Biomass and nutrients in Great Lakes – St. Lawrence forest species: implications for whole-tree and conventional harvest

1987 ◽  
Vol 17 (3) ◽  
pp. 210-218 ◽  
Author(s):  
O. Q. Hendrickson ◽  
D. M. Burgess ◽  
L. Chatarpaul
Keyword(s):  
Great Lakes ◽  
Large Diameter ◽  
Small Diameter ◽  
Nutrient Concentrations ◽  
Nutrient Contents ◽  
Stem Wood ◽  
N Removal ◽  
Shade Tolerant Species ◽  
Pinus Spp ◽  
Whole Tree

Total aboveground biomass and nutrient contents were measured in a mixed conifer and hardwood stand in Ontario. Removal of woody stems > 9 cm dbh (conventional harvest) yielded 138 000 kg/ha; removal of essentially all aboveground woody material (whole-tree harvest) yielded an additional 52 000 kg/ha, a 38% increase. Whole-tree harvest increased N removal by 191 kg/ha (132%). Logging slash on the conventional harvest plot added 163 kg N/ha to the forest floor. Nutrients within various biomass components of seven tree species were compared. Pinusresinosa Ait., the dominant conifer, produced the greatest amount of biomass per unit mass of nutrient, combining low nutrient concentrations with a high proportion of biomass in stem wood. Populustremuloides Michx., the dominant hardwood, had high proportions of cation-rich bark but had a lower whole-tree N concentration than most other species. High nutrient contents in Abiesbalsamea (L.) (Mill.) and Piceaglauca (Moench) Voss were related to large amounts of fine branches and foliage. Compared with the dominants, shade-tolerant species had less differences in nutrient concentrations between small and large diameter portions of stems and branches, suggesting a limited capacity for retranslocation. Abiesbalsamea was particularly poor at conserving K. A conventional harvest often leaves small diameter stems of species (Abiesbalsamea, Acerrubrum L.) that accumulate large amounts of nutrients and that may be poorly adapted to low throughfall cation inputs and high light intensities following overstory removal. Replacement of stands of Pinus spp. by Populus spp. represents a less efficient use of site nutrient capital in that the latter species produce less biomass per unit nutrient retained in permanent aboveground tissues. Whole-tree harvesting on nutrient-poor sites in the Great Lakes – St. Lawrence forest may lead to establishment of aspen stands of low productivity.

Differences in the brain stem terminations of large- and small-diameter vestibular primary afferents

1995 ◽  
Vol 74 (3) ◽  
pp. 1362-1366 ◽  
Author(s):  
J. A. Huwe ◽  
E. H. Peterson
Keyword(s):  
Brain Stem ◽  
Large Diameter ◽  
Small Diameter ◽  
Movement Control ◽  
Three Dimensions ◽  
Significant Shift ◽  
Axon Diameter ◽  
Vestibular Complex ◽  
The Brain ◽  
Adjacent Brain

1. We visualized the central axons of 32 vestibular afferents from the posterior canal by extracellular application of horseradish peroxidase, reconstructed them in three dimensions, and quantified their morphology. Here we compare the descending limbs of central axons that differ in parent axon diameter. 2. The brain stem distribution of descending limb terminals (collaterals and associated varicosities) varies systematically with parent axon diameter. Large-diameter afferents concentrate their terminals in rostral regions of the medial/descending nuclei. As axon diameter decreases, there is a significant shift of terminal concentration toward the caudal vestibular complex and adjacent brain stem. 3. Rostral and caudal regions of the medial/descending nuclei have different labyrinthine, cerebellar, intrinsic, commissural, and spinal connections; they are believed to play different roles in head movement control. Our data help clarify the functions of large- and small-diameter afferents by showing that they contribute differentially to rostral and caudal vestibular complex.

scholarly journals Elastic Modulus and Elasticity Ratio of Malignant Breast Lesions with Shear Wave Ultrasound Elastography: Variations with Different Region of Interest and Lesion Size

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1015
Author(s):  
Antonio Bulum ◽  
Gordana Ivanac ◽  
Eugen Divjak ◽  
Iva Biondić Špoljar ◽  
Martina Džoić Dominković ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Shear Wave ◽  
Large Diameter ◽  
Small Diameter ◽  
Shear Wave Elastography ◽  
Lesion Size ◽  
Ultrasound Elastography ◽  
Breast Lesions ◽  
Malignant Breast ◽  
The Impact

