On the Temperature Dependence of the Shear Viscosity and Holography

We examine the structure of the shear viscosity to entropy density ratio eta/s in holographic theories of gravity coupled to a scalar field, in the presence of higher derivative corrections. Thanks to a non-trivial scalar field profile, eta/s in this setup generically runs as a function of temperature. In particular, its temperature behavior is dictated by the shape of the scalar potential and of the scalar couplings to the higher derivative terms. We consider a number of dilatonic setups, but focus mostly on phenomenological models that are QCD-like. We determine the geometric conditions needed to identify local and global minima for eta/s as a function of temperature, which translate to restrictions on the signs and ranges of the higher derivative couplings. Finally, such restrictions lead to an holographic argument for the existence of a global minimum for eta/s in these models, at or above the deconfinement transition.Comment: references adde

Three-loop HTL gluon thermodynamics at intermediate coupling

We calculate the thermodynamic functions of pure-glue QCD to three-loop order using the hard-thermal-loop perturbation theory (HTLpt) reorganization of finite temperature quantum field theory. We show that at three-loop order hard-thermal-loop perturbation theory is compatible with lattice results for the pressure, energy density, and entropy down to temperatures $T\simeq3\;T_c$. Our results suggest that HTLpt provides a systematic framework that can used to calculate static and dynamic quantities for temperatures relevant at LHC.Comment: 24 pages, 13 figs. 2nd version: improved discussion and fixing typos. Published in JHE

Early-Time Energy Loss in a Strongly-Coupled SYM Plasma

We carry out an analytic study of the early-time motion of a quark in a strongly-coupled maximally-supersymmetric Yang-Mills plasma, using the AdS/CFT correspondence. Our approach extracts the first thermal effects as a small perturbation of the known quark dynamics in vacuum, using a double expansion that is valid for early times and for (moderately) ultrarelativistic quark velocities. The quark is found to lose energy at a rate that differs significantly from the previously derived stationary/late-time result: it scales like T^4 instead of T^2, and is associated with a friction coefficient that is not independent of the quark momentum. Under conditions representative of the quark-gluon plasma as obtained at RHIC, the early energy loss rate is a few times smaller than its late-time counterpart. Our analysis additionally leads to thermally-corrected expressions for the intrinsic energy and momentum of the quark, in which the previously discovered limiting velocity of the quark is found to appear naturally.Comment: 39 pages, no figures. v2: Minor corrections and clarifications. References added. Version to be published in JHE

Poly (A)+ Transcriptome Assessment of ERBB2-Induced Alterations in Breast Cell Lines

We report the first quantitative and qualitative analysis of the poly (A)+ transcriptome of two human mammary cell lines, differentially expressing (human epidermal growth factor receptor) an oncogene over-expressed in approximately 25% of human breast tumors. Full-length cDNA populations from the two cell lines were digested enzymatically, individually tagged according to a customized method for library construction, and simultaneously sequenced by the use of the Titanium 454-Roche-platform. Comprehensive bioinformatics analysis followed by experimental validation confirmed novel genes, splicing variants, single nucleotide polymorphisms, and gene fusions indicated by RNA-seq data from both samples. Moreover, comparative analysis showed enrichment in alternative events, especially in the exon usage category, in ERBB2 over-expressing cells, data indicating regulation of alternative splicing mediated by the oncogene. Alterations in expression levels of genes, such as LOX, ATP5L, GALNT3, and MME revealed by large-scale sequencing were confirmed between cell lines as well as in tumor specimens with different ERBB2 backgrounds. This approach was shown to be suitable for structural, quantitative, and qualitative assessment of complex transcriptomes and revealed new events mediated by ERBB2 overexpression, in addition to potential molecular targets for breast cancer that are driven by this oncogene

Modelling the initiation of cleavage fracture of ferritic steels

The initiation of the cleavage fracture of ferritic steels at cracked grain boundary carbides situated in a plastic zone is modelled, using a 2D discrete dislocation simulation of the plastic zones associated with a microcrack under triaxial loading. Fracture is assumed to occur when the local stress intensity factor for the microcrack equals KIC. For microcracks in the size range 0.1-10 μm, the applied stress at fracture, σF, is found to be independent of the yield stress (in the range 200-1600 MPa) and therefore of temperature. The dependence of σF on the crack size deviates from a Griffith type relation. These predictions are consistent with experimental data on steels in the literature. The values of σF predicted are in good agreement with the experimental values. The results suggest that only a small fraction of carbides are in configurations leading to fracture. © 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved

A aplicação de adesivo de cianoacriato por histeroscopia e os testes de perviedade na esterilização tubária de ovelhas

