Cosmological perturbations in coherent oscillating scalar field models

The fact that fast oscillating homogeneous scalar fields behave as perfect fluids in average and their intrinsic isotropy have made these models very fruitful in cosmology. In this work we will analyse the perturbations dynamics in these theories assuming general power law potentials V(ϕ) = λ|ϕ|^n /n. At leading order in the wavenumber expansion, a simple expression for the effective sound speed of perturbations is obtained c_eff^ 2  = ω = (n − 2)/(n + 2) with ω the effective equation of state. We also obtain the first order correction in k^ 2/ω_eff^ 2 , when the wavenumber k of the perturbations is much smaller than the background oscillation frequency, ω_eff. For the standard massive case we have also analysed general anharmonic contributions to the effective sound speed. These results are reached through a perturbed version of the generalized virial theorem and also studying the exact system both in the super-Hubble limit, deriving the natural ansatz for δϕ; and for sub-Hubble modes, exploiting Floquet’s theorem.

Differences and connections: beyond universal theories in planning, urban, and heritage studies

The annual Young Academics network of the Association of European School of Planning (AESOP YA) conference, entitled Differences and Connections, was held for the first time in a Southern Italian city, Palermo, Italy, during 23–26 March 2015. The call for papers attracted a wide range of authors within the field of planning and other related fields. Forty-five contributions by young academic scholars, representing 19 countries, were selected by the conference scientific committee to critically explore the themes of the conference.

New theories in physics : proceedings of the XI Warsaw Symposium on Elementary Particle Physics, 23-27 May, 1988, Kazimierz, Poland /

Mode of access: Internet.

Applications of Quantum Field Theory, From the Formal to the Phenomenological

Thesis (Ph.D.)--University of Washington, 2016-06

Do predators aggregate in response to pest density in agroecosystems? Assessing within-field spatial patterns

1. The spatial heterogeneity of predator populations is an important component of ecological theories pertaining to predator-prey dynamics. Most studies within agricultural fields show spatial correlation (positive or negative) between mean predator numbers and prey abundance across a whole field over time but generally ignore the within-field spatial dimension. We used explicit spatial mapping to determine if generalist predators aggregated within a soybean field, the size of these aggregations and if predator aggregation was associated with pest aggregation, plant damage and predation rate. 2. The study was conducted at Gatton in the Lockyer Valley, 90 km west of Brisbane, Australia. Intensive sampling grids were used to investigate within-field spatial patterns. The first row of each grid was located in a lucerne field (10 m from interface) and the remaining rows were in an adjacent soybean field. At each point on the grid the abundance of foliage-dwelling and ground-dwelling pests and predators was measured, predation rates [using sentinel Helicoverpa armigera (Hubner) egg cards] and plant damage were estimated. Eight grids were sampled across two summer cropping seasons (2000/01, 2001/02). 3. Predators exhibited strong spatial patterning with regions of high and low abundance and activity within what are considered to be uniform soybean fields. Ground-dwelling and foliage-dwelling predators were often aggregated in patches approximately 40 m across. 4. Lycosidae (wolf spiders) displayed aggregation and were consistently more abundant within the lucerne, with a decreasing trap catch with distance from the lucrene/soybean interface. This trend was consistent between subsequent grids in a single field and between fields. 5. The large amount of spatial variability in within-field arthropod abundance (pests and predators) and activity (egg predation and plant damage) indicates that whole field averages were misleading. This result has serious implications for sampling of arthropod abundance and pest management decision-making based on scouting data. 6. There was a great deal of temporal change in the significant spatial patterns observed within a field at each sampling time point during a single season. Predator and pest aggregations observed in these fields were generally not stable for the entire season. 7. Predator aggregation did not correlate consistently with pest aggregation, plant damage or predation rate. Spatial patterns in predator abundance were not associated consistently with any single parameter measured. The most consistent positive association was between foliage-dwelling predators and pests (significant in four of seven grids). Inferring associations between predators and prey based on an intensive one-off sampling grid is difficult, due to the temporal variability in the abundance of each group. 8. Synthesis and applications. This study demonstrated that generalist predator populations are rarely distributed randomly and field edges and adjacent crops can have an influence on within-field predator abundance. This must be considered when estimating arthropod (pest and predator) abundance from a set of samples taken at random locations within a field.

