Although no pattern on the physical aspects of project leaders appears to exist, there are some patterns of actions that relate to the "soft" side of project management.
Warren Opfer, Timothy Kloppenborg, and Arthur Shirberg, although not discarding the need for technical and administrative skills, note that project leadership requires strength in interpersonal skills, negotiation, and conflict management. 
Greg Skulmoski, Francis Hartman, and Roch DeMaere conducted a study on traits of project managers according to the different roles played . The authors note two types of competencies of project managers: threshold and superior competencies. Threshold competencies require completing tasks at a minimum and acceptable level. Superior competencies are those above others from a performance perspective.
The authors found that many soft skills populated both competencies. It was the threshold competencies, however, that were quite instructive including creativity, open communication, proactivity, decisiveness, trust, judgment, delegation, results oriented, and achievement drive. 
Their conclusions? They found that project managers needed competencies in areas like open communication and trust as well as in decisiveness and delegation. 
Dean Sitiriou and Dennis Wittmer conducted a study of project managers based on previous studies from 1974 onward. In their study, they noted that respondents rated negotiation, personality, and persuasive ability as very important, followed by competence for surmounting the authority gap that project managers often face. 
In an interview in PM Network , Daniel Goleman, co-author of Primal Leadership , stated that emotional intelligence determines a leader's success or failure because the soft skills, e.g., self-awareness and empathy, are the determining ingredient. He noted in the interview that his research of leaders in approximately 500 organizations found that EI had a 2 to 1 success ratio, but for project managers it was much higher. 
Horst Bergmann, Kathleen Hurson, and Darlene Russ-Eft conducted a study of about 1,800 "incidents" of leadership among nonsupervisory employees , not project managers per se. They note that "grass roots leaders" harness and control their emotions, such as self-management , self-reflection, and positivity. 
Keane, a major consulting company, developed what is known as the Project Manager Competency Model (PMCM), which identifies clusters of project management skills and behavior. These are:
Achievement cluster ” consisting of concern for achievement, results orientation, initiative, and business acumen
Influence cluster ” consisting of organizational and interpersonal astuteness, skillful use of influence strategies, team building, development of others, client/ user orientation, and self-control
Managerial identity cluster ” consisting of project manager identity, self-confidence , and flexibility
Problem-solving cluster ” consisting of diagnostic thinking, systematic thinking, conceptual thinking, and monitoring information gathering
Although there does not appear to be one overriding cluster, the article that describes the PMCM observed that the two attributes that appeared to have importance were the ability to negotiate and manage conflict. 
Albert Einsiedel observed that project managers must have five qualities to lead effectively: credibility, creative problem solving, tolerance for ambiguity, flexible management style, and communication skills. 
Barry Posner observed that project managers had the following attributes, behaviors, and techniques in descending order: communication, planning, team building, leadership, coping, and technological skills. 
Interestingly, Posner took a somewhat narrow view of leadership, observing that it consists of characteristics like setting the example, being energetic , and positive. A strong case, however, can be made that some other skills, such as communication, team building, and coping, can be subsumed under leadership as it has for other studies. If that is the case, then the technological and administrative type skills are outnumbered by a greater factor.
 Warren A. Opfer, Timothy J. Kloppenborg, and Arthur Shirberg, Project leadership ” setting the stage, in Proceedings of PMI Research Conference 2002 , Project Management Institute, Newtown Square, PA, p. 417.
 Greg Skulmoski, Francis Hartman, and Roch DeMaere, Superior and threshold competencies, Project Management , 6(1), 13, 2000.
 Greg Skulmoski, Francis Hartman, and Roch DeMaere, Superior and threshold competencies, Project Management , 6(1), 13, 2000. p. 14.
 Dean Sitiriou and Dennis Wittmer, Influence methods of project managers: perceptions of team members and project managers, Project Management Journal , p. 19, September 2001.
 Jeannette Cabanis-Brewin, The human task of a project leader, PM Network , pp. 38 “41, November 1999.
 Horst Bergmann, Kathleen Hurson, and Darlene Russ-Eft, Introducing a grass-roots model of leadership, Strategy & Leadership , pp. 15 “20, October-December 1999.
 Jim Edgemon, Right stuff: how to recognize it when selecting a project manager, Application Development Trends , pp. 37 “42, May 1995.
 Albert A. Einsiedel, Profile of effective project managers, in Leadership Skills for Project Managers , Jeffrey K. Pinto and Jeffrey W. Trailer, Eds., Project Management Institute, Newtown Square, PA, 1998, pp. 4 “6.
 Barry Posner, What it takes to be a good project manager, in Leadership Skills for Project Managers , Jeffrey K. Pinto and Jeffrey W. Trailer, Eds., Project Management Institute, Newtown Square, PA, 1998, p. 13.