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Item Hypernatriuria and kaliuresis in enuretic children and the diurnal variation(Elsevier Inc., 1998) Vurgun N.; Yicrossed d Signitocrossed d Signlu M.R.; Ýpcan A.; Ari Z.; Tarhan S.; Balkan C.Purpose: We investigate the underlying pathophysiological cause of primary nocturnal enuresis by comparing electrolyte alterations in urine samples of enuretics during the daytime and nighttime compared with those of nonenuretic subjects. Materials and Methods: Urine output, urine specific gravity and urinary electrolytes in 15 enuretic and 12 nonenuretic children were measured. We collected daytime serum and urine samples of children fed a similar diet between 7 a.m. and 7 p.m., and nighttime between samples 7 p.m. and 7 a.m. Urinary calcium/creatinine ratio, tubular reabsorption of phosphorus and excretions of fractional sodium and potassium were calculated. Results: There was no significant difference between the calcium/creatinine ratio ratios. There was a significant increase in fractional sodium and fractional potassium values in enuretics compared to nonenuretics during the day and at night. Daytime and nighttime fractional sodium and fractional potassium values in enuretics were similar. In contrast to nonenuretics, enuretic patients had no diurnal variation of fractional sodium. There was significant positive correlation between bedwetting status, and fractional sodium and fractional potassium. Conclusions: Since sodium and potassium excretions were higher in enuretic patients than nonenuretic children, and no significant diurnal variation in urinary excretion of these ions there might be a difference in the mechanism of reabsorption of sodium and potassium between enuretic and nonenuretic children.Item The approximate solution of high-order linear Volterra-Fredholm integro-differential equations in terms of Taylor polynomials(Elsevier Inc., 2000) Yalçinbaş S.; Sezer M.In the present paper, a Taylor method is developed to find the approximate solution of high-order linear Volterra-Fredholm integro-differential equations under the mixed conditions in terms of Taylor polynomials about any point. In addition, examples that illustrate the pertinent features of the method are presented, and the results of study are discussed.Item Prevention of posterior capsule opacification by intraoperative single-dose pharmacologic agents(Elsevier Inc., 2001) Inan Ü.Ü.; Öztürk F.; Kaynak S.; Kurt E.; Emiroǧlu L.; Özer E.; Ilker S.S.; Güler C.Purpose: To determine whether an intraoperative single dose of dexamethasone, diclofenac, ethylenediaminetetraacetic acid (EDTA), a combination of EDTA and RGD peptide (arginine-glycin-aspartic acid sequence), or mitomycin-C (MMC) is a pharmacological means of preventing or reducing the development of posterior capsule opacification (PCO). Setting: Department of Ophthalmology, Celal Bayar University, School of Medicine, Manisa, and Department of Pathology, Dokur Eylül University, School of Medicine, izmir, Turkey. Methods: Fifty-four rabbits were randomly divided into 6 groups. Dexamethasone (4 mg/cc), diclofenac (2.5 mg/cc), EDTA (8 mg/cc), a combination of EDTA and RGD peptide (2.5 mg/cc), or MMC (0.04 mg/cc) was given, 0.1 cc by hydrodissection and 0.9 cc into the capsular bag after phacoemulsification. The sixth group served as a control group. After 3 months, the PCO was graded clinically and the proliferation of lens epithelial cells (LECs) was evaluated histologically. Results: The drugs were significantly effective in preventing PCO compared with the control (P < .005). Dexamethasone had a weaker effect than the other drugs. In histological analysis, although monolayer LECs in the dexamethasone and diclofenac groups were observed, there was no proliferative activity on the posterior capsules in the EDTA, EDTA+RGD, and MMC groups in contrast to the multilayer cells in the control. Conclusions: Intraoperative single-dose application of EDTA, EDTA+ RGD peptide combination, and MMC significantly prevented the development of PCO in rabbit eyes. Diclofenac was less effective but also reduced PCO. Although dexamethasone did not prevent the proliferation of LECs, it decreased PCO clinically. © 2001 ASCRS and ESCRS.Item The relationship between self-monitoring of blood glucose control and glycosylated haemoglobin in patients