140 research outputs found

    The application of successional theory-based management to Minnesota prairie sites degraded by invasive plant species

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    A thesis project at Camp Ripley Army National Guard Training Site will address the effectiveness of directing succession as a means of restoring areas dominated by perennial terrestrial invasive species: Common Tansy (Tanacetum vulgare) and Spotted Knapweed, (Centaurea stoebe ssp. micranthos). The purpose of this project is to design and implement an experiment that will test different combinations of treatments that alter the three factors of site availability, species availability, and species performance, as defined by Pickett et al. (1987) and Sheley et al. (2003). Altering these three factors is done with the goal of restoring perennial invasive-species-dominated areas into a native plant community. My experimental objective is to determine if succession-based management strategies are an appropriate methodology for the restoration of Minnesota prairie ecosystems that are impacted by invasive species, as it has been shown that invasive species can severely degrade ecosystems. The research question further involves determining which practices within this framework of succession are most effective in restoring Minnesota prairie ecosystems that are degraded by the presence of these invasive plant species. This experiment took place in spring 2010 through fall 2011 and incorporated site manipulation of four seedbed preparations, two cover crop types, and two seed dispersal methods. The addition of a fourth factor involved the application of a selective herbicide, Milestone, to half of each plot. Statistical analysis determined that by the end of data collection in August 2011, all levels from the first three factors in the experimental design did not significantly reduce either invasive species. The application of the fourth factor did significantly reduce both invasive species’ mean percent cover. However, a negative consequence of this selective herbicide is reduction in species richness in plots and increase in non-native grass cover. It is recommended due to the nature of succession, continued monitoring, data collection, and analysis occur on experimental sites

    Cumulative stress in childhood is associated with blunted reward-related brain activity in adulthood

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    Early life stress (ELS) is strongly associated with negative outcomes in adulthood, including reduced motivation and increased negative mood. The mechanisms mediating these relations, however, are poorly understood. We examined the relation between exposure to ELS and reward-related brain activity, which is known to predict motivation and mood, at age 26, in a sample followed since kindergarten with annual assessments. Using functional neuroimaging, we assayed individual differences in the activity of the ventral striatum (VS) during the processing of monetary rewards associated with a simple card-guessing task, in a sample of 72 male participants. We examined associations between a cumulative measure of ELS exposure and VS activity in adulthood. We found that greater levels of cumulative stress during childhood and adolescence predicted lower reward-related VS activity in adulthood. Extending this general developmental pattern, we found that exposure to stress early in development (between kindergarten and grade 3) was significantly associated with variability in adult VS activity. Our results provide an important demonstration that cumulative life stress, especially during this childhood period, is associated with blunted reward-related VS activity in adulthood. These differences suggest neurobiological pathways through which a history of ELS may contribute to reduced motivation and increased negative mood

    Individual differences in regulatory focus predict neural response to reward

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    Although goal pursuit is related to both functioning of the brain's reward circuits and psychological factors, the literatures surrounding these concepts have often been separate. Here, we use the psychological construct of regulatory focus to investigate individual differences in neural response to reward. Regulatory focus theory proposes two motivational orientations for personal goal pursuit: (1) promotion, associated with sensitivity to potential gain, and (2) prevention, associated with sensitivity to potential loss. The monetary incentive delay task was used to manipulate reward circuit function, along with instructional framing corresponding to promotion and prevention in a within-subject design. We observed that the more promotion oriented an individual was, the lower their ventral striatum response to gain cues. Follow-up analyses revealed that greater promotion orientation was associated with decreased ventral striatum response even to no-value cues, suggesting that promotion orientation may be associated with relatively hypoactive reward system function. The findings are also likely to represent an interaction between the cognitive and motivational characteristics of the promotion system with the task demands. Prevention orientation did not correlate with ventral striatum response to gain cues, supporting the discriminant validity of regulatory focus theory. The results highlight a dynamic association between individual differences in self-regulation and reward system function

    Lower structural integrity of the uncinate fasciculus is associated with a history of child maltreatment and future psychological vulnerability to stress

