Alper Yıldırım - Academia.edu (original) (raw)

Papers by Alper Yıldırım

Journal of global optimization, May 30, 2024

IET wireless sensor systems, Apr 4, 2024

Mathematical programming, Mar 6, 2024

We study linear programming relaxations of nonconvex quadratic programs given by the reformulatio... more We study linear programming relaxations of nonconvex quadratic programs given by the reformulation-linearization technique (RLT), referred to as RLT relaxations. We investigate the relations between the polyhedral properties of the feasible regions of a quadratic program and its RLT relaxation. We establish various connections between recession directions, boundedness, and vertices of the two feasible regions. Using these properties, we present a complete description of the set of instances that admit an exact RLT relaxation. We then give a thorough discussion of how our results can be converted into simple algorithmic procedures to construct instances of quadratic programs with exact, inexact, or unbounded RLT relaxations.

Journal of Crohn's and colitis, 2024

Background: In this study, we aimed to evaluate the demographic and epidemiological trends of Ulc... more Background: In this study, we aimed to evaluate the demographic and epidemiological trends of Ulcerative Colitis (UC) and Crohn's Disease (CD) in non-endemic era for inflammatory bowel disease (IBD) during the past three decades. Methods: UC and CD patients who had follow-up at least 6 months between June 1993 and February 2023 were evaluated retrospectively. Electronic medical databases, personal queries and IBD registries have all been used to collection data on the clinical and demographic characteristic of all patients. Results: A total of 1549 adult patients with UC and CD were admitted to study. UC was diagnosed in 873 (56.4%) patients (Male 538, 61.6%) and CD was diagnosed in 676 (43.6%) patients (Male 404, 59.8%). The median follow-up duration was 8.3 years for UC patients and 6.8 years for CD patients. In patients with UC, proctitis was 154 (17.6%), left sided colitis was 410 (47%) and extensive colitis was 309 (35.4%). In CD patients, ileal involvement was found in 297 (43.9%), colonic in 76 (11.2%), ileo-colonic in 299 (44.2%) and isolated upper GI involvement in 4 (0.6%) cases. 529 (78.3%) patients had non-stenosing non-penetrating behavior, 45 (6.7%) had stenosing behavior, 102 (15.1%) had penetrating behavior, as well as 196 (29%) patients had perianal disease. Mesalazine 658 (75.4%) and thiopurine 397 (45.5%) were the most frequently used conventional treatments for UC, while thiopurine 304 (45%) was most commonly used for CD patients. In the last two-decade, proportion of the biologic usage were 27.9% and 32.1% in UC patients 28.5% and 31.4% in CD patients respectively. Over the three decades, abdominal surgery was 49.2%, 27.8% and 36.3% in CD and colectomy rates was 2.0%, 2.7% and 3.7% in UC patients. While the rate of UC patients has slightly decreased to 98 (61.6%), 401 (58.5%) and 374 (53%) frequency of CD patients has increased to 61 (38.4%), 284 (41.5%) and 331 (47%). Over the course of three decades, there were more UC patients than CD patients, however proportion of UC/CD has been continuously decreased (1.61, 1.41 and 1.13) for three decades respectively. Conclusion: Our study showed that the frequency of UC and CD has significantly increased during the previous three decades in non-endemic era for IBD. While the frequency of UC patients has slightly decreased, that of CD patients has steadily increased over the past three decades. Although the use of biologics has significantly increased, proportions of the abdominal surgeries and colectomies has not prominently changed.

Eskişehir Osmangazi Üniversitesi Sosyal Bilimler Dergisi, Aug 9, 2023

Collaborations established within the framework of energy can directly affect regional policies. ... more Collaborations established within the framework of energy can directly affect regional policies. TAPI Natural Gas Pipeline Project, which was created to transport Turkmenistan gas to South Asia via Afghanistan, was shaped in line with the economic and security expectations of the regional states. The maintenance of the TAPI project is fundamentally based on the stability of the economy and security. Since Afghanistan's security problems negatively affect the economic interests of the parties, this problem is no longer just Afghanistan's issue. This article, which uses a broader understanding of the concept of energy diplomacy, energy infrastructure, such as the TAPI project beyond the member states of interdependence can be used to promote discusses how increasing the number of stakeholders.

Cukurova Medical Journal, Mar 31, 2021

mac: Bu calismda melatonin on-tedavisinin, sicanlarda mide ulserine bagli gerceklesen mikrobiyota... more mac: Bu calismda melatonin on-tedavisinin, sicanlarda mide ulserine bagli gerceklesen mikrobiyota degisimine ve oksidatif hasara karsi koruyucu etkilerini arastirmak hedeflenmistir. Gerec ve Yontem: Wistar albino sicanlara (n=32) 12 gun boyunca icme suyu, melatonin (4mg/kg/gun), antibiyotik karisimi (AB; 1 g/L ampisilin + 1 g/L neomisin+ 1 g/L metronidazol), melatonin+ AB icme suyunda verildi. Ardindan ulser olusturuldu. Katkisiz icme suyu alan sicanlarin yarisina cerrahi islem yapildi ama asetik asit uygulanmadi (kontrol grubu; n=8). Cerrahi sonrasindaki 3 gun boyunca uygulanan tum tedavilere devam edildi. Mide dokulari biyokimyasal ve histopatolojik incelemeler icin cikarildi. Rektumdan alinan fekal ornekler bakteriyolojik olcumler icin uygun kosullarda saklandi. Bulgular: Tedavi almayan ulser grubunun mide dokusunda MDA, MPO, 8-OHdG, luminol ve lusigenin kemiluminesans seviyeleri, TNF-α ve IL-8 protein ekspresyonlari kontrol grubuna gore anlamli derecede artarken, antioksidan GSH seviyesinin azaldigi gozlendi. Melatonin+AB on-tedavi uygulamasi antioksidan GSH seviyesini ve anti-inflamatuvar IL-10 miktarini artirmis, kaspaz-3 aktivitesini baskilamis ve dokuya notrofil gocunu kontrol duzeyine inecek sekilde azaltmistir. Sonuc: Etkin bir antioksidan ve radikal supurucu olan melatoninin antibiyotik ile birlikte verilmesinin, ulser iyilesmesini hizlandirmada ve kolondaki dagilimi bozulan bakteriyel cesitliligi duzeltmede daha etkili olacagi ongorulmektedir.

TURKDERM

Background and Design: Although some inflammatory markers were elevated in patients with psoriati... more Background and Design: Although some inflammatory markers were elevated in patients with psoriatic arthritis (PsA) compared to healthy controls, are few studies evaluated the effects of systemic treatments for PsA on these markers. The aim of this study is to investigate the changes in hemogram parameters and C-reactive protein (CRP) in PsA patients receiving systemic therapies. Materials and Methods: In this retrospective study, hemogram parameters, CRP, and systemic inflammation indices [neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio, systemic immune-inflammation index (SII), and systemic inflammation response index (SIRI)] of 50 PsA patients were analyzed before and in the third month of the treatments. Results: While mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and hemoglobin (Hb) were higher in the third month of all treatments compared to the baseline (p=0.009, 0.003, and 0.036, respectively), platelet, CRP and SII were lower (p=0.001, 0.000, and 0.000, respectively). In the biological therapy group (n=21), platelet, SIRI, and SII were lower, while MCHC was higher in the third month than baseline (p=0.023, 0.033, 0.000, and 0.003, respectively). CRP and SII were lower in the third month of the non-biologic treatment group (n=29) compared to the baseline, and MCH and mean corpuscular volume (MCV) were higher (p=0.001, 0.000, 0.027, and 0.044, respectively). No statistically different changes were recorded in NLR, PLR, and other parameters. Conclusion: Hb, MCH, and MCHC increased, and platelet, CRP, and SII decreased in the third month of all systemic therapies. MCV was higher in the non-biologic treatment group, and SIRI was lower in the biological treatment group in the third month than baseline. Therefore, these parameters may be useful for monitoring the effects of treatments in PsA.

