Positive Leader Research Articles

Modeling of natural first stroke stepped leader characteristics

The paper constitutes a novel physical approach to the different stages of negative leader stepping in cloud-to-ground lightning, starting with determination of the length of the negative streamer zone below the leader tip. The positive space leader, belonging to a pre-existing space leader, propagates towards the main leader tip, bridging the streamer zone. Such propagation time however is too short for leader thermalization. The thermalization, with associated substantial drop in the internal voltage gradient, occurs over a much longer time, through corona current injected at the tip of the moving negative space leader. The latter stage constitutes the determining factor for the time interval between steps. The model has then been applied to leaders with prospective return stroke current of 3–228 kA, leader tip height of 23–2000 m, leader charge linearly decaying to practically vanish at heights of either 2500 m or 4500 m. For the conditions investigated, the step length varies in the range 3.5 m to 39 m, the bridging time of the streamer zone by positive space leader in the range 0.8 - 3 μs, time interval between steps in the range 8.5–92 μs, yielding mean stepped leader speed in the range 1.0 - 11.6 × 105 m/s. Whenever possible the model predictions were satisfactorily compared to field measurements. Interaction between the negative downward leader and an upward connecting leader during the attachment process is out of scope of this work.

Does the Scenario of Connection Between the Positive Leader Tip and the Lateral Surface of the Negative Leader Exist?

AbstractBased on the high‐speed video observations obtained at the Tall‐Object Lightning Observatory in Guangzhou (TOLOG), the attachment processes of three lightning flashes seem to belong to the connections between “the lateral surface of negative leader and positive leader tip” which had never been reported before were investigated. The leader connection processes of these flashes were examined in detail, and a mechanism behind connecting behavior between the lateral surface of negative leader and positive leader tip was discussed. Observation shows that negative leaders usually have abundant branches. Although some may extinguish, they still maintain a certain conductivity. When the positive leader tip comes close to the lateral surface of the negative leader (usually a few tens of meters), the previously disappeared short branch can be reactivated. It is easier for the positive leader tip to connect the tips of these branches (whether they have been extinguished or not).

Positive Leadership Development and Leadership Types in Finnish Leaders’ Narratives

This study focused on Finnish leaders who participated in a training program called “Positive Leadership Training”. The purpose of this study was to enhance the general understanding regarding the emergence of positive leadership in leaders, as they themselves described. A narrative research approach was chosen, and the data were collected from leaders’ diaries (N = 12) that they maintained and updated during the training program. The analysis of narratives and narrative analysis were conducted. The analysis of the narratives was divided into four categories, each representing the way leaders described the emergence and development of their positive leadership. While some leaders described strong empowerment, others seemed to be searching for their own identities as positive leaders. Furthermore, leaders also described positive leadership in terms of action, and deliberation and courage were the core categories in their leadership narratives. The narrative analysis revealed the following four leadership types: humane thinker, enthusiastic developer, courageous experimentalist, and identity worker, typifying the variations between empowered and emerging leadership narratives and between prudence and the active execution of leadership. The results highlighted the role of authenticity in leadership development and the benefits of positive leadership training for leaders with different backgrounds.

Initiation of Downward Positive Leader Beneath the Negative Leader Channel

AbstractDue to the weak radiation generated by positive leaders, our understanding of how positive leaders are initiated and reach the ground remains limited. This study investigated positive cloud‐to‐ground (CG) lightning induced after the long intracloud lightning based on high‐speed video and fast antenna mapping results. Below the cloud base in the field of view, re‐breakdowns of decayed negative branches occurred consecutively beneath the horizontal negative channel in the form of bidirectional leaders. These bidirectional leaders advanced along the same channel, and eventually, the third reached the ground, generating a positive return stroke (RS) with a peak current of 157 kA. Following the RS, new negative discharges emerge adjacent to the vertical return stroke channel, persisting and propagating to form a continuing current (CC) lasting over 200 milliseconds.

