How a "Hit" is Born: The Emergence of Popularity from the Dynamics of Collective Choice

In recent times there has been a surge of interest in seeking out patterns in the aggregate behavior of socio-economic systems. One such domain is the emergence of statistical regularities in the evolution of collective choice from individual behavior. This is manifested in the sudden emergence of popularity or "success" of certain ideas or products, compared to their numerous, often very similar, competitors. In this paper, we present an empirical study of a wide range of popularity distributions, spanning from scientific paper citations to movie gross income. Our results show that in the majority of cases, the distribution follows a log-normal form, suggesting that multiplicative stochastic processes are the basis for emergence of popular entities. This suggests the existence of some general principles of complex organization leading to the emergence of popularity. We discuss the theoretical principles needed to explain this socio-economic phenomenon, and present a model for collective behavior that exhibits bimodality, which has been observed in certain empirical popularity distributions.Comment: 17 pages, 14 figures, A version of the work is published in Econophysics and Sociophysics: Trends and Perspectives, (eds.) Bikas K. Chakrabarti, Anirban Chakraborti, Arnab Chatterjee; Wiley-VCH, Berlin (2006); Chapter-15, pages: 417-44

Isolated iliac bone tuberculosis : a case report

Background: Isolated iliac bone tuberculosis is not easy for diagnosis as it can mimic many other conditions. The presentation of our case of isolated iliac bone tuberculosis with special emphasis to imaging findings is justified, by its rarity and not uncommon delay in diagnosis and therapy of such cases. Case Report: A case of isolated iliac bone tuberculosis, initially presented with low back pain and swelling, was unsuccessfully treated for three months before final diagnosis was established. Plain radiography revealed only slight sclerosis of the iliac side of the right sacro-iliac joint. MRI provided more precise and detailed information regarding the site, size and nature of the bony and soft tissue components of the lesion. The bony lesion showed low T1, high T2 signal and marginal enhancement on fat suppressed T1 post-gadolinium images. The soft tissue components also showed post-gadolinium enhancement and abscesses formation. CT scan confirmed the bony lytic lesion and provided guidance for biopsy. Histology confirmed tuberculous nature of the lesion. Conclusions: Imaging presentation of tuberculous osteomyelitis is nonspecific and may mimic many inflammatory and neoplastic conditions. Correlation with the patient's history, immune status, ethnicity, social environment is necessary in narrowing differential diagnosis. This means that iliac tuberculosis, despite its rarity, should be considered as one of diagnostic possibilities, especially in the patients from endemic areas. However, definitive diagnosis is best established with bone needle biopsy

A Contact Stress Model for Determining Forces in an Equilibrium Grasp

Most available methods that predict the forces necessary to grasp an arbitrary object treat the object and the fingers as rigid bodies and the finger/object interface as a point contact with Coulomb friction. For statically indeterminate grasps, therefore, while it is possible to find grasps that are stable, there is no unique determination of the actual forces at the contact points and equilibrium grasps are determined as many-parameter families of solutions. Also, these models sometimes lead to phenomenologically incorrect results which, while satisfactory from a purely mathematical viewpoint, are counterintuitive and not likely to be realized in practice. The model developed here utilizes a contact-stress analysis of an arbitrarily shaped object in a multi-fingered grasp. The fingers and the object are all treated as elastic bodies and the region of contact is modeled as a deformable surface patch. The relationship between the friction and normal forces is now nonlocal and nonlinear in nature and departs from the Coulomb approximation. The nature of the constraints arising out of conditions for compatibility and static equilibrium motivated the formulation of the model as a non-linear constrained minimization problem. The total potential energy of the system is minimized, subject to the nonlinear, equality and inequality constraints on the system, using the Schittkowski algorithm. The model is able to predict the magnitude of the inwardly directed normal forces, and both the magnitude and direction of the tangential (friction) forces at each finger/object interface for grasped objects in static equilibrium. Examples in two and three dimensions are presented along with application of the model to the grasp transfer maneuver

