Illustration of the Johnson & Johnson coronavirus vaccine
Given Ruvic | Reuters
An advisory panel to the Centers for Disease Control and Prevention unanimously voted on Sunday to recommend the use of Johnson & Johnson’s one-off Covid-19 vaccine for those ages 18 and older as the federal government prepares to serve millions of doses this week to send .
As soon as CDC director Dr. Rochelle Walensky accepts the recommendation of the Advisory Committee on Immunization Practices, the federal government can begin shipping doses to locations across the country. The ACIP met in an emergency meeting to review the vaccine dates, which took place on Saturdaybecame the third shot to receive emergency clearance from the Food and Drug Administration.
Walensky said Friday that she “would be ready to review the ACIP recommendation” and “be ready to sign”.
“We are very close to having another vaccine in our tool boxes, the Johnson & Johnson Covid-19 Vaccine. Like many of you, I am pleased to hear that another safe and effective vaccine option could be coming as soon as next week “She said Friday. “An additional safe and effective vaccine will help protect more people, faster.”
Dr. Richard Nettles, vice president of medical affairs at J&J, told lawmakers Tuesday that the company was ready to ship nearly 4 million doses once it receives emergency approval. He added that the company expects to have 20 million cans ready by the end of March.
The introduction of the J&J shot could be a boon to the U.S. vaccine supply. While the new vaccine showed signs of being less effective at preventing Covid-19 in clinical trials when compared to Pfizer-BioNTech and Moderna vaccines, the J&J shot was 100% effective at preventing deaths and hospitalizations, caused by Covid-19 in clinical trials.
The level of protection of the J&J vaccine against Covid-19 in studies varied regionally, according to FDA documents released on Wednesday. About a month after inoculation, the shot showed 72% effectiveness in the US, 61% in Latin America and 64% in South Africa, where variant B.1.351 is spreading rapidly.
In particular, the FDA review found the vaccine was significantly less effective in people aged 60 and over who also had comorbidities like diabetes or heart disease. However, the agency found that the data was too sparse for any conclusions to be drawn.
In contrast, in clinical studies, Pfizer’s vaccine has been found to be 95% effective against Covid-19, while Moderna’s vaccine is around 94% effective. Infectious disease experts pointed out that J & J’s numbers cannot be used as a head-to-head comparison with the other two vaccines because it is a single dose and the company’s study was conducted when more infections, as well as new, more contagious variants occurred.
However, federal health officials have indicated that the one-off J&J regime offers unique logistical benefits that could make it ideal for hard-to-reach populations.
J & J’s vaccine “makes it easier to use in many contexts,” said Dr. Nancy Messonnier, director of the National Center for Immunization and Respiratory Diseases of the CDC, told the Journal of the American Medical Association during a question and answer session Friday. “I suspect that much of the national health consideration given to these vaccines is more about the ease of use of the J&J vaccine and how it might be better suited to some populations.”
J&J has announced that it will ship the vaccine, which contains five doses per vial, at 36 to 46 degrees Fahrenheit. In comparison, Pfizer’s vaccine typically has to be stored in ultra-cold freezers, which are between minus 112 and minus 76 degrees Fahrenheit. However, the FDA recently announced that it could be stored in pharmacies for up to two weeks at standard freezing temperatures. Moderna vaccine must be shipped at 13 to 5 degrees above zero Fahrenheit.
– CNBC’s Berkeley Lovelace contributed to this report.
#Roommates, Eve and Naturi Naughton are preparing to star in a new drama pilot that will give fans a nostalgic look at hip hop in the ’90s. The two women have just been confirmed to star in the hip hop drama “Queens”, which is about four friends who were once part of a female superstar rap group.
According to @Deadline, Eve and Naturi Naughton are bringing it back to their musical roots with the announcement of a drama pilot for ABC. “Queens” is the latest hip hop musical television series, following shows such as “Empire” and “Wu-Tang: An American Saga”. The series was written by Zahir McGhee and is about four estranged former group members in their forties who reunite to regain their musical fame as “Nasty B ** ches” – their 90s group that made them legends in the hip Hops world.
Naturi will play Jill, aka Da Thrill, a founding member of Nasty B ** ches. She used to be known for her legendary rhymes and nasty drug habits. These days, Jill lives a quiet life as a devout Catholic with her husband. In the meantime, Eve will play another member of the group named Brianna. However, the specific details about her character have not yet been released.
The project marks Eve’s official return to screenwriting television after her self-titled comedy series “Eve” in the mid-2000s, when she recently left her co-hosting appearance on CBS’s “The Talk”. Naturi can be seen every week in the Starz spin-off series ‘Power Book II: Ghost’, in which she repeats her role as Tasha St. Patrick.
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On October 19th, 2017, astronomers from the Haleakala Observatory in Hawaii announced the first-ever detection of an interstellar object in our Solar System. In honor of the observatory that first spotted it, this object (designated 1I/2017 U1) was officially named ‘Oumuamua by the IAU – a Hawaiian term loosely translated as “Scout” (or, “a messenger from afar arriving first.”)
Multiple follow-up observations were made as ‘Oumuamua left our Solar System and countless research studies resulted. For the most part, these studies addressed the mystery of what ‘Oumuamua truly was: a comet, an asteroid, or something else entirely? Into this debate, Dr. Shmuel Bialy and Prof. Avi Loeb of the Harvard Institute for Theory and Computation (ITC) argued that ‘Oumuamua could have been an extraterrestrial probe!
Having spent the past few years presenting this controversial theory before the scientific and astronomical community, Prof. Loeb has since shared the story of how he came to it in his new book, Extraterrestrial: The First Sign of Intelligent Life Beyond Earth. The book is a seminal read, addresses the mystery of ‘Oumuamua, and (most importantly) urges readers to take seriously the possibility that an extraterrestrial encounter took place
Credit: Houghton Mifflin Harcourt
To break it down succinctly, Prof. Loeb expands on an argument he made roughly three years ago about the first interstellar object ever to be observed in our Solar System. Beyond reiterating the evidence, however, Loeb also takes the time to share personal stories and relate how his upbringing and experiences over the years led him down the path that culminated in this controversial theory.
These include his formative years in Israel, his lifelong love of philosophy and the big questions – i.e., “Why are we here?” “How did it all begin?” “How will it end?” and “are we alone in the Universe?” – and how an aptitude for math and science eventually led brought him to astrophysics. But as he relates, it was the way astrophysics is also concerned with the big questions in life (but also attempts to answer them) that to become a leading figure in the field.
After looking at all the evidence ‘Oumuamua provided during the 11 days we were able to observe it, Loeb (and co-author Dr. Bialy) concluded that the possibility that happened to fit all of the facts (limited though they were) was the same one scientists were not likely to take seriously (at least at first). In the end, Loeb presents his case for an interstellar messenger in a way that is simple, poignant, and not difficult at all to follow.
