Tech

Scientists have shed new light on a relationship between a sea slug and tiny structures called chloroplasts from their food algae that allow the animals to photosynthesise in a similar way to plants.

The findings, originally posted on bioRxiv* and published today in eLife, add to our understanding of this animal-chloroplast relationship and photosynthetic animals more widely.

The sea slug Elysia timida (E. timida) is typically found living in shallow Mediterranean waters. Similarly to plants, these organisms are able to photosynthesise, meaning they can use sunlight to produce sugar from carbon dioxide and water. The process is enabled by chloroplasts from the alga Acetabularia acetabulum that the sea slugs feed on.

"These stolen chloroplasts are located in the slugs' digestive tract cells and remain functional for a long time, but little is known about this peculiar animal-chloroplast relationship," explains lead author Vesa Havurinne, Doctoral Student in Molecular Plant Biology at the University of Turku, Finland. "One question concerns the dual nature of light. Light is necessary to drive photosynthesis, but at the same time causes continuous damage to the chloroplasts. How do the slugs protect the chloroplasts from this damage?"

To answer this question, Havurinne and senior author Esa Tyystjärvi, Teacher in Molecular Plant Biology at the University of Turku, used methods such as chlorophyll fluorescence to compare the process of photosynthesis in a large continuous culture of E. timida sea slugs and their prey alga Acetabularia acetabulum grown in the lab. Their results showed that living inside the slugs changes the interior of the chloroplasts in a way that reduces damage to them caused by light.

The team identified three protection mechanisms. First, when exposed to light, slug chloroplasts switch on a mechanism that efficiently converts light energy to heat. Next, the chloroplasts maintain a photosynthetic electron transfer chain in a neutral, oxidised state. This chain then allows the chloroplasts to perform photosynthesis within the slugs, while relying on safe energy 'sinks' such as flavodiiron proteins to accept excess electrons.

"Our results suggest that these photoprotective mechanisms contribute to the long-term functionality of chloroplasts inside the sea slugs, shedding light on this fascinating biological phenomenon," Tyystjärvi says. "This work may also help us better understand occurrences of similar relationships between organisms from earlier in evolution."

He adds that chloroplasts stolen from food algae may impact the longevity of sea slugs. The team's next steps will involve looking at how the intrinsic properties of the chloroplasts affect their lifespan inside E. timida and other slug species.

Intranasal administration of an anti-inflammatory drug helped reduce disease progression in a preclinical model of multiple sclerosis, according to recent research out of the University of Alberta.

Christopher Power, professor in the Faculty of Medicine & Dentistry, and Leina Saito, a graduate student on his team, showed that delivering an anti-inflammatory drug to mice helped prevent damage to brain cells, effectively slowing the progression of the disease.

MS is a devastating illness with no known cause and no cure. Power's lab seeks to better understand the disease to develop effective treatments.

"Nerves in the brain are like insulated wires, but in MS there is initially a loss of the insulation [called myelin], and then the eventual loss of the wire. Those losses are caused by inflammation. That inflammation, which we think is the driving force for MS, is our main research interest," said Power, a neurologist in the Northern Alberta MS Clinic, co-director of the U of A's MS Centre and member of the Neuroscience and Mental Health Institute.

His research group is particularly interested in inflammasomes, molecules that are responsible for the activation of an inflammatory response in the body. For a disease such as MS, that response must be controlled to halt the progression. Power's lab identified a drug called VX-765 as a strong candidate therapy for MS patients.

The drug works by inhibiting caspase-1, a component of inflammasomes that promotes harmful inflammation in the body. In previous research, Power's group saw beneficial results by delivering insulin intranasally in other models of brain inflammation, and he decided to go with that delivery route again. Using mouse models, Power dissolved VX-765 in a fluid and then injected the mixture into the nose.

"It's a lot easier for patients because you need less of the drug. It's a direct delivery into the brain, it doesn't go into the circulatory system and it's not broken down as quickly," said Power of the intranasal delivery method.

To examine the impact of VX-765 on the nerves, Power collaborated with researcher Frank Wuest, interim chair in the U of A's Department of Oncology and member of the Cancer Research Institute of Northern Alberta. Wuest is a world expert on positron emission tomography (PET) scanning, an imaging technique that uses radioactive substances to visualize changes in the body. Wuest used PET scans to look at brain metabolism and was able to document whether the insulation had been stripped or not after the therapeutic was delivered.

"The study shows intranasal therapy is effective in preventing demyelination and axon injury and loss, so that's a real tonic for us to keep going," said Power. "The loss of myelin and loss of nerves are irreversible processes, so any therapeutic that helps to slow or prevent that from happening is an exciting advance for MS research. The particular delivery method also allows the therapy to be delivered in a more precise and targeted way."

New York, NY (October 20, 2020) -- Researchers at Mount Sinai have proposed a groundbreaking new way to study the interaction between complex biological systems in the body and the environment. Their theory suggests the existence of "biodynamic interfaces," an intermediate entity between the two realms, as opposed to conventional approaches that analyze individual aspects of the interaction between the environment and humans in isolation, according to a paper published in BioEssays in October.

Video:https://www.youtube.com/watch?v=81HlHx1qf2g&feature=youtu.be

The environment impacts human health in profound ways, yet few theories define the form of the relationship between human physiology and the environment. The Mount Sinai scientists believe that such complex systems cannot interact directly, but rather that their interaction requires the formation of an intermediary "interface." The scientists believe that this theory will lead to the establishment of a new field, "environmental biodynamics," that will advance the way the environment and human health are studied.

The basis of their theory arose when they compared the time period when autistic children were exposed to toxins to how the children's brains functioned afterward. At the same time, they found distinct patterns in the intake and metabolism of essential elements and toxins, which were dependent not only on the timing and magnitude of the environmental exposure but also on what was happening within the biological systems of the child's body.

"These rhythms were driven by the properties of both the biological and environmental systems, but exhibited properties independent of either system," said Manish Arora, PhD, the Edith J. Baerwald Professor and Vice Chair of Environmental Medicine and Public Health at the Icahn School of Medicine at Mount Sinai. "They supported the existence of an interface mediating the interaction of biological and environmental systems. The interface itself, which applies constraints and passes information between interacting systems, must be the subject of inquiry because without refocusing the attention on biodynamic interfaces, how the environment impacts health cannot be discerned."

