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Upward
Terms modified by Upward Selected AbstractsPositioning of salt gradients in ion-exchange SMBAICHE JOURNAL, Issue 3 2003Joukje Houwing Salt gradients can be used to improve the efficiency of ion-exchange separations in simulated moving-bed systems. The gradient, formed by the use of feed and desorbent solutions of different salt concentrations, introduces regions of increased and decreased affinity of, for example, proteins for the matrix. Several gradient shapes can be formed, depending on the flow-rate ratios and salt concentrations used. Only some of these effectively increase throughput or decrease desorbent consumption. Correct gradient positioning is essential, but not trivial, because salt is adsorbed in the resin. A procedure developed selects the flow-rate ratios that allow correct positioning of gradients based on wave theory and incorporates the nonlinear Donnan isotherm of salt on ion-exchange resins. Predictions are verified by experiments combined with a mathematical equilibrium stage (true moving-bed) model. Upward and downward gradients are compared with respect to the use of desorbent and salt. [source] Gas-solid Two-phase Mixtures Flowing Upward through a Confined Packed Bed,PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 3-4 2006Yurong He Abstract This paper deals with flows of a gas-solid two-phase mixture through a confined packed bed. Both experimental work and numerical modelling are performed on the behaviour of suspended particles within the packed bed. The experimental work is carried out with a non-intrusive Positron Emission Particle Tracking (PEPT) technique, which tracks particle motion at the single particle level for a prolonged period thus allows both the microscopic and macroscopic solids behaviour to be analysed under the steady-state conditions. A continuous based model is used to simulate the flow behaviour. The model uses a newly proposed porosity model and treats the suspended and packed particles as a binary mixture with the packed particles being at zero velocity. The results show that the model captures the main features of solids behaviour in terms of the radial distributions of the suspended particle concentration and the axial solids velocity. Both the experiments and modelling suggest that the wall effect on the motion of suspended particles be limited to a small region close to the wall (,0.5,1 packed particle diameter). However, deviations exist between the model predictions and experiments; more work is therefore proposed to improve the interaction terms in the model between the suspended and packed particles. [source] Granularity in Relational Formalisms,With Application to Time and Space RepresentationCOMPUTATIONAL INTELLIGENCE, Issue 4 2001Jérôme Euzenat Temporal and spatial phenomena can be seen at a more or less precise granularity, depending on the kind of perceivable details. As a consequence, the relationship between two objects may differ depending on the granularity considered. When merging representations of different granularity, this may raise problems. This paper presents general rules of granularity conversion in relation algebras. Granularity is considered independently of the specific relation algebra, by investigating operators for converting a representation from one granularity to another and presenting six constraints that they must satisfy. The constraints are shown to be independent and consistent and general results about the existence of such operators are provided. The constraints are used to generate the unique pairs of operators for converting qualitative temporal relationships (upward and downward) from one granularity to another. Then two fundamental constructors (product and weakening) are presented: they permit the generation of new qualitative systems (e.g. space algebra) from existing ones. They are shown to preserve most of the properties of granularity conversion operators. [source] UNITED STATES V. BOOKER AS A NATURAL EXPERIMENT: USING EMPIRICAL RESEARCH TO INFORM THE FEDERAL SENTENCING POLICY DEBATE,CRIMINOLOGY AND PUBLIC POLICY, Issue 3 2007PAUL J. HOFER Research Summary: In United States v. Booker, the U.S. Supreme Court held that the federal sentencing guidelines must be considered advisory, rather than mandatory, if they are to remain constitutional under the Sixth Amendment. Since the decision, the U.S. Sentencing Commission has provided policy makers with accurate and current data on changes and continuity in federal sentencing practices. Unlike previous changes in legal doctrine, Booker immediately increased the rates of upward and downward departures from the guideline range. Government-sponsored downward departures remain the leading category of outside,the-range sentences. The rate of within-range sentences, although lower than in the period immediately preceding Booker, remains near rates observed earlier in the guidelines era. Despite the increase in departures, average sentence lengths for the overall caseload remain stable, because of offsetting increases in the seriousness of the crimes being sentenced and in the severity of penalties for those crimes. Analyses of the reasons that judges reported for downward departures suggest that treatment of criminal history and offender characteristics are the two leading areas of dissatisfaction with the guidelines. Policy Implications: Assessment of changes in sentencing practices following Booker by different observers depends partly on competing institutional perspectives and on different degrees of trust in the judgment of judges, prosecutors, the Sentencing Commission, and Congress. No agreement on whether Booker has bettered or worsened the system can be achieved until agreement exists on priorities among the purposes of sentencing and the goals of sentencing reform. Both this lack of agreement and an absence of needed data make consensus on Booker's effects on important sentencing goals, such as reduction of unwarranted disparity, unlikely in the near future. Similarly, lack of baseline data before Booker on the effectiveness of federal sentencing at crime control makes before-after comparisons impossible. Despite these limitations, research provides a sounder framework for policy making than do anecdotes or speculation and sets valuable empirical parameters for the federal sentencing policy debate. [source] Laminin and