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Search Results: 1 - 10 of 1092 matches for " Natalie Baddour "
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Multidimensional Wave Field Signal Theory: Transfer Function Relationships
Natalie Baddour
Mathematical Problems in Engineering , 2012, DOI: 10.1155/2012/478295
Abstract: The transmission of information by propagating or diffusive waves is common to many fields of engineering and physics. Such physical phenomena are governed by a Helmholtz (real wavenumber) or pseudo-Helmholtz (complex wavenumber) equation. Since these equations are linear, it would be useful to be able to use tools from signal theory in solving related problems. The aim of this paper is to derive multidimensional input/output transfer function relationships in the spatial domain for these equations in order to permit such a signal theoretic approach to problem solving. This paper presents such transfer function relationships for the spatial (not Fourier) domain within appropriate coordinate systems. It is shown that the relationships assume particularly simple and computationally useful forms once the appropriate curvilinear version of a multidimensional spatial Fourier transform is used. These results are shown for both real and complex wavenumbers. Fourier inversion of these formulas would have applications for tomographic problems in various modalities. In the case of real wavenumbers, these inversion formulas are presented in closed form, whereby an input can be calculated from a given or measured wavefield.
Multidimensional wave field signal theory: Mathematical foundations
Natalie Baddour
AIP Advances , 2011, DOI: 10.1063/1.3596359
Abstract: Many important physical phenomena are described by wave or diffusion-wave type equations. Since these equations are linear, it would be useful to be able to use tools from the theory of linear signals and systems in solving related forward or inverse problems. In particular, the transform domain signal description from linear system theory has shown concrete promise for the solution of problems that are governed by a multidimensional wave field. The aim is to develop a unified framework for the description of wavefields via multidimensional signals. However, certain preliminary mathematical results are crucial for the development of this framework. This first paper on this topic thus introduces the mathematical foundations and proves some important mathematical results. The foundation of the framework starts with the inhomogeneous Helmholtz or pseudo-Helmholtz equation, which is the mathematical basis of a large class of wavefields. Application of the appropriate multi-dimensional Fourier transform leads to a transfer function description. To return to the physical spatial domain, certain mathematical results are necessary and these are presented and proved here as six fundamental theorems. These theorems are crucial for the evaluation of a certain class of improper integrals which arise in the evaluation of inverse multi-dimensional Fourier and Hankel transforms, upon which the framework is based. Subsequently, applications of these theorems are demonstrated, in particular for the derivation of Green's functions in different coordinate systems.
Signal processing of heart signals for the quantification of non-deterministic events
Véronique Millette, Natalie Baddour
BioMedical Engineering OnLine , 2011, DOI: 10.1186/1475-925x-10-10
Abstract: An algorithm is presented for the quantification of high-frequency, non-deterministic events such as cavitation from recorded signals. A closed-form mathematical analysis of the algorithm investigates its capabilities. The algorithm is implemented on real heart signals to investigate usability and implementation issues. Improvements are suggested to the base algorithm including aligning heart sounds, and the implementation of the Short-Time Fourier Transform to study the time evolution of the energy in the signal.The improvements result in better heart beat alignment and better detection and measurement of the random events in the heart signals, so that they may provide a method to quantify nondeterministic events in heart signals. The use of the Short-Time Fourier Transform allows the examination of the random events in both time and frequency allowing for further investigation and interpretation of the signal.The presented algorithm does allow for the quantification of nondeterministic events but proper care in signal acquisition and processing must be taken to obtain meaningful results.Listening to the heart is perhaps the most important, basic, and effective clinical technique for evaluating a patient's cardiovascular function. A skilled practitioner can quickly evaluate common complaints that may be quite serious. In recent years, there has been an interest in applying signal processing techniques to aid in the detection, analysis and quantification of various aspects of interest in heart signals. Signal processing can be used to automate the measurement of various signal characteristics, reducing subjectivity and increasing reliability. Another purpose is to filter out undesired signal components with either technical or physiological origin so that analysis of the relevant portion of the signal is facilitated. For example, some analyses have focused on attempting to identify valve abnormality [1,2], heart rate variability [3-5], to detect heart pathologies [6
Improving Laboratory Test-Ordering with Information Technology  [PDF]
Adnan Ali Baddour, Anas Serag Dablool, Saeed Saeed Al-Ghamdi
International Journal of Clinical Medicine (IJCM) , 2012, DOI: 10.4236/ijcm.2012.36083
Abstract: The overuse of clinical laboratory services has been documented for many years. This overuse use does not contribute to the quality of medical care, does not shorten hospital stay, nor reduce mortality. The utilization of diagnostic laboratories has increased over the last decade around the world. This increased laboratory use is appropriate if it allows accurate diagnoses to be made, ideal treatment to be identified and monitored, accurate prognoses to be established, and patients’ hospital stays to be shortened. Thus, improving the appropriateness of testing behavior and reducing the number of laboratory tests have been recognized as essential parts of quality improvement program. In this study, the effectiveness of a computer-based system in improving the laboratory test-ordering in a general hospital was investigated. The study was conducted through four stages, the preparation stage, the pre-intervention stage, the post-intervention 1) stage and post-intervention 2) stage. Guideline and computer system were developed during preparation stage. Medical records were reviewed against guideline recommendations before any intervention during the pre-intervention stage, after guideline dissemination through educational workshops during the post intervention 1) stage, and after implementation of the computer system with the new requesting form during the post intervention 2) stage. The study revealed that the computer-based system achieved a statistically significant increase in the percentage of appropriate use from 44.6% in the post-intervention 1) stage to 55.6%, and a statistically significant increase in the compliance with guideline by prescriber as well as increased in guideline conformity rate from 16.7% in the post-intervention 1) stage to 32.5% in the post-intervention 2) stage, and decreased in the percentage of prescribers whose level was unsatisfactory from 85.4% the post-intervention 1) stage to 66.7% in the post-intervention 2) stage.
