324 research outputs found

    Asymmetrical Inter-Symbol Interference in Macro-Scale Molecular Communications

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    The experience of being a guide dog puppy raiser volunteer: a longitudinal qualitative collective case study

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    There are no published studies that consider the experiences of guide dog puppy raisers. As these people are volunteers, their continued willingness to participate in the training of dogs for assisting the vision impaired and blind is essential for the viability of guide dog schools around the world. Using a qualitative, longitudinal methodology, data were collected from nine guide dog puppy raisers at four time points: before receiving the puppy, one week, then three months after the puppy arrived, and 13 months after the puppy arrived (at which time all puppies had left the raisers). Participants reported more challenges than benefits in raising the puppies. Volunteering to be a guide dog puppy raiser may not be the pleasant experience that is anticipated when community members first offer their services. Understanding what it is like to be a puppy raiser and working towards ways in which to address problems is essential, given that, without volunteers to train and care for puppies, vision impaired and blind people would not have access to guide dogs.Anna Chur-Hansen, Lucy-Kate Werner, Clare E. McGuiness, and Susan Haze

    A chemical alphabet for macromolecular communications.

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    Molecular communications in macroscale environments is an emerging field of study driven by the intriguing prospect of sending coded information over olfactory networks. For the first time, this article reports two signal modulation techniques (on–off keying—OOK, and concentration shift keying—CSK) which have been used to encode and transmit digital information using odors over distances of 1–4 m. Molecular transmission of digital data was experimentally investigated for the letter “r” with a binary value of 01110010 (ASCII) for a gas stream network channel (up to 4 m) using mass spectrometry (MS) as the main detection-decoding system. The generation and modulation of the chemical signals was achieved using an automated odor emitter (OE) which is based on the controlled evaporation of a chemical analyte and its diffusion into a carrier gas stream. The chemical signals produced propagate within a confined channel to reach the demodulator—MS. Experiments were undertaken for a range of volatile organic compounds (VOCs) with different diffusion coefficient values in air at ambient conditions. Representative compounds investigated include acetone, cyclopentane, and n-hexane. For the first time, the binary code ASCII (American Standard Code for Information Interchange) is combined with chemical signaling to generate a molecular representation of the English alphabet. Transmission experiments of fixed-width molecular signals corresponding to letters of the alphabet over varying distances are shown. A binary message corresponding to the word “ion” was synthesized using chemical signals and transmitted within a physical channel over a distance of 2 m

    Understanding workflow in telehealth video visits: Observations from the IDEATel project

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    AbstractHome telemedicine is an emerging healthcare paradigm that has the potential to transform the treatment of chronic illness. The purpose of this paper is to: (1) develop a theoretical and methodological framework for studying workflow in telemediated clinician–patient encounters drawing on a distributed cognition approach and (2) employ the framework in an in-depth analysis of workflow in the IDEATel project, a telemedicine program for older adults with diabetes. The methods employed in this research included (a) videotaped observations of 27 nurse–patient encounters and (b) semi-structured interviews with participants. The analyses were used to provide a descriptive analysis of video visits, understand the mediating role of different technologies and to characterize the ways in which artifacts and representations are used to understand the state of the patient. The study revealed barriers to productive use of telehealth technology as well as adaptations that circumvented such limitations. This research has design implications for: (a) improving the coordination of communication and (b) developing tools that better integrate and display information. Although home telemedicine programs will differ in important respects, there are invariant properties across such systems. Explicating these properties can serve as a needs requirement analysis to develop more effective systems and implementation plans

    K-shell photoionization of ground-state Li-like carbon ions [C3+^{3+}]: experiment, theory and comparison with time-reversed photorecombination

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    Absolute cross sections for the K-shell photoionization of ground-state Li-like carbon [C3+^{3+}(1s2^22s 2^2S)] ions were measured by employing the ion-photon merged-beams technique at the Advanced Light Source. The energy ranges 299.8--300.15 eV, 303.29--303.58 eV and 335.61--337.57 eV of the [1s(2s2p)3^3P]2^2P, [1s(2s2p)1^1P]2^2P and [(1s2s)3^3S 3p]2^2P resonances, respectively, were investigated using resolving powers of up to 6000. The autoionization linewidth of the [1s(2s2p)1^1P]2^2P resonance was measured to be 27±527 \pm 5 meV and compares favourably with a theoretical result of 26 meV obtained from the intermediate coupling R-Matrix method. The present photoionization cross section results are compared with the outcome from photorecombination measurements by employing the principle of detailed balance.Comment: 3 figures and 2 table

    Cerebrospinal fluid cannot be used to distinguish inflammatory myelitis from congestive myelopathy due to spinal dural arteriovenous fistula: case series.

