Fine-scale dynamics of fragmented aurora-like emissions

Fragmented aurora-like emissions (FAEs) are small (few kilometres) optical structures which have been observed close to the poleward boundary of the aurora from the high-latitude location of Svalbard (magnetic latitude 75.3 ∘N). The FAEs are only visible in certain emissions, and their shape has no magnetic-field-aligned component, suggesting that they are not caused by energetic particle precipitation and are, therefore, not aurora in the normal sense of the word. The FAEs sometimes form wave-like structures parallel to an auroral arc, with regular spacing between each FAE. They drift at a constant speed and exhibit internal dynamics moving at a faster speed than the envelope structure. The formation mechanism of FAEs is currently unknown. We present an analysis of high-resolution optical observations of FAEs made during two separate events. Based on their appearance and dynamics, we make the assumption that the FAEs are a signature of a dispersive wave in the lower E-region ionosphere, co-located with enhanced electron and ion temperatures detected by incoherent scatter radar. Their drift speed (group speed) is found to be 580–700 m s−1, and the speed of their internal dynamics (phase speed) is found to be 2200–2500 m s−1, both for an assumed altitude of 100 km. The speeds are similar for both events which are observed during different auroral conditions. We consider two possible waves which could produce the FAEs, i.e. electrostatic ion cyclotron waves (EIC) and Farley–Buneman waves, and find that the observations could be consistent with either wave under certain assumptions. In the case of EIC waves, the FAEs must be located at an altitude above about 140 km, and our measured speeds scaled accordingly. In the case of Farley–Buneman waves a very strong electric field of about 365 mV m−1 is required to produce the observed speeds of the FAEs; such a strong electric field may be a requirement for FAEs to occur.

Tectonic Transport Directions, Shear Senses and Deformation Temperatures Indicated by Quartz c-Axis Fabrics and Microstructures in a NW-SE Transect across the Moine and Sgurr Beag Thrust Sheets, Caledonian Orogen of Northern Scotland

Moine metasedimentary rocks of northern Scotland are characterized by arcuate map patterns of mineral lineations that swing progressively clockwise from orogen-perpendicular E-trending lineations in greenschist facies mylonites above the Moine thrust on the foreland edge of the Caledonian Orogen, to S-trending lineations at higher structural levels and metamorphic grades in the hinterland. Quartz c-axis fabrics measured on a west to east coast transect demonstrate that the lineations developed parallel to the maximum principal extension direction and therefore track the local tectonic transport direction. Microstructures and c-axis fabrics document a progressive change from top to the N shearing in the hinterland to top to the W shearing on the foreland edge. Field relationships indicate that the domain of top to the N shearing was at least 55 km wide before later horizontal shortening on km-scale W-vergent folds that detach on the underlying Moine thrust. Previously published data from the Moine thrust mylonites demonstrate that top to the W shearing had largely ceased by 430 Ma, while preliminary isotopic age data suggest top to the N shearing occurred at ~470–450 Ma. In addition, data from the east coast end of our transect indicate normal-sense top down-SE shearing at close to peak temperatures at ~420 Ma that may be related to the closing stages of Scandian deformation, metamorphism and cooling/exhumation.

Odorization of Natural Gas: What are the Challenges?

Modern natural gas (NG) has little or no odor, so other compounds, usually mercaptans and thiols, are added as warning odorants. Federal regulations state that NG must be odorized so that it is readily detectable by people with normal senses of smell at one fifth the lower explosive limit, but regulations don't define "readily detectable" or "normal senses of smell." Methods to measure human odor detection have been available for decades. However, most previous work on NG odorants has underestimated human sensitivity, and measurements need to be repeated using the latest methods. More work is also needed to determine how odor sensitivity measured under optimal laboratory conditions is affected by real-world factors such as distraction and exposure to other odors in the environment. Regarding a "normal sense of smell," healthy people vary over orders of magnitude in the concentrations they can detect, so samples of subjects should be chosen to reflect the range of differences in the population.

