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1.
We add to the investments literature by employing new techniques to estimate asset performance. We estimate a data envelopment analysis based efficiency score that allows for direct comparison between ex-post efficiency rankings and test the ex-ante relevance of such scores by including them into asset pricing models. We find that knowing the fund efficiency score can help explain time-series returns. When efficiency is included in an asset pricing model, the absolute value of the average mispricing error is decreased, which we take as evidence of the explanatory power of efficiency scores. But more importantly, we show that efficacy scores can be used as next period predictors of stock returns. In addition, we further use the efficiency scores to differentiate between the performance of constrained and unconstrained investment assets, as in the case of socially responsible investments. Our findings give robustness to the literature on constrained investments showing significant underperformance of socially and responsible investments.  相似文献   

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We consider the model of exact learning using an equivalence oracle and an incomplete membership oracle. In this model a random subset of the learners membership queries is left unanswered. Our results are as follows. First, we analyze the obvious method for coping with missing answers: search exhaustively through all possible answer patterns associated with the unanswered queries. Thereafter, we present two specific concept classes that are efficiently learnable using an equivalence oracle and a (completely reliable) membership oracle, but are provably not polynomially learnable if the membership oracle becomes slightly incomplete. The first class demonstrates that the aforementioned method of exhaustively searching through all possible answer patterns cannot be substantially improved in general (despite its apparent simplicity). The second class demonstrates that the incomplete membership oracle can be rendered useless even if it leaves only a fraction 1/poly(n) of all queries unanswered. Finally, we present a learning algorithm for monotone DNF formulas that can cope with a relatively large fraction of missing answers (more than 60%), but is as efficient (in terms of run-time and number of queries) as the classical algorithm whose questions are always answered reliably.  相似文献   

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Small shifts in circadian timing occur frequently as a result of daylight saving time or later weekend sleep. These subtle shifts in circadian phase have been shown to influence subjective sleepiness, but it remains unclear if they can significantly affect performance. In a retrospective analysis we examined performance on the Psychomotor Vigilance Test before bedtime and after wake time in 11 healthy adults on fixed sleep schedules based on their habitual sleep times. The dim light melatonin onset, a marker of circadian timing, was measured on two occasions. An average 1.1?h shift away from a proposed optimal circadian phase angle (6?h between melatonin onset and midpoint of sleep) significantly slowed mean, median and fastest 10% reaction times before bedtime and after wake time (p?相似文献   

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Search engines play a critical role in the diffusion of online information because they determine what content is easily visible to Web users. Major search engines, such as Google, Microsoft Live Search, and Yahoo!, provide two distinct types of results, organic and paid, each of which uses different mechanisms for selecting and ranking relevant Web pages. Using a third-party trust assurance program from BBB (Better Business Bureau) Online we find that vendors represented by websites in organic and paid results have varying reliability ratings. These ratings, based on overall customer experiences, may range from satisfactory to unsatisfactory. We empirically examine how vendors' reliability ratings from BBB Online are associated with cues (such as type of search result, relative price of a product, and number of sites selling the product) that can be observed or derived from organic and paid search results. Further, we apply a data mining technique to predict the vendors' BBB reliability ratings using those cues and achieve good performance.  相似文献   

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Quantum teleportation of an unknown quantum state is one of the few communication tasks which has no classical counterpart. Usually the aim of teleportation is to send an unknown quantum state to a receiver. But is it possible in some way that the receiver’s state has more quantum discord than the sender’s state? We look at a scenario where Alice and Bob share a pure quantum state and Alice has an unknown quantum state. She performs joint measurement on her qubits and channel to prepare Bob’s qubits in a mixed state which has higher quantum discord than hers. We also observe an interesting feature in this scenario, when the quantum discord of Alice’s qubits increases, then the quantum discord of Bob’s prepared qubits decreases. Furthermore, we show that the fidelity of one-qubit quantum teleportation using Bob’s prepared qubits as the channel is higher than using Alice’s qubits.  相似文献   

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Glycosyl hydrolases catalyse the acid hydrolysis of the glycosidic bond of glycans. The structure of barley beta-D-glucan glucohydrolase in complex with a thiol substrate analogue presents very short contacts between the carboxyl oxygen atoms of the catalytic acid and the sulphur atom of the inhibitor. The geometries of acetic acid and dimethylsulfide in various ionisation states from ab initio molecular orbital calculations predict similar short contacts when an acetate anion forms a complex with a sulphonium cation. The energy of this complex is, however, significantly greater than the energy of the complex where both acetic acid and dimethylsulfide are neutral. Calculations on an active site model of barley beta-D-glucan glucohydrolase indicate that the protein environment is able to significantly reduce this energy. The energy required for mechanical constraint of the short S...O separations, however, is identical to that required for the transfer of the proton from the acid to the sulphur. The identity of the species participating in the short contacts remains unanswered.  相似文献   

