A Keplerian gaseous disk around the B0 star R Mon

We present high-angular resolution observations of the circumstellar disk around the massive Herbig Be star R Mon (M~8 Msun) in the continuum at 2.7mm and 1.3mm and the CO 1->0 and 2->1 rotational lines. Based on the new 1.3mm continuum image we estimate a disk mass (gas+dust) of 0.007 Msun and an outer radius of <150 AU. Our CO images are consistent with the existence of a Keplerian rotating gaseous disk around this star. Up to our knowledge, this is the most clear evidence for the existence of Keplerian disks around massive stars reported thus far. The mass and physical characteristics of this disk are similar to thoseof the more evolved T Tauri stars and indicate a shorter timescale for the evolution and dispersal of circumstellar disks around massive stars which lose most of their mass before the star becomes visible.Comment: 5 page

Pengelompokan Tim Pengembang Berdasarkan Kriteria Perilaku Manusia dalam Kolaborasi Pengembangan Perangkat Lunak

Teknologi informasi merupakan bidang yang berkembang cukup pesat di akhir dekade ini. Hal tersebut ditandai dengan meningkatnya kebutuhan akan teknologi informasi. Salah satu bagian dari proyek teknologi informasi yang berkembang cukup pesat adalah proyek pengembangan perangkat lunak yang mempunyai ketidakpastian tinggi dengan tingkat kesuksesan yang rendah. Kualitas dan kecepatan proyek perangkat lunak sangat tergantung pada faktor sumber daya manusia. Tujuan penelitian ini adalah untuk mengembangkan sebuah strategi dan kriteria dengan mengelompokkan perilaku tim pengembang sehingga metode kolaborasi yang akan dilakukan dapat disesuaikan dengan susunan tim yang terlibat dalam pengembangan perangkat lunak. Pengelompokan perilaku programmer dalam kolaborasi tim pengembang perangkat lunak dilakukan dengan menggunakan analisis kluster dengan melihat lima variabel, yaitu usia, gender, interaksi dan komunikasi, kondisi psikologis, dan pemrosesan informasi. Pengujian diambil dari 35 programmer yang berasal dari industri perangkat lunak yang terdapat di Bandung dengan menyebar kuisioner pada tim pengembang secara online maupun offline. Hasil pengolahan data dengan software SPSS menunjukkan bahwa terdapat tiga kluster perilaku programmer dalam kolaborasi tim pengembangan perangkat lunak. Dengan diketahuinya pengelompokan perilaku programmer diharapkan tim pengembang yang dibentuk dapat menghasilkan perangkat lunak dengan kualitas yang lebih baik

The dusty disk around VV Ser

We have carried out observations at millimeter and centimeter wavelengths towards VV Ser using the Plateau de Bure Interferometer and the Very Large Array. This allows us to compute the SED from near infrared to centimeter wavelengths. The modeling of the full SED has provided insight into the dust properties and a more accurate value of the disk mass. The mass of dust in the disk around VV Ser is found to be about 4 10^(-5) Msun, i.e. 400 times larger than previous estimates. Moreoever, the SED can only be accounted for assuming dust stratification in the vertical direction across the disk. The existence of small grains (0.25--1 micron) in the disk surface is required to explain the emission at near- and mid-infrared wavelengths. The fluxes measured at millimeter wavelengths imply that the dust grains in the midplane have grown up to very large sizes, at least to some centimeters.Comment: To appear in Ap

