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Lean fuel burning is considered as one of the most prominent methods to achieve the low temperature combustion reduces nitrogen oxides (NOx) emissions. However, as a result lean burning suffers from strong flame instabilities and a very lean operating condition near to the flame quenching limit is associated with the high risk of lean blowout (LBO) which has to be avoided. Therefore, the capability to sense the origin of LBO will provide substantial settlements to improve combustor reliability in order to achieve optimum performance, to extend engine life and to reduce maintenance cost. From the last few decades, many engine manufacturers and research institutions are working on the novel approaches based on the lean combustion concepts. For achieving desired objects, several passive control technologies were studied to improve the flame stabilization by modifying the injector geometry or flame holders in a permanent way. Adding to this, Non thermal plasma assisted combustion (NTPAC) technology is the most encouraging techniques to actively control the control the flow and combustion dynamics in consonance with real-time operating conditions without altering the combustor design. NTPAC improves the efficiency of combustors, increases flame stabilization, enhances low temperature oxidation, and extends the LBO limits, in the meantime it also reduces the significant amount of nitrogen oxides (NOx). From literature review it has been concluded that the effects of NTPAC is broadly classified into three ways: thermal effects, kinetic effects, and transport effects. Among all the NTPAC technologies, the dielectric barrier discharge (DBD) is widely considered and credit goes to the simplicity of its design and the wide range of operating modes.However, the effects of NTPAC on flame stability and LBO limits are not clearly understood yet, due to the complexity of each specific process involves in the plasma combustion. Therefore, for the better understanding of NTPAC processes, an experimental study was performed which investigates the behavior of premixed methane/air flames close to LBO limits at different operating conditions using plasma assisted lifted swirl combustor. The combustor was equipped with ring-needle shaped plasma actuator operated by sinusoidal generator at the maximum frequency of 20 kHz directly coupled with flame near to the nozzle. The test system was covered by faraday cage to avoid interference of electromagnetic fields produced through plasma discharge. The plasma actuator configuration involves a tungsten needle having a diameter of 1 mm and length equal to 46 mm. The needle was placed at the center of nozzle which referred as a high voltage (HV) electrode. However, the nozzle was acted as a grounded (GND) electrode. Electrical characterization of combustion characteristics was performed at different plasma actuation conditions and air/fuel mass flow rates. Flame behavior was also captured by high resolution CCD camera by predicting the recirculation zone produced by plasma, have the benefits of generating compact flames and allowing the high reaction rates. Acoustic measurements were performed using high sensitivity microphone. Furthermore, post processing of the microphone data involved application of Fast Fourier Transform (FFT).

The study was an open uncontrolled pilot trial to test the efficacy and the tolerability of acetazolamide in a group of 22 outpatients suffering from migraine with aura (MA) with at least one aura episode in the last 2 months.

Objective.—The study explored the hypothesis that spontaneous nystagmus (Ny) in migraine patients can be triggered or modulated by painful trigeminal stimulation, providing evidence of a functional connection between vestibular and trigeminal systems. Background.—Vertigo attacks are reported by subjects with migraine or a familiar history of migraine, also independently of headache episodes. Idiopathic vertigo is three times more frequent in migraine patients than in controls. Vestibular investigations in migraine patients have consistently demonstrated spontaneous Ny both of central and peripheral origin. Design.—In the first phase of the study 10 outpatients experiencing migraine without aura (MO) and 10 healthy volunteers were submitted to the registration of spontaneous primary-position Ny in the dark by Ulmer's video-ocular-nystagmographic equipment. Two electrodes for electrical stimulation were applied on the supraorbital point of one side of the head and the intensity of stimulation corresponding to pain threshold was calculated. Spontaneous ocular movements were recorded for 5 minutes at baseline and after a sequence of five electric pulses (square waves of .5 Hz frequency and 50 μs duration, at pain threshold intensity). Nystagmographic responses were expressed as latency after stimulation, direction of the quick phase, and duration. The second phase of the study explored, with the same procedure, the effects on Ny of supraorbital versus median nerve stimulation in other 10 MO patients. Responses to stimulation were considered the appearance of de novo Ny after stimulation in subjects without baseline Ny, or the change of the frequency (at last a 50% variation) or of the direction of Ny after stimulation in subjects with baseline Ny. The latency and the duration of responses to stimulation were also calculated. Results.—In the first series supraorbital painful electric stimulation was able to modify or to evoke Ny in 8 of 10 migraineurs and in none of 10 volunteers (Fisher's exact test, P < .01). Both the baseline and the induced Ny were second degree, stationary persistent, with a linear slow phase and were suppressed by visual fixation. In the second series, supraorbital nerve stimulation was able to induce or modify Ny in all of 10 patients but only in 1 patient Ny was induced by median nerve stimulation. Characters of Ny were the same as previously described. Statistical comparison of the responses at the two sites of stimulation was significant (Fisher's exact test, P < .01). In those 7 patients who presented de novo Ny after stimulation it was possible to calculate Ny latency and duration. The mean latency was 25 s (SD: 16, range: 14 to 60). The mean duration was 120 s (SD: 94, range: 20 to 290). Conclusion.—The main result of our study is that in migraine patients painful trigeminal stimulation elicits de novo, or modifies pre-existing spontaneous Ny, generally increasing it. The finding was obtained after trigeminal stimulation, but not after median nerve stimulation. We suggest that painful trigeminal stimulation can induce an imbalance of the vestibular system in migraine patients and possibly explain their predisposition to vertigo. Our data require confirmation by other studies.

