The distribution of the residual lifetime and its applications

Ankara : Department of Industrial Engineering and Institute of Engineering and Sciences, Bilkent Univ., 1991.Thesis (Master's) -- Bilkent University, 1991.Includes bibliographical references.Let T be a continuous positive random variable representing the lifetime of an entitle This entity could be a human being, an animal or a plant, or a component of a mechanical or electrical system. For nonliving objects the lifetime is defined as the total amount of time for which the entitj'^ carries out its function satisfactoriljc The concept of aging involves the adverse effects of age such as increased probability of failure due to wear. In this thesis, we consider certain characteristics of the residual lifetime distribution at age t, such as the mean, median, and variance, as descril)ing aging. The following families of statistical distributions are studied from this point of view: 1. Gamma with two parameters, 2. Weil^ull with two paxameters, .3. Lognormal with two parameters, 4. Inverse Poljmomial with one parameter. Gamma and Weil)ull distrilDutions are fitted to actual data.Çağlar, Mine AlpM.S

A Comparative Performance Analyze Model and Supplier Positioning in Performance Maps for Supplier Selection and Evaluation

AbstractIn supply chain, supplier has an important role and in this situation supplier evaluation and selection is gained more significance for companies. So that, it is purposed to improve an evaluation model to evaluate and select suppliers more effectively by correlate with company's supply chain. For that reason, a form is designing to collect data from concerned company's personnel and performance measuring model which includes scoring methodology and correlation analysis that is called as “Performance-Effect” analysis in this study. With this model, it is proposed to divest supplier evaluation from its general evaluation concept by presenting alternative selection criteria, suppliers and methods for working with positioning of these in performance maps

Planimetry investigation of the corpus callosum in temporal lobe epilepsy patients

Objective: To evaluate the effects of temporal lobe epilepsy (TLE) on corpus callosum (CC) morphometry in patients with TLE. Methods: This retrospective study was conducted at the Faculty of Medicine, Tekirdag Namik Kemal University, Tekirdag, Turkey between November 2010 and December 2013. The epileptic syndrome diagnosis was based on International League Against Epilepsy criteria, and this study was conducted on the MRIs of 25 epilepsy patients and 25 control subjects. We classified the patients according to their duration of epilepsy: = 10 years. The projection area length (PAL) of the CC was also estimated. Total brain volumes (TBV) were measured on CT images. Results: The mean values of TBV for patients with TLE and the control group were not statistically different, but the CC PAL values were statistically different. The mean CC PAL values of under and over 25 years of age in patients with TLE were statistically different. The mean values of TBV of under and over 10 years duration of TLE were small statistically, but the CC PAL values were statistically different. Conclusion: The results indicate a clear influence of TLE on the structure of the CC rather than TBV

The effect of renin-angiotensin blockers on COVID-19 related mortality: A tertiary center's experience

Background: The first reports on coronaviruse disease 2019 (COVID-19) revealed an exaggerated mortality rate in hypertensive patients. In this regard, concerns about angiotensin-converting enzyme (ACE) inhibitors’ and angiotensin-receptor blockers’ (ARBs) have been aroused. Our aim in this study was to evaluate the potential bad outcome effect of hypertension and anti-hypertensive therapy on COVID-19. Methods: 183 patients with polymerase-chain-reaction (PCR)-proven COVID-19, who were admitted to our hospital and consulted to cardiology department between 15th of March and 15th of April 2020 were included. Data were recruited from hospital records. Results: Thirty-two out of 183 patients with COVID-19 died in hospital. Hypertension incidence was not statistically different between patients who survived and died (76 [50.3%] vs 19 [59.4%, p = 0.352]). Although the usage rate of ACEI were similar among groups, ARB usage rate was significantly higher in patients who died than survived (11 [34.4%] vs 23 [15.2%], p = 0.011). Binary regression analysis showed an association between ARBs and mortality (OR: 0.032, 95% CI 1.045–2.623, p = 0.032). Conclusion: Our study confirmed previous concerns regarding a potential harmful effects of ARBs on COVID-19 related mortality.Kontext: První zprávy o onemocnění koronavirem v roce 2019 (coronavirus disease 2019, COVID-19) ukazovaly na zvýšenou mortalitu jedinců s hypertenzí, což vyvolalo obavy ohledně užívání inhibitorů angiotenzin konvertujícího enzymu (ACEI) a blokátorů receptoru AT1 pro angiotenzin II (ARB). Cílem naší studie bylo posoudit možnost nepříznivého vlivu onemocnění covid-19 na závažnost hypertenze a účinnost antihypertenzní léčby. Metody: Do studie bylo zařazeno 183 pacientů s onemocněním covid-19 prokázaným PCR testem, kteří byli v období od 15. března do 15. dubna 2020 přijati do naší nemocnice a následně odesláni na kardiologickou kliniku. Údaje byly získány z nemocničních záznamů. Výsledky: Celkem 32 ze 183 pacientů s onemocněním covid-19 zemřelo v nemocnici. Incidence hypertenze se mezi pacienty, kteří přežili a zemřeli, statisticky významně nelišila (76 [50,3 %] vs. 19 [59,4 %]; p = 0,352). I když podíly pacientů užívajících inhibitory ACE byly v obou skupinách podobné, léčiva ze skupiny ARB užívalo statisticky významně více pacientů, kteří zemřeli, než těch, kteří přežili (11 [34,4 %] vs. 23 [15,2 %]; p = 0,011). Binární regresní analýza prokázala souvislost mezi užíváním ARB a mortalitou (OR: 0,032; 95% CI 1,045–2,623; p = 0,032). Závěr: Naše studie potvrdila původní obavy týkající se možných škodlivých účinků lékové skupiny ARB na mortalitu v souvislosti v onemocněním covid-19

