Tidal stirring of Milky Way satellites: a simple picture with the integrated tidal force

Most of dwarf spheroidal galaxies in the Local Group were probably formed via environmental processes like the tidal interaction with the Milky Way. We study this process via N-body simulations of dwarf galaxies evolving on seven different orbits around the Galaxy. The dwarf galaxy is initially composed of a rotating stellar disk and a dark matter halo. Due to the action of tidal forces it loses mass and the disk gradually transforms into a spheroid while stellar motions become increasingly random. We measure the characteristic scale-length of the dwarf, its maximum circular velocity, mass, shape and kinematics as a function of the integrated tidal force along the orbit. The final properties of the evolved dwarfs are remarkably similar if the total tidal force they experienced was the same, independently of the actual size and eccentricity of the orbit.Comment: 5 pages, 2 figures, contribution to the proceedings of JENAM 2010 in Lisbon, Symposium 2 "Environment and the formation of galaxies: 30 years later", comments welcom

Unplanned Settlement of Fishing Village Belawan in Medan City, Indonesia

Fishermen’s settlements in Belawan Medan tend to form unplanned. Social interaction in this village becomes the basis for the establishment of an unplanned settlement. Qualitative method is used in this research. The society’s social condition in this village offers a challenge in analyzing social influence towards the establishment of the fishing village in Medan City. The purpose of this research is to find the form of the unplanned settlement that occurred. The results of this research will create a theoretical concept related to the forms of a coastal village. The objective of this research is to produce a theoretical concept regarding unplanned settlement which can be implicated in studying the unplanned settlements in developing countries.Keywords: socio; unplanned; fishing; villageISSN: 2398-4287© 2017. The Authors. Published for AMER ABRA by e-International Publishing House, Ltd., UK. This is an open access article under the CC BYNC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia

An appraisal of the prevention of mother-to-child transmission of hepatitis B virus health system in Nigeria

The study aimed to assess the strengths and weaknesses, opportunities and threats influencing the achievement of prevention of mother-to-child transmission of hepatitis B virus. It also sought to suggest recommendations to improve the current prevention of mother-to-child transmission of hepatitis B virus health system in Nigeria. A critical appraisal of the prevention of mother-to-child transmission of hepatitis B virus health system in Nigeria was conducted. The WHO health system framework was used to assess the prevention of mother-to-child transmission of hepatitis B virus system. Considering the recent call by the World Health Organization to eliminate hepatitis and the existence of a robust prevention of mother-to-child transmission of human immunodeficiency virus health system, the prevention of mother-to-child transmission of hepatitis B virus health system in Nigeria is riddled with numerous challenges. These range from a health worker crisis, poor leadership and governance, inadequate health information, medicines, vaccines and technologies and poor service delivery. Urgent action in the Nigerian prevention of mother-to-child transmission of hepatitis B virus health system is required if Nigeria is to achieve its goal of eliminating hepatitis by 2021

Portfolio optimization models for project valuation

This dissertation presents (i) a framework for selecting and managing a portfolio of risky multi-period projects, called Contingent Portfolio Programming (CPP), and (ii) an inverse optimization procedure that uses this framework to compute the value of a single project. The dissertation specifically examines a setting where the investor can invest both in private projects and securities in financial markets, but where the replication of project cash flows with securities is not necessarily possible. This setting is called a mixed asset portfolio selection (MAPS) setting. The valuation procedure is based on the concepts of breakeven selling and buying prices, which are obtained by first solving an optimization problem and then an inverse optimization problem. In the theoretical part of the dissertation, it is shown that breakeven prices are consistent valuation measures, exhibiting sequential consistency, consistency with contingent claims analysis (CCA), and sequential additivity. Due to consistency with CCA, the present approach can be regarded as a generalization of CCA to incomplete markets. It is also shown that, in some special cases, it is possible to derive simple calculation formulas for breakeven prices which do not require the use of inverse optimization. Further, it is proven that breakeven prices for a mean-variance investor converge towards the prices given by the Capital Asset Pricing Model (CAPM) as the investor's risk tolerance goes to infinity. The numerical experiments show that CPP is computationally feasible for relatively large portfolios both in terms of projects and states, and illustrate the basic phenomena that can be observed in a MAPS setting.reviewe

Comprehensive survey on quality of service provisioning approaches in cognitive radio networks : part one

Much interest in Cognitive Radio Networks (CRNs) has been raised recently by enabling unlicensed (secondary) users to utilize the unused portions of the licensed spectrum. CRN utilization of residual spectrum bands of Primary (licensed) Networks (PNs) must avoid harmful interference to the users of PNs and other overlapping CRNs. The coexisting of CRNs depends on four components: Spectrum Sensing, Spectrum Decision, Spectrum Sharing, and Spectrum Mobility. Various approaches have been proposed to improve Quality of Service (QoS) provisioning in CRNs within fluctuating spectrum availability. However, CRN implementation poses many technical challenges due to a sporadic usage of licensed spectrum bands, which will be increased after deploying CRNs. Unlike traditional surveys of CRNs, this paper addresses QoS provisioning approaches of CRN components and provides an up-to-date comprehensive survey of the recent improvement in these approaches. Major features of the open research challenges of each approach are investigated. Due to the extensive nature of the topic, this paper is the first part of the survey which investigates QoS approaches on spectrum sensing and decision components respectively. The remaining approaches of spectrum sharing and mobility components will be investigated in the next part

