Cengiz Sen - Academia.edu (original) (raw)
Papers by Cengiz Sen
Ankle and hindfoot deformities in 11 patients with a mean age of 15 (range, four to 35) have been... more Ankle and hindfoot deformities in 11 patients with a mean age of 15 (range, four to 35) have been gradually corrected by an llizarov external fixator. In all patients, supramalleolar osteotomy was utilized by percutaneous drilling and osteotomy technique. The patients were evaluated clinically by the AOFAS scoring system and radiologically by malorientation and malalignment tests described by Paley. The purpose of the current study is to evaluate the efficacy of supramalleolar osteotomy and correction by an Ilizarov device in treating hindfoot and ankle deformities. The mean external fixation period was five (2.5 to eight) months. The mean interval between the operation and last follow-up examination was 19 (13 to 26) months. The patients improved an average of 30 points after the operation regarding to AOFAS score. A plantigrade foot was achieved in the whole group. Radiologically, no malalignment or malorientation was measured. Equal leg lengths were achieved in all nine patients with one exception. Complications were graded after Paley as minor problems in 11 patients and as obstacles requiring surgical interventions in four patients. Sequelae remained in only one patient. Ankle and hindfoot deformities caused by various etiologies are complicated by poor soft tissue condition and a short foot. A supramalleolar osteotomy and Ilizarov external fixator can safely and effectively correct these deformities.
Acta orthopaedica et traumatologica turcica, 2015
Three methods of surgery used in the treatment of knee osteoarthritis (OA) are mobile bearing uni... more Three methods of surgery used in the treatment of knee osteoarthritis (OA) are mobile bearing unicompartmental knee arthroplasty (Oxford UKA), opening wedge high tibial osteotomy (HTO), and dome-type HTO. This article aimed to retrospectively compare these three methods in terms of outcomes for health status, patient satisfaction, and function. Between 2003 and 2010, 255 knees of 235 patients underwent operations for medial knee OA. Three types of surgery were performed. Group 1 consisted of 109 knees of 94 patients who underwent Oxford UKA. Group 2 was made up of 36 knees of 36 patients who underwent HTO using circular external fixation, and Group 3 comprised 57 knees of 52 patients on whom opening wedge type HTO using locking plate fixation was performed. SF-36 and HSS knee scores were used to compare the functional outcomes among groups. Statistically significant differences were found between the preoperative and postoperative measures in all 3 of the treatment groups for physic...
We evaluated the short-term results of opening focal dome osteotomy in the treatment of varus gon... more We evaluated the short-term results of opening focal dome osteotomy in the treatment of varus gonarthrosis associated with medial laxity. Seventeen knees of 16 patients with varus gonarthrosis associated with medial laxity (15 females, 1 male; mean age 51.6 years; range 45 to 58 years) were managed with opening focal dome osteotomy in our clinic between September 2003 and July 2006. The patients were evaluated for alignment of the lower extremities and medial laxity before and after the operation and were also evaluated clinically by Knee Society (KS) knee scores and Hospital for Special Surgery (HSS) knee scores. Mean follow-up was 27 months (range 12 to 44 months). Postoperatively, an average 13.8+/-3.3 degrees mechanical femuro-tibial angle (mFTA) correction was achieved (p=0.001). Average preoperative mechanical varus was 9.9+/-3.1 degrees whereas the mean postoperative mechanical valgus was 3.9+/-0.8 degrees (p=0.001). An average 2.6+/-1.2 mm reduction in medial laxity was ensu...
Acta orthopaedica et traumatologica turcica, 2014
The aim of this study was to compare the biomechanical properties of minimal invasive sliding ant... more The aim of this study was to compare the biomechanical properties of minimal invasive sliding antirotator compressive hip screw (MIS-A-CHS), and multiple cannulated screws (CS) on a Pauwels type 3 femoral neck fracture model. A Pauwels type 3 vertical femoral neck fractures was created on 12 third-generation proximal femur models which were divided into two equal groups. The fracture was fixed with three CS in the first group, and MIS-A-CHS in the second group. The axial and rotational stiffness and maximum compression effect were compared between the groups. The axial and rotational stiffness and maximum compression were significantly higher in MIS-A-CHS group (912.5 N, 540 N and 10.2 N/m, respectively) than the CS group (627.5 N, 380 N, and 3.9 N/m, respectively). MIS-A-CHS appears to be a more secure fixation method in Pauwels type 3 femoral neck fractures than the CS.
