504 research outputs found
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
17
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]+
SANS study of dialkylsubstituted diphosphonic acids and their complexes with Ca, Fe, La, Th and U in toluene
- …