Processing of Presolar Grains around Post-Asymptotic Giant Branch Stars: Silicon Carbide as the Carrier of the 21 Micron Feature

doi: 10.1086/379973Some proto-planetary nebulae (PPNs) exhibit an enigmatic feature in their infrared spectra at ~21 μm. This feature is not seen in the spectra of either the precursors to PPNs, the asymptotic giant branch (AGB) stars, or the successors of PPNs, "normal" planetary nebulae (PNs). However, the 21 μm feature has been seen in the spectra of PNs with Wolf-Rayet central stars. Therefore, the carrier of this feature is unlikely to be a transient species that only exists in the PPN phase. This feature has been attributed to various molecular and solid-state species, none of which satisfy all constraints, although titanium carbide (TiC) and polycyclic aromatic hydrocarbons (PAHs) have seemed the most viable. We present new laboratory data for silicon carbide (SiC) and show that it has a spectral feature that is a good candidate for the carrier of the 21 μm feature. The SiC spectral feature appears at approximately the same wavelength (depending on the polytype/grain size) and has the same asymmetric profile as the observed astronomical feature. We suggest that processing and cooling of the SiC grains known to exist around carbon-rich AGB stars are responsible for the emergence of the enigmatic 21 μm feature. The emergence of this feature in the spectra of post-AGB stars demonstrates the processing of dust due to the changing physical environments around evolving stars.A. M. H. was supported by NSF AST 98-05924

Der Einfluss der Europäischen Union auf städtische Klimapolitik. Eine Analyse der Rolle motivationaler Faktoren

Städte stehen im Zentrum vieler politischer Herausforderungen und bieten ein großes Problemlösungspotential. Dies gilt in besonderem Maße für das Problem des Klimawandels. Die Arbeit untersucht den Einfluss der Europäischen Union auf städtische Klimapolitik und analysiert dabei die Rolle motivationaler Faktoren. Dabei werden Ansätze der Europaforschung und der lokalen Politikforschung verknüpft. Es wird gezeigt, dass die Berücksichtigung der Wahrnehmung der Akteure und ihrer Handlungsorientierungen einen wichtigen Beitrag zur Erfassung der gesamten Bandbreite des möglichen Einflusses von EU-Impulsen leistet

The effect of stellar evolution on SiC dust grain sizes

Stars on the asymptotic giant branch (AGB) produce dust in their circumstellar shells. The nature of the dust-forming environment is influenced by the evolution of the stars, in terms of both chemistry and density, leading to an evolution in the nature of the dust that is produced. Carbon-rich AGB stars are known to produce silicon carbide (SiC). Furthermore, observations of the ~11um SiC feature show that the spectral features change in a sequence that correlates with stellar evolution. We present new infrared spectra of amorphous SiC and show that the ~9um feature seen in both emission and absorption, and correlated with trends in the ~11um feature, may be due to either amorphous SiC or to nano-crystalline diamond with a high proportion of Si substituting for C. Furthermore, we identify SiC absorption in three ISO spectra of extreme carbon stars, in addition to the four presented by Speck et al. (1997). An accurate description of the sequence in the IR spectra of carbon stars requires accounting for both SiC emission and absorption features. This level of detail is needed to infer the role of dust in evolution of carbon stars. Previous attempts to find a sequence in the infrared spectra of carbon stars considered SiC emission features, while neglecting SiC absorption features, leading to an interpretation of the sequence inadequately describes the role of dust. We show that the evolutionary sequence in carbon star spectra is consistent with a grain size evolution, such that dust grains get progressively smaller as the star evolves. The evolution of the grain sizes provides a natural explanation for the shift of the ~11um SiC feature in emission and in absorption. Further evidence for this scenario is seen in both post-AGB star spectra and in meteoritic studies of presolar grains.Comment: accepted by ApJ 8 figure

La comunicación entre el paciente oncológico y los profesionales. El cuestionario de comunicación de la EORTC

