Scanning Behavior Research Articles

Transcriptional Regulation in Ebola Virus: Effects of Gene Border Structure and Regulatory Elements on Gene Expression and Polymerase Scanning Behavior.

The highly pathogenic Ebola virus (EBOV) has a nonsegmented negative-strand (NNS) RNA genome containing seven genes. The viral genes either are separated by intergenic regions (IRs) of variable length or overlap. The structure of the EBOV gene overlaps is conserved throughout all filovirus genomes and is distinct from that of the overlaps found in other NNS RNA viruses. Here, we analyzed how diverse gene borders and noncoding regions surrounding the gene borders influence transcript levels and govern polymerase behavior during viral transcription. Transcription of overlapping genes in EBOV bicistronic minigenomes followed the stop-start mechanism, similar to that followed by IR-containing gene borders. When the gene overlaps were extended, the EBOV polymerase was able to scan the template in an upstream direction. This polymerase feature seems to be generally conserved among NNS RNA virus polymerases. Analysis of IR-containing gene borders showed that the IR sequence plays only a minor role in transcription regulation. Changes in IR length were generally well tolerated, but specific IR lengths led to a strong decrease in downstream gene expression. Correlation analysis revealed that these effects were largely independent of the surrounding gene borders. Each EBOV gene contains exceptionally long untranslated regions (UTRs) flanking the open reading frame. Our data suggest that the UTRs adjacent to the gene borders are the main regulators of transcript levels. A highly complex interplay between the different cis-acting elements to modulate transcription was revealed for specific combinations of IRs and UTRs, emphasizing the importance of the noncoding regions in EBOV gene expression control. Our data extend those from previous analyses investigating the implication of noncoding regions at the EBOV gene borders for gene expression control. We show that EBOV transcription is regulated in a highly complex yet not easily predictable manner by a set of interacting cis-active elements. These findings are important not only for the design of recombinant filoviruses but also for the design of other replicon systems widely used as surrogate systems to study the filovirus replication cycle under low biosafety levels. Insights into the complex regulation of EBOV transcription conveyed by noncoding sequences will also help to interpret the importance of mutations that have been detected within these regions, including in isolates of the current outbreak.

NxControl instead of pitch-and-power

A command system for manual control of the longitudinal load factor in flight path direction of an aircraft is designed that completes existing flight control command systems (e.g. with sidesticks that command normal load factor). The system is called nxControl. It aims to assist pilots during manual flight by reducing the workload for monitoring flight parameters as well as for controlling thrust and airbrakes. Important for the nxControl concept is the direct flight mechanical relation between longitudinal load factor and changes of the total aircraft energy. This paper presents the system concept and a prototype realization. The nxControl system consists of the control law that combines the actuation commands for engines and airbrakes, a new input device for the longitudinal load factor command and augmented display elements informing pilots about aircraft energy states to assure situation awareness. In order to investigate the feasibility of the concept as well as to evaluate consequences on human performance, a flight simulator study with airline pilots was conducted. The nxControl prototype was used by the pilots as expected. Changes in instrument scanning behaviour and thrust lever usage confirmed this. After just a short familiarization and practice, the pilots were able to perform standard flight tasks with nxControl without exceeding given tolerance limits. So, the results provide first evidence for the feasibility of the concept.

NxControl instead of pitch-and-power

A command system for manual control of the longitudinal load factor in flight path direction of an aircraft is designed that completes existing flight control command systems (e.g. with sidesticks that command normal load factor). The system is called nxControl. It aims to assist pilots during manual flight by reducing the workload for monitoring flight parameters as well as for controlling thrust and airbrakes. Important for the nxControl concept is the direct flight mechanical relation between longitudinal load factor and changes of the total aircraft energy. This paper presents the system concept and a prototype realization. The nxControl system consists of the control law that combines the actuation commands for engines and airbrakes, a new input device for the longitudinal load factor command and augmented display elements informing pilots about aircraft energy states to assure situation awareness. In order to investigate the feasibility of the concept as well as to evaluate consequences on human performance, a flight simulator study with airline pilots was conducted. The nxControl prototype was used by the pilots as expected. Changes in instrument scanning behaviour and thrust lever usage confirmed this. After just a short familiarization and practice, the pilots were able to perform standard flight tasks with nxControl without exceeding given tolerance limits. So, the results provide first evidence for the feasibility of the concept.

