It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Saturday, June 19, 2021
Wind and waves: A step toward better control of heavy-lift crane vessels
Massive heavy-lift crane vessels, capable of hauling thousands of tons, navigate the rough waves and strong winds offshore to construct wind turbines and oil fields in the ocean. An international team of researchers has developed a new modeling system to help improve the control, and ultimately the safety, of such vessels. They published their approach in the April issue in IEEE/CAA Journal of Automatica Sinica.
"Dynamic positioning allows the ship to stay fixed in a certain location, by acting on the thruster," said paper author Simone Baldi, professor in the School of Mathematics and School of Cyber Science and Engineering, Southeast University in China, and guest with the Delft Center for System and Control, Delft University of Technology in the Netherlands.
This positioning operation acts as a counterbalance. The thruster applies equal force in the opposite direction of the wind or wave that attempts to dislodge the ship.
"However, it sometimes happens that the dynamic positioning does not cope with such changes, leading the ship to oscillate instead of remaining fixed in one spot," Baldi said. "Our approach allows the dynamic positioning to be robust in challenging sea conditions with large waves."
To help the vessels safely work in rough conditions, Baldi and his team augmented the dynamic positioning model system with a digital observer that can translate wind or wave disturbances into specific measurements that reflect position and velocity.
Baldi noted that other proposed models also include observers, but, he said, those observer designs typically depend on vessels responding quickly to measured disturbances -- which is often impossible due to the sheer size of the thrusters and propellers.
To address this challenge, the researchers incorporated known variables, such as the strength of the lines and thrust holding the ship to the construction site, and worst-case scenario ranges for unknown variables, such as wind and waves. The researchers then applied an observer-controller composite that converts motion into measurements to inform operation directions while also allowing the vessel to respond in a reasonable timeframe. The design is guided by key performance indicators while considering the worst-case uncertainty scenarios.
"Currently, we have tested our method in a realistic simulation, which is only a first step," Baldi said.
Next, Baldi said, the researchers hope to test the proposed solution on a small-scale ship under controlled conditions before moving on to tests on heavy-lift crane vessels in the sea.
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J. Ye, S. Roy, M. Godjevac, V. Reppa, and S. Baldi, "Robustifying dynamic positioning of crane vessels for heavy lifting operation," IEEE/CAA J. Autom. Sinica, vol. 8, no. 4, pp. 753-765, Apr. 2021.
IEEE/CAA Journal of Automatica Sinica aims to publish high-quality, high-interest, far-reaching research achievements globally, and provide an international forum for the presentation of original ideas and recent results related to all aspects of automation.
The first Impact Factor of IEEE/CAA Journal of Automatica Sinica is 5.129, ranking among Top 17% (11/63, SCI Q1) in the category of Automation & Control Systems, according to the latest Journal Citation Reports released by Clarivate Analytics in 2020. In addition, its latest CiteScore is 11.2, and has entered Q1 in all three categories it belongs to (Information System, Control and Systems Engineering, Artificial Intelligence) since 2018.
VIDEO: FOOTPRINTS FROM AT LEAST SIX DIFFERENT SPECIES OF DINOSAUR -- THE VERY LAST DINOSAURS TO WALK ON UK SOIL 110 MILLION YEARS AGO -- HAVE BEEN FOUND IN KENT, A... view more
CREDIT: UNIVERSITY OF PORTSMOUTH
Footprints from at least six different species of dinosaur - the very last dinosaurs to walk on UK soil 110 million years ago - have been found in Kent, a new report has announced.
The discovery of dinosaur footprints by a curator from Hastings Museum and Art Gallery and a scientist from the University of Portsmouth is the last record of dinosaurs in Britain.
The footprints were discovered in the cliffs and on the foreshore in Folkestone, Kent, where stormy conditions affect the cliff and coastal waters, and are constantly revealing new fossils.
Professor of Palaeobiology, David Martill, said: "This is the first time dinosaur footprints have been found in strata known as the 'Folkestone Formation' and it's quite an extraordinary discovery because these dinosaurs would have been the last to roam in this country before becoming extinct.
"They were walking around close to where the White Cliffs of Dover are now - next time you're on a ferry and you see those magnificent cliffs just imagine that!"
The footprint fossils formed by sediment filling the impression left behind when a dinosaur's foot pushes into the ground, which then preserves it.
The footprints are from a variety of dinosaurs, which shows there was a relatively high diversity of dinosaurs in southern England at the end of the Early Cretaceous period, 110 million years ago.
They are thought to be from ankylosaurs, rugged-looking armoured dinosaurs which were like living tanks; theropods, three-toed flesh-eating dinosaurs like the Tyrannosaurus rex; and ornithopods, plant-eating 'bird-hipped' dinosaurs so-called because of their pelvic structure being a little bit similar to birds.
