Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

2019 ( 10 )

2018 ( 18 )

2017 ( 21 )

2016 ( 37 )

Custom range...

Search Results: 1 - 10 of 3129 matches for " HAMID JALILVAND "
All listed articles are free for downloading (OA Articles)
Page 1 /3129
Display every page Item
Earthworms as Ecosystem Engineers and the Most Important Detritivors in Forest Soils
Yahya Kooch,Hamid Jalilvand
Pakistan Journal of Biological Sciences , 2008,
Abstract: Earthworms are considered as soil engineers because of their effects on soil properties and their influence on the availability of resources for other organisms, including microorganisms and plants. However, the links between their impacts on the soil environment and the resulting modification of natural selection pressures on engineer as well as on other organisms have received little attention. Earthworms are known to have a positive influence on the soil fabric and on the decomposition and mineralization of litter by breaking down organic matter and producing large amounts of fasces, thereby mixing litter with the mineral soil. Therefore, they play an important part in changes from one humus from to another according to forest succession patterns. Consequently, they are also expected to be good bio-indicators for forest site quality and are thus useful when planning forest production improvement. Earthworm`s populations are as indicator that in exploited regions is destruction indicator and reclamation plans is nature return indicator. In this study we summarized the current knowledge in relation to earthworm`s ecology in forest soils as ecosystem engineers.
Marginal Effect of Forest Road on Alder Trees (Case Study: Darab Kola Forest, Mazandaran Province, Iran)
Seyed Ataollah Hosseini,Hamid Jalilvand
Pakistan Journal of Biological Sciences , 2007,
Abstract: Forest road is one of the most important ways to access the forest and its own activities. It should have some standard qualities and also had the list harm for nature. One of the most important qualities of forest road is limited of two sides to developing of natural forest. Alder tree is the first kind of trees that grows in northern forest of Iran closed to the constructed roads. This research was done in Mazandaran forest (Darab Kola district) to evaluate how Alder grows in the two side margins of roads. Twenty half plot (upper and lower road margins) with a size of 1000 m2 in one kilometer length of this road was selected and twenty face to face Alder trees closed to the road were sampled to take two cores in a face and back of road at the DBH level. After analyzing the data with a simple variance and comparing annual rings (curves), diameter, height and growth by simple and joint t-test, the results show that there is no significant difference between growing in upwards and downwards of road and also between diameter and height of tree in two sides of road. Most diameter distribution classes of trees were in a 15-20 cm. To consider more about this matter, study of different width and slopes of forest roads in a various forest stands was proposed.
Physical Soil Properties and Slope Treatments Effects on Hydraulic Excavator Productivity for Forest Road Construction
Aidin Parsakho,Seyed Ataollah Hosseini,Hamid Jalilvand,Majid Lotfalian
Pakistan Journal of Biological Sciences , 2008,
Abstract: Effects of moisture, porosity and soil bulk density properties, grubbing time and terrain side slopes on pc 220 komatsu hydraulic excavator productivity were investigated in Miana forests road construction project which located in the northern forest of Iran. Soil moisture and porosity determined by samples were taken from undisturbed soil. The elements of daily works were measured with a digital stop watch and video camera in 14 observations (days). The road length and cross section profiles after each 20 m were selected to estimate earthworks volume. Results showed that the mean production rates for the pc 220 komatsu excavators were 60.13 m3 h-1 and earthwork 14.76 m h-1 when the mean depth of excavation or cutting was 4.27 m3 m-1, respectively. There was no significant effects (p = 0.5288) from the slope classes` treatments on productivity, whereas grubbing time, soil moisture, bulk density and porosity had significantly affected on excavator earthworks volume (p < 0.0001). Clear difference was showed between the earthwork length by slope classes (p = 0.0060). Grubbing time (p = 0.2180), soil moisture (p = 0.1622), bulk density (p = 0.2490) and porosity (p = 0.2159) had no significant effect on the excavator earthworks length.
The Use of Principal Component Analysis in Studying Physical, Chemical and Biological Soil Properties in Southern Caspian Forests (North of Iran)
Yahya Kooch,Hamid Jalilvand,Mohammad Ali Bahmanyar,Mohammad Reza Pormajidian
Pakistan Journal of Biological Sciences , 2008,
