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Les attaques par canaux cachés sont une forme d'attaque particulièrement dangereuse. Dans cette thèse, nous nous intéressons au canal caché temporel. Un programme est dit ''constant-time'' lorsqu'il n'est pas vulnérable aux attaques par canal caché temporel. Nous présentons dans ce manuscrit deux méthodes reposant sur l'analyse statique afin de s'assurer qu'un programme est constant-time. Ces méthodes se placent dans le cadre de vérification formelle afin d'obtenir le plus haut niveau d'assurance possible en s'appuyant sur une chaîne de compilation vérifiée composée du compilateur CompCert et de l'analyseur statique Verasco. Nous proposons aussi une méthode de preuve afin de s'assurer qu'un compilateur préserve la propriété de constant-time lors de la compilation d'un programme. / Side-channel attacks are an especially dangerous form of attack. In this thesis, we focus on the timing side-channel. A program is said to be constant-time if it is not vulnerable to timing attacks. We present in this thesis two methods relying on static analysis in order to ensure that a program is constant-time. These methods use formal verification in order to gain the highest possible level of assurance by relying on a verified compilation toolchain made up of the CompCert compiler and the Verasco static analyzer. We also propose a proof methodology in order to ensure that a compiler preserves constant-time security during compilation.

The purpose of the study was to evaluate the use of a constant time delay procedure to teach core content words in braille to a student with a visual impairment. A multiple probe (conditions) across behaviors design was used to evaluate the effectiveness of the training and follow-up sessions. The results showed the procedure was effective in teaching core content braille words within a resource setting and the student was able to generalize the information to an inclusive setting.

This study examined the fidelity of implementation by four Head Start teachers using the teaching strategies of constant time delay, enhanced milieu teaching, and system of least prompts with children with and without disabilities in an inclusive early childhood setting. The teachers worked with the researcher to determine appropriate skills to target for each teaching strategy. A multiple probe across behaviors design replicated across four teachers was used to determine the effects of teachers’ fidelity of implementation of evidence-based teaching strategies. The results showed that Head Start teachers could implement systematic teaching strategies with fidelity. The study also examined if children with and without disabilities can make progress towards their target skills. The results showed that children were able to make progress towards their target skills.

Constant time delay (CTD) and progressive time delay (PTD) are both evidence-based practices used to teach students with intellectual disability (ID). The prompt delay strategies have been used for instruction with academics, social, vocational, and communication skills. There is limited research regarding the differential effectiveness of the time delay variations for teaching academic content to students with ID. The present study compares the effects of CTD and PTD in the acquisition of academic content with four students with ID. An adapted alternating treatments design was used to compare the effectiveness and efficiency of the two procedures. Generalization was assessed across settings, participants, and materials. Results indicated that both strategies were effective but PTD was more efficient in regards to number of errors and average time to criterion.

The purpose of this study was to determine the impact of using preferred characters with a constant time delay instructional procedure to teach community sign reading to three students with moderate intellectual disability with the definitions of the signs as non-targeted information. An adapted alternating treatments design was used to evaluate the effectiveness and efficiency of the preferred characters on acquisition of the community signs. Pre- and post- assessments were conducted on acquisition of the non-targeted definitions, as well as generalization of the signs and their meanings. The results indicated that all students learned the target signs and they learned all of the definitions of the signs when they were presented with a preferred character. Students did not generalize the meanings of the signs to community settings.

GPUs (Graphics Processing Units) employ a multi-threaded execution model using multiple SIMD cores. Compared to use of a single SIMD engine, this architecture can scale to more processing elements. However, GPUs sacrifice the timing properties which made barrier synchronization implicit and collective communication operations fast. This thesis demonstrates efficient methods by which these aggregate functions can be implemented using unmodified NVIDIA CUDA GPUs. Although NVIDIA's highest “compute capability" GPUs provide atomic memory functions, they have order N execution time. In contrast, the methods proposed here take advantage of basic properties of the GPU architecture to make implementations that are both efficient and portable to all CUDA-capable GPUs. A variety of coordination operations are synthesized, and the algorithm, CUDA code, and performance of each are discussed in detail.

Five elementary age students with moderate to severe intellectual disabilities were taught shape identification. A multiple probe design across behaviors, replicated across participants, was used to determine the effectiveness of constant time delay to determine the effectiveness of Constant Time Delay to teach shapes. Nontarget information was included in praise statements. All students met criterion on target information of shape identification. All students increased their ability to identify shape words, spell shape words, tell the number of sides of the shapes when presented and tell the number of angles of shapes presented. Generalization occurred during daily walks through the school and community as well as during the probe sessions.

abstract: This study compared a stimulus fading (SF) procedure with a constant time delay (CTD) procedure for identification of consonant-vowel-consonant (CVC) nonsense words for a participant with autism. An alternating treatments design was utilized through a computer-based format. Receptive identification of target words was evaluated using a computer format and the researcher conducted a generalization probe for expressive identification evaluation. Neither treatment condition resulted in consistent gains on the receptive identification measure. Both treatment conditions resulted in gains on the expressive identification assessment. The SF treatment condition was more efficient due to 1) accuracy in identifying all of the SF target words in fewer sessions than the CTD target words and 2) incidental learning that occurred as a result of exposure to additional SF words as distracter choices and in receptive identification assessments. Implications are discussed. / Dissertation/Thesis / Ph.D. Special Education 2011

Very little research has occurred about students with severe disabilities and verbal difficulties and their ability to learn phonics, decoding, and other early literacy skills(Ainsworth et al., 2016 and Johnston et al., 2009b). Ainsworth et al. (2016) used the Accessible Literacy Learning curriculum to teach phonics and decoding. Johnston et al. (2009b) used a three-step instructional strategy, step one - increased opportunities for adult-directed teaching and active teacher child interaction, step two- use of time delay to teach, step three-consequences, to teach phonics and decoding. While both studies utilized time delay in some fashion, they were not entirely based upon the evidence-based practice. Therefore, the purpose of this study is to determine whether constant time delay is effective in teaching phonics and decoding to students with severe disabilities and verbal difficulties and if students can generalize the skill to words that have not been explicitly taught. Results indicated a functional relation between the use of constant time delay and decoding of CVC words. Additionally, students were able to maintain and generalize learning. Students with severe disabilities and verbal difficulties can effectively learn decoding of CVC words through constant time delay and can maintain and generalize the skill. Results were similar to other studies which implemented constant time delay to promote emergent literacy skills (e.g., Browder et al., 2012; Dessemont et al., 2019; Spooner et al., 2015; Tucker Cohen et al., 2008). Practitioners can use constant time delay to teach decoding to students with severe disabilities and verbal difficulties and to promote early reading skills. Future research should replicate the study with students from different age groups as well as examining the effects of this strategy on the acquisition of CCVC and CVCC words.