On the kinematics and timing of Rodinia breakup: a possible rift–transform junction of Cryogenian age at the southwest cape of Congo Craton (northwest Namibia)

After tilt correction for Ediacaran thick-skinned folding, a pair of Cryogenian half grabens at the autochthonous southwest cape of Congo Craton (CC) in northwest Namibia restore to different orientations. Toekoms sub-basin trended east-northeast, parallel to Northern Zone (NZ) of Damara belt, and was bounded by a normal-sense growth fault (2 290 m throw) dipping 57° toward CC. Soutput sub-basin trended northwest, oblique to NZ and to north-northwest-trending Kaoko Belt. It was bounded by a growth fault (750 m down-dip throw) dipping steeply (~75°) toward CC. Soutput growth fault could be an oblique (splay) fault connecting a Cryogenian rift zone in NZ with a sinistral transform zone in Kaoko Belt. A transform origin for the Kaoko margin accords with its magma-poor abrupt shelf-to-basin change implying mechanical strength, unlike the magma-rich southern margin where a gradual shelf-to-basin change implies a mechanically weak extended margin. A rift−transform junction is kinematically compatible with observed north-northwest−south-southeast Cryogenian crustal stretching within CC. Post-rift subsidence of the CC carbonate platform varies strongly across the south-facing but not the west-facing shelf. A sheared western CC margin differs from existing Kaoko Belt models that posit orthogonal opening with hyper-extended continental crust. Carbonate-dominated sedimentation over southwest CC implies palaeolatitudes ≤35° between 770 and 600 Ma.

Six-month psychophysical evaluation of olfactory dysfunction in patients with COVID-19

This study prospectively assessed the six-month prevalence of self-reported and psychophysically measured olfactory dysfunction in subjects with mild-to-moderate COVID-19. Self-reported smell or taste impairment was prospectively evaluated by SNOT-22 at diagnosis, 4-week, 8-week, and 6-month. At 6 months from the diagnosis, psychophysical evaluation of olfactory function was also performed using the 34-item culturally adapted University of Pennsylvania Smell Identification Test (CA-UPSIT). 145 completed both the 6-month subjective and psychophysical olfactory evaluation. According to CA-UPSIT, 87 subjects (60.0%) exhibited some smell dysfunction, with 10 patients being anosmic (6.9%) and 7 being severely microsmic (4.8%). At the time CA-UPSIT was administered, a weak correlation was observed between the self-reported alteration of sense of smell or taste and olfactory test scores (Spearman’s r=-0.26). Among 112 patients who self-reported normal sense of smell at last follow-up, CA-UPSIT revealed normal smell in 46 (41.1%), mild microsmia in 46 (41.1%), moderate microsmia in 11 (9.8%), severe microsmia in 3 (2.3%), and anosmia in 6 (5.4%) patients; however, of those patients self-reporting normal smell but who were found to have hypofunction on testing, 62 out of 66 had self-reported reduction in sense of smell or taste at an earlier time point. Despite most patients report a subjectively normal sense of smell, we observed a high percentage of persistent smell dysfunction at 6 months from the diagnosis of SARS-CoV-2 infection, with 11.7% of patients being anosmic or severely microsmic. These data highlight a significant long-term rate of smell alteration in patients with previous SARS-COV-2 infection.

High prevalence of long-term psychophysical olfactory dysfunction in patients with COVID-19

This study prospectively assessed the long-term prevalence of self-reported and psychophysically measured olfactory dysfunction in subjects with mild-to-moderate COVID-19. Self-reported smell or taste impairment was prospectively evaluated by SNOT-22 at diagnosis, 4-week, 8-week, and 6-month. At 6 months from the diagnosis, psychophysical evaluation of olfactory function was also performed using the 34-item culturally adapted University of Pennsylvania Smell Identification Test (CA-UPSIT). 145 completed both the 6-month subjective and psychophysical olfactory evaluation. According to CA-UPSIT, 87 subjects (60.0%) exhibited some smell dysfunction, with 54 (37.2) being mildly microsmic, 16 (11.0%) moderately microsmic, 7 (4.8%) severely microsmic, and 10 patients (6.9%) being anosmic. At the time CA-UPSIT was administered, a weak correlation was observed between the self-reported alteration of sense of smell or taste and olfactory test scores (Spearman r=-0.26). Among 112 patients who self-reported normal sense of smell at last follow-up, CA-UPSIT revealed normal smell in 46 (41.1%), mild microsmia in 46 (41.1%), moderate microsmia in 11 (9.8%), severe microsmia in 3 (2.3%), and anosmia in 6 (5.4%) patients; however, of those patients self-reporting normal smell but who were found to have hypofunction on testing, 62 out of 66 had self-reported reduction in sense of smell or taste at an earlier time point. Despite most patients report a subjectively normal sense of smell, we observed a high percentage of persistent smell dysfunction at 6 months from the diagnosis of SARS-CoV-2 infection, with 11.7% of patients being anosmic or severely microsmic. These data highlight a significant long-term rate of smell alteration in patients with previous SARS-CoV-2 infection.

