Retirement and Home Production: A Regression Discontinuity Approach

Existing studies show that individuals who retire replace some private consumption by home production, but do not consider joint behaviour of couples. Here we analyze the causal effect of retirement of each partner on hours of home production of both partners in a couple. Our identification strategy exploits the earliest age retirement laws in France, enabling a fuzzy regression discontinuity approach. We find that own retirement significantly increases own hours of home production and the effect is larger for men than for women. Moreover, retirement of the female partner significantly reduces male hours of home production but not vice versa.time allocation, house work, couples

Does Income Taxation Affect Partners' Household Chores?

We study the impact of income taxation on both partners' allocation of time to market work and unpaid house work in households with two adults. We estimate a structural household utility model in which the marginal utilities of leisure and house work of both partners are modelled as random coefficients, depending on observed and unobserved characteristics of the household and the two partners. We use a discrete choice model with choice sets of 2,401 points for each couple, distinguishing seven market work intervals and seven house work intervals for each partner. The model is estimated using data for France, which taxes incomes of married couples jointly, like, for instance, Germany and the US. We find that both partners’ market and non-market time allocation decisions are responsive to changes in the tax system or other policy changes that change the financial incentives. Women's time allocation is more responsive to the own and the partner’s wage rate than men's. Tax policy simulations suggest that moving from joint taxation for married couples to separate taxation of each spouse would go a small step in the direction of equalizing market and non-market work of spouses. Selective taxation with smaller tax rates for women than for men would magnify these effects.time use, taxation, labour supply, discrete choice models

Complementarity, impatience, and the resilience of natural-resource-dependent economies

We study how human preferences aect the resilience of economies that depend on more than one type of natural resources. In particular, we analyze whether the degree of substitutability of natural resources in consumer needs may give rise to multiple steady states and path dependence even when resources are managed optimally. This is a major shift in the interpretation and analysis of resilience, from viewing (limited) resilience as an objective property of the economy-environment system to acknowledging its partially subjective, preference-based character. We nd that society tends to be less willing to buer exogenous shocks if resource goods are complements in consumption than if they are substitutes. Hence, the stronger the complementarity between the various types of resource goods, the less resilient the economy is.Resilience; substitutes and complements; discounting; multiple steady states; natural resources; path dependence; regime shifts; tipping points

Global gene expression profiling of ischemic preconditioning in the rat retina

PURPOSE: To obtain and analyze the gene expression changes after ischemic preconditioning (IPC) in the rat retina. METHODS: Ischemic damage to the inner retina can be prevented by a short, non-deleterious, ischemic insult of 5 min applied 24 h preceding a full ischemic insult of 60 min; a phenomenon termed tolerance or IPC. The time course of changes in gene expression after induction of IPC was assessed by 22K oligonucleotide microarrays, followed by real-time quantitative polymerase chain reaction (qPCR) validation. Functional pathways of interest were identified by Gene Ontology-term analysis. RESULTS: Histology confirmed that IPC induction by 5 min of retinal ischemia results in a complete protection against the neurodegenerative effects of a 60 min ischemic period applied 24 or 48 h later. The microarray analysis revealed differential expression of 104 known genes at one or more time points between 1 h and 7 days after IPC. The group of altered genes contained a significant overrepresentation of genes involved in aminoacyl-tRNA synthetase activity (Iars, Lars, Cars, Yars, Gars, Tars), amino acid transport (Slc3a2, Slc6a6, Slc7a1, Slc38a2), regulation of transcription (including Egr1, Egr4, Nr4a1, Nr4a3, c-fos), and cell death (including Anxa1, Trib3). qPCR assays on cDNA of individual animals confirmed the microarray results. CONCLUSIONS: Endogenous neuroprotection, provoked by ischemic preconditioning is associated with changes in transcript levels of several functionally-related groups of genes. During the time window of effective protection, transcript levels of genes encoding for aminoacyl-tRNA synthetases and for amino acid transport are reduced. These changes suggest that a reduction of translational activity may play a significant role in preconditioning-mediated neuroprotectio

The effect of klapskate hinge position on push-off performance: a simulation study

klapskate in speed skating confronts skaters with the question of how to adjust the position of the hinge in order to maximize performance. The purpose of this study was to reveal the constraint that klapskate hinge position imposes on push-off performance in speed skating. Method: For this purpose, a model of the musculoskeletal system was designed to simulate a simplified, two-dimensional skating push off. To capture the essence of a skating push off, this model performed a one-leg vertical jump, from a frictionless surface, while keeping its trunk horizontally. In this model, klapskate hinge position was varied by varying the length of the foot segment between 115 and 300 mm. With each foot length, an optimal control solution was found that resulted in the maximal amount of vertical kinetic and potential energy of the body’s center of mass at take off (Weff). Results: Foot length was shown to considerably affect push-off performance. Maximal Weff was obtained with a foot length of 185 mm and decreased by approximately 25 % at either foot length of 115 mm and 300 mm. The reason for this decrease was that foot length affected the onset and control of foot rotation. This resulted in a distortion of the pattern of leg segment rotations and affected muscle work (Wmus) and the efficacy ratio (Weff/Wmus) of the entire leg system. Conclusion: Despite its simplicity, the model very well described and explained the effects of klapskate hinge position on push off performance that have been observed in speed-skating experiments. The simplicity of the model, however, does not allow quantitative analyses of optimal klapskate hinge position for speed-skating practice. Key Words: SPEED SKATING, SPORTS EQUIPMENT, LOCOMOTION, MUSCULO-SKELETAL MODEL, BIOMECHANICS Klapskates have become the custom equipment inspeed skating. In contrast to the conventionalskates, in which the shoe is rigidly fixed to th

Optimizing the Distribution of Leg Muscles for Vertical Jumping.

