The exchange of energy between the lower atmosphere and the ionosphere thermosphere system is not well understood. One of the parameters that is important in the lower thermosphere is atomic oxygen. It has recently been observed that atomic oxygen is higher in summer at ∼95 km. In this study, we investigate the sensitivity of the upper thermosphere to lower thermospheric atomic oxygen using the Global Ionosphere Thermosphere Model (GITM). We use the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X) to drive the lower atmospheric boundary of atomic oxygen in GITM between ∼95 and 100 km and compare the results with the current mass spectrometer incoherent scatter (MSIS) driven GITM. MSIS has higher atomic oxygen in the winter hemisphere while WACCM-X has higher atomic oxygen in the summer hemisphere. The reversal of atomic oxygen distribution affects the pressure distribution between 100 and 120 km, such that the hemisphere with larger O number density has stronger equatorward winds, and lower temperature mainly due to adiabatic and radiative cooling. This affects thermospheric scale heights such that the hemisphere with more O has lower N 2 and thus enhanced O/N 2. This behavior is observed in the opposite hemisphere when MSIS is used as the lower boundary for GITM. Overall, O/N 2 for WACCM-X driven GITM matches better with the global ultraviolet imager (GUVI) data. We find that the impact of lower thermospheric atomic oxygen on upper thermosphere is not just through diffusive equilibrium but also through secondary effects on winds and temperature.

IntroductionDissolution of the enamel in the form of erosion has increased due to shift in eating habits toward carbonated drinks like soft drink and chocolates.AimThe purpose of this study was to evaluate changes in the salivary pH after intake of different eatables and beverages in children at different time intervals.Study designUsing standard salivary tests, this study was conducted as a case-control study. Fifty children between ages of 8 and 12 years having strict vegetarian diet were included in the study.Materials and methodsOral prophylaxis was done and salivary buffer capacity for stimulated saliva was measured. Before the saliva collection, each of the children was informed not to eat or drink anything for up to 2 hours just before the appointment.ResultsOn pairwise evaluation, all the differences were found to be significant statistically except between baseline vs 30 minutes. Maximum mean difference was calculated and observed between baseline and immediately after intake of fruit juice and immediate after 30 minutes, 0.953 and 0.963 respectively, while minimum difference was calculated and observed between baseline and 30 minutes after intake of fruit juice (0.010).ConclusionMaximum drop was seen in cold drink when compared with fruit juice. The maximum pH increase was observed in cream biscuits with 7.63 ± 0.20. It was observed that in all the groups, the pH gradually got back to near normal levels due to the buffering mechanism of saliva.How to cite this article: Pachori A, Kambalimath H, Maran S, Niranjan B, Bhambhani G, Malhotra G. Evaluation of Changes in Salivary pH after Intake of Different Eatables and Beverages in Children at Different Time Intervals. Int J Clin Pediatr Dent 2018;11(3):177-182.

The equatorial quasi‐biennial oscillation (QBO) is known to be an important source of interannual variability in the middle‐ and high‐latitude stratosphere. The influence of the QBO on the stratospheric polar vortex in particular has been extensively studied. However, the impact of the QBO on the winds of the midlatitude mesosphere is much less clear. We have applied 13 years (2002–2014) of data from the Saskatoon Super Dual Auroral Radar Network HF radar to show that there is a strong QBO signature in the midlatitude mesospheric zonal winds during the late winter months. We find that the Saskatoon mesospheric winds are related to the winds of the equatorial QBO at 50 hPa such that the westerly mesospheric winds strengthen when QBO is easterly, and vice versa. We also consider the situation in the late winter Saskatoon stratosphere using the European Centre for Medium‐Range Weather Forecasts ERA‐Interim reanalysis data set. We find that the Saskatoon stratospheric winds between 7 hPa and 70 hPa weaken when the equatorial QBO at 50 hPa is easterly, and vice versa. We speculate that gravity wave filtering from the QBO‐modulated stratospheric winds and subsequent opposite momentum deposition in the mesosphere plays a major role in the appearance of the QBO signature in the late winter Saskatoon mesospheric winds, thereby coupling the equatorial stratosphere and the midlatitude mesosphere.

This article discusses a case of an 8-year-old female child who presented with severe lower anterior crowding and congenitally missing lower second premolars. A conventional serial extraction procedure could not be performed due to the congenital absence of teeth. Instead, planned extraction of a few primary teeth was done to relieve the lower anterior crowding, the results of which were near satisfactory.