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The impact of meridional winds on the onset and evolution of equatorial plasma bubbles (EPBs) is reviewed. The conventional wisdom had been that transequatorial meridional winds have a stabilizing effect on the development of EPBs during equatorial spread F (ESF). However, this result is based on a uniform transequatorial meridional wind. Subsequently, it was demonstrated that a non-uniform meridional wind could have a stabilizing or destabilizing effect on EPB formation depending on the direction of wind gradient. The destabilization of EPBs associated with equatorward flowing meridional winds has recently been investigated during a midnight temperature maximum event and a geomagnetic storm. Although the neutral wind is a direct destabilizing influence in these cases, the large decrease in the Pedersen conductance caused by meridional equatorward winds is the primary reason for the large increase in the growth rate of the generalized Rayleigh-Taylor instability. We review the theoretical and modeling studies of this topic as well as observational studies that have been made to assess the relationship between meridional winds and ESF. [ABSTRACT FROM AUTHOR]

Celestial phenomena such as solar eclipses disrupt the ionosphere's inherent photochemical, dynamic, and electrodynamic processes and can be viewed as a natural experiment that provides a unique opportunity to study ionospheric perturbations. We investigate the spatiotemporal ionospheric response induced by the 14 October 2023 annular eclipse using ground‐based Global Navigation Satellite System (GNSS) receivers located over the continental region of North and South America. The largest total electron content (TEC) change (∼22 TECU decrease) is observed over the path of the eclipse at around 16°–18°N which lies just before the greatest eclipse location. However, the percentage change in TEC here is ∼44% (of the background value), which is less than that observed at midlatitudes around 30°–35°N (∼18.7 TECU, ∼50%). We observed a latitudinal dependency of TEC variation and time delay in ionospheric response to the eclipse with midlatitudes experiencing greater TEC changes and longer time delays compared to low‐latitude and equatorial regions. The SAMI3 model used to simulate the impact of the eclipse, captures the large decrease in VTEC along the eclipse path. Interestingly, increases in the TEC are also observed in several GNSS sites and it varied from 4.5 to 6.5 TECU in the Northern Hemisphere and 7 to 12 TECU in the Southern Hemisphere. The SAMI3 model results also show an enhancement in TEC but significantly less than that observed. Moreover, the SAMI3 model simulations for individual GNSS site coordinates within the conjugate regions failed to predict accurately, the TEC enhancement recorded by the GNSS sites. Key Points: The total electron content (TEC) depletion and time delay in ionospheric response to the solar eclipse exhibited a latitudinal dependency within the eclipse regionSAMI3 model accurately simulated the observed TEC drop in the eclipse region but underpredicted the TEC enhancement in the conjugate regionsTEC increase in the Southern Hemisphere conjugate region is attributed to uplifted plasma resulting from an enhanced E × B drift velocity [ABSTRACT FROM AUTHOR]

The paper presents the effects of the storm‐time prompt penetration electric fields (PPEF) and traveling atmospheric disturbances (TADs) on the total electron content (TEC), foF2 and hmF2 in the American sector (north and south) during the geomagnetic storm on 23–24 April 2023. The data show a poleward shift of the Equatorial Ionization Anomaly (EIA) crests to 18°N and 20°S in the evening of 23 April (attributed to eastward PPEF) and the EIA crests remaining almost in the same latitudes after the PPEF reversed westward. The thermospheric neutral wind velocity, foF2, hmF2, and TEC variations show that TADs from the northern and southern high latitudes propagating equatorward and crossing the equator after midnight on 23 April. The meridional keograms of ΔTEC show the TAD structures in the north/south propagated with phase velocity 470/485 m/s, wave length 4,095/4,016 km and period 2.42/2.30 hr, respectively. The interactions of the TADs also appear to modify the wind velocities in low latitudes. The eastward PPEF and equatorward TADs also favored the development of a clear/not so clear F3 layer in northern/southern regions of the equator. Plain Language Summary: The thermosphere‐ionosphere‐magnetosphere system is largely affected during events of geomagnetic storms. Its dynamics, mainly in the ionized environment, may impact modern lives by degradations in the satellite signals affecting, for example, all applications involving Global Navigation Satellite System. The thermosphere and ionosphere responses to the large geomagnetic storm of 23–24 April 2023 are analyzed here and the main discoveries are the unexpected spatial plasma density distribution over Boa Vista (MLat ≈ 8°N) due to resulting effects of a disturbed eastward electric field and traveling atmospheric disturbance (TAD). The interactions/interferences of TADs were able to explain the unexpected moment of the peak in thermospheric neutral wind speed measurements over the equatorial station, as well as all variations in ionospheric parameters (foF2, hmF2, and total electron content) recorded in pairs by seven Digisondes and GNSS receivers spread across Brazil. Key Points: Interactions of traveling atmospheric disturbances (TADs) cause unexpected thermospheric neutral wind speeds in the American equatorial and low‐latitude sectorsThe effects resulting from a disturbed electric field and TADs were able to produce anomalous electron density distribution at low latitudesThe variations in the ionospheric observational measurements recorded around 4 UT in Brazil on 24 April 2023 were explained by the passages of TADs [ABSTRACT FROM AUTHOR]