International orthopaedics, 2003
In hips with acetabular dysplasia, we performed Kotz osteotomy (group 1) in 22 hips (20 patients;... more In hips with acetabular dysplasia, we performed Kotz osteotomy (group 1) in 22 hips (20 patients; mean age 24.3 years) and Ganz osteotomy (group 2) in 23 hips (22 patients; mean age 23.1 years). Group 1 was followed 83.3 (56-112) months and group 2 40.9 (24-66) months. In group 1, Harris hip score improved from average 74.9 to 86.9, mean center edge (CE) angle from -4.5 degrees to 30.3 degrees, and mean vertical center edge (VCE) angle from 5.3 degrees to 36.2 degrees. In group 2, Harris hip score improved from average 76.6 to 91.1, mean CE angle from -5.9 degrees to 32.0 degrees, and mean VCE angle from 5.0 degrees to 41.3 degrees. Using Pauwels criteria, regression was observed in 12 hips in group 1 and one progressed. In group 2, 15 hips showed regression and three progressed. In patients treated with Ganz osteotomy, the complication rate was higher and the complications more serious than in patients treated with Kotz osteotomy. Most complications were, however, seen among the fi...
Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA, 2003
We evaluated the midterm results of high tibial osteotomy in patients with medial compartment art... more We evaluated the midterm results of high tibial osteotomy in patients with medial compartment arthritis. This study included 53 patients treated with high tibial osteotomy accompanied by either internal fixation (group A, n=26) or Ilizarov-type external fixator (group B, n=27). Clinical assessment of patients was performed using Hospital of Special Surgery scoring. Radiography was based on orientation angles of the knee (medial proximal tibial angle, lateral distal femoral angle, posterior proximal tibial angle) and mechanic axis alignment test. We used the Insall-Salvati index to determine patellar height. The mean follow-up in group A was 77 months (range 63-118) and that in group B 72 months (range 61-113). The patients of group B demonstrated better results in terms of Hospital of Special Surgery score, alignment of lower extremity, and preventing of progression of arthritis. We believe that normal alignment and orientation of the knee could be precisely established with a circu...
Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA, 2003
We evaluated the results of arthroscopic meniscectomy in patients with discoid lateral menisci of... more We evaluated the results of arthroscopic meniscectomy in patients with discoid lateral menisci of the knee. Discoid lateral menisci were detected in 308 patients, of whom 197 (124 males, 73 females; mean age 34.5 years, range 6-67) were clinically, radiologically, and arthroscopically found to be symptomatic and underwent partial meniscectomy. The average period between injury and operation was 13.2 months (range 6-52). The results were evaluated according to the Ikeuchi and Lysholm criteria. The mean follow-up was 57.8 months (range 24-138). The most common complaints were pain (66%) and joint line tenderness (61%). Widening of lateral joint space was the most common radiological finding (25%). The confirmation of diagnosis by magnetic resonance imaging was not congruent with arthroscopic results for some patients (31%). According to the Ikeuchi criteria, the results were excellent in 110 patients (56%), good in 53 (27%), fair in 26 (13%), and poor in 8 (4%). On the other hand, acc...
Archives of orthopaedic and trauma surgery, 2002
In this study we evaluated the interim results of surgical management of intraarticular calcaneal... more In this study we evaluated the interim results of surgical management of intraarticular calcaneal fractures in 26 feet in 19 patients. The mean age of the 15 male and 4 female patients in our series was 28.3 (range 17-54) years. There were 7 bilateral and 12 unilateral fractures. We obtained anteroposterior (AP), lateral, and skyline views and computed tomography (CT) scans of all patients preoperatively. According to Sanders CT classification, we detected type II, III, and IV fractures in 12, 10, and 4 cases, respectively. We performed extended lateral incisions in all patients but one and used Sherman plate, screw, and staples to achieve anatomic reduction. The mean follow-up period was 38.2 (range 18-50) months. Patients were evaluated by X-ray, CT, and Maryland foot score. We found that anatomic reduction had been achieved in 20 cases as confirmed by X-ray and CT postoperatively. With regard to the Maryland foot score, excellent, good, fair, and poor results were obtained in 9, ...