fibronectin modulate inner ear spiral ganglion neurite outgrowth in an in vitro alternate choice assayDEVELOPMENTAL NEUROBIOLOGY, Issue 13 2007Amaretta R. Evans Abstract Extracellular matrix (ECM) molecules have been shown to function as cues for neurite guidance in various populations of neurons. Here we show that laminin (LN) and fibronectin (FN) presented in stripe micro-patterns can provide guidance cues to neonatal (P5) inner ear spiral ganglion (SG) neurites. The response to both ECM molecules was dose-dependent. In a LN versus poly- L -lysine (PLL) assay, neurites were more often observed on PLL at low coating concentrations (5 and 10 ,g/mL), while they were more often on LN at a high concentration (80 ,g/mL). In a FN versus PLL assay, neurites were more often on PLL than on FN stripes at high coating concentrations (40 and 80 ,g/mL). In a direct competition between LN and FN, neurites were observed on LN significantly more often than on FN at both 10 and 40 ,g/mL. The data suggest a preference by SG neurites for LN at high concentrations, as well as avoidance of both LN at low and FN at high concentrations. The results also support a potential model for neurite guidance in the developing inner ear in vivo. LN, in the SG and osseus spiral lamina may promote SG dendrite growth toward the organ of Corti. Within the organ of Corti, lower concentrations of LN may slow neurite growth, with FN beneath each row of hair cells providing a stop or avoidance signal. This could allow growth cone filopodia increased time to sample their cellular targets, or direct the fibers upward toward the hair cells. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007 [source] Effects of labedipinedilol-A, third-generation dihydropyridine-type calcium blocker, on ouabain-induced arrhythmiaDRUG DEVELOPMENT RESEARCH, Issue 1 2008Jhy-Chong Liang Abstract Labedipinedilol-A, a novel dihydropyridine-type calcium antagonist with ,/,-adrenoceptor blocking properties, has been reported to produce a cardioprotective effect against ischemia reperfusion injury in rats. We investigated the protective effects of labedipinedilol-A on ouabain-induced tonotropy and arrhythmias in isolated whole atria, and using patch-clamp techniques to study the underlying mechanism of its antiarrhythmic activity on isolated cardiac myocytes. Labedipinedilol-A (10,µM) suppressed the tonotropic effect of ouabain significantly and prolonged the onset time of extra-systole (arrhythmia) induced by ouabain in isolate atria. In the voltage-clamp study, labedipinedilol-A (1,100,µM) reduced the peak amplitude of sodium inward current (INa) and L-type calcium current (ICa-L), and shifted the current-voltage (I-V) curve upward in a concentration-dependent manner. In contrast, the addition of labedipinedilol-A increased transient outward potassium current (Ito) and inward rectifier potassium current (IK1) significantly. Labedipinedilol-A (10,µM) also effectively depressed the isoproterenol-induced increase in the Ca2+ current. These results show that labedipinedilol-A blocks ICa-L and INa, and increases Ito and IK1. These findings indicate that labedipinedilol-A produces direct cardiac action, probably due to the inhibition of cardiac Na+ and Ca2+ channels. Our results suggest that labedipinedilol-A may reduce the membrane conduction through inhibition of ionic channels which decrease ouabain-induced arrhythmia. Drug Dev Res 69:26,33, 2008 © 2008 Wiley-Liss, Inc. [source] The use of multivariate statistics to elucidate patterns of floodplain sedimentation at different spatial scalesEARTH SURFACE PROCESSES AND LANDFORMS, Issue 5 2007Martin C. Thoms Abstract Floodplains are depositional features of riverine landscapes that display complex sedimentation patterns that are amenable to multi-scale approaches. We examined sedimentation in the Lower Balonne floodplain, Queensland, Australia, at three different spatial scales: the channel (103 km), floodplain process zone (10 km) and geomorphic unit (102 m) scales, and compared scale-related patterns evident from stratigraphy with those evident from quantitative multivariate analysis. Three stratigraphic sequences were found in the Lower Balonne floodplain: generally fining upward, episodic fining upward, and mud-dominated. Stratigraphical analysis revealed the detailed character of sedimentary sequences embedded within the scale patterns derived from multivariate analysis. Multivariate statistical analyses of a range of textural and geochemical data revealed different patterns of floodplain sedimentation at each scale. At the channel scale, sediment texture and geochemistry were more heterogeneous in the Culgoa River than in Briarie Creek. At the floodplain process zone scale clear patterns of sediment texture and geochemistry were observed along the upper, mid and lower floodplain process zones of Briarie Creek, but not along the Culgoa River. At the geomorphic unit scale, clear patterns of sediment texture and geochemistry were observed among the bank, buried channel and flat floodplain units of the Culgoa River, but were not as clear in Briarie Creek. Recognition of rivers as hierarchically organized systems is an emerging paradigm in river science. Our study supports this paradigm by demonstrating that different sedimentation patterns occur at different scales to reveal a hierarchically organized floodplain environment. Copyright © 2006 John Wiley & Sons, Ltd. [source] Spatial and temporal variations of two cyprinids in a subtropical mountain reserve , a result of habitat disturbanceECOLOGY OF FRESHWATER FISH, Issue 3 2007C.