464 research outputs found

    Digital heritage documentation of structures at the Maya sites of Birds of Paradise - North and Tz'unun in Belize

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    Digital documentation of structures continued at Tz’unun with a brief operation at Birds of Paradise – North. The bulk of the data collected during the field season occurred during sessions 1-3 and focused on multi-image photogrammetry of excavations at Tz’unun: Structure 4 & 5 (ballcourt), Structure 9, Structure 13, Structure 20 (E-Group radial pyramid), Structure 21, Structure 22 (E-Group eastern platform), and Chultun 18-05. In session 4, all excavations at Tz’unun were laser scanned with the exception of Chultun 18-05, which had been backfilled at the close of session 2

    Xno'ha Digital Survey 2017

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    The presentation of heritage sites is critically important to the perception of historical narratives. A key goal is to help both scholars and the general public to see heritage as dynamic and living. This project explores the visualization of archaeological excavations through preservation technologies, specifically photogrammetric data. Our study focuses on a patio group at the Maya site of Xno’ha (occupation dates range from the Late Preclassic to the Terminal Classic) in northern Belize, and the current excavation and photogrammetric documentation of three structures (32, 33, and 34). Sequential photogrammetry was conducted throughout the entire stratigraphic excavation of Structure 34’s unit, resulting in 9 layers of photogrammetric documentation. The same process was applied to a chultun feature (single chamber) at Structure 33, creating 18 layers of photogrammetric data at regular intervals. For Structure 32, a single-phase, 3D model was generated, successfully stitching the above-ground unit to its corresponding, subterranean chultun (three chambers). Additionally, photogrammetry was used to create a plan view of the patio group area, and to create wall elevations. This methodical documentation of the process of excavation, in the span of months, records a three-dimensional time-lapse dialing back architectural conditions of the site hundreds of years

    Label-free optical detection of single enzyme-reactant reactions and associated conformational changes

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    Monitoring the kinetics and conformational dynamics of single enzymes is crucial in order to better understand their biological functions as these motions and structural dynamics are usually unsynchronized among the molecules. Detecting the enzyme-reactant interactions and associated conformational changes of the enzyme on a single molecule basis, however, remain as a challenge with established optical techniques due to the commonly required labeling of the reactants or the enzyme itself. The labeling process is usually non-trivial and the labels themselves might skew the physical properties of the enzyme. Here we demonstrate an optical, label-free method capable of observing enzymatic interactions and the associated conformational changes on the single molecule level. We monitor polymerase/DNA interactions via the strong near-field enhancement provided by plasmonic nanorods resonantly coupled to whispering gallery modes in microcavities. Specifically, we employ two different recognition schemes: one in which the kinetics of polymerase/DNA interactions are probed in the vicinity of DNA-functionalized nanorods, and the other in which these interactions are probed via the magnitude of conformational changes in the polymerase molecules immobilized on nanorods. In both approaches we find that low and high polymerase activities can be clearly discerned via their characteristic signal amplitude and signal length distributions. Furthermore, the thermodynamic study of the monitored interactions suggests the occurrence of DNA polymerization. This work constitutes a proof-of-concept study of enzymatic activities via plasmonically enhanced microcavities and establishes an alternative and label-free method capable of investigating structural changes in single molecules

    Optical observation of single atomic ions interacting with plasmonic nanorods in aqueous solution

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    This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordPlasmonic nanoparticles provide the basis for a multitude of applications in chemistry, health care and optics because of their unique properties. Nanoparticle-based techniques have evolved into powerful tools for studying molecular interactions with single-molecule resolution. Here we show that this sensing capability can be used to detect single atomic ions in aqueous medium. We monitored interactions of single zinc and mercury ions with plasmonic gold nanorods (NRs) resonantly coupled to our whispering gallery mode sensor. Our system's ability to discern permanent binding and transient interaction allows us to study the different interaction kinetics of both ion species. The detection of transient interactions enables us to confirm statistically that the sensor signals originate from single ions. Furthermore, we reveal how the ion–NR interactions evolve with respect to the medium's ionic strength as mercury ions amalgamate with gold and zinc ions eventually turn into probes of highly localized surface potentials.Max Planck Societ