We report results from a global simulation of the September 2017 geomagnetic storm. The global model comprises the ionospheric code SAMI3 and the atmosphere/thermosphere code WACCM‐X. We show that a train of large‐scale EPBs form in the Pacific sector during the storm recovery phase on 8 September 2017. The EPBs are associated with storm‐induced modification of the zonal and meridional winds. These changes lead to an eastward electric field which in turn causes an upward E × B drift in the post‐midnight sector. A large decrease in the Pedersen conductance caused by meridional equatorward winds leads to an increase in the growth rate of the generalized Rayleigh‐Taylor instability that causes EPBs to develop. Interestingly, several EPBs reach altitudes above 3,000 km. Plain Language Summary: The uppermost layer of the atmosphere, the thermosphere, is heated at high latitudes during geomagnetic storms by energy inputs from the magnetosphere. This heating significantly modulates the thermosphere winds on a global scale that results in the modification of the electrodynamics of the ionosphere at low‐ to mid‐latitudes. Using the coupled SAMI3/WACCM‐X model, we show that equatorial plasma bubbles (EPBs) (large‐scale depletions of the electron density in the ionosphere) can develop because of these stormtime changes to the winds and electric field. This is significant because EPBs can adversely impact space‐based communication and navigation systems by degrading the reception of electromagnetic signals that pass through them. Key Points: Stormtime modulation of the zonal and meridional winds increase the eastward electric field at night in the Pacific sectorEquatorial plasma bubbles subsequently develop in the Pacific sector during the September 2017 storm on September 8Several equatorial plasma bubbles rise to over 3,000 km with upward velocities exceeding 300 m/s [ABSTRACT FROM AUTHOR]

Purpose: To compare the outcomes of the Tecnis Eyhance ICB00 IOL, designed to enhance intermediate vision, to a conventional Tecnis Monofocal ZCB00 IOL. Methods: This retrospective analysis compared two cohorts of patients undergoing lens replacement surgery with bilateral implantation of the Tecnis ICB00 or the Tecnis ZCB00 IOL (383 patients in each group). Monocular and binocular uncorrected distance (UDVA), intermediate (UIVA; 66cm), and near (UNVA; 40cm) visual acuities, refractive predictability, and patient-reported outcomes were compared. A sub-analysis of patients with the Eyhance IOL was performed to compare patients who achieved bilateral emmetropia to those with mini-monovision. One-month postoperative outcomes were analyzed. Results: Both groups had comparable UDVA outcomes. On average, both monocular and binocular UIVAs were approximately one Snellen line better in patients implanted with Eyhance IOL (monocular UIVA: ICB00 0.23 ± 0.18 logMAR, ZCB00 0.33 ± 0.19 logMAR; binocular UIVA: ICB00 0.18 ± 0.18 logMAR, ZCB00 0.26 ± 0.20 logMAR, p < 0.01). Likewise, the mean UNVA was also one Snellen line better with the ICB00 model (monocular UNVA: ICB00 0.51 ± 0.20 logMAR, ZCB00 0.61 ± 0.18 logMAR; binocular UNVA: ICB00 0.42 ± 0.19 logMAR, ZCB00 0.51 ± 0.22 logMAR, p < 0.01). There was no difference between the two groups in overall satisfaction or visual phenomena. A subgroup of patients who achieved mini-monovision with Eyhance IOL had, on average, one Snellen line better UIVA and UNVA compared to patients with bilateral emmetropia. Conclusion: Patients receiving the enhanced monofocal IOL had better intermediate and near vision compared to those receiving the conventional monofocal IOL, with similar levels of patient-reported photic phenomena in both groups. [ABSTRACT FROM AUTHOR]

