Buzz Me Baby: Unusual Courtship Songs for Valentine’s Day

 We heart the Ostrinia nubilalis

When most people think of Valentine’s Day, images of love, candy, and flowers pop to mind.  However, this Valentine’s Day, we thought we’d share two animals with you that use scales, wings, and other things to create songs that attract that special someone.

Moth Melodies

Male moths use a combination of pheromones and ultrasound—sound with frequencies above the range of human hearing—to woo females. To better understand moth sounds during courtship, researchers in this PLOS ONE study recorded and examined the ultrasounds emitted by three types of grass moths. They found that two of the three moth species had sex-specific wing and thoracic scales that played a role in ultrasound production, and that using these scales increased mating success. This audio clip is the recorded ultrasound of Ostrinia nubilalis (pictured above), aka the European corn borer, slowed down 10 times so that human ears can hear it.

CotesiaWasp Chorus

Cotesia Wasp

Rapid wing fanning is the attraction tool of choice for male wasps when courting females. According to this PLOS ONE study, parasitic wasp wing fanning has been studied before, but the mechanism for how the sound is generated has not.  The researchers characterized the wasp songs and found that they contain a two-part signal with sequences of buzzes and boing sounds. While scientists could characterize  the male courtship songs, how they produce the sound remains a mystery. This audio clip starts with wing fanning, which produces a buzz sound, and is followed by a series of boing sounds.

 


Whether you choose to scale, buzz, or boing to impress your mate with beautiful music, we wish you a Happy Valentine’s Day from PLOS ONE!

 

Citations: 

Takanashi T, Nakano R, Surlykke A, Tatsuta H, Tabata J, et al. (2010) Variation in Courtship Ultrasounds of Three Ostrinia Moths with Different Sex Pheromones. PLoS ONE 5(10): e13144. doi:10.1371/journal.pone.0013144

Bredlau JP, Mohajer YJ, Cameron TM, Kester KM, Fine ML (2013) Characterization and Generation of Male Courtship Song in Cotesia congregata(Hymenoptera: Braconidae). PLoS ONE 8(4): e62051. doi:10.1371/journal.pone.0062051

Image Credits:

Photo a Ostrinia nubilalis by dhobern. Heart added by us.

Dorsal view of one pair of wings of a male Cotesia congregata. Figure 8. doi:10.1371/journal.pone.0062051.g008

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It’s Not Easy Being Green: Assessing the Challenges of Urban Community Gardening

urbangardenSF

From vertical gardens to succulent gardens to community veggie gardens like the San Francisco garden pictured above, city dwellers all around us have started embracing their (hopefully) green thumbs.  For urbanites in particular, community gardening provides us with much needed “outside time” with likeminded individuals, with the added gift of hyper-local produce available throughout the growing season. These benefits have led to increases in residential and community garden participation in major cities across the US.

While many people are jumping on the garden-fresh bandwagon to reap the obvious, verdant benefits, it is important to consider the potential side effects that come alongside urban farming. Urban soil is not only closer to possible sources of pollution, like traffic and industrial areas, but could also contain residual chemicals from past land use. Residential land previously occupied by industrial buildings has been found to contain dangerous levels of toxins like lead, which can poison residents and contaminate food grown on-site. But it doesn’t take a former factory to contaminate your backyard. Soil can absorb and hold toxins left over from something as small as a previous homeowners dumping of cleaning water down the drain or off the back porch.

Researchers from Baltimore published an article in PLOS ONE earlier this month assessing Baltimore community gardeners’ knowledge of soil contamination risks and explored what steps can be taken to mitigate the dangers of urban pollution in urban gardens.

The authors, hailing from Johns Hopkins, University of Maryland, and the Community Greening Resource Network, conducted interviews with Baltimore’s community garden members, and found that unfortunately, the gardeners generally seem to have low levels of concern about potential contaminants in their soil. Those working in established community gardens were least concerned as they often assumed that any issues with soil contamination had been addressed in the early days of the garden’s use.

When participants were asked what soil contaminants they are aware of, lead was the most common response—likely due to city interventions concerning lead poisoning—with 66% of surveyed gardeners mentioning it in their interviews. The study results also indicate that gardeners are more worried about the presence of pesticides and other added chemicals than most other residual chemicals in the soil. Soil quality and fertility even took greater precedence for some gardeners than the presence of contaminants.

By interviewing Baltimore officials knowledgeable about community gardening practices and soil contamination issues, the researchers determined key steps in assuring the safety of gardening sites. Above all, officials suggested the creation of a central source of information related to soil contamination concerns. Similar projects relating to regulation and urban agriculture are already underway in places like Los Angeles, though these resources aim to help residents navigate the maze of confusing legislation related to urban agriculture, and focus less on providing information on how to evaluate the safety of specific plots of land.

The authors suggest other important ways to determine the safety of a garden site, including learning about the site’s past uses and testing the soil for lingering chemicals, both of which might not seem necessary to those untrained in urban planning or chemical analysis. They also recommend that officials in urban areas provide services that will encourage use of these tools and help gardeners find and interpret the results of soil testing or historical research.

