56 research outputs found

    A Temporal GIS Approach to Characterizing Geographical Dynamics

    Get PDF
    Temporal GIS research has historically focused on change, motion, and events. This research introduces a framework to represent concepts of fluid kinematics with the emphasis on the concept of flows. General circulation models (GCMs) and other spatially explicit environmental models produce massive time series of geographic fields (e.g. temperature) that call for effective GIS approaches to elicit temporal information embedded in these model outputs. Common temporal GIS approaches with discrete constructs in space and time tend to overlook the spatiotemporal continuity that is fundamental to the understanding of geographic dynamic fields, such as temperature. Common methods of analyzing climatological characteristics center on trend analysis at fixed locations or monitoring meteorological phenomena, such as storm tracks, to evaluate circulation changes. The proposed temporal GIS framework, on the other hand, uses the velocity of virtual particles with fixed climatological values to capture changes in scalar continuous fields. The resulting spatiotemporal distributions of velocity suggest kinematic flows that can be used to recognize features indicative of geographic processes, such as divergence and convergence of isolines. Summative characterizations of these kinematic features highlight the embedded change and motion in these temporal sets of scalar fields and facilitate understanding and comparing model outputs

    Montmorency tart cherry supplementation and exercise positively affect bone microarchitecture and biomechanics in the growing skeleton

    Get PDF
    Objectives: This study investigated the efficacy of Montmorency tart cherry (TC) alone and in combination with exercise on improving bone quality in young growing animals and the underlying mechanisms of action.Methods: Six-week-old female C57BL/6 mice were randomly assigned to 4 groups (n=12 mice/group) in a 2x2 factorial design: control AIN-93G diet (CON), CON+exercise, TC (10% w/w), or TC+exercise. The exercise consisted of treadmill running for 30 min, 5 d/wk at 12 m/min and a 5 degree incline. Body weights were recorded weekly. After 8 wks of treatment, mesenchymal stem cells (MSC) in the tibial bone marrow were quantified via flow cytometry fluorescent activated cell sorting (FACS). Trabecular and cortical bone microarchitecture in the femur and lumbar vertebrae was assessed using micro-computed tomography. Biomechanical testing was performed using finite element analysis (FEA). The relative abundance of RNA for genes involved in osteoblast and osteoclast differentiation and activity was determined using RT-PCR. Data were analyzed using a 2-way ANOVA with TC and exercise as factors.Results: At the end of the study, no differences in body weight were observed. Trabecular bone volume in the femur and spine was increased with exercise and TC (p<0.05), but there was no interaction. Cortical bone thickness in the vertebra was also increased by TC and exercise (p<0.001), but not in the femur. Trabecular bone strength and stiffness were increased in the vertebra in response to TC and exercise, but only in response to TC in the femur (P<0.001). An increase in bone marrow MSCs occurred in response to exercise (p<0.01), but not TC. However, the combination of TC and exercise reduced nuclear factor of activated T-cells 1 (Nfatc1) femur gene expression, a key regulator of osteoclastogenesis (p<0.05). TC also increased bone morphogenetic protein (BMP)2 gene expression, a regulator of osteoblastogenesis.Conclusion: Our data indicate that TC and exercise alone had positive effects on bone quality by suppressing regulators of osteoclastogenesis and increasing regulators of osteoblastogenesis. Even though the effects of TC and exercise were not synergistic, the effects of TC alone on bone were similar to and in some cases greater than exercise alone

    The Usefulness of Elemental Iron for Cereal Flour Fortification: a Sustain Task Force Report

    Get PDF
    Fortification of cereal flours may be a useful public health strategy to combat iron deficiency. Cereal flours that are used shortly after production (e.g., baking flour) can be fortified with soluble iron compounds, such as ferrous sulfate, whereas the majority of flours stored for longer periods is usually fortified with elemental iron powders to avoid unacceptable sensory changes. Elemental iron powders are less well absorbed than soluble iron compounds and they vary widely in their absorption depending on manufacturing method and physicochemical characteristics. Costs vary with powder type, but elemental iron powders are generally less expensive than ferrous sulfate. This review evaluates the usefulness of the different elemental iron powders based on results from in vitro studies, rat assays, human bioavailability studies, and efficacy studies monitoring iron status in human subjects. It concludes that, at the present time, only electrolytic iron powder can be recommended as an iron fortificant. Because it is only approximately half as well absorbed as ferrous sulfate, it should be added to provide double the amount of iro

    Female Adolescent Soccer Players Utilize Different Neuromuscular Strategies Between Limbs During the Propulsion Phase of a Lateral Vertical Jump

