary least squares (DOLS) method over the period from 1990 to 2014.  The results indicate that GDP growth, inflation, fiscal balance, reserves, current account balance, public domestic debt, and the government effectiveness have a significant impact on the sovereign credit rating in Egypt. This study has important implications for investors and policymakers

Maximizing wheat crop yield using a mobile thresher at small holdings

This study was carried out at a private farm in Owlad Sakr District, Sharkia governorate Egypt during 2015 summer season. It aimed to maximize wheat crop yield by modifying a stationary thresher. The modification involved tractor mounting the thresher to move among the field and the thresher was attached with a feeding device and a straw container. The experiment was established and designed statistically as a factorial experiment in complete randomized blocks with three replications. The tested treatments were wheat plant feeding rate levels of 500, 700,900 and 1100 kg/h and wheat plant moisture content levels of 16%, 18% and 20% (w.b.). The obtained results showed that the modified thresher decreased the total grain losses with 45.24%, increased the threshing efficiency with 1.35%, increased the cleaning efficiency with 8.16% and decreased the threshing criterion costs with 38.24%, with the stationary thresher. So, it is recommended to apply wheat threshing using the mobile thresher

Emergency Management System Design for Accurate Data: A Case Study

In any city – smart or not – emergency response is a critical service. In smart cities, the use of technology to manage access to and dispatching of emergency vehicles is particularly important. However, when a system must manage processes spanning multiple computers, clock drift becomes a prominent issue. We show the impact that clock drift can have in a prototype emergency management dispatch system along with a case-study illustrating design techniques that can remedy this issue

Fifteen-S-hydroxyeicosatetraenoic acid (15-S-HETE) specifically antagonizes the chemotactic action and glomerular synthesis of leukotriene B4 in the rat

Fifteen-S-hydroxyeicosatetraenoic acid (15-S-HETE) specifically antagonizes the chemotactic action and glomerular synthesis of leukotriene B4 in the rat. In models of experimental glomerulonephritis, there is temporal concordance between the shift in the glomerular cellular infiltrate from neutrophils (PMN) to macrophages/monocytes and the suppression of glomerular leukotriene B4 (LTB4) generation. Since macrophages are a rich source of 15-lipoxygenase (15-LO) products, we investigated whether the principal product of arachidonate 15-lipoxy-genation, 15-S-hydroxyeicosatetraenoic acid (15-S-HETE), was capable of antagonizing the proinflammatory actions of LTB4 in the rat. PMN exhibited chemotaxis to LTB4 in a dose dependent manner with an LC50 of 10-8 M. When rat neutrophils were pre-treated with 15-S-HETE, chemotaxis to LTB4 was inhibited in a dose dependent manner (maximal at 30 µM 15-S-HETE) but, the same concentration did not inhibit chemotaxis to n-formyl-1-methionyl-1-phenylalanine (FMP). 12-S-HETE (30µM) did not inhibit chemotaxis to LTB4. Glomeruli from rats injected with nephrotoxic serum three hours earlier generated increased levels of LTB4; prior exposure of such glomeruli to 15-S-HETE totally normalized LTB4 production. The glomerular production of 15-S-HETE and LTB4 was also determined 3 hours, 72 hours and 2 weeks after administration of nephrotoxic serum. Whereas there was an early, short-lived, burst of LTB4 followed by a return to baseline levels, the production of 15-S-HETE increased steadily over the two week period and was present in amounts fivefold greater than LTB4. Thus, these studies assign a role for locally generated 15-LO derivatives in arresting LTB4-promoted PMN infiltration and suppressing LTB4 synthesis. Coupled with our previous demonstration of counterregula-tory interactions between lipoxins and cysteinyl leukotrienes, the current studies provide further support for a generalized anti-inflammatory role for 15-LO products through specific antagonism and/or inhibition of leukotriene synthesis and biologic activities

Agricultural land-use change and disappearance of farmlands in Kaduna Metropolis-Nigeria

This study assessed agricultural land-use change in Kaduna metropolis. This study combined the use of remote sensing and geographic  information system (GIS) application to ascertain the rate of agriculturalland-use change from 1980 to 2012 in the study area. The four imageries (Landsat MSS 1980, Landsat TM 1990, Landsat ETM+ 2005 and Nigeria Sat X 2012) used were classified and compared to understand the rate and extent of agricultural land-use change during the different periods. The  findings revealed that the study area experienced a significant reduction inagricultural land and these leads to continued disappearance of farmlands. Lastly, the decrease in agricultural lands leads to loss of livelihood, reduction in food supply and increase poverty. This has raised so many concerns about the sustainability of Urban and Peri Urban Agriculture (UPA) production in the study area whereby the small scale farmers are the most affected.Key Words: Land-Use, Urban, Farmers, Remote Sensing, Geographic Information System (GIS) and Kaduna, Nigeri

Power System Stabilizer Driven by an Adaptive Fuzzy Set for Better Dynamic Performance

This paper presents a novel application of a fuzzy logic controller (FLC) driven by an adaptive fuzzy set (AFS) for a power system stabilizer (PSS).The proposed FLC, driven by AFS, is compared with a classical FLC, driven by a fixed fuzzy set (FFS). Both FLC algorithms use the speed error and its rate of change as input vectors. A single generator equipped with FLC-PSS and connected to an infinite bus bar through double transmission lines is considered. Both FLCs, using AFS and FFS, are simulated and tested when the system is subjected to different step changes in the reference value. The simulation results of the proposed FLC, using the adaptive fuzzy set, give a better dynamic response of the overall system by improving the damping coefficient and decreasing the rise time and settling time compared with classical FLC using FFS. The proposed FLC using AFS also reduces the computational time of the FLC as the number of rules is reduced.

Non-inertial lateral migration of vesicles in bounded Poiseuille flow

Cross-streamline non-inertial migration of a vesicle in a bounded Poiseuille flow is investigated experimentally and numerically. The combined effects of the walls and of the curvature of the velocity profile induce a movement towards the center of the channel. A migration law (as a function of relevant structural and flow parameters) is proposed that is consistent with experimental and numerical results. This similarity law markedly differs from its analogue in unbounded geometry. The dependency on the reduced volume $\nu$ and viscosity ratio $\lambda$ is also discussed. In particular, the migration velocity becomes non monotonous as a function of $\nu$ beyond a certain $\lambda$.Comment: 5 pages, 3 figures. To appear in Phys. Fluid