The two eg-orbital model, including Jahn-Teller lattice distortions and the superexchange interac... more The two eg-orbital model, including Jahn-Teller lattice distortions and the superexchange interaction, is studied using unbiased exact diagonalization Monte Carlo techniques at a doping value x=0.25. A canonical colossal magnetoresistance (CMR) resistivity vs. temperature shape is obtained with a resistivity peak of nearly two orders of magnitude. We investigate the Monte Carlo evolution and temperature dependence of the spin, lattice,
Cartilage, 2011
Tissue repair that occurs after microfracture does not include hyaline-like cartilage. Therefore,... more Tissue repair that occurs after microfracture does not include hyaline-like cartilage. Therefore, other treatment modalities must be combined with microfracture to improve repair tissue quality. In this study, we combined exogenous hyaluronic acid with microfracture. Thirty mature New Zealand rabbits were randomly divided into 3 groups as control, microfracture (MF), and microfracture and hyaluronic acid (MFHA). Four-millimetre full-thickness cartilage defects were created in the medial femoral condyle of each rabbit. Microfracture was performed on defects in the MF and MFHA groups. At 1 week following surgery, 1 mL of saline was injected into the knees of the control and MF groups, whereas 1 mL (15 mg/mL) hyaluronic acid was injected into the knees of the MFHA group 3 times weekly. At 6 months postsurgery, defects were evaluated according to the ICRS (International Cartilage Repair Society) and Wakitani scales. According to the ICRS and Wakitani scales, the quality of repair tissue was improved in MF and MFHA groups as compared the control group (P = 0.001 and 0.001, respectively). No significant difference was observed between the MF and MFHA groups (P = 0.342). According to the model in this study, no beneficial effect was obtained when HA injection was combined with microfracture in the treatment of full-thickness cartilage defects.
Journal of Physics-condensed Matter, 2008
This paper is a brief review of the status of 'phase separation' ideas in manganites and ... more This paper is a brief review of the status of 'phase separation' ideas in manganites and cuprates, mainly focused on the recent efforts by the authors. It is argued that in the last year considerable progress has been made in the understanding of manganites, since the famous colossal magnetoresistance peak in the resistivity versus temperature has been numerically observed in
SpringerPlus, 2014
The aim of this experimental animal model study is to investigate the effects of caffeic acid phe... more The aim of this experimental animal model study is to investigate the effects of caffeic acid phenethyl ester (CAPE) and melatonin on the maturation of newly-formed regenerated bone in distraction osteogenesis. Unilateral femoral lengthening(extension) was applied to 39 adult male Wistar albino rats, which were randomly allocated to 3 groups of 13; control, melatonin and CAPE groups. Through a 7-day latent waiting period and 15 days of distraction, melatonin of 25 mg/kg and CAPE of 10 μmol/kg were administered to the respective groups. The animals were sacrificed on Day 82. Radiographic, histological and biomechanical evaluations were made and measurements were taken. At the end of 82 days, the distraction osteogenesis area was seen to be completely filled with new bone formation in all 3 groups both radiologically and histologically. Biomechanically, the maximum torsional fracture strength (Maximum Torque (N-m)) of the melatonin group was higher compared to that of the control group, although it was not statistically significant (p > 0.05). The maximum torsional momentum of the CAPE group was statistically significantly high (p < 0.05). The degree of rigidity (N-m/deg) of both the melatonin and CAPE groups was higher than that of the control group and the CAPE group was found to be statistically significantly higher than the melatonin group (p < 0.05). Melatonin and CAPE increase the maturation of new bone in distraction osteogenesis. These effects are probably due to the reducing effect on bone resorption by inhibiting NF-κB and free oxygen radicals.
