• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 116
  • 52
  • 25
  • 23
  • 13
  • 6
  • 4
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 292
  • 69
  • 56
  • 36
  • 33
  • 32
  • 32
  • 28
  • 27
  • 24
  • 21
  • 20
  • 19
  • 19
  • 18
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Resonant and high resolution photoemission of rare-earth cobalt oxides

Rafique, Hafiz Muhammad January 2010 (has links)
LnBaCo2O5+δ (Ln-112) where Ln = lanthanide element; 0 ≤ δ ≤1 and LnBaCo4O7+δ (Ln-114) are highly correlated cobalt oxides. Synchrotron photoemission spectroscopy of LnBaCo2O5+δ (Ln = Gd, Dy, Dy1-xTbx) and LnBaCo4O7 (Ln = Yb) has been undertaken at the UK Synchrotron Radiation Source (Daresbury Laboratory).During the photoemission experiments, the samples were observed to be contaminated due to residual gases inside the main vacuum chamber. The surface degradation of the samples is studied using the difference spectra generated from the valence band spectra of freshly scraped and contaminated samples and the nature of contaminated species on these samples is identified in the light of the reviewed literature. High-resolution photoemission is carried out to study the metal-insulator (MI) transition in double perovskites LnBaCo2O5+δ (Ln = Gd, Dy, Dy1-xTbx - Ln-112; 0 ≤ δ ≤ 1) as a function of temperature. The high-resolution photoemission results of single crystal samples of GdBaCo2O5.5, DyBaCo2O5.5 and Dy1-xTbxBaCo2O5+δ show that the temperature-based MI transitions in these compounds occur in the 300-400 K temperature range. A post-growth oxygen annealing treatment for as-grown single crystals of Ln-112 is necessary, achieving oxygen contents close to 5.50, to observe a marked nonmetal-to-metal transition. Resonant photoemission is used to identify the atomic parentage of the valence band states. A comparison of the electronic structure of LnBaCo2O5+δ (Ln = Gd, Dy, Dy1-xTbx - Ln-112; 0 ≤ δ ≤ 1) and LnBaCo4O7 (Ln = Yb - Ln-114) single-crystal surfaces is made using synchrotron photoemission spectroscopy. In both cases, the states close to the Fermi energy are found to be of mixed Co 3d/O 2p character, and the comparison allows identification of states due to low spin Co³⁺ in octahedral environments. The contributions from Ln elements to the valence band are found at higher binding energies.
152

Assessment of fun from the analysis of facial images / Avaliação de diversão a partir da análise de imagens faciais

