SWCam: the short wavelength camera for the CCAT Observatory

We describe the Short Wavelength Camera (SWCam) for the CCAT observatory including the primary science drivers, the coupling of the science drivers to the instrument requirements, the resulting implementation of the design, and its performance expectations at first light. CCAT is a 25 m submillimeter telescope planned to operate at 5600 meters, near the summit of Cerro Chajnantor in the Atacama Desert in northern Chile. CCAT is designed to give a total wave front error of 12.5 μm rms, so that combined with its high and exceptionally dry site, the facility will provide unsurpassed point source sensitivity deep into the short submillimeter bands to wavelengths as short as the 200 μm telluric window. The SWCam system consists of 7 sub-cameras that address 4 different telluric windows: 4 subcameras at 350 μm, 1 at 450 μm, 1 at 850 μm, and 1 at 2 mm wavelength. Each sub-camera has a 6’ diameter field of view, so that the total instantaneous field of view for SWCam is equivalent to a 16’ diameter circle. Each focal plane is populated with near unit filling factor arrays of Lumped Element Kinetic Inductance Detectors (LEKIDs) with pixels scaled to subtend an solid angle of (λ/D)2 on the sky. The total pixel count is 57,160. We expect background limited performance at each wavelength, and to be able to map < 35(°)2 of sky to 5 σ on the confusion noise at each wavelength per year with this first light instrument. Our primary science goal is to resolve the Cosmic Far-IR Background (CIRB) in our four colors so that we may explore the star and galaxy formation history of the Universe extending to within 500 million years of the Big Bang. CCAT's large and high-accuracy aperture, its fast slewing speed, use of instruments with large format arrays, and being located at a superb site enables mapping speeds of up to three orders of magnitude larger than contemporary or near future facilities and makes it uniquely sensitive, especially in the short submm bands

MAKO: a pathfinder instrument for on-sky demonstration of low-cost 350 micron imaging arrays

Submillimeter cameras now have up to 10^4 pixels (SCUBA 2). The proposed CCAT 25-meter submillimeter telescope will feature a 1 degree field-of-view. Populating the focal plane at 350 microns would require more than 10^6 photon-noise limited pixels. To ultimately achieve this scaling, simple detectors and high-density multiplexing are essential. We are addressing this long-term challenge through the development of frequency-multiplexed superconducting microresonator detector arrays. These arrays use lumped-element, direct-absorption resonators patterned from titanium nitride films. We will discuss our progress toward constructing a scalable 350 micron pathfinder instrument focusing on fabrication simplicity, multiplexing density, and ultimately a low per-pixel cost

The magnetic field in the Flame nebula

Star formation is essential in galaxy evolution and the cycling of matter. The support of interstellar clouds against gravitational collapse by magnetic (B-) fields has been proposed to explain the low observed star formation efficiency in galaxies and the Milky Way. Despite the Planck satellite providing a 5-15' all-sky map of the B-field geometry in the diffuse interstellar medium, higher spatial resolution observations are required to understand the transition from diffuse gas to gravitationally unstable filaments. NGC 2024, the Flame Nebula, in the nearby Orion B molecular cloud, contains a young, expanding HII region and a dense filament that harbors embedded protostellar objects. Therefore, NGC 2024 is an excellent opportunity to study the role of B-fields in the formation, evolution, and collapse of filaments, as well as the dynamics and effects of young HII regions on the surrounding molecular gas. We combine new 154 and 216 micron dust polarization measurements carried out using the HAWC+ instrument aboard SOFIA with molecular line observations of 12CN(1-0) and HCO+(1-0) from the IRAM 30-meter telescope to determine the B-field geometry and to estimate the plane of the sky magnetic field strength across the NGC 2024. The HAWC+ observations show an ordered B-field geometry in NGC 2024 that follows the morphology of the expanding HII region and the direction of the main filament. The derived plane of the sky B-field strength is moderate, ranging from 30 to 80 micro G. The strongest B-field is found at the northern-west edge of the HII region, characterized by the highest gas densities and molecular line widths. In contrast, the weakest field is found toward the filament in NGC 2024. The B-field has a non-negligible influence on the gas stability at the edges of the expanding HII shell (gas impacted by the stellar feedback) and the filament (site of the current star formation).Comment: 36 pages, 26 figures Accepted for publication in Astronomy & Astrophysic

