Preventive effect of vitamin B6 on developmental toxicity of carbamazepine in mice

Objective(s): Carbamazepine (CBZ) is an antiepileptic drug that is used widely for the treatment of epileptic seizures. Neural tube defects (NTDs), growth retardation, and nail hypoplasia are the most common features of teratogenic effects of this drug. The purpose of this study was to examine the effect of vitamin B6 on the developmental toxicity of CBZ on mice. Materials and Methods: Sixty BALB/c pregnant mice were divided into four experimental and two control groups. Two experimental groups received daily intraperitoneal injection (IP) of 30 mg/kg (I) or 60 mg/kg (II) of CBZ on gestational days (GD) 6 to 15. Two other experimental groups received daily IP injection of 30 mg/kg (III) or 60 mg/kg (IV) of CBZ with 10 mg/kg/day vitamin B6 by gavage 10 days prior to gestation and on GD 6 to 15. Two control groups received normal saline or Tween 20. Dams underwent Cesarean section on GD 18 and embryos were harvested. External/macroscopic observation of fetuses was done by stereomicroscope and external examination for malformations was recorded. Data analyzed by ANOVA and X 2 test using SPSS software. Results: The mean weight and crown-rump of the fetuses in both CBZ-treated experimental groups were significantly reduced compared with those of the control groups. Various malformations were detected such as brachygnathia, eye malformations, NTDs, vertebral deformity, brachydactyly and growth retardation. Vitamin B6 treatment significantly reduced various CBZ-induced malformations. Conclusion: This study showed that vitamin B6 has a preventive effect on the developmental toxicity of CBZ in mice that can be pursued further for clinical research

Developing FPGA-based Embedded Controllers Using Matlab/Simulink

Field Programmable Gate Arrays (FPGAs) are emerging as suitable platforms for implementing embedded control systems. FPGAs offer advantages such as high performance and concurrent computing which makes them attractive in many embedded applications. As reconfigurable devices, they can be used to build the hardware and software components of an embedded system on a single chip. Traditional FPGA design flows and tools, requiring the use of Hardware Description Languages (HDLs), are in a different domain than standard control system design tools such as MATLAB/Simulink. This paper illustrates development of FPGA-based controllers by utilizing popular tools such as MATLAB/Simulink available for the design and development of control systems. The capability of DSP Builder is extended by developing a custom library of control system building blocks that facilitates rapid development of FPGA-based controllers in the familiar Matlab/Simulink environment. As a case study, this paper presents how the tools can be utilized to develop a FPGA-based controller for a laboratory scale air levitation system

Performance Characteristics of Switched Reluctance Motor Drive

In this report, methods and computational techniques for predicting the static and steady state characteristics of a switched reluctance motor drive are developed and the predicted characteristics are compared with experimental results. Because of high local saturation and narrow airgap in the SR motor, accurate calculation of the static characteristics of the torque, flux linkage, inductances, and speed emf from its FE field solution is not straightforward. For the purpose of this study, a two-dimensional finite element model is developed to handle the nonlinear magnetic field inside the machine. Based on a thorough study of the potential sources of errors in the field solution and in the computational methods used in postprocessing, new guidelines are developed regarding the shape and uniformity of the mesh in the airgap and the preservation of these qualities of the mesh as the rotor is rotated. When the proposed guidelines on the mesh configuration and its rotation were used, significant improvement in the accuracy of the field distribution and in the accuracy of the predicted torque/angle characteristics as compared to the experimentally measured torque was observed. Furthermore, all three methods of torque calculation, namely global virtual work, local virtual work, and Maxwell-stress tensor methods are converging to the same results and the torque/angle characteristics are smooth. Improvement in the prediction of such static characteristics is also essential to a realistic prediction of the steady state behavior. In the study of steady state performance of the SRM drive, the converter is approximated by a controlled, square wave pulse generator. In the integration process, the coefficients of the governing differential equation, being dependent on the phase current and rotor angle, are updated using surface interpolation method on the static characteristics. The predicted steady state characteristics compare favorably with the experimental results over a wide range of torque/speed variation

Some Design Calculations for a 60kW, 6000 rpm, 4/6 SRM

This report contains results from a finite element study of the SR machine whose dimensions were provided by Mr Lewis Unnewehr of Sullair Corporation. The objective of the study is to determine the static and steady-state operational characteristics of a given machine design to see if it meets certain design specifications. The study made use of a two-dimension, finite element program that has been developed and described in [1-3]. The same set of references also contained information on the simulation methods and types of control used in this study. Part I of this report presents the basic input data used in this study. The iron parts, including that of the shaft, are assumed to have the magnetic characteristics of M19 steel. The current distribution in the stator coils is assumed to be uniform. Part II contains the results from the FEM calculations: included in here are static characteristics of the flux distribution at several rotor positions, and computed profiles of the flux linkages, the induced emf, and the static torque as a function of rotor position for a range of current excitation. These static characteristics are for the base case design given in Table 1 and are obtained with only one stator phase energized at a time. Part III of the report contains results from sensitivity studies to determine the effects of variations in the airgap, in the relative width of the stator to rotor poles, in the shape of rotor poles, and in the skewing of the rotor poles. Unless otherwise stated the curves and data presented in this report are for the base case dimensions given in Table 1. Sensitivity analysis on airgap length, pole shape, and pole width have been obtained by making the appropriate changes on the rotor pole, the stator dimensions remained the same as those given in Table 1. Also presented are a set of static characteristics for a machine with a smaller airgap length of 0.5 mm. Finally, Part IV of report contains steady-state operational characteristics of the stator current and shaft torque of the machine operating in the current- and angle-control modes as predicted from a steady state simulation assuming a constant input dc voltage. In the steady state simulation the electrical condition of the machine and its torque output are modeled by the appropriate flux linkage, induced emf, and developed torque profiles given in Part II. At the end of the report is a brief discussion on some of the effects that we have studied, and the conclusion that the basic design, with standard angle and current controls, appears to be capable of delivering the desired torque

