PSP
Progressive supranuclear palsy (PSP) is a rare, progressive neurodegenerative disorder classified as a tauopathy, in which abnormal aggregates of tau protein accumulate in neurons, glia, and other brain cells, primarily affecting regions responsible for movement, balance, and eye control.[1][2][3] First described as a distinct clinicopathologic entity in 1964 by neurologists J.C. Steele, J.C. Richardson, and E. Olszewski, PSP typically manifests in individuals over age 60, with initial symptoms often including unexplained falls due to postural instability, axial rigidity, and vertical gaze palsy that hinders downward eye movement.[4][5][1] Unlike Parkinson's disease, where resting tremor predominates early, PSP features minimal tremor and rapid progression to severe disability, including dysphagia, dysarthria, and frontal cognitive deficits such as apathy and executive dysfunction.[1][2][3] Diagnosis relies on clinical criteria, supported by neuroimaging showing midbrain atrophy (the "hummingbird sign" on MRI), but PSP is frequently misdiagnosed as Parkinson's disease or other atypical parkinsonisms in early stages due to overlapping motor symptoms and lack of definitive biomarkers during life.[4][2][6] No disease-modifying treatments exist, with management limited to symptomatic relief through physical therapy, levodopa (often ineffective), and palliative care; median survival post-symptom onset is 6 to 10 years, primarily limited by aspiration pneumonia and immobility.[7][2][1]Gaming and Entertainment
PlayStation Portable
The PlayStation Portable (PSP) is a handheld video game console developed and marketed by Sony Computer Entertainment as the first portable entry in the PlayStation brand.[8] It was first released in Japan on December 12, 2004, followed by North America on March 24, 2005, and European and other PAL regions on September 1, 2005.[8][9] Development of the PSP was announced at E3 2003, with a formal unveiling on May 11, 2004, prior to E3 2004.[10] Positioned as a competitor to Nintendo's Dual Screen (DS), the PSP emphasized high-fidelity graphics approaching PlayStation 2 levels, multimedia capabilities, and online connectivity, rather than dual-screen touch interfaces.[11] The console features a MIPS R4000-based CPU clocked at 333 MHz, 32 MB of main RAM (upgraded to 64 MB in later models), and 4 MB of embedded DRAM including 2 MB dedicated to graphics processing.[10][12] Its custom GPU supports resolutions up to 480x272 on a 4.3-inch LCD screen, enabling video playback and rendering effects comparable to the PlayStation 2 in optimized titles.[11] Media is loaded via Universal Media Disc (UMD), a proprietary 64 mm optical disc format with 1.8 GB capacity per side, designed for games, movies, and audio.[13] Wireless networking via Wi-Fi supports ad-hoc multiplayer, internet browsing, and digital downloads, though early models lacked full backward compatibility with PlayStation 1 titles until firmware updates.[10] Sony released several hardware revisions to address battery life, weight, and features. The original PSP-1000 model, weighing 280 grams, included a robust build but shorter battery duration of about 4-6 hours for gameplay.[14] The PSP-2000 (slim and lite) in 2007 reduced weight to 189 grams, improved battery life to 6-8 hours, and added composite video output, though it dimmed the screen slightly compared to the original.[14] The PSP-3000 in 2008 enhanced screen brightness and color accuracy while maintaining the slim form.[14] The PSP Go, launched in 2009, featured a sliding screen, no UMD drive, 16 GB internal flash storage, and Bluetooth, targeting digital distribution but at higher cost and without physical media support.[14] The budget PSP-E1000 (PSP Street) in 2011 omitted Wi-Fi and microphone features for a lower price point in select regions.[14] The PSP library comprises over 1,900 games, spanning genres from action-adventure to RPGs, with strong ports of console titles like God of War: Chains of Olympus and original handheld-exclusive entries.[15] Best-selling titles include Grand Theft Auto: Liberty City Stories with 8 million units and Grand Theft Auto: Vice City Stories with 5.03 million.[16] UMDs also supported movie releases from studios, though adoption was limited by the format's proprietary nature and competition from digital streaming.[13] System software updates expanded functionality, including remote PlayStation 3 control and PSN integration for downloads. Cumulative sales reached 76.4 million units worldwide as of March 31, 2012, per Sony reports, with independent estimates placing lifetime totals near 80-82 million.[17][18] Shipments ceased globally by the end of 2014, following a focus shift to the PlayStation Vita successor announced in 2011.[19] UMD production ended in 2016 with the closure of the last Japanese factory.[13] Despite discontinuation, the PSP influenced portable gaming by demonstrating viability of powerful handhelds, though its proprietary media and high price relative to competitors like the DS contributed to mixed market performance outside Japan.[19]Medicine and Biology
