315 research outputs found
Hyperbolic Spinor Representations of Non-Null Framed Curves
In this paper, we intend to bring together the hyperbolic spinors, which are
useful frameworks from mathematics to physics, and both spacelike and timelike
framed curves in Minkowski 3-space , which are new type
attractive frames and very crucial issue for singularity theory especially.
First, we obtain new adapted frames which are called adapted frames for
non-null (spacelike and timelike) framed curves in . Then, we
investigate the hyperbolic spinor representations of non-null framed curves of
the general and adapted frames. Also, we find some geometric results and
interpretations with respect to them, and we obtain illustrative and numerical
examples with figures in order to support the given theorems and results.Comment: 28 pages, 2 figure
Stochastig modeling with continuous feedback markov fluid queues
Cataloged from PDF version of article.Markov fluid queues (MFQ) are systems in which a continuous-time Markov chain
determines the net rate into (or out of ) a buffer. We deal with continuous feedback
MFQs (CFMFQ) for which the infinitesimal generator of the background process
and the drifts in each state are allowed to depend on the buffer level through continuous
functions. Explicit solutions of CFMFQs for a few special cases has been
reported, but usually numerical methods are preferred.
A numerically stable solution method based on ordered Schur decomposition
is already known for multi-regime MFQs (MRMFQ). We propose a framework for
approximating CFMFQs by MRMFQs via discretizing the buffer space. The parameters
of the CFMFQ are approximated by piecewise constant functions. Then, the
solution is obtained by block-tridiagonal LU decomposition for the related MRMFQ.
Moreover, we describe a numerical method that enables us to solve large scale systems
efficiently.
We model basically two different stochastic systems with CFMFQs. The first is
the workload-bounded MAP/PH/1 queue, to which the arrivals occur according to
a workload-dependent MAP (Markovian Arrival Process), and the arriving job size
distribution is phase-type. The jobs that would cause the buffer to overflow are rejected
partially or completely. Also, the service speed is allowed to depend on the
buffer level. As the second application, we model the horizon-based delayed reservation
mechanism in Optical Burst Switching networks with or without fiber delay
lines. We allow multiple traffic classes and the effect of offset-based and FDL-based
differentiation among traffic classes in terms of burst blocking is investigated.
Lastly, we propose a distributed algorithm for air-time fairness in multi-rate
WLANs that overcomes the performance anomaly in IEEE 802.11 WLANs. We also
give a stochastic model of the proposed model, and provide a novel and elaborate proof for its effectiveness. We also present an extensive simulation study.Yazıcı, Mehmet AkifPh.D
Synthesis, characterization and luminescence properties of long afterglow Phosphor Ba4Al14O25:Eu,Dy
Long persistent afterglow phosphor, Ba4Al14O25:Eu2+,Dy3+ was prepared at high temperature by a solid state reaction in a weak reductive atmosphere. The crystal structure of Ba4Al14O25:Eu2+,Dy3+ has been determined as an orthorhombic Pmmm space group with a=18.200(6) Å, b=16.923(6) Å, c=5.131(21) Å, V=1580.3(9) Å3 and Z=8. The reflectance measurement was obtained by using the Diffuse Reflectance Spectrophotometer and the band gap energy of the undoped host phase of Ba4Al14O25 was calculated by using Kubelka-Munk treatment on the diffuse reflectance spectra, and found to be 4.72 eV. The excitation and emission peaks are broad bands and the main emission peak at 520 nm with shoulder at 496 nm belongs to the intrinsic defect of the host and 4f65d1→4f7 transition of Eu2+, respectively. The afterglow decay curve implied that this phosphor contains fast and slow-decay processes. The thermoluminescence glow curve showed one dominant glow peak observed at 50 oC and two weak glow peaks at around 140 oC and 220 oC which are related to the defects at different trap depths
Bir köpekte gerçek hermafrodismus: Olgu sunumu
True hermaphroditism in a dog is described in this case report. An eight month old cross-breed dog with enlarged
structure protruding from the vulva was brought for an ovariohysterectomie operation. Physical examinations
exposed the presence of an os clitoris and urethral orifice at the base of the os clitoris. Exploratory laparotomy
was performed as a diagnostic and therapeutic procedure. Both gonadal tissues and the genital tract were removed
during surgery and brought to the laboratory for pathological examinations. Microscopic examinations showed
that the right gonad had both seminiferous tubules like testis and primer follicles like ovarium. The
concentrations of serum progesterone, testosterone and 17β-estradiol were 0,188 ng/ml, 1,008 ng/ml and 23,61
pg/ml respectively. We concluded that this is a true hermaphrodismus case due to the simultaneous presence of
two sex gonads.Bu çalışmada, gerçek hermafrodit bir köpek anlatılmıştır. Vulvasından dışarıya doğru çıkan büyük bir kitle olan 8
aylık melez bir köpek kısırlaştırma operasyonu için araştırma merkezimize getirildi. Fiziksel muayenelerde os
klitorisin varlığı ve bunun bazalinde uretral deliğin olduğu saptandı. Teşhis ve tedavi amacıyla hayvana
