1,768 research outputs found
Materialism’s Affective Appeal
Citing the pronounced lack of academic engagement with Middlesex since its publication and riffing on the novel’s recounting of the demise of the auto industry in Detroit, Mazzolini examines how cycles of obsolescence and currency work within academic discourse and ultimately advocates for the novel’s potential for examining the material and affective nature of relevance itself
Towards smooth (010) beta-Ga2O3 films homoepitaxially grown by plasma assisted molecular beam epitaxy: The impact of substrate offcut and metal-to-oxygen flux ratio
Smooth interfaces and surfaces are beneficial for most (opto)electronic
devices based on thin films and their heterostructures. For example, smoother
interfaces in (010) beta-Ga2O3/(AlxGa1-x)2O3 heterostructures, whose roughness
is ruled by that of the Ga2O3 layer, can enable higher mobility 2DEGs by
reducing interface roughness scattering. To this end we experimentally prove
that a substrate offcut along the [001] direction allows to obtain smooth
beta-Ga2O3 layers in (010)-homoepitaxy under metal-rich conditions. Applying
In-mediated metal-exchange catalysis (MEXCAT) in molecular beam epitaxy at high
substrate temperatures (Tg = 900 {\deg}C) we compare the morphology of layers
grown on (010)-oriented substrates with different unintentional offcuts. The
layer roughness is generally ruled by (i) (110) and (-110)-facets visible as
elongated features along the [001] direction (rms < 0.5 nm), and (ii) trenches
(5-10 nm deep) orthogonal to [001]. We show that an unintentional substrate
offcut of only 0.1{\deg} almost oriented along the [001] direction suppresses
these trenches resulting in a smooth morphology with a roughness exclusively
determined by the facets, i.e., rms 0.2 nm. Since we found the facet-and-trench
morphology in layers grown by MBE with and without MEXCAT, we propose that the
general growth mechanism for (010)-homoepitaxy is ruled by island growth whose
coalescence results in the formation of the trenches. The presence of a
substrate offcut in the [001] direction can allow for step-flow growth or
island nucleation at the step edges, which prevents the formation of trenches.
Moreover, we give experimental evidence for a decreasing surface diffusion
length or increasing nucleation density with decreasing metal-to-oxygen flux
ratio. Based on our results we can rule-out step bunching as cause of the
trench formation as well as a surfactant-effect of indium during MEXCAT
Statistics of shared components in complex component systems
Many complex systems are modular. Such systems can be represented as
"component systems", i.e., sets of elementary components, such as LEGO bricks
in LEGO sets. The bricks found in a LEGO set reflect a target architecture,
which can be built following a set-specific list of instructions. In other
component systems, instead, the underlying functional design and constraints
are not obvious a priori, and their detection is often a challenge of both
scientific and practical importance, requiring a clear understanding of
component statistics. Importantly, some quantitative invariants appear to be
common to many component systems, most notably a common broad distribution of
component abundances, which often resembles the well-known Zipf's law. Such
"laws" affect in a general and non-trivial way the component statistics,
potentially hindering the identification of system-specific functional
constraints or generative processes. Here, we specifically focus on the
statistics of shared components, i.e., the distribution of the number of
components shared by different system-realizations, such as the common bricks
found in different LEGO sets. To account for the effects of component
heterogeneity, we consider a simple null model, which builds
system-realizations by random draws from a universe of possible components.
Under general assumptions on abundance heterogeneity, we provide analytical
estimates of component occurrence, which quantify exhaustively the statistics
of shared components. Surprisingly, this simple null model can positively
explain important features of empirical component-occurrence distributions
obtained from data on bacterial genomes, LEGO sets, and book chapters. Specific
architectural features and functional constraints can be detected from
occurrence patterns as deviations from these null predictions, as we show for
the illustrative case of the "core" genome in bacteria.Comment: 18 pages, 7 main figures, 7 supplementary figure
In ascolto dell’America. Popoli, culture, religioni, strade per il futuro. Atti del Convegno Internazionale (Pontificia Università Urbaniana, 7-9 aprile 2014), a cura di A. Trevisiol, Urbaniana University Press, Città del Vaticano 2014, pp. 477.
