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1.
Res Sq ; 2024 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-38978585

RESUMEN

Resistance to endocrine therapies remains a major clinical hurdle in breast cancer. Mutations to estrogen receptor alpha (ERα) arise after continued therapeutic pressure. Next generation selective estrogen receptor modulators and degraders/downregulators (SERMs and SERDs) show clinical efficacy, but responses are often non-durable. A tyrosine to serine point mutation at position 537 in the ERα ligand binding domain (LBD) is among the most common and most pathogenic alteration in this setting. It enables endocrine therapy resistance by superceding intrinsic structural-energetic gatekeepers of ER hormone-dependence, it enhances metastatic burden by enabling neomorphic ER-dependent transcriptional programs, and it resists SERM and SERD inhibiton by reducing their binding affinities and abilities to antagonize transcriptional coregulator binding. However, a subset of SERMs and SERDs can achieve efficacy by adopting poses that force the mutation to engage in a new interaction that favors the therapeutic receptor antagonist conformation. We previously described a chemically unconventional SERM, T6I-29, that demonstrates significant anti-proliferative activities in Y537S ERα breast cancer cells. Here, we use a comprehensive suite of structural-biochemical, in vitro, and in vivo approaches to better T6I-29's activities in breast cancer cells harboring Y537S ERα. RNA sequencing in cells treated with T6I-29 reveals a neomorphic downregulation of DKK1, a secreted glycoprotein known to play oncogenic roles in other cancers. Importantly, we find that DKK1 is significantly enriched in ER+ breast cancer plasma compared to healthy controls. This study shows how new SERMs and SERDs can identify new therapeutic pathways in endocrine-resistant ER+ breast cancers.

2.
bioRxiv ; 2024 Jun 02.
Artículo en Inglés | MEDLINE | ID: mdl-38854123

RESUMEN

Resistance to endocrine therapies remains a major clinical hurdle in breast cancer. Mutations to estrogen receptor alpha (ERα) arise after continued therapeutic pressure. Next generation selective estrogen receptor modulators and degraders/downregulators (SERMs and SERDs) show clinical efficacy, but responses are often non-durable. A tyrosine to serine point mutation at position 537 in the ERα ligand binding domain (LBD) is among the most common and most pathogenic alteration in this setting. It enables endocrine therapy resistance by superceding intrinsic structural-energetic gatekeepers of ER hormone-dependence, it enhances metastatic burden by enabling neomorphic ER-dependent transcriptional programs, and it resists SERM and SERD inhibiton by reducing their binding affinities and abilities to antagonize transcriptional coregulator binding. However, a subset of SERMs and SERDs can achieve efficacy by adopting poses that force the mutation to engage in a new interaction that favors the therapeutic receptor antagonist conformation. We previously described a chemically unconventional SERM, T6I-29, that demonstrates significant anti-proliferative activities in Y537S ERα breast cancer cells. Here, we use a comprehensive suite of structural-biochemical, in vitro, and in vivo approaches to better T6I-29's activities in breast cancer cells harboring Y537S ERα. RNA sequencing in cells treated with T6I-29 reveals a neomorphic downregulation of DKK1, a secreted glycoprotein known to play oncogenic roles in other cancers. Importantly, we find that DKK1 is significantly enriched in ER+ breast cancer plasma compared to healthy controls. This study shows how new SERMs and SERDs can identify new therapeutic pathways in endocrine-resistant ER+ breast cancers.

3.
NPJ Breast Cancer ; 8(1): 130, 2022 Dec 14.
Artículo en Inglés | MEDLINE | ID: mdl-36517522

RESUMEN

Estrogen receptor alpha (ERα) is a ligand-dependent master transcriptional regulator and key driver of breast cancer pathology. Small molecule hormones and competitive antagonists favor unique ERα conformational ensembles that elicit ligand-specific transcriptional programs in breast cancer and other hormone-responsive tissues. By affecting disparate ligand binding domain structural features, unconventional ligand scaffolds can redirect ERα genomic binding patterns to engage novel therapeutic transcriptional programs. To improve our understanding of these ERα structure-transcriptional relationships, we develop a series of chemically unconventional antagonists based on the antiestrogens elacestrant and lasofoxifene. High-resolution x-ray co-crystal structures show that these molecules affect both classical and unique structural motifs within the ERα ligand binding pocket. They show moderately reduced antagonistic potencies on ERα genomic activities but are effective anti-proliferative agents in luminal breast cancer cells. Interestingly, they favor a 4-hydroxytamoxifen-like accumulation of ERα in breast cancer cells but lack uterotrophic activities in an endometrial cell line. Importantly, RNA sequencing shows that the lead molecules engage transcriptional pathways similar to the selective estrogen receptor degrader fulvestrant. This advance shows that fulvestrant-like genomic activities can be achieved without affecting ERα accumulation in breast cancer cells.

