加速器驱动次临界系统的中高能质子轰击厚靶中子学实验研究

利用俄罗斯杜布纳联合核子研究所的高能加速器进行加速器驱动次临界系统 (ADS)靶区中子学研究。用 0 .5 33、1 .0、3.7和 7 4GeV质子轰击U(Pb)、Pb和Hg靶的测量结果表明 :U(Pb)和Pb与Hg靶的中子产额比分别为 ( 2 0 1± 0 1 0 )和 ( 1 76± 0 33) ,从获得较强中子的角度看 ,Hg作为ADS靶是不利的 ;沿厚 2 0cm靶的中子产额随入射质子穿透深度增大而下降 ,质子能量越低 ,中子产额下降越快 ,为在较大厚度范围内获得较均匀的中子场 ,质子能量不应低于 1GeV ;不同能量质子产生的次级中子能谱相近 ,但随质子能量提高 ,较高能量中子的比例逐渐增大。     

A second mutant allele (V199I) at the PRKAG3 (RN) locus- I. Effect on technological meat quality of pork loin

The effect of three alleles (RN(-), rn(+) and a second mutant allele V199I, denoted rn*) at the PRKAG3 (RN) locus on such meat quality traits as pH, internal reflectance (FOP), Warner-Bratzler shear force, water-holding capacity and cooking loss were studied. M. longissimus dorsi (LD) from a total of 334 crossbreed pigs, entire males and females, Hampshire (H) and Finnish Landrace (L) of three combinations H × LH, LH × H and LH × LH, were used. The PRKAG3 alleles were identified with a DNA test and all possible RN genotypes, RN(-)/RN(-) (23%), RN(-)/rn(+) (24%), RN(-)/rn* (33%), rn(+)/rn(+) (8%), rn(+)/rn* (9%) and rn*/rn* (2%), were found. Water, intramuscular fat, protein and glycogen contents were determined. All the three alleles at the RN locus affected the studied technological meat quality traits of pork loin, except for the internal reflectance 24 h post mortem and the shear force. The RN(-) allele was dominant over the other two alleles, rn(+) and rn*, in LD with regard to ultimate pH, water-holding capacity and cooking loss, giving lower ultimate pH and water-holding capacity and higher cooking loss. The rn* allele affected ultimate pH in LD of non-carriers of the RN(-) allele, giving higher ultimate pH. The RN(-) allele was also dominant over the other two alleles in residual glycogen content in entire male pigs, but not in female pigs, where the rn* allele had a glycogen-lowering effect. The water content was higher and the protein content lower in LD of all RN(-)/- animals compared with the other genotypes, while no significant differences were found with regard to IMF content. Water-holding capacity, cooking loss and shear force were higher in LD of entire males compared with females.     

Proton Conductive Membranes from Covalently Cross-Linked Poly(Acrylate)/Silica Interpenetrating Networks

The preparation of hybrid proton conductive membranes that comprise of covalently linked interpenetrating polymer and inorganic networks is reported. The hybrid membranes are synthesized via simultaneous photo-initiated polymerization and sol–gel processing. The simultaneous processing permeates fabrication of the membranes that comprises covalently cross-linked polymeric and inorganic networks. The membranes are characterized by attenuated total reflectance-Fourier transform infrared spectroscopy, scaning electron microsopy, thermogravimetric analysis, differential scanning calorimetry, in order to confirm their chemical composition, structure, and morphology. An addition of 3-methacryloxypropyl trimethoxysilane into the sol–gel composition allows the formation of covalent linkages between polymeric and inorganic networks, which facilitates a uniform distribution of the molecular components across the fabricated membranes. The incorporation of the silica network leads to an increase in water retention and proton conductivity of hybrid membranes as compared to their purely polymeric analogues.     

