In this work, Laser Induced Breakdown Spectroscopy (LIBS) was used to determine the constituent of Gum Arabic (Acacia nilotica) collected from five different locations in Sudan. Gum samples were irradiated with 80 mJ pulse energy of... more
In this work, Laser Induced Breakdown Spectroscopy (LIBS) was used to determine the constituent of Gum Arabic (Acacia nilotica) collected from five different locations in Sudan. Gum samples were irradiated with 80 mJ pulse energy of Nd-YAG laser (1064 nm) and Atomic spectra Database was used for the spectral analysis of the plasma emitted from these samples. It was found that the samples contain the elements C, O, H, S, N, P, Na, Mg, Ca, Fe, Cr, Mn, Co with different amounts. Some elements like (Ti, Br, Ar, Th, Kr, Sc and Pr) are recorded here for the first time.
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Essential thrombocythemia (ET) is a neoplastic proliferation of mature myeloid cells - in particular, megakaryocytes - leading to persistently elevated platelet count. Usual clinical presentation is related to an increase in the risk of... more
Essential thrombocythemia (ET) is a neoplastic proliferation of mature myeloid cells - in particular, megakaryocytes - leading to persistently elevated platelet count. Usual clinical presentation is related to an increase in the risk of hemorrhage and/or thrombosis. Management of ET consists of antiplatelet therapies - mainly aspirin and cytoreductive therapies. Coronary involvement in patients with ET is rare. The optimal treatment strategies for ET patients presenting with acute myocardial infarction remains unclear. Acute interventions like intracoronary thrombolytic therapy, angioplasty, and coronary-artery bypass grafting have been reported in such patients. However, several questions remain unanswered about the acute and long-term management of these patients. Herein, we report the case of a 47-year-old female who presented with acute myocardial infarction as the first clinical sign of ET, and also present the long-term follow-up of this patient.
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Telecommunication technology has become a very crucial method of communication nowadays in all countries. However, there many concerns regarding the safety and biological risk from telecommunications towers. This study aims to analyze the... more
Telecommunication technology has become a very crucial method of communication nowadays in all countries. However, there many concerns regarding the safety and biological risk from telecommunications towers. This study aims to analyze the number and distribution of the base transceiver station (BTS) in Khartoum state and assess the possible biological risk. Khartoum State was divided into seven districts are calculated and compared with the Ministry of Communications. This study's results were obtained from the Telecommunication companies (A, B, and C) operating in the Khartoum State (. Khartoum state has 2214 BTs distributed in its seven districts (area =22,142 km2). The largest number of antennas was found in Khartoum, with 515 antennas, at 23 %, and the lowest in the district is Karari districts, with only 206(9%). The number of BTS in company A has 10 locations, 0.1% and None share 817 , 99% ,In Company B =492 location ,share lactation 233,47.35% ,Non Share 259(52.6%) and the Company C has 791 Locations, Share location= 695 (87.8%) , Non share has 200 (25.28%). According to the companies operation, the mean share locations in Khartoum state 45.3%, and Non-share locations are 59%. The study revealed that the number of non-shared antennas in the state of Khartoum is greater than the common antennas, and therefore, the resulting emitted power is less than the Share antennas. The current number of BTs comply with international guidelines. Based on the distribution of BTs, the risk is minimal to the general population.
The nature and origin of the photon and elementary rest masses are some of the challenging problems that physics face. The approaches used to solve these problems are complex and time-consuming. Specifically, the photon rest mass pays... more
The nature and origin of the photon and elementary rest masses are some of the challenging problems that physics face. The approaches used to solve these problems are complex and time-consuming. Specifically, the photon rest mass pays attention to theoretical physicists. Many experimental works show that the photon rest mass is non zero. This problem can be solved using generalized potential dependent special relativity, which has been derived using simple arguments, and Maxwell's equations, besides the conventional Einstein energy momentum relation. The results obtained show that the rest mass of photons and elementary particles are strongly dependent on the vacuum energy and a universal constant. This result conforms with the models that predict time decaying vacuum energy associated with production of smaller rest mass particles followed by larger masses. The two potential dependent mass expressions conform with the cosmological models that suggest the photon is generated first by assuming the universe consisting of total constant vacuum with decaying cosmological part and mass generating part. Using Maxwell's equations, beside plank and De Broglie hypothesis together with special relativity energy-momentum relation the photon rest mass is estimated. It was shown that the photon rest mass is extremely small Open Access https://doi.org/10.4236/ns.2020.128045 589 Natural Science compared to the electron mass.