Philip Hadland, Collections and Engagement Curator at the Hastings Museum and Art Gallery is lead author on the paper. He said: "Back in 2011, I came across unusual impressions in the rock formation at Folkestone. They seemed to be repeating and all I could think was they might be footprints.
"This was at odds with what most geologists say about the rocks here, but I went looking for more footprints and as the tides revealed more by erosion, I found even better ones. More work was needed to convince the scientific community of their validity, so I teamed up with experts at the University of Portsmouth to verify what I'd found."
Most of the findings are isolated footprints, but one discovery comprises six footprints - making a 'trackway', which is more than one consecutive print from the same animal.
This trackway of prints are similar in size to an elephant footprint and have been identified as likely to be an Ornithopodichnus, of which similar, but smaller-sized footprints have also been found in China from the same time period.
The largest footprint found - measuring 80 cm in width and 65 cm in length - has been identified as belonging to an Iguanodon-like dinosaur. Iguanodons were also plant-eaters, grew up to 10 metres long and walked on both two legs or on all fours.
Professor Martill said: "To find such an array of species in one place is fascinating. These dinosaurs probably took advantage of the tidal exposures on coastal foreshores, perhaps foraging for food or taking advantage of clear migration routes."
In the Late Cretaceous period, this part of Kent, and indeed much of the United Kingdom was beneath a shallow sea, but this study also shows unequivocally that the Folkestone Formation was inter-tidal.
Mr Hadland said: "Aside from finding that dinosaurs went to the seaside just like their modern relatives the birds, we have also found new evidence that changes the interpretation of the geology of the Folkestone Formation strata.
"It just goes to show that what has been previously published about the geology of an area isn't always correct and new insights can be made. There is also the potential for almost anyone to make a discovery that adds to scientific knowledge from publicly accessible geological sites."
The paper is published in Proceedings of the Geologists' Association and some of the footprints are currently on display at Folkestone Museum.
CAPTION
A palaeoartist's impression of the dinosaurs and their footprints.
CREDIT
Megan Jacobs, University of Portsmouth
POPULAR SCIENCE
Research supports protestors' concerns about the future of Llobregat Delta, in Barcelona
New study by the ICTA-UAB shows that residents and visitors highlight the natural and biodiversity values of the Llobregat Delta, in Barcelona
New study by the ICTA-UAB shows that residents and visitors highlight the natural and biodiversity values of the Llobregat Delta, in Barcelona.
A new study undertaken by researchers at the Institute of Environmental Science and Technology of the Universitat Autònoma de Barcelona (ICTA-UAB) supports protestors' concerns about damage to the Llobregat Delta in airport expansion plans.
The research, carried out in 2019, found that the well-maintained and unique natural environment of the Llobregat Delta is important or very important to 100% residents and 98.8% of visitors who responded to the survey.
The recently published article in Environmental Science and Policy found that the greatest frustrations that residents and visitors expressed related to the expansion of the airport and urban areas. Participants surveyed expressed concern about future airport expansion plans, and expressed their desire that these plans be modified.
"What is remarkable about the results is the amount of agreement among residents and visitors about the importance of the natural values of the Llobregat Delta. Even though the airport is nearby, people value being able to be able to access a protected natural area so close to Barcelona", explains Dr Sonia Graham, the researcher leading the project. Dr Graham recalls that, "during the interviews, a Barcelona resident told researchers that they would not like the airport to grow larger, and to have an impact on the area. They stated that the impact on the beach area by a possible expansion would be quite a hard blow, horrific". The wetlands, birdwatching huts and walking paths are highly valued ecosystem services and infrastructure that enable residents and visitors to experience and appreciate this unique area.
Beatrice Meo, the lead author of the article, explains that not only are people concerned about the expansion of the airport, they are also worried about the impacts of climate change. "About 90% of residents and visitors are very or fairly concerned about the impacts of climate change on the Llobregat Delta. More than 60% of respondents believe we are already feeling the effects of climate change now", she says.
The work took place between March and June 2019. It involved in-depth interviews and a survey of residents and visitors to the Llobregat Delta. The interviews and survey collected data on what residents and visitors value about the natural environment, and how concerned they are about the impacts of climate change on the delta.