Electromagnetic Model of K‐Changes

AbstractK‐changes are observed as step‐like increases in the thundercloud electric fields. The K‐changes occur in the late part of intra‐cloud lightning or during negative cloud‐to‐ground lightning between return strokes. It has been shown that the processes leading to K‐changes initiate in the decayed part of a positive leader channel and propagate toward the flash origin. They are often accompanied by microsecond‐scale electric field pulses. We introduce a new model to simulate processes leading to the K‐changes in cloud‐to‐ground lightning. Our method is based on the full solution of Maxwell's equations coupled to Poisson's equation for the thundercloud charge structure. To model the K‐changes, we gradually increase the decayed channel conductivity. The modeled current wavefront propagates due to the K‐processes downward along a vertical channel and completely attenuates before reaching the ground. We derive the evolution of the linear charge densities and the scalar electric potential along the channel leading to K‐changes. We model electrostatic step‐like changes in the measured electric field together with the approximate rates and amplitudes of the microsecond scale pulses. Step‐like changes increase their amplitudes with the length of the simulated channel and with a higher conductivity of the channel. The microsecond‐scale pulse waveshapes depend mainly on the propagation velocity of the current wave, and the time scale of the conductivity increase. We show that our modeled waveforms are in a good agreement with observations conducted in Florida.

Evaluating Exercise as Punishment: Insights from the Delphi Method on Philippine School Practices

Abstract The study aimed to identify consensus among PE experts on using exercise as punishment (EAP) in Philippine schools. The study adopted a two-round Delphi method. In the first round, a survey with open-ended questions prompted experts to identify as many reasons as possible for the use of EAP in schools. This format gave the experts a more significant role in responding, as they could identify crucial themes related to EAP usage and then refine them into meaningful categories. The second round of the survey asked the experts to rank these identified factors based on their perceived importance. Based on the experts’ agreement, “EAP as a disciplinary tool” was ranked as the most significant dimension in the use of EAP in schools. Further factors impacting its use, including social pressure, physical health benefits, its connection to establishing authority, academic performance, athletic performance, and a lack of understanding about alternative disciplinary measures, were also identified. Despite its documented harms, the use of EAP persists in Philippine schools. This study reveals a complex web of drivers, including a persistent belief in EAP’s disciplinary effectiveness, external pressures for “tough” approaches, and a lack of awareness of positive alternatives. These factors create a cycle of conformity in which student well-being could suffer. To break this cycle, schools must prioritize fostering positive teacher-student relationships, equipping teachers, leaders, and staff with effective disciplinary strategies, and challenging misguided narratives around EAP’s supposed merits.

Effect of the negative-end discharge on the positive leader propagation in bidirectional leader discharges

Lightning strikes on aircraft are mainly due to self-triggered bidirectional leader discharges. Understanding the physical processes of lightning strikes is the basis for designing appropriate lightning protection measures. For this purpose, the development processes of bidirectional leaders triggered by a floating conductor were studied in a laboratory. In this paper, an experimental platform for the observation of bidirectional leader discharges is established through a reasonable gap arrangement. The discharge processes were recorded by a high-speed camera with up to 504 000 f/s. The effects of negative streamer discharges on the positive leader propagation speed as well as brightness during the bidirectional leader discharge at different electric field rise rates were mainly studied and quantitatively analyzed by introducing incremental coefficients. The experimental results show that the discharge development at the negative end of the floating conductor lags behind that at the positive end, and there is a coupling phenomenon between the positive and the negative discharge. At low electric field rise rates, when a negative streamer discharge occurs, it causes a positive corona burst, resulting in a sharp increase in brightness, while on the contrary the leader speed change is not as pronounced as the brightness change. As the rate of rise of the electric field increases, the effect of the discharge at the negative end on the positive end gradually decreases. This work could provide a theoretical basis for understanding the physical process of lightning strikes on aircraft.

Do Islamic work ethics matter? Impact of aversive leadership on employees’ emotional and psychological health through the lens of conservation of resource theory

Aversive leadership remains a relatively underexplored area in organizational behavior. This study advances the field by identifying emotional exhaustion as a key mechanism linking aversive leadership to employees’ psychological health outcomes, including psychological well-being, psychological strain, and psychological detachment. It also examines the role of Islamic work ethics (IWE) as a moderator in the relationship between aversive leadership and emotional exhaustion. Supported by conservation of resource (COR) theory, which posits that stressful workplace situations, such as aversive leadership, lead to resource depletion resulting in emotional exhaustion and poor psychological health, this study finds that individuals with strong personal resources, such as IWE, are better equipped to cope with these negative outcomes. Data were collected from 260 employees in service sector organizations of Pakistan using self-administrated questionnaires. The results supported direct and indirect effects, as well as the moderating role of IWE. This study provides valuable insights for policymakers in addressing the negative impacts of aversive leadership and offers organizations guidance on selecting and nurturing supportive and positive leaders. Such leaders can foster a healthier and more productive work environment.

