scholarly journals PRODUCTIVIDAD PRIMARIA EN LA CIENAGA GRANDE DE SANTA MARTA, COLOMBIA

2016 ◽  
Vol 19 ◽  
Author(s):  
Carlos A. Hernández J. ◽  
Klaus Gocke
Keyword(s):  
Primary Productivity ◽  
Coastal Lagoon ◽  
Mean Value ◽  
High Concentration ◽  
Water Turbidity ◽  
High Particle Concentration ◽  
High Particle ◽  
Wide Range ◽  
The Mean ◽  
The Caribbean

Between January 1987 and January 1988 the primary productivity and related parameters were studied in the Ciénaga Grande de Santa Marta. The Ciénaga is a coastal lagoon with an area of 423 km'2 and mean depth of 1.6 m, which is located at the Caribbean coast of Colombia. The salinity fluctuates seasonally within a wide range. The system is characterized by a high concentration of seston and a great primary productivity. The concentration of chlorophyll " a " ranged from 5.6to 181 ug Ii , the mean value was 59 ug I i . The concentration of proteins was within the extremes of 0.9 and 9.5 mg I"i f the mean value was 4.2 mg I ] . The gross primary productivity in the central part of the Ciénaga amounted to 1690 g C m*2 per year. Considering the temporal fluctuation in the whole system the lowest and highest values were 1.40 and 16.3 g C rrr2 per day. Highest productivity values were encountered when the salinity was low. The primary productivity is controlled by water turbidity and availability of nutrients, thus, seasonal continental waters. The photosynthetic laver ¡s restricted to less than 1.5 m due to the high particle concentration. The mean N: P relation was 4:1 which indicates that the nitrogen compounds are the limiting nutrientes. The high primary productivity sustains an important local fishery. The coastal area in the vicinity of the Ciénaga Grande is benefitted by the export of particulated and dissolved organic matter produced in excess within the coastal lagoon.

A Comparison of Physiological Demand between Self-Propelled and Motorized Treadmill Exercise

2018 ◽  
Vol 7 (4) ◽  
pp. 13-21
Author(s):  
Todd Backes ◽  
Charlene Takacs
Keyword(s):  
Respiratory Exchange Ratio ◽  
Treadmill Exercise ◽  
Cardiopulmonary Exercise Testing ◽  
Mean Value ◽  
The Self ◽  
Mixing Chamber ◽  
Wide Range ◽  
The Subject ◽  
The Mean ◽  
Computer Controlled

There are a wide range of options for individuals to choose from in order to engage in aerobic exercise; from outdoor running to computer controlled and self-propelled treadmills. Recently, self-propelled treadmills have increased in popularity and provide an alternative to a motorized treadmill. Twenty subjects (10 men, 10 women) ranging in age from 19-23 with a mean of 20.4 ± 0.8 SD were participants in this study. The subjects visited the laboratory on three occasions. The purpose of the first visit was to familiarize the subject with the self-propelled treadmill (Woodway Curve 3.0). The second visit, subjects were instructed to run on the self-propelled treadmill for 3km at a self-determined pace. Speed data were collected directly from the self-propelled treadmill. The third visit used speed data collected during the self-propelled treadmill run to create an identically paced 3km run for the subjects to perform on a motorized treadmill (COSMED T150). During both the second and third visit, oxygen consumption (VO2) and respiratory exchange ratio (R) data were collected with COSMED’s Quark cardiopulmonary exercise testing (CPET) metabolic mixing chamber system. The VO2 mean value for the self-propelled treadmill (44.90 ± 1.65 SE ml/kg/min) was significantly greater than the motorized treadmill (34.38 ± 1.39 SE ml/kg/min). The mean R value for the self-propelled treadmill (0.91 ± 0.01 SE) was significantly greater than the motorized treadmill (0.86 ± 0.01 SE). Our study demonstrated that a 3km run on a self-propelled treadmill does elicit a greater physiological response than a 3km run at on a standard motorized treadmill. Self-propelled treadmills provide a mode of exercise that offers increased training loads and should be considered as an alternative to motorized treadmills.

