bluuebunny/crossref_metadata_2025 huggingface dataset:
Reason, Freedom and Well-being
Authors: SEN AMARTYA
Published: February 2006

I am embarrassed at being placed in the dizzying company of one of the truly great thinkers in the world. The similarities between Mill's ideas and mine partly reflect, of course, his influence on my thinking. But I also discuss some difficulties in taking Mill's whole theory without modification, since there are internal tensions within it. In a paper I published in 1967, I tried to discuss how Mill's willingness to hold on to some contrary positions depended on the nature of his empirical reading of the world. I draw on that diagnosis in commenting on some of the articles here. There are some serious issues of misinterpretation in one of the articles, which I try to clarify. I also comment on Arrow's interpretation of what is involved in the idea of autonomy and on his own way of assessing freedom, and acknowledge the seriousness of the questions he raises about the value of freedom in normative political philosophy.
REVISION OF GREWIA (MALVACEAE–GREWIOIDEAE) IN PENINSULAR MALAYSIA AND BORNEO
Authors: CHUNG R. C. K.
Published: February 2006

Two keys to distinguish the genera Grewia and Microcos are presented, one based on macromorphological characters and the other on micromorphological characters. Grewia is revised for Peninsular Malaysia and Borneo. Despite the 33 names published under Grewia for the region only four species are recognized here. Grewia multiflora is newly recorded from Borneo and attention is drawn to its curious distribution; G. huluperakensis is endemic to Peninsular Malaysia; G. polygama is found in limestone forest in northern Peninsular Malaysia, and G. laevigata is common in Peninsular Malaysia and Borneo. A key, descriptions and illustrations are provided for all four species. A list of excluded species names is included: all are referable to Microcos.
KARYOTYPE STUDIES IN LYCIUM SECTIONS SCHISTOCALYX AND SCLEROCARPELLUM (SOLANACEAE)
Authors: STIEFKENS L. , BERNARDELLO G.
Published: February 2006

Mitotic chromosome numbers and karyotypes of species in two sections of Lycium (Solanaceae) from the American continent were determined in 23 populations. Both species in the small South American section Schistocalyx were examined: Lycium ciliatum and three varieties of L. chilense had diploid (2n=24) as well as tetraploid (2n=48) populations. Lycium ameghinoi from the small American section Sclerocarpellum was diploid with 2n=24. The basic number x=12 for the genus was confirmed. The karyotypes of these taxa were highly symmetrical: the chromosomes were metacentric or submetacentric with the formula: 11 m + 1 sm. Microsatellites were present in chromosome pair no. 1 and were attached to the short arms. As in other Lycium taxa already investigated, karyotypic features suggest that morphological differentiation in the group has not been accompanied by karyotype divergence.
INFLUENCE OF SOIL AND TOPOGRAPHY ON THE COMPOSITION OF A TREE COMMUNITY IN A CENTRAL BRAZILIAN VALLEY FOREST
Authors: PINTO J. R. R. , OLIVEIRA-FILHO A. T. , HAY J. D. V.
Published: February 2006

The purpose of the present study was to investigate the correlations between environmental variables related to the substrate (soil and topography) and the distribution of tree species in a valley forest in the Chapada dos Guimarães National Park, Mato Grosso State, Brazil. The forest lies in the Cerrado Domain of Central Brazil where the dominant vegetation cover is cerrado (woody savanna). A survey of the tree community registered all live individuals with circumference at breast height (cbh)≥15cm found in eighteen 600m2 plots (total area 1.08ha). The substrate variables used in the gradient analyses were obtained from a topographic survey and from analyses of the chemical and physical properties of soil samples. A principal components analysis of soil and topography variables and a canonical correspondence analysis of the species–environment relationships produced similar results, separating both the substrate variables and the tree species abundances, mainly according to the two types of bedrock, sandstone or slate, underlying their soils, and secondly to the three topographic sectors recognized: Streamside, Mid Slope and Upper Slope. The differences in soil fertility and texture (related to the bedrocks) and the soil water regime (related to both soil texture and topography) were probably the chief factors determining the distribution of tree species in the forest.
PHYLOGENY AND SPECIES RELATIONSHIPS IN JASIONE (CAMPANULACEAE) WITH EMPHASIS ON THE ‘MONTANA-COMPLEX’
Authors: PÉREZ-ESPONA S. , SALES F. , HEDGE I. , MÖLLER M.
Published: February 2006

The evolutionary relationships of several, mainly Iberian, Jasione taxa (Campanulaceae) were investigated using molecular data. A parsimony analysis of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA was partially successful in elucidating some interspecific alliances. One of the main clades included three morphologically rather disparate species from S Spain and Morocco which might indicate that these areas were refugia during the last glaciations. The fact that most of the other taxa fell in a large polytomy suggests a recent origin of these species. Amplified fragment length polymorphisms (AFLPs) were analysed for a larger sample set of two taxa from within the ITS polytomy to assess the partition of genetic variation between and within populations. All the British accessions named J. montana var. montana were found to be close to those so-named from Spain. However, individual accessions of J. montana var. montana from Argyll (Scotland), Devon (SW England) and the Shetland Islands proved to be genetically different from each other. This might suggest a low level of genetic diversification from a common progenitor due to a rapid northward migration. It is proposed that J. montana var. bracteosa and J. maritima var. sabularia merit recognition at higher rank. The possibility that J. montana vars gracilis and latifolia are mere repetitive segregants of J. montana var. montana is considered.
On the determination of a cloud condensation nuclei from satellite: Challenges and possibilities
Authors: Kapustin V. N. , Clarke A. D. , Shinozuka Y. , Howell S. , Brekhovskikh V. , Nakajima T. , Higurashi A.
Published: February 2006

