But how does this intricate system ensure that more active parts of the brain receive enough nourishment versus less demanding areas? That’s a century-old problem in neuroscience that scientists at the University of California San Diego have helped answer in a newly published study.

Studying the brains of mice, a team of researchers led by Xiang Ji, David Kleinfeld and their colleagues has deciphered the question of brain energy consumption and blood vessel density through newly developed maps that detail brain wiring to a resolution finer than a millionth of a meter, or one-hundredth of the thickness of a human hair.

A result of work at the crossroads of biology and physics, the new maps provide novel insights into these “microvessels” and their various functions in blood supply chains. The techniques and technologies underlying the results are described March 2 in the journal Neuron.

“We developed an experimental and computational pipeline to label, image and reconstruct the microvascular system in whole mouse brains with unprecedented completeness and precision,” said Kleinfeld, a professor in the UC San Diego Department of Physics (Division of Physical Sciences) and Section of Neurobiology (Division of Biological Sciences). Kleinfeld says the effort was akin to reverse engineering nature. “This allowed Xiang to carry out sophisticated calculations that not just related brain energy use to vessel density, but also predicted a tipping point between the loss of brain capillaries and a sudden drop in brain health.”

Questions surrounding how blood vessels carry nourishment to active and less active regions were posed as a general issue in physiology as far back as 1920. By the 1980s, a technology known as autoradiography, the predecessor of modern-day positron emission tomography (PET), allowed scientists to measure the distribution of sugar metabolism across the mouse brain.

To fully grasp and solve the problem, Ji, Kleinfeld and their colleagues at the Howard Hughes Medical Institute’s Janelia Research Campus and UC San Diego Jacobs School of Engineering filled 99.9 percent of the vessels in the mouse brain — a count of nearly 6.5 million — with a dye-labeled gel. They then imaged the full extent of the brain with sub-micrometer precision. This resulted in fifteen trillion voxels, or individual volumetric elements, per brain, that were transformed into a digital vascular network that could be analyzed with the tools of data science.

With their new maps in hand, the researchers determined that the concentration of oxygen is roughly the same in every region of the brain. But they found that small blood vessels are the key components that compensate for varying energy requirements. For example, white matter tracts, which transfer nerve impulses across the two brain hemispheres and to the spinal cord, are regions of low energy needs. The researchers identified lower levels of blood vessels there. By contrast, brain regions that coordinate the perception of sound use three times more energy and, they discovered, were found with a much greater level of blood vessel density.

“In the era of increasing complexities being unraveled in biological systems, it is fascinating to observe the emergence of shared simple and quantitative design rules underlaying the seemingly complicated networks across mammalian brains,” said Ji, a graduate student in physics.

Up next, the researchers hope to drill down into the finer aspects of their new maps to determine the detailed patterns of blood flow into and out from the entire brain. They will also pursue the largely uncharted relationship between the brain and the immune system.

Authors on the paper include Xiang Ji, Tiago Ferreira, Beth Friedman, Rui Liu, Hannah Liechty, Erhan Bas, Jayaram Chandrashekar and David Kleinfeld.

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Materials provided by University of California – San Diego. Original written by Mario Aguilera. Note: Content may be edited for style and length.

Every aspect of modern computing, from the smallest chip to the largest data center comes with a carbon price tag. For the better part of a century, the tech industry and the field of computation as a whole have focused on building smaller, faster, more powerful devices — but few have considered their overall environmental impact.

Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) are trying to change that.

“Over the next decade, the demand, number and types of devices is only going to grow,” said Udit Gupta, a PhD candidate in Computer Science at SEAS. “We want to know what impact that will have on the environment and how we, as a field, should be thinking about how we adopt more sustainable practices.”

Gupta, along with Gu-Yeon Wei, the Robert and Suzanne Case Professor of Electrical Engineering and Computer Science, and David Brooks, the Haley Family Professor of Computer Science, will present a paper on the environmental footprint of computing at the IEEE International Symposium on High-Performance Computer Architecture on March 3rd, 2021.

The SEAS research is part of a collaboration with Facebook, where Gupta is an intern, and Arizona State University.

The team not only explored every aspect of computing, from chip architecture to data center design, but also mapped the entire lifetime of a device, from manufacturing to recycling, to identify the stages where the most emissions occur.

The team found that most emissions related to modern mobile and data-center equipment come from hardware manufacturing and infrastructure.

“A lot of the focus has been on how we reduce the amount of energy used by computers, but we found that it’s also really important to think about the emissions from just building these processors,” said Brooks. “If manufacturing is really important to emissions, can we design better processors? Can we reduce the complexity of our devices so that manufacturing emissions are lower?”

