Experimental Evaluation of Seed Limitation in Alpine Snowbed Plants

Background: The distribution and abundance of plants is controlled by the availability of seeds and of sites suitable for establishment. The relative importance of these two constraints is still contentious and possibly varies among species and ecosystems. In alpine landscapes, the role of seed limitation has traditionally been neglected, and the role of abiotic gradients emphasized. Methodology/Principal Findings: We evaluated the importance of seed limitation for the incidence of four alpine snowbed species (Achillea atrata L., Achillea clusiana Tausch, Arabis caerulea L., Gnaphalium hoppeanum W. D. J. Koch) in local plant communities by comparing seedling emergence, seedling, juvenile and adult survival, juvenile and adult growth, flowering frequency as well as population growth rates lambda of experimental plants transplanted into snowbed patches which were either occupied or unoccupied by the focal species. In addition, we accounted for possible effects of competition or facilitation on these rates by including a measure of neighbourhood biomass into the analysis. We found that only A. caerulea had significantly lower seedling and adult survival as well as a lower population growth rate in unoccupied sites whereas the vital rates of the other three species did not differ among occupied and unoccupied sites. By contrast, all species were sensitive to competitive effects of the surrounding vegetation in terms of at least one of the studied rates. Conclusions/Significance: We conclude that seed and site limitation jointly determine the species composition of these snowbed plant communities and that constraining site factors include both abiotic conditions and biotic interactions. The traditional focus on abiotic gradients for explaining alpine plant distribution hence appears lopsided. The influence of seed limitation on the current distribution of these plants casts doubt on their ability to readily track shifting habitats under climate change unless seed production is considerably enhanced under a warmer climate

EOS ® orthopaedic imaging system to study patellofemoral kinematics : Assessment of uncertainty

The author extends his thanks to Dr. A. Asselineau, Pr David Mitton, Mr. Sébastien Laporte and Mr. Benjamin Aubert for their assistance.Background:Accurate knowledge of knee joint kinematics, especially patellofemoral joint kinematics, is essential for prosthetic evaluation so as to further improve total knee arthroplasty performances. Improving the evaluation of the functioning of the extensor apparatus appears, in this respect, particularly important in this optimization effort. Objectives:The aim of this study was to propose a new experimental setup for the analysis of knee joint kinematics and to validate its relevance in terms of accuracy and uncertainty. The technique developed herein combines 3D reconstruction imaging with the use of a motion capture system. Material and methods: Eight pairs of fresh-frozen cadaver specimens with no evidence of previous knee surgery were studied using a new test rig where the femur remains fixed and the tibia is free to rotate. The flexion—extension cycles were executed using computer-controlled traction of the quadriceps tendon combined with an antagonist force applied to the distal part of the tibia. Knee joint kinematics were tracked using an optoelectronic motion capture system after a preliminary stage of data acquisition of bone geometry and markers position. This stage was carried out using a new digital stereophotogrammetric system, EOS® , combined with specific 3D reconstruction software that also determined the coordinate system used in the kinematic analysis. The resulting uncertainty was assessed as was its impact on the estimated kinematics. Results:Test results on eight knees validated the setup designed for the analysis of knee joint kinematics during the flexion—extension cycle. More specifically, the statistical results show that measurement uncertainty for rotations and translations remains below 0.4 and 1.8 mm, respectively, for the tibia and 0.4 and 1.2 mm for the patella (±2 S.D. for all four measurements)

Observations on the Luzon Water redstart Rhyacornis bicolor in the Mount Pulog National Park, Philippines

Volume: 7Start Page: 147End Page: 15

Geometric and Computational Approach to Classical and Quantum Secret Sharing

Producción CientíficaLinear ramp secret sharing schemes are given by a pair of nested codes. In this work algebraic geometry codes are considered. We found sufficient conditions for qualified or forbidden sets by using geometric properties of the set of points. This article considers both classical schemes and quantum schemes.The authors gratefully acknowledge the support from Japan Society for the Promotion of Science (Grant Nos. 23246071 and 26289116), from the Spanish MINECO (Grant No. MTM2012-36917-C03-03), the Danish Council for Independent Research (Grant No. DFF-4002-00367) and from the "Program for Promoting the Enhancement of Research Universities'' at Tokyo Institute of Technology