ovariohysterectomie operasyonu uygulandı. Her iki gonadal doku ve uterus patolojik incelemeler için laboratuvara
gönderildi. Mikroskobik incelemeler, sağ gonadın hem testis gibi seminifer tubuller hem de ovaryum gibi primer
foliküller içerdiğini gösterdi. Serum progesteron, 17β-östradiol ve testosteron düzeyleri sırasıyla 0,188 ng/ml,
23,61 pg/ml, 1,008 ng/ml olarak ölçüldü. Köpekte her iki gonadal dokunun aynı anda bulunması nedeniyle
olgunun bir gerçek hermafrodismus olgusu olduğu kanısına varıldı
The Mediator Role of Employee Voice in the Effect of Agile Leadership on Teachers’ Affective Occupational Commitment
The research aims to reveal the effect of teachers’ agile leadership perceptions on their affective occupational commitment
and how employee voice plays a mediating role in this effect. The study group of the research consists of 354 teachers
working in Istanbul in 2021. The research is carried out according to the relational survey model. Correlation analysis is
carried out and tested using the suggested mediation model based on the relationship between the variables to determine
the relationship between variables. According to the research findings, the agile leadership characteristics of school principals
positively affect their affective occupational commitment. Additionally, mediation analysis showed that employee voice is a
partial mediator between agile leadership characteristics and affective occupational commitment. This research contributes
to the theory by revealing the important effects of the agile leader in the school. In the light of the findings, the implications
of the agile leader, employee voice, and occupational commitment of teachers were discussed, and suggestions were made
for future research
Dosimetric phantom consistency of TMR-10 protocol in homogeneous and inhomogeneous regions in gamma knife radiosurgery planning
Introduction: The algorithms used in the GammaPlan treatment planning system are “Tissue Maximum Ratio (TMR) classical,”“TMR 10,” and “convolution” algorithms, respectively. In this study, the consistency of dosimetric measurements with the TMR 10 protocol used in SRC (stereotactic radiosurgery) planning in lesions located in homogeneous and inhomogeneous regions in different intracranial location scenarios was investigated. Methods: In this study, the accuracy of administration of multiple metastasis treatment on the Gamma Knife Perfexion device was investigated. Computed tomography was performed with 1 mm cross-section intervals of CIRS brand Atom randofantoma. Critical organs and three different brain metastases located in homogeneous and heterogeneous regions, which are not on the same plane with each other, were drawn on the phantom. Planned target volume (PTV) volumes were created without margining the drawn gross tumor volumes, and three separate plans were made for three different PTV volumes. All plans were calculated using the TMR 10 algorithm. Critical organ doses were kept below the brain-SRC criteria for all calculated plans. Gafchromic EBT-3 film was placed on the sections with the target volume drawn on the phantoms and irradiated (1600 cGy, 50% isodose area). Measurements were made three times. The measured film results and the doses calculated from the planning were compared with gamma index analysis for different tolerance values. Results: In our study, for three different lesions planned and irradiated with different gradient index values, a difference of 2.11–9.58% was observed between the values calculated with the TMR-10 protocol and the values obtained in the dosimet- ric measurement. A decrease in consistency was observed, especially in inhomogeneous region placements. Discussion and Conclusion: There may be inconsistency between the TMR-10 protocol and actual dosimetric measurements, especially around inhomogeneous intracranial structures. We hope that this inconsistency will decrease in the future with the developing dose calculation protocols
Near-field radiation from nano-particles and nano-antennas illuminated with a focused beam of light
The interaction of photons with metallic nanoparticles and nanoantennas yields large enhancement and tight localization of electromagnetic fields in the vicinity of nanoparticles. In the first part of this study, the interaction of a spherical nanoparticle with focused beams of various angular spectra is investigated. This study demonstrates that the focused light can be utilized to manipulate the near-field radiation around nanoparticles. In the second part of this study, the interaction between linearly and radially polarized focused light with prolate spheroidal nanoparticles and nano-antennas is investigated. Strong and tightly localized longitudinal components of a radially polarized focused beam can excite strong plasmon modes on elongated nanoparticles such as prolate spheroids. The effect of a focused beam on parameters such as the numerical aperture of a beam and the wavelength of incident light, as well as particle geometry and composition are also studied
Inferior vena cava and pulmonary artery diameters for prognosis of Coronavirus disease
Aim: In this study, we aimed to analyze the relationship between pulmonary artery (PA) and inferior vena cava (IVC) diameters in non-contrast chest computerized tomography (CT) images of patients with coronavirus disease 2019 (COVID-19) and overall survival.
