scholarly journals A geostatistical analysis of multiscale metallicity variations in galaxies [I]: Introduction and comparison of high-resolution metallicity maps to an analytic metal transport model

2021 ◽  
Author(s):  
Benjamin Metha ◽  
Michele Trenti ◽  
Tingjin Chu
Keyword(s):  
Large Scale ◽  
Transport Model ◽  
Small Scale ◽  
H Ii Regions ◽  
Integral Field Spectroscopy ◽  
Physical Scale ◽  
Interstellar Media ◽  
Nearby Galaxies ◽  
The Mean ◽  
Linear Regressions

Abstract Thanks to recent advances in integral field spectroscopy (IFS), modern surveys of nearby galaxies are capable of resolving metallicity maps of H ii regions down to scales of ∼50pc. However, statistical analysis of these metallicity maps has seldom gone beyond fitting basic linear regressions and comparing parameters to global galaxy properties. In this paper (the first of a series), we introduce techniques from spatial statistics that are well suited for detailed analysis of both small- and large-scale metallicity variations within the interstellar media (ISMs) of local galaxies. As a first application, we compare the observed structure of small-scale metallicity fluctuations within 7 local galaxies observed by the PHANGS collaboration to predictions from a stochastic, physically motivated, analytical model developed by Krumholz & Ting. We show that while the theoretical model underestimates the amount of correlated scatter in the galactic metallicity distributions by 3 − 4 orders of magnitude, it provides good estimates of the physical scale of metallicity correlations. We conclude that the ISM of local spiral galaxies is far from homogeneous, with regions of size ∼1 kpc showing significant departures from the mean metallicity at each galactocentric radius.

scholarly journals The Integral Field View of the Orion Nebula

2014 ◽  
Vol 2014 ◽  
pp. 1-14
Author(s):  
Adal Mesa-Delgado
Keyword(s):  
Large Scale ◽  
3D Structure ◽  
Active Role ◽  
Small Scale ◽  
H Ii Regions ◽  
Orion Nebula ◽  
Star Forming ◽  
Star Forming Regions ◽  
Integral Field Spectroscopy ◽  
Integral Field

This paper reviews the major advances achieved in the Orion Nebula through the use of integral field spectroscopy (IFS). Since the early work of Vasconcelos and collaborators in 2005, this technique has facilitated the investigation of global properties of the nebula and its morphology, providing new clues to better constrain its 3D structure. IFS has led to the discovery of shock-heated zones at the leading working surfaces of prominent Herbig-Haro objects as well as the first attempt to determine the chemical composition of Orion protoplanetary disks, also known asproplyds. The analysis of these morphologies using IFS has given us new insights into the abundance discrepancy problem, a long-standing and unresolved issue that casts doubt on the reliability of current methods used for the determination of metallicities in the universe from the analysis of H II regions. Results imply that high-density clumps and high-velocity flows may play an active role in the production of such discrepancies. Future investigations based on the large-scale IFS mosaic of Orion will be very valuable for exploring how the integrated effect of small-scale structures may have impact at larger scales in the framework of star-forming regions.

scholarly journals Comparison of the Nutrient Content of Eggs from Commercial and Village Chickens in Rural Malawi (P03-009-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Rochelle Werner ◽  
Bess Caswell ◽  
Kenneth Maleta ◽  
Christine Stewart
Keyword(s):  
Vitamin D3 ◽  
Large Scale ◽  
Nutrient Content ◽  
The United States ◽  
Water Soluble ◽  
Small Scale ◽  
Convenience Sample ◽  
Nutrient Analysis ◽  
The Mean ◽  
The Village

