39 results on '"David A. Mitchell"'
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2. Closed magnetic topology in the Venusian magnetotail and ion escape at Venus
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Shaosui Xu, David L. Mitchell, Phyllis Whittlesey, Ali Rahmati, Roberto Livi, Davin Larson, Janet G. Luhmann, Jasper S. Halekas, Takuya Hara, James P. McFadden, Marc Pulupa, Stuart D. Bale, Shannon M. Curry, and Moa Persson
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Science - Abstract
Abstract Venus, lacking an intrinsic global dipole magnetic field, serves as a textbook example of an induced magnetosphere, formed by interplanetary magnetic fields (IMF) enveloping the planet. Yet, various aspects of its magnetospheric dynamics and planetary ion outflows are complex and not well understood. Here we analyze plasma and magnetic field data acquired during the fourth Venus flyby of the Parker Solar Probe (PSP) mission and show evidence for closed topology in the nightside and downstream portion of the Venus magnetosphere (i.e., the magnetotail). The formation of the closed topology involves magnetic reconnection—a process rarely observed at non-magnetized planets. In addition, our study provides an evidence linking the cold Venusian ion flow in the magnetotail directly to magnetic connectivity to the ionosphere, akin to observations at Mars. These findings not only help the understanding of the complex ion flow patterns at Venus but also suggest that magnetic topology is one piece of key information for resolving ion escape mechanisms and thus the atmospheric evolution across various planetary environments and exoplanets.
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- 2024
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3. Work Where You Live or Live Where You Work? Resident Work and Sleep Patterns While on 'Home Call'
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David T. Mitchell, MD, Noa G. Koppin, BS, Michael T. Talanker, BS, Mohin A. Bhadkamkar, MD, Erik S. Marques, MD, Matthew R. Greives, MD, and David C. Hopkins, MD
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Surgery ,RD1-811 - Abstract
Background:. Unlike in-house call, the Accreditation Council for Graduate Medical Education (ACGME) does not require a postcall day for “home call” shifts. Despite this, we hypothesize that on-call residents are still in the hospital for the majority of their shift despite having the luxury of home call and, thus, are not protected by ACGME postcall duty hour regulations. Methods:. A prospective single center survey study was conducted by surveying junior and senior residents who completed overnight call shifts from January 2023 to April 2023 at one of the busiest level 1 trauma centers in the United States. Data include number of trips into the hospital, hours spent in the hospital, and hours of sleep. Results:. Response rate was 195 of 200 (97.5%) total call shifts from 7 pm to 7 am the next morning. Junior residents reported an average of 3.25, 3.92, and 0.73 hours of sleep when on hand call, face call, and triple call (hand + face + general), respectively. Senior residents reported an average of 4.18 and 4.75 hours of sleep for hand and face call, respectively. Conclusions:. Hours of sleep when taking home call varies widely based on type of call. Junior residents reported significantly decreased sleep and more time in the hospital when taking hand, face, and triple call compared with general call alone. Senior residents reported that both hand and face call result in significantly decreased hours of sleep compared with general call alone. These results highlight the need to discuss ACGME protection for residents taking home call.
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- 2024
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4. Thematic review series: Lipid Posttranslational Modifications. Protein palmitoylation by a family of DHHC protein S-acyltransferases
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David A. Mitchell, Anant Vasudevan, Maurine E. Linder, and Robert J. Deschenes
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fatty acylation ,cysteine rich domain ,palmitoyl-CoenzymeA ,Biochemistry ,QD415-436 - Abstract
Protein palmitoylation refers to the posttranslational addition of a 16 carbon fatty acid to the side chain of cysteine, forming a thioester linkage. This acyl modification is readily reversible, providing a potential regulatory mechanism to mediate protein-membrane interactions and subcellular trafficking of proteins. The mechanism that underlies the transfer of palmitate or other long-chain fatty acids to protein was uncovered through genetic screens in yeast. Two related S-palmitoyltransferases were discovered. Erf2 palmitoylates yeast Ras proteins, whereas Akr1 modifies the yeast casein kinase, Yck2. Erf2 and Akr1 share a common sequence referred to as a DHHC (aspartate-histidine-histidine-cysteine) domain. Numerous genes encoding DHHC domain proteins are found in all eukaryotic genome databases. Mounting evidence is consistent with this signature motif playing a direct role in protein acyltransferase (PAT) reactions, although many questions remain. This review presents the genetic and biochemical evidence for the PAT activity of DHHC proteins and discusses the mechanism of protein-mediated palmitoylation.
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- 2006
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5. Effect of Nitrogen and Carbon Sources on Lipase Production by Penicillium aurantiogriseum
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Valéria M. G. Lima, Nadia Krieger, Maria Inez M. Sarquis, David A. Mitchell, Luiz P. Ramos, and José D. Fontana
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lipases ,Penicillium aurantiogriseum ,media optimization ,lipolytic activity ,inorganic nitrogen sources ,Biotechnology ,TP248.13-248.65 ,Food processing and manufacture ,TP368-456 - Abstract
A wild fungal strain isolated from soybean oil and identified as Penicillium aurantiogriseum initially presented a volumetric lipase activity of 0.4 U/mL in submerged culture in a medium containing 0.5 % yeast extract and 1 % olive oil. Studies were undertaken to improve lipase production. The effect of nitrogen source was studied by adding casein peptone, meat peptone, yeast extract or ammonium sulfate to a medium containing potassium nitrate and other mineral salts. The best yield, of 13 U/mL after 72 h, was obtained with the medium supplemented with ammonium sulfate. With the ammonium sulfate concentration increased to double the C/N ratio from 2.5 to 5, a lipolytic activity of 18 U/mL was obtained. Olive, corn, soy and sunflower oils were tested as carbon sources in this medium, with olive oil at 1 % giving a lipolytic activity of 25 U/mL after 48 h, the highest yield obtained in this study. Enzyme production was best at 29 °C, within a range tested from 26 to 32 °C. These results are promising because this strain produces lipase in an inexpensive inorganic medium and we succeeded in increasing the lipolytic activity 62-fold over the initial values obtained with the non-optimized medium.