SWCam: the short wavelength camera for the CCAT Observatory

We describe the Short Wavelength Camera (SWCam) for the CCAT observatory including the primary science drivers, the coupling of the science drivers to the instrument requirements, the resulting implementation of the design, and its performance expectations at first light. CCAT is a 25 m submillimeter telescope planned to operate at 5600 meters, near the summit of Cerro Chajnantor in the Atacama Desert in northern Chile. CCAT is designed to give a total wave front error of 12.5 μm rms, so that combined with its high and exceptionally dry site, the facility will provide unsurpassed point source sensitivity deep into the short submillimeter bands to wavelengths as short as the 200 μm telluric window. The SWCam system consists of 7 sub-cameras that address 4 different telluric windows: 4 subcameras at 350 μm, 1 at 450 μm, 1 at 850 μm, and 1 at 2 mm wavelength. Each sub-camera has a 6’ diameter field of view, so that the total instantaneous field of view for SWCam is equivalent to a 16’ diameter circle. Each focal plane is populated with near unit filling factor arrays of Lumped Element Kinetic Inductance Detectors (LEKIDs) with pixels scaled to subtend an solid angle of (λ/D)2 on the sky. The total pixel count is 57,160. We expect background limited performance at each wavelength, and to be able to map < 35(°)2 of sky to 5 σ on the confusion noise at each wavelength per year with this first light instrument. Our primary science goal is to resolve the Cosmic Far-IR Background (CIRB) in our four colors so that we may explore the star and galaxy formation history of the Universe extending to within 500 million years of the Big Bang. CCAT's large and high-accuracy aperture, its fast slewing speed, use of instruments with large format arrays, and being located at a superb site enables mapping speeds of up to three orders of magnitude larger than contemporary or near future facilities and makes it uniquely sensitive, especially in the short submm bands

Energy Flow in the Hadronic Final State of Diffractive and Non-Diffractive Deep-Inelastic Scattering at HERA

An investigation of the hadronic final state in diffractive and non--diffractive deep--inelastic electron--proton scattering at HERA is presented, where diffractive data are selected experimentally by demanding a large gap in pseudo --rapidity around the proton remnant direction. The transverse energy flow in the hadronic final state is evaluated using a set of estimators which quantify topological properties. Using available Monte Carlo QCD calculations, it is demonstrated that the final state in diffractive DIS exhibits the features expected if the interaction is interpreted as the scattering of an electron off a current quark with associated effects of perturbative QCD. A model in which deep--inelastic diffraction is taken to be the exchange of a pomeron with partonic structure is found to reproduce the measurements well. Models for deep--inelastic $ep$ scattering, in which a sizeable diffractive contribution is present because of non--perturbative effects in the production of the hadronic final state, reproduce the general tendencies of the data but in all give a worse description.Comment: 22 pages, latex, 6 Figures appended as uuencoded fil

Crosstalk between glial and glioblastoma cells triggers the "go-or-grow" phenotype of tumor cells

Background: Glioblastoma (GBM), the most malignant primary brain tumor, leads to poor and unpredictable clinical outcomes. Recent studies showed the tumor microenvironment has a critical role in regulating tumor growth by establishing a complex network of interactions with tumor cells. In this context, we investigated how GBM cells modulate resident glial cells, particularly their paracrine activity, and how this modulation can influence back on the malignant phenotype of GBM cells. Methods: Conditioned media (CM) of primary mouse glial cultures unexposed (unprimed) or exposed (primed) to the secretome of GL261 GBM cells were analyzed by proteomic analysis. Additionally, these CM were used in GBM cells to evaluate their impact in glioma cell viability, migration capacity and activation of tumor-related intracellular pathways. Results: The proteomic analysis revealed that the pre-exposure of glial cells to CM from GBM cells led to the upregulation of several proteins related to inflammatory response, cell adhesion and extracellular structure organization within the secretome of primed glial cells. At the functional levels, CM derived from unprimed glial cells favored an increase in GBM cell migration capacity, while CM from primed glial cells promoted cells viability. These effects on GBM cells were accompanied by activation of particular intracellular cancer-related pathways, mainly the MAPK/ERK pathway, which is a known regulator of cell proliferation. Conclusions: Together, our results suggest that glial cells can impact on the pathophysiology of GBM tumors, and that the secretome of GBM cells is able to modulate the secretome of neighboring glial cells, in a way that regulates the "go-or-grow" phenotypic switch of GBM cells.Fundação para a Ciência e Tecnologia (IF/00601/2012 to B.M.C.; IF/00111 to A.J.S; SFRH/BD/52287/2013 to A.I.O.; SFRH/BD/81495/2011 to S.I.A.; SFRH/BD/88121/2012 to J.V.C.; projects PTDC/SAU-GMG/113795/2009 to B.M.C.; PTDC/NEU-NMC/0205/2012, PTDC/NEU-SCC/7051/2014, PEst-C/SAU/LA0001/2013–2014 and UID/NEU/04539/2013 to B.M.), Liga Portuguesa Contra o Cancro (B.M.C.), Fundação Calouste Gulbenkian (B.M.C.) and Inter-University Doctoral Programme in Ageing and Chronic Disease (PhDOC; to A.I.O.). Project co-financed by Programa Operacional Regional do Norte (ON.2—O Novo Norte), Quadro de Referência Estratégico Nacional (QREN), Fundo Europeu de Desenvolvimento Regional (FEDER), Programa Operacional Factores de Competitividade (COMPETE), and by The National Mass Spectrometry Network (RNEM) under the contract REDE/1506/REM/2005info:eu-repo/semantics/publishedVersio