We use aerosol size distributions measured in the size range from 0.01 to 10+ μm during Transport and Chemical Evolution over the Pacific (TRACE‐P) and Aerosol Characterization Experiment–Asia (ACE‐Asia), results of chemical analysis, measured/modeled humidity growth, and stratification by air mass types to explore correlations between aerosol optical parameters and aerosol number concentration. Size distributions allow us to integrate aerosol number over any size range expected to be effective cloud condensation nuclei (CCN) and to provide definition of a proxy for CCN (CCNproxy). Because of the internally mixed nature of most accumulation mode aerosol and the relationship between their measured volatility and solubility, this CCNproxy can be linked to the optical properties of these size distributions at ambient conditions. This allows examination of the relationship between CCNproxy and the aerosol spectral radiances detected by satellites. Relative increases in coarse aerosol (e.g., dust) generally add only a few particles to effective CCN but significantly increase the scattering detected by satellite and drive the Angstrom exponent (α) toward zero. This has prompted the use of a so‐called aerosol index (AI) on the basis of the product of the aerosol optical depth and the nondimensional α, both of which can be inferred from satellite observations. This approach biases the AI to be closer to scattering values generated by particles in the accumulation mode that dominate particle number and is therefore dominated by sizes commonly effective as CCN. Our measurements demonstrate that AI does not generally relate well to a measured proxy for CCN unless the data are suitably stratified. Multiple layers, complex humidity profiles, dust with very low α mixed with pollution, and size distribution differences in pollution and biomass emissions appear to contribute most to method limitations. However, we demonstrate that these characteristic differences result in predictable influences on AI. These results suggest that inference of CCN from satellites will be challenging, but new satellite and model capabilities could possibly be integrated to improve this retrieval.
Threshold relations in subsurface stormflow: 1. A 147‐storm analysis of the Panola hillslope
Authors: Tromp‐van Meerveld H. J. , McDonnell J. J.
Published: February 2006

Subsurface stormflow is a dominant runoff‐producing mechanism in many upland environments. While there have been many trench‐based experimental studies, most of these investigations have examined only a handful of storms. We analyzed subsurface stormflow in response to 147 rainstorms at a trenched hillslope in the Panola Mountain Research Watershed between February 1996 and May 1998. We used this unique long‐term data set to examine how often the hillslope delivers water, the contribution of pipe flow to total flow, and the persistence of spatial patterns of flow at the trench face. The long‐term data set showed a clear threshold response of subsurface stormflow to storm total precipitation. For storms smaller than the precipitation threshold of 55 mm, little subsurface stormflow was observed. For events exceeding the threshold, there was an almost 2 orders of magnitude increase in subsurface flow compared to subsurface flow from storms smaller than the threshold. Pipe flow was an important component of total subsurface flow and showed a similar threshold behavior. We observed a linear relation between total pipe flow and total subsurface stormflow. Contributions of different trench segments to total trench flow changed seasonally and with changes in precipitation and antecedent conditions. Our results suggest that the threshold relation at the hillslope scale may be an emergent behavior of combined processes internal to the hillslope and perhaps point the way toward how to characterize hillslope processes. A companion paper (Tromp‐van Meerveld and McDonnell, 2006) explores the physical mechanisms responsible for the threshold behavior.
Threshold relations in subsurface stormflow: 2. The fill and spill hypothesis
Authors: Tromp‐van Meerveld H. J. , McDonnell J. J.
Published: February 2006

Analysis of subsurface stormflow from 147 storms at the 20 m long trench in the Panola Mountain Research Watershed by Tromp‐van Meerveld and McDonnell (2006a) showed that there was a distinct 55 mm precipitation threshold for significant subsurface stormflow production. This second paper in the series investigates the processes responsible for this threshold response. We installed a dense spatial array of maximum rise crest stage gauges and recording wells on the hillslope and studied the temporal and spatial patterns of transient saturation at the soil‐bedrock interface and its relation to subsurface stormflow measured at the trench face. Results show that while transient groundwater developed on parts of the hillslope during events smaller than 55 mm, it was not until more than 55 mm of rain fell before bedrock depressions on the hillslope were filled, water spilled over microtopographic relief in the bedrock surface, and the subsurface saturated areas became connected to the trench. When connectivity was achieved, the instantaneous subsurface stormflow rate increased more than fivefold compared to before the subsurface saturated areas were connected to the trench face. Total subsurface stormflow was more than 75 times larger when connectivity was achieved compared to when connectivity was not achieved. The fill and spill hypothesis presented in this paper is a process explanation for the observed threshold behavior of Tromp‐van Meerveld and McDonnell (2006a), thereby linking patterns and processes.
Seasonal measurements of acetone and methanol: Abundances and implications for atmospheric budgets
Authors: Schade Gunnar W. , Goldstein Allen H.
Published: February 2006