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- 2003
6. A Model for Converting Solid State Fermentation Growth Profiles Between Absolute and Relative Measurement Bases
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Nadia Krieger, Graciele Viccini, and David A. Mitchell
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solid-state fermentation ,microbial growth kinetics ,logistic equation ,exponential growth kinetics ,linear growth kinetics ,Biotechnology ,TP248.13-248.65 ,Food processing and manufacture ,TP368-456 - Abstract
A mathematical model is developed for converting between the two measurement bases commonly used in the construction of growth profiles in solid-state fermentation, namely absolute mass ratio m(dry biomass)/m(initial dry matter) and relative mass ratio m(dry biomass)/m(dry matter). These are not equivalent, due to the loss of dry matter as CO2 during the fermentation. The model is equally applicable to any biomass component used in indirect measurements of growth, such as protein. Use of the model to convert absolute mass ratio of the biomass profiles for the growth of Rhizopus oligosporus to a relative basis gave profiles that agreed well with the experimentally determined relative biomass profiles. This agreement was obtained for three different fermentations using the same set of parameter values in the model, namely a yield coefficient of m(protein)/m(dry substrate) = 0.2 g/g and a maintenance coefficient of zero, giving confidence in the reliability of the model. The model was then used to show that the measurement basis used can affect the form of the curve and therefore can also affect the conclusion drawn about the type of kinetics shown by the organism, with the extent of this effect depending on the length of time that growth occurs and the values of the yield and maintenance coefficients. This work shows that great care must be taken in drawing conclusions about growth kinetics in solid-state fermentation.
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- 2003
7. A Model for Converting Solid State Fermentation Growth Profiles Between Absolute and Relative Measurement Bases
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Graciele Viccini, Nadia Krieger, and David A. Mitchell
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solid-state fermentation ,microbial growth kinetics ,logistic equation ,exponential growth kinetics ,linear growth kinetics ,Biotechnology ,TP248.13-248.65 ,Food processing and manufacture ,TP368-456 - Abstract
A mathematical model is developed for converting between the two measurement bases commonly used in the construction of growth profiles in solid-state fermentation, namely absolute mass ratio m(dry biomass)/m(initial dry matter) and relative mass ratio m(dry biomass)/m(dry matter). These are not equivalent, due to the loss of dry matter as CO2 during the fermentation. The model is equally applicable to any biomass component used in indirect measurements of growth, such as protein. Use of the model to convert absolute mass ratio of the biomass profiles for the growth of Rhizopus oligosporus to a relative basis gave profiles that agreed well with the experimentally determined relative biomass profiles. This agreement was obtained for three different fermentations using the same set of parameter values in the model, namely a yield coefficient of m(protein)/m(dry substrate) = 0.2 g/g and a maintenance coefficient of zero, giving confidence in the reliability of the model. The model was then used to show that the measurement basis used can affect the form of the curve and therefore can also affect the conclusion drawn about the type of kinetics shown by the organism, with the extent of this effect depending on the length of time that growth occurs and the values of the yield and maintenance coefficients. This work shows that great care must be taken in drawing conclusions about growth kinetics in solid-state fermentation.
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- 2003
8. Evaluation of Productivity of Zymotis Solid-State Bioreactor Based on Total Reactor Volume
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Oscar F. von Meien, Luiz Fernando L. Luz Jr, Nadia Krieger, and David A. Mitchell
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Zymotis bioreactor ,volumetric productivity ,solid-state fermentation ,modeling ,large scale cultivation ,heat transfer ,Biotechnology ,TP248.13-248.65 ,Food processing and manufacture ,TP368-456 - Abstract
In this work a method of analyzing the performance of solid-state fermentation bioreactors is described. The method is used to investigate the optimal value for the spacing between the cooling plates of the Zymotis bioreactor, using simulated fermentation data supplied by a mathematical model. The Zymotis bioreactor has good potential for those solid-state fermentation processes in which the substrate bed must remain static. The current work addresses two design parameters introduced by the presence of the internal heat transfer plates: the width of the heat transfer plate, which is governed by the amount of heat to be removed and the pressure drop of the cooling water, and the spacing between these heat transfer plates. In order to analyze the performance of the bioreactor a productivity term is introduced that takes into account the volume occupied within the bioreactor by the heat transfer plates. As part of this analysis, it is shown that, for logistic growth kinetics, the time at which the biomass reaches 90 % of its maximum possible value is a good estimate of the optimum harvesting time for maximizing productivity. Application of the productivity analysis to the simulated fermentation results suggests that, with typical fast growing fungi ( = 0.324 h–1), the optimal spacing between heat transfer plates is of the order of 6 cm. The general applicability of this approach to evaluate the productivity of solid-state bioreactors is demonstrated.
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- 2002
9. Schwannomas of the head and neck
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Anastasios Kanatas, Thomas Mucke, David Houghton, and David A. Mitchell
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Schwannomas - Benign tumors - Head and neck tumors ,Other systems of medicine ,RZ201-999 ,Internal medicine ,RC31-1245 - Abstract
Schwannomas are benign encapsulated nerve sheath tumors composed of Schwann cells. Malignant change in head and neck schwannomas is rare, with the incidence varying between 8 and 13.9%. In this review, we discuss the presentation and the management of head and neck schwannomas. The issues and difficulties based on our own experience as well as the experience of published reports from the literature are presented.
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- 2011
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10. Martian Bow Shock Oscillations Driven by Solar Wind Variations: Simultaneous Observations From Tianwen‐1 and MAVEN
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Long Cheng, Robert Lillis, Yuming Wang, Anna Mittelholz, Shaosui Xu, David L. Mitchell, Catherine Johnson, Zhenpeng Su, Jasper S. Halekas, Benoit Langlais, Tielong Zhang, Guoqiang Wang, Sudong Xiao, Zhuxuan Zou, Zhiyong Wu, Yutian Chi, Zonghao Pan, Kai Liu, Xinjun Hao, Yiren Li, Manming Chen, Jared Espley, Frank Eparvier, and Shannon Curry
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Geophysics. Cosmic physics ,QC801-809 - Abstract
Abstract The Martian bow shock stands as the first defense against the solar wind and shapes the Martian magnetosphere. Previous studies showed the correlation between the Martian bow shock location and solar wind parameters. Here we present direct evidence of solar wind effects on the Martian bow shock by analyzing Tianwen‐1 and MAVEN data. We examined three cases where Tianwen‐1 data show rapid oscillations of the bow shock, while MAVEN data record changes in solar wind plasma and magnetic field. The results indicate that the bow shock is rapidly compressed and then expanded during the dynamic pressure pulse in the solar wind, and is also oscillated during the IMF rotation. The superposition of variations in multiple solar wind parameters leads to more intensive bow shock oscillation. This study emphasizes the importance of joint observations by Tianwen‐1 and MAVEN for studying the real‐time response of the Martian magnetosphere to the solar wind.
