427 research outputs found

    Fe, Zn, Mn and N transfer between size classes in a coastal phytoplankton community: Trace metal and major nutrient recycling compared

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    Experiments were performed to investigate transfer of 59Fe, 65Zn, 54Mn, and 15N from labeled cyanobacteria to the large (\u3e8 μm or \u3e5 μm) phytoplankton size class from Monterey Bay, California. Transfer of metal isotope activity was measured from and into total (for all isotopes) and intracellular (59Fe only) pools. Results demonstrated rapid and efficient transfer of nitrogen to the large phytoplankton size class; intracellular 59Fe was transferred into the intracellular and total pools of the \u3e8 μm phytoplankton size class 70% and 130% as efficiently as nitrogen, respectively. 65Zn and 54Mn were transferred between size classes 48% and 23% as efficiently as N. Extracellular 59Fe and 65Zn from the added cyanobacteria also appeared quickly in the large size fraction, although most of the Fe transfer appeared to be the result of surface adsorption rather than biological uptake. These data are discussed in relation to the biological recycling efficiencies of the four elements and the resulting implications for biogeochemical cycling of trace and major nutrient elements

    170 Nanometer Nuclear Magnetic Resonance Imaging using Magnetic Resonance Force Microscopy

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    We demonstrate one-dimensional nuclear magnetic resonance imaging of the semiconductor GaAs with 170 nanometer slice separation and resolve two regions of reduced nuclear spin polarization density separated by only 500 nanometers. This is achieved by force detection of the magnetic resonance, Magnetic Resonance Force Microscopy (MRFM), in combination with optical pumping to increase the nuclear spin polarization. Optical pumping of the GaAs creates spin polarization up to 12 times larger than the thermal nuclear spin polarization at 5 K and 4 T. The experiment is sensitive to sample volumes containing 4×1011\sim 4 \times 10^{11} 71^{71}Ga/Hz/\sqrt{Hz}. These results demonstrate the ability of force-detected magnetic resonance to apply magnetic resonance imaging to semiconductor devices and other nanostructures.Comment: Submitted to J of Magnetic Resonanc

    Converging Technologies - Shaping the Future of European Societies

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    The European Commission and Member States are called upon to recognise the novel potential of Converging Technologies (CTs) to advance the Lisbon Agenda. Wise investment in CTs stimulates science and technology research, strengthens economic competitiveness, and addresses the needs of European societies and their citizens. Preparatory action should be taken to implement CT as a thematic research priority, to develop Converging Technologies for the European Knowledge Society (CTEKS) as a specifically European approach to CTs, and to establish a CTEKS research communit

    A modeling assessment of the role of reversible scavenging in controlling oceanic dissolved Cu and Zn distributions

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    The balance of processes that control elemental distributions in the modern oceans is important in understanding both their internal recycling and the rate and nature of their eventual output to sediment. Here we seek to evaluate the likely controls on the vertical profiles of Cu and Zn. Though the concentrations of both Cu and Zn increase with depth, Cu increases in a more linear fashion than Zn, which exhibits a typical "nutrient-type" profile. Both elements are bioessential, and biological uptake and regeneration has often been cited as an important process in controlling their vertical distribution. In this study, we investigate the likely importance of another key vertical process, that of passive scavenging on sinking particles, via a simple one-dimensional model of reversible scavenging. We find that, despite the absence of lateral or vertical water advection, mixing, diffusion, or biological uptake, our reversible scavenging model is very successful in replicating dissolved Cu concentration profiles on a range of geographic scales. We provide preliminary constraints on the scavenging coefficients for Cu for a spectrum of particle types (calcium carbonate, opal, particulate organic carbon, and dust) while emphasizing the fit of the shape of the modeled profile to that of the tracer data. In contrast to Cu, and reaffirming the belief that Zn behaves as a true micronutrient, the scavenging model is a poor match to the shape of oceanic Zn profiles. Modeling a single vertical process simultaneously highlights the importance of lateral advection in generating high Zn concentrations in the deep Pacific. Key Points A 1-D reversible scavenging model is applied to oceanic [Cu] and [Zn]Dissolved Cu is well described by the process of reversible scavengingDissolved Zn is not, reflecting its behaviour as a true nutrient-type element ©2013. American Geophysical Union. All Rights Reserved