Altered morphological dynamics of activated microglia after induction of status epilepticus.

BackgroundMicroglia cells are the resident macrophages of the central nervous system and are considered its first line of defense. In the normal brain, their ramified processes are highly motile, constantly scanning the surrounding brain tissue and rapidly moving towards sites of acute injury or danger signals. These microglial dynamics are thought to be critical for brain homeostasis. Under pathological conditions, microglial cells undergo “activation,” which modifies many of their molecular and morphological properties. Investigations of the effects of activation on motility are limited and have given mixed results. In particular, little is known about how microglial motility is altered in epilepsy, which is characterized by a strong inflammatory reaction and microglial activation.MethodsWe used a mouse model of status epilepticus induced by kainate injections and time-lapse two-photon microscopy to image GFP-labeled microglia in acute hippocampal brain slices. We studied how microglial activation affected the motility of microglial processes, including basal motility, and their responses to local triggering stimuli.ResultsOur study reveals that microglial motility was largely preserved in kainate-treated animals, despite clear signs of microglial activation. In addition, whereas the velocities of microglial processes during basal scanning and towards a laser lesion were unaltered 48 h after status epilepticus, we observed an increase in the size of the territory scanned by single microglial processes during basal motility and an elevated directional velocity towards a pipette containing a purinergic agonist.ConclusionsMicroglial activation differentially impacted the dynamic scanning behavior of microglia in response to specific acute noxious stimuli, which may be an important feature of the adaptive behavior of microglia during pathophysiological conditions.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-015-0421-6) contains supplementary material, which is available to authorized users.

Visual scanning behavior is related to recognition performance for own- and other-age faces.

It is well-established that our recognition ability is enhanced for faces belonging to familiar categories, such as own-race faces and own-age faces. Recent evidence suggests that, for race, the recognition bias is also accompanied by different visual scanning strategies for own- compared to other-race faces. Here, we tested the hypothesis that these differences in visual scanning patterns extend also to the comparison between own and other-age faces and contribute to the own-age recognition advantage. Participants (young adults with limited experience with infants) were tested in an old/new recognition memory task where they encoded and subsequently recognized a series of adult and infant faces while their eye movements were recorded. Consistent with findings on the other-race bias, we found evidence of an own-age bias in recognition which was accompanied by differential scanning patterns, and consequently differential encoding strategies, for own-compared to other-age faces. Gaze patterns for own-age faces involved a more dynamic sampling of the internal features and longer viewing time on the eye region compared to the other regions of the face. This latter strategy was extensively employed during learning (vs. recognition) and was positively correlated to discriminability. These results suggest that deeply encoding the eye region is functional for recognition and that the own-age bias is evident not only in differential recognition performance, but also in the employment of different sampling strategies found to be effective for accurate recognition.

“Of and beyond medical consequences”: Exploring health information scanning and seeking behaviors of Filipino domestic service workers in Hong Kong

ABSTRACTThe increasing trend for women in developing countries to engage in international and temporary labor migration has exposed female migrant workers to health inequities. In this article, we problematize the impact of international and temporary labor migration on the health of Filipino domestic workers in Hong Kong by exploring their general patterns of health information acquisition. Through a series of focus group discussions with Filipino domestic workers in Hong Kong, we found that employers serve as stakeholders in migration health, social networking sites can be a platform for participatory health promotion, and religious beliefs and behaviors can promote favorable health behaviors.