Acetone and methanol have been measured hourly at a rural mountain site in California for a full year, providing a unique data set for analyzing the factors controlling their seasonal cycles. Their mixing ratios showed clear maxima in summer and late spring respectively, and were mostly correlated with atmospheric temperature with highest values during heat waves. Lowest values occurred during winter coincident with the periods of lowest temperature (0.15 ppb for acetone and 0.4 ppb for methanol). The acetone to methanol ratio changed seasonally with a minimum in spring and maxima in late summer and fall, likely reflecting higher springtime methanol emissions. The ratio was highest during fall and winter, probably a result of secondary acetone production from diffuse anthropogenic sources. Large decreases of both gases were observed when frontal passages brought free tropospheric air of Pacific origin to the site as indicated by back trajectory analysis. Neither wet nor dry deposition could explain these periodic decreases. Our results confirm previous assessments showing large acetone and methanol abundances over rural areas indicative of large biogenic sources. Their high degree of correlation at all times suggests a strong link between their biogenic emission sources and only a small influence of anthropogenic sources, at least at this site. The free tropospheric background mixing ratios concur with published measurements from aircraft over the Pacific, and are consistent with a substantial, diffuse source from hydrocarbon oxidation.
Mangroves, a major source of dissolved organic carbon to the oceans
Authors: Dittmar Thorsten , Hertkorn Norbert , Kattner Gerhard , Lara Rubén J.
Published: February 2006

Organic matter, which is dissolved in low concentrations in the vast waters of the oceans, contains a total amount of carbon similar to atmospheric carbon dioxide. To understand global biogeochemical cycles, it is crucial to quantify the sources of marine dissolved organic carbon (DOC). We investigated the impact of mangroves, the dominant intertidal vegetation of the tropics, on marine DOC inventories. Stable carbon isotopes and proton nuclear magnetic resonance spectroscopy showed that mangroves are the main source of terrigenous DOC in the open ocean off northern Brazil. Sunlight efficiently destroyed aromatic molecules during transport offshore, removing about one third of mangrove‐derived DOC. The remainder was refractory and may thus be distributed over the oceans. On a global scale, we estimate that mangroves account for >10% of the terrestrially derived, refractory DOC transported to the ocean, while they cover only <0.1% of the continents' surface.
A self‐regulating model of bedrock river channel geometry
Authors: Stark C. P.
Published: February 2006

The evolution of many mountain landscapes is controlled by the incision of bedrock river channels. While the rate of incision is set by channel shape through its mediation of flow, the channel shape is itself set by the history of bedrock erosion. This feedback between channel geometry and incision determines the speed of landscape response to tectonic or climatic forcing. Here, a model for the dynamics of bedrock channel shape is derived from geometric arguments, a normal flow approximation for channel flow, and a threshold bed shear stress assumption for bedrock abrasion. The model dynamics describe the competing effects of channel widening, tilting, bending, and variable flow depth. Transient solutions suggest that channels may take ∼1–10 ky to adapt to changes in discharge, implying that channel disequilibrium is commonplace. If so, landscape evolution models will need to include bedrock channel dynamics if they are to probe the effects of climate change.
Forward modeling of regional scale tree‐ring patterns in the southeastern United States and the recent influence of summer drought
Authors: Anchukaitis K. J. , Evans M. N. , Kaplan A. , Vaganov E. A. , Hughes M. K. , Grissino‐Mayer H. D. , Cane M. A.
Published: February 2006

We use a mechanistic model of tree‐ring formation to simulate regional patterns of climate‐tree growth relationships in the southeastern United States. Modeled chronologies are consistent with actual tree‐ring data, demonstrating that our simulations have skill in reproducing broad‐scale patterns of the proxy's response to climate variability. The model predicts that a decrease in summer precipitation, associated with a weakening Bermuda High, has become an additional control on tree ring growth during recent decades. A nonlinear response of tree growth to climate variability has implications for the calibration of tree‐ring records for paleoclimate reconstructions and the prediction of ecosystem responses to climate change.
ASIRAS airborne radar resolves internal annual layers in the dry‐snow zone of Greenland
Authors: Hawley R. L. , Morris E. M. , Cullen R. , Nixdorf U. , Shepherd A. P. , Wingham D. J.
Published: February 2006

We present data from the European Space Agency's Airborne SAR/Interferometric Radar Altimeter System (ASIRAS), flown during the CryoVex 2004 field calibration/validation campaign, and new, high‐resolution depth profiles of snow density measured in the field by neutron scattering. We combine these data to calculate the depth of internal reflecting horizons in the ASIRAS data. The high resolution density data allow us to identify annual layers in the snow density profile, and correlate their peaks with the reflecting horizons. We use the thickness of the annual layers combined with the density profile to determine the spatial and temporal pattern of snow accumulation along the radar track, for a period of 6 years from 1995–2002. Our mean‐annual accumulation rate is 0.47 ± 0.09 ma−1 water equivalent, in agreement with the value determined from a core taken in this location in 1992. Similarly, our inter‐annual variability shows the same trends as recent model estimates over the entire ice sheet. Because ASIRAS was designed to mimic as closely as possible the characteristics of the SAR/Interferometric Radar Altimeter (SIRAL), the principal payload of CryoSat, the detection of internal layering with ASIRAS illuminates the possibility of detecting internal layers with a space‐borne radar, and thus the possible application of this technique to the dry‐snow zones of Antarctica, Greenland, and smaller ice bodies.
Temporal signatures of radiation belt electron precipitation induced by lightning‐generated MR whistler waves: 1. Methodology
Authors: Bortnik J. , Inan U. S. , Bell T. F.
Published: February 2006

