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1.
Philos Trans A Math Phys Eng Sci ; 379(2210): 20210104, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34565218

RESUMO

Mitigating climate change requires a diverse portfolio of technologies and approaches, including negative emissions or removal of greenhouse gases. Previous literature focuses primarily on carbon dioxide removal, but methane removal may be an important complement to future efforts. Methane removal has at least two key benefits: reducing temperature more rapidly than carbon dioxide removal and improving air quality by reducing surface ozone concentration. While some removal technologies are being developed, modelling of their impacts is limited. Here, we conduct the first simulations using a methane emissions-driven Earth System Model to quantify the climate and air quality co-benefits of methane removal, including different rates and timings of removal. We define a novel metric, the effective cumulative removal, and use it to show that each effective petagram of methane removed causes a mean global surface temperature reduction of 0.21 ± 0.04°C and a mean global surface ozone reduction of 1.0 ± 0.2 parts per billion. Our results demonstrate the effectiveness of methane removal in delaying warming thresholds and reducing peak temperatures, and also allow for direct comparisons between the impacts of methane and carbon dioxide removal that could guide future research and climate policy. This article is part of a discussion meeting issue 'Rising methane: is warming feeding warming? (part 1)'.

2.
Nature ; 591(7851): 599-603, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33762765

RESUMO

Terrestrial ecosystems remove about 30 per cent of the carbon dioxide (CO2) emitted by human activities each year1, yet the persistence of this carbon sink depends partly on how plant biomass and soil organic carbon (SOC) stocks respond to future increases in atmospheric CO2 (refs. 2,3). Although plant biomass often increases in elevated CO2 (eCO2) experiments4-6, SOC has been observed to increase, remain unchanged or even decline7. The mechanisms that drive this variation across experiments remain poorly understood, creating uncertainty in climate projections8,9. Here we synthesized data from 108 eCO2 experiments and found that the effect of eCO2 on SOC stocks is best explained by a negative relationship with plant biomass: when plant biomass is strongly stimulated by eCO2, SOC storage declines; conversely, when biomass is weakly stimulated, SOC storage increases. This trade-off appears to be related to plant nutrient acquisition, in which plants increase their biomass by mining the soil for nutrients, which decreases SOC storage. We found that, overall, SOC stocks increase with eCO2 in grasslands (8 ± 2 per cent) but not in forests (0 ± 2 per cent), even though plant biomass in grasslands increase less (9 ± 3 per cent) than in forests (23 ± 2 per cent). Ecosystem models do not reproduce this trade-off, which implies that projections of SOC may need to be revised.


Assuntos
Dióxido de Carbono/metabolismo , Sequestro de Carbono , Plantas/metabolismo , Solo/química , Biomassa , Pradaria , Modelos Biológicos
3.
Aust Vet J ; 99(1-2): 44-45, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33063317

RESUMO

In 2012 when many sheep flocks in northern-central Tasmania were experiencing a high prevalence of ovine Johne's disease, 34 wild adult fallow deer shot on or near infected properties were negative to microscopic Mptb lesions of the ileo-caecal valve, terminal ileum and ileo-caecal lymph nodes. This study demonstrated 95% confidence of detecting Johne's disease in this fallow deer population if ≥10% of animals were shedding Mycobacterium avium subsp. paratuberculosis in their faeces, or if ≥21% of animals were sub-clinically infected.


Assuntos
Cervos , Mycobacterium avium subsp. paratuberculosis , Paratuberculose , Doenças dos Ovinos , Animais , Paratuberculose/epidemiologia , Ovinos , Tasmânia/epidemiologia
4.
Environ Sci Technol ; 50(6): 3275-82, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26866674

