9,631 research outputs found
A Non-Principal Value Prescription for the Temporal Gauge
A non-principal value prescription is used to define the spurious
singularities of Yang-Mills theory in the temporal gauge. Typical one-loop
dimensionally-regularized temporal-gauge integrals in the prescription are
explicitly calculated, and a regularization for the spurious gauge divergences
is introduced. The divergent part of the one-loop self-energy is shown to be
local and has the same form as that in the spatial axial gauge with the
principal-value prescription. The renormalization of the theory is also briefly
mentioned.Comment: 13 pages, NCKU-HEP/93-0
Signatures of strong correlation effects in RIXS on Cuprates
Recently, spin excitations in doped cuprates are measured using the resonant
inelastic X-ray scattering (RIXS). The paramagnon dispersions show the large
hardening effect in the electron-doped systems and seemingly
doping-independence in the hole-doped systems, with the energy scales
comparable to that of the antiferromagnetic magnons. This anomalous hardening
effect was partially explained by using the strong coupling t-J model but with
a three-site term(Nature communications 5, 3314 (2014)). However we show that
hardening effect is a signature of strong coupling physics even without
including this extra term. By considering the t-t'-t"-J model and using the
Slave-Boson (SB) mean field theory, we obtain, via the spin-spin
susceptibility, the spin excitations in qualitative agreement with the
experiments. These anomalies is mainly due to the doping-dependent bandwidth.
We further discuss the interplay between particle-hole-like and paramagnon-like
excitations in the RIXS measurements.Comment: 7 pages, 6 figure
EFFECTS OF WHOLE BODY VIBRATION TRAINING ON KNEE EXTENSOR MUSCLE STRENGTH AND RATE OF FORCE DEVELOPMENT
This study compared the effects of 8-week whole-body vibration (WBV) training programs on knee extensor muscle strength and rate of force development. Twenty physically active male subjects were randomly assigned to a whole-body vibration training group (WBV; n =10) or a sham training group (SHAM; n = 10). Maximal voluntary isometric joint moment, rate of force development (RFD) and contractile impulse of the knee extensors were assessed before and after the training period. There were significant differences between WBV and sham groups on improvement percentage of maximum joint moment, RFD and
contractile impulse in knee extensor. We concluded that not only knee extensor muscle strength could be enhanced but also muscle contractile abilty could be faster after a 8-week WBV training program
HR practice, organisational commitment & citizenship behaviour in Taiwan
Purpose (mandatory) The study examines the relationships between HR practice (four aspects),
organisational commitment and citizenship behaviour at primary schools in Taiwan. The four HR
aspects include: (1) recruitment and placement (RP), (2) teaching, education and career
development (TEC), (3) support, communication and retention (SCR), and (4) performance and
appraisal (PA).
Design/methodology/approach (mandatory) With the assistance from the school HR managers and
using an anti-common method variance strategy, research data from 568 incumbent teachers in
Taiwan are collected, analysed and evaluated.
Findings (mandatory) Different from prior studies, highlighting the merits of HR practice, the study
discovers that HR practice may not necessarily contribute to citizenship behaviour. Teachers with
positive perceptions of RP and TEC are more likely to demonstrate citizenship behaviour, whereas
teachers with positive perceptions of SCR and PA are not. In addition, the study finds three
moderators: affective organisational commitment (AOC), rank of positions, and campus size. The
analysis shows that teachers with more AOC, higher positions and from smaller campus are more
likely to demonstrate OCB.
Originality/value (mandatory) The study provides a closer look at the HR-OCB relationship in
Taiwan. It reveals that a positive perception of HR practice may not necessarily contribute to OCB
occurrence. In addition, the results indicate that teachers have different views about varying HR
aspects. Specifically, aspects of recruitment and placement and teaching, education and career
development receive relatively higher levels of positive perception, whereas aspects of SCR and PA
receive relatively lower levels of positive perception. Questions arise as to whether HR practice
may lead to more OCB at primary schools. If this statement is true, school managers shall think
further of how to promote OCB using other policies, rather than relying on the HR practice
investigated here
EVALUATION OF ELBOW AND FOREARM MOTION BETWEEN SIDEARM AND OVERHAND PITCHING
This study is to analyze the differences in kinematics, electromyography (EMG) and ultrasonography between two types of pitchers. We intend to observe and simulate the muscles around glenohumeral and elbow joints in different pitching motions and hope to discover the connections and differences in between. 12 pitchers from the top level were recruited. Larger elbow flexion was found in sidearm pitchers during the acceleration phase. Decrease of the distance of nerve to medial epicondyle was also found as the elbow moved to a more flexed position. More anterior translation of the ulnar nerve might occur during acceleration phase. Slightly lower flexor carpi radialis (FCR) activity was displayed in sidearm pitchers, showing that FCR might play a less crucial role in protecting medial elbow by providing less varus torque
Emergence of topological phases from the extension of two-dimensional lattice with nonsymmorphic symmetries
Young and Kane have given a great insight for 2D Dirac semimetals with
nontrivial topology in the presence of nonsymmorphic crystalline symmetry.
Based on one of 2D nonsymmorphic square lattice structures they proposed, we
further construct a set of 3D minimal tight-binding models via vertically
stacking the 2D nonsymmorphic lattice. Specifically, our model provides a
platform to generate three topologically semimetallic phases such as Dirac
nodal line semimetals, Weyl nodal line semimetals and Weyl semimetals. The
off-centered mirror symmetry sufficiently protects nodal lines emerging within
mirror-invariant plane with a nontrivial mirror invariant ,
whereas twofold screw rotational symmetry protects nontrivial Weyl nodal points
with topological charge . Interestingly, Weyl nodal loops are generated
without mirror symmetry protection, where nontrivial "drumhead" surface states
emerge within loops. In the presence of both time-reversal and inversion
symmetries, the emergence of weak topological insulator phases is discussed as
well.Comment: 8 pages, 6 figures and 1 tabl
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