Fine Scale Dynamics of Fragmented Aurora-Like Emission

Fragmented Aurora-like Emissions (FAEs) are small (few km) optical structures which have been observed close to the poleward boundary of the aurora from the high-latitude location of Svalbard (magnetic latitude 75.3 ° N). The FAEs are only visible in certain emissions and their shape has no magnetic-field aligned component, suggesting that they are not caused by energetic particle precipitation and are therefore not aurora in the normal sense of the word. The FAEs sometimes form wave-like structures parallel to an auroral arc, with regular spacing between each FAE. They drift at a constant speed and exhibit internal dynamics moving at a faster speed than the envelope structure. The formation mechanism of FAEs is currently unknown. We present an analysis of high-resolution optical observations of FAEs made during two separate events. Based on their appearance and dynamics we make the assumption that the FAEs are a signature of a dispersive wave in the lower E-region ionosphere, co-located with enhanced electron and ion temperatures detected by incoherent scatter radar. Their drift speed (group speed) is found to be 580–700 m s−1 and the speed of their internal dynamics (phase speed) is found to be 2200–2500 m s−1, both for an assumed altitude of 100 km. The speeds are similar for both events which are observed during different auroral conditions. We consider two possible waves which could produce the FAEs, electrostatic ion cyclotron waves and Farley-Buneman waves, and find that the observations could be consistent with either wave under certain assumptions. In the case of EIC waves the FAEs must be located at an altitude above about 140 km, and our measured speeds scaled accordingly. In the case of Farley-Buneman waves a very strong electric field of about 365 mV m−1 is required to produce the observed speeds of the FAEs; such a strong electric field may be a requirement for FAEs to occur.

Loss of bacterial diversity in the sinuses is associated with lower smell discrimination scores

Olfactory impairment affects ~ 20% of the population and has been linked to various serious disorders. Microbes in the nasal cavity play a key role in priming the physiology of the olfactory epithelium and maintaining a normal sense of smell by the host. The aim of this study was to explore the link between olfactory dysfunction and nasal bacterial communities. A total of 162 subjects were recruited for this study from a specialized olfactory dysfunction clinic and placed into one of three groups: anosmia, hyposmia or normosmia. Swabs from the nasal middle meatus were collected from each subject then processed for bacterial 16S rRNA gene sequencing. No overall differences in bacterial diversity or composition were observed between the three cohorts in this study. However, the relative abundances of Corynebacterium spp. and Streptococcus spp. were significantly (p < 0.05) different in subjects with olfactory loss. Furthermore, subjects with deficiencies in discriminating between smells (based on discrimination scores) had a lower bacterial diversity (Simpson’s evenness p < 0.05). While these results are preliminary in nature, potential bacterial biomarkers for olfactory loss were identified. These findings need to be further validated and biologically tested in animal models.

Distribution, microphysical properties, and tectonic control of deformation bands in the Miocene accretionary prism (Whakataki Formation) of the Hikurangi subduction zone

We analyse deformation bands related to both horizontal contraction and horizontal extension in Miocene turbidites of the Whakataki Formation south of Castlepoint, Wairarapa, North Island, New Zealand. In the Whakataki Formation, four sets of cataclastic deformation bands are identified: (1) normal-sense Compactional Shear Bands (CSBs); (2) normal-sense Shear-Enhanced Compaction Bands (SECBs); (3) reverse-sense CSBs; and (4) reverse-sense SECBs. During extension, CSBs form most frequently with rare SECBs. Extensional CSBs are often, but not exclusively, associated with normal faults. During contraction, distributed SECBs are observed most commonly, sometimes clustering around small reverse faults and thrusts. Contractional CSBs are primarily found in the damage zones of reverse faults. The quantitative spacing analysis shows that most outcrops are characterised by mixed spatial distributions of deformation bands, interpreted as a consequence of overprint due to progressive deformation or distinct multiple generations of deformation bands from different deformation phases. Since many deformation bands are parallel to adjacent juvenile normal- and reverse-faults, bands are likely precursors to faults. With progressive deformation, the linkage of distributed deformation bands across sedimentary beds occurs to form through-going faults. During this process, bands associated with the wall-, tip-, and interaction damage zones overprint earlier distributions resulting in complex spatial patterns. Regularly spaced bands are pervasively distributed when far away from faults. Microstructural analysis shows that all deformation bands form by inelastic pore collapse and grain crushing with an absolute reduction in porosity relative to the host rock between 5 and 14 %. Hence, deformation bands likely act as fluid flow barriers. Faults and their associated damage zones exhibit a spacing of order ten metres on the scale of 10 km and are more commonly observed in areas characterised by higher mudstone to sandstone ratios. As a result, extensive clay smear is common in these faults, enhancing the sealing capacity of faults. Therefore, the formation of deformation bands and faults leads to progressive flow compartmentalisation from the scale of ten metres down to about ten centimetres, the typical spacing of distributed deformation bands.