The Finite Temperature SU(2) Savvidy Model with a Non-trivial Polyakov Loop

We calculate the complete one-loop effective potential for SU(2) gauge bosons at temperature T as a function of two variables: phi, the angle associated with a non-trivial Polyakov loop, and H, a constant background chromomagnetic field. Using techniques broadly applicable to finite temperature field theories, we develop both low and high temperature expansions. At low temperatures, the real part of the effective potential V_R indicates a rich phase structure, with a discontinuous alternation between confined (phi=pi) and deconfined phases (phi=0). The background field H moves slowly upward from its zero-temperature value as T increases, in such a way that sqrt(gH)/(pi T) is approximately an integer. Beyond a certain temperature on the order of sqrt(gH), the deconfined phase is always preferred. At high temperatures, where asymptotic freedom applies, the deconfined phase phi=0 is always preferred, and sqrt(gH) is of order g^2(T)T. The imaginary part of the effective potential is non-zero at the global minimum of V_R for all temperatures. A non-perturbative magnetic screening mass of the form M_m = cg^2(T)T with a sufficiently large coefficient c removes this instability at high temperature, leading to a stable high-temperature phase with phi=0 and H=0, characteristic of a weakly-interacting gas of gauge particles. The value of M_m obtained is comparable with lattice estimates.Comment: 28 pages, 5 eps figures; RevTeX 3 with graphic

Associação do methimazole e do ondansetron à quimioterapia com cisplatina em cães submetidos a quatro diferentes protocolos de fluidoterapia Association of methimazole and ondansetron to cisplatin chemotherapy in dogs submitted to four different fluid therapy protocols

Utilizaram-se 12 cães, machos, distribuídos em quatro grupos (G) experimentais, selecionados de acordo com o tempo de fluidoterapia com solução fisiológica 0,9%: G1 (sem fluidoterapia), G2 (uma hora de fluidoterapia antes da cisplatina), G3 (uma hora de fluidoterapia antes da cisplatina e uma hora após) e G4 (duas horas de fluidoterapia antes da cisplatina e uma após). Todos os animais receberam a cisplatina (70mg/m²), pela via intravenosa, sendo os ciclos de quimioterapia realizados em intervalos de três semanas, num total de três ciclos. O ondansetron (0,4mg/kg) foi administrado pela via intravenosa, a cada oito horas, no dia da quimioterapia e, a seguir, a cada 12 horas, por dois dias. O methimazole (40mg/kg) foi pela via oral, 30 minutos antes da cisplatina e quatro horas após. Avaliaram-se os parâmetros hematológicos, bioquímicos, urinários e dosagem de tiroxina e triiodotironina a cada sete dias até o término do experimento. Esse protocolo foi eficaz e seguro em cães que permaneceram sob fluidoterapia durante duas a três horas. Os animais que não receberam fluidoterapia e os que ficaram somente uma hora sob infusão intravenosa de solução fisiológica apresentaram alterações que resultaram em não-recomendação do protocolo.<br>Twelve male dogs were divided in four experimental groups (G), which were selected according to the time of 0.9% saline fluid therapy: G1 (without saline therapy), G2 (an hour of saline therapy before receiving cisplatin), G3 (an hour of saline therapy before receiving cisplatin and one hour after) and G4 (two hours of saline therapy before receiving cisplatin and one hour after). All the animals received 70mg/m² cisplatin, via intravenous, and the chemotherapy cycles were accomplished in intervals of three weeks, in a total of three cycles. Ondansetron (0.4mg/kg) was administered via intravenous, every 8 hours, on the day of the chemotherapy and, from that, every 12 hours for two days. Methimazole (40mg/kg) was orally administered 30 minutes before the cisplatin injection and four hours after. The hematological, biochemical and urinary parameters and dosages of tiroxin and triiodotironine were evaluated every seven days until the end of the experiment. This protocol was effective and safe in the animals that stayed for a period of two or three hours receiving saline therapy, because they did not present clinical and laboratory alterations of the use of chemotherapy. The animals that did not receive saline therapy and those that received infusion of physiologic solution via IV only during one hour presented alterations that made unfeasible the use of this protocol