RESUMO

Oil and natural gas development in the Bakken shale play of North Dakota has grown substantially since 2008. This study provides a comprehensive overview and analysis of water quantity and management impacts from this development by (1) estimating water demand for hydraulic fracturing in the Bakken from 2008 to 2012; (2) compiling volume estimates for maintenance water, or brine dilution water; (3) calculating water intensities normalized by the amount of oil produced, or estimated ultimate recovery (EUR); (4) estimating domestic water demand associated with the large oil services population; (5) analyzing the change in wastewater volumes from 2005 to 2012; and (6) examining existing water sources used to meet demand. Water use for hydraulic fracturing in the North Dakota Bakken grew 5-fold from 770 million gallons in 2008 to 4.3 billion gallons in 2012. First-year wastewater volumes grew in parallel, from an annual average of 1,135,000 gallons per well in 2008 to 2,905,000 gallons in 2012, exceeding the mean volume of water used in hydraulic fracturing and surpassing typical 4-year wastewater totals for the Barnett, Denver, and Marcellus basins. Surprisingly, domestic water demand from the temporary oilfield services population in the region may be comparable to the regional water demand from hydraulic fracturing activities. Existing groundwater resources are inadequate to meet the demand for hydraulic fracturing, but there appear to be adequate surface water resources, provided that access is available.


Assuntos
Fraturamento Hidráulico/métodos , Recursos Hídricos , Água Subterrânea , Fraturamento Hidráulico/estatística & dados numéricos , Gás Natural , North Dakota , Campos de Petróleo e Gás , Águas Residuárias/estatística & dados numéricos , Poluentes Químicos da Água/análise
5.
Aust Vet J ; 93(11): 387-93, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26503532

RESUMO

BACKGROUND: Avian influenza viruses (AIVs) are found worldwide in numerous bird species, causing significant disease in gallinaceous poultry and occasionally other species. Surveillance of wild bird reservoirs provides an opportunity to add to the understanding of the epidemiology of AIVs. METHODS: This study examined key findings from the National Avian Influenza Wild Bird Surveillance Program over a 5-year period (July 2007-June 2012), the main source of information on AIVs circulating in Australia. RESULTS: The overall proportion of birds that tested positive for influenza A via PCR was 1.9 ± 0.1%, with evidence of widespread exposure of Australian wild birds to most low pathogenic avian influenza (LPAI) subtypes (H1-13, H16). LPAI H5 subtypes were found to be dominant and widespread during this 5-year period. CONCLUSION: Given Australia's isolation, both geographically and ecologically, it is important for Australia not to assume that the epidemiology of AIV from other geographic regions applies here. Despite all previous highly pathogenic avian influenza outbreaks in Australian poultry being attributed to H7 subtypes, widespread detection of H5 subtypes in wild birds may represent an ongoing risk to the Australian poultry industry.


Assuntos
Influenza Aviária/epidemiologia , Influenza Aviária/virologia , Animais , Animais Selvagens/sangue , Animais Selvagens/virologia , Anticorpos Antivirais , Austrália/epidemiologia , Aves , Fezes/virologia , Geografia , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/sangue , Modelos Lineares , Orofaringe/virologia , Reação em Cadeia da Polimerase , Vigilância da População
6.
Environ Sci Technol ; 48(21): 12552-60, 2014 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-25327769

RESUMO

Identifying the geochemical fingerprints of fluids that return to the surface after high volume hydraulic fracturing of unconventional oil and gas reservoirs has important applications for assessing hydrocarbon resource recovery, environmental impacts, and wastewater treatment and disposal. Here, we report for the first time, novel diagnostic elemental and isotopic signatures (B/Cl, Li/Cl, δ11B, and δ7Li) useful for characterizing hydraulic fracturing flowback fluids (HFFF) and distinguishing sources of HFFF in the environment. Data from 39 HFFFs and produced water samples show that B/Cl (>0.001), Li/Cl (>0.002), δ11B (25-31‰) and δ7Li (6-10‰) compositions of HFFF from the Marcellus and Fayetteville black shale formations were distinct in most cases from produced waters sampled from conventional oil and gas wells. We posit that boron isotope geochemistry can be used to quantify small fractions (∼0.1%) of HFFF in contaminated fresh water and likely be applied universally to trace HFFF in other basins. The novel environmental application of this diagnostic isotopic tool is validated by examining the composition of effluent discharge from an oil and gas brine treatment facility in Pennsylvania and an accidental spill site in West Virginia. We hypothesize that the boron and lithium are mobilized from exchangeable sites on clay minerals in the shale formations during the hydraulic fracturing process, resulting in the relative enrichment of boron and lithium in HFFF.