We present a novel technique designed to calculate the detailed differential number flux signature (as a function of energy and time) of precipitating radiation‐belt electrons, driven by a magnetospherically reflecting (MR) whistler wave, initiated by a single cloud‐to‐ground lightning discharge. Our model consists of several stages. First, we calculate the MR whistler wave characteristics at 1° latitude intervals along a given field‐line. This is accomplished using an extensive ray tracing and interpolation algorithm involving ∼120 million rays, and accounting for the effects of Landau damping, spatial, and temporal dispersion. We then use these wave characteristics to compute the pitch angle changes of resonant electrons by assuming that the interactions are linear, and independent between adjacent latitude and wave frequency bins. The pitch angle changes are transformed to precipitating flux using a novel convolution method and displayed as a function of particle energy and time at the feet of a given field line. We have calculated and compared the differential number flux signatures at the northern and southern feet of the L = 2.3 and L = 3 field lines, and found that precipitation onset and duration times increase with latitude (consistent with previous work). The precipitation consists of suprathermal Landau resonance electrons (E ≲ 10 keV) which are intense but contribute little to the total energy flux, a flux gap (10 keV ≲ E ≲ 80 keV) corresponding to a change in coupling mechanism from Landau resonance to gyroresonance, and a series of precipitation swaths (E ≳ 80 keV) corresponding to gyroresonance interactions. The swaths result in periodic maxima in the precipitated energy flux, which correspond to the equatorial traversals of the underlying MR whistler wave energy. Global precipitation signatures were computed for a number of lightning discharge latitudes and are presented in a companion paper (Bortnik et al., 2006).
Temporal signatures of radiation belt electron precipitation induced by lightning‐generated MR whistler waves: 2. Global signatures
Authors: Bortnik J. , Inan U. S. , Bell T. F.
Published: February 2006

We use the methodology presented in a companion paper to calculate the temporal and spatial precipitation signatures of energetic radiation‐belt electrons due to pitch‐angle scattering by magnetospherically reflecting (MR) whistler waves generated by lightning discharges at geomagnetic source latitudes of λs = 25°, 35°, 45°, and 55°. We show precipitated energy and number fluxes, as well as average precipitated energy as a function of time and L‐shell for all four λs cases, and then extrapolate the results of the λs = 35° case in longitude to produce a time‐sequence of geographic ‘hot spots’ which are affected by the MR whistler induced electron precipitation. We then discuss the total precipitation in both hemispheres due to the various λs cases. Our major findings are that the precipitation region moves to higher L‐shells as a function of time, on short (0.1 sec, at the start of the event) and long (10 sec) timescales, corresponding to the first hop of the wave, and the MR portion of the whistler wave, respectively. There is also structure within the long‐timescale precipitation on the order of ∼1 sec, reflecting the periodic MR of the underlying whistler wave. As λs increases, an additional precipitated flux signature which is more incoherent and discontinuous, begins to form at higher L‐shells and later times, due to MR whistler wave reflections from the plasmapause. At lower L‐shells, a pronounced maximum occurs in the number flux of ∼1 keV electrons at L ∼ 2–3 due to the Landau resonance. The geographic hot spot affected by the precipitation can split into two separate regions per hemisphere, and occur simultaneously in both hemispheres so that up to four distinct precipitation hot spots can occur on the Earth at any instant, driven by a single lightning discharge. We also discuss potential sources of error, and comparison to related modeling efforts, and to observations using a either satellite‐borne instruments or ground‐based techniques.
Comparison of GPS and ERA40 IWV in the Alpine region, including correction of GPS observations at Jungfraujoch (3584 m)
Authors: Morland J. , Liniger M. A. , Kunz H. , Balin I. , Nyeki S. , Mätzler C. , Kämpfer N.
Published: February 2006

The 31 stations in the Global Positioning System (GPS) network of Switzerland span an altitude range of 330 to 3584 m. The highest station in the network, Jungfraujoch, suffers from a constant negative bias in the Integrated Water Vapor (IWV) due to a protective radome. We compared Jungfraujoch GPS IWV measurements with coincident Precision Filter Radiometer (PFR) observations and showed that the bias in the GPS is fairly constant with respect to the time of year and to the PFR IWV value. A correction was developed for the GPS data and validated by comparison with coincident Raman lidar observations. The IWV observations from nine GPS stations, including Jungfraujoch, were then compared with the IWV field of the ECMWF 40 year reanalysis (ERA40) data. Altitude differences between the ERA40 surface level and the GPS stations resulted, as expected, in a positive bias in the ERA40 IWV. A fairly linear relationship, with an intercept of −0.3 mm, was found between this bias and the difference between the ERA40 surface pressure and the surface pressure at the GPS station. The ERA40 reanalysis captured water vapor variations on timescales of several days very well, as evidenced by an r2 correlation greater than 0.9 where the altitude difference between ERA40 and the GPS station was less than 1000 m. A comparison between ERA40 and GPS at Davos showed that the reanalysis underestimates IWV during winter temperature inversions.
Sulfate deposition in subsurface regolith in Gusev crater, Mars
Authors: Wang Alian , Haskin L. A. , Squyres S. W. , Jolliff B. L. , Crumpler L. , Gellert R. , Schröder C. , Herkenhoff K. , Hurowitz J. , Tosca N. J. , Farrand W. H. , Anderson Robert , Knudson A. T.
Published: February 2006

