abstract. the purpose of this study was to investigate vegetation dynamics and range conditions considering the climatic conditions and soil properties in haftooman, khoor and biabanak deserts, iran. for this purpose, after determining vegetation types and the associated species, the type of rangeland utilization, grazing season, the livestock type, the other relevant information, vegetation da...

We introduce the successive Hitting Set model, where the set system is not given in advance but a set generator produces the sets that contain a specific element from the universe on demand. Despite incomplete knowledge about the set system, we show that several approximation algorithms for the conventional Hitting Set problem can be adopted to perform well in this model. We describe, and exper...

We study a geometric hitting set problem involving unirectional rays and curves in the plane. We show that this problem is hard to approximate within a logarithmic factor even when the curves are convex polygonal x-monotone chains. Additionally, it is hard to approximate within a factor of 76 even when the curves are line segments with bounded slopes. Lastly, we demonstrate that the problem is ...

This paper studies a combination problem of parallel machine scheduling and the covering problem. We say a combinatorial optimization problem is a covering problem if it minimizes a linear objective function under some constraints and the variables are binary. The covering problem generalizes many classic combinatorial optimization problems, e.g. the shortest path problem, the vertex cover prob...

INTRODUCTION WHO now recommends test-based management of malaria (TBMM) across all age-groups. This implies artemisinin-based combination treatment (ACT) should be restricted to rapid diagnostic test (RDT)-positive cases. This is a departure from what caregivers in rural communities have been used to for many years. METHODS We conducted a survey among caregivers living close to 32 health cent...

land cover map is important for many urban planning and management activities. in this study, in order to produce land cover map of arak city, digital image of liss-iii scanner acquired on 16 june 2006 were employed. first of all, geometric correction with rmse 0.58 pixel was applied. considering the mountainous condition of the study area, topographic correction was applied to the image. in su...

Land degradation is a major danger which restricting different areas of Iran. Systematic description of the environmentfor detection of environmental changes and the human-related causes and responses is essential in land cover changestudy. Use of land cover data allow detection of where certain changes occur, what type of change, as well as how theland is changing. Existing systems for classif...

To determine the suitable indices for vegetation cover and production assessment based on the remote sensing data, simultaneous digital data with field data belonging to the spring rangeland of the Semirom-Isfahan province were analyzed. During two years of monitoring the annual, grass, forb, and shrub vegetation cover and the total production data from 86 were collected. The Global Positioning...

Brown spot disease caused by Alternaria alternata (Fr.: Fr.) Keissl is a serious problem forproduction of tangerines and tangerine hybrids in Iran. The Tangerine pathotype causes brownspot disease on young leaves and immature fruits of limited varieties of mandarins and tangerines(Citrus. reticulata Blanco). Specificity in the interaction between tangerine and the pathogen isdetermined by a hos...