Fernanda Pinheiro

Bio: Fernanda Pinheiro is an academic researcher from University of Cologne. The author has contributed to research in topics: Mott insulator & Boson. The author has an hindex of 6, co-authored 28 publications receiving 135 citations. Previous affiliations of Fernanda Pinheiro include Stockholm University & University of São Paulo.

XYZ Quantum Heisenberg Models with p-Orbital Bosons

Abstract: We demonstrate how the spin-1/2 XYZ quantum Heisenberg model can be realized with bosonic atoms loaded in the p band of an optical lattice in the Mott regime. The combination of Bose statistics and the symmetry of the p-orbital wave functions leads to a nonintegrable Heisenberg model with antiferromagnetic couplings. Moreover, the sign and relative strength of the couplings characterizing the model are shown to be experimentally tunable. We display the rich phase diagram in the one-dimensional case and discuss finite size effects relevant for trapped systems. Finally, experimental issues related to preparation, manipulation, detection, and imperfections are considered.

Confined p-band Bose-Einstein condensates

Abstract: We study bosonic atoms on the p-band of a two dimensional optical square lattice in the presence of a confining trapping potential. Using a mean-field approach, we show how the anisotropic tunneling for p-band particles affects the cloud of condensed atoms by characterizing the ground state density and the coherence properties of the atomic states both between sites and atomic flavors. In contrast to the usual results based on the LDA, the atomic density can become anisotropic. This anisotropic effect is especially pronounced in the limit of weak atom-atom interactions and of weak lattice amplitudes, i.e. when the properties of the ground state are mainly driven by the kinetic energies. We also investigate how the trap influences known properties of the non-trapped case. In particular, we focus on the behavior of the anti-ferromagnetic vortex-antivortex order, which for the confined system, is shown to disappear at the edges of the condensed cloud.

Adaptive evolution of hybrid bacteria by horizontal gene transfer

Abstract: Horizontal gene transfer is an important factor in bacterial evolution that can act across species boundaries. Yet, we know little about rate and genomic targets of cross-lineage gene transfer, and about its effects on the recipient organism's physiology and fitness. Here, we address these questions in a parallel evolution experiment with two Bacillus subtilis lineages of 7% sequence divergence. We observe rapid evolution of hybrid organisms: gene transfer swaps ~12% of the core genome in just 200 generations, and 60% of core genes are replaced in at least one population. By genomics, transcriptomics, fitness assays, and statistical modeling, we show that transfer generates adaptive evolution and functional alterations in hybrids. Specifically, our experiments reveal a strong, repeatable fitness increase of evolved populations in the stationary growth phase. By genomic analysis of the transfer statistics across replicate populations, we infer that selection on HGT has a broad genetic basis: 40% of the observed transfers are adaptive. At the level of functional gene networks, we find signatures of negative and positive selection, consistent with hybrid incompatibilities and adaptive evolution of network functions. Our results suggest that gene transfer navigates a complex cross-lineage fitness landscape, bridging epistatic barriers along multiple high-fitness paths.

Effects of Polyethylene Microplastics on Freshwater Oligochaeta Allonais inaequalis (Stephenson, 1911) Under Conventional and Stressful Exposures

Abstract: The occurrence of microplastics in the aquatic environment has been reported around the world; however, their effects on freshwater oligochaetes are unknown. In this research, we investigated the toxic effects of polyethylene microplastics (MP), size between 40 and 48 μm, on the aquatic worm Allonais inaequalis. We applied the bioassays considering 24 °C as standard temperature and thermal stress of 19 °C and 29 °C, associated with the presence and absence of sediment in short-term and chronic exposures (96 h and 240 h, respectively). MP did not cause significant mortality in short-term exposures and did not affect the reproduction of worms. In addition, when we analyzed whether thermal stress, as well as substrate availability, would have an additional impact on MP toxicity, there were no significant effects. At 29 °C, the individuals reached the highest reproduction rates, whereas at 19 °C the offspring significantly reduced. Moreover, the lack of sediment substantially reduced survival rates after 96 h under 24 °C (p = 0.018). This paper also records for the first time, the ability of microplastic ingestion by a freshwater naidid. Due to its capacity to respond in a short period, adaptation to laboratory cultivation, and representativeness among freshwater aquatic invertebrates, A. inaequalis is presented as a tropical test organism for toxic effect analysis of microplastics, either in conventional exposures or simulated environmental disturbances.

