1,661 research outputs found
Scaling laws for the decay of multiqubit entanglement
We investigate the decay of entanglement of generalized N-particle
Greenberger-Horne-Zeilinger (GHZ) states interacting with independent
reservoirs. Scaling laws for the decay of entanglement and for its finite-time
extinction (sudden death) are derived for different types of reservoirs. The
latter is found to increase with the number of particles. However, entanglement
becomes arbitrarily small, and therefore useless as a resource, much before it
completely disappears, around a time which is inversely proportional to the
number of particles. We also show that the decay of multi-particle GHZ states
can generate bound entangled states.Comment: Minor mistakes correcte
No relationship between lean mass and functional asymmetry in high-level female tennis players
The relationship between lean mass and functional asymmetry in terms of their magnitude and direction was examined in 22 high-level female tennis players (20.9 ± 3.6 years). Lean mass of both upper and lower extremities was examined using Dual X-ray Absorptiometry. Functional asymmetry was assessed using a battery of field tests (handgrip strength, seated shot-put throw, plate tapping, single leg countermovement jump, single leg forward hop test, 6 m single leg hop test, and 505 change of direction (time and deficit)). Paired sample t-tests compared the dominant (overall highest/best (performance) value) against the non-dominant value (highest/best (performance) value of the opposing extremity). Linear regressions were used to explore the relationship between lean mass and functional asymmetry magnitudes. Kappa coefficients were used to examine the consistency in direction between the extremity displaying the highest lean mass value and the extremity performing dominantly across tests. Significant asymmetry magnitudes (p 0.05) were found for all upper and lower extremity lean mass and functional values. No relationship was apparent between lean mass and functional asymmetry magnitudes (p-value range = 0.131–0.889). Despite finding perfect consistency in asymmetry direction (k-value = 1.00) for the upper extremity, poor to fair consistency (k-value range = −0.00–0.21) was found for the lower extremity. In conclusion, lean mass and functional asymmetries should be examined independently
Robustness of Entanglement as a Resource
The robustness of multipartite entanglement of systems undergoing decoherence
is of central importance to the area of quantum information. Its
characterization depends however on the measure used to quantify entanglement
and on how one partitions the system. Here we show that the unambiguous
assessment of the robustness of multipartite entanglement is obtained by
considering the loss of functionality in terms of two communication tasks,
namely the splitting of information between many parties and the teleportation
of states.Comment: 11 pages, 5 figure
Primera cita del Entoprocto Pedicellina hispida Ryland, 1965 en el mar Mediterráneo (costa tunecina)
Not available.No disponibl
Mesoporous aluminosilicate nanofibers with a low Si/Al ratio as acidic catalyst for hydrodeoxygenation of phenol
Mesoporous aluminosilicate nanofibers (mASNF) were prepared using hard and soft dual templates approach. The mesoporous material was fully characterized and its acidic nature was confirmed by FTIR spectroscopy of pyridine adsorption and 27Al/29Si solid state NMR. Thanks to the incorporated aluminum atoms, the acidic material showed high hydrothermal stability which is an essential property for biomass conversion applications. The catalytic performance of Pd supported on mASNF for hydrodeoxygenation (HDO) of lignin model compound was also investigated. A complete conversion and a high selectivity towards cyclohexane (up to 95%) starting from phenol were achieved with this bifunctional catalyst. In comparison, no cyclohexane has been produced with a non-acidic material which underlines the importance of acidic sites in HDO process selectivity control. Moreover, the catalyst can be recycled without losing its initial structure
Face and content validity of the pictorial scale of perceived water competence in young children
