Stephen Sekula steve@hub.polari.us

Dallas, TX, USA

Husband; Professor of Physics; I teach at SMU in Dallas, TX; I study the Higgs Particle with the ATLAS Experiment at the Large Hadron Collider at CERN; writer and blogger; drummer; programmer; teacher; scientist; traveler; runner; gardener; open-source aficionado.

  • 639: Colliding Particles to Comprehend the Components of Matter - Dr. Jon Butterworth

    PumpCast at 2022-01-17T08:14:15Z

    "639: Colliding Particles to Comprehend the Components of Matter - Dr. Jon Butterworth" Dr. Jon Butterworth is a Professor of Physics at University College London. He works on the Large Hadron Collider at CERN in Geneva. They are smashing particles together at extremely high energies and measuring what happens. Collecting data on these particle collisions provides information about the smallest and most basic components of our universe. Outside of science, Jon has two kids, and he spends most of his leisure time hanging out with them. He is also an avid writer and finds that writing is a good way to relax. At the same time, Jon enjoys activities like skiing and giving guitar performances. He received his B.A. in Physics and his Ph.D. in Particle Physics from the University of Oxford. Afterwards, Jon was hired by Pennsylvania State University to conduct postdoctoral research at the Deutsches Elektronen-Synchrotron (DESY) in Hamburg, Germany before joining the faculty at UCL where he is today. John is a Fellow of the Institute of Physics and recipient of their Chadwick Prize. He has also been awarded a Wolfson Research Merit Award from the Royal Society, an Alexander von Humboldt Fellowship, and a Particle Physics and Astronomy Research Council Senior Research Fellowship. In addition, Jon is the author of the book Most Wanted Particle and author of a blog for The Guardian called Life and Physics. In this interview, Jon shares more about his journey through life and science. https://peoplebehindthescience.libsyn.com/639-colliding-particles-to-comprehend-the-components-of-matter-dr-jon-butterworth ( Feed URL: http://peoplebehindthescience.libsyn.com/rss )

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  • Astronomy Picture of the Day for 2022-01-15 12:30:03.008450

    Astronomy Picture of the Day (Unofficial) at 2022-01-15T18:30:03Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2022 January 15
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    Galileo's Europa
    Image Credit: NASA, JPL-Caltech, SETI Institute, Cynthia Phillips, Marty Valenti

    Explanation: Looping through the Jovian system in the late 1990s, the Galileo spacecraft recorded stunning views of Europa and uncovered evidence that the moon's icy surface likely hides a deep, global ocean. Galileo's Europa image data has been remastered here, with improved calibrations to produce a color image approximating what the human eye might see. Europa's long curving fractures hint at the subsurface liquid water. The tidal flexing the large moon experiences in its elliptical orbit around Jupiter supplies the energy to keep the ocean liquid. But more tantalizing is the possibility that even in the absence of sunlight that process could also supply the energy to support life, making Europa one of the best places to look for life beyond Earth. What kind of life could thrive in a deep, dark, subsurface ocean? Consider planet Earth's own extreme shrimp.

    Tomorrow's picture: a very cloudy day


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  • ATLAS gives new insight into the internal structure of the proton

