Democratization in a passive dendritic tree: an analytical investigation

One way to achieve amplification of distal synaptic inputs on a dendritic tree is to scale the amplitude and/or duration of the synaptic conductance with its distance from the soma. This is an example of what is often referred to as “dendritic democracy”. Although well studied experimentally, to date this phenomenon has not been thoroughly explored from a mathematical perspective. In this paper we adopt a passive model of a dendritic tree with distributed excitatory synaptic conductances and analyze a number of key measures of democracy. In particular, via moment methods we derive laws for the transport, from synapse to soma, of strength, characteristic time, and dispersion. These laws lead immediately to synaptic scalings that overcome attenuation with distance. We follow this with a Neumann approximation of Green’s representation that readily produces the synaptic scaling that democratizes the peak somatic voltage response. Results are obtained for both idealized geometries and for the more realistic geometry of a rat CA1 pyramidal cell. For each measure of democratization we produce and contrast the synaptic scaling associated with treating the synapse as either a conductance change or a current injection. We find that our respective scalings agree up to a critical distance from the soma and we reveal how this critical distance decreases with decreasing branch radius.

Fluidic flow delay by ionogel passive pumps in microfluidic paper-based analytical devices

[EN] A new concept for fluid flow manipulation in microfluidic paper-based analytical devices (m-PADs) is presented by introducing ionogel materials as passive pumps. m-PADs were fabricated using a new doubleside contact stamping process and ionogels were precisely photopolymerised at the inlet of the m-PADs.The ionogels remain mainly on the surface of the paper and get absorbed in the superficial paper-fibers allowing for the liquid to flow from the ionogel into the paper easily. As a proof of concept the fluid flowand mixing behaviour of two different ionogels mPADs were compared with the non-treated mPADs.It was demonstrated that both ionogels highly affect the fluid flow by delaying the flow due to their different physical and chemical properties and water holding capacities.

Active versus passive management : the case of BOVESPA

Mestrado em Finanças

Evaluation of the Effect of Passive Smoking on Lactoferrin and AST on 12 - 15 Years Old Children and Adolescents

Background: Passive smokers are involuntarily exposed to cigarette or tobacco smoke and as known, inhalation of environmental tobacco smoke is a serious threat. There is little information about the effect of passive smoking on salivary markers and periodontal indices. Objectives: This study investigated the effect of passive smoking on lactoferrin and AST in 12 - 15 years old children and adolescents. Patients and Methods: This case-control analytic correlation type study with no-convenience random sampling method was performed on 160 children aged 12 - 15 who had smokers in their families. The eligible children were divided into two equal groups; 80 cot+ children as case group and 80 cot– children as control group, matched according to age, sex and plaque index. Plaque index was obtained from all subjects. 2 cc unstimulated salivary samples were collected by spitting method. The collected specimens were tested by lactoferrin and AST kits in biochemistry were measured on the day of sampling laboratory. Gingival index Loe and Silness (GI) and Probing Pocket Depth (PPD). Results: Mean and Standard Deviation of PPD and GI was 2.01 ± 0.077 and 1.53 ± 0.055 in experimental group and 1.93 ± 0.073 and 1.49 ± 0.046 in control group respectively (P < 0.001). The Mean and Standard Deviation parameters of lactoferrin and AST, in the experimental group was 38.66 ± 25.15 and 13.45 ± 6.33 and in the control group 10.18 ± 6.82 and 6.53 ± 2.65 group, respectively (P < 0.001). Conclusions: Passive smoking can be effective on inflammatory process of periodontal and salivary biomarkers related to inflammation. Lactoferrin was 11 - 104 in case group and 0.5 - 38 in control group. Aspartat aminotransferase in case group was 2.64 - 30.43 and in control group it was 2.16 - 12.02.

Erratum: selection of suitable passive cooling strategy for a subtropical climate

In the original version of this article (Ahmed et al. 2014), the authors noted that the author list was published with errors. The correct author list can be found in this erratum. The publisher would like to apologise to the authors for this error.

Salt promotes passive overconsumption of dietary fat in humans

BACKGROUND: Excess fat consumption has been linked to the development of obesity. Fat and salt are a common and appetitive combination in food; however, the effect of either on food intake is unclear. Fat taste sensitivity has been negatively associated with dietary fat intake, but how fat taste sensitivity influences the intake of fat within a meal has, to our knowledge, not yet been investigated.

OBJECTIVES: Our objectives were, first, to investigate the effects of both fat and salt on ad libitum food intake and, second, to investigate the effects of fat taste sensitivity on satiation responses to fat and whether this was affected by salt.

