756 research outputs found
Staying on Course: Three Year Results of the National Guard Youth ChalleNGe Evaluation
Evaluates the effectiveness of a quasi-military residential and mentoring program that aims to place high school dropouts in employment, education, or military service and improve outcomes including indicators of health, lifestyle, and delinquency
A 3D Smith Chart based on the Riemann Sphere for Active and Passive Microwave Circuits
“© © 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.”This letter proposes a spherical 3-D Smith Chart suitable for representing both active and passive microwave circuits. Using the mathematical concept of the Riemann sphere, the extended reflection coefficient plane is transformed into the surface of the unit sphere. Since the proposed Smith Chart compiles the whole complex plane, all possible loads are included. A simple graphic tool is thus obtained that successfully unifies active and passive circuits. In addition, lossy lines with complex characteristic impedances can also be represented. The letter presents the 3-D Smith Chart, provides its main governing equations, and also enumerates its more important properties. © 2011 IEEE.This work was supported in part by the POSDRU ID 7713 European Project and by the Ministerio de Ciencia e Innovacion, Spanish Government under Research Project TEC2010-21520-C04-01.Muller, AA.; Soto Pacheco, P.; Dascalu, D.; Neculoiu, D.; Boria Esbert, VE. (2011). A 3D Smith Chart based on the Riemann Sphere for Active and Passive Microwave Circuits. IEEE Microwave and Wireless Components Letters. 21(6):286-288. https://doi.org/10.1109/LMWC.2011.2132697S28628821
Processable aqueous dispersions of graphene nanosheets
Graphene sheets offer extraordinary electronic, thermal and mechanical properties and are expected to find a variety of applications. A prerequisite for exploiting most proposed applications for graphene is the availability of processable graphene sheets in large quantities. The direct dispersion of hydrophobic graphite or graphene sheets in water without the assistance of dispersing agents has generally been considered to be an insurmountable challenge. Here we report that chemically converted graphene sheets obtained from graphite can readily form stable aqueous colloids through electrostatic stabilization. This discovery has enabled us to develop a facile approach to large-scale production of aqueous graphene dispersions without the need for polymeric or surfactant stabilizers. Our findings make it possible to process graphene materials using low-cost solution processing techniques, opening up enormous opportunities to use this unique carbon nanostructure for many technological applications
Visions, Values, and Videos: Revisiting Envisionings in Service of UbiComp Design for the Home
UbiComp has been envisioned to bring about a future dominated by calm
computing technologies making our everyday lives ever more convenient. Yet the
same vision has also attracted criticism for encouraging a solitary and passive
lifestyle. The aim of this paper is to explore and elaborate these tensions
further by examining the human values surrounding future domestic UbiComp
solutions. Drawing on envisioning and contravisioning, we probe members of the
public (N=28) through the presentation and focus group discussion of two
contrasting animated video scenarios, where one is inspired by "calm" and the
other by "engaging" visions of future UbiComp technology. By analysing the
reasoning of our participants, we identify and elaborate a number of relevant
values involved in balancing the two perspectives. In conclusion, we articulate
practically applicable takeaways in the form of a set of key design questions
and challenges.Comment: DIS'20, July 6-10, 2020, Eindhoven, Netherland
Neuromorphic Hardware In The Loop: Training a Deep Spiking Network on the BrainScaleS Wafer-Scale System
Emulating spiking neural networks on analog neuromorphic hardware offers
several advantages over simulating them on conventional computers, particularly
in terms of speed and energy consumption. However, this usually comes at the
cost of reduced control over the dynamics of the emulated networks. In this
paper, we demonstrate how iterative training of a hardware-emulated network can
compensate for anomalies induced by the analog substrate. We first convert a
deep neural network trained in software to a spiking network on the BrainScaleS
wafer-scale neuromorphic system, thereby enabling an acceleration factor of 10
000 compared to the biological time domain. This mapping is followed by the
in-the-loop training, where in each training step, the network activity is
first recorded in hardware and then used to compute the parameter updates in
software via backpropagation. An essential finding is that the parameter
updates do not have to be precise, but only need to approximately follow the
correct gradient, which simplifies the computation of updates. Using this
approach, after only several tens of iterations, the spiking network shows an
accuracy close to the ideal software-emulated prototype. The presented
techniques show that deep spiking networks emulated on analog neuromorphic
devices can attain good computational performance despite the inherent
variations of the analog substrate.Comment: 8 pages, 10 figures, submitted to IJCNN 201
Ethnobotanical Knowledge of Men, Women and Children in Rural Niger: A mixedmethods approach