4.
Sci Total Environ ; 849: 157692, 2022 Nov 25.
Artículo en Inglés | MEDLINE | ID: mdl-35908711

RESUMEN

Tailings is a generic term for waste material from the extraction and processing of minerals and frequently contain mineral and chemical residues. They are usually highly erodible and transportable via fluvial processes. Tailings are commonly stored in 'tailings dams' and such dams are a feature of many mine sites. As they impound water and sediment, tailings dams can be at risk from both catastrophic and gradual failure, especially if unmanaged. A fundamental question for their management is, can tailings dams ever be walk-away structures? Catastrophic failure occurs when there is a large scale rapid structural failure of the dam wall suddenly releasing large volumes of water and sediment. However, over time, there will the increased risk of gradual failure by the slow infilling of the dam and the erosion of the dam wall. Failure can occur where water overtops the dam wall and then incises through the wall due to a loss of freeboard in the dam, a situation which is more likely in legacy tailings dams where they have been filled, vegetated and abandoned. Here, firstly, a computer based landscape evolution model (CAESAR-Lisflood) is employed to assess a hypothetical tailings dam failure by erosion. Secondly, using an idealised example, it is demonstrated that given average climate conditions a dam can be sufficiently robust to last centuries. Thirdly, and longer term it is demonstrated that the tailings can be contained if (a) maintenance is conducted to increase the dam wall height over time or (b) a more robust dam wall is constructed to manage extreme events. However, erosion and infill will continue to reduce the integrity of any structure over time. Therefore, it is highly likely that tailings dams will require continued monitoring and maintenance. The method outlined provides a new tool for assessing any tailings facility for its erosional stability.


Asunto(s)
Ambiente , Minerales , Agua
5.
Sci Total Environ ; 817: 152690, 2022 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-34974006

RESUMEN

Soil organic carbon (SOC) is an important soil component. However, examining SOC at the large catchment scale is difficult due to the intensive labour requirements. This study examines SOC distribution at large (>500 km2) catchment scales using field-sampled SOC data and remote sensed vegetation indices located in eastern Australia (Krui River catchment - 562 km2; Merriwa River catchment - 808 km2) on grazing land-use basalt soil. The SOC data obtained was compared to digital elevation model (DEM) derived elevation and insolation data, as well as Normalised Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) values corresponding to each sample site. These indices were obtained from the MODIS sensor (Terra/Aqua) and Landsat series satellites. Vegetation Indices (VI) captured immediately prior to sampling demonstrated a poor correlation with SOC. The use of multiple, aggregated, prior VI data sets provided a good match with SOC. The strongest match occurred for Landsat 8 EVI, indicating that VIs with higher spatial and spectral resolution, which can account for atmospheric interference, have the potential to produce more accurate SOC mapping (Krui samples in 2006, R2 = 0.31, P < 0.01; Krui sampled in 2014, R2 = 0.41, P < 0.01; Merriwa samples in 2015, R2 = 0.37, P < 0.01). A sensitivity test for both remote sensing platforms demonstrated that the findings were robust. The results demonstrate that VIs are a reliable surrogate for historical vegetation growth in pasture dominated landscapes and therefore soil carbon inputs allowing for mapping of SOC across large catchment scales. Both Landsat and MODIS produced similar results and demonstrate that SOC can be reliably predicted at the large catchment scale and for different catchments in this environment with RMSE range of 0.79 to 1.06. The method and data can be applied globally and provides a new method for environmental assessment.


