National trends in the United States of America physician assistant workforce from 1980 to 2007

<p>Abstract</p> <p>Background</p> <p>The physician assistant (PA) profession is a nationally recognized medical profession in the United States of America (USA). However, relatively little is known regarding national trends of the PA workforce.</p> <p>Methods</p> <p>We examined the 1980-2007 USA Census data to determine the demographic distribution of the PA workforce and PA-to-population relationships. Maps were developed to provide graphical display of the data. All analyses were adjusted for the complex census design and analytical weights provided by the Census Bureau.</p> <p>Results</p> <p>In 1980 there were about 29 120 PAs, 64% of which were males. By contrast, in 2007 there were approximately 97 721 PAs with more than 66% of females. In 1980, Nevada had the highest estimated rate of 40 PAs per 100 000 persons, and North Dakota had the lowest rate (three). The corresponding rates in 2007 were about 85 in New Hampshire and ten in Mississippi. The levels of PA education have increased from less than 21% of PAs with four or more years of college in 1980, to more than 65% in 2007. While less than 17% of PAs were of minority groups in 1980, this figure rose to 23% in 2007. Although nearly 70% of PAs were younger than 35 years old in 1980, this percentage fell to 38% in 2007.</p> <p>Conclusion</p> <p>The trends of sustained increase and geographic variation in the PA workforce were identified. Educational level, percentage of minority, and age of the PA workforce have increased over time. Major causes of the changes in the PA workforce include educational factors and federal legislation or state regulation.</p

Miniaturization Design for 8 × 8 Butler Matrix Based on Back-to-Back Bilayer Microstrip

A low-cost, compact 8 × 8 Butler matrix based on a novel bilayer microstrip configuration is presented and implemented for 4.3 GHz telecommunication application. A back-to-back placed bilayer microstrip structure has been proposed to avoid using crossover. To expand operational bandwidth of the Butler matrix, a three-branch line directional coupler has been employed as 3 dB/90° bridge, and a kind of improved two-order Schiffman phase shifter has been adopted as fixed phase shifter. For application of indoor wireless communication, a compact broadband 8 × 8 Butler matrix has been designed and fabricated. The measured results show that the return loss of the matrix is lower than −10 dB, the isolation is better than 17 dB, the power distribution error is less than ±2.0 dB, the phase error is less than ±15°, and the relative bandwidth is more than 23%

Spatial Variations of Stochastic Noise Properties in GPS Time Series

The noise in position time series of 568 GPS (Global Position System) stations across North America with an observation span of ten years has been investigated using solutions from two processing centers, namely, the Pacific Northwest Geodetic Array (PANGA) and New Mexico Tech (NMT). It is well known that in the frequency domain, the noise exhibits a power-law behavior with a spectral index of around −1. By fitting various noise models to the observations and selecting the most likely one, we demonstrate that the spectral index in some regions flattens to zero at long periods while in other regions it is closer to −2. This has a significant impact on the estimated linear rate since flattening of the power spectral density roughly halves the uncertainty of the estimated tectonic rate while random walk doubles it. Our noise model selection is based on the highest log-likelihood value, and the Akaike and Bayesian Information Criteria to reduce the probability of over selecting noise models with many parameters. Finally, the noise in position time series also depends on the stability of the monument on which the GPS antenna is installed. We corroborate previous results that deep-drilled brace monuments produce smaller uncertainties than concrete piers. However, if at each site the optimal noise model is used, the differences become smaller due to the fact that many concrete piers are located in tectonic/seismic quiet areas. Thus, for the predicted performance of a new GPS network, not only the type of monument but also the noise properties of the region need to be taken into account

Effects of increased phosphorus fertilizer on C, N, and P stoichiometry in different organs of bluegrass (Poa L.) at different growth stages

