Higher Mean Growth Rate Research Articles

Influence of a Static Magnetic Field on the ⟨100⟩ Growth Rates of Sodium Chlorate Crystals from Aqueous Solution.

The results of the study of the influence of a static magnetic field of 55 ± 3 mT on the growth rates of diamagnetic sodium chlorate crystals in the direction ⟨100⟩ will be presented. Two groups of experiments were performed in the same solution supersaturation range of 0.89-1.78%, the first in zero field conditions, and the second in an applied magnetic field. The results show that crystals nucleated and grown in a static magnetic field have higher mean growth rates in the ⟨100⟩ direction than crystals in a zero field. Also, X-ray analyses suggest that crystals nucleated and grown in a magnetic field may have a higher lattice constant. Possible mechanisms and possible reasons for these phenomena are discussed.

Abstract TP386: Growing Intracranial Aneurysms in Older Patients Tend to Have Higher Annual Growth Rates

Introduction: Numerous previous studies have discussed the correlation between patient age and aneurysm rupture. However, the existing base of knowledge regarding the relationship between patient age and aneurysm growth, specifically growth rate, is significantly smaller. The objective of this study is to examine the correlation between patient age and aneurysm growth in order to help devise better clinical management strategies. Hypothesis: Growing aneurysms in older patients will exhibit a higher mean growth rate relative to those in younger patients. Methods: In this study, the records of 361 patients between the age of 40 and 97 at the time of initial diagnosis with unruptured intracranial aneurysms in the UCLA Medical Center between January 2005 and December 2015 were reviewed. These patients were continuously followed using CTA neurovascular imaging, ending when the patient either received surgical or endovascular treatment or discontinued follow-up visits. Results: A total of 496 UIA in the 361 patients were classified into four groups by patient age (40-49, n=56; 50-59, n=120; 60-69, n=145; 70+, n=175). Incidence of growth was 14.29%, 11.67%, 8.28%, and 12.57% for the 40-49, 50-59, 60-69, and 70+ groups, respectively. Growth rates were 0.30±0.12, 0.58±0.42, 0.90±0.72, and 0.78±0.75 mm/yr for the 40-49, 50-59, 60-69, and 70+ groups, respectively. Differences in growth rates were not significant between the four groups (ANOVA, p=0.15). However, when patients were divided by age 50 years, growth rates were significantly higher in the 50+ group (p<0.05). Conclusion: Although there was a high level of variation in growth rate between individual cases, this study found that patients with growing aneurysms over the age of 50 are at a higher risk for rapid aneurysm growth compared to younger patients, a finding that may prove helpful in developing clinical management protocols.

Drought Response in Selected Tropical Inbred Maize Lines and Relative Expression of <i>PARP2</i> Gene under Limited Water Conditions

Drought is the leading single factor that limits maize production thus inhibiting the crops genetic potential. In response to drought, maize and other plants synthesize Poly ADP-Ribose (PAR) protein. This process is controlled by the Poly ADP-Ribose Polymerase (PARP) genes and consumes cellular energy, leading to plant death. This study evaluated four tropical inbred maize (<i>Zea mays L</i>.) lines; CML 216, CML 144, A04 and E04 for their response to growth limiting water stress and their relative expression of <i>PARP2</i> gene under drought and non-drought conditions. The leaf lengths and growth rates of the fourth leaf were monitored for 21days post emergence while fresh and dry weights of drought stressed and non-stressed seedlings were recorded a month after emergence of the fourth leaf. The relative expression of <i>PARP2</i> gene was determined using rtPCR after isolating RNA from drought stressed and non-stressed maize seedlings. There was no significant difference in the mature lengths of the fourth leaf in the four genotypes when the maize seedlings were not subjected to drought and when subjected to severe drought stress. However, subjecting maize seedlings to mild drought resulted in a significant difference in the mature leaf lengths based on the different genotypes (P= 0.0066). The growth rate of maize seedlings based on the fourth leaf was observed to be affected by drought, with a higher mean growth rate (1.74 cm day^-1) registered in seedlings which were not subjected to drought and those subjected to moderate drought (1.78 cm day^-1). A slower growth rate (1.37 cm day^-1) was observed in seedlings subjected to severe drought stress. Fresh and dry weights of maize seedlings were also observed to be significantly different based on the level of drought exerted (P = < 0.0001) and the genotype (P = < 0.0001). The expression of <i>PARP2</i> gene was found to be directly proportional to the level of drought stress exerted. Results from this study suggest how tropical maize genotypes respond to drought.