Dimensions of human resource development: concepts and approaches

The notion of human resource development dimensions is very complicated as it has interconnections with several approaches and has involvement of variables of multiple natures. Dimension refers to the constituent elements of human resources. Different population components play different roles in the process of enhancing human capital and with a view to analyse the relative importance of them human resource development dimensions can be divided into different groups on the basis of the spatial distribution, biological, social, cultural and economic approaches. Dimensions of human resource development can be termed as quantitative and qualitative. Other approaches are human resource formation, physical and mental, rural/urban residence, spatial or territorial and composite score value approach. Therefore, this paper aims at portraying the concepts and approaches relating to different human resource development dimension with a view to make an addition to the existing knowledge in the field of geography of human resource development

DIMENSIONS OF HUMAN RESOURCE DEVELOPMENT: CONCEPTS AND APPROACHES

Abstract:   The notion of human resource development dimensions is very complicated as it has interconnections with several approaches and has involvement of variables of multiple natures. Dimension refers to the constituent elements of human resources. Different population components play different roles in the process of enhancing human capital and with a view to analyse the relative importance of them human resource development dimensions can be divided into different groups on the basis of the spatial distribution, biological, social, cultural and economic approaches. Dimensions of human resource development can be termed as quantitative and qualitative. Other approaches are human resource formation, physical and mental, rural/urban residence, spatial or territorial and composite score value approach.Therefore, this paper aims at portraying the concepts and approaches relating to different human resource development dimension with a view to make an addition to the existing knowledge in the field of geography of human resource development

Collective behavior of stock price movements in an emerging market

To investigate the universality of the structure of interactions in different markets, we analyze the cross-correlation matrix C of stock price fluctuations in the National Stock Exchange (NSE) of India. We find that this emerging market exhibits strong correlations in the movement of stock prices compared to developed markets, such as the New York Stock Exchange (NYSE). This is shown to be due to the dominant influence of a common market mode on the stock prices. By comparison, interactions between related stocks, e.g., those belonging to the same business sector, are much weaker. This lack of distinct sector identity in emerging markets is explicitly shown by reconstructing the network of mutually interacting stocks. Spectral analysis of C for NSE reveals that, the few largest eigenvalues deviate from the bulk of the spectrum predicted by random matrix theory, but they are far fewer in number compared to, e.g., NYSE. We show this to be due to the relative weakness of intra-sector interactions between stocks, compared to the market mode, by modeling stock price dynamics with a two-factor model. Our results suggest that the emergence of an internal structure comprising multiple groups of strongly coupled components is a signature of market development.Comment: 10 pages, 10 figure

Modular networks emerge from multiconstraint optimization

Modular structure is ubiquitous among complex networks. We note that most such systems are subject to multiple structural and functional constraints, e.g., minimizing the average path length and the total number of links, while maximizing robustness against perturbations in node activity. We show that the optimal networks satisfying these three constraints are characterized by the existence of multiple subnetworks (modules) sparsely connected to each other. In addition, these modules have distinct hubs, resulting in an overall heterogeneous degree distribution.Comment: 5 pages, 4 figures; Published versio

Early Results of a Modular Cementless Tibial Component for Total Knee Arthroplasty

Cementless components in TKA have been used for almost 3 decades, despite mixed success rates. However, biologic fixation remains attractive, especially for younger patients, because of the potential of unlimited durability. This paper is the first to report results on a modular tibial base plate using trabecular metal as a fixation surface. Twenty-four primary TKAs were evaluated clinical and radiographically at mean 1.9 year followup. Excellent clinical results were obtained. There was no significant subsidence or change in orientation of any component. One component was probably loose radiographically but was insufficiently symptomatic to warrant revision. Five components showed nonprogressive radiolucent lines. One reoperation was performed for stiffness, at which time the components were well fixed. Thus, it would appear that excellent bony fixation can be achieved with a modular cementless tibial component with excellent short-term clinical results

1989 Clinic Yearbook

The Clinic is the yearbook of the Sidney Kimmel Medical College (formerly Jefferson Medical College) at Thomas Jefferson University