The Mode of Excretion of Ammonia and Urea in Xenopus Laevis

1961 ◽  
Vol 38 (4) ◽  
pp. 695-705
Author(s):  
J. B. BALINSKY ◽  
E. BALDWIN
Keyword(s):  
Xenopus Laevis ◽  
Blood Concentration ◽  
Concentration Ratio ◽  
Ammonia Excretion ◽  
Ammonia Concentration ◽  
Mean Value ◽  
Urea Excretion ◽  
Wide Range ◽  
Glomerular Filtrate ◽  
The Mean

1. Eighty-two single determinations of ammonia and urea excretion by Xenopus laevis indicated that the percentage of ammonia varied from 40 to 80%, with a mean value of 62%. 2. Measurements of excretion on successive days after feeding showed that a large amount of ammonia was produced soon after feeding, but that ammonia excretion declined rapidly. Urea excretion, not so high initially, remained more or less constant until the third or fourth day, often exceeding ammonia excretion at that time. Thereafter, it also declined and the excretion of both substances reached a constant starvation level by the fifteenth day. 3. Both ammonia and urea excretion were equally affected by temperature. The Q10's were near 2 in the range 20-30° C., but greater in the range 10-20° C. 4. At least 86% of ammonia, and 81% of urea were excreted through the cloaca. 5. The mean 24 hr. urine output of Xenopus at 20% C. was 23.6 ml. per 100 g. body weight. 6. Although the blood ammonia concentration did not appear to be zero, the urine/blood concentration ratio of ammonia was greater than 100. The urine/blood concentration ratio of urea was not significantly different from unity, and constant over a very wide range of concentrations. 7. The above result is interpreted to indicate passive glomerular filtration of urea, and little or no tubular reabsorption of water. 8. It is suggested that ammonia is formed in the kidney, and actively secreted into the glomerular filtrate.

scholarly journals Clusters of intramembrane particles associated with binding sites for alpha-bungarotoxin in cultured chick myotubes.

1979 ◽  
Vol 82 (2) ◽  
pp. 494-516 ◽  
Author(s):  
S A Cohen ◽  
D W Pumplin
Keyword(s):  
Acetylcholine Receptors ◽  
High Concentration ◽  
High Particle Concentration ◽  
High Particle ◽  
Cholinergic Synapses ◽  
Muscle Cultures ◽  
High Concentrations ◽  
Nerve Muscle ◽  
Alpha Bungarotoxin ◽  
Angular Particles

Developing chick myotubes in tissue culture were freeze-fractured to yield complementary replicas of large areas of membrane. Regions of muscle fibers with high concentrations of acetylcholine receptors were identified by binding of fluorescent-labeled alpha-bungarotoxin. Membranes in such regions contained clusters of large (100 A Diam) angular particles, similar in appearance to particles found in postsynaptic membranes of cholinergic synapses. Particles appeared in apposing areas of cytoplasmic and external leaflets but were more prevalent in the cytoplasmic leaflet. The areas of high particle concentration were coextensive with the fluorescence due to bound toxin. Treatment of cultures with tetrodotoxin increased the size of fluorescent spots and areas of high concentration of particles relative to those found in control cultures. In muscle cultures grown in the presence of spinal cord explants, some neurites contacted and innervated nearby myotubes. Intense fluorescence due to binding or alpha-bungarotoxin was present at portions of such neurite-myotube contacts. At these same portions, a high concentration of large angular particles was present in the sarcolemma adjacent to the neurite. In addition, an ordered arrangement of large particles was seen in the cytoplasmic leaflet of the neuronal plasmalemma directly apposing the muscle. The possible significance of these arrangements is discussed. Clusters on myotubes tended to be larger (contain more particles) when they occurred in groups, defined as three or more clusters with an intercluster distance of less than 0.5 micrometers. Clusters were also larger in myotubes treated with tetrodotoxin and in myotubes adjacent to some neurites in nerve-muscle cocultures. Several depressions containing particles similar to those in the clusters were found in the sarcolemma. The implications of these depressions are discussed in light of current theories of incorporation of proteins into cell membranes.