In the meantime, the authors suggest limiting exposure to potentially contaminated land. For instance, we should minimize contact with dirt from garden sites by washing our hands and taking off shoes before entering any indoor spaces. Many interviewed gardeners have tried to mitigate this problem by using raised beds, which they believe eliminates concern about contaminants in homegrown vegetables. However, researchers have found limitations with this method, and it should not be seen as a fix-all. Raised beds do not prevent contamination from soil around the beds, which can still be ingested or tracked into the home, and surrounding pollutants have been known to blow into beds or seep into the soil from treated wood used to build the structures.

Urban community gardening is a trend that is here to stay, and we have it to thank for fresher local produce, greener surroundings, a greater sense of community, and for the physical, and sometimes therapeutic, activity it provides. The potential dangers associated with gardening in urban areas probably do not outweigh the benefits, as long as gardeners remain diligent and become better informed. Though their study focused on a limited group, this paper’s findings draw attention to the fact that they’re not. So, next time you’re digging into a grassy patch in your backyard with visions of veggies or working in your local community garden, take a minute to think about what you know about your area, discuss past developments with longtime residents, and above all, clean up afterward.

More information on soil testing and good gardening practices can be found on this site from the EPA.

UPDATE: This post has been updated to clarify that the statistics on gardener awareness of soil contaminants measured only awareness, and not concern for the soil they work with. It was also changed to clarify that raised beds do provide some protection against soil contamination from the surrounding area, though they have limitations.

Citation: Kim BF, Poulsen MN, Margulies JD, Dix KL, Palmer AM, et al. (2014) Urban Community Gardeners’ Knowledge and Perceptions of Soil Contaminant Risks. PLoS ONE 9(2): e87913. doi:10.1371/journal.pone.0087913

Image: Tenderloin People’s Garden by SPUR

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Two Shark Studies Reveal the Old and Slow

Sharks live in the vast, deep, and dark ocean, and studying these large fish in this environment can be difficult. We may have sharks ‘tweeting’ their location, but we still know relatively little about them. Sharks have been on the planet for over 400 million years and today, there are over 400 species of sharks, but how long do they live, and how do they move? Two recent studies published in in PLOS ONE have addressed some of these basic questions for two very different species of sharks:  great whites and megamouths.

The authors of the first study looked at the lifespan of the great white shark. Normally, a shark’s age is estimated by counting growth bands in their vertebrae (image 1), not unlike counting rings inside a tree trunk. But unfortunately, these bands can be difficult to Great white vertdifferentiate in great whites, so the researchers dated the radiocarbon that they found in them. You might wonder where this carbon-14 (14C) came from, but believe it or not, radiocarbon was deposited in their vertebrae when thermonuclear bombs were detonated in the northwestern Atlantic Ocean during the ‘50s and ’60s. These bands therefore provide age information. Based on the ages of the sharks in the study, the researchers suggest that great whites may live much longer than previously thought. Some male great whites may even live to be over 70 years old, and this may qualify them as one of the longest-living shark species. While these new estimates are impressive, they may also help scientists understand how threats to these long-living sharks may impact the shark population.

A second shark study analyzed the structure of a megamouth shark’s pectoral fin (image 2) to understand and predict their motion through the water. Discovered megamouth finin 1976, the megamouth is one of the rarest sharks in the world, and little is known about how they move through the water. We do know that the megamouth lives deep in the ocean and is a filter feeder, moving at very slow speeds to filter out a meal with its large mouth. But swimming slowly in the water is difficult in a similar way flying slowly in an airplane is difficult. Sharks need speed to control lift and movement.

To better understand the megamouth’s slow movement, the researchers measured the cartilage, skin histology, and skeletal structure of the pectoral fins of one female and one male megamouth shark, caught accidentally and preserved for research. The researchers found that the megamouth’s skin was highly elastic, and its cartilage was made of more ‘segments’ than any other known shark, which may provide added flexibility compared to other species. megamouth jointThe authors also suggest that the joint structure (image 3) of the pectoral fin may allow forward and backward rotation, motions that are largely restricted in most sharks.  The authors suggest that this flexibility and mobility of the pectoral fin may be specialized for controlling body posture and depth at slow swimming speeds. This is in contrast to the fins of fast-swimming sharks that are generally stiff and immobile.

In addition to the difficulties in exploring deep, dark seas, small sample sizes present challenges for many shark studies, including those described here. But whether studying the infamous great white shark or one of the rare megamouths, both contribute to a growing body of knowledge of these elusive fish.

Citations: Hamady LL, Natanson LJ, Skomal GB, Thorrold SR (2014) Vertebral Bomb Radiocarbon Suggests Extreme Longevity in White Sharks. PLoS ONE 9(1): e84006. doi:10.1371/journal.pone.0084006

Tomita T, Tanaka S, Sato K, Nakaya K (2014) Pectoral Fin of the Megamouth Shark: Skeletal and Muscular Systems, Skin Histology, and Functional Morphology. PLoS ONE 9(1): e86205. doi:10.1371/journal.pone.0086205

Images1: doi:10.1371/journal.pone.0084006.g001

Image 2: doi:10.1371/journal.pone.0086205.g003

Image 3: doi:10.1371/journal.pone.0086205.g004

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All Dried Up? Modeling the Effects of Climate Change in California’s River Basins

Mono Lake
Whether you are trapped inside because of it, or mourning the lack of it, water is on everyone’s mind right now. Too much snow in the Midwest and Northeast has been ruining travel plans, while too little snow is limiting Californians’ annual ski trips. No one wants to drive three hours only to find a rocky hillside where their favorite slope used to be.