Assuntos
Água Doce/química , Campos de Petróleo e Gás , Águas Residuárias/química , Poluentes Químicos da Água/química , Resíduos Industriais , Pennsylvania , West Virginia
7.
Ecol Appl ; 21(3): 678-94, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21639036

RESUMO

In arid regions throughout the world, shallow phreatic aquifers feed natural oases of much higher productivity than would be expected solely from local rainfall. In South America, the presence of well-developed Prosopis flexuosa woodlands in the Monte Desert region east of the Andes has puzzled scientists for decades. Today these woodlands provide crucial subsistence to local populations, including descendants of the indigenous Huarpes. We explore the vulnerability and importance of phreatic groundwater for the productivity of the region, comparing the contributions of local rainfall to that of remote mountain recharge that is increasingly being diverted for irrigated agriculture before it reaches the desert. We combined deep soil coring, plant measurements, direct water-table observations, and stable-isotopic analyses (2H and 18O) of meteoric, surface, and ground waters at three study sites across the region, comparing woodland stands, bare dunes, and surrounding shrublands. The isotopic composition of phreatic groundwaters (delta2H: -137 per thousand +/- 5 per thousand) closely matched the signature of water brought to the region by the Mendoza River (-137 per thousand +/- 6 per thousand), suggestin that mountain-river infiltration rather than in situ rainfall deep drainage (-39 per thousand +/- 19 per thousand) was the dominant mechanism of recharge. Similarly, chloride mass balances determined from deep soil profiles (> 6 m) suggested very low recharge rates. Vegetation in woodland ecosystems, where significant groundwater discharge losses, likely >100 mm/yr occurred, relied on regionally derived groundwater located from 6.5 to 9.5 m underground. At these locations, daily water-table fluctuations of 10 mm, and stable-isotopic measurements of plant water, indicated groundwater uptake rates of 200-300 mm/yr. Regional scaling suggests that groundwater evapotranspiration reaches 18-42 mm/yr across the landscape, accounting for 7 17% of the Mendoza River flow regionally. Our study highlights the reliance of ecosystem productivity in natural oases on Andean snowmelt, which is increasingly being diverted to one of the largest irrigated regions of the continent. Understanding the ecohydrological coupling of mountain and desert ecosystems here and elsewhere should help managers balance production agriculture and conservation of unique woodland ecosystems and the rural communities that rely on them.


Assuntos
Clima Desértico , Ecossistema , Movimentos da Água , Água , Argentina , Monitoramento Ambiental , Sedimentos Geológicos , Solo/química , Fatores de Tempo
8.
J Anim Sci ; 88(2): 581-93, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19897628

RESUMO

This paper reports an investigation into metabolic and endocrine maturity in the neonate lamb and the relationships between litter size, birth weight, and maternal metabolic and endocrine variables on behavior at birth and survival over the first 72 h of life. Data were from multiparous, fine-wool Merino ewes (n = 150; equal numbers of single-lamb and twin-lamb bearing status) lambed on pasture after late gestational glucocorticoid treatments. Stepwise multiple regression analysis was used to investigate relationships between lamb survival, behavior, endocrinology, and physiology. Improved lamb viability at 72 h after birth was related to decreased chill indices at birth, singleton litter status, greater presuckling rectal temperature, increased ewe prelambing plasma ghrelin concentration, female sex, heavier birth weight, and decreased lamb presuckling plasma glucose concentration. Greater rectal temperatures were associated with heavier birth weight and gestation lengths shorter than 146 d, but no relationship with neonatal behavioral progression was evident. Presuckling glucose concentrations were greater in singletons and lambs born to ewes of greater BCS at d 95 of gestation, and lambs of heavier birth weight, but were also associated with decreased rectal temperatures. This might reflect a delay in glucose utilization during the adjustment from a fetal metabolic rate to a rate appropriate for cold external environments. Singleton lambs exhibited decreased presuckling plasma NEFA concentrations and were almost 8 times more likely to survive to 72 h than a twin-born lamb. Birth weight was lesser in lambs born to ewes with elevated plasma glucose and leptin concentrations before lambing and was positively related to ewe BW at d 95 of gestation and to length of gestation. Greater presuckling plasma ghrelin and leptin concentrations were measured for shorter gestation lengths. Neonate presuckling ghrelin concentrations above 650 pg/mL tended (P = 0.077) to be associated with improved lamb survival to 72 h. This was consistent with a curvilinear decline in neonate survival rates to 72 h after birth as time of latency to suckle increased. No relationship was observed between lamb plasma glucose concentrations and behavioral expression after lambing. Lambs exhibiting greater metabolic and endocrine maturity at birth had improved survival in a cold environment to 72 h after birth. The role of ghrelin in ovine fetal development warrants further investigation.