    Digital heritage documentation of structures at the Maya sites of Birds of Paradise - North and Tz'unun in Belize

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    Digital documentation of structures continued at Tz’unun with a brief operation at Birds of Paradise – North. The bulk of the data collected during the field season occurred during sessions 1-3 and focused on multi-image photogrammetry of excavations at Tz’unun: Structure 4 & 5 (ballcourt), Structure 9, Structure 13, Structure 20 (E-Group radial pyramid), Structure 21, Structure 22 (E-Group eastern platform), and Chultun 18-05. In session 4, all excavations at Tz’unun were laser scanned with the exception of Chultun 18-05, which had been backfilled at the close of session 2

    In situ observation of single-molecule surface reactions from low to high affinities

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    This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordUnderstanding reactions occurring between ligand molecules and nanomaterial surfaces is essential in the field of nanoscience. The conventional methods for characterizing such surface-based reactions allow only for the analysis of the end product of a reaction, although the reaction path proceeds through the transient interaction of reactants and with kinetics dependent on environmental parameters. Here we study single molecule reaction kinetics associated with gold nanoparticle surfaces in an aqueous medium by utilizing whispering-gallery-mode microcavity sensors. Our approach resolves transient as well as permanent interaction kinetics of ligand molecules at the nanoparticle interface in situ, over a broad range of affinities and even under conditions where no net product is formed. This enables us to monitor and characterize reactions during the entire procedure of a bottom-up surface modification, ranging from the deposition of ligands to the confirmation of their functionality. We demonstrate this prospect by studying surface reaction kinetics with respect to the species of ligand head groups, tethered molecules, and inhibitors in addition to subsequent bio-specific reactions between tethered molecules and analytes.Max Planck Societ

    Extreme accumulation of nucleotides in simulated hydrothermal pore systems

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    We simulate molecular transport in elongated hydrothermal pore systems influenced by a thermal gradient. We find extreme accumulation of molecules in a wide variety of plugged pores. The mechanism is able to provide highly concentrated single nucleotides, suitable for operations of an RNA world at the origin of life. It is driven solely by the thermal gradient across a pore. On the one hand, the fluid is shuttled by thermal convection along the pore, whereas on the other hand, the molecules drift across the pore, driven by thermodiffusion. As a result, millimeter-sized pores accumulate even single nucleotides more than 108-fold into micrometer-sized regions. The enhanced concentration of molecules is found in the bulk water near the closed bottom end of the pore. Because the accumulation depends exponentially on the pore length and temperature difference, it is considerably robust with respect to changes in the cleft geometry and the molecular dimensions. Whereas thin pores can concentrate only long polynucleotides, thicker pores accumulate short and long polynucleotides equally well and allow various molecular compositions. This setting also provides a temperature oscillation, shown previously to exponentially replicate DNA in the protein-assisted PCR. Our results indicate that, for life to evolve, complicated active membrane transport is not required for the initial steps. We find that interlinked mineral pores in a thermal gradient provide a compelling high-concentration starting point for the molecular evolution of life

    Modulation pH-regulativer Transportproteine durch FettsÀurerezeptoren im Pansenepithel des Schafes

