Academics From The United States

"Let F be a field of characteristic 0, and let F be a finite dimensional vector space over F. Let E denote the algebra of all endomorphisms of V, and let L be any Lie subalgebra of E. Among the algebraic Lie algebras contained in E and containing L, there is one that is contained in all of them, and this is called the algebraic hull of L in E. Here, an algebraic Lie algebra is defined as the Lie algebra of an algebraic group. It is an easy consequence of the definitions that if A and B are algebraic groups of automorphisms of V such that A⊂B then the Lie algebra of A is contained in the Lie algebra of B. Hence the existence of the algebraic hull of L is an immediate consequence of the following basic result: let G be the intersection of all algebraic groups of automorphisms of V whose Lie algebras contain L."

"A Lie algebra is said to be algebraic if it is isomorphic with the Lie algebra of an affine algebraic group. In view of the fact that entirely unrelated affine algebraic groups (typically, vector groups and toroidal groups) may have isomorphic Lie algebras, this notion of algebraic Lie algebra calls for some clarification. The most relevant result in this direction is due to M. Goto. It says that a finite- dimensional Lie algebra L over a field of characteristic 0 is algebraic if and only if the image of L under the adjoint representation is the Lie algebra of an algebraic subgroup of the group of automorphisms of L ..."

"... Lie algebras have a significance reaching beyond the domain of algebra, because they play such an important role in the theory of Lie groups. Thus, classical Lie algebra theory is strongly dominated by the fact that the finite-dimensional analytic representations of a simply connected analytic group are identifiable with the finite-dimensional representations of its Lie algebra. In the theory of infinite-dimensional representations, the connection with Lie algebra representations is somewhat tenuous, but it is nevertheless at the core of the major advances made in that theory during the last 30 years."

"To judge from what he has to say about the past, he is unlikely to lose sleep over presidential abuses of power in the present or future. Indeed, Gaddis admonishes Americans for placing restrictions on their elected rulers. Describing what he clearly sees as the regrettable overreaction to Watergate and Vietnam in the 1970s, he writes: “The United States Congress was passing laws—always blunt instruments—to constrain the use of United States military and intelligence capabilities. It was as if the nation had become its own worst enemy.” Retrospectively frustrated by such constraints, Gaddis admires the boldness and vision of President George W. Bush. A keen supporter of the recent Iraq war, Gaddis in 2004 even published a guide for the use of American policymakers, showing how preemptive and preventive war making has an honorable place in American history and is to be encouraged—where appropriate—as part of an ongoing project of benevolent interventionism. Thus, while it may seem tempting to dismiss John Lewis Gaddis’s history of the cold war as a naively self-congratulatory account that leaves out much of what makes its subject interesting and of continuing relevance, that would be a mistake. Gaddis’s version is perfectly adapted for contemporary America: an anxious country curiously detached from its own past as well as from the rest of the world and hungry for “a fireside fairytale with a happy ending.” The Cold War: A New History is likely to be widely read in the U.S.: both as history and, in the admiring words of a blurb on the dust jacket, for the “lessons” it can teach us in how to “deal with new threats.” That is a depressing thought."

"No one can be certain where or when the next great earthquake will occur. It is helpful to know, though, that such upheavals take place more frequently in California than in Kansas: that people who live along the San Andreas Fault should configure their houses against seismic shocks, not funnel clouds. Nobody would prudently bet, just yet, on who will play in the 2001 World Series. It seems safe enough to assume, though, that proficiency will determine which teams get there: achieving it, too, is a kind of configuring against contingencies. Not even the most capable war planner can predict where the next war will occur, or what its outcome will be. But is it equally clear that war planning should therefore cease? The point, in all of these instances, is not so much to predict the future as to prepare for it."

"Learning about the past liberates the learner from oppressions earlier constructions of the past have imposed upon them."

"The Cold War could have produced a hot war that might have ended human life on the planet. But because the fear of such a war turned out to be greater than all of the differences that separated the United States, the Soviet Union, and their respective allies, there was now reason for hope that it would never take place."

"Both the United States and the Soviet Union had been born in revolution. Both embraced ideologies with global aspirations: what worked at home, their leaders assumed, would also do so for the rest of the world."

"Stalin's postwar goals were security for himself, his regime, his country, and his ideology, in precisely that order."

