Culture

At some point in life, most people have stood over a rolled-out slab of cookie dough and pondered just how to best cut out cookies with as little waste as possible. Now, even math experts have given up on finding a computer algorithm to answer this type of geometric problem.

How can we maximize dough while cutting out Christmas cookies? How do we pack a suitcase or fill a kitchen cabinet while making the best use of space? One may have thought, "there must be a best way to do this." Pondering such questions too deeply now appears to be a complete waste of time. The science is now here to support that it is impossible, for the time being, to figure out what works best for more than four or five spicy gingerbread men or Christmas tree cookies.

Assistant Professor Mikkel Abrahamsen of the Department of Computer Science and two research colleagues studied how difficult it is to figure out the optimal way to pack objects in two dimensions without overlap -- a conundrum that computer scientists have plugged away at for decades.

"While algorithms let us solve seriously complex problems, this is one that remains too much of a mouthful for today's computers. For now, it isn't possible to pack more than 5-10 objects optimally. And, our result suggests that this number probably won't increase much for the time being," explains Mikkel Abrahamsen.

Packing things optimally isn't just an occasional problem at home, but in a variety of industries, including clothing manufacturing and metal processing. In each case, it is important to cut out materials with as little waste possible. In shipping, it applies to the packing of containers.

Only four gingerbread cookies

We know the size of the smallest square container in which we can pack up to 10 square 1x1 meter pallets. But by simply adding one additional pallet, it becomes impossible to calculate the optimal size of the container. Abrahamsen explains:

"As more pallets are added, the calculation time increases beyond exponentially. Not even the best computers can keep up. Theoretically it's possible. But based upon the speed at which computing power is growing, it will probably take millions of years before we are able to optimize the handling of a few additional objects."

Furthermore, if one is working with more complicated shapes, like Christmas tree-shaped gingerbread, Mikkel Abrahamsen says that optimal solutions can only be found for up to four objects today.

An infinite number of options

What makes it so difficult? Abrahamsen explains that the problem is similar to solving equations of degree five or higher, and with many unknowns. Here, it is known that such a solution cannot always be written down using regular arithmetic operations.

"Our study proves that the problem has a nature that we in mathematics refer to as continuous -- which in a nutshell, means that one must know all of the coordinates at which the cookies can be placed and all of the angles at which they can be rotated," explains Abrahamsen.

As the possible combinations are infinite, there is no way to create a list of all the locations needed to try in order to find an optimal packing solution. Instead, algorithms that solve packing problems optimally need to be more analytical, which is time consuming. This contrasts with many other known algorithmic problems, where one can try a limited number of combinations before finding one that is optimal. Thus, packing problems are much more difficult.

So in practice, there are no better solutions to packing problems than the ones we humans can come up with.

"In both industry and over the kitchen counter we must continue to be satisfied with our less-than-optimal solutions and rest assured that we humans are still better than computers for these types of tasks -- for the time being," concludes Mikkel Abrahamsen.

The mangrove forests on Java's north coast are slowly suffocating in plastic waste. The plastic problem in northeast Asia is huge and a growing threat to the region's mangroves; a natural alley against coastal erosion. Based on fieldwork published in Science of the Total Environment, NIOZ researcher Celine van Bijsterveldt shows that restoration of this green protection belt is impossible without better waste management

Plastic trap

Van Bijsterveldt has monitored the accumulation of plastic waste in Indonesian mangroves over years. Most of it includes household litter, carried from the inland to the coastal area by local rivers. Ultimately, the waste gets stuck in the last stronghold between land and sea. Van Bijsterveldt: 'Mangroves form a perfect plastic trap.' For the mangrove tree, this trap can become quite lethal. The most common mangrove tree on Java's coast, the grey mangrove, has upward-growing roots to get oxygen flowing during high tide. 'You can look at these roots as snorkels,' says Van Bijsterveldt. 'When plastic waste accumulates in these forests, the snorkels are blocked.' In areas completely covered by plastic, trees suffocate.

On the forest floor of mangroves along the north coast, it is hard to find a square metre without plastic. 'On average, we found 27 plastic items per square metre,' recounts Van Bijsterveldt. At several locations, plastic covered half of the forest floor. The problem isn't only the plastic on the surface. The team found plastics buried as deep as 35 cm inside the sediment. Plastic, stuck in these upper layers further decreases the trees access to oxygen. Still, Van Bijsterveldt was impressed by the trees' resilience. 'The roots change course when they are obstructed. They grow around the plastic. When half of the forest floor is covered, the tree still gets enough oxygen to keep its leaves.' However, the prospect of survival gets much gloomier once the threshold of 75 % is reached and plastic in the sediment pushes it towards 100%. 'We've seen roots stuck inside plastic bags. Trying to find a way out, they just grow in circles. Eventually trees that cannot outgrow the plastic die.'

