Resistive cooling circuits for charged particle traps using crystal resonators.

The paper addresses a novel method to couple a signal from charged particles in a Penning trap to a high Q resonant circuit using a crystal resonator. Traditionally, the trap capacity is converted into a resonator by means of an inductance. The tuned circuit's Q factor is directly linked to the input impedance "seen" by the trapped particles at resonance frequency. This parallel resonance impedance is a measure of the efficiency of resistive cooling and thus it should be optimized. We propose here a commercially available crystal resonator since it exhibits a very high Q value and a parallel resonance impedance of several MΩ. The possibility to tune the parallel resonance frequency of the quartz results in filter behavior that allows covering a range of some tens of its 3dB bandwidth by means of tuning.

[Electro-ophthalmological responses in inflammations of various sections of the orbital visual pathways (author's transl)]. / Das Verhalten der elektroophthalmologischen Antwort bei Entzündungen verschiedener orbitaler Sehbahnanteile.

In a study of electro-ophthalmological responses of the EOG, the photopic and scotopic ERG, the OP and the VECP, in combination with fluorescein angiography and computerized perimetry, in 34 patients suffering from uveitis, chorioretinitis (lesions near the macula and at the periphery), papillitis or retrobulbar neuritis, the following results were obtained: Uveitis and chorioretinitis with lesions either near the macula or at the retinal periphery produce different responses; generally, pathologic responses of the EOG and ERG and normal VECP are obtained in cases of uveitis. Peripheral chorioretinal lesions lead to a diminution of the scotopic ERG, OP and EOG, in contrast to lesions near the macula, in which pathologically diminished amplitudes of the photopic ERG and VECP are found. In papillitis and retrobulbar neuritis, however, the most important peculiarity is the increase in latency and the decrease in amplitudes of the VECP, especially in retrobulbar neuritis.

[Electroophthalmologic and fluorescein angiographic studies in a case of exudative retinal detachment with spontaneous healing]. / Elektroophthalmologische und fluoreszenzangiographische Untersuchungen bei einem Fall von exsudativer Netzhautablösung mit Selbstheilung.

Electroophthalmological and fluorescein angiographic studies were performed on a 13 year old girl with exsudative detachment of the retina during a hypertensive crisis. The ERG showed a significant reduction during the course of the detachment. After healing the ERG values had improved as compared to those values recorded during the acute illness, but never reached normal levels. The lesions of the retina and the pigment epithelium caused by the detachment were responsible for pathological EOG. The fluorescein angiography showed circumscript and conglomerate lesions in the pigment epithelium.