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We performed first-principles density functional theory (DFT) calculations to numerically investigate the electronic band structures of penta-graphene (PG), a novel two-dimensional carbon material with a pentagonal lattice structure, and its chemically functionalized forms. Specifically, we studied hydrogenated PG (h-PG), fluorinated PG (f-PG), and chlorinated PG (Cl-PG). We used the generalized gradient approximation (GGA) and the hybrid Heyd–Scuseria–Ernzerhof (HSE06) exchange-correlation functional in the DFT-based software VASP to capture electronic properties accurately. Our results indicate that hydrogenation and fluorination increased the indirect bandgap of PG from 3.05 eV to 4.97 eV and 4.81 eV, respectively, thereby effectively transforming PG from a semiconductor to an insulator. In contrast, we found that chlorination closed the bandgap, thus indicating the metallic behavior of Cl-PG. These results highlight the feasibility of tuning the electronic properties of PG through functionalization, offering insight into designing new materials for nanoelectronic applications.

We report the first simultaneous observations of total electron content (TEC), radio signal scintillation, and precise point positioning (PPP) variation associated with Strong Thermal Emission Velocity Enhancement (STEVE) emissions during a 26 March 2008 storm‐time substorm. Despite that the mid‐latitude trough TEC decreases during the substorm overall, interestingly, we found an unexpected TEC enhancement (by ∼2 TECU) during STEVE. Enhancement of vertical TEC and phase scintillation was highly localized to STEVE within a thin latitudinal band of 1°. As STEVE shifted equatorward, TEC enhancement was found at and slightly poleward of the optical emission. PPP exhibited enhanced variation across a 3° latitudinal range around STEVE and indicated increased GNSS positioning error. We suggest that TEC enhancement during STEVE creates local TEC structures in the ionosphere that degrade Global Navigation Satellite Systems (GNSS) signals and PPP performance. The TEC enhancement may be created by particle precipitation, Pedersen drift across STEVE, neutral wind, or plasma instability. Plain Language Summary: Global Navigation Satellite Systems (GNSS) signals experience phase and amplitude fluctuations known as scintillation when traveling through density irregularities in the ionosphere. The ionospheric density structures created during Strong Thermal Emission Velocity Enhancement (STEVE) have not yet been characterized in the literature. We combine ground‐based imaging and measurements of ionospheric density to show that STEVE creates unusually steep density gradients and small‐scale density irregularities. We find enhanced phase scintillation and increased GNSS positioning error in GNSS receiver stations where STEVE transects the line of sight between the receiver and satellite. The ionospheric density irregularities associated with STEVE are highly localized and suspected to be connected to particle precipitation and plasma drift during STEVE. These results quantify STEVE's impact on ionospheric dynamics and GNSS navigation for the first time. Key Points: A distinct TEC enhancement was found in the subauroral ionosphere during STEVEThe scintillation indices show significant GNSS phase and amplitude fluctuations during the TEC gradientsPrecise point positioning variations show enhanced GNSS positioning error during STEVE [ABSTRACT FROM AUTHOR]

We performed first-principles density functional theory (DFT) calculations to numerically investigate the electronic band structures of penta-graphene (PG), a novel two-dimensional carbon material with a pentagonal lattice structure, and its chemically functionalized forms. Specifically, we studied hydrogenated PG (h-PG), fluorinated PG (f-PG), and chlorinated PG (Cl-PG). We used the generalized gradient approximation (GGA) and the hybrid Heyd–Scuseria–Ernzerhof (HSE06) exchange-correlation functional in the DFT-based software VASP to capture electronic properties accurately. Our results indicate that hydrogenation and fluorination increased the indirect bandgap of PG from 3.05 eV to 4.97 eV and 4.81 eV, respectively, thereby effectively transforming PG from a semiconductor to an insulator. In contrast, we found that chlorination closed the bandgap, thus indicating the metallic behavior of Cl-PG. These results highlight the feasibility of tuning the electronic properties of PG through functionalization, offering insight into designing new materials for nanoelectronic applications. [ABSTRACT FROM AUTHOR]