Material and Methods: This retrospective study consisted of 404 consecutive patients who underwent chest CT after admission to the emergency department between May 1 and June 31. 2021. CT measurements were performed by two radiologists. The prognostic value of PA and IVC diameters, the computerized tomography severity score (CT-55), quick sequential organ failure assessment (qSOFA), and confusion, urea, respiratory rate, blood pressure, and age >= years (CURB-65) score on overall survival were examined.
Results: The median age of the participants was 62 years (49-72), and 196 (48.5%) were male. Of the 404 patients, 61 died after admission. While main-PA, left-PA, right-PA (p < 0.001) and NC-transverse (IVC-Tr) (p = 0.045) diameters were larger and statistically significant in the patients who died (AUC; 0.686, 0.722, 0.746, and 0.581, respectively), a statistically significant difference was not detected in terms of IVC anteroposterior diameter (IVC-AP) (p = 0.053) and the IVC-Tr/AP (p = 0.754) ratio. There was a statistical difference in mortality in ciSOFA, CURB-65, and CT-SS values (AUC; 0.727, 0.798, and 0.708 p < 0.001, respectively).
Discussion: PA diameters measured from chest CT images at admission (main-PA >= 26.5 mm, right-PA >= 22.9 mm, and left-PA >= 21.6 mm) and the IVC-Tr diameter (>= 34.5 mm) can be used as mortality predictors for COVID-19, along with other prognostic scores
Spor Köşe Yazılarında 4 Büyük Kulübün Olumlu-Olumsuz Kavramlarla Birlikte Anılma Durumları ve Kulüp İmajı
Kulüpler hakkındaki köşe yazılarının olumlu veya olumsuz olması, kulüplerin imajı ve geleceği açısından oldukça önemlidir. Bu durumun araştırılması amacıyla bu çalışmada, 4 büyük kulübün spor köşe yazılarında olumlu ve olumsuz kavramlarla birlikte anılma durumları ve bunların kulüp imajına etkileri ortaya konulmuştur. Tirajı en yüksek 5 gazeteden 52 spor köşe yazarına ait 2017-2021 yılları arasındaki yazılardan içeriğinde Fenerbahçe, Galatasaray, Beşiktaş ve Trabzonspor geçen 9862 köşe yazısıyla çalışma yürütülmüştür. İşlemlerin tamamında Doğal Dil İşleme teknikleri ve Visual Studio ortamında C# dilinde geliştirilen yazılımdan faydalanılmıştır. 42 alt kavrama sahip 19 olumlu üst kavram ile 62 alt kavrama sahip 23 olumsuz üst kavramın köşe yazılarında kulüplerle birlikte anılma durumları, geliştirilen yazılımla belirlenmiştir. Araştırma bulgularında 4 kulüple farklı sıralamalarda olsa da en çok vurgulanan 3 olumlu kavramın “saygı, dost, adalet”; en az vurgulananlarınsa bütün kulüplerde aynı sıralamada “merhamet, şefkat, kibar” olduğu görülmüştür. Öte yandan en çok/en az vurgulanan 3 olumsuz kavramdaysa kulüpten kulübe farklılık belirlenmiştir. Fenerbahçe’yle en çok “kavga, sinir, düşman”, en az “vahşi, argo, hile”; Galatasaray’la en çok “hakaret, kavga, düşman”, en az “argo, vahşi, kışkırt”; Beşiktaş ve Trabzonspor’la en çok “haksız, kavga, sinir”; Beşiktaş’la en az “argo, vahşi, holigan”; Trabzonspor’la en az “argo, kışkırt, vahşi” olumsuz kavramları birlikte anılmıştır. Bununla birlikte, köşe yazılarında olumlu kavramlara olumsuz kavramlardan daha fazla yer verildiği tespit edilmiştir. Olumlu kavramlarla daha sık anılan kulüplerin kurumsal imajının ve saygınlığının artabileceği; olumsuz kavramlarla daha çok anılan kulüplerinse zihinlerde olumsuz yer ederek kulüp imajına uzun yıllar zarar verebileceği değerlendirilmiştir
Ocena zaburzeń przewodzenia przedsionkowego i czynności mechanicznej lewego przedsionka u chorych z subklinicznymi zaburzeniami czynności tarczycy
Introduction: Changes of thyroid hormones levels may lead to effects, not only in ventricular function, but also atrial function. The aim
of this study was to investigate left atrial (LA) mechanical functions, atrial electromechanical coupling and P wave dispersion in patients
with subclinical thyroid disorders.
