565 research outputs found
Tannic acid is not mutagenic in germ cells but weakly genotoxic in somatic cells of Drosophila melanogaster
Tannic acid (TA) was tested for genotoxic activity in three different assays (1-3) in Drosophila melanogaster by feeding of larvae or adult flies. TA did not induce sex-linked recessive lethals (1) nor sex-chromosome loss, mosaicism or non-disjunction (2) in male germ cells. In the wing somatic mutation and recombination test (SMART) (3) TA was found to be toxic for larvae of the high bioactivation cross and produced a weak positive response. These results suggest that this compound, when administered orally to larvae or adults of D.melanogaster, is not mutagenic and clastogenic in male germ cells, but weakly genotoxic in somatic cells of the wing imaginal dis
Anatomical Features Of The Urethra And Urinary Bladder Catheterization In Female Mice And Rats. An Essential Translational Tool [características Anatômicas Da Cateterização Da Uretra E Bexiga De Camundongos E Ratos Fêmeas. Instrumento Essencial Na Pesquisa Pré Clínica]
PURPOSE: To present fundamental anatomical aspects and technical skills necessary to urethra and urinary bladder catheterization in female mice and rats. METHODS: Urethral and bladder catheterization has been widely utilized for carcinogenesis and cancer research and still remains very useful in several applications: from toxicological purposes as well as inflammatory and infectious conditions to functional aspects as bladder dynamics and vesicoureteral reflux, among many others. RESULTS: Animal models are in the center of translational research and those involving rodents are the most important nowadays due to several advantages including human reproducibility, easy handling and low cost. CONCLUSIONS: Although technical and anatomical pearls for rodent urethral and bladder access are presented as tackles to the advancement of lower urinary tract preclinical investigation in a broaden sight, restriction to female animals hampers the male microenvironment, demanding future advances.26SUPPL. 2106110Reis, L.O., Fávaro, W.J., Ferreira, U., Billis, A., Fazuoli, M.G., Cagnon, V.H., Evolution on experimental animal model for upper urothelium carcinogenesis (2010) World J Urol, 28, pp. 499-505Mulder, G.J., Scholtens, E., Meijer, D.K., Collection of metabolites in bile and urine from the rat (1981) Methods Enzymol, 77, pp. 21-30Krinke, G.J., (2000) The Laboratory Rat, , San Diego, CA: Academic PressPhillips, J.I., Davies, I., The comparative morphology of the bladder and urethra in young and old female C57BL/Icrfat mice (1980) Exp Geront, 15, pp. 551-562Andersson, K.E., Arner, A., Urinary bladder contraction and relaxation: Physiology and pathophysiology (2004) Physiol Rev, 84, pp. 935-986Reis, L.O., Pereira, T.C., Favaro, W.J., Cagnon, V.H., Lopes-Cendes, I., Ferreira, U., Experimental animal model and RNA interference: A promising association for bladder cancer research (2009) World J Urol, 27, pp. 353-361Marini, R.P., Esteves, M.I., Fox, J.G., A technique for catheterization of the urinary bladder in the ferret (1994) Lab Anim, 28, pp. 155-15
Hidden non-Fermi liquid behavior due to crystal field quartet
We study a realistic Kondo model for crystal field quartet ground states
having magnetic and non-magnetic (quadrupolar) exchange couplings with
conduction electrons, using the numerical renormalization group method. We
focus on a local effect dependent on singlet excited states coupled to the
quartet, which reduces the non-magnetic coupling significantly and drives
non-Fermi liquid behavior observed in the calculated quadrupolar
susceptibility. A crossover from the non-Fermi liquid state to the Fermi liquid
state is characterized by a small energy scale very sensitive to the
non-magnetic coupling. On the other hand, the Kondo temperature observed in the
magnetic susceptibility is less sensitive. The different crystal-field
dependence of the two exchange couplings may be related to the different
dependence of quadrupolar and magnetic ordering temperatures in
CeLaB.Comment: 7 pages, 5 EPS figures, REVTe
Order and nFl Behavior in UCu4Pd
We have studied the role of disorder in the non-Fermi liquid system UCu4Pd
using annealing as a control parameter. Measurement of the lattice parameter
indicates that this procedure increases the crystallographic order by
rearranging the Pd atoms from the 16e to the 4c sites. We find that the low
temperature properties depend strongly on annealing. Whereas the non-Fermi
liquid behavior in the specific heat can be observed over a larger temperature
range after annealing, the clear non-Fermi liquid behavior of the resistivity
of the unannealed sample below 10 K disappears. We come to the conclusion that
this argues against the Kondo disorder model as an explanation for the
non-Fermi liquid properties of both as-prepared and annealed UCu4Pd