Although Strong Thermal Emission Velocity Enhancement (STEVE) and subauroral ion drifts (SAID) are often considered in the context of geomagnetically disturbed times, we found that STEVE and SAID can occur even during quiet times. Quiet‐time STEVE has the same properties as substorm‐time STEVE, including its purple/mauve color and occurrence near the equatorward boundary of the pre‐midnight auroral oval. Quiet‐time STEVE and SAID emerged during a non‐substorm auroral intensification at or near the poleward boundary of the auroral oval followed by a streamer. Quiet‐time STEVE only lasted a few minutes but can reappear multiple times, and its latitude was much higher than substorm‐time STEVE due to the contracted auroral oval. The THEMIS satellites in the plasma sheet detected dipolarization fronts and fast flows associated with the auroral intensification, indicating that the transient energy release in the magnetotail was the source of quiet‐time STEVE and SAID. Particle injection was weaker and electron temperature was lower than the events without quiet‐time STEVE. The plasmapause extended beyond the geosynchronous orbit, and the ring current and tail current were weak. The interplanetary magnetic field (IMF) Bz was close to zero, while the IMF Bx was dominant. We suggest that the small energy release in the quiet magnetosphere can significantly impact the flow and field‐aligned current system. Plain Language Summary: The purple/mauve‐colored Strong Thermal Emission Velocity Enhancement (STEVE) emissions tend to occur at mid‐latitudes during geomagnetically active times. We found that STEVE also occurs during geomagnetically quiet times. The occurrence region is much higher in latitude because the auroral oval is smaller during quiet times. Quiet‐time STEVE only lasted a few minutes but can occur repetitively. Quiet‐time STEVE is preceded by a weak auroral intensification and is associated with fast plasma streams in the ionosphere. The Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites in the magnetotail detected a sudden energy release, which is suggested to be the energy source for the auroral intensification and quiet‐time STEVE. THEMIS also showed that the magnetosphere was very quiet and the temperature of the plasma sheet electrons was unusually low. We suggest that the sudden energy release in the quiet magnetosphere drive unexpectedly intense plasma streams and quiet‐time STEVE. Key Points: Strong Thermal Emission Velocity Enhancement (STEVE) and subauroral ion drifts (SAID) are observed during geomagnetically quiet times when a weak auroral intensification occursQuiet‐time STEVE is associated with fast flows in the tail but injection is weak and temperature is lowThe quiet magnetosphere can have unique particle and current structures that drive SAID flows similar to storm times [ABSTRACT FROM AUTHOR]

With the advent of the Heliophysics/Geospace System Observatory (H/GSO), a complement of multi-spacecraft missions and ground-based observatories to study the space environment, data retrieval, analysis, and visualization of space physics data can be daunting. The Space Physics Environment Data Analysis System (SPEDAS), a grass-roots software development platform (www.spedas.org), is now officially supported by NASA Heliophysics as part of its data environment infrastructure. It serves more than a dozen space missions and ground observatories and can integrate the full complement of past and upcoming space physics missions with minimal resources, following clear, simple, and well-proven guidelines. Free, modular and configurable to the needs of individual missions, it works in both command-line (ideal for experienced users) and Graphical User Interface (GUI) mode (reducing the learning curve for first-time users). Both options have "crib-sheets," user-command sequences in ASCII format that can facilitate record-and-repeat actions, especially for complex operations and plotting. Crib-sheets enhance scientific interactions, as users can move rapidly and accurately from exchanges of technical information on data processing to efficient discussions regarding data interpretation and science. SPEDAS can readily query and ingest all International Solar Terrestrial Physics (ISTP)-compatible products from the Space Physics Data Facility (SPDF), enabling access to a vast collection of historic and current mission data. The planned incorporation of Heliophysics Application Programmer's Interface (HAPI) standards will facilitate data ingestion from distributed datasets that adhere to these standards. Although SPEDAS is currently Interactive Data Language (IDL)-based (and interfaces to Java-based tools such as Autoplot), efforts are under-way to expand it further to work with python (first as an interface tool and potentially even receiving an under-the-hood replacement). We review the SPEDAS development history, goals, and current implementation. We explain its "modes of use" with examples geared for users and outline its technical implementation and requirements with software developers in mind. We also describe SPEDAS personnel and software management, interfaces with other organizations, resources and support structure available to the community, and future development plans.Electronic supplementary materialThe online version of this article (10.1007/s11214-018-0576-4) contains supplementary material, which is available to authorized users.

