Habitat Distribution And Frond Reorientation As Photoprotection And Drought-Avoidance Mechanisms In Christmas Fern (Polystichum Acrostichoides) In The Southern Appalachian Mountains

Christmas fern (Polystichum acrostichoides (Michx.) Schott) is a ubiquitous wintergreen herb found in the forests of the Appalachian Mountains, yet it is distributed asymmetrically on the landscape, favoring north-facing slopes and shady stream banks. In late autumn, the fronds of Christmas fern undergo an irreversible reorientation, bending at the base of the stipe and lying flat on the forest floor. These fronds maintain high chlorophyll concentrations throughout winter and are photosynthetically active on warm winter days and in early spring before canopy emergence. In three populations in the Appalachian State University Biological Preserve, I prevented fronds from reorienting using wooden dowels and floral wire, artificially holding them up over winter. The fronds that were prevented from reorienting to a prostrate position suffered severe photoinhibition characterized by extensive leaf necrosis coupled with significant declines in light-saturated gas exchange, chlorophyll fluorescence (Fv/Fm), and total chlorophyll, while a control group showed little or no declines as winter progressed. “Surrogate ferns” were constructed and mounted with light sensors in order to characterize the light environment at the leaf level on north- and south- facing slopes. Inclined fronds experienced much higher light levels than prostrate fronds (oriented horizontally), on both slopes, and the sensor on the south-facing slope experienced 22 days in which light exceeded 500 µmol m-2 s-1 and the air temperature at the leaf level was below freezing. Conversely, on the north-facing slope, these conditions only occurred on one day. This result suggests that frond reorientation is sufficient to prevent photoinhibition in overwintering fronds of Christmas fern by reducing winter light, and may be a significant factor limiting its distribution on south-facing slopes where it is bright and cold during winter. Christmas ferns demonstrated remarkable resilience in a controlled dry-down, with little physiological decline as midday water potentials exceeded -1.0 MPa and soil water content approached 0%. Presently, it is unclear how fern water relations contribute to frond reorientation or distribution on the landscape, but the microclimate data suggest that south- facing slopes are not dry enough to induce significant physiological stress on Christmas fern, and that winter light may have more influence. Forecasted changes in local climate may alter the range and distribution of Christmas fern. Our results provide insight into how this species might be affected, with significant ecological implications for understory herbs in our region

Reproduction and opportunity: A study of dual career, aspirations and elite sports in Danish SportsClasses

This paper analyzes the patterns of retention in SportsClasses of promising young athletes in Denmark. Since 2005, SportsClasses have provided extra training for potential elite athletes in Grades 7-9 in designated Danish public schools. They were introduced after the Danish Ministry of Culture lowered the age of recruitment for athletes from 15 to 12 in response to increased competition in the world of elite sports. The SportsClasses attempt to balance collaboration between two different organizations: Danish public schools and sports clubs. Using a survey of the student population in 2013 and a follow-up sample in 2015, we explore the respondents’ social backgrounds and experiences in order to understand their likelihood of retention during the program and their career aspirations. Focusing on socioeconomic status, the role of having parents in elite sports, gender, and type of sport, we study what key experiences and relationships lead students to abandon or sustain their interest in careers related to sports and how this differs for boys and girls. By applying Bourdieu’s concepts of habitus and types of capital, we conclude that the program produces elements of both reproduction and opportunity but that the patterns strongly favor the retention of boys compared to girls

Reproduction and opportunity: A study of dual career, aspirations and elite sports in Danish SportsClasses

This paper analyzes the patterns of retention in SportsClasses of promising young athletes in Denmark. Since 2005, SportsClasses have provided extra training for potential elite athletes in Grades 7-9 in designated Danish public schools. They were introduced after the Danish Ministry of Culture lowered the age of recruitment for athletes from 15 to 12 in response to increased competition in the world of elite sports. The SportsClasses attempt to balance collaboration between two different organizations: Danish public schools and sports clubs. Using a survey of the student population in 2013 and a follow-up sample in 2015, we explore the respondents’ social backgrounds and experiences in order to understand their likelihood of retention during the program and their career aspirations. Focusing on socioeconomic status, the role of having parents in elite sports, gender, and type of sport, we study what key experiences and relationships lead students to abandon or sustain their interest in careers related to sports and how this differs for boys and girls. By applying Bourdieu’s concepts of habitus and types of capital, we conclude that the program produces elements of both reproduction and opportunity but that the patterns strongly favor the retention of boys compared to girls

The International Deep Planet Survey II: The frequency of directly imaged giant exoplanets with stellar mass

