Jean Piaget was a Swiss psychologist known for his work on child development. Piaget's theory of cognitive development and epistemological view are together called "genetic epistemology". Piaget placed great importance on the education of children; as the Director of the International Bureau of Education, he declared in 1934 that "only education is capable of saving our societies from possible collapse, whether violent, or gradual." His theory of child development is studied in pre-service education programs. Educators continue to incorporate constructivist-based strategies. Piaget created the International Center for Genetic Epistemology in Geneva in 1955 while on the faculty of the University of Geneva and directed the Center until his death in 1980; the number of collaborations that its founding made possible, their impact led to the Center being referred to in the scholarly literature as "Piaget's factory". According to Ernst von Glasersfeld, Jean Piaget was "the great pioneer of the constructivist theory of knowing."

However, his ideas did not become popularized until the 1960s. This led to the emergence of the study of development as a major sub-discipline in psychology. By the end of the 20th century, Piaget was second only to B. F. Skinner as the most cited psychologist of that era. Piaget was born in 1896 in the Francophone region of Switzerland, he was the oldest son of Arthur Piaget, a professor of medieval literature at the University of Neuchâtel, Rebecca Jackson. Piaget was a precocious child who developed an interest in the natural world, his early interest in zoology earned him a reputation among those in the field after he had published several articles on mollusks by the age of 15. When he was 15, his former nanny wrote to his parents to apologize for having once lied to them about fighting off a would-be kidnapper from baby Jean's pram. There never was a kidnapper. Piaget became fascinated that he had somehow formed a memory of this kidnapping incident, a memory that endured after he understood it to be false.

He developed an interest in epistemology due to his godfather's urgings to study the fields of philosophy and logic. He was educated at the University of Neuchâtel, studied at the University of Zürich. During this time, he published two philosophical papers that showed the direction of his thinking at the time, but which he dismissed as adolescent thought, his interest in psychoanalysis, at the time a burgeoning strain of psychology, can be dated to this period. Piaget moved from Switzerland to Paris, France after his graduation and he taught at the Grange-Aux-Belles Street School for Boys; the school was run by the developer of the Binet-Simon test. Piaget assisted in the marking of Binet's intelligence tests, it was while he was helping to mark some of these tests that Piaget noticed that young children gave wrong answers to certain questions. Piaget did not focus so much on the fact of the children's answers being wrong, but that young children made types of mistakes that older children and adults did not.

This led him to the theory that young children's cognitive processes are inherently different from those of adults. He was to propose a global theory of cognitive developmental stages in which individuals exhibit certain common patterns of cognition in each period of development. In 1921, Piaget returned to Switzerland as director of the Rousseau Institute in Geneva. At this time, the institute was directed by Édouard Claparède. Piaget was familiar with many of Claparède's ideas including that of the psychological concept'groping', associated with "trials and errors" observed in human mental patterns. In 1923, he married Valentine Châtenay the couple had three children, whom Piaget studied from infancy. From 1925 to 1929, Piaget worked as a professor of psychology and the philosophy of science at the University of Neuchatel. In 1929, Jean Piaget accepted the post of Director of the International Bureau of Education and remained the head of this international organization until 1968; every year, he drafted his "Director's Speeches" for the IBE Council and for the International Conference on Public Education in which he explicitly addressed his educational credo.

Having taught at the University of Geneva and at the University of Paris, in 1964, Piaget was invited to serve as chief consultant at two conferences at Cornell University and University of California, Berkeley. The conferences addressed the relationship of cognitive studies and curriculum development and strived to conceive implications of recent investigations of children's cognitive development for curricula. In 1979 he was awarded the Balzan Prize for Political Sciences, he died in 1980 and was buried with his family in an unmarked grave in the Cimetière des Rois in Geneva. This was as per his request. Harry Beilin described Jean Piaget's theoretical research program as consisting of four phases: the sociological model of development, the biological model of intellectual development, the elaboration of the logical model of intellectual development, the study of figurative thought; the resulting theoretical frameworks are sufficiently different from each other that they have been characterized as representing different "Piagets."

