Vessel Category Research Articles

Factors affecting commercial trawl fleet landings in a multispecies fishery

Retained catches of trawl fleet in Chalkis fishing port-market, Greece, were analysed using generalized linear models (GLMs) in an attempt to identify factors that influence the total landings of the groundfish fisheries. Main effects in the model included a factor for vessel tonnage that determined fishing power, as well as factors for month and fishing area. Covariates examined were all found to have a significant effect on the retained catches, with month and vessel capacity alone explaining 38% and 30% respectively of the total variation of the data. Significant interactions observed indicate that the fluctuations in retained catch differed by fishing area and month as well as by fishing area and vessel category. Within vessel categories, month and fishing area also had significant effects on the retained catches, with fishing area being more important than month for the smallest vessels. Results indicate that the modelling approach of retained catches from trawl fisheries is a promising method for obtaining representative abundance indices.

Comparison of continuous and interrupted suture techniques in microvascular anastomosis

We evaluated the efficacy of the continuous suture technique (CST) in arteries and veins with varying external diameters (ED). In study 1 a direct end-to-end anastomosis was performed in 5 groups of animals (n = 15 in each group): group 1, rabbit carotid artery (ED, 1.8-2.0 mm); group 2, rabbit femoral artery (ED, 1.4-1.6 mm); group 3, rat femoral artery (ED, 0.7-0.9 mm); group 4, rabbit femoral vein (ED, 2.0-2.2 mm); and group 5, rat femoral vein (ED, 1.0-1.2 mm). In study 2 a graft from the femoral vein was interposed into the carotid artery, with a ratio of the diameter of graft to artery of 1.3:1 in the rats (group 6, n = 12) and 1:1 in the rabbits (group 7, n = 12). In each animal the vessel on one side was repaired using CST and the opposite vessel using the interrupted suture technique. Vessel samples were harvested 1, 2, and 4 weeks after anastomosis. The CST significantly reduced anastomosis time by up to 47% in arteries and 41% in veins. Bleeding time and blood loss were also significantly reduced with CST. Similar results were found in study 2. The total thrombosis rate was 8%, but no significant patency difference was noted between the CST and the interrupted suture technique in any vessel category. We conclude that the CST is a reliable and time-saving procedure in microvascular anastomosis of arteries with diameters greater than 0.7 mm and of veins with diameters greater than 1.0 mm.

Mathematical considerations for modeling cerebral blood flow autoregulation to systemic arterial pressure.

The shape of the autoregulation curve for cerebral blood flow (CBF) vs. pressure is depicted in a variety of ways to fit experimentally derived data. However, there is no general empirical description to reproduce CBF changes resulting from systemic arterial pressure variations that is consistent with the reported data. We analyzed previously reported experimental data used to construct autoregulation curves. To improve on existing portrayals of the fitting of the observed data, a compartmental model was developed for synthesis of the autoregulation curve. The resistive arterial and arteriolar network was simplified as an autoregulation device (ARD), which consists of four compartments in series controlling CBF. Each compartment consists of a group of identical vessels in parallel. The response of each vessel category to changes in perfusion pressure was simulated using reported experimental data. The CBF-pressure curve was calculated from the resistance of the ARD. The predicted autoregulation curve was consistent with reported experimental data. The lower and upper limits of autoregulation (LLA and ULA) were predicted as 69 and 153 mmHg, respectively. The average value of the slope of the CBF-pressure curve below LLA and beyond ULA was predicted as 1.3 and 3.3% change in CBF per mmHg, respectively. Our four-compartment ARD model, which simulated small arteries and arterioles, predicted an autoregulation function similar to experimental data with respect to the LLA, ULA, and average slopes of the autoregulation curve below LLA and above ULA.

海上ニアミス回避システムのための赤外画像からの船種の判別

海上ニアミス回避システムのための赤外画像からの船種の判別

Distribution of flow and red cell flux in the microcirculation

The distribution of blood cells in the vascular system is not homogeneous, red cell concentration in the small vessel compartment being significantly lower than in the large vessel compartment. This is to some extent due to the difference in travelling speed between cells and plasma in the microcirculation (Fahraeus effect). However, even in the terminal vessel network haematocrit varies considerably as a result of plasma skimming phenomena. Thus, local (capillary) haematocrit is a function of flow rate distribution at bifurcations. Red cell concentration in the majority of capillaries is substantially lower than in any other vessel category, while a small number of capillaries carry an increased haematocrit, thereby satisfying mass balance. The haematocrit distribution as well as the average level of capillary haematocrit is a function of small vessel volume which in turn depends on pre-capillary resistance: vasodilation leads to increased capillary haematocrit and vice versa. Thus, one of the physiological functions of the resistance vessels is to determine the level of microvascular haematocrit. Alteration of red cell microrheology leads to a reduction of capillary O2-transport capacity mainly by reducing the haematocrit in nutritive capillaries.

Effect of isoproterenol on the blood vessels of the spontaneously hypertensive rat

The reactivity of skeletal muscle arterioles to isoproterenol injections was compared in the normal control rat (NCR) and spontaneously hypertensive rat (SHR). The response to one second injections of 10 −8–10 −4g/ml of isoproterenol was dose dependent and of greatest magnitude in the vessel category with the smallest control diameter. SHR had lower threshold in small arteriolar vessels, but NCR exhibited greater maximum percent increase in vessel diameter.