Radial velocity and transit methods are effective for the study of short orbital period exoplanets but they hardly probe objects at large separations for which direct imaging can be used. We carried out the international deep planet survey of 292 young nearby stars to search for giant exoplanets and determine their frequency. We developed a pipeline for a uniform processing of all the data that we have recorded with NIRC2/Keck II, NIRI/Gemini North, NICI/Gemini South, and NACO/VLT for 14 years. The pipeline first applies cosmetic corrections and then reduces the speckle intensity to enhance the contrast in the images. The main result of the international deep planet survey is the discovery of the HR 8799 exoplanets. We also detected 59 visual multiple systems including 16 new binary stars and 2 new triple stellar systems, as well as 2,279 point-like sources. We used Monte Carlo simulations and the Bayesian theorem to determine that 1.05[+2.80-0.70]% of stars harbor at least one giant planet between 0.5 and 14M_J and between 20 and 300 AU. This result is obtained assuming uniform distributions of planet masses and semi-major axes. If we consider power law distributions as measured for close-in planets instead, the derived frequency is 2.30[+5.95-1.55]%, recalling the strong impact of assumptions on Monte Carlo output distributions. We also find no evidence that the derived frequency depends on the mass of the hosting star, whereas it does for close-in planets. The international deep planet survey provides a database of confirmed background sources that may be useful for other exoplanet direct imaging surveys. It also puts new constraints on the number of stars with at least one giant planet reducing by a factor of two the frequencies derived by almost all previous works.Comment: 83 pages, 13 figures, 15 Tables, accepted in A&

Proteome analysis of the hyaluronic acid-producing bacterium, Streptococcus zooepidemicus

Background: Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is a commensal of horses and an opportunistic pathogen in many animals and humans. Some strains produce copious amounts of hyaluronic acid, making S. zooepidemicus an important industrial microorganism for the production of this valuable biopolymer used in the pharmaceutical and cosmetic industry. Encapsulation by hyaluronic acid is considered an important virulence factor in other streptococci, though the importance in S. zooepidemicus remains poorly understood. Proteomics may provide a better understanding of virulence factors in S. zooepidemicus, facilitate the design of better diagnostics and treatments, and guide engineering of superior production strains

High performance magnetocaloric perovskites for magnetic refrigeration

et al.We have applied mixed valance manganite perovskites as magnetocaloric materials in a magnetic refrigeration device. Relying on exact control of the composition and a technique to process the materials into single adjoined pieces, we have observed temperature spans above 9 K with two materials. Reasonable correspondence is found between experiments and a 2D numerical model, using the measured magnetocaloric properties of the two materials as input. © 2012 American Institute of Physics.The authors would like to acknowledge the support of the Programme Commission on Energy and Environment (EnMi) (Contract No. 2104-06-0032) which is part of the Danish Council for Strategic Research.Peer Reviewe

First-in-man mesenchymal stem cells for radiation-induced xerostomia (MESRIX):study protocol for a randomized controlled trial.

BACKGROUND: Salivary gland hypofunction and xerostomia are major complications following radiotherapy for head and neck cancer and may lead to debilitating oral disorders and impaired quality of life. Currently, only symptomatic treatment is available. However, mesenchymal stem cell (MSC) therapy has shown promising results in preclinical studies. Objectives are to assess safety and efficacy in a first-in-man trial on adipose-derived MSC therapy (ASC) for radiation-induced xerostomia. METHODS: This is a single-center, phase I/II, randomized, placebo-controlled, double-blinded clinical trial. A total of 30 patients are randomized in a 1:1 ratio to receive ultrasound-guided, administered ASC or placebo to the submandibular glands. The primary outcome is change in unstimulated whole salivary flow rate. The secondary outcomes are safety, efficacy, change in quality of life, qualitative and quantitative measurements of saliva, as well as submandibular gland size, vascularization, fibrosis, and secretory tissue evaluation based on contrast-induced magnetic resonance imaging (MRI) and core-needle samples. The assessments are performed at baseline (1 month prior to treatment) and 1 and 4 months following investigational intervention. DISCUSSION: The trial is the first attempt to evaluate the safety and efficacy of adipose-derived MSCs (ASCs) in patients with radiation-induced xerostomia. The results may provide evidence for the effectiveness of ASC in patients with salivary gland hypofunction and xerostomia and deliver valuable information for the design of subsequent trials. TRIAL REGISTRATION: EudraCT, Identifier: 2014-004349-29. Registered on 1 April 2015. ClinicalTrials.gov, Identifier: NCT02513238. First received on 2 July 2015. The trial is prospectively registered. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13063-017-1856-0) contains supplementary material, which is available to authorized users