Rebirth of X-ray Emission from the Born-Again Planetary Nebula A 30

The planetary nebula (PN) A30 is believed to have undergone a very late thermal pulse resulting in the ejection of knots of hydrogen-poor material. Using HST images we have detected the angular expansion of these knots and derived an age of 850+280-150 yr. To investigate the spectral and spatial properties of the soft X-ray emission detected by ROSAT, we have obtained Chandra and XMM-Newton observations of A30. The X-ray emission from A30 can be separated into two components: a point-source at the central star and diffuse emission associated with the hydrogen-poor knots and the cloverleaf structure inside the nebular shell. To help us assess the role of the current stellar wind in powering this X-ray emission, we have determined the stellar parameters of the central star of A 30 using a non-LTE model fit to its optical and UV spectrum. The spatial distribution and spectral properties of the diffuse X-ray emission is suggestive that it is generated by the post-born-again and present fast stellar winds interacting with the hydrogen-poor ejecta of the born-again event. This emission can be attributed to shock-heated plasma, as the hydrogen-poor knots are ablated by the stellar winds, under which circumstances the efficient mass-loading of the present fast stellar wind raises its density and damps its velocity to produce the observed diffuse soft X-rays. Charge transfer reactions between the ions of the stellar winds and material of the born-again ejecta has also been considered as a possible mechanism for the production of diffuse X-ray emission, and upper limits on the expected X-ray production by this mechanism have been derived. The origin of the X-ray emission from the central star of A 30 is puzzling: shocks in the present fast stellar wind and photospheric emission can be ruled out, while the development of a new, compact hot bubble confining the fast stellar wind seems implausible.Comment: 29 pages, 11 figures, 4 tables; accepted for publication by Ap

Chandra's Close Encounter with the Disintegrating Comets 73P/2006 (Schwassmann--Wachmann--3) Fragment B and C/1999 S4 (LINEAR)

On May 23, 2006 we used the ACIS-S instrument on the Chandra X-ray Observatory (CXO) to study the X-ray emission from the B fragment of comet 73P/2006 (Schwassmann-Wachmann 3) (73P/B). We obtained a total of 20 ks of CXO observation time of Fragment B, and also investigated contemporaneous ACE and SOHO solar wind physical data. The CXO data allow us to spatially resolve the detailed structure of the interaction zone between the solar wind and the fragment's coma at a resolution of ~ 1,000 km, and to observe the X-ray emission due to multiple comet--like bodies. We detect a change in the spectral signature with the ratio of the CV/OVII line increasing with increasing collisional opacity as predicted by Bodewits \e (2007). The line fluxes arise from a combination of solar wind speed, the species that populate the wind and the gas density of the comet. We are able to understand some of the observed X-ray morphology in terms of non-gravitational forces that act upon an actively outgassing comet's debris field. We have used the results of the Chandra observations on the highly fragmented 73P/B debris field to re-analyze and interpret the mysterious emission seen from comet C/1999 S4 (LINEAR) on August 1st, 2000, after the comet had completely disrupted. We find the physical situations to be similar in both cases, with extended X-ray emission due to multiple, small outgassing bodies in the field of view. Nevertheless, the two comets interacted with completely different solar winds, resulting in distinctly different spectra.Comment: accepted by ApJ, 44 Pages, including 4 tables and 14 figure

Nous – infinis entre deux fins

Dans cet article, je tente d’étudier l’oscillation entre les concepts de fini et d’infini dans divers textes de Jacques Derrida et son incidence sur les problématiques de la promesse et de la mort. Cette étude me conduit à considérer une proposition de Jacques Derrida sur un « nous infini » face au « soleil fini » comme une réécriture du Soleil placé en abîme de Francis Ponge.In this paper, I set out to study the oscillation between the concepts of « the finite » and « the infinite » in a series of texts by Jacques Derrida as well as its effect on the issues of promise and death. This study leads me to consider the idea of a « nous infini », in relationship to the « soleil fini » that was put forth by Jacques Derrida in his rewriting of Francis Ponge’s Soleil placé en abîme

Simultaneous Swift X-ray and UV views of comet C/2007 N3 (Lulin)

We present an analysis of simultaneous X-Ray and UV observations ofcomet C/2007 N3 (Lulin) taken on three days between January 2009 and March 2009 using the Swift observatory. For our X-ray observations, we used basic transforms to account for the movement of the comet to allow the combination of all available data to produce an exposure-corrected image. We fit a simple model to the extracted spectrum and measured an X-ray flux of 4.3+/-1.3 * 10^-13 ergs cm-2 s-1 in the 0.3 to 1.0 keV band. In the UV, we acquired large-aperture photometry and used a coma model to derive water production rates given assumptions regarding the distribution of water and its dissociation into OH molecules about the comet's nucleus. We compare and discuss the X-ray and UV morphology of the comet. We show that the peak of the cometary X-ray emission is offset sunward of the UV peak emission, assumed to be the nucleus, by approximately 35,000 km. The offset observed, the shape of X-ray emission and the decrease of the X-ray emission comet-side of the peak, suggested that the comet was indeed collisionally thick to charge exchange, as expected from our measurements of the comet's water production rate (6--8 10^28 mol. s-1). The X-ray spectrum is consistent with solar wind charge exchange emission, and the comet most likely interacted with a solar wind depleted of very highly ionised oxygen. We show that the measured X-ray lightcurve can be very well explained by variations in the comet's gas production rates, the observing geometry and variations in the solar wind flux.Comment: Paper accepted for publication in Astronomy and Astrophysics, 6 March 2012, 12 pages, 8 colour figures, one tabl

Ventilation inhomogeneity in patients with cystic fibrosis measured by electrical impedance tomography

