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Search Results: 1 - 10 of 11311 matches for " George Peppas "
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The Efficiency in Liquidity Measures during the US Monetary Announcements  [PDF]
Dimitrios I. Vortelinos, Konstantinos Gkillas, Christoforos Konstantatos, George Peppas
Theoretical Economics Letters (TEL) , 2018, DOI: 10.4236/tel.2018.81006
Abstract: We examine the impact of US economic news releases in the liquidity of eleven not so extensively researched emerging stock markets. We employ ten liquidity measures. The sample begins from June 2007 up to December 2016. Analysis is performed in a weekly frequency. China is the least liquid Asian market. Peru is the most liquid Latin American market. Most of the emerging markets are positively affected by the US news, offering diversification benefits to international investors. India and Argentina (China and Chile) are the Asian and Latin American countries with the highest (lowest) impacts, respectively. There is not a single best-in-class liquidity measure. The country with the lowest liquidity has the lowest impact from the US news releases. This result holds for both groups of countries in Asia and Latin America.
An analysis of patient house calls in the area of Attica, Greece
George Peppas, George Theocharis, Efthymia A Karveli, Matthew E Falagas
BMC Health Services Research , 2006, DOI: 10.1186/1472-6963-6-112
Abstract: We performed a retrospective analysis of data regarding house call visits of patients in the area of Attica (metropolitan area of Athens and surrounding cities), Greece. Characteristics of patients who received house call services by a physician, including diagnosis, and recommended management plan, including advice for hospitalization were analyzed.SOS doctors in the area of Attica, Greece performed 98,009 house calls during the 5-year study period (1/11/2000 – 31/10/2005). Patients older than 65 yeas requested 47.8% of the house calls. Females requested more house calls during the studied period compared to males (59.4% versus 40.6%, p < 0.001). The majority of the diagnoses (18.4%) were infections of the upper and lower respiratory tract. 9.1% of patients were advised after the evaluation at home to be admitted to a hospital to receive inpatient services.Our analysis documents the utilization of house calls by SOS doctors in the area of Attica, Greece during a 5-year period. We believe that house calls provided by individual practitioners, physician group practices, or organized companies and organizations should re-gain their well-deserved position in the modern health care systems.Physicians' patient house calls have been traditionally considered a vital part of an integrated health care system [1,2]. However, this type of medical care service has been declining for decades in several parts of the world, as shown by several studies that have been performed in various countries, such as the USA, Canada, and Slovenia [3-6]. It is interesting that in the USA, about 40% of physician-patient encounters involved house calls during the 1930s in contrast to less than 1% between 1998–2004 [7,8].There are several reasons that may explain the decreasing utilization of medical house call services. These may include improvement in medical transportation by ambulances, upgraded and efficient hospital facilities and their emergency departments, increased cost of house calls,
Epidemiology of constipation in Europe and Oceania: a systematic review
George Peppas, Vangelis G Alexiou, Eleni Mourtzoukou, Matthew E Falagas
BMC Gastroenterology , 2008, DOI: 10.1186/1471-230x-8-5
Abstract: Two reviewers performed PubMed searches and a hand search of references. A study was considered eligible for inclusion if it reported data about the prevalence of constipation in any population, free of other gastrointestinal disorders, in Europe and Oceania. Studies were evaluated for quality. Data regarding the setting, type of study, definition of constipation, study population, prevalence of constipation, factors associated with increased odds for constipation, and the female to male ratio, were collected.The 21 reviewed studies depict prevalence rates in 34 different population groups ranging widely from a low 0.7% to a high 81%. In the general population of Europe the mean value of the reported constipation rates is 17,1 % and the median value 16.6%. Among the studies conducted in Oceania, the mean value of constipation prevalence was 15.3%. Female gender, age and socioeconomic and educational class seem to have major effect on constipation prevalence. A number of various other risk factors are, less clearly, associated with constipation.This systematic review depicts the high prevalence and related risk factors of a disorder that decreases the health-related quality of life and has major economic consequences.Gastrointestinal functional disorders and especially constipation are common morbidity factors in otherwise healthy persons as well as in patients with various predisposing diseases. In the general population, constipation is frequently reported, resulting in 2.5 millions of physician visits in the United States [1] and a total health care cost of $2752 per patient treated [2]. The high prevalence rates, economic cost and adverse implications on the quality of life and health state [3,4], make constipation a major public health issue.Constipation is due to organic etiologies, such as mechanical obstruction, spinal cord injury [5], stroke, Parkinson's disease, hypothyroidism, diabetes [6] and local neurogenic disorders, e.g. Hirschsprung's disease [7] onl
