4,896 research outputs found
CMOS array design automation techniques
A low cost, quick turnaround technique for generating custom metal oxide semiconductor arrays using the standard cell approach was developed, implemented, tested and validated. Basic cell design topology and guidelines are defined based on an extensive analysis that includes circuit, layout, process, array topology and required performance considerations particularly high circuit speed
Control of Material Damping in High-Q Membrane Microresonators
We study the mechanical quality factors of bilayer aluminum/silicon-nitride
membranes. By coating ultrahigh-Q Si3N4 membranes with a more lossy metal, we
can precisely measure the effect of material loss on Q's of tensioned resonator
modes over a large range of frequencies. We develop a theoretical model that
interprets our results and predicts the damping can be reduced significantly by
patterning the metal film. Using such patterning, we fabricate Al-Si3N4
membranes with ultrahigh Q at room temperature. Our work elucidates the role of
material loss in the Q of membrane resonators and informs the design of hybrid
mechanical oscillators for optical-electrical-mechanical quantum interfaces
Multisystem Langerhans' cell histiocytosis (Hand-SchĂŒller-Christian disease) in an adult: a case report and review of the literature
Langerhans' cell histiocytosis (LCH) is a rare and enigmatic clonal disorder that affects mainly children. It is characterized by single or multiple granulomatous mass lesions composed of cells with the Langerhans' cell phenotype. Clinical presentation and behavior are heterogeneous and can range from a solitary lytic bone lesion (i.e., eosinophilic granuloma) with a favorable course to a fatal disseminated leukaemia-like form, with a wide spectrum of intermediate clinical presentations between these two extremes. Although LCH typically involves the bone, lesions can be found in almost all organs. We are reporting the case of a multisystem LCH in a 47-year-old patient who presented with a panhypopituitarism and diabetes insipidus, and who, 5years later, developed mandibular, mastoid and femoral lesions. The final diagnosis of LCH was made on mandibular biops
Clear sky fraction above Indonesia: an analysis for astronomical site selection
We report a study of cloud cover over Indonesia based on meteorological
satellite data, spanning over the past 15 years (from 1996 to 2010) in order to
be able to select a new astronomical site capable to host a multi-wavelength
astronomical observatory. High spatial resolution of meteorological satellite
data acquired from {\it Geostationary Meteorological Satellite 5} ({\it GMS
5}), {\it Geostationary Operational Environmental Satellite 9} ({\it GOES 9}),
and {\it Multi-functional Transport Satellite-1R} ({\it MTSAT-1R}) are used to
derive yearly average clear fractions over the regions of Indonesia. This
parameter is determined from temperature measurement of the IR3 channel (water
vapor, 6.7 m) for high altitude clouds (cirrus) and from the IR1 channel
(10.7 m) for lower altitude clouds. Accordingly, an algorithm is developed
to detect the corresponding clouds. The results of this study are then adopted
to select the best possible sites in Indonesia to be analysed further by
performing in situ measurements planned for the coming years. The results
suggest that regions of East Nusa Tenggara, located in south-eastern part of
Indonesia, are the most promising candidates for such an astronomical site.
