PB
Paul Biya (born Paul Barthélemy Biya'a bi Mvondo; 13 February 1933) is a Cameroonian politician who has served as the second president of Cameroon since 6 November 1982.[1] Born in the village of Mvomeka'a in southern Cameroon, he rose through administrative ranks under President Ahmadou Ahidjo, serving as prime minister from 1975 until assuming the presidency following Ahidjo's resignation.[1][2] Biya, who heads the Cameroon People's Democratic Union (RDPC), is Africa's second-longest-serving head of state after Teodoro Obiang of Equatorial Guinea, with his tenure marked by constitutional changes extending term limits and multiple reelections, including victories in 1988, 1992, 1997, 2004, 2011, and 2018.[3][4] Under Biya's leadership, Cameroon has maintained relative political stability amid regional challenges, including the prevention of widespread civil war post-independence and economic diversification through oil revenues and agricultural exports, though growth has been uneven and dependent on commodity prices.[2] His administration has prioritized infrastructure development, such as dams and highways, and hosted international events like the 2019 Africa Cup of Nations, bolstering national cohesion in a bilingual federation.[4] However, his rule has faced domestic and international scrutiny over governance issues, including the 2016-ongoing Anglophone separatist crisis, which has displaced hundreds of thousands and resulted in thousands of deaths, as well as allegations of electoral fraud and suppression of opposition, often amplified by Western outlets despite evidence of voter turnout and RDPC organizational strength.[3][5] Biya's longevity in power reflects effective patronage networks and party dominance, though at 92 years old in 2025, questions persist about succession amid his limited public appearances.[1][6]Science and chemistry
Chemical elements and compounds
Lead (Pb) is the chemical symbol for the element lead, a post-transition metal with atomic number 82 and standard atomic weight of 207.2(1) u.[7] Derived from the Latin plumbum, the symbol reflects historical naming conventions rather than the English term.[8] Lead occurs as a dense, soft, bluish-gray solid at room temperature, with a density of 11.34 g/cm³, making it one of the denser common metals.[9] It has a low melting point of 327.46 °C and is highly malleable and ductile, though a poor conductor of electricity.[10] Upon exposure to air, lead rapidly tarnishes to form a dull oxide layer.[8] Lead exhibits oxidation states of +2 and +4, forming compounds such as lead(II) oxide (PbO), a yellow powder used historically in pigments, and lead(IV) oxide (PbO₂), a strong oxidant in batteries.[9] Lead sulfide (PbS), known as galena, is its principal ore and appears as a dense, metallic gray mineral.[11] These compounds are noted for toxicity, with lead accumulating in biological systems and disrupting enzymatic functions, as evidenced by blood lead levels above 5 μg/dL correlating with neurological effects in epidemiological studies.[10] Polybutylene (PB or PB-1), a saturated polyolefin polymer with repeating units (C₄H₈)ₙ, is synthesized via Ziegler-Natta polymerization of 1-butene monomer.[12] This thermoplastic exhibits high crystallinity, a glass transition temperature of -20 to -30 °C, and melting range of 115–135 °C, conferring stiffness, creep resistance, and impact strength superior to polyethylene in some applications.[13] PB pipes, introduced in the 1970s, gained use in plumbing for flexibility and corrosion resistance but showed premature failure rates exceeding 50% in chlorinated water systems due to oxidative degradation, prompting class-action lawsuits and phased withdrawals by the 1990s.[14] Chemically inert under neutral conditions, PB hydrolyzes slowly in acidic or basic environments, limiting its durability in varied service conditions.[15]Computing and technology
Data storage and units
In computing, the petabyte (PB) denotes a unit of digital information storage equivalent to one quadrillion bytes, or $10^{15} bytes, following the decimal (SI) prefix system where each prefix multiplies by 1,000. This definition aligns with standards for measuring data capacities in storage devices, such as hard drives, where manufacturers typically report capacities using decimal prefixes to reflect the physical encoding density.[16] For context, 1 PB equals 1,000 terabytes (TB) or 1,000,000 gigabytes (GB), enabling the quantification of vast datasets like those in enterprise archives or cloud services.[17] However, a distinction exists between decimal and binary interpretations due to computing's base-2 architecture. In binary systems, the equivalent unit is the pebibyte (PiB), defined by the International Electrotechnical Commission (IEC) as $2^{50} bytes, or precisely 1,125,899,906,842,624 bytes, which is about 13% larger than 1 PB.[18] The IEC introduced binary prefixes like pebi- in 1998 to resolve ambiguities, as operating systems and memory often calculate sizes in powers of 2 (e.g., 1,024 rather than 1,000), leading to discrepancies where advertised PB capacities appear smaller when formatted.[19] Despite this, "PB" remains predominantly used for the decimal variant in marketing and specifications, while PiB sees limited adoption outside technical standards bodies.[20] The petabyte scale emerged in the late 1990s and early 2000s as data volumes exploded with the internet and digital media, surpassing terabyte thresholds in applications like scientific simulations and large-scale databases.[21] For instance, genomic sequencing projects or global internet archives often operate at PB levels, underscoring the unit's role in big data infrastructure.[22] Standardization efforts by bodies like NIST and IEC emphasize precise usage to avoid misrepresentations, particularly in contractual or performance contexts where binary realities affect effective capacity.[19][18]Hardware and software