Asunto(s)
Carbono , Suelo , Australia , Carbono/análisis , Ríos
6.
Stem Cell Res ; 55: 102493, 2021 08.
Artículo en Inglés | MEDLINE | ID: mdl-34399163

RESUMEN

During embryo development, human primordial germ cells (hPGCs) express a naive gene expression program with similarities to pre-implantation naive epiblast (EPI) cells and naive human embryonic stem cells (hESCs). Previous studies have shown that TFAP2C is required for establishing naive gene expression in these cell types, however the role of additional naive transcription factors in hPGC biology is not known. Here, we show that unlike TFAP2C, the naive transcription factors KLF4 and TFCP2L1 are not required for induction of hPGC-like cells (hPGCLCs) from hESCs, and they have no role in establishing and maintaining a naive-like gene expression program in hPGCLCs with extended time in culture. Taken together, our results suggest a model whereby the molecular mechanisms that drive naive gene expression in hPGCs/hPGCLCs are distinct from those in the naive EPI/hESCs.


Asunto(s)
Células Germinativas , Células Madre Embrionarias Humanas , Diferenciación Celular , Células Germinativas/metabolismo , Células Madre Embrionarias Humanas/metabolismo , Humanos , Factor 4 Similar a Kruppel , Proteínas Represoras/metabolismo , Factores de Transcripción/genética , Transcriptoma
7.
Sci Total Environ ; 779: 146083, 2021 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-33735655

RESUMEN

Mine tailings are a by-product of the processing of minerals. At most mines they are a waste product that needs to be managed. Tailings composition and properties vary widely and are in most cases highly erodible due to their fine particle size and can contain elevated concentrations of unwanted minerals and process chemicals. Therefore, if released to the environment they can be a significant environmental problem. A common management strategy is to store them in 'tailings dams' where they will remain in perpetuity. Little work has been done to assess the long-term erosional behaviour of tailings dams. Computer based Landscape Evolution Models (LEMs) provide information on erosion rates, type of erosion and where erosion is likely to occur. They can therefore provide guidance on long-term behaviour which allows designs to be tested and improved. Here a LEM, SIBERIA, is used to assess two hypothetical tailings dam designs using different surface covers and climates. The results suggest that a tailings dam that can capture rainfall can erode less than a capped design that must shed any runoff. An embankment with a small and steep catchment has minimal erosion potential and any material eroded from the internal wall of the embankment is deposited internally and provides erosion protection. If the external embankment is maintained then there is potential for long-term encapsulation of tailings. The single biggest issue for the employment of LEMs is that of parameterisation and here assumes (1) a uniform and consistent armour or (2) a consistent and self-sustaining vegetation cover. The modelling and methods here provide a template for tailings dam assessment at other sites globally, and will improve tailings dam design and reduce environmental risk.

8.
J Breath Res ; 15(1): 016002, 2020 10 22.
Artículo en Inglés | MEDLINE | ID: mdl-33089830

RESUMEN

In the current pilot study we aimed to determine whether breath analysis could be used to help recognise intra-abdominal infection, using acute appendicitis as an exemplar condition. Our study included 53 patients (aged 18-88 years) divided into three groups: appendix group, 26 (13 male) patients suffering from acute appendicitis; control group 20 (seven male) patients undergoing elective abdominal surgery; normal group, seven patients who were clinically diagnosed with appendicitis, but whose appendix was normal on histological examination. Samples of breath were analysed using ion molecule reaction mass spectroscopy measuring the concentration of volatile compounds (VCs) with molecular masses 27-123. Intraperitoneal gas samples were collected from a subset of 23 patients (nine diagnosed with acute appendicitis). Statistically significant differences in the concentration of VCs in breath were found between the three groups. Acetone, isopropanol, propanol, butyric acid, and further unassigned VCs with molecular mass/charge ratio (m/z) 56, 61 and 87 were all identified with significant endogenous contributions. Principle component analysis was able to separate the control and appendicitis groups for seven variables: m/z = 56, 58, 59, 60, 61, 87 and 88. Comparing breath and intraperitoneal samples showed significant relationships for acetone and the VC with m/z = 61. Our data suggest that it may be possible to help diagnose acute appendicitis by breath analysis; however, factors such as length of starvation remain to be properly accounted for and the management or mitigation of background levels needs to be properly addressed, and larger studies relating breath VCs to the causative organisms may help to highlight the relative importance of individual VCs.


