Lost-and-found Photos: Practices and Perceptions

Personal photographs become separated from their original owners in a number of ways, due to time or tragedy, sometimes ending up in strangers’ hands. Dealers, collectors, curators, bloggers, scholars, and families actively seek what are frequently called “orphaned,” “abandoned,” or “found” photos and present them to the public in multiple formats. This dissertation offers an analysis of the practices and perceptions that surround these presentations, and it argues for use of a more inclusive term (“lost-and-found”) to describe personal photos that are connected to both finders and losers. Data were collected in three primary ways: (1) examination of the current contexts in which “lost” photos appear (e.g. books, websites, newspapers), (2) interviews with collectors of “lost” photos, and (3) the project’s website, designed to collect anecdotes from those affected by “lost” photos. Dominating this field of study are the perspectives of those who find personal photographs. The choices photo-finders make regarding the presentation and interpretation of photographs differ in clear ways, enabling me to group their practices within five categories which are evident across all formats examined in this study: Museum Curator, Archivist/Preservationist, Essayist/Editor, Reuniter, and Dealer. What unites practitioners across these discrete categories is the act of compiling and displaying “lost” photos within public archives, where new presentations of old photos invite myriad interpretations, conversations, and possibilities. Since the perspectives of those who have lost personal photographs have been largely missing from this field of study, I created tools to capture the viewpoints of photo “losers.” The project’s website, Lostandfoundphotos.org, provided a space in which contributors shared stories of personal photos they had lost, challenging notions of finder-collectors who often see themselves as the sole appreciators of “lost” photos’ true value. Most importantly, this project gave a literal voice to photo-losers through an audio component—a voicemail system which recorded contributors’ stories of lost personal photographs. This aural element offers a new medium for the examination of the visual, and it provides an emotional depth which, it is hoped, may inspire an enlargement of lost-and-found photography practices to accommodate the perspectives of both finders and losers

Temperature Response of 129 Xe Depolarization Transfer and Its Application for Ultrasensitive NMR Detection

Trapping xenon in functionalized cryptophane cages makes the sensitivity of hyperpolarized (HP) 129Xe available for specific NMR detection of biomolecules. Here, we study the signal transfer onto a reservoir of unbound HP xenon by gating the residence time of the nuclei in the cage through the temperature-dependant exchange rate. Temperature changes larger than ∼0.6  K are detectable as an altered reservoir signal. The temperature response is adjustable with lower concentrations of caged xenon providing more sensitivity at higher temperatures. Ultrasensitive detection of functionalized cryptophane at 310 K is demonstrated with a concentration of 10 nM, corresponding to a ∼4000−fold sensitivity enhancement compared to conventional detection. This makes HPNMR capable of detecting such constructs in concentrations far below the detection limit of benchtop uv-visible light absorbance

NMR structure of the N-terminal domain of the replication initiator protein DnaA

DnaA is an essential component in the initiation of bacterial chromosomal replication. DnaA binds to a series of 9 base pair repeats leading to oligomerization, recruitment of the DnaBC helicase, and the assembly of the replication fork machinery. The structure of the N-terminal domain (residues 1-100) of DnaA from Mycoplasma genitalium was determined by NMR spectroscopy. The backbone r.m.s.d. for the first 86 residues was 0.6 +/- 0.2 Angstrom based on 742 NOE, 50 hydrogen bond, 46 backbone angle, and 88 residual dipolar coupling restraints. Ultracentrifugation studies revealed that the domain is monomeric in solution. Features on the protein surface include a hydrophobic cleft flanked by several negative residues on one side, and positive residues on the other. A negatively charged ridge is present on the opposite face of the protein. These surfaces may be important sites of interaction with other proteins involved in the replication process. Together, the structure and NMR assignments should facilitate the design of new experiments to probe the protein-protein interactions essential for the initiation of DNA replication

The antigenicity and cholesteroid nature of mycolic acids determined by recombinant chicken antibodies

