Elastic anisotropy and extreme Poisson’s ratios in single crystals

The relationship between elastic anisotropy and extreme Poisson’s ratio behaviour (either positive or negative) in single-crystalline materials has been investigated using experimentally determined single-crystal elastic constants for a wide range of solid materials. This makes use of a recently proposed elastic anisotropy index that is applicable to all crystal symmetries. For many real materials we find a striking correlation between the value of the elastic anisotropy index and the magnitudes of maximum and minimum Poisson’s ratios this is independent of crystal symmetry. This structure–property relationship provides new examples of auxetics and shows that negative Poisson’s ratios are actually not uncommon among many classes of inorganic (and organic) materials, including elemental metals, alloys, ionic solids, molecular solids and giant covalent networks.     

Transposition of an Exothermic Reaction From a Batch Reactor to an Intensified Continuous One

The implementation of chemical syntheses in a batch or semi-batch reactor is generally limited by the removal or the supply of heat. A way to enhance thermal performances is to develop multifunctional devices like heat exchanger/reactors. In this work, a novel heat exchanger/reactor is characterized in terms of residence time, pressure drops, and thermal behavior in order to estimate its capacities to perform an exothermic reaction: the oxidation of sodium thiosulfate by hydrogen peroxide. Experimental results highlight the performances of the heat exchanger/reactor in terms of intensification, which allows the implementation of the oxidation reaction at extreme operating conditions. These conditions are finally compared to the ones of a classical batch reactor.     

Sublimation rate and the mass-transfer coefficient for snow sublimation

Sublimation of snow is a fundamental process that affects the crystal structure of snow, and is important for ice core interpretation, remote sensing, snow hydrology and chemical processes in snow. Prior investigations have inferred the sublimation rate from energy, isotopic, or mass-balance calculations using field data. Consequently, these studies were unable to control many of the environmental parameters which determine sublimation rate (e.g. temperature, relative humidity, snow microstructure). We present sublimation rate measurements on snow samples in the laboratory, where we have controlled many of these parameters simultaneously. Results show that the air stream exiting the snow sample is typically saturated under a wide range of sample temperature and air-flow rate, within measurement precision. This result supports theoretical work on single ice grains which found that there is no energy barrier to be overcome during sublimation, and suggests that snow sublimation is limited by vapor diffusion into pore spaces, rather than sublimation at crystal faces. Undersaturation may be possible in large pore spaces (i.e. surface- or depth-hoar layers) with relatively high air-flow rates. We use these data to place bounds on the mass-transfer coefficient for snow as a linear function of Reynolds number, and find that h_m = 0.566 Re + 0.075.     

再见时光 安特卫普Hospital精品时装店

建筑师操刀室内设计,越来越多地个性设计发生在时尚门店的身上。这种建筑和时装的结合,是时尚品牌帝国提升自己形象的得意之举。无论是韩国庆熙宫的白色装置建筑,还是美国第五大道上舞动的楼梯设计,都让人赞叹。     

Impairments in the perception of odor-induced tastes and their relationship to impairments in taste perception.

Certain odors have tastelike qualities when sniffed. To the extent that these qualities are akin to real taste experiences, impairment in perception of odor-induced tastes should be accompanied by taste impairment, and vice versa. Twelve patients were selected with possible odor-induced taste impairments or general taste impairments via a screening test, along with a further 6 patients with a probable taste impairment (insular lesion). These 18 patients, along with 19 normal controls, completed a battery of odor, taste, visual control, and neuropsychological tests to assess impairments in odor-induced taste perception and general taste perception. Four patients had an odor-induced taste impairment and were also impaired on taste perception. A further analysis, using regression on the whole sample, indicated that taste impairments were associated with odor-induced taste abnormalities independent of other predictors. This pattern also held for the patient group alone. The insular patients also exhibited both taste and odor-induced taste impairments. This study is the first to demonstrate a relationship between impaired taste perception and the perception of odor-induced tastes and suggests that both may rely on certain common neural substrates. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A proposal of port scan detection method based on Packet-In Messages in OpenFlow networks and its evaluation