The study of the interface will allow scientists to better understand how complex systems like the environment and human physiology affect each other. Current methods using plain analysis are incomplete, the scientists say.

"The standard course of inquiry measures some aspect of the environment like lead in the water, and we'd link this to some aspect in human development like IQ," said Paul Curtin, PhD, Assistant Professor of Environmental Medicine and Public Health at the Icahn School of Medicine at Mount Sinai, an author on the paper. "We've learned a lot from environmental health using this approach, but it has its limits."

This interface also considers social, behavioral, and cultural dynamics to be a particularly fruitful avenue of research. This new theory would allow scientists to assess the interface between income and other processes, including health outcomes using dynamical systems methods. It would also define how human activities could negatively influence the environment and negatively influence their own health outcomes and further environmental impacts over time.

Dr. Arora's work was funded by a prestigious Revolutionizing Innovative, Visionary Environmental Health (RIVER) Award from the National Institute of Environmental Health Sciences, totaling $8 million over eight years to complete research on the biodynamic interface. Alessandro Giuliani, PhD, Professor of Environmental Health at the University of Rome, has made a significant contribute to the development of the theory.

"Arora, Giuliani, and Curtin's conjecture is potentially a major breakthrough, as knowing the factors that influence biological time may be the key to understanding why people age or mature at different rates, and how our early life experiences can influence our health as adults," said Robert O. Wright, MD, MPH, Ethel H. Wise Professor and Chair of Environmental Medicine and Public Health and Director of the Institute for Exposomic Research at the Icahn School of Medicine at Mount Sinai.

As the world grapples with the coronavirus (COVID-19) pandemic, another virus has been raging again in the Democratic Republic of the Congo in recent months: Ebola. Since the first terrifying outbreak in 2013, the Ebola virus has periodically emerged in Africa, causing horrific bleeding in its victims and, in many cases, death.

How can we battle these infectious agents that reproduce by hijacking cells and reprogramming them into virus-replicating machines? Science at the molecular level is critical to gaining the upper hand -- research you'll find underway in the laboratory of Professor Juan Perilla at the University of Delaware.

Perilla and his team of graduate and undergraduate students in UD's Department of Chemistry and Biochemistry are using supercomputers to simulate the inner workings of Ebola, observing the way molecules move, atom by atom, to carry out their functions. In the team's latest work, they reveal structural features of the virus's coiled protein shell, or nucleocapsid, that may be promising therapeutic targets, more easily destabilized and knocked out by an antiviral treatment.

The research is highlighted in the Tuesday, Oct. 20 issue of the Journal of Chemical Physics, which is published by the American Institute of Physics, a federation of societies in the physical sciences representing more than 120,000 members.

"The Ebola nucleocapsid looks like a Slinky walking spring, whose neighboring rings are connected," Perilla said. "We tried to find what factors control the stability of this spring in our computer simulations."

The life cycle of Ebola is highly dependent on this coiled nucleocapsid, which surrounds the virus's genetic material consisting of a single strand of ribonucleic acid (ssRNA). Nucleoproteins protect this RNA from being recognized by cellular defense mechanisms. Through interactions with different viral proteins, such as VP24 and VP30, these nucleoproteins form a minimal functional unit -- a copy machine -- for viral transcription and replication.

While nucleoproteins are important to the nucleocapsid's stability, the team's most surprising finding, Perilla said, is that in the absence of single-stranded RNA, the nucleocapsid quickly becomes disordered. But RNA alone is not sufficient to stabilize it. The team also observed charged ions binding to the nucleocapsid, which may reveal where other important cellular factors bind and stabilize the structure during the virus's life cycle.

Perilla compared the team's work to a search for molecular "knobs" that control the nucleocapsid's stability like volume control knobs that can be turned up to hinder virus replication.

The UD team built two molecular dynamics systems of the Ebola nucleocapsid for their study. One included single-stranded RNA; the other contained only the nucleoprotein. The systems were then simulated using the Texas Advanced Computing Center's Frontera supercomputer - the largest academic supercomputer in the world. The simulations took about two months to complete.

Graduate research assistant Chaoyi Xu ran the molecular simulations, while the entire team was involved in developing the analytical framework and conducting the analysis. Writing the manuscript was a learning experience for Xu and undergraduate research assistant Tanya Nesterova, who had not been directly involved in this work before. She also received training as a next-generation computational scientist with support from UD's Undergraduate Research Scholars program and NSF's XSEDE-EMPOWER program. The latter has allowed her to perform the highest-level research using the nation's top supercomputers. Postdoctoral researcher Nidhi Katyal's expertise also was essential to bringing the project to completion, Perilla said.

While a vaccine exists for Ebola, it must be kept extremely cold, which is difficult in remote African regions where outbreaks have occurred. Will the team's work help advance new treatments?

"As basic scientists we are excited to understand the fundamental principles of Ebola," Perilla said. "The nucleocapsid is the most abundant protein in the virus and it's highly immunogenic -- able to produce an immune response. Thus, our new findings may facilitate the development of new antiviral treatments."

Currently, Perilla and Jodi Hadden-Perilla are using supercomputer simulations to study the novel coronavirus that causes COVID-19. Although the structures of the nucleocapsid in Ebola and COVID-19 share some similarities -- both are rod-like helical protofilaments and both are involved in the replication, transcription and packing of viral genomes -- that is where the similarities end.

"We now are refining the methodology we used for Ebola to examine SARS-CoV-2," Perilla said.

TAMPA, Fla (Oct. 20, 2020) -- Our immune system's capacity to mount a well-regulated defense against foreign substances, including toxins, weakens with age and makes vaccines less effective in people over age 65. At the same time, research has shown that immunotherapy targeting neurotoxic forms of the peptide amyloid beta (oligomeric Aβ) may halt the progression of Alzheimer's disease, the most common age-related neurodegenerative disease.

A team led by Chuanhai Cao, PhD, of the University of South Florida Health (USF Health), has focused on overcoming, in those with impaired immunity, excess inflammation and other complications that interfere with development of a therapeutic Alzheimer's vaccine.

