Scientific Results of the BRYOTROP Expeditioni to Zaire and Rwanda 1. The ecology of epiphytic bryophytes on Mt. Kahuzi (Zaire)

1994 ◽  
Vol 9 (1) ◽  
pp. 137-152 ◽  
Author(s):  
Jan-Peter Frahm
Keyword(s):  
Life Form ◽  
Growth Conditions ◽  
Sudden Increase ◽  
Low Light ◽  
Ph Measurements ◽  
Tropical Mountains ◽  
Host Trees ◽  
The Mean ◽  
Scientific Results ◽  
Forest Line

Along a transect from 900 m to 3300m elevation, various ecological parameters concerning epiphytic bryophytes have been studiesd. The most characteristic life form between 900 and 2300 m elevation is the dendroid, which is interpreted as an adaptation to better gas exchange under the unfavourable conditions (low light, high air humidity) of the rain forest. Above 2500 m, cushions are the predominant lif form. The cushion are 2-5 cm high but can reach 50 cm at the forest line. In spectacular cases, moss balls are formed up to 1 m in diameter. PH measurements of the bark of host trees revealed values between 4.1 and 6.2, which is in accordance with result from South America and SE-Asia. The bryophyte cover on soil is very low (<5%) below 2700 m but raises to 90% in the subalpine ericaceous belt, but not in the subalpine Senecio-belt. The percentage cover of bryophytes on bark increases from 5 to 80% in the transect with increasing elevation, and the light intensity increases from <1% to 50%. The mean annual temerature decreases continously from 20.6°C at 900 m elevation to 2.5° at 4500 m elevation. This allows a comparison of the growth conditions of bryohyte species occurring disjunct in the oceanic parts of the temperate regions and the tropical mountains. The phytomass of epiphytic bryophytes per m² and per ha increases synchronously in the transect. There is a sudden increase from 8-44 kg/ha in 900-1300 m to 100-600 kg/ha in elevationis between 1900 and 2900 m. Maximum values of 6 tonnes/ha are found at the forest line , being 750 time higher than the lowest value in the lower part of the transect. The water storing capacity of epiphytic bryophytes is 20-60 1/h at elevations between 900 and 1300 m, 130-2000 1/ha between 1900 and 2900 m and 18000 1/ha at the forest line. The latter is 18% of the estimated rainfall.

Nutrient Concentrations in Soil Solution in an Alfisol under Grapefruit Production

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 498d-498
Author(s):  
Z.L. He ◽  
A.K. Alva ◽  
D.V. Calvert ◽  
D.J. Banks ◽  
Y.C. Li
Keyword(s):  
Soil Solution ◽  
Fine Sand ◽  
Drainage Water ◽  
Tree Canopy ◽  
Nutrient Concentrations ◽  
Sour Orange ◽  
Parallel Study ◽  
Ph Measurements ◽  
The Mean ◽  
N Rates

A field experiment was conducted in a Riviera fine sand (Alfisol) with 25-year-old `White Marsh' grapefruit trees on Sour orange rootstock to monitor the downward transport of nutrients from fertilization practices. Fertilizer was applied as either dry granular broadcast (three applications/year) or fertigation (15 applications/year) at N rates of 56, 112, 168, and 336 kg/ha per year using a N:P:K blend (1.0:0.17:1.0). Soil solution was sampled bi-weekly from suction lysimeters, installed under the tree canopy, about 120 cm from the tree trunk, at two depths representing above (120 cm) and below (180 cm) the hard pan. The concentrations of K, Ca, and Mg were greater at the 180- than at 120-cm depth, whereas, the converse was true with respect to the concentration of P in soil solution. Over a 2-year period, the mean concentrations of P and K varied from 0.031-0.976 and 150-250 mg·L–1, respectively. Increased rate of fertilization also appeared to increase the concentrations of Ca and Mg in the soil solution. This could be due to effects of slight acidification of the soil with increased rates of ammonium form of N. A parallel study on pH measurements has shown evidence of soil acidification, under the tree canopy, with increased rates of ammonium fertilization. In a bedded grove, the soil solution above the hard pan is likely to seep into the water furrow, which is discharged into the drainage water.

