5,913 research outputs found

    Hospital Networks and the Dispersal of Hospital-Acquired Pathogens by Patient Transfer

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    Hospital-acquired infections (HAI) are often seen as preventable incidents that result from unsafe practices or poor hospital hygiene. This however ignores the fact that transmissibility is not only a property of the causative organisms but also of the hosts who can translocate bacteria when moving between hospitals. In an epidemiological sense, hospitals become connected through the patients they share. We here postulate that the degree of hospital connectedness crucially influences the rates of infections caused by hospital-acquired bacteria. To test this hypothesis, we mapped the movement of patients based on the UK-NHS Hospital Episode Statistics and observed that the proportion of patients admitted to a hospital after a recent episode in another hospital correlates with the hospital-specific incidence rate of MRSA bacteraemia as recorded by mandatory reporting. We observed a positive correlation between hospital connectedness and MRSA bacteraemia incidence rate that is significant for all financial years since 2001 except for 2008–09. All years combined, this correlation is positive and significantly different from zero (partial correlation coefficient r = 0.33 (0.28 to 0.38)). When comparing the referral pattern for English hospitals with referral patterns observed in the Netherlands, we predict that English hospitals more likely see a swifter and more sustained spread of HAIs. Our results indicate that hospitals cannot be viewed as individual units but rather should be viewed as connected elements of larger modular networks. Our findings stress the importance of cooperative effects that will have a bearing on the planning of health care systems, patient management and hospital infection control

    The Photoelectric Effect: Project-based Undergraduate Teaching and Learning Optics through a Modern Physics Experiment Redesign

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    The photoelectric effect is a cornerstone textbook experiment in any Modern Physics or Advanced Laboratory course, designed to verify Einstein’s theory of the photoelectric effect, with the implicit determination of an experimental value for Planck’s constant and the demonstration of the particle nature of light. The standard approach to the experiment is to illuminate the light-sensitive cathode of a vacuum-tube photocell with monochromatic light of known wavelengths; a reversed-voltage is then applied to the photocell and adjusted to bring the photoelectric current to zero. The stopping voltage is then plotted as a function of the inverse wavelength or frequency of the incident light, and Planck\u27s constant is determined from the slope of the graph. Additionally, a value for the work function of the photocathode can be extracted from the intercept. The commercial apparatus for the experiment is available from a number of vendors (PASCO, Leybold) in various forms, degrees of performance and cost. However, designing and assembling a photoelectric effect experiment apparatus can in itself be a valuable experiential project-based undergraduate learning opportunity in Optics involving both fundamental light and optics theory and practical optics and opto-mechanical design aspects. This presentation details a project undertaken in the Applied Physics/Engineering Physics programs at Kettering University involving students in a Modern Physics laboratory course. The first phase of the project, discussed in detail in this paper, was a redesign of an existing photoelectric effect apparatus through an undergraduate student thesis, currently in advanced stages of completion. In a second phase of the project we plan to replicate the newly assembled experimental apparatus up to as many as six identical stations and deploy it in our Modern Physics lab course. Typically, more than 50% of the students in this course are engineering majors who would otherwise not get any significant exposure to problems of optics and optical design. We believe that the modular design of the new apparatus together with a carefully redesigned lab activity will allow us to have our students explore major aspects of optics and optoelectronic design while performing this classic Modern Physics experiment

    Student Reciprocal Peer Teaching as a Method for Active Learning: An Experience in an Electrotechnical Laboratory

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    Active learning is one of the most efficient mechanisms for learning, according to the psychology of learning. When students act as teachers for other students, the communication is more fluent and knowledge is transferred easier than in a traditional classroom. This teaching method is referred to in the literature as reciprocal peer teaching. In this study, the method is applied to laboratory sessions of a higher education institution course, and the students who act as teachers are referred to as ‘‘laboratory monitors.’’ A particular way to select the monitors and its impact in the final marks is proposed. A total of 181 students participated in the experiment, experiences with laboratory monitors are discussed, and methods for motivating and training laboratory monitors and regular students are proposed. The types of laboratory sessions that can be led by classmates are discussed. This work is related to the changes in teaching methods in the Spanish higher education system, prompted by the Bologna Process for the construction of the European Higher Education Are

    A novel energy management strategy for the ternary lithium batteries based on the dynamic equivalent circuit modeling and differential Kalman filtering under time-varying conditions.

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    The dynamic model of the ternary lithium battery is a time-varying nonlinear system due to the polarization and diffusion effects inside the battery in its charge-discharge process. Based on the comprehensive analysis of the energy management methods, the state of charge is estimated by introducing the differential Kalman filtering method combined with the dynamic equivalent circuit model considering the nonlinear temperature coefficient. The model simulates the transient response with high precision which is suitable for its high current and complicated charging and discharging conditions. In order to better reflect the dynamic characteristics of the power ternary lithium battery in the step-type charging and discharging conditions, the polarization circuit of the model is differential and the improved iterate calculation model is obtained. As can be known from the experimental verifications, the maximize state of charge estimation error is only 0.022 under the time-varying complex working conditions and the output voltage is monitored simultaneously with the maximum error of 0.08 V and the average error of 0.04 V. The established model can describe the dynamic battery behavior effectively, which can estimate its state of charge value with considerably high precision, providing an effective energy management strategy for the ternary lithium batteries

    誘導性エネルギー蓄積に基づくパルスパワー発生に関する研究

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    国立大学法人長岡技術科学大

    Towards understanding the role of central processing in release from masking

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    People with normal hearing have the ability to listen to a desired target sound while filtering out unwanted sounds in the background. However, most patients with hearing impairment struggle in noisy environments, a perceptual deficit which current hearing aids and cochlear implants cannot resolve. Even though peripheral dysfunction of the ears undoubtedly contribute to this deficit, surmounting evidence has implicated central processing in the inability to detect sounds in background noise. Therefore, it is essential to better understand the underlying neural mechanisms by which target sounds are dissociated from competing maskers. This research focuses on two phenomena that help suppress background sounds: 1) dip-listening, and 2) directional hearing. When background noise fluctuates slowly over time, both humans and animals can listen in the dips of the noise envelope to detect target sound, a phenomenon referred to as dip-listening. Detection of target sound is facilitated by a central neuronal mechanism called envelope locking suppression. At both positive and negative signal-to-noise ratios (SNRs), the presence of target energy can suppress the strength by which neurons in auditory cortex track background sound, at least in anesthetized animals. However, in humans and animals, most of the perceptual advantage gained by listening in the dips of fluctuating noise emerges when a target is softer than the background sound. This raises the possibility that SNR shapes the reliance on different processing strategies, a hypothesis tested here in awake behaving animals. Neural activity of Mongolian gerbils is measured by chronic implantation of silicon probes in the core auditory cortex. Using appetitive conditioning, gerbils detect target tones in the presence of temporally fluctuating amplitude-modulated background noise, called masker. Using rate- vs. timing-based decoding strategies, analysis of single-unit activity show that both mechanisms can be used for detecting tones at positive SNR. However, only temporal decoding provides an SNR-invariant readout strategy that is viable at both positive and negative SNRs. In addition to dip-listening, spatial cues can facilitate the dissociation of target sounds from background noise. Specifically, an important cue for computing sound direction is the time difference in arrival of acoustic energy reaching each ear, called interaural time difference (ITD). ITDs allow localization of low frequency sounds from left to right inside the listener\u27s head, also called sound lateralization. Models of sound localization commonly assume that sound lateralization from interaural time differences is level invariant. Here, two prevalent theories of sound localization are observed to make opposing predictions. The labelled-line model encodes location through tuned representations of spatial location and predicts that perceived direction is level invariant. In contrast, the hemispheric-difference model encodes location through spike-rate and predicts that perceived direction becomes medially biased at low sound levels. In this research, through behavioral experiments on sound lateralization, the computation of sound location with ITDs is tested. Four groups of normally hearing listeners lateralize sounds based on ITDs as a function of sound intensity, exposure hemisphere, and stimulus history. Stimuli consists of low-frequency band-limited white noise. Statistical analysis, which partial out overall differences between listeners, is inconsistent with the place-coding scheme of sound localization, and supports the hypothesis that human sound localization is instead encoded through a population rate-code

    Modular DC-DC Converters

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    DC-DC converter is one of the mostly used power electronic circuits, and it has applications in various areas ranging from portable devices to aircraft power system. Various topologies of dc-dc converters are suitable for different applications. In high power applications such as the bi-directional dc-dc converter for dual bus system in new generation automobiles, several topologies can be considered as a potential candidate. Regardless of the topology used for this application, the reliability of the converter can be greatly enhanced by introducing redundancy of some degree into the system. Using redundancy, uninterrupted operation of the circuit may be ensured when a fault has occurred. The redundancy feature can be obtained by paralleling multiple converters or using a single modular circuit that can achieve this attribute. Thus, a modular dc-dc converter with redundancy is expected to increase the reliability and reduce the system cost. Recently, the advancement in power electronics research has extended its applications in hybrid electric automobiles. Several key requirements of this application are reliable, robust, and high efficiency operation at low cost. In general, the efficiency and reliability of a power electronic circuit greatly depend on the kind of circuit topology used in any application. This is one of the biggest motivations for the researchers to invent new power electronic circuit topologies that will have significant impact in future automobile industry. This dissertation reviews existing modularity in power electronic circuits, and presents a new modular capacitor clamped dc-dc converter design that has many potential uses in future automotive power system. This converter has multilevel operation, and it is capable of handling bi-directional power. Moreover, the modular nature of the converter can achieve redundancy in the system, and thereby, the reliability can be enhanced to a great extent. The circuit has a high operating efficiency (\u3e95%), and it is possible to integrate multiple voltage sources and loads at the same time. Thus, the converter could be considered as a combination of a power electronic converter and a power management system. In addition to the new dc-dc converter topology, a new pair of modular blocks defined as switching cells is presented in this dissertation. This pair of switching cells can be used to analyze many power electronic circuits, and some new designs can be formed using those switching cells in various combinations. Using these switching cells, many power electronic circuits can be made modular, and the modeling and analysis become easier

    THE DEVELOPMENT OF A MECHATRONICS AND MATERIAL HANDLING COURSE: LABORATORY EXPERIMENTS AND PROJECTS

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    Mechatronic systems integrate technologies from a variety of engineering disciplines to create solutions to challenging industrial problems. The material handling industry utilizes mechatronics to move, track, and manipulate items in factories and distribution centers. Material handling systems, because of their use of programmable logic controllers (PLC), PLC networks, industrial robotics, and other mechatronic elements, are a natural choice for a college instructional environment. This thesis offers insight and guidance for mechatronic activities introduced in a laboratory setting. A series of eight laboratory experiments have been created to introduce PLCs, robotics, electric circuits, and data acquisition fundamentals. In-depth case studies synthesize the technologies and interpersonal skills together to create a flexible material handling system. Student response to the course and laboratory material was exceptional. A pre and post course questionnaire was administered which covered topics such as teamwork, human factors, business methods, and various engineering related questions. Quantitative scores resulting from these questionnaires showed a marked improvement by students, especially in regards to technical/engineering questions. The responses from students generally indicated an excitement about course material and a thorough understanding of the various syllabus topics. In this thesis, the multi-disciplinary mechatronics (and material handling systems) laboratory will be presented. An in-depth examination of each laboratory will be offered as well as the discussion of two material handling case studies. The Appendixes contain the PLC and robot code for a order fulfillment case study

    Coordinated Science Laboratory progress report for December 1965, January, and February 1966

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    Studies in mechanical damping in possible gyro materials, electron scattering from surface of tungsten, and control system
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