228 research outputs found
BPS Vortices in Non-relativistic M2-brane Chern-Simons-matter Theory
We study BPS vortices in the mass-deformed non-relativistic {\C N}=6
Chern-Simons-matter theory. We focus on the massive
deformation that preserves the maximal {\C N}=6 supersymmetry, and consider a
non-relativistic limit that carry 14 supercharges. In this non-relativistic
field theory we find Jackiw-Pi type exact vortex solutions combined with
fuzzy sphere geometry. We analyse their properties and show that they preserve
one dynamical, one conformal and five kinematical supersymmetries among the
full super Schr\"odinger symmetry.Comment: 22 pages, 3 figures, typos corrected, reference adde
Motion of the Tippe Top : Gyroscopic Balance Condition and Stability
We reexamine a very classical problem, the spinning behavior of the tippe top
on a horizontal table. The analysis is made for an eccentric sphere version of
the tippe top, assuming a modified Coulomb law for the sliding friction, which
is a continuous function of the slip velocity at the point of
contact and vanishes at . We study the relevance of the gyroscopic
balance condition (GBC), which was discovered to hold for a rapidly spinning
hard-boiled egg by Moffatt and Shimomura, to the inversion phenomenon of the
tippe top. We introduce a variable so that corresponds to the GBC
and analyze the behavior of . Contrary to the case of the spinning egg,
the GBC for the tippe top is not fulfilled initially. But we find from
simulation that for those tippe tops which will turn over, the GBC will soon be
satisfied approximately. It is shown that the GBC and the geometry lead to the
classification of tippe tops into three groups: The tippe tops of Group I never
flip over however large a spin they are given. Those of Group II show a
complete inversion and the tippe tops of Group III tend to turn over up to a
certain inclination angle such that , when they are
spun sufficiently rapidly. There exist three steady states for the spinning
motion of the tippe top. Giving a new criterion for stability, we examine the
stability of these states in terms of the initial spin velocity . And we
obtain a critical value of the initial spin which is required for the
tippe top of Group II to flip over up to the completely inverted position.Comment: 52 pages, 11 figures, to be published in SIAM Journal on Applied
Dynamical Syste
Time Discounting: The Delay Effect and Procrastinating Behavior
The delay effect, that people discount the near future more than the distant future, has not been verified rigorously. An experiment conducted by us in China confirms that, by separating the delay from the interval, the delay effect exists only within a short delay. The results are reliable, because the rewards paid were very large, in order to elicit the subjects' true preferences. The interval and magnitude effects are also confirmed. Finally, subjects' procrastinating behavior, as reported in the questionnaire conducted at the end of the experiment, is explained by the time discount rates and the degree of the delay effect revealed in the experiment.
Tapping but Not Massage Enhances Vasodilation and Improves Venous Palpation of Cutaneous Veins
This paper investigated whether tapping on the median cubital vein or massaging the forearm was more effective in obtaining better venous palpation for venipuncture. Forty healthy volunteers in their twenties were subjected to tapping (10 times in 5 sec) or massage (10 strokes in 20 sec from the wrist to the cubital fossa) under tourniquet inflation on the upper arm. Venous palpation was assessed using the venous palpation score (0-6, with 0 being impalpable). Three venous factorsâvenous depth, cross-sectional area, and elevationâwere also measured using ultrasonography. The venous palpation score increased significantly by tapping but not by massage. Moreover, all 3 venous measurements changed significantly by tapping, while only the depth decreased significantly by massage. The three venous measurements correlated significantly with the venous palpation score, indicating that they are useful objective indicators for evaluating vasodilation. We suggest that tapping is an effective vasodilation technique
Relationship between Tourniquet Pressure and a Cross-Section Area of Superficial Vein of Forearm
This study investigated the appropriate tourniquet pressure (TP) and duration of tourniquet application for venipuncture by calculating the venous cross-section (VCS) area on ultrasonography. Twenty healthy volunteers without cardiovascular risk factors were enrolled in this study. A target vein (either a cephalic or median cubital vein) was selected on ultrasonography. The pneumatic tourniquet was inflated using a rapid cuff inflator system at setting pressure for 120sec. TP strength was varied from 20mmHg to 100mmHg, in 20mmHg increments. The order of TP was randomized. Compari-sons among more than 3 groups were performed by one-way repeated-measures ANOVA and the Bonferroni method. The VCS area increased rapidly until 10sec after tourniquet inflation. The VCS area then increased gradually until 30sec after tourniquet inflation. After that, the VCS area did not increase remarkably. The VCS area increased with TP strength up to 80mmHg, but the VCS area at TP 100mmHg decreased to less than that at TP 40mmHg. Based on these results, we recommend a tourniquet pressure of 60mmHg, and duration of tourniquet application is 30 to 60sec for venipuncture
