"This study characterizes the image quality parameters of a clinical full-field digital mammography system at various x-ray spectral conditions. The energy of the incident x-ray beam, the spectral characteristics, and breast thickness impact the physical performance such as the detective quantum efficiency of the system, thereby affecting the overall performance. The modulation transfer function, noise power spectrum were measured without the anti-scatter grid, and the detective quantum efficiency was calculated for different incident x-ray conditions. Detective quantum efficiency was also calculated with the anti-scatter grid placed above the detector to study its impact. Results indicate a substantial drop in the detective quantum efficiency with the anti-scatter grid under certain conditions. It was also determined that detective quantum efficiency decreases as x-ray beam hardening is increased. A spatial frequency-dependent cascaded liner systems model was developed to predict the detective quantum efficiency of the system for different target-filter combinations. This theoretical model is based upon a serial cascade approach in which the system is conceptually divided into a number of discrete stages. Each stage represents a physical process having intrinsic signal and noise transfer properties. A match between the predicted data and the experimental detective quantum efficiency data confirmed the validity of the model. Contrast-detail performance, a widely used quality control tool to assess clinical imaging systems, for the clinical full-field digital mammography was studied using a commercially available CDMAM phantom to learn the effects of Joint Photographic Experts Group 2000 (JPEG2000) compression technique on detectability. A 4-alternative forced choice experiment was conducted. The images were compressed at three different compression ratios (10:1, 20:1 and 30:1). From the contrast-detail curves generated from the observer data at 50% and 75% threshold levels, it was concluded that uncompressed images exhibit lower (better) contrast-detail characteristics than compressed images but a certain limit to compression, without substantial loss of visual quality, can be used."

The aim of the present study was to investigate the link between ruminative processes and dysregulated behaviors. Accordingly, the emotional cascade model (Selby et al., 2008 / 2009) was tested in a sample of Turkish university students using structural equation modeling. The emotional cascade model posits that the link between emotional and behavioral dysregulation may be through emotional cascades, which are repetitive cycles of rumination and negative affect that result in an increased attention paid to the emotional stimuli and intensification of emotional distress. Dysregulated behaviors, such as non-suicidal self-injury, are used in order to break this cycle and distract the person from ruminative processes. In the first part of the study, a common measure of cognitive emotion regulation, namely The Cognitive Emotion Regulation Questionnaire (CERQ / Garnefski et al., 2001) was adapted into Turkish and its psychometric properties were investigated. Results suggested that the Turkish version of the CERQ is a reliable and valid meausure of cognitive coping. Next, a structural equation model was tested to assess the relationship between emotional cascades (as indicated by rumination, thought suppression, catastrophizing) and behavioral dysregulation (as indicated by binge eating, non-suicidal self-injury, excessive reassurance-seeking, and drinking to cope). The results showed that the emotional cascades are associated to behavioral dysregulation. This relationship, however, did not remain significant when the effect of current psychological distress on behavioral dysregulation was controlled for. The importance and possible implications of the present study was discussed.

Online social networks (OSNs) have become a powerful medium of communicating, sharing and disseminating information. Because of popularity and availability of OSNs throughout the world, the connected users can spread information faster and thus propagate influence over each other constantly. Due to such impact, a lot of applications on OSNs focused on picking an initial set of users (seeds) to infuse their message in the OSN. Due to huge size of the network, the main challenge in picking the initial set is to maximize the resultant influence over the users in the network. The optimization problem of finding out the most influential set of members in an OSN for maximization of influence is an NP-hard problem. In this paper, we propose using the Positive Influential Dominating Set (PIDS) algorithm for the initial seed. PIDS is a well-known algorithm which determines the influential backbone nodes in the networks. We implemented PIDS-based influence maximization by using different propagation models. We compared PIDS performance to that of the existing approaches based on greedy and random heuristics. The experimental results from extensive simulation on real-world network data sets show that PIDS gives better influence spread than greedy and random for both Independent Cascade Model and Linear Threshold Model of influence propagation. PIDS is also scalable to large networks and in all size ranges, it performs well in influence maximization.