Abstract: This research was conducted in Khanikan forests located in lowland of Mazandaran province (North of Iran). Eighteen profiles were dug and several chemical, physical and biological soil properties were investigated. The soil properties evaluated were soil pH, bulk density, saturation moisture content, electrical conductivity, organic carbon, total nitrogen, cation exchangeable capacity, available phosphorous, soil texture, calcium carbonate content, number and biomass of earthworms, litter carbon and litter nitrogen. Principal Component Analysis (PCA) was used to identify the variation of soil properties. PCA, a technique which reduces the dimensionality of multivariate data by removing Interco relations among variables, has a number of useful applications in forest researches. The results showed significant relationships between some soil factors with PC1 and PC2 axes, also, among different soil factors, the distribution of forest types was most strongly controlled with some soil characteristics such as acidity, bulk density, texture, phosphorous, organic carbon, total nitrogen and cation exchangeable capacity.
Application of Two Way Indicator Species Analysis in Lowland Plant Types Classification
Yahya Kooch,Hamid Jalilvand,Mohammad Ali Bahmanyar,Mohammad Reza Pormajidian
Pakistan Journal of Biological Sciences , 2008,
Abstract: A TWINSPAN classification of 60 sample plots from the Khanikan forest (North of Iran) is presented. Plant types were determined from field observations and sample plot data arranged and analyzed in association tables. The types were defined on the basis of species patterns of presence, absence and coverage values. Vegetation was sampled with randomized-systematic method. Vegetation data including density and cover percentage were estimated quantitatively within each quadrate and using the two-way indicator species analysis. The objectives of the study were to plant type`s classification for Khanikan lowland forest in North of Iran, Identification of indicator species in plant types and increase our understanding in regarding to one of Multivariate analysis methods (TWINSPAN). Five plant types were produced for the study area by TWINSPAN, i.e., Menta aquatica, Oplismenus undulatifolius, Carex grioletia, Viola odarata and Rubus caesius. Therefore, at each step of the process, the program identifies indicator species that show strongly differential distributions between groups and so can severe to distinguish the groups. The final result, incorporating elements of classification can provide a compact and powerful summary of pattern in the data set.
Vegetative characteristics of Avicennia marina on the artificial inlet
Biodiversitas , 2012,
Abstract: The purpose of this project is attempt to ecological development of Avicennia marina in hyper saline condition. During 2001 and 2002 a restoration mangrove project " planting A. marina in artificial inlet in Bushehr Province, Iran" was carried out in Agriculture &Natural resources research center of Bushehr province in Sabkha lands. Some the vegetative characteristics of such as height, diameter and crown diameter in two aspects were recorded in 2012. To investigate physico-chemical properties of soil were taken in inside and outside of inlet and were analyzed: salinity, soil acidity, potassium, phosphorus, nitrogen, texture of soil were measured. Both of treatments were analyzed by T test in SAS Software. The result showed that a different significant between inside and outside of Inlet in soil acidity, electrical conductivity, potassium content and sand and clay percent. But were not different significant in N and P. After ten years halophyte plants such as: Salicornia herbacea and Halocnemum strobilaceum and animals such as: mudskippers were observed into this area. Site conditions have an influence on the growth of seedling, which shows a different growth in the outside and inside of artificial inlets.
Tree-Ring Growth Response of Common Ash ( Fraxinus excelsior L.) to Climatic Variables Using Multiple Regressions
H. Jalilvand
Journal of Science and Technology of Agriculture and Natural Resources , 2008,
Abstract: This study was down in Forest Park of Noor. In order to determination of tree ring response to climatic variations, 35 cores were taken from dominant natural stand of common ash (Fraxinus excelsior L.). The guide of this study was finding which climatic variables are effective in the ring width growth of ash in current growing year and previous years (one, two and three years before current growing year) by multiple regression models at the North of IR-Iran. Totally, 85 annually, monthly seasons and seasonal growth climatic variations of precipitation, temperature, heat index, evapotranspiration and water balance were analyzed. The best multiple regression models were explained 83 percent of total variance of the growth of common ash. The results show that the growth of common ash was related to the previous year's climatic variations than that of the current year. The most effective role of climatic variations was due to the first and second preceding years (55%). Evapotranspiration of July and September, and precipitation of May in the second and precipitation of March in the third previous years, all were positively affected the growth of this species. This study revealed that ash is interested in warmer condition on early and middle of seasonal growth in present of available humid, and precipitation in the months of early growing season (Ordibehesht-Khordad of two previous years).
Hearing Aid Selection for Severe to Profound Hearing Impairment (Part 2)
Leyla Jalilvand karimi
Audiology , 1993,
