1,811 research outputs found
The Signature Triality of Majorana-Weyl Spacetimes
Higher dimensional Majorana-Weyl spacetimes present space-time dualities
which are induced by the Spin(8) triality automorphisms. Different signature
versions of theories such as 10-dimensional SYM's, superstrings, five-branes,
F-theory, are shown to be interconnected via the S_3 permutation group.
Bilinear and trilinear invariants under space-time triality are introduced and
their possible relevance in building models possessing a space-versus-time
exchange symmetry is discussed. Moreover the Cartan's ``vector/chiral
spinor/antichiral spinor" triality of SO(8) and SO(4,4) is analyzed in detail
and explicit formulas are produced in a Majorana-Weyl basis. This paper is the
extended version of hep-th/9907148.Comment: 28 pages, LaTex. Extended version of hep-th/990714
Variational Methods in AdS/CFT
We prove that the AdS/CFT calculation of 1-point functions can be drastically
simplified by using variational arguments. We give a simple universal proof,
valid for any theory that can be derived from a Lagrangian, that the large
radius divergencies in 1-point functions can always be renormalized away (at
least in the semiclassical approximation). The renormalized 1-point functions
then follow by a simple variational problem involving only finite quantities.
Several examples, a massive scalar, gravity, and renormalization flows, are
discussed. Our results are general and can thus be used for dualities beyond
AdS/CFT.Comment: 14 pages, no figures, LaTeX, minor change in footnot
Crystal Structure and Physical Properties of U3T3Sn4 (T = Ni, Cu) Single-Crystals
Heat capacity experiments, crystal structure determination and transmission
electron microscopy have been carried out on U3Cu3Sn4 single-crystals. U3Cu3Sn4
was confirmed to be a heavy-fermion antiferromagnet (TN=13(1) K) with a low
temperature electronic heat capacity coefficient gamma=390 mJ/molUK2. Low
temperature heat capacity experiments on a U3Ni3Sn4 single-crystal indicate
that below 0.4 K there is a crossover between the previously observed non-Fermi
liquid behavior and a Fermi liquid state.Comment: 12 pages (incl. 2 tables & 4 figures), to appear in Physica
Abdominal tuberculosis in Ecuador, a problem that is still not solved
Tuberculosis (TB) in the gastrointestinal tract or peritoneum is an uncommon condition in clinical practice. Its rarity, combined with its nonspecific presentations, makes this kind of extrapulmonary tuberculosis difficult to diagnose as it can mimic other inflammatory or malignant conditions. Delays in treatment and frequent misdiagnosis can lead to hazardous complications. In countries like Ecuador where the disease is endemic, TB should always be considered in the differential diagnosis of a patients who present with nonspecific abdominal symptoms. In these scenarios, laparoscopy can be an invaluable tool when used with sufficiently high clinical awareness and adequate training.
Case presentation: We present the case of a 37-year-old female patient from Ecuador with a 1-year history of abdominal pain, nausea, intermittent vomits, night sweats, and weight loss. After clinical evaluation and a laparoscopic intervention, abdominal TB was detected and promptly treated. Antituberculosis chemotherapy was initiated, and the patient successfully recovered.
Conclusions: High clinical awareness is imperative when approaching abdominal TB due to its wide spectrum of clinical symptoms and its rarity. Early detection and prompt treatment are critical to minimize the possibility of hazardous complications
Spectral characteristics of side face excited microstructured fibers for photonic integrated circuits formations
We propose a new method for mass production of the photonic crystal devices
on the basis of widely-known and well-developed technology such as
microstructured optical fibers. In this paper, we investigate the optical
properties of side-excited microstructured optical fiber and discuss the
conditions for utilization such a structure as a planar photonic crystal
device, namely, the high-quality resonance filter.Comment: 7 pages, 7 figure
Acute febrile illness is associated with Rickettsia spp infection in dogs
BACKGROUND: Rickettsia conorii is transmitted by Rhipicephalus sanguineus ticks and causes Mediterranean Spotted Fever (MSF) in humans. Although dogs are considered the natural host of the vector, the clinical and epidemiological significance of R. conorii infection in dogs remains unclear. The aim of this prospective study was to investigate whether Rickettsia infection causes febrile illness in dogs living in areas endemic for human MSF. METHODS: Dogs from southern Italy with acute fever (n = 99) were compared with case–control dogs with normal body temperatures (n = 72). Serology and real-time PCR were performed for Rickettsia spp., Ehrlichia canis, Anaplasma phagocytophilum/A. platys and Leishmania infantum. Conventional PCR was performed for Babesia spp. and Hepatozoon spp. Acute and convalescent antibodies to R. conorii, E. canis and A. phagocytophilum were determined. RESULTS: The seroprevalence rates at first visit for R. conorii, E. canis, A. phagocytophilum and L. infantum were 44.8%, 48.5%, 37.8% and 17.6%, respectively. The seroconversion rates for R. conorii, E. canis and A. phagocytophilum were 20.7%, 14.3% and 8.8%, respectively. The molecular positive rates at first visit for Rickettsia spp., E. canis, A. phagocytophilum, A. platys, L. infantum, Babesia spp. and Hepatozoon spp. were 1.8%, 4.1%, 0%, 2.3%, 11.1%, 2.3% and 0.6%, respectively. Positive PCR for E. canis (7%), Rickettsia spp. (3%), Babesia spp. (4.0%) and Hepatozoon spp. (1.0%) were found only in febrile dogs. The DNA sequences obtained from Rickettsia and Babesia PCRs positive samples were 100% identical to the R. conorii and Babesia vogeli sequences in GenBank®, respectively. Febrile illness was statistically associated with acute and convalescent positive R. conorii antibodies, seroconversion to R. conorii, E. canis positive PCR, and positivity to any tick pathogen PCRs. Fourteen febrile dogs (31.8%) were diagnosed with Rickettsia spp. infection based on seroconversion and/or PCR while only six afebrile dogs (12.5%) seroconverted (P = 0.0248). The most common clinical findings of dogs with Rickettsia infection diagnosed by seroconversion and/or PCR were fever, myalgia, lameness, elevation of C-reactive protein, thrombocytopenia and hypoalbuminemia. CONCLUSIONS: This study demonstrates acute febrile illness associated with Rickettsia infection in dogs living in endemic areas of human MSF based on seroconversion alone or in combination with PCR
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