Yearly clear sky fraction of this regions may reach better than 70 per cent
with an uncertainty of 10 per cent.Comment: 15 pages, 13 figures, and 4 table
The connective tissue cells of human dental pulp: An histologic and immunohistochemical study
Twenty human healthy teeth were extracted for orthondontic purposes and processed for histological, and immunohistochemical examination. Odontoblasts were pseudostratified in depth of 1-8 cells in pulpward direction showing the zone of Weil and the cell-rich zone in coronal third pulp. In the central part of pulp tissue, fibroblasts were arranged as a network. These cells strongly immunoreacted with an antibody (monoclonal and polyclonal) directed against the intermediate filament vimentin. The product reaction was specifically located in the cytoplasm. Near vessels occasional lymphocytes and mast cells were also present. Collagen fibers formed a plexus below the cell-rich zone in middle and coronal pulp.Vingt dents humaines saines ont Ă©tĂ© avulsĂ©es pour des raisons orthodontiques et traitĂ©es pour ĂȘtre examinĂ©es du point de vue histologique et par immunohistochimie. Les odontoblastes Ă©taient pseudostratifiĂ©s (1-8 cellules) et dans le tiers coronaire de la pulpe soit la zone de Weil une zone riche en cellules est prĂ©sente. Dans la partie centrale de la pulpe, les fibroblastes forment un rĂ©seau. Ces cellules sont fortement immuno-marquĂ©es par un anticorps (monoclonal ou polyclonal) dirigĂ© contre la vimentine. Le marquage est spĂ©cifiquement localisĂ© dans le cytoplasme. A proximitĂ© des vaisseaux, des mastocytes ainsi que des lymphocytes sont prĂ©sents. Les fibres de collagĂšne forment un plexus au-dessous de la zone cellulaire riche dans la partie coronaire et centrale de la pulpe
HST/ACS weak lensing analysis of the galaxy cluster RDCS 1252.9-2927 at z=1.24
We present a weak lensing analysis of one of the most distant massive galaxy
cluster known, RDCS 1252.9-2927 at z=1.24, using deep images from the Advanced
Camera for Survey (ACS) on board the Hubble Space Telescope (HST). By taking
advantage of the depth and of the angular resolution of the ACS images, we
detect for the first time at z>1 a clear weak lensing signal in both the i
(F775W) and z (F850LP) filters. We measure a 5-\sigma signal in the i band and
a 3-\sigma signal in the shallower z band image. The two radial mass profiles
are found to be in very good agreement with each other, and provide a
measurement of the total mass of the cluster inside a 1Mpc radius of M(<1Mpc) =
(8.0 +/- 1.3) x 10^14 M_\odot in the current cosmological concordance model h
=0.70, \Omega_m=0.3, \Omega_\Lambda=0.7, assuming a redshift distribution of
background galaxies as inferred from the Hubble Deep Fields surveys. A weak
lensing signal is detected out to the boundary of our field (3' radius,
corresponding to 1.5Mpc at the cluster redshift). We detect a small offset
between the centroid of the weak lensing mass map and the brightest cluster
galaxy, and we discuss the possible origin of this discrepancy. The cumulative
weak lensing radial mass profile is found to be in good agreement with the
X-ray mass estimate based on Chandr and XMM-Newton observations, at least out
to R_500=0.5Mpc.Comment: 38 pages, ApJ in press. Full resolution images available at
http://www.eso.org/~prosati/RDCS1252/Lombardi_etal_accepted.pd
Beyond the pale?: the implications of the RSLG Report for non-CURL modern university libraries: Perspectives on the support libraries group: Final report
We have shown that the cluster-mass reconstruction method
which combines strong and weak gravitational lensing data, developed
in the first paper in the series, successfully reconstructs the
mass distribution of a simulated cluster. In this paper we apply the method to the
ground-based high-quality multi-colour data of RX J1347.5-114
Simulations of Damped Lyman-Alpha and Lyman Limit Absorbers in Different Cosmologies: Implications for Structure Formation at High Redshift
We use hydrodynamic cosmological simulations to study damped Lyman-alpha
(DLA) and Lyman limit (LL) absorption at redshifts z=2-4 in five variants of
the cold dark matter scenario. Our standard simulations resolve the formation
of dense concentrations of neutral gas in halos with circular velocity v_c
roughly 140 km/s for Omega_m=1 and 90 km/s for Omega_m=0.4, at z=2; an
additional LCDM simulation resolves halos down to v_c approximately 50 km/s at
z=3. We find a clear relation between HI column density and projected distance
to the center of the nearest galaxy, with DLA absorption usually confined to
galactocentric radii less than 10-15 kpc and LL absorption arising out to
projected separations of 30 kpc or more. Detailed examination provides evidence
of non-equilibrium effects on absorption cross-section. If we consider only
absorption in the halos resolved by our standard simulations, then all five
models fall short of reproducing the observed abundance of DLA and LL systems
at these redshifts. If we extrapolate to lower halo masses, we find all four
models are consistent with the observed abundance of DLA systems if the the
extrapolated behavior extends to circular velocities roughly 50-80 km/s, and
they may produce too much absorption if the relation continues to 40 km/s. Our
results suggest that LL absorption is closely akin to DLA absorption, arising
in less massive halos or at larger galactocentric radii but not caused by
processes acting on a radically different mass scale.Comment: 33 pages with 10 embedded EPS figures. Substantially revised and
updated from original version. Includes new high-resolution simulations.
