570 research outputs found
Arraché au feu : le sauvetage du patrimoine culturel juif de Wilna
L’article de David Fishman, d’abord paru en 1996 dans une version bilingue yiddish-anglais sous les auspices du YIVO, a été ensuite traduit du yiddish et publié en allemand dans une édition bilingue par Maria Kühn- Ludewig pour le périodique professionnel indépendant Laurentius. (« Dem Feuer entrissen : die Rettung jüdischer Kulturschätze in Wilna », David E. Fishman. Hannover, Laurentius, 1998. 50 p. ISBN 3-931614-97-2). Son auteur est chercheur associé au YIVO de New York et au Jewish Theological Seminary of America . Il a publié Russia first modern Jews : the Jews of Shklov (New York University Press, 1996. ISBN 0814726607), une histoire de la communauté de Shklov (aujourd’hui en Biélorussie). Après le témoignage de Dina Abramowicz sur la bibliothèque du ghetto de Wilna publié dans le numéro 4 (octobre 2002) de BIBLIOthèque(s) et l’article de Kornelia Richter sur la lecture à Terezin publié dans le numéro 5/6, cette étude sur la tentative de sauvegarde du patrimoine juif de Wilna clôt la série d’articles consacrée aux bibliothèques et à la lecture dans les camps et dans les ghettos. La suite et fin du texte de David Fishman paraîtra dans le numéro 8 d’avril 2003. L’étude montre un autre aspect de l’extrême valorisation de la lecture et de l’écrit dans la société juive d’Europe orientale au début du XXe siècle, celui de la constitution et de la préservation du patrimoine, et éclaire dans le détail la dimension culturelle de la spoliation systématique opérée par les Allemands
Investigating prostate cancer tumour-stroma interactions - clinical and biological insights from an evolutionary game
BACKGROUND: Tumours are made up of a mixed population of different types of cells that include normal structures as well as ones associated with the malignancy, and there are multiple interactions between the malignant cells and the local microenvironment. These intercellular interactions, modulated by the microenvironment, effect tumour progression and represent a largely under appreciated therapeutic target. We use observations of primary tumor biology from prostate cancer to extrapolate a mathematical model: specifically; it has been observed that in prostate cancer three disparate cellular outcomes predominate: (i) the tumour remains well differentiated and clinically indolent - in this case the local stromal cells may act to restrain the growth of the cancer; (ii) early in its genesis the tumour acquires a highly malignant phenotype, growing rapidly and displacing the original stromal population (often referred to as small cell prostate cancer) - these less common aggressive tumours are relatively independent of the local microenvironment; and, (iii) the tumour co-opts the local stroma - taking on a classic stromagenic phenotype where interactions with the local microenvironment are critical to the cancer growth. METHODS: We present an evolutionary game theoretical construct that models the influence of tumour-stroma interactions in driving these outcomes. We consider three characteristic and distinct cellular populations: stromal cells, tumour cells that are self-reliant in terms of microenvironmental factors and tumour cells that depend on the environment for resources but can also co-opt stroma. 
RESULTS: Using evolutionary game theory we explore a number of different scenarios that elucidate the impact of tumour-stromal interactions on the dynamics of prostate cancer growth and progression and how different treatments in the metastatic setting can affect different types of tumors.