with type 2 diabetes with and without diabetic retinopathy(Elsevier Inc., 2003) Özmen B.; Boyvada S.Background: Diabetes mellitus (DM) is a major health problem with long-term microvascular and macrovascular complications responsible for the majority of its mortality and morbidity. The development and progression of diabetic complications are strongly related to the degree of glycemic control. To decrease the occurrence of these complications, instruments for self-monitoring of blood glucose (SMBG) have been developed and have become widely used among diabetic patients. In this study, we determined the relationship between SMBG control and glycosylated haemoglobin (HbAlc) levels in patients with type 2 diabetes, with and without diabetic retinopathy. Methods: Two hundred and sixty-seven type 2 diabetic patients (mean age [mean±S.D.]: 58.07±9.13 years, duration of diabetes: 8.63±6.8 years) participated in this study. Following an educational program on SMBG, glucometers and usage of oral antidiabetic agents or insulin, optic fundi were examined and HbAlc levels were measured at baseline and after 6 and 12 months. The patients were classified in three groups according to their funduscopic findings: without retinopathy (n=140, 52.4%), background retinopathy (n=75, 28.1%) and proliferative retinopathy (n=52, 19.5%). Results: HbAlc levels at baseline, after 6 and 12 months were 9.09±2.69%, 7.47±1.78% and 7.12±1.4%, respectively, mean±S.D. The values decreased significantly after the education program (P<.001 for both values compared with baseline). The prevalence of retinopathy (both background and proliferative) was 0.8% in the group of diabetics with a mean HbAlc level <6%, 7.1% in those between 6.1% and 6.9%; 9.4% in those between 7% and 7.9%; 11.8% between 8% and 8.9%; and 70.9% in those exceeding a mean HbAlc level of 9%. There was a statically significant relationship between proliferative diabetic retinopathy and body mass index (BMI; P<.001). The same relationship was observed between duration of diabetes and diabetic retinopathy (P<.001), but not between sex and diabetic retinopathy (P=.46). Conclusions: Implementing a program of SMBG control in type 2 diabetic patients results in lower levels of HbAlc at 6 and 12 months. In the group without diabetic retinopathy at 6- and 12-month controls, the mean HbAlc concentration is less than 7%, but in the group with diabetic (background and proliferative) retinopathy, this value could not be reduced below 7%. These results imply that SMBG would allow us to maintain better metabolic control by improving HbAlc levels and we have always kept in mind that SMBG was a part of an educational program. On the other hand, improving glycemic control prevents the onset or progression of diabetic microvascular complications, such as diabetic retinopathy, nephropathy and neuropathy. Long-term clinical studies should be performed to determine cost-effectiveness and the effects of SMBG on diabetic complications, morbidity and mortality. © 2003 Elsevier Science Inc. All rights reserved.Item Serum and urinary nitric oxide in Type 2 diabetes with or without microalbuminuria: Relation to glomerular hyperfiltration(Elsevier Inc., 2003) Apakkan Aksun S.; Özmen B.; Özmen D.; Parildar Z.; Şenol B.; Habif S.; Mutaf I.; Turgan N.; Bayindir O.Background: Glomerular hyperfiltration is considered as one of the pathophysiological mechanisms for the development of diabetic nephropathy. Oxidative stress is enhanced in patients with diabetes mellitus. Reportedly, nitric oxide (NO) might be involved in the pathogenesis of hyperfiltration. We investigated the relationship between hyperfiltration and NO system, and malondialdehyde (MDA) levels in Type 2 diabetics with/without microalbuminuria. Methods: In 39 microalbuminuric, 29 normoalbuminuric Type 2 diabetic patients and 32 healthy controls, serum creatinine, nitrite, nitrate, urinary microalbumin, nitrite, nitrate, plasma MDA and estimated glomerular filtration rate (EGFR) values, calculated according to the Cockcroft and Gault formula, were recorded. Results: Serum and urine NO levels were higher in both microalbuminurics and normoalbuminurics than controls. There were no significant differences in EGFR between groups. However, hyperfiltration was determined in 31% of normoalbuminurics and 20% of microalbuminurics. Serum and