High-Multiplicity Fair Allocation Using Parametric Integer Linear Programming

Using insights from parametric integer linear programming, we significantly improve on our previous work [Proc. ACM EC 2019] on high-multiplicity fair allocation. Therein, answering an open question from previous work, we proved that the problem of finding envy-free Pareto-efficient allocations of indivisible items is fixed-parameter tractable with respect to the combined parameter "number of agents" plus "number of item types." Our central improvement, compared to this result, is to break the condition that the corresponding utility and multiplicity values have to be encoded in unary required there. Concretely, we show that, while preserving fixed-parameter tractability, these values can be encoded in binary, thus greatly expanding the range of feasible values.Comment: 15 pages; Published in the Proceedings of ECAI-202

On coalitional manipulation for multiwinner elections: shortlisting

Shortlisting of candidates—selecting a group of “best” candidates—is a special case of multiwinner elections. We provide the first in-depth study of the computational complexity of strategic voting for shortlisting based on the perhaps most basic voting rule in this scenario, -Bloc (every voter approves candidates). In particular, we investigate the influence of several different group evaluation functions (e.g., egalitarian versus utilitarian) and tie-breaking mechanisms modeling pessimistic and optimistic manipulators. Among other things, we conclude that in an egalitarian setting strategic voting may indeed be computationally intractable regardless of the tie-breaking rule. Altogether, we provide a fairly comprehensive picture of the computational complexity landscape of this scenario.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Humboldt-Universität zu Berlin (1034)Peer Reviewe

Multistage Committee Election

Electing a single committee of a small size is a classical and well-understood voting situation. Being interested in a sequence of committees, we introduce and study two time-dependent multistage models based on simple Plurality voting. Therein, we are given a sequence of voting profiles (stages) over the same set of agents and candidates, and our task is to find a small committee for each stage of high score. In the conservative model we additionally require that any two consecutive committees have a small symmetric difference. Analogously, in the revolutionary model we require large symmetric differences. We prove both models to be NP-hard even for a constant number of agents, and, based on this, initiate a parameterized complexity analysis for the most natural parameters and combinations thereof. Among other results, we prove both models to be in XP yet W[1]-hard regarding the number of stages, and that being revolutionary seems to be "easier" than being conservative: If the (upper- resp. lower-) bound on the size of symmetric differences is constant, the conservative model remains NP-hard while the revolutionary model becomes polynomial-time solvable

Laser-induced rotation of iodine molecules in He-nanodroplets: revivals and breaking-free

Rotation of molecules embedded in He nanodroplets is explored by a combination of fs laser-induced alignment experiments and angulon quasiparticle theory. We demonstrate that at low fluence of the fs alignment pulse, the molecule and its solvation shell can be set into coherent collective rotation lasting long enough to form revivals. With increasing fluence, however, the revivals disappear -- instead, rotational dynamics as rapid as for an isolated molecule is observed during the first few picoseconds. Classical calculations trace this phenomenon to transient decoupling of the molecule from its He shell. Our results open novel opportunities for studying non-equilibrium solute-solvent dynamics and quantum thermalization.Comment: 6+7 pages; 4+1 figures; 1 tabl

Bribery Can Get Harder in Structured Multiwinner Approval Election

We study the complexity of constructive bribery in the context of structured multiwinner approval elections. Given such an election, we ask whether a certain candidate can join the winning committee by adding, deleting, or swapping approvals, where each such action comes at a cost and we are limited by a budget. We assume our elections to either have the candidate interval or the voter interval property, and we require the property to hold also after the bribery. While structured elections usually make manipulative attacks significantly easier, our work also shows examples of the opposite behavior. We conclude by presenting preliminary insights regarding the destructive variant of our problem.Comment: 23 pages, 1 figure, 1 table, published in the Proceedings of AAMAS-2

Early brain perfusion improvement after ventriculoperitoneal shunt surgery in patients with idiopathic normal pressure hydrocephalus evaluated by 99mTc-HMPAO SPECT — preliminary report