Asunto(s)
Apendicitis/diagnóstico , Pruebas Respiratorias/métodos , Infecciones Intraabdominales/diagnóstico , Acetona/análisis , Enfermedad Aguda , Adulto , Apendicitis/cirugía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Peritoneo/metabolismo , Proyectos Piloto , Análisis de Componente Principal , Manejo de Especímenes , Compuestos Orgánicos Volátiles/análisis
9.
Sci Total Environ ; 705: 135844, 2020 Feb 25.
Artículo en Inglés | MEDLINE | ID: mdl-31864168

RESUMEN

Soil organic carbon (SOC) is an essential component of the soil-landscape system. It is well recognised that SOC can reduce under some agricultural management practices. In recent years a concerted effort has been undertaken to increase SOC by employing different landscape management practices. Here we compare SOC in a grazing environment to that of an area where cattle have been excluded for over ten years using both a hillslope and whole of soil profile sampling strategy. Surface SOC concentrations (determined by cores) were significantly higher inside the exclusion area when compared to that outside demonstrating a rapid increase in SOC. Whole soil profile (to bedrock) assessment found that SOC decreased with depth both inside and outside of the shelterbelt. While SOC decreased with depth, there were significantly higher surface concentrations inside the exclusion area compared to outside. At depths >20 cm, SOC became increasingly homogenous for both datasets with little difference observed. The results suggest that the influence of the exclusion area on SOC accumulation at the site was only within the top 10-20 cm of the soil profile. The results highlight the importance of soil depth in quantifying SOC within the soil profile and SOC sequestration potential for sites at depth.

10.
Acta Psychol (Amst) ; 198: 102836, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-31279183

RESUMEN

An altered sense of the experience of time represents one of the nine dimensions that is conceived as characterizing a state of flow. While a number of other factors necessarily contribute to this overall experience of flow, subjective time perception is of particular quantitative interest and thus serves as the focus of the present meta-analysis. The extant body of relevant quantitative research was evaluated to identify data relating to both flow and change in the sense of time. Sixty-three (n = 63) articles were determined to qualify under the current specified inclusion criteria. These sixty-three studies yielded one thousand and ninety-four (n = 1094) effect sizes. All studies included in the meta-analysis were also coded for relevant moderator variables. Results indicated moderately positive correlations between affective, consciousness, and performance based aspects of flow (r = 0.4, 0.21, 0.17 respectively), thus reinforcing the original conceptualization of their relationship for the generation and maintenance of the flow state. Additionally, variations in environmental conditions (both physical and social) were found to have differential effects on the overall level of experienced flow. The results of this meta-analysis also serve to inform the process of further model development that can more accurately quantify and predict temporal perception as one metric of flow.


Asunto(s)
Percepción del Tiempo , Afecto , Estado de Conciencia , Humanos , Pensamiento
11.
Sci Total Environ ; 666: 618-630, 2019 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-30807952

RESUMEN

There is considerable debate over how different agricultural management systems such as minimum tillage and grazing affect soil organic carbon (SOC), soil nitrogen (SN) concentrations and soil erosion over the long-term. In this study SOC, SN and erosion characteristics were compared over a ten year period for two neighbouring sites with longstanding but different land management strategies; one cropped under a minimum tillage (MT) regime and one used for grazing on largely native pasture. Both sites (Hunter Valley, New South Wales, Australia) shared the same soil type (Euchrozem) and climate. SOC and SN were both found to be ~50% higher at the grazing site while erosion was found to be significantly greater (an order of magnitude) at the cropping site despite the application of MT practices. No discernible link between erosion and either SOC, SN or C:N was evident. While both sites have temporally constant SOC, SN and C:N, the MT site offers scope for increased SOC sequestration.

