346 research outputs found
Classification and Spectral Evolution of Outbursts of Aql X-1
We present a broad classification of all outbursts detected with the All-Sky
Monitor (ASM) on the Rossi X-Ray Timing Explorer (RXTE) and the Monitor of All
Sky X-Ray Image (MAXI) of Aql X-1. We identify three types of outbursts;
long-high, medium-low, and short-low, based on the duration and maximum flux.
We analyse the trends in the "phase-space" of flux-derivative versus flux to
demonstrate the differences in the three identified outburst types. We present
a spectral analysis of the observations of Aql X-1 performed by the
Proportional Counter Array (PCA) onboard RXTE during the 2000 and 2011
outbursts of the long-high class and the 2010 outburst of the medium-low class.
We model the source spectrum with a hybrid thermal/non-thermal hot plasma
emission model (EQPAIR in XSPEC, Coppi 2000) together with a Gaussian component
to model the Fe K_alpha emission line. We construct time histories of the
source flux, the optical depth of the corona (tau), the seed photon temperature
(kT_bb) and the hard state compactness (l_h) for these three outbursts. We show
that the physical parameters of either classes reach the same values throughout
the outbursts, the only difference being the maximum flux. We discuss our
results in the terms of modes of interaction of the star with the disc and size
of the disc kept hot by irradiation. We conclude that irradiation is the
dominant physical process leading to the different classes of outbursts.Comment: MNRAS accepted. 12 pages, 9 figures, 3 table
The impact of the migration on the economic development and international trade
Labor is one of the production factors in the Economics and in the International Trade Theory. According to the theoreticians Labor was condisdered immobile in the international trade, and therefore Labor-rich countries had a comparative advantage in manufacturing and trading the labor-intensive products. After the Versailles Treaty in 1919, ILO has been established and developed the Principles of Rights at Work , which was the first step to protection of Labor Rights. In the middle of 20th Century, industrialized countries with the Labor deficiency started inviting the workers from less developed countries. This approach opened the Migration of the workers from lessdeveloped and developing countries to industrialized countries. Although the Migration stem from the economic, political, social and cultural reasons from the archaic centuries, however today’s migration based on similar reasons creates positive impacts on the economic development and international trade. The immigrants earn higher wages with the new jobs at the host countries, even they develop further investment projects in the host countries and the original countries. With the help of Migration both countries’ people reach up to a higher level of welfare, and the Balance of Payment deficits of both countries are being improved. The impact of Migration is not only economic, but also world peace and friendship among the folks are being improved, too
Simultaneous use of Individual and Joint Regularization Terms in Compressive Sensing: Joint Reconstruction of Multi-Channel Multi-Contrast MRI Acquisitions
Purpose: A time-efficient strategy to acquire high-quality multi-contrast
images is to reconstruct undersampled data with joint regularization terms that
leverage common information across contrasts. However, these terms can cause
leakage of uncommon features among contrasts, compromising diagnostic utility.
The goal of this study is to develop a compressive sensing method for
multi-channel multi-contrast magnetic resonance imaging (MRI) that optimally
utilizes shared information while preventing feature leakage.
Theory: Joint regularization terms group sparsity and colour total variation
are used to exploit common features across images while individual sparsity and
total variation are also used to prevent leakage of distinct features across
contrasts. The multi-channel multi-contrast reconstruction problem is solved
via a fast algorithm based on Alternating Direction Method of Multipliers.
Methods: The proposed method is compared against using only individual and
only joint regularization terms in reconstruction. Comparisons were performed
on single-channel simulated and multi-channel in-vivo datasets in terms of
reconstruction quality and neuroradiologist reader scores.
Results: The proposed method demonstrates rapid convergence and improved
image quality for both simulated and in-vivo datasets. Furthermore, while
reconstructions that solely use joint regularization terms are prone to
leakage-of-features, the proposed method reliably avoids leakage via
simultaneous use of joint and individual terms.