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    Einleitung: Ruminal werden Futterpflanzen zu kurzkettigen FettsĂ€uren (SCFAs) abgebaut. Diese bilden die Hauptenergiequelle fĂŒr den WiederkĂ€uerorganismus. Da diese FettsĂ€uren jedoch auch maßgeblich die pH-Homöostase der Vormagenschleimhaut beeinflussen, muss das Pansenepithel in der Lage sein, Änderungen im Substrat- und Protonenangebot festzustellen und anschließend regulative Prozesse anzupassen, um Stoffwechselentgleisungen und so auch einer Pansenazidose vorzubeugen. In anderen Spezies erwiesen sich sogenannte „Freie FettsĂ€urerezeptoren“ (FFARs) als potenzielle Sensoren verĂ€nderter SCFA-Mengen im Darmlumen, die u. a. durch Modulation der intrazellulĂ€ren Spiegel an zyklischem Adenosinmonophosphat (cAMP) ihre Wirkung vermitteln. Ziele der Untersuchungen: Es sollte in der vorliegenden Arbeit untersucht werden, ob FFARs im Pansenepithel des Schafes vorkommen und durch SCFAs aktiviert sowie intrazellulĂ€re Signalwege ĂŒber cAMP moduliert werden können. Im Anschluss sollte erarbeitet werden, inwiefern der nachgewiesene Einfluss von Butyrat auf die epithelialen cAMP-Spiegel Auswirkungen auf die epitheliale pH-Modulation infolge einer verĂ€nderten AktivitĂ€t von Monocarboxylattransportern (MCTs) und Na+/H+-Austauschern (NHEs) hat. Tiere, Material und Methoden: SĂ€mtliche Untersuchungen wurden an Geweben des Vormagens von Schafen (Ovis gmelini aries) durchgefĂŒhrt. Mittels Reverse-Transkriptase-Polymerase-Kettenreaktion (RT-PCR) und immunhistochemischer FĂ€rbungen wurde das Vorliegen verschiedener FFARs in nativem Pansengewebe untersucht. Zur funktionellen Charakterisierung wurden EpithelstĂŒcke aus dem ventralen Pansensack in Ussing-Kammern inkubiert und anschließend die cAMP-Spiegel im Epithel mittels einer quantitativen, kompetitiven Analyse bestimmt. Dabei wurde der Einfluss von Forskolin (ein Stimulator der cAMP-synthetisierenden Adenylylzyklasen), von Butyrat sowie von Niacin (ein FFAR-Agonist) betrachtet. Mithilfe von radioaktiv markiertem Azetat wurde der Effekt variierender cAMP-Spiegel auf die TransportaktivitĂ€t von MCTs unter Zuhilfenahme von zwei verschiedenen MCT-Hemmstoffen (CyanohydroxyzimtsĂ€ure und p-HydroxymercuribenzoesĂ€ure) in Ussing-Kammern evaluiert. Die AktivitĂ€t der NHEs wurde an kultivierten Pansenepithelzellen durch Messung des intrazellulĂ€ren pH-Wertes mittels Spektrofluorometrie unter Einfluss des NHE-Inhibitors 5-N-Ethyl-N-Isopropyl Amilorid ermittelt. Auch hierbei wurden in den Zellen unterschiedliche cAMP-Spiegel durch Forskolin-Applikation induziert. Die Daten der verschiedenen Untersuchungen wurden an 5-8 Tieren je Versuchsansatz erhoben. Die Normalverteilung wurde mittels Kolmogorov–Smirnov-Test ermittelt. Ein Friedman-Test mit anschließendem Dunn-Test wurde fĂŒr die Analyse der cAMP-Experimente genutzt. MCT und NHE Experimente wurden mithilfe einer einfachen, geblockten Varianzanalyse und anschließendem Tukey-Test ausgewertet. Ergebnisse: Die FFARs GPR109A und FFAR2 konnten an allen untersuchten Lokalisationen (Netzmagen, Pansenvorhof, dorsaler und ventraler Pansensack, Psalter) ĂŒber RT-PCR bzw. im ventralen Pansensack auch ĂŒber die immunhistochemischen FĂ€rbungen detektiert werden, wohingegen FFAR3 lediglich als mRNA im Vorhof nachweisbar war. Dies lĂ€sst die beiden Rezeptoren GPR109A und FFAR2 als mögliche Strukturen zur Detektion von SCFAs im Pansenepithel erscheinen. Die Analyse der intrazellulĂ€ren cAMP-Spiegel in Epithelien aus dem ventralen Pansensack konnte einen hemmenden Einfluss von Butyrat auf diesen Botenstoff darlegen, was auf eine Beteiligung der genannten FFARs hindeutet. Die Applikation des GPR109A-Agonisten Niacin hatte jedoch keinen Effekt auf die cAMP-Spiegel, sodass eine Wirkungsvermittlung von Butyrat ĂŒber diesen Rezeptor unwahrscheinlich scheint. Mit Blick auf die funktionellen Auswirkungen dieser cAMP-Modulation hatten variierende cAMP-Level im Kontrast zu Erkenntnissen aus Nicht-WiederkĂ€uerspezies keinen Einfluss auf die TransportaktivitĂ€t des ruminalen MCT1 unter den gewĂ€hlten in vitro-Versuchsbedingungen. Andererseits konnte die Regulation des intrazellulĂ€ren pH-Wertes von kultivierten Pansenepithelzellen tendenziell durch erhöhte cAMP-Spiegel gehemmt werden, was auf einer Hemmung von NHEs durch den second messenger beruhen