Objetivo: avaliar, por meio de testes de prenhez e de perviedade, a eficácia da obstrução tubária de ovelhas com adesivo de cianoacrilato aplicado por via histeroscópica. Método: 12 ovelhas adultas, com uma gestação anterior, foram distribuídas em três grupos: G-PO (n=3) submetidas à laqueadura tubária tipo Pomeroy; G-SH (n=3) aplicação de solução salina no istmo tubário por histeroscopia, e G-AD (n=6) aplicação de 0,5mL de n-butil-2-cianoacrilato no interior do istmo tubário, por histeroscopia. Depois de acasaladas por 90 dias com machos de comprovada fertilidade, as ovelhas não prenhas foram submetidas à laparotomia, retiradas as tubas uterinas, medidos os seus diâmetros e preparadas para testes de perviedade pela aplicação de azul de metileno e de pressão hidráulica (80mmHg). Resultados: As ovelhas de G-PO e G-AD não ficaram prenhas (0%), em contraste com as SH (100%). O GPO apresentou maior concentração de aderências (66,6%) e de granulomas (100%) em relação ao grupo AD (0%); o adesivo manteve-se íntegro no lúmen tubário. O diâmetro da tuba uterina em G-AD (0,650 ± 0,16 cm) foi significantemente maior do que o das tubas em G-PO (0,195 ± 0,04* cm) (p=0,01). Os testes de perviedade de pressão e corante foram negativos para todo o grupo PO e somente um animal em AD mostrou-se positivo para o teste de pressão. Conclusão: a aplicação histeroscópica de cianoacrilato no lúmen tubário de ovelhas impediu eficientemente a fecundação, constituindo procedimento eficaz e de boas perspectivas para aplicação futura em humanos.Background: To evaluate, through pregnancy and pressure burst tests, the effectiveness of sheep uterine tube sterilization through hysteroscopic insertion of cyanoacrylate adhesive. Methods: Adult sheep (n=12), with one previous pregnancy, were distributed as follows: PO Group (n=3) submitted to laparotomy and Pomeroy surgical procedure of tubal obstruction, Group SH (n=3) submitted to hysteroscopy application of saline solution inside the tubal isthmus, and Group AD (n=6) submitted to hysteroscopy application of 0.5 mL of n-2-butil-cyanoacrylate inside the tubal isthmus. They were allowed to copulate with fertile males during ninety days. The non pregnant sheep, at the 90th day, were submitted to laparotomy, the uterine tubes were removed and their diameters analyzed. The uterine tubes were evaluated for patency with methylene blue dye injection. The overpressure burst test (80mmHg) was then applied through the uterine cervix. Data were evaluated by t Student and Fisher test. Results: All sheep from groups PO and AD did not get pregnant (0%) in contrast with sheep from group SH (100%); the adhesive remained stable inside the tubal lumen. The diameter of the proximal tube in AD group (0.650 ± 0.16cm) was significantly wider than the PO group (0.195 ± 0.04* cm) (p= 0.01). The overpressure burst and dye patency tests were negative for all animals from PO group and only one animal in AD group was positive for the pressure burst test. Conclusion: The hysteroscopic insertion of cyanoacrylate inside the tubal lumen of the sheep was effective to obstruct the uterine tube and to promote the sterilization, and would be an option for future applying in human beings

Hysteroscopic sterilization with occlusion of sheep uterine tube using n-butyl-2-cyanoacrylate adhesive

Purpose: To evaluate the fertility and analyze the macroscopic, microscopic and morphometric aspects of sheep uterine tube sterilization with a hysteroscopically insert of n-butyl-2-cyanoacrylate adhesive. Methods: 12 adult sheep, with one previous pregnancy, were distributed as follows: group L (n=3) subjected to laparotomy and Pomeroy uterine tube ligation, group S (n=3) subjected to hysteroscopic application of saline solution in tube isthmus and group AD(n=6), that was subjected to hysteroscopic application of 0.5 ml of n-2-butil-cyanoacrylate in tube isthmus. They were mated with fertile males for ninety days. The non pregnant sheep, at the 90th day, were subjected to laparotomy with uterus and tubes uterine resection. The fragments of uterine tubes were fixated in 10% formalin and processes for histology evaluated, and slices dyes for H.E. Data were evaluated by Wilcoxon and Mann-Whitney and Fisher’s exact test. Results: All sheep from groups L and AD did not get pregnant (0%) in contrast with sheep from group S (100%); the adhesive remained integral in the uterine tube lumen. The percentual of adherences (66.6%) and fibrosis responses (100%) was significantly higher in the group L than group AD (0%) (p≤0.01). The diameter of the caudal tube in group AD (2652.15 ± 45.76 mm) was significantly wider than that of the group L (1868.27 ± 56.11* mm) (p ≤ 0.05). Conclusion: The hysteroscopic insertion of cyanoacrylate in the uterine tube lumen of sheep was effective to obstruct the uterine tube and to promote the sterilization.Objetivo: Avaliar a fertilidade e aspectos macroscópicos, microscópicos e morfométricos da esterilização histeroscópica de tubas uterinas de ovelhas com o adesivo de n-butil-2-cianoacrilato. Métodos: 12 ovelhas adultas, com uma prenhez anterior, foram distribuídas como segue: o grupo L (n=3) submetidas à laparotomia e laqueadura tipo Pomeroy, grupo S (n=3) submetidas à aplicação histeroscópica de solução salina no istmo tubário e grupo AD (n=6), com aplicação histeroscópica de 0,5 ml de cianoacrilato. As ovelhas foram acasaladas com machos de comprovada fertilidade por noventa dias. As ovelhas não prenhes aos 90 dias, foram submetidas à laparotomia com ressecção do útero e tubas uterinas, que foram fixadas em formalina 10%s e os cortes histológicos corados em hematoxilina/eosina. Os resultados foram avaliados pelo teste de Wilcoxon e teste exato de Fisher. Resultados: Todas as ovelhas dos grupos L e AD não ficaram prenhes (0%) ao contrário das ovelhas do grupo S (100%); o adesivo permaneceu íntegro no lúmen tubário. O percentual de aderências (66.6%) e de fibrose (100%) foi significativamente maior no grupo L do que no grupo AD (0%) (p≤0,01). O diâmetro da porção caudal no grupo AD (2652,15 ± 45,76 mm) foi significativamente maior do que grupo L (1868,27 ± 56.11 mm) (p≤0,05). Conclusão: A inserção histeroscópica do cianoacrilato no lúmen tubário de ovelhas foi eficaz para obstruir a tuba uterina e promover a esterilização