The nature and origin of the photon and elementary rest masses are some of the challenging problems that physics face. The approaches used to solve these problems are complex and time-consuming. Specifically, the photon rest mass pays... more
The nature and origin of the photon and elementary rest masses are some of the challenging problems that physics face. The approaches used to solve these problems are complex and time-consuming. Specifically, the photon rest mass pays attention to theoretical physicists. Many experimental works show that the photon rest mass is non zero. This problem can be solved using generalized potential dependent special relativity, which has been derived using simple arguments, and Maxwell's equations, besides the conventional Einstein energy momentum relation. The results obtained show that the rest mass of photons and elementary particles are strongly dependent on the vacuum energy and a universal constant. This result conforms with the models that predict time decaying vacuum energy associated with production of smaller rest mass particles followed by larger masses. The two potential dependent mass expressions conform with the cosmological models that suggest the photon is generated first by assuming the universe consisting of total constant vacuum with decaying cosmological part and mass generating part. Using Maxwell's equations, beside plank and De Broglie hypothesis together with special relativity energy-momentum relation the photon rest mass is estimated. It was shown that the photon rest mass is extremely small Open Access https://doi.org/10.4236/ns.2020.128045 589 Natural Science compared to the electron mass.
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Plank quantum and classical string energy relations seem to be uncorrelated. This work correlated them. The relativistic energy-momentum relation has been used together with plank and de Brogglie hypothesis to prove that the wave group... more
Plank quantum and classical string energy relations seem to be uncorrelated. This work correlated them. The relativistic energy-momentum relation has been used together with plank and de Brogglie hypothesis to prove that the wave group velocity is equal to the particle velocity in both ordinary and curved space. The plank energy relation is shown also to be related to the classical energy relation of an oscillating string. Starting from plank energy relation for n photons and performing integration, the expression of classical string energy was obtained. This means that one can treat electromagnetic waves as a collection of continuous photons having frequencies ranging from zero to w. Conversely, starting from classical string energy relation by differentiating it with respect to angular frequency, the plank quantum energy for n photons has been found. This means that the quanta results from separation of electromagnetic waves to single are orated waves. Each wave consists of n pho-tons or quanta.
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Plank quantum and classical string energy relations seem to be uncorrelated. This work correlated them. The relativistic energy-momentum relation has been used together with plank and de Brogglie hypothesis to prove that the wave group... more
Plank quantum and classical string energy relations seem to be uncorrelated. This work
correlated them. The relativistic energy-momentum relation has been used together with
plank and de Brogglie hypothesis to prove that the wave group velocity is equal to the particle velocity in both ordinary and curved space. The plank energy relation is shown also to
be related to the classical energy relation of an oscillating string. Starting from plank energy
relation for n photons and performing integration, the expression of classical string energy
was obtained. This means that one can treat electromagnetic waves as a collection of continuous photons having frequencies ranging from zero to w. Conversely, starting from classical string energy relation by differentiating it with respect to angular frequency, the plank
quantum energy for n photons has been found. This means that the quanta results from separation of electromagnetic waves to single are orated waves. Each wave consists of n photons or quant
correlated them. The relativistic energy-momentum relation has been used together with
plank and de Brogglie hypothesis to prove that the wave group velocity is equal to the particle velocity in both ordinary and curved space. The plank energy relation is shown also to
be related to the classical energy relation of an oscillating string. Starting from plank energy
relation for n photons and performing integration, the expression of classical string energy
was obtained. This means that one can treat electromagnetic waves as a collection of continuous photons having frequencies ranging from zero to w. Conversely, starting from classical string energy relation by differentiating it with respect to angular frequency, the plank
quantum energy for n photons has been found. This means that the quanta results from separation of electromagnetic waves to single are orated waves. Each wave consists of n photons or quant
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Sudan.Abstract Using generalized special relativistic energy-momentum relation the linear energy-momentum Dirac relation was obtained. This equation was used to find Dirac generalized relativistic quantum equation. This equation was used... more
Sudan.Abstract Using generalized special relativistic energy-momentum relation the linear energy-momentum Dirac relation was obtained. This equation was used to find Dirac generalized relativistic quantum equation. This equation was used to find the probability and the number of particles for each atomic energy level. The wave function found using this equation can give an expression for the number of electrons in each energy levels if the atomic radius is quantized and satisfy a certain relation.
A pressure dependent Schrodinger equation is used to find the conditions that lead to su-perconductivity. When no pressure is exerted, the superconductor resistance vanishes beyond a critical temperature related to the repulsive force... more
A pressure dependent Schrodinger equation is used to find the conditions that lead to su-perconductivity. When no pressure is exerted, the superconductor resistance vanishes beyond a critical temperature related to the repulsive force potential of the electron gass, where one assuming the electron total energy to be thermal, where applying mechanical pressure destroys Sc when it exceeds a certain critical value. However when the electron total energy is an assumed to be that of the free electron model and that the pressure is thermal and mechanical , the situation is different. The quantum expression for resistance shows that the increase of mechanical pressure increases the critical temperature. Such phenomenon is observed in high temperature cupper group.
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Using Quasi‐Monoenergetic Photon Sources To Probe Photo‐Fission Resonances. [AIP Conference Proceedings 1336, 590 (2011)]. Micah S. Johnson, James M. Hall, Dennis P. McNabb, Michael J. Tuffley, Mohammed W. Ahmed ...
to study correlation of obstructive sleep apnea (OSA)and laryngo-pharyngeal reflux (LPR). A descriptive study. Suez Canal University Hospital, Ismailia, Egypt. 62 patients with polysomnography confirmed OSA. patients were evaluated with... more
to study correlation of obstructive sleep apnea (OSA)and laryngo-pharyngeal reflux (LPR). A descriptive study. Suez Canal University Hospital, Ismailia, Egypt. 62 patients with polysomnography confirmed OSA. patients were evaluated with ambulatory 24-hour double channel pH monitoring. Mean reflux symptom index in the study group was 9+5.5 and it was > 13 in all patients with severe OSA. Signs of LPR reflux were present in 34 (55%) patients. Abnormal reflux was detected in the distal esophagus in 41 patients (66%) and in the proximal esophagus in 21 patients (34%). Patients with severe OSA had significantly higher nocturnal LPRreflux episodes compared to patients with mild disease (p<.05). Number of reflux episodes and total duration of reflux during sleep are significantly correlated to degree of OSA (p< .05). No difference was found in relation to age or sex. Daytime reflux was not related to the degree of obstructive sleep apnea (p> .05). LPR is common in patients with...
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Recurrent anterior instability is a common finding after traumatic glenohumeral dislocation in the young, athletic patient population. A variety of concomitant pathologies may be present in addition to the classic Bankart lesion,... more
Recurrent anterior instability is a common finding after traumatic glenohumeral dislocation in the young, athletic patient population. A variety of concomitant pathologies may be present in addition to the classic Bankart lesion, including glenoid bone loss; humeral head bone loss; rotator interval pathology; complex/large capsular injuries including humeral avulsions of the glenohumeral ligaments (HAGL lesions), SLAP tears, near circumferential labral tears, and anterior labral periosteal sleeve avulsions (ALPSA lesions); and rotator cuff tears. Normal anatomic variations masquerading as pathology also may be present. Recognition and treatment of these associated pathologies are necessary to improve function and symptoms of pain and to confer anterior shoulder stability. This review will focus on the history, physical examination findings, imaging findings, and recommended treatment options for common sources of copathology in anterior shoulder instability repair.