Opioid use disorder (OUD)-associated overdose deaths have reached epidemic proportions worldwide over the past two decades, with death rates for men reported at twice the rate for women. Using a controlled, cross-sectional, age-matched (18–56 y) design to better understand the cognitive neuroscience of OUD, we evaluated the electroencephalographic (EEG) responses of male and female participants with OUD vs. age- and gender-matched non-OUD controls during a simple visual object recognition Go/No-Go task. Overall, women had significantly slower reaction times (RTs) than men. In addition, EEG N200 and P300 event-related potential (ERP) amplitudes for non-OUD controls were significantly larger for men, while their latencies were significantly shorter than for women. However, while N200 and P300 amplitudes were not significantly affected by OUD for either men or women in this task, latencies were also affected differentially in men vs. women with OUD. Accordingly, for both N200 and P300, male OUD participants exhibited longer latencies while female OUD participants exhibited shorter ones than in non-OUD controls. Additionally, robust oscillations were found in all participants during a feedback message associated with performance in the task. Although alpha and beta power during the feedback message were significantly greater for men than women overall, both alpha and beta oscillations exhibited significantly lower power in all participants with OUD. Taken together, these findings suggest important gender by OUD differences in cognitive processing and reflection of performance in this simple visual task.

Strong Thermal Emission Velocity Enhancement (STEVE), is a captivating optical phenomenon typically observed in the mid‐latitude ionosphere. This paper presents an intriguing observation of a STEVE event at high‐latitudes, approximately 10 degrees poleward of previously documented observations. This event was recorded in Yellowknife, Canada, by a TREx RGB imager and a citizen scientist. Swarm satellites traversed the latitude of the observation, measuring extreme westwards ion drift velocities exceeding 4 km/s. Such velocities are more typically associated with the subauroral region located at mid‐latitudes, rather than at the high‐latitudes reported here. Significantly, this event occurred without a substorm, which differs from previous STEVE observations. While high‐latitude radars detected fast ionospheric equatorward flows, GOES satellite did not record any injections. These observations suggest that the inner magnetosphere is highly inflated. This unique case study raises new questions surrounding subauroral dynamics and the influence of magnetospheric configurations on ionospheric responses. Plain Language Summary: Strong Thermal Emission Velocity Enhancement, also known as STEVE, is a fascinating nighttime optical phenomenon that takes place in the upper part of Earth's atmosphere. It can be easily recognized by its distinctive appearance as a narrow white‐mauve arc that is associated with strong westward flows and is situated just equatorward of the auroral oval. Previous research has shown that STEVE events occur together with intense ionospheric flows and occur after specific disturbances in the near‐Earth space environment known as substorms. They have found that substorms are important for creating the special conditions that lead to STEVE and other subauroral enhancements. In our study, we focus on a unique STEVE event that did not occur after a substorm. Furthermore, this observation took place under remarkably quiet solar wind conditions; nevertheless, strong ionospheric flows were recorded. This unusual case raises new questions about the atmospheric responses and how it is affected by the configuration of the magnetic field in space. By investigating these special circumstances, we hope to learn more about STEVE and its causes, which will help us advance our knowledge in the complex ionosphere‐magnetosphere‐solar wind coupled system. Key Points: Non‐storm and non‐substorm Strong Thermal Emission Velocity Enhancement (STEVE) occurrenceStrong subauroral flows during quiet geomagnetic conditionsThe ionospheric electrodynamics of this STEVE event differ from previous studies [ABSTRACT FROM AUTHOR]

