24 research outputs found
On the behavior of the solutions of the system of rational difference equations
There has been a great interest in studying difference equations and systems. One of the reasons for this is a necessity for some techniques which can be used in investigating equations arising in mathematical models describing real life situations in population biology, geometry, economics, probability theory, genetics, physics etc
Toplam elektrik üretimi ve ekonomik büyüme ilişkisi: Türkiye örneği (1980-2010)
Elektrik tüketiminin birçok ülkede ekonomik faaliyetlerle doğrudan ilişkili olduğu bilinmektedir. Elektrik talebindeki artışın nedenleri genellikle daha yüksek yaşam standartları ve sanayileşmedir. Gelişmekte olan
diğer ülkelerdeki gibi Türkiye’de de enerji ve elektrik enerjisi talebi, sosyal ve ekonomik gelişmeler ile ülke
nüfusundaki artıştan dolayı çok hızlı bir şekilde artmaktadır. Bu nedenle artan elektrik talebini karşılamak ve
elektriğin arz yetersizliğini gidermek için Türkiye’de elektrik enerjisine yönelik yatırımların süreklilik arz etmesi gerektiği söylenebilir. Bu çalışmada 1980-2010 dönemi için Vektör Hata Düzeltme Modeli (VECM) kullanılarak, Türkiye’de elektrik enerjisi üretimi ve ekonomik büyüme arasında sistematik bir ilişki olup olmadığının
incelenmesi amaçlanmıştır. Bu nedenle ilk aşamada elektrik üretimi ve GSYİH arasındaki Ko-entegrasyon derecesi incelenerek, değişkenlerin birinci dereceden eş-bütünleşik olduğu belirlenmiştir. İkinci aşamada elektrik
üretimi ve GSYİH arasındaki uzun dönemli ilişki araştırılmıştır. Üçüncü aşamada uzun dönemli ilişki tahmin
edilmiş ve Vektör Hata Düzeltme Modeli kullanılarak en nihayetinde nedensellik sınaması yapılmıştır. Elde
edilen bulgularda toplam elektrik üretimi ile GSYİH arasında uzun dönemde tek yönlü bir nedensellik ilişkisi
bulunmuştur. Diğer bir ifadeyle herhangi bir geri bildirim etkisi olmaksızın ekonomik büyümeden toplam elektrik üretimine doğru işleyen tek yönlü bir nedensellik olduğu tespit edilmiştir. Dolayısıyla Türkiye’de ekonomik
büyümenin daha fazla elektrik üretimini teşvik edeceği ileri sürülebilir
Absolute dimensions of solar-type eclipsing binaries : NY Hya: a test for magnetic stellar evolution models
Funding: Europlanet 2024 RI has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 871149. N.P.’s work was supported by Fundação para a Ciência e a Tecnologia (FCT) through the research grants UIDB/04434/2020 and UIDP/04434/2020. U.G.J. acknowledges funding from the Novo Nordisk Foundation Interdisciplinary Synergy Programme grant no. NNF19OC0057374 and from the European Union H2020-MSCA-ITN-2019 under Grant no. 860470 (CHAMELEON). J.V. acknowledges support from the Grant Agency of the Czech Republic (GACR 22-34467S). J.C.M. acknowledges financial support by Spanish grants PID2021-125627OBC31 funded by MCIU/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”, PGC2018-098153-B-C33 funded by MCIU/AEI, by the programme Unidad de Excelencia María de Maeztu CEX2020-001058-M, and by the Generalitat de Catalunya/CERCA programme. P.L.P. was partly funded by Programa de Iniciación en Investigación-Universidad de Antofagasta. INI-17-03.The binary star NY Hya is a bright, detached, double-lined eclipsing system with an orbital period of just under five days with two components each nearly identical to the Sun and located in the solar neighbourhood. The objective of this study is to test and confront various stellar evolution models for solar-type stars based on accurate measurements of stellar mass and radius. We present new ground-based spectroscopic and photometric as well as high-precision space-based photometric and astrometric data from which we derive orbital as well as physical properties of the components via the