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July 2009 Cyberattacks
The July 2009 cyberattacks were a series of coordinated cyberattacks against major government, news media, and financial websites in South Korea and the United States . The attacks involved the activation of a botnet—a large number of hijacked computers—that maliciously accessed targeted websites with the intention of causing their servers to overload due to the influx of traffic, known as a DDoS attack. Most of the hijacked computers were located in South Korea. The estimated number of the hijacked computers varies widely; around 20,000 according to the South Korean National Intelligence Service, around 50,000 according to Symantec's Security Technology Response group, and more than 166,000 according to a Vietnamese computer security researcher who analyzed the log files of the two servers the attackers controlled. An investigation revealed that at least 39 websites were targets in the attacks based on files stored on compromised systems. The targeting and timing of the attacks—which started the same day as a North Korean short-range ballistic missile test—have led to suggestions that they may be from North Korea, although these suggestions have not been substantiated. Researchers would later find links between these cyberattacks, the DarkSeoul attacks in 2013, and other attacks attributed to the Lazarus Group. This attack is considered by some to be the beginning of a series of DDoS attacks carried about by Lazarus dubbed "Operation Troy."
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Biography
Nick Katz
Nicholas Michael Katz (born December 7, 1943) is an United States mathematician, working in the fields of algebraic geometry, particularly on p-adic methods, monodromy and moduli problems, and number theory. He is currently a professor in the Mathematics Department at Princeton University in Princeton, New Jersey and an editor of the journal Annals of Mathematics.[1] Katz graduated from Johns
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Topic Review
Bi-Directional Text
Bi-directional text is text containing text in both text directionalities, both right-to-left (RTL or dextrosinistral) and left-to-right (LTR or sinistrodextral). It generally involves text containing different types of alphabets, but may also refer to boustrophedon, which is changing text directionality in each row. Some writing systems of the world, including the Arabic and Hebrew scripts or derived systems such as the Persian, Urdu, and Yiddish scripts, are written in a form known as right-to-left (RTL), in which writing begins at the right-hand side of a page and concludes at the left-hand side. This is different from the left-to-right (LTR) direction used by the dominant Latin script. When LTR text is mixed with RTL in the same paragraph, each type of text is written in its own direction, which is known as bi-directional text. This can get rather complex when multiple levels of quotation are used. Many computer programs fail to display bi-directional text correctly. For example, the Hebrew name Sarah (שרה) is spelled: sin (ש) (which appears rightmost), then resh (ר), and finally heh (ה) (which should appear leftmost). Note: Some web browsers may display the Hebrew text in this article in the opposite direction.
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Topic Review
Proofs of Fermat's Theorem on Sums of Two Squares
Fermat's theorem on sums of two squares asserts that an odd prime number p can be expressed as with integer x and y if and only if p is congruent to 1 (mod 4). The statement was announced by Girard in 1625, and again by Fermat in 1640, but neither supplied a proof. The "only if" clause is easy: a perfect square is congruent to 0 or 1 modulo 4, hence a sum of two squares is congruent to 0, 1, or 2. An odd prime number is congruent to either 1 or 3 modulo 4, and the second possibility has just been ruled out. The first proof that such a representation exists was given by Leonhard Euler in 1747 and was complicated. Since then, many different proofs have been found. Among them, the proof using Minkowski's theorem about convex sets and Don Zagier's short proof based on involutions have appeared.
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Topic Review
IEEE 802.11ax-2021
IEEE 802.11ax-2021 or 802.11ax is an IEEE standard for wireless local-area networks (WLANs) and the successor of 802.11ac. It is marketed as Wi-Fi 6 (2.4 GHz and 5 GHz) and Wi-Fi 6E (6 GHz) by the Wi-Fi Alliance. It is also known as High Efficiency Wi-Fi, for the overall improvements to Wi-Fi 6 clients under dense environments. It is designed to operate in license-exempt bands between 1 and 7.125 GHz, including the 2.4 and 5 GHz bands already in common use as well as the much wider 6 GHz band (5.925–7.125 GHz in the US). The main goal of this standard is enhancing throughput-per-area[lower-alpha 1] in high-density scenarios, such as corporate offices, shopping malls and dense residential apartments. While the nominal data rate improvement against 802.11ac is only 37%,:qt the overall throughput improvement (over an entire network) is 400% (hence High Efficiency).:qt This also translates to 75% lower latency. The quadruplication of overall throughput is made possible by a higher spectral efficiency. The key feature underpinning 802.11ax is orthogonal frequency-division multiple access (OFDMA), which is equivalent to cellular technology applied into Wi-Fi.:qt Other improvements on spectrum utilization are better power-control methods to avoid interference with neighboring networks, higher order 1024‑QAM, up-link direction added with the down-link of MIMO and MU-MIMO to further increase throughput, as well as dependability improvements of power consumption and security protocols such as Target Wake Time and WPA3. The IEEE 802.11ax-2021 standard was approved in February 9th, 2021.