The aims of the present work are to introduce to the field of communication between the cancer patient and the professionals, to remark the positive influence communication may have on the patient, and to present the EORTC communication questionnaire. Communication between patient and professional is a key element in the support that is offered to cancer patients. It is important to consider different professionals communicate with cancer patients. There is a need of research in communication between patients and professionals. Two main models of patient care are presented: Paternalistic and Patient-Centered Cancer Care. Patient-Centered Care includes Patient- Centered Communication - PCC. The relation between communication and other PROs - Quality of Life, Information and Satisfaction with Care - is presented. There are cross-cultural differences in communication that could be related to the model of patient care. The European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Group is developing a questionnaire to assess communication between cancer patient and the professionals. This Communication questionnaire mainly assesses professionals’ behaviors. Cultural aspects have a key role in the development of the EORTC questionnaire. This instrument is based on the Patient- Centered Communication – PCC model. The EORTC QLQ-COMU26 is presented. It includes six scales and four individual items. The three phases of the questionnaire development process are described. At the present moment the EORTC QLQ-COMU26 is being field-tested in a larger international study (phase IV), to ensure it is an appropriate and psychometrically valid instrument.Este trabajo pretende introducir el área de la comunicación entre el paciente oncológico y los profesionales, y destacar el impacto que tiene en el paciente. Además, se presenta el cuestionario de comunicación de la EORTC. La comunicación entre el paciente y los profesionales es uno de los elementos claves del soporte que se ofrece a dichos pacientes. En dicha comunicación participan un rango importante de profesionales. Hay una necesidad de realizar más investigación sobre la comunicación. Se presentan dos modelos principales de atención al paciente: el Paternalista y el de Atención Centrada en el Paciente con cáncer. Este último lleva asociada la Comunicación Centrada en el Paciente - CCP. Se revisa la relación entre comunicación y otros PRO: Calidad de Vida, información, y Satisfacción con los Cuidados. Existen diferencias culturales en comunicación que pueden estar relacionadas con el modelo de atención al paciente. El Grupo de Calidad de Vida de la Organización Europea para la Investigación y Tratamiento del Cáncer-EORTC está desarrollando una escala de comunicación entre el paciente oncológico y los profesionales. La mayoría del contenido de dicho cuestionario se centra en las conductas de los profesionales. Los aspectos culturales tienen un papel fundamental en el desarrollo del instrumento. El cuestionario se basa en el modelo de Comunicación Centrada en el Paciente – CCP. Se presenta el cuestionario EORTC QLQ-COMU26, que consta de seis escalas y cuatro ítems individuales. Se describen las tres primeras fases que se han dado en su creación. En la actualidad su funcionamiento psicométrico se está valorando en un estudio internacional

Intratumoral macrophages contribute to epithelial-mesenchymal transition in solid tumors

<p>Abstract</p> <p>Background</p> <p>Several stromal cell subtypes including macrophages contribute to tumor progression by inducing epithelial-mesenchymal transition (EMT) at the invasive front, a mechanism also linked to metastasis. Tumor associated macrophages (TAM) reside mainly at the invasive front but they also infiltrate tumors and in this process they mainly assume a tumor promoting phenotype. In this study, we asked if TAMs also regulate EMT intratumorally. We found that TAMs through TGF-β signaling and activation of the β-catenin pathway can induce EMT in intratumoral cancer cells.</p> <p>Methods</p> <p>We depleted macrophages in F9-teratocarcinoma bearing mice using clodronate-liposomes and analyzed the tumors for correlations between gene and protein expression of EMT-associated and macrophage markers. The functional relationship between TAMs and EMT was characterized <it>in vitro </it>in the murine F9 and mammary gland NMuMG cells, using a conditioned medium culture approach. The clinical relevance of our findings was evaluated on a tissue microarray cohort representing 491 patients with non-small cell lung cancer (NSCLC).</p> <p>Results</p> <p>Gene expression analysis of F9-teratocarcinomas revealed a positive correlation between TAM-densities and mesenchymal marker expression. Moreover, immunohistochemistry showed that TAMs cluster with EMT phenotype cells in the tumors. <it>In vitro</it>, long term exposure of F9-and NMuMG-cells to macrophage-conditioned medium led to decreased expression of the epithelial adhesion protein E-cadherin, activation of the EMT-mediating β-catenin pathway, increased expression of mesenchymal markers and an invasive phenotype. In a candidate based screen, macrophage-derived TGF-β was identified as the main inducer of this EMT-associated phenotype. Lastly, immunohistochemical analysis of NSCLC patient samples identified a positive correlation between intratumoral macrophage densities, EMT markers, intraepithelial TGF-β levels and tumor grade.</p> <p>Conclusions</p> <p>Data presented here identify a novel role for macrophages in EMT-promoted tumor progression. The observation that TAMs cluster with intra-epithelial fibroblastoid cells suggests that the role of macrophages in tumor-EMT extends beyond the invasive front. As macrophage infiltration and pronounced EMT tumor phenotype correlate with increased grade in NSCLC patients, we propose that TAMs also promote tumor progression by inducing EMT locally in tumors.</p

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

A Spectroscopic and Chemical Study of the Coloration of Feldspars by Irradiation and Impurities, Including Water