Assuntos
Animais Recém-Nascidos/fisiologia , Peso ao Nascer/fisiologia , Tamanho da Ninhada de Vivíparos/fisiologia , Ovinos/fisiologia , Criação de Animais Domésticos , Animais , Animais Recém-Nascidos/metabolismo , Animais Lactentes/fisiologia , Metabolismo Basal/fisiologia , Comportamento Animal/fisiologia , Glicemia/análise , Glicemia/fisiologia , Temperatura Corporal/fisiologia , Feminino , Grelina/sangue , Leptina/sangue , Masculino , Estado Nutricional/fisiologia , Fatores Sexuais , Ovinos/metabolismo , Ureia/sangue
9.
J Anim Sci ; 87(10): 3167-78, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19542513

RESUMO

Perinatal mortality is a major contributing factor to reproductive wastage in grazing sheep industries. Enhanced metabolic and endocrine maturity at birth may improve the behavioral competency and thermoregulatory ability of neonates, potentially improving lamb survival over the first 72 h of life. Maternal glucocorticoid treatment in late gestation was investigated as a mechanism for manipulating metabolic and endocrine maturity in the ovine neonate. Multiparous, fine-wool Merino ewes (n = 150) were divided into 3 groups to lamb on pasture. Within each group, 5 single-lamb and 5 twin-lamb bearing ewes were randomly allocated to 1 of 5 treatments. Treatments included a saline control (1 mL), or dexamethasone (2 mg/mL as the sodium phosphate) injected intramuscularly at 1 of 2 dose rates (1.5 or 3.0 mg) at d 130 or 141 of gestation. One-half of the control ewes were injected at d 130 and the remainder at d 141. Dexamethasone treatment had no effect on lamb survival to 72 h after birth, although there tended (P = 0.09) to be a smaller proportion of lambs dying due to dystocia than for control lambs. Heart girth at birth in singleton and twin lambs was reduced (P < 0.01) at the greater dose rate. Further, treatment also reduced birth weight (by about 5%) and presuckling rectal temperatures in twin lambs, but not in singleton lambs. These reductions were also dependent on the sex of the lamb. Dexamethasone treatment did not alter gestation length or lamb presuckling plasma glucose, NEFA, urea, or leptin concentrations, but treatment at d 141 increased (P < 0.05) ghrelin concentrations in singleton and male lambs. Behavioral interactions between ewes and neonatal lambs were generally unaffected, although treatment at d 130 produced lambs that took longer to bleat than lambs of untreated ewes (P < 0.05). Treatment did not affect the concentration of measured blood metabolites or hormones at weaning. Although there were interactions between litter size, lamb sex, and the dose rate and time of treatment on weaning weight, BW recorded 73 d after weaning was unaffected by treatment. Despite changes in birth weight, rectal temperature, lamb behavior, and presuckling plasma ghrelin concentrations, survival in the first 72 h of life, and lamb growth performance were unaffected by periparturient maternal glucocorticoid treatment.


Assuntos
Animais Recém-Nascidos/metabolismo , Dexametasona/farmacologia , Glucocorticoides/farmacologia , Ovinos/metabolismo , Animais , Comportamento Animal/fisiologia , Peso ao Nascer/fisiologia , Glicemia/análise , Temperatura Corporal/fisiologia , Dexametasona/administração & dosagem , Ácidos Graxos não Esterificados/sangue , Feminino , Grelina/sangue , Glucocorticoides/administração & dosagem , Leptina/sangue , Masculino , Gravidez , Distribuição Aleatória , Análise de Sobrevida , Ureia/sangue
10.
Oecologia ; 141(4): 620-8, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15322902

