Hadwiger's theorem is a fundamental result in graph theory, which relates to the colorability of graphs.

Hamiltonian fluid mechanics is a framework for studying fluid dynamics using the principles of Hamiltonian mechanics, which is a reformulation of classical mechanics. In this approach, fluids are treated analogous to particles in a Hamiltonian system, and the governing equations of fluid motion are derived from a Hamiltonian function, which encapsulates the total energy of the fluid system.

Hancock Seamount is an underwater volcanic feature located in the Pacific Ocean, specifically part of the Hawaiian-Emperor seamount chain. It is situated to the northwest of the Hawaiian Islands and is largely submerged beneath the ocean surface. Seamounts like Hancock are formed from volcanic activity, typically associated with hotspots in the Earth's mantle, and can be significant for marine ecosystems, serving as habitats for various marine life.

Hans Munthe-Kaas is a Norwegian mathematician known for his work in the fields of algebra, topology, and representation theory. He is particularly noted for his contributions to the theory of operads and homotopy theory, as well as his involvement in various mathematical research topics related to these areas.

The Hans Oeschger Medal is an award given by the European Geosciences Union (EGU) to recognize outstanding achievements in the field of climate research. Established to honor the contributions of Swiss scientist Hans Oeschger, who was a pioneer in the study of climate change and paleoclimatology, the medal is awarded to scientists who have made significant contributions to understanding the climate system and its variability over time.

Harald Wergeland is a cultural figure in Norway, primarily known as a poet, playwright, and literary scholar. His contributions to Norwegian literature and theater are significant, as he is considered an important part of the country's literary heritage. Wergeland's work often reflects themes of nationalism, social issues, and the human experience, making him a key figure in 19th-century Norwegian literature.

A health indicator is a measurable characteristic or variable that provides insights into the health status of individuals, populations, or communities. Health indicators can be used to assess health outcomes, risks, and behaviors, as well as the effectiveness of health interventions and policies. They serve as vital tools for public health monitoring, research, and decision-making.

Heavy ion fusion is a type of nuclear fusion that involves the use of heavy ions—atomic nuclei that are relatively large and carry a positive charge—to induce fusion reactions in other nuclei. This approach is often studied in the context of achieving controlled nuclear fusion for energy production or for basic research in nuclear physics.

A heavy snow warning is a weather alert issued by meteorological agencies to indicate that significant snowfall is expected over a specific area within a certain timeframe. This warning typically means that accumulations of a certain amount of snow (often defined by local criteria) are anticipated, which could lead to hazardous conditions such as difficult travel, reduced visibility, and potential impacts on infrastructure and services. The criteria for what constitutes a heavy snow warning can vary by region due to differences in climate and typical weather patterns.

Here are the heights of several U.S. Presidents and notable presidential candidates: 1. **George Washington**: 6'2" 2. **Thomas Jefferson**: 6'2" 3. **Abraham Lincoln**: 6'4" 4. **Theodore Roosevelt**: 5'10" 5. **William Howard Taft**: 5'11" 6. **Franklin D. Roosevelt**: 6'2" 7. **John F.

Heinrich Wilhelm Brandes (1890–1979) was a German chemist known for his contributions to various fields of chemistry during the 20th century. He made significant advancements in the study of synthetic substances, particularly in the context of polymer chemistry. Brandes's research focused on the development and application of new materials, which had implications in multiple industries, including plastics and manufacturing.

A Helium-Neon (He-Ne) laser is a type of gas laser that utilizes a mixture of helium and neon gases to produce coherent light. It was one of the earliest types of lasers developed and is widely used in various applications due to its relatively simple design and stability. ### Key Characteristics: 1. **Working Principle**: The laser operates on the principle of stimulated emission. In a helium-neon laser, an electrical discharge excites helium atoms in the gas mixture.

Heljan is a manufacturer of model trains and related products, headquartered in Denmark. Founded in 1958, the company specializes in model railway items, particularly in the scales of HO (1:87) and O (1:43.5) gauge. Heljan is known for producing high-quality models of locomotives, rolling stock, and various accessories, often focusing on prototypes from British, Danish, and other European railways.

"Hellraisers Ball: Caught in the Act" is a film that blends elements of the horror and comedy genres. It features a storyline centered around a group of partygoers at a wild event called the Hellraisers Ball. The film typically incorporates campy humor, supernatural elements, and over-the-top scenarios, showcasing characters that navigate the chaos and terror of the night.

Henry Roy Brahana, commonly known as H.R. Brahana, was an American geologist notable for his contributions to the field of geology, particularly in the study of sedimentology and stratigraphy. He is best known for his work related to sedimentary processes and the interpretation of sedimentary rocks. His research has been influential in understanding geological formations and the history of the Earth.

Hideo Ohno is a prominent Japanese physicist known for his work in the field of semiconductor physics and spintronics. He has made significant contributions to the understanding of magnetic semiconductors and their applications in spintronic devices, which leverage both the charge and spin of electrons for improved functionality in electronics. His research may involve developing new materials and exploring the fundamental properties of these systems for future technological advancements.

The Herchel Smith Professor of Pure Mathematics is a prestigious academic position associated with the University of Cambridge. This chair is named after Herchel Smith, a notable benefactor and philanthropist who made significant contributions to the field of mathematics and education. The position is typically held by a distinguished mathematician who specializes in pure mathematics, which encompasses areas such as algebra, analysis, geometry, and topology, among others.

A Hermitian symmetric space is a type of Riemannian manifold that possesses a certain symmetric structure along with a compatible complex structure. More specifically, a Hermitian symmetric space is defined as a homogeneous space \( G/K \) where: 1. **Complex Structure**: The space has a complex manifold structure, meaning it can be described using complex coordinates, and it possesses a compatible Hermitian metric \( g \).

A Hessenberg matrix is a special kind of square matrix that has zero entries below the first subdiagonal.

Higher spin alternating sign matrices (ASMs) are a generalization of the classical alternating sign matrices, which are combinatorial objects studied in combinatorics and statistical mechanics.