Abstract: Hearing aid selection as the first step in modifying the hearing loss is a critical point . people with severe to profound hearing loss need special consideration. In order to determine the amount of gain and output of hearing aids, some formula are presented. Although most of these formula are planned for mild to moderate hearing loss, they are used for severe to profound hearing losses. POGO method is one of these formula. This method, based on halving the hearing threshold, is not suitable for profound hearing loss. There are some considerations in revising this method for severe to profound hearing loss and its name has changed to POGO II, too.
The Political Participation and Government Size
Neda Samiei,Mohammad Reza Jalilvand
Canadian Social Science , 2011,
Abstract: : This paper analyzes the effect of political participation on government size. First, the paper extends the model proposed by Mueller and Stratmann, which considers relation of political participation and government size. Second, we estimate this model with another index like democracy, voice and accountability, and Civil liberties index as political participation index. This model points that any increase in political participation is generally found to raise government size; however this increasing effect is low. Also, other considered indicators have a significant effect on government size. Our case study is the Asia and Pacific Ocean countries in during 2000 to 2008. Findings showed that when participation rate, democracy index, and voice and accountability index increase one percent, government size increases 0.065, 1.30, and 3.19 percent, respectively. Additionally, when civil liberties increases one percent, government size declines 1.29 percent. The paper provides a small expansion of Mueller and Stratmann model that considers the effect of the overall concept of political participation on government size by using indexes like democracy, voice and accountability, and Civil liberties index. Key words: Government Size; Political participation; Generalized Method of Moments (GMM) Résumé: Cet article analyse l'effet de la participation politique sur la taille du gouvernement. Tout d'abord, l'article étend le modèle concernant la participation politique et la taille du gouvernement proposé par Mueller et Stratmann. Ensuite, il évalue ce modèle avec d’autres indices comme la démocratie, le droit de parler et la responsabilité, et des indices de libertés civiles en tant que l'indice de la participation politique. Ce modèle indique que toute augmentation de la participation politique contribue généralement à élargir la taille du gouvernement, mais cet effet est faible. En outre, d'autres indicateurs estimés ont un effet significatif sur la taille du gouvernement. Notre étude de cas est menée sur les pays en Asie et dans l’océan pacifique au cours de 2000 à 2008. Les résultats ont montré que lorsque le taux de participation, l'indice de démocratie et l’indice du droit de parler et de la responsabilité augmente de 1%, la taille du gouvernement élargit de 0.065%, 1.30%, et 3.19%t, respectivement. Par contre, lorsque les libertés civiles augmente de 1%, la taille du gouvernement baisse de 1,291%. L’article fait une légère expansion du modèle de Mueller et Stratmann qui évalue l'effet de la notion globale de la participation politique sur la taille
The Effects of Demographic Characteristics on Employees’ Motivation to Participate in the In-Service Training Courses based on the Modified Expectancy Theory
Mohammad Reza Jalilvand,Farhad Ebrahimabadi
Canadian Social Science , 2011, DOI: 10.3968/j.css.1923669720110703.024
Abstract: Modified expectancy theory provided a useful framework for assessing employee behavior in learning, decision-making, and motivation. The purpose of current study is to determine the effects of demographic characteristics on employees’ motivation based on the modified expectancy theory. Population was the employees of National Iranian Oil Products Distribution Company in Isfahan and Kurdistan. Multivariate analysis of variance (MANOVA) was used for data analysis. Finding reveals that the type of employment influences expectancy, intrinsic instrumentality, extrinsic valence, and motivation of employees for participating in the in-service training courses in the oil industry setting. Additionally, employee’s education influenced widely extrinsic instrumentality. Key words: Modified expectancy theory; Demographic characteristics; Motivation Résumé: La théorie de l'espérance de modification/de la mise à jour a fourni un cadre utile pour évaluer le comportement des employés dans l'apprentissage, la prise de décision, et la motivation. Le but de l'étude présente est de déterminer les effets des caractéristiques démographiques sur la motivation des salariés fondée sur la théorie de l'espérance de modification. Les sujets d'étude sont les employés de la Compagnie nationale iranienne de la distribution des produits pétroliers à Ispahan et Kurdistan. L'analyse multivariée de la variance (ANMDVA) a été utilisée pour l'analyse des données. Le résultat révèle que le type d'emploi influe sur l'espérance, l'instrumentalité intrinsèque, la valence extrinsèque, et la motivation des employés à participer aux cours de formation en service dans le cadre de l'industrie pétrolière. De plus, la formation des employés a une grande influence sur l'instrumentalité extrinsèque. Mots-clés: Théorie de l'espérance de modification; Caractéristiques démographiques; Motivation
Page 1 /3129
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.