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Lianas Reduce Tree Height With Negative Consequences for Carbon Storage and Growth Estimates
No full textCurrent evidence suggests that liana (woody vine) competition with trees could be threatening the carbon sink by reducing carbon uptake and storage in tropical forests. Previous studies investigating forest demography in liana removal experiments have, however, assumed similar allometries for trees, regardless of the amount of lianas they support. Yet, recent observations suggest that liana load may alter tree shape and structure, including height, which could result in an underestimation of the liana effects on forest carbon stocks and tree growth. In this study, we used terrestrial laser scanning (TLS) in a liana removal experiment in Gigante Peninsula, Panama, collected 11 years after removal to quantify the liana effect on tree height allometry. Furthermore, we assessed how the liana impact on tree allometry affects the estimates of carbon storage and sequestration. We fitted multiple tree height–diameter allometric relationships with a hierarchical Bayesian approach and combined the best resulting allometric model with inventories to estimate plot-level biomass stocks and their changes over time. For the same diameter at breast height, we found the trees to be 1.8 m shorter on average in the control plots compared to those in the removal plots, indicating a substantial liana effect on tree height. Converting these height differences through the use of allometric models and inventory data led to a reduction in tree biomass stock estimates in the control plots of 1.8 Mg C ha,−1 while they increased by 2.5 Mg C ha−1 in removal plots 10 years after removal. TLS-derived allometries led to estimates of tree biomass growth and tree biomass increment, respectively, 27.1% and 21.8% higher than when treatment-specific height allometries were not accounted for. Synthesis. The use of TLS in a unique experiment site provides strong experimental evidence that lianas change tree allometry, which has repercussions for estimating the capacity of forests to store and accumulate carbon. Our findings highlight the importance of accounting for liana-induced effects on tree shape and structure when using allometric equations to accurately estimate the impact of lianas on forest carbon dynamics
Cumulative Effects of H\u3csup\u3e+\u3c/sup\u3e and P\u3csub\u3ei\u3c/sub\u3e on Force and Power of Skeletal Muscle Fibres from Young and Older Adults
No full textThe cellular causes of the age-related loss in power output and increased fatigability are unresolved. We previously observed that the depressive effects of hydrogen (H+) (pH 6.2) and inorganic phosphate (Pi) (30 mm) did not differ in muscle fibres from young and older men. However, the effects may have been saturated in the severe fatigue-mimicking condition, potentially masking age differences in the sensitivity of the cross-bridge to these metabolites. Thus, we compared the contractile mechanics of muscle fibres from the vastus lateralis of 13 young (20–32 years, seven women) and 12 older adults (70–90 years, six women) in conditions mimicking quiescent muscle and a range of elevated H+ (pH 6.8–6.6–6.2) and Pi (12–20–30 mm). The older adult knee extensor muscles showed hallmark signs of ageing, including 19% lower thigh lean mass, 60% lower power and a greater fatigability compared to young adult muscles. Progressively increasing concentrations of H+ and Pi in the chemically-permeabilized fibre experiments caused a linear decrease in fibre force, velocity and power; however, the effects did not differ with age or sex. Fast fibre cross-sectional area was 41% smaller in older compared to young adults, which corresponded with lower absolute power. Size-specific power was greater in fibres from older compared to young adults, indicating the age-related decline in absolute power was explained by differences in fibre size. These data suggest the age-related loss in power is determined primarily by fast fibre atrophy in men and women, but the age-related increase in fatigability cannot be explained by an increased sensitivity of the cross-bridge to H+ and Pi. Key points The causes of the age-related loss in muscle power output and the increase in fatigability during dynamic exercise remain elusive. We show that progressively increasing concentrations of hydrogen (H+) and inorganic phosphate (Pi) causes a linear decrease in muscle fibre force, velocity and power, but the depressive effects of these metabolites on cross-bridge function did not differ in fibres from older compared to young adults across a range of fatigue-mimicking conditions. We also found peak absolute power did not differ in slow fibres from young and older adults but it was ∼33% lower in older adult fast fibres, which was explained entirely by age differences in fibre size. These data suggest that fast fibre atrophy is a major factor contributing to the loss in power of older men and women, but that the age-related increase in fatigability cannot be explained by an increased sensitivity of the cross-bridge to H+ and Pi
