731 research outputs found
A tunable line filter polychromator for gas temperature measurements using laser Raman scattering
A proprietary laser line filter spectrograph (LLFS) was modified to test for improved remote measurement of atmospheric temperature by Raman spectroscopy of the rotational bands of N2 and O2. Both grating scan measurements with fixed PMT and polychromator image plane PMT scans with fixed grating setting were made using HeNe and Ar(+) lasers. The LLFS was found to have a laser line rejection ratio at 6A from the laser line and provides resolved rotational Raman spectral display at the polychromator exit plane. Spectral resolution is adequate to measure and correct for background in the Stokes spectrum. It is anticipated that this system should allow measurement of gas or atmospheric temperature to + or - 1 C
Increasing Sequential Compression Device Compliance to Decrease Venous Thromboembolisms and Improve Nursing Documentation
Venous thromboembolisms (VTE) affect approximately 350,000 to 900,000 people in the United States annually and are the leading cause to preventable hospital death (Centers for Disease Control [CDC], 2017). Nearly 70% of these cases were preventable through the use of pharmacologic agents and/or mechanical compression devices, such as sequential compression devices (SCD). However, less than half of hospitalized patients receive VTE prophylaxis (CDC, 2017). At a large metropolitan hospital, compliance with VTE prophylaxis, specifically with SCDs, is an ongoing quality improvement project. Currently, SCD usage and nursing documentation compliance have been consistently below performance standards. Therefore, the aim of this quality improvement project is to increase SCD compliance in order to decrease the incidence of VTEs and improve nursing documentation. Based on previous data from a root cause analysis, one of the pivotal contributing factors to low SCD compliance was the lack of available SCD machines. In order to overcome this barrier, 180 SCD machines were place at the end of each patient bed across all medical-surgical units. Additionally, in-services were conducted to educate day and night shift medical-surgical nurses on the importance of VTE prevention, new SCD protocols, and were reminded to document SCDs. Audits were conducted to evaluate the effectiveness of these interventions. Results showed that having SCDs at the point of care did not increase SCD usage and nursing education did not improve SCD documentation compliance. These results led students to investigate other contributing factors, such as physicians. Future recommendations for this project are to conduct a six-month post audit to examine the location of SCD machines, work closely with physicians to study other contributing factors to low SCD compliance, and compose additional SCD procedures to close gaps in the current protocol
A first-principles study of tunneling magnetoresistance in Fe/MgAl2O4/Fe(001) magnetic tunnel junctions
We investigated the spin-dependent transport properties of Fe/MgAl2O4/Fe(001)
magnetic tunneling junctions (MTJs) on the basis of first-principles
calculations of the electronic structures and the ballistic conductance. The
calculated tunneling magnetoresistance (TMR) ratio of a Fe/MgAl2O4/Fe(001) MTJ
was about 160%, which was much smaller than that of a Fe/MgO/Fe(001) MTJ
(1600%) for the same barrier thickness. However, there was an evanescent state
with delta 1 symmetry in the energy gap around the Fermi level of normal spinel
MgAl2O4, indicating the possibility of a large TMR in Fe/MgAl2O4/Fe(001) MTJs.
The small TMR ratio of the Fe/MgAl2O4/Fe(001) MTJ was due to new conductive
channels in the minority spin states resulting from a band-folding effect in
the two-dimensional (2-D) Brillouin zone of the in-plane wave vector (k//) of
the Fe electrode. Since the in-plane cell size of MgAl2O4 is twice that of the
primitive in-plane cell size of bcc Fe, the bands in the boundary edges are
folded, and minority-spin states coupled with the delta 1 evanescent state in
the MgAl2O4 barrier appear at k//=0, which reduces the TMR ratio of the MTJs
significantly.Comment: 5 pages, 6 figures, 1 tabl
Optimum element density studies for finite-element thermal analysis of hypersonic aircraft structures
Different finite element models previously set up for thermal analysis of the space shuttle orbiter structure are discussed and their shortcomings identified. Element density criteria are established for the finite element thermal modelings of space shuttle orbiter-type large, hypersonic aircraft structures. These criteria are based on rigorous studies on solution accuracies using different finite element models having different element densities set up for one cell of the orbiter wing. Also, a method for optimization of the transient thermal analysis computer central processing unit (CPU) time is discussed. Based on the newly established element density criteria, the orbiter wing midspan segment was modeled for the examination of thermal analysis solution accuracies and the extent of computation CPU time requirements. The results showed that the distributions of the structural temperatures and the thermal stresses obtained from this wing segment model were satisfactory and the computation CPU time was at the acceptable level. The studies offered the hope that modeling the large, hypersonic aircraft structures using high-density elements for transient thermal analysis is possible if a CPU optimization technique was used
Phase diagram of an exactly solvable t-J ladder model
We study a system of one-dimensional t-J models coupled to a ladder system. A
special choice of the interaction between neighbouring rungs leads to an
integrable model with supersymmetry, which is broken by the presence of rung
interactions. We analyze the spectrum of low-lying excitations and ground state
phase diagram at zero temperature.Comment: LaTeX, 8 pp. incl. 1 figur
Modulation of aldehyde dehydrogenase activitiy and retinoid signaling induces hematopoietic stem cell self renewal
Preventing dentures and putting aside the fry bread: A systematic review of micro, mezzo, and macro conditions for dental health and obesity interventions for Native American youth
This systematic literature review was focused on childhood obesity and dental health interventions which have relevance to Native American communities. Childhood oral health and obesity have become significant problems across North America and among Nati
Phase diagram of the su(8) quantum spin tube
We calculate the phase diagram of an integrable anisotropic 3-leg quantum
spin tube connected to the su(8) algebra. We find several quantum phase
transitions for antiferromagnetic rung couplings. Their locations are
calculated exactly from the Bethe Ansatz solution and we discuss the nature of
each of the different phases.Comment: 10 pages, RevTeX, 1 postscript figur
Third Neighbor Correlators of Spin-1/2 Heisenberg Antiferromagnet
We exactly evaluate the third neighbor correlator and all
the possible non-zero correlators <S^{alpha}_j S^{beta}_{j+1} S^{gamma}_{j+2}
S^{delta}_{j+3}> of the spin-1/2 Heisenberg antiferromagnet in the ground
state without magnetic field. All the correlators are expressed in terms of
certain combinations of logarithm ln2, the Riemann zeta function zeta(3),
zeta(5) with rational coefficients. The results accurately coincide with the
numerical ones obtained by the density-matrix renormalization group method and
the numerical diagonalization.Comment: 4 page
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