The use of NEG pumps and coatings in large vacuum systems: experience and limitations
Today Non Evaporable Getter (NEG) materials are commonly used for vacuum production in large vacuum systems, in particular in particle accelerators. Recently, a new technology based on NEG sputtering techniques was successfully developed by CERN and utilized at various synchrotron light sources and ion collider facilities. The aim was to improve the vacuum performance in some conductance limited vacuum systems in order to minimize the gas bremsstrahlung emission and to reduce the impact of the electron-cloud instability discovered in some machines. The most recent results obtained are presented
Reversal of gastrointestinal carcinoma-induced immunosuppression and induction of antitumoural immunity by a combination of cyclophosphamide and gene transfer of IL-12
Immunotherapy-based strategies for gastrointestinal carcinomas (GIC) have been exploited so far, but these approaches have to face strong mechanisms of immune escape induced by tumours. We previously demonstrated that sub-therapeutic doses of an adenovirus expressing IL-12 genes (AdIL-12) mediated a potent antitumour effect against subcutaneous (s.c.) colorectal carcinomas (CRC) in mice pre-treated with low doses of cyclophosphamide (Cy). In our study we used this combination to assess its impact on the immunosuppressive microenvironment. In s.c. CRC model we demonstrated that non-responder mice failed to decrease Tregs in tumour, spleen and peripheral blood. Reconstitution of Tregs into tumour-bearing mice treated with combined therapy abolished the antitumoural effect. In addition, Cy + AdIL-12 modified Tregs functionality by inhibiting the in vitro secretion of IL-10 and TGF-β and their ability to inhibit dendritic cells activation. Combined treatment decreased the number of myeloid-derived suppressor cells (MDSCs) in comparison to non-treated mice and, interestingly, administration of Tregs restored splenic MDSCs population. Furthermore, combined therapy potently generated specific cytotoxic IFN-γ-secreting CD4+ T cells able to eradicate established CRC tumours after adoptive transfer. Finally, we evaluated the combination on disseminated CRC and pancreatic carcinoma (PC). Cy + AdIL-12 were able to eradicate liver metastatic CRC (47%) and PC tumour nodules (40%) and to prolong animal survival. The results of this study support the hypothesis that Cy + AdIL-12 might be a valid immunotherapeutic strategy for advanced GIC.Fil: Malvicini, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; ArgentinaFil: Ingolotti, Mariana. Universidad Austral; ArgentinaFil: Piccioni, Flavia Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; ArgentinaFil: García, Mariana Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; ArgentinaFil: Bayo Fina, Juan Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; ArgentinaFil: Atorrasagasti, María Catalina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; ArgentinaFil: Alaniz, Laura Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; ArgentinaFil: Aquino, Jorge Benjamin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; ArgentinaFil: Espinoza, Jaime A.. Universidad Adolfo Ibañez; Chile. Universidad de La Frontera; ChileFil: Gidekel, Manuel. Universidad Adolfo Ibañez; ChileFil: Scharovsky, Olga Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Medicas. Instituto de Genetica Experimental; ArgentinaFil: Matar, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Medicas. Instituto de Genetica Experimental; ArgentinaFil: Mazzolini Rizzo, Guillermo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; Argentin
Zipf and Heaps laws from dependency structures in component systems
Complex natural and technological systems can be considered, on a
coarse-grained level, as assemblies of elementary components: for example,
genomes as sets of genes, or texts as sets of words. On one hand, the joint
occurrence of components emerges from architectural and specific constraints in
such systems. On the other hand, general regularities may unify different
systems, such as the broadly studied Zipf and Heaps laws, respectively
concerning the distribution of component frequencies and their number as a
function of system size. Dependency structures (i.e., directed networks
encoding the dependency relations between the components in a system) were
proposed recently as a possible organizing principles underlying some of the
regularities observed. However, the consequences of this assumption were
explored only in binary component systems, where solely the presence or absence
of components is considered, and multiple copies of the same component are not
allowed. Here, we consider a simple model that generates, from a given ensemble
of dependency structures, a statistical ensemble of sets of components,
allowing for components to appear with any multiplicity. Our model is a minimal
extension that is memoryless, and therefore accessible to analytical
calculations. A mean-field analytical approach (analogous to the "Zipfian
ensemble" in the linguistics literature) captures the relevant laws describing
the component statistics as we show by comparison with numerical computations.