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Separating natural and man-made pollutants in the air
What COVID-19's lockdown to prevent infection taught us
IMAGE: (A) DOMINANT LAND COVER TYPES IN THE STUDY DOMAIN (74°E, 27°N--80°E, 30°N) ARE URBAN AREAS, CROPLANDS AND DESERT SHRUBLANDS. (B) TIMELINE OF LOCKDOWN POLICIES, WHERE BAU REFERS TO BUSINESS-AS-USUAL CONDITIONS... view more
CREDIT: MISRA P. ET AL., 2021, SCIENTIFIC REPORTS, SPRINGER NATURE DOI.ORG/10.1038/S41598-021-87673-2
COVID-19 has changed the world in unimaginable ways. Some have even been positive, with new vaccines developed in record time. Even the extraordinary lockdowns, which have had severe effects on movement and commerce, have had beneficial effects on the environment and therefore, ironically, on health. Studies from all around the world, including China, Europe and India, have found major drops in the level of air pollution. However, to fully understand the impact of anthropogenic causes, it is important to separate them from natural events in the atmosphere like wind flow.
To demonstrate this point, a new study by researchers at the Research Institute for Humanity and Nature, Japan, uses satellite data and mathematical modeling to explain just how great the lockdown effect on nitrogen oxides has been in Delhi, India, one of the world's most polluted cities, and its surrounding area. This study was carried out under the activity named "Mission DELHIS (Detection of Emission Change of air pollutants: Human Impact Studies)" as a part of RIHN project, Aakash (meaning "Sky" in Hindi, originated from sanskrit) (https://www.chikyu.ac.jp/rihn_e/covid-19/topics.html#topics6).
"Nitrogen oxides are good chemical tracers for testing model hypothesis, because besides their health effects, they have a short lifetime. Therefore, it is unlikely wind will bring nitrogen oxides from far away." explains Professor Sachiko Hayashida, who led the study.
Nitrogen oxides naturally change due to dynamic and photochemical conditions in the atmosphere, and are emitted from the Earth's surface by both natural and anthropogenic activities. Therefore, Hayashida argues, looking simply at their concentration levels in the atmosphere provides only a crude impression of man-made contributions.
"COVID-19 pandemic has given us an opportunity of social experiment, when we can discriminate the anthropogenic effects on nitrogen oxides from the natural ones caused by atmospheric conditions and natural emissions, because only anthropogenic emissions decreased due to the lockdown. These confounders affect policy to control air quality" she says.
Strict lockdown was enforced in Delhi for two months in 2020, from the end of March to the end of May. This period coincides with the transition in atmospheric conditions, such as actinic flux, from low in spring to high in early summer, and also from stagnant winds to high ventilation across the entire northern India region.
The researchers analyzed seasonal and inter-annual changes using multi-year satellite data to predict what the levels would be had there been no lockdown. They estimated top-down emissions using a steady-state continuity equation. The study's findings clearly show that the natural conditions could not explain the dramatic drop in 2020 nitrogen oxide levels. Not even close.
"Our calculations suggested that 72% of nitrogen oxides emissions in urban centres are the resulted solely from traffic and factories," said Hayashida.
Interestingly, the levels recovered after the lockdown more quickly in rural levels than they did in urban ones, an effect attributed to agricultural activities, such as crop-residue burning, which resumed almost immediately. Unlike factories, the agricultural activities continued, albeit at a lesser pace, during the lockdown, which was less stringent on agriculture.
Hayashida says that her team's approach should have an impact on how we study harmful chemical species emitted to the atmosphere.
"Our findings show the importance of analyzing top-down emissions and not just atmospheric concentrations. We expect our approach to guide effective policy on air pollution," she said.
CAPTION
Mean top-down NOx emission in 2020 during (a) BAU (business-as-usual), and subsequent lockdown-phases (b)-(f).
CREDIT
Misra P. et al., 2021, Scientific Reports, Springer Nature doi.org/10.1038/s41598-021-87673-2
RA is an inflammatory autoimmune disease that causes pain, swelling and stiffness in the joints. It can also cause fatigue, and the underlying inflammation may affect other body systems. It is more common in women than in men. To date, active smoking has been the most reproducibly reported risk factor for a type of RA called anti-citrullinated protein antibody (ACPA) positive RA-particularly in people who carry the HLA-DRB1-shared epitope alleles.
Nguyen and colleagues set out to investigate the relationship between passive smoking and the risk of developing RA in a large prospective cohort of healthy French women.
79,806 women were included in the study. Among them, 698 cases of RA were identified. In the whole cohort, 10,810 (13.5%) were exposed to passive smoking as children, and 42,807 (53.6%) to passive smoking as adults.6,581 (8.25%) were exposed to both, and 47,036 (58.9%) were exposed to either.
In the whole population, passive smoking in childhood was positively associated with the risk of RA. When analysed by each person's own smoking status, passive smoking in childhood was associated with RA among women who had never smoked themselves, but not among those who had ever smoked themselves.
When the authors looked at passive smoking in adulthood, there was also a positive risk association in the whole population. But when analysed again by individual smoking status, the association with increased RA risk was only among never-smoking women, not those who had ever themselves been a smoker.