The relationship between plasma pentraxin 3 (PTX 3) levels and endothelial function parameters determined by flow-mediated dilatation(FDM) and pulse wave analysis in hypertensive patiens

YÖK Tez ID: 448754Hipertansiyon dünyada morbidite ve mortalitenin en önemli nedenlerindendir ve giderek artan bir halk sağlığı problemi haline gelmiştir. Hipertansiyon prevelansı genel popülasyonda %30-45 civarında tespit ediştir; bu oran yaşla birlikte artış göstermektedir ve ülkeden ülkeye değişiklikler vardır. Türkiye de bu oran PatenT2 çalışmasında tüm populasyonda %31,8 olarak tespit edilmiştir. Hipertansiyon neden olduğu uç organ hasarlarıyla da klinik açıdan büyük önem taşımaktadır. Subklinik organ hasarının genel kardiyovasküler riskin belirleyicisi olarak önemi nedeniyle, organ tutulumu bulguları dikkatli bir şekilde araştırılmalıdır. Kan basıncı düzeyi yüksek olan ve olmayan bireylerde kardiyovaskuler riski belirlemede subklinik organ hasarının yaşamsal rolüne ilişkin günümüzde çok sayıda kanıt mevcuttur. Akımla bağlı genişleme (ABG)( Flow-mediated dilatationun Türkçe karşılığı olup klinikte her iki isimlendirmeyle de kullanılmaktadır. ), endotel bağımlı bir işlem olup; orta büyüklükteki musküler arterlerin shear strese maruz kalması sonucu meydana gelen hiperemiyi ölçmektedir. Tansiyon aleti manşonunun şişirilmesi ile oluşturulan shearstres'e cevaben brakiyal arterde oluşan dilatasyon esas olarak NO'in endotelden salınmasına bağlıdır ve koroner endotelyal fonksiyonun invaziv olarak değerlendirilmesi ile uyum gösterir. Arteryel stiffness damar duvarının gerilimini ve elastikiyetini belirtir. Arteryel sertlik, hipertansif hastalarda hedef organ hasarının bir göstergesidir. Pentraxin-3 (PTX-3); pentraxin süper ailesinin bir üyesidir. İnflamasyon sonucucu TNF?, IL-1ß gibi mediatörler aracılığıyla karaciğerden, endotelyal hücrelerden, aterosklerotik lezyonlardan, makrofaj ve nötrofillerden salınan akut faz proteinidir. PTX 3 seviyesinin daha önce yapılan çalışmalarda hipertansiyon, miyokard infarktüsü, preeklamsi ve kronik böbrek yetmezliği gibi hastalıklarda endotel hasarının bir göstergesi olduğu gösterilmiştir. Bizde bu çalışmamızda hipertansif hastalarda plazma pentraxin 3 seviyeleri ile fmd ve pulse wave analiz ile belirlenen noninvaziv endotelial fonksiyon göstergeleri arasındaki ilişkiyi göstermeyi planladık. Çalışmamıza 90 tane hipertansif hasta alındı. Hipertansif hastalar ambulatuar kan basıncı monitörizasyonu (AKBM) sonuçlarına göre dipper – nondipper ve grade 1 – grade 2 olarak sınıflandırıldı. Pentraxin 3 değerleri nondipper Ht grupta dipper HT gruba göre daha yüksek bulundu (p=0.028) . Pentraxin 3 değerleri grade 2 hipertansifler de grade 1 hipertansiflere göre yüksek bulunurken istatiksel olarak anlamlı değildi (p=0.219). FMD değerleri dipper HT grupta nondiper HT gruba göre anlamlı derecede iyiyken (p=0.045) ; gruplar grade 1 HT ve grade 2 HT olarak ayrıldığında FMD değerleri arasında anlamlı farklılık saptanmadı. Arteriel stiffness değerlendirmesindeki dijital volüm nabzı (DVP) parametrelerinden stiffness index (SI) ve reflection index (RI) gruplar arasında istatiksel olarak anlamlı farklılık saptanmadı. Sonuç olarak tüm grubun Pentraxin 3 (PTX3) düzeyleri ile akıma bağlı dilatasyon (FMD) değerleri arasında yapılan korolesyon analizi sonucu PTX 3 ve FMD arasında negatif korelasyon saptandı ( r:-0.297 P:0.05 ) . PTX 3 ve SI ile yapılan korelasyon analizi sonucu pozitif