Effects of a sudden increase in natural mortality of adults on a population of the common snapping turtle (Chelydra serpentina)

1991 ◽  
Vol 69 (5) ◽  
pp. 1314-1320 ◽  
Author(s):  
Ronald J. Brooks ◽  
Gregory P. Brown ◽  
David A. Galbraith
Keyword(s):  
Clutch Size ◽  
Research Area ◽  
Effective Density ◽  
Egg Mass ◽  
Sudden Increase ◽  
Chelydra Serpentina ◽  
Density Dependent ◽  
Snapping Turtles ◽  
The Mean ◽  
Clutch Mass

A northern population of snapping turtles (Chelydra serpentina) centred around Lake Sasajewun in the Wildlife Research Area in Algonquin Park, Ontario, has been studied and individually marked since 1972. From 1972 to 1985, annual mortality and survivorship of adult females had been estimated at 1 and 96.6%, respectively, and only six dead turtles were found. Lake Sasajewun's population of C. serpentina was estimated in 1978–1979 and 1984–1985 at 38 and 47 adults, respectively. From 1976 to 1987, total number of nests found in the study area remained fairly constant and there were no significant changes in mean clutch size, mean clutch mass, or mean egg mass. On the main nest site, recruitment from 1976 to 1987 was 1.15 (1.8%) new females per year. From 1987 to 1989, we found 34 dead adult snapping turtles in the Wildlife Research Area. Observations of freshly dead animals indicated that most were killed by otters (Lutra canadensis) during the turtles' winter hibernation. A few uninjured turtles also died of septicemia in early spring shortly after emerging from hibernation. The estimated number of adults in Lake Sasajewun was 31 in 1988–1989, and the minimum number of adult residents known to be alive in the lake dropped from 47 in 1986 to 16 in 1989. In 1986 and 1987, annual adult female survivorship was estimated at 80 and 55%, respectively, and estimated numbers of nesting females declined from 82 in 1986 to 71 and 55 in 1987 and 1988, respectively. The actual number of nests found declined by 38 and 20% over the same periods. Although no significant differences occurred in mean egg mass or mean clutch size between 1987 and 1989 and earlier years, the mean clutch mass in 1988 was larger than in 1977 or 1978. This difference appeared to be due to a gradual increase in the mean age and body size of breeding females rather than to density-dependent changes. Recruitment into the adult breeding female population in 1987–1989 remained less than two individuals per year. Hatchling survival and number of juveniles were low throughout the study. Our observations support the view that populations of species with high, stochastic juvenile mortality and long adult life spans may be decimated quickly by increased mortality of adult animals, particularly if numbers of juveniles and immigrants are low. Recovery of such populations should be very slow because of a lack of effective density-dependent response in reproduction and recruitment.

scholarly journals Outcome Analysis of Osteosynthesis Versus Hemiarthroplasty for the Treatment of Displaced Femoral Neck Fracture in Young Elderly Patient

2021 ◽  
pp. 53-59
Author(s):  
Muhammad Rafique Joyo ◽  
Nizam Ahmed ◽  
Ghazanfar Ali Shah ◽  
Aftab Alam Khanzada ◽  
Tanveer Afzal ◽  
...  
Keyword(s):  
Femoral Neck ◽  
Femoral Neck Fracture ◽  
Functional Performance ◽  
Clinical Status ◽  
The Elderly ◽  
Recurrent Dislocation ◽  
Outcome Analysis ◽  
Sudden Increase ◽  
Neck Fracture ◽  
The Mean

This study was designed to compare the osteosynthesis and hemiarthroplasty treatment among the elderly population and evaluate the postoperative functional performance of these two recommended treatments of a displaced femoral neck fracture. Methodology: This retrospective study was conducted in Bone Care trauma center Heerabad  Hospital Hyderabad Pakistan from March 2019 to March 2020. A total of 74 patients of age between  60 to 70 years were selected. All the selected patients were diagnosed with femoral neck fractures (Garden’s III and IV). Harris's hip score was used to evaluate the clinical status of patients with pain, whereas we used Palmer and Parker's mobility to access mobility. Implant breakage, screw cut, and nonunion were considered as parameters of osteosynthesis failure. At the same time, hemiarthroplasty failure was defined as two or more recurrent dislocation, aseptic loosening, periprosthetic fracture, and infection. Results:  In the first three postoperative months, the mean score of the hemiarthroplasty group was reported as 74.44±8.480, which was comparatively high than the osteosynthesis group (66.44±8.520). After six months, this score reached 80.12±7.005 in the hemiarthroplasty group and reached its maximum of 92.14±7.125. After the first three months, the increment ratio was relatively slow with six ratios, but in the last visit, we observed a sudden increase in score in both groups. Regarding Palmer and Parker's mobility score, the hemiarthroplasty group reflected better outcomes than the osteosynthesis group. Conclusion: Our study concluded that management of displaced femoral neck fracture with osteosynthesis revealed a high probability of nonunion, screw cutout complications and enhanced the risk of reoperation. Patients treated with osteosynthesis showed delay rehabilitation.

