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DPD

(DPD) is a Cluster C defined by a pervasive and excessive need to be taken care of that leads to submissive and clinging behavior, as well as fears of separation, typically emerging by early adulthood and manifesting across various contexts.
Diagnosis requires at least five of eight criteria, including difficulty making everyday decisions without excessive advice from others, discomfort when alone due to exaggerated fears of inability to care for oneself, urgency in starting new relationships upon the close of significant ones, and preoccupation with fears of being left to fend for oneself.
Epidemiological studies estimate at 0.5-0.6% in the general , with somewhat higher rates among women (0.6%) than men (0.4%) and peaking in younger adults aged 18-29 (0.9%).
appears multifactorial, involving genetic vulnerabilities, childhood factors such as illness or parental overprotection fostering separation anxiety, and temperamental traits like high and reward dependence.
DPD often co-occurs with depressive, anxiety, and substance use disorders, elevating risks for interpersonal abuse, suicidality, and poor health outcomes, though traits may attenuate with age and therapeutic intervention.
Treatment relies on , with cognitive-behavioral and psychodynamic modalities demonstrating preliminary benefits in building and , while targets comorbidities via SSRIs or SNRIs absent specific FDA approvals for DPD.
Despite its inclusion in diagnostic manuals, DPD remains understudied, with empirical research highlighting methodological flaws in earlier work, inconsistencies between DSM criteria and observed dependency traits, and broader critiques of categorical models favoring dimensional alternatives for better validity.

Computing

Dead Peer Detection

Dead Peer Detection (DPD) is a mechanism defined in RFC 3706 for identifying unresponsive () peers in VPN deployments. It uses Informational Exchange messages containing R-U-THERE and R-U-THERE-ACK payloads to probe peer liveness without requiring separate protocols. By leveraging existing traffic patterns, DPD minimizes unnecessary messaging overhead compared to constant heartbeats. The protocol supports two operational modes to balance detection speed and resource use: periodic mode, which sends probes at configurable fixed intervals (e.g., every 10-30 seconds), and (or on-idle) mode, which initiates probes only after a timeout period of traffic inactivity (typically 20-120 seconds). In periodic mode, a device transmits an unsolicited R-U-THERE message and expects an R-U-THERE-ACK response; failure to receive acknowledgments after a (e.g., 5 retries) declares the peer dead. On-demand mode defers probing until idle, reducing bandwidth in active tunnels but risking delayed detection during sudden failures. Upon detecting a dead peer, the local device deletes the security association (SA) and any associated child SAs, clearing stale state to avoid traffic blackholing and facilitating automatic rekeying or tunnel re-establishment. Peers negotiate DPD enablement, interval, and retry parameters during IKE Phase 1 authentication, with defaults varying by implementation (e.g., enabled by default in Junos for peers). Vendor-specific extensions enhance DPD; for instance, Cisco routers support configurable periodic message options to query IKE peer liveliness explicitly, while Fortinet devices allow on-idle flushing of idle tunnels post-DPD failure. This feature improves VPN reliability in site-to-site setups by enabling proactive failure response, though periodic modes can introduce minor overhead in low-traffic environments.

Densely Packed Decimal

Densely packed decimal (DPD) is a lossless binary encoding method that compresses three digits (ranging from 000 to 999) into 10 bits, achieving greater density than (BCD), which uses 4 bits per for a total of 12 bits per three digits. This encoding was developed by Mike F. Cowlishaw and published in 2002, enabling efficient representation of numbers while preserving boundaries for arithmetic operations such as and . By classifying digits as small (0–7, encodable in 3 bits) or large (8–9, requiring an extra indicator bit), DPD employs a Huffman-like scheme with prefix bits to signal digit types, followed by the digit values. DPD refines the 1975 Chen-Ho encoding by relocating prefix bits to allow right-aligned packing, which supports arbitrary-length decimal strings without the multiple-of-three-digit restriction of its predecessor. For instance, the sequence 005 encodes to the 10-bit value 0000000101, while encodes to 0011111111; these can be concatenated for longer numbers, such as 38 digits fitting into 127 bits. Conversion between BCD and DPD relies on table lookups or operations, implementable in with 2–3 gate delays or in software via simple bit manipulations. Incorporated into the IEEE 754-2008 standard, DPD serves as the densely packed decimal format for the significand in decimal floating-point representations, alongside binary integer decimal (BID) as an alternative. This facilitates precise in systems requiring exact of financial and scientific , avoiding the errors common in binary floating-point. Relative to BCD, DPD offers approximately 20% storage savings and faster digit-wise access, though it introduces minor conversion overhead that is offset by overall efficiency in decimal processing pipelines.