More Jeremy Burman responded to Beilin and called for the addition of a phase before his turn to psychology: "the zeroeth Piaget." Before Piaget became a psychologist, he trained in natural philosophy. He received a doctorate in 1918 from

Surgical knots are the knots used to bind suture materials together while binding tissue in surgery. They are used in veterinary settings. Surgical knots have been used since the first century when they were described by Greek physician Heraklas in a monograph on surgical knots and slings. In the past, the training of astronauts has included the tying of surgical knots; the effective tying of surgical knots is a critical skill for surgeons since if the knot does not stay intact, the consequences may be serious such as after pulmonary resection, laparoscopic cholecystectomy, hysterectomy. Primary, the goal of surgical knot tying is to allow the capacity of a knot to be tightened and remain tight. Ligatures finished multiple overhand knots. Slipping sometimes happens before the addition of the final knot during an instrument tie; the constrictor knot is the knot most used for binding. The constrictor knot resembles the clove hitch except the two ends form an overhand knot under the overriding turn.

New knots have been described. Other employed knots are surgeon's knot, modified surgeon's knot, single-double other side knot, strangle knot and modified miller’s knot; the Surgeon's knot has been a standard ligature but in one study it demonstrated slippage. While the suture is being put in place a knot is used to secure the suture. Tying the knot may be done inside the body or outside the body. Of these two options knot tying inside the body takes some time to learn because the surgeon is required to use laparoscopic instrumentation rather than his fingers to loop the suture. Tying the knot outside the body is more simple for most surgeons because the suture is looped with fingers as in traditional tying; each knot formed has to be guided through a laparoscopic cannula and made tight with a knot-pusher to create the knot. In laparoscopic surgery, a stronger braided suture is preferred if the knot pusher is used because suture fraying is a side effect of this technique. A disadvantage of knot tying being done outside the body is that it causes more tension and can cause tissue tearing while suturing delicate tissue.

An alternative to the surgical knot is a disposable clip, placed at the end of the suture to keep stitches secure. A hemoclip is a titanium V-shaped clip with extensions that are squeezed together during application; the clips are available in various sizes and were designed to compress vessels for hemostasis. Tying a surgical knot is done inside the body or outside the body. Learning to tie a surgical knot inside the body is more difficult and has a steeper learning curve; this is. Tying the knot outside the body is simpler for most because the suturing is with fingers as in traditional tying; when a surgical knot is formed outside the body it must be drawn into a laparoscopic cannula. Stronger braided suturing thread is preferred because the knot has a tendency to fray as it is slid down the cannula. At the end of the running suture line, clips can be placed across the suture tail. Barbed suture is a knotless surgical suture; these barbs lock the suture into the tissue. Barbed sutures are used in cosmetic and reconstructive surgery.

There are concerns that knot tying may be related to glove puncture but a current study demonstrated that instead friction from continuous suturing only left ‘marks’ on the little finger with no glove puncture. Much effort goes into the training of medical students regarding the surgical skill of knot tying. One method, called “Quiet Eye Training” has shown greater success than more traditional forms of instruction. List of bend knots List of binding knots List of knots List of surgeries by type Surgical Knots, Animated Surgical Knots

The Strategic Arms Limitation Talks were two rounds of bilateral conferences and corresponding international treaties involving the United States and the Soviet Union, the Cold War superpowers, on the issue of arms control. The two rounds of talks and agreements were SALT I and SALT II. Negotiations commenced in Helsinki, Finland, in November 1969. SALT I led to an interim agreement between the two countries. Although SALT II resulted in an agreement in 1979, the United States Senate chose not to ratify the treaty in response to the Soviet war in Afghanistan, which took place that year; the Soviet legislature did not ratify it. The agreement was not renewed; the talks led to the STARTs, or Strategic Arms Reduction Treaties, which consisted of START I and START II, both of which proposed limits on multiple-warhead capacities and other restrictions on each side's number of nuclear weapons. A successor to START I, New START, was proposed and was ratified in February 2011. SALT I is the common name for the Strategic Arms Limitation Talks Agreement signed on May 26, 1972.