Shear wave elastography (SWE) is a type of ultrasound elastography with which the elastic properties of breast tissues can be quantitatively assessed. The purpose of this study was to determine the impact of different regions of interest (ROI) and lesion size on the performance of SWE in differentiating malignant breast lesions. The study included 150 female patients with histopathologically confirmed malignant breast lesions. Minimal (Emin), mean (Emean), maximal (Emax) elastic modulus and elasticity ratio (e-ratio) values were measured using a circular ROI size of 2, 4 and 6 mm diameters and the lesions were divided into large (diameter ≥ 15 mm) and small (diameter < 15 mm). Highest Emin, Emean and e-ratio values and lowest variability were observed when using the 2 mm ROI. Emax values did not differ between different ROI sizes. Larger lesions had significantly higher Emean and Emax values, but there was no difference in e-ratio values between lesions of different sizes. In conclusion, when measuring the Emin, Emean and e-ratio of malignant breast lesions using SWE the smallest possible ROI size should be used regardless of lesion size. ROI size has no impact on Emax values while lesion size has no impact on e-ratio values.

Analysis Influence of Pile Embedded Depth and Diameter on Pile Tip Resistance

2013 ◽  
Vol 353-356 ◽  
pp. 459-462
Author(s):  
Ying Jie Zheng ◽  
Bin Fang ◽  
Lian Xiang Li
Keyword(s):  
Large Diameter ◽  
Small Diameter ◽  
Stiffness Ratio ◽  
Initial Stiffness ◽  
Tip Resistance

Pile tip absolute settlement curves and relative settlement curves of several working cases were analyzed. It is found that load-settlement curve characteristic related to the selection standard. The tip resistance initial stiffness of each case was analyzed. Results show that the small diameter pile has higher initial stiffness than large diameter pile, embedded depth has little influence on initial stiffness ratio, but increment of initial stiffness is linear with embedded depth growth.

Nutrient losses under simulated rainfall from pasture plots in the Great Lakes District, New South Wales

Soil Research ◽  
2009 ◽  
Vol 47 (6) ◽  
pp. 555 ◽  
Author(s):  
Michael G. Jones ◽  
R. Willem Vervoort ◽  
Julie Cattle
Keyword(s):  
Great Lakes ◽  
New South ◽  
New South Wales ◽  
Nutrient Concentrations ◽  
Storm Event ◽  
Simulated Rainfall ◽  
Nutrient Losses ◽  
Major Pathway ◽  
Nutrient Runoff ◽  
South Wales

Understanding the process by which nutrients and solids enter waterways from pastures in the Great Lakes district, New South Wales, Australia, may assist in maintaining water quality to ensure ongoing environmental and economic sustainability of the region. Rainfall simulations, using a 100-year return storm event, were conducted to determine nutrient and suspended solid concentrations in the runoff of 8 pasture sites in 3 of the catchments in the district. On 5 of the 8 sites, considerable concentrations of N or P were mobilised during the simulated rainfall event, but average nutrient concentrations and total loads across all sites were relatively low and similar to other studies of nutrient runoff from pastures. In addition, low runoff coefficients indicated that runoff is probably not the major pathway for nutrient losses from pasture in this area. Overall, rainfall runoff responses at the sites were similar in the 3 catchments. In contrast, the results suggest that, despite generating more runoff, the sites in the Wang Wauk catchment generated less nutrients in runoff than the sites in the Wallamba and Myall catchments. There was no difference in total suspended solids loads for the sites analysed by catchment. Relationships between soil physical and chemical characteristics and total nutrients loads or cumulative runoff were not strong.

New method of poultry selection

2021 ◽  
pp. 61-66
Author(s):  
E. Rehleckaya ◽  
A. Dymkov ◽  
L. Lazarets ◽  
A. Maltsev
Keyword(s):  
Egg Production ◽  
Initial Period ◽  
Large Diameter ◽  
Small Diameter ◽  
Live Weight ◽  
Individual Variability ◽  
Egg Laying ◽  
New Method ◽  
Egg Diameter ◽  
Correlation Rate