Physical Review B, 2006
The one-and two-orbital double-exchange models for manganites are studied using Monte Carlo compu... more The one-and two-orbital double-exchange models for manganites are studied using Monte Carlo computational techniques in the presence of a robust electron-phonon coupling ͑but neglecting the antiferromagnetic exchange J AF between the localized spins͒. The focus in this effort is on the analysis of charge transport. Our results for the one-orbital case confirm and extend previous recent investigations that showed the presence of robust peaks in the resistivity versus temperature curves for this model. Quenched disorder substantially enhances the magnitude of the effect, while magnetic fields drastically reduce the resistivity. A simple picture for the origin of these results is presented. It is also shown that even for the case of just one electron, the resistance curves present metallic and insulating regions by varying the temperature, as it occurs at finite electronic density. Moreover, in the present study these investigations are extended to the more realistic two-orbital model for manganites. The transport results for this model show large peaks in the resistivity versus temperature curves, located at approximately the Curie temperature, and with associated large magnetoresistance factors. Overall, the magnitude and shape of the effects discussed here resemble experiments for materials such as La 0.70 Ca 0.30 MnO 3 , and they are in agreement with the current predominant theoretical view that competition between a metal and an insulator, enhanced by quenched disorder, is crucial to understanding the colossal magnetoresistance ͑CMR͒ phenomenon. However, it is argued that further work is still needed to fully grasp the experimentally observed CMR effect, since in several other Mn oxides an antiferromagnetic chargeordered orbital-ordered state is the actual competitor of the ferromagnetic metal.
Physics Procedia, 2010
We investigate the one-orbital model for manganites with cooperative phonons and superexchange co... more We investigate the one-orbital model for manganites with cooperative phonons and superexchange coupling J AF via large-scale Monte Carlo (MC) simulations. Results for two-orbitals are also briefly discussed. Focusing on an the realistic electronic density n = 0.75, a regime of competition between ferromagnetic (FM) metallic and charge-ordered (CO) insulating states was identified in the finite temperature phase diagram. In the vicinity of the associated bicritical point, colossal magnetoresistance (CMR) effects were observed. The CMR magnitude is much larger than recently reported when randomly distributed polarons form the competing insulator. The appearance of CMR is associated with the development of short-distance correlations among polarons, above the spin ordering temperatures, resembling the charge arrangement of the low-temperature CO state. We present calculations of charge-charge correlations as well as typical Monte Carlo snapshots to support this view. Cengiz Şen et al. / Physics Procedia 00 (2010) 1-13 2
Physical Review Letters, 2005
Tennessee 37996 and Condensed Matter Sciences Division, Oak Ridge National Lab, TN 37381, USA
Physical Review B, 2006
Considerable progress has been recently made in the theoretical understanding of the colossal mag... more Considerable progress has been recently made in the theoretical understanding of the colossal magnetoresistance (CMR) effect in manganites. The existence of inhomogeneous states has been shown to be directly related with this phenomenon, both in theoretical studies and experimental investigations. The analysis of simple models with two competing states and a resistor network approximation to calculate conductances has confirmed that
We present a non-perturbative multi-scale extension to the Dynamical Cluster Approximation (DCA) ... more We present a non-perturbative multi-scale extension to the Dynamical Cluster Approximation (DCA) based on the two particle irreducible vertex gamma. The correlations at short length scales are calculated exactly using Quantum Monte Carlo (QMC) on small cluster of size Nc^(1), and long length scales are treated at the dynamical mean field level. Intermediate length scales are treated on a second cluster of size Nc^(2)> Nc^(1) by approximating its two-particle irreducible vertex with that of the smaller cluster, which is calculated by retaining its full momentum and frequency dependence. The resulting self energy of the large cluster is calculated using the Schwinger-Dyson equation. The method is applied to the 2D Hubbard model with cluster sizes Nc^(2)>=Nc^(1) and the results are compared with those that are calculated using QMC by increasing the size of the small cluster Nc^(1) up to Nc^(2).