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    Abstract The experience of child maltreatment is a significant risk factor for the development of later internalizing disorders such as depression and anxiety. This risk is particularly heightened after exposure to additional, more contemporaneous stress. While behavioral evidence exists for such “stress sensitization,” little is known about the mechanisms mediating such relationships, particularly within the brain. Here we report that the experience of child maltreatment independent of recent life stress, gender, and age is associated with reduced structural integrity of the uncinate fasciculus, a major white matter pathway between the amygdala and ventromedial prefrontal cortex, in young adults. We further demonstrate that individuals with lower uncinate fasciculus integrity at baseline who subsequently experience stressful life events report higher levels of internalizing symptomatology at follow-up. Our findings suggest a novel neurobiological mechanism linking child maltreatment with later internalizing symptoms, specifically altered structural connectivity within the brain's threat-detection and emotion-regulation circuitry

    Technical Note: Four‐dimensional deformable digital phantom for MRI sequence development

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    From Wiley via Jisc Publications RouterHistory: received 2021-02-04, rev-recd 2021-05-14, accepted 2021-05-26, pub-electronic 2021-08-02Article version: VoRPublication status: PublishedFunder: Engineering and Physical Sciences Research Council; Id: http://dx.doi.org/10.13039/501100000266; Grant(s): EP/R5131631/1Funder: NIHR Manchester Biomedical Research CentreFunder: Cancer Research UK; Id: http://dx.doi.org/10.13039/501100000289; Grant(s): A21993Abstract: Purpose: MR‐guided radiotherapy has different requirements for the images than diagnostic radiology, thus requiring development of novel imaging sequences. MRI simulation is an excellent tool for optimizing these new sequences; however, currently available software does not provide all the necessary features. In this paper, we present a digital framework for testing MRI sequences that incorporates anatomical structure, respiratory motion, and realistic presentation of MR physics. Methods: The extended Cardiac‐Torso (XCAT) software was used to create T1, T2, and proton density maps that formed the anatomical structure of the phantom. Respiratory motion model was based on the XCAT deformation vector fields, modified to create a motion model driven by a respiration signal. MRI simulation was carried out with JEMRIS, an open source Bloch simulator. We developed an extension for JEMRIS, which calculates the motion of each spin independently, allowing for deformable motion. Results: The performance of the framework was demonstrated through simulating the acquisition of a two‐dimensional (2D) cine and demonstrating expected motion ghosts from T2 weighted spin echo acquisitions with different respiratory patterns. All simulations were consistent with behavior previously described in literature. Simulations with deformable motion were not more time consuming than with rigid motion. Conclusions: We present a deformable four‐dimensional (4D) digital phantom framework for MR sequence development. The framework incorporates anatomical structure, realistic breathing patterns, deformable motion, and Bloch simulation to achieve accurate simulation of MRI. This method is particularly relevant for testing novel imaging sequences for the purpose of MR‐guided radiotherapy in lungs and abdomen

    Are categorical deniers different? Understanding demographic, personality, and psychological differences between denying and admitting sex offenders

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    The purpose of this study was to establish whether there were demographic, personality, or psychological differences between a sample of 40 incarcerated sex offenders in categorical denial and 37 sex offenders admitting responsibility in an Australian minimum-security unit. Categorical deniers had lower IQs, were older, and were more likely to be child molesters. Criminogenically, there were no differences between categorical deniers and those who admitted their offences in relation to Static-99 risk scores. Psychologically, offenders denying their offences were significantly more shame-prone, and likely to use externalization as a method of impression-management. They were also more compulsive than those admitting their offences, but less antisocial and sadistic, when compared on personality indices. The study is limited by the small sample size however implications for further research and the treatment of categorical deniers are discussed

    Essential Emergency and Critical Care: a consensus among global clinical experts.