<div><p>Mycolic acids (MA) are major, species-specific lipid components of Mycobacteria and related genera. In <i>Mycobacterium tuberculosis</i>, it is made up of alpha-, methoxy- and keto-MA, each with specific biological functions and conformational characteristics. Antibodies in tuberculosis (TB) patient sera respond differently towards the three MA classes and were reported to cross-react with cholesterol. To understand the antigenicity and cholesterol cross-reactivity of MA, we generated three different chicken -derived phage-displayed single-chain variable fragments (scFv) that reacted similarly towards the natural mixture of MA, but the first recognized all three classes of chemically synthetic MAs, the second only the two oxygenated types of MAs and the third only methoxy MA. The cholesterol cross-reactivity was investigated after grafting each of the three scFv types onto two configurations of constant chain domains–CH1-4 and CH2-4. Weak but significant cross-reactivity with cholesterol was found only with CH2-4 versions, notably those two that were also able to recognize the <i>trans</i>-keto MA. The cholesteroid nature of mycobacterial mycolic acids therefore seems to be determined by the <i>trans</i>-keto MA subclass. The significantly weaker binding to cholesterol in comparison to MA confirms the potential TB diagnostic application of these antibodies.</p></div

Timing of deformation in the Sarandí del Yí Shear Zone, Uruguay: implications for the amalgamation of western Gondwana during the Neoproterozoic Brasiliano-Pan-African Orogeny

U-Pb and Hf zircon (sensitive high-resolution ion microprobe -SHRIMP- and laser ablation-inductively coupled plasma-mass spectrometry -LA-ICP-MS-), Ar/Ar hornblende and muscovite, and Rb-Sr whole rock-muscovite isochron data from the mylonites of the Sarandí del Yí Shear Zone, Uruguay, were obtained in order to assess the tectonothermal evolution of this crustal-scale structure. Integration of these results with available kinematic, structural, and microstructural data of the shear zone as well as with geochronological data from the adjacent blocks allowed to constrain the onset of deformation along the shear zone at 630-625 Ma during the collision of the Nico Pérez Terrane and the Río de la Plata Craton. The shear zone underwent dextral shearing up to 596 Ma under upper to middle amphibolite facies conditions, which was succeeded by sinistral shearing under lower amphibolite to upper greenschist facies conditions until at least 584 Ma. After emplacement of the Cerro Caperuza granite at 570 Ma, the shear zone underwent only cataclastic deformation between the late Ediacaran and the Cambrian. The Sarandí del Yí Shear Zone is thus related to the syncollisional to postcollisional evolution of the amalgamation of the Río de la Plata Craton and the Nico Pérez Terrane. Furthermore, the obtained data reveal that strain partitioning and localization with time, magmatism emplacement, and fluid circulation are key processes affecting the isotopic systems in mylonitic belts, revealing the complexity in assessing the age of deformation of long-lived shear zone

Actividad de fluidos hidrotermales del Neoproterozoico tardío en el cinturón de Tandilia, Argentina

