Cantilever-based electret energy harvesters

Integration of structures and functions allowed reducing electric consumptions of sensors, actuators and electronic devices. Therefore, it is now possible to imagine low-consumption devices able to harvest their energy in their surrounding environment. One way to proceed is to develop converters able to turn mechanical energy, such as vibrations, into electricity: this paper focuses on electrostatic converters using electrets. We develop an accurate analytical model of a simple but efficient cantilever-based electret energy harvester. Therefore, we prove that with vibrations of 0.1g (~1m/s^{2}), it is theoretically possible to harvest up to 30\muW per gram of mobile mass. This power corresponds to the maximum output power of a resonant energy harvester according to the model of William and Yates. Simulations results are validated by experimental measurements but the issues of parasitic capacitances get a large impact. Therefore, we 'only' managed to harvest 10\muW per gram of mobile mass, but according to our factor of merit, this puts us in the best results of the state of the art. http://iopscience.iop.org/0964-1726/20/10/105013Comment: This is an author-created, un-copyedited version of an article accepted for publication in Smart Materials and Structures. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher-authenticated version is available online at doi:10.1088/0964-1726/20/10/105013; http://iopscience.iop.org/0964-1726/20/10/10501

Experimental investigation of a liquid desiccant system for air dehumidification working with ionic liquids

Electrically-driven compression chillers are the commonly used technology for cooling and dehumidifying air. Open sorption systems driven by solar heat are an alternative to conventional air dehumidification technology and may reduce primary energy consumption. For air dehumidification, liquid desiccant systems may exhibit some process engineering and thermodynamic advantages in comparison to solid desiccant systems. The liquid desiccant must exhibit low equilibrium water vapour pressures at the available heat rejection temperature level to achieve low air dew point temperatures and thus a strong air dehumidification with comparably low driving temperatures. Desiccant mass fractions should be as low as possible, but in order to achieve low vapour pressures required desiccant mass fractions may surpass the solubility limit. In the paper at hand, first experimental results of an internally cooled and heated, open liquid desiccant system working with an ionic liquid designed for air dehumidification are presented. It is demonstrated that ionic liquids designed according to the boundary conditions of the respective application may be a promising alternative to commonly used desiccants such as lithium chloride for solar air dehumidification with comparably high heat rejection and low driving temperatures

Participar en la competencia de derecho internacional Phillip C. Jessup

Fil: Ricart, Luciana T. Universidad de Buenos Aires. Facultad de Derecho. Buenos Aires, Argentin

A Large Brightness Enhancement of the QSO 0957+561 A Component

We report an increase of more than 0.2 mag in the optical brightness of the leading image (A) of the gravitational lens Q0957+561, detected during the 09/2000 -- 06/2001 monitoring campaign (2001 observing season). The brightening is similar to or even greater than the largest change ever detected during the 20 years of monitoring of this system. We discuss two different provisional explanations to this event: intrinsic source variability or microlensing (either short timescale microlensing or cessation of the historical microlensing). An exhaustive photometric monitoring of Q0957+561 is needed until summer of 2002 and during 2003 to discriminate between these possibilities.Comment: 13 pages including 3 figures and 1 table. Accepted for publication in ApJ Let

An Umbrella-Shaped Topology for Broadband MEMS Piezoelectric Vibration Energy Harvesting

While cantilever topologies offer high power responsiveness for MEMS vibration energy harvesting (VEH), they are less robust than multiply clamped or membrane topologies. This paper attempts to address this topological optimisation dilemma by attempting to achieve both high power density and robustness. The proposed umbrella-shaped topology constituents of a single central anchor while the membrane area extends outwards and is further enclosed by a ring of proof mass. Implemented on a 0.5 μm AlN on 10 μm doped Si process, a fabricated device (121 mm2 die area) recorded a peak power of 173 μW (1798 Hz and 0.56 g). The normalised power density compares favourably against the state-of-the-art cantilever piezoelectric MEMS VEH, while not sacrificing robustness. Furthermore, this device offers a broadband response, and it has experimentally demonstrated over 3 times higher band-limited noise induced power density than a cantilevered harvester fabricated using the same process