Natural smoky color or smoky color induced by ionizing radiation develops only in potassium feldspars (KAlSi3O8) free of water bound in the feldspar structure. Neither fluid inclusion water nor ≡SiOH have an effect. The optical absorption spectra of the smoky color consist of polarized bands at 11600, 16200, 19100, and 27200 cm-1, whose integrated intensities are linearly correlated with the integrated intensity of a broad, asymmetric first derivative at geff = 2.027 in electron paramagnetic resonance (EPR) spectra. This hole center forms only in KAlSi3O8 without structurally bound H2O, and in microcline is resolved into an asymmetric six-line pattern at geff = 2.024 and a single derivative at geff = 2.009 which are Si-O- -K and a hole shared between two nonbonding oxygens (NBO) on Si. In analogy to coloring in quartz and glass, the 11600 cm-1 band is caused by a hole trapped between two NBO's on silicon, the 16200 and 27200 cm-1 bands are due to the Si-O- -K center, and the 19100 cm-1 band results from a hole trapped on an oxygen attached to two aluminums. Smoky centers do not develop in feldspars with structural water because irradiation mobilizes protons which, while diffusing, destroy centers in their path, and finally then settle in sites similar to their original site. Smoky color also develops in sodic plagioclases, but high Al content inhibits its formation in labradorite. Amazonite color is intrinsic and controlled by an absorption minimum between three overlapping bands in the ultraviolet and a broad band in β at 630, or one UV band and a broad band in β at 720 nm, or both superimposed. Comparison of EPR to optical integrated intensities shows that all three colors are connected with a first derivative at geff = 1.56 and two satellites of about 1/7 intensity at geff of 1.83 and 1.39. Analysis of the EPR pattern shows that this center is Pb3+ 31% of the time, with the hole located on coordinating oxygens for the remaining 69%. This center is only produced in samples which have in addition to Pb, H2O structurally bound in the lattice. The dependence of color intensity on the smaller molar concentration of structural water or lead implies that lead and structural water in a 1:1 ratio produce color centers in amazonite. The first order reaction kinetics of amazonite color formation by irradiation and the observation that water is not consumed in the process suggests that Pb2+ is oxidized to Pb3+ by the product OH of the irradiation-induced dissociation of water while H concurrently destroys a hole center on an oxygen, and is followed by the regeneration of the water molecule. The kinetics also show that the radiation necessary for the coloration is provided by internal decay of 40K. The two end-member color types (630 or 720 nm) occur for microcline or orthoclase local structure, respectively. Al/Si disorder increases first locally, and then overall as larger amounts Pb or H2O are incorporated, so that crystals with intermediate Pb contents have both color types. A spectrally similar blue radiation color also occurs for Pb-bearing sodic plagioclases. Gemmy labradorite phenocrysts from one Steens Mountain basalt flow in Rabbit Basin, Oregon, sometimes possess a pink schiller, or more rarely a transparent red or green coloration. Direct microprobe analysis of the schiller flakes show that these are metallic copper. XRF analysis of the different colored zones revealed that only the copper content varies with color: colorless samples, or sections of crystals, have 0-35 ppm Cu; greens average 80 ppm Cu; reds average 135 ppm Cu; while schiller bearing labradorites have 50 to 240 ppm Cu. Spectral similarity of the red color to copper-ruby color of glass shows that the red arises from the intrinsic absorption of colloidal Cuo particles that are too small to scatter light (ca. 4 to 22 nm). Spectra from the green regions strongly resemble that of amazonite. Because the temperature of exsolution is subsolidus and proportional to Cu content, diffusion proceeds more rapidly for crystals with higher Cu content and results in formation of larger particles. The Cuo reduction at low temperature (800°C) involves formation of hole center (O-) that is captured by Pb2+ to form the green amazonite color (Pb3+). At high temperatures (~ 900 to 1100°C) the reduction of Cu is controlled by whatever reactions occur in the basalt to keep fO2 along the QFM buffer. Migration of Cuo may cause the variation of Cu concentrations in a single sample; but the variation of Cu content among different crystals suggests that the composition of the megacrysts was not constant and changed in response to an increasing copper content in the melt as crystallization of the labradorite proceeded. The coloration process in feldspar strongly resembles that in glasses for both radiation colors (smoky) and exsolution phenomena (Cuo colloids, Cuo schiller) and also that of radiation colors in other crystalline solids (smoky quartz, Pb3+ or Tl2+ in KCl). Although quartz and glass are structurally and chemically similar to feldspar, KCl is not, suggesting that for the most part it is the behavior of the chemical impurity on an atomic level which controls the coloring mechanism.</p

Theoretical and Observational Constraints on Lunar Orbital Evolution in the Three-Body Earth-Moon-Sun System

Extremely slow recession of the Moon from the Earth has been recently proposed and attributed to conversion of Earth&rsquo;s axial spin to lunar orbital momentum. This hypothesis is inconsistent with long-standing recognition that the Moon&rsquo;s orbit involves three-body interactions. This and other short-comings, such as Earth&rsquo;s spin loss being internal, are summarized here. Considering point-masses is justified by theory and observational data on other moons. We deduce that torque in the Earth-Moon-Sun system increases eccentricity of the lunar orbit but decreases its inclination over time. Consequently, the average lunar orbital radius is decreasing. We also show that lunar drift is too small to be constrained through lunar laser ranging measurements, mainly because atmospheric refraction corrections are comparatively large and variations in lunar cycles are under-sampled. Our findings support co-accretion and explain how orbits evolve in many-body point-mass systems