<?xml version="1.0" encoding="UTF-8"?><?xml-stylesheet type="text/xsl" href="static/style.xsl"?><OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd"><responseDate>2026-06-28T15:12:21Z</responseDate><request verb="GetRecord" identifier="oai:docta.ucm.es:20.500.14352/64758" metadataPrefix="marc">https://docta.ucm.es/rest/oai/request</request><GetRecord><record><header><identifier>oai:docta.ucm.es:20.500.14352/64758</identifier><datestamp>2023-08-11T07:46:18Z</datestamp><setSpec>com_20.500.14352_14</setSpec><setSpec>col_20.500.14352_15</setSpec></header><metadata><record xmlns="http://www.loc.gov/MARC21/slim" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:doc="http://www.lyncode.com/xoai" xsi:schemaLocation="http://www.loc.gov/MARC21/slim http://www.loc.gov/standards/marcxml/schema/MARC21slim.xsd">
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      <subfield code="a">Elliot, C. M.</subfield>
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      <subfield code="a">Herrero, Miguel A.</subfield>
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      <subfield code="a">King, J. R.</subfield>
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      <subfield code="a">Ockendon, J.R.</subfield>
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      <subfield code="c">1986</subfield>
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      <subfield code="a">In this paper we consider the limit m→+∞ of solutions of the porous-medium equation ut = ∇•(um∇u)(xεRN), with N > 1. We conjecture that, for initial data with a unique maximum, the evolution is characterized by the onset of a ‘mesa’ region, in which the solution is nearly spatially independent, surrounded by a region in which u is nearly equal to its initial value. The transition between these regions occurs near a surface which is identified with the free boundary in a certain Stefan problem which can be studied using variational inequalities. Moreover, singular-perturbation theory can be used to describe the structure of the transition region.</subfield>
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      <subfield code="a">0272-4960</subfield>
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      <subfield code="a">10.1093/imamat/37.2.147</subfield>
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      <subfield code="a">https://hdl.handle.net/20.500.14352/64758</subfield>
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      <subfield code="a">http://imamat.oxfordjournals.org/content/37/2/147.short</subfield>
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      <subfield code="a">http://imamat.oxfordjournals.org</subfield>
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      <subfield code="a">The mesa problem: diffusion patterns for ut=∇⋅(um∇u) as m→+∞ .</subfield>
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