CONCLUSIONS: The tumour microenvironment plays a crucial role selecting the traits of the tumour cells that will determine prostate cancer progression. Equally important, treatments like hormone therapy affect the selection of these cancer phenotypes making it very important to understand how they impact prostate cancer’s somatic evolution
Arraché au feu : le sauvetage du patrimoine culturel juif de Wilna (fin)
L’étude de David Fishman, d’abord parue en 1996 dans une version bilingue yiddish-anglais sous les auspices du YIVO, a été ensuite traduite du yiddish et publiée en allemand dans une édition bilingue par Maria Kühn-Ludewig pour le périodique professionnel indépendant Laurentius. («Dem Feuer entrissen : die Rettung jüdischer Kulturschätze in Wilna», David E. Fishman. Hannover, Laurentius, 1998. 50 p. ISBN 3-931614-97-2). Son auteur est chercheur associé au YIVO de New York et au Jewish Theological Seminary of America. Il a publié Russia First Modern Jews : the Jews of Shklov (New York University Press, 1996. ISBN 0814726607) une histoire de la communauté de Shklov (aujourd’hui en Biélorussie). Cet article constitue la seconde et dernière partie de la publication de la traduction depuis la version allemande dont le début a été publié sous le titre Arraché au feu : le sauvetage du patrimoine culturel juif de Wilna dans le N° 7 de BIBLIOthèque(s), février 2003, pp. 59-64. La première partie relatait les entreprises de sauvetage et de dissimulation des documents du patrimoine juif confisqués par les Allemands et confiés par ceux-ci au travail de détenus juifs du ghetto de Wilna, la « brigade de papier ». Le travail clandestin de la brigade de papier prend fin en septembre 1943, à la liquidation du ghetto. Cette seconde partie traite de l’histoire des collections, de la libération de Wilna par l’Armée rouge en juillet 1944 jusqu’à nos jours, puisqu’une filière clandestine d’expédition des collections vers le YIVO de New York fonctionna tant bien que mal pendant l’époque soviétique, avant que des restitutions officielles de la part d’autorités et d’institutions lituaniennes achèvent, dans les années 1990, le rassemblement des collections épargnées à l’Institut d’études yiddish (YIVO) de New York. La coupure est de notre fait et la notation est continue depuis le début de la publication
Multimodal Imaging of Photoreceptor Structure in Choroideremia
Purpose
Choroideremia is a progressive X-linked recessive dystrophy, characterized by degeneration of the retinal pigment epithelium (RPE), choroid, choriocapillaris, and photoreceptors. We examined photoreceptor structure in a series of subjects with choroideremia with particular attention to areas bordering atrophic lesions. Methods
Twelve males with clinically-diagnosed choroideremia and confirmed hemizygous mutations in the CHM gene were examined. High-resolution images of the retina were obtained using spectral domain optical coherence tomography (SD-OCT) and both confocal and non-confocal split-detector adaptive optics scanning light ophthalmoscope (AOSLO) techniques. Results
Eleven CHM gene mutations (3 novel) were identified; three subjects had the same mutation and one subject had two mutations. SD-OCT findings included interdigitation zone (IZ) attenuation or loss in 10/12 subjects, often in areas with intact ellipsoid zones; RPE thinning in all subjects; interlaminar bridges in the imaged areas of 10/12 subjects; and outer retinal tubulations (ORTs) in 10/12 subjects. Only split-detector AOSLO could reliably resolve cones near lesion borders, and such cones were abnormally heterogeneous in morphology, diameter and density. On split-detector imaging, the cone mosaic terminated sharply at lesion borders in 5/5 cases examined. Split-detector imaging detected remnant cone inner segments within ORTs, which were generally contiguous with a central patch of preserved retina. Conclusions
Early IZ dropout and RPE thinning on SD-OCT are consistent with previously published results. Evidence of remnant cone inner segments within ORTs and the continuity of the ORTs with preserved retina suggests that these may represent an intermediate state of retinal degeneration prior to complete atrophy. Taken together, these results supports a model of choroideremia in which the RPE degenerates before photoreceptors
Photon emission correlation spectroscopy as an analytical tool for quantum defects
Photon emission correlation spectroscopy has a long history in the study of
atoms, molecules, and, more recently, solid-state quantum defects. In
solid-state systems, its most common use is as an indicator of single-photon
emission, a key property for quantum technology. However, photon correlation
data can provide a wealth of information about quantum emitters beyond their
single-photon purityinformation that can reveal details about an
emitter's electronic structure and optical dynamics that are hidden by other
spectroscopy techniques. We present a standardized framework for using photon
emission correlation spectroscopy to study quantum emitters, including
discussion of theory, data acquisition, analysis, and interpretation. We
highlight nuances and best practices regarding the commonly-used
test for single-photon emission. Finally, we illustrate
how this experimental technique can be paired with optical dynamics simulations
to formulate an electronic model for unknown quantum emitters, enabling the
design of quantum control protocols and assessment of their suitability for
quantum information science applications.Comment: 20 pages, 7 figures. Updates in version 2 include an expanded section
VI and the addition of two figures and an appendi
The Effect of Cone Opsin Mutations on Retinal Structure and the Integrity of the Photoreceptor Mosaic
Purpose.
To evaluate retinal structure and photoreceptor mosaic integrity in subjects with OPN1LW and OPN1MW mutations.