Effects of left atrial pressure on the pulmonary vascular response to hypoxic ventilation

1991 ◽  
Vol 70 (5) ◽  
pp. 1991-1995 ◽  
Author(s):  
S. A. Gu ◽  
J. Ducas ◽  
U. Schick ◽  
R. M. Prewitt
Keyword(s):  
Arterial Pressure ◽  
Left Atrial ◽  
Pulmonary Arterial Pressure ◽  
Mean Value ◽  
Atrial Pressure ◽  
Left Atrial Pressure ◽  
Vascular Response ◽  
Wide Range ◽  
Pulmonary Arterial ◽  
The Mean

We investigated the effects of hypoxic ventilation on the pulmonary arterial pressure- (P) flow (Q) relationship in an intact canine preparation. Mean pulmonary P-Q coordinates were obtained during hypoxic ventilation and during ventilation with 100% O2 at normal and at increased left atrial pressure. Specifically, we tested the hypothesis that, over a wide range, changes in left atrial pressure would alter the effects of hypoxic ventilation on pulmonary P-Q characteristics. Seven dogs were studied. When left atrial pressure was normal (5 mmHg), the mean value of the extrapolated intercept (PI) of the linear P-Q relationship was 10.9 mmHg and the slope (incremental vascular resistance, IR) of the P-Q relationship was 2.2 mmHg.l-1.min. Hypoxic ventilation increased PI to 18 mmHg (P less than 0.01) but did not affect IR. Subsequently, during ventilation with 100% O2, when left atrial pressure was increased to 14 mmHg by inflation of left atrial balloon, PI increased to 18 mmHg. IR was 1.6 mmHg.l-1.min. Again, hypoxic ventilation caused an isolated change in PI. Hypoxia increased PI from 18 to 28 mmHg (P less than 0.01). As in the condition of normal left atrial pressure, hypoxic ventilation did not affect IR. We conclude that, in an anesthetized intact canine preparation, hypoxic ventilation causes an isolated increase in the extrapolated pressure intercept of the pulmonary P-Q relationship. Furthermore the effects of hypoxic ventilation on pulmonary P-Q characteristics are not affected by the resting left atrial pressure.

scholarly journals Assessment of the Current Pollution Status of Jabi Lake in the Federal Capital Territory, Abuja, Nigeria

2019 ◽  
Vol 51 (3) ◽  
pp. 324
Author(s):  
Cyril Kanayochukwu Ezeamaka ◽  
Sadiq Queen ◽  
Daful Mwanret ◽  
Ogbole Moses ◽  
Anjide Theresa Wado
Keyword(s):  
Oxygen Demand ◽  
Mean Value ◽  
Who Guidelines ◽  
High Concentration ◽  
Domestic Water ◽  
Secchi Disc ◽  
Flame Atomic Absorption ◽  
Pollution Status ◽  
The Mean ◽  
Proactive Measures

This paper was aimed at providing the pollution status of Jabi Lake, FCT Abuja. 13 parameters were tested from raw water collected four sampling points. The physicochemical parameters were measured using Hanna multiparametric meter, while transparency was measured using Secchi disc. Dissolved oxygen, Biological and Chemical oxygen demand were measured titrimetrically using standard method. The concentrations of the metals were determined in triplicates. Flame atomic absorption spectrometer was used in the analysis as well as descriptive statistics (mean, standard deviation) and standard error. The Nigerian Industrial Standard and WHO guidelines for domestic water were used to compare the results of the water from the lake. The study reveals that the mean turbidity ranged between 21.6 – 24.2cm and is above the recommended limits of both WHO and NIS. The range of pH was between 6.3 and 8.8. pH is within a neutral range. The study reveals that the mean value of TDS and electrical conductivity is below the recommended limit of both WHO and NIS guidelines. The study shows that there is high concentration of some heavy metals (Cd, Cu, Ni, Mn, Zn, and Fe) in Jabi Lake. Cd, Zn, Fe and Ni are above the permissible limits of the NIS and WHO guidelines, which is an indication of pollution. The study, therefore, recommends that proactive measures be taken on environmental laws in FCT and that environmental/health worker and non-governmental bodies be active in enlightenment campaigns that will alert members of the public to the harm being caused to this important ecosystem.

