11,005 research outputs found
Lower dimensional volumes and the Kastler-Kalau-Walze type theorem for Manifolds with Boundary
In this paper, we define lower dimensional volumes of spin manifolds with
boundary. We compute the lower dimensional volume for
5-dimensional and 6-dimensional spin manifolds with boundary and we also get
the Kastler-Kalau-Walze type theorem in this case
A simple remark on a flat projective morphism with a Calabi-Yau fiber
If a K3 surface is a fiber of a flat projective morphisms over a connected
noetherian scheme over the complex number field, then any smooth connected
fiber is also a K3 surface. Observing this, Professor Nam-Hoon Lee asked if the
same is true for higher dimensional Calabi-Yau fibers. We shall give an
explicit negative answer to his question as well as a proof of his initial
observation.Comment: 8 pages, main theorem is generalized, one more remark is added,
mis-calculation and typos are corrected etc
The String Deviation Equation
The relative motion of many particles can be described by the geodesic
deviation equation. This can be derived from the second covariant variation of
the point particle's action. It is shown that the second covariant variation of
the string action leads to a string deviation equation.Comment: 18 pages, some small changes, no tables or diagrams, LaTex2
Increases in salience of ethnic identity at work: the roles of ethnic assignation and ethnic identification
To better understand how ethnicity is actually experienced within organisations, we examined reported increases in ethnic identity salience at work and responses to such increases. Thirty British black Caribbean graduate employees were interviewed about how and when they experienced their ethnic identity at work. The findings demonstrated that increased salience in ethnic identity was experienced in two key ways: through ‘ethnic assignation’ (a ‘push’ towards ethnic identity) and ‘ethnic identification’ (a ‘pull’ towards ethnic identity). We explore how and when ethnic assignation and ethnic identification occur at work, and their relevance to how workplaces are experienced by this group of minority ethnic employees. The findings suggest the need for further research attention to the dynamic and episodic nature of social identity, including ethnic identity, within organisations, and to the impact of such increases in salience of social identities on behaviour at work
Eye acupuncture for pain conditions: a scoping review of clinical studies.
Chinese eye acupuncture, focuses on treating different diseases by applying needle stimulation around the orbit of the eye. Since 1970, it has been used in China for the management of pain-related disorders. This scoping review systematically collected clinical studies on the use of eye acupuncture to treat pain conditions and identify any adverse events. Six databases including PubMed, the Cochrane Library, CNKI, VIP, Wan Fang Data and SinoMed were searched from 1970 to March 2019. Randomized controlled trials (RCTs), clinical controlled trials (CCTs) and case series on eye-acupuncture for pain conditions meeting the inclusion criteria were identified. Data were extracted on patients, interventions, details of eye acupuncture, control treatments and outcomes. Searches identified 81 clinical studies and a trend demonstrating an increasing number of published studies. All studies were conducted in China and published in Chinese. These included, 45 (55.6%) RCTs, 5 (6.2%) CCTs, and 31 (38.3%) case series, treating 7113 patients with 44 different pain-related diseases or symptoms. The most frequently reported conditions were headache (18, 16.2%), acute lumbar pain (7, 6.3%) and lumbar disc herniation (7, 6.3%). Treatment using small needles (φ0.25 × 13 mm), retained ≤30 min, needling the horizontal outer orbital edge and the avoidance of manipulation during treatment were the most frequent descriptions of the interventions used. Eye acupuncture was used alone in about half of the studies and of the remaining studies it was combined with other treatment. All studies suggested some beneficial effects including: pain relief, improved quality of life and mental health, and 18 (22.2%) adverse events. Eye acupuncture, predominantly studied in China, may be a promising intervention for managing diverse pain conditions. However, given the variety of study designs and reported treatment outcomes, conclusions about the evidence for eye acupuncture for specific conditions are not possible at this stage
Measurement of gamma p --> K+ Lambda and gamma p --> K+ Sigma0 at photon energies up to 2.6 GeV
The reactions gamma p --> K+ Lambda and gamma p --> K+ Sigma0 were measured
in the energy range from threshold up to a photon energy of 2.6 GeV. The data
were taken with the SAPHIR detector at the electron stretcher facility, ELSA.
Results on cross sections and hyperon polarizations are presented as a function
of kaon production angle and photon energy. The total cross section for Lambda
production rises steeply with energy close to threshold, whereas the Sigma0
cross section rises slowly to a maximum at about E_gamma = 1.45 GeV. Cross
sections together with their angular decompositions into Legendre polynomials
suggest contributions from resonance production for both reactions. In general,
the induced polarization of Lambda has negative values in the kaon forward
direction and positive values in the backward direction. The magnitude varies
with energy. The polarization of Sigma0 follows a similar angular and energy
dependence as that of Lambda, but with opposite sign.Comment: 21 pages, 25 figures, submitted to Eur. Phys. J.
Serendipitous XMM-Newton discovery of a cluster of galaxies at z=0.28
We report the discovery of a galaxy cluster serendipitously detected as an
extended X-ray source in an offset observation of the group NGC 5044. The
cluster redshift, z=0.281, determined from the optical spectrum of the
brightest cluster galaxy, agrees with that inferred from the X-ray spectrum
using the Fe K alpha complex of the hot ICM (z=0.27 +/- 0.01). Based on the 50
ks XMM observation, we find that within a radius of 383 kpc the cluster has an
unabsorbed X-ray flux, f_X (0.5-2 keV) = 3.34 (+0.08, -0.13) x 10^{-13}
erg/cm^2/s, a bolometric X-ray luminosity, L_X = 2.21 (+0.34, -0.19) x 10^{44}
erg/s, kT = 3.57 +/- 0.12 keV, and metallicity, 0.60 +/- 0.09 solar. The
cluster obeys the scaling relations for L_X and T observed at intermediate
redshift. The mass derived from an isothermal NFW model fit is, M_vir = 3.89
+/- 0.35 x 10^{14} solar masses, with a concentration parameter, c = 6.7 +/-
0.4, consistent with the range of values expected in the concordance
cosmological model for relaxed clusters. The optical properties suggest this
could be a ``fossil cluster''.Comment: 5 pages, 4 colour figures, accepted for publication in Ap
Novel Nonreciprocal Acoustic Effects in Antiferromagnets
The possible occurrence of nonreciprocal acoustic effects in antiferromagnets
in the absence of an external magnetic field is investigated using both (i) a
microscopic formulation of the magnetoelastic interaction between spins and
phonons and (ii) symmetry arguments. We predict for certain antiferromagnets
the existence of two new nonreciprocal (non-time invariant) effects:
A boundary-condition induced nonreciprocal effect and the occurrence of
transversal phonon modes propagating in opposite directions having different
velocities. Estimates are given and possible materials for these effects to be
observed are suggested.Comment: Euro. Phys. Lett. (in press
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