American Dreams: DACA Dreamers, Trump as a Political and Social Event, and the Performative Practice of Storytelling in the Age of Secondary Orality

In September 2017, the Trump administration announced its plan to rescind The Deferred Action for Childhood Arrivals Program (DACA). Since then, program recipients, who have in recent years assumed the name Dreamers, have fought back. This thesis explores how Dreamers use storytelling as a means of articulating individual and collective identity as a form of resistance in the sociopolitical climate that is Trump\u27s America

Reliable postprocessing improvement of van der Waals heterostructures

The successful assembly of heterostructures consisting of several layers of different 2D materials in arbitrary order by exploiting van der Waals forces has truly been a game changer in the field of low dimensional physics. For instance, the encapsulation of graphene or MoS2 between atomically flat hexagonal boron nitride (hBN) layers with strong affinity and graphitic gates that screen charge impurity disorder provided access to a plethora of interesting physical phenomena by drastically boosting the device quality. The encapsulation is accompanied by a self-cleansing effect at the interfaces. The otherwise predominant charged impurity disorder is minimized and random strain fluctuations ultimately constitute the main source of residual disorder. Despite these advances, the fabricated heterostructures still vary notably in their performance. While some achieve record mobilities, others only possess mediocre quality. Here, we report a reliable method to improve fully completed van der Waals heterostructure devices with a straightforward post-processing surface treatment based on thermal annealing and contact mode AFM. The impact is demonstrated by comparing magnetotransport measurements before and after the AFM treatment on one and the same device as well as on a larger set of treated and untreated devices to collect device statistics. Both the low temperature properties as well as the room temperature electrical characteristics, as relevant for applications, improve on average substantially. We surmise that the main beneficial effect arises from reducing nanometer scale corrugations at the interfaces, i.e. the detrimental impact of random strain fluctuations

Caracterização da vulnerabilidade do aqüifero freático na área de influência da Refinaria Alberto Pasqualini, RS

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Fotografien von Rudolf Lehnert (1878-1948). Eine Bildanalyse im kolonialen Kontext

Diese Arbeit untersucht die Bildproduktion des österreichischen Fotografen Rudolf Lehnert in Tunesien in der Zeit von 1904 bis 1914 aus kritisch-kunsthistorischer Sicht. Einem Abriss der Unternehmensgeschichte von Lehnert & Landrock sowie einem Überblick über die Rezeption des Gesamtwerkes folgen eine kurze Darstellung der Konstruktion von „Orient“ und eine Auseinandersetzung mit dem Realitätseffekt fotografischer Bilder im kolonialen Kontext. Auf dieser Basis wurden die Forschungsfragen formuliert, insbesondere Fragen zum historischen Kontext des Werkes, zum Stand der Technik und der Ausbildung des Fotografen, welche sich dieser an der K. k. Graphischen Lehr- und Versuchanstalt aneignen konnte. Weiters sind Fragen zur Kontinuität von Motiven und Strukturen der Orientdarstellung Gegenstand dieser Untersuchung. Anhand eines repräsentationskritischen Ansatzes werden Lehnerts Arbeiten aus dieser Zeit in den Kontext der Geschichte der Kolonisierung Tunesiens und der aufkommenden Tourismusindustrie gestellt. Das von ihm Fotografierte wird kritisch in Bezug zur damaligen Situation vor Ort gesetzt. Es zeigt sich, dass die koloniale Realität zugunsten eines märchenhaft imaginierten „Orients“ in seinen Fotografien konsequent ausgeblendet bleibt. Der nachvollziehbare Einfluss seiner Ausbildung wird anhand seiner Ausbildung und der ihm zur Verfügung stehenden Literatur detailliert nachgezeichnet. Die von ihm verwendete fotografische Positiv- und Negativverarbeitung, sowie sein Herangehen an Landschaftsfotografie oder „akademischen Studien“ lassen sich direkt auf seine Ausbildung zurückführen. Es zeigt sich, dass Rudolf Lehnert unter Anwendung kompromissloser Qualitätsstandards fotografierte. Der damit verbundene beträchtliche Aufwand, der für den Akt des Fotografierens betrieben wurde, bleibt in seinen Repräsentationen des kolonisierten Tunesien jedoch unsichtbar. Die Untersuchung macht deutlich, wie das Unternehmen Lehnert & Landrock im Rahmen der kolonialen Ökonomie mit modernsten Mitteln operierte. Es wird im Detail nachgewiesen, dass sich in der Motivik des Oeuvres deutliche Bezüge zur „Description de l’Egypte“ herstellen lassen. Im Überblick zeigt sich, dass es in der Mehrzahl von westlichen Eingriffen bereinigte Bilder sind, in denen das koloniale Machtgefälle implizit eingeschrieben ist – Vorstellungen vom Gegenteil des Selbstverständnisses eines modernen Europa. Die vorliegende Analyse macht auch klare Anleihen Lehnerts an der Orientmalerei sichtbar, insbesondere bei seinen Haremskonstruktionen und Wüstendarstellungen. In diesem Zusammenhang lässt sich jedoch auch ein Bruch mit den schematischen Wüstendarstellungen früherer Orientmaler feststellen. Abschließend werden die Problematik der standardisierten Visualisierung und jene der medial bedingten soziokulturellen Verschiebung thematisiert. Es wird dargelegt, wie v. a. durch die zahl- und erfolgreich vertriebenen Postkarten des kolonisierten Tunesien die Fotografien des Unternehmens L&L zur Schaffung einer Ersatzwirklichkeit im kolonialen Diskurs beitrugen

