Scalable and Energy-Efficient Millimeter Massive MIMO Architectures: Reflect-Array and Transmit-Array Antennas

Hybrid analog-digital architectures are considered as promising candidates for implementing millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) systems since they enable a considerable reduction of the required number of costly radio frequency (RF) chains by moving some of the signal processing operations into the analog domain. However, the analog feed network, comprising RF dividers, combiners, phase shifters, and line connections, of hybrid MIMO architectures is not scalable due to its prohibitively high power consumption for large numbers of transmit antennas. Motivated by this limitation, in this paper, we study novel massive MIMO architectures, namely reflect-array (RA) and transmit-array (TA) antennas. We show that the precoders for RA and TA antennas have to meet different constraints compared to those for conventional MIMO architectures. Taking these constraints into account and exploiting the sparsity of mmWave channels, we design an efficient precoder for RA and TA antennas based on the orthogonal matching pursuit algorithm. Furthermore, in order to fairly compare the performance of RA and TA antennas with conventional fully-digital and hybrid MIMO architectures, we develop a unified power consumption model. Our simulation results show that unlike conventional MIMO architectures, RA and TA antennas are highly energy efficient and fully scalable in terms of the number of transmit antennas.Comment: submitted to IEEE ICC 201

A device for single leaf labelling with CO2 isotopes to study carbon allocation and partitioning in Arabidopsis thaliana

BACKGROUND: Plant biomass consists primarily of carbohydrates derived from photosynthesis. Monitoring the assimilation of carbon via the Calvin-Benson cycle and its subsequent utilisation is fundamental to understanding plant growth. The use of stable and radioactive carbon isotopes, supplied to plants as CO(2), allows the measurement of fluxes through the intermediates of primary photosynthetic metabolism, long-distance transport of sugars in the vasculature, and the synthesis of structural and storage components. RESULTS: Here we describe the design of a system for supplying isotopically labelled CO(2) to single leaves of Arabidopsis thaliana. We demonstrate that the system works well using short pulses of (14)CO(2) and that it can be used to produce robust qualitative and quantitative data about carbon export from source leaves to the sink tissues, such as the developing leaves and the roots. Time course experiments show the dynamics of carbon partitioning between storage as starch, local production of biomass, and export of carbon to sink tissues. CONCLUSION: This isotope labelling method is relatively simple to establish and inexpensive to perform. Our use of (14)CO(2) helps establish the temporal and spatial allocation of assimilated carbon during plant growth, delivering data complementary to those obtained in recent studies using (13)CO(2) and MS-based metabolomics techniques. However, we emphasise that this labelling device could also be used effectively in combination with (13)CO(2) and MS-based techniques

Novel blood protein based scaffolds for cardiovascular tissue engineering

A major challenge in cardiovascular tissue engineering is the fabrication of scaffolds, which provide appropriate morphological and mechanical properties while avoiding undesirable immune reactions. In this study electrospinning was used to fabricate scaffolds out of blood proteins for cardiovascular tissue engineering. Lyophilised porcine plasma was dissolved in deionised water at a final concentration of 7.5% m/v and blended with 3.7% m/v PEO. Electrospinning resulted in homogeneous fibre morphologies with a mean fibre diameter of 151 nm, which could be adapted to create macroscopic shapes (mats, tubes). Cross-linking with glutaraldehyde vapour improved the long-term stability of protein based scaffolds in comparison to untreated scaffolds, resulting in a mass loss of 41% and 96% after 28 days of incubation in aqueous solution, respectively

Are landscape structures insurmountable barriers for foraging bees? A mark-recapture study with two solitary pollen specialist species

To investigate whether landscape structures act as insurmountable barriers for foraging bees, we conducted mark-recapture studies with two pollen-specialist solitary species. Foraging options of the bees were confined to host plant stands across different landscape structures. Differences in altitude of more than 130 m were overcome and forests covering a distance of up to 480 m were crossed by Chelostoma florisomne. A broad river and a motorway with intense traffic did not represent insurmountable barriers for Hoplitis adunca. For C. florisomne, total foraging distances of up to 650 m were measured, but foraging females were recorded predominantly on host plant patches available in relatively close vicinity to their nesting site. While landscape structures might impede foraging in endangered bees, the investigated landscape structures clearly did not act as insurmountable physical barriers for the two common solitary bee species tested in our stud

