2,906 research outputs found
On the Systematic Synthesis of OTA-Based KHN Filters
According to the nullor-mirror descriptions of OTA, the NAM expansion method for three different types of KHN filters employing OTAs is considered. The type-A filters employing five OTAs have 32 different forms, the type-B filters employing four OTAs have 32 different forms, and the type-C filters employing three OTAs have eight different forms. At last a total of 72 circuits are received. Having used canonic number of components, the circuits are easy to be integrated and both pole frequency and Q-factor can be tuned electronically through tuning bias currents of the OTAs. The MULTISIM simulation results have been included to verify the workability of the derived circuit
Systematic Derivation for Quadrature Oscillators Using CCCCTAs
According to 16 nullor-mirror models of the current-controlled current conveyor transconductance amplifier (CCCCTA) and using nodal admittance matrix (NAM) expansion method, three different classes of the double-mode quadrature oscillators employed CCCCTAs and two grounded capacitors are synthesized. The class I oscillators have 32 different forms, the class II oscillators have 16 different forms, and the class III oscillators have four different forms. In all, 52 quadrature oscillators using CCCCTAs are obtained. Having used canonic number of components, the circuits are easy to be integrated and the condition for oscillation and the frequency of oscillation can be tuned by tuning bias currents of the CCCCTAs. The circuit analysis and simulation results have been included to support the generation method
A systematic approach to circuit design and analysis: classification of Two-VCCS Circuits
This paper discusses a systematic approach to the design and analysis of circuits, using a transconductor or voltage controlled current source (VCCS) as a building block. It is shown that two independent Kirchhoff relations among the VCCS voltages and currents play a crucial role in establishing a unique transfer function in two-port circuits with two VCCSs. A class of two VCCS circuits is defined, which can be subdivided into three main classes and 14 subclasses, based on different imposable sets of two Kirchhoff relations. The classification is useful for circuit synthesis and analysis, as it reveals all the basically different ways to exploit two VCCS's, and allows for a unified analysis of classes of circuits. To exemplify this, all complementary metal-oxide-semiconductor (CMOS) V-I converter kernels, based on two matched MOS transistor (MOST)-VCCSs, are generated and analyzed with respect to distortion. It is shown that dozens of published transconductor circuits can be classified in only four classes, with essentially different distortion behavio
The First Systematic Survey for Lyman Alpha Emitters at z=7.3 with Red-sensitive Subaru/Suprime-Cam
We have performed deep imaging surveys for LyA emitters (LAEs) at redshift
~7.3 in two blank fields, the Subaru Deep Field (SDF) and the Subaru/XMM-Newton
Deep survey Field (SXDF), using the Subaru/Suprime-Cam equipped with new
red-sensitive CCDs and a new narrow-band filter, NB1006 (lambda_c=10052 Ang,
FWHM=214 Ang). We identified four objects as LAE candidates that exhibit
luminosity excess in NB1006. By carrying out deep follow-up spectroscopy for
three of them using Subaru/FOCAS and Keck/DEIMOS, a definitively asymmetric
emission line is detected for one of them, SXDF-NB1006-2. Assuming this line is
LyA, this object is a LAE at z=7.215 which has luminosity of 1.2^{+1.5}_{-0.6}
x 10^43 [erg s-1] and a weighted skewness S_w=4.90+-0.86. Another object,
SDF-NB1006-2, shows variable photometry and is thus probably a quasar (QSO) or
an active galactic nucleus (AGN). It shows an asymmetric emission line at 10076
Ang, which may be due to either LyA at z=7.288 or [OII] at z=1.703. The third
object, SDF-NB1006-1, is likely a galaxy with temporal luminosity enhancement
associated with a supernova explosion, as the brightness of this object varies
between the observed epochs. Its spectrum does not show any emission lines. The
inferred decrease in the number density of LAEs toward higher redshift is
n_LyA(z=7.3)/n_LyA(z=5.7) = 0.05^+0.11_-0.05 from z=5.7 to 7.3 down to
L(LyA)=1.0 x 10^43 [erg s-1]. The present result is consistent with the
interpretation in previous studies that the neutral hydrogen fraction is
rapidly increasing from z=5.7 to 7.3.Comment: 12 pages, 11 figures, Accepted to Ap
Effectiveness of nutrition interventions in low and middle income countries: an evidence summary
This is an independent report commissioned under the DFID Systematic Review Programme for SouthAsia. This material has been funded by South Asia Research Hub, Research and Evidence Division,Department for International Development,Government of UK. The views expressed do not necessarilyreflect the UK Government’s official policies
Synthetic Galaxy Images and Spectra from the Illustris Simulation
We present our methods for generating a catalog of 7,000 synthetic images and
40,000 integrated spectra of redshift z = 0 galaxies from the Illustris
Simulation. The mock data products are produced by using stellar population
synthesis models to assign spectral energy distributions (SED) to each star