Unemployed Black/African Americans With Disabilities’ Treatment Acquisition for Substance Use Disorder and Serious Mental Illness
No full textBlack/African Americans with disabilities who live with substance use disorder and/or serious mental illness are an underserved population in mental health treatment. We conducted a quantitative analysis using the 2022 National Survey on Drug Use and Health (N = 317) to identify treatment trends and interpreted results using DisCrit and the Behavioral Model of Health Services Use. We offer discussion and implications to increase service access for this population
Drying Reduces the Total PFAS Concentration In Biosolids and Alters the PFAS Profile
No full textWhile per- and polyfluoroalkyl substances (PFAS) are not actually generated at water resource recovery facilities (WRRFs), utilities are being forced to consider PFAS in biosolids management plans due to mounting political pressure and pending regulations. Emerging thermal technologies including pyrolysis, gasification, and super critical water oxidation have garnered recent attention for PFAS destruction. Drying, however, is a conventional technology that might also be a tool for utilities to manage PFAS in biosolids, but research on the impacts of drying on PFAS in biosolids is scarce. The objective of this research was to determine how drying affected the fate of PFAS in biosolids. Full-scale sampling was paired with lab-scale oven drying experiments to understand the impact of drying on measurable PFAS in biosolids. Overall, drying substantially reduced the total PFAS concentration in biosolids. PFAS removal during a full-scale facility\u27s drying process matched the removal achieved when solids were taken from that facility and dried in a lab-scale oven instead, with average PFAS removal being approximately 80%. Precursors to perfluoroalkyl acids (PFAAs), primarily 5 : 3 fluorotelomer carboxylic acid (FTCA) and 6 : 2 FTCA, as well as perfluorooctane sulfonic acid (PFOS) were substantially reduced between pre-drying and post-drying triplicate samples. Additional lab-scale oven drying experiments corroborated that measurable PFAS were removed from biosolids collected from three different utilities. Drying experiments at 30 °C and 105 °C revealed that the PFAS profiles were similar, but PFAS concentrations were lower in the 105 °C samples compared to 30 °C samples. While more research is necessary to determine and validate the removal mechanism, drying could be a viable technology to reduce measurable PFAS levels in biosolids to concentrations below guidelines for land application
A Novel Robotic Pedaling Paradigm to Improve Lower Limb Movement Post-Stroke
No full textPrior work in our lab revealed that while impaired paretic neuromuscular output contributes to movement difficulties post-stroke, compensation is more related to interlimb coordination (ILC) deficits. Specifically, ILC deficits were revealed in the context of lower limb split-crank pedaling. Participants who demonstrated larger levels of compensation during a conventional, solid-crank pedaling task also demonstrated larger deficits in ILC i.e. maintaining a 180-degree phase relationship during split-crank. To address this deficit, our lab created a novel, split-crank pedaling robot named CUped. CUped (pronounced Cupid) is so called because it compels use of the paretic limb during a movement that resembles pedaling. CUped can create a training environment where ILC can be practiced while emphasizing output of the paretic limb. The purpose of this dissertation was to determine appropriate robotic control schemes and visual feedback methods for CUped. To achieve this purpose, we evaluated ILC, paretic work output, and velocity pedaling strategy during split-crank pedaling. Aim 1 investigated three proportional control schemes: Assist, Resist, and Assist+Resist. Control schemes provided torque to restore 180-degree phasing proportional to the phasing error. Assist provided forward-direction torque to the lagging limb