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Salmeterol/fluticasone combination (SFC) formulated in a breath-actuated inhaler (BAI) overcomes the co-ordination problem associated with the pressurized-metered dose inhaler (pMDIs). Our aim was to compare the efficacy and the safety of... more
Salmeterol/fluticasone combination (SFC) formulated in a breath-actuated inhaler (BAI) overcomes the co-ordination problem associated with the pressurized-metered dose inhaler (pMDIs). Our aim was to compare the efficacy and the safety of SFC given through the BAI versus the conventional pMDI in moderate-to-severe asthmatics. In this randomized, double-blind, double-dummy, prospective, active-controlled, parallel group, multicenter, 12 weeks study, 150 asthmatics were randomized to receive SFC (25/125 mcg) through either BAI or pMDI. The primary efficacy endpoint was mean change in pre-dose morning PEFR value at 12 weeks and the secondary efficacy endpoints included, mean change in FEV1, pre-bronchodilator FVC, pre-dose morning and evening PEFR, symptom scores at 2, 4, 8, and 12 weeks. Patient preferences for device and safety were also assessed. At 12 weeks, the mean change in pre-dose morning PEFR in BAI and pMDI groups was 50.72 L/min and 48.82 L/min, respectively (p < 0.0001;...
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The fingertip is the most commonly injured part of the hand. When replantation of a fingertip amputation is not possible, flap reconstruction may be necessary for a functional and aesthetically pleasing outcome. This paper reviews... more
The fingertip is the most commonly injured part of the hand. When replantation of a fingertip amputation is not possible, flap reconstruction may be necessary for a functional and aesthetically pleasing outcome. This paper reviews commonly utilized reconstruction techniques with a focus on technical tricks and potential complications and how to avoid them, with illustrative cases.
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Systemic lupus erythematosus (SLE) patients have an increased risk of atherosclerosis. Identification of at-risk patients and the pathogenesis of atherosclerosis in SLE remain elusive. Paraoxonase 1 (PON1) and anti-apolipoprotein A-I... more
Systemic lupus erythematosus (SLE) patients have an increased risk of atherosclerosis. Identification of at-risk patients and the pathogenesis of atherosclerosis in SLE remain elusive. Paraoxonase 1 (PON1) and anti-apolipoprotein A-I antibody (anti-Apo A-I) appear to have a potential role in premature atherosclerosis in SLE. The aim of this work was to study PON1 activity and anti-Apo A-I antibody in SLE female patients and to demonstrate their relations to disease activity as well as disease related damage. Forty SLE female patients and 40 apparently healthy volunteers were included. Anti-Apo A-I antibodies levels and PON1 activity levels were assessed. Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and systemic Lupus International Collaboration Clinics (SLICC)/American College of Rheumatology (ACR) damage index were preformed in all patients. Compared with controls, SLE patients showed significantly lower PON1 activity and significantly higher titers of anti-Apo A-I....
Oxidative stress may play a pathogenic role in chronic hepatitis C (CHC). The present study examined the oxidative status in plasma of patients with CHC who received pegylated interferon and ribavirin therapy. The following groups were... more
Oxidative stress may play a pathogenic role in chronic hepatitis C (CHC). The present study examined the oxidative status in plasma of patients with CHC who received pegylated interferon and ribavirin therapy. The following groups were included: (1) sustained virological response (28 patients), (2) null response (26 patients), (3) breakthrough (24 patients), (4) relapse (24 patients), (5) spontaneous cure (23 patients) and (6) twenty five normal subjects as a control group. Markers of oxidative stress including plasma malondialdehyde, nitric oxide, reduced glutathione, total antioxidant capacity and uric acid as well as serum ALT, AST, alkaline phosphatase, total bilirubin, albumin, prothrombin time were studied. The study indicated significant decline in reduced glutathione and total antioxidant capacity and markedly elevated levels of malondialdehyde and nitric oxide in all groups compared with the controls. Null response group had the highest levels of malondialdehyde and nitric ...
