Fishtail Effect Studied By Ac Susceptibility In Erba2cu3o7-δ Single Crystal

A study of the second magnetization peak (SMP) using a scaling procedure for ac susceptibility measurements, in an ErBa2Cu3O7-δ single crystal is presented. In addition, its sample size dependence, ac susceptibility (χ) is a very versatile technique, widely used in the study and characterization of superconducting materials. Its major advantages are the experimental simplicity, low cost, and great sensitivity.95313011306Berlincourt, T.G., Hake, R.R., Leslie, D.H., (1961) Phys. Rev. Lett., 6, p. 671Däumling, M., Seuntjens, J.M., Larbalestier, D.C., (1990) Nature (London), 346, p. 332Bean, C.P., (1962) Phys. Rev. Lett., 8, p. 250Bean, C.P., (1964) Rev. Mod. Phys., 36, p. 31Vargas, J.L., Larbalestier, D.C., (1992) Appl. Phys. Lett., 60, p. 1741Osofsky, M.S., Cohn, J.L., Skelton, E.F., Miller, M.M., Soulen Jr., R.J., Wolf, S.A., Vanderah, T.A., (1992) Phys. Rev. B, 45, p. 4916Harneit, W., (1996) Physica C, 267, p. 270Yeshurun, Y., Malozemoff, A.P., Shaulov, A., (1996) Rev. Mod. Phys., 68, p. 911Blatter, G., Feigel'man, M.V., Geshkenbein, V.B., Larkin, A.I., Vinokur, V.M., (1994) Rev. Mod. Phys., 66, p. 1125Krusin-Elbaum, L., Civale, L., Vinokur, V.M., Holtzberg, F., (1992) Phys. Rev. Lett., 69, p. 2280Yeshurun, Y., Bontemps, N., Burlachkov, L., Kapitulnik, A., (1994) Phys. Rev. B, 49, p. 1548Abulafia, Y., (1996) Phys. Rev. Lett., 77, p. 1596Farmer, J.W., Kornecki, M., Cowan, D.L., (2001) Physica C, 364, p. 334Mikitik, G.P., Brandt, E.H., (2001) Phys. Rev. B, 64, p. 184514Yamaguchi, Y., Shirakawa, N., Rajaram, G., Oka, K., Mumtaz, A., Obara, H., Nakagawa, T., Bando, H., (2001) Physica C, 361, p. 244Kopelevich, Y., Esquinazi, P., (1998) J. Low Temp. Phys., 113, p. 1Esquinazi, P., Setzer, A., Fuchs, D., Kopelevich, Y., Zeldov, E., Assmann, C., (1999) Phys. Rev. B, 60, p. 12454Gurevich, A., Vinokur, V.M., (1999) Phys. Rev. Lett., 83, p. 3037Cai, X.Y., Gurevich, A., Larbalestier, D.C., Kelley, R.J., Onellion, M., Berger, H., Margaritondo, G., (1994) Phys. Rev. B, 50, p. 16774Passos, W.A.C., Lisboa-Filho, P.N., Caparroz, R., De Faria, C.C., Venturini, P.C., Araujo-Moreira, F.M., Sergeenkov, S., Ortiz, W.A., (2001) Physica C, 354, p. 189(1991) Magnetic Susceptibility of Superconductors and Other Spin Systems, , edited by R. A. Hein, T. L. Francavilla, D. H. Liebenberg (Plenum, New York)Clem, J.R., Kerchner, H.R., Sekula, S.T., (1976) Phys. Rev. B, 14, p. 1893Ji, L., Sohn, H.R., Spalding, G.C., Lobb, C.J., Tinkham, M., (1989) Phys. Rev. B, 40, p. 10936Brandt, E.H., (1998) Phys. Rev. B, 58, p. 6506Brandt, E.H., (1998) Phys. Rev. B, 58, p. 6523De Lima, O.F., Cardoso, C.A., (2000) Phys. Rev. B, 61, p. 11722Cardoso, C.A., De Lima, O.F., (2000) Physica C, 334, p. 185Cardoso, C.A., Avila, M.A., Ribeiro, R.A., De Lima, O.F., (2001) Physica C, 354, p. 165Worthington, T.K., Gallagher, W.J., Dinger, T.R., (1987) Phys. Rev. Lett., 59, p. 1160Welp, U., Fleshler, S., Kwok, W.K., Klemm, R.A., Vinokur, V.M., Downey, J., Veal, B., Crabtree, G.W., (1991) Phys. Rev. Lett., 67, p. 3180Klein, L., Yacoby, E.R., Yeshurun, Y., Erb, A., Müller-Vogt, G., Breit, V., Wühl, H., (1994) Phys. Rev. B, 49, p. 4403Mochida, T., Murakami, M., (1997) Physica C, 290, p. 311Fàbrega, L., Fontcuberta, J., Civale, L., Piñol, S., (1994) Phys. Rev. B, 50, p. 1199Jönsson, B.J., Rao, K.V., Yun, S.H., Karlsson, U.O., (1998) Phys. Rev. B, 58, p. 5862Fàbrega, L., Fontcuberta, J., Piñol, S., Van Der Beek, C.J., Kes, P.H., (1993) Phys. Rev. B, 47, p. 15250Zeldov, E., Amer, N.M., Koren, G., Gupta, A., McElfresh, M.W., Gambino, R.J., (1990) Appl. Phys. Lett., 56, p. 680Hardy, V., Wahl, A., Ruyter, A., Maignan, A., Martin, C., Coudrier, L., Provost, J., Simon, Ch., (1994) Physica C, 232, p. 347Pashitski, A.E., (1997) Science, 275, p. 36

