The role of space in the security and defence policy of Turkey. A change in outlook: Security in space versus security from space

Space and security domains are strongly related with each other. Nowadays, space is an indispensable part of security and defence policy, and it is increasingly becoming a critical infrastructure for strategic Command, Control, Communications, Computers, Intelligence, Surveillance and Reconnaissance (C4ISR) systems. However, space is vulnerable itself to the new space threats. This study reviews the current and near future space role in Turkey's security and defence policy and aims to address the threats against space based capabilities. To provide security from space, space based systems shall themselves need to be secure in space to warrant the security. The concept of security from space starts with space security, in other words the security in space. This paper also highlights the emerging technological opportunities for these space threats to be secure in space in order to provide the security from space. According to the relevant taxonomy, a categorized opportunity proposal for more robust and resilient space/satellite projects' architecture is proposed for Turkey

Using lexical chains for keyword extraction

Cataloged from PDF version of article.Keywords can be considered as condensed versions of documents and short forms of their summaries. In this paper, the problem of automatic extraction of keywords from documents is treated as a supervised learning task. A lexical chain holds a set of semantically related words of a text and it can be said that a lexical chain represents the semantic content of a portion of the text. Although lexical chains have been extensively used in text summarization, their usage for keyword extraction problem has not been fully investigated. In this paper, a keyword extraction technique that uses lexical chains is described, and encouraging results are obtained. (C) 2007 Elsevier Ltd. All rights reserved

Improved of Approximating Function Li(x)

Let pi(x) be the prime-counting function that gives the number of primes less than or equal to x, for any positive number x and let the approximating function Li(x) denote the off set integral logarithm of x. This function is a good approximation to the number of prime numbers less than x. We propose a simple modification of Li(x) gauss prediction function for reduces of pi(x)-Li(x)

Using lexical chains for keyword extraction

Keywords can be considered as condensed versions of documents and short forms of their summaries. In this paper, the problem of automatic extraction of keywords from documents is treated as a supervised learning task. A lexical chain holds a set of semantically related words of a text and it can be said that a lexical chain represents the semantic content of a portion of the text. Although lexical chains have been extensively used in text summarization, their usage for keyword extraction problem has not been fully investigated. In this paper, a keyword extraction technique that uses lexical chains is described, and encouraging results are obtained. © 2007 Elsevier Ltd. All rights reserved

Lexical cohesion based topic modeling for summarization

In this paper, we attack the problem of forming extracts for text summarization. Forming extracts involves selecting the most representative and significant sentences from the text. Our method takes advantage of the lexical cohesion structure in the text in order to evaluate significance of sentences. Lexical chains have been used in summarization research to analyze the lexical cohesion structure and represent topics in a text. Our algorithm represents topics by sets of co-located lexical chains to take advantage of more lexical cohesion clues. Our algorithm segments the text with respect to each topic and finds the most important topic segments. Our summarization algorithm has achieved better results, compared to some other lexical chain based algorithms. © 2008 Springer-Verlag Berlin Heidelberg

Planetary migration in evolving planetesimals discs

In the current paper, we further improved the model for the migration of planets introduced in Del Popolo et al. (2001) and extended to time-dependent planetesimal accretion disks in Del Popolo and Eksi (2002). In the current study, the assumption of Del Popolo and Eksi (2002), that the surface density in planetesimals is proportional to that of gas, is released. In order to obtain the evolution of planetesimal density, we use a method developed in Stepinski and Valageas (1997) which is able to simultaneously follow the evolution of gas and solid particles for up to 10^7 yrs. Then, the disk model is coupled to migration model introduced in Del Popolo et al. (2001) in order to obtain the migration rate of the planet in the planetesimal. We find that the properties of solids known to exist in protoplanetary systems, together with reasonable density profiles for the disk, lead to a characteristic radius in the range 0.03-0.2 AU for the final semi-major axis of the giant planet.Comment: IJMP A in prin