Ankle and hindfoot deformities in 11 patients with a mean age of 15 (range, four to 35) have been... more Ankle and hindfoot deformities in 11 patients with a mean age of 15 (range, four to 35) have been gradually corrected by an llizarov external fixator. In all patients, supramalleolar osteotomy was utilized by percutaneous drilling and osteotomy technique. The patients were evaluated clinically by the AOFAS scoring system and radiologically by malorientation and malalignment tests described by Paley. The purpose of the current study is to evaluate the efficacy of supramalleolar osteotomy and correction by an Ilizarov device in treating hindfoot and ankle deformities. The mean external fixation period was five (2.5 to eight) months. The mean interval between the operation and last follow-up examination was 19 (13 to 26) months. The patients improved an average of 30 points after the operation regarding to AOFAS score. A plantigrade foot was achieved in the whole group. Radiologically, no malalignment or malorientation was measured. Equal leg lengths were achieved in all nine patients with one exception. Complications were graded after Paley as minor problems in 11 patients and as obstacles requiring surgical interventions in four patients. Sequelae remained in only one patient. Ankle and hindfoot deformities caused by various etiologies are complicated by poor soft tissue condition and a short foot. A supramalleolar osteotomy and Ilizarov external fixator can safely and effectively correct these deformities.
Acta orthopaedica et traumatologica turcica, 2015
Three methods of surgery used in the treatment of knee osteoarthritis (OA) are mobile bearing uni... more Three methods of surgery used in the treatment of knee osteoarthritis (OA) are mobile bearing unicompartmental knee arthroplasty (Oxford UKA), opening wedge high tibial osteotomy (HTO), and dome-type HTO. This article aimed to retrospectively compare these three methods in terms of outcomes for health status, patient satisfaction, and function. Between 2003 and 2010, 255 knees of 235 patients underwent operations for medial knee OA. Three types of surgery were performed. Group 1 consisted of 109 knees of 94 patients who underwent Oxford UKA. Group 2 was made up of 36 knees of 36 patients who underwent HTO using circular external fixation, and Group 3 comprised 57 knees of 52 patients on whom opening wedge type HTO using locking plate fixation was performed. SF-36 and HSS knee scores were used to compare the functional outcomes among groups. Statistically significant differences were found between the preoperative and postoperative measures in all 3 of the treatment groups for physic...
We evaluated the short-term results of opening focal dome osteotomy in the treatment of varus gon... more We evaluated the short-term results of opening focal dome osteotomy in the treatment of varus gonarthrosis associated with medial laxity. Seventeen knees of 16 patients with varus gonarthrosis associated with medial laxity (15 females, 1 male; mean age 51.6 years; range 45 to 58 years) were managed with opening focal dome osteotomy in our clinic between September 2003 and July 2006. The patients were evaluated for alignment of the lower extremities and medial laxity before and after the operation and were also evaluated clinically by Knee Society (KS) knee scores and Hospital for Special Surgery (HSS) knee scores. Mean follow-up was 27 months (range 12 to 44 months). Postoperatively, an average 13.8+/-3.3 degrees mechanical femuro-tibial angle (mFTA) correction was achieved (p=0.001). Average preoperative mechanical varus was 9.9+/-3.1 degrees whereas the mean postoperative mechanical valgus was 3.9+/-0.8 degrees (p=0.001). An average 2.6+/-1.2 mm reduction in medial laxity was ensu...
Acta orthopaedica et traumatologica turcica, 2014
The aim of this study was to compare the biomechanical properties of minimal invasive sliding ant... more The aim of this study was to compare the biomechanical properties of minimal invasive sliding antirotator compressive hip screw (MIS-A-CHS), and multiple cannulated screws (CS) on a Pauwels type 3 femoral neck fracture model. A Pauwels type 3 vertical femoral neck fractures was created on 12 third-generation proximal femur models which were divided into two equal groups. The fracture was fixed with three CS in the first group, and MIS-A-CHS in the second group. The axial and rotational stiffness and maximum compression effect were compared between the groups. The axial and rotational stiffness and maximum compression were significantly higher in MIS-A-CHS group (912.5 N, 540 N and 10.2 N/m, respectively) than the CS group (627.5 N, 380 N, and 3.9 N/m, respectively). MIS-A-CHS appears to be a more secure fixation method in Pauwels type 3 femoral neck fractures than the CS.
