Combinatorial formulation of Ising model revisited

In 1952, Kac and Ward developed a combinatorial formulation for the two dimensional Ising model which is another method of obtaining Onsager's formula for the free energy per site in the thermodynamic limit of the model. Feynman gave an important contribution to this formulation conjecturing a crucial mathematical relation which completed Kac and Ward ideas. In this paper, the method of Kac, Ward and Feynman for the free field Ising model in two dimensions is reviewed in a selfcontained way.Comment: 27 pages, 17 figure

Yang-Baxterization and the BH algebra.

The BH algebra is defined by two sets of generators one of which satisfy the relations of the braid group and the other the relations of the Hecke algebra of projectors. Both sets also satisfy additional relations having the Birman-Wenzl generating relations as a particular case.In this paper we consider the problem of finding solutions of the Yang-Baxter equation from representations of the BH algebra by the method of Yang-Baxterization of these representations

Efficiency of low versus high airline pressure in stunning cattle with a pneumatically powered penetrating captive bolt gun

The efficiency of stunning cattle was assessed in 443 animals (304 pure Zebu and 139 crossbred cattle), being mainly mature bulls and cows. Cattle were stunned using a Jarvis pneumatically powered penetrating captive bolt gun operating with low (160–175 psi, N = 82) and high (190 psi, N = 363) airline pressure, which was within the manufactures specifications. Signs of brain function and the position of the shots on the heads were recorded after stunning. Velocity of the captive bolt and its physical parameters were calculated. Cattle shot with low pressures showed more rhythmic respiration (27 vs. 8%, P < 0.001), less tongue protrusion (4 vs. 12%, P = 0.03) and less masseter relaxation (22 vs. 48%, P < 0.001). There was an increased frequency of shots in the ideal position when cattle were shot with the low compared to high airline pressures (15.3 vs. 3.1%). Bolt velocity and its physical parameters were significantly (P < 0.01) higher when using high pressure. Airline pressures below 190 psi are inappropriate when shooting adult Zebu beef cattle with pneumatically powered penetrating captive bolt guns

Seca do frutos do açaizeiro no estado do Pará.

Objetivou-se relatar a seca dos frutos do açaizeiro, em três diferentes municípios do estado do Pará, safra 2014. Amostras de frutos secos dos municípios de Abaetetuba e Belém foram analisadas no Laboratório de Fitopatologia da Embrapa Amazônia Oriental e do município de Igarapé Mirim no Laboratório de Microbiologia de Alimentos do IFPA - Campus Castanhal, respectivamente. Os frutos foram incubados em caixas do tipo 'gerbox' à temperatura de 25±2 ºC e fotoperíodo de 12h, durante até 72h. Procederam-se isolamentos diretos em placas de Petri com meio de cultura ágar-água a 20%. Frutos com esporulação do patógeno foram utilizados para o isolamento direto, sem incubação prévia, e analisados em microscópios estereoscópio e de luz. Após três dias de incubação, discos de micélios foram repicados para o meio de cultura batata dextrose ágar (BDA). Observaram-se crescimento micelial branco e, após 10 dias de incubação, verificou-se a formação de colônias de coloração acinzentada nas placas de Petri. Foram confeccionadas lâminas para microscopia de luz. Verificaram-se a presença de hifas septadas e ramificadas e intensa produção de conídios unicelulares hialinos, em ambas as amostras. A doença seca dos frutos foi confirmada em amostras oriundas dos municípios de Abaetetuba, Belém e Igarapé Mirim, com associação do fungo Colletotrichum spp