Battling erosion and breaking waves
In cooperation with NGO's and local communities, Van Bijsterveldt works on mangrove restoration projects to prevent further erosion. Over the years many mangrove forests had to make way for rice paddies and later aquaculture ponds. A business model that brings fast profits but lacks in sustainability as it accelerates erosion. Not a small problem in a region threatened by coastal loss and rapid subsidence, and no financial means to build high-cost and high-maintenance solutions like dykes. Van Bijsterveldt: 'Mangroves form a low-cost, natural defence for the coastal communities. They act like wave breakers and can prevent erosion by trapping sediment from the water.'

Restoration brings more benefits. Healthy mangroves mean healthy fish populations and a sustainably fishing economy. The tourism industry is also discovering the forests as a growing attraction that boosts the local economy. The Indonesian government is investing in mangrove restoration in an attempt to re-create a green-belt along the coast. But restoration is slow and existing forests are stressed. Van Bijsterveldt, saw attempts of planting new mangroves fail: 'There is so much focus on increasing the initial number of mangrove seedlings, that the challenges posed by plastic waste on the actual survival of young trees is overlooked'. Replanting mangroves without tackling the plastic problem is like trying to try to empty the ocean with a thimble. Successful restoration needs to go hand in hand with sustainable waste management.'

Some useful drugs consist of peptides acting on their protein targets. To make them more efficient and stable, scientists have found a way to replace crucial segments of the peptides with ureido units. These oligoureas, which are composed of urea-based units, fold into a structure similar to that of peptides. Oligourea-based "fake" peptides enhance the options for rational drug design, concludes the study published in the journal Angewandte Chemie.

Several drugs are peptides that inhibit or activate the actions of certain proteins. To enhance their efficiency, scientists are investigating peptide mimics. Peptide mimics contain strands of small organic units that resemble amino acids--the building blocks of peptides--but are not identical to them. The rationale is that proteolytic enzymes will less likely attack such fake peptide strands, so the drugs would be more effective.

However, the synthetic strands--called oligomers--must fold into the structure of the original peptide to bind to its target protein properly. Gilles Guichard and his team from CNRS, University of Bordeaux, and colleagues from the University of Strasbourg and Ureka Pharma, Mulhouse, France, have explored oligomers made of ureido units, which are derivatives of urea. These oligoureas fold into a helix, one of the hallmark structures of peptides. However, there are slight differences. "Oligourea helices have fewer residues per turn, a smaller rise per turn, and a larger diameter than the original peptide alpha-helix," says Guichard.

To determine whether oligoureas could mimic real peptide structures, the researchers prepared peptide-oligourea hybrids and investigated their binding to target proteins. One of the targets, MDM2, is a natural regulator of the tumor suppressor protein p53. The other one, VDR, is a protein required in the regulation of cell growth, immunity, and other biological functions.

For the MDM2-binding peptide mimic, the researchers prepared hybrids by replacing three terminal key amino acids with ureido units. For the VDR-binding peptide mimic, they replaced the middle amino acid segment with ureido units. After some rounds of optimization, the authors found hybrid structures with high binding affinities.

The binding affinities were similar to those of the original peptides. Moreover, X-ray analysis revealed that the hybrid structures adopted a regular helical structure. However, the helices were still a bit wider and had larger spaces between the side chains along the oligourea backbone than those of natural peptides.

Peptide-oligourea hybrids are expected to resist proteolytic degradation, an important goal in medicinal chemistry. Another advantage is that they allow more modifications. "Alpha amino acids can be substituted at two positions, but ureido units have one site more," says Guichard. This means that hybrid peptide-oligourea drugs offer more options for optimization.

Guangzhou, December 5, 2020: New journal BIO Integration (BIOI) publishes its third issue, volume 1, issue 3 which is a themed issue on the integration of artificial intelligence (AI) in medicine and biomedicine. BIOI is a peer-reviewed, open access, international journal, which is dedicated to spreading multidisciplinary views driving the advancement of modern medicine. Aimed at bridging the gap between the laboratory, clinic, and biotechnology industries, it will offer a cross-disciplinary platform devoted to communicating advances in the biomedical research field and offering insights into different areas of life science, in order to encourage cooperation and exchange among scientists, clinical researchers, and health care providers.

Featured papers in this issue:

The first featured article in this issue is an opinion article entitled "New Roles for Clinicians in the Age of Artificial Intelligence" by authors Fengyi Zeng, Xiaowen Liang and Zhiyi Chen. Artificial intelligence (AI) has been widely applied in the medical field. Barely a day goes by without a claim that AI techniques are poised to replace most of today's professionals. The integration of AI in medicine has necessitated the exploration of new roles for clinicians in the age of AI.