A first insight into the scanning behaviour of the presocial blow fly larvae

AbstractAggregation of necrophagous larvae has several benefits: the sharing of salivary enzymes (exodigestion), temperature regulation, protection from predators and parasites, etc., and is well developed in blow flies (Diptera: Calliphoridae). The present study focuses on the aggregation mechanism used by the necrophagous larvae of Lucilia sericata Meigen, the common green bottle fly. The ability of single larva to detect and follow a signal (trail) created by conspecifics is investigated initially. A circular ring is drawn in a Petri dish where 20 starved larvae have crawled for a period of 30 min. A naïve (test) larva is then placed in the dish and video‐tracked. Naïve larvae are able to detect the boundaries of the larvae‐crawled area and stay preferentially within this conspecific‐marked zone. In a second step, the orientation of larvae by scanning, a dedicated, ground‐signal detection behaviour of dipteran larvae, is analyzed. Four experimental conditions are tested: control, presence of food, conspecifics, and food + conspecifics. When conspecifics have been previously present in a given area, the scanning behaviour by naïve larvae in this area decreases (both in number and frequency of scans). Accordingly, scanning by necrophagous larvae of L. sericata should be considered not only as locomotion behaviour, but also as a potential way to detect signals from conspecifics for the purpose of aggregation. The chemical composition of the attractant(s), the behavioural effects (attraction or retention) and the implication of larval signalling in the aggregation process are new fields to explore.

Evaluating the novel-environment test for measurement of exploration by bird species

Novel-environment tests are the most widespread experimental technique for characterizing exploration, yet detailed evaluation of their performance among species is lacking. We compared the test for eight bird species by combining three well-known metrics of behavior: movement frequency, proportion of features visited, and scanning. In both overall and species-level analysis of our multi-group principal component analysis, all three metrics loaded strongly and similarly on one principal component, explaining comparable ranges of variation. We conclude that novel-environment tests are a robust means of quantifying exploration and that scanning behavior may be an important but under-used metric for exploration behavior.

Acoustic shadows help gleaning bats find prey, but may be defeated by prey acoustic camouflage on rough surfaces.

Perceptual abilities of animals, like echolocating bats, are difficult to study because they challenge our understanding of non-visual senses. We used novel acoustic tomography to convert echoes into visual representations and compare these cues to traditional echo measurements. We provide a new hypothesis for the echo-acoustic basis of prey detection on surfaces. We propose that bats perceive a change in depth profile and an 'acoustic shadow' cast by prey. The shadow is more salient than prey echoes and particularly strong on smooth surfaces. This may explain why bats look for prey on flat surfaces like leaves using scanning behaviour. We propose that rather than forming search images for prey, whose characteristics are unpredictable, predators may look for disruptions to the resting surface (acoustic shadows). The fact that the acoustic shadow is much fainter on rougher resting surfaces provides the first empirical evidence for 'acoustic camouflage' as an anti-predator defence mechanism.

Using Experts' Eye Movements to Influence Scanning Behaviour in Novice Drivers

In many areas, experts often exhibit specialised eye movement behaviour which allows for more efficient task execution than novices. In some areas (e.g. Radiology), showing this pattern of eye movement behaviour to novices can help cue overt visual attention to more relevant areas; which allows for more efficient task completion. We present a study which investigated the effects of eye movement cueing in a dynamic task - that of driving. The aim was to investigate whether a more efficient visual search pattern (e.g. increased scanning of the road, increased use of mirrors) could be induced in novice drivers if they are shown eye movements of expert drivers, when driving in a simulated environment. One group of participants (eye movement condition) were asked to drive a set of courses in a driving simulator programme whilst their eye movements were tracked. After one week, this group was shown two five minute videos of an expert's drive with the corresponding eye movements overlaid. Participants were then asked to drive the three courses again whilst their eye movements were tracked. Another group of participants (control) were asked to complete similar drives (one week a part also) but were not shown eye movements. After the second driving session, those in the eye movement condition exhibited increased horizontal scanning of the road, larger saccade sizes and showed an increased use of their mirrors as measured by total dwell time and total fixation counts. The control group showed no such improvement in visual strategies. These beneficial eye movement patterns were retained after a six month follow-up. The results show that eye movement cueing can be used to train more efficient search strategies in a dynamic task such as driving. The current results highlight a possible training intervention which could be introduced to educate early-stage drivers. Meeting abstract presented at VSS 2015. Language: en

