Interacting holographic tachyon model of dark energy

We propose a holographic tachyon model of dark energy with interaction between the components of the dark sector. The correspondence between the tachyon field and the holographic dark energy densities allows the reconstruction of the potential and the dynamics of the tachyon scalar field in a flat Friedmann-Robertson-Walker universe. We show that this model can describe the observed accelerated expansion of our universe with a parameter space given by the most recent observational results.Comment: 7 pages, 8 figures, accepted for publication in IJMP

Limits on the Superconducting Order Parameter in NdFeAsO1−x_{1-x}Fy_y from Scanning SQUID Microscopy

Identifying the symmetry of the superconducting order parameter in the recently-discovered ferro-oxypnictide family of superconductors, RFeAsO$_{1-x}$F$_{y}$, where $R$ is a rare earth, is a high priority. Many of the proposed order parameters have internal $\pi$ phase shifts, like the d-wave order found in the cuprates, which would result in direction-dependent phase shifts in tunnelling. In dense polycrystalline samples, these phase shifts in turn would result in spontaneous orbital currents and magnetization in the superconducting state. We perform scanning SQUID microscopy on a dense polycrystalline sample of \NdFeAsO$_{0.94}$F$_{0.06}$ with $T_c=48$ K and find no such spontaneous currents, ruling out many of the proposed order parameters.Comment: 10 pages, 5 figures; to appear in JPS

Coating of Magnetite Nanoparticles with Fucoidan to Enhance Magnetic Hyperthermia Efficiency

Magnetic nanoparticles (NP), such as magnetite, have been the subject of research for application in the biomedical field, especially in Magnetic Hyperthermia Therapy (MHT), a promising technique for cancer therapy. NP are often coated with different compounds such as natural or synthetic polymers to protect them from oxidation and enhance their colloidal electrostatic stability while maintaining their thermal efficiency. In this work, the synthesis and characterization of magnetite nanoparticles coated with fucoidan, a biopolymer with recognized biocompatibility and antitumoral activity, is reported. The potential application of NP in MHT was evaluated through the assessment of Specific Loss Power (SLP) under an electromagnetic field amplitude of 14.7 kA m−1 and at 276 kHz. For fucoidan-coated NP, it was obtained SLP values of 100 and 156 W/g, corresponding to an Intrinsic Loss Power (ILP) of 1.7 and 2.6 nHm2kg−1, respectively. These values are, in general, higher than the ones reported in the literature for non-coated magnetite NP or coated with other polymers. Furthermore, in vitro assays showed that fucoidan and fucoidan-coated NP are biocompatible. The particle size (between ca. 6 to 12 nm), heating efficiency, and biocompatibility of fucoidan-coated magnetite NP meet the required criteria for MHT application

Magnetic resonance imaging of the temporomandibular joint acquired using different parameters