-C. Han Abstract,,, We investigated the variations of population of two cyprinids, Varicorhinus alticorpus and Varicorhinus barbatulus, using long-term survey data (1995,2004) in the subtropical island of Taiwan. Fish abundance data showed that at the mainstem stations, V. barbatulus which used to dominate in the higher altitude had declined significantly, while V. alticorpus that used to occupy only the lower altitude had spread upward. However, at the tributaries, trend of the populations of V. barbatulus were not significantly different over time, while populations of V. alticorpus were absent at higher altitude but began to increase at lower altitude. Environmental parameters revealed that sporadic high turbidity was observed at the mainstem stations, but not at the tributaries. Images taken before and after typhoon also showed habitat destruction by debris flow at the mainstem stations. As some models predicted that suitable fish habitats will shrink because of increasing water temperature due to global warming, we showed that fish distribution may be affected by habitat disturbance due to intensified storms sooner than the actual increase of water temperature. [source] Large-scale distribution and activity patterns of an extremely low-light-adapted population of green sulfur bacteria in the Black SeaENVIRONMENTAL MICROBIOLOGY, Issue 5 2010Evelyn Marschall Summary The Black Sea chemocline represents the largest extant habitat of anoxygenic phototrophic bacteria and harbours a monospecific population of Chlorobium phylotype BS-1. High-sensitivity measurements of underwater irradiance and sulfide revealed that the optical properties of the overlying water column were similar across the Black Sea basin, whereas the vertical profiles of sulfide varied strongly between sampling sites and caused a dome-shaped three-dimensional distribution of the green sulfur bacteria. In the centres of the western and eastern basins the population of BS-1 reached upward to depths of 80 and 95 m, respectively, but were detected only at 145 m depth close to the shelf. Using highly concentrated chemocline samples from the centres of the western and eastern basins, the cells were found to be capable of anoxygenic photosynthesis under in situ light conditions and exhibited a photosynthesis,irradiance curve similar to low-light-adapted laboratory cultures of Chlorobium BS-1. Application of a highly specific RT-qPCR method which targets the internal transcribed spacer (ITS) region of the rrn operon of BS-1 demonstrated that only cells at the central station are physiologically active in contrast to those at the Black Sea periphery. Based on the detection of ITS-DNA sequences in the flocculent surface layer of deep-sea sediments across the Black Sea, the population of BS-1 has occupied the major part of the basin for the last decade. The continued presence of intact but non-growing BS-1 cells at the periphery of the Black Sea indicates that the cells can survive long-distant transport and exhibit unusually low maintenance energy requirements. According to laboratory measurements, Chlorobium BS-1 has a maintenance energy requirement of ,1.6,4.9·10,15 kJ cell,1 day,1 which is the lowest value determined for any bacterial culture so far. Chlorobium BS-1 thus is particularly well adapted to survival under the extreme low-light conditions of the Black Sea, and can be used as a laboratory model to elucidate general cellular mechanisms of long-term starvation survival. Because of its adaptation to extreme low-light marine environments, Chlorobium BS-1 also represents a suitable indicator for palaeoceanography studies of deep photic zone anoxia in ancient oceans. [source] Effects of Predation Risk on Vertical Habitat Use and Foraging of Pardosa milvinaETHOLOGY, Issue 12 2006Hillary C. Folz Animals face the risk of predation while engaging in regular activities, such as foraging, mate-seeking, and reproducing. In order to avoid predation, prey can modify behavior to prevent capture. Pardosa milvina may climb in response to chemotactile cues of Hogna helluo, a larger cooccurring wolf spider, to avoid predation. The purpose of this study was to test the effects of the location of predator cues on the climbing response of P. milvina and to test how this antipredator behavior affected foraging success. In experimental arenas, when cues were on the bottom of the containers, P. milvina moved upward, and when cues were on the walls, individuals moved downward. These results suggest that P. milvina respond to H. helluo cues with general avoidance and do not automatically climb in response to the cues. As H. helluo spend most of their time on the ground, P. milvina may avoid predation by spending more time climbing in areas with H. helluo cues. The presence of predator cues significantly decreased foraging by P. milvina. But within the predator cue treatments, climbing ability had no effect on foraging, possibly due to the short height of the feeding arenas. Future studies are needed to determine if climbing by P. milvina in response to cues of H. helluo has direct and indirect negative effects on herbivores in the field. [source] Levodopa-induced ocular dyskinesia in Parkinson's diseaseEUROPEAN JOURNAL OF NEUROLOGY, Issue 10 2007H. Grötzsch Levodopa (LD)-induced dyskinesia (LID), one of the most common motor complications in advanced Parkinson's disease (PD), involve mostly the limbs, trunk and head, but unusual locations have been reported including respiratory muscles, the face and the eyes. The aim of this study was to further investigate the frequency and characteristics of LD-related abnormal involuntary eye movements (AIEMs) in PD. Thirty-two patients with advanced PD and various motor complications were evaluated and videotaped in an ON and OFF state. We found AIEMs in five patients (16%) which were present exclusively during the ON state and which completely disappeared when OFF. They consisted of repeated, stereotyped upward and/or sideways gaze deviation movements, sometimes phasic, brief and jerky, sometimes tonic and sustained for several seconds. The main direction of gaze deviation was toward the side more affected by parkinsonism. AIEMs typically paralleled limb and trunk LID and were modulated by the same facilitation and inhibitory maneuvers. We concluded that AIEMs are not uncommon in advanced PD and represent a particular topography of LID, hence the term ,ocular dyskinesia' to designate these AIEMs that seem to have a specific pattern in PD as compared with other forms of parkinsonism. [source] Choice of comparisons in intergroup settings: the role of temporal information and comparison motivesEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 5 2006Rupert J. Brown Three studies investigated comparison choices in intergroup settings, a neglected but important topic for theories of intergroup relations. Two main questions were addressed: What is role of comparison motives in determining comparison choices in intergroup contexts? How important are temporal comparisons (of the ingroup in the past or future) in intergroup settings? In Study 1 (N,=,115), motives for Assessment or Enhancement were primed in a multi-group performance context. Compared to Controls, Assessment priming encouraged both upward and downward comparisons, while Enhancement encouraged mainly downward comparisons. In general, temporal comparisons were as prevalent as comparisons with other groups. Study 2 (N,=,199) employed a real-world setting in which members of a mid-ranking university indicated their interest in comparing with other higher or lower status universities or with their own university in the past. Temporal comparisons were once more much in evidence, and manipulating enhancement motives again encouraged downward comparisons. In Study 3 (N,=,40), set in the context of inter-nation student comparisons, Improvement motives were primed implicitly. This led to an increase in interest in an outgroup just above the ingroup but to a decrease in interest in future-oriented comparisons. Copyright © 2006 John Wiley & Sons, Ltd. [source] The affective consequences of social comparison as related to professional burnout and social comparison orientationEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 4 2001Bram P. Buunk In a study among sociotherapists, the affective consequences of social comparison were examined and related to professional burnout and to individual differences in social comparison orientation. Participants were confronted with a bogus interview with an upward versus a downward comparison target. Upward comparison generated more positive and less negative affect than did downward comparison. Increasing levels of burnout were accompanied by less positive affect in response to upward comparison. Moreover, the higher the level of burnout, the more negative affect a description of a downward comparison target evoked, but only among individuals high in social comparison orientation. Finally, the higher the level of burnout, the higher the identification with the downward target, and the lower the identification with the upward target. However, this last effect did occur only among those low in social comparison orientation. Those high in social comparison orientation kept identifying with the upward target, even when they were high in burnout. Copyright © 2001 John Wiley & Sons, Ltd. [source] POWER AND POTENTIAL BIAS IN FIELD STUDIES OF NATURAL SELECTIONEVOLUTION, Issue 3 2004Erika I. Hersch Abstract The advent of multiple regression analyses of natural selection has facilitated estimates of both the direct and indirect effects of selection on many traits in numerous organisms. However, low power in selection studies has possibly led to a bias in our assessment of the levels of selection shaping natural populations. Using calculations and simulations based on the statistical properties of selection coefficients, we find that power to detect total selection (the selection differential) depends on sample size and the strength of selection relative to the opportunity of selection. The power of detecting direct selection (selection gradients) is more complicated and depends on the relationship between the correlation of each trait and fitness and the pattern of correlation among traits. In a review of 298 previously published selection differentials, we find that most studies have had insufficient power to detect reported levels of selection acting on traits and that, in general, the power of detecting weak levels of selection is low given current study designs. We also find that potential publication bias could explain the trend that reported levels of direct selection tend to decrease as study sizes increase, suggesting that current views of the strength of selection may be inaccurate and biased upward. We suggest that studies should be designed so that selection is analyzed on at least several hundred individuals, the total opportunity of selection be considered along with the pattern of selection on individual traits, and nonsignificant results be actively reported combined with an estimate of power. [source] CALIBRATING A MOLECULAR CLOCK FROM PHYLOGEOGRAPHIC DATA: MOMENTS AND LIKELIHOOD ESTIMATORSEVOLUTION, Issue 10 2003Michael J. Hickerson Abstract We present moments and likelihood methods that estimate a DNA substitution rate from a group of closely related sister species pairs separated at an assumed time, and we test these methods with simulations. The methods also estimate ancestral population size and can test whether there is a significant difference among the ancestral population sizes of the sister species pairs. Estimates presented in the literature often ignore the ancestral coalescent prior to speciation and therefore should be biased upward. The simulations show that both methods yield accurate estimates given sample sizes of five or more species pairs and that better likelihood estimates are obtained if there is no significant difference among ancestral population sizes. The model presented here indicates that the larger than expected variation found in multitaxa datasets can be explained by variation in the ancestral coalescence and the Poisson mutation process. In this context, observed variation can often be accounted for by variation in ancestral population sizes rather than invoking variation in other parameters, such as divergence time or mutation rate. The methods are applied to data from two groups of species pairs (sea urchins and Alpheus snapping shrimp) that are thought to have separated by the rise of Panama three million years ago. [source] Flaking failure originating from a single surface crack in silicon nitride under rolling contact fatigueFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 12 2005K. KIDA ABSTRACT Flaking failure caused by surface cracks of silicon nitride ceramic bearings has been investigated from the viewpoint of the ring crack model. However, the relation between surface and subsurface cracks under rolling contact fatigue is not fully understood. In this investigation subsurface cracks branching from an initial surface crack were observed in detail, and the process of flaking failure was investigated. The specimens were observed prior to the separation of the surface layers and it was found that the initial surface cracks grew vertically to the surfaces and did not curve as predicted by the ring crack model. Subsurface cracks branched from the single surface cracks and grew in a direction parallel to the surface. They grew in both the same and the opposite directions to the ball movement, with small upward and downward branches. These subsurface cracks grew prior