The second featured article in this issue is a review article entitled "Artificial Intelligence (AI)-aided Disease Prediction" by Chenxi Liu, Dian Jiao and Zhe Liu. Artificial intelligence (AI) used in clinical medicine is witnessing increasing innovations in the fields of AI-aided image analysis, AI-aided lesion determination and AI-assisted healthcare management. This review article focuses on the emerging applications of AI-related medicine and AI-assisted visualized medicine, including novel diagnostic approaches, metadata analytical methods, and versatile AI-aided treatment applications in preclinical and clinical uses, and also looks at future perspectives of AI-aided disease prediction.

The third featured article in this issue is a review article entitled "A Survey on Artificial Intelligence in Chest Imaging of COVID-19" by Yun Chen, Gongfa Jiang, Yue Li, Yutao Tang, Yanfang Xu, Siqi Ding, Yanqi Xin and Yao Lu. Chest imaging techniques including computed tomography and X-ray scans are indispensable tools in COVID-19 diagnosis and its management. The strong infectiousness of this disease brings a huge burden for radiologists. In order to overcome the difficulty and improve accuracy of the diagnosis, artificial intelligence (AI)-based imaging analysis methods are explored. This survey focuses on the development of chest imaging analysis methods based on AI for COVID-19 in the past few months. Imaging analysis methods of two typical viral pneumonias are reviewed, which can provide a reference for studying the disease on chest images.

Other articles published in the issue include:

Editorial

An Integrated Approach to Ultrasound Imaging in Medicine and Biology
Pingtong Huang

Original Article

Scale-aware Auto-context-guided Fetal US Segmentation with Structured Random Forests
Xin Yang, Haoming Li, Li Liu and Dong Ni

News and Views

BIOI Virtual Academic Series PART 2: Frontiers and Multidisciplinarity in Nanomedicine
Phei Er Saw

As the global population grows and ages, so does their need for eye care. But according to two new studies published in The Lancet Global Health, these needs aren't being met relative to international targets to reduce avoidable vision loss.

As 2020 comes to a close, an international group of researchers set out to provide updated estimates on the number of people that are blind or visually impaired across the globe, to identify the predominant causes, and to illustrate epidemiological trends over the last 30 years.

"This is important because when we think about setting a public health agenda, knowing the prevalence of an impairment, what causes it, and where in the world it's most common informs the actions that key decision makers like the WHO and ministries of health take to allocate limited resources," says Joshua Ehrlich, M.D., M.P.H., a study author and ophthalmologist at Kellogg Eye Center.

The study team assesses a collection of secondary data every five years, undertaking a meta-analysis of population-based surveys of eye disease assembled by the Vision Loss Expert Group and spanning from 1980 to 2018.

Creating a blueprint

A study like this poses challenges since regional populations vary in age.

"For example, the population in some Asian and European countries is much older on average than the population in many African nations. Many populations are also growing older over time. A direct comparison of the percentage of the population with blindness or vision impairment wouldn't paint a complete picture" says Ehrlich, who is also a member of University of Michigan's Institute for Healthcare Policy and Innovation, explains.

To address this issue, the study looked at age-standardized prevalence, accomplished by adjusting regional populations to fit a standard age structure.

"We found that the age-standardized prevalence is decreasing around the world, which tells us eye care systems and quality of care are getting better," says study author Monte A. Del Monte, M.D., a pediatric ophthalmologist at Kellogg Eye Center. "However, as populations age, a larger number of people are being affected by serious vision impairment, suggesting we need to improve accessibility to care and further develop human resources to provide care."

In fact, the researchers found that there wasn't any significant reduction in the number of people with treatable vision loss in the last ten years, which paled in comparison to the World Health Assembly Global Action Plan target of a 25% global reduction of avoidable vision loss in this same time frame.

Although findings varied by region globally, cataracts and the unmet need for glasses were the most prevalent causes of moderate to severe vision impairment. Approximately 45% of the 33.6 million cases of global blindness were caused by cataracts, which can be treated with surgery.

Refractive error, which causes a blurred image resulting from an abnormal shape of the cornea and lens not bending light correctly, accounted for vision loss in 86 million people across the globe. This largest contributor to moderate or severely impaired vision can be easily treated with glasses.

Also important, vision impairment due to diabetic retinopathy, a complication of diabetes that affects eyesight, was found to have increased in global prevalence.

"This is another condition in which we can prevent vision loss with early screenings and intervention," says study author Alan L. Robin, M.D., a collaborating ophthalmologist at Kellogg Eye Center and professor at Johns Hopkins Medicine. "As diabetes becomes more common across the globe, this condition may begin to affect younger populations, as well."

Looking to 2050

"Working as a global eye care community, we need to now look at the next 30 years," Ehrlich says. "We hope to take these findings and create implementable strategies with our global partners through our Kellogg Eye Center for International Ophthalmology so fewer people go blind unnecessarily."

In an effort to contribute to the WHO initiative VISION 2020: The Right to Sight, the researchers updated estimates of the global burden of vision loss and provided predictions for what the year 2050 may look like.

They found that the majority of the 43.9 million people blind globally are women. Women also make up the majority of the 295 million people who have moderate to severe vision loss, the 163 million who have mild vision loss and the 510 million who have visual impairments related to the unmet need for glasses, specifically poor near vision.