while resist provided reverse-direction torque to the leading limb. Assist+Resist provided both control actions. Results indicated that Assist+Resist facilitated the lowest interlimb phasing errors while mitigating loss of paretic limb work. However, participants adopted a suboptimal pedaling strategy and performance was not retained during Post-test. Aim 2 tested whether simple visual feedback could further reduce phasing error as well as mitigate suboptimal pedaling strategy and allow retention during Post. Additionally, a constant and randomly-varying error augmentation gain schedule was examined to determine whether pedaling could further be improved. Interestingly, neither simple visual feedback nor error augmentation improved performance. We hypothesized that simple visual feedback did not adequately provide saliency of the task goal relative to the displayed error. Thus, for Aim 3 we tested whether additional visual feedback elements of reward and punishment were sufficient to improve pedaling performance. Results indicated that participants do indeed improve pedaling performance when presented with simple visual feedback in addition to elements of reward and punishment. Overall, these studies demonstrate that CUped can provide a proper environment to promote therapeutic behavior as well as provide important knowledge about lower limb deficits after stroke needed to drive the development of CUped forward
Exploring and Engineering the Surface Microenvironment of Single-Atom Catalysts for Suzuki Cross-Couplings
No full textSingle-Atom Catalysts (SACs) are an emerging class of materials capable of bridging the gap between homogeneous and heterogeneous catalysts by mitigating disadvantages and providing the benefits of both. One field where SACs are receiving attention is for carbon-carbon cross-couplings, such as Suzuki reactions. While capable of performing these reactions, SACs lack the fine control afforded to homogenous catalysts through the use of ligands. Much of the SACs surface will have little interaction with reactants, and there is no way to effectively control the microenvironment surrounding the active site. Our approach seeks to understand the interactions between an SAC and the reaction substrates by modifying the surface of the SAC to enhance surface/substrate interaction and through understanding the factors that drive the selectivity of a reaction in comparison to a reaction with a homogeneous catalyst. A brief exploration of SACs in given in Chapter 1, before Chapter 2 begins by discussing the synthesis and characterization of our SAC, Pd/CeO¬2. Chapter 2 then investigates our SAC modification approach, where catechol monolayers are deposited on the surface of an SAC and increase the activity through π-stacking effects. The enhancement effect is lost as bulkier ligands are used, presumably due to steric hinderance. Chapter 3 begins our exploration of regioselectivity, where a reaction with two reactive sites is studied, to determine which product is favored. In this study, the catalysts Pd/CeO2 and Pd(OAc)¬2/4PPh3 are systematically compared under a multitude of conditions to assess the driving forces behind selectivity and activity, as well as deepening the understanding of the differences between a typical homogeneous catalyst and an SAC. Chapter 4 brings together the knowledge gained from Chapters 2 and 3 by utilizing carboxylic acid monolayers to control the regioselectivity of a reaction through π-stacking interactions between pyridine carboxylic acids and nitrogen containing aryl halides. Chapters 5 draws conclusions from the entire body of work, and Chapter 6 discusses possible future directions for investigating surface interactions on SACs and for using monolayers to enhance SAC performance
Attenuation Characteristics of Military Boots
No full textThis study evaluated commercially available military-style boots permitted for use in combat, against a military-issued boot. Testing simulated high-dynamic foot-loading scenarios using two anthropomorphic test devices (ATDs): Hybrid-III-50% (HIII) and Mil-Lx. The goal was to assess differences in force attenuation measurements. The commercially available boots were evaluated with both ATDs, while the military-issued boot was assessed with the Mil-Lx, with HIII data references from prior studies. All boots underwent pendulum impacts to the plantar surface of the boot, generating an axial force along the tibia axis, across a five-condition test matrix. The repeatability protocol ensured that neither the boots nor ATDs sustained damage, aligning with