Energetic proton precipitation from the magnetosphere plays an important role in the magnetosphere‐ionosphere‐thermosphere coupling and energy transfer. Proton precipitation causes hydrogen emissions, such as Hβ (486.1 nm), and also triggers the excitation of other emission lines such as the blue‐line (427.8 nm) and the green‐line (557.7 nm). In light of the growing availability of ground‐based proton auroral measurements in recent years, we revisit the proton auroral modeling in this study, with more focus on the application for interpreting ground observations. An accurate simulation of these optical emissions requires a comprehensive understanding of particle transport and collisions in the upper atmosphere, where the simultaneous consideration of precipitating protons, newly generated energetic hydrogen atoms, and secondary electrons is critical. For this purpose, we couple a 3D Monte‐Carlo proton transport model and an electron transport model. The integrated model framework can compute the emission rates of most major auroral emission lines/bands resulting from proton precipitation, along with self‐consistent calculation of the ionospheric electron density variations. The model results show improved agreement with ground optical observations in terms of the Hβ yield and the green‐to‐Hβ ratio compared to previous model studies. Our new model is a valuable tool for quantifying excitation and ionization due to proton aurora. It has the potential to leverage ground observations to infer precipitating conditions at high altitudes and even for studying magnetospheric activity. Plain Language Summary: The terrestrial auroral display is caused by the collision of energetic particles from space with the Earth's atmosphere. Both energetic electrons and protons can enter the atmosphere and cause auroras, but their transport processes are different. The proton can exchange its charge with atmospheric neutral particles in a collision and become a neutral hydrogen atom, and the hydrogen atom can become a proton again in another collision with atmospheric particles. Both the protons and the hydrogens can ionize the atmospheric neutrals and produce secondary electrons. To model the proton‐induced auroras, the three components, protons, hydrogens, and secondary electrons, must be considered together with their different trajectories and transport in the atmosphere. In this study, we present such a coupled proton‐hydrogen‐electron transport model and simulate the resulting proton auroral intensities. The model results show reasonable agreement with existing ground‐based observations. Key Points: We present a model of coupled proton‐hydrogen‐electron transport in the atmosphere and the resulting auroral excitation and ionizationThe model results show improved agreement with the Hbeta yield reported in existing observations compared to previous modelsOur model can simulate the 557.7 nm emission in proton auroras. The modeled green‐to‐Hbeta ratio is compatible with the existing observation [ABSTRACT FROM AUTHOR]

Omega bands are mesoscale auroral structures emerging as eastward moving quasi‐periodic poleward protrusions well within the closed field line region of the auroral oval. Neither specific conditions of their appearance nor their causes are well understood. We perform a superposed epoch analysis of OMNI and SuperMAG measurements taken during 28 omega band events recorded by auroral all‐sky imager observations from 2006 to 2013 to identify their solar wind drivers. We find local enhancements in the solar wind flow speed, magnetic field, pressure, and proton density at the time of the omega band observation. In the magnetosphere‐ionosphere, we see enhancements in the ring current, partial ring current, and auroral electrojets. These features are consistent with geomagnetic activity caused by stream interaction regions (SIRs). 19 of our events overlap with SIRs from published event catalogs. Our findings suggest that omega bands are driven by compression regions commonly associated with SIR events. Plain Language Summary: Omega bands are eastward moving wave‐like structures in the aurora that typically appear at the equatorward border of the auroral oval during periods of enhanced activity in Earth's magnetosphere. However, the specific drivers of these structures are not well understood. In this work, we perform a statistical analysis of spacecraft observations taken from multiple omega band events to identify potential drivers of these structures. We find that the solar wind exhibits increased speed, pressure, and particle density when omega bands appear overhead. These features are consistent with localized compression in the solar wind generated when a fast solar wind stream interacts with a slower leading stream. Our work suggests that the appearance of omega bands is driven by this compression. Key Points: A statistical analysis of 28 omega band events shows that they are driven by extended periods of enhanced solar wind density19 of the 28 omega band events studied occurred during documented stream interaction region events in the solar windAnalysis of the flow speed during all 28 events indicate that omega bands are driven by compression regions rather than high speed streams [ABSTRACT FROM AUTHOR]

