Harvesting of self-growing plants, like acanthus; from the down slopes of mountainous regions often causes disturbances to the appearance of the slopes if it is mowed intensively. These soil disturbances often occur with spring showers that accelerate soil erosion. On the other hand, the harvesting is inevitable because of acanthus clinical and sustenance uses and earning a livelihood for many local people who make a living with such crop in the harvesting seasons. So, as the spring season starts, the harvest of self growing plants becomes a usual phenomenon on the slopes in lower altitudes. The harvest of rooting plants as acanthus is in a way that makes pits on the ground and this may be agent of erosion when spring rain falls, specially, precipitation contact with plant germination in Iran. So, in this study, it has been tried to elucidate if the harvesting of acanthus makes erosion at every situation or reaching to erosion threshold needs to increase number of the harvesting in area unit as well as other location with more gradient and other characteristics. Research Methodology: In this survey has been taken into consideration the sediment producing in 16 plots with and without acanthus in the Viece Mountain, near Kermanshah city. Whereas, gradients and orientation are factors that play roles on erosion, in this research too, others aims purpose to study roles of acanthus harvesting on the different gradients and orientations on erosion acceleration. In this reason, these plots established on the four different slopes and two different aspects. The amount of sediment has been measured from plots in 9 time precipitation when it falls on late winter and early spring in 2007. Factor analyze and two ways ANOVA were the techniques that used for data analyzing.

Diverse factors affect the characteristics of the watershed that lead to spatial and temporal variations in the runoff and sediment production processes. Runoff and sediment are the main important elements in the hydrological cycle, and their changes directly affect river systems and sedimentary environments; and their spatial and temporal variations change the morphology of the rivers. Due to differences in soil characteristics, source materials and geological formations, vegetation and slope in different parts of a region, the amount of runoff and sediment produced in these areas can vary with spatial variations. The purpose of this study is to evaluate the spatial variations of runoff and sediment and runoff threshold using rainfall simulation data in the Gharehshiran watershed in Ardebil Province. Considering the importance of spatial distribution of sampling points across the catchment area, the locations of the samples were determined, taking into account the access path to the points, as well as sampling in different formations through determining the boundaries of the study area. The field experiments and simulation of precipitation were carried out using a 1×1m rainfall simulator in 45 points in different geologic formations of the watershed area. The amount of runoff and sediment were measured in each experiment along with recording the threshold time of runoff generation. The measured variables were mapped and interpolated by using Kriging method over the study area. To assess the accuracy of the interpolation results, 7 samples were selected randomly and the Root Mean Square Error (RMSE), Mean Absolute Error (MAE) and Mean Bias Error (MBE) statistical measures were calculated by comparing observational and estimated values. Then, the correlation between the studied variables in various geological formations was evaluated using Pearson correlation analysis. The relationship between sediment and runoff amount, and runoff threshold time were also evaluated using a triple diagram model. The results of the interpolated maps showed that the lowest values of runoff time threshold (1. 99-3. 17 min) were observed in the geological formations of upper part of the watershed having dacite and tracite igneous, volcanic rocks. While the runoff time thresholds were increased (6. 13-7. 25 min) in the low land areas with the old alluvial terraces. The amount of generated runoff in the upper hillslopes of the watershed with dacite and tracite rocks was estimated as (6. 07-7. 25 lit/m2), and the amount of sediment was low (1. 25-1. 66 g/l). Meanwhile, in the lower parts of old alluvial terraces, the amount of runoff production was low (2. 20-3. 50 lit/m2) and the amount of produced sediment was higher with values of (2. 25-3. 5 g/l). The results of correlation analysis showed that the correlation coefficients between runoff threshold and runoff volume were significant at 0. 01 significant level (r =-0. 802). Also, a significant negative correlation (r =-0. 672), were observed between runoff and sediment values. The relationship between the runoff time threshold and the sediment content was positive at significant level of 0. 01 (r = 0. 900). The results of interdependency between the sediment, runoff and runoff time threshold values using triple diagram models showed that the sediment amount was about 2g/l at high runoff time thresholds of 4 minutes with 2. 5-5. 5 lit/m2 runoff amounts. In general, it can be said that the sediment production in the study area is strongly under the effects of runoff amounts in lower time thresholds of runoff. As a remark, the results pointed out that the internal relationship of runoff and sediment production are affected by a variety of effective factors which requires comprehensive studies to reach a final conclusion.

