Dynamics on the Way to Forming Glass: Bubbles in Space-time

We review a theoretical perspective of the dynamics of glass forming liquids and the glass transition. It is a perspective we have developed with our collaborators during this decade. It is based upon the structure of trajectory space. This structure emerges from spatial correlations of dynamics that appear in disordered systems as they approach non-ergodic or jammed states. It is characterized in terms of dynamical heterogeneity, facilitation and excitation lines. These features are associated with a newly discovered class of non-equilibrium phase transitions. Equilibrium properties have little if anything to do with it. The broken symmetries of these transitions are obscure or absent in spatial structures, but they are vivid in space-time (i.e., trajectory space). In our view, the glass transition is an example of this class of transitions. The basic ideas and principles we review were originally developed through the analysis of idealized and abstract models. Nevertheless, the central ideas are easily illustrated with reference to molecular dynamics of more realistic atomistic models, and we use that illustrative approach here.Comment: 21 pages, 8 figures. Submitted to Annu. Rev. Phys. Che

Understanding antibiotic use: practices, structures and networks.

In this article, we consider how social sciences can help us to understand the rising use of antibiotics globally. Drawing on ethnography as a way to research how we are in the world, we explore scholarship that situates antibiotic use in relation to interactions of pathogens, humans, animals and the environment in the context of globalization, changes in agriculture and urbanization. We group this research into three areas: practices, structures and networks. Much of the public health and related social research concerning antimicrobial resistance has focused on antibiotic use as a practice, with research characterizing how antibiotics are used by patients, farmers, fishermen, drug sellers, clinicians and others. Researchers have also positioned antibiotic use as emergent of political-economic structures, shedding light on how working and living conditions, quality of care, hygiene and sanitation foster reliance on antibiotics. A growing body of research sees antibiotics as embedded in networks that, in addition to social and institutional networks, comprise physical, technical and historical connections such as guidelines, supply chains and reporting systems. Taken together, this research emphasizes the multiple ways that antibiotics have become built into daily life. Wider issues, which may be invisible without explication through ethnographic approaches, need to be considered when addressing antibiotic use. Adopting the complementary vantage points of practices, networks and structures can support the diversification of our responses to AMR

An efficient semiparametric maxima estimator of the extremal index

The extremal index $\theta$, a measure of the degree of local dependence in the extremes of a stationary process, plays an important role in extreme value analyses. We estimate $\theta$ semiparametrically, using the relationship between the distribution of block maxima and the marginal distribution of a process to define a semiparametric model. We show that these semiparametric estimators are simpler and substantially more efficient than their parametric counterparts. We seek to improve efficiency further using maxima over sliding blocks. A simulation study shows that the semiparametric estimators are competitive with the leading estimators. An application to sea-surge heights combines inferences about $\theta$ with a standard extreme value analysis of block maxima to estimate marginal quantiles.Comment: 17 pages, 7 figures. Minor edits made to version 1 prior to journal publication. The final publication is available at Springer via http://dx.doi.org/10.1007/s10687-015-0221-

Vertical integration in production and services: development in transaction cost economics

