Nemesis is a hypothetical star that was proposed to explain certain periodicities in the extinction events in Earth's geological record. The idea emerged in the 1980s when astronomers suggested that a companion star to our Sun might exist in an eccentric orbit far beyond the Kuiper Belt. This star, if it exists, could potentially disturb the Oort Cloud—a spherical shell of icy objects surrounding the solar system—leading to a higher influx of comets into the inner solar system.

Net Ecosystem Production (NEP) is a key concept in ecology that refers to the balance between the amount of organic matter produced by photosynthetic organisms (like plants and phytoplankton) and the amount of organic matter consumed by respiration processes within an ecosystem. It is essentially a measure of the net carbon dioxide (CO2) uptake by an ecosystem.

Neutron backscattering is a technique used in materials science and condensed matter physics to probe the structure and dynamics of materials at the atomic or molecular level. This technique involves the scattering of neutrons from a sample, where neutrons are directed at the sample and measure how they are deflected or backscattered by the atoms within the material.

Newton's rings are a pattern of concentric circular fringes that appear when a plano-convex lens is placed on a flat glass surface, creating an air film of varying thickness between the two surfaces. This optical phenomenon is named after Sir Isaac Newton, who studied the interference of light. ### Formation: When monochromatic light (light of a single wavelength) is shone on the setup, some of the light reflects off the top surface of the lens while some reflects off the flat glass surface.

The New York Burlesque Festival is an annual event that celebrates the art of burlesque, featuring a variety of performances by both established and emerging burlesque artists. Held in New York City, the festival usually spans several days and includes a series of shows at various venues, workshops, and other events that aim to showcase the diversity and creativity of the burlesque scene.

Nicolaus II Bernoulli (born 1695, died 1726) was a Swiss mathematician and a member of the prominent Bernoulli family, which contributed significantly to the development of mathematics and physics in the 17th and 18th centuries. He is known for his work in probability theory, as well as his contributions to calculus and mathematical physics. One of his notable contributions was in the area of the calculus of variations, where he worked on problems related to optimization.

Noise-induced hearing loss (NIHL) is a type of hearing impairment that occurs as a result of exposure to loud sounds or noise over a prolonged period or due to a single, intense noise event, such as an explosion. It is one of the most common types of hearing loss and can affect people of all ages.

The Noncommutative Standard Model (NCSM) is an approach in theoretical physics that seeks to reconcile the principles of quantum mechanics with the requirements of a gauge theory that describes the fundamental interactions in particle physics. It is an extension of the conventional Standard Model of particle physics, which describes electromagnetic, weak, and strong interactions using quantum field theory.

A nonlinear X-wave is a specific type of wave solution that arises in the context of nonlinear partial differential equations, particularly in wave propagation phenomena. This wave can be characterized by its distinct features: it often involves a localized wave packet that maintains its shape as it propagates through a medium, despite the effects of nonlinearity.

Non-numerical words for quantities are terms that describe amounts or degrees without using specific numbers. These words can indicate various levels of quantity, frequency, or intensity. Here are some examples: 1. **Some** - Indicating an unspecified amount, usually more than a few. 2. **Many** - A large number, though not specified. 3. **Few** - A small number, generally less than expected.

Nonsingular black hole models are theoretical constructs in the field of general relativity and theoretical physics that attempt to describe black holes without the singularities that traditional models, such as the Schwarzschild or Kerr black holes, predict. In standard general relativity, singularities are points in spacetime where the gravitational field becomes infinite, and physical quantities cease to be well-defined. This situation arises at the center of a black hole, leading to what is known as a gravitational singularity.

The Nordic Mathematical Contest (NMC) is a mathematical competition designed for high school students from Nordic countries, which typically include Denmark, Finland, Iceland, Norway, and Sweden. The contest aims to encourage mathematical thinking and problem-solving skills among students. The competition usually consists of several individual problems, which participants must solve within a limited time frame. Problems can cover a wide range of mathematical topics, including algebra, geometry, number theory, and combinatorics.

In the context of mathematics, particularly in topology and differential geometry, a **normal surface** typically refers to a type of surface that is embedded in a three-dimensional space and satisfies certain conditions regarding its curvature and other geometric properties. However, the term "normal surface" may also have specific meanings in different subfields of mathematics, such as in the study of 3-manifolds or algebraic geometry.

Norman Christ is a prominent American theoretical physicist known for his contributions to various areas of particle physics and quantum field theory. He has worked on lattice gauge theory, which is a method used to study quantum field theories, particularly quantum chromodynamics (QCD), using a discretized version of spacetime. Christ has held academic positions at institutions such as Columbia University and has been involved in research that bridges theoretical ideas with computational techniques.

The Northeastern Statistical Region typically refers to a designated area used for statistical analysis and reporting purposes. Such regions often encompass multiple municipalities or counties to facilitate regional planning, economic development, and demographic studies. In different countries, the term may refer to specific administrative divisions. For example, in Bulgaria, the Northeastern Statistical Region includes several provinces such as Varna and Dobrich.

The Nor'west Arch is a meteorological phenomenon that occurs primarily in New Zealand, particularly in the South Island. It refers to a specific type of weather pattern characterized by a distinctive arching of the moist air that travels from the Tasman Sea over the Southern Alps. As the warm, moist air approaches the Alps, it is forced upwards, which can lead to heavy rainfall on the windward side of the mountains.

The Novaya Zemlya effect refers to a meteorological phenomenon that occurs in the Arctic regions, particularly associated with the Novaya Zemlya archipelago in Russia. It involves an optical illusion caused by the unique atmospheric conditions of the area, such as temperature inversions and the presence of cold air over warmer waters or land. This effect can result in the appearance of objects (like land or ships) being displaced from their actual positions.

N-rays are a purported type of radiation that was reported in the early 20th century by French physicist Blondlot. N-rays were said to be emitted by certain materials, particularly those that were subjected to certain conditions, like exposure to light. Blondlot claimed that these rays could be detected using a very sensitive apparatus, but their existence was met with skepticism. The concept of N-rays gained some notoriety after Blondlot's experiments were published in scientific journals.

Nuclear materials refer to substances that can be used in the production of nuclear energy or nuclear weapons. These materials are primarily associated with nuclear reactors, nuclear fuel cycles, and various applications in research, medicine, and industry. There are several categories of nuclear materials, primarily including: 1. **Fissile Materials**: These materials can sustain a nuclear chain reaction.

Nuclear power has been utilized by various countries since the mid-20th century, and its development has varied widely across nations due to factors like political decisions, economic considerations, and public opinion. Here's an overview of several key countries that have utilized or are currently utilizing nuclear power: ### 1. **United States** - The U.S. was the first country to develop nuclear power for commercial use, with the first commercial reactor coming online in 1958.