An international group of experts have developed a pictorial tool to measure perceived water competence for children aged from 5 to 8 years old: the Pictorial Scale of Perceived Water Competence (PSPWC). The aim of the present study was to verify the validity of this tool. In the first part of the study, 120 children were interviewed to investigate face validity of the PSPWC to ensure that all pictorial items were understandable. In the second part of the study, 13 scientific and/or pedagogical international experts were invited to assess the tool's content validity via an online survey. Face validity results revealed that children were able to understand and sequence correctly the aquatic situations in 92% of the cases. The average Content Validity Index (CVI) of the PSPWC ranged from 0.88 to 0.95, showing acceptable content validity. Feedback from experts and children resulted in a major improvement of the "exit water" situation and minor improvements concerning some other items. Experts confirmed that the PSPWC was globally appropriate for different countries and cultures, except for the situation "water entry by slide" which was not considered usual practice in some countries. The PSPWC opens up to new fields of research; useful both for the prevention of drowning and for the support of children's aquatic education
Assisting walking balance using a bio-inspired exoskeleton controller
Background: Balance control is important for mobility, yet exoskeleton research has mainly focused on improving metabolic energy efficiency. Here we present a biomimetic exoskeleton controller that supports walking balance and reduces muscle activity. Methods: Humans restore balance after a perturbation by adjusting activity of the muscles actuating the ankle in proportion to deviations from steady-state center of mass kinematics. We designed a controller that mimics the neural control of steady-state walking and the balance recovery responses to perturbations. This controller uses both feedback from ankle kinematics in accordance with an existing model and feedback from the center of mass velocity. Control parameters were estimated by fitting the experimental relation between kinematics and ankle moments observed in humans that were walking while being perturbed by push and pull perturbations. This identified model was implemented on a bilateral ankle exoskeleton. Results: Across twelve subjects, exoskeleton support reduced calf muscle activity in steady-state walking by 19% with respect to a minimal impedance controller (p < 0.001). Proportional feedback of the center of mass velocity improved balance support after perturbation. Muscle activity is reduced in response to push and pull perturbations by 10% (p = 0.006) and 16% (p < 0.001) and center of mass deviations by 9% (p = 0.026) and 18% (p = 0.002) with respect to the same controller without center of mass feedback. Conclusion: Our control approach implemented on bilateral ankle exoskeletons can thus effectively support steady-state walking and balance control and therefore has the potential to improve mobility in balance-impaired individuals.Support Biomechanical Engineerin
Minimal Influence of Extracellular DNA on Molecular Surveys of Marine Sedimentary Communities
Extracellular DNA has been reported to comprise a large fraction of total DNA in near-seafloor sediment. However, the potential effect of extracellular DNA, arising from dead or moribund cells, on sequencing surveys is a critical concern that has largely not been addressed for marine sedimentary habitats. To address this concern, we interrogated freshly collected Arctic and Pacific sediment for extracellular 16S rRNA genes using the photoactive DNA-binding dye Propidium Monoazide. Significant differences between relative abundances of total (intracellular + extracellular) Bacterial 16S rRNA genes and relative abundances of intracellular Bacterial 16S rRNA genes are only detected in three of twelve shallow [10 cm below seafloor (cmbsf)] samples. Relative abundances of total Bacterial 16S rRNA genes are statistically indistinguishable from relative abundances of intracellular Bacterial 16S rRNA genes in all interrogated samples from depths greater than 10 cmbsf. 16S rRNA gene sequencing shows that even where significantly higher abundances of extracellular genes are detected, they have little or no influence on prokaryote community composition. Taxon-level analyses suggest that extracellular DNA, arising from in situ death, may be sourced from different organisms in sediment of different ages. However, the overall effect of extracellular genes on sequencing surveys of marine sedimentary prokaryotes is minimal
Ogre and Pythia: An Invariance Proof Method for Weak Consistency Models
We design an invariance proof method for concurrent programs parameterised by a weak consistency model. The calculational design of the invariance proof method is by abstract interpretation of a truly parallel analytic semantics. This generalises the methods by Lamport and Owicki-Gries for sequential consistency. We use cat as an example of language to write consistency specifications of both concurrent programs and machine architectures
- …