228 research outputs found
Electronic tuneability of a structurally rigid surface intermetallic and Kondo lattice: CePt / Pt(111)
We present an extensive study of structure, composition, electronic and
magnetic properties of Ce--Pt surface intermetallic phases on Pt(111) as a
function of their thickness. The sequence of structural phases appearing in low
energy electron diffraction (LEED) may invariably be attributed to a single
underlying intermetallic atomic lattice. Findings from both microscopic and
spectroscopic methods, respectively, prove compatible with CePt formation
when their characteristic probing depth is adequately taken into account. The
intermetallic film thickness serves as an effective tuning parameter which
brings about characteristic variations of the Cerium valence and related
properties. Soft x-ray absorption (XAS) and magnetic circular dichroism (XMCD)
prove well suited to trace the changing Ce valence and to assess relevant
aspects of Kondo physics in the CePt surface intermetallic. We find
characteristic Kondo scales of the order of 10 K and evidence for
considerable magnetic Kondo screening of the local Ce moments.
CePt/Pt(111) and related systems therefore appear to be promising
candidates for further studies of low-dimensional Kondo lattices at surfaces.Comment: 14 pages, 11 figure
Configuration development study of the X-24C hypersonic research airplane
Bottom line results were made of a three-phase study to determine the feasibility of designing, building, and operating, and maintaining an air-launched high performance aircraft capable of cruising at speeds up to Mach 8 for short durations. The results show that Lockalloy heat-sink structure affords the capability for a 'work-horse' vehicle which can serve as an excellent platform for this research. It was further concluded that the performance of a blended wing body configuration surpassed that of a lifting body design for typical X-24C missions. The cost of a two vehicle program, less engines, B-52 modification and contractor support after delivery, can be kept within $70M (in Jan. 1976 dollars)
Nonlinear spin wave excitations at low magnetic bias fields
Nonlinear magnetization dynamics is essential for the operation of numerous spintronic devices ranging from magnetic memory to spin torque microwave generators. Examples are microwave assisted switching of magnetic structures and the generation of spin currents at low bias fields by high amplitude ferromagnetic resonance. Here we use X ray magnetic circular dichroism to determine the number density of excited magnons in magnetically soft Ni80Fe20 thin films. Our data show that the common model of nonlinear ferromagnetic resonance is not adequate for the description of the nonlinear behaviour in the low magnetic field limit. Here we derive a model of parametric spin wave excitation, which correctly predicts nonlinear threshold amplitudes and decay rates at high and at low magnetic bias fields. In fact, a series of critical spin wave modes with fast oscillations of the amplitude and phase is found, generalizing the theory of parametric spin wave excitation to large modulation amplitude
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Three interacting freshwater plumes in the northern California Current System
The northern California Current System is impacted by two primary freshwater
sources: the Strait of Juan de Fuca and the Columbia River. The Columbia is frequently
bidirectional in summer, with branches both north and south of the river mouth
simultaneously. We describe the interaction of these two warm Columbia plumes with
each other and with the colder plume originating from the strait. The interactions occurred
when a period of strong downwelling-favorable winds and high Columbia River
discharge was followed by persistent and strong upwelling-favorable winds. The
northward plume that developed under the downwelling winds extended over 200 km
along the coast to the Strait of Juan de Fuca and into the strait. The plume subsequently
wrapped around Juan de Fuca Strait water in the counterclockwise seasonal eddy just
offshore of the strait. Inspection for similar wind and outflow conditions (>0.15 N m¯²
and 10⁴ m³ s¯¹, respectively) suggest that these events might have occurred in roughly
half the years since 1994. Surface drifters deployed in the Columbia plume near its origin
tracked this plume water northward along the coast, then reversed direction at the onset
of upwelling-favorable winds, tracking plume water southward past the river mouth once
again. ‘‘Recent’’ (~1–2 day old) and ‘‘Aged’’ (>14 day old) plume water folded around
the newly emerging southwest tending Columbia plume, forming a distinctive ‘‘sock’’
shaped plume. This plume was a mixture of ~10% ‘‘New’’ (<1 day old) water
and ~90% Recent and Aged water from prior north tending plumes
Short and long-term results of endoscopic atraumatic coronary artery off-pump bypass grafting in patients with left anterior descending artery stenosis