urine NO levels were higher in patients with hyperfiltration. Plasma MDA levels were significantly elevated in both microalbuminurics and normoalbuminurics when compared with controls. Serum glucose and microalbuminuria were positively correlated in microalbuminuric diabetics. Serum NO levels were also positively correlated with EGFR in both normoalbuminurics and microalbuminurics. HbA1c levels were positively correlated with both urinary albumin excretion and plasma MDA levels in normoalbuminuric diabetics. Conclusion: Hyperglycemia is associated with an increased NO biosynthesis and lipid peroxidation. Increased oxidative stress may contribute to the high NO levels in Type 2 diabetes. Furthermore, the high NO levels may lead to hyperfiltration and hyperperfusion, which in turn leads to an increase in urinary albumin excretion and thus causes progression of nephropathy in early Type 2 diabetes. © 2003 Elsevier Inc. All rights reserved.Item Valproate-associated reproductive and metabolic abnormalities: Are epileptic women at greater risk than bipolar women?(Elsevier Inc., 2003) Akdeniz F.; Taneli F.; Noyan A.; Yüncü Z.; Vahip S.Objective: Evidence indicates that valproate (VPA) may have an adverse impact on reproductive endocrine and metabolic functions in women with epilepsy. This study explores whether the association of VPA with reproductive endocrine abnormalities is applicable to women with bipolar disorder (BD) or is unique to women with epilepsy. Methods: Thirty female patients aged 18-40 years with a DSM-IV diagnosis of BD (15 on lithium monotherapy and 15 on VPA monotherapy or VPA in combination with lithium therapy) and 15 with idiopathic generalized epilepsy (IGE) on VPA monotherapy were evaluated for reproductive endocrine functioning and metabolic parameters. Results: The menarche age, mean length of menstrual cycle and mean length of menses were not significantly different between groups. None of the bipolar patients on lithium, three (20%) of the bipolar patients on VPA and seven (47%) of the epileptic patients on VPA reported menstrual disturbances. Hirsutism scores of the epilepsy group were significantly higher than those bipolar women, regardless of treatment. Serum total testosterone levels were significantly higher in patients (both with BD and with IGE) treated with VPA than in those treated with lithium. Serum FSH levels were significantly lower and LH-to-FSH ratio was significantly higher in patients with epilepsy than in patients with BD, regardless of treatment. The weight parameters and lipid values investigated did not differ significantly between the groups. Conclusion: The study supports the conclusion that VPA may be associated with menstrual abnormalities and increased total testosterone levels in both bipolar and epileptic patients although women with BD did not show clinical features of hyperandrogenism (menstrual abnormalities, hirsutism and truncal obesity) as did frequently as women with epilepsy. © 2002 Elsevier Science Inc. All rights reserved.Item The effect of chronic antidepressant treatment on serum brain-derived neurotrophic factor levels in depressed patients: A preliminary study(Elsevier Inc., 2005) Aydemir O.; Deveci A.; Taneli F.Recent studies suggested a role of brain-derived neurotrophic factor (BDNF) in depression. While BDNF levels are lower in depressed patients, antidepressant treatment increases serum BDNF levels of depressed patients. Our study aims to test the effect of chronic venlafaxine treatment on serum BDNF levels in patients with a major depressive disorder. Ten patients diagnosed as major depressive disorder according to DSM-IV are included in the study. Two of the patients had their first episode and were drug-naive, the other eight patients were drug-free for at least 4 weeks. The severity of depression was assessed with Hamilton Depression Rating Scale (HDRS). The control group consisted of ten age- and sex-matched subjects without any psychiatric disorder. Blood samples were collected at the baseline and after 12 weeks of antidepressant treatment (during remission). At the baseline the mean serum BDNF level was 17.9±9.1 ng/ml and the mean HDRS score was 23.2±4.6. Serum BDNF levels of the study group were significantly lower than in the control group (31.6±8.6 ng/ml). At the end of the study, the mean serum BDNF level was 