Progressive Supranuclear Palsy
Progressive supranuclear palsy (PSP) is a rare, progressive neurodegenerative disorder characterized by the accumulation of abnormal tau protein in neurons and glia, leading to neuronal loss primarily in the midbrain, basal ganglia, and frontal cortex.[20] It manifests as an atypical parkinsonian syndrome with prominent early postural instability, vertical gaze palsy, and axial rigidity, distinguishing it from idiopathic Parkinson's disease.[1] Symptoms typically emerge in individuals aged 60 or older, progressing relentlessly and resulting in severe disability within 3-5 years.[5] Core motor symptoms include early falls due to impaired balance and gait, often backward, with axial more than appendicular rigidity and bradykinesia that responds poorly to levodopa.[3] Oculomotor dysfunction is hallmark, featuring supranuclear vertical gaze palsy—initially downgaze limitation, progressing to complete ophthalmoplegia—along with square-wave jerks and lid retraction.[1] Non-motor features encompass pseudobulbar affect, dysphagia, dysarthria, and frontal cognitive deficits such as apathy, executive dysfunction, and impaired verbal fluency, with up to 70% of cases showing dementia-like changes.[21] Subtypes include Richardson syndrome (most common, with gaze palsy and falls) and PSP-parkinsonism (more limb-dominant initially).[20] The pathology involves hyperphosphorylated, 4-repeat isoform tau forming neurofibrillary tangles, tufted astrocytes, and coiled bodies, concentrated in subcortical structures like the subthalamic nucleus and substantia nigra, with cortical involvement explaining behavioral symptoms.[20] Causally, tau misfolding propagates prion-like, disrupting microtubule stability and axonal transport, though the initiating trigger remains unknown; most cases are sporadic, with rare familial links to MAPT gene mutations.[1] Environmental factors are unestablished, and it is not linked to Lewy bodies or alpha-synuclein as in Parkinson's.[5] Diagnosis relies on clinical criteria, such as the Movement Disorder Society PSP criteria requiring progressive supranuclear gaze palsy or slowed vertical saccades plus compatible symptoms, supported by MRI showing midbrain atrophy (hummingbird sign) and excluding alternatives like multiple system atrophy.[22] DaTscan may show reduced striatal dopamine uptake, but levodopa unresponsiveness and early autonomic sparing aid differentiation from Parkinson's.[7] CSF tau biomarkers and PET imaging for tau deposition are emerging but not routine.[23] No disease-modifying treatments exist; management is symptomatic, with cautious levodopa trials (up to 50% partial response in some) for bradykinesia, though dyskinesias limit utility.[22] Botulinum toxin addresses dystonia, physical therapy prevents contractures, and speech therapy manages dysphagia to reduce aspiration pneumonia risk.[7] Recent phase II/III trials (2023-2025) target tau aggregation, including microtubule stabilizers like those in the PROSPER study (completed recruitment October 2025 for early PSP-RS) and platform trials evaluating anti-tau antibodies and kinase inhibitors.[24] [25] Epidemiologically, PSP affects 3-6 individuals per 100,000 worldwide, with incidence around 1-3 per 100,000 person-years, higher in males (1.5:1 ratio) and increasing with age; global prevalence is 5-6.4 per 100,000, potentially rising due to better recognition.[26] [27] Median survival is 6-9 years post-diagnosis, primarily from falls, infections, or respiratory failure, underscoring the need for multidisciplinary care.[28]Phenolsulfonphthalein
