Lactate sequestration by osteoderms of the broad-nose caiman, Caiman latirostris, following capture and forced submergence

Lactate accumulation in osteoderms; of the broad-nose caiman, Caiman latirostris, was determined following capture and surgery and after a period of forced submergence and related to concurrent values in blood. Control samples of bone and blood were taken after recovery from surgery and before submergence. In addition, samples of osteoderm were incubated in a lactate solution to determine equilibrium concentration, and additional samples were analyzed for elemental and CO2 concentrations. The composition of the osteoderms closely resembles that of typical vertebrate bone, with a high concentration of calcium and phosphate. Plasma and osteoderm lactate concentrations were both elevated following surgery and decreased significantly after 1 day of recovery. Submergence produced a typical lactate pattern in the plasma, with only a modest increase during the dive and then a sharp increase during recovery to a peak of 31.2 +/- 1.9 mumol ml(-1) after 1 h. When caimans were anesthetized 2 h after submergence, osteoderm lactate in the same animals was significantly increased to 14.8 mumol g(-1) wet mass. The ratio of the osteoderm: plasma lactate concentration after submergence was similar to the ratio observed in the incubated samples, suggesting that osteoderm lactate concentrations in vivo were equilibrated with circulating plasma levels. We conclude that caiman osteoderms sequester lactate during lactic acidosis and that the time course is fast enough to have benefit to these animals following normal anaerobic burst activity.

Performance of layers submitted to different forced-molting methods and different temperatures

This study was carried out to evaluate the performance and egg quality of laying hens, in their second laying cycle submitted to different forced-molting methods and three environmental temperatures. Six hundred layers were distributed in a completely randomized experimental design with 15 treatments with five replicates of eight birds each, according to 5x3 factorial arrangement (molting methods vs. temperatures). The following forced-molting methods were applied: 90%, 70%, 50% dietary alfalfa inclusion, addition of 2,800 ppm zinc, and feed fasting. Temperatures were: 20 ºC, 27 ºC and 35 ºC. At the end of each period of the second laying cycle, bird performance and egg quality were evaluated. Data were submitted to analysis of variance and means were compared by orthogonal and polynomial contrasts. The highest alfalfa inclusion level (90% alfalfa and 10% basal diet) proved to be efficient as compared to the other methods, independently of temperature.

Analysis of cardiovascular system responses to forced vital capacity in COPD

CONTEXTUALIZAÇÃO: O teste de capacidade vital forçada (CVF) é rotineiramente realizado na avaliação da função pulmonar de pacientes com doença pulmonar obstrutiva crônica (DPOC). Entretanto, permanece pouco compreendida a influência do teste de CVF sobre o sistema cardiovascular de pacientes com DPOC. OBJETIVOS: Analisar o comportamento da frequência cardíaca (FC), pressão arterial (PA) e variabilidade da frequência cardíaca (VFC) no teste de CVF na DPOC. MÉTODOS: Dezenove homens com DPOC (72 ± 7 anos, no estágio de gravidade GOLD I=3, II=5, III=7 e IV=4 pacientes) realizaram a manobra de CVF e tiveram sua FC monitorada durante todo o exame, e a VFC analisada nos domínios do tempo (rMSSD) e da frequência (BF, AF e BF/AF) durante o repouso, antes e após a melhor manobra de CVF. A PA foi analisada no repouso, imediatamente ao final da manobra de CVF e 10 minutos após o término de todos os testes. RESULTADOS: Ao início da manobra de CVF, a FC reduziu (p<0,001) e, em seguida, aumentou progressivamente até o final do teste (p<0,001). Após término da manobra, a FC continuou a aumentar até atingir um pico (p<0,001) e depois caiu rapidamente a valores inferiores aos de repouso (p<0,001) e retornou ao seu valor basal. A PA e os índices da VFC não sofreram alterações nos períodos analisados. CONCLUSÃO: O teste de CVF influencia o comportamento da FC, sem alterar o seu controle autonômico, bem como a PA em pacientes com DPOC nos períodos analisados.