International orthopaedics, 2003
In hips with acetabular dysplasia, we performed Kotz osteotomy (group 1) in 22 hips (20 patients;... more In hips with acetabular dysplasia, we performed Kotz osteotomy (group 1) in 22 hips (20 patients; mean age 24.3 years) and Ganz osteotomy (group 2) in 23 hips (22 patients; mean age 23.1 years). Group 1 was followed 83.3 (56-112) months and group 2 40.9 (24-66) months. In group 1, Harris hip score improved from average 74.9 to 86.9, mean center edge (CE) angle from -4.5 degrees to 30.3 degrees, and mean vertical center edge (VCE) angle from 5.3 degrees to 36.2 degrees. In group 2, Harris hip score improved from average 76.6 to 91.1, mean CE angle from -5.9 degrees to 32.0 degrees, and mean VCE angle from 5.0 degrees to 41.3 degrees. Using Pauwels criteria, regression was observed in 12 hips in group 1 and one progressed. In group 2, 15 hips showed regression and three progressed. In patients treated with Ganz osteotomy, the complication rate was higher and the complications more serious than in patients treated with Kotz osteotomy. Most complications were, however, seen among the fi...
Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA, 2003
We evaluated the midterm results of high tibial osteotomy in patients with medial compartment art... more We evaluated the midterm results of high tibial osteotomy in patients with medial compartment arthritis. This study included 53 patients treated with high tibial osteotomy accompanied by either internal fixation (group A, n=26) or Ilizarov-type external fixator (group B, n=27). Clinical assessment of patients was performed using Hospital of Special Surgery scoring. Radiography was based on orientation angles of the knee (medial proximal tibial angle, lateral distal femoral angle, posterior proximal tibial angle) and mechanic axis alignment test. We used the Insall-Salvati index to determine patellar height. The mean follow-up in group A was 77 months (range 63-118) and that in group B 72 months (range 61-113). The patients of group B demonstrated better results in terms of Hospital of Special Surgery score, alignment of lower extremity, and preventing of progression of arthritis. We believe that normal alignment and orientation of the knee could be precisely established with a circu...
Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA, 2003
We evaluated the results of arthroscopic meniscectomy in patients with discoid lateral menisci of... more We evaluated the results of arthroscopic meniscectomy in patients with discoid lateral menisci of the knee. Discoid lateral menisci were detected in 308 patients, of whom 197 (124 males, 73 females; mean age 34.5 years, range 6-67) were clinically, radiologically, and arthroscopically found to be symptomatic and underwent partial meniscectomy. The average period between injury and operation was 13.2 months (range 6-52). The results were evaluated according to the Ikeuchi and Lysholm criteria. The mean follow-up was 57.8 months (range 24-138). The most common complaints were pain (66%) and joint line tenderness (61%). Widening of lateral joint space was the most common radiological finding (25%). The confirmation of diagnosis by magnetic resonance imaging was not congruent with arthroscopic results for some patients (31%). According to the Ikeuchi criteria, the results were excellent in 110 patients (56%), good in 53 (27%), fair in 26 (13%), and poor in 8 (4%). On the other hand, acc...
Archives of orthopaedic and trauma surgery, 2002
In this study we evaluated the interim results of surgical management of intraarticular calcaneal... more In this study we evaluated the interim results of surgical management of intraarticular calcaneal fractures in 26 feet in 19 patients. The mean age of the 15 male and 4 female patients in our series was 28.3 (range 17-54) years. There were 7 bilateral and 12 unilateral fractures. We obtained anteroposterior (AP), lateral, and skyline views and computed tomography (CT) scans of all patients preoperatively. According to Sanders CT classification, we detected type II, III, and IV fractures in 12, 10, and 4 cases, respectively. We performed extended lateral incisions in all patients but one and used Sherman plate, screw, and staples to achieve anatomic reduction. The mean follow-up period was 38.2 (range 18-50) months. Patients were evaluated by X-ray, CT, and Maryland foot score. We found that anatomic reduction had been achieved in 20 cases as confirmed by X-ray and CT postoperatively. With regard to the Maryland foot score, excellent, good, fair, and poor results were obtained in 9, ...
The two eg-orbital model, including Jahn-Teller lattice distortions and the superexchange interac... more The two eg-orbital model, including Jahn-Teller lattice distortions and the superexchange interaction, is studied using unbiased exact diagonalization Monte Carlo techniques at a doping value x=0.25. A canonical colossal magnetoresistance (CMR) resistivity vs. temperature shape is obtained with a resistivity peak of nearly two orders of magnitude. We investigate the Monte Carlo evolution and temperature dependence of the spin, lattice,
Cartilage, 2011
Tissue repair that occurs after microfracture does not include hyaline-like cartilage. Therefore,... more Tissue repair that occurs after microfracture does not include hyaline-like cartilage. Therefore, other treatment modalities must be combined with microfracture to improve repair tissue quality. In this study, we combined exogenous hyaluronic acid with microfracture. Thirty mature New Zealand rabbits were randomly divided into 3 groups as control, microfracture (MF), and microfracture and hyaluronic acid (MFHA). Four-millimetre full-thickness cartilage defects were created in the medial femoral condyle of each rabbit. Microfracture was performed on defects in the MF and MFHA groups. At 1 week following surgery, 1 mL of saline was injected into the knees of the control and MF groups, whereas 1 mL (15 mg/mL) hyaluronic acid was injected into the knees of the MFHA group 3 times weekly. At 6 months postsurgery, defects were evaluated according to the ICRS (International Cartilage Repair Society) and Wakitani scales. According to the ICRS and Wakitani scales, the quality of repair tissue was improved in MF and MFHA groups as compared the control group (P = 0.001 and 0.001, respectively). No significant difference was observed between the MF and MFHA groups (P = 0.342). According to the model in this study, no beneficial effect was obtained when HA injection was combined with microfracture in the treatment of full-thickness cartilage defects.
Journal of Physics-condensed Matter, 2008
This paper is a brief review of the status of 'phase separation' ideas in manganites and ... more This paper is a brief review of the status of 'phase separation' ideas in manganites and cuprates, mainly focused on the recent efforts by the authors. It is argued that in the last year considerable progress has been made in the understanding of manganites, since the famous colossal magnetoresistance peak in the resistivity versus temperature has been numerically observed in
SpringerPlus, 2014
The aim of this experimental animal model study is to investigate the effects of caffeic acid phe... more The aim of this experimental animal model study is to investigate the effects of caffeic acid phenethyl ester (CAPE) and melatonin on the maturation of newly-formed regenerated bone in distraction osteogenesis. Unilateral femoral lengthening(extension) was applied to 39 adult male Wistar albino rats, which were randomly allocated to 3 groups of 13; control, melatonin and CAPE groups. Through a 7-day latent waiting period and 15 days of distraction, melatonin of 25 mg/kg and CAPE of 10 μmol/kg were administered to the respective groups. The animals were sacrificed on Day 82. Radiographic, histological and biomechanical evaluations were made and measurements were taken. At the end of 82 days, the distraction osteogenesis area was seen to be completely filled with new bone formation in all 3 groups both radiologically and histologically. Biomechanically, the maximum torsional fracture strength (Maximum Torque (N-m)) of the melatonin group was higher compared to that of the control group, although it was not statistically significant (p > 0.05). The maximum torsional momentum of the CAPE group was statistically significantly high (p < 0.05). The degree of rigidity (N-m/deg) of both the melatonin and CAPE groups was higher than that of the control group and the CAPE group was found to be statistically significantly higher than the melatonin group (p < 0.05). Melatonin and CAPE increase the maturation of new bone in distraction osteogenesis. These effects are probably due to the reducing effect on bone resorption by inhibiting NF-κB and free oxygen radicals.