"The world of the was a wonderfully diverse and pluralistic world, and nowhere is that diversity and pluralism seen more clearly than in the text of ritual power that were produced and used by the people who inhabited that world."

"Through the history of the modern academic and culture, as we have noted, the definition of "magic" in relation to science and religion has been a major problem. At the root of the problem is the loaded, evaluative of "magic" as false, deceptive, discredited, or morally tainted, contrasted with both science (a correct, enlightened understanding of natural law and causation) and religion (a correct, enlightened understanding of the divine and spirituality). Thus, "magic" is relegated to the "they" side of a "we/they" . This is simultaneously unfair to the materials and practices studied under the heading of "magic," and self-serving for the materials (mainly those we identify as "our own") that are exempted from that label. It perpetuates a complacent ."

"The exposition or exhibition and fair are primarily for the promotion of industry and commerce; the museum for the development of learning."

"It was my greatest good fortune to serve under Doctor George Brown Goode whose influence on the museums of America may be compared to that of Flower on the museums of England. Like Flower, he early recognized the educational possibilities of museums and the importance of making them interesting and attractive to the general public. One of his favorite maxims was to keep ever in mind the human interest in any exhibit, to show just where and how it touched man directly. And under his direction, the U. S. National Museum, and the various exhibitions in which it took part, exerted a great influence on the museums of the country and particularly on those that came into existence after 1880."

"The Trump administration has fired the state department’s inspector general who is reported to have been investigating the secretary of state, Mike Pompeo, for a potential abuse of office. The inspector general, Steve Linick, was given notice of his dismissal late on Friday night and is to be replaced by Stephen Akard, a close ally of the vice-president, Mike Pence... According to a Democratic congressional aide, just before his abrupt dismissal Linick had opened an investigation into allegations that Pompeo had been using a political appointee at the state department to run personal errands for him and his wife, Susan. Linick is the latest in a string of officials in watchdog roles fired by the president in recent months, turning on its head the tradition that such jobs are filled with non-partisan figures... In 2019 a state department whistleblower reportedly alleged that Pompeo had used his security detail to run chores like picking up food and picking up the family dog from the grooming salon. Under US law the president is required to give 30 days’ notice before firing an inspector general, to allow Congress to investigate the reasons for dismissal."

"The assault on the IG is late-stage corruption, and Trump’s kicking down one of the last bulwarks that stand between us and the burgeoning corruption-driven authoritarianism.... Cover it like you’re a foreign correspondent in a collapsing republic. Because you are. (to journalists)"

"With the Renaissance came a period of new life for collectors. The churches of southern Europe became art galleries, and monarchs and noblemen and ecclesiastical dignitaries collected books, manuscripts, sculptures, pottery, and gems, forming the beginning of collections which have since grown into public museums. Some of these collections doubtless had their first beginnings in the midst of the dark ages, within the walls of feudal castles, or the larger monasteries, but their number was small, and they must have consisted chiefly of those objects so nearly akin to literature as especially to command the attention of bookish men."

"Let’s be clear: all of these moves are punishment for doing the jobs the law authorizes and requires IGs (inspectors general) to do... This will not end until Congress takes these retaliatory firings seriously. The appointment of a crony of the VP further politicizes jobs that by statute are supposed to be non-partisan. Another important norm defiled."

"This firing is the outrageous act of a president trying to protect one of his most loyal supporters, the secretary of state, from accountability... I have learned that the Office of the Inspector General had opened an investigation into Secretary Pompeo. Mr Linick’s firing amid such a probe strongly suggests that this is an unlawful act of retaliation.”"

"John Podesta, the chairman of Hillary Clinton’s presidential campaign, says there are “serious questions” about the integrity of the State Department Office of Inspector General (OIG). The OIG is locked in an increasingly contentious fight with Clinton’s campaign on a host of issues, including her use of a private email account during her time as secretary of State... source within the OIG contacted The Hill claiming that the office has grown increasingly partisan, accusing it of having an “anti-Clinton” bias. Told by The Hill about the remarks, Podesta described the source as a “whistleblower” whose comments called into question the integrity of the OIG investigations. “This person’s account is highly troubling, and is cause to ask serious questions about the independence of this office,” Podesta said of the source. The Clinton campaign says it does not know the identity of the source. An OIG official strongly disputed the source’s account. “Partisan politics play no role in OIG’s work,” the spokesman said Monday. The source charges that State Inspector General Steve Linick is “excessively deferential” to Emilia DiSanto, the OIG deputy director and a former aide to Senate Judiciary Committee Chairman Chuck Grassley (R-Iowa)... The source also charged that Linick is “more or less under her control, possibly out of a desire for a more prestigious appointed position.” ... The OIG spokesman noted that Linick, a two-time appointee of President Obama, was asked by Secretary of State John Kerry last year to investigate how the department handles records management, Freedom of Information Act (FOIA) requests and the archiving of emails."

"The State Department’s official watchdog is finalizing several investigations into the Trump administration’s alleged mistreatment of its workforce, its top auditor told lawmakers on Thursday. State’s inspector general is wrapping up an 18-month probe into alleged prohibited personnel practices by the department’s political appointees at two different offices. Department whistleblowers told lawmakers in early 2018 they were being assigned to tasks unrelated to their normal, substantive duties because of work they had conducted under the Obama administration. Investigators have opted to deliver two separate probes, one looking at potential misconduct at the Bureau of International Organizations and the other in the Office of the Secretary, Steve Linick, the IG, told the House Appropriations Committee. Linick opted to separate them so the could deliver the results of the international office investigation to State this week. He expected to complete the probe into the secretary’s office next month. Both reports will be made public after State has the opportunity to review and respond to them."

"Inspector General Steve Linick recommended that the department develop a “corrective action plan” to fix the leadership deficiencies in the bureau. He also recommended that the department consider other moves, including “disciplinary action” against (Kevin) Moley. The State Department has agreed on both counts. Linick has been investigating allegations that Trump appointees had targeted career staffers for political retaliation since spring 2018. His other cases include ones involving the alleged actions of aides to former Secretary of State Rex Tillerson. They include one case exposed by Politico in which a career staffer of Iranian descent was ousted from a top policy role. Linick’s investigation grew to cover the international organizations bureau after a June 2018 report in Foreign Policy about (Mari) Stull, whom career staffers accused of deeply hostile behavior, including compiling loyalty lists. The report issued on Thursday is based on thousands of emails and other documents, as well as investigators’ interviews with more than 40 people, including Deputy Secretary of State John Sullivan. Secretary of State Mike Pompeo is not listed as having been interviewed. “Nearly every employee interviewed by OIG raised concerns about the leadership of IO and the treatment of staff,” the report states."

"We want to make sure we get it right... We want it to be accurate and thorough. It’s a top priority for our office...There is evidence that it (unfilled vacancies) has affected staffing, for example, in consular operations. It has affected staffing in bureau of diplomatic security, which obviously affects our security if we have limited staff. It’s affected our IT staff...we have not recovered yet in our civil service staffing levels at this point.... (the hiring freeze’s impact on the existing workforce) does have an impact on morale around the world... Inexperienced staff, insufficient training, staffing gaps and frequent turnover contribute to the department’s other management and performance challenges."

"At a minimum, Secretary Clinton should have surrendered all emails dealing with Department business before leaving government service and, because she did not do so, she did not comply with the Department's policies that were implemented in accordance with the Federal Records Act (From Linicks's May 2016 report)"

"Steve Linick, the State Department's inspector general, is set to hold an "urgent" briefing Wednesday with senior congressional staff members after Secretary Mike Pompeo Tuesday accused lawmakers of "intimidating and bullying" State Department officials by calling them for depositions related to the Ukraine inquiry... Although Linick serves at the pleasure of the President, there are safeguards to prevent him from being quickly removed... Linick, who was appointed to his post in September 2013 has a history of serving in oversight positions. At the State Department he oversaw the investigation into former Secretary of State Hillary Clinton's use of a private email server. His May 2016 report on the probe was critical of Clinton, saying the former secretary failed to follow the rules or inform key department staff regarding her use of the private server."

"Linick previously served as inspector general of the Federal Housing Finance Agency from 2010 until 2013. He was also an assistant US attorney in California and Virginia. Linick served as executive director of the Department of Justice's National Procurement Fraud Task Force as well as deputy chief of the fraud section in the DOJ Criminal Division from 2006 to 2010. During his tenure at the Department of Justice, he supervised and participated in white-collar criminal fraud cases involving, among other things, corruption and contract fraud against the U.S. in Iraq and Afghanistan," according to his State Department biography."

