3,003 research outputs found
Accurate Modeling of Weak Lensing with the sGL Method
We revise and extend the stochastic approach to cumulative weak lensing
(hereafter the sGL method) first introduced in Ref. [1]. Here we include a
realistic halo mass function and density profiles to model the distribution of
mass between and within galaxies, galaxy groups and galaxy clusters. We also
introduce a modeling of the filamentary large-scale structures and a method to
embed halos into these structures. We show that the sGL method naturally
reproduces the weak lensing results for the Millennium Simulation. The strength
of the sGL method is that a numerical code based on it can compute the lensing
probability distribution function for a given inhomogeneous model universe in a
few seconds. This makes it a useful tool to study how lensing depends on
cosmological parameters and its impact on observations. The method can also be
used to simulate the effect of a wide array of systematic biases on the
observable PDF. As an example we show how simple selection effects may reduce
the variance of observed PDF, which could possibly mask opposite effects from
very large scale structures. We also show how a JDEM-like survey could
constrain the lensing PDF relative to a given cosmological model. The updated
turboGL code is available at turboGL.org.Comment: PRD style: 20 pages, 10 figures; replaced to match the improved
version accepted for publication in PRD. The updated turboGL code can be
downloaded at http://www.turbogl.org
Modeling seasonal branch carbon dynamics in pistachio as a function of crop load
A simplified model for the prediction of carbon balance was developed to elucidate the seasonal trend of sink-source relationships in bearing and non-bearing pistachio (Pistacia vera L.) branches. Seasonal changes in growth rate of vegetative (leaf and shoot) and reproductive (infructescence) organs were monitored in branches of mature rainfed pistachio trees during the entire growing season (AprilâSeptember). Simulations from the model were used to gain understanding of the implications of crop load on branch carbon (C) depletion and alternate bearing. Results showed that the pistachio branch was energetically able to sustain up to two infructescences (âŒ28 fruits) having a slightly positive carbon budget (2.6 g of C) at the end of the season. A branch with 4 infructescences (âŒ56 fruits) ended the season with a very negative carbon budget (-14.1 g of C) suggesting the implication of resource mobilization during heavy crop load. The simulations with the model allowed the identification of two energetically critical periods for pistachio, both characterized by a decreasing trend of the carbon budget. The first is at the beginning of the season, from leaf out until 35/40 days after full bloom (DAFB), when leaves are still not source of carbon, and the branch energetic need is largely satisfied by the remobilization of carbon from the reserves accumulated the previous year and stored through the winter. The second critical period is at the end of the season for bearing branches, at âŒ100 DAFB, when a strong reduction in leaf area due to early leaf senescence and drop coincides with high carbon request for kernel growth. Overall, results demonstrate that the branch carbon budget model is a valid tool to study bearing dynamics in tree species and can help to develop physiologically-based management strategies for achieving increased and more constant productions in pistachio orchard systems
High-resolution UAV imagery for field olive (Olea europaea L.) phenotyping
Remote sensing techniques based on images acquired from unmanned aerial vehicles (UAVs) could represent an effective tool to speed up the data acquisition process in phenotyping trials and, consequently, to reduce the time and cost of the field work. In this study, we assessed the ability of a UAV equipped with RGB-NIR cameras in highlighting differences in geometrical and spectral canopy characteristics between eight olive cultivars planted at different planting distances in a hedgerow olive orchard. The relationships between measured and estimated canopy height, projected canopy area and canopy volume were linear regardless of the different cultivars and planting distances (RMSE of 0.12 m, 0.44m2 and 0.68m3, respectively). Agood relationship (R2 = 0.95) was found between the pruning mass material weighted on the ground and its volume estimated by aerial images. NDVI measured in February 2019 was related to fruit yield per tree measured in November 2018, whereas no relationships were observed with the fruit yield measured in November 2019 due to abiotic and biotic stresses that occurred before harvest. These results confirm the reliability of UAV imagery and structure from motion techniques in estimating the olive geometrical canopy characteristics and suggest further potential applications of UAVs in early discrimination of yield efficiency between different cultivars and in estimating the pruning material volume
Palaeomagnetic results from an archaeological site near Rome (Italy): new insights for tectonic rotation during the last 0.5 Myr
Approximately 20 km north-east of Rome, along the modern trace of the Tiburtina road, recent archaeological diggings have brought to light a system of aqueduct galleries constructed by Roman engineers. This site falls inside the Acque Albule Basin, a travertine plateau Upper Pleistocene in age, that has been interpreted as a rhombshaped pull-apart basin created by strike-slip faulting within a N-S shear zone. This study provides evidence that two narrow water channels of this aqueduct system were significantly deformed by tectonic movement that occurred subsequent to their construction (II-III century A.D.). The geometry of the deformation pattern is compatible with that expected for a shear zone bounded by N-S oriented, right-lateral faults. The palaeomagnetic study of the volcanic formation («Pozzolane Rosse» Formation, 457± 4 kyr) containing the Roman aqueduct system evidences significant clockwise rotation around sub-vertical axis, consistent with the above-mentioned tectonic style
The Atmospheric Dispersion Corrector Software for the VST