Phenolsulfonphthalein, commonly known as phenol red, is a synthetic triphenylmethane dye with the chemical formula C₁₉H₁₄O₅S and a molecular weight of 354.38 g/mol. It appears as a red crystalline solid with low solubility in water (approximately 0.77 g/L) and greater solubility in ethanol (2.9 g/L), and it decomposes at temperatures above 300 °C without a defined melting point.[29] As a pH-sensitive compound, it undergoes a reversible color transition from yellow in acidic conditions (pH < 6.8) to red in alkaline conditions (pH > 8.2), a property exploited in laboratory applications such as monitoring pH in cell culture media.[30] In medicine, phenolsulfonphthalein serves as a diagnostic agent primarily in the evaluation of renal function through the phenolsulfonphthalein (PSP) excretion test.[31] The compound is actively secreted by the proximal tubules of the kidney, with approximately 50-60% extracted per pass through the renal circulation and a maximal tubular excretory rate of about 36 mg/min per 1.73 m² body surface area in humans.[32] This allows the test to provide insights into effective renal plasma flow and tubular secretory capacity, distinguishing it from glomerular filtration-based assessments. About 80% of the dye is excreted by the kidneys and 20% by the liver, making it sensitive to impairments in either organ, though its primary utility lies in detecting renal pathology.[32] The PSP test was introduced in 1910 by Leonard G. Rowntree and John T. Geraghty, originating from investigations into potential subcutaneous purgatives where the dye's rapid renal clearance and low toxicity were noted.[33] In the standard procedure, a 6 mg dose is administered intravenously or intramuscularly after the patient empties the bladder; subsequent urine samples are collected at 15, 30, 60, and 120 minutes post-injection, with the dye quantified colorimetrically or spectrophotometrically after alkalinization to enhance visibility.[31] Complete urine collection is essential for accuracy, as incomplete voids can underestimate excretion rates. The test has been largely supplanted by modern metrics like glomerular filtration rate (GFR) estimation via creatinine clearance or inulin clearance due to its invasiveness and the need for timed collections, but it retains niche value in specific urologic evaluations where tubular function is paramount.[33] Adverse effects are uncommon but may include hypersensitivity reactions such as rash, itching, or wheezing, necessitating immediate medical attention.[31] Precautions include avoiding use in patients with known allergies to the dye, severe liver disease, or conditions like gout or multiple myeloma that could confound results; hydration is encouraged pre- and post-test to facilitate excretion.[31] While effective for historical renal assessment, the test's clearance averages around 400 mL/min in healthy individuals, reflecting robust tubular handling, but diminished recovery signals potential dysfunction requiring further investigation.[32]Computing and Software
Personal Software Process
The Personal Software Process (PSP) is a structured, self-improvement framework for individual software engineers, emphasizing disciplined planning, measurement, and review to enhance personal development practices and produce higher-quality software. Developed by Watts S. Humphrey at the Software Engineering Institute (SEI) of Carnegie Mellon University starting in 1993, the PSP builds on principles of process maturity to enable engineers to track their performance, reduce defects, and improve estimation accuracy through empirical data collection rather than intuition.[34][35] It serves as a foundational precursor to team-level approaches like the Team Software Process (TSP), focusing first on individual discipline to ensure scalable organizational improvements.[36] Core to the PSP are its progressive levels, each introducing specific methods, forms, and scripts for process refinement. At PSP Level 0 (PSP0), engineers establish a baseline by logging time spent on planning, design, coding, compiling, testing, and postmortem analysis for small programs, while tracking defects to quantify current performance without predefined standards.[35] PSP Level 1 (PSP1) adds coding standards, such as style conventions and checklists, along with personal code reviews and compile/test defect logging to identify injection points and prioritize prevention. PSP Level 2 (PSP2) incorporates design phases with templates for structure and proxy-based size estimation (e.g., using lines of code or function points from historical data), enabling commitments based on earned value and yield metrics like defects per thousand lines of code. PSP Level 3 (PSP3) extends to larger-scale scripting, advanced planning with decomposition, and integration with tools for automated measurement, aiming for defect rates below 1 per 100 lines of code through iterative refinement.