Sickle cell anemia (SCA) is a chronic haemoglobinopathy that can affect many organs in the body including gastrointestinal tract. However, colonic involvement is very rare and usually in the form of ischemic colitis. We are reporting an... more
Sickle cell anemia (SCA) is a chronic haemoglobinopathy that can affect many organs in the body including gastrointestinal tract. However, colonic involvement is very rare and usually in the form of ischemic colitis. We are reporting an 11-year-old Saudi girl with SCA who presented with persistent diarrhea and was found to have inflammaftory bowel disease.
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... phthalimides Loren L. Braun*, Jing Xia and Mark J. Cooney Department of Chemistry, Idaho State University, Pocatello, Idaho 83209 Mohammed K. Ahmed and ... bromide, prepared from 0.73 g (30 mmoles) of magnesium and 4.8 g (30 mmoles)... more
... phthalimides Loren L. Braun*, Jing Xia and Mark J. Cooney Department of Chemistry, Idaho State University, Pocatello, Idaho 83209 Mohammed K. Ahmed and ... bromide, prepared from 0.73 g (30 mmoles) of magnesium and 4.8 g (30 mmoles) of bromobenzene was cool-ed in ...
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1 Department of Computer & Informatics, Maulana Azad National Urdu University, Gachi Bowli, Hyderabad, AP India E-mail :- mdmisbahuddin@yahoo.com ... 2 Department of Computer Science & Engineering, MGM'S College of... more
1 Department of Computer & Informatics, Maulana Azad National Urdu University, Gachi Bowli, Hyderabad, AP India E-mail :- mdmisbahuddin@yahoo.com ... 2 Department of Computer Science & Engineering, MGM'S College of Engineering, Nanded, Maharashtra India E-...
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Obstetrics and gynaecology always has reputation for being a highly litigious. The field of obstetrics and gynaecology is surrounded by different circumstances that stimulate the doctors to practice defensive medicine. This study was... more
Obstetrics and gynaecology always has reputation for being a highly litigious. The field of obstetrics and gynaecology is surrounded by different circumstances that stimulate the doctors to practice defensive medicine. This study was directed to assess the extent and the possible effect of defensive medicine phenomenon (in term of knowledge and prevalence) on medical decision making among different grades of obstetric and gynaecologic Sudanese doctors, and to determine any experience of medical litigations with respect to sources and factors associated with it (in term of area of work, characteristics of the area at which the doctors worked, professionalism, hospitals systems…ect). A total of 117 doctors were approached, their distribution according to job description was as follow: consultants (42.7 %, 50\117) registrars (34.2 %, 40\117) and specialists (23.1 %, 27\117). The majority 89.7 % had the impression that litigation against doctors are increasing and 27.6 % had a direct experience of litigation. In this study less than one half (42.7 %) of the surveyed doctors knew the concept of defensive medicine and 71.8 % reported practicing one or another form of defensive medicine. The different sources of the litigations reported by the doctors included: maternal death (n = 15), perinatal death (n = 5), other {misdiagnosis, intra-uterine fetal death, uterine perforation, rupture uterus} (n = 4), fetal distress (n = 3), injury to viscera (n = 3) and shoulder dystocia (n = 2). In this study the experience of medical litigation was significantly observed among those who worked in area of blame culture (90.6 % Vs 56.5 %, P = 0.000). In logistic regression model, there was no significant difference between those who knew the concept of defence medicine and those who didn&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;t. There should be strategic plan to reduce the practice of defensive medicine and medical litigation against doctors.
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Gastroduodenal obstruction is a common preterminal event for patients with gastric and pancreatic cancer who often undergo palliative surgical bypass. Endoscopic palliation with self-expanding metallic stents has emerged as a safe and an... more
Gastroduodenal obstruction is a common preterminal event for patients with gastric and pancreatic cancer who often undergo palliative surgical bypass. Endoscopic palliation with self-expanding metallic stents has emerged as a safe and an effective alternative to surgery, but experience with the technique remains limited. Twenty-eight patients hospitalized with GI obstruction because of incurable gastric or pancreatic cancer were recruited for a prospective study of palliation with self-expanding metallic stents. Complications and clinical outcomes were assessed. Stent insertion was technically successful in 26 patients. Thereafter, 24 patients resumed an adequate liquid or semisolid diet. Stent insertion facilitated hospital discharge for 20 patients. Occlusion of the stent because of tumor ingrowth occurred in 3 patients, but there was no complication related to stent insertion or the stent itself. Endoscopic placement of a self-expanding metallic stent is a simple, effective means of palliation for patients with malignant gastroduodenal obstruction.
