N. Tsagas

Magnetic Stimulation in the Treatment of Partial Seizures

We have recently demonstrated that Magnetoencephalographic (MEG) brain measurements in patients with seizure disorders show significant MEG activity often in the absence of conventional EEG abnormalities. We localized foci of seizure activity using the mapping technique characterized by the ISO-Spectral Amplitude (ISO-SA) on the scalp distribution of specified spectral components or frequency bands of the emitted MEG Fourier power spectrum. In addition, using an electronic device, we utilized the above recorded activity to emit back the same intensity and frequency of magnetic field to the presumed epileptic foci. Using this method we were able, over the past two years, successfully to attenuate seizure activity in a cohort of over 100 patients with various forms of epilepsy. We now present in more detail three randomly selected patients with partial seizures in whom application of an external artificial magnetic field of low intensity produced a substantial attenuation of seizure frequency during an observation period extending from 10 to 14 months. All patients had previously obtained only partial response to conventional anticonvulsant therapy. Attenuation in seizure frequency was associated with normalization of the MEG activity. These cases demonstrate that artificial magnetic treatment may be a valuable adjunctive procedure in the management of partial seizures. The possible mechanisms underlying the anticonvulsant properties of magnetic stimulation at both cellular and systemic levels are discussed. Specifically, since the pineal gland has been shown to be a magnetosensitive organ which forms part of a combined compass-solar clock system, and since it exerts an inhibitory action on seizure activity in both experimental animals and humans, we discuss the potential pivotal role of the pineal gland in the long term anticonvulsant effects of external artificial magnetic stimulation.

Technoeconomic assessment of a building-integrated PV system for electrical energy saving in residential sector

This paper describes the installation, technical characteristics, operation and economic evaluation of a grid-connected building-integrated photovoltaic system (BIPV) installed in Northern Greece, and in particular in the city of Kastoria. The technical and economical factors are examined using a computerized renewable energy technologies (RETs) assessment tool. A number of different economic and financial feasibility indices are calculated for different financing scenarios in order to assess the gross return of the investment. Useful conclusions were drawn regarding the feasibility of BIPV systems and their potential for increased energy market penetration.

Technoeconomic assessment of a hybrid solar/wind installation for electrical energy saving

This paper reports the technical feasibility and economic viability of a hybrid solar/wind grid connected system for electrical and thermal energy production, covering the energy demand of a typical residence in the city of Xanthi (Greece). The technical characteristics of the solar and wind energy subsystems are given. The energy output provided by the hybrid energy system was estimated using a simulation program, which is based on the Monte Carlo method, for reading the solar radiation and wind potential data. The auxiliary energy supply is based on the output of a combined-cycle natural gas power plant, recently constructed in the Thrace region. The economic analysis of the proposed hybrid solar/wind system is performed using the life cycle savings (LCS) method and the payback period (PBP) of the initial capital cost is determined.

Melatonin as a Proconvulsive Hormone in Humans

The pineal gland and melatonin exert a major influence in the control of brain electrical activity and have been shown to be involved in seizure and sleep mechanisms. Since pinealectomy has been reported to result in seizures in experimental animals, it is assumed that melatonin has anticonvulsant properties. Indeed, limited studies in humans with temporal lobe epilepsy indicate that melatonin attenuates seizure activity. In the present communication we present evidence, based on magnetoencephalographic (MEG) brain measurements, that melatonin may exert proconvulsive activity in humans as well. The proconvulsive properties of melatonin may explain several phenomena associated with epilepsy such as the increased occurrence of seizures at night when melatonin plasma levels are 5 to 8-fold higher than during the day and the observed exacerbation of seizures premenstrually and during pregnancy as well as the attenuation of seizures in the menopause. Furthermore, our findings suggest that anticonvulsants which decrease melatonin secretion, such as the benzodiazepines, may exert their antiepileptic activity by attenuating nocturnal melatonin secretion. Finally, we propose that patients with nocturnal epilepsy or those experiencing exacerbation of seizures premenstrually may benefit from the administration of agents which block the secretion or action of melatonin.

Design, optimisation and conversion-efficiency determination of a line-focus parabolic-trough solar-collector (PTC)

PTCs are the preferred type of collector used for steam generation, due to their ability to work at high temperatures with high efficiencies. The results produced from a simulation program, showing the variation of collectors efficiency as a function of heat transfer fluid flux, pipe diameter, solar radiation intensity and active area of the PTC, are presented.

