Mechanical Property Development and Numerical Modeling of Ultra-High Performance Concrete Focused on Isothermal Curing Conditions

Ultra-high performance concrete (UHPC) has progressively gained interest because of its favorable strength and durability properties. Literature shows that curing temperature has a significant effect on the resultant mechanical properties of UHPC, generally resulting in increased compressive strength. However, limited datasets are currently available to ascertain the degree of change related to compressive strength as a function of curing temperature and conditions. This study investigates the effect of isothermal and submerged curing temperature conditions, ranging from 10°C to 90°C, on the compressive strength and elastic modulus development of UHPC and generates a numerical model to capture these effects. The extent and rate of compressive strength development in Cor-Tuf UHPC was found to increase with curing temperature, while only the rate of elastic modulus development increased with curing temperature. The numerical model shows reasonable agreement when compared with the experimental results and was successfully implemented in finite element analysis software

Physicians self selection of a payment mechanism: Capitation versus fee-for-service

The main question raised in this paper is whether GPs should self select their paymentmechanism or not. To answer it, we model GPs' behavior under the most commonpayment schemes (capitation and fee-for-service) and when GPs can select one amongthose. Our analysis considers GPs heterogeneity in terms of both ability and sense ofprofessional duty. We conclude that when savings on specialists costs are the mainconcern of a regulator, GPs should be paid on a fee-for-service basis. Instead, whenfailures to identify severe conditions are the main concern, then payment self selection byGPs can be optimal.GPs; gatekeeping; payment scheme; self selection; ability; professional duty

Provider Competition in a Dynamic Setting

In this paper, we examine provider and patient behaviour where effort is non-contractible and where competition between providers is modeled in an explicit way. More specifically, we construct a model where physicians repeatedly compete for patients and where patients’ outside options are solved for in equilibrium. In our model, physicians are characterized by an individual-specific ethical constraint which allows for unobserved heterogeneity in the physicians market. By doing so, we introduce uncertainty in the patient’s likely treatment if he were in fact to leave his current physician to seek care elsewhere. We find that competition between providers may serve as an important incentive for physicians in treating their patients with desired levels of care.Physician Payment Mechanisms, Physician heterogeneity, Competition, Information Asymmetry, Insurance.

Effect of disorder close to the superfluid transition in a two-dimensional Bose gas

We experimentally study the effect of disorder on trapped quasi two-dimensional (2D) 87Rb clouds in the vicinity of the Berezinskii-Kosterlitz-Thouless (BKT) phase transition. The disorder correlation length is of the order of the Bose gas characteristic length scales (thermal de Broglie wavelength, healing length) and disorder thus modifies the physics at a microscopic level. We analyze the coherence properties of the cloud through measurements of the momentum distributions, for two disorder strengths, as a function of its degeneracy. For moderate disorder, the emergence of coherence remains steep but is shifted to a lower entropy. In contrast, for strong disorder, the growth of coherence is hindered. Our study is an experimental realization of the dirty boson problem in a well controlled atomic system suitable for quantitative analysis

Characterization of a Quantum Light Source Based on Spontaneous Parametric Down-Conversion

We have built a quantum light source capable of producing different types of quantum states. The quantum light source is based on entangled state preparation in the process of spontaneous parametric down-conversion. The single-photon detection rate of eight-hundred thousand per second demonstrates that we have created a bright state-of-the-art quantum light source. As a part of the characterization we measured two-photon quantum interference in a Hong-Ou-Mandel interferometer.Comment: 33 page

Focusing Light through Random Photonic Media by Binary Amplitude Modulation

We study the focusing of light through random photonic materials using wavefront shaping. We explore a novel approach namely binary amplitude modulation. To this end, the light incident to a random photonic medium is spatially divided into a number of segments. We identify the segments that give rise to fields that are out of phase with the total field at the intended focus and assign these a zero amplitude, whereas the remaining segments maintain their original amplitude. Using 812 independently controlled segments of light, we find the intensity at the target to be 75 +/- 6 times enhanced over the average intensity behind the sample. We experimentally demonstrate focusing of light through random photonic media using both an amplitude only mode liquid crystal spatial light modulator and a MEMS-based spatial light modulator. Our use of Micro Electro-Mechanical System (MEMS)-based digital micromirror devices for the control of the incident light field opens an avenue to high speed implementations of wavefront shaping

An eRetailer\u27s Dilemma: The Dual Influence of Information Presentation

This study addresses the question of which information presentation format e-retailers should choose to encourage consumers to use their websites. The study proposes a model built on three conceptual foundations: the technology acceptance model (TAM), the theory of cognitive fit, and the trade-off effort-accuracy model. The model posits that consumers’ perceived cognitive effort mediates the relationship between cognitive fit and consumer perceived the perceived usefulness of the website interface for selecting the best product alternative. An online experiment was conducted with 599 e-shoppers. The results suggest that e-retailers encounter a dilemma when selecting the information presentation format for their website interface. Indeed, while cognitive fit is positively related to perceived ease of use of the website, it is negatively related to perceived effort. In turn, perceived effort is positively related to perceived usefulness conceptualized as perceived decision accuracy

Metric entropy of causal, discrete-time LTI systems

In [1] it is shown that recurrent neural networks (RNNs) can learn - in a metric entropy optimal manner - discrete time, linear time-invariant (LTI) systems. This is effected by comparing the number of bits needed to encode the approximating RNN to the metric entropy of the class of LTI systems under consideration [2, 3]. The purpose of this note is to provide an elementary self-contained proof of the metric entropy results in [2, 3], in the process of which minor mathematical issues appearing in [2, 3] are cleaned up. These corrections also lead to the correction of a constant in a result in [1] (see Remark 2.5).Comment: [1] arXiv:2105.0255

Treatment and referral decisions under different physician payment mechanisms

International audienceThis paper analyzes and compares the incentive properties of some common payment mechanisms for GPs, namely fee for service (FFS), capitation and fundholding. It focuses on gatekeeping GPs and it specically recognizes GPs heterogeneity in both ability and altruism. It also allows inappropriate care by GPs to lead to more serious illnesses. The results are as follows. Capitation is the payment mechanism that induces the most referrals to expensive specialty care. Fundholding may induce almost as much referrals as capitation when the expected costs of GPs care are high relative to those of specialty care. Although driven by nancial incentives of different nature, the strategic behaviours associated with fundholding and FFS are very much alike. Finally, whether a regulator should use one or another payment mechanism for GPs will depend on (i) his priorities (either cost-containment or quality enhancement) which, in turn, depend on the expected cost difference between GPs care and specialty care, and (ii) the distribution of proles (diagnostic ability and altruism levels) among GPs