35,743 research outputs found
True high-order VCO-based ADC
A novel approach to use a voltage-controlled oscillator (VCO) as the first integrator of a high-order continuous-time delta-sigma modulator (CT-DSM) is presented. In the proposed architecture, the VCO is combined with a digital up-down counter to implement the first integrator of the CT-DSM. Thus, the first integrator is digital-friendly and hence can maximally benefit from technological scaling
On the Jacobi-Metric Stability Criterion
We investigate the exact relation existing between the stability equation for
the solutions of a mechanical system and the geodesic deviation equation of the
associated geodesic problem in the Jacobi metric constructed via the
Maupertuis-Jacobi Principle. We conclude that the dynamical and geometrical
approaches to the stability/instability problem are not equivalent.Comment: 14 pages, no figure
Design-thinking, making, and innovating: Fresh tools for the physician\u27s toolbox
Medical school education should foster creativity by enabling students to become \u27makers\u27 who prototype and design. Healthcare professionals and students experience pain points on a daily basis, but are not given the tools, training, or opportunity to help solve them in new, potentially better ways. The student physician of the future will learn these skills through collaborative workshops and having dedicated \u27innovation time.\u27 This pre-clinical curriculum would incorporate skills centered on (1) Digital Technology and Small Electronics (DTSE), (2) Textiles and Medical Materials (TMM), and (3) Rapid Prototyping Technologies (RPT). Complemented by an on-campus makerspace, students will be able to prototype and iterate on their ideas in a fun and accessible space. Designing and making among and between patients and healthcare professionals would change the current dynamic of medical education, empowering students to solve problems in healthcare even at an early stage in their career. By doing so, they will gain empathy, problem-solving abilities, and communication skills that will extend into clinical practice. Our proposed curriculum will equip medical students with the skills, passion, and curiosity to impact the future of healthcare
Anomalous Parallel Field Negative Magnetoresistance in Ultrathin Films Near the Superconductor-Insulator Transition
A parallel field negative magnetoresistance has been found in
quench-condensed ultrathin films of amorphous bismuth in the immediate vicinity
of the thickness-tuned superconductor-insulator transition. The effect appears
to be a signature of quantum fluctuations of the order parameter associated
with the quantum critical point.Comment: Revised content includes revised argument and new figures 3 and 4.
Totals: 4 pages, 4 figure
Finite size effects in adsorption of helium mixtures by alkali substrates
We investigate the behavior of mixed 3He-4He droplets on alkali surfaces at
zero temperature, within the frame of Finite Range Density Functional theory.
The properties of one single 3He atom on 4He_N4 droplets on different alkali
surfaces are addressed, and the energetics and structure of 4He_N4+3He_N3
systems on Cs surfaces, for nanoscopic 4He drops, are analyzed through the
solutions of the mean field equations for varying number N3 of 3He atoms. We
discuss the size effects on the single particle spectrum of 3He atoms and on
the shapes of both helium distributions.Comment: 12 pages, and 12 figures (PNG format
Bottom-loading dilution refrigerator with ultra-high vacuum deposition capability
A Kelvinox 400 dilution refrigerator with the ability to load samples onto
the mixing chamber from the bottom of the cryostat has been combined with an
ultrahigh-vacuum (UHV) deposition chamber equipped with molecular beam sources.
The liquid helium cooled sample transfer mechanism is used in a manner that
allows films to be grown on substrates which are kept at temperatures of order
8K with chamber pressures in the 10^-9 to 10^-10 Torr range. This system
facilitates the growth of quench-condensed ultrathin films which must always be
kept below ~ 12K in a UHV environment during and after growth. Measurements can
be made on the films down to millikelvin temperatures and in magnetic fields up
to 15 T.Comment: 10 pages text, 1figur
Evolved stars in the Local Group galaxies. I. AGB evolution and dust production in IC 1613
We used models of thermally-pulsing asymptotic giant branch (AGB) stars, that
also describe the dust-formation process in the wind, to interpret the
combination of near- and mid-infrared photometric data of the dwarf galaxy IC
1613. This is the first time that this approach is extended to an environment
different from the Milky Way and the Magellanic Clouds (MCs). Our analysis,
based on synthetic population techniques, shows a nice agreement between the
observations and the expected distribution of stars in the colour-magnitude
diagrams obtained with JHK and Spitzer bands. This allows a characterization of
the individual stars in the AGB sample in terms of mass, chemical composition,
and formation epoch of the progenitors. We identify the stars exhibiting the
largest degree of obscuration as carbon stars evolving through the final AGB
phases, descending from 1-1.25Msun objects of metallicity Z=0.001 and from
1.5-2.5Msun stars with Z=0.002. Oxygen-rich stars constitute the majority of
the sample (65%), mainly low mass stars (<2Msun) that produce a negligible
amount of dust (<10^{-7}Msun/yr). We predict the overall dust-production rate
from IC 1613, mostly determined by carbon stars, to be 6x10^{-7}Msun/yr with an
uncertainty of 30%. The capability of the current generation of models to
interpret the AGB population in an environment different from the MCs opens the
possibility to extend this kind of analysis to other Local Group galaxies.Comment: 14 pages, 6 figures, accepted for publication on MNRA
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