Wednesday, April 01, 2020

Uncertain climate future could disrupt energy systems

by Julie Chao, Lawrence Berkeley National Laboratory

Extreme weather events—such as severe drought, storms, and heat waves—have been forecast to become more commonplace and are already starting to occur. What has been less studied is the impact on energy systems and how communities can avoid costly disruptions, such as partial or total blackouts.

Now an international team of scientists has published a new study proposing an optimization methodology for designing climate-resilient energy systems and to help ensure that communities will be able to meet future energy needs given weather and climate variability. Their findings were recently published in Nature Energy.

"On one side is energy demand—there are different types of building needs, such as heating, cooling, and lighting. Because of long-term climate change and short-term extreme weather events, the outdoor environment changes, which leads to changes in building energy demand," said Tianzhen Hong, a Berkeley Lab scientist who helped design the study. "On the other side, climate can also influence energy supply, such as power generation from hydro, solar and wind turbines. Those could also change because of weather conditions."

Working with collaborators from Switzerland, Sweden, and Australia, and led by a scientist at the Ecole Polytechnique Fédérale de Lausanne (EPFL), the team developed a stochastic-robust optimization method to quantify impacts and then use the data to design climate-resilient energy systems. Stochastic optimization methods are often used when variables are random or uncertain.

"Energy systems are built to operate for 30 or more years. Current practice is just to assume typical weather conditions today; urban planners and designers don't commonly factor in future uncertainties," said Hong, a computational scientist leading multi-scale energy modeling and simulation at Berkeley Lab. "There is a lot of uncertainty around future climate and weather."

"Energy systems," as defined in the study, provide energy needs, and sometimes energy storage, to a group of buildings. The energy supplied could include gas or electricity from conventional or renewable sources. Such community energy systems are not as common in the U.S. but may be found on some university campuses or in business parks.

The researchers investigated a wide range of scenarios for 30 Swedish cities. They found that under some scenarios the energy systems in some cities would not be able to generate enough energy. Notably, climate variability could create a 34% gap between total energy generation and demand and a 16% drop in power supply reliability—a situation that could lead to blackouts.

"We observed that current energy systems are designed in a way that makes them highly susceptible to extreme weather events such as storms and heat waves," said Dasun Perera, a scientist at EPFL's Solar Energy and Building Physics Laboratory and lead author of the study. "We also found that climate and weather variability will result in significant fluctuations in renewable power being fed into electric grids as well as energy demand. This will make it difficult to match the energy demand and power generation. Dealing with the effects of climate change is going to prove harder than we previously thought."

The authors note that 3.5 billion people live in urban areas, consuming two-thirds of global energy, and by 2050 urban areas are expected to hold more than two-thirds of the world's population. "Distributed energy systems that support the integration of renewable energy technologies will support the energy transition in the urban context and play a vital role in climate change adaptation and mitigation," they wrote.

Hong leads an urban science research group at Berkeley Lab that studies energy and environmental issues at the city scale. The group is part of Berkeley Lab's Building Technology and Urban Systems Division, which for decades has been at the forefront of research into advancing energy efficiency in the built environment.

Extreme weather to overload urban power grids, study shows

More information: A. T. D. Perera et al, Quantifying the impacts of climate change and extreme climate events on energy systems, Nature Energy (2020). DOI: 10.1038/s41560-020-0558-0

Coronavirus having little impact on climate: UN agency

*The coronavirus crisis has cleared the streets—and the air—in cities like New Delhi, but the UN warns the change is only temporary*

Though factories have shut, planes have been grounded and cars left in the garage, the coronavirus pandemic is having very little impact on climate change, the World Meteorological Organization said Wednesday.

Any reductions in pollution and carbon dioxide emissions are likely to be temporary, said Lars Peter Riishojgaard, from the infrastructure department of the WMO, a United Nations agency based in Geneva.

"It does not mean much for climate," he told a virtual press conference.

Riishojgaard said there was a lot of media speculation about what impact the global pandemic might have on the climate, greenhouse gas emissions and longer-term global warming.

"The answer to that is it probably does not mean very much," he said.

While in the short term, carbon dioxide emissions would go down as cars stay put and aircraft remain on the ground, "we expect the impact will be fairly short-lived," Riishojgaard said.

"The pandemic will be over at some point and the world will start going back to work and with that, the CO2 emissions will pick up again, maybe or maybe not to quite the same level."

He said visibility in cities such as New Delhi had improved because there were fewer traffic-emitting fumes, but cautioned that it was only down to an "artificial halt" to normal activity.

"You could see it as maybe science experiment: what happens if all of a sudden we turn the whole thing off?" said Riishojgaard.

