Pattern Formation in One-Dimensional Polaron Systems and Temporal Orthogonality Catastrophe

Recent studies have demonstrated that higher than two-body bath-impurity correlations are not important for quantitatively describing the ground state of the Bose polaron. Motivated by the above, we employ the so-called Gross Ansatz (GA) approach to unravel the stationary and dynamical properties of the homogeneous one-dimensional Bose-polaron for different impurity momenta and bath-impurity couplings. We explicate that the character of the equilibrium state crossovers from the quasi-particle Bose polaron regime to the collective-excitation stationary dark-bright soliton for varying impurity momentum and interactions. Following an interspecies interaction quench the temporal orthogonality catastrophe is identified, provided that bath-impurity interactions are sufficiently stronger than the intraspecies bath ones, thus generalizing the results of the confined case. This catastrophe originates from the formation of dispersive shock wave structures associated with the zero-range character of the bath-impurity potential. For initially moving impurities, a momentum transfer process from the impurity to the dispersive shock waves via the exerted drag force is demonstrated, resulting in a final polaronic state with reduced velocity. Our results clearly demonstrate the crucial role of non-linear excitations for determining the behavior of the one-dimensional Bose polaron.

One-BEC-species coherent oscillations with frequency controlled by a second species atom number

Controlling the tunneling of atoms of one species using a different atom species is a fundamental step in the development of a new class of atom quantum devices, where detection, motion control, and other functions over the atoms, can be achieved by exploiting the interaction between two different atomic species. Here, we theoretically study coherent oscillations of a non-self-interacting Bose-Einstein condensate (BEC) species in a triple-well potential controlled by a self-interacting species self-trapped in the central well of the potential. In this system, a blockade, due to the interspecies interaction, prevents atoms of the non-self-interacting species from populating the central well. Thus, for an initial population imbalance between the left- and right-hand wells of the non-self-interacting species, coherent BEC oscillations are induced between these two wells, resembling those of Rabi-like BEC oscillations in a double-well potential. The oscillation period is found to scale linearly with the number of self-trapped atoms as well as with the interspecies interaction strength. This behavior is corroborated by the quantum many-particle and the mean-field models of the system. We show that BEC oscillations can be described by using an effective bosonic Josephson junction with a tunneling amplitude that depends on the number of the self-trapped atoms in the central well. We also consider the effect of the self-trapped atom losses on the coherent oscillations. We show, by using quantum trajectories, that this type of losses leads to a dynamical change in the oscillation period of the non-self-interacting species, which in turn allows the number of self-trapped atoms lost from the system to be estimated.

Persistence of functional microbiota composition across generations

Holobionts are defined as a host and its microbiota, however, only a fraction of the bacteria are inherited vertically and thus coevolve with the host. The “it’s the song, not the singer” theory proposes that functional traits, instead of taxonomical microbiota composition, could be preserved across generations if interspecies interaction patterns perpetuate themselves. We tested conservation of functional composition across generations using zooplankton, mosquito, and plant datasets. Then, we tested if there is a change of functional microbiota composition over time within a generation in human datasets. Finally, we simulated microbiota communities to investigate if (pairwise) interactions can lead to multiple stable community compositions. Our results suggest that the vertically transmitted microbiota starts a predictable change of functions performed by the microbiota over time, whose robustness depends on the arrival of diverse migrants. This succession culminates in a stable functional composition state. The results suggest that the host-microbiota interaction and higher order interactions in general have an important contribution to the robustness of the final community. If the proposed mechanism proves to be valid for a diverse array of host species, this would support the concept of holobionts being used as units of selection, including animal breeding, suggesting this has a wider applicability.

Ground-State Properties and Phase Separation of Binary Mixtures in Mesoscopic Ring Lattices

We investigated the spatial phase separation of the two components forming a bosonic mixture distributed in a four-well lattice with a ring geometry. We studied the ground state of this system, described by means of a binary Bose–Hubbard Hamiltonian, by implementing a well-known coherent-state picture which allowed us to find the semi-classical equations determining the distribution of boson components in the ring lattice. Their fully analytic solutions, in the limit of large boson numbers, provide the boson populations at each well as a function of the interspecies interaction and of other significant model parameters, while allowing to reconstruct the non-trivial architecture of the ground-state four-well phase diagram. The comparison with the L-well (L=2,3) phase diagrams highlights how increasing the number of wells considerably modifies the phase diagram structure and the transition mechanism from the full-mixing to the full-demixing phase controlled by the interspecies interaction. Despite the fact that the phase diagrams for L=2,3,4 share various general properties, we show that, unlike attractive binary mixtures, repulsive mixtures do not feature a transition mechanism which can be extended to an arbitrary lattice of size L.

