384 research outputs found

    Extension of Nikiforov-Uvarov Method for the Solution of Heun Equation

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    We report an alternative method to solve second order differential equations which have at most four singular points. This method is developed by changing the degrees of the polynomials in the basic equation of Nikiforov-Uvarov (NU) method. This is called extended NU method for this paper. The eigenvalue solutions of Heun equation and confluent Heun equation are obtained via extended NU method. Some quantum mechanical problems such as Coulomb problem on a 3-sphere, two Coulombically repelling electrons on a sphere and hyperbolic double-well potential are investigated by this method

    Interferometer measurements of terahertz waves from Bi2Sr2CaCu2O8+d mesas

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    We fabricated rectangular mesa structures of superconducting Bi2Sr2CaCu2O8+d (Bi2212) using e-beam lithography and Ar ion beam etching techniques for terahertz (THz) emission. c-axis resistance versus temperature (R–T), current–voltage (I–V) characteristics and bolometric THz power measurements were performed to characterize Bi2212 mesas. The emission frequency of mesas was determined using a Michelson interferometer setup which also demonstrates polarized emission. Interference patterns of THz radiation from Bi2212 mesas were detected by various detectors such as a liquid helium cooled silicon composite bolometer, a Golay cell and a pyroelectric detector. An emitted power as high as 0.06 mW was detected from Bi2212 mesas. For the first time, most of the pumped power was extracted as THz emission from a Bi2212 mesa. The radiation at 0.54 THz was detected using the Michelson interferometric setup

    Interrelationship between the variability of Northern Hemispheric total ozone, temperature and eddy heat flux

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    Toplam ozonun en yoğun olarak bulunduğu 15km ile 55 km arasındaki orta atmosfer, dinamik etkilerin de en fazla görüldüğü bölgedir. Brewer-Dobson sirkülasyonu, orta atmosferdeki ozon taşınımını etkileyen temel çevrimdir. Girdap ısı akısı, Brewer-Dobson sirkülasyonu olarak da bilinen, kalan sirkülasyonun, düşey bileşenidir ve dinamik bir bakış için kullanılan rezidüel ortalama teorinin temelini oluşturmaktadır. Bu çalışmada, toplam ozon değişiminin orta atmosferdeki sıcaklık ve girdap ısı akısı ile etkileşimi dinamik olarak incelenmiştir. Brewer-Dobson sirkülasyonunun matematiksel olarak modellenmesinde, dönüştürülmüş Eulerian ortalama akış denklemlerinden yararlanılmıştır. Çalışmada sirkulasyonun hesaplanmasında 1998-2007 yılları arasındaki ECMWF-ERA- Interim re-analiz verilerinden, toplam ozon değerleri için ise TOMS, OMI uydu verileri ile ECMWF ozon karışma oranı verilerinden yararlanılmıştır. 1998-2007 yılları arasında Kuzey yarıküre ozon değişimleri incelendiğinde, yukarı orta enlemlerde ve kutup bölgesinde ozon miktarının tropiklerden daha fazla olduğu görülmüştür. Orta ve yukarı enlemlerdeki toplam ozonun değişmini de etkileyen birincil mekanizma olan sirkülasyonun, yıl içinde en kuvvetli olduğu dönem Ocak ayı, etkilerinin en az görüldüğü dönem ise Temmuz ayıdır. Gözönüne alınan periyotta toplam ozon değeri ortalama olarak tropiklerde 240DU değerinden kutup bölgelerinde 420 DU değerine kadar değişmektedir. Orta enlemlerde ise 260-360DU arasında değişmektedir. Planeter aktivitenin değişiminin en fazla görüldüğü 100mb seviyesi için orta enlemlerdeki toplam ozonla, sıcaklıklar arasında yakın bir ilişki elde edilmiştir. Benzer şekilde, tropiklerdeki girdap ısı akısının orta enlemlerdeki sıcaklıkları, orta enlemlerdeki girdap ısı akısının da kutuplardaki sıcaklıları kontrol ettiği görülmüştür. Anahtar Kelimeler: Stratosferik ozon, Brewer-Dobson sirkülasyonu, ozon azalması.Ozone levels in the atmosphere have significantly decreased over the last three decades not only over Polar Regions but also over mid-latitudes. This finding led to an intense debate on