Surveillance of Community Outbreaks of Respiratory Tract Infections Based on House-Call Visits in the Metropolitan Area of Athens, Greece
Alex Spanos, George Theocharis, Drosos E. Karageorgopoulos, George Peppas, Dimitris Fouskakis, Matthew E. Falagas
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040310
Abstract: Background The traditional Serfling-type approach for influenza-like illness surveillance requires long historical time-series. We retrospectively evaluated the use of recent, short, historical time-series for recognizing the onset of community outbreaks of respiratory tract infections (RTIs). Methods The data used referred to the proportion of diagnoses for upper or lower RTIs to total diagnoses for house-call visits, performed by a private network of medical specialists (SOS Doctors) in the metropolitan area of Athens, Greece, between January 01, 2000 and October 12, 2008. The reference standard classification of the observations was obtained by generating epidemic thresholds after analyzing the full 9-year period. We evaluated two different alert generating methods [simple regression and cumulative sum (CUSUM), respectively], under a range of input parameters, using data for the previous running 4–6 week period. These methods were applied if the previous weeks contained non-aberrant observations. Results We found that the CUSUM model with a specific set of parameters performed marginally better than simple regression for both groups. The best results (sensitivity, specificity) for simple regression and CUSUM models for upper RTIs were (1.00, 0.82) and (0.94, 0.93) respectively. Corresponding results for lower RTIs were (1.00, 0.80) and (0.93, 0.91) respectively. Conclusions Short-term data for house-call visits can be used rather reliably to identify respiratory tract outbreaks in the community using simple regression and CUSUM methods. Such surveillance models could be particularly useful when a large historical database is either unavailable or inaccurate and, thus, traditional methods are not optimal.
Do Psychological Variables Affect Early Surgical Recovery?
Michael N. Mavros,Stavros Athanasiou,Ioannis D. Gkegkes,Konstantinos A. Polyzos,George Peppas,Matthew E. Falagas
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0020306
Abstract: Numerous studies have examined the effect of psychological variables on surgical recovery, but no definite conclusion has been reached yet. We sought to examine whether psychological factors influence early surgical recovery.
The effect of psychosocial factors on breast cancer outcome: a systematic review
Matthew E Falagas, Effie A Zarkadoulia, Eleni N Ioannidou, George Peppas, Christos Christodoulou, Petros I Rafailidis
Breast Cancer Research , 2007, DOI: 10.1186/bcr1744
Abstract: We systematically searched the PubMed and PsycINFO databases to identify relevant studies.We identified 31 studies examining the association of various psychosocial parameters with overall breast cancer survival/disease free survival and 6 studies examining whether psychological intervention influences the disease outcome. Of the 31 studies summarized in this overview, 25 (80.6%) showed a statistically significant association between at least one psychosocial variable and disease outcome. Parameters associated with better breast cancer prognosis are social support, marriage, and minimizing and denial, while depression and constraint of emotions are associated with decreased breast cancer survival; however, the role of these factors has not been verified in all studies.Most of the studies show a significant relationship between psychosocial factors and survival, but the actual psychosocial variables related to survival are not consistently measured across studies and the findings for many of the psychosocial variables with survival/recurrence are not consistent across studies. Thus, more research is warranted regarding the role of social support, marriage, minimizing and denial, depression and constraint of emotions on breast cancer survival.Breast cancer is a significant cause of morbidity and mortality among women; it is the second leading cause of death due to cancer in women, exceeded only by lung cancer (American Cancer Society 2007) [1]. The fact that patients with apparently similar tumours at the time of presentation differ significantly in the time of relapse and overall survival implies that the determinants of survival could be broader than initially assumed in the purely medical framework. The question of whether psychosocial parameters could have an effect on the clinical outcome of cancer in general has yielded a large body of research devoted to this issue and has divided the medical community into believers and non-believers. We reviewed articles on t
Patients' Perception of Quality of Pre-Operative Informed Consent in Athens, Greece: A Pilot Study
Matthew E. Falagas,Patrick D. Akrivos,Vangelis G. Alexiou,Vasilios Saridakis,Theofanis Moutos,George Peppas,Barbara K. Kondilis
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0008073
Abstract: We sought to perform a study to record and evaluate patients' views of the way surgeons communicate informed consent (IC) in Greece.