method of least-squares minimisation based on a standard binary model valid for two detached components. Classic statistical techniques were invoked to test the significance of model parameters. Additional empirical evidence was compiled from the public domain; the derived system properties were compared with archival broad-band photometry data enabling a measurement of the system's spectral energy distribution that allowed an independent estimate of stellar properties. We also utilised semi-empirical calibration methods to derive atmospheric properties from Str\"{o}mgren photometry and related colour indices. Data was used to confront the observed physical properties with classic and magnetic stellar evolution models.Peer reviewe
Transits of Known Planets Orbiting a Naked-Eye Star
© 2020 The American Astronomical Society. All rights reserved.Some of the most scientifically valuable transiting planets are those that were already known from radial velocity (RV) surveys. This is primarily because their orbits are well characterized and they preferentially orbit bright stars that are the targets of RV surveys. The Transiting Exoplanet Survey Satellite (TESS) provides an opportunity to survey most of the known exoplanet systems in a systematic fashion to detect possible transits of their planets. HD 136352 (Nu2 Lupi) is a naked-eye (V = 5.78) G-type main-sequence star that was discovered to host three planets with orbital periods of 11.6, 27.6, and 108.1 days via RV monitoring with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph. We present the detection and characterization of transits for the two inner planets of the HD 136352 system, revealing radii of 1.482-0.056+0.058 R ⊕ and 2.608-0.077+0.078 R ⊕ for planets b and c, respectively. We combine new HARPS observations with RV data from the Keck/High Resolution Echelle Spectrometer and the Anglo-Australian Telescope, along with TESS photometry from Sector 12, to perform a complete analysis of the system parameters. The combined data analysis results in extracted bulk density values of ρb = 7.8-1.1+1.2 g cm-3 and ρc = 3.50-0.36+0.41 g cm-3 for planets b and c, respectively, thus placing them on either side of the radius valley. The combination of the multitransiting planet system, the bright host star, and the diversity of planetary interiors and atmospheres means this will likely become a cornerstone system for atmospheric and orbital characterization of small worlds.Peer reviewe
Prevalence of bone and soft tissue tumors
Amaç: Kemik ve yumuşak doku tümörlerinin tanı ve tedavisi için multidisipliner yaklaşım gereklidir. Bu amaçla kurulan Ege Üniversitesi İskelet Sistemi Tümörleri Konseyi, 1989-2009 yılları arasında iskelet sistemi tümörü ön tanısı ile yaklaşık 6,000 hastayı değerlendirmiştir. Çalışmamızda bu hasta grubundan elde edilen demografik verilerin sunulması amaçlanmıştır. Çalışma planı: İskelet sitemi tümörü şüphesi taşıyan 5,658 hasta geriye dönük olarak değerlendirilmiştir. Konseyde birden çok görüşülen hastaların tekrarlayan kayıtları çalışmadan çıkartılmıştır. Bulgular: Toplam 5,658 olgunun %39.7'si habis mezenkimal tümörlü hastalardır. Selim tümörler %17, tümör benzeri lezyonlar %17.8, metastazlar ise %8.6 oranında bulunmuştur. Sarkomların %50.2'si kemik, %49.8'i yumuşak doku kökenlidir. Habis kemik tümörleri içinde osteosarkomlar %33.6, Ewing-PNET %25.5, habis kıkırdak tümörleri %19.4, hematopoetik habasetler ise %17.6 olarak bulunmuştur. Yumuşak doku sarkomları içinde pleomorfik hücreli sarkomlar %24.5, liposarkomlar %16.4, sinovyal sarkom %13, indifferansiye sarkomlar ise %8.8 oranındadır. Selim tümörlerin %48'i yumuşak doku tümörleri, %28'i selim kıkırdak tümörleri, %15'i dev hücreli kemik tümörü ve %9'u osteojenik selim