22,056 results for 2000, Journal article

  • High energy, low repetition rate, photonic crystal fiber generated supercontinuum for nanosecond to millisecond transient absorption spectroscopy

    Kho, JLH; Rohde, Charles; Vanholsbeeck, Frederique; Simpson, Miriam (2013-05-01)

    Journal article
    The University of Auckland Library

    High energy density per pulse (???15 dBm nm???1) supercontinuum (SC) source has been developed as a probe for transient absorption (TrA) spectroscopy of systems with lifetimes from nanoseconds to a few milliseconds. We have generated a 600???1600 nm, broadband SC by pumping a 15 m photonic crystal fiber (PCF) with relatively high power, 7 ns, 1064 nm pulses. The SC generated at peak pump power of 7.1 kW was randomly polarized and maintained a stable output (6.5% rms average power; 9.1% rms shot-to-shot power). Co-pumping with both 1064 and 532 nm light extended the wavelength range of the SC by about 20%, to 500???1700 nm. Power conversion efficiency and spectral flatness were improved as well. In the visible range, the single-pump SC shows a flatness of 5 dB while the dual-pump SC exhibits 3 dB. In the NIR (1100???1600 nm), the flatness in single- and dual-pump configurations were 3 and 2 dB, respectively. Optically induced fiber breakdown was characterized.

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  • The action of mimetic peptides on connexins protects fibroblasts from the negative effects of ischemia reperfusion

    Glass, BJ; Hu, RG; Phillips, Anthony; Becker, DL (2015)

    Journal article
    The University of Auckland Library

    Connexins have been proposed as a target for therapeutic treatment of a variety of conditions. The main approaches have been by antisense or small peptides specific against connexins. Some of these peptides enhance communication while others interfere with connexin binding partners or bind to the intracellular and extracellular loops of connexins. Here, we explored the mechanism of action of a connexin mimetic peptide by evaluating its effect on gap junction channels, connexin protein levels and hemichannel activity in fibroblast cells under normal conditions and following ischemia reperfusion injury which elevates Cx43 levels, increases hemichannel activity and causes cell death. Our results showed that the effects of the mimetic peptide were concentration-dependent. High concentrations (100-300?????M) significantly reduced Cx43 protein levels and GJIC within 2???h, while these effects did not appear until 6???h when using lower concentrations (10-30?????M). Cell death can be reduced when hemichannel opening and GJIC were minimised.

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  • Emerging roles of pro-resolving lipid mediators in immunological and adaptive responses to exercise-induced muscle injury

    Markworth, JF; Maddipati, KR; Cameron-Smith, David (2016)

    Journal article
    The University of Auckland Library

    Lipid mediators are bioactive metabolites of the essential polyunsaturated fatty acids (PUFA) that play diverse roles inthe initiation, self-limitation, and active resolution of inflammation. Prostaglandins, classical pro-inflammatory lipid metabolites of arachidonic acid, have long been implicated in immunological and adaptive muscle responses to acute injury and exercise-induced stress. More recently, PUFA metabolites have been discovered during the resolution phase of inflammation which collectively function as endogenous 'stop signals' to control inflammation whilst actively promoting the return to a non-inflamed state. The apparent self-resolving nature of inflammatory responses holds important implications for contexts of musculoskeletal injury, exercise recovery, and chronic inflammatory diseases originati ng in or impacting upon muscle. 'Anti-inflammatory' interventions that strive to control inflammation via antagonism of pro-inflammatory signals are currently commonplace in efforts to hasten muscle recovery from damaging or exhaustive exercise, as well as to relieve the pain associated with musculoskeletal injury. However, the scientific literature does not clearly support a benefit of this anti-inflammatory approach. Additionally, recent evidence suggests that strategies to block pro-inflammatory lipid mediator pathways (e.g. NSAIDs) may be counterintuitive and inadvertently derange or impair timely resolution of inflammation; with potentially deleterious implications on skeletal muscle remodelling. The current review will provide an overview of the current understanding of diverse roles of bioactive lipid mediators in the initiation, control, and active resolution of acute inflammation. The established and putative roles of lipid mediators in mediating immunological and adapt ive skeletal muscle responses to acute muscle injury and exercise-induced muscle load/stress will be discussed.

