Heterotic T-folds with a small number of neutral moduli

We discuss non-geometric supersymmetric heterotic string models in D=4, in the framework of the free fermionic construction. We perform a systematic scan of models with four a priori left-right asymmetric Z2 projections and shifts. We analyze some 220 models, identifying 18 inequivalent classes and addressing variants generated by discrete torsions. They do not contain geometrical or trivial neutral moduli, apart from the dilaton. However, we show the existence of flat directions in the form of exactly marginal deformations and identify patterns of symmetry breaking where product gauge groups, realized at level one, are broken to their diagonal at higher level. We also describe an “inverse Gepner map” from Heterotic to Type II models that could be used, in certain non geometric settings, to define “effective” topological invariants.

Numerical model of the human cornea based on stromal microstructure: identification of mechanical properties for two age groups

The optical quality of the human eye mainly depends on the refractive performance of the cornea. The shape of the cornea is a mechanical balance between intraocular pressure and tissue intrinsic stiffness. Several surgical procedures in ophthalmology alter the biomechanics of the cornea to provoke local or global curvature changes for vision correction. Legitimated by the large number of surgical interventions performed every day, the demand for a deeper understanding of corneal biomechanics is rising to improve the safety of procedures and medical devices. The aim of our work is to propose a numerical model of corneal biomechanics, based on the stromal microstructure. Our novel anisotropic constitutive material law features a probabilistic weighting approach to model collagen fiber distribution as observed on human cornea by Xray scattering analysis (Aghamohammadzadeh et. al., Structure, February 2004). Furthermore, collagen cross-linking was explicitly included in the strain energy function. Results showed that the proposed model is able to successfully reproduce both inflation and extensiometry experimental data (Elsheikh et. al., Curr Eye Res, 2007; Elsheikh et. al., Exp Eye Res, May 2008). In addition, the mechanical properties calculated for patients of different age groups (Group A: 65-79 years; Group B: 80-95 years) demonstrate an increased collagen cross-linking, and a decrease in collagen fiber elasticity from younger to older specimen. These findings correspond to what is known about maturing fibrous biological tissue. Since the presented model can handle different loading situations and includes the anisotropic distribution of collagen fibers, it has the potential to simulate clinical procedures involving nonsymmetrical tissue interventions. In the future, such mechanical model can be used to improve surgical planning and the design of next generation ophthalmic devices.

Design-based stereology: Planning, volumetry and sampling are crucial steps for a successful study

Quantitative data obtained by means of design-based stereology can add valuable information to studies performed on a diversity of organs, in particular when correlated to functional/physiological and biochemical data. Design-based stereology is based on a sound statistical background and can be used to generate accurate data which are in line with principles of good laboratory practice. In addition, by adjusting the study design an appropriate precision can be achieved to find relevant differences between groups. For the success of the stereological assessment detailed planning is necessary. In this review we focus on common pitfalls encountered during stereological assessment. An exemplary workflow is included, and based on authentic examples, we illustrate a number of sampling principles which can be implemented to obtain properly sampled tissue blocks for various purposes.

Comparing different boosters of planning interventions on changes in fat consumption in overweight and obese individuals: A randomized controlled trial

Single planning interventions have been found to promote short-term dietary change. Repeated planning interventions may foster long-term effects on behavior change. It remains unknown whether there is a critical number of boosters to establish long-term maintenance of behavioral changes. This study aimed at investigating what social-cognitive variables mediate the effects of the interventions on dietary behavior change. Overall, 373 participants (n = 270 women, 72.4%; age M = 52.42, SD = 12.79) were randomly allocated to one of five groups: a control group, a single planning group, and three groups with 3, 6, or 9 weeks' repeated planning interventions. Follow-ups took place 4, 6, and 12 months after baseline. Change in fat consumption was not promoted by any of the interventions. In terms of social-cognitive variables, intentions, self-efficacy and coping planning displayed a time × group interaction, with the 9 weeks' planning group showing the most beneficial effects. Effect sizes, however, were very small. None of the tested planning interventions successfully promoted change in fat consumption across the 12 month period. This, however, could not be explained by problems with adherence to the intervention protocol. Potential explanations for this unexpected result are discussed.

Heuristic decomposition and LP-based scheduling in make-and-pack production

In this paper, we are concerned about the short-term scheduling of industrial make-and-pack production processes. The planning problem consists in minimizing the production makespan while meeting given end-product demands. Sequence-dependent changeover times, multi-purpose storage units with finite capacities, quarantine times, batch splitting, partial equipment connectivity, material transfer times, and a large number of operations contribute to the complexity of the problem. Known MILP formulations cover all technological constraints of such production processes, but only small problem instances can be solved in reasonable CPU times. In this paper, we develop a heuristic in order to tackle large instances. Under this heuristic, groups of batches are scheduled iteratively using a novel MILP formulation; the assignment of the batches to the groups and the scheduling sequence of the groups are determined using a priority rule. We demonstrate the applicability by means of a real-world production process.

Fostering networking behavior, career planning and optimism, and subjective career success: An intervention study

The present study evaluated personal resource-oriented interventions supporting the career development of young academics, working at German universities within the STEM fields. The study sought to foster subjective career success by improving networking behavior, career planning, and career optimism. The study involved a quasi-experimental pre-post intervention with two intervention and two control groups (N = 81 research associates). Participants of the first intervention group received networking training; participants of the second intervention group received the same networking training plus individual career coaching. Participants of both intervention groups were female. Participants of the control groups (i.e., male vs. female group) did not participate in any intervention. As expected, path analyses, based on mean differences frompre-test to post-test, revealed an increase in career planning and career optimism within the networking plus career coaching intervention group, that was indirectly positively related to changes in subjective career success. Contrary to our expectations, the networking group training alone and in combination with the career coaching showed no effectiveness in fostering networking behavior. Results are discussed in the context of career counseling and intervention effectiveness studies.