tümörlerdi. Hemanjioma, lipoma, agresif fibromatozis, enkondroma, soliter kondroma ve osteoid osteoma gruplarında en sık görülen selim tümörlerdi. Kemikte görülen tümör benzeri lezyonların %15.9'u anevrizmal kemik kisti, %15.3'ü fibröz displazi ve %5'i basit kemik kisti olarak bulunmuştur. Kemikteki karsinom metastazları içinde akciğer kanser metastazları %27, meme kanser metastazları %24, gastrointestinal kanser metastazları %10.5 ve böbrek kanser metastazları %8.2 oranında görülmüştür. Çıkarımlar: Kemik ve yumuşak doku tümörlerinin tanısal dağılımı konusunda Türkiye de geniş istatistiksel bir çalışma yoktur. Çalışmamızın bu konuya katkı sağlayacağını düşünüyoruz.Objective: Multidisciplinary approach is a necessity for the appropriate diagnosis and treatment of bone and soft tissue tumors. The Ege University Musculoskeletal Tumor Council offers con- sultation services to other hospitals in the Aegean region. Since 1988 the Council has met week- ly and spent approximately 1,500 hours evaluating almost 6,000 patients with suspected skeletal system tumors. Our objective was to present the data obtained from this patient group. Methods: A total of 5,658 patients, suspected to have a musculoskeletal tumor, were evaluated retrospectively. Multiple records of the patients due to multiple attendance to the Council were excluded. The prevalance of the bone and soft tissue tumors in these patients were analysed. Results: Malignant mesenchymal tumors accounted for 39.7% of the total patients, benign tumors for 17%, tumor-like lesions for 17.8% and metastatic carsinomas for 8.6%. Malignant bone tumors were 50.2% and malignant soft tissue tumors were 49.8% of all the sarcomas. Among the malignant bone tumors the most common was osteosarcomas at a rate of 33.6%, fol- lowed by Ewing-PNET at 25.5%, chondrosarcomas at 19.4% and haematopoietic tumors at 17.6%. Pleomorphic sarcomas (24.5%), liposarcoma (16.4%), synovial sarcoma (13%) and undifferential sarcomas (8.8%) were the most common types of malignant sof tissue tumors. Benign soft tissue tumors (48%), benign cartilage tumors (28%), giant cell tumor (15%) and osteogenic tumors (9%) were found among the benign tumors. Hemangioma, lipoma, agressive fibromatosis, enchondroma, solitary chondroma and osteoid osteoma were the most common tumors in their groups. Lung (27%), breast (24%), gastrointestinal system (10.5%) and kidney (8.2%) carcinomas were the most common primary sites of the bone metastasis. Conclusion: Turkey still lacks a comprehensive series indicating the incidence and diagnostic distribution of bone and soft tissue tumors. The presented data would add to our knowledge on the specific rates of the bone and soft tissue tumors in Aegean region
The effects of implanted valve sizes on ventricular hypertrophy in aortic stenosis
WOS: 000300797800013PubMed: 22306570Amaç: İzole aort darlığına bağlı aort kapak replasmanı yapılan vakalarda, vücut yüzey alanına göre kapak ölçülerinin, aortik gradiyent ve sol
ventrikül hipertrofisi üzerindeki etkilerini sunmayı amaçladık.
Yöntemler: Ciddi aort stenozu nedeniyle Ocak 2006- Nisan 2007 tarihleri arasında aort kapak replasmanı yapılan hastalar (12’ si erkek,15’i kadın;
toplam 27 ), post-operatif 4. ve 6. aylarda ekokardiyografileri yapılarak prospektif olarak takip edildi. Hastalar operasyon sırasında replase edilen
mekanik aort kapak ölçülerine göre iki gruba (19-21 mm ve 23-25 mm) ayrıldı. İki gruba ait primer sonlanım noktası değişkenleri olan renkli ve
sürekli dalga Doppler ekokardiyografi ile ölçülen aort kaçak varlığı, sol ventrikül kitle indeksi (SVKİ) ve ortalama transaortik gradiyentleri karşılaştırıldı. Gruplararası karşılaştırmalarda Fischer tam testi ve Mann-Whitney U testi, grup içi analizde Freidman testi kullanıldı.