researchEthnobotanical studies often underestimate or misrepresent impacts of age and gender on individual ethnobotanical knowledge. This paper compares two common methodologies, participant observation and key-informant interviews, to examine the variation of ethnobotanical knowledge across age and gender in three communities in rural southwest Niger. We compared lists of plants mentioned in interviews as food, fodder, construction and medicine, to lists compiled from observations of daily activities. Compared to men, women reported more edible plants, different medicinal plants, and less detailed information on construction plants. Interview data indicated ethnobotanical knowledge increased with age. However, in observations youth ate a greater diversity of food plants and identified and ranked fodder species more quickly than adults. This paper supports previous research on age and gender effects on ethnobotanical knowledge and critiques common research methods and assumptions. We advocate for mixed-method approaches to gather more nuanced understandings of ethnobotanical knowledge
Comparative performance of airyscan and structured illumination superresolution microscopy in the study of the surface texture and 3D shape of pollen
The visualization of taxonomically diagnostic features of individual pollen grains can be a challenge for many ecologically and phylogenetically important pollen types. The resolution of traditional optical microscopy is limited by the diffraction of light (250 nm), while high resolution tools such as electron microscopy are limited by laborious preparation and imaging workflows. Airyscan confocal superresolution and structured illumination superresolution (SR-SIM) microscopy are powerful new tools for the study of nanoscale pollen morphology and three-dimensional structure that can overcome these basic limitations. This study demonstrates their utility in capturing morphological details below the diffraction limit of light. Using three distinct pollen morphotypes (Croton hirtus, Dactylis glomerata, and Helianthus sp.) and contrast-enhancing fluorescent staining, we were able to assess the effectiveness of the Airyscan and SR-SIM. We further demonstrate that these new superresolution methods can be easily applied to the study of fossil pollen material
Emergent properties arising from spatial heterogeneity influence fungal community dynamics
Community dynamics are mediated by species interactions, and within communities spatial heterogeneity and intransitive relationships promote coexistence. However, few experimental studies have assessed effects of heterogeneity on the interactions of competing individuals. Wood decay basidiomycete fungi are ideal for studying community structure and dynamics because they are easy to manipulate in laboratory microcosms, and communities resolve themselves rapidly. Most studies have only used simplistic pair-wise interactions in a 2-D plane, but here we investigate a three-species community in an environmentally realistic novel 3-dimensional system. We show how spatial heterogeneity and patch size dynamics are important for coexistence, and how competitive interactions change over different spatial dimensions. Emergent properties arose with increased spatial heterogeneity: the weakest competitor co-occurred with the community when its territory was less fragmented, and interactions became intransitive
One-year outcomes after transcatheter insertion of an interatrial shunt device for the management of heart failure with preserved ejection fraction
Background—Heart failure with preserved ejection fraction has a complex pathophysiology and remains a therapeutic challenge. Elevated left atrial pressure, particularly during exercise, is a key contributor to morbidity and mortality. Preliminary analyses have demonstrated that a novel interatrial septal shunt device that allows shunting to reduce the left atrial pressure provides clinical and hemodynamic benefit at 6 months. Given the chronicity of heart failure with preserved ejection fraction, evidence of longer-term benefit is required.
Methods and Results—Patients (n=64) with left ventricular ejection fraction ≥40%, New York Heart Association class II–IV, elevated pulmonary capillary wedge pressure (≥15 mm Hg at rest or ≥25 mm Hg during supine bicycle exercise) participated in the open-label study of the interatrial septal shunt device. One year after interatrial septal shunt device implantation, there were sustained improvements in New York Heart Association class (P<0.001), quality of life (Minnesota Living with Heart Failure score, P<0.001), and 6-minute walk distance (P<0.01). Echocardiography showed a small, stable reduction in left ventricular end-diastolic volume index (P<0.001), with a concomitant small stable increase in the right ventricular end-diastolic volume index (P<0.001). Invasive hemodynamic studies performed in a subset of patients demonstrated a sustained reduction in the workload corrected exercise pulmonary capillary wedge pressure (P<0.01). Survival at 1 year was 95%, and there was no evidence of device-related complications.
Conclusions—These results provide evidence of safety and sustained clinical benefit in heart failure with preserved ejection fraction patients 1 year after interatrial septal shunt device implantation. Randomized, blinded studies are underway to confirm these observations
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