Tag Archives: #body

New Wearable Device Turns The Body Into a Battery (Engineering)

Researchers at the University of Colorado Boulder have developed a new, low-cost wearable device that transforms the human body into a biological battery. 

The device, described today in the journal Science Advances, is stretchy enough that you can wear it like a ring, a bracelet or any other accessory that touches your skin. It also taps into a person’s natural heat—employing thermoelectric generators to convert the body’s internal temperature into electricity. 

“In the future, we want to be able to power your wearable electronics without having to include a battery,” said Jianliang Xiao, senior author of the new paper and an associate professor in the Paul M. Rady Department of Mechanical Engineering at CU Boulder.

The concept may sound like something out of The Matrix film series, in which a race of robots have enslaved humans to harvest their precious organic energy. Xiao and his colleagues aren’t that ambitious: Their devices can generate about 1 volt of energy for every square centimeter of skin space—less voltage per area than what most existing batteries provide but still enough to power electronics like watches or fitness trackers. 

Scientists have previously experimented with similar thermoelectric wearable devices, but Xiao’s is stretchy, can heal itself when damaged and is fully recyclable—making it a cleaner alternative to traditional electronics. 

“Whenever you use a battery, you’re depleting that battery and will, eventually, need to replace it,” Xiao said. “The nice thing about our thermoelectric device is that you can wear it, and it provides you with constant power.”

High-tech bling

The project isn’t Xiao’s first attempt to meld human with robot. He and his colleagues previously experimented with designing “electronic skin,” wearable devices that look, and behave, much like real human skin. That android epidermis, however, has to be connected to an external power source to work.  

Until now. The group’s latest innovation begins with a base made out of a stretchy material called polyimine. The scientists then stick a series of thin thermoelectric chips into that base, connecting them all with liquid metal wires. The final product looks like a cross between a plastic bracelet and a miniature computer motherboard or maybe a techy diamond ring.  

“Our design makes the whole system stretchable without introducing much strain to the thermoelectric material, which can be really brittle,” Xiao said.

Just pretend that you’re out for a jog. As you exercise, your body heats up, and that heat will radiate out to the cool air around you. Xiao’s device captures that flow of energy rather than letting it go to waste.

“The thermoelectric generators are in close contact with the human body, and they can use the heat that would normally be dissipated into the environment,” he said.

Lego blocks

He added that you can easily boost that power by adding in more blocks of generators. In that sense, he compares his design to a popular children’s toy. 

“What I can do is combine these smaller units to get a bigger unit,” he said. “It’s like putting together a bunch of small Lego pieces to make a large structure. It gives you a lot of options for customization.”

Xiao and his colleagues calculated, for example, that a person taking a brisk walk could use a device the size of a typical sports wristband to generate about 5 volts of electricity—which is more than what many watch batteries can muster.

Like Xiao’s electronic skin, the new devices are as resilient as biological tissue. If your device tears, for example, you can pinch together the broken ends, and they’ll seal back up in just a few minutes. And when you’re done with the device, you can dunk it into a special solution that will separate out the electronic components and dissolve the polyimine base—each and every one of those ingredients can then be reused.

“We’re trying to make our devices as cheap and reliable as possible, while also having as close to zero impact on the environment as possible,” Xiao said.

While there are still kinks to work out in the design, he thinks that his group’s devices could appear on the market in five to 10 years. Just don’t tell the robots. We don’t want them getting any ideas. 

Coauthors on the new paper include researchers from China’s Harbin Institute of Technology, Southeast University, Zhejiang University, Tongji University and Huazhong University of Science and Technology.

Featured image: A thermoelectric wearable device worn as a ring. (Credit: Xiao Lab)


Reference: Wei Ren, Yan Sun, Dongliang Zhao, Ablimit Aili, Shun Zhang, Chuanqian Shi, Jialun Zhang, Huiyuan Geng, Jie Zhang, Lixia Zhang, Jianliang Xiao, Ronggui Yang, “High-performance wearable thermoelectric generator with self-healing, recycling, and Lego-like reconfiguring capabilities”, Science Advances  10 Feb 2021: Vol. 7, no. 7, eabe0586 DOI: 10.1126/sciadv.abe0586


Provided by University of Colorado Boulder

Children Rely on What They Hear When Detecting Emotions (Psychology)

Children determine emotion through hearing rather than seeing, our researchers have found.