While some technical knowledge is certainly helpful to appreciate this book, it is by no means a prerequisite. Like any science communicator worth his salt, Loeb is able to relate scientific findings in a way that is accessible. But like any truly great science communicator, in the mold of Carl Sagan, he manages to convey it all in a way that is both inspired and inspiring.
‘Oumuamua as it appeared using the William Herschel Telescope on the night of October 29. Queen’s University Belfast/William Herschel Telescope
Interstellar Messenger
To recap, the story of ‘Oumuamua’s visit began when the Panoramic Survey Telescope and Rapid Response System-1 (Pan-STARRS-1), located at the Haleakala Observatory in Hawaii, announced the first-ever detection of an interstellar object passing by Earth. Based on the available data, astronomers concluded that the object entered the orbital plane of the Solar System on Sept. 6th and made its closest pass to the Sun (perihelion) on Sept. 9th.
On October 7th, it flew past Earth on its way out of the outer Solar System towards the Pegasus constellation. The object was only visible to Earth-based instruments for a total of 11 days, but what the observations revealed in this amount of time was quite fascinating – not to mention confounding. For starters, the images captured by Pan-STARRS-1 implied that ‘Oumuamua was either a highly elongated body, or pancake-shaped.
‘Oumuamua also appeared to be spinning rapidly and have a high density, which is indicative of a rocky and metallic composition (i.e., an asteroid). But when it made its closest pass to the Sun, it did not form a tail (as is customary with comets). Nevertheless, spectral and thermal imaging showed that ‘Oumuamua was rather bright and reflective, which consistent with ice.
As ‘Oumuamua began to leave the Solar System, the Hubble Space Telescope snapped some final images that showed the object increasing in velocity. The most obvious explanation for this was that ‘Oumuamua was venting material from its surface due to solar heating (aka. outgassing), which is again consistent with a comet. However, as Bialy and Loeb pointed out, there would be evidence of this that would be impossible to ignore.
Artist’s impression of the first interstellar asteroid/comet, “Oumuamua”. This unique object was discovered on 19 October 2017 by the Pan-STARRS 1 telescope in Hawaii. Credit: ESO/M. Kornmesser
For starters, there was the fact that it had formed no tail when it made its closest pass to our Sun. In addition, the sudden acceleration could not be attributed to gravitational forces since these should have been slowing ‘Oumuamua down at the time. And last, outgassing would have caused a rapid change in ‘Oumuamua’s spin (causing it to become more violent) which was also not observed.
According to Loeb and Bialy, the only thing that could be confirmed was that radiation pressure was the likeliest cause for the increase in velocity. But if ‘Oumuamua was neither a comet nor an asteroid, what could it be? Moreover, what could account for all of its strange behavior? Here too, scientists could only say with confidence that it was unlike any object we’ve ever seen before.
A Bold Theory
As we addressed at the time, Dr. Shmuel Bialy and Prof. Avi Loeb originally proposed their theory in October 2018 in a study titled “Could Solar Radiation Pressure Explain ‘Oumuamua’s Peculiar Acceleration?” The study was peer-reviewed and accepted for publication in The Astrophysical Journal Letters shortly thereafter, and was met with a mix of reactions.
Citing a number of lines of evidence, the two ventured that ‘Oumuamua’s anomalous nature could be explained in the following way: its pancake-like profile and highly-reflective nature were both consistent with a light sail. Its sudden acceleration and deviation from its expected orbit were consistent with radiation pressure interacting with a light sail, and the way it entered our Solar System was what one might expect of an interstellar explorer.
Diagram showing the trajectory of ‘Oumuamua from early August to late October of 2018. Credit: SETI Institute
Naturally, this claim generated quite a bit of controversy. On the one side, there was the predictable response where various media claimed that Prof. Loeb and his colleague were claiming, “IT WAS ALIENS!” On the other side, there were those who scoffed at the very notion that a highly-accredited scientist with Loeb’s reputation would argue something so “unscientific.”
And yet, Loeb not only maintained this argument over time, but he has since released a book that addressed his controversial theory and the path that led him to it. Titled, Extraterrestrial: The First Sign of Intelligent Life Beyond Earth, Loeb makes a more concerted and human appeal to the scientific community and general public, urging them to seriously consider the possibility that ‘Oumuamua was an alien messenger.
Technosignatures
As Loeb indicates in the book, this theory was partly inspired by his work with Project Starshot, a program for interstellar exploration sponsored by Breakthrough Initiatives. Beginning in 2015, Loeb and his colleagues at the Harvard Smithsonian Center for Astrophysics (CfA) worked to design a spacecraft capable of reaching the Alpha Centauri system in our lifetimes and report on what is there.
After much consideration, they realized that a lightsail pushed by a 100 gigawatt-laser was the best way to achieve relativistic speeds (a significant fraction of the speed of light). They further concluded that the spacecraft would have to be about the size and mass of a mobile phone. Given all of the advancements in recent years in terms of electronics and digital technology, they determined this was entirely feasible.
Artist’s impression of the interstellar object, `Oumuamua, experiencing outgassing as it leaves our Solar System. Credit: ESA/Hubble/NASA/ESO, M. Kornmesser
With the help of Prof. Philip Lubin of UCSB, an expert in directed-energy propulsion and applications, the concept came together to yield Starshot – a lightsail and a Starchip spacecraft. Another result of this project was the way it inspired Loeb and other scientists to suggest that SETI researchers should look for optical signals (lasers), which could be signs of alien communications or propulsion systems.
In this respect, says Loeb, ‘Oumuamua arrived at a time when Starshot was still fresh in his mind and (between its peculiar characteristics and behavior) the pieces fell into place. It was here, Loeb writes, that he asked Dr. Bialy to join him in testing the hypothesis:
“To be clear, my attitude at the time was simply That might work. The astronomical world had been presented with an exciting discovery, an interstellar object, about which we had collected a trove of confounding data. We confronted facts that were hard to match to a hypothesis that accounted for all of them. When I proposed that Bialy and I explain ‘Oumuamua’s deviation by way of sunlight, I was following the same scientific tenet I had always followed – a hypothesis that satisfied all the data ought to be considered.”
It was only after they checked the numbers, and confirmed that they worked, that the interstellar probe theory really began to form. The next step was to compute what an interstellar probe would look like in terms of size and composition, thickness, and reflectivity. In the end, all of the evidence proved to be consistent. As Loeb explained it, it all rested on the notion that ‘Oumuamua wasn’t natural in origin:
“The lightsail inference may seem outlandish,” Loeb summarized, “but getting to it did not require any wild leaps. Shmuel and I went down a logical path. We followed the evidence, and, in the grand tradition of the detective work of science, we hewed closely to a maxim of Sherlock Holmes: “When you have eliminated the impossible, whatever remains, however improbable, must be the truth.” Hence our hypothesis: ‘Oumuamua was artificial.”
