Comparing environmental impacts of deep-seabed and land-based mining: A defensible framework.

The crises of climate change and biodiversity loss are interlinked and must be addressed jointly. A proposed solution for reducing reliance on fossil fuels, and thus mitigating climate change, is the transition from conventional combustion-engine to electric vehicles. This transition currently requires additional mineral resources, such as nickel and cobalt used in car batteries, presently obtained from land-based mines. Most options to meet this demand are associated with some biodiversity loss. One proposal is to mine the deep seabed, a vast, relatively pristine and mostly unexplored region of our planet. Few comparisons of environmental impacts of solely expanding land-based mining versus extending mining to the deep seabed for the additional resources exist and for biodiversity only qualitative. Here, we present a framework that facilitates a holistic comparison of relative ecosystem impacts by mining, using empirical data from relevant environmental metrics. This framework (Environmental Impact Wheel) includes a suite of physicochemical and biological components, rather than a few selected metrics, surrogates, or proxies. It is modified from the "recovery wheel" presented in the International Standards for the Practice of Ecological Restoration to address impacts rather than recovery. The wheel includes six attributes (physical condition, community composition, structural diversity, ecosystem function, external exchanges and absence of threats). Each has 3-5 sub attributes, in turn measured with several indicators. The framework includes five steps: (1) identifying geographic scope; (2) identifying relevant spatiotemporal scales; (3) selecting relevant indicators for each sub-attribute; (4) aggregating changes in indicators to scores; and (5) generating Environmental Impact Wheels for targeted comparisons. To move forward comparisons of land-based with deep seabed mining, thresholds of the indicators that reflect the range in severity of environmental impacts are needed. Indicators should be based on clearly articulated environmental goals, with objectives and targets that are specific, measurable, achievable, relevant, and time bound.

Subchronic treatment with phencyclidine in adolescence leads to impaired exploratory behavior in adult rats without altering social interaction or N-methyl-D-aspartate receptor binding levels.

Although both the onset of schizophrenia and human phencyclidine (PCP) abuse typically present within the interval from adolescence to early adulthood, the majority of preclinical research employing the PCP model of schizophrenia has been conducted on neonatal or adult animals. The present study was designed to evaluate the behavioral and neurochemical sequelae of subchronic exposure to PCP in adolescence. Male 35-42-day-old Sprague Dawley rats were subcutaneously administered either saline (10 ml · kg(-1) ) or PCP hydrochloride (10 mg · kg(-1) ) once daily for a period of 14 days (n = 6/group). The animals were allowed to withdraw from treatment for 2 weeks, and their social and exploratory behaviors were subsequently assessed in adulthood by using the social interaction test. To examine the effects of adolescent PCP administration on the regulation of N-methyl-D-aspartate receptors (NMDARs), quantitative autoradiography was performed on brain sections of adult, control and PCP-withdrawn rats by using 20 nM (3) H-MK-801. Prior subchronic exposure to PCP in adolescence had no enduring effects on the reciprocal contact and noncontact social behavior of adult rats. Spontaneous rearing in response to the novel testing arena and time spent investigating its walls and floor were reduced in PCP-withdrawn animals compared with control. The long-term behavioral effects of PCP occurred in the absence of persistent deficits in spontaneous locomotion or self-grooming activity and were not mediated by altered NMDAR density. Our results document differential effects of adolescent PCP administration on the social and exploratory behaviors of adult rats, suggesting that distinct neurobiological mechanisms are involved in mediating these behaviors.

Decrease of D2 receptor binding but increase in D2-stimulated G-protein activation, dopamine transporter binding and behavioural sensitization in brains of mice treated with a chronic escalating dose 'binge' cocaine administration paradigm.

Understanding the neurobiology of the transition from initial drug use to excessive drug use has been a challenge in drug addiction. We examined the effect of chronic 'binge' escalating dose cocaine administration, which mimics human compulsive drug use, on behavioural responses and the dopaminergic system of mice and compared it with a chronic steady dose (3 x 15 mg/kg/day) 'binge' cocaine administration paradigm. Male C57BL/6J mice were injected with saline or cocaine in an escalating dose paradigm for 14 days. Locomotor and stereotypy activity were measured and quantitative autoradiographic mapping of D(1) and D(2) receptors, dopamine transporters and D(2)-stimulated [(35)S]GTPgammaS binding was performed in the brains of mice treated with this escalating and steady dose paradigm. An initial sensitization to the locomotor effects of cocaine followed by a dose-dependent increase in the duration of the locomotor effect of cocaine was observed in the escalating but not the steady dose paradigm. Sensitization to the stereotypy effect of cocaine and an increase in cocaine-induced stereotypy score was observed from 3 x 20 to 3 x 25 mg/kg/day cocaine. There was a significant decrease in D(2) receptor density, but an increase in D(2)-stimulated G-protein activity and dopamine transporter density in the striatum of cocaine-treated mice, which was not observed in our steady dose paradigm. Our results document that chronic 'binge' escalating dose cocaine treatment triggers profound behavioural and neurochemical changes in the dopaminergic system, which might underlie the transition from drug use to compulsive drug use associated with addiction, which is a process of escalation.