An approach for creating continental‐scale, multi‐scale plasma convection maps in the nightside high‐latitude ionosphere using the spherical elementary current systems technique has been developed and evaluated. The capability to reconstruct meso‐scale flow channels improved dramatically, and the velocity errors were reduced by ∼30% compared to the spherical harmonic fitting method. Uncertainties of velocity vectors estimated by varying the model setup was also low. Convection maps for a substorm event revealed multiple flow channels in the polar cap, dominating the convection in the quiet time and early growth phase. The meso‐scale flows extended toward the nightside auroral oval and had continuous flow channels over >20° of latitude, and the flow channels dynamically merged and bifurcated. The substorm onset occurred along one of the flow channels, and the azimuthal extent of the enhanced flows coincided with the initial width of the auroral breakup. During the expansion phase, the meso‐scale flows repetitively crossed the oval poleward boundary, and some of them contributed to subauroral polarization streams enhancements. Increased flows extended duskward, along with the westward traveling surge. Then, flows near midnight weakened and evolved to the Harang flow shear. The meso‐scale flow channels had significant (∼10%–40% on average) contributions to the total plasma transport. The meso‐scale flows were highly variable on ∼10 min time scales and their individual maximum contributions reached upto 73%. These results demonstrate the capability of specifying realistic convection patterns, quantifying the contribution of meso‐scale transport, and evaluating the relationship between meso‐scale flows and localized auroral forms. Key Points: High‐resolution convection maps in the nightside high‐latitude ionosphere were created with small errors and good agreement with Defense Meteorological Satellite ProgramThe convection maps revealed a dynamic interplay of multiple flow channels during a substorm, including precursor flows to substorm onsetThe meso‐scale flows contribute to ∼10%–40% of the total flows on average. The contribution increases up to 73% during flow bursts [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNTs) are an alternative for storage with low cost, eco-friendly, and good performance for both process adsorption and desorption. Herein, a purification procedure of MWCNTs was successfully described and studied by using XRD, TEM, Raman spectroscopy and by means of N2 adsorption-desorption isotherms using the BET method. The H2 storage properties at room temperature of the purified carbon nanotubes exposed to gas under pressures between 0.39 and 13.33 kPa was investigated by using the quartz crystal microbalance technique. It was found that the H2 adsorption capacity is strongly dependent on the morphological and structural characteristics of the carbon nanotubes and their specific surface area. The best sample with specific surface area of 729.4 ± 3 m2 g−1 shows a maximum adsorption capacity of 3.46 wt% at 12.79 kPa of H2 exposure pressure. The adsorption kinetics (t95%) from the different purified MWCNTs was also investigated as a function of the H2 exposure pressure as well as the performance of these MWCNTs on the reversibility of the H2 loading/unloading process when underwent to successive cycles of gas exposure.

The photocatalytic conversion in aqueous media of phenol and guaiacol as a lignin model compound using Nb2O5 with different crystal phases was studied. Nb2O5 particles were synthesized using hydrothermal methods, where it was observed that changes in the solvent control their morphology and crystal phase. Different photocatalytic behavior of Nb2O5 was observed with the selected model compounds, indicating that its selection directly impacts the resulting conversion and selectivity rates as well as the reaction pathway, highlighting the relevance of model molecule selection. Photocatalytic conversion of phenol showed conversion rate (C%) up to 25 % after 2 h irradiation and high selectivity (S%) to pyrogallol (up to 50 %). Orthorhombic Nb2O5 spheres favored conversion through free hydroxyl radicals while monoclinic rods did not convert phenol. Guaiacol photocatalytic oxidation showed high conversion rate but lower selectivity. Orthorhombic and monoclinic Nb2O5 favored the formation of resorcinol with S % ~0.43 % (C % ~33 %) and ~13 % (C % ~27 %) respectively. The mixture of both phases enhanced the guaiacol conversion rate to ~55 % with ~17 % of selectivity to salicylaldehyde. The use of radical scavengers provided information to elucidate the reaction pathway for these model compounds, showing that different reaction pathways may be obtained for the same photocatalyst if the model compound is changed. [ABSTRACT FROM AUTHOR]