Artist’s concept for the Breakthrough Starshot spacecraft. Credit: Breakthrough Initiatives
Another important aspect of Loeb’s hypothesis involves a concept known as the Copernican Principle, which takes its name from Nicolaus Copernicus – the famed 16th-century Polish astronomer who developed the first complete heliocentric theory of the Universe. This principle essentially argues that Earth (and humanity, by extension) is not in a unique and privileged position to view the Universe.
Extended to the cosmological realm (where it’s also referred to as the Cosmological Principle), it asserts that habitable planets like Earth are likely to be representative of the norm, and are therefore not special. While this principle sounds more like philosophy than science, it provides SETI researchers for establishing parameters (much like the Drake Equation).
This also raises the issue of the Fermi Paradox, which expresses the disparity between the (assumed) statistical likelihood of extraterrestrial life and the apparent lack of evidence for it. Given the expanse of the cosmos, the number of stars and planets, and the fact that the ingredients for life are present everywhere in abundance, is it really so hard to consider that an advanced species has sent out probes to answer the big question?
And is it really so farfetched, when no alternative explanation is able to account for all the evidence, that ‘Oumuamua was one such probe? Like the possibility that it was an extraterrestrial lightsail, these questions cannot be answered just yet. Maybe someday, but in the meantime, they are vital food for thought.
An artist’s illustration of a light-sail powered by a radio beam (red) generated on the surface of a planet. Credit: M. Weiss/CfA
A Grand Tradition
“Extraordinary claims require extraordinary evidence.” These words were made famous by famed astronomer and science communicator Carl Sagan. In truth, he was paraphrasing Laplace’s principle, which states “the weight of evidence for an extraordinary claim must be proportioned to its strangeness.” You have to admit, Sagan’s version sounds better!
And there’s also the famous axiom of Sir Arthur Conan Doyle, which I need not repeat since Prof. Loeb beat me to it (well played, sir!). These words, which emphasize the need to eliminate the answers that don’t work in order to find the one that does, manages to capture the essence of deductive reasoning – a concept articulated by Renee Descartes.
Readers of Prof. Loeb’s work can certainly be forgiven for treating his arguments with skepticism, and he would surely be the first to recommend they do. But to reject this hypothesis without considering the arguments presented – or to label it as wistful, unscientific, or “the stuff of fantasy” – would represent a failure of both the empirical tradition and imagination.
Through his examination of the limited evidence we have on ‘Oumuamua and the application of the Copernican Principle, Loeb manages to make the case for a possible interstellar lightsail quite effectively. While we will never know for certain if ‘Oumuamua was an interstellar probe or not, it’s certainly worth considering what the implications of that would be.
One implication, as Prof. Loeb and Dr. Manasavi Lingham (also a researcher with the ITC) demonstrated in a subsequent study, is that our Solar System has likely captured thousands of interstellar objects over its lifetime. In yet another study, Prof. Loeb and Dr. Bialy surveyed known objects in the Solar System and identified several possible captured objects for future missions to study.
These and other hypotheses were validated less than two years after ‘Oumuamua was encountered when astronomers detected another “visitor” to our Solar System – the interstellar comet known as C/2019 Q4 (Borisov). Because of this, there are several proposals under consideration for sending a mission to rendezvous with an interstellar object in the future, like the ESA’s Comet Interceptor, Project Lyra, and others.
And as Prof. Loeb and Harvard astrophysicist Amir Siraj showed with more than one paper on the subject, we stand a much better chance of detecting these objects in the future. With the Vera C. Rubin Observatory, formerly known as the Large Synoptic Survey Telescope (LSST), astronomers will be able to detect a handful of interstellar objects a month – as part of the observatory’s Legacy Survey of Space and Time (LSST).
So while Fermi’s Paradox (i.e. “Where is everybody?”) has not been resolved (yet), it can certainly be argued that we are closed to it than ever before. No one can ever say with certainty how and when a first contact situation will occur (assuming it hasn’t already). But we can confidently say that if an extraterrestrial probe comes through our system in the future, we stand a far better chance of spotting and identifying it!
To learn more about Prof. Loeb’s work, to check out his book, or to have a gander at the many papers and works he has published over the years, check out his CfA webpage here! And be sure to check out our series that takes a look at the unresolved questions Search for Extraterrestrial Intelligence (SETI) titled, Beyond Fermi Paradox as well!
NEW YORK – Brooklyn Nets’ Kevin Durant will continue to serve as the NBA All-Star Game captain despite a hamstring injury preventing him from playing.
Durant and his all-star game captain LeBron James of the Los Angeles Lakers will each draw up a list of selected all-stars from the pool. The All-Star Draft will air on March 4th on TNT.
It remained unclear whether Durant will travel to Atlanta for the game on March 7th.
Durant has missed the Nets’ last seven games with a thigh strain and was excluded from the All-Star hiatus. NBA commissioner Adam Silver named Domantas Sabonis as Durant’s in-game replacement, and Jayson Tatum was named an All-Star Starter in Durant’s absence.
Durant is an 11-time All-Star, averaging 29 points, 7.3 rebounds and 5.3 assists for Brooklyn this season.
Every day, digital advertisement agencies serve billions of ads on news websites, search engines, social media networks, video streaming websites, and other platforms. And they all want to answer the same question: Which of the many ads they have in their catalog is more likely to appeal to a certain viewer? Finding the right answer to this question can have a huge impact on revenue when you are dealing with hundreds of websites, thousands of ads, and millions of visitors.
Fortunately (for the ad agencies, at least),reinforcement learning, the branch of artificial intelligence that has become renowned formastering board and video games, provides a solution. Reinforcement learning models seek to maximize rewards. In the case of online ads, the RL model will try to find the ad that users are more likely to click on.
The digital ad industry generates hundreds of billions of dollars every year and provides an interesting case study of the powers of reinforcement learning.
Naïve A/B/n testing
To better understand how reinforcement learning optimizes ads, consider a very simple scenario: You’re the owner of a news website. To pay for the costs of hosting and staff, you have entered a contract with a company to run their ads on your website. The company has provided you with five different ads and will pay you one dollar every time a visitor clicks on one of the ads.
Your first goal is to find the ad that generates the most clicks. In advertising lingo, you will want to maximize your click-trhough rate (CTR). The CTR is ratio of clicks over number of ads displayed, also called impressions. For instance, if 1,000 ad impressions earn you three clicks, your CTR will be 3 / 1000 = 0.003 or 0.3%.