The Protein-Protein Interaction tasks of BioCreative III: classification/ranking of articles and linking bio-ontology concepts to full text

BACKGROUND: Determining usefulness of biomedical text mining systems requires realistic task definition and data selection criteria without artificial constraints, measuring performance aspects that go beyond traditional metrics. The BioCreative III Protein-Protein Interaction (PPI) tasks were motivated by such considerations, trying to address aspects including how the end user would oversee the generated output, for instance by providing ranked results, textual evidence for human interpretation or measuring time savings by using automated systems. Detecting articles describing complex biological events like PPIs was addressed in the Article Classification Task (ACT), where participants were asked to implement tools for detecting PPI-describing abstracts. Therefore the BCIII-ACT corpus was provided, which includes a training, development and test set of over 12,000 PPI relevant and non-relevant PubMed abstracts labeled manually by domain experts and recording also the human classification times. The Interaction Method Task (IMT) went beyond abstracts and required mining for associations between more than 3,500 full text articles and interaction detection method ontology concepts that had been applied to detect the PPIs reported in them.RESULTS:A total of 11 teams participated in at least one of the two PPI tasks (10 in ACT and 8 in the IMT) and a total of 62 persons were involved either as participants or in preparing data sets/evaluating these tasks. Per task, each team was allowed to submit five runs offline and another five online via the BioCreative Meta-Server. From the 52 runs submitted for the ACT, the highest Matthew's Correlation Coefficient (MCC) score measured was 0.55 at an accuracy of 89 and the best AUC iP/R was 68. Most ACT teams explored machine learning methods, some of them also used lexical resources like MeSH terms, PSI-MI concepts or particular lists of verbs and nouns, some integrated NER approaches. For the IMT, a total of 42 runs were evaluated by comparing systems against manually generated annotations done by curators from the BioGRID and MINT databases. The highest AUC iP/R achieved by any run was 53, the best MCC score 0.55. In case of competitive systems with an acceptable recall (above 35) the macro-averaged precision ranged between 50 and 80, with a maximum F-Score of 55. CONCLUSIONS: The results of the ACT task of BioCreative III indicate that classification of large unbalanced article collections reflecting the real class imbalance is still challenging. Nevertheless, text-mining tools that report ranked lists of relevant articles for manual selection can potentially reduce the time needed to identify half of the relevant articles to less than 1/4 of the time when compared to unranked results. Detecting associations between full text articles and interaction detection method PSI-MI terms (IMT) is more difficult than might be anticipated. This is due to the variability of method term mentions, errors resulting from pre-processing of articles provided as PDF files, and the heterogeneity and different granularity of method term concepts encountered in the ontology. However, combining the sophisticated techniques developed by the participants with supporting evidence strings derived from the articles for human interpretation could result in practical modules for biological annotation workflows

Jets and energy flow in photon-proton collisions at HERA

Properties of the hadronic final state in photoproduction events with large transverse energy are studied at the electron-proton collider HERA. Distributions of the transverse energy, jets and underlying event energy are compared to \overline{p}p data and QCD calculations. The comparisons show that the \gamma p events can be consistently described by QCD models including -- in addition to the primary hard scattering process -- interactions between the two beam remnants. The differential jet cross sections d\sigma/dE_T^{jet} and d\sigma/d\eta^{jet} are measured