On identifiability for chemical systems from measurable variables

The final publication is available at Springer via http://dx.doi.org/10.1007/s10910-013-0149-4The dynamics of the composition of chemical species in reacting systems can be characterized by a set of autonomous differential equations derived from mass conservation principles and some elementary hypothesis related to chemical reactivity. These sets of ordinary differential equations are basically non-linear, their complexity grows as much increases the number of substances present in the reacting media an can be characterized by a set of phenomenological constants which contains all the relevant information about the physical system. The determination of these kinetic constants is critical for the design or control of chemical systems from a technological point of view but the non-linear nature of the equations implies that there are hidden correlations between the parameters which maybe can be revealed with a identifiability analysis.This work has been partially supported by MTM2010-18228.Cantó Colomina, B.; Coll, C.; Sánchez, E.; Cardona Navarrete, SC.; Navarro-Laboulais, J. (2014). On identifiability for chemical systems from measurable variables. Journal of Mathematical Chemistry. 52(4):1023-1035. https://doi.org/10.1007/s10910-013-0149-4S10231035524M.J. Almendral, A. Alonso, M.S. Fuentes, Development of new methodologies for on-line determination of the bromate. J. Environ. Monit. 11, 1381–1388 (2009)A. Ben-Zvi, P.J. McLellan, K.B. McAuley, Identifiability of linear time-invariant differential-algebraic systems. I. The generalized Markov parameter approach. Ind. Eng. Chem. Res. 42, 6607–6618 (2003)T.P. Bonacquisti, A drinking water utility’s perspective on bromide, bromate, and ozonation. Toxicology 221, 145–148 (2006)R. Butler, A. Godley, L. Lytton, E. Cartmell, Bromate environmental contamination: review of impact and possible treatment. Crit. Rev. Environ. Sci. Tech. 35, 193–217 (2005)R. Butler, L. Lytton, A.R. Godley, I.E. Tothill, E. Cartmell, Bromate analysis in groundwater and wastewater samples. J. Environ. Monit. 7, 999–1006 (2005)B. Cantó, S.C. Cardona, C. Coll, J. Navarro-Laboulais, E. Sánchez, Dynamic optimization of a gas-liquid reactor. J. Math. Chem. 50, 381–393 (2012)B. Cantó, C. Coll and E. Sánchez, Identifiability of a class of discretized linear partial differential algebraic equations, Math. Problems Eng. 2011, 1–12 (2011)A. Constantinides, N. Mostoufi, Numerical Methods for Chemical Engineers with MATLAB Applications, Alkis Constantinides and Navid Mostoufi, Upper Saddle River (Prentice Hall, New Jersey, 1999)P. Englezos, N. Kalogerakis, Applied Parameter Estimation for Chemical Engineers (Marcel Dekker, New York, 2001)U. von Gunten, Ozonation of drinking water. Part II. Disinfection and by-product formation in presence of bromide, iodide or chlorine. Water Res. 37, 1469–1487 (2003)B. Legube, B. Parinet, K. Gelinet, F. Berne, J-Ph Croue, Modeling of bromate formation by ozonation of surface waters in drinking water treatment. Water Res. 38, 2185–2195 (2004)Q. Liu, L.M. Schurter, C.E. Muller, S. Aloisio, J.S. Francisco, D.W. Margerum, Kinetics and mechanisms of aqueous ozone reactions with bromide, sulfite, hydrogen sulfite, iodide, and nitrite ions. Inorg. Chem. 40, 4436–4442 (2001)J.B. Rawling, J.G. Ekerdt, Chemical Reactor Analysis and Design Fundamentals (Nob Hill Pub, Madison, 2002)W.E. Stewart, M. Caracotsios, Computer Aided Modelling of Reactive Systems (John Wiley and Sons, New York, 2008)P. Westerhoff, R. Song, G. Amy, R. Minear, Numerical kinetic models for bromide oxidation to bromine and bromate. Water Res. 32, 1687–1699 (1998)World Health Organization, Bromate in Drinking-water, Document WHO/SDE/WSH/05.08/78, http://www.who.int/water_sanitation_health/dwq/chemicals/en/ (accesed 26/07/12

