Yanosuke Otsuka () (11 July 1903 – 7 August 1950) was a Japanese

geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althou ...

and professor. Yanosuke Otsuka was born in

Nihonbashi is a business district of Chūō, Tokyo, Japan which grew up around the bridge of the same name which has linked two sides of the Nihonbashi River at this site since the 17th century. The first wooden bridge was completed in 1603. The current ...

Tokyo Tokyo (; ja, 東京, , ), officially the Tokyo Metropolis ( ja, 東京都, label=none, ), is the capital and largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, with an estimated 37.468 ...

on 11 July 1903. He went to the Junior High School attached to Tokyo Higher Normal School (), and after that to Shizuoka High School (). For his undergraduate studies, he entered the Department of Geology, Faculty of Science,

Imperial University of Tokyo , abbreviated as or UTokyo, is a public research university located in Bunkyō, Tokyo, Japan. Established in 1877, the university was the first Imperial University and is currently a Top Type university of the Top Global University Project by ...

, where he graduated in 1929. While he was student, he learned the methods of historical geology from Yoshiaki Ozawa,

topography Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary sci ...

from Taro Tsujimura (), and Cenozoic biological

stratigraphy Stratigraphy is a branch of geology concerned with the study of rock (geology), rock layers (Stratum, strata) and layering (stratification). It is primarily used in the study of sedimentary rock, sedimentary and layered volcanic rocks. Stratigrap ...

from Shigeyasu Tokunaga. After graduation, he entered the Earthquake Research Institute as an assistant in 1930, becoming an associate professor in 1939 and a professor in 1943. He made significant contributions in characterizing the surface faults in the circum-Pacific area, effects of

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explo ...

tectonics Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents k ...

of crustal movements,

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

of molluscs,

paleoclimatology Paleoclimatology (British spelling, palaeoclimatology) is the study of climates for which direct measurements were not taken. As instrumental records only span a tiny part of Earth's history, the reconstruction of ancient climate is important to ...

, mapping of

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...

strata, and the

Tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...

history of the Japanese islands. He died prematurely from

pulmonary tuberculosis Tuberculosis (TB) is an infectious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in w ...

on 7 August 1950, at the age of 47, because effective

antimicrobial therapy An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ar ...

was not yet available in Japan at the time. In biology, he is known for the Otsuka similarity coefficient (also known as Otsuka-Ochiai or Ochiai coefficient), which can be represented as: :

K =\frac

Here,

A

and

B

are sets, and

, A,

is the number of elements in

A

. If sets are represented as

bit vector A bit array (also known as bitmask, bit map, bit set, bit string, or bit vector) is an array data structure that compactly stores bits. It can be used to implement a simple set data structure. A bit array is effective at exploiting bit-level pa ...

s, the Otsuka similarity coefficient can be seen to be the same as the cosine similarity. In a recent book, the Otsuka similarity coefficient is misattributed to another Japanese researcher with the family name Otsuka. The confusion arises because in 1957 Akira Ochiai attributes the coefficient only to Otsuka (no first name mentioned) by citing an article by Ikuso Hamai ( ja, 浜井生三), who in turn cites the original 1936 article by Yanosuke Otsuka.

References

{{authority control Japanese geologists 1903 births 1950 deaths Academics from Tokyo People from Chūō, Tokyo 20th-century geologists 20th-century deaths from tuberculosis Tuberculosis deaths in Japan