Metabolic fitness landscapes predict the evolution of antibiotic resistance.

Abstract: Bacteria evolve resistance to antibiotics by a multitude of mechanisms. A central, yet unsolved question is how resistance evolution affects cell growth at different drug levels. Here, we develop a fitness model that predicts growth rates of common resistance mutants from their effects on cell metabolism. The model maps metabolic effects of resistance mutations in drug-free environments and under drug challenge; the resulting fitness trade-off defines a Pareto surface of resistance evolution. We predict evolutionary trajectories of growth rates and resistance levels, which characterize Pareto resistance mutations emerging at different drug dosages. We also predict the prevalent resistance mechanism depending on drug and nutrient levels: low-dosage drug defence is mounted by regulation, evolution of distinct metabolic sectors sets in at successive threshold dosages. Evolutionary resistance mechanisms include membrane permeability changes and drug target mutations. These predictions are confirmed by empirical growth inhibition curves and genomic data of Escherichia coli populations. Our results show that resistance evolution, by coupling major metabolic pathways, is strongly intertwined with systems biology and ecology of microbial populations.

Bose-Einstein condensation in a gas of sodium atoms

Abstract: Bose-Einstein condensation (BEC) has been observed in a dilute gas of sodium atoms. A Bose-Einstein condensate consists of a macroscopic population of the ground state of the system, and is a coherent state of matter. In an ideal gas, this phase transition is purely quantum-statistical. The study of BEC in weakly interacting systems which can be controlled and observed with precision holds the promise of revealing new macroscopic quantum phenomena that can be understood from first principles.

Bose-Einstein condensation

Abstract: When a gas of bosonic particles is cooled below a critical temperature, it condenses into a Bose-Ei…

Environmental Science and Technology

Abstract: The Department of Environmental Science and Technology (ENST) is The Place for Ecological Discovery and Natural Solutions! Our primary mission is to educate students on the fundamentals of environmental science, while instilling a deep fascination and intellectual capacity to work in their chosen area of specialization, whether its Natural Resources Management, Ecological Design, Soil and Watershed Science or Environmental Health. When our students graduate, we want them to be top-notch environmental stewards with a broad framework from which they can advance professionally, personally and socially.

Short-range Quantum Magnetism of Ultracold Fermions in an Optical Lattice

Abstract: Fermionic Quantum Magnetism Optical lattices loaded with cold atoms have been used successfully as quantum simulators of condensed matter systems; however, in the case of fermionic quantum magnetism, achieving low enough temperatures has been a major obstacle. Greif et al. (p. 1307, published online 23 May; see the Perspective by Porto) selectively tuned the exchange interactions in an optical lattice of fermions, forcing a redistribution of entropy such that in the low-entropy subsystem the effective temperature was sufficiently low enough to lead to magnetic correlations. A redistribution of entropy in an optical lattice loaded with atoms leads to magnetic correlations. [Also see Perspective by Porto] Quantum magnetism originates from the exchange coupling between quantum mechanical spins. Here, we report on the observation of nearest-neighbor magnetic correlations emerging in the many-body state of a thermalized Fermi gas in an optical lattice. The key to obtaining short-range magnetic order is a local redistribution of entropy, which allows temperatures below the exchange energy for a subset of lattice bonds. When loading a repulsively interacting gas into either dimerized or anisotropic simple cubic configurations of a tunable-geometry lattice, we observe an excess of singlets as compared with triplets consisting of two opposite spins. For the anisotropic lattice, the transverse spin correlator reveals antiferromagnetic correlations along one spatial axis. Our work facilitates addressing open problems in quantum magnetism through the use of quantum simulation.

Imaging the Mott insulator shells using atomic clock shifts

Abstract: Microwave spectroscopy was used to probe the superfluid–Mott insulator transition of a Bose-Einstein condensate in a three-dimensional optical lattice. By using density-dependent transition frequency shifts, we were able to spectroscopically distinguish sites with different occupation numbers and to directly image sites with occupation numbers from one to five, revealing the shell structure of the Mott insulator phase. We used this spectroscopy to determine the onsite interaction and lifetime for individual shells.