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Area Reduction (area + reduction)
Selected AbstractsImplications of different degrees of arytenoid cartilage abduction on equine upper airway characteristicsEQUINE VETERINARY JOURNAL, Issue 7 2008V. RAKESH Summary Reason for performing study: The necessary degree of arytenoid cartilage abduction (ACA) to restore airway patency at maximal exercise has not been determined. Objectives: Use computational fluid dynamics modelling to measure the effects of different degrees of ACA on upper airway characteristics of horses during exercise. Hypothesis: Maximal ACA by laryngoplasty is necessary to restore normal peak airflow and pressure in Thoroughbred racehorses with laryngeal hemiplegia. Methods: The upper airway was modeled with the left arytenoid in 3 different positions: maximal abduction; 88% cross-sectional area of the rima glottis; and 75% cross-sectional area of the rima glottis. The right arytenoid cartilage was maximally abducted. Two models were assumed: Model 1: no compensation of airway pressures; and Model 2: airway pressure compensation occurs to maintain peak airflow. The cross-sectional pressure and velocity distributions for turbulent flow were studied at peak flow and at different positions along the airway. Results: Model 1: In the absence of a change in driving pressure, 12 and 25% reductions in cross-sectional area of the larynx resulted in 4.11 and 5.65% reductions in peak airflow and 3.68 and 5.64% in tidal volume, respectively, with mild changes in wall pressure. Model 2: To maintain peak flow, a 6.27% increase in driving tracheal pressure was required to compensate for a cross-sectional reduction of 12% and a 13.63% increase in driving tracheal pressure was needed for a cross-sectional area reduction of 25%. This increase in negative driving pressure resulted in regions with low intraluminal and wall pressures, depending on the degree of airway diameter reduction. Conclusion: Assuming no increase in driving pressure, the decrease in left ACA reduced airflow and tidal volume. With increasing driving pressure, a decrease in left ACA changed the wall pressure profile, subjecting the submaximally abducted arytenoid cartilage and adjacent areas to airway collapse. Clinical relevance: The surgical target of ACA resulting in 88% of maximal cross-sectional area seems to be appropriate. [source] Wing wear, aerodynamics and flight energetics in bumblebees (Bombus terrestris): an experimental studyFUNCTIONAL ECOLOGY, Issue 4 2001A. Hedenström Summary 1,Previous work has shown that wing wear increases mortality rate in bumblebees. Two proximate explanations have been suggested to account for this: increased energy flight costs and increased predation risk due to reduced manoeuvrability. 2,Wing wear was mimicked by experimentally clipping the forewing distal trailing edge, causing a 10% wing area reduction. Experimental and sham control bumblebees were induced to hover in a flight respirometry chamber for measuring metabolic rate of hovering. Simultaneous video and sound recordings were taken for wingbeat kinematic data required for an aerodynamic analysis. 3,In the experimental group with reduced wing area we measured increased wingbeat frequency, lift coefficient and induced power, but a reduced profile power. The mechanical power output, assuming perfect elastic storage in the flight system, remained largely unchanged after the wing-trimming treatment. 4,Metabolic flight costs (CO2 production rate) did not increase significantly in the reduced wing area group, which is in line with the aerodynamic power output. 5,Our results indicate that an increase of flight cost due to wing wear is not a likely explanation for increased mortality rate in bumblebees. Wing wear may, however, affect escape performance from predators. [source] Increased leaf area dominates carbon flux response to elevated CO2 in stands of Populus deltoides (Bartr.)GLOBAL CHANGE BIOLOGY, Issue 5 2005Ramesh Murthy Abstract We examined the effects of atmospheric vapor pressure deficit (VPD) and soil moisture stress (SMS) on leaf- and stand-level CO2 exchange in model 3-year-old coppiced cottonwood (Populus deltoides Bartr.) plantations using the large-scale, controlled environments of the Biosphere 2 Laboratory. A short-term experiment was imposed on top of continuing, long-term CO2 treatments (43 and 120 Pa), at the end of the growing season. For the experiment, the plantations were exposed for 6,14 days to low and high VPD (0.6 and 2.5 kPa) at low and high volumetric soil moisture contents (25,39%). When system gross CO2 assimilation was corrected for leaf area, system net CO2 exchange (SNCE), integrated daily SNCE, and system respiration increased in response to elevated CO2. The increases were mainly as a result of the larger leaf area developed during growth at high CO2, before the short-term experiment; the observed decline in responses to SMS and high VPD treatments was partly because of leaf area reduction. Elevated CO2 ameliorated the gas exchange consequences of water stress at the stand level, in all treatments. The initial slope of light response curves of stand photosynthesis (efficiency of light use by the stand) increased in response to elevated CO2 under all treatments. Leaf-level net CO2 assimilation rate and apparent quantum efficiency were consistently higher, and stomatal conductance and transpiration were significantly lower, under high CO2 in all soil moisture and VPD combinations (except for conductance and transpiration in high soil moisture, low VPD). Comparisons of leaf- and stand-level gross CO2 exchange indicated that the limitation of assimilation because of canopy light environment (in well-irrigated stands; ratio of leaf : stand=3.2,3.5) switched to a predominantly individual leaf limitation (because of stomatal closure) in response to water stress (leaf : stand=0.8,1.3). These observations enabled a good prediction of whole stand assimilation from leaf-level data under water-stressed conditions; the predictive ability was less under well-watered conditions. The data also demonstrated the need for a better understanding of the relationship between leaf water potential, leaf abscission, and stand LAI. [source] Evaluation of the nano-oligosaccharide factor lipido-colloid matrix in the local management of venous leg ulcers: results of a randomised, controlled trialINTERNATIONAL WOUND JOURNAL, Issue 2 2008Jean-Luc Schmutz Abstract The nano-oligosaccharide factor (NOSF) is a new compound aiming to promote wound closure mainly through inhibition of matrix metalloproteinase (MMP) activity. This factor is incorporated within a lipido-colloid matrix (Techonology Lipido-Colloid-NOSF matrix) and locally released in the wound. The objective of this study was to document the performance (non inferiority or superiority) of the NOSF relative to the Promogran® matrix (oxidised regenerated cellulose, ORC) effect in the local management of venous leg ulcers (VLUs). This was a 12-week, open, two-arm, multicentre, randomised study. Patients were selected if the area of their VLU [ankle brachial pressure index ,0·80] ranged from 5 to 25 cm2 with a duration ,3 months. Ulcers had to be free from necrotic tissue. In addition to receiving compression bandage therapy, patients were randomly allocated to either NOSF matrix or ORC treatment for 12 weeks. The VLUs were assessed on a weekly basis and wound tracings were recorded. Percentage wound relative reduction (%RR) was the primary efficacy criterion. Secondary objectives were wound absolute reduction (AR), healing rate (HR) and % of wounds with ,40% reduction compared with baseline. A total of 117 patients were included (57 NOSF matrix and 60 ORC). Mean population age was 71·3 ± 13·5 years, body mass index was ,30 kg/m2 in 39·3% and 15·4% were diabetics. Fifty-six per cent of the VLUs were present for >6 months, 61% were recurrent and 68% were stagnating despite appropriate care. Mean wound area at baseline was 11·2 ± 7·4 cm2. At the last evaluation, mean difference between the groups for %RR was 33·6 ± 15·0% in favour of NOSF matrix with a unilateral 95% confidence interval (CI) lower limit of 8·6% not including the null value. Therefore, a superiority of NOSF matrix effect compared with ORC was concluded (P = 0·0059 for superiority test). The median of the wound area reduction was 61·1% and 7·7% in the NOSF matrix and control groups, respectively (per-protocol analysis), or 54·4% versus 12·9% in intent-to-treat analysis (p = 0·0286). Median AR was 4·2 cm2 in the NOSF group and 1·0 cm2 with ORC (P = 0·01). Median HR was ,0·056 and ,0·015 cm2/day in NOSF and ORC groups, respectively (P = 0·029). By logistic regression, the NOSF versus control odds ratio to reach 40% area reduction was 2·4 (95% CI: 1·1,5·3; P = 0·026). In the oldest and largest VLUs, a strong promotion of healing effect was particularly observed in the NOSF matrix group compared with the control group. NOSF matrix is a very promising option for