Procjena i liječenje otežanog dišnog puta kod pretilih bolesnica: retrospektivno istraživanje u jednom centru

The primary aim of this single center retrospective study was to evaluate difficult mask ventilation (DMV) and difficult laryngoscopy (DL) in a unique group of obese patients. A total of 427 adult patients with body mass index (BMI) ≥25 and surgically treated for endometrial cancer from 2011 to 2014 were assessed. Additional increase in BMI, comorbidities, bedside screening tests for risk factors, and the tools used to manage the patients were noted and their effects on DMV and/or DL investigated. Every escalation in the number of risk factors increased the probability of DMV 2.2-fold, DL 1.8-fold and DMV+DL 3.0-fold. Among bedside tests, limited neck movement (LNM), short neck (SN) and absence of teeth were significant for DMV (p25% were considered. In conclusion, LNM and SN are independent risk factors for developing DMV and/or DL in obese endometrial cancer patients, while BMI increase over 30 was not additionally affecting difficult airway.Primarni cilj ovoga retrospektivnog istraživanja provedenog u jednom centru bila je procjena otežane ventilacije maskom (OVM) i otežane laringoskopije (OL) u specifičnoj populaciji pretilih bolesnica. U istraživanje je bilo uključeno 427 odraslih bolesnica s indeksom tjelesne mase (ITM) >25 koje su kirurški liječene zbog karcinoma endometrija od 2011. Do 2014. godine. Dodatno su bilježeni utjecaj porasta ITM, pridruženih bolesti, čimbenika rizika određenih kliničkim probirnim testovima i alata kojim su se zbrinjavale bolesnice na OVM i/ili OL. Svaka eskalacija u broju rizičnih čimbenika je povećavala rizik OVM za 2,2 puta, OL 1,8 puta i OVM+OL 3,0 puta. Od kliničkih testova, ograničena pokretljivost vrata (OPV), kratak vrat (KV) i nedostatak zuba su bili značajni za OVM (p25, tada deseterostruki porast nije bio nezavisni rizični čimbenik. Zaključno, OPV i KV su nezavisni čimbenici rizika za razvoj OVM i/ili OL u pretilih bolesnica s karcinomom endmetrija, dok ITM veći od 30 nije dodatno uticao na otežani dišni put

ULUSLARARASI PETROL ÜRETİM REKABETİNİN OYUN TEORİSİ İLE ANALİZİ

Uluslararası ham petrol piyasasında oyuncuların OPEC (Petrol İhraç Eden Ülkeler Örgütü) üye ülkeleri ile OPEC’e üye olmayan petrol üreten ülkeler (non-OPEC) oldukları varsayımı yaygındır. Söz konusu oyuncuların kâr maksimizasyonu ve/veya petrol piyasalarını kontrol edebilme hedefiyle üretim seviyesi ve fiyat gibi çeşitli strateji kümeleri kullanarak rekabet eğilimine girmeleri söz konusu piyasanın oyun modelleri ile analiz edilebilirliğini ortaya koymaktadır. Bu çalışmanın amacı, OPEC ve non-OPEC ülkelerinin rekabete dayalı petrol üretim miktarlarını oyun teorisi temelinde analiz etmektir. Bu amaç doğrultusunda, oyunculara ait 1972-2019 dönemini kapsayan üretim miktarları ve ham petrol fiyat serileri kullanılmıştır. Petrol piyasalarındaki rekabetin varlığına işaret eden üretim fonksiyonlarına ait katsayılar Tam Bilgi En Küçük Kareler (FMOLS- Fully Modified Ordinary Least Square) yöntemi ile tahmin edilmiştir. Elde edilen modellerden Cournot-Nash ve Stackelberg denge çözümleri hesaplanmıştır. Cournot-Nash denge düzeyine göre Stackelberg denge düzeylerinde lider oyuncunun üretiminin artığı, takipçi oyuncunun üretim düzeyinin ise azaldığı görülmüştür. Bulgular Cournot-Nash denge çıktılarının Stackelberg denge çıktılarından daha yüksek olduğu çalışmalar ile paralellik göstermiştir. Oyuncuların üretim miktarı ve fiyat stratejileri vasıtasıyla optimum üretim düzeyine ulaşmaları için Cournot-Nash dengesinde kalmaları önerilmektedir

The NANOGrav 12.5-year data set: A computationally efficient eccentric binary search pipeline and constraints on an eccentric supermassive binary candidate in 3C 66B