Introduction: Magnetic resonance imaging (MRI) is considered the examination of choice for the diagnosis of abnormalities in the TMJ. Considering the difficulty in defining and standardizing the diagnostic criteria, and the need for more accurate and reliable diagnosis of conditions in the TMJ, the aim of the present study was to compare three different MRI parameters: T1-weighted, T2-weighted and proton density–weighted in the diagnosis of changes in the temporomandibular joint.Materials and Methods: Fifty magnetic resonance imaging examinations of the temporomandibular joint (100 temporomandibular joints) were conducted according to a protocol that evaluates disc position, disc function and bone abnormalities. The images were obtained bilaterally in parasagittal sections in closed and open mouth positions in the three studied parameters Three trained oral radiologists assessed all the images. Reliability of the intra- and inter-examiner response was analyzed using the concordance test (Fleiss’ kappa; α = 0.05).Results: The reliability of the response patterns between observers for different protocols varied from very good to good. Observers were less constant in their response patterns when assessing proton density–weighted images. There was very good agreement for disc morphology, cortical bone and bone structures/functions; however, there was wide variation for medullary bone marrow signs.Conclusion: T2-weighted imaging was found to be the best examination to assess the medullary bone. For evaluating of disc morphology, cortical bone and bone structures/functions, any protocol is indicated once the protocol does not interfere with the analysis.Magnetic resonance imaging (MRI) is considered the examination of choice for the diagnosis of abnormalities in the TMJ. Considering the difficulty in defining and standardizing the diagnostic criteria, and the need for more accurate and reliable diagnosis of conditions in the TMJ, the aim of the present study was to compare three different MRI parameters: T1-weighted, T2-weighted and proton density–weighted in the diagnosis of changes in the temporomandibular joint. Fifty magnetic resonance imaging examinations of the temporomandibular joint (100 temporomandibular joints) were conducted according to a protocol that evaluates disc position, disc function and bone abnormalities. The images were obtained bilaterally in parasagittal sections in closed and open mouth positions in the three studied parameters Three trained oral radiologists assessed all the images. Reliability of the intra- and inter-examiner response was analyzed using the concordance test (Fleiss’ kappa; α = 0.05). The reliability of the response patterns between observers for different protocols varied from very good to good. Observers were less constant in their response patterns when assessing proton density–weighted images. There was very good agreement for disc morphology, cortical bone and bone structures/functions; however, there was wide variation for medullary bone marrow signs. T2-weighted imaging was found to be the best examination to assess the medullary bone. For evaluating of disc morphology, cortical bone and bone structures/functions, any protocol is indicated once the protocol does not interfere with the analysis312103109Almăşan, O.C., Hedeşiu, M., Băciuţ, G., Leucuţa, D.C., Băciuţ, M., Disk and joint morphology variations on coronal and sagittal MRI in temporomandibular joint disorders (2013) Clinical Oral Investigations, 17 (4), pp. 1243-1250. , http://dx.doi.org/10.1007/s00784-012-0803-4, PMid:22868824Brooks, S.L., Brand, J.W., Gibbs, S.J., Hollender, L., Lurie, A.G., Omnell, K.A., Westesson, P.L., White, S.C., Imaging of the temporomandibular joint: A position paper of the American Academy of Oral and Maxillofacial Radiology (1997) Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics, 83 (5), pp. 609-618. , PMid:9159823Cozzollino, F.A., Rapoport, A., Franzi, A.S., Souza, R.P., Pereirta, C.A.B., Dedivitis, R.A., Correlação entre os achados clínicos e imaginológicos nas disfunções temporomandibulares (2008) Radiologia Brasileira, 41 (1), pp. 13-17. , http://dx.doi.org/10.1590/S0100-39842008000100006Larheim, T.A., Westesson, P., Sano, T., Temporomandibular joint disk displacement: Comparison in asymptomatic volunteers and patients (2001) Radiology, 218 (2), pp. 428-432. , http://dx.doi.org/10.1148/radiology.218.2.r01fe11428, PMid:11161157Lopes, S.L., Costa, A.L., Cruz, A.D., Li, L.M., Almeida, S.M., Clinical and MRI investigation of temporomandibular joint in major depressed patients (2012) Dento Maxillo Facial Radiology, 41 (4), pp. 316-322. , http://dx.doi.org/10.1259/dmfr/27328352, PMid:22517997 PMCid:PMC3729006Manfredini, D., Bonnini, S., Stellini, E., Salmaso, L., Guarda-Nardini, L., Comparison of magnetic resonance imaging findings in temporomandibular joints of the two sides (2014) Clinical Oral Investigations, 18 (2), pp. 499-506. , http://dx.doi.org/10.1007/s00784-013-0984-5, PMid:23640716Sano, T., Yamamoto, M., Okano, T., Gokan, T., Westesson, P.L., Commom abnormalities in temporomandibular joint imaging (2004) Current Problems in Diagnostic Radiology, 33 (1), pp. 16-24. , http://dx.doi.org/10.1016/j.cpradiol.2003.09.001, PMid:14712198Schiffman, E.L., Truelove, E.L., Ohrbach, R., Anderson, G.C., John, M.T., List, T., Look, J.O., The research diagnostic criteria for temporomandibular disorders. I: Overview and methodology for assessment of validity (2010) Journal of Orofacial Pain, 24 (1), pp. 7-24. , PMid:20213028 PMCid:PMC3157055Sessle, B.J., A focus on the research diagnostic criteria for temporomandibular disorders (2009) Journal of Orofacial Pain, 23 (1), pp. 5-6. , PMid:19264031Styles, C., Whyte, A., MRI in the assessment of internal derangement and pain within the temporomandibular joint: A pictorial essay (2002) British Journal of Oral & Maxillofacial Surgery, 40 (3), pp. 220-228. , http://dx.doi.org/10.1054/bjom.2001.0757, PMid:12054713Tasaki, M.M., Westesson, P.L., Isberg, A.M., Ren, Y.F., Tallents, R.H., Classification and prevalence of temporomandibular joint disc displacement in patients and symptom-free volunteers (1996) American Journal of Orthodontics and Dentofacial Orthopedics, 109 (3), pp. 249-262. , http://dx.doi.org/10.1016/S0889-5406(96)70148-8Tasali, N., Cubuk, R., Aricak, M., Ozarar, M., Saydam, B., Nur, H., Tuncbilek, N., Temporomandibular joint (TMJ) pain revisited with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) (2012) European Journal of Radiology, 81 (3), pp. 603-608. , http://dx.doi.org/10.1016/j.ejrad.2011.01.044, PMid:21300493Wangsrimongkol, T., Manosudprasit, M., Pisek, P., Chowchuen, P., Chantaramungkorn, M., Temporomandibular joint growth adaptation and articular disc positional changes in functional orthopedic treatment: Magnetic resonance imaging investigation (2012) Journal of the Medical Association of Thailand, 95, pp. S106-S115. , PMid:2396162

Integer and half-integer flux-quantum transitions in a niobium/iron-pnictide loop

The recent discovery of iron-based superconductors challenges the existing paradigm of high-temperature superconductivity. Owing to their unusual multi-orbital band structure, magnetism, and electron correlation, theories propose a unique sign reversed s-wave pairing state, with the order parameter changing sign between the electron and hole Fermi pockets. However, because of the complex Fermi surface topology and material related issues, the predicted sign reversal remains unconfirmed. Here we report a novel phase-sensitive technique for probing unconventional pairing symmetry in the polycrystalline iron-pnictides. Through the observation of both integer and half-integer flux-quantum transitions in composite niobium/iron-pnictide loops, we provide the first phase-sensitive evidence of the sign change of the order parameter in NdFeAsO0.88F0.12, lending strong support for microscopic models predicting unconventional s-wave pairing symmetry. These findings have important implications on the mechanism of pnictide superconductivity, and lay the groundwork for future studies of new physics arising from the exotic order in the FeAs-based superconductors.Comment: 23 pages, including 4 figures and supplementary informatio