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Algebraic geometry codes or Goppa codes are defined with places of degree one. In constructing generalised algebraic geometry codes places of higher degree are used. In this paper we present 41 new codes over GF(16) which improve on the... more
Algebraic geometry codes or Goppa codes are defined with places of degree one. In constructing generalised algebraic geometry codes places of higher degree are used. In this paper we present 41 new codes over GF(16) which improve on the best known codes of the same length and rate. The construction method uses places of small degree with a technique originally published over 10 years ago for the construction of generalised algebraic geometry codes.
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The Hamming weight enumerator function of the formally self-dual even, binary extended quadratic residue code of prime p = 8m + 1 is given by Gleason's theorem for singly-even code. Using this theorem, the Hamming weight distribution of... more
The Hamming weight enumerator function of the formally self-dual even, binary extended quadratic residue code of prime p = 8m + 1 is given by Gleason's theorem for singly-even code. Using this theorem, the Hamming weight distribution of the extended quadratic residue is completely determined once the number of codewords of Hamming weight j A_j, for 0 <= j <= 2m, are known. The smallest prime for which the Hamming weight distribution of the corresponding extended quadratic residue code is unknown is 137. It is shown in this paper that, for p=137 A_2m = A_34 may be obtained with out the need of exhaustive codeword enumeration. After the remainder of A_j required by Gleason's theorem are computed and independently verified using their congruences, the Hamming weight distributions of the binary augmented and extended quadratic residue codes of prime 137 are derived.
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Experimental and Numerical Studies on a Low Reynolds Number Airfoil for Wind Turbine Blades
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With use of the technique of competitive collisional quenching of two-photon dissociation, the collisional quenching of photoexcited bromobenzene ions was measured for 35 neutral partners. The number of collisions required for quenching... more
With use of the technique of competitive collisional quenching of two-photon dissociation, the collisional quenching of photoexcited bromobenzene ions was measured for 35 neutral partners. The number of collisions required for quenching ranged from 3.5 to 180, generally increasing with molecular complexity. For quench gases not containing unsaturation or heavy atoms (except HâO), the quenching efficiency gives an excellent plot
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... turbine applications Joji WATA, Mohammed FAIZAL, Boniface TALU, Lesia VANAWALU, Puamau SOTIA & M. Rafiuddin AHMED* ... Annu Rev Fluid Mech, 1983, 15: 223239 8 Henriques JCC, Marques da Silva F, Estanqueiro AI, et al. ...
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Bilateral breast cancer is uncommon (1-2.6% of all patients with breast carcinoma). There are conflicting reports and inadequate data regarding the incidence and survival of such patients. This study examined the frequency, mode of... more
Bilateral breast cancer is uncommon (1-2.6% of all patients with breast carcinoma). There are conflicting reports and inadequate data regarding the incidence and survival of such patients. This study examined the frequency, mode of detection, therapeutic modalities and histological features among the 2 breasts. Medical records of patients who were treated for breast cancer were reviewed at Khartoum Teaching Hospital, Sudan during a 5-year period of 1994 to 1999. Data of patients found to have bilateral breast cancer was analyzed focusing on the demographic information, family history, menstrual status, surgical therapy, chemoradiation, staging and histopathological characteristics. Of 521 patients treated for breast cancer, 90 (17.2%) were reported to have advanced breast carcinoma (stage III, IV) and 7 (1.3%) revealed bilateral cancer: 5 (0.9%) synchronous and 2 (0.4%) metachronous breast cancer. The median age was 47.3 years (range, 24-81 years). Four (57.1%) patients had positive family history for breast cancer. First breast cancer was detected by mammogram in 2 cases while second cancer was diagnosed by the same study in 5 patients. Five (71.5%) underwent mastectomy and 2(28.5%) were treated by lumpectomy and axillary dissection. Six patients presented with stage III and one with stage IV breast cancer. Invasive ductal carcinoma was reported to be the most common type found in 10 (71.5%) breasts. Grade III breast carcinoma was revealed in 9 and Grade I cancer in 3 specimens. Bilateral breast cancer is invariably advanced when diagnosed. Mammogram is a valuable tool in early detection. Whether synchronous or metachronous, both breasts often share the same histological type.
