The Employed, the Unemployed, and the Unemployable: Directed Search with Worker Heterogeneity

We examine the implications of worker heterogeneity on the equilibrium matching process, using a directed search model. Worker abilities are selected from a general distribution, subject to some weak regularity requirements, and the firms direct their job offers to workers. We identify conditions under which some fraction of the workforce will be "unemployable": no firm will approach them even though they offer positive surplus. For large markets we derive a simple closed form expression for the equilibrum matching function. This function has constant returns to scale and two new terms, which are functions of the underlying distribution of worker productivities: the percentage of unemployable workers, and a measure of heterogeneity (?).The equilibrium unemployment rate is increasing in ? and, under certain circumstances, is increasing in the productivity of highly skilled workers, despite endogenous entry. A key empirical prediction of the theory is that ? ? 1. We examine this prediction, using data from several countries.Directed search; worker heterogeneity; unemployment

Wage Inequality in a Burdett-Mortensen World

This paper examines the development of wage inequality in the context of a Burdett- Mortensen (1998) model that is extended to incorporate worker heterogeneity through skill requirements in the production process. In this environment, wage dispersion is a natural consequence of firms pursuing different wage strategies as well as a result of worker and firm production heterogeneity. Changes in the wage distribution are then explained by changes in the productivity of heterogeneous firms. The resulting change in theoretical steady state wage distributions as a result of changes in relative productivity is consistent with many of the observed changes in distribution of wages in the US in recent decades. In particular, an increase in the productivity of less efficient firms may reduce between-group inequality while at the same time increase within-group inequality as observed during the 1970s. On the other hand, an increase in productivity of more efficient firms will tend to increase both between- and within-group inequality as observed during the 1980s and 1990s

The unemployment volatility puzzle: the role of the underground economy

Relying on the non-negligible role played by the underground economy in the labour market fluctuations, this paper extends the standard matching model à la Mortensen-Pissarides by introducing an underground sector along with an endogenous sector choice for both entrepreneurs and workers. These modifications improve the quantitative properties of the standard matching model, thus providing a possible explanation for the unemployment volatility puzzle.unemployment and vacancies volatility; productivity and job destruction shocks; underground economy; shadow economy; hidden economy; matching models.

Finite-temperature Fermi-edge singularity in tunneling studied using random telegraph signals

We show that random telegraph signals in metal-oxide-silicon transistors at millikelvin temperatures provide a powerful means of investigating tunneling between a two-dimensional electron gas and a single defect state. The tunneling rate shows a peak when the defect level lines up with the Fermi energy, in excellent agreement with theory of the Fermi-edge singularity at finite temperature. This theory also indicates that defect levels are the origin of the dissipative two-state systems observed previously in similar devices.Comment: 5 pages, REVTEX, 3 postscript figures included with epsfi

Detection of low energy single ion impacts in micron scale transistors at room temperature

We report the detection of single ion impacts through monitoring of changes in the source-drain currents of field effect transistors (FET) at room temperature. Implant apertures are formed in the interlayer dielectrics and gate electrodes of planar, micro-scale FETs by electron beam assisted etching. FET currents increase due to the generation of positively charged defects in gate oxides when ions (121Sb12+, 14+, Xe6+; 50 to 70 keV) impinge into channel regions. Implant damage is repaired by rapid thermal annealing, enabling iterative cycles of device doping and electrical characterization for development of single atom devices and studies of dopant fluctuation effects