It’s hard to deny that abnormal things are happening with the weather right now. Recently, Governor Jerry Brown officially declared a state of emergency in California due to the drought and suggested that citizens cut water usage by 20%. With no relief in sight, it is important not only to regulate our current water use, but also to reevaluate our local programs and policies that will affect water usage in the future. So, how do we go about making these decisions without being able to predict what’s next? A recently published PLOS ONE article may offer an answer in the form of a model that allows us to estimate how potential future climate scenarios could affect our water supply.

journal.pone.0084946.g001

Researchers from UC Berkeley and the Stockholm Environmental Institute’s (SEI) office in Davis, CA built a hydrology simulation model of the Tuolumne and Merced River basins, both located in California’s Central Valley (pictured above). Their focus was on modeling the sensitivity of California’s water supply to possible increases in temperature. When building the model, the authors chose to incorporate historical water data, current water use regulations, and geographical information to estimate seasonal water availability across the Central Valley and the San Francisco Bay Area. They then ran various water availability scenarios through the model to predict how the region could be affected by rising temperatures.

Using estimated temperature increases of 2°C, 4°C, and 6°C, the model predicted earlier snowmelts, leading to a peak water flow earlier in the year than in previous years. The model also forecasted a decreased river flow due to increased evapotranspiration (temperature, humidity, and wind speed). The water supply was also estimated to drop incrementally with each temperature increase, though it is somewhat cushioned by the availability of water stored in California’s reservoirs.

journal.pone.0084946.g002

The authors used an existing model as an initial structure, and built upon it to include information on local land surface characteristics, evapotranspiration, precipitation, and runoff potential. Surrounding water districts were modeled as nodes and assigned a priority according to California’s established infrastructure and legislation. Using this information, the authors state that the tool is equipped to estimate monthly water allocation to agricultural and urban areas and compare it to historical averages for the same areas.

Though a broad model, the authors present it as a case study that provides estimates of longer-term water availability for the Central Valley and Bay Area, and encourage other areas to modify its design to meet the needs of their unique locales. Those of us looking for more specific predictions can also use the tool to create models with additional information and refined approximations, allowing flexibility for future changes in land use and policy. For now, we might have a good long-term view of our changing water supply and a vital tool as we race to keep up with our ever-changing world.

Citation: Kiparsky M, Joyce B, Purkey D, Young C (2014) Potential Impacts of Climate Warming on Water Supply Reliability in the Tuolumne and Merced River Basins, California. PLoS ONE 9(1): e84946. doi:10.1371/journal.pone.0084946

Image 1 Credit: Mono Lake by Stuart Rankin

Image 2 Credit: Figure 1 pone.0084946

Image 3 Credit: Figure 2 pone.0084946

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The Missing Underwater Forests of Australia: Restoring Phyllospora comosa Around Sydney

restoration_Adriana Verges

Although seaweed is the dominant habitat-forming organism along temperate coastlines, one of the major macroalgae of Australia, Phyllospora comosa, has disappeared over the last forty years from the urban shores around Sydney, Australia. Human activity is likely related to the degradation of these habitats in urbanized areas: During the 1970s and 1980s, humans discharged large amounts of sewage from nearby cities along surrounding coasts. Unfortunately, despite significant improvements in water quality around Sydney since, Phyllospora has not returned. To test whether Phyllospora can ever be restored in reefs where it was once abundant, authors of a recent PLOS ONE paper transplanted Phyllospora into two reefs in the Sydney area. In this interview, corresponding author Dr. Alexandra Campbell from the University of New South Wales elaborates on the group’s research and the impact of these ‘missing underwater forests’:

You’ve said that “seaweeds are the ‘trees’ of the ocean”. Can you tell us a little more about your study organism, Phyllospora, and explain its importance for coastal ecosystems around Australia?

Phyllospora comosa (known locally as ‘crayweed’) grows up to 2.5 m in length and forms dense, shallow forests along the south-eastern coastline of Australia, from near Port Macquarie in New South Wales, around Tasmania to Robe in South Australia. Individuals appear to persist on reefs for around 2 years and are reproductive year round.

How do these ecosystems change with the reduction of seaweed forests?

Large, canopy-forming macroalgae provide structural complexity, food and habitat for coastal marine ecosystems and other marine organisms. When these habitat-formers decline or disappear, the ecosystem loses its complexity, biodiversity decreases and many ecosystem services are also lost. Losing large seaweeds from temperate reefs has analogous ecosystem-level implications to losing corals from tropical reefs.

We’re interested in learning more about how you got involved in this research. Can you tell us how you became interested in studying Phyllospora?

