2,763 research outputs found

    Meter for use in detecting tension in straps having predetermined elastic characteristics

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    A meter for detecting tension in elastic bodies, especially in fabric straps employed as tie down straps for stowed objects is presented. The meter is characterized by a pair of elongated arms coupled together for pivotal motion about a common axis in a common plane and a strap receiver located at adjacent ends of the arms for receiving and securing adjacent portions of the strap. The receivers are supported by the arms for motion along intersecting arcs, and motion detection means is located at the opposite ends of the arms for detecting the magnitude of the motion imparted to the receivers as the strap is placed in tension

    Fast, sensitive discovery of conserved genome-wide motifs

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    Regulatory sites that control gene expression are essential to the proper functioning of cells, and identifying them is critical for modeling regulatory networks. We have developed Magma (Multiple Aligner of Genomic Multiple Alignments), a software tool for multiple species, multiple gene motif discovery. Magma identifies putative regulatory sites that are conserved across multiple species and occur near multiple genes throughout a reference genome. Magma takes as input multiple alignments that can include gaps. It uses efficient clustering methods that make it about 70 times faster than PhyloNet, a previous program for this task, with slightly greater sensitivity. We ran Magma on all non-coding DNA conserved between Caenorhabditis elegans and five additional species, about 70 Mbp in total, in <4 h. We obtained 2,309 motifs with lengths of 6–20 bp, each occurring at least 10 times throughout the genome, which collectively covered about 566 kbp of the genomes, approximately 0.8% of the input. Predicted sites occurred in all types of non-coding sequence but were especially enriched in the promoter regions. Comparisons to several experimental datasets show that Magma motifs correspond to a variety of known regulatory motifs

    Mapping Meiotic Single-Strand DNA Reveals a New Landscape of DNA Double-Strand Breaks in Saccharomyces cerevisiae

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    DNA double-strand breaks (DSBs), which are formed by the Spo11 protein, initiate meiotic recombination. Previous DSB-mapping studies have used rad50S or sae2Δ mutants, which are defective in break processing, to accumulate Spo11-linked DSBs, and report large (≥ 50 kb) “DSB-hot” regions that are separated by “DSB-cold” domains of similar size. Substantial recombination occurs in some DSB-cold regions, suggesting that DSB patterns are not normal in rad50S or sae2Δ mutants. We therefore developed a novel method to map genome-wide, single-strand DNA (ssDNA)–associated DSBs that accumulate in processing-capable, repair-defective dmc1Δ and dmc1Δ rad51Δ mutants. DSBs were observed at known hot spots, but also in most previously identified “DSB-cold” regions, including near centromeres and telomeres. Although approximately 40% of the genome is DSB-cold in rad50S mutants, analysis of meiotic ssDNA from dmc1Δ shows that most of these regions have substantial DSB activity. Southern blot assays of DSBs in selected regions in dmc1Δ, rad50S, and wild-type cells confirm these findings. Thus, DSBs are distributed much more uniformly than was previously believed. Comparisons of DSB signals in dmc1, dmc1 rad51, and dmc1 spo11 mutant strains identify Dmc1 as a critical strand-exchange activity genome-wide, and confirm previous conclusions that Spo11-induced lesions initiate all meiotic recombination

    Comparison of Communications Styles Amongst Students in Allied Health Professions Programs: How Do Our Students Communicate with Other Healthcare Providers?

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    Background: Optimal patient outcomes require communication between providers in multiple professions to initiate referrals, communicate patient treatment, and coordinate care. While there is a clear need for increased understanding of the terminology, skills, and scopes of practice of professional colleagues, these tools are of limited effectiveness if there is poor interpersonal communication between team members. Multiple bodies for Interprofessional Practice and Education (IPP/IPE) identify communication skills as an integral part of education. In fact, the third competency domain set down by the Interprofessional Education Collaborative, Interprofessional Communication, states that professionals should, &ldquo;Recognize how one&rsquo;s own uniqueness, including experience level, expertise, culture, power, and hierarchy within the healthcare team, contributes to effective communication, conflict resolution, and positive interprofessional working relationships&rdquo; [1].Methods and Findings: As part of a required interprofessional competence course, first-year students in ten health professions programs completed the Personal Coaching Style Inventory (PSCI) to self-identify personal communication styles. A series of one-way analysis of variance (ANOVA) analyses followed by Tukey post-hoc analyses were performed in order to identify significant differences in PSCI component scores between programs. Within groups, students discussed personal and cohort-wide findings as they impact teamwork. The majority of students identified with the Mediator style. Differences in style were also found in relation to profession, gender, and race. The activity prompted discussion of varied roles in team dynamics, and how differences in style could affect interprofessional teamwork.Conclusions: Self-awareness of personal communication styles as well as predominant styles of other health professions may enhance interprofessional communication\skills. The skill with which students approach their team roles in heterogeneous groups following graduation has the potential to increase team functionality and patient outcomes

