Phase Diagram of Bosons in Two-Color Superlattices from Experimental Parameters

We study the zero-temperature phase diagram of a gas of bosonic 87-Rb atoms in two-color superlattice potentials starting directly from the experimental parameters, such as wavelengths and intensities of the two lasers generating the superlattice. In a first step, we map the experimental setup to a Bose-Hubbard Hamiltonian with site-dependent parameters through explicit band-structure calculations. In the second step, we solve the many-body problem using the density-matrix renormalization group (DMRG) approach and compute observables such as energy gap, condensate fraction, maximum number fluctuations and visibility of interference fringes. We study the phase diagram as function of the laser intensities s_2 and s_1 as control parameters and show that all relevant quantum phases, i.e. superfluid, Mott-insulator, and quasi Bose-glass phase, and the transitions between them can be investigated through a variation of these intensities alone.Comment: 4 pages, 3 figure

Performance Evaluation of Open Graded Base Course with Doweled and Non-Doweled Transverse Joints

The objectives of this study were to investigate the performance of 20-year old doweled/non-doweled and dense-graded/permeable base test sections on three concrete pavement segments in Wisconsin: USH 18/151 in Iowa and Dane counties, STH 29 in Brown County, and USH 151 in Columbia and Dane Counties. Five pavement bases were placed including: dense graded, asphalt-stabilized permeable, cement-stabilized permeable, and untreated permeable having two gradation sizes. USH 18/151 test sections had similar performance (PDI) for doweled unsealed pavement on dense and permeable base. Distresses common to all segments included slight to moderate distressed joints/cracks and slight transverse faulting. Asphalt-stabilized permeable base had no slab breakup or surface distresses, however it measured a greater severity of distressed joints and cracks. Non-doweled sections having asphalt-stabilized permeable base and Transverse Inter Channel drains had better performance and ride than the other non-doweled sections. IRI was generally higher on non-doweled pavements, but many doweled sections had an equal roughness to non-doweled sections. Sealed non-doweled joints produced a better performing pavement, however, sealant did not appear to improve ride. STH 29 unsealed sections performed better than the median PDI for the sealed sections. The sealed doweled pavement did perform a little better than the non-doweled section, but the opposite occurred on the non-doweled sections. Sealed doweled joints had a smoother ride than the other combinations. USH 151 test sections found the finer-graded New Jersey permeable base had the smoothest ride when compared to other permeable sections. Asphalt-stabilized permeable base had the roughest ride, and unstabilized and cement-stabilized permeable bases had intermediate values. The average hydraulic conductivity for the unstabilized permeable base was 17,481 feet per day and there appears little variation due to doweling or joint sealant. Deflection load transfer results indicate expected high average values for the doweled sections and fair to poor values for the non-doweled sections. Slab support ratios indicate variable results based on base type and joint reinforcement/sealant. Life-cycle cost analysis found dense-graded base was the least cost among all base alternatives, with a total estimated present-worth life-cycle cost of $665,133 per roadway mile. Untreated and asphalt-stabilized permeable bases were more expensive by 13% and 27%, respectively. Other factors in selecting dense-graded base over permeable base include project drainage conditions set forth in the FDM guidelines an anticipated increase in pavement surface roughness

Social Position and Distributive Justice: Experimental Evidence

Using a simple, double-blind dictator experiment, we examine the extent to which subjects\u27 choices of distributive shares are influenced by unearned social position. We measure social position by the initial distributive shares (resources) and the subjects\u27 ability to determine the final distributive shares (power). We find that subjects\u27 decisions are consistent with Rawls\u27 (1971) hypothesis that individuals expect a greater share when in a position with more power and initial resources. Finally, we test if subjects\u27 choices under a laboratory veil of ignorance are consistent with Rawls\u27 concept of distributive justice. Veiled individuals exhibit preferences that are less risk-averse and have greater variance than Rawls hypothesized. [excerpt

Additive and synergistic relations of early mother-child and caregiver-child interactions for predicting later achievement.