Now, a preclinical study by Dr. Cao and colleagues indicates that an antigen-presenting dendritic vaccine with a specific antibody response to oligomeric Aβ may be safer and offer clinical benefit in treating Alzheimer's disease. The vaccine, called E22W42 DC, uses immune cells known as dendritic cells (DC) loaded with a modified Aβ peptide as the antigen.

The Alzheimer’s mouse model study of this new investigational vaccine was published early online Oct. 13 in the Journal of Alzheimer’s Disease.

One of the two hallmark pathologies of Alzheimer's disease is hardened deposits of Aβ that clump together between nerve cells (amyloid protein plaques) in the brain; the other is neurofibrillary tangles of tau protein inside brain cells. Both lead to damaged neurological cell signaling, ultimately causing the onset of Alzheimer's disease and symptoms.

"This therapeutic vaccine uses the body's own immune cells to target the toxic Aβ molecules that accumulate harmfully in the brain," said principal investigator Dr. Cao, a neuroscientist at the USF Health Taneja College of Pharmacy, USF Health Morsani College of Medicine and the university's Byrd Alzheimer's Center. "And, importantly, it provides strong immunomodulatory effects without inducing an unwanted, vaccine-associated autoimmune reaction in the aging mice."

Unfortunately, clinical trials of all anti-amyloid treatments for Alzheimer's disease so far have failed - including the initial vaccine trial targeting Aβ (AN-1792), which was suspended in 2002 after several immunized patients developed central nervous system inflammation. "Inflammation is a primary symptom of Alzheimer's disease, so any possible treatment with neural inflammation as a side effect essentially pours gas on the fire," Dr. Cao said.

A next-generation anti-amyloid vaccine for Alzheimer's would ideally produce long-lasting, moderate antibody levels needed to prevent Aβ oligomers from further aggregating into destructive Alzheimer's plaques, without over-stimulating the immune systems of elderly people, Dr. Cao added.

In this study, the researchers tested the vaccine they formulated using modified Aβ-sensitized dendritic cells derived from mouse bone marrow. Dendritic cells interact with other immune cells (T-cells and B-cells) to help regulate immunity, including suppressing harmful responses against healthy tissues.

"Because we use dendritic cells to generate antibodies, this vaccine can coordinate both innate and acquired immunity to potentially overcome age-related impairments of the immune system," Dr. Cao said.

The study included three groups of transgenic (APP/PS1) mice genetically engineered to develop high levels of Aβ and behavioral/cognitive abnormalities that mimic human Alzheimer's disease. One group was vaccinated with the investigational E22W42 DC vaccine, another received an endogenous amyloid beta peptide to stimulate dendritic cells (wild-type vaccine group), and the third was injected with dendritic cells only, containing no Aβ peptide (DC control group). A fourth group was comprised of untreated healthy, older mice (nontransgenic control group).

Among the study findings:

The vaccine slowed memory impairment in the Alzheimer's transgenic mice, with mice in the E22W42 DC-vaccinated group demonstrating memory performance similar to that of the nontransgenic, untreated mice. In a cognitive test called a radial arm water maze, the E22W42 DC-vaccinated mice also showed significantly less errors in working memory than the mice injected with non-sensitized dendritic cells only (DC controls). Loss of working memory makes it difficult to learn and retain new information, a characteristic of Alzheimer's disease.

No significant differences were found in the quantities of inflammatory cytokines measured in the plasma of the vaccinated mice, versus amounts in the control mice. The researchers concluded that the E22W42 DC vaccine has "little potential for over priming the immune system."

E22W42 DC-vaccinated mice showed higher levels of anti-Aβ antibodies in both in their brains and in their blood than the transgenic control mice administered dendritic cells containing no modified Aβ peptide.

Only Aβ peptides with mutations introduced in the T-cell epitope (the distinct surface region of the antigen where complementary antibodies bind) can sensitize the dendritic cells to target toxic oligomeric forms of Aβ, the researchers reported. A major advantage of E22W42 is that the antigen can stimulate a specific T-cell response that activates the immune system and silence some T-cell epitopes associated with an autoimmune response, they added.

"Though the E22W42-sensitized DC vaccine is being developed for patients with Alzheimer's disease, it can potentially help strengthen the immune system of elderly patients (with other age-related disorders) as well," the study authors concluded.

Dr. Cao conducted the study with collaborators from Tianjin University of Traditional Chinese Medicine and Michigan State University. The team's research was supported by grants from the National Institutes of Health, Florida High Tech Corridor matching funds, and MegaNano Biotech Inc. The University of South Florida holds a patent related to E22W42 DC vaccine technology.

Changing the surface chemistry of electrodes leads to the preferential growth of a novel electroactive bacterium that could support improved energy-neutral wastewater treatment.

To grow, electroactive bacteria break down organic compounds by transferring electrons to solid-state substrates outside their cells. Scientists have utilized this process to drive devices, such as microbial electrochemical systems, where the bacteria grow as a film on an electrode, breaking down the organic compounds in wastewater and transferring the resultant electrons to the electrode.

Scientists are now looking for ways to improve this process so it produces hydrogen gas at a negatively charged cathode electrode, which can then be converted to electricity to power wastewater treatment plants. This needs electroactive bacteria that efficiently transfer electrons to a positively charged anode electrode that do not use hydrogen for their growth.

Krishna Katuri, a research scientist in the lab of Pascal Saikaly, and colleagues have now found a novel electroactive bacterium, called Desulfuromonas acetexigens, that preferentially grows when the surface chemistry of the anode is changed in a specific way. The bacterium produces a higher current density than the most important current-producing bacterium, Geobacter sulfurreducens, and in a shorter time.

"We consider this a breakthrough discovery in the field," says Katuri.

In tweaking the surface chemistry, the researchers modified graphite electrodes to produce amino, carboxyl and hydroxide groups on their surface. When sludge and acetate, an organic compound used as feed, were placed in a glass chamber together with the electrode, bacteria quickly grew on the electrode's surface. Analyses revealed that D. acetexigens preferentially grew quickly on the modified electrodes, while G. sulfurreducens grew on conventionally used unmodified electrodes tested as controls.

Further analyses showed that D. acetexigens generated a current density of around 9 amperes per square meter within 20 hours of the process starting, compared with only 5 amperes per square meter in 72 hours by G. sulfurreducens.