SALT I froze the number of strategic ballistic missile launchers at existing levels and provided for the addition of new submarine-launched ballistic missile launchers only after the same number of older intercontinental ballistic missile and SLBM launchers had been dismantled. SALT I limited land-based ICBMs that were in range from the northeastern border of the continental United States to the northwestern border of the continental USSR. In addition to that, SALT I limited the number of SLBM capable submarines that NATO and the United States could operate to 50 with a maximum of 800 SLBM launchers between them. If the United States or NATO were to increase that number, the USSR could respond with increasing their arsenal by the same amount; the strategic nuclear forces of the Soviet Union and the United States were changing in character in 1968. The total number of missiles held by the United States had been static since 1967 at 1,054 ICBMs and 656 SLBMs but there was an increasing number of missiles with multiple independently targetable reentry vehicle warheads being deployed.

MIRVs carried multiple nuclear warheads with dummies, to confuse ABM systems, making MIRV defense by ABM systems difficult and expensive. Both sides were permitted to increase their number of SLBM forces, but only after disassembling an equivalent number of older ICBMs or SLBM launchers on older submarines. One clause of the treaty required both countries to limit the number of deployment sites protected by an anti-ballistic missile system to one each; the idea of this system was that it would prevent a competition in ABM deployment between the US and the Soviet Union. The Soviet Union had deployed such a system around Moscow in 1966 and the United States announced an ABM program to protect twelve ICBM sites in 1967. After 1968, the Soviet Union tested a system for the SS-9 missile, otherwise known as the R-36 missile. A modified two-tier Moscow ABM system is still used; the United States built only one ABM site to protect a Minuteman base in North Dakota where the "Safeguard" Program was deployed.

This base was more vulnerable to attacks by the Soviet ICBMs, because of the advancement in Soviet missile technology. Negotiations lasted from November 17, 1969, until May 1972 in a series of meetings beginning in Helsinki, with the US delegation headed by Gerard C. Smith, director of the Arms Control and Disarmament Agency. Subsequent sessions alternated between Helsinki. After a long deadlock, the first results of SALT I came in May 1971, when an agreement was reached over ABM systems. Further discussion brought the negotiations to an end on May 26, 1972, in Moscow when Richard Nixon and Leonid Brezhnev signed both the Anti-Ballistic Missile Treaty and the Interim Agreement Between The United States of America and The Union of Soviet Socialist Republics on Certain Measures With Respect to the Limitation of Strategic Offensive Arms; the two sides agreed to a number of basic principles regrading appropriate conduct. Each recognized the sovereignty of the other and agreed to the principle of non-interference while at the same seeking to promote economic and cultural ties of mutual benefit and enrichment.

Nixon was proud that thanks to his diplomatic skills, he achieved an agreement that his predecessors were unable to reach. Nixon and Kissinger planned to link arms control to détente and to the resolution of other urgent problems through what Nixon called "linkage." David Tal argues: The linkage between strategic arms limitations and outstanding issues such as the Middle East, Berlin and, Vietnam thus became central to Nixon’s and Kissinger’s policy of détente. Through employment of linkage, they hoped to change the nature and course of U. S. foreign policy, including U. S. nuclear disarmament and arms control policy, to separate them from those practiced by Nixon’s predecessors. They intended, through linkage, to make U. S. arms control policy part of détente.... His policy of linkage had in fact failed, it failed because it was based on flawed assumptions and false premises, the foremost of, that the Soviet Union wanted strategic arms limitation agreement much more than the United States did.

SALT II was a series of talks between United States and Soviet negotiators from 1972 to 1979 which sought to curtail the manufacture of strategic nuclear weapons. It was a continuation of the SALT I was led by representatives from both countries. SALT II