IntroductionThe application of phosphorus (P) fertilizer can promote photosynthesis in forage grasses and accelerate their establishment.MethodsTo improve the utilization efficiency of P fertilizer for bluegrass (Poa L.) in alpine regions, the effects of P fertilizer on their growth, and carbon (C), nitrogen (N) and P distribution in their different organs of them are tested at six P fertilization levels (3, 6, 9, 12, 15, 18 g·m−2).Results(1) The nutrient content in each organ of bluegrass varies during different growth stages, with the lowest nutrient content occurring in the wilt stage. (2) The response of the nutrient content and ratio of each organ of bluegrass to different P fertilization levels varies. When the P application rate was 15 g·m−2, the contents of N and P in roots were the highest, and their C/N and C/P ratios were the lowest. When the P application rate was 12 g·m−2, the contents of N and P in the stems were the highest, and their C/N and C/P ratios were the lowest. When the P application rate was 9 g·m−2, the contents of N and P in leaves were the highest, and their C/N and C/P ratios were the lowest. When the P application rate was 6 g·m−2 the contents of N and P in the panicle were the highest, and their C/N and C/P ratios were the lowest.DiscussionThese results provide a better understanding of the effect of P fertilization in the nutrient partitioning pattern of perennial forage plant organs in alpine regions. The information from this study can support a more reasonable P fertilization for the establishment of early grassland. For example, in artificial forage grassland, the application of low-concentration P fertilizer (6~9 g·m−2) can promote the nutrient content in spikes and stems of forage grass; for ecological management, the application of high-concentration P fertilizer (15 g·m−2) can promote the nutrient content in roots and enhance the ecological benefits of forage grassland

Sea Level Rise Estimation on the Pacific Coast from Southern California to Vancouver Island

Previous studies have estimated the sea level rise (SLR) at various locations on the west coast of the USA and Vancouver Island in Canada. Here, we construct an entire SLR profile from Vancouver Island in the Pacific Northwest to San Diego in Southern California. First, we process global navigation satellite system (GNSS) measurements at 405 stations blanketing the whole coast to generate a profile of vertical land motion (VLM) known to bias century-long tide gauge (TG) measurements recording relative SLR (RSLR). We are then able to estimate the absolute SLR (ASLR) by correcting the SLR with the VLM. Our study emphasizes the relationship between the various tectonic movements (i.e., the Cascadia subduction zone, the San Andreas strike-slip fault system) along the Pacific coast which renders it difficult to accurately estimate the SLR. That is why we precisely model the stochastic noise of both GNSS and tide gauge time series using a combination of various models and information criterions (ICs). We also use the latest altimetry products and sea surface height (SSH) to compare it with ASLR at the same location as the TGs. This study supports previous analysis that the power law + white noise and generalized Gauss–Markov + white noise models are the best stochastic noise models for the GNSS time series. The new coastal profile confirms the large variability of VLM estimates in the Pacific Northwest around the Cascadia subduction zone in agreement with previous studies, and a similar result when the San Andreas fault comes onshore in Central California (San Francisco Bay). Negative RSLR values are mostly located in the Pacific Northwest (Vancouver Island and Olympic Peninsula). We also observe a much bigger variation (about 90–150%) of the ASLR in the Pacific Northwest which is predominantly due to glacial isostatic adjustment (GIA). Moreover, the comparison between the ASLR and the SSH estimates shows similarities in the center of the studied area (South Washington, Oregon planes, and some parts of Southern California) where the tectonic activity does not significantly influence the TG measurements. Finally, the twentieth-century satellite geocentric ocean height rates show a global mean of 1.5 to 1.9 mm/yr. Our estimates based on ASLR and SSH are within this interval

Characterization of Bacillus amyloliquefaciens BA-4 and its biocontrol potential against Fusarium-related apple replant disease

Apple replant disease (ARD), caused by Fusarium pathogens, is a formidable threat to the renewal of apple varieties in China, necessitating the development of effective and sustainable control strategies. In this study, the bacterial strain BA-4 was isolated from the rhizosphere soil of healthy apple trees in a replanted orchard, demonstrating a broad-spectrum antifungal activity against five crucial apple fungal pathogens. Based on its morphology, physiological and biochemical traits, utilization of carbon sources, and Gram stain, strain BA-4 was tentatively identified as Bacillus amyloliquefaciens. Phylogenetic analysis using 16S rDNA and gyrB genes conclusively identified BA-4 as B. amyloliquefaciens. In-depth investigations into B. amyloliquefaciens BA-4 revealed that the strain possesses the capacity to could secrete cell wall degrading enzymes (protease and cellulase), produce molecules analogous to indole-3-acetic acid (IAA) and siderophores, and solubilize phosphorus and potassium. The diverse attributes observed in B. amyloliquefaciens BA-4 underscore its potential as a versatile microorganism with multifaceted benefits for both plant well-being and soil fertility. The extracellular metabolites produced by BA-4 displayed a robust inhibitory effect on Fusarium hyphal growth and spore germination, inducing irregular swelling, atrophy, and abnormal branching of fungal hyphae. In greenhouse experiments, BA-4 markedly reduced the disease index of Fusarium-related ARD, exhibiting protective and therapeutic efficiencies exceeding 80% and 50%, respectively. Moreover, BA-4 demonstrated plant-promoting abilities on both bean and Malus robusta Rehd. (MR) seedlings, leading to increased plant height and primary root length. Field experiments further validated the biocontrol effectiveness of BA-4, demonstrating its ability to mitigate ARD symptoms in MR seedlings with a notable 33.34% reduction in mortality rate and improved biomass. Additionally, BA-4 demonstrates robust and stable colonization capabilities in apple rhizosphere soil, particularly within the 10-20 cm soil layer, which indicates that it has long-term effectiveness potential in field conditions. Overall, B. amyloliquefaciens BA-4 emerges as a promising biocontrol agent with broad-spectrum antagonistic capabilities, positive effects on plant growth, and strong colonization abilities for the sustainable management of ARD in apple cultivation

