Effective Action for QED with Fermion Self-Interaction in D=2 and D=3 Dimensions

In this work we discuss the effect of the quartic fermion self-interaction of Thirring type in QED in D=2 and D=3 dimensions. This is done through the computation of the effective action up to quadratic terms in the photon field. We analyze the corresponding nonlocal photon propagators nonperturbatively in % \frac{k}{m}, where k is the photon momentum and m the fermion mass. The poles of the propagators were determined numerically by using the Mathematica software. In D=2 there is always a massless pole whereas for strong enough Thirring coupling a massive pole may appear . For D=3 there are three regions in parameters space. We may have one or two massive poles or even no pole at all. The inter-quark static potential is computed analytically in D=2. We notice that the Thirring interaction contributes with a screening term to the confining linear potential of massive QED_{2}. In D=3 the static potential must be calculated numerically. The screening nature of the massive QED$_{3}$ prevails at any distance, indicating that this is a universal feature of % D=3 electromagnetic interaction. Our results become exact for an infinite number of fermion flavors.Comment: Latex, 13 pages, 3 figure

Asymptotically Improved Convergence of Optimized Perturbation Theory in the Bose-Einstein Condensation Problem

We investigate the convergence properties of optimized perturbation theory, or linear $\delta$ expansion (LDE), within the context of finite temperature phase transitions. Our results prove the reliability of these methods, recently employed in the determination of the critical temperature T_c for a system of weakly interacting homogeneous dilute Bose gas. We carry out the explicit LDE optimized calculations and also the infrared analysis of the relevant quantities involved in the determination of $T_c$ in the large-N limit, when the relevant effective static action describing the system is extended to O(N) symmetry. Then, using an efficient resummation method, we show how the LDE can exactly reproduce the known large-N result for $T_c$ already at the first non-trivial order. Next, we consider the finite N=2 case where, using similar resummation techniques, we improve the analytical results for the nonperturbative terms involved in the expression for the critical temperature allowing comparison with recent Monte Carlo estimates of them. To illustrate the method we have considered a simple geometric series showing how the procedure as a whole works consistently in a general case.Comment: 38 pages, 3 eps figures, Revtex4. Final version in press Phys. Rev.

Cytotoxic Effects Of Zoledronic Acid On Human Epithelial Cells And Gingival Fibroblasts