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    Patients with congestive myelopathy due to spinal dural arteriovenous fistula (SDAVF) typically present with progressive sensory and motor disturbance in association with sphincter dysfunction. Spinal MRI usually shows longitudinally extensive T2 signal change. Here, we report four patients with progressive myelopathy due to SDAVF who also presented with findings on cerebrospinal fluid (CSF) examination suggestive of an inflammatory aetiology. Such CSF findings in SDAVF are important to recognise, to avoid the erroneous diagnosis of an inflammatory myelitis and inappropriate treatment with immunosuppression. SDAVF can be difficult to detect and may require repeated investigation, with formal angiography as the gold standard

    Prophylactic Intra-Aortic Balloon Counterpulsation in High Risk Cardiac Surgery: The PINBALL Pilot Multicentre, Registry-Linked, Randomised, Controlled Feasibility Trial

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    Background: Prophylactic intra-aortic balloon counterpulsation (IABC) is commonly used in selected patients undergoing coronary artery bypass graft (CABG) surgery, but definitive evidence is lacking. The aim of the multicentre PINBALL Pilot randomised controlled trial (RCT) was to assess the feasibility of performing a definitive trial to address this question. Methods: Patients listed for CABG surgery with impaired left ventricular function and at least one additional risk factor for postoperative low cardiac output syndrome were eligible for inclusion if the treating surgical team was uncertain as to the benefit of prophylactic IABC. The primary outcome of feasibility was based on exceeding a pre-specified recruitment rate, protocol compliance and follow-up. Results: The recruitment rate of 0.5 participants per site per month did not meet the feasibility threshold of two participants per site per month and the study was stopped early after enrolment of 24 out of the planned sample size of 40 participants. For 20/24 (83%) participants, preoperative IABC use occurred according to study assignment. Six (6)-month follow-up was available for all enrolled participants, [IABC 1 death (8%) vs. control 1 death (9%), p = 0.95]. Conclusion: The PINBALL Pilot recruitment rate was insufficient to demonstrate feasibility of a multicentre RCT of prophylactic IABC in high risk patients undergoing CABG surgery

    Mathematical models for estimating effective diffusion parameters of spherical drug delivery devices

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    Mathematical modeling of drug delivery is of increasing academic and industrial importance in manyaspects. In this paper, we propose an optimization approach for the estimation of the parameters characterizing the diffusion process of a drug from a spherical porous polymer device to an external finite volume. The approach is based on a nonlinear least-squares method and a novel mathematical model which takes into consideration both boundary layer effect and initial burst phenomenon. Ananalytical solution to the model is derived and a formula for the ratio of the mass released in a given time interval and the total mass released in infinite time is also obtained. The approach has been tested using experimental data of the diffusion of prednisolone 21-hemisuccinate sodium saltfrom spherical devices made of porous poly(2-hydroxyethyl methacrylate) hydrogels. The effectiveness and accuracy of the method are well demonstrated by the numerical results. The model was used to determine the diffusion parameters including the effective diffusion coefficient of the drug from a series of devices that vary in both the porous structure and the drug loading levels. The computed diffusion parameters are discussed in relation to the physical properties of the devices

    Linking Auxin with Photosynthetic Rate via Leaf Venation

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    International audienceLand plants lose vast quantities of water to the atmosphere during photosynthetic gas exchange. In angiosperms, a complex network of veins irrigates the leaf, and it is widely held that the density and placement of these veins determines maximum leaf hydraulic capacity and thus maximum photosynthetic rate. This theory is largely based on interspecific comparisons and has never been tested using vein mutants to examine the specific impact of leaf vein morphology on plant water relations. Here we characterize mutants at the Crispoid (Crd) locus in pea (Pisum sativum), which have altered auxin homeostasis and activity in developing leaves, as well as reduced leaf vein density and aberrant placement of free-ending veinlets. This altered vein phenotype in crd mutant plants results in a significant reduction in leaf hydraulic conductance and leaf gas exchange. We find Crispoid to be a member of the YUCCA family of auxin biosynthetic genes. Our results link auxin biosynthesis with maximum photosynthetic rate through leaf venation and substantiate the theory that an increase in the density of leaf veins coupled with their efficient placement can drive increases in leaf photosynthetic capacity
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