A search for new hot subdwarf stars by means of Virtual Observatory tools

Hot subdwarf stars are faint, blue objects, and are the main contributors to the far-UV excess observed in elliptical galaxies. They offer an excellent laboratory to study close and wide binary systems, and to scrutinize their interiors through asteroseismology, as some of them undergo stellar oscillations. However, their origins are still uncertain, and increasing the number of detections is crucial to undertake statistical studies. In this work, we aim at defining a strategy to find new, uncatalogued hot subdwarfs. Making use of Virtual Observatory tools we thoroughly search stellar catalogues to retrieve multi-colour photometry and astrometric information of a known sample of blue objects, including hot subdwarfs, white dwarfs, cataclysmic variables and main sequence OB stars. We define a procedure to discriminate among these spectral classes, particularly designed to obtain a hot subdwarf sample with a low contamination factor. In order to check the validity of the method, this procedure is then applied to two test sky regions: the Kepler FoV and to a test region of around (RA:225, DEC:5) deg. As a result, we obtained 38 hot subdwarf candidates, 23 of which had already a spectral classification. We have acquired spectroscopy for three other targets, and four additional ones have an available SDSS spectrum, which we used to determine their spectral type. A temperature estimate is provided for the candidates based on their spectral energy distribution, considering two-atmospheres fit for objects with clear infrared excess. Eventually, out of 30 candidates with spectral classification, 26 objects were confirmed to be hot subdwarfs, yielding a contamination factor of only 13%. The high rate of success demonstrates the validity of the proposed strategy to find new uncatalogued hot subdwarfs. An application of this method to the entire sky will be presented in a forthcoming work.Comment: 13 pages, 7 figure

The Phosphorylation and Distribution of Cortactin Downstream of Integrin α9β1 Affects Cancer Cell Behaviour

Integrins, a family of heterodimeric adhesion receptors are implicated in cell migration, development and cancer progression. They can adopt conformations that reflect their activation states and thereby impact adhesion strength and migration. Integrins in an intermediate activation state may be optimal for migration and we have shown previously that fully activated integrin α9β1 corresponds with less migratory behaviour in melanoma cells. Here, we aimed to identify components associated with the activation status of α9β1. Using cancer cell lines with naturally occuring high levels of this integrin, activation by α9β1-specific ligands led to upregulation of fibronectin matrix assembly and tyrosine phosphorylation of cortactin on tyrosine 470 (Y470). Specifically, cortactin phosphorylated on Y470, but not Y421, redistributed together with α9β1 to focal adhesions where active β1 integrin also localises, upon integrin activation. This was commensurate with reduced migration. The localisation and phosphorylation of cortactin Y470 was regulated by Yes kinase and PTEN phosphatase. Cortactin levels influenced fibronectin matrix assembly and active β1 integrin on the cell surface, being inversely correlated with migratory behaviour. This study underlines the complex interplay between cortactin and α9β1 integrin that regulates cell-extracellular matrix interactions

Detection of a multi-shell planetary nebula around the hot subdwarf O-type star 2MASS J19310888+4324577

(Abridged) The origin of hot subdwarf O-type stars (sdOs) remains unclear since their discovery in 1947. Among others, a post-Asymptotic Giant Branch (post-AGB) origin is possible for a fraction of sdOs. We are involved in a comprehensive ongoing study to search for and to analyze planetary nebulae (PNe) around sdOs with the aim of establishing the fraction and properties of sdOs with a post-AGB origin. We use deep Halpha and [OIII] images of sdOs to detect nebular emission and intermediate resolution, long-slit optical spectroscopy of the detected nebulae and their sdO central stars. These data are complemented with other observations for further analysis of the detected nebulae. We report the detection of an extremely faint, complex PN around 2MASS J19310888+4324577 (2M1931+4324), a star classified as sdO in a binary system. The PN shows a bipolar and an elliptical shell, whose major axes are oriented perpendicular to each other, and high-excitation structures outside the two shells. WISE archive images show faint, extended emission at 12 and 22 microns in the inner nebular regions. The internal nebular kinematics is consistent with a bipolar and a cylindrical/ellipsoidal shell, in both cases with the main axis mainly perpendicular to the line of sight. The nebular spectrum only exhibits Halpha, Hbeta and [OIII]4959,5007 emission lines, but suggests a very low-excitation ([OIII]/Hbeta = 1.5), in strong contrast with the absence of low-excitation emission lines. The spectrum of 2M1931+4324 presents narrow, ionized helium absorptions that confirm the previous sdO classification and suggest an effective temperature >= 60000 K. The binary nature of 2M1931+4324, its association with a complex PN, and several properties of the system provide strong support for the idea that binary central stars are a crucial ingredient in the formation of complex PNe.Comment: 8 pages, 7 figures, accepted in Astronomy and Astrophysic

