A real options analysis of dual labor markets and the single labor contract

We study the optimal hiring and firing decisions of a firm under two different firing costs regulations: 1) Dual labor markets characterized by high firing costs for workers with seniority above a threshold ("permanent workers") and by low costs for "temporary workers". 2) The Single Labor Contract, a policy proposal to make firing costs increasing in seniority at the job. We focus on the option value implied by the regulations and obtain some new results: the optimal firing rule is a constant function of worker's productivity only for permanent workers. For temporary workers it varies with seniority at the job because the firm tries to keep alive the option to fire at low cost. In the Dual regulation the workers more likely to be fired are those close to become permanent. On the contrary, the Single Contract transfers that maximum firing to the new hires. Thus, fired workers are fired sooner under the Single Contract. However, if both regulations have the same average firing cost for workers who become permanent, temporary workers are less likely to be fired in the Single Contract. Moreover, this new regulation increases hiring and average employment duration. It also reduces turnover among temporary workers, but at the expense of higher turnover among permanent workers who are more often replaced by temporary workers.Real Options, Dual Labor, Single Contract

Fertility and Consumption when Having a Child is a Risky Investment

This paper studies children as a risky asset associated to an investment option. Children provide utility but have a stochastic maintenance cost. We obtain several new results relative to models where children are deterministic goods, among which: i) Higher child risks diminish fertility and consumption. ii) Risk aversion speeds up fertility as households use the safe utility derived from a child as insurance against fluctuations in consumption. iii) Fertility is increasing in the correlation between income and child cost shocks. The household is reluctant to have children when positive cost shocks come together with bad income shocks. The opposite result happens when children hedge income shocks. iv) The sign of the correlation determines whether higher income volatility speeds up or delays fertility.

A Real Options Analysis of Dual Labor Markets and the Single Labor Contract

We study the optimal hiring and firing decisions of a firm under two different firing costs regulations: 1) Dual labor markets characterized by high firing costs for workers workers". 2) The Single Labor Contract, a policy proposal to make firing costs increasing in seniority at the job. We focus on the option value implied by the regulations and obtain some new results: the optimal firing rule is a constant function of workerÂ’s productivity only for permanent workers. For temporary workers it varies with seniority at the job because the firm tries to keep alive the option to fire at low cost. In the Dual regulation the workers more likely to be fired are those close to become permanent. On the contrary, the Single Contract transfers that maximum firing to the new hires. Thus, fired workers are fired sooner under the Single Contract. However, if both regulations have the same average firing cost for workers who become permanent, temporary workers are less likely to be fired in the Single Contract. Moreover, this new regulation increases hiring and average employment duration. It also reduces turnover among temporary workers, but at the expense of higher turnover among permanent workers who are more often replaced by temporary workers.

Intensity-modulated stereotactic radiosurgery for arteriovenous malformations: guidance for treatment planning.

BackgroundStereotactic Radiosurgery (SRS) is a common tool used to treat Arteriovenous Malformations (AVMs) in anatomical locations associated with a risk of surgical complications. Despite high rates of clinical effectiveness, SRS carries a risk of toxicity as a result of radiation injury to brain tissue. The use of intensity-modulated radiotherapy (IMRT) has increased because it may lead to improved PTV conformity and better Normal Tissue (NT) sparing compared to 3D Conformal Radiotherapy (3DCRT). The aim of this study was twofold: 1) to develop simple patient stratification rules for the recommendation of IMRT planning strategies over 3DCRT in the treatment of AVMs with SRS; and 2) to estimate the impact of IMRT in terms of toxicity reduction using retrospectively reported data for symptomatic radiation injury following SRS.MethodsThirty-one AVM patients previously treated with 3DCRT were replanned in a commercial treatment planning system using 3DCRT and static gantry IMRT with identical beam arrangements. The radiotherapy planning metrics analyzed included AVM volume, diameter, and volume to surface area ratio. The dosimetric endpoints analyzed included conformity index improvements and NT sparing measured by the maximum NT dose, and the volume of surrounding tissue that received 7Gy and 12Gy.ResultsOur analysis revealed stratified subsets of patients for IMRT that were associated with improved conformity, and those that were associated with decreased doses to normal tissue. The stratified patients experienced an improvement in conformity index by -6-68%, a reduction in the maximum NT dose by -0.5-12.3%, a reduction in the volume of NT receiving 7Gy by 1-8 cc, and a reduction in the volume of NT receiving 12Gy by 0-3.7 cc. The reduction in NT receiving 12Gy translated to a theoretical decrease in the probability of symptomatic injury by 0-9.3%.ConclusionsThis work indicates the potential for significant patient improvements when treating AVMs and provides rules to predict which patients are likely to benefit from IMRT

Clinically relevant investigation of flattening filter-free skin dose

As flattening filter-free (FFF) photon beams become readily available for treatment delivery in techniques such as SBRT, thorough investigation of skin dose from FFF photon beams is necessary under clinically relevant conditions. Using a parallel-plate PTW Markus chamber placed in a custom water-equivalent phantom, surface-dose measurements were taken at 2 × 2, 3 × 3, 4 × 4, 6 × 6, 8 × 8, 10 × 10, 20 × 20, and 30 × 30 cm2 field sizes, at 80, 90, and 100 cm source-to-surface distances (SSDs), and with fields defined by jaws and multileaf collimator (MLC) using multiple beam energies (6X, 6XFFF, 10X, and 10XFFF). The same set of measurements was repeated with the chamber at a reference depth of 10 cm. Each surface measurement was normalized by its corresponding reference depth measurement for analysis. The FFF surface doses at 100 cm SSD were higher than flattened surface doses by 45% at 2 × 2 cm2 to 13% at 20 × 20 cm2 for 6 MV energy. These surface dose differences varied to a greater degree as energy increased, ranging from +63% at 2 × 2 cm2 to -2% at 20 × 20 cm2 for 10 MV. At small field sizes, higher energy increased FFF surface dose relative to flattened surface dose; while at larger field sizes, relative FFF surface dose was higher for lower energies. At both energies investigated, decreasing SSD caused a decrease in the ratios of FFF-to-flattened surface dose. Variability with SSD of FFF-to flattened surface dose differences increased with field size and ranged from 0% to 6%. The field size at which FFF and flattened beams gave the same skin dose increased with decreasing beam energy. Surface dose was higher with MLC fields compared to jaw fields under most conditions, with the difference reaching its maximum at a field size between 4 × 4 cm2 and 6 × 6 cm2 for a given energy and SSD. This study conveyed the magnitude of surface dose in a clinically meaningful manner by reporting results normalized to 10 cm depth dose instead of depth of dose maximum