Localized spin ordering in Kondo lattice models
Using a non-Abelian density matrix renormalization group method we determine
the phase diagram of the Kondo lattice model in one dimension, by directly
measuring the magnetization of the ground-state. This allowed us to discover a
second ferromagnetic phase missed in previous approaches. The phase transitions
are found to be continuous. The spin-spin correlation function is studied in
detail, and we determine in which regions the large and small Fermi surfaces
dominate. The importance of double-exchange ordering and its competition with
Kondo singlet formation is emphasized in understanding the complexity of the
model.Comment: Revtex, 4 pages, 4 eps figures embedde
Unified order-disorder vortex phase transition in high-Tc superconductors
The diversity of vortex melting and solid-solid transition lines measured in
different high-T superconductors is explained, postulating a unified
order-disorder phase transition driven by both thermally- and disorder-induced
fluctuations. The temperature dependence of the transition line and the nature
of the disordered phase (solid, liquid, or pinned liquid) are determined by the
relative contributions of these fluctuations and by the pinning mechanism. By
varying the pinning mechanism and the pinning strength one obtains a spectrum
of monotonic and non-monotonic transition lines similar to those measured in
BiSrCaCuO, YBaCuO,
NdCeCuO,
BiPbSrCaCuO and (LaSr)CuOComment: To be published in Phys. Rev. B Rapid Com
On the critical behavior of disordered quantum magnets: The relevance of rare regions
The effects of quenched disorder on the critical properties of itinerant
quantum antiferromagnets and ferromagnets are considered. Particular attention
is paid to locally ordered spatial regions that are formed in the presence of
quenched disorder even when the bulk system is still in the paramagnetic phase.
These rare regions or local moments are reflected in the existence of spatially
inhomogeneous saddle points of the Landau-Ginzburg-Wilson functional. We derive
an effective theory that takes into account small fluctuations around all of
these saddle points. The resulting free energy functional contains a new term
in addition to those obtained within the conventional perturbative approach,
and it comprises what would be considered non-perturbative effects within the
latter. A renormalization group analysis shows that in the case of
antiferromagnets, the previously found critical fixed point is unstable with
respect to this new term, and that no stable critical fixed point exists at
one-loop order. This is contrasted with the case of itinerant ferromagnets,
where we find that the previously found critical behavior is unaffected by the
rare regions due to an effective long-ranged interaction between the order
parameter fluctuations.Comment: 16 pp., REVTeX, epsf, 2 figs, final version as publishe
A new staggered algorithm for thermomechanical coupled problems
This study presents a new staggered coupled strategy to deal with thermomechanical problems. The proposed strategy is based on the isothermal split methodology, i.e. the mechanical problem is solved at constant temperature and the thermal problem is solved for a fixed configuration. Nevertheless, the procedure for this strategy is divided into two phases within each increment: the prediction and the correction phases, while the interchange of information is performed on both. This allows taking advantage of automatic time-step control techniques, previously implemented for the mechanical problem, which is the main feature that distinguishes it from the classical strategies. The aim of the proposed strategy is to reduce the computational cost without compromising the accuracy of the results. The new coupling strategy is validated using three numerical examples, comparing its accuracy and performance with the ones obtained with the classical (commonly employed) strategies for solving thermomechanical problems. Moreover, the influence of the time-step size on the accuracy is analysed. The results indicate that the proposed strategy presents accuracy close to the one obtained with the implicit coupling algorithm, while the computational cost is only slightly higher than the one required by the explicit strategy. (C) 2017 Elsevier Ltd. All rights reserved.The authors gratefully acknowledge the financial support of the Portuguese Foundation for Science and Technology (FCT) under projects P2020-PTDC/EMS-TEC/0702/2014 (POCI-01-0145-FEDER-016779) and P2020-PTDC/EMS-TEC/6400/2014 (POCI-01-0145-FEDER-016876) by UE/FEDER through the program COMPETE 2020. The second author is also grateful to the FCT for the Postdoctoral grant SFRH/BPD/101334/2014.info:eu-repo/semantics/publishedVersio
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