Time reduction in a forced-convection thermal process using simplified transient analysis

This study investigates the utilisation of a simplified model in the transient analysis of a thermal cooling process. In such process the external thermal resistance between the surface and the surroundings is high compared to the system internal thermal resistance, so that the first controls the heat transfer process. In this case the Biot number is lower than 0.1. Aluminium reels were utilised, which, with proper internal instrumentation, furnished experimental results for the thermal cooling process. Based on experimental data, a simplified model for the determination of the process film coefficient was used. Subsequently, experimental and theoretical results were compared. The change of the airflow direction was also investigated for the cooling process, aiming at process time optimisation. (C) 2001 Elsevier B.V. Ltd.

Forced-Molting methods and their effects on the performance and egg quality of japanese quails (Coturnix japonica) in the second laying cycle

The experiment was carried out in the experimental poultry house of the Research and Development Unit of Brotas of Agência Paulista de Tecnologia dos Agronegócios do Centro-Oeste, SP, Brazil. The objective of the study was to evaluate the performance of Japanese quails submitted to forced molting aiming at optimizing the use of the same quail flock by promoting a second laying cycle. A total number of 400 67-day-old Japanese quails in lay, previously submitted to 14 days of forced molting, was distributed in a completely randomized experimental design into five treatments (T1= not submitted to forced molting, T2= 03 days of fasting + fed ad libitum, T3= 01 days of fasting + 13 days of feed restriction, T4= 02 days of fasting + 12 days of feed restriction, and T5= 03 days of fasting + 11 days of feed restriction. Feeds were contained equal nutrient levels, and were formulated according to NRC (1994) recommendations. There were significant differences among the studied treatments. Although the treatment of 3 days of fasting followed by ad libitum feeding resulted in lower egg weight, it promoted better lay percentage, egg mass, and feed conversion ratios (FCR/dz and FCR/kg). on the other hand, 3 days of fasting followed by restricted feeding resulted in higher feed intake and worse feed conversion ratios (FCR/dz and FCR/kg). When birds were not submitted to forced molting, they presented lower lay percentage and egg mass.

The effects of alternative forced-molting methods on the performance and egg quality of commercial layers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Autonomic control of heart rate during forced activity and digestion in the snake Boa constrictor

Reptiles, particularly snakes, exhibit large and quantitatively similar increments in metabolic rate during muscular exercise and following a meal, when they are apparently inactive. The cardiovascular responses are similar during these two states, but the underlying autonomic control of the heart remains unknown. We describe both adrenergic and cholinergic tonus on the heart during rest, during enforced activity and during digestion (24-36h after ingestion of 30% of their body mass) in the snake Boa constrictor. The snakes were equipped with an arterial catheter for measurements of blood pressure and heart rate, and autonomic tonus was determined following infusion of the beta -adrenergic antagonist propranolol (3mg kg(-1)) and the muscarinic cholinoceptor antagonist atropine (3 mg kg-1).The mean heart rate of fasting animals at rest was 26.4 +/- 1.4 min(-1), and this increased to 36.1 +/- 1.4 min(-1) (means +/- S.E.M.; N=8) following double autonomic block (atropine and propranolol). The calculated cholinergic and adrenergic tones were 60.1 +/- 0.3% and 19.8 +/- 2.2%, respectively. Heart rate increased to 61.4 +/- 1.5 min(-1) during enforced activity, and this response was significantly reduced by propranolol (maximum values of 35.8 +/-1.6 min(-1)), but unaffected by atropine. The cholinergic and adrenergic tones were 2.6 +/- 2.2 and 41.3 +/- 1.9 % during activity, respectively. Double autonomic block virtually abolished tachycardia associated with enforced activity (heart rate increased significantly from 36.1 +/- 1.4 to 37.6 +/- 1.3 min(-1)), indicating that non-adrenergic, non-cholinergic effectors are not involved in regulating heart rate during activity. Blood pressure also increased during activity.Digestion was accompanied by an increase in heart rate from 25.6 +/- 1.3 to 47.7 +/- 2.2 min(-1) (N=8). In these animals, heart rate decreased to 44.2 +/- 2.7 min-1 following propranolol infusion and increased to 53.9 +/- 1.8 min-1 after infusion of atropine, resulting in small cholinergic and adrenergic tones (6.0 +/- 3.5 and 11.1 +/- 1.1 %, respectively). The heart rate of digesting snakes was 47.0 +/- 1.0 min(-1) after double autonomic blockade, which is significantly higher than the value of 36.1 1.4 min-1 in double-blocked fasting animals at rest. Therefore, it appears that some other factor exerts a positive chronotropic effect during digestion, and we propose that this factor may be a circulating regulatory peptide, possibly liberated from the gastrointestinal system in response to the presence of food.

