3,514 research outputs found
Modelling delay and noise in arbitrarily coupled RC trees.
No full textClosed-form equations for second-order transfer functions of general arbitrarily coupled resistance-capacitance (RC) trees with multiple drivers are reported. The models allow precise delay and noise calculations for systems of coupled interconnects with guaranteed stability and represent the minimum complexity associated with this class of circuits. Their accuracy is extensively compared against other relevant models and is found to be better or comparable to more expensive models. All results are derived from a theoretical approach, and their physical basis is examined. The simplicity, accuracy, and generality of the models make them suitable for use in early signal integrity analyses of complex systems and incremental physical optimization
Reversibility of brain lesions in a case of Neuro-Behçet's disease studied by MR diffusion.
No full textAIDS encefalico: le basi biofisiche della diagnostica per immagini. Ruolo dei parametri biofisici in TC, TRM, SPECT e PET
No full textLa tomografia a RM encefalica nell’infezione e nella malattia da HIV. Criteri orientativi per la diagnostica differenziale
No full textA Compact 10-MHz RC Frequency Reference With a Versatile Temperature Compensation Scheme
No full textThis article presents the design and implementation of a compact CMOS RC frequency reference. It consists of a frequency-locked loop (FLL) that locks the period of a voltage-controlled oscillator (VCO) to the time an RC network takes to charge to a reference voltage. Conventionally, an RC time constant with a near-zero temperature coefficient (TC) is realized by using a trimmed network of resistors with different TCs. In this work, such a network is used to realize a temperature-dependent reference voltage whose TC cancels that of a single-resistor RC time constant. Compared with the conventional approach, which requires resistors with TCs of opposite polarity, the proposed approach can be implemented with resistors with TCs of similar polarity, and so it can be implemented in most CMOS processes. To compensate for RC spread, a trimmed capacitor is used to adjust the nominal frequency. Two prototype chips were made, one based on p- /n-polysilicon resistors and other based on silicided/p-diffusion resistors. Fabricated in a standard 180-nm CMOS technology, the polysilicon-based prototype has an active area of 0.01 mm2 and an absolute inaccuracy of ±2800 ppm from -45 °C to 125 °C with a fixed TC-trim and a one-point frequency trim. After one week of accelerated aging at 150 °C, however, significant drift (5000 ppm) was observed. The diffusion-based prototype exhibits greater inaccuracy (±14 400 ppm) but much less drift (600 ppm).Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
Supervised automatic procedure to identify new lesions in brain MR longitudinal studies of patients with multiple sclerosis.
No full textREGRESSION OF SYMPTOMS AFTER SELECTIVE IRON CHELATION THERAPY IN A CASE OF NEURODEGENERATION WITH BRAIN IRON ACCUMULATION (NBIA).
No full textFibroma of tendon sheath in the distal Forearm with associated median nerve neuropathy: US, CT and MR appearance
No full textMagnetic resonance spectroscopy facilitates assessment of intramyocellular lipid changes: a preliminary short-term study following biliopancreatic diversion.
No full textBACKGROUND: Intramyocellular content of lipid (IMCL) appears to be important in
the pathogenesis of insulin resistance, and the improvement of insulin activity
observed following biliopancreatic diversion (BPD) for obesity has to be related
to reduction of IMCL. This study evaluates the possibility of detecting changes
after BPD in IMCL by means of H1 magnetic resonance spectroscopy.
METHODS: The investigation was carried out in obese patients undergoing BPD prior
to and at 1 month following the operation. Insulin sensitivity was assessed
according to the homeostatic model of assessment (HOMA), and IMCL was determined
by the spectroscopy of the tibialis anterior muscle.
RESULTS: At 1 month following BPD, an improvement in insulin action was observed
in all subjects, and in nearly all cases the IMCL signal decreased.
CONCLUSION: The data from this study indicate that magnetic resonance
spectroscopy can detect IMCL changes following BPD and is fully suitable for
longitudinal studies on muscle metabolic status
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