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    BACKGROUND: Globally, critical illness results in millions of deaths every year. Although many of these deaths are potentially preventable, the basic, life-saving care of critically ill patients are often overlooked in health systems. Essential Emergency and Critical Care (EECC) has been devised as the care that should be provided to all critically ill patients in all hospitals in the world. EECC includes the effective care of low cost and low complexity for the identification and treatment of critically ill patients across all medical specialties. This study aimed to specify the content of EECC and additionally, given the surge of critical illness in the ongoing pandemic, the essential diagnosis-specific care for critically ill patients with COVID-19. METHODS: In a Delphi process, consensus (>90% agreement) was sought from a diverse panel of global clinical experts. The panel iteratively rated proposed treatments and actions based on previous guidelines and the WHO/ICRC's Basic Emergency Care. The output from the Delphi was adapted iteratively with specialist reviewers into a coherent and feasible package of clinical processes plus a list of hospital readiness requirements. RESULTS: The 269 experts in the Delphi panel had clinical experience in different acute medical specialties from 59 countries and from all resource settings. The agreed EECC package contains 40 clinical processes and 67 requirements, plus additions specific for COVID-19. CONCLUSION: The study has specified the content of care that should be provided to all critically ill patients. Implementing EECC could be an effective strategy for policy makers to reduce preventable deaths worldwide

    The effect of relative humidity on eddy covariance latent heat flux measurements and its implication for partitioning into transpiration and evaporation

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    While the eddy covariance (EC) technique is a well-established method for measuring water fluxes (i.e., evaporation or 'evapotranspiration’, ET), the measurement is susceptible to many uncertainties. One such issue is the potential underestimation of ET when relative humidity (RH) is high (>70%), due to low-pass filtering with some EC systems. Yet, this underestimation for different types of EC systems (e.g. open-path or closed-path sensors) has not been characterized for synthesis datasets such as the widely used FLUXNET2015 dataset. Here, we assess the RH-associated underestimation of latent heat fluxes (LE, or ET) from different EC systems for 163 sites in the FLUXNET2015 dataset. We found that the LE underestimation is most apparent during hours when RH is higher than 70%, predominantly observed at sites using closed-path EC systems, but the extent of the LE underestimation is highly site-specific. We then propose a machine learning based method to correct for this underestimation, and compare it to two energy balance closure based LE correction approaches (Bowen ratio correction, BRC, and attributing all errors to LE). Our correction increases LE by 189% for closed-path sites at high RH (>90%), while BRC increases LE by around 30% for all RH conditions. Additionally, we assess the influence of these corrections on ET-based transpiration (T) estimates using two different ET partitioning methods. Results show opposite responses (increasing vs. slightly decreasing T-to-ET ratios, T/ET) between the two methods when comparing T based on corrected and uncorrected LE. Overall, our results demonstrate the existence of a high RH bias in water fluxes in the FLUXNET2015 dataset and suggest that this bias is a pronounced source of uncertainty in ET measurements to be considered when estimating ecosystem T/ET and WUE.Peer reviewe

    A life course approach to injury prevention: a "lens and telescope" conceptual model

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    <p>Abstract</p> <p>Background</p> <p>Although life course epidemiology is increasingly employed to conceptualize the determinants of health, the implications of this approach for strategies to reduce the burden of injuries have received little recognition to date.</p> <p>Methods</p> <p>The authors reviewed core injury concepts and the principles of the life course approach. Based on this understanding, a conceptual model was developed, to provide a holistic view of the mechanisms that underlie the accumulation of injury risk and their consequences over the life course.</p> <p>Results</p> <p>A "lens and telescope" model is proposed that particularly draws on (a) the extended temporal dimension inherent in the life course approach, with links between exposures and outcomes that span many years, or even generations, and (b) an ecological perspective, according to which the contexts in which individuals live are critical, as are changes in those contexts over time.</p> <p>Conclusions</p> <p>By explicitly examining longer-term, intergenerational and ecological perspectives, life course concepts can inform and strengthen traditional approaches to injury prevention and control that have a strong focus on proximal factors. The model proposed also serves as a tool to identify intervention strategies that have co-benefits for other areas of health.</p
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