Excavating into the shallow Martian subsurface has the potential to expose stratigraphic layers and mature regolith, which may hold a record of more ancient aqueous interactions than those expected under current Martian surface conditions. During the Spirit rover's exploration of Gusev crater, rover wheels were used to dig three trenches into the subsurface regolith down to 6–11 cm depth: Road Cut, the Big Hole, and The Boroughs. A high oxidation state of Fe and high concentrations of Mg, S, Cl, and Br were found in the subsurface regolith within the two trenches on the plains, between the Bonneville crater and the foot of Columbia Hills. Data analyses on the basis of geochemistry and mineralogy observations suggest the deposition of sulfate minerals within the subsurface regolith, mainly Mg‐sulfates accompanied by minor Ca‐sulfates and perhaps Fe‐sulfates. An increase of Fe2O3, an excess of SiO2, and a minor decrease in the olivine proportion relative to surface materials are also inferred. Three hypotheses are proposed to explain the geochemical trends observed in trenches: (1) multiple episodes of acidic fluid infiltration, accompanied by in situ interaction with igneous minerals and salt deposition; (2) an open hydrologic system characterized by ion transportation in the fluid, subsequent evaporation of the fluid, and salt deposition; and (3) emplacement and mixing of impact ejecta of variable composition. While all three may have plausibly contributed to the current state of the subsurface regolith, the geochemical data are most consistent with ion transportation by fluids and salt deposition as a result of open‐system hydrologic behavior. Although sulfates make up >20 wt.% of the regolith in the wall of The Boroughs trench, a higher hydrated sulfate than kieserite within The Boroughs or a greater abundance of sulfates elsewhere than is seen in The Boroughs wall regolith would be needed to hold the structural water indicated by the water‐equivalent hydrogen concentration observed by the Gamma‐Ray Spectrometer on Odyssey in the Gusev region.
Temperature and carbonate ion effects on Mg/Ca and Sr/Ca ratios in benthic foraminifera: Aragonitic species Hoeglundina elegans
Authors: Rosenthal Yair , Lear Caroline H. , Oppo Delia W. , Linsley Braddock K.
Published: February 2006

Core top samples from Atlantic (Little Bahama Banks (LBB)) and Pacific (Hawaii and Indonesia) depth transects have been analyzed in order to assess the influence of bottom water temperature (BWT) and aragonite saturation levels on Mg/Ca and Sr/Ca ratios in the aragonitic benthic foraminifer Hoeglundina elegans. Both the Mg/Ca and Sr/Ca ratios in H. elegans tests show a general decrease with increasing water depth. Although at each site the decreasing trends are consistent with the in situ temperature profile, Mg/Ca and Sr/Ca ratios in LBB are substantially higher than in Indonesia and Hawaii at comparable water depths with a greater difference observed with increasing water depth. Because we find no significant difference between results obtained on “live” and “dead” specimens, we propose that these differences are due to primary effects on the metal uptake during test formation. Evaluation of the water column properties at each site suggests that in situ CO3 ion concentrations play an important role in determining the H. elegans Mg/Ca and Sr/Ca ratios. The CO3 ion effect is limited, however, only to aragonite saturation levels ([ΔCO3]aragonite) below 15 μmol kg−1. Above this level, temperature exerts a dominant effect. Accordingly, we propose that Mg/Ca and Sr/Ca in H. elegans tests can be used to reconstruct thermocline temperatures only in waters oversaturated with respect to the mineral aragonite using the following relationships: Mg/Ca = (0.034 ± 0.002)BWT + (0.96 ± 0.03) and Sr/Ca = (0.060 ± 0.002)BWT + (1.53 ± 0.03) (for [ΔCO3]aragonite > 15 μmol kg−1). The standard error associated with these equations is about ±1.1°C. Reconstruction of deeper water temperatures is complicated because in undersaturated waters, changes in Mg/Ca and Sr/Ca ratios reflect a combination of changes in [CO3] and BWT. Overall, we find that Sr/Ca, rather than Mg/Ca, in H. elegans may be a more accurate proxy for reconstructing paleotemperatures.
Multicentennial‐scale hydrological changes in the Black Sea and northern Red Sea during the Holocene and the Arctic/North Atlantic Oscillation
Authors: Lamy Frank , Arz Helge W. , Bond Gérard C. , Bahr André , Pätzold Jürgen
Published: February 2006

Paleoenvironmental proxy data for ocean properties, eolian sediment input, and continental rainfall based on high‐resolution analyses of sediment cores from the southwestern Black Sea and the northernmost Gulf of Aqaba were used to infer hydroclimatic changes in northern Anatolia and the northern Red Sea region during the last ∼7500 years. Pronounced and coherent multicentennial variations in these records reveal patterns that strongly resemble modern temperature and rainfall anomalies related to the Arctic Oscillation/North Atlantic Oscillation (AO/NAO). These patterns suggest a prominent role of AO/NAO–like atmospheric variability during the Holocene beyond interannual to interdecadal timescales, most likely originating from solar output changes.
Robust optimization for total maximum daily load allocations
Authors: Jia Yanbing , Culver Teresa B.
Published: February 2006

The determination of the pollutant load distribution among different pollutant sources in a watershed is a critical step in total maximum daily load (TMDL) development. Under current TMDL practices, TMDL allocations are typically determined through a trial‐and‐error approach of reducing pollutant loadings until a watershed simulation model predicts that water quality standards will be met given a margin of safety. Unfortunately, many feasible combinations of load reductions and significant uncertainties may exist. Therefore it is difficult and time‐consuming to compare various allocation scenarios using a trial‐and‐error approach. A robust optimization model is developed in this study to incorporate the uncertainty of water quality predictions and to minimize pollutant load reductions given various levels of reliability with respect to the water quality standards. The generalized likelihood uncertainty estimation approach is used to explicitly address the uncertainty of a watershed simulation model, the Hydrological Simulation Program–Fortran. The uncertainty is integrated into TMDL allocations using a robust genetic algorithm model linked with a response matrix approach. The developed robust optimization model is demonstrated using a case study based on the Moore's Creek fecal coliform TMDL study. The trade‐offs between reliability levels and total load reductions of allocation scenarios are evaluated, and the optimized load reduction scenarios are compared with the scenario generated by a trial‐and‐error approach and approved by the U.S. Environmental Protection Agency. The results show that the optimized load reduction scenario requires 30% less load reductions than the scenario approved by the U.S. Environmental Protection Agency at the same reliability level.
A process‐based rejectionist framework for evaluating catchment runoff model structure
Authors: Vaché Kellie B. , McDonnell Jeffrey J.
Published: February 2006

