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1.
J Man Manip Ther ; 31(1): 38-45, 2023 02.
Article in English | MEDLINE | ID: mdl-35603569

ABSTRACT

INTRODUCTION: Self-efficacy is a determinant of function and pain outcomes in patients with chronic low back pain receiving physiotherapy. The McKenzie approach is an effective intervention for patients with back pain that may affect self-efficacy. Study aims were to determine if, among patients with back pain being managed by McKenzie-credentialed physiotherapists: intake self-efficacy is correlated with intake function and pain; intake self-efficacy is associated with changes in function and pain during treatment; self-efficacy improves during treatment; and improvements in self-efficacy during treatment are associated with improvements in function and pain at discharge. METHODS: Two-hundred-eighty-two subjects with chronic low back pain seen by McKenzie-credentialed clinicians provided data on self-efficacy, function and pain at intake and discharge. RESULTS: Self-efficacy was correlated with function and pain at intake; however, intake self-efficacy was not associated with function or pain outcomes. Self-efficacy increased during treatment. This increase was associated with improvements in function and pain at discharge. CONCLUSION: While intake self-efficacy was associated with function and pain when initiating physiotherapy, it did not result in improved treatment outcomes. Specific interventions may be necessary to improve self-efficacy. The increases in self-efficacy observed during treatment were associated with improvements in function and pain outcomes at discharge.


Subject(s)
Low Back Pain , Physical Therapists , Humans , Low Back Pain/therapy , Prospective Studies , Physical Therapy Modalities , Treatment Outcome
2.
J Geophys Res Planets ; 127(11): e2022JE007194, 2022 Nov.
Article in English | MEDLINE | ID: mdl-36582809

ABSTRACT

Nearly half a century ago, two papers postulated the likelihood of lunar lava tube caves using mathematical models. Today, armed with an array of orbiting and fly-by satellites and survey instrumentation, we have now acquired cave data across our solar system-including the identification of potential cave entrances on the Moon, Mars, and at least nine other planetary bodies. These discoveries gave rise to the study of planetary caves. To help advance this field, we leveraged the expertise of an interdisciplinary group to identify a strategy to explore caves beyond Earth. Focusing primarily on astrobiology, the cave environment, geology, robotics, instrumentation, and human exploration, our goal was to produce a framework to guide this subdiscipline through at least the next decade. To do this, we first assembled a list of 198 science and engineering questions. Then, through a series of social surveys, 114 scientists and engineers winnowed down the list to the top 53 highest priority questions. This exercise resulted in identifying emerging and crucial research areas that require robust development to ultimately support a robotic mission to a planetary cave-principally the Moon and/or Mars. With the necessary financial investment and institutional support, the research and technological development required to achieve these necessary advancements over the next decade are attainable. Subsequently, we will be positioned to robotically examine lunar caves and search for evidence of life within Martian caves; in turn, this will set the stage for human exploration and potential habitation of both the lunar and Martian subsurface.

3.
Front Psychol ; 12: 732347, 2021.
Article in English | MEDLINE | ID: mdl-34867613

ABSTRACT

In 2016, 10 universities launched a Networked Improvement Community (NIC) aimed at increasing the number of scholars from Alliances for Graduate Education and the Professoriate (AGEP) populations entering science, technology, engineering, and mathematics (STEM) faculty careers. NICs bring together stakeholders focused on a common goal to accelerate innovation through structured, ongoing intervention development, implementation, and refinement. We theorized a NIC organizational structure would aid understandings of a complex problem in different contexts and accelerate opportunities to develop and improve interventions to address the problem. A distinctive feature of this NIC is its diverse institutional composition of public and private, predominantly white institutions, a historically Black university, a Hispanic-serving institution, and land grant institutions located across eight states and Washington, DC, United States. NIC members hold different positions within their institutions and have access to varied levers of change. Among the many lessons learned through this community case study, analyzing and addressing failed strategies is as equally important to a healthy NIC as is sharing learning from successful interventions. We initially relied on pre-existing relationships and assumptions about how we would work together, rather than making explicit how the NIC would develop, establish norms, understand common processes, and manage changing relationships. We had varied understandings of the depth of campus differences, sometimes resulting in frustrations about the disparate progress on goals. NIC structures require significant engagement with the group, often more intensive than traditional multi-institution organizational structures. They require time to develop and ongoing maintenance in order to advance the work. We continue to reevaluate our model for leadership, climate, diversity, conflict resolution, engagement, decision-making, roles, and data, leading to increased investment in the success of all NIC institutions. Our NIC has evolved from the traditional NIC model to become the Center for the Integration of Research, Teaching and Learning (CIRTL) AGEP NIC model with five key characteristics: (1) A well-specified aim, (2) An understanding of systems, including a variety of contexts and different organizations, (3) A culture and practice of shared leadership and inclusivity, (4) The use of data reflecting different institutional contexts, and (5) The ability to accelerate infrastructure and interventions. We conclude with recommendations for those considering developing a NIC to promote diversity, equity, and inclusion efforts.