[34] These levels use standardized forms for time recording, defect classification (by type and phase), and size measurement, fostering a data-driven cycle of plan, execute, review, and adjust. Implementation involves tailoring the process to personal needs via eight steps: assessing priorities, defining objectives, selecting methods, prototyping scripts, piloting, analyzing results, standardizing, and reviewing for improvement. Engineers collect metrics on productivity (e.g., size per time unit), quality (defect density), and predictability (estimation variance), using them to set verifiable commitments and review deviations in postmortems. The PSP promotes defect prevention over detection by mandating personal reviews before compilation or testing, with evidence from SEI courses showing practitioners reducing review escapes by focusing on high-leverage phases like design.[34] Tools such as spreadsheets or specialized software support data analysis, though the framework prioritizes manual discipline to build intrinsic habits. Empirical evidence from SEI studies and applications indicates PSP yields measurable gains: engineers typically achieve 5-10 times fewer post-review defects, estimation accuracy within 20% variance, and productivity increases of 20-50% through reduced rework, as validated in controlled exercises with over 100 participants across PSP training.[37] A 1997 SEI technical report on PSP's impact found median defect reductions of 60% after Level 1 adoption, with sustained quality improvements tied to consistent measurement rather than innate skill.[35] However, adoption requires 100-200 hours of initial training and discipline, with benefits most evident in structured environments; anecdotal reports note challenges in dynamic or non-coding tasks, though core principles apply broadly to defined activities.[38] Humphrey's foundational texts, including the 1995 book PSP: A Discipline for Software Engineering, provide detailed scripts and case data supporting these outcomes from early pilots at IBM and elsewhere.[39]Paint Shop Pro
Paint Shop Pro is a proprietary raster graphics editor designed for image creation and manipulation on Microsoft Windows platforms. Originally developed by Jasc Software, Inc., it originated as shareware software that competed with more expensive professional tools by offering accessible bitmap editing capabilities.[40][41] The software's initial version, released in 1990 under the name Paint Shop, was created by Jasc founder Robert Voit as a tool for converting graphics file formats, evolving into a full-featured editor through iterative updates distributed via shareware models that built a user base among hobbyists and semi-professionals.[40][42] By the early 2000s, versions like Paint Shop Pro 7 (2001) included advanced features such as layers and scripting support, positioning it as a budget alternative to Adobe Photoshop.[43] In October 2004, Corel Corporation acquired Jasc Software for an undisclosed sum, integrating Paint Shop Pro into its portfolio and rebranding it as Corel PaintShop Pro starting with version X in 2005.[44][45] Core features encompass selection tools, brushes, filters, text handling, and support for plugins compatible with Adobe Photoshop formats, alongside RAW image processing via integrated labs in later editions.[46] Recent iterations, such as the 2023 release, incorporate AI-driven enhancements including focus stacking, frame tools, and automated upsampling for higher-resolution outputs without sacrificing detail.[47] The software supports non-destructive editing through adjustment layers and maintains compatibility with Windows updates, though it lacks cross-platform availability.[48] Following Corel's acquisition by Alludo in 2023, PaintShop Pro's development has emphasized subscription-free perpetual licenses, but no major version updates have been confirmed beyond 2023 as of October 2025, reflecting a strategic pivot amid market shifts toward cloud-based editing suites.[48] Its enduring appeal lies in one-time purchase affordability and comprehensive toolsets for photo retouching, compositing, and graphic design, though users note occasional performance lags on high-resolution files compared to vector-focused competitors.[49]Other Computing Uses
