Ontological Problem-Solving Framework for Assigning Sensor Systems and Algorithms to High-Level Missions

The lack of knowledge models to represent sensor systems, algorithms, and missions makes opportunistically discovering a synthesis of systems and algorithms that can satisfy high-level mission specifications impractical. A novel ontological problem-solving framework has been designed that leverages knowledge models describing sensors, algorithms, and high-level missions to facilitate automated inference of assigning systems to subtasks that may satisfy a given mission specification. To demonstrate the efficacy of the ontological problem-solving architecture, a family of persistence surveillance sensor systems and algorithms has been instantiated in a prototype environment to demonstrate the assignment of systems to subtasks of high-level missions

Non equilibrium phase transitions and Floquet Kibble-Zurek scaling

We study the slow crossing of non-equilibrium quantum phase transitions in periodically-driven systems. We explicitly consider a spin chain with a uniform time-dependent magnetic field and focus on the Floquet state that is adiabatically connected to the ground state of the static model. We find that this {\it Floquet ground state} undergoes a series of quantum phase transitions characterized by a non-trivial topology. To dinamically probe these transitions, we propose to start with a large driving frequency and slowly decrease it as a function of time. Combining analytical and numerical methods, we uncover a Kibble-Zurek scaling that persists in the presence of moderate interactions. This scaling can be used to experimentally demonstrate non-equilibrium transitions that cannot be otherwise observed.Comment: 7 pages, 3 figures, Supplemental Material. (In this last version, the one published in EPL, we provide a better discussion of the Floquet adiabatic theorem, the construction of the Floquet ground state as an adiabatic continuation and the nature of the phase transitions.

Ontological Problem-Solving Framework for Dynamically Configuring Sensor Systems and Algorithms

The deployment of ubiquitous sensor systems and algorithms has led to many challenges, such as matching sensor systems to compatible algorithms which are capable of satisfying a task. Compounding the challenges is the lack of the requisite knowledge models needed to discover sensors and algorithms and to subsequently integrate their capabilities to satisfy a specific task. A novel ontological problem-solving framework has been designed to match sensors to compatible algorithms to form synthesized systems, which are capable of satisfying a task and then assigning the synthesized systems to high-level missions. The approach designed for the ontological problem-solving framework has been instantiated in the context of a persistence surveillance prototype environment, which includes profiling sensor systems and algorithms to demonstrate proof-of-concept principles. Even though the problem-solving approach was instantiated with profiling sensor systems and algorithms, the ontological framework may be useful with other heterogeneous sensing-system environments

Floquet time crystal in the Lipkin-Meshkov-Glick model

In this work we discuss the existence of time-translation symmetry breaking in a kicked infinite-range-interacting clean spin system described by the Lipkin-Meshkov-Glick model. This Floquet time crystal is robust under perturbations of the kicking protocol, its existence being intimately linked to the underlying $\mathbb{Z}_2$ symmetry breaking of the time-independent model. We show that the model being infinite-range and having an extensive amount of symmetry breaking eigenstates is essential for having the time-crystal behaviour. In particular we discuss the properties of the Floquet spectrum, and show the existence of doublets of Floquet states which are respectively even and odd superposition of symmetry broken states and have quasi-energies differing of half the driving frequencies, a key essence of Floquet time crystals. Remarkably, the stability of the time-crystal phase can be directly analysed in the limit of infinite size, discussing the properties of the corresponding classical phase space. Through a detailed analysis of the robustness of the time crystal to various perturbations we are able to map the corresponding phase diagram. We finally discuss the possibility of an experimental implementation by means of trapped ions.Comment: 14 pages, 12 figure

Design of Small Molecules with Antitumor Activity through Computational Methodologies

Today, there are multiple targeted therapies against cancer. The most relevant ones are those aimed at the stop of cancer cells from growing, or at the halting of signals that stimulate blood vessels, or at helping the immune system destroy cancer cells, and many others. The last one, has achieved impressive results to date. Indeed, the immuno- oncology field is entering a new, exciting phase having the potential to change the current cancer treatment either as a standalone therapy or in combination. Recently, many innovative strategies exist to overcome tumor-induced immunosuppression. Currently the main ones are checkpoint blockade inhibitors, adoptive T cell transfers, and vaccination strategies. To date, the immuno-oncology therapeutics on the market are mostly biologic products (e.g. monoclonal antibodies (mAbs), proteins, engineered cells, and oncolytic viruses). However, for example, antibodies have specific drawbacks: high production costs, lack of oral bioavailability, poor tumor penetrating capacity, Fc-related toxicities, and immunogenic properties. In this perspective, small molecules could potentially overcome many of these issues and be complementary to, and potentially synergistic with, biologic therapeutics too. In this context, my PhD work was focused on discovery of small molecules targeting three different proteins: MDM2 (Mouse Double Minute 2) the PD-1/PD-L1 axis (Programmed cell Death protein-1/ Programmed Death-ligand 1), and STING protein (STimulator of INterferon Genes). For all targets, a tandem approach of computational studies/NMR spectroscopy was applied