Before we solve the problem with reinforcement learning, let’s discuss A/B testing, the standard technique for comparing the performance of two competing solutions (A and B) such as different webpage layouts, product recommendations, or ads. When you’re dealing with more than two alternatives, it is called A/B/n testing.
[Read: How do you build a pet-friendly gadget? We asked experts and animal owners]
In A/B/n testing, the experiment’s subjects are randomly divided into separate groups and each is provided with one of the available solutions. In our case, this means that we will randomly show one of the five ads to each new visitor of our website and evaluate the results.
Say we run our A/B/n test for 100,000 iterations, roughly 20,000 impressions per ad. Here are the clicks-over-impression ratio of our ads:
Ad 1: 80/20,000 = 0.40% CTR
Ad 2: 70/20,000 = 0.35% CTR
Ad 3: 90/20,000 = 0.45% CTR
Ad 4: 62/20,000 = 0.31% CTR
Ad 5: 50/20,000 = 0.25% CTR
Our 100,000 ad impressions generated $352 in revenue with an average CTR of 0.35%. More importantly, we found out that ad number 3 performs better than the others, and we will continue to use that one for the rest of our viewers. With the worst performing ad (ad number 2), our revenue would have been $250. With the best performing ad (ad number 3), our revenue would have been $450. So, our A/B/n test provided us with the average of the minimum and maximum revenue and yielded the very valuable knowledge of the CTR rates we sought.
Digital ads have very low conversion rates. In our example, there’s a subtle 0.2% difference between our best- and worst-performing ads. But this difference can have a significant impact on scale. At 1,000 impressions, ad number 3 will generate an extra $2 in comparison to ad number 5. At a million impressions, this difference will become $2,000. When you’re running billions of ads, a subtle 0.2% can have a huge impact on revenue.
Therefore, finding these subtle differences is very important in ad optimization. The problem with A/B/n testing is that it is not very efficient at finding these differences. It treats all ads equally and you need to run each ad tens of thousands of times until you discover their differences at a reliable confidence level. This can result in lost revenue, especially when you have a larger catalog of ads.
Another problem with classic A/B/n testing is that it is static. Once you find the optimal ad, you will have to stick to it. If the environment changes due to a new factor (seasonality, news trends, etc.) and causes one of the other ads to have a potentially higher CTR, you won’t find out unless you run the A/B/n test all over again.
What if we could change A/B/n testing to make it more efficient and dynamic?
This is where reinforcement learning comes into play. A reinforcement learning agent starts by knowing nothing about its environment’s actions, rewards, and penalties. The agent must find a way to maximize its rewards.
In our case, the RL agent’s actions are one of five ads to display. The RL agent will receive a reward point every time a user clicks on an ad. It must find a way to maximize ad clicks.
The multi-armed bandit
The multi-armed bandit must find ways to discover one of several solutions through trial and error
In some reinforcement learning environments, actions are evaluated in sequences. For instance, in video games, you must perform a series of actions to reach the reward, which is finishing a level or winning a match. But when serving ads, the outcome of every ad impression is evaluated independently; it is a single-step environment.
To solve the ad optimization problem, we’ll use a “multi-armed bandit” (MAB), a reinforcement learning algorithm that is suited for single-step reinforcement learning. The name of the multi-armed bandit comes from an imaginary scenario in which a gambler is standing at a row of slot machines. The gambler knows that the machines have different win rates, but he doesn’t know which one provides the highest reward.
If he sticks to one machine, he might lose the chance of selecting the machine with the highest win rate. Therefore, the gambler must find an efficient way to discover the machine with the highest reward without using up too much of his tokens.
Ad optimization is a typical example of a multi-armed bandit problem. In this case, the reinforcement learning agent must find a way to discover the ad with the highest CTR without wasting too many valuable ad impressions on inefficient ads.
Exploration vs exploitation
One of the problems every reinforcement learning model faces is the “exploration vs exploitation” challenge. Exploitation means sticking to the best solution the RL agent has so far found. Exploration means trying other solutions in hopes of landing on one that is better than the current optimal solution.
In the context of ad selection, the reinforcement learning agent must decide between choosing the best-performing ad and exploring other options.
One solution to the exploitation-exploration problem is the “epsilon-greedy” (ε-greedy) algorithm. In this case, the reinforcement learning model will choose the best solution most of the time, and in a specified percent of cases (the epsilon factor) it will choose one of the ads at random.
Every reinforcement learning algorithm must find the right balance between exploiting optimal solutions and exploring new options
Here’s how it works in practice. Say we have an epsilon-greedy MAB agent with the ε factor set to 0.2. This means that the agent chooses the best-performing ad 80% of the time and explores other options 20% of the time.
The reinforcement learning model starts without knowing which of the ads performs better, therefore it assigns each of them an equal value. When all ads are equal, it will choose one of them at random each time it wants to serve an ad.
After serving 200 ads (40 impressions per ad), a user clicks on ad number 4. The agent adjusts the CTR of the ads as follows:
Ad 1: 0/40 = 0.0%
Ad 2: 0/40 = 0.0%
Ad 3: 0/40 = 0.0%
Ad 4: 1/40 = 2.5%
Ad 5: 0/40 = 0.0%
Now, the agent thinks that ad number 4 is the top-performing ad. For every new ad impression, it will pick a random number between 0 and 1. If the number is above 0.2 (the ε factor), it will choose ad number 4. If it’s below 0.2, it will choose one of the other ads at random.
Now, our agent runs 200 other ad impressions before another user clicks on an ad, this time on ad number 3. Note that of these 200 impressions, 160 belong to ad number 4, because it was the optimal ad. The rest are equally divided between the other ads. Our new CTR values are as follows:
Ad 1: 0/50 = 0.0%
Ad 2: 0/50 = 0.0%
Ad 3: 1/50 = 2.0%
Ad 4: 1/200 = 0.5%
Ad 5: 0/50 = 0.0%
Now the optimal ad becomes ad number 3. It will get 80% of the ad impressions. Let’s say after another 100 impressions (80 for ad number three, four for each of the other ads), someone clicks on ad number 2. Here’s how what the new CTR distribution looks like:
Ad 1: 0/54 = 0.0%
Ad 2: 1/54 = 1.8%
Ad 3: 1/130 = 0.7%
Ad 4: 1/204 = 0.49%
Ad 5: 0/54 = 0.0%
Now, ad number 2 is the optimal solution. As we serve more ads, the CTRs will reflect the real value of each ad. The best ad will get the lion’s share of the impressions, but the agent will continue to explore other options. Therefore, if the environment changes and users start to show more positive reactions to a certain ad, the RL agent can discover it.