By quickly detecting a port scan and blocking the culprit host from the network, it is possible to minimize the spread of the damage by infected hosts and malicious users. In the past, various Software-Defined Networking (SDN)-based methods have been proposed, whose main advantage is the lower overhead compared to traditional methods that collect and analyze all captured traffic. On the other hand, due to the polling process used in these methods, it is necessary to set a short interval (e.g., few seconds) to keep the attacks' detection as short as possible. However, when the attack frequency is very low compared to normal traffic, there is an unnecessary overhead. In this paper, we propose a port scan detection method that considers the characteristics of Packet-In messages sent from the OpenFlow (OF) switch to the controller. This allows a prompt detection and with less overhead than conventional polling methods. The evaluation was conducted using both simulated and real traffic data. Results confirm that the proposed method can detect port scans with lower overhead than existing methods.     

Evidence for the use of an internal sense of direction in homing.

Path integration, the ability to maintain a representation of location and direction on the basis of internal cues, is thought to be important for navigation and the learning of spatial relationships. Representations of location and direction in the brain, such as head direction cells, grid cells, and place cells in the limbic system, are thought to underlie navigation by path integration. While this idea is generally consistent with lesion studies, the relationship between such neural activity and behavior has not been studied on a task where animals demonstrably use a path integration strategy. Here we report the development of such a task in rats: by slowly rotating rats before their return to a trial-unique home base, we could show subjects relied on internal cues only to navigate. To illustrate how this task can be combined with recording, we show examples of simultaneously recorded head direction cells in which neural activity is closely related to rats’ homing direction. These results support the notion that rats can navigate by path integration, that this ability depends on head direction cells, and suggest a convenient behavioral paradigm for investigating the neural basis of navigation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Constrained visual servoing under uncertain dynamics

In visual servoing, limitations in the field of view of the vision sensors are either ignored or treated at the kinematic level. The former can easily jeopardise task success, while the latter reduces the maximum achievable robotic motion speeds. In this work, the aforementioned literature gap is filled by designing and rigorously analysing a torque controller that guarantees prescribed transient and steady-state performance attributes on the image feature coordinate errors, while respecting the field-of-view constraints. No path planning and no information regarding the actual system dynamics are required. In addition, no approximation structures (i.e. neural networks, fuzzy systems, etc.) are utilised to acquire such knowledge. The proposed visual servo controller is static, involving very few and simple calculations to produce the control signal, making its implementation on embedded control platforms straightforward. Simulation studies are utilised to illustrate the motivation and to clarify–verify the theoretical findings.     

Patterns of Phytochemical Variation in Mimulus guttatus (Yellow Monkeyflower)

The search for general patterns in the production and allocation of plant defense traits will be facilitated by characterizing multivariate suites of defense, as well as by studying additional plant taxa, particularly those with available genomic resources. Here, we investigated patterns of genetic variation in phytochemical defenses (phenylpropanoid glycosides, PPGs) in Mimulus guttatus (yellow monkeyflower). We grew plants derived from several natural populations, consisting of multiple full-sibling families within each population, in a common greenhouse environment. We found substantial variation in the constitutive multivariate PPG phenotype and in constitutive levels of individual phytochemicals within plants (among leaves of different ages), within populations (among full-sibling families), and among populations. Populations consisting of annual plants generally, but not always, had lower concentrations of phytochemicals than did populations of perennial plants. Populations differed in their plastic response to artificial herbivory, both in the overall multivariate PPG phenotype and in the individual phytochemicals. The relationship between phytochemistry and another defense trait, trichomes, differed among populations. Finally, we demonstrated that one of the PPGs, verbascoside, acts as a feeding stimulant rather than a feeding deterrent for a specialist herbivore of M. guttatus, the buckeye caterpillar (Junonia coenia Nymphalidae). Given its available genetic resources, numerous, easily accessible natural populations, and patterns of genetic variation highlighted in this research, M. guttatus provides an ideal model system in which to test ecological and evolutionary theories of plant-herbivore interactions.