"It will lead some people, and perhaps also some governments, to rethink."

He reflected on China shutting down much industrial production during the Beijing 2008 Olympics.

"They demonstrated very clearly that you can absolutely, if you have enough control over the situation, you can turn off the air pollution," he said.

"But I don't think we should claim victory here yet because things will pick up again eventually."COVID-19: Economic slowdown doesn't stop climate change

Elephant welfare can be assessed using two indicators

by University of Turku

Across the world, animals are kept in captivity for various reasons: in zoos for education and research, in research facilities for testing, on farms for meat and other products, and in people's homes as pets. Maintaining good animal welfare is not only important for ethical reasons; poor welfare can impact human wellbeing and the economy. But how do we assess how animals are feeling?

One way to assess animal wellbeing is to look at stress levels. Vets typically use two biological measures of stress: stress hormone levels and white blood cell ratios. In mammals—including humans—the most important stress hormone is cortisol. When animals are faced with danger, cortisol is produced to help prepare the body for a challenge. However, if high stress and cortisol are experienced constantly, they can impact an animal's health.

In addition to cortisol, scientists can also look at the ratio of two types of white blood cells, heterophils (or neutrophils) and lymphocytes. These cells play an important role in the immune system of mammals, and after animals have experienced a stressful event, their ratio is typically high.

Researchers at the University of Turku, Finland, wanted to find out if these two biological measures of stress were correlated and whether animals with high levels of cortisol also had a high heterophil to lymphocyte ratio. They measured cortisol and heterophil to lymphocyte ratios in 120 Asian elephants from a semi-captive population of working timber elephants in Myanmar. The researchers also weighed each elephant, as body weight is a good indicator of general health.

"Some previous studies have found a positive relationship between stress hormones and heterophil to lymphocyte ratios, while others have found no relationship at all. It was also unclear from previous studies whether these two measures of stress are comparable across individuals of different sex and age, as well as across the seasons. In this population, we found that elephants with higher levels of the stress hormone cortisol also had higher ratios of heterophils to lymphocytes. This was true regardless of sex and age," says Postdoctoral Researcher and the lead author on the first study, Martin Seltmann, from the Department of Biology at the University of Turku.

An additional aim of the study was to test if stress hormones and heterophil to lymphocyte ratios are related to body weight in Asian elephants.

"We did not find a link between the white blood cell ratios and body weight, but elephants with higher levels of stress hormone had a lower body weight, indicating that elevated stress is linked to weight loss. It is useful to see that both a biological marker (cortisol) and physical indicator (body weight) of welfare respond in the same way. This means that both markers can be used to assess the wellbeing of elephants," says researcher Susanna Ukonaho, who participated in the study.

Non-experts Can Identify Stress Behaviour

In the second study, the researchers investigated whether welfare can also be reliably assessed by observing an animal's behaviour. While elephant specialists may be able to quickly identify behavioural changes, expert knowledge is not always available, so the researchers wanted to test the reliability of behavioural assessments by non-experts. First, they filmed over 100 working Asian elephants undertaking tasks that were either familiar or new to them.

"The elephants were asked to pick up different types of objects, including objects they had never seen before. This included items such as a plastic bottle, which some elephants were clearly unsure about," says the lead author on the study, Jonathan Webb.

The researchers constructed a list of elephant behaviours, which was then used by three volunteers with no prior experience of Asian elephants to collect behavioural data from the films.

To assess the reliability of the behavioural data, the researchers looked at how similar the observers' scores were for each film. They also assessed observer consistency by getting the volunteers to score films twice. They found that all three volunteers consistently and reliably identified many elephant behaviours, indicating that even with limited experience, people can reliably monitor elephant behaviour in a way which could improve the quality and safety of working elephant-human relationships.

Behavioural markers could therefore be a simple but useful tool for elephant welfare assessment on a larger scale, although the researchers caution that we still need to know how different behaviours are linked to biological measures of stress.

The relationship between different measures of animal welfare is often complex, but the findings of these two studies show that, at least when working with elephants, caretakers have several options for assessing the wellbeing of their animals. These options will not only facilitate the caretakers' work, but also help elephants to live better and healthier lives.

Explore further

New welfare tool to help improve the lives of elephants in human care

More information: Martin W. Seltmann et al, Faecal Glucocorticoid Metabolites and H/L Ratio Are Related Markers of Stress in Semi-Captive Asian Timber Elephants, Animals (2020). DOI: 10.3390/ani10010094

Provided by University of Turku

Models explain changes in cooking meat

by Springer

Meat is no ordinary solid. Made up of complex networks of moisture-saturated proteins, it displays some intriguing physical properties when it is cooked. Several studies in the past have attempted to recreate this behaviour in computer simulations, but because this demands so much computing power, they have only achieved simplified, one-dimensional recreations of the process, which aren't particularly accurate. In new research published in EPJ Plus, mathematicians led by Dr. Hala Nelson at James Madison University show that by modelling meat as a fluid-saturated matrix of elastic proteins, which are deformed as the fluid moves, cooking behaviours can be simulated more precisely.