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  • N-2, N-2, 7-trimethylguanine, a new trimethylated guanine natural product from the New Zealand ascidian, Lissoclinum notti

    Pearce, Allison; Babcock, Russell; Lambert, G; Copp, Brent (2001)

    Journal article
    The University of Auckland Library

    From the New Zealand ascidian, Lissoclinum notti a new natural product, N-2,N-2,7-trimethylguanine (1) has been isolated. The structure of 1 was elucidated by analysis of spectroscopic data.

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  • 1,3-dimethyl-8-oxoisoguanine, a new purine from the New Zealand ascidian Pseudodistoma Cereum

    Appleton, David; Page, MJ; Lambert, G; Copp, Brent (2004-02)

    Journal article
    The University of Auckland Library

    A new purine, 1,3-dimethyl-8-oxoisoguanine (2) was isolated from the New Zealand ascidian Pseudodistoma cereum. The structure of 2 was elucidated by the use of standard spectroscopic techniques, including natural abundance H-1-N-15 2D NMR.

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  • Kottamide E, the first example of a natural product bearing the amino acid 4-amino-1,2-dithiolane-4-carboxylic acid (Adt)

    Appleton, David; Copp, Brent (2003-12-08)

    Journal article
    The University of Auckland Library

    Kottamide E, a novel alkaloid containing dibrominated indole enamide, oxalic acid diamide and 4-amino-1,2-dithiolane-4-carboxamide moieties, has been isolated from the New Zealand ascidian Pycnoclavella kottae. Characterisation was achieved by interpretation of spectroscopic data.

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  • Mortality and hospitalisation costs of rheumatic fever and rheumatic heart disease in New Zealand.

    Milne, Richard; Lennon, Diana; Stewart, Joanna; Vander Hoorn, S; Scuffham, PA (2012-08)

    Journal article
    The University of Auckland Library

    Aims:??? To estimate the annual mortality and the cost of hospital admissions for acute rheumatic fever (ARF) and rheumatic heart disease (RHD) for New Zealand residents. Methods:??? Hospital admissions in 2000-2009 with a principal diagnosis of ARF or RHD (ICD9_AM 390-398; ICD10-AM I00-I099) and deaths in 2000-2007 with RHD as the underlying cause were obtained from routine statistics. The cost of each admission was estimated by multiplying its diagnosis-related group (DRG) cost weight by the national price for financial year 2009/2010. Results:??? There were on average 159 RHD deaths each year with a mean annual mortality rate of 4.4 per 100???000 (95% confidence limit 4.2, 4.7). Age-adjusted mortality was five- to 10-fold higher for M??ori and Pacific peoples than for non-M??ori/Pacific. The mean age at RHD death (male/female) was 56.4/58.4 for M??ori, 50.9/59.8 for Pacific and 78.2/80.6 for non-M??ori, non-Pacific men and women. The average annual DRG-based cost of hospital admissions in 2000-2009 for ARF and RHD across all age groups was $12.0???million (95% confidence limit $11.1???million, $12.8???million). Heart valve surgery accounted for 28% of admissions and 71% of the cost. For children 5-14???years of age, valve surgery accounted for 7% of admissions and 27% of the cost. Two-thirds of the cost occurs after the age of 30. Conclusions:??? ARF and RHD comprise a burden of mortality and hospital cost concentrated largely in middle age. M??ori and Pacific RHD mortality rates are substantially higher than those of non-M??ori/Pacific.

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  • Incidence of acute rheumatic fever in New Zealand children and youth.

