Exploring the possible relationship between ambient heat and sudden infant death with data from Vienna, Austria

A non-linear relationship between maximum ambient temperature and number of sudden infant death syndrome (SIDS) cases had been reported for Montreal, Canada, for the warm season. In particular, high maximum ambient temperatures were found to be extra-hazardous for infants. The study was replicated w...

Ausführliche Beschreibung

Gespeichert in:
Bibliographische Detailangaben
Veröffentlicht in:PloS one 2017-09, Vol.12 (9), p.e0184312-e0184312
Hauptverfasser: Waldhoer, Thomas, Heinzl, Harald
Format: Artikel
Sprache:eng
Schlagworte:
Online-Zugang:Volltext
Tags: Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
container_end_page e0184312
container_issue 9
container_start_page e0184312
container_title PloS one
container_volume 12
creator Waldhoer, Thomas
Heinzl, Harald
description A non-linear relationship between maximum ambient temperature and number of sudden infant death syndrome (SIDS) cases had been reported for Montreal, Canada, for the warm season. In particular, high maximum ambient temperatures were found to be extra-hazardous for infants. The study was replicated with data from Vienna, Austria, applying the same statistical approach. Vienna is roughly comparable to Montreal with regard to temperatures in the warm season, size of population, and number of SIDS cases. Although the Viennese study was powerful enough to detect even smaller effects, the Montrealean results could not be confirmed. The Viennese results do not support the hypothesis of a strong effect of maximum ambient temperature on the risk of SIDS during the warm season.
doi_str_mv 10.1371/journal.pone.0184312
format Article
fullrecord <record><control><sourceid>gale_plos_</sourceid><recordid>TN_cdi_plos_journals_1936206955</recordid><sourceformat>XML</sourceformat><sourcesystem>PC</sourcesystem><galeid>A503586563</galeid><doaj_id>oai_doaj_org_article_76e3f71ecd6b49a595c121c604a674fb</doaj_id><sourcerecordid>A503586563</sourcerecordid><originalsourceid>FETCH-LOGICAL-c692t-8652a9dc3f9c7a3c7de5b50efaef893ea1d3dc909a4cff62f07c79d23ac613923</originalsourceid><addsrcrecordid>eNqNk22L1DAQx4so3nn6DUQLgii4a5s0afNGWI5TFw4OfLi3YZqHbZZusyapd357Zx_u2JV7IYU2TH_zT-afmSx7WRbTktblx6UfwwD9dO0HMy3KpqIleZSdloKSCScFfXywPsmexbgsCkYbzp9mJ6Rp6pqQ5jTzF7fr3gc3LPLUmXztY3Rtb_JgekjOD7Fz67w16caYIYdV68yQ8s5AymHQeRy1xrgbLGBYY7jLbxy-NCTIbfCr_BozBviQz8aYgoPn2RMLfTQv9t-z7Ofnix_nXyeXV1_m57PLieKCpEnDGQGhFbVC1UBVrQ1rWWEsGNsIaqDUVCtRCKiUtZzYola10ISC4iUVhJ5lr3e6WF2Ue6-iREfQDy4YQ2K-I7SHpVwHt4LwR3pwchvwYSEhJKd6I2tuqK1LozRvKwFMMFWSUvGiAl5XtkWtT_vdxnZltEKTAvRHosd_BtfJhf8tGWtqwgQKvNsLBP9rNDHJlYvK9D0Mxo-7c-PB2RZ98w_6cHV7agFYAF6Qx33VRlTOWEEZGswpUtMHKHy0WTmFjWUdxo8S3h8lIJPMbVrAGKOcf__2_-zV9TH79oDF_upTF30_blvwGKx2oArYqsHYe5PLQm7m4s4NuZkLuZ8LTHt1eEH3SXeDQP8CaoMJrw</addsrcrecordid><sourcetype>Open Website</sourcetype><iscdi>true</iscdi><recordtype>article</recordtype><pqid>1936206955</pqid></control><display><type>article</type><title>Exploring the possible relationship between ambient heat and sudden infant death with data from Vienna, Austria</title><source>MEDLINE</source><source>DOAJ Directory of Open Access Journals</source><source>Public Library of Science</source><source>PubMed Central</source><source>Free Full-Text Journals in Chemistry</source><source>EZB Electronic Journals Library</source><creator>Waldhoer, Thomas ; Heinzl, Harald</creator><contributor>Räisänen, Sari Helena</contributor><creatorcontrib>Waldhoer, Thomas ; Heinzl, Harald ; Räisänen, Sari Helena</creatorcontrib><description>A non-linear