MODUS OPERANDIIN ASSESSING BIOMASS AND CARBON IN RUBBER PLANTATIONS UNDER VARYING CLIMATIC CONDITIONS

2013 ◽  
Vol 50 (1) ◽  
pp. 40-58 ◽  
Author(s):  
E. S. MUNASINGHE ◽  
V. H. L. RODRIGO ◽  
U. A. D. P. GUNAWARDENA
Keyword(s):  
Rubber Tree ◽  
Rural Poverty ◽  
Growth Conditions ◽  
Climatic Conditions ◽  
Percentage Error ◽  
Carbon Trading ◽  
Average Growth ◽  
Allometric Models ◽  
The Mean ◽  
Simple Growth

SUMMARYIn addition to latex and timber, the rubber tree is useful in the alleviation of rural poverty and also in the mitigation of climate change through fixing atmospheric CO2as biomass. For developing any rubber-based carbon projects, protocols for quantifying biomass and carbon fixed are required. In this context, the present study was aimed at building up allometric models using simple growth indicators (i.e. tree diameter and total height) to assess the timber, biomass and carbon in rubber trees and also to quantify their ontogenetic variation under average growth conditions in two major climatic regimes (i.e. wet and intermediate) of Sri Lanka. All models developed were in the accuracy level of over 88%. The mean absolute percentage error in the validation of allometric models was only 12.9% for timber and less than 5% for biomass and carbon. Under average growth conditions, 1 ha of rubber could produce 208 m3timber, 191 MT biomass and fix 78 MT carbon during its 30-year lifespan in the wet zone and ca. 16% lesser values in the intermediate zone. The applicability of the findings in carbon trading is discussed.

scholarly journals Noise-driven growth rate gain in clonal cellular populations

2016 ◽  
Vol 113 (12) ◽  
pp. 3251-3256 ◽  
Author(s):  
Mikihiro Hashimoto ◽  
Takashi Nozoe ◽  
Hidenori Nakaoka ◽  
Reiko Okura ◽  
Sayo Akiyoshi ◽  
...  
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Single Cell ◽  
Single Cells ◽  
Population Level ◽  
Growth Conditions ◽  
Cell Dynamics ◽  
Generation Times ◽  
Complex Population ◽  
The Mean

Cellular populations in both nature and the laboratory are composed of phenotypically heterogeneous individuals that compete with each other resulting in complex population dynamics. Predicting population growth characteristics based on knowledge of heterogeneous single-cell dynamics remains challenging. By observing groups of cells for hundreds of generations at single-cell resolution, we reveal that growth noise causes clonal populations of Escherichia coli to double faster than the mean doubling time of their constituent single cells across a broad set of balanced-growth conditions. We show that the population-level growth rate gain as well as age structures of populations and of cell lineages in competition are predictable. Furthermore, we theoretically reveal that the growth rate gain can be linked with the relative entropy of lineage generation time distributions. Unexpectedly, we find an empirical linear relation between the means and the variances of generation times across conditions, which provides a general constraint on maximal growth rates. Together, these results demonstrate a fundamental benefit of noise for population growth, and identify a growth law that sets a “speed limit” for proliferation.

scholarly journals Interactive effects of temperature and light during deep convection: a case study on growth and condition of the diatom Thalassiosira weissflogii

2014 ◽  
Vol 72 (6) ◽  
pp. 2061-2071 ◽  
Author(s):  
B. Walter ◽  
J. Peters ◽  
J. E. E. van Beusekom ◽  
M. A. St. John
Keyword(s):  
Primary Production ◽  
Deep Convection ◽  
Growth Conditions ◽  
Interactive Effects ◽  
Light Conditions ◽  
Thalassiosira Weissflogii ◽  
Pulsed Light ◽  
Low Light ◽  
Chl A ◽  
The North