METHODS: Forty-eight healthy adults [16 men and 32 women, aged 18-54 y, body mass index (kg/m(2)): 17.8-34.4] were recruited and their fat taste sensitivity was measured by determination of the detection threshold of oleic acid (18:1n-6). In a randomized 2 × 2 crossover design, participants attended 4 lunchtime sessions after a standardized breakfast. Meals consisted of elbow macaroni (56%) with sauce (44%); sauces were manipulated to be1) low-fat (0.02% fat, wt:wt)/low-salt (0.06% NaCl, wt:wt),2) low-fat/high-salt (0.5% NaCl, wt:wt),3) high-fat (34% fat, wt:/wt)/low-salt, or4) high-fat/high-salt. Ad libitum intake (primary outcome) and eating rate, pleasantness, and subjective ratings of hunger and fullness (secondary outcomes) were measured.

RESULTS: Salt increased food and energy intakes by 11%, independent of fat concentration (P= 0.022). There was no effect of fat on food intake (P= 0.6), but high-fat meals increased energy intake by 60% (P< 0.001). A sex × fat interaction was found (P= 0.006), with women consuming 15% less by weight of the high-fat meals than the low-fat meals. Fat taste sensitivity was negatively associated with the intake of high-fat meals but only in the presence of low salt (fat taste × salt interaction on delta intake of high-fat - low-fat meals;P= 0.012).

CONCLUSIONS: The results suggest that salt promotes passive overconsumption of energy in adults and that salt may override fat-mediated satiation in individuals who are sensitive to the taste of fat.

Development of a 1-D Catalyzed Diesel Particulate Filter Model for Simulation of the Performance and the Oxidation of Particulate Matter and Nitrogen Oxides Using Passive Oxidation and Active Regeneration Engine Experimental Data

Back-pressure on a diesel engine equipped with an aftertreatment system is a function of the pressure drop across the individual components of the aftertreatment system, typically, a diesel oxidation catalyst (DOC), catalyzed particulate filter (CPF) and selective catalytic reduction (SCR) catalyst. Pressure drop across the CPF is a function of the mass flow rate and the temperature of the exhaust flowing through it as well as the mass of particulate matter (PM) retained in the substrate wall and the cake layer that forms on the substrate wall. Therefore, in order to control the back-pressure on the engine at low levels and to minimize the fuel consumption, it is important to control the PM mass retained in the CPF. Chemical reactions involving the oxidation of PM under passive oxidation and active regeneration conditions can be utilized with computer numerical models in the engine control unit (ECU) to control the pressure drop across the CPF. Hence, understanding and predicting the filtration and oxidation of PM in the CPF and the effect of these processes on the pressure drop across the CPF are necessary for developing control strategies for the aftertreatment system to reduce back-pressure on the engine and in turn fuel consumption particularly from active regeneration. Numerical modeling of CPF's has been proven to reduce development time and the cost of aftertreatment systems used in production as well as to facilitate understanding of the internal processes occurring during different operating conditions that the particulate filter is subjected to. A numerical model of the CPF was developed in this research work which was calibrated to data from passive oxidation and active regeneration experiments in order to determine the kinetic parameters for oxidation of PM and nitrogen oxides along with the model filtration parameters. The research results include the comparison between the model and the experimental data for pressure drop, PM mass retained, filtration efficiencies, CPF outlet gas temperatures and species (NO2) concentrations out of the CPF. Comparisons of PM oxidation reaction rates obtained from the model calibration to the data from the experiments for ULSD, 10 and 20% biodiesel-blended fuels are presented.

DESIGN AND APPLICATION OF WIRELESS PASSIVE MAGNETOELASTIC RESONANCE AND MAGNETOHARMONIC FORCE SENSORS

The objective of the work described in this dissertation is the development of new wireless passive force monitoring platforms for applications in the medical field, specifically monitoring lower limb prosthetics. The developed sensors consist of stress sensitive, magnetically soft amorphous metallic glass materials. The first technology is based on magnetoelastic resonance. Specifically, when exposed to an AC excitation field along with a constant DC bias field, the magnetoelastic material mechanically vibrates, and may reaches resonance if the field frequency matches the mechanical resonant frequency of the material. The presented work illustrates that an applied loading pins portions of the strip, effectively decreasing the strip length, which results in an increase in the frequency of the resonance. The developed technology is deployed in a prototype lower limb prosthetic sleeve for monitoring forces experienced by the distal end of the residuum. This work also reports on the development of a magnetoharmonic force sensor comprised of the same material. According to the Villari effect, an applied loading to the material results in a change in the permeability of the magnetic sensor which is visualized as an increase in the higher-order harmonic fields of the material. Specifically, by applying a constant low frequency AC field and sweeping the applied DC biasing field, the higher-order harmonic components of the magnetic response can be visualized. This sensor technology was also instrumented onto a lower limb prosthetic for proof of deployment; however, the magnetoharmonic sensor illustrated complications with sensor positioning and a necessity to tailor the interface mechanics between the sensing material and the surface being monitored. The novelty of these two technologies is in their wireless passive nature which allows for long term monitoring over the life time of a given device. Additionally, the developed technologies are low cost. Recommendations for future works include improving the system for real-time monitoring, useful for data collection outside of a clinical setting.

