Manuel Jimenez

Bio: Manuel Jimenez is an academic researcher from University of Puerto Rico at Mayagüez. The author has contributed to research in topics: Fast Fourier transform & Field-programmable gate array. The author has an hindex of 7, co-authored 61 publications receiving 959 citations. Previous affiliations of Manuel Jimenez include Michigan State University.

Behavioral Modeling Methods for Switched-Capacitor $\Sigma \Delta$ Modulators

Abstract: Sigma-delta Modulators (SigmaDeltaMs) are cornerstone elements in oversampled analog-to-digital converters and digital-to-analog converters (DAC). Although transistor-level simulation is the most accurate approach known for these components, this method becomes impractical for complex systems due to its long computational time requirements. Behavioral modeling has become a viable solution to this problem. In this paper, we study styles and issues in the accurate modeling of low-power, high-speed SigmaDeltaMs and introduce two new behavioral models for switched-capacitor (SC) integrators. The first model is based on the SC integrator transient response, including the effects of the amplifier transconductance, output conductance, and the dynamic capacitive loading effect on the settling time. The second model is based on a symbolic node admittance matrix representation of the system. Nonidealities such as jitter, thermal noise, and DAC mismatch are also addressed and included in a dual-band, GSM/WCDMA, second-order, multibit SigmaDeltaM model with individual level averaging. VHDL-AMS and MATLAB Simulink were used as modeling languages. Both models are validated against experimental data, showing competitive results in the signal-to-noise-plus-distortion ratio. A comparative analysis between the proposed and a traditional model is presented, with emphasis on the degrading effects due to the integrator dynamics. Moreover, a general simulation speed analysis of the proposed models is addressed.

Introduction to Embedded Systems: Using Microcontrollers and the MSP430

Abstract: Introduction.- Number Systems and Data Formats.- Microcomputer Organization.- Assembly Language Programming.- Embedded Programming Using C.- Fundamentals of Interfacing.- Embedded Peripherals.- External World Interfaces.- Principles of Serial Communication.- The Analog Signal Chain.-

Undergraduate research and co-op education: a winning combination

Abstract: The Electrical and Computer Engineering (ECE) Department of the University of Puerto Rico at Mayaguez (UPRM) in collaboration with renowned engineering companies has developed and implemented an educational model joining traditional co-op education and undergraduate research experience. The model has evolved into a well-rounded learning program with important benefits for all parties involved: students, academia, and employers. This paper describes the program, presents statistics quantifying its impact, and identifies key elements for the success of the approach.

Hepatitis aguda por ticlopidina. Presentación de 12 casos y revisión de la literatura

Abstract: OBJECTIVE To analyze the characteristics of hepatotoxicity due to ticlopidine. PATIENTS AND METHODS We describe all the case of hepatotoxicity attributed to ticlopidine and reported to the Register of drug associated hepatopathies. We also obtained data from MEDLINE and the Spanish Medical Index regarding cases reported during the period 1982 2001. RESULTS We reported twelve cases of hepatopathy related to the use of ticlopidine. These made up 5% of all the cases notified to the Register. Eighty three percent of the patients were male, and of an average age of 68 years. Sixty six percent required hospital admission. The latent period varied between 2 and 13 weeks. The liver lesion was of cholestatic type in 75% of the cases, hepatocellular in 16.6% and mixed in 8.3%. Twenty five percent of the patients had received sub therapeutic doses. CONCLUSIONS Ticlopidine is often related to hepatotoxicity. This seems to be due to an idiosyncratic mechanism and is mainly cholestatic. The use of lower dosage than that recommended means that the desired therapeutic effect is not attained but does not protect against the development of hepatotoxicity. Doctors who use this drug should be aware of this so as to establish the true risk benefit relation.

Drug-Related Hepatotoxicity

Abstract: Given its rarity, drug-related hepatotoxicity may not be seen during the initial clinical trials of a new medication. After approval, when many more patients are exposed, toxic effects that are very infrequent may emerge. This review explains the difficulties in identifying the cause of hepatotoxic effects in such situations and provides clinical guidance with regard to the detection, evaluation, and possible prevention of drug-related hepatotoxicity.

Idiosyncratic drug hepatotoxicity

Abstract: The occurrence of idiosyncratic drug hepatotoxicity is a major problem in all phases of clinical drug development and the most frequent cause of post-marketing warnings and withdrawals This review examines the clinical signatures of this problem, signals predictive of its occurrence (particularly of more frequent, reversible, low-grade injury) and the role of monitoring in prevention by examining several recent examples (for example, troglitazone) In addition, the failure of preclinical toxicology to predict idiosyncratic reactions, and what can be done to improve this problem, is discussed Finally, our current understanding of the pathophysiology of experimental drug hepatotoxicity is examined, focusing on acetaminophen, particularly with respect to the role of the innate immune system and control of cell-death pathways, which might provide targets for exploration and identification of risk factors and mechanisms in humans