Prothonotary warbler nestling growth and condition in response to variation in aquatic and terrestrial prey availability.

Aquatic prey subsidies entering terrestrial habitats are well documented, but little is known about the degree to which these resources provide fitness benefits to riparian consumers. Riparian species take advantage of seasonal pulses of both terrestrial and aquatic prey, although aquatic resources are often overlooked in studies of how diet influences the reproductive ecology of these organisms. Ideally, the timing of resource pulses should occur at the time of highest reproductive demand. This study investigates the availability of aquatic (mayfly) and terrestrial (caterpillar) prey resources as well as the nestling diet of the prothonotary warbler (Protonotaria citrea) at two sites along the lower James River in Virginia during the 2014 breeding season. We found large differences in availability of prey items between the two sites, with one having significantly higher mayfly availability. Nestling diet was generally reflective of prey availability, and nestlings had faster mean growth rates at the site with higher aquatic prey availability. Terrestrial prey were fed more readily at the site with lower aquatic prey availability, and at this site, nestlings fed mayflies had higher mean growth rates than nestlings fed only terrestrial prey. Our results suggest that aquatic subsidies are an important resource for nestling birds and are crucial to understanding the breeding ecology of riparian species.

Effect of housing density on growth, agonistic behaviour, and activity in hatchling saltwater crocodiles (Crocodylus porosus)

The purpose of this study was to examine the effect of density on growth rate, agonistic behaviour, activity and use of space by hatchling C. porosus in captivity. Hatchling C. porosus were raised in identical enclosures (1.5m2) at different densities (3.3, 6.7, 13.3 and 20.0hatchlings/m2; or 0.30, 0.15, 0.08 and 0.05m2/hatchling respectively). Hatchlings came from 5 different clutches, hatched on the same day, spread evenly between density treatments (2 replicates per treatment). Growth rate (grams per day) was assessed between 4 and 25days of age, which is a reliable indicator of post-hatching growth trajectories for this species. Clutch and initial body mass (BM) had a strong influence on growth rate, with a lower growth rate among the largest hatchlings born. The highest mean growth rate in body mass occurred at 6.7/m2 (6.12±1.24g/d) and was lowest at the highest density (20.0/m2: −2.33±0.63g/d). Behavioural observations taken every 10min on day 19 (24h period) confirmed that hatchlings remained relatively inactive and hidden under cover for most of the day, and were more active at night, with peaks at dusk and dawn. However, the level of hourly activity (mean movements per individual per hour) was highest at densities of 13.3/m2 and 20.0/m2, compared with densities of 3.3/m2 and 6.7/m2. Behavioural observations at 17:00–8:00h over 3days (days 17–19) revealed that the frequency of agonistic interactions (mean per animal per night) was highest at the lower densities (3.3/m2; 6.7/m2) and decreased with increased density (13.3/m2; 20.0/m2). The results suggest that as density increases above 6.7/m2, growth rate in hatchling C. porosus during the first 3 weeks begins to decline as activity increases. However, at the lowest density (and group size: 5), 1 or 2 individuals become dominant and grow large at the expense of the remaining hatchlings. Based on these results, it appears that the high and low densities tested may have an adverse effect on hatchling C. porosus growth rate and behaviour in captivity.

