1,561 research outputs found
A Computer Simulation Model of Waterhyacinth and Weevil Interactions
A personal computer simulation model termed INSECT has been developed to evaluate biological control of waterhyacinth (Eichhornia crassipes (Mart.) Solms.) by two species of weevil (Neochetina eichhorniae Warner, and N. bruchi Hustache). The model results were compared with the data from three different locations. For each data set, the simulated plant biomass, adult and larva populations were plotted aqainst the 95% confidence intervals of the actual field observations. In many cases, the simulation results were within the 95% confidence intervals, and especially during the growing season, they indicated trends similar to those seen in the field data. However, there were discrepancies in both the magnitude and the trend for early and the late periods of the year. These initial results suggest that development of a model to simulate the impact of a biocontrol agent on waterhyacinth populations is a feasible approach to better understand the interactions within this control system
Wide-range optical studies on various single-walled carbon nanotubes: the origin of the low-energy gap
We present wide-range (3 meV - 6 eV) optical studies on freestanding
transparent carbon nanotube films, made from nanotubes with different diameter
distributions. In the far-infrared region, we found a low-energy gap in all
samples investigated. By a detailed analysis we determined the average
diameters of both the semiconducting and metallic species from the near
infrared/visible features of the spectra. Having thus established the
dependence of the gap value on the mean diameter, we find that the frequency of
the low energy gap is increasing with increasing curvature. Our results
strongly support the explanation of the low-frequency feature as arising from a
curvature-induced gap instead of effective medium effects. Comparing our
results with other theoretical and experimental low-energy gap values, we find
that optical measurements yield a systematically lower gap than tunneling
spectroscopy and DFT calculations, the difference increasing with decreasing
diameter. This difference can be assigned to electron-hole interactions.Comment: 9 pages, 8 figures, to be published in Physical Review B,
supplemental material attached v2: Figures 1, 7 and 8 replaced, minor changes
to text; v3: Figures 3, 4 and 5 replaced, minor changes to tex
Mining the TRAF6/p62 interactome for a selective ubiquitination motif
A new approach is described here to predict ubiquitinated substrates of the E3 ubiquitin ligase, TRAF6, which takes into account its interaction with the scaffold protein SQSTM1/p62. A novel TRAF6 ubiquitination motif defined as [–(hydrophobic)–k–(hydrophobic)–x–x–(hydrophobic)– (polar)–(hydrophobic)–(polar)–(hydrophobic)] was identified and used to screen the TRAF6/p62 interactome composed of 155 proteins, that were either TRAF6 or p62 interactors, or a negative dataset, composed of 54 proteins with no known association to either TRAF6 or p62. NRIF (K19), TrkA (K485), TrkB (K811), TrkC (K602 and K815), NTRK2 (K828), NTRK3 (K829) and MBP (K169) were found to possess a perfect match for the amino acid consensus motif for TRAF6/p62 ubiquitination. Subsequent analyses revealed that this motif was biased to the C-terminal regions of the protein (nearly 50% the sites), and had preference for loops (~50%) and helices (~37%) over beta-strands (15% or less). In addition, the motif was observed to be in regions that were highly solvent accessible (nearly 90%). Our findings suggest that specific Lysines may be selected for ubiquitination based upon an embedded code defined by a specific amino acid motif with structural determinants. Collectively, our results reveal an unappreciated role for the scaffold protein in targeting ubiquitination. The findings described herein could be used to aid in identification of other E3/scaffold ubiquitination sites
YF-17/ADEN system study
The YF-17 aircraft was evaluated as a candidate nonaxisymmetric nozzle flight demonstrator. Configuration design modifications, control system design, flight performance assessment, and program plan and cost we are summarized. Two aircraft configurations were studied. The first was modified as required to install only the augmented deflector exhaust nozzle (ADEN). The second one added a canard installation to take advantage of the full (up to 20 deg) nozzle vectoring capability. Results indicate that: (1) the program is feasible and can be accomplished at reasonable cost and low risk; (2) installation of ADEN increases the aircraft weight by 600 kg (1325 lb); (3) the control system can be modified to accomplish direct lift, pointing capability, variable static margin and deceleration modes of operation; (4) unvectored thrust-minus-drag is similar to the baseline YF-17; and (5) vectoring does not improve maneuvering performance. However, some potential benefits in direct lift, aircraft pointing, handling at low dynamic pressure and takeoff/landing ground roll are available. A 27 month program with 12 months of flight test is envisioned, with the cost estimated to be 13.2 million for the version without canard. The feasiblity of adding a thrust reverser to the YF-17/ADEN was investigated
Magneto-optical behaviour of EuIn_2P_2
We report results of a magneto-optical investigation of the Zintl-phase
compound EuInP. The compound orders magnetically at =24 K and
exhibits concomitant large magnetoresistance effects. For 50 K and
increasing magnetic fields we observe a transfer of spectral weight in
from energies above 1 eV into the low-energy metallic
component as well as into a mid-infrared signal centered at about 600
cm. This latter absorption is reminiscent to what has been seen in a
large variety of so-called Kondo materials and ascribed to excitations across
the hybridization gap. The observed gain of Drude weight upon increasing
magnetic field suggests an enhancement of the itinerant charge-carrier
concentration due to the increasing magnetization, a phenomenon that was
previously observed in other compounds which exhibit colossal magnetoresistive
effects.Comment: 13 pages, 4 figure
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Predictors of Acute Liver Failure in Patients With Acute Hepatitis A: An Analysis of the 2016-2018 San Diego County Hepatitis A Outbreak.