particle in the galaxies. The resulting synthetic images and integrated SEDs
therefore properly reflect the spatial distribution, stellar metallicity
distribution, and star formation history of the galaxies. From the synthetic
data products it is possible to produce monochromatic or color-composite
images, perform SED fitting, classify morphology, determine galaxy structural
properties, and evaluate the impacts of galaxy viewing angle. The main
contribution of this paper is to describe the production, format, and
composition of the image catalog that makes up the Illustris Simulation
Obsevatory. As a demonstration of this resource, we derive galactic stellar
mass estimates by applying the SED fitting code FAST to the synthetic galaxy
products, and compare the derived stellar masses against the true stellar
masses from the simulation. We find from this idealized experiment that
systematic biases exist in the photometrically derived stellar mass values that
can be reduced by using a fixed metallicity in conjunction with a minimum
galaxy age restriction.Comment: 21 pages, 17 figures, submitted to MNRAS. Comments welcom
LCDM predictions for galaxy protoclusters I: the relation between galaxies, protoclusters and quasars at z~6
Motivated by recent observational studies of the environment of z~6 QSOs, we
have used the Millennium Run (MR) simulations to construct a very large (~20
deg^2) mock redshift survey of star-forming galaxies at z~6. We use this
simulated survey to study the relation between density enhancements in the
distribution of i-dropouts and Lya-emitters, and their relation to the most
massive halos and protocluster regions at z~6. Our simulation predicts
significant variations in surface density across the sky with some voids and
filaments extending over scales of 1 degree, much larger than probed by current
surveys. Approximately one third of all z~6 halos hosting i-dropouts brighter
than z=26.5 mag (~M* at z=6) become part of z=0 galaxy clusters. i-dropouts
associated with protocluster regions are found in regions where the surface
density is enhanced on scales ranging from a few to several tens of arcminutes
on the sky. We analyze two structures of i-dropouts and Lya-emitters observed
with the Subaru Telescope and show that these structures must be the seeds of
massive clusters-in-formation. In striking contrast, six z~6 QSO fields
observed with HST show no significant enhancements in their i-dropout number
counts. With the present data, we cannot rule out the QSOs being hosted by the
most massive halos. However, neither can we confirm this widely used
assumption. We conclude by giving detailed recommendations for the
interpretation and planning of observations by current and future ground- and
space based instruments that will shed new light on questions related to the
large-scale structure at z~6.Comment: Accepted by MNRAS (19 pages, 20 figures, 2 tables). High resolution
PDF available at http://www.mpa-garching.mpg.de/~overzier/overzierz6.pd
34th Midwest Symposium on Circuits and Systems-Final Program
Organized by the Naval Postgraduate School Monterey California. Cosponsored by the IEEE Circuits and Systems Society.
Symposium Organizing Committee: General Chairman-Sherif Michael, Technical Program-Roberto Cristi, Publications-Michael Soderstrand, Special Sessions- Charles W. Therrien, Publicity: Jeffrey Burl, Finance: Ralph Hippenstiel, and Local Arrangements: Barbara Cristi
Characterization and disruption of the cipC gene in the ochratoxigenic fungus Aspergillus carbonarius
Aspergillus carbonarius is considered the most important ochratoxin A (OTA) producing fungi among those causing OTA contamination in grapes and grape-derived products. CipC is a small protein with unknown function that was previously found to be highly up-regulated in an OTA producer strain of A. carbonarius in comparison to a non OTA producer strain. In this study, cipC was characterized and disrupted via Agrobacterium tumefaciens-mediated transformation in an ochratoxigenic A. carbonarius strain in order to study whether this gene has a role in OTA production. Sequence analysis indicated that the promoter region of cipC contains putative binding sites for transcription factors that regulate the utilization of nutrients, the stress response and detoxification processes, all factors that can influence mycotoxin biosynthesis. Although the {increment}. cipC mutant grew similarly to the wild type strain, the null mutant showed a much higher OTA production. Moreover, when A. carbonarius was grown under the oxidative stress conditions imposed by the presence of hydrogen peroxide, cipC gene expression was up-regulated. These results indicate that cipC is not directly involved in OTA biosynthesis, but sequence analysis of the A. carbonarius cipC gene promoter and the phenotype of the δ cipC disrupted mutant suggests that CipC could be a stress response protein that would be up-regulated concomitantly with OTA production. © 2013 Elsevier Ltd.A. Crespo-Sempere was recipient of a FPI fellowship from the Spanish Government. This research was supported by grants AGL2005-00707 and AGL2008-04828-C03-02 from the Spanish Government.Peer Reviewe
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