4,073 research outputs found

    HH 223: a parsec-scale H2 outflow in the star-forming region L723

    Full text link
    The dark cloud Lynds 723 (L723) is a low-mass star-forming region where one of the few known cases of a quadrupolar CO outflow has been reported. Two recent works have found that the radio continuum source VLA 2, towards the centre of the CO outflow, is actually a multiple system of young stellar objects (YSOs). Several line-emission nebulae that lie projected on the east-west CO outflow were detected in narrow-band Halpha and [SII] images. The spectra of the knots are characteristic of shock-excited gas (Herbig-Haro spectra), with supersonic blueshifted velocities, which suggests an optical outflow also powered by the VLA 2 YSO system of L723. We imaged a field of ~5' X 5' centred on HH 223, which includes the whole region of the quadrupolar CO outflow with nir narrow-band filters . The H2 line-emission structures appear distributed over a region of 5.5' (0.5 pc for a distance of 300 pc) at both sides of the VLA 2 YSO system, with an S-shape morphology, and are projected onto the east-west CO outflow. Most of them were resolved in smaller knotty substructures. The [FeII] emission only appears associated with HH 223. An additional nebular emission from the continuum in Hc and Kc appears associated with HH 223-K1, the structure closest to the VLA 2 YSO system, and could be tracing the cavity walls. We propose that the H2 structures form part of a large-scale near-infrared outflow, which is also associated with the VLA 2 YSO system. The current data do not allow us to discern which of the YSOs of VLA 2 is powering this large scale optical/near-infrared outflow.Comment: Accepted for A&A http://dx.doi.org/10.1051/0004-6361/201015125 12 pages, 9 figure

    3-D Photoionization Structure and Distances of Planetary Nebulae IV. NGC 40

    Full text link
    Continuing our series of papers on the 3-D structure and accurate distances of Planetary Nebulae (PNe), we present here the results obtained for the planetary nebula NGC\,40. Using data from different sources and wavelengths, we construct 3-D photoionization models and derive the physical quantitities of the ionizing source and nebular gas. The procedure, discussed in detail in the previous papers, consists of the use of 3-D photoionization codes constrained by observational data to derive the three-dimensional nebular structure, physical and chemical characteristics and ionizing star parameters of the objects by simultaneously fitting the integrated line intensities, the density map, the temperature map, and the observed morphologies in different emission lines. For this particular case we combined hydrodynamical simulations with the photoionization scheme in order to obtain self-consistent distributions of density and velocity of the nebular material. Combining the velocity field with the emission line cubes we also obtained the synthetic position-velocity plots that are compared to the observations. Finally, using theoretical evolutionary tracks of intermediate and low mass stars, we derive the mass and age of the central star of NGC\,40 as (0.567±0.06)(0.567 \pm 0.06)M_{\odot} and (5810±600)(5810 \pm 600)yrs, respectively. The distance obtained from the fitting procedure was (1150±120)(1150 \pm 120)pc.Comment: 12 pages, 11 figures, accepted for publication in Ap

    The L723 low mass star forming protostellar system: resolving a double core

    Full text link
    We present 1.35 mm SMA observations around the low-mass Class 0 source IRAS 19156+1906, at the the center of the L723 dark cloud. We detected emission from dust as well as emission from H2CO, DCN and CN, which arise from two cores, SMA 1 and SMA 2, separated by 2.9" (880 AU). SMA 2 is associated with VLA 2. SiO 5-4 emission is detected, possibly tracing a region of interaction between the dense envelope and the outflow. We modeled the dust and the H2CO emission from the two cores: they have similar physical properties but SMA 2 has a larger p-H2CO abundance than SMA 1. The p-H2CO abundances found are compatible with the value of the outer part of the circumstellar envelopes associated with Class 0 sources. SMA 2 is likely more evolved than SMA 1. The kinematics of the two sources show marginal evidence of infall and rotation motions. The mass detected by the SMA observation, which trace scales of ~1000 AU, is only a small fraction of the mass contained in the large scale molecular envelope, which suggests that L723 is still in a very early phase of star formation. Despite the apparent quiescent nature of the L723, fragmentation is occurring at the center of the cloud at different scales. Thus, at 1000 AU the cloud has fragmented in two cores, SMA 1 and SMA 2. At the same time, at least one of these cores, SMA 2, has undergone additional fragmentation at scales of 150 AU, forming a multiple stellar system.Comment: 35 pages, 15 figures. Accepted to the Astrophysical Journa