We evaluated whether type of response to the migraine-induction test with a nitroglycerin ointment applied to the frontotemporal head region could predict the efficacy of antimigraine therapy. Forty-two patients with migraine without aura underwent the test before and 2 months after antimigraine therapy. Two and 4 months after treatment withdrawal, most subjects with a negative response to the post-treatment test maintained treatment benefit, whereas benefit was lost in patients with an early onset migraine response.

We have compared the migraine-inducing effect of nitroglycerin ointment applied to the frontotemporal region of the head, which is innervated by the ophthalmic and maxillary divisions of the trigeminal nerve, with that of nitroglycerin applied to the chin (innervated by the mandibular division), the posterolateral region of the neck (innervated by the second and third cervical roots), the lateral surface of the proximal third of the forearm (innervated by the sixth cervical root), and the medial surface of the upper-arm region (second dorsal root). One hundred patients suffering from migraine without aura were randomly divided into five equal groups. Each group received an application of 5 mg nitroglycerin in 2% ointment on a preselected body area for 2 hours. Frontotemporal nitroglycerin induced a significantly greater number of early onset migraine attacks with respect to the arm and forearm regions. In all cases, nitroglycerin applied to the frontotemporal region resulted in subsequent migraine, whereas there was a significant number of negative trials with nitroglycerin applied to the neck, arm, and forearm vs the frontotemporal area. It, therefore, appears that the trigeminal nerve endings in the affected frontotemporal region are particularly sensitive to the migraine-inducing effect of the nitrate. This suggests a peripheral neurogenic hypothesis of migraine genesis.

The hypothesis that alpha-adrenergic receptor blockade accounts for the ability of ergotamine to stop migraine attacks was tested, in migraine patients, in an experimental migraine model based on nitroderivative- induced attacks. In a preliminary single blind, placebo controlled study, thymoxamine, a prevalently post-synaptic alpha adrenergic receptor antagonist, was able to abort migraine attack in 9 out of 10 patients, as opposed to 2 out of 10 by placebo (p0.005 Fisher's exact test). In a subsequent randomized, crossover, placebo controlled double blind study, the ability of a selective alpha-1 adrenergic receptor agonist, methoxamine, to block ergotamine antimigraine effect was studied. In 26 patients migraine was induced in two separate tests and then ergotamine was administered once after methoxamine pretreatment and once after placebo; methoxamine was significantly more effective than placebo in blocking antimigraine effect of ergotamine (p = 0.0055 Fisher's exact test). These results support the hypothesis that ergotamine alpha-1 adrenolytic properties may account for its antimigraine effect suggesting that this action takes place outside the blood-brain barrier, since methoxamine can cross it very poorly. Ergotamine target structure could be the trigeminal innervation of the extracranial and/or dural vessels.

Different classes of drugs are used in the pharmacological treatment of headache, both during migraine crisis and migraine prophylaxis. How these drugs exert their therapeutical effect in migraine is not clearly understood. Hypothetical mechanisms of action are discussed by the Authors in regard to the different pathogenetical events relevant to migraine. It is proposed that different pathological events can be modified by one drug and, conversely, one mechanism of action may be common to different drugs.