Observation and analysis of positive leader re-illumination in a 10 m ultra-high voltage transmission line gap under switching impulse voltages

The leader propagation is one of the most important stages in long air gap discharge. The mechanism behind leader re-illumination remains unclear. In high humidity conditions (20.0–30.1 g/m³), we have conducted experiments of long sparks in a 10 m ultra-high voltage (UHV) transmission line gap under switching impulse voltages. The positive leaders predominantly propagate discontinuously, with almost no significantly continuous propagation occurring. The leader channels are intensely luminous and each elongation segment is straight, with streamers resembling the “branch type” which differs from the “diffuse type” streamers at the front of continuous propagation leaders. The distribution of the propagation velocities is highly random (3.7–18.4 cm/μs), and the average velocity (9.2 cm/μs) significantly exceeds that of continuous propagation (1.5–2.0 cm/μs). Analysis suggests that the current-velocity models suitable for continuous leader propagation do not align well with the experimental data in re-illumination mode. Based on the discharge current waveforms and optical images, it is speculated that the newly elongated leader in re-illumination mode does not evolve gradually from the stem (about 1 cm) but rather evolves overall from a thermal channel much longer than stem.

Teaching Core Values through Physical Activity Using a Tangible Item

To foster positive youth development (PYD), sport organizations, programs, coaches, and program leaders should use holistic youth development in a pro-social manner and provide a nurturing climate. This article offers an idea for a tangible way to promote PYD in sport and physical activity settings via a patch system.

Subordinate-to-supervisor relational identification: A meta-analytic review.

Although subordinate-to-supervisor relational identification (RI) has gained significant scholarly attention in organizational research, an understanding of its nomological network is incomplete. There have also been recurring discussions about its distinctions with another more extensively researched relational construct-leader-member exchange (LMX). In this meta-analysis, we expand Sluss and Ashforth's (2007) typology, going beyond the influence of the supervisor, to systematically study the antecedents and consequences of RI and its comparison with LMX. Meta-analytic results based on 157 independent samples demonstrate that positive leader behaviors that span role-based and person-based identities (e.g., transformational leadership, supervisor humility) are important antecedents of subordinate-to-supervisor RI, with effects contingent on subordinates' national culture (i.e., collectivism and power distance). Although less hypothesized, relational and organizational contexts as well as subordinate characteristics are also important antecedents of subordinate-to-supervisor RI. The results further show that RI relates to important subordinate behaviors and attitudes. Finally, we test how RI and LMX have differing effects across these important subordinate attitudes and behaviors. We conclude with suggestions to enhance our understanding of RI. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Attachment processes of negative flashes with multiple return strokes to a tall tower observed at close distances

Two downward negative flashes (F1612 & F1613) with multiple return strokes struck to the 356-m Shenzhen Tower were analyzed. The high-speed camera captured upward positive connecting leaders (UCL) for the first strokes of both flashes and two subsequent strokes of F1612. The observations also show that none of the downward negative leader (DNL) completely propagated to the tower tip before the occurrence of the return stroke (RS), so that we inferred that the UCL initiated from the tower tip might exist for each RS of the two flashes. The possible height of the UCL and DNL connecting point above the tower tip for each RS was estimated, which showed a positive correlation to the speed of corresponding DNL. The striking distances estimated for 8 subsequent RSs in F1612 were in a range from 14.6 m to 85.4 m and that for 3 subsequent RSs in F1613 were from 24.2 m to 66.2 m. There was a weak positive linear relationship between the DNL speed and striking distance for subsequent RSs in the two flashes. The DNL speed showed a positive correlation to the peak current of corresponding RS.

Numerical simulation of reversal point dynamics in intracloud lightning: Back-and-forth promoting effect

Lightning is a self-developing charge transport system that exhibits fundamental manifestations of the macro-scale polarity asymmetry. This asymmetry is tightly connected with peculiarities of the reversal point (the point of zero leader sheath charge or, alternatively, a site where the lightning channel potential coincides with the intracloud one) movement along the leader growth direction. The study presents a stochastic lightning discharge model that is used to analyze the reversal point dynamics. It is shown that the reversal point shifts towards the direction of growth of the dominant leader, i.e. the leader with prevailing peripheral current. The cases of upward and downward directions of the positive leader propagation are considered to study how the difference in altitudes of positive and negative lightning poles influences the mode of reversal point drift. The model predicts that, for the case of an intracloud lightning, the amplitudes of oscillation of reversal point altitude and voltage are of the order of 1 km and 100 MV, respectively, with the reversal point voltage change rate being of the order of 10 MV/ms. The results allow to conclude that the reversal point meandering is a fundamental manifestation of lightning evolution.

