Attacks on Steganographic Systems and Watermarking

Tato práce se zabývá steganalýzou, neboli detekcí steganografie, a dále pak útoky na di- gitální vodoznaky, jejichž úlohou je zneplatnění vodoznaků. V práci je navržena a imple- mentována aplikace, sloužící na detekci stegogramů. Aplikace se zabývá hlavně obrázky, vytvářenými metodou substituce nejméně významných bitů programem QuickStego. Spo- lehlivou detekci zajišťuje navržená metóda, která dekóduje informace vložené do obrázku, a vyhledává specifická data vkládaná programem QuickStego. V závěru práce jsou prováděny experimenty na vzorce obrázků, které potvrzují možnost detekovat stegogramy.This thesis focuses on steganalysis, which is detection of steganography, and then on at- tacks on digital watermarking, which aim to invalidate watermarks. The application for stegograms detection is designed and implemented in this thesis. The application focuses on the images, produced by substitution of the least significant bits in QuickStego program. Reliable detection is insured by the designed method, which decodes information embedded in the image, and searches for specific data embedded by the program QuickStego. In the end of the thesis, few experiments are conducted on the sample images, which confirm the ability of detecting stegograms.

Principal sensemaking and special education discipline : a multiple case study of secondary building-level administrators

This multiple case study -- utilizing an application of educational sensemaking theory -- aimed to examine how building-level administrators made sense of disciplining students with disabilities. This study collected data from seven building-level administrators over four secondary schools within one school district. A three-part, in-depth interview protocol was undertaken with each administrator in addition to document collection and analysis. The findings suggested that the building-level administrators were constrained more heavily by certain aspects of sensemaking. Specifically, they (1) did not have the background knowledge/training in special education to draw from, (2) had previous experiences that reminded them of worst-case occurrences, (3) were given high amounts of autonomy in decision making with very few opportunities to increase knowledge outside of own initiative, and (4) relied on relationships with teachers to help shape their actions. These findings uncovered gaps in how administrators ultimately perceived their roles as leaders of special education and how that impacted their sensemaking when disciplining a student with disabilities. Finally, these findings suggest that districts create practices that identify and fill administrator knowledge gaps, that principal leadership preparation programs concentrate on more special education content, and that awareness be raised that building-level leaders are leaders of special education.Includes bibliographical reference

Higher brain functions served by the lowly rodent primary visual cortex

It has been more than 50 years since the first description of ocular dominance plasticity-the profound modification of primary visual cortex (V1) following temporary monocular deprivation. This discovery immediately attracted the intense interest of neurobiologists focused on the general question of how experience and deprivation modify the brain as a potential substrate for learning and memory. The pace of discovery has quickened considerably in recent years as mice have become the preferred species to study visual cortical plasticity, and new studies have overturned the dogma that primary sensory cortex is immutable after a developmental critical period. Recent work has shown that, in addition to ocular dominance plasticity, adult visual cortex exhibits several forms of response modification previously considered the exclusive province of higher cortical areas. These "higher brain functions" include neural reports of stimulus familiarity, reward-timing prediction, and spatiotemporal sequence learning. Primary visual cortex can no longer be viewed as a simple visual feature detector with static properties determined during early development. Rodent V1 is a rich and dynamic cortical area in which functions normally associated only with "higher" brain regions can be studied at the mechanistic level.National Eye Institute (Grant RO1 EY023037)National Institute of Mental Health (U.S.) (Grant K99 MH09965

Reestruturação de um distrito escolar no nível do condado: uma análise crítica do desenvolvimento de políticas e políticas para a descentralização