From Passive to Active Community Conservation: A Study of Forest Governance in a Region of the Sierra Norte of Oaxaca, Mexico

This thesis investigates how seven communities in a subregion of the Sierra Norte of Oaxaca are conserving high forest cover in the absence of national protected areas. To conduct this study I relied on archival research and the review of community documents, focus group interviews and land use transects to explore historical and current land use. I found that communities have conserved 88.34% of the subregion as forest cover, or 58,596 hectares out of a total territory of 66,264 hectares. Analysis suggests that the communities have undergone a historical transition from more passive conservation to more active, conscious conservation particularly in the last decade. This thesis further contends that communities deserve additional financial compensation for this active conservation of globally important forests for biodiversity conservation and that exercises in systematic conservation planning ignore the reality that existing biodiversity conservation in the subregion is associated with community ownership.

Predicting room occupancy with a single passive infrared (PIR) sensor through behavior extraction

Passive infrared sensors have widespread use in many applications, including motion detectors for alarms, lighting systems and hand dryers. Combinations of multiple PIR sensors have also been used to count the number of humans passing through doorways. In this paper, we demonstrate the potential of the PIR sensor as a tool for occupancy estimation inside of a monitored environment. Our approach shows how flexible nonparametric machine learning algorithms extract useful information about the occupancy from a single PIR sensor. The approach allows us to understand and make use of the motion patterns generated by people within the monitored environment. The proposed counting system uses information about those patterns to provide an accurate estimate of room occupancy which can be updated every 30 seconds. The system was successfully tested on data from more than 50 real office meetings consisting of at most 14 room occupants.

Experiences in Passively Detecting Session Hijacking Attacks in IEEE 802.11 Networks

Current IEEE 802.11 wireless networks are vulnerable to session hijacking attacks as the existing standards fail to address the lack of authentication of management frames and network card addresses, and rely on loosely coupled state machines. Even the new WLAN security standard - IEEE 802.11i does not address these issues. In our previous work, we proposed two new techniques for improving detection of session hijacking attacks that are passive, computationally inexpensive, reliable, and have minimal impact on network performance. These techniques utilise unspoofable characteristics from the MAC protocol and the physical layer to enhance confidence in the intrusion detection process. This paper extends our earlier work and explores usability, robustness and accuracy of these intrusion detection techniques by applying them to eight distinct test scenarios. A correlation engine has also been introduced to maintain the false positives and false negatives at a manageable level. We also explore the process of selecting optimum thresholds for both detection techniques. For the purposes of our experiments, Snort-Wireless open source wireless intrusion detection system was extended to implement these new techniques and the correlation engine. Absence of any false negatives and low number of false positives in all eight test scenarios successfully demonstrated the effectiveness of the correlation engine and the accuracy of the detection techniques.

Medeleven

Medeleven was a practice-based research work that challenged conventional notions of how audiences ‘experience’ contemporary dance. It resulted in a 40 minute ‘experiential’ performance that inverted the traditional ‘passive’ presentation paradigm by situating the audience centrally within the creative process. The ‘traditional presentation paradigm’ was inverted in numerous ways including: asking the audience onstage with the performers, placing swings onstage for the audience to play on during the performance and guiding the audience through backstage corridors before entering onstage – all of which added elements of physicality, agency and liminality to the performance not usually available to audience members of contemporary dance. Five dancers moved throughout the space allowing the audience to choose where and how they engaged with this work and the swings were utilised both as a performance space and for audience seating. In addition to these spatial variations, the quadraphonic soundscore created distinct ‘environments’ throughout the stage space that varied individual experience possibilities. By positing performance as an experiential phenomenon, the pivotal objective of this work was to create a live-art experience that extended its performativity to include audience members as active meaning-makers, challenging both their role within this paradigm and their expectations of contemporary dance. The work produced strong responses from the audience with surveys indicating the presentation format, as well as the construction of the work, changed audience experience and ability to connect with the dance work. The research suggested that, in addition to existing research on dance audiences, barriers to engagement with contemporary dance may include how the art is constructed and where the audience is positioned within that creative framework. The research builds upon artistic practices being undertaken throughout the world that challenge the notion of existing ‘passive’ performance paradigms via creative ‘engagement’ with audience.

Improving daylighting performance of mirrored light pipes

This paper assesses and compares the performances of two daylight collection strategies, one passive and one active, for large-scale mirrored light pipes (MLP) illuminating deep plan buildings. Both strategies use laser cut panels (LCP) as the main component of the collection system. The passive system comprises LCPs in pyramid form, whereas the active system uses a tiled LCP on a simple rotation mechanism that rotates 360° in 24 hours. Performance is assessed using scale model testing under sunny sky conditions and mathematical modelling. Results show average illuminance levels for the pyramid LCP ranging from 50 to 250 lux and 150 to 200 lux for the rotating LCPs. Both systems improve the performance of a MLP. The pyramid LCP increases the performance of a MLP by 2.5 times and the rotating LCP by 5 times, when compared to an open pipe particularly for low sun elevation angles.