korelasyon saptandı (r:0,603 P:0.01).Yine PTX 3 ve RI le yapılan korelasyon analizi sonucu pozitif korelasyon saptandı (R:0.240P:0.025). Bu veriler ışığında hipertansif hastalardaki pentraxin 3 düzeylerinin endotel fonksiyon parametrelerinden FMD ve arteriel stifness göstergelerinden SI ve RI değerleri arasındaki korelasyon hipertansif hastaların uç organ hasarı ve endotel disfonsiyonu göstermede biyokimyasal bir parametre olan pentraxin 3 ün kullanılabileceği fikrini vermektedir. Ancak bu konuda benzer sonuçlarla desteklenen daha fazla ve büyük çalışmalara ihtiyaç vardır.Hypertension (HT) is one of the leading causes of morbidity and moratlity and incresing healtj problem. HT prevalance is approximately %30-45 in general population, increases with age and shows different notes among races and countries. Patent2 trial demonstrated %31.8 rate of HT in Turkey. HT reveals a significant importance ue to its end organ damage. The end organ dysfunction must be carefully eveluated. There is an increasing evidence of vital role of subclinical end organ damage in evoluating cardiovascular risk in both hypertensive and non hypertensive patiens. Flow mediated dilatation (FMD)which is an endothel independent procedure measures the hypermia occuring due to shear stress in the mid-sized muscular artereies. Dilatation in the brachial artery is due to the release of NO and is associated with invasive evoluiation of endothelial function. Arterial stiffness specifies vessel wall stres and elasticity. Arterial stiffnes is a hallmark of end organ damage in hypertensive patients. Pentraxin 3 (PTX 3) is a member of pentraxin super family. İt is an acute phase protein released from endothelial cells, atherosklerotic lesions, macrophages and neutrofils as a result of inflamation. PTX3 is show to be a marker of endothelial damage in HT, AMI, preeclempsia and chronic kidney disease. In this study we aimed to find an association between PTX 3 and FMD and PWA as noninvasive endothelial function indicators. 90 hypertensive patients, were included in the study . The patients were categorized into dipper and nondipper and grade 1 and grade 2 according to ABPM records. Pentraxin 3 levels were significanty higher in the nondipper group (p=0.028). PTX3 levels were insignificantly higher in the grade 2 hypertensives relative to grade 1 (p=0.219). FMD values were significantly beter (p=0.045)in dipper hypertensives relative to nondipers but this signifance was not present between grade 1 and grade 2 hypertensives. Stiffness index (SI) and reflection index (RI) were not statistically different between the groups. In conclusıon, PTX 3 and FMD were negativly correlated ( R:-0.297P:0.05 ) . PTX 3 and SI were positively correlated (R:0,603P:0.01).Also PTX 3 and RI was positively correlated (R:0.240P:0.025). In this concept, PTX 3 levels in hypertensive patiens may be used as a marker of end organ damage and endothelial dysfunction, due to the corelation between PTX 3 and FMD and RI and SI further prospective studies are needed to support the results of this study

Hipertansif hastalarda plazma pentraxin 3 (PTX3) seviyeleri ile FMD (flow - mediated dilatation) ve pulse wave analiz ile belirlenen noninvaziv endotelial fonksiyon göstergeleri arasındaki ilişki

Tez (Tıpta Uzmanlık) -- Kırıkkale Üniversitesi100399

Akut Koroner Sendromlu Hastalarda Çok Damar Hastalığı ile Kardiyovasküler Risk Faktörleri Arasındaki İlişki

