1,385 research outputs found
Molecular biomarkers and toxic consequences of impact by organic pollution in aquatic organisms
Organic contaminants are readily bioaccumulated by aquatic organisms. Exposure to and toxic effects of contaminants can be measured in terms of the biochemical responses of the organisms (i.e. molecular biomarkers). The hepatic biotransformation enzyme cytochrome P4501A (CYP1A) in vertebrates is specifically induced by organic contaminants such as aromatic hydrocarbons, PCBs and dioxins, and is involved in chemical carcinogenesis via catalysis of the covalent binding of organic contaminants to DNA (DNA-adducts). Hepatic CYP1A induction has been used extensively and successfully as a biomarker of organic contaminant exposure in fish. Fewer but equally encouraging studies in fish have used hepatic bulky, hydrophobic DNA-adducts as biomarkers of organic contaminant damage. Much less is known of the situation in marine invertebrates, but a CYPlA-like enzyme with limited inducibility and some potential for biomarker application is indicated. Stimulation of reactive oxygen species (ROS) production is another potential mechanism of organic contaminant-mediated DNA and other damage in aquatic organisms. A combination of antioxidant (enzymes, scavengers) and pro-oxidant (oxidised DNA bases, lipid peroxidation) measurements may have potential as a biomarker of organic contaminant exposure (particularly those chemicals which do not induce CYP1A) and/or oxidative stress, but more studies are required. Both CYP1A- and ROS-mediated toxicity are indicated to result in higher order deleterious effects, including cancer and other aspects of animal fitness
Cultivating humanity?
Various studies suggest that major changes are required in predominant human values during the next two generations, to ensure politically and environmentally sustainable societies and a sustainable global order: away from consumerism to a focus on quality of life; away from a certain type of possessive individualism, towards more human solidarity; and away from an assumption of domination of nature, towards a greater ecological sensitivity. The paper reviews evidence on the scale of these challenges. Second, it analyses their implications and the possibilities of change at personal, societal and global levels, with special reference to education and the respective roles and mutual entanglement of personal change and system change. Thirdly, it discusses possible lessons and contributions of internationally oriented postgraduate education, drawing some suggestions from experience in the International Institute of Social Studies in The Hague
Opportunities for integrated pest management to control the poultry red mite, Dermanyssus gallinae
Dermanyssus gallinae is the most economically important ectoparasite of laying hens in Europe. Control of D. gallinae is already hampered by issues of pesticide resistance and product withdrawal and, with the prohibition of conventional cages in 2012 and the resulting switch to more structurally complex housing which favours red mite, the importance of managing this pest will increase. Integrated Pest Management (IPM), as often employed in agricultural pest control, may be a way to address these issues where a combination of different novel control methods could be used with/without conventional management techniques to provide a synergistic and more efficacious effect. Work at in our laboratory has shown that essential oils including thyme and garlic may act as effective D. gallinae repellents and acaricides, whilst preliminary vaccine studies have demonstrated a significant increase in mite mortality in vitro using concealed antigens. Work elsewhere 27 has considered predators and fungi for D. gallinae control and other husbandry techniques such as manipulating temperature and lighting regimes in poultry units. This paper will review the available and emerging techniques for D. gallinae control and discuss which techniques might be suitable for inclusion in an integrated management programme (e.g. synthetic acaricides and diatomaceous earths)
Mesonic Form Factors
We have started a program to compute the electromagnetic form factors of
mesons. We discuss the techniques used to compute the pion form factor and
present preliminary results computed with domain wall valence fermions on MILC
asqtad lattices, as well as Wilson fermions on quenched lattices. These methods
can easily be extended to rho-to-gamma-pi transition form factors.Comment: 7 pages, 6 figures, Workshop on Lattice Hadron Physics 2003 (LHP2003
Hispania, la leyenda: The Myth of Viriatus’ Struggle Transfigured for Television
“Hispania, la leyenda” is the first Spanish attempt to represent on screen the Roman occupation of the Iberian Peninsula and the resistance led by Viriatus. This paper analyzes the TV series in terms of two key features that define it as a historical recreation that repackages the foundational myth as an adventure story with patriotic overtones: 1) the appropriation of a key figure in Portuguese culture to build a notion of Hispanic identity; and 2) the analogy with the Napoleonic occupation and War of Independence, amply evoked in the film and television of the dictatorship and early democracy as well as in the productions made for the recent bicentennial commemorations. -------------------------------------------------------------------------------------- Hispania, la leyenda constituye el primer intento español de llevar a la pantalla la ocupación romana de la Península Ibérica y la resistencia liderada por Viriato. Nuestro trabajo analiza la serie televisiva atendiendo a dos elementos que la determinan como proyecto de recreación histórica, finalmente fallido, que aprovecha el mito fundacional en una estructura de ficción de aventuras con tintes patrióticos: 1) la apropiación de una figura con mayor raigambre en la cultura portuguesa para, eludiendo este factor, elaborar una idea de identidad de lo hispano; y 2) la analogía con la ocupación napoleónica y Guerra de la Independencia, que sí cuentan con tradición en el cine y la televisión tanto de la dictadura como de la era constitucional, y cuyo segundo centenario se conmemora en los mismos años de producción del programa