The Loss-Processing Framework

The circumstances of responding to loss due to human death are among the most stressful experiences encountered in life. Although grief’s symptoms are typically considered essential to their gradual diminishment, possible negative impacts of complications related to grief are also well known, and have been associated with detriments to mental and physical health. Grief, however, can also generate transformative positive change. Thus, albeit ineludible, responding to loss is not uniformly experienced, expressed, or understood. It is also culturally-shaped, making attempts to define “normal” grief, as well as to label some grief “abnormal”—and to medicalize it—possibly problematic. Bereavement (the situation surrounding a death) and mourning (the publicly expressed response to loss due to death) are changing. Some of these changes (e.g., the increase in hospice care settings prior to deaths, and alterations in the ritual responses following all deaths—irrespective of their context) may have important implications for avoiding grief’s possible complications and for promoting its potential benefits. An improved alignment of grief theory, research, and practice is warranted; but theories of grief are diverse, and historically have not been empirically well-supported. This research articulates a new grief model, the loss-processing framework, featuring three dimensional components (perception, orientation, and direction). As a first step toward validation of the framework, also included is an empirical study examining retrospective descriptive reports of adult loss response relating to the first of these three dimensions (perception). As an interpretive, translational approach to understanding grief, the loss-processing framework may serve to positively impact grieving, health, and life quality

Mapping networks of influence: tracking Twitter conversations through time and space

The increasing use of social media around global news events, such as the London Olympics in 2012, raises questions for international broadcasters about how to engage with users via social media in order to best achieve their individual missions. Twitter is a highly diverse social network whose conversations are multi-directional involving individual users, political and cultural actors, athletes and a range of media professionals. In so doing, users form networks of influence via their interactions affecting the ways that information is shared about specific global events. This article attempts to understand how networks of influence are formed among Twitter users, and the relative influence of global news media organisations and information providers in the Twittersphere during such global news events. We build an analysis around a set of tweets collected during the 2012 London Olympics. To understand how different users influence the conversations across Twitter, we compare three types of accounts: those belonging to a number of well-known athletes, those belonging to some well-known commentators employed by the BBC, and a number of corporate accounts belonging to the BBC World Service and the official London Twitter account. We look at the data from two perspectives. First, to understand the structure of the social groupings formed among Twitter users, we use a network analysis to model social groupings in the Twittersphere across time and space. Second, to assess the influence of individual tweets, we investigate the ageing factor of tweets, which measures how long users continue to interact with a particular tweet after it is originally posted. We consider what the profile of particular tweets from corporate and athletes’ accounts can tell us about how networks of influence are forged and maintained. We use these analyses to answer the questions: How do different types of accounts help shape the social networks? and, What determines the level and type of influence of a particular account

“Certainly Getting About the World”: New Zealanders’ Experience of the Middle East as a Place During the Second World War

New Zealand’s longest and most important campaign of the Second World War was in the Middle East. When New Zealand’s Middle Eastern war is discussed, the focus is usually on combat and the lives of New Zealanders on the battlefield. The limited discussion of life behind the lines is dominated by a picture of racism, drunkenness and debauchery with its focal point in Cairo. This article uses primary sources, including diaries, letters and soldier publications, and focusses on how New Zealanders saw the Middle East as a place, through the lenses of the desert, the city, the Holy Land and the ancient world. An examination of these topics reveals a complex and rich picture of respect and loathing, delight and disgust, wonder and disillusionment. Such a picture shows that the one-dimensional understanding of racism and poor behaviour is an entirely inadequate representation of New Zealanders’ Middle Eastern war

Photoinduced Temperature Gradients in Sub-wavelength Plasmonic Structures: The Thermoplasmonics of Nanocones

Plasmonic structures are renowned for their capability to efficiently convert light into heat at the nanoscale. However, despite the possibility to generate deep sub-wavelength electromagnetic hot spots, the formation of extremely localized thermal hot spots is an open challenge of research, simply because of the diffusive spread of heat along the whole metallic nanostructure. Here we tackle this challenge by exploiting single gold nanocones. We theoretically show how these structures can indeed realize extremely high temperature gradients within the metal, leading to deep sub-wavelength thermal hot spots, owing to their capability of concentrating light at the apex under resonant conditions even under continuous wave illumination. A three-dimensional Finite Element Method model is employed to study the electromagnetic field in the structure and subsequent thermoplasmonic behaviour, in terms of the three-dimensional temperature distribution. We show how the latter is affected by nanocone size, shape, and composition of the surrounding environment. Finally, we anticipate the use of photoinduced temperature gradients in nanocones for applications in optofluidics and thermoelectrics or for thermally induced nanofabrication