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The PPE Domain of PPE17 Is Responsible for Its Surface Localization and Can Be Used to Express Heterologous Proteins on the Mycobacterial Surface  [PDF]
Valentina Donà, Marcello Ventura, Michela Sali, Alessandro Cascioferro, Roberta Provvedi, Giorgio Palù, Giovanni Delogu, Riccardo Manganelli
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0057517
Abstract: PPE represent a peculiar family of mycobacterial proteins characterized by a 180 aminoacids conserved N-terminal domain. Several PPE genes are co-transcribed with a gene encoding for a protein belonging to another family of mycobacterial specific proteins named PE. Only one PE-PPE couple has been extensively characterized so far (PE25-PPE41) and it was shown that these two proteins form a heterodimer and that this interaction is essential for PPE41 stability and translocation through the mycobacterial cell wall. In this study we characterize the PE11-PPE17 couple. In contrast with what was found for PE25-PPE41, we show that PPE17 is not secreted but surface exposed. Moreover, we demonstrate that the presence of PE11 is not necessary for PPE17 stability or for its localization on the mycobacterial surface. Finally, we show that the PPE domain of PPE17 targets the mycobacterial cell wall and that this domain can be used as a fusion partner to expose heterologous proteins on the mycobacterial surface.
Prospects for Asymmetric PNe with ALMA  [PDF]
P. J. Huggins
Physics , 2010,
Abstract: Millimeter and sub-millimeter observations have made fundamental contributions to our current understanding of the transition from AGB stars to white dwarfs. The approaching era of ALMA brings significantly enhanced observing capabilities at these wavelengths and promises to push back the frontiers in a number of ways. We examine the scientific prospects of this new era for PNe, with an emphasis on how developments may contribute to the goals of the asymmetric PNe community.
DENIS Survey Data Probing Different Types of PNe  [PDF]
S. Schmeja,S. Kimeswenger
Physics , 2002,
Abstract: We present near-infrared photometry of a large sample of planetary nebulae (PNe) and show that the IJK colours are a good tool to distinguish different classes of PNe, like nebulae around symbiotic Miras or IR-[WC] PNe from genuine PNe.
Additivity of the dp-rank  [PDF]
Itay Kaplan,Alf Onshuus,Alexander Usvyatsov
Mathematics , 2011,
Abstract: The main result of this article is sub-additivity of the dp-rank. We also show that the study of theories of finite dp-rank can not be reduced to the study of its dp-minimal types, and discuss the possible relations between dp-rank and VC-density.
Effects of CSPN Models on PNe Shell Modeling  [PDF]
B. Armsdorfer,S. Kimeswenger,T. Rauch
Physics , 2001,
Abstract: Modeling planetary nebulae (PNe) shells using different ionizing spectra for a hot central star (CSPN) of evolved PNe, we found that especially a blackbody model leads to wrong nebular diagnostics and abundances.
Magnetic Collimation in PNe  [PDF]
T. A. Gardiner,A. Frank
Physics , 2001, DOI: 10.1086/321494
Abstract: Recent studies have focused on the the role of initially weak toroidal magnetic fields embedded in a stellar wind as the agent for collimation in planetary nebulae. In these models the wind is assumed to be permeated by a helical magnetic field in which the poloidal component falls off faster than the toroidal component. The collimation only occurs after the wind is shocked at large distances from the stellar source. In this paper we re-examine assumptions built into this ``Magnetized Wind Blown Bubble'' (MWBB) model. We show that a self-consistent study of the model leads to a large parameter regime where the wind is self-collimated before the shock wave is encountered. We also explore the relation between winds in the MWBB model and those which are produced via magneto-centrifugal processes. We conclude that a more detailed examination of the role of self-collimation is needed in the context of PNe studies.
Witnessing dp-rank  [PDF]
Itay Kaplan,Pierre Simon
Mathematics , 2012,
Abstract: We prove that in NTP_2 theories if p is a dependent type with dp-rank >= \kappa, then this can be witnessed by indiscernible sequences of tuples satisfying p. If p has dp-rank infinity, then this can be witnessed by singletons (in any theory).
On dp-minimal fields  [PDF]
Will Johnson
Mathematics , 2015,
Abstract: We classify dp-minimal pure fields up to elementary equivalence. Most are equivalent to Hahn series fields $K((t^\Gamma))$ where $\Gamma$ satisfies some divisibility conditions and $K$ is $\mathbb{F}_p^{alg}$ or a local field of characteristic zero. We show that dp-small fields (including VC-minimal fields) are algebraically closed or real closed.
Abundances of PNe in the Outer Disk of M31  [PDF]
Karen B. Kwitter,Emma M. M. Lehman,Bruce Balick,R. B. C. Henry
Physics , 2012, DOI: 10.1088/0004-637X/753/1/12
Abstract: We present spectroscopic observations and chemical abundances of 16 planetary nebulae (PNe) in the outer disk of M31. The [O III] 4363 line is detected in all objects, allowing a direct measurement of the nebular temperature essential for accurate abundance determinations. Our results show that the abundances in these M31 PNe display the same correlations and general behaviors as Type II PNe in the Milky Way Galaxy. We also calculate photoionization models to derive estimates of central star properties. From these we infer that our sample PNe, all near the peak of the Planetary Nebula Luminosity Function, originated from stars near 2 M_sun. Finally, under the assumption that these PNe are located in M31's disk, we plot the oxygen abundance gradient, which appears shallower than the gradient in the Milky Way.
Search for binary central stars of the SMC PNe  [PDF]
M. Hajduk,M. Gladkowski,I. Soszyński
Physics , 2013, DOI: 10.1051/0004-6361/201321682
Abstract: The Optical Gravitational Lensing Experiment (OGLE), originally designed to search for microlensing events, provides a rich and uniform data set suitable for studying the variability of certain types of objects. We used the OGLE data to study the photometry of central stars of planetary nebulae (PNe) in the Small Magellanic Cloud (SMC). In particular, we searched for close binary central stars with the aim to constrain the binary fraction and period distribution in the SMC. We also searched for PNe mimics and removed them from the PNe sample. We identified 52 counterparts of PNe in the SMC in the I-band images from the OGLE-II and OGLE-III surveys. We analysed the time-series photometry of the PNe. Spectra of the photometric variables were obtained to constrain the nature of the objects or search for additional evidence for binarity. Eight variables were found. Of these, seven objects are PNe mimics, including one symbiotic star candidate. One close binary central star of PN with a period of 1.15 or 2.31 day was discovered. The obtained binary fraction for the SMC PNe and the observational biases are discussed in terms of the OGLE observations.
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