A theoretical and experimental analysis of the no-load air gap magnetic field in squirrel cage induction machines

In induction machines the tooth frequency losses due to permeance variation constitute a signif'icant, portion of the total loss. In order to predict and estimate these losses it, is essential to obtain a clear understanding of the no-load distribution of the air gap magnetic field and the magnitude of flux pulsation in both stator and rotor teeth. The existing theories and methods by which the air gap permeance variation in a doubly slotted structure is calculated are either empirical or restricted. The main objective of this thesis is to obtain a detailed analysis of the no-load air gap magnetic field distribution and the effect of air gap geometry on the magnitude and waveform of the tooth flux pulsation. In this thesis a detaiiled theoretical and experimental analysis of flux distribution not only leads to a better understanding of the distribution of no-load losses but also provides theoretical analysis for calculating the losses with greater accuracy

Electronic Education in the Field of Electrical Engineering Disciplines. Combined Didactic Interactive Program System

At present in the educational process of electrical engineering disciplines electronic learning program, providing control over reproductive educational-cognitive activity (the decision of standard problems) and universal modeling program systems, for instance Electronics Workbench, giving a chance of organizing productive, in particular research activity are basically used. However universal modeling program systems can not provide auto control over educational-cognitive activity because of the absence of the feedback with students. The combined didactic interactive program system, providing the closed directed auto control over both the reproductive and productive heuristic educational-cognitive activity of the student is offered.

A WEB-System for Computer Experiments in the Field of Program Transformations

The paper presents basic notions and scientific achievements in the field of program transformations, describes usage of these achievements both in the professional activity (when developing optimizing and unparallelizing compilers) and in the higher education. It also analyzes main problems in this area. The concept of control of program transformation information is introduced in the form of specialized knowledge bank on computer program transformations to support the scientific research, education and professional activity in the field. The tasks that are solved by the knowledge bank are formulated. The paper is intended for experts in the artificial intelligence, optimizing compilation, postgraduates and senior students of corresponding specialties; it may be also interesting for university lecturers and instructors.

Minimum Mean Square Error Approach in Images Processing for Full-field Displacements and Deformation Measurements

A vision system is applied to full-field displacements and deformation measurements in solid mechanics. A speckle like pattern is preliminary formed on the surface under investigation. To determine displacements field of one speckle image with respect to a reference speckle image, sub-images, referred to Zones Of Interest (ZOI) are considered. The field is obtained by matching a ZOI in the reference image with the respective ZOI in the moved image. Two image processing techniques are used for implementing the matching procedure: – cross correlation function and minimum mean square error (MMSE) of the ZOI intensity distribution. The two algorithms are compared and the influence of the ZOI size on the accuracy of measurements is studied.

Úton egy fenntartható gazdasági paradigma felé – A komplexitás befogadása a hálózati elméleteken keresztül (Towards a sustainable economic paradigm – Acceptance of the complexity through network theories)

Mára elkerülhetetlennek tűnik a gondolati váltás a gazdaságtudományok területén annak érdekében, hogy közelebb kerüljünk a hármas (gazdasági, társadalmi, környezeti) válságot előidéző problémák megoldásaihoz. A szerzők cikkükben amellett érvelnek, hogy a komplexitás befogadása kezdeti törekvésként értelmezhető azon az úton, amely a mindennapokban érzékelhető társadalmi és ökológiai problémák megoldásához vezet. Már léteznek olyan gazdaság- és vállalatelméletek, amelyek kezdik megkérdőjelezni az eddigi főáramú koncepciókat, és készek arra, hogy elveiket, elméleteiket a működési környezet bonyolultságát elfogadva alakítsák ki, és így találjanak mindennapos megoldásokat a gazdasági működésben. Ilyen például – a cikkben szereplő – IMP (Industrial Marketing and Purchasing) csoport hálózatelmélete. A szerzők azt kívánják bemutatni, hogy az ilyen hálózatelméletek alkalmasak arra, hogy a vállalatközi szférán túl is befolyásolják azt, ahogyan a vállalatok döntéseiket meghozzák és kapcsolataikat kezelik. ______ Today, it seems inevitable change of thought in the field of economics in order to get closer to solutions of problems which induced the triple (economic, social, environmental) crisis. In their article, the authors argue that the reception of complexity can be interpreted as an initial effort on the path that leads to the solutions of the everyday perceived social and ecological problems. The authors aim to present that the IMP (Industrial Marketing and Purchasing) group network theory is able to influence beyond the sphere of inter-company, that companies take their decisions and their relationships are treated.

