Fisher's Principle of gender ratio

Ronald Fisher in his 1930 book "The genetical theory of natural selection" explains why the male to female ratio in most species is 1:1. It is one of the most celebrated principles in evolutionary biology. It may be wrongly attributed to him and scientists before him may knew it. He popularized it with his book and attracted the attention of wider community. 

If a community or group of animals has a tendency to produce offspring of one sex, natural selection prefers the representative parents who have that tendency in the community when the population of that sex is less compared to that of other sex or it prefers different kind of parents otherwise. Once the ratio is achieved, it can swing to other side again and the process repeats.

Fisher is a British scientist and biologist. Works of him along with British geneticist JBS Haldene and American geneticist Sewell Wright is considered to be founded the discipline of population genetics. He did several other contributions to biology like fisherian runway that explains why male peacocks and other animals have natural decorations.

References
Population Genetics
Fisher's principle
Ronald Fisher

Mount Rushmore

Mount Rushmore is a national memorial located in blackhills in Keystone, South Dakota, US. It has pictures of four presidents, George Washington, Thomas Jefferson, Theodore Roosevelt and Abraham Lincoln, sculpted into a granite rock hill. 

It was done by danish american Gutzon Borglum and his son, Lincoln Borglum. The carving starred in 1927 and completed in 1941. It was done with the support from president Calvin Cooledge and senator Peter Norbeck. 

See Mount Rushmore wikipedia link

Great circle distance

Earth is sphere and more accurately a spheroid. Calculating distance between two points on earth is different to calculating the distance between the two points on flat surface. The Circle that connects the two points with center of the sphere as the center is called great circle. The distance between the points is the length of the arc between the points on great circle.

Approximate method:
Circumference of earth at equator is 40,076km and we have 360 degrees in circle and so each degree of longitude at equator is about to 111.32km or 69 miles. The distance between two longitude lines decrease from the equator to poles.

Around 30 degrees north or south from the equator, one degree of longitude is about 96.41km. Around 45 degrees north or south of equator, one degree of longitude is 78.71km. Around 60 degrees, one degree of longitude is 55.66km. Around 75 degrees north or south of equator, one degree of longitude is 28.82km. Around 90 degrees from the equator, that will be poles and one degree of longitude is zero distance.  

However the distance between two lines of latitude stay almost same anywhere from equator to poles. Small difference is because of the shape of the earth. One degree of latitude is 110.57km at equator and 111.69km at poles.

Once we have longitudinal distance and latitude distance between two points, we can compute the distance between two points. The Pythagoras theorem can be used here.

Using cosine law:
Suppose the geographical latitude and longitude of two points on the earth are a1, a2 and b1. We can compute the central angle between them is given by the spherical law of cosines
c = arccos(sin(a1).sin(a2) + cos(a1).cos(a2).cos(|b2-b1|))
The distance d, or the arc length on a sphere of radius r formed by spherical angle c in radians  = r. c; 

Using haversine law:
Alternatively if we know the linear distance between the points as w and using sine law, length of arc on great circle can be calculated as 2*r*arcsin(w/(2.r)).

References
Lat Lang Story
Great circle distance using cosine law
Great circle distance using sine law
Longititude and latitude measuring

California King

Twin or single - 39 inches x 75 inches = 99 cm x 191 cm = 3' 3'' x 6' 3''
Twin XL - 39 inches x 80 inches = 99 cm x 203 cm = 3' 3'' x 6' 8''
Three quarters - 48 inches x 75 inches = 122 cm x 191 cm = 4' x 6' 3''
Full or Double - 54 inches x 75 inches  = 137 cm x 191 cm = 4' 6'' x 6' 3''

US Queen or UK king - 60 inches x 80 inches = 152 cm x 203 cm = 5' x 6' 8''
US King or UK Superking - two twin xl - 76 inches x 80 inches = 193 cm x 203 cm = 6' 4'' x 6' 8''
Cal King - 72 inches x 84 inches = 183 cm x 213 cm = 6 foot x 7 foot

References;
* Mattress dimensions
* Bed size
* Bed sizes

Ethernet MTU limits TCP MSS

TCP Maximum segment size (MSS) or payload in TCP packet is typically 1460 bytes only!

Length of IP packet is capped by 16 bytes field in IP header which itself is 20 bytes and so MTU for protocols on top of IP is = 2^16 - 20 = 65515 bytes and it is much larger than 1460 bytes.

TCP implementations want to use lowest mss that can avoid the packet fragmentation over the internet.

Maximum transfer unit (MTU) is the size of the largest payload a packet can contain after subtracting the header and other metadata information needed to transmit the payload.

Ethernet frame size is 1530 bytes, but ethernet MTU is only 1500 bytes. Payload is preceded by ethernet header and is followed by Frame check Sequence(FCS).
* preamble 7 bytes, start frame 1 byte
* header 14 to 18 bytes - source addr, dst addr, optional 802.1 vlan tag and payload type.
* FCS - 4 bytes.

Subtracting 20 bytes for IP header and 20 bytes for TCP header, 1500 - 40 = 1460 bytes.

References
* Ethernet frame

Loksatta anniversary

Lok Satta Party Invitation for 5th Anniversary Hello,   We are glad to let you know that Lok Satta Party will be celebrating its  Fifth Anniversary at Ongole, Prakasam district headquarters, Andhra Pradesh on October 8th and 9th . We cordially invite you to attend this event and make it a huge success. The program begins with a conference of State party leaders with party President Dr. Jayaprakash Narayan in the chair on October 8. There will be a public meeting on the same day starting at 5 PM in DRRM High School grounds. The State Working Committee will meet on October 9.      The agenda of the two day meetings would be to discuss and finalize an action plan to achieve electoral and administrative reforms as a follow up to the institution of powerful and independent anti corruption mechanisms in the country. It would also focus on measures to empower citizens through devolution of powers and resources on local bodies. It would draw up plans to launch an agitation for conduct of timely local body elections and to strengthen the party organization.    For local support on this event, please call the Indian numbers: 08592 225299 / 9705444604   We request your generous monitory support as it is a critical meeting involving hosting thousands of supporters at one place. You can donate at  www.loksatta.org/cms/index.php?option=com_loksattadonations   In the comments section, please write – “For Ongole Plenary Meetings”. Send confirmation number to Mr. Pavan Kalvagunta (pavankalavagunta@gmail.com). He is working in Constituency Promotion Project, Ongole and is taking care of fund management besides other project related activities.     Warm Regards, LSP Membership Team +91 40 66736672 Lok Satta Party             www.PeopleForLoksatta.org  | PO Box 1701 Newark, CA 9456 United States People For Lok Satta

Loksatta call

E-board call to PFL members and supporters