Confinement induced interlayer molecules: a route to strong interatomic interactions

We study theoretically the interaction between two species of ultracold atoms confined into two layers of a finite separation, and demonstrate the existence of new types of confinement-induced interlayer bound and quasi-bound molecules: these novel exciton-like interlayer molecules appear for both positive and negative scattering lengths, and exist even for layer separations many times larger than the interspecies scattering length. The lifetime of the quasi-bound molecules grows exponentially with increasing layer separation, and they can therefore be observed in simple shaking experiments, as we demonstrate through detailed many-body calculations. These quasi-bound molecules can also give rise to novel interspecies Feshbach resonances, enabling one to control geometrically the interaction between the two species by changing the layer separation. Rather counter-intuitively, the species can be made strongly interacting, by increasing their spatial separation. The separation induced interlayer resonances provide a powerful tool for the experimental control of interspecies interactions and enables one to realize novel quantum phases of multicomponent quantum gases.Comment: 13 pages, 9 figure

Shortest path discovery of complex networks

In this paper we present an analytic study of sampled networks in the case of some important shortest-path sampling models. We present analytic formulas for the probability of edge discovery in the case of an evolving and a static network model. We also show that the number of discovered edges in a finite network scales much slower than predicted by earlier mean field models. Finally, we calculate the degree distribution of sampled networks, and we demonstrate that they are analogous to a destructed network obtained by randomly removing edges from the original network.Comment: 10 pages, 4 figure

Answer to a question of Kolmogorov

More than 80 years ago Kolmogorov asked the following question. Let E ⊆ R 2 E\subseteq \mathbb {R}^{2} be a measurable set with λ 2 ( E ) &gt; ∞ \lambda ^{2}(E)&gt;\infty , where λ 2 \lambda ^2 denotes the two-dimensional Lebesgue measure. Does there exist for every ε &gt; 0 \varepsilon &gt;0 a contraction f : E → R 2 f\colon E\to \mathbb {R}^{2} such that λ 2 ( f ( E ) ) ≥ λ 2 ( E ) − ε \lambda ^{2}(f(E))\geq \lambda ^{2}(E)-\varepsilon and f ( E ) f(E) is a polygon? We answer this question in the negative by constructing a bounded, simply connected open counterexample. Our construction can easily be modified to yield an analogous result in higher dimensions.</p

The Effect of Root Exudate 7,4\u27-Dihydroxyflavone and Naringenin on Soil Bacterial Community Structure

Our goal was to investigate how root exudate flavonoids influence the soil bacterial community structure and to identify members of the community that change their relative abundance in response to flavonoid exudation. Using a model system that approximates flavonoid exudation of Medicago sativa roots, we treated a soil with 7,4′-dihydroxyflavone and naringenin in two separate experiments using three different rates: medium (equivalent to the exudation rate of 7,4′-dihydroxyflavone from M. sativa seedlings), high (10× the medium rate), and low (0.1× the medium rate). Controls received no flavonoid. Soil samples were subjected to ATP assays and 16S rRNA gene amplicon sequencing. The flavonoid treatments caused no significant change in the soil ATP content. With the high 7,4′-dihydroxyflavone treatment rate, operational taxonomic units (OTUs) classified as Acidobacteria subdivision 4 increased in relative abundance compared with the control samples, whereas OTUs classified as Gaiellales, Nocardioidaceae, and Thermomonosporaceae were more prevalent in the control. The naringenin treatments did not cause significant changes in the soil bacterial community structure. Our results suggest that the root exudate flavonoid 7,4′-dihydroxyflavone can interact with a diverse range of soil bacteria and may have other functions in the rhizosphere in addition to nod gene induction in legume—rhizobia symbiosis

Exploring the Kondo model in and out of equilibrium with alkaline-earth atoms

We propose a scheme to realize the Kondo model with tunable anisotropy using alkaline-earth atoms in an optical lattice. The new feature of our setup is Floquet engineering of interactions using time-dependent Zeeman shifts, that can be realized either using state-dependent optical Stark shifts or magnetic fields. The properties of the resulting Kondo model strongly depend on the anisotropy of the ferromagnetic interactions. In particular, easy-plane couplings give rise to Kondo singlet formation even though microscopic interactions are all ferromagnetic. We discuss both equilibrium and dynamical properties of the system that can be measured with ultracold atoms, including the impurity spin susceptibility, the impurity spin relaxation rate, as well as the equilibrium and dynamical spin correlations between the impurity and the ferromagnetic bath atoms. We analyze the non-equilibrium time evolution of the system using a variational non-Gaussian approach, which allows us to explore coherent dynamics over both short and long timescales, as set by the bandwidth and the Kondo singlet formation, respectively. In the quench-type experiments, when the Kondo interaction is suddenly switched on, we find that real-time dynamics shows crossovers reminiscent of poor man's renormalization group flow used to describe equilibrium systems. For bare easy-plane ferromagnetic couplings, this allows us to follow the formation of the Kondo screening cloud as the dynamics crosses over from ferromagnetic to antiferromagnetic behavior. On the other side of the phase diagram, our scheme makes it possible to measure quantum corrections to the well-known Korringa law describing the temperature dependence of the impurity spin relaxation rate. Theoretical results discussed in our paper can be measured using currently available experimental techniques.Comment: 22 pages, 12 figure

Robust peak detection for photoplethysmography signal analysis

Efficient and accurate evaluation of long-term photoplethysmography (PPG) recordings is essential for both clinical assessments and consumer products. In 2021, the top opensource peak detectors were benchmarked on the Multi-Ethnic Study of Atherosclerosis (MESA) database consisting of polysomnography (PSG) recordings and continuous sleep PPG data, where the Automatic Beat Detector (Aboy) had the best accuracy. This work presents Aboy++, an improved version of the original Aboy beat detector. The algorithm was evaluated on 100 adult PPG recordings from the MESA database, which contains more than 4.25 million reference beats. Aboy++ achieved an F1-score of 85.5%, compared to 80.99% for the original Aboy peak detector. On average, Aboy++ processed a 1 hour-long recording in less than 2 seconds. This is compared to 115 seconds (i.e., over 57-times longer) for the open-source implementation of the original Aboy peak detector. This study demonstrated the importance of developing robust algorithms like Aboy++ to improve PPG data analysis and clinical outcomes. Overall, Aboy++ is a reliable tool for evaluating long-term wearable PPG measurements in clinical and consumer contexts.Comment: 4 pages, 1 figure, 50th Computing in Cardiology conference in Atlanta, Georgia, USA on 1st - 4th October 202