Principal response curves technique for the analysis of multivariate biomonitoring time series

Although chemical and biological monitoring is often used to evaluate the quality of surface waters for regulatory purposes and/or to evaluate environmental status and trends, the resulting biological and chemical data sets are large and difficult to evaluate. Multivariate techniques have long been used to analyse complex data sets. This paper discusses the methods currently in use and introduces the principal response curves method, which overcomes the problem of cluttered graphical results representation that is a great drawback of most conventional methods. To illustrate this, two example data sets are analysed using two ordination techniques, principal component analysis and principal response curves. Whereas PCA results in a difficult-to-interpret diagram, principal response curves related methods are able to show changes in community composition in a diagram that is easy to read. The principal response curves method is used to show trends over time with an internal reference (overall mean or reference year) or external reference (e.g. preferred water quality or reference site). Advantages and disadvantages of both methods are discussed and illustrate

Exoten

Een aanzienlijk deel van de macrofauna op harde substraten bestaat uit exoten. Dat kan problemen opleveren bij de beoordeling voor de Kaderrichtlijn Water. Ook onder de vissen komen exoten voor, maar slechts in kleine aantalle

First records of Dreissena rostriformis bugensis (Andrusov 1897) in the Meuse River

info:eu-repo/semantics/publishe

Show your best self(ie):An exploratory study on selfie-related motivations and behavior in emerging adulthood

Although self-presentation has been studied for decades, social networking sites (SNS) such as Facebook have produced novel opportunities for visual online self-presentation. Posting selfies is currently a popular mode of consciously constructing visual online self-presentations, yet most prior research is limited to selfie-posting alone. This study aimed to profile selfie-makers’ motivations and behavior, and examine the extent to which underlying mechanisms preceding selfie-posting are interconnected. Results of a survey (N = 224; 79.9% females; Mage = 21.66, SDage = 2.08) regarding selfie-behavior on SNS (e.g., Facebook and Instagram) characterized selfie-makers in emerging adulthood as mainly concerned with the social aspects of selfies. Entertainment and moment-retention were identified as main motivations for selfie-making. Findings supported the proposed Selfie-Stadium Model, representing various steps of selfie-taking and underlying motives as well as selection and editing before actual posting. This study on profiling selfie-makers and their self-presentation taps into a fairly new media use research domain

Me, My Selfie, and I:The Relations Between Selfie Behaviors, Body Image, Self-Objectification, and Self-Esteem in Young Women

Due to the enormous popularity of social networking sites (SNSs), online and offline social lives seem inextricably linked, which raises concerns for how SNS use relates to psychological health. Similarly, the omnipresence of selfies on SNSs-a form of appearance-related exposure-raises concerns regarding psychological health. This study aimed to investigate the relationships between body image, self-objectification, self-esteem, and various selfie behaviors among young women (N = 179). We hypothesized that a worsened body image (i.e., higher body dissatisfaction or lower body appreciation), higher levels of self-objectification, and lower self-esteem would precede greater engagement in selfie behaviors. Structural equation modeling showed that body appreciation is associated with greater engagement in selfie selection and deliberate posting, and that self-objectification is related to greater engagement in all selfie behaviors assessed. In support of our proposed model, a reversed model was also tested that showed poorer results. These findings suggest that body image may serve not only as an outcome of SNS use but also as a motive preceding selfie behaviors

An Axi-Symmetric Segmented Composite SKA Dish Design: Performance and Production Analysis

A concept of an axi-symmetric dish as antenna reflector for the next generation radio telescope - the Square Kilometre Array (SKA) - is presented. The reflector is based on the use of novel thermoplastic composite material (reinforced with carbon fibre) in the context of the telescope design with wide band single pixel feeds. The baseline of this design represents an array of 100's to 1000's reflector antennas of 15-m diameter and covers frequencies from <1 to 10 GHz. The purpose of our study is the analysis of the production cost of the dish and its performance in combination with a realistic wideband feed (such as the 'Eleven Antenna' feed) over a wide frequency band and a range of elevation angles. The presented initial simulation results inidicate the potential of the proposed dish concept for low-cost and mass production and demonstrate sensitivity comparable to that of the presently considered off-set Gregorian reflector antenna with the same projected aperture area. We expect this observation to be independent of the choice of the feed, as several other single-pixel wideband feeds (that have been reported in the literature) have similar beamwidth and phase center location, both being rather constant with frequency.Comment: Invited paper for the Asia-Pacific Microwave Conference 2011 (APMC 2011), Melbourne, 5-8 Dec., Australia, 201

Hemispheric Imaging of Galactic Neutral Hydrogen with a Phased Array Antenna System

Abstract The thousand element array (THEA) system is a phased array system consisting of 1 m 2 tiles having 64 Vivaldi elements each arranged on a regular 8-by-8 grid, which has been developed as a demonstrator of technology and applicability for SKA. In this paper we present imaging results of galactic neutral hydrogen with THEA. Measurements have been taken using a dense 2-by-2 array of four tiles as a four tile adder. The results are compared with results from the Leiden-Dwingeloo Survey, showing qualitative agreement, but also indicating that further studies are needed on the instrumental characteristics

Beamforming techniques for large-n aperture arrays

Beamforming is central to the processing function of all phased arrays and becomes particularly challenging with a large number of antenna element (e.g. >100,000). The ability to beamform efficiently with reasonable power requirements is discussed in this paper. Whilst the most appropriate beamforming technology will change over time due to semiconductor and processing developments, we present a hierarchical structure which is technology agnostic and describe both Radio-Frequency (RF) and digital hierarchical beamforming approaches. We present implementations of both RF and digital beamforming systems on two antenna array demonstrators, namely the Electronic Multi Beam Radio Astronomy ConcEpt (EMBRACE) and the dual-polarisation all-digital array (2-PAD). This paper will compare and contrast both digital and analogue implementations without considering the deep system design of these arrays.peer-reviewe