A Hybrid Swarm Algorithm for optimizing glaucoma diagnosis

Glaucoma is among the most common causes of permanent blindness in human. Because the initial symptoms are not evident, mass screening would assist early diagnosis in the vast population. Such mass screening requires an automated diagnosis technique. Our proposed automation consists of pre-processing, optimal wavelet transformation, feature extraction, and classification modules. The hyper analytic wavelet transformation (HWT) based statistical features are extracted from fundus images. Because HWT preserves phase information, it is appropriate for feature extraction. The features are then classified by a Support Vector Machine (SVM) with a radial basis function (RBF) kernel. The filter coefficients of the wavelet transformation process and the SVM-RB width parameter are simultaneously tailored to best-fit the diagnosis by the hybrid Particle Swarm algorithm. To overcome premature convergence, a Group Search Optimizer (GSO) random searching (ranging) and area scanning behavior (around the optima) are embedded within the Particle Swarm Optimization (PSO) framework. We also embed a novel potential-area scanning as a preventive mechanism against premature convergence, rather than diagnosis and cure. This embedding does not compromise the generality and utility of PSO. In two 10-fold cross-validated test runs, the diagnostic accuracy of the proposed hybrid PSO exceeded that of conventional PSO. Furthermore, the hybrid PSO maintained the ability to explore even at later iterations, ensuring maturity in fitness.

Environmental scanning in business organisations

Purpose– This study aims to analyse the environmental scanning and information sources used by Jordanian firms. Furthermore, the relationship between environmental scanning and organisational characteristics (firm size and industry type), as well as organisational performance, is explored.Design/methodology/approach– The empirical research was coordinated via a survey of 190 Jordanian publicly quoted firms. The results of the survey provided a rich source of data in relation to a variety of practices associated with environmental scanning in these firms.Findings– The findings of this study show that scanning focus was higher for the general environmental sectors than the task environmental sectors. The results also demonstrate that these firms rely more on internal sources of information. Larger firms have more scanning activities, while smaller firms tend to focus on different sources of information. Additionally, some differences in the industry sector in terms of scanning behaviour were identified. This study also supports the literature regarding the positive relationship between environment scanning and organisational performance by providing new empirical evidence from the context of Middle East countries.Originality/value– This paper provides empirical evidence on the nature and the practice of environmental scanning and its value for organisational performance in business firms in a Middle East context. From a theoretical perspective, this study engages in the “convergence versus divergence” debate regarding managers’ scanning behaviour around the world.

Homeostatic regulatory T cell trafficking in peripheral lymph nodes (LYM2P.731)

Abstract Regulatory T cells (Tregs) express the canonical marker Foxp3 and are critical for suppressing the immune response in homeostatic and inflammatory conditions. As widely studied as CD4+Foxp3+ Tregs are in mice, their physiologic trafficking and scanning behavior of antigen-presenting cells in secondary lymphoid organs (SLOs) have yet to be quantitatively analyzed. Our laboratory has previously described the dynamics of naïve T cell trafficking through SLOs and scanning of dendritic cells, revealing that CD4+ T cells and CD8+ T cells have distinct dynamic behaviors in the lymph node (LN). On average, CD4+ T cells spend less time scanning for self-peptide/MHC (self-pMHC), dwell shorter in LNs, and egress faster compared to CD8+ T cells. In this study, we use flow cytometry and 2-photon laser scanning microscopy to quantitate the trafficking kinetics and surveillance strategy of naïve Tregs in C57BL/6 mice LNs and to compare their behavior to conventional T cells. Our data reveal differences in naïve Treg trafficking in mesenteric versus other peripheral LNs. We also show that self-pMHC recognition regulates the scanning behavior and localization of Tregs in peripheral LNs. In addition, we describe a novel imaging platform for high-resolution intravital microscopy of T cell behavior within mesenteric LNs. These results add to mounting evidence that self-pMHC interactions dynamically control physiologic Treg retainment and contact-dependent suppressive function in peripheral LNs.

