18 research outputs found
Perturbing exactly tri-bimaximal neutrino mixings with charged lepton mass matrices
We study perturbations of exactly tri-bimaximal neutrino mixings under the
assumption that they are coming solely from the charged lepton mass matrix.
This may be plausible in scenarios where the mass generation mechanisms of
neutrinos and charged leptons/quarks have a different origin. As a working
hypothesis, we assume mass textures which may be generated by the
Froggatt-Nielsen mechanism for the charged lepton and quark sectors, which
generically leads to strong hierarchies, whereas the neutrino sector is exactly
tri-bimaximal with a mild (normal) hierarchy. We find that in this approach,
deviations from maximal atmospheric mixing can be introduced without affecting
theta_13 and theta_12, whereas a deviation of theta_13 or theta_12 from its
tri-bimaximal value will inevitably lead to a similar-sized deviation of the
other parameter. Therefore, the already very precise knowledge of theta_12
points towards small sin^2(2 theta_13) <= 0.01. The magnitude of this deviation
can be controlled by the specific form of the charged lepton texture.Comment: 13 pages, 9 figures; matches published version, changes in notatio
Stand growth and structure of mixed-species and monospecific stands of Scots pine (Pinus sylvestris L.) and oak (Q. robur L., Quercus petraea (Matt.) Liebl.) analysed along a productivity gradient through Europe
19 PĂĄg.Past failures of monocultures, caused by wind-throw or insect damages, and ongoing climate change currently strongly stimulate research into mixed-species stands. So far, the focus has mainly been on combinations of species with obvious complementary functional traits. However, for any generalization, a broad overview of the mixing reactions of functionally different tree species in different mixing proportions, patterns and under different site conditions is needed, including assemblages of species with rather similar demands on resources such as light. Here, we studied the growth of Scots pine and oak in mixed versus monospecific stands on 36 triplets located along a productivity gradient across Europe, reaching from Sweden to Spain and from France to Georgia. The set-up represents a wide variation in precipitation (456â1250 mm yearâ1), mean annual temperature (6.7â11.5 °C) and drought index by de Martonne (21â63 mm °Câ1). Stand inventories and increment cores of trees stemming from 40- to 132-year-old, fully stocked stands on 0.04â0.94-ha-sized plots provided insight into how species mixing modifies stand growth and structure compared with neighbouring monospecific stands. On average, the standing stem volume was 436 and 360 m3 haâ1 in the monocultures of Scots pine and oak, respectively, and 418 m3 haâ1 in the mixed stands. The corresponding periodical annual volume increment amounted to 10.5 and 9.1 m3 haâ1 yearâ1 in the monocultures and 10.5 m3 haâ1 yearâ1 in the mixed stands. Scots pine showed a 10% larger quadratic mean diameter (p < 0.05), a 7% larger dominant diameter (p < 0.01) and a 9% higher growth of basal area and volume in mixed stands compared with neighbouring monocultures. For Scots pine, the productivity advantages of growing in mixture increased with site index (p < 0.01) and water supply (p < 0.01), while for oak they decreased with site index (p < 0.01). In total, the superior productivity of mixed stands compared to monocultures increased with water supply (p < 0.10). Based on 7843 measured crowns, we found that in mixture both species, but especially oak, had significantly wider crowns (p < 0.001) than in monocultures. On average, we found relatively small effects of species mixing on stand growth and structure. Scots pine benefiting on rich, and oak on poor sites, allows for a mixture that is productive and most likely climate resistant all along a wide ecological gradient. We discuss the potential of this mixture in view of climate change.The authors wish to thank the European Union for funding the project ?Mixed species forest management. Lowering risk, increasing resilience (REFORM)? (#2816ERA02S, PCIN2017-026) under the framework of Sumforest ERA-NET. All contributors thank their national funding institutions to establish, measure and analyse data from the triplets. The first author also thanks the Bayerische Staatsforsten (BaySF) for supporting the establishment of the plots and the Bavarian State Ministry for Nutrition, Agriculture, and Forestry for permanent support of the project W 07 ?Long-term experimental plots for forest growth and yield research? (#7831-22209-2013). The French site (FR-1) belongs to the OPTMix experimental site (https://optmix.irstea.fr), which is supported annually by Ecofor, Allenvi, and the French national research infrastructure ANAEE-F. Research on the Lithuanian triplets was made possible by the national funding institution Research Council of Lithuania (LMTLT), agreement No. S-SUMFOREST-17-1. Thanks are also due to Ulrich Kern for the graphical artwork. Finally, we thank two anonymous reviewers for their constructive criticism.Peer reviewe
Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches
Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly
Selenium biochemistry and its role for human health
Despite its very low level in humans, selenium plays an important and unique role among the (semi)metal trace essential elements because it is the only one for which incorporation into proteins is genetically encoded, as the constitutive part of the 21st amino acid, selenocysteine. Twenty-five selenoproteins have been identified so far in the human proteome. The biological functions of some of them are still unknown, whereas for others there is evidence for a role in antioxidant defence, redox state regulation and a wide variety of specific metabolic pathways. In relation to these functions, the selenoproteins emerged in recent years as possible biomarkers of several diseases such as diabetes and several forms of cancer. Comprehension of the selenium biochemical pathways under normal physiological conditions is therefore an important requisite to elucidate its preventing/therapeutic effect for human diseases. This review summarizes the most recent findings on the biochemistry of active selenium species in humans, and addresses the latest evidence on the link between selenium intake, selenoproteins functionality and beneficial health effects. Primary emphasis is given to the interpretation of biochemical mechanisms rather than epidemiological/observational data. In this context, the review includes the following sections: (1) brief introduction; (2) general nutritional aspects of selenium; (3) global view of selenium metabolic routes; (4) detailed characterization of all human selenoproteins; (5) detailed discussion of the relation between selenoproteins and a variety of human diseases
Adaption of the Col-CC Integrated Management System to the new MPLS network
The Integrated Management System (IMS) in the Columbus Control Center (Col-CC) is software capable of monitoring and commanding almost all of the subsystems of the complex
Columbus Ground Segment. One of the subsystems monitored is the IGS network (Interconnection Ground Subnetwork). This network provides the basis for communication between Col-CC and its international partners (NASA, ESA, ATV-CC, etc.) and all user support and operations centers (USOCs) across Europe. The IGS network was originally designed to use ATM technology, but due to cost reductions many centers were connected via ISDN. Since last year the ATM and ISDN technology was replaced by a MPLS (Multiprotocol Label Switching) network. The migration from ATM/ISDN to MPLS implies a lot of configuration and testing work within the Integrated Management System (IMS) in parallel to real-time operations. In the ATM/ISDN network the IMS was configured to
monitor the ATM/ISDN connections and to start/stop the ISDN lines towards the remote user centers (USOCs) in order to maintain the costs under control. In the MPLS network the
main focus is on monitoring the IGS network since start/stop of connections is not necessary anymore. The paper deals with the changes in the monitoring and commanding approach
and the comparison of the different monitoring issues. Focus is on the subsystems of Col-CC, which were affected by the MPLS migration: The IGS network itself (including the WAN
monitoring), the Voice System (VoCS) and the Video System (MVDS)
RICADOS - Rendezvous, Inspection, Capturing and Detumbling by Orbital Servicing
The paper presents a system called RICADOS (=Rendezvous, Inspection, CApturing and Detumbling by Orbital Servicing), a new on-board inspection, rendezvous and robotic system for on-orbit servicing (OOS) and a ground system for operating servicing missions including telepresence tasks. The RICADOS system provides robust and reliable inspection, guidance, navigation and control functionality to approach a target satellite in its orbit, and a robotic sub-system for final capturing and detumbling / stabilization of the target. Further, the RICADOS system does not only consist of the OOS payload. For simulation of the space segment two robotic hardware-in-the-loop test facilities are used: the European Proximity Operations Simulator (EPOS) 2.0 and the On-Orbit Servicing Simulator (OOS-Sim). It includes further a satellite simulator where i.a. the orbital and attitude dynamics are computed. RICADOS also simulates the communication path between space and ground and it contains a ground segment, which equals the ground segment of real missions, such that the operating team can perform tests and trainings from real consoles at the control center. Especially, the most critical phases of such a mission, the final close range approach, the capturing process and the stabilization can be tested within a very realistic environment