Abstract Aim of this study was to expose phytoplankton to growth conditions simulating deep winter convection in the North Atlantic and thereby to assess changes in physiology enabling their survival. Growth rate, biochemical composition, and photosynthetic activity of the diatom Thalassiosira weissflogii were determined under two different light scenarios over a temperature range of 5–15°C to simulate conditions experienced by cells during winter deep convection. These metrics were examined under a low light scenario (20 µmol m−2 s−1, 12/12 h light/dark), and compared with a scenario of short light pulses of a higher light intensity (120 µmol m−2 s−1, 2/22 h light/dark). Both experimental light conditions offered the same daily light dose. No growth was observed at temperatures below 8°C. Above 8°C, growth rates were significantly higher under low light conditions compared with those of short pulsed light exposures, indicating a higher efficiency of light utilization. This could be related to (i) a higher content of Chl a per cell in the low light trial and/or (ii) a more efficient transfer of light energy into growth as indicated by constantly low carbohydrate levels. In contrast, pulsed intense light led to an accumulation of carbohydrates, which were catabolized during the longer dark period for maintaining metabolism. Light curves measured via Chl a fluorescence indicated low light assimilation for the algae exposed to short pulsed light. We postulate that our trial with short light pluses did not provide sufficient light to reach full light saturation. In general, photosynthesis was more strongly affected by temperature under pulsed light than under low light conditions. Our results indicate that model estimates of primary production in relation to deep convection, which are based on average low light conditions, not considering vertical transportation of algae will lead to an overestimation of in situ primary production.

Some dynamical effects of heat on a turbulent boundary layer

1970 ◽  
Vol 40 (2) ◽  
pp. 361-384 ◽  
Author(s):  
C. I. H. Nicholl
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Mechanical Energy ◽  
Turbulent Energy ◽  
Strong Discontinuity ◽  
Sudden Increase ◽  
Boundary Layer Turbulence ◽  
Heated Air ◽  
Order Of Magnitude ◽  
The Mean

The dynamical effects of a sudden increase of as much as 100°C in boundary temperature upon fully turbulent boundary layers at low Reynolds numbers in air have been investigated in a wind tunnel. A section of the floor or the roof of the tunnel could be heated, so that the rate of working of gravitational forces on the turbulence could be made to represent either a gain or a loss of turbulent mechanical energy. Techniques of hot-wire anemometry were employed which enabled the instantaneous temperature and the instantaneous velocity to be measured simultaneously at a point in the non-homogeneous turbulent flow field.In the case of a strong discontinuity in the floor temperature, a fine-scale convective structure developed from the highly unstable interface between the heated air just above the surface and the turbulent boundary layer; and the motion in this region was sufficiently vigorous that the mean pressure in the vicinity of the floor was reduced and a local wall jet was generated. The deduced pressure distribution is regarded as evidence of coupling between the free and forced convection modes which may lead to a series of local wall jets downstream of the discontinuity.In the case of a strong discontinuity in the roof temperature, the interface between the heated air and the turbulent boundary layer was stable; and the boundary-layer turbulence, acting to spread this stable gradient over the vertical extent of the boundary layer, was required to do work against the gravitational field. A rate of working against gravity which was an order of magnitude less than the rate of supply of turbulent energy from the mean shear proved sufficient to suppress the turbulence in a very short time.

scholarly journals Quartz-in-garnet barometry constraints on formation pressures of eclogites from the Franciscan Complex, California

2022 ◽  
Vol 177 (1) ◽  
Author(s):  
Miguel Cisneros ◽  
Whitney M. Behr ◽  
John P. Platt ◽  
Robert Anczkiewicz
Keyword(s):  
Growth Conditions ◽  
The Other ◽  
Garnet Growth ◽  
Bulk Rock ◽  
Rock Composition ◽  
Temperature Variations ◽  
Franciscan Complex ◽  
The Mean ◽  
Santa Catalina Island ◽  
Structural Levels

AbstractDetermining pressure and temperature variations between high-pressure/low-temperature (HP–LT) eclogite blocks is crucial for constraining end-member exhumation models; however, it has historically been challenging to constrain eclogite pressures due to the high variance associated with this bulk-rock composition. In this work, we utilize quartz-in-garnet elastic barometry to constrain formation pressures of eclogites from the northern (Junction School, Ring Mountain, Jenner Beach) and southern Franciscan Complex (Santa Catalina Island). Multiple eclogite blocks from Jenner Beach are analyzed, and a single eclogite from the other localities. By comparing garnet growth conditions from within a single outcrop and between distinct outcrops, we evaluate the local and regional spatial distribution of P conditions recorded by eclogites. We compare the mean, median, and max pressures between different garnet zones and eclogites. Pressures sometimes exhibit systematic changes across garnet zones; however, some eclogites exhibit no systematic pressure variations across garnet zones. Pressures from northern Franciscan eclogites range from $$\sim $$ ∼ 1.4–1.8 GPa, at an estimated temperature of 500 $$^{\circ }$$ ∘ C; pressures from the Catalina eclogite range from $$\sim $$ ∼ 1.2–1.5 GPa, at an estimated temperature of 650 $$^{\circ }$$ ∘ C. Mean and maximum pressures of different eclogites from the northern Franciscan exhibit negligible differences (< 0.1 GPa). The results are inconsistent with models that propose exhumation of metamorphic blocks from different structural levels, and suggest that now exposed HP–LT eclogites from the northern Franciscan Complex may represent rocks that were coherently underplated, and exhumed from similar structural levels.

