Have a deep view into what people are curious about.

🔗 Biography 🔗 New York City 🔗 Biography/science and academia 🔗 Anthropology 🔗 Anarchism

David Rolfe Graeber (; February 12, 1961 – September 2, 2020) was an American anthropologist, anarchist activist, and author known for his books Debt: The First 5000 Years (2011), The Utopia of Rules (2015) and Bullshit Jobs: A Theory (2018). He was a professor of anthropology at the London School of Economics.

As an assistant professor and associate professor of anthropology at Yale from 1998 to 2007, Graeber specialized in theories of value and social theory. Yale's decision not to rehire him when he would otherwise have become eligible for tenure sparked an academic controversy. He went on to become, from 2007 to 2013, reader in social anthropology at Goldsmiths, University of London.

His activism includes protests against the 3rd Summit of the Americas in Quebec City in 2001, and at the 2002 World Economic Forum in New York City. Graeber was a leading figure in the Occupy Wall Street movement, and is sometimes credited with having coined the slogan "we are the 99%". He accepted credit for the description "the 99%" but said that others had expanded it into the slogan.

🔗 New York City 🔗 Engineering

The Citicorp Center engineering crisis was the discovery, in 1978, of a significant structural flaw in Citicorp Center, then a recently completed skyscraper in New York City, and the subsequent effort to quietly make repairs over the next few months. The building, now known as Citigroup Center, occupied an entire block and was to be the headquarters of Citibank. Its structure, designed by William LeMessurier, had several unusual design features, including a raised base supported by four offset stilts, and diagonal bracing which absorbed wind loads from upper stories.

In the original design, potential wind loads for the building were calculated incorrectly. The flaw was discovered by Diane Hartley, an undergraduate student at Princeton University who was writing a thesis on the building, and was communicated to the firm responsible for the structural design. LeMessurier was subsequently lauded for acknowledging his error and orchestrating a successful repair effort. Estimates at the time suggested that the building could be toppled by a 70-mile-per-hour (110 km/h) wind, with possibly many people killed as a result. The crisis was kept secret until 1995 and Hartley had no knowledge of the significance of her work until after that time.

🔗 Biography 🔗 France 🔗 Middle Ages 🔗 Middle Ages/History 🔗 Biography/arts and entertainment 🔗 Christianity 🔗 Catholicism 🔗 Middle Ages/Crusades 🔗 Military history/Crusades 🔗 Belgium 🔗 Christianity/Christianity in China

William of Rubruck (Dutch: Willem van Rubroeck, Latin: Gulielmus de Rubruquis; fl. 1248–1255) was a Flemish Franciscan missionary and explorer.

He is best known for his travels to various parts of the Middle East and Central Asia in the 13th century, including the Mongol Empire. His account of his travels is one of the masterpieces of medieval travel literature, comparable to those of Marco Polo and Ibn Battuta.

Some observations on behavior on Wikipedia, interspersed with recommendations on how to deal with it.

