The Stackelberg Minimum Spanning Tree Game

We consider a one-round two-player network pricing game, the Stackelberg Minimum Spanning Tree game or StackMST. The game is played on a graph (representing a network), whose edges are colored either red or blue, and where the red edges have a given fixed cost (representing the competitor??s prices). The first player chooses an assignment of prices to the blue edges, and the second player then buys the cheapest possible minimum spanning tree, using any combination of red and blue edges. The goal of the first player is to maximize the total price of purchased blue edges. This game is the minimum spanning tree analog of the well-studied Stackelberg shortest-path game. We analyze the complexity and approximability of the first player??s best strategy in StackMST. In particular, we prove that the problem is APX-hard even if there are only two different red costs, and give an approximation algorithm whose approximation ratio is at most min?{k,1+ln?b,1+ln?W}, where k is the number of distinct red costs, b is the number of blue edges, and W is the maximum ratio between red costs. We also give a natural integer linear programming formulation of the problem, and show that the integrality gap of the fractional relaxation asymptotically matches the approximation guarantee of our algorithm.     

Growth and Luminescence of Polytypic InP on Epitaxial Graphene

Van der Waals epitaxy is an attractive alternative to direct heteroepitaxy where the forced coherency at the interface cannot sustain large differences in lattice parameters and thermal expansion coefficients between the substrate and the epilayer. Herein, the growth of monocrystalline InP on Ge and SiO₂/Si substrates using graphene as an interfacial layer is demonstrated. Micrometer‐sized InP crystals are found to grow with interfaces of high crystalline quality and with different degrees of coalescence depending on the growth conditions. Some InP crystals exhibit a polytypic structure, consisting of alternating zinc‐blende and wurtzite phases, forming a type‐II homojunction with well (barrier) width of about 10 nm. The optical properties, investigated using room temperature nano‐cathodoluminescence, indicate the signatures of the direct optical transitions at 1.34 eV across the gap of the zinc‐blende phase and the indirect transitions at ≈ 1.31 eV originating from the alternating zinc‐blende and wurtzite phases. Additionally, the InP nanorods, found growing mainly on the graphene/SiO₂/Si substrate, show optical transition across the gap of the wurtzite phase at ≈ 1.42 eV. This demonstration of InP growth on graphene and the correlative study between the structure and optical properties pave the way to develop hybrid structures for potential applications in integrated photonic and optoelectronic devices.     

Quality differences of gilthead sea bream from distinct production systems in Southern Europe: Intensive,integrated, semi-intensive or extensive systems

The quality of gilthead sea bream from distinct production systems and geographical locations in Southern Europe was evaluated to differentiate aquaculture products from extensive, integrated and semi-intensive systems from the ones produced intensively. This work analysed the external appearance of fish, yields after filleting as well as nutritional, sensory and histological characteristics of the muscle. The results showed that the yellow-golden line between eyes and the shiny red spot on the gill cover can be important and easy criteria to discriminate aquaculture products. Trimming losses are higher in fish from intensive systems. Lipid content of fish from extensive systems was significantly lower than values observed for fish reared intensively. Samples from the integrated and extensive systems showed the best n-3/n-6 ratio, contrarily to intensive systems, but it is difficult to establish clear quality markers to differentiate gilthead sea bream according to the rearing system. Regarding sensory characteristics, the sea bream flesh from intensive systems seems firmer and denser, having smaller white fibres and higher density of fibres in the dorsal muscle. The taste and odour of fatty fish was less strong in fish reared in non-intensive conditions, but extensive rearing in earthen pond is more propitious to the development of certain characteristics related to the environment.     

Fat Content and Fillet Shape of Atlantic Salmon: Relevance for Processing Yield and Quality of Raw and Smoked Products

ABSTRACT: Relevance of fat content and fillet shape of Atlantic salmon for quality and yield during smoking processing was investigated. Fat content significantly influenced quality of raw and smoked products, although the interactions varied according to the raw material used and smoking temperature. In raw and smoked fillets, increasing fat content coincided with increasing L* and b*-values and decreasing fat holding capacity. In smoked salmon, fat content also correlated positively to the a*-value, smoke-intensity-/wood-fire flavor and fatty texture, and negatively to water holding capacity and shear-force. Weight loss during salting and smoking decreased with increasing fat content, and voluminous shaped fillets gave higher yield than slim fillets. Keywords: Atlantic salmon, fat content, fillet shape, salmon quality, processing     

老厂房内的现代生活Redpath厂房第Ⅱ、Ⅲ期项目改建

位于Lachine运河畔的Redpath制糖厂曾是蒙特利尔标志性的工业建筑之一,其历史文化价值受到加拿大公园协会和蒙特利尔市政府的肯定和保护。The Groupe Cardinal Hardy公司出色地完成了对这座具有历史意义的工业遗产     

Performance characteristics of high-brightness, CW, diode laser arrays

Recently developed, high-brightness diode laser arrays have been tested at 50°C at output powers of 0.5 W CW and 1.0W CW from 100?m- and 200?m-wide active regions, respectively. The extrapolated lifetimes at room temperature exceed 40000 h. The maximum CW power output prior to catastrophic degradation of the facets is 2.0 W for the 100?m device and greater than 3 W for the 200?m-aperture device.     

An Integrated System for Intraoperative Cardiac Activation Mapping

This paper describes an electrophysiological data acquisition and processing system which is programmed to rapidly generate cardiac activation maps for experimental studies and antiarrhythmia surgery. The basic system consists of a PDP-11/23+ minicomputer (DEC) with 1.5 Mbit memory and a 10 Mbit hard disk, a 64-channel data acquisition unit controlled by a specially designed interface card, and a modified video terminal. The data acquisition unit includes 64 instrumentation amplifiers with programmable gain and bandwidth. Signals are sampled and digitized at a maximum rate of 1000 samples/s/channel (10 bits) and transferred to the interface card by an optically isolated data bus. The operator controls the system by pointing to function boxes and signals appearing on the graphic terminal with a light pen. The software is based on a general-purpose data acquisition program with a command language interpreter. This program includes a setup section to define the system's parameters (gains, bandwidths, sampling rate) and an acquisition section to initiate data recording into a ring buffer, display the signals simultaneously on the screen, select heartbeats, and store or retrieve data on disk. The data processing procedures (in this case, mapping) can be easily interchanged to accommodate future signal processing needs. Current mapping procedures include an automatic detection section and an editor to manually define the local activation times on any electrogram. Another section displays the activation sequence as a map of isochronal lines. Typical processing time from the selection of a heartbeat to the visualization of the corresponding isochrone map is 2 min.