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1.
Simultaneous recordings were collected from between two and four buildup neurons from the left and right superior colliculi in rhesus monkeys in a simple two-choice brightness discrimination task. The monkeys were required to move their eyes to one of two response targets to indicate their decision. Neurons were identified whose receptive fields were centered on the response targets. The functional role of inhibition was examined by conditionalizing firing rate on a high versus low rate in target neurons 90 ms to 30 ms before the saccade and examining the firing rate in both contralateral and ipsilateral neurons. Two models with racing diffusion processes were fit to the behavioral data, and the same analysis was performed on simulated paths in the diffusion processes that have been found to represent firing rate. The results produce converging evidence for the lack of a functional role for inhibition between neural populations corresponding to the two decisions. 相似文献
2.
Quantum discord, as a measure of all quantum correlations, has been proposed as the key resource in certain quantum communication tasks and quantum computational models without containing much entanglement. Daki? et al. (Phys Rev Lett 105:190502, 2010) introduced a geometric measure of quantum discord (GMQD) and derived an explicit formula for any two-qubit state. Luo and Fu (Phys Rev A 82:034302, 2010) introduced another form of GMQD and derived an explicit formula for arbitrary state in a bipartite quantum system. However, the explicit analytical expression for any bipartite system was not given. In this work, we give out the explicit analytical expressions of the GMQD for a two-parameter class of states in a qubit–qutrit system and study its dynamics for the states under various dissipative channels in the first time. Our results show that all these dynamic evolutions do not lead to a sudden vanishing of GMQD. Quantum correlations vanish at an asymptotic time for local or multi-local dephasing, phase-flip, and depolarizing noise channels. However, it does not disappear even though t → ∞ for local trit-flip and local trit-phase-flip channels. Our results maybe provide some important information for the application of GMQD in hybrid qubit–qutrit systems in quantum information. 相似文献
3.
Quantum computation, in particular Grover’s algorithm, has aroused a great deal of interest since it allows for a quadratic
speed-up to be obtained in search procedures. Classical search procedures for an N element database require at most O( N) time complexity. Grover’s algorithm is able to find a solution with high probability in ){O(\sqrt{N})} time through an amplitude amplification scheme. In this work we draw elements from both classical and quantum computation
to develop an alternative search proposal based on quantum entanglement detection schemes. In 2002, Horodecki and Ekert proposed
an efficient method for direct detection of quantum entanglement. Our proposition to quantum search combines quantum entanglement
detection alongside entanglement inducing operators. The quantum search algorithm relies on measuring a quantum superposition
after having applied a unitary evolution. We deviate from the standard method by focusing on fine-tuning a unitary operator
in order to infer the solution with certainty. Our proposal sacrifices space for speed and depends on the mathematical properties
of linear positive maps Λ which have not been operationally characterized. Whether such a Λ can be easily determined remains
an open question. 相似文献
4.
This paper aims to provide a basis for renewed talk about use in computing. Four current discourse arenas are described. Different intentions manifest in each arena are linked to failures in translation, different terminologies crossing disciplinary and national boundaries non-reflexively. Analysis of transnational use discourse dynamics shows much miscommunication. Conflicts like that between the Scandinavian System Development School and the usability approach have less current salience. Renewing our talk about use is essential to a participatory politics of information technology and will lead to clearer perception of the implications of letting new systems becoming primary media of social interaction. 相似文献
6.
We investigated the effect of an elevated ambient temperature on performance in a persistence task. The task involved the coding of incorrect symbols and participants were free to decide how long to spend performing this task. Applying a between-subject design, we tested 125 students in an office-like environment in one of the three temperature conditions. The comfort condition (Predicted Mean Vote [PMV] = 0.01) featured an average air temperature of 24 °C. The elevated ambient temperature condition was 28 °C (PMV = 1.17). Condition three employed an airstream of approximately 0.8 m/s, intended to compensate for performance decrements at the elevated air temperature (28 °C, PMV = 0.13), according to Fanger’s thermal comfort equation. Participants in the warm condition were significantly less persistent compared with participants in the control and compensation conditions. As predicted by the thermal comfort equation, the airstream seemed to compensate for the higher temperature. Participants’ persistence in the compensation and comfort conditions did not differ. Practitioner Summary: A laboratory experiment involving a simulated office environment and three ambient temperature conditions (24 °C, 28 °C and 28 °C plus airstream) showed that persistence at a task is significantly impaired at 28 °C. An airstream of 0.8 m/s at 28 °C compensated for the disinclination to persist with the task. 相似文献
7.