Pengembangan Sistem Pendeteksi Kemiripan Karya pada Inaicta 2013

Indonesia  ICT  Award  (INAICTA)  2013  merupakan  ajang  lomba  karya  cipta  kreativitas  dan  inovasi  di bidang TIK (Teknologi Informasi dan Komputer) terbesar di Indonesia yang bertujuan untuk terus mendorong berkembangnya  produk-produk  TIK  (Teknologi  Informasi  dan  Komputer)  lokal  dengan  peningkatan  kualitas maupun inovasi produk. Semakin tahun, jumlah kontestan yang mengikuti INAICTA semakin bertambah. Hal tersebut berpengaruh terhadap tingkat kesulitan bagi para juri atau tim penilai untuk mengetahui kemiripan dari inovasi-inovasi para kontestan. Dibutuhkan suatu aplikasi yang dapat membantu dalam pendeteksian kemiripan tiap  hasil  karya  yang  diikutsertakan  oleh  para  kontestan.  Oleh  karena  itu  dilakukan  pengembangan  sistem pendeteksi  kemiripan  karya  pada  INAICTA  2013  dengan  membandingkan  penjelasan  ringkas karya para kontestan.  Dalam  pengembangan  sistem  pendeteksi  ini  menggunakan  Algoritma Term  Frequency– Inversed Document  Frequency (TF-IDF)  untuk  proses  pembobotan  karya.  Dengan TF-IDF sistem  akan  menghitung berdasarkan term pada  setiap  karya.  Sedangkan  untuk  melihat  tingkat  kedekatan  atau  kesamaan (similarity) karya,  sistem  ini  menggunakan  Algortitma Vector  Space  Model (VSM).  Dengan VSM data  karya  dipandang sebagai  sebuah  vektor  yang  memiliki magnitude (jarak)  dan direction  (arah).  Sehingga  sistem  pendeteksi kemiripan karya pada INAICTA 2013 ini akan menghasilkan urutan tingkat kemiripan karya INAICTA 2013

Development of the CoMac Adherence Descriptor™: a linguistically-based survey for segmenting patients on their worldviews

Nonadherence to prescribed medication and healthy behaviors is a pressing health care issue. Much research has been conducted in this area under a variety of labels, such as compliance, disease management and, most recently, adherence. However, the complex factors related to predicting and, more importantly, understanding and explaining adherence, have nevertheless remained elusive. However, through an in-depth linguistic analysis of patient talk, the International Center for Intercultural Communication (ICIC) at Indiana University has produced a psycholinguistic coding system that uses patients' own language to cluster them into distinct groups based on their worldviews. ICIC's studies have shown, for example, that patients reveal their fundamental perceptions about themselves and their environment in their life narratives; clustering of individual patients based on these different perceptions is possible via the use of differential language in survey questions, and differential language can be used to tailor messages for individual patients in a manner that these individuals prefer over generically worded communication. In grant-funded research, an interdisciplinary team of researchers at the ICIC reviewed the literature and identified three basic psychosocial tenets related to adherence: control orientation, based on locus of control research; agency, based on self-efficacy; and affect or attitude and emotion. These three constructs were selected because, in the published literature, they have been consistently found to be connected to patient adherence. Based on this research, a survey, the CoMac Descriptor™ was developed. This report shows that The Descriptor™ questions and responses are valid and reliable in segmenting patients across psychosocial constructs, which will have positive implications for health care providers and patients

CCD-based observations of PG 0856+121 and a theoretical analysis of its oscillation modes

BVRI CCD-based and near-IR (J) imaging, together with unfiltered photometry of the hot subdwarf B star PG 0856+121 are reported. Two close, faint, red, point-like sources are resolved. They account for the previously reported IR excess observed in this hot subdwarf. In addition, the new unfiltered differential photometry of PG 0856+121 confirms its previously reported pulsational nature. A comparison with the oscillation modes of stellar models suggests the possible presence of g modes.Comment: Accepted for publication in A&A. Seven pages, four figures include