to the semi-circular surface cracks. From these observations it was concluded that the flaking failures are not caused directly by the surface cracks, but by the subsurface cracks that branch from them. [source] Implication of the glutamine synthetase/glutamate synthase pathway in conditioning the amino acid metabolism in bundle sheath and mesophyll cells of maize leavesFEBS JOURNAL, Issue 12 2008Marie-Hélène Valadier We investigated the role of glutamine synthetases (cytosolic GS1 and chloroplast GS2) and glutamate synthases (ferredoxin-GOGAT and NADH-GOGAT) in the inorganic nitrogen assimilation and reassimilation into amino acids between bundle sheath cells and mesophyll cells for the remobilization of amino acids during the early phase of grain filling in Zea mays L. The plants responded to a light/dark cycle at the level of nitrate, ammonium and amino acids in the second leaf, upward from the primary ear, which acted as the source organ. The assimilation of ammonium issued from distinct pathways and amino acid synthesis were evaluated from the diurnal rhythms of the transcripts and the encoded enzyme activities of nitrate reductase, nitrite reductase, GS1, GS2, ferredoxin-GOGAT, NADH-GOGAT, NADH-glutamate dehydrogenase and asparagine synthetase. We discerned the specific role of the isoproteins of ferredoxin and ferredoxin:NADP+ oxidoreductase in providing ferredoxin-GOGAT with photoreduced or enzymatically reduced ferredoxin as the electron donor. The spatial distribution of ferredoxin-GOGAT supported its role in the nitrogen (re)assimilation and reallocation in bundle sheath cells and mesophyll cells of the source leaf. The diurnal nitrogen recycling within the plants took place via the specific amino acids in the phloem and xylem exudates. Taken together, we conclude that the GS1/ferredoxin-GOGAT cycle is the main pathway of inorganic nitrogen assimilation and recycling into glutamine and glutamate, and preconditions amino acid interconversion and remobilization. [source] Optimal designs for estimating penetrance of rare mutations of a disease-susceptibility geneGENETIC EPIDEMIOLOGY, Issue 3 2003Gail Gong Abstract Many clinical decisions require accurate estimates of disease risks associated with mutations of known disease-susceptibility genes. Such risk estimation is difficult when the mutations are rare. We used computer simulations to compare the performance of estimates obtained from two types of designs based on family data. In the first (clinic-based designs), families are ascertained because they meet certain criteria concerning multiple disease occurrences among family members. In the second (population-based designs), families are sampled through a population-based registry of affected individuals called probands, with oversampling of probands whose families are more likely to segregate mutations. We generated family structures, genotypes, and phenotypes using models that reflect the frequencies and penetrances of mutations of the BRCA1/2 genes. We studied the effects of risk heterogeneity due to unmeasured, shared risk factors by including risk variation due to unmeasured genotypes of another gene. The simulations were chosen to mimic the ascertainment and selection processes commonly used in the two types of designs. We found that penetrance estimates from both designs are nearly unbiased in the absence of unmeasured shared risk factors, but are biased upward in the presence of such factors. The bias increases with increasing variation in risks across genotypes of the second gene. However, it is small compared to the standard error of the estimates. Standard errors from population-based designs are roughly twice those from clinic-based designs with the same number of families. Using the root-mean-square error as a measure of performance, we found that in all instances, the clinic-based designs gave more accurate estimates than did the population-based designs with the same numbers of families. Rough variance calculations suggest that clinic-based designs give more accurate estimates because they include more identified mutation carriers. Genet Epidemiol 24:173,180, 2003. © 2003 Wiley-Liss, Inc. [source] Beyond stratigraphic noise: Unraveling the evolution of stratified assemblages in faunalturbated sitesGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 6 2006Eugène Morin This study explores the stratigraphic evolution of archaeological assemblages in faunalturbated sites. These sites are sometimes described as having limited archaeological value because of varying degrees of occupation mixing. It is argued here that the vertical distribution of assemblages is predictable in faunalturbated contexts. Understanding this vertical evolution may lead to a better assessment of the archaeological potential of a cultural sequence. In faunalturbated soils, the stratigraphic evolution of the assemblages is largely dictated by faunal activity. Tunneling by small animals tend to "sink" cultural remains through the deposits. Although objects sink at a relatively fast pace near the surface, the process slows down as the objects reach the bottom of the biomantle where the sediments are more compact. This process affects the shape of the artifact vertical distribution. The analysis of a multicomponent site from southern Québec is used to model how assemblages may evolve temporally in faunalturbated settings. At Station 3-avant, the stratigraphic distribution of the cultural remains appears to evolve from an upward-skewed distribution to a bottom-skewed distribution through time. This evolution is interpreted to result from the fact that objects are often too large and/or heavy to be moved upward by the pedofauna. In situations in which this stage of stratigraphic evolution is not yet reached, enough information about temporal successions may be retained for the site to be useful for investigating diachronic change. This may prove invaluable in regions in which faunalturbated sequences are common. © 2006 Wiley Periodicals, Inc. [source] Triassic metasedimentary successions across the boundary between the southern Apennines and the Calabrian Arc (northern Calabria, Italy)GEOLOGICAL JOURNAL, Issue 2 2005A. Iannace Abstract The boundary area between the Apenninic fold-and-thrust belt and the crystalline Calabrian Arc, located around Sangineto in northern Calabria, has been investigated. New geological mapping in the Sant'Agata area