163,397 research outputs found
Sensory neurons : stem cells and development
No full textThe sensory nervous system is the only means we have of communicating with the surrounding world. The neurons responsible for the sensation of pain, touch, the ability to know the position of our limbs and part of maintenance of body posture are located in the dorsal root ganglia (DRG). Stem cell biology has, during the recent years greatly enhanced our understanding of developmental processes. The aim of this thesis was to isolate and characterize stem cells from the sensory nervous system and to study the development of functional neuronal subtypes.In the work presented 1 show the identification of a neural crest stem cell (NCSC) that is located in the boundary cap (BC). The BC is a transient structure present during embryogenesis lining the boundary between the peripheral and central nervous system at the exit/entry zone of sensory and motor efferents. This multipotent stem cell is unique as compared to previously described NCSCs, in its ability to form sensory neurons in vitro. The sensory neurons are functionally active as assayed by calcium imaging using temperature stimuli and sensory specific transient receptor potential (TRP)-channel ligands.I further show that the boundary cap neural crest stem cell (bNCSC) can give rise to Schwann cells that myclinate regenerating axons in vivo, suggesting a possibility for the use of these stem cells for regenerative therapy. The bNCSC express the well described stem cell marker, stage specific antigen 1 (SSEA-1) as well as proteins involved in the production of gamma amino butyric acid (GABA). Furthermore, GABA drastically reduces the proliferation of bNCSC, in a pathway independent of intracellular signalling. Antagonizing endogenous production using GABAA receptor antagonist bicuculline increases the same. This suggests GABA as a signal to regulate proliferation in the BC stem cell niche and thus providing the basis for a possible increase of production in response to an injury.In the last part of the thesis 1 describe and define the developmental emergence of different subtypes of developing sensory neurons based on functional responses to capsaicin, menthol, and cinnamon aldehyde, agonists to TRPV1, TRPM8 and TRPA 1 respectively.List of scientific papersI. Hjerling-Leffler J, Marmigere F, Heglind M, Cederberg A, Koltzenburg M, Enerback S, Ernfors P (2005). The boundary cap: a source of neural crest stem cells that generate multiple sensory neuron subtypes. Development. 132(11): 2623-32. Epub 2005 May 4 https://pubmed.ncbi.nlm.nih.gov/15872002II. Aquino JB, Hjerling-Leffler J, Koltzenburg M, Edlund T, Villar MJ, Ernfors P (2006). In vitro and in vivo differentiation of boundary cap neural crest stem cells into mature Schwann cells. Exp Neurol. Jan 24: Epub ahead of print. https://pubmed.ncbi.nlm.nih.gov/16442526III. Hjerling-Leffler J, Andang M, Catelo-Branco G, Koltzenburg M, Ernfors P (2006). GABA negatively controls proliferation in the boundary cap stem cell niche. [Manuscript]IV. Hjerling-Leffler J, Al-Qatari M, Ernfors P, Koltzenburg M (2006). Emergance of functional sensory subtypes as indentified by TRP-channle expression. [Manuscript]</p
Sobre as funções Mittag-Leffler e o modelo fracionário de materiais viscoelásticos
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Mecânica.Materiais viscoelásticos são hoje largamente aplicados em vários ramos da engenharia, com destaque para a mecânica e aeroespacial. Uma das razões para tal popularidade reside na facilidade com que os materiais viscoelásticos são vulcanizados nas mais diferentes formas. Outra, é o fato de que inúmeros materiais básicos podem ter suas propriedades dinâmicas adequadas, mediante introdução de aditivos, às várias aplicações específicas. O Grupo PISA-LVA os vem estudando, bem como suas aplicações, há cerca de quinze anos, tendo já granjeado reputação internacional. Dentre as suas conquistas, cite-se, por importante no presente trabalho, o desenvolvimento de técnica para a identificação dos parâmetros do modelo fracionário dos materiais viscoelásticos. Esta técnica, já difundida internacionalmente, acabou por substituir, no âmbito do Grupo, com enormes vantagens, a da norma ASTM E 756 98. Esta técnica é toda estabelecida no domínio da freqüência. Surge naturalmente a questão: se esses parâmetros representam o material viscoelástico com excelente precisão, não seria correto utilizá-los para o cômputo de propriedades importantes, definidas no domínio do tempo, como creep, compression set e outras? Este trabalho pretende ser um passo inicial para responder a essas questões, entre outras. Revê os modelos de Maxell, Kelvin-Voigt e Linear Padrão (ou Zener), primeiro na forma clássica, a derivadas inteiras. Repete-se este estudo, agora permitindo que as derivadas tenham ordem fracionária. As equações resultantes são tratadas pela via da Transformada de Laplace. As soluções das equações resultantes envolvem as funções de Mittag-Leffler, notórias pelas dificuldades computacionais que apresentam, em certas circunstâncias. Embora inúmeros estudos e algoritmos tenham vindo recentemente à luz, parece, entretanto, que um algoritmo absolutamente robusto, infenso a toda e qualquer circunstância, ainda está para ser escrito. Como a função de creep é bem comportada para o computo numérico, procura-se calcular a função de relaxação de tensão por deconvolução. Uma outra saída, também aqui apresentada, é a da inversão numérica da transformada de Laplace. Os resultados dessas técnicas são cotejados com aqueles obtidos pelo cômputo direto da função de Mittag-Leffler, em casos em que há convergência