Purpose: Install the influence of the «small diameter of the egg» on the living mass and the reproductive qualities of chickens of meat crosses and the quail of meat breeds.Materials and methods. The selection was carried out along egg production and mass of eggs and additionally on the average small diameter of 5 eggs by value of ≥0.5σ from the average for the herd, while the evaluation on the basis of the «small diameter of the egg» was carried out in chickens aged 238 days of life, quails — 70 days of life. Calculated the average for each female and the average for the herd. For further reproduction, chickens carrying eggs with a small egg diameter ≥0.5σ from the average for the herd. Studies were held in SibNIP on quail and on the courses.Results. In the initial period of the egg laying, the individual variability of the small diameter of the egg — more than 10% (in the future, the figure decreased). The close correlation rate of the small egg diameter in the first half of the egg laying with such at the end of the bird's operation period was revealed. It has been established that the large diameter of the egg has a positive reliable connection with a lively mass, but negative with egg production. The reliable correlation rate of the small diameter of the egg with a live weight at a 42-day age, as well as with the derivation of eggs. The inheritance coefficients of the small diameter of the egg are comparable to the inheritance coefficients of the mass of eggs and significantly exceed those for a large diameter of the egg. The selection according to the small diameter of the eggs by ≥0.5σ from the average for the herd led to the fact that the chickens of the experimental groups reliably exceeded the live weight in the SB level of 1.57%, in the line G8 — by 1.35%. The superiority of a lively mass of quail of experienced groups was more pronounced than that of the chickens: the Pharaoh breed — by 4.15%, the Texas white breed is 4.22%. In relation to the derivation of eggs, a similar trend was traced. The derivation of eggs in quails of experienced groups was more than 4.59–4.98%; Country, respectively, 4.57–5.22%. Egg production of females of comparable groups of both chickens and quail was almost on the same level, and the difference was unreliable.Conclusion. It was established that a new method of breeding the poultry of the meat direction of productivity allows without decreasing egg production to increase the living mass of chickens of meat crosses by 1.5%, rewinds of meat breeds — by 4%, the derivation of eggs, respectively, by 4–5%. The method is intended for early prediction of females productivity during breeding selection.

Copolymer-Nanoparticles Mixture in a Cylindrical Pore

NANO ◽  
2017 ◽  
Vol 12 (04) ◽  
pp. 1750045
Author(s):  
Jun-Xing Pan ◽  
Yu-Qi Guo ◽  
Yu-Fang Han ◽  
Min-Na Sun ◽  
Jin-Jun Zhang
Keyword(s):  
Phase Transition ◽  
Electrical Conductivity ◽  
Polymer Nanocomposites ◽  
Diblock Copolymer ◽  
Large Diameter ◽  
Small Diameter ◽  
Confinement Effect ◽  
Cylindrical Pore ◽  
Disorder Phase Transition ◽  
Novel Structures

Computer simulation is carried out for investigating the effect of nanoparticles on diblock copolymer morphology under cylindrical confinement. The phase diagrams of polymer nanocomposites with nanoparticle-block wetting strength and concentration of nanoparticles are obtained in different nanopores. In small diameter nanopore, there is almost no influence of nanoparticles on the diblock copolymer morphology because of the stronger confinement effect; in middle diameter nanopore, the system can self-assemble into various novel structures due to the interaction between confinement effect and nanoparticles effect; in large diameter nanopore, due to the stronger effect of nanoparticles, a disorder-order-disorder phase transition occurs with the wetting strength and concentration of nanoparticles increasing. This result can be useful in designing new nanocomposites with advanced electrical conductivity and/or mechanical strength.

scholarly journals A model of tight junction function in central nervous system myelinated axons

2008 ◽  
Vol 4 (4) ◽  
pp. 307-317 ◽  
Author(s):  
Alexander Gow ◽  
Jerome Devaux
Keyword(s):  
Current Flow ◽  
Large Diameter ◽  
Small Diameter ◽  
Structural Features ◽  
Axonal Membrane ◽  
Flow Through ◽  
Saltatory Conduction ◽  
Gait Abnormalities ◽  
Low Capacitance ◽  
Speed And Accuracy

The insulative properties of myelin sheaths in the central and peripheral nervous systems (CNS and PNS) are widely thought to derive from the high resistance and low capacitance of the constituent membranes. Although this view adequately accounts for myelin function in large diameter fibers, it poorly reflects the behavior of small fibers that are prominent in many regions of the CNS. Herein, we develop a computational model to more accurately represent conduction in small fibers. By incorporating structural features that, hitherto, have not been simulated, we demonstrate that myelin tight junctions (TJs) improve saltatory conduction by reducing current flow through the myelin, limiting axonal membrane depolarization and restraining the activation of ion channels beneath the myelin sheath. Accordingly, our simulations provide a novel view of myelin by which TJs minimize charging of the membrane capacitance and lower the membrane time constant to improve the speed and accuracy of transmission in small diameter fibers. This study establishes possible mechanisms whereby TJs affect conduction in the absence of overt perturbations to myelin architecture and may in part explain the tremor and gait abnormalities observed in Claudin 11-null mice.

scholarly journals Study on Failure Plane of Bulk Solid in Squat Silos

2012 ◽  
Vol 6 (1) ◽  
pp. 33-37
Author(s):  
Changbing Chen
Keyword(s):  
Limit Equilibrium ◽  
Large Diameter ◽  
Small Diameter ◽  
Theoretical Method ◽  
Wall Pressure ◽  
Failure Plane ◽  
Limit Equilibrium Theory ◽  
Bulk Solid ◽  
Important Basis ◽  
Key Parameter