Delegated Path Discovery

Delegated Path Discovery (DPD) is a protocol mechanism in (PKI) that enables a client to delegate the task of locating the certification path for a target to a trusted , rather than performing the independently across multiple certificate authorities. This approach addresses the challenges of complex PKI hierarchies, where clients must otherwise query diverse repositories for intermediate s, certificate lists (CRLs), and other validation data, often leading to inefficiencies in , processing, and time. By centralizing , DPD reduces the computational load on resource-constrained devices, such as mobile endpoints or embedded systems, while maintaining security through server-provided responses that include verifiable certificate chains. The requirements for DPD were formalized in RFC 3379, published in September 2002 by the (IETF), which outlines that a DPD must support a single client request to retrieve all necessary certificates and CRLs for path construction to a specified target certificate. Key functional mandates include the server's ability to return partial paths if full discovery fails, support for certificate policies and constraints, and mechanisms for handling revocation status via CRLs or (OCSP) responses. The distinguishes DPD from Delegated Path Validation (DPV), focusing solely on discovery without performing the validity checks (e.g., signature verification or expiration assessment) that DPV encompasses. Servers must authenticate requests and ensure responses are integrity-protected, typically using (TLS), to prevent unauthorized access or tampering. DPD integrates with broader certificate validation frameworks, such as the Server-based Validation Protocol (SCVP) defined in 5055 (October 2007), which builds on DPD requirements to provide both and validation services over a unified . In practice, DPD enhances in and federated PKIs by minimizing client-side repository lookups, though adoption has been limited compared to full end-entity validation due to reliance on trusted servers and potential single points of failure. Empirical deployments, such as in cloud-based PKI for mobile environments, demonstrate reduced validation times—e.g., from multiple distributed queries to a single server round-trip—but require careful server selection to mitigate risks from misconfigured or compromised delegates. Despite its age, DPD principles remain relevant for optimizing PKI in (IoT) and high-latency networks, where client autonomy is impractical.

Engineering and Technology

Dissipative Particle Dynamics

Dissipative particle dynamics (DPD) is a mesoscale technique that models the dynamics of complex fluids and systems by treating clusters of molecules as coarse-grained particles interacting via pairwise forces in continuous space and discrete time. This approach enables access to spatiotemporal scales larger than those feasible with while incorporating hydrodynamic interactions and absent in continuum methods. DPD was introduced in 1992 by P. J. Hoogerbrugge and J. M. V. A. Koelman at Research to simulate microscopic hydrodynamic phenomena, such as fluid flow, without the lattice artifacts of methods like lattice-gas automata. In 1997, R. D. Groot and P. B. Warren reformulated DPD on a foundation, deriving parameter ranges for stable simulations and establishing its equivalence to a soft-core fluid model with a specified . The method integrates equations of motion using a modified velocity-Verlet algorithm, typically in reduced units where particle mass m = 1, cutoff radius r_c = 1, and k_B T = 1. The dynamics follow \dot{\mathbf{r}}_i = \mathbf{v}_i and \dot{\mathbf{v}}_i = \frac{1}{m_i} \sum_{j \neq i} (\mathbf{F}_C^{ij} + \mathbf{F}_D^{ij} + \mathbf{F}_R^{ij}), where the forces are: conservative \mathbf{F}_C^{ij} = a_{ij} \omega_C(r_{ij}) \mathbf{e}_{ij} for repulsion; dissipative \mathbf{F}_D^{ij} = -\gamma \omega_D(r_{ij}) (\mathbf{e}_{ij} \cdot \mathbf{v}_{ij}) \mathbf{e}_{ij} for friction; and random \mathbf{F}_R^{ij} = \sigma \omega_R(r_{ij}) \theta_{ij} (dt)^{-1/2} \mathbf{e}_{ij} for stochastic noise, with \mathbf{e}_{ij} = (\mathbf{r}_i - \mathbf{r}_j)/r_{ij}, \mathbf{v}_{ij} = \mathbf{v}_i - \mathbf{v}_j, and Gaussian \theta_{ij} of zero mean and unit variance independent for each pair. Weight functions include \omega_C(r) = (1 - r/r_c)^s (often s=1) and \omega_R(r) = (1 - r/r_c)^2 for r < r_c, with \omega_D(r) = [\omega_R(r)]^2 and \sigma^2 = 2 \gamma k_B T enforcing the fluctuation-dissipation theorem. Parameters like conservative amplitude a_{ij} (maximum ~75 for stability), friction \gamma (typically 4.5), and noise \sigma are tuned to match experimental compressibility, viscosity, or diffusion coefficients. DPD excels in capturing mesoscale phenomena like phase separation and self-assembly due to its soft potentials and momentum conservation, yielding hydrodynamic behavior on scales exceeding particle size. Limitations include artificial speed-of-sound reduction from pairwise truncations, requiring large particle numbers (~10^5–10^6) for accurate hydrodynamics, and sensitivity to parameterization for quantitative predictions. Applications encompass polymer solutions for chain conformations and entanglement dynamics, amphiphilic systems forming micelles and vesicles, and biological flows such as red blood cell deformation in Poiseuille flow using models like MS-RBC. It has been extended to multiphase interfaces, colloidal suspensions via fluid particle models, and non-isothermal processes with energy-conserving variants.