    Deceptive body movements reverse spatial cueing in soccer

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    This article has been made available through the Brunel Open Access Publishing Fund.The purpose of the experiments was to analyse the spatial cueing effects of the movements of soccer players executing normal and deceptive (step-over) turns with the ball. Stimuli comprised normal resolution or point-light video clips of soccer players dribbling a football towards the observer then turning right or left with the ball. Clips were curtailed before or on the turn (-160, -80, 0 or +80 ms) to examine the time course of direction prediction and spatial cueing effects. Participants were divided into higher-skilled (HS) and lower-skilled (LS) groups according to soccer experience. In experiment 1, accuracy on full video clips was higher than on point-light but results followed the same overall pattern. Both HS and LS groups correctly identified direction on normal moves at all occlusion levels. For deceptive moves, LS participants were significantly worse than chance and HS participants were somewhat more accurate but nevertheless substantially impaired. In experiment 2, point-light clips were used to cue a lateral target. HS and LS groups showed faster reaction times to targets that were congruent with the direction of normal turns, and to targets incongruent with the direction of deceptive turns. The reversed cueing by deceptive moves coincided with earlier kinematic events than cueing by normal moves. It is concluded that the body kinematics of soccer players generate spatial cueing effects when viewed from an opponent's perspective. This could create a reaction time advantage when anticipating the direction of a normal move. A deceptive move is designed to turn this cueing advantage into a disadvantage. Acting on the basis of advance information, the presence of deceptive moves primes responses in the wrong direction, which may be only partly mitigated by delaying a response until veridical cues emerge

    Dynamical fidelity of a solid-state quantum computation

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    In this paper we analyze the dynamics in a spin-model of quantum computer. Main attention is paid to the dynamical fidelity (associated with dynamical errors) of an algorithm that allows to create an entangled state for remote qubits. We show that in the regime of selective resonant excitations of qubits there is no any danger of quantum chaos. Moreover, in this regime a modified perturbation theory gives an adequate description of the dynamics of the system. Our approach allows to explicitly describe all peculiarities of the evolution of the system under time-dependent pulses corresponding to a quantum protocol. Specifically, we analyze, both analytically and numerically, how the fidelity decreases in dependence on the model parameters.Comment: 9 pages, 6 figures, submitted to PR

    An off-board quantum point contact as a sensitive detector of cantilever motion

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    Recent advances in the fabrication of microelectromechanical systems (MEMS) and their evolution into nanoelectromechanical systems (NEMS) have allowed researchers to measure extremely small forces, masses, and displacements. In particular, researchers have developed position transducers with resolution approaching the uncertainty limit set by quantum mechanics. The achievement of such resolution has implications not only for the detection of quantum behavior in mechanical systems, but also for a variety of other precision experiments including the bounding of deviations from Newtonian gravity at short distances and the measurement of single spins. Here we demonstrate the use of a quantum point contact (QPC) as a sensitive displacement detector capable of sensing the low-temperature thermal motion of a nearby micromechanical cantilever. Advantages of this approach include versatility due to its off-board design, compatibility with nanoscale oscillators, and, with further development, the potential to achieve quantum limited displacement detection.Comment: 5 pages, 5 figure

    Kissing right? On the consistency of the head-turning bias in kissing

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    The present study investigated the consistency of the head-turning bias in kissing. In particular we addressed what happens if a person who prefers to kiss with the head turned to the right kisses a person who prefers to kiss with the head turned to the left. To this end, participants (N=57) were required to kiss a life-sized doll's head rotated in different orientations that were either compatible or incompatible with the participants' head-turning preference. Additionally, participants handedness, footedness, and eye preference was assessed. Results showed that a higher percentage of participants preferred to kiss with their head turned to the right than to the left. In addition, the right-turners were more consistent in their kissing behaviour than left-turners. That is, with the doll's head rotated in an incompatible direction, right-turners were less likely to switch their head to their non-preferred side. Since no clear relationships between head-turning bias and the other lateral preferences (i.e., handedness, footedness, and eye preference) were discerned, the more consistent head-turning bias among right-turners could not be explained as deriving from a joint pattern of lateral preferences that is stronger among individuals with rightward as compared to individuals with leftward lateral preferences. © 2010 Psychology Press