Enhanced photodegradation activity of methyl orange over Z-scheme type MoO3-g-C3N4 composite under visible light irradiation

National Natural Science Foundation of China [21003109, 51108424]; Opening-foundation of State Key Laboratory Physical Chemistry and Solid Surfaces, Xiamen University, China [201311]; School of Energy Resources at University of WyomingNovel Z-scheme type MoO3-g-C3N4 composites photocatalysts were prepared with a simple mixing-calcination method, and evaluated for their photodegradation activities of methyl orange (MO). The optimized MoO3-g-C3N4 photocatalyst shows a good activity with a kinetic constant of 0.0177 min(-1), 10.4 times higher than that of g-C3N4. Controlling various factors (MoO3-g-C3N4 amount, initial MO concentration, and pH value of MO solution) can lead to the enhancement of the photocatalytic activity of the composite. Only MoO3 and g-C3N4 are detected with X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) spectra. N-2 adsorption and UV-vis diffuse reflectance spectroscopy (DRS) results suggest that the addition of MoO3 slightly affects the specific surface area and the photoabsorption performance. The transmission electron microscopy (TEM) image of MoO3-g-C3N4 indicates a close contact between MoO3 and g-C3N4, which is beneficial to interparticle electron transfer. The high photocatalytic activity of MoO3-g-C3N4 is mainly attributed to the synergetic effect of MoO3 and g-C3N4 in electron-hole pair separation via the charge migration between the two semiconductors. The charge transfer follows direct Z-scheme mechanism, which is proven by the reactive species trapping experiment and the (OH)-O-center dot-trapping photoluminescence spectra

Photodegradation of RhB over YVO4/g-C3N4 composites under visible light irradiation

National Natural Science Foundation of China [21003109, 51108424]; Opening-foundation of State Key Laboratory Physical Chemistry and Solid Surfaces, Xiamen University, China [201311]; Science Foundation of Zhejiang Normal University [KJ20120028]A series of novel YVO4/g-C3N4 photocatalysts were prepared by a facile mixing and calcination method. The obtained composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, ultraviolet visible diffuse reflection spectroscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, and a photocurrent-time experiment. The rhodamine B dye was selected as a model pollutant to evaluate the photocatalytic activity of the as-prepared YVO4/g-C3N4 composite. It shows that the photocatalytic activity of g-C3N4 can be largely improved by the doping of YVO4. The optimal YVO4 content is determined to be 25.8 wt%; and the corresponding degradation rate is 2.34 h(-1), about 2.75 folds that of pure g-C3N4. A possible mechanism of YVO4 on the enhancement of visible light performance is proposed. It suggests that YVO4 plays a key role, which may lead to efficiently suppressing the recombination of photogenerated charge carriers, consequently, improving the visible light photoactivity

Interaction of Mesoporous Silica Nanoparticles with Human Red Blood Cell Membranes: Size and Surface Effects

The interactions of mesoporous silica nanoparticles (MSNs) of different particle sizes and surface properties with human red blood cell (RBC) membranes were investigated by membrane filtration, flow cytometry, and various microscopic techniques. Small MCM-41-type MSNs (∼100 nm) were found to adsorb to the surface of RBCs without disturbing the membrane or morphology. In contrast, adsorption of large SBA-15-type MSNs (∼600 nm) to RBCs induced a strong local membrane deformation leading to spiculation of RBCs, internalization of the particles, and eventual hemolysis. In addition, the relationship between the degree of MSN surface functionalization and the degree of its interaction with RBC, as well as the effect of RBC−MSN interaction on cellular deformability, were investigated. The results presented here provide a better understanding of the mechanisms of RBC−MSN interaction and the hemolytic activity of MSNs and will assist in the rational design of hemocompatible MSNs for intravenous drug delivery and in vivo imaging