By 2050, Ehrlich, Del Monte, and Robin predict 61 million people will be blind, 474 million will have moderate and severe vision loss, 360 million will have mild vision loss and 866 million will have visual impairments related to farsightedness.

"Eliminating preventable blindness globally isn't keeping pace with the global population's needs," Ehrlich says. "We face enormous challenges in treating and preventing vision impairment as the global population grows and ages, but I'm optimistic of a future where we will succeed because of the measures we take now to make a difference."

NORFOLK, Va. -- After more than three years in development, a team of U.S. Army researchers and industry partners completed the construction of a testbed that will help to inform the design of future Army rotorcraft.

The team plans to test the TiltRotor Aeroelastic Stability Testbed, or TRAST, in a massive wind tunnel at the NASA Langley Research Center to gauge the effectiveness of modern tiltrotor stability models.

"This research effort is to gain confidence in Future Vertical Lift vehicles that are aimed at a tiltrotor configuration," said Andrew Kreshock, an Army aerospace engineer at the U.S. Army Combat Capabilities Development Command, now known as DEVCOM, Army Research Laboratory. "Since future vehicles are being developed without wind tunnel testing, this puts more pressure for accurate stability predictions."

Tiltrotors offer enormous potential for the Army in terms of speed and vertical lift capability. Unlike most aircraft, they can hover in the air like a helicopter or fly forward at great speeds like an airplane depending on the orientation of their rotors.

The ability to transition between the two modes allows tiltrotors to capitalize on the advantages of both rotorcraft and fixed-wing aircraft depending on the situation.

"Currently, the max speed of conventional helicopters is around 160 to 180 knots," Kreshock said. "Tiltrotors can achieve 300 knots. We're looking at almost doubling the speed of our current fleet and thus increasing our range by almost twice as much in the same flight time."

But despite its versatility, tiltrotors face severe stability issues due to the placement of incredibly heavy engines with large rotors on the end of the wings.

The interaction between the propellers and the wings can generate a dangerous phenomenon known as whirl flutter, where strong aerodynamic forces cause the airframe structure to shake violently and even fail.

As a result, tiltrotors are difficult to construct properly, and researchers continue to validate tools necessary to predict how different tiltrotor configurations will fare against whirl flutter.

According to Kreshock, TRAST serves to help researchers develop state-of-the-art analysis software that open the possibilities for new tiltrotor designs.

"Helicopters have gone through many generations from when they were first built to now, but the only tiltrotor in production is the V-22 Osprey," Kreshock said. "And the tools developed for predicting stability in the V-22 were made in the 1960s and 1970s. Because we have better computers now, we can model as many degrees of freedom as we need compared to the tools from decades ago."

In order to predict whirl flutter behavior in TRAST, Kreshock and his team employed different analysis codes for different parts of the tiltrotor structure.

They used a structural code called NASA Structure Analysis, or NASTRAN, to model the aerodynamics of the wing and two different programs--the Comprehensive Analytical Model of Rotorcraft Aerodynamics, or CAMRAD, and the Rotorcraft Comprehensive Analysis System, RCAS--to model the rotorcraft.

Through the combination of these three programs, the team isolated the aerodynamic behavior of individual aircraft components and then used this information to estimate the stability boundaries of the TRAST model.

Once the researchers test the TRAST model in the wind tunnel, they can compare how well the predictions generated by the analysis codes match the actual behavior of TRAST in the face of extreme whirl flutter.

"We want to measure the stability boundary without actually breaking the model," Kreshock said. "It's tricky because as you start getting closer to the stability boundary, you can watch the model vibrate and become more unstable. As we watch this model shake from the window, we have to make sure to keep one finger on the switch to shut down the wind tunnel before the model actually breaks."

According to Kreshock, present tiltrotors like the V-22 Osprey handle the issue of whirl flutter through reinforced airframes and thick airfoils, which severely increase the weight of the aircraft.

He believes that TRAST may help the Army explore new design possibilities for tiltrotors that resolve the whirl flutter problem in different ways, such as wing extensions.

"Compared to civilian aircraft, the Army always pushes their aircraft to the limit," Kreshock said. "In order to meet this demand, we need to improve the stability predictions so that we not only have more efficient aircraft but also be able to test new technology in the future."

Each and every biological organism has an important function in creating a healthy ecosystem, which is why conservationists everywhere encourage protecting biodiversity. However, monitoring wildlife health is an ongoing challenge. A new article in Environmental Toxicology and Chemistry explores the use of a simple, inexpensive, and minimally invasive technique referred to as "micronuclei detection" to assess genetic toxicity (genotoxicity) in free-ranging bats in areas of varying agricultural activity.