Magnetic fields and seasonality of affective illness: Implications for therapy

Seasonal affective disorder is characterized by recurrent winter depression associated with hypersomnia, overeating, and carbohydrate craving. The severe form of winter depression affects about 5% of the general population and is believed to be caused by light deficiency. About 70%-80% of patients with winter depression experience attenuation of symptoms when exposed to bright light therapy. Hypotheses pertaining to the pathogenesis of winter depression implicate the effects of light on different characteristics of circadian rhythms. One of the environmental factors which may be implicated, in addition to light, in the pathophysiology of winter depression is the geomagnetic field. There is strong indication that the pineal gland is a magnetosensitive system and that changes in the ambient magnetic field alter melatonin secretion and synchronize the circadian rhythms. In man, shielding of the ambient magnetic field significantly desynchronizes circadian rhythms which could be gradually resynchronized after application of magnetic fields. The strength of the environmental magnetic field diminishes during the winter months, leading to increased susceptibility for desynchronization of circadian rhythms. Thus, since the acute application of magnetic fields in experimental animals resembles that of acute exposure to light with respect to melatonin secretion (i.e., suppression of melatonin secretion), magnetic treatment might be beneficial for patients with winter depression. In addition, since the environmental light and magnetic fields, which undergo diurnal and seasonal variations, influence the activity of the pineal gland, we propose that a synergistic effect of light and magnetic therapy in patients with winter depression would be more physiological and, therefore, superior to phototherapy alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Technology, thermal analysis and economic evaluation of a sunspace located in northern Greece

Abstract This paper discusses the thermal analysis and economic performance of an attached sunspace, used in a conventional dwelling environment. The sunspace is a modified greenhouse with special geometry of glazed inclined roof and inclined glazed walls and is capable to operate only as a completely passive system. New solar radiation and ambient temperature data for the area of northern Greece is presented. The calculation of thermal loads using the degree–day method and the annual auxiliary energy requirements of the residence are estimated using the unutilizability method (UU method). The economic analysis is performed using the Life Cycle Savings (LCS) method, modified to comply with the Greek tax policy, and the cost-optimum collectors area determination using the P-chart method. Also, the payback period of the initial investment is estimated, after taking under consideration economic factors applied to Greek energy policy.

Is the Pineal Gland Involved in the Pathogenesis of Endometrial Carcinoma

The pathogenesis of endometrial carcinoma, which is the most common malignant neoplasm of the female genital tract, is unknown. It is believed that a prolonged period of increased estrogenic exposure unopposed by progesterone may underlie the malignant transformation of the endometrial cells. In the following communication, we propose that deficient melatonin functions may be an additional endocrine factor implicated in the pathogenesis of endometrial carcinoma. This hypothesis is based on the observations that: (a) melatonin has antiestrogenic properties; (b) melatonin stimulates progesterone production which opposes the action of estrogens; (c) an increased rate of endometrial hyperplasia, a premalignant condition, has been noted during the winter, a time of year associated with diminished melatonin secretion; (d) an increased incidence of anovulatory cycles, which is a risk factor for endometrial carcinoma, occurs in the winter; (e) melatonin secretion decreases sharply during the menopause, a period associated with an increased risk of endometrial carcinoma; (f) obesity, which is a major risk factor for endometrial carcinoma, is associated with impaired circadian melatonin secretion; (g) diabetes mellitus, which is an additional risk factor for endometrial carcinoma, is associated with decreased melatonin secretion and an increased rate of pineal calcification; and (h) the prevalence of endometrial carcinoma is lower in the black population compared to the white population. Similarly, the incidence of pineal calcification, which reflects the secretory activity of the gland, is significantly lower in the African and American black populations as compared to the white population.(ABSTRACT TRUNCATED AT 250 WORDS)

Localization and Cure of Epileptic Foci with the Use of Meg Measurements

Systematic studies with pathological subjects with focal and general epilepsies using magnetoencephalographic (MEG) measurements showed significant brain activities even if they are not present in the electroencephalogram EEG. Using a mapping technique characterized by an isospectral amplitude (ISO-SA) of the scalp distribution of specified spectral components or frequency bands of the MEG power spectrum we were able to localize the epileptic foci. This localization of epileptic foci gives us information on the emitted magnetic field intensity and frequency for each focal point on the map of the patient. Using this information we can cure the patient by adjusting an electronic device which can emit back to the specific scalp point a magnetic field of the same intensity and frequency as the one which-is emitted from it. The principle of this technique is based on the physical phenomenon of Youngs double-slit experiment by which under certain condition light plus light gives darkness.

Magnetic Stimulation Can Modulate Seizures in Epileptic Patients

Objective: The aim of this study is to investigate the influence of external magnetic stimulation (EMS) in epileptic patients using magnetoencephalographic (MEG) measurements and non-linear analytic techniques. Methods: The examined group consisted of 15 men aged 19-56 years (mean: 39.5±11.3) and 15 women aged 15-53 years (mean: 36.7±11.4 ). For each one the magnetic activity was recorded from 32 points for each temporal lobe. External magnetic stimulation (EMS) with proper field characteristics (intensity: 1-7.5 pT, frequency: the α-rhythm of the patient (8-13 Hz)) was applied in the frontal, occipital and temporal lobes for 2 to 6 minutes and the emitted brain magnetic activity was recorded again. In order to investigate if there is any alteration in the MEG complexity underlying the neural dynamics characterizing the pathologic brain before and after the EMS, chaotic analysis approach was applied for the estimation of the dimensional analysis of the existing strange attractors. Results: The application of EMS resulted in rapid attenuation of the MEG activity of epileptic patients. The obtained results of the dimensionality calculation provide a shift from lower to higher dimensional values. Such a shift is an indication that we are dealing with a chaotic system similar with the one characterizing normal subjects. Conclusions: The increased values of the dimensional complexity and the lower activity of the MEG after the application of EMS strongly supports the beneficial effects of EMS in epileptic patients.