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Clearing
Kinds of Clearing Selected AbstractsLoss of phosphorus from soil in semi-arid northern Tanzania as a result of cropping: evidence from sequential extraction and 31P-NMR spectroscopyEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2000D. Solomon Summary In semi-arid northern Tanzania, the native woodland is being rapidly cleared and replaced by low input agriculture. This has resulted in pronounced environmental degradation, and in particular loss of phosphorus (P) from the soil. We have used sequential extraction and 31P-NMR to investigate the effects of land use changes, i.e. native woodland, degraded woodland, cultivation for 3 and 15 years and homestead fields where manure was applied, on the amount and structural composition of P in this soil. Clearing and continuous cultivation reduced both organic and inorganic P in the soil. The difference in the amount of organic P from the bulk soil of the fields cultivated for 3 and 15 years was not statistically significant (P <,0.05), suggesting that most of the depletion in organic P occurred during the first 3 years of cultivation. By contrast, in the homesteads, there was much organic and inorganic P in the soil. The 31P-NMR revealed that cultivation resulted in a 53% depletion of orthophosphate diester P, whereas only a 30% and 39% reduction of orthophosphate monoester P was found in the bulk soil after 3 and 15 years of cultivation, respectively. These results concur with the suggestion that diester P constitutes more easily mineralizable forms of organic P in soil than does monoester P. Our 31P-NMR also showed that 70% of the inorganic orthophosphate P was depleted from the coarse and fine sand separates as a result of cultivation. The influence of clearing and subsequent cropping on the amount and forms of P was more pronounced in the coarse and fine sand than in the silt and clay, stressing the importance of particle size and chemical properties such as organic matter and oxides in the availability of P in this soil. Our results show that the current low input agricultural practice is not sustainable, and that practices must be developed to combat the ongoing degradation of the soil. A combined use of available organic materials such as animal manure with the judicious use of inorganic fertilizers can replenish the soil's fertility. [source] Patterns and Determinants of Historical Woodland Clearing in Central-Western New South Wales, AustraliaGEOGRAPHICAL RESEARCH, Issue 4 2007MICHAEL BEDWARD Abstract We consider the history of woodland clearing in central western New South Wales, Australia, which has led to the present highly cleared and fragmented landscape. A combined approach is used examining available historical land-use data and using regression analysis to relate the pattern of cleared and wooded areas in the recent landscape to environmental variables, taking into account the contagious nature of clearing. We also ask whether it would be possible to apply a simple simulation modelling approach to reconstruct a credible historical sequence of clearing in the study area. The historical data indicate that annual clearing rates have varied substantially in the study area and selective tree removal (ringbarking and thinning) has been common. These findings make it unlikely that a simple simulation approach would replicate the spatial and temporal sequence of woodland loss. Our regression results show that clearing patterns can be related to environmental variables, particularly annual rainfall and estimated pre-European vegetation type, but that patterns are dominated by contagion. [source] Treatment of actinic keratoses with birch bark extract: a pilot studyJOURNAL DER DEUTSCHEN DERMATOLOGISCHEN GESELLSCHAFT, Issue 2 2006Constance Huyke aktinische Keratosen; Betulinsäure; Betulin; Oleanolsäure Summary Background: Birch bark contains a variety of apoptosis-inducing and anti-inflammatory substances such as betulinic acid, betulin, oleanolic acid and lupeol. Therefore, birch bark extract may be effective in the treatment of actinic keratoses. To address this issue, a pilot study using a standardized birch bark ointment was performed. Methods: Twenty-eight patients with actinic keratoses were enrolled in this prospective, non-randomized pilot study. Fourteen patients were treated with birch bark ointment only; fourteen patients received a combination therapy with cryotherapy and birch bark ointment. Treatment response was assessed clinically after two months. Results: Clearing of more than 75 % of the lesions was seen in 79 % of the patients treated with birch bark ointment monotherapy. The response rate of the combined treatment modality was 93 %. Therapy with birch bark ointment was well tolerated. Conclusion: In this pilot study, a standardized birch bark extract was effective in the treatment of actinic keratoses. This therapy is easy to perform and it has no side effects. Birch bark ointment may be a new therapeutic option for actinic keratoses. Zusammenfassung Hintergrund: Birkenkork ist reich an Triterpenen (Betulin, Betulinsäure, Oleanolsäure, Lupeol, Erythrodiol), für die Apoptose induzierende und antientzündliche Wirkungen beschrieben sind. Deshalb könnte sich ein Extrakt aus Birkenkork für die Therapie von aktinischen Keratosen eignen. Mit der hier untersuchten Birkenkork-Creme liegt erstmals eine galenische Formulierung vor (Birkenkorkextrakt, pflanzliche Öle, Wasser), in der die Wirkstoffe des Birkenkorks in therapeutisch ausreichender Menge vorhanden sind. Methoden: Im Rahmen der prospektiven, nicht randomisierten Pilotstudie wurden 28 Patienten mit aktinischen Keratosen behandelt. 14 Patienten erhielten eine Creme mit Birkenkorkextrakt als Monotherapie, 14 Patienten wurden zusätzlich kryotherapeutisch behandelt. Die Birkenkork-Creme wurde von den Patienten zweimal täglich aufgetragen. Das klinische Ansprechen wurde nach zwei Monaten erfasst. Ergebnisse: Bei Behandlung mit Birkenkorkextrakt als Monotherapie zeigten 79 % der Patienten nach einem Beobachtungszeitraum von zwei Monaten eine klinische Abheilung von über 75 % der Läsionen. Bei der Kombinationsbehandlung mit Kryotherapie kam es bei 93 % der Patienten zu einem Ansprechen auf die Behandlung. Die Verträglichkeit der Birkenkork-Creme war in allen Fällen sehr gut. Schlussfolgerung: Im Rahmen dieser Pilotstudie zeigte die lokale Anwendung eines standardisierten Birkenkorkextraktes eine gute Wirksamkeit bei der Behandlung aktinischer Keratosen. Die Anwendung ist einfach und die Verträglichkeit sehr gut. Deshalb stellt Birkenkorkextrakt eine interessante neue Therapieoption für aktinische Keratosen dar. [source] Behandlung aktinischer Keratosen mit Birkenkorkextrakt: Eine PilotstudieJOURNAL DER DEUTSCHEN DERMATOLOGISCHEN GESELLSCHAFT, Issue 2 2006Constance Huyke aktinische Keratosen; Betulinsäure; Betulin; Oleanolsäure Summary Background: Birch bark contains a variety of apoptosis-inducing and anti-inflammatory substances such as betulinic acid, betulin, oleanolic acid and lupeol. Therefore, birch bark extract may be effective in the treatment of actinic keratoses. To address this issue, a pilot study using a standardized birch bark ointment was performed. Methods: Twenty-eight patients with actinic keratoses were enrolled in this prospective, non-randomized pilot study. Fourteen