relationship between maximum ambient temperature and number of sudden infant death syndrome (SIDS) cases had been reported for Montreal, Canada, for the warm season. In particular, high maximum ambient temperatures were found to be extra-hazardous for infants. The study was replicated with data from Vienna, Austria, applying the same statistical approach. Vienna is roughly comparable to Montreal with regard to temperatures in the warm season, size of population, and number of SIDS cases. Although the Viennese study was powerful enough to detect even smaller effects, the Montrealean results could not be confirmed. The Viennese results do not support the hypothesis of a strong effect of maximum ambient temperature on the risk of SIDS during the warm season.</description><identifier>ISSN: 1932-6203</identifier><identifier>EISSN: 1932-6203</identifier><identifier>DOI: 10.1371/journal.pone.0184312</identifier><identifier>PMID: 28877228</identifier><language>eng</language><publisher>United States: Public Library of Science</publisher><subject>Age ; Ambient temperature ; Analysis ; Austria ; Biology and Life Sciences ; Data Collection ; Data Interpretation, Statistical ; Earth Sciences ; Environmental health ; Health risk assessment ; Heat ; Hot Temperature ; Humans ; Hypotheses ; Infant ; Infant, Newborn ; Infants ; Medicine and Health Sciences ; Outdoor air quality ; Pediatrics ; People and Places ; Physical Sciences ; Population (statistical) ; Public health ; Quebec ; Risk Factors ; Seasons ; SIDS ; Sleep ; Solvent abuse ; Studies ; Sudden Infant Death - epidemiology ; Sudden infant death syndrome ; Task forces ; Temperature ; Temperature effects ; Warm seasons</subject><ispartof>PloS one, 2017-09, Vol.12 (9), p.e0184312-e0184312</ispartof><rights>COPYRIGHT 2017 Public Library of Science</rights><rights>2017 Waldhoer, Heinzl. This is an open access article distributed under the terms of the Creative Commons Attribution License: http://creativecommons.org/licenses/by/4.0/ (the “License”), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.</rights><rights>2017 Waldhoer, Heinzl 2017 Waldhoer, Heinzl</rights><lds50>peer_reviewed</lds50><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c692t-8652a9dc3f9c7a3c7de5b50efaef893ea1d3dc909a4cff62f07c79d23ac613923</citedby><cites>FETCH-LOGICAL-c692t-8652a9dc3f9c7a3c7de5b50efaef893ea1d3dc909a4cff62f07c79d23ac613923</cites><orcidid>0000-0003-4711-2379</orcidid></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktopdf>$$Uhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC5587259/pdf/$$EPDF$$P50$$Gpubmedcentral$$Hfree_for_read</linktopdf><linktohtml>$$Uhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC5587259/$$EHTML$$P50$$Gpubmedcentral$$Hfree_for_read</linktohtml><link.rule.ids>230,314,727,780,784,864,885,2102,2928,23866,27924,27925,53791,53793,79600,79601</link.rule.ids><backlink>$$Uhttps://www.ncbi.nlm.nih.gov/pubmed/28877228$$D View this record in MEDLINE/PubMed$$Hfree_for_read</backlink></links><search><contributor>Räisänen, Sari Helena</contributor><creatorcontrib>Waldhoer, Thomas</creatorcontrib><creatorcontrib>Heinzl, Harald</creatorcontrib><title>Exploring the possible relationship between ambient heat and sudden infant death with data from Vienna, Austria</title><title>PloS one</title><addtitle>PLoS One</addtitle><description>A non-linear relationship between maximum ambient temperature and number of sudden infant death syndrome (SIDS) cases had been reported for Montreal, Canada, for the warm season. In particular, high maximum ambient temperatures were found to be extra-hazardous for infants. The study was replicated with data from Vienna, Austria, applying the same statistical approach. Vienna is roughly comparable to Montreal with regard to temperatures in the warm season, size of population, and number of SIDS cases. Although the Viennese study was powerful enough to detect even smaller effects, the Montrealean results could not be confirmed. The Viennese results do not support the hypothesis of a strong effect of maximum ambient temperature on the risk of SIDS during the warm season.