12.
J Breath Res ; 12(3): 036015, 2018 05 14.
Artículo en Inglés | MEDLINE | ID: mdl-29643267

RESUMEN

Breath acetone concentrations were measured in 141 subjects (aged 19-91 years, mean = 59.11 years, standard deviation = 12.99 years), male and female, undergoing an oral glucose tolerance test (OGTT), having been referred to clinic on suspicion of type 2 diabetes. Breath samples were measured using an ion-molecule-reaction mass spectrometer, at the commencement of the OGTT, and after 1 and 2 h. Subjects were asked to observe the normal routine before and during the OGTT, which includes an overnight fast and ingestion of 75 g glucose at the beginning of the routine. Several groups of diagnosis were identified: type 2 diabetes mellitus positive (T2DM), n = 22; impaired glucose intolerance (IGT), n = 33; impaired fasting glucose, n = 14; and reactive hypoglycaemia, n = 5. The subjects with no diagnosis (i.e. normoglycaemia) were used as a control group, n = 67. Distributions of breath acetone are presented for the different groups. There was no evidence of a direct relationship between blood glucose (BG) and acetone measurements at any time during the study (0 h: p = 0.4482; 1 h: p = 0.6854; and 2 h: p = 0.1858). Nor were there significant differences between the measurements of breath acetone for the control group and the T2DM group (0 h: p = 0.1759; 1 h: p = 0.4521; and 2 h: p = 0.7343). However, the ratio of breath acetone at 1 h to the initial breath acetone was found to be significantly different for the T2DM group compared to both the control and IGT groups (p = 0.0189 and 0.011, respectively). The T2DM group was also found to be different in terms of ratio of breath acetone after 1 h to that at 2 h during the OGTT. And was distinctive in that it showed a significant dependence upon the level of BG at 2 h (p = 0.0146). We conclude that single measurements of the concentrations of breath acetone cannot be used as a potential screening diagnostic for T2DM diabetes in this cohort, but monitoring the evolution of breath acetone could open a non-invasive window to aid in the diagnosis of metabolic conditions.


Asunto(s)
Acetona/análisis , Pruebas Respiratorias/métodos , Derivación y Consulta , Glucemia/metabolismo , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/diagnóstico , Femenino , Prueba de Tolerancia a la Glucosa , Guías como Asunto , Humanos , Hiperglucemia/sangre , Hiperglucemia/diagnóstico , Masculino , Persona de Mediana Edad , Modelos Biológicos
13.
Ergonomics ; 61(4): 482-505, 2018 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-29125389

RESUMEN

The capacity for superior vigilance can be trained by using knowledge of results (KR). Our present experiments demonstrate the efficacy of such training using a first-person perspective movement videogame-based platform in samples of students and Soldiers. Effectiveness was assessed by manipulating KR during a training phase and withdrawing it in a subsequent transfer phase. Relative to a no KR control condition, KR systematically improved performance for both Soldiers and students. These results build upon our previous findings that demonstrated that a video game-based platform can be used to create a movement-centred sustained attention task with important elements of traditional vigilance. The results indicate that KR effects in sustained attention extend to a first person perspective movement based paradigm, and that these effects occur in professional military as well as a more general population. Such sustained attention training can save lives and the present findings demonstrate one particular avenue to achieve this goal. Practitioner Summary: Sustained attention can be trained by means of knowledge of results using a videogame-based platform with samples of students and Soldiers. Four experiments demonstrate that a dynamic, first-person perspective video game environment can serve to support effective sustained attention training in professional military as well as a more general population.


Asunto(s)
Nivel de Alerta , Conocimiento Psicológico de los Resultados , Personal Militar , Entrenamiento Simulado , Estudiantes , Juegos de Video , Adolescente , Adulto , Atención , Femenino , Humanos , Masculino , Persona de Mediana Edad , Movimiento , Factores de Tiempo , Estados Unidos , Adulto Joven
14.
Sci Total Environ ; 601-602: 109-121, 2017 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-28550724

RESUMEN

Landscape Evolution Modelling (LEM) technologies provide a means by which it is possible to simulate the long-term geomorphic stability of a conceptual rehabilitated landform. However, simulations rarely consider the potential effects of anthropogenic climate change and consequently risk not accounting for the range of rainfall variability that might be expected in both the near and far future. One issue is that high resolution (both spatial and temporal) rainfall projections incorporating the potential effects of greenhouse forcing are required as input. However, projections of rainfall change are still highly uncertain for many regions, particularly at sub annual/seasonal scales. This is the case for northern Australia, where a decrease or an increase in rainfall post 2030 is considered equally likely based on climate model simulations. The aim of this study is therefore to investigate a spatial analogue approach to develop point scale hourly rainfall scenarios to be used as input to the CAESAR - Lisflood LEM to test the sensitivity of the geomorphic stability of a conceptual rehabilitated landform to potential changes in climate. Importantly, the scenarios incorporate the range of projected potential increase/decrease in rainfall for northern Australia and capture the expected envelope of erosion rates and erosion patterns (i.e. where erosion and deposition occurs) over a 100year modelled period. We show that all rainfall scenarios produce sediment output and gullying greater than that of the surrounding natural system, however a 'wetter' future climate produces the highest output. Importantly, incorporating analogue rainfall scenarios into LEM has the capacity to both improve landform design and enhance the modelling software. Further, the method can be easily transferred to other sites (both nationally and internationally) where rainfall variability is significant and climate change impacts are uncertain.