After running 100,000 ads, our distribution can look something like the following:
Ad 1: 123/30,600 = 0.40% CTR
Ad 2: 67/18,900 = 0.35% CTR
Ad 3: 187/41,400 = 0.45% CTR
Ad 4: 35/11,300 = 0.31% CTR
Ad 5: 15/5,800 = 0.26% CTR
With the ε-greedy algorithm, we were able to increase our revenue from $352 to $426 on 100,000 ad impressions and an average CTR of 0.42%. This is a great improvement over the classic A/B/n testing model.
Improving the ε-greedy algorithm
The key to the ε-greedy reinforcement learning algorithm is adjusting the epsilon factor. If you set it too low, it will exploit the ad which it thinks is optimal at the expense of not finding a possibly better solution. For instance, in the example we explored above, ad number four happens to generate the first click, but in the long run, it doesn’t have the highest CTR. Small sample sizes do not necessarily represent true distributions.
On the other hand, if you set the epsilon factor too high, your RL agent will waste too many resources exploring non-optimal solutions.
One way you can improve the epsilon-greedy algorithm is by defining a dynamic policy. When the MAB model is fresh, you can start with a high epsilon value to do more exploration and less exploitation. As your model serves more ads and gets a better estimate of the value of each solution, it can gradually reduce the epsilon value until it reaches a threshold value.
In the context of our ad-optimization problem, we can start with an epsilon value of 0.5 and reduce it by 0.01 after every 1,000 ad impressions until it reaches 0.1.
Another way to improve our multi-armed bandit is to put more weight on new observations and gradually reduces the value of older observations. This is especially useful in dynamic environments such as digital ads and product recommendations, where the value of solutions can change over time.
Here’s a very simple way you can do this. The classic way to update the CTR after serving an ad is as follows:
(result + past_results) / impressions
Here,resultis the outcome of the ad displayed (1 if clicked, 0 if not clicked),past_resultsis the cumulative number of clicks the ad has garnered so far, andimpressionsis the total number of times the ad has been served.
To gradually fade old results, we add a new alphafactor (between 0 and 1), and make the following change:
(result + past_results * alpha) / impressions
This small change will give more weight to new observations. Therefore, if you have two competing ads that have an equal number of clicks and impressions, the ones whose clicks are more recent will be favored by your reinforcement learning model. Also, if an ad had a very high CTR rate in the past but has become unresponsive in recent times, its value will decline faster in this model, forcing the RL model to move to other alternatives earlier and waste fewer resources on the inefficient ad.
Adding context to the reinforcement learning model
Contextual bandits use function approximation to factor in the individual characteristics of ad viewers
In the age of internet, websites, social media, and mobile apps haveplenty of information on every single user such as their geographic location, device type, and the exact time of day they’re viewing the ad. Social media companies have even more information about their users, including age and gender, friends and family, the type of content they have shared in the past, the type of posts they liked or clicked on in the past, and more.
This rich information gives these companies the opportunity to personalize ads for each viewer. But the multi-armed bandit model we created in the previous section shows the same ad to everyone and doesn’t take the specific characteristic of each viewer into account. What if we wanted to add context to our multi-armed bandit?
One solution is to create several multi-armed bandits, each for a specific sub-field of users. For instance, we can create separate RL models for users in North America, Europe, Middle East, Asia, Africa, and so on. What if we wanted to also factor in gender? Then we would have one reinforcement learning model for female users in North America, one for male users in North America, one for female users in Europe, male users in Europe, etc. Now, add age ranges and device types, and you can see that it will quickly develop into a big problem, creating an explosion of multi-armed bandits that become hard to train and maintain.
An alternative solution is to use a “contextual bandit,” an upgraded version of the multi-armed bandit that takes contextual information into account. Instead of creating a separate MAB for each combination of characteristics, the contextual bandit uses “function approximation,” which tries to model the performance of each solution based on a set of input factors.
Without going too much into the details (that could be the subject of another post), our contextual bandit usessupervised machine learning to predict the performance of each ad based on location, device type, gender, age, etc. The benefit of the contextual bandit is that it uses one machine learning model per ad instead of creating a MAB per combination of characteristics.
This wraps up our discussion of ad optimization with reinforcement learning. The same reinforcement learning techniques can be used to solve many other problems, such as content and product recommendation or dynamic pricing, and are used in other domains such as health care, investment, and network management.
This article was originally published by Ben Dickson on TechTalks, a publication that examines trends in technology, how they affect the way we live and do business, and the problems they solve. But we also discuss the evil side of technology, the darker implications of new tech and what we need to look out for. You can read the original article here.
The U.S. Food and Drug Administration has approved the use of the Johnson & Johnson coronavirus vaccine in adults. Maureen Ferran, a virologist at Rochester Institute of Technology, explains how this third approved vaccine works and examines the differences between it and the moderna and Pfizer-BioNTech vaccines already in use.
1. How does the Johnson & Johnson vaccine work?
The Johnson & Johnson vaccine is a so-called viral vector vaccine.
To make this vaccine, the Johnson & Johnson team took a harmless adenovirus – the viral vector – and replaced a small portion of its genetic instructions with coronavirus genes for the SARS-CoV-2 spike protein.
After this modified adenovirus is injected into a person’s arm, it enters the person’s cells. The cells then read the genetic instructions necessary to make the spike protein, and the vaccinated cells make the spike protein and display it on their own surface. The person’s immune system then notices these foreign proteins and makes antibodies against them that protect the person in the event that they are ever exposed to SARS-CoV-2 in the future.
The adenovirus vector vaccine is safe because the adenovirus cannot replicate or cause disease in human cells, and the SARS-CoV-2 spike protein cannot cause COVID-19 without the rest of the coronavirus.
This approach is not new. Johnson & Johnson used a similar method to make their Ebola vaccine, and the AstraZeneca-Oxford COVID-19 vaccine is also an adenovirus vector viral vaccine.
2. How effective is it?
Analysis by the FDA found that Johnson & Johnson’s COVID-19 vaccine was 72% effective in preventing all COVID-19 and 86% effective in preventing severe cases of the disease in the United States. While there is still a chance that a vaccinated person could get sick, this suggests that they will have to go to hospital or die of COVID-19 much less often.
A similar experiment in South Africa, where a new, more contagious variant dominates, produced similar results. The researchers found that the Johnson & Johnson vaccine was slightly less effective at preventing all diseases – 64% overall – but still 82% at preventing major diseases. The FDA report also shows that the vaccine also protects against other variants from the UK and Brazil.
3. How is it different from other vaccines?
The most fundamental difference is that the Johnson & Johnson vaccine is an adenovirus vector vaccine while the Moderna and Pfizer vaccines are both mRNA vaccines. Messenger RNA vaccines use genetic instructions from the coronavirus to tell a person’s cells to make the spike protein, but these don’t use any virus other than a vector. There are also many practical differences.
