Quantum networks connect quantum processors or quantum sensors with each other. This allows tap-proof communication and high-performance distributed sensor networks. Between network nodes, quantum information is exchanged by photons that travel through optical waveguides. Over long distances, however, the likelihood of photons being lost increases dramatically. As quantum information cannot simply be copied and amplified, 25 years ago Hans Briegel, Wolfgang Dür, Ignacio Cirac and Peter Zoller, then all at the University of Innsbruck, provided the blueprints for a quantum repeater. These feature light-matter entanglement sources and memories to create entanglement in independent network links that are connected between them by a so-called entanglement swap to finally distribute entanglement over long distances.

Even transmission over 800 kilometers possible

Quantum physicists led by Ben Lanyon from the Department of Experimental Physics at the University of Innsbruck have now succeeded in building the core parts of a quantum repeater — a fully functioning network node made with two single matter systems enabling entanglement creation with a photon at the standard frequency of the telecommunications network and entanglement swapping operations. The repeater node consists of two calcium ions captured in an ion trap within an optical resonator as well as single photon conversion to the telecom wavelength. The scientists thus demonstrated the transfer of quantum information over a 50-kilometer-long optical fiber, with the quantum repeater placed exactly halfway between starting and end point. The researchers were also able to calculate which improvements of this design would be necessary to make transmission over 800 kilometers possible which would allow to connect Innsbruck to Vienna.

The current results were published in Physical Review Letters. Funding for the research was provided by a START award from the Austrian Science Fund FWF, the Austrian Academy of Sciences and the European Union, among others. Lanyon’s team is part of the Quantum Internet Alliance, an international project under the EU Quantum Flagship.

The extensive survey of people using Ashley Madison, a website for facilitating extramarital affairs, challenges widely held notions about infidelity, particularly about cheaters’ motivations and experiences. The work is newly published in the journal Archives of Sexual Behavior.

“In popular media, television shows and movies and books, people who have affairs have this intense moral guilt and we don’t see that in this sample of participants,” said lead author Dylan Selterman, an associate teaching professor in Johns Hopkins University’s Department of Psychological & Brain Sciences who studies relationships and attraction. “Ratings for satisfaction with affairs was high — sexual satisfaction and emotional satisfaction. And feelings of regret were low. These findings paint a more complicated picture of infidelity compared to what we thought we knew.”

Researchers conducted this study to better understand the psychological experiences of those who seek and engage in extramarital affairs. Working with researchers at the University of Western Ontario, Selterman surveyed nearly 2,000 active users of Ashley Madison, before and after they had affairs.

Participants were asked about the state of their marriage, about why they wanted to have an affair, and about their general well-being. Respondents, generally middle aged and male, reported high levels of love for their partners, yet low levels of sexual satisfaction.

Participants reported high levels of love for their spouses, yet about half of the participants said that they were not sexually active with their partners. Sexual dissatisfaction was the top-cited motivation to have an affair, with other motivations including the desire for independence and for sexual variety. Fundamental problems with the relationship, like lack of love or anger toward a spouse were among the least-cited reasons for wanting to cheat.

Having great marriages didn’t make cheaters any more likely to regret affairs, the survey found. Participants generally reported that their affair was highly satisfying both sexually and emotionally, and that they did not regret having it.

The results suggest that infidelity isn’t necessarily the result of a deeper problem in the relationship, Selterman said. Participants sought affairs because they wanted novel, exciting sexual experiences, or sometimes because they didn’t feel a strong commitment to their partners, rather than because of a need for emotional fulfillment, the report found.

“People have a diversity of motivations to cheat,” Selterman said. “Sometimes they’ll cheat even if their relationships are pretty good. We don’t see solid evidence here that people’s affairs are associated with lower relationship quality or lower life satisfaction.”

Selterman hopes to advance this work by looking closer at how other populations of cheaters compare to the Ashley Madison population.

“The take-home point for me is that maintaining monogamy or sexual exclusivity especially across people’s lifespans is really, really hard and I think people take monogamy for granted when they’re committed to someone in a marriage. People just assume that their partners are going to be totally satisfied having sex with one person for the next 50 years of their lives but a lot of people fail at it. It doesn’t mean everyone’s relationship is doomed, it means that cheating might be a common part of people’s relationships.”

The blueprint of all organisms is encoded in their DNA. This includes the genes that encode the proteins and determine an organism’s inherent characteristics. In addition, there are other important sections of the DNA, in particular the regions that control the regulation of genes, i.e. when, under which conditions and to what extent the genes are activated.

Compared to the genes, however, these regulatory regions — also known as “cis elements” — are difficult to find. It is changes in precisely these DNA elements that are largely responsible for the differences between organisms, though — and thus also between different plant varieties.

In the past few decades, researchers have discovered that the regulatory regions are the binding sites of specific proteins. Known as transcription factors, it is these that determine when and for how long genes are activated.