Children determine emotion through hearing rather than seeing, our researchers have found.

First-of-its-kind study

In a first-of-its-kind study, our Department of Psychology looked at how children pick up on the emotions of a situation.

They found that whilst adults prioritised what they see, young children overwhelmingly prioritised what they could hear, known as ‘auditory dominance’.

The findings could benefit both education professionals and parents currently managing home learning, by increasing their understanding of how young children pick up on what is going on around them.

It could also provide new avenues to understanding emotional recognition in children with developmental challenges such as autism.

Age and emotional assessment

Volunteers in three age categories (seven and under, eight to 11, and 18+) were shown pictures of humans, with faces blurred, and played human voices, which conveyed happy and fearful and sad and angry emotions.

The pictures and sounds were presented both on their own, and in corresponding and contrasting combinations, and the volunteers were asked what the over-riding emotion was in each.

The team found that adults based their emotional assessment on what they could see whereas young children relied on what they could hear.

Our researchers now plan to investigate whether young children still rely on what they can hear when they can see human facial expressions and when human voices are replaced with music conveying similar emotions.


Reference: Paddy Ross, Beth Atkins, Laura Allison, Holly Simpson, Catherine Duffell, Matthew Williams, Olga Ermolina, Children cannot ignore what they hear: Incongruent emotional information leads to an auditory dominance in children, Journal of Experimental Child Psychology, Volume 204, 2021, 105068, ISSN 0022-0965, https://doi.org/10.1016/j.jecp.2020.105068. (http://www.sciencedirect.com/science/article/pii/S0022096520305221)


Provided by Durham University

The Mind and the Body (Neuroscience)

Some people can literally feel their heart beating in their chest. This type of perceptive ability varies from one person to the next and has to do with our interoceptive sense, which helps us understand and feel what’s going on inside our body. Our body’s sensory cells generate a constant stream of information about the movements of our organs, the pressure in our vessels, our spatial orientation and, of course, our heartbeat. Millions of impulses rush to our brain 24/7, giving us a sense and awareness of our body, at least in part.

An increasing number of researchers today believe that internal body signals are the basis for the development of our sense of self. (Image: iStock / quickshooting)

An increasing number of scientists now believes that these internal signals are a prerequisite for developing the sense of self and self-consciousness that are the defining characteristics of the human species. “The experience of our consciousness depends on our body’s sensory signals,” says Bigna Lenggenhager, professor of cognitive neuropsychology at UZH, who researches the physical self and the development of self-perception.

Descartes’ Error

One of the pioneers in the field of body and consciousness is the US neuroscientist Antonio Damasio. In the 1990s, his book Descartes’ Error presented an evolutionary-biological theory on self-consciousness that contradicts the hypotheses of 16th-century philosopher and mathematician René Descartes. The French scholar saw the body and the mind as separate entities, with the tiny pineal gland as the principal seat of the soul and the place in which all our thoughts are formed.

According to Damasio, this dualist separation of mind and body is an error. In his book, he explains how the information on biochemical and physical body functions became more and more integrated as organisms developed. This ultimately led to the development of the brainstem, where an unconscious and rudimentary proto-self was generated. In the millions of years that followed, the Homo genus developed higher cognitive functions in the cortex above the brainstem, which enables us to reflect on and change our behavior. From this, our consciousness emerged, along with our language skills and memory. These abilities are located in multiple regions of the brain which work together and onto which the body’s sensory input is projected. “By integrating these signals, a coherent sense of self is created,” says Lenggenhager.