Digital Product Definition

Digital Product Definition (DPD) refers to the electronic data elements that specify the three-dimensional computer-aided design (CAD) geometry and associated design requirements for a product, serving as a comprehensive digital representation that supplants traditional two-dimensional engineering drawings in manufacturing and quality assurance processes. This approach embeds geometric dimensioning and tolerancing (GD&T), annotations, and metadata directly within the 3D model, enabling automated validation and reducing interpretation errors across supply chains. DPD facilitates model-based definition (MBD), where the authoritative product information resides in the digital model rather than separate documents, supporting industries such as aerospace and automotive where precision is paramount. Standards like Boeing's D6-51991, revised in April 2019, outline quality assurance requirements for suppliers handling , including data integrity controls, validation procedures, and compliance with practices for embedding product manufacturing information (PMI) in CAD files. establishes schemas for organizing data within 3D models, ensuring interoperability and traceability from design to production; it was developed to address gaps in earlier Y14 standards that focused primarily on 2D drafting. These standards mandate supplier audits to verify that DPD processes prevent data corruption during transfer and maintain fidelity to original design intent, with checklists assessing CAD software validation, access controls, and revision management. In practice, DPD implementation requires certified workflows, such as those audited under for aerospace, to confirm that 3D models include all necessary attributes like material specifications, surface finishes, and assembly instructions without reliance on external files. Benefits include streamlined approvals, as digital approvals replace physical sign-offs, and enhanced downstream applications like simulation and additive manufacturing, though challenges persist in ensuring universal software compatibility and training for legacy systems reliant on 2D outputs. GKN Aerospace's PSI-PUR guidelines, updated July 2024, exemplify supplier mandates for DPD adherence, emphasizing observance of production quality standards to mitigate risks in complex assemblies.

Law Enforcement

Dallas Police Department

The Dallas Police Department (DPD) serves as the principal law enforcement agency for the city of Dallas, Texas, covering a jurisdiction of 385.8 square miles and a population exceeding 1.3 million residents. Established on February 19, 1881, by the , the department initially consisted of a small force focused on basic patrol and response duties amid the city's rapid growth as a frontier trading hub. As of mid-2025, DPD maintains approximately 3,215 sworn officers, supplemented by civilian staff, with ongoing recruitment efforts targeting an increase to 4,000 officers by 2029 to address staffing shortages that have persisted since peaks above 3,800 in the early 2010s. The department operates under Chief Daniel C. Comeaux, appointed in 2024, who oversees strategic priorities including intelligence-driven crime reduction and interagency partnerships. Organizationally, DPD is structured with an executive leadership team including an executive assistant chief for patrol and administrative operations, another for investigations and special operations, and multiple deputy chiefs managing divisions such as intelligence, property crimes, and personnel. Patrol operations are divided into five geographic areas, supported by specialized units for traffic enforcement, , K-9, and community-oriented policing initiatives aimed at reducing violent crime rates, which dropped in categories like homicides from 2016 peaks. The department utilizes advanced tools including body cameras, data analytics for predictive policing, and a public data portal for transparency on arrests and offenses since 2014. DPD's history includes modernization efforts, such as the adoption of motorized patrols in the early 20th century and responses to major events like the 1963 Kennedy assassination investigation, where officers secured evidence and coordinated with federal agencies. A pivotal incident occurred on July 7, 2016, when Micah Johnson ambushed officers during a Black Lives Matter protest, killing five—Brent Thompson, Patrick Zamarripa, Michael Krol, Michael Smith, and Lorne Ahrens—and injuring nine others in a targeted attack motivated by retaliation against police shootings of black suspects. The department has encountered controversies over officer conduct and protest management. In 2020, amid George Floyd-related demonstrations, DPD faced allegations of excessive force, prompting an internal review and the resignation of Chief U. Reneé Hall after city council criticism of response tactics, including less-lethal munitions deployment. Investigations have highlighted lapses in addressing patterns of misconduct, such as repeated complaints against individual officers failing to trigger timely interventions, with eight practices falling short of federal standards per a 2023 analysis. In October 2025, Chief Comeaux unilaterally declined $25 million in ICE funding for immigration enforcement detention support, emphasizing local priorities, a move challenged by Mayor Eric Johnson as bypassing council oversight. Despite challenges, DPD reports sustained declines in force complaints, from higher volumes pre-2015 to 13 in that year, attributed to training reforms and de-escalation protocols implemented post-. Recruitment has improved with incentives like starting salaries over $70,000 and academy expansions, though attrition from retirements and lateral moves remains a factor in maintaining operational capacity.