    Milne, Richard; Lennon, Diana; Stewart, Joanna; Vander Hoorn, S; Scuffham, PA (2012-08)

    Journal article
    The University of Auckland Library

    Aim:??? To estimate acute rheumatic fever (ARF) incidence rates for New Zealand children and youth by ethnicity, socioeconomic deprivation and region. Methods:??? National hospital admissions with a principal diagnosis of ARF (ICD9_AM 390-392; ICD10-AM I00-I02) were obtained from routine statistics and stratified by age, ethnicity, socioeconomic deprivation index (NZDep2006) and District Health Board (DHB). Results:??? The mean incidence rate for ARF in 2000-2009 peaked at 9 to 12???years of age. Incidence rates for children 5 to 14???years of age for M??ori were 40.2 (95% confidence interval 36.8, 43.8), Pacific 81.2 (73.4, 89.6), non-M??ori/Pacific 2.1 (1.6, 2.6) and all children 17.2 (16.1, 18.3) per 100???000. M??ori and Pacific incidence rates increased by 79% and 73% in 1993-2009, while non-M??ori/Pacific rates declined by 71%. Overall rates increased by 59%. In 2000-2009, M??ori and Pacific children comprised 30% of children 5-14???years of age but accounted for 95% of new cases. Almost 90% of index cases of ARF were in the highest five deciles of socioeconomic deprivation and 70% were in the most deprived quintile. A child living in the most deprived decile has about one in 150 risk of being admitted to the hospital for ARF by 15???years of age. Ten DHBs containing 76% of the population 5 to 14???years of age accounted for 94% of index cases of ARF. Conclusions:??? ARF with its attendant rheumatic heart disease is an increasing public health issue for disadvantaged North Island communities with high concentrations of M??ori and/or Pacific families.

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  • Crisis in clinical care: an approach to management

    Runciman, WB; Merry, Alan (2005)

    Journal article
    The University of Auckland Library

    A "crisis" in health care is "the point in the course of a disease at which a decisive change occurs, leading either to recovery or to death". The daunting challenges faced by clinicians when confronted with a crisis are illustrated by a tragic case in which a teenage boy died after a minor surgical procedure. Crises are challenging for reasons which include: presentation with non-specific signs or symptoms, interaction of complex factors, progressive evolution, new situations, "revenge effects", inadequate assistance, and time constraints. In crises, clinicians often experience anxiety- and overload-induced performance degradation, tend to use "frequency gambling", run out of "rules" and have to work from first principles, and are prone to "confirmation bias". The effective management of crises requires formal training, usually simulator-based, and ideally in the inter-professional groups who will need to function as a team. "COVER ABCD-A SWIFT CHECK" is a pre-compiled algorithm which can be applied quickly and effectively to facilitate a systematic and effective response to the wide range of potentially lethal problems which may occur suddenly in anaesthesia. A set of 25 articles describing additional pre-compiled responses collated into a manual for the management of any crisis under anaesthesia has been published electronically as companion papers to this article. This approach to crisis management should be applied to other areas of clinical medicine as well as anaesthesia.

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  • Reply to N Hoem

    Albert, Benjamin; Behrensdorf Derraik, Jose; Garg, ML; Cameron-Smith, David; Hofman, Paul; Cutfield, Wayne (2016-06)

    Journal article
    The University of Auckland Library

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  • Dispensing data captures individual-level use of aspirin for cardiovascular disease prevention, despite availability over-the-counter

    Selak, Vanessa; Gu, Y; Rafter, N; Crengle, S; Kerr, Andrew; Bullen, Christopher (2016-05-27)

    Journal article
    The University of Auckland Library

    To assess the level of agreement in aspirin use measured by self-report and dispensing data.We assessed preventive cardiovascular medication use (prescription-only statins and blood pressure-lowering therapy; and aspirin-also available over-the-counter) at baseline in participants in the New Zealand IMPACT trial for whom these medications were prescribed by their general practitioner. A trial nurse not involved in their ongoing health care obtained participants' self-reported aspirin use data. We obtained dispensing data from the national pharmaceutical dispensing database and assessed agreement between the two measures using kappa coefficients.Of the 513 trial participants, 36% were women, 50% were of M??ori ethnicity, and 45% had a history of cardiovascular disease. The level of agreement between self-reported aspirin use and dispensing data was substantial (kappa 0.75, 95% CI 0.69 to 0.82). The level of agreement in aspirin use measured by these two sources of data was similar to that for statin and blood pressure-lowering therapy use, for all participants combined, for subgroups according to ethnicity (M??ori and non-M??ori) and history of cardiovascular disease.Despite its availability over-the-counter, aspirin use in patients for whom cardiovascular medications are indicated can be assessed accurately from dispensing data.