Luiz Carlos Vieira 16 May 2017 (has links)
This work investigates the feasibility of assessing fun from only the computational analysis of facial images captured from low-cost webcams. The study and development was based on a set of videos recorded from the faces of voluntary participants as they played three different popular independent games (horror, action/platform and puzzle). The participants also self-reported on their levels of frustration, immersion and fun in a discrete range [0,4], and answered the reputed Game Experience Questionnaire (GEQ). The faces were found on the videos collected by a face tracking system, developed with existing implementations of the Viola-Jones algorithm for face detection and a variation of the Active Appearance Model (AAM) algorithm for tracking the facial landmarks. Fun was represented in terms of the prototypic emotions and the levels of frustration and immersion. The prototypic emotions were detected with a Support Vector Machine (SVM) trained from existing datasets, and the frustration, immersion and fun levels were detected with a Structured Perceptron trained from the collected data and the self reported levels of each affect, as well as estimations of the gradient of the distance between the face and the camera and the blink rate measured in blinks per minute. The evaluation was supported by a comparison of the self-reported levels of each affect and the answers to GEQ, and performed with measurements of precision and recall obtained in cross-validation tests. The frustration classifier could not obtain a precision above chance, mainly because the collected data didn\'t have enough variability in the reported levels of this affect. The immersion classifier obtained better precision particularly when trained with the estimated blink rate, with a median value of 0.42 and an Interquartile Range (IQR) varying from 0.12 to 0.73. The fun classifier, trained with the detected prototypic emotions and the reported levels of frustration and immersion, obtained the best precision scores, with a median of 0.58 and IQR varying from 0.28 to 0.84. All classifiers suffered from low recall, what was caused by difficulties in the tracking of landmarks and the fact that the emotion classifier was unbalanced due to existing datasets having more samples of neutral and happiness expressions. Nonetheless, a strong indication of the feasibility of assessing fun from recorded videos is in the pattern of variation of the levels predicted. Apart from the frustration classifier, the immersion and the fun classifier were able to predict the increases and decreases of the respective affect levels with an average error margin close to 1. / Este trabalho investiga a viabilidade de medir a diversão apenas a partir da análise computacional de imagens faciais capturadas de webcams de baixo custo. O estudo e desenvolvimento se baseou em vídeos gravados com as faces de voluntários enquanto jogavam três diferentes jogos populares e independentes (horror, ação/plataforma e puzzle). Os participantes também reportaram seus níveis de frustração, imersão e diversão no intervalo discreto [0, 4], e responderam ao renomado Game Experience Questionnaire (GEQ). Faces foram encontradas nos vídeos coletados utilizando um sistema desenvolvido com implementações existentes do algoritmo de Viola-Jones para a detecção da face e uma variação do algoritmo Active Appearance Model (AAM) para o rastreamento das marcas faciais. A diversão foi representada em termos das emoções prototípicas e dos níveis de frustração e imersão. As emoções prototípicas foram detectadas com uma Máquina de Vetores de Suporte (SVM) treinada com bases de dados existentes, e os níveis de frustração, imersão e diversão foram detectados com um Perceptron Estruturado treinado com os dados coletados e os níveis reportados de cada afeto, com o gradiente da distância entre a face e a câmera, e com a taxa de piscadas por minuto. A avaliação foi apoiada pela comparação dos níveis reportados com as respostas ao GEQ, e executada com métricas de precisão e revocação (recall) obtidas em testes de validação cruzada. O classificador de frustração não obteve uma precisão acima de chance, principalmente porque os dados coletados não tiveram variabilidade suficiente nos níveis reportados desse afeto. O classificador de imersão obteve uma precisão melhor particularmente quando treinado com a taxa de piscadas, com uma média de 0.42 e uma Amplitude Interquartil (IQR) entre 0.12 e 0.73. O classificador de diversão, treinado com as emoções prototípicas e os níveis reportados de frustração e imersão, obteve a melhor precisão, com média de 0.58 e IQR entre 0.28 e 0.84. Todos os classificadores sofreram de baixa revocação, causada por dificuldades no rastreamento das marcas faciais e pelo desbalanceamento do classificador de emoções, cujos dados de treinamento continham mais exemplos de expressões neutras e de felicidade. Ainda assim, um forte indicador da viabilidade de medir diversão a partir de vídeos está nos padrões de variação dos níveis previstos. Com exceção da frustração, os classificadores de imersão e de diversão foram capazes de prever os aumentos e reduções dos níveis dos respectivos afetos com uma margem de erro média próxima de 1.
153

A qualitative examination of tilt in League of Legends esports players / En kvalitativ undersökning av tilt i League of Legends esportspelare

Fuentes, Raul January 2021 (has links)
Some video games offer, today, high-level competitive performance in the form of esports – a discipline recognized as a performance domain in need of investigation within a sport psychological perspective. Tilt, described as severe frustration resulting in suboptimal performance, is a common, yet still under-investigated performance debilitating phenomenon in esports. The aim of the present study was to gain an understanding of factors and processes relating to tilt in the esports of League of Legends. To that end, a qualitative method was applied using thematic analysis to explore (1) antecedents of tilt, (2) the effects of tilt on performance, and (3) players’ strategies to manage tilt-inducing situations. Findings show players experience antecedents of tilt to be teammates failing to meet the expectations of the players, teammates’ toxic behaviour, players failing to meet their own expectations, and negative emotions. These events can result in the players experiencing a sense of discouragement, a loss of control, misplaced attention, as well as displaying toxic behaviour. Lastly, the players resort to managing tilt-inducing situations by muting the in-game chat, redirecting attention towards controllable actions, and acceptance of mistakes and situations in general. These findings suggest tilt processes to be partly influenced by the players’ teammates’ actions, thus different social contexts may influence the experience of tilt. Further, findings indicate the players’ experience of discouragement when under tilt as an additional factor related to tilt, which is discussed as potentially unique to the context of players in LoL.
154

A comparison of authoritarian and ressentient attitudes among high school coaches, college physical education majors, and other college students

