501 research outputs found

    On the Complexity of Solving Zero-Dimensional Polynomial Systems via Projection

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    Given a zero-dimensional polynomial system consisting of n integer polynomials in n variables, we propose a certified and complete method to compute all complex solutions of the system as well as a corresponding separating linear form l with coefficients of small bit size. For computing l, we need to project the solutions into one dimension along O(n) distinct directions but no further algebraic manipulations. The solutions are then directly reconstructed from the considered projections. The first step is deterministic, whereas the second step uses randomization, thus being Las-Vegas. The theoretical analysis of our approach shows that the overall cost for the two problems considered above is dominated by the cost of carrying out the projections. We also give bounds on the bit complexity of our algorithms that are exclusively stated in terms of the number of variables, the total degree and the bitsize of the input polynomials

    Impression Cytology of the Lid Wiper Area

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    Muntz, A., van Doorn, K., Subbaraman, L. N., & Jones, L. W. (2016). Impression Cytology of the Lid Wiper Area. Journal of Visualized Experiments, (114). https://doi.org/10.3791/54261Few reports on the cellular anatomy of the lid wiper (LW) area of the inner eyelid exist and only one report makes use of cytological methods. The optimization of a method of collecting, staining and imaging cells from the LW region using impression cytology (IC) is described in this study. Cells are collected from the inner surface of the upper eyelid of human subjects using hydrophilic polytetrafluoroethylene (PTFE) membranes, and stained with cytological dyes to reveal the presence of goblet cells, mucins, cell nuclei and various degrees of pre- and para-keratinization. Immunocytochemical dyes show cell esterase activity and compromised cell membranes by the use of a confocal scanning laser microscope. Up to 100 microscopic digital images are captured for each sample and stitched into a high-resolution, large scale image of the entire IC span. We demonstrate a higher sensitivity of IC than reported before, appropriate for identifying cellular morphologies and metabolic activity in the LW area. To our knowledge, this is the first time this selection of fluorescent dyes was used to image LW IC membranes. This protocol will be effective in future studies to reveal undocumented details of the LW area, such as assessing cellular particularities of contact lens wearers or patients with dry eye or lid wiper epitheliopathy

    Release of Ciprofloxacin and Moxifloxacin From Daily Disposable Contact Lenses From an In Vitro Eye Model

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    Bajgrowicz, M., Phan, C.-M., Subbaraman, L. N., & Jones, L. (2015). Release of Ciprofloxacin and Moxifloxacin From Daily Disposable Contact Lenses From an In Vitro Eye Model. Investigative Opthalmology & Visual Science, 56(4), 2234. https://doi.org/10.1167/iovs.15-16379Purpose.: To analyze the release of two fluoroquinolones, ciprofloxacin and moxifloxacin, from conventional hydrogel (CH) and silicone hydrogel (SH) daily disposable contact lenses (CLs), comparing release from a fixed-volume vial and a novel in vitro eye model. Methods.: Four CH CLs (nelfilcon A, omafilcon A, etafilcon A, ocufilcon B) and three SH CLs (somofilcon A, narafilcon A, delefilcon A) were used. The lenses were incubated in drug solutions for 24 hours. After the incubation period, the lenses were placed in two release conditions: (1) a vial containing 4.8 mL PBS for 24 hours and (2) an in vitro eye model with a flow rate at 4.8 mL over 24 hours. Results.: Release in the vial for both drugs was rapid, reaching a plateau between 15 minutes and 2 hours for all lenses. In contrast, under physiological flow conditions, a constant and slow release was observed over 24 hours. The amounts of ciprofloxacin released from the lenses ranged between 49.6 ± 0.7 and 62.8 ± 0.3 μg per lens in the vial, and between 35.0 ± 7.0 and 109.0 ± 5.0 μg per lens in the eye model. Moxifloxacin release ranged from 24.0 ± 4.0 to 226.0 ± 2.0 μg per lens for the vial, and between 13.0 ± 2.0 and 151.0 ± 10.0 μg per lens in the eye model. In both systems and for both drugs, HEMA-based CLs released more drugs than other materials. Conclusions.: The parameters of the release system, in particular the volume and flow rate, have a significant influence on measured release profiles. Under physiological flow, release profiles are significantly slower and constant when compared with release in a vial

    The Pragmatist in Context of a National Science Foundation Supported Grant Program Evaluation: Guidelines and Paradigms

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    Background:  The philosophical underpinnings of evaluation guidelines set forth by a funding agency can sometimes seem inconsistent with that of the intervention. Purpose: Our purpose is to introduce questions pertaining to the contrast between the instructional program’s underlying philosophical beliefs and assumptions and those underlying our evaluation approach. Drawing heavily on Scriven, we discuss these from a pragmatist evaluation stance in light of issues defined by Lincoln and Guba (2000). The discussion is couched in the evaluation of an innovative approach to teaching computer science. Setting: Auburn University, Auburn, AL Intervention: The evaluation is designed to investigate the effects of a studio-based teaching approach in computer science education. The evaluation framework employs a rigorous design that seeks to provide evidence to support or refute some assumed truth about the object (or construct) investigated. The program evaluated is steeped in a constructivist framework which assumes that no universal truth or reality exists, but rather, is constructed by the individual. Research Design: Our evaluation design, to a good extent, reflects a post-positivist, quasi-experimental position. We also include a qualitative component using student interviews. Data Collection and Analysis: Evidence of the effectiveness of the instructional approach for learning is assessed quantitatively using pre- and post-test and pre- and post-survey data group comparisons (mixed design ANOVA). Interviews provide the basis for qualitative theme analysis. Findings: Quantitative results were somewhat weak but consistent in support of the studio-based teaching. Interview data suggest that most students did find working in groups enjoyable and a valuable experience