Bisphosphonate-induced osteonecrosis has been related to the cytotoxicity of these drugs on oral mucosa cells. A previous study showed that 5 μM of zoledronic acid (ZA), a nitrogen-containing bisphosphonate, is the highest concentration of this drug found in the oral cavity of patients under treatment. Therefore, in order to simulate an osteonecrosis clinical condition, the aim of this study was to evaluate the highest concentration of ZA applied on human epithelial cells (HaCaT) and gingival fibroblasts. For this purpose, cells (3x104 cells/cm2) were seeded in wells for 48 h using complete culture medium (cDMEM). After 48 h incubation, the cDMEM was replaced by fresh serum-free culture medium (DMEM-FBS) in which the cells were maintained for additional 24 h. Then, 5 μM ZA were added to the DMEM-FBS and the cells incubated in contact with the drug for 48 h. After this period, the number of viable cells (trypan blue), cell viability (MTT assay), total protein (TP) production and cell morphology (SEM analysis) were assessed. Data were analyzed statistically by Mann-Whitney, ANOVA and Tukey's test (α=0.05). ZA caused a significant reduction in the number of viable cells and decreased the metabolic activity of both cell lines. However, decrease of TP production occurred only in the epithelial cell cultures. Morphological alterations were observed in both cell types treated with ZA. In conclusion, ZA (5 μM) was cytotoxic to human epithelial cells and gingival fibroblast cultures, which could be associated, clinically, with the development of bisphosphonateinduced osteonecrosis.246551558Civitelli, R., Napoli, N., Armamento-Villareal, R., Use of intravenous bisphosphonates in osteoporosis (2007) Curr Osteoporos Rep, 5, pp. 8-13Cohen, S.B., An update on bisphosphonates (2004) Curr Rheumatol Rep, 6, pp. 59-65Rogers, M.J., Watts, D.J., Russel, R.G., Overview of bisphosphonates (1997) Cancer, 80, pp. 1652-1660Rogers, M.J., Gordon, S., Benford, H.L., Coxon, F.P., Luckman, S.P., Monkkonen, J., Cellular and molecular mechanisms of action of bisphosphonates (2000) Cancer Supl, 88, pp. 2961-2978Lawson, M.A., Xia, Z., Barnett, B.L., Triffitt, J.T., Phipps, R.J., Dunford, J.E., Differences between bisphosphonates in binding affinities for hydroxyapatite (2010) J Biomed Mater Res Part B: Appl Biomater, 92, pp. 149-155Allen, M.R., Burr, D.B., The pathogenesis of bisphosphonate-related osteonecrosis of the jaw: So many hypotheses, so few data (2009) J Oral Maxillofac Surg, 67, pp. 61-70Otto, S., Pautke, C., Opelz, C., Wesphal, I., Drosse, I., Swager, J., Osteonecrosis of the jaw: Effects of bisphosphonate type, local concentration, and acidic milieu on the pathomechanism (2010) J Oral Maxillofac Surg, 68, pp. 2837-2845Reid, I.R., Booland, M.J., Is bisphosphonate-associated osteonecrosis of the jaw caused by soft tissue toxicity? (2007) Bone, 41, pp. 318-320Scheper, M.A., Badros, A., Chausparat, R., Cullen, K.J., Meiller, T.F., Effect of zoledronic acid on oral fibroblasts and epithelial cells: A potential mechanism of bisphosphonate-associated osteonecrosis (2009) Br J Haematol, 144, pp. 667-676Scheper, M.A., Badros, A., Salama, A.R., Wartburton, G., Cullen, K.J., Weikel, D.S., A novel bioassay model to determine clinically significant bisphosphonate levels (2009) Support Care Cancer, 17, pp. 1553-1557Ruggiero, S.L., Mehrotra, B., Rosenberg, T.J., Engroff, S.L., Osteonecrosis of the jaws associated with the use of bisphosphonates: A review of 63 cases (2004) J Oral Maxillofac Surg, 62, pp. 527-534Walter, C., Klein, M.O., Pabst, A., Al-Nawas, B., Duscher, H., Ziebart, T., Influence of bisphosphonates on endothelial cells, fibroblasts, and osteogenic cells (2010) Clin Oral Investig, 14, pp. 35-41Kumar, S.K.S., Gorur, A., Schaauddin, C., Shuler, C.F., Costerton, J.W., Sedghizadeh, P.P., The role of microbial biofilms in osteonecrosis of the jaw associated with bisphosphonate therapy (2010) Curr Osteoporos Rep, 8, pp. 40-48Aas, J.A., Paster, B.J., Stokes, L.N., Olsen, I., Dewhirst, F.E., Defining the normal bacterial flora of the oral cavity (2005) J Clin Microbiol, 43, pp. 5721-5732Basso, F.G., Pansani, T.N., Turrioni, A.P.S., Bagnato, V.S., Hebling, J., de Souza Costa, C.A., In vitro wound healing improvement by low-level laser therapy application in cultured gingival fibroblasts (2012) Int J Dent, , [Epub ahead of print. DOI: 10.1155/2012/719452]Wiegand, C., Hipler, U., Methods for the measurement of cell and tissue compatibility including tissue regeneration process (2008) GMS Krankenhhyg Interdiszip, 3, pp. 1863-5245Basso, F.G., Oliveira, C.F., Kurachi, C., Hebling, J., de Souza Costa, C.A., Biostimulatory effect of low-level laser therapy on keratinocytes in vitro (2013) Lasers Med Sci, 28, pp. 367-374De Souza Costa, C.A., Duarte, P.T., de Souza, P.P., Giro, E.M., Hebling, J., Cytotoxic effects and pulpal response caused by a mineral trioxide aggregate formulation and calcium hydroxide (2008) Am J Dent, 21, pp. 255-261Oliveira, C.F., Basso, F.G., Lins, E.C.C., Kurachi, C., Hebling, J., Bagnato, V.S., Increased viability of odontoblast-like cells subjected to low-level laser irradiation (2010) Laser Phys, 20, pp. 1659-1666Read, S.M., Northcote, D.H., Minimization of variation in the response to different proteins of the Coomassie blue G dye-binding assay for protein (1981) Anal Biochem, 116, pp. 53-64Oliveira, C.F., Basso, F.G., Lins, E.C., Kurachi, C., Hebling, J., Bagnato, V.S., In vitro effect of low-level laser on odontoblast-like cells (2011) Laser Phys Lett, 8, pp. 155-163Simon, M.J.K., Niehoff, P., Kimming, B., Wiltfang, J., Açil, Y., Expression profile and synthesis of different collagen types I, II III and V of human gingival fibroblasts, osteoblasts, ans SaOs-2 cells after bisphosphonate treatment (2010) Clin Oral Investig, 14, pp. 51-58Migliorati, C.A., Siegel, M.A., Elting, L.S., Bisphosphonate-associated osteonecrosis: A long-term complication of bisphosphonate treatment (2006) Lancet Oncol, 7, pp. 508-514Werner, S., Krieg, T., Smola, H., Keratinocyte-fibroblast interactions in wound healing (2007) J Investigative Dermatol, 127, pp. 998-1008Ravosa, M.J., Ning, J., Liu, Y., Stack, M.S., Bisphosphonate effects on the behavior of oral epithelial cells and oral fibroblasts (2011) Arch Oral Biol, 56, pp. 491-49