Non-suicidal self-injury (NSSI), the deliberate and direct damage of one’s body tissue without suicidal intent, is a pervasive public health concern often leading to clinically significant long-term consequences (e.g., permanent scarring, hospitalization) that is theorized to be facilitated by negative affect and emotion dysregulation. The Emotional Cascade Model proposes that NSSI partially functions to disrupt the reciprocal and rapid amplification of negative affect driven by rumination. However, limited research has focused on state rumination and the distinct contribution of maladaptive and adaptive rumination subtypes, as well as the role of positive affect within this framework. Thus, the purpose of the current study was to replicate and explore the independent influences of overall and momentary (1) positive and negative affect and (2) rumination on NSSI acts and urges, as well as (3) the extent to which rumination moderates the relationship between affect and NSSI. To do so, rumination, affect, and NSSI urges and acts were assessed 4 times daily via ecological momentary assessment for 21-days among thirty undergraduate participants with past month NSSI. Our results partially replicated existing literature, such that overall negative affect was associated with greater overall NSSI urge strength and momentary negative affect and rumination predicted stronger NSSI urges at the next alert, with increased momentary rumination strengthening the relationship between momentary negative affect and NSSI urge. Exploratory investigations of overall and momentary positive affect showed some negative associations with NSSI urges and behaviors, with no moderating effect of rumination. Data did not support the independent examination of maladaptive and adaptive rumination subtypes. Taken together, this study highlighted the importance of exploring state rumination (in addition to trait) and affect in understanding NSSI thoughts and behaviors, and calls for future studies to further investigate distinct properties of rumination to understand its impact on specific emotions that maintain NSSI engagement. / Psychology

Borderline personality disorder (BPD) is an impairing mental illness and has a core component of emotional dysregulation. Evidence suggests the emotional cascade model describes how this emotional dysregulation leads to engaging in risky and life-threatening behaviors, such as non-suicidal self-injury (NSSI). Specifically, this model describes rumination as a cognitive component that links the emotional and behavioral dysregulation. The current study aimed to expand the model by investigating how individuals with heightened BPD traits engage in NSSI and in cognitive strategies to cope with their negative affect. Specifically, it was investigated whether behaviors like suicide attempts and cognitions differentiated between those with mild/moderate and severe NSSI. Criterion for severe NSSI was hospitalization or medical care because of NSSI. Participants (N = 292) were screened to endorse a history of NSSI and then self-selected to take a self-report survey through Mturk. Correlations and a binomial logistic regression were completed. Results indicated suicide attempts, BPD symptoms, and anger rumination differentiated mild/moderate and severe NSSI. Evidence reinforces the strong relationships between NSSI, suicide attempts, and BPD. Additionally, it reinforces anger rumination as a potential cognitive mechanism in NSSI. Future research can continue to test this model and include other potential thought processes to increase efficiency in assessment and treatment of BPD and NSSI.

No description available.

Auditorische Transduktion beschreibt die Umwandlung von Schall in elektrische Signale in Rezeptorzellen. Dies geschieht durch eine Kette biophysikalischer Prozesse: mechanische Ankopplung der Schallwelle, Öffnung von mechanosensitiven Ionenkanälen in den Rezeptorzellen, Ansammlung des Membranpotentials und Auslösung von Aktionspotentialen. In dieser Arbeit wird die damit verbundene Signalverarbeitung am Beispiel der Rezeptorzellen im Ohr von Heuschrecken untersucht. Die Transduktion wird dazu als Kaskade einzelner funktioneller Module beschrieben. Es wird gezeigt, wie derartige Module aus der Beobachtung der System-Antwort, hier der Aktionspotentiale im auditorischen Nerv, mit Hilfe der Iso-Antwort-Methode charakterisiert werden können. Dabei werden im Experiment unterschiedliche akustische Reize ermittelt, die die gleiche System-Antwort liefern. In drei aufeinander aufbauenden experimentellen Untersuchungen führt dies zu folgenden Ergebnissen: 1) Für stationäre Signale wird die Feuerrate der Rezeptorzellen durch die Energie der Trommelfell-Schwingung reguliert. 2) Die auditorische Transduktion lässt sich durch eine Kaskade aus zwei linearen Filtern und zwei nicht-linearen Transformationen (LNLN-Kaskade) beschreiben. Die involvierten Prozesse agieren im sub-Millisekunden-Bereich und können mit der beschriebenen Methode - trotz der auf etwa eine Millisekunde beschränkten Präzision der Aktionspotentiale - mit einer Genauigkeit von ca. 10 Mikrosekunden vermessen werden. 3) Die Adaptation der Feuerrate enthält neben einem dominierenden rückgekoppelten Prozess, der durch die Feuerrate selbst gesteuert wird, auch eine Komponente, die direkt durch das Eingangssignal, die Schallintensität, ausgelöst wird und mechanischer Natur ist. Die Ergebnisse spiegeln die hohen Anforderungen an das zeitliche Auflösungsvermögen im Ohr wider. Die verwendete Methodik ist jedoch auch auf viele andere systemtheoretische Untersuchungen biophysikalischen Kaskaden anwendbar. / Auditory transduction describes the conversion of sound into electrical signals in receptor cells. A sequence of biophysical processes is involved: the mechanical coupling of the sound-pressure wave, the opening of mechanosensory ion channels in the receptor cells, the accumulation of membrane potential and the generation of action potentials. In this work, the signal processing in receptor cells is investigated. The ears of grasshoppers serve as a model system, and transduction is described as a cascade of functional modules. It is shown how such modules can be characterized by the iso-response method from observations of the system''s response. To this end, different acoustic stimuli are determined experimentally that trigger the same response. In three consecutive experimental investigations, this approach leads to the following results: 1) For stationary signals, the firing rate of the receptor neurons is governed by the energy of the ear-drum vibrations. 2) Auditory transduction can be described by a cascade that consists of two linear filters and two nonlinear transformations (LNLN cascade). The processes involved act on sub-millisecond time scales and can be analyzed by the described method with a resolution of around 10 microseconds - despite the limited precision of the action potentials near one millisecond. 3) Spike-frequency adaptation is governed by a feedback process, which is governed by the firing rate, but also contains a feedforward component triggered by the system''s input, the sound intensity. This component is of mechanical origin. The results reflect the high demands for temporal resolution in the ear. The applied method, however, can also be used for a large range of further system-theoretical investigations of biophyical cascades.