EFFECT OF Staphylococcus epidermidis ON Pseudomonas aeruginosa BIOFILM IN MIXED-SPECIES CULTURE

Staphylococcus epidermidis and Pseudomonas aeruginosa, are clinically relevant pathogens that often produce biofilms. To investigate the co-survivability of S. epidermidis and P. aeruginosa in mixed cultures biofilm and planktonic form, it is important to understand more about the interspecies interaction of both species. The interspecies interaction was analyzed using streak and drop agar plate assay, cell viability assay (CFU), spectrophotometry-based method, and microscopic analysis. The findings suggest that both cells and supernatant of P. aeruginosa inhibit the planktonic growth of S. epidermidis. The cell viability result shows that PAO1 biofilm cells were decreased by 88%, and SE biofilm cells were increased by 75% concerning their control. Opposite to the P. aeruginosa, the S. epidermidis biofilm and EPS matrix were found to increase in mixed culture biofilm, which was further confirmed by microscopic analysis. In contrast, differential agar media result shows that the reduction in the biofilm (CFU/ml) of P. aeruginosa is independent of S. epidermidis cells concentration. Finally, the effect of the supernatant on biofilm was investigated, and it found that S. epidermidis biofilm was enhanced while P. aeruginosa biofilm was reduced in the presence of partner bacterial supernatant, which indicated that S. epidermidis in biofilm mode could hinder the biofilm formation of P. aeruginosa. The outcomes show that the culture supernatant of S. epidermidis can be used to prevent P. aeruginosa associated biofilm infections.

Simulation of three variants of population dynamics with large reproductive potential in a new environment

Предложены модели на основе уравнений с запаздывающей регуляцией и отложенным включением противодействия для динамики инвазивных популяций с высоким репродуктивным потенциалом. В новой среде интродуценты с большим r -параметром способны демонстрировать нестационарные и экстремальные режимы изменения численности из-за некомпенсируемой репродуктивной активности. Истощение необходимых им ресурсов делает невозможными орбитально устойчивые циклы. Уравнения в вычислительных сценариях описывают: 1) стабилизацию малочисленной группы после однократной вспышки и коллапса; 2) гибель вселенца при колебательной динамике с запаздывающим внешним давлением; 3) успешное прохождение популяцией с логистическим типом роста предкритического минимума при адаптации к резко усилившемуся противоборству - распространенный сценарий кризиса на подъеме, подтвержденный экспериментами. Третье уравнение отражает актуальное межвидовое взаимодействие с пороговой регуляцией. Развитие моделируемой ситуации заканчивается стабильным состоянием после глубокого кризиса в фазе быстрого роста численности. Сценарий основан на данных экспериментов с интродукцией вируса-бактериофага в колонию бактерий с механизмом защиты CRISPR-Cas. The research addresses mathematical description of three nontrivial avenues for development of population processes. Such events arise after invasions of aggressive species. Invasive processes do not lead to an equilibrium (stable balance) between ecosystems and the environment or regular cyclical changes. The method we have chosen allows simulation of several variants for the reaction of the environment to the appearance of a competitor with a large reproductive potential. We discarded the idea of interpreting the balance capacity of the ecological niche, but used threshold levels for the reaction of the environment instead. We have proposed models based on equations with delayed regulation and delayed activation of counteraction for the dynamics of invasive populations in an environment without mechanisms controlling their reproduction. Some species, when introduced into a new habitat, are able to demonstrate nonstationary and extreme regimes of growths due to uncompensated reproductive activity. The species with a large r -parameter deplete significant resources they need to live, which make stable development impossible, including orbitally stable cycles. We have developed new equations that describe the following scenarios: 1) boom-bust dynamics stabilization at the level of a small group after a single outbreak is the most common scenario for insect pests; 2) the destruction and disappearance of the invader during the oscillatory dynamics and with the regulation with delayed external pressure; 3) scenario for a threshold crisis - successful passage of a population with a logistic increase in the subcritical minimum while adapting to a suddenly intensified confrontation. It is a frequently observed variant that confirmed by experiments with bacterial colonies. The third variant of our modification of the equation describes the most interesting scenario of interspecies interaction with threshold regulation. Development of simulated situation here ends up in stable state after the deep crisis during phase of rapid growth of the population size. We substantiated the model scenario based on experimental data for introduction of the bacteriophage virus into bacterial colony with the CRISPR-Cas mechanism. Our models can be used to study variability of the immune response.

Candida albicans SET3 Plays a Role in Early Biofilm Formation, Interaction With Pseudomonas aeruginosa and Virulence in Caenorhabditis elegans

The yeast Candida albicans exhibits multiple morphologies dependent on environmental cues. Candida albicans biofilms are frequently polymicrobial, enabling interspecies interaction through proximity and contact. The interaction between C. albicans and the bacterium, Pseudomonas aeruginosa, is antagonistic in vitro, with P. aeruginosa repressing the yeast-to-hyphal switch in C. albicans. Previous transcriptional analysis of C. albicans in polymicrobial biofilms with P. aeruginosa revealed upregulation of genes involved in regulation of morphology and biofilm formation, including SET3, a component of the Set3/Hos2 histone deacetylase complex (Set3C). This prompted the question regarding the involvement of SET3 in the interaction between C. albicans and P. aeruginosa, both in vitro and in vivo. We found that SET3 may influence early biofilm formation by C. albicans and the interaction between C. albicans and P. aeruginosa. In addition, although deletion of SET3 did not alter the morphology of C. albicans in the presence of P. aeruginosa, it did cause a reduction in virulence in a Caenorhabditis elegans infection model, even in the presence of P. aeruginosa.