Purely data-driven ionospheric modeling fails to adequately obey fundamental physical laws. To overcome this shortcoming, we propose a novel ionospheric inversion model, Physics-Informed Neural Network based on fully physical models SAMI3 (PINN-SAMI3). The model incorporates the governing equations of the ionospheric physical model SAMI3 into the neural network to reconstruct the temporal-spatial distribution of ionospheric plasma parameters. The objective of this study is to investigate the feasibility of integrating physical models with machine learning for ionospheric modeling. The PINN-SAMI3 framework enforces physical laws through the multiple ion species of continuity, momentum, temperature equations in the magnetic dipole coordinate system. The simulation results show that if sparse ion densities are used as training data, it is possible to retrieve ionospheric electron densities, ion velocities and ion temperatures, respectively. The optimal physical constraints have been also investigated for different inversion quantities. Furthermore, the impact of incorporating E x B velocity terms on inversion results during the periods of ionospheric calm and geomagnetic storm is analyzed. The PINN-SAMI3 achieves good inversion results even using sparse data in comparison to the traditional artificial neural networks (ANN). The framework will contribute to advance the future space weather prediction capability with artificial intelligence (AI). [ABSTRACT FROM AUTHOR]

New, open access tools have been developed to validate ionospheric models in terms of technologically relevant metrics. These are ionospheric errors on GPS 3D position, HF ham radio communications, and peak F‐region density. To demonstrate these tools, we have used output from Sami is Another Model of the Ionosphere (SAMI3) driven by high‐latitude electric potentials derived from Active Magnetosphere and Planetary Electrodynamics Response Experiment, covering the first available month of operation using Iridium‐NEXT data (March 2019). Output of this model is now available for visualization and download via https://sami3.jhuapl.edu. The GPS test indicates SAMI3 reduces ionospheric errors on 3D position solutions from 1.9 m with no model to 1.6 m on average (maximum error: 14.2 m without correction, 13.9 m with correction). SAMI3 predicts 55.5% of reported amateur radio links between 2–30 MHz and 500–2,000 km. Autoscaled and then machine learning "cleaned" Digisonde NmF2 data indicate a 1.0 × 1011 el. m3 median positive bias in SAMI3 (equivalent to a 27% overestimation). The positive NmF2 bias is largest during the daytime, which may explain the relatively good performance in predicting HF links then. The underlying data sources and software used here are publicly available, so that interested groups may apply these tests to other models and time intervals. Plain Language Summary: Multiple research groups are developing models of the ionosphere to address effects on technology that depends on radio signal propagation. Here we present tests of these models that capture the model performance as it relates to some relevant applications. These are GPS position, long‐distance HF communication and ionospheric critical frequency (which is proportional to the square root of the peak ionospheric density). All the data sets, testing code and model output used are made available in the public domain for reuse and development. For the test of critical frequency, we use machine learning to "clean up" the input data, removing errors introduced in the data generation process. Key Points: New, open access tools developed to validate ionospheric modelsMetrics are GPS position, HF communications, and critical frequency/NmF2Machine learning applied to "clean up" auto‐scaled ionosonde data, removing 94% of badly scaled NmF2 values [ABSTRACT FROM AUTHOR]

