Merit Ptah (“Beloved of the god Ptah”; c. 2700 BCE) was an early physician in ancient Egypt. She is most notable for being the first woman known by name in the history of the field of medicine. Her picture can be seen on a tomb in the necropolis near the step pyramid of Saqqara. Her son, who was a High Priest, described her as “the Chief Physician.”
The physician Merit Ptah should not be confused with Merit-Ptah, the wife of Ramose, the Governor of Thebes and Vizier under Akhenaten, who is depicted with her husband in TT55 in Sheikh Abd el-Qurna.
The International Astronomical Union named the impact crater Merit Ptah on Venus after her
From The Ancient Kemetic Roots of Library and Information Science
By Itibari M. Zulu
A Library: A Literature
An obvious axiom in any discussion of libraries is that one must first have a literature in order to have a library. In this regard, Kemet was rich: (1) the Egyptian language is the oldest written (via hieroglyphics) language in existence (McWhirter, 1982, 166); (2) evidence of a literature is present in the library of Akhenaton (Amenhotep/Amenophis, IV) which contains numerous clay tablets/books in cuneiform writing representing diplomatic correspondence between Amenhotep III, Akhenaton’s father, and nation‑states subject to Egypt (Metzger, 1980, 211); (3) the Palermo Stone, a book of annals of Kemet mentioning Seshait (Seshat/Sesheta) as the goddess of libraries, writing, and letters (Richardson, 1914, 58‑60); and (4) the text of the Precepts of Ptah‑hotep, one of the first (c. 4000 B.C.) philosophical compositions (composed 2,000 years before the Ten Commandments of Moses and 2,500 years before the Proverbs of Solomon), engraved in stone (Nichols, 1964, 33‑34).
Hence literature in ancient Kemet was common and varied in its form. Sometimes it was on papyrus and at other times it was carved/engraved in stone (c. 2700 B.C.) on the walls of temples (library‑universities), pyramids, and other monuments (Nichols, 1964, 32). Fortunately, works written in stone have survived, to provide unequivocal evidence of an extensive Kemetic tradition.7 Continue reading
Top 20 Arithmetic Progression of Primes
by Chris Caldwell
The Prime Pages keeps a list of the 5000 largest known primes, plus a few each of certain selected archivable forms and classes. These forms are defined in this collection’s home page. This page is about one of those forms.
Definitions and Notes
Are there infinitely many primes in most arithmetic progressions? Certainly not if the common difference has a prime factor in common with one of the terms (for example: 6, 9, 12, 15, …). In 1837, Dirichlet proved that in all other cases the answer was yes:
- Dirichlet’s Theorem on Primes in Arithmetic Progressions
- If a and b are relatively prime positive integers, then the arithmetic progression a, a+b, a+2b, a+3b, … contains infinitely many primes.
Prime Arithmetic Progression
An arithmetic progression of primes is a set of primes of the form for fixed and and consecutive , i.e., . For example, 199, 409, 619, 829, 1039, 1249, 1459, 1669, 1879, 2089 is a 10-term arithmetic progression of primes with difference 210.
It had long been conjectured that there exist arbitrarily long sequences of primes in arithmetic progression (Guy 1994). As early as 1770, Lagrange and Waring investigated how large the common difference of an arithmetic progression of primes must be. In 1923, Hardy and Littlewood (1923) made a very general conjecture known as the k-tuple conjecture about the distribution of prime constellations, which includes the hypothesis that there exist infinitely long prime arithmetic progressions as a special case. Important additional theoretical progress was subsequently made by van der Corput (1939), who proved than there are infinitely many triples of primes in arithmetic progression, and Heath-Brown (1981), who proved that there are infinitely many four-term progressions consisting of three primes and a number that is either a prime or semiprime. Continue reading
Waves – Lesson 1 – The Nature of a Wave
From Physics Classroom
Categories of Waves
Waves come in many shapes and forms. While all waves share some basic characteristic properties and behaviors, some waves can be distinguished from others based on some observable (and some non-observable) characteristics. It is common to categorize waves based on these distinguishing characteristics.
Longitudinal versus Transverse Waves versus Surface Waves
One way to categorize waves is on the basis of the direction of movement of the individual particles of the medium relative to the direction that the waves travel. Categorizing waves on this basis leads to three notable categories: transverse waves, longitudinal waves, and surface waves. Continue reading
Does Military Sonar Kill Marine Wildlife?
From Scientific American, June 10, 2009
Dear EarthTalk: Is it true that military sonar exercises actually kill marine wildlife? — John Slocum, Newport, RI
Unfortunately for many whales, dolphins and other marine life, the use of underwater sonar (short for sound navigation and ranging) can lead to injury and even death. Sonar systems—first developed by the U.S. Navy to detect enemy submarines—generate slow-rolling sound waves topping out at around 235 decibels; the world’s loudest rock bands top out at only 130. These sound waves can travel for hundreds of miles under water, and can retain an intensity of 140 decibels as far as 300 miles from their source.
These rolling walls of noise are no doubt too much for some marine wildlife. While little is known about any direct physiological effects of sonar waves on marine species, evidence shows that whales will swim hundreds of miles, rapidly change their depth (sometime leading to bleeding from the eyes and ears), and even beach themselves to get away from the sounds of sonar. Continue reading
How does sonar work?
From Science Wire
Sonar is simply making use of an echo. When an animal or machine makes a noise, it sends sound waves into the environment around it. Those waves bounce off nearby objects, and some of them reflect back to the object that made the noise. It’s those reflected sound waves that you hear when your voice echoes back to you from a canyon. Whales and specialized machines can use reflected waves to locate distant objects and sense their shape and movement.
The range of low-frequency sonar is remarkable. Dolphins and whales can tell the difference between objects as small as a BB pellet from 50 feet (15 meters) away, and they use sonar much more than sight to find their food, families, and direction. Continue reading