Outbreak of Negative Narrow Bipolar Events in Two Mid-Latitude Thunderstorms Featuring Overshooting Tops

Lightning discharges are the electrical production in thunderclouds. They radiate the bulk of radio signals in the very low-frequency and low-frequency (VLF/LF) that can be detected by ground-based receivers. One kind of special intra-cloud lightning discharges known as narrow bipolar events (NBEs) have been shown to be rare but closely linked to the convective activity that leads to hazardous weather. However, there is still lack of understanding on the meteorological conditions for thunderstorm-producing NBEs, especially for those of negative polarity, due to their rare occurrence. In this work, we aim to investigate what meteorological and electrical conditions of thunderclouds favor the production of negative NBEs. Combining with the VLF/LF radio signal measured by Jianghuai Area Sferic Array (JASA), S-band Doppler radar observation and balloon sounding data, two mid-latitude thunderstorms with outbreaks of negative NBEs at midnight in East China were analyzed. The comparison with the vertical radar profile shows that the bursts of negative NBEs occurred near thunderclouds with overshooting tops higher than 18 km. Manifestation of negative NBEs is observed with a relatively low spectrum width near thundercloud tops. Our findings suggest that the detection of negative NBEs would provide a unique electrical means to remotely probe overshooting tops with implications for the exchange of troposphere and stratosphere.

A Laboratory Investigation of the Probable Mechanisms of the Action of an Artificial Thunderstorm Cell on Model Aircraft Radomes

The results of experimental laboratory investigations of possible mechanisms of the impact of lightning and thunderclouds on aircraft radomes and equipment inside them are presented. An artificial thunderstorm cell of negative polarity and model aircraft radomes with lightning diverter strips have been used. Experiments have shown that the discharge processes in a radome model significantly depend on the magnitude of the charge that accumulates on the inner and outer surfaces of the radome shell. It is established that the accumulation of large-magnitude charges of different signs on the outer and/or inner surface of the radome (up to hundreds of µC/m2) shell leads to a multivariance of the mechanisms of development of discharge processes inside the radome model, along its surface, and in the space near it. Significant influence of the “reverse” discharge from the antenna model under the radome on the types of current impulses recorded on the antennas under impact of the artificial thunderstorm cell is established. Peculiarities of the discharge formation in the radome model when using solid and segmented diverter strips for its protection are revealed. Parameters of the current impulses registered on the diverter strips and the antennas have been determined. Based on the conducted research, the possible mechanisms of the impact of thunderclouds and lightning discharges on radio-transparent aircraft radomes and the equipment inside them are considered.

Radial current distribution along the ionization wave propagating in a long dielectric capillary tube filled with a low-pressure helium

The experimental results on the study of the ionization wave propagating along a long capillary tube are presented. The ionization wave was initiated by high-voltage pulse of positive or negative polarity. The propagation of this surface ionization wave precedes and influences the establishment of complete electric breakdown within the tube. The spreading of this wave is accompanied by the surface charge deposition. The usage of the fine-sectioned outer electrode allows one to find out the general features of the ionization waves.

Artificial Negative Polarity Thunderstorm Cell Modeling of Nearby Incomplete Upward Discharges’ Influence on Elements of Monitoring Systems for Air Transmission Lines

The article represents results of a physical simulation of incomplete upward leader discharges induced on air transmission lines’ elements, using charged artificial thunderstorm cells of negative polarity. The influence of such discharges on closely located model sensors (both of rod and elongated types) of digital monitoring systems, as well as on the models of receiver-transmission systems of local data collection (antennas), was determined. Effect of heterogeneity of electromagnetic field caused by incomplete upward discharges on frequency specter of signals generated on sensors and antennas was estimated. Wavelet analysis was carried out to determine the basic frequency diapasons of such signals. Based on experimental data obtained, suppositions about the extent of influence of nearby incomplete leader discharges on the functioning of currently used systems of transmission lines’ monitoring were made.

Minimizer negative polarity items in non-negative contexts

Minimizer strong NPIs such as ˋˋlift a finger'' are known to be more restricted in their occurrence than weak NPIs like ˋˋever''. Sedivy 1990 points to contexts with a ˋˋnegative side message'' in which ˋˋlift a finger'' can occur but ˋˋever'' cannot. The paper provides a short overview over the relevant contexts and proposes an extension of a representational theory of NPI licensing with the following components: First, an utterance content is introduced that enriches the primary truth-conditional content by conventional implicatures and generalized conversational implicatures. Second, ˋˋever''-type NPIs can be licensed by weak NPI licensors, but only in the primary truth-conditional meaning of an utterance. ˋˋLift-a-finger''-type NPIs can only be licensed in the scope of negation, but the licensing can be checked at the representation of the enriched meaning of an utterance.

