Hybrid choice models : principles and recent progress incorporating social influence and nonlinear utility functions

AbstractHybrid choice models have been developed as an extension of discrete choice models, particularly multinomial logit models, in an attempt to include attitudinal variables. The quintessence of hybrid choice models is that a model of attitude formation is estimated and the estimated attitudes are added to the commonly used set of attributes in discrete choice models: attributes of the choice alternatives and socio-demographic variables. The most commonly applied model is based on linear specifications, both for the attitude model and the utility function. In this review paper, we discuss the principles underlying the hybrid choice model, summarize the specifications used in previous applications of the model and then continue discussing recent progress that added social influence to the model specification and replaced the linear specification of the utility function with a nonlinear function

Work schedule arrangements in two-adult households with children

The concept “work schedule arrangement” refers to the decision how many hours per week to work and how to allocate these hours across the days of the week. In two-adult households with children, the work schedule arrangement of parents is more complicated owing to the presence of children, which induces a series of activities that parents need to organize and coordinate. Besides considering personal preferences, parents also need to trade-off between working longer to generate more income and have better promotion opportunities, and working less hours to have enough time to organize and conduct other activities, especially children-related activities. In modeling work schedule arrangements of two-adult households with children, we first develop a random utility model to represent the work schedule decision-making process. It assumes that the utility of work arrangements is not only a function of work duration and other job characteristics, but also of the (joint) time to spend with or take care of the children. We therefore include the state of the children, which indicates the location where they are at any given moment in time (home, school/day care). Under the assumption that households maximize the utility derived from their work schedule, weekly work schedules for each spouse are generated, subject to observed daily and weekly total household and/or individual working hours. In order to evaluate the accuracy of the model, we compare the difference between the generated and observed work schedules of the households. The results show that the model accurately predicts observed work schedules in terms of start time, number of working hours and days of the week.</p

Dynamics of Strongly Interacting Fermi Gases of Atoms in a Harmonic Trap

Dynamics of strongly interacting trapped dilute Fermi gases is investigated at zero temperature. As an example of application we consider the expansion of the cloud of fermions initially confined in an anisotropic harmonic trap, and study the equation of state dependence of the radii of the trapped cloud and the collective oscillations in the vicinity of a Feshbach resonance.Comment: 11 pages, 3 figures. Published versio

A CD146 FACS Protocol Enriches for Luminal Keratin 14/19 Double Positive Human Breast Progenitors

Publisher's version (útgefin grein).Human breast cancer is believed to arise in luminal progenitors within the normal breast. A subset of these are double positive (DP) for basal and luminal keratins and localizes to a putative stem cell zone within ducts. We here present a new protocol based on a combination of CD146 with CD117 and CD326 which provides an up to thirty fold enrichment of the DP cells. We show by expression profiling, colony formation, and morphogenesis that CD146high/CD117high/CD326high DP cells belong to a luminal progenitor compartment. While these DP cells are located quite uniformly in ducts, with age a variant type of DP (vDP) cells, which is mainly CD146-negative, accumulates in lobules. Intriguingly, in specimens with BRCA1 mutations known to predispose for cancer, higher frequencies of lobular vDP cells are observed. We propose that vDP cells are strong candidates for tracing the cellular origin of breast cancer.We thank Lena Kristensen, Tove Marianne Lund and Anita Sharma Friismose for expert technical assistance. Benedikte Thuesen and Trine Foged Henriksen, Capio CFR Hospitaler are acknowledged for providing breast biopsy material. The Core Facility for Integrated Microscopy (University of Copenhagen) is acknowledged for confocal microscope accessibility. This work was supported by Novo Nordisk Fonden and Danish Research Council grant 10-092798 (to DanStem), Toyota-Fonden Denmark and Anita og Tage Therkelsens Fond (to R.V.), Familien Erichsens Mindefond and Vera og Carl Johan Michaelsens Legat (to J.K.), Harboefonden, Else og Mogens Wedell-wedellborgs Fond and Danish Cancer Society Grant R146-A9257 (to L.R.-J.).Peer Reviewe

Effect of paternal folate deficiency on placental folate content and folate receptor α expression in rats

We investigated the effect of paternal folate status on folate content and expression of the folate transporter folate receptor α (FRα) in rat placental tissues. Rats were mated after males were fed a diet containing 0 mg of folic acid/kg of diet (paternal folate-deficient, PD) or 8 mg folic acid/kg of diet (paternal folate-supplemented, PS) for 4 weeks. At 20 days of gestation, the litter size, placental weight, and fetal weight were measured, and placental folate content (n = 8/group) and expression of FRα (n = 10/group) were analyzed by microbiological assay and Western blot analysis, respectively. Although there was no difference observed in litter size or fetal weight, but significant reduction (10%) in the weight of the placenta was observed in the PD group compared to that in the PS group. In the PD group, placental folate content was significantly lower (by 35%), whereas FRα expression was higher (by 130%) compared to the PS group. Our results suggest that paternal folate status plays a critical role in regulating placental folate metabolism and transport

Improved Network Performance via Antagonism: From Synthetic Rescues to Multi-drug Combinations

Recent research shows that a faulty or sub-optimally operating metabolic network can often be rescued by the targeted removal of enzyme-coding genes--the exact opposite of what traditional gene therapy would suggest. Predictions go as far as to assert that certain gene knockouts can restore the growth of otherwise nonviable gene-deficient cells. Many questions follow from this discovery: What are the underlying mechanisms? How generalizable is this effect? What are the potential applications? Here, I will approach these questions from the perspective of compensatory perturbations on networks. Relations will be drawn between such synthetic rescues and naturally occurring cascades of reaction inactivation, as well as their analogues in physical and other biological networks. I will specially discuss how rescue interactions can lead to the rational design of antagonistic drug combinations that select against resistance and how they can illuminate medical research on cancer, antibiotics, and metabolic diseases.Comment: Online Open "Problems and Paradigms" articl

Three particles in an external trap: Nature of the complete J=0 spectrum

Three bosonic, spin-polarized atoms in a spherical oscillator potential constitutes the simplest nontrivial Bose-Einstein condensate (BEC). The present paper develops the tools needed to understand the nature of the complete J=0 energy spectrum for this prototype system, assuming a sum of two-body potentials. The resulting spectrum is calculated as a function of the two-body scattering length a_sc, which documents the evolution of certain many-body levels that evolve from BEC-type to molecular-type as the scattering length is decreased. Implications for the behavior of the condensate excited-state spectrum and for condensate formation and decay are elucidated. The energy levels evolve smoothly, even through the regime where the number of two-body bound states N_b increases by 1, and a_{sc} switches from -infinity to infinity. We point out the possibility of suppressing three-body recombination by tuning the two-body scattering length to values that are larger than the size of the condensate ground state. Comparisons with mean-field treatments are presented