Take chip design, for example.

Today’s chips are optimized for size, performance and battery life. The typical chip is about 100 square millimeters of silicon and houses billions of transistors. But at any given time, only a portion of that silicon is being used. In fact, if all the transistors were fired up at the same time, the device would exhaust its battery life and overheat. This so-called dark silicon improves a device’s performance and battery life but it’s wildly inefficient if you consider the carbon footprint that goes into manufacturing the chip.

“You have to ask yourself, what is the carbon impact of that added performance,” said Wei. “Dark silicon offers a boost in energy efficiency but what’s the cost in terms of manufacturing? Is there a way to design a smaller and smarter chip that uses all of the silicon available? That is a really intricate, interesting, and exciting problem.”

The same issues face data centers. Today, data centers, some of which span many millions of square feet, account for 1 percent of global energy consumption, a number that is expected to grow.

As cloud computing continues to grow, decisions about where to run applications — on a device or in a data center — are being made based on performance and battery life, not carbon footprint.

“We need to be asking what’s greener, running applications on the device or in a data center,” said Gupta. “These decisions must optimize for global carbon emissions by taking into account application characteristics, efficiency of each hardware device, and varying power grids over the day.”

The researchers are also challenging industry to look at the chemicals used in manufacturing.

Adding environmental impact to the parameters of computational design requires a massive cultural shift in every level of the field, from undergraduate CS students to CEOs.

To that end, Brooks has partnered with Embedded EthiCS, a Harvard program that embeds philosophers directly into computer science courses to teach students how to think through the ethical and social implications of their work. Brooks is including an Embedded EthiCS module on computational sustainability in COMPSCI 146: Computer Architecture this spring.

The researchers also hope to partner with faculty from Environmental Science and Engineering at SEAS and the Harvard University Center for the Environment to explore how to enact change at the policy level.

“The goal of this paper is to raise awareness of the carbon footprint associated with computing and to challenge the field to add carbon footprint to the list of metrics we consider when designing new processes, new computing systems, new hardware, and new ways to use devices. We need this to be a primary objective in the development of computing overall,” said Wei.

The paper was co-authored by Sylvia Lee, Jordan Tse, Hsien-Hsin S. Lee and Carole-Jean Wu from Facebook and Young Geun Kim from Arizona State University.

Connected and automated vehicles, which can interact vehicle to vehicle (V2V) and between vehicles and roadway infrastructure like traffic signals and stop signs (V2I), promise to save energy and improve safety. In a new study published in Transportation Research Part B, engineers from Michigan Technological University propose a modeling framework for V2V and V2I cooperative driving.

Cooperative driving helps cars and their drivers safely and efficiently navigate. The framework uses an eco-driving algorithm that prioritizes saving fuel and reducing emissions. The automated algorithm calculates location-based traffic control devices and roadway constraints using maps and geographic information. The research is led by Kuilin Zhang, associate professor of civil and environmental engineering and affiliated associate professor of computer science at Michigan Tech, along with Shuaidong Zhao ’18, now a senior quantitative analyst at National Grid.

For the past three years, Houghton, Michigan, has been home to roadside units installed on five of the city’s traffic signals that make V2I communication possible. Zhang conducted a simulation analysis using real traffic signal phasing and timing messages from the Ann Arbor connected vehicle test environment and plans to expand testing in the Houghton area.

“The whole idea of cooperative driving automation is that the signals in the intersection tell your car what’s happening ahead,” Zhang said. “The sensor at the intersection can benefit all connected vehicles passing through the intersection. The automated eco-driving algorithm improves the driving decisions of the connected and automated vehicles.”

The simulation results show that the cooperative automated eco-driving algorithm saves energy — 7% under light traffic and 23% under heavy traffic along the corridor.

“The stop and go, stop and go, it may use a lot of energy,” Zhang said. “The concept of eco-driving incorporates how the vehicle makes driving decisions using data not only from vehicles in front of it, but also with information given from a traffic signal.”

Zhang’s model pulls in high-definition (HD) maps, which use a connected vehicle’s hardware and software to provide down-to-the-centimeter accuracy in navigation. HD maps incorporate multiple types of environmental sensing: long-range radar, lidar, camera footage, short/medium-range radar and ultrasound.

Zhang said for autonomous driving, it’s important to know landmarks to control the car’s driving, as well as hill grades; using a hill to slow or accelerate a car can also increase energy savings. It’s easy to conserve energy on a straight highway; on busy arterial streets with traffic and stoplights, energy conservation isn’t so simple. On city streets, Zhang and Zhao’s online predictive connected and automated eco-driving model considers traffic control devices and road geometry constraints under light and heavy traffic conditions.