Bulgular: Aort kapaktaki ortalama sistolik gradiyent (OSG) ve SVKİ'de preoperatif ve postoperatif değerler kıyas edildiğinde, 23 mm ve 25 mm
kapaklarda, istatistiksel olarak anlamlı gerilemeler bulundu (p<0.01). Preoperatif ve postoperatif ekokardiyografik verilerle, özellikle sol ventrikül
kitlesi, SVKİ, pik sistolik gradiyent ve OSG değerlerinde gerilemelerin belirgin olduğu bulundu. Bu gerilemeyle ilişkili değerler, 4. ayda da tespit
edilebilir seviyedeyken, asıl anlamlı gerilemenin postoperatif 6.ayda olduğu gözlendi. Diğer taraftan 19 mm ve 21 mm kapaklar için elde edilen
değerler istatistiksel olarak diğerlerinden (23 mm ve 25 mm) daha az anlamlı bulundu (p<0.05’e karşı p<0.01).
Sonuç: Aort kapak replasmanında uygun kapak ölçülerinin seçiminde yaş, cinsiyet ve aktivite, gibi faktörler önemlidir. Ancak hastanın vücut
yüzey alanına göre kapak ölçüsü daha önemli olan kriterdir. (Anadolu Kardiyol Derg 2012; 12: 165-70)Objective: We aimed to study the effects of the valve sizes according to body surface area on aortic gradient and ventricular hypertrophy in the cases of aortic valve replacement due to isolated aortic stenosis. Methods: Between January 2006 and April 2007, patients (12 men, 15 women; totally 27) followed up prospectively with echocardiography fourth and sixth month postoperatively. The patients were divided into two groups according to the prosthetic aortic valve diameters (19-21 mm vs 23-25 mm). The primary endpoints between the two groups (aortic regurgitation, left ventricular mass index and transvalvular gradient measured by color and continuous wave Doppler) were compared. Fischer exact test and Mann-Whitney U test were used for intergroup comparison whereas intragroup analysis was done with Freidman test. Results: Mean systolic gradient and left ventricular mass index were significantly reduced in 23 mm and 25 mm valves (p<0.01) in the postoperative follow-up. In addition, especially, decline in the values of left ventricular mass, left ventricular mass index, peak systolic gradient and the mean systolic gradient were found to be significant. These values associated with regression were detectable at the postoperative 4th month, but actual significant regression was observed at the postoperative 6th month (p<0.01). On the other hand, the values obtained for 19 mm and 21 mm valves also showed significant progress (p<0.05). Conclusion: Factors such as age, gender and activity are important in the selection of appropriate valve sizes in aortic valve replacement. However, the patient's body surface is the most important prognostic factor compared to others. (Anadolu Kardiyol Derg 2012; 12: 165-70
The Comparison of Inflammatory Response in Off-Pump and OnPump Coronary Bypass Surgery
Amaç: Bu çalışmamızda off-pump ve on-pump yöntemi ile koroner bypass operasyonu yapılan hastalardaki inflamatuar yanıtta önemli olan tümör nekrozis faktör-alfa (TNF-?) ile Creaktif protein (CRP) değerleri karşılaştırılarak klinik yansımaları incelenmiştir. Çalışma planı: Kliniğimizde koroner bypass operasyonu yapılan 40 hasta çalışmaya alındı. Birinci grup on- pump hastaları (Grup I, n20), ikinci grup ise off pump (Grup II, n20) hastalarından oluşturuldu. Her iki grupta operasyondan bir gün önce ve postoperatif 6.saatte tümör nekrozis faktör, ayrıca operasyondan bir gün önce, postoperatif 1. ve 3. günlerde C-reaktif protein ile akyuvar düzeylerine bakıldı. Sonuçlar: Karşılaştırdığımız tümör nekrozis faktör düzeylerinde preoperatif dönemde anlamlı bir fark izlenmezken (p0.098), postoperatif dönemdeki tümör nekrozis faktör düzeyleri Grup Ide anlamlı olarak daha yüksek bulundu (p0.016). Her iki gruptaki preoperatif