    ParticleNews at 2022-01-13T08:27:46Z

    "ATLAS gives new insight into the internal structure of the proton" ATLAS gives new insight into the internal structure of the proton While the Large Hadron Collider (LHC) is well known for smashing protons together, it is actually the quarks and gluons inside the protons – collectively known as partons – that are really interacting. Thus, in order to predict the rate of a process occurring in the LHC – such as the production of a Higgs boson or a yet-unknown particle – physicists have to understand how partons behave within the proton. This behaviour is described in Parton Distribution Functions (PDFs), which describe what fraction of a proton’s momentum is taken by its constituent quarks and gluons. Knowledge of PDFs has traditionally come from lepton–proton colliders, such as HERA at DESY. These machines use point-like particles, such as electrons, to directly probe the partons within the proton. Their research revealed that, in addition to the well-known up and down quarks that are inside a proton, there is also a sea of other quark–antiquark pairs in the proton. This sea is theoretically made of all types of quarks, bound together by gluons. Now, studies of the LHC’s proton–proton collisions are providing a detailed look into PDFs, in particular the proton’s gluon and quark-type composition. The ATLAS Collaboration has just released a new paper combining LHC and HERA data to determine PDFs. The result uses ATLAS data from several different Standard Model processes, including the production of W and Z bosons, pairs of top quarks and hadronic jets (collimated sprays of particles). The strange quark’s contribution to PDFs was expected to be lower than that of lighter quarks. The new paper confirms a previous ATLAS result, which found that the strange quark is not substantially suppressed at small proton momentum fractions and extends this result to show how suppression kicks in at higher momentum fractions. Several experiments and theoretical groups around the world are working to understand PDFs, as variance in these results could impact high-energy searches for physics beyond the Standard Model. Achieving high-accuracy PDFs is needed if physicists are to find evidence for new-physics processes – which is where the ATLAS analysis contributes most powerfully.  The ATLAS Collaboration is able to assess the correlations of the systematic uncertainties between their datasets and account for them – an ability put to great effect in their new PDF result. Such knowledge was not previously available outside ATLAS, making this result a new “vademecum” for global PDF groups. Read the full article on the ATLAS website. Additional links CERN Preprint: CERN-EP-2021-239 arXiv: 2112.11266 Figures: https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2020-32 Lepton photon talk: https://indico.cern.ch/event/949705/contributions/4556026/  cagrigor Wed, 01/12/2022 - 17:17 Byline ATLAS collaboration Publication Date Wed, 01/12/2022 - 17:10 http://home.web.cern.ch/news/news/physics/atlas-gives-new-insight-internal-structure-proton ( Feed URL: http://home.web.cern.ch/about/updates/feed )

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  • Astronomy Picture of the Day for 2022-01-12 12:30:02.584313

    Astronomy Picture of the Day (Unofficial) at 2022-01-12T18:30:03Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2022 January 12
    The featured image shows Comet Leonard as it appeared
just before sunset on 2022 January 2 from Siding Spring, Australia. 
The comet shows a bright green coma and a long and detailed ion tail.
Please see the explanation for more detailed information.

    Comet Leonard Closeup from Australia
    Image Credit & Copyright: Blake Estes (itelescope.net)

    Explanation: What does Comet Leonard look like up close? Although we can't go there, imaging the comet's coma and inner tails through a small telescope gives us a good idea. As the name implies, the ion tail is made of ionized gas -- gas energized by ultraviolet light from the Sun and pushed outward by the solar wind. The solar wind is quite structured and sculpted by the Sun's complex and ever changing magnetic field. The effect of the variable solar wind combined with different gas jets venting from the comet's nucleus accounts for the tail's complex structure. Following the wind, structure in Comet Leonard's tail can be seen to move outward from the Sun even alter its wavy appearance over time. The blue color of the ion tail is dominated by recombining carbon monoxide molecules, while the green color of the coma surrounding the head of the comet is created mostly by a slight amount of recombining diatomic carbon molecules. Diatomic carbon is destroyed by sunlight in about 50 hours -- which is why its green glow does not make it far into the ion tail. The featured image was taken on January 2 from Siding Spring Observatory in Australia. Comet Leonard, presently best viewed from Earth's Southern Hemisphere, has rounded the Sun and is now headed out of the Solar System.

    Tomorrow's picture: open space


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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  • Jason Self at 2022-01-06T14:12:43Z

    Colin's ultrasound is today.

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  • JanKusanagi @identi.ca at 2021-12-21T16:09:11Z

    You're THE KING!! 👑

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  • Jason Self at 2021-12-26T18:42:19Z

    It's snowing in Seattle. Nova (the cat) has been going around to all of the windows, looking and watching. She's about 1.5 years old and probably didn't see any in Hawaii. It's probably her first snow. I go outside to get some snow on a plate and bring it in for her to investigate further. She sniffs it, eats some, pokes at it with her paw, bats some around, and generally seems to have a good time with it. #snowcat

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  • Astronomy Picture of the Day for 2021-12-23 12:30:01.479506

    Astronomy Picture of the Day (Unofficial) at 2021-12-23T18:30:02Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2021 December 23
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    Three Planets and a Comet
    Image Credit & Copyright: Tunc Tezel (TWAN)

    Explanation: Are you still looking for that perfect holiday gift for an astronomer? If your night sky is dark and horizon clear enough, the Solar System may have done your shopping for you. Send them outside after sunset to see three planets and a comet. In this snapshot of the December solstice evening sky from the village of Kirazli, Turkey the brightest celestial beacon is Venus, close to the southwestern horizon at the right. Look left and up to find Saturn shining between clouds. Follow that line farther left and up to bright Jupiter, the Solar System's ruling gas giant. This year's surprise visitor to the inner Solar System, Comet Leonard (C/2021 A1), is near the horizon too. The comet is fainter but forms a nearly equilateral triangle with planets Venus and Saturn in this view. After a dramatic brightening in recent days the comet is just visible to the unaided eye, though a nice pair of binoculars is always a good idea.

