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This paper discusses the construction of inverse solutions with optimal resolution kernels and applications of them in the reconstruction of the generators of the EEG/MEG. On the basis of the framework proposed by Backus and Gilbert [1967], we show how a family of well-known solutions ranging from the minimum norm method to the generalized Wiener estimator can be derived. It is shown that these solutions have optimal properties in some well-defined sense since they are obtained by optimizing either the resolution kernels and/or the variances of the estimates. New proposals for the optimization of resolution are made. In particular, a method termed "weighted resolution optimization" (WROP) is introduced that deals with the difficulties inherent to the method of Backus and Gilbert [1967], from both a conceptual and a numerical point of view. One-dimensional simulations are presented to illustrate the concept and the interpretation of resolution kernels. Three-dimensional simulations shed light on the resolution properties of some linear inverse solutions when applied to the biomagnetic inverse problem. The simulations suggest that a reliable three-dimensional electromagnetic tomography based on linear inverse solutions cannot be constructed, unless significant a priori information is included. The relationship between the resolution kernels and a definition of spatial resolution is emphasized. Special consideration is given to the use of resolution kernels to assess the properties of linear inverse solutions as well as for the design of inverse solutions with optimal resolution kernels.

This double-blind, placebo-controlled clinical trial of yohimbine hydrochloride included 86 patients with erectile dysfunction and without clearly detectable organic or psychologic causes. The patient group ful®lled all entry criteria; 85 of these could be considered for the Safetyrespectively 83 for the Intention-to-treat (ITT)-analysis. Yohimbine was administered orally in a dosage of 30 mg a day (two 5mg tablets three times daily) for eight weeks. Patients were seen for follow-up after four weeks' treatment, and for a ®nal visit after eight weeks.Ef®cacy evaluation was based on both subjective and objective criteria. Subjective criteria included improvement in sexual desire, sexual satisfaction, frequency of sexual contacts, and quality of erection (penile rigidity) during sexual contact/intercourse. Objective criteria of outcome were based on improvement in penile rigidity determined by use of polysomnography in the sleep laboratory. Overall Yohimbine was found signi®cantly more effective than placebo in terms of response rate: 71 vs 45%.Yohimbine was well-tolerated: Only 7% of patients rated tolerability fair or poor, and most adverse experiences were mild. There was no serious adverse event.

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