Mecanismos envolvidos na progressão do câncer de ovário : 1) papel de NAC1 e BCL6 na regulação da expressão gênica; 2) efeito da cisplatina no fenótipo de células-tronco tumorais, migração e quimiorresistência

Ovarian cancer (OVCA) is the most lethal gynecological cancer, and its dissemination and chemoresistance are major factors determining disease prognosis. Better understanding of mechanisms involved in these processes is crucial to improve OVCA therapy; therefore being the aim of the present study. Firstly, the role of NAC1 and BCL6 regulating transcription in OVCA has been investigated using FOXQ1 as a study model. It has been shown that NAC1 and BCL6 interact through NAC1’s BEN C-terminus domain, forming a complex which binds to three BCL6 binding motives on FOXQ1 promoter, activating its transcription. A positive correlation between NAC1 and BCL6 expression has been shown in OVCA cell lines and tumor specimens. Moreover, BCL6-depending NAC1 binding to BCL6 promoter activating its transcription has been shown. Therefore, a novel mechanism by which a BTB/POZ family member interacts with BCL6 attenuating its auto-repression has been herein described. Finally, cDNA microarray analyzes revealed a plethora of putative NAC1/BCL6 target genes. On the second chapter, the effects of cisplatin on OVCA progression have been analyzed. It has been shown that a five-day treatment with 10-5M cisplatin of A2780 cell increased chemoresistance, cell migration and expression of the cancer-stem cell associated phenotype CD44+CD24-, and a G2/M cell cycle arrest. The secretion of TGF-β1 and CXCL2, both cytokines involved in migration and resistance in cancer, in response to cisplatin, doxorubicin, and paclitaxel, by three cell lines originated from serous (A2780), endometrioid (MDAH-2774), and clear cell (TOV21G) OVCA subtypes has been measured. In response to cisplatin, TGF-β1 secretion by TOV21G cells has increased, as has CXCL2 secretion by TOV21G and A2780. When analyzing the effect of exogenous CXCL2 in drug resistance, this relation could not be demonstrated. However, it could be explained by CXCR2 overexpression in response to cisplatin, which has been herein demonstrated. Therefore, several different mechanisms leading to OVCA progression have been identifiedO câncer de ovário (CAOV) é a neoplasia ginecológica mais letal, sendo que a disseminação da doença e a quimiorresistência podem ser considerados fatores determinantes no prognóstico da doença. O entendimento dos mecanismos envolvidos nesses processos é essencial ao aprimoramento da terapêutica do CAOV, sendo assim o alvo de estudo deste trabalho. Primeiramente, investigou-se o papel de NAC1 e BCL6 na regulação da transcrição no CAOV, utilizando-se como modelo FOXQ1. Viu-se que NAC1 e BCL6 interagem através do domínio BEN Cterminal de NAC1, formando um complexo que se liga a motivos de ligação a BCL6 localizados na região promotora de FOXQ1 que, conforme se mostrou, possui três desses motivos. Em seguida, mostrou-se que existe uma correlação positiva entre a expressão de NAC1 e BCL6 em linhagens celulares de CAOV e em tumores. Mostrou-se ainda, que NAC1 liga-se ao promotor de BCL6 de forma dependente da proteína BCL6, ativando a sua transcrição. Dessa forma, descreveu-se de forma inédita um mecanismo através do qual um membro da família BTB/POZ interage com BCL6 atenuando a sua autorregulação negativa. Por fim, através de análise de microarranjo de cDNA identificaram-se possíveis novos alvos de regulação do complexo NAC1/BCL6. Na segunda parte deste trabalho, analisaram-se os efeitos da cisplatina na progressão do CAOV. Mostrou-se que, em resposta ao tratamento por cinco dias com cisplatina 10-5M, células da linhagem A2780 apresentaram aumento de migração, resistência e expressão do fenótipo de células-tronco tumorais CD44+CD24-; além da droga induzir uma parada do ciclo celular em fase G2/M. Também se analisou a secreção de TGF-β1 e CXCL2, citocinas envolvidas com a resistência e metástase no câncer, em resposta à cisplatina, à doxorrubicina e ao paclitaxel, em três linhagens de CAOV derivadas de tumores dos tipos seroso (A2780), endometrioide (MDAH-2774) e de células claras (TOV21G). Mostrou-se que, em resposta à cisplatina, apenas, havia o aumento da secreção de TGF-β1 por células TOV21G e de CXCL2 por células A2780 e TOV21G. Em seguida, buscou-se identificar se CXCL2 exógeno seria capaz de induzir a resistência nas células A2780. Esse efeito não foi observado. Contudo, pode ser explicado pela regulação positiva da expressão de CXCR2 induzida pela cisplatina aqui mostrada. Dessa forma, identificaram-se diferentes mecanismos que podem contribuir para a progressão do CAOVCAPE