For my doctorate, I studied how changing environmental conditions may disrupt relationships between seaweeds and microorganisms – which are abundant and ubiquitous in marine environments – potentially leading to climate-mediated diseases. During my PhD, my colleagues (Coleman et al.) published a paper describing the disappearance of crayweed from the urbanised coastline of Sydney and hypothesised that the cause was the high volume, low treatment, near shore sewage outfalls that used to flow directly on to some beaches and bays in the city. I wondered whether this pollution may have disrupted the relationship between Crayweed and its microbial associates and that’s how I got involved in the project.

Why is the loss of canopy-forming macroalgae difficult to study retrospectively and how has this informed your current study?

Once an organism has disappeared from an ecosystem, it can be difficult to piece together the processes that caused its demise, particularly if the disappearance occurred several decades ago and the ecosystem state shifted dramatically as a consequence.  In our study, we hypothesized that poor water quality might have caused the decline of Phyllospora. There have been significant improvements in water quality in the region since the decline, but the species and ecosystems they used to support have failed to recover. To test whether the water quality has improved enough to allow recolonisation of this seaweed, we transplanted the seaweed back onto reefs where it was once abundant. The survival rates of transplanted seaweed were very good, suggesting that with a little help, this species may be able to recolonize Sydney’s reefs.

What were some of the difficulties you faced while conducting your research?

Moving hundreds of large seaweeds many kilometres from donor populations to the restoration sites was a big job. Thankfully, we received a great deal of help from many volunteers from the local community – mostly divers, with an interest in conserving and restoring the marine ecosystems they visit recreationally and value as a natural resource.

You’ve talked about Phyllospora ‘recruitment’ at one recipient site. Can you explain in greater detail what a ‘recruit’ is and how this is important for the success of a restoration site?

Phyllospora reproduces sexually, with gametes from male individuals fertilizing gametes from females, forming zygotes, which then attach themselves to the bottom (usually not very far from their parents) and grow into juvenile algae which we call ‘recruits’. In the context of restoration, the high level of recruitment (i.e. successful reproduction) we observed at our transplant site is very encouraging because it creates the possibility for the establishment of a self-sustaining population of Phyllospora at this site for the first time in many decades.

Why do seaweed forests receive less attention than other marine ecosystems, for example mangroves or coral reefs?

Most people don’t think about seaweeds very often. When they do, it’s usually because the sight, touch or smell of seaweed on the beach is annoying or offensive. Even the name “seaweed” conjures negative imagery so perhaps it’s a PR issue! Arguably, macroalgae have traditionally received less attention from marine ecologists than other marine ecosystems as well, with much more attention and funding going to coral reef research. With global patterns of declines of temperate, habitat-forming macroalgae, this needs to change and our understanding of the processes that affect seaweed populations needs to grow.

What would a successful restoration of underwater kelp forests mean for the ecosystem and for the local population?

It’s our hope that, by restoring habitat-forming macroalgae like Phyllospora, we will also enhance populations of other organisms that rely on this species for food or shelter. Detecting such follow-on benefits of our seaweed restoration program is the focus of ongoing research and our initial results are very encouraging.

You’ve mentioned that larger scale restoration would be a sound way of combating the grazing (herbivory) you saw. What is the next step forward for you?

Enhanced grazing may be another mechanism by which Phyllospora disappeared from these reefs (or perhaps why it’s failed to recover). The impacts of grazing we observed were site-specific, so further investigations in to why one place was so severely impacted by herbivores while the other was not, are needed. Our first step towards resolving this is to establish more numerous restoration patches of different sizes to see whether we can satiate the herbivores and whether smaller patches are more susceptible to grazing than larger patches.

For more PLOS ONE articles about the ‘trees of the ocean’, check out the way seaweed and coral interact in “Seaweed-Coral Interactions: Variance in Seaweed Allelopathy, Coral Susceptibility, and Potential Effects on Coral Resilience” and how ocean currents influence seaweed community organization in “The Footprint of Continental-Scale Ocean Currents on the Biogeography of Seaweeds”.

Citation: Campbell AH, Marzinelli EM, Vergés A, Coleman MA, Steinberg PD (2014) Towards Restoration of Missing Underwater Forests. PLoS ONE 9(1): e84106. doi:10.1371/journal.pone.0084106

Image: Adriana Vergés, co-author

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Unearthing the Environmental Impact of Cambodia’s Ancient City, Mahendraparvata

Angkor from the air

 

From the 9th to the mid-14th century, the region of Angkor in modern-day northern Cambodia was the capital of Khmer Empire and the largest preindustrial city in the world. Home to possibly more than three quarters of a million people, several different urban plans and reservoir systems, and impressive monuments like the temple of Angkor Wat (pictured from a bird’s-eye-view above), Angkor was the core of the Khmer Empire, which dominated Southeast Asia by the 11th century CE. Like many modern, booming cities, Angkor was fed by water sourced from another city.

Mahendraparvata, a hill-top site in the mountain range of Phnom Kulen, is significant as the birthplace of the Khmer Kingdom and as the seat of Angkor’s water supply. In 802 CE, Jayavarman II proclaimed himself the universal king of the Angkor region on the top of Mahendraparvata. Jayavarman’s ascension to power marked the unification of the Angkor region and the foundation of the Khmer Empire.

