A new perspective on the spatial, environmental, and metacommunity controls of local biodiversity.

Influential ecological research in the 1980s, elucidating that local biodiversity (LB) is a function of local ecological factors and the size of the regional species pool (γ-diversity), has prompted numerous investigations on the local and regional origins of LB. These investigations, however, have been mostly limited to single scales and target groups and centered exclusively on γ-diversity. Here we developed a unified framework including scale, environmental factors (heterogeneity and ambient levels), and metacommunity properties (intraspecific spatial aggregation, regional evenness, and γ-diversity) as hierarchical predictors of LB.

Leveraging clinical decision support to reduce the risk of discordant pharmacogenomics results.

Pharmacogenomics (PGx) testing is commonly utilized to predict a patient's response to medications based on the presence of genetic variants. However, certain conditions have been associated with potentially inaccurate PGx results. The majority of medications are predominantly metabolized in the liver; therefore, in the case of liver transplantation, PGx results may be misinterpreted in the context of drug-metabolizing enzymes.

Zinc-Acetate-Amine Complexes as Precursors to ZnO and the Effect of the Amine on Nanoparticle Morphology, Size, and Photocatalytic Activity.

Zinc oxide is an environmentally friendly and readily synthesized semiconductor with many industrial applications. ZnO powders were prepared by alkali precipitation using different [Zn(acetate)(amine)] compounds to alter the particle size and aspect ratio. Slow precipitations from 95 °C solutions produced micron-scale particles with morphologies of hexagonal plates, rods, and needles, depending on the precursor used.

On the shape and origins of the freshwater species-area relationship.

The species-area relationship (SAR) has over a 150-year-long history in ecology, but how its shape and origins vary across scales and organisms remains incompletely understood. This is the first subcontinental freshwater study to examine both these properties of the SAR in a spatially explicit way across major organismal groups (diatoms, insects, and fish) that differ in body size and dispersal capacity. First, to describe the SAR shape, we evaluated the fit of three commonly used models, logarithmic, power, and Michaelis-Menten.

Flow pulses and fine sediments degrade stream macroinvertebrate communities in King County, Washington, USA.

Determining the causes of biological impairment in urban stream settings presents unique challenges because there are many potential stressors associated with human development. A rigorous, scientifically based process is more likely to identify influential stressors that can be reduced to improve stream condition. We used the U.

Niche dimensionality and herbivory control stream algal biomass via shifts in guild composition, richness, and evenness.

We developed a framework for the hierarchical pathways of bottom-up (niche dimensionality) and top-down control (herbivory) on biomass of stream algae via changes in guild composition (relative abundance of low profile, high profile, and motile guilds), species richness, and evenness. We further tested (1) the contrasting predictions of resource competition theory vs. the benthic model of coexistence on how the number of added nutrients constrains species richness, (2) the relationship between species richness and evenness, and (3) the biodiversity-ecosystem-function paradigm.

Biogeographical Patterns of Species Richness and Abundance Distribution in Stream Diatoms Are Driven by Climate and Water Chemistry.

In this intercontinental study of stream diatoms, we asked three important but still unresolved ecological questions: (1) What factors drive the biogeography of species richness and species abundance distribution (SAD)? (2) Are climate-related hypotheses, which have dominated the research on the latitudinal and altitudinal diversity gradients, adequate in explaining spatial biotic variability? and (3) Is the SAD response to the environment independent of richness? We tested a number of climatic theories and hypotheses (i.e., the species-energy theory, the metabolic theory, the energy variability hypothesis, and the climatic tolerance hypothesis) but found no support for any of these concepts, as the relationships of richness with explanatory variables were nonexistent, weak, or unexpected.

Iron limitation effects on nitrogen-fixing organisms with possible implications for cyanobacterial blooms.

Cyanobacteria-dominated harmful algal blooms are increasing in occurrence. Many of the taxa contributing to these blooms are capable of fixing atmospheric nitrogen and should be favored under conditions of low nitrogen availability. Yet, synthesizing nitrogenase, the enzyme responsible for nitrogen fixation, is energetically expensive and requires substantial concentrations of iron.

Midpalatal suture density ratio: A novel predictor of skeletal response to rapid maxillary expansion.

Introduction: During adolescence, increasing interdigitation of the midpalatal suture increases resistance to rapid maxillary expansion (RME); this decreases its skeletal effect. In this study, we aimed at determining whether a novel measure of midpalatal suture maturity, the midpalatal suture density ratio, can be used as a valid predictor of the skeletal response to RME.