These results suggest that smoking by-products - whether actively or passively inhaled - could generate autoimmunity, at least towards antigens involved in RA pathogenesis.
In a poster examining another link between the lungs and inflammatory arthritis, Adami and colleagues looked at the association between concentration of air pollutants and biologic drug retention rates in people with chronic inflammatory arthritis (CIA) living in the Verona area of Italy.
This was a case-crossover study to compare the exposure to pollutants in the 30?day and 60-day periods preceding a drug switch or swap due to disease progression.
1,286 patients with CIA (888 with RA, 260 with psoriatic arthritis and 138 with ankylosing spondylitis) were included, and 13,636 daily air pollution records were retrieved. The authors found an exposure-dependent relationship between exposure to air pollutants and markers of inflammation in people with CIA. Exposures of greater than 50μg/m3 and greater than 40μg/m3 had a 150% and 65% higher risk of having C-reactive protein (CRP) levels above 5 mg/L, respectively.
If the pollution threshold was set at 30μg/m3(below the European Union health protection limit) there was still a 38% higher risk of having altered CRP (OR 1.383, 95% CI 1.206-1.588).
Air pollutants concentrations were higher before a switch or swap due to drug inefficacy. The authors concluded that environmental air pollution was a determinant of poor response to biologic treatment. Interventions to decrease fossil fuel combustion emissions might have beneficial effects on the persistence rate of biologic treatments in people with inflammatory arthritis.
HOUSTON - (June 18, 2021) - To boost employees' creativity, managers should consider offering a set of rewards for them to choose from, according to a new study by management experts at Rice University, Tulane University, the University of North Carolina at Greensboro and National Taiwan Normal University.
The study, co-authored by Jing Zhou, the Mary Gibbs Jones Professor of Management and Psychology at Rice's Jones Graduate School of Business, is the first to systematically examine the effects of reward choice in a field experiment, which was conducted in the context of an organizationwide suggestion program. An advance copy of the paper is published online in the Journal of Applied Psychology.
"Organizations spend a lot of resources and exert a great deal of effort in designing incentive schemes that reward the employees who exhibit creativity at work," Zhou said. "Our results showed that the effort may be a bit misplaced. Instead of discovering one reward type that is particularly effective at promoting creativity, what is more effective is to provide the employees with the opportunity to choose from several reward types, if they submit one or more ideas that are among the top 20% most creative ones."
Workers in the study were given a range of options: a financial reward for the individual employee or their team, a self-discretionary reward such as getting priority to select days off, or a donation the company made to a charity selected by the employee. Those choices had positive, significant effects on the number of creative ideas employees generated and the creativity level of those ideas, Zhou and her co-authors found.
The researchers arrived at their findings by conducting a quasi-experiment at a company in Taiwan over the course of several months. Then they conducted a second experimental study that included employees from 12 organizations in Taiwan to replicate the first study's results and compared the results with a control group.
The studies also found that rewards aimed at helping others, such as making a donation to a charity, might be especially powerful. But for less-creative employees, alternative rewards that benefit those in need might actually lower creativity and should be avoided, the authors said.
The researchers also found that the choice of rewards fostered creativity by raising the employees' belief in their ability to be creative. Alternative rewards also had a powerful impact on boosting the creativity of employees who earlier had scored high on an assessment of creative personality characteristics.
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Zhou co-authored the paper with Greg Oldham of Tulane, Aichia Chuang of the University of North Carolina at Greensboro and Ryan Shuwei Hsu of National Taiwan Normal University.
For a copy of the study, "Enhancing employee creativity: Effects of choice, rewards and personality," email jfalk@rice.edu.
For more information about and insights from Rice Business faculty research, visit the school's Rice Business Wisdom website, https://business.rice.edu/wisdom.
Follow Rice Business via Twitter @Rice_Biz.
Follow Rice News and Media Relations via Twitter @RiceUNews.
IMAGE: THE FLYPOL INSTRUMENT, WHICH WAS USED TO MEASURE BIOSIGNATURES FROM THE AIR, ABOARD THE HELICOPTER. view more
CREDIT: COURTESY OF LUCAS PATTY
Left hands and right hands are almost perfect mirror images of each other. But whatever way they are twisted and turned, they cannot be superimposed onto each other. This is why the left glove simply won't fit the right hand as well as it fits the left. In science, this property is referred to as chirality.
Just like hands are chiral, molecules can be chiral, too. In fact, most molecules in the cells of living organisms, such as DNA, are chiral. Unlike hands, however, that usually come in pairs of left and right, the molecules of life almost exclusively occur in either their "left-handed" or their "right-handed" version. They are homochiral, as researchers say. Why that is, is still not clear. But this molecular homochirality is a characteristic property of life, a so-called biosignature.