A goal of biomechanics and motor control is to understand the design of the human musculoskeletal system. Here we investigated human functional morphology by making predictions about the muscle volume distribution that is optimal for a specific motor task. We examined a well-studied and relatively simple human movement, vertical jumping. We investigated how high a human could jump if muscle volume were optimized for jumping, and determined how the optimal parameters improve performance. We used a four-link inverted pendulum model of human vertical jumping actuated by Hill-type muscles, that well-approximates skilled human performance. We optimized muscle volume by allowing the cross-sectional area and muscle fiber optimum length to be changed for each muscle, while maintaining constant total muscle volume. We observed, perhaps surprisingly, that the reference model, based on human anthropometric data, is relatively good for vertical jumping; it achieves 90% of the jump height predicted by a model with muscles designed specifically for jumping. Alteration of cross-sectional areas-which determine the maximum force deliverable by the muscles-constitutes the majority of improvement to jump height. The optimal distribution results in large vastus, gastrocnemius and hamstrings muscles that deliver more work, while producing a kinematic pattern essentially identical to the reference model. Work output is increased by removing muscle from rectus femoris, which cannot do work on the skeleton given its moment arm at the hip and the joint excursions during push-off. The gluteus composes a disproportionate amount of muscle volume and jump height is improved by moving it to other muscles. This approach represents a way to test hypotheses about optimal human functional morphology. Future studies may extend this approach to address other morphological questions in ethological tasks such as locomotion, and feature other sets of parameters such as properties of the skeletal segments

A method for the deliberate and deliberative selection of policy instrument mixes for climate change adaptation

Policy instruments can help put climate adaptation plans into action. Here, we propose a method for the systematic assessment and selection of policy instruments for stimulating adaptation action. The multi-disciplinary set of six assessment criteria is derived from economics, policy, and legal studies. These criteria are specified for the purpose of climate adaptation by taking into account four challenges to the governance of climate adaptation: uncertainty, spatial diversity, controversy, and social complexity. The six criteria and four challenges are integrated into a step-wise method that enables the selection of instruments starting from a generic assessment and ending with a specific assessment of policy instrument mixes for the stimulation of a specific adaptation measure. We then apply the method to three examples of adaptation measures. The method’s merits lie in enabling deliberate choices through a holistic and comprehensive set of adaptation specific criteria, as well as deliberative choices by offering a stepwise method that structures an informed dialog on instrument selection. Although the method was created and applied by scientific experts, policy-makers can also use the method

Real-time volumetric lipid imaging in vivo by intravascular photoacoustics at 20 frames per second

Lipid deposition can be assessed with combined intravascular photoacoustic/ultrasound (IVPA/US) imaging. To date, the clinical translation of IVPA/US imaging has been stalled by a low imaging speed and catheter complexity. In this paper, we demonstrate imaging of lipid targets in swine coronary arteries in vivo, at a clinically useful frame rate of 20 s−1. We confirmed image contrast for atherosclerotic plaque in human samples ex vivo. The system is on a mobile platform and provides real-time data visualization during acquisition. We achieved an IVPA signal-to-noise ratio of 20 dB. These data show that clinical translation of IVPA is possible in principle

Simultaneous Morphological and Flow Imaging Enabled by Megahertz Intravascular Doppler Optical Coherence Tomography

We demonstrate three-dimensional intravascular flow imaging compatible with routine clinical image acquisition workflow by means of megahertz (MHz) intravascular Doppler Optical Coherence Tomography (OCT). The OCT system relies on a 1.1 mm diameter motorized imaging catheter and a 1.5 MHz Fourier Domain Mode Locked (FDML) laser. Using a post processing method to compensate the drift of the FDML laser output, we can resolve the Doppler phase shift between two adjoining OCT A-line datasets. By interpretation of the velocity field as measured around the zero phase shift, the flow direction at specific angles can be qualitatively estimated. Imaging experiments were carried out in phantoms, micro channels, and swine coronary artery in vitro at a speed of 600 frames/s. The MHz wavelength sweep rate of the OCT system allows us to directly investigate flow velocity of up to 37.5 cm/s while computationally expensive phase-unwrapping has to be applied to measure such high speed using conventional OCT system. The MHz sweep rate also enables a volumetric Doppler imaging even with a fast pullback at 40 mm/s. We present the first simultaneously recorded 3D morphological images and Doppler flow profiles. Flow pattern estimation and three-dimensional structural reconstruction of entire coronary artery are achieved using a single OCT pullback dataset