"Steve Linick, who was appointed to detect mismanagement at the state department, was fired on Friday. US Democrats have launched an investigation into President Donald Trump's firing of the state department's internal watchdog. Inspector General Steve Linick was investigating Secretary of State Mike Pompeo for suspected abuse of office, reports say. But he was sacked late on Friday after Mr Trump said he no longer commanded his full confidence. The move prompted angry criticism from senior Democrats in Congress. They accused Mr Trump of retaliating against public servants who want to hold his administration to account. Mr Linick was the third official responsible for monitoring government misconduct to be dismissed in recent weeks."

"The decline of Buddhism in India was not a singular event, with a singular cause; it was a centuries-long process that unfolded in a patchwork. The seeds of Buddhism’s decline began in the mid-first millennium ce, when the sangha began withdrawing into their monasteries and divorcing them-selves from day-to-day interactions with the laity. Into this spiritual void stepped Hindu and Jain sects, who revamped their ritual practices and religious architecture to more closely resemble traditional Buddhist practices. In the South and West of India, Hindu and Jain sects increasingly earned the support of the political and economic elite. In the Western Ghats, the last major Buddhist temples were constructed at Ellora in the seventh and eighth centuries CE. Across South India, the sangha aban-doned Buddhist sites, many of which were later reoccupied by Hindus and Jains. While some small Buddhist centers still persisted in South and West India in the eleventh and twelfth centuries, for the most part, both monastic and lay Buddhism had been eclipsed and replaced by Hinduism and Jainism by the end of the first millennium CE."

"There is an invaluable treasure trove of useful historical data that has only just begun to be used to inform our actions. The lessons of 1918 (Spanish flu), if well heeded, might help us to avoid repeating the same history today (COVID-19)."

"I used [Paco's] heart model... as my guide, to place pacemaker electrodes through a location on top of the septum... to reach the natural conducting system. The twisting motion was immediately reproduced to create normal heart performance! This approach was applied to over 700 patients around the world... and yielded similarly positive outcomes. Yet conventional cardiac approaches have not changed. Why..? Manufacturers would need to produce new types of pacemakers... Cardiologists would need to learn new techniques... Acquiring proficiency... is a little harder at first, but once learned, requires only 20... minutes of added [surgery] time."

"I have a way of looking at things, because I discover failure and find solutions. ...I'm grateful that I've been able to implement medical care that's given, but realize there are major limitations, major failures... I have spent... fifty years finding solutions to many of those different problems."

"[T]he age-old obstacle to growth, it's called rigidity. ...When you talk about... finding an answer, proving it, and nobody uses it. A book called ' by ... it was about... who worked in a maternity ward and found that many women after they gave birth... would die. ...He found the women that lived were delivered by the wet nurses and the women that died were delivered by the doctors... He realized that the doctors that would deliver the babies, go across the street [and] do an autopsy, but there's no germ theory. The doctors would wipe off their hands, and go back and infect the women. ...[H]e said, what you have to do is to wash your hands. He told the Titans of medicine. They still exist today. All these Titans of medicine that know everything, that you're doing it wrong. ...[T]hey didn't listen to him but eventually... it did win, it was right, because truth always wins."

"[P]acemakers elevate the heart rate... but they don’t always reproduce a normal heartbeat. ...[I]f the pacemaker leads are placed directly in ventricular muscle... the natural electrical system is not utilized. ...[T]here is loss of the natural twisting motion needed for efficient contraction. It may even cause heart function to worsen and produce heart failure in patients with dilated hearts. In other patients, fatigue will not improve, and shortness of breath will not get better."

"What Dr. Buckberg and I did for 35 years is, we looked at... ischemia reperfusion... What Gerry and I did for all of that time was to look at how can we avoid that injury. How can we let those cells repair themselves rather than being damaged with reperfusion? ...How do we protect the heart? Because every heart surgery, or the majority of them, you have to stop the heart so we can operate... while it's not having blood supply and while it's not beating. That means... you may have a reperfusion injury... [S]olutions that Dr. Buckberg pioneered probably helped save more people that any surgeon alive, because those solutions protect the heart. But we took it to the next levels because there are a lot of diseases like heart attacks... nothing more than a part of the heart gets no blood supply, and that part eventually dies. A stroke... transplants where we take organs out and they're ischemic. ...[W]e apply that concept to these other things. ...If we have a patient that has a heart attack... the cardiologist... will open up the artery, and suddenly the blood goes in there and the patient's pain goes away... but they've still killed that area of the heart. ...What we would recommend is... avoiding that reperfusion injury. ...[T]hose patients with some of this dead muscle, 1/3 - 40% of them will go into heart failure... 4 to 5 years later... which is a huge cost to society."