As part of the MERMOZ project (see info box), an international team led by the University of Bern and the National Centre of Competence in Research NCCR PlanetS, has now succeeded in detecting this signature from a distance of 2 kilometers and at a velocity of 70 kph. Jonas Kühn, MERMOZ project manager of the University of Bern and co-author of the study that has just been published in the journal Astronomy and Astrophysics, says: "The significant advance is that these measurements have been performed in a platform that was moving, vibrating and that we still detected these biosignatures in a matter of seconds."
An instrument that recognizes living matter
"When light is reflected by biological matter, a part of the light's electromagnetic waves will travel in either clockwise or counterclockwise spirals. This phenomenon is called circular polarization and is caused by the biological matter's homochirality. Similar spirals of light are not produced by abiotic non-living nature", says the first author of the study Lucas Patty, who is a MERMOZ postdoctoral researcher at the University of Bern and member of the NCCR PlanetS,
Measuring this circular polarization, however, is challenging. The signal is quite faint and typically makes up less than one percent of the light that is reflected. To measure it, the team developed a dedicated device called a spectropolarimeter. It consists of a camera equipped with special lenses and receivers capable of separating the circular polarization from the rest of the light.
Yet even with this elaborate device, the new results would have been impossible until recently. "Just 4 years ago, we could detect the signal only from a very close distance, around 20 cm, and needed to observe the same spot for several minutes to do so", as Lucas Patty recalls. But the upgrades to the instrument he and his colleagues made, allow a much faster and stable detection, and the strength of the signature in circular polarisation persists even with distance. This rendered the instrument fit for the first ever aerial circular polarization measurements.
Useful measurements on earth and in space
Using this upgraded instrument, dubbed FlyPol, they demonstrated that within mere seconds of measurements they could differentiate between grass fields, forests and urban areas from a fast moving helicopter. The measurements readily show living matter exhibiting the characteristic polarization signals, while roads, for example, do not show any significant circular polarization signals. With the current setup, they are even capable of detecting signals coming from algae in lakes.
After their successful tests, the scientists now look to go even further. "The next step we hope to take, is to perform similar detections from the International Space Station (ISS), looking down at the Earth. That will allow us to assess the detectability of planetary-scale biosignatures. This step will be decisive to enable the search for life in and beyond our Solar System using polarization", says MERMOZ principal investigator and co-author Brice-Olivier Demory, professor of astrophysics at the University of Bern and member of the NCCR PlanetS says.
The sensitive observation of these circular polarization signals is not only important for future life detection missions. Lucas Patty explains: "Because the signal directly relates to the molecular composition of life and thus its functioning, it can also offer valuable complementary information in Earth remote sensing." It can for instance provide information about deforestation or plant disease. It might even be possible to implement circular polarization in the monitoring of toxic algal blooms, of coral reefs and the effects of acidification thereon.
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Publication details:
C.H. Lucas Patty et. Al., Biosignatures of the Earth I. Airborne spectropolarimetric detection of photosynthetic life, Astronomy & Astrophysicshttps://doi.org/10.1051/0004-6361/202140845
SAINT-EX - Search and characterisation of exoplanets
The SAINT-EX research group (funded by the SNF Professorship of Prof. Brice-Olivier Demory) focuses on the:
-detection of temperate Earth-sized exoplanets (SAINT-EX observatory),
-remote sensing of life in planetary atmospheres/surfaces (MERMOZ),
-instrumentation for non-invasive, in-vivo cancer diagnosis and staging (BrainPol).
The MERMOZ (Monitoring planEtary suRfaces with Modern pOlarimetric characteriZation) project aims to investigate whether we can identify and characterize Earth's life from space, by building a benchmark library of surface feature signatures with remote full-Stokes spectro-polarimetry. In this framework, our planet is considered as a proxy for other solar system bodies and exoplanets.
MERMOZ is a project in partnership between the Universities of Bern, Leiden and Delft (NL).
The project's feasibility study is funded by the Centre for Space and Habitability (CSH) and the NCCR PlanetS.
In 2014, the Swiss National Science Foundation awarded the University of Bern the National Centre for Competence in Research (NCCR) PlanetS, which it manages together with the University of Geneva.
Since its involvement in the first moon landing in 1969, the University of Bern has been participating in space missions of the major space organizations, such as ESA, NASA, ROSCOSMOS and JAXA. It is currently co-leading the European Space Agency's (ESA) CHEOPS mission with the University of Geneva. In addition, Bernese researchers are among the world leaders when it comes to models and simulations of the formation and development of planets.
With the discovery of the first exoplanet, the University of Geneva positioned itself as one of the leading institutions in the field. This led, for example, to the construction and installation of the HARPS spectrograph on ESO's 3.6 m telescope at La Silla in 2003 under Geneva's leadership. This was followed by the ESPRESSO instrument on ESO's VLT telescope in Paranal. The "Science Operation Center" of the CHEOPS mission is also in Geneva.