Trends in antibiotic susceptibility patterns and epidemiology of MRSA isolates from several hospitals in Riyadh, Saudi Arabia
Manal M Baddour, Manal M Abuelkheir, Amal J Fatani
Annals of Clinical Microbiology and Antimicrobials , 2006, DOI: 10.1186/1476-0711-5-30
Abstract: A total of 512 MRSA isolates were procured from 6 major hospitals in Riyadh, Saudi Arabia and antibiotic susceptibilities and MICs were documented against several antibiotics and vancomycin. SPSS version 10 was used for statistical analysis.The prevalence of MRSA in the study hospitals ranged from 12% to 49.4%. Mean patient age was 44 years with males constituting 64.4% and females 35.6%. Approximately 41.5% of the isolates came from patients in the extreme age groups. MIC for vancomycin was in the susceptible range for all isolates ranging from 0.25 to 3 ug/ml. The overall susceptibility of MRSA to the various antibiotics tested was: fusidic acid 4.3%, sulfamethoxazole/trimethoprim 33.8%, gentamicin 39.6%, mupirocin 77.0%, gatifloxacin 78.9%, chloramphenicl 80.7%, linezolid 95.1%, quinupristin/dalfopristin 100%. Some differences were noted in the resistance of isolates among the participating hospitals reflecting antibiotic usage. On the whole, inpatient isolates (accounting for 77.5% of the isolates) were more resistant than outpatient isolates (22.5%) except for linezolid. Quinupristin-dalfopristin and linezolid are the most effective antibiotics tested against inpatient isolates while quinupristin-dalfopristin and gatifloxacin seem to be the most effective against outpatient isolates.Approximately one forth of the isolates are no longer susceptible to mupirocin used for eradication of the carrier state reflecting resistance developing after widespread use. Trends over time show a tendency towards decreased susceptibility to gatifloxacin and linezolid with increasing susceptibility to gentamicin and sulfamethoxazole/trimethoprim.Quinupristin/dalfopristin and linezolid are two valuable additions to our antimicrobial armamentarium, but resistance has already been described. To preserve their value, their use should be limited to those rare cases where they are clearly needed. Fusidic acid, the local antibiotic, gentamicin and trimethoprim/sulfamethoxazole should no
Gremlin in the pathogenesis of hepatocellular carcinoma complicating chronic hepatitis C: an immunohistochemical and PCR study of human liver biopsies
Maha Guimei, Nahed Baddour, Dalal ElKaffash, Laila Abdou, Yousry Taher
BMC Research Notes , 2012, DOI: 10.1186/1756-0500-5-390
Abstract: Protein expression of cytokeratin 19 (CK19) and fibroblast growth factor 2 (FGF-2), and mRNA expression of gremlin and BMP-7 were studied in 35 cases of chronic hepatitis, cirrhosis and HCC complicating chronic hepatitis C. CK19 expression was higher in cases of cirrhosis (0.004), which correlated with the grade (r?=?0.64, p?=?0.009) and stage (r?=?0.71, p?=?0.001). All HCCs were negative for CK19. Stem cell niche activation (as indicated as a ductular reaction) was highest in cases of cirrhosis (p?=?0.001) and correlated with CK19 expression (r?=?0.42, p?=?0.012), the grade(r?=?0.56, p?=?0.024) and stage (0.66, p?=?0.006). FGF-2 expression was highest in HCCs and correlated with the grade (r?=?0.6, p?=?0.013), stage (0.72, p?=?0.002), CK19 expression (r?=?0.71, p?=?002) and ductular reaction (0.68, p?=?0.004) in hepatitis cases. Higher numbers of cirrhosis cases and HCCs (p?=?0.009) showed gremlin expression, which correlated with the stage (r?=?0.7, p?=?0.002). Gremlin expression correlated with that of CK19 (r?=?0.699, p?=?0.003) and FGF2 (r?=?0.75, p?=?0.001) in hepatitis cases.Fibrosis promotes carcinogenesis by fibroblast-secreted gremlin that blocks BMP function and promotes stem cell activation and proliferation as well as possibly HCC development.The variability in the prognosis of individuals with hepatocellular carcinoma (HCC) suggests that HCC may comprise several distinct biological phenotypes. These phenotypes may result from activation of different oncogenic pathways during tumorigenesis and/or a different cell of origin [1]. Enhanced proliferation and maturation arrest of hepatic progenitor/stem cells have been considered the origin of HCCs [1]. However, the link between cirrhosis and stem cell proliferation has not been fully elucidated. This link is multifaceted and complex with interplay of multiple factors that enhance or inhibit the proliferative rate of hepatic progenitor/stem cells, which culminates in HCC development. The outcome depends on t
?Qué significa Medicina Basada en Evidencia?
