You can't take it with you: asset run-down at the end of the life cycle

This article presents evidence on the extent to which households run down their assets after retirement. The authors show that, once corrections are made for several econometric problems, households engage in very little asset decumulation after retirement.Retirement ; Income ; Wealth

Women and the Phillips curve: do women’s and men’s labor market outcomes differentially affect real wage growth and inflation?

During the economic expansion of the 1990s, the United States enjoyed both low inflation rates and low levels of unemployment. Juhn, Murphy, and Topel (2002) point out that the low unemployment rates for men in the 1990s were accompanied by historically high rates of non-employment suggesting that the 1990s economy was not as strong as the unemployment rate might indicate. We include women in the analysis and examine whether the Phillips curve relationships between real compensation growth, changes in inflation, and labor market slackness are the same for men and women and whether measures of “non- employment” better capture underlying economic activity, as suggested by Juhn, Murphy, and Topel’s analysis. From 1965 to 2002 the increase in women’s labor force participation more than offsets the decline for men, and low unemployment rates in the 1990s were accompanied by historically low overall non- employment rates. We find that women’s measures of labor market slackness do as well as men’s in explaining real compensation growth and changes in inflation after 1983. We also find some evidence that non-employment rates are more closely related to changes in inflation than other measures of labor market slackness; however, we do not find the same for real compensation growth.Labor market ; Phillips curve ; Wages ; Inflation (Finance)

Skill Specialization and the Formation of Collaboration Networks

Problem solving and innovation are important in many contexts, including academic research, policy-making, product development, and entrepreneurship. Broadly speaking, innovators come in two varieties: specialists and generalists. Specialists are people who have a deep knowledge of a very narrow subject area. Generalists are people whose knowledge ranges across multiple subject areas. In this paper, I examine the role of skill specialization in collaboration network structure, and individual position in the collaborative community. Using a model of skill specialization and collaboration network formation, I show that as disci- plines become less insular, the collaboration network becomes increasingly domi- nated by a small number of individuals. I compare specialists and generalists with the same number of skills and show that specialists will tend to have more links in the network than generalists with the same number of skills. However, I the show that generalists are more likely than specialists to occupy key central positions in the network

Nature, Culture and Big Old Trees: Human Relationships With Ceiba (Ceiba Pentandra) and Live Oak (Quercus Virginiana) in the Landscapes of Guatemala and Louisiana.

The ceiba in Guatemala and the live oak in Louisiana are examples of two trees that attain great size and age within the cultural landscape. Humans have adopted both as symbolic trees; they protect, encourage and even plant them. As the trees age, they become historic landmarks, are indicators of important places, and give character to the landscape. Although each tree is native within portions of each study area, both have taken advantage of human disturbance to expand beyond their original habitats. In addition, they have been moved deliberately by humans to new areas well beyond their geographical limits. Other parallels include their presence in places like schools, public parks and plazas, along roadsides, in sacred places and in front of government buildings. The stories of how they came to prominence, however, are different. The ceiba was the tree of life among the ancient Maya. It has survived conquest to become the national tree of Guatemala. The live oak\u27s importance in Louisiana\u27s landscape developed rapidly in the last 150 years and is in part the result of European attitudes toward Old World oaks transferred to a New World species. Examining the everyday interactions and landscape roles of the trees reveals that while the ceiba is a formal, public tree, live oaks are often planted on private land and treated as individuals, even given human names. Other differences include the far more specialized care given to live oaks, their economic value as aesthetic objects, and their planting in large groups. Despite their differences, both trees are examples of untamed, wild creatures placed deliberately in the center of the built environment. Their physical presence and symbolic significance exert a strong influence on the experience of place. Human relationships with big old trees challenge the usual distinction between wild and domesticated species, emphasizing the importance of understanding the ongoing interaction that shapes the lived-in landscape. They suggest the unity rather than the separation of nature and culture

Identifying components of the hair-cell interactome involved in cochlear amplification

<p>Abstract</p> <p>Background</p> <p>Although outer hair cells (OHCs) play a key role in cochlear amplification, it is not fully understood how they amplify sound signals by more than 100 fold. Two competing or possibly complementary mechanisms, stereocilia-based and somatic electromotility-based amplification, have been considered. Lacking knowledge about the exceptionally rich protein networks in the OHC plasma membrane, as well as related protein-protein interactions, limits our understanding of cochlear function. Therefore, we focused on finding protein partners for two important membrane proteins: Cadherin 23 (cdh23) and prestin. Cdh23 is one of the tip-link proteins involved in transducer function, a key component of mechanoelectrical transduction and stereocilia-based amplification. Prestin is a basolateral membrane protein responsible for OHC somatic electromotility.</p> <p>Results</p> <p>Using the membrane-based yeast two-hybrid system to screen a newly built cDNA library made predominantly from OHCs, we identified two completely different groups of potential protein partners using prestin and cdh23 as bait. These include both membrane bound and cytoplasmic proteins with 12 being <it>de novo </it>gene products with unknown function(s). In addition, some of these genes are closely associated with deafness loci, implying a potentially important role in hearing. The most abundant prey for prestin (38%) is composed of a group of proteins involved in electron transport, which may play a role in OHC survival. The most abundant group of cdh23 prey (55%) contains calcium-binding domains. Since calcium performs an important role in hair cell mechanoelectrical transduction and amplification, understanding the interactions between cdh23 and calcium-binding proteins should increase our knowledge of hair cell function at the molecular level.</p> <p>Conclusion</p> <p>The results of this study shed light on some protein networks in cochlear hair cells. Not only was a group of <it>de novo </it>genes closely associated with known deafness loci identified, but the data also indicate that the hair cell tip link interacts directly with calcium binding proteins. The OHC motor protein, prestin, also appears to be associated with electron transport proteins. These unanticipated results open potentially fruitful lines of investigation into the molecular basis of cochlear amplification.</p

