Rhythmic inhibition allows neural networks to search for maximally consistent states

Gamma-band rhythmic inhibition is a ubiquitous phenomenon in neural circuits yet its computational role still remains elusive. We show that a model of Gamma-band rhythmic inhibition allows networks of coupled cortical circuit motifs to search for network configurations that best reconcile external inputs with an internal consistency model encoded in the network connectivity. We show that Hebbian plasticity allows the networks to learn the consistency model by example. The search dynamics driven by rhythmic inhibition enable the described networks to solve difficult constraint satisfaction problems without making assumptions about the form of stochastic fluctuations in the network. We show that the search dynamics are well approximated by a stochastic sampling process. We use the described networks to reproduce perceptual multi-stability phenomena with switching times that are a good match to experimental data and show that they provide a general neural framework which can be used to model other 'perceptual inference' phenomena

Development of Affordable Machine for Sizing Egyptian Onion

Size grading is an important operation in food processing for the onion export industry in particular. The aim of this work was to develop an appropriate machine for sizing onions, reduce losses and reduce grading costs. Maximum sizing efficiency obtained was 94.9±2.82 % at zero longitudinal angle and at a belt speed of (0.23 m/s), while it was 94.5±3.69% at 10o longitudinal angle for the same belt speed. The overall average of the sizing efficiency (94.33%) was recorded at 20o side angle and the highest grading capacity (1.72 t/h) was obtained at 10o side angle and 10o longitudinal angle. Total costs of grading the produce were 3.89 LE/t. (0.7 US$/t). This machine has the potential to size other crops like potatoes, tomatoes, apples and citrus fruits

Equilibrium Moisture Content of Some Bioplastic Materials for Agricultural Use

This work focused on the determination of equilibrium moisture content (EMC) of some bioplastic materials that could be used for agricultural foil mulch. Equilibrium moisture content (EMC) is very important to determine the desirable conditions of microorganism’s growth, which causes material deterioration and degradation. Thus, this work aimed to determine the EMC of some commercial bioplastic mulch such as (Bioflex, Ecoflex, Chitosan, Mater-bi, and Bi-OPL). The bioplastic materials were put under different temperature (10-50°C) and relative humidity (43-95%) Conditions. The results indicated that the EMC of all materials increased while increasing the relative humidity, but decreased with increasing temperature. But the relative humidity has a greater effect on the change of moisture content (MC) than the effect of temperature. The data revealed that both of Mater-Bi and Chitosan has a great effect by changing the relative humidity from 43 to 95%, which increased the EMC by 9.87 and 12.22%, respectively. On the other hand, there is a small effect on the EMC with relative humidity changes on each of Ecoflex (1.41%), Bioflex (2.4%) and Bi-OPL (0.5%)

Mechanical properties of some bioplastics under different soil types used as biodegradable drip tubes

A lack of degradability and the closing of landfill sites, as well as growing water and land pollution problems, have led to concern about plastics.  With the excessive use of plastics and increasing pressure being placed on capacities available for plastic waste disposal, the need for biodegradable plastics and biodegradation of plastic wastes has assumed increasing importance in the last few years.  Awareness of the waste problem and its impact on the environment has awakened new interest in the area of degradable polymers.  The biodegradation of five different types of commercial bioplastics available on the market as agricultural mulch film (Bioflex, Ecoflex, Mater Bi, Chitosan and Bi-OPL foil) was evaluated under different soil types (Sandy, Sandy Loam and Loamy soil) to study the material stability and life expectancy, and to establish which was better to be used in the production of biodegradable drip tubes for drip irrigation system.  Weight loss, tensile strength (TS) loss and loss of percentage elongation (%E) were measured in 0, 1, 2, 3, 4, and 5 months.  Bi-OPL appeared to possess a high resistance to soil types, as indicated by lower changes in tensile strength, weight losses and with maximum 26% decreased in elongation at break.  At the end of the experiments, Chitosan films were completely degraded in all soil types and both surface and subsurface positions.  The starch contained in Mater Bi samples was degraded after 60 days with 4% weight losses and leads to 3% observed losses in tensile strength.  Weight losses of Ecoflex and Bioflex were greater after three months (more than 30%) than that previously (5% to 10%).  The tensile strength of both Ecoflex and Bioflex films decreased about 4% and 3% respectively in loamy soil and loamy sand soil by Week 12, More than 40% of the elongation capacity of the films were lost by Month 3 in both soil types.  The decrease of %E in both films was slightly faster in loamy and loamy sand soil than in sandy soil.Keywords: biodegradation, soil, Bi-OPL, Chitosan, Mater Bi, Bioflex, Ecoflex, drip tubes Citation: Mostafa, H. M., H. Sourell, and F. J. Bockisch.  Mechanical properties of some bioplastics under different soil types used as biodegradable drip tubes.  Agric Eng Int: CIGR Journal, 2010, 12(1): 12-21

