Microparticle Transport and Sedimentation in a Rhythmically Expanding Alveolar Chip.

Understanding the mechanism of particle transport and sedimentation in pulmonary alveolus is important for deciphering the causes of respiratory diseases and helping the development of drug delivery. In this study, taking advantage of the microfluidic technique, an experimental platform was developed to study particle behavior in a rhythmically expanding alveolar chip for a sufficient number of cycles. The alveolar flow patterns at different generations were measured for two cases with the gravity direction parallel or vertical to the alveolar duct. Affected by both the vortex flow inside the alveoli and the shear flow in the duct simultaneously, it was observed that particles inside the alveoli either escaped from the inlet of the alveolar duct or stayed in the alveoli, revealing the irreversibility of particle transport in the alveoli. At the earlier acinar generations, particles were inclined to deposit on the distal alveolar wall. The settling rates of particles of different sizes in the alveoli were also compared. This study provides valuable data for understanding particle transport and sedimentation in the alveoli.

Cluster-based network modeling-From snapshots to complex dynamical systems.

We propose a universal method for data-driven modeling of complex nonlinear dynamics from time-resolved snapshot data without prior knowledge. Complex nonlinear dynamics govern many fields of science and engineering. Data-driven dynamic modeling often assumes a low-dimensional subspace or manifold for the state. We liberate ourselves from this assumption by proposing cluster-based network modeling (CNM) bridging machine learning, network science, and statistical physics. CNM describes short- and long-term behavior and is fully automatable, as it does not rely on application-specific knowledge. CNM is demonstrated for the Lorenz attractor, ECG heartbeat signals, Kolmogorov flow, and a high-dimensional actuated turbulent boundary layer. Even the notoriously difficult modeling benchmark of rare events in the Kolmogorov flow is solved. This automatable universal data-driven representation of complex nonlinear dynamics complements and expands network connectivity science and promises new fast-track avenues to understand, estimate, predict, and control complex systems in all scientific fields.

Typhus Group Rickettsiosis, Germany, 2010-20171.

Typhus group rickettsiosis is caused by the vectorborne bacteria Rickettsia typhi and R. prowazekii. R. typhi, which causes murine typhus, the less severe endemic form of typhus, is transmitted by fleas; R. prowazekii, which causes the severe epidemic form of typhus, is transmitted by body lice. To examine the immunology of human infection with typhus group rickettsiae, we retrospectively reviewed clinical signs and symptoms, laboratory changes, and travel destinations of 28 patients who had typhus group rickettsiosis diagnosed by the German Reference Center for Tropical Pathogens, Hamburg, Germany, during 2010-2017. Immunofluorescence assays of follow-up serum samples indicated simultaneous seroconversion of IgM, IgA, and IgG or concurrence in the first serum sample. Cytokine levels peaked during the second week of infection, coinciding with organ dysfunction and seroconversion. For 3 patients, R. typhi was detected by species-specific nested quantitative PCR. For all 28 patients, R. typhi was the most likely causative pathogen.

New Lineage of Lassa Virus, Togo, 2016.

We describe a strain of Lassa virus representing a putative new lineage that was isolated from a cluster of human infections with an epidemiologic link to Togo. This finding extends the known range of Lassa virus to Togo.

Prediction of dynamical systems by symbolic regression.

We study the modeling and prediction of dynamical systems based on conventional models derived from measurements. Such algorithms are highly desirable in situations where the underlying dynamics are hard to model from physical principles or simplified models need to be found. We focus on symbolic regression methods as a part of machine learning. These algorithms are capable of learning an analytically tractable model from data, a highly valuable property. Symbolic regression methods can be considered as generalized regression methods. We investigate two particular algorithms, the so-called fast function extraction which is a generalized linear regression algorithm, and genetic programming which is a very general method. Both are able to combine functions in a certain way such that a good model for the prediction of the temporal evolution of a dynamical system can be identified. We illustrate the algorithms by finding a prediction for the evolution of a harmonic oscillator based on measurements, by detecting an arriving front in an excitable system, and as a real-world application, the prediction of solar power production based on energy production observations at a given site together with the weather forecast.

Sharp increase of imported Plasmodium vivax malaria seen in migrants from Eritrea in Hamburg, Germany.

BACKGROUND: Since 2014, a considerable increase in Plasmodium vivax malaria has been observed in Germany. The majority of cases was seen in Eritrean refugees. METHODS: All patients with P. vivax malaria admitted to the University Medical Centre Hamburg-Eppendorf Germany from 2011 until August 2015 were retrospectively identified by the hospital coding system and data was matched with records from the laboratory diagnostics unit of the Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany. RESULTS: Between May 2014 and August 2015, 37 cases were reported in newly-arrived Eritrean refugees at the University Medical Centre Hamburg-Eppendorf, Germany. Relapses occurred due to difficulties in procurement of primaquine. CONCLUSION: Countries hosting Eritrean refugees need to be aware of vivax malaria occurring in this group and the risk of autochthonous cases due to local transmission by indigenous, vector competent Anopheles species.

The Prevalence of Sickle Cell Disease and Its Implication for Newborn Screening in Germany (Hamburg Metropolitan Area).

Sickle cell disease is among hereditary diseases with evidence that early diagnoses and treatment improves the clinical outcome. So far sickle cell disease has not been included in the German newborn screening program despite immigration from countries with populations at risk. To determine the birth prevalence we tested 17,018 newborns. High pressure liquid chromatography and subsequent molecular-genetic testing were used for the detection and confirmation of hemoglobin variants. The frequency of sickle cell disease-consistent genotypes was one in 2,385 newborns. Duffy-blood group typing showed evidence that affected children were likely of Sub-Saharan ancestry. An inclusion of sickle cell disease into the German newborn screening seems reasonable.

Reduced-order models for closed-loop wake control.

We review a strategy for low- and least-order Galerkin models suitable for the design of closed-loop stabilization of wakes. These low-order models are based on a fixed set of dominant coherent structures and tend to be incurably fragile owing to two challenges. Firstly, they miss the important stabilizing effects of interactions with the base flow and stochastic fluctuations. Secondly, their range of validity is restricted by ignoring mode deformations during natural and actuated transients. We address the first challenge by including shift mode(s) and nonlinear turbulence models. The resulting robust least-order model lives on an inertial manifold, which links slow variations in the base flow and coherent and stochastic fluctuation amplitudes. The second challenge, the deformation of coherent structures, is addressed by parameter-dependent modes, allowing smooth transitions between operating conditions. Now, the Galerkin model lives on a refined manifold incorporating mode deformations. Control design is a simple corollary of the distilled model structure. We illustrate the modelling path for actuated wake flows.