Improved mixed-integer programming models for the multiprocessor scheduling problem with communication delays

We revise existing and introduce new mixed-integer programming models for the Multiprocessor scheduling problem with communication delays. The basis for both is the identification of two major modeling strategies one of which can be considered ordering-based, and the other assignment-based. We first reveal redundancies in the encoding of feasible solutions found in present formulations and discuss how they can be avoided. For the assignment-based approach, we propose new inequalities that lead to provably stronger continuous relaxations and better performance in practice. Moreover, we derive a third, novel modeling strategy and show how to more compactly linearize assignment formulations with quadratic constraints. In a comprehensive experimental comparison of representative models that reflect the state-of-the-art in terms of strength and size, we evaluate not only running times but also the obtained lower and upper bounds on the makespan for the harder instances of a large scale benchmark set.     

Form Perception of Partly Occluded Shapes in 4‐Month‐Old Infants

Two habituation experiments were conducted to investigate how 4‐month‐old infants perceive partly occluded shapes. In the first experiment, we presented a simple, partly occluded shape to the infants until habituation was reached. Then we showed either a probable completion (one that would be predicted on the basis of both local and global cues) or an improbable completion. Longer looking times were found for the improbably completed shape (compared to probable and control conditions), suggesting that the probable shape was perceived during partial occlusion. In the second experiment, infants were habituated to more ambiguous partly occluded shapes, where local and global cues would result in different completions. For adults, the percept of these shapes is usually dominated by global influences. However, after habituation the infants looked longer at the globally completed shapes. These results suggest that by the age of 4 months, infants are able to infer the perceptual completion of partly occluded shapes, but for more ambiguous shapes, this completion seems to be dominated by local influences.     

Single-peaked Compatible Preference Profiles: Some Combinatorial Results

This paper examines combinatorial problems in connection with single-peaked preference orderings on a unidimensional scale. A binary relation, dominance, is defined on the set of connected orderings. Relevant properties of the corresponding poset and cover graph are discussed. A formula for the number of pairs of connected orderings consistent with spatial single-peakedness is derived. The total number of such pairs is shown to be expressible in a simple form involving binomial probabilities. A possible application is a coalition formation process of the kind examined by Brams et al. (J Theor Polit 14:359–383, 2002), where actors have single-peaked preferences on a common scale.     

The reliance on recognition and majority vote heuristics over privacy concerns when selecting smartphone apps among German and US consumers

The smartphone app market is a prime example of a digital market where consumers are tasked with selecting one option among a plethora of alternatives, at times indistinguishable from one another. Building upon findings on information processing and decision-making, we postulate that consumers follow simple (rather than complex) heuristic rules to navigate the app market. In particular, we focus on two such strategies: the recognition heuristic and the majority vote heuristic. App privacy information was also considered as a potentially salient cue in the decision-making process, given the personal data stored on smartphones. Results of a mixed-method design (behavioral analysis and think-aloud protocols) study with German (N?=?18) and US (N?=?25) students find a dominance of the recognition heuristic. Decisions are further supported by majority vote heuristics. Privacy information is largely disregarded, particularly by US participants. Implications for app market design and engagement are discussed.     

Both Whistleblowers and the Scientists They Accuse Are Vulnerable and Deserve Protection

Whistleblowers play an important role diagnosing research misconduct, but often experience severe negative consequences. That is also true for incorrectly accused scientists. Both categories are vulnerable and deserve protection. Whistleblowers must proceed carefully and cautiously. Anonymous whistleblowing should be discouraged but cannot be ignored when the allegations are specific, serious, and plausible. When accused of a breach of research integrity it is important to be as transparent as possible. Sometimes accusations are false in the sense that the accuser knows or should know that the allegations are untrue. A mala fide whistleblower typically does not act carefully and we postulate a typology that may help in detecting them. Striking the right balance between whistleblower protection and timely unmasking false and identifying incorrect accusations is a tough dilemma leaders of research institutions have to face.     

How Does the Age Gap Between Partners Affect Their Survival?

I use hazard regression methods to examine how the age difference between spouses affects their survival. In many countries, the age difference between spouses at marriage has remained relatively stable for several decades. In Denmark, men are, on average, about three years older than the women they marry. Previous studies of the age gap between spouses with respect to mortality found that having a younger spouse is beneficial, while having an older spouse is detrimental for one’s own survival. Most of the observed effects could not be explained satisfactorily until now, mainly because of methodological drawbacks and insufficiency of the data. The most common explanations refer to selection effects, caregiving in later life, and some positive psychological and sociological effects of having a younger spouse. The present study extends earlier work by using longitudinal Danish register data that include the entire history of key demographic events of the whole population from 1990 onward. Controlling for confounding factors such as education and wealth, results suggest that having a younger spouse is beneficial for men but detrimental for women, while having an older spouse is detrimental for both sexes.