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- 2023
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11. Source of Drift-dispersed Electrons in Martian Crustal Magnetic Fields
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Chi Zhang, Hongyang Zhou, Chuanfei Dong, Yuki Harada, Masatoshi Yamauchi, Shaosui Xu, Hans Nilsson, Yusuke Ebihara, Shannon M. Curry, Junfeng Qin, David L. Mitchell, and David A. Brain
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Mars ,Magnetic fields ,Solar wind ,Astrophysics ,QB460-466 - Abstract
Mars lacks a global intrinsic dipole field but possesses localized crustal fields, making it unique in the solar system. Recent observations revealed that electrons can be injected into the crustal fields, and exhibit drift-dispersed bursts due to the magnetic drift motion, which are characterized by increases or decreases in energy over time in the energy spectrum. However, the source of the drift-dispersed electrons and the mechanism of their injection into the crustal fields remains unclear. Here, by leveraging data from the Mars Atmosphere and Volatile EvolutioN mission, along with test-particle simulations, we reveal that the source of dispersed electrons is the precipitating electrons injected into the crustal fields via open field lines. These electrons display as dispersionless bursts near the source location, and as dispersed bursts as they drift away from the source. Thus, the dispersed electrons represent a later stage in the evolution of dispersionless electrons. This evolutionary process closely mirrors that observed within Earth’s dipole field, affirming that the crustal fields function similarly to a mini-magnetosphere.
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- 2024
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12. Electrically Small Sleeve Baluns Constructed Using Additive Manufacturing
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David S. Mitchell and Jessica E. Ruyle
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Additive manufacturing ,3D printing ,baluns ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
This paper documents a novel method for the design and construction of unfolded, folded, and dielectrically-loaded sleeve baluns using additive manufacturing to achieve an electrically small form factor for size and weight constrained applications. Single and double-folded sleeve baluns were constructed, tested, and compared to standard sleeve baluns. The baluns decreased 40% in size with each successive folding, with the smallest air-core baluns being 36% the size of a standard sleeve balun. Dielectric-loading was utilized to further miniaturize, resulting in a balun that is only 21% the size of a standard sleeve balun. The double-folded balun constructed using additive manufacturing is also only 40% of the weight of a standard sleeve balun. The Common Mode Rejection Ratio (CMRR) was above 38 dB for all baluns. These baluns achieve a small form factor, similar to ferrite beads, making them usable as inline components in systems where traditional sleeve baluns are too large and heavy.
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- 2022
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13. The process of replication target selection in psychology: what to consider?
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Merle-Marie Pittelkow, Sarahanne M. Field, Peder M. Isager, Anna E. van’t Veer, Thomas Anderson, Scott N. Cole, Tomáš Dominik, Roger Giner-Sorolla, Sebahat Gok, Tom Heyman, Marc Jekel, Timothy J. Luke, David B. Mitchell, Rik Peels, Rosina Pendrous, Samuel Sarrazin, Jacob M. Schauer, Eva Specker, Ulrich S. Tran, Marek A. Vranka, Jelte M. Wicherts, Naoto Yoshimura, Rolf A. Zwaan, and Don van Ravenzwaaij
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replication ,study selection ,consensus ,Science - Abstract
Increased execution of replication studies contributes to the effort to restore credibility of empirical research. However, a second generation of problems arises: the number of potential replication targets is at a serious mismatch with available resources. Given limited resources, replication target selection should be well-justified, systematic and transparently communicated. At present the discussion on what to consider when selecting a replication target is limited to theoretical discussion, self-reported justifications and a few formalized suggestions. In this Registered Report, we proposed a study involving the scientific community to create a list of considerations for consultation when selecting a replication target in psychology. We employed a modified Delphi approach. First, we constructed a preliminary list of considerations. Second, we surveyed psychologists who previously selected a replication target with regards to their considerations. Third, we incorporated the results into the preliminary list of considerations and sent the updated list to a group of individuals knowledgeable about concerns regarding replication target selection. Over the course of several rounds, we established consensus regarding what to consider when selecting a replication target. The resulting checklist can be used for transparently communicating the rationale for selecting studies for replication.
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- 2023
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14. Open Magnetic Fields in the Martian Magnetosphere Revealing Dipole-like Intrinsic Magnetic Fields at Mars
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Shaosui Xu, Janet G. Luhmann, David L. Mitchell, Tristan Weber, David A. Brain, Yingjuan Ma, Shannon M. Curry, Gina A. DiBraccio, Jasper Halekas, Suranga Ruhunusiri, Christian Mazelle, Robert J. Lillis, and Benoit Langlais
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Mars ,Solar-planetary interactions ,Magnetic fields ,Interplanetary magnetic fields ,Magnetic anomalies ,Astrophysics ,QB460-466 - Abstract
Mars’s magnetosphere is hybrid, having contributions from both an induced magnetosphere like Venus and the localized crustal magnetic fields. However, the planetary fields also include large-scale, more global components. In this study, we investigate their role in Mars’s magnetospheric topological responses to the interplanetary magnetic field (IMF) clock angle using observations from the Mars Atmospheric Volatile and EvolutioN mission. We show that the large-scale planetary field has a “dipole-like” influence on the Mars global magnetosphere by examining the open field topology. We find that the “dipole-like” planetary field, as at Earth, results in a more open magnetosphere during southward IMF. The clock angle effects on the twisted magnetotail current sheet are similarly consistent with this analogy. It reinforces the idea that Mars’s magnetosphere and solar wind interaction are more Earth-like than previously thought.
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- 2023
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15. Disability Ghosting in the Double Lockdown Institution of COVID-19
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David Thomas Mitchell
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disability ,journalistic representation ,COVID-19 ,ghosting disability ,viral journalism ,Social sciences (General) ,H1-99 - Abstract
This paper surveys some of the voluminous journalistic coverage of the COVID-19 pandemic and the public health responses that ensued. While investigative reporting in newspapers and news programming played an important function, we expose the terms of the underreporting about the lockdowns in institutions for the disabled and elderly that ultimately changed little about public knowledge of the lives of disabled people who were always or already confined. Second, we detail the rapid unfolding of a critical journalism that revealed the mortality-dealing conditions of institutionalization beyond the acceleration of pandemic risk levels. Such governmental and for-profit run practices of letting individuals who were disabled or elderly die while in their care were enacted, of which residents could do nothing to protect themselves (in fact, risky exposure was a conscious practice of state governments during the unfolding viral epidemic). This essay argues, however, that a critical branch of COVID-19 journalism (largely based in the US) used investigative reporting to expose governmental miscounting, undercounting, and neglecting-to-count of disability deaths due to COVID-19 and/or to collect them under “other categories,” such as the overall death rate of a population. Our key findings point out that despite the importance of this coverage, no one used this opportunity to talk with institutionalized disabled and/or elderly people—who were gravely at risk. Thus, we learned little about disabled peoples’ lives as they were shipped back to congregate care settings and institutions from hospitals without treatment. An opportunity to explain disability institutionalization and its inherent dangers were lost despite the media saturation of coverage that rose in the wake of COVID-19 public health policies and practices.