Background: To perform a retrospective analysis of patients who underwent endoscopic atraumaticcoronary artery off-pump bypass grafting (EACAB) in a single center over a period of 11 years.Methods: Data was acquired from the hospital registry and patient medical records. In order to determine changes in clinical profile, patients were subdivided into three groups regarding year of surgery: 1998–2002 (group 1), 2003–2005 (group 2), 2006–2009 (group 3). In-hospital analysis up to 30 days and long-term observation were conducted.Results: The study cohort consisted of 714 patients (581 male). Procedural success accounted for 99%of all patients. No mortality was observed up to 30 days. Complications in the early period includedpleural effusion (7.6%), cardiac arrhythmias (3.6%), bleeding related revision (2.7%) and woundinfection (1.6%). Mean follow-up was 6 years (2132 ± 1313 days; median: 1918.5). Nineteen (2.7%)patients died, of which 52.6% (10 patients) were due to heart related conditions. Overall frequency ofmajor adverse cerebral and cardiovascular events (MACCE) was 10.8% (77 patients). The Kaplan-Meyer analysis defined survival rate and event-free survival in long-term observation of 96.1% and85.3%, respectively. Ejection fraction (EF) < 50% was the only independent factor of mortality (OR:3.35). Regarding cumulative MACCE, older age (OR: 1.72), lower EF (OR: 3.03), the history of percutaneous coronary intervention (OR: 2.13) and higher New York Heart Association class (OR: 2.63)influenced the incidence rate.Conclusions: The presented short and very long-term results confirm that EACAB is an efficient alternative for patients requiring revascularization of the left anterior descending artery. The eliminationof cardiopulmonary bypass significantly reduces the number of complications
1964 Ruby Yearbook
A digitized copy of the 1964 Ruby, the Ursinus College yearbook.https://digitalcommons.ursinus.edu/ruby/1067/thumbnail.jp
On-site correlation in valence and core states of ferromagnetic nickel
We present a method which allows to include narrow-band correlation effects
into the description of both valence and core states and we apply it to the
prototypical case of nickel. The results of an ab-initio band calculation are
used as input mean-field eigenstates for the calculation of self-energy
corrections and spectral functions according to a three-body scattering
solution of a multi-orbital Hubbard hamiltonian. The calculated quasi-particle
spectra show a remarkable agreement with photoemission data in terms of band
width, exchange splitting, satellite energy position of valence states, spin
polarization of both the main line and the satellite of the 3p core level.Comment: 14 pages, 10 PostScript figures, RevTeX, submitted to PR
1964 Ruby Yearbook
A digitized copy of the 1964 Ruby, the Ursinus College yearbook.https://digitalcommons.ursinus.edu/ruby/1067/thumbnail.jp
The use of modern telemedicine technologies in an innovative optimal cardiac rehabilitation program for patients after myocardial revascularization: Concept and design of RESTORE, a randomized clinical trial
Despite proven efficacy of cardiac rehabilitation (CR) in reducing the all-cause mortality in patients after myocardial revascularization, the penetration of CR, due to patient-related factors and referral rates remains limited. To improve the outcomes, home-based tele-rehabilitation (TR) has been proposed recently. In theory TR enhances the effects of standard CR procedures due to implementation of an intelligent monitoring system designed to ensure optimal training through on-demand transmission of vital signs, aimed at motivating the patients through daily schedule reminders, setting daily goals and creating a platform for mutual feedback. Several meta-analyses assessing various studies comparing these two methods (CR and TR) have proven that they are at least equally effective, with some of the research showing superiority of TR. Although there was a small sample size, lack of long-term follow-up, reporting effects of TR itself, no integration with tools designed for coaching, motivating and promoting a healthy lifestyle constitutes an important limitation. The latter carries a hopeful prognosis for improvement when utilizing a broad-spectrum approach, especially with use of dedicated technological solutions exploiting the fact of a large and yet rapidly increasing penetration of smartphones, mobile PCs and tablets in the population. The above-mentioned findings worked as the basis and rationale for commencing the RESTORE project aimed at developing and delivering state-of-the-art, comprehensive TR for patients after myocardial revascularization and evaluating its molecular aspect in view of how it influences the atherosclerosis progression attenuation. This paper presents the current state and rationale behind the project based on up-to-date TR efficacy data
Two color synchrotron X ray spectroscopy based on transverse resonance island buckets
We report on a novel multi color method of X ray spectroscopy at a Synchrotron radiation source that uses two simultaneously filled electron orbits in an electron storage ring to generate multiple soft or tender X ray beams of different wavelength. To establish the second orbit, we use nonlinear beam dynamics in the so called TRIBs transverse resonance island buckets mode of the BESSY II storage ring, where a second electron orbit winds around the regular one leading to transversely separated source points. X ray beams of multiple colors are generated by imaging the individual source points via different pathways through a monochromator. The particular colors can be varied by changing the traversal electron beam positions through storage ring parameters and or via the monochromator dispersion. As a proof of principle, X ray absorption spectroscopy is performed on thin Fe films in transmission as well as a scanning transmission measurement on a Fe3GeTe2 sample of inhomogeneous thickness normalizing resonant signals with the pre edge intensity. Using the extraordinary pointing fidelity of successive X ray macro pulses arriving at MHz repetition rates, a detection of tiny contrasts in diluted systems, contrast enhancement in X ray microscopy as well as fast dynamics studies come into reac
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