scholarly journals A reference sample of face-on bulgeless galaxies

2019 ◽  
Vol 485 (1) ◽  
pp. 1477-1487 ◽  
Author(s):  
I D Karachentsev ◽  
V E Karachentseva
Keyword(s):  
Reference Sample ◽  
Axial Ratio ◽  
Host Galaxy ◽  
Low Light ◽  
Morphological Composition ◽  
The Face ◽  
Projection Effect ◽  
The Mean ◽  
Absolute Magnitudes ◽  
Moderate Mass

Abstract We present a list of 220 face-on, almost bulgeless galaxies assumed to be counterparts to the objects from the Reference Flat Galaxy Catalogue (RFGC). We selected the Sc-, Scd-, and Sd-type galaxies according to their apparent axial ratio log(r25) < 0.05 and major standard angular diameter log(d25) > 0.90 as defined in HyperLEDA. The sample objects are restricted by the radial velocity $V_{\mathrm{ LG}} \lt 10\, 000$ km s−1 and a declination of above –30 deg. The morphological composition of our sample is quite similar to that of RFGC. We notice the following common properties of face-on bulgeless galaxies. About half of them have bar-like structures occurring in the whole range of the absolute magnitudes of galaxies: from −17 to −22 mag. An essential part of our sample (27–50 per cent) exhibit distorted spiral patterns. The galaxies do not show significant asymmetry in numbers of the ‘S’- and ‘Z’-like spin orientation. The mean (pseudo-)bulge-to-total mass ratio for the sample is estimated as 0.11. Due to a negligible internal extinction, low-light background, and small projection effect, the face-on Sc–Sd discs are suitable objects to recognize their central nuclei as moderate-mass BH candidates. About 40–60 per cent of the galaxies have distinct unresolved nuclei, and their presence steeply depends on the luminosity of the host galaxy.

scholarly journals Post-monsoon waterlogging-associated upsurge of cholera cases in and around Kolkata metropolis, 2015

2019 ◽  
Vol 147 ◽  
Author(s):  
Asish K. Mukhopadhyay ◽  
Alok K. Deb ◽  
Goutam Chowdhury ◽  
Falguni Debnath ◽  
Prosenjit Samanta ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Heavy Rainfall ◽  
Demographic Characteristics ◽  
Sudden Increase ◽  
Cholera Outbreak ◽  
Enteric Diseases ◽  
Stool Specimens ◽  
The Mean ◽  
Bacteriological Laboratory ◽  
Structured Questionnaire

AbstractThe Infectious Diseases and Beliaghata General Hospital, Kolkata, India witnessed a sudden increase in admissions of diarrhoea cases during the first 2 weeks of August 2015 following heavy rainfall. This prompted us to investigate the event. Cases were recruited through hospital-based surveillance along with the collection of socio-demographic characteristics and clinical profile using a structured questionnaire. Stool specimens were tested at bacteriological laboratory of the National Institute of Cholera and Enteric Diseases (NICED), Kolkata. Admission of 3003 diarrhoea cases, clearly indicated occurrence of outbreak in Kolkata municipal area as it was more than two standard deviation of the mean number (911; s.d. = 111) of diarrhoea admissions during the same period in previous 7 years. Out of 164 recruited cases, 25% were under-5 children. Organisms were isolated from 80 (49%) stool specimens. Vibrio cholerae O1 was isolated from 50 patients. Twenty-eight patients had this organism as the sole pathogen. Among 14 infants, five had cholera. All V. cholerae O1 isolates were resistant to nalidixic acid, followed by co-trimoxazole (96%), streptomycin (92%), but sensitive to fluroquinolones. We confirmed the occurrence of a cholera outbreak in Kolkata during August 2015 due to V. cholerae O1 infection, where infants were affected.

Sign in / Sign up

Export Citation Format

Share Document