OALib Journal期刊

ISSN: 2333-9721



匹配条件: “Hamidreza Pourreza” ,找到相关结果约483条。
Localization of Hard Exudates in Retinal Fundus Image by Mathematical Morphology Operations
Mehdi Ghafourian Fakhar Eadgahi,Hamidreza Pourreza
Journal of Theoretical Physics and Cryptography , 2012,
Abstract: Diabetic retinopathy is one of the leading causes of blindness in the world. Detection of hard exudates is an important step for early diagnosis in eye diseases such as Macular Edema(ME). If hard exudates were segmented precisely, laser treatments can be applied more effective for patients by surgeons. The possibility of blindness is very high when the hard exudates are very close to Macula region or Optic disc. Therefore, fast and accurate segmentation is one of the most important factors in elimination of hard exudates. In this paper, a method is proposed for segmentation of hard exudates in retinal color image based on morphological operation. In the proposed method, the retinal images preprocessed and optic disc and the blood vessels identified primarily and then they eliminate from the image. Finally, the Hard Exudates (HEs) are segmented by mixture of morphological operation such as Top-hat, Bottom-hat and reconstruction operations. The proposed method was tested on DIARETDB1 database and 78.28% of sensitivity was obtained. Comparing to other recent automatic method available in the literature, our proposed method can obtain acceptable exudates detection result in term of sensitivity.
Focal neuropathies following percutaneous nephrolithotomy (PCNL) – preliminary study [Fokale Neuropathien nach perkutaner Nephrolithotomie (PCNL)]
Nasseh, Hamidreza,Pourreza, Farshid,Saberi, Alia,Kazemnejad, Ehsan
GMS German Medical Science , 2013, DOI: 10.3205/000175
Abstract: [english] Introduction: Postoperative neurological complications in pelvic and renal surgery are a well-known clinical problem and their morbidities are important. We designed this study to determine prevalence and risk factors of such complications after percutaneous nephrolithotomy (PCNL) surgery.Material and methods: A cross-sectional study was performed during February and July 2011 on 68 PCNL cases. Demographic data and surgery reports were gathered and comprehensive neurological physical examination carried out before and after surgery. Then, data was analyzed using software SPSS 18. Results: The ultimate sample included 30 (46.2%) male and 35 (53.8%) female patients with a mean age of 47.9 ± 11.47 years. In intercostal and lumbosacral plexus area, sensory neurological complications occurred in 8 patients (12.31%), 4 men and 4 women. The most common involved dermatomes and nerves were T12 (8 cases). There was a significant correlation between prolonged duration of surgery and prevalence of sensory complications (p<0.010). The highest hemoglobin value drop after surgery occurred in patients with neurological complications (p<0.001). There were no correlations between age, tracts used, diabetes mellitus, BMI, hypertension, positioning of patients and side of surgery with incidence of sensory neurological complications. No motor neurological complications occurred. Conclusion: Prolonged duration of PCNL and increased value of hemoglobin drop may lead to increased risk of neuropathy. Larger prospective studies with retroperitoneal imagings and patients’ follow up is suggested for better understanding of this complication. [german] Einleitung: Postoperative neurologische Komplikationen bei operativem Eingriff an Becken und Niere sind ein bekanntes klinisches Problem und deren Krankheitsverl ufe sind wichtig. Wir planten diese Studie, um die Pr valenz und die Risikofaktoren derartiger Komplikationen nach perkutaner Nephrolithotomie (PCNL) zu erfassen.Material und Methoden: Von Februar bis Juli 2011 wurde eine Querschnittstudie an 68 PCNL-F llen durchgeführt. Die demographischen Daten und die Operationsberichte wurden ausgewertet und umfassende neurologische und k rperliche Untersuchungen wurden vor und nach dem chirurgischen Eingriff vorgenommen. Die Daten wurden mit der Software SPSS 18 analysiert.Ergebnisse: In die Studie einbezogen wurden 30 m nnliche (46,2%) und 35 (53,8%) weibliche Patienten mit einem mittleren Alter von 47,9 ± 11,47 Jahren. Bei 8 Patienten (12,31%), bei 4 M nnern und 4 Frauen, wurden im Bereich des interkostalen und lumbosakralen P
Towards the Application of Linear Programming Methods For Multi-Camera Pose Estimation
Masoud Aghamohamadian-Sharbaf,Ahmadreza Heravi,Hamidreza Pourreza
Computer Science , 2015,
Abstract: We presented a separation based optimization algorithm which, rather than optimization the entire variables altogether, This would allow us to employ: 1) a class of nonlinear functions with three variables and 2) a convex quadratic multivariable polynomial, for minimization of reprojection error. Neglecting the inversion required to minimize the nonlinear functions, in this paper we demonstrate how separation allows eradication of matrix inversion.