Identification as a deterrent for security enhancement in cognitive radio networks

Cognitive Radio Networks (CRNs) are prone to emerging coexistence security threats such as Primary User Emulation Attack (PUEA). Specifically, a malicious CRN may mimic licensees’ (Primary Users (PUs)) signal characteristics to force another CRN to vacate its channels thinking that PUs have returned. While existing schemes are promising to some extent on detecting PUEAs, they are not able to prevent the attacks. In this article, we propose a PUEA Deterrent (PUED) algorithm that can provide PUEAs' commission details: offender CRNs and attacks’ time and bandwidth. There are many similarities between PUED and Closed-Circuit Television (CCTV) in terms of: deterrence strategy, reason for use, surveillance characteristics, surveillance outcome, and operation site. According to the criminology literature, robust CCTV systems have shown a significant reduction in visible offences (e.g. vehicle theft), reducing crime rates by 80%. Similarly, PUED will contribute the same effectiveness in deterring PUEAs. Furthermore, providing PUEAs’ details will prevent the network’s cognitive engine from considering the attacks as real PUs, consequently avoiding devising unreliable spectrum models for the attacked channels. Extensive simulations show the effectiveness of the PUED algorithm in terms of improving CRNs’ performance

Effects of Age and Sampling Position on Wood Property Variations in Nigerian Grown Gmelina Arborea

Wood properties of plantation grown (Gmelina arborea Roxb.) were evaluated in this study. Eighteen trees from 3 age classes namely: 18, 28 and 36 years were sampled at the butt, 50% merchantable length ML and 90% ML, and were radially partitioned into inner wood, middle wood and outer wood, on the basis of distance from pith. Result obtained was analyzed using ANOVA at 5%level. Mean SG were 0.33 for age 18, 0.41 for 28 and 0.46 for the 36 year old Gmelina. While SG varied inconsistently in 18 year old Gmelina, it decreased significantly from butt to 90% ML in 28 and 36 year old trees. MOR ,MOE and MCS// decreased generally from base to top for all age classes except in 28 year old, where variation in MOE was inconsistent. All properties studied increased from inner wood to outer wood. Axial uniformity in strength properties ranged between 0.50 and 0.64, 0.65 and 0.73, and from 0.49 to 0.82 in MOR, MOE and MCS respectively. Radial uniformity index also ranged between 0.69 and 0.78 in MOR, 0.78 and 0.85 in MOE and between 0.76 and 0.80 in MCS. For all the properties studied, wood uniformity was best in 36 year Gmelina along the radial plane, while 18 year Gmelina had the best uniformity index along the axial plane. Effect of age was highly significant on strength properties and its variation patterns. In particular, there was about 44.8% increase in strength properties from 18 to 28 years and 19.1% increase from 28 to36 years. Woods of Gmelina arborea varied significantly along and across the bole, and should be treated as such in their conversion and utilization strategies

Longevity and developmental stability in the dung fly Sepsis cynipsea, as affected by the ectoparasitic mite, Pediculoides mesembrinae

This is the final version of the article. Available from [Oxford University Press via the DOI in this record.Fluctuating asymmetry (FA) is a widely employed measure of developmental stability. It has been found to increase with many stressors including parasite infection. Associations between parasites and FA may exist for several reasons in addition to parasites being the direct cause of increased FA. Developmentally stable individuals may have superior immune systems, and be less susceptible to parasite infection, and/or may be less exposed to parasites than developmentally unstable ones. Mites negatively impact host fitness in a number of insects, and if FA is a reflection of general genetic quality, as has been proposed, associations between mite number and FA are predicted. Potential relationships were investigated between an ectoparasitic mite, Pediculoides mesembrinae (Canestrini) (Phthiraptera: Menoponidae) and FA in the common dung fly Sepsis cynipsea (L.) (Diptera: Sepsidae). While it was found that mite infested flies died much faster than flies without mites, indicating that mites indeed stress their hosts, counter to expectations, no associations between mites and FA were found in any analyses. Additionally, FA in mite-infected flies generally did not differ from previously published FA data from uninfected S. cynipsea. Nevertheless, parasitized males tended to be somewhat less asymmetrical than non-parasitized males, but based on our data, it does not appear that mite infestation is generally associated with developmental stability in S. cynipsea.We thank Hansueli Ochs, Bundesamt für Veterinärwesen BVET, Switzerland, for identification of the mites and for information on their behaviour and habits and Marco Demont for kindly supplying mites for the experimental infection experiment. Thanks also to Thomas Gut and Regina Schwilch for help measuring flies and counting mites, John Hunt and numerous other colleagues for discussion, and to the SNF, ESF and NERC for financial support