A Practical implementation of high-speed communication using digital subscriber line technology

This thesis creates a plan for the practical implementation of high-speed communication for residences and businesses. By implementing low-cost, high-speed communication on a global scale, tremendous benefits can occur in areas such as Internet communication, interactive multimedia, telecommuting, and distance learning. Despite several successful trials of various high-speed communication technologies, many barriers remain before deployment can occur to the general public. This thesis proposes a plan to bridge the gap between theoretical test studies and global implementation. This thesis evaluates three communication systems as potential solutions for high-speed communication and selects one system as the solution. The three candidate systems are Digital Subscriber Line technologies (collectively referred to as xDSL), Integrated Services Digital Network (ISDN), and cable modem. The chosen technology solution, xDSL, allows twisted-pair copper wire (i.e. telephone lines) to be used for high-speed communication. The choice of xDSL as the technology solution is based on many factors, all of which correspond to practicality. The intent of this thesis is not the promotion of xDSL; rather, the primary objective is to create a plan to quickly and globally implement a low-cost, high-speed communication infrastructure for residences and businesses

Organizational Characteristics of High- and Low-Clozapine-Utilization Clinics in the Veterans Health Administration

Objective: Treatment-resistance schizophrenia occurs in 20-30% of patients. Clozapine is the only medication proven effective for treatment-resistant schizophrenia. However, less than 25% of treatment-resistant schizophrenia patients receive clozapine in most settings. Therefore, this study was conducted to identify facilitators and barriers to clozapine use, to inform development of interventions to maximize appropriate clozapine-utilization. Methods: Seventy semi-structured phone interviews were conducted with five high- and five low-utilization VA Medical Centers, from different US regions including urban and rural areas. Interviewees were key informants of clozapine processes, including mental health leadership, psychiatrists, clinical pharmacists and advanced practice nurses. Interviews were analyzed using an emergent thematic strategy to identify barriers and facilitators to clozapine prescribing. Results: Key elements associated with high-utilization included integration of non-physician psychiatric providers and clear organizational processes and infrastructure for treatment of severe mental illness (e.g. clozapine clinics, larger mental health intensive case management services). Low-utilization was associated with lack of champions to support clozapine processes and limited-capacity care systems. Obstacles identified at both high- and low-utilization sites included complex time-consuming paperwork, reliance on few individuals to facilitate processes, and issues related to transportation for patients living far from care facilities. Conclusions: Implementation efforts to organize, streamline and simplify clozapine processes, development of a multidisciplinary clozapine clinic, increasing the size and capacity of existing clinics, and provision of transportation are reasonable targets to increase clozapine utilization

Early life height and weight production functions with endogenous energy and protein inputs

We examine effects of protein and energy intakes on height and weight growth for children between 6 and 24 months old in Guatemala and the Philippines. Using instrumental variables to control for endogeneity and estimating multiple specifications, we find that protein intake plays an important and positive role in height and weight growth in the 6-24 month period. Energy from other macronutrients, however, does not have a robust relation with these two anthropometric measures. Our estimates indicate that in contexts with substantial child undernutrition, increases in protein-rich food intake in the first 24 months can have important growth effects, which previous studies indicate are related significantly to a range of outcomes over the life cycl

Functional Brain Network Modularity Captures Inter- and Intra-Individual Variation in Working Memory Capacity

Cognitive abilities, such as working memory, differ among people; however, individuals also vary in their own day-to-day cognitive performance. One potential source of cognitive variability may be fluctuations in the functional organization of neural systems. The degree to which the organization of these functional networks is optimized may relate to the effective cognitive functioning of the individual. Here we specifically examine how changes in the organization of large-scale networks measured via resting state functional connectivity MRI and graph theory track changes in working memory capacity.Twenty-two participants performed a test of working memory capacity and then underwent resting-state fMRI. Seventeen subjects repeated the protocol three weeks later. We applied graph theoretic techniques to measure network organization on 34 brain regions of interest (ROI). Network modularity, which measures the level of integration and segregation across sub-networks, and small-worldness, which measures global network connection efficiency, both predicted individual differences in memory capacity; however, only modularity predicted intra-individual variation across the two sessions. Partial correlations controlling for the component of working memory that was stable across sessions revealed that modularity was almost entirely associated with the variability of working memory at each session. Analyses of specific sub-networks and individual circuits were unable to consistently account for working memory capacity variability.The results suggest that the intrinsic functional organization of an a priori defined cognitive control network measured at rest provides substantial information about actual cognitive performance. The association of network modularity to the variability in an individual's working memory capacity suggests that the organization of this network into high connectivity within modules and sparse connections between modules may reflect effective signaling across brain regions, perhaps through the modulation of signal or the suppression of the propagation of noise