Figure1_PLOS_Pennyetal

 

Until recently, however, little was known about the urban settlement of Mahendraparvata; a dense forest canopy obscures a great deal of the area’s archaeological landscape. To determine the extent of land use around Mahendraparvata, the authors of a recent PLOS ONE paper examined soil core samples taken from one of the Phnom Kulen region’s reservoirs.

As Angkor’s source of water, Phnom Kulen’s archaeological landscape is littered with hydraulic structures, like dams, dykes, and reservoirs (points A, B, and E on the remote sensing digital image shown below), meant to store and direct Angkor’s water sources strategically. The researchers focused on an ancient reservoir upstream of the main river running north to south, now a swamp, to find evidence of intensive land use.

Remote sensing

 

Core samples taken from the sediment of this ancient reservoir, point F on the image above, provided the researchers with chronological layers of earth containing organic materials, like wood, pollens, and spores, which could be assessed using radiocarbon dating.

By analyzing the sediment cores, researchers found that the reservoir was likely in use for about 400 years. Although the age of the reservoir itself remains inconclusive, sediment samples suggest that the valley was flooded in the mid-to-late 8th century CE, around the time Jayavarman II unified the area.

The authors found that medium-to-coarse sand deposition in the sediment samples beginning in the mid-9th century points to the presence of continual soil erosion, either from the surrounding hills or from the dyke itself, likely caused by deforestation in the area. By analyzing samples from the late 11th century, the authors found that the last and largest episode of erosion occurred, a possible result of intensive land use.

The researchers suggest that deforestation, as evidenced by soil erosion, implies that “settlement on Mahendraparvata was not only spatially extensive but temporally enduring.” In other words, the estimated extent of deforestation by continual sand deposits from the mid-9th century to the late-11th century in core samples indicates that Mahendraparvata was home to a large and thriving urban network in need of resources.

However, an increase in pollen spores dated to the 11th century, followed by the establishment of swamp forests in the early to mid-12th century in the reservoir, reflects that, by this time, the reservoir had fallen out of use, perhaps linked to changes in water management throughout the broader area, and possible population decline nearby. According to mid-16th century samples, the swamp flora around this time appears to have developed into the swamp flora seen today in the ruins of Mahendraparvata.

For some 400 years, the Phnom Kulen mountains acted as the main source of water for the Angkor region. The change of water management practices in the Phnom Kulen region has implications for the water supply to Angkor itself. In sum, by examining core samples drawn from one of Phnom Kulen’s ancient reservoirs, authors were able to explore an archaeological landscape that is still largely hidden and a history still mainly obscured by time. The potential link between the rise and fall of urban life in the Angkor region and the use of reservoirs like the one used in this study helps to unearth a little bit more about the the Khmer Kingdom and the marked environmental impact of Mahendraparvata.

Citation: Penny D, Chevance J-B, Tang D, De Greef S (2014) The Environmental Impact of Cambodia’s Ancient City of Mahendraparvata (Phnom Kulen). PLoS ONE 9(1): e84252. doi:10.1371/journal.pone.0084252

Image 1: Angkor Wat by Mark McElroy

Image 2: journal.pone.0084252

Image 3: journal.pone.0084252

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Watch Where I’m Going: Predicting Pedestrian Flow

Pedestrian traffic flow

Pedestrian traffic flow

At last check, the population of the world was around 7.1 billion and counting.  As we all know, the sheer number of people on the planet presents a host of new challenges and exacerbates existing ones.  The overarching population problem may seem daunting, but there’s still plenty we can do to make a crowded, urbanized world livable.  A new study in PLOS ONE focuses on the specific issue of pedestrian traffic and how to accurately model the flow of people through their environment.

Researchers with Siemens and the Munich University of Applied Sciences examined video recordings of commuters walking through a major German train station on a weekday, during both the morning and evening peak commute times. Scientists analyzed the videos to determine individual pedestrians’ paths and walking speeds, and used the resulting data to set the parameters for a simulation of pedestrian traffic flow.  According to the authors, this kind of calibration of theoretical models using real-world data is largely missing from the most pedestrian flow models, which are under-validated and imprecise.

Footage from train station

Footage from train station

The authors utilized a cellular automaton model to form the basis of this simulation. Cellular automatons are models in which cells in a grid evolve and change values through steps based on specific rules. In this instance, the authors used a hexagonal grid and a few simple rules about pedestrian movement:

  • Pedestrians know and will follow the shortest path to their destination unless pedestrians or other obstacles are in the way.
  • Pedestrians will walk at their own individual preferred speeds, so long as the path is unobstructed.
  • Individuals need personal space, which acts like a repelling force to other pedestrians and objects.
  • Walking speeds decrease as crowds get denser.
  • Factors like age and fitness are all captured by setting a range of individual walking speeds.
Pedestrian traffic flow model

Pedestrian traffic flow model (Settlers of Catan Pedestrian Expansion?)

This model also borrowed from electrostatics by treating people like electrons. As the authors write:

“Pedestrians are attracted by positive charges, such as exits, and repelled by negative charges, such as other pedestrians or obstacles.”

Add to this model rules about when and where pedestrians appear, the starting points and destinations, and the relative volume of traffic from each starting point to different destinations, and you’ve got a basic model of pedestrian traffic.