1. When someone complains loudly about censorship, you may be certain they are up to no good.
2. Many people leaving the project blame either the project or the people working on it for their departure, rather than recognize that it is normal in life for one's enthusiasm to wane. It does with all things that we once found exciting. This is neither pessimistic nor tragic: one needs always to find new exciting things to do. All things in life change and end, and this includes one's involvement with Wikipedia. "He who kisses the joy as it flies / lives in eternity's sunrise." Enjoy it while you are here, and enjoy what you do after you have gone.
3. Troublesome editors waste far more of the community's time than vandals. One who sometimes makes good edits, but endlessly bickers, threatens, insults, whines, and is eventually banned, will have taken hundreds of hours from other users who would have better spent that time building the encyclopedia. This is in part due to people's fascination with conflict. Efficiently managing troublesome editors is one of the best ways to improve the project, but also one of the most difficult.
4. People who have the insatiable need to retaliate for perceived wrongs should be removed from the project as quickly, but gently, as possible.
5. Since mid-to-late 2005 there has been an increasing focus by Wikipedians, especially new Wikipedians, on designing pretty user pages, userspace widgets, fancy signatures, and other similar stuff rather than contributing content. This is probably not a good trend, but it is unlikely to change. The best content contributors often neglect these things, and vice versa.
6. Any logged-in user whose first edit is vandalism of a user page, or a nasty personal attack on a talk page, should be immediately and permanently blocked, without comment.
7. If a user's first and second edits are creations of their user and talk pages, devoid of content, their third edit will be vandalism, a personal attack, or another form of trolling. That people spring up to defend these accounts when they are blocked is neither complicity nor malice, but rather just inexperience.
8. Using an anonymous IP or creating a sockpuppet to vandalise a user page or leave a nasty personal attack is a particularly despicable form of cowardice. If you have a problem with someone, work it out in the open.
9. Single-topic editors are rarely, if ever, interested in or capable of NPOV. Additionally, if you look closely you will often find a conflict of interest.
10. The more extreme and unencyclopedic the viewpoint, the greater the likelihood of it attracting sockpuppet support.
11. If an editor is truly writing from a neutral point of view, it should be impossible to tell from that person's edits what their viewpoint is. This is most obvious in political articles, but applies everywhere.
12. Wikipedia is an encyclopedia. The primary job of Wikipedians is to write it. Everything else is secondary.
13. As the primary job of Wikipedians is to write the encyclopedia, any user whose principal activity is to interfere with the writing should be removed from the project, as painlessly as possible. The best way is to persuade them that they will be happier elsewhere, and to wish them well; the worst is to beat them up and make them angry: but however it happens, it must be done.
14. It is impossible to enumerate all the kinds of vanity. (La Rochefoucauld, No. 506)
15. Wikipedia's worst enemies are those whose vanity has been wounded. They may be moderately notable people who attempted to edit an article on themselves, and failed to control it; or they may be people who worked hard on an article on a subject about which they care, which was deleted by the community; or they may be people who attempted to push a POV which was rejected by the community. Usually they invoke a higher moral principle in support of their campaign against the project, such as censorship, free speech, conspiracy against them, or whatnot, as their own vanity prevents them from recognizing that vanity itself is the source of their displeasure.
16. Some trolls and POV-pushers are best fought with a time delay. Let them make their edit; then change it an hour or two later, or even the next day. Trolls are easily bored, and are more likely to go away if you hold your fire for a bit. (Blatant vandalism of course needs to be reverted immediately.) This tactic is especially useful with the Stormfront or Free Republic types, or versus any group that pushes a POV and is specifically looking for a fight.
17. There IS a cabal. It's a core group of editors united by the belief that the encyclopedia must protect itself against jerks, and against people who write junk.
18. As soon as someone attacks the community, or any portion of it, by writing a rant on their user page, Act V of their Wiki Tragedy has begun. It will end, inevitably, with their departure or expulsion from the project.
19. The Administrators' Noticeboards, RFC, RFArb, and occasionally RFA, are like galleries of spectacular freeway crashes, slowing traffic in both directions as everyone cranes their head around for a better view. Contributions to the encyclopedia decline every time there is a new wreck.
20. One of the less-noticed reasons for the increase in conflict in the project overall is that almost all of the articles on important subjects are written. There is less "exciting" work to do, such as creating from scratch an article on an important topic, and conflict is the most usual substitute excitement. The early days of the project are over, and just as in a relationship, the truly hard work comes after the initial excitement has faded.
21. There are no fools more troublesome than those with wit.
22. People who announce early in their Wiki careers that they want to be admins, probably shouldn't be. Adminship is better approached as a duty taken on by an established Wikipedian, than as a trophy for a newbie to aspire to. The best admins are those who are drafted, and not those who eagerly await a three-month threshold or a certain edit count. Adminship is not a trophy and beware those who want to pin it on like a shiny badge.
23. All the virtues and vices shown by humanity as a whole can be found on Wikipedia. Anyone who runs from the community because they cannot tolerate its vices, divisions, and politics, will have to face the same vices, divisions, and politics again elsewhere in life.
24. Anonymous edits to articles on traditional encyclopedic topics, especially during school hours, are far more likely to be vandalism than edits to popular culture topics.