X-ray Reflection By Photoionized Accretion Discs
We present the results of reflection calculations that treat the relevant
physics with a minimum of assumptions. The temperature and ionization structure
of the top five Thomson depths of an illuminated disc are calculated while also
demanding that the atmosphere is in hydrostatic equilibrium. In agreement with
Nayakshin, Kazanas & Kallman, we find that there is a rapid transition from hot
to cold material in the illuminated layer. However, the transition is usually
not sharp so that often we find a small but finite region in Thomson depth
where there is a stable temperature zone at T \sim 2 x 10^{6} K due to
photoelectric heating from recombining ions. As a result, the reflection
spectra often exhibit strong features from partially-ionized material,
including helium-like Fe K lines and edges. We find that due to the highly
ionized features in the spectra these models have difficulty correctly
parameterizing the new reflection spectra. There is evidence for a spurious
correlation in the ASCA energy range, where is the reflection
fraction for a power-law continuum of index , confirming the suggestion
of Done & Nayakshin that at least part of the R-Gamma correlation reported by
Zdziarski, Lubinski & Smith for Seyfert galaxies and X-ray binaries might be
due to ionization effects. Although many of the reflection spectra show strong
ionized features, these are not typically observed in most Seyfert and quasar
X-ray spectra.Comment: 16 pages, accepted by MNRAS, Fig. 8 is in colour Figures and tables
changed by a code update. Conclusions unchange
3D printed fluidics with embedded analytic functionality for automated reaction optimisation
Additive manufacturing or ‘3D printing’ is being developed as a novel manufacturing process for the production of bespoke micro- and milliscale fluidic devices. When coupled with online monitoring and optimisation software, this offers an advanced, customised method for performing automated chemical synthesis. This paper reports the use of two additive manufacturing processes, stereolithography and selective laser melting, to create multifunctional fluidic devices with embedded reaction monitoring capability. The selectively laser melted parts are the first published examples of multifunctional 3D printed metal fluidic devices. These devices allow high temperature and pressure chemistry to be performed in solvent systems destructive to the majority of devices manufactured via stereolithography, polymer jetting and fused deposition modelling processes previously utilised for this application. These devices were integrated with commercially available flow chemistry, chromatographic and spectroscopic analysis equipment, allowing automated online and inline optimisation of the reaction medium. This set-up allowed the optimisation of two reactions, a ketone functional group interconversion and a fused polycyclic heterocycle formation, via spectroscopic and chromatographic analysis
The temporal dynamics of Arc expression regulate cognitive flexibility
YesNeuronal activity regulates the transcription and
translation of the immediate-early gene Arc/Arg3.1,
a key mediator of synaptic plasticity. Proteasomedependent
degradation of Arc tightly limits its
temporal expression, yet the significance of this
regulation remains unknown. We disrupted the temporal
control of Arc degradation by creating an Arc
knockin mouse (ArcKR) where the predominant Arc
ubiquitination sites were mutated. ArcKR mice had
intact spatial learning but showed specific deficits
in selecting an optimal strategy during reversal
learning. This cognitive inflexibility was coupled to
changes in Arc mRNA and protein expression resulting
in a reduced threshold to induce mGluR-LTD and
enhanced mGluR-LTD amplitude. These findings
show that the abnormal persistence of Arc protein
limits the dynamic range of Arc signaling pathways
specifically during reversal learning. Our work
illuminates how the precise temporal control of activity-dependent
molecules, such as Arc, regulates synaptic
plasticity and is crucial for cognition.Open access funded by Biotechnology and Biological Sciences Research Counci
Sera from young and older humans equally sustain proliferation and differentiation of human myoblasts
International audienceUsing a human primary muscle cell culture model the behavior of myoblasts (satellite cells) cultured in human serum obtained from either young or elderly individuals was studied. Serum was obtained from a total of 13 young (7 male and 6 females aged, 23-36 years) and 9 elderly (4 male and 5 females aged 69-84 years) subjects and used in a number of experiments. Myoblasts were extracted from human muscle biopsy samples taken from the vastus lateralis. In the first experiment myoblasts were isolated immediately after extraction from the biopsy in media containing human sera to examine its effects on the onset and progression of Ki67 and desmin expression. No effect of the age of the serum was observed at 3, 5 or 7 days of proliferation. In addition, cells that had been expanded initially in optimum myoblast growth medium (GM, containing foetal calf serum and additional growth factors) prior to culture in medium containing 15% human serum were studied. The proportion of proliferating muscle cells co expressing desmin and Ki67 antigens after 46 hours was again similar in the young and old serum conditions. Culturing these myoblasts in media containing 2% human serum to study their fusion and differentiation also resulted in no difference between young and old serum conditions in terms of the percentage of nuclei inside myosin heavy chain positive myotubes. Despite the variability of different samples of myoblasts, the age of the serum has no affect on the expression of any measured index
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