Selective Reflection Spectroscopy at the Interface between a Calcium Fluoride Window and Cs Vapour

A special vapour cell has been built, that allows the measurement of the atom-surface van der Waals interaction exerted by a CaF2 window at the interface with Cs vapour. Mechanical and thermal fragility of fluoride windows make common designs of vapour cells unpractical, so that we have developed an all-sapphire sealed cell with an internal CaF2 window. Although impurities were accidentally introduced when filling-up the prototype cell, leading to a line-broadening and shift, the selective reflection spectrum on the Cs D1 line (894 nm) makes apparent the weak van der Waals surface interaction. The uncertainties introduced by the effects of these impurities in the van der Waals measurement are nearly eliminated when comparing the selective reflection signal at the CaF2 interface of interest, and at a sapphire window of the same cell. The ratio of the interaction respectively exerted by a sapphire interface and a CaF2 interface is found to be 0.55 $\pm$ 0.25, in good agreement with the theoretical evaluation of ~0.67.Comment: soumis \`a Appl Phys B MS 4734

BEC Collapse and Dynamical Squeezing of Vacuum Fluctuations

We analyze the phenomena of Bose Novae, as described by Donley et al [Nature 412, 295 (2001)], by focusing on the behavior of excitations or fluctuations above the condensate, as driven by the dynamics of the condensate (rather than the dynamics of the condensate alone or the kinetics of the atoms). The dynamics of the condensate squeezes and amplifies the quantum excitations, mixing the positive and negative frequency components of their wave functions thereby creating particles which appear as bursts and jets. By analyzing the changing amplitude and particle content of these excitations, our simple physical picture (based on a test field approximation) explains well the overall features of the Bose Novae phenomena and provide excellent quantitative fits with experimental data on several aspects, such as the scaling behavior of the collapse time and the amount of particles in the jet. The predictions of the bursts at this level of approximation is less than satisfactory but may be improved on by including the backreaction of the excitations on the condensate. The mechanism behind the dominant effect -- parametric amplification of vacuum fluctuations and freezing of modes outside of horizon -- is similar to that of cosmological particle creation and structure formation in a rapid quench (which is fundamentally different from Hawking radiation in black holes). This shows that BEC dynamics is a promising venue for doing `laboratory cosmology'.Comment: Latex 36 pages, 6 figure

Os sistemas agroflorestais como alternativa de sustentabilidade em ecossistemas de várzea no Amazonas.