34.6±7.1 ng/ml whereas the mean HDRS score was 8.2±3.9. From the baseline to the remission after 12 weeks of treatment, the increase in serum BDNF level and the decrease in HDRS score were statistically significant, respectively. When we compared the serum BDNF level of depressed patients at remission to that of the controls, there was no statistically significant difference. This study shows that venlafaxine treatment of depression improves serum BDNF level which may be considered as a nonspecific peripheral marker of depression. © 2004 Elsevier Inc. All rights reserved.Item The impact of co-morbid conditions on the SF-36: A primary-care-based study among hypertensives(Elsevier Inc., 2005) Aydemir O.; Ozdemir C.; Koroglu E.Background. Comorbidities in hypertension complicate the course causing more symptoms and deterioration in a patient's daily life. The aim of this present study is to describe the effect of comorbid conditions on health-related quality of life (HRQL) in hypertensive patients. Methods. The study was carried out in four different regions of Turkey by 156 general practitioners between October 1999 and April 2000. In addition to cardiological evaluation, SF-36 health survey questionnaire was used for quality of life measurement. Diagnosis of comorbid conditions were anamnesis based. Results. The mean age of the group (n = 938) was 58.1 ± 11.2, and 58.6% (n = 550) of the group was female. Total scores of the eight domains of SF-36 were lower than the normal population scores. Age and gender affected every domain of SF-36 scale negatively. Heart failure affected four of the domains, primarily physical domains. Previous transient ischemic attack was responsible for low HRQL in emotional role difficulties, vitality, and mental health, but previous stroke had an impact on physical functioning and emotional role. Previous myocardial infarction affected emotional role difficulties negatively whereas previous CABG surgery had a positive impact on the same domain. Obesity and angina pectoris affected physical functioning negatively, whereas peripheral arterial disease caused low general health perception. Nephropathy, retinopathy and diabetes had no impact on HRQL in hypertension. Conclusions. When the contribution of comorbid conditions is taken into consideration, it can be noticed that the impact of every other condition is similar to the same condition when it is pure. Hypertension per se seems to cause less impairment than expected in HRQL. © 2005 IMSS. Published by Elsevier Inc.Item The significance of venous dominance in color Doppler ultrasound for the diagnosis of primary nodular skin lesions: A new perspective in classification(Elsevier Inc., 2006) Özkol M.; Yoleri L.; Demir M.A.; Demireli P.; Pabuşçu Y.The aim of this study was to investigate the significance of color Doppler ultrasound (CDUS) findings in the differential diagnosis of suspicious nodular skin lesions and to compare the results according to the Giovagnorio 1999 classification and the modified classification. Forty nodular skin lesions were evaluated with CDUS and US. The number of arteries and veins was recorded in hypervascular lesions. Findings were compared with histopathological results. The specificity and predictivity of the modified classification were higher than those of the Giovagnorio 1999 classification. © 2006 Elsevier Inc. All rights reserved.Item Serum brain-derived neurotrophic factor level in dysthymia: A comparative study with major depressive disorder(Elsevier Inc., 2007) Aydemir Ö.; Deveci A.; Taskin O.E.; Taneli F.; Esen-Danaci A.In this present work, it is aimed to demonstrate BDNF serum concentrations in patients with dysthymia and to compare them with BDNF serum concentrations in patients with major depressive disorder and healthy subjects. The study was carried out in Celal Bayar University Hospital, Manisa, Turkey. Seventeen patients with dysthymia, 24 patients with major depressive disorder and 26 subjects without any psychiatric diagnosis and any psychiatric treatment were included in the study. The severity of depression was assessed with 17-item HAM-D. All subjects were asked to give their written consent. Blood samples were collected at baseline. Serum BDNF was kept at - 70 °C before testing, and assayed with an ELISA Kit (Promega; Madison, WI, USA), after dilution with the Block