All articles starting with S

Secondary Chorea

Secondary chorea (ICD-11 8A01.1) is involuntary choreiform movement caused by acquired conditions, infections, drugs, metabolic, autoimmune, vascular, or paraneoplastic disorders, unlike genetic primary chorea; treatment targets the underlying cause.

Secondary color

Secondary color: a color made by mixing two primaries in a color system. RGB secondaries are yellow, cyan, magenta; CMY secondaries are blue, red, green; RYB gives orange, green, purple.

Secondary crest myofibroblast

Secondary crest myofibroblast (SCMF, alveolar myofibroblast, CL:4033016): a transient PDGFRα/αSMA-positive lung mesenchymal cell at secondary septa tips that contracts crests, produces elastin, and drives alveologenesis; its failure links to BPD and COPD.

Sep 29, 2026

Secondary cytoreductive surgery

Secondary cytoreductive surgery (SCRS) is an operation to remove recurrent ovarian cancer tumors after a first course of treatment, benefiting platinum-sensitive, limited-volume disease when complete resection is achieved.

Secondary data

Secondary data is data collected by a party other than the researcher who later analyzes it, including census data, government administrative records, geospatial data, and datasets archived from earlier studies.

Sep 29, 2026

Secondary data analysis

Secondary data analysis is research that reanalyzes data already collected by others, such as surveys, administrative records, or electronic health records, to answer questions the original collection did not address.

Secondary dystonia

Secondary dystonia (ICD-11 8A02.1) is dystonia caused by another condition or external factor such as drugs, stroke, trauma, hypoxia, toxins, or heredodegenerative disease, distinguished from primary dystonia by rest-onset movements, hemidystonia, and other neurological signs.

Secondary eczema

Secondary eczema (id reaction, autoeczematisation, autosensitisation dermatitis; ICD-11 EA88.2/EA88.3) is eczematous dermatitis arising secondary to another skin disease, typically a widespread itchy eruption following a neglected lower-leg rash, infection, or contact dermatitis.

Secondary education

Secondary education, the schooling stage between primary and tertiary education, comprises ISCED lower secondary (level 2) and upper secondary (level 3). Global upper secondary completion rose from 37% in 2000 to 61% in 2024, versus 29% in Sub-Saharan Africa.

Secondary education in Brunei

Secondary education in Brunei Darussalam (SPN21): two-year lower secondary common curriculum, then General, Applied, or BTEC programmes ending in Brunei-Cambridge GCE O Level and IGCSE.

Secondary education in Fiji

Secondary education in Fiji covers Years 9 to 13 for ages 14 to 18 and is compulsory to Year 12, with free tuition and national examinations including the FY13CE for university entry.

Secondary education in France

Secondary education in France: the collège (6e to 3e, ending in the brevet) and the lycée (seconde to terminale, ending in the baccalauréat), covering structure, 2026 exam reforms, spending, PISA decline, and recent measures.

Secondary education in Japan

Secondary education in Japan is the 3+3 system of compulsory lower secondary school (chugakko, ages 12-15) and upper secondary school (kotogakko) under the 1947 6-3-3-4 structure, with entrance exams, general/specialized/integrated courses, and FY2026 tuition-free support.

Secondary education in Samoa and Tonga

Secondary education in Samoa and Tonga is delivered through small national systems in which mission-founded colleges and government schools carry most of each country's secondary schooling.

Secondary education in Scotland

Secondary education in Scotland covers S1-S6, with the Senior Phase (S4-S6) taking National Qualifications under Curriculum for Excellence. Reforms since 2021 replace the SQA with Qualifications Scotland and reduce exam reliance.

Secondary education in the Anglophone Caribbean

Secondary education in the Anglophone Caribbean is the post-primary system of the English-speaking Commonwealth Caribbean, retaining British grammar-school traditions, 11-plus-style selection, and regionally administered CSEC and CAPE examinations.

Secondary education in the United States

Secondary education in the United States covers grades 9-12, ending in the high school diploma. State- and locally governed, it underwent the uniquely American high school movement (1910-1940) and lacks dedicated upper-secondary vocational tracks.

Secondary effect of trauma

Secondary effect of trauma (ICD-11 code ND57) is a residual injury category covering deformity NOS, old amputation, and scarring from previous injury, excluding PTSD and post-traumatic wound infection.

Oct 15, 2026

Secondary electron emission

Secondary electron emission is the release of electrons from a solid struck by energetic particles, discovered in 1902 and quantified by the secondary emission yield δ.

Sep 29, 2026

Secondary electrospray ionization

Secondary electrospray ionization (SESI) is an ambient mass spectrometry technique in which an electrospray ionizes vapors in a gas stream, enabling real-time analysis without sample preparation.

Secondary erythromelalgia

Secondary erythromelalgia (secondary erythermalgia) is burning pain, redness, and heat of the extremities caused by an underlying disorder, most often myeloproliferative disease, autoimmune conditions, infections, or drugs, relieved by cooling and often responsive to aspirin in blood disorders.

Secondary fatty amines

Secondary fatty amines are organic compounds in which one or two long-chain fatty alkyl groups, typically C8 to C22, are bonded to a nitrogen atom that retains one hydrogen.

Secondary female infertility

Secondary female infertility (ICD-11 GA31.1) is infertility in a woman with at least one prior confirmed clinical pregnancy. Causes include tubal damage, ovulation disorders, endometriosis, fibroids, and prior pregnancy or surgical complications; it affects about 11% of US couples.

Oct 15, 2026

Secondary flow

Secondary flow is the component of fluid motion perpendicular to a flow's main direction, usually vortical circulation driven by curvature, as in curved pipes and river bends.

Secondary gout

Secondary gout, also called secondary hyperuricemia-related gout, is gout arising during another disease or from drugs, via purine overproduction, nucleic acid turnover, or reduced renal urate clearance; ICD-11 codes FA25.1 include lead- and drug-induced forms.

Secondary growth

Secondary growth: lateral thickening of stems and roots by the vascular cambium and cork cambium, producing wood and periderm in gymnosperms and dicots; rare in monocots, which use a distinct monocot cambium in only about 22 genera.

Secondary haemophagocytic lymphohistiocytosis

Secondary haemophagocytic lymphohistiocytosis (sHLH, secondary HLH): a life-threatening hyperinflammatory syndrome triggered by infection, malignancy, autoimmune disease, or drugs, diagnosed with HLH-2004 criteria or HScore and treated with trigger-directed immunosuppression.

Secondary headache

Secondary headache (ICD-11 8A84) is headache attributed to another causative disorder, spanning ICHD-3 categories 5-12 (trauma, vascular, infection, substances, and others). Distinguished from primary headache by red flags such as thunderclap onset, papilledema, and fever.

Secondary hyperaldosteronism

Secondary hyperaldosteronism (secondary aldosteronism): excess adrenal aldosterone driven by extra-adrenal RAAS activation from reduced renal blood flow, with high renin and aldosterone; causes include renal artery stenosis, heart failure, cirrhosis, nephrotic syndrome; treated by correcting the cause.