Maternal control of embryogenesis by MEDEA, a polycomb group gene in Arabidopsis

The gametophytic maternal effect mutant medea (mea) shows aberrant growth regulation during embryogenesis in Arabidopsis thaliana. Embryos derived from mea eggs grow excessively and die during seed desiccation. Embryo lethality is independent of the paternal contribution and gene dosage. The mea phenotype is consistent with the parental conflict theory for the evolution of parent-of-origin-specific effects. MEA encodes a SET domain protein similar to Enhancer of zeste, a member of the Polycomb group. In animals, Polycomb group proteins ensure the stable inheritance of expression patterns through cell division and regulate the control of cell proliferation.     

LOCAL THERMAL CHARACTERIZATION OF INNER GUN BARREL REFRACTORY METALLIC COATINGS

Large-caliber gun barrels are coated, on their internal surface, by hard and refractory metallic layers. The thermophysical properties of such coatings are generally very different of bulk materials ones, and liable to evolve following the thermal cyclings. Nevertheless, the knowledge of these properties is necessary for modeling the gun barrels behavior. In the present work, a photothermal microanalysis method has been used to measure the local thermal diffusivity within such a coating. The periodic excitation is localized on a micrometer-scale spot and the temperature evolution in the thermally excited zone is monitored by photoreflection on a spot with similar size. Local thermal properties are identified from thermal transfer function analysis, i.e., phase-lag evolution versus frequency. Results obtained on an aged chromium coating, on which several local diffusivity measurements have been undertaken along the depth, are presented. The diffusivity is higher near the surface than toward the interior of the coating, which has undergone less important heating during the gun lifetime. This behavior is compared to the microhardness evolution along the coating depth.     

How to reach 100% selectivity in H2O2-based oxidation of 2,3,6-trimethylphenol to trimethyl-p-benzoquinone over Ti,Si-catalysts

A comprehensive study of structure/activity/selectivity relationships and mechanistic aspects of the oxidation of 2,3,6-trimethylphenol (TMP) with aqueous H₂O₂ over a wide variety of titanium-silicate catalysts allowed us to infer requirements to an optimal catalyst and optimal reaction conditions for this reaction and to produce 2,3,5-trimethyl-1,4-benzoquinone (TMBQ, Vitamin E precursor) with nearly 100% selectivity at 100% substrate conversion. The main by-products in the TMP oxidation are C–C and C–O dimers, formed by coupling of intermediate phenoxyl radicals. The formation of TMBQ is favoured by (1) a poor coordinating solvent (MeCN), (2) elevated temperature (80 °C), (3) low TMP concentration (not higher than 0.1 M), (4) high H₂O₂/TMP molar ratio (ca. 3.5), and (5) low TMP/Ti ratio (<10–20). The crucial factors which determine the selectivity of Ti,Si-catalysts in TMP oxidation to TMBQ are mesoporosity and an optimal surface concentration (ca. 0.7–1.0 Ti atoms/nm²) of accessible highly dispersed, probably, dimeric Ti(IV) species. The catalysts prepared by a simple, affordable and cheap synthesis methodology via grafting titanium(IV) precursors onto the surface of commercial mesoporous silica completely fulfil these requirements and thus can be viewed as promising catalysts for environmentally benign TMBQ production.     

Effect of two cooking procedures on phytochemical compounds,total antioxidant capacity and colour of selected frozen vegetables

The effect of boiling and steaming on content of phytochemicals (carotenoids, chlorophylls, polyphenols and ascorbic acid) all evaluated by HPLC, total antioxidant capacity (TAC) measured by means of TEAC and FRAP assays and colour (L^∗, a^∗, b^∗, C, H°) of three frozen vegetables (carrot, cauliflower and spinach) was evaluated. Steaming increased the content of polyphenols in all vegetables and limited the depletion of carotenoids in spinach. Accordingly, TAC remained unvaried or increased both for steamed carrot and spinach. Boiling had a more marked effect on nutritional pattern of frozen vegetables in comparison with steaming, leading to a general loss of phytochemical compounds and TAC for all vegetables. Ascorbic acid was detected only in cauliflower and decreased after both treatments. Colour of frozen vegetables was only slightly influenced by cooking, probably due to blanching pre-treatment. Slight decrements of redness (a^∗) for carrot in relation with loss of carotenoids and greenness (−a^∗) for steamed spinach, due to a significant loss of total chlorophylls, were observed.     