    Notable Submissions to APOD: Planetary Alignment: 2021 December
    Tomorrow's picture: pixels in space


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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    Piękne intermedialna.pl

    Tupulpo at 2021-12-23T22:10:07Z

  • JanKusanagi @identi.ca at 2021-12-25T21:56:22Z

    Now to hold our breath for ~1 month 😂

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  • JanKusanagi at 2021-08-11T01:09:01Z

    YEEEEEEEEEHAAAWWWW!!

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  • JanKusanagi at 2021-08-09T22:52:57Z

    🤘😎🤘 !!

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  • JanKusanagi at 2021-08-09T23:54:29Z

    Go judge!!! 🙌

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  • JanKusanagi at 2021-05-29T23:07:44Z

    When life gives Dr. Sekula lemons... 😎

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    @jankusanagi@datamost.com The wisdom of Cave Johnson: https://youtu.be/ELkgiJD9KuM

    Stephen Sekula at 2021-05-31T00:08:53Z

  • JanKusanagi at 2021-05-05T23:23:10Z

    They know mobile OSes suck, so they needed to continue the trend 😎

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  • at 2021-04-02T01:58:54Z

    Bus Ride Buddy 公車旅伴

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  • Astronomy Picture of the Day for 2021-03-31 12:30:01.412753

    Astronomy Picture of the Day (Unofficial) at 2021-03-31T17:30:02Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2021 March 31
    Polarization of light emitted from the near the black hole M87 is pictured. See Explanation.

    M87's Central Black Hole in Polarized Light
    Image Credit: Event Horizon Telescope Collaboration; Text: Jayanne English (U. Manitoba)

    Explanation: To play on Carl Sagan’s famous words "If you wish to make black hole jets, you must first create magnetic fields." The featured image represents the detected intrinsic spin direction (polarization) of radio waves. The polarizationi is produced by the powerful magnetic field surrounding the supermassive black hole at the center of elliptical galaxy M87. The radio waves were detected by the Event Horizon Telescope (EHT), which combines data from radio telescopes distributed worldwide. The polarization structure, mapped using computer generated flow lines, is overlaid on EHT’s famous black hole image, first published in 2019. The full 3-D magnetic field is complex. Preliminary analyses indicate that parts of the field circle around the black hole along with the accreting matter, as expected. However, another component seemingly veers vertically away from the black hole. This component could explain how matter resists falling in and is instead launched into M87’s jet.

    Tomorrow's picture: cleaning mars


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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  • Astronomy Picture of the Day for 2021-03-21 12:30:01.987368

    Astronomy Picture of the Day (Unofficial) at 2021-03-21T17:30:02Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2021 March 21
    The ancient Antikythera mechanism is shown, the oldest known orrery. See Explanation.

    The Antikythera Mechanism
    Image Credit & License: Marsyas, Wikipedia

    Explanation: No one knew that 2,000 years ago, the technology existed to build such a device. The Antikythera mechanism, pictured, is now widely regarded as the first computer. Found at the bottom of the sea aboard a decaying Greek ship, its complexity prompted decades of study, and even today some of its functions likely remain unknown. X-ray images of the device, however, have confirmed that a main function of its numerous clock-like wheels and gears is to create a portable, hand-cranked, Earth-centered, orrery of the sky, predicting future star and planet locations as well as lunar and solar eclipses. The corroded core of the Antikythera mechanism's largest gear is featured, spanning about 13 centimeters, while the entire mechanism was 33 centimeters high, making it similar in size to a large book. Recently, modern computer modeling of missing components is allowing for the creation of a more complete replica of this surprising ancient machine.