Also, D. acetexigens does not use hydrogen as feed. This means that a microbial electrochemical reactor treating wastewater could combine the electrons and protons produced by this bacterium to generate hydrogen gas at the cathode.

"We next plan to study how D. acetexigens transfer electrons and to learn how to maximize their activity at the anode," says Saikaly. "We're also fabricating a pilot-scale microbial electrolysis cell reactor to treat domestic wastewater with this bacterium while recovering hydrogen gas as energy. Solar panels will be integrated into the pilot reactor with the aim of using solar and hydrogen energy to achieve energy-neutral or even possibly energy-positive wastewater treatment."

Spotting, pursuing and catching prey - for many animals this is an essential task for survival. Scientists at the Max Planck Institute of Neurobiology now show in zebrafish that the localization of neurons in the midbrain is adapted to a successful hunting sequence.

Far away, in the periphery of its visual field, a tiny zebrafish larva detects a small dot moving sideways. Is it prey or is it a threat, for instance, a distant predator sneaking up on it? Within the shortest possible time, the fish decides that it must be potential prey. The larva turns toward the object, approaches it, until it is right in front, and snaps shut - one of its daily hunting routines is successfully finished.

What might sound straightforward, is actually a highly complex process. Many different visual stimuli are detected simultaneously, transferred from the eye to the brain, and further processed. Interestingly, the stimuli don't reach the brain at random locations: every position on the retina is transmitted to a very specific location in the tectum of the midbrain, the processing hub for visual stimuli. However, apart from that, there is not much knowledge of how the neurons are wired and organized, or which signals they specifically react to.

Dominique Förster and a team from Herwig Baier's laboratory analyzed how retinal ganglion cells transfer visual information from the eye to the tectum and how this input is further processed. To do so, zebrafish larvae were presented in a virtual reality area with different visual stimuli, ranging from small and big prey-like objects to approaching threats similar to predatory fish. Using a special microscopy technique, the researchers not only analyzed the activity of hundreds of neurons in parallel, but also the location of their cellular projections.

Response to optical stimuli

Analyzing this pool of data showed that retinal ganglion cells as well as neurons in the tectum respond to optical stimuli in a highly specialized manner: While some cells are activated by small objects, others react to bigger objects, or even threats. Some cells are interested in the direction of motion, others only in whether the environment gets darker or brighter. Interestingly, the special-purpose neurons do not distribute randomly in the tectum. Retinal ganglion cells reacting to threats send their projections into deep tectal layers, where they meet the receiving processes, or dendrites, of tectal neurons. In contrast, cells responding to prey-like objects make synaptic connections in more superficial layers. This specialization of different tectal layers most likely allows zebrafish to quickly distinguish between prey and threat - an essential skill for survival.

The researchers then discovered that the prey-specific cells of the upper layers are arranged in a way that is advantageous for the hunting sequence: prey usually appears first at a distance in the peripheral visual field. Such images are represented in the back part of the tectum. Strikingly, this region of the tectum is enriched with cells reacting to small moving objects. When the fish turns toward the prey and approaches it, the prey's image moves to the front part of the tectum and gets bigger, until it appears directly in front of the fish. There it is held steady by the fish's own movement, until the prey can be captured by a vigorous strike. Neurons tuned to visual input with these characteristics, that is, large and steady, sit in the frontal region of the tectum - exactly where this kind of information reaches the brain.

This study shows that the arrangement and connectivity of neurons in the tectal brain map is adapted to the demands of hunting. Specialized cells localize to brain regions where their function is best suited for an efficient catch. By using the hunting behavior of zebrafish as an example, the researchers were able to demonstrate the impact of natural selection on the layout of relevant brain regions. These results remind us that the way animals (including us) perceive the world is shaped by evolution. The way the brain is wired has worked best to ensure survival in the past.

Month-on-month, year-on-year, the world continues to experience record high temperatures. In response to this and exacerbated by a growing global population, it is expected that air-conditioning demand will continue to rise. A new IIASA-led study explored the pros and cons of seawater air-conditioning as an alternative cooling solution.

Conventional air-conditioning (AC) is the most common technology used for cooling and represents a considerable share of energy demand in warmer regions. An alternative that is not frequently considered, is seawater air-conditioning (SWAC) - a renewable alternative for cooling that involves pumping seawater from ocean depths of around 700 to 1200 meters and temperatures of 3°C to 5°C to the coast, where it exchanges heat with a district cooling system, and returns the warmer water to the ocean.

According to the study published in the journal Energy Efficiency, just 1 m³ of seawater in a SWAC plant can provide the same cooling energy as that generated by 21 wind turbines or a solar power plant the size of 68 football fields. The researchers developed a computational model and methodology to estimate the cost of cooling with SWAC around the world, and also evaluated the possibility of using this system as an alternative for energy storage from variable renewable energy sources like wind and solar.

The results show that whereas conventional air-conditioning systems require a low initial investment cost but the energy costs to operate them are high, for SWAC systems the opposite is true - while it has a higher initial investment cost, energy costs to operate the system is low.

The main potential for SWAC is on small islands in tropical regions, where the distance from the coast to the deep ocean is small, energy costs are high, and warm average temperatures are common throughout the year. For example, in Puerto Plata where the electricity costs are $0.16/KWhe, the cost of conventional AC cooling is around $0.08/KWht. The SWAC solution would cost $ 0.042/KWht, which is 48% less than conventional technologies. In Nauru, assuming the same electricity cost, the SWAC solution would be $0.0185/KWht, which is 77% lower compared with conventional technologies.

While district cooling is usually less viable than district heating systems, the low cost of cooling with SWAC processes makes district cooling over short distances a viable alternative. Possible customers with high cooling demands to connect to SWAC district cooling systems include airports, data centers, hotels and resorts, governmental and military facilities, universities, and commercial buildings.

The findings further indicate that excess generation of electricity from variable renewable energy sources such as wind and solar energy can be balanced out with the variations in seawater flow in the pipeline of SWAC plants. This cold water would then be stored in thermal energy storage tanks to meet the cooling demand at any time. During months or seasons where cooling demand is low, the cold seawater can be used to increase the efficiency of a chiller to freeze sea or freshwater in the storage tanks. During the months when cooling demand is high, both the SWAC system and the energy stored as ice in the tanks can supply the cooling demand.