Break new ground

The neuropsychologist researches how changes in our bodily self-perception affect how we experience our self. Her aim is to better understand our self-consciousness, but she also wants to break new ground when it comes to treating people suffering from body dysmorphic disorders (BDD). People with BDD perceive some part of their body to be severely flawed. An extreme form of this disorder is xenomelia, where sufferers believe one or more of their limbs do not belong to their body.

It seems that our bodies and our consciousness are much closely linked than previously thought. Of course, external influences such as our social environment and family situation remain important factors. Likewise, psychoactive substances such as drugs can alter the biochemical processes in our brain and distort our self-perception.

Seat of our lifelong, conscious identity

As an object of perception, however, the body can deliver new insights and theories on some long-held mysteries, such as the sense of continuity of our personal identity, which has long been on the minds’ of consciousness researchers. Every day, we wake up and experience ourselves as one and the same person, for as long as we live. There is speculation that the uninterrupted stream of organ signals such as the heartbeat could be the foundation of our sense of self. The heart could then not only be considered our body’s engine, pumping oxygen into our system, but also the seat of our lifelong, conscious identity.

Provided by University of Zurich

Tubarial Glands: New Organ Discovered in Human Body (Biology)

Our body contains a pair of previously overlooked and clinically relevant nasopharyngeal salivary glands, according to new research led by the Netherlands Cancer Institute and the University of Amsterdam. Sparing these newly-identified glands, named the ‘tubarial glands,’ in patients receiving radiotherapy may provide an opportunity to improve their quality of life.

Researchers at the Netherlands Cancer Institute have discovered a new location of the salivary glands. This is potentially great news for patients with head and neck tumors: radiation oncologists will now be able to circumvent this area to avoid potential complications. On Friday October 16th they publish their research in Radiotherapy & Oncology, together with colleagues from Amsterdam UMC, UMCG and UMC Utrecht.

This illustration shows the location of the newly-identified tubarial glands. Image credit: Netherlands Cancer Institute.

You might expect that we would know all parts of our body by now. Advanced technology allows us to visualize organs, cells, and even molecules. What are the odds of a new discovery?

Unexpected

Imagine the surprise of radiation oncologist Wouter Vogel and oral and maxillofacial surgeon Matthijs Valstar who were studying a new type of scan as part of their research when they discovered that, all the way in the back of the nasopharynx, two unexpected areas had lit up. Areas that looked similar to known major salivary glands.

At the Netherlands Cancer Institute, Vogel and Valstar investigate the side effects radiation can have on the head and neck. The scans they studied, highlighted the salivary glands through the use of a marker, in order to spare them during treatment.

New areas

But there, all the way in the back of the nasopharynx, there shouldn’t be any large salivary glands, right? “People have three sets of large salivary glands, but not there,” Vogel explains. “As far as we knew, the only salivary or mucous glands in the nasopharynx are microscopically small, and up to 1000 are evenly spread out throughout the mucosa. So, imagine our surprise when we found these.”

In collaboration with their colleagues at UMC Utrecht, they discovered that all 100 people whose scans they studied had a set of these glands. These patients had a new type of scan done because of their prostate cancer: a PSMA PET/CT scan. Salivary glands show up rather clearly on this kind of imaging. Valstar: “The two new areas that lit up turned out to have other characteristics of salivary glands as well.” This was confirmed in the tissue of two human bodies they studied together with their colleagues at the Amsterdam UMC. “We call them tubarial glands, referring to their anatomical location.”

Trouble speaking

Back to the people for whom Valstar and Vogel initially started their research: patients with head and neck cancer, including tumors in the throat or tongue. “Radiation therapy can damage the salivary glands, which may lead to complications,” radiation therapist Vogel explains. “Patients may have trouble eating, swallowing, or speaking, which can be a real burden.”

Less complications

And yes, radiation of these ‘new’ glands can also go hand in hand with these complications. In collaboration with their colleagues at University Medical Center Groningen (UMCG), the researchers analyzed the data of 723 patients who had undergone radiation treatment. Their conclusion: the more radiation delivered to these new areas, the more complications the patients experienced afterwards. Just like what happens to the known salivary glands.