Role of Relative Humidity in the Secondary Organic Aerosol Formation from High-NOx Photooxidation of Long-Chain Alkanes: n-Dodecane Case Study
The role of relative humidity (RH) in secondary organic aerosol (SOA) formation from high-NOx photooxidation of long-chain alkanes was investigated by performing simulation chamber experiments on n-dodecane (C12H26). This molecule was chosen as a model compound for the class of long-chain alkanes. The experiments span a wide range of RH conditions from = 5%) conditions. Measurements of major oxidation products in the gaseous and aerosol phases revealed the effect of water on a series of multiphasic reaction mechanisms and SOA production. Under very low RH, an acid-catalyzed "dehydration" reaction of polyfunctional molecules leads to lower volatility products. This pathway was found to be inhibited from dry to ambient RH conditions, explaining the SOA yield reduction. In addition to the previously established carbonyls and hydroxycarbonyls, novel tracers, that is, lactone and carboxylic acid, were identified using authentic standards, providing evidence for water-sensitive multiphasic pathways. Among the species formed via the dehydration channel, we find not only volatile species but also very reactive intermediates (e.g., dihydrofurans) which partition back to the gas phase. Owing to its double bond, it can be further oxidized to lower volatility secondary products, which forms a complex multiphasic scheme involving many condensation reaction-evaporation steps
The OCAPI collaborative platform: study of two particle pollution episodes in 2016 in Paris
Air pollution and its impacts are subject to an expanded interest since the middle of the 20th century, especially in urban areas which gathered an important part of emission sources. These polluted urban air masses are composed by a complex mixture of gases and aerosols coming from various emission sources (vehicular traffic, industries, residential heating, agricultural activities, natural sources) or chemical processes. To efficiently reduce this pollution and its impacts on population, it is important to understand its drivers, its sources and its impact on human health. To get some insights in Paris air pollution, a collaborative measurement platform called OCAPI (âObservation de la Composition AtmosphĂ©rique Parisienne de lâIPSLâ) has been built and implies several Parisian research laboratories of IPSL institute (CEREA, LSCE, LMD, LISA, LATMOS, LERMA and METIS) as well as public agencies and institutes in charge of Paris air pollution monitoring (AIRPARIF, INERIS). OCAPI platform aims at gathering skills and instruments of these laboratories to measure the composition and dynamics of Paris atmosphere. In this framework, multi-site measurements were performed during two intense particle pollution episodes which occurred in March 2016 and between November and December 2016. These two episodes were characterized by different meteorological conditions and different type of emission sources. Indeed, March episode was related to intense agricultural activities and high ammonium nitrate contribution to aerosol composition; while end of year episode was related to low wind speed, cold conditions and thin boundary layer which favoured the stagnation of locally emitted pollutants. This latter episode was characterized by large contribution of organics in aerosol composition. In this presentation, a study of these two episodes will be presented. We will first present the context and the OCAPI platform. Then, first results of dynamics and aerosol composition measurements will be shown to discuss the drivers of these two episodes. Finally conclusions will be drawn and perspectives will be given by presenting the objectives of the forthcoming EPPI project which will deal with the OCAPI platform measurement device
Evidence for a role of epithelial mesenchymal transition during pathogenesis of fistulae in Crohn's disease