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- 2023
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16. Understanding the unexplained: The magnitude and correlates of individual differences in residual variance
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David J. Mitchell, Christa Beckmann, and Peter A. Biro
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animal personality ,behavioral plasticity ,behavioral predictability ,behavioral reaction norm ,intraindividual variability ,Ecology ,QH540-549.5 - Abstract
Abstract Behavioral and physiological ecologists have long been interested in explaining the causes and consequences of trait variation, with a focus on individual differences in mean values. However, the majority of phenotypic variation typically occurs within individuals, rather than among individuals (as indicated by average repeatability being less than 0.5). Recent studies have further shown that individuals can also differ in the magnitude of variation that is unexplained by individual variation or environmental factors (i.e., residual variation). The significance of residual variation, or why individuals differ, is largely unexplained, but is important from evolutionary, methodological, and statistical perspectives. Here, we broadly reviewed literature on individual variation in behavior and physiology, and located 39 datasets with sufficient repeated measures to evaluate individual differences in residual variance. We then analyzed these datasets using methods that permit direct comparisons of parameters across studies. This revealed substantial and widespread individual differences in residual variance. The magnitude of individual variation appeared larger in behavioral traits than in physiological traits, and heterogeneity was greater in more controlled situations. We discuss potential ecological and evolutionary implications of individual differences in residual variance and suggest productive future research directions.
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- 2021
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17. Safety, Tolerability, Pharmacokinetics, Target Occupancy, and Concentration‐QT Analysis of the Novel BTK Inhibitor Evobrutinib in Healthy Volunteers
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Andreas Becker, Emily C. Martin, David Y. Mitchell, Roland Grenningloh, Andrew T. Bender, Julien Laurent, Harald Mackenzie, and Andreas Johne
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Therapeutics. Pharmacology ,RM1-950 ,Public aspects of medicine ,RA1-1270 - Abstract
Bruton's tyrosine kinase (BTK) is a key regulator of B cell receptor and Fc receptor signaling, and a rational therapeutic target for autoimmune diseases. This first‐in‐human phase I, double‐blind, placebo‐controlled trial investigated the safety, tolerability, pharmacokinetics (PK), target occupancy, and effects on QT interval of evobrutinib, a highly selective, oral inhibitor of BTK, in healthy subjects. This dose escalation trial consisted of two parts. Part 1 included 48 subjects in 6 ascending dose cohorts (25, 50, 100, 200, 350, and 500 mg) randomized to a single dose of evobrutinib or placebo. Part 2 included 36 subjects in 3 ascending dose cohorts (25, 75, and 200 mg/day) randomized to evobrutinib or placebo once daily for 14 days. Safety and tolerability, as well as PK and target occupancy (total and free BTK in peripheral blood mononuclear cells), were assessed following single and multiple dosing. PK parameters were determined by noncompartmental methods. QT interval was obtained from 12‐lead electrocardiogram recordings and corrected for heart rate by Fridericia's method (QTcF). Treatment‐emergent adverse events (TEAEs) were mostly mild, occurring in 25% of subjects after single dosing, and 48.1% after multiple dosing. There was no apparent dose relationship regarding frequency or type of TEAE among evobrutinib‐treated subjects. Absorption was rapid (time to reach maximum plasma concentration (Tmax) ~ 0.5 hour), half‐life short (~ 2 hours), and PK dose‐proportional, with no accumulation or time dependency on repeat dosing. BTK occupancy was dose‐dependent, reaching maximum occupancy of > 90% within ~ 4 hours after single doses ≥ 200 mg; the effect was long‐lasting (> 50% occupancy at 96 hours with ≥ 100 mg). After multiple dosing, full BTK occupancy was achieved with 25 mg, indicating slow turnover of BTK protein in vivo. Concentration‐QTcF analyses did not show any impact of evobrutinib concentration on corrected QT (QTc). In summary, evobrutinib was well‐tolerated, showed linear and time‐independent PK, induced long‐lasting BTK inhibition, and was associated with no prolongation of QT/QTc interval in healthy subjects. Evobrutinib is, therefore, suitable for investigation in autoimmune diseases.
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- 2020
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18. Ultra-small cobalt particles embedded in titania by ion beam synthesis: Additional datasets including electron microscopy, neutron reflectometry, modelling outputs and particle size analysis
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Abdulhakim Bake, Md Rezoanur Rahman, Peter J. Evans, Michael Cortie, Mitchell Nancarrow, Radu Abrudan, Florin Radu, Yury Khaydukov, Grace Causer, Karen L. Livesey, Sara Callori, David R.G. Mitchell, Zeljko Pastuovic, Xiaolin Wang, and David Cortie
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Cobalt nanoclusters ,Ion implantation ,In-situ heat treatment ,Superparamagnetic ,Neutron spin asymmetry ,Computer applications to medicine. Medical informatics ,R858-859.7 ,Science (General) ,Q1-390 - Abstract
This Data-in-brief article includes datasets of electron microscopy, polarised neutron reflectometry and magnetometry for ultra-small cobalt particles formed in titania thin films via ion beam synthesis. Raw data for polarised neutron reflectometry, magnetometry and the particle size distribution are included and made available on a public repository. Additional elemental maps from scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) are also presented. Data were obtained using the following types of equipment: the NREX and PLATYPUS polarised neutron reflectometers; a Quantum Design Physical Property Measurement System (14 T); a JEOL JSM-6490LV SEM, and a JEOL ARM-200F scanning transmission electron microscope (STEM). The data is provided as supporting evidence for the article in Applied Surface Science (A. Bake et al., Appl. Surf. Sci., vol. 570, p. 151068, 2021, DOI 10.1016/j.apsusc.2021.151068), where a full discussion is given. The additional supplementary reflectometry and modelling datasets are intended to assist future scientific software development of advanced fitting algorithms for magnetization gradients in thin films.