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  • Atypical white matter microstructure in left-handed individuals

    McKay, NS; Iwabuchi, SJ; H??berling, IS; Corballis, Michael; Kirk, Ian (2017-05)

    Journal article
    The University of Auckland Library

    Information regarding anatomical connectivity in the human brain can be gathered using diffusion tensor imaging (DTI). Fractional anisotropy (FA) is the most commonly derived value, and reflects how strongly directional are the underlying tracts. Differences in FA are thus associated with differences in the underlying microstructure of the brain. The relationships between these differences in microstructure and functional differences in corresponding regions have also been examined. Previous studies have found an effect of handedness on functional lateralization in the brain and corresponding microstructural differences. Here, using tract-based spatial statistics to analyse DTI-derived FA values, we further investigated the structural white matter architecture in the brains of right- and left-handed males. We found significantly higher FA values for left-handed, relatively to right-handed, individuals, in all major lobes, and in the corpus callosum. In support of previous suggestions, we find that there is a difference in the microstructure of white matter in left- and right-handed males that could underpin reduced lateralization of function in left-handed individuals.

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  • Novel roles for the lens in preserving overall ocular health

    Lim, Julie; Umapathy, A; Grey, Angus; Vaghefi Rezaei, Seyed; Donaldson, Paul (2017-03)

    Journal article
    The University of Auckland Library

    Outside the traditional roles of the lens as an important refractive element and a UV filter, it was David Beebe's group that first demonstrated that the lens acts an oxygen sink that protects the tissues of the anterior segment of the eye from oxygen or oxygen metabolites. In this review, we follow on from this work, and present new evidence from our laboratory to demonstrate that the lens serves as a reservoir for the release of the antioxidant glutathione (GSH) into the aqueous humor to provide a source of GSH and/or its precursor amino acids to nearby tissues that interface with the aqueous humor, or to remove toxic metabolites from the eye via the aqueous outflow pathway. In addition to GSH release, our laboratory and others have shown that ATP is released from the lens under hyposmotic conditions to activate purinergic signalling pathways in an autocrine manner to alter lens function. In this review, we raise the idea that ATP and/or its subsequent degradation product adenosine may exert a paracrine function and influence purinergic signalling systems in other tissues to alter aqueous humor outflow. These new secondary roles indicate that the lens is not just a passive optical element, but a highly dynamic and active tissue that interacts with its neighbouring tissues, through modifying the environments in which these tissues function. We believe that the lens actively contributes to the ocular environment and as a consequence, removal of the lens would alter the functionality of neighbouring tissues. We speculate that a long term effect of lens removal may be to inadvertently increase the exposure of anterior tissues of the eye to oxidative stress due to elevated oxygen levels and a reduction in the availability of GSH and purinergic signalling molecules in the aqueous humor. Since cataract surgery is now being performed on younger patients due to our increasing diabetic population, over time, we predict these changes may increase the susceptibility of these tissues to oxidative stress and the incidence of subsequent ocular pathologies. If our view of the lens is correct, the actual loss of the biological lens may have longer term consequences for overall ocular health than currently appreciated.

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  • The Effects of Maternal Under-Nutrition and a Post-Natal High Fat Diet on Lens Growth, Transparency and Oxidative Defense Systems in Rat Offspring

    Jayaratne, SK; Donaldson, Paul; Vickers, Mark; Lim, Julie (2017-04)