Bats play a vital role in our ecosystems and economies as natural pest control agents, seed dispersers, and pollinators. Bats are susceptible to pesticide exposure, especially if they forage near agricultural lands and prey on contaminated pests. Additionally, pesticide applications often take place at dusk when bats are most active.

To evaluate the potential effects of pesticides on bats, Author Natalia Ivone Sandoval Herrera and colleagues collected blood samples from 35 bats* across three roosting caves in Mexico that were surrounded by different levels of agricultural activity. They examined the occurrence and magnitude of damage to genetic material (genotoxicity) in bat cells by measuring the frequencies of micronuclei in the bats. Micronuclei frequency is an index of accumulated genetic damage during the life span of the cells, so higher frequency levels would be expected in bat populations inhabiting areas with more intensive agriculture. In fact, that is exactly what the authors found. The bats roosting in sites surrounded by agricultural lands presented higher frequency of micronuclei compared with bats inhabiting sites with lower agricultural activity. The work showed that this testing method can have wide applications as an inexpensive and minimally invasive technique to evaluate genotoxicity in animals and monitor wildlife health.

Biodiversity is decreasing world-wide, and it is likely due to anthropogenic activities. It is critical to have methods to monitor wildlife population health, because protective and remedial measures are better for maintaining biodiversity than post-mortem assessments. Micronucleus testing does not require expensive equipment and training. Additionally, while there are more sophisticated methods to evaluate genotoxicity, they are not necessarily more sensitive. When asked why we should be paying attention to this testing method, Sandoval Herrera said, "Access to resources might be limited for institutions with less financial support such as conservation NGOs and researchers in developing countries. The use of early warning biomarkers such as genotoxic effects are most needed in these regions, where the use of pesticides is extensive and there is high biodiversity. This test as a logistically simple, sensitive, and robust method for biomonitoring genotoxic effects in wild bat populations."

In a recent study, Alexander von Humboldt Professor Jijie Chai at the University of Cologne and his team together with MPIPZ researchers have succeeded for the first time in reconstructing the sequence of molecular events that activate an inactive plant immune receptor and thus mediate the death of the host cell. The researchers' discoveries are of great importance for understanding how these critical plant immune molecules protect their hosts from infections. The configuration adopted by the activated protein is similar to that of other plant and mammal receptors, including humans. This suggests that these receptors are based on a common structural principle to trigger intracellular immune signals and cell death in different areas of life.

The scientists describe their results in the article 'Direct pathogen-induced assembly of an NLR immune receptor complex to form a holoenzyme' in Science.

Although separated by millions of years of evolution, plants and animals have independently developed similar immune strategies to protect themselves against microbial infections. In both kingdoms of life, immune receptors called nucleotide-binding/leucine-rich repeat proteins (NLR proteins) form an important defence layer within cells against pathogen attack. NLRs are complex devices consisting of several modules. These modules recognize the molecules (effectors) of invading microbes. Effectors trigger the immune response of the plant - they activate receptors, resistance and cell death pathways to limit infection. Based on different structural and signalling characteristics, plant NLRs are divided into two main classes: those that contain coiled-coiled (CC) modules (CNL proteins) and those that contain toll/interleukin-1 receptor/resistance (TIR) modules (TNL proteins).

The scientists conducted their research on the model organism Arabidopsis thaliana, or thale cress. Jijie Chai, together with the MPIPZ research group leader Jane Parker and MPIPZ dirctor Paul Schulze-Lefert, determined the structural and biochemical features underlying the activation of a specific receptor: the so-called TNL type NLR Receptor of Peronospora parasitica 1 (RPP1). It protects the model plant against infection with the fungus Hyaloperonospora arabidopsidis (Hpa).

To understand how RPP1 protects plants on the molecular level from Hpa infection, the team generated RPP1 protein together with the known Hpa effector ATR1 . The RPP1 receptor activated in this way is an enzyme that breaks down nicotinamide adenine dinucleotide (NAD+), which is important for defence signalling.

By isolating RPP1-ATR1 complexes and subjecting them to cryo electron microscopy, the authors have answered two open questions of NLR biology: first, how direct binding of the effector to the NLR receptor induces the activation of a receptor. Secondly, they determined that the TNL receptor in this case organizes itself as a so-called tetramer, a molecule consisting of four tightly packed receptor molecules. Tetramers belong to the group of oligomeric molecules, which are all structurally made up of similar units. The observed tetramer creates a unique surface within a part of the receptor, which is necessary for the cleavage of NAD+ to trigger defence signals.

The effector ATR1 induces tetramerization at one end of RPP1 and simultaneously forces the above-mentioned four TIR modules at the opposite end of the molecule to form two asymmetric TIR pairs that degrade NAD+.