The disrupting effect of quantum noise on the dynamics of a spatial quantum formulation of the iterated prisoner’s dilemma game with variable entangling is studied in this work. The game is played in the cellular automata manner, i.e., with local and synchronous interaction. It is concluded in this article that quantum noise induces in fair games the need for higher entanglement in order to make possible the emergence of the strategy pair ( Q, Q), which produces the same payoff of mutual cooperation. In unfair quantum versus classic player games, quantum noise delays the prevalence of the quantum player. 相似文献
8.
A natural extension of cloud services is to extend platform independence via virtualization to a security model. For security as a service to be a viable cloud offering, customers must be able to establish their own security policies and risk framework. Today, cloud customers must purchase, install, and configure the antiviral, antispyware, antimalware, and so on, services in their host environment. However, if cloud providers offered security as a service in these virtualized environments, customers could integrate these security measures into their risk profile to ensure that the cloud risk posture is acceptable for their mission. By leveraging the service delivery model, a cloud can deliver security as a service as part of a virtualized infrastructure as a pay-for-service offering. This configuration lets customers selectively choose the countermeasures they wish to implement as dictated by their risk profile. The practicality of this security-as-a-service approach will continue to evolve with technology. In spring 2009, VMware released the VMsafe API, which supports third-party security applications in the hypervisor (a virtual-machine monitor). If VMsafe performs as claimed, it will enable the cloud-computing environment to support security as a service. The VMsafe API offers the immediate opportunity to begin the long-needed transition of cloud computing from a trusted environment to a secured environment. 相似文献
9.
This article explores a robotogenetic model of empathetic understanding of another mind as one of the capabilities required in human–robot social interactions. The term robotogenetic means that we implement a possible ontogeny (i.e., developmental process) of the social capability onto a robotic embodiment with a certain phylogenetic background (i.e., innate prerequisites). First, we look into infants development of social and communicative skills, especially of empathetic understanding of others. We then consider two fundamental abilities, namely eye-contact and joint attention, as the prerequisites for this cognitive development. Then in psychological experiments using robots that are capable of eye-contact and joint attention, we observe how people, especially infants and children, attribute mental states to the robots. Based on these investigations, we consider a possible mechanism of empathy which is based on the spatiotemporal coordination of attention and bodily movement between the self and another.This work was presented in part at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January 24–26, 2003 相似文献
10.
Interactive whiteboards (IWBs) have been widely introduced to English primary schools (5–11 years) in the last decade and
this has generated much research interest. In the past, research has focused on IWB-use in teacher-led sessions, attending
particularly to the nature of teacher-pupil interaction at the IWB and the apparent motivational advantages for children.
In contrast, this study focuses on children’s communication and thinking during their semi-autonomous use of the IWB during
collaborative groupwork in primary school science lessons, aiming in part to see if the IWB is suited to this type of use.
Over the course of one school year, twelve primary teachers of Years 4 and 5 (8–10 years) took part in a professional development
and research programme which involved them in devising a sequence of three science lessons incorporating small-group activity
at the IWB. The functionality of the IWB is analysed here as means for supporting the children’s joint communication and thinking,
using embedded cues and the availability of certain features in the IWB technology. Our observational analysis of two examples
of children’s collaborative activity in different classrooms, together with subsequent group interviews, suggests that the
IWB can make some identifiable contributions to children’s productive communication and thinking. However the IWB is not seen
to be an entirely distinctive or pedagogically transformative learning resource in the primary classroom. In our developing
conceptual framework, the children’s knowledge building is closely related to their active engagement in using IWB affordances
and their productive dialogue, essentially supported by the teacher’s scaffolding strategies, the establishment and use of
“talk rules” in conversation, and the opportunities and constraints applying in classroom participation structures. These
conditions help the children to deal with interconnected social, cognitive, and technical problems arising over time. Certain
aspects of this form of computer-supported collaborative learning (CSCL) are discussed. These relate to the integration of
the IWB with other classroom learning systems and resources, and to the nature of progression in children’s activity and learning
with this new type of highly integrated system of CSCL. 相似文献
11.
This research was designed to objectively investigate the desired low back (lumbar) support in a task chair; specifically by allowing a user to self-select the magnitude and location of support. An experimental chair built specifically for this study allowed the users to remotely adjust 35 diodes to achieve their desired level of support. Pressure mapping was used to measure the interface pressure at the user–seat back interface. It was determined that 73.8% of the 201 participants in this study, self-selected asymmetrical lower back support that was at least 20% greater on one side vs. the other. Additionally, 16.9% of the participants self-selected support on one side which was at least twice that of the other side. Contrary to popular practice, participants were found to prefer asymmetric support in the lower back region. It is anticipated that the culmination of this research will aid chair manufacturers in designing adaptable back rests. Practitioner Summary: Most current lumbar supports are designed to move vertically and to symmetrically increase or decrease in firmness as per a user’s adjustment. This investigation highlights that participants tended to select asymmetrical lumbar support, and as such, designers should consider providing lumbar supports that provide the desired support at appropriate locations. 相似文献
12.