Emergence of functional sensory subtypes as defined by transient receptor potential channel expression
No full textThe existence of heterogeneous populations of dorsal root ganglion (DRG) neurons conveying different somatosensory information is the basis for the perception of touch, temperature, and pain. A differential expression of transient receptor potential (TRP) cation channels contributes to this functional heterogeneity. However, little is known about the development of functionally diverse neuronal subpopulations. Here, we use calcium imaging of acutely dissociated mouse sensory neurons and quantitative reverse transcription PCR to show that TRP cation channels emerge in waves, with the diversification of functional groups starting at embryonic day 12.5 (E12.5) and extending well into the postnatal life. Functional responses of voltage-gated calcium channels were present in DRG neurons at E11.5 and reached adult levels by E14.5. Responses to capsaicin, menthol, and cinnamaldehyde were first seen at E12.5, E16.5, and postnatal day 0 (P0), when the mRNA for TRP cation channel, subfamily V, member 1 (TRPV1), TRP cation channel, subfamily M, member 8 (TRPM8), and TRP cation channel, subfamily A, member 1 (TRPA1), respectively, was first detected. Cold-sensitive neurons were present before the expression or functional responses of TRPM8 or TRPA1. Our data support a lineage relationship in which TRPM8- and TRPA1-expressing sensory neurons derive from the population of TRPV1-expressing neurons. The TRPA1 subpopulation of neurons emerges independently in two distinct classes of nociceptors: around birth in the peptidergic population and after P14 in the nonpeptidergic class. This indicates that neurons with similar receptive properties can be generated in different sublineages at different developmental stages. This study describes for the first time the emergence of functional subtypes of sensory neurons, providing new insight into the development of nociception and thermoreception
Laplace transform and the Mittag-Leffler function
No full textCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORThe exponential function is solution of a linear differential equation with constant coefficients, and the Mittag-Leffler function is solution of a fractional linear differential equation with constant coefficients. Using infinite series and Laplace transform, we introduce the Mittag-Leffler function as a generalization of the exponential function. Particular cases are recovered. © 2013 Taylor & Francis.The exponential function is solution of a linear differential equation with constant coefficients, and the Mittag-Leffler function is solution of a fractional linear differential equation with constant coefficients. Using infinite series and Laplace transform, we introduce the Mittag-Leffler function as a generalization of the exponential function. Particular cases are recovered454595604CAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORsem informaçãoAblowitz, M.J., Fokas, A.S., (1999) Complex variables: Introduction and applications (Cambridge texts in applied mathematics), , Cambridge (UK),: Cambridge University PressSneddon, I.N., (1995) Fourier transforms, , New York (NY),: Dover Publications IncCoddington, E.A., (1989) An introduction to ordinary differential equations, , New York (NY),: Dover Publications IncKevorkian, J., (1990) Partial differential equations, analytical solution techniques, , Belmont (CA),: Wadsworth & Brooks/Cole Advanced Book & SoftwareCamargo, R.F., Chiacchio, A.O., Oliveira, E.C., One-sided and two-sided Green's function (2013) Bound Value Probl, 2013, p. 45Miller, K.S., Ross, B., (1993) An introduction to the fractional calculus and fractional differential equations, , New York (NY),: WileyMittag-Leffler, G.M., A generalization of the Laplace-Abel integral (1903) C R Acad Sci Paris, 137, pp. 537-539Prabhakar, T.R., A singular integral equation with generalized Mittag-Leffler function in the kernel (1971) Yokohama Math J, 19, pp. 7-15Mainardi, F., (2010) Fractional calculus and waves in linear viscoelasticity, , London,: Imperial College PressCapelas de Oliveira, E., (2012) Special functions and applications, , 2nd, São Paulo,: Livraria