previous studies. Test conditions varied by pendulum mass (3.38–6.66 kg), velocity (4.75–10.0 m/s), and energy input (42–300 J). Results were compared to barefoot impacts with each leg. The Mil-Lx ATD results indicated that while each boot demonstrated various levels of peak force attenuation across five conditions, the differences were not significant (p\u3e0.05). Conversely, the commercially available boots assessed with the HIII exhibited significantly different attenuation values (p\u3c 0.05). The two ATDs also recorded significantly different attenuation values (p\u3c 0.05). HIII attenuations were more closely related to impact velocity while Mil-Lx attenuations aligned with pendulum mass. To investigate these trends, a lumped parameter model of the Mil-Lx ATD was developed to characterize the mechanical properties of its compliant element. The model provides insight into the surrogate tibia’s spring and damping behavior under axial loading. Findings suggest that all boots attenuate impact forces effectively, improving force distribution compared to barefoot configurations. Differences in attenuation between the commercially available boots may be attributed to design variations. The HIII and Mil-Lx indicated different trends in attenuation results, suggesting ATD design differences influenced results. The Mil-Lx produced more consistent, conservative attenuation values, which aligned with previous PMHS studies. The lumped-parameter model closely replicated experimental forces for the unbooted Mil-Lx
Long-Term Bone Changes at Edentulous Sites
No full textBACKGROUND: Tooth loss is a debilitating occurrence that may affect the patient’s emotional and mental well-being. Delays in necessary restorative treatment may occur dependent on the patient’s finances or other elaborate dental treatment plans. Prosthetically guided implants have become the standard of care regarding definitive treatment, however there is a lack of evidence discussing the stability of edentulous sites if deferment of treatment is required. OBJECTIVE: The aim of this study is to measure long-term changes of the edentulous alveolar ridge (height and width) and anatomical structures (e.g. sinus floor, inferior alveolar canal). METHODS: Charts of patients with at least two Cone Beam Computed Tomographies (CBCTs) taken 12 months apart within a 10-year period were reviewed. If included, the CBCTs were anonymized and imported into the Dolphin Imaging Premium Software, were superimposed, and linear measurements of height and width (3mm and 5mm from alveolar crest) and change in sinus floor location were calculated. The landmarks used were the anterior and posterior nasal spines for maxilla and the superior border of the mental foramina (mandible). RESULTS: Eighty-three patients (age at first CBCT: 62.5±0.7 years; 44 females) contributed to the study with 253 sites (148 molar, 55 premolar, 14 canine, 36 anterior) in CBCTs recorded 26.3±1 months apart. Alveolar bone height changes were 0.49±0.05mm (coronal; p\u3c 0.0001) and 0.42±0.05mm (sagittal; p\u3c 0.0001). The difference between the mandible and maxilla was significant (coronal; p\u3c 0.0001) and sagittal; p\u3c 0.0001). Width changes were 0.31±0.04mm (3mm; p\u3c 0.0001) and 0.24±0.03mm (5mm; p\u3c 0.0001), respectively. The difference between the maxillary and mandibular arch was not significant (3mm; p=0.21 and 5mm; p=0.94). Sinus floor location minimally changed by 0.2±0.02mm (coronal; p=0.51) and -0.02±0.04mm (sagittal; p=0.58). CONCLUSION: Alveolar bone height and width of established edentulous sites undergo minimal changes for at least a 2-year period. Although mandibular site height changes are statistically significantly greater than in maxillary sites, the differences are clinically insignificant
(WP 2025-02) How Does the FOMC Form Forecasts? An Adaptive Learning Approach Utilizing SEP Data
No full textThis paper examines how FOMC participants construct their Summary of Economic Projections (SEP) forecasts. FOMC expectations are assumed to contain two components: (1) an endogenous part that follows an adaptive learning model and (2) an exogenous part defined as sentiment (waves of optimism and/or pessimism). The results include key policy takeaways. The forecasts of FOMC members are responsive to new economic information. Their sentiment about future GDP growth and inflation also displays persistence and is correlated with each other. Moreover, FOMC participants rely more on their endogenous/learning model to form expectations. However, sentiment plays a larger role during and around recessions