Simonovis,N; Baddour P,Y; García,S; Madera,C;
Revista de la Facultad de Medicina , 2001,
Abstract: this paper critically review the meaning of evidence-based medicine. the study begins with thomas kuhn?s definition of paradigm and, according to the context it provides, the reason why evidence based medicine constitutes a change of paradigm. after an evaluation of the two main dissenting perspectives of the above mentioned paradigm it goes on to solve the controversy by means of an analysis of the phenomenology of knowledge and the etymology of the word evidence. it then concludes with the authors own position.
Miltefosine for Old World cutaneous leishmaniasis: An experimental study on Leishmania major infected mice
MM Eissa, EI Amer, SF Mossallam, MM Gomaa, NM Baddour
Alexandria Journal of Medicine , 2012,
Abstract: Background: Leishmaniasis is one of the neglected diseases included in the World Health Organization’s list of the top guns of antimicrobial resistance. Miltefosine (MIL) was the first successful oral agent used against visceral leishmaniasis in India. As regards cutaneous leishmaniasis (CL), multiple experimental and clinical studies have investigated its efficacy in treatment of New World CL, while only few trials have focused on Old World CL. Therefore, this work was designed to study the efficacy of MIL in experimental Old World CL caused by Leishmania major (MHOM/IL/81/FEBNI), one of the causative species of CL in the Middle East. Results: Groups of infected mice were given MIL orally, at a dose of 20 mg/kg/day for 20 days. Results showed that untreated infected mice suffered from autoamputation of the inoculated footpads. While, those treated with MIL showed complete clinical cure, significant reduction of parasite burden and improvement of the histopathological changes of the cutaneous lesions. The drug causes evident ultrastructural morphological alterations of L. major amastigote form. One month posttreatment, no clinical sings of relapse were observed, and parasite density continued to decrease significantly. Conclusion: The present study revealed activity of MIL against experimental Old World CL in the mouse model caused by L. major (MHOM/IL/81/FEBNI), one of the causative species of CL in the Middle East.
Qué significa Medicina Basada en Evidencia?
N Simonovis,Y Baddour P,S García,C Madera
Revista de la Facultad de Medicina , 2001,
Abstract: El presente artículo revisa críticamente el significado de la medicina basada en evidencia. El estudio comienza definiendo el concepto de paradigma de acuerdo a Thomas Khun y dentro de este contexto por qué la medicina basada en evidencia constituye un cambio de paradigma. Después de evaluar las dos principales perspectivas discrepantes del paradigma arriba se alado resuelve la controversia mediante el análisis etimológico de la palabra evidencia y la fenomenología del conocimiento para luego concluir con una posición propia de los autores. This paper critically review the meaning of evidence-based medicine. The study begins with Thomas Kuhn’s definition of paradigm and, according to the context it provides, the reason why evidence based medicine constitutes a change of paradigm. After an evaluation of the two main dissenting perspectives of the above mentioned paradigm it goes on to solve the controversy by means of an analysis of the phenomenology of knowledge and the etymology of the word evidence. It then concludes with the authors own position.
Voices from the Land: Reflections on Teenaged Pregnancy in Aboriginal Communities Today - The Voices of Traditional Healers
Delores Cardinal,Clifford Cardinal,Earle Waugh,Darryn Baddour
International Indigenous Policy Journal , 2013,
Abstract: While the precarious state of Aboriginal health is often noted, and several studies have detailed the issues raised by teenage pregnancy, the voices from traditional healers, many of whom have to deal with the youth are scarcely recorded. These reflections are in response to the conversation of select traditional practitioners at The Gathering, held in the Faculty of Medicine and Dentistry, the University of Alberta, in October, 2010. They spent about one-and-a-half hours discussing the issue with health care professionals and physicians. This article reprises high points of that discussion along with additional material offered to support their contentions.
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