The insights gathered by the team could have numerous advantages, such as improvements in the safety regulations which govern the meat we consume; optimisations of its quality and flavour; and new ways to maximise its shelf life to ensure minimal wastage. In the team's model, the cooking process heated the fluid unevenly, causing it to move around and deform the protein matrix. In turn, the movement of the fluid is itself altered by this distortion. The result demonstrates a fairly strong agreement with real observations—where moisture is partially evaporated but is also pushed inwards from the meat surface during heating, causing the middle to swell.

Nelson and colleagues based their model on fundamental principles of conservation of mass, energy and momentum. They derived equations describing how polymers will behave when mixed with molecules of liquid, then fine-tuned their model's parameters until it was as realistic as possible. They then compared the outcomes of their simulations with experimental measurements of how thin steak slices shrink when cooked in the oven. In future studies, the team hopes to extend their simulations to 3-D models. This would require far more computing power, but if achieved, could raise our level of understanding about the important food source.

New insights into juicy steak

More information: H. Nelson et al, A mathematical model for meat cooking, The European Physical Journal Plus (2020). DOI: 10.1140/epjp/s13360-020-00311-0

Possible lives for food waste from restaurants

by University of Córdoba

More than a third of the food produced ends up being wasted. This situation creates environmental, ethical and financial issues, that also affect food security. Negative effects from waste management, such as bad smells or the emission of greenhouse gases, make the bioeconomy one of the best options to reduce these problems.

Research into the field of the bioeconomy and the search for waste valorization strategies, such as agricultural by-products, is the field of research for the BIOSAHE (a Spanish acronym of biofuels and energy-saving systems) research group at the University of Cordoba. Led by Professor Pilar Dorado, they are now taking a step further: they aim to establish the best valorization paths for restaurant food waste. Among the possible lives for restaurant scraps, they are looking to find which one is most effective and which provides the most value.

Along these lines, researcher Miguel Carmona and the rest of the BIOSAHE group, including Javier Sáez, Sara Pinzi, Pilar Dorado and Isabel López García, developed a methodology that assesses food waste and selects the best valorization path.

After analyzing food waste from a variety of different kinds of restaurants with varying degrees of caliber, the main chemical components were characterized, those being starches, proteins, lipids and fibers. The aim of this process was to find out what amounts of what compounds are held in food waste in order to link it to the best option for its transformation.

Once the chemical compounds of the scraps were identified, a statistical study was performed to analyze the variability (how compounds vary and the amounts of some waste compared to other waste).

Identifying compound typology and variability makes it possible to predict the most optimal valorization process depending on the waste, thus helping industries within the circular economy and the resource valorization sector to make decisions.

In this way, the lives of restaurant scraps can be turned into biodiesel, electricity or bioplastic. Specifically, the project that Pilar Dorado heads is developing a biorefinery that would, just as oil refineries do, generate biofuel, bioplastic, biolubricants and products with added value in the chemical, electrical and heat industries from restaurant food waste. In this project, in addition to the methodology that characterizes scraps and chooses the best paths, they have produced bioplastic that can be used as sutures in surgery procedures.

Turning food waste into bioplastics

More information: M. Carmona-Cabello et al, Food waste from restaurant sector – Characterization for biorefinery approach, Bioresource Technology (2020). DOI: 10.1016/j.biortech.2020.122779

Journal information: Bioresource Technology

First complete German shepherd DNA offers new tool to fight disease

by University of New South Wales

Scientists have mapped the genome of the German shepherd, one of the world's most popular canine breeds, after using a blood sample from 'Nala,' a healthy five-year-old German shepherd living in Sydney.

In a paper published today in respected 'big data' journal GigaScience, a global team of researchers from institutions including UNSW Sydney detailed the mammoth task of unravelling the 38 pairs of dog chromosomes to decode the 19,000 genes and 2.8 billion base pairs of DNA, using advanced genetic sequencing technology.

The new genome not only provides science with a more complete biological snapshot of the dog species (Canis lupus familiaris) in general, but also offers a reference for future studies of the typical diseases that afflict this much-loved breed.