Evolution of the Leader Discharge in Bi‐Directional Propagation System in Altitude‐Triggered Lightning

AbstractOn 18 June 2023, comprehensive observations were conducted to an altitude‐triggered lightning flash. Upward positive leader (UPL) and downward negative leader (DNL) in a bi‐directional development system were detected simultaneously by a high‐speed camera, together with the coordinated measurements of magnetic field and very‐high‐frequency (VHF) emissions. High‐speed images reveal, for the first time, the enhancement of the UPL's propagation speed by DNL in the bi‐directional leader system. Concretely, the upward positive leader initially originates from a suspended wire tip and propagates at a two dimensional (2D) speed of 5.32 × 104 m/s, and after about 6.3 ms, its propagation speed was enhanced to 1.12 × 105 m/s when the stepped DNL started advancing at an average speed of 1.44 × 105 m/s. Additionally, based on the evolution of channel luminosity and the variations of magnetic radiation, it is found that there is a consistency in luminosity variation between the ascending channel and the descending channel in the bi‐directional leader system, and the amplitude of the magnetic field increases when the negative discharges start at the bottom wire end with intensive VHF emissions. Those facts indicate that the DNL has an effect, may be a positive one, on the UPL's development in the early stage of altitude‐triggered lightning.

Humidity Effects on the Positive Leader Steps in Laboratory Long Spark Discharges

AbstractThe stepwise development of positive lightning leaders is still not well understood. A recent laboratory study indicated, at high absolute humidity, positive leaders can do steps due to the merging of a separate luminous structure and the primary leader channel, similar to the steps of negative leaders. The humidity may play a key role in the formation of positive leader steps, however, the humidity effect on the positive leader steps has never been explored. In this paper, we examine numerous positive long spark discharges at different humidity levels with the synchronized discharge current and high‐speed camera frames recording the evolution of leader channel. The positive leader propagation manners at different humidity levels are compared both morphologically and electrically. The effect of humidity on steps is further analyzed statistically. We found that the positive leader steps characterized by steep‐rise current pulse and abrupt channel elongation, which may be led by separate luminous structures, only appear under the condition that high absolute humidity is above a certain threshold. As the ambient humidity increases, these positive leader steps occur more frequently.

FDTD Simulation of a Small‐Scale Charged Airplane Model in an Ambient Electric Field between Two Flat Electrodes

When an airplane flies in an electric field under a thundercloud, electric fields at the edges and projected portions of the airplane are enhanced and leaders emanate from there. When a positive leader emanating upward from the airplane connects with a downward negative leader from the bottom of an ordinary thundercloud and a negative leader emanating downward from the airplane connects with an upward positive leader from the ground, a large lightning current flows along the channel bridged between the thundercloud and the ground through the airplane. Recently, a method to reduce the risk of lightning strikes to airplanes has been proposed. It controls the charge on the surface of an airplane to suppress the electric field at edges and projected portions of the airplane. In this paper, an airplane under a thundercloud is represented with a vertical conducting bar or a horizontal conducting bar with a small projected portion, which is placed between impulse‐high‐voltage‐applied two flat electrodes, and it is analyzed using the finite‐difference time‐domain (FDTD) method. Corona and leader discharges emanating from edges and projected portions of an airplane model are considered with their engineering representations: 40‐μS/m and 0.02 S/m conducting regions for corona and leader discharges, respectively. The airplane model is not pre‐charged or pre‐charged negatively. It follows from the FDTD‐computed results that pre‐charging an airplane model with a relevant amount of negative charge can avoid discharges from and to the airplane model. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Effects of Applied Voltage on Branching of Positive Leaders in Laboratory Long Sparks

AbstractPositive leaders branch less frequently than negative counterpart, and the physical processes and properties of positive leader branching remain a mystery. We investigated 10 m laboratory discharges under four positive voltages using a high‐speed video camera. Positive leaders differ from negative leaders by either directly splitting or connecting with floating bidirectional leaders to form branching, and the number of leader branches shows a positive correlation with the applied voltage, that is, the branched channels increased from 1 to 4 when the voltage increased by a factor of 1.5. Grounding points are positioned beneath the electrode and are more concentrated with lower voltage. During the stable progression of the leader, there is a slight increase in its development speed as the applied voltage rises. When the voltage is increased by 70%, the average breakdown time decreases by 40%. These characteristics provide insights into the branching mechanism of positive leaders.

