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Search Results: 1 - 10 of 563398 matches for " E. A. Baltas "
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Impact on Water Resources in a Mountainous Basin under the Climate Change Transient Scenario (UKTR)  [PDF]
E. A. Baltas
American Journal of Climate Change (AJCC) , 2014, DOI: 10.4236/ajcc.2014.31010

The impact of climate change on the hydrological regime and water resources in the basin of Venetikos river, in Greece is assessed. A monthly conceptual water balance model was calibrated in this basin using historical hydro meteorological data. This calibrated model was used to estimate runoff under a transient scenario (UKTR) referring to year 2080. The results show that the mean annual runoff, mean winter and summer runoff values, annual maximum and minimum values, as well as, monthly maximum and minimum, will be reduced. Additionally, an increase of potential and actual evapotranspiration was noticed due to temperature increase.

Technical Note: Determination of the SCS initial abstraction ratio in an experimental watershed in Greece
E. A. Baltas, N. A. Dervos,M. A. Mimikou
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2007,
Abstract: The present study was conducted in an experimental watershed in Attica, Greece, using observed rainfall/runoff events. The objective of the study was the determination of the initial abstraction ratio of the watershed. The average ratio (Ia/S) of the entire watershed was equal to 0.014. The corresponding ratio at a subwatershed was 0.037. The difference was attributed to the different spatial distribution of landuses and geological formations at the extent of the watershed. Both of the determined ratios are close to the ratio value of 0.05 that has been suggested from many studies for the improvement of the SCS-CN method.
Research on the initial abstraction – storage ratio and its effect on hydrograph simulation at a watershed in Greece
E. A. Baltas,N. A. Dervos,M. A. Mimikou
Hydrology and Earth System Sciences Discussions , 2007,
Abstract: The present research was conducted at an experimental watershed in the prefecture of Attica, Greece, using the selected observed rainfall-runoff events from a four-year time period. The objectives of this study were two: The first was the determination of the initial abstraction Ia – watershed storage S ratio. The average ratio (Ia/S) was equal to 0.014. The corresponding ratio at a subwatershed was 0.037. The difference was attributed to the different spatial distribution of landuses at the extent of the watershed. The second objective of the study was to examine the effect of the SCS empirical equation on hydrograph simulation. This was investigated through the comparison between the observed and two different simulated hydrographs at each one out of eighteen selected storm events. The simulated hydrographs were calculated by applying on the watershed's unit hydrograph two time distributions of excess rainfall that derived from the SCS method using two different approaches. In the first approach, the initial abstraction was determined from the observed rainfall-runoff data, while in the second, it was calculated using the SCS empirical equation. It was found that the SCS empirical equation estimates greater amount of initial abstraction and leads to the delayed start of the excess rainfall and the simulated runoff. This resulted in the overestimation of the peak flow rate and the time to peak at the majority of the storm events.
Statistical and neural classifiers in estimating rain rate from weather radar measurements
E. Baltas
Advances in Geosciences (ADGEO) , 2007,
Abstract: A distributed rainfall-runoff model capable for real time flood forecasting utilizing highly spatial and time resolution data was developed. The study region is located under the WSR-74 S-band 100 km radar umbrella and is equipped with a number of rain gauge recording stations, a permanent installation for flow measurement and a stage recorder. The entire basin was digitized to 2×2 km2 grid squares by implying GIS techniques. A series of rainfall events recorded producing floods were analyzed and processed. The linear channel parameter assigned to each grid-square is based on its location measured by the centroid of the grid square along the channel network. The estimation of the hill-slope and the stream velocity are calculated based on the Geographic Information System (GIS) procedures.