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- 2022
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19. Additive Manufacturing of C/C-SiC Ceramic Matrix Composites by Automated Fiber Placement of Continuous Fiber Tow in Polymer with Pyrolysis and Reactive Silicon Melt Infiltration
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Corson L. Cramer, Bola Yoon, Michael J. Lance, Ercan Cakmak, Quinn A. Campbell, and David J. Mitchell
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3D printing ,ceramic matrix composites ,reactive melt infiltration ,Technology ,Science - Abstract
An additive manufacturing process for fabricating ceramic matrix composites has been developed based on the C/C-SiC system. Automated fiber placement of the continuous carbon fibers in a polyether ether ketone matrix was performed to consolidate the carbon fibers into a printed preform. Pyrolysis was performed to convert the polymer matrix to porous carbon, and then Si was introduced by reactive melt infiltration to convert a portion of the carbon matrix to silicon carbide. The densities and microstructures were characterized after each step during the processing, and the mechanical properties were measured. The C/C-SiC composites exhibited a porosity of 10–20%, characteristic flexural strength of 234.91 MPa, and Weibull modulus of 3.21. The composites displayed toughness via a significant displacement to failure.
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- 2022
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20. NGO Presence and Activity in Afghanistan, 2000–2014: A Provincial-Level Dataset
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David F. Mitchell
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International relations ,JZ2-6530 ,Political science (General) ,JA1-92 - Abstract
This article introduces a new provincial-level dataset on non-governmental organizations (NGOs) in Afghanistan. The data—which are freely available for download—provide information on the locations and sectors of activity of 891 international and local (Afghan) NGOs that operated in the country between 2000 and 2014. A summary and visualization of the data is presented in the article following a brief historical overview of NGOs in Afghanistan. Links to download the full dataset are provided in the conclusion.
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- 2017
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21. Continuous Enzymatic Prehydrolysis Treatment of High-Fat Wastewater
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Rodrigo Augusto Franco de Oliveira Zawadzki, Marcelo Real Prado, David Alexander Mitchell, and Nadia Krieger
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enzymatic hydrolysis ,lipases ,Rhizopus microsporus ,high-fat wastewater ,packed-bed bioreactor ,Biotechnology ,TP248.13-248.65 ,Food processing and manufacture ,TP368-456 - Abstract
A lipolytic fermented solid was produced by solid-state fermentation of Rhizopus microsporus CPQBA 312-07 DRM on a mixture of sugarcane bagasse and sunflower seed meal and used, in a packed-bed bioreactor, to pretreat a high-fat wastewater from a meat and sausage processing factory located in São José dos Pinhais, State of Paraná, Brazil. With a hydraulic residence time of 24 h, this pretreatment not only reduced the wastewater’s oil and grease content by up to 96 %, but also increased its 5-day biochemical oxygen demand to chemical oxygen demand (BOD5/COD) ratio. This ratio was only 0.19 in the raw wastewater, indicating poor biodegradability, but increased to 0.55 in the pretreated wastewater, indicating that it had a sufficiently high biodegradability to be sent to a traditional anaerobic digestion or activated sludge process. After 96 days of operation of the packed bed, a microbiological analysis showed that R. microsporus was still present and viable in the fermented solid. Our work shows that a continuous packed-bed bioreactor containing fermented solid produced by R. microsporus has good potential for the treatment of high-fat wastewater.
- Published
- 2013
22. Towards powerful experimental and statistical approaches to study intraindividual variability in labile traits
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David J. Mitchell, Benjamin G. Fanson, Christa Beckmann, and Peter A. Biro
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behavioural predictability ,behavioural plasticity ,residual model ,repeatability ,behavioural syndrome ,multiple burst ,Science - Abstract
There is a long-standing interest in behavioural ecology, exploring the causes and correlates of consistent individual differences in mean behavioural traits (‘personality’) and the response to the environment (‘plasticity’). Recently, it has been observed that individuals also consistently differ in their residual intraindividual variability (rIIV). This variation will probably have broad biological and methodological implications to the study of trait variation in labile traits, such as behaviour and physiology, though we currently need studies to quantify variation in rIIV, using more standardized and powerful methodology. Focusing on activity rates in guppies (Poecilia reticulata), we provide a model example, from sampling design to data analysis, in how to quantify rIIV in labile traits. Building on the doubly hierarchical generalized linear model recently used to quantify individual differences in rIIV, we extend the model to evaluate the covariance between individual mean values and their rIIV. After accounting for time-related change in behaviour, our guppies substantially differed in rIIV, and it was the active individuals that tended to be more consistent (lower rIIV). We provide annotated data analysis code to implement these complex models, and discuss how to further generalize the model to evaluate covariances with other aspects of phenotypic variation.
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- 2016
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23. Experimental and Modelling Study of Enzymatic Oxidation of 5-o-Caffeoylquinic Acid by Polyphenol Oxidases
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Tarcila Bueno dos Santos, David Alexander Mitchell, Nadia Krieger, Vivian Rotuno Moure, and Éverton Fernando Zanoelo
- Subjects
chlorogenic acids ,5-CQA ,enzymatic oxidation ,polyphenol oxidases ,Biotechnology ,TP248.13-248.65 ,Food processing and manufacture ,TP368-456 - Abstract
A set of experiments to investigate the enzymatic oxidation of 5-o-caffeoylquinic acid with polyphenol oxidases was carried out in the temperature range from 18 to 39 °C. The kinetic data were obtained in a batch isothermal reactor made of quartz and operated at an optimum pH (approx. 7.0) for enzyme activity, using citrate-phosphate buffer. The decay of 5-o-caffeoylquinic acid concentrations was experimentally monitored with a spectrophotometer at 323 nm. A coefficient of molar absorptivity equal to 1.96·103 mM–1m–1 was found for 5-o-caffeoylquinic acid, based on absorbance measurements with standard aqueous solutions. The kinetic experimental results were used to calculate the parameters Km and vmax of the Michaelis-Menten model, which were 0.24 mM and 2.77·10–4 mM/s at 25 °C, respectively. The effects of temperature on the maximum velocity of oxidation of 5-o-caffeoylquinic acid and on the rate of enzyme deactivation were well described using the Arrhenius equation.
- Published
- 2010
24. Production of a Fermented Solid Containing Lipases of Rhizopus microsporus and Its Application in the Pre-Hydrolysis of a High-Fat Dairy Wastewater
- Author
-
Dayane Alberton, David Alexander Mitchell, Jesús Cordova, Patrício Peralta-Zamora, and Nadia Krieger
- Subjects
lipolysis ,enzymatic pretreatment ,solid-state fermentation ,solid-state cultivation ,dairy wastewater ,Rhizopus microsporus ,Biotechnology ,TP248.13-248.65 ,Food processing and manufacture ,TP368-456 - Abstract
The filamentous fungus Rhizopus microsporus CPQBA 312-07 DRM was grown in solid-state cultivation and the fermented solid produced was used to hydrolyze triacylglycerols in a high-fat dairy wastewater. For the solid-state cultivation, a mixture of sunflower seed meal and sugarcane bagasse (1:3 by mass on dry basis) was selected. After 18 h of culture, the fermented product had an activity, measured titrimetrically against triolein, of 26 U per gram of dry solids. This substrate mixture does not suffer from compaction and therefore can be used in large scale solid-state cultivation bioreactors. When used to pretreat a high-fat dairy wastewater, with an oil and grease level above 1300 mg/L, the fermented solid reduced the oil and grease level to below 300 mg/L after 72 h at 35 °C. Further work is required to improve the production of lipolytic activity in the solid-state cultivation step and to find the optimum pretreatment time in the wastewater pretreatment step.
- Published
- 2010
25. Starch Depolymerization with Diluted Phosphoric Acid and Application of the Hydrolysate in Astaxanthin Fermentation
- Author
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David Alexander Mitchell, Oscar E. Molina, Anabella Gaitan, Tânia M.B. Bonfim, Juliana Adelmann, Adelia Grzybowski, Maurício Passos, and José Domingos Fontana
- Subjects
cassava starch ,phosphorolysis ,acid hydrolysis ,depolymerization ,phosphoric acid ,astaxanthin ,Biotechnology ,TP248.13-248.65 ,Food processing and manufacture ,TP368-456 - Abstract
An innovative alternative for cassava starch hydrolysis has been developed using diluted (about 0.1 %) phosphoric acid at 160 °C. This technology is advantageous for developing countries where enzyme costs are prohibitive and hydrochloric acid is currently the only catalyst used for starch depolymerization. Lower concentrations of the byproduct hydroxymethyl furfural (HMF) were generated during starch hydrolysis when using phosphoric acid as compared to hydrochloric acid at any given acidic pH. Glucose was the major product from phosphorolysed starch under most reaction conditions, although maltosaccharides with degrees of polymerization from 2 to 7 were also produced, with their relative amounts depending on hydrolysis conditions. Neutralization of the acid with aqueous ammonia produced a hydrolysate with sources of C (free sugars), P (phosphate), and N (ammonium) that could find several applications. We demonstrated one of these, namely the potential for the use of the hydrolysate as a fermentation feedstock, by cultivating the astaxanthin-producing red yeast Xanthophyllomyces dendrorhous on it. Cassava wastewater, a polluting byproduct of starch processing, was found to be a convenient source of nitrogen for this fermentation process.
- Published
- 2008
26. The Tyrosinase Produced by Lentinula boryana (Berk. & Mont.) Pegler Suffers Substrate Inhibition by L-DOPA
- Author
-
Rodrigo Otávio de Faria, Vivian Rotuno Moure, Wellington Balmant, Maria Angela Lopes de Almeida Amazonas, Nadia Krieger, and David Alexander Mitchell
- Subjects
tyrosinase ,Lentinula boryana ,substrate inhibition ,3,4-dihydroxy-L-phenylalanine ,L-DOPA ,Biotechnology ,TP248.13-248.65 ,Food processing and manufacture ,TP368-456 - Abstract
We undertook a preliminary characterization of the tyrosinase produced by a strain of Lentinula boryana from Brazil, with a view to evaluate its potential for biotechnological applications. The enzyme was similar to other fungal tyrosinases in many respects. When the crude extract was characterized, the tyrosinase activity was optimal at pH=6 and was not particularly thermostable, with half-lives of about 10 min and 1 min at 50 and 60 °C, respectively. We purified the enzyme with ammonium sulfate precipitation followed by ion exchange chromatography on a DEAE Sepharose column, obtaining a yield of 33 % and a 5.3-fold enrichment. The purified preparation gave three bands on SDS-PAGE, with molecular masses of 20, 27 and 47 kDa. This preparation showed substrate inhibition kinetics with L-DOPA (3,4-dihydroxy-L-phenylalanine), with a KM of 1.9 mM and a KI of 72 mM. Under the same reaction conditions, a commercial mushroom tyrosinase followed Michaelis-Menten kinetics, with a KM of 0.51 mM. Although the present study did not identify properties that would make the tyrosinase of L. boryana more suitable in biotechnological applications than tyrosinases from other mushrooms, it has made a contribution by showing that the enzyme suffers substrate inhibition by L-DOPA, something that has not previously been reported for mushroom tyrosinases.
- Published
- 2007
27. The Biotechnological Potential of Mushroom Tyrosinases
- Author
-
Rodrigo Otávio de Faria, Vivian Rotuno Moure, Maria Angela Lopes de Almeida Amazonas, David Alexander Mitchell, and Nadia Krieger
- Subjects
mushroom tyrosinase ,Agaricus bisporus ,biosensors ,cross-linked biopolymers ,phenol removal ,submerged culture ,Biotechnology ,TP248.13-248.65 ,Food processing and manufacture ,TP368-456 - Abstract
Over the last decade there has been a significant interest in developing biotechnological applications of tyrosinases. These applications include the production of L-DOPA (3,4-dihydroxyphenyl-L-alanine) from L-tyrosine, the production of cross-linked protein networks for use as novel food additives and the detection of phenolic compounds in wastewater or their removal from it. Much of the research into these applications has involved mushroom tyrosinases. We review the potential biotechnological applications of mushroom tyrosinases and evaluate the state of knowledge about their production, recovery and immobilization. We conclude that much more research is necessary in these areas if mushroom tyrosinases are to fulfill their biotechnological potential.
- Published
- 2007
28. Blurred Lines? Provincial Reconstruction Teams and NGO Insecurity in Afghanistan, 2010–2011
- Author
-
David F Mitchell
- Subjects
provincial reconstruction teams ,humanitarian security ,humanitarian aid ,International relations ,JZ2-6530 ,Political science (General) ,JA1-92 - Abstract
Members of nongovernmental organizations (NGOs) have been critical of the Provincial Reconstruction Team (PRT) initiative in Afghanistan since its inception, claiming that the mixture of military and humanitarian operations has resulted in ‘blurred lines’ that inhibit insurgents from identifying who is and is not a combatant. Certain organizations have hypothesized that aid workers are more likely to come under attack as a result of this mixture. Although this claim has surfaced in multiple outlets over the years, there was a lack of empirical evidence to support it. This study tests this hypothesis using a panel-corrected standard error regression model of all 34 Afghan provinces in 2010 and 2011. Preliminary results show that NGOs were likely to encounter a greater number of security incidents in provinces with PRTs; however, further analysis reveals this was only the case in provinces with teams not led by the US. This calls into question the validity of a general ‘blurred lines’ explanation for decreased aid worker security.