Strikingly, the results of the groups around Eva Nogales and Brian Staskawicz at the University of California, Berkeley, on another NLR of the TNL type, Roq1 from the tobacco relative Nicotiana benthamiana, also show that TNL activation involves direct effector recognition and adoption of a similar tetrameric structure. The effector recognized by Roq1 is produced by a bacterial pathogen and the activated Roq1 receptor complex provides resistance to bacterial infections. Therefore, the discoveries of Jijie Chai, his team and the MPIPZ researchers seem to be of great importance for understanding how these critical plant immune molecules protect their hosts from infections. More generally, the oligomeric configurations adopted by active RPP1 and Roq1 resemble the induced oligomeric scaffolds of other plant and mammalian NLR receptor proteins, including human innate immune receptors. This suggests that these receptors are based on a common structural principle to trigger intracellular immune signals and cell death in different kingdoms of life.

More local law enforcement agencies are using military equipment, such as tear gas, armored vehicles and rubber bullets, to handle social justice protests--calling into question police militarization.

But if police no longer used weapons and tactics previously connected to the military, there is little evidence that this would impact violent crime or officer safety, according to a new University of Michigan study.

In fact, previous data analyses supporting officers taking on the appearance and using weapons like soldiers as a crime-reduction method are unreliable, said U-M researcher and study author Kenneth Lowande. The data problems also impact studies that claim military equipment make police more violent.

In a report published today in Nature Human Behaviour, Lowande examined the substantial limitations of data used to analyze the effects of transferring surplus military equipment, or SME, to law enforcement.

Federal authorities have subsidized weapons and equipment acquisition, but limitations in record keeping about these transfers have rendered studies of their effects not credible, he said. The current study examined 3.8 million archived federal inventory records to gauge the reliability in these other studies.

During a typical three-month period, more than 15,000 controlled items vanish from agency inventories and more than 4,000 are received for transfer, the study indicated.

Lowande, U-M assistant professor of political science, compared this data to data collected when the Obama administration recalled SME in 2015, which resulted in a forced demilitarization of several hundred police departments. Proponents of SME transfers, as well as the Trump administration, say that demilitarization would lead to an increase in violent crime, but that's now what Lowande found.

"When you examine crime and officer safety statistics in these demilitarized departments and compare them to similar departments that weren't impacted, you find essentially no differences," said Lowande, a faculty associate at the Center for Political Studies at U-M's Institute for Social Research.

"I find little to no evidence that demilitarization had an impact on violent crime or officer safety. Put differently, contrary to the claims of those who support the transfer of equipment, these data do not support the conclusion that militarization saves lives--or that demilitarization risks them."

BEER-SHEVA, Israel...December 7, 2020 - According to a new study by Ben-Gurion University of the Negev (BGU) researchers, the natural sweetener stevia may lead to a gut microbial imbalance. The findings were just published in Molecules, a leading international peer-reviewed journal of chemistry.

Stevia is a natural low-calorie sweetener that is growing in popularity in food and beverage products and is generally considered safe. However, emerging scientific evidence has implicated the sweetener in gut microbial imbalance, which can lead to a variety of gastrointestinal health issues.

According to the new study, stevia may disrupt communications between different bacteria in the gut microbiome. While the team found that stevia inhibited these pathways, it did not kill off the bacteria.

"This is an initial study that indicates that more research is warranted before the food industry replaces sugar and artificial sweeteners with stevia and its extracts," says lead researcher Dr. Karina Golberg, of the BGU Avram and Stella Goldstein-Goren Department of Biotechnology Engineering.

Large amounts of new particles can form in the valleys of the Himalayas from naturally emitted gases and can be transported to high altitudes by the mountain winds and injected into the upper atmosphere.

The emitted particles may eventually affect climate by acting as nuclei for cloud condensation. These new findings about particles formation and sources will contribute to a better understanding of past and future climate.

"To understand how the climate has changed over the last century we need to know as reliably as possible the natural atmospheric conditions before the industrialization," says Associate Professor Federico Bianchi from the University of Helsinki's Institute for Atmospheric and Earth System Research (INAR).

In order to do that scientists are looking for pristine locations around the world where human influence is minimal. An international group of researchers has now completed a comprehensive study at the Nepal Climate Observatory at Pyramid station, located in the proximity of the Everest base camp at 5050 m above sea level. There, they were able to investigate the formation of atmospheric particles far from human activities. The results were published today in the prestigious journal Nature Geoscience.

Particles from natural origin

The study shows that up-valley winds bring vapours emitted by vegetation at the Himalayan foothills to higher altitudes. During this transport, these gases are transformed by photochemical reactions into compounds of very low volatility, which rapidly form a large number of new aerosol particles. These are then transported into the free troposphere, a region of the atmosphere with very low human influence.

"You can think of the whole Himalayas as an 'aerosol factory' that continuously produces a large amount of particles and then directly injects them high up into the atmosphere above the Everest", says Bianchi. We calculate from these measurements that the transport of particles may increase present-day particle concentration above the Himalayas by a factor of up to two or more.

It's the first time the scientists consider mountain venting as a big potential source of atmospheric particles in the free troposphere.