Chirped pulse Raman amplification in warm plasma: towards controlling saturation

Stimulated Raman backscattering in plasma is potentially an efficient method of amplifying laser pulses to reach exawatt powers because plasma is fully broken down and withstands extremely high electric fields. Plasma also has unique nonlinear optical properties that allow simultaneous compression of optical pulses to ultra-short durations. However, current measured efficiencies are limited to several percent. Here we investigate Raman amplification of short duration seed pulses with different chirp rates using a chirped pump pulse in a preformed plasma waveguide. We identify electron trapping and wavebreaking as the main saturation mechanisms, which lead to spectral broadening and gain saturation when the seed reaches several millijoules for durations of 10's - 100's fs for 250 ps, 800 nm chirped pump pulses. We show that this prevents access to the nonlinear regime and limits the efficiency, and interpret the experimental results using slowly-varying-amplitude, current-averaged particle-in-cell simulations. We also propose methods for achieving higher efficiencies.close0

The role of predicted chemotactic and hydrocarbon degrading taxa in natural source zone depletion at a legacy petroleum hydrocarbon site

Petroleum hydrocarbon contamination is a global problem which can cause long-term environmental damage and impacts water security. Natural source zone depletion (NSZD) is the natural degradation of such contaminants. Chemotaxis is an aspect of NSZD which is not fully understood, but one that grants microorganisms the ability to alter their motion in response to a chemical concentration gradient potentially enhancing petroleum NSZD mass removal rates. This study investigates the distribution of potentially chemotactic and hydrocarbon degrading microbes (CD) across the water table of a legacy petroleum hydrocarbon site near Perth, Western Australia in areas impacted by crude oil, diesel and jet fuel. Core samples were recovered and analysed for hydrocarbon contamination using gas chromatography. Predictive metagenomic profiling was undertaken to infer functionality using a combination of 16 S rRNA sequencing and PICRUSt2 analysis. Naphthalene contamination was found to significantly increase the occurrence of potential CD microbes, including members of the Comamonadaceae and Geobacteraceae families, which may enhance NSZD. Further work to explore and define this link is important for reliable estimation of biodegradation of petroleum hydrocarbon fuels. Furthermore, the outcomes suggest that the chemotactic parameter within existing NSZD models should be reviewed to accommodate CD accumulation in areas of naphthalene contamination, thereby providing a more accurate quantification of risk from petroleum impacts in subsurface environments, and the scale of risk mitigation due to NSZD

Advances in Glucocorticoid-Induced Osteoporosis

Glucocorticoid-induced osteoporosis (GIOP) is one of the most important side effects of glucocorticoid use, as it leads to an increased risk of fractures. Recently, many published studies have focused on the cellular and molecular mechanisms of bone metabolism, the pathophysiology of GIOP, and the intervention options to prevent GIOP. In this review, recent advances in GIOP are summarized, particularly recent progress in our understanding of the mechanisms of GIOP resulting in improved insight that might result in the development of new treatment options in the near future

The effect of using an interactive booklet on childhood respiratory tract infections in consultations: Study protocol for a cluster randomised controlled trial in primary care

Background: Respiratory tract infections in children result in more primary care consultations than any other acute condition, and are the most common reason for prescribing antibiotics (which are largely unnecessary). About a fifth of children consult again for the same illness episode. Providing parents with written information on respiratory tract infections may result in a reduction in re-consultation rates and antibiotic prescribing for these illnesses. Asking clinicians to provide and discuss the information during the consultation may enhance effectiveness. This paper outlines the protocol for a study designed to evaluate the use of a booklet on respiratory tract infections in children within primary care consultations. Methods/Design: This will be a cluster randomised controlled trial. General practices will be randomised to provide parents consulting because their child has an acute respiratory tract infection with either an interactive booklet, or usual care. The booklet provides information on the expected duration of their child's illness, the likely benefits of various treatment options, signs and symptoms that should prompt re-consultation, and symptomatic treatment advice. It has been designed for use within the consultation and aims to enhance communication through the use of specific prompts. Clinicians randomised to using the interactive booklet will receive online training in its use. Outcomes will be assessed via a telephone interview with the parent two weeks after first consulting. The primary outcome will be the proportion of children who re-consult for the same illness episode. Secondary outcomes include: antibiotic use, parental satisfaction and enablement, and illness costs. Consultation rates for respiratory tract infections for the subsequent year will be assessed by a review of practice notes. Discussion: Previous studies in adults and children have shown that educational interventions can result in reductions in re-consultation rates and use of antibiotics for respiratory tract infections. This will be the first study to determine whether providing parents with a booklet on respiratory tract infections in children, and discussing it with them during the consultation, reduces re-consultations and antibiotic use for the same illness without reducing satisfaction with care. Trial registration: Current Controlled Trials ISRCTN46104365 </p

Limitations and potentials of dual-purpose cow herds in Central Coastal Veracruz, Mexico