Brautigan, Roger L. 01 January 1974 (has links)
The questions posed by this study were: (1) To determine the relationship between authoritarianism and ressentience among high school coaches employed within San Joaquin County, California.; and (2) To compare authoritarianism and ressentience among high school coaches within San Joaquin County, California, a sample of college students majoring in physical education, and a sample of college students majoring in a subject area other than physical education attending the University of the Pacific, Stockton, California.
155

Low-Energy Spin Dynamics in geometrically frustrated 3d-Magnets and Single-Ion Spin Systems: µ+SR studies on BaTi0:5Mn0:5O3 and NaCaCo2F7 and 57Fe-Mössbauer spectroscopy on Fe-diluted Li2(Li1-xFex)N

Bräuninger, Sascha Albert 28 February 2020 (has links)
In this work, I present nuclear probe spectroscopy studies, in detail, µ+SR and 57Fe-Mössbauer spectroscopy on solid-state systems with localized magnetic moments of 3d transition-metal ions supported by density functional theory calculations. Local probes are able to extract local quantities, e.g. the spin dynamics of the 57Fe site or the local, mostly interstitial µ+ site to distinguish between di_erent magnetic phases. The density functional theory calculations help to identify the muon site position from which the local quantity depends. My µ+SR studies on frustrated 3d magnets with quenched disorder concern the physics of phase transitions, avoided order-by-disorder, quantum uctuations or the appearance of spin-liquid-by-disorder. µ+SR is able to identify quantum spinliquid-like ground states without symmetry breaking or static magnetic order by the magnetic field at the muon site. BaTi0.5Mn0.5O3 is a magnetically highly-frustrated double perovskite with quenched disorder.It shows no freezing temperature or no frequency dependence of x1as expected for a spin glass. Microscopically, it is proposed that local interactions between magnetic orphan spins, dimers, and magnetic trimers of Mn4+ play an important role. The µ+SR experiment on BaTi0.5Mn0.5O3 shows an increase of the dynamical muon spin relaxation rate below 3 K which saturates down to 0.019 K coexisting with residual short-range magnetic order (<20% of the signal). A clear difference is observed in comparison with the classical cluster-spin glass SrTi0.5Mn0.5O3 which shows a peak of the zero-field muon spin relaxation rate: a persistent low-energy spin dynamics is present in BaTi0.5Mn0.5O3 down to 20 K. My DFT calculations propose a positive muon site insight the Ba plane close to O atoms. Here, a slight preference of the muon site close to Mn4+ is possible which could put the muon close the orphan spins, dimers, and magnetic trimers, respectively, avoiding the nonmagnetic Ti4+ face-sharing octahedra. Theoretically, a specific ground state of BaTi0.5Mn0.5O3 is not proposed. A clear discrimination between a quantum spin liquid ground state and a mimicry state with the appearance of spin-liquid-by-disorder is not possible from the existing data. I present a µ+SR study on the bond-disordered magnetically highly frustrated pyrochlore fluoride NaCaCo2F7. Neutron spectroscopy studies on NaCaCo2F7 revealed static short-range order consistent with a continuous manifold of cluster-like states being a superposition of noncoplanar ψ2(m3z2-r2) and coplanar ψ3(mx2-y2) states with a correlation length of around 16Å. No evidence for static magnetic long-range order is found in NaCaCo2F7 probed by µ+SR confirming the absence of an order-by-disorder mechanism. The experimental results are not consistent with a classical local-planar XY cluster-spin glassiness. In these µSR experiments, two muon sites are observed. The relative occupancy of both muon sites is nearly temperature independent. Muon site I is a collinear diamagnetic F-µ+-F bound state pulling two F- close towards the muon revealed by the muon spin time evolution. To investigate the pure F-µ+-F bound state in a broad temperature range I have performed an additional µ+SR study on CaF2. This study solved open questions of muon diffusion around 290 K which was observed in NaCaCo2F7 as well. The F-µ+-F spin relaxation indicates the slowing down of the magnetic Co2+ spin fluctuations upon cooling towards the NMR spin freezing temperature Tf≈ 2.4 K. The relaxation rate saturates below 800 mK and remains constant down to 20 mK. The dominant part of the magnetic short-range relaxation signal is a dynamical relaxation as probed by longitudinal magnetic-field experiments. Muon site II exhibits a strong dynamical relaxation rate at 290 K and below and shows persistent µ+ spin dynamics down to 20 mK. Qualitatively, muon site II shows persistent µ+ spin dynamics with one order of magnitude higher dynamical relaxation rates compared to muon site I. DFT calculations of a comparison of the unperturbed unit cells of NaCaCo2F7 and NaCaNi2F7, which has shown just one muon site experimentally, are consistent with a decrease of the energy differences of energy minima and support the experimentally observed muon site ambivalence. In summary, the µ+SR studies propose NaCaCo2F7 as a quantum cluster-spin glass candidate. I present a systematic 57Fe-Mössbauer study on highly diluted Fe centers in Li2(Li1-xFex)N as a function of temperature and magnetic field applied transverse and longitudinal with respect to the single-ion anisotropy axis. Here, Fe is embedded in an α-Li3N matrix. The oxidation state of Fe and possible ferromagnetic nature are in controversial discussions in the literature. Below 30 K the Fe centers exhibit a giant magnetic hyperfine field of BA=70.25(2) T parallel to the axis of strongest electric field gradient Vzz=-154.0(1) V / Å 2. This observation is consistent with a Fe1+d7 charge state with unquenched orbital moment and J=7/2. Fluctuations of the magnetic hyperfine field are observed between 50 K and 300 K and described by the Blume two-level relaxation model consistent with single-atomic magnetism as proven by the invariance of Blume relaxation parameters for the concentration tuning x< 0.025 excluding a ferromagnetic nature. From the temperature dependence of the fluctuation rate an Orbach spin-lattice relaxation process is deduced. An Arrhenius analysis yields a single thermal-activation barrier of EA=570(6) K and an attempt frequency v0=309(10) GHz. Mössbauer spectroscopy studies with applied transverse magnetic fields up to 5 T reveal a large increase of the fluctuation rate by two orders of magnitude. In longitudinal magnetic fields a splitting of the fluctuation rate into two branches is observed. The experimental observations are qualitatively reproduced by a single-ion spin Hamiltonian analysis. It demonstrates that for dominant magnetic quantum tunneling relaxation processes a weak axial single-ion anisotropy D of the order of a few Kelvin can cause a two orders of magnitude larger energy barrier for longitudinal spin fluctuations.
156