This study examines associations between stimulating-responsive social interactions with mothers and nonparental childcare providers during the first 3 years of life and children's vocabulary and mathematics skills through age 15 (N = 1,364). Additive relations were found in which more stimulating-responsive interactions with mothers and with caregivers were linked to higher mathematics achievement in childhood and adolescence. More stimulating-responsive early interactions with mothers were also associated with larger child vocabularies through age 15. Synergistic relations, consistent with the dual-risk hypothesis, also were found. Children whose early interactions with both mothers and caregivers were low in stimulation and responsivity had substantially lower mathematics skills. Implications for early childhood interventions and policies are discussed. (PsycINFO Database Record (c) 2019 APA, all rights reserved)

An Experimental Study of the Holdout Problem in a Multilateral Bargaining Game

When an economic exchange requires agreement by multiple independent parties, the potential exists for an individual to strategically delay agreement in an attempt to capture a greater share of the surplus created by the exchange. This holdout problem is a common feature of the land-assembly literature because development frequently requires the assembly of multiple parcels of land. We use experimental methods to examine holdout behavior in a laboratory bargaining game that involves multi-person groups, complementary exchanges, and holdout externalities. The results of six treatments that vary the bargaining institution, number of bargaining periods, and cost of delay demonstrate that holdout is common across institutions and is, on average, a payoff-improving strategy for responders. Both proposers and responders take a more aggressive initial bargaining stance in multi-period bargaining treatments relative to single-period treatments, but take a less aggressive bargaining stance when delay is costly. Nearly all exchanges eventually occur in our multi-period treatments, leading to higher overall efficiency relative to the single-period treatments, both with and without delay costs. [excerpt

Ultracold Bose gases in time-dependent 1D superlattices: response and quasimomentum structure

The response of ultracold atomic Bose gases in time-dependent optical lattices is discussed based on direct simulations of the time-evolution of the many-body state in the framework of the Bose-Hubbard model. We focus on small-amplitude modulations of the lattice potential as implemented in several recent experiment and study different observables in the region of the first resonance in the Mott-insulator phase. In addition to the energy transfer we investigate the quasimomentum structure of the system which is accessible via the matter-wave interference pattern after a prompt release. We identify characteristic correlations between the excitation frequency and the quasimomentum distribution and study their structure in the presence of a superlattice potential.Comment: 4 pages, 4 figure

Multi-Period Rent-Seeking Contests with Carryover: Theory and Experimental Evidence

The majority of theoretical and experimental research stemming from Tullock’s (1980) model of rent-seeking considers static, single-period contests. This paper contributes to a growing body of research on multi-period rent-seeking contests by developing and experimentally testing a model in which a player’s effort affects the probability of winning a contest in both the current and future periods. Theory predicts that rent-seeking effort will be shifted forward from later to earlier periods, with no change in overall rent-seeking expenditures relative to the static contest. Experimental results indicate a significant shift forward when “carryover” is present and that the amount shifted is directly related to the carryover rate. Finally, although experimental expenditures are greater than the equilibrium predictions, overall rent-seeking effort in the carryover contests is lower than in similar static contests.

Personality Preferences and Pre-Commitment: Behavioral Explanations in Ultimatum Games

This paper uses responder pre-commitment and the Jungian theory of mental activity and psychological type, as measured by the widely-used Myers-Briggs Type Indicator (MBTI), to gain insight into subject behavior in a laboratory ultimatum bargaining experiment. Three experiment design details are noteworthy: (1) one design requires responders to make a nonbinding pre-commitment rejection level prior to seeing the offer, (2) one design requires responders to make a binding pre-commitment rejection level, and (3) one design includes a third person (or “hostage”) who makes no decision, but whose payment depends on the proposal being accepted. In general, we find behavior in our experiment to be consistent with hypotheses based on theoretical underpinnings of the MBTI and its descriptions of psychological type.

An Experimental Study of the Holdout Problem in a Multilateral Bargaining Game

When an economic exchange requires agreement by multiple independent parties, the potential exists for an individual to strategically delay agreement in an attempt to capture a greater share of the surplus created by the exchange. This “holdout problem” is a common feature of the land assembly literature because development frequently requires the assembly of multiple parcels of land. We use experimental methods to examine holdout behavior in a laboratory bargaining game that involves multi-person groups, complementary exchanges, and holdout externalities. The results of six treatments that vary the bargaining institution, number of bargaining periods, and the cost of delay demonstrate that holdout is common across institutions and is, on average, a payoff-improving strategy for responders. Both proposers and responders take a more aggressive initial bargaining stance in multi-period bargaining treatments relative to single-period treatments, but take a less aggressive bargaining stance when delay is costly. Nearly all exchanges eventually occur in our multi-period treatments, leading to higher overall efficiency relative to the single-period treatments, both with and without delay costs.