English

Cyanobacteria are a cheap source of nitrogen and quite suitable for farmers of developing countries. Although, they live in a diverse range of environments, different environmental variables influence their nitrogen fixing ability. Thus, this study evaluated the effect of pond depth and lining plastic colors on nitrogen fixing capacity of Anabaena species strain E3. Factorial combinations of four pond lining plastic colors and two depths were laid out in a complete randomized design with three replications. The ANOVA results revealed that the 20 cm depth pond had a higher mean growth rate (0.063 OD day -1 ), dissolved oxygen (17.63 mg L -1 ), dry biomass (0.58 g L -1 ) and total nitrogen (27.77 mg L -1 ) than the 40 cm depth. The highest mean growth rate (0.089 OD day -1 ), dissolved oxygen (19.07 mg L -1 ), dry biomass (0.66 g L -1 ) and total nitrogen (41.60 mg L -1 ) were registered in the treatment with a transparent lining plastic color. Moreover, it was noted that, the test strain under the treatment combinations of 20 cm depth and transparent plastic lining expressed the highest mean optical density (1.227), heterocyst frequency (2.92%) and pH (10.28). Therefore, for mass-production of E3-strain-based biofertilizer, the strain should be grown in ponds of 20 cm depth with transparent plastic. Keywords: Cyanobacteria, dry biomass, growth rate, shallow pond, total nitrogen

Climatology of new particle formation at Izaña mountain GAW observatory in the subtropical North Atlantic

Abstract. A climatology of new particle formation (NPF) events at high altitude in the subtropical North Atlantic is presented. A 4-year data set (June 2008–June 2012), which includes number size distributions (10–600 nm), reactive gases (SO2, NOx, and O3), several components of solar radiation and meteorological parameters, measured at Izaña Global Atmosphere Watch (GAW) observatory (2373 m above sea level; Tenerife, Canary Islands) was analysed. NPF is associated with the transport of gaseous precursors from the boundary layer by orographic buoyant upward flows that perturb the low free troposphere during daytime. On average, 30% of the days contained an NPF event. Mean values of the formation and growth rates during the study period were 0.46 cm−3 s−1 and 0.42 nm h−1, correspondingly. There is a clearly marked NPF season (May–August), when these events account for 50–60% of the days per month. Monthly mean values of the formation and growth rates exhibit higher values in this season, 0.49–0.92 cm−3 s−1 and 0.48–0.58 nm h−1, respectively. During NPF events, SO2, UV radiation and upslope winds showed higher values than during non-events. The overall data set indicates that SO2 plays a key role as precursor, although other species seem to contribute during some periods. Condensation of sulfuric acid vapour accounts for most of the measured particle growth during most of the year (~70%), except for some periods. In May, the highest mean growth rates (~0.6 nm h−1) and the lowest contribution of sulfuric acid (~13%) were measured, suggesting a significant involvement of other condensing vapours. The SO2 availability seems also to be the most influencing parameter in the year-to-year variability in the frequency of NPF events. The condensation sink showed similar features to other mountain sites, showing high values during NPF events. Summertime observations, when Izaña is within the Saharan Air Layer, suggest that dust particles may play a significant role acting as coagulation sink of freshly formed nucleation particles. The contribution of dust particles to the condensation sink of sulfuric acid vapours seems to be modest (~8% as average). Finally, we identified a set of NPF events in which two nucleation modes, which may evolve at different rates, occur simultaneously and for which further investigations are necessary.

Demographics and Parasitism of American Eels in the Chesapeake Bay, USA

AbstractThe Chesapeake Bay supports the largest U.S. harvest of American eels Anguilla rostrata, yet little is known about the underlying demographics and production rates that sustain these harvests. Chesapeake Bay subestuaries (Sassafras, Chester, Choptank, Patuxent, Potomac, and James rivers) are expected to provide productive but varying growth habitats for yellow‐stage American eels due to differences in land use, prey availability, and salinity. We compared length, age, growth, mortality, condition, and health (prevalence and incidence of parasitism by the swim bladder nematode Anguillicola crassus) of yellow American eels (n = 850) in the six principal subestuaries. As has been observed for other systems, female American eels in the Chesapeake Bay were larger, older, and heavier and had higher growth rates than male, intersexual, or undifferentiated American eels. Prevalence of male and intersexual individuals in the upper bay region was higher than that in the lower bay and higher than that reported for estuaries in South Carolina, Quebec, and the Hudson River, New York. American eel demographic attributes (gender, length, weight, condition, age, growth, and parasitism) differed substantially among the subestuaries. Individual growth rates ranged from 26.7 to 149.3 mm/year; the Choptank River had the highest mean growth rate (72.7 mm/year), and the Chester River had the lowest (60.2 mm/year). Estimated instantaneous loss rates (0.52–1.01 per year) did not vary systematically among subestuaries. Prevalence of parasitized American eels ranged from 17.8% to 72.0% and was higher in the upper bay subestuaries than in the lower bay. Swim bladder damage and Anguillicola crassus presence were not associated with American eel age or growth rate. In summary, female prevalence, growth rates, and condition were lower and parasite prevalence and intensity were higher in the less‐saline upper bay than in the lower bay, suggesting fundamental differences in the productivity and spawning contributions between these two regions.