Dissipation assisted Thouless pumping in the Rice-Mele model

We investigate the effect of dissipation from a thermal environment on topological pumping in the periodically-driven Rice-Mele model. We report that dissipation can improve the robustness of pumping quantisation in a regime of finite driving frequencies. Specifically, in this regime, a low-temperature dissipative dynamics can lead to a pumped charge that is much closer to the Thouless quantised value, compared to a coherent evolution. We understand this effect in the Floquet framework: dissipation increases the population of a Floquet band which shows a topological winding, where pumping is essentially quantised. This finding is a step towards understanding a potentially very useful resource to exploit in experiments, where dissipation effects are unavoidable. We consider small couplings with the environment and we use a Bloch-Redfield quantum master equation approach for our numerics: Comparing these results with an exact MPS numerical treatment we find that the quantum master equation works very well also at low temperature, a quite remarkable fact.Comment: 21 pages, 8 figure

Food Insecurity among Transgender and Gender Non-conforming People in the Southeast United States

Food insecurity in the United States (U.S.) has been identified as a pressing public health problem, as it contributes to hunger, obesity, chronic disease, and poor overall health. Despite increased national attention to addressing issues of food insecurity in the general population, nearly nothing is known about food insecurity in the transgender and gender non-conforming (TGNC) community. National population-based surveys do not include information on gender identity, rendering this population nearly invisible to public health professionals. Data from my dissertation sought to uncover and address issues of food insecurity in this otherwise “hidden” population. In Chapter II, qualitative interviews were conducted with 20 food insecure TGNC people living in the Southeast U.S. In this study, I found that participants were suffering from severe food insecurity and poverty. Study participants reporting facing multi-level discrimination that contributed to their food insecurity. In Chapter III, I documented the use of Facebook as a recruitment strategy for TGNC people. Results suggested that the use of targeted Facebook advertisements can be successful, however, gender-based digital harassment to potential study participants was also witnessed. Detailed protocol must be followed to minimize risk when recruiting highly-stigmatized populations. In Chapter IV, I further investigated issues of food insecurity, minority stress, community resilience, and the use of local food pantries by TGNC people living in the Southeast U.S. through an online, cross-sectional survey. Results indicated that many survey participants were food insecure (80.5%), few utilized Federal (19%) and local (22%) food assistance resources, and minority stress and community resilience were present. Minority stress indices were not related to food insecurity or the use of local food pantries. However, community resilience measures were related to the use of local food pantries.This dissertation informs a significant public health problem in a population at high risk for food insecurity. Chapters II and IV inform public health practitioners and the general public about food insecurity and the use of local food assistance resources among TGNC people. Chapter III provides critical guidance for researchers using targeted Facebook advertisements as a recruitment strategy for highly-stigmatized populations

Pattern formation and period doublings in the many-body coupled logistic maps

In this work we consider two many-body generalizations of the logistic map, where we couple single maps with nearest-neighbour interactions on a one-dimensional lattice, getting a discrete-time nonlinear dynamical system. Numerically looking at some period $2^k$-tupling order parameters, we check that at least for $k\in\{1,\,2,\,3,\,4\}$ the period-doubling transitions of the single map persist. The values of the driving parameter $\mu$ where they occur remain unchanged, independently of the system size, and of the type and the strength of the coupling in the many-body system. We numerically observe that the nonlinear dynamics leads to the formation of patterns, that can occur if $\mu$ lies beyond the first period-doubling threshold $\mu_2=3$ and appear if the system is large enough to accommodate them. We study the properties of the patterns -- the characteristic length scale and the amplitude -- and find that the former changes over many orders of magnitude when $\mu$ is varied. If the system size is large enough, the properties of the pattern have no relation at all with the single logistic map, witnessing the qualitative difference of the many-body dynamics from the single-map one. We discuss also the effect of noise and the relation of our findings with time crystals.Comment: 9 pages, 3 figure

Periodic driving of a coherent quantum many body system and relaxation to the Floquet diagonal ensemble

The coherent dynamics of many body quantum system is nowadays an experimental reality: by means of the cold atoms in optical lattices, many Hamiltonians and time-dependent perturbations can be engineered. In this Thesis we discuss what happens in these systems when a periodic perturbation is applied. Thanks to Floquet theory, we can see that -- if the Floquet spectrum obeys certain continuity conditions possible in the thermodynamic limit-- dephasing among Floquet quasi-energies makes local observables relax to a periodic steady regime described by an effective density matrix: the Floquet diagonal ensemble (FDE). By means of numerical examples on the Quantum Ising Chain and the Lipkin model, we discuss the properties of the FDE focusing on the difference among ergodic and regular quantum dynamics and on how this reflects on the thermal properties ($T=\infty$) of the asymptotic condition. We verify thermalization in the classically ergodic Lipkin model and we demonstrate that this effect is induced by the Floquet states being delocalized and obeying Eigenstate Thermalization Hypothesis.We discuss also, in the Ising chain case, the work probability distribution, whose asymptotic condition is not described by the form (Generalized Gibbs Ensemble) that FDE acquires for local obserbvables because of integrability. Dephasing makes some correlations invisible in the local observables, but they are still present in the system. We consider also the linear response limit: when the amplitude of the perturbation is vanishingly small, the Floquet diagonal ensemble is not sufficient to describe the asymptotic condition given by LRT. For every small but finite amplitude, there are quasi-degeneracies in the Floquet spectrum giving rise to pre-relaxation to the condition predicted by Linear Response; these phenomena are strictly related to energy absorption and boundedness of the spectrum