25. Vandalism in the form of trolling and nasty personal attacks spikes on Friday and Saturday nights, local time. Look at the bright side: at least they're not driving drunk.
26. If a vandal insults you, it is a reliable indicator that you are doing something right.
27. One of the commonest kinds of vandalism is an assertion that something, someone, or somewhere is "gay". This is a reflection of the common, indeed unavoidable, sexual insecurity of male adolescents, who make up most of Wikipedia's vandals. It's as universal a part of maturing as acne; revert and ignore.
28. Any new article with exactly the same name as its creator can almost always be immediately deleted as CSD A7. "Userfying" – moving these pages to the new user's user page – is a slightly more compassionate approach, but it doesn't work as often as it should.
29. Good people leave the project all the time. Fortunately, good people join the project all the time as well. Bad people also come and go. The project survives in spite of all these arrivals and departures.
30. Many of our best contributors began with a few shabby edits. Be kind to newbies, even though it is a test of patience to see the same mistake hundreds of times over several years. Patience is one of the most underrated of the virtues, and in our present attention-deficit-disorder age it is one of the most rare.
31. People who loudly accuse the community of some vice are almost invariably guilty of, but blind to, some variant of that vice themselves.
32. If you've been blocked, consider first the possibility you did something wrong. Instead of complaining about abuse of power, censorship, or whatever, just behave in such a way that you don't get blocked. There are thousands of editors who have contributed enormously to Wikipedia without ever getting blocked. It's not that hard.
33. When someone's first edit is reverted, and they are sufficiently angered by this that they leave several paragraphs of invective on the reverter's talk page, it is highly unlikely that that person is suited to become a Wikipedia editor. Hard as it is, we need to leave our egos at the door, or as much of those egos as it is possible to unload. Not only can anyone edit, but anyone does edit, and reversions of good-faith edits are all part of a day's action here.
34. Whenever a group of people, particularly if they are administrators, gets together and agrees on something, there will inevitably be one or a handful of vocal detractors who oppose because they see something sinister in any group which is in agreement – especially if they perceive that group as having power over them. See WP:CABAL.
35. It's good to let your ego be punctured once in a while. Most of us, after several years and tens of thousands of edits, start to put a lot of our egos into our work here, more than we originally either intended or anticipated. While it's natural for this to happen, the unintended consequences include feelings of ownership over one's contributions and a quickness to react in poor faith, and even with arrogance. Someone reverted your edits with a sarcastic edit summary? Let it go. Someone called you a bad name somewhere? Don't retaliate. Let it go. While it hurts at first to let these things go, being able to do so is the true test of strength and maturity. You only gain in the long run. Retaliating not only brings you discredit, but it increases your anger, and corresponding risk of over-reaction, as the number of related provocations rises.
36. When you are angry, it is extraordinarily difficult to differentiate between a good-faith edit and the other kind. Postpone that decision until you are no longer angry. The consequences of reverting a good-faith edit with a vandalism-reversion tool or "rvv" edit summary are unpredictable, and unlikely to win you friends or trust. As a general rule, do not edit when you are angry. Wait until the feeling has passed, and you are yourself again.
37. When someone screams about "admin abuse", it's most likely true – they're probably abusing admins again. If there's a block involved, expect to see a battalion of sockpuppets in short order, making even more shrill cries of admin wrongdoing.
38. Try to be as tolerant as you possibly can regarding edits by established contributors. Should you need to revert one, leave as polite an explanation as possible, with room for compromise: and if they're simply wrong, don't rub their nose in it. The loss of long-established contributors due to avoidable conflict is one of the greatest threats the project faces. People who have been here a year or more, and made thousands of contributions to the project, are its greatest asset, and this cannot be overstated.
39. While it feels bad to be attacked by one of the persistent, nasty, obsessive trolls, it is helpful to remember that some of these people are profoundly miserable. They are really suffering; life is hell for them: often they are neither in control of their impulses, nor completely sane. A little compassion can help, although one's initial impulse is to strike back. Don't. It's a sign of strength not to retaliate, and a peaceful response may actually do some good.
40. "Retired" editors sometimes leave the project forever, especially if they have left out of weariness, or because it is no longer new, fun, and rewarding for them. If, however, they have left in anger, they may not leave permanently: expect to see them return for "revenge" against those they perceive to have done them wrong: and the actions they perform on their return are among the most vile in the project, and the least productive towards its ends. You can find this kind of behavior in greatest abundance at RFA, RFB, RFC, RFArb, and the noticeboards. Sometimes these disgruntled editors return as sockpuppets, but the braver come back under their own names: but as in all vendettas, they do more harm to themselves than their victims, for they only cover themselves in debasement and slime. No human behavior is more despicable than inflicting suffering just to feel good about it, but unfortunately this is a common motivation indeed.