Are Thirty-Five Days Enough to Observe the Stress-Reducing Effect of a Semiochemical Analogue on Chickens (Gallus gallus domesticus) Housed Under High Density?

Two similar 400-m2 buildings, each housing 8,400 broilers of a commonly used industrial strain, were used to test the effectiveness of the semiochemical treatment known as mother hen uropygial secretion analogue (MHUSA). The birds in 1 building were exposed to MHUSA continuously during a 35-d growing period, whereas those in the other building received a placebo. The experiment was then repeated using precisely the same conditions but with the building treatment reversed to control for any building effect. The purpose of the trial was to evaluate the effect of MHUSA on growing performances (live weights) and stress indicators observed from blood samples: heterophil-lymphocyte ratio and corticosterone level. Data analysis (ANOVA) showed that MHUSA-treated broilers had a higher mean growth rate, as shown by increased live weights at both d 17 and 35 (P < or = 0.001 and P < or = 0.001, respectively). After the 35-d growing period, we observed both lower heterophil-lymphocyte ratio (P < or = 0.001) and lower corticosterone level (P < or = 0.05) for birds treated with MHUSA compared with placebo, further indicating that the birds were less stressed. We conclude that constant diffusion of MHUSA in buildings used to house broilers might enhance the welfare and growth of the bird by reducing stress.

In this issue

In this issue

The interrelation of growth and disease resistance of different populations of juvenile Atlantic halibut ( Hippoglossus hippoglossus L.)

Growth of juvenile Atlantic halibut from three areas of the North Atlantic (Canada, Iceland and Norway) was studied in an experiment using individual tagged fish reared at 15°C for 85 days. Fish from each population were subsequently split into two groups and acclimatised to either 12°C or 18°C. The fish were then injected intra-peritoneally with a Vibrio anguillarum bacteria suspension and mortality monitored for 4 weeks. Growth rates of the Canadian population ranked lowest, whereas the Norwegian population had the highest mean growth rates (SGR=1.70% day −1, 1.62% day −1 and 1.53% day −1 for the Norwegian, Icelandic and Canadian populations, respectively). The halibut from Norway had the best survival following bacterial challenge (80%, 50% and 55% survival for the Norwegian, Icelandic and Canadian populations, respectively). Mortality was higher at 18°C than at 12°C in the Icelandic (62% at 12°C and 27% at 18°C) and Canadian (56% at 12°C and 32% at 18°C) fish, whereas a smaller difference between temperatures was observed in the Norwegian fish (25% at 12°C and 13% at 18°C). Fish that survived the challenge test were those that had grown fastest in the growth trial. Low, but significant, correlations between survival and size and growth were seen, but these correlations varied between populations. In the Canadian population, no correlation between size and growth and survival were seen; only size was correlated ( r=0.27) with survival in the Icelandic population, whereas both size ( r=0.18) and growth ( r=0.17) were correlated with survival in the Norwegian population.

Feeding of captive, tropical carcharhinid sharks from the Embley River estuary, northern Australia

Twenty carcharhinid sharks of 3 species were fed pilchards at different frequencies to examine feeding-growth relationships. These results are among the first in Australia on food intake and growth of wild-caught juvenile and sub-adult carcharhinids held in captivity. Mean consumption rates (± SE) for all feeding rations were 2.91% (± 0.28) body weight per day (BWD) for Carcharhinus dussumieri, 3.44% (± 0.40) BWD for C tilstoni and 3.35% (±0.34) BWD for Negaprion acutidens. N. acutidens had the highest consumption rate of 5.02% BWD at feeds d -1 . Highest mean growth rates were 0.78% (±0.11) BWD for C. dussumieri, 1.34% BWD (± 0.54) for C. tilstom and 1.12% (n = 1) BWD for N. acutidens. Maintenance ration estimates were 1.29% BWD for C. dussumieri, 1.31% BWD for N. acutidens. and 2.06% BWD for C. tilstoni. These are similar to literature estimates. High consumption rates did not always translate directly to high growth rates.