Available nutrients and some soil properties of El-Qasr soils, El-Dakhla Oasis, Egypt

Ten surface soil samples (0-30 cm) were collected from El-Qasr village, El-Dakhla Oasis, New Valley, Egypt to investigate some soil properties and nutrients availability. The results revealed that most of the soil texture varied clay loam to sandy clay loam. The mean values of bulk density (BD), soil pH, electric conductivity (EC), saturation percentage (SP), calcium carbonate (CaCO3), cation exchangeable capacity (CEC), organic matter (OM), and sodium adsorption ratio (SAR) were 1.42 gcm3, 7.89, 3.34 dSm-1, 52.10%, 7.46 %, 28.08 cmol (+) kg-1, and 3.65, respectively. The mean values of N, P, and K were 99.37, 31.32, 121.93, mg/kg, respectively. Meanwhile, the mean values of Fe, Mn, Cu and Zn were 27.39, 18.38, 0.48, and 3.48 mgkg-1, respectively. The correlations coefficient of NPK was strongly positively significant relationship with clay, OM, CEC, and SAR, but they negatively correlated with pH, EC, CaCO3. Meanwhile, Fe, Mn, and Cu were positively correlated with EC, CaCO3, while they negatively correlated with clay, pH, OM, CEC, and SAR. Also, Zn was negatively correlated with clay, pH, EC, OM, and CaCO3, and it positively correlated with CEC and SAR

Formulation of Seawater Flow Exergy Using Accurate Thermodynamic Data

Seawater is a complex electrolyte solution of water and salts with sodium chloride as the major constituent. However, the thermodynamic properties of seawater are considerably different from those of aqueous sodium chloride solution. In the literature, exergy analyses of seawater desalination systems have sometimes modeled seawater by sodium chloride solutions of equivalent salt content or salinity; however, such matching does not bring all important properties of the two solutions into agreement. Furthermore, some published studies attempt to represent sodium chloride solutions as a specific model for an ideal mixture of liquid water and solid sodium chloride, which is shown to have serious shortcomings. In this paper, the most up-to-date thermodynamic properties of seawater are compared with those of aqueous sodium chloride solution as well as the ideal mixture model. The flow exergy is calculated using various models and the results are compared. In addition, the minimum work required to desalinate a unit mass of fresh water from seawater of varying salinity is calculated using these models. The flow exergy calculated using the ideal mixture model in question is about 50% less than that of seawater. Accordingly, the minimum desalination work is underpredicted by about 50% when calculating it using that ideal mixture model. This consequently shows that exergy analysis and the second law efficiency calculations performed using the ideal mixture model is comparatively far from the actual values.Center for Clean Water and Clean Energy at MIT and KFUP

What information can we obtain from the yield ratio π−/π+\pi^-/\pi^+ in heavy-ion collisions ?

The recently reported data on the yield ratio $\pi^-/\pi^+$ in central rapidity region of heavy-ion collisions are analyzed by theoretical formula which accounts for Coulomb interaction between central charged fragment (CCF) consisting of nearly stopped nucleons with effective charge Z_{\mbox{\scriptsize eff}} and charged pions produced in the same region of the phase space. The Coulomb wave function method is used instead of the usual Gamow factor in order to account for the finite production range of pions, $\beta$. For Gaussian shape of the pion production sources it results in a quasi-scaling in $\beta$ and Z_{\mbox{\scriptsize eff}} which makes determination of parameters $\beta$ and Z_{\mbox{\scriptsize eff}} from the existing experimental data difficult. Only sufficiently accurate data taken in the extreme small $m_{\scriptscriptstyle T}$-$m_{\pi}$ region, where this quasi-scaling is broken, could be used for this purpose.Comment: 7 pages, Latex type, 8 figure