Visualizing and Modeling the Scanning Behavior of the Conficker Botnet in the Presence of User and Network Activity

Translating behavioral information learned from analysis of a botnet’s software in controlled environments, to a model of how the botnet behaves in the wild is complicated by the fact that controlled environments do not account for a wide variety of user behavior, and that machines are not associated one-to-one with IP addresses. This paper presents a case study using published reports and pertinent visualizations to develop and evaluate a single-machine model of scanning behavior of the Conficker-C botnet, with a goal of understanding the global population of infected machines in light of user activity and IP address allocation.

A study on the natural history of scanning behaviour in patients with visual field defects after stroke

BackgroundA visual field defect (VFD) is a common consequence of stroke with a detrimental effect upon the survivors’ functional ability and quality of life. The identification of effective treatments for VFD is a key priority relating to life post-stroke. Understanding the natural evolution of scanning compensation over time may have important ramifications for the development of efficacious therapies.The study aims to unravel the natural history of visual scanning behaviour in patients with VFD. The assessment of scanning patterns in the acute to chronic stages of stroke will reveal who does and does not learn to compensate for vision loss.Methods/DesignEye-tracking glasses are used to delineate eye movements in a cohort of 100 stroke patients immediately after stroke, and additionally at 6 and 12 months post-stroke. The longitudinal study will assess eye movements in static (sitting) and dynamic (walking) conditions.The primary outcome constitutes the change of lateral eye movements from the acute to chronic stages of stroke. Secondary outcomes include changes of lateral eye movements over time as a function of subgroup characteristics, such as side of VFD, stroke location, stroke severity and cognitive functioning.DiscussionThe longitudinal comparison of patients who do and do not learn compensatory scanning techniques may reveal important prognostic markers of natural recovery. Importantly, it may also help to determine the most effective treatment window for visual rehabilitation.

A Network Behavior-Based Botnet Detection Mechanism Using PSO and K-means

In today's world, Botnet has become one of the greatest threats to network security. Network attackers, or Botmasters, use Botnet to launch the Distributed Denial of Service (DDoS) to paralyze large-scale websites or steal confidential data from infected computers. They also employ “phishing” attacks to steal sensitive information (such as users’ accounts and passwords), send bulk email advertising, and/or conduct click fraud. Even though detection technology has been much improved and some solutions to Internet security have been proposed and improved, the threat of Botnet still exists. Most of the past studies dealing with this issue used either packet contents or traffic flow characteristics to identify the invasion of Botnet. However, there still exist many problems in the areas of packet encryption and data privacy, simply because Botnet can easily change the packet contents and flow characteristics to circumvent the Intrusion Detection System (IDS). This study combines Particle Swarm Optimization (PSO) and K-means algorithms to provide a solution to remedy those problems and develop, step by step, a mechanism for Botnet detection. First, three important network behaviors are identified: long active communication behavior (ActBehavior), connection failure behavior (FailBehavior), and network scanning behavior (ScanBehavior). These behaviors are defined according to the relevant prior studies and used to analyze the communication activities among the infected computers. Second, the features of network behaviors are extracted from the flow traces in the network layer and transport layer of the network equipment. Third, PSO and K-means techniques are used to uncover the host members of Botnet in the organizational network. This study mainly utilizes the flow traces of a campus network as an experiment. The experimental findings show that this proposed approach can be employed to detect the suspicious Botnet members earlier than the detection application systems. In addition, this proposed approach is easy to implement and can be further used and extended in the campus dormitory network, home networks, and the mobile 3G network.

Analysis of a “/0” Stealth Scan From a Botnet

Botnets are the most common vehicle of cyber-criminal activity. They are used for spamming, phishing, denial-of-service attacks, brute-force cracking, stealing private information, and cyber warfare. Botnets carry out network scans for several reasons, including searching for vulnerable machines to infect and recruit into the botnet, probing networks for enumeration or penetration, etc. We present the measurement and analysis of a horizontal scan of the entire IPv4 address space conducted by the Sality botnet in February 2011. This 12-day scan originated from approximately 3 million distinct IP addresses and used a heavily coordinated and unusually covert scanning strategy to try to discover and compromise VoIP-related (SIP server) infrastructure. We observed this event through the UCSD Network Telescope, a /8 darknet continuously receiving large amounts of unsolicited traffic, and we correlate this traffic data with other public sources of data to validate our inferences. Sality is one of the largest botnets ever identified by researchers. Its behavior represents ominous advances in the evolution of modern malware: the use of more sophisticated stealth scanning strategies by millions of coordinated bots, targeting critical voice communications infrastructure. This paper offers a detailed dissection of the botnet's scanning behavior, including general methods to correlate, visualize, and extrapolate botnet behavior across the global Internet.