The relationship between auroral, ground, and plasma sheet signatures in the late growth phase is crucial for understanding the sequence of events during a substorm expansion phase onset. Here we show conjugate ground‐auroral‐satellite observations of a substorm that occurred on 18 September 2021, between 04:45 and 05:00 UT, where four auroral activations were detected in the all‐sky imagers. An initial activation showed the brightening of an equatorward arc within the cutoff of the 630 nm emissions, indicating activity on closed field lines well inside the open‐closed field line boundary (OCFLB). During a second activation, auroral beads were observed on a brightening arc, equatorward and within the OCFLB, followed by the transformation from small‐scale to large‐scale vortices. The tail current sheet was highly disturbed during the auroral vortex evolution, including pressure and magnetic disturbances, an apparent broadening of a previously thin current sheet, and a breakdown of the frozen‐in condition. Our observations clearly show late growth phase dynamics, including arc brightenings, the formation of auroral beads, and auroral vortex development, can occur well in advance of fast Earthward flows in the tail. Indeed, it is only during that later activity that auroral breakup and strong Earthward flows, which we associate with magnetic reconnection further down the tail, are observed together with strong magnetic bays on the ground. The sequence of events is consistent with an inside‐to‐outside model at substorm expansion phase onset, most likely via a shear‐flow ballooning instability in the transition region from dipole to tail‐like fields in the near‐Earth plasma sheet. Plain Language Summary: Substorm onset is associated with the explosive release of stored magnetic energy, which can be visualized as auroral activity in the ionosphere, magnetic‐field disturbances in the ground‐based magnetometers, and plasma sheet disturbances in the magnetosphere. Even though the processes that lead to energy storage are well known, the exact sequence of events and the triggering factors that lead to the release of this stored energy are poorly understood. In this study, we show conjugate auroral‐ground‐satellite observations of a substorm event that occurred on 18 September 2021. Four auroral activations were observed in the all‐sky imagers, all of which can be associated with plasma sheet disturbances observed in the satellites. Our observations show an initial activation and bead‐like structures on a brightening arc, followed by the formation and expansion of vortex‐like auroral forms, all of which can be associated with magnetic field and pressure fluctuations in the near‐Earth nightside magnetosphere on closed field lines. Auroral breakup and strong magnetic bays on the ground are only observed after the arrival of fast Earthward flows in the magnetosphere. Overall, this paper identifies disturbances in the near‐Earth plasma environment which are the counterparts to the evolving auroral forms seen leading up to the substorm expansion phase onset. Key Points: Plasma sheet dynamical counterparts are reported for an evolving sequence of late growth phase auroral formsPlasma sheet current disruption and ion kinetic scale perturbations occur in advance of fast Earthward flows and magnetic reconnectionOne‐to‐one correspondence between plasma sheet disturbances and auroral forms implies ballooning instability in advance of auroral breakup [ABSTRACT FROM AUTHOR]

The intensity of use of a location is one of the most studied properties of animal movement, yet movement analyses generally focus on the overall use of a location without much consideration of how patterns in intensity of use emerge. Extracting properties related to intensity of use, such as the number of visits, the average and variation in time spent and the average and variation in time between visits, could help provide a more mechanistic understanding of how animals use landscape. Combining and synthesizing these properties into a single spatial representation could inform the role that a location plays for an animal.We developed an R package named 'UseScape' that allows the extraction of these metrics and then clustered them using mixture modelling to create a spatial representation of the type of use an animal makes of the landscape. We illustrate applications of the approach using datasets of animal movement from four taxa and highlight species‐specific and cross‐species insights.Our framework highlights properties that functionally differ in how animals use them, contrasting, for example, heavily used locations that emerge because they are frequented for long durations, locations that are repeatedly and regularly visited for shorter durations of time or locations visited irregularly. We found that species generally had similar types of use, such as typical low, mid and high use, but there were also species‐specific clusters that would have been ignored when only focusing on the overall intensity of use.Our multi‐system comparison highlighted how the framework provided novel insights that would not have been directly obtainable by currently available approaches. By making the framework available as an R package, these analyses can be easily applicable to a myriad of systems where relocation data are available. Movement ecology as a field can strongly benefit from approaches that not just describe patterns in space use, but also highlight the behavioural mechanisms leading to these emerging patterns. [ABSTRACT FROM AUTHOR]

Objective. Although earlier studies have suggested that early continuous airway positive pressure (CPAP) may be beneficial in reducing ventilator dependence and subsequent chronic lung disease in the extremely low birth weight (ELBW) infant, the time of initiation of CPAP has varied, and there are no prospective studies of infants who have received CPAP or positive end-expiratory pressure (PEEP) from initial resuscitation in the delivery room (DR). Current practice for the ELBW infant includes early intubation and the administration of prophylactic surfactant, often in the DR. The feasibility of initiating CPAP in the DR and continuing this therapy without intubation for surfactant has never been determined prospectively in a population of ELBW infants. This study was designed to determine the feasibility of randomizing ELBW infants of 0.3 with an oxygen saturation by pulse oximeter of 55 mm Hg, or apnea requiring bag and mask ventilation. Results. A total of 104 infants were enrolled over a 6-month period: 55 CPAP and 49 control infants. No infant was intubated in the DR for the exclusive purpose of surfactant administration. Forty-seven infants were intubated for resuscitation in the DR: 27 of 55 CPAP infants and 20 of 49 control infants. Only 4 of the 43 infants who had a birth weight of

