Analyses of parasitic capacitance effects and flicker noise of the DAC capacitor array for high resolution SAR ADCs

Copyright © 2018 Inderscience Enterprises Ltd. This paper analyses the effects of parasitic capacitances of unit capacitors on the accuracy and the noise performance of the DAC capacitor array in a SAR ADC, showing that thermal noise of the array decreases while gain error is introduced. The gain error is almost independent of the number of bits, but the dynamic range of the high resolution ADC is severely reduced due to the gain error. The post-layout parasitic capacitance analysis of a 10-bit poly-poly array shows a large difference between the top-plate and bottom-plate parasitic capacitances so that the gain error can be decreased by 152 times when top-plates are connected together as the output node of the array. The switching transistors’ flicker noise calculation for a 10-bit and an 18-bit SAR ADC shows that flicker noise can be safely ignored for 10-bit 1MSPS SAR, but should be considered for the higher resolution SAR ADCs

Lensed Quasar Hosts

Gravitational lensing assists in the detection of quasar hosts by amplifying and distorting the host light away from the unresolved quasar core images. We present the results of HST observations of 30 quasar hosts at redshifts 1 < z < 4.5. The hosts are small in size (r_e <~ 6 kpc), and span a range of morphologies consistent with early-types (though smaller in mass) to disky/late-type. The ratio of the black hole mass (MBH, from the virial technique) to the bulge mass (M_bulge, from the stellar luminosity) at 1<z<1.7 is broadly consistent with the local value; while MBH/M_bulge at z>1.7 is a factor of 3--6 higher than the local value. But, depending on the stellar content the ratio may decline at z>4 (if E/S0-like), flatten off to 6--10 times the local value (if Sbc-like), or continue to rise (if Im-like). We infer that galaxy bulge masses must have grown by a factor of 3--6 over the redshift range 3>z>1, and then changed little since z~1. This suggests that the peak epoch of galaxy formation for massive galaxies is above z~1. We also estimate the duty cycle of luminous AGNs at z>1 to be ~1%, or 10^7 yrs, with sizable scatter.Comment: 8 pages, 6 figures, review article with C. Impey at the conference on "QSO Host Galaxies: Evolution and Environment", Aug. 29-Sep. 2, 2005, Lorentz Center, Leiden, The Netherland

An Assessment of the Imaging Performance of Hand-Held Ultrasound Scanners Using the Edinburgh Pipe Phantom

Objective: Although hand-held ultrasound devices (HHUSDs) are currently used for a diverse range of diagnostic and interventional applications the imaging performance of such scanners is rarely considered. The aim of this study was to assess the imaging performance of a wide-range of HHUSDs and compare their imaging performance to cart-based systems utilized for the same clinical applications. Methods: The grayscale imaging performances of 19 HHUSDs from eight different manufacturers, manufactured between 2016 and 2021, were measured using a figure-of-merit known as the resolution integral. The imaging performance of the HHUSDs were compared to 142 cart-based ultrasound scanners. Results: The HHUSD with the overall highest resolution integral (66) was a Butterfly (Burlington, MA, USA) wired phased array for small parts applications, followed by a Philips (Bothell, WA, USA) Lumify wired curvilinear transducer (57) for abdominal applications, a Butterfly wired phased array (56) for abdominal applications, a GE (Freiburg, Baden-Wurttemberg, Germany) VScan Air wireless linear array (56) for small parts applications, and a Healcerion (Seoul, Korea) Sonon 300L wireless linear array (56) for small parts applications. A GE VScan Extend wired phased array had the highest resolution integral (44) for cardiac applications. Conclusions: The Butterfly phased array had the highest resolution integral of all the 19 HHUSDs, although this value is still less than the majority of cart-based cardiac and abdominal ultrasound scanners manufactured from 2010 to 2017. Clinical users of HHUSDs should be mindful of the limitations in imaging performance of hand-held ultrasound devices.</p

SAGITTAL HIP - KNEE COORDINATION DURING A 45 DEGREE CUTTING TASK

Concurrent extension at the hip and flexion at the knee has been suggested as a high risk coordination pattern for the anterior cruciate ligament (ACL). Nine elite female athletes performed ten 45" cutting tasks before and alter a multi-directional fatiguing protocol. Force and kinematic data were captured. Vector coding was used to calculate sagittal hip - knee coordination for the first 40 ms of foot contact of the dominant limb and percentage time spent in each coordination pattern was extracted. Hip extension - knee flexion was the dominant coordination pattern pre- and post-fatigue ( P less than 0.05)t the time spent in this coordination pattern did not change as a result of fatigue. The hypothesised high risk hip extension - knee flexion was the dominant coordination pattern during the 45' cutting task

INTERPRETATION OF VECTOR CODING VARIABILITY MEASURES: WITHINDAY REPEATABILITY AND BETWEEN-SUBJECT VARIATION IN TREADMILL RUNNING

This study investigated the within-day repeatability and between-subject variation of vector coding variability during treadmill running. The lower-limb kinematics of eight male triathletes running at 12 km/h were captured twice on the same day. Mean coupling angle variability across the stride cycle was computed for 20 couplings using the modified vector coding technique. Between-subject variation was calculated from the first data collection and data from both sessions were used to calculate systematic and typical error. Between-subject variation ranged from 1.4° to 3.7°. Systematic errors between sessions were observed for two couplings and typical errors were between 0.6° and 1.9°. The between-subject variation and within-day repeatability of the measures reported will aid the interpretation of vector coding variability in cross-sectional and intervention studies