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Although autonomous vehicles are increasingly becoming a reality, eliminating human intervention from driving may imply significant safety and trust-related concerns. To address this issue from a psychological perspective, this study applies layers of anthropomorphic cues to an artificial driving agent and explicates the process in which these cues promote positive evaluations and perceptions of an unmanned driving system. In a between-subjects factorial experiment (N = 89) consisting of three unmanned driving scenarios, participants interacted with an artificial driving agent with different levels of anthropomorphic cues induced by the variations in appearance (human-like vs. gadget-like) and autonomy (high vs. low) of the agent. The results indicated that human-like appearance and high autonomy were more effective in eliciting positive perceptions of the agent. In addition, a mediation analysis revealed that the greater level of anthropomorphism induced by human-like appearance and high autonomy in the agent evoked the feelings of social presence, which in turn positively affected the perceived intelligence and safety of and trust in the agent, suggesting that the extent to which users perceive the driving agent as intelligent, safe, and trustworthy is largely determined by the feelings of social presence experienced during their interaction.  相似文献   

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Recently, applied mathematicians have been pursuing the goal of sparse coding of certain mathematical models of images with edges. They have found by mathematical analysis that, instead of wavelets and Fourier methods, sparse coding leads towards new systems: ridgelets and curvelets. These new systems have elements distributed across a range of scales and locations, but also orientations. In fact they have highly direction-specific elements and exhibit increasing numbers of distinct directions as we go to successively finer scales. Meanwhile, researchers in natural scene statistics (NSS) have been attempting to find sparse codes for natural images. The new systems they have found by computational optimization have elements distributed across a range of scales and locations, but also orientations. The new systems are certainly unlike wavelet and Gabor systems, on the one hand because of the multi-orientation and on the other hand because of the multi-scale nature. There is a certain degree of visual resemblance between the findings in the two fields, which suggests the hypothesis that certain important findings in the NSS literature might possibly be explained by the slogan: edges are the dominant features in images, and curvelets are the right tool for representing edges. We consider here certain empirical consequences of this hypothesis, looking at key findings of the NSS literature and conducting studies of curvelet and ridgelet transforms on synthetic and real images, to see if the results are consistent with predictions from this slogan. Our first experiment measures the nonGaussianity of Fourier, wavelet, ridgelet and curvelet coefficients over a database of synthetic and photographic images. Empirically the curvelet coefficients exhibit noticeably higher kurtosis than wavelet, ridgelet, or Fourier coefficients. This is consistent with the hypothesis. Our second experiment studies the inter-scale correlation of wavelet coefficient energies at the same location. We describe a simple experiment showing that presence of edges explains these correlations. We also develop a crude nonlinear 'partial correlation' by considering the correlation between wavelet parents and children after a few curvelet coefficients are removed. When we kill the few biggest coefficients of the curvelet transform, much of the correlation between wavelet subbands disappears--consistent with the hypothesis. We suggest implications for future discussions about NSS.  相似文献   

11.
Despite massive efforts, proteomics has not delivered biomarkers of clinical value. However, the technologies that are emerging today have the power to reach deep into proteomes and identify the patterns associated with different diseases. Study design is then crucial and sample quality, bioinformatics approaches, prevalidation, using independent patient cohort need to attract increased attention before proteomics will contribute to the needs of personalized medicine.  相似文献   

12.
Feng  Shuo  He  Xinjing  He  Weiping  Billinghurst  Mark 《Virtual Reality》2023,27(2):591-601
Virtual Reality - Most augmented reality (AR) assembly guidance systems only utilize visual information. Regarding the sound, the human binaural effect helps users quickly identify the general...  相似文献   

13.
The development within the mobile communications industry has provided a new mechanism for individuals to watch television programs via mobile device, known as mobile television (m-TV). Considering that m-TV is an emerging technology among traditional television services where critical success factors depend on user-centered, it is important to understand users' behavioral intention (BI). Unlike previous studies which have mainly focused on flow experience, perceived value, motivation and social cognitive theories, this study examines user-centered factors of technology readiness (TR) and technical support and training (TST). Therefore, 244 valid data were tested using partial least squares structural equation modeling (PLS-SEM) to measure both reflective and formative constructs based on the proposed framework. Findings reported that performance expectancy (PE), effort expectancy (EE) and TST have a positive and significant impact on BI. TR however has a negative relationship with BI. In addition, TR was also found to influence PE and EE. Similarly, TST has a direct effect factor on EE and EE was a significant determinant of PE. The findings of this study not only provide guidance for future researchers, but also valuable insights for designers, marketers and system providers of m-TV to tailor their services in the near future.  相似文献   

14.
This article presents the information-theoretic based feature information interaction, a measure that can describe complex feature dependencies in multivariate settings. According to the theoretical development, feature interactions are more accurate than current, bivariate dependence measures due to their stable and unambiguous definition. In experiments with artificial and real data we compare first the empirical dependency estimates of correlation, mutual information and 3-way feature interaction. Then, we present feature selection and classification experiments that show superior performance of interactions over bivariate dependence measures for the artificial data, for real world data this goal is not achieved yet.
Stéphane Marchand-MailletEmail:
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In an explorative task subjects were asked to track a line presented in combination with other confusing lines on a 3D display. 24 subjects performed the explorative task under three depth cue conditions which were: stereopsis, movement parallax or a combination of stereopsis and movement parallax (stereo and parallax).