Next, the authors calibrated this model by setting parameters using real-world, observational data from the train station videos:  where people at each starting point were going, distance kept from walls, the distribution of walking speeds, and so on.  To test their model and parameters, the authors validated it by running predictive simulations and comparing it to real-world scenarios. Based on the results, the authors suggest that this kind of model, which includes parameters based on real-world observation, more accurately represents pedestrian flow than other models of walkers that do not incorporate observational data.

The authors also changed multiple parameters to determine which ones had the largest impact on the simulation. The parameter that had the largest effect when altered was the source-target distribution (the destinations of people coming from specific starting points), so the authors note that this is critical to measure accurately and precisely.

The ability to precisely predict the flow of traffic has many clear applications, from the design of buildings and public spaces to the prediction and prevention of unsafe crowd densities during large events or emergencies.

Next research question: when it’s crowded, does pushing really not make it go faster?

Related papers:

Citation: Davidich M, Köster G (2013) Predicting Pedestrian Flow: A Methodology and a Proof of Concept Based on Real-Life Data. PLoS ONE 8(12): e83355. doi:10.1371/journal.pone.0083355

Images: All images come from the manuscript

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Rainforest Fungi Find Home in Sloth Hair

Bradypus_variegatusMost of us have seen a cute sloth video or two on the Internet. Their squished faces, long claws, and scruffy fur make these slow-moving mammals irresistible, but our furry friends aren’t just amusing Internet sensations. Like most inhabitants of the rainforest, little is known about the role sloths play in the rainforest ecosystem.

Three-toed sloths live most of their lives in the trees of Central and South American rainforests. Rainforests are some of the most biodiverse ecosystems in the world and home to a wide variety of organisms, some of which can be found in rather unusual places.

Due to their vast biodiversity, rainforests have been the source for a wide variety of new medicines, and researchers of this PLOS ONE study sought to uncover whether sloth hair may also contain potential new sources of drugs that could one day treat vector-borne diseases, cancer, or bacterial infections. Why look in sloth fur? It turns out that sloths carry a wide variety of micro- and macro-organisms in their fur, which consists of two layers: an inner layer of fine, soft hair close to the skin, and a long outer layer of coarse hair with “cracks” across it where microbes make their homes. The most well-known inhabitant of sloth fur is green algae. In some cases, the green algae makes the sloth actually appear green, providing a rainforest camouflage.

In the study, seventy-four separate fungi were obtained from the surface of coarse outer hair that were clipped from the lower back of nine living three-toed sloths in Soberanía National Park, Panama, and were cultivated and tested for bioactivity in the lab.

Researchers found a broad range of in vitro activities of the fungi against bugs that cause malaria and Chagas disease, as well as against a specific type of human breast cancer cells. In addition, 20 fungal extracts were active in vitro against at least one bacterial strain. The results may provide for the first time an indication of the biodiversity and bioactivity of microorganisms in sloth hair.

Since sloths are moving around in one of the most diverse ecosystems in the world, it’s possible that they may pick up “hitchhikers,” so the researchers can’t be sure how these fungi came to live on the sloth fur. They may even have a symbiotic relationship with the green algae. However the fungi ended up in the fur, the authors suggest their presence in the ecosystem provides support for the role biodiversity plays both in the rainforest and potentially our daily lives.

Citation: Higginbotham S, Wong WR, Linington RG, Spadafora C, Iturrado L, et al. (2014) Sloth Hair as a Novel Source of Fungi with Potent Anti-Parasitic, Anti-Cancer and Anti-Bacterial Bioactivity. PLoS ONE 9(1): e84549. doi:10.1371/journal.pone.0084549

Image: Bradypus variegates by Christian Mehlführer

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Resolution Inspiration: What Will You Work on in 2014?

Resolutions 2012 - Flickr - Lori Ann

Though we are well into January, there is still time to set resolutions for 2014. What would you like to accomplish in the next twelve months? For some resolution inspiration, here’s a selection of PLOS ONE research articles to get you started:

Restaurant Bwyty sign by Dave GoodmanLearn a Language

Whether for work or pleasure, learning a new language can be a rewarding experience. It can also take a lot of time. Fear not—according to research published last year, you may be able to learn new words in a foreign language while performing other tasks. The key to this method of vocabulary building is exposure. In the study, participants were given a letter and tasked with finding the letter in a written Welsh word. As they looked for the letter, one group informally heard the word and saw an image of what it represented. Afterward, when participants were asked to determine whether a Welsh word matched an image, those who were exposed to corresponding images and audio scored higher than their counterparts in the control group.

 

Sing Along with Me (10 365) by John Liu

Get Vocal

For those of you with musical aspirations, take a nod from this study on vocal synchronization and rhythm. In it the researchers found that when participants read aloud together in real time, their speech patterns synchronized more readily than participants who read aloud with the recording of their partner’s voice. Though the study was primarily concerned with spoken rhythms, the researchers propose that the social component of rhythm, and the shared goal of synchronization, may be pertinent to music too. Musical rhythm, they suggest, may stem from social interaction rather than sexual selection.