Massive young disks around Herbig Ae stars

Herbig Ae stars (HAe) are the precursors of Vega-type systems and, therefore, crucial objects in planet formation studies. Thus far, only a few disks associated with HAe stars have been studied using millimetre interferometers. Our aim is to determine the dust evolution and the lifetime of the disks associated with Herbig Ae stars. We imaged the continuum emission at 3 mm and 1.3 mm of the Herbig Ae/Be stars BD+61154, RR Tau, VY Mon and LkHa 198 using the Plateau de Bure Interferometer (PdBI). These stars are in the upper end of the stellar mass range of the Herbig Ae stars (stellar mass greater than 3 solar masses). Our measurements were used to complete the Spectral Energy Distribution (SED). The modelling of the SED, in particular the FIR-mm part, allow us to determine the masses and dust properties of these disks. We detected the disks associated with BD+61154, RR Tau and VY Mon with disk masses of 0.35 Msun, 0.05 Msun and 0.40 Msun respectively. The disk around LkHa 198 was not detected with an upper limit to the disk mass of 0.004 Msun. We detected, however, the disks associated with the younger stellar objects LkHa 198--IR and LkHa 198-mm that are located in the vicinity of LkHa 198. The fitting of the mm part of the SED reveal that the grains in the mid-plane of the disks around BD+61154, RR Tau and VY Mon have sizes of 1--1000 microns. Therefore, grains have not grown to centimetre sizes in these disks yet. These massive (M>3 Msun) and young (about 1 Myr) HAe stars are surrounded by massive (>0.04 Msun) disks with grains of micron-millimetre sizes. Although grain growth is proceeding in these disks, their evolutionary stage is prior to the formation of planetesimals. These disks are less evolved than those detected around T Tauri and Herbig Be stars

Dissecting an intermediate-mass (IM) protostar: Chemical differentiation in IC1396N

We have carried out high-angular resolution (1.4") observations in the continuum at 3.1mm and in the N2H+ 1-0, CH3CN 5_k-4_k and 13CS 2-1 lines using the Plateau de Bure Interferometer (PdBI) towards the intermediate mass (IM) protostar IRAS21391+5802 (IC1396N). In addition, we have merged the PdBI images with previous BIMA (continuum data at 1.2mm and 3.1mm) and single-dish (N2H+ 1-0) data to have a comprehensive description of the region. The combination of our data with BIMA and 30m data show that the bipolar outflow associated has completely eroded the initial molecular globule. The 1.2mm and 3.1mm continuum emissions are extended along the outflow axis tracing the warm walls of the biconical cavity. Most of the molecular gas, however, is located in an elongated feature in the direction perpendicular to the outflow. A strong chemical differentiation is detected across the molecular toroid, with the N2H+ 1-0 emission absent in the inner region.This chemical differentiation can be understood in terms of the different gas kinetic temperature. The [CH3CN]/[N2H+] ratio increases by 5 orders of magnitude with gas temperature, for temperatures between 20K and 100K. The CH3CN abundance towards IRAM 2A, the most massive protostellar core, is similar to that found in hot corinos and lower than that expected towards IM and high mass hot cores. This could indicate that IRAM 2A is a low mass or at most Herbig Ae star (IRAM 2A) instead of the precursor of a massive Be star. Alternatively, the low CH3CN abundance could also be the consequence of IRAM 2A being a Class 0/I transition object which has already formed a small photodissociation region (PDR).Comment: accepted A&

Spaceflight Induced Disorders: Potential Nutritional Countermeasures

Space travel is an extreme experience even for the astronaut who has received extensive basic training in various fields, from aeronautics to engineering, from medicine to physics and biology. Microgravity puts a strain on members of space crews, both physically and mentally: short-term or long-term travel in orbit the International Space Station may have serious repercussions on the human body, which may undergo physiological changes affecting almost all organs and systems, particularly at the muscular, cardiovascular and bone compartments. This review aims to highlight recent studies describing damages of human body induced by the space environment for microgravity, and radiation. All novel conditions, to ally unknown to the Darwinian selection strategies on Earth, to which we should add the psychological stress that astronauts suffer due to the inevitable forced cohabitation in claustrophobic environments, the deprivation from their affections and the need to adapt to a new lifestyle with molecular changes due to the confinement. In this context, significant nutritional deficiencies with consequent molecular mechanism changes in the cells that induce to the onset of physiological and cognitive impairment have been considered

Componente del insaponificable del aceite de oliva con polaridad comprendida entre el escualeno y los alcoholes triterpénicos