4.
Musculoskeletal Care ; 18(1): 46-52, 2020 03.
Article in English | MEDLINE | ID: mdl-31799798

ABSTRACT

OBJECTIVES: Graded activity and graded exposure in vivo are recommended cognitive behavioural approaches to improve function and pain outcomes for patients receiving physiotherapy for chronic nonspecific neck pain. The McKenzie method is a common treatment approach for patients with neck pain. The study objectives were to examine associations between interventions with graded activity and/or graded exposure, as determined by the treating physiotherapist, and function and pain outcomes for patients with chronic nonspecific neck pain managed by clinicians with credentials in the McKenzie approach. METHOD: A cohort study was carried out, in which subjects (n = 366) with chronic nonspecific neck pain completed intake surveys (i.e., the Neck Functional Status Computerized Adaptive Test and the Numeric Pain Rating Scale), and questions related to their demographic, lifestyle and health status. Treatment with graded activity/graded exposure during the episode of care was recorded. Function and pain measures were repeated at discharge. Multivariable models examining associations between patients receiving versus not receiving graded activity/graded exposure, and pain and function outcomes were constructed, controlling for potential confounding effects. RESULTS: Despite statistical significance, there were no clinically relevant differences between treatment versus no treatment with graded activity/graded exposure, and function or pain outcomes. CONCLUSION: There is insufficient evidence to suggest that patients being managed with McKenzie methods will attain clinically relevant improvements in function or pain outcomes when augmenting treatment with graded activity and/or graded exposure when the choice to intervene with these cognitive behavioural approaches is determined by the treating physiotherapist.


Subject(s)
Chronic Pain/therapy , Cognitive Behavioral Therapy , Neck Pain/therapy , Physical Therapy Modalities , Adolescent , Adult , Aged , Chronic Pain/physiopathology , Cohort Studies , Female , Humans , Male , Middle Aged , Neck Pain/physiopathology , Surveys and Questionnaires , Treatment Outcome , Young Adult
5.
Opt Lett ; 44(16): 4056-4059, 2019 Aug 15.
Article in English | MEDLINE | ID: mdl-31415546

ABSTRACT

We experimentally demonstrate on-chip supercontinuum generation in the visible region in angle-etched diamond waveguides. We measure an output spectrum spanning 670-920 nm in a 5-mm-long waveguide using 100-fs pulses with 187 pJ of incident pulse energy. Our fabrication technique, combined with diamond's broad transparency window, offers a potential route toward broadband supercontinuum generation in the UV domain.

6.
Sensors (Basel) ; 19(9)2019 May 13.
Article in English | MEDLINE | ID: mdl-31086036

ABSTRACT

Diamond is a good candidate for harsh environment sensing due to its high melting temperature, Young's modulus, and thermal conductivity. A sensor made of diamond will be even more promising when combined with some advantages of optical sensing (i.e., EMI inertness, high temperature operation, and miniaturization). We present a miniature diamond-based fiber optic pressure sensor fabricated using dual polymer-ceramic adhesives. The UV curable polymer and the heat-curing ceramic adhesive are employed for easy and reliable optical fiber mounting. The usage of the two different adhesives considerably improves the manufacturability and linearity of the sensor, while significantly decreasing the error from the temperature cross-sensitivity. Experimental study shows that the sensor exhibits good linearity over a pressure range of 2.0-9.5 psi with a sensitivity of 18.5 nm/psi (R2 = 0.9979). Around 275 °C of working temperature was achieved by using polymer/ceramic dual adhesives. The sensor can benefit many fronts that require miniature, low-cost, and high-accuracy sensors including biomedical and industrial applications. With an added antioxidation layer on the diamond diaphragm, the sensor can also be applied for harsh environment applications due to the high melting temperature and Young's modulus of the material.