    Release of Moxifloxacin from Contact Lenses Using an In Vitro Eye Model: Impact of Artificial Tear Fluid Composition and Mechanical Rubbing

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    Phan, C.-M., Bajgrowicz-Cieslak, M., Subbaraman, L. N., & Jones, L. (2016). Release of Moxifloxacin from Contact Lenses Using an In Vitro Eye Model: Impact of Artificial Tear Fluid Composition and Mechanical Rubbing. Translational Vision Science & Technology, 5(6), 3. https://doi.org/10.1167/tvst.5.6.3Purpose: The aim of this study was to evaluate and compare the release of moxifloxacin from a variety of daily disposable (DD) contact lenses (CLs) under various conditions using a novel in vitro eye model. Methods: Four commercially available DD conventional hydrogel (CH) CLs (nelfilcon A, omafilcon A, etafilcon A, and ocufilcon B) and three silicone hydrogel (SH) CLs (somofilcon A, narafilcon A, and delefilcon A) were evaluated. These lenses were incubated in moxifloxacin for 24 hours. The release of the drug was measured using a novel in vitro model in three experimental conditions: (1) phosphate buffered saline (PBS); (2) artificial tear solution (ATS) containing a variety of proteins and lipids; and (3) ATS with mechanical rubbing produced by the device. Results: Overall, CH CLs had a higher drug release than SH CLs (P < 0.05) under all conditions. Typically, a higher drug release was observed in PBS than ATS (P < 0.05). For CH, drug release was found to be higher in ATS with rubbing than PBS or ATS (P < 0.05). For most lens types, ATS with rubbing produced higher drug release than ATS alone (P < 0.05). Generally, the release kinetics for all conditions were sustained over the 24-hour testing period, and no burst release was observed (P < 0.05). Conclusions: Moxifloxacin release from a CL into ATS is lower when compared to release into PBS. When mechanical rubbing is introduced, the amount of drugs released is increased. Translational Relevance: Results suggest that sophisticated in vitro models are necessary to adequately model on-eye drug release from CL materials

    Insights to Using Contact Lenses for Drug Delivery

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    Phan, C.-M. (2013). Insights to Using Contact Lenses for Drug Delivery. Clinical & Experimental Pharmacology, 04(01). https://doi.org/10.4172/2161-1459.1000145There has been considerable interest in the potential application of contact lenses for ocular drug delivery. This short communication provides an overview of the challenges faced by delivering drugs using contact lenses, highlights the solutions to limitations that have already been achieved, and describes the barriers that remain before commercial application can be realized.NSERC 20/20 Network for the Development of Advanced Ophthalmic Material

    2,3,6-Triphenyl­piperidin-4-one

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    In the title mol­ecule, C23H21NO, the piperidine ring adopts a chair conformation, with the N and carbonyl C atoms as flaps, which deviate on either side of the chair by −0.706 (3) and 0.494 (3) Å, respectively. All three phenyl rings are in equatorial positions on the piperidine ring, making angles with the puckering plane of 73.5 (1), 73.1 (1) and 67.2 (1)°. Though there is no classical hydrogen bonding, the crystal is stabilized by inter­molecular C—H⋯π contacts and π–π stacking inter­actions involving phenyl rings [centroid–centroid distance = 4.424 (2) Å]

    Development of an In Vitro Ocular Platform to Test Contact Lenses

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    The definitive version of Development of an in Vitro Ocular Platform to Test Contact Lenses was published by Emerald www.emeraldinsight.com in Journal of Visualized Experiments, (110) (2016) https://doi.org/10.3791/53907Currently, in vitro evaluations of contact lenses (CLs) for drug delivery are typically performed in large volume vials,1-6 which fail to mimic physiological tear volumes.7 The traditional model also lacks the natural tear flow component and the blinking reflex, both of which are defining factors of the ocular environment. The development of a novel model is described in this study, which consists of a unique 2-piece design, eyeball and eyelid piece, capable of mimicking physiological tear volume. The models are created from 3-D printed molds (Polytetrafluoroethylene or Teflon molds), which can be used to generate eye models from various polymers, such as polydimethylsiloxane (PDMS) and agar. Further modifications to the eye pieces, such as the integration of an explanted human or animal cornea or human corneal construct, will permit for more complex in vitro ocular studies. A commercial microfluidic syringe pump is integrated with the platform to emulate physiological tear secretion. Air exposure and mechanical wear are achieved using two mechanical actuators, of which one moves the eyelid piece laterally, and the other moves the eyeballeyepiece circularly. The model has been used to evaluate CLs for drug delivery and deposition of tear components on CLs
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