    Get PDF
    # Background Multiplanar dynamic stability is an important unilateral function in soccer performance but has been scarcely examined in female soccer players. The lateral vertical jump task assesses unilateral functional performance, and energy generation contribution examines how each joint (hip, knee, ankle) contributes to the vertical component of the vertical jump phase to measure inter- and intra-limb differences. # Purpose To examine dominant versus non-dominant limb performance using energy generation contribution of the hip, knee, and ankle during the vertical jump component of the lateral vertical jump. # Study Design Cross-sectional observational study. # Methods Seventeen healthy, adolescent female soccer players (age 13.4±1.7 years; height 160.6±6.0 cm; mass 53.1±8.2 kg) participated. Quadriceps strength was measured via isokinetic dynamometry. Energy generation contribution (measured from maximal knee flexion to toe off) and vertical jump height were measured during the vertical component of the lateral vertical jump. # Results There was no significant difference between limbs for quadriceps strength (p=0.64), jump height (p=0.59), or ankle energy generation contribution (p=0.38). Energy generation contribution was significantly greater in the dominant hip (dominant 29.7±8.6%, non-dominant 18.4±6.3%, p\<0.001) and non-dominant knee (dominant 22.8±6.8%, non-dominant 36.2±8.5%, p\<0.001). # Conclusion High demand on coordination and motor control during the lateral vertical jump and inherent limb dominance may explain different intra-limb strategies for task performance despite jump height symmetry. Non-dominant affinity for stability and dominant compensatory performance may neutralize potential asymmetries. Implications for symmetry in observable outcomes such as jump height must consider underlying internal asymmetries. # Levels of Evidence 3B # Clinical Relevance Symmetrical findings on functional tasks have underlying internal asymmetries observed here in female adolescent soccer players. The lateral vertical jump may highlight these internal asymmetries (hip- versus knee-dominant movement strategies) due to the high coordinative demand to perform the task. Clinicians should be cognizant of underlying, potentially inherent, asymmetries even when observing functional symmetry in a task. # What is known about the subject Female adolescent soccer players are a high-risk cohort for sustaining anterior cruciate ligament injuries. Limb dominance may play a role in the performance of functional tasks, and limb dominance in soccer players is quite specialized: the dominant limb is the preferred kicking limb, while the non-dominant limb is the preferred stabilizing limb (plant leg). Functional performance in female soccer players has been studied in kicking, dribbling, sprinting, change of direction, and jumping -- however, these tasks were measured independent of limb dominance. It remains to be seen how unilateral functional tasks may be affected by limb dominance in female adolescent soccer players. # What this study adds to existing knowledge This study provides data on functional performance relative to limb dominance in female adolescent soccer players, and captures the lateral vertical jump task in both inter- and intra-limb measures. This highlights that intra-limb strategies to perform a coordinated motor task may be different between limbs, herein attributed to limb dominance. Even if gross motor outputs between limbs are symmetrical (i.e. jump height), the underlying movement strategies to achieve that output may be different (hip- versus knee-dominant movement strategies). These findings are important to research on functional performance measures related to attaining between-limb symmetry, as measures of energy generation contribution open the door for a more thorough understanding of joint-by-joint intra-limb contributions during a functional task

    The evolution of the dust and gas content in galaxies

    Get PDF
    We use deep Herschel observations taken with both PACS and SPIRE imaging cameras to estimate the dust mass of a sample of galaxies extracted from the GOODS-S, GOODS-N and the COSMOS fields. We divide the redshift–stellar mass (M star )–star formation rate (SFR) parameter space into small bins and investigate average properties over this grid. In the first part of the work we investigate the scaling relations between dust mass, stellar mass and SFR out to z = 2.5. No clear evolution of the dust mass with redshift is observed at a given SFR and stellar mass. We find a tight correlation between the SFR and the dust mass, which, under reasonable assumptions, is likely a consequence of the Schmidt-Kennicutt (S-K) relation. The previously observed correlation between the stellar content and the dust content flattens or sometimes disappears when considering galaxies with the same SFR. Our finding suggests that most of the correlation between dust mass and stellar mass obtained by previous studies is likely a consequence of the correlation between the dust mass and the SFR combined with the main sequence, i.e., the tight relation observed between the stellar mass and the SFR and followed by the majority of star-forming galaxies. We then investigate the gas content as inferred from dust mass measurements. We convert the dust mass into gas mass by assuming that the dust-to-gas ratio scales linearly with the gas metallicity (as supported by many observations). For normal star-forming galaxies (on the main sequence) the inferred relation between the SFR and the gas mass (integrated S-K relation) broadly agrees with the results of previous studies based on CO measurements, despite the completely different approaches. We observe that all galaxies in the sample follow, within uncertainties, the same S-K relation. However, when investigated in redshift intervals, the S-K relation shows a moderate, but significant redshift evolution. The bulk of the galaxy population at z ∌ 2 converts gas into stars with an efficiency (star formation efficiency, SFE = SFR/M gas , equal to the inverse of the depletion time) about 5 times higher than at z ∌ 0. However, it is not clear what fraction of such variation of the SFE is due to an intrinsic redshift evolution and what fraction is simply a consequence of high-z galaxies having, on average, higher SFR, combined with thesuper-linear slope of the S-K relation (whileother studies finda linear slope). We confirm that the gas fraction (f gas = M gas /(M gas + M star )) decreases with stellar mass and increases with the SFR. We observe no evolution with redshift once M star and SFR are fixed. We explain these trends by introducing a universal relation between gas fraction, stellar mass and SFR that does not evolve with redshift, at least out to z ∌ 2.5. Galaxies move across this relation as their gas content evolves across the cosmic epochs. We use the 3D fundamental f gas –M star –SFR relation, along with the evolution of the main sequence with redshift, to estimate the evolution of the gas fraction in the average population of galaxies as a function of redshift and as a function of stellar mass: we find that M star > ∌ 10 11 M ? galaxies show the strongest evolution at z > ∌ 1.3 and a flatter trend at lower redshift, while f gas decreases more regularly over the entire redshift range probed in M star < ∌ 10 11 Mo galaxies, in agreement with a downsizing scenario