Challenges to remote emergency decision-making for disasters or Homeland Security

New technology allows information gathering and collaboration across information networks that would be of benefit to emergency response. In a Homeland Security Exercise we compared the utility of fixed and mobile video and high quality still images on remote expert decision-making. Sixteen experts situated in three countries viewed and seven evaluated events of the exercise assisted by audio commentary of local knowledge experts. They evaluated the usefulness of black and white (B/W) compared to color images, fixed fast video versus slow video and still images. Technical difficulties interrupted image transmission to one remote site for half the Exercise. However, the images were found useful, color more so than B/W, mobile more so than fixed. The combination of still images and video was best. Playback of recorded images was especially useful for remote evaluation and decision-making. Improved reliability for these imaging technologies could improve shared awareness and large-scale coordination for Homeland Security events.     

Profound retroactive interference in anterograde amnesia: What interferes?

Objective: Anterograde amnesia is characterized by a profound inability to retain new information. Recent research suggests that at least some of this severe memory impairment may be the product of retroactive interference. What exactly interferes with memory in amnesic patients, however, remains unknown. The aim of the present study was to examine whether or not postlearning material which is highly dissimilar from the material to be remembered would interfere with amnesic patients' memory. Method: Prose retention was tested in 10 densely amnesic patients and 10 controls following a 10 minute delay period, which was either unfilled (minimal interference) or filled with a tone detection task in which participants were required to listen for piano notes (nonspecific interference). Results: A significant nonspecific retroactive interference effect was observed in the amnesic patients (p     

State space reduction by non-standard semantics for deadlock analysis

In recent years many techniques have been developed for automatically verifying concurrent systems and most of them are based on the representation of the concurrent system by means of a transition system. State explosion is one of the most serious problems of this approach: often the prohibitive number of states renders the verification inefficient and, in some cases, impossible.

We propose a method for reducing the state space of the transition system corresponding to a CCS process that suites deadlock analysis. The reduced transition system is generated by means of a non-standard operational semantics containing a set of rules which are, in some sense, an abstraction, preserving deadlock freeness, of the inference rules of the standard semantics. Our method does not build the standard transition system, but directly generates an abstract system with a fewer number of states, so saving memory space. We characterize a class of processes whose abstract transition system is not exponential in the number of parallel components.     

Predicting categorical forest variables using an improved k-Nearest Neighbour estimator and Landsat imagery

The k-Nearest Neighbour (k-NN) estimation and prediction technique is widely used to produce pixel-level predictions and areal estimates of continuous forest variables such as area and volume, often by sub-categories such as species. An advantage of k-NN is that the same parameters (e.g., k-value, distance metric, weight vector for the feature space variables) can be used for all variables, whether continuous or categorical. An obvious question is the degree to which accuracy can be improved if the k-NN estimation parameters are tailored for specific variable groups such as volumes by tree species or categorical variables. We investigated prediction of categorical forest attribute variables from satellite image spectral data using k-NN with optimisation of the weight vector for the ancillary variables obtained using a genetic algorithm. We tested several genetic algorithm fitness functions, all derived from well-known accuracy measures. For a Finnish test site, the categorical forest attribute variables were site fertility and tree species dominance, and for an Italian test site, the variables were forest type and conifer/broad-leaved dominance. The results for both test sites were validated using independent data sets. Our results indicate that use of the genetic algorithm to optimize the weight vector for prediction of a single forest attribute variable had a slight positive effect on the prediction accuracies for other variables. Errors can be further decreased if the optimisation is done by variable groups.     

Nicola Zabaglia and the School of Practical Mechanics of the Fabbrica of St. Peter’s in Rome

Nicola Zabaglia, master mason of the Fabbrica of St. Peter’s and inventor of many ingenious mechanical devices for restoration, was also the director of the “School of Practical Mechanics” for the education of young labourers. At a time when traditional operational experience was strongly rivalled by the coeval achievements in the theory of mechanics and its effect on building, the work of Zabaglia became an instrument of propaganda. Since empirical practice and the oral transmission of operational knowledge were called into question by the pressing progress of science as well as by new institutions, the works of Zabaglia and his talented students were not only an influential model of cohesion between architecture, building yard and applied mechanics, but also a melancholy epilogue of a practical tradition inexorably condemned to oblivion.