Classical Analogue of the Ionic Hubbard Model

In our earlier work [M. Hafez, {\em et al.}, Phys. Lett. A {\bf 373} (2009) 4479] we employed the flow equation method to obtain a classic effective model from a quantum mechanical parent Hamiltonian called, the ionic Hubbard model (IHM). The classical ionic Hubbard model (CIHM) obtained in this way contains solely Fermionic occupation numbers of two species corresponding to particles with \up and \down spin, respectively. In this paper, we employ the transfer matrix method to analytically solve the CIHM at finite temperature in one dimension. In the limit of zero temperature, we find two insulating phases at large and small Coulomb interaction strength, $U$, mediated with a gap-less metallic phase, resulting in two continuous metal-insulator transitions. Our results are further supported with Monte Carlo simulations.Comment: 12 figure

Population fluctuation of Neoseiulus barkeri (Acari: Phytoseiidae) and its prey, Tetranychus urticae (Acari: Tetranychidae), in cucumber fields of Khorramabad, Iran

Population density and spatial distribution of Neoseiulus barkeri Hughes and its prey, Tetranychus urticae Koch, in cucumber fields of Sarab-e Chengaei region in west of the city of Khorramabad, Lorestan province, were studied in 2008-2009. The population densities of both species in the first year was higher than the second year. The population densities for T. urticae and N. barkeri reached their peaks in late July and late August 2008, respectively. In 2009, the population peaks for both species occurred in late August. The reaction of N. barkeri to different population densities of its prey, with linear regression, was described as density independent. It was also found that mated females of N. barkeri overwintered in soil. The Taylor's power law regression method was used for finding the spatial pattern of the predator and prey, which was aggregated for both species. The correlation between the population fluctuation and spatial distribution pattern of the pest and its predator can effectively help to improve the strategy for a successful IPM program

Učestalost kukca Oestrus ovis u koza u Shirazu u Južnom Iranu.

One thousand nine hundred and ninety eight heads obtained from goats slaughtered at the Fars abattoir (Shiraz, South Iran) between April 2006 and April 2007 were examined for the presence of Oestrus ovis larvae. Of the 1998 heads, 261 (13.1%) were infested with O. ovis larvae. O. ovis larvae were observed in both sexes and all age groups in each season of the year. A total of 1356 larvae were collected. The overall larval intensity for the infested goats was 5.2, with 3.2 in spring, 3.8 in summer, 4.6 in autumn and 6.8 in winter. Prevalence ranged from 6.6% in spring to 17.9% in winter. Increased infestation was observed in older animals.Ukupno je pregledano 1998 glava koza zaklanih u klaonicama Fars (Shiraz, Južni Iran) u razdoblju od travnja 2006. do tavnja 2007. Ličinke kukca Oestrus ovis bile su dokazane u 261 (13,1%) životinje bez obzira na spol i dob. Ukupno je bilo sakupljeno 1356 ličinki. Prosječna jačina invazije iznosila je 5,2 ličinke s time da su prosječno 3,2 ličinke dokazane u proljeće, 3,8 ljeti, 4,6 u jesen i 6,8 ličinki zimi. Učestalost se kretala od 6,6% u proljeće do 17,9% zimi. Veća učestalost bila je dokazana u starijih životinja

First report of Polysarcus denticauda (Tettigoniidae: Phaneropterinae) from Iran and its bioacoustic characteristics

In 2013, during a bioacoustic investigation upon bushcrickets (Orthoptera, Ensifera) in Azarbaijan-e Sharghi, north-west of Iran, some ensiferans were collected in Azarshahr and identified as Polysarcus denticauda (Charpentier, 1825) (Tettigoniidae: Phaneropterinae). This is the first record of the species from Iran. Herewith, several diagnostic morphological and bioacoustic remarks are given

Comparison of chemical characteristics of shoot, root and litter in three range species of Salsola rigida, Artemisia sieberi and Stipa barbata

Some chemical characteristics of root, shoot and litter of index species such as Salsola rigida, Artemisia sieberi and Stipa barbata commonly used in rangeland development projects were evaluated and compared. Chemical properties of soil under and between the above mentioned species were also studied. For this purpose, vegetation types of Stipa barbata and Artemisia sieberi - Salsola rigida were selected in Zarand-eSaveh rangelands. Totally, 30 individuals of each species within each type were randomly selected for shoot, root and litter sampling and chemical analyses. Also, values of N, P, K, C and C/N ratio were measured in different parts of the species. Results showed that the highest and lowest C/N ratios were related to Stipa barbata root and Artemisia sieberi shoots, respectively. N and P values of Stipa barbata litter were the lowest while Artemisia sieberi and Salsola rigida shoots had the highest values of P and N, respectively. Litter of Salsola rigida and shoot of Artemisia sieberi had the lowest and highest K, respectively. C/N ratio of A. sieberi soil was lower than rest of the species

Cage culture of tilapia in some water resources (farm and agriculture ponds) of Bafq, Iran

Tilapia is the second cultured fish in the world. Up to 135 countries produces tilapia. Intensive culture systems of tilapia such as cage culture are recently developed because of limitations of water resources. In Iran, studies about tilapia were started in National Research Center of Saline Water Aquatics from November 2008 and some aspects of tilapia aquaculture and culture systems are surveyed. Investigation about cage culture of Nile tilapia, Oreochromis niloticus was performed in two culture periods of 2012 and 2014 in fresh and brackish water conditions of Iran for the first time. Stocking densities of fish in the cages were 25, 50, 75, 100, 125 and 150 fish/m^3. 100g fish stocked reached 272-331 g during 80 days in the first study. However, 50g fish stocked reached 329-450 g during 145 days in the second study. Results of cage culture of tilapia in fresh and brackish water conditions showed ranges of FCR: 1.56-3.72 and 1.08-1.87, DGR: 1.63-2.91 and 2.14-2.92 g/day, SGR: 0.63-1.12 and 1.29-1.54, production: 5.98-38 and 7.17-41.6 kg/m^3, respectively. Stocking densities 75-125 fish/ m^3 were appropriate especially in fish reared in brackish water cages