In situ gradostat for the study of a natural phytoplankton community with an experimental nutrient gradient

A new in situ gradostat was devised to study the dynamics of natural communities having nutrient gradients within aquatic habitats. This semi-enclosed mesocosm consisted of three components: i.e. three transparent, concentric cylindrical culture chambers, with diameters of 70, 60 and 40 cm, and 20 cm deep, supported by four flotation buoys, a medium reservoir, and a pump to supply the medium to the mesocosm. Water exchange between compartments was achieved via holes in the cylindrical walls, the number and size of the holes being chosen to regulate the rate of exchange. Sterile culture medium was pumped into the central (first) chamber and diffused outwards into the second and third chambers through the perforated walls. Suitable perforations could achieve a concentration gradient of up to 9.5 times between the first and third chambers within 12 h. The system was designed with the following characteristics: (1) an experimental semi-enclosed system in the natural environment; (2) to maintain equivalence with the external water except for the experimental factors; and (3) to form a manipulable gradient of experimental factors across the mesocosm. Using the in situ gradostat, the response of a natural phytoplankton community to a nitrate gradient was determined. A gradient from oligotrophic to eutrophic was maintained for 10 days in an oligotrophic pond. The mean growth rate of phytoplankton was lower in the eutrophic zone than that in the mesotrophic zone, where the highest mean growth rate was observed. The growth rate of each dominant phytoplankter showed its own pattern, but all rates were highest in the mesotrophic environment of the second chamber.

Seasonal changes in systemic hormone profiles and their relationship to patterns of fibre growth and moulting in goats of contrasting genotypes

In a 2 x 2 factorial experiment, seasonal changes in hormone and insulin-like growth factor-1 (IGF-1) profiles were compared in goats of two genotypes (Siberian (S) and Icelandic x Scottish feral (IF); n = 20 per genotype) with differing patterns of secondary fibre growth. Half of the goats of each genotype were fed rations containing either 100 or 180 g crude protein (CP)/kg dry matter. The period of secondary fibre growth was longer and the rate of growth greater in S than IF goats, but there were no effects of dietary protein concentration. Mean plasma concentrations of insulin, cortisol, T3 and T4 were higher in winter and those of prolactin, GH and IGF-1 concentrations were higher in summer. Growth of secondary fibre in S goats between January and March was associated with higher plasma prolactin and lower plasma insulin concentrations at this time than in IF goats in which there was no secondary fibre growth. The observed genotypic differences in times of onset and cessation of fibre growth were not associated with differences in the times of seasonal changes in any of the other hormones measured, and there was no effect of dietary protein level on hormone profiles. The higher mean growth rate and greater diameter of secondary fibre in S goats was associated with higher mean concentrations of T4 than in IF goats, throughout the study. Four S goats which exhibited secondary fibre growth during the summer had higher (P &lt; 0.05) mean plasma insulin concentrations than other animals of that genotype. It is suggested that genotypic differences in prolactin concentrations in late winter/spring may affect the time of onset of secondary fibre growth and that the cessation of growth may be influenced by differences in the timing of the seasonal decline of circulating prolactin concentrations to basal levels. However, the maintenance of relatively high plasma insulin concentrations may prolong growth in some circumstances. The higher concentrations of T4 in S than IF goats may have a role in the enhancement of the rate of fibre growth in these animals. The onset of moult in both genotypes was associated with the spring increase in plasma prolactin concentrations.

