Partitioning de Bruijn Graphs into Fixed-Length Cycles for Robot Identification and Tracking

We propose a new camera-based method of robot identification, tracking and orientation estimation. The system utilises coloured lights mounted in a circle around each robot to create unique colour sequences that are observed by a camera. The number of robots that can be uniquely identified is limited by the number of colours available, $q$, the number of lights on each robot, $k$, and the number of consecutive lights the camera can see, $\ell$. For a given set of parameters, we would like to maximise the number of robots that we can use. We model this as a combinatorial problem and show that it is equivalent to finding the maximum number of disjoint $k$-cycles in the de Bruijn graph $\text{dB}(q,\ell)$. We provide several existence results that give the maximum number of cycles in $\text{dB}(q,\ell)$ in various cases. For example, we give an optimal solution when $k=q^{\ell-1}$. Another construction yields many cycles in larger de Bruijn graphs using cycles from smaller de Bruijn graphs: if $\text{dB}(q,\ell)$ can be partitioned into $k$-cycles, then $\text{dB}(q,\ell)$ can be partitioned into $tk$-cycles for any divisor $t$ of $k$. The methods used are based on finite field algebra and the combinatorics of words.Comment: 16 pages, 4 figures. Accepted for publication in Discrete Applied Mathematic

MEASUREMENT INVARIANCE: CONCEPT AND IMPLEMENTATION

An empirical evidence for independent samples of a population regarding measurement invariance implies that factor structure of a measurement tool is equal across these samples; in other words, it measures the intended psychological trait within the same structure. In this case, the evidence of construct validity would be strengthened within the frame of the scores obtained from the tool. When measurement invariance is not supported, the researchers should consider the possibility of the different factor designs for each group. Ignoring such a situation brings forward the probability about differentiation of the trait(s) measured by measurement tool for that/those group(s), so it causes to suspect the validity of the scores obtained from the tool. The aim of this study is to examine measurement invariance in the context of the conceptual foundations of multi-group confirmatory factor analysis, and discuss the subject through the results from two hypothetical data set that one supports measurement invariance, but the other does not. As a result of analysis performed in this direction, it is determined that the five-factor design derived from the first data set is equal across the groups in the majors of science, health, and social science. It is also concluded that the three-factor design obtained from the secondary data set is not equal for female and male groups. Besides, the exploratory factor analysis performed for female and male groups separately shows that the three-factor design of the tool is valid for females, but the number of factors was four in males. When the factor design for male group is examined, it is determined that the three items in the second factor separate significantly. That leads to the conclusion that it is crucial to test measurement invariance in studies regarding the determination of the psychometric properties of the tool.

MEASUREMENT INVARIANCE: CONCEPT AND IMPLEMENTATION

An empirical evidence for independent samples of a population regarding measurement invariance implies that factor structure of a measurement tool is equal across these samples; in other words, it measures the intended psychological trait within the same structure. In this case, the evidence of construct validity would be strengthened within the frame of the scores obtained from the tool. When measurement invariance is not supported, the researchers should consider the possibility of the different factor designs for each group. Ignoring such a situation brings forward the probability about differentiation of the trait(s) measured by measurement tool for that/those group(s), so it causes to suspect the validity of the scores obtained from the tool. The aim of this study is to examine measurement invariance in the context of the conceptual foundations of multi-group confirmatory factor analysis, and discuss the subject through the results from two hypothetical data set that one supports measurement invariance, but the other does not. As a result of analysis performed in this direction, it is determined that the five-factor design derived from the first data set is equal across the groups in the majors of science, health, and social science. It is also concluded that the three-factor design obtained from the secondary data set is not equal for female and male groups. Besides, the exploratory factor analysis performed for female and male groups separately shows that the three-factor design of the tool is valid for females, but the number of factors was four in males. When the factor design for male group is examined, it is determined that the three items in the second factor separate significantly. That leads to the conclusion that it is crucial to test measurement invariance in studies regarding the determination of the psychometric properties of the tool

Mapping functional traits: comparing abundance and presence-absence estimates at large spatial scales

