The Distributed Checksum Clearinghouse (DCC) is a system designed to help detect and prevent unsolicited bulk email (spam) by using checksums to identify and verify the content of messages. It is a collaborative filtering system that allows email servers to efficiently share information about known spam messages.
A disc permeameter is a laboratory device used to measure the permeability of granular soils, sediments, or porous materials. It is specifically designed to assess how easily fluids, such as water, can flow through a given sample of material. ### Key Features of a Disc Permeameter: 1. **Design**: It typically consists of a circular or disc-shaped sample holder with a permeable base that allows fluid to pass through the soil sample.
Jupiter's South Pole refers to the southernmost region of the planet Jupiter, the largest planet in our solar system. This area has garnered significant interest from scientists, particularly due to its unique atmospheric dynamics and features. The South Pole of Jupiter is characterized by a series of cyclones and a jet stream that creates complex weather patterns. One of the most notable features detected in this region is a cluster of persistent cyclones arranged in a polygonal pattern around a central storm.
Infiltration in hydrology refers to the process through which water on the ground surface enters the soil. This process is a critical component of the hydrological cycle and significantly influences soil moisture, groundwater recharge, and overall water availability in an ecosystem. Several factors affect the rate of infiltration, including: 1. **Soil Type**: Different soil textures (sand, silt, clay) have varying capacities for infiltration.
Richards equation is a fundamental partial differential equation that describes the movement of water in unsaturated soils. It is particularly important in hydrogeology, soil physics, and civil engineering, as it models how water infiltrates into and moves through soil layers under the influence of gravity and capillary forces.
The Runoff Curve Number (CN) is a key concept in hydrology used to estimate direct runoff from rainfall events. It is part of the Soil Conservation Service (SCS) method, developed by the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS). ### Key Points About Runoff Curve Number: 1. **Definition**: The CN represents the potential for runoff from a rainfall event based on land use, soil type, and hydrological conditions.
A soil moisture sensor is a device used to measure the moisture level in the soil. These sensors are vital tools for agriculture, horticulture, and gardening, helping to optimize water usage and improve plant health. By providing real-time data about soil moisture conditions, they allow farmers and gardeners to make informed irrigation decisions. ### Types of Soil Moisture Sensors: 1. **Capacitive Sensors**: These sensors measure soil moisture by detecting changes in the soil's dielectric constant, which varies with water content.
The Kirkhill Astronomical Pillar, also known as the Kirkhill Observatory or Kirkhill Pillar, is an astronomical structure located near Kirkhill in Scotland. It was built in the early 19th century, around 1824, by the Reverend Robert A. Smith, who was a notable astronomer of his time. The pillar served as a sundial and was designed to assist in astronomical observations and provide a means to measure time using the sun's position.
The Anti-Spam Research Group (ASRG) is an organization focused on the study and dissemination of research related to spam and anti-spam technologies. It is typically made up of researchers, industry experts, and individuals interested in combating spam, which is the unsolicited and often unwanted electronic communication that clutters email inboxes and other messaging systems. The group works to address the challenges posed by spam through collaboration, sharing findings, and providing solutions that can help improve filtering techniques and overall email security.
"Brazilians physicists" generally refers to physicists from Brazil or those who are associated with Brazilian institutions and contributions to the field of physics. Brazil has a rich history in the physical sciences and has produced many notable physicists, who have made significant contributions in various areas such as condensed matter physics, astrophysics, particle physics, and more.
"Borders" can refer to different concepts depending on the context: 1. **Geographical Borders**: Borders are the defined lines that separate different political or geographical areas, such as countries, states, or regions. They can be natural (like rivers or mountains) or man-made (like fences or walls) and often have regulatory implications for trade, travel, and governance.
Virut is a type of computer virus that primarily affects Windows operating systems. It is classified as a polymorphic file infector, meaning it can change its code to evade detection by antivirus software. Virut infects executable files and spreads through various means, such as file sharing, removable drives, and malicious downloads. Once infected, Virut can cause various issues, including degrading system performance, creating backdoors for attackers, and potentially spreading to other files and systems.
"The Lowe Files" is a reality television series that premiered in August 2017. The show stars actor Rob Lowe and his two sons, Matthew and John Owen Lowe, as they embark on adventures exploring various myths, legends, and paranormal phenomena across the United States. The series follows them as they investigate topics like Bigfoot, UFOs, and other mysteries, often incorporating elements of humor and personal anecdotes.
Cooling flow refers to a process in astrophysics and cosmology where hot gas loses energy and cools down over time, often resulting in a flow of gas towards a central gravitational source, such as a galaxy or galaxy cluster. This phenomenon is particularly relevant in the context of the intracluster medium (ICM) in galaxy clusters, where the hot, X-ray emitting gas can experience cooling below a certain temperature threshold.
In plasma physics, a double layer refers to a structure formed in a plasma (an ionized gas consisting of charged particles) where there exists a significant potential difference across a relatively thin region. This potential difference can separate regions of differing densities of electrons and ions, leading to the creation of a layer that can efficiently accelerate charged particles. Double layers occur in various plasma environments, such as in space plasmas (e.g., in the solar wind) or laboratory plasma experiments.
Web scraping is the automated process of extracting data from websites. It involves fetching the web pages of a website and then parsing the content to retrieve specific information. This process can be used for a variety of purposes, such as data analysis, research, market intelligence, price monitoring, and more.
The 2021 FBI email hack refers to a cybersecurity incident that occurred in November 2021, involving the compromise of an FBI email system used for sending alerts and notifications. Hackers exploited a vulnerability in the system to send out a large number of bogus emails, warning recipients of a supposed cybercrime linked to a fictitious ongoing attack. The emails, which appeared to come from the FBI's "june@ic.fbi.
The Anti-Phishing Working Group (APWG) is an international organization that focuses on combating phishing and other forms of online fraud. Established in 2003, the APWG brings together various stakeholders, including technology companies, law enforcement agencies, financial institutions, and academic researchers, to collaborate on countering phishing attacks and associated online threats.
Bagle is a family of computer worms that emerged in the early 2000s, primarily known for its ability to spread through email attachments and its use of social engineering tactics to trick users into executing the malicious code. The first variant, Bagle.A, was discovered in January 2004. Key characteristics of Bagle include: 1. **Propagation**: Bagle spreads via emails with infected attachments, often disguised as important documents or software.
The CAN-SPAM Act of 2003, which stands for "Controlling the Assault of Non-Solicited Pornography And Marketing Act," is a U.S. federal law that sets the rules for commercial email communications. The primary goal of the Act is to reduce unsolicited and misleading emails, commonly known as spam, and to protect consumers' rights to control the volume and nature of email they receive.

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 2.
    You can publish local OurBigBook lightweight markup files to either https://OurBigBook.com or as a static website
    .
    Figure 3.
    Visual Studio Code extension installation
    .
    Figure 4.
    Visual Studio Code extension tree navigation
    .
    Figure 5.
    Web editor
    . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
    Video 4.
    OurBigBook Visual Studio Code extension editing and navigation demo
    . Source.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact