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Search Results: 1 - 10 of 6017 matches for " Johnathan Williams "
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Design and Implementation of a Multi-Sensor Based Object Detecting and Removing Autonomous Robot Exploration System  [PDF]
Fan Wu, Johnathan Williams
Journal of Computer and Communications (JCC) , 2014, DOI: 10.4236/jcc.2014.27002
Abstract:

Developing autonomous mobile robot system has been a hot topic in AI area. With recent advances in technology, autonomous robots are attracting more and more attention worldwide, and there are a lot of ongoing research and development activities in both industry and academia. In complex ground environment, obstacles positions are uncertain. Path finding for robots in such environment is very hot issues currently. In this paper, we present the design and implementation of a multi-sensor based object detecting and moving autonomous robot exploration system, 4RE, with the VEX robotics design system. With the goals of object detecting and removing in complex ground environment with different obstacles, a novel object detecting and removing algorithms is proposed and implemented. Experimental results indicate that our robot system with our object detecting and removing algorithm can effectively detect the obstacles on the path and remove them in complex ground environment and avoid collision with the obstacles.

Impossible Airway Requiring Venovenous Bypass for Tracheostomy
Johnathan Gardes,Tracey Straker
Case Reports in Anesthesiology , 2012, DOI: 10.1155/2012/592198
Abstract: The elective surgical airway is the definitive management for a tracheal stenotic lesion that is not a candidate for tracheal resection, or who has failed multiple-tracheal dilations. This case report details the management of a patient who has failed an elective awake tracheostomy secondary to the inability to be intubated as well as severe scar tissue at the surgical site. A combination of regional anesthesia and venovenous bypass is used to facilitate the surgical airway management of this patient. Cerebral oximetry and a multidisciplinary team approach aid in early detection of an oxygenation issue, as well as the emergent intervention that preserved this patient’s life.
Impossible Airway Requiring Venovenous Bypass for Tracheostomy
Johnathan Gardes,Tracey Straker
Case Reports in Anesthesiology , 2012, DOI: 10.1155/2012/592198
Abstract: The elective surgical airway is the definitive management for a tracheal stenotic lesion that is not a candidate for tracheal resection, or who has failed multiple-tracheal dilations. This case report details the management of a patient who has failed an elective awake tracheostomy secondary to the inability to be intubated as well as severe scar tissue at the surgical site. A combination of regional anesthesia and venovenous bypass is used to facilitate the surgical airway management of this patient. Cerebral oximetry and a multidisciplinary team approach aid in early detection of an oxygenation issue, as well as the emergent intervention that preserved this patient’s life. 1. Introduction Proper management of the difficult airway presents one of the most important skill sets for the anesthesiologist to master. However, certain situations necessitate one look beyond traditional algorithms. In this case, a multidisciplinary team of otorhinolaryngologists, cardiac surgeons, perfusionists, and anesthesiologists decided to use venovenous bypass as a means to oxygenate a patient whose airway could not be secured because of severe tracheal stenosis. 2. Case Report A 45-year-old woman with a long history of tracheal stenosis and upper airway obstruction presented for elective tracheostomy placement in the setting of supra- and infraglottic stenosis after failed awake tracheostomy by an otorhinolaryngologist (ORL) (Figures 1 and 2). It was felt by the attending ORL surgeon that the airway could not be secured from above after serial diagnostic scopes. Due to the failed awake tracheostomy, it was felt that surgical airway under bypass was the only option. Figure 1: CT SCAN of subglottic tracheal stenosis. Figure 2: CT SCAN of tracheal diameter. Eight years previously, the patient presented for an elective bilateral tubal ligation. At the time, she was otherwise healthy. The intraoperative course was unremarkable and the patient’s trachea was extubated on the operating table. However, after moving to the stretcher for transport, she developed acute respiratory distress. She was quickly returned to the operating room (OR) table and her trachea reintubated after several attempts at direct laryngoscopy. At the time, her airway was noted to be acutely swollen and edematous. She remained intubated in the intensive care unit for two weeks during which time several attempts at extubation failed. Finally, she was weaned off support and discharged home. The presumptive diagnosis was an acute allergic reaction to the antibiotic cephazolamine, which she had received
Plasma-Etching of the Organic Layer in Nacre  [PDF]
Kirsten Parratt, Johnathan M. Yao, Gerald R. Poirier, Nan Yao
Soft Nanoscience Letters (SNL) , 2014, DOI: 10.4236/snl.2014.43009
Abstract:

Nacre’s brick and mortar structure has been motivating innovations in biomimetic materials for decades. However, there is still room to improve understanding of the structure of the organic layer in order to engineer better biomimetic composites. A plasma-etching technique that allows for the selective removal of some organic components from individual layers is developed. We conclude that this technique enables a closer examination of the organic layer such that the locations and mechanical properties of individual components can be determined. A methodology for examining nacre samples that have not been demineralized provides a more accurate substrate for understanding the structure-property relationships of the organic layer in native nacre.

fog-2 and the Evolution of Self-Fertile Hermaphroditism in Caenorhabditis
Sudhir Nayak,Johnathan Goree,Tim Schedl
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0030006
Abstract: Somatic and germline sex determination pathways have diverged significantly in animals, making comparisons between taxa difficult. To overcome this difficulty, we compared the genes in the germline sex determination pathways of Caenorhabditis elegans and C. briggsae, two Caenorhabditis species with similar reproductive systems and sequenced genomes. We demonstrate that C. briggsae has orthologs of all known C. elegans sex determination genes with one exception: fog-2. Hermaphroditic nematodes are essentially females that produce sperm early in life, which they use for self fertilization. In C. elegans, this brief period of spermatogenesis requires FOG-2 and the RNA-binding protein GLD-1, which together repress translation of the tra-2 mRNA. FOG-2 is part of a large C. elegans FOG-2-related protein family defined by the presence of an F-box and Duf38/FOG-2 homogy domain. A fog-2-related gene family is also present in C. briggsae, however, the branch containing fog-2 appears to have arisen relatively recently in C. elegans, post-speciation. The C-terminus of FOG-2 is rapidly evolving, is required for GLD-1 interaction, and is likely critical for the role of FOG-2 in sex determination. In addition, C. briggsae gld-1 appears to play the opposite role in sex determination (promoting the female fate) while maintaining conserved roles in meiotic progression during oogenesis. Our data indicate that the regulation of the hermaphrodite germline sex determination pathway at the level of FOG-2/GLD-1/tra-2 mRNA is fundamentally different between C. elegans and C. briggsae, providing functional evidence in support of the independent evolution of self-fertile hermaphroditism. We speculate on the convergent evolution of hermaphroditism in Caenorhabditis based on the plasticity of the C. elegans germline sex determination cascade, in which multiple mutant paths yield self fertility.
Response to dexamethasone is glucose-sensitive in multiple myeloma cell lines
Ellen Friday, Johnathan Ledet, Francesco Turturro
Journal of Experimental & Clinical Cancer Research , 2011, DOI: 10.1186/1756-9966-30-81
Abstract: Multiple myeloma (MM) cells were grown in 5 or 20 mM/L glucose with or without 25 μM DEX. Semiquantitative reverse transcription-PCR (RT-PCR) was used to assess TXNIP RNA expression in response to glucose and DEX. ROS were detected by 5-6-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-H2DCFDA). TRX activity was assayed by the insulin disulfide-reducing assay. Proliferation was evaluated using CellTiter96 reagent with 490-nm absorbtion and used to calculate the DEX IC50 in 20 mM/L glucose using the Chou's dose effect equation.TXNIP RNA level responded to glucose or DEX with the same order of magnitude ARH77 > NCIH929 > U266B1 in these cells. MC/CAR cells were resistant to the regulation. ROS level increased concurrently with reduced TRX activity. Surprisingly glucose increased TRX activity in MC/CAR cells keeping ROS level low. DEX and glucose were lacking the expected additive effect on TXNIP RNA regulation when used concurrently in sensitive cells. ROS level was significantly lower when DEX was used in conditions of hyperglycemia in ARH77/NCIH9292 cells but not in U266B1 cells. Dex-IC50 increased 10-fold when the dose response effect of DEX was evaluated with glucose in ARH && and MC/Car cellsOur study shows for the first time that glucose or DEX regulates important components of ROS production through TXNIP modulation or direct interference with TRX activity in MM cells. We show that glucose modulates the activity of DEX through ROS regualtion in MM cells. A better understanding of these pathways may help in improving the efficacy and reducing the toxicity of DEX, a drug still highly used in the treatment of MM. Our study also set the ground to study the relevance of the metabolic milieu in affecting drug response and toxicity in diabetic versus non-diabetic patients with MM.Despite the booming of novel agents for the treatment of multiple myeloma (MM) such as proteasome inhibitor bortezomib, and immuno-modulator agents thalidomide or lenalidomide, de
SHORT COMMUNICATION ON THE INFLUENCE OF POSITION ON ANTERIOR CRUCIATE LIGAMENT INJURY AND RECONSTRUCTION IN RECREATIONAL RUGBY FOOTBALL UNION PARTICIPANTS
Johnathan Collett,Helen Dawes,Richard P. Craven
Journal of Sports Science and Medicine , 2003,
Abstract: The different player positions in rugby union may place varying demands on a reconstructed anterior cruciate ligament (ACL) in regards to 'cutting manoeuvres', this in turn may effect performance. In order to investigate sporting performance post reconstruction, a questionnaire was sent to amateur rugby clubs affiliated to the Oxfordshire Rugby Football Union (R.F.U). From the returned questionnaires player positions were placed into categories based on similar 'cutting manoeuvre' demands. Seventy five percent of Individuals playing in the category 1 (low 'cutting manoeuvre' demands at slow running speeds) could play a full game with a damaged ACL and post-reconstruction the majority returned to play at a higher level. Fifty percent of ACL injuries occurred on category 2 (high 'cutting manoeuvre' demands at medium running speeds) suggesting they may be more prone to ACL injury than other positions. The majority of individuals playing in category 3 (high 'cutting manoeuvre' demands at fast speeds) played at a lower level of rugby post reconstruction. Positional demands may influence ACL injury and post reconstruction sporting performance. However, more research is needed
fog-2 and the Evolution of Self-Fertile Hermaphroditism in Caenorhabditis
Sudhir Nayak,Johnathan Goree,Tim Schedl
PLOS Biology , 2005, DOI: 10.1371/journal.pbio.0030006
Abstract: Somatic and germline sex determination pathways have diverged significantly in animals, making comparisons between taxa difficult. To overcome this difficulty, we compared the genes in the germline sex determination pathways of Caenorhabditis elegans and C. briggsae, two Caenorhabditis species with similar reproductive systems and sequenced genomes. We demonstrate that C. briggsae has orthologs of all known C. elegans sex determination genes with one exception: fog-2. Hermaphroditic nematodes are essentially females that produce sperm early in life, which they use for self fertilization. In C. elegans, this brief period of spermatogenesis requires FOG-2 and the RNA-binding protein GLD-1, which together repress translation of the tra-2 mRNA. FOG-2 is part of a large C. elegans FOG-2-related protein family defined by the presence of an F-box and Duf38/FOG-2 homogy domain. A fog-2-related gene family is also present in C. briggsae, however, the branch containing fog-2 appears to have arisen relatively recently in C. elegans, post-speciation. The C-terminus of FOG-2 is rapidly evolving, is required for GLD-1 interaction, and is likely critical for the role of FOG-2 in sex determination. In addition, C. briggsae gld-1 appears to play the opposite role in sex determination (promoting the female fate) while maintaining conserved roles in meiotic progression during oogenesis. Our data indicate that the regulation of the hermaphrodite germline sex determination pathway at the level of FOG-2/GLD-1/tra-2 mRNA is fundamentally different between C. elegans and C. briggsae, providing functional evidence in support of the independent evolution of self-fertile hermaphroditism. We speculate on the convergent evolution of hermaphroditism in Caenorhabditis based on the plasticity of the C. elegans germline sex determination cascade, in which multiple mutant paths yield self fertility.
Identification and Functional Characterization of Genes Encoding Omega-3 Polyunsaturated Fatty Acid Biosynthetic Activities from Unicellular Microalgae
Royah Vaezi,Johnathan A. Napier,Olga Sayanova
Marine Drugs , 2013, DOI: 10.3390/md11125116
Abstract: In order to identify novel genes encoding enzymes involved in the biosynthesis of nutritionally important omega-3 long chain polyunsaturated fatty acids, a database search was carried out in the genomes of the unicellular photoautotrophic green alga Ostreococcus RCC809 and cold-water diatom Fragilariopsis cylindrus. The search led to the identification of two putative “front-end” desaturases (Δ6 and Δ4) from Ostreococcus RCC809 and one Δ6-elongase from F. cylindrus. Heterologous expression of putative open reading frames (ORFs) in yeast revealed that the encoded enzyme activities efficiently convert their respective substrates: 54.1% conversion of α-linolenic acid for Δ6-desaturase, 15.1% conversion of 22:5 n-3 for Δ4-desaturase and 38.1% conversion of γ-linolenic acid for Δ6-elongase. The Δ6-desaturase from Ostreococcus RCC809 displays a very strong substrate preference resulting in the predominant synthesis of stearidonic acid (C18:4Δ 6,9,12,15). These data confirm the functional characterization of omega-3 long chain polyunsaturated fatty acid biosynthetic genes from these two species which have until now not been investigated for such activities. The identification of these new genes will also serve to expand the repertoire of activities available for metabolically engineering the omega-3 trait in heterologous hosts as well as providing better insights into the synthesis of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in marine microalgae.
The stress-pressure relationship in simulations of MRI-induced turbulence
Johnathan Ross,Henrik N. Latter,Jerome Guilet
Physics , 2015, DOI: 10.1093/mnras/stv2286
Abstract: We determine how MRI-turbulent stresses depend on gas pressure via a suite of unstratified shearing box simulations. Earlier numerical work reported only a very weak dependence at best, results that call into question the canonical alpha-disk model and the thermal stability results that follow from it. Our simulations, in contrast, exhibit a stronger relationship, and show that previous work was box-size limited: turbulent `eddies' were artificially restricted by the numerical domain rather than by the scale height. Zero-net-flux runs without physical diffusion coefficients yield a stress proportional to $P^{0.5}$, where P is pressure. The stresses are also proportional to the grid length and hence remain numerically unconverged. The same runs with physical diffusivities, however, give a result closer to an alpha-disk: the stress is proportional to $P^{0.9}$. Net-flux simulations without explicit diffusion exhibit stresses proportional to $P^{0.5}$, but stronger imposed fields weaken this correlation. In summary, compressibility is important for the saturation of the MRI, but the exact stress-pressure relationship is difficult to ascertain in local simulations because of numerical convergence issues and the influence of any imposed flux. As a consequence, the interpretation of thermal stability behaviour in local simulations is a problematic enterprise.
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