ETH Zurich and the University of Zurich are also partner institutions in the NCCR PlanetS. Scientists from the fields of Astrophysics, Data Processing and Earth Sciences lead projects and make important contributions to NCCR PlanetS research. In addition, ETH is a world leader in instrumentation for various observatories and space missions.
The NCCR PlanetS is organized into the following research areas:
-Early stages of planet formation
-Architecture of planetary systems, their formation and evolution
-Atmospheres, surfaces and the interior of planets
Bernese space exploration: With the world's elite since the first moon landing
When the second man, "Buzz" Aldrin, stepped out of the lunar module on July 21, 1969, the first task he did was to set up the Bernese Solar Wind Composition experiment (SWC) also known as the "solar wind sail" by planting it in the ground of the moon, even before the American flag. This experiment, which was planned and the results analyzed by Prof. Dr. Johannes Geiss and his team from the Physics Institute of the University of Bern, was the first great highlight in the history of Bernese space exploration.
Ever since Bernese space exploration has been among the world's elite. The University of Bern has been participating in space missions of the major space organizations, such as ESA, NASA, ROSCOSMOS and JAXA. It is currently co-leading the European Space Agency's (ESA) CHEOPS mission with the University of Geneva. In addition, Bernese researchers are among the world leaders when it comes to models and simulations of the formation and development of planets.
The successful work of the Department of Space Research and Planetary Sciences (WP) from the Physics Institute of the University of Bern was consolidated by the foundation of a university competence center, the Center for Space and Habitability (CSH). The Swiss National Fund also awarded the University of Bern the National Center of Competence in Research (NCCR) PlanetS, which it manages together with the University of Geneva.
The end of Darwin's nightmare at Lake Victoria?
According to a study conducted by researchers from the University of Liège (Belgium), the lake is not only suffering from the introduction of the Nile perch into its waters
Lake Victoria, which came under the spotlight in 2004 by the documentary "Darwin's nightmare", is not only suffering from the introduction and commercialisation of the Nile perch. A study lead researchers from the University of Liège (Belgium) has highlighted other worrying phenomena, particularly climatic ones, which have an equally important impact on the quality of the lake's waters.
Located in East Africa, just south of the Equator, Lake Victoria is the source of the Nile and is the largest tropical lake in the world. With a surface area of 68,800 km² (twice the size of Belgium), it is considered to be one of the largest water and fishery resources in East Africa, supporting more than 47 million people in the three neighbor countries (Uganda, Tanzania and Kenya).
Lake Victoria is best known to the general public following the release of the 2004 documentary Darwin's Nightmare, which focuses on the environmental and social effects of the Nile perch fishing industry. Voracious predator that can grow up to two metres long and weigh 200kg, the Nile perch is the largest freshwater fish. Its introduction into Lake Victoria in the 1950s and its population explosion in the 1960s gradually wiped out the native fish species living in the lake, causing a major ecological disaster. Today, the Nile perch population remains ubiquitous but has declined slightly due to overfishing, allowing some species to partially recover.
What is less well known - and perhaps interacting with the presence of the Nile perch - but equally damaging to the ecosystem, is the general water quality of the lake. "This declined sharply between the 1960s and the 1990s due to eutrophication, which is caused by increased inputs of nutrients (nitrogen and phosphorus) into the water bodies (rivers and lakes) as a result of increased human activities in the catchment area (intensive agriculture with fertilisers or domestic wastewater) resulting from population growth and economic development, explains Alberto Borges, FNRS Research Director at the Laboratory of Chemical Oceanography from the University of Liege. »
This eutrophication leads to a significant development of micro-algae (phytoplankton). In particular, cyanobacteria, blue-green micro-algae, can be problematic for human health as some forms are toxic. Moreover, the excess phytoplankton biomass (the organic matter from these algae) cannot generally be transformed by the rest of the food web," continues the researcher. This excess remains unused and stagnant at the bottom of the lakes, creating a phenomenon of anoxia, the absence of oxygen in the bottom waters of the lakes. This leads to the degradation of the ecosystem. »
Since the 1990s, no large-scale study of the water quality of Lake Victoria had been undertaken. It was within the framework of the LAVIGAS project - funded by the FNRS and led by Alberto Borges - that a research team was able to study the biomass and composition of phytoplankton as well as the nutrient status of the lake during three scientific missions (2018 -2019). This study shows that the phytoplankton biomass has decreased by about seven times compared to the 1990s," says the researcher, "and that the species composition has also changed in a subtle way." What seems to be good news for the environment of Lake Victoria may only be so on the surface...