With the increasing volume demand of silos, squat silo diameters are bigger and bigger. However, present wall pressure computation methods are mostly based on small diameter silos. To solve this problem, systematical research on the wall pressure in squat silos is of great importance. For now, in the Chinese code the wall pressure computation methods are based on the limit equilibrium theory to be calculated, which define the orientation of the failure plane in the bulk solid within the silo. The rupture angle is a key parameter to silos’ wall pressure. Therefore the value and direction of rupture angle are researched by theoretical method in this paper, which has heavy significance and provide an important basis for the large diameter silo design.

scholarly journals Numerical Study of Plasmon Resonance Silver Nanoparticles Coated Polyvinyl Alcohol (PVA) using Bohren-Huffman-Mie Approximation

2016 ◽  
Vol 1 ◽  
Author(s):  
Dede Djuhana
Keyword(s):  
Silver Nanoparticles ◽  
Polyvinyl Alcohol ◽  
Numerical Study ◽  
Large Diameter ◽  
Small Diameter ◽  
Resonant Mode ◽  
Major Peak ◽  
Ag Nps ◽  
Quadrupole Mode ◽  
Minor Peak

<p class="TTPAbstract">In this study, we have investigated the LSPR spectra of the silver nanoparticles (Ag-NPs) coated by polyvinyl alcohol (PVA) by means of a numerical study using Bohren-Huffman-Mie (BHMie) approximation. The LSPR of Ag-NPs shifted to red-shift as the diameter size of Ag-NPs and the thickness of PVA increased. The peak of the LSPR spectra exponentially increased as the thickness increased. Interestingly, there have three characteristic of the LSPR spectra, small, intermediate, and large diameter. In small diameter, the dipole resonant mode contributed to the LSPR spectra while in large diameter, the LSPR spectra originated from the quadrupole resonant mode. In contrast to intermediate diameter, the LSPR spectra originated from the competition between the dipole and the quadrupole mode. For this reason, at small and large diameter the LSPR peak has one peak and increased then until a certain thickness showed constant. Different at intermediate diameter, the LSPR peak appeared more one peak with major peak increased then until a certain thickness trend to decrease and minor peak followed at small diameter behavior.</p>

scholarly journals Foraging loads of red wood ants:Formica aquilonia(Hymenoptera: Formicidae) in relation to tree characteristics and stand age

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2049 ◽  
Author(s):  
Heloise Gibb ◽  
Jon Andersson ◽  
Therese Johansson
Keyword(s):  
Large Diameter ◽  
Negative Relationship ◽  
Small Diameter ◽  
Resource Depletion ◽  
Foraging Efficiency ◽  
Stand Age ◽  
Resource Quality ◽  
Red Wood Ants ◽  
Wood Ants ◽  
Colony Level

Background.Foraging efficiency is critical in determining the success of organisms and may be affected by a range of factors, including resource distance and quality. For social insects such as ants, outcomes must be considered at the level of both the individual and the colony. It is important to understand whether anthropogenic disturbances, such as forestry, affect foraging loads, independent of effects on the quality and distribution of resources. We asked if ants harvest greater loads from more distant and higher quality resources, how individual efforts scale to the colony level, and whether worker loads are affected by stand age.Methods.First, we performed a fine-scale study examining the effect of distance and resource quality (tree diameter and species) on harvesting of honeydew by red wood ants,Formica aquilonia, in terms of crop load per worker ant and numbers of workers walking up and down each tree (ant activity) (study 1). Second, we modelled what the combination of load and worker number responses meant for colony-level foraging loads. Third, at a larger scale, we asked whether the relationship between worker load and resource quality and distance depended on stand age (study 2).Results.Study 1 revealed that seventy percent of ants descending trees carried honeydew, and the percentage of workers that were honeydew harvesters was not related to tree species or diameter, but increased weakly with distance. Distance positively affected load mass in both studies 1 and 2, while diameter had weak negative effects on load. Relationships between load and distance and diameter did not differ among stands of different ages. Our model showed that colony-level loads declined much more rapidly with distance for small diameter than large diameter trees.Discussion.We suggest that a negative relationship between diameter and honeydew load detected in study 1 might be a result of crowding on large diameter trees close to nests, while the increase in honeydew load with distance may result from resource depletion close to nests. At the colony level, our model suggests that very little honeydew was harvested from more distant trees if they were small, but that more distant larger trees continued to contribute substantially to colony harvest. Although forestry alters the activity and foraging success of red wood ants, study 2 showed that it does not alter the fundamental rules determining the allocation of foraging effort.

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