has been performed on the Triassic successions traditionally attributed to the metasedimentary San Donato Unit. This, coupled with a reappraisal of the stratigraphy and tectonics of coeval successions present more to the south in the Cetraro Unit, results in a new reconstruction of the Triassic evolution of all the metasedimentary successions found in the region. Four informal stratigraphic units have been distinguished in the S. Agata area. The lowest one (Unit A) consists of well-bedded metalimestones and bioturbated marly limestones that correlate with Ladinian,Carnian carbonates in nearby areas. A second unit (Unit B), never recognized before, contains a complex alternation of dolomites, phyllites and some meta-arenites containing several beds of Cavernoso facies, attributed to the Carnian. They grade upward to platform and platform-margin dolomites of Norian,Rhaetian age (Unit C) that in turn are replaced upward and laterally by a fourth unit (Unit D) consisting of well-bedded, dark dolomites and metalimestones with marly interlayers locally found as resedimented large blocks in slope conglomerates. Unit D correlates with Rhaetian,Liassic beds in nearby areas. Several pieces of evidence of post-metamorphic contractional tectonics, with 140°N and 30°N trends, are found together with evidence of SW-directed extension. The siliciclastic Carnian beds of Unit B are correlated with the phyllites of Cetraro, formerly believed to be Middle Triassic; moreover, it is suggested that in the Cetraro area Unit C is almost totally replaced by Unit D. This demonstrates that the former distinction between the two tectonic units in the whole area has to be discarded. We have made a general palaeoenvironmental reconstruction which progresses laterally, during Ladinian,Carnian times, from (i) a coastal, mixed siliciclastic,carbonate,evaporitic area at Cetraro to (ii) a transitional carbonate shelf where siliciclastic input was only episodic, and finally to (iii) a bioconstructed margin which was later replaced by a steepened margin created by tectonic instability. Starting from the Norian, subsidence shifted toward the former coastal area where an intraplatform, restricted basin developed. The proposed stratigraphy corresponds closely to the Alpujarride units of the Betic Cordillera, Spain. Moreover, it is shown that strong affinities also exist, in terms of the structural framework, with the metamorphic units of Tuscany and Liguria. Copyright © 2005 John Wiley & Sons, Ltd. [source] Gravity evidence for a larger Limpopo Belt in southern Africa and geodynamic implicationsGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2002R. T. Ranganai Summary The Limpopo Belt of southern Africa is a Neoarchean orogenic belt located between two older Archean provinces, the Zimbabwe craton to the north and the Kaapvaal craton to the south. Previous studies considered the Limpopo Belt to be a linearly trending east-northeast belt with a width of ,250 km and ,600 km long. We provide evidence from gravity data constrained by seismic and geochronologic data suggesting that the Limpopo Belt is much larger than previously assumed and includes the Shashe Belt in Botswana, thus defining a southward convex orogenic arc sandwiched between the two cratons. The 2 Ga Magondi orogenic belt truncates the Limpopo,Shahse Belt to the west. The northern marginal, central and southern marginal tectonic zones define a single gravity anomaly on upward continued maps, indicating that they had the same exhumation history. This interpretation requires a tectonic model involving convergence between the Kaapvaal and Zimbabwe cratons during a Neoarchean orogeny that preserved the thick cratonic keel that has been imaged in tomographic models. [source] Airborne gravity tests in the Italian area to improve the geoid model of ItalyGEOPHYSICAL PROSPECTING, Issue 4 2009R. Barzaghi ABSTRACT Airborne gravimetry is an important method for measuring gravity over large unsurveyed areas. This technology has been widely applied in Canada, Antarctica and Greenland to map the gravity fields of these regions and in recent years, in the oil industry. In 2005, two tests in the Italian area were performed by ENI in cooperation with the Politecnico di Milano and the Danish National Space Center. To the knowledge of the authors, these were the first experiments of this kind in Italy and were performed over the Ionian coasts of Calabria and the Maiella Mountains. The Calabria test field is characterized by strong gravity variations due to the geophysical and topographic structure of the area. The ground gravity coverage is also quite dense. It was thus possible to compare airborne gravity with the ground observed values in order to check the precision of the airborne gravimetry. The second campaign was performed in an unsurveyed area centred on the Maiella Mountains, thus filling the data gap of this zone. Comparisons with existing ground data were also carried out in this area. After smoothing, the collected data have an accuracy of 2,3 mgal, as derived by cross-over analysis. Moreover, the collocation method applied to compare and merge ground-based and airborne data proved to be efficient and reliable. The standard deviation of the discrepancies between airborne data and collocation upward continued gravity is, in both cases, less than 8 mgal. In the Maiella test, the gravity field obtained by merging airborne and ground data using collocation also provides a more detailed description of the high-frequency pattern of the geopotential field in this area. [source] Late-glacial and Holocene vegetation, climate and fire dynamics in the Serra dos Órgãos, Rio de Janeiro State, southeastern BrazilGLOBAL CHANGE BIOLOGY, Issue 6 2010HERMANN BEHLING Abstract We present a high-resolution pollen and charcoal record of a 218 cm long sediment core from the Serra dos Órgãos, a subrange of the coastal Serra do Mar, located at 2130 m altitude in campos de altitude (high elevation grass- and shrubland) vegetation near Rio de Janeiro in southeastern Brazil to reconstruct past vegetation, climate and fire dynamics. Based on seven AMS 14C ages, the record represents at least the last 10 450 14C yr bp (12 380 cal years bp), The uppermost region was naturally covered by campos de altitude throughout the recorded period. Diverse montane Atlantic rain forest (ARF) occurred close to the studied peat bog at the end of the Late-glacial