Timing Is Everything: An Imprinting Framework for the Implications of Leader Emotional Expressions for Team Member Social Worth and Performance

Leader emotional expressions have profound implications for team members. Research has established that how frequently leaders express positive and negative emotional expressions shapes team member performance through conveying critical social-functional information about team member social worth. Yet, this social-functional approach to emotions has not fully considered how the timing of leader emotional expressions during a team’s lifecycle can also shape the information conveyed to individual team members about their social worth. In this paper, we integrate the social-functional approach to emotions with imprinting theory to propose that the temporal context of leader emotional expressions has performance implications for individual team members through two distinct facets of social worth: respect and status. Specifically, our imprinting framework explains how positive leader emotional expressions during the early team phase have the most beneficial performance implications through imprinting respect in individual team members. We then propose that these positive implications are amplified by more frequent than average negative leader emotional expressions during the midpoint phase. When filtered through earlier positive expressions, negative emotional expressions during the midpoint phase may signal opportunities for respect and status gains rather than respect and status losses. We find general support for our model in a pre-registered four-wave longitudinal archival study of consulting teams at a leading professional services company and a four-wave longitudinal field study at a NCAA Division 1 sports program. Our work highlights that the temporal context of leader emotional expressions is an important performance predictor through social worth.

Observations of very unusual behavior of lightning discharges

Based on recent observations at the Lightning Observatory in Gainesville (LOG), Florida, we present three examples of very unusual behavior of cloud-to-ground (CG) lightning flashes: (a) One +CG and one tower-terminated -CG separated by 11 km, were briefly coupled, so that positive charge was in effect drawn from the ground at the position of –CG and injected into the ground at the position of +CG. That unusual interaction was accomplished by the initiation of M-component incident wave in the +CG channel by the leader of the first stroke of the –CG. (b) A branched positive leader intermittently extended via bidirectional transients separated by inactive intervals of about 5 ms, on average. One of the bidirectional transients, moving negative charge in the backward direction, triggered a downward negative leader, resulting in a three-stroke –CG. (c) A subsequent-stroke negative leader, moving through virgin air, entered the lower part of residual (non-luminous) first-stroke channel, in addition to creating a new ground termination about 950 m away. Studying unusual lightning behavior helps to improve our understanding of the variability of basic lightning processes and to identify new potential lightning hazards to various objects and systems.

Leading the Leader: Positive and Resilient Leadership (PRL) in Urban Public Schools through Filipino Public-School Teachers’ Metaphorical Perspectives

Positive leadership and resilient leadership are two types of leadership that share several commonalities, both of which seemingly respond and offer suitability to the unpredictable and volatile landscape and requirements of the times. While separately, there has been substantial empirical work on positivity and resilience in leadership, no study has been undertaken to combine both so that one type of leadership, i.e. Positive and Resilient Leadership (PRL), can emerge. Further, positivity and resilience in leadership have so far remained understudied among public organizations, particularly in urban public schools, a sector that considers ineffective leadership as among the major problems that hinder the quality of public education. Also, while previous studies have focused on such leadership from the perspective of school leaders, there remains a dearth of literature on understanding it from the standpoint of those being led, such as the teachers. To fill these gaps, this study examined the possible nature and characteristics of PRL by employing qualitative content analysis and thematic analysis in an attempt to (a) determine the metaphors Filipino teachers in urban schools use to describe leadership that is both positive and resilient, (b) identify how these metaphors capture the traits of positive and resilient school leaders in these schools, and (c) explore various situational practices of PRL in the Philippine urban public school sector. Findings showed five (5) categorizations of metaphors that were drawn from the responses of the public school teachers, indicating how PRL can provide them P.O.W.E.R., i.e. positivity, opportunity, wisdom, empathy, and reinforcement in six (6) aspects of school management, namely: (a) planning and implementation of school policies, programs, activities, and projects, (b) decision-making, (c) personnel management, (d) implementation of innovation and change, (e) resource generation and utilization, and (f) communication within and outside the organization that could improve urban public school teachers performance and well-being.