BACKGROUND: The pathogenesis of fistulae in Crohn's disease (CD) patients is barely understood. We recently showed that more than two-thirds of CD fistulae are covered with flat, mesenchymal-like cells (transitional cells [TC]) forming a patchy basement membrane. Epithelial-to-mesenchymal transition (EMT) is a process of reprogramming epithelial cells, allowing them to migrate more effectively and giving epithelial cells an "invasive" potential. EMT has been suggested to be crucial in fibrosis found in different tissues and diseases. We therefore investigated whether EMT could be involved in the pathogenesis of fistulae formation in CD. METHODS: In all, 18 perianal fistulae, 2 enteroenteric, and 1 enterovesical fistulae from 17 CD patients were analyzed. In addition 2 perianal fistulae of non-CD patients were studied. Hematoxylin and eosin staining, immunohistochemistry for the expression of cytokeratins 8 and 20, beta6-integrin, E-cadherin, beta-catenin, vimentin, and TGF-beta1 and 2 were performed according to standard techniques. RESULTS: The TC covering perianal or enteroenteric fistulae were strongly positive for cytokeratins 8 and 20 but negative for vimentin, indicating their epithelial origin. beta6-Integrin and TGF-beta had the highest staining intensities in the transitional zone between the epithelium and the TC. Expression of junctional proteins such as E-cadherin was reduced in TC as compared to regular fistulae epithelium. In addition, a translocation of beta-catenin from the membrane to the cytoplasm was observed. CONCLUSIONS: Our data for the first time indicate an expression pattern of epithelial and mesenchymal markers in TC associated with fistulae formation that is characteristic for EMT. Studying the pathways of EMT during intestinal fistulae formation may help to develop new therapeutic strategies
Croissance et structure des peuplements mixtes et monospĂ©cifiques de pin sylvestre (Pinus sylvestris L.) et de chĂȘne sessile (Quercus petraea (Matt.) Liebl.). Analyses le long d'un gradient de productivitĂ© en Europe
International audiencePast failures of monocultures, caused by wind-throw or insect damages, and ongoing climate change currently strongly stimulate research into mixed-species stands. So far, the focus has mainly been on combinations of species with obvious complementary functional traits. However, for any generalization, a broad overview of the mixing reactions of functionally different tree species in different mixing proportions, patterns and under different site conditions is needed, including assemblages of species with rather similar demands on resources such as light. Here, we studied the growth of Scots pine and oak in mixed versus monospecific stands on 36 triplets located along a productivity gradient across Europe, reaching from Sweden to Spain and from France to Georgia. The set-up represents a wide variation in precipitation (456-1250 mm year-1), mean annual temperature (6.7-11.5 °C) and drought index by de Martonne (21-63 mm °C-1). Stand inventories and increment cores of trees stemming from 40- to 132-year-old, fully stocked stands on 0.04-0.94-ha-sized plots provided insight into how species mixing modifies stand growth and structure compared with neighbouring monospecific stands. On average, the standing stem volume was 436 and 360 m3 ha-1 in the monocultures of Scots pine and oak, respectively, and 418 m3 ha-1 in the mixed stands. The corresponding periodical annual volume increment amounted to 10.5 and 9.1 m3 ha-1 year-1 in the monocultures and 10.5 m3 ha-1 year-1 in the mixed stands. Scots pine showed a 10% larger quadratic mean diameter (pâis smaller thanâ0.05), a 7% larger dominant diameter (pâis smaller thanâ0.01) and a 9% higher growth of basal area and volume in mixed stands compared with neighbouring monocultures. For Scots pine, the productivity advantages of growing in mixture increased with site index (pâis smaller thanâ0.01) and water supply (pâis smaller thanâ0.01), while for oak they decreased with site index (pâis smaller thanâ0.01). In total, the superior productivity of mixed stands compared to monocultures increased with water supply (pâis smaller thanâ0.10). Based on 7843 measured crowns, we found that in mixture both species, but especially oak, had significantly wider crowns (p is smaller thanâ0.001) than in monocultures. On average, we found relatively small effects of species mixing on stand growth and structure. Scots pine benefiting on rich, and oak on poor sites, allows for a mixture that is productive and most likely climate resistant all along a wide ecological gradient. We discuss the potential of this mixture in view of climate change