"[O]ne of the great anguishes in medicine is its inability to treat right (ventricle) heart failure... [due to] an absence of understanding how the normal right ventricle... functions. Conventional views hold... a 400-year-old belief that the right ventricle compresses like "a "... But... that... only accounts for 20% of the... pumping... The shortening of the septum... produces 80% of its function. ...Torrent-Guasp’s "helix and wrap"... model clarifies why... [m]odern 3-D imaging confirms that the septum portion of the helix... twists to pump... from the right ventricle to the lungs... In animal testing, we further verified [this]."

"Clearly it’s important not to injure the septum during operations. So why is it happening repeatedly? ...[L]ikely ...improper myocardial protection (the technique used to protect the heart... that was my initial major medical discovery and quickly adopted worldwide). We... tested 119 consecutive patients and found no septum damage when protection was done correctly. ...Successful protection involves ...the cardioplegic solution and adopting a correct delivery strategy. ...[I]f surgeons are to prevent the all-too-frequent injury to the heart’s vital septum, they must avoid taking shortcuts that compromise this essential combination."

"In managing heart failure in dilated hearts, we must recognize its cause is flawed heart anatomy... normality is restored after rebuilding the natural cardiac form."

"Paco Torrent-Guasp’s revelation of the heart’s authentic structure finally explains... stretching (dilation) during heart failure causes the heart’s normal elliptical shape (like a football) to become spherical (like a basketball). This geometric alteration rearranges the heart muscle pathways so the natural helix figure-eight pattern now becomes horizontal. ...[T]he spherical heart loses its normal ability to twist, which markedly reduces its contraction power, causing fatigue and breathlessness. ...Conventional treatments that only remedy diseased narrowed arteries or leaky valves do not restore... function correctly. ...Normality can only be returned by restoring the... shape... Paco’s helical heart... became my guide, leading to a new procedure called "Pacopexy"... [achieving] functional improvement... not... possible without... ventricular restoration to rebuild normality."

"Fifty percent of [heart] failures are caused by poor contraction of the ventricle (systolic dysfunction) that pumps blood... But the other half have poor filling (diastolic dysfunction) of blood into the ventricle... despite... normal heart contraction. ...[T]here has been uncertainty in how to treat diastolic dysfunction because its mechanical causes have been unknown."

"Surgical Ventricular Restoration was successfully tested internationally in 1200 patients. Instead of the [typical] 50-to-75% two-year death rate... this surgical treatment showed a 70% five-year survival, with a return to near normal heart function and only very rare occurrences of dangerous ventricular rhythms. Sadly, a faulty NIH-funded study of this groundbreaking treatment utilized physicians who were not qualified... disregarded proper selection of patients, and incorrectly performed procedures. Its erroneous findings led to... abandonment... despite a report that supports this treatment... Its dismissal... is tragic, and leads to enormous and unnecessary suffering upon... millions"

"It is universally believed that just five minutes or more of no blood flow to the brain is always lethal. We had already verified that controlled reflow of blood after a heart attack (adding specific chemical ingredients...) returns healthy cardiac function. We tested if a similar recovery could occur in the brain... and showed an astounding return of complete brain function after 30 minutes of no brain blood flow! ...Yet ...the NIH rejected our request for funding to study this further. They... deemed this... as "not interesting.""

"[O]ur lab studies on test subjects... implied that while CPR plays a positive role in treating witnessed arrest (when applied quickly once the heart stops beating)... application of CPR in unwitnessed arrest (when there is a delay before its use) is... wrong... because after the brain has been ischemic... CPR will return normal blood to the brain. ...Yet medicine continues endorsing this approach—despite the 99% mortality."

"Our findings could lead to radical changes in protocol, in which CPR is not immediately applied in unwitnessed arrest, and other techniques are used instead... [to] include using controlled reflow (adding specific chemical ingredients...) ...additional lab studies suggest this new... approach could possibly lead to treatments for stroke victims that avoid brain injury, since the same extended period of insufficient blood flow to the brain occurs... [T]here are 700,000 stroke victims annually in the United States alone. Further funding and research... are vitally needed."