Accelerated soil erosion is the most important degradation factor of soil and water resources. Typically, soil erosion involves the detachment and transport of soil particles by rainfall, shallow surface flow or the interaction of these two factors. Therefore, understanding the motion threshold of sediment particles and temporal variation of sediment concentration in flow-induced can provide a detailed cognition of the processes inducing soil erosion and sediment transport and their eventual interactions. It is also important for increasing the accuracy of soil erosion models. In this study, the particle motion threshold and temporal variation of sediment were studied for a sandy sample at three slopes; 3. 1, 5. 9, 8. 9% and-dunder three flow discharges of 4. 78, 7. 12 and 9. 05 (×10-5 m2 s-1). This study was carried out in the laboratory conditions using a flume with 240 cm long by 40 cm width. The results showed that the Shields curve is not suitable for this study to determine the motion threshold. The threshold stream power of particle motion was determined 0. 035 W m-2. Also, with increasing slope and consequently increasing stream power up to 0. 05 W m-2, the erosion intensity increased and soil erosion changed from sheet erosion to rill erosion. The results indicate that the formation and development of rill erosion would be the main factor for soil loss and sediment production in hillslopes. Therefore, prevention of rill formation by strip croping, terracing and terrace farming is an effective strategy for soil conservation.

Introduction: Cochlear dead zones are defined as areas where the inner hair cells have been destroyed.Thresholds on the audiograms show the integrity of those parts of the ear that are tested. Care must be taken in interpretating audiograms. Thanks to the advances in understanding of cochlear functions, it is now possible to spot false responses that come from dead zones of the cochlea. Recently, cochlear dead regions have been detected via TEN (Threshold Equalizing Noise) test in which ipsilateral broadband noise and threshold shifting are used.Materials and Methods: A review of the literature on the subject of dead zones published from 1993 to 2003 was performed using Pubmed, Ebsco, Science Direct, Google Scholar Thieme ProQuest databases and library sources. key word: were "cochlear dead zone", "traveling wave", "ten (threshold equalizing noise) test", "ipsilateral noise" and "real-ear measurement for hearing aids prescription".Conclusion: Hearing aids fitting process for patients with severe and sloping sensory neural hearing loss must be noted specially by amplifying active zone and avoiding amplification for dead region i.e., offering amplification to the transition frequencies that have better hearing than others, those among the fine regions and the dead zones. Dead zone detection may help in hearing aids fitting and fine tuning.

Gully erosion has an important role in Fars province due to sediment production and enormous damages to land, roads and infrastructures. In this research, 15 gullies were selected to measure their morphometric characteristics. The length, depth, top and bottom width and volume of gully erosion were then measured. Influential factors on the sediment production and gully development were analyzed and determined by using stepwise method in SPSS software. The results indicate that sediment production due to gully development is related to three variables including drainage area, silt and the sand percent of the watershed above the gully heads. These results imply that surface runoff is acting as dominant hydrologic process on gully development. Investigation on the topographic threshold reveals that drainage area exponent (b) is negative and these results are in the same line with the results of some recent relevant studies. The results also indicate the watershed characteristics and geological formation impact on the gully sediment production. Gully development could be reduced by decreasing the area of bare land as the main source of surface runoff by vegetation planting and terracing. Constructing of small earth dams at the end of gullies collect surface runoff and provides better situations for vegetation establishment around gullies.