In computing, PSP refers to the AMD Platform Security Processor, a dedicated ARM-based microcontroller integrated into AMD x86 processors starting with the 2013 Richland APUs and continuing in subsequent architectures such as Zen-based CPUs.[50] This subsystem operates independently from the primary x86 cores, managing secure boot processes, cryptographic key handling, firmware verification, and runtime security services to isolate sensitive operations from the main operating system.[51] The PSP initializes before the x86 cores, loading firmware from off-chip storage via an on-chip bootloader, and has been rebranded as the AMD Secure Processor in later documentation, though retaining core functionalities for trusted execution environments.[50] Another application is the PSP Security Protocol developed by Google for large-scale data center encryption. Introduced internally at Google and open-sourced on May 19, 2022, PSP is a transport-independent protocol that offloads encryption and decryption to network interface cards (NICs), reducing CPU overhead for in-transit data protection.[52] Drawing concepts from IPsec ESP, it supports hardware-accelerated packet encryption across connections, with Linux kernel support upstreamed for integration starting in version 6.18 on September 21, 2025.[53] The protocol's recursive acronym emphasizes its focus on efficient, scalable security without relying on general-purpose processors for crypto operations.[54] In server management, PSP denotes the HP ProLiant Support Pack, a suite of OS-specific drivers, utilities, firmware updates, and management agents tailored for Hewlett-Packard (later HPE) ProLiant servers. Released in versions such as PSP 9.00 for RHEL5 in the mid-2000s, it facilitated system health monitoring, storage management, and remote administration, with installations often creating boot entries via tools like GRUB.[55] By 2012, HP transitioned to the consolidated Service Pack for ProLiant (SPP), which absorbed PSP components into ISO-based deployments for streamlined firmware and driver updates across ProLiant generations.[56] This evolution addressed complexities in maintaining server stability and compatibility, though legacy PSP installs required careful selection to avoid redundant or conflicting components.[57]Organizations and Politics
Political Parties
The Progressive Socialist Party (PSP) of Lebanon, founded on May 5, 1949, by Kamal Jumblatt, emerged as a proponent of secular democratic socialism and social reform, drawing initial support from diverse sects despite its strong Druze confessional base in Mount Lebanon.[58] The party advocated progressive change, including land reform and opposition to feudalism, and expanded influence through alliances in Lebanon's confessional political system. During the 1975–1990 civil war, the PSP formed the People's Liberation Army militia, aligning with leftist and Palestinian factions against right-wing forces, which resulted in territorial control in Druze areas like the Chouf Mountains but also sectarian clashes.[58] Following Jumblatt's assassination on March 16, 1977, leadership transitioned to his son Walid Jumblatt, under whom the party participated in post-war governments, the 2005 Cedar Revolution opposition coalition, and the March 14 Alliance, while maintaining a socialist orientation amid Lebanon's patronage-driven politics.[59] The Progress Singapore Party (PSP), established on January 18, 2019, by Tan Cheng Bock—a physician and former People's Action Party MP who lost the 2011 presidential election—aims to offer policy alternatives and enhance parliamentary oversight in Singapore's dominant-party system.[60] Contesting the 2020 general election primarily in West Coast Group Representation Constituency, the PSP garnered 48.31% of votes there, securing two Non-Constituency MP seats for Leong Mun Wai and Hazel Poa as the best-performing losers under Singapore's electoral rules.[60] The party emphasized issues like healthcare affordability, job security for older workers, and immigration management, positioning itself as centrist-progressive rather than ideologically rigid. In the July 2025 general election, however, it achieved a weaker performance, failing to retain NCMP seats amid competition from other opposition groups, prompting a leadership shake-up on July 5, 2025, with Leong Mun Wai assuming secretary-general duties and A'bas bin Kasmani as chairman.[61] The Puerto Rican Socialist Party (PSP), formed on November 28, 1971, from the Pro-Independence Movement, pursued Marxist-Leninist goals of Puerto Rican independence from the United States through revolutionary socialism, emphasizing anti-imperialism and worker mobilization.[62] It operated as a cadre organization rather than a mass electoral party, focusing on grassroots activism and solidarity with Latin American leftist movements, but dissolved by the mid-1990s amid internal divisions and waning support. Historical entities like the Netherlands' Pacifistisch-Socialistische Partij (1957–1989), a pacifist socialist group that merged into broader left coalitions, and India's Praja Socialist Party (1952–1972), a democratic socialist merger of earlier parties, also used the PSP acronym but ceased independent existence decades ago.[63]Government and Public Sector Bodies