    Closing oil palm yield gaps among Indonesian smallholders through industry schemes, pruning, weeding and improved seeds

    Get PDF
    Oil palm production has led to large losses of valuable habitats for tropical biodiversity. Sparing of land for nature could in theory be attained if oil palm yields increased. The efficiency of oil palm smallholders is below its potential capacity, but the factors determining efficiency are poorly understood. We employed a two-stage data envelopment analysis approach to assess the influence of agronomic, supply chain and management factors on oil palm production efficiency in 190 smallholders in six villages in Indonesia. The results show that, on average, yield increases of 65% were possible and that fertilizer and herbicide use was excessive and inefficient. Adopting industry-supported scheme management practices, use of high-quality seeds and higher pruning and weeding rates were found to improve efficiency. Smallholder oil palm production intensification in Indonesia has the capacity to increase production by 26%, an equivalent of 1.75 million hectares of land

    La valoración de la confesión sincera como criterio atenuante en la terminación anticipada frente a la imposición de penas proporcionales

    Get PDF
    La instauración del proceso de Terminación Anticipada dentro de nuestra legislación procesal penal obedece a razones de política criminal que derivan de la verificación del fracaso del uso exclusivo del proceso penal tradicional, el mismo que ha deslegitimado el sistema de administración de justicia debido a su demostrada ineficacia en la resolución de los conflictos jurídicos derivados de la comisión de un delito, conllevando a que la incrementada carga procesal se desborde en los despachos judiciales; por ello con la finalidad de promover un proceso eficaz y simplificado dotado de las garantías constitucionales, el legislador ha planteado la opción de que el imputado concluya anticipadamente el proceso mediante la aceptación de cargos; sin embargo, al analizar su tratamiento legal se puede apreciar que los beneficios premiales conferidos en este proceso especial son extremadamente beneficiosos tornándose desproporcionales, máxime si en la aplicación de este beneficio se valora una institución de carácter procesal como la confesión sincera cuya naturaleza jurídica no puede jamás equipararse a la de una atenuante privilegiada regulada en el Código Penal; de esta manera, resulta necesario establecer criterios objetivos que permitan sustentar que la aplicación de estos beneficios responden a los ideales plasmados en los principios que rigen en el campo de la ciencia jurídico-penal. Así, es conveniente plantear una propuesta de modificación del artículo 471° del Nuevo Código Procesal Penal peruano, optando por inaplicar el beneficio de reducción acumulable, teniendo como único beneficio la reducción de la pena en una sexta parte para aquellos imputados que se acojan a este proceso.The establishment of the Early Termination process within our criminal procedure legislation is due to criminal policy reasons that derive from the verification of the failure of the exclusive use of the traditional criminal process, the same one that has delegitimized the justice administration system due to its proven ineffectiveness. in the resolution of legal conflicts derived from the commission of a crime, leading to the increased procedural burden overflowing in judicial offices; For this reason, with the purpose of promoting an efficient and simplified process endowed with constitutional guarantees, the legislator has raised the option that the accused conclude the process early by accepting charges; However, when analyzing its legal treatment, it can be seen that the reward benefits conferred in this special process are extremely beneficial, becoming disproportionate, especially if in the application of this benefit an institution of a procedural nature is valued, such as a sincere confession whose legal nature cannot never equate to that of a privileged mitigation regulated in the Penal Code; In this way, it is necessary to establish objective criteria that allow sustaining that the application of these benefits respond to the ideals embodied in the principles that govern the field of legal-criminal science. Thus, it is appropriate to propose a proposal to modify article 471 of the New Peruvian Criminal Procedure Code, opting to not apply the cumulative reduction benefit, with the only benefit being the reduction of the sentence by one sixth for those accused who avail themselves of this benefit. proces

    Quasifree Eta Photoproduction from Nuclei

    Full text link
    Quasifree η\eta photoproduction from nuclei is studied in the Distorted Wave Impulse Approximation (DWIA). The elementary eta production operator contains Born terms, vector meson and nucleon resonance contributions and provides an excellent description of the recent low energy Mainz measurements on the nucleon. The resonance sector includes the S11(1535)S_{11}(1535), P11(1440)P_{11}(1440) and D13(1520)D_{13}(1520) states whose couplings are fixed by independent electromagnetic and hadronic data. Different models for the ηN\eta N t-matrix are used to construct a simple ηA\eta A optical potential based on a tρt \rho-approximation. We find that the exclusive A(γ,ηN)BA(\gamma,\eta N)B process can be used to study medium modifications of the NN^* resonances, particularly if the photon asymmetry can be measured. The inclusive A(γ,η)XA(\gamma, \eta)X reaction is compared to new data obtained on 12C^{12}C, 40Ca^{40}Ca, and is found to provide a clear distinction between different models for the ηN\eta N t-matrix.Comment: 30 pages in RevTeX including 14 embedded PS figures; Replaced with revised version. Added more discussion about the imaginary part of the eta optical potentia

    Loss of Notch3 Signaling Enhances Osteogenesis of Mesenchymal Stem Cells from Mandibular Torus

    Get PDF
    Mandibular torus (MT) is a common intraoral osseous outgrowth located on the lingual surface of the mandible. Histologic features include hyperplastic bone consisting of mature cortical and trabecular bone. Some theories on the etiology of MT have been postulated, such as genetic factors, masticatory hyperfunction, trauma, and continued growth, but the underlying mechanism remains largely unknown. In this study, we investigated the potential role of mesenchymal stem cells (MSCs) derived from human MT in the pathogenesis of bone outgrowth. We demonstrated that MT harbored a distinct subpopulation of MSCs, with enhanced osteogenic and decreased adipogenic differentiation capacities, as compared with their counterparts from normal jaw bone. The increased osteogenic differentiation of mandibular torus MSCs was associated with the suppression of Notch3 signaling and its downstream target genes, Jag1 and Hey1, and a reciprocal increase in the transcriptional activation of ATF4 and NFATc1 genes. Targeted knockdown of Notch3 expression by transient siRNA transfection promoted the expression of osteogenic transcription factors in normal jaw bone MSCs. Our data suggest that the loss of Notch3 signaling may contribute partly to bone outgrowth in MT, as mediated by enhanced MSC-driven osteogenic differentiation in the jaw bone. © International & American Associations for Dental Research 2016

    The nature of HH 223 from long-slit spectroscopy

    Full text link
    HH 223 is a knotty, wiggling nebular emission of ~30" length found in the L723 star-forming region. It lies projected onto the largest blueshifted lobe of the cuadrupolar CO outflow powered by a low-mass YSO system embedded in the core of L723. We analysed the physical conditions and kinematics along HH 223 with the aim of disentangling whether the emission arises from shock-excited, supersonic gas characteristic of a stellar jet, or is only tracing the wall cavity excavated by the CO outflow. We performed long-slit optical spectroscopy along HH 223, crossing all the bright knots (A to E) and part of the low-brightness emission nebula (F filament). One spectrum of each knot, suitable to characterize the nature of its emission, was obtained. The physical conditions and the radial velocity of the HH 223 emission along the slits were also sampled at smaller scale (0.6") than the knot sizes. {The spectra of all the HH 223 knots appear as those of the intermediate/high excitation Herbig-Haro objects. The emission is supersonic, with blueshifted peak velocities ranging from -60 to -130 km/s. Reliable variations in the kinematics and physical conditions at smaller scale that the knot sizes are also found. The properties of the HH 223 emission derived from the spectroscopy confirm the HH nature of the object, the supersonic optical outflow most probably also being powered by the YSOs embedded in the L723 core.Comment: A&A accepte
    corecore