The Sentinel-2 program provides the opportunity to monitor terrestrial ecosystems with a high temporal and spectral resolution. In this study, a multi-temporal Sentinel-2 data set was used to ...classify common tree species over a mature forest in central Sweden. The tree species to be classified were Norway spruce (Picea abies), Scots pine (Pinus silvestris), Hybrid larch (Larix × marschlinsii), Birch (Betula sp.) and Pedunculate oak (Quercus robur). Four Sentinel-2 images from spring (7 April and 27 May), summer (9 July) and fall (19 October) of 2017 were used along with the Random Forest (RF) classifier. A variable selection approach was implemented to find fewer and uncorrelated bands resulting in the best model for tree species identification. The final model resulting in the highest overall accuracy (88.2%) came from using all bands from the four image dates. The single image that gave the most accurate classification result (80.5%) was the late spring image (27 May); the 27 May image was always included in subsequent image combinations that gave the highest overall accuracy. The five tree species were classified with a user’s accuracy ranging from 70.9% to 95.6%. Thirteen of the 40 bands were selected in a variable selection procedure and resulted in a model with only slightly lower accuracy (86.3%) than that using all bands. Among the highest ranked bands were the red edge bands 2 and 3 as well as the narrow NIR (near-infrared) band 8a, all from the 27 May image, and SWIR (short-wave infrared) bands from all four image dates. This study shows that the red-edge bands and SWIR bands from Sentinel-2 are of importance, and confirms that spring and/or fall images capturing phenological differences between the species are most useful to tree species classification.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
astroquery is a collection of tools for requesting data from databases hosted on remote servers with interfaces exposed on the internet, including those with web pages but without formal application ...program interfaces. These tools are built on the Python requests package, which is used to make HTTP requests, and astropy, which provides most of the data parsing functionality. astroquery modules generally attempt to replicate the web page interface provided by a given service as closely as possible, making the transition from browser-based to command-line interaction easy. astroquery has received significant contributions from throughout the astronomical community, including several from telescope archives. astroquery enables the creation of fully reproducible workflows from data acquisition through publication. This paper describes the philosophy, basic structure, and development model of the astroquery package. The complete documentation for astroquery can be found at http://astroquery.readthedocs.io/.
We have conducted a survey of 328 protostars in the Orion molecular clouds with the Atacama Large Millimeter/submillimeter Array at 0.87 mm at a resolution of ∼0 1 (40 au), including observations ...with the Very Large Array at 9 mm toward 148 protostars at a resolution of ∼0 08 (32 au). This is the largest multiwavelength survey of protostars at this resolution by an order of magnitude. We use the dust continuum emission at 0.87 and 9 mm to measure the dust disk radii and masses toward the Class 0, Class I, and flat-spectrum protostars, characterizing the evolution of these disk properties in the protostellar phase. The mean dust disk radii for the Class 0, Class I, and flat-spectrum protostars are , , and au, respectively, and the mean protostellar dust disk masses are 25.9 , , , respectively. The decrease in dust disk masses is expected from disk evolution and accretion, but the decrease in disk radii may point to the initial conditions of star formation not leading to the systematic growth of disk radii or that radial drift is keeping the dust disk sizes small. At least 146 protostellar disks (35% of 379 detected 0.87 mm continuum sources plus 42 nondetections) have disk radii greater than 50 au in our sample. These properties are not found to vary significantly between different regions within Orion. The protostellar dust disk mass distributions are systematically larger than those of Class II disks by a factor of >4, providing evidence that the cores of giant planets may need to at least begin their formation during the protostellar phase.
Context. The relationship between outflow launching and the formation of accretion disks around young stellar objects is still not entirely understood, which is why spectrally and spatially resolved ...observations are needed. Recently, the Atacama Large Millimetre/sub-millimetre Array (ALMA) carried out long-baseline observations towards a handful of young sources, revealing connections between outflows and the inner regions of disks. Aims. Here we aim to determine the small-scale kinematical and morphological properties of the outflow from the isolated protostar B335 for which no Keplerian disk has, so far, been observed on scales down to 10 au. Methods. We used ALMA in its longest-baseline configuration to observe emission from CO isotopologues, SiO, SO2, and CH3OH. The proximity of B335 provides a resolution of ~3 au (0.03′′). We also combined our long-baseline data with archival observations to produce a high-fidelity image covering scales up to 700 au (7′′). Results. 12CO has an X-shaped morphology with arms ~50 au in width that we associate with the walls of an outflow cavity, similar to what is observed on larger scales. Long-baseline continuum emission is confined to <7 au from the protostar, while short-baseline continuum emission follows the 12CO outflow and cavity walls. Methanol is detected within ~30 au of the protostar. SiO is also detected in the vicinity of the protostar, but extended along the outflow. Conclusions. The 12CO outflow does not show any clear signs of rotation at distances ≳30 au from the protostar. SiO traces the protostellar jet on small scales, but without obvious rotation. CH3OH and SO2 trace a region <16 au in diameter, centred on the continuum peak, which is clearly rotating. Using episodic, high-velocity, 12CO features, we estimate the launching radius of the outflow to be <0.1 au and dynamical timescales of the order of a few years.