Age-Dependent Control of Collagen-Dependent Platelet Responses by Thrombospondin-1—Comparative Analysis of Platelets from Neonates,Children, Adolescents,and Adults

Platelet function is developmentally regulated. Healthy neonates do not spontaneously bleed, but their platelets are hypo-reactive to several agonists. The mechanisms underlying immature platelet function in neonates are incompletely understood. This critical issue remains challenging for the establishment of age-specific reference ranges. In this study, we evaluated platelet reactivity of five pediatric age categories, ranging from healthy full-term neonates up to adolescents (11–18 years) in comparison to healthy adults (>18 years) by flow cytometry. We confirmed that platelet hypo-reactivity detected by fibrinogen binding, P-selectin, and CD63 surface expression was most pronounced in neonates compared to other pediatric age groups. However, maturation of platelet responsiveness varied with age, agonist, and activation marker. In contrast to TRAP and ADP, collagen-induced platelet activation was nearly absent in neonates. Granule secretion markedly remained impaired at least up to 10 years of age compared to adults. We show for the first time that neonatal platelets are deficient in thrombospondin-1, and exogenous platelet-derived thrombospondin-1 allows platelet responsiveness to collagen. Platelets from all pediatric age groups normally responded to the C-terminal thrombospondin-1 peptide RFYVVMWK. Thus, thrombospondin-1 deficiency of neonatal platelets might contribute to the relatively impaired response to collagen, and platelet-derived thrombospondin-1 may control distinct collagen-induced platelet responses.     

Using extended siamese networks to provide decision support in aquaculture operations

Aquaculture as an industry is quickly expanding. As a result, new aquaculture sites are being established at more exposed locations previously deemed unfit because they are more difficult and resource demanding to safely operate than are traditional sites. To help the industry deal with these challenges, we have developed a decision support system to support decision makers in establishing better plans and make decisions that facilitate operating these sites in an optimal manner. We propose a case-based reasoning system called aquaculture case-based reasoning (AQCBR), which is able to predict the success of an aquaculture operation at a specific site, based on previously applied and recorded cases. In particular, AQCBR is trained to learn a similarity function between recorded operational situations/cases and use the most similar case to provide explanation-by-example information for its predictions. The novelty of AQCBR is that it uses extended Siamese neural networks to learn the similarity between cases. Our extensive experimental evaluation shows that extended Siamese neural networks outperform state-of-the-art methods for similarity learning in this task, demonstrating the effectiveness and the feasibility of our approach.

     

Effects of bolus injection duration on perfusion estimates in dynamic CT and dynamic susceptibility contrast MRI

Estimates of cerebral blood flow (CBF) and tissue mean transit time (MTT) have been shown to differ between dynamic CT perfusion (CTP) and dynamic susceptibility contrast MRI (DSC-MRI). This study investigates whether these discrepancies regarding CBF and MTT between CTP and DSC-MRI can be attributed to the different injection durations of these techniques. Five subjects were scanned using CTP and DSC-MRI. Region-wise estimates of CBF, MTT, and cerebral blood volume (CBV) were derived based on oscillatory index regularized singular value decomposition. A parametric model that reproduced the shape of measured time curves and characteristics of resulting perfusion parameter estimates was developed and used to simulate data with injection durations typical for CTP and DSC-MRI for a clinically relevant set of perfusion scenarios and noise levels. In simulations, estimates of CBF/MTT showed larger negative/positive bias and increasing variability for CTP when compared to DSC-MRI, especially for high CBF levels. While noise also affected estimates, at clinically relevant levels, the injection duration effect was larger. There are several methodological differences between CTP and DSC-MRI. The results of this study suggest that the injection duration is among those that can explain differences in estimates of CBF and MTT between these bolus tracking techniques.

     

Engineering TM1459 for Stabilisation against Inactivation by Amino Acid Oxidation

Oxidative alkene cleavage is a highly interesting reaction to obtain aldehydes and ketones. The Mn-dependent protein TM1459 from Thermotoga maritima can catalyse alkene cleavage of styrene derivatives in the presence of tert-butyl hydroperoxide. Despite the high thermal stability of the enzyme, it gets inactivated during the reaction. The data reported here indicate that auto-oxidation is responsible for the low stability of TM1459 in the oxidative environment required for the alkene cleavage reaction. By targeting the exchange of residues prone to oxidation, this phenomenon was successfully prevented. Importantly, the stability to oxidation conveyed by the amino acid exchanges led to increased enzyme activity. However, the exchanges resulted in slightly modified positions of two of the four metal-binding amino acids, thereby strongly impacting metal binding.     