patients were treated with birch bark ointment only; fourteen patients received a combination therapy with cryotherapy and birch bark ointment. Treatment response was assessed clinically after two months. Results: Clearing of more than 75 % of the lesions was seen in 79 % of the patients treated with birch bark ointment monotherapy. The response rate of the combined treatment modality was 93 %. Therapy with birch bark ointment was well tolerated. Conclusion: In this pilot study, a standardized birch bark extract was effective in the treatment of actinic keratoses. This therapy is easy to perform and it has no side effects. Birch bark ointment may be a new therapeutic option for actinic keratoses. Zusammenfassung Hintergrund: Birkenkork ist reich an Triterpenen (Betulin, Betulinsäure, Oleanolsäure, Lupeol, Erythrodiol), für die Apoptose induzierende und antientzündliche Wirkungen beschrieben sind. Deshalb könnte sich ein Extrakt aus Birkenkork für die Therapie von aktinischen Keratosen eignen. Mit der hier untersuchten Birkenkork-Creme liegt erstmals eine galenische Formulierung vor (Birkenkorkextrakt, pflanzliche Öle, Wasser), in der die Wirkstoffe des Birkenkorks in therapeutisch ausreichender Menge vorhanden sind. Methoden: Im Rahmen der prospektiven, nicht randomisierten Pilotstudie wurden 28 Patienten mit aktinischen Keratosen behandelt. 14 Patienten erhielten eine Creme mit Birkenkorkextrakt als Monotherapie, 14 Patienten wurden zusätzlich kryotherapeutisch behandelt. Die Birkenkork-Creme wurde von den Patienten zweimal täglich aufgetragen. Das klinische Ansprechen wurde nach zwei Monaten erfasst. Ergebnisse: Bei Behandlung mit Birkenkorkextrakt als Monotherapie zeigten 79 % der Patienten nach einem Beobachtungszeitraum von zwei Monaten eine klinische Abheilung von über 75 % der Läsionen. Bei der Kombinationsbehandlung mit Kryotherapie kam es bei 93 % der Patienten zu einem Ansprechen auf die Behandlung. Die Verträglichkeit der Birkenkork-Creme war in allen Fällen sehr gut. Schlussfolgerung: Im Rahmen dieser Pilotstudie zeigte die lokale Anwendung eines standardisierten Birkenkorkextraktes eine gute Wirksamkeit bei der Behandlung aktinischer Keratosen. Die Anwendung ist einfach und die Verträglichkeit sehr gut. Deshalb stellt Birkenkorkextrakt eine interessante neue Therapieoption für aktinische Keratosen dar. [source] Check 21 update: How does it affect you?JOURNAL OF CORPORATE ACCOUNTING & FINANCE, Issue 5 2006Stephen R. Goldberg As readers may know, the Check Clearing for the 21st Century Act (Check 21) enabled electronic processing of checks. How do things look today, about two years after Check 21 went into effect? The authors briefly review the provisions of Check 21 and discuss the potential for fraud, along with the current implications for both banks and companies. © 2006 Wiley Periodicals, Inc. [source] Clearing Up the Right-of-Return ConfusionMIDDLE EAST POLICY, Issue 2 2001Jerome M. Segal [source] Refractory subacute cutaneous lupus erythematosus successfully treated with rituximabAUSTRALASIAN JOURNAL OF DERMATOLOGY, Issue 3 2009Violet Kieu ABSTRACT A 48-year-old woman presented with pruritic, scaly, annular plaques over her upper back and chest that were clinically, serologically and histologically characteristic of subacute cutaneous lupus erythematosus (SCLE). She failed to respond to conventional treatment, which included high-dose hydroxychloroquine, methotrexate, prednisolone, chloroquine, acitretin, thalidomide, dapsone and azathioprine. Subsequently treated with intravenous rituximab 375 mg/m2 weekly for 4 weeks, she remained on adjuvant oral hydrochloroquine 600 mg daily and topical clobetasol propionate 0.05% ointment as required. Clearing of annular plaques was noted 8 weeks after the initial course of rituximab. By 12 weeks there were no new lesions and only post-inflammatory hyperpigmentation remained. Both hyper- and hypopigmentation, which is more common, are consistent with SCLE lesion regression. Skin lesions recurred 11 months later; however, no further lesions occurred after re-introduction of rituximab therapy. The treatment was well tolerated. A maintenance regimen of rituximab, 375 mg/m2 every 8 weeks for 2 years, was commenced 3 months after completing the second course of treatment, with ongoing disease remission. Rituximab appears to have activity in refractory SCLE and clinical trials are required to further assess this potential therapy. [source] Possible Environmental Factors Underlying Amphibian Decline in Eastern Puerto Rico: Analysis of U.S. Government Data ArchivesCONSERVATION BIOLOGY, Issue 4 2001Robert F. Stallard I examined changes in environmental conditions by examining time-series data sets that extend back at least into the 1980s, a period when frog populations were declining. The data include forest cover; annual mean, minimum, and maximum daily temperature; annual rainfall; rain and stream chemistry; and atmospheric-dust transport. I examined satellite imagery and air-chemistry samples from a single National Aeronautics and Space Administration aircraft flight across the Caribbean showing patches of pollutants, described as thin sheets or lenses, in the lower troposphere. The main source of these pollutants appeared to be fires from land clearing and deforestation, primarily in Africa. Some pollutant concentrations were high and, in the case of ozone, approached health limits set for urban air. Urban pollution impinging on Puerto Rico, dust generation from Africa ( potential soil pathogens), and tropical forest burning ( gaseous pollutants) have all increased during the last three decades, overlapping the timing of amphibian declines in eastern Puerto Rico. None of the data sets pointed directly to changes so extreme that they might be considered a direct lethal cause of amphibian declines in Puerto Rico. More experimental research is required to link any of these environmental factors to this problem. Resumen: Las pasadas tres décadas han visto grandes disminuciones poblacionales de especies de anfibios en altas elevaciones de Puerto Rico oriental, una región única en los trópicos húmedos debido al grado de monitoreo ambiental que se ha llevado a cabo mediante los esfuerzos de las agencias de gobierno de los Estados Unidos. Examiné los cambios en condiciones ambientales mediante el análisis de datos de series de tiempo que se extienden hasta los 1980s, un periodo en el que las poblaciones de ranas estaban declinando. Los datos incluyen cobertura forestal; temperatura diaria media, mínima y máxima anual; precipitación anual; química de la lluvia y arroyos; y el transporte atmosférico de polvo. Examiné imágenes de satélite y muestras de química del aire obtenidos de un solo vuelo de una nave de la NASA a lo largo del Caribe que mostraba parches de contaminantes descritas como capas delgadas de lentes en la inferior troposfera. La mayor fuente de contaminantes parece ser los incendios de tierras clareadas y la deforestación, principalmente en África. Algunas concentraciones de contaminantes fueron altas y en el caso del ozono, se aproximó a los límites de salud establecidos para aire urbano. La contaminación urbana afectando a Puerto Rico, la generación de polvo en África ( patógenos del suelo potenciales) y la quema de bosque tropical (contaminantes gaseosos) han incrementado durante las últimas tres