In this paper, we first establish the core, fundamental concepts of Williamson's TCE, examining the different governance structures or the institutional alternatives that TCE theory proposes. We go on to describe some critical considerations and theoretical proposals that correspond fundamentally to Williamson's heuristic model, the integration of incentives in organizational forms, idiosyncratic demand, and how the concept of transaction is conceived in general.Peris-Ortiz, M.; Bonet, F.; Rueda Armengot, C. (2011). Vertical integration in production and services: development in transaction cost economics. Service Business. 5(1):87-97. doi:10.1007/s11628-011-0103-0S879751Alchian A (1965) The basic of some recent advances in the theory of management of the firm. J Ind Econ 14:30–41Alchian A (1969) Corporate management and property rights. In: Manne GH (ed) Economic Policy and Regulation of Corporate Securities. American Enterprise Institute of Public Policy Research, Washington, DCAlchian A, Demsetz H (1972) Production, information cost, and economic organization. Am Econ Rev 62:777–795Arrow KJ (1959) Toward a theory of price adjustment. In: Abramovitz M et al (eds) The allocation of resources. Stanford University Press, Stanford, CA, pp 41–51Arrow KJ (1973) Information and economic behaviour. Federation of Swedish Industries, StockholmArrow KJ (1974) The limits of organizations. W. W. Norton, New YorkBain J (1956) Barriers to new competition. Harvard University Press, Cambridge, MABain J (1958) Industrial organization, 2nd edn. John Wiley & Sons, New YorkBarnard CI (1938) The functions of the executive. Cambridge University Press, Cambridge, MAChandler AC Jr. (1962) Strategy and structure. MIT Press, Cambridge, MAChandler AC Jr. (1977) The visible hand. Harvard University Press, Cambridge, MACoase RH (1937) The nature of the firm. Economica 4:386–405Coase RH (1972) Industrial organization: a proposal for research. In: Victor RF (ed) Policy issues and research opportunities in industrial organization. National Bureau of Economic Research, New York, pp 59–73Coase RH (1991) The institutional structure of production. Prize Lecture to the Memory of Alfred Nobel, December 9, 1991, http://www.nobel.se/economics/laureates/1991/coase-lecture.htmlCyert RM, March JG (1963) A behavioural theory of the firm. Prentice-Hall, Englewood Cliffs, NJDemsetz H (1967) Toward a theory of property rights. Am Econ Rev 57:347–359Demsetz H (1991) The theory of the firm revisited. In: Williamson O, Winter S (eds) The nature of the firm: origins, evolution, and development. Oxford University Press, New York, pp 159–178Galbraith JR (1993) The value-adding corporation: matching structure with strategy. In: Galbraith JR, Lawler III EE and Associates (eds) Organizing for the future. Jossey-Bass Publishers, San Francisco, pp 15–42Li J-M, Yang J-S, Wu HH (2009) Analysis of competence differences among frontline employees from various service typologies. Serv Ind J 29(12):1763–1778Ouchi WG (1979) A conceptual framework for the design of organizational control mechanism. Manag Sci 25(9):833–848Ouchi WG (1980) Markets, bureaucracies, and clans. Admin Sci Q 25:120–142Palmer M, Owens M, De Kervenoael R (2010) Paths of the least resistance: understanding how motives form in international retail joint venturing. Serv Ind J 30(6):965–989Robinson J (1933) The economics of imperfect competition. Macmillan, LondonSafón V (2009) The moderating effect of the technological level of industry on the relationship between innovation and corporate reputation. Int Entrep Manag J 5(4):515–526Simon HA (1947) Administrative behavior. Macmillan, New YorkSimon HA (1962) The architecture of complexity. Proc Am Philos Soc 106:467–482Simon HA (1973) Applying information technology to organization design. Public Admin Rev 33:268–278Un CA, Romero-Martínez AM, Montoro-Sánchez A (2009) Determinants of R&D collaboration of service firms. Serv Bus 3:373–394Warren L, Patton D, Bream D (2009) Knowledge acquisition processes during the incubation of new high technology firms. Int Entrep Manag J 5(4):481–495Williamson OE (1975) Markets and hierarchies: analysis and antitrust implication. Free Press, New YorkWilliamson OE (1979) Transaction-cost economics: the governance of contractual relations. J Law Econ 22:3–61Williamson OE (1981) The modern corporation: origins, evolution, attributes. J Econ Lit 19:1537–1568Williamson OE (1985) The economic institutions of capitalism. Free Press, New YorkWilliamson OE (1991) Comparative economic organization: the analysis of discrete structural alternatives. Admin Sci Q 36:269–296Williamson OE (1993) Calculativeness trust and economic organization. J Law Econ 36:453–486Williamson OE (1996) The mechanisms of governance. Oxford University Press, New York, pp 250–278Williamson OE (1999) Strategy research: governance and competence perspectives. Strateg Manag J 20:1087–1108Williamson OE (2000) The new institutional economics: taking stock, looking ahead. J Econ Lit 38:595–613Williamson OE (2003) Examining economic organization through the lens of contract. Ind Corp Change 12(4):917–938Williamson OE (2005) Transaction cost economics and business administration. Scand J Manag 21:19–40Williamson OE (2008) Outsourcing: transaction cost economics and supply chain management. J Supply Chain Manag 44(2):5–16Williamson OE, Bhargava WH (1986) Assessing and classifying the internal structure and control apparatus of the modern corporation. In: Williamson OE (ed) Economic organization. Firms, markets and policy control. Wheatsheaf Books, Great Britain, Brighton, pp 54–8

Computer simulation of syringomyelia in dogs

Syringomyelia is a pathological condition in which fluid-filled cavities (syringes) form and expand in the spinal cord. Syringomyelia is often linked with obstruction of the craniocervical junction and a Chiari malformation, which is similar in both humans and animals. Some brachycephalic toy breed dogs such as Cavalier King Charles Spaniels (CKCS) are particularly predisposed. The exact mechanism of the formation of syringomyelia is undetermined and consequently with the lack of clinical explanation, engineers and mathematicians have resorted to computer models to identify possible physical mechanisms that can lead to syringes. We developed a computer model of the spinal cavity of a CKCS suffering from a large syrinx. The model was excited at the cranial end to simulate the movement of the cerebrospinal fluid (CSF) and the spinal cord due to the shift of blood volume in the cranium related to the cardiac cycle. To simulate the normal condition, the movement was prescribed to the CSF. To simulate the pathological condition, the movement of CSF was blocked

A Triple Protostar System Formed via Fragmentation of a Gravitationally Unstable Disk