Denver Police Department

The Denver Police Department (DPD) serves as the primary law enforcement agency for the City and County of Denver, Colorado, handling patrol, investigations, and public safety operations across 155 square miles. Established in 1859 amid the chaos of a gold rush mining camp, the department originated as a small cadre of marshals tasked with enforcing order in a frontier settlement prone to violence and vice. It has since expanded alongside Denver's urbanization, evolving into a modern force with specialized units for major crimes, traffic enforcement, and community engagement. As of mid-2024, the DPD employs approximately 1,546 sworn officers, supported by civilian staff, operating under a budget-aligned target of up to 1,639 personnel to address recruitment challenges post-pandemic. Chief Ron Thomas, appointed in October 2022, leads the department with a stated emphasis on crime prevention, public trust-building, and innovative responses to urban challenges like mental health crises and substance abuse calls. The agency divides Denver into six patrol districts, supplemented by bureaus for investigations, special operations, and intelligence, enabling responses to over 300,000 calls for service annually in a jurisdiction serving around 715,000 residents. The DPD's early history reflected the era's rough justice, with officers often doubling as deputies in a city marked by saloon brawls and claim disputes, leading to informal policing until formal structures emerged by the late 1800s. Professionalization accelerated in the 20th century, incorporating vehicles, radios, and training amid events like the 1960s civil unrest and 1970s drug epidemics, though departmental growth lagged population booms at times. By the 21st century, the force adapted to counterterrorism post-9/11 and implemented body-worn cameras following 2010s policy reviews. Operations emphasize proactive policing, including traffic safety initiatives and partnerships with federal agencies for gang and narcotics enforcement, while recent strategic plans (2023-2027) prioritize data-driven crime reduction and officer wellness to combat staffing shortages. The department has integrated alternatives to traditional responses, such as co-responder programs with mental health professionals for non-violent crises, aiming to reduce officer involvement in welfare checks that constitute a significant call volume. Accountability mechanisms include the Office of the Independent Monitor, established in 2005, and the Citizen Oversight Board, which review complaints and use-of-force incidents, though audits have critiqued transparency gaps in reporting recommendations. The DPD faced federal scrutiny in the 2010s over patterns of excessive force, with the U.S. Department of Justice considering a patterns-or-practices investigation after settlements exceeding $6 million for civil rights claims from 2001-2011; no consent decree resulted, but it prompted internal audits and de-escalation training enhancements. Denver has paid over $40 million in legal settlements related to law enforcement misconduct since 2017, predominantly tied to police actions, fueling demands for stricter protocols. In 2025, Chief Thomas proposed "education-based discipline" to supplement punitive measures, focusing on remedial training for minor infractions to retain officers and foster learning, a shift drawing opposition from oversight advocates concerned it dilutes consequences for misconduct. The city responded by mandating enforceable terms in settlement agreements to ensure compliance, addressing prior lapses where officers evaded reforms post-payouts. Use-of-force policies, revised in 2017, ban chokeholds outright and mandate de-escalation attempts, reflecting broader national trends without admitting systemic bias in departmental data.

