Probing the luminal microenvironment of reconstituted epithelial microtissues.

Polymeric microparticles can serve as carriers or sensors to instruct or characterize tissue biology. However, incorporating microparticles into tissues for in vitro assays remains a challenge. We exploit three-dimensional cell-patterning technologies and directed epithelial self-organization to deliver microparticles to the lumen of reconstituted human intestinal microtissues. We also develop a novel pH-sensitive microsensor that can measure the luminal pH of reconstituted epithelial microtissues. These studies offer a novel approach for investigating luminal microenvironments and drug-delivery across epithelial barriers

Photon path length distribution in random media from spectral speckle intensity correlations

We show that the spectral speckle intensity correlation (SSIC) technique can be profitably exploited to recover the path length distribution of photons scattered in a random turbid medium. We applied SSIC to the study of Teflon slabs of different thicknesses and were able to recover, via the use of the photon diffusion approximation theory, the characteristic transport mean free path ℓ∗ and absorption length s a of the medium. These results were compared and validated by means of complementary measurements performed on the same samples with standard pulsed laser time of flight technique

Trajectory optimization and optimal guidance in the restricted three-body problem

LAUREA MAGISTRALEIn questa tesi è stato sviluppato un algoritmo in grado di calcolare traiettorie per veicoli spaziali a bassa spinta nel problema dei tre corpi ristretto. Le basi matematiche utilizzate per trovare la legge di controllo ottima, che risolve il problema di ottimizzazione, risiedono nel calcolo alle variazioni e nel Principio di Massimo di Pontryagin. Tecniche omotopiche sono inoltre state implementate per facilitare il calcolo di traiettorie complesse, partendo da soluzioni più semplici. Per assicurare una maggiore robustezza delle traiettorie calcolate, è stato condotto uno studio di Neighbouring Optimal Guidance, analizzando l'impatto di perturbazioni sulla traiettoria nominale e implementando strategie correttive. L'algoritmo usato per ottenere questi risultati è stato sviluppato in MATLAB, sfruttando i più recenti strumenti messi a disposizione nel programma di calcolo, in modo da fornire alta precisione numerica e al contempo flessibilità nell'esplorazione di scenari con diverse traiettorie.In this thesis an algorithm capable of computing optimal trajectories for low-thrust spacecraft in the restricted three-body problem has been developed. The mathematical formulations exploited to find the optimal control law that solves the optimization problem involve calculus of variations and Pontryagin's Maximum Principle. Homotopy techniques are also implemented to facilitate the computation of complex trajectories, starting from simpler solutions. To ensure trajectory robustness, a neighboring optimal guidance study is conducted, analyzing the impact of perturbations on the nominal trajectories and implementing corrective strategies. The algorithm used to achieve these results has been developed in MATLAB, leveraging the most recent tools available in this software, providing both high numerical precision and flexibility in exploring different trajectory scenarios

A strategy for tissue self-organization that is robust to cellular heterogeneity and plasticity

Developing tissues contain motile populations of cells that can self-organize into spatially ordered tissues based on differences in their interfacial surface energies. However, it is unclear how self-organization by this mechanism remains robust when interfacial energies become heterogeneous in either time or space. The ducts and acini of the human mammary gland are prototypical heterogeneous and dynamic tissues comprising two concentrically arranged cell types. To investigate the consequences of cellular heterogeneity and plasticity on cell positioning in the mammary gland, we reconstituted its self-organization from aggregates of primary cells in vitro. We find that self-organization is dominated by the interfacial energy of the tissue–ECM boundary, rather than by differential homo- and heterotypic energies of cell–cell interaction. Surprisingly, interactions with the tissue–ECM boundary are binary, in that only one cell type interacts appreciably with the boundary. Using mathematical modeling and cell-type-specific knockdown of key regulators of cell–cell cohesion, we show that this strategy of self-organization is robust to severe perturbations affecting cell–cell contact formation. We also find that this mechanism of self-organization is conserved in the human prostate. Therefore, a binary interfacial interaction with the tissue boundary provides a flexible and generalizable strategy for forming and maintaining the structure of two-component tissues that exhibit abundant heterogeneity and plasticity. Our model also predicts that mutations affecting binary cell–ECM interactions are catastrophic and could contribute to loss of tissue architecture in diseases such as breast cancer