Accepted for publication in the Ap
Poly Spotlight Control
When this project began, The Cambria Center for the Arts Theater used a manually-operated spotlight. The sound created by the fans, along with the sheer size of the spotlight, required that it be housed in an attic room above the theater and shined through a closed window. This trapped a lot of heat in the room and involved some risk with climbing into and out of the attic room. This project sought to remedy those issues by mounting a pair of newer LED spotlights inside the theater. Doing this required a method for remotely controlling and actuating the angular position of each spotlight in two axes. Over the course of one year, the Dynalux team researched, designed, and built a solution to CCATâs problem. The process by which they completed those steps is written in detail within this report. The first third of the year was spent in research and development. The team compared commercial and industry options to determine the best practices and designs. Many of the available options were too complicated or expensive and this reiterated that a cheaper and easier system was needed. At this point, Team Dynalux came up with a preliminary design that met all the design constraints. The next third of the year was dedicated to detailed analysis and proving that the design would work as intended. This included looking at all aspects of the system from motor torque requirements to strength and material properties. At this stage, the design was presented to the sponsor and advisors to begin manufacturing. The remainder of the project consisted of manufacturing, assembling, and testing. Some aspects had to be changed on-the-fly but the majority of the design remained the same throughout. Upon concluding machining and welding, the metal parts were finished and assembled with off-the-shelf components. When the mounts were complete, the electronics were added and tested in the overall system. Testing and manufacturing were time intensive but kept safety and reliability as the highest priority. The contents of this report are intended to document the process by which the project was completed but also provide reference to the parts and techniques used to build the system. Also included are comprehensive drawings and instructions to make sure the system is running smoothly, and if needed, provide maintenance
The Population of Damped Lyman-alpha and Lyman Limit Systems in the Cold Dark Matter Model
Lyman limit and damped Lyman-alpha absorption systems probe the distribution
of collapsed, cold gas at high redshift. Numerical simulations that incorporate
gravity and gas dynamics can predict the abundance of such absorbers in
cosmological models. We develop a semi-analytical method to correct the
numerical predictions for the contribution of unresolved low mass halos, and we
apply this method to the Katz et al. (1996) simulation of the standard cold
dark matter model (, , , ). Using
this simulation and higher resolution simulations of individual low mass
systems, we determine the relation between a halo's circular velocity and
its cross section for producing Lyman limit or damped absorption. We combine
this relation with the Press-Schechter formula for the abundance of halos to
compute the number of absorbers per unit redshift. The resolution correction
increases the predicted abundances by about a factor of two at z=2, 3, and 4,
bringing the predicted number of damped absorbers into quite good agreement
with observations. Roughly half of the systems reside in halos with circular
velocities v_c>100\kms and half in halos with 35\kms. Halos
with v_c>150\kms typically harbor two or more systems capable of producing
damped absorption. Even with the resolution correction, the predicted abundance
of Lyman limit systems is a factor of three below observational estimates,
signifying either a failure of standard CDM or a failure of these simulations
to resolve the systems responsible for most Lyman limit absorption. By
comparing simulations with and without star formation, we find that depletion
of the gas supply by star formation affects absorption line statistics at
only for column densities exceeding .Comment: AASlatex, 17 pages w/ 3 embedded ps figures. Submitted to Ap
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