Investigations of a compartmental model for leucine kinetics using nonlinear mixed effects models with ordinary and stochastic differential equations

Nonlinear mixed effects models represent a powerful tool to simultaneously analyze data from several individuals. In this study a compartmental model of leucine kinetics is examined and extended with a stochastic differential equation to model non-steady state concentrations of free leucine in the plasma. Data obtained from tracer/tracee experiments for a group of healthy control individuals and a group of individuals suffering from diabetes mellitus type 2 are analyzed. We find that the interindividual variation of the model parameters is much smaller for the nonlinear mixed effects models, compared to traditional estimates obtained from each individual separately. Using the mixed effects approach, the population parameters are estimated well also when only half of the data are used for each individual. For a typical individual the amount of free leucine is predicted to vary with a standard deviation of 8.9% around a mean value during the experiment. Moreover, leucine degradation and protein uptake of leucine is smaller, proteolysis larger, and the amount of free leucine in the body is much larger for the diabetic individuals than the control individuals. In conclusion nonlinear mixed effects models offers improved estimates for model parameters in complex models based on tracer/tracee data and may be a suitable tool to reduce data sampling in clinical studies

Spectral noise in quantum frequency down-conversion from the visible to the telecommunication C-band

We report a detailed study of the noise properties of a visible-to-telecom photon frequency converter based on difference frequency generation (DFG). The device converts 580 nm photons to 1541 nm using a strong pump laser at 930 nm, in a periodically poled lithium niobate ridge waveguide. The converter reaches a maximum device efficiency of 46 % (internal efficiency of 67 %) at a pump power of 250 mW. The noise produced by the pump laser is investigated in detail by recording the noise spectra both in the telecom and visible regimes, and measuring the power dependence of the noise rates. The noise spectrum in the telecom is very broadband, as expected from previous work on similar DFG converters. However, we also observe several narrow dips in the telecom spectrum, with corresponding peaks appearing in the 580 nm noise spectrum. These features are explained by sum frequency generation of the telecom noise at wavelengths given by the phase matching condition of different spatial modes in the waveguide. The proposed noise model is in good agreement with all the measured data, including the power-dependence of the noise rates, both in the visible and telecom regime. These results are applicable to the class of DFG converters where the pump laser wavelength is in between the input and target wavelength.Comment: 10 page

Confronting SUSY models with LHC data via electroweakino production

We investigate multi-lepton signals produced by ElectroWeakino (EWino) decays in the MSSM and the TMSSM scenarios with sfermions, gluinos and non Standard Model Higgses at the TeV scale, being the Bino electroweak-scale dark matter. We recast the present LHC constraints on EWinos for these models and we find that wide MSSM and TMSSM parameter regions prove to be allowed. We forecast the number of events expected in the signal regions of the experimental multi-lepton analyses in the next LHC runs. The correlations among these numbers will help to determine whether future deviations in multi-lepton data are ascribable to the EWinos, as well as the supersymmetric model they originate from.Comment: 33 pages, 10 figures, 3 table

Multi-physic system simplification method applied to a helicopter flight axis active control

A helicopter flight axis control, which is a complex multi-physic system, is modelled using an energetic based graphical tool: the Energetic Macroscopic Representation. Elements of the system are mainly composed of passive technologies and their number tends to increase year after year to improve the pilots comfort by adding new functions. A new methodology is proposed to transform the system into a new active one by replacing some hydro-mechanical elements by a new controllable active mechanical source. The challenge is to simplify the flight control architecture while preserving the global behaviour of the system

Efficient Stochastic Programming in Julia

We present StochasticPrograms.jl, a user-friendly and powerful open-source framework for stochastic programming written in the Julia language. The framework includes both modeling tools and structure-exploiting optimization algorithms. Stochastic programming models can be efficiently formulated using expressive syntax and models can be instantiated, inspected, and analyzed interactively. The framework scales seamlessly to distributed environments. Small instances of a model can be run locally to ensure correctness, while larger instances are automatically distributed in a memory-efficient way onto supercomputers or clouds and solved using parallel optimization algorithms. These structure-exploiting solvers are based on variations of the classical L-shaped and progressive-hedging algorithms. We provide a concise mathematical background for the various tools and constructs available in the framework, along with code listings exemplifying their usage. Both software innovations related to the implementation of the framework and algorithmic innovations related to the structured solvers are highlighted. We conclude by demonstrating strong scaling properties of the distributed algorithms on numerical benchmarks in a multi-node setup

