Scientists discover a new way to search for dark matter
Have we already found dark matter? It may be hiding in existing data, says a study.
- A new study proposes to look for dark matter during the process of scattering.
- The scientists think dark matter indicators could be hiding in existing data.
- The researchers aim to adapt current experiments to find the elusive particles.
Dark matter is famously supposed to take up 27% of the existing mass-energy of the universe. Dark energy eats up another 68%, while ordinary matter and energy that includes us accounts for just about 5%, scientists estimate. But if so much of everything is taken up by dark matter and dark energy, where are they? Neither has been conclusively detected, but a new study proposes a fresh way to spot dark matter signatures, looking in data we already gathered.
The study, led by researchers from the Lawrence Berkeley National Laboratory and UC Berkeley, found that it may be possible to detect dark matter signals during scattering. This process occurs when dark matter particles collide with atomic nuclei, producing small flashes of light and other potentially noticeable indicators. The scientists think they can pinpoint such moments and capture dark matter by looking for ejected electrons, neutrinos or other signs.
The study suggests that some currently existing experiments can be adapted to search for these kind of signals that relate to how the dark matter energy is absorbed.
The scientists also propose they can look through particle detector data that's already been gathered to find dark matter characteristics.
The study's lead author, postdoctoral researcher Jeff Dror from Berkeley Lab's Theory Group and UC Berkeley's Berkeley Center for Theoretical Physics, explained that "You can make a huge amount of progress with very little cost if you step back a little bit in the way we've been thinking about dark matter."
Photomultiplier tube arrays prepared for the LUX-ZEPLIN experiment. Sanford Underground Research Facility in Lead, South Dakota.
Credit: Matt Kapust/SURF
The researchers hope their approach can lead to new avenues in the search for the elusive dark matter. One plan is to focus on discovering light fermions, which may be related to the so-called "sterile neutrinos" – another theorized particle.
Most conducive to re-adapting, according to the scientists, would be existing experiments involving large, highly-sensitive detector materials with low background "noise" or interference. One such contraption could be the ultra sensitive UX-ZEPLIN (LZ), a dark matter search project currently under construction in a former South Dakota mine.
Another possibility is try the new method with the data from the Enriched Xenon Observatory (EXO), an underground experiment that already cooperated with the researchers.
"The data is already basically sitting there. It's just a matter of looking at it," Dror stated.
The scientists plan to explore various collaborations to tweak already running experiments.
Dror thinks finding out what dark matter is made of would be within future reach. "For me, that's a huge motivation to keep pushing—there is new physics out there," he added.
The study's co-authors included the UC Berkeley graduate student Robert McGehee, and Gilly Elor of the University of Washington.
Read the new study in Physical Review Letters.
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New research establishes an unexpected connection.
- A study provides further confirmation that a prolonged lack of sleep can result in early mortality.
- Surprisingly, the direct cause seems to be a buildup of Reactive Oxygen Species in the gut produced by sleeplessness.
- When the buildup is neutralized, a normal lifespan is restored.
We don't have to tell you what it feels like when you don't get enough sleep. A night or two of that can be miserable; long-term sleeplessness is out-and-out debilitating. Though we know from personal experience that we need sleep — our cognitive, metabolic, cardiovascular, and immune functioning depend on it — a lack of it does more than just make you feel like you want to die. It can actually kill you, according to study of rats published in 1989. But why?
A new study answers that question, and in an unexpected way. It appears that the sleeplessness/death connection has nothing to do with the brain or nervous system as many have assumed — it happens in your gut. Equally amazing, the study's authors were able to reverse the ill effects with antioxidants.
The study, from researchers at Harvard Medical School (HMS), is published in the journal Cell.
An unexpected culprit
The new research examines the mechanisms at play in sleep-deprived fruit flies and in mice — long-term sleep-deprivation experiments with humans are considered ethically iffy.