    Gas Accretion and Star Formation Rates

    Full text link
    Cosmological numerical simulations of galaxy evolution show that accretion of metal-poor gas from the cosmic web drives the star formation in galaxy disks. Unfortunately, the observational support for this theoretical prediction is still indirect, and modeling and analysis are required to identify hints as actual signs of star-formation feeding from metal-poor gas accretion. Thus, a meticulous interpretation of the observations is crucial, and this observational review begins with a simple theoretical description of the physical process and the key ingredients it involves, including the properties of the accreted gas and of the star-formation that it induces. A number of observations pointing out the connection between metal-poor gas accretion and star-formation are analyzed, specifically, the short gas consumption time-scale compared to the age of the stellar populations, the fundamental metallicity relationship, the relationship between disk morphology and gas metallicity, the existence of metallicity drops in starbursts of star-forming galaxies, the so-called G dwarf problem, the existence of a minimum metallicity for the star-forming gas in the local universe, the origin of the alpha-enhanced gas forming stars in the local universe, the metallicity of the quiescent BCDs, and the direct measurements of gas accretion onto galaxies. A final section discusses intrinsic difficulties to obtain direct observational evidence, and points out alternative observational pathways to further consolidate the current ideas.Comment: Invited review to appear in Gas Accretion onto Galaxies, Astrophysics and Space Science Library, eds. A. J. Fox & R. Dav\'e, to be published by Springe

    Charity registration and reporting:a cross-Jurisdictional and theoretical analysis of regulatory impact

    Get PDF
    Increasingly governments worldwide regulate charities, seeking to restrict the number of organizations claiming taxation exemptions, reduce abuse of state support and fraud. Under public interest theory governments may increase philanthropy through public trust and confidence in charities. Under public choice theory regulators will maximize political returns, ‘manage’ charity-government relationships, and avoid regulatory capture. Phillips and Smith (2014) suggest that charities’ regulatory regimes should coalesce, despite jurisdictional diversity. We analyse charity regulatory regimes against underlining theories of regulation, and assess regulatory costs and benefits. Thus regulators can reduce regulatory inefficiency, and balance accountability and transparency demands with charities’ abilities to deliver

    A dusty star-forming galaxy at <i>z</i> = 6 revealed by strong gravitational lensing

    Get PDF
    Since their discovery, submillimetre-selected galaxies have revolutionized the field of galaxy formation and evolution. From the hundreds of square degrees mapped at submillimetre wavelengths, only a handful of sources have been confirmed to lie at z > 5 and only two at z ≄ 6. All of these submillimetre galaxies are rare examples of extreme starburst galaxies with star formation rates of ≳1,000 M⊙ yr−1 and therefore are not representative of the general population of dusty star-forming galaxies. Consequently, our understanding of the nature of these sources, at the earliest epochs, is still incomplete. Here, we report the spectroscopic identification of a gravitationally amplified (Ό = 9.3 ± 1.0) dusty star-forming galaxy at z = 6.027. After correcting for gravitational lensing, we derive an intrinsic less-extreme star formation rate of 380 ± 50 M⊙ yr−1 for this source and find that its gas and dust properties are similar to those measured for local ultra luminous infrared galaxies, extending the local trends to a poorly explored territory in the early Universe. The star-formation efficiency of this galaxy is similar to those measured in its local analogues, despite a ~12 Gyr difference in cosmic time

    Iron uptake and transport across physiological barriers

    Full text link

    A conceptual model for the blooming behavior and persistence of the benthic mat-forming diatom Didymosphenia geminatain oligotrophic streams

    No full text
    [1] The benthic, mat-forming diatom Didymosphenia geminata has the unique ability to produce large amounts of algal biomass under oligotrophic conditions in cold, fast flowing streams and rivers. This presents an ecological paradox that challenges our current understanding of stream ecosystem dynamics. Our understanding of the drivers of D. geminata ecology is still limited. Here we present a conceptual model for the blooming behavior and persistence of this species to advance scientific understanding of strategies for life in fast flowing oligotrophic waters and support the design of future research and mitigation measures for nuisance algal blooms. The conceptual model is based on a synthesis of data and ideas from a range of disciplines including hydrology, geomorphology, biogeochemistry, and ecology. The conceptual model highlights the role of water chemistry, river morphology, and flow thresholds in defining the habitat window for D. geminata. We propose that bed disturbance is a primary control on accumulation and persistence of D. geminata and that the removal threshold can be determined by synthesizing site-specific information on hydrology and geomorphology. Further, we propose that a key to understanding the didymo paradox is the separation of cellular reproduction and mat morphology with specific controls acting in respect of the different processes
    • 

    corecore