On-demand self-service lets a consumer provision a computing capability when needed without requiring a human interaction with the provider for each request. The consumer might request server time or network storage through a portal or application programming interface.^[ref]

For example, an authorized research workflow can request a temporary machine, run an analysis and release it through automated calls. The provider can still enforce quotas, permitted configurations and account policy. Self-service describes how a request is fulfilled; it does not promise unlimited capacity or remove the need for authorization. Automating repeated provisioning makes temporary resources practical while leaving lifecycle and data-retention choices explicit.

Broad network access means cloud capabilities are reachable over a network through standard mechanisms usable by different kinds of client platforms. NIST lists phones, tablets, laptops and workstations as examples.^[ref]

For example, a browser interface and an application programming interface can expose the same service to interactive users and automated analyses. Network accessibility does not imply public authorization: a private cloud can restrict authenticated clients while still using broadly supported network interfaces. Latency, bandwidth and intermittent connectivity affect how an application should divide work between client and service; an accessible remote operation is not equivalent to a local memory access.

Resource pooling combines provider computing resources to serve multiple consumers, with physical and virtual resources assigned and reassigned according to demand. NIST emphasizes multi-tenant service and some location independence: consumers generally select an abstraction or broad location requirement rather than one permanently assigned physical server.^[ref]

Pooling can improve utilization when consumers' peak demands occur at different times. It also requires isolation and allocation controls so that one consumer cannot read another's data or monopolize all capacity. For example, virtual machines may share a physical host while retaining separate address spaces. The resource pool and the mechanism enforcing its boundaries are distinct design responsibilities.

Rapid elasticity is the ability to provision and release computing capacity quickly in response to demand, often automatically. The consumer may experience capacity as readily available even though the provider operates finite physical resources.^[ref]

For example, a service can add workers when its queue grows and remove them after the backlog clears. A control rule needs an observation signal, a scaling policy and time for new workers to become ready. Elastic capacity does not make every program parallel: a serial bottleneck, shared database or slow startup can prevent additional workers from increasing throughput. Releasing capacity also requires preserving needed state outside workers that may disappear.

Measured service is the cloud-computing characteristic in which resource use is monitored, controlled and reported through metering appropriate to the service. Examples include processor-hours, stored bytes, network transfer and active accounts. Metering makes usage visible to the provider and consumer; it does not require one universal billing formula.^[ref]

For example, a batch of simulations can record the number of machine-hours consumed independently of the number of simulations completed. A failed run may still consume resources. Selecting a meaningful unit therefore requires distinguishing allocated capacity, elapsed use and delivered work. These measurements support accounting and capacity decisions without by themselves measuring the scientific value or correctness of the results.

Primary source: www.nxp.com.cn/docs/en/application-note/AN4327.pdf

Verified locator: Freescale Semiconductor application note AN4327, Rev. 2, November 2012, by Santiago Lopez (cover). Sections 2.2 and 3.1.2 describe the red/infrared channels, AC/DC separation and multiplexing. The introductory wording conflates saturation with dissolved oxygen; use the note for its described optical implementation, not that physiological wording.

Primary source: www.fda.gov/regulatory-information/search-fda-guidance-documents/pulse-oximeters-premarket-notification-submissions-510ks-guidance-industry-and-food-and-drug

Verified locator: FDA technical guidance issued 4 March 2013. Full published title includes Pulse Oximeters - Premarket Notification Submissions [510(k)s]: Guidance for Industry and Food and Drug Administration Staff. Clinical Performance, SpO2 Accuracy, recommends comparing paired readings to simultaneous co-oximetry of arterial samples under controlled inspired-oxygen mixtures and reporting root mean square difference. Source is cited for technical validation methodology, not asserted to be the latest regulatory policy.

Primary source: www.aarc.org/wp-content/uploads/2025/03/davis-et-al-2013-aarc-clinical-practice-guideline-blood-gas-analysis-and-hemoximetry-2013.pdf

Verified locator: Respiratory Care 58(10), 1694–1703, October 2013. Original p. 1694 prints Michael D. Davis, Brian K. Walsh, Steve E. Sittig and Ruben D. Restrepo. Section 1.0 distinguishes measured gas tensions/pH from derived bicarbonate. Sections 4.6 and 6.1.2–6.1.9 specify sampling documentation, contamination/delay and calculated-saturation/temperature limitations.

Primary consensus publication, JAMA 307(23), 2526–2533 (2012), DOI 10.1001/jama.2012.5669. The abstract and definition assess oxygenation alongside other syndrome criteria.

National Library of Medicine test description, updated 26 June 2025. Sections “What is an arterial blood gas test?” and “Is there anything else I need to know?” distinguish oxygen partial pressure, saturation and a pulse-oximeter estimate. The earlier blood-oxygen-level page redirects to this canonical URL.

Official National Heart, Lung, and Blood Institute explanation, What Is Acute Respiratory Distress Syndrome?, updated 24 March 2022. The main explanatory paragraphs describe fluid accumulation within alveoli, impaired oxygen transfer, altered surfactant function and loss of normal lung mechanics. Used for the syndrome description; the historical ventilation trial is cited through its separate primary source card.

Primary source: www.abim.org/certification/policies/internal-medicine-subspecialty-policies/pulmonary-disease/

Verified locator: Primary institutional Pulmonary Disease section of Internal Medicine and Subspecialty Policies. Training and Procedure Requirements lists supervision and interpretation of pulmonary-function testing, bronchoscopy and ventilator-related competencies.

Official National Heart, Lung, and Blood Institute account. The section Dilated cardiomyopathy describes enlargement and weakening of the ventricles and impaired pumping. Used for the disease description; original numerical volume examples in the article are not diagnostic thresholds.

Primary source: ifcardio.org/pdf/italian-heart-journal/2000/07/20000012.pdf

Verified locator: Italian Heart Journal 1(7), 457–463, July 2000. Original full PDF: p. 457 full first byline Ruggero De Paulis and nine-case report; p. 458 Methods explicitly attributes design to RDP and describes the two corrugation orientations, Figures 1–4. Abstract and Results describe visual inspection, transesophageal echocardiography and angiography. PubMed record PMID 10933327 corroborates the publication.

Primary source: unicamillus.org/en/lecturers/ruggero-de-paulis/

Verified locator: Named primary faculty page, Heart Surgery heading and biography crediting the Valsalva prosthesis; named profile links portrait unicamillus.org/wp-content/uploads/docenti/foto/de-paulis.png?x35256= . Used for professional identification, not to infer unreported dates or clinical efficacy.

Primary source: www.ghcspa.com/europeanhospital/medici/salica-andrea

Verified locator: Named primary institutional physician page headed Salica Andrea, specialty Cardiochirurgo, with linked portrait www.ghcspa.com/sites/default/files/2024-08/salica.jpg . Full name independently present in the 2019 joint paper. No inferred birth date, middle name or individual coauthor role.

National Library of Medicine, MedlinePlus Medical Encyclopedia, Palpation, Information section; reviewed 1 January 2025. Originating health-information entry defines examination with fingers or hands and lists size, consistency, texture, location and tenderness as observed attributes. No diagnostic accuracy estimate follows from that definition.

Primary source: www.cancer.gov/publications/dictionaries/cancer-terms/def/cardiologist

Verified locator: Official National Cancer Institute dictionary entry defining specialized training in diagnosing and treating heart and blood-vessel disease.

Manufacturer description of its ABL90 FLEX PLUS analyzer. The Confidence in results subsection states that co-oximetry parameters are measured by direct optical spectrophotometry. This locator concerns the measurement method; product performance claims and clinical advice are not used here.

National Heart, Lung, and Blood Institute, Heart Tests, Coronary angiography subsection. The originating institutional description explains contrast dye, usually containing iodine, and X-ray imaging of coronary arteries. The Cardiac CT scan subsection separately describes acquisition of many X-ray views and reconstruction of a three-dimensional model.