7.
ACS Appl Mater Interfaces ; 9(46): 39895-39900, 2017 Nov 22.
Article in English | MEDLINE | ID: mdl-29110457

ABSTRACT

Large-area hexagonal boron nitride (h-BN) can be grown on polycrystalline metallic substrates via chemical vapor deposition (CVD), but the impact of local inhomogeneities on the electrical properties of the h-BN and their effect in electronic devices is unknown. Conductive atomic force microscopy (CAFM) and probe station characterization show that the tunneling current across the h-BN stack fluctuates up to 3 orders of magnitude from one substrate (Pt) grain to another. Interestingly, the variability in the tunneling current across the h-BN within the same substrate grain is very low, which may enable the use of CVD-grown h-BN in ultra scaled technologies.

8.
Colloids Surf B Biointerfaces ; 145: 768-776, 2016 Sep 01.
Article in English | MEDLINE | ID: mdl-27295493

ABSTRACT

Topographical features are essential to neural interface for better neuron attachment and growth. This paper presents a facile and feasible route to fabricate an electroactive and biocompatible micro-patterned Single-walled carbon nanotube/poly(3,4-ethylenedioxythiophene) composite films (SWNT/PEDOT) for interface of neural electrodes. The uniform SWNT/PEDOT composite films with nanoscale pores and microscale grooves significantly enlarged the electrode-electrolyte interface, facilitated ion transfer within the bulk film, and more importantly, provided topology cues for the proliferation and differentiation of neural cells. Electrochemical analyses indicated that the introduction of PEDOT greatly improved the stability of the SWNT/PEDOT composite film and decreased the electrode/electrolyte interfacial impedance. Further, in vitro culture of rat pheochromocytoma (PC12) cells and MTT testing showed that the grooved SWNT/PEDOT composite film was non-toxic and favorable to guide the growth and extension of neurite. Our results demonstrated that the fabricated microscale groove patterns were not only beneficial in the development of models for nervous system biology, but also in creating therapeutic approaches for nerve injuries.


Subject(s)
Microelectrodes , Nanocomposites/chemistry , Nanotubes, Carbon/chemistry , Animals , Electrochemistry , Membranes, Artificial , Nanocomposites/adverse effects , Neurites/drug effects , PC12 Cells , Rats
9.
Mater Des ; 109: 242-250, 2016 Nov 05.
Article in English | MEDLINE | ID: mdl-28943692

ABSTRACT

Graphene-based inorganic composites have been attracting more and more attention since the attachment of inorganic nanoparticles instead of conducting polymeric materials to graphene sheets turns out higher capacitances and good capacity retention. Here we report a fast fabrication method to prepare NiO@graphene composite modified electrodes for supercapacitors. By this method, preparation of electrochemical active materials of NiO/graphene and modification of the electrode can be simultaneously performed, which is achieved separately by traditional method. Moreover, the problem of poor adhesion of active materials on the surface of the electrode can be well solved. The NiO particles introduced to the films exhibit pseudocapacitive behavior arising from the reversible Faradaic transitions of Ni(II)/Ni(III) and greatly improve the capacitance of the electrodes. With the increase in NiO content, highly reduced graphene can be obtained during cyclic voltammetry sweeping, leading to the increase in the electrode capacitance. The highest specific capacitance of the constructed electrodes can reach 1258 F/g at a current density of 5 A/g.

10.
New Phytol ; 188(4): 919-38, 2010 Dec.
Article in English | MEDLINE | ID: mdl-20958306

ABSTRACT

Conditional control of plant cell function and development relies on appropriate signal perception, signal integration and processing. The development of high throughput technologies such as proteomics and interactomics has enabled the identification of protein interaction networks that mediate signal processing from inputs to appropriate outputs. Such networks can be depicted in graphical representations using nodes and edges allowing for the immediate visualization and analysis of the network's topology. Hubs are network elements characterized by many edges (often degree grade k ≥ 5) which confer a degree of topological importance to them. The review introduces the concept of networks, hubs and bottlenecks and describes four examples from plant science in more detail, namely hubs in the redox regulatory network of the chloroplast with ferredoxin, thioredoxin and peroxiredoxin, in mitogen activated protein (MAP) kinase signal processing, in photomorphogenesis with the COP9 signalosome, COP1 and CDD, and monomeric GTPase function. Some guidance is provided to appropriate internet resources, web repositories, databases and their use. Plant networks can be generated from existing public databases and this type of analysis is valuable in support of existing hypotheses, or to allow for the generation of new concepts or ideas. However, intensive manual curating of in silico networks is still always necessary.