    Tomorrow's picture: surround orion


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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  • Astronomy Picture of the Day for 2021-03-08 12:30:02.356952

    Astronomy Picture of the Day (Unofficial) at 2021-03-08T18:30:03Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2021 March 8
    See Explanation.
Moving the cursor over the image will bring up an annotated version.
Clicking on the picture will download
the highest resolution version available.

    Three Tails of Comet NEOWISE
    Image Credit & Copyright: Nicolas Lefaudeux

    Explanation: What created the unusual red tail in Comet NEOWISE? Sodium. A spectacular sight back in the summer of 2020, Comet NEOWISE, at times, displayed something more than just a surprisingly striated white dust tail and a pleasingly patchy blue ion tail. Some color sensitive images showed an unusual red tail, and analysis showed much of this third tail's color was emitted by sodium. Gas rich in sodium atoms might have been liberated from Comet NEOWISE's warming nucleus in early July by bright sunlight, electrically charged by ultraviolet sunlight, and then pushed out by the solar wind. The featured image was captured in mid-July from Brittany, France and shows the real colors. Sodium comet tails have been seen before but are rare -- this one disappeared by late July. Comet C/2020 F3 (NEOWISE) has since faded, lost all of its bright tails, and now approaches the orbit of Jupiter as it heads back to the outer Solar System, to return only in about 7,000 years.

    Astrophysicists: Browse 2,400+ codes in the Astrophysics Source Code Library
    Tomorrow's picture: mars 360


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  • Searching for Higgs boson twins

    ParticleNews at 2021-02-25T16:27:38Z

    "Searching for Higgs boson twins"

    Higgs-boson pairs could help scientists understand the stability of our universe. The trick is finding them.

    Particle collision visualization

    In 2012, scientists on the CMS and ATLAS experiments at CERN’s Large Hadron Collider discovered the Higgs boson. Now, they’re looking for two Higgs bosons born from a single collision.

    “The Higgs self-coupling has implications in understanding the origin and ultimate fate of the universe,” says Nan Lu, a postdoc at the California Institute of Technology supported by the US Department of Energy’s Office of Science. “This process is a lighthouse that guides the future of particle physics.”

    Higgs bosons are the physical manifestations of the Higgs field, an invisible medium that is woven into the fabric of spacetime.

    “Elementary particles obtain their masses through interaction with this Higgs field,” Lu says. “Without the Higgs field, all elementary particles would be massless and traveling at the speed of light. The universe would not look the same as it does today.”

    The LHC can generate Higgs bosons by colliding protons and transmitting the stored energy into the Higgs field—much like a pebble striking the surface of a river and transferring its kinetic energy into a ripple. This process happens at a rate of about one in a billion collisions.

    On even rarer occasions, this energy transfer can generate not one but two Higgs bosons at the same time. These Higgs boson twins could help scientists characterize a largely unmeasured facet of the Higgs mechanism: the shape of the Higgs potential.

    The boson, the field and the Higgs potential

    The Brout-Englert-Higgs mechanism—to use its full name—consists of three interlinking facets: the Higgs boson, the Higgs field and the Higgs potential.

    “You can think about it like a river,” says Irene Dutta, a graduate student at Caltech. “The Higgs boson is a ripple, the Higgs field is the water, and the Higgs potential is the shape of the riverbed.”

    The Higgs boson—the ripple—gives scientists a glimpse of the otherwise invisible Higgs field—the water. But underneath it all is the Higgs potential—the riverbed, or a mathematical function that determines the different possible energy states of the Higgs field.

    “A river might seem calm and flat,” Dutta says, “but there could be a waterfall that leads to much lower ground that we cannot see from where we are.”

    If the potential dropped and the Higgs field spontaneously fell into a lower energy state, the universe as we know it would evaporate.

    “The current calculations indicate that we could be living in a false vacuum,” says Thong Nguyen, a graduate student at Caltech. “This means that at any moment, the Higgs field could tunnel through the potential barrier to a true negative-energy vacuum, creating an expanding singularity bubble that eventually swallows up the entire universe.”

    (The universe has yet to disappear in its 14 billion years, at least, and physicists do not anticipate that it will happen anytime soon.)

    The origin of matter

    According to Nguyen, the Higgs field has already fallen from a high energy state into a lower one once before.

    “Right after the Big Bang, when the universe was a hot and dense soup, the Higgs field was perfectly symmetrical and did not interact with other particles,” Nguyen says. “But as the universe cooled, the Higgs field underwent a phase transition. Symmetry broke, and then particles were able to interact with the Higgs field to acquire mass.”