the characteristics of the stratospheric dynamics and atmospheric transport. Since most of the atmospheric ozone is found in the stratosphere and the vertical motion in the stratosphere is quite slow so the dynamics in this layer becomes of great significance to our climate. Evidently dynamical changes in the circulation contribute to observe ozone trends at northern mid-latitudes. Total ozone trends have been directly connected to changes in various dynamical parameters such as temperature, so thus eddy heat flux. The eddy heat flux is the product of meridional wind departures and temperature departures. Dynamically eddy heat flux is the vertical component of Brewer-Dobson circulation. Brewer-Dobson circulation which is also known as residual circulation has a strong influence on stratospheric ozone variability and transport processes. Brewer-Dobson circulation is very strong during winter (January) and it increases the total ozone over high latitudes. In summer (July) the circulation is weak. The global distribution of atmospheric heat transport is supported by zonally averaged parameters namely eddy heat flux and temperature. Since eddy heat flux transports heat, it has been obtained that dynamical temperature change is highly affected by the eddy heat flux. Physically temperature and eddy heat flux are strongly related to each other. Evidently the strong correlation between eddy heat flux and temperature interprets a relationship between total ozone and pronounced parameters. Dynamical features of Northern Hemispheric ozone transport, temperature and eddy heat flux and their relationships for the specified time interval (1998-2007) makes up the basics of the study. The dynamical processes produced by eddies or wave motion in the stratosphere and mesosphere give rise to the meridional circulation in the middle atmosphere that closely balances the force caused by the temperature deviation from the radiative equilibrium. Dynamic features affecting ozone include especially the atmospheric transport temperature variability and changes in eddy heat flux. Ozone transport and variability of eddy heat flux and temperature are defined by zonally averaged parameters. It is easier to examine atmospheric variability through zonal mean fields which is also mathematically less complicated than using 3 dimensional flow equations.. In order to view the residual atmospheric circulation and describe zonally averaged structure of the atmosphere, a mathematical formalism is used for the eddy-mean flow cancellation which provides a separation between eddies and the mean meridional circulation. The formulation defines the transformed Eulerian mean (TEM) or residual circulation. Residual circulation calculation is given by the sum of the Eulerian mean circulation components and the eddy terms. In the study eddy heat flux and temperature are separately processed to be linked with total ozone transport. In the present research total ozone data from Total Ozone Mapping Spectrometer (TOMS) (1998-2004), Ozone Monitoring Instrument (OMI) (2005-2007) and European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim Re-Analysis data (1998-2207) have been used. The selected period for Northern Hemisphere and 180°W- 180°E is compiled for the middle atmosphere which includes the region from 100mb in the lower stratosphere and up to 10mb in the stratosphere. Middle atmosphere is a dynamically driven region compared to the troposphere, which is more sensitive to thermal driven heat engine. Relationship between mid-latitudinal ozone, eddy heat flux and temperature is chosen as the starting point to create an emphasis on the area around this region. It is confirmed that tropical eddy heat flux highly controls the mid-latitudinal total ozone and mid-latitudinal lower stratospheric temperature. Additionally polar ozone is strongly affected by polar eddy heat flux. Eddy heat flux at the mid-latitudes is highly correlated with the polar temperatures.  Keywords: Stratospheric ozone, Brewer-Dobson circulation, ozone depletion