A case is presented of Dejerine-Sottas disease in a 12-year-old boy in which clinical signs made diagnosis of Friedreich's ataxia seem plausible. Based on marked slowing of motor conduction velocity, the sural nerve biopsy findings of a hypertrophic neuropathy with hypo- and demyelination of the nerve fibres, as well as the clinical history, the diagnosis of Dejerine-Sottas disease was made. ABR examination suggested involvement of brain stem at the roots and/or nuclei of the eighth cranial nerve, without involvement of higher structures.

A pharmacological trial has been carried out on 41 out-patients suffering from mixed headache. The prophylactic effect of a timed-release dihydroergotamine formulation was tested versus amitriptyline. Patients reported daily, on appropriate cards, the hours of headache and the degree of pain during the month before therapy and on the following two months of treatment. Whereas amitriptyline was found to be more effective than dihydroergotamine in reducing headache intensity, timed-release dihydroergotamine was found significantly more effective than amitriptyline in reducing attacks of “migraine” type. Les auteurs ont conduit une étude pharmacologique sur 41 patients souffrant de céphalée mixte. L'effet préventif de la dihydroergotamine à libération programmée a été comparé à celui de l'amitriptiline. Les patients ont quotidiennement enregistré, sur des fiches spéciales, les heures de céphalée et le degré d'intensité de la douleur au cours du mois précédant la thérapie et durant les deux mois de traitement. La dihydroergotamine à libération programmée s'est avérée de façon significative plus efficace que l'amitriptiline dans la réduction de la fréquence des attaques de type hémialgique. Gli autori hanno condotto uno studio farmacologico su 41 pazienti sofferenti di cefalea mista. L'effetto preventivo della diidroergotamina a liberazione programmata è stato paragonato a quello della amitriptilina. I pazienti hanno riportato, quotidianamente, su apposite schede, le ore di cefalea ed il grado di intensità del dolore nel mese precedente la terapia e durante i due mesi di trattamento. La diidroergotamina a liberazione programmata è risultata significativamente più efficace dell'amitriptilina nel ridurre la frequenza degli attacchi ti tipo emicranico.

The responses to work-test in ischemia (tourniquet technique), before and after I.V. injection of naloxone (2 mg) or saline, were investigated in healthy volunteers and patients suffering from various types of headache. The patients were examined during both painful and painless periods. We found that only the subjects suffering from migraine showed a significantly shortened pain tolerance at work-test in ischemia, after injection of naloxone, and only during painful periods. Psychogenic headache patients and migraine patients in painless periods showed responses during work-test similar to those in healthy volunteers, even after injection of naloxone. We believe that hyperalgesic effect of naloxone is due to involvement of b-endorphin systems only during organic pain.

Twenty common migraine patients received a one sided frontotemporal application of nitroglycerin (10 patients) or placebo ointment (10 patients) in a double blind study. Early onset migraine attacks were induced by nitroglycerin in seven out of 10 patients versus no patient in the placebo group. Subsequently 20 migraine patients, who developed an early onset attack with frontotemporal nitroglycerin, received the drug in a second induction test at other body areas. No early onset migraine was observed. Thus the migraine-inducing effect of nitroglycerin seems to depend on direct stimulation of the habitual site of pain, suggesting that the frontotemporal region is of crucial importance in the development of a migraine crisis. This is not consistent with a CNS origin of migraine attack.

Until the early 1990s, cluster headache (CH) was considered a sporadic disorder, with a prevalence of 69 per 100,000.1 The presence of CH in monozygotic twins2 and in first- and second-degree relatives3 suggested that genetic factors might be involved. Based on a mailed questionnaire, the prevalence of familial CH was 7%, and based on personal examination of alleged familial cases, it was 30%.3 A large epidemiologic study suggested autosomal dominant inheritance can be involved in some families.4 The current study describes a large kindred in which an autosomal recessive model could be involved. The pedigree (figure) includes four related families from the Naples area (southern Italy). The proband (IV-1), diagnosed in March 2000, referred other relatives possibly affected. All living members were interviewed by telephone, and all possibly affected members were evaluated by a neurologist experienced in CH. Clinical information about deceased individuals, obtained from their descendants, allowed us to exclude CH. Figure. Pedigree of a large kindred of four related families in which eight members …