    Journal article
    The University of Auckland Library

    A poor early life nutrition environment is well established to result in a range of cardiometabolic disorders in offspring in later life. These effects can be exacerbated via exposure to an obesogenic dietary environment. To date, the effect of maternal diet and/or a post-natal obesogenic nutritional environment on key characteristics related to lens growth and oxidative stress has not been undertaken. The present study, therefore, examined the characteristics and oxidative status of the lens.Using a model of moderate maternal under-nutrition, rat dams were fed either a control diet (100% ad libitum, CON) or undernourished throughout pregnancy (50% of ad libitum intake, UN) and offspring fed either a control (5% fat, C) or high fat (30% fat, HF) diet post-weaning, resulting in four nutritional groups; CON-C, CON-HF, UN-C, and UN-HF. Offspring lenses were extracted at 160 days of age, weighed, imaged under dark and bright field microscopy, and then dissected into cortical and core fractions for biochemical analyses of oxidative stress markers.Our findings reveal that lenses from all groups were transparent. However, gender specific changes were evident at the biochemical level with increased oxidative stress detected in the cortex and core of female but not male UN-C lenses, and in the cortex of male but not female CON-HF lenses. The greatest increase in oxidative stress was detected in the UN-HF group in the cortex and core regions of the lens and for both genders.These findings show that oxidative stress is exacerbated in the lens as a result of a combination of altered pre-natal and post-natal diet. This demonstrates a novel interaction between the two developmental windows and warrants further investigations toward devising appropriate nutritional strategies for minimizing oxidative stress in the lens.

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  • Theory-based pharmacokinetics and pharmacodynamics of S- and R-warfarin and effects on international normalized ratio: influence of body size, composition and genotype in cardiac surgery patients

    Xue, L; Holford, Nicholas; Ding, X-L; Shen, Z-Y; Huang, C-R; Zhang, H; Zhang, J-J; Guo, Z-N; Xie, C; Zhou, L; Chen, Z-Y; Liu, L-S; Miao, L-Y (2017-04)

    Journal article
    The University of Auckland Library

    The aims of this study are to apply a theory-based mechanistic model to describe the pharmacokinetics (PK) and pharmacodynamics (PD) of S- and R-warfarin.Clinical data were obtained from 264 patients. Total concentrations for S- and R-warfarin were measured by ultra-high performance liquid tandem mass spectrometry. Genotypes were measured using pyrosequencing. A sequential population PK parameter with data method was used to describe the international normalized ratio (INR) time course. Data were analyzed with NONMEM. Model evaluation was based on parameter plausibility and prediction-corrected visual predictive checks.Warfarin PK was described using a one-compartment model. CYP2C9 *1/*3 genotype had reduced clearance for S-warfarin, but increased clearance for R-warfarin. The in vitro parameters for the relationship between prothrombin complex activity (PCA) and INR were markedly different (A??=??0.560, B??=??0.386) from the theory-based values (A??=??1, B??=??0). There was a small difference between healthy subjects and patients. A sigmoid Emax PD model inhibiting PCA synthesis as a function of S-warfarin concentration predicted INR. Small R-warfarin effects was described by competitive antagonism of S-warfarin inhibition. Patients with VKORC1 AA and CYP4F2 CC or CT genotypes had lower C50 for S-warfarin.A theory-based PKPD model describes warfarin concentrations and clinical response. Expected PK and PD genotype effects were confirmed. The role of predicted fat free mass with theory-based allometric scaling of PK parameters was identified. R-warfarin had a minor effect compared with S-warfarin on PCA synthesis. INR is predictable from 1/PCA in vivo.

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  • Wind turbine blade optimisation with individual pitch and trailing edge flap control

    Chen, Zhenrong; Stol, Karl; Mace, Brian (2016-11-07)

    Journal article
    The University of Auckland Library

    Individual pitch control and trailing edge flaps have been shown to be capable of reducing flapwise fatigue loads on wind turbine blades, with research to date focusing on controller development and performance assessment. This work covers development of a blade optimisation process which integrates synthesis of individual pitch and trailing edge flap controllers to evaluate their impact on the levelised cost of energy. The optimisation process selects blade chord, twist and material distributions, along with the spar cap width, and integrates a turbine cost and mass model with existing simulation codes. Constraints based on ultimate stresses, fatigue damage, blade deflection, resonant frequency, and rotor thrust are considered. Using the NREL 5 MW reference turbine as an initial point, reductions in the levelised cost of energy of 1.05% are obtained with collective pitch control only, while the addition of individual pitch control increases this reduction to 1.17%. The use of trailing edge flaps on top of individual pitch control increases the reduction in the levelised cost of energy to 1.27%. Blade mass and material cost reductions from 13.6 to 16.4% and 18.1???21.5% respectively are also obtained. Optimised blade designs are driven by blade deflection, rotor thrust and ultimate stresses in the spar cap.