Co-corresponding author Dr Thomas Hartwig, who heads the Crop Yield research group at HHU’s Institute for Molecular Physiology and the Max Planck Institute for Plant Breeding Research (MPIPZ) in Cologne: “Finding the few variations that are key to changing traits such as pest resistance among the millions and millions of non-causative genome differences is the ultimate search for a needle in a haystack.”

“Unlike protein-coding genes, regulatory sites usually cannot be identified based on the sequence alone. This makes them very difficult to pinpoint. Our method uses hybrid plants to measure the direct effects of variation in DNA sequence on transcription factor binding,” says lead author Professor Dr Zhi-Yong Wang from the Carnegie Institution for Science.

The study was developed in a cooperation with researchers from the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) in Gatersleben as well as the University of Nebraska-Lincoln and Iowa State University in the USA.

Using hybrids, i.e. the first generation of plants created by crossbreeding two varieties, the research team can compare which regulatory regions differ across the entire genome. Co-author Dr Julia Engelhorn: “Our analytical method allows us to measure precisely whether transcription factors bind more to the maternal or paternal genome.” This procedure has also enabled the team to identify thousands of differences associated with traits, such as yield and pest resistance in maize.

The technology was demonstrated for a transcription factor in the brassinosteroid pathway, a hormone related to growth and disease. Institute director Professor Dr Wolf B. Frommer: “The team has identified thousands of genomic variations that can explain why one variety of maize behaves differently in terms of its yield or resistance to disease. Moreover, the team was able to show that these differences are almost equally genetic and epigenetic.” The latter describes processes that influence gene activity without being encoded in the DNA sequence itself.

One central result of the study is a list of more than 6,000 genome regions that can be targeted for plant breeding. These may include, regions through which positive traits are expressed in certain maize varieties that others plants lack.

Hartwig: “Knowing where in the genome modern breeding methods can be applied to transfer characteristics from certain varieties to others is of great importance to biotechnology. Our study may serve as a guide on how to find these interesting genome regions.” Professor Frommer adds: “The study findings lay the foundation for using modern techniques to cultivate new varieties of maize by skilfully combining the optimal variants.”

The study received funding through the CEPLAS Cluster of Excellence at HHU, the German Research Foundation (DFG), the Carnegie Institution for Science, the Alexander von Humboldt Professor Wolf B. Frommer, the US National Institutes of Health, and the Ministry of Economic Affairs, Tourism, Agriculture and Forestry of Saxony-Anhalt.

Good root growth ensures that plants can absorb sufficient nutrients and grow, thus contributing to their general fitness. To do that, they must align the available resources from metabolic processes with their genetic development programmes. Plants bind carbon dioxide (CO₂) from the atmosphere in their leaves and convert it to simple sugars via photosynthesis. In the form of fructose and glucose, these simple sugars are also allocated in the roots, where they drive the growth and development of the plant.

Prof. Maizel’s team used the thale cress Arabidopsis thaliana, a model plant in plant research, to study how this process occurs at the molecular level. Their investigations focus on what role glucose plays in forming lateral roots. “We do know that, besides plant hormones, sugar from the shoot is also allocated in the roots, but how the plant recognises that sugar resources are available for forming lateral roots has not been understood thus far,” explains Dr Michael Stitz, a researcher on Alexis Maizel’s team.

The studies at the metabolism level showed that Arabidopsis forms lateral roots only when glucose breaks down and carbohydrates are consumed in the pericycle — the outermost cell layer of the main root cylinder. This process is controlled at the molecular level by the target of rapamycin protein. This factor controls critical signal networks and metabolic processes in plants as well as in animals and humans. Its activity is governed by the interaction of growth factors like the plant hormone auxin and nutrients like sugar.

Using Arabidopsis, the researchers discovered that TOR becomes active in the pericycle cells only when sugar is present there. So-called founder cells then form the lateral roots through cell division. Prof. Maizel: “TOR assumes a kind of gatekeeper role; when the plant activates the genetic growth programme responsible for root formation via the hormone auxin, TOR checks whether there are sufficient sugar resources available for this process.” TOR acts by controlling the translation of specific auxin-dependent genes, blocking their expression if there aren’t sufficient sugar resources available. When the researchers suppressed TOR activity, no lateral roots were formed. “That suggests that a fundamental molecular mechanism is involved,” states the Heidelberg plant biologist.

At the same time, the researchers demonstrated that TOR controls, via a similar mechanism, the formation of roots from other plant tissues — the so-called adventitious roots. According to Prof. Maizel, the results from their investigations could also be of interest for agricultural applications. “They could potentially be used to develop new strategies for plant growth optimised for various environmental conditions and better crop yields,” emphasises the researcher.

The research was funded by the German Research Foundation. In addition to the plant biologists from the Centre for Organismal Studies of Heidelberg University, researchers from the University of Strasbourg (France), the Max Planck Institute of Molecular Plant Physiology in Potsdam, the Centre for Research in Agricultural Genomics in Barcelona (Spain), and University College Cork (Ireland) also contributed. The results of their research were published in The EMBO Journal.