Additionally, the freshly formed particles have natural origin with little evidence of the involvement of anthropogenic pollutants. This process is therefore likely to be essentially unchanged since the pre-industrial period, and may have been one of the major sources contributing to the upper atmosphere aerosol population during that time. These new observations are therefore important to better estimate the pre-industrial baseline of aerosol concentrations in this large region. The inclusion of such processes in climate models may improve the understanding of climate change and predictions of future climate.

Future studies shall focus on a better quantification of this phenomenon and investigate it also in other high mountain regions.

According to a biologist from RUDN University, fern leaves powder has a positive effect on the immune system, antimicrobial activity, and growth of carps. Based on this data, fish farms can breed big and healthy fish without using any chemical additives. An article about the work was published in the Fish & Shellfish Immunology journal.

Cyprinus carpio or common carp accounts for 7.7% of world fish production (around 4.2 mln tons). Because of the increasing production volumes, fish farms become overcrowded which causes stress in the fish. This, in turn, slows down their growth, weakens their immune systems, promotes infections, and eventually causes financial damage to the farmers. Infectious diseases can be fought with chemical additives, but they accumulate in the bodies of the fish leading to drug resistance in the next generations which can be harmful to consumers. A biologist from RUDN University suggested improving the immunity of the fish by adding fern leaves powder to their diet. An experiment conducted by his team confirmed the efficiency of this natural additive and showed no side effects from it.

"Many studies on the effect of plant extracts on fish have been conducted in recent years. Plant additives show positive results because they contain certain biologically active components: essential oils, alkaloids, saponins, phenols, flavonoids, and polysaccharides. In our work, we focused on Adiantum fern that has been known for its beneficial pharmacological properties since ancient times. For example, the extract of its leaves showed antibacterial activity against S. aureus and E. coli," said Morteza Yousefi, PhD., an assistant professor at the Department of Veterinary Medicine, RUDN University.

The team conducted an experiment to study the effect of Adiantum capillus-veneris on the health of fish. To do so, they distributed 144 carps between 12 pools and developed different diets (with three feedings per day) for each group. All diets were based on fish, wheat, and soy flour, fish oil, and a set of minerals and vitamins. Dried and powdered fern leaves were added to nine diets with their share varying from 0.5% to 2% of the total weight of the fodder. Then, the team monitored the growth of the fish and the activity of their immune systems for 56 days. After that, the biologists measured the levels of immunoglobulin in the blood serum and skin mucus of the fish, the activity of the antibacterial enzyme lysozyme, and other parameters.

Lysozyme activity turned out to grow with the increase of the share of fern in the diet. While the addition of 0.5% had practically no impact on the work of the enzyme, 2% made it almost twice as active, increasing its levels from 4.6 to 8 units per ml. The addition of fern powder also supported the antibacterial activity of blood serum against some pathogens, such as S. aureus, E. coli, and Ps. aeroginosa. Moreover, the fish with 2% fern powder in their diet gained the most weight: 27.7 g on average against 19.6 gained by the fish that did not receive fern at all.

"The results of our work clearly demonstrate the positive effect of Adiantum capillus-veneris on the immunity of common carp juveniles. However, further research on the molecular level is required to identify the exact mechanism of its influence on growth indicator, stress resistance, and immune parameters of the fish," added Morteza Yousefi from RUDN Univerisity.

Athens and Patras, December 7, 2020- Caregivers of people with dementia and milder forms of neurocognitive disorder bear a heavy burden. They are constantly confronted with challenging symptoms and behaviors and feel they are up against their limits. The latest results from a study indicate that the COVID 19 crisis affects this burden since the pandemic has mental health implications.

Scientists and clinicians from the universities of Athens and Patras and the Corporation for Succor and Care of Elderly and Disabled-FRODIZO studied the impact of the COVID19 pandemic on caregiver distress. They contacted during the first lockdown in Greece carers of people with a neurocognitive disorder of the psychogeriatric unit at the Eginition Hospital in Athens, the Patras dementia day center, and the psychogeriatric department for neurocognitive assessment at the Patras office of the Hellenic Red Cross. Based on a standardized questionnaire, they asked caregivers over the telephone about difficulties of patients with memory function, neuropsychiatric symptoms such as depressive mood, sleep problems or anxiety, and last but not least about patients' problems with everyday activities (e.g., preparing meals, managing household, personal hygiene). In addition, caregivers depicted their distress due to these symptoms and reported their feelings and worries regarding the COVID19 crisis. Symptoms related to the pandemic, such as feeling on guard, trouble falling asleep, or concentrating, were significantly associated with caregiver distress due to dementia symptoms. "This clear association highlights the effect of the pandemic on the way difficulties of dementia care are encountered" underscores associate professor Panagiotis Alexopoulos, Department of Psychiatry at the Patras University Hospital at the University of Patras. Progression of memory deficits and neuropsychiatric symptoms also pertained significantly to caregiver burden.

