553 research outputs found
Short communication: Effects of different protein sources on growth performance and food consumption of goldfish, Carassius auratus
Protein is one of the most important components in a fish diet. In aquaculture, the primary dietary animal protein source is fish meal, but its availability is limited and supply varies because of reductions in fish stocks related to factors such as climatic phenomena, and overexploitation and decline of ocean fisheries stocks. This variability can seriously affect aquaculture sustainability and provability, and therefore research in identifying alternative dietary protein sources has increased. Fish nutritionists have tried to use less expensive plant protein sources to partially or totally replace fish meal. ... The purpose of this study was to investigate food consumption and growth performance of goldfish fed diets containing only plant, only animal and plant-animal (50%-50%) derived protein source
The effects of boron management on soil microbial population and enzyme activities
Boron is an essential micronutrient required for plant growth. Soil microorganisms directly influence boron content of soil as maximum boron release corresponds with the highest microbial activity. The objective of this study is to determine the effects of different levels of boron fertilizer on microbial population, microbial respiration and soil enzyme activities in different soil depths in cultivated wheat soils. A randomized block design with three replications was used in this experiment. Field experiments were conducted to evaluate the effects of B levels (0, 1, 3, 6 and 9 kg ha–1 B) on soil microbial population in cultivated wheat (Triticum vulgare cultivar Dogu-88) soils. Statistical results showed a significant (p < 0.01) differences between B applications and microbial population and between B applications and microbial respiration in 0 to 30 and 30 to 60 cm soil depths. The highest population of bacteria, fungi, actinomycetes and CO2-C production were observed at 3 kg ha-1 B level in different growing periods of the plant and in different soil depths. Urease, phosphatase and dehydrogenase enzyme activities showed a significant (p < 0.01) positive correlation with B applications. The highest urease activity was observed in 6 kg ha-1 B level and the highest phosphatase and dehydrogenase enzyme activities were observed in 3 kg ha-1 B level in harvest period in both soil depths.Key words: Boron management, soil microbial population, urease activity, phosphatase activity, dehydrogenase activity
Effects of strip and full-width tillage on soil carbon IV oxide-carbon (CO2-C) fluxes and on bacterial and fungal populations in sunflower
In strip tillage system, planting lines are cultivated while the inter-row spaces are left undisturbed. The objective of this study is to determine the effects of strip tillage and full-width tillage treatments on soil carbon IV oxide-carbon (CO2-C) fluxes, bacterial and fungal populations in growing period of sunflower (Helianthus annus). A row-crop rotary hoe with C type blades was used to create three strip widths by changing the connection of blades of the rotary hoe on the flanges. Strip widths were 22.5 (T30), 30.0 (T40) and 37.5 cm (T50). The full-width tillage practice (moldboard plow + disc harrow + leveler) gave 100% surface soil disturbance (T100) and was included in the experiment to make comparisons with the strip tillage system. A randomized complete block design with three replications was used. During the growth of the sunflower, periodic measurements of CO2-C fluxes and bacterial and fungal populations were made. Significant (p < 0.01) differences in CO2-C fluxes, microbial populations, soil bulk density and total porosity were observed between the different tillage systems. Highest CO2-C fluxes, bacteria populations and total porosity were observed in the full-width T100 application and the lowest values were observed in the T30 treatment during flowering and harvesting periods. Increasing tillage intensity increased soil CO2-C fluxes and bacteria population, but decreased fungi population and soil bulk density.Key words: Carbon IV oxide-carbon flux, soil bacteria and fungi, strip tillage, full-width tillage, sunflower
The effects of oxygen supplementation on growth and survival of rainbow trout (Oncorhynchus mykiss) in different stocking densities
In this study, the effects of oxygen supplementation in different stocking densities of rainbow trout (Oncorhynchus mykiss) on the specific growth rates (SGR), feed conversion ratios (FCR) and survival rates were investigated in a commercial-scale culture system. High density cultures were maintained in a total of nine (12 m^3) flow-through systems supplemented with O2. Initial stocking rates for 3 different treatments with three replicates were 26.88±0.30 (low density), 36.72±0.26 (medium density) and 55.03±0.14kg m^-3 (high density), corresponding to a total of 5800, 8000 and 12000 fish/tank, respectively. Water flow rate for each tank was maintained at 11±1.1 L sec^-1 (660 L min^-1) over the study period for each raceway, and the temperature was 12.3±0.8°C throughout the experimental period. At the end of the study, there were no significant differences in the survival rates and SGR among treatments (p>0.05). However, FCR was negatively affected in the high density treatment (p<0.05). Overall, our results indicated that oxygen supplementation supported fish growth and survival in high stocking densities. However, high production cost is prohibitive and further studies are required to reduce costs
Antimicrobial studies on three Hypericum species from Turkey