    Fatigue analysis of multiple site damage at a row of holes in a wide panel

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    This paper is concerned with predicting the fatigue life of unstiffened panels which contain multiple site damage (MSD). The initial damage consists of through-the-thickness cracks emanating from a row of holes in the center of a finite width panel. A fracture mechanics analysis has been developed to predict the growth, interaction, and coalescence of the various cracks which propagate in the panel. A strain-life analysis incorporating Neuber's rule for notches, and Miner's rule for cumulative damage, is also employed to predict crack initiation for holes without initial cracking. This analysis is compared with the results of a series of fatigue tests on 2024-T3 aluminum panels, and is shown to do an excellent job of predicting the influence of MSD on the fatigue life of nine inch wide specimens. Having established confidence in the ability to analyze the influence of MSD on fatigue life, a parametric study is conducted to examine the influence of various MSD scenarios in an unstiffened panel. The numerical study considered 135 cases in all, with the parametric variables being the applied cyclic stress level, the lead crack geometry, and the number and location of MSD cracks. The numerical analysis provides details for the manner in which lead cracks and MSD cracks grow and coalesce leading to final failure. The results indicate that MSD located adjacent to lead cracks is the most damaging configuration, while for cases without lead cracks, MSD clusters which are not separated by uncracked holes are most damaging

    Temporal control of Wnt signaling is required for habenular neuron diversity and brain asymmetry

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    Precise temporal coordination of signaling processes is pivotal for cellular differentiation during embryonic development. A vast number of secreted molecules are produced and released by cells and tissues, and travel in the extracellular space. Whether they induce a signaling pathway and instruct cell fate, however, depends on a complex network of regulatory mechanisms, which are often not well understood. The conserved bilateral left-right asymmetrically formed habenulae of the zebrafish are an excellent model for investigating how signaling control facilitates the generation of defined neuronal populations. Wnt signaling is required for habenular neuron type specification, asymmetry and axonal connectivity. The temporal regulation of this pathway and the players involved have, however, remained unclear. We find that tightly regulated temporal restriction of Wnt signaling activity in habenular precursor cells is crucial for the diversity and asymmetry of habenular neuron populations. We suggest a feedback mechanism whereby the tumor suppressor Wnt inhibitory factor Wif1 controls the Wnt dynamics in the environment of habenular precursor cells. This mechanism might be common to other cell types, including tumor cells

    Paper Session I-C - Comparison of Surface Resistivity and Triboelectric Charge Generation Characteristics of Materials

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    Electrostatic discharge can be a significant threat to electronic components, equipment and personnel, especially when working around flammable materials. The development of ways to predict the susceptibility of materials to generate significant charge is important for the safety of these personnel and equipment. The classification of materials as conductors or insulators is based on the surface resistivity of the materials. Though surface resistivity is an important piece of information when choosing electrostatically safe materials, this classification system does not provide any information as to the probability of the materials to generate charge when placed in contact with other materials (triboelectric charging). Without that information, the probability for hazardous electrostatic discharge to occur is not known. In this paper we show that there is no significant correlation between surface resistivity and triboelectric charge generation and emphasize the need for a test method to predict the susceptibility of materials for triboelectric charge generation in order to better evaluate a material’s propensity to cause an electrostatic discharge

    Partial Model of Insulator/Insulator Contact Charging

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    Two papers present a two-phase equilibrium model that partly explains insulator/ insulator contact charging. In this model, a vapor of ions within a gas is in equilibrium with a submonolayer of ions of the same species that have been adsorbed on the surface of an insulator. The surface is modeled as having localized states, each with a certain energy of adsorption for an ion. In an earlier version of the model described in the first paper, the ions do not interact with each other. Using the grand canonical ensemble, the chemical potentials of both vapor and absorbed phases are derived and equated to determine the vapor pressure. If a charge is assigned to the vapor particles (in particular, if single ionization is assumed), then the surface charge density associated with adsorbed ions can be calculated as a function of pressure. In a later version of the model presented in the second paper, the submodel of the vapor phase is extended to include electrostatic interactions between vapor ions and adsorbed ones as well as the screening effect, at a given distance from the surface, of ions closer to the surface. Theoretical values of this model closely match preliminary experimental data on the discharge of insulators as a function of pressure

    Entropic phase separation of linked beads

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    We study theoretically a model system of a transient network of microemulsion droplets connected by telechelic polymers and explain recent experimental findings. Despite the absence of any specific interactions between either the droplets or polymer chains, we predict that as the number of polymers per drop is increased, the system undergoes a first order phase separation into a dense, highly connected phase, in equilibrium with dilute droplets, decorated by polymer loops. The phase transition is purely entropic and is driven by the interplay between the translational entropy of the drops and the configurational entropy of the polymer connections between them. Because it is dominated by entropic effects, the phase separation mechanism of the system is extremely robust and does not depend on the particlular physical realization of the network. The discussed model applies as well to other polymer linked particle aggregates, such as nano-particles connected with short DNA linkers

    Smoothened receptor signaling regulates the developmental shift of GABA polarity in rat somatosensory cortex.

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    This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordSonic Hedgehog (Shh) and its patched-smoothened receptor complex control a variety of functions in the developing central nervous system such as neural cell proliferation and differentiation. Recently, Shh signaling components have been found to be expressed at the synaptic level in the postnatal brain, suggesting a potential role in the regulation of synaptic transmission. Using in utero electroporation of constitutively active and negative-phenotype forms of the Shh signal transducer smoothened (Smo), we studied the role of Smo signaling in the development and maturation of GABAergic transmission in the somatosensory cortex. Our results show that enhancing Smo activity during development accelerates the shift from depolarizing to hyperpolarizing GABA in dependence on functional expression of potassium-chloride cotransporter type 2 (KCC2). On the other hand, blocking Smo activity maintains GABA response in a depolarizing state in mature cortical neurons resulting in altered chloride homeostasis and increased seizure susceptibility. This study reveals an unexpected function of Smo signaling on the regulation of chloride homeostasis through the control of KCC2 cell surface stability and on the timing of the GABA inhibitory/excitatory shift in brain maturation
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