This means that the discovery is not only surprising, but it could also be a benefit to cancer patients. “For most patients, it should technically be possible to avoid delivering radiation to this newly discovered location of the salivary gland system in the same way we try to spare known glands,” Vogel concludes. “Our next step is to find out how we can best spare these new glands and in which patients. If we can do this, patients may experience less side effects which will benefit their overall quality of life after treatment.”

This research has been made possible through the financial support of The Dutch Cancer Society (KWF) and the Maarten van der Weijden Foundation.

References: Matthijs H. Valstar, Bernadette S. de Bakker, Roel J.H.M. Steenbakkers, Kees H. de Jong, Laura A. Smit, Thomas J.W. Klein Nulent, Robert J.J. van Es, Ingrid Hofland, Bart de Keizer, Bas Jasperse, Alfons J.M. Balm, Arjen van der Schaaf, Johannes A. Langendijk, Ludi E. Smeele, Wouter V. Vogel,
The tubarial salivary glands: A potential new organ at risk for radiotherapy,
Radiotherapy and Oncology,
2020, ISSN 0167-8140, doi:
https://doi.org/10.1016/j.radonc.2020.09.034.
(http://www.sciencedirect.com/science/article/pii/S0167814020308094)

Provided by Netherlands Cancer Institute

Targeting Our Second Brain To Fight Diabetes (Neuroscience)

Since 2004, Claude Knauf (INSERM) and Patrice Cani (UCLouvain) have been collaborating on molecular and cellular mechanisms in order to understand the causes of the development of type 2 diabetes and above all to identify new therapeutic targets. In 2013, they created an international laboratory, ‘NeuroMicrobiota Lab’ (INSERM-UCLouvain), to identify links between the brain and intestinal bacteria.

Patrice Cani (UCLouvain) and Claude Knauf (INSERM) have discovered a ‘jammer’ that blocks communication between the gut and the brain, thus preventing proper regulation of sugar and causing insulin resistance in people with diabetes. They also discovered that a lipid produced by our body helps prevent this dysfunction and regulate sugar level, thus mitigating diabetes and intestinal inflammation. These discoveries, published in the scientific journal GUT, are major, because today one in two Europeans is overweight and one in ten has diabetes. ©UCLouvain

Very quickly, they understood that the gut-brain axis plays a preponderant role in the regulation of sugar in the blood. When we eat, the gut (also called the ‘second brain’ owing to the neurons that compose it) contracts and digests food. Sugar and fat enter the body and their levels increase in the blood. Using this sugar and fat, the body then does its work or stores them. In a person with diabetes, this process malfunctions and the sugar level increases in abnormal proportions.

Taking a step further, the two researchers observed that the gut, when it digests, sends a signal to the brain, to find out what to do with the incoming fats and sugars. The brain then sends the message to various organs (liver, muscles, adipose tissue) to get ready to lower blood sugar and fat levels. In a diabetic individual, however, this mechanism doesn’t work. Researchers have observed that the gut malfunctions and sends no signal to the brain. The cause is hypercontractility of the intestine, which interferes with communication with the brain. Suddenly, commands to get the sugar out of the blood no longer pass. The sugar remains, causing hyperglycaemia. The mechanism also impacts the action of insulin: no message means no insulin action, resulting in insulin resistance.

The researchers sought to understand this hypercontractility, by observing the differences in the constitution of the intestine as well as the action of prebiotics within the microbiota in ‘normal’ and ‘diabetic’ mice. They observed that a particular lipid was severely deficient in diabetic mice, but also in people with diabetes (although it’s naturally present in the intestines of healthy patients). The team therefore tested the impact of the lipid on the use of sugars, on the contraction of the intestine and, ultimately, on diabetes. NeuroMicrobiota research team members Anne Abot and Eve Wemelle discovered the lipid is the key to restoring the use of sugar. It works by acting directly on the second brain.