</description><subject>Age</subject><subject>Ambient temperature</subject><subject>Analysis</subject><subject>Austria</subject><subject>Biology and Life Sciences</subject><subject>Data Collection</subject><subject>Data Interpretation, Statistical</subject><subject>Earth Sciences</subject><subject>Environmental health</subject><subject>Health risk assessment</subject><subject>Heat</subject><subject>Hot Temperature</subject><subject>Humans</subject><subject>Hypotheses</subject><subject>Infant</subject><subject>Infant, Newborn</subject><subject>Infants</subject><subject>Medicine and Health Sciences</subject><subject>Outdoor air quality</subject><subject>Pediatrics</subject><subject>People and Places</subject><subject>Physical Sciences</subject><subject>Population (statistical)</subject><subject>Public health</subject><subject>Quebec</subject><subject>Risk Factors</subject><subject>Seasons</subject><subject>SIDS</subject><subject>Sleep</subject><subject>Solvent abuse</subject><subject>Studies</subject><subject>Sudden Infant Death - epidemiology</subject><subject>Sudden infant death syndrome</subject><subject>Task forces</subject><subject>Temperature</subject><subject>Temperature effects</subject><subject>Warm seasons</subject><issn>1932-6203</issn><issn>1932-6203</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2017</creationdate><recordtype>article</recordtype><sourceid>EIF</sourceid><sourceid>ABUWG</sourceid><sourceid>AFKRA</sourceid><sourceid>AZQEC</sourceid><sourceid>BENPR</sourceid><sourceid>CCPQU</sourceid><sourceid>DWQXO</sourceid><sourceid>GNUQQ</sourceid><sourceid>DOA</sourceid><recordid>eNqNk22L1DAQx4so3nn6DUQLgii4a5s0afNGWI5TFw4OfLi3YZqHbZZusyapd357Zx_u2JV7IYU2TH_zT-afmSx7WRbTktblx6UfwwD9dO0HMy3KpqIleZSdloKSCScFfXywPsmexbgsCkYbzp9mJ6Rp6pqQ5jTzF7fr3gc3LPLUmXztY3Rtb_JgekjOD7Fz67w16caYIYdV68yQ8s5AymHQeRy1xrgbLGBYY7jLbxy-NCTIbfCr_BozBviQz8aYgoPn2RMLfTQv9t-z7Ofnix_nXyeXV1_m57PLieKCpEnDGQGhFbVC1UBVrQ1rWWEsGNsIaqDUVCtRCKiUtZzYola10ISC4iUVhJ5lr3e6WF2Ue6-iREfQDy4YQ2K-I7SHpVwHt4LwR3pwchvwYSEhJKd6I2tuqK1LozRvKwFMMFWSUvGiAl5XtkWtT_vdxnZltEKTAvRHosd_BtfJhf8tGWtqwgQKvNsLBP9rNDHJlYvK9D0Mxo-7c-PB2RZ98w_6cHV7agFYAF6Qx33VRlTOWEEZGswpUtMHKHy0WTmFjWUdxo8S3h8lIJPMbVrAGKOcf__2_-zV9TH79oDF_upTF30_blvwGKx2oArYqsHYe5PLQm7m4s4NuZkLuZ8LTHt1eEH3SXeDQP8CaoMJrw</recordid><startdate>20170906</startdate><enddate>20170906</enddate><creator>Waldhoer, Thomas</creator><creator>Heinzl, Harald</creator><general>Public Library of Science</general><general>Public Library of Science (PLoS)</general><scope>CGR</scope><scope>CUY</scope><scope>CVF</scope><scope>ECM</scope><scope>EIF</scope><scope>NPM</scope><scope>AAYXX</scope><scope>CITATION</scope><scope>IOV</scope><scope>ISR</scope><scope>3V.