Detroit Police Department

The Detroit Police Department (DPD) is the principal law enforcement agency serving the city of , Michigan, covering 139 square miles and approximately 620,000 residents. Established in 1865 through a Michigan state legislative act, it is the largest municipal police force in the state, employing over 2,500 sworn officers as of 2025. The department's jurisdiction is limited to the city limits, focusing on crime prevention, investigation, and public safety through data-driven strategies emphasizing patrol, specialized units, and community partnerships. Under Chief Todd Bettison, appointed permanently on February 18, 2025, following his interim role after James E. White's tenure, the operates with a fiscal year 2026 budget of $455.4 million, primarily allocated to personnel costs representing 92.3% of expenditures. Recent performance metrics indicate substantial declines in violent crime: through September 30, 2025, homicides totaled 132, a 15% reduction from 155 in the same period of 2024; nonfatal shootings dropped correspondingly; and carjackings fell by 30%, surpassing 60-year historical lows and attributed to enhanced staffing and targeted enforcement. Historically, the DPD has faced persistent challenges with internal corruption and excessive use of force, prompting federal intervention. In 2003, following a U.S. Department of Justice investigation into patterns of unconstitutional practices—including unwarranted arrests, detainee abuse, and deadly force incidents—the department entered consent decrees mandating reforms in training, accountability, and oversight. These agreements, enforced until 2016, required systemic changes such as improved use-of-force policies and independent monitoring, resolving after documented compliance. Corruption scandals have recurred, with federal probes uncovering officer misconduct. In 2021–2023, investigations by the FBI's Public Corruption Task Force led to convictions including a former lieutenant in the department's Integrity Unit sentenced to 2.5 years for bribery and evidence tampering tied to protecting criminal enterprises. Additional cases involved detectives accepting bribes from towing companies and drug traffickers, as well as systemic issues in units like Major Violators, where officers allegedly stole narcotics and cash from evidence, per a 2021 internal report. These incidents, often linked to economic pressures in high-crime environments, have driven ongoing internal affairs reforms, though federal indictments of at least 17 officers in prior decades highlight enduring vulnerabilities in oversight. Organizationally, the DPD is structured into precincts, specialized bureaus (e.g., homicide, narcotics, emergency services), and support units like aviation and K-9, overseen by a Board of Police Commissioners established in 1974 for civilian accountability. Post-consent decree, emphasis has shifted to de-escalation training and community-oriented policing, contributing to crime reductions amid Detroit's demographic and economic recovery efforts. Despite progress, critics from civil rights groups argue residual patterns of over-policing in minority neighborhoods persist, though DOJ closure affirmed substantial compliance.

Mental Disorders

Dependent Personality Disorder

Dependent Personality Disorder (DPD) is classified as a Cluster C personality disorder in the DSM-5, marked by a pervasive pattern of excessive psychological dependence on others, beginning by early adulthood and present across various contexts. Individuals with DPD exhibit submissive and clinging behaviors driven by an intense fear of separation and an unrealistic preoccupation with being unable to care for themselves independently. This disorder differs from normal dependency by its maladaptive intensity, leading to significant distress or impairment in social, occupational, or other functioning, and is not attributable solely to cultural norms or another mental condition. The core features involve difficulty initiating or sustaining independent actions, urgent seeking of replacement relationships upon loss of a caregiver, and discomfort when alone due to fears of self-care inability. Unlike adaptive attachment, DPD reflects exaggerated helplessness that prioritizes external validation over self-efficacy, often resulting in tolerance of abusive dynamics to avoid abandonment. Diagnosis requires at least five of the following DSM-5 criteria: (1) difficulty making everyday decisions without excessive reassurance from others; (2) needing others to assume responsibility for major life areas; (3) difficulty expressing disagreement due to fear of disapproval or abandonment; (4) reluctance to initiate projects independently owing to low self-confidence in abilities rather than lack of energy; (5) extreme efforts to secure support, including undertaking unpleasant tasks; (6) discomfort or helplessness when alone from fears of inability to self-care; (7) immediate pursuit of new relationships for care upon ending a prior one; and (8) preoccupation with fears of self-responsibility. These must cause clinically significant impairment, not occur exclusively during major depressive episodes or developmental stages, and not be better explained by another disorder like . Epidemiological data indicate a lifetime prevalence of approximately 0.5% in the U.S. adult population, based on the 2015 , with rates around 0.49% to 0.6% across studies. Prevalence appears similar between males and females, though some estimates suggest slight female predominance; it is higher in younger adults (0.9% in ages 18-29) and declines with age. Comorbidity is common with other like avoidant or obsessive-compulsive personality disorders, as well as anxiety and depressive conditions. Etiology involves a multifactorial interplay of genetic vulnerabilities, temperamental factors, and environmental influences, with no single causal pathway identified. Biologic elements include heritability linked to anxiety proneness and genetic markers for neuroticism, modulated by epigenetic changes from early life experiences such as overprotective parenting, chronic illness in childhood, or separation trauma that reinforces learned helplessness. Adverse events like emotional or physical abuse increase risk by fostering beliefs in personal incompetence, while cultural emphases on interdependence may exacerbate but not originate the disorder. Developmental models emphasize insecure attachment styles, where repeated reinforcement of dependency over autonomy shapes maladaptive traits, though prospective longitudinal evidence remains limited. Treatment primarily relies on psychotherapy, as no medications are specifically approved for DPD core symptoms, and pharmacotherapy evidence is sparse, typically targeting comorbidities like anxiety or depression with SSRIs or anxiolytics on a symptomatic basis. (CBT) shows promise in challenging distorted beliefs of helplessness and building self-reliance skills, though controlled trials for DPD specifically are few; broader CBT efficacy for personality disorders supports symptom reduction and functional improvement. Psychodynamic approaches address underlying fears of abandonment and foster autonomy through exploration of relational patterns, with case series indicating benefits but lacking large-scale RCTs. Prognosis varies, with early intervention improving outcomes, but chronicity and resistance to independence often necessitate long-term therapy; group settings may aid by reducing isolation but require careful management to prevent exploitation of submissive tendencies. Overall, empirical support for interventions is weaker than for other personality disorders, highlighting the need for further research.

Depersonalization-Derealization Disorder

Depersonalization-derealization disorder (DPDR) is a dissociative disorder characterized by persistent or recurrent experiences of depersonalization (feeling detached from one's own body, thoughts, or feelings, as if observing oneself from outside), derealization (perceiving the external world as unreal, dreamlike, or distorted), or both, with intact reality testing. According to DSM-5 criteria, these experiences must cause significant distress or impairment in social, occupational, or other functioning; not be attributable to substances, medical conditions, or other mental disorders; and persist despite awareness that the detachment is unreal. Symptoms include emotional numbing, distorted body image, a sense of being robotic or automated, and perceptual alterations such as visual distortions or heightened emotional detachment, often leading to anxiety about losing control or "going crazy." Episodes can be triggered by stress and vary in duration from minutes to years, with chronic cases more common in clinical settings. Epidemiological data indicate a lifetime prevalence of approximately 1-2% in the general population, though transient episodes occur in 25-75% of individuals at some point. Rates are higher among and young adults, with clinical samples showing 5-20% in outpatients and up to 41.9% in inpatients; comorbidities include (up to 60% in depression samples) and (30% in veterans). Etiological factors primarily involve severe psychosocial stress, particularly childhood emotional abuse, neglect, or trauma, which may disrupt self-referential processing and emotional regulation as an adaptive detachment response. Neurobiological models suggest involvement of prefrontal-limbic dysregulation, but exact mechanisms remain unclear, with no single genetic or environmental cause identified; substance use or acute panic can precipitate but not solely cause chronic . Evidence-based treatment focuses on psychotherapy, particularly (CBT), which targets symptom monitoring, grounding techniques, and challenging detachment beliefs, showing moderate efficacy in reducing severity. No pharmacotherapies are specifically approved, though selective serotonin reuptake inhibitors or anxiolytics may alleviate comorbid symptoms; pharmacotherapy trials, including , have yielded inconsistent results. Mindfulness and grounding exercises can mitigate acute episodes, but long-term outcomes depend on addressing underlying trauma.

Chemistry

Dihydropyrimidine Dehydrogenase

Dihydropyrimidine dehydrogenase (DPD), encoded by the DPYD gene on chromosome 1p21.3, is the rate-limiting enzyme in the catabolic pathway of endogenous pyrimidines such as uracil and thymine. It catalyzes the NADPH-dependent reduction of these bases to their 5,6-dihydro derivatives—specifically, uracil to 5,6-dihydrouracil and thymine to 5,6-dihydrothymine—as the initial step in their degradation. This process prevents accumulation of pyrimidines, which can otherwise lead to metabolic imbalances, and DPD also metabolizes exogenous compounds like the chemotherapeutic agent (5-FU), converting it primarily to 5,6-dihydro-5-fluorouracil. The enzyme's activity accounts for approximately 70-80% of 5-FU clearance in the liver, where it is predominantly expressed. Structurally, DPD is a homotetrameric flavoprotein with a molecular weight of about 110 kDa per subunit, containing flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) as prosthetic groups, along with iron-sulfur clusters essential for electron transfer. The DPYD gene spans over 1 Mb and comprises 23 exons, with expression regulated in a tissue-specific manner, highest in liver, gastrointestinal tract, and mononuclear cells. Over 100 genetic variants have been identified in DPYD, many of which impair enzyme function through missense mutations, splice-site alterations, or deletions; notable examples include c.1905+1G>A (DPYD2A), associated with complete or near-complete deficiency, and c.2846A>T (DPYD13), linked to partial activity reduction. Partial DPD deficiency occurs in 3-5% of the general , with complete deficiency rarer at about 0.2-0.7%, varying by —higher variant frequencies in Europeans for certain alleles like DPYD2A (prevalence ~1-2%) compared to non-Europeans. Clinically, DPD deficiency manifests as an autosomal recessive pharmacogenetic , often asymptomatic in the absence of analogs but causing severe, potentially fatal upon 5-FU or administration, including grade 3-4 adverse events like myelosuppression, , and in up to 20-30% of deficient patients receiving standard doses. Neurological symptoms in congenital cases include developmental delay, seizures, and due to accumulation, though many carriers remain undetected without drug challenge. Guidelines from bodies like the Clinical Pharmacogenetics Implementation Consortium recommend pre-treatment DPYD for at-risk variants, with dose reductions of 25-50% or alternative therapies for carriers to mitigate risks, supported by evidence of reduced incidence. Ethnic in variant prevalence underscores the need for population-specific screening, as non-European cohorts show lower rates of canonical European alleles but potentially underrecognized novel variants.

Politics and Government

Development Plan Document

A Development Plan Document (DPD) is a statutory document forming part of the Local Plan prepared by local planning authorities in to guide the spatial development and use of land within their areas. DPDs outline policies, strategies, and site allocations that address local needs for housing, employment, infrastructure, and environmental protection, ensuring decisions on planning applications align with a coherent vision for sustainable growth. They replaced unitary development plans and structure plans under the Planning and Compulsory Purchase Act 2004, integrating with the National Planning Policy Framework (NPPF) to promote economic, social, and environmental objectives. DPDs must undergo rigorous preparation processes, including , appraisals to assess environmental impacts, and an examination by a government-appointed to verify —defined as being positively prepared, justified, effective, and consistent with national policy. Once adopted, DPDs carry significant weight in planning decisions, superseding less formal supplementary planning documents. Common types include the Core Strategy DPD, which establishes overarching principles; Site Allocations DPDs, identifying specific land for ; and Area Action Plans for targeted regeneration zones. Local authorities monitor DPD implementation annually, reporting progress under Regulation 34 of the Town and Country Planning (Local Planning) (England) Regulations 2012, with updates required every five years to reflect changing circumstances like targets or goals. The framework emphasizes community involvement from early stages, with statutory consultation periods allowing representations that can influence revisions before submission for examination. Critics, including some associations, note challenges in timely production due to resource constraints and legal challenges, though reforms in the Levelling-up and Regeneration Act 2023 aim to streamline processes by replacing Local Development Schemes with more flexible timelines. As of 2024, over 90% of English local authorities have adopted Local Plans incorporating DPDs, though coverage varies, with urban areas often facing delays from competing land-use demands. DPDs thus serve as enforceable tools for balancing pressures against constraints like protections and flood risks, grounded in evidence-based assessments rather than aspirational statements.

Democratic Party of Djibouti

The of Djibouti (French: Parti Démocratique Djiboutien, PDD), also referred to as PDD/PADD, is a minor opposition political party in , operating within a political system dominated by President Ismaïl Omar Guelleh's (RPP) since the country's was introduced in 1992. The party advocates for democratic reforms, greater political , and alternation of power, positioning itself against the ruling regime's authoritarian practices, including restrictions on opposition activities and electoral irregularities. Led by Mohamed Daoud Chehem, an ethnic Afar politician and former civil servant, the PDD has maintained a low parliamentary presence but has faced repeated government crackdowns, including arrests of its leaders during protests. Founded in the early amid the expansion of legalized opposition parties following Djibouti's 1992 constitutional reforms, the PDD emerged as part of efforts to challenge the RPP's monopoly on power, which has controlled all national elections since in 1977. Chehem, the party's longstanding , ran as a presidential candidate in the , where he received minimal support—approximately 0.2% of the vote—in a contest widely criticized for lacking fairness due to opposition boycotts and dominance. The party's activities often align with broader opposition coalitions, such as the Union for Democratic Change (UAD) and the Union for Democracy and Justice (UDJ), reflecting its strategy to amplify limited resources against the ruling Union for the Presidential Majority (UMP). In parliamentary elections, the PDD has achieved modest gains through alliances. In the 2018 legislative vote, the UDJ-PDD secured 7 seats in the 65-member , representing the primary opposition bloc amid a ruling coalition sweep of the remaining seats; the election was marred by low turnout and reports of intimidation. By contrast, the party did not gain seats in the February 2023 parliamentary election, where most opposition groups boycotted over concerns of fraud and exclusion, allowing the UMP to claim 58 seats. These outcomes underscore the PDD's constrained influence in a system rated as "not free" by observers, with scoring 7/100 in political rights and as of 2024, citing systemic barriers like arbitrary detentions and judicial bias against dissenters. The PDD's operations have been hampered by government repression, exemplified by the arrests of Chehem and other leaders following post-election protests that resulted in two deaths and clashes with security forces. Such incidents highlight the party's role in mobilizing against perceived electoral manipulation and one-party dominance, though its impact remains limited by state control over media, funding, and electoral commissions. Despite these challenges, the PDD continues to participate in selective electoral processes and dialogues, as seen in Guelleh's 2019 consultations with opposition figures, though these yielded no substantive reforms. The party's reflects broader Afar grievances in a country where the Issa-dominated regime has maintained power through alliances with former rebels like the Front for the Restoration of Unity and Democracy (FRUD).

Business and Logistics

DPDgroup

DPDgroup was an international parcel delivery network headquartered in , , specializing in express B2B and B2C parcel services across and beyond. It operated under , a wholly owned of La Poste Groupe, the French owned by the French and Caisse des Dépôts. The company rebranded to in March 2023 to emphasize its geographical expansion and global ambitions, while retaining core brands such as DPD, Chronopost, and SEUR for regional operations. Originally founded as Deutscher Paketdienst (DPD) in 1976 by a consortium of 18 German freight forwarders, the company focused initially on domestic parcel services in Germany before expanding internationally through acquisitions. In 2001, GeoPost acquired a majority stake, integrating DPD into its network and accelerating growth into markets like Benelux, Switzerland, and Spain during the 2000s. By the 2010s, DPDgroup had established a dense European road network supporting over 500 daily cross-border operations across 35 countries, with further extensions into Asia, Africa, and the Americas. In 2023, under the GeoPost branding, the company reported revenues of €15.69 billion, a 0.7% increase from 2022 despite market challenges, while handling approximately 2.1 billion parcels annually through a network of over 108,000 pickup points and delivering 8 million parcels daily. It employed around 57,000 people globally, prioritizing sustainable practices such as zero- and low-emission deliveries in major European cities by 2025. Operations emphasized innovative solutions like automated sorting and last-mile efficiency, though the firm has faced criticism for delivery delays and driver working conditions in customer reviews and media reports.

Other Uses

Deoxypyridinoline

Deoxypyridinoline (DPD), also denoted as D-pyridinoline or D-Pyr, is a mature, non-reducible formed between residues in , predominantly within . This trivalent structure arises during the extracellular maturation of , where it covalently links three polypeptide chains to enhance the tensile strength and rigidity of the . Unlike reducible cross-links, DPD resists enzymatic breakdown and accumulates in mature , with concentrations approximately tenfold higher than its analog pyridinoline (PYD) in skeletal . During osteoclast-mediated , collagen fibrils are degraded, releasing DPD into the circulation; the molecule is neither significantly reutilized by the body nor derived from dietary sources in appreciable amounts, leading to its quantitative primarily in . This property positions free DPD as a direct, bone-specific of breakdown and overall bone turnover rate, outperforming less specific markers like , which can be influenced by diet or non-skeletal sources. levels exist but are lower and less commonly assayed due to partial binding to proteins; urinary DPD, normalized to (e.g., nmol/mmol ), is preferred for its sensitivity to acute changes in resorption. Analytical methods include (HPLC) for total DPD or immunoassays for free fractions, with reference intervals varying by age, sex, and menopausal status—typically 2.3–5.1 nmol/mmol in premenopausal women and elevated postmenopause. Clinically, elevated urinary DPD levels signal increased in conditions such as postmenopausal , Paget's disease, or , aiding in , fracture risk assessment, and monitoring of antiresorptive therapies like bisphosphonates or . For instance, successful treatment reduces DPD excretion, correlating with preserved bone mineral density. In pediatric populations, DPD tracks growth-related turnover, while in metabolic disorders like , it may reveal despite normal density scans. Limitations include diurnal variability (peaking nocturnally) and influences from renal function or , necessitating standardized collection (e.g., second-void ) and integration with formation markers like for comprehensive turnover evaluation. Despite its specificity, DPD's utility is enhanced when combined with imaging, as isolated elevations do not distinguish pathological from physiological resorption without context.