Methods: The midpalatal suture density ratio, chronologic age, cervical vertebral maturation, and the stage of midpalatal suture maturation were assessed before treatment for 30 patients (ages, 12.

A Large-Scale, Multiagency Approach to Defining a Reference Network for Pacific Northwest Streams.

Aquatic monitoring programs vary widely in objectives and design. However, each program faces the unifying challenge of assessing conditions and quantifying reasonable expectations for measured indicators. A common approach for setting resource expectations is to define reference conditions that represent areas of least human disturbance or most natural state of a resource characterized by the range of natural variability across a region of interest.

The number of limiting resources in the environment controls the temporal diversity patterns in the algal benthos.

The role of the number of limiting resources (NLR) on species richness has been the subject of much theoretical and experimental work. However, how the NLR controls temporal beta diversity and the processes of community assembly is not well understood. To address this knowledge gap, we initiated a series of laboratory microcosm experiments, exposing periphyton communities to a gradient of NLR from 0 to 3, generated by supplementation with nitrogen, phosphorus, iron, and all their combinations.

Iron supply constrains producer communities in stream ecosystems.

The current paradigm that stream producers are under exclusive macronutrient control was recently challenged by continental studies, demonstrating that iron supply constrained diatom biodiversity and energy flows. Using algal abundance and water chemistry data from the National Water-Quality Assessment Program, we determined for the first time community thresholds along iron gradients in non-acidic running waters, i.e.

Rates of species accumulation and taxonomic diversification during phototrophic biofilm development are controlled by both nutrient supply and current velocity.

The accumulation of new and taxonomically diverse species is a marked feature of community development, but the role of the environment in this process is not well understood. To address this problem, we subjected periphyton in laboratory streams to low (10-cm · s(-1)), high (30-cm · s(-1)), and variable (9- to 32-cm · s(-1)) current velocity and low- versus high-nutrient inputs. We examined how current velocity and resource supply constrained (i) the rates of species accumulation, a measure of temporal beta-diversity, and (ii) the rates of diversification of higher taxonomic categories, defined here as the rate of higher taxon richness increase with the increase of species richness.

Biomechanical evaluation of the Total Facet Arthroplasty System® (TFAS®): loading as compared to a rigid posterior instrumentation system.

Purpose: To gain insight into a new technology, a novel facet arthroplasty device (TFAS) was compared to a rigid posterior fixation system (UCR). The axial and bending loads through the implants and at the bone-implant interfaces were evaluated using an ex vivo biomechanical study and matched finite element analysis. Kinematic behaviour has been reported for TFAS, but implant loads have not.

Taxonomic and functional composition of the algal benthos exhibits similar successional trends in response to nutrient supply and current velocity.

In an effort to identify the causes and patterns of temporal change in periphytic communities, we examined biomass accumulation, taxonomic and functional composition, rate of species turnover, and pairwise species correlations in response to variability in current velocity and nutrient supply in artificial stream flumes. Divergent patterns in community growth and succession were observed between nutrient treatments and, to a lesser extent, between flow treatments best described by shifts in taxonomic and functional composition. Specifically, understory low profile species, tolerant to low resource supply, became dominant under low nutrients, while overstory high profile and motile species with higher nutrient demands dominated the high nutrient treatments.

Succession in stream biofilms is an environmentally driven gradient of stress tolerance.

The century-long research on succession has bestowed us with a number of theories, but little agreement on what causes species replacements through time. The majority of studies has explored the temporal trends of individual species in plant and much less so in microbial communities, arguing that interspecific interactions, especially competition, play a key role in community organization throughout succession. In this experimental investigation of periphytic succession in re-circulating laboratory streams, we examined the density and the relative abundance of diatoms and soft algae for 35 days across gradients of low to high nutrient supply (nitrogen + phosphorus) and low to intermediate current velocity (10 vs.

Biomechanical evaluation of the Total Facet Arthroplasty System: 3-dimensional kinematics.

Study Design: An in vitro biomechanical study to quantify 3-dimensional kinematics of the lumbar spine following facet arthroplasty.

Objectives: To compare the multidirectional flexibility properties and helical axis of motion of the Total Facet Arthroplasty System (TFAS) (Archus Orthopedics, Redmond, WA) to the intact condition and to posterior pedicle screw fixation.

Summary Of Background Data: Facet arthroplasty in the lumbar spine is a new concept in the field of spinal surgery.