170 research outputs found

    Carbon Dioxide Expulsion by Ceanothus spinosus in Response to Predawn Sunlight

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    In our experiment we studied the respiratory qualities of green bark ceanothus (Ceanothus spinosus). Plants are generally thought to undergo respiration during the night, building up carbon dioxide stores that are released in response to light. In resprouts with large root crowns, such as C. spinosus, we expected to see large amounts of carbon dioxide released right after dawn. This can be shown with the use of a portable gas exchange system. In C. spinosus, we compared normal respiration rates, based on carbon dioxide expulsion, to values obtained at predawn. We were able to show that there is significant carbon dioxide expulsion that occurs in response to predawn sunlight. We predict this may be related to very high metabolic rates of the roots as the plant resprouts

    Building and Characterizing Graphene Nanomechanical Resonator Networks

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    Networks of nanoelectromechanical (NEMS) resonators are useful analogs for a variety of many- body systems and enable impactful applications in sensing, phononics, and mechanical information processing. Two main challenges are currently limiting progress toward realizing practical NEMS networks. The first is building a platform of interconnected resonators that is scalable in both size and tunability. The second is spatially quantifying the mechanical parameters of each resonator in the network and their coupling. In this work, we address these two main challenges with a novel scalable platform to build the network and a compatible method to characterize mechanical parameters. Together, this work fills in a vital gap for the experimental realization of programmable NEMS networks.We first present a novel platform of suspended graphene resonators that hosts strong coupling and is scalable in 2D. In this platform, we suspended graphene over pillar arrays, in which large areas of suspended graphene act as drumhead resonators and shared membrane between adjacent resonators allows for direct coupling through strain. We demonstrate the versatility advantages of our graphene-based resonator network by providing evidence of strong coupling through two different tuning methods. We demonstrate the 2D scalability potential of this platform with evidence of coupling between three resonators. Finally, we show noteworthy coupling dynamics of inter-resonator higher order mode coupling that is enabled by our versatile platform. We then demonstrate a scalable optical technique to spatially characterize graphene NEMS network. In this technique, we read out the fixed-frequency collective response as a single vector. Using just two response vectors, we solve for the site-specific elasticity, mass, damping, and coupling parameters of network clusters. Compared to multiple regression, our algebraic fully characterizes the network parameters without requiring a priori parameter estimates or iterative computation. We apply this technique to single-resonator and coupled-pair clusters and find excellent agreement with expected parameter values and spectral response. Our approach offers a direct means to accurately characterize both classical and quantum resonator systems

    Effectiveness of Pelvic Floor Exercises on Women with Urinary Incontinence :

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    Effectiveness of Pelvic Floor Exercises in Women with Urinary Incontinence Purpose: Urinary incontinence is common in women; especially those who have had one or more vaginal deliveries. The purpose of our case study was to measure the effectiveness of pelvic floor exercises and biofeedback in women with urinary incontinence (VI) in a rural midwest physical therapy clinic. Methods: Patients participating in this study were referred to a physical therapy clinic by their physician for a urinary incontinence program. During the initial evaluations, baseline biofeedback readings were recorded and home exercise programs were given. Patients were then seen for follow-ups at approximately two weeks, four weeks, and three months thereafter. Final biofeedback testing and completion of the three inventories were performed at the three-month follow up. Results: Due to a small sample size, we chose to display our results on an individual case basis. Case study 1 showed improvement subjectively, however, did not improve in objective measures. Case studies 2 and 3 showed improvement both in subjective and objective measures. Discussion: Limitations of our study included a small sample size, rural community environment, lack of normative data for biofeedback, and time constraints. All three patients reported subjective improvement from the UI program, and the continuation of this study will help to determine the significance of this physical therapy intervention

    Frog Model Wakeup Time on the Complete Graph

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    The frog model is a system of random walks where active particles set sleeping particles in motion. On the complete graph with n vertices it is equivalent to a well-understood rumor spreading model. We given an alternate and elementary proof that the wakeup time, that is, the expected time for every particle to be activated, is &Theta(log n). Additionally, we give an explicit distributional equation for the wakeup time as a mixture of geometric random variables

    Pathogenicity locus, core genome, and accessory gene contributions to Clostridium difficile virulence