- Published
- 2015
- Full Text
- View/download PDF
29. Immobilization and characterization of a new regioselective and enantioselective lipase obtained from a metagenomic library.
- Author
-
Robson Carlos Alnoch, Viviane Paula Martini, Arnaldo Glogauer, Allen Carolina dos Santos Costa, Leandro Piovan, Marcelo Muller-Santos, Emanuel Maltempi de Souza, Fábio de Oliveira Pedrosa, David Alexander Mitchell, and Nadia Krieger
- Subjects
Medicine ,Science - Abstract
In previous work, a new lipase and its cognate foldase were identified and isolated from a metagenomic library constructed from soil samples contaminated with fat. This new lipase, called LipG9, is a true lipase that shows specific activities that are comparable to those of well-known industrially-used lipases with high activity against long-chain triglycerides. In the present work, LipG9 was co-expressed and co-immobilized with its foldase, on an inert hydrophobic support (Accurel MP1000). We studied the performance of this immobilized LipG9 (Im-LipG9) in organic media, in order to evaluate its potential for use in biocatalysis. Im-LipG9 showed good stability, maintaining a residual activity of more than 70% at 50 °C after incubation in n-heptane (log P 4.0) for 8 h. It was also stable in polar organic solvents such as ethanol (log P -0.23) and acetone (log P -0.31), maintaining more than 80% of its original activity after 8 h incubation at 30 °C. The synthesis of ethyl esters was tested with fatty acids of different chain lengths in n-heptane at 30 °C. The best conversions (90% in 3 h) were obtained for medium and long chain saturated fatty acids (C8, C14 and C16), with the maximum specific activity, 29 U per gram of immobilized preparation, being obtained with palmitic acid (C16). Im-LipG9 was sn-1,3-specific. In the transesterification of the alcohol (R,S)-1-phenylethanol with vinyl acetate and the hydrolysis of the analogous ester, (R,S)-1-phenylethyl acetate, Im-LipG9 showed excellent enantioselectivity for the R-isomer of both substrates (E> 200), giving an enantiomeric excess (ee) of higher than 95% for the products at 49% conversion. The results obtained in this work provide the basis for the development of applications of LipG9 in biocatalysis.
- Published
- 2015
- Full Text
- View/download PDF
30. A model for growth of a single fungal hypha based on well-mixed tanks in series: simulation of nutrient and vesicle transport in aerial reproductive hyphae.
- Author
-
Wellington Balmant, Maura Harumi Sugai-Guérios, Juliana Hey Coradin, Nadia Krieger, Agenor Furigo Junior, and David Alexander Mitchell
- Subjects
Medicine ,Science - Abstract
Current models that describe the extension of fungal hyphae and development of a mycelium either do not describe the role of vesicles in hyphal extension or do not correctly describe the experimentally observed profile for distribution of vesicles along the hypha. The present work uses the n-tanks-in-series approach to develop a model for hyphal extension that describes the intracellular transport of nutrient to a sub-apical zone where vesicles are formed and then transported to the tip, where tip extension occurs. The model was calibrated using experimental data from the literature for the extension of reproductive aerial hyphae of three different fungi, and was able to describe different profiles involving acceleration and deceleration of the extension rate. A sensitivity analysis showed that the supply of nutrient to the sub-apical vesicle-producing zone is a key factor influencing the rate of extension of the hypha. Although this model was used to describe the extension of a single reproductive aerial hypha, the use of the n-tanks-in-series approach to representing the hypha means that the model has the flexibility to be extended to describe the growth of other types of hyphae and the branching of hyphae to form a complete mycelium.
- Published
- 2015
- Full Text
- View/download PDF
31. A Model of the Effect of the Microbial Biomass on the Isotherm of the Fermenting Solids in Solid-State Fermentation
- Author
-
Barbara Celuppi Marques, Marcelo Calide Barga, Wellington Balmant, Luiz Fernando de Lima Luz Jr, Nadia Krieger, and David Alexander Mitchell
- Subjects
corn ,isotherms ,mathematical modelling ,Rhizopus oryzae ,soybeans ,SSF ,Biotechnology ,TP248.13-248.65 ,Food processing and manufacture ,TP368-456 - Abstract
We compare isotherms for soybeans and soybeans fermented with Rhizopus oryzae, showing that in solid-state fermentation the biomass affects the isotherm of the fermenting solids. Equations are developed to calculate, for a given overall water content of the fermenting solids, the water contents of the biomass and residual substrate, as well as the water activity. A case study, undertaken using a mathematical model of a well-mixed bioreactor, shows that if water additions are made on the basis of the assumption that fermenting solids have the same isotherm as the substrate itself, poor growth can result since the added water does not maintain the water activity at levels favorable for growth. We conclude that the effect of the microbial biomass on the isotherm of the fermenting solids must be taken into account in mathematical models of solid-state fermentation bioreactors.
- Published
- 2006
32. The LATD Gene of Medicago truncatula Is Required for Both Nodule and Root Development
- Author
-
Lydia J. Bright, Yan Liang, David M. Mitchell, and Jeanne M. Harris
- Subjects
bacteroid ,nodule development ,nodule evolution ,Microbiology ,QR1-502 ,Botany ,QK1-989 - Abstract
The evolutionary origins of legume root nodules are largely unknown. We have identified a gene,LATD, of the model legume Medicago truncatula, that is required for both nodule and root development, suggesting that these two developmental processes may share a common evolutionary origin. The latd mutant plants initiate nodule formation but do not complete it, resulting in immature, non-nitrogen-fixing nodules. Similarly, lateral roots initiate, but remain shortstumps. The primary root, which initially appears to be wild type, gradually ceases growth and forms an abnormal tipthat resembles that of the mutant lateral roots. Infection by the rhizobial partner, Sinorhizobium meliloti, can occur, although infection is rarely completed. Once inside latd mutant nodules, S. meliloti fails to express rhizobial genes associatedwith the developmental transition from free-living bacterium to endosymbiont, such as bacA and nex38. The infecting rhizobia also fail to express nifH and fix nitrogen. Thus, both plant and bacterial development are blocked in latd mutant roots. Based on the latd mutant phenotype, we propose that the wild-type function of the LATD gene is to maintain root meristems. The strong requirement of both nodules and lateral roots for wild-type LATD gene function supports lateral roots as a possible evolutionary origin for legume nodules.