Amaç: Akut koroner sendrom olgularında ciddi darlık olan koroner arter sayısı ile kardiyovasküler risk faktörleri arasındaki ilişki değerlendirildi. Yöntemler: Bu çalışma retrospektif olarak dizayn edildi. 2016–2018 tarihleri arasında akut koroner sendrom sebebiyle koroner anjiografi yapılan 904 hasta çalışmaya dahil edildi. Ciddi koroner arter darlığı olmayan ve koroner operasyon geçiren hastalar çalışma dışı bırakıldı. Hastalar kritik koroner arter darlıklarına göre tek damar hastalığı (TDH) ve çok damar hastalığı (ÇDH) olacak şekilde iki gruba ayrıldı. ÇDH ile TDH olanlar klasik kardiyovasküler risk faktörleri açısından karşılaştırıldı. Bulgular: Hastaların 544’ünde (%60) ÇDH 365’inde (%40) TDH saptandı. ÇDH olan grupta yaş, hipertansiyon ve diyabet mellitus istatistiksel olarak daha fazla saptandı (sırasıyla p<0.001, p=0.003, p=0.005). TDH olan grupta ise erkek cinsiyet, aile öyküsü ve sigara içiciliği istatistiksel olarak daha fazla saptandı (sırasıyla p=0.006, p<0.001, p<0.001). Sonuç: Diyabet ve hipertansiyon ÇDH grubunda yüksek saptanırken aile öyküsü ve sigara içiciliği TDH grubunda yüksek saptandı. Akut koroner sendrom hastalarında bu risk faktörlerin göz önünde bulundurulması önemlidir.Aim: The relationship between the number of coronary arteries with severe stenosis and cardiovascular risk factors was evaluated in patients with acute coronary syndrome. Material-Method: This study was designed retrospectively. 904 patients who underwent coronary angiography for acute coronary syndrome between 2016–2018 were included in the study. Patients who underwent coronary bypass surgery and didn’t have severe coronary artery disease were excluded. The patients were divided into two groups according to critical coronary artery stenosis as single vessel disease and multiple vessel disease. The relationship between multivessel disease and risk factors was compared. Results: Multivessel disease was detected in 544 (60%) patients and single vessel disease in 365 (40%) patients. Age, hypertension and diabetes were found to be higher in multivessel disease (respectively p<0.001, p=0.003, p=0.005). Male gender, family history and smoking were found to be higher in the single vessel disease. Conclusion: Diabetes and hypertension were higher in multivessel disease group, while family history and smoking were higher in single vessel disease group. It is important to consider these risk factors in patients with acute coronary syndrome

The Association Between Multivessel Disease and Cardiovascular Risk Factors in Patients with Acute Coronary Syndrome

Amaç: Akut koroner sendrom olgularında ciddi darlık olan koroner arter sayısı ile kardiyovasküler risk faktörleri arasındaki ilişki değerlendirildi. Yöntemler: Bu çalışma retrospektif olarak dizayn edildi. 2016–2018 tarihleri arasında akut koroner sendrom sebebiyle koroner anjiografi yapılan 904 hasta çalışmaya dahil edildi. Ciddi koroner arter darlığı olmayan ve koroner operasyon geçiren hastalar çalışma dışı bırakıldı. Hastalar kritik koroner arter darlıklarına göre tek damar hastalığı (TDH) ve çok damar hastalığı (ÇDH) olacak şekilde iki gruba ayrıldı. ÇDH ile TDH olanlar klasik kardiyovasküler risk faktörleri açısından karşılaştırıldı. Bulgular: Hastaların 544’ünde (%60) ÇDH 365’inde (%40) TDH saptandı. ÇDH olan grupta yaş, hipertansiyon ve diyabet mellitus istatistiksel olarak daha fazla saptandı (sırasıyla p<0.001, p=0.003, p=0.005). TDH olan grupta ise erkek cinsiyet, aile öyküsü ve sigara içiciliği istatistiksel olarak daha fazla saptandı (sırasıyla p=0.006, p<0.001, p<0.001). Sonuç: Diyabet ve hipertansiyon ÇDH grubunda yüksek saptanırken aile öyküsü ve sigara içiciliği TDH grubunda yüksek saptandı. Akut koroner sendrom hastalarında bu risk faktörlerin göz önünde bulundurulması önemlidir.Aim: The relationship between the number of coronary arteries with severe stenosis and cardiovascular risk factors was evaluated in patients with acute coronary syndrome. Material-Method: This study was designed retrospectively. 904 patients who underwent coronary angiography for acute coronary syndrome between 2016–2018 were included in the study. Patients who underwent coronary bypass surgery and didn’t have severe coronary artery disease were excluded. The patients were divided into two groups according to critical coronary artery stenosis as single vessel disease and multiple vessel disease. The relationship between multivessel disease and risk factors was compared. Results: Multivessel disease was detected in 544 (60%) patients and single vessel disease in 365 (40%) patients. Age, hypertension and diabetes were found to be higher in multivessel disease (respectively p<0.001, p=0.003, p=0.005). Male gender, family history and smoking were found to be higher in the single vessel disease. Conclusion: Diabetes and hypertension were higher in multivessel disease group, while family history and smoking were higher in single vessel disease group. It is important to consider these risk factors in patients with acute coronary syndrome