RESUMO

Explanations for the occurrence of deep-rooted plants in arid and semi-arid ecosystems have traditionally emphasized the uptake of relatively deep soil water. However, recent hydrologic data from arid systems show that soil water potentials at depth fluctuate little over long time periods, suggesting this water may be rarely utilized or replenished. In this study, we examine the distributions of root biomass, soil moisture and nutrient contents to 10-m depths at five semi-arid and arid sites across southwestern USA. We couple these depth distributions with strontium (Sr) isotope data that show deep (>1 m) nutrient uptake is prevalent at four of the five sites. At all of the sites, the highest abundance of one or more of the measured nutrients occurred deep within the soil profile, particularly for P, Ca2+ and Mg2+. Phosphate contents were greater at depth than in the top meter of soil at three of five sites. At Jornada, for example, the 2-3 m depth increment had twice the extractable P as the top meter of soil, despite the highest concentrations of P occurring at the surface. The prevalence of such deep resource pools, and our evidence for cation uptake from them, suggest nutrient uptake as a complementary explanation for the occurrence of deep-rooted plants in arid and semi-arid systems. We propose that hydraulic redistribution of shallow surface water to deep soil layers by roots may be the mechanism through which deep soil nutrients are mobilized and taken up by plants.


Assuntos
Ecossistema , Fenômenos Fisiológicos Vegetais , Raízes de Plantas/crescimento & desenvolvimento , Solo/análise , Biomassa , Cálcio/análise , Cálcio/farmacocinética , Água Doce , Umidade , Magnésio/análise , Magnésio/farmacocinética , Fósforo/análise , Fósforo/farmacocinética , Raízes de Plantas/metabolismo , Sudoeste dos Estados Unidos , Isótopos de Estrôncio
12.
Obstet Gynecol ; 96(6): 1003-8, 2000 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11084193

RESUMO

OBJECTIVE: To develop, implement, and evaluate an electronic record that tracks antepartum, intrapartum, and postpartum care. METHODS: The Standard Obstetric Record Charting system (STORC) was created by a group of programmers and clinicians who developed screen designs, reports, pick lists, and standard notes, and ensured a flexible, yet standard system. To evaluate data within the system, ORYX (Joint Commission) performance measures were collected retrospectively and compared with STORC data. RESULTS: The STORC, officially implemented as our complete inpatient and outpatient obstetric record in March 1998, provided seamless integration of antepartum, intrapartum, and postpartum care records, standard forms, and standard and ad hoc reports. Data for customizable case and procedure lists are generated easily. Unplanned and total cesarean deliveries were identified retrospectively in 0% (0 of 18) of charts reviewed for ORYX; however, STORC identified the actual rates of each as 8.3% (23 of 276) and 12.3% (34 of 276), respectively. Other critical ORYX measures not identified by retrospective data collection, but accurately provided by STORC, included rates of third and fourth degree lacerations, postpartum hemorrhage, low and extremely low birth weights, and macrosomia. CONCLUSION: After implementation in a large referral center, completeness and accuracy of charting and rapid access to obstetric outcome data were improved. Provider acceptance of the system also was dramatic and improved over time as a result of direct development oversight by obstetric health care providers, local control of system changes, and immediate access to outcome data. (Obstet Gynecol 2000;96:1003-8.)


Assuntos
Sistemas Computadorizados de Registros Médicos , Obstetrícia , Adulto , Peso ao Nascer , Cesárea/estatística & dados numéricos , Redes de Comunicação de Computadores , Feminino , Humanos , Recém-Nascido , Complicações do Trabalho de Parto/epidemiologia , Obstetrícia/estatística & dados numéricos , Gravidez , Resultado da Gravidez , Software
13.
Trends Plant Sci ; 5(11): 482-8, 2000 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11077257

RESUMO

Plant water loss, regulated by stomata and driven by atmospheric demand, cannot exceed the maximum steady-state supply through roots. Just as an electric circuit breaks when carrying excess current, the soil-plant continuum breaks if forced to transport water beyond its capacity. Exciting new molecular, biophysical and ecological research suggests that roots are the weakest link along this hydraulic flow path. We attempt here to predict rooting depth and water uptake using the hydraulic properties of plants and the soil, and also to suggest how new physiological tools might contribute to larger-scale studies of hydraulic lift, the water balance and biosphere-atmosphere interactions.


