3,425 research outputs found
Craniofacial diversification in the domestic pigeon and the evolution of the avian skull.
A central question in evolutionary developmental biology is how highly conserved developmental systems can generate the remarkable phenotypic diversity observed among distantly related species. In part, this paradox reflects our limited knowledge about the potential for species to both respond to selection and generate novel variation. Consequently, the developmental links between small-scale microevolutionary variations within populations to larger macroevolutionary patterns among species remain unbridged. Domesticated species, such as the pigeon, are unique resources for addressing this question, because a history of strong artificial selection has significantly increased morphological diversity, offering a direct comparison of the developmental potential of a single species to broader evolutionary patterns. Here, we demonstrate that patterns of variation and covariation within and between the face and braincase in domesticated breeds of the pigeon are predictive of avian cranial evolution. These results indicate that selection on variation generated by a conserved developmental system is sufficient to explain the evolution of crania as different in shape as the albatross or eagle, parakeet or hummingbird. These 'rules' of cranio-facial variation are a common pattern in the evolution of a broad diversity of vertebrate species and may ultimately reflect structural limitations of a shared embryonic bauplan on functional variation
Inflammation and dietary protein intake exert competing effects on serum albumin and creatinine in hemodialysis patients
Inflammation and dietary protein intake exert competing effects on serum albumin and creatinine in hemodialysis patients.BackgroundCross-sectional studies have shown an inverse correlation between serum C-reactive protein (CRP) and serum albumin concentration in hemodialysis patients. The net effects of inflammation and dietary protein intake on nutritional markers over time are unknown.MethodsTo explore the effects of CRP and normalized protein catabolic rate (nPCR) on serum albumin and creatinine, we analyzed six consecutive months of laboratory data from 364 hemodialysis patients, using a multivariable Mixed model with conservative biases.ResultsThe overall trend over time in serum albumin was slightly positive (0.039 g/dL/month) and in serum creatinine slightly negative (-0.052 mg/dL/month). With increasing CRP, serum albumin declined significantly (-0.124 g/dL/month per unit increase in log CRP, adjusted for age, gender, race, diabetes, and nPCR, P < 0.0001). Serum albumin increased with increasing nPCR (0.021 g/dL/month per 0.1 g/kg/day, P < 0.0001). The effect of CRP on albumin was attenuated in African Americans and at a higher nPCR. Corresponding values for creatinine mirrored those for albumin. With increasing CRP, creatinine declined significantly [-0.142 mg/dL/month per unit increase in log CRP, adjusted for age, gender, race, diabetes (time since initiation of dialysis; vintage), Kt/V, and nPCR, P = 0.002]. Serum creatinine increased with increasing nPCR (0.183 mg/dL/month per g/kg/day, P < 0.0001).ConclusionsProxies of inflammation and dietary protein intake exert competing effects on serum albumin and creatinine in hemodialysis patients. These data provide a rationale for prospective testing of dietary protein supplementation in hemodialysis patients with biochemical evidence of ongoing inflammation and “malnutrition.