SINGULARITY THEORY and FORCED SYMMETRY BREAKING IN EQUATIONS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Loss of superfluidity in a Bose-Einstein condensate via forced resonant oscillations

We predict the loss of superfluidity in a Bose-Einstein condensate in an axially symmetric harmonic trap alone during resonant collective oscillations via a classical dynamical transition. The forced resonant oscillation can be initiated by (a) periodic modulation of the atomic scattering length with a frequency that equals twice the radial trapping frequency or multiples thereof, or by (b) periodic modulation of the radial trapping potential with a frequency that equals the radial trapping frequency or multiples thereof. Suggestion for future experiment is made. (C) 2003 Elsevier B.V. B.V. All rights reserved.

Influence of gender and estrous cycle in the forced swim test in rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fertility of male adult rats submitted to forced swimming stress

We investigated whether stress interferes with fertility during adulthood. Male Wistar rats (weighing 220 g in the beginning of the experiment) were forced to swim for 3 min in water at 32ºC daily for 15 days. Stress was assessed by the hot-plate test after the last stressing session. To assess fertility, control and stressed males (N = 15 per group) were mated with sexually mature normal females. Males were sacrificed after copulation. Stress caused by forced swimming was demonstrated by a significant increase in the latency of the pain response in the hot-plate test (14.6 ± 1.25 s for control males vs 26.0 ± 1.53 s for stressed males, P = 0.0004). No changes were observed in body weight, testicular weight, seminal vesicle weight, ventral prostate weight or gross histological features of the testes of stressed males. Similarly, no changes were observed in fertility rate, measured by counting live fetuses in the uterus of normal females mated with control and stressed males; no dead or incompletely developed fetuses were observed in the uterus of either group. In contrast, there was a statistically significant decrease in spermatid production demonstrated by histometric evaluation (154.96 ± 5.41 vs 127.02 ± 3.95 spermatids per tubular section for control and stressed rats, respectively, P = 0.001). These data demonstrate that 15 days of forced swimming stress applied to adult male rats did not impair fertility, but significantly decreased spermatid production. This suggests that the effect of stress on fertility should not be assessed before at least the time required for one cycle of spermatogenesis.

Female monopolization and paternity assurance in South American crickets (Orthoptera, Grylloidea): mating plugs, extra claspers and forced copulation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Forced convection to laminar flow of liquid egg yolk in circular and annular ducts

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

D-n-forced symmetry breaking of O(2)-equivariant problems

We use singularity theory to classify forced symmetry-breaking bifurcation problemsf(z, lambda, mu) = f(1)(z, lambda) + muf(2)(z, lambda, mu) = 0,where f(1) is O(2)-equivariant and f(2) is D-n-equivariant with the orthogonal group actions on z is an element of R-2. Forced symmetry breaking occurs when the symmetry of the equation changes when parameters are varied. We explicitly apply our results to the branching of subharmonic solutions in a model periodic perturbation of an autonomous equation and sketch further applications.