Effect of aging and Alzheimer's disease-like pathology on brain monoamines in mice.

Aging is the greatest single risk factor of the neurodegenerative disorder Alzheimer's disease (AD). The monoaminergic system, including serotonin (5-HT), dopamine (DA) and noradrenaline (NA) modulates cognition, which is affected in AD. Changes in monoamine levels have been observed in AD, but these can both be age- and/or disease-related. We examined whether brain monoamine levels change as part of physiological aging and/or AD-like disease in APPSWE/PS1ΔE9 (APP/PS1) transgenic mice. The neocortex, hippocampus, striatum, brainstem and cerebellum of 6-, 12-, 18- and 24-month-old B6C3 wild-type (WT) mice and of 18-month old APP/PS1 and WT mice were analysed for 5-HT, DA and NA contents by high pressure liquid chromatography (HPLC), along with neocortex from 14-month-old APP/PS1 and WT mice. While, we observed no aging effect in WT mice, we detected region-specific changes in the levels of all monoamines in 18-month-old transgenic compared with WT mice. This included reductions in 5-HT (-30%), DA (-47%) and NA (-32%) levels in the neocortex and increases of 5-HT in the brainstem (+18%). No changes were observed in any of the monoamines in the neocortex from 14-month-old APP/PS1 mice. In combination, these findings indicate that aging alone is not sufficient to affect brain monoamine levels, unlike the APPSWE/PS1ΔE9 genotype.

Modelling of industrial conveyorized applicators using higher order vector finite elements.

This paper presents a finite element time domain method for the solution of Maxwell's equations in microwave heating applicators using first and second order vector finite elements. Results are compared with experimental data and it has been shown that second order vector finite elements have many advantages over first order elements. Capitalising on the high accuracy and low computational cost attainable by higher order elements, an industrial conveyor belt system is numerically analyzed.

The AMPERE association and trends in its biennial conferences.

AMPERE (Association for Microwave Power in Europe for Research and Education) is a "European" non-profit association devoted to the promotion of microwave and radio frequency heating techniques for research and industrial applications. Despite the fact that AMPERE is a European association, it has a world-wide membership which comprises industrialists, academics, researchers and consultants. This brief paper focuses on the trends in the subject matter and activities in the biennial AMPERE conferences held in Europe since 1986.

Simulation of RF coronas using the FE-FCT method.

The precursor of arcs in radio frequency heating systems, namely corona discharges, are examined numerically in this paper, using the finite element-flux corrected transport technique. A point-plane configuration is used as a first approximation for a radio frequency applicator and the effects of the operating frequency and pressure on the current output, charge densities, corona onset voltage and light output are investigated. It was found that an increase in the operating frequency around the radio frequency part of the spectrum, resulted in an increase in the corona onset voltage, which accounts for the less arc-prone behavior of microwave systems. Also, a decrease in the pressure resulted in a reduction of the corona onset voltage, and thus the increased possibility of arc formation in radio frequency systems operating under vacuum conditions.

Determination of resonant modes of RF heating systems using eigenvalue analysis.

In this paper the resonant modes of a radio frequency industrial heating applicator system are determined numerically. This is carried out using a finite element eigenvalue calculation of the electric field of the system. Both the complex linear and nonlinear forms of the generalized large sparse eigenproblem are solved, the latter being obligatory when material properties are frequency-dependent. The basis is the Implicity Restarted Arnoldi/Lanczos Methods which can be used to calculate the multiple resonant modes occurring in the operating frequency range of interest. Once the resonant modes of a specific system have been obtained, an electric equivalent circuit model can be derived. The numerical results presented are compared to experimental measurements carried out on a prototype experimental system showing good agreement.

Application of the resistive sheet in finite element microwave heating systems.