Where do novice and experienced drivers direct their attention on approach to urban rail level crossings?

Crashes at rail level crossings (RLXs) remain a persistent but ill-defined safety issue. In urban areas, RLXs are typically located in areas of high workload and visual clutter, such as busy shopping strips. Despite this, the impact of such environments on driver behaviour and compliance with RLX controls is not well understood. This study sought to examine where drivers direct their attention on approach to urban RLXs located in busy shopping strip areas, and whether this differs between novice and experienced drivers. Participants drove an instrumented vehicle around a pre-defined urban route containing several active (flashing light with boom barriers) RLXs. Drivers’ visual scanning behaviour and cognitive processes were examined on approach to RLXs. The results suggest that RLXs were not a key focus of drivers’ attention. Further, rather than actively scanning, participants were over-reliant on RLX warning signals and the behaviour of surrounding vehicles to alert them to the presence of both trains and RLXs. This study provides important insights into drivers’ visual and cognitive behaviour on approach to urban RLXs located in areas of high visual demand.

Improving magnetic resonance imaging (MRI) examinations: Development and evaluation of an intervention to reduce movement in scanners and facilitate scan completion.

The movement of patients in magnetic resonance imaging (MRI) scanners results in motion artefacts which impair image quality. Non-completion of scans leads to delay in diagnosis and increased costs. This study aimed to develop and evaluate an intervention to enable patients to stay still in MRI scanners (reducing motion artefacts) and to enhance scan completion. Successful scan outcome was deemed to be completing the scan with no motion artefacts. Previous research indicated self-efficacy to predict successful scan outcome, and interviews with patients identified a need for procedural and sensory information to facilitate successful scan behaviour. A DVD intervention was developed which targeted self-efficacy and included procedural and sensory information. It was successfully piloted with 10 patients and then evaluated in a randomized controlled trial compared with the standard hospital information leaflet (intervention group N = 41; control group N = 42). The clinic radiographer, who was blind to group allocation, rated MRI scans for motion artefact and recorded whether the participant completed the scan; participants completed MRI self-efficacy and anxiety measures. Only one participant reported not finding the DVD useful. Thirty-five participants in the intervention group and 23 in the control group completed scans and had no motion artefacts, χ(2) (1, 83) = 7.84, p < .001 (relative risk of an unsatisfactory outcome in the control group/intervention group = 3.09). The intervention effect was mediated by self-efficacy. The DVD intervention was efficacious and warrants further research to examine generalizability.

Visual Scanning in an Air Traffic Control Tower – A Simulation Study

Air traffic controllers at an airport tower ensure for safe and efficient movements of aircraft at the airport and its vicinity. Their decisions always depend on the current situation. To assess the relevant situational aspects information is mostly acquired visually. During take-off and landing in particular a sufficient picture of the situation is crucial to safe decision making. The acquisition process can be modelled using the SEEV model [1] taking into account the importance of an area of interest. Especially in complex high-traffic situations more areas are considered to be important. It is assumed that controllers also scan more crucial areas in complex than in simple situations. Therefore an eye tracking study was conducted in a high fidelity tower simulator. Six air traffic controllers handled IFR traffic at a local airport with simple as well as more complex situations. Their scanning behavior while giving take-off- and landing-clearances was assessed by a state-of-the-art eye tracking system. Results show similarities among participants and situations regarding visual movements while delivering clearances. Slightly more scans were made in complex than in simple situations. The attended areas indicate highly trained behavior of the controllers. The data were merged to provide reference values to be compared to real time eye tracking. The applicability of such a system as a tool to detect inattentiveness in air traffic control is discussed.