Popular choice

UNSW Science's Professor Bill Ballard, an evolutionary biologist who sequenced the genome of the Australian dingo in 2017, says German shepherds are popular choices in the home and the workplace because of their natural intelligence, balanced temperament and protective nature. But after more than a century of breeding for desired physical characteristics, they are particularly vulnerable to genetic diseases.

"One of the most common health problems affecting German shepherds is canine hip dysplasia, which is a painful condition that can restrict their mobility," says Professor Ballard.

"Because German shepherds make such good working dogs, there has been a lot of money spent looking into the causes and predictors of this problem. When working dogs—such as those trained to work with police or to help people with disabilities—end up getting hip dysplasia, then that's a lot of lost time and money that has gone into the training of that dog.

"Now that we have the genome, we can determine much earlier in life whether the dog is likely to develop the condition. And over time, it will enable us to develop a breeding program to reduce hip dysplasia in future generations."

Top dog

Nala, who was described in the paper as "an easy going and approachable 5.5 year old," was selected because she was free of all known genetic diseases, including no sign of hip dysplasia. She was located by well-known TV and radio vet Dr. Robert Zammit—credited as an author of this paper—who Professor Ballard says has amassed X-rays and blood samples of more than 600 German shepherds.

"Now we'll be able to look at those hip x-rays and all the DNA of those dogs and compare them back to this healthy reference female," Professor Ballard says.

Nala isn't the first domestic dog to provide a sample for the mapping of the dog genome. In 2003 a poodle called Shadow provided a sample that resulted in a genome that was 80 per cent complete, followed two years later by the first complete mapping of the genome of 'Tasha' the Boxer.

Gene machines

But in the decade and a half since, technology has vastly improved to the point that the number of gaps—or regions of DNA bases that are unreadable—has fallen dramatically, making the mapping of Nala's genes the most complete yet.

"The biggest difference between the mapping today and in 2005 is that we now use long read sequencing," says Professor Ballard.

"The Boxer's genome was put together with 'Sanger' sequencing, which can read about 1000 bases in length at a time, while the technology that is available today—Next Generation sequencing—can read up to 15,000 bases.

"What this means is if you've got a region of genes that is duplicated and running more than 1000 bases, Sanger sequencing will not be able to tell you which part of the genes that particular sequence comes from. So whereas there were about 23,000 gaps in Sanger's Boxer genome, the Next Gen sequencer had just over 300."

Bred for success

The German shepherd genome is also an advance on 2005's Boxer genome because of the breed itself. As Boxers are more specialised, with more inbreeding in their genetic history, the German shepherd's genome is therefore more generic. The authors believe that this will provide better understanding of the evolution of dog breeds in general.

Professor Ballard reckons this will not be the last time a domestic dog breed's genome is sequenced.

"I would expect that as the costs come down, all the major breeds will have a genome mapped within 10 years, because this will help identify specific diseases, and lots of breeds have known specific diseases."

More genes associated with canine hip dysplasia and osteoarthritis discovered

More information: Matt A Field et al. Canfam_GSD: De novo chromosome-length genome assembly of the German Shepherd Dog (Canis lupus familiaris) using a combination of long reads, optical mapping, and Hi-C, GigaScience (2020). DOI: 10.1093/gigascience/giaa027

Journal information: GigaScience

Vermont has conserved one third of the land needed for an ecologically functional future

by University of Vermont

For the first time in more than a century, Vermont and neighboring states are losing forestland to development at a rate of almost 1,500 acres per year. As forest fragmentation gains ground across the New England landscape, where private ownerships and small land parcels are the norm, conserving land for future generations of people, wildlife, and plants becomes more necessary but more difficult.

Vermont is a third of the way there. In a new study, forest conservation experts at the University of Vermont (UVM) confirmed that the state has already protected 33%, or 1.3 million acres, of highest priority targeted lands needed to protect and connect valuable wildlife habitats and corridors.

Most of the currently conserved lands are forested, yet not nearly enough of the state's highest priority targeted surface water and riparian areas—ponds, rivers, shorelines, and wetlands—are protected. Many animals require zones along waterways in which to travel between habitats they need to survive.

The researchers scrutinized Vermont's new state-level vision for conservation, Vermont Conservation Design, meant to create physical pathways for movement of animals and plants across the landscape, especially in a future of changing climate. They compiled a database of Vermont's conserved lands and overlaid them with the state's highest priority landscape targets.

"The State of Vermont and a number of partners have laid out an impressive, thoughtful vision to ensure that Vermont remains a good place for all forms of life in the future," said Carolyn Loeb, a graduate student in the UVM College of Agriculture and Life Sciences' Field Naturalist Program who led the study. "Our goal was to answer the questions: how far have we come, what successes and gaps do we see so far in fulfilling the design, and where do we go from here?"