</scope><scope>7QG</scope><scope>7QL</scope><scope>7QO</scope><scope>7RV</scope><scope>7SN</scope><scope>7SS</scope><scope>7T5</scope><scope>7TG</scope><scope>7TM</scope><scope>7U9</scope><scope>7X2</scope><scope>7X7</scope><scope>7XB</scope><scope>88E</scope><scope>8AO</scope><scope>8C1</scope><scope>8FD</scope><scope>8FE</scope><scope>8FG</scope><scope>8FH</scope><scope>8FI</scope><scope>8FJ</scope><scope>8FK</scope><scope>ABJCF</scope><scope>ABUWG</scope><scope>AFKRA</scope><scope>ARAPS</scope><scope>ATCPS</scope><scope>AZQEC</scope><scope>BBNVY</scope><scope>BENPR</scope><scope>BGLVJ</scope><scope>BHPHI</scope><scope>C1K</scope><scope>CCPQU</scope><scope>D1I</scope><scope>DWQXO</scope><scope>FR3</scope><scope>FYUFA</scope><scope>GHDGH</scope><scope>GNUQQ</scope><scope>H94</scope><scope>HCIFZ</scope><scope>K9.</scope><scope>KB.</scope><scope>KB0</scope><scope>KL.</scope><scope>L6V</scope><scope>LK8</scope><scope>M0K</scope><scope>M0S</scope><scope>M1P</scope><scope>M7N</scope><scope>M7P</scope><scope>M7S</scope><scope>NAPCQ</scope><scope>P5Z</scope><scope>P62</scope><scope>P64</scope><scope>PATMY</scope><scope>PDBOC</scope><scope>PIMPY</scope><scope>PQEST</scope><scope>PQQKQ</scope><scope>PQUKI</scope><scope>PTHSS</scope><scope>PYCSY</scope><scope>RC3</scope><scope>7X8</scope><scope>5PM</scope><scope>DOA</scope><orcidid>https://orcid.org/0000-0003-4711-2379</orcidid></search><sort><creationdate>20170906</creationdate><title>Exploring the possible relationship between ambient heat and sudden infant death with data from Vienna, Austria</title><author>Waldhoer, Thomas ; Heinzl, Harald</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c692t-8652a9dc3f9c7a3c7de5b50efaef893ea1d3dc909a4cff62f07c79d23ac613923</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2017</creationdate><topic>Age</topic><topic>Ambient temperature</topic><topic>Analysis</topic><topic>Austria</topic><topic>Biology and Life Sciences</topic><topic>Data Collection</topic><topic>Data Interpretation, Statistical</topic><topic>Earth Sciences</topic><topic>Environmental health</topic><topic>Health risk assessment</topic><topic>Heat</topic><topic>Hot Temperature</topic><topic>Humans</topic><topic>Hypotheses</topic><topic>Infant</topic><topic>Infant, Newborn</topic><topic>Infants</topic><topic>Medicine and Health Sciences</topic><topic>Outdoor air quality</topic><topic>Pediatrics</topic><topic>People and Places</topic><topic>Physical Sciences</topic><topic>Population (statistical)</topic><topic>Public health</topic><topic>Quebec</topic><topic>Risk Factors</topic><topic>Seasons</topic><topic>SIDS</topic><topic>Sleep</topic><topic>Solvent abuse</topic><topic>Studies</topic><topic>Sudden Infant Death - epidemiology</topic><topic>Sudden infant death syndrome</topic><topic>Task forces</topic><topic>Temperature</topic><topic>Temperature effects</topic><topic>Warm seasons</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Waldhoer, Thomas</creatorcontrib><creatorcontrib>Heinzl, Harald</creatorcontrib><collection>Medline</collection><collection>MEDLINE</collection><collection>MEDLINE (Ovid)</collection><collection>MEDLINE</collection><collection>MEDLINE</collection><collection>PubMed</collection><collection>CrossRef</collection><collection>Opposing Viewpoints in Context (Gale)</collection><collection>Science in Context</collection><collection>ProQuest Central (Corporate)</collection><collection>Animal Behavior Abstracts</collection><collection>Bacteriology Abstracts (Microbiology B)</collection><collection>Biotechnology Research Abstracts</collection><collection>ProQuest Nursing and Allied Health Journals</collection><collection>Ecology Abstracts</collection><collection>Entomology Abstracts (Full archive)</collection><collection>Immunology Abstracts</collection><collection>Meteorological &amp; Geoastrophysical Abstracts</collection><collection>Nucleic Acids Abstracts</collection><collection>Virology and AIDS Abstracts</collection><collection>Agricultural Science