Abstract Objectives To characterize the nutritional composition of chicken eggs from a large-scale commercial producer and a small-scale household producer in rural Malawi. Methods A convenience sample of 28 large commercial and 32 village eggs from Malawi were hardboiled and measured for the weight in grams of the whole egg, peeled egg, egg white, and egg yolk. A separate convenience sample of 11 commercial and 17 village eggs were selected for nutrient analysis. Eggs were hardboiled for 4 minutes, refrigerated, and shipped to a nutrient analysis lab in the United States. Eggs from each source were pooled and analyzed for macronutrients, amino acids, fatty acids, vitamins, and minerals. Analytes were reported per 100 g sample and converted to nutrients per egg using the mean peeled egg weight. Results The mean weight in grams of whole commercial eggs (59.4 ± 5.3) was 19 g greater than whole village eggs (40.4 ± 3.0). Commercial eggs had a 15 g greater mass of egg whites (37.0 ± 4.2) than village eggs (21.8 ± 2.5), but the mass of egg yolks only differed by one gram (commercial: 15.3 ± 1.0 and village: 14.1 ± 1.4). Per 100 g sample, commercial and village eggs had similar calories (143 kcals vs. 162kcals), protein (12.5 g vs. 12.5 g), water-soluble vitamins (1.61 µg vs. 1.92 µg Vitamin B-12; 63.5 µg vs. 59.9 µg folate, DFE) and minerals (1.7 mg vs. 2.1 mg iron; 21 µg vs. 24 µg selenium; 1.1 mg vs. 1.4 mg zinc). For fat-soluble nutrients, the 100 g sample of commercial eggs had a higher concentration of Vitamin A than the village eggs (150 µg vs. 102 µg RAE) but lower concentrations of Vitamin D3, α-tocopherol, and choline than the village eggs (0.8 µg vs. 2.9 µg Vitamin D3; 2.25 mg vs. 4.08 mg α-tocopherol; and 238 mg vs. 314 mg choline). However, when compared on a per egg basis, the fat-soluble nutrient content of the whole eggs was similar due to the smaller size of the village eggs. Conclusions On a per egg basis, eggs from small-scale households may deliver comparable amounts of fat-soluble nutrients but fewer calories, protein, and minerals compared to eggs from commercial producers; however, on a per 100 g basis, village eggs were a more nutrient-dense option. Funding Sources The Bill and Melinda Gates Foundation, BLUM Center of UC Davis.

Salinity Variations in the Southern California Current*

2005 ◽  
Vol 35 (8) ◽  
pp. 1421-1436 ◽  
Author(s):  
Niklas Schneider ◽  
Emanuele Di Lorenzo ◽  
Pearn P. Niiler
Keyword(s):  
Large Scale ◽  
Southern California ◽  
Current System ◽  
California Current ◽  
Southern California Bight ◽  
Small Scale ◽  
Climate Indices ◽  
California Current System ◽  
The Mean ◽  
Salinity Variations

Abstract Hydrographic observations southwestward of the Southern California Bight in the period 1937–99 show that temperature and salinity variations have very different interannual variability. Temperature varies within and above the thermocline and is correlated with climate indices of El Niño, the Pacific decadal oscillation, and local upwelling. Salinity variability is largest in the surface layers of the offshore salinity minimum and is characterized by decadal-time-scale changes. The salinity anomalies are independent of temperature, of heave of the pycnocline, and of the climate indices. Calculations demonstrate that long-shore anomalous geostrophic advection of the mean salinity gradient accumulates along the mean southward trajectory along the California Current and produces the observed salinity variations. The flow anomalies for this advective process are independent of large-scale climate indices. It is hypothesized that low-frequency variability of the California Current system results from unresolved, small-scale atmospheric forcing or from the ocean mesoscale upstream of the Southern California Bight.

Generation mechanism of a hierarchy of vortices in a turbulent boundary layer

2019 ◽  
Vol 865 ◽  
pp. 1085-1109 ◽  
Author(s):  
Yutaro Motoori ◽  
Susumu Goto
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Energy Spectrum ◽  
Turbulent Boundary Layer ◽  
Large Scale ◽  
Generation Mechanism ◽  
Small Scale ◽  
Generation Process ◽  
Mean Flow ◽  
The Mean

To understand the generation mechanism of a hierarchy of multiscale vortices in a high-Reynolds-number turbulent boundary layer, we conduct direct numerical simulations and educe the hierarchy of vortices by applying a coarse-graining method to the simulated turbulent velocity field. When the Reynolds number is high enough for the premultiplied energy spectrum of the streamwise velocity component to show the second peak and for the energy spectrum to obey the$-5/3$power law, small-scale vortices, that is, vortices sufficiently smaller than the height from the wall, in the log layer are generated predominantly by the stretching in strain-rate fields at larger scales rather than by the mean-flow stretching. In such a case, the twice-larger scale contributes most to the stretching of smaller-scale vortices. This generation mechanism of small-scale vortices is similar to the one observed in fully developed turbulence in a periodic cube and consistent with the picture of the energy cascade. On the other hand, large-scale vortices, that is, vortices as large as the height, are stretched and amplified directly by the mean flow. We show quantitative evidence of these scale-dependent generation mechanisms of vortices on the basis of numerical analyses of the scale-dependent enstrophy production rate. We also demonstrate concrete examples of the generation process of the hierarchy of multiscale vortices.