Teratogenic effects of gabapentin on the skeletal system of Balb/C mice fetuses

Objectives: To evaluate the effects of gabapentin )GBP( administration on mice fetuses. Methods: This study was carried out in Birjand University of Medical Sciences during 2008. Thirty Balb/c pregnant mice were divided randomly into 3 groups: 2 experimental groups that received 25 mg/kg )I( and 50 mg/kg )II( of GBP intraperitoneally for the first 15 days of pregnancy, and a control group that received normal saline. External observations of day 18 fetuses and skeleton double staining were performed. Results: Both experimental groups showed similar disorders that can be categorized as the following: 1( decrease of fetal body weight and increase of fetal resorption, 2( macroscopic malformations, and 3( skeletal malformations. Fetal body weights were significantly lower, and fetus resorptions were significantly higher in both treated groups compared to the control group. Macroscopic malformations included exencephaly, limbs defects, brachygnathia, vertebral column deformity, and fetuses with severe retarded growth. Skeletal malformations included delayed ossification, scoliosis, calvaria deformity, and mandibular hypoplasia. Conclusion: This study revealed that GBP can induce previously unreported severe malformations if it is used continuously during the implantation, neurulation, and organogenesis stages of pregnancy. Therefore, it is suggested that great caution should be exercised in using GBP during the early stages of pregnancy until further studies are performed to better understand these effects

Articulatory feature encoding and sensorimotor training for tactually supplemented speech reception by the hearing-impaired

Thesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 150-159).This thesis builds on previous efforts to develop tactile speech-reception aids for the hearing-impaired. Whereas conventional hearing aids mainly amplify acoustic signals, tactile speech aids convert acoustic information into a form perceptible via the sense of touch. By facilitating visual speechreading and providing sensory feedback for vocal control, tactile speech aids may substantially enhance speech communication abilities in the absence of useful hearing. Research for this thesis consisted of several lines of work. First, tactual detection and temporal order discrimination by congenitally deaf adults were examined, in order to assess the practicability of encoding acoustic speech information as temporal relationships among tactual stimuli. Temporal resolution among most congenitally deaf subjects was deemed adequate for reception of tactually-encoded speech cues. Tactual offset-order discrimination thresholds substantially exceeded those measured for onset-order, underscoring fundamental differences between stimulus masking dynamics in the somatosensory and auditory systems. Next, a tactual speech transduction scheme was designed with the aim of extending the amount of articulatory information conveyed by an earlier vocoder-type tactile speech display strategy. The novel transduction scheme derives relative amplitude cues from three frequency-filtered speech bands, preserving the cross-channel timing information required for consonant voicing discriminations, while retaining low-frequency modulations that distinguish voiced and aperiodic signal components. Additionally, a sensorimotor training approach ("directed babbling") was developed with the goal of facilitating tactile speech acquisition through frequent vocal imitation of visuo-tactile speech stimuli and attention to tactual feedback from one's own vocalizations. A final study evaluated the utility of the tactile speech display in resolving ambiguities among visually presented consonants, following either standard or enhanced sensorimotor training. Profoundly deaf and normal-hearing participants trained to exploit tactually-presented acoustic information in conjunction with visual speechreading to facilitate consonant identification in the absence of semantic context. Results indicate that the present transduction scheme can enhance reception of consonant manner and voicing information and facilitate identification of syllableinitial and syllable-final consonants. The sensorimotor training strategy proved selectively advantageous for subjects demonstrating more gradual tactual speech acquisition. Simple, low-cost tactile devices may prove suitable for widespread distribution in developing countries, where hearing aids and cochlear implants remain unaffordable for most severely and profoundly deaf individuals. They have the potential to enhance verbal communication with minimal need for clinical intervention.by Theodore M. Moallem.Ph.D

Friction Hysteresis Modeling and Force Control in a Constrained Single-link Arm 1

In this paper, we study friction characteristics of a constrained planar single-link arm in applications, where control of the end-point interaction force is required. The objective is to improve performance of a force control system by developing an adequate friction model. It is shown that hub friction increases with the applied force with the end-point force exhibiting significant hysteresis behavior. A friction model is presented for capturing these phenomena and compared with the widely used LuGre friction model. Effectiveness of the proposed model for friction compensation is further examined on an experimental force control system testbed

Iteratively Weighted Centroiding for Shack-Hartmann Wave-Front Sensors

Several techniques have been used with Shack-Hartmann wavefront sensors to determine the local wave-front gradient across each lenslet. In this article we introduce an iterative weighted technique which is specifically targeted for open-loop applications such as aberrometers and metrology. In this article the iterative centroiding technique is compared to existing techniques such as center-of-mass with thresholding, weighted center-of-gravity, matched filter and cross-correlation. Under conditions of low signal-to-noise ratio, the iterative weighted centroiding algorithm is demonstrated to produce a lower variance in the reconstructed phase than existing techniques. The iteratively weighted algorithm was also compared in closed-loop and demonstrated to have the lowest error variance along with the weighted center-of-gravity, however, the iteratively weighted algorithm removes the bulk of the aberration in roughly half the iterations than the weighted center-of-gravity algorithm. This iterative weighted algorithm is also well suited to applications such as guiding on telescopes