könnte. Schlussfolgerungen: Die Expression von GPR109A und FFAR2 lassen diese zwei FFARs als potenzielle Sensoren der intraruminalen bzw. intraepithelialen NĂ€hrstoffkonditionen erscheinen. Dabei deuten die vorliegenden Untersuchungen auf eine Aktivierung des FFAR2 durch Butyrat und dessen Metaboliten in den basalen Schichten des Pansenepithels hin. Infolge der Rezeptoraktivierung kommt es vermutlich zu einer Verminderung der intraepithelialen cAMP-Spiegel, welche wiederum einen (schwachen) Einfluss auf die Regulation des intrazellulĂ€ren pH-Wertes mithilfe von NHEs zu haben scheinen. Entgegen unserer Ausgangshypothese scheinen aber die FFARs des ovinen Pansenepithels die pH-Homöostase des Epithels nur geringfĂŒgig zu beeinflussen. Ihre genaue physiologische Bedeutung – insbesondere des GPR109A – bleibt somit noch spekulativ.:1 Einleitung 1 2 LiteraturĂŒbersicht 3 2.1 Bedeutung kurzkettiger FettsĂ€uren fĂŒr den WiederkĂ€uer 3 2.2 Transport kurzkettiger FettsĂ€uren ĂŒber das Pansenepithel 3 2.2.1 Apikale Aufnahme in das Pansenepithel 4 2.2.2 Basolaterale Ausschleusung in den Blutstrom 6 2.3 Metabolisierung kurzkettiger FettsĂ€uren im Pansenepithel 8 2.4 pH-Homöostase 9 2.4.1 pH-Regulation des Pansenlumens 9 2.4.2 pH-Regulation des Pansenepithels 10 2.5 Anpassungsmechanismen des Pansenepithels 12 2.6 Rolle des Butyrats 15 2.7 FettsĂ€urerezeptoren 16 2.7.1 G-Protein-gekoppelte Rezeptoren 17 2.7.2 GPRs fĂŒr SCFAs 17 2.7.2.1 FFAR2 17 2.7.2.2 FFAR3 18 2.7.2.3 GPR109A 19 2.7.3 FFARs im WiederkĂ€uerorganismus 20 2.8 Monocarboxylattransporter 22 2.8.1 Die Familie der MCTs 22 2.8.2 Regulation der MCTs 23 2.8.3 MCTs im Pansenepithel 24 2.9 Natrium-Protonen-Austauscher 26 2.9.1 Die Familie der NHEs 26 2.9.2 Regulation der NHEs 27 2.9.3 NHEs im Pansenepithel 28 2.10 Fragestellungen der vorliegenden Arbeit 30 3 Publikationen 32 3.1 Publikation 1 32 3.2 Publikation 2 41 3.2.1 Supporting Information 56 4 Diskussion 57 4.1 Nachweis von FFARs im Pansenepithel 57 4.1.1 Regulation intrazellulĂ€rer Signalwege durch FFARs 59 4.1.2 GPR109A als potenzieller Butyrat-Rezeptor im Pansenepithel 62 4.1.3 FFAR2 als potenzieller Rezeptor fĂŒr Butyrat 63 4.2 SeitenabhĂ€ngigkeit der Butyrat-Effekte 64 4.3 pH-AbhĂ€ngigkeit der cAMP-Spiegel 66 4.4 Einfluss von cAMP auf die AktivitĂ€t der MCTs 68 4.5 Einfluss von cAMP auf die NHE-AktivitĂ€t 70 4.6 Schlussfolgerungen 73 5 Zusammenfassung 75 6 Summary 77 7 Literaturverzeichnis 79 8 Anhang 101 8.1 Im Rahmen dieser Dissertation gehaltene PrĂ€sentationen 101 Danksagung 103Introduction: Forage plants are ruminally degraded to short chain fatty acids (SCFAs). These serve as the main energy source for ruminants. As SCFAs also influence the pH-homeostasis of the ruminal mucosa, the epithelium must be able to detect changes of both substrate and proton accumulation and adapt transport processes accordingly, in order to prevent metabolic dysfunction and thus the risk of ruminal acidosis. Studies in non-ruminant species detected so-called ‘free fatty acid receptors’ (FFARs) as potential SCFA-sensors in the gut lumen. It has been shown that these receptors transduce their information by modulation of intracellular levels of cyclic adenosine monophosphate (cAMP). Aim: This study intended to investigate if FFARs are located in the ovine ruminal epithelium. It should further be evaluated if FFARs can be stimulated by SCFAs leading to a modulation of intracellular pathways via cAMP. Finally, the study aimed to elucidate the influence of low epithelial cAMP-levels after butyrate application on the regulation of pH-homeostasis in the ruminal epithelium by modulating the activity of transport proteins such as monocarboxylate transporters (MCTs) and Na+/H+ exchangers (NHEs). Animals, material, and methods: All experiments were conducted with ovine (Ovis aries) ruminal tissues. The expression of different FFARs was investigated in native tissues using a reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemical staining. For functional analysis, epithelial cAMP levels were determined by a quantitative and competitive assay after incubation of epithelia of the ruminal ventral sac in Ussing chambers. The influence of forskolin (a stimulator of the adenylyl cyclases), butyrate, as well as niacin (an FFAR agonist) was evaluated. Further, the effect of varying