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Materials provided by Michigan Technological University. Original written by Kelley Christensen. Note: Content may be edited for style and length.

The Mediterranean monk seal is classified as “endangered,” with a total population of about 700.

The new study — by the University of Exeter and the Society for the Protection of Turtles (SPOT) — used camera-traps to confirm breeding in caves in northern Cyprus, with at least three pups born from 2016-19 at one cave.

Only certain caves are suitable for monk seal breeding and resting, so — although the numbers are small — the researchers say urgent action is needed to protect these caves.

“This area of coastline in being developed rapidly, especially for construction of hotels,” said Dr Robin Snape, of the Centre for Ecology and Conservation on Exeter’s Penryn Campus in Cornwall.

“A survey of the coast in 2007 found 39 possible breeding caves, and some of these have already been destroyed.

“The main breeding site we identify in this study currently has no protected status, and we are working with local authorities to try to change this.”

Lead author Dr Damla Beton, of SPOT, added: “Another major threat to monk seals in this area is bycatch (accidental catching by fisheries).

“We are working with fishers and government ministries to ensure protection areas at sea, because at present no measures are implemented to mitigate bycatch in the core areas used by these seals.”

The team has now established long-term monitoring of the breeding caves, aiming to determine the size of this seal population.

The study, carried out in collaboration with the Middle Eastern Technical University with the support of the local authorities, received funding from the MAVA Foundation.

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Materials provided by University of Exeter. Note: Content may be edited for style and length.

Although biochemical and optical methods exist, mechanical techniques are the most widely used. They indirectly assess ripeness based on the fruit’s firmness. In turn, firmness is quantified by observing the vibrations that occur on the fruit when mechanical energy is accurately delivered through devices such as hammers, pendulums, or speakers. Unfortunately, these approaches fall short for softer fruits, which are more readily damaged by the contact devices used.

In a recent study published in Foods, a team of scientists from Shibaura Institute of Technology (SIT), Japan, addressed this issue through an innovative method for measuring the firmness of soft fruits using laser-induced plasma (LIP). This work is a sort of follow-up of a previous study in which LIP was used to quantify the firmness of harder fruits.

But what is LIP and how is it used? Plasma is a state of matter similar to the gaseous state but in which most particles have an electric charge. This energetic state can be produced in normal air by focusing a high-intensity laser beam onto a small volume. Because the generated plasma “bubble” is unstable, it immediately expands, sending out shockwaves at ultrasonic speeds. Professor Naoki Hosoya and colleagues at SIT had successfully used LIP shockwaves generated close to the surface of apples to excite a type of vibration called ₀S₂ mode, colloquially referred to as “football mode vibration” because of how the resulting deformation looks on spherical bodies. They then verified that the frequency of the ₀S₂ mode vibrations was correlated with the firmness of the fruit.

However, soft fruits do not exhibit ₀S₂ mode vibrations, so the team had to analyze an alternative type of oscillation: Rayleigh waves. These are waves that occur exclusively on the surface of bodies without penetrating far into the interior. Using Kent mangoes, a setup for generating LIP, and commercially available laser-based vibrometers, the scientists verified that the velocity at which Rayleigh waves propagate is directly related to the firmness of the mangoes. Because the propagation velocity markedly decreases with storage time, it provides a reliable way to indirectly assess ripeness.

The team went further and looked for the best position on the mangoes’ surface to determine the velocity of Rayleigh waves. Mangoes, as well as other soft fruits, have large seeds inside, which can alter the propagation of surface waves in ways that are detrimental to measurements. “The results of our experiments indicate that Rayleigh waves along the ‘equator’ of the mango are better for firmness assessment compared to those along the ‘prime meridian’,” explains Hosoya. The experiments also revealed that cavities within the fruit’s flesh or decay can greatly affect the results of the measurements. Thus, as Hosoya adds, they will keep investigating which is the best area to measure firmness in mangoes using their novel approach.

In short, the team at SIT has engineered an innovative strategy to assess the ripeness of soft fruits from outside. “Our system,” remarks Hosoya, “is suitable for non-contact and non-destructive firmness assessment in mangoes and potentially other soft fruits that do not exhibit the usual ₀S₂ mode vibrations.” Further refinement of such firmness assessment methods will hopefully make them more reliable and accessible for the agricultural industry. With any luck, their widespread adoption will ensure that fruits reach your plate only when the time is ripe!

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Materials provided by Shibaura Institute of Technology. Note: Content may be edited for style and length.