1,739 research outputs found
The Use of Cream in the Investigation of Human Error in Aviation Events: a Case Study
To investigate Human Factors issues of the Traffic Alert and Collision Avoidance System (TCAS), a part-task simulation has been conducted. The analysis method employed was based on the CREAM principles and included the following steps: Predictive analysis, Simulations, Data analysis, Retrospective analysis. The project called ARCADES , presented in this paper, concerns the errors identification and research of causes. The collective work based on CREAM is composed of four steps alternating between work in pairs and plenary session: the events identification and classification, consensus on the events to be analyzed, the retrospective analysis, and the mutual analysis. The work group was composed of pilots, controllers, investigators and Human Factors experts. The analysis was based on the data collected during the simulations: video recordings, questionnaires, audio recording of debriefing. Concerning the identification step, results show the interest of the clear distinction between causes and consequences, as it exists in CREAM. Indeed, it enables to bind the analysts to objectivity in the identification and the calling of the events. Inter-pairs variability remains important for the three scenarios studied. Participants agreed on the interest of the method concerning the search of causes. The method enables to pursue analyses more deeply and more exhaustively, results show that the method guides towards systemic causes. Results also emphasize the complementarity of different points of view and the interest of a collective approach
Superfast Vocal Muscles Control Song Production in Songbirds
Birdsong is a widely used model for vocal learning and human speech, which exhibits high temporal and acoustic diversity. Rapid acoustic modulations are thought to arise from the vocal organ, the syrinx, by passive interactions between the two independent sound generators or intrinsic nonlinear dynamics of sound generating structures. Additionally, direct neuromuscular control could produce such rapid and precisely timed acoustic features if syringeal muscles exhibit rare superfast muscle contractile kinetics. However, no direct evidence exists that avian vocal muscles can produce modulations at such high rates. Here, we show that 1) syringeal muscles are active in phase with sound modulations during song over 200 Hz, 2) direct stimulation of the muscles in situ produces sound modulations at the frequency observed during singing, and that 3) syringeal muscles produce mechanical work at the required frequencies and up to 250 Hz in vitro. The twitch kinematics of these so-called superfast muscles are the fastest measured in any vertebrate muscle. Superfast vocal muscles enable birds to directly control the generation of many observed rapid acoustic changes and to actuate the millisecond precision of neural activity into precise temporal vocal control. Furthermore, birds now join the list of vertebrate classes in which superfast muscle kinetics evolved independently for acoustic communication
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Human Vault Nanoparticle Targeted Delivery of Antiretroviral Drugs to Inhibit Human Immunodeficiency Virus Type 1 Infection.
"Vaults" are ubiquitously expressed endogenous ribonucleoprotein nanoparticles with potential utility for targeted drug delivery. Here, we show that recombinant human vault nanoparticles are readily engulfed by certain key human peripheral blood mononuclear cells (PBMC), predominately dendritic cells, monocytes/macrophages, and activated T cells. As these cell types are the primary targets for human immunodeficiency virus type 1 (HIV-1) infection, we examined the utility of recombinant human vaults for targeted delivery of antiretroviral drugs. We chemically modified three different antiretroviral drugs, zidovudine, tenofovir, and elvitegravir, for direct conjugation to vaults. Tested in infection assays, drug-conjugated vaults inhibited HIV-1 infection of PBMC with equivalent activity to free drugs, indicating vault delivery and drug release in the cytoplasm of HIV-1-susceptible cells. The ability to deliver functional drugs via vault nanoparticle conjugates suggests their potential utility for targeted drug delivery against HIV-1
A large-momentum-transfer matter-wave interferometer to measure the effect of gravity on positronium
This paper reports the study of a new interferometric configuration to measure the effect of gravity on positronium. A Mach–Zehnder matter-wave interferometer has been designed to operate with single-photon transitions and to transfer high momentum to a 200 eV positronium beam. The work shows the results and methods used to simulate the interferometer and estimate the
operating parameters and the time needed to perform the experiment. It has been estimated that within less than 1 year, the acquisition time is sufficient to achieve a 10% accuracy level in measuring positronium gravitational acceleration, even with a poorly collimated beam, which is significant for theoretical models describing matter–antimatter symmetry. These results pave the way for single photon transition large momentum transfer interferometry with fast atomic beams, which is particularly useful for studies with antimatter and unstable atoms
Loss and revival of coherence in the interaction between a positron beam and a photon field
We study the interaction between a positron beam in the single-particle regime in an interferometric configuration and a microwave electromagnetic field. We discuss the conditions under which quantum interference can be affected by the field and we outline its possible experimental study in the framework of QUantum interferometry and gravitation
with Positrons and LASers (QUPLAS) experiment
Lymphocyte-Derived Exosomal MicroRNAs Promote Pancreatic β Cell Death and May Contribute to Type 1 Diabetes Development.
Type 1 diabetes is an autoimmune disease initiated by the invasion of pancreatic islets by immune cells that selectively kill the β cells. We found that rodent and human T lymphocytes release exosomes containing the microRNAs (miRNAs) miR-142-3p, miR-142-5p, and miR-155, which can be transferred in active form to β cells favoring apoptosis. Inactivation of these miRNAs in recipient β cells prevents exosome-mediated apoptosis and protects non-obese diabetic (NOD) mice from diabetes development. Islets from protected NOD mice display higher insulin levels, lower insulitis scores, and reduced inflammation. Looking at the mechanisms underlying exosome action, we found that T lymphocyte exosomes trigger apoptosis and the expression of genes involved in chemokine signaling, including Ccl2, Ccl7, and Cxcl10, exclusively in β cells. The induction of these genes may promote the recruitment of immune cells and exacerbate β cell death during the autoimmune attack. Our data point to exosomal-miRNA transfer as a communication mode between immune and insulin-secreting cells
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