MAGED2: A novel p53-dissociator

The tumor suppressor protein p53 is a transcription factor that is frequently mutated in human cancers. In response to DNA damage, unmutated or wild-type (wt) p53 protein is stabilized and activated by post-transcriptional modifications that enable it to induce either apoptosis or cell cycle arrest. Using a yeast p53-dissociator assay, we identified MAGED2 as a potential negative regulator of wt p53 activity. Subsequently, using co-immunoprecipitation and reporter gene assays in human cultured cells that are often adopted for functional analysis of p53 we demonstrated that MAGED2 interacted physically with p53 and modified its activity. Finally, we were able to illustrate expression of both p53 and MAGED2 within the same subcellular compartment, i.e. either nucleus or cytoplasm, in 2,682 human cancer tissue specimens using a common cancer tissue microarray and antibodies against MAGED2 and p53. The present results implicate MAGED2, a novel protein, as a p53-dissociator

The Far-infrared Continuum of Quasars

ISO provides a key new far-infrared window through which to observe the multi-wavelength spectral energy distributions (SEDs) of quasars and active galactic nuclei (AGN). It allows us, for the first time, to observe a substantial fraction of the quasar population in the far-IR, and to obtain simultaneous, multi-wavelength observations from 5--200 microns. With these data we can study the behavior of the IR continuum in comparison with expectations from competing thermal and non-thermal models. A key to determining which mechanism dominates, is the measurement of the peak wavelength of the emission and the shape of the far-IR--mm turnover. Turnovers which are steeper than frequency^2.5 indicate thermal dust emission in the far-IR. Preliminary results from our ISO data show broad, fairly smooth, IR continuum emission with far-IR turnovers generally too steep to be explained by non-thermal synchrotron emission. Assuming thermal emission throughout leads to a wide inferred temperature range of 50-1000 K. The hotter material, often called the AGN component, probably originates in dust close to and heated by the central source, e.g. the ubiquitous molecular torus. The cooler emission is too strong to be due purely to cool, host galaxy dust, and so indicates either the presence of a starburst in addition to the AGN or AGN-heated dust covering a wider range of temperatures than present in the standard, optically thick torus models.Comment: 4 pages, to be published in the proceedings of "The Universe as Seen by ISO," ed. M. Kessler. This and related papers can be found at http://hea-www.harvard.edu/~ehooper/ISOkp/ISOkp.htm

Sagittal hip-knee coordination during a 45 degree cutting task

Background Hashemi et al. (2011) put forward a new theory of ACL injury mechanism, named the ‘hip extension knee flexion paradox’ that attempted to integrate itself with the most convincing findings in ACL research. This theory of mechanism stated that non-contact ACL injury would occur when the following four criteria are simultaneously met: 1) the tibial plateau has a posterior slope 2) the knee is near full extension upon application of a dynamic ground reaction force 3) activation of musculature about the knee is delayed and 4) hip extension and knee flexion occur concurrently. In their paper, Hashemi et al. (2011) also suggest that fatigue may play an important role in increasing the risk of non-contact ACL injury by delaying activation of musculature about the knee joint. Hip-knee coordination and the effect of fatigue on it, have however not previously been investigated. Purpose The purpose of this study was to quantify hip – knee coordination in the sagittal plane during a 45° cutting movement. Methods Nine female team sports players with experience at international or national level and no history of ACL injury were recruited. Written consent was obtained at the time of testing. Cutting was assessed under pre and post fatigue conditions, whilst motion capture data were collected for the lower limbs using QTM (Qualysis AB, Göteburg, Sweden). In each condition, ten successful 45° cuts were captured for the dominant leg. The fatiguing protocol comprised drop maximal vertical jumps and a multi-directional short sprint exercise. Hip and knee sagittal joint angles were extracted between the time of foot contact to 40 ms, the window in which ACL injury is believed to occur. A coordination pattern of 1) hip flexion – knee flexion, 2) hip extension – knee flexion, 3) hip extension – knee extension, 4) hip extension knee flexion was determined for each time point. The average time that each participant spent in each coordination pattern was calculated and the median coordination pattern was determined for each participant at each time point. Wilcoxon tests were executed in SPSS (IBM SPSS Version 22, Armonk, NY) to determine the effect of fatigue on the percentage time spent in hip extension – knee flexion and hip extension – knee extension. Results The average modal coordination pattern of the group, both pre- and post-fatigue, was to extend the hip and knee for the first 10 ms after foot contact. By 25 ms, all participants had changed coordination pattern to flex at the knee whilst continuing to extend at the hip. Both pre- and post-fatigue, a greater percentage of time (p&lt;0.05) was spent in hip extension – knee flexion than in hip extension – knee extension. No change was seen in the percentage time spent in hip extension – knee flexion after fatigue. Practical Applications Most players adopted a hip extension – knee extension pattern at foot contact before switching to hip extension – knee flexion. The initial observation of hip extension – knee extension was interesting as it represents stiffness at both the hip and knee joint, which has been suggested as high risk for non-contact ACL injury (Pollard et al., 2010). The latter coordination pattern has also been hypothesised as high risk for non-contact ACL injury and was dominant both pre- and post-fatigue. The absence of change in coordination patterns after fatigue suggests this risk factor was not accentuated as a result of a short duration fatiguing protocol in an elite, healthy population