A care bundle approach for prevention of ventilator-associated pneumonia

AbstractImplementation of care bundles for prevention of ventilator-associated pneumonia (VAP) and its impact on patient outcomes requires validation with long-term follow-up. A collaborative multi-centre cohort study was conducted in five Spanish adult intensive-care units. A care bundle approach based on five measures was implemented after a 3-month baseline period, and compliance, VAP rates, intensive-care unit length of stay (ICU LOS) and duration of mechanical ventilation were prospectively recorded for 16 months. There were 149 patients in the baseline period and 885 after the intervention. Compliance with all measures after intervention was <30% (264/885). In spite of this, VAP incidence decreased from 15.5% (23/149) to 11.7% (104/885), after the intervention (p <0.05). This reduction was significantly associated with hand hygiene (OR = 0.35), intra-cuff pressure control (OR = 0.21), oral hygiene (OR = 0.23) and sedation control (OR = 0.51). Use of the care bundle was associated with an incidence risk ratio of VAP of 0.78 (95% CI 0.15–0.99). We documented a reduction of median ICU LOS (from 10 to 6 days) and duration of mechanical ventilation (from 8 to 4 days) for patients with full bundle compliance (intervention period). Efforts on VAP prevention and outcome improvement should focus on achieving higher compliance in hand and oral hygiene, sedation protocols and intracuff pressure control

Time delay of SBS 0909+532

The time delays between the components of a lensed quasar are basic tools to analyze the expansion of the Universe and the structure of the main lens galaxy halo. In this paper, we focus on the variability and time delay of the double system SBS 0909+532A,B as well as the time behaviour of the field stars. We use VR optical observations of SBS 0909+532A,B and the field stars in 2003. The frames were taken at Calar Alto, Maidanak and Wise observatories, and the VR light curves of the field stars and quasar components are derived from aperture and point-spread function fitting methods. We measure the R-band time delay of the system from the chi-square and dispersion techniques and 1000 synthetic light curves based on the observed records. One nearby field star (SBS 0909+532c) is found to be variable, and the other two nearby field stars are non-variable sources. With respect to the quasar components, the R-band records seem more reliable and are more densely populated than the V-band ones. The observed R-band fluctuations permit a pre-conditioned measurement of the time delay. From the chi-square minimization, if we assume that the quasar emission is observed first in B and afterwards in A (in agreement with basic observations of the system and the corresponding predictions), we obtain a delay of - 45 (+ 1)/(- 11) days (95% confidence interval). The dispersion technique leads to a similar delay range. A by-product of the analysis is the determination of a totally corrected flux ratio in the R band (corrected by the time delay and the contamination due to the galaxy light). Our 95% measurement of this ratio (0.575 +/- 0.014 mag) is in excellent agreement with previous results from contaminated fluxes at the same time of observation.Comment: 26 pages, 15 figures, Astronomy and Astrophysics (see also http://www.astro.ulg.ac.be/RPub/Colloques/JENAM/proceedings/proceedings.html - Quasars Section

Data Mining and Machine Learning in Astronomy

We review the current state of data mining and machine learning in astronomy. 'Data Mining' can have a somewhat mixed connotation from the point of view of a researcher in this field. If used correctly, it can be a powerful approach, holding the potential to fully exploit the exponentially increasing amount of available data, promising great scientific advance. However, if misused, it can be little more than the black-box application of complex computing algorithms that may give little physical insight, and provide questionable results. Here, we give an overview of the entire data mining process, from data collection through to the interpretation of results. We cover common machine learning algorithms, such as artificial neural networks and support vector machines, applications from a broad range of astronomy, emphasizing those where data mining techniques directly resulted in improved science, and important current and future directions, including probability density functions, parallel algorithms, petascale computing, and the time domain. We conclude that, so long as one carefully selects an appropriate algorithm, and is guided by the astronomical problem at hand, data mining can be very much the powerful tool, and not the questionable black box.Comment: Published in IJMPD. 61 pages, uses ws-ijmpd.cls. Several extra figures, some minor additions to the tex

Platelet count and Interleukin 6 Gene polymorphism in healthy subjects

BACKGROUND: Interleukin 6 (IL-6) is thought to play important roles in the development of reactive thrombocytosis caused by inflammation by its stimulatory effect on megakaryocytopoiesis. A G/C polymorphism of the IL-6 gene at position -174 has been found to be associated to different transcription rates. Specifically, subjects with the CC genotype showed lower plasma IL-6 levels compared with GC or GG subjects. Given this difference in transcription rates of IL-6 we speculated on different platelet count according to this IL-6 polymorphism. METHODS: The G/C polymorphism of the IL-6 gene at position -174, serum IL-6 concentration and platelet count were prospectively analyzed in 59 (25 women) consecutive healthy subjects. RESULTS: Subjects who were homozygotes for the C allele at position -174 of the IL-6 gene (Sfa NI genotype) showed significantly lower platelet count than carriers of the G allele, despite similar age, sex, body mass index and proportion of smokers (205400 ± 44088 vs 239818 ± 60194, p = 0.047). This was in parallel to differences in peripheral white blood cell count (5807 ± 1671 vs 6867 ± 1192 × 10(9)/ml, p = 0.01). CONCLUSION: This is the first description, to our knowledge, of a genetical influence on basal platelet counts, which appears to be partially dependent on a polymorphism of the IL-6 gene, even in the absence of inflammation