Paradoxically, the quantity of nutrients remained comparable to that of the 1990s. This paradox can be explained, however, because in addition to nutrients, phytoplankton (like all plants) also need light to grow. In lakes, the amount of light for phytoplankton obviously depends on the solar radiation at the surface of the lake, but also on the depth of the water on which the phytoplankton cells reside. This depth, known as the mixing layer, depends mainly on the intensity of the wind. If the wind is intense, the depth of the mixing layer is greater, and the phytoplankton cells spend less time near the surface where the light is more intense, and do not develop as well," explains Alberto Borges. Our work shows that current weather conditions are windier than in the 1990s, so the depth of the mixed layer is greater and phytoplankton growth less intense than in the 1990s." The weaker winds of the 1990s were related to the prevailing conditions of El Niño, a natural oscillation in global climate that originates from the large-scale atmospheric circulation over the Pacific Ocean and affects climate worldwide.
This rather complex story shows that the established climate regime in the Pacific Ocean (El Niño) affects the ecology of a lake in Africa, on the other side of the planet! More specifically, it shows that the growth of phytoplankton - and therefore the rest of the food chain - in large tropical lakes responds to eutrophication in a complex way and is strongly modulated by climate," says Alberto Borges. "This means that the current improvement in water quality in Lake Victoria may only be temporary, and that conditions could deteriorate again in the future if vertical mixing in the lake decreases due to reduced wind intensity (a new period of prevailing El Niño conditions) or due to continued climate warming.
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Study: Men doing more family caregiving could lower their risk of suicide
Men overinvest in economic-provider work, and underinvest in family care work
Colorado State University Professor of Psychology Silvia Sara Canetto has spent many years researching patterns and meanings of suicide by culture, trying to make sense of the variability in women's and men's suicide mortality around the world. Suicide rates are generally higher in men than in women, but not everywhere - which suggests cultural influences.
Canetto and colleagues have completed a new study that provides insight into what may contribute to men's suicide vulnerability. The study tests Canetto's theory that men's suicide mortality is related to men's private-life behaviors, specifically their low engagement in family care work - not just the adversities they may encounter in aspects of their public lives, such as employment.
Theories of male suicide
Many theories have been proposed to explain male suicide, Canetto said. Most link men's suicide mortality to the stresses and the demands of their employment and their economic-provider roles. These theories typically predict that male suicide rates would be higher when their employment and economic-provider roles are under threat.
Within this perspective, the typical suicide-prevention recommendation is to strengthen men's employment/economic provider role, for example, via programs that protect or support finding employment. Studies show, however, that economic adversities, including male unemployment, do not fully explain men's suicide vulnerability.
According to Canetto, men overinvest in economic-provider work, and underinvest in family care work--a pattern that leaves them vulnerable when economic-provider work is threatened or lost.
Men's family caregiving, unemployment, and suicide
The multinational and multidisciplinary study, published in Social Psychiatry and Psychiatric Epidemiology by Canetto, Ying-Yeh Chen, ZiYi Cai, Qingsong Chang, and Paul Yip, offers evidence of a suicide-protective role for men who engage in family caregiving. In their study, family caregiving was defined as, for example, providing personal care or education for a child, and/or providing care for a dependent adult.
The researchers examined suicide, male family caregiving, and unemployment in 20 countries, including the United States, Austria, Belgium, Canada and Japan. Suicide rates were found to be lower in countries where men reported more family care work.
In countries where men reported more such care work, higher unemployment rates were not associated with higher suicide rates in men. By contrast, in countries where men reported less family care work, higher unemployment rates were associated with elevated male suicide rates. Incidentally, unemployment benefits did not reduce male suicide rates.
Taken together, the findings of this ecological study suggest that men's family care work may protect them against suicide, particularly under difficult economic circumstances, Canetto said.
"Our study took a public health perspective. It examined population-level social and economic factors that may be driving population suicide patterns, across a range of countries," Canetto said. "Its findings point to new directions for suicide prevention."
"It appears that men benefit from doing family care work in terms of suicide protection. Doing family care work would be a way for men to diversify their sources of meaning and purpose, as well as their social capital and networks" stated Canetto. Men's greater involvement in family care work would also relieve women of their disproportionate caregiving load, and give children more resources.
The study's findings suggest incorporating support for engagement in family care work in programs aimed at reducing men's suicide mortality. "This means expanding beyond dominant frameworks of men's suicide prevention with their employment-support focus," Canetto explained. "It also means going beyond treating suicide as just a mental health problem to be solved with mental health 'treatments.'"
Finally, Canetto pointed out that the study's findings are consistent with other research findings. Collectively, they suggest that "having both family care work and family economic responsibilities is more conducive to well-being, health and longevity for men and women than a gendered division of family labor."