Laser spectroscopy of La- and anion trapping with a view to laser cooling

Direct laser cooling of negative ions has not yet been achieved. An important potential application of this technique is the use of cooled negative ions to sympathetically cool antiprotons. Antihydrogen, synthesized from cold antiprotons, is suitable for fundamental studies tests of CPT symmetry and the weak equivalence principle with antimatter. During this work, the negative lanthanum ion was identified as a good candidate for laser cooling using in-flight spectroscopy. Lanthanum anions were produced as a beam with a kinetic energy of a few keV and were excited using a tunable laser. The light radiation was superimposed to the ions both in a collinear and in a transverse setup to study the laser cooling transition. Trapping of anions both in a Penning trap and in a Paul trap was demonstrated as a prerequisite to increase the interaction time of anions and light towards the first realization of laser cooling. Detailed studies were performed both traps to find the best conditions for anions capture. All trap parameters were optimized with a view to a high capture efficiency as well as optimal properties of the confined plasma

From soft sediment deformation to fluid assisted faulting in the shallow part of a subduction megathrust analogue: the Sestola Vidiciatico tectonic Unit (Northern Apennines, Italy)

The Sestola Vidiciatico tectonic Unit (SVU) accommodated the early Miocene convergence between the subducting Adriatic plate and the overriding Ligurian prism, and has been interpreted as a field analogue for the shallow portion of subduction megathrusts. The SVU incorporated sediments shortly after their deposition and was active down to burial depth corresponding to temperatures around 150 \ub0C. Here, we describe the internal architecture of the basal thrust fault of the SVU through a multi-scale structural analysis and investigate the evolution of the deformation mechanisms with increasing burial depth. At shallow depth, the thrust developed in poorly lithified sediments which deformed by particulate flow. With increasing depth and lithification of sediments, deformation was accommodated in a meter scale, heterogeneous fault zone, including multiple strands of crack-and-seal shear veins, associated with minor distributed shearing in clay-rich domains and pressure solution. In the last stage, slip localized along a sharp, 20 cm thick shear vein, deactivating the fault zone towards the footwall. The widespread formation of crack-and-seal shear veins since the first stages of lithification indicates that failure along the thrust occurred at high fluid pressure and low differential stress already at shallow depth. Progressive shear localization occurs in the last phases of deformation, at temperatures typical of the transition to the seismogenic zone in active megathrusts

Opportunities for organoids as new models of aging.

The biology of aging is challenging to study, particularly in humans. As a result, model organisms are used to approximate the physiological context of aging in humans. However, the best model organisms remain expensive and time-consuming to use. More importantly, they may not reflect directly on the process of aging in people. Human cell culture provides an alternative, but many functional signs of aging occur at the level of tissues rather than cells and are therefore not readily apparent in traditional cell culture models. Organoids have the potential to effectively balance between the strengths and weaknesses of traditional models of aging. They have sufficient complexity to capture relevant signs of aging at the molecular, cellular, and tissue levels, while presenting an experimentally tractable alternative to animal studies. Organoid systems have been developed to model many human tissues and diseases. Here we provide a perspective on the potential for organoids to serve as models for aging and describe how current organoid techniques could be applied to aging research

Síndrome de boca ardiente: claves diagnósticas y terapéuticas

El síndrome de boca ardiente (SBA) se conoce también como boca escaldada, ardor bucal, glosodinia, glosopirosis, estomatodinia, estomatopirosis o disestesia oral. Se caracteriza por dolor o sensación de ardor, escozor o picazón, a veces aspereza, sobre todo en la lengua, paladar duro y labio inferior, en ausencia de datos clínicos o de laboratorio que justifiquen estos síntomas. Puede acompañarse de disgeusia (trastornos del gusto) y de xerostomía (boca seca), constituyendo la tríada clásica. Su etiología, poco precisa, es multifactorial. La evolución del cuadro tiende a ser crónica, alternando períodos de exacerbación y mejoría durante meses o años. Es más frecuente en mujeres perimenopáusicas o posmenopáusicas. Los episodios de SBA aparecen de forma espontánea y presentan un abanico variable en la gravedad de los síntomas. Mientras algunos pacientes refieren malestar leve o moderado, otros manifiestan dolor insoportable. Los síntomas suelen ser menos intensos..