Structural Test Approach for Embedded Analog Circuits Based on a Built-in Current Sensor

This paper presents a test method based on the analysis of the dynamic power supply current, both quiescent and transient, of the circuit under test. In an off-chip measurement, the global interconnect impedance associated with the chip package and the test equipment and, also, the chip input/output cells will complicate the extraction of the information provided by the current waveform of the circuit under test. Thus, the supply current is measured on-chip by a built-in current sensor integrated in the die itself. To avoid the effective reduction of the voltage supply, the measurement is performed in parallel by replicating the current that flows through selected branches of the analog circuit. With the aim of reducing the test equipment requirements, the built-in current sensor output generates digital level pulses whose width is related to the amplitude and duration of the circuit current transients. In this way the defective circuit is exposed by comparing the digital signature of the circuit under test with the expected one for the fault-free circuit. A fault evaluation has been carried out to check the efficiency of the proposed test method. It uses a fault model that considers catastrophic and parametric faults at transistor level. Two benchmark circuits have been fabricated to experimentally verify the defect detection by the built-in current sensor. One is an operational amplifier; the other is a structure of switched current cells that belongs to an analog-to-digital converter.     

Superparamagnetic Twist‐Type Actuators with Shape‐Independent Magnetic Properties and Surface Functionalization for Advanced Biomedical Applications

Directed nanoparticle self‐organization and two‐photon polymerization are combined to enable three‐dimensional soft‐magnetic microactuators with complex shapes and shape‐independent magnetic properties. Based on the proposed approach, single and double twist‐type swimming microrobots with programmed magnetic anisotropy are demonstrated, and their swimming properties in DI‐water are characterized. The fabricated devices are actuated using weak rotating magnetic fields and are capable of performing wobble‐free corkscrew propulsion. Single twist‐type actuators possess an increase in surface area in excess of 150% over helical actuators with similar feature size without compromising the forward velocity of over one body length per second. A generic and facile combination of glycine grafting and subsequent protein immobilization exploits the actuator's increased surface area, providing for a swimming microrobotic platform with enhanced load capacity desirable for future biomedical applications. Successful surface modification is confirmed by FITC fluorescence.     

The necessity of sample quality assessment in 14C AMS dating: The case of Cova des Pas (Menorca – Spain)

The Cova des Pas cave is a karstic cave in the cliffs of the Barranc (canyon) de Trebalúger. It is a small cave only 6.5 m deep, 4.5 m wide and 1.7 m high. Yet more than 70 burials, in foetal position, from the Early Iron Age were found in this small cave. The conservation of the archaeological remains was very unusual. Not only wood, ropes and other plant material was found, but also remains of body tissue, hair and leather. In spite of the remarkable preservation of the bodies and artefacts, the state of conservation of the bone material was very bad. The bones contained little and heavily deteriorated collagen and the organic plant material was very fragile. The special environmental conditions of the cave are the cause of these unusual preservation conditions. Although the cave is situated in a limestone cliff, the soil of the cave is very acid. Unexpectedly bad sample quality seemed to be the major drawback for AMS radiocarbon dating on hair, wood, ropes and bone collagen, as well as on bio-apatite.     

Sulphur poisoning of transition metal oxides used as catalysts for methane combustion

Different bulk metal oxides (NiO, CuO, Mn₂O₃, Cr₂O₃ and Co₃O₄) were prepared and tested for the combustion of methane–air lean mixtures (5000 ppmV of CH₄) in presence of SO₂ (40 ppmV). Methane combustion experiments were carried out at ambient pressure, 425 and 625 °C and a space time of 93.3 g h mol_CH4⁻¹. Catalysts aged (60 h on stream) both in absence and in presence of SO₂, were characterised by nitrogen physisorption (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature-programmed desorption (TPD-MS) and infrared spectroscopy (DRIFTS). It was observed that Cr₂O₃ is not deactivated at the studied conditions, whereas all the other materials present fast deactivation in presence of SO₂. Aged catalysts characterisation reveals that the outstanding behaviour of the Cr₂O₃ catalyst is caused by the absence of formation of surface sulphates. By contrast, Mn₂O₃ and Co₃O₄ are more active than Cr₂O₃ for methane oxidation in absence of sulphur species, but they are strongly deactivated in presence of SO₂.