BACKGROUND: Idiopathic normal pressure hydrocephalus (iNPH) is a clinical syndrome that consists of the triad: gait disturbance, mental deterioration and urinary incontinence associated with normal cerebrospinal fluid pressure (CSF), without pre-existing abnormalities. The most popular treatment option is surgical implantation of a shunt. Brain perfusion increase occurring months or years after successful shunt surgery is well described in the literature. Early improvement of perfusion is not well documented. Therefore, the objective of the present study was to determine patterns of brain perfusion changes 3–6 days after the ventriculoperitoneal shunting in patients with iNPH by using 99mTc-HMPAO SPECT. MATERIAL AND METHODS: Sixteen patients with iNPH (9 women, 7 men, mean age 64.1 ± 12.7 years) who underwent ventriculoperitoneal shunt surgery were included into the study group. Indications for implanting a shunt were based on clinical history, neuroimaging and CSF dynamic studies with an infusion test. Brain perfusion SPECT was performed 1–2 days before and 3–6 days after the surgical treatment. For comparison of perfusion before and after the surgery SPECT scans were assessed visually and semiquantitatively with voxel based analysis. RESULTS: No side effects were observed after the surgery. Brain perfusion improvement after shunting was observed in 10 patients (62.5%). Patterns of perfusion changes varied between patients, with combinations of different bilateral and lateralized brain regions involved. Perfusion increased in the whole brain (3 patients), in the right cerebral hemisphere (1 patient) or in the separate cerebral regions (6 patients): frontal, parietal, temporal, cerebellum, cingulate gyrus. Perfusion improvement was predominantly observed in the frontal lobes: right frontal (3 cases, 18.8%), left frontal (3 cases, 18.8%). CONCLUSIONS: Cerebral perfusion is recovered promptly after ventriculoperitoneal shunt surgery in about 60% of patients with iNPH. This improvement may be global or regional in different cerebral areas with prevalence of the frontal lobes

Perceptions of Digital Health Education Among European Medical Students: Mixed Methods Survey

Background: Digital health technologies hold promise to enhance patient-related outcomes, to support health care staff by reducing their workload, and to improve the coordination of care. As key users of digital health technologies, health care workers are crucial to enable a meaningful digital transformation of health care. Digital health literacy and digital skills should become prerequisite competencies for health professionals to facilitate the implementation and leverage the potential of digital technologies to improve health. Objective: We aimed to assess European medical students' perceived knowledge and opinions toward digital health, the status of digital health implementation in medical education, and the students' most pressing needs. Methods: The explanatory design of our mixed methods study was based on an online, anonymous, self-administered survey targeted toward European medical students. A linear regression analysis was used to identify the influence of the year of medical studies on the responses. Additional analysis was performed by grouping the responses by the self-evaluated frequency of eHealth technology use. Written responses to four qualitative questions in the survey were analyzed using an inductive approach. Results: The survey received a total of 451 responses from 39 European countries, and there were respondents for every year of medical studies. The majority of respondents saw advantages in the use of digital health. While 40.6% (183/451) felt prepared to work in a digitized health care system, more than half (240/451, 53.2%) evaluated their eHealth skills as poor or very poor. Medical students considered lack of education to be the reason for this, with 84.9% (383/451) agreeing or strongly agreeing that more digital health education should be implemented in the medical curriculum. Students demanded introductory and specific eHealth courses covering data management, ethical aspects, legal frameworks, research and entrepreneurial opportunities, role in public health and health systems, communication skills, and practical training. The emphasis lay on tailoring learning to future job requirements and interprofessional education. Conclusions: This study shows a lack of digital health-related formats in medical education and a perceived lack of digital health literacy among European medical students. Our findings indicate a gap between the willingness of medical students to take an active role by becoming key players in the digital transformation of health care and the education that they receive through their faculties