41. As in the dry season arsonists start fires, so when there is a contentious event on Wikipedia, certain editors will attempt to escalate conflicts, and so enjoy their destructive course. You may recognize the same names appearing again and again in such circumstances. As I have said above, it has become harder to work on articles in the last few years, and it is much easier, and much more pleasurable, for some people to feel the rush and the pride in one's witty put-down of an opponent, than to write or cite or cleanup or reference an article that no one will immediately read. Conflict is as addictive as cocaine, and unfortunately Wikipedia's civility policies only limit incivility among those who respect them in the first place, and who have the personal strength not to need to retaliate. Anonymity is to cowardice what Viagra is to impotence.
42. A high proportion of Wikipedians have issues with authority. That's why many people are attracted to Wikipedia in the first place. Keep this in mind if you become an administrator, for you may have just become, unwittingly, what these people most resent; and no matter how good a job you do, they'll find your one mistake and beat you up with it. It's best just to accept this demographic for the reality it is. They are often our most capable content contributors, and as long as Wikipedia remains open to all, this situation will remain.
43. A related point is that Wikipedia is often accused of having a "liberal bias". The only bias it has arises from the self-selection of its members: people are here because they are the ones who want to contribute to an open-content project. You're going to get a lot of "libertarian left" here by the project's very nature.
44. When you are attacked by a troll, remember that their choice of insult says more about them than about you, and it's an opportunity for compassion. They just told you what hurts them, and obliquely what probably has, in the past. Harper Lee put it well in To Kill a Mockingbird: "...it's never an insult to be called what somebody thinks is a bad name. It just shows you how poor that person is, it doesn't hurt you..." My only quibble is this: while it might indeed hurt, it does no harm.
45. "Envy is more implacable than hatred." An often overlooked motivation for persistent harassment is that the troll wants something you have: recognition, passion, education, skill, knowledge – something. It's usually disguised by some claim of wrongdoing on your part, but the disguise often contains subtle hints that the troll wants acknowledgement as an equal. The more persistent the trolling, the higher the level of insecurity that the troll is unwittingly showing.
46. A useful two-question test, to apply to dodgy accounts that seem to be stirring up trouble: 1) Is this person helping to build the encyclopedia? 2) If not, is this person actively interfering with those of us who are? If the answers are "no" and "yes", respectively, block immediately and move on.
47. "And slime had they for mortar." Every place on earth has nationalists; they are the dupes of demagogues, the tools of conquerors, and a great pestilence upon Wikipedia. Write a thousand good words on an important but neglected figure, and a nationalist will show up to argue over the spelling of his name; his birthplace, ancestry, ethnicity, or category; all in a tone of moral outrage. Look at the "bright" side: they keep our friends in the war industry employed. When some day earth is hidden in its final radioactive dust-shroud, their ghosts will declare: it's not so bad, they got what they deserved. Let the sane among you ignore them, and be good citizens of all of mankind, rather than just an angry splinter of it.
48. People who put lists of editors they don't like on their user pages won't be around for long. See #18, as this is closely related.
49. The highest compliment a troll can pay to you is to create an attack page about you elsewhere on the internet. It's as close to an admission of surrender as you will get, in addition to showing that you are doing something very right indeed. As in on-wiki trolling, the insults they choose tell you more about them than about you. Consider such pages to be monuments to your good work, but otherwise ignore them.
50. Wikipedia is no more a place for people with control issues than mining is a career for claustrophobes. That such people are as common here as they are is a poignant reminder of the all-too-human tendency of the chronically disaffected to seek out environments that make them angry and miserable.
51. Beware lest you begin to enjoy too much the blocking of vandals, the crushing of trolls, and the banning of troublemakers; spend too much time ridding the project of monsters, you risk taking on the characteristics of those you drive off. Too much troll-fighting can be destructive for one's attention span, sensitivity, and taste. It should be no surprise that the most experienced at troll-fighting often have the shortest tempers. The best way to counter this tendency is to do other things regularly, such as having a life outside Wikipedia.
52. Trolls, banned editors, and mental defectives will try to annoy you, if you are an active contributor. Do good work anyway. Avenge yourself on your enemies by not becoming like them.
53. As sarcasm is the protest of the weak, so attack sites are the whining of the incompetent, who failed to succeed at editing Wikipedia. They are unimportant. Continue creating useful and beautiful things, and spread good will in the world; if others are consumed by hate and vindictiveness, you may feel compassion for them, and be grateful you are not so afflicted.
54. Nothing is harder to put up with than the annoyance of good example. If you want to be liked, screw up once in a while, and apologize.
55. We all think it's a good idea to stand up to bullies. Not only is it harder to do than you sometimes think, other than under the influence of testosterone or your anger-enhancer of choice, but in doing so you risk becoming a bully yourself. I quote from the Dalai Lama: "...when encountering injustice, take a strong stand – but with no ill intent."
56. As Freud observed, we are most courageous when we feel most loved. Conversely, the lonely are often the most craven, and their anger is the most vindictive. Wikipedia is filled with the lonely.
57. "The cut worm forgives the plow." Trolls and banned editors may harass you repeatedly, attempting to provoke a reaction. Let it go; they'll get over it. The plow already has.
58. Beware of users so in love with their own virtue, that they are incapable of recognizing when it has become vice; and so in love with their own eloquence, that they cannot see when it has become hypocrisy. The former are those who never admit to any wrong, but yet demand apologies from others for the lapses of judgement to which all human beings are prone; and the latter are the blindest and most intractable of POV-pushers. Skill with words correlates neither with virtue nor wisdom.