Relative Efficiency of Ancillary and Small Scale Units

1978 ◽  
Vol 3 (4) ◽  
pp. 279-284
Author(s):  
K.R. Shaligram
Keyword(s):  
Small Firms ◽  
Large Scale ◽  
Small Scale ◽  
Underlying Assumption ◽  
Significant Difference ◽  
End Products ◽  
Policy Measures ◽  
The Mean ◽  
Small Manufacturers ◽  
Better Than

Ancillary units are small firms manufacturing and supplying intermediate goods, typically to large firms. Several policy measures are under consideration to raise the output of the ancillary industry to the level of 15 per cent of the value of output of the large scale industry by 1985. The underlying assumption appears to be that the ancillary status enhances the prospect for the viability of the small firm. This paper examines whether ancillary units perform better than small scale units (small manufacturers of end products) under the conditions prevailing in India. The findings reveal no significant difference in the mean performance of the two classes of small firms. It also draws implications for policymakers and management from the findings.

The Effects of Scaling and Model Complexity in Simulating the Transport of Inorganic Micropollutants in a Lowland River Reach

2006 ◽  
Vol 41 (1) ◽  
pp. 24-36 ◽  
Author(s):  
Karl-Erich Lindenschmidt ◽  
René Wodrich ◽  
Cornelia Hesse
Keyword(s):  
Large Scale ◽  
Transport Model ◽  
Transport Processes ◽  
Model Complexity ◽  
Scale Model ◽  
Small Scale ◽  
Quality Model ◽  
Large Scale Model ◽  
Iron And Zinc ◽  
Physical And Chemical

Abstract A hypothesis stating that more complex descriptions of processes in models simulate reality better (less error) but with more unreliable predictability (more sensitivity) is tested using a river water quality model. This hypothesis was extended stating that applying the model on a domain of smaller scale requires greater complexity to capture the same accuracy as in large-scale model applications which, however, leads to increased model sensitivity. The sediment and pollutant transport model TOXI, a module in the WASP5 package, was applied to two case studies of different scale: a 90-km course of the 5th order (sensu Strahler 1952) lower Saale river, Germany (large scale), and the lock-and-weir system at Calbe (small scale) situated on the same river course. A sensitivity analysis of several parameters relating to the physical and chemical transport processes of suspended solids, chloride, arsenic, iron and zinc shows that the coefficient, which partitions the total heavy metal mass into its dissolved and sorbed fraction, is a very sensitive parameter. Hence, the complexity of the sorptive process was varied to test the hypotheses.

Field-aligned current ordering in ground and space measurements

2020 ◽  
Author(s):  
Malcolm Dunlop ◽  
Junying Yang ◽  
Xiangcheng Dong ◽  
Mervyn Freeman ◽  
Neil Rogers ◽  
...  
Keyword(s):  
Large Scale ◽  
Correlation Coefficients ◽  
Lower Latitude ◽  
Time Shift ◽  
Small Scale ◽  
Maximum Correlation ◽  
Substorm Activity ◽  
The Mean ◽  
Field Aligned Current ◽  
Statistical Trends

<p>The orientation of field-aligned current sheets (FACs) can be inferred from dual-spacecraft correlations of the FAC signatures between two Swarm spacecraft (A and C), using the maximum correlations obtained from sliding data segments. Statistical analysis of both the correlations and the inferred orientations shows clear trends in magnetic local time (MLT) which reveal behaviour of both large and small scale currents. The maximum correlation coefficients show distinct behaviour in terms of either the time shift, or the shift in longitude between Swarm A and C for various filtering levels. The lower-latitude FACs show the strongest correlations for a broad range of MLT centred on dawn and dusk, with a higher correlation coefficient on the dusk-side and lower correlations near noon and midnight, and broadly follow the mean shape of the auroral boundary for the lower latitudes corresponding to Region 2 FACs (and are most well-ordered on the dusk side). Individual events sampled by higher altitude spacecraft (e.g. the 4 Cluster spacecraft), in conjunction with Swarm (mapping both to region 1 and 2), also show two different domains of FACs: time variable, small-scale (10s km), and more stationary large-scale (>100 km) FACs. We investigate further how these FAC regimes are dependent on geomagnetic activity, focusing on high activity events. Both the statistical trends, and individual conjugate events, show comparable effects seen in the ground magnetometer signals (dH/dt) during storm/substorm activity and show distributions that are similar.</p>