Subject(s)
Plant Proteins/metabolism , Plants/metabolism , Signal Transduction , Morphogenesis , Oxidation-Reduction , Plant Development , Plants/enzymology , Protein Binding
11.
Photosynth Res ; 105(3): 213-27, 2010 Sep.
Article in English | MEDLINE | ID: mdl-20614182

ABSTRACT

The goal of this study was to investigate the effects of light intensity, genotype, and various chemical treatments on chloroplast movement in guard cells of Arabidopsis thaliana leaves. After treatment at various light intensities (dark, low, and high light), leaf discs were fixed with glutaraldehyde, and imaged using confocal laser microscopy. Each chloroplast was assigned a horizontal (close to pore, center, or epidermal side) and vertical (outer, middle, inner) position. White light had a distinct effect on chloroplast positioning, most notably under high light (HL) when chloroplasts on the upper leaf surface of wild-type (WT) moved from epidermal and center positions toward the pore. This was not the case for phot1-5/phot2-1 or phot2-1 plants, thus phototropins are essential for chloroplast positioning in guard cells. In npq1-2 mutants, fewer chloroplasts moved to the pore position under HL than in WT plants, indicating that white light can affect chloroplast positioning also in a zeaxanthin-dependent way. Cytochalasin B inhibited the movement of chloroplasts to the pore under HL, while oryzalin did not, supporting the idea that actin plays a role in the movement. The movement along actin cables is dependent on CHUP1 since chloroplast positioning in chup1 was significantly altered. Abscisic acid (ABA) caused most chloroplasts in WT and phot1-5/phot2-1 to be localized in the center, middle part of the guard cells irrespective of light treatment. This indicates that not only light but also water stress influences chloroplast positioning.


Subject(s)
Abscisic Acid/pharmacology , Arabidopsis/metabolism , Chloroplasts/metabolism , Genotype , Light , Plant Leaves/metabolism , Arabidopsis/drug effects , Arabidopsis/genetics , Arabidopsis/radiation effects , Arabidopsis Proteins/genetics , Chloroplast Proteins , Chloroplasts/drug effects , Chloroplasts/genetics , Chloroplasts/radiation effects , Cytochalasin B/pharmacology , Dinitrobenzenes/pharmacology , Microfilament Proteins/genetics , Microscopy, Confocal , Phosphoproteins/genetics , Plant Growth Regulators/pharmacology , Plant Leaves/drug effects , Plant Leaves/genetics , Plant Leaves/radiation effects , Protein Serine-Threonine Kinases , Sulfanilamides/pharmacology , Xanthophylls/metabolism , Zeaxanthins
12.
J Exp Bot ; 59(9): 2285-97, 2008.
Article in English | MEDLINE | ID: mdl-18468985

ABSTRACT

The effects of chloroplast number and size on the capacity for blue light-dependent chloroplast movement, the ability to increase light absorption under low light, and the susceptibility to photoinhibition were investigated in Arabidopsis thaliana. Leaves of wild-type and chloroplast number mutants with mean chloroplast numbers ranging from 120 to two per mesophyll cell were analysed. Chloroplast movement was monitored as changes in light transmission through the leaves. Light transmission was used as an indicator of the ability of leaves to optimize light absorption. The ability of leaves to deal with 3 h of high light stress at 10 degrees C and their capacity to recover in low light was determined by measuring photochemical efficiencies of PSII using chlorophyll a fluorescence. Chloroplast movement was comparable in leaves ranging in chloroplast numbers from 120 to 30 per mesophyll cell: the final light transmission levels after exposure to 0.1 (accumulation response) and 100 micromol photons m(-2) s(-1) (avoidance response) were indistinguishable, the chloroplasts responded quickly to small increases in light intensity and the kinetics of movement were similar. However, when chloroplast numbers per mesophyll cell decreased to 18 or below, the accumulation response was significantly reduced. The avoidance response was only impaired in mutants with nine or fewer chloroplasts, both in terms of final transmission levels and the speed of movement. Only mutants lacking both blue light receptors (phot1/phot2) or those with drastically reduced chloroplast numbers and severely impacted avoidance responses showed a reduced ability to recover from high light stress.


