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Search Results: 1 - 10 of 466059 matches for " Hassan A. Tarraf "
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Tensor Product of Krammer’s Representations of the P3  [PDF]
Hassan A. Tarraf, Mohammad N. Abdulrahim
Advances in Pure Mathematics (APM) , 2012, DOI: 10.4236/apm.2012.23026
Abstract: We consider the complex specializations of Krammer’s representation of the pure braid group on three strings, namely K(q,t), where q and t are non-zero complex numbers. We then specialize the indeterminate t by one and replace by for simplicity. Then we present our main theorem that gives us sufficient conditions that guarantee the irreducibility of the tensor product of two irreducible complex specializations of Krammer’s repre- sentations .
Higher Dimensional Irreducible Representations of the Pure Braid Group
Mohammad N. Abdulrahim,Hassan A Tarraf
Journal of Mathematics Research , 2011, DOI: 10.5539/jmr.v3n4p141
Abstract: The reduced Gassner representation is a multi-parameter representation of $% P_{n},$ the pure braid group on n strings. Specializing the parameters $% t_{1},t_{2},...,t_{n}$ to nonzero complex numbers $x_{1},x_{2},...,x_{n}$ gives a representation $G_{n}(x_{1},ldots ,x_{n}):P_{n} ightarrow GL(mathbb{C}^{n-1})$ which is irreducible if and only if $x_{1}ldots x_{n} eq 1$. In a previous work, we found a sufficient condition for the irreducibility of the tensor product of two irreducible Gassner representations. In our current work, we find a sufficient condition that guarantees the irreducibility of the tensor product of three Gassner representations. Next, a generalization of our result is given by considering the irreducibility of the tensor product of $k$ representations (;$k geq 3;$).
Finite Approximations of Switched Homogeneous Systems for Controller Synthesis
Danielle C. Tarraf,Alexandre Megretski,Munther A. Dahleh
Mathematics , 2009, DOI: 10.1109/TAC.2011.2108350
Abstract: We demonstrate the use of a new, control-oriented notion of finite state approximation for a particular class of hybrid systems. Specifically, we consider the problem of designing a stabilizing binary output feedback switching controller for a pair of unstable homogeneous second order systems. The constructive approach presented in this note, in addition to yielding an explicit construction of a deterministic finite state approximate model of the hybrid plant, allows us to efficiently establish a useable upper bound on the quality of approximation, and leads to a discrete optimization problem whose solution immediately provides a certifiably correct-by-design controller for the original system. The resulting controller consists of a finite state observer for the plant and a corresponding full state feedback switching control law.
Assessment of the Socio-Demographic Factors Associated with the Satisfaction Related to the Childbirth Experience  [PDF]
Elie Al Ahmar, Samir Tarraf
Open Journal of Obstetrics and Gynecology (OJOG) , 2014, DOI: 10.4236/ojog.2014.410083

Assessment of the socio-demographic factors associated with the satisfaction is related to the childbirth experience. Objective: A mother’s satisfaction with the childbirth experience may have instant and lasting effects on her wellbeing, and on the bonding with her infant. The main aim of the study was to assess which socio-demographic factors are associated with this satisfaction. Most factors that authors agree on are: Pain intensity, personal control, self-efficacy, length of labor, method of delivery and numerous other demographic factors. Design: A cross-sectional study. Data was collected using a self-reported survey. Settings: The sample consisted of 100 women, selected from St Georges Hospital and CHU-NDS, who had to speak Arabic and had given birth in the past three days prior to interview. Methods: The multiple linear regressions and the mean test were used to assess which factors were associated with a positive childbirth experience. The Mackey childbirth satisfaction scale, three items from the Wijma delivery Expectancy/Experience questionnaire, a seven item mastery scale developed by Pearlin and Schooler and a background questionnaire were filled by women. Findings: Factors that were linked to a positive birth experience were: Higher age, multiparous women, higher education, high monthly income, unemployment, childbirth preparation, high personal control and self-efficacy, high childbirth and labor pain, fulfilled expectations, shorter period of labor and instrumented delivery. Conclusion: This study demonstrates that satisfaction with the childbirth experience is multi-dimensional with diverse factors foreseeing diverse dimensions of satisfaction.

Geochemical Characteristics and Chemical Electron Microprobe U-Pb-Th Dating of Pitchblende Mineralization from Gabal Gattar Younger Granite, North Eastern Desert, Egypt  [PDF]
Hassan A. A. Shahin
Open Journal of Geology (OJG) , 2014, DOI: 10.4236/ojg.2014.41003

Pitchblende mineralization was studied in the younger granite samples collected from Gabal Gattar, north Eastern Desert, Egypt using electron scanning microscope (ESM) and electron probe microanalyses (EPMA). This study revealed that this pitchblende contains significant Zr content reaching up to (66.80% ZrO2), which suggests that volcanic rocks were probably the source of such a deposit. High level emplaced high-K Calc-alkaline plutons as Qattar granite may have been associated with their volcanic equivalent emplaced in the surrounding area or now eroded. Lead content of the pitchblende mineralization is high and with moderate volcanics (up to 7.71% PbO). In contrast, it is low in ThO2, Y2O3 and REE2O3. High Zr and Pb content associated with pitchblende mineralization from Gattar granite indicates