Binary and multiple star systems are a frequent outcome of the star formation process, and as a result, almost half of all sun-like stars have at least one companion star. Theoretical studies indicate that there are two main pathways that can operate concurrently to form binary/multiple star systems: large scale fragmentation of turbulent gas cores and filaments or smaller scale fragmentation of a massive protostellar disk due to gravitational instability. Observational evidence for turbulent fragmentation on scales of $>$1000~AU has recently emerged. Previous evidence for disk fragmentation was limited to inferences based on the separations of more-evolved pre-main sequence and protostellar multiple systems. The triple protostar system L1448 IRS3B is an ideal candidate to search for evidence of disk fragmentation. L1448 IRS3B is in an early phase of the star formation process, likely less than 150,000 years in age, and all protostars in the system are separated by $<$200~AU. Here we report observations of dust and molecular gas emission that reveal a disk with spiral structure surrounding the three protostars. Two protostars near the center of the disk are separated by 61 AU, and a tertiary protostar is coincident with a spiral arm in the outer disk at a 183 AU separation. The inferred mass of the central pair of protostellar objects is $\sim$1 M$_{sun}$, while the disk surrounding the three protostars has a total mass of $\sim$0.30 M_{\sun}. The tertiary protostar itself has a minimum mass of $\sim$0.085 M$_{sun}$. We demonstrate that the disk around L1448 IRS3B appears susceptible to disk fragmentation at radii between 150~AU and 320~AU, overlapping with the location of the tertiary protostar. This is consistent with models for a protostellar disk that has recently undergone gravitational instability, spawning one or two companion stars.Comment: Published in Nature on Oct. 27th. 24 pages, 8 figure

Motivation and incentives of rural maternal and neonatal health care providers: a comparison of qualitative findings from Burkina Faso, Ghana and Tanzania.

In Burkina Faso, Ghana and Tanzania strong efforts are being made to improve the quality of maternal and neonatal health (MNH) care. However, progress is impeded by challenges, especially in the area of human resources. All three countries are striving not only to scale up the number of available health staff, but also to improve performance by raising skill levels and enhancing provider motivation. In-depth interviews were used to explore MNH provider views about motivation and incentives at primary care level in rural Burkina Faso, Ghana and Tanzania. Interviews were held with 25 MNH providers, 8 facility and district managers, and 2 policy-makers in each country. Across the three countries some differences were found in the reasons why people became health workers. Commitment to remaining a health worker was generally high. The readiness to remain at a rural facility was far less, although in all settings there were some providers that were willing to stay. In Burkina Faso it appeared to be particularly difficult to recruit female MNH providers to rural areas. There were indications that MNH providers in all the settings sometimes failed to treat their patients well. This was shown to be interlinked with differences in how the term 'motivation' was understood, and in the views held about remuneration and the status of rural health work. Job satisfaction was shown to be quite high, and was particularly linked to community appreciation. With some important exceptions, there was a strong level of agreement regarding the financial and non-financial incentives that were suggested by these providers, but there were clear country preferences as to whether incentives should be for individuals or teams. Understandings of the terms and concepts pertaining to motivation differed between the three countries. The findings from Burkina Faso underline the importance of gender-sensitive health workforce planning. The training that all levels of MNH providers receive in professional ethics, and the way this is reinforced in practice require closer attention. The differences in the findings across the three settings underscore the importance of in-depth country-level research to tailor the development of incentives schemes

Effect of surfactant replacement on Pneumocystis carinii pneumonia in rats

The effect of intratracheal surfactant instillation on pulmonary function in rats with Pneumocystis carinii pneumonia (PCP) was investigated. In those animals which developed PCP with severe respiratory failure after administration of cortisone acetate s. c. over 8-12 weeks, pulmonary function was improved by surfactant instillation. PaO2 values 30 min after surfactant instillation were significantly higher compared to pretreatment values and also compared to PaO2 values of rats 30 min after receiving saline (482.9 mmHg±44.7, 170.7 mmHg ±39.3 and 67.2 mmHg±17.4, respectively). Histological examination showed that alveoli of rats with PCP which received no exogenous surfactant are filled with foamy edema, whereas after exogenous surfactant alveoli are stabilized and well-aerated. These results indicate that exogenous surfactant may help patients with severe PCP to overcome an acute stage of respiratory distress

Active microrheology and simultaneous visualization of sheared phospholipid monolayers

Two-dimensional films of surface-active agents—from phospholipids and proteins to nanoparticles and colloids—stabilize fluid interfaces, which are essential to the science, technology and engineering of everyday life. The 2D nature of interfaces present unique challenges and opportunities: coupling between the 2D films and the bulk fluids complicates the measurement of surface dynamic properties, but allows the interfacial microstructure to be directly visualized during deformation. Here we present a novel technique that combines active microrheology with fluorescence microscopy to visualize fluid interfaces as they deform under applied stress, allowing structure and rheology to be correlated on the micron-scale in monolayer films. We show that even simple, single-component lipid monolayers can exhibit viscoelasticity, history dependence, a yield stress and hours-long time scales for elastic recoil and aging. Simultaneous visualization of the monolayer under stress shows that the rich dynamical response results from the cooperative dynamics and deformation of liquid-crystalline domains and their boundaries