"Our observations are an alarming voice for the support needs of caregivers of people with the neurocognitive disorder during the COVID-19 pandemic since they seem to belong to the hidden victims of the current crisis," states professor Antonios Politis, head psychiatrist of the old age mental health services at the Eginition Hospital at the University of Athens.

New research shows that the militarization of local law enforcement through weapons, armored vehicles, combat attire, office equipment and other items provided by the Department of Defense does not reduce crime. Additionally, researchers found incomplete records and discrepancies in the federal government's tracking of surplus military equipment, or SME, issued to local law enforcement agencies.

"Scholars rely on accurate data to track and analyze the true effect of police militarization on crime. Policymakers also need accurate data to base their decisions upon. However to-date, we do not have reliable data on SME transfers to local police and sheriffs through the federal government," said LSU Department of Political Science Assistant Professor Anna Gunderson, who is the lead author on a paper published today in Nature Human Behaviour.

In 2014 following the police brutality protests in Ferguson, President Obama prohibited local law enforcement agencies from procuring some of the most military-like equipment, such as tracked armored vehicles and grenade launchers, from the Department of Defense. In 2017, President Trump reversed this order citing research that claimed police militarization reduces crime. Three years ago, Gunderson and coauthors at Emory University began interrogating newly released data on SME provisions through the 1033 program, which is one of the most significant federal programs that contributes to the militarization of local police and sheriffs.

"When we looked at the data and ran the replications, nothing looked like the results being cited by the Trump Administration. We spent a year trying to diagnose the problem," Gunderson said.

She and her coauthors found significant discrepancies in the data about which law enforcement agencies have and use SME. The researchers compared a 2014 data release from National Public Radio, or NPR, and newer data from 2018 and found inconsistencies between them. For example, the NPR data recorded counties as receiving equipment like weapons, with no corresponding record in the 2018 data; and the 2018 data show some counties as receiving equipment while those counties are missing in the NPR data.

The researchers conclude that drawing firm conclusions and promoting claims about the efficacy of police militarization--especially for crime rates--based on research relying on the SME data released by the Department of Defense is unreliable. When they conducted a new analysis using updated data, the authors found no evidence that SME transfers reduce crime.

"This is a cautionary tale about the importance of oversight. The most important thing for policy makers and the public to know is that you can't justify giving surplus military equipment to police departments on the grounds it will lead to a reduction in crime. There is no evidence for that. You can't claim this program is important because it reduces crime," said co-author Tom Clark, Charles Howard Candler Professor of Political Science at Emory. "If you are going to engage in policy making experiments, it is important to include resources and requirements for reporting so that policy analysts can study whether the policy is working."

Researchers at the University of Illinois Urbana Champaign have developed a new technique that combines label-free imaging with artificial intelligence to visualize unlabeled live cells over a prolonged time. This technique has potential applications in studying cell viability and pathology.

The study "Phase imaging with computational specificity (PICS) for measuring dry mass changes in sub-cellular compartments" was published in Nature Communications.

"Our lab specializes in label-free imaging, which allows us to visualize cells without using toxic chemicals," said Gabriel Popescu, a professor of electrical and computer engineering and the director of the Quantitative Light Imaging Laboratory at the Beckman Institute for Advanced Science and Technology. "However, we cannot measure specific attributes of the cell without using toxic fluorescent dyes. We have solved that problem in this study."

"We had this idea that computational methods could estimate what the sample would look like without actually killing the cells," said Mikhail Kandel, a graduate student in the Popescu group.

The researchers first imaged the cells over several days using their non-destructive label-free technique. At the end of the experiment, they stained the samples and used deep learning, which is a subset of machine learning, to learn where the fluorescence dyes would be located. "This let us estimate the stain in our initial movies without actually staining the cells," Kandel said.

"Although AI has been used in the past to create one type of imaging from a different type of staining, we were able to program it to analyze the images in real time," Popescu said. "Using deep learning, we were able to look at cells that had never been tagged with any dye, and the algorithm was able to precisely locate different parts of the cell."

"Another advantage of the technique is that we can perform experiments over the span of many days. The cells remain alive even after more than a week," said Yuchen He, a graduate student in the Popescu group. "This cannot be done with fluorescent dyes since the chemical toxicity might kill the cells."

"This study highlighted the potential of AI-based techniques to learn complicated models such as the concentration of specific dyes, which goes beyond the capabilities of the naked eye," Kandel said. "The more we can teach our method to recognize patterns, the more kinds of experiments can be performed without resorting to killing the cells."

The researchers are now trying to adapt deep learning algorithms across different cell lines and biological samples. "Training deep learning models requires a large amount of data because we want to ensure that they work well in different scenarios. Fortunately, our imaging instruments make it easy for us to generate the needed training data in an efficient fashion," He said.

"These deep learning algorithms can be used for several applications," Popescu said. "We can assess the cell viability over a long time without labeling the cells, we can differentiate between different cell types in diseases, and we can study different cellular processes."