281 research outputs found
An Approach for Rapid Assessment of Seismic Hazards in Turkey by Continuous GPS Data
The Earth is being monitored every day by all kinds of sensors. This leads an overflow of data in all branches of science nowadays, especially in Earth Sciences. Data storage and data processing are the problems to be solved by current technologies, as well as by those accessing and analyzing these large data sources. Once solutions have been created for collecting, storing and accessing data, then the challenge becomes how to effectively share data, applications and processing resources across many locations. The Global Positioning System (GPS) sensors are being used as geodetic instruments to precisely detect crustal motion in the Earth's surface. Rapid access to data provided by GPS sensors is becoming increasingly important for deformation monitoring and rapid hazard assessments. Today, reliable and fast collection and distribution of data is a challenge and advances in Internet technologies have made it easier to provide the needed data. This study describes a system which will be able to generate strain maps using data from continuous GPS stations for seismic hazard analysis. Strain rates are a key factor in seismic hazard analyses. Turkey is a country prone to earthquakes with a long history of seismic hazards and disasters. This situation has resulted in the studies by Earth scientists that focus on Turkey in order to improve their understanding of the Earth's crust structure and seismic hazards. Nevertheless, the construction of models, data access and analysis are often not fast as expected, but the combination of Internet technologies with continuous GPS sensors can be a solution to overcome this problem. This system would have the potential to answer many important questions to assess seismic hazards such as how much stretching, squashing and shearing is taking place in different parts of Turkey, and how do velocities change from place to place? Seismic hazard estimation is the most effective way to reduce earthquake losses. It is clear that reliability of data and on-line services will support the preparation of strategies for disaster management and planning to cope with hazards
Unusual causes of peritonitis in a peritoneal dialysis patient: Alcaligenes faecalis and Pantoea agglomerans
An 87 -year-old female who was undergoing peritoneal dialysis presented with peritonitis caused by Alcaligenes faecalis and Pantoea agglomerans in consecutive years. With the following report we discuss the importance of these unusual microorganisms in peritoneal dialysis patients
Procjena pouzdanosti triju indeksa za mjerenje hiperplazije gingive
Objectives: Numerous indices have been used to grade the severity of gingival overgrowth which led to suspicion regarding the results concerning its prevalence and pathogenicity. The aim of this study was to assess the concordance of three different gingival overgrowth indices, which were used widely in previous studies, and check their reliability and reproducibility. Material and Methods: A total of 30 full-mouth plaster casts and 90 intraoral photographs collected from 30 patients diagnosed with gingival overgrowth were included in our study. Three trained examiners performed measurements twice on plaster casts using gingival hyperplasia index (A index) and hyperplastic index (B index). Intraoral photographs were assessed also twice using (C index). Results: Concordance of intra-examiner and inter-examiner reliability of the recorded measurements was carried out for each index using weighted kappa (K), with a confidence interval of 95%. The A index revealed intra-examiner total kappa values between 0.724-0.876 for horizontal measurement and 0.512-0.823 for vertical measurement, and inter-examiner total kappa values between 0.255-0.626 horizontally and 0.235-0.279 vertically. The B index presented intra-examiner total kappa values between 0.587-0.868 horizontally and 0.653-0.855 vertically; and inter-examiner total kappa values between 0.393-0.595 and 0.372-0.635 for horizontal and vertical measurements, respectively. The C index achieved the highest intra-examiner concordance with total kappa values between 0.758-0.855 and inter-examiner total kappa values between 0.716-0.804. Conclusions: The C index evaluated through intraoral photographs is considered the most reliable and applicable method to be utilized. The C index is suggested to be used in large scale populations with its definite detailed criteria.Svrha istraživanja: Upotrijebljeni su brojni indeksi za ocjenjivanje stupnja hiperplazije gingive što je potaknulo sumnju u vezi s rezultatima o njezinoj prevalenciji i patogenosti. Cilj ovog istraživanja bio je procijeniti podudarnost triju različitih indeksa hiperplazije gingive koji su naširoko upotrebljavani u dosadašnjim istraživanjima te provjeriti njihovu pouzdanost i ponovljivost. Materijal i metode: U naše istraživanje uključeno je ukupno 30 sadrenih modela obiju čeljusti i 90 intraoralnih fotografija prikupljenih od 30 pacijenata s dijagnozom hiperplazije gingive. Tri educirana ispitivača dva su puta obavila mjerenja na sadrenim modelima koristeći se indeksom gingivne hiperplazije (indeks A) i hiperplastičnim indeksom (indeks B). Intraoralne fotografije također su procijenjene dva puta s pomoću indeksa C. Rezultati: Podudarnost zabilježenih mjerenja između ispitivača i unutar ispitivača analizirana je za svaki indeks s pomoću ponderiranog kappa testa (K) s intervalom pouzdanosti od 95 %. Indeks A pokazao je ukupne kappa vrijednosti između ispitivača između 0,724 i 0,876 za horizontalno mjerenje i 0,512 do 0,823 za vertikalno mjerenje, a ukupne kappa vrijednosti među ispitivačima bila je između 0,255 i 0,626 horizontalno i 0,235 do 0,279 vertikalno. Indeks B pokazivao je ukupne kappa vrijednosti unutar ispitivača između 0,587 i 0,868 horizontalno i 0,653 do 0,855 vertikalno i ukupne kappa vrijednosti među ispitivačima između 0,393 i 0,595 te 0,372 do 0,635 za horizontalna i vertikalna mjerenja. Indeks C postigao je najveću podudarnost između ispitivača s ukupnim kappa vrijednostima između 0,758 i 0,855 i ukupnim kappa vrijednostima između ispitivača između 0,716 i 0,804. Zaključci: Indeks C procijenjen putem intraoralnih fotografija smatra se najpouzdanijom i najprimjenjivijom metodom. Predlaže se za veće populacije zbog jasnih, detaljnih kriterija