In addition to the above, the paper also suggests a modification to the normal design that can increase the efficiency of SWAC projects with long pipelines, while allowing for expansion to meet growing cooling demand. The proposal involves increasing the excavation depth of the seawater pump station, which allows an increase in the velocity and flow rate of the seawater inlet pipeline.

"We call this approach "High Velocity Seawater Air-conditioning". This design configuration allows such projects to be built with an initial cooling load and expand the cooling load modularly through smaller additional capital costs," explains study lead author Julian Hunt, who did this research during his postdoc at IIASA.

Other advantages of SWAC includes its reliability as a non-intermittent renewable source of cooling, reduction of greenhouse gas emissions from cooling processes, and the reduction of water consumption in cooling systems. In addition, it could serve as a cheap alternative for large-scale cooling in tropical countries where it could reduce the costs of food and grain storage, thus helping to lower the vulnerability of developing countries to climate change. Given the recent interest in hydrogen production and hydrogen-based economies, SWAC could even be combined with hydrogen liquefaction plants where it could help to reduce energy consumption in the process to liquefy hydrogen by up to 10%.

The researchers however caution that despite its potential and many advantages, this technology also has challenges. The return of the seawater should, for instance, be handled with extreme care to minimize its impact on coastal wildlife; retrofitting district cooling infrastructure and buildings could incur high capital costs; and there is a risk of thermal shock and increased nutrient loading in the deep seawater outlet.

"While it does have its challenges, seawater air-conditioning is an innovative and sustainable technology that has great potential for expanding into a benchmark system for cooling in tropical locations close to the deep sea and will help fulfill our cooling needs in a warming world," Hunt concludes.

Cochlear implants are a groundbreaking technology that has changed the lives of many people living with severe to profound hearing loss.

University of Sydney School of Biomedical Engineering researcher, Dr Greg Watkins, hears with the assistance of two cochlear implants after experiencing profound deafness in both ears following a 30-year career as an electrical engineer. Despite his profound deafness, with the help of his cochlear implant he has been able to complete a PhD in biomedical engineering.

Dr Watkins' desire to help others living with deafness, his personal experience and career in engineering, motivated him to research cochlear implants. Now, his new paper has analysed the accuracy of predictions for cochlear implant outcomes with a view to further improving their performance in environments with lots of background noise.

Published in Ear and Hearing the paper presents a new method for the prediction of speech perception for individual recipients, providing a methodology that could make patient trials more efficient, potentially leading to implants that are personalised to an individual's listening capability.

"My hearing deteriorated over a number of years and even with powerful hearing aids I had great difficulty having a conversation. Cochlear implants have helped to restore my hearing and stay connected socially and professionally," said Dr Watkins, who received his doctorate earlier this month.

"Cochlear implants often provide near-perfect speech perception in quiet conditions, but hearing can still be improved in noisy environments, like in cafés or near traffic, compared to having no hearing loss.

"Evaluation of new sound processing ideas and testing them on recipients is a lengthy process. We have developed a metric which reliably predicts cochlear implant speech intelligibility in a range of conditions, allowing for more sound processing ideas to be tested.

"We took existing hearing test results for cochlear implant recipients and, using the output signal to noise ratio (OSNR) metric, accurately predicted how well they would hear in a range of quite different listening conditions.

"Potentially, this metric could be used to develop configurations which are customised to an individual recipient's unique hearing capabilities," said Dr Watkins.

The study was conducted under the supervision of Head of School of Biomedical Engineering, Professor Gregg Suaning and Dr Brett Swanson, a researcher at Cochlear Ltd. Professor Suaning said the research could lead to better outcomes for implant recipients.

"Cochlear implants are already extraordinary devices and have transformed the lives of hundreds of thousands of people world-wide," said Professor Suaning.

"Despite their successes, there remain areas such as the cochlear implant's performance in noisy environments where a personalised approach in taking the sound from the environment and translating that into electrical stimulation could conceivably make a world of difference."

Dr Swanson said Dr Watkins' research could reduce the amount of time needed to test the viability of new cochlear implant algorithms.

"A cochlear implant stimulates the auditory nerve directly, so if you're a researcher with normal hearing, you can't listen to it yourself. Instead, we rely on dedicated volunteers with cochlear implants who spend hours in sound-proof rooms listening to sentences in noise and telling us what they hear. It is vital work, but mentally draining. This research has the potential to drastically reduce the amount of time that we need from our volunteers," said Dr Swanson.

HOW THE RESEARCH WORKED

The study was conducted as a retrospective analysis of existing clinical data sets. Each data set contained hearing test results of cochlear implant recipients in several test conditions.

The test condition closest to the recipient's "everyday" listening condition was taken as a reference and the scores in that condition mapped to a prediction metric, the Output Signal to Noise Ratio (OSNR).

The OSNR was then calculated in other listening conditions and combined with the reference speech scores to predict the intelligibility that would be achieved for an individual recipient. The predicted scores were compared to the clinical scores and had a high accuracy.

Dr Watkins is currently evaluating extensions of the OSNR metric to determine whether even more accurate predictions are feasible and hopes to work with a manufacturer to develop a more accurate sound processing system.

Concentration of dinitrogen oxide - also referred to as nitrous oxide - in the atmosphere increases strongly and speeds up climate change. In addition to CO2 and methane, it is the third important greenhouse gas emitted due to anthropogenic activities. Human-made nitrous oxide emissions are mainly caused by the use of fertilizers in agriculture. Growing demand for food and feed in future might further increase the emissions. This is one finding of an international study published in Nature, in which Karlsruhe Institute of Technology (KIT) was one of the partners. (DOI: 10.1038/s41586-020-2780-0)

Dinitrogen oxide (N2O), also called nitrous oxide, is about 300 times as climate-damaging as carbon dioxide. It stays for about 120 years in the atmosphere. Although it exists in the form of traces only, it has a very strong greenhouse effect and superproportionally contributes to anthropogenic climate change. Nitrous oxide concentration in the atmosphere today already is about 20% higher than the pre-industrial value. In past decades, increase has accelerated due to emissions from various anthropogenic activities. In total, worldwide N2O emissions in 2016 were about ten percent higher than those of the 1980s. An international study coordinated by researchers from Auburn University in Alabama/USA now presents the most comprehensive evaluation of all nitrous oxide sources and sinks so far. Under the title "A comprehensive quantification of global nitrous oxide sources and sinks," it is now reported in Nature. The conclusion: As a result of strongly increasing nitrous oxide emissions, the climate goals of the Paris Agreement are at stake.