The use of the resistive sheet for characterizing thin metallic films is presented in a microwave heating context. A finite edge element formulation is used to include the resistive sheet surface integral in both the frequency and time domains. The properties of the resistive sheet are compared with analytical expressions for the reflection, transmission and absorption coefficients and a correction factor is suggested to improve the accuracy of the numerical implementation. Results are presented for single and multimode systems.

Parallel computing in microwave heating analysis.

The use of parallel computing in the finite element analysis of microwave heating applicators is discussed. Numerical results for a multiple feed cavity at 896 MHz and a cavity with a mode stirrer at 2.45 GHz are presented, and it is shown that for the two structures parallelism is most effectively introduced at different levels in the analysis.

The effect of wall losses in the numerical simulation of microwave heating problems.

A study is made into the numerical modeling of wall losses for a microwave heating application. It makes use of a surface integral term for both a frequency and time domain finite edge element formulation in order to model the wall impedance of the enclosed microwave cavity. The paper describes how the surface element matrix of the complex wall impedance is combined with the matrix formulation. The results are checked against analytical expressions for a single mode resonant cavity. An analysis on the effect of lossy walls is provided using four low-loss material insertions over a range of surface conductivities.

Switch mode power supply for microwave heating based on the Boucherot effect.

This paper describes a new self-resonating switch-mode power-supply for driving CW magnetrons, based on the Boucherot effect. A detailed circuit analysis is given and its performance is evaluated for an 800 W/2450 MHz magnetron, whilst work at high power driving a magnetron up to 40 kW is reported. A comparison of the supply with the conventional power-supply used in microwave ovens is made and the principal features of the new design are found to be: low energy dissipation under short-circuit conditions, low ripple current and voltage waveforms that result in more precise control in the range 20-100% of rated power, high efficiencies and small size and weight.

Numerical modeling for RF and microwave heating using FE comes of age.

This paper gives a brief resume of the numerical work carried out over the past decade at the Electricity Utilisation Group usingfinite elements for the characterization of RF and microwave heating systems. Maxwell's equations are solved in 3D while for coronas the Poisson's and particle continuity equations are solved in 2D. In addition work on modeling thin films and the use of parallel computing describes the latest work to emanate from the group.

The stereotypy-inducing and OCD-like effects of chronic 'binge' cocaine are modulated by distinct subtypes of nicotinic acetylcholine receptors.

BACKGROUND AND PURPOSE: High rates of cigarette smoking occur in cocaine-dependent individuals, reflecting an involvement of nicotinic acetylcholine receptors (nAChRs) in cocaine-elicited behaviour. This study was designed to assess the contribution of different nAChR subtypes to the behavioural and neurochemical effects of chronic cocaine treatment. EXPERIMENTAL APPROACH: Cocaine (15 mg·kg(-1) , i.p.) was administered to male C57BL/6J mice in a chronic 'binge' paradigm, with and without the coadministration of the α7 preferring nAChR antagonist methyllycaconitine (MLA; 5 mg·kg(-1) , i.p.) or the ß2* nAChR antagonist dihydro-ß-erythroidine (DHßE; 2 mg·kg(-1) , i.p.). Quantitative autoradiography was used to examine the effect of cocaine exposure on α7 and α4ß2* nAChRs, and on the high-affinity choline transporter. KEY RESULTS: MLA+cocaine administration induced an intense self-grooming behaviour, indicating a likely role for α7 nAChRs in modulating this anxiogenic, compulsive-like effect of cocaine. In the major island of Calleja, a key area of action for neuroleptics, MLA+cocaine reduced choline transporter binding compared with cocaine (with or without DHßE) administration. DHßE treatment prevented the induction of stereotypy sensitisation to cocaine but prolonged locomotor sensitisation, implicating heteromeric ß2* nAChRs in the neuroadaptations mediating cocaine-induced behavioural sensitisation. 'Binge' cocaine treatment region-specifically increased α4ß2* nAChR binding in the midbrain dopaminergic regions: ventral tegmental area and substantia nigra pars compacta. CONCLUSIONS AND IMPLICATIONS: We have shown a differential, subtype-selective, contribution of nAChRs to the behavioural and neurochemical sequelae of chronic cocaine administration. These data support the clinical utility of targeting specific nAChR subtypes for the alleviation of cocaine-abuse symptomatology.

Increased desensitization of dopamine D2 receptor-mediated response in the ventral tegmental area in the absence of adenosine A(2A) receptors.