Collection</collection><collection>Health &amp; Medical Collection (Proquest)</collection><collection>ProQuest Central (purchase pre-March 2016)</collection><collection>Medical Database (Alumni Edition)</collection><collection>ProQuest Pharma Collection</collection><collection>Public Health Database</collection><collection>Technology Research Database</collection><collection>ProQuest SciTech Collection</collection><collection>ProQuest Technology Collection</collection><collection>ProQuest Natural Science Collection</collection><collection>Hospital Premium Collection</collection><collection>Hospital Premium Collection (Alumni Edition)</collection><collection>ProQuest Central (Alumni) (purchase pre-March 2016)</collection><collection>Materials Science &amp; Engineering Collection</collection><collection>ProQuest Central (Alumni)</collection><collection>ProQuest Central</collection><collection>Advanced Technologies &amp; Aerospace Collection</collection><collection>Agricultural &amp; Environmental Science Collection</collection><collection>ProQuest Central Essentials</collection><collection>Biological Science Collection</collection><collection>AUTh Library subscriptions: ProQuest Central</collection><collection>Technology Collection</collection><collection>Natural Science Collection</collection><collection>Environmental Sciences and Pollution Management</collection><collection>ProQuest One Community College</collection><collection>ProQuest Materials Science Collection</collection><collection>ProQuest Central</collection><collection>Engineering Research Database</collection><collection>Health Research Premium Collection</collection><collection>Health Research Premium Collection (Alumni)</collection><collection>ProQuest Central Student</collection><collection>AIDS and Cancer Research Abstracts</collection><collection>SciTech Premium Collection</collection><collection>ProQuest Health &amp; Medical Complete (Alumni)</collection><collection>Materials Science Database</collection><collection>Nursing &amp; Allied Health Database (Alumni Edition)</collection><collection>Meteorological &amp; Geoastrophysical Abstracts - Academic</collection><collection>ProQuest Engineering Collection</collection><collection>Biological Sciences</collection><collection>Agriculture Science Database</collection><collection>Health &amp; Medical Collection (Alumni Edition)</collection><collection>PML(ProQuest Medical Library)</collection><collection>Algology Mycology and Protozoology Abstracts (Microbiology C)</collection><collection>Biological Science Database</collection><collection>Engineering Database</collection><collection>Nursing &amp; Allied Health Premium</collection><collection>ProQuest advanced technologies &amp; aerospace journals</collection><collection>ProQuest Advanced Technologies &amp; Aerospace Collection</collection><collection>Biotechnology and BioEngineering Abstracts</collection><collection>Environmental Science Database</collection><collection>Materials science collection</collection><collection>Publicly Available Content (ProQuest)</collection><collection>ProQuest One Academic Eastern Edition (DO NOT USE)</collection><collection>ProQuest One Academic</collection><collection>ProQuest One Academic UKI Edition</collection><collection>Engineering collection</collection><collection>Environmental Science Collection</collection><collection>Genetics Abstracts</collection><collection>MEDLINE - Academic</collection><collection>PubMed Central (Full Participant titles)</collection><collection>DOAJ Directory of Open Access Journals</collection><jtitle>PloS