59. When an editor ceases to contribute to articles, but instead writes only in the Wikipedia space, on talk pages, and arbitration cases, and when more than half of that editor's contributions are in conflicts, either beginning or prolonging them, then that editor is very close to departure. As with stars on the main sequence, some departures are shrinkings into dwarf states, with ever-diminishing contributions, giving little light, and with a long decay; and other departures are violent supernova explosions, spewing waste matter and hot gas in all directions.
60. It is easier to get a sincere "thank you" for reverting "you're a faggot" from someone's userpage, than it is for writing a researched, thorough, and referenced encyclopedia article on an encyclopedic topic. The best way to continue as a writing Wikipedian for many years is to be, as the Buddha recommends, "indifferent to both praise and blame." Indifference to praise is a hard task for mere humans, but millions of potential anonymous readers demand it of you, for if you require praise you will burn out with one of the fates indicated in No. 59. And remember this: you are allowed to take your work seriously here, and think highly of your own efforts; but be advised, don't talk about it.
61. When Wikipedians spend too much time on the noticeboards, in Arbcom cases, and on talk pages of contentious articles, they have a high probability of concluding that Wikipedia is dysfunctional, incompetent, and doomed to fail. Once a Wikipedian has reached this realization, expect that person's user page to boast an essay announcing the imminent failure of the project. The best cure for this condition is to leave those places, and instead read a few articles on genuinely encyclopedic topics, noticing just how good they actually are. Similarly, if you were to look at a table at a subatomic level, you would see that it consists mainly of empty space, with innumerable minuscule particles whizzing about angrily, each having an arbitrary and undefinable position; indeed, if you look at them too closely, they will change just to spite you: but back away, the whole becomes visibly a table again. We're a pretty good encyclopedia, and you will notice it once you back away from the conflict zones.
62. There will be world peace, and the lion will lie down with the lamb, before banned users realize that they have only themselves to blame for being banned. All campaigns referencing "corrupt admins" and "cabals" arise from this same inexhaustible source of folly: I can't possibly be wrong – all of them must be.
63. That bad editors seem to be as large and troublesome a group as they are is a form of selection bias, and the more time you spend on noticeboards, the worse it seems. It's rather like the bad drivers you encounter on the roadways: when you reach your destination, you may remember the two or three bad drivers you encountered, but not the hundreds of good ones who escaped your attention by doing everything right. Thus there may be 99 good editors for every bad one, but you'd never notice, for their names do not appear in drama threads, and their angry messages never contaminate your talk page.
64. Playing the victim makes you smaller. This is something that returning banned users, on making their shrill accusations of cabals and conspiracies and personal vendettas, do not realize: it does not make them rise in importance – it shrinks them, diminishes them, makes them even more insignificant and ridiculous on each iteration. It's reminiscent of Richard Matheson's Incredible Shrinking Man, that great existential film into which so much can be read. Instead of helping build the largest encyclopedia in the history of the human race, those trolls finish their Wiki lives battling imagined spiders, with toothpicks.
65. The only one-hundred-percent certain way to get rid of a troll is to close the browser tab. Takes a mouse click. Hard to do though, isn't it?
66. Any edit that improves the encyclopedia is a good edit. Before clicking "save page", always run this through your final mental checker: does what I just did in that edit box improve the encyclopedia?
67. People still write new articles for the encyclopedia, but with all the sound and fury at the noticeboards, you have to go out of your way to notice. Even more important, you have to care.
68. It's easier to burn down a dilapidated building than to fix it. The bigger the ego, the more pyromaniacal the impulse.
69. When you realize that editing an article on a current world conflict stresses you out more than the actual conflict does, it is time to take a break. Having your edits bombed to oblivion with an rvv is not as bad as losing your entire family to a paramilitary raid, and sometimes it is important to think about it.
70. It is impossible to love again anything you have truly ceased to love. Editors who return after retirement, or after a wearied or bitter departure, may edit again, but never with the same passion they once brought to the project. Each successive return will be with diminished dedication and shorter duration.
71. The very existence of Wikipedia is a massive proof that there are more people in the world wanting to build than to tear down. Were that not true, vandals would have overwhelmed and destroyed us years ago.
72. "Truth" is a big word. Editors who make abrupt claims about either having, knowing, or insisting on "truth", and editors who include the word in their usernames, are probably doing something that does not belong in an encyclopedia; and the more stridently they argue, the more suspicious you are right to be.
73. A common insult hurled at dedicated Wikipedia editors is that they "have no life". If you write extensively in an out-of-the-way area, you may well become the most widely read writer in the world on your topic. There are worse ways of "having no life", such as abusing the few actually useful people on the internet, but those who deliver such insults are invariably tone-deaf to irony.
74. The more one hates, the less one cares about what is true. This is as true in politics as with obsessed sockpuppeteers, and it's the secret sauce in conspiracy theories: look carefully at any, and you’ll find hatred at its core.
75. We have a noticeboard for everything imaginable, except competence.
76. Beware that moment when you think yourself wise, for you may have just become a fool.