Purpose: To compare refractive, visual, and patient-reported outcomes associated with a 1st generation wavefront-guided (WFG) treatment with those associated with a 3rd generation WFG treatment.Patients and Methods: This retrospective study included patients who underwent femtosecond laser-assisted in situ keratomileusis (LASIK) for myopia/myopic astigmatism. Two random stratified samples of patients who underwent either 1stgeneration (WaveScan, Johnson & Johnson Vision, Santa Ana, CA) or 3rd generation (iDesign 2.0, Johnson & Johnson Vision, Santa Ana, CA) treatment matched on preoperative refraction were compared (4290 eyes of 2145 patients in each group). One-month postoperative visual, refractive, and patient-reported outcomes were analyzed. Refractive and monocular visual acuity analyses were performed using one random eye of each patient.Results: The percentage of eyes achieving 20/20 or better uncorrected vision was 91.3% (1958/2145) in the 1st generation group and 95.9% (2056/2145) in the 3rd generation group (p< 0.01). Binocularly, the percentage of patients with 20/20 or better UDVA was 97.0% (2080/2145) and 99.2% (2127/2145) in the 1st and 3rd generation groups, respectively (p< 0.01). The mean postoperative MSE was − 0.01 ± 0.33 D in the 1st generation group and +0.19 ± 0.33 D in the 3rd generation group (p< 0.01). Postoperative refractive astigmatism had a mean value of − 0.20 ± 0.26 D and − 0.18 ± 0.24 D in the 1st and 3rd generation groups, respectively (p< 0.01). The mean correction index of refractive astigmatism was 1.09 ± 0.53 in the 1st generation group and 1.02 ± 0.38 in the 3rd generation group, p< 0.01. The overall percentage of patients satisfied with vision was 92.8% (1991/2145 patients) in the 1st generation group and 97.3% (2087/2145 patients) in the 3rd generation group (p< 0.01).Conclusion: For the majority of postoperative variables, there were significant differences between 1st and 3rd generation treatments. The 3rd generation treatments had better visual acuity outcomes and higher patient satisfaction. [ABSTRACT FROM AUTHOR]

We simulate the gravity waves (GWs) and traveling ionospheric disturbances (TIDs) created by the Hunga Tonga‐Hunga Ha'apai (hereafter "Tonga") volcanic eruption on 15 January 2022 at ∼04:15 UT. We calculate the primary GWs and forces/heatings generated where they dissipate with MESORAC, the secondary GWs with HIAMCM, and the TIDs with SAMI3. We find that medium and large‐scale TIDs (MSTIDs and LSTIDs) are induced by the secondary GWs, with horizontal phase speeds cH ≃ 100–750 m/s, horizontal wavelengths λH ≃ 600–6,000 km, and ground‐based periods τr ≃ 30 min to 3 hr. The LSTID amplitudes over New Zealand are ≃2–3 TECU, but decrease sharply ≃ 5,000 km from Tonga. The LSTID amplitudes are extremely small over Australia and South Africa because body forces create highly asymmetric GW fields and the GWs propagate perpendicular to the magnetic field there. We analyze the TIDs from SAMI3 and find that a 30 min detrend window eliminates the fastest far‐field LSTIDs. We analyze the GPS/TEC via detrending with 2–3 hr windows, and find that the fastest LSTIDs reach the US and South America at ∼8:30–9:00 UT with cH ≃ 680 m/s, λH ≃ 3,400 km, and τr ≃ 83 min, in good agreement with model results. We find good agreement between modeled and observed TIDs over New Zealand, Australia, Hawaii, Japan and Norway. The observed F‐peak height, hmF2, drops by ≃ 110–140 km over the western US with a 2.8 hr periodicity from 8:00 to 13:00 UT. We show that the Lamb waves (LWs) observed by AIRS with λH = 380 km have amplitudes that are ≃ 2.3% that of the primary GWs at z ≃ 110 km. We conclude that the observed TIDs can be fully explained by secondary GWs rather than by "leaked" LWs. Plain Language Summary: Gravity waves (GWs) are created by various processes, such as volcanic eruptions. A breaking GW imparts momentum and energy to the atmosphere, which creates secondary GWs. Traveling ionospheric disturbances (TIDs) are created by GWs through collisions between neutral and ion molecules. We simulate the GWs and TIDs created by the Tonga eruption on 15 January 2022. We find that medium and large‐scale TIDs (MSTIDs and LSTIDs) are induced by the secondary GWs. These TIDs propagate globally, and have speeds of 100–750 m/s and horizontal scales of hundreds to thousands of km. The fastest TIDs reach the United States and South America at ∼8:30–9:00 UT; these TIDs have large scales and large periods, in agreement with observations. These LSTIDs can only be seen if they are not "detrended out" when processing the ionospheric data. Previous studies eliminated these LSTIDs by restricting their detrend windows, and then incorrectly suggested that Lamb waves were responsible for the TIDs they observed. Using longer detrend windows, we find good agreement between the modeled and observed TIDs. We find that the observed TIDs can be fully explained by secondary GWs, rather than by the leakage of Lamb waves into GWs. Key Points: Globally‐propagating concentric TIDs are induced by secondary GWs from the Tonga eruption with cH = 100−750 m/s and τr = 30 min to 3 hrThe fastest LSTIDs from Tonga in the far field are eliminated when detrending SAMI3 and GPS/TEC data with a 30 min windowThe fastest modeled LSTIDs from Tonga reach the US and South America at 8:30‐9:00 UT with cH = 600 m/s, in good agreement with data [ABSTRACT FROM AUTHOR]