Today, the team has discovered and understood how our gut bacteria (or gut microbiota) play an important role in altering the production of bioactive lipids, and from there to restore perfect communication between the gut and the brain. Hence some of these lipids are essential messengers which act on very precise targets in the second brain (enkephalins or opioid receptors). Treatment possibilities include modifying the body’s production of such lipids, could or taking them orally. These avenues are under study.

Using the same approach, the INSERM-UCLouvain research team, contributed to the discovery of a new bioactive lipid that reduces intestinal inflammation. It is directly produced by certain gut bacteria, also identified in this study and therefore the two approaches, either the lipid or one or more bacteria, could serve as a therapeutic target.

One in three of the 150,000 humans who die every day is a victim of cardiovascular disease, according to WHO. Half the Belgian population is overweight and presents cardiovascular and type 2 diabetes risks. This UCLouvain and INSERM research could potentially have an impact on a large portion of the population.

References: Abot A, Wemelle E, Laurens C, et al Identification of new enterosynes using prebiotics: roles of bioactive lipids and mu-opioid receptor signalling in humans and mice Gut Published Online First: 05 October 2020. doi: 10.1136/gutjnl-2019-320230 link: https://gut.bmj.com/content/early/2020/09/29/gutjnl-2019-320230

Provided by University Of Catholique De Louvain

New Discovery Helps Researchers Rethink Organoid Cultures (Medicine)

Organoids are stem cell-based tissue surrogates that can mimic the structure and function of organs, and they have become a key component of numerous types of medical research in recent years. But researchers from The University of Texas at Austin have uncovered problems with the conventional method for growing organoids for common experiments that may cause misleading results.

A look at an organoid sample, with different sizes based on their location in the culture. Credit: University of Texas at Austin

The researchers discovered that the size of organoids differ depending on where they are located within the hydrogel material called extracellular matrix (ECM) that is commonly used in biomedical research. The team found that organoids on the edges of a dome-shaped ECM respond differently to chemical or biological stimuli compared to those in the center of the dome.

This observation means one organoid in the core might react positively to a new treatment or drug, while another one on the edge could have a negative reaction, potentially muddying the results of an experiment. Ideally, organoids would be consistent in size and reaction in preclinical experiments.

“There are hundreds of organoids in the hydrogel dome, and they’re showing different sizes, different functions, and that can be problematic” said Woojung Shin, a postdoctoral fellow and recent Ph.D. graduate from the Cockrell School of Engineering’s Department of Biomedical Engineering, who discovered the problem. “You may get very different results from what would actually happen in the human body as a result.”

The findings were published recently in Cell Press’ iScience. The team includes researchers from the Biomimetic Microengineering Laboratory in the Cockrell School and the Livestrong Cancer Institutes of UT’s Dell Medical School.

The research began when Shin noticed that something felt off while examining organoids. They were slightly different sizes based on their location in the sample.

They repeated the experiment and identified the same issues time after time with different organoid lines. The team found morphogens in the culture medium — signaling molecules that are essential for organoid growth — that can spread and create a “gradient” within the hydrogel domes. One of the representative morphogens, Wnt3a, was extremely unstable. A computational simulation confirmed that the size difference in organoids is likely explained by the morphogen gradient and its instability.

The paper mainly focuses on the problem the researchers uncovered, but it also offers a roadmap for finding solutions. The key, the researchers say, is to stabilize the Wnt3a protein across the sample, reducing the size of the gradient created and, subsequently, the location-based differences in the organoids.

Woojung Shin, a postdoctoral fellow and recent Ph.D. graduate from the Cockrell School of Engineering’s Department of Biomedical Engineering and biomedical engineering assistant professor Hyun Jung Kim. Credit: The University of Texas at Austin

Shin is a member of biomedical engineering assistant professor Hyun Jung Kim’s research group. She focuses on disease modeling and bioinspired organ mimicry.