Assuntos
Raízes de Plantas/metabolismo , Água/metabolismo , Raízes de Plantas/fisiologia , Solo
14.
Mol Ecol ; 9(10): 1549-59, 2000 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11050550

RESUMO

As part of a large project to determine rooting depth and resource uptake on the Edwards Plateau of central Texas, we developed a DNA-based technique that allows the below-ground parts of all plants to be identified to the level of genus and usually to species. Identification is achieved by comparing DNA sequences of the internal transcribed spacer (ITS) region of the 18S-26S nuclear ribosomal DNA repeat, derived from below-ground plant material, with a reference ITS region database for plants at a site. The method works throughout plants because the plant ITS region can be PCR amplified using a set of universal primers. Congeneric species can usually be identified because the ITS region evolves relatively rapidly. In our study, all roots were easily identified to the level of genus; most congeneric species were identified solely by ITS sequence differences but some required a combination of ITS sequence data and above-ground surveys of species at a site. In addition to showing the feasibility and efficacy of our technique, we compare it with another DNA-based technique used to identify below-ground plant parts. Finally, we also describe a DNA extraction and purification technique that reliably provides high-quality DNA of sufficient quantity from roots so that PCR can be readily accomplished. Our technique should allow the below-ground parts of plants in any system to be identified and thereby open new possibilities for the study of below-ground plant communities.


Assuntos
DNA Espaçador Ribossômico , Raízes de Plantas/genética , Reação em Cadeia da Polimerase/métodos , Ribulose-Bifosfato Carboxilase , Sequência de Bases , Soluções Tampão , DNA de Plantas/isolamento & purificação , Bases de Dados Factuais , Dados de Sequência Molecular , Proteínas de Plantas/genética , Polimorfismo de Fragmento de Restrição , Especificidade da Espécie
15.
Science ; 287(5459): 1770-4, 2000 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-10710299

RESUMO

Scenarios of changes in biodiversity for the year 2100 can now be developed based on scenarios of changes in atmospheric carbon dioxide, climate, vegetation, and land use and the known sensitivity of biodiversity to these changes. This study identified a ranking of the importance of drivers of change, a ranking of the biomes with respect to expected changes, and the major sources of uncertainties. For terrestrial ecosystems, land-use change probably will have the largest effect, followed by climate change, nitrogen deposition, biotic exchange, and elevated carbon dioxide concentration. For freshwater ecosystems, biotic exchange is much more important. Mediterranean climate and grassland ecosystems likely will experience the greatest proportional change in biodiversity because of the substantial influence of all drivers of biodiversity change. Northern temperate ecosystems are estimated to experience the least biodiversity change because major land-use change has already occurred. Plausible changes in biodiversity in other biomes depend on interactions among the causes of biodiversity change. These interactions represent one of the largest uncertainties in projections of future biodiversity change.


Assuntos
Ecossistema , Agricultura , Animais , Atmosfera , Dióxido de Carbono , Clima , Água Doce , Modelos Biológicos , Nitrogênio
16.
Chiropr Hist ; 20(1): 21-32, 2000 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15049319

RESUMO

This is a limited chronology of some early legal cases wherein doctors of osteopathy and chiropractic were charged with practicing without a license prior to legalization of their respective professions. This is followed by appeals of their guilty verdicts to higher courts for what they hoped would be a favorable verdict. Not all medical-practice acts contained identical language to thwart empiricism in states, thus court verdicts became pivotal for future trials, to appeals, as case law examples of statue interpretation by the same or other states.


Assuntos
Quiroprática/história , Medicina Legal/história , Jurisprudência/história , Medicina Osteopática/história , História do Século XIX , História do Século XX , Estados Unidos
17.
Oecologia ; 123(3): 312-317, 2000 May.
Artigo em Inglês | MEDLINE | ID: mdl-28308585