Conclusion: The proposed compressive sensing method performs fast
reconstruction of multi-channel multi-contrast MRI data with improved image
quality. It offers reliability against feature leakage in joint
reconstructions, thereby holding great promise for clinical use.Comment: 13 pages, 13 figures. Submitted for possible publicatio
Marketing Seafood Products in Marmara Sea: A Case Study Along The Coastal Strip in İstanbul Province
Marmara denizi; palamut, lüfer vb balıkların göç yolların in merkezinde olduğu için özel bir karaktere sahiptir. İstanbul İli ise yoğun nüfusu ile iş, turizm, kültür vb konularında ülkenin merkezi olması nedeniyle balık tüketiminin fazla olduğu bir bölgedir. Marmara denizinde avlanan balığın çok büyük bolü mü İstanbul'da satışa sunulmaktadır. Bu nedenle İstanbul Su Ürünleri Hali Türkiye'nin su ürünleri piyasasında belirleyici rol oynayan en büyük hali niteliğindedir. Bilindiği gibi tüm deniz ürünlerinin avlanma sonrası çabuk bozulabilmeözelliği nedeniyle en kısa ve etkin pazarlama kanalının seçilmesi büyük önem taşımaktadır. Bu araştırmanın temel amacı, deniz ürünleri pazarlamasının genel ya pisin ı ortaya koymaktır. Tüketiciler karides, kalkan ve lüfer gibi su ürünlerine yüksek bedel ödeyebilmektedirler, Ancak balıkçılar, aralarında yeterli ve etkin bir örgütlenme sağlayamadıklarından komisyoncu, perakendeci vb gibi uzun pazarlama kanallarını kullanmak durumunda kalmaktadırlar. Bu d urum tüketicilerin deniz ürünlerine ödedikleri bedelin ancak %20 kadarının balıkçıya dönebilmesine olanak tanımaktadır. Gerek üretici balıkçı ve gerekse tüketici için en yararlı modelin kooperatifleşme olduğu öngörülmektedir.Marmara sea has a special characteristics due to migration route ofvery delicious and valuable fish species such as Atlantic bonito, Blue fish etc. Fish consumption is high a mount in the Province of Istanbul where the centra I region of the business, tourism, culture, etc. because of the dense of population .The vast majority offish caught in the Marmara Sea is supplied forsale in Istanbul. Bu nedenle istanbul Su Urunleri Hali Türkiye'nin su ürünleri piyasasinda belirleyici roloynayan en büyükhali niteliğindedir. For this reason, Istanbul Seafood market is the biggest one that pi ays a decisive role in Turkey's seafood product market. Seafood products could be rapidly spoiled after fishing activities and so should be marketing as soon as possible to the consumers. The shortest and effective marketing channel should be chosen for marketing due to mentioned reason. The main objective of this research, is to determine thegeneralstructureof marketing seafood products in Istanbul Province. The consumers pay higher prices such as shrimp, turbot,bluefish etc. Unless because of i n adequate cooperation between fisherman, they could not get satisfactory income. Mediators play important role and according to the calculations about marketing margins they could get only out of 20% of final price paid by the customers. Cooperative is considered the most useful model for Formun Üstüboth producers and consumers
Palaeotethys-related sediments of the Karaburun Peninsula, western Turkey: constraints on provenance and stratigraphy from detrital zircon geochronology
Detrital zircon U–Pb geochronology of 15 Late Palaeozoic to Early Mesozoic siliciclastic sandstones from the Karaburun Peninsula in western Turkey determines maximum sedimentation ages, identifies possible source areas, and anchors the study area within the Palaeotethyan realm. Siliciclastic sandstones yielded ages from Triassic to Archean with major input from Palaeozoic to Neoproterozoic sources and very few Mesoproterozoic zircons. The youngest age groups set the new limit of the maximum depositional ages to Late Carboniferous–Early Permian for the Küçükbahçe and Dikendağı formations. Detrital zircons from Triassic sandstones are mainly Neoproterozoic and Palaeozoic in age. Zircons from the Scythian–Anisian Gerence Formation are predominantly Devonian and Carboniferous in age, while also Permian and Triassic zircon grains occur in the Carnian–Rhaetian Güvercinlik Formation. According to the zircon age populations and the data available from possible source regions, the Karaburun siliciclastic sediments, with the exception of two samples from the Dikendağı Formation, record sediment supply from units located at the southern margin of Eurasia during Late Palaeozoic and Early Mesozoic times. This interpretation is in agreement with palaeotectonic reconstructions for the closely related Greek islands of Chios and Inousses. The presence of Devonian accompanied by Carboniferous zircons in some of the Karaburun samples reveals similarities with Karakaya Complex sandstones of the Sakarya Zone in NW Turkey
Evolution of the Palaeotethys in the Eastern Mediterranean: A multi-method approach to unravel the age, provenance and tectonic setting of the Upper Palaeozoic Konya Complex and its Mesozoic cover sequence (south-central Turkey)