Organoids are an important part of the ongoing research conducted by Kim and his group. The team uses nature’s engineering principles, or biomimetic engineering, to solve the fundamental questions about human health and disease, most notably through its organ-on-a-chip technology.

Continuing to refine organoid research principles is key to the success of Kim’s group as well as a host of different types of medical research. The paper mentions disease modeling, tissue engineering, patient-specific validation of new drug candidates and research into the relationship between demographics and disease as areas that have benefitted from organoid research.

“We really want to have reproducible and reliable experimental results,” Kim said. “What we’ve found here is that we all need to be more cautious about how we interpret data, and then maybe we can decrease the risk of misinterpretation.”

References: Woojung Shin et al, Spatiotemporal Gradient and Instability of Wnt Induce Heterogeneous Growth and Differentiation of Human Intestinal Organoids, iScience (2020). DOI: 10.1016/j.isci.2020.101372 link: https://www.cell.com/iscience/fulltext/S2589-0042(20)30560-5?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2589004220305605%3Fshowall%3Dtrue

Provided by University of Texas at Austin

How Exactly Does Fever Help You Get Better? (Biology)

You’ve been dealing with sniffles and a sore throat for a day or so, hoping dearly that it’s just a minor bug, when bam! — you’re suddenly shivering, exhausted, and achy all over. You’ve got a fever. Before you go reaching for a fever-reducing drug, though, listen up: It might feel like death, but fever is often what your body needs to fight off that illness once and for all.

Fevers are such good infection fighters that species across the animal kingdom get them too. That includes everything from warm-blooded mammals like cats and dogs to cold-blooded species like lizards and fish, who move to a sunny rock or warmer water to raise their body temperature when they’re sick. But as common as they are, scientists haven’t known all that much about how fevers help you get better until recently.

The part that was best understood was how fevers start. When a virus or bacterium invades your cells, immune cells called macrophages come to your rescue by gobbling up the invader and cleaning up dead cells. They also let the rest of the body know what’s going down by sending out an alert via proteins called cytokines. These messengers travel up the body’s neural superhighway, known as the vagus nerve, making a beeline for both the brain’s pain center and the hypothalamus. That’s the brain region that controls not only temperature but hunger, thirst, sleepiness — all those other things that go haywire when you’re sick.

Once the hypothalamus knows the body is under attack, it sends out signals to stoke the fires of fever. But why? For a long time, people assumed that a higher body temperature makes it harder for bacteria and viruses to thrive, and eventually kills them off. That’s true, but it turns out to be a very small part of fever’s power.

Another soldier in the fight against infection is the lymphocyte or white blood cell. Once macrophages have begun battle, they present pieces of the invader proteins to T-lymphocytes, which use them to target and destroy infection. These cells get a big boost from toasty temperatures. In 2011, researchers found that when mice were injected with a virus then had their body temperatures raised by 2 degrees, their bodies produced more of a specific type of T-cell than those of the mice who stayed at a normal temperature.

In January, scientists got an even more detailed answer for why fever gives the immune system a boost: It helps more lymphocytes move to the area under attack. In order to get to their destination, lymphocytes have to move out of the lymph node, stick to the blood vessel, and then travel to the infection. Doing that sticking are molecules called integrins, which are expressed on the lymphocyte surface. Integrins are shaped kind of like balloons, with a large, sticky head and a skinny tail that burrows beneath the surface of the lymphocyte.

In a study published in the journal Immunity, researchers found that fever boosts an integrin-supercharging protein called heat shock protein 90 (Hsp 90) in T-lymphocytes. These bind to the integrin tail, sometimes two at a time, helping more integrins cluster on the surface of the lymphocyte and move it more efficiently to the area it’s needed most. The researchers found that this doesn’t just help T-lymphocytes, but all sorts of immune cells. Interestingly, Hsp-90 only kicked in at a temperature of 101.3 degrees Fahrenheit (38.5 degrees Celsius) — the kind of temp that would likely leave you bedridden for the day.