cAMP levels on transport activity of MCTs was characterised on Ussing chamber-mounted epithelia with radioactively labelled acetate and two MCT inhibitors (cyano-hydroxycinnamic acid and p-hydroxymercuribenzoic acid). Finally, the activity of NHEs was assessed in cultured ruminal epithelial cells. The intracellular pH was evaluated by spectrofluorometry while the cells were incubated with forskolin (to modify intracellular cAMP levels) or the NHE inhibitor 5-(N-ethyl-N-isopropyl)-amiloride. The data for the different set-ups were acquired from 5-8 animals each. Kolmogorov–Smirnov test was used for testing normality. For cAMP level analyses, the Friedman test followed by Dunn's test was performed. MCT and NHE measurements were analysed using one-way randomized block analysis of variance followed by Tukey's test. Results: GPR109A and FFAR2 were detected in all ovine ruminal epithelia examined (reticulum, atrium ruminis, ruminal ventral and dorsal sac, omasum) by RT-PCR and in ruminal ventral sac also by immunohistochemical staining. FFAR3, however, was detected solely on mRNA level in tissues of the ovine atrium ruminis. Thus, the two immunohistochemically detected receptors may serve as potential sensors for SCFAs in the ruminal epithelium. The analysis of intraepithelial cAMP levels revealed an inhibiting influence of butyrate application on cAMP pointing to an activation of FFARs by this SCFA. Nonetheless, the incubation with the GPR109A agonist niacin did not show any effect on cAMP levels. This finding contradicts the theory of an activation of GPR109A by butyrate. Looking at functional consequences of varying cAMP levels, in contrast to studies on non-ruminant species ruminal MCT1 activity was not influenced by different cAMP levels, at least under the conditions chosen in this in vitro study. However, regulation of intracellular pH in cultured ruminal epithelial cells tended to decrease with augmented cAMP levels. This might be mediated by an inhibition of NHEs. Conclusions: The expression of GPR109A and FFAR2 points at a participation of these receptors in sensing intraruminal and intraepithelial energy status. The present data hint at an activation of FFAR2 by butyrate or its metabolites in the basal layers of the epithelium. Activation of the receptor leads to decreased cAMP levels. This in turn seems to slightly modify the regulation of intracellular pH via NHEs. Contradicting our initial hypothesis, ovine ruminal FFARs seem to play only a minor role in modulation of epithelial pH homeostasis. The main physiological role of ruminal FFARs – especially of GPR109A – remains to be clarified.:1 Einleitung 1 2 LiteraturĂŒbersicht 3 2.1 Bedeutung kurzkettiger FettsĂ€uren fĂŒr den WiederkĂ€uer 3 2.2 Transport kurzkettiger FettsĂ€uren ĂŒber das Pansenepithel 3 2.2.1 Apikale Aufnahme in das Pansenepithel 4 2.2.2 Basolaterale Ausschleusung in den Blutstrom 6 2.3 Metabolisierung kurzkettiger FettsĂ€uren im Pansenepithel 8 2.4 pH-Homöostase 9 2.4.1 pH-Regulation des Pansenlumens 9 2.4.2 pH-Regulation des Pansenepithels 10 2.5 Anpassungsmechanismen des Pansenepithels 12 2.6 Rolle des Butyrats 15 2.7 FettsĂ€urerezeptoren 16 2.7.1 G-Protein-gekoppelte Rezeptoren 17 2.7.2 GPRs fĂŒr SCFAs 17 2.7.2.1 FFAR2 17 2.7.2.2 FFAR3 18 2.7.2.3 GPR109A 19 2.7.3 FFARs im WiederkĂ€uerorganismus 20 2.8 Monocarboxylattransporter 22 2.8.1 Die Familie der MCTs 22 2.8.2 Regulation der MCTs 23 2.8.3 MCTs im Pansenepithel 24 2.9 Natrium-Protonen-Austauscher 26 2.9.1 Die Familie der NHEs 26 2.9.2 Regulation der NHEs 27 2.9.3 NHEs im Pansenepithel 28 2.10 Fragestellungen der vorliegenden Arbeit 30 3 Publikationen 32 3.1 Publikation 1 32 3.2 Publikation 2 41 3.2.1 Supporting Information 56 4 Diskussion 57 4.1 Nachweis von FFARs im Pansenepithel 57 4.1.1 Regulation intrazellulĂ€rer Signalwege durch FFARs 59 4.1.2 GPR109A als potenzieller Butyrat-Rezeptor im Pansenepithel 62 4.1.3 FFAR2 als potenzieller Rezeptor fĂŒr Butyrat 63 4.2 SeitenabhĂ€ngigkeit der Butyrat-Effekte 64 4.3 pH-AbhĂ€ngigkeit der cAMP-Spiegel 66 4.4 Einfluss von cAMP auf die AktivitĂ€t der MCTs 68 4.5 Einfluss von cAMP auf die NHE-AktivitĂ€t 70 4.6 Schlussfolgerungen 73 5 Zusammenfassung 75 6 Summary 77 7 Literaturverzeichnis 79 8 Anhang 101 8.1 Im Rahmen dieser Dissertation gehaltene PrĂ€sentationen 101 Danksagung 10