The study, "Large landscape conservation in a mixed ownership region: Opportunities and barriers for putting the pieces together," was published in the journal Biological Conservation in March 2020 with free online access until April 18, 2020.

Of Vermont's protected land, the authors found that 87% of those acres, or 22% of the state's total land base, are also considered highest priority by Vermont Conservation Design targets.

"Our research indicates that past conservation efforts in Vermont really matter, even though our reasons and perspectives around conservation have evolved," said Loeb.

Historically, forest conservation targeted high elevation settings—think summit of Vermont's Camel's Hump. The study found that the state has adequately conserved higher elevation lands that are also design targets, but lower elevation targets remain a gap among protected areas.

"Vermont is at a critical juncture in conserving the wild and working forest landscapes of the state, as we observe losses in forest cover to development and other land uses," said Tony D'Amato, a professor in the UVM Rubenstein School of Environment and Natural Resources. "This study provides a crucial benchmark of current levels of forest protection to help prioritize future conservation actions to achieve the impressive vision Vermont Conservation Design has outlined for sustaining the ecological, economic, and social benefits of Vermont's forests into the future."

Across all 1.5 million acres of Vermont's currently conserved lands, three groups dominate in responsibility for the most protected lands: the national government, the state, and private nonprofit organizations, which can also conserve lands on behalf of other private landowners.

The public sector of national and state government each hold responsibility for 30.5% of protected lands, which include the U.S. Forest Service's Green Mountain National Forest, other federal lands, and the Vermont state parks, forests, and wildlife management areas. The Vermont Department of Forests, Parks and Recreation protects the most design-targeted lands of any state agency.

Nonprofit organizations have responsibility for 35.4% of protected lands, while town and tribal entities hold responsibility for 3.6% and 0.01% of conserved lands, respectively.

While public agencies are responsible for most of the highest priority forested area targets in Vermont, nonprofit organizations have protected the largest percentage of highest priority riparian and surface water targets. Nonprofits, such as the Vermont Land Trust and The Nature Conservancy in Vermont, through conservation easements, have played a unique role in protecting these wetlands and waterways. But the study underscores that there are still notable gaps in protecting low elevation and riparian lands identified in the design as very important.

"Going forward, Vermont's nonprofits will play an increasingly important role in land conservation, especially in continuing to protect those areas that are rich with species diversity," said Elizabeth Thompson, Director of Conservation Science at Vermont Land Trust. "Nonprofits are engaging more and more deeply in restoring wetlands that were previously degraded, planting new forests along river shores to slow flood waters and provide wildlife habitat, and protecting unique natural communities while also protecting working forests and farmland."

The authors recommend continued support for collaboration between public and private partners in land conservation, planning for quick response to large and potentially unexpected land sales that are important design targets, increased assistance for nonprofits in gaining protections for under-represented surface waters and connected riparian area targets, and a greater focus on protection of low-elevation targeted lands in Vermont by turning to strategies for better connecting the small ownership, patchworked landscapes that occur in much of the stateIdentifying forests for protection in Borneo

More information: Carolyn D. Loeb et al, Large landscape conservation in a mixed ownership region: Opportunities and barriers for putting the pieces together, Biological Conservation (2020). DOI: 10.1016/j.biocon.2020.108462

FDA wants heartburn meds off the market due to contamination

by Matthew Perrone

The move from the Food and Drug Administration Wednesday applies to all prescription and over-the-counter versions of ranitidine, best known by the brand name Zantac. The drugs are widely used to treat stomach acid and ulcers.

Patients should stop taking any of the medications they currently have and throw them away, the FDA said.

The agency last year said patients could continue taking the medications and did not face health risks from low levels of a "probable" cancer-causing contaminant found in multiple brands.

But officials reversed that decision, saying they've now determined that levels of the chemical increase over time, especially if tablets and capsules are stored at higher temperatures. That poses an unacceptable risk to patients, they said.

"Since we don't know how or for how long the product might have been stored, we decided that it should not be available to consumers and patients," said Dr. Janet Woodcock in a statement.

Woodcock said there are multiple alternative medications to treat heartburn, including Prilosec, Nexium and Tagament.

Many makers of ranitidine drugs already removed their products from the market, including Zantac-manufacturer Sanofi. Additionally several drug store chains pulled the drugs from their shelves last year.

Dozens of recalls have been linked to the same probable carcinogen since last year. The FDA is still investigating the issue and has sanctioned at least one manufacturing plant in India that makes ingredients used in the medications.

The FDA has suspended nearly all U.S. and foreign inspections due to travel restrictions caused by the coronavirus outbreak.