15.
Sci Total Environ ; 518-519: 189-200, 2015 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-25756674

RESUMEN

Pigs (Sus scrofa) are recognised as having significant ecological impacts in many areas of the world including northern Australia. The full consequences of the introduction of pigs are difficult to quantify as the impacts may only be detected over the long-term and there is a lack of quantitative information on the impacts of feral pigs globally. In this study the effect of feral pigs is quantified in an undisturbed catchment in the monsoonal tropics of northern Australia. Over a three-year period, field data showed that the areal extent of pig disturbance ranged from 0.3-3.3% of the survey area. The mass of material exhumed through these activities ranged from 4.3 t ha(-1) yr(-1) to 36.0 t ha(-1) yr(-1). The findings demonstrate that large introduced species such as feral pigs are disturbing large areas as well as exhuming considerable volumes of soil. A numerical landscape evolution and soil erosion model was used to assess the effect of this disturbance on catchment scale erosion rates. The modelling demonstrated that simulated pig disturbance in previously undisturbed areas produced lower erosion rates compared to those areas which had not been impacted by pigs. This is attributed to the pig disturbance increasing surface roughness and trapping sediment. This suggests that in this specific environment, disturbance by pigs does not enhance erosion. However, this conclusion is prefaced by two important caveats. First, the long term impact of soil disturbance is still very uncertain. Secondly, modelling results show a clear differentiation between those from an undisturbed environment and those from a post-mining landscape, in which pig disturbance may enhance erosion.


Asunto(s)
Monitoreo del Ambiente , Fenómenos Geológicos , Especies Introducidas , Modelos Teóricos , Suelo , Animales , Australia
16.
J Phys Chem A ; 119(23): 6045-56, 2015 Jun 11.
Artículo en Inglés | MEDLINE | ID: mdl-25656343

RESUMEN

The S1((1)ππ*) state of the (dominant) syn-conformer of 2-chlorophenol (2-ClPhOH) in the gas phase has a subpicosecond lifetime, whereas the corresponding S1 states of 3- and 4-ClPhOH have lifetimes that are, respectively, ∼2 and ∼3-orders of magnitude longer. A range of experimental techniques-electronic spectroscopy, ultrafast time-resolved photoion and photoelectron spectroscopies, H Rydberg atom photofragment translational spectroscopy, velocity map imaging, and time-resolved Fourier transform infrared emission spectroscopy-as well as electronic structure calculations (of key regions of the multidimensional ground (S0) state potential energy surface (PES) and selected cuts through the first few excited singlet PESs) have been used in the quest to explain these striking differences in excited state lifetime. The intramolecular O-H···Cl hydrogen bond specific to syn-2-ClPhOH is key. It encourages partial charge transfer and preferential stabilization of the diabatic (1)πσ* potential (relative to that of the (1)ππ* state) upon stretching the C-Cl bond, with the result that initial C-Cl bond extension on the adiabatic S1 PES offers an essentially barrierless internal conversion pathway via regions of conical intersection with the S0 PES. Intramolecular hydrogen bonding is thus seen to facilitate the type of heterolytic dissociation more typically encountered in solution studies.

17.
J Environ Radioact ; 140: 30-41, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25461513

RESUMEN

The Tertiary Limestone Aquifer (TLA) is one of the major regional hydrogeological systems of southern Australia. Submarine groundwater discharge (SGD) of freshwater from the TLA occurs through spring creeks, beach springs and diffusively through beach sands, but the magnitude of the total flux is not known. Here, a range of potential environmental tracers (including temperature, salinity, (222)Rn, (223)Ra, (224)Ra, (226)Ra, (228)Ra, and (4)He) were measured in potential sources of SGD and in seawater along a 45 km transect off the coastline to evaluate SGD from the TLA. Whilst most tracers had a distinct signature in the sources of water to the coastline, salinity and the radium quartet had the most distinct SGD signal in seawater. A one-dimensional advection-dispersion model was used to estimate the terrestrial freshwater component of SGD (Qfw) using salinity and the recirculated seawater component (Qrsw) using radium activity in seawater. Qfw was estimated at 1.2-4.6 m(3) s(-1), similar in magnitude to previously measured spring creek discharge (∼3 m(3) s(-1)) for the area. This suggests that other terrestrial groundwater discharge processes (beach springs and diffuse discharge through beach sands) were no more than 50% of spring creek discharge. The largest component of total SGD was Qrsw, estimated at 500-1000 m(3) s(-1) and possibly greater. The potential for wave, storm, or buoyancy-driven porewater displacement from the seafloor could explain the large recirculation flux for this section of the Southern Ocean Continental Shelf.