Editora da Física, PortugueseMathai, A.M., Haubold, H.J., (2008) Special functions for applied scientists, , New York (NY),: Springer ScienceOliveira, E.C., Rodrigues Jr., W.A., (2006) Analytical functions and applications, , São Paulo,: Livraria Editora da Física, PortugueseMittag-Leffler, G.M., On the new function Eα(x) (1903) C R Acad Sci Paris, 137, pp. 554-558Humbert, P., Agarwal, R.P., On the Mittag-Leffler function and some of its generalizations (1953) Bull Sci Math Ser, 77, pp. 180-185Shukla, A.K., Prajapati, J.C., On a generalization of Mittag-Leffler function and its properties (2007) J Math Anal Appl, 336, pp. 797-811Gehlot, K.S., The generalized k-Mittag-Leffler function (2012) Int J Contemp Math Sci, 7, pp. 2213-2219Silva Costa, F., (2011) Fox's H function and applications, , Campinas: Unicamp, Portugues
Flat Mittag-Leffler modules over countable rings
No full textWe show that over any ring, the double Ext-orthogonal class to all flat Mittag-Leffler modules contains all countable direct limits of flat Mittag-Leffler modules. If the ring is countable, then the double orthogonal class consists precisely of all flat modules, and we deduce, using a recent result of Saroch and Trlifaj, that the class of flat Mittag-Leffler modules is not precovering
in Mod -R unless R is right perfect
\u3cem\u3eJews and Mormons: Two Houses of Israel\u3c/em\u3e Frank J. Johnson and Rabbi William J. Leffler
No full textFrank J. Johnson and Rabbi William J. Leffler. Jews and Mormons: Two Houses of Israel. Hoboken, New York: Ktav Publishing, 2000
[Report to Chief J. E. Curry, by an unknown author #1]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
[Report to Chief J. E. Curry, by an unknown author #2]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
Mittag‐Leffler state estimator design and synchronization analysis for fractional‐order BAM neural networks with time delays
No full textThis paper deals with the extended design of Mittag-Leffler state estimator and adaptive synchronization for fractional order BAM neural networks (FBNNs) with time delays. By the aid of Lyapunov direct approach and Razumikhin-type method a suitable fractional order Lyapunov functional is constructed and a new set of novel sufficient condition are derived to estimate the neuron states via available output measurements such that the ensuring estimator error system is globally Mittag-Leffler stable. Then, the adaptive feedback control rule is designed, under which the considered FBNNs can achieve Mittag-Leffler adaptive synchronization by means of some fractional order inequality techniques. Moreover, the adaptive feedback control may be utilized even when there is no ideal information from the system parameters. Finally, two numerical simulations are given to reveal the effectiveness of the theoretical consequences
Mittag-Leffler Functions and the Truncated V-fractional Derivative
No full textIn this paper, we introduce a new type of fractional derivative, which we called truncated V-fractional derivative, for α-differentiable functions, by means of the six-parameter truncated Mittag–Leffler function. One remarkable characteristic of this new derivative is that it generalizes several different fractional derivatives, recently introduced: conformable fractional derivative, alternative fractional derivative, truncated alternative fractional derivative, M-fractional derivative and truncated M-fractional derivative. This new truncated V-fractional derivative satisfies several important properties of the classical derivatives of integer order calculus: linearity, product rule, quotient rule, function composition and the chain rule. Also, as in the case of the Caputo derivative, the derivative of a constant is zero. Since the six parameters Mittag–Leffler function is a generalization of Mittag–Leffler functions of one, two, three, four and five parameters, we were able to extend some of the classical results of the integer-order calculus, namely: Rolle’s theorem, the mean value theorem and its extension. In addition, we present a theorem on the law of exponents for derivatives and as an application we calculate the truncated V-fractional derivative of the two-parameter Mittag–Leffler function. Finally, we present the V-fractional integral from which, as a natural consequence, new results appear as applications. Specifically, we generalize the inverse property, the fundamental theorem of calculus, a theorem associated with classical integration by parts, and the mean value theorem for integrals. We also calculate the V-fractional integral of the two-parameter Mittag–Leffler function. Further, we were able to establish the relation between the truncated V-fractional derivative and the truncated V-fractional integral and the fractional derivative and fractional integral in the Riemann–Liouville sense when the order parameter α lies between 0 and 1 (0 < α < 1)14622
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