CVS stops sale of heartburn drugs with suspect contaminant

'A battlefield behind your home': Deaths mount in New York

by Robert Bumsted, Angela Charlton and Mark Sherman

A funeral director and a Wycoff Heights Medical Center, employee transport a body, Wednesday, April 1, 2020, in New York. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially older adults and people with existing health problems, it can cause more severe illness or death. (AP Photo/Mary Altaffer)

New York authorities rushed to bring in an army of medical volunteers Wednesday as the statewide death toll from the coronavirus doubled in 72 hours to more than 1,900 and the wail of ambulances in the otherwise eerily quiet streets of the city became the heartbreaking soundtrack of the crisis.

As hot spots flared around the U.S. in places like New Orleans, Detroit and Southern California, the nation's biggest city was the hardest hit of them all, accounting for most of the state's dead, with bodies loaded onto refrigerated morgue trucks by gurney and forklift outside overwhelmed hospitals, in full view of passing motorists.

And the worst is yet to come.

"How does it end? And people want answers," New York Gov. Andrew Cuomo said. "I want answers. The answer is nobody knows for sure."

Across the U.S., Americans braced for what President Donald Trump warned on Tuesday could be "one of the roughest two or three weeks we've ever had in our country." The White House projected 100,000 to 240,000 deaths in the U.S. before the crisis is over, and Vice President Mike Pence said models for the outbreak show the country on a trajectory akin to hard-hit Italy's.

Under growing pressure, Florida Gov. Ron DeSantis belatedly joined Cuomo and governors in more than 30 states in issuing a statewide stay-home order, taking action after conferring with fellow Republican Trump. The governors of Pennsylvania and Nevada, both Democrats, took similar steps. Mississippi's GOP was expected to follow suit.

A woman, wearing a protective face mask as a precaution against the new coronavirus, rides in a public cable car in Bogota, Colombia, Wednesday, April 1, 2020. Health authorities have begun checking the temperature of commuters as a measure to contain the spread of COVID-19. (AP Photo/Fernando Vergara)

Meanwhile, European nations facing extraordinary demand for intensive-care beds are putting up makeshift hospitals, unsure whether they will find enough healthy medical staff to run them. London is days away from unveiling a 4,000-bed temporary hospital built in a huge convention center.

In a remarkable turnabout, rich economies where virus cases have exploded are welcoming help from less wealthy ones. Russia sent medical equipment and masks to the United States. Cuba supplied doctors to France. Turkey dispatched protective gear and disinfectant to Italy and Spain.

Worldwide, more than 900,000 people have been infected and over 45,000 have died, according to a tally kept by Johns Hopkins University, though the real figures are believed to be much higher because of testing shortages, differences in counting the dead and large numbers of mild cases that have gone unreported.

A patient is taken from an ambulance outside St Thomas Hospital in London, Wednesday, April 1, 2020, the hospital is one of many treating Coronavirus patients. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially older adults and people with existing health problems, it can cause more severe illness or death.(AP Photo/Alberto Pezzali)

The U.S. recorded about 200,000 infections and about 4,400 deaths, with New York City accounting for about 1 out of 4 dead.

In New York, more than 80,000 people have volunteered as medical reinforcements, including recent retirees, health care professionals taking a break from their regular jobs and people between gigs.

Few have made it into the field yet, as authorities vet them and figure out how to use them, but hospitals are expected to begin bringing them in later this week.

Those who have hit the ground already, many brought in by staffing agencies, have discovered a hospital system being driven to the breaking point.

"It's hard when you lose patients. It's hard when you have to tell the family members: 'I'm sorry, but we did everything that we could,'" said nurse Katherine Ramos, of Cape Coral, Florida, who has been working at New York Presbyterian Hospital. "It's even harder when we really don't have the time to mourn, the time to talk about this."

Medical staff of a mobile unit take samples to test for Covid-19, at the Santa Maria della Pieta' hospital complex, in Rome, Wednesday, April 1, 2020. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially older adults and people with existing health problems, it can cause more severe illness or death. (Cecilia Fabiano/LaPresse via AP)

To ease the crushing caseload, the city's paramedics have been told they shouldn't take fatal heart attack victims to hospitals to have them pronounced dead. Patients have been transferred to the Albany area. A Navy hospital ship has docked in New York, the mammoth Javits Convention Center has been turned into a hospital, and the tennis center that hosts the U.S. Open is being converted to one, too.

With New York on near-lockdown, the normally bustling streets in the city of 8.6 million are empty, and a siren to some is no longer just urban background noise. Cuomo moved to close the city's playgrounds because of too much crowding, but people can still use wide-open green spaces as long as they stay 6 feet apart. Police went around in patrol cars, blaring warnings to obey the rules.

"After 9/11, I remember we actually wanted to hear the sound of ambulances on our quiet streets because that meant there were survivors, but we didn't hear those sounds, and it was heartbreaking. Today, I hear an ambulance on my strangely quiet street and my heart breaks, too," said 61-year-old Meg Gifford, a former Wall Streeter who lives on Manhattan's Upper East Side.

A worker sprays disinfectant to sanitize Duomo square, as the city main landmark, the gothic cathedral, stands out in background, in Milan, Italy, Tuesday, March 31, 2020. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially older adults and people with existing health problems, it can cause more severe illness or death. (AP Photo/Luca Bruno)

Near severely swamped Elmhurst Hospital in Queens, resident Emma Sorza, 33, described an eerie scene.

"I think everyone's just doing what they can, but at the same time it bothers you. Especially if you're around Elmhurst, because you can hear all the ambulances, she said. "There is a truck and people are actually dying. It's like a battlefield behind your home."

Cuomo said projections suggest the crisis in New York will peak at the end of April, with a high death rate continuing through July.

"Let's cooperate to address that in New York because it's going to be in your town tomorrow," he warned. "If we learn how to do it right here—or learn how to do it the best we can, because there is no right, it's only the best we can—then we can work cooperatively all across this country."

Elsewhere around the country, Florida's DeSantis was locked in a standoff over whether two cruise ships with sick and dead passengers may dock in his state. More than 300 U.S. citizens were on board. Two deaths were blamed on the virus, and nine people tested positive, Holland America cruise line said.

A man wears a face mask as he walks past murals of wildlife outside of a subway station in Beijing, Wednesday, April 1, 2020. China's National Health Commission on Wednesday reported a few dozens of new COVID-19 cases, one day after announcing that asymptomatic cases will now be included in the official coronavirus count. (AP Photo/Mark Schiefelbein)

DeSantis, who is close to Trump, said the state's health system is stretched too thin to accommodate the passengers. But the president said he would speak with him. "They're dying on the ship," Trump said. "I'm going to do what's right. Not only for us, but for humanity."

In Southern California, officials reported that at least 51 residents and six staff members at a nursing home east of Los Angeles have been infected and two have died.

Even as the virus has slowed its growth in overwhelmed Italy and in China, where it first emerged, hospitals on the Continent are buckling under the load.

"It feels like we are in a Third World country. We don't have enough masks, enough protective equipment, and by the end of the week we might be in need of more medication too," said Paris emergency worker Christophe Prudhomme.

Dr. Sherry Yu demonstrates a free-standing booth for COVID-19 testing, Wednesday, April 1, 2020, at Brigham & Women's Hospital in Boston. The isolation booths were created by a collaboration of the hospital's clinical leaders and engineering team, inspired by a South Korean research design. The booths separate clinicians from patients, protect front line providers, and reduce the need for personal protective equipment. (AP Photo/Elise Amendola)

Spain hit a record of 864 deaths in one day, for a total of more than 9,000, while France reported an unprecedented 509 deaths and more than 4,000 in all. In Italy, with over 13,000 dead, the most of any country, morgues overflowed with bodies, caskets piled up in churches, and doctors were forced to decide which desperately ill patients would get breathing machines.

England's Wimbledon tennis tournament was canceled for the first time since World War II.

India's highest court ordered news media and social media sites to carry the government's "official version" of developments, echoing actions taken in other countries to curb independent reporting.

The strain facing some of the world's best health care systems has been aggravated by hospital budget cuts over the past decade in Italy, Spain, France and Britain. They have called in medical students, retired doctors and even laid-off flight attendants with first aid training.

A view of the unusually empty embankment during evening rush hour outside the Kremlin in Moscow, Russia, Wednesday, April 1, 2020. The Russian capital has woken up to a lockdown obliging most people in the city of 13 million to stay home. The government ordered other regions of the vast country to quickly prepare for the same as Moscow, to stem the spread of the new coronavirus. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially older adults and people with existing health problems, it can cause more severe illness or death. (AP Photo/Pavel Golovkin)

A man wearing a mask to help stop the spread of the coronavirus passes advertising display London, Wednesday, April 1, 2020, stating "Community is Kindness'. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially older adults and people with existing health problems, it can cause more severe illness or death.(AP Photo/Kirsty Wigglesworth)

Harare City Council workers wear masks while disinfecting a bus terminal, in Harare, Zimbabwe, Wednesday, April, 1, 2020. Zimbabwe is on a lockdown for 21 days in an effort to curb the spread of the coronoavirus. (AP Photo/Tsvangirayi Mukwazhi)