Do the Messages Matter? An Investigation of Classroom Messages and College Students’ Personal Theories about Education

Students hold a number of personal theories about education that influence motivation and achievement in the classroom: theories about their own abilities, knowledge, and the learning process. Therefore, college instructors have a great interest in helping to develop adaptive personal theories in their students. The current studies investigated whether specific messages that instructors send in college classroom might serve as a mechanism of personal theory development. Across 2 studies, 17 college instructors and 401 students completed surveys assessing their personal theories about education at the beginning and end of college courses. Students and instructors reported hearing and sending many messages in the classroom, including instructor help messages, conciliatory messages, uncertainty in the field messages, differential ability messages and generalized positive and negative feedback. Between-class and within-class differences in message reports were associated with students’ personal theories at the end of their courses, controlling for initial personal theories. Students’ initial personal theories were also related to the messages students reported hearing. The findings demonstrate the utility of assessing non-content messages in college classrooms as potential mechanisms for changing students’ personal theories in college. Implications for research and practice are discussed.

Sustainable Business Models – What Do Management Theories Say?

Literature describing the notion and practice of business models has grown considerably over the last few years. Innovative business models appear in every sector of the economy challenging traditional ways of creating and capturing value. However, research describing the theoretical foundations of the field is scarce and many questions still remain. This article examines business models promoting various aspects of sustainable development and tests the explanatory power of two theoretical approaches, namely the resource based view of the firm and transaction cost theory regarding their emergence and successful market performance. Through the examples of industrial ecology and the sharing economy the author shows that a sharp reduction of transaction costs (e.g. in the form of internet based systems) coupled with resources widely available but not utilised before may result in fast growing new markets. This research also provides evidence regarding the notion that these two theoretical approaches can complement each other in explaining corporate behaviour.

A Study of Implicit Leadership Theories Among Business & Management Undergraduate Students

This qualitative study explores the subjective experience of being led by investigating the impact of their Implicit Leadership Theories (ILTs) on followers’ cognitive processes, affective responses and behavioural intentions towards leadership-claimants. The study explores how such responses influence the quality of hierarchical work-place relationships using a framework based on Leader-Member Exchange (LMX) Theory. The research uses focus groups to elicit descriptions of ILTs held by forty final year undergraduate Business and Management students. The data was then analysed using an abductive process permitting an interpretative understanding of the meanings participants attach to their past experiences and future expectations. This research addresses a perceived gap by making a theoretical contribution to knowledge and understanding in this field, focusing on how emotional responses affect their behaviour, how this impacts on organisational outcomes, and what the implications are for HRD practitioners. The findings support previous research into the content and structure of ILTs but extend these by examining the impact of affect on workplace behaviour. Findings demonstrate that where follower ILT needs are met then positive outcomes ensued for participants, their superiors, and their organisations. Conversely, where follower ILT needs are not matched, various negative effects emerged ranging from poor performance and impaired well-being, to withdrawal behaviour and outright rebellion. The research findings suggest dynamic reciprocal links amongst outcomes, behaviours, and LMX, and demonstrate an alignment of cognitive, emotional and behavioural responses that correspond to either high-LMX or low-LMX relationships, with major impacts on job satisfaction, commitment and well-being. Copyright

Black hole scattering from Worldline Quantum Field Theory and the Classical Double Copy of Spinning particles

This PhD thesis focuses on studying the classical scattering of massive/massless particles toward black holes, and investigating double copy relations between classical observables in gauge theories and gravity. This is done in the Post-Minkowskian approximation i.e. a perturbative expansion of observables controlled by the gravitational coupling constant κ = 32πGN, with GN being the Newtonian coupling constant. The investigation is performed by using the Worldline Quantum Field Theory (WQFT), displaying a worldline path integral describing the scattering objects and a QFT path integral in the Born approximation, describing the intermediate bosons exchanged in the scattering event by the massive/massless particles. We introduce the WQFT, by deriving a relation between the Kosower- Maybee-O’Connell (KMOC) limit of amplitudes and worldline path integrals, then, we use that to study the classical Compton amplitude and higher point amplitudes. We also present a nice application of our formulation to the case of Hard Thermal Loops (HTL), by explicitly evaluating hard thermal currents in gauge theory and gravity. Next we move to the investigation of the classical double copy (CDC), which is a powerful tool to generate integrands for classical observables related to the binary inspiralling problem in General Relativity. In order to use a Bern-Carrasco-Johansson (BCJ) like prescription, straight at the classical level, one has to identify a double copy (DC) kernel, encoding the locality structure of the classical amplitude. Such kernel is evaluated by using a theory where scalar particles interacts through bi-adjoint scalars. We show here how to push forward the classical double copy so to account for spinning particles, in the framework of the WQFT. Here the quantization procedure on the worldline allows us to fully reconstruct the quantum theory on the gravitational side. Next we investigate how to describe the scattering of massless particles off black holes in the WQFT.