The Pennsylvania State Police (PSP) serves as the primary statewide law enforcement agency for the Commonwealth of Pennsylvania in the United States. Established on October 1, 1905, by Governor Samuel W. Pennypacker, it was the first uniformed police organization of its kind in the nation, initially tasked with suppressing rural crime and civil unrest amid industrialization and labor strife. Today, the PSP maintains approximately 4,800 sworn troopers organized into 16 troops across the state, handling duties such as highway patrol, criminal investigations, emergency response, and support to local agencies lacking resources.[64] Its jurisdiction extends to unincorporated areas and supplements municipal policing, with specialized bureaus for aviation, forensics, and intelligence.[65] In Portugal, the Polícia de Segurança Pública (PSP), or Public Security Police, functions as the country's national civil police force, focusing on urban public order and security. Formed in 1867 as a centralized body under the Ministry of Internal Administration, it operates in major cities and towns, enforcing laws, preventing crime, and managing traffic while coordinating with the Republican National Guard for rural duties.[66] The PSP employs over 20,000 personnel and maintains a presence through community policing units, specialized intervention groups, and border control roles, emphasizing preventive patrols and rapid response to disturbances.[67] Other public sector entities using the PSP acronym include the Puget Sound Partnership, a Washington State agency created by legislation in 2007 to coordinate restoration efforts for the Puget Sound ecosystem, involving collaboration among state, federal, tribal, and local governments to address pollution, habitat loss, and species recovery.[68] These bodies reflect varied applications of the acronym in law enforcement and environmental governance, distinct from private or commercial uses.Finance and Investment
PSP Investments
The Public Sector Pension Investment Board, operating as PSP Investments, is a Canadian Crown corporation established to manage the investments of defined benefit pension plans for federal public service employees, members of the Canadian Forces, and the Royal Canadian Mounted Police.[69] Its mandate focuses on achieving optimal long-term returns within acceptable risk levels to ensure the sustainability of these plans, operating independently from the government while reporting to Parliament through the Minister of National Revenue.[70] PSP Investments was created by the Public Sector Pension Investment Board Act in 1999, with operations commencing in 2000 initially limited to public markets and fixed income asset classes.[71] Over time, PSP Investments expanded its investment capabilities to diversify beyond traditional assets, incorporating real estate in 2003, private equity in 2004, infrastructure in 2006, natural resources in 2011, and private debt in 2015.[71] This evolution supported asset growth milestones, including net assets under management reaching CAD $50 billion in 2011, $100 billion in 2015, and $150 billion in 2018.[71] Headquartered in Montreal, the organization established international offices in New York in 2015, London in 2016, and Hong Kong in 2019 to access global opportunities.[71] By its 25th anniversary on April 1, 2025, PSP Investments had generated cumulative net income of $205 billion.[71] As of March 31, 2025, PSP Investments managed net assets of CAD $299.7 billion, marking a 13.2% increase from the prior fiscal year and positioning it as the third-largest among Canada's public pension investors.[72] The fiscal 2025 net return was 12.6%, with a five-year annualized net return of 10.6%.[70] Its investment approach emphasizes innovation, collaboration, and agility in pursuing opportunities across asset classes, including public equities, private markets, and real assets, while prioritizing risk-adjusted returns over benchmarks.[73] Asset allocation as of March 31, 2025, reflected a balanced portfolio diversified to mitigate volatility:| Asset Class | Percentage |
|---|---|
| Capital Markets | 48.7% |
| Private Equity | 13.6% |
| Infrastructure | 10.7% |
| Real Estate | 9.5% |
| Credit | 8.2% |
| Natural Resources | 5.1% |
| Other | 4.2% |
Engineering and Technology
Photostimulable Phosphor