Both mRNA-based vaccines require two shots. The Johnson & Johnson vaccine only requires a single dose. This is important when vaccines are scarce.
The Johnson & Johnson vaccine can also be stored at much warmer temperatures than the mRNA vaccines. The mRNA vaccines must be shipped and stored at sub-zero or freezing temperatures and require an intricate cold chain to safely distribute them. The Johnson & Johnson vaccine can be stored in a regular refrigerator for at least three months, which makes it much easier to use and distribute.
In terms of effectiveness, it is difficult to directly compare the Johnson & Johnson vaccine with the mRNA vaccines because clinical trials differ. While Moderna and Pfizer vaccines are about 95% effective in preventing COVID-19 disease, the studies were conducted in the summer and fall of 2020 before newer, more contagious variants became widespread. Moderna and Pfizer vaccines may not be as effective against the new variants, and Johnson & Johnson studies have recently been conducted taking into account the effectiveness of the vaccine against these new variants.
4. Should I choose one vaccine over another?
While the overall effectiveness of Moderna and Pfizer vaccines is higher than that of Johnson & Johnson’s vaccine, don’t wait to have your vaccine choice – which is probably still a long way off anyway. The Johnson & Johnson vaccine is almost as good as the mRNA-based vaccines at preventing serious diseases, and that’s what really matters.
The Johnson & Johnson vaccine and other viral vector vaccines such as AstraZeneca’s are particularly important to the global vaccination effort. From a public health perspective, having multiple COVID-19 vaccines is important, and the Johnson & Johnson vaccine is a very welcome addition to the vaccine arsenal. No freezer is required, which makes shipping and storage a lot easier. It is a one-shot vaccine that makes logistics a lot easier compared to organizing two doses per person.
As many people as possible need to be vaccinated as soon as possible to limit the development of new coronavirus variants. Johnson & Johnson is expected to ship nearly four million doses once the FDA grants approval for the emergency. A third approved vaccine in the US will be a huge step towards meeting vaccination needs and stopping this pandemic.
Maureen Ferran, Associate Professor of Biology, Rochester Institute of Technology
This article is republished by The Conversation under a Creative Commons license. Read the original article.
And the award for the best scene dealer goes to …Kelleth Cuthbert.
Don’t you know that name How about “”Fiji Water Girl, “Do you remember her? It’s been two years since Fiji Water Girl became the unexpected breakout star of the 2019 Golden Globes, thanks to her strategic placement behind some of the biggest names on the red carpet in seemingly every photo, that they did.
Amy Adams? Check. Richard Madden? Yes. Nicole Kidman? You bet. It’s good that Kelleth, a Canadian actress and model, carried a tray with a water bottle all night considering how thirsty she must have been, right?
But the hustle and bustle was so impressive that E! News actually helped with hydration and gave Kelleth, 33, her own honorary award after taking the internet by storm for “Best Supporting Actress on a Red Carpet”.
“I want to thank water. If these celebrities weren’t so thirsty, I wouldn’t have been able to serve the way I did,” she said in her acceptance speech. “My performance would really not have been possible without you.”
The Food and Drug Administration has approved Johnson & Johnson’s Covid-19 vaccine for emergency use. This gives the US a third tool to fight the pandemic as highly contagious variants are gaining a foothold across the country.
With the FDA’s approval for the emergency on Saturday, the federal government’s plan begins to distribute nearly 4 million doses of J & J’s vaccine to states, pharmacies and community health centers across the country next week. Unlike Pfizer and Moderna vaccines, patients with the single dose of J&J do not need to take a second dose and can be stored at refrigerator temperature for months.
J & J’s vaccine “makes it easier to use in many contexts,” said Dr. Nancy Messonnier, director of the National Center for Immunization and Respiratory Diseases of the CDC, told the Journal of the American Medical Association during a question and answer session Friday. “I suspect that much of the national health consideration given to these vaccines is more about the ease of use of the J&J vaccine and how it might be better suited to some populations.”
Initially, doses would be limited, J&J said. The company expects to drop 20 million doses by the end of March, said Dr. Richard Nettles, vice president of medical affairs in the US, told the House legislature on Tuesday. J&J has signed a contract with the US government to supply 100 million doses of its vaccine by the end of June. US officials say they are working with the company to increase supply as soon as possible.
In the past few weeks, US health officials have urged Americans to get vaccinated as soon as possible. Officials are increasingly concerned about new, emerging variants of the virus, particularly strain B.1.351, which has been shown to decrease the effectiveness of vaccines both in market and in development. On Friday, the head of the Centers for Disease Control and Prevention, Dr. Rochelle Walensky, the declines in Covid-19 cases reported in the US since early January could flatten as the variants spread.
J&J submitted its Covid vaccine data to the FDA on February 4th. The vaccine’s level of protection varies from region to region, J&J said, with the shot showing an effectiveness of 66% overall, 72% in the US, 66% in Latin America and 57% in South Africa, where variant B.1.351 is spreading rapidly. However, FDA documents show that the vaccine was 64% effective in South Africa after about a month. The company said the vaccine prevented 100% of hospital stays and deaths.
The Pfizer vaccine was found to be 95% effective against Covid-19, while the Moderna vaccine was around 94% effective. Infectious disease experts pointed out that J & J’s numbers cannot be used as a head-to-head comparison with the other two vaccines because it is a single dose and the company’s study was conducted when more infections, as well as new, more contagious variants occurred.
The FDA has announced that it will approve a Covid-19 vaccine that is safe and at least 50% effective. In comparison, the flu vaccine generally reduces the risk of developing influenza by 40% to 60% compared to people who were not vaccinated, according to the CDC.
The FDA has approved J & J’s vaccine for people 18 years of age and older. This is not the same as a full approval which requires more data and which can typically take several months longer. J&J, like Pfizer and Moderna, has only submitted safety data for two months, but the agency typically takes six months for full approval. The FDA approved the emergency use of hydroxychloroquine to treat Covid-19 in March but revoked it in June after additional data showed it provided “no indication of benefit” in coronavirus patients.
The FDA was expected to approve J & J’s emergency vaccine.
The agency’s announcement comes after a key panel unanimously endorsed the emergency vaccine on Friday. The FDA’s Advisory Panel on Vaccines and Related Biological Products plays a key role in approving influenza and other vaccines in the United States and verifying that the vaccines are safe for public use. While the FDA does not have to follow the advisory board’s recommendation, it often does.
After the vote, Dr. Archana Chatterjee, an infectious disease expert at Chicago Medical School and voting committee member, said J & J’s vaccine will help “meet the needs of the moment” as states complain that there is insufficient supply Pfizer and Moderna gives vaccinations.