Objective: The distribution of ventilation within the lung is inhomogeneous. We hypothesized that the degree of inhomogeneity in patients with cystic fibrosis (CF) differs from that in healthy subjects. Method: Three adult patients with cystic fibrosis (CF) and two healthy subjects were recruited for this preliminary study. Subjects were asked to breathe in as deep and exhale as hard as possible three times. Electrical impedance tomography (EIT) measurements were performed during spirometry tests. The global inhomogeneity index(GI) was applied to assess the degree of ventilation homogeneity at 25%, 50%, 75% and 100% of maximum inspiratory volume. Results: Airway obstruction was detected in CF patients but not in healthy volunteers during spirometry tests. GI decreased as inspiratory volume increased in CF patients (0.59+/-0.20 at 25% and 0.39+/-0.09 at 100%, p<0.01, mean+/-SD) while GI remained unchanged in healthy subjects (0.40+/-0.05 at 25% and 0.37+/-0.03 at 100%, p=0.31). Conclusion: Degree of ventilation homogeneity appears to vary during forced respiration in CF patients, but not in healthy volunteers. EIT is a practical method to measure the inhomogeneity of ventilation distribution

Synthesis and Applications of Fluorinated Multi-Carbonyl Systems via Batch and Flow Processes

Organofluorine chemistry has played a significant role in the majority of the spectacular scientific and technological developments of the past century. Two key challenges in organofluorine chemistry remain selective methods for the formation of carbon-fluorine bonds and the synthesis of complex fluorinated molecules under mild conditions. The incorporation of fluorine atoms into a pharmaceutical candidate is a well established approach to, for example, affect lipophilicity, pKa and metabolic stability of new chemical entities as part of drug discovery programs. Consequently, effective and inexpensive methodologies for the synthesis of selectively fluorinated multifunctional building blocks for incorporation into drug synthesis campaigns are very desirable. In the context of developing the use of 2-fluoro-1,3-dicarbonyl substrates for the synthesis of more structurally complex fluorinated intermediates, we investigated routes to various fluorinated systems. As part of a general strategy aimed at assessing the effect of the carbon-fluorine bond attached to the reactive enolic site of the 2-fluoro-1,3-dicarbonyl system, we used this reactivity profile for the synthesis of pharmaceutically relevant fluorinated intermediates. Several APIs present a fluoro-pyrimidinone structure, therefore a synthetic pathway giving access to functionalized fluorinated pyrimidinones has been established. Secondly, after testing various radical initiators, we applied a free radical chemistry strategy to reactions of 2-fluoro-1,3-dicarbonyl systems using Ceric Ammonium Nitrate (CAN) and various olefins, affording fluorinated nitro-oxy products by a catalytic oxidative addition. Finally, as the value of multicomponent reactions (MCRs) in drug development gives rapid access to large libraries of molecules possessing a high degree of functionality and structural diversity, we developed a synthetic strategy using β-fluoroketoesters and β-fluoromalonate substrates as MCR components in Mannich reactions involving various aldehydes and amines, using both batch and flow processes. Additionally, we investigated the potential use of fluorinated 1,3-dicarbonyl systems to act as nucleophiles in nucleophilic substitutions involving poly-fluorinated aromatic systems and also studied the direct fluorination of functionalized tri-carbonyl systems

REFLEKSI MORALITAS MASYARAKAT MALUKU DALAM NASKAH TEATER BAMETI KARYA CHALVIN PAPILAYA (KAJIAN SOSIOLOGI SASTRA)

Tujuan penelitian ini adalah mendeskripsikan moralitas masyarakat Maluku dalam naskah teater Bameti Karya Chalvin Papilaya dengan menggunakan pendekatan sosiologi sastra. Tipe penelitian yang digunakan dalam penelitian ini adalah kualitatif. Data dalam penelitian ini berupa dialog yang menunjukkan refleksi moralitas masyarakat Maluku dalam naskah teater Bameti, Karya Chalvin Papilaya. Sumber data dalam penelitian ini adalah naskah teater Bameti karya Chalvin Papilaya. Teknik pengumpulan data dalam penelitian ini adalah teknik baca catat dan teknik kepustakaan. Teknik baca catat dengan menggunakan cara membaca seluruh naskah Bameti secara berulang-ulang dan teliti, kemudian dicatat bagian-bagian peting berupa kata, frasa, ataupun kalimat yang menunjukan moralitas masyarakat. Teknik kepustakaan, digunakan untuk mencari referensi yang sesuai dengan bahan kajian berupa penjelasan pendekatan sosiologi sastra dan data berupa naskah teater Bameti. Teknik analisis yang digunakan yaitu analisis deskriptif kualitatif. Teknik mengecekan keabsahan data dengan menggunakan triangulasi teori karena data penelitian ini akan diuji kebenarannya menggunakan teori yang dipakai yaitu teori sosiologi sastra. Cara kerja dengan teori sastra mendeskripsikan kata-kata, frasa, atau kalimat yang mencerminkan moralitas masyarakat dengan menggunakan sosiologi sastra. Hal ini dimaksudkan untuk mendapat kebenaran data atau kesesuaian dengan teori yang dipakai

Applying system dynamics for outsourcing services in design-build projects

This study analysed a system dynamics model for outsourcing engineering services in a large and complex project organisational structure that is typically associated with design-build (DB) project delivery. A literature review indicated that most of the reviewed papers implied the project engineering resources were totally insourced or the authors were silent regarding any resources that were outsourced. Comprehensive sensitivity analysis of various model variables was performed, which indicates that the quality and productivity of the outsourced resources as well as the initial number of assigned experienced engineers significantly impacted the amount and timing of engineering work completion. Project outcomes were also impacted by varying the number of initial and changed engineering tasks. The decision to insource/outsource engineering work on DB projects may have significant cost and time impacts, which should be considered by decision makers