Free Space Optical Communication with Spatial Modulation and Coherent Detection over H-K Atmospheric Turbulence Channels
Kostas P. Peppas,P. Takis Mathiopoulos
Mathematics , 2015, DOI: 10.1109/JLT.2015.2465385
Abstract: The use of optical spatial modulation (OSM), which has been recently emerged as a power and bandwidth efficient pulsed modulation technique for indoor optical wireless communication, is proposed as a simple, low-complexity means of achieving spatial diversity in coherent free space optical (FSO) communication systems. In doing so, this paper makes several novel contributions as follows. It presents a generic analytical framework for obtaining the Average Bit Error Probability (ABEP) of uncoded OSM with coherent detection in the presence of turbulence-induced fading. Although the framework is general enough to accommodate any type of models based on turbulence scattering, the focus in this paper is the H-K distribution. Although this distribution represents a very general scattering model valid over a wide range of atmospheric conditions, it is has not been considered in the past in conjunction with FSO systems possibly because of its mathematical complexity. The proposed analytical framework yields exact performance evaluation results for MIMO systems with two transmit- and an arbitrary number of receive apertures. In addition, tight upper bounds are derived for the error probability for OSM systems with an arbitrary number of transmit apertures as well as for convolutionally encoded signals. The performance of OSM is compared to that of well established coherent FSO schemes, employing spatial diversity at the transmitter or the receiver only. Specifically, it is shown that OSM can offer comparable performance with conventional coherent FSO schemes while outperforming the latter in terms of spectral efficiency and hardware complexity. Various numerical performance evaluation results are also presented and compared with equivalent results obtained by Monte Carlo simulations which verify the accuracy of the derived analytical expressions.
Famous persons with gastrointestinal, liver or pancreatic cancer
Th. Peppas,A. Sotiropoulos,J.K. Triantafillidis,S. Pappas
Annals of Gastroenterology , 2007,
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Performance Evaluation at the System Level of Reconfigurable Space-Time Coding Techniques for HSDPA
Kostas Peppas,Angeliki Alexiou,Fotis Lazarakis,Tareq Al-Gizawi
EURASIP Journal on Advances in Signal Processing , 2005, DOI: 10.1155/asp.2005.1656
Abstract: A reconfigurable space-time coding technique is investigated, for a high-speed downlink packet access multiple-antenna network, which combats the effects of antenna correlation. Reconfigurability is achieved at the link level by introducing a linear precoder in a space-time block coded system. The technique assumes knowledge of the long-term characteristics of the channel, namely the channel correlation matrix at the transmitter. The benefits of the proposed reconfigurable technique as compared to the conventional non-reconfigurable versions are evaluated via system-level simulations. In order to characterize the system-level performance accurately and, at the same time, use a feasible approach in terms of computational complexity, a suitable link-to-system interface has been developed. The average system throughput and the number of satisfied users are the performance metrics of interest. Simulation results demonstrate the performance enhancements achieved by the application of reconfigurable techniques as compared to their conventional counterparts.
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