InsubriaSPACE - Thesis PhD Repository
http://insubriaspace.cineca.it:80
Il repository digitale InsubriaSPACE descrive, archivia, indizizza, preserva e distribuisce materiale di ricerca in forma digitale.2020-04-03T01:27:25ZEffect of blueberry supplementation in overweight and obese pregnant women
http://hdl.handle.net/10277/920
Titolo: Effect of blueberry supplementation in overweight and obese pregnant women
Autori: Pellegrini, Francesco Paolo
Abstract: Childhood obesity is a serious problem growing worldwide that needs to be early considered and treated. Maternal overweight and obesity lead to foetal complications and to an increased risk of child obesity. Blueberry bio-active compounds have antioxidant properties and improve insulin sensitivity in obese individuals. We proposed a daily integration of a freeze-dried blueberry extract in the last trimester of a population of overweight and obese pregnant women. Mother cytokine milieu, birth weight and at age one, were compared with a matched control group.
Results: birth weight was significantly lower in those whose mothers assumed the blueberry extract (male: 3636 gr ± 56,7 in control group and 3302 gr ± 60,9 in the blueberry, P=.001; female: 3446 gr ± 53 in control group and 3094 gr ± 65,5 in the blueberry, P <.0001) and this result remained comparable at age one (male control group: 9597 gr ± 134,4; blueberry: 8656 gr ± 271,9; P=.0021; female control group: 8812 ± 167,5; blueberry: 8083 ± 266,3; P=.0211); pro-inflammatory cytokines (TNF-α and leptin) were significantly reduced in the blueberry group (control 29,89 pg/mL ± 0,283 vs blueberry 8,124 ng/mL ± 0,1085 and 17,28 ± 0,4742 vs 6,977 ± 0,1187, respectively); anti-inflammatory cytokines (TGF-β and IL-4) were significantly increased in the blueberry group (control 4,196 pg/ml ± 0,9752 vs blueberry 14,87 pg/ml ± 0,8844 and 14,87 pg/ml ± 0,8844 vs 55,22 ± 1,47, respectively), CRP levels were significantly lower in the blueberry group (control 5,917 mg/L ± 0,698 vs blueberry 3,741 mg/L ± 0,6279).
Conclusion: a daily dietary supplementation with bioactive from whole blueberries in overweight and/or obese pregnant women is an effective intervention to reduce the risk of foetal macrosomia and early childhood obesity.2018-12-31T23:00:00ZDelay differential equations in a nonlinear cochlear model.
http://hdl.handle.net/10277/919
Titolo: Delay differential equations in a nonlinear cochlear model.
Autori: Botti, Teresa
Abstract: The human auditory system performs its primary function in the cochlea, the main organ of the inner ear, where the spectral analysis of a sound signal and its transduction into a neural signal occur. It is filled with liquid and divided in two cavities by the basilar membrane (BM). A sound stimulus propagates in air as an acoustic pressure wave through the outer and the middle ear. The pressure of the stapes on the oval window (boundary between the middle and the inner ear) causes the cochlear fluid to flow between the two cavities through a hole at the end of the BM. A spatial partial differential equation of fluid-dynamics describes this physical process. As a consequence of the differential pressure between the two cavities, each micro-element of the BM oscillates as a forced damped harmonic oscillator. The BM displacement is amplified by the overlying outer hair cells (OHCs) through a nonlinear nonlocal active feedback mechanism. The latter can be modeled by means of various representations. Among them, the delayed stiffness model of Talmadge et al. (J. Acoust. Soc. Am. 104, 1998) has been considered in this thesis. Specifically, the cochlear nonlinearity is introduced as a quadratic function of the BM displacement in the passive linear damping function. Moreover, the active mechanism is described by two additional forces, each one proportional to the BM displacement delayed by a slow and a fast feedback constant time, respectively. According to this model, a time delay differential equation (DDE) of the second order describes the oscillating dynamics of the BM. A different formulation of the nonlinear active mechanism, driven by the OHCs, is expressed as a nonlinear function of the BM velocity by the anti-damping model of Moleti et al. (J. Acoust. Soc. Am. 133, 2013). In this case the model equations do not contain time delays.
The numerical integration of the above mentioned models has been obtained by finite differencing with respect to the space variable in the state space, as introduced by Elliott et al. (J. Acoust. Soc. Am. 122, 2007), and then integrating in time with the adaptive package introduced by Bertaccini and Sisto as a modification of the popular Matlab ode15s package (J. Comput. Phys. 230, 2011). The semidiscrete formulation of the delayed stiffness model and the anti-damping model has a non trivial mass matrix, and eigenvalues of the system matrix with large negative real part and imaginary part. That is why an implicit solver with an infinite region of absolute stability should be used. Therefore, the customized Matlab ode15s package by Bertaccini and Sisto seems to be the convenient choice to integrate the problem at hand numerically. In particular, for the delayed stiffness model, an integrator for constant DDEs (the method of steps; Bellen and Zennaro, Oxford University Press 2003) has been formulated and based on the customized ode15s.