Research Interests: Tropical Medicine, Histology, Humans, Female, Incidence, and 4 moreAged, Middle Aged, Adult, and Retrospective Studies
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An algorithm of improving the performance of iter- ative decoding on perpendicular magnetic recording is presented. This algorithm follows on the authors' previous works on the parallel and serial concatenated turbo codes and... more
An algorithm of improving the performance of iter- ative decoding on perpendicular magnetic recording is presented. This algorithm follows on the authors' previous works on the parallel and serial concatenated turbo codes and low-density parity-check codes. The application of this algorithm with signal- to-noise ratio mismatch technique shows promising results in the presence of media noise. We also show that,
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ABSTRACT Accurate propagation models are required for predicting the propagation of electromagnetic waves within complex environments. This paper proposes the use of a new method to accurately compute the divergence and curl of... more
ABSTRACT Accurate propagation models are required for predicting the propagation of electromagnetic waves within complex environments. This paper proposes the use of a new method to accurately compute the divergence and curl of electromagnetic fields. The computation of the derivatives of vector fields is normally approximated using numerical methods such as the Finite-Dierence Time-Domain Method (FDTD), the Finite Integration Technique and the Multi-Resolution Time-Domain Method. These methods are all limited in terms of their accuracy, resolution, computational efficiency and numerical stability. This paper introduces a new method for computing derivatives based on Two-Dimensional (2D) Digital Signal Processing (DSP) techniques. The method involves computing a numerical approximation of the derivative of a function by considering the frequency domain definition of the derivative and designing a 2Dfinite impulse response (FIR) filter that implements the differentiation. Appropriate windowing functions are used to ensure that the FIR response is as close to the ideal 2D differentiator response as possible. This paper provides an example where the curl of a vectorfield is determined using this method and accuracy within a few percent is achieved. The proposed innovative method can be extended to three dimensions and used to find numerical solutions of Maxwells Equations, thus allowing it to be applied to the design of accurate propagation models.
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Bayes and frequentist estimators are obtained for the two-parameter Weibull failure time distribution with uncensored observations as well as the survival/reliability and hazard func-tions, which are used extensively in life testing and... more
Bayes and frequentist estimators are obtained for the two-parameter Weibull failure time distribution with uncensored observations as well as the survival/reliability and hazard func-tions, which are used extensively in life testing and survival analysis. The Bayes approach is obtained using Lindleys approximation technique with standard non-informative (vague) prior and a proposed generalisation of the non-informative prior. A simulation study is carried out to compare the performances of the methods. It is observed from the study that the unknown parameters, the reliability and hazard functions are best estimated by Bayes using linear ex-ponential loss with the proposed prior followed by general entropy loss function.
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It is shown that some well-known and some new cyclic codes with orthogonal parity-check equations can be constructed in the finite-field transform domain. It is also s hown that, for some binary linear cyclic codes, the performance of the... more
It is shown that some well-known and some new cyclic codes with orthogonal parity-check equations can be constructed in the finite-field transform domain. It is also s hown that, for some binary linear cyclic codes, the performance of the iterative decoder can be improved by substituting some of the dual code codewords in the parity-check matrix with other dual code
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A dual-corner-fed square patch is proposed to realize the dual-polarization operation. Its analysis results are compared with those of a dual-edge-fed patch. A new single-layer hybrid array of these elements has been designed, fabricated... more
A dual-corner-fed square patch is proposed to realize the dual-polarization operation. Its analysis results are compared with those of a dual-edge-fed patch. A new single-layer hybrid array of these elements has been designed, fabricated and measured, which is compact and low-cost. The measured isolation between two feeds is -23 dB at 12 GHz while its further improvement is expected