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Topic Review
Xbox 360 System Software
The Xbox 360 system software or the Xbox 360 Dashboard is the updateable software and operating system for the Xbox 360. It formerly resided in a 16 MB file system. However, starting with the NXE Update, more storage became a requirement, rectified by either having a Hard Drive installed, or one of the later revisions of the console with adequate flash storage embedded within the console. The system software has access to a maximum of 32 MB of the system's Random Access Memory. The updates can be downloaded from the Xbox Live service directly to the Xbox 360 and subsequently installed. Microsoft has also provided the ability to download system software updates from their respective official Xbox website to their PCs and then storage media, from which the update can be installed to the system. The Xbox 360 game system allows users to download applications that add to the functionality of the dashboard. Most apps required the user to be signed into a valid Xbox Live Gold account in order to use the features advertised for the given app. But as of the 2.0.16756.0 update, most apps do not require an Xbox Live Gold Subscription to access them, although the app may have its own subscription to be able to use it. With the exception of a few early apps, Microsoft has added partners to develop apps for the Xbox 360 system since the New Xbox Experience (NXE) Dashboard update in 2008. Following the success of Xbox One preview program launched in 2014, in March 2015, Microsoft announced the Xbox 360 preview program to the public.
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Topic Review
Encyclopedia of Chicago
The Encyclopedia of Chicago is an historical reference work covering Chicago and the entire Chicago metropolitan area published by the University of Chicago Press. Released in October 2004, the work is the result of a ten-year collaboration between the Newberry Library and the Chicago Historical Society. It exists in both a hardcover print edition and an online format, known as the Electronic Encyclopedia of Chicago. The print edition is 1117 pages and includes 1400 entries, 2000 biographical sketches, 250 significant business enterprise descriptions, and hundreds of maps. Initially, the internet edition included 1766 entries, 1000 more images and sources. The concept was fueled by other regional encyclopedias that had met with commercial success in 1980s and 1990s. Eventually, the vision to create the book found initial financing from the National Endowment for the Humanities. The book was well received and became a bestseller during the 2004 Christmas season following its October 2004 release. The following May the Electronic Encyclopedia of Chicago was released. Northwestern University joined the Newberry Library/Chicago Historical Society collaboration to publish the internet edition. The internet edition was the second of its kind for a U.S. city.
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Topic Review
Examples of Differential Equations
Differential equations arise in many problems in physics, engineering, and other sciences. The following examples show how to solve differential equations in a few simple cases when an exact solution exists.
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Topic Review
Censorship of Twitter
Censorship of Twitter refers to Internet censorship by governments that block access to Twitter. Twitter censorship also includes governmental notice and take down requests to Twitter, which Twitter enforces in accordance with its Terms of Service when a government or authority submits a valid removal request to Twitter indicating that specific content (such as a tweet) is illegal in their jurisdiction.
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Topic Review
ArchiCAD
ARCHICAD is an architectural BIM CAD software for Macintosh and Windows developed by the Hungarian company Graphisoft. ARCHICAD offers computer aided solutions for handling all common aspects of aesthetics and engineering during the whole design process of the built environment — buildings, interiors, urban areas, etc. Development of ARCHICAD started in 1982 for the Apple Lisa, the predecessor of the original Apple Macintosh. Following its launch in 1987, with Graphisoft's "Virtual Building" concept, ARCHICAD became regarded by some as the first implementation of BIM. ARCHICAD has been recognized as the first CAD product on a personal computer able to create both 2D and 3D geometry, as well as the first commercial BIM product for personal computers and considered "revolutionary" for the ability to store large amounts of information within the 3D model. Today, it has over 120,000 users.
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