Fabrication and Studying the Mechanical Properties of A356 Alloy Reinforced with Al2O3-10% Vol. ZrO2 Nano-particles through Stir Casting  [PDF]
Mohsen Hajizamani, Hamidreza Baharvandi
Advances in Materials Physics and Chemistry (AMPC) , 2011, DOI: 10.4236/ampc.2011.12005
Abstract: Al2O3-ZrO2 with a high level of hardness and toughness is known as ceramic steel. Due to its unique properties it can be used as a reinforcement in fabrication of metal matrix composites. In this study, nanoparticles of Al2O3-10% ZrO2 with an average size of 80 nm were used to fabricate Al matrix composites containing 0.5, 1, 1.5 and 2 wt.% of the reinforcement. The fabrication route was stir casting at 850?C. There is no report about usage of this reinforcement in fabrication of composites in the literature. The microstructures of the as-cast composites were studied by scanning electron microscope (SEM). Density measurement, hardness and tensile properties were carried out to identify the mechanical properties of the composites. The results revealed that with increasing the reinforcement content, density decreased while yield, ultimate tensile strength and compressive strength increased. Also, hardness increased by increasing the reinforcement content up to 1 wt.% Al2O3-10% ZrO2 but it decreased in the samples containing higher amounts of reinforcement.
Training Based Channel Estimation in MIMO-OFDM Systems  [PDF]
Maryam Imani, Hamidreza Bakhshi
Communications and Network (CN) , 2012, DOI: 10.4236/cn.2012.41008
Abstract: OFDM combined with the MIMO technique has become a core and attractive technology in future wireless communication systems and can be used to both improve capacity and quality of mobile wireless systems. Accurate and efficient channel estimation plays a key role in MIMO-OFDM communication systems, which is typically realized by using pilot or training sequences by virtue of low complexity and considerable performance. In this paper, we discuss some methods for channel estimation based training symbols in MIMO-OFDM systems. The results confirm the superiority of the represented methods over the existing ones in terms of bandwidth efficiency and estimation error.
The Tight Bound for the Number of Pilots in Channel Estimation for OFDM Systems  [PDF]
Maryam Imani, Hamidreza Bakhshi
Communications and Network (CN) , 2012, DOI: 10.4236/cn.2012.42019
Abstract: Coherent detection in OFDM systems requires accurate channel state information (CSI) at the receiver. Channel estimation based on pilot-symbol-assisted transmissions provides a reliable way to obtain CSI. Use of pilot symbols for channel estimation, introduces overhead and it is desirable to keep the number of pilot symbols as minimum as possible. This paper introduces a new tight bound for the number of pilots in channel estimation using adaptive scheme in OFDM systems. We calculate the minimum number of necessary pilots using two approaches. The first approach for the number of pilots is obtained based on Doppler frequency shift estimation and the second approach is acquired based on channel length estimation using second order statistics of received signal. Finally we obtain the tight bound for the number of pilots using attained values.
Offline Signature Verification Using Local Radon Transform and Support Vector Machines
Vahid Kiani,Reza Pourreza,Hamid Reza Pourreza
International Journal of Image Processing , 2009,
Abstract: In this paper, we propose a new method for signature verification using local Radon Transform. The proposed method uses Radon Transform locally as feature extractor and Support Vector Machine (SVM) as classifier. The main idea of our method is using Radon Transform locally for line segments detection and feature extraction, against using it globally. The advantages of the proposed method are robustness to noise, size invariance and shift invariance. Having used a dataset of 600 signatures from 20 Persian writers, and another dataset of 924 signatures from 22 English writers, our system achieves good results. The experimental results of our method are compared with two other methods. This comparison shows that our method has good performance for signature identification and verification in different cultures.
Psychology Consequences of Abortion Among The Post Abortion Care Seeking Women in Tehran
Abolghasem Pourreza,Aziz Batebi
Iranian Journal of Psychiatry , 2011,
Abstract: "nObjective: abortion either medical or criminal has distinctive physical, social, and psychological side effects. Detecting types and frequent psychological side effects of abortion among post abortion care seeking women in Tehran was the main objective of the present study. "n Method: 278 women of reproductive age (15-49) interviewed as study population. Response rate was 93/8. Data collected through a questionnaire with 2 parts meeting broad socio-economic characteristics of the respondents and health- related abortion consequences. Tehran hospitals were the site of study. "nResults: The results revealed that at least one-third of the respondents have experienced psychological side effects. Depression, worrying about not being able to conceive again and abnormal eating behaviors were reported as dominant psychological consequences of abortion among the respondents. Decreased self-esteem, nightmare, guilt, and regret with 43.7%, 39.5%, 37.5%, and 33.3% prevalence rates have been placed in the lower status, respectively. "nConclusion: Psychological consequences of abortion have considerably been neglected. Several barriers made findings limited. Different types of psychological side effects, however, experienced by the study population require more intensive attention because of chronic characteristic of psychological disorders, and women's health impact on family and population health.
Serum Proteins and Some Biochemical Parameters in Broiler Chickens Fed with Raw and Treated Bitter Vetch (Vicia ervilia) Seeds
Gh. Sadeghi,J. Pourreza
Pakistan Journal of Biological Sciences , 2007,
Abstract: This study carried out to evaluate the effect of bitter vetch seeds on serum proteins and biochemical parameters in broiler chickens. A total of 1320 one-day old broiler chicks of a commercial breed were placed in 64 pens. Treatments were included raw and four different processed bitter vetch seeds in three levels (150, 300 and 450 g kg-1) and a corn-soybean based diet as control. Each treatment group consisted of four replicates. Processing methods were included soaked in water for 12 h, autoclaved, then dried at room temperature (SAD); ground, soaked in water for 24 h, autoclaved and dried (GSAD); ground, soaked in water for 47 h with exchange water every 12 h, cooked and dried (GSCD) and ground, soaked at 1% acetic acid solution for 24 h at 60°C (AA). Feeding raw, AA and GSAD seeds decreased serum albumin significantly (p<0.05) in 21 days old chicks. Chickens that fed with raw and treated bitter vetch seed had lower α1 and γ globulins than control (p<0.05). Increasing raw and treated bitter vetch seeds from 15 to 30 and 45% decreased albumin, α1 and γ globulins and increased α2 and β globulins significantly (p<0.05). In 14 days old chicks feeding raw and treated biter vetch had no effect on serum urea, but uric acid concentration decreased significantly (p<0.05). Feeding SAD seeds increased serum urea significantly (p<0.05), but uric acid concentration did not change with feeding raw and treated bitter vetch seeds in 42 day old chicks. Adding raw and treated bitter vetch seeds to diet increased T4 and decreased T3 concentrations in all ages. At 28 days old chicks, feeding raw and treated biter vetch seeds decreased alkaline phosphatase concentration significantly than control. Results showed that raw bitter vetch seeds have some toxic effects on metabolism in broiler chickens and GSCD and SAD treatments were more effective to detoxification of this seed.
The Moderating Role of Power Distance on the Relationship between Employee Participation and Outcome Variables
Sima Rafiei,Abolghasem Pourreza
International Journal of Health Policy and Management , 2013,
Abstract: Background Many organisations have realised the importance of human resource for their competitive advantage. Empowering employees is therefore essential for organisational effectiveness. This study aimed to investigate the relationship between employee participation with outcome variables such as organisational commitment, job satisfaction, perception of justice in an organisation and readiness to accept job responsibilities. It further examined the impact of power distance on the relationship between participation and four outcome variables. Methods This was a cross sectional study with a descriptive research design conducted among employees and managers of hospitals affiliated with Tehran University of Medical Sciences, Tehran, Iran. A questionnaire as a main procedure to gather data was developed, distributed and collected. Descriptive statistics, Pearson correlation coefficient and moderated multiple regression were used to analyse the study data. Results Findings of the study showed that the level of power distance perceived by employees had a significant relationship with employee participation, organisational commitment, job satisfaction, perception of justice and readiness to accept job responsibilities. There was also a significant relationship between employee participation and four outcome variables. The moderated multiple regression results supported the hypothesis that power distance had a significant effect on the relationship between employee participation and four outcome variables. Conclusion Organisations in which employee empowerment is practiced through diverse means such as participating them in decision making related to their field of work, appear to have more committed and satisfied employees with positive perception toward justice in the organisational interactions and readiness to accept job responsibilities.

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