Classification of Types of Stuttering Symptoms Based on Brain Activity

Among the non-fluencies seen in speech, some are more typical (MT) of stuttering speakers, whereas others are less typical (LT) and are common to both stuttering and fluent speakers. No neuroimaging work has evaluated the neural basis for grouping these symptom types. Another long-debated issue is which type (LT, MT) whole-word repetitions (WWR) should be placed in. In this study, a sentence completion task was performed by twenty stuttering patients who were scanned using an event-related design. This task elicited stuttering in these patients. Each stuttered trial from each patient was sorted into the MT or LT types with WWR put aside. Pattern classification was employed to train a patient-specific single trial model to automatically classify each trial as MT or LT using the corresponding fMRI data. This model was then validated by using test data that were independent of the training data. In a subsequent analysis, the classification model, just established, was used to determine which type the WWR should be placed in. The results showed that the LT and the MT could be separated with high accuracy based on their brain activity. The brain regions that made most contribution to the separation of the types were: the left inferior frontal cortex and bilateral precuneus, both of which showed higher activity in the MT than in the LT; and the left putamen and right cerebellum which showed the opposite activity pattern. The results also showed that the brain activity for WWR was more similar to that of the LT and fluent speech than to that of the MT. These findings provide a neurological basis for separating the MT and the LT types, and support the widely-used MT/LT symptom grouping scheme. In addition, WWR play a similar role as the LT, and thus should be placed in the LT type

CHEMICAL STATE ANALYSIS OF NITRIDED STEEL SURFACE BY MEANS OF CONVERSION ELECTRON MÖSSBAUER SPECTROMETRY

La spectroscopie Mössbauer d'électrons de conversion a été employée pour caractériser des surfaces d'acier nitruré ; l'état chimique des surfaces a été analysé couche par couche. La surface d'acier nitruré par réaction avec l'azote est composée de Fe2N-ε, Fe3-XN(0≤x≤1) distordu, de la martensite Fe4N-γ et d'une couche de fer-α légèrement déformé par l'azote introduit. La nitruration par attaque chimique conduit à une surface de Fe3N-ε, des couches intermédiaires de Fe3N-ε et Fe4N-γ' et du Fe-α distordu. La couche nitrurée par électrochimie a une épaisseur de 2 à 3 microns de Fe4N-γ'1, Fe4N-γ'2 et des couches de Fe-α distordu.CEMS was used to characterize the nitrided steel surfaces and chemical states of surfaces estimated layer by layer. Gas nitrided steel surface is composed of ε-Fe2N, distorted Fe3+xN (0≤x≤1), γ'-Fe4N martensite and α-Fe layer slightly disturbed by intruded nitrogen. Tufftrided steel surface consists of ε-Fe3N, intermediate ε-Fe3N and γ'-Fe4N, γ'-Fe4N and disturbed α-Fe layers. Ion nitrided steel surface has a 2~3 µm thickness of γ'2-Fe4N (magnetically randomly oriented), γ'2-Fe4N and distorted α-Fe layers

Combination of electrochemical hydrogenation and Mössbauer spectroscopy as a tool to show the radiation effect of energetic heavy ions in Fe-Zr amorphous alloys

Abstract Radiation effects of energetic heavy ion irradiation in Fe-Zr amorphous alloys were investigated by the help of Mossbauer spectroscopy, X-ray diffraction and electrolytical hydrogenation. The electrolytical hydrogenation of non-irradiated and irradiated samples was carried out by a unique cathodic potential (y1000 mV versus SHE). The combination of electrolytical hydrogenation and Mossbauer analysis gives ä very sensitive method for detecting structural changes of these amorphous alloys. It was found that the structural changes in the amorphous state, which are undetectable without hydrogenation by Mossbauer spectroscopy, modify the localization and the concentration of introduced hydrogen, and are reflected in a significant change of magnetic hyperfine interaction. The results can be associated with structural changes due to the effect of energetic heavy ion irradiation. q2000 Elsevier Science S.A. All rights reserved

Iron nitride and carbonitride phases in a nitrogen implanted carbon steel

Iron nitride and carbonitride phases formed during nitrogen implantation and subsequent thermal annealing of a medium-carbon steel are investigated by means of conversion electron Mossbauer scattering. The results are compared to previous work on similar systems and also discussed in terms of the mechanical properties of ion implanted steels