The Use of Large Scale Parameters in Small Scale Diffusion Studies

1957 ◽  
Vol 38 (1.1) ◽  
pp. 6-12 ◽  
Author(s):  
William G. Tank
Keyword(s):  
Large Scale ◽  
Meteorological Parameters ◽  
Surface Wind ◽  
Small Scale ◽  
Relative Importance ◽  
Wind Vector ◽  
Scale Parameters ◽  
Diffusion Studies ◽  
The Mean ◽  
Low Levels

A method is set forth whereby gaseous diffusion in the low levels of the atmosphere can be calculated by Roberts' diffusion equation (modified to consider instantaneous volume sources) using only large scale synoptic parameters that are readily obtainable from the surface analysis and pibal reports. The three pertinent meteorological parameters utilized are: (1) the mean surface wind, (2) the angle between the surface wind vector and the surface isobars, and (3) the height of the gradient level. Theoretical and observed dosage values are compared by means of dosage isopleth diagrams. Results show that the method yields quite satisfactory results, with regard to both dosage magnitude and distribution. The assumptions necessary for the application of the method and its limitations are mentioned and their relative importance discussed.

Analysis of Synergies among the Ecological Factors of Farmland in a Township

2014 ◽  
Vol 556-562 ◽  
pp. 916-920
Author(s):  
Yu Huan Li ◽  
Deng Qiu Li ◽  
Jie Wu
Keyword(s):  
Large Scale ◽  
Ecological Factors ◽  
Mean Value ◽  
Small Scale ◽  
Medium Scale ◽  
Factorial Kriging ◽  
Spherical Models ◽  
Scale Range ◽  
The Mean ◽  
High Coordination

The spatial variability of single ecological factors of the farmland and the synergies among the ecological factors were studied by using geostatistical analysis and factorial kriging analysis (FKA).The results show that all of the spherical models of the co-variogram can be grouped into four parts: the nugget part, the small-scale part, the medium-scale part, and the large-scale part. The mean value of the small-scale range (1.12-1.85 km) is approximately 1.50 km, that of the medium-scale range (3.40-4.10 km) is approximately 3.8 km, and that of the large-scale range (9.35-10.10 km) is approximately 9.8 km. The correlations between each factor on the four scales vary, and the correlation between each factor on the medium scale is the strongest. In this paper, the ecological factors of the farmland on the medium scale have relatively consistent variability and sources, indicating that all of the factors on that scale have a high coordination.

scholarly journals Tracers and traceability: implementing the cirrus parameterisation from LACM in the TOMCAT/SLIMCAT chemistry transport model as an example of the application of quality assurance to legacy models

2009 ◽  
Vol 2 (2) ◽  
pp. 1299-1333
Author(s):  
A. M. Horseman ◽  
A. R. MacKenzie ◽  
M. P. Chipperfield
Keyword(s):  
Quality Assurance ◽  
Software Engineering ◽  
Large Scale ◽  
Best Practice ◽  
Transport Model ◽  
Acceptance Testing ◽  
Small Scale ◽  
Analysis Tool ◽  
Chemistry Transport Model ◽  
Research Software

Abstract. A new modelling tool for the investigation of large-scale behaviour of cirrus clouds has been developed. This combines two existing models, the TOMCAT/SLIMCAT chemistry transport model (nupdate library version 0.80, script mpc346_l) and cirrus parameterisation of Ren and MacKenzie (LACM implementation not versioned). The development process employed a subset of best-practice software engineering and quality assurance processes, selected to be viable for small-scale projects whilst maintaining the same traceability objectives. The application of the software engineering and quality control processes during the development has been shown to be not a great overhead, and their use has been of benefit to the developers as well as the end users of the results. We provide a step-by-step guide to the implementation of traceability tailored to the production of geo-scientific research software, as distinct from commercial and operational software. Our recommendations include: maintaining a living "requirements list"; explicit consideration of unit, integration and acceptance testing; and automated revision/configuration control, including control of analysis tool scripts and programs. Initial testing of the resulting model against satellite and in-situ measurements has been promising. The model produces representative results for both spatial distribution of the frequency of occurrence of cirrus ice, and the drying of air as it moves across the tropical tropopause. The model is now ready for more rigorous quantitative testing, but will require the addition of a vertical wind velocity downscaling scheme to better represent extra-tropical continental cirrus.

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