Methods.
Eleven subjects were recruited, eight of whom have been previously described. Cone and rod density was measured using images of the photoreceptor mosaic obtained from an adaptive optics scanning light ophthalmoscope (AOSLO). Total retinal thickness, inner retinal thickness, and outer nuclear layer plus Henle fiber layer (ONL+HFL) thickness were measured using cross-sectional spectral-domain optical coherence tomography (SD-OCT) images. Molecular genetic analyses were performed to characterize the OPN1LW/OPN1MW gene array.
Results.
While disruptions in retinal lamination and cone mosaic structure were observed in all subjects, genotype-specific differences were also observed. For example, subjects with “L/M interchange” mutations resulting from intermixing of ancestral OPN1LW and OPN1MW genes had significant residual cone structure in the parafovea (∼25% of normal), despite widespread retinal disruption that included a large foveal lesion and thinning of the parafoveal inner retina. These subjects also reported a later-onset, progressive loss of visual function. In contrast, subjects with the C203R missense mutation presented with congenital blue cone monochromacy, with retinal lamination defects being restricted to the ONL+HFL and the degree of residual cone structure (8% of normal) being consistent with that expected for the S-cone submosaic.
Conclusions.
The photoreceptor phenotype associated with OPN1LW and OPN1MW mutations is highly variable. These findings have implications for the potential restoration of visual function in subjects with opsin mutations. Our study highlights the importance of high-resolution phenotyping to characterize cellular structure in inherited retinal disease; such information will be critical for selecting patients most likely to respond to therapeutic intervention and for establishing a baseline for evaluating treatment efficacy
Dynamical Characterization and Room-Temperature Control of an Optically Addressable Single Spin in Hexagonal Boron Nitride
Hexagonal boron nitride (h-BN), a wide bandgap, two-dimensional solid-state
material, hosts pure single-photon emitters that have shown signatures of
optically-addressable electronic spins. Here, we report on a single emitter in
h-BN exhibiting optically detected magnetic resonance at room temperature, and
we propose a model for its electronic structure and optical dynamics. Using
photon emission correlation spectroscopy in conjunction with time-domain
optical and microwave experiments, we establish key features of the emitter's
electronic structure. Specifically, we propose a model that includes a spinless
optical ground and excited state, a metastable spin-1/2 configuration, and an
emission modulation mechanism. Using optical and spin dynamics simulations, we
constrain and quantify transition rates in the model, and we design protocols
that optimize the signal-to-noise ratio for spin readout. This constitutes a
necessary step toward quantum control of spin states in h-BN.Comment: 14 pages, 15 figures. arXiv admin note: text overlap with
arXiv:2201.0888
Probing the Optical Dynamics of Quantum Emitters in Hexagonal Boron Nitride
Hexagonal boron nitride is a van der Waals material that hosts
visible-wavelength quantum emitters at room temperature. However, experimental
identification of the quantum emitters' electronic structure is lacking, and
key details of their charge and spin properties remain unknown. Here, we probe
the optical dynamics of quantum emitters in hexagonal boron nitride using
photon emission correlation spectroscopy. Several quantum emitters exhibit
ideal single-photon emission with noise-limited photon antibunching,
. The photoluminescence emission lineshapes are consistent with
individual vibronic transitions. However, polarization-resolved excitation and
emission suggests the role of multiple optical transitions, and photon emission
correlation spectroscopy reveals complicated optical dynamics associated with
excitation and relaxation through multiple electronic excited states. We
compare the experimental results to quantitative optical dynamics simulations,
develop electronic structure models that are consistent with the observations,
and discuss the results in the context of ab initio theoretical calculations.Comment: 31 pages, 16 figures, 6 table
In Situ Probes of the First Galaxies and Reionization: Gamma-ray Bursts
The first structures in the Universe formed at z>7, at higher redshift than
all currently known galaxies. Since GRBs are brighter than other cosmological
sources at high redshift and exhibit simple power-law afterglow spectra that is
ideal for absorption studies, they serve as powerful tools for studying the
early universe. New facilities planned for the coming decade will be able to
obtain a large sample of high-redshift GRBs. Such a sample would constrain the
nature of the first stars, galaxies, and the reionization history of the
Universe.Comment: 8 pages, 3 figures, science white paper submitted to the US Astro2010
Decadal Surve
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