A nurse in protective clothing takes notes from a woman with symptoms of new coronavirus at a carpark that turned into a COVID-19 infection screening center at Chulalongkorn University health service center in Bangkok, Thailand, Wednesday, April 1, 2020. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially older adults and people with existing health problems, it can cause more severe illness or death. (AP Photo/Gemunu Amarasinghe)

A volunteer wearing a face shield and mask manages a counter of COVID-19 infection screening center at the Chulalongkorn University health service center in Bangkok, Thailand, Wednesday, April 1, 2020. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially older adults and people with existing health problems, it can cause more severe illness or death. (AP Photo/Gemunu Amarasinghe)

A stranded Australian citizen arrives to catch a bus on his way to take a rescue flight from Tribhuvan International Airport in Kathmandu, Nepal, Wednesday, April 1, 2020. Stranded tourists from Australia and New Zealand boarded a chartered flight out of Nepal Wednesday. The Nepal Airlines flight had 222 Australians and 28 New Zealand nationals and permanent residents. (AP Photo/Niranjan Shrestha)

A worker disinfects a window in affords to stem the spread of the new coronavirus in Prague, Czech Republic, Wednesday, April 1, 2020. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially older adults and people with existing health problems, it can cause more severe illness or death. (AP Photo/Petr David Josek)

An Israeli woman wears a mask as she crosses the street in Tel Aviv, Israel, Wednesday, April 1, 2020. Israel's military has deployed hundreds of troops to assist police in enforcing health regulations meant to stem the spread of the new coronavirus. Soldiers and police are setting up roadblocks and inspecting passing cars, asking motorists for their reasons for leaving the house. (AP Photo/Sebastian Scheiner)

The staffing shortage has been exacerbated by the high numbers of infected personnel. In Italy alone, nearly 10,000 medical workers have been infected and more than 60 doctors have died.

For most people, the coronavirus causes mild or moderate symptoms, such as fever and cough. But for others, especially older adults and people with health problems, it can cause severe symptoms like pneumonia and lead to death.

China, where the outbreak began late last year, on Wednesday reported just 36 new COVID-19 cases.Follow the latest news on the coronavirus (COVID-19) outbreak

Healthy-looking people spread coronavirus, more studies say
by Mike Stobbe

In this Tuesday, March 31, 2020 file photo, neighbors line up for free food staples outside Santa Ana primary school in Asuncion, Paraguay, part of an already existing food program through the Education Ministry, as people stay home from work amid the spread of the COVID-19 coronavirus. According to research released on Wednesday, April 1, 2020, more evidence is emerging that coronavirus infections are being spread by people who have no clear symptoms, complicating efforts to gain control of the pandemic. (AP Photo/Jorge Saenz)

More evidence is emerging that coronavirus infections are being spread by people who have no clear symptoms, complicating efforts to gain control of the pandemic.

A study conducted by researchers in Singapore and published by the U.S. Centers for Disease Control and Prevention Wednesday is the latest to estimate that around 10% of new coronavirus infections may be sparked by people who were infected with the virus but not experiencing symptoms.

In response to recent studies, the CDC changed how it was defining the risk of infection for Americans. The agency's new guidance, also released Wednesday, targets people who have no symptoms but were exposed to persons with known or suspected infections. It essentially says that anyone may be a considered a carrier, whether they have symptoms or not.

That reinforces the importance of social distancing and other measures designed to stop the spread, experts said.

"You have to really be proactive about reducing contacts between people who seem perfectly healthy," said Lauren Ancel Meyers, a University of Texas at Austin researcher who has studied coronavirus transmission in different countries.

The new study focused on 243 cases of coronavirus reported in Singapore from mid-January through mid-March, including 157 among people who hadn't traveled.

Researchers found that so-called pre-symptomatic people triggered infections in seven different clusters of disease, accounting for about 6% of the locally-acquired cases.

An earlier study in Hubei province, China, where the virus was first identified, suggested that more than 10% of transmissions could have occurred before patients spreading the virus ever exhibited symptoms.

Researchers are also looking into the possibility that additional cases are triggered by "asymptomatic" people who are infected but never develop clear-cut symptoms, and "post-symptomatic" people who got sick, appear to be recovered, but may still be contagious.

It remains unclear how many new infections are caused by each type of these potential spreaders, said Meyers, who was not involved in the Singapore study but was part of an earlier one focused on China.

CDC officials say they've been researching asymptomatic and pre-symptomatic infections, but the studies are not complete.

In the initial months of the pandemic, health officials based their response on the belief that most of the spread came from people who were sneezing or coughing droplets that contained the virus.

Coronavirus spreads quickly and sometimes before people have symptoms, study finds

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