THE EMERGENCE OF LEISURE TRAVEL AS PRIMARY PREVENTIVE TOOLS IN EMPLOYEE HEALTH BEHAVIOR

In our current modern world, it can be said that it is very difficult to live a balanced and healthy life, and to always perform well in the world of work, so it is very important to pay attention to our leisure time and our primary prevention activities, which can help preserve our health and improve our fitness. The purpose of the research is to examine the appearance of leisure tourist trips among employees, and how tourist trips appear among the primary prevention tools. Our research found answers to the main questions of what activities employees try to regain their ability to work, and whether trips are popular as primary prevention activities. The recreational activities of the employees are primarily filled by various obligations, but at the same time, the use of primary prevention activities is pushed into the background during everyday life. During the research, we established that medical and wellness holidays are very popular among the respondents, as 22.5% of the sample (133 people) take part in medical tourism holidays and 50.3% of the respondents (297 people) take part in health care on a focused wellness holiday. The quiet, calm environment and the closeness to nature, which helps the employees to regenerate, appeared prominently in the motivation for the choice of destination. Among primary prevention tools, leisure activities spent with family, relationships, and friends, healthy eating, and walking and nature walks are the ones that appear dominantly in the everyday life of employees. In order to reduce the problem of burnout, pressure to perform, and stress among employees and to enable them to perform well in their tasks, it is very important to assess their needs and provide them with programs that contribute to improving their health and regaining their ability to work, such as appropriate recreation programs and various trips

Die Latenzphase meistern : was brauchen Frauen?

Text auch in französisch (Seite 20-23)Gebärende Frauen stehen vor der Herausforderung, die Latenzphase oft ohne professionelle Unterstützung zu meistern. Es liegt in ihrer Verantwortung, den Geburtsbeginn zu diagnostizieren und den richtigen Zeitpunkt zu erkennen, um professionelle Unterstützung zu suchen. Die institutionellen Leitlinien der Spitäler zielen darauf ab, Gebärende erst mit fortschreitender Geburt aufzunehmen. Studien zeigen, dass ein früher Spitaleintritt mit negativen geburtshilflichen Outcomes sowie höheren Interventionsraten, beispielsweise Wehenförderung und Periduralanästhesie, verbunden ist. Deshalb wird Frauen in der Latenzphase oft geraten, zu Hause zu bleiben, was überfordernd und unbefriedigend sein kann. Ziel der aktuellen Studie war es, das Selbst- und professionelle Management und den Betreuungsbedarf von Erstgebärenden in der Latenzphase zu untersuchen

Intelligent Surface-Aided Transmitter Architectures for Millimeter Wave Ultra Massive MIMO Systems

In this paper, we study two novel massive multiple-input multiple-output (MIMO) transmitter architectures for millimeter wave (mmWave) communications which comprise few active antennas, each equipped with a dedicated radio frequency (RF) chain, that illuminate a nearby large intelligent reflecting/transmitting surface (IRS/ITS). The IRS (ITS) consists of a large number of low-cost and energy-efficient passive antenna elements which are able to reflect (transmit) a phase-shifted version of the incident electromagnetic field. Similar to lens array (LA) antennas, IRS/ITS-aided antenna architectures are energy efficient due to the almost lossless over-the-air connection between the active antennas and the intelligent surface. However, unlike for LA antennas, for which the number of active antennas has to linearly grow with the number of passive elements (i.e., the lens aperture) due to the non-reconfigurablility (i.e., non-intelligence) of the lens, for IRS/ITS-aided antennas, the reconfigurablility of the IRS/ITS facilitates scaling up the number of radiating passive elements without increasing the number of costly and bulky active antennas. We show that the constraints that the precoders for IRS/ITS-aided antennas have to meet differ from those of conventional MIMO architectures. Taking these constraints into account and exploiting the sparsity of mmWave channels, we design two efficient precoders; one based on maximizing the mutual information and one based on approximating the optimal unconstrained fully digital (FD) precoder via the orthogonal matching pursuit algorithm. Furthermore, we develop a power consumption model for IRS/ITS-aided antennas that takes into account the impacts of the IRS/ITS imperfections, namely the spillover loss, taper loss, aperture loss, and phase shifter loss.Comment: Journal version of arXiv:1811.0294

Early labour : women’s expectations and experiences

Background: Early labour care is a major challenge for all involved. A women-centred approach that considers women’s needs requires more knowledge about their individual experiences. Therefore, this study aimed to generate in-depth knowledge of primiparous women’s preparation for early labor as well as their expectations and experiences of physical and emotional symptoms of onset of labor. Method and Material: We conducted four focus group discussions with n=18 women who had given birth to their first child in the previous six months. Two researchers coded and summarised the women's statements into themes. Qualitative content analysis was applied using Atlas.ti 9. Findings: Four themes emerged from women’s narratives: ‘Preparing for the unpredictable’, ‘Expectations and reality’, ‘Perception and wellbeing’ and ‘Experiencing the beginning of birth’. Many women could not distinguish the preparation for early labour from that for the whole birth. Relaxation techniques were very much appreciated as antenatal preparation. Not meeting expectations was a big challenge for many women. For instance, some participants were surprised about the intensity of contractions and others felt pleased how well they could cope with them. Physical and emotional symptoms of onset of labour differed greatly from woman to woman. Some parturients were positively excited, yet others were anxious about the unknown. Additionally, some women had great difficulties with sleep deprivation. Early labor at home was mostly experienced positively, whereas early labor at the hospital was sometimes difficult, because women felt neglected and being in the second rank. Conclusion: The individual character of experiencing onset of labour and early labour was striking which highlighted the great need of women-centred early labour care. Further research is needed to investigate how the findings of this study could be used to improve advising and caring for women during early labour