To investigate the characteristics of ocular surface sensations and corneal sensitivity during the interblink interval before and after tear supplementation in dry eye patients.Twenty subjects (41.88±14.37 years) with dry eye symptoms were included in the dry eye group. Fourteen subjects (39.13±11.27 years) without any clinical signs and/or symptoms of dry eye were included in the control group. Tear film dynamics was assessed by non-invasive tear film breakup time (NI-BUT) in parallel with continuous recordings of ocular sensations during forced blinking. Corneal sensitivity to selective stimulation of corneal mechano-, cold and chemical receptors was assessed using a gas esthesiometer. All the measurements were made before and 5 min after saline and hydroxypropyl-guar (HP-guar) drops.In dry eye patients the intensity of irritation increased rapidly after the last blink during forced blinking, while in controls there was no alteration in the intensity during the first 10 sec followed by an exponential increase. Irritation scores were significantly higher in dry eye patients throughout the entire interblink interval compared to controls (p0.05).Ocular surface irritation responses due to tear film drying are considerably increased in dry eye patients compared to normal subjects. Although tear supplementation improves the protective tear film layer, and thus reduce unpleasant sensory responses, the rapid rise in discomfort is still maintained and might be responsible for the remaining complaints of dry eye patients despite the treatment.

Dry eye complaints are ranked as the most frequent symptoms of patients visiting ophthalmologists. Conjunctivochalasis is a common dry eye disorder, which can cause an unstable tear film and ocular discomfort. The severe conjunctivochalasis characterized by high LId-Parallel COnjunctival Folds (LIPCOF) degree usually requires surgical intervention, where a conservative therapy would be highly desirable. Here we examined the efficacy of a preservative-free, inorganic salt-free unit-dose artificial tear, called Conheal containing isotonic glycerol and 0.015% sodium hyaluronate in a prospective, unmasked, self-controlled study involving 20 patients. The regular use of the glycerol/hyaluronate artificial tear in three months caused a significant improvement in the recorded parameters. Conjunctivochalasis decreased from a mean LIPCOF degree of 2.9 ± 0.4 on both eyes to 1.4 ± 0.6 on the right (median decrease of -2 points, 95% CI from -2.0 to -1.0), and to 1.4 ± 0.7 on the left eye (median decrease of -1 points, 95% CI from -2.0 to -1.0) (p