In the Barker - Villa Cacique area, Tandilia belt, alteration mineral assemblages were studied by petrography, XRD and EMPA at three different stratigraphic levels: (1) a phyllic alteration at the unconformity palaeoproterozoic basement-neoproterozoic sedimentary succession (TLPU); (2) an advanced argillic alteration in the Las Águilas Formation (middle level); and (3) a phyllic alteration on pyroclastic rocks of the Olavarría Formation (upper level). Special emphasize was placed on the chemical characterization of K-white micas and chlorites. Secondary K-white micas of altered migmatites, from the Las Aguilas and Olavarría Formations have a low paragonite content (Na* 9.5 km) for the entire sedimentary pile. Hot fluids would rise from deep-seated realms, metamorphic and/or hidden igneous sources. A correlation with a rasiliano thermo-tectonic event is hypothesized.En el área de Barker - Villa Cacique, Tandilia, se estudiaron mediante petrografía, DRX, y microsonda electrónica, las para- génesis de minerales de alteración de tres niveles estratigráficos diferentes: (1) alteración fílica de la discordancia basamento paleoproterozoico-secuencia sedimentaria neoproterozoica (TLPU); (2) alteración argílica avanzada en la Formación Las Águilas (nivel medio); y (3) alteración fílica en rocas piroclásticas de la Formación Olavarría (nivel superior). Las micas potási- cas y cloritas, de dichos niveles de alteración, fueron caracterizadas químicamente. Las micas potásicas de migmatitas alteradas y de las formaciones Las Águilas y Olavarría tienen un bajo contenido en paragonita (Na* 9,5 km) para el total de la pila sedimentaria. Los fluidos hidrotermales habrían ascendido desde ambientes profundos con una fuente metamórfica y/o cuerpos ígneos ocultos. Una correlación con un evento termo-tectónico Brasiliano es hipotetizada.Fil: Martinez, Juan Cruz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Geológico del Sur; Argentina. Universidad Nacional del Sur; ArgentinaFil: Dristas, Jorge A.. Universidad Nacional del Sur. Departamento de Geologia. Catedra de Petrologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Geológico del Sur; ArgentinaFil: Van Den Kerkhof, Alfons M. . Geowissenschaftliches Zentrum der Universität Göttingen; AlemaniaFil: Wemmer, Klaus . Geowissenschaftliches Zentrum der Universität Göttingen; AlemaniaFil: Massonne, Hans J.. Universität Stuttgart; AlemaniaFil: Theye, Thomas. Universität Stuttgart; AlemaniaFil: Frisicale, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Geológico del Sur; Argentina. Universidad Nacional del Sur; Argentin

Structural analysis of covalent peptide dimers, bis(pyridine-2-carboxamidonetropsin)(CH_2)_(3-6), in complex with 5'-TGACT-3' sites by two-dimensional NMR

The peptide pyridine-2-carboxamidonetropsin (2-PyN) binds specifically in the minor groove of 5'-(A,T)G(A,T)C(A,T)-3' sequences as a side-by-side antiparallel dimer. Tethering two 2-PyN ligands through the nitrogens of the central pyrrole rings with propyl, butyl, pentyl and hexyl linkers affords covalent peptide dimers, bis(pyridine-2-carboxamide-netropsin)(CH_2)_(3-6), which bind in the minor groove of DNA with increased binding affinities and improved sequence specificities. Two-dimensional NMR studies of the complexes formed upon binding of these covalent peptide dimers to an oligonucleotide containing a 5'-TGACT-3' site reveal that the dimeric peptides bind as intramolecular dimers with nearly identical geometry and peptide-DNA contacts as in the (2-PyN)_2•5'-TGACT-3' complex

A glimpse of a possible amyloidogenic intermediate of transthyretin

Studies have indicated that partially unfolded states occur under conditions that favor amyloid formation by transthyretin (TTR), as well as other amyloidogenic proteins. In this study, we used hydrogen exchange measurements to show that there is selective destabilization of one half of the beta-sandwich structure of TTR under such conditions. This provides more direct information about conformational fluctuations than previously available, and will facilitate design of future experiments to probe the intermediates critical to amyloid formation

Sensitivity Enhancement by Exchange Mediated MagnetizationTransfer of the Xenon Biosensor Signal

Hyperpolarized xenon associated with ligand derivitized cryptophane-A cages has been developed as a NMR based biosensor. To optimize the detection sensitivity we describe use of xenon exchange between the caged and bulk dissolved xenon as an effective signal amplifier. This approach, somewhat analogous to 'remote detection' described recently, uses the chemical exchange to repeatedly transfer spectroscopic information from caged to bulk xenon, effectively integrating the caged signal. After an optimized integration period, the signal is read out by observation of the bulk magnetization. The spectrum of the caged xenon is reconstructed through use of a variable evolution period before transfer and Fourier analysis of the bulk signal as a function of the evolution time

Temperature-controlled molecular depolarization gates in nuclear magnetic resonance

Down the drain: Cryptophane cages in combination with selective radiofrequency spin labeling can be used as molecular 'transpletor' units for transferring depletion of spin polarization from a hyperpolarized 'source' spin ensemble to a 'drain' ensemble. The flow of nuclei through the gate is adjustable by the ambient temperature, thereby enabling controlled consumption of hyperpolarization