Complex hydrological descriptions at the hillslope scale have been difficult to incorporate within a catchment modeling framework because of the disparity between the scale of measurements and the scale of model subunits. As a result, parameters represented in many conceptual models are often not related to physical properties and therefore cannot be established prior to a model calibration. While tolerable for predictions involving water quantity, water quality simulations require additional attention to transport processes, flow path sources, and water age. This paper examines how isotopic estimates of residence time may be used to subsume flow path process complexity and to provide a simple, scalable evaluative data source for water quantity‐ and quality‐based conceptual models. We test a set of simple distributed hydrologic models (from simple to more complex) against measured discharge and residence time and employ a simple Monte Carlo framework to evaluate the identifiability of parameters and how the inclusion of residence time contributes to the evaluative process. Results indicate that of the models evaluated, only the most complex, including an explicit unsaturated zone volume and an effective porosity, successfully reproduced both discharge dynamics and residence time. In addition, the inclusion of residence time in the evaluation of the accepted models results in a reduction of the a posteriori parameter uncertainty. Results from this study support the conclusion that the incorporation of soft data, in this case, isotopically estimated residence times, in model evaluation is a useful mechanism to bring experimental evidence into the process of model evaluation and selection, thereby providing one mechanism to further reconcile hillslope‐scale complexity with catchment‐scale simplicity.
Known regulators of nitric oxide synthase and arginase are agonists at the human G‐protein‐coupled receptor GPRC6A
Authors: Christiansen Bolette , Wellendorph Petrine , Bräuner‐Osborne Hans
Published: February 2006

GPRC6A is a novel family C G‐protein‐coupled receptor (GPCR) with so far unknown physiological function. It was the aim of our study to further characterize the ligand preferences of the receptor and elucidate structural requirements for activity.

We have previously generated a functional chimeric receptor construct, h6A/5.24, containing the ligand‐binding amino‐terminal domain of the human GPRC6A and the seven‐transmembrane domain and carboxy terminus of the homologous goldfish receptor 5.24. Based on knowledge that this chimera prefers basic L‐α‐amino acids such as arginine, lysine and ornithine, we searched for commercially available analogues of these and other L‐α‐amino acids, and tested them for activity in a fluorescence‐based calcium assay. The majority of the tested compounds are involved in the regulation of nitric oxide synthase (NOS) and arginase enzymes. Altogether we profiled 30 different analogues.

We found that a structurally wide range of L‐α‐amino‐acid analogues of both arginine, lysine, and ornithine are agonists at h6A/5.24, whereas no antagonists were identified. From the profiling it is concluded that L‐α‐amino acids containing a highly basic side chain confer the highest activity, although the most potent compound was only twice as potent as L‐arginine, which has a EC50 value of 23.5 μM.

The reported agonism of NOS‐ and arginase‐active compounds at GPRC6A has obvious implications in interpretation of experiments involving the NOS and arginase systems, and interfering effects at GPRC6A should be regarded of relevance, especially as the physiological function of the receptor is not yet understood.

British Journal of Pharmacology (2006) 147, 855–863. doi:10.1038/sj.bjp.0706682
Common ligands of G‐protein‐coupled receptors and arginine‐utilizing enzymes
Authors: Hrabák András
Published: February 2006

A new family of G‐protein‐coupled receptors (GPRC6A) has recently been described and characterized with unknown physiological role. Three isoforms of GPRC6A are expressed from the same gene by alternative splicing. Agonists for GPRC6A are basic amino acids, particularly the analogues and derivatives of L‐arginine and L‐ornithine. These compounds are known ligands of nitric oxide synthase and arginase isoenzymes, but amino‐acid sequences of these enzymes have not shown significant homologies. Various hypotheses for physiological roles of these receptors have been proposed but not yet substantiated. In order to define the most potent agonists, and elucidate further the biological significance of the receptor family, a detailed ligand‐based quantitative structure–activity relationship study may be helpful.

British Journal of Pharmacology (2006) 147, 835–837. doi:10.1038/sj.bjp.0706683
Delta opioid receptor ligands modulate anxiety‐like behaviors in the rat
Authors: Perrine Shane A , Hoshaw Brian A , Unterwald Ellen M
Published: February 2006

The role of the delta opioid receptor in regulating anxiety‐like behavior in male Sprague–Dawley rats was examined.

Using an elevated plus maze, the effects of the selective delta opioid receptor antagonist naltrindole (1 or 5 mg kg−1) and agonist SNC80 (1, 5 or 20 mg kg−1) on anxiety‐like behavior were measured. Anxiety was also measured following administration of diazepam (3 mg kg−1) and amphetamine (1 mg kg−1) and compared to the effects of SNC80. Locomotor activity following administration of naltrindole, SNC80, diazepam, and amphetamine was measured. Finally, the defensive burying paradigm was used to confirm the findings from the elevated plus maze.

Results demonstrated that SNC80 produced dose‐dependent anxiolytic effects similar to that of the classical antianxiety agent, diazepam. Administration of naltrindole caused anxiogenic behavior in rats further supporting the involvement of the delta opioid receptor system in regulating anxiety. Naltrindole also blocked the anxiolytic effects of SNC80. Amphetamine had no effect on anxiety‐like behavior. SNC80 induced hyperactivity similar to amphetamine at the doses tested, while naltrindole and diazepam did not significantly affect locomotor activity.

