Vortex Motions in the Solar Atmosphere: Definitions, Theory, Observations, and Modelling.

Vortex flows, related to solar convective turbulent dynamics at granular scales and their interplay with magnetic fields within intergranular lanes, occur abundantly on the solar surface and in the atmosphere above. Their presence is revealed in high-resolution and high-cadence solar observations from the ground and from space and with state-of-the-art magnetoconvection simulations. Vortical flows exhibit complex characteristics and dynamics, excite a wide range of different waves, and couple different layers of the solar atmosphere, which facilitates the channeling and transfer of mass, momentum and energy from the solar surface up to the low corona. Here we provide a comprehensive review of documented research and new developments in theory, observations, and modelling of vortices over the past couple of decades after their observational discovery, including recent observations in H α , innovative detection techniques, diverse hydrostatic modelling of waves and forefront magnetohydrodynamic simulations incorporating effects of a non-ideal plasma. It is the first systematic overview of solar vortex flows at granular scales, a field with a plethora of names for phenomena that exhibit similarities and differences and often interconnect and rely on the same physics. With the advent of the 4-m Daniel K. Inouye Solar Telescope and the forthcoming European Solar Telescope, the ongoing Solar Orbiter mission, and the development of cutting-edge simulations, this review timely addresses the state-of-the-art on vortex flows and outlines both theoretical and observational future research directions.

On the effect of oscillatory phenomena on Stokes inversion results.

Stokes inversion codes are crucial in returning properties of the solar atmosphere, such as temperature and magnetic field strength. However, the success of such algorithms to return reliable values can be hindered by the presence of oscillatory phenomena within magnetic wave guides. Returning accurate parameters is crucial to both magnetohydrodynamics (MHD) studies and solar physics in general. Here, we employ a simulation featuring propagating MHD waves within a flux tube with a known driver and atmospheric parameters. We invert the Stokes profiles for the 6301 Å and 6302 Å line pair emergent from the simulations using the well-known Stokes Inversions from Response functions code to see if the atmospheric parameters can be returned for typical spatial resolutions at ground-based observatories. The inversions return synthetic spectra comparable to the original input spectra, even with asymmetries introduced in the spectra from wave propagation in the atmosphere. The output models from the inversions match closely to the simulations in temperature, line-of-sight magnetic field and line-of-sight velocity within typical formation heights of the inverted lines. Deviations from the simulations are seen away from these height regions. The inversions results are less accurate during passage of the waves within the line formation region. The original wave period could be recovered from the atmosphere output by the inversions, with empirical mode decomposition performing better than the wavelet approach in this task. This article is part of the Theo Murphy meeting issue 'High-resolution wave dynamics in the lower solar atmosphere'.

Acoustic-gravity wave propagation characteristics in three-dimensional radiation hydrodynamic simulations of the solar atmosphere.

There has been tremendous progress in the degree of realism of three-dimensional radiation magneto-hydrodynamic simulations of the solar atmosphere in the past decades. Four of the most frequently used numerical codes are Bifrost, CO5BOLD, MANCHA3D and MURaM. Here we test and compare the wave propagation characteristics in model runs from these four codes by measuring the dispersion relation of acoustic-gravity waves at various heights. We find considerable differences between the various models. The height dependence of wave power, in particular of high-frequency waves, varies by up to two orders of magnitude between the models, and the phase difference spectra of several models show unexpected features, including ±180° phase jumps. This article is part of the Theo Murphy meeting issue 'High-resolution wave dynamics in the lower solar atmosphere'.

On the influence of magnetic topology on the propagation of internal gravity waves in the solar atmosphere.

The solar surface is a continuous source of internal gravity waves (IGWs). IGWs are believed to supply the bulk of the wave energy for the lower solar atmosphere, but their existence and role for the energy balance of the upper layers is still unclear, largely due to the lack of knowledge about the influence of the Sun's magnetic fields on their propagation. In this work, we look at naturally excited IGWs in realistic models of the solar atmosphere and study the effect of different magnetic field topographies on their propagation. We carry out radiation-magnetohydrodynamic simulations of a magnetic field free and two magnetic models-one with an initial, homogeneous, vertical field of 100 G magnetic flux density and one with an initial horizontal field of 100 G flux density. The propagation properties of IGWs are studied by examining the phase-difference and coherence spectra in the kh - ω diagnostic diagram. We find that IGWs in the upper solar atmosphere show upward propagation in the model with predominantly horizontal field similar to the model without magnetic field. In contrast to that the model with predominantly vertical fields show downward propagation. This crucial difference in the propagation direction is also revealed in the difference in energy transported by waves for heights below 0.8 Mm. Higher up, the propagation properties show a peculiar behaviour, which require further study. Our analysis suggests that IGWs may play a significant role in the heating of the chromospheric layers of the internetwork region where horizontal fields are thought to be prevalent. This article is part of the Theo Murphy meeting issue 'High-resolution wave dynamics in the lower solar atmosphere'.

Influence of the cortical electrical activity level during general anaesthesia on the severity of immediate postoperative pain in the morbidly obese.

BACKGROUND: The objective of anaesthesia is to provide hypnosis, analgesia and adequate conditions during surgery. It is difficult to establish the appropriate dose of general anaesthetic drugs in the morbidly obese patient. Moreover, there are conflicting data concerning adequate anaesthesia levels and the severity of postoperative pain. The aim of this study was to investigate the relationship between the spectral edge frequency (SEF) during general anaesthesia and the severity of immediate postoperative pain following gastric banding surgery in morbidly obese patients. METHODS: Seventy-one ASA 2 morbidly obese patients (BMI > 35%) undergoing elective laparoscopic gastric banding procedure were recruited for this study. Anaesthesia consisted of midazolam, fentanyl and thiopental for induction, vecuronium for muscle relaxation, N2O and isoflurane with additional fentanyl administrations, according to the clinical judgement of the anaesthesiologist, for maintenance. Continuous SEF monitoring was added to the standard monitors (SpO2, ETCO2, ECG, NIBP, O2 and isoflurane concentration), but the EEG monitor screen was hidden from the anaesthesiologist's sight. SEF postoperative analysis divided the patients into two groups: group 1, SEF-recommended target range of 8-12 Hz, more than 80% of the surgical time; and group 2, SEF-recommended target range of 8-12 Hz, less than 80% of the surgery duration. Pain intensity was assessed in the post anaesthesia care unit using a standard visual analogue scale (VAS) of 10 cm, when patients were awake enough to correct a deliberately given wrong own telephone or ID number. Intravenous morphine was administered for postoperative analgesia in 2-mg increments, every 3-4 min, until the patient felt comfortable. A recovery room nurse unaware of the SEF range recorded during surgery registered pain severity and morphine requirements. RESULTS: The end-tidal isoflurane concentration was significantly higher in group 1 than in group 2 (0.83 vs. 0.7 P = 0.016). The intensity of pain at admission into the recovery room and at discharge was significantly lower in group 1 than in group 2 (VAS 6.1 vs. 6.9-P = 0.0049, and 3.9 vs. 4.2-P = 0.00478, respectively). CONCLUSIONS: Keeping the SEF range between 8 and 12 Hz during anaesthesia for laparoscopic gastric banding for morbid obesity, both the immediate post operative pain intensity and morphine requirement, are significantly reduced.

Vascular dementia versus dementia of Alzheimer's type: do they have differential effects on caregivers' burden?

OBJECTIVES: We investigated homecare patients with dementia of Alzheimer's type (DAT; n = 36) or vascular dementia (VD; n = 36) and their care-providing relatives regarding clinical and psychosocial variables to determine whether DAT and VD impose different burdens on caregivers. METHOD: All patients were diagnosed according to ICD-10 criteria. The diagnoses were confirmed by internal medical, clinical-neurological, and psychiatric parameters. The severity of the dementias was graded according to the Global Deterioration Scale (GDS). Caregiving relatives responded to the Behavioral Pathology in Alzheimer's Disease Rating Scale (BAD), the Blessed Dementia Scale (BDS), and the Screen for Caregiver Burden (SCB). RESULTS: Analyses revealed that caregivers' burden (SCB), disease symptoms and personality changes of patients (BAD), and the patients' inability to cope with everyday tasks (BDS) were sharply higher for DAT than for VD patients in the group with severe dementia. Concerning patients with mild or moderately severe disease, scores in the DAT group were similar or lower than those in the VD group. CONCLUSION: In early stages, VD patients impose a greater burden on relatives than do patients with DAT. In severe stages this relationship undergoes a reversal, with relatives of DAT patients experiencing the burden more adversely than those of VD patients. The differences in the onset and course characteristics, as well as the specific differences between these two types of dementia with respect to caregiver burden factors, call for their diagnostic separation and the development of specific homecare support systems for family caregivers.

Factors affecting the utilization of homecare supports by caregiving relatives of Alzheimer patients.

Thirty-six homecare patients with dementia of Alzheimer type (DAT) and their caregiving relatives were studied to determine the factors influencing their use or nonuse of available medical, institutional, instrumental, and legal supports. The rate of utilization of homecare support was found to be surprisingly low. Only when the burden of providing care had become intolerable did relatives resort to homecare support (homecare allowance, counseling, outpatient services, etc.). The main reason for the low utilization was poor knowledge regarding the availability of homecare supports. Since all of the DAT patients were under the care of a family doctor, this information deficit could best be overcome by improved counseling from personal physicians.