What the scientists found is that death from sleep deprivation is always preceded by a buildup of Reactive Oxygen Species (ROS) in the gut. These are not, as their name implies, living organisms. ROS are reactive molecules that are part of the immune system's response to invading microbes, and recent research suggests they're paradoxically key players in normal cell signal transduction and cell cycling as well. However, having an excess of ROS leads to oxidative stress, which is linked to "macromolecular damage and is implicated in various disease states such as atherosclerosis, diabetes, cancer, neurodegeneration, and aging." To prevent this, cellular defenses typically maintain a balance between ROS production and removal.
"We took an unbiased approach and searched throughout the body for indicators of damage from sleep deprivation," says senior study author Dragana Rogulja, admitting, "We were surprised to find it was the gut that plays a key role in causing death." The accumulation occurred in both sleep-deprived fruit flies and mice.
"Even more surprising," Rogulja recalls, "we found that premature death could be prevented. Each morning, we would all gather around to look at the flies, with disbelief to be honest. What we saw is that every time we could neutralize ROS in the gut, we could rescue the flies." Fruit flies given any of 11 antioxidant compounds — including melatonin, lipoic acid and NAD — that neutralize ROS buildups remained active and lived a normal length of time in spite of sleep deprivation. (The researchers note that these antioxidants did not extend the lifespans of non-sleep deprived control subjects.)
Image source: Tomasz Klejdysz/Shutterstock/Big Think
The study's tests were managed by co-first authors Alexandra Vaccaro and Yosef Kaplan Dor, both research fellows at HMS.
You may wonder how you compel a fruit fly to sleep, or for that matter, how you keep one awake. The researchers ascertained that fruit flies doze off in response to being shaken, and thus were the control subjects induced to snooze in their individual, warmed tubes. Each subject occupied its own 29 °C (84F) tube.
For their sleepless cohort, fruit flies were genetically manipulated to express a heat-sensitive protein in specific neurons. These neurons are known to suppress sleep, and did so — the fruit flies' activity levels, or lack thereof, were tracked using infrared beams.
Starting at Day 10 of sleep deprivation, fruit flies began dying, with all of them dead by Day 20. Control flies lived up to 40 days.
The scientists sought out markers that would indicate cell damage in their sleepless subjects. They saw no difference in brain tissue and elsewhere between the well-rested and sleep-deprived fruit flies, with the exception of one fruit fly.
However, in the guts of sleep-deprived fruit flies was a massive accumulation of ROS, which peaked around Day 10. Says Vaccaro, "We found that sleep-deprived flies were dying at the same pace, every time, and when we looked at markers of cell damage and death, the one tissue that really stood out was the gut." She adds, "I remember when we did the first experiment, you could immediately tell under the microscope that there was a striking difference. That almost never happens in lab research."
The experiments were repeated with mice who were gently kept awake for five days. Again, ROS built up over time in their small and large intestines but nowhere else.
As noted above, the administering of antioxidants alleviated the effect of the ROS buildup. In addition, flies that were modified to overproduce gut antioxidant enzymes were found to be immune to the damaging effects of sleep deprivation.
The research leaves some important questions unanswered. Says Kaplan Dor, "We still don't know why sleep loss causes ROS accumulation in the gut, and why this is lethal." He hypothesizes, "Sleep deprivation could directly affect the gut, but the trigger may also originate in the brain. Similarly, death could be due to damage in the gut or because high levels of ROS have systemic effects, or some combination of these."
The HMS researchers are now investigating the chemical pathways by which sleep-deprivation triggers the ROS buildup, and the means by which the ROS wreak cell havoc.
"We need to understand the biology of how sleep deprivation damages the body so that we can find ways to prevent this harm," says Rogulja.
Referring to the value of this study to humans, she notes,"So many of us are chronically sleep deprived. Even if we know staying up late every night is bad, we still do it. We believe we've identified a central issue that, when eliminated, allows for survival without sleep, at least in fruit flies."
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