Purpose: To compare the sensitivity, specificity and validity of SITAfast (SiF) strategy with the standard full thershold (SFT) algorithm in the Humphrey field analyzer. Materials &Methods: As an observational case series, twenty glaucoma patients (37 eyes) who were referred to Emam Reza & Ghaem eye clinic, central field testing was performed with the central 30-2 program using SFT and SiF strategies. Both tests were carried out on four different days in a span of two weeks. Sensitivity, specificity, validity, time saved, and the extent of defect in SITA fast strategies were compared with those of SFT. Results: The sensitivity of SFT & SiF was 93.3%. Specificity of SFT & SiF was 71.4% & 57.4% respectively. The validity of SFT & SiF was 89.2% & 86.5% respectively. The mean time in SFT, SiF were 14.6 min & 5.45 min, respectively. Defects in gray scale was shallower in SiF (significant at P<1%, P<0.5%) but defects in the pattern deviation plots tended to be more in SITA fast strategy but there was no significant difference in statistics. Conclusion: SITA fast strategy has good sensitivity and is significantly faster as compared with the SFT algorithm. Test time is much shorter so common use of SiF is suggested. In children, old age patients and patients who has difficulty in concentration, SiF is superior to SFT.          

ABSTRACT Today, climate change and its obvious negative effects on ecosystems have caused concern. This research seeks to test whether vegetation changes are sensitive to climate shocks and also how the ecosystem recovery process is through this index. In this regard, by using the GEE platform, Java coding, GIS and statistical analysis, vegetation and Palmer indices were calculated and based on time series climate data, vegetation and climate changes were presented. The results of Palmer's drought index show that during the statistical period (1985-2020) the study area is facing drought or is moving towards drought. Also, the results indicate the longest period of drought in the region from 2013 to 2020. Totaly from 420 evaluated months, the NDVI index is below the change threshold in 70 months. Among these, 31 months of the study period is below the acceptable threshold in green and non-reservoir seasons, which is ecologically worrying. The distribution of the vegetation index based on hexagons in 1985 and 2005 had a normal and almost normal distribution; But in 2020, the graph deviated from the normal state and skewed towards the vegetation cover index under stress or even thin covers. According to the analysis of the indicators, it is predicted that the Gorgan region is on the border of such ecological developments and the historical ecosystem of the region is moving towards new ecosystems or being in a new equilibrium state with climatic conditions and human disturbances Extended Abstract Introduction Today, climate change and its obvious negative effects on terrestrial ecosystems have caused great concern to humans. These changes are effective on vegetation performance, plant distribution patterns, and have economic and environmental consequences. Therefore, it is important to know the behavioral pattern of vegetation changes against climate changes. Reviewing the studies of scientists in the world shows many researchers have used the NDVI index to study temporal and spatial changes in vegetation and its relationship with the climatic index of precipitation in different parts of the world. Studies have shown that NDVI follows precipitation with different time scales. Surveys showed that there are very few studies on determining the threshold of changes in the vegetation cover index in the face of climate shocks. Determining these thresholds can provide a suitable solution for evaluating the state of the ecosystem, the consequences of climate shocks and the reversibility or disturbance in the ecosystem. This study was conducted with the aim of improving our understanding of the dynamics of vegetation in the forest city of Gorgan during 1985-2020 against climatic stresses.   Methodology The current research is a comparative and monitoring research and seeks to test whether changes in vegetation cover are sensitive to climate shocks and also how the ecosystem recovery process is through this index. To achieve the gole, first, NDVI index was selected among the optimal vegetation indices and its calculation process was done as a time series in the GEE system. In parallel with those climate shocks, the main elements including temperature, precipitation and storm were calculated during the historical process of 35 years and the average and standard deviation statistical indicators were calculated for them and the trend of changes in the thresholds was determined. The results of climate plots and climate changes show that in the years before 1985, 2005 and 2020, drastic changes have occurred in climatic elements and climatic factors. Therefore, these years can be considered as the periods when the climate shock happened.. Next, the region was divided into 436 hexagons and the NDVI index for each of the hexagons was calculated and modeled for the years 1985, 2005 and 2020 as selected years affected by climate shocks. In conclusion, to analyze the trend of changes in the time series of the vegetation index and compare the behavior of its changes with climatic indices, the Palmer index was calculated.   