Although SNC80 can increase locomotor activity, control experiments reported herein indicate that hyperlocomotion is not sufficient to produce an anxiolytic response on the elevated plus maze. Together with the results from the defensive burying paradigm, this suggests that the effects of SNC80 on reducing anxiety are independent of its effects on locomotion. Collectively these data show that the delta opioid receptor system can regulate anxiety‐like behavior in an anxiolytic (agonist) and anxiogenic (antagonist) manner.

British Journal of Pharmacology(2006)147, 864–872. doi:10.1038/sj.bjp.0706686
Effects of MDMA, MDA and MDEA on blood pressure, heart rate, locomotor activity and body temperature in the rat involveα‐adrenoceptors
Authors: Bexis Sotiria , Docherty James R
Published: February 2006

The effects of injection of 3,4‐methylenedioxymethamphetamine (MDMA), 3,4‐methylenedioxyamphetamine (MDA) andN‐ethyl‐3,4‐methylenedioxyamphetamine (MDEA) (all 20 mg kg−1) on blood pressure, heart rate, core body temperature and locomotor activity in conscious rats were investigated using radiotelemetry.

MDMA and MDA produced a prolonged increase in both systolic and diastolic pressures, with MDA causing the most marked rise. MDEA produced a transient but nonsignificant fall in diastolic pressure. The pressor response produced by MDA was accompanied by bradycardia.

All three amphetamine derivatives caused an initial hypothermic response; however, MDA also produced a subsequent hyperthermia, and the speed of recovery from hypothermia was MDA>MDMA>MDEA. Theα2A‐adrenoceptor antagonist 2‐((4,5‐dihydro‐1H‐imidazol‐2‐yl)methyl)‐2,3‐dihydro‐1‐methyl‐1H‐isoindole (BRL 44408) (1 mg kg−1) prolonged the hypothermic response to MDMA.

Only MDA induced locomotor activity when given alone, but in the presence of BRL 44408, MDMA produced increased locomotor activity.

The order of potency for producing isometric contractions of rat aorta (α1D) and vas deferens (α1A) was MDA>MDMA>MDEA, with MDEA acting as anα1‐adrenoceptor antagonist with a pKBof 4.79±0.12 (n=4) in aorta.

The order of potency for prejunctional inhibition of stimulation‐evoked contractions in rat vas deferens (α2A‐adrenoceptor mediated) was MDA>MDMA>MDEA.

Blood pressure actions of the three amphetamine derivatives may be at least partly due toα1‐adrenoceptor agonism or antagonism. The reversal of the hypothermic actions are at least partly due toα2A‐adrenoceptor agonism since the hypothermic response was more prolonged with MDEA which exhibits lowα2A‐adrenoceptor potency, and effects of MDMA afterα2A‐adrenoceptor antagonism were similar to those of MDEA.

British Journal of Pharmacology(2006)147, 926–934. doi:10.1038/sj.bjp.0706688
Cholecystokinin 1 receptor modulates the MEKK1‐induced c‐Jun trans‐activation: structural requirements of the receptor
Authors: Ibarz Géraldine , Oiry Catherine , Carnazzi Eric , Crespy Philippe , Escrieut Chantal , Fourmy Daniel , Galleyrand Jean Claude , Gagne Didier , Martinez Jean
Published: February 2006

In cells overexpressing active MEKK1 to enhance c‐Jun trans‐activation, expression of rat cholecystokinin 1 receptor increased the activity of c‐Jun while in the same experimental conditions overexpression of mouse cholecystokinin 1 receptor repressed it.

This differential trans‐activation is specific, since it was not observed for either the other overexpressed kinases (MEK, PKA) or for other transcription factors (ATF2, ELK‐1, CREB). This differential behaviour was also detected in a human colon adenocarcinoma cell‐line naturally producing high levels of endogenous MEKK1.

This differential behaviour between the two receptors on the MEKK1‐induced c‐Jun trans‐activation was independent of the activation state of JNK, of the phosphorylation level of c‐Jun and of its ability to bind its specific DNA responsive elements.

Two amino acids (Val43 and Phe50 in the mouse cholecystokinin 1 receptor, replaced by Leu43 and Ileu50 in the rat cholecystokinin 1 receptor) localized in the first transmembrane domain were found to play a crucial role in this differential behaviour.

MEKK1 probably activates a transcriptional partner of c‐Jun whose activity is maintained or increased in the presence of the rat cholecystokinin 1 receptor but repressed in the presence of the mouse cholecystokinin 1 receptor.

British Journal of Pharmacology(2006)147, 951–958. doi:10.1038/sj.bjp.0706690
L‐β,β‐Dimethylcysteine attenuates the haemodynamic responses elicited by systemic injections of peroxynitrite in anaesthetized rats
Authors: Graves Jonathan E , Kooy Neil W , Lewis Stephen J
Published: February 2006

There is direct chemical evidence that L‐β,β‐dimethylcysteine (L‐penicillamine (L‐PEN)) is a scavenger of peroxynitrite. The aim of this study was to determine whether L‐PEN attenuates the haemodynamic responses elicited by peroxynitrite in pentobarbital‐anaesthetized rats.

Peroxynitrite (1–20 μmol kg−1, i.v.) elicited dose‐dependent reductions in mean arterial blood pressure (MAP) and mesenteric and hindquarter vascular resistances.

