On the Incompatibility of Standard Quantum Mechanics and the de Broglie-Bohm Theory

It is shown that the de Broglie-Bohm quantum theory of multi-particle systems is incompatible with the standard quantum theory of such systems unless the former is ergodic. A realistic experiment is suggested to distinguish between the two theories.Comment: A few technical changes incorporated in section V without any change in conclusion

Picture This: Using photo-research exhibits as science outreach

Is a picture worth a thousand words? This paper discusses a unique science outreach initiative–provocative photo-research exhibits on sexism in science. Gender imbalance in science, technology, engineering, and math (STEM) is not only a concern from a social justice perspective, but also has negative consequences for scientific innovation and the economy, given that lack of workplace gender diversity is associated with lower revenue and returns. Science outreach (i.e., public outreach by scientists) could be particularly impactful in Waterloo, Ontario – a region known as ‘Canada’s Silicon Valley’ that contributes over $30-billion annually to the global economy. Portraying complex social issues using a visual medium has the potential to be accessible to a diverse audience. Images from two photo-research exhibits #DistractinglySexist (2015) and #DistractinglyHonest (2016) were based on social-psychological literature and findings from research by two of the authors (Hennessey and Foster) on the social costs of confronting sexism in science. Feedback indicates that these exhibits are effective outreach tools, and appear to facilitate discussions on sexism in science, and expand the social network of women in science by connecting those in the series and people who engage with exhibit materials

Internet Exchanges for Used Books: An Empirical Analysis of Welfare Implications

Information technology-enabled exchanges have enhanced the viability of a variety of secondary markets, notably markets for used books. Electronic used book exchanges, in particular, offer a wider selection, lower search costs, and significantly lower prices than physical used bookstores do. The increased viability of these used book markets has caused concern among groups such as the Book Publishers Association and AuthorâÃÂÃÂs Guild who believe that used book markets will significantly cannibalize new book sales. This proposition, while theoretically possible, is based on speculation as opposed to empirical evidence. In this research, we use a unique dataset collected from Amazon.comâÃÂÃÂs new and used marketplaces to estimate the impact of IT-enabled used book markets on new book sales. We use these data to calculate the impact of these secondary market exchanges on consumer and publisher welfare by calculating the cross-price elasticity of new books sales with respect to used book prices. Our analysis suggests that IT-enabled secondary market exchanges increase consumer surplus by approximately $70 million annually. Further, we find that only 15cannibalize new book purchases. The remaining 85lose only$32 million in gross profit annually (about 0.2% of total gross profit) due to the presence of AmazonâÃÂÃÂs used book markets. Further, the additional used book readership gain from these electronic markets may mitigate author losses through increased revenue from secondary sources such as speaking and licensing fees. These surplus changes, combined with the estimated $64 million the used book market added to AmazonâÃÂÃÂs gross profits, show that IT-enabled used markets for books have a strong positive first-order impact on total welfare.Information Systems Working Papers Serie

Two-particle interference in standard and Bohmian quantum mechanics

The compatibility of standard and Bohmian quantum mechanics has recently been challenged in the context of two-particle interference, both from a theoretical and an experimental point of view. We analyze different setups proposed and derive corresponding exact forms for Bohmian equations of motion. The equations are then solved numerically, and shown to reproduce standard quantum-mechanical results.Comment: Minor corrections, 2 references added, version to appear in J. Phys.

The Association Between Discrimination and Sleep is Exacerbated in Individuals with Comorbid Chronic Health Conditions