To investigate corneal sensitivity to selective mechanical, chemical, and thermal stimulation and to evaluate their relation to dry eye symptoms in patients with keratoconus.Corneal sensitivity to mechanical, chemical, and thermal thresholds were determined using a gas esthesiometer in 19 patients with keratoconus (KC group) and in 20 age-matched healthy subjects (control group). Tear film dynamics was assessed by Schirmer I test and by the non-invasive tear film breakup time (NI-BUT). All eyes were examined with a rotating Scheimpflug camera to assess keratoconus severity.KC patients had significatly decreased tear secretion and significantly higher ocular surface disease index (OSDI) scores compared to controls (5.3±2.2 vs. 13.2±2.0 mm and 26.8±15.8 vs. 8.1±2.3; p0.05). The mean threshold for selective mechanical (KC: 139.2±25.8 vs. control: 109.1±24.0 ml/min), chemical (KC: 39.4±3.9 vs. control: 35.2±1.9%CO2), heat (KC: 0.91±0.32 vs. control: 0.54±0.26 Δ°C) and cold (KC: 1.28±0.27 vs. control: 0.98±0.25 Δ°C) stimulation in the KC patients were significantly higher than in the control subjects (p0.05), whereas in the control subjects both mechanical (r = 0.52, p = 0.02), chemical (r = 0.47, p = 0.04), heat (r = 0.26, p = 0.04) and cold threshold (r = 0.40, p = 0.03) increased with age. In the KC group, neither corneal thickness nor tear flow, NI-BUT or OSDI correlated significantly with mechanical, chemical, heat or cold thresholds (p>0.05 for all variables).Corneal sensitivity to different types of stimuli is decreased in patients with keratoconus independently of age and disease severity. The reduction of the sensory input from corneal nerves may contribute to the onset of unpleasant sensations in these patients and might lead to the impaired tear film dynamics.

The energy deposition from ring current ions into the high density "cold" plasma of the ionosphere and plasmasphere is analyzed, based on a Comprehensive Inner Magnetosphere‐Ionosphere simulation of the 2015 October 7 storm. In addition, the Naval Research Laboratory Sami3 is Also a Model of the Ionosphere ionosphere/plasmasphere code is used to simulate the effect of Coulomb‐collision heating of plasmasphere and ionosphere electrons by ring current ions. We find that, during stormtime peaks in the Dst index, energy is deposited at altitudes as low as 100 km. Heating along the entirety of any given field line, both in the ionosphere and plasmasphere, contributes to increased temperatures in the ionosphere F layer and inner magnetosphere and to subsequent cold O+ outflows. However, relative to the heating of the plasmasphere, the direct heating of the ionosphere by ring current ions produces only small effects. Qualitative model‐data agreement on the N+/O+ density ratio is consistent with the hypothesis that these outflows are driven by thermal forcing. Plain Language Summary: When the solar wind encounters Earth's magnetosphere, a geomagnetic storm can result. These storms generate a "ring current" in the inner magnetosphere. This current, carried by high energy oxygen and hydrogen ions, overlaps with the plasmasphere, a background plasma (mainly hydrogen ions) held in place by Earth's geomagnetic field. We find that the ring current also overlaps with the near‐Earth ionosphere. In previous work, we showed that, when the background plasma is heated by the ring current, oxygen ions flow upward along the geomagnetic field, producing a "heavy ion" population (the O+ shell) that has been observed. We now focus on the direct heating of the ionosphere by the ring current, versus the indirect effect where energy deposited into the higher altitude plasmasphere is conducted down to the ionosphere by electrons moving along the geomagnetic field. We find that observed stormtime ionosphere temperature increases can be explained by the heat conduction effect. Direct heating of the ionosphere by the ring current does occur during the peak of the storm, but that occurs after the ionosphere is already affected by heat conduction. Key Points: Comprehensive Inner Magnetosphere‐Ionosphere (CIMI)‐computed ring current heating is coupled into Sami3 is Also a Model of the Ionosphere to drive a simulation of the stormtime ionosphere and plasmasphereThe CIMI‐simulated model ring current is shown to directly heat both the plasmasphere and ionosphereWhen the model ring current heating is limited to plasmasphere heights, elevated ionosphere temperatures are similar to observations [ABSTRACT FROM AUTHOR]