Resonance systems of millimeter wave oscillators
An analysis of open resonators specially designed for millimeter wave sources which are characterized by high frequency stability is presented. The obtained numerical results and experimental data have been used to improve the characteristics of oscillating systems formed by a two-mirror resonator with metal rod inside. To proceed the preselection of modes in the given frequency region the flat mirror of a conventional Fabri-Perot hemispherical open resonator have been replaced by a specially constructed mirror with a stepwise cross-section. The further tune axial mode filtration and the complete transverse modes suppression have been achieved by the insertion of a metal rectangular rod into the resonant cavity. The determining of parameters of the stepwise mirror and the rod is based on a detail theoretical investigation of the problem of wave scattering from these structures. Experimental results are in good agreement with numerical data. The designed open resonators can be used for generation of electromagnetic waves in the frequency region from 30 to 150 GHz. 1. The analysis of electromagnetic fields in open quasi-optical resonators has been extensively investigated because of its importance for solid-state sources design and for measurement problems in the millimeter wave band (Kotserzhinsky et al (1)). An introduction of GaAs and InP active elements into high Q circuits led to the development of millimeter wave oscillators characterized by rather high output power (about 100 mWt) and by a high frequency stability. The quality of a signal depends on the Q-factor of a circuit used in oscillators.
Open resonators with inhomogeneities
An analysis of electromagnetic properties of an Open Resonator (OR) with perfectly conducting cylindrical inhomogeneities is presented. The inhomogeneities of three types were studied. In the first case the conducting thin circular cylinder with a longitudinal slot is considered. This cavity-backed aperture possess the resonance features. It is shown that such cylindrical screen may be used in order to control the OR properties. The case of the conducting cylinders with rectangular and circular cross-section are considered too. It is shown that the inhomogeneity of small cross-sectional wave dimensions can both be imperceptible for the OR-field and efficiently scatter it, depending on location of the inhomogeneity in the OR. The theoretical analysis and experimental results are presented. The stationary wave model of the OR field is used in the theoretical analysis of scattering from cylindrical inhomogeneities. The generator of the cylindrical obstacles is parallel to the H vector of the incident field. The experiments were carried out in the millimeter wave band with the OR having spherical and flat mirrors. The numerical results are in a good agreement with the experimental data.
Human reproduction: irrational but in most cases morally defensible
While I am inclined to agree that in most cases a choice to become pregnant and bring to birth a child is an irrational choice, unlike Professor Hayry,1 I believe that choosing to do so is far from being necessarily immoral. In fact I will argue that it is often these irrational (but morally defensible) choices which make human life the valuable commodity many of us believe it is.

Hayry argues that not only is the choice to have children always an irrational choice, but also it is necessarily an immoral choice. Thus, for Hayry “human reproduction is fundamentally immoral”.1 He claims it is important to point out to prospective parents that their urge to have children is irrational. From this, he argues, it follows that once this is accepted the use of advance technologies to assist conception should be reassessed, and furthermore, the irrationality and immorality of having children should become a legitimate part of guidance given to those expressing a wish to have children.

According to Hayry the reason it is irrational and immoral to choose to bring to birth a child is that “having a child can always realistically lead to the worse possible outcome, when the alternative is not having a child”.1 He argues that when people consider having children they are faced with the choice between deciding not to have children and thus harming or benefiting no-one (this, it is argued has a value of zero), or having children where this life may be good or bad, and thus the value of this choice can be …