Background:Between 2016 and 2018, San Diego County experienced a hepatitis A outbreak with a historically high mortality rate (3.4%) that highlighted the need for early recognition of those at risk of developing acute liver failure (ALF). Methods:A retrospective case series of adult hospitalized patients with acute hepatitis A. Results:One hundred six patients with hepatitis A were studied, of whom 11 (10.4%) developed ALF, of whom 7 (6.6%) died. A history of alcohol abuse, hyperbilirubinemia, hypoalbuminemia, hyponatremia, and anemia were associated with increased odds of developing ALF. Initial Maddrey's and Model of End-Stage Liver Disease Sodium (MELD-Na) scores were also associated with the development of ALF. Multivariable analysis showed that a higher initial MELD-Na score (odds ratio [OR], 1.205; 95% confidence interval [CI], 1.018-1.427) and a lower initial serum albumin concentration (OR, 9.35; 95% CI, 1.15-76.9) were associated with increased odds of developing ALF. Combining serum albumin and MELD-Na (SAM; C-statistic, 0.8878; 95% CI, 0.756-0.988) yielded a model that was not better than either serum albumin (C-statistic, 0.852; 95% CI, 0.675-0.976) or MELD-Na (C-statistic, 0.891; 95% CI, 0.784-0.968; P = .841). Finally, positive blood cultures were more common among patients with ALF compared with those without ALF (63.6% vs 4.3%; P < .00001). Conclusions:Hypoalbuminemia was associated with an increased risk of ALF in patients with acute hepatitis A. Positive blood cultures and septic shock as a cause of death were common among patients with ALF. Providers caring for patients with acute hepatitis A should monitor for early signs of sepsis and consider empiric antibiotics, especially in patients presenting with hypoalbuminemia
Optical evidence for a spin-filter effect in the charge transport of
We have measured the optical reflectivity of
as a function of temperature between 1.5 and 300
and in external magnetic fields up to 7 . The slope at the onset of the
plasma edge feature in increases with decreasing temperature and
increasing field but the plasma edge itself does not exhibit the remarkable
blue shift that is observed in the binary compound . The analysis of
the magnetic field dependence of the low temperature optical conductivity
spectrum confirms the previously observed exponential decrease of the
electrical resistivity upon increasing, field-induced bulk magnetization at
constant temperature. In addition, the individual exponential magnetization
dependences of the plasma frequency and scattering rate are extracted from the
optical data.Comment: submitted to Phys. Rev. Let
Development and Initial Psychometric Evaluation of the Computer-Based Prostate Cancer Screening Decision Aid Acceptance Scale for African-American Men
BACKGROUND:
To reliably evaluate the acceptance and use of computer-based prostate cancer decision aids (CBDAs) for African-American men, culturally relevant measures are needed. This study describes the development and initial psychometric evaluation of the 24-item Computer-Based Prostate Cancer Screening Decision Aid Acceptance Scale among 357 African-American men.
METHODS:
Exploratory factor analysis (EFA) with maximum likelihood estimation and polychoric correlations followed by Promax and Varimax rotations. RESULTS: EFA yielded three factors: Technology Use Expectancy and Intention (16 items), Technology Use Anxiety (5 items), and Technology Use Self-Efficacy (3 items) with good to excellent internal consistency reliability at .95, .90, and .85, respectively. The standardized root mean square residual (0.035) indicated the factor structure explained most of the correlations.
CONCLUSIONS:
Findings suggest the three-factor, 24-item Computer-Based Prostate Cancer Screening Decision Aid Acceptance Scale has utility in determining the acceptance and use of CBDAs among African-American men at risk for prostate cancer. Future research is needed to confirm this factor structure among socio-demographically diverse African-Americans
Optical investigations on : Electronic structure evolutions related to the metal-insulator transition
Optical conductivity spectra of cubic pyrochlore
(0.0{\it x}2.0) compounds are investigated. As a metal-insulator
transition (MIT) occurs around {\it x}0.8, large spectral changes are
observed. With increase of {\it x}, the correlation-induced peak between the
lower and the upper Hubbard bands seems to be suppressed, and a strong
mid-infrared feature is observed. In addition, the charge transfer peak
shifts to the lower energies. The spectral changes cannot be explained by
electronic structural evolutions in the simple bandwidth-controlled MIT
picture, but are consistent with those in the filling-controlled MIT picture.
In addition, they are also similar to the spectral changes of
YCaRuO compounds, which is a typical
filling-controlled system. This work suggests that, near the MIT, the Ru bands
could be doped with the easily polarizable Bi cations.Comment: 5 figure
Supermetallic conductivity in bromine-intercalated graphite
Exposure of highly oriented pyrolytic graphite to bromine vapor gives rise to
in-plane charge conductivities which increase monotonically with intercalation
time toward values (for ~6 at% Br) that are significantly higher than Cu at
temperatures down to 5 K. Magnetotransport, optical reflectivity and magnetic
susceptibility measurements confirm that the Br dopes the graphene sheets with
holes while simultaneously increasing the interplanar separation. The increase
of mobility (~ 5E4 cm^2/Vs at T=300 K) and resistance anisotropy together with
the reduced diamagnetic susceptibility of the intercalated samples suggests
that the observed supermetallic conductivity derives from a parallel
combination of weakly-coupled hole-doped graphene sheets.Comment: 5 pages, 4 figure
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