décadas, superponiéndose con el periodo en que oturrieron las disminuciones de anfibios en Puerto Rico oriental. Ninguno de estos conjuntos de datos señaló directamente hacia cambios tan extremos que debieran ser considerados como una causa letal directa de las disminuciones en Puerto Rico. Se requiere de más investigación experimental que vincule a estos factores ambientales con este problema. [source] Functions of glutamate transporters in cerebellar Purkinje cell synapsesACTA PHYSIOLOGICA, Issue 1 2009Y. Takayasu Abstract Glutamate transporters play a critical role in the maintenance of low extracellular concentrations of glutamate, which prevents the overactivation of post-synaptic glutamate receptors. Four distinct glutamate transporters, GLAST/EAAT1, GLT-1/EAAT2, EAAC1/EAAT3 and EAAT4, are distributed in the molecular layer of the cerebellum, especially near glutamatergic synapses in Purkinje cells (PCs). This review summarizes the current knowledge about the differential roles of these transporters at excitatory synapses of PCs. Data come predominantly from electrophysiological experiments in mutant mice that are deficient in each of these transporter genes. GLAST expressed in Bergmann glia contributes to the clearing of the majority of glutamate that floods out of the synaptic cleft immediately after transmitter release from the climbing fibre (CF) and parallel fibre (PF) terminals. It is indispensable to maintain a one-to-one relationship in synaptic transmission at the CF synapses by preventing transcellular glutamate spillover. GLT-1 plays a similar but minor role in the uptake of glutamate as GLAST. Although the loss of neither GLAST nor GLT-1 affects cerebellar morphology, the deletion of both GLAST and GLT-1 genes causes the death of the mutant animal and hinders the folium formation of the cerebellum. EAAT4 removes the low concentrations of glutamate that escape from uptake by glial transporters, preventing the transmitter from spilling over into neighbouring synapses. It also regulates the activation of metabotropic glutamate receptor 1 (mGluR1) in perisynaptic regions at PF synapses, which in turn affects mGluR1-mediated events including slow EPSCs and long-term depression. No change in synaptic function is detected in mice that are deficient in EAAC1. [source] The Treatment of Melasma with Fractional Photothermolysis: A Pilot StudyDERMATOLOGIC SURGERY, Issue 12 2005Cameron K. Rokhsar MD Background. Melasma is a common pigmentary disorder that remains resistant to available therapies. Facial resurfacing with the pulsed CO2 laser has been reported successful but requires significant downtime, and there is a risk of adverse sequelae. Objective. To determine if melasma will respond to a new treatment paradigm, fractional resurfacing. Methods. Ten female patients (Fitzpatrick skin types III,V) who were unresponsive to previous treatment were treated at 1- to 2-week intervals with the Fraxel laser (Reliant Technologies, Palo Alto, CA, USA). Wavelengths of 1,535 and 1,550 nm were both used, and 6 to 12 mJ per microthermal zone with 2,000 to 3,500 mtz/cm2 were the treatment parameters. Four to six treatment sessions were performed. Responses were evaluated according to the percentage of lightening of original pigmentation. Two physicians evaluated the photographs, and each patient evaluated her own response. Results. The physician evaluation was that 60% of patients achieved 75 to 100% clearing and 30% had less than 25% improvement. The patients' evaluations agreed, except for one patient, who graded herself as 50 to 75% improved as opposed to the physician grading of over 75%. There was one patient with postinflammatory hyperpigmentation and no patient with hypopigmentation. No downtime was necessary for wound healing. Conclusions. Fractional resurfacing affords a new treatment algorithm for the treatment of melasma that combines decreased risk and downtime with significant efficacy. This treatment modality deserves further exploration to maximize benefits. RELIANT technologies LOANED THE FRAXEL LASER FOR THE STUDY. RICHARD E. FITZPATRICK, MD, IS A PAID CONSULTANT FOR RELIANT AND A STOCKHOLDER. [source] Combined Therapy Using Q-Switched Ruby Laser and Bleaching Treatment With Tretinoin and Hydroquinone for Acquired Dermal MelanocytosisDERMATOLOGIC SURGERY, Issue 10 2003Akira Momosawa MD Background and objective. Acquired dermal melanocytosis (ADM; acquired bilateral nevus of Ota-like macules) is known for its recalcitrance compared with Nevus of Ota, and we assume that one of the reasons is a higher rate and degree of postinflammatory hyperpigmentation (PIH) seen after laser treatments. Methods. Topical bleaching treatment with 0.1% tretinoin aqueous gel and 5% hydroquinone ointment containing 7% lactic acid was initially performed (4 to 6 weeks) to discharge epidermal melanin. Subsequently, Q-switched ruby (QSR) laser was irradiated to eliminate dermal pigmentation. Both steps were repeated two to three times until patient satisfaction was obtained (usually at a 2-month interval for laser sessions). This treatment was performed in 19 patients with ADM. Skin biopsy was performed in six cases at baseline, after the bleaching pretreatment, and at the end of treatment. Results. All patients showed good to excellent clearing after two to three sessions of QSR laser treatments. The total treatment period ranged from 3 to 13 (mean of 8.3) months. PIH was observed in 10.5% of the cases. Histologically, epidermal hyperpigmentation was observed in all specimens and was dramatically improved by the topical bleaching pretreatment. Conclusion. QSR laser combined with the topical bleaching pretreatment appeared to treat ADM consistently with a low occurrence rate of PIH and lessen the number of laser sessions and total treatment period and may also be applied to any other lesions with both epidermal and dermal pigmentation. [source] "Ultraviolet spring" and the ecological consequences of catastrophic impactsECOLOGY LETTERS, Issue 2 2000Charles S. Cockell Asteroid and comet impacts cause ozone depletion. For the first time, we have quantified the photobiological characteristics of these events and speculate on some of the associated ecological consequences. Following the clearing of stratospheric dust after "impact winter", levels of damaging UVB radiation (280,315 nm) could increase by at least 100%, resulting in an "ultraviolet spring". Many of the taxa stressed by the cold and dark conditions of impact are the same that would be stressed by large increases in UVB radiation. Furthermore, depletion of dissolved organic carbon (DOC) by impact-induced acid rain would increase UVB penetrability into freshwater systems. Although an increase in UVB radiation is an attractive hypothesis for exacerbating the demise of land animals at the Cretaceous-Tertiary (K/T) boundary, e.g. dinosaurs, our calculations suggest the impact into rare sulphate-rich target rock may have prevented an ultraviolet spring in this case. If the K/T impact event had occurred in any other region on Earth, the stress to the biosphere would probably have been considerably greater. [source] Tospoviruses infecting vegetable crops in IsraelEPPO BULLETIN, Issue 2 2000A. Gera Symptoms of vein clearing, stem necrosis, curling, necrotic spots and rings on the leaves associated with infection by tomato