Os sistemas agroflorestais (SAFs) representam uma alternativa agroecológica de produção, sob regime sustentável, para os agricultores familiares na várzea dos Rios Solimões/Amazonas, principalmente no que se refere ao manejo florestal, à diversidade de produtos e à geração de renda. Diante disso, o objetivo deste trabalho foi compreender as diferentes formas de apropriação e de manejo dos recursos naturais através dos SAFs, nos subsistemas roça, sítio e lagos, como componente para a sustentabilidade dos agricultores familiares da localidade Costa da Terra Nova, município do Careiro da Várzea, Amazonas. O método empregado foi o Estudo de Caso com aplicação de questionários, entrevistas e observação participante. A produção familiar na Costa da Terra Nova é representada pelos SAFs, constituído pelos os subsistemas: roça quintal e lago, que proporcionam produtos tanto para subsistência quanto para comercialização local, e estabelecendo a agricultura como fundamental atividade na localidade. O principal produto para comercialização é obtido das hortaliças cultivadas na época da vazante no subsistema roça nas comunidades São Francisco e Nossa Senhora da Conceição; e do extrativismo pesqueiro no subsistema lago, na época da cheia, principalmente na comunidade São José. A criação de animal se dá no subsistema sítio e é apenas para subsistência, sendo as aves e os suínos os principais animais domésticos criados nas três comunidades. Portanto os SAFs tradicionais, constituídos pelos subsistemas, roça, sitio e lago, são responsáveis pela sustentabilidade socioeconômica da localidade pesquisada, servindo, como alternativa agrícola melhor adaptada às condições locais das áreas de várzea na Amazônia

Pharmacokinetic-pharmacodynamic correlation of imipenem in pediatric burn patients using a bioanalytical liquid chromatographic method

A bioanalytical method was developed and applied to quantify the free imipenem concentrations for pharmacokinetics and PK/PD correlation studies of the dose adjustments required to maintain antimicrobial effectiveness in pediatric burn patients. A reverse-phase Supelcosil LC18 column (250 x 4.6 mm 5 micra), binary mobile phase consisting of 0.01 M, pH 7.0 phosphate buffer and acetonitrile (99:1, v/v), flow rate of 0.8 mL/min, was applied. The method showed good absolute recovery (above 90%), good linearity (0.25-100.0 µg/mL, r2=0.999), good sensitivity (LLOQ: 0.25 µg/mL; LLOD: 0.12 µg/mL) and acceptable stability. Inter/intraday precision values were 7.3/5.9%, and mean accuracy was 92.9%. A bioanalytical method was applied to quantify free drug concentrations in children with burns. Six pediatric burn patients (median 7.0 years old, 27.5 kg), normal renal function, and 33% total burn surface area were prospectively investigated; inhalation injuries were present in 4/6 (67%) of the patients. Plasma monitoring and PK assessments were performed using a serial blood sample collection for each set, totaling 10 sets. The PK/PD target attained (40%T>MIC) for each minimum inhibitory concentration (MIC: 0.5, 1.0, 2.0, 4.0 mg/L) occurred at a percentage higher than 80% of the sets investigated and 100% after dose adjustment. In conclusion, the purification of plasma samples using an ultrafiltration technique followed by quantification of imipenem plasma measurements using the LC method is quite simple, useful, and requires small volumes for blood sampling. In addition, a small amount of plasma (0.25 mL) is needed to guarantee drug effectiveness in pediatric burn patients. There is also a low risk of neurotoxicity, which is important because pharmacokinetics are unpredictable in these critical patients with severe hospital infection. Finally, the PK/PD target was attained for imipenem in the control of sepsis in pediatric patients with burns.</p

Evolution of the differential transverse momentum correlation function with centrality in Au+Au collisions at sNN=200\sqrt{s_{NN}} = 200 GeV

We present first measurements of the evolution of the differential transverse momentum correlation function, {\it C}, with collision centrality in Au+Au interactions at $\sqrt{s_{NN}} = 200$ GeV. {\it C} exhibits a strong dependence on collision centrality that is qualitatively similar to that of number correlations previously reported. We use the observed longitudinal broadening of the near-side peak of {\it C} with increasing centrality to estimate the ratio of the shear viscosity to entropy density, $\eta/s$, of the matter formed in central Au+Au interactions. We obtain an upper limit estimate of $\eta/s$ that suggests that the produced medium has a small viscosity per unit entropy.Comment: 7 pages, 4 figures, STAR paper published in Phys. Lett.