Ultrastructural Identification of the Basal-Granulated Cells in the Duodenum of Albino Rat  [PDF]
Ali Hassan A. Ali
Open Journal of Gastroenterology (OJGas) , 2014, DOI: 10.4236/ojgas.2014.47041
Abstract: The fine structure of the crypt epithelium of the duodenal mucosa in albino rats was studied to represent the types and distribution of the basal-granulated or endocrine cells. Twenty male animals were used. Perfusion-fixation was made and samples of duodenal mucosa were taken and processed to prepare epon-embedded specimens for examination by a transmission electron microscope. Cells containing membrane-bound granules were seen in the crypt epithelium. They were identified to be basal-granulated cells. Six different types of such cells were demonstrated. All of the cells were of the closed type. The possible functional significance of these closed cell types was discussed. Correlation among the distributions of such cells in the intestine of albino rat might enable the physiologists, internists and other research workers to study several biologically active peptides with well-established functions other than those which have long been investigated.
Hepatoprotective Effect of Green Tea Extract against Cyclophosphamide Induced Liver Injury in Albino Rats  [PDF]
Ali Hassan A. Ali
Forensic Medicine and Anatomy Research (FMAR) , 2018, DOI: 10.4236/fmar.2018.62002
Abstract: Background: Green tea intake is accompanied with a lower incidence of cardiovascular disease, cancer and neurodegenerative disorders; hence green tea extract has been included as dietary supplement along with other supplements and multivitamins. Aim of the Work: Studying the effect of cyclophosphamide administration on the liver of adult male albino rats and the possible protective role of green tea extract. Material and Methods: The current study was carried out on 45 adult male albino rats. They were divided into three equal groups (each included 15 rats). Group I (control group) was injected intraperitoneally with normal saline at a dosage of 0.5 mg/kg body weight twice weekly for 9 weeks. Group II was injected intraperitoneally with cyclophosphamide (CP) (150 mg/kg/day) for two weeks. Group III: rats received green tea extracts orally (50 mg/kg/day) for three weeks, and then continued for further two weeks concomitantly with intraperitoneally cyclophosphamide (CP) injected (150 mg/kg/day). Results: Rats exposed to cyclophosphamide (CP) showed several histological and histochemical changes in their liver. These changes were improved by using green tea. Conclusion: The present work showed that green tea had preventive and therapeutic effect upon livers of albino rats after they were exposed to CP.
Travail et déni de travail : les Palestiniens de Tripoli et des camps de réfugiés (Nahr al Bared, Beddawi) au Nord du Liban Work and denial of work: Palestinians in Tripoli and in Northern Lebanon refugee camps
Souha Tarraf-Najib
Revue des Mondes Musulmans et de la Méditerranée , 2012, DOI: 10.4000/remmm.2731
Abstract: Que signifie aujourd’hui être Palestinien au Liban ? à partir de cette question, l’étude présente de fa on synthétique la situation sociale, politique et économique des réfugiés palestiniens au Liban, qui habitent encore en majorité dans des “camps”, depuis 1948. D’une période de relative sécurité sociale, économique et politique, durant les “années OLP” (1969-82), la population palestinienne du Liban est passée après 1982 et plus encore après 1993 (accords d’Oslo), à une réelle insécurité à tous points de vue, travail, santé, etc. Marginalisés voire rejetés par la société et l’establishment libanais, soumis à la forte concurrence d’une main-d’oeuvre étrangère très présente dans le marché du travail libanais, les Palestiniens du Liban sont dans l’impasse. What does it mean to be a Palestinian in Lebanon today ? With this simple question in mind, this research will examine the socio-economic and political situation of the Palestinians who have been living in Lebanese “refugee camps” since 1948. Following a period of relative tranquillity and socio-political stability during the PLO years, between 1969 and 1982, the Palestinian people of Lebanon have had to endure a very unstable and insecure situation since 1982 and even more so after 1993 (Oslo treaty). Victimized and marginalized by the Lebanese regime and society, and at the same time competing with a dominant foreign labour force who controls the blue-collar market in Lebanon, the Palestinians of Lebanon are at a standstill.
An Input-Output Construction of Finite State $ρ/μ$ Approximations for Control Design
Danielle C. Tarraf
Mathematics , 2013,
Abstract: We consider discrete-time plants that interact with their controllers via fixed discrete alphabets. For this class of systems, and in the absence of exogenous inputs, we propose a general, conceptual procedure for constructing a sequence of finite state approximate models starting from finite length sequences of input and output signal pairs. We explicitly derive conditions under which the proposed construct, used in conjunction with a particular generalized structure, satisfies desirable properties of $\rho/\mu$ approximations thereby leading to nominal deterministic finite state machine models that can be used in certified-by- design controller synthesis. We also show that the cardinality of the minimal disturbance alphabet that can be used in this setting equals that of the sensor output alphabet. Finally, we show that the proposed construct satisfies a relevant semi-completeness property.
A Control-Oriented Notion of Finite State Approximation
Danielle C. Tarraf
Mathematics , 2011, DOI: 10.1109/TAC.2012.2199180
Abstract: We consider the problem of approximating discrete-time plants with finite-valued sensors and actu- ators by deterministic finite memory systems for the purpose of certified-by-design controller synthesis. Building on ideas from robust control, we propose a control-oriented notion of finite state approximation for these systems, demonstrate its relevance to the control synthesis problem, and discuss its key features.
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