This study investigates whether night-time light images acquired from the Defense Meteorological Satellite Program’s Operational Linescan System provide spatial and temporal insight with regard to the humanitarian aspects of the Syrian crisis. Evaluating the ongoing crisis in Syria is challenging since reliable witness reports are hard to gather in a war zone. Therefore satellite images, as one of the few sources of objective information, are potentially of great importance. We used 38 monthly Defense Meteorological Satellite Program’s Operational Linescan System composites covering the period between January 2008 and February 2014. The results indicate that night-time light and lit area in Syria declined by about 74% and 73%, respectively, between March 2011 and February 2014. In 12 of 14 provinces, night-time light declined by >60%. Damascus and Quneitra are the exceptions, with night-time light having declined only by about 35%. Notably, the number of internally displaced persons (IDPs) of each province shows a linear correlation with night-time light loss, with an R2 value of 0.52. Through clustering the time series images, we found that the international border of Syria represents a distinct boundary between regions of differing night-time light spatiotemporal patterns. The contrast across the border increases as the region studied encompasses a wider zone on either side of the border. These findings lend support to the hypothesis that night-time light can be a useful source for monitoring humanitarian crises such as that unfolding in Syria. 相似文献
13.
Media richness theory has been an influential deterministic theory of communication media adoption and use since its development in the mid-1980s. However, there has been mounting evidence, particularly in the 1990s, that predictions based on the media richness theory do not always hold. For example, there has been evidence that a lean communication medium can be the choice of groups engaged in complex tasks, such as strategic decision making, even when richer media are available. The two main shortcomings of most studies aimed at testing the media richness theory have been: (a) an orientation toward controlled settings, which hampers the drawing of implications for the usually `non-controlled' situations found in organizations in general; and (b) a focus on media adoption patterns, which has led to lack of evidence regarding group task outcomes. Here, we go some way towards filling this research gap by providing evidence that non-controlled groups can voluntarily adopt a communication medium that they perceive as lean. Moreover, we show that, due to a perception of the limitations imposed by the medium, group members can adapt their behavior in order to overcome such limitations, producing outcomes whose quality is perceived as higher by them than in richer media. We studied five process improvement groups in a New Zealand university. The groups, which redesigned typical university processes, voluntarily conducted most of their interactions through an e-mail conferencing system developed by the author. 相似文献
14.
Can we determine a high resolution protein structure quickly, say, in a week? I will show this is possible by the current technologies together with new computational tools discussed in this article. We have three potential paths to explore: - X-ray crystallography. While this method has produced the most protein structures in the PDB (Protein Data Bank), the nasty trial-and-error crystallization step remains to be an inhibitive obstacle.
- NMR (Nuclear Magnetic Resonance) spectroscopy. While the NMR experiments are relatively easy to do, the interpretation of the NMR data for structure calculation takes several months on average.
- In silico protein structure prediction. Can we actually predict high resolution structures consistently? If the predicted models remain to be labeled as “predicted”, and these structures still need to be experimentally verified by the wet lab methods, then this method at best can serve only as a screening tool.
I investigate the question of “quick protein structure Determination” from a computer scientist point of view and actually answer the more relevant question “what can a computer scientist effectively contribute to this goal”. 相似文献
15.
This paper examines whether improving physical ergonomics working conditions affects worker productivity in a call centre with computer-intensive work. A field study was conducted at a catalogue retail service organization to explore the impact of ergonomics improvements on worker production. There were three levels of ergonomics interventions, each adding incrementally to the previous one. The first level was ergonomics training for all computer users accompanied by workstation ergonomics analysis leading to specific customized adjustments to better fit each worker (Group C). The second level added specific workstation accessories to improve the worker fit if the ergonomics analysis indicated a need for them (Group B). The third level met Group B requirements plus an improved chair (Group A). Productivity data was gathered from 72 volunteer participants who received ergonomics improvements to their workstations and 370 control subjects working in the same departments. Daily company records of production outputs for each worker were taken before ergonomics intervention (baseline) and 12 months after ergonomics intervention. Productivity improvement from baseline to 12 months post-intervention was examined across all ergonomics conditions combined, and also compared to the control group. The findings showed that worker performance increased for 50% of the ergonomics improvement participants and decreased for 50%. Overall, there was a 4.87% output increase for the ergonomics improvement group as compared to a 3.46% output decrease for the control group. The level of productivity increase varied by the type of the ergonomics improvements with Group C showing the best improvement (9.43%). Even though the average production improved, caution must be used in interpreting the findings since the ergonomics interventions were not successful for one-half of the participants. 相似文献
16.
Elite police work has bursts of intense physically demanding work requiring high levels of fitness, or capacity, and movement competency; which are assumed to increase one's injury resilience. The purpose of this study was to follow members of an elite police force ( N = 53) to test whether back injuries ( N = 14) could be predicted from measures of fitness and movement quality. Measures of torso endurance, relative and absolute strength, hip ROM and movement quality using the Functional Movement Screen TM and other dynamic movement tests were obtained from every officer at baseline. When variables were grouped and considered holistically, rather than individually, back injury could be predicted. Seven variables best predicted those who would suffer a back injury (64% sensitivity and 95% specificity for an overall concordance of 87%). Overall, the ability to predict back injury was not high, suggesting that there is more complexity to this relationship than is explained with the variables tested here. Practitioner Summary: Members of elite police forces have exposure to intense physically demanding work. Increased levels of fitness and movement competency have been assumed to increase injury resilience. However, complexity in the interactions between exposure, movement competency, training, fitness and injury may occlude the true relationship between these variables. 相似文献
17.
The ‘looked-but-failed-to-see’ phenomenon is crucial to driving safety. Previous research utilising change detection tasks related to driving has reported inconsistent effects of driver experience on the ability to detect changes in static driving scenes. Reviewing these conflicting results, we suggest that drivers' increased ability to detect changes will only appear when the task requires a pattern of visual attention distribution typical of actual driving. By adding a distant fixation point on the road image, we developed a modified change blindness paradigm and measured detection performance of drivers and non-drivers. Drivers performed better than non-drivers only in scenes with a fixation point. Furthermore, experience effect interacted with the location of the change and the relevance of the change to driving. These results suggest that learning associated with driving experience reflects increased skill in the efficient distribution of visual attention across both the central focus area and peripheral objects. 相似文献
18.
Words set in capital letters are less legible than in lower case when reading text, searching for newspaper headlines, or finding a name on a map. The difference is usually attributed to the distinctive shape of lower case words, but lower case setting also emphasises capital letters at the start of sentences and for proper names. In the experiment reported here people searched for names on a map-like display. Names set entirely in lower case (eg, southampton) took significantly longer to find than those set in small capitals with a large initial capital (eg, Southampton) and so, for this task, emphasis given to the initial letter is clearly more important than word shape. This calls into doubt the world shape explanation in other contexts. 相似文献
19.
The behavior of total quantum correlations (discord) in dimers consisting of dipolar-coupled spins 1/2 are studied. We found that the discord $Q=0$ at absolute zero temperature. As the temperature $T$ increases, the quantum correlations in the system increase at first from zero to its maximum and then decrease to zero according to the asymptotic law $T^{-2}$ . It is also shown that in absence of external magnetic field $B$ , the classical correlations $C$ at $T\rightarrow 0$ are, vice versa, maximal. Our calculations predict that in crystalline gypsum $\hbox {CaSO}_{4}\cdot \hbox {2H}_{2}{\hbox {O}}$ the value of natural $(B=0)$ quantum discord between nuclear spins of hydrogen atoms is maximal at the temperature of 0.644 $\upmu $ K, and for 1,2-dichloroethane $\hbox {H}_{2}$ ClC– $\hbox {CH}_{2}{\hbox {Cl}}$ the discord achieves the largest value at $T=0.517~\upmu $ K. In both cases, the discord equals $Q\approx 0.083$ bit/dimer what is $8.3\,\%$ of its upper limit in two-qubit systems. We estimate also that for gypsum at room temperature $Q\sim 10^{-18}$ bit/dimer, and for 1,2-dichloroethane at $T=90$ K the discord is $Q\sim 10^{-17}$ bit per a dimer. 相似文献
20.
There is no doubt that the enormous amounts of information on the WWW are influencing how we work, live, learn and think. However, information on the WWW is in general too chaotic, not reliable enough and specific material often too difficult to locate that it cannot be considered a serious digital library. In this paper we concentrate on the question how we can retrieve reliable information from the Web, a task that is fraught with problems, but essential if the WWW is supposed to be used as serious digital library. It turns out that the use of search engines has many dangers. We will point out some of the possible ways how those dangers can be reduced and how dangerous traps can be avoided. Another approach to find useful information on the Web is to use “classical” resources of information like specialized dictionaries, lexica or encyclopaedias in electronic form, such as the Britannica. Although it seemed for a while that such resources might more or less disappear from the Web due to attempts such as Wikipedia, some to the classical encyclopaedias and specialized offerings have picked up steam again and should not be ignored. They do sometimes suffer from what we will call the “wishy-washy” syndrome explained in this paper. It is interesting to note that Wikipedia which is also larger than all other encyclopaedias (at least the English version) is less afflicted by this syndrome, yet has some other serious drawbacks. We discuss how those could be avoided and present a system that is halfway between prototype and production system that does take care of many of the aforementioned problems and hence may be a model for further undertakings in turning (part of) the Web into a useable digital library. 相似文献
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