Failure of Working Memory Training to Enhance Cognition or Intelligence

Fluid intelligence is important for successful functioning in the modern world, but much evidence suggests that fluid intelligence is largely immutable after childhood. Recently, however, researchers have reported gains in fluid intelligence after multiple sessions of adaptive working memory training in adults. The current study attempted to replicate and expand those results by administering a broad assessment of cognitive abilities and personality traits to young adults who underwent 20 sessions of an adaptive dual n-back working memory training program and comparing their post-training performance on those tests to a matched set of young adults who underwent 20 sessions of an adaptive attentional tracking program. Pre- and post-training measurements of fluid intelligence, standardized intelligence tests, speed of processing, reading skills, and other tests of working memory were assessed. Both training groups exhibited substantial and specific improvements on the trained tasks that persisted for at least 6 months post-training, but no transfer of improvement was observed to any of the non-trained measurements when compared to a third untrained group serving as a passive control. These findings fail to support the idea that adaptive working memory training in healthy young adults enhances working memory capacity in non-trained tasks, fluid intelligence, or other measures of cognitive abilities.National Institutes of Health (U.S.) (Blueprint for Neuroscience Research (T90DA022759/R90DA023427)United States. Defense Advanced Research Projects Agency (government contract no. NBCHC070105)United States. Dept. of Defense (National Defense Science and Engineering Fellowship)Massachusetts Institute of Technology (Sheldon Razin (1959) Fellowship

Neural Mechanisms of Interference Control in Working Memory: Effects of Interference Expectancy and Fluid Intelligence

A critical aspect of executive control is the ability to limit the adverse effects of interference. Previous studies have shown activation of left ventrolateral prefrontal cortex after the onset of interference, suggesting that interference may be resolved in a reactive manner. However, we suggest that interference control may also operate in a proactive manner to prevent effects of interference. The current study investigated the temporal dynamics of interference control by varying two factors - interference expectancy and fluid intelligence (gF) - that could influence whether interference control operates proactively versus reactively.A modified version of the recent negatives task was utilized. Interference expectancy was manipulated across task blocks by changing the proportion of recent negative (interference) trials versus recent positive (facilitation) trials. Furthermore, we explored whether gF affected the tendency to utilize specific interference control mechanisms. When interference expectancy was low, activity in lateral prefrontal cortex replicated prior results showing a reactive control pattern (i.e., interference-sensitivity during probe period). In contrast, when interference expectancy was high, bilateral prefrontal cortex activation was more indicative of proactive control mechanisms (interference-related effects prior to the probe period). Additional results suggested that the proactive control pattern was more evident in high gF individuals, whereas the reactive control pattern was more evident in low gF individuals.The results suggest the presence of two neural mechanisms of interference control, with the differential expression of these mechanisms modulated by both experimental (e.g., expectancy effects) and individual difference (e.g., gF) factors

Positron Emission Tomography Imaging of CD105 Expression with a 64Cu-Labeled Monoclonal Antibody: NOTA Is Superior to DOTA

Optimizing the in vivo stability of positron emission tomography (PET) tracers is of critical importance to cancer diagnosis. In the case of 64Cu-labeled monoclonal antibodies (mAb), in vivo behavior and biodistribution is critically dependent on the performance of the bifunctional chelator used to conjugate the mAb to the radiolabel. This study compared the in vivo characteristics of 64Cu-labeled TRC105 (a chimeric mAb that binds to both human and murine CD105), through two commonly used chelators: 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). Flow cytometry analysis confirmed that chelator conjugation of TRC105 did not affect its CD105 binding affinity or specificity. PET imaging and biodistribution studies in 4T1 murine breast tumor-bearing mice revealed that 64Cu-NOTA-TRC105 exhibited better stability than 64Cu-DOTA-TRC105 in vivo, which resulted in significantly lower liver uptake without compromising the tumor targeting efficiency. In conclusion, this study confirmed that NOTA is a superior chelator to DOTA for PET imaging with 64Cu-labeled TRC105