<?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>0120-419X</journal-id>
<journal-title><![CDATA[Revista Integración]]></journal-title>
<abbrev-journal-title><![CDATA[Integración - UIS]]></abbrev-journal-title>
<issn>0120-419X</issn>
<publisher>
<publisher-name><![CDATA[Universidad Industrial de Santander]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0120-419X2013000100005</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Cota superior para el primer valor propio del problema de Steklov]]></article-title>
<article-title xml:lang="en"><![CDATA[Upper bound for the first eigenvalue of the Steklov problem]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[MONTAÑO CARREÑO]]></surname>
<given-names><![CDATA[ÓSCAR ANDRÉS]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,Universidad del Valle Departamento de Matemáticas ]]></institution>
<addr-line><![CDATA[Cali ]]></addr-line>
<country>Colombia</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>06</month>
<year>2013</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>06</month>
<year>2013</year>
</pub-date>
<volume>31</volume>
<numero>1</numero>
<fpage>53</fpage>
<lpage>58</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.co/scielo.php?script=sci_arttext&amp;pid=S0120-419X2013000100005&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.co/scielo.php?script=sci_abstract&amp;pid=S0120-419X2013000100005&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.co/scielo.php?script=sci_pdf&amp;pid=S0120-419X2013000100005&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[Sea Br una bola n-dimensional dotada con una métrica rotacionalmente invariante y con curvaturas seccionales radiales no positivas. Si v es el primer valor propio de Steklov y h es la curvatura media sobre el borde de la bola, nosotros demostramos que v &#8804; h con igualdad si y solo si Br es la bola con la métrica usual de &#8477;n.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[Let Br be an n-dimensional ball endowed with a rotationally in- variant metric and with non-positive radial sectional curvatures. If v is the first Steklov eigenvalue and h is the mean curvature on the boundary of the ball, we prove that v &#8804; h. Equality holds only when Br is the ball endowed with the standard metric of &#8477;n.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[Curvatura seccional]]></kwd>
<kwd lng="es"><![CDATA[curvatura media]]></kwd>
<kwd lng="es"><![CDATA[valor propio de Steklov]]></kwd>
<kwd lng="en"><![CDATA[Sectional curvature]]></kwd>
<kwd lng="en"><![CDATA[mean curvature]]></kwd>
<kwd lng="en"><![CDATA[Steklov eigenvalue]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[   <font size="2" face="Verdana">     <p align="center"><font size="4"><i><b>Cota superior para el primer valor propio del    <br> problema de Steklov</b></i></font></p>      <p align="center">&Oacute;SCAR ANDR&Eacute;S MONTA&Ntilde;O CARRE&Ntilde;O <sup>*</sup>    <br>    <br> Universidad del Valle, Departamento de Matem&aacute;ticas, Cali, Colombia.</p> <hr>     <p align="justify"><b><i>Resumen</i></b>. Sea <i>B<sub>r</sub></i> una bola <i>n</i>-dimensional dotada con una m&eacute;trica rotacionalmente invariante y con curvaturas seccionales radiales no positivas. Si <i>v</i> es el primer valor propio de Steklov y <i>h</i> es la curvatura media sobre el borde de la bola, nosotros demostramos que <i>v</i> &le; <i>h</i> con igualdad si y solo si <i>B<sub>r</sub></i> es la bola con la m&eacute;trica usual de &#8477;<sup>n</sup>.    <br> <i><b>Palabras claves:</b></i> Curvatura seccional, curvatura media, valor propio de Steklov.    <br> <i><b>MSC2010:</b></i> 35P15, 53C20, 53C42, 53C43</p> <hr>     <p align="center"><font size="3"><b><i>Upper bound for the first eigenvalue of the Steklov    ]]></body>
<body><![CDATA[<br> problem</i></b></font></p>      <p align="justify"><i><b>Abstract.</b></i> Let Br be an n-dimensional ball endowed with a rotationally in- variant metric and with non-positive radial sectional curvatures. If <i>v</i> is the first Steklov eigenvalue and <i>h</i> is the mean curvature on the boundary of the ball, we prove that <i>v</i> &le; <i>h</i>. Equality holds only when <i>B<sub>r</sub></i> is the ball endowed with the standard metric of &#8477;<sup>n</sup>.    <br> <i><b>Keywords:</b></i> Sectional curvature, mean curvature, Steklov eigenvalue.</p>  <hr>     <p align="justify">Texto Completo disponible en <a href ="pdf\rein\v31n1\v31n1a05.pdf" target="_blank">PDF</a></p> <hr>     <p align="left"><font size="3"><b><i>Referencias</i></b></font></p>      <!-- ref --><p align="justify">&#91;1&#93; Escobar J.F., &quot;The Geometry of the first Non-Zero Stekloff Eigenvalue&quot;, <i>J. Funct. Anal.</i> 150 (1997), no. 2, 544-556.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000018&pid=S0120-419X201300010000500001&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></p>      <!-- ref --><p align="justify">&#91;2&#93; Escobar J.F., &quot;A comparison theorem for the first non-zero Steklov Eigenvalue&quot;, <i>J. Funct. Anal.</i> 178 (2000), no. 1, 143-155.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000020&pid=S0120-419X201300010000500002&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></p>      <!-- ref --><p align="justify">&#91;3&#93; Monta&ntilde;o O.A., &quot;The First Non-zero Stekloff Eigenvalue for conformal metrics on the ball&quot;, <i>Preprint.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000022&pid=S0120-419X201300010000500003&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></i></p>      <!-- ref --><p align="justify">&#91;4&#93; Payne L.E., &quot;Some isoperimetric inequalities for harmonic functions&quot;, <i>SIAM J. Math. Anal.</i> 1 (1970), 354-359.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000024&pid=S0120-419X201300010000500004&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></p>      <!-- ref --><p align="justify">&#91;5&#93; Stekloff M.W., &quot;Sur les probl&egrave;mes fondamentaux de la physique math&eacute;matique&quot;, <i>Ann. Sci. &Eacute;cole Norm. Sup.</i> 19 (1902),    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000026&pid=S0120-419X201300010000500005&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> 445-490.</p>      <!-- ref --><p align="justify">&#91;6&#93; Schoen R. and Yau S.T., <i>Lectures on Differential Geometry,</i> International Press, 1994.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000028&pid=S0120-419X201300010000500006&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></p>      <!-- ref --><p align="justify">&#91;7&#93; Weinstock R., &quot;Inequalities for a classical eigenvalue problem&quot;, <i>J. Rational Mech. Anal.</i> 3 (1954), 745-753.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000030&pid=S0120-419X201300010000500007&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></p>  <hr>     <p align="justify"><sup>*</sup><i>E-mail:</i> <a href="mailto:oscar.montano@correounivalle.edu.co">oscar.montano@correounivalle.edu.co</a>.    ]]></body>
<body><![CDATA[<br> Recibido: 16 de febrero de 2013, Aceptado: 21 de junio de 2013.</p> </font>      ]]></body><back>
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</article>