Assessment of Climate Change Impacts in Greece: A General Overview  [PDF]
Maria A. Mimikou, Evangelos A. Baltas
American Journal of Climate Change (AJCC) , 2013, DOI: 10.4236/ajcc.2013.21005

The climatic and hydrological systems are tightly related and any induced changes cause chained interactions. In an attempt to adequately manage water resources in Greece, a series of experiments were conducted with different GCMs in selected study areas to understand this interplay. This paper is an overview of the studies carried out in the Aliakmon, the Upper Acheloos, the Portaikos, and the Pinios basins, where the regional hydrological cycle was evaluated on river basin spatial scale to assess regional impacts and variability. The impacts of climate change on the water resources are presented in a synthetic quantitative way, in order to draw general conclusions concerning the trends of the hydrological indicators. A good agreement was observed between the different climatic experiments, and the trends on the selected hydrological indicators demonstrate an increase in temperature and PET, reduction in the mean annual precipitation and runoff, and a shifting of the snowmelt period towards the winter, while the snowpack storage was proved to be a controlling factor. It is accentuated that relatively small decreases in the mean annual precipitation cause dramatic increase of reservoir risk levels of annual firm water supply and energy production. As a result, radical increases of reservoir storage volume are required to maintain firm water and energy yields at tolerable risk levels. The adaptive capacity of the country is not that high, and a series of serious actions need to be taken in order to mitigate the effects of climate change and assess its impacts.

Hydroxyl-platelet-activating factor exists in blood of healthy volunteers and periodontal patients
Smaragdi Antonopoulou,Alexandros Tsoupras,George Baltas,Helen Kotsifaki,Zacharias Mantzavinos,Constantinos A. Demopoulos
Mediators of Inflammation , 2003, DOI: 10.1080/09629350310001599666
Abstract: Periodontal diseases are localized chronic inflammatory conditions of the gingival and underlying bone and connective tissue. Platelet-activating factor (PAF), a potent inflammatory phospholipid mediator that has been previously detected in elevated levels in inflamed gingival tissues, in gingival crevicular fluid and in saliva, is implicated in periodontal disease. Our results from previous studies showed that the biologically active phospholipid detected in gingival crevicular fluid is a hydroxyl-PAF analogue. In this study, hydroxyl-PAF analogue was detected for the first time in human blood derived from patients with chronic periodontitis as well as from periodontally healthy volunteers. The hydroxyl-PAF analogue was purified by high-performance liquid chromatography, detected by biological assays and identified by electrospray analysis. In addition, the quantitative determination of PAF and hydroxyl-PAF analogue (expressed as PAF-like activity) showed a statistically significant increase in the ratio of hydroxyl-PAF analogue levels to PAF levels in periodontal patients, suggesting that this bioactive lipid may play a role in oral inflammation.
Animal-Assisted Therapy for Improving Human Health
Sibel Cevizci,Ethem Erginoz,Zuhal Baltas
TAF Preventive Medicine Bulletin , 2009,
Abstract: Animal Assisted Therapy (AAT) or Pet Therapy is an adjunctive therapy by taking advantage of human and animal interaction, activate the physiological and psychological mechanisms, initiate positive changes improving health in metabolism. In recent years, this interaction are in use to treat psychological and psychiatric disorders such as stress, depression, loneliness, pervasive developmental disorders affect negatively to human health. Furthermore, AAT has been increasingly used to improve quality of life, hypertension, cardiovascular diseases, chronic illnesses such as cancer and AIDS. The aim of this paper is to identify AAT by reviewing human and animal interaction, evaluate how AAT has a scientific background from past to now. Also, we aim to give some information about the risks, institutional applications, some factors referring AAT s mechanism of action and chronic diseases, psychological and physical improvements provided with animal assisted therapies. The therapy results will be evaluated more advisable providing AAT is being applied with public health specialist, veterinarian, physician, psychologist, psychiatrist and veterinary public health experts who are monitor applications. Especially, the psychosomatic effects result from physical, emotional and play mechanism of action of HDT can be used for improving quality of life in individuals with chronic diseases. In Turkey, there is no any investigation which have been performed in this scientific field. It is quitely important to evaluate the benefits of this therapy accurately and to select various methods proper to diseases. Consequently, it is obvious that AAT will be considered by the healthcare services as a supportive therapy process for improving human health in Turkey and needs further studies. [TAF Prev Med Bull. 2009; 8(3): 263-272]
