January 13

As a high-ranking official of the late Goryeo dynasty, he served as a diplomat to China and an advisor at the royal court. Chŏng's poetry, including the famous lament 'I Would Not Serve a Second Master', reflects his commitment to righteousness. He was assassinated in 1392 by agents of Yi Seong-gye, marking the end of the Goryeo dynasty. His steadfast loyalty made him a symbol of integrity in Korean culture, celebrated in literature and folklore. Chŏng Mong-ju's legacy endures as a paragon of ethical governance and scholarly achievement.

Born in 1845 in Bourg-en-Bresse, Félix Tisserand became a professor of astronomy and published influential research on the perturbations of planetary orbits. His comprehensive treatise on celestial mechanics became a standard reference for students and researchers. Tisserand served as director of the Toulouse Observatory and later as a member of the French Academy of Sciences. He also edited key astronomical journals, fostering international collaboration. His eponymous Tisserand criterion remains important in the study of comet and asteroid trajectories. Tisserand's contributions significantly advanced the theoretical foundations of modern astronomy.

Born in 1858 in Kaunas, then part of the Russian Empire, Oskar Minkowski studied medicine and physiology in Germany, where he partnered with Joseph von Mering to demonstrate that removal of the pancreas in dogs induced diabetes. This seminal experiment established the gland's endocrine function and laid the groundwork for future diabetes research. Minkowski held professorships at the University of Freiburg and Berlin, conducting further studies on metabolism and neurological processes. His meticulous approach and groundbreaking findings earned him recognition as a pioneer of endocrinology. Minkowski's work remains a cornerstone of biomedical science, influencing modern treatments for pancreatic disorders.

Born in 1861 in Hamburg, Max Nonne pursued medical studies focusing on neurology, earning acclaim for his precise clinical observations and diagnostic methods. He served as professor of neurology at the Universities of Kiel and Hamburg, where he advanced understanding of muscular dystrophies and brain diseases. Nonne authored seminal textbooks on neurological examination and co-discovered the Nonne-Apelt reaction, a diagnostic sign of meningitis. A founding member and later president of the German Neurological Society, he promoted the professionalization of neurology as a distinct medical field. Nonne's work laid the groundwork for modern neurodiagnostics and patient care.

Born in 1864 in Giessen, Wilhelm Wien made groundbreaking contributions to the study of thermal radiation and electromagnetism. His formulation of Wien's displacement law revealed how the peak wavelength of blackbody radiation shifts with temperature, providing a critical stepping stone toward quantum theory. Wien held professorships in Würzburg and Munich, where he influenced notable students and conducted experiments on gas discharge and cathode rays. He published influential papers that challenged classical physics models and helped inspire Max Planck's quantum hypothesis. In recognition of his achievements, Wien received the Nobel Prize in Physics in 1911. His research continues to underpin modern spectroscopy and astrophysics.

Born in 1870, Harrison studied at Johns Hopkins University before joining the faculty at Yale. In the early 1900s, he developed methods to cultivate animal cells outside the body. His nerve fiber culture experiments laid the foundation for modern cell biology. Harrison's work revolutionized the understanding of embryonic development. He later served as president of the American Association of Anatomists. Throughout his career, he mentored generations of researchers and published influential textbooks.

Born in 1878 in Montreal, Groulx was ordained as a Roman Catholic priest in his twenties. He earned recognition as a historian for his extensive writings on New France and Quebec history. Groulx founded the review L'Action canadienne française to promote French-Canadian nationalism. His scholarly works influenced generations and shaped Quebec's emerging cultural identity. He also taught at the Université de Montréal, where he inspired many students. Groulx's legacy remains central to discussions of Quebec's linguistic and cultural heritage.

Gertrude Mary Cox was born in 1900 in Dayton, Iowa. She earned her Ph.D. in plant breeding and statistics, becoming one of the first female faculty members at North Carolina State University. Cox co-developed influential statistical methods for experimental design that transformed agricultural research. She served as the first female president of the American Statistical Association in 1949. Her work established standards still used in industrial, medical, and social science experiments. Cox's trailblazing career paved the way for generations of women in mathematics and statistics.

A. B. Guthrie Jr. was born in Indiana, Pennsylvania, in 1901 and raised in Montana. He had a prolific career as a historical novelist, dramatizing the American frontier experience. Guthrie's novel 'The Way West' won the Pulitzer Prize for Fiction in 1950. He also worked as a screenwriter, contributing to Hollywood films that depicted Western themes. Later in life, he authored insightful works on Montana history and the Old West. Guthrie's storytelling captured the spirit and struggles of America's frontier era.

Mieczysław Żywczyński was born in Poland in 1901 and ordained a Catholic priest. He devoted his life to historical scholarship, focusing on the medieval and early modern Church. His publications shed light on religious, social, and political aspects of Polish ecclesiastical history. Żywczyński taught at the Jagiellonian University, mentoring new generations of historians. His work remains a valuable resource for understanding Poland's religious heritage. He balanced pastoral duties with rigorous academic research until his death in 1978.

Born in Vienna in 1902, Karl Menger emerged as a central figure in the Vienna Circle. He pioneered dimension theory and introduced the concept of Menger curvature. His work laid foundations for modern topology and functional analysis. Menger taught at universities across Europe and the United States. He authored influential textbooks and papers that continue to shape geometric research. Menger also explored economic theories and game theory applications. He passed away in 1985, leaving a lasting legacy in mathematics.

Zhou Youguang was born in Changzhou, China, in 1906. A trained economist and banker, he shifted to linguistics after 1949. He led the committee that created Hanyu Pinyin, adopted in 1958. Pinyin revolutionized Mandarin teaching and international communication. Zhou continued writing on Chinese phonetics and dialectology into his 100s. He authored essays and memoirs reflecting on language reform and history. Living to 111, he became a symbol of intellectual longevity. Zhou passed away in 2017, leaving a profound impact on language education.