Subject(s)
Arabidopsis/radiation effects , Chloroplasts/radiation effects , Light , Plant Leaves/radiation effects , Arabidopsis/genetics , Arabidopsis/physiology , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Base Sequence , Chloroplasts/chemistry , Chloroplasts/genetics , Chloroplasts/physiology , Plant Leaves/genetics , Plant Leaves/physiology , Sequence Alignment
13.
J Am Dent Assoc ; 137(5): 610-8, 2006 May.
Article in English | MEDLINE | ID: mdl-16739540

ABSTRACT

BACKGROUND: The greatest threats to developing teeth are dental caries and traumatic injury. A primary goal of all restorative treatment is to maintain pulp vitality so that normal root development or apexogenesis can occur. If pulpal exposure occurs, then a pulpotomy procedure aims to preserve pulp vitality to allow for normal root development. Historically, calcium hydroxide has been the material of choice for pulpotomy procedures. Recently, an alternative material called mineral trioxide aggregate (MTA) has demonstrated the ability to induce hard-tissue formation in pulpal tissue. The authors describe the clinical and radiographic outcome of a series of cases involving the use of MTA in pulpotomy procedures. METHODS: Twenty-three cases in 18 patients were treated with MTA pulpotomy procedures in an endodontic private practice. All of the patients had been referred to the practice for diagnosis and treatment of a symptomatic tooth. All of the authors provided treatment. Pulpal exposures were either due to caries or complicated enamel dentin fractures. RESULTS: Nineteen teeth in 14 patients were available for recall. The mean time of recall was 19.7 months. Of the 19 cases, 15 involved healed teeth, and three involved teeth that were healing. One of 19 cases involved a tooth with persistent disease. CONCLUSIONS: MTA may be useful as a substitute for calcium hydroxide in pulpotomy procedures. Further research, however, is required to clarify this conclusion. CLINICAL IMPLICATIONS: MTA conceivably could replace calcium hydroxide as the material of choice for pulpotomy procedures, if future research continues to show promising results.


Subject(s)
Aluminum Compounds/therapeutic use , Calcium Compounds/therapeutic use , Dental Materials/therapeutic use , Dental Pulp Capping , Oxides/therapeutic use , Pulpotomy , Silicates/therapeutic use , Adolescent , Child , Dental Caries/complications , Dental Enamel/injuries , Dental Pulp/diagnostic imaging , Dental Pulp/drug effects , Dental Pulp Exposure/therapy , Dentin/injuries , Dentin, Secondary/drug effects , Drug Combinations , Follow-Up Studies , Humans , Incisor/pathology , Molar/pathology , Pulpitis/therapy , Radiography , Tooth Fractures/complications , Treatment Outcome , Wound Healing/drug effects
14.
Photosynth Res ; 87(3): 303-11, 2006 Mar.
Article in English | MEDLINE | ID: mdl-16699921

ABSTRACT

A new microcontroller-based photometric instrument for monitoring blue light dependent changes in leaf transmission (chloroplast movement) was developed based on a modification of the double-beam technique developed by Walzcak and Gabrys [(1980) Photosynthetica 14: 65-72]. A blue and red bicolor light emitting diode (LED) provided both a variable intensity blue actinic light and a low intensity red measuring beam. A phototransistor detected the intensity of the transmitted measuring light. An inexpensive microcontroller independently and precisely controlled the light emission of the bicolor LED. A typical measurement event involved turning off the blue actinic light for 100 mus to create a narrow temporal window for turning on and measuring the transmittance of the red light. The microcontroller was programmed using LogoChip Logo (http://www.wellesley.edu/Physics/Rberg/logochip/) to record fluence rate response curves. Laser scanning confocal microscopy was utilized to correlate the changes in leaf transmission with intercellular chloroplast position. In the dark, the chloroplasts in the spongy mesophyll exhibited no evident asymmetries in their distribution, however, in the palisade layer the cell surface in contact with the overlying epidermis was devoid of chloroplasts. The low light dependent decrease in leaf transmittance in dark acclimated leaves was correlated with the movement of chloroplasts within the palisade layer into the regions previously devoid of chloroplasts. Changes in leaf transmittance were evident within one minute following the onset of illumination. Minimal leaf transmittance was correlated with chloroplasts having retreated from cell surfaces perpendicular to the incident light (avoidance reaction) in both spongy and palisade layers.