The antimicrobial activity of several extracts and fractions of some Hypericum species (H. rupestre Jaub. & Spach, H. vacciniifolium Hayek & Siehe and H. imbricatum Poulter) was investigated using the disc diffusion method against Escherichia coli ATCC 11230, Staphylococcus aureus ATCC 6538P, Klebsiella pneumoniae UC57, Micrococcus luteus La 2971, Bordetella bronchiseptica ATCC 19395, Proteus vulgaris ATCC 8427, Pseudomonas aeruginosa ATCC 27853, Corynebacterium xerosis CCM 7064, Mycobacterium smegmatis CCM 2067, Bacillus subtilis ATCC 6633, Aeromonas hydrophila ATCC 49803, Candida albicans ATCC 10231, Saccharomyces cerevisiae ATCC 9730, Kluyveromyces fragilis NRRL 2415 and Rhodotorula rubra CCY. The methanol extract and chloroform fraction of H. vacciniifolium, as well as the methanol extracts, butanol and chloroform fractions of both H. rupestre and H. imbricatum, showed good antimicrobial activity against especially Gram-positive bacteria and the Gram-negative bacterium Bordetella bronchiseptica. The methanol extracts and fractions did not have antifungal activity. The results of the study support the use of these specimens in Turkish traditional medicine to treat skin and eye infections
Morphological malformations of the sea bass (Dicentrarchus labrax): Comparison between hormone injected and non-injected fish
In this study, fertilization, hatching and deformation rate of the eggs, and larvae obtained from hormone injected (HI) and non-injected broodstock (NHI), were determined. In the experiment, no differences were observed in the groups’ fertilization rates (p>0.05). Hatching rate was found higher in the HI group (p<0.05). During the experiment, malformations such as spinal fluid accumulation, saddleback, air-bladder deformation and general body deformations were observed in both groups. For the NHI group, saddleback rate was found 5.13±0.55%, air-bladder deformation rate was found 1.43±0.13%, spinal fluid accumulation was found 2.33±1.33% and general body deformation rate was found 3.76±0.23% (p<0.05). As a result, it was determined that the deformation rate increased with hormone injection (p<0.05)
Joint Astrophysics Nascent Universe Satellite:. utilizing GRBs as high redshift probes
The Joint Astrophysics Nascent Universe Satellite (JANUS) is a multiwavelength cosmology mission designed to address fundamental questions about the cosmic dawn. It has three primary science objectives: (1) measure the massive star formation rate over 5 ≤ z ≤ 12 by discovering and observing high-z gamma-ray bursts (GRBs) and their afterglows, (2) enable detailed studies of the history of reionization and metal enrichment in the early Universe, and (3) map the growth of the first supermassive black holes by discovering and observing the brightest quasars at z ≥ 6. A rapidly slewing spacecraft and three science instruments – the X-ray Coded Aperture Telescope (XCAT), the Near InfraRed Telescope (NIRT), and the GAmma-ray Transient Experiment for Students (GATES) – make-up the JANUS observatory and are responsible for realizing the three primary science objectives. The XCAT (0.5–20 keV) is a wide field of view instrument responsible for detecting and localizing ∼60 z ≥ 5 GRBs, including ∼8 z ≥ 8 GRBs, during a 2-year mission. The NIRT (0.7–1.7 µm) refines the GRB positions and provides rapid (≤ 30 min) redshift information to the astronomical community. Concurrently, the NIRT performs a 20, 000 deg2 survey of the extragalactic sky discovering and localizing ∼300 z ≥ 6 quasars, including ∼50 at z ≥ 7, over a two-year period. The GATES provides high-energy (15 keV −1.0 MeV) spectroscopy as well as 60–500 keV polarimetry of bright GRBs. Here we outline the JANUS instrumentation and the mission science motivations
Power density of a bare electrodynamic tether generator
The maximum performance of bare electrodynamic tethers as power generating systems under OML-theory is analyzed. Results show that best performance in terms of power density is achieved by designing the tether in such a way to increase ohmic impedance with respect to plasma contact impedance, hence favoring longer and thinner tethers. In such condition the corresponding optimal value of the load impedance is seen to approach the ohmic impedance of the conducting tether. At the other extreme, when plasma contact impedance dominates (which is not optimal but can be relevant for some applications) optimum power generation is found by matching the load impedance with an effective tether-plasma contact impedance whose expression is derived
Pituitary Insufficiency and Hyperprolactinemia Associated with Giant Intra- and Suprasellar Carotid Artery Aneurysm
Pituitary insufficiency secondary to internal carotid artery (ICA) aneurysm is a very rare condition. Its prevalence is reported as 0.17% (Heshmati et al., 2001). We present a case of pituitary insufficiency and hyperprolactinemia secondary to suprasellar giant intracranial aneurysm. A 71-year-old man was admitted to our clinic with symptoms of hypopituitarism, hyperprolactinemia, and visual field defect. His pituitary MRI and cerebral angiography revealed a giant saccular aneurysm filling suprasellar cistern arising from the ophthalmic segment of the right ICA. Endovascular treatment was performed on the patient to decrease the mass effect of aneurysm and improve the hypophysis dysfunction. After treatment, his one-year follow-up showed the persistence of hypophysis insufficiency, decrease of prolactin (PRL) level, and normal visual field. An intracranial aneurysm can mimic the appearance and behavior of a pituitary adenoma. Intracranial aneurysms should be taken into consideration in the situation of hypopituitarism and hyperprolactinemia. It is important to distinguish them because their treatment approach is different from the others
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