Finally, the performance of the Cr₂O₃ catalysts was compared to the corresponding to Pd/Al₂O₃ catalyst and to a highly sulphur-tolerant perovskite (La_0.9Ce_0.1CoO₃) for the oxidation of methane in a real industrial emission from a coke oven, containing different inorganic gases (NH₃, N₂, H₂, H₂O, CO, CO₂, SO₂ and H₂S). Cr₂O₃ catalyst shows to be also the most stable catalyst for the treatment of these emissions.     

Efficiently finding the optimum number of clusters in a dataset with a new hybrid differential evolution algorithm: DELA

Clustering algorithms, a fundamental base for data mining procedures and learning techniques, suffer from the lack of efficient methods for determining the optimal number of clusters to be found in an arbitrary dataset. The few methods existing in the literature always use some sort of evolutionary algorithm having a cluster validation index as its objective function. In this article, a new evolutionary algorithm, based on a hybrid model of global and local heuristic search, is proposed for the same task, and some experimentation is done with different datasets and indexes. Due to its design, independent of any clustering procedure, it is applicable to virtually any clustering method like the widely used \(k\)-means algorithm. Moreover, the use of non-parametric statistical tests over the experimental results, clearly show the proposed algorithm to be more efficient than other evolutionary algorithms currently used for the same task.     

Evaluation of coronary risk in patients with subrenal abdominal aortic aneurysm

Atheroma lesions are often found in multiple localizations. In addition, operative mortality for aneurysms of the non-ruptured sub-renal aorta is mainly related to coronary risk. In an attempt to reduce coronary risk, coronarography was performed in all patients (n = 297) from January 1989. Operation for the aneurysm was performed in 192 patients (reasons for not operating were small size of the aneurysm, other contraindication). There were 5 deaths, all related to coronary artery disease. Coronary bypass was performed in 42 patients either before (n = 38) or at the same time (n = 4) as the operation for the aneurysm of the aorta. There were no operative deaths. These results clearly demonstrate the importance of search and treatment of associated coronary lesions in all patients with an aneurysm of the subrenal abdominal aorta. Coronary lesions should be treated whenever morphology allows.     

Tacrine efficacy in Lewy body dementia

BACKGROUND: Response to tacrine varies among patients with Alzheimer's disease (AD). Lewy body dementia (LBD) could be a high responder subtype of AD. The aim of the study was to compare the effects of tacrine in LBD and AD. METHODS: Seventy-five consecutive outpatients with mild or moderate AD were screened. Tacrine was given at a dose of 40 mg/day during 6 weeks. During the next 6 weeks, the patients were treated with 80 mg/day and afterwards with 120 mg/day. Patients were assessed at baseline and treated with a dose of 120 mg/day tacrine for 2 weeks. RESULTS: Analysis was performed on 39 patients (AD, N = 20; LBD, N = 19). Eight patients were lost to follow-up, eight patients manifested with side-effects, six suffered from an intercurrent somatic disease during the study and 14 patients had poor compliance or were treated with incompatible drugs. Twenty-two patients (11 AD/11 LBD) increased their cognitive performances with tacrine. Among the 22 patients, the improvement differed between the AD and the LBD groups. In AD, conceptualization improved; in LBD, the improvements occurred in verbal initiation and digit span. CONCLUSION: This study emphasizes the importance of using appropriate tests to determine the positive effects of pharmacological treatments.     

Thionitrites as potent donors of nitric oxide: example of S-nitroso- and S,S'-dinitroso-dihydrolipoic acids

Until recently, nitric oxide (NO.) was considered as a toxic radical, but it appears now as an essential messenger implicated in a wide range of biological processes, including immune system, cardiovascular system, and nervous system. An aspect of NO. metabolism in vivo is the formation of a variety of high and low molecular weight nitrosothiols. S-nitrosocysteine and S-nitrosoglutathione are among the biologically derived S-nitrosothiols that are postulated to be carriers of NO.. Although most of the S-nitrosothiols are unstable and spontaneously break down to produce NO. and a disulfide, some of them, including protein thiols, can show significant stability. These molecules are able to convey nitric oxide, that is, to keep, to carry, and then to generate NO. in physiological media, and might display pharmacological effects as potential vasodilators or neuroprotectors. Here, we present the development of new thionitrites R-S-NO having intrinsic antioxidant properties. We report the preparation, the characterization, and the stability studies in aqueous solutions of S-nitroso derivatives of dihydro-alpha-lipoic acid, known for its antioxidant properties.