spotted wilt tospovirus (TSWV) were documented among vegetable crops growing in commercial glasshouses and open fields in Israel. Plants exhibiting symptoms were collected, from 1994-01 to 1998-12. Among cultivated vegetable crops analysed for TSWV by ELISA, the following plants were found to be infected: tomato, capsicum, aubergine, lettuce, cabbage and cucumber. These incidences of the virus were all correlated with the occurrence in high population of Frankliniella occidentalis. Transmission of the virus from infected Datura stramonium to Petunia leaf discs, by F. occidentalis, was up to 26%. TSWV antigens were readily detected by ELISA in seeds harvested from naturally infected vegetable crops. However, we failed to show virus transmission to the progeny plants. Iris yellow spot tospovirus (IYSV) was detected in onion. High incidence of the disease was associated with large populations of Thrips tabaci. [source] Loss of phosphorus from soil in semi-arid northern Tanzania as a result of cropping: evidence from sequential extraction and 31P-NMR spectroscopyEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2000D. Solomon Summary In semi-arid northern Tanzania, the native woodland is being rapidly cleared and replaced by low input agriculture. This has resulted in pronounced environmental degradation, and in particular loss of phosphorus (P) from the soil. We have used sequential extraction and 31P-NMR to investigate the effects of land use changes, i.e. native woodland, degraded woodland, cultivation for 3 and 15 years and homestead fields where manure was applied, on the amount and structural composition of P in this soil. Clearing and continuous cultivation reduced both organic and inorganic P in the soil. The difference in the amount of organic P from the bulk soil of the fields cultivated for 3 and 15 years was not statistically significant (P <,0.05), suggesting that most of the depletion in organic P occurred during the first 3 years of cultivation. By contrast, in the homesteads, there was much organic and inorganic P in the soil. The 31P-NMR revealed that cultivation resulted in a 53% depletion of orthophosphate diester P, whereas only a 30% and 39% reduction of orthophosphate monoester P was found in the bulk soil after 3 and 15 years of cultivation, respectively. These results concur with the suggestion that diester P constitutes more easily mineralizable forms of organic P in soil than does monoester P. Our 31P-NMR also showed that 70% of the inorganic orthophosphate P was depleted from the coarse and fine sand separates as a result of cultivation. The influence of clearing and subsequent cropping on the amount and forms of P was more pronounced in the coarse and fine sand than in the silt and clay, stressing the importance of particle size and chemical properties such as organic matter and oxides in the availability of P in this soil. Our results show that the current low input agricultural practice is not sustainable, and that practices must be developed to combat the ongoing degradation of the soil. A combined use of available organic materials such as animal manure with the judicious use of inorganic fertilizers can replenish the soil's fertility. [source] Incorporating power system security into market-clearing of day-ahead joint energy and reserves auctionsEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 2 2010J. Aghaei Abstract This paper is intended to introduce a technique for incorporating system security into the clearing of day-ahead joint electricity markets, with particular emphasis on the voltage stability. A Multiobjective Mathematical Programming (MMP) formulation is implemented for provision of ancillary services (Automatic Generation Control or AGC, spinning, non-spinning, and operating reserves) as well as energy in simultaneous auctions by pool-based aggregated market scheme. In the proposed market-clearing structure, the security problem, as an important responsibility of ISO, is addressed and a nonlinear model is formulated and used as the extra objective functions of the optimization problem. Thus, in the MMP formulation of the market-clearing process, the objective functions (including augmented generation offer cost, overload index, voltage drop index, and loading margin) are optimized while meeting AC power flow constraints, system reserve requirements, and lost opportunity cost (LOC) considerations. The IEEE 24-bus Reliability Test System (RTS 24-bus) is used to demonstrate the performance of the proposed method. Copyright © 2008 John Wiley & Sons, Ltd. [source] Algorithmic challenges and current problems in market coupling regimesEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 4 2009Bernd Tersteegen Abstract Increasing cross-border trade at European borders has lead to the necessity of an efficient allocation of scarce cross-border capacities. Explicit auctions used to be the commonly applied auction method in the past at most borders, but due to the separation of the trade of electrical energy and the allocation of cross-border capacity, market inefficiencies arise. As a consequence, a trend toward a market coupling, which combines the trade of electrical energy with the allocation of cross-border capacity, can be observed across Europe. The most convincing approach to solve the complex optimization task associated with market couplings solves the problem by a maximization of the system-wide welfare based on a closed-form optimization. Practical experience shows that problems remain with such an approach. This paper thoroughly analyzes problems that may occur in market coupling regimes with a closed-form optimization. In this paper an extension of formerly presented formulations of the optimization problem is presented, which avoids the described problems. The extended formulation still assures practically feasible calculation times of far less than 10 minutes even for systems with up to 12 market areas. Further, a fair and transparent approach to determine feasible market clearing prices not neglecting the time and market coupling relationship between prices is shown in this paper and it is demonstrated that this approach does not lead to practically infeasible calculation times. Copyright © 2009 John Wiley & Sons, Ltd. [source] Can C4 plants contribute to aquatic food webs of subtropical streams?FRESHWATER BIOLOGY, Issue 6 2003Joanne E. Clapcott Summary 1. Recent stable isotope studies have revealed that C4 plants play a minor role in aquatic food webs, despite their often widespread distribution and production. We compared the breakdown of C3 (Eucalyptus) and C4 (Saccharum and Urochloa) plant litter in a small rain forest stream and used laboratory feeding experiments to determine their potential contribution to the aquatic food web. 2. All species of litter broke down at a fast rate in the stream, although Urochloa was significantly faster than Eucalyptus and Saccharum. This was consistent with the observed higher total organic nitrogen of Urochloa compared with the other two species. 3. The breakdown of Urochloa and Saccharum was, however, not associated with shredding invertebrates, which were poorly represented in leaf packs compared with the native Eucalyptus. The composition of the invertebrate fauna in packs of Urochloa quickly diverged from that of the other two species. 