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Sickle cell disease (SCD) is a chronic blood disorder that is often associated with acute and chronic cerebrovascular complications, including strokes and impaired cognition. Using functional resting state magnetic resonance images, we performed whole-brain analysis of the amplitude of low frequency fluctuations (ALFF), to detect areas of spontaneous blood oxygenation level dependent signal across brain regions. We compared the ALFF of 20 SCD patients to that observed in 19 healthy, age and ethnicity-matched, control subjects. Significant differences were found in several brain regions, including the insula, precuneus, anterior cingulate cortex and medial superior frontal gyrus. To identify the ALFF differences resulting from anemia alone, we also compared the ALFF of SCD patients to that observed in 12 patients having comparable hemoglobin levels but lacking sickle hemoglobin. Increased ALFF in the orbitofrontal cortex and the anterior and posterior cingulate cortex and decreased ALFF in the frontal pole, cerebellum and medial superior frontal gyrus persisted after accounting for the effect of anemia. The presence of white matter hyperintensities was associated with depressed frontal and medial superior frontal gyri activity in the SCD subjects. Decreased ALFF in the frontal lobe was correlated with decreased verbal fluency and cognitive flexibility. These findings may lead to a better understanding of the pathophysiology of SCD.

Sickle cell disease is an inherited blood disorder characterized by vasoocclusive crises. Although hypoxia and pulmonary disease are known risk factors for these crises, the mechanisms that initiate vasoocclusive events are not well known. To study the relationship between transient hypoxia, respiration, and microvascular blood flow in patients with sickle cell. We established a protocol that mimics nighttime hypoxic episodes and measured microvascular blood flow to determine if transient hypoxia causes a decrease in microvascular blood flow. Significant desaturations were induced safely by five breaths of 100% nitrogen. Desaturation did not induce change in microvascular perfusion; however, it induced substantial transient parasympathetic activity withdrawal in patients with sickle cell disease, but not controls subjects. Marked periodic drops in peripheral microvascular perfusion, unrelated to hypoxia, were triggered by sighs in 11 of 11 patients with sickle cell and 8 of 11 control subjects. Although the sigh frequency was the same in both groups, the probability of a sigh inducing a perfusion drop was 78% in patients with sickle cell and 17% in control subjects (P < 0.001). Evidence for sigh-induced sympathetic nervous system dominance was seen in patients with sickle cell (P < 0.05), but was not significant in control subjects. These data demonstrate significant disruption of autonomic nervous system balance, with marked parasympathetic withdrawal in response to transient hypoxia. They draw attention to an enhanced autonomic nervous system–mediated sigh–vasoconstrictor response in patients with sickle cell that could increase red cell retention in the microvasculature, promoting vasoocclusion.

This thesis explores MRI measurements of cerebral oxygen supply and demand in subjects with sickle cell disease. I hypothesize that uncoupling of cerebral oxygen supply and demand occurs in patients with sickle cell disease due to pathophysiology. To test this hypothesis, this thesis goes on to validate MR cerebral oxygen supply and demand methods including Phase Contrast, Arterial Spin Labeling and T2 Relaxation Under Spin Tagging.

Carpio et al talk about the approach in creating Building People's Histories. In opposition to common misconceptions of history as a textbook-driven trivial pursuit of names and dates, popular approaches to people's history frame history as a constant human struggle and involve thought, feeling, and individual and collective action to guide social change. The intellectual task of creating historical narratives and the pedagogical task of engaging students in this process become integral parts of contemporary social struggles to strengthen democratic institutions and cultures.