Feed chemical and kinetic composition and animal performance information was used to evaluate productivity limitations and potentials of dual-purpose member herds of the Genesis farmer organization of central coastal Veracruz, Mexico. The Cornell Net Carbohydrate and Protein System model (Version 6.0) was systematically applied to specific groups of cows in structured simulations to establish probable input–output relationships for typical management, and to estimate probable outcomes from alternative management based on forage-based dietary improvements. Key herd vulnerabilities were pinpointed: chronic energy deficits among dry cows of all ages in late gestation and impeded growth for immature cows. Regardless of the forage season of calving, most cows, if not all, incur energy deficits in the final trimester of gestation; thus reducing the pool of tissue energy and constraining milking performance. Under typical management, cows are smaller and underweight for their age, which limits feed intake capacity, milk production and the probability of early postpartum return to ovarian cyclicity. The substitution of good-quality harvested forage for grazing increased predicted yields by about one-third over typical scenarios for underweight cows. When diets from first parturition properly supported growth and tissue repletion, milk production in second and third lactations was predicted to improve about 60%. Judiciously supplemented diets based on good quality grass and legume forages from first calving were predicted to further increase productivity by about 80% across a three-lactation cow lifetime. These dual-purpose herd owners have large incentives to increase sales income by implementing nutritional strategies like those considered in this study

Early symptoms in symptomatic and preclinical genetic frontotemporal lobar degeneration

OBJECTIVES: The clinical heterogeneity of frontotemporal dementia (FTD) complicates identification of biomarkers for clinical trials that may be sensitive during the prediagnostic stage. It is not known whether cognitive or behavioural changes during the preclinical period are predictive of genetic status or conversion to clinical FTD. The first objective was to evaluate the most frequent initial symptoms in patients with genetic FTD. The second objective was to evaluate whether preclinical mutation carriers demonstrate unique FTD-related symptoms relative to familial mutation non-carriers. METHODS: The current study used data from the Genetic Frontotemporal Dementia Initiative multicentre cohort study collected between 2012 and 2018. Participants included symptomatic carriers (n=185) of a pathogenic mutation in chromosome 9 open reading frame 72 (C9orf72), progranulin (GRN) or microtubule-associated protein tau (MAPT) and their first-degree biological family members (n=588). Symptom endorsement was documented using informant and clinician-rated scales. RESULTS: The most frequently endorsed initial symptoms among symptomatic patients were apathy (23%), disinhibition (18%), memory impairments (12%), decreased fluency (8%) and impaired articulation (5%). Predominant first symptoms were usually discordant between family members. Relative to biologically related non-carriers, preclinical MAPT carriers endorsed worse mood and sleep symptoms, and C9orf72 carriers endorsed marginally greater abnormal behaviours. Preclinical GRN carriers endorsed less mood symptoms compared with non-carriers, and worse everyday skills. CONCLUSION: Preclinical mutation carriers exhibited neuropsychiatric symptoms compared with non-carriers that may be considered as future clinical trial outcomes. Given the heterogeneity in symptoms, the detection of clinical transition to symptomatic FTD may be best captured by composite indices integrating the most common initial symptoms for each genetic group

Phase Shift from a Coral to a Corallimorph-Dominated Reef Associated with a Shipwreck on Palmyra Atoll

Coral reefs can undergo relatively rapid changes in the dominant biota, a phenomenon referred to as phase shift. Various reasons have been proposed to explain this phenomenon including increased human disturbance, pollution, or changes in coral reef biota that serve a major ecological function such as depletion of grazers. However, pinpointing the actual factors potentially responsible can be problematic. Here we show a phase shift from coral to the corallimorpharian Rhodactis howesii associated with a long line vessel that wrecked in 1991 on an isolated atoll (Palmyra) in the central Pacific Ocean. We documented high densities of R. howesii near the ship that progressively decreased with distance from the ship whereas R. howesii were rare to absent in other parts of the atoll. We also confirmed high densities of R. howesii around several buoys recently installed on the atoll in 2001. This is the first time that a phase shift on a coral reef has been unambiguously associated with man-made structures. This association was made, in part, because of the remoteness of Palmyra and its recent history of minimal human habitation or impact. Phase shifts can have long-term negative ramification for coral reefs, and eradication of organisms responsible for phase shifts in marine ecosystems can be difficult, particularly if such organisms cover a large area. The extensive R. howesii invasion and subsequent loss of coral reef habitat at Palmyra also highlights the importance of rapid removal of shipwrecks on corals reefs to mitigate the potential of reef overgrowth by invasives