A detailed dosimetric comparison between manual and inverse plans in HDR intracavitary/interstitial cervical cancer brachytherapy
Petra Trnková,Dimos Baltas,Andreas Karabis,Markus Stock
Journal of Contemporary Brachytherapy , 2010,
Abstract: Purpose: The purpose of this study was to compare two inverse planning algorithms for cervical cancer brachytherapy and a conventional manual treatment planning according to the MUW (Medical University of Vienna) protocol.Material and methods: For 20 patients, manually optimized, and, inversely optimized treatment plans with Hybrid Inverse treatment Planning and Optimization (HIPO) and with Inverse Planning Simulated Annealing (IPSA) were created. Dosimetric parameters, absolute volumes of normal tissue receiving reference doses, absolute loading times of tandem, ring and interstitial needles, Paddick and COIN conformity indices were evaluated.Results: HIPO was able to achieve a similar dose distribution to manual planning with the restriction of high dose regions. It reduced the loading time of needles and the overall treatment time. The values of both conformity indices were the lowest. IPSA was able to achieve acceptable dosimetric results. However, it overloaded the needles.This resulted in high dose regions located in the normal tissue. The Paddick index for the volume of two times prescribed dose was outstandingly low.Conclusions: HIPO can produce clinically acceptable treatment plans with the elimination of high dose regions in normal tissue. Compared to IPSA, it is an inverse optimization method which takes into account current clinical experience gained from manual treatment planning.
Radiobiologically based treatment plan evaluation for prostate seed implants
Courtney Knaup,Panayiotis Mavroidis,Carlos Esquivel,Dimos Baltas
Journal of Contemporary Brachytherapy , 2011,
Abstract: Purpose: Accurate prostate low dose-rate brachytherapy treatment plan evaluation is important for future care decisions. Presently, an evaluation is based on dosimetric quantifiers for the tumor and organs at risk. However, these do not account for effects of varying dose-rate, tumor repopulation and other biological effects. In this work, incorporation of the biological response is used to obtain more clinically relevant treatment plan evaluation.Material and methods: Eleven patients were evaluated. Each patient received a 145 Gy implant. Iodine-125 seeds were used and the treatment plans were created on the Prowess system. Based on CT images the post-implant plan was created. In the post-plan, the tumor, urethra, bladder and rectum were contoured. The biologically effective dose was used to determine the tumor control probability and the normal tissue complication probabilities for the urethra, bladder, rectum and surrounding tissue. Results: The average tumor control probability and complication probabilities for the urethra, bladder, rectum and surrounding tissue were 99%, 29%, 0%, 12% and 6%, respectively. These measures provide a simpler means for evaluation and since they include radiobiological factors, they provide more reliable estimation of the treatment outcome. Conclusions: The goal of this work was to create more clinically relevant prostate seed-implant evaluation by incorporating radiobiological measures. This resulted in a simpler descriptor of treatment plan quality and was consistent with patient outcomes.
BiopSee – transperineal stereotactic navigated prostate biopsy
Pawel Zogal,Georgios Sakas,Woerner R?sch,Dimos Baltas
Journal of Contemporary Brachytherapy , 2011,
Abstract: In the recent years, prostate cancer was the most commonly diagnosed cancer in men. Currently secure diagnosis confirmation is done by a transrectal biopsy and following histopathological examination. Conventional transrectal biopsy success rates are rather low with ca. 30% detection upon the first and ca 20% after re-biopsy. The paper presents a novel system for stereotactic navigated prostate biopsy. The approach results into higher accuracy, reproducibility and unrestricted and effective access to all prostate regions. Custom designed ultrasound, new template design and integrated 2-axes stepper allows superior 2D and 3D prostate imaging quality and precise needle navigation. DICOM functionality and image fusion enable to import pre-operative datasets (e.g. multiparametric MRI, targets etc.) and overlay all available radiological information into the biopsy planning and guiding procedure. The biopsy needle insertion itself is performed under augmented reality ultrasound guidance. Each procedure step is automatically documented in order to provide quality assurance and permit data re-usage for the further treatment. First clinical results indicates success rates of ca. 70% by first biopsies by our approach.
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