Zenodo (CERN European Organization for Nuclear Research), Jun 6, 2023

Zenodo (CERN European Organization for Nuclear Research), Jun 15, 2023

Arteriosclerosis, Thrombosis, and Vascular Biology, May 1, 2012

It is well recognized that different pathological conditions associated with inflammation are als... more It is well recognized that different pathological conditions associated with inflammation are also accompanied by altered platelet function and enhanced thrombus development. Experimental colitis (induced by dextran sodium sulfate, DSS) and angiotensin II (AngII)-induced hypertension (HTN) are two examples of pathologically distinct inflammation models that exhibit enhanced platelet adhesion in venules and accelerated thrombus formation in arterioles. Whether these responses represent alterations in platelet production, life-span, and/or function remains unclear. In this study, we compared the changes in platelet production and reactivity (to thrombin) that occur in murine models of DSS colitis and AngII-induced HTN. Mature (TO-) and immature (TO+) platelets in blood were quantified using thiazole orange (TO) staining with flow-cytometry. The in vivo biotinylation method was used to determine the life-spans of TO+ and TO- platelets. Platelet aggregation velocity was measured using a low-angle light scattering technique. Thrombus formation, induced by light/dye injury, was monitored in cremaster muscle arterioles and platelet adhesion was quantified in the venules. Our findings indicate that both models of inflammation promote platelet adhesion and enhanced thrombus formation in the microvasculature. The enhanced thrombosis normally detected in both DSS-induced colitis and AngII-induced hypertension models was not evident in interleukin-6 (IL-6) deficient mice and in WT mice treated with an IL-6 receptor blocking antibody. DSS colitis was accompanied by an increased appearance of both TO+ and TO- platelets, increased platelet reactivity (aggregation) to thrombin, and no change in platelet turnover. The AngII HTN model exhibits an increase in platelet turnover, an increased number of TO- (but not TO+) platelets, and no change in platelet aggregation, suggesting that an altered endothelial cell phenotype likely makes a larger contribution to the accelerated arteriolar thrombosis in this model. The divergent responses in these two IL-6 dependent models of microvascular thrombosis may reflect the relative importance of platelets and microvascular endothelial cells as molecular targets for IL-6 mediated thrombogenic responses.

The FASEB Journal, Apr 1, 2015

AngII-induced hypertension is associated with accelerated thrombus formation and leukocyte recrui... more AngII-induced hypertension is associated with accelerated thrombus formation and leukocyte recruitment. The objective of this study was to evaluate the mechanisms underlying the prothrombogenic-pro...

Osmaniye Korkut Ata Üniversitesi Fen Bilimleri Enstitüsü dergisi, Mar 10, 2023

European Radar Conference, Oct 1, 2016

Radar warning receivers (RWRs) classify the intercepted pulses into clusters utilizing multiple p... more Radar warning receivers (RWRs) classify the intercepted pulses into clusters utilizing multiple parameter deinterleaving. In order to make classification more elaborate time-of-arrival (TOA) deinterleaving should be performed for each cluster. In addition, identification of the classified pulse sequences has been exercised at last. It is essential to identify the classified sequences with a minimum number of pulses. This paper presents a method for deinterleaving of intercepted signals having small number of pulses that belong to stable or jitter pulse repetition interval (PRI) types in the presence of missed pulses. It is necessary for both stable and jitter PRI TOA deinterleaving algorithms to utilize predefined PRI range. However, jitter PRI TOA deinterleaving also requires variation about mean PRI value of emitter of interest as a priori.

Clean Technologies and Environmental Policy, Sep 7, 2022

The main objective of passive Electronic Warfare (EW) systems is to receive radar signals, measur... more The main objective of passive Electronic Warfare (EW) systems is to receive radar signals, measure parameters of signals, deinterleave and identify composed clusters of pulses. In a dense environment, identification of each radar signals has had vital importance. Nowadays, EW systems use multi-parameters deinterleaving methods to compose clusters from receiving radar pulses. Then, these clusters are identified by using time of arrival (TOA) deinterleaving methods. In this paper, we will discuss a new deinterleaving algorithm based on predefined parameters for radars which emit stagger and dwell-switch pulse repetition interval (PRI) types. The results of proposed algorithm are simulated via test scenario.

SAE technical paper series, Apr 3, 2006

Abstract: This paper describes the use of a designed Fuzzy Logic Control for the purpose of integ... more Abstract: This paper describes the use of a designed Fuzzy Logic Control for the purpose of integrating the driver¿s steering input together with the four-wheel steering system (4WS) in order to improve the vehicle¿s dynamic behavior with respect to yaw rate and body sideslip angle. The ...

European mechanical science, Dec 20, 2022

Sea currents have the potential to supply electricity from a renewable energy source to coastal r... more Sea currents have the potential to supply electricity from a renewable energy source to coastal regions. The assessment of the potential energy that could be generated is the first step toward developing this resource. In this study, the data was collected at 5 m and 35 m depths below the sea surface level, including sea current velocity and direction. A detailed field measurement, of the probability of sea water velocity at three stations (Antalya, Silivri, Istanbul) for 5 months is carried out. The sea current power density values in these stations were 10.41, 4.92, and 7.91 W/m 2 at 5 m depth, respectively. Besides, average sea current power density values were seen to be closely arranged with 11.44, 4.07, and 9.06 W/m 2 at 35 depths, respectively. In addition, statistical analysis applying Weibull and Rayleigh models is also presented. It is shown that the use of a Weibull probability distribution facilitates the analysis of sea velocity conditions and is also able to predict the power density with a high degree of accuracy. The results of this study are useful for the understanding of the marine hydrokinetic energy of these areas, where sea current power projects may be started in Turkey.

Bilgisayar bilimleri, Sep 16, 2022