In the unsaponifiable matter of refined olive oils and, frequently, virgin olive oils of bad quality, a new compound with polarity between those of squalene and triterpenic alcohols was isolated. Mass spectrometry of this compound and of their hydrogenated and; sililated derivatives, demonstrated that the compound was a long chain alcohol having 426 of molecular weight, polyisoprenic structure similar to that of squalene, and the hydroxyl group attached at the C-2 carbon atom.Se ha estudiado y determinado la estructura de un compuesto, de polaridad comprendida entre el escualeno y los alcoholes triterpénicos, que se encuentra en el insaponificable de los aceites de oliva refinados y en muchas ocasiones en el de los vírgenes, sobre todo en los de baja calidad. La espectrometría de masas del mismo y, de sus derivados hidrogenado y sililado, ha puesto de manifiesto que se trata de un alcohol triterpénico lineal, de peso molecular 426, con el esqueleto similar al del escualeno y con el grupo hidroxilo en posición 2

Aislamiento y cuantificación de los componentes de la hoja del olivo: extracto de hexano

The principal components of the hexane extract from olive leaves are analysed, following an analytical procedure based on the extraction with hexane and the later separation of groups of compounds, according to their polarity, by means of column and thin-layer chromatographies. The following components are separated and identified: hydrocarbons, ester waxes, triglycerides, tocopherols, esterols, lineal and terpenic alcohols and terpenic dialcohols. The olive leaves from five different varieties were analyzed: Picual, Arbequina, Hojiblanca, Empeltre and Cornicabra; the concentration of some compounds ranged between: 2.057-3.400 ppm saturated hydrocarbons; 38-152 ppm squalene; 915-1.874 ppm ester waxes; 28-100 ppm β-carotene; 832-1.396 ppm triglycerides; 41-125 ppm α-tocopherol; 614-2.500 ppm β-sitosterol; 95-311 ppm alcohols and 342-837 ppm terpenic dialcohols.Se analizan los principales componentes del extracto de hexano de hojas de olivo, siguiendo un esquema analítico basado en la extracción con hexano y posterior separación de grupos de compuestos, según su polaridad, mediante cromatografía en columna y en capa fina. Se separan e identifican los siguientes componentes: hidrocarburos, ceras ésteres, triglicéridos, tocoferoles, esteroles, alcoholes lineales y terpénicos y dialcoholes terpénicos. Se han estudiado las hojas de olivo de cinco variedades: Picual, Arbequina Hojiblanca, Empeltre y Cornicabra, los rangos del contenido, en ppm, de algunos compuestos resultaron: hidrocarburos saturados, 2.057-3.400; escualeno, 38-152; ceras ésteres, 915-1874; β -caroteno, 28-100; triglicéridos, 832-1.396; α -tocoferol, 41-125; β-sitosterol, 714-2.500 alcoholes totales 95-311 y dialcoholes terpénicos, 342-837

Protostellar clusters in intermediate-mass (IM) star forming regions

The transition between the low density groups of T Tauri stars and the high density clusters around massive stars occurs in the intermediate-mass (IM) range (M$_*$$\sim$2--8 M$_\odot$). High spatial resolution studies of IM young stellar objects (YSO) can provide important clues to understand the clustering in massive star forming regions. Aims: Our aim is to search for clustering in IM Class 0 protostars. The high spatial resolution and sensitivity provided by the new A configuration of the Plateau de Bure Interferometer (PdBI) allow us to study the clustering in these nearby objects. Methods: We have imaged three IM Class 0 protostars (Serpens-FIRS 1, IC 1396 N, CB 3) in the continuum at 3.3 and 1.3mm using the PdBI. The sources have been selected with different luminosity to investigate the dependence of the clustering process on the luminosity of the source. Results: Only one millimeter (mm) source is detected towards the low luminosity source Serpens--FIRS 1. Towards CB 3 and IC1396 N, we detect two compact sources separated by $\sim$0.05 pc. The 1.3mm image of IC 1396 N, which provides the highest spatial resolution, reveal that one of these cores is splitted in, at least, three individual sources.Comment: 4 pages, 3 figures, accepted for publication in Astronomy and Astrophysics Letters (Special Feature IRAM/PdB