    Efficacy and Safety of Radium-223 Dichloride in Symptomatic Castration-resistant Prostate Cancer Patients With or Without Baseline Opioid Use From the Phase 3 ALSYMPCA Trial

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    Background: The phase 3 ALSYMPCA trial enrolled metastatic castration-resistant prostate cancer patients with or without baseline opioid use. Objective: To assess the efficacy and safety of radium-223 dichloride (radium-223) versus placebo in ALSYMPCA patients by baseline opioid use. Design, setting, and participants: Nine hundred and twenty one patients enrolled at 136 centers globally. Intervention: Radium-223 (50 kBq/kg, intravenous injection) every 4 wk for six cycles or matching placebo, each plus best standard of care. Outcome measurements and statistical analysis: Primary endpoint (overall survival [OS]), main secondary efficacy endpoints, and safety were evaluated by baseline opioid use. Additional analyses included time to first opioid use, time to first external beam radiation therapy for bone pain, and safety of concomitant external beam radiation therapy. Results and limitations: At baseline, 408 (44%) patients had no pain and no analgesic use or mild pain with nonopioid therapy (World Health Organization ladder pain score 0–1 [nonopioid subgroup]), and 513 (56%) had moderate pain with occasional opioids or severe pain with regular daily opioids (World Health Organization ladder pain score 2–3 [opioid subgroup]). Radium-223 significantly prolonged OS versus placebo in nonopioid (hazard ratio [HR] = 0.70; 95% confidence interval [CI]: 0.52–0.93; p = 0.013) and opioid (HR = 0.68; 95% CI: 0.54–0.86; p = 0.001) subgroups, and significantly reduced risk of symptomatic skeletal events versus placebo, regardless of baseline opioid use (nonopioid subgroup: HR = 0.56, 95% CI: 0.39– 0.82, p = 0.002; opioid subgroup: HR = 0.72, 95% CI: 0.53–0.98, p = 0.038). Time to first opioid use for bone pain was significantly delayed with radium-223 versus placebo (HR = 0.62, 95% CI: 0.46–0.85, p = 0.002). Adverse event incidences were similar between opioid subgroups. Conclusions: Radium-223 versus placebo significantly prolonged OS and reduced symptomatic skeletal event risk with a favorable safety profile in castration-resistant prostate cancer patients with symptomatic bone metastases, regardless of baseline opioid use. Patient summary: In this ALSYMPCA opioid subgroup analysis, baseline symptom levels did not appear to impact radium-223 dichloride efficacy or safet

    Identifying the mechanisms underpinning recognition of structured sequences of action

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    © 2012 The Experimental Psychology SocietyWe present three experiments to identify the specific information sources that skilled participants use to make recognition judgements when presented with dynamic, structured stimuli. A group of less skilled participants acted as controls. In all experiments, participants were presented with filmed stimuli containing structured action sequences. In a subsequent recognition phase, participants were presented with new and previously seen stimuli and were required to make judgements as to whether or not each sequence had been presented earlier (or were edited versions of earlier sequences). In Experiment 1, skilled participants demonstrated superior sensitivity in recognition when viewing dynamic clips compared with static images and clips where the frames were presented in a nonsequential, randomized manner, implicating the importance of motion information when identifying familiar or unfamiliar sequences. In Experiment 2, we presented normal and mirror-reversed sequences in order to distort access to absolute motion information. Skilled participants demonstrated superior recognition sensitivity, but no significant differences were observed across viewing conditions, leading to the suggestion that skilled participants are more likely to extract relative rather than absolute motion when making such judgements. In Experiment 3, we manipulated relative motion information by occluding several display features for the duration of each film sequence. A significant decrement in performance was reported when centrally located features were occluded compared to those located in more peripheral positions. Findings indicate that skilled participants are particularly sensitive to relative motion information when attempting to identify familiarity in dynamic, visual displays involving interaction between numerous features
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