South Africa has witnessed radical policy reforms since the advent of the new democratic dispensation in 1994. As provincial, district and local practitioners developed responses to those new national education policies, implementation issues were revealed in all their complexity. Policy implementation became one of the most difficult challenges South Africa had to contend with. It necessitated the development of the capacity of the state and its people to implement policy. The complexities of the people development environment in South Africa create a range of challenges for development. The lack of multi-level empirical data on training effects continues to exacerbate this state of affairs. This context requires that comprehensive assessment mechanisms be put in place for training programmes aimed at the realisation of policy goals. The broad purpose of this inquiry, therefore, is to determine the impact of an education management development training intervention as it passes through different levels of the education system in South Africa - national, provincial, district and local. The following key questions guided this investigation. Firstly, how do stakeholder understandings of “education management development” transfer from one level to another in a cascade model of training? And secondly, what is the operational impact of an education management development-training programme at the different levels (i.e., province, district and school) of the education system? Questionnaires, free attitude interviews and observations were used as key data collection instruments. Data was analysed using a combination of quantitative and qualitative strategies for making sense of the training information. Data was interpreted against the backdrop of the literature on the “transfer of training”, and these findings are represented in the last three chapters of this thesis. This research generated four major findings, with a variety of subsidiary findings, which deepen our insights into policy implementation as it relates to education management development in South Africa. Some of the major findings of this study are that: a) The organisers did not in the first place conduct the baseline study on training needs and secondly, they did not take into consideration the organisational requirements of the anticipated training. This anomaly could ultimately compromise the outcomes of this intervention. b) The policy deployment processes of the North West Department of Education (of ensuring that the governmental policies for quality, cost and service delivery are understood from the highest to the lowest level of the organisation) are fraught with problems that undermined basic understandings of the Education Management Development training programme which was conducted between 1998 – 2000. c) Successful policy implementation depends crucially on resource allocation and, in the case of the Education Management Development Training Programme, the nature and magnitude of allocated resources e.g., transport provision could not guarantee positive training results; and d) The overly rationalistic view adopted by the trainers of the Education Management development-training programme did not take into account the complex contexts within which change unfolds. Resultantly, the changing of the roles of facilitators could not be planned-for in advance. The significance of this study is that it identifies the barriers to learning in training events, and sheds new light on the transfer of training problem that continues to undermine organisational change and human resource development. Some of the unique findings of the study can be found in the fact that the Expert Trainers could only recall a few intentions of the EMD modular training. The District Facilitators displayed limited knowledge of the disciplinary procedures in their areas of operation and there was limited conceptualisation of the EMD by the principals of schools. / Thesis (PhD (Education Policy Studies))--University of Pretoria, 2005. / Education Management and Policy Studies / unrestricted

No description available.

Outcomes Based Education (OBE), has been, since its inception, fraught with problems. OBE in its very nature is complex. To fully embrace this method and ensure its success, schools must be able to make the necessary paradigm shift. This can only be achieved when schools receive relevant and empowering training, support and development. In other words, organisational development must be the key words. The aim of this study is to explore the impact of organisational development interventions on the implementation of OBE. The case study method was employed where it was realised that schools that received organisational development interventions, together with Outcomes Based Education, were able to implement this method with greater understanding, skill, and confidence. The investigation recommends an organisational development design that could be used instead of the cascade model, and provides suggestions on what can be done to ensure a more successful implementation process. / Educational Studies / M. Ed (Education Management)