and Sample solution provided with the kit. The data were subjected to the analysis of variance. The BDNF serum concentrations of the dysthymia group (mean = 28.9 ± 9.2 ng/ml) were significantly higher than that of the major depressive disorder group (21.2 ± 11.3 ng/ml) (p = 0.002), and it was not different from the level of the control group (31.4 ± 8.8 ng/ml). BDNF serum concentrations and HAM-D score did not have any significant correlation in the dysthymia and major depression groups (r = - 0.276, p = 0.086). The low level of BDNF in patients with dysthymic disorder seems to point out that BDNF changes in mood disorders are state-dependent and vary according to the severity of depressive episodes. © 2007 Elsevier Inc. All rights reserved.Item Boron: Environmental Exposure and Human Health(Elsevier Inc., 2011) Korkmaz M.There is no evidence to prove that boron has any harmful effect on human health because of environmental pollution, although the usage of boron in environment is getting higher every day. Boron is not deposited in soft tissue, and the amount of boron in hard tissue is also very limited. In addition, most of the boron daily taken is excreted via urine. According to limited number of epidemiological studies, boron may have positive effect on human health if the intake dose is within 1-13 mg per day, as suggested by the World Health Organization. It is observed that the numbers of cancer and musculoskeletal diseases are very few for the people who are living in boron mining areas. Data from reproduction toxicology can be used to find daily boron intake, but negative findings obtained from animal experiments have not been proved by epidemiological studies. In addition, the clarifying role of the boron on cellular processes should not be overlooked in the risk assessment. Once there is enough information about boron, it is very easy to figure out reference daily boron intake. It is known that boron amount in drinking water can be kept under control and the amount of boron in foodstuffs is low; hence, boron exposure is not expected to have a negative impact on human health. © 2011 Elsevier B.V. All rights reserved.Item Analysis of Swarm Intelligence-Based Algorithms for Constrained Optimization(Elsevier Inc., 2013) Saka M.P.; Doǧan E.; Aydogdu I.Swarm intelligence refers to collective intelligence. Biologists and natural scientist have been studying the behavior of social insects due to their efficiency of solving complex problems such as finding the shortest path between their nest and food source or organizing their nests. In spite of the fact that these insects are unsophisticated individually, they make wonders as a swarm by interaction with each other and their environment. In last two decades, the behaviors of various swarms that are used in finding preys or mating are simulated into a numerical optimization technique. In this chapter, eight different swarm intelligence-based algorithms are summarized and their working steps are listed. These techniques are ant colony optimizer, particle swarm optimizer, artificial bee colony algorithm, glowworm algorithm, firefly algorithm, cuckoo search algorithm, bat algorithm, and hunting search algorithm. Two optimization problems taken from the literature are solved by all these eight algorithms and their performance are compared. It is noticed that most of the swarm intelligence-based algorithms are simple and robust techniques that determine the optimum solution of optimization problems efficiently without requiring much of a mathematical struggling. © 2013 Copyright © 2013 Elsevier Inc. All rights reserved.Item Some properties of limit inferior and limit superior for sequences of fuzzy real numbers(Elsevier Inc., 2014) Talo Ö.The limit inferior and limit superior of a bounded sequence of fuzzy real numbers have been introduced by Aytar et al. (2008) [1]. In this paper we give a simplified expressions for limit inferior and limit superior. The expressions is concise and convenient for use. As a straightforward corollary of this expressions, we can easily prove some properties of the limit inferior and limit superior. © 2014 Elsevier Inc. All rights reserved.Item Varenicline disrupts prepulse inhibition only in high-inhibitory rats(Elsevier Inc., 2014) Goktalay T.; Buyukuysal S.; Uslu G.; Coskun A.S.; Yorgancioglu A.; Kayir H.; Uzbay