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Estimates of Seismic Potential in the Marmara Sea Region from Block Models of Secular Deformation Constrained by Global Positioning System Measurements
We model the geodetically observed secular velocity field in northwestern Turkey with a block model that accounts for recoverable elastic-strain accumulation. The block model allows us to estimate internally consistent fault slip rates and locking depths. The northern strand of the North Anatolian fault zone (NAFZ) carries approximately four times as much right-lateral motion (∼24 mm/yr) as does the southern strand. In the Marmara Sea region, the data show strain accumulation to be highly localized. We find that a straight fault geometry with a shallow locking depth of 6-7 km fits the observed Global Positioning System velocities better than does a stepped fault geometry that follows the northern and eastern edges of the sea. This shallow locking depth suggests that the moment release associated with an earthquake on these faults should be smaller, by a factor of 2.3, than previously inferred assuming a locking depth of 15 km.Earth and Planetary Science
Solving a large-scale crew pairing problem
Due to copyright restrictions, the access to the full text of this article is only available via subscription.Airline companies seek to solve the problem of determining an assignment of crews to a pre-determined flight schedule with minimum total cost, called the Crew Pairing Problem (CPP). Most of the existing studies focus on the CPP of North American airlines, which widely differs from that of most European airline companies in terms of the objective function, the flight structure, and the planning horizon. In this study, we develop an optimizationdriven heuristic algorithm that can efficiently handle large-scale instances of the CPP that must be solved on a monthly basis. We perform computational experiments using flight schedules of an European airline company to test the performance of the solution method. Our computational results demonstrate that our algorithm is able to provide high-quality solutions to monthly instances with up to 27 000 flight legs.TÜBİTA
Study of Alternative GPS Network Meteorological Sensors in Taiwan: Case Studies of the Plum Rains and Typhoon Sinlaku
Plum rains and typhoons are important weather systems in the Taiwan region. They can cause huge economic losses, but they are also considered as important water resources as they strike Taiwan annually and fill the reservoirs around the island. There are many meteorological sensors available for investigating the characteristics of weather and climate systems. Recently, the use of GPS as an alternative meteorological sensor has become popular due to the catastrophic impact of global climate change. GPS provides meteorological parameters mainly from the atmosphere. Precise Point Positioning (PPP) is a proven algorithm that has attracted attention in GPS related studies. This study uses GPS measurements collected at more than fifty reference stations of the e-GPS network in Taiwan. The first data set was collected from June 1st 2008 to June 7th 2008, which corresponds to the middle of the plum rain season in Taiwan. The second data set was collected from September 11th to September 17th 2008 during the landfall of typhoon Sinlaku. The data processing strategy is to process the measurements collected at the reference stations of the e-GPS network using the PPP technique to estimate the zenith tropospheric delay (ZTD) values of the sites; thus, the correlations between the ZTD values and the variation of rainfall during the plum rains and typhoon are analyzed. In addition, several characteristics of the meteorological events are identified using spatial and temporal analyses of the ZTD values estimated with the GPS network PPP technique
Solving a Large-Scale Integrated Fleet Assignment and Crew Pairing Problem
Airline schedule planning problems are typically decomposed into smaller problems, which are solved in a sequential manner, due to the complexity of the overall problems. This results in suboptimal solutions as well as feasibility issues in the consecutive phases. In this study, we address the integrated fleet assignment and crew pairing problem (IFACPP) of a European Airline. The specific network and cost structures allow us to develop novel approaches to this integrated problem. We propose an optimization-driven algorithm that can efficiently handle large scale instances of the IFACPP. We perform a computational study on real-world monthly flight schedules to test the performance of our solution method. Based on the results on instances with up to 27,500 flight legs, we show that our algorithm provides solutions with significant cost savings over the sequential approach.Scopu
Unusual presentation of peritonitis with persistent clear aspirate: a case report
<p>Abstract</p> <p>Introduction</p> <p>Peritonitis is the most frequent complication of peritoneal dialysis. Diagnosis of peritonitis includes symptoms and signs of peritonitis with a cloudy aspirate of more than 100 WBC/ml, as well as positive cultures. Although sterile peritonitis has been reported in the literature, to the best of our knowledge this is the first report of an unusual presentation of peritonitis without any white blood cells in the peritoneal aspirate despite multiple positive peritoneal cultures.</p> <p>Case presentation</p> <p>An 82-year-old Caucasian man who had been on continuous cycling peritoneal dialysis for 12 years was admitted to our hospital with general malaise, loss of appetite, weight loss and somnolence. He did not describe abdominal pain or fever. Even though his peritoneal fluid was consistently negative for leukocytes and clear, he had peritonitis with different organisms consecutively.</p> <p>Conclusions</p> <p>Our case report shows that any patient on peritoneal dialysis presenting with evidence of infection (fever, peripheral leukocytosis) without an obvious cause should have aspirate cultures done even if the aspirate is clear and abdominal pain is absent. Our case report may change the initial work-up and management of these patients. We believe this report is of interest to general medicine and emergency room physicians as well as nephrologists.</p
Postseismic deformation following the Mw 7.2, 23October 2011 Van earthquake (Turkey): Evidence for a seismic fault reactivation
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