Subject(s)
Chloroplasts/metabolism , Photometry/economics , Photometry/instrumentation , Arabidopsis/radiation effects , Chloroplasts/radiation effects , Darkness , Light , Movement , Plant Leaves/cytology , Plant Leaves/radiation effects , Time Factors
15.
Proc Natl Acad Sci U S A ; 99(8): 5738-43, 2002 Apr 16.
Article in English | MEDLINE | ID: mdl-11929977

ABSTRACT

The 2-cysteine peroxiredoxins (2-Cys Prx) constitute an ancient family of peroxide detoxifying enzymes and have acquired a plant-specific function in the oxygenic environment of the chloroplast. Immunocytochemical analysis and work with isolated intact chloroplasts revealed a reversible binding of the oligomeric form of 2-Cys Prx to the thylakoid membrane. The oligomeric form of the enzyme was enhanced under stress. The 2-Cys Prx has a broad substrate specificity with activity toward hydrogen peroxides and complex alkyl hydroperoxides. During the peroxide reduction reaction, 2-Cys Prx is alternatively oxidized and reduced as it catalyzes an electron flow from an electron donor to peroxide. Escherichia coli thioredoxin, but also spinach thioredoxin f and m were able to reduce oxidized 2-Cys Prx. The midpoint redox potential of -315 mV places 2-Cys Prx reduction after Calvin cycle activation and before switching the malate valve for export of excess reduction equivalents to the cytosol. Thus the 2-Cys Prx has a defined and preferential place in the hierarchy of photosynthetic electron transport. The activity of 2-Cys Prx also is linked to chloroplastic NAD(P)H metabolism as indicated by the presence of the reduced form of the enzyme after feeding dihydroxyacetone phosphate to intact chloroplasts. The function of the 2-Cys Prx is therefore not confined to its role in the water-water cycle pathway for energy dissipation in photosynthesis but also mediates peroxide detoxification in the plastids during the dark phase.


Subject(s)
Oxidation-Reduction , Peroxidases/metabolism , Peroxidases/physiology , Peroxides/metabolism , Photosynthesis , Arabidopsis Proteins , Cell Division , Chloroplasts/metabolism , Electrons , Escherichia coli/metabolism , Hordeum/physiology , Hydrogen Peroxide/metabolism , Immunohistochemistry , Kinetics , Models, Biological , Mutagenesis, Site-Directed , Oxygen/metabolism , Peroxiredoxins , Plant Proteins/metabolism , Plastids/metabolism , Protein Binding , Recombinant Proteins/metabolism , Substrate Specificity , Thioredoxins/metabolism , Thylakoids/metabolism , Time Factors
16.
Oecologia ; 104(3): 280-290, 1995 Nov.
Article in English | MEDLINE | ID: mdl-28307583

ABSTRACT

Xanthophyll-cycle pigments and photosynthetic capacity (PSmax) were analyzed in 25 species from different light environments (canopy, gap, understory) within a Panamanian tropical forest. (1) Sun-exposed leaves of canopy tree species showed the highest photosynthetic capacities and largest xanthophyll-cycle pools (violaxanthin, antheraxanthin, zeaxanthin) of about 87 mmol mol-1 chlorophyll with only small amounts of α-carotene [about 7 mmol mol-1 chlorophyll = 8% of total (α+ß) carotene pool]. Under high natural photon flux densities (PFDs) canopy leaves rapidly converted up to 96% of the xanthophyll-cycle pool into zeaxanthin. The back reaction to violaxanthin occurred much faster in low light than in complete darkness. At the end of the night, zeaxanthin still accounted for, on average, 14% of the total xanthophyll-cycle pigments. (2) Leaves of gap plants had intermediate values of PSmax and a 43% lower total carotenoid content than canopy leaves. The average size of the xanthophyll-cycle pool was 35 mmol mol-1 chlorophyll, and α-carotene accounted for up to 66% of the total (α+ß) carotene pool. Under high light conditions gap plants converted, on average, 86% of the xanthophyll-cycle pigments into zeaxanthin. The back reaction, following a decrease in ambient PFD, was slower than the forward reaction. At the end of the night, zeaxanthin accounted for, on average, 7% of the xanthophyll-cycle pigments in gap plants. (3) Understory plants showed the lowest values of PSmax and the smallest xanthophyll-cycle pool of about 22 mmol mol-1 chlorophyll. α-Carotene accounted for up to 70% of total carotene. The conversion of xanthophyll-cycle pigments into zeaxanthin was negligible during short sunflecks of 1-2 min duration and PFDs up to about 400 µmol m-2 s-1. At predawn, leaves of understory plants rarely contained any detectable zeaxanthin. Aechmea magdalenae, an understory CAM plant, showed exceptionally high rates of PSmax per unit leaf area compared to sympatric C3 understory species.

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