<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0035-001X</journal-id>
<journal-title><![CDATA[Revista mexicana de física]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. mex. fis.]]></abbrev-journal-title>
<issn>0035-001X</issn>
<publisher>
<publisher-name><![CDATA[Sociedad Mexicana de Física]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0035-001X2007001000028</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Nota sobre la naturaleza del calor en la termodinámica relativista]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Sandoval-Villalbazo]]></surname>
<given-names><![CDATA[A]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[García-Colín]]></surname>
<given-names><![CDATA[L.S]]></given-names>
</name>
<xref ref-type="aff" rid="A02"/>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,Universidad Iberoamericana Departamento de Física y Matemáticas ]]></institution>
<addr-line><![CDATA[México D.F]]></addr-line>
<country>México</country>
</aff>
<aff id="A02">
<institution><![CDATA[,Universidad Autónoma Metropolitana Departamento de Física ]]></institution>
<addr-line><![CDATA[México D.F.]]></addr-line>
<country>México</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>08</month>
<year>2007</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>08</month>
<year>2007</year>
</pub-date>
<volume>53</volume>
<fpage>148</fpage>
<lpage>149</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0035-001X2007001000028&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0035-001X2007001000028&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0035-001X2007001000028&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[Un argumento muy simple muestra que la inclusión del flujo de calor en el tensor ímpetu-energía relativista tiene limitaciones que provienen de la existencia de un término proporcional a la aceleración hidrodinámica. Más aún, su justificación a partir de la teoría cinética relativista limita su validez sólo al fluido ideal.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[It is shown by means of a simple argument that the introduction of the heat flux in the relativistic energy-momentum tensor yields certain limitations that can be traced back to the existence of a term proportional to the hydrodynamic acceleration. Moreover, this acceleration term can only be properly justified in the case of a simple ideal fluid.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[Relatividad general]]></kwd>
<kwd lng="es"><![CDATA[teoría cinética]]></kwd>
<kwd lng="es"><![CDATA[irreversibilidad]]></kwd>
<kwd lng="en"><![CDATA[General relativity]]></kwd>
<kwd lng="en"><![CDATA[kinetic theory]]></kwd>
<kwd lng="en"><![CDATA[irreversibility]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[ <p align="center"><font face="verdana" size="4"><b>Nota sobre la naturaleza del calor en la termodin&aacute;mica relativista</b></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="2"><b>A. Sandoval&#150;Villalbazo* y L.S. Garc&iacute;a&#150;Col&iacute;n**</b></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><i>* Departamento de F&iacute;sica y Matem&aacute;ticas, Universidad Iberoamericana, Prolongaci&oacute;n Paseo de la Reforma 880, M&eacute;xico D.F. 01210, M&eacute;xico.</i></font></p>     <p align="justify"><font face="verdana" size="2"><i>** Departamento de F&iacute;sica, Universidad Aut&oacute;noma Metropolitana&#150;Iztapalapa, </i><i>Av. Pur&iacute;sima y Michoacan S/N, M&eacute;xico D.F. 09340, M&eacute;xico. Also at El Colegio Nacional, Luis Gonz&aacute;lez Obreg&oacute;n 23, Centro Hist&oacute;rico, M&eacute;xico D. F. 06020, M&eacute;xico.</i></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2">Recibido el 1 de mayo de 2006    <br>   Aceptado el 1 de noviembre de 2006</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2"><b>Resumen</b></font></p>     <p align="justify"><font face="verdana" size="2">Un argumento muy simple muestra que la inclusi&oacute;n del flujo de calor en el tensor &iacute;mpetu&#150;energ&iacute;a relativista tiene limitaciones que provienen de la existencia de un t&eacute;rmino proporcional a la aceleraci&oacute;n hidrodin&aacute;mica. M&aacute;s a&uacute;n, su justificaci&oacute;n a partir de la teor&iacute;a cin&eacute;tica relativista limita su validez s&oacute;lo al fluido ideal.</font></p>     <p align="justify"><font face="verdana" size="2"><b>Descriptores: </b>Relatividad general; teor&iacute;a cin&eacute;tica; irreversibilidad.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Abstract</b></font></p>     <p align="justify"><font face="verdana" size="2">It is shown by means of a simple argument that the introduction of the heat flux in the relativistic energy&#150;momentum tensor yields certain limitations that can be traced back to the existence of a term proportional to the hydrodynamic acceleration. Moreover, this acceleration term can only be properly justified in the case of a simple ideal fluid.</font></p>     <p align="justify"><font face="verdana" size="2"><b>Keywords: </b>General relativity; kinetic theory; irreversibility.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2">PACS: 04.20.&#150;q; 51.10.+y; 05.70.Ln</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2"><a href="/pdf/rmf/v53s4/v53s4a28.pdf">DESCARGAR ART&Iacute;CULO EN FORMATO PDF</a></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Agradecimientos</b></font></p>     <p align="justify"><font face="verdana" size="2">Los autores desean expresar su agradecimiento a la Dra. Ana Laura Garc&iacute;a&#150;Perciante por sus valiosos comentarios durante la elaboraci&oacute;n de este trabajo. Este trabajo fue parcialmente apoyado por CONACyT proyecto 41081&#150;F.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Referencias</b></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">1. C. Eckart, <i>Phys. Rev. </i><b>58</b> (1940) 919.</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8394987&pid=S0035-001X200700100002800001&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">2. L.S. Garc&iacute;a&#150;Col&iacute;n y A. Sandoval&#150;Villalbazo, <i>J. Nonequilibrium Thermodinamics. </i><b>31</b> (2006) 11.</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8394988&pid=S0035-001X200700100002800002&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">3. A. Sandoval&#150;Villalbazo y L.S. Garc&iacute;a&#150;Col&iacute;n, XXVIII Spanish Relativity Meeting proceedings, AIP Conference proceedings <b>841 </b>(2006) 603.</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8394989&pid=S0035-001X200700100002800003&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">4. S.R. de Groot y P. Mazur, <i>Non&#150;equilibrium Thermodynamics </i>(Dover publications, Minneola, N.Y., 1984).</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8394990&pid=S0035-001X200700100002800004&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">5. C. Cercignani and G.M. Kremer, <i>The relativistic Boltzmann equation: Theory and applications </i>(Birkh&auml;user Verlag, Nasel, 2002).</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8394991&pid=S0035-001X200700100002800005&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> ]]></body><back>
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