Specialists and Generalists: Equilibrium Skill Acquisition Decisions in Problem-solving Populations

Many organizations rely on the skills of innovative individuals to create value, including academic and government institutions, think tanks, and knowledge-based firms. Roughly speaking, workers in these fields can be divided into two categories: specialists, who have a deep knowledge of a single area, and generalists, who have knowledge in a wide variety of areas. In this paper, I examine an individual's choice to be a specialist or generalist. My model addresses two questions: first, under what conditions does it make sense for an individual to acquire skills in multiple areas, and second, are the decisions made by individuals optimal from an organizational perspective? I find that when problems are single-dimensional, and disciplinary boundaries are open, all workers will specialize. However, when there are barriers to working on problems in other fields, then there is a tradeoff between the depth of the specialist and the wider scope of problems the generalist has available. When problems are simple, having a wide variety of problems makes it is rational to be a generalist. As these problems become more difficult, though, depth wins out over scope, and workers again tend to specialize. However, that decision is not necessarily socially optimal--on a societal level, we would prefer that some workers remain generalists

Cell-specific activity-dependent fractionation of layer 2/3→5B excitatory signaling in mouse auditory cortex

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Neuroscience 35 (2015): 3112-3123, doi:10.1523/JNEUROSCI.0836-14.2015.Auditory cortex (AC) layer 5B (L5B) contains both corticocollicular neurons, a type of pyramidal-tract neuron projecting to the inferior colliculus, and corticocallosal neurons, a type of intratelencephalic neuron projecting to contralateral AC. Although it is known that these neuronal types have distinct roles in auditory processing and different response properties to sound, the synaptic and intrinsic mechanisms shaping their input–output functions remain less understood. Here, we recorded in brain slices of mouse AC from retrogradely labeled corticocollicular and neighboring corticocallosal neurons in L5B. Corticocollicular neurons had, on average, lower input resistance, greater hyperpolarization-activated current (Ih), depolarized resting membrane potential, faster action potentials, initial spike doublets, and less spike-frequency adaptation. In paired recordings between single L2/3 and labeled L5B neurons, the probabilities of connection, amplitude, latency, rise time, and decay time constant of the unitary EPSC were not different for L2/3→corticocollicular and L2/3→corticocallosal connections. However, short trains of unitary EPSCs showed no synaptic depression in L2/3→corticocollicular connections, but substantial depression in L2/3→corticocallosal connections. Synaptic potentials in L2/3→corticocollicular connections decayed faster and showed less temporal summation, consistent with increased Ih in corticocollicular neurons, whereas synaptic potentials in L2/3→corticocallosal connections showed more temporal summation. Extracellular L2/3 stimulation at two different rates resulted in spiking in L5B neurons; for corticocallosal neurons the spike rate was frequency dependent, but for corticocollicular neurons it was not. Together, these findings identify cell-specific intrinsic and synaptic mechanisms that divide intracortical synaptic excitation from L2/3 to L5B into two functionally distinct pathways with different input–output functions.This work was supported by National Institutes of Health grants DC013272 (T.T. and G.M.G.S.), DC007905 (T.T.), NS061963 (G.M.G.S), R03DC012585 (J.W.M.), T32DC011499 (C.T.A.), and F32DC013734 (C.T.A), and by the Albert and Ellen Grass Faculty Award (T.T. and G.M.G.S.) and Charles Evans Foundation Award (T.T. and G.M.G.S.).2015-08-1

Evidence of Silica Leakage to the Tropical Atlantic via Antarctic Intermediate Water during Marine Isotope Stage 4

Antarctic Intermediate Water (AAIW) and Subantarctic Mode Water (SAMW) are the main conduits for the supply of dissolved silica (silicic acid) from the deep Southern Ocean to the low latitude surface ocean, and therefore have an important control on low latitude diatom productivity. Enhanced supply of silicic acid by AAIW (and SAMW) during glacial periods may have enabled tropical diatoms to outcompete carbonate-producing phytoplankton, decreasing the relative export of inorganic to organic carbon to the deep ocean and lowering atmospheric CO2. This mechanism is known as the 'Silicic Acid Leakage Hypothesis' (SALH). Here we present records of neodymium and silicon isotopes from the western tropical Atlantic that provide the first direct evidence of increased silicic acid leakage from the Southern Ocean to the tropical Atlantic within AAIW during glacial Marine Isotope Stage (MIS) 4 (~60-80 ka). This leakage is coeval with enhanced diatom export in the NW Atlantic and across the eastern equatorial Atlantic and provides support for the SALH as a contributor to CO2 drawdown during full glacial development