In this paper we discuss conditions under which charged particles are confined by an axisymmetric longitudinal magnetic field with power law dependence on the radius. We derive a transcendental equation for the critical speed corresponding to the threshold between bounded and unbounded trajectories of the particles. This threshold speed shows strong dependence on the direction, and this dependence becomes more prominent as the exponent of the power law increases. The equation for threshold speed can be solved exactly for several specific values of the power exponent, but in general it requires a numerical treatment. Remarkably, if the magnetic field magnitude decreases more slowly than the inverse of the radius, charged particles remain confined no matter how large their energies may be. Key words: particle orbit theory, motion in magnetic field, escape velocity, transcendental equation, power law. Nous discutons les conditions sous lesquelles les particules chargees sont confinees par un champ magnetique longitudinal axisymetrique avec une dependance radiale en loi de puissance. Nous derivons une equation transcendantale pour la vitesse critique correspondante au seuil entre les trajectoires liees et les trajectoires libres des particules. La vitesse de seuil montre une forte dependance sur la direction et cette dependance devient plus importante lorsque l'exposant de la loi de puissance augmente. L'equation pour la vitesse de seuil peut etre solutionnee exactement pour plusieurs valeurs specifiques de l'exposant, mais en general, la solution est numerique. Il est remarquable de constater que si la magnitude du champ magnetique diminue plus lentement que l'inverse du rayon, la particule chargee reste confiner, quelle que soit son energie. [Traduit par la Redaction] Mots-cles : theorie orbitale des particules, mouvement dans un champ magnetique, vitesse de liberation ou d'echappement, equation transcendantale, loi de puissance., 1. Introduction Investigating trajectories of objects in various circumstances is one of the oldest and most fundamental problems of classical mechanics. A particular example of this problem, namely, motion of [...]

This paper provides a closed-form solution to the indefinite integral of a ratio of generalized polynomials where the denominator polynomial is raised to the general order r∈Z+. Such an integral arises in physics and engineering, the solution of which allows for closed-form analysis.

We utilized a 4K imaging to examine properties of fine‐scale structures of Strong Thermal Emission Velocity Enhancement (STEVE) near the magnetic zenith. Its high spatial (0.09 km at 200 km altitude) and temporal (24 Hz) resolution provided unprecedented details of fine‐scale structures in the subauroral ionosphere. Although the STEVE emission was seen as a homogeneous purple/mauve arc in the all‐sky images, the high‐speed imaging revealed that STEVE contained substantial multi‐scale structures. The characteristic wavelength and period were 12.4 ± 7.4 km and 1.4 ± 0.8 s, and they drifted westward at 8.9 ± 0.7 km/s. The speed is comparable to the reported magnitude of the intense subauroral ion drifts (SAID), suggesting that the fine‐scale structures are an optical manifestation of the E × B drift in the intense SAID. A spectral analysis identified multiple peaks at >10, 4, 2, 1.1, and <1/5 s period (>83, 33, 16, 9, and <1.7 km wavelength). Although most of the fine‐scale structures were stable during the drift across the field of view, some of the structures dynamically evolved within a few tens of km. The fine‐scale structures have a power law spectrum with a slope of −1, indicating that shear flow turbulence cascade structures to smaller scales. The fine‐scale structures pose a challenge to the subauroral ionosphere‐thermosphere interaction about how the ionosphere creates such fine‐scale structures and how the thermosphere reacts much faster than expected from a typical chemical reaction time. Plain Language Summary: Strong Thermal Emission Velocity Enhancement (STEVE) is often perceived as a homogeneous arc with a purple or mauve color. However, this notion is based on photographs with a long exposure time. We conducted a 4K video observation of STEVE with unprecedentedly high spatial and temporal resolution. The video revealed that STEVE is not a homogeneous arc but consists of rich fine‐scale structures that could not be seen in regular photographs. The fine‐scale structures had wavelengths of 1–10 s of km with multiple spectral peaks. The fine‐scale structures moved westward at 8.9 km/s. We suggest that the fine‐scale structures of STEVE correspond to fine‐scale plasma structures in the fast plasma streams in the upper atmosphere. However, it is challenging to explain how the upper atmospheric glow can form the fine‐scale structure because of the long chemical reaction time. Key Points: Citizen scientist photographs revealed fine‐scale structures of Strong Thermal Emission Velocity EnhancementThe fine‐scale structures extend down to a 9 km size, possibly even below a 1 km size. They propagate at 8.9 km/s westwardThe power law spectrum with a slope of −1 suggests a shear flow turbulence by the intense subauroral ion drifts [ABSTRACT FROM AUTHOR]