In particular, we recover a power-law Zipf rank plot, with a set of core
components, and a Heaps law displaying three consecutive regimes (linear,
sub-linear and saturating) that we characterize quantitatively
Dendritic cell-based therapeutic cancer vaccines
En los últimos años la inmunoterapia ha revolucionado el tratamiento de pacientes con cáncer avanzado. El mayor conocimiento de la biología tumoral y de la inmunología ha permitido desarrollar tratamientos racionales manipulando el sistema inmunitario con importante impacto clínico. Entre otras estrategias de inmunoterapia contra el cáncer se ha explorado el uso de vacunas terapéuticas basadas en células dendríticas (CD). Las CD son células de origen hematopoyético, que expresan constitutivamente moléculas presentadoras de antígeno, y son funcionalmente las inductoras más potentes de la activación y proliferación de linfocitos T a los que presentan antígenos. Los linfocitos T CD8+ proliferan y adquieren capacidad citotóxica cuando reconocen su antígeno específico presentado en la superficie de CD, aunque solo algunos tipos de CD pueden presentar antígenos internalizados desde el exterior celular a precursores de linfocitos T citotóxicos (a esta función se la llama presentación cruzada). Explotar la inducción de una respuesta inmunitaria adaptativa eficaz se considera una buena opción por su especificidad y prolongada duración de la respuesta. Las CD, gracias a su particular capacidad de presentación antigénica y de estimulación linfocitaria, son capaces de revertir la respuesta inmunitaria antitumoral deficiente que presentan algunos pacientes con cáncer. Las CD se pueden obtener a partir de distintas fuentes, empleando diversos protocolos para generar diferenciación y maduración, y se administran por diversas vías como son subcutánea, intravenosa o intranodal. La gran variedad de protocolos en los que se aplican las CD explica los resultados clínicos tan heterogéneos que se han comunicado hasta la fecha.In recent years immunotherapy has revolutionized the treatment of patients with advanced cancer. The increased knowledge in the tumor immune-biology has allowed developing rational treatments by manipulation of the immune system with significant clinical impact. This rapid development has significantly changed the prognosis of many tumors without treatment options up to date. Other strategies have explored the use of therapeutic vaccines based on dendritic cells (DC) by inducing antitumor immunity. DC are cells of hematopoietic origin, constitutively expressing molecules capable to present antigens, that are functionally the most potent inducers of the activation and proliferation of antigen specific T lymphocytes. The CD8+ T cells proliferate and acquire cytotoxic capacity after recognizing their specific antigen presented on the surface of DC, although only some types of DC can present antigens internalized from outside the cell to precursors of cytotoxic T lymphocytes (this function is called cross-presentation) requiring translocation mechanisms of complex antigens. The induction of an effective adaptive immune response is considered a good option given its specificity, and prolonged duration of response. The DC, thanks to its particular ability of antigen presentation and lymphocyte stimulation, are able to reverse the poor antitumor immune response experienced by patients with cancer. The DC can be obtained from various sources, using different protocols to generate differentiation and maturation, and are administered by various routes such as subcutaneous, intravenous or intranodal. The wide variety of protocols resulted in heterogeneous clinical responses.Fil: Rizzo, Manglio Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto de Investigaciones Médicas Aplicadas. Laboratorio de Terapia Génica y Celular; ArgentinaFil: Alaniz, Laura Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia del Noroeste de la Provincia de Buenos Aires. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Centro de Investigaciones y Transferencia del Noroeste de la Provincia de Buenos Aires; ArgentinaFil: Mazzolini Rizzo, Guillermo Daniel. Instituto de Investigaciones Médicas Aplicadas. Laboratorio de Terapia Génica y Celular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
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