    This first transition could be the missing link in one of the biggest mysteries in physics: the dominance of matter over its equal-and-opposite counterpart, antimatter.

    “Right after the Big Bang, we should have had equal amounts of matter and antimatter,” Lu says. “Today, there is a large amount of matter and almost no antimatter.”

    The evolution of the Higgs field during the primordial universe could be responsible for this imbalance.

    “If it’s a smooth transition, as our models predict, then the entire Higgs field would have cooled homogeneously, like water slowly freezing into ice,” Nguyen says. “But if it’s an abrupt transition, then bubbles could have formed and eventually expanded to fill the entire universe.”

    These bubbles in the Higgs field could have serendipitously sheltered the small excess of matter that eventually formed everything.

    Higgs self-coupling

    The Higgs potential regulates the behavior of Higgs bosons, including their interactions with one another. If scientists can find and study Higgs-boson pairs, then they can work backwards and indirectly probe the Higgs potential’s shape.

    “First we need to measure the rate of Higgs-boson pair production,” Lu says. “Then we want to measure the properties of these two Higgs bosons.”

    The scarcity of this process makes it a classic needle-in-a-haystack problem.

    “During Run II [which ended in December 2018], the LHC would have generated about 7.5 million Higgs bosons,” Dutta says. “But it would have only produced about 4500 Higgs-boson pairs.”

    Higgs bosons are notoriously difficult to separate from look-alike subatomic processes. Even for a very clean signature—a Higgs boson decaying into two photons—there are 10 identical background events for every real Higgs boson.

    “We’re completely swamped by the background,” Dutta says. “The di-Higgs production process is not an easy observation to make and our best chance of seeing it is with the High-Luminosity LHC upgrade,” now in full progress. 

    Once this upgrade is completed later this decade, future runs will increase the total number of potential collisions scientists have to study by at least a factor of 10.

    The overall US contributions to the LHC experimental research program and HL-LHC upgrade are funded by the US Department of Energy and the National Science Foundation. With the HL-LHC only a few years away, scientists are already honing their analysis methods.

    They have begun to apply machine-learning techniques inspired by natural language processing. Nguyen is developing and training machine-learning algorithms to recognize the subtle differences between Higgs boson signatures and look-alike background processes (much like a natural-language-processing algorithm separates similar sounding words like “close” and “clothes.”)

    “We can treat each particle like a word in a sentence,” Nguyen says.

    Currently, scientists are working with only a few signatures for Higgs-boson pairs, but they hope to study more complex signatures over the next few years.

    “This research is still in the early stages but moving very fast,” Lu says.

    https://www.symmetrymagazine.org/article/searching-for-higgs-boson-twins?utm_source=main_feed_click&utm_medium=rss&utm_campaign=main_feed&utm_content=click

    ( Feed URL: http://www.symmetrymagazine.org/feed )

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  • Astronomy Picture of the Day for 2021-02-25 12:30:02.453590

    Astronomy Picture of the Day (Unofficial) at 2021-02-25T18:30:03Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2021 February 25
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    A Venus Flyby
    Image Credit: NASA, JHUAPL, Naval Research Lab, Guillermo Stenborg and Brendan Gallagher

    Explanation: On a mission to explore the inner heliosphere and solar corona, on July 11, 2020 the Wide-field Imager on board NASA's Parker Solar Probe captured this stunning view of the nightside of Venus at distance of about 12,400 kilometers (7,693 miles). The spacecraft was making the third of seven gravity-assist flybys of the inner planet. The gravity-asssist flybys are designed to use the approach to Venus to help the probe alter its orbit to ultimately come within 6 million kilometers (4 million miles) of the solar surface in late 2025. A surprising image, the side-looking camera seems to peer through the clouds to show a dark feature near the center known as Aphrodite Terra, the largest highland region on the Venusian surface. The bright rim at the edge of the planet is nightglow likely emitted by excited oxygen atoms recombining into molecules in the upper reaches of the atmosphere. Bright streaks and blemishes throughout the image are likely due to energetic charged particles, and dust near the camera reflecting sunlight. Skygazers from planet Earth probably recognize the familiar stars of Orion's belt and sword at lower right.

    Tomorrow's picture: fly over


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