Introduction: The consequences of recurrent, stressful daily experiences for sleep health appear intensified in individuals with pre-existing health conditions. Although discrimination has been associated with sleep outcomes, the role of comorbid chronic health conditions (CCHCs), and impact of perceived discrimination, remains unclear. The present study investigated (1) the associations between daily discrimination and sleep and (2) moderating roles of CCHCs and daily life interference and hardship. Methods: The current study utilized archival data from the Midlife in the United States (MIDUS) Study II. Participants, 174 adults (51% female, Mage=57 yrs., SD=11.5 yrs.), completed 7 days of actigraphy, sleep diary, PSQI, and CCHC-reporting measures. Models examined the moderating effects of CCHCs, daily interference, and hardship on the association between discrimination and sleep. Results: Daily discriminatory experiences predicted numerous poor sleep outcomes, exacerbated for persons with higher CCHCs. Higher comorbidity (95% CI=5.40, 68.75) exacerbated the association between discrimination and TSTactigraphy, further strengthened by perceived hardship (95% CI=-3.75, -.40) and interference (95% CI=-3.65, -.30). Number of CCHCs, qualified by perceived hardship (95% CI=.00, .04) and interference (95% CI=.01, .05), predicted diary sleep quality above discrimination. The interaction between CCHCs and hardship predicted global PSQI scores (95% CI=-.91, -.12) beyond discrimination. Conclusion: Daily experiences of discrimination are associated with decreased sleep duration and quality. These associations were stronger for individuals with multiple CCHCs. Exacerbating CCHC effects were perpetuated by perceived interference and hardships, suggesting individual emotion regulation (ER) differences. Future research should attend to sleep-related consequences of differential discrimination-informed ER by persons with CCHCs.https://scholarscompass.vcu.edu/gradposters/1042/thumbnail.jp

Endogenous Quasicycles and Stochastic Coherence in a Closed Endemic Model

We study the role of demographic fluctuations in typical endemics as exemplified by the stochastic SIRS model. The birth-death master equation of the model is simulated using exact numerics and analysed within the linear noise approximation. The endemic fixed point is unstable to internal demographic noise, and leads to sustained oscillations. This is ensured when the eigenvalues ($\lambda$) of the linearised drift matrix are complex, which in turn, is possible only if detailed balance is violated. In the oscillatory state, the phases decorrelate asymptotically, distinguishing such oscillations from those produced by external periodic forcing. These so-called quasicycles are of sufficient strength to be detected reliably only when the ratio $|Im(\lambda)/Re(\lambda)|$ is of order unity. The coherence or regularity of these oscillations show a maximum as a function of population size, an effect known variously as stochastic coherence or coherence resonance. We find that stochastic coherence can be simply understood as resulting from a non-monotonic variation of $|Im(\lambda)/Re(\lambda)|$ with population size. Thus, within the linear noise approximation, stochastic coherence can be predicted from a purely deterministic analysis. The non-normality of the linearised drift matrix, associated with the violation of detailed balance, leads to enhanced fluctuations in the population amplitudes.Comment: 21 pages, 8 figure

Sustainability performance measurement : a preliminary classification framework of models and indicators

In this position paper we focus on the diversity of sustainability measurements. Based on existing research on performance measurement, we propose a preliminary classification framework summarizing sustainability models and indicators. By describing illustrative examples, we claim that several models and indicators can be distinguished with their own peculiarities. Having such a framework is interesting for both academia and business to structure the range of models and indicators and to ultimately select the appropriate sustainability measurement approach. The proposed framework should be validated by further research

An ex vivo model using human osteoarthritic cartilage demonstrates the release of bioactive insulin-like growth factor-1 from a collagen-glycosaminoglycan scaffold.

Biomimetic scaffolds hold great promise for therapeutic repair of cartilage, but although most scaffolds are tested with cells in vitro, there are very few ex vivo models (EVMs) where adult cartilage and scaffolds are co-cultured to optimize their interaction prior to in vivo studies. This study describes a simple, non-compressive method that is applicable to mammalian or human cartilage and provides a reasonable throughput of samples. Rings of full-depth articular cartilage slices were derived from human donors undergoing knee replacement for osteoarthritis and a 3 mm core of a collagen/glycosaminoglycan biomimetic scaffold (Tigenix, UK) inserted to create the EVM. Adult osteoarthritis chondrocytes were seeded into the scaffold and cultures maintained for up to 30 days. Ex vivo models were stable throughout experiments, and cells remained viable. Chondrocytes seeded into the EVM attached throughout the scaffold and in contact with the cartilage explants. Cell migration and deposition of extracellular matrix proteins in the scaffold was enhanced by growth factors particularly if the scaffold was preloaded with growth factors. This study demonstrates that the EVM represents a suitable model that has potential for testing a range of therapeutic parameters such as numbers/types of cell, growth factors or therapeutic drugs before progressing to costly pre-clinical trials.The authors would like to kindly acknowledge funding from the EPSRC and Tigenix Ltd (LM), Technology Strategy Board and Tigenix Ltd (JW) and the NIHR (DH).This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/cbf.3112