The validity and scalability of the theory-of-mind scale with toddlers and pre-schoolers
Despite the importance of theory of mind (ToM) for typical development, there remain two key issues affecting our ability to draw robust conclusions. One is the continued focus on false-belief as the sole measure of ToM. The second is the lack of empirically validated measures of ToM as a broad construct. Our key aim was to examine the validity and reliability of the five-item ToM scale (Peterson, Wellman, & Lui, 2005). In particular, we extended on previous research of this scale by assessing its scalability and validity for use with children from two years of age. Sixty-eight typically developing children (aged 24 to 61 months) were assessed on the scale’s five tasks, along with a sixth Sally-Anne false-belief task. Our data replicated the scalability of the five tasks for a Rasch- but not Guttman-scale. Guttman analysis showed a four-item scale may be more suitable for this age range. Further, the tasks showed good internal consistency and validity for use with children as young as two years of age. Overall, the measure provides a valid and reliable tool for the assessment of ToM, and in particular the longitudinal assessment of this ability as a construct
An atomic boson sampler
A boson sampler implements a restricted model of quantum computing. It is
defined by the ability to sample from the distribution resulting from the
interference of identical bosons propagating according to programmable,
non-interacting dynamics. Here, we demonstrate a new combination of tools for
implementing boson sampling using ultracold atoms in a two-dimensional,
tunnel-coupled optical lattice. These tools include fast and programmable
preparation of large ensembles of nearly identical bosonic atoms
( indistinguishability) by means of rearrangement with
optical tweezers and high-fidelity optical cooling, propagation for variable
evolution time in the lattice with low loss (, independent of
evolution time), and high fidelity detection of the atom positions after their
evolution (typically ). With this system, we study specific
instances of boson sampling involving up to atoms distributed among sites in the lattice. Direct verification of a given boson sampling
distribution is not feasible in this regime. Instead, we introduce and perform
targeted tests to determine the indistinguishability of the prepared atoms, to
characterize the applied family of single particle unitaries, and to observe
expected bunching features due to interference for a large range of atom
numbers. When extended to interacting systems, our work demonstrates the core
capabilities required to directly assemble ground and excited states in
simulations of various Hubbard models.Comment: 20 pages, 7 figures (main text and methods); 8 pages, 2 figures
(supplemental materials
Recommended from our members
The Influence of Fire on a Rare Serpentine Plant Assemblage: A Five Year Study of Darlingtonia Fens
Premise of the study: Serpentine soils have attracted the attention of evolutionary biologists for decades due to their high number of rare and endemic taxa, though less is known about the ecological factors that govern the diversity and composition of serpentine communities. Theory suggests that vegetation on these low-productivity soils will be relatively resilient to fire, the most common natural disturbance in serpentine systems. Methods: We studied the recovery of vegetation in Darlingtonia fens, a unique habitat dominated by herbaceous perennials, from a major fire that burned ~202,000 hectares in California and Oregon’s Klamath Mountains in 2002. We established permanent plots in 8 unburned and 8 burned fens in 2003 and recorded percent cover of vascular plant species. We re-sampled plots each year through 2007. Key results: Burned fens had less plant cover than unburned fens for two years after the fire. Average species density was ~10% lower in burned fens one year after the fire but ~4-8% higher for the next four years. Burned fens exhibited greater evenness, but not until four years after the fire. Differences in community composition were detected between the two fen types, but species ranks were similar, and species neither were added to, nor removed from, the burned assemblages. Conclusions: Burning of Darlingtonia fens has detectable, albeit modest effects on serpentine communities. Because fens have little or no canopy cover, fire has little influence on light availability in this system. This relatively small resource change, combined with high soil moisture and well-developed underground organs of fen plants, produces a highly resilient assemblage.Organismic and Evolutionary BiologyOther Research Uni
Shining a LAMP on the applications of isothermal amplification for monitoring environmental biosecurity
Environmental biosecurity risks associated with the transnational wildlife trade include the loss of biodiversity, threats to public health, and the proliferation of invasive alien species. To assist enforcement agencies in identifying species either intentionally (trafficked) or unintentionally (stowaway) entrained in the trade-chain pathway, rapid forensic techniques are needed to enable their detection from DNA samples when physical identification is not possible. Loop Mediated Isothermal Amplification (LAMP) is an emerging technique, with recent applications in biosecurity and forensic sciences, which has potential to function as a field-based detection tool. Here we provide an overview of current research that applies LAMP to environmental biosecurity, including identification of ornamental wildlife parts, consumer products, and invasive species monitoring and biosecurity detection. We discuss the current scope of LAMP as applied to various wildlife trade scenarios and biosecurity checkpoint monitoring, highlight the specificity, sensitivity, and robustness for these applications, and review the potential utility of LAMP for rapid field-based detection at biosecurity checkpoints. Based on our assessment of the literature we recommend broader interest, research uptake, and investment in LAMP as an appropriate field-based species detection method for a wide range of environmental biosecurity scenarios
- …