one</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Waldhoer, Thomas</au><au>Heinzl, Harald</au><au>Räisänen, Sari Helena</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Exploring the possible relationship between ambient heat and sudden infant death with data from Vienna, Austria</atitle><jtitle>PloS one</jtitle><addtitle>PLoS One</addtitle><date>2017-09-06</date><risdate>2017</risdate><volume>12</volume><issue>9</issue><spage>e0184312</spage><epage>e0184312</epage><pages>e0184312-e0184312</pages><issn>1932-6203</issn><eissn>1932-6203</eissn><abstract>A non-linear relationship between maximum ambient temperature and number of sudden infant death syndrome (SIDS) cases had been reported for Montreal, Canada, for the warm season. In particular, high maximum ambient temperatures were found to be extra-hazardous for infants. The study was replicated with data from Vienna, Austria, applying the same statistical approach. Vienna is roughly comparable to Montreal with regard to temperatures in the warm season, size of population, and number of SIDS cases. Although the Viennese study was powerful enough to detect even smaller effects, the Montrealean results could not be confirmed. The Viennese results do not support the hypothesis of a strong effect of maximum ambient temperature on the risk of SIDS during the warm season.</abstract><cop>United States</cop><pub>Public Library of Science</pub><pmid>28877228</pmid><doi>10.1371/journal.pone.0184312</doi><tpages>e0184312</tpages><orcidid>https://orcid.org/0000-0003-4711-2379</orcidid><oa>free_for_read</oa></addata></record>
fulltext fulltext
identifier ISSN: 1932-6203
ispartof PloS one, 2017-09, Vol.12 (9), p.e0184312-e0184312
issn 1932-6203
1932-6203
language eng
recordid cdi_plos_journals_1936206955
source MEDLINE; DOAJ Directory of Open Access Journals; Public Library of Science; PubMed Central; Free Full-Text Journals in Chemistry; EZB Electronic Journals Library
subjects Age
Ambient temperature
Analysis
Austria
Biology and Life Sciences
Data Collection
Data Interpretation, Statistical
Earth Sciences
Environmental health
Health risk assessment
Heat
Hot Temperature
Humans
Hypotheses
Infant
Infant, Newborn
Infants
Medicine and Health Sciences
Outdoor air quality
Pediatrics
People and Places
Physical Sciences
Population (statistical)
Public health
Quebec
Risk Factors
Seasons
SIDS
Sleep
Solvent abuse
Studies
Sudden Infant Death - epidemiology
Sudden infant death syndrome
Task forces
Temperature
Temperature effects
Warm seasons
title Exploring the possible relationship between ambient heat and sudden infant death with data from Vienna, Austria
url https://sfx.bib-bvb.de/sfx_tum?ctx_ver=Z39.88-2004&ctx_enc=info:ofi/enc:UTF-8&ctx_tim=2024-12-25T05%3A47%3A37IST&url_ver=Z39.88-2004&url_ctx_fmt=infofi/fmt:kev:mtx:ctx&rfr_id=info:sid/primo.exlibrisgroup.com:primo3-Article-gale_plos_&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.genre=article&rft.atitle=Exploring%20the%20possible%20relationship%20between%20ambient%20heat%20and%20sudden%20infant%20death%20with%20data%20from%20Vienna,%20Austria&rft.jtitle=PloS%20one&rft.au=Waldhoer,%20Thomas&rft.date=2017-09-06&rft.volume=12&rft.issue=9&rft.spage=e0184312&rft.epage=e0184312&rft.pages=e0184312-e0184312&rft.issn=1932-6203&rft.eissn=1932-6203&rft_id=info:doi/10.1371/journal.pone.0184312&rft_dat=%3Cgale_plos_%3EA503586563%3C/gale_plos_%3E%3Curl%3E%3C/url%3E&disable_directlink=true&sfx.directlink=off&sfx.report_link=0&rft_id=info:oai/&rft_pqid=1936206955&rft_id=info:pmid/28877228&rft_galeid=A503586563&rft_doaj_id=oai_doaj_org_article_76e3f71ecd6b49a595c121c604a674fb&rfr_iscdi=true