Simultaneous Imaging and Characterization of Polyunsaturated Fatty Acids, Carotenoids, and Microcrystalline Guanine in Single Aurantiochytrium limacinum Cells with Linear and Nonlinear Raman Microspectroscopy
Thraustochytrids are heterotrophic marine protists known for their high production capacity of various compounds with health benefits, such as polyunsaturated fatty acids and carotenoids. Although much effort has been focused on developing optimal cultivation methods for efficient microbial production, these high-value compounds and their interrelationships are not well understood at the single-cell level. Here we used spontaneous (linear) Raman and multiplex coherent anti-Stokes Raman scattering (CARS) micro-spectroscopy to visualize and characterize lipids (e.g., docosahexaenoic acid) and carotenoids (e.g., astaxanthin) accumulated in single living Aurantiochytrium limacinum cells. Spontaneous Raman imaging with the help of multivariate curve resolutionâalternating least-squares enabled us to make unambiguous assignments of the molecular components we detected and derive their intracellular distributions separately. Near-IR excited CARS imaging yielded the Raman images at least an order of magnitude faster than spontaneous Raman imaging, with suppressed contributions of carotenoids. As the culture time increased from 2 to 5 days, the lipid amount increased by a factor of âŒ7, whereas the carotenoid amount did not change significantly. Furthermore, we observed a highly localized component in A. limacinum cells. This component was found to be mixed crystals of guanine and other purine derivatives. The present study demonstrates the potential of the linearânonlinear Raman hybrid approach that allows for accurate molecular identification and fast imaging in a label-free manner to link information derived from single cells with strategies for mass culture of useful thraustochytrids
Location-Specific Cortical Activation Changes during Sleep after Training for Perceptual Learning
Visual perceptual learning is defined as performance enhancement on a sensory task and is distinguished from
other types of learning and memory in that it is highly specific for location of the trained stimulus. The location specificity has been shown to be paralleled by enhancement in functional magnetic resonance imaging (fMRI) signal in the trained region of V1 after visual training. Although recently the role of sleep in strengthening visual perceptual learning has attracted much attention, its underlying neural mechanism has yet to be clarified. Here, for the first time, fMRI measurement of human V1 activation was conducted concurrently with a polysomnogram during sleep with and without preceding training for visual perceptual learning. As a result of predetermined region-of-interest analysis of V1, activation enhancement during non-rapid-eye-movement
sleep after training was observed specifically in the trained region of V1. Furthermore, improvement of task
performance measured subsequently to the post-training sleep session was significantly correlated with the amount
of the trained-region-specific fMRI activation in V1 during sleep. These results suggest that as far as V1 is concerned, only the trained region is involved in improving task performance after sleep
Analyses of integrated EPID images for on-treatment quality assurance to account for interfractional variations in volumetric modulated arc therapy
Purpose: To investigate the effects of interfractional variation, such as anatomical changes and setup errors, on dose delivery during treatment for prostate cancer (PC) and head and neck cancer (HNC) by courses of volumetric modulated arc therapy (VMAT) aided by onâtreatment electronic portal imaging device (EPID) images. Methods: Seven patients with PC and 20 patients with HNC who had received VMAT participated in this study. After obtaining photon fluence at the position of the EPID for each treatment arc from onâtreatment integrated EPID images, we calculated the differences between the fluence for the first fraction and each subsequent fraction for each arc. The passing rates were investigated based on a tolerance level of 3% of the maximum fluence during the treatment courses and the correlations between the passing rates and anatomical changes. Results: In PC, the median and lowest passing rates were 99.8% and 95.2%, respectively. No correlations between passing rates and interfractional variation were found. In HNC, the median passing rate of all fractions was 93.0%, and the lowest passing rate was 79.6% during the 35th fraction. Spearmanâs correlation coefficients between the passing rates and changes in weight or neck volume were â 0.77 and â 0.74, respectively. Conclusions: Analyses of the onâtreatment EPID images facilitates estimates of the interfractional anatomical variation in HNC patients during VMAT and thus improves assessments of the need for reâplanning or adaptive strategies and the timing thereof
- âŠ