"The increase in nitrous oxide concentration in the atmosphere is mainly caused by the use of nitrogen-containing fertilizers. These include both synthetic fertilizers and organic fertilizers from animal excretions," says ecosystems researcher Almut Arneth, Professor of the Atmospheric Environmental Research Division of KIT's Institute of Meteorology and Climate Research (IMK-IFU), KIT's Campus Alpine in Garmisch-Partenkirchen. She participated in the study. "From 2007 to 2016, agricultural production caused about 70% of anthropogenic global increase in N2O emissions since the 1980s." As global demand for food and feed is growing, researchers fear that also global N2O concentration will further increase and contribute to global warming.

N2O Emissions Decreased in Europe

According to the study, anthropogenic nitrous oxide emissions are highest in East and South Asia, Africa, and South America. Increases are particularly high in threshold countries, such China, India, and Brazil, where crop cultivation and animal husbandry have grown strongly. In Europe, by contrast, anthropogenic N2O emissions decreased, both in agriculture and chemical industry. Scientists explain this decrease by various incentives and protection measures. Agriculture in many West European countries has started to use nitrogen more efficiently in order to reduce water pollution, among others. "Our work provides an in-depth understanding of the N2O budget and its impacts on climate," Arneth explains. "It also shows that there are ways to reduce emissions, such as measures in agriculture that concern both production and consumption. Such measures do not only benefit the climate, but also biodiversity and human health."

57 scientists from 48 research institutions in 14 countries were involved in the study "A comprehensive quantification of global nitrous oxide sources and sinks" managed by Professor Hanqin Tian from Auburn University. The study was made within the framework of the Global Carbon Project and the International Nitrogen Initiative.

The Landau's theory of Fermi liquid (FL) (Note 1), established in the first half of the 20th century, is the foundation of the scientific and industrial usage of the metallic materials in our society. It is also the basis of our current understanding of metals. However, in the second half of the 20th century, more and more metallic materials were discovered which behave very differently. The non-Fermi liquid (NFL) behaviour of these "strange metals" remains a puzzle to physicists, and there is no established theory to explain them.

Recently, a joint research team comprising members including Dr Zi Yang MENG, Associate Professor of Department of Physics at the University of Hong Kong (HKU), Dr Avraham KLEIN and Professor Andrey CHUBUKOV from the University of Minnesota, Dr Kai SUN, Associate Professor from the University of Michigan, and Dr Xiao Yan XU from the University of California at San Diego, has solved the puzzle of the NFL behaviour in interacting electrons systems, and provided a protocol for the establishment of new paradigms in quantum metals, through quantum many-body computation and analytical calculations. The findings have recently been published in NPJ Quantum Materials. The work was supported by the Research Grants Council of HKSAR, and the Ministry of Science and Technology of China.

Breaking discoveries of mysterious NFL behaviour

The Landau's theory of Fermi liquid (FL) successfully explained many features of simple metals like Copper, Silver, Gold and Iron, such as when temperature changes, their resistivity, heat capacity and other properties follow simple function form with respect to temperature T (for example, resistivity follows ρ~T2 and heat capacity follows C~T, independent of material details). The success of the Fermi liquid theory lies in the central assumption that the electrons, the droplets in the Fermi liquid are not interacting with each other, but behave identically in the material.

However, many metallic materials which were discovered after FL was established, do NOT behave as FL. For example, in the so-called high-temperature superconductor compounds - copper oxides and iron pnictides - their resistivities are linear in temperature ρ~T before the system becomes superconducting (resistivity is then zero), and such systems are in general dubbed Non-Fermi-Liquids (NFL). Different from the simple FL, the electrons of NFL, the droplets, strongly interact with each other.

NFLs have potential application in solving the energy crisis

The physicists still do not have much clue about NFL, which makes it very difficult to make concrete predictions. Still, these systems are essential for the continued prosperity of human society, as NFLs hold the key in making use of high-temperature superconducting material that will solve the energy crisis. Currently, the so-called high-temperature superconducting materials still only work at temperature scale of-100 Celsius - they are called high-temperature in comparison with the FL superconductors, which work at temperature scale of -200 Celsius - so it is still hard to put high-temperature superconductors into daily usage at room temperature, but only then can we enjoy the nice properties of such material that the electronic power will not be loss in heat due to resistivity. Only when we understand how the NFL in high-temperature superconductor works at -100 Celsius, can we then design the ultimate material to work at room temperature. Therefore, the complete understanding of NFL is of vital importance.

Physicists from analytical background have been trying to understand NFL for about half a century. The problem of analytical calculation is that, due to the quantum many-body nature of the NFL, the convergence and accuracy of many theoretical predictions cannot be controlled or guaranteed; one would need unbiased quantum computation to verify these prepositions.

Key revelation to the puzzle is computation

At the numerical front, there have been many previous attempts, but the problem is that the results obtained are always different from the analytical prediction. For example, the most important quantity of the NFL, the self-energy Σ , which describes the level of the electron interactions in the material, is expected to have a power-law frequency dependence such as Σ~ω2/3in the model exhibited in Fig.1. However, the computed self-energy doesn't follow such as power-law, it shows a slow diverging behaviour, that is the self-energy computed doesn't go to zero as frequency is reduced, but instead gets larger and large, as the data in Fig.2 (b) indicated. Such difference makes the situation even more perplexing.

After a very inspirational discussion between Dr Meng, Professor Chubukov, and Dr Klein, they realized that the setting of the numerical simulation is actually different from that of the analytical calculation. Such subtlety comes from the fact that the model simulations are performed on the finite system at finite temperature, that is T?0, whereas the analytical expectations are strictly at the zero temperature T=0. In other words, the numerical data actually contain both the zero temperature NFL contribution and the contribution from the fluctuations at finite temperature. To be able to reveal the NFL behaviour from the lattice model simulation such as the setting in Fig.1, one would need to deduce the finite temperature contribution.