 

smile by jessicahtamDe-stress

Under pressure? According to the authors of this next PLOS ONE paper, those who experience chronic stress may suffer from impaired problem-solving skills. To combat the deleterious effects of stress, they suggest performing a “self-affirmation” exercise before tackling a problem. In the study, the researchers asked underperforming and self-reportedly stressed college students to rank a series of values, such as creativity and friends/family, according to order of personal importance. They were then asked to write about why the top value was most important to them, or why one of the bottom values might be important to others. After completing the exercise, the students were given a word association test. Stressed-out students that wrote about their top value and its personal importance outperformed their peers. Talk about the power of positive thinking!

Whether you want to pick up a new language, reduce your stress, or get out and sing more karaoke this year, we hope you are inspired to try out a few resolutions. For even more inspiration, check out other posts in the PLOS Blogs network: Alessandro Demaio’s Translational Global Health and Peter Janiszewski’s post on Obesity Panacea.

 

Citations:

Bisson M-J, van Heuven WJB, Conklin K, Tunney RJ (2013) Incidental Acquisition of Foreign Language Vocabulary through Brief Multi-Modal Exposure. PLoS ONE 8(4): e60912. doi:10.1371/journal.pone.0060912

Bowling DL, Herbst CT, Fitch WT (2013) Social Origins of Rhythm? Synchrony and Temporal Regularity in Human Vocalization. PLoS ONE 8(11): e80402. doi:10.1371/journal.pone.0080402

Creswell JD, Dutcher JM, Klein WMP, Harris PR, Levine JM (2013) Self-Affirmation Improves Problem-Solving under Stress. PLoS ONE 8(5): e62593. doi:10.1371/journal.pone.0062593

 

Image: Resolutions 2012 by Lori Ann

Restaurant Bwyty sign by Dave Goodman

Sing Along with Me (10/365) by John Liu

Smile by jessicatam

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A Year in Review: 2013 PLOS ONE Papers in the Media

 

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Tired of year-end lists? We know you’ve got room for at least one more. 2013 was a great year for PLOS ONE media coverage: We had over 5,000 news stories on over 1450 published articles.

The PLOS ONE press team poured tirelessly over the list to whittle down the papers that stood out the most. In celebration of the New Year, we’d like to share some of these titles with you.

Zipping back to January 2013 and moving forward from there, here they are:

 

1. Flowers Flowering Faster (Sooner)

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In “Record-Breaking Early Flowering in the Eastern United States,” US researchers used 161 years of historical reports—initiated by Henry David Thoreau and Aldo Leopold in 1935—to track spring flowering times. They discovered that exceptionally warm spring temperatures in Massachusetts and Wisconsin in 2010 and 2012 may have resulted in the earliest recorded spring in the eastern United States. Furthermore, scientists indicate that these advanced flowering times could be predicted based on the historical data. This research received media attention from the The New York Times, National Geographic, and NPR.

 

2. Lend an Ear?

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US scientists 3D-printed a human ear using collagen hydrogels (a network of polymers that form a gel with water) derived from cow cartilage in the lab. They shared their results in “High-Fidelity Tissue Engineering of Patient-Specific Auricles for Reconstruction of Pediatric Microtia and Other Auricular Deformities.” The authors suggest that this advancement may be a significant first step toward creating patient-specific tissue implants for those who require ear prosthesis. Popular Science, Discovery News, and NPR covered this research.

 

3. Central African Elephants in Big Trouble

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African forest elephant populations may have declined by an alarming 62% in the last decade, according to the study “Devastating Decline of Forest Elephants in Central Africa.” The authors suggest that this dramatic drop is largely due to continuing illegal ivory trade and inadequate efforts to put a stop to it. ScienceNow, TIME, Slate, Smithsonian, and many others covered this article.

 

4. Wrapped up in a Book

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For everyone who enjoys a good page-turner, researchers in the study “The Expression of Emotions in 20th Century Books” indicate that recent British and American books have fewer emotional “mood” words than they did in the earlier half of the 20th century. What’s more, the study’s authors provide evidence that American authors express more emotion than British authors, and that newer American books use more words conveying fear than older ones. This research was covered by the The New York Times Arts Beat, Jezebel, our EveryONE blog, and Nature.

 

5. Gaming for All Ages

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In the article “A Randomized Controlled Trial of Cognitive Training Using a Visual Speed of Processing Intervention in Middle Aged and Older Adults,” researchers from multiple institutions in Iowa discovered that when middle-aged and older adults played video games, they scored better on cognitive function tests. The authors hope that these results might help us slow cognitive decline in older individuals. This paper was covered by the The Wall Street Journal, Nature, and The Telegraph.

 

6. Seafood Watch for Arctic Foxes?

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In another saddening story of declining wild animal populations, researchers studying the “Correlates between Feeding Ecology and Mercury Levels in Historical and Modern Arctic Foxes (Vulpes lagopus)” found that mercury levels in seafood may be the culprit. They emphasize that overall direct exposure to toxic materials may not be as important as the feeding ecology and opportunities of predators, like the arctic fox, that have a very marine-based diet, which may contain these toxic substances. This research received media attention from Wired UK, Scientific American, and The Guardian.

 

7. Cancer in Neandertals

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At least one Neandertal 120,000 years ago had a benign bone tumor in a rib, according to researchers in the study “Fibrous Dysplasia in a 120,000+ Year Old Neandertal from Krapina, Croatia.” The authors note, however, that they cannot comment on any health effects or the overall health condition of the individual without further evidence. This article received media attention from sources including the BBC, The New York Times, ScienceNOW, and Gizmodo.