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    Clostridium difficile is a spore-forming anaerobic bacterium that causes colitis in patients with disrupted colonic microbiota. While some individuals are asymptomatic C. difficile carriers, symptomatic disease ranges from mild diarrhea to potentially lethal toxic megacolon. The wide disease spectrum has been attributed to the infected host’s age, underlying diseases, immune status, and microbiome composition. However, strain-specific differences in C. difficile virulence have also been implicated in determining colitis severity. Because patients infected with C. difficile are unique in terms of medical history, microbiome composition, and immune competence, determining the relative contribution of C. difficile virulence to disease severity has been challenging, and conclusions regarding the virulence of specific strains have been inconsistent. To address this, we used a mouse model to test 33 clinical C. difficile strains isolated from patients with disease severities ranging from asymptomatic carriage to severe colitis, and we determined their relative in vivo virulence in genetically identical, antibiotic-pretreated mice. We found that murine infections with C. difficile clade 2 strains (including multilocus sequence type 1/ribotype 027) were associated with higher lethality and that C. difficile strains associated with greater human disease severity caused more severe disease in mice. While toxin production was not strongly correlated with in vivo colonic pathology, the ability of C. difficile strains to grow in the presence of secondary bile acids was associated with greater disease severity. Whole-genome sequencing and identification of core and accessory genes identified a subset of accessory genes that distinguish high-virulence from lower-virulence C. difficile strains

    Progress and Prospects for a Nucleic Acid Screening Test Set

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    Objective: DNA synthesis companies screen orders to detect controlled sequences with misuse risks. Assessing screening accuracy is challenging owing to the breadth of biological risks and ambiguities in risk definitions. Here, we detail an International Gene Synthesis Consortium working group’s rationale and process to develop a prototype DNA synthesis screening test dataset, aiming to establish a baseline of screening system accuracy to compare with various screening approaches.Methodology: Construction of the prototype test dataset involved four tool developers screening nucleic acid sequences from three taxonomic clusters of controlled organisms (Orbivirus, Francisella tularensis, and Coccidioides). Results were mapped onto predefined, comparable categories, checking for consensus or conflicts. Conflicts were grouped based on gene annotation and resolved through discussion.Results: The process highlighted several long-standing challenges in DNA synthesis screening, including the qualitative differences in approaches taken by screening tools. Our findings highlight the lack of clarity in assessing pathogen sequences with respect to regulatory control language, compounded by scientific uncertainty. We illustrate the current degree of consensus and existing challenges using classification statistics and specific examples.Conclusions and Next Steps: This prototype underscores the necessity of expert-regulator coordination in assessing gene-associated risks, offering a template for creating test sets across all taxonomic groups on international control lists. Expanding the working group would enrich dataset comprehensiveness, enabling a transition from species-focused to function-focused regulatory controls. This sets the foundation for quality control, certification, and improved risk assessment in DNA synthesis screening

    PIN6 is required for nectary auxin response and short stamen development

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98417/1/tpj12184-sup-0001-FigS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/98417/2/tpj12184.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/98417/3/tpj12184-sup-0004-FigS4.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/98417/4/tpj12184-sup-0003-FigS3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/98417/5/tpj12184-sup-0002-FigS2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/98417/6/tpj12184-sup-0005-FigS5.pd

    Human severe sepsis cytokine mixture increases β2-integrin-dependent polymorphonuclear leukocyte adhesion to cerebral microvascular endothelial cells in vitro.

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    INTRODUCTION: Sepsis-associated encephalopathy (SAE) is a state of acute brain dysfunction in response to a systemic infection. We propose that systemic inflammation during sepsis causes increased adhesion of leukocytes to the brain microvasculature, resulting in blood-brain barrier dysfunction. Thus, our objectives were to measure inflammatory analytes in plasma of severe sepsis patients to create an experimental cytokine mixture (CM), and to use this CM to investigate the activation and interactions of polymorphonuclear leukocytes (PMN) and human cerebrovascular endothelial cells (hCMEC/D3) in vitro. METHODS: The concentrations of 41 inflammatory analytes were quantified in plasma obtained from 20 severe sepsis patients and 20 age- and sex-matched healthy controls employing an antibody microarray. Two CMs were prepared to mimic severe sepsis (SSCM) and control (CCM), and these CMs were then used for PMN and hCMEC/D3 stimulation in vitro. PMN adhesion to hCMEC/D3 was assessed under conditions of flow (shear stress 0.7 dyn/cm(2)). RESULTS: Eight inflammatory analytes elevated in plasma obtained from severe sepsis patients were used to prepare SSCM and CCM. Stimulation of PMN with SSCM led to a marked increase in PMN adhesion to hCMEC/D3, as compared to CCM. PMN adhesion was abolished with neutralizing antibodies to either β2 (CD18), αL/β2 (CD11α/CD18; LFA-1) or αM/β2 (CD11β/CD18; Mac-1) integrins. In addition, immune-neutralization of the endothelial (hCMEC/D3) cell adhesion molecule, ICAM-1 (CD54) also suppressed PMN adhesion. CONCLUSIONS: Human SSCM up-regulates PMN pro-adhesive phenotype and promotes PMN adhesion to cerebrovascular endothelial cells through a β2-integrin-ICAM-1-dependent mechanism. PMN adhesion to the brain microvasculature may contribute to SAE
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