All these topics have been discussed in this doctoral thesis, which is subdivided in the following chapters.
Chapter 1 describes the anatomy of the human ear, with special regard to the cochlea. Some experimental evidences about the cochlear mechanisms are discussed, in order to support the cochlear modeling. Two physical models with one degree of freedom are shown: the anti-damping model of Sisto et al. (J. Acoust. Soc. Am. 128, 2010) and Moleti et al. (J. Acoust. Soc. Am. 133, 2013), and the delayed stiffness model of Talmadge et al. (J. Acoust. Soc. Am. 104, 1998).
Chapter 2 discusses the general theory of DDEs, with greater reference to constant and time dependent DDEs from Bellen and Zennaro (Oxford University Press 2003). Existence and uniqueness of time dependent DDEs are briefly analyzed, while the method of steps is shown as a basic approach to find a numerical approximation of the DDEs solution. According to this method, IVPs of constant DDEs (as for the semidiscrete delayed stiffness model) are turned into IVPs of ODEs in a subinterval (of length less than or equal to the time delay) of the whole integration interval. Each IVP of ODEs can be integrated by means of any ODEs numerical method, and its convergence is then discussed.
Chapter 3 describes the main tools used to find an approximate solution of the considered models. In particular, the discretization for spatial partial derivatives by means of finite differences is shown. Such a representation turns a model, which is continuous in the space-time domain, into a semidiscrete model to be integrated in time. The models considered in this thesis are stiff, so the phenomenon of stiffness is discussed and the ode15s package of Matlab for integrating stiff ODEs is described. Nevertheless, greater benefits can be obtained by using the ode15s package customized by Bertaccini and Sisto as a hybrid direct-iterative solver which exploits Krylov subspace methods.
Chapter 4 shows the semidiscrete formulation of the continuous models (anti-damping model and delayed stiffness model) in the state space with respect to the spatial variable, as introduced by Elliott et al. (J. Acoust. Soc. Am. 122, 2007). The algebraic properties of the semidiscrete models are discussed in order to show why the customized ode15s package may perform a faster numerical integration of the semidiscrete models and how this solver can be used in an integration numerical technique for constant DDEs (the method of steps).
Chapter 5 shows the results produced by the numerical experiments of the delayed stiffness model by supplying a sinusoidal tone, and compares them with the numerical results produced by the anti-damping model. Some considerations about the numerical approach of the time integration are also discussed, and a part of the simplified code used for integrating the semidiscrete delayed stiffness model, is reported. The results are comparable with those obtained by the anti-damping model, and then the numerical experimental evidences seem to justify the proposed integration technique for constant DDEs. Delayed model properties of tonotopicity, anti-damping and nonlinearity are verified, as well as the dependence of the approximate solution on some free parameters of the model. The cochlear response described by the delayed stiffness model shows a typical tall and broad BM activity pattern. This behavior is also found in the numerical results of a model with two degree of freedom produced by Neely and Kim (J. Acoust. Soc. Am. 79, 1986) and Elliott et al. (J. Acoust. Soc. Am. 122, 2007).2014-12-31T23:00:00ZMalattia trombotica: condizioni cliniche ad aumentato rischio e terapia anticoagulante
http://hdl.handle.net/10277/918
Titolo: Malattia trombotica: condizioni cliniche ad aumentato rischio e terapia anticoagulante
Autori: Romualdi, Erica
Abstract: missing2013-12-31T23:00:00ZA multi-scale study of fibrin gels formation: from the early phases to the final network.
http://hdl.handle.net/10277/917
Titolo: A multi-scale study of fibrin gels formation: from the early phases to the final network.
Autori: Molteni, Matteo
Abstract: Fibrin gel polymerization, key element of blood coagulation, produces the network inside which platelets and other blood components are trapped, forming the hemostatic plug that stops bleeding. As fully biocompatible materials with extraordinary mechanical properties, fibrin gels are ideal substrates for many biotechnological applications.
By studying the early phases of polymerization, using simultaneous Small Angle X-ray Scattering and Wide Angle Light Scattering, we defined a new polymerization model in which single-bonded "Y Ladder" polymers rapidly elongate before undergoing a delayed transition to the traditional double-stranded fibrils.
Completely formed fibrin gel appears as a fractal collection of straight fibers, almost monodisperse in diameter and connected together at nodal points with a branching order 3-4. Taking into account these features, we implemented a simple iterative algorithm able to generate in silico gels. The resulting 3D network resembles real fibrin gels and can be sketched as an assembly of densely packed fractal blobs. Using this model we refined the analytical expression of the form factor which is capable of accurately fitting the Light Scattering data, giving the gels' structural parameters.
By globally fitting Low Angle Elastic Light Scattering data with the refined form factor and Turbidimetry data with a function obtained by angularly integrating the scattering form factor, all the parameters characterizing the gel can be robustly recovered.
Finally we have also developed a 2D method for the determination of the gel pore size that analyze thin stacks of randomly sampled thresholded 3D confocal images.2015-12-31T23:00:00Z