573 research outputs found
Subleading Soft Factor for String Disk Amplitudes
We investigate the behavior of superstring disk scattering amplitudes in the
presence of a soft external momentum at finite string tension. We prove that
there are no -corrections to the field theory form of the subleading
soft factor . At the end of this work, we also comment on the
possibility to find the corresponding subleading soft factors in closed string
theory using our result and the KLT relations.Comment: 15 pages, v2: minor changes, new references, version accepted by JHE
Bonus Yangian Symmetry for the Planar S-Matrix of N=4 Super Yang-Mills
Recent developments in the determination of the planar S-matrix of N=4 Super
Yang-Mills are closely related to its Yangian symmetry. Here we provide
evidence for a yet unobserved additional symmetry: the Yangian level-one
helicity operator.Comment: 8 pages, v2: minor change
Soft Black Hole Absorption Rates as Conservation Laws
The absorption rate of low-energy, or soft, electromagnetic radiation by
spherically symmetric black holes in arbitrary dimensions is shown to be fixed
by conservation of energy and large gauge transformations. We interpret this
result as the explicit realization of the Hawking-Perry-Strominger Ward
identity for large gauge transformations in the background of a non-evaporating
black hole. Along the way we rederive and extend previous analytic results
regarding the absorption rate for the minimal scalar and the photon.Comment: 20 Pages, 1 figur
Valence Fluctuation in CeMo2Si2C
We report on the valence fluctuation of Ce in CeMoSiC as studied
by means of magnetic susceptibility , specific heat , electrical
resistivity and x-ray absorption spectroscopy. Powder x-ray
diffraction revealed that CeMoSiC crystallizes in
CeCrSiC-type layered tetragonal crystal structure (space group
\textit{P4/mmm}). The unit cell volume of CeMoSiC deviates from the
expected lanthanide contraction, indicating non-trivalent state of Ce ions in
this compound. The observed weak temperature dependence of the magnetic
susceptibility and its low value indicate that Ce ions are in valence
fluctuating state. The formal Ce valence in CeMoSiC
= 3.11 as determined from x-ray absorption spectroscopy
measurement is well bellow the value 3.4 in
tetravalent Ce compound CeO. The temperature dependence of specific heat
does not show any anomaly down to 1.8 K which rules out any magnetic ordering
in the system. The Sommerfeld coefficient obtained from the specific heat data
is = 23.4 mJ/mol\,K. The electrical resistivity follows the
behavior in the low temperature range below 35 K confirming a Fermi
liquid behavior. Accordingly both the Kadowaki Wood ratio and
the Sommerfeld Wilson ratio are in the range expected for
Fermi-liquid systems. In order to get some information on the electronic
states, we calculated the band structure within the density functional theory,
eventhough this approach is not able to treat 4f electrons accurately. The
non- electron states crossing the Fermi level have mostly Mo 4d character.
They provide the states with which the 4f sates are strongly hybridized,
leading to the intermediate valent state.Comment: 18 pages, 10 figures Submitted to Journal of Alloys and Compound
Null Polygonal Wilson Loops in Full N=4 Superspace
We compute the one-loop expectation value of light-like polygonal Wilson
loops in N=4 super-Yang-Mills theory in full superspace. When projecting to
chiral superspace we recover the known results for tree-level
next-to-maximally-helicity-violating (NMHV) scattering amplitude. The one-loop
MHV amplitude is also included in our result but there are additional terms
which do not immediately correspond to scattering amplitudes. We finally
discuss different regularizations and their Yangian anomalies.Comment: 55 pages, v2: reference adde
Are yellow dung flies domesticated cow dung specialists?
The theory of niche differentiation implies some extent of specialization of species with regard to key resources, notably food. Coprophagous (dung-eating) insect larvae play a critical role in the decomposition of livestock dung in modern and traditional agricultural grasslands. The yellow dung fly (Scathophaga stercoraria L.; Diptera: Scathophagidae) is one of the largest, most common and abundant dung decomposers on pastures in cold-temperate regions across the entire northern hemisphere. As this fly is often associated with domesticated cattle or dairy cows, which are commonly kept for human nutrition worldwide (beef, milk, cheese, etc.), it is sometimes suspected to be a cow dung specialist. However, yellow dung flies are regularly active on and around other dung types, and must have reproduced on dung of wild vertebrates before the domestication of cattle. We therefore experimentally studied the performance of yellow dung fly larvae on dung of various large domestic vs. wild mammals (cow, horse, wild boar, red deer) in the laboratory in Switzerland. Larval performance in terms of juvenile survival, egg-to-adult development time, growth rate, and final adult body size, the major life history indicators of individual reproductive success, did not vary greatly among the various dung types tested. Thus, yellow dung flies can successfully reproduce on multiple types of mammal (vertebrate) dung, wild and domestic, and are therefore dung generalists rather than specialists. We conclude that yellow dung flies are common in European low- and highlands because they could plastically shift to dung of common herbivorous livestock after their domestication without losing the ability to reproduce on dung of common wild mammals
Stellenwert der pelvinen Lymphadenektomie beim klinisch lokalisierten Prostatakarzinom
Zusammenfassung: Der Stellenwert und die Ausdehnung der pelvinen Lymphadenektomie beim klinisch lokalisierten Prostatakarzinom werden weiterhin kontrovers diskutiert. Die Lymphadenektomie stellt jedoch bis heute die einzige Methode für ein exaktes Tumorstaging dar. Es gibt zunehmend Hinweise, dass das Entfernen von allen befallenen Lymphknoten einen positiven Einfluss auf das tumorfreie Überleben und evtl. auf das Gesamtüberleben haben könnte. Aus diesem Grund sollte, wenn eine Lymphadenektomie durchgeführt wird, diese Entlang der V.iliaca externa, in der Fossa obturatoria und beidseits Entlang der A.iliaca interna erfolge
- …