I'm as prone to vanity as anyone, if not more so, and posting these observations is not an attempt to imply that I am above these behaviors myself.

🔗 Physics 🔗 Astronomy

In astrophysics and physical cosmology, Olbers' paradox, named after the German astronomer Heinrich Wilhelm Olbers (1758–1840), also known as the "dark night sky paradox", is the argument that the darkness of the night sky conflicts with the assumption of an infinite and eternal static universe. In the hypothetical case that the universe is static, homogeneous at a large scale, and populated by an infinite number of stars, then any line of sight from Earth must end at the (very bright) surface of a star and hence the night sky should be completely illuminated and very bright. This contradicts the observed darkness and non-uniformity of the night.

The darkness of the night sky is one of the pieces of evidence for a dynamic universe, such as the Big Bang model. That model explains the observed non-uniformity of brightness by invoking spacetime's expansion, which lengthens the light originating from the Big Bang to microwave levels via a process known as redshift; this microwave radiation background has wavelengths much longer than those of visible light, so appears dark to the naked eye. Other explanations for the paradox have been offered, but none have wide acceptance in cosmology.

🔗 Chemicals 🔗 Molecular and Cell Biology 🔗 Evolutionary biology

Evolution of metal ions in biological systems refers to the incorporation of metallic ions into living organisms and how it has changed over time. Metal ions have been associated with biological systems for billions of years, but only in the last century have scientists began to truly appreciate the scale of their influence. Major (iron, manganese, magnesium and zinc) and minor (copper, cobalt, nickel, molybdenum, tungsten) metal ions have become aligned with living organisms through the interplay of biogeochemical weathering and metabolic pathways involving the products of that weathering. The associated complexes have evolved over time.

Natural development of chemicals and elements challenged organisms to adapt or die. Current organisms require redox reactions to induce metabolism and other life processes. Metals have a tendency to lose electrons and are important for redox reactions.

Metals have become so central to cellular function that the collection of metal-binding proteins (referred to as the metallomes) accounts for over 30% of all proteins in the cell. Metals are known to be involved in over 40% of enzymatic reactions, and metal-binding proteins carry out at least one step in almost all biological pathways.