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  • Incidence and predictors of oral feeding intolerance in acute pancreatitis: A systematic review, meta-analysis, and meta-regression.

    Bevan, MG; Asrani, VM; Bharmal, Sakina; Wu, LM; Windsor, John; Petrov, Maxim (2017-06)

    Journal article
    The University of Auckland Library

    Tolerance of oral food is an important criterion for hospital discharge in patients with acute pancreatitis. Patients who develop oral feeding intolerance have prolonged hospitalisation, use additional healthcare resources, and have impaired quality of life. This study aimed to quantify the incidence of oral feeding intolerance, the effect of confounders, and determine the best predictors of oral feeding intolerance.Clinical studies indexed in three electronic databases (EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials) were reviewed. Incidence and predictor data were meta-analysed and possible confounders were investigated by meta-regression analysis.A total of 22 studies with 2024 patients met the inclusion criteria, 17 of which (with 1550 patients) were suitable for meta-analysis. The incidence of oral feeding intolerance was 16.3%, and was not affected by WHO region, age, sex, or aetiology of acute pancreatitis. Nine of the 22 studies investigated a total of 62 different predictors of oral feeding intolerance. Serum lipase level prior to refeeding, pleural effusions, (peri)pancreatic collections, Ranson score, and Balthazar score were found to be statistically significant in meta-analyses.Oral feeding intolerance affects approximately 1 in 6 patients with acute pancreatitis. Serum lipase levels of more than 2.5 times the upper limit of normal prior to refeeding is a potentially useful threshold to identify patients at high risk of developing oral feeding intolerance.

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  • Special Issue: ???Organic Reactions in Green Solvents???

    Sperry, Jonathan; Garc??a-??lvarez, J (2016-11)

    Journal article
    The University of Auckland Library

    To overcome the well-established drawbacks of conventional organic solvents (toxicity, non-biodegradability, flammability, accumulation in the atmosphere) remarkable research efforts have been recently devoted to the replacement of traditional organic reaction media by the so-called Green Solvents. In this sense, the choice of a safe, non-toxic, biorenewable and cheap reaction media is a crucial goal in organic synthesis. Thus, this Special Issue on ???Organic Reactions in Green Solvents??? has been aimed to showcase a series of stimulating contributions from international experts within different sub-areas of organic synthesis in Green Solvents (ranging from metal- to organo-catalyzed organic reactions).

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  • Synthesis of the Azepinobisindole Alkaloid Iheyamine A Enabled by a Cross-Mannich Reaction

    Lindsay, Ashley; Leung, Ka Ho Ivanhoe; Sperry, Jonathan (2016-10-05)

    Journal article
    The University of Auckland Library

    The total synthesis of the azepinobisindole alkaloid iheyamine A is described. The successful strategy hinged on an intermolecular cross-Mannich reaction between 5-methoxy-3-acetoxyindole and a protected tryptamine to access an unsymmetrical 2,2???-bisindole, which was subsequently converted into iheyamine A via a deep-blue 3-indolone intermediate. VT 1H NMR infers that iheyamine A exists as a mixture of tautomers that undergo intermediate chemical exchange on the NMR time scale. The intermolecular cross-Mannich reaction described herein is a viable alternative to metal-catalyzed cross-coupling strategies commonly employed to access 2,2???-bisindoles.

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  • On maximal parabolic regularity for non-autonomous parabolic operators

    Disser, K; ter Elst, Antonius; Rehberg, J (2017-02-05)

    Journal article
    The University of Auckland Library

    We consider linear inhomogeneous non-autonomous parabolic problems associated to sesquilinear forms, with discontinuous dependence of time. We show that for these problems, the property of maximal parabolic regularity can be extrapolated to time integrability exponents r???2. This allows us to prove maximal parabolic Lr-regularity for discontinuous non-autonomous second-order divergence form operators in very general geometric settings and to prove existence results for related quasilinear equations.

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