This turns out to be the key revelation to the puzzle of NFL. Dr Klein, Dr Sun and Prof Chubukov derived the analytical form of the finite temperature contribution (with the input from the lattice model in Fig.1 designed by Dr Meng and Dr Xu) for Dr Meng and Dr Xu to employ and deduce from the numerical data, the results are shown as the black dashed line and the data round it in Fig. 2(c). To everyone's surprise and ecstasy, the results after the deduction perfectly exhibit the expected NFL behaviour, from finite temperature all the way to zero temperature, the power-law is revealed. It is the first time that such clear NFL behaviour has been obtained from unbiased numerical simulation.

Bring a better future to the society

Dr Meng said it is expected that this work will inspire many follow-up theoretical and experimental researches, and in fact, promising results for further identification of NFL behaviour in another model system have been obtained by the further investigations, he said: "This research work reveals the puzzle of Non-Fermi-liquid for several decades and paves the avenue for the establishment of new paradigm of quantum metals beyond those more than half-a-century ago. Eventually, we will be able to understand the NFL materials such as high-temperature superconductors as we understand simple metals such as Cooper and Sliver now, and such new understanding will solve the energy crisis and bring better industrial and personal applications to the society."

Trees planted in urban spaces provide a multitude of ecosystem services: they reduce air pollution and noise, provide habitat and shelter for other species, and reduce erosion during heavy rains. They also offer opportunities for relaxation, attenuate urban heat islands and contribute both to landscapes and a sense of place. At the same time, trees can be a source of allergens, generate maintenance costs and cause accidents or threats to native biodiversity if introduced from elsewhere. This last point is the subject of an ongoing debate: do introduced species contribute to biodiversity and ecosystem services? Environmental scientists from the University of Geneva (UNIGE) - working in collaboration with the Botanical Gardens and Conservatory of the City of Geneva - have analysed a large data-base of trees found in the Geneva region, and systematically assessed the services and inconveniences they generate. The results of the study, to be published in Urban Forestry & Urban Greening, show that most tree species in Geneva are non-native, and that trees provide roughly the same ecosystem services to Geneva's urban spaces regardless of their origin.

Trees contribute to the quality of the environment and the well-being of humans. Evaluating these contributions is referred to as the "ecosystem services approach" by environmental specialists. Trees, it goes without saying, bring their share of disadvantages with them both for nature and human beings, chiefly the threat posed by introduced species to the native biodiversity. Martin Schlaepfer is a researcher in UNIGE's Institute of Environmental Sciences and first author of the study. "There's an ongoing philosophical debate concerning this problem at the moment," begins Dr Schlaepfer. "Should we promote native trees and ban - or at least put limits on - introduced species? Of all the species introduced into urban areas, only 5% are potentially problematic, such as the Tree of Heaven (Ailanthus altissima) located in the old town of Geneva. But what should we do with the remaining 95% of non-native tree species, and how should we value them?"

Foreign majority

In an attempt to answer these questions, the environmental specialists from UNIGE and the City of Geneva analysed the databases of tree species found in the urban and semi-urban region of the entire Canton of Geneva, i.e. all isolated or aligned trees excluding forests. The ecosystem services and drawbacks were analysed for each species, whether of native or non-native origin. Following four years of painstaking study, 911 different species were recorded, the vast majority of which - 90% - are non-native. This is an exceptional proportion for a city where the current botanical garden in the Nations district, together with the old gardens in the Parc des Bastions - with over 700 foreign species - contribute enormously to the diversity.

Non-native species adapted to urban environments

The analysis of ecosystem services showed that the trees are beneficial regardless of their origins. There are, of course, some exceptions: "Three invasive species were identified, and they are indeed potentially problematic when located in semi-natural sites outside the city. But in urban settings there is a low risk of propagation, and we document how they contribute to our well-being. Some non-native trees have been growing in the parks for several centuries, such as cedars and plane trees imported from North Africa and Asia in the 16th and 17th centuries for their aesthetic value, resistance to disease and perennial foliage. They are now part of our cultural heritage. In addition, they have the ability to survive in an urban environment, meaning they can help attenuate urban heat-islands and reduce air-borne pollution. Caution must be employed when planting such non-native species, but they can have a clear beneficial role in certain contexts," adds the researcher.

Promoting and anticipating

The Geneva study is the first of its type to include an analysis of a broad array of ecosystem services and to encompass both native and non-native species. "Introduced trees are generally listed in the databases of other countries as potential threats, but when it comes to measuring the state of a nation's biodiversity, they are generally dismissed or omitted". The UNIGE research demonstrates that these species provide enormous value and that, as such, they should be integrated into indicators of biodiversity and ecosystem services. "The climate is undergoing profound change, with predictions for our latitudes indicating that within 50 to 100 years - i.e., the life-span of a large tree - the climate in Geneva will be like that in southern Italy. That means we must be open to the idea of introducing species today that are able to persist both now and under future climatic conditions," concludes Dr Schlaepfer.

The chips of the future will include photonics and electronics; they will have a bandwidth, speed and processing and computing abilities that are currently unthinkable; they will make it possible to integrate many other components and their capabilities will increase exponentially compared to electronic chips. In all, they will be essential in many fields; they will bring us a little closer, for example, to quantic computing or to the autonomous car.

The key resides in programmable photonics, a technology in which the Polytechnic University of Valencia (UPV), through the Photonics Research Labs of the iTEAM institute and its spin-off iPronics, programmable photonics SL, is today an international benchmark. This much is confirmed by Nature, which in its latest iteration has published an article that analyses the present and future of this discipline - programmable photonics - signed, among others, by Photonics Research Labs researchers Daniel Pérez and José Capmany.

"Programmable photonics marks a before and an after in the field of telecommunications. It is a field with great potential and value, due to the complementarity it has with electronics. Our article includes all the progress that has been achieved heretofore around the world in this field, which is garnering increased levels of interest," highlights José Capmany.

Democratising photonics

As part of this progress, special mention must go to the generic purpose programmable chips that the UPV research team is working on. These circuits are capable of providing numerous functionalities by using a single structure, in an analogous way to how microprocessors work in electronics. The article also includes the most recent landmarks in the development of chips for specific purposes - designed for a specific task - and mentions the research of European centres such as the University of Ghent and the Polytechnic University of Milan, or American centres such as the MIT, the University of Stanford and the University of Toronto.