Cyclic changes to the negative coordinating conjunction from Latin to Modern French

The evolution of the negative coordinating conjunction (‘neither’/‘nor’) from Latin to Modern French instantiates a type of cyclic development that is previously undocumented as such at the level of morphosyntax, viz. a ‘semasiological’ cycle. In effect, the conjunction appears to have taken an almost perfectly circular path. Thus, in Classical Latin, as is consonant with the typological status of that language as a Double Negation language, neque/nec was exclusively used in negative contexts. Medieval French being a Negative Concord language, on the other hand, its negative coordinating conjunction, ne, a direct descendant of neque/nec, was able to develop a full range of weak negative polarity uses. In a range of contexts, ne was thus semantically equivalent to either the additive conjunction et (‘and’) or the disjunction ou (‘or’). By the end of the Classical French period, however, the conjunction (which by then takes the form ny/ni) has lost all of its weak negative polarity uses again, and it is used only in strong negatively polar environments in Modern Standard French. Based on data from the electronic corpora Frantext and Base de Français Médiéval, I analyze the three stages of this evolution. I show that, together with other developments in the French negative system, it falsifies predictions made in the literature and has consequences for the reconstruction of negative systems in less well-documented languages.

Sentiment Analysis of Imran Khan’s Tweets

In the recent past, sentiment analysis has been an area of interests of psychologists, sociologists, neurologists, computer scientists, and linguists including corpus linguists and computational linguists. Interdisciplinary approaches to researching various issues especially the analysis of social media websites such as Facebook, Twitter, and Instagram are becoming popular nowadays. The availability of data on social media has made it easier to analyse the opinion or sentiments of its users. Analysis of these sentiments could reveal the face of users and it could help in various decision-making processes. Sentiment analysis is a system of knowing polarity (positive, negative, and neutral) in discourse. Moreover, sentiments can enable and disable certain functions of discourse and can divert the attention of the audience from important to a less important issue or otherwise, hence, there is a need to analyse the sentiments. In this research, sentiments (Polarity) of Imran Khan’s tweets are analysed with the help of R studio. Data for this study is collected from Imran Khan’s one-year’s tweets, tweeted from 1st January 2018 to 20th November 2018. Later we saved the data in. csv files. The results of the polarity check revealed that he has used all three types of sentiments that is positive, negative, and neutral. However, he mostly used neutral or free polarity items (FPIs) that is 67.41% in his tweets. Among positive and negative polarity items the number of negative polarity items (NPIs) is higher that is 23.21% as compared to positive polarity items (PPIs) which are only 9.40%. The manual analysis of results revealed that only software is not enough and there is a need to check the accuracy of the results manually. The use of negative polarity/negative face reveals that he tries to be independent and autonomous in his decisions (Goffman, 1967). The use of positive polarity items shows he tries to show his positive face to others. Moreover, sentiment analysis demonstrates the presence of themes propagated through the use of various lexical items.

Ion-acoustic solitary structures at the acoustic speed in a collisionless magnetized nonthermal dusty plasma

At the acoustic speed, we have investigated the existence of ion-acoustic solitary structures including double layers and supersolitons in a collisionless magnetized plasma consisting of negatively charged static dust grains, adiabatic warm ions, and nonthermal electrons. At the acoustic speed, for negative polarity, the system supports solitons, double layers, supersoliton structures after the formation of double layer, supersoliton structures without the formation of double layer, solitons after the formation of double layer whereas the system supports solitons and supersolitons without the formation of double layer for the case of positive polarity. But it is not possible to get the coexistence of solitary structures (including double layers and supersolitons) of opposite polarities. For negative polarity, we have observed an important transformation viz., soliton before the formation of double layer → double layer → supersoliton → soliton after the formation of double layer whereas for both positive and negative polarities, we have observed the transformation from solitons to supersolitons without the formation of double layer. There does not exist any negative (positive) potential solitary structures within 0 < μ < μ c (μ c < μ < 1) and the amplitude of the positive (negative) potential solitary structure decreases for increasing (decreasing) μ and the solitary structures of both polarities collapse at μ = μ c, where μ c is a critical value of μ, the ratio of the unperturbed number density of electrons to that of ions. Similarly there exists a critical value β e2 of the nonthermal parameter β e such that the solitons of both polarities collapse at β e = β e2.