Physical Review B, 2006
The one-and two-orbital double-exchange models for manganites are studied using Monte Carlo compu... more The one-and two-orbital double-exchange models for manganites are studied using Monte Carlo computational techniques in the presence of a robust electron-phonon coupling ͑but neglecting the antiferromagnetic exchange J AF between the localized spins͒. The focus in this effort is on the analysis of charge transport. Our results for the one-orbital case confirm and extend previous recent investigations that showed the presence of robust peaks in the resistivity versus temperature curves for this model. Quenched disorder substantially enhances the magnitude of the effect, while magnetic fields drastically reduce the resistivity. A simple picture for the origin of these results is presented. It is also shown that even for the case of just one electron, the resistance curves present metallic and insulating regions by varying the temperature, as it occurs at finite electronic density. Moreover, in the present study these investigations are extended to the more realistic two-orbital model for manganites. The transport results for this model show large peaks in the resistivity versus temperature curves, located at approximately the Curie temperature, and with associated large magnetoresistance factors. Overall, the magnitude and shape of the effects discussed here resemble experiments for materials such as La 0.70 Ca 0.30 MnO 3 , and they are in agreement with the current predominant theoretical view that competition between a metal and an insulator, enhanced by quenched disorder, is crucial to understanding the colossal magnetoresistance ͑CMR͒ phenomenon. However, it is argued that further work is still needed to fully grasp the experimentally observed CMR effect, since in several other Mn oxides an antiferromagnetic chargeordered orbital-ordered state is the actual competitor of the ferromagnetic metal.
Physics Procedia, 2010
We investigate the one-orbital model for manganites with cooperative phonons and superexchange co... more We investigate the one-orbital model for manganites with cooperative phonons and superexchange coupling J AF via large-scale Monte Carlo (MC) simulations. Results for two-orbitals are also briefly discussed. Focusing on an the realistic electronic density n = 0.75, a regime of competition between ferromagnetic (FM) metallic and charge-ordered (CO) insulating states was identified in the finite temperature phase diagram. In the vicinity of the associated bicritical point, colossal magnetoresistance (CMR) effects were observed. The CMR magnitude is much larger than recently reported when randomly distributed polarons form the competing insulator. The appearance of CMR is associated with the development of short-distance correlations among polarons, above the spin ordering temperatures, resembling the charge arrangement of the low-temperature CO state. We present calculations of charge-charge correlations as well as typical Monte Carlo snapshots to support this view. Cengiz Şen et al. / Physics Procedia 00 (2010) 1-13 2
Physical Review Letters, 2005
Tennessee 37996 and Condensed Matter Sciences Division, Oak Ridge National Lab, TN 37381, USA
Physical Review B, 2006
Considerable progress has been recently made in the theoretical understanding of the colossal mag... more Considerable progress has been recently made in the theoretical understanding of the colossal magnetoresistance (CMR) effect in manganites. The existence of inhomogeneous states has been shown to be directly related with this phenomenon, both in theoretical studies and experimental investigations. The analysis of simple models with two competing states and a resistor network approximation to calculate conductances has confirmed that
We present a non-perturbative multi-scale extension to the Dynamical Cluster Approximation (DCA) ... more We present a non-perturbative multi-scale extension to the Dynamical Cluster Approximation (DCA) based on the two particle irreducible vertex gamma. The correlations at short length scales are calculated exactly using Quantum Monte Carlo (QMC) on small cluster of size Nc^(1), and long length scales are treated at the dynamical mean field level. Intermediate length scales are treated on a second cluster of size Nc^(2)> Nc^(1) by approximating its two-particle irreducible vertex with that of the smaller cluster, which is calculated by retaining its full momentum and frequency dependence. The resulting self energy of the large cluster is calculated using the Schwinger-Dyson equation. The method is applied to the 2D Hubbard model with cluster sizes Nc^(2)>=Nc^(1) and the results are compared with those that are calculated using QMC by increasing the size of the small cluster Nc^(1) up to Nc^(2).