The effects of atmospheric differential refraction on astrophysical measurements are well known. In particular, as a ray of light passes through the atmosphere, its direction is altered by the effects of atmospheric refraction. The amount of this effect depends basically on the variation of the refractive index along the path of the ray. The real accuracy needed in the atmosphere model and in the calculation of the correction to be applied is of course, considerably worse, especially at large zenith angles. On the VLT Survey Telescope (VST) the use of an Atmospheric Dispersion Corrector (ADC) is foreseen at a wide zenith distance range. This paper describes the software design and implementation aspects regarding the analytical correction law discovered to correct the refraction effect during observations with VST
Assessment of Trends and Uncertainties in the Atmospheric Boundary Layer Height Estimated Using Radiosounding Observations over Europe
Trends in atmospheric boundary layer height may represent an indication of climate changes. The related modified interaction between the surface and free atmosphere affects both thermodynamics variables and dilution of chemical constituents. Boundary layer is also a major player in various feedback mechanisms of interest for climate models. This paper investigates trends in the nocturnal and convective boundary layer height at mid-latitudes in Europe using radiosounding profiles from the Integrated Global Radiosounding Archive (IGRA). Atmospheric data from the European Centre for Medium-Range Weather Forecasts (ECMWF) ReAnalysis v5 (ERA5) and from the GCOS Reference Upper-Air Network (GRUAN) Lindenberg station are used as intercomparison datasets for the study of structural and parametric uncertainties in the trend analysis. Trends are calculated after the removal of the lag-1 autocorrelation term for each time series. The study confirms the large differences reported in literature between the boundary layer height estimates obtained with the two different algorithms used for IGRA and ERA5 data: ERA5 shows a density distribution with median values of 350 m and 1150 m for the night and the daytime data, respectively, while the corresponding IGRA median values are of 1150 m and 1750 m. An overall good agreement between the estimated trends is found for nighttime data, while daytime ERA5 boundary layer height estimates over Europe are characterized by a lower spatial homogeneity than IGRA. Parametric uncertainties due to missing data in both the time and space domain are also investigated: the former is not exceeding 1.5 m, while the latter are within 10 m during night and 17 m during the day. Recommendations on dataset filtering based on time series completeness are provided. Finally, the comparison between the Lindenberg data as processed at high-resolution by GRUAN and as provided to IGRA at a lower resolution, shows the significant impact of using high-resolution data in the determination of the boundary layer height, with differences from about 200 m to 450 m for both night and day, as well as a large deviation in the estimated trend
Radiometric age constraints for glacial terminations IX and VII
Buried sedimentary aggradational sections deposited between 800 ka and 600 ka in the
Tiber River coastal alluvial plain have been studied using borecores from around Rome. 40Ar/39Ar
ages on sanidine and/or leucite from intercalated tephra layers and paleomagnetic investigation of
clay sections provide geochronological constraints on the timing of aggradation of two of these
alluvial sections, and demonstrate that they were deposited in response to eustatic sea level rise
caused by glacial terminations IX and VII. 40Ar/39Ar age data indicate ages of 802 ± 8 ka and 649
± 3 ka for glacial terminations IX, and VII, respectively, providing a rare test, beyond the range
of U-series dating for corals and speleothems (~500 ka), of the astronomically calibrated
timescale developed for oxygen isotope records from deep sea cores
Avaliação do crescimento vegetativo em cafeeiro arĂĄbica e sua dependĂȘncia com fatores climĂĄticos no Estado de GoiĂĄs.
Objetivou-se avaliar o crescimento vegetativo em Coffea arabica e relacionĂĄ-lo com os fatores climĂĄticos, tendo como base o crescimento sazonal dos ramos ortotrĂłpicos e plagiotrĂłpicos, com diferentes idades, em condiçÔes irrigadas e nĂŁo irrigadas, sujeitos as alteraçÔes climĂĄticas e ao dĂ©ficit hĂdrico no Cerrado Goiano.Conpeex 2010
Real Estate Asset Management Companiesâ Economies of Scale: Is It a Dream or Reality? The Italian Case
The research focuses on a sample of 26 Italian real estate asset management companies (SocietĂ di Gestione del Risparmio âSGRâ)âwhose asset management is totally linked to real estate fundsâthat considers a period of six years (2013â2018). Using some variables extrapolated from the internal accountability of each SGR, the analysis investigates possible relationships between them to verify the presence or absence of economies of scale of Italian real estate management companies by multivariate regressions. The results show that there is no single model for profit maximization and cost minimization, but all depends on the business model that each SGR decides to adopt
Transcriptomic Analysis of the Pistacia vera (L.) Fruits Enable the Identification of Genes and Hormone-Related Gene Linked to Inflorescence Bud Abscission
Pistacia vera (L.) is an alternate bearing species. The tree produces axillary inflorescence buds every year. Still, they abscise in âONâ overloaded shoots, causing a limited production in the following âOFFâ year, causing a significant and unfavorable production fluctuation. In this work, we carried out de novo discovery and transcriptomic analysis in fruits of âONâ and âOFFâ shoots of the cultivar Bianca. We also investigated whether the fruit signaling pathway and hormone biosynthesis directly or indirectly linked to the premature fall of the inflorescence buds causing alternate bearing. We identified 1536 differentially expressed genes (DEGs) in fruits of âONâ vs. âOFFâ shoots, which are involved primarily in sugar metabolism, plant hormone pathways and transcription factors. The premature bud abscission linked to the phenomenon is attributable to a lack of nutrients (primarily sugar) and the possible competition between the same branchesâ sinks (fruits vs. inflorescence buds). Hormone pathways are involved as a response to signals degradation and remobilization of carbon and nutrients due to the strengthening of the developing embryos. Genes of the secondary metabolism and transcription factors are also involved in tailoring the individual branches response to the nutritional stress and sink competition. Crosstalk among sugar and various hormone-related genes, e.g., ethylene, auxin, ABA and cytokinin, were determined. The discovery of putative biomarkers like callose synthase 5, trehalose-6-phosphate synthase, NAD(P)-linked oxidoreