<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31410072</termId><termName>schlieren photography</termName><termType>PT</termType><termNote><![CDATA[ Quasi-photographic techniques to record different densities in a gas as a pattern of colored bands of light and dark; frequently used to record patterns of radiated heat; not all forms of this technique require a camera and lens. ]]></termNote><termCreatedDate>2026-03-30 20:50:15</termCreatedDate><relation><relationType>UF</relationType><termId>31410073</termId><termName>photography, schlieren</termName><termType>ND</termType></relation><relation><relationType>BT</relationType><termId>31371272</termId><termName>picture-taking techniques by radiation type</termName><termType>PT</termType></relation></term>  </Zthes>