"Understanding Paco’s "helix and wrap" structure solves this problem. ...[W]e found that suction accounts for most of filling (70%)... during the first 1/3 of the period when the heart relaxes... caused by how the figure-eight helix arms and its surrounding wrap interact. ...[W]hen the ventricle’s pumping ...during a heartbeat lasts longer than it is supposed to... [t]his shortens the available time for suction to fill... diastolic dysfunction develops. ...[W]e found ...calcium influences contraction and relaxation ... ...uniquely prevented calcium buildup. ...[T]he ...pharmacological trial ...failed after the manufacturer disregarded advice from the study’s steering committee. ...Diastolic dysfunction’s cause (helix and wrap dynamics) and curative drug (Cariporide) are neither taught in medical school, nor... known by... cardiologists..."

"Today, wonderful operations can be performed on babies to repair heart defects. This includes "blue babies." During the corrective procedure, high levels of oxygen are typically administered by a heart-lung machine... But... lung and heart damage may worsen. ...[O]ne cause of the problem were the high levels of oxygen administered ...as toxic substances are produced when such oxygen concentrations are metabolized. Babies are particularly vulnerable... Yet we found this "re-oxygenation injury" could be avoided by lowering oxygen levels delivered... There was excellent recovery of heart function without lung or body swelling. ...A 2012 overview on reoxygenation injury was published in the World Journal for Pediatric and Congenital Heart Surgery that summarized international papers from others... [R]aising such questions to traditionalists garners vehement rejection, along with counterarguments that keeping oxygen levels high is a strategy ..."proven..." over many decades (since not all blue babies suffer damage...) They perceive the greater risk is losing the baby because of "insufficient... oxygen"... and... blame... unforeseen complications on other factors."

"Conclusive answers are not gained by adhering to past beliefs or by assuming that what seems logical is valid. The answer is only revealed through investigation."

"Sudden death... cardiac arrest... occurs because the heart suddenly stops (having either no beat, or develops a totally ineffective beat such as ). CPR is typically performed... and if one is available, a defibrillator... restoring the heartbeat. Yet... the harsh reality is that 85 to 90% of these patients die, and severe brain damage develops in half of those who do survive. ...CPR, defibrillation ...does not address the heart defect ...[W]hy stay so stubbornly attached to a method in which 85 to 90% of patients perish?"

"An alternate and effective three-step approach has been used experimentally... First, CPR specifically designed to provide sufficient blood pressure is employed to ensure blood nourishment to the brain. Second, body circulation is supported using a small portable heart-lung machine whose catheters easily access the groin arteries. ...Third, the dead heart is then brought back to life by the delivery of blood containing ...added ingredients ...[T]his new method was applied internationally to 34 sudden death patients. ...80% ...survived ...only one patient sustained brain injury. ...[W]ith present methods... 100% will die if CPR/defibrillation does not return an efficient heartbeat within 15 minutes. Yet these 34 patients underwent CPR for an average of 72 minutes... Because it also treated the cause behind the sudden death and not just the symptom (the heart stopping)."

"A recent survey of 3,292 post-operative patients showed approximately 40% had septums that were bulging or showing "paradoxical motion." ....[A]fter valve surgery [it was] 60%. ...[T]he entire cardiovascular community (cardiologists and surgeons) has a lack in awareness of the critical importance of the septum."

"William Harvey... who in England discovered the circulation... wrote this wonderful book called Anatomical Exercises... [S]uddenly he is here with the new idea of the circulation and some other ideas... He contradicted Vesalius who fitted to the Galenic system of ebb and flow concept. That's the twist and suction that the heart always has. Harvey says it didn't happen that way. It didn't dilate and take the shape of cupping glass and suck blood into it. Well, Harvey was a brilliant and wonderful person, but he wasn't perfect, and he was wrong. Because the heart does exactly what he said it didn't do."

"I picked up a book [The Illustrations from the Works of Andreas Vesalius of Brussels ed., Saunders & O'Malley] on Vesalius... [H]e cut the heart... to see the different cavities... in the 1500s. ...[T]he cardiac structure is the first example since Leonardo da Vinci showing the thickness of the walls and the shape of the cavities."