Efforts to quantify the composition of biological communities increasingly focus on functional traits. The composition of communities in terms of traits can be summarized in several ways. Ecologists are beginning to map the geographic distribution of trait-based metrics from various sources of data, but the maps have not been tested against independent data. Using data for birds of the Western Hemisphere, we test for the first time the most commonly used method for mapping community trait composition – overlaying range maps, which assumes that the local abundance of a given species is unrelated to the traits in question – and three new methods that as well as the range maps include varying degrees of information about interspecific and geographic variation in abundance. For each method, and for four traits (body mass, generation length, migratory behaviour, diet) we calculated community-weighted mean of trait values, functional richness and functional divergence. The maps based on species ranges and limited abundance data were compared with independent data on community species composition from the American Christmas Bird Count (CBC) scheme coupled with data on traits. The correspondence with observed community composition at the CBC sites was mostly positive (62/73 correlations) but varied widely depending on the metric of community composition and method used (R2: 5.6×10−7 to 0.82, with a median of 0.12). Importantly, the commonly-used range-overlap method resulted in the best fit (21/22 correlations positive; R2: 0.004 to 0.8, with a median of 0.33). Given the paucity of data on the local abundance of species, overlaying range maps appears to be the best available method for estimating patterns of community composition, but the poor fit for some metrics suggests that local abundance data are urgently needed to allow more accurate estimates of the composition of communities

Çocuklar İçin Benlik Algısı Profilinin Uyarlanması ve Farklı Değişkenlere Göre Ölçme Değişmezliğinin Test Edilmesi

Bu araştırmanın amacı Çocuklar İçin Benlik Algısı Profilinin (ÇİBAP) uyarlanarak, farklı değişkenlere göre ölçme değişmezliğinin test edilmesidir. Bu amaçla Harter (1985) tarafından geliştirilen ve orijinal dili İngilizce olan ÇİBAP’ın 5-8. sınıf öğrencileri için uyarlaması yapılmış ve uyarlanan aracın beş faktörlü yapısının cinsiyet, sosyo-ekonomik düzey ve sınıf düzeylerine ait gruplar için eşitliği test edilmiştir. Tarama modelinde yürütülen araştırmada ön uygulama (n=320) ve asıl uygulama (n=1798) çerçevesinde veriler, iki çalışma grubundan elde edilmiştir. ÇİBAP’ın uyarlanması sürecinde, çeviriler tamamlandıktan sonra uzman görüşlerine başvurulmuş, geri çevirisi yapılmış ve aracın dilsel eşdeğerliliğinin sağlanıp sağlanamadığına ilişkin her iki dili de iyi bilen bir gruba uygulama yapılmıştır. Çevirinin dilsel eşdeğerlilik kanıtları sağlandıktan sonra aracın ön uygulaması yapılmıştır. Ön uygulamadan elde edilen veriler analiz edilmiş, psikometrik açıdan sorunu olan maddeler için alan uzmanlarının görüşlerine başvurulmuştur. Alan uzmanlarından ve ön uygulama sürecinde katılımcılardan alınan geribildirimler doğrultusunda, bazı maddeler yeniden gözden geçirilmiş ve böylece asıl form hazırlanmıştır. Ön ve asıl uygulamalardan elde edilen veri setleri üstünden geçerlilik çalışmaları için açımlayıcı ve doğrulayıcı faktör analizleri yapılmış, alt ölçekler arasındaki korelasyonlar ve madde test korelasyonları hesaplanmış; iç tutarlılık katsayılarını belirlemek amacıyla Cronbach alfa değerleri hesaplanmış ve son olarak asıl formun kararlılık katsayısını elde etmek amacıyla test-tekrar test yöntemi uygulanmıştır. ÇİBAP’ın faktör yapısının cinsiyet, SED ve sınıf grupları için eşitliğini belirlemek amacıyla çoklu-grup doğrulayıcı faktör analizleri yapılmıştır. Yapılan analizler sonucunda, aracın beş faktörlü yapısının söz konusu değişkenler açısından eşit olduğu, diğer bir ifadeyle ölçme değişmezliğinin sağlandığı sonucuna ulaşılmıştır

Effect of surface pre-Treatment and temperature on the adhesive strength of hybrid aluminum joints

The strength of adhesively bonded hybrid joints is affected by various factors which include type of assembly, type of adherend, operating temperature, surface pre-treatment and others. In this study, the effects of pre-treatment and operating temperature on bonding strength are investigated experimentally. The experiments are carried out under mechanical abrasion, FPL and P2 etching conditions at different test temperatures of -20°C, 0°C, 20°C, 50°C. Three type rivet arrangements are tested in order to see an effect of rivet reinforcement. Test results showed that FPL and P2 etching improved the strength of the joint according to mechanical abrasion. The strength of the joints did not change significantly depending on temperature and humidity for mechanical abrasion, but the acid etched joints are affected by temperature and humidity, especially P2 etched joints presented lower strength at 50°C and 95 % Rh. The reinforcement of the adhesive joint with rivets did not remarkably affect the joint strength

Lasting the distance: The survival of alien birds shipped to New Zealand in the 19th century