Spelkontroller – traditionellt kontra naturligt : En jämförelse mellan traditionella spelkontroller och Ape Escape Controls / Video game controls – traditional versus natural : A comparison between traditional video game controls and Ape Escape Controls

Palmér, Anton, Liljenström, Christopher Robin January 2020 (has links)
En vetenskaplig studie utfördes med fokus på spelkontrollers påverkan på spelarens engagemang och frustration, aspekter som är viktiga för spelares intresse för ett spel. Studien jämför traditionella spelkontroller, som exempel på vanligt förekommande moderna spelkontroller, och Ape Escape-liknande spelkontroller, som anpassar naturligt mappade spelkontroller på ett traditionellt, modernt kontrolldon. Två spelprototyper skapades med en utav de nämnda kontrolltyperna vardera. En studie utfördes med fyra deltagare delade i två deltagargrupper där varje deltagare spelade de två spelprototyperna följt av semi-strukturerade intervjuer med mål att få information kring deras spelupplevelser. Datan analyserades enligt grundad teori vilket uppgav en rad olika mönster angående deltagarnas engagemang och frustration samt hur dessa påverkades av spelkontrollerna hos vardera prototyp. På grund av den låga mängden deltagare är dessa mönster relativt opålitliga vilket bjuder in till framtida studier med fler deltagare och samma fokus på spelkontrollers påverkan på engagemang och frustration.
157

The Direction of Aggression and Group Conformity of Policemen, Narcotic-Addicts, and Seventh Day Adventists as Measured by the Rosenzweig Picture-Frustration Study

Gerlach, Herman 01 1900 (has links)
The present study was an attempt to measure the direction of aggression among three diverse groups, namely, policemen, narcotic-addicts and Seventh Day Adventists. The second aspect of this investigation was to determine the group conformity tendencies of the three basic groups. The Rosenzweig Picture-Frustration Study was used as the measuring instrument.
158