4. Feeding experiments using a common shredding aquatic insect Anisocentropus kirramus showed a distinct preference for Eucalyptus over both C4 species. Anisocentropus was observed to ingest C4 plant litter, particularly in the absence of other choices, and faecal material collected was clearly of C4 origin, as determined by stable isotope analysis. However, the stable carbon isotope values of the larvae did not shift away from their C3 signature in any of the feeding trials. 5. These data suggest that shredders avoid the consumption of C4 plants, in favour of native C3 species that appear to be of lower food quality (based on C : N ratios). Lower rates of consumption and lack of assimilation of C4 carbon also suggest that shredders may have a limited ability to process this material, even in the absence of alternative litter sources. Large scale clearing of forest and vegetation for C4 crops such as sugarcane will undoubtedly have important consequences for stream ecosystem function. [source] Quantifying uncertainty in estimates of C emissions from above-ground biomass due to historic land-use change to cropping in AustraliaGLOBAL CHANGE BIOLOGY, Issue 8 2001Damian J. Barrett Abstract Quantifying continental scale carbon emissions from the oxidation of above-ground plant biomass following land-use change (LUC) is made difficult by the lack of information on how much biomass was present prior to vegetation clearing and on the timing and location of historical LUC. The considerable spatial variability of vegetation and the uncertainty of this variability leads to difficulties in predicting biomass C density (tC ha,1) prior to LUC. The issue of quantifying uncertainties in the estimation of land based sources and sinks of CO2, and the feasibility of reducing these uncertainties by further sampling, is critical information required by governments world-wide for public policy development on climate change issues. A quantitative statistical approach is required to calculate confidence intervals (the level of certainty) of estimated cleared above-ground biomass. In this study, a set of high-quality observations of steady state above-ground biomass from relatively undisturbed ecological sites across the Australian continent was combined with vegetation, topographic, climatic and edaphic data sets within a Geographical Information System. A statistical model was developed from the data set of observations to predict potential biomass and the standard error of potential biomass for all 0.05° (approximately 5 × 5 km) land grid cells of the continent. In addition, the spatial autocorrelation of observations and residuals from the statistical model was examined. Finally, total C emissions due to historic LUC to cultivation and cropping were estimated by combining the statistical model with a data set of fractional cropland area per land grid cell, fAc (Ramankutty & Foley 1998). Total C emissions from loss of above-ground biomass due to cropping since European colonization of Australia was estimated to be 757 MtC. These estimates are an upper limit because the predicted steady state biomass may be less than the above-ground biomass immediately prior to LUC because of disturbance. The estimated standard error of total C emissions was calculated from the standard error of predicted biomass, the standard error of fAc and the spatial autocorrelation of biomass. However, quantitative estimates of the standard error of fAc were unavailable. Thus, two scenarios were developed to examine the effect of error in fAc on the error in total C emissions. In the first scenario, in which fAc was regarded as accurate (i.e. a coefficient of variation, CV, of fAc = 0.0), the 95% confidence interval of the continental C emissions was 379,1135 MtC. In the second scenario, a 50% error in estimated cropland area was assumed (a CV of fAc = 0.50) and the estimated confidence interval increased to between 350 and 1294 MtC. The CV of C emissions for these two scenarios was 25% and 29%. Thus, while accurate maps of land-use change contribute to decreasing uncertainty in C emissions from LUC, the major source of this uncertainty arises from the prediction accuracy of biomass C density. It is argued that, even with large sample numbers, the high cost of sampling biomass carbon may limit the uncertainty of above-ground biomass to about a CV of 25%. [source] Factors determining mammal species richness on habitat islands and isolates: habitat diversity, disturbance, species interactions and guild assembly rulesGLOBAL ECOLOGY, Issue 1 2000Barry J. Fox Abstract 1For over three decades the equilibrium theory of island biogeography has galvanized studies in ecological biogeography. Studies of oceanic islands and of natural habitat islands share some similarities to continental studies, particularly in developed regions where habitat fragmentation results from many land uses. Increasingly, remnant habitat is in the form of isolates created by the clearing and destruction of natural areas. Future evolution of a theory to predict patterns of species abundance may well come from the application of island biogeography to habitat fragments or isolates. 2In this paper we consider four factors other than area and isolation that influence the number and type of mammal species coexisting in one place: habitat diversity, habitat disturbance, species interactions and guild assembly rules. In all examples our data derive from mainland habitat, fragmented to differing degrees, with different levels of isolation. 3Habitat diversity is seen to be a good predictor of species richness. Increased levels of disturbance produce a relatively greater decrease in species richness on smaller than on larger isolates. Species interactions in the recolonization of highly disturbed sites, such as regenerating mined sites, is analogous to island colonization. Species replacement sequences in secondary successions indicate not just how many, but which species are included. Lastly, the complement of species established on islands, or in insular habitats, may be governed by guild assembly rules. These contributions may assist in taking a renewed theory into the new millennium. [source] Salinization of a Fresh Palaeo-Ground Water Resource by Enhanced RechargeGROUND WATER, Issue 1 2003F.W. Leaney Deterioration of fresh ground water resources caused by salinization is a growing issue in many arid and semi-arid parts of the world. We discuss here the incipient salinization of a 104 km2 area of fresh ground water (<3000 mg/L) in the semiarid Murray Basin of Australia caused by widespread changes in land use. Ground water 14C concentrations and unsaturated zone Cl soil water inventories indicate that the low salinity ground water originated mainly from palaeo-recharge during wet climatic periods more than 20,000 years ago. However, much of the soil water in the 20 to 60 m thick unsaturated zone throughout the area is generally saline (> 15,000 mg/L) because of relatively high evapotranspiration during the predominantly semiarid climate of the last 20,000 years. Widespread clearing of native vegetation over the last 100 years and replacement with crops and pastures leads to enhancement of recharge rates that progressively displace the saline soil-water from the unsaturated zone into the ground water. To quantify the impact of this new hydrologic regime, a one-dimensional