Sickle cell disease (SCD) is characterized by sudden onset of painful vaso‐occlusive crises (VOC), which occur on top of the underlying chronic blood disorder. The mechanisms that trigger VOC remain elusive, but recent work suggests that autonomic dysfunction may be an important predisposing factor. Heart‐rate variability has been employed in previous studies, but the derived indices have provided only limited univariate information about autonomic cardiovascular control in SCD. To circumvent this limitation, a time‐varying modeling approach was applied to investigate the functional mechanisms relating blood pressure (BP) and respiration to heart rate and peripheral vascular resistance in healthy controls, untreated SCD subjects and SCD subjects undergoing chronic transfusion therapy. Measurements of respiration, heart rate, continuous noninvasive BP and peripheral vascular resistance were made before, during and after the application of cold face stimulation (CFS), which perturbs both the parasympathetic and sympathetic nervous systems. Cardiac baroreflex sensitivity estimated from the model was found to be impaired in nontransfused SCD subjects, but partially restored in SCD subjects undergoing transfusion therapy. Respiratory‐cardiac coupling gain was decreased in SCD and remained unchanged by chronic transfusion. These results are consistent with autonomic dysfunction in the form of impaired parasympathetic control and sympathetic overactivity. As well, CFS led to a significant reduction in vascular resistance baroreflex sensitivity in the nontransfused SCD subjects but not in the other groups. This blunting of the baroreflex control of peripheral vascular resistance during elevated sympathetic drive could be a potential factor contributing to the triggering of VOC in SCD. This study investigated the effect of cold face stimulation (CFS) on autonomic function in subjects with sickle cell disease (SCD), chronically transfused SCD subjects, and healthy controls. Using a time‐varying computational model, we found that cardiac baroreflex sensitivity was impaired in nontransfused SCD subjects, but partially restored toward healthy control levels in SCD subjects undergoing transfusion therapy. As well, CFS reduced vascular resistance baroreflex sensitivity in the nontransfused SCD subjects but not in the other groups.

Passing Notes in Class revises common narratives of jazz history through an examination of the origins of institutionalized jazz education. In the early 20th century, as segregated Black public schools grew, students began to demand a place for Black culture and history in the school curriculum. Moving away from music programs that focused upon choirs and spirituals, music teachers soon established strong instrumental classes that focused upon Black popular music. Too many histories of this music have positioned improvisation as something innate to the musician, the environment, or the culture and performance as isolated, spontaneous incidents. The music programs discussed here, primarily in Los Angeles, Birmingham, Chicago, and Oklahoma City, established some of the first state sponsored jazz practice sessions and, in doing so, laid fertile ground for the development of generations of Black musicians and others who used the principles of improvisation in a number of career paths. While focusing specifically on the stories of Zelia N. Breaux, John ‘Fess Whatley, Samuel R. Browne, and Capt. Walter H. Dyett, through oral histories of students, musicians, and community leaders, this dissertation listens to music history through relationships, not performance. By examining these classrooms, this dissertation positions pedagogical relationships and the community formations that developed out of them as the basis for any performance, and places these performances as just one aspect in the sound, culture, and history of jazz. The chapters focus on moments of institutionalization of musical instruction within Black high schools in various cities throughout America and use these moments as windows into the role of migration, student activism, community arts, urban planning, and multi-ethnic collaboration in jazz history and the history of the United States. “Pedagogical Improvisations” discussed within this dissertation refer to strategies that teachers employed to navigate the social conditions of music making and instruction in these institutions. By studying networks of community and apprenticeship within these various regions, this dissertation offers something akin to a territorial history of jazz, as well as an original framework for documenting and understanding the evolution of modern Black music. Challenging the idea that jazz is created and passed down on the bandstand, the recording studio, and the tour bus, “Passing Notes” explores how communities are formed and knowledges are passed down generationally. They are stories of how Black community leaders throughout America created musical institutions that managed to teach what were—and imagine what might be—new possibilities to simultaneously migrate and remain at home. In a sense, jazz has always vacillated between claiming (and being claimed by) its roots and its rootless-ness: it is a music of motion, of improvisation, of being “always complete and never finished,” as much as it is a music that reflects the unique conditions of urban culture in which it was born.

We propose multiMap, a single scan that can generate several quantitative maps simultaneously. The sequence acquires multiple images in a time-efficient manner, which can be modeled for T_2, T2*, main- and transmit-field inhomogeneity, T_1:equilibrium magnetization, and water and fat content. The sequence is constructed so that cross-dependencies between parameters are isolated. Thus, each parameter can be estimated independently. Estimates of all parameters are shown on bottle phantoms, the brain, and the knee. The results are compared to estimates from established techniques.

On top of all this, what about the students who are new and have a hard time fitting in? Are they supposed to sit there, without friends, until they get the courage to walk up to a total stranger and ask them \"Hey what's up?\" when they could join a school- oriented club in which they can associate themselves much more easily?