Metal Ion Complexes of N,N′-Bis(2-Pyridylmethyl)-trans-1,2-Diaminocyclohexane-N,N′-Diacetic Acid, H2bpcd: Lanthanide(III)–bpcd2– Cationic Complexes

The synthesis and characterization of N,N′-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane-N,N′-diacetic acid (H2bpcd) cationic complexes of La(III), Nd(III), and Sm(III) are reported. The Ln(III)–bpcd2– complex ions, where bpcd2– stands for N,N′-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane-N,N′-diacetate, were isolated as PF6– salts. These salts were characterized by elemental analysis, X-ray crystallography, IR, and 1H and 13C NMR spectroscopy. Binuclear [La2(bpcd)2(H2O)2]2+ crystallized from an aqueous solution in the monoclinic P21/c space group as a cocrystallate with Na2bpcd and NaPF6, nominally Na2.34[La1.22(C22H26N4O4)2(H2O)2][PF6]2·2H2O, with a = 11.3343(6) Å, b = 17.7090(9) Å, c = 15.0567(8) Å, β = 110.632(3)°, and Z = 4 (Z′ = 2). La is eight-coordinate with distorted dodecahedral coordination geometry provided by a N4O4 donor atom set. In addition to four N atoms from the bpcd2– ligand, La’s coordination sphere includes O atoms from a water molecule and three acetate groups (one O atom from singly bound acetate and two O atoms from acetate groups that bridge the La centers). The 1H and 13C assignments for H2bpcd and the metal–bpcd2– complexes were made on the basis of 2D COSY and HSQC experiments, which established 1H–1H and 1H–13C correlations. The NMR spectral data were used to establish the symmetry of the cationic complexes present in aqueous solution. The data indicate that the La(III)–bpcd2– and Sm(III)–bpcd2– complexes are present in solution as a single species with C2 symmetry. The 1H NMR spectrum of [Nd(bpcd)]PF6 in D2O consists of eight considerably line-broadened, paramagnetic-shifted singlets. The ab initio quantum mechanical calculations at the PCM/MP2/SDD//HF/SDD level, which were established previously for determining isomerization energies for octahedral M(III)–bpad2– complex ions, were used to determine the relative free energies of the geometric isomers possible for eight- and nine-coordinate La(III)–bpcd2– cationic aqua complexes in aqueous solution, i.e., [La(bpcd)(H2O)2]+ and La(bpcd)(H2O)3]+