Structure constants of operators on the Wilson loop from integrability

We study structure constants of local operators inserted on the Wilson loop in ${\cal N}=4$ super Yang-Mills theory. We compute the structure constants in the SU(2) sector at tree level using the correspondence between operators on the Wilson loop and the open spin chain. The results are interpreted as the summation over all possible ways of changing the signs of magnon momenta in the hexagon form factors. This is consistent with a holographic description of the correlator as the cubic open string vertex, which consists of one hexagonal patch and three boundaries. We then conjecture that a similar expression should hold also at finite coupling.Comment: 38 pages; v3: JHEP published versio

Structure Constants of Defect Changing Operators on the 1/2 BPS Wilson Loop

We study three-point functions of operators on the $1/2$ BPS Wilson loop in planar $\mathcal{N}=4$ super Yang-Mills theory. The operators we consider are "defect changing operators", which change the scalar coupled to the Wilson loop. We first perform the computation at two loops in general set-ups, and then study a special scaling limit called the ladders limit, in which the spectrum is known to be described by a quantum mechanics with the SL(2,$\mathbb{R}$) symmetry. In this limit, we resum the Feynman diagrams using the Schwinger-Dyson equation and determine the structure constants at all order in the rescaled coupling constant. Besides providing an interesting solvable example of defect conformal field theories, our result gives invaluable data for the integrability-based approach to the structure constants.Comment: 31 pages + appendices; v2 References adde

Mermaid construction in Kathmandu Newar

The University of Mimasak

Negation patterns in Meche

This paper discusses the negation structure of Meche, a Tibeto-Burman language spoken in the southeastern part of Nepal. The negation marker in Meche is not cognate with the Proto-Tibeto-Burman negation prefix *ma-, but is suffixal, as observed in other TB languages of North East India. The Meche negation suffixes are not simple negation markers attached to the verb in affirmative clauses, but rather constitute a paradigm contrasting with affirmative suffixes with respect to tense-aspect-modality (habitual -ə vs. -a, future -nai vs. -a, past -ɑʔ vs. -yi, recent past/perfect -bai vs. -akəi, continuous/perfect -dəŋ vs. -akəi). In negative clauses, negation suffixes occur instead of corresponding affirmative verbal suffixes. There is, however, one negative prefix: the prohibitive marker da-, which is cognate with the PTB-negative imperative marker *da/ta. Meche has a negation suffix that signals a change of situation into a negative state, -le. The negation in subordinate clauses is based on finite negation markers, but the patterns are slightly different. The nominalized clause is formed by one of the two nominalizers, -gra and -nai, for affirmative nominalized clauses. However, there is only one negative nominalizer -yi. For temporal- conditional adverbial clauses, the finite negative suffixes are used, while for other types of adverbial clauses, which are based on nominalization, the negative nominalizer -yi is always used. Finally, the paper speculates regarding a possible origin of one of the negative suffixes in Meche based on Wood (2008) and a piece of data from Tani (Post 2015). The negative suffix -a might have originated from the Proto-Bodo-Garo prohibitive *ta, which is cognate with PTB *da/ta, and which for some reason might have been employed as a regular negative marker. A possible phonological change would be ta > ca > ja > ya > a in Boro and Meche

Vibration of Tensegrity Stucture by using SEM

A tensegrity structure is a structure which consists both of compressive and tensile elements without being restrained at the boundaries. The self-equilibrium state inside the tensegrity structure is the condition that builds the structure without any boundary condition necessity. The conventional Eigensystem solver cannot deal with this kind of structure since there are rigid body motions in the governing equations. The exact dynamic solution of tensegrity structure problems can only be obtained by using the frequency-dependent dynamic method. In this study, the free vibrational characteristics of a tensegrity structure which is modeled by a combination of the compressive strut and tensile cables elements are solved by using the Spectral Element Method (SEM). Natural frequencies of the tensegrity are tracked by using the Wittrick-Williams algorithm. Numerical calculations are given to show the effectiveness, efficiency, and accuracy of the SEM in solving the axially vibrating members of the tensegrity structures

Relationships between sensory stimuli and autonomic nervous regulation during real and virtual exercises

<p>Abstract</p> <p>Background</p> <p>Application of virtual environment (VE) technology to motor rehabilitation increases the number of possible rehabilitation tasks and/or exercises. However, enhancing a specific sensory stimulus sometimes causes unpleasant sensations or fatigue, which would in turn decrease motivation for continuous rehabilitation. To select appropriate tasks and/or exercises for individuals, evaluation of physical activity during recovery is necessary, particularly the changes in the relationship between autonomic nervous activity (ANA) and sensory stimuli.</p> <p>Methods</p> <p>We estimated the ANA from the R-R interval time series of electrocardiogram and incoming sensory stimuli that would activate the ANA. For experiments in real exercise, we measured vehicle data and electromyogram signals during cycling exercise. For experiments in virtual exercise, we measured eye movement in relation to image motion vectors while the subject was viewing a mountain-bike video image from a first-person viewpoint.</p> <p>Results</p> <p>For the real cycling exercise, the results were categorized into four groups by evaluating muscle fatigue in relation to the ANA. They suggested that fatigue should be evaluated on the basis of not only muscle activity but also autonomic nervous regulation after exercise. For the virtual exercise, the ANA-related conditions revealed a remarkable time distribution of trigger points that would change eye movement and evoke unpleasant sensations.</p> <p>Conclusion</p> <p>For expanding the options of motor rehabilitation using VE technology, approaches need to be developed for simultaneously monitoring and separately evaluating the activation of autonomic nervous regulation in relation to neuromuscular and sensory systems with different time scales.</p

Sensation of presence and cybersickness in applications of virtual reality for advanced rehabilitation

Around three years ago, in the special issue on augmented and virtual reality in rehabilitation, the topics of simulator sickness was briefly discussed in relation to vestibular rehabilitation. Simulator sickness with virtual reality applications have also been referred to as visually induced motion sickness or cybersickness. Recently, study on cybersickness has been reported in entertainment, training, game, and medical environment in several journals. Virtual stimuli can enlarge sensation of presence, but they sometimes also evoke unpleasant sensation. In order to safely apply augmented and virtual reality for long-term rehabilitation treatment, sensation of presence and cybersickness should be appropriately controlled. This issue presents the results of five studies conducted to evaluate visually-induced effects and speculate influences of virtual rehabilitation. In particular, the influence of visual and vestibular stimuli on cardiovascular responses are reported in terms of academic contribution

Personal customizing exercise with a wearable measurement and control unit

BACKGROUND: Recently, wearable technology has been used in various health-related fields to develop advanced monitoring solutions. However, the monitoring function alone cannot meet all the requirements of customizing machine-based exercise on an individual basis by relying on biosignal-based controls. We propose a new wearable unit design equipped with measurement and control functions to support the customization process. METHODS: The wearable unit can measure the heart rate and electromyogram signals during exercise performance and output workload control commands to the exercise machines. The workload is continuously tracked with exercise programs set according to personally customized workload patterns and estimation results from the measured biosignals by a fuzzy control method. Exercise programs are adapted by relying on a computer workstation, which communicates with the wearable unit via wireless connections. A prototype of the wearable unit was tested together with an Internet-based cycle ergometer system to demonstrate that it is possible to customize exercise on an individual basis. RESULTS: We tested the wearable unit in nine people to assess its suitability to control cycle ergometer exercise. The results confirmed that the unit could successfully control the ergometer workload and continuously support gradual changes in physical activities. CONCLUSION: The design of wearable units equipped with measurement and control functions is an important step towards establishing a convenient and continuously supported wellness environment