    Change of Venue: An Exploratory, Multistage Evaluation that Examines the Impact of Change Based on the Shared Experiences of the Toe Tag Monologues

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    This study determined how Vision Theatrical Foundation addresses the needs of troubled and traumatized local youth. I wanted to see if their services and interventions had an impact and if that impact resulted in a change and/or an improved quality of their lives. In addition, I wanted to see if the impact improved mental health literacy. This is a mixed-method, convergent, multistage, process and impact evaluation. An exploratory process evaluation was conducted on the organization utilizing SAMHSA’s Process Evaluation to Monitor Program Implementation (SAMHSA, 2018), which assesses five key questions about the program. The strengths and weaknesses of the organization were identified. The Toe Tag Impact Scale was used to survey participants regarding their attitudes and beliefs about the services and interventions provided by the organization. The variables were impact and change. There was a moderate positive correlation between the variables, r = .638, n = 18, p = .004, and the ANOVA indicated a statistical significance at F(1,17) [MSE = .227, n2 = .371], p = .004. A content analysis and an intensive analysis was conducted on essays written by youth who had previously received services. The results showed that youth identified attitudes and beliefs that corresponded with the conceptual framework of Jorm et al (1997), Components of Mental Health Literacy. These components were integrated with the theoretical framework from the Transtheoretical Model of Change (Prochaska & Velicer, 1997). Vision Theatrical Foundation can implement services and interventions that can meet the needs of at-risk youth and juvenile offenders
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