T.; Goktalay G.Varenicline, a widely used smoking cessation drug, has partial agonistic activity at α4β2 nicotinic receptors, and full agonistic activity at α7 nicotinic receptors. Thus it may interact with cognitive processes and may alleviate some of the cognitive disturbances observed in psychotic illnesses such as schizophrenia. We aimed to test the effects of varenicline on sensorimotor gating functioning, which is crucial for normal cognitive processes, especially for the integration of sensory and cognitive information processing and the execution of appropriate motor responses. Prepulse inhibition (PPI) of the acoustic startle reflex was used to test the sensorimotor gating functioning. First, the effects of varenicline and nicotine on rats having high or low baseline PPI levels were evaluated; then, varenicline was applied prior to apomorphine (0.5. mg/kg), and MK-801 (0.15. mg/kg), which are used as comparative models of PPI disruption. Varenicline (0.5-3. mg/kg) did not change PPI when given alone in naïve animals. When rats were selected according to their baseline PPI values, varenicline (1. mg/kg) significantly decreased PPI in high-inhibitory (HI) but not in low-inhibitory (LI) rats. Nicotine (1. mg/kg; tartrate salt) produced a similar activity in LI and HI groups. In combination experiments, varenicline did not reverse either apomorphine or the MK-801-induced disruption of PPI. These results demonstrate that the effects of both varenicline and nicotine on sensorimotor gating are influenced by the baseline PPI levels. Moreover, varenicline has no effect on apomorphine or the MK-801-induced disruption of PPI. © 2014 Elsevier Inc.Item The extension of the Knopp core theorem to the sequences of fuzzy numbers(Elsevier Inc., 2014) Talo Ö.; Çakan C.The concept of the core of a sequence of fuzzy numbers has been introduced by Aytar et al. in [The core of a sequence of fuzzy numbers, Fuzzy Sets and Systems, 159(24) (2008) 3369-3379]. Quite recently, some matrix transformations on the classical sets of sequences of fuzzy numbers have been characterized by Talo and Başar in [Determination of the duals of classical sets of sequences of fuzzy numbers and related matrix transformations, Comput. Math. Appl. 58 (2009) 717-733]. In this paper, we have proved a core theorem for sequences of fuzzy numbers which is analogous to the famous Knoop Core Theorem for real sequences. To achieve this goal, we have studied some properties of the lim sup and lim inf of sequences of fuzzy numbers. Also, we have characterized a class of positive regular matrices of fuzzy numbers such that these matrices leave the core of any bounded sequence of fuzzy numbers invariant. © 2013 Elsevier Inc. All rights reserved.Item Chronic actinic damage of facial skin(Elsevier Inc., 2014) Bilaç C.; Şahin M.T.; Öztürkcan S.Chronic actinic damage of the skin manifests itself as extrinsic skin aging (photoaging) and photocarcinogenesis. During the last decade, substantial progress has been made in understanding cellular and molecular mechanisms of photoaging. DNA photodamage and ultraviolet-generated reactive oxygen species are the initial events that lead to most of the typical histologic and clinical manifestations of chronic photodamage of the skin. Chronic actinic damage affects all layers of the skin. Keratinocytes, melanocytes, fibroblasts, and endothelial cells are altered by ultraviolet radiation and can result in numerous changes in human skin, particularly the skin of fair-skinned individuals. These changes include actinic keratosis, thickening and wrinkling, elastosis, telengiectasia, solar comedones, diffuse or mottled hyperpigmentation, and skin cancers. There are many options in the treatment of changes caused by chronic actinic damage. The most effective measure of prevention of the photoaging and photocarcinogenesis is sun protection. © 2014 Elsevier Inc.Item Hyperbaric oxygen treatment in the experimental spinal cord injury model(Elsevier Inc., 2014) Yaman O.; Yaman B.; Aydin F.; Var A.; Temiz C.Background context Spinal cord trauma is a major cause of mortality and morbidity. Although no known treatment for spinal cord injury exists, a limited number of effective treatment modalities and procedures are available that improve secondary injury. Hyperbaric oxygen (HBO) treatment has been used to assist in neurologic