Task performance was assessed by recording completion time and correctness of answer.

The combination of stereopsis and movement parallax gave rise to highest percentage of correct answers (84%), followed by the condition where movement parallax was the only depth cue (80%). Percentage of correct answers in both conditions was found to be significantly higher than it was in the condition with stereopsis (60%).

Mean completion time was about the same in the stereo and parallax condition and the stereopsis condition. Compared to the movement parallax condition both means were significantly decreased.

Accuracy in completing the task was found to be similar in 3D displays enabling movement parallax and in 3D displays presenting stereoscopic images.  相似文献   


17.
Should an intelligent software tutor be polite, in an effort to motivate and cajole students to learn, or should it use more direct language? If it should be polite, under what conditions? In a series of studies in different contexts (e.g., lab versus classroom) with a variety of students (e.g., low prior knowledge versus high prior knowledge), the politeness effect was investigated in the context of web-based intelligent tutoring systems, software that runs on the Internet and employs artificial intelligence and learning science techniques to help students learn. The goal was to pinpoint the appropriate conditions for having the web-based tutors provide polite feedback and hints (e.g., “Let’s convert the units of the first item”) versus direct feedback and hints (e.g., “Convert the units of the first item now”). In the study presented in this paper, 132 high school students in a classroom setting, grouped as low and high prior knowledge learners according to a pre-intervention knowledge questionnaire, did not benefit more from polite feedback and hints than direct feedback and hints on either an immediate or delayed posttest, both of which contained near transfer and conceptual test items. Of particular interest and contrary to an earlier lab study, low prior knowledge students did not benefit more from using the polite version of a tutor. On the other hand, a politeness effect was observed for the students who made the most errors during the intervention, a different proxy for low prior knowledge, hinting that even in a classroom setting, politeness may be beneficial for more needy students. This article presents and discusses these results, as well as discussing the politeness effect more generally, its theoretical underpinnings, and future directions.  相似文献   

18.
As companies move increasingly toward text-based computer-mediated communications (CMC) for providing customer service, they tend to lose out on the social presence of a live agent interacting in person or via the telephone. Given the importance of social presence for maintaining healthy customer relations, how can companies counter the relative lack of social presence in CMC? Increasing the synchronicity of communications is one solution, but it is not always possible to provide instant responses to customers. In such cases, can a richer modality (e.g., picture of the customer-service agent) make up for diminished synchronicity and thereby enhance social presence? We addressed these questions with a 3 [synchronicity: high (no delay in response time) vs. medium (1-h delay) vs. low (6-h delay)] × 3 [modality: text-only vs. text+picture vs. text+emoticon] ful factorial, between-subjects experiment in which participants (N = 108) interacted with a customer service agent in a mobile e-commerce context. Data reveal that participants in high synchronicity and text+emoticon conditions felt higher social presence and perceived the customer service agent more positively than those in other conditions. Social presence and task impression mediated the relationship between each independent variable and their evaluations of the customer service agent.  相似文献   

19.
The present study investigates how the perceived congruity (the perceived level of fit between the execution of the in-game ad and the game environment) of in-game advertising (IGA) in fantasy games affects both players' attitude towards the IGA and their play intention of the fantasy game in which it is embedded, and how these effects are moderated by perceived IGA interactivity. An experimental study with actual fantasy game players (N = 619) following a 2 (Congruent IGA − Incongruent IGA) × 2 (Interactive IGA – Non-interactive IGA) between-subjects design was conducted. The results indicate that the perceived congruity of IGA reduces the perceived intrusiveness of the IGA and positively contributes to the perceived realism of the fantasy game. Intrusiveness and realism, in turn, influence players’ attitude towards the IGA and their play intention of the fantasy game. Whilst the positive effect of perceived congruity through intrusiveness is reinforced by the perceived interactivity of the IGA, the effect of perceived congruity through realism is attenuated by perceived interactivity.  相似文献   

20.
Prior research on digital games illustrates a perceived gender gap in participation and performance, suggesting men as playing more and better than women. This article challenges the gender gap using longitudinal behavioral data of men and women in 2 MMOs in the United States and China. Results show that women advance at least as fast as men do in both games. Thus, perceived gender‐based performance disparities seem to result from factors that are confounded with gender (i.e., amount of play), not player gender itself. We conclude that the stereotype of female players as inferior is not only false, but also a potential cause for unequal participation in digital gaming.  相似文献   

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