RESUMO

The savannas (cerrado) of south-central Brazil are currently subjected to frequent anthropogenic burning, causing widespread reduction in tree density. Increasing concentrations of atmospheric CO2 could reduce the impact of such frequent burning by increasing the availability of nonstructural carbohydrate, which is necessary for resprouting. We tested the hypotheses that elevated CO2 stimulates resprouting and accelerates replenishment of carbohydrate reserves. Using a factorial experiment, seedlings of a common Brazilian savanna tree, Keilmeyera coriacea, were grown at 350 ppm and 700 ppm CO2 and at two nutrient levels. To simulate burning, the plants were either clipped at 15 weeks or were left unclipped. Among unclipped plants, CO2 and nutrients both stimulated growth, with no significant interaction between nutrient and CO2 effects. Among clipped plants, both CO2 and nutrients stimulated resprouting. However, there was a strong interaction between CO2 and nutrient effects, with CO2 having a significant effect only in the presence of high nutrient availability. Under elevated CO2, carbohydrate reserves remained at higher levels following clipping. Root total nonstructural carbohydrate remained above 36% in all treatments, so carbohydrate reserves did not limit regrowth. These results indicate that under elevated CO2 this species may be better able to endure the high frequency of anthropogenic burning in the Brazilian savannas.

18.
Proc Natl Acad Sci U S A ; 96(20): 11387-92, 1999 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-10500186

RESUMO

Belowground vertical community composition and maximum rooting depth of the Edwards Plateau of central Texas were determined by using DNA sequence variation to identify roots from caves 5-65 m deep. Roots from caves were identified by comparing their DNA sequences for the internal transcribed spacer (ITS) region of the 18S-26S ribosomal DNA repeat against a reference ITS database developed for woody plants of the region. Sequencing the ITS provides, to our knowledge, the first universal method for identifying plant roots. At least six tree species in the system grew roots deeper than 5 m, but only the evergreen oak, Quercus fusiformis, was found below 10 m. The maximum rooting depth for the ecosystem was approximately 25 m. (18)O isotopic signatures for stem water of Q. fusiformis confirmed water uptake from 18 m underground. The availability of resources at depth, coupled with small surface pools of water and nutrients, may explain the occurrence of deep roots in this and other systems.


Assuntos
DNA de Plantas/química , DNA Ribossômico/química , Ecossistema , Sequência de Bases , Dados de Sequência Molecular
19.
Chiropr Hist ; 19(1): 45-52, 1999 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11624039

RESUMO

The first few chiropractors in Massachusetts practiced as they desired, unmolested by the authorities. All this changed after Joe Shelby Riley, D.C., established his New England College of Chiropractic in Boston in 1911. Printed publicity got out as to the tuition costs, length of the course and what graduates could expect to earn in a short time, when the police stepped in. They arrested first J.O. Zimmerman, D.C., of Boston, followed by Dr. Riley, a school president, then Samuel Mendelson, D.C., in Lynn, all for illegal practices. From the judical decision in Commonwealth v Zimmerman, 1915 by the Supreme Judicial Court (State Supreme Court), the high court held that the practice of chiropractic to be the illegal practice of medicine without a license, according to the Commonwealth laws of 1902. Next came the Commonwealth v New England College of Chiropractic; this case was shortly followed on appeal from the Municipal Court in Boston, to the Suffolk County Superior Court, to the Supreme Judicial Court like Zimmerman. In this case against Dr. Riley and his school, the high court affirmed the school to be illegal because Dr. Riley had failed to receive authority from the Great General Court (the Legislature) to get a bill passed authorizing the school to have the right of granting degrees. According to the Boston Herald, all this legal action was the culmination of a campaign spearheaded by the Massachusetts Medical Society.


Assuntos
Quiroprática/história , Jurisprudência/história , Legislação Médica/história , Licenciamento em Medicina/história , Faculdades de Medicina/história , História do Século XX , Estados Unidos
20.
Chiropr Hist ; 19(2): 49-54, 1999 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11624126

RESUMO

This is a chronology of events, of bills introduced, those that died in committee or were vetoed by the Governor before enactment of California's Radiation Control Act, first in the nation and enacted in 1969. Seeing confidential documents from Committee and Governor's Office for the first time adds color to the article. This article also memorializes Senator Walter W. Stiern and Mr. Gordon H. Garland who carried the chiropractic torch to make our inclusion into this act a reality.


Assuntos
Quiroprática/história , Legislação Médica/história , Proteção Radiológica/história , Governo Estadual , História do Século XX , Estados Unidos
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