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Abstract
The evolutionary past of our Solar system can be pieced together by comparing analogous low-mass protostars with remnants of our Protosolar Nebula – comets. Sulphur-bearing molecules may be ...unique tracers of the joint evolution of the volatile and refractory components. ALMA Band 7 data from the large unbiased Protostellar Interferometric Line Survey are used to search for S-bearing molecules in the outer disc-like structure, ∼60 au from IRAS 16293–2422 B, and are compared with data on 67P/Churyumov–Gerasimenko (67P/C–G) stemming from the ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) instrument aboard Rosetta. Species such as SO2, SO, OCS, CS, H2CS, H2S, and CH3SH are detected via at least one of their isotopologues towards IRAS 16293–2422 B. The search reveals a first-time detection of OC33S towards this source and a tentative first-time detection of C36S towards a low-mass protostar. The data show that IRAS 16293–2422 B contains much more OCS than H2S in comparison to 67P/C–G; meanwhile, the SO/SO2 ratio is in close agreement between the two targets. IRAS 16293–2422 B has a CH3SH/H2CS ratio in range of that of our Solar system (differences by a factor of 0.7–5.3). It is suggested that the levels of UV radiation during the initial collapse of the systems may have varied and have potentially been higher for IRAS 16293–2422 B due to its binary nature; thereby, converting more H2S into OCS. It remains to be conclusively tested if this also promotes the formation of S-bearing complex organics. Elevated UV levels of IRAS 16293–2422 B and a warmer birth cloud of our Solar system may jointly explain the variations between the two low-mass systems.
Lack of conceptual clarity and measurement methods have led to underdeveloped efforts to measure experience of participation in care by next of kin to older people in nursing homes.
We sought to ...assess the measurement properties of items aimed at operationalizing participation in care by next of kin, applied in nursing homes.
A total of 37 items operationalizing participation were administered via a questionnaire to 364 next of kin of older people in nursing homes. Measurement properties were tested with factor analysis and Rasch model analysis.
The response rate to the questionnaire was 81% (n = 260). Missing responses per item varied between <0.5% and 10%. The 37 items were found to be two-dimensional, and 19 were deleted based on conceptual reasoning and Rasch model analysis. One dimension measured communication and trust (nine items, reliability 0.87) while the other measured collaboration in care (nine items, reliability 0.91). Items successfully operationalized a quantitative continuum from lower to higher degrees of participation, and were found to generally fit well with the Rasch model requirements, without disordered thresholds or differential item functioning. Total scores could be calculated based on the bifactor subscale structure (reliability 0.92). Older people (≥ 65 years) reported a higher degree of communication and trust and bifactor total scores than younger people (p < 0.05 in both cases). People with a specific contact person experienced a higher degree of participation in the two subscales and the bifactor total score (p < 0.05 in all three instances).
Psychometric properties revealed satisfactory support for use, in nursing home settings, of the self-reported Next of Kin Participation in Care questionnaire, with a bifactor structure. Additional research is needed to evaluate the effectiveness of the scales' abilities to identify changes after intervention.
The KUPA project has Clinical Trials number NCT02708498.
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III-V vertical nanowire MOSFETs (VNW-FETs) have the potential to extend Moore's law owing to their excellent material properties. To integrate highly scaled memory cells coupled with high performance ...selectors at minimal memory cell area, it is attractive to integrate low-power resistive random access memory (RRAM) cells directly on to III-V VNW-FETs. In this work, we report the experimental demonstration of successful RRAM integration with III-V VNW-FETs. The combined use of VNW-FET drain metal electrode and the RRAM bottom electrode reduces the process complexity and maintains material compatibility. The vertical nanowire geometry allows the RRAM cell area to be aggressively scaled down to 0.01 μm2 enabling realization of dense memory (1T1R) cross-point arrays on silicon.
Context.
Far infrared cooling of excited gas around protostars has been predominantly studied in the context of pointed observations. Large-scale spectral maps of star forming regions enable the ...simultaneous, comparative study of the gas excitation around an ensemble of sources at a common frame of reference, therefore, providing direct insights in the multitude of physical processes involved.
Aims.
We employ extended spectral-line maps to decipher the excitation, the kinematical, and dynamical processes in NGC 1333 as revealed by a number of different molecular and atomic lines, aiming to set a reference for the applicability and limitations of different tracers in constraining particular physical processes.
Methods.
We reconstructed line maps for H
2
, CO, H
2
O, and C
I
using data obtained with the
Spitzer
infrared spectrograph and the
Herschel
HIFI and SPIRE instruments. We compared the morphological features revealed in the maps and derive the gas excitation conditions for regions of interest employing local thermodynamic equilibrium (LTE) and non-LTE methods. We also calculated the kinematical and dynamical properties for each outflow tracer in a consistent manner for all observed outflows driven by protostars in NGC 1333. We finally measured the water abundance in outflows with respect to carbon monoxide and molecular hydrogen.
Results.
CO and H
2
are highly excited around B-stars and, at lower, levels trace protostellar outflows. H
2
O emission is dominated by a moderately fast component associated with outflows. H
2
O also displays a weak, narrow-line component in the vicinity of B-stars associated to their ultraviolet (UV) field. This narrow component is also present in a few of outflows, indicating UV radiation generated in shocks. Intermediate J CO lines appear brightest at the locations traced by the narrow H
2
O component, indicating that beyond the dominating collisional processes, a secondary, radiative excitation component can also be active. The morphology, kinematics, excitation, and abundance variations of water are consistent with its excitation and partial dissociation in shocks. Water abundance ranges between 5 × 10
−7
and ~10
−5
, with the lower values being more representative. Water is brightest and most abundant around IRAS 4A, which is consistent with the latter hosting a hot corino source. C
I
traces dense and warm gas in the envelopes surrounding protostars. Outflow mass flux is highest for CO and decreases by one and two orders of magnitude for H
2
and H
2
O, respectively.
Conclusions.
Large-scale spectral line maps can provide unique insights into the excitation of gas in star-forming regions. A comparative analysis of line excitation and morphologies at different locations allows us to decipher the dominant excitation conditions in each region in addition to isolating exceptional cases.
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