Metals are also toxic so a balance must be acquired to regulate where the metals are in an organism as well as in what quantities. Many organisms have flexible systems in which they can exchange one metal for another if one is scarce. Metals in this discussion are naturally occurring elements that have a tendency to undergo oxidation. Vanadium, molybdenum, cobalt, copper, chromium, iron, manganese, nickel, and zinc are deemed essential because without them biological function is impaired.

🔗 Musical Instruments 🔗 Percussion

Campanology () is the scientific and musical study of bells. It encompasses the technology of bells – how they are founded, tuned and rung – as well as the history, methods, and traditions of bellringing as an art.

It is common to collect together a set of tuned bells and treat the whole as one musical instrument. Such collections – such as a Flemish carillon, a Russian zvon, or an English "ring of bells" used for change ringing – have their own practices and challenges; and campanology is likewise the study of perfecting such instruments and composing and performing music for them.

In this sense, however, the word campanology is most often used in reference to relatively large bells, often hung in a tower. It is not usually applied to assemblages of smaller bells, such as a glockenspiel, a collection of tubular bells, or an Indonesian gamelan.

🔗 Iran 🔗 Alternative Views 🔗 Iraq

The Baghdad Battery or Parthian Battery is a set of three artifacts which were found together: a ceramic pot, a tube of copper, and a rod of iron. It was discovered in modern Khujut Rabu, Iraq, close to the metropolis of Ctesiphon, the capital of the Parthian (150 BC – 223 AD) and Sasanian (224–650 AD) empires of Persia, and it is considered to date from either of these periods.

Its origin and purpose remain unclear. It was hypothesized by some researchers that the object functioned as a galvanic cell, possibly used for electroplating, or some kind of electrotherapy, but there is no electroplated object known from this period. An alternative explanation is that it functioned as a storage vessel for sacred scrolls.

🔗 Iran 🔗 Classical Greece and Rome 🔗 Dams 🔗 Bridges and Tunnels

The Band-e Kaisar (Persian: بند قیصر, "Caesar's dam"‎), Pol-e Kaisar ("Caesar's bridge"), Bridge of Valerian or Shadirwan was an ancient arch bridge in Shushtar, Iran, and the first in the country to combine it with a dam. Built by the Sassanids, using Roman prisoners of war as workforce, in the 3rd century AD on Sassanid order, it was also the most eastern example of Roman bridge design and Roman dam, lying deep in Persian territory. Its dual-purpose design exerted a profound influence on Iranian civil engineering and was instrumental in developing Sassanid water management techniques.

The approximately 500 m long overflow dam over the Karun, Iran's most effluent river, was the core structure of the Shushtar Historical Hydraulic System (سازه‌های آبی شوشتر) from which the city derived its agricultural productivity, and which has been designated by the UNESCO as Iran's 10th World Heritage Site in 2009. The arched superstructure carried across the important road between Pasargadae and the Sassanid capital Ctesiphon. Many times repaired in the Islamic period, the dam bridge remained in use until the late 19th century.

🔗 Physics 🔗 Astronomy 🔗 Chemistry 🔗 Water 🔗 Astronomy/Solar System

Superionic water, also called superionic ice or ice XVIII, is a phase of water that exists at extremely high temperatures and pressures. In superionic water, water molecules break apart and the oxygen ions crystallize into an evenly spaced lattice while the hydrogen ions float around freely within the oxygen lattice. The freely mobile hydrogen ions make superionic water almost as conductive as typical metals, making it a superionic conductor. It is one of the 19 known crystalline phases of ice. Superionic water is distinct from ionic water, which is a hypothetical liquid state characterized by a disordered soup of hydrogen and oxygen ions.

While theorized for decades, it was not until the 1990s that the first experimental evidence emerged for superionic water. Initial evidence came from optical measurements of laser-heated water in a diamond anvil cell, and from optical measurements of water shocked by extremely powerful lasers. The first definitive evidence for the crystal structure of the oxygen lattice in superionic water came from x-ray measurements on laser-shocked water which were reported in 2019.

If it were present on the surface of the Earth, superionic ice would rapidly decompress. In May 2019, scientists at the Lawrence Livermore National Laboratory (LLNL) were able to synthesize superionic ice, confirming it to be almost four times as dense as normal ice and black in color.

Superionic water is theorized to be present in the mantles of giant planets such as Uranus and Neptune.