“We have to get this vaccine out now,” said Dr. Jay Portnoy, professor at UMKC School of Medicine and voting committee member, after the vote. He added, “We are in a hurry” as the variants pose a threat to the nation’s progress on the pandemic.
No specific safety concerns were identified with J & J’s vaccine. Headache, fatigue, and muscle aches were some of the most common side effects among people who received the vaccination, according to an FDA report released Wednesday. There have also been reports of nausea, fever and injection site pain, the report said.
Macaya Douoguih, director of clinical development and medical affairs for the vaccines division at J & J, Janssen, told the FDA panel on Friday that two people had severe allergic reactions shortly after receiving the vaccine. One of the people participated in an ongoing study in South Africa and developed anaphylaxis, a severe and life-threatening allergic reaction.
The company has announced that it will ship the vaccine, which contains five doses per vial, at 36 to 46 degrees Fahrenheit. In comparison, Pfizer’s vaccine must be stored in ultra-cold freezers that are between minus 112 and minus 76 degrees Fahrenheit. However, the FDA recently allowed the company to store its vaccine for two weeks at temperatures commonly found in pharmaceutical freezers. Moderna vaccine must be shipped at 13 to 5 degrees above zero Fahrenheit.
As expected, this was an easy job for Saul “Canelo” Alvarez.
The WBA (Super), WBC and The Ring super middleweight champion successfully defended his title by slapping Avni Yildirim and forcing his opponent to sit in the chair after three rounds at Hard Rock Stadium in Miami Gardens, Florida on Saturday night stand.
Now, on May 8th, there will be an agreement battle against WBO champion Billy Joe Saunders.
This marked a 70-day turnaround for Canelo after his strike against Callum Smith in December when he won the super middleweight title. To hold on to his WBC title, he had to face number 1 in Yildirim. With the dream of being the undisputed champion, he violently fulfilled his obligation.
“I needed the knockout and that’s exactly what I did,” Canelo said.
Saying it was an easy night for the 30-year-old might sell her briefly. Canelo came out firing and Yildirim could do nothing but eat leather when he felt the wrath of the Mexican.
When Canelo realized that Yildirim had no answers, he went to work and had a goal to begin the second round. Canelo dug bullets into the body, landing overcuts, and wrapping hooks around gloves. In the third round, Canelo scored his first knockdown with his right hand in the middle. It was clear that Yildirim had no chance when Canelo beat his opponent. Coach Joel Diaz didn’t like what he saw of his fighter and decided to leave Yildirim on the stool for the fourth round.
The expected easy win paves the way for Canelo to further unify the division.
“I will fight everyone,” he said. “I always fight the best. It doesn’t matter. Here I am making history. I had to fight Yildirim to keep my championship.”
And now he has to face the unbeaten Saunders on the weekend of Cinco De Mayo.
Here’s how it all went. (All times east.)
MORE: Join DAZN to watch Canelo and other fighters
Canelo Alvarez is eliminated from Anvi Yildirim after three rounds
Round 3 (10:54 p.m.): The third round starts where the second left off, as Canelo repeatedly lands on the body and drops Yildirim with a straight right hand. Yildirim is up but getting pulverized. Canelo is looking for the perfect shot to end this. Yildirim manages to survive, but it is obvious that this will soon be over. 10-8, Canelo (30-26, Canelo)
Round 2 (10:50 p.m.): Canelo rocks Yildirim with an uppercut and lands a hook. Canelo only shoots and lands what he wants. This is target practice. Canelo with liver shot, uppercut and hook. It is abusive. Yildirim is nothing more than a heavy bag with legs. 10-9, Canelo (20-18, Canelo)
Round 1 (10.45 p.m.): Canelo opens with a left hook that moves Yildirim. He wastes little time on the offensive. Canelo digs for the body. Yildirim has no replies yet. A fighter known to be aggressive, Canelo tamed the Turkish warrior. 10-9, Canelo
10:34 pm: Canelo goes to the ring with an appearance by pop star J Balvin. Dancers and pyro set the stage for the pound-for-pound king of boxing.
10:30 p.m .: Avni Yildirim made his way to the ring. He says Canelo has never fought a Turkish warrior before. I’m not sure if this is important, but it sounds good.
10:24 p.m .: We got used to waiting a long time when Canelo is fighting. After more than 30 minutes we are finally at the national anthems. The main event is (finally) just around the corner!
9:50 pm: It’s time for the main event! Canelo Alvarez will defend his WBC, WBA (Super) and The Ring super middleweight titles against WBC No. 1 contender Avni Yildirim. Few expect Yildirim to be a major threat, but anything can happen. Right?
9:43 pm: McWilliams Arroyo has won the provisional WBC title with a break in the fifth round. Rodriguez just couldn’t take the pressure and was pounded from column to column. With no conceivable way to win, Rodriguez’s corner stopped the fight to save their fighter from further harm. We will get the fight between Arroyo and Julio Cesar Martinez as soon as Martinez is healed.
9.40 p.m.: As expected, this fight was one-way traffic. It took Arroyo Rodriguez a minute to find out, but by the fourth round he increased the pressure to get his first knockdown. Rodriguez has to do something special not to get stopped in the fifth.
9:16 pm: The co-main event is next as McWilliams Arroyo will battle late successor Abraham Rodriguez for the WBC provisional flyweight title. Julio Cesar Martinez broke his hand earlier this week and Rodriguez flew to Miami on Friday to take his place. Arroyo is expected to win but Rodriguez should be commended for stepping up at the last minute.
9:10 pm: The hype train for Zhang Zhilei was derailed when, despite losing the first three rounds, he drew a majority against Jerry Forrest. But the big man was exhausted and allowed Forrest to take over the second half of the fight. A docked point in the 9th round was the differentiator, with one judge seeing it for Forrest 95-93 and the other two judges even having it at 93-93. Zhang will surely have to go back to the drawing board and find out what went wrong.
9:07 pm: The fight has certainly turned as Zhang did next to nothing in the second half of the fight and lost a point in round 9 while Forrest continued to rework it. Forrest hummed Zhang with a combination late on the 10th and injured the tall man. Zhang trips over the ring while Forrest chases after him. Zhang manages to survive, but could we have a surprise on our hands?
8:51 pm: Zhang dropped Forrest once in the first three rounds, but Forrest refuses to walk away. He is consistently overwhelmed and continues to push forward. By the time we finish the sixth lap, Zhang appears to be completely gassed. Maybe Forrest can make a comeback?
8:22 pm: The heavyweights are about to throw the gigantic 6-6 Chinese monster Zhang Zhilei against Jerry Forrest next. Can Zhilei claim his 23rd victory?