The Formation of Cataclysmic Variables with Brown Dwarf Secondaries

The present-day formation of cataclysmic variables (CVs) with brown dwarf (BD) secondaries (0.013 M_sun < M_sec < 0.075 M_sun) is investigated using a population synthesis technique. Results from the latest, detailed models for BDs have been incorporated into the population synthesis code. For our models, we find that ZACVs with BD secondaries have orbital periods in the range 46 min to 2.5 hrs. We also find that ZACVs with BD secondaries comprise 18% of the total, present-day ZACV population. In addition, we find that 80% of ZACVs with BD secondaries have orbital periods < 78 minutes. This implies that 15% of the present-day ZACV population should have orbital periods shorter than the observed orbital period minimum for CVs. We also investigate the dependence of the present-day formation rate of CVs with BD secondaries on the assumed value of the common envelope efficiency parameter, alpha_CE, for three different assumed mass ratio distributions in ZAMS binaries. Surprisingly, we find that the common envelope process must be extremely inefficient (alpha_CE < 0.1) in order for CVs with BD secondaries not to be formed. Finally, we find that the progenitor binaries of ZACVs with BD secondaries have ZAMS orbital separations < 3 AU and ZAMS primary masses between ~1-10 M_sun, with ~75% of the primary masses less than ~1.6 M_sun. Interestingly, these ranges in orbital separation and primary mass place the majority of the progenitor binaries within the so-called ``brown dwarf desert.''Comment: preprint 27 pages 4 figures; to appear in ApJ April 1, 200

Lipid mediators in platelet concentrate and extracellular vesicles: Molecular mechanisms from membrane glycerophospholipids to bioactive molecules

Platelets are collected for transfusion to patients with different hematological disorders, and for logistical reasons, platelets are stored as concentrates. Despite the carefully controlled conditions, platelets become activated during storage, and platelet concentrates (PLCs) may cause adverse inflammatory reactions in the recipients. We studied by mass spectrometry the lipidomic changes during storage of the clinical PLCs, the platelets isolated from PLCs, and the extracellular vesicles (EVs) thereof. The release of EVs from platelets increased with the prolonged storage time. The molar percentages of arachidonic acid -containing species were increased during storage especially in the phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine classes of glycerophopholipids. The increase of these species in the membrane glycerophopholipid composition paralleled the production of both proinflammatory and proresolving lipid mediators (LMs) as the amount of the arachidonic acid-derived LMs such as thromboxane B2 and prostaglandin E2 also increased in time. Moreover, several monohydroxy pathway markers and functionally relevant proinflammatory and proresolving LMs were detected in the PLC and the EVs, and some of these clearly accumulated during storage. By Western blot, the key enzymes of these pathways were shown to be present in the platelets and in many cases also in the EVs. Since the EVs were enriched in the fatty acid precursors of LMs, harbored LM-producing enzymes, contained the related monohydroxy pathway markers, and also secreted the final LM products, the PLC-derived EVs appear to have the potential to regulate inflammation and healing, and may thereby aid the platelets in exerting their essential physiological functions.Peer reviewe

Observations of the pulsating subdwarf B star Feige 48: Constraints on evolution and companions

Since pulsating subdwarf B (sdBV or EC14026) stars were first discovered (Kilkenny et al, 1997), observational efforts have tried to realize their potential for constraining the interior physics of extreme horizontal branch (EHB) stars. Difficulties encountered along the way include uncertain mode identifications and a lack of stable pulsation mode properties. Here we report on Feige 48, an sdBV star for which follow-up observations have been obtained spanning more than four years, which shows some stable pulsation modes. We resolve the temporal spectrum into five stable pulsation periods in the range 340 to 380 seconds with amplitudes less than 1%, and two additional periods that appear in one dataset each. The three largest amplitude periodicities are nearly equally spaced, and we explore the consequences of identifying them as a rotationally split l=1 triplet by consulting with a representative stellar model. The general stability of the pulsation amplitudes and phases allows us to use the pulsation phases to constrain the timescale of evolution for this sdBV star. Additionally, we are able to place interesting limits on any stellar or planetary companion to Feige 48.Comment: accepted for publication in MNRA