Packard Bell, often abbreviated as PB, was a prominent brand in personal computer hardware during the late 1980s and 1990s, specializing in affordable desktop and laptop systems targeted at home users and small businesses. The company's PCs typically featured Intel processors, such as the 386 and 486 series, bundled with proprietary motherboards like the PB450 based on the OPTi 82C895 chipset for energy-efficient operation, and included pre-installed software such as DOS and multimedia applications to appeal to non-technical consumers.[23] By the mid-1990s, Packard Bell held a significant market share in the U.S. consumer PC segment, with models like the PB 1700CD utilizing 486DX2 CPUs for multimedia capabilities, though the brand faced criticism for using lower-quality components and limited upgradability compared to competitors like Dell or Gateway.[24] The PC division was acquired by NEC in 1996, after which the PB branding continued in Europe under Acer ownership until its phase-out in the early 2000s.[25] In software, PowerBuilder (PB) is a rapid application development platform designed for creating data-driven business applications, particularly those involving client-server architectures and database connectivity. Originally released by Powersoft in 1991, it employs a visual, declarative programming model that allows developers to build CRUD (create, read, update, delete) interfaces with SQL databases like Oracle or SQL Server, using DataWindows for data presentation and manipulation.[26] Acquired by Sybase in 1994 and later by SAP, PowerBuilder has evolved to support web and mobile deployment, with version 2025 introducing enhanced IDE features, REST API generation, and codeless UI updates for modernizing legacy applications.[26] Despite competition from web-based tools, it remains in use for enterprise systems due to its efficiency in handling complex data forms, though maintenance of older PB codebases poses challenges amid shifting developer skills toward JavaScript frameworks.[27] Protocol Buffers (PB), developed by Google, is a language-neutral serialization format for efficient data exchange in software systems, defining structured messages in .proto files that compile into code for languages like C++, Java, and Python. Introduced in 2008, PB enables compact binary encoding for high-performance applications such as gRPC services and distributed systems, outperforming XML or JSON in speed and size for protocols like those in Android or TensorFlow.[28] Its schema evolution support allows backward-compatible changes without breaking existing implementations, making it suitable for microservices and API communications where reliability and low latency are critical.Other technological uses
In electronics manufacturing, PB designates a printed board, defined as the general term for a completely processed printed circuit configuration or printed wiring configuration, encompassing single-sided, double-sided, and multilayer boards with or without plated-through holes.[29] This terminology originates from industry standards like those from IPC, distinguishing PB as a broader category for bare boards prior to component assembly, contrasting with more specific terms like printed wiring board (PWB) or printed circuit board (PCB).[30] PunkBuster, abbreviated as PB in its installation directories and utilities, is an anti-cheat software developed by Even Balance, Inc., designed to detect and prevent cheating in online multiplayer games by scanning process memory and file integrity.[31] First integrated into commercial titles around 2000, it gained prominence in franchises such as Battlefield and Call of Duty, employing client-server architecture where the PB client on user machines communicates with PB servers to enforce fair play through automated bans.[32] Despite its effectiveness in early 2000s gaming, PunkBuster has faced obsolescence critiques due to evolving cheat methods and reduced support in modern titles post-2015.[33] In control systems technology, PB refers to proportional band, a parameter in proportional-integral-derivative (PID) controllers that defines the range of input variation over which the output changes proportionally, typically expressed as a percentage of the full sensor span to minimize offset in industrial automation processes.[34] This usage dates to mid-20th-century analog control engineering and persists in programmable logic controllers (PLCs) for applications like temperature regulation and motor speed control.[35]Economics and business
Financial and economic terms
The price-to-book (P/B) ratio, commonly abbreviated as PB ratio, is a financial metric that compares a company's market capitalization to its book value of equity, providing insight into whether a stock is undervalued or overvalued relative to its net asset value.[36] Book value represents the net asset value of a company as recorded on its balance sheet, calculated as total assets minus total liabilities, often adjusted per share.[37] This ratio is particularly useful for value investors assessing asset-intensive industries such as banking, insurance, or manufacturing, where tangible assets form a significant portion of value, though it is less applicable to service-oriented or technology firms with high intangible assets like intellectual property.[38] The formula for the P/B ratio is derived by dividing the current market price per share by the book value per share, or equivalently, market capitalization by total book value of equity:\text{P/B Ratio} = \frac{\text{Market Price per Share}}{\text{Book Value per Share}}
Book value per share is computed as (total shareholders' equity) divided by the number of outstanding shares.[36] For example, if a company's stock trades at $50 per share with a book value per share of $25, the P/B ratio is 2.0, indicating the market values the company at twice its accounting net assets.[37] Adjustments may be made for tangible book value, excluding intangibles like goodwill, to better reflect liquidation value in distressed scenarios.[36] Interpretation of the P/B ratio varies by context and industry benchmarks; a ratio below 1 suggests potential undervaluation, as the market price is less than the company's recorded net assets, possibly signaling financial distress or overlooked assets, while a ratio above 1 implies the market anticipates growth beyond current book value.[37] Sector averages provide comparative context: as of recent data, U.S. banking firms often trade at P/B ratios around 1.0-1.5, reflecting regulatory capital requirements, whereas technology sectors may exceed 5.0 due to growth expectations.[39] Investors like Warren Buffett have historically favored low P/B stocks for value strategies, but the metric's effectiveness diminishes in inflationary environments or when book values are outdated due to historical cost accounting.[40] Limitations include its reliance on historical accounting data, which may not capture future earning potential or off-balance-sheet assets, and vulnerability to manipulation through accounting practices like asset write-downs.[38] Negative book values, common in loss-making firms, render the ratio meaningless or negative, and it performs poorly for companies with significant intangible assets, as seen in critiques during the dot-com era where high P/B ratios preceded bubbles.[40] Thus, P/B is best used alongside metrics like price-to-earnings (P/E) or return on equity (ROE) for a holistic valuation, with empirical studies showing its predictive power strongest in stable, asset-backed sectors.[37]