scholarly journals Progress towards clover cyst nematode resistant white clover

1996 ◽  
pp. 237-241
Author(s):  
J. Van den Bosch ◽  
C.F. Mercer
Keyword(s):  
White Clover ◽  
Trifolium Repens ◽  
Egg Production ◽  
First Generation ◽  
Control Method ◽  
Dry Weight ◽  
Mean Value ◽  
Cyst Nematode ◽  
Wide Range ◽  
The Mean

Clover cyst nematode (Heterodera trifolii) reduces growth and nutrient uptake of white clover (Trifolium repens) in New Zealand, and breeding resistant cultivars is the preferred control method for ecological and economic reasons. Resistant and susceptible selections were taken from a wide range of white clover seedlines. Selected plants were intercrossed and reselected over two cycles of selection. Cysts per gram of root dry weight (cysts/ g) was the measure of resistance used, with low cysts/g plants being more resistant. The mean cysts/ g value of the progenies from resistant parents was 69% of the mean value of the progenies from susceptible parents in the first generation, and 38% in the second generation. Root weights were similar, while the resistant selections had 58% and 34% (first and second generations respectively) of the number of cysts in the susceptible selections. There were no immune plants (0 cysts) in the first generation and only two in the second. Counts were made of cysts, eggs per cyst and eggs per plant on clones of two resistant and two susceptible genotypes. The resistant genotypes had lower counts than the susceptible genotypes in terms of cysts per plant (means of 6 cf. 108), eggs per cyst (11 cf. 21) and eggs per plant (35 cf. 1650). The differences in numbers of cysts between resistant and susceptible lines increased during two generations of selection, supporting earlier results that indicated that progress in breeding for resistance was possible. Furthermore, the resistance is also acting on clover cyst nematode egg production which would further reduce recruitment to later generations of clover cyst nematode. Keywords: breeding, Heterodera trifolii, resistance, screening, selection, Trifolium repens

scholarly journals Hereditary high concentration of glutathione in canine erythrocytes associated with high accumulation of glutamate, glutamine, and aspartate

Blood ◽  
1982 ◽  
Vol 59 (5) ◽  
pp. 883-889 ◽  
Author(s):  
Y Maede ◽  
N Kasai ◽  
N Taniguchi
Keyword(s):  
Amino Acids ◽  
Feedback Inhibition ◽  
Clinical Signs ◽  
Mean Value ◽  
Glutathione Metabolism ◽  
High Concentration ◽  
Normal Range ◽  
High Accumulation ◽  
The Mean ◽  
Cysteine Synthetase

We have found a dog family in which there were five cases of increased red cell glutathione corresponding to four to five times the normal concentration without any clinical signs. In the present study, we mainly examined the concentrations of free amino acids in the erythrocytes, plasma, and urine of two of the dogs, and we demonstrated that the concentrations of glutamate, aspartate, and glutamine in their erythrocytes increases to 92, 63, and 13 times the mean value in the normal blood, respectively. There were no changes observed in the other amino acids as compared to normal, although the glycine and histidine in the erythrocyte showed slight increases. The concentrations of amino acids in the plasma and urine of the dogs were almost equal to normal ones. The activities of some of the enzymes involved in the glutathione metabolism in the erythrocytes from the two dogs were all within the normal range. The increased level of glutathione could be explained by the fact that the feedback inhibition of gamma-glutamyl cysteine synthetase by glutathione was released by the high levels of glutamate in the erythrocytes.

scholarly journals Potassium isotopic variability and implications for <sup>40</sup>K-based geochronology

2020 ◽  
Author(s):  
Leah E. Morgan
Keyword(s):  
Neutron Fluence ◽  
Radioactive Decay ◽  
Mean Value ◽  
Decay Constants ◽  
Wide Range ◽  
The Mean ◽  
Precision And Accuracy ◽  
Ar Geochronology ◽  
Isotopic Measurements ◽  
Silicate Materials