C-reaktif protein düzeyleri arasında anlamlı bir fark bulunmazken (p0.074), Grup Ide postoperatif 1. ve 3. gündeki C-reaktif protein düzeyleri anlamlı olarak daha yüksek bulundu (p0.021 - p:0.019). Her iki grubun preoperatif (p0.094), postoperatif 1.gün (p0.091) ve postoperatif 3.gün (p0.095) white blood cell düzeyleri arasında istatistiksel olarak anlamlı bir fark saptanmadı. Tartışma: Kardiyo-pulmoner by-pass kullanılarak yapılan operasyonlarda inflamatuar yanıtın bir göstergesi olan tümör nekrozis faktör ve C-reaktif protein düzeyleri atan kalpte yapılanlara oranla anlamlı derecede yüksek bulunmuştur.Objective: In this study, tumor necrosis factor-α (TNF-α) and C-reactive protein (CRP) levels which are important in inflammatory response to off pump and on pump coronary by-pass surgery, were compared and their clinical reflections were examined. Study plan: Forty patients who underwent coronary artery by-pass grafting in our clinic, were included in the study. The first group included on-pump patients (Group I, n20) and second group included off pump patients (group II, n20). In both groups the day before surgery and post operative sixth hour of tumor necrosis factor, as well as the day before surgery, post operative first and third days of C - reactive protein levels were measured. Results: In the comparison of TNF- α levels, while the preoperative levels were not significantly different in both groups (p0.098), postoperative levels of Group 1 were significantly higher (p0.016). In both groups any significant difference between pre operative CRP levels (p0.074) was not found. In Group I, the first and third postoperative day CRP levels were significantly higher (p0.021-p0.019). White blood cell levels of each group at preoperative (p0.094), post operative 1st day (p0.091) and post operative 3rd day (p0.095) were not significantly different. Conclusion: As an indicator of inflammatory response, the tumor necrosis factor- α and Creactive protein levels were significantly higher in operations using cardiopulmonary by-pass than surgeries on beating hear
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Analysis of NPHS2 mutations in Turkish steroid-resistant nephrotic syndrome patients
Mutations in the NPHS2 gene are a frequent cause of familial and sporadic steroid-resistant nephrotic syndrome (SRNS). Inter-ethnic differences have also been suggested to affect the incidence of these mutations. The frequency and spectrum of podocin mutations in the Turkish population have remained largely unknown. As such, the aim of this study was to screen for podocin mutations in Turkish patients with SRNS. Thirty two patients from 30 unrelated families with SRNS were examined. There were seven familial cases from five different families and 25 sporadic cases. PCR-single-strand conformation polymorphism (SSCP) analysis of the NPHS2 gene was followed by direct sequencing. Five different NPHS2 mutations were detected in four of the 30 (13.3%) families studied; five familial patients from three unrelated families (60%) and one sporadic case (4%) were found to carry podocin mutations. The detected mutations included homozygous c. 419delG, compound heterozygous p. [Arg238Ser] + [Pro118Leu], homozygous p. [Pro20Leu; Arg168His] and heterozygous p. Pro20Leu. Two siblings with compound heterozygous mutations had been reported previously by our group. Podocin mutations were found to be responsible for some of the SRNS cases in Turkey, especially when there was more than one affected person in the family. Our results also suggest the presence of a wide range of phenotypic variability between individuals with the same genotype