Photostimulable phosphor (PSP), also known as storage phosphor, is a material that temporarily stores energy from incident ionizing radiation, such as x-rays, in electron traps within its crystal lattice, subsequently releasing the energy as visible light upon stimulation by a lower-energy light source, typically a laser.[75] This photostimulated luminescence (PSL) process enables the capture of radiographic images without the need for traditional film development.[76] The mechanism relies on the promotion of electrons from valence to conduction bands by absorbed x-ray photons, followed by trapping in metastable states; laser stimulation then frees these electrons, producing light proportional to the stored radiation dose.[77] The foundational PSP material, barium fluorobromide doped with europium (BaFBr:Eu²⁺), was identified in the late 1970s by researchers at Fuji Photo Film Co. for use in medical imaging, marking the basis for computed radiography systems commercialized in the 1980s.[76] Earlier explorations of storage phosphors date to radiation dosimetry applications, but the adaptation to high-resolution imaging stemmed from the need to digitize x-ray detection while retaining compatibility with existing radiographic workflows.[78] Cesium bromide doped with europium (CsBr:Eu²⁺) emerged later as an alternative, offering improved resolution due to its needle-like crystal structure that reduces light scattering.[76] PSP plates consist of a flexible substrate coated with a phosphor layer, typically 100–500 micrometers thick, embedded in a binder, and protected by a durable outer layer; the phosphor crystals, often around 1–5 micrometers in size, trap x-ray energy with quantum efficiency approaching 1 for diagnostic energies (20–150 keV).[79] After exposure, the plate is scanned by a red helium-neon laser (633 nm wavelength), erasing residual signal with white light to allow reuse up to thousands of cycles, though sensitivity degrades over time from mechanical wear or contamination.[77] In computed radiography, PSP serves as the detector in cassette-based systems, enabling wide dynamic range (over 10,000:1) and post-exposure latitude adjustments that reduce retakes compared to film, with radiation doses typically 20–50% lower due to optimized exposure indexing.[80] Applications extend beyond medical diagnostics to industrial non-destructive testing, security screening, and personnel dosimetry, where stored signals quantify radiation exposure over extended periods.[81] Drawbacks include lower spatial resolution (5–10 line pairs per millimeter) versus direct digital detectors, attributed to lateral light diffusion during readout, and the need for manual plate handling, which introduces artifact risks from scratches or improper erasure.[82][83] Despite these, PSP's reusability and lower upfront costs sustain its role in resource-limited settings as of 2023.[84]Firearms and Military
Firearms Models
The Heckler & Koch PSP, denoting Polizei Selbstladepistole or Police Self-loading Pistol, represents an early variant in the P7 series of semi-automatic pistols, developed in the 1970s to meet West German police requirements for a compact 9×19mm Parabellum handgun.[85][86] This model emerged from trials at the Lübeck Border Police Academy, where initial prototypes addressed challenges like carbon buildup and overheating through refinements such as wiper rings on the gas piston.[86] Approximately 250 units were produced under the PSP designation, with serial numbers up to 239 considered original examples, before transitioning to the pre-production P7 starting at serial 240.[86] The PSP employs a gas-delayed blowback mechanism with a fixed, cold hammer-forged barrel featuring polygonal rifling for enhanced accuracy and reduced wear.[87][85] Its signature feature is the squeeze-cocking grip, where levers in the front strap cock the striker upon compression, enabling a light single-action trigger pull without a traditional manual safety; an automatic firing pin block provides additional security.[87][86] The all-steel construction, low-profile slide, and 110-degree grip angle contribute to controllability and a natural point of aim, while the European-style heel magazine release distinguishes early PSPs from later U.S.-market adaptations.[85][87]| Specification | Detail |
|---|---|
| Caliber | 9×19mm Parabellum |
| Magazine Capacity | 8 rounds (single-stack) |
| Barrel Length | 105 mm (4.13 in) |
| Overall Length | 171 mm (6.73 in) |
| Height | 127 mm (5.00 in) |
| Weight (empty) | 780–850 g (1.72–1.87 lb) |
| Action | Gas-delayed blowback, striker-fired |
| Sights | Fixed, 3-dot (later models) |