Spectral linewidth narrowing by a narrow bandwidth squeezed vacuum in a cavity

The fluorescence spectrum of a strongly driven two-level atom located inside an optical cavity damped by a narrow-bandwidth squeezed vacuum is studied. We use a dressed atom model approach, first applied to squeezed vacuum problems by Yeoman and Barnett, to derive the master equation of the system and discuss the role of the cavity and the squeezed vacuum in the narrowing of the spectral lines and the population trapping effect. We find that in the presence of a single-mode cavity the effect of squeezing on the fluorescence spectrum is more evident in the linewidths of the Rabi sidebands rather than in the linewidth of the central component. Even in the absence of squeezing, the cavity can reduce the linewidth of the central component almost to zero, whereas the Rabi sidebands can be narrowed only to some finite value. In the presence of a two-mode cavity and a two-mode squeezed vacuum the signature of squeezing is evident in the linewidths of all spectral lines. We also establish that the narrowing of the spectral lines is very sensitive to the detuning of the driving field from the atomic resonance. Moreover, we find that the population trapping effect, predicted for the broadband squeezed vacuum case, may appear in a narrow-bandwidth case only if the input squeezed modes are perfectly matched to the cavity modes and if there is non-zero squeezing at the Rabi sidebands.

Quantum chaos in the atomic gravitational cavity

We report quantum chaos phenomena in the atomic gravitational cavity. We consider the reflection of cold atoms from a temporally modulated evanescent wave. In the globally chaotic regime, for small modulation, the squared energy distribution as a function of time demonstrates dynamical localization. However, for larger modulation delocalization occurs.

Movement-related potentials in Parkinson's disease - Motor imagery and movement preparation

Movement-related potentials (MRPs) associated with voluntary movements reflect cortical activity associated with processes Of movement preparation and movement execution. Early-stage pre-movement activity is reduced in amplitude in Parkinson's disease. However it is unclear whether this neurophysiological deficit relates to preparatory or execution-related activity, since previous studies have not been able to separate different functional components of MRPs. Motor imagery is thought to involve mainly processes of movement preparation, with reduced involvement of end-stage movement execution-related processes. Therefore, MRP components relating to movement preparation and execution may be examined separately by comparing MRPs associated with imagined and actual movements. In this study, MRPs were recorded from 14 subjects with Parkinson's disease and 10 age-matched control subjects while they performed a sequential button-pressing task, and while they imagined performance of the same task. Early-stage pre-movement activity was present in both Parkinson's disease patients and control subjects when they imagined movement, but was reduced in amplitude compared with that for actual movement. Movement execution-related components, arising predominantly from the primary motor cortex, were relatively unaffected in Parkinson's disease subjects. However motor preparatory processes, probably involving the supplementary motor area, were reduced in amplitude overall and abnormally prolonged, Indicating impaired termination following the motor response. Further this impaired termination of preparatory-phase activity was observed only in patients with more severe parkinsonian symptoms, and not in early-stage Parkinson's disease.

Cupped lesions of early onset dental erosion in young southeast Queensland adults

Background: Dental erosion manifests as cupped lesions on cusp apices and in fissures of teeth in patients from southeast Queensland referred with excessive tooth wear When found in young adults, these lesions may indicate early onset of active dental erosion. If the numbers and extent of cupped lesions increase with age, erosion may be a slow cumulative process. Methods: This cross-sectional study recorded the presence or absence and the relative sizes of cupped lesions from all cusps and occlusal fissures on premolar and permanent molar teeth from study models by image analysis. Type-specimens of cupped lesions were examined. Results: The Incidence by tooth reflected time in the mouth, post-tooth emergence. A linear increase in lesion number and size, with age, was found. However, cupped lesions occurred on mandibular first molar cusp apices as often, and attained greater extent, in adults under 27 years compared with older subjects. Conclusion: Marked differences were found between lesion number and size, between maxillary and mandibular molar sites that reflect differences in salivary protection against dental erosion. The significance of this study is that the mandibular first permanent molar indicates the age of onset and severity of dental erosion.

Becoming culturally inclusive: A perspective on personnel preparation

It can be said that some of the topics and ideas that command our interest or attention are autobiographical in origin. This paper subscribes to this category. In this paper, I present a perspective on preparing professional personnel, namely, educators, practitioners, teachers, student teachers, and researchers, for cultural inclusion. This perspective is drawn from my experiences as a former postgraduate student from a culturally diverse background preparing for a career in severe disabilities and as a university educator who is interested in ways to encourage professionals in the field to be more cognizant of the influence of their cultural backgrounds and the value of becoming culturally inclusive.