IMAGE: CLOSTRIDIOIDES DIFFICILE (C. DIFFICILE) IS CLASSIFIED AS AN URGENT ANTIBIOTIC RESISTANCE THREAT BY THE CDC. THE 3-D STRUCTURE SHOWS HOW A KEY C. DIFFICILE TOXIN, TCDB (GREY SURFACE MODEL), ENGAGES... view more
CREDIT: UCI SCHOOL OF MEDICINE
Irvine, CA - June 18, 2021 - A new study paves the way for the development of next generation therapeutics for the prevention and treatment of Clostridioides difficile infection (CDI), the most frequent cause of healthcare-acquired gastrointestinal infections and death in developed countries.
Published today in Nature Communications, the study reveals the first 3D structure of the Clostridioides difficile toxin B (TcdB) in complex with chondroitin sulfate proteoglycan 4 (CSPG4), a human receptor. The study was co-led by senior author Rongsheng Jin, PhD, a professor in the Department of Physiology & Biophysics at the University of California, Irvine, School of Medicine, and Min Dong, PhD, an associate professor at Harvard Medical School.
"TcdB is one of two homologous C. difficile exotoxins, which are major virulence factors responsible for the spread of C. difficile infections," explained Jin. "TcdB alone is capable of causing the full-spectrum of diseases associated with CDI in humans."
Previous studies had identified CSPG4 as a potential receptor for TcdB, however the pathophysiological relevance and molecular details were unknown. Results from this new study reveal a unique binding site involving TcdB and CSPG4, and also show that CSPG4-binding residues are highly conserved across most TcdB variants known to date.
CDI has become the most common cause of antibiotic-associated diarrhea and gastroenteritis-associated death in developed countries, accounting for approximately 223,900 infections, 12,800 deaths, and $1 billion in healthcare costs in the United States in 2017. It is classified as one of the top five "urgent threats" by CDC. There is also growing global concern surrounding the emergence of rapidly spreading hypervirulent C. difficile strains, reminiscent of the current COVID pandemic.
"What these new findings tell us is that a rationally designed CSPG4-mimicking decoy could neutralize major TcdB variants, providing a unique therapeutic avenue for combating some of the hypervirulent C. difficile strains," said Jin. In contrast, researchers also revealed that the therapeutic mechanism for bezlotoxumab, the only FDA approved anti-TcdB antibody, is sensitive to escaping mutations in some bacterial strains.
The current standard of care for CDI involves treatments using broad spectrum antibiotics, which often lead to frequent disease recurrence. While bezlotoxumab could reduce the recurrence rate of CDI in some patients, results from this and some earlier studies indicate it has weaker potency against some TcdB variants.
"We have designed a CSPG4-mimicking decoy based on the 3D structure we observed, which could neutralize major TcdB variants and is superior to bezlotoxumab on a major TcdB variant from a hypervirulent strain (TcdB2) in our studies. As a highly conserved cellular receptor of TcdB, a CSPG4 decoy molecule would be difficult for TcdB to escape, since any mutations that disrupt toxin binding to the decoy would also disrupt binding to its native receptors," said Jin.
The team of researchers has also developed a family of recombinant protein therapeutics based on these new findings, as well as on an earlier discovery on how TcdB recognizes another human receptor Frizzled (FZD).
"We are now examining the therapeutic features of these novel antitoxin molecules, and we believe they could provide broad-spectrum protection and neutralization against most known TcdB variants, thus improving existing antibody therapeutics for CDI," said Jin, whose team has filed a patent on these neutralizing molecules.
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This work was supported by part by the National Institutes of Health, Niedersächsisches Vorab, Deutsche Forschungsgemeinschaft, and the Burroughs Wellcome Fund.
About the UCI School of Medicine
Each year, the UCI School of Medicine educates more than 400 medical students, and nearly 150 doctoral and master's students. More than 700 residents and fellows are trained at UCI Medical Center and affiliated institutions. The School of Medicine offers an MD; a dual MD/PhD medical scientist training program; and PhDs and master's degrees in anatomy and neurobiology, biomedical sciences, genetic counseling, epidemiology, environmental health sciences, pathology, pharmacology, physiology and biophysics, and translational sciences. Medical students also may pursue an MD/MBA, an MD/master's in public health, or an MD/master's degree through one of three mission-based programs: the Health Education to Advance Leaders in Integrative Medicine (HEAL-IM), the Leadership Education to Advance Diversity-African, Black and Caribbean (LEAD-ABC), and the Program in Medical Education for the Latino Community (PRIME-LC). The UCI School of Medicine is accredited by the Liaison Committee on Medical Accreditation and ranks among the top 50 nationwide for research. For more information, visit som.uci.edu.