the local management of chronic wounds, especially for VLUs with poor healing prognosis. [source] Design of meander square-ring resonator and its application in RF power dividerMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2009Fei Zhang Abstract First, this letter presents a novel meander square-ring resonator (MSRR) and its stop-band and slow-wave effects are investigated. Served by the proposed MSRR, unwanted higher-order 2nd and 3rd harmonics of power divider are effectively rejected benefiting from its stop-band effect without any additional filter, and the physical length of quarter-wavelength 70.7 ohm microstrip in power divider is halved utilizing its slow-wave effect without decreasing the electrical length. Finally, power divider with area reduction by 42.6% is successfully obtained, compared with conventional design. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1602,1604, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24394 [source] Placental insulin-like growth factor II (IGF-II) and its relation to litter size in the common marmoset monkey (Callithrix jacchus)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 12 2009Julienne N. Rutherford Abstract The primate placenta produces a wide variety of hormones throughout gestation that regulate placental function and fetal growth. One such hormone is insulin-like growth factor-II (IGF-II), a peptide implicated in cell division, differentiation, and amino acid transport. IGF-II concentrations were measured in 23 common marmoset (Callithrix jacchus) term placentas from twin and triplet litters in order to determine whether previously described differences in fetoplacental phenotype such as placental and litter mass and placental surface area were related to differences in endocrine function. IGF-II was extracted from frozen tissue samples and measured using an enzyme-linked immunosorbent assay kit designed for human tissue, which was validated for marmoset placenta. IGF-II concentrations were not related to placental or litter mass, and twin and triplet placentas did not differ in total concentration. However, per individual fetus, triplets were associated with a significant 42% reduction in IGF-II concentration (P=0.03), and IGF-II concentration per gram of fetal mass was a third lower in triplet litters. The triplet placenta exhibits a global expansion of the surface area which was contrasted by a per unit area reduction in IGF-II concentration (r=,0.75, P=0.01), a pattern that explains why twin and triplet placentas overall did not differ in concentration. Per fetus, triplet pregnancies are associated with relatively less maternal mass, placental mass and microscopic surface area suggesting that the intrauterine growth of triplets is supported by systems that increase the efficiency of nutrient transfer. The finding that individual triplet fetuses are also associated with significantly lower IGF-II concentrations is consistent with the view that the marmoset fetoplacental unit exhibits a flexible pattern of placental allocation and metabolism. Plasticity in placental endocrine and metabolic function is likely to play an important role in the ability of the fetus to sense and accommodate the intrauterine environment and, by extension, the external ecology. Am. J. Primatol. 71:969,975, 2009. © 2009 Wiley-Liss, Inc. [source] Effects of Supplementation with Ascorbic Acid for a Period of 120 days on the Myosin-V and NADPHd Positive Myenteric Neurons of the Ileum of RatsANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 3 2005J. N. Zanoni Summary We investigated the effect of ascorbic acid (AA) supplementation on the NADPH-diaphorase (NADPHd) and myosin-V myenteric neurons in the ileum of rats, after 4 months of treatment. Two groups were compared, i.e. controls rats (C) and AA-treated rats (CA). Myosin-V immunohistochemistry and NADPHd histochemistry were employed. We investigated the areas of 500 cell bodies of myosin-V neurons and of 500 NADPHd stained neurons from all groups. The quantitative analysis was performed using an area of 8.96 mm2 from each ileum. There was an increase of 21.9% in the myosin-V immunoreactive myenteric neurons (P > 0.05) and of 22.5% in the NADPHd in group CA when compared with C (P < 0.05). There were no significant differences when we compared the area of myosin-V stained neurons between groups C and CA. However, we verified an area reduction of 7.5% in NADPHd neurons when comparing group C to group CA (P < 0.05). [source] | |||||||||||||