Anomaly Cancellation in Supergravity with Fayet-Iliopoulos Couplings

We review and clarify the cancellation conditions for gauge anomalies which occur when N=1, D=4 supergravity is coupled to a Kahler non-linear sigma-model with gauged isometries and Fayet-Iliopoulos couplings. For a flat sigma-model target space and vanishing Fayet-Iliopoulos couplings, consistency requires just the conventional anomaly cancellation conditions. A consistent model with non-vanishing Fayet-Iliopoulos couplings is unlikely unless the Green-Schwarz mechanism is used. In this case the U(1) gauge boson becomes massive and the D-term potential receives corrections. A Green-Schwarz mechanism can remove both the abelian and certain non-abelian anomalies in models with a gauge non-invariant Kahler potential.Comment: 27 page

Magnetic And Superconducting Properties Of Ru Sr2 Gd1.5 Ce0.5 Cu2 O10-δ Samples: Dependence On The Oxygen Content And Aging Effects

The magnetic and superconducting properties of Ru Sr2 Gd1.5 Ce0.5 Cu2 O10-δ polycrystalline samples with different oxygen-doping levels are presented. A strong suppression of the superconducting temperature (Tc), as well as a reduction in the superconducting fraction, occurs as the oxygen content is reduced by annealing the samples in oxygen-deprived atmospheres. Drastic changes in the electrical resistivity are observed above Tc, possibly associated with oxygen removal, mainly from grain boundaries. However, the magnetic ordering is relatively less affected by the changes in oxygen content of the samples. The spin-glass transition is enhanced and shifted to higher temperatures with the reduction in oxygen content. This could be correlated with an increase in the spin disorder and frustration for the oxygen-depleted samples. Also, the same oxygen-vacancy-induced disorder could explain the reduction in the fraction of the sample showing antiferromagnetic order. We also report significant changes in the measured properties of the samples as a function of time. © 2005 The American Physical Society.7113Felner, I., Asaf, U., Levi, Y., Millo, O., (1997) Phys. Rev. B, 55, p. 3374. , PRBMDO 0163-1829 10.1103/PhysRevB.55.R3374Bernhard, C., Tallon, J.L., Niedermayer, Ch., Blasius, Th., Golnik, A., Brücher, E., Kremer, R.K., Ansaldo, E.J., (1999) Phys. Rev. B, 59, p. 14099. , PRBMDO. 0163-1829. 10.1103/PhysRevB.59.14099Awana, V.P.S., Karppinen, M., Yamauchi, H., (2003) Studies of High Tc Superconductors, 46, p. 77. , edited by A. V. Narlikar (Nova Science Publishers, New YorkMatvejeff, M., Awana, V.P.S., Jang, L.-Y., Liu, R.S., Yamauchi, H., Karppinen, M., (2003) Physica C, 392-396, p. 87. , PHYCE6 0921-4534Cardoso, C.A., Araujo-Moreira, F.M., Awana, V.P.S., Kishan, H., Takayama-Muromachi, E., De Lima, O.F., (2004) Physica C, 405, p. 212. , PHYCE6 0921-4534Cardoso, C.A., Araujo-Moreira, F.M., Awana, V.P.S., Takayama-Muromachi, E., De Lima, O.F., Yamauchi, H., Karppinen, M., (2003) Phys. Rev. B, 67, p. 020407. , PRBMDO 0163-1829 10.1103/PhysRevB.67.020407Shi, L., Li, G., Fan, X.J., Feng, S.J., Li, X.-G., (2003) Physica C, 399, p. 69. , PHYCE6 0921-4534Felner, I., Asaf, U., Ritter, F., Klamut, P.W., Dabrowski, B., (2001) Physica C, 364-365, p. 368. , PHYCE6 0921-4534Felner, I., Asaf, U., Galstyan, E., (2002) Phys. Rev. B, 66, p. 024503. , PRBMDO 0163-1829 10.1103/PhysRevB.66.024503Felner, I., Asaf, U., Levi, Y., Millo, O., (2000) Physica C, 334, p. 141. , PHYCE6 0921-4534 10.1016/S0921-4534(00)00250-1Awana, V.P.S., Ansari, M.A., Gupta, A., Saxena, R.B., Kishan, H., Buddhikot, D., Malik, S.K., (2004) Phys. Rev. B, 70, p. 104520. , PRBMDO 0163-1829 10.1103/PhysRevB.70.104520Yoshizawa, H., Mitsuda, S., Aruga, H., Ito, A., (1987) Phys. Rev. Lett., 59, p. 2364. , PRLTAO 0031-9007 10.1103/PhysRevLett.59.2364Binder, K., Young, A.P., (1986) Rev. Mod. Phys., 58, p. 801. , RMPHAT 0034-6861 10.1103/RevModPhys.58.801Mydosh, J.A., (1993) Spin Glasses An Experimental Introduction, , Taylor & Francis, LondonFelner, I., Galstyan, E., Herber, R.H., Nowik, I., (2004) Phys. Rev. B, 70, p. 094504. , PRBMDO 0163-1829 10.1103/PhysRevB.70.094504Shengelaya, A., Khasanov, R., Eschenko, D.G., Felner, I., Asaf, U., Savić, I.M., Keller, H., Müller, K.A., (2004) Phys. Rev. B, 69, p. 024517. , PRBMDO. 0163-1829. 10.1103/PhysRevB.69.024517Xue, Y.Y., Cao, D.H., Lorenz, B., Chu, C.W., (2002) Phys. Rev. B, 65, p. 020511. , PRBMDO 0163-1829 10.1103/PhysRevB.65.02051