8:09 pm: Well, he didn’t make the last 16 but Diego Pacheco improved to 11-0 and went eight rounds with a unanimous decision win for the first time in his career. Pacheco controlled much of the action and seemed to be learning a lot as he began his ascent to the title shot by facing an opponent who had never been stopped before. It wasn’t easy, but definitely for Pacheco.
7:51 pm: We’re in the middle of a fight and both of them are still upright. Pacheco is ahead by a nose, but Gomez Jr. has absolutely come to fight. It is Pacheco’s activity behind the push that has got the job done so far. Can Gomez find a way to turn this fight around?
19:30 o’clock: Next up is another young talent as Diego Pacheco appears to go undefeated against Rodolfo Gomez Jr. Pacheco’s height advantage is nullified here, as they both soar at 6’4 “and share a similar range. Both have promised short nights. But who will be on screen?
7:24 pm: We’re alive and it wasn’t long before the hot prospect Marc Castro made his presence felt. Castro faced former UFC flyweight title challenger John Moraga and made sure there would be no promotion of Clay Collard by the former MMA fighter as he dropped his opponent three times in two rounds to get the hiatus to reach. Castro dropped Moraga with the first push he threw, and from there it went downhill. A combination dropped Moraga again in the second round and finished him off with a short uppercut. Castro improves to 2-0 and it is obvious that he will fight for a world title in the next 24 months.
How to see Canelo versus Yildirim
Live broadcast: DAZN
PPV price: $ 19.99 / month or $ 99.99 / year
The fight between Canelo and Yildirim will be broadcast live on DAZN in more than 200 countries and territories worldwide, including the US and Canada.
Those looking to watch the battle can find DAZN on a number of different systems including, but not limited to, Amazon Fire TV / Stick, Android, Apple TV, Google Chromecast, iPhone and iPad, Playstation 4, Playstation 5, Xbox One, Xbox Series X / S and Roku. The DAZN app is also available for smart TVs from LG, Samsung and Vizio, Xfinity X1 and Flex.
Viewers can also find it on DAZN.com using browsers such as Chrome, Firefox, Internet Explorer, and Safari.
Click here to learn more about DAZN.
Canelo vs Yildirim battle card
Canelo Alvarez def. Avni Yildirim on TKO in the 3rd round (2:59).
McWilliams Arroyo def. Abraham Rodriguez on the 5th round TKO (1:41).
Zhang Zhilei and Jerry Forrest are fighting for the majority (93-93, 93-93. 95-93).
Diego Pacheco def. Rodolfo Gomez Jr. by unanimous decision (79-73, 79-73, 79-73).
Marc Castro def. John Moraga on the 2nd round TKO (2:29).
Lightning is one of the most powerful forces in nature. Up to 1 billion volts of electricity can flow into a strike in less than a second. Such a large build-up of energy can even be produced by a relatively simple cause – two particles rubbing against each other. A team at the University of Oregon has now investigated whether these simple interactions can cause lightning in a place they haven’t seen before – Mars.
The simple answer to this question is: yes, during dust storms or other events that involve a lot of dust flying around, there will be a “lightning bolt” on Mars, but not nearly as large as the storms observed on Earth. The Martian atmosphere is too thin to hold the voltages required to produce the dramatic lightning strikes common on Earth.
UT video about the lack of atmosphere on Mars.
However, there will still be much smaller electrical discharge events. They can even be visible at close range at certain wavelengths, as dust storms can give off a faint glow if they are not exposed to direct sunlight. This glow will mainly come in the form of radio waves that are invisible to the human eye.
Many researchers have previously tried to model the electrical activity of the Martian atmosphere. The UO team took a different route, taking into account many variables that confused previous efforts. They used a simple glass cylinder with dust particles in it. However, they made it their goal to take into account two different considerations that other experiments failed to take into account.
The yellow and white cloud in the lower center of this image is a Martian “dust tower” – a concentrated cloud of dust that can be thrown dozens of miles above the surface. The blue and white feathers are clouds of water vapor. This image was captured by NASA’s Mars Reconnaissance Orbiter on November 30, 2010. Photo credit: NASA / JPL-Caltech / MSSS
First, they charged the cylinder itself electrically so that it repels the dust used in the experiment. The cylinder itself was relatively small – four inches in diameter and eight inches in length. In the past, researchers had allowed dust to come into contact with the glass cylinder, which was unlike any material on Mars itself. There were concerns that the ability to contact non-Martian materials would affect the study’s results.
Another challenge to previous experiments was using rocks similar enough to what was found on Mars. Joshua Méndez Harper, a research engineer and author of the paper, had relatively easy access to the type of volcanic rock, similar to that found on Mars, when he worked in the UO’s volcanology department.
Graphic of the test setup for the isolation of the Martian material. Photo credit: Méndez Harper et al.
The combination of only Martian analog material in the cylinder as well as the isolation of adjacent non-Martian material means that this is the closest possible way to truly model the environment on Mars electrically.
The core of why the Martian atmosphere would not support the great lightning strikes on Earth is the lack of atmosphere. The electric fields that the sparse Martian atmosphere can withstand are around twenty thousand volts per meter, compared to three million volts per meter in the much denser Earth’s atmosphere.
In this image of the Earth from the International Space Station, air glow (along with a lightning sprite) is visible. Photo credit: NASA
Since lightning is a disturbance of the atmosphere itself, the higher the electric field to which it is exposed, the more spectacular the lightning is. At the levels the Martian atmosphere is exposed to, only small electrostatic discharges are likely to be supported, similar to those you would experience if you rub your socks on a carpet and touch a metal doorknob in winter.
This is actually good news for the current residents of Mars – rovers like perseverance and curiosity can withstand the small electrical discharges that the Martian atmosphere allows. For larger discharges, the guiding frame of the rovers could act like a lightning rod, with less than ideal consequences for the rovers themselves.
UT video about Martian dust storms.
The lack of a lightning bolt could also affect longer-term settlement, although the possible effects are still unclear. In addition, lightning plays a role in the formation of organic compounds. It is not yet clear whether the denser Martian atmosphere of the past was able to support the high-energy bolts required to produce these organic compounds.
For now, we can say that Endurance and the other rovers on the surface will most likely not be the focus of a visible thunderstorm. But look carefully with the right gear and you may be able to see a faint glow surrounding them.
Learn more: UO – Mars rover safe from lightning strikes, new UO research results NSF – Mars rover safe from lightning strikes, research results UT – lightning detected on Mars Icarus – Detection of spark discharges in a moving Martian dust simulant isolated from foreign surfaces
The multi-armed bandit must find ways to discover one of several solutions through trial and error
Every reinforcement learning algorithm must find the right balance between exploiting optimal solutions and exploring new options
Contextual bandits use function approximation to factor in the individual characteristics of ad viewers