 

8. Who Needs Rows of Teeth When You’ve Got a Tail to Slap Sardines?

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Image credit: PLOS ONE article

Thresher Sharks Use Tail-Slaps as a Hunting Strategy” contains the first video evidence of long-tailed sharks tail-slapping to stun their sardine prey. The authors suggest that this method may be effective when hunting prey that swim in schools. A Scientific American podcast, National Geographic’s Phenomena blogs, and NBC News were some of the media outlets that covered this research.

 

9. Contagious Yawning in Dogs and Chimps

Video credit: PLOS ONE article

Yawning animals were the focus of more than one PLOS ONE article in 2013. In one study, “Familiarity Bias and Physiological Responses in Contagious Yawning by Dogs Support Link to Empathy,” Japanese researchers found that dogs yawn more often in response to their owners’ yawns rather than a stranger’s, and received media coverage from The Guardian, CBS News, and The Telegraph. The authors of another research article “Chimpanzees Show a Developmental Increase in Susceptibility to Contagious Yawning: A Test of the Effect of Ontogeny and Emotional Closeness on Yawn Contagion” showed that chimpanzees appear to develop a contagion for yawning as they get older, just as humans do, and this article received media attention from The New York Times Science Takes, Los Angeles Times, and Scientific American Blogs.

 

10. What, the Cat? Oh, He’s Harml…

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Our favorite parasite Toxoplasma gondii strikes again. Mice are normally terrified of cats, and rightly so, but Berkeley researchers (including a PLOS founder Mike Eisen) in “Mice Infected with Low-Virulence Strains of Toxoplasma gondii Lose Their Innate Aversion to Cat Urine, Even after Extensive Parasite Clearance” show that mouse exposure to the parasite, carried in cat feces, may alter the mouse’s brain, causing the mouse to permanently lose its fear of cats. The story received coverage from several news outlets, including a CNN segment by Charlie Rose, and coverage by BBC, National Geographic Phenomena, and Nature.

 

11. Just in Time for the Movie: Jurassic Park is Fake

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Sorry in advance for the disheartening news: Jurassic Park will likely remain a work of fiction. In “Absence of Ancient DNA in Sub-Fossil Insect Inclusions Preserved in ‘Anthropocene’ Colombian Copal,” UK researchers were unable to find any evidence of ancient DNA in specimens of prehistoric insects fossilized in hardened tree sap. Conveniently, the article published right when the newest Jurassic Park film series was announced, and was covered by San Francisco Chronicle, The Telegraph, The Conversation, and others.

 

12. Not Now, Honey – The Pressure Just Dropped

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Insects avoid sex when a drop in atmospheric pressure occurs, which usually precedes rain, according to researchers in the study “Weather Forecasting by Insects: Modified Sexual Behaviour in Response to Atmospheric Pressure Changes.” Injury from rain can be deadly for some insect species, so the authors suggest that the insects modified their behavior to enhance survival (good choice!). The article has received attention from nearly 20 news outlets, including Nature, Los Angeles Times, Scientific American, and ScienceNOW.

 

13. Dinos with Squishy Joints and Tiny Arms

 

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Image credit: PLOS ONE article

Dinosaurs were a popular item in PLOS ONE in 2013, especially with the launch of PLOS ONE’s New Sauropod Gigantism Collection. The most popular article was a simulation of how the largest dinosaur, the Argentinosaurus, might have walked in “March of the Titans: The Locomotor Capabilities of Sauropod Dinosaurs,” which was covered in Washington Post and The Guardian. Another group of researchers showed that squishy joints were a major factor in the massiveness of saurischian dinosaurs in “What Lies Beneath: Sub-Articular Long Bone Shape Scaling in Eutherian Mammals and Saurischian Dinosaurs Suggests Different Locomotor Adaptations for Gigantism.” The article was covered by Gizmodo, Inside Science, and Discovery. Finally, a new super-predator larger than T. rex lived 80 million years ago and was described in “Tyrant Dinosaur Evolution Tracks the Rise and Fall of Late Cretaceous Oceans” and covered by BBC, Nature, and Discovery.

 

14. Huh?

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The title of this next study says it all: “Is “Huh?” a Universal Word? Conversational Infrastructure and the Convergent Evolution of Linguistic Items.” The authors of this article suggest that it is, and that at least ten countries use a variation of this word to verbally express confusion. The article was featured in NPR, The New York Times, and LA Times.

 

15. Little Red Riding Hood: The Evolution of a Folk Tale

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Little Red Riding Hood has very deep roots, as the authors of “The Phylogeny of Little Red Riding Hood” show in their article. It has made its way across China to Europe and back again, but where did it begin? The authors indicate that phylogenetic methods (like the branched chart above) may be a new way to analyze cultural relationships among folk tales and oral narratives. This article received coverage in ScienceNOW, National Geographic, and Nature.

Thank you to all of our Academic Editors, reviewers, and authors for making these articles a reality. Needless to say, PLOS ONE staff cannot wait to see what lies ahead in 2014!

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