"From a fundamental point of view, the article describes and presents the technology of integrated photonics and the different levels required - photonic hardware, control electronics and software - to make the most of the potential of this type of systems," adds Daniel Pérez.

For the UPV researchers, these technologies will make it possible to "democratise" photonics, which would entail a "true revolution" in the field of telecommunications.

"As well as for the autonomous car or quantic computing, integrated photonics will also help improve automated learning systems, 5G communications or the development of neuromorphic computing, with chips that will imitate the network of neurons of our brain and their connections. All these uses require great flexibility and the processing of large amounts of data at high speeds. And this is what programmable photonics offers, and it is what the article published in Nature addresses," highlights Daniel Pérez.

A new study published prior to World Osteoporosis Day finds that the COVID-19 pandemic, which has severely affected management of non-communicable diseases, is markedly impacting the management of osteoporosis as judged by access to online FRAX fracture risk assessments.1,2

Globally, usage of the Fracture Risk Assessment Tool (FRAX®) website was on average 58% lower in April than in February 2020.

FRAX is used to generate 10-year probabilities of fracture at the hip or major skeletal sites using clinical risk factors, with or without bone mineral density (BMD) values. FRAX calculators are available for 66 countries, representing well over 80% of the global population, and the tool is accessed by at least 228 countries/territories worldwide. Widely adopted within clinical guidelines for osteoporosis, FRAX is a key component in the initiation of targeted treatment to reduce the future burden of fractures.

Lead author, Professor Eugene McCloskey, Professor in Adult Bone Disease at the Department of Oncology and Metabolism, University of Sheffield, UK, stated: "As a global tool the FRAX website provides an excellent opportunity to explore the impact of the COVID-19 pandemic on osteoporosis, a major non-communicable disease (NCD) with a significant impact on older adults worldwide."

"The findings of this study reveal that, since the pandemic was officially declared by the WHO on March 11, there has been a dramatic drop in FRAX usage, averaging 58% but ranging up to 96%, with two-thirds of the 66 countries/territories evaluated showing reductions by at least 50%."

The analysis of FRAX usage showed:

Over February-April 2020, the FRAX website recorded 460,495 sessions from 184 countries, with 210,656 sessions in February alone.

In March and April, the number of sessions fell by 23.1% and 58.3% respectively, compared to February 2020, a pattern not observed over the same period in 2019.

In Europe, the majority of countries (24/31, 77.4%) reduced usage by at least 50% in April, with Poland, Slovakia, Czech Republic, Germany, Norway, Sweden and Finland showing smaller reductions (range -2.85% to -44.1%).

In Latin America, all eight countries studied showed reductions greater than 50%, with the smallest reduction seen in Brazil (-54.5%) and the greatest seen in Ecuador (-76.9%).

There were smaller reductions in Asia than elsewhere, partly related to earlier and less-marked nadirs in some countries (China, Taiwan, Hong Kong, South Korea and Vietnam).

There was no significant relationship between the reduction in FRAX usage and measures of disease burden such as COVID-attributed deaths per million of the population.

Metrics of FRAX usage captured by GoogleAnalytics (sessions rather than individual calculations) underestimate actual usage by about 30%, and additionally many FRAX assessments worldwide are conducted on bone densitometers, and were therefore not captured in the study.

As a result, it is estimated that approximately 175,000 patients were likely excluded from fracture risk assessment in April 2020, suggesting that over a 3-month period more than 0.5 million patients would be excluded from assessment, and a significant portion of those from necessary treatment.

Professor John Kanis, IOF Honorary President, Director of the Centre for Metabolic Bone Diseases at Sheffield and Professor at the Catholic University of Australia, stated: "The drastic reduction in FRAX usage underscores widespread concern that the COVID-19 pandemic is having a detrimental impact on the medium to long-term management and outcomes for many NCDs, with serious repercussions for individuals who are not able to access timely testing and treatment, including for osteoporosis."

"Availability and access to bone densitometry in many countries is low to begin with, and access to secondary care-based facilities such as Fracture Liaison Services has been further comprised or inhibited completely during the pandemic. We expect that FRAX, which can be undertaken remotely via telemedicine and has been shown to have a predictive value for fractures that is comparable to the use of bone density values alone, may be able to play a significant role in addressing this enormous backlog in assessments for osteoporosis."

Worldwide demand for food from the tropics that meets higher environmental and social standards has risen sharply in recent years. Consumers often have to make ethically questionable decisions: products may be available to the global market through child labour, starvation wages or environmental destruction. Building on an interdisciplinary project in Peru, an international research team with the participation of the University of Göttingen has now published an overview article on the transition to responsible, high-quality cocoa production. Chocolate is made from cocoa beans, and because cocoa is originally from Peru, using indigenous varieties means a premium price can be charged. A large cooperative for small-holder farmers in northern Peru stands for social and ecological improvements with the help of organic and fair-trade certification, as well as the cultivation of native varieties in species-rich cocoa agroforestry systems. The work was published as a "Perspective" article in the journal Trends in Ecology and Evolution.

Shade trees in traditional cocoa agroforestry systems improve conditions for cocoa growth and promote biodiversity, for instance of birds. However, these trees are increasingly being removed to increase productivity, even though moderate, partial shade does not significantly reduce productivity. In addition, proven high-yielding varieties are imported, although there are unique indigenous varieties in Peru that may be associated with a particular trade advantage. The researchers' project group is working together with the cooperative Norandino Ltda. in Piura, northern Peru, which is committed to working towards developing high social and ecological standards. It represents 5,400 smallholder farmers and stands for sustainable production that pursues both ecological and economic goals. Furthermore, the cooperative is committed to fighting all forms of discrimination. The result is ecologically certified and fair-trade chocolate of a high standard, which achieves up to twice the regular market price, protects smallholder farmers against market fluctuations and moves towards the greater use of local cocoa bean varieties in the future.

Dr Bea Maas, first author of the article and now at the University of Vienna, emphasises: "Large cooperatives that stand for high social, economic and ecological standards in production should receive more support." Carolina Ocampo-Ariza and Professor Teja Tscharntke from the Agroecology group at the University of Göttingen add: "Such exemplary initiatives that benefit the livelihoods of smallholder farmers while maximising nature conservation should be the focus of interdisciplinary research now more than ever before."