The radio galaxy 3C 66B has been hypothesized to host a supermassive black hole binary (SMBHB) at its center based on electromagnetic observations. Its apparent 1.05-year period and low redshift ($\sim0.02$) make it an interesting testbed to search for low-frequency gravitational waves (GWs) using Pulsar Timing Array (PTA) experiments. This source has been subjected to multiple searches for continuous GWs from a circular SMBHB, resulting in progressively more stringent constraints on its GW amplitude and chirp mass. In this paper, we develop a pipeline for performing Bayesian targeted searches for eccentric SMBHBs in PTA data sets, and test its efficacy by applying it on simulated data sets with varying injected signal strengths. We also search for a realistic eccentric SMBHB source in 3C 66B using the NANOGrav 12.5-year data set employing PTA signal models containing Earth term-only as well as Earth+Pulsar term contributions using this pipeline. Due to limitations in our PTA signal model, we get meaningful results only when the initial eccentricity $e_0<0.5$ and the symmetric mass ratio $\eta>0.1$. We find no evidence for an eccentric SMBHB signal in our data, and therefore place 95% upper limits on the PTA signal amplitude of $88.1\pm3.7$ ns for the Earth term-only and $81.74\pm0.86$ ns for the Earth+Pulsar term searches for $e_00.1$. Similar 95% upper limits on the chirp mass are $(1.98 \pm 0.05) \times 10^9\,M_{\odot}$ and $(1.81 \pm 0.01) \times 10^9\,M_{\odot}$. These upper limits, while less stringent than those calculated from a circular binary search in the NANOGrav 12.5-year data set, are consistent with the SMBHB model of 3C 66B developed from electromagnetic observations.Comment: 27 Pages, 10 Figures, 1 Table, Accepted for publication in Ap

The NANOGrav 15-year Data Set: Bayesian Limits on Gravitational Waves from Individual Supermassive Black Hole Binaries

Evidence for a low-frequency stochastic gravitational wave background has recently been reported based on analyses of pulsar timing array data. The most likely source of such a background is a population of supermassive black hole binaries, the loudest of which may be individually detected in these datasets. Here we present the search for individual supermassive black hole binaries in the NANOGrav 15-year dataset. We introduce several new techniques, which enhance the efficiency and modeling accuracy of the analysis. The search uncovered weak evidence for two candidate signals, one with a gravitational-wave frequency of $\sim$4 nHz, and another at $\sim$170 nHz. The significance of the low-frequency candidate was greatly diminished when Hellings-Downs correlations were included in the background model. The high-frequency candidate was discounted due to the lack of a plausible host galaxy, the unlikely astrophysical prior odds of finding such a source, and since most of its support comes from a single pulsar with a commensurate binary period. Finding no compelling evidence for signals from individual binary systems, we place upper limits on the strain amplitude of gravitational waves emitted by such systems.Comment: 23 pages, 13 figures, 2 tables. Accepted for publication in Astrophysical Journal Letters as part of Focus on NANOGrav's 15-year Data Set and the Gravitational Wave Background. For questions or comments, please email [email protected]

The NANOGrav 12.5 yr Data Set: Search for Gravitational Wave Memory

We present the results of a Bayesian search for gravitational wave (GW) memory in the NANOGrav 12.5 yr data set. We find no convincing evidence for any gravitational wave memory signals in this data set. We find a Bayes factor of 2.8 in favor of a model that includes a memory signal and common spatially uncorrelated red noise (CURN) compared to a model including only a CURN. However, further investigation shows that a disproportionate amount of support for the memory signal comes from three dubious pulsars. Using a more flexible red-noise model in these pulsars reduces the Bayes factor to 1.3. Having found no compelling evidence, we go on to place upper limits on the strain amplitude of GW memory events as a function of sky location and event epoch. These upper limits are computed using a signal model that assumes the existence of a common, spatially uncorrelated red noise in addition to a GW memory signal. The median strain upper limit as a function of sky position is approximately 3.3 × 10−14. We also find that there are some differences in the upper limits as a function of sky position centered around PSR J0613−0200. This suggests that this pulsar has some excess noise that can be confounded with GW memory. Finally, the upper limits as a function of burst epoch continue to improve at later epochs. This improvement is attributable to the continued growth of the pulsar timing array

The NANOGrav 15-Year Data Set: Detector Characterization and Noise Budget

Pulsar timing arrays (PTAs) are galactic-scale gravitational wave detectors. Each individual arm, composed of a millisecond pulsar, a radio telescope, and a kiloparsecs-long path, differs in its properties but, in aggregate, can be used to extract low-frequency gravitational wave (GW) signals. We present a noise and sensitivity analysis to accompany the NANOGrav 15-year data release and associated papers, along with an in-depth introduction to PTA noise models. As a first step in our analysis, we characterize each individual pulsar data set with three types of white noise parameters and two red noise parameters. These parameters, along with the timing model and, particularly, a piecewise-constant model for the time-variable dispersion measure, determine the sensitivity curve over the low-frequency GW band we are searching. We tabulate information for all of the pulsars in this data release and present some representative sensitivity curves. We then combine the individual pulsar sensitivities using a signal-to-noise-ratio statistic to calculate the global sensitivity of the PTA to a stochastic background of GWs, obtaining a minimum noise characteristic strain of $7\times 10^{-15}$ at 5 nHz. A power law-integrated analysis shows rough agreement with the amplitudes recovered in NANOGrav's 15-year GW background analysis. While our phenomenological noise model does not model all known physical effects explicitly, it provides an accurate characterization of the noise in the data while preserving sensitivity to multiple classes of GW signals.Comment: 67 pages, 73 figures, 3 tables; published in Astrophysical Journal Letters as part of Focus on NANOGrav's 15-year Data Set and the Gravitational Wave Background. For questions or comments, please email [email protected]