period. There is evidence of small Araucaria angustifolia populations in the study area as late as the early Holocene, after which point the species apparently became locally extinct. Between 10 380 and 10 170 14C yr bp (12 310,11 810 cal yr bp), the extent of campos de altitude was markedly reduced as montane ARF shifted rapidly upward to higher elevations, reflecting a very wet and warm period (temperatures similar to or warmer than present day) at the end of the Younger Dryas (YD) chronozone. This is in opposition to the broadly documented YD cooling in the northern Hemisphere. Reduced cross-equatorial heat transport and movement of the Intertropical Convergence Zone over northeastern Brazil may explain the YD warming. Markedly extended campos de altitude vegetation indicates dry climatic conditions until about 4910 14C yr bp (5640 cal yr bp). Later, wetter conditions are indicated by reduced high elevation grassland and the extension of ARF into higher elevation. Fire frequency was high during the early Holocene but decreased markedly after about 7020 14C yr bp (7850 cal yr bp). [source] Is the Sonoran Desert losing its cool?GLOBAL CHANGE BIOLOGY, Issue 12 2005Jeremy L. Weiss Abstract Freezing temperatures strongly influence vegetation in the hottest desert of North America, in part determining both its overall boundary and distributions of plant species within. To evaluate recent variability of freezing temperatures in this context, minimum temperature data from weather stations in the Sonoran Desert are examined. Data show widespread warming trends in winter and spring, decreased frequency of freezing temperatures, lengthening of the freeze-free season, and increased minimum temperatures per winter year. Local land use and multidecadal modes of the global climate system such as the Pacific decadal oscillation and the Atlantic multidecadal oscillation do not appear to be principal drivers of this warming. Minimum temperature variability in the Sonoran Desert does, however, correspond to global temperature variability attributed to human-dominated global warming. With warming expected to continue at faster rates throughout the 21st century, potential ecological responses may include contraction of the overall boundary of the Sonoran Desert in the south-east and expansion northward, eastward, and upward in elevation, as well as changes to distributions of plant species within and other characteristics of Sonoran Desert ecosystems. Potential trajectories of vegetation change in the Sonoran Desert region may be affected or made more difficult to predict by uncertain changes in warm season precipitation variability and fire. Opportunities now exist to investigate ecosystem response to regional climate disturbance, as well as to anticipate and plan for continued warming in the Sonoran Desert region. [source] Impact of land use and land cover change on groundwater recharge and quality in the southwestern USGLOBAL CHANGE BIOLOGY, Issue 10 2005Bridget R. Scanlon Abstract Humans have exerted large-scale changes on the terrestrial biosphere, primarily through agriculture; however, the impacts of such changes on the hydrologic cycle are poorly understood. The purpose of this study was to test the hypothesis that the conversion of natural rangeland ecosystems to agricultural ecosystems impacts the subsurface portion of the hydrologic cycle by changing groundwater recharge and flushing salts to underlying aquifers. The hypothesis was examined through point and areal studies investigating the effects of land use/land cover (LU/LC) changes on groundwater recharge and solute transport in the Amargosa Desert (AD) in Nevada and in the High Plains (HP) in Texas, US. Studies use the fact that matric (pore-water-pressure) potential and environmental-tracer profiles in thick unsaturated zones archive past changes in recharging fluxes. Results show that recharge is related to LU/LC as follows: discharge through evapotranspiration (i.e., no recharge; upward fluxes <0.1 mm yr,1) in natural rangeland ecosystems (low matric potentials; high chloride and nitrate concentrations); moderate-to-high recharge in irrigated agricultural ecosystems (high matric potentials; low-to-moderate chloride and nitrate concentrations) (AD recharge: ,130,640 mm yr,1); and moderate recharge in nonirrigated (dryland) agricultural ecosystems (high matric potentials; low chloride and nitrate concentrations, and increasing groundwater levels) (HP recharge: ,9,32 mm yr,1). Replacement of rangeland with agriculture changed flow directions from upward (discharge) to downward (recharge). Recent replacement of rangeland with irrigated ecosystems was documented through downward displacement of chloride and nitrate fronts. Thick unsaturated zones contain a reservoir of salts that are readily mobilized under increased recharge related to LU/LC changes, potentially degrading groundwater quality. Sustainable land use requires quantitative knowledge of the linkages between ecosystem change, recharge, and groundwater quality. [source] Extremely Alkaline (pH > 12) Ground Water Hosts Diverse Microbial CommunityGROUND WATER, Issue 4 2006George S. Roadcap Chemically unusual ground water can provide an environment for novel communities of bacteria to develop. Here, we describe a diverse microbial community that inhabits extremely alkaline (pH > 12) ground water from the Lake Calumet area of Chicago, Illinois, where historic dumping of steel slag has filled in a wetland. Using microbial 16S ribosomal ribonucleic acid gene sequencing and microcosm experiments, we confirmed the presence and growth of a variety of alkaliphilic ,-Proteobacteria, Bacillus, and Clostridium species at pH up to 13.2. Many of the bacterial sequences most closely matched those of other alkaliphiles found in more moderately alkaline water around the world. Oxidation of dihydrogen produced by reaction of water with steel slag is likely a primary energy source to the community. The widespread occurrence of iron-oxidizing bacteria suggests that reduced iron serves as an additional energy source. These results extend upward the known range of pH tolerance for a microbial community by as much as 2 pH units. The community may provide a source of novel microbes and enzymes that can be exploited under alkaline conditions. [source] Time to include time to death?HEALTH ECONOMICS, Issue 4 2004The future of health care expenditure