Results and discussion The results of climate change monitoring based on the Palmer index showed that during the statistical period the study area is facing drought in most years. The most severe climatic fluctuations and drought in the region were recorded in 2018 and in the months of October to December. The longest period of drought has also prevailed in the region from 2013 to 2020. During this period, rainfall, temperature and storm fluctuations have the most changes. The results of drought monitoring show that in 270 months, the region is facing climatic drought stress, 57 months of the study period, the region is facing severe and very severe drought stress. The results of the time series of the NDVI vegetation index showed that, out of the 420 evaluated months, 70 months of the year the NDVI index is below the change threshold, 31 of which are in the green and non-accumulating seasons, the seasons when the vegetation is expected to be at its maximum. Placing below the acceptable range means crossing the ecological thresholds and challenges the recovery and restoration of the ecosystem, also the ecological performance will be affected at this point. Based on the assessment of the Palmer index, from 2014 to 2019, the situation of the Palmer index is in the extreme drought range. Also, since 2015, i.e. with a one-year time delay, NDVI index has experienced the lower limit of the equilibrium threshold of vegetation cover. These conditions are also valid for the years 2008, 2009, 2002 and 1997. In general, it can be said that the vegetation cover index is dependent on climatic changes and fluctuations and shows high sensitivity to changes. The important point in this section is that in the years when the NDVI index changes are at the lower limit of the threshold, we witness the most climate shocks and temperature changes, the occurrence of severe storms and precipitation fluctuations. The distribution of the vegetation index based on hexagons in 1985 and 2005 have a normal distribution; but in 2020, the graph has deviated from the normal state and skewed towards the vegetation cover index under stress or even thin covers. The visual interpretation done on the vegetation cover index in 1985 confirms the condition of the vegetation cover in the southern and western limits of the region in a state with suitable dense and pasture vegetation and forest cover on the edges. However, in 2005 and 2020, this cover has been changed and mainly turned into agricultural land and poor rangeland. In such a way that in 2020, the situation of the region has revealed the critical state of vegetation. The vegetation cover index in the central areas of the city has also reached from a relatively favorable situation in 1985 to a critical situation with almost no dense and stress-free vegetation cover in 2020. The results of the present studies are consistent with the studies of Visentr Serrano et al. in 2013 and confirm the relationship between NDVI vegetation and climate change. In addition, the results of the studies are consistent with the studies of Alwesabi 2012, Xiai & Moody, 2005 and Yan et al. 2001. In such a way that the present study and the aforementioned studies all confirm the influence of the vegetation index on climate fluctuations and precipitation with a one-year time difference.       Conclusion In general, the threshold is defined as a border with different conditions. After crossing the thresholds, the stability and positioning of the NDVI in the equilibrium range is often difficult, and the ecosystem is constantly spending energy to restore itself or to position itself in a new stability state. The result of the mentioned disorders is the reduction of resilience and resistance in the region, which leads the ecosystem to alternative states or crossing the threshold or being in a new equilibrium state. The results showed that the areas where green vegetation is concentrated and denser are less affected by climatic stresses and show more resilience. However, the areas that have become spots and islands due to destruction in the urban areas are more affected by climatic stress and destruction and show less tolerance against the destruction factors. The results help managers to focus their management plans for the preservation and maintenance of urban green spaces as well as forest and pasture ecotones on the edge of the city by knowing the thresholds.   Funding There is no funding support.   Authors’ Contribution Authors contributed equally to the conceptualization and writing of the article. All of the authors approved thecontent of the manuscript and agreed on all aspects of the work declaration of competing interest none.   Conflict of Interest Authors declared no conflict of interest.   Acknowledgments  We are grateful to all the scientific consultants of this paper.