Current-limiting and ultrafast system for the characterization of resistive random access memories.

A new system for the ultrafast characterization of resistive switching phenomenon is developed to acquire the current during the Set and Reset process in a microsecond time scale. A new electronic circuit has been developed as a part of the main setup system, which is capable of (i) applying a hardware current limit ranging from nanoampers up to miliampers and (ii) converting the Set and Reset exponential gate current range into an equivalent linear voltage. The complete system setup allows measuring with a microsecond resolution. Some examples demonstrate that, with the developed setup, an in-depth analysis of resistive switching phenomenon and random telegraph noise can be made.

Estudio observacional multicéntrico español de primeros episodios sugestivos de esclerosis múltiple: cohorte PREM / Spanish multi-centre observational study of the fi rst attacks suggestive of multiple sclerosis: the PREM cohort

Introducción. Estudios recientes han demostrado la necesidad de optimizar el manejo de los pacientes tras un primer brote sugerente de esclerosis múltiple (EM). Nuestro objetivo es comprobar si los resultados de seguimiento de estos estudios son reproducibles en un contexto multicéntrico español. Pacientes y métodos. El estudio PREM (estudio multicéntrico español prospectivo observacional a 24 meses) incluyó a pacientes en los tres primeros meses tras un primer brote sugerente de EM con al menos dos lesiones típicas en una resonancia magnética. Se obtuvo la Expanded Disability Status Scale (EDSS) y se valoró la presencia de brotes basalmente y a los 3, 6, 9, 12, 18 y 24 meses; se realizó una resonancia magnética basalmente y a los 6 y 24 meses, para el cálculo del volumen cerebral y de volúmenes lesionales (T1, T2 y T1 tras la administración de gadolinio). Se valoraron los criterios de McDonald y Poser durante el seguimiento. Un subgrupo de pacientes fue seguido hasta completar cuatro años. Resultados. Se incluyó a 110 pacientes (un 67% mujeres) de edad media de 30,2 años; 22 pacientes abandonaron prematuramente el estudio. Un 19% y un 45% de pacientes cumplían criterios de Poser a los 6 meses y 24 meses, respectivamente; un 63% y un 71% en el caso de los criterios de McDonald. La EDSS descendió signifi cativamente (–0,94; p < 0,001) y se observó desarrollo de atrofi a (–1,2%; p < 0,001) a los 24 meses. Conclusión. Los resultados de seguimiento de pacientes con primeros brotes sugerentes de EM en un contexto multicéntrico español son superponibles a los de los ensayos clínicos internacionales realizados en estos pacientes (AU)

Introduction. Recent studies have shown the need to optimise the management of patients after a fi rst attack suggestive of multiple sclerosis (MS). Our aim is to determine whether the results from follow-ups in these studies are reproducible within a Spanish multi-centre context. Patients and methods. The PREM study (observational prospective Spanish multi-centre study at 24 months) included patients in the fi rst three months following a fi rst event suggestive of MS with at least two typical lesions in a magnetic resonance scan. The Expanded Disability Status Scale (EDSS) was obtained and the presence of attacks was evaluated basally and at 3, 6, 9, 12, 18 and 24 months; a magnetic resonance scan was performed basally and at 6 and 24 months so as to be able to calculate the brain volume and the volumes of the lesions (T1, T2 and T1 after administering gadolinium). McDonald and Poser criteria were evaluated during the follow-up. A subgroup of patients was followed up for a total eriod of four years. Results. Altogether 110 patients (67% females) with a mean age of 30.2 years were included in the study; 22 patients dropped out of the study before it fi nished. Poser criteria were met by 19% and 45% of patients at 6 months and 24 months, respectively; 63% and 71% satisfi ed McDonald criteria. The EDSS decreased signifi cantly (–0.94; p < 0.001) and development of atrophy was observed (–1.2%; p < 0.001) at 24 months. Conclusions. Results of the follow-up of patients with fi rst attacks suggestive of MS within a Spanish multi-centre context are wholly comparable with those from international clinical trials performed in these patients (AU)

Note: Electrical resolution during conductive atomic force microscopy measurements under different environmental conditions and contact forces.

Conductive atomic force microscopy experiments on gate dielectrics in air, nitrogen, and UHV have been compared to evaluate the impact of the environment on topography and electrical measurements. In current images, an increase of the lateral resolution and a reduction of the conductivity were observed in N(2) and, especially, in UHV (where current depends also on the contact force). Both effects were related to the reduction/elimination of the water layer between the tip and the sample in N(2)/UHV. Therefore, since current measurements are very sensitive to environmental conditions, these factors must be taken into consideration when comparisons between several experiments are performed.

Measures in the first year of therapy predict the response to interferon beta in MS.

BACKGROUND AND OBJECTIVE: Several criteria for treatment response to interferon beta (IFNbeta) have been proposed, although there is no consensus among different investigators. Hence, the aim of this study was to investigate magnetic resonance imaging (MRI) and clinical predictors of response during the first 12 months of therapy. METHODS: This is a prospective and longitudinal study of relapsing-remitting multiple sclerosis (RRMS) patients treated with IFNbeta. Patients were classified based on the presence of new lesions on MRI, relapses, confirmed disability increase, or combinations of all these variables after 1 year of therapy. Regression analysis was performed in order to identify variables of response after a follow-up of 3 years. RESULTS: We included 222 RRMS patients. The logistic model demonstrated that only the combination of new active lesions on MRI with the presence of relapses (OR 4.4; 95% CI 1.6-12.5) or disability progression (Odds Ratio (OR) 7.1; 95% Confidence Interval (CI) 1.6-33.9), or both (OR 6.5; 95% CI 1.9-23.4) achieved significant values to identify those patients with a poor outcome. CONCLUSIONS: In RRMS patients treated with IFNbeta, the combination of measures of disease activity and the presence of new active lesions on MRI may have a prognostic value for identifying patients with disease activity in the second and third year of therapy.

Improving the electrical performance of a conductive atomic force microscope with a logarithmic current-to-voltage converter.

A new configuration of conductive atomic force microscope (CAFM) is presented, which is based in a standard CAFM where the typical I-V converter has been replaced by a log I-V amplifier. This substitution extends the current dynamic range from 1-100 pA to 1 pA-1 mA. With the broadening of the current dynamic range, the CAFM can access new applications, such as the reliability evaluation of metal-oxide-semiconductor gate dielectrics. As an example, the setup has been tested by analyzing breakdown spots induced in SiO2 layers.