Asunto(s)
Agua Subterránea/análisis , Radio (Elemento)/análisis , Radón/análisis , Australia
18.
Opt Lett ; 38(14): 2475-7, 2013 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-23939085

RESUMEN

A cw distributed feedback quantum cascade laser (DFB-QCL) coupled to a two-mirror linear optical cavity has been used to successfully demonstrate optical-feedback cavity-enhanced absorption spectroscopy (OF-CEAS) at 5.5 µm. The noise-equivalent absorption coefficient, α(min), was 2.4×10(-8) cm(-1) for 1 s averaging, limited by etalon-fringing. The temporal stability of the instrument allows NO detection down to 5 ppb in 2 s.

19.
J Environ Radioact ; 107: 78-85, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22336567

RESUMEN

This paper summarizes key findings and identifies the main lessons learnt from a 5-year (2002-2008) coordinated research project (CRP) on "Assessing the effectiveness of soil conservation measures for sustainable watershed management and crop production using fallout radionuclides" (D1.50.08), organized and funded by the International Atomic Energy Agency through the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. The project brought together nineteen participants, from Australia, Austria, Brazil, Canada, Chile, China, Japan, Morocco, Pakistan, Poland, Romania, Russian Federation, Turkey, United Kingdom, United States of America and Vietnam, involved in the use of nuclear techniques and, more particularly, fallout radionuclides (FRN) to assess the relative impacts of different soil conservation measures on soil erosion and land productivity. The overall objective of the CRP was to develop improved land use and management strategies for sustainable watershed management through effective soil erosion control practices, by the use of ¹³7Cs (half-life of 30.2 years), ²¹°Pb(ex) (half-life of 22.3 years) and 7Be (half-life of 53.4 days) for measuring soil erosion over several spatial and temporal scales. The environmental conditions under which the different research teams applied the tools based on the use of fallout radionuclides varied considerably--a variety of climates, soils, topographies and land uses. Nevertheless, the achievements of the CRP, as reflected in this overview paper, demonstrate that fallout radionuclide-based techniques are powerful tools to assess soil erosion/deposition at several spatial and temporal scales in a wide range of environments, and offer potential to monitor soil quality. The success of the CRP has stimulated an interest in many IAEA Member States in the use of these methodologies to identify factors and practices that can enhance sustainable agriculture and minimize land degradation.


Asunto(s)
Contaminantes Radiactivos del Suelo/análisis , Berilio/análisis , Radioisótopos de Cesio/análisis , Conservación de los Recursos Naturales/métodos , Radioisótopos de Plomo/análisis , Ceniza Radiactiva/análisis , Radioisótopos/análisis
20.
Work ; 41 Suppl 1: 5882-5, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22317718

RESUMEN

Emotion-provoking stimuli abound on modern roadways. Driving measures, of both longitudinal and lateral control of the vehicle, have been shown to vary based on affective influences. Research, however, has yet to address how drivers' individual techniques to mitigate emotional reactions influence driving performance. To address this issue, the present study featured a dual-task protocol involving simulated driving together with processing of emotionally-valenced images with a focus on different Predominant Emotion Regulation Techniques (PERT): one adaptive strategy (task-focused coping) and one maladaptive style (emotion-focused coping). Dependent measures included mean driving speed and number of lane excursions. Results indicated that pleasant images degraded longitudinal control to the greatest extent, while unpleasant images produced the greatest detriment in lateral control. Additionally, individuals' PERT played a major interactive role in drivers' longitudinal control leading task-focused females and emotion-focused males to adhere more closely to the speed limit; yet, it did not affect their lateral control. Results hold important potential implications for the amount or variety of training necessary for driver licensure to promote and sustain safe vehicle control.


Asunto(s)
Adaptación Psicológica , Conducción de Automóvil , Control de la Conducta/métodos , Emociones , Análisis y Desempeño de Tareas , Femenino , Humanos , Masculino
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