Material and methods: Eighty patients with subclinical thyroid disorders and forty controls were included. A diagnosis of subclinical
thyroid disorders were reached with increased or decreased serum TSH and normal free T4 (fT4) levels. LA volumes were measured
using the biplane area length method and LA active and passive emptying volumes and fraction were calculated. Intra- and interatrial
electromechanical delay were measured by tissue Doppler imaging (TDI).
Results: All groups had similar demographic findings. LA mechanical functions significantly impaired in subclinical thyroid disorders than control
group. Intra- and Interatrial delay, were measured significantly higher in patients with subclinical thyroid disorders than control group. PA lateral
and interatrial delay were positively correlated with TSH (r = 0.507, p = 0.006 and r = 0.455, p = 0.015, respectively) in subclinical hypothyroid patients.
There was negative correlation between TSH and interatrial delay (r = –0.492, p = 0.006) in subclinical hyperthyroid patients. Linear multivariate
regression analysis demonstrated that, TSH was the only an independent factor of interatrial delay in patients with subclinica tlhyroid disorders.
Conclusions: This study showed that impaired LA mechanical and electromechanical function in subclinical thyroid disorders. TSH was
an independent determinant of interatrial delay. Prolonged atrial electromechanical coupling time and impaired mechanical atrial functions
may be related to the increased incidence of arrhythmias.Wstęp: Zmiany stężeń hormonów tarczycy mogą wpływać nie tylko na czynność komór serca, ale również na czynność przedsionków.
Niniejsze badanie przeprowadzono w celu oceny czynności mechanicznej lewego przedsionka (LA), sprzężenia elektromechanicznego
i dyspersji załamka P u chorych z subklinicznymi zaburzeniami czynności tarczycy.
Materiał i metody: Do badania włączono 80 chorych z subklinicznymi zaburzeniami czynności tarczycy i 40 osób stanowiących grupę
kontrolną. Zaburzenia czynności tarczycy rozpoznawano na podstawie obniżonego lub podwyższonego stężenia TSH w surowicy
i prawidłowego stężenia wolnej T4 (fT4). Zmierzono objętości LA, posługując się dwupłaszczyznową metodą area-lenght (pole– wymiar
podłużny). Obliczono również objętości i frakcje aktywnego i biernego opróżniania LA. Do pomiaru opóźnienia przewodnictwa wewnątrzi
międzyprzedsionkowego zastosowano technikę doplera tkankowego.
Wyniki: Grupy nie różniły się pod względem charakterystyki demograficznej. W grupie z zaburzeniami czynności tarczycy mechaniczna
funkcja przedsionków była istotnie upośledzona w porównaniu z osobami z grupy kontrolnej. Opóźnienie przewodnictwa wewnątrzi
międzyprzedsionkowego stwierdzano istotnie częściej u osób z zaburzeniami czynności tarczycy. Stwierdzono dodatnią korelację miedzy
opóźnieniem elektromechanicznym (PA lateral) i opóźnieniem przewodzenia międzyprzedsionkowego a TSH (odpowiednio r = 0,507;
p = 0,006 i r = 0,455; p = 0,015) u osób z subkliniczną niedoczynnością tarczycy. Z kolei u osób z subkliniczną nadczynnością tarczycy
zaobserwowano ujemną korelację między TSH i opóźnieniem przewodzenia międzyprzedsionkowego (r = –0,492; p = 0,006). W wieloczynnikowej
analizie regresji liniowej wykazano, że stężenie TSH było jedynym parametrem niezależnie związanym z opóźnieniem
przewodzenia międzyprzedsionkowego u chorych z subklinicznymi zaburzeniami czynności tarczycy.
Wnioski: W niniejszym badaniu wykazano upośledzoną czynność mechaniczną i elektromechaniczną LA u chorych z subklinicznymi
zaburzeniami czynności tarczycy. Stężenie TSH było niezależnym czynnikiem determinującym opóźnienie przewodzenia międzyprzedsionkowego.
Wydłużenie czasu sprzężenia elektromechanicznego i upośledzenie mechanicznej czynności przedsionków mogą się wiązać
ze zwiększoną zapadalnością na zaburzenia rytmu
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