Invasive alien species are a major threat to biodiversity and human activities, providing a strong incentive to understand the processes by which alien invasion occurs. While it is important to understand the determinants of success at each of several invasion stages—transport, introduction, establishment, and spread—few studies have explored the first of these stages. Here, we quantify and analyze variation in the success of individual animals in surviving the transport stage, based on shipping records of European passerines destined for New Zealand. We mined the original documents of Acclimatisation Societies, established in New Zealand for the purpose of introducing supposedly beneficial alien species, in combination with recently digitized newspaper archives, to produce a unique dataset of 122 ships that carried passerines from Europe to New Zealand between 1850 and 1885. For 37 of these shipments, data on the survival of individual species were available. Using generalized linear mixed models, we explored how survival was related to characteristics of the shipments and the species. We show that species differed greatly in their survival, but none of the tested traits accounted for these differences. Yet, survival increased over time, which mirrors the switch from early haphazard shipments to larger organized shipments. Our results imply that it was the quality of care received by the birds that most affected success at this stage of the invasion process

What factors increase the vulnerability of native birds to the impacts of alien birds?

Biodiversity impacts caused by alien species can be severe, including those caused by alien birds. In order to protect native birds, we aimed to identify factors that influence their vulnerability to the impacts of alien birds. We first reviewed the literature to identify native bird species sustaining such impacts. We then assigned impact severity scores to each native bird species, depending on the severity of the impacts sustained, and performed two types of analyses. First, we used contingency table tests to examine the distribution of impacts across their severity, type and location, and across native bird orders. Second, we used mixed‐effects models to test factors hypothesised to influence the vulnerability of native birds to the impacts of alien birds. Ground‐nesting shorebirds and seabirds were more prone to impacts through predation, while cavity‐nesting woodpeckers and parrots were more prone to impacts through competition. Native bird species were more vulnerable when they occupied islands, warm regions, regions with climatic conditions similar to those in the native range of the invading alien species, and when they were physically smaller than the invading alien species. To a lesser extent, they were also vulnerable when they shared habitat preferences with the invading alien species. By considering the number and type of native bird species affected by alien birds, we demonstrate predation impacts to be more widespread than previously indicated, but also that damaging predation impacts may be underreported. We identify vulnerable orders of native birds, which may require conservation interventions; characteristics of native birds that increase their vulnerability, which may be used to inform risk assessments; and regions where native birds are most vulnerable, which may direct management interventions. The impacts sustained by native birds may be going unnoticed in many regions of the world: there is a clear need to identify and manage them

A PERSONAL PERFORMANCE EVALUATION IN MUNICIPALITIES: AN ANALYSIS OF IZMIR'S DISTRICT MUNICIPALITIES

Günümüzde kamu ve özel yönetim alanında çalışanların performansının değerlendirilmesi önemli bir konu olarak görülmektedir çünkü etkin bir performans değerlendirme sistemi üretilen iş veya hizmetin niteliğini de arttırmaktadır. Aynı olgu vatandaşların yaşam kalitesi açısından önemli hizmetler üreten belediyeler için de geçerlidir. Belediyeler genel olarak kamu yönetiminde geçerli olan personel değerlendirme sistemine tabidir. Bu sistemde memur statüsünce çalışanlar için öngörülen bir değerlendirme işlemi olmakla birlikte, sözleşmeli statüde ve işçi statüsünde çalışanlar için belirlenen standart bir yöntem bulunmamaktadır. Bu çalışmada performans değerlendirme ile ilgili temel teorik bilgiler ele alındıktan sonra, kamu personel rejimi için geçerli olan yapı tanıtılacaktır. Bunu takiben İzmir ili belediyelerinde yürütülen ve onların personele yönelik performans değerlendirme faaliyetlerini belirleme ve değerlendirme amacını güden bir alan araştırması kapsamında elde edilen bir takım veri ve bulgular belirtilerek değerlendirilecektir. Performance evaluation of workers in both public sector and private sector is seen as a significant case today because an effective performance evaluation system increases the quality of goods and services produced. Same concept is valid for the municipalities, which are serving tasks considerable in terms of citizen's quality of life. Municipalities are generally subject to the personnel evaluation system, which is current in public administration. In this system; there is a prescribed evaluation process for the officer personnel, but not a standard method decided for contracted staff or the worker personnel. In this study, the notional intelligence on performance evaluation will be discussed. Then, the structure in force for public servants regime will be introduced. Following that, the data and findings will be declared and examined which were achieved by a field survey based on the purpose of analyzing the performance evaluation activities towards personnel in municipalities of Izmi