The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Let κ be the curvature of a smooth closed curve of length 2π. The 2π-periodic eigenvalue problems u″−gκ2u+λu=0, where g is a real parameter, are considered and upper and lower bounds for their principal eigenvalues are obtained. The bounds are of isoperimetric type and characterize uniquely the curve in the case where equality occurs.
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.