model that simulates projected ground water salinities as a function of depth to ground water, recharge rates, and soil water salt inventory was developed. Results from the model suggest that, in some areas, the ground water salinity within the top 10 m of the water table is likely to increase by a factor of 2 to 6 during the next 100 years. Ground water quality will therefore potentially degrade beyond the point of usefulness well before extraction of the ground water exhausts the resource. [source] Jobs, Houses, and Trees: Changing Regional Structure, Local Land-Use Patterns, and Forest Cover in Southern IndianaGROWTH AND CHANGE, Issue 3 2003Darla K. Munroe Land-use and -cover change is a topic of increasing concern as interest in forest and agricultural land preservation grows. Urban and residential land use is quickly replacing extractive land use in southern Indiana. The interaction between land quality and urban growth pressures is also causing secondary forest growth and forest clearing to occur jointly in a complex spatial pattern. It is argued that similar processes fuel the abandonment of agricultural land leading to private forest regrowth, changes in topography and land quality, and declining real farm product prices. However, the impact of urban growth and development on forests depends more strongly on changes in both the residential housing and labor markets. Using location quotient analysis of aggregate employment patterns, and the relationship between regional labor market changes, the extent of private forest cover was examined from 1967 to 1998. Then an econometric model of land-use shares in forty southern Indiana counties was developed based on the net benefits to agriculture, forestland, and urban uses. To test the need to control explicitly for changes in residential demand and regional economic structure, a series of nested models was estimated. Some evidence was found that changing agricultural profitability is leading to private forest regrowth. It was also uncovered that the ratio of urban to forest land uses is better explained by incorporating measures of residential land value and industrial concentration than simply considering population density alone. [source] Hydrology and water quality in two mountain basins of the northeastern US: assessing baseline conditions and effects of ski area development,,HYDROLOGICAL PROCESSES, Issue 12 2007Beverley Wemple Abstract Mountain regions throughout the world face intense development pressures associated with recreational and tourism uses. Despite these pressures, much of the research on bio-geophysical impacts of humans in mountain regions has focused on the effects of natural resource extraction. This paper describes findings from the first 3 years of a study examining high elevation watershed processes in a region undergoing alpine resort development. Our study is designed as a paired-watershed experiment. The Ranch Brook watershed (9·6 km2) is a relatively pristine, forested watershed and serves as the undeveloped ,control' basin. West Branch (11·7 km2) encompasses an existing alpine ski resort, with approximately 17% of the basin occupied by ski trails and impervious surfaces, and an additional 7% slated for clearing and development. Here, we report results for water years 2001,2003 of streamflow and water quality dynamics for these watersheds. Precipitation increases significantly with elevation in the watersheds, and winter precipitation represents 36,46% of annual precipitation. Artificial snowmaking from water within West Branch watershed currently augments annual precipitation by only 3,4%. Water yield in the developed basin exceeded that in the control by 18,36%. Suspended sediment yield was more than two and a half times greater and fluxes of all major solutes were higher in the developed basin. Our study is the first to document the effects of existing ski area development on hydrology and water quality in the northeastern US and will serve as an important baseline for evaluating the effects of planned resort expansion activities in this area. Published in 2007 by John Wiley & Sons, Ltd. [source] A comparison between clearing and radiographic techniques in the study of the root-canal anatomy of maxillary first and second molarsINTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2004O. E. Omer Abstract Aim, To compare a clearing technique with conventional radiography in studying certain features of the root-canal system of maxillary right first and second molars. A secondary aim was to assess interexaminer agreement for these features using radiographs. Methodology, Eighty-three recently extracted permanent maxillary right first molars and 40 recently extracted maxillary right second molars from an Irish population were included. Standard periapical radiographs were taken from a buccolingual and mesiodistal direction. The specimens were then decoronated, demineralized in 10% hydrochloric acid for 8 days and then cleared using methyl salicylate. The cleared teeth were examined using a dissecting microscope (×20), and data relating to number of roots, canal type following Vertucci's classification, presence of lateral canals, presence of transverse anastomoses and position/number of apical foramina were collected. The radiographs were examined by two independent trained endodontists using an X-ray viewer and a magnifying lens (×2) in a dark room for the same features studied using the clearing technique. Results, The Kappa values for the agreement between the radiographic examiners A and B and the clearing technique and between the two examiners for the number of roots were 0.60, 0.64 and 0.53; for the root-canal type, 0.37, 0.41 and 0.42; for the number of roots with lateral canals, 0.21, 0.18 and 0.14; and for the transverse anastomoses, 0.29 for radiographic Examiner A. Radiographic Examiner B did not feel capable of accurately recognizing transverse anastomoses from the radiographs. For the position/number of apical foramina, the Kappa values were 0.33 and 0.24, respectively. In general, the Kappa values were low to modest for all comparisons. Conclusions, It is concluded that the agreement between the two radiographic examiners and the agreement between either radiographic examiner and the clearing technique were poor to moderate, indicating the limited value of radiographs alone when studying certain aspects of the root-canal system. [source] Treatment of late-stage Sézary syndrome with 2-ChlorodeoxyadenosineINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 6 2002Saskia A. Bouwhuis MD Background, 2-Chlorodeoxyadenosine (2-CdA), a purine adenosine analog, is safe and effective chemotherapy for patients with hairy cell leukemia and low-grade lymphomas. Adverse effects include neutropenia, lymphocytopenia, and infectious complications. Our objective was to evaluate the efficacy of 2-CdA (2,6 seven-day cycles) in the treatment of late-stage, recalcitrant Sézary syndrome. Methods, Retrospective review of medical records of six patients with Sézary syndrome who had received 2-CdA cycles at Mayo Clinic, Rochester between March 1995 and March 2000. Variables assessed from the records included improvement in global appearance, extent of erythroderma, size of lymph nodes, pruritus, and leukocyte, lymphocyte, and absolute Sézary cell counts. Results, Two patients, both with