Policymakers and educational leaders continue to use school district decentralization as a reform effort that attempts to shift power and authority from central office administration to school-level leadership. In 2015, the Nevada Legislature passed legislation to restructure the Clark County School District (CCSD), the state’s largest school district, with the intent of breaking it up into smaller districts but instead evolving to decentralization. In this article, we use case study methods to explore the events leading up to the reorganization of CCSD. We take a critical perspective on Kingdon’s multiple streams framework to analyze the reorganization efforts, focusing specifically on how Nevada’s political context provided a window of opportunity for the reorganization to occur. We also examine the extent to which equitable educational opportunity was a factor in these efforts. Our analysis of the reorganization of CCSD contributes to a wider understanding of state-level policy development and politics within contemporary educational contexts. In this case, we find that state-level policymakers successfully leveraged the opportunity to enact the power and authority necessary to significantly and rapidly impact the structure of one of the largest school districts in the United States.  Los formuladores de póliticas y los líderes educativos continúan con el uso de la descentralización del distrito escolar como un esfuerzo de reforma que intenta cambiar el poder y la autoridad de la administración de la oficina central al liderazgo a nivel escolar. Durante 2015, la Legislatura de Nevada aprobó una ley para reestructurar el Distrito Escolar del Condado de Clark (CCSD), el distrito escolar más grande del estado, con la intención de dividirlo en distritos más pequeños, pero se desarrolló hacia la descentralización. En este artículo, usamos métodos de estudio de caso para explorar los eventos que causaron la reorganización de CCSD. Tomamos una perspectiva crítica sobre el multiple streams framework de Kingdon para analizar los esfuerzos de reorganización, centrándonos específicamente en como el contexto político de Nevada creo oportunidades para que se produzca la reorganización. También examinamos el punto en cual la oportunidad educativa equitativa fue un factor en estos esfuerzos. Nuestro análisis de la reorganización de CCSD contribuye a una comprensión más amplia del desarrollo de la política y las pólizas a nivel estatal dentro de contextos educativos contemporáneos. En este caso, encontramos que los legisladores a nivel estatal exitosamente aprovecharon la oportunidad de representar el poder y la autoridad necesaria para tener un impacto significativo y rápido en la estructura de uno de los distritos escolares más grandes de los Estados Unidos.Os formuladores de políticas e os líderes educacionais continuam a usar a descentralização do distrito escolar como um esforço de reforma que tenta mudar o poder e a autoridade da administração do escritório central para a liderança do nível escolar. Em 2015, o Legislativo de Nevada aprovou uma lei para reestruturar o Distrito Escolar do Condado de Clark (CCSD), o maior distrito escolar do estado, com a intenção de dividi-lo em distritos menores, mas desenvolvido para a descentralização. Neste artigo, utilizamos métodos de estudo de caso para explorar os eventos que causaram a reorganização do CCSD. Nós tomamos uma perspectiva crítica sobre o quadro de múltiplos fluxos de Kingdon para analisar os esforços de reorganização, enfocando especificamente sobre como o contexto político em Nevada cria oportunidades de reorganização. Nós também examinamos o ponto em que a igualdade de oportunidades educacionais foi um fator nesses esforços. Nossa análise da reorganização do CCSD contribui para uma compreensão mais ampla do desenvolvimento de políticas e políticas a nível estadual no contexto educacional contemporâneo. Nesse caso, descobrimos que os legisladores estaduais conquistaram com sucesso a oportunidade de representar o poder e a autoridade necessários para ter um impacto significativo e rápido na estrutura de um dos maiores distritos escolares nos Estados Unidos

What does scalar timing tell us about neural dynamics?

The “Scalar Timing Law,” which is a temporal domain generalization of the well known Weber Law, states that the errors estimating temporal intervals scale linearly with the durations of the intervals. Linear scaling has been studied extensively in human and animal models and holds over several orders of magnitude, though to date there is no agreed upon explanation for its physiological basis. Starting from the assumption that behavioral variability stems from neural variability, this work shows how to derive firing rate functions that are consistent with scalar timing. We show that firing rate functions with a log-power form, and a set of parameters that depend on spike count statistics, can account for scalar timing. Our derivation depends on a linear approximation, but we use simulations to validate the theory and show that log-power firing rate functions result in scalar timing over a large range of times and parameters. Simulation results match the predictions of our model, though our initial formulation results in a slight bias toward overestimation that can be corrected using a simple iterative approach to learn a decision threshold.R01MH093665K99MH09965

The Assessment of the Atherogenic Lipoprotein Profile in Cardiovascular Diseases by Lipoprint System Analysis

Research focus: Identification of incidence of an atherogenic lipoprotein phenotype B in four representative diagnoses of cardiovascular diseases: a) arterial hypertension, b) coronary heart disease, c) lower extremity arterial disease, d) ischemic stroke Research methods: A clinical study included 366 patients with a diagnosis of arterial hypertension (n=107), coronary heart disease (n= 104), lower extremity arterial disease (n= 100) and ischemic stroke (n= 55). The control group consisted of 150 healthy normotensive and normolipemic volunteers, all non-smokers, without signs of cardiovascular disease. In all tested individuals (or subjects) lipid parameters in serum: cholesterol and triglycerides were analyzed, using the enzymatic CHOD-PAP method, Roche Diagnostics Germany. Lipoproteins in serum lipoprotein spectrum by Lipoprint LDL system were analyzed and an atherogenic and a non-atherogenic lipoprotein profile idetified. The Score of the Anti-Atherogenic Risk (SAAR) was calculated as the ratio between non-atherogenic and atherogenic lipoproteins. Results: More than 80 percent of tested patients with cardovascular diseases have an atherogenic lipoprotein profile, with a high level of strongly atherogenic small dense LDL. The atherogenic profile was found in arterial hypertension 78.5%, in coronary heart disease in 81.7%, in lower extremity arterial disease in 80 %, and in patients who survived an ischemic stroke in 85%. Main conclusion: The atherogenic lipoprotein profile was found to be the overwhelming lipoprotein profile in tested cardiovascular diseases A new phenomenon- atherogenic normolipidemia - as a risk factor for the development of cardiovascular disease, would be established as a new term used in the diagnostics of dyslipoproteinemia

Learning and recognition of tactile temporal sequences by mice and humans

The world around us is replete with stimuli that unfold over time. When we hear an auditory stream like music or speech or scan a texture with our fingertip, physical features in the stimulus are concatenated in a particular order. This temporal patterning is critical to interpreting the stimulus. To explore the capacity of mice and humans to learn tactile sequences, we developed a task in which subjects had to recognise a continuous modulated noise sequence delivered to whiskers or fingertips, defined by its temporal patterning over hundreds of milliseconds. GO and NO-GO sequences differed only in that the order of their constituent noise modulation segments was temporally scrambled. Both mice and humans efficiently learned tactile sequences. Mouse sequence recognition depended on detecting transitions in noise amplitude; animals could base their decision on the earliest information available. Humans appeared to use additional cues, including the duration of noise modulation segments