Neuroimaging investigation of the motor control disorder, dystonia with special emphasis on laryngeal dystonia

Thesis (Ph. D. in Speech and Hearing Bioscience and Technology)--Harvard-MIT Program in Health Sciences and Technology, 2013.Cataloged from PDF version of thesis.Includes bibliographical references.Laryngeal dystonia (LD) is the focal laryngeal form of the neurological movement disorder called dystonia, a condition that often changes in severity depending on the posture assumed and on voluntary activity of the affected body area. Pathophysiology of dystonia is unknown. This thesis employed a combination of diffusion tensor and functional magnetic resonance imaging (DTI and fMRI) studies to investigate the structure and function of the basal ganglia (BG) in dystonia patients. Fractional anisotropy (FA) and probabilistic diffusion tractography analyses were used to investigate the questions of whether LD patients exhibited altered connectivity between BG and brainstem regions and whether FA and tractography could be used to predict differences in clinical presentations of dystonia. Findings of this study support the hypothesis that connections between the BG and brainstem may play a role in dystonia pathophysiology and may be used to predict differences in clinical presentations of dystonia. An fMRI study was carried out to investigate whether abnormally sustained BG activity observed after performance of a finger tapping task in hand dystonia patients may represent an amplification of a normal motor control mechanism. As dystonia has been hypothesized to result from overactivation of normal postural programs, this study aimed to investigate the question of whether the sustained BG activity was a normal feature observed in motor control tasks requiring more precision. Results suggest that cerebellar cortex is recruited particularly during fine motor control.by Miriam L. Makhlouf.Ph.D.in Speech and Hearing Bioscience and Technolog

Salinity effects on germination, growth and mineral nutrition of Ricinus communis seedlings

The salinity effects on the germination and the growth of greenhouse grown castor bean (Ricinus communis L.) from three local provenances (Sidi Thabet, Grombalia and Kairouan) were studied. Plants were grown in sand-perlite mixture and irrigated with solution containing 0, 2, 5, and 10 g/l NaCl. The effect of salt stress on germination was weakly pronounced in the case of castor bean for the three provenances compared to control. Moreover, salt stress induced significant differences on plant growth during the experimental period. After 80 stress days, decreases in plant height were observed. 10 g/l NaCl has an intense depressive effect on seedling stage. The seedlings have not completed their development and this is noticed for all provenances. 5 g/l NaCl has also an intense depressive effect only for Grombalia. With regards to the mineral nutrition, hypocotyls are more concentrated in Na+ and Cl− than the other organs. Thus, we observed a slight increase in K+ concentration for 2 and 5 g/l NaCl compared to control, especially for Kairouan in stems. Based on the stability of the tolerance to salinity from germinative stage to seedlings stage, the provenance of Kai rouan was identified as the most tolerant and the provenance of Grombalia as the most sensitive to salt toxicity

Family, Gender, and Population Policy: Views from the Middle East [Arabic]

This paper explores the relevance of international debates to the realities of the Middle East, an important but understudied region that has often been subject to stereotyping. The region’s wealth of traditions and diverse contemporary experience offer insights to those who venture beyond the surface appearance. This paper provides a broad introduction to the connections between family, gender, and population policy in the Middle East. It is based on studies by a diverse group of Middle East scholars and the discussions they generated in Cairo at an international symposium sponsored by the Population Council in February 1994. The paper was written prior to the historic UN International Conference on Population and Development in Egypt, in the hope both of increasing understanding of an important region of the world and refining our grasp of international issues

Predicting compositions and properties of aluminum die casting alloys using artificial neural network

Despite the large number of existing alloys and alloy databases, identifying proper alloys for specific applications still remains a challenge. In order to facilitate the selection and prediction of aluminum die casting alloys and their properties, an electronic database - ?i-Select-Al? - has been developed by the Advanced Casting Research Center (ACRC) and the North American Die Casting Association (NADCA). The key to the predictions is the determination of a relationship between alloy properties, chemical composition, and processing variables. Theoretically, these relationships can be ?accurately? determined using fundamental physical principles. However, in practice, the underlying mechanisms are not fully understood and difficult to be utilized. In this case, approximate empirical models are considered. In version 1.0 of the software trend equations have been generated. The nature of these trend equations limits the applicability and prediction ability of the software. In order to improve the prediction power; relationships based on an artificial neural network (ANN) were exploited in version 2.0. ANN has proven to be a highly flexible tool, suitable to treat multiple-input conditions and nonlinear phenomena with complex relationships between input and output variables. This article presents the working mechanisms, the programming, and the application of ANN in this project. The results show that ANN is a valuable modelling tool for predicting properties- fromcomposition and composition- from-properties for aluminum die casting alloys

Relaxation and Landau-Zener experiments down to 100 mK in ferritin

Temperature-independent magnetic viscosity in ferritin has been observed from 2 K down to 100 mK, proving that quantum tunneling plays the main role in these particles at low temperature. Magnetic relaxation has also been studied using the Landau-Zener method making the system crossing zero resonant field at different rates, alpha=dH/dt, ranging from 10^{-5} to 10^{-3} T/s, and at different temperatures, from 150 mK up to the blocking temperature. We propose a new Tln(Delta H_{eff}/tau_0 alpha) scaling law for the Landau-Zener probability in a system distributed in volumes, where Delta H_{eff} is the effective width of the zero field resonance.Comment: 13 pages, 4 postscript figure

Hom-quantum groups I: quasi-triangular Hom-bialgebras

We introduce a Hom-type generalization of quantum groups, called quasi-triangular Hom-bialgebras. They are non-associative and non-coassociative analogues of Drinfel'd's quasi-triangular bialgebras, in which the non-(co)associativity is controlled by a twisting map. A family of quasi-triangular Hom-bialgebras can be constructed from any quasi-triangular bialgebra, such as Drinfel'd's quantum enveloping algebras. Each quasi-triangular Hom-bialgebra comes with a solution of the quantum Hom-Yang-Baxter equation, which is a non-associative version of the quantum Yang-Baxter equation. Solutions of the Hom-Yang-Baxter equation can be obtained from modules of suitable quasi-triangular Hom-bialgebras.Comment: 21 page

Crystal structure of the catalytic D2 domain of the AAA+ ATPase p97 reveals a putative helical split-washer-type mechanism for substrate unfolding

Several pathologies have been associated with the AAA+ ATPase p97, an enzyme essential to protein homeostasis. Heterozygous polymorphisms in p97 have been shown to cause neurological disease, while elevated proteotoxic stress in tumours has made p97 an attractive cancer chemotherapy target. The cellular processes reliant on p97 are well described. High‐resolution structural models of its catalytic D2 domain, however, have proved elusive, as has the mechanism by which p97 converts the energy from ATP hydrolysis into mechanical force to unfold protein substrates. Here, we describe the high‐resolution structure of the p97 D2 ATPase domain. This crystal system constitutes a valuable tool for p97 inhibitor development and identifies a potentially druggable pocket in the D2 domain. In addition, its P61 symmetry suggests a mechanism for substrate unfolding by p97