stage III Sézary syndrome, whose previous treatment consisted of only two modalities, responded well to the treatment, with moderate to total clearing of erythroderma and pruritus associated with a significant decrease in Sézary cell counts. The other four patients had only a partial response (one patient) or no response (three patients) to 2-CdA. The mortality rate was 50%. All three patients died of Staphylococcus aureus sepsis. However, only one patient was receiving 2-CdA treatment when he died. The other two patients died 8 and 9 weeks after the last 2-CdA cycle. This high mortality rate is attributed to infectious complications after 2-CdA treatment in patients with recalcitrant disease. Conclusion, 2-Chlorodeoxyadenosine shows efficacy in stage III Sézary syndrome, but it also carries a substantial risk of septic complications and mortality. It can be used if no other suitable alternatives are available. Caution should be exercised in all these patients regarding skin care and avoidance of infections or sepsis. [source] Elevation and forest clearing effects on foraging differ between surface , and subterranean , foraging army ants (Formicidae: Ecitoninae)JOURNAL OF ANIMAL ECOLOGY, Issue 1 2009Anjali Kumar Summary 1Forest fragmentation often results in a matrix of open areas mixed with patches of forest. Both biotic and abiotic factors can affect consumer species' ability to utilize the altered habitat, especially for species that range over large areas searching for prey. 2Army ants (Formicidae: Ecitoninae) are highly mobile top predators in terrestrial Neotropical ecosystems. Army ant foraging behaviour is influenced by forest clearing at lowland sites, and clearing can reduce army ant population persistence. 3Because high temperatures are implicated in hindering above-ground army ant foraging, we predicted that forest clearing effects on army ant foraging would be reduced at higher (cooler) elevations in montane forest. We also predicted that subterranean foraging, employed by some army ant species, would buffer them from the negative effects of forest clearing. 4We quantified the foraging rates of above-ground and underground foraging army ants at eight sites along an elevational gradient from 1090 to 1540 m a.s.l. We asked whether these two foraging strategies cause a difference in the ability of army ants to forage in open matrix areas relative to elevationally matched forested habitats, and whether elevation predicts open area vs. forest foraging rate differences. 5As predicted, army ants that forage above-ground had lower foraging rates in open areas, but the open area vs. forest difference declined with elevation. In contrast, underground foragers were not affected by habitat type, and underground foraging rates increased with elevation. Ground surface temperatures were higher in open areas than forested areas. Temperatures declined with elevation, and temperature differences between open and forested areas decreased with elevation. 6We conclude that army ants that forage above-ground may be restricted to forested areas due to a thermal tolerance threshold, but that they are released from this limitation at higher elevations. We further suggest that underground foraging permits some army ants to persist within modified landscapes. Our findings have implications for the effects of habitat modification and climate change on these top predators. [source] Twenty years of rest returns grazing potential, but not palatable plant diversity, to Karoo rangeland, South AfricaJOURNAL OF APPLIED ECOLOGY, Issue 4 2010Colleen L. Seymour Summary 1.,Up to 73% of the world's rangelands are degraded, and increasing demand for meat in developing countries and a growing human population are likely to exert even greater pressures on rangelands in the next 20,50 years. Restoration of rangeland grazing potential and resilience is therefore important, particularly in the face of climate change. 2.,We investigated the influence of past stocking rates (from 1910 to 1987), rainfall, and current grazing regimes (from 1988 to 2008) on plant assemblages, grazing potential, and diversity of palatable species in southern Karoo rangelands, South Africa. 3.,We used herbivore exclusion experiments to test whether resting rangeland for 20 years enables recovery of plant assemblages (where seed sources are present within 50 m), regardless of previous grazing history. Mean annual rainfall over this period was 15% higher than the mean annual rainfall for the preceding 80 years and included two exceptionally wet years. 4.,While rainfall was a primary driver of total vegetation cover, grazing history explained differences in plant species composition: plots with shared historical grazing intensity were more similar than plots with the same grazing regimes between 1988 and 2008. 5.,In historically heavily-grazed exclusion plots, cover of the palatable species Tripteris sinuata (formerly Osteospermum sinuatum) returned to levels comparable to that in both exclusion and lightly-grazed plots with a moderate grazing history. Five palatable species (Pteronia empetrifolia, Tetragonia spicata, Berkheya spinosa, Hereroa latipetala and Ruschia spinosa) failed to re-establish, however, despite the presence of seed-producing plants nearby. Furthermore, only cover of P. empetrifolia increased significantly in historically moderately-grazed plots. Cover of unpalatable plants (e.g. Pteronia pallens) increased in all plots over time. 6.Synthesis and applications. These findings suggest that present species composition of arid shrublands reflects historical management at time scales greater than 20 years. Despite high rainfall enabling the return of grazing potential through recovery of a single forage species, rest alone did not ensure the return of all palatable species, with implications for rangeland resilience. Restoring the full suite of palatable species over management timeframes will require more complex interventions such as reseeding or selective clearing. [source] New approaches to understanding late Quaternary climate fluctuations and refugial dynamics in Australian wet tropical rain forestsJOURNAL OF BIOGEOGRAPHY, Issue 2 2009Jeremy VanDerWal Abstract Aim, We created spatially explicit models of palaeovegetation stability for the rain forests of the Australia Wet Tropics. We accounted for the climatic fluctuations of the late Quaternary, improving upon previous palaeovegetation modelling for the region in terms of data, approach and coverage of predictions. Location, Australian Wet Tropics. Methods, We generated climate-based distribution models for broad rain forest vegetation types using contemporary and reconstructed ,pre-clearing' vegetation data. Models were projected onto previously published palaeoclimate scenarios dating to c. 18 kyr bp. Vegetation stability was estimated as the average likelihood that a location was suitable for rain forest through all climate scenarios. Uncertainty associated with model projections onto novel environmental conditions was also tracked. Results, Upland rain forest was found to be the most stable of the wet forest vegetation types examined. We provide evidence that the lowland rain forests were largely extirpated from the region during the last glacial maximum, with only small, marginally suitable fragments persisting in two areas. Models generated