A Level-2 Reformulation–Linearization Technique Bound for the Quadratic Assignment Problem

This paper studies polyhedral methods for the quadratic assignment problem. Bounds on the objective value are obtained using mixed 0–1 linear representations that result from a reformulation–linearization technique (rlt). The rlt provides different “levels” of representations that give increasing strength. Prior studies have shown that even the weakest level-1 form yields very tight bounds, which in turn lead to improved solution methodologies. This paper focuses on implementing level-2. We compare level-2 with level-1 and other bounding mechanisms, in terms of both overall strength and ease of computation. In so doing, we extend earlier work on level-1 by implementing a Lagrangian relaxation that exploits block-diagonal structure present in the constraints. The bounds are embedded within an enumerative algorithm to devise an exact solution strategy. Our computer results are notable, exhibiting a dramatic reduction in nodes examined in the enumerative phase, and allowing for the exact solution of large instances

The effect of agmatine on trichothecene type B and zearalenone production in Fusarium graminearum, F. culmorum and F. poae

Agmatine and other putrescines are known for being strong inducers of deoxynivalenol (DON) production in Fusarium graminearum. Other important species produce DON and/or other trichothecene type B toxins (3 acetylated DON, 15 acetylated DON, Fusarenon-X, Nivalenol), such as F. culmorum and F. poae. In order to verify whether the mechanism of the regulation of trichothecene type B induction by agmatine is shared by different species of Fusarium, we tested the hypothesis on 19 strains belonging to 3 Fusarium species (F. graminearum, F. culmorum, F. poae) with diverse genetic chemotypes (3ADON, 15ADON, NIV) by measuring trichothecene B toxins such as DON, NIV, Fusarenon-X, 3ADON and 15ADON. Moreover, we tested whether other toxins like zearalenone were also boosted by agmatine. The trichothecene type B boosting effect was observed in the majority of strains (13 out of 19) in all the three species. Representative strains from all three genetic chemotypes were able to boost toxin production after agmatine treatment. Weidentified the non-responding strains to the agmatine stimulus, which may contribute to deciphering the regulatory mechanisms that link toxin production to agmatine (and, more generally, polyamines)

Development of a miniature articulated arm and pair of eyes for the humanoid robot Robota

Humanoids remain luxurious robots, not easily purchasable or reproducible. The Robota project aims at building a low cost open humanoid platform, for use as educational tool for normal and disabled children. This paper reports on the mechanical design of a miniature 7 degrees of freedom articulated arm and of a miniature 3 degrees of freedom pair of eyes for Robota. We describe in details the mechanical construction, the electronic circuits and the control system, so that these could be easily duplicated by other laboratories

Land use alters trophic redundancy and resource flow through stream food webs.

The changes to physical and chemical ecosystem characteristics as a response to pervasive and intensifying land use have the potential to alter the consumer-resource interactions and to rewire the flow of energy through entire food webs. We investigated these structural and functional properties of food webs in stream ecosystems distributed across woodland, agricultural and urban areas in the Zagreb region of Croatia. We compared resource availability and consumer diet composition using stable isotope mixing models and tested how the isotopic variance of basal resources, primary consumers, macroinvertebrate predators and other food web characteristics change with different land-use types. Combination of increased loading and altered composition of nutrients, lower water discharge and higher light availability at urban sites likely promoted the contribution of aquatic macrophytes to diets of primary consumers. Macroinvertebrate predators shifted their diet, relying more on active filterers at urban sites relative to woodland and agricultural sites. Urban food webs also had lower trophic redundancy (i.e. fewer species at each trophic level) and a more homogenized energy flow from lower to higher trophic levels. There was no effect of land use on isotopic variation of basal resources, primary consumers or macroinvertebrate predators, but all these trophic groups at urban and agricultural sites were 15 N-enriched relative to their counterparts in woodland stream food webs. The physical and chemical ecosystem characteristics associated with intensive land use altered the resource availability, trophic redundancy and the flow of energy to other trophic levels, with potentially negative consequences for community dynamics and ecosystem functioning. These empirical findings indicate that reducing nutrient pollution, agricultural runoffs and maintaining riparian vegetation can mitigate the impacts of land use on structure and function of stream ecosystems

Studies of New Vector Resonances at the CLIC Multi-TeV e+e- Collider

Several models predict the existence of new vector resonances in the multi-TeV region, which can be produced in high energy e+e- collisions in the s-channel. In this paper we review the existing limits on the masses of these resonances from LEP/SLC and TEVATRON data and from atomic parity violation in some specific models. We study the potential of a multi-TeV e+e- collider, such as CLIC, for the determination of their properties and nature.Comment: 17 pages, 16 EPS figures, uses JHEP3.cl

CTF3: Design of Driving Beam Combiner Ring

In CTF3 the beam compression of the driving beam structure between the main linac and the decelerating section is obtained with a delay loop and a combiner ring which increase the pulse current by a factor 10. The design of the combiner ring is presented. Tunable isochronicity condition, corrected up to second order, should assure preservation of the correlation in the longitudinal phase space during the compression. Path-length tuning devices are included in the combiner ring layout to compensate for orbit variations

Coordination Dynamics of Upper Limbs in Swimming: Effects of Speed and Fluid Flow Manipulation

Purpose: Motor outputs are governed by dynamics organized around stable states and spontaneous transitions: we seek to investigate the swimmers’ motor behavior flexibility as a function of speed and aquatic environment manipulations. Method: Eight elite male swimmers partook an eight-level incremental test (4% increment from 76% to 104% of their mean speed on 200 m front crawl) in a quasi-static aquatic environment (pool). Swimmers then partook another incremental test at similar effort in a dynamic aquatic environment (swimming flume) up to maximal speed. Stroke rate (SR), index of coordination (IdC) and intersegmental coupling of the upper limbs were computed from the inertial sensors located on the upper limbs and the sacrum. Results: With speed increase, SR values presented a steeper linear increase in the pool than in the flume. IdC values increased also in the pool but remained stable in the flume. Individual SR and IdC vs. speed increase displayed second-order polynomial dynamics, indicative of adaptive flexibility with a range of extremum values more restricted in the flume. Finally, a reduction of the in-phase coordination pattern was noted with flume speed increase. Conclusions: Action possibilities were strongly constrained in the flume at the highest speeds as the fluid flow led to discontinuity in the propulsive actions of the upper limbs and lack of in-phase inter-segmental coordination. This highlights that the behavioral flexibility was restricted in the flume in comparison to the pool, in which the exploitation of opportunities for action involved a larger number of degrees of freedom in the movement