Structural And Magnetic Study Of Labacocu O5+δ

The structure and magnetic properties of the compound LaBaCuCo O5+δ have been studied for the non-stoichiometric oxygen concentration δ≈0.6. The structure is pseudo-cubic with a tripled perovskite unit cell. The crystal structure was determined by a combined Rietveld fit to neutron and synchrotron x-ray powder diffraction data in the orthorhombic Pmmm space group, with cell parameters a=3.9223 (3) Å, b=3.9360 (3) Å, c=11.7073 (8) Å, and V=180.74 (2) Å3 (room temperature). Antiferromagnetic ordering of Cu and Co magnetic moments is observed below 205 (4) K. The magnetic structure with cell aM =2a, bM =2b, and cM =2c, could be described with the Shubnikov space group Fmm m′. The magnetic moments of both equivalent Cu/Co sites were determined at 50 and 170 K to be 0.83 (3) μB and 0.58 (3) μB, respectively, consistent with one unpaired electron per atom. The fit of the intensities to a simple mean field magnetic model appeared to be insufficient to account for the variation of moments at temperatures close to TN while a three dimensional Heisenberg model could improve the fit. Susceptibility measurements between 4 and 350 K also show irreversibility below 150 K. The local environments of Cu and Co were studied by extended x-ray absorption fine structure spectroscopy at both absorption edges. Cu atoms adopt an elongated octahedral or square-based pyramidal oxygen environment which suggests mainly the presence of Cu(II) in the structure. Co adopts different local environments, depending on the electronic and spin states. © 2005 The American Physical Society.7114Er-Rakho, L., Michel, C., Lacorre, P., Raveau, B., (1988) J. 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In search of consensus: Terminology for entheseal changes (EC)

This article presents a consensus terminology for entheseal changes that was developed in English by an international team of scholars and then translated into French, Italian, Portuguese, Spanish and German. Use of a standard, neutral terminology to describe entheseal morphology will reduce misunderstandings between researchers, improve the reliability of comparisons between studies, and eliminate unwarranted etiological assumptions inherent in some of the descriptive terms presently used in the literature