using contemporary vegetation data underestimated the area of environmental space suitable for rain forest in historical time periods. Model uncertainty resulting from projection onto novel environmental conditions was low, but generally increased with the number of years before present being modelled. Main conclusions, Climate fluctuations of the late Quaternary probably resulted in dramatic change in the extent of rain forest in the region. Pockets of high-stability upland rain forest were identified, but extreme bottlenecks of area were predicted for lowland rain forest. These factors are expected to have had a dramatic impact on the historical dynamics of population connectivity and patterns of extinction and recolonization of dependent fauna. Finally, we found that models trained on contemporary vegetation data can be problematic for reconstructing vegetation patterns under novel environmental conditions. Climatic tolerances and the historical extent of vegetation may be underestimated when artificial vegetation boundaries imposed by land clearing are not taken into account. [source] Anthropogenic disturbance and the formation of oak savanna in central Kentucky, USAJOURNAL OF BIOGEOGRAPHY, Issue 5 2008Ryan W. McEwan Abstract Aim, To deepen understanding of the factors that influenced the formation of oak savanna in central Kentucky, USA. Particular attention was focused on the link between historical disturbance and the formation of savanna ecosystem structure. Location, Central Kentucky, USA. Methods, We used dendrochronological analysis of tree-ring samples to understand the historical growth environment of remnant savanna stems. We used release detection and branch-establishment dates to evaluate changes in tree growth and the establishment of savanna physiognomy. We contrasted our growth chronology with reference chronologies for regional tree growth, climate and human population dynamics. Results, Trees growing in Kentucky Inner Bluegrass Region (IBR) savanna remnants exhibited a period of suppression, extending from the establishment date of the tree to release events that occurred c. 1800. This release resulted in a tripling of the annual radial growth rate from levels typical of oaks suppressed under a forest canopy (< 1 mm year,1) to levels typical of open-grown stems (3 mm year,1). The growth releases in savanna trees coincided with low branch establishment. Over the release period, climatic conditions remained relatively constant and growth in regional forest trees was even; however, the growth increase in savanna stems was strongly correlated with a marked increase in Euro-American population density in the region. Main conclusions, Our data suggest that trees growing in savanna remnants originated in the understorey of a closed canopy forest. We hypothesize that Euro-American land clearing to create pasturelands released these trees from light competition and resulted in the savanna physiognomy that is apparent in remnant stands in the IBR. Although our data suggest that savanna trees originated in a forest understorey, this system structure itself may have been a result of an unprecedented lack of Native American activity in the region due to population loss associated with pandemics brought to North America by Euro-Americans. We present a hypothetical model that links human population dynamics, land-use activities and ecosystem structure. Our model focuses on the following three land-use eras: Native American habitation/utilization; land abandonment; and Euro-American land clearance. Ecological understanding of historical dynamics in other ecosystems of eastern North America may be enhanced through recognition of these eras. [source] Leichhardt's maps: 100 years of change in vegetation structure in inland QueenslandJOURNAL OF BIOGEOGRAPHY, Issue 1 2008R. J. Fensham Abstract Aim, To address the hypothesis that there has been a substantial increase in woody vegetation cover (,vegetation thickening') during the 100 years after the burning practices of aboriginal hunter-gatherers were abruptly replaced by the management activities associated with pastoralism in north-east Australia. Location, Three hundred and eighty-three sites on 3000 km transect, inland Queensland, Australia. Methods, Vegetation structure descriptions from the route notes of the first European exploration of the location by Ludwig Leichhardt in 1844,45 were georeferenced and compiled. Leichhardt's application of structural descriptors (e.g. ,scrub', ,open forest', ,plain') was interpreted as domains within a matrix of tall stratum and low stratum woody cover. Woody cover was also interpreted for the same locations using aerial photography that largely pre-dates extensive land clearing (1940s,1970s) and compared with their structural domain in 1844,45. The fire-sensitive tree, cypress-pine (Callitris glaucophylla) was singled out for case study because it has been widely proposed that the density of this tree has substantially increased under European pastoral management. Results, The coarse resolution of this analysis indicates that the structure of the vegetation has been stable over the first 100 years of pastoralism. For example treeless or sparsely treed plains described by Leichhardt (1844,45) had the same character on the aerial photography (1945,78). Leichhardt typically described vegetation that includes cypress-pine as having a ,thicket' structure suggesting dense regenerating stands of small trees, consistent with the signature typical on the aerial photography. Main conclusions, A large data set of geographically located descriptions of vegetation structure from the first European traverse of inland Australia compared with vegetation structure determined from aerial photography does not support the hypothesis that vegetation thickening has been extensive and substantial. On the contrary the study suggests that the structure of the vegetation has been relatively stable for the first 100 years of European settlement and pastoralism except for those areas that have been affected by broad-scale clearing. [source] Auditor,Provided Consultancy Services and their Associations with Audit Fees and Audit OpinionsJOURNAL OF BUSINESS FINANCE & ACCOUNTING, Issue 5-6 2002Michael Firth This study examines the relationships between non,audit services fees (consultancy fees) paid to auditors and (1) audit fees, and (2) the occurrence of qualified audit opinions. The positive association between consultancy fees and audit fees is shown to be due to certain company specific events that generate a demand for consultancy services as well as requiring additional audit effort. Identified company specific events are mergers and acquisitions, new share issues, new accounting and information systems, new CEOs, and corporate restructurings. When these events are absent, there is no statistically significant relationship between audit fees and consultancy fees after controlling for company size. Companies that have relatively high consultancy fees are more likely to receive a clean audit opinion. This may be due to the non,audit work clearing up problem areas at the client company or it may be due to high consultancy fees impairing auditor independence. With the available data it is not possible to distinguish between these two reasons. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||