The stigma of stress and the absence of agency

Seit mehr als 15 Jahren ist Stress ein zentrales Thema und Motiv innerhalb der dänischen Diskurse zum Verhältnis von Arbeit und Leben. Täglich melden sich bis zu 35.000 Beschäftigte aufgrund von stressbedingten Symptomen am Arbeitsplatz krank. Darüber hinaus wird geschätzt, dass stressbedingte Ausfälle und Behandlungen die dänische Gesellschaft ca. 1,9 Mrd. Euro jährlich kosten. Stress ist insofern eine ernste Bedrohung sowohl für die körperliche als auch für die geistige Gesundheit der Einzelnen auf der einen, sowie für das allgemeine Wohl der Bevölkerung auf der anderen Seite. Auffällig an den untersuchten Stress-Diskursen ist die weitgehende Abwesenheit von Handlungsmacht und/oder konkreten Handlungsempfehlungen zur Bewältigung von arbeitsbedingtem Stress innerhalb der Phänomenkonstitution dieser Diskurse. Der folgende Artikel untersucht die Formierung der dominanten dänischen Stress-Diskurse, die sich durch eine Stigmatisierung von stressbedingter Arbeitsunfähigkeit bei gleichzeitiger Ausblendung von Handlungsmacht bzw. -optionen auszeichnen anhand einer Analyse dänischer Management- und Führungszeitschriften.For more than 15 years, stress has set the agenda in the Danish work-life discourses. Every day 35,000 employees are reportedly absent from work due to stress-related illnesses, and stress is estimated to cost the Danish society approx. 1,9 billion Euro per year. Stress is a serious threat to both physical and mental health as well as to the general well-being of the population. Compared to other discourses, the discourse on stress is characterized by a notable lack of agency or policies for how to act or, in this case, ways to deal with stress. This article describes how a substantial discourse on stress in Danish journals on leadership and management and in newspapers over a decade has contributed to creating an intricate stress stigma and an absence of agency

How to understand and handle divergent views on the need for leadership interventions: a social constructionist approach

This paper addresses the challenge of how to understand and handle divergent views on the need for leadership interventions between managers and subordinates. Recent popular discourses of leadership, such as the authentic leadership perspective, privileges the potential leader himself or herself as the origin of leadership. This perspective thereby neglects the view of the followers and the essentially socially constructed relationship between leaders and followers. Based upon a critique against essentialist views of leadership such as authentic leadership we suggest a model on how to analyse divergent views between leaders and followers and its implications regarding managerial discretion regarding leadership initiatives

Realizing strong light-matter interactions between single nanoparticle plasmons and molecular excitons at ambient conditions

Realizing strong light-matter interactions between individual 2-level systems and resonating cavities in atomic and solid state systems opens up possibilities to study optical nonlinearities on a single photon level, which can be useful for future quantum information processing networks. However, these efforts have been hampered by the unfavorable experimental conditions, such as cryogenic temperatures and ultrahigh vacuum, required to study such systems and phenomena. Although several attempts to realize strong light-matter interactions at room-temperature using so-called plasmon resonances have been made, successful realizations on the single nanoparticle level are still lacking. Here, we demonstrate strong coupling between plasmons confined within a single silver nanoprism and excitons in molecular J-aggregates at ambient conditions. Our findings show that the deep subwavelength mode volumes, $V$, together with high quality factors, $Q$, associated with plasmons in the nanoprisms result in strong coupling figure-of-merit -- $Q/\sqrt{V}$ as high as $\sim6\times10^{3}$~$\mu$m$^{-3/2}$ -- a value comparable to state-of-art photonic crystal and microring resonator cavities, thereby suggesting that plasmonic nanocavities and specifically silver nanoprisms can be used for room-temperature quantum optics