Iron abundance distribution in the hot gas of merging galaxy clusters

We present XMM-Newton/EPIC observations of six merging galaxy clusters and study the distributions of their temperature, iron (Fe) abundance and pseudo-entropy along the merging axis. For the first time, we focus simultaneously, and in a comprehensive way, on the chemical and thermodynamic properties of the freshly collided intracluster medium (ICM). The Fe distribution of these clusters along the merging axis is found to be in good agreement with the azimuthally-averaged Fe abundance profile in typical non-cool-core clusters out to $r_{500}$. In addition to showing a moderate central abundance peak, though less pronounced than in relaxed systems, the Fe abundance flattens at large radii towards $\sim$0.2-0.3 $Z_\odot$. Although this shallow metal distribution is in line with the idea that disturbed, non-cool-core clusters originate from the merging of relaxed, cool-core clusters, we find that in some cases, remnants of metal-rich and low entropy cool cores can persist after major mergers. While we obtain a mild anti-correlation between the Fe abundance and the pseudo-entropy in the (lower entropy, $K$ = 200-500 keV cm$^2$) inner regions, no clear correlation is found at (higher entropy, $K$ = 500-2300 keV cm$^2$) outer radii. The apparent spatial abundance uniformity that we find at large radii is difficult to explain through an efficient mixing of freshly injected metals, particularly in systems for which the time since the merger is short. Instead, our results provide important additional evidence in favour of the early enrichment scenario - in which the bulk of the metals are released outside galaxies at $z$ > 2-3 - and extend it from cool-core and (moderate) non-cool-core clusters to a few of the most disturbed merging clusters as well. These results constitute a first step towards a deeper understanding of the chemical history of merging clusters.Comment: Accepted for publication in A&A, 21 pages with 17 figures and 19 table

Assessment of Soluble Urokinase-Type Plasminogen Activator Receptor (supAR) in Chronic Obstructive Pulmonary Disease

Background: Chronic obstructive pulmonary disease (COPD) is a disease characterized by a progressive airflow limitation. Soluble urokinase-type plasminogen activator receptor (suPAR) is released from the membrane-bound plasminogen activator, and is positively correlated with the activation of immune system.Aims: Release of inflammatory mediators is increased in chronic obstructive pulmonary disease (COPD), particularly during exacerbations. The objective of this study was to compare plasma levels of suPAR and serum levels of C-reactive protein (CRP) during exacerbation and stable periods in patients with COPD.Study Design: Prospective clinical study. Methods: The patients with COPD were divided into 3 groups for evaluations: those with stable COPD [SCOPD] (n= 54), pre-treatment acute exacerbation COPD [AECOPD] (n= 53), and post-treatment AECOPD (n= 52). Plasma suPARand serum CRP levels were assessed for each patient.Results: Whereas the increased serum CRP levels of the participants were 54.82±56.63 mg/l during acute exacerbation period, during the stable period it was 5.02±6.31 mg/l and statistically significant (p= 0.0001). The suPAR level was 1.28±0.52ng/ml during the acute exacerbation period vs.1.21±0.59ng/ml during the stable period, without a difference (p= 0.49). There was a statistically significant decrease in the CRP serum levels; yet, although not statistically significant  a remarkable decrease was seen in the suPAR levels obtained before and after the management of exacerbations (p= 0.001 and p= 0.06 respectively).Conclusion: These results support the idea that suPAR, a novel biomarker, might be an important indicator if verified with further prospective studies in evaluating COPD exacerbations and treatment response like CRP used for decades

Heme-protein vibrational couplings in cytochrome c provide a dynamic link that connects the heme-iron and the protein surface

The active site of cytochrome c (Cyt c) consists of a heme covalently linked to a pentapeptide segment (Cys-X-X-Cys-His), which provides a link between the heme and the protein surface, where the redox partners of Cyt c bind. To elucidate the vibrational properties of heme c, nuclear resonance vibrational spectroscopy (NRVS) measurements were performed on 57Fe-labeled ferric Hydrogenobacter thermophilus cytochrome c 552, including 13C8-heme-, 13C 515N-Met-, and 13C15N-polypeptide (pp)-labeled samples, revealing heme-based vibrational modes in the 200- to 450-cm-1 spectral region. Simulations of the NRVS spectra of H. thermophilus cytochrome c552 allowed for a complete assignment of the Fe vibrational spectrum of the protein-bound heme, as well as the quantitative determination of the amount of mixing between local heme vibrations and pp modes from the Cys-X-XCys-His motif. These results provide the basis to propose that heme-pp vibrational dynamic couplings play a role in electron transfer (ET) by coupling vibrations of the heme directly to vibrations of the pp at the protein - protein interface. This could allow for the direct transduction of the thermal (vibrational) energy from the protein surface to the heme that is released on protein/protein complex formation, or it could modulate the heme vibrations in the protein/protein complex to minimize reorganization energy. Both mechanisms lower energy barriers for ET. Notably, the conformation of the distal Met side chain is fine-tuned in the protein to localize heme-pp mixed vibrations within the 250-to 400-cm-1 spectral region. These findings point to a particular orientation of the distal Met that maximizes ET