L‐PEN (2 mmol kg−1, i.v.) elicited relatively minor but significant increases in MAP and vascular resistances. The initial reductions in MAP and vascular resistances elicited by peroxynitrite were not diminished after administration of L‐PEN whereas they were much shorter in duration. As such, the total reductions in MAP and vascular resistances were markedly reduced by L‐PEN.

The finding that L‐PEN (2 mmol kg−1, i.v.) did not affect the hypotensive or vasodilator responses elicited of the ATP‐dependent potassium‐channel agonist, cromakalim (3–18 μg kg−1, i.v.), suggests that this dose of L‐PEN is not a nonselective inhibitor of vasodilation.

These findings suggest that L‐PEN may effectively scavenge peroxynitrite in vivo and/or interfere with the mechanisms by which peroxynitrite elicits its vasodilator responses.

British Journal of Pharmacology (2006) 148, 7–15. doi:10.1038/sj.bjp.0706692
Peroxynitrite: just an oxidative/nitrosative stressor or a physiological regulator as well?
Authors: Ferdinandy Péter
Published: February 2006

British Journal of Pharmacology (2006) 148, 1–3. doi:10.1038/sj.bjp.0706693
Upregulation of tachykinin NK‐1 and NK‐3 receptor binding sites in the spinal cord of spontaneously hypertensive rat: impact on the autonomic control of blood pressure
Authors: Cloutier Frank , Ongali Brice , Deschamps Kathleen , Brouillette Jonathan , Neugebauer Witold , Couture Réjean
Published: February 2006

Effects of intrathecally (i.t.) injected tachykinin NK‐1 and ‐3 receptor agonists and antagonists were measured on mean arterial blood pressure (MAP) and heart rate (HR) in awake unrestrained spontaneously hypertensive rats (SHR,15‐week‐old) and age‐matched Wistar Kyoto rats (WKY). Quantitativein vitroautoradiography was also performed on the lower thoracic spinal cord of both strains and Wistar rats using specific radioligands for NK‐1 receptor ([125I]HPP[Arg3,Sar9,Met(O2)11]SP (3–11)) and NK‐3 receptor ([125I]HPP‐Asp‐Asp‐Phe‐N‐MePhe‐Gly‐Leu‐Met‐NH2).

The NK‐1 agonist [Sar9,Met(O2)11]SP (650 and 6500 pmol) decreased MAP and increased HR in WKY. The fall in MAP was blunted in SHR and substituted by increases in MAP (65–6500 pmol) and more sustained tachycardia. The NK‐3 agonist senktide (6.5–65 pmol) evoked marked increases in MAP and HR (SHR>>>WKY), yet this response was rapidly desensitized. Cardiovascular effects of [Sar9,Met(O2)11]SP (650 pmol) and senktide (6.5 pmol) were selectively blocked by the prior i.t. injection of LY303870 (NK‐1 antagonist, 65 nmol) and SB235375 (NK‐3 antagonist, 6.5 nmol), respectively. Antagonists had no direct effect on MAP and HR in both strains.

Densities of NK‐1 and ‐3 receptor binding sites were significantly increased in all laminae of the spinal cord in SHR when compared to control WKY and Wistar rats. The dissociation constant was however not affected in SHR for both NK‐1 (Kd=2.5 nM) and NK‐3 (Kd=5 nM) receptors.

Data highlight an upregulation of NK‐1 and ‐3 receptor binding sites in the thoracic spinal cord of SHR that may contribute to the hypersensitivity of the pressor response to agonists and to the greater sympathetic activity seen in this model of arterial hypertension.

British Journal of Pharmacology(2006)148, 25–38. doi:10.1038/sj.bjp.0706694
Nitric oxide‐releasing flurbiprofen reduces formation of proinflammatory hydrogen sulfide in lipopolysaccharide‐treated rat
Authors: Anuar Farhana , Whiteman Matthew , Siau Jia Ling , Kwong Shing Erl , Bhatia Madhav , Moore Philip K
Published: February 2006

The biosynthesis of both nitric oxide (NO) and hydrogen sulfide (H2S) is increased in lipopolysaccharide (LPS)‐injected mice and rats but their interaction in these models is not known. In this study we examined the effect of the NO donor, nitroflurbiprofen (and the parent molecule flurbiprofen) on NO and H2S metabolism in tissues from LPS‐pretreated rats.

Administration of LPS (10 mg kg−1, i.p.; 6 h) resulted in an increase (P<0.05) in plasma TNF‐α, IL‐1β and nitrate/nitrite (NOx) concentrations, liver H2S synthesis (from added cysteine), CSE mRNA, inducible nitric oxide synthase (iNOS), myeloperoxidase (MPO) activity (marker for neutrophil infiltration) and nuclear factor‐kappa B (NF‐κB) activation.

Nitroflurbiprofen (3–30 mg kg−1, i.p.) administration resulted in a dose‐dependent inhibition of the LPS‐mediated increase in plasma TNF‐α, IL‐1β and NOx concentration, liver H2S synthesis (55.00±0.95 nmole mg protein−1, c.f. 62.38±0.47 nmole mg protein−1, n=5, P<0.05), CSE mRNA, iNOS, MPO activity and NF‐κB activation.

Flurbiprofen (21 mg kg−1, i.p.) was without effect.

These results show for the first time that nitroflurbiprofen downregulates the biosynthesis of proinflammatory H2S and suggest that such an effect may contribute to the augmented anti‐inflammatory activity of this compound.

These data also highlight the existence of ‘crosstalk’ between NO and H2S in this model of endotoxic shock.

British Journal of Pharmacology (2006) 147, 966–974. doi:10.1038/sj.bjp.0706696