Understanding the beliefs, actions and outcomes of sustainability reporting: An experimental approach

IS researchers have identified substantial research gaps within the IS community regarding sustainability. Therefore, this paper pursues an experimental approach to investigate online sustainability reports (SRs) which are a common instrument for corporate sustainability communication. The applied research approach examines not only which properties of SRs enhance the readers’ willingness to read a SR, but also to what extent SRs can influence the readers’ actions and impact corporate image. Within the course of this paper, a belief-action-outcome (BAO) model and a corresponding experimental design, which examines SRs in three phases (i.e. before reading, during reading and after reading), are developed and conducted; subsequently the results are empirically analysed. Finally, implications for practitioners and researchers in the field of sustainability and especially sustainability reporting are demonstrated. Furthermore, possible starting points for future research are discussed. The results indicate that a sophisticated SR that satisfies the readers’ expectations has a significant impact on corporate image and the readers’ actions (i.e. buying and recommending products, investing and considering to work for the reporting company), which qualifies sustainability reporting as an important channel for corporate communication.     

Diaspore Trait Preferences of Dispersing Ants

Elaiosomes of myrmecochorous plant seeds are known to enhance the attraction of diaspore-dispersing ants by serving as a nutritional reward. However, it remained unclear which (nutritional) compounds affect diaspore preferences of ants. We hypothesized that apart from elaiosome/seed-size ratio, volume, and physical surface of diaspores, the quantity and the composition of fatty acids, amino acids, and sugars strongly influence the diaspore preferences of different species. Chemical (nutritional) profiles as well as structural properties of seeds with and without elaiosomes were analyzed and correlated with observed seed choice behavior of ants. Cafeteria experiments in the field confirmed the enhanced attractiveness of elaiosome-bearing seeds for all three ant species tested (Lasius fuliginosus, Myrmica ruginodis, and Temnothorax nylanderi), although seeds lacking elaiosomes also were transported. In multiple-choice cafeteria experiments with simultaneously offered diaspores of 16 plant species with and without elaiosome and with highly varying structural and chemical properties, all three ant species showed distinct preferences for certain diaspore species. Correlation analyses confirmed that the presence of an elaiosome represents the crucial factor that favors ant diaspore dispersal. In addition, the composition and the content of free amino acids, and to varying degrees fatty acids, were found to significantly affect preferences of each ant species, whereas the effect of single fatty acids acting as chemical triggers for diaspore transport by ants, as supposed by several studies, was not confirmed. In conclusion, although at least some diaspore species lacking elaiosomes attract ants for diaspore removal services by presenting nutritional seed coats, the production of elaiosomes seems to provide a worthwhile investment. Elaiosomes ensure rapid diaspore detection and removal due to chemical cue compounds and by offering a highly nutritional food supply, probably fitting the nutritional demands of ants.     

Relaxation oscillations between Marangoni cells and double diffusive fingers in a reactive liquid–liquid system

We study a novel kind of coupling in chemo-hydrodynamic pattern formation driven by a neutralization reaction along a plane interface separating two immiscible liquid phases. The neutralization reaction, during which a surface-active carboxylic acid is converted into a surface-active salt, gives rise to numerous cycles of relaxation oscillations between a fast cellular Marangoni convection with parallel-acting density plumes and a slow finger convection. By means of particle image velocimetry the dynamics of the sub-structured Marangoni cells are characterized while their geometrical aspects are analysed using shadowgraphy. Based on concentration-dependent density measurements and experiments with miscible solutions, the finger convection could be clearly identified as a double-diffusive phenomenon. Furthermore, the interaction of the sub-structured Marangoni cells with the density effects is examined.