Growth rate related to genotype of 0-group cod at three environmental temperatures

Abstract Growth rates of cod of an initial weight of about one gram were studied at three environmental temperatures (6, 10, and 14° C) for about 70 days. Samples of all three groups of fish were genotyped for haemoglobin and several tissue enzymes by agar or starch gel electrophoresis. Size at termination of the experiment, regarded to represent individual growth rate, was studied separately for frequent genotypes within temperature groups. No clear associations between mean growth rate and genotypes of the enzymes LDH or PGI were found at any temperature. However, fish of the genotype Hb-I(2/2) showed the highest mean growth rate regardless of environmental temperature, and fish of genotype Hb-1(1/1) grew on average slowest at the two higher temperatures. This observation was partly in contrast to earlier findings indicating that the performance of the different genotypes is temperature dependent, with Hb-1(2/2) as the more efficient at lowest temperatures.

Effects of Elevated Winter Temperature on Seawater Adaptability, Sexual Rematuration, and Downstream Migratory Behaviour in Mature Male Atlantic Salmon Parr (Salmo salar)

In experiments with two different salmon (Salmo salar) stocks, elevated winter temperatures (Celsius) 4–9° above the ambient increased the degree of testicular resorption in previously mature male Atlantic salmon parr. Two-summer-old mature male parr maintained at a temperature 9° over the ambient for 5 mo (January–May) showed an increase in hypoosmoregulatory ability when challenged in seawater at the time of smoltification whereas parr kept at elevated temperature for various 2-mo periods (January–February, February–March, or March–April) failed to show this improvement. Furthermore, previously mature males kept at an elevated winter water temperature for either 2 or 5 mo showed a lower incidence of sexual rematuration, and consequently a higher mean growth rate, after one summer in sea pens. A river release experiment showed that rearing previously mature males at 4–7° above the ambient water temperature from December to April increased the number of downstream migrating fish to a level similar to that of immature smolts. We suggest the use of a simple method for enhancing the potential yield of ranched and cultured salmon from early maturing males by removing them from the stock population and rearing them over winter in heated water.

Effect of postweaning implantation of zeranol and dietary energy level on growth and reproductive performance of replacement beef heifers

Eighty-one heifer calves weaned at an average age of 6 mo were used to study the effect of postweaning zeranol implantation, on the growth and reproductive performance of heifers fed to grow slowly on three dietary energy levels. Forty heifers were implanted with 36 mg of zeranol at 30 d and again at 120 d postweaning. The remaining heifers were used as ummplanted controls. Within the implanted and control groups, heifers were subdivided into three groups and fed either a low, medium or high energy diet, which provided approximately 105, 130 and 160%, respectively, of NRC maintenance energy requirement, until 1 yr of age. The heifers were then turned out to pasture with hay supplementation. Heifers were exposed to bulls for 35 d at approximately 14 mo of age. Zeranol had no significant effect on growth. The effect of zeranol on the reproductive traits studied was not significant, although the trend was that the zeranol implanted heifers had lower calf crop born (52.3 vs. 63.6%) and lower incidence of calving difficulty (18.5 vs. 32.1%) than control heifers. The level of energy in the diet had a significant (P &lt; 0.01) effect on growth of the heifers, with those on the high energy diet having the highest mean growth rate, but no significant effect on reproductive performance. Key words: Zeranol, dietary energy, growth, reproduction, heifers

Response of irrigated lucerne to defoliation and nitrogen fertiliser

Abstract A 3-year-old stand of lucerne (Medicago media Per.) cv. ‘Wairau’ was spray irrigated and subjected to three defohatlon frequencies from spring to. autumn, after which all plots received a common management. Nitrogen fertiliser was applied to half the plots after each defoliation. Total dry-matter Yields calculated for a 12-month period were 24.0 and 28.2 tonnes DM/ha, and herbage N yields for control plots and those receivino N were 730 and 860 kg/ha respectively when the lucerne was defoliated at first flower. The highest mean growth rates (150 kg DM ha/day) occurred in midsummer, coinciding with maximum temperatures and radiation. Maximum response to N fertiliser also occurred at this time. Nitrogen fertiliser depressed spring lucerne yields. Defoliation management did not affect short-term N yields, but frequent defoliation reduced dry-matter yields and allowed extensive weed invasion. Nitrogen fertiliser did not affect weed yields.