Abstract. 40Ar/39Ar and K-Ar geochronology assume that 40K/K values are invariant among the sample of interest, the co-irradiated neutron fluence monitor (standard), and the material used to measure decay constants. Until recently, this assumption was reasonable due to the small K isotope (41K, 40K, 39K) variability found in many terrestrial samples and the negligible effect of any variation relative to the precision of the determined age. The recent discovery of measurable δ41K variability in terrestrial samples now questions this assumption. Although δ41K values for some neutron fluence monitors have now been reported, potassium isotopes are not routinely measured on samples dated by the 40Ar/39Ar method even though a wide range of silicate materials were found to vary by > 2.5 ‰. Further, the 40K decay constants used in 40Ar/39Ar geochronology are based on activity counting of radioactive decay in K-rich salts. These salts have not been measured for δ41K, yet evaporites have been shown to vary by > 1 ‰ from the mean value of silicates. The potential effects of δ41K variability on 40Ar/39Ar ages are illustrated using the case of the ca. 28.2 Ma Fish Canyon sanidine (FCs) and the ca. 99 Ma Mt. Dromedary Biotite (GA-1550). If the two standards have δ41K values as measured and the material used to determine decay constants is appropriately represented by δ41K of evaporites, the age of FCs is underestimated by ca. 7 ka (0.25 ‰). Although this is a small effect, such bias is becoming important as the analytical precision and accuracy of isotopic measurements and calculation of 40Ar/39Ar ages continue to improve.

scholarly journals Enzyme-Linked Immunosorbent Assay for Measurement of Cytomegalovirus Glycoprotein B Antibody in Serum

2010 ◽  
Vol 17 (5) ◽  
pp. 836-839 ◽  
Author(s):  
Daniel J. Hackett ◽  
Changpin Zhang ◽  
Carla Stefanescu ◽  
Robert F. Pass
Keyword(s):  
Immunosorbent Assay ◽  
Geometric Mean ◽  
Mean Value ◽  
Glycoprotein B ◽  
Enzyme Linked Immunosorbent Assay ◽  
Igg Antibody ◽  
Negative Results ◽  
Wide Range ◽  
The Mean ◽  
Antibody Levels

ABSTRACT Measurement of antibody to cytomegalovirus (CMV) glycoprotein B (gB) is valuable in the assessment of the antibody response to infection and to gB-containing vaccines. For this purpose, an enzyme-linked immunosorbent assay (ELISA) with a recombinant CMV gB molecule as the antigen was evaluated. Sera from 168 anti-CMV IgG-positive and 100 seronegative subjects were used to evaluate the anti-gB antibody assay. A cutoff optical density (OD) that would distinguish gB antibody-positive from -negative sera was established. Titers of antibody to gB determined by endpoint dilution were compared with those calculated using regression analysis. The run-to-run and interoperator reproducibilities of results were measured. The mean OD + 5 standard deviations from 50 anti-CMV IgG antibody-negative sera (0.2472) was used as the cutoff between anti-gB antibody-positive and -negative results. All sera from 100 anti-CMV IgG-seronegative subjects were negative for antibody to gB. All but 1 of 168 sera from seropositive subjects were positive for antibody to gB. Observed antibody levels based on titration to the endpoint were very similar to results calculated using linear regression. The run-to-run consistency of endpoints was excellent, with 38 runs from one operator and 48 runs from another all giving results within 1 dilution of the mean value for each of three anti-CMV IgG antibody-positive serum pools. The geometric mean titer of antibody to gB for 99 sera from seropositive blood donors was 1/10,937. This ELISA gives accurate and reproducible results for the relative quantity of anti-CMV gB IgG in serum over a wide range of antibody levels.

The appraisal of fineness in greasy wool sale lots

1975 ◽  
Vol 85 (1) ◽  
pp. 45-52 ◽  
Author(s):  
K. J. Whiteley ◽  
D. Charlton
Keyword(s):  
Confidence Interval ◽  
Fibre Diameter ◽  
Mean Value ◽  
Wide Range ◽  
The Mean ◽  
The Relationship

SUMMARYRelationships among quality number, crimp frequency and. fibre diameter of sale lots are reported for a wide range of Australian wools, the quality number appraisals being those of the selling broker and the successful bidder at auction.Results show that sale lots classified as having the same quality number exhibit a 95% confidence interval of ± 2·5 μm about the mean value. This variation is attributed first to the dependence of quality number on staple crimp frequency and secondly to the strength of the relationship between crimp frequency and fibre diameter.

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