    Cholesteatoma of the concha bullosa: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Cholesteatoma is a relatively common disease within the middle ear cavity, but rarely it manifests in the paranasal sinuses. There is, to the best of our knowledge, only one other published case of cholesteatoma inside the concha bullosa in the English language literature.</p> <p>Case presentation</p> <p>An 81-year-old Caucasian woman was admitted to our hospital complaining of nasal obstruction, headache and diplopia. After endoscopic and radiological evaluation a transnasal endoscopic approach was chosen. The diagnosis of cholesteatoma was established by histopathological evaluation of the mass inside the concha bullosa.</p> <p>Conclusion</p> <p>Although it is rarely seen, cholesteatoma should be considered in the differential diagnosis of slow-growing and destructive paranasal masses.</p

    Corticosteroid-Refractory Myositis After Dual BRAF and MEK Inhibition in a Patient with BRAF V600E-Mutant Metastatic Intrahepatic Cholangiocarcinoma

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    Intrahepatic cholangiocarcinoma is a rare malignancy, which is rich in actionable alterations. Genomic aberrations in the mitogen-activated protein kinase (MAPK) pathway are common, an

    Initial load-to-failure and failure analysis in single- and double-row repair techniques for rotator cuff repair

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    This experimental study aimed to compare the load-to-failure rate and stiffness of single- versus double-row suture techniques for repairing rotator cuff lesions using two different suture materials. Additionally, the mode of failure of each repair was evaluated. In 32 sheep shoulders, a standardized tear of the infraspinatus tendon was created. Then, n = 8 specimen were randomized to four repair methods: (1) Double-row Anchor Ethibond(A (R)) coupled with polyester sutures, USP No. 2; (2) Double-Row Anchor HiFi(A (R)) with polyblend polyethylene sutures, USP No. 2; (3) Single-Row Anchor Ethibond(A (R)) coupled with braided polyester sutures, USP No. 2; and (4) Single-Row Anchor HiFi(A (R)) with braided polyblend polyethylene sutures, USP No. 2. Arthroscopic Mason-Allen stitches were placed (single-row) and combined with medial horizontal mattress stitches (double-row). All specimens were loaded to failure at a constant displacement rate on a material testing machine. Group 4 showed lowest load-to-failure result with 155.7 +/- A 31.1 N compared to group 1 (293.4 +/- A 16.1 N) and group 2 (397.7 +/- A 7.4 N) (P < 0.001). Stiffness was highest in group 2 (162 +/- A 7.3 N/mm) and lowest in group 4 (84.4 +/- A 19.9 mm) (P < 0.001). In group 4, the main cause of failure was due to the suture cutting through the tendon (n = 6), a failure case observed in only n = 1 specimen in group 2 (P < 0.001). A double-row technique combined with arthroscopic Mason-Allen/horizontal mattress stitches provides high initial failure strength and may minimize the risk of the polyethylene sutures cutting through the tendon in rotator cuff repair when a single load force is used

    Genetics and genetic counseling: Practices and opinions of primary care physicians in Turkey

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    PURPOSE: The purpose of this study was to assess the educational needs of physicians relating to genetics and genetic counseling in the Denizli region of Turkey. METHODS: Data were collected by questionnaire about physicians' approaches to genetics and genetic counseling. RESULTS: A total of 60 (60.0%) of 100 physicians working in Denizli province returned a questionnaire. Physicians described "their most knowledgeable subjects" in basic genetic information as chromosome abnormalities (41.8%), in genetic disorders as xeroderma pigmentosum (80.0%), and in genetic counseling as directing the parents of and couples with a risk for having a child affected by a genetic disease to an expert or a genetic counseling center (94.8%). Only 20.7% knew the ethical regulations and techniques related to genetic counseling. Physicians thought that they did not have sufficient knowledge about genetics or genetic counseling, and 83.9% would like to attend an educational course. CONCLUSIONS: As a result of this study, a genetics course is planned for physicians so they can actively participate in the prevention and early diagnosis of genetic diseases. ©2007The American College of Medical Genetics

    Exchange rate volatility and capital inflows: role of financial development

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    There is vast literature examining the impact of exchange rate volatility on various macroeconomic aggregates such as economic growth, trade flows, domestic investment, and more recently capital flows. However, these studies have ignored the role of financial development while examining the impact of exchange rate volatility on capital flows. This study aims to analyze the impact of exchange rate volatility on capital inflows towards developing countries by incorporating the role of financial development over the time period 1980–2013. In this regard, the behavior of two types of capital flows is examined: physical capital inflows measured as foreign direct investment, and financial inflows quantified through remittance inflows. The empirical investigation comprises the direct as well as indirect effect of exchange rate volatility on capital inflows. The study employs dynamic system GMM estimation technique to empirically estimate the effect of exchange rate volatility on capital inflows. The empirical results of the study identify that exchange rate volatility dampens both physical and financial inflows towards developing countries. The indirect impact of exchange rate volatility through financial development, however, turns out positive and statistically significant. This finding reflects that financial development helps in reduc- ing the harmful impact of exchange rate volatility on capital inflows. Hence, the study concludes that a developed financial system is an important channel through which developing countries may improve capital inflows in the long run.info:eu-repo/semantics/publishedVersio

    Laryngoscopic Examination During the COVID-19 Pandemic: Turkish Voice Speech and Swallowing Disorders Society and Turkish Professional Voice Society Recommendations

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    COVID-19 is highly transmissible and spreads rapidly in the population. This increases the occupational risk for health care workers. In otolaryngology clinic practice, patients with upper respiratory tract infection symptoms are common. Also, routine head and neck examinations such as oral cavity examination, nasal/nasopharyngeal examination, or video laryngostroboscopic evaluation are highly risky because of the aerosol formation. To emphasize this issue, two leading otolaryngology organizations in Turkey; 'Voice Speech and Swallowing Disorders Society', and 'Professional Voice Society' gathered a task force. This task force aimed to prepare a consensus report that would provide practical recommendations of the safety measurements during routine clinical care of laryngology patients. To fulfill this, universal aim, on the 2nd and 9th of May 2020, two web-based meetings were conducted by 20 expert physicians. This eighteen items list was prepared as an output
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