Biomedical subjects
Publications and source records attributed to A Carollo.
We calculate the geometric phase of a spin-1/2 system driven by one and two mode quantum fields subject to decoherence. Using the quantum jump approach, we show that the corrections to the phase in the no-jump trajectory are different when considering adiabatic and nonadiabatic evolutions. We discuss the implications of our results from both fundamental as well as quantum computational perspectives.
We calculate the geometric phase associated with the evolution of a system subjected to decoherence through a quantum-jump approach. The method is general and can be applied to many different physical systems. As examples, two main sources of decoherence are considered: dephasing and spontaneous decay. We show that the geometric phase is completely insensitive to the former, i.e., it is independent of the number of jumps determined by the dephasing operator.
We calculate the Berry phase of a spin-1/2 particle in a magnetic field considering the quantum nature of the field. The phase reduces to the standard Berry phase in the semiclassical limit and the eigenstate of the particle acquires a phase in the vacuum. We also show how to generate a vacuum induced Berry phase considering two quantized modes of the field which has an interesting physical interpretation.
Environmental stressors can substantially affect the adaptive response of rats to novelty in a sexually dimorphic manner. Gender-related differences are also observed in neurochemical and behavioural patterns of adult rats following prenatal exposure to diazepam (DZ). In the present study the behavioural reactivity to novelty is investigated in open field (OF) and in acoustic startle reflex (ASR) tests, in non handled (NH), short-lasting handled (SLH) and long-lasting handled (LLH) adult male and female rats prenatally exposed to DZ. A single daily s.c. injection of DZ (1.5 mg/kg) over gestation days 14-20 decreases GABA/BDZ receptor function in both sexes, as shown by the decreased electrographic hippocampal response to DZ and the increased response to picrotoxin, after intra-locus coeruleus injection of the two compounds. In OF NH DZ-exposed males display a lower total distance travelled (TDT), a higher rearing frequency (RF) and a greater number of transitions in the centre of the arena (CNT) compared to NH rats prenatally exposed to vehicle. Conversely, NH DZ-exposed females show slight changes in TDT and RF and a greater reduction in CNT and in the amount of time spent in the centre of the arena (CAT). These effects are associated with an increase in the peak amplitude of the ASR in both sexes. Short-lasting handling slightly influences DZ-evoked effects in animals of both sexes. In DZ-exposed males long-lasting handling attenuates the reduction in TDT and the enhancement in RF, prevents the increase in CNT and reduces the peak amplitude of ASR. In DZ-exposed females, long-lasting handling increases TDT and RF, induces a lower avoidance of the centre of the arena, and does not modify the peak amplitude of ASR, when compared to controls. These findings indicate that prenatal exposure to DZ differently affects behavioural reactivity in adult male and female rats, and suggest that a long-lasting handling is able to attenuate some behavioural deficits induced by prenatal DZ exposure.
We describe a system for controlling postoperative pain, a phenomenon that is difficult to treat by conventional control methods due to interpatient variability, interferences, non-linearity and the lack of a plausible, well-defined mathematical model. The system consists of two phases. In Phase 1 a closed-loop fuzzy controller implementing a suitable control strategy brings the patient to a zero-pain state. In Phase 2, an open-loop computer-assisted continuous infusion controller maintains a constant concentration of the analgesic (alfentanil) in plasma, subject to an upper safety limit on infusion rate; the set-point of this controller is periodically revised (either maintained or reduced) on the basis of feedback on the duration of zero pain (set-point reduction is necessary because the open-loop system has no means of knowing whether analgesic is accumulating in the patient). Pain is quantified by the patient on a numerical scale of 1 to 10 at 1.5-min intervals during Phase 1 and 9-min intervals during Phase 2. In simulation trials in which a fixed approximate model was used for the effect of sedation on pain while the pharmacokinetics of alfentanil were varied from one simulated patient to another, zero pain was achieved in under 15 min with minimal overshoot in plasma drug concentration and was maintained, with only minor deviation, by means of low drug concentrations.
The 20% of male 5-6 month-old Wistar rats SM prove to be natural killers. A four-month long insulation of "surely non-killer" rats has not allowed to notice a mouse-killing behaviour in any animal. The total bilateral removal of olfactory bulbs in "non-killer rats" causes a "mouse-killing behaviour" in all the animal 24 hours after the operation, but with a latency of response that has proved different in the various rats. Precisely, while 24 hours and 15 days after the bulb operation the rats can be distinguished into "rapid killers" and "slow killers", after 30 days all the animals become "rapid killers" with a remarkably shortened period of mouse-killing latency (1 - 60 seconds).
An investigation was made of the effect of thermic stress on the somatic rage reaction and on rapid circling turns in cats awake and free to move in a behavioural cage. An increase in room temperature had a two-phase effect on the excitability of the nervous structures stimulated that is able to evoke the somatic rage reaction and rapid circling turns. The first phase, at room temperature 25 degrees-30 degrees C, was characterized by hypoexcitability; the second phase, appearing after longer periods of exposure and at temperatures above 30 degrees C, was characterized by the onset panting, hyperexcitability of the nervous structures stimulated and then by lowering of the somatic rage reaction threshold and a very significant increase in the number of circling turns. Experimentation on the action of cold external temperature on the excitability of structures involved in evoking the somatic rage reaction and rapid circling turns indicated an increase in their excitability, corresponding to an increase in spontaneous and evoked somatic motor activity.
We examined first the behavior of a single animal (Macacus Rhesus), partially free to move on a Brady chair, before and after direct electrical stimulation of the amygdala and the hippocampus; then the social behavior of two animals, completely free to move in a large behavioral cage, before and after stimulation, by radio, of the amygdala. Certain ventromedial areas of the amygdala have a short and long term inhibitory effect on feeding and social behavior and the hippocampus has a short and long term facilitating effect on feeding behavior, especially during the after discharge.
OBJECTIVE: To apply a fuzzy logic expert control system for the treatment of postoperative pain in a clinical setting. MATERIAL AND METHODS: A system was designed consisting of a perfusion pump guided by a fuzzy logic computer interface to regulate the perfusion of alfentanil in accordance with the patient's pain response. The system was also equipped with a safety device that halted perfusion in case of desaturation, bradypnea or heart rate or blood pressure variations greater than 25%. The system was used in the first 90 minutes after surgery in a patient who underwent bilateral saphenectomy. RESULTS: All system functions worked properly, maintaining the target analgesic values (visual analog scale < or = 2) 77% of the time. CONCLUSION: It is possible to use fuzzy logic to obtain adequate treatment of postoperative pain.