- Published
- 2005
- Full Text
- View/download PDF
33. Current Techniques for the Cultivation of Ganoderma lucidum for the Production of Biomass, Ganoderic Acid and Polysaccharides
- Author
-
Ricardo Wagner, Guilherme Lanzi Sassaki, Maria Angela Lopes de Almeida Amazonas, Marin Berovič, and David Alexander Mitchell
- Subjects
Ganoderma lucidum ,submerged fermentation ,polysaccharide ,ganoderic acid ,Biotechnology ,TP248.13-248.65 ,Food processing and manufacture ,TP368-456 - Abstract
Ganoderma lucidum is a medicinal mushroom that has been used in the Orient for more than 2000 years. Due to the long time required for basidiocarp formation, attention has recently been given to the use of submerged fermentation for the production of mycelial biomass and its bioactive components, such as polysaccharides and ganoderic acids. We review the current state of knowledge about the cultivation of G. lucidum by modern fermentation techniques, focussing on the effects of fermentation conditions and how knowledge of these effects has been used to develop strategies for improving the production of biomass, polysaccharides and ganoderic acid. We also outline the methods that have been used for biomass and product recovery and point out potential problems involved in these steps. Studies to date have been almost entirely limited to laboratory scale and much more understanding of the physiology of G. lucidum and its relationship with growth morphology will be necessary before it will be possible to develop economical large scale processes.
- Published
- 2003
34. Introduction of a microsurgical in-vivo embolization-model in rats: the aorta-filter model.
- Author
-
Lucas M Ritschl, Andreas M Fichter, Monika von Düring, David A Mitchell, Klaus-Dietrich Wolff, and Thomas Mücke
- Subjects
Medicine ,Science - Abstract
Vascular thrombosis with subsequent distal embolization remains a critical event for patients. Prevention of this life-threatening event can be achieved pharmacologically or mechanically with intravascular filter systems. The ability to evaluate the risk of embolization of certain techniques and procedures in vascular and microvascular surgery, such as, tissue glue or fibrin based haemostatic agents lacks convincing models. We performed 64 microvascular anastomoses in 44 rats, including 44 micro-pore polyurethane filter-anastomoses and 20 non-filter anastomoses. The rats were re-anesthetized and the aorta was re-exposed and removed four hours, three, seven, fourteen, thirty-one days, and six months postoperatively. The specimens were examined macro- and microscopically with regard to the appearance of the vessel wall, condition of the filter and the amount of thrombembolic material. Typical postoperative histopathological changes in vessel architecture were observed. Media necrosis was the first significant change three days postoperatively. Localized intimal hyperplasia, media necrosis, increase of media fibromyocytes and adventitial hypercellularity were seen to a significant extent at day seven postoperatively. Significant neovascularization of adventitia adjacent to the filter was seen after 14 days. A significant amount of thrombotic material was seen after four hours, three and 14 days interval. Only three intravascular filters became completely occluded (6.82%). The aorta-filter-anastomosis model appeared to be a valid in-vivo model in situations at risk for thrombembolic events, for microsurgical research and allowed sensitive analysis of surgical procedures and protection of the vascularized tissue. It may be suitable for a wide range of in-vivo microvascular experiments particularly in the rat model.
- Published
- 2014
- Full Text
- View/download PDF
35. Pectinase activity determination: an early deceleration in the release of reducing sugars throws a spanner in the works!
- Author
-
Alessandra Biz, Fernanda Cardoso Farias, Francine Aline Motter, Diogo Henrique de Paula, Peter Richard, Nadia Krieger, and David Alexander Mitchell
- Subjects
Medicine ,Science - Abstract
Recently, it has been suggested that pectinases could be used to hydrolyze pectin in biorefineries based on pectin-rich agro-industrial wastes. However, for this to be viable, the cost of their production would need to be lowered significantly. In fact, over the last few decades, there have been many attempts to improve pectinase production by existing strains or to screen for new strains from environmental isolates. In these studies, it is necessary to measure pectinase activities. Many researchers use single-time-point assays that involve incubation of pectinolytic extracts with pectic substrates for a fixed time, followed by determination of the liberated reducing sugars. However, different researchers use quite different conditions for this assay. Furthermore, no attention has been given to the reaction profile during the assay. In the current work, we show, for the first time, that a significant deceleration of the rate of liberation of reducing sugars occurs over the first ten minutes of the reaction. As a consequence, the incubation time used in a single-time-point assay has a large effect on the value obtained for the activity. In fact, we demonstrate that, depending on the particular combination of incubation time, pectin concentration and reaction temperature, the same extract could be reported to have activities that differ by an order of magnitude. In addition, we show that the relative activities obtained with polygalacturonic acid do not correlate with those obtained with pectin. We conclude that it is currently impossible to make meaningful comparisons between pectinase activities reported in the literature by workers who have used different assay conditions. Therefore there is an urgent need for the development of a standardized assay for evaluating the saccharification potential of pectinase complexes.
- Published
- 2014
- Full Text
- View/download PDF
36. Cultural Locations of Disability
- Author
-
Sharon L. Snyder and David T. Mitchell
- Subjects
Social sciences (General) ,H1-99 - Published
- 2007
- Full Text
- View/download PDF
37. Plates
- Author
-
Andrew Ensoll, Geoffrey Harper, Bob Ursem, David R Mitchell, and Simon Crutchley
- Subjects
Botany ,QK1-989 - Abstract
No abstract
- Published
- 2004
- Full Text
- View/download PDF
38. Living Collection Curation
- Author
-
David R Mitchell
- Subjects
Botany ,QK1-989 - Abstract
The necessity to redesign and relandscape the interior of the Temperate Palmhouse at the Royal Botanic Garden Edinburgh (RBGE) created the opportunity to undertake a full curatorial survey of the palms and other plants contained in the Palmhouse. This paper gives the background to, and describes the process of, undertaking the survey. It stresses the need for maximum consultation with all interested parties to decide the fate of existing plants and make recommendations for new plantings. The result was a booklet describing the history and development of the Palmhouse, listings of all existing plants with notes on ethnobotanical use, value in teaching or research and final destination and suggestions for new species to meet the new design along with educational and interpretation opportunities. The resultant survey could act as a model for other projects.
- Published
- 2004
- Full Text
- View/download PDF
39. Commentary: Can Educational Technology Theory and Practice Benefit from Systems Analysis?
- Author
-
David P. Mitchell
- Subjects
Education - Published
- 1986
- Full Text
- View/download PDF
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