Downward comparison in everyday life: Reconciling self-enhancement models with the mood–cognition priming model.

Two models concerning downward comparison are motivational; they predict that when people are unhappy, they make downward comparisons to self-enhance (e.g., Wills, 1981). In contrast, the affect-cognition priming model (Wheeler & Miyake, 1992) predicts that unhappy people make upward comparisons because negative affect makes mood-congruent comparisons more accessible. The authors propose that both motivational and accessibility factors influence social comparisons. A study of undergraduates' self-recorded everyday comparisons supported this view. In addition, results (a) pointed to motivational influences other than self-enhancement and an accessibility influence other than mood-congruent priming, (b) suggested that motivated and unintended comparisons may differ somewhat in their susceptibility to motivational and accessibility influences, and (c) identified challenges to both self-enhancement and priming models. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Synthetic routes to lipidic diamines and amino alcohols: A class of potential antiinflammatory agents

Simple and efficient methods for the synthesis of lipidic amino alcohols and diamines are described in this paper. Lipidic 2-amino alcohols and 1,3-diamines can be synthesized starting from synthetic lipidic α-amino acids. Alternatively, commercially available lipidic 1,2-diols may be used as starting material for the synthesis of 2-amino alcohols. Initial experiments on the in vivo antiinflammatory activity of the compounds synthesized gave promising results.     

Fatty acid composition of ewe milk as affected by solar radiation and high ambient temperature

Forty lactating Comisana ewes were either exposed to or protected from solar radiation and fed either in the morning or afternoon during summer in a Mediterranean climate. Individual milk samples were taken on days 7, 21 and 42 of the study period to determine fatty acid composition by gas chromatography. Exposure to solar radiation resulted in higher proportions of short-chain and saturated fatty acids in milk, primarily because of increased contents of caproic, capric, lauric, myristic and stearic acids (by 3-18%), and decreased contents of oleic, linoleic and linolenic acids (by 2-9%). As a consequence, the long to short chain and the unsaturated to saturated fatty acid ratios were significantly higher by 4 and 13% respectively in the milk of the protected ewes compared with that of the exposed animals. Provision of shade also led to an increase in the 18:0+18:1 to 16:0 ratio, and to a decrease in the 12:0 + 14:0 + 16:0 fatty acid group, which are regarded as reliable indexes of the nutritional property of dietary fat in reducing cholesterol levels in human plasma. Feeding time had little impact on milk fat. Our findings suggest that high ambient temperature may markedly modify the lipid composition of ewe milk and that provision of shade, but not feeding management, can improve the milk fatty acid profile in dairy sheep raised in hot climates.     

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.     

On graph-based characteristics of optimal overlay topologies

In this paper, we address the challenge of overlay topology design by considering which overlay topology best minimizes cost function, taking into account overlay link creation cost and routing cost. First, we formulate the problem as Integer Linear Programming (ILP) given a traffic matrix and assuming cooperative behavior of nodes. Then, we propose some heuristics to find near-optimal overlay topologies with a reduced complexity. The solutions to the ILP problem on real network topologies have been analyzed, showing that the traffic demands between the nodes affect the decision to create new overlay links. Next, the obtained optimal and near-optimal overlay topologies are thoroughly analyzed and the heuristics are compared through extensive numerical evaluations. Finally guidelines for the selection of the best heuristic as a function of the cost parameters are also provided.     

困难会激发我们的创造力——Flickr创始人之一卡泰丽娜·费克访谈

2002年夏天,卡泰丽娜·费克(Caterina Fake)、斯图尔特·巴特菲尔德(StewartButterfield)和杰森·克拉森(Jason Classon)创办了网络软件公司Ludicorp。Ludicorp公司的第一款产品是永不结束的游戏(Game Neverending),这是一种大型的多人在线角色扮演游戏。在2004年,他们为原来的游戏增加了一个新功能,就是即时交换照片功能的多人聊天室,正是这项新的功能,使得这款游戏迅速火爆起来,新加功能的受欢迎程度甚至超过了游戏本身。此时,整个开发团队意识到了其间的价值,于是他们决定抓住永不结束的游戏这个机会,在其基础上开发一款新的照片交换社区网站,网站的名字就叫做Flickr。果然,Flickr迅速崛起,成为最著名的Web2.0公司之一。尽管它在2005年3月被雅虎公司所收购,但卡泰丽娜·费克的创业激情永远不会停止。     

Evaluating stranger policies in P2P file-sharing systems with reciprocity mechanisms

How to deal with strangers efficiently is a big challenge for designing P2P systems, as ineffective stranger policies will cause the degradation of system performance and fairness. In this work, we focus on an open P2P file-sharing environment with reciprocity incentive mechanisms, and we evaluate the impact of different stranger policies to system performance and fairness using both numerical analyses and agent-based simulations. The results reveal that there exist tradeoffs between system performance and fairness; the optimal performance and fairness of the system cannot be reached simultaneously; free-riders will survive when system performance is optimal. The accuracy of this evaluation is verified through the analysis of stranger policies in BitTorrent and eMule/eDonkey. Therefore, this evaluation can effectively help P2P designers select appropriate stranger policies according to their individual design goals.     

Antiproliferative Effects of St. John’s Wort,Its Derivatives,and Other Hypericum Species in Hematologic Malignancies

Hypericum is a widely present plant, and extracts of its leaves, flowers, and aerial elements have been employed for many years as therapeutic cures for depression, skin wounds, and respiratory and inflammatory disorders. Hypericum also displays an ample variety of other biological actions, such as hypotensive, analgesic, anti-infective, anti-oxidant, and spasmolytic abilities. However, recent investigations highlighted that this species could be advantageous for the cure of other pathological situations, such as trigeminal neuralgia, as well as in the treatment of cancer. This review focuses on the in vitro and in vivo antitumor effects of St. John’s Wort (Hypericum perforatum), its derivatives, and other Hypericum species in hematologic malignancies. Hypericum induces apoptosis in both myeloid and lymphoid cells. Other Hypericum targets include matrix metalloproteinase-2, vascular endothelial growth factor, and matrix metalloproteinase-9, which are mediators of cell migration and angiogenesis. Hypericum also downregulates the expression of proteins that are involved in the resistance of leukemia cells to chemotherapeutic agents. Finally, Hypericum and its derivatives appear to have photodynamic effects and are candidates for applications in tumor photodynamic therapy. Although the in vitro studies appear promising, controlled in vivo studies are necessary before we can hypothesize the introduction of Hypericum and its derivatives into clinical practice for the treatment of hematologic malignancies.     

New MPLS network management techniques based on adaptive learning

The combined use of the differentiated services (DiffServ) and multiprotocol label switching (MPLS) technologies is envisioned to provide guaranteed quality of service (QoS) for multimedia traffic in IP networks, while effectively using network resources. These networks need to be managed adaptively to cope with the changing network conditions and provide satisfactory QoS. An efficient strategy is to map the traffic from different DiffServ classes of service on separate label switched paths (LSPs), which leads to distinct layers of MPLS networks corresponding to each DiffServ class. In this paper, three aspects of the management of such a layered MPLS network are discussed. In particular, an optimal technique for the setup of LSPs, capacity allocation of the LSPs and LSP routing are presented. The presented techniques are based on measurement of the network state to adapt the network configuration to changing traffic conditions.