Hydro-climatic and ecological behaviour of the drought of Amazonia in 2005

In 2005, southwestern Amazonia experienced the effects of an intense drought that affected life and biodiversity. Several major tributaries as well as parts of the main river itself contained only a fraction of their normal volumes of water, and lakes were drying up. The consequences for local people, animals and the forest itself are impossible to estimate now, but they are likely to be serious. The analyses indicate that the drought was manifested as weak peak river season during autumn to winter as a consequence of a weak summertime season in southwestern Amazonia; the winter season was also accompanied by rainfall that sometimes reached 25% of the climatic value, being anomalously warm and dry and helping in the propagation of fires. Analyses of climatic and hydrological records in Amazonia suggest a broad consensus that the 2005 drought was linked not to El Niño as with most previous droughts in the Amazon, but to warming sea surface temperatures in the tropical North Atlantic Ocean

Acute respiratory viral infections in pediatric cancer patients undergoing chemotherapy

AbstractObjectiveTo estimate the prevalence of infection by respiratory viruses in pediatric patients with cancer and acute respiratory infection (ARI) and/or fever.MethodsCross-sectional study, from January 2011 to December 2012. The secretions of nasopharyngeal aspirates were analyzed in children younger than 21 years with acute respiratory infections. Patients were treated at the Grupo em Defesa da Criança Com Câncer (Grendacc) and University Hospital (HU), Jundiaí, SP. The rapid test was used for detection of influenza virus (Kit Biotrin, Inc., Ireland), and real-time multiplex polymerase chain reaction (FTD, Respiratory pathogens, multiplex Fast Trade Kit, Malta) for detection of influenza virus (H1N1, B), rhinovirus, parainfluenza virus, adenovirus, respiratory syncytial virus, human parechovirus, bocavirus, metapneumovirus, and human coronavirus. The prevalence of viral infection was estimated and association tests were used (χ2 or Fisher's exact test).Results104 samples of nasopharyngeal aspirate and blood were analyzed. The median age was 12±5.2 years, 51% males, 68% whites, 32% had repeated ARIs, 32% prior antibiotic use, 19.8% cough, and 8% contact with ARIs. A total of 94.3% were in good general status. Acute lymphocytic leukemia (42.3%) was the most prevalent neoplasia. Respiratory viruses were detected in 50 samples: rhinoviruses (23.1%), respiratory syncytial virus AB (8.7%), and coronavirus (6.8%). Codetection occurred in 19% of cases with 2 viruses and in 3% of those with 3 viruses, and was more frequent between rhinovirus and coronavirus 43. Fever in neutropenic patients was observed in 13%, of which four (30.7) were positive for viruses. There were no deaths.ConclusionsThe prevalence of respiratory viruses was relevant in the infectious episode, with no increase in morbidity and mortality. Viral co-detection was frequent in patients with cancer and ARIs

String vacua with flux from freely-acting obifolds

A precise correspondence between freely-acting orbifolds (Scherk-Schwarz compactifications) and string vacua with NSNS flux turned on is established using T-duality. We focus our attention to a certain non-compact Z_2 heterotic freely-acting orbifold with N=2 supersymmetry (SUSY). The geometric properties of the T-dual background are studied. As expected, the space is non-Kahler with the most generic torsion compatible with SUSY. All equations of motion are satisfied, except the Bianchi identity for the NSNS field, that is satisfied only at leading order in derivatives, i.e. without the curvature term. We point out that this is due to unknown corrections to the standard heterotic T-duality rules.Comment: 13 pages, no figures; v2: references added and rearranged, version to appear in JHE

Acute Intestinal Obstruction Due To Gallstone Ileus [abdome Agudo Por Obstrução Por Ileobiliar]

Objective: Small bowel obstruction (SBO) due to gallstones (gallstone ileus) is an uncommon complication of cholelithiasis, for which there is no defined surgical procedure. The objective of this study was to perform a systematic review of the history, available image exams and clinical approach to the diagnosis and treatment of gallstone ileus. Method: We conducted a retrospective study in a university hospital including all cases of SBO treated over a period of 23 years. According to the surgical treatment, the patients were divided into two groups: (1) enterolithotomy with posterior cholecystectomy (two-stage surgery); and (2) enterolithotomy, cholecystectomy and fistula closure (one-stage surgery). Results: Twelve patients were included in the study, including 11 females (91,6%), with a mean age of 72.2 years. All patients presented associated diseases, mainly arterial hypertension (75%). All except one patient had multiple SBO symptoms. Gallstone ileus diagnosis was made before laparotomy in six patients (50%). There were eight patients in group 1 and four in group 2, and the morbidity was, respectively, 33.3% and 8.3%. Overall mortality was 16.6% (one patient in each group). Conclusion: Gallstone ileus should be suspected in the elderly with SBO symptoms. Early diagnosis can reduce post-operative complications. Treatment is urgent laparotomy and the surgical approach must be individualized for each case. 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