recovery after cranial injury or ischemic stroke. Purpose To report the findings on the effectiveness of HBO treatment on rats with experimental traumatic spinal cord injury. Improvement was evaluated through motor strength assessment and nitrite level assay testing. Study design We randomly distributed 40 rats among 5 groups of 8 rats each: sham incurable trauma, induced trauma, HBO treatment begun at the 1st hour, HBO treatment begun at the 6th hour, and HBO treatment begun at the 24th hour. Method The HBO treatment was administered to rats in three of the groups and conducted in two 90-minute sessions, under an absolute atmospheric pressure of 2.4 at 100% oxygen for 5 days. In the motor strength evaluations, all the rats were observed during the inclined plane test and clinical motor examination on the first, third, and fifth days. In addition, the nitrite levels of spinal cord tissues on the sixth day were also studied. Results Results from the inclined plane levels and motor strength test from all the three groups undergoing HBO treatment were higher than those from Group 2. It was also determined that early HBO treatment resulted in higher recovery rates (groups 3 and 4). The highest levels were seen in the group in which the HBO treatments were started in the first hour (Group 3). It was noted that nitrite levels of rats in the group exposed to trauma increased, compared with the sham group, but increased levels also diminished after HBO treatments. Again, the greatest decrease in nitrite levels was evident in the group where the HBO treatment was started the earliest (Group 3). Conclusions Prompt HBO treatment after trauma significantly contributed to the clinical, histopathologic, and biochemical recovery of the rats. © 2014 Elsevier Inc. All rights reserved.Item Solution of the delayed single degree of freedom system equation by exponential matrix method(Elsevier Inc., 2014) Çevik M.; Mustafa Bahşi M.; Sezer M.In this paper, an exponential collocation method for the solution linear delay differential equations with constant delay is presented. The utility of this matrix based method is that it is very systematic and by writing a Maple program, any type of second order linear differential delay equation can be solved easily. The method is applied to three different types of delay equations; linear oscillator with delay (i) in the restoring force term, (ii) in the damping term, and (iii) in the acceleration term. Time response curves have been plotted for each type and the effect of the parameters of the delay terms has been shown. An error analysis based on residual function is carried out to show the accuracy of the results. © 2014 Elsevier Inc. All rights reserved.Item Laguerre polynomial approach for solving Lane-Emden type functional differential equations(Elsevier Inc., 2014) Gürbüz B.; Sezer M.In this paper, a numerical method, which is called the Laguerre collocation method, for the approximate solution of Lane-Emden type functional differential equations in terms of Laguerre polynomials are derived. The method is based on the matrix relations of Laguerre polynomials and their derivatives, and reduces the solution of the Lane-Emden type functional differential equation to the solution of a matrix equation corresponding to system of algebraic equations with the unknown Laguerre coefficients. Also, some illustrative examples are included to demonstrate the validity and applicability of the proposed method. © 2014 Elsevier Inc. All rights reserved.Item Taylor collocation approach for delayed Lotka-Volterra predator-prey system(Elsevier Inc., 2015) Gokmen E.; Isik O.R.; Sezer M.In this study, a numerical approach is proposed to obtain approximate solutions of the system of nonlinear delay differential equations defining Lotka-Volterra prey-predator model. By using the Taylor polynomials and collocation points, this method transforms the population model into a matrix equation. The matrix equation corresponds to a system of nonlinear equations with the unknown Taylor coefficients. Numerical examples are also given to demonstrate the validity and applicability of the presented technique. The method is easy to implement and produces accurate results. All numerical computations have been performed on the computer algebraic system Maple 15. © 2015 Elsevier Inc. All rights reserved.