Noncollinear Magnetism in Surfaces and Interfaces of Transition Metals

Tan, Huahai 18 November 2009 (has links)
Noncollinear (NC) magnetism is common in nature, especially when there exist geometrical frustration and chemical imparity in the system. In this work we studied the NC magnetism and the response to external magnetic fields in surfaces and interfaces of transition metals by using an semi-empirical tight-binding (TB) method that parameterized to the ab initio TB-LMTO calculations. We implemented this method to study two systems. The first one is the system of 6 Mn monolayers on Fe(001) substrate. Due to the complex structure and magnetic properties of Mn, we found 23 collinear magnetic configurations but only one NC configuration. The collinear ground state has a layered antiferromagnetic (AFM) coupling which agrees with previous experiments and calculations. In the NC configuration the local AFM coupling in the Mn layers is preserved, but the surface is 90 degree coupled to the substrate. Similar to the experiment in CdCr2O4, we obtained a collinear plateau in the NC evolution of the average magnetic moment in Mn slab under external magnetic fields. Another is the system of a Cr monolayer on a stepped Fe(001) substrate. As expected, the local AFM coupling in the interface of Cr and Fe are preserved. However, the edge Cr atoms is about 90 degree coupled to their nearest Fe neighbors. We also simulated the procedure of adding more Cr coverages gradually to a Cr bilayer coverage. As coverages increase, the magnetic moments in the Cr interface reduce, and the collinear plateau becomes wider as coverages increase. However, the saturation fields in both the two systems are extremely high, around 10 kT.We expect that when the effect of temperature is taken into account, and in some proper systems, the saturation fields could be largely reduced to the scale that can be implemented in experiment, and our study may shed light on information storage devices with ultrahigh storage density.
159

Teachers' Experiences Concerning the Rise in Student Aggression

Works, Doris Massey 01 January 2015 (has links)
This research study addressed the problem of aggressive and disruptive behaviors for kindergarten through Grade 12 students in a school district located in Southeastern United States. The study examined classroom teachers' daily lived experiences with student aggression. Using a phenomenological design and guided by the frustration aggression theory and the social learning theory, the research questions explored teachers' responses to what can be done to help with disruptive and aggressive students and how social learning could help students with these behaviors. Data were collected from interviews with 5 individual teachers who had experienced aggressive and disruptive behaviors; data were also gathered from a focus group of 6 to increase credibility of the final interpretations. Both interview and focus group data were color-coded and thematically analyzed. Emergent themes revealed that aggressive disruptive behaviors included extreme disrespect toward teachers with physical and verbal abuse, and low teacher efficacy. The results indicated that social learning, through positive modeling, was needed to help aggressive disruptive students change their behavior. Teacher recommendations included professional training on social learning strategies, reducing class size, instilling a zero tolerance policy, increasing administrative support, and providing social learning programs for aggressive students. These recommendations could lead to social change by implementing constructive measures to reduce aggression and nurture positive teacher-student relationships by which students are empowered to learn and grow.
160

The Role of Frustration in Intensive Treatment of Childhood Apraxia of Speech

Cook, Shina Jinn January 2021 (has links)
Purpose: This study primarily investigates the effects and influence of frustration in children with childhood apraxia of speech (CAS) in the setting of intensive treatment. Additionally, the study examines the interrater reliability of the frustration rating scale used in an intensive CAS treatment study. Methods: Frustration and treatment data obtained from 17 participants (between 4;0-9;11 years) with CAS in an intensive treatment research study were retrospectively used to determine potential relationships related to frustration in treatment (target complexity, temporal conditions, session number, CAS severity). Interrater reliability of the frustration rating scale was assessed with 34 randomly selected treatment session videos scored by a blinded second rater and compared to original scores. Results: Interrater reliability of the scale was poor to fair but had relatively close agreement within one scale point. Frustration levels were observed to decrease over the course of the treatment period but were typically greater in the afternoon sessions compared to morning. Participants in the complex target treatment condition with lower frustration also exhibited better outcomes than those with greater frustration. No other relationships were observed. Conclusions: Due to relatively poor interrater reliability of frustration scoring system used to obtain data used in the current study, results of the study should be interpreted cautiously. There may be a relationship between frustration levels in children with CAS and treatment conditions and outcomes, but other factors may influence both variables and further investigation into frustration is necessary to draw stronger conclusions. / Public Health

Page generated in 0.1053 seconds