G-protein coupled receptors interact to provide additional regulatory mechanisms for neurotransmitter signaling. Adenosine A(2A) receptors are expressed at a high density in striatal neurons, where they closely interact with dopamine D2 receptors and modulate effects of dopamine and responses to psychostimulants. A(2A) receptors are expressed at much lower densities in other forebrain neurons but play a more prominent yet opposing role to striatal receptors in response to psychostimulants in mice. It is, therefore, possible that A(2A) receptors expressed at low levels elsewhere in the brain may also regulate neurotransmitter systems and modulate neuronal functions. Dopamine D2 receptors play an important role in autoinhibition of neuronal firing in dopamine neurons of the ventral tegmental area (VTA) and dopamine release in other brain areas. Here, we examined the effect of A(2A) receptor deletion on D2 receptor-mediated inhibition of neuronal firing in dopamine neurons in the VTA. Spontaneous activity of dopamine neurons was recorded in midbrain slices, and concentration-dependent effects of the dopamine D2 receptor agonist, quinpirole, was compared between wild-type and A(2A) knockout mice. The potency of quinpirole applied in single concentrations and the expression of D2 receptors were not altered in the VTA of the knockout mice. However, quinpirole applied in stepwise escalating concentrations caused significantly reduced maximal inhibition in A(2A) knockout mice, indicating an enhanced agonist-induced desensitization of D2 receptors in the absence of A(2A) receptors. The A(2A) receptor agonist, CGS21680, did not exert any effect on dopamine neuron firing or response to quinpirole, revealing a novel non-pharmacological interaction between adenosine A(2A) receptors and dopaminergic neurotransmission in midbrain dopamine neurons. Altered D2 receptor desensitization may result in changes in dopamine neuron firing rate and pattern and dopamine release in other brain areas in response to persistent dopamine release and administration of psychostimulants.

Variation in maxillary and mandibular molar and incisor vertical dimension in 12-year-old subjects with excess, normal, and short lower anterior face height.

Maxillary and mandibular molar and incisor vertical dimensions were evaluated in subjects who had excessive, normal, and short lower anterior face height in relation to upper face height. Sexual dimorphism was also investigated. The dentoalveolar heights were compared between Class I and Class II, dental and skeletal malocclusions. The sample was drawn from the Burlington Growth Centre sample and consisted of 188 male and 156 female subjects at age 12 years, for whom lateral head films were available. This sample was classified into excessive, normal, and short lower anterior face height, using the ratio upper anterior face height/lower anterior face height (UAFH/LAFH). The results showed that the dentoalveolar heights are significantly different between faces with excessive, normal, and short lower anterior face heights, except for the lower posterior dental height, which showed no difference between short and normal lower anterior face height subjects. All dentoalveolar heights are larger for male subjects except for the upper posterior dental height. Dentoalveolar heights are similar between Class I and Class II dental and skeletal malocclusions. The upper teeth present a higher correlation to the UAFH/LAFH ratio than the lower teeth. Stepwise regression analysis shows that 22% of the variation in the ratio is explained by the maxillary and mandibular molars and 41% is explained by the maxillary and mandibular incisors.

A report of orthodontic undergraduate education in two dental schools: Toronto, Canada and Liverpool, England.

The undergraduate orthodontic courses at Toronto and Liverpool are compared. Each course comprises more than 250 hours of teaching and within that, more than 100 hours involve clinical tuition. Both courses contain laboratory modules for the teaching of removable and fixed appliance technique. Undergraduates treat their own patients with both simple and complex appliances, within their clinical training period which extends over at least 2 years. Liverpool undergraduates treat more patients per student than their counterparts in Toronto (P < 0.05). During the third year of study, the clinical experience of the Liverpool students (P < 0.001) is made up of a greater proportion of patients treated with removable appliances. In both centres, senior students treat patients with a greater preponderance of fixed appliance techniques and two-arch treatments.

The influence of functional appliance therapy on glenoid fossa remodeling.

This study investigates the remodeling changes in the condyle and glenoid fossa following a period of progressively activated and continuously maintained mandibular advancement using the Herbst appliance. Progressive mandibular advancement was achieved by adding stops to the telescopic arms of the appliance, with the total activation reaching 7.0 to 10.0 mm, dependent upon the length of the treatment phase. This mandibular advancement produced extensive remodeling and anterior relocation of the glenoid fossa, which contributed to anterior mandibular positioning and altered jaw relationships.

Use of a facemask to protect the intra-oral area in cynomolgus monkeys.

A custom fiberglass facemask was designed for cynomolgus monkeys to protect an orthodontic appliance. The mask was constructed from impressions and models made of the animal's head. It prevented the fingers from entering the mouth to dislodge the intra-oral appliances. The facemask permitted normal physical activity, eating, and drinking.