Fever is a valuable tool for keeping your body healthy, which is why you shouldn’t go too hard on the fever meds. Of course, if your fever is very high — 103 degrees Fahrenheit (39.4 Celsius) for adults, lower for children — you should consult a doctor, who may well tell you to take something to reduce it. But if not, maybe ride it out. Just know there’s a war going on inside you, and do what you can to help the good guys win.

“Money Can’t Buy Happiness”, Isn’t Always True (Psychology)

We all know the tired cliché: “Money can’t buy you happiness.” But when you compare a Hollywood billionaire to someone who just got evicted from their apartment, the phrase starts to lose its meaning. Clearly, there’s a certain amount of money that can mean the difference between happiness and misery. But what amount is that? In 2010, researchers decided to find out, and their answer was pretty interesting.

For their study, which was published in the journal PNAS, Daniel Kahneman and Angus Deacon differentiated between two types of happiness. The first they called emotional well-being, defined as a person’s day-to-day emotional experience — “the frequency and intensity of experiences of joy, stress, sadness, anger, and affection that make one’s life pleasant or unpleasant,” as the researchers put it. The second they called life evaluation, defined as the self-perception of one’s life as a whole.

To gauge people’s feelings on these two metrics, They analyzed 450,000 responses to the Gallup-Healthways Well-Being Index, which is a daily survey of U.S. residents conducted by the Gallup Organization. The survey asked questions about things like how they were feeling yesterday and how they see life as a whole, in addition to basic demographic information such as gender, age, and income. Questions about emotional experiences were things like “Did you feel stress during a lot of the day yesterday?” and “Did you smile or laugh a lot yesterday?” Life assessment, meanwhile, required people to imagine a ladder with numbered rungs — rung 0 at the bottom, representing the worst possible life, and rung 10 at the top, representing the best. The survey then asked, “On which step of the ladder would you say you personally feel you stand at this time?”

Here’s what they found: When it comes to emotional well-being, money certainly does buy happiness — but only to a point. The more money you make, the more your day-to-day happiness improves until you hit around $75,000 per year. After that, the improvement levels off. That means someone who makes $150,000 per year isn’t likely to have a significantly happier day than someone making $75k. But when it comes to life evaluation? That’s a whole different ballgame. No matter their income bracket, people who make more money have a more favorable evaluation of their own life as a whole. The study concluded that “high income buys life satisfaction but not happiness, and that low income is associated both with low life evaluation and low emotional well-being.”

Why is this? Kahneman and Deacon have some ideas. “Low income exacerbates the emotional pain associated with such misfortunes as divorce, ill health, and being alone,” they write. It could be that once you have enough to weather the storms that head your way, it doesn’t matter how much extra you make — your day-to-day life is pretty much stable. But, the researchers note, it’s generally recognized that overall life evaluation is tied to your level of education, which in turn is tied to your income. In that way, the fact that money can buy you a positive assessment of your life makes sense. Maybe it’s time we all asked for a raise.

What Happens To Your Body In A Year? (Biology)

A year is just a quick spin around the sun. A 365-day solar system lap. But in that stretch of time, a lot happens — in space, on Earth, and even inside your body. Your body is constantly at work to keep you alive and kickin’, and looking at all the ways your body changes in a single year is both surprising and cool as hell.

In a single year, you’ll lose about 4 kilograms (8.8 pounds) of skin cells and 27,000 hairs. But your body will also make a lot in one year: you’ll produce 3.5 centimeters (1.4 inches) of fingernails, 15 centimeters (5.9 inches) of hair, 73 trillion red blood cells, 1,400 liters (370 gallons) of sweat, 360 liters (95 gallons) of saliva and 80 liters (21 gallons) of tears. That’s one busy body.

The World Science Festival has information on more amazing (or gross, depending on your outlook) things your body does in a year: You’ll expel about 511 liters (135 gallons) of urine, your heart will beat 40 million times, and your blood will travel 7,048,928 km (4.38 million miles). So even on your most sluggish days on the couch, take comfort in the fact that your bod is still very hard at work. Thanks, body!