predictions Abstract Government projections of future health care expenditures , a great concern given the aging baby-boom generation , are based on econometric regressions that control explicitly for age but do not control for end-of-life expenditures. Because expenditures increase dramatically on average at the end of life, predictions of future cost distributions based on regressions that omit time to death as an explanatory variable will be biased upward (or, more explicitly, the coefficients on age will be biased upward) if technology or other social factors continue to prolong life. Although health care expenditure predictions for a current sample will not be biased, predictions for future cohorts with greater longevity will be biased upwards, and the magnitude of the bias will increase as the expected longevity increases. We explore the empirical implications of incorporating time to death in longitudinal models of health expenditures for the purpose of predicting future expenditures. Predictions from a simple model that excludes time to death and uses current life tables are 9% higher than from an expanded model controlling for time to death. The bias increases to 15% when using projected life tables for 2020. The predicted differences between the models are sufficient to justify reassessment of the value of inclusion of time to death in models for predicting health care expenditures. Copyright © 2003 John Wiley & Sons, Ltd. [source] Experimental study of the flow boiling heat transfer enhancement and pressure drop due to the bubble behavior restricted by a screen sheetHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 4 2003Katsuhiko Kadoguchi Abstract A unique method previously proposed by the authors was applied to the heat transfer augmentation in the flow boiling field. In this method a screen sheet was placed on the horizontal heated surface where bubble nucleation occurred. Generated vapor bubbles were trapped between the screen and the wall, became flat, and moved along the surface. This restricted bubble behavior caused the heat transfer enhancement. Three types of screen sheet were tested in the present experiment and the effect of the screen on the heat transfer and two-phase flow characteristics was investigated. In two of these cases, the screen was displaced upward by the bubble nucleation. Compared with the ordinary flow boiling case, heat transfer was enhanced by a factor of 1.2 to 6 within the present experimental range. Using a simple flow model, it was made clear that the effect of the height of the displaced screen was important in evaluating the increase in pressure drop. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(4): 319,329, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10094 [source] Medial septal modulation of the ascending brainstem hippocampal synchronizing pathways in the anesthetized ratHIPPOCAMPUS, Issue 1 2006Jesse Jackson Abstract Independent and combined electrical stimulation pairings of the medial septum (MS), posterior hypothalamus (PH), and reticular pontine oralis (RPO) of the brainstem were performed in the acute urethane anesthetized rat, while recording field activity from electrodes in either the stratum oriens or stratum moleculare of the hippocampal formation. Theta frequency and power were measured during independent stimulation of each nuclei and during combined stimulation using three pairings: (1) MS,PH (2) MS,RPO and (3) PH,RPO. Each pairing consisted of parameters known to elicit theta of a high frequency for one nucleus, and parameters known to elicit a low frequency for the second nucleus. This methodology allowed us to observe whether one nucleus preferentially modulated theta activity in the hippocampus in terms of frequency and power. The MS was observed to reset theta frequency in both the upward and downward direction when stimulated in combination with either the PH (Experiment 1) or the RPO (Experiment 2). In Experiment 3 (PH,RPO), the structure receiving the higher intensity stimulation had the predominate effect on theta frequency. With MS stimulation combinations, the power of the elicited theta activity was found to increase over the independent stimulation in some cases during Experiment 1. Likewise, in Experiment 2, the combined stimulation produced a power that in most cases was significantly greater than that measured during the independent stimulations. This effect was not observed with PH and RPO stimulation combinations. The combined stimulation of the PH and RPO yielded a power similar to the independent PH stimulations. The findings support the following conclusions: (1) the major theta generating activity of the ascending brainstem synchronizing pathways involves projections from the RPO to the PH, relayed through the MS, to the hippocampal formation; and (2) that the MS directly controls theta amplitude and secondarily translates the level of ascending brainstem activity into the appropriate frequency of hippocampal theta. © 2005 Wiley-Liss, Inc. [source] Medial septal modulation of the ascending brainstem hippocampal synchronizing pathways in the freely moving ratHIPPOCAMPUS, Issue 1 2006Brian H. Bland Abstract Rats implanted with hippocampal recording electrodes were tested in a wheel-running apparatus under three conditions: (1) independent electrical stimulation of the medial septal nucleus (MS); (2) independent electrical stimulation of the posterior hypothalamic nucleus (PH); and (3) combined electrical stimulation of the MS and PH using pairings of two stimulation conditions, 7 or10 Hz stimulation of the MS, and a low- or high-intensity PH stimulation. Quantitative measures of running speed were taken, and hippocampal recordings were subjected to fast-Fourier transform analysis. Electrical stimulation of the PH induced wheel-running behavior; running speed and the accompanying hippocampus (HPC) theta frequency increased with increase in stimulation intensity. Electrical stimulation of the MS failed to induce wheel-running behavior despite the fact that HPC theta was induced at the frequency of the applied stimulation (7 and 10 Hz). Electrical stimulation of the MS reset the frequency of HPC theta induced by PH stimulation in both the upward and downward directions and increased theta power, while wheel-running speed was modulated in a downward direction only. © 2005 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||||||||||||||