Thirteen siliciclastic sediments from the Upper Palaeozoic Konya Complex and its Mesozoic cover were studied by a multi-method approach combining thin-section petrography, bulk-rock geochemistry, mineral chemistry of rutile, and U–Pb geochronology of detrital zircons. Provenance sensitive data of samples from the Upper Palaeozoic Halıcı Formation indicate sediment supply from mainly low- to medium-grade metamorphosed sedimentary rocks of felsic character, while contribution from volcanic rocks was rare. The detrital zircon record of sediments from the Halıcı Formation documents sediment supply from different sources and excludes a similar provenance. Some samples show great similarities with Palaeozoic sandstones from the cover sequence of the Saharan Metacraton and the Arabian–Nubian Shield, while the other samples indicate a provenance that must be sought in units with a southern Eurasian affinity. The upper limit for sediment deposition in the Halıcı Formation is mostly constrained by Early Palaeozoic zircon populations, however, sediment accumulation in Pennsylvanian–Cisuralian time is more likely, contemporaneously with the Upper Palaeozoic succession on the Karaburun Peninsula (western Turkey). The provenance of sediments from the Upper Triassic Ardıçlı Formation remains enigmatic, but the source should be sought nonetheless in units close to the depositional site. In any case, detrital zircon age spectra and compositional data exclude recycling of underlying rock units (i.e. Halıcı Formation). Overall, our new provenance data reveal great similarities between the Konya Complex and comparable units (Chios, Karaburun) but also highlight distinct differences in terms of sediment composition and provenance
Group-invariant solutions of a nonlinear acoustics model
Based on a recent classification of subalgebras of the symmetry algebra of
the Zabolotskaya-Khokhlov equation, all similarity reductions of this equation
into ordinary differential equations are obtained. Large classes of
group-invariant solutions of the equation are also determined, and some
properties of the reduced equations and exact solutions are discussed.Comment: 14 page
Functional use change in green spaces: a case study of Kırklareli province
Green spaces which are one of the most important public spaces in urban design have an important role on qualified daily urban life. People escape from intense work pressure and traffic jam of metropoles to those urban green areas to take a breath even they cover a small size. In time, people's expectations from green spaces as functional and quantitative needs are changing. This change occurs due to increasing population and as the character of the urban life. This study examines the functional use and quantitative change of urban green spaces of Kirklareli Province from past to present. Kirklareli is a border city to Bulgaria which is located in north-west part of Turkey and this gives a transitional and a multicultural character to the city. The population is about 67360. In the course of time; green space needs have increased by the increasing population. In addition to this, green spaces' functional use change has been identified. According to the results of the study; from the aspect of the green space standards, Kirklareli found above standards with 17.5 m(2) per capita, but on the other hand, sport and playground areas found insufficient. The Oldest and the newest city plans of Kirklareli (1940s and 2012s cadastral plans) have been compared and site surveys implemented as the methodology. In site survey, current green spaces' functional uses as sport or playground are observed and determined and also current quantitative measure of the green spaces are verified. Urban green spaces in Kirklareli Province evaluated through considering world's most populated urban green space standards and Turkey's standards. This study utilizes to compose a substructure of the urban green space. Determined deficiencies and inadequacies of green spaces and functional needs in this study, can guide to further studies and implementations of Kirklareli Municipality.Publisher versio
Provenance and tectonic setting of Carboniferous–Triassic sandstones from the Karaburun Peninsula, western Turkey: A multi-method approach with implications for the Palaeotethys evolution
Carboniferous–Triassic siliciclastic sediments of the Karaburun Peninsula in western Turkey were studied to unravel their provenance and the tectonic setting of depositional basins within the Palaeotethyan realm. A set of complementary techniques including petrography, bulk-rock geochemistry and single-grain analysis of rutile, garnet and chrome spinel were applied to provide a diverse dataset for testing existing palaeotectonic models using both, established and recently published diagrams. We show that tectonic discrimination diagrams of siliciclastic sediments based on major and trace element whole-rock geochemical data do yield ambiguous results and are only partly in accordance with regional geological events. Chondrite-normalised REE patterns of Upper Palaeozoic samples are characterised by enrichment of LREE and a flat trend towards HREE. The degree of fractionation allows for discrimination between sandstones of Karaburun (LaN/YbN = 8.00–14.79) and adjacent Greek islands of Chios (5.82–9.23) and Inousses (7.40–9.95). Petrographic observations and compositional data from single-grain analysis indicate significant supply from low- to medium-grade metamorphic rocks of generally felsic character and minor input of (ultra)mafic detritus. Detrital chrome spinels in the Lower Triassic Gerence Formation are different in composition and shape compared to chrome spinels in Carboniferous–Permian sandstones. They were derived from a very proximal source and exhibit variable, but generally high Cr- and Mg-numbers, consistent with chrome spinels from podiform chromitites that have been formed in an intra-oceanic back-arc setting above a supra-subduction zone. We conclude that most of the Carboniferous–Triassic successions were deposited along the southern active margin of Eurasia in a continental-arc environment during the time period when Palaeotethys diminished in size and finally vanished. Large volumes of detritus were probably derived from rock units located in the present-day Balkan region and the Sakarya Zone, or equivalent successions that are not present anymore
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