Neutron Star Structure from Electromagnetic and Gravitational Wave Observations

Neutron star (NS) research primarily relied on spectral observations before the first gravitational wave (GW) detection from the binary neutron star merger was done by the LIGO-VIRGO collaboration. The GW170817 merger event provided mass and tidal deformability Λ˜ constraints for neutron stars. This project used these constraints and associated them with the constraints made by the NS X-ray observations to construct neutron star models. Selective X-ray sources were used in this work, which showed reliable uncertainties from their previous uses. The mass-radius constraints from the electromagnetic (EM) observations were constructed from seven quiescent low-mass X-ray binaries (QLMXBs), three photospheric radius expansion X-ray busters (PREs), and the NICER observation of PSR J0030+451. Also, two different neutron star equation of state (EOS) priors, three polytropes (3P) and four line-segment (4L), were used for the analyses. The radial constraints of a 1.4 M⇐ NS from the combined dataset with GW, QLMXBs, and PREs were R1.4 ∈ [11.21 km,12.55 km] and R1.4 ∈ [11.25 km, 12.39 km] for the 3P and 4L EOS priors, respectively. Adding the NICER observation to the other data did not improve these constraints but shifted slightly towards the larger radii. Two models were constructed by convolution operations on EM data, named intrinsic scattering (IS), to test unknown uncertainties in them. No significant variations were found from these IS analyses. This project also compared several nearly EOS independent quantities of neutron star binary parameters with the model posteriors. Also, the Pearson correlation tests were done to check radial dependencies of the slope of the symmetry energy L and the minimum value of the maximum mass neutron star M_max. These tests showed that M_max is always independent of R, but the correlation between L and R depends on the EOS prior

Hierarchical Design Based Intrusion Detection System For Wireless Ad hoc Network

In recent years, wireless ad hoc sensor network becomes popular both in civil and military jobs. However, security is one of the significant challenges for sensor network because of their deployment in open and unprotected environment. As cryptographic mechanism is not enough to protect sensor network from external attacks, intrusion detection system needs to be introduced. Though intrusion prevention mechanism is one of the major and efficient methods against attacks, but there might be some attacks for which prevention method is not known. Besides preventing the system from some known attacks, intrusion detection system gather necessary information related to attack technique and help in the development of intrusion prevention system. In addition to reviewing the present attacks available in wireless sensor network this paper examines the current efforts to intrusion detection system against wireless sensor network. In this paper we propose a hierarchical architectural design based intrusion detection system that fits the current demands and restrictions of wireless ad hoc sensor network. In this proposed intrusion detection system architecture we followed clustering mechanism to build a four level hierarchical network which enhances network scalability to large geographical area and use both anomaly and misuse detection techniques for intrusion detection. We introduce policy based detection mechanism as well as intrusion response together with GSM cell concept for intrusion detection architecture.Comment: 16 pages, International Journal of Network Security & Its Applications (IJNSA), Vol.2, No.3, July 2010. arXiv admin note: text overlap with arXiv:1111.1933 by other author

Stock Price Reaction to Dividend Announcement: the Case of Bangladesh Capital Market

Stock price response towards the ‘dividend announcement’ is highly supported both by theoretically and empirically. Investors consider several factors in investing funds in any particular securities of capital market of which the most important factor is the return from the investment in securities that typically depends on the dividend declaration. Company declares dividend in the form of cash and/ or stock with in the financial year (quarterly or biannually) to meet the expectations of investors considering the ability and strategy of the company. In this paper, a thorough investigation is done with the help of ‘event study methodology’ to analyze the effect of dividend announcement on stock prices taking seventy four listed companies of Dhaka Stock Exchange (DSE) in Bangladesh. The study finds that dividend declaration does not bring any gain to the investors; rather they lose due to substantial fall in share prices both in pre dividend and post dividend period as market passes through regular and continuous revision of directives of regulators to check a bullish market. It is expected that the study will not only help in developing investors’ awareness regarding stock price sensitivity towards dividend declaration, but also help to design their investment decision in a more rational, efficient and convenient way to protect their interest. Furthermore, it will help the companies to determine their good standing, aware investors in affluently designing their investment decision, and regulators, the prime policy makers, to take necessary initiatives for the betterment of all concerned. Keywords: Dividend, Capital Market, Securities, SEC, Bangladesh

Supply Chain Management of Textile Industry: A Case Study on Bangladesh

This study addresses a descriptive study on the current scenario of Textile industry in Bangladesh. This paper demonstrates above mentioned scenario in terms of supply chain management (SCM). The textile industry, an important segment in Bangladeshs manufacturing industry, play a critical role in its economic development. The textile sector fulfils almost cent percent domestic demand apart from the fulfilling the external demand of clothing and apparels to a large extent in Bangladesh. The Textile industry is a long chain including raw materials production, complement production, clothing production and so on. SCM concept is made possible as a conventional management tool for all manufactures are to strive to improve their product quality, to reduce their product and service cost and to shorten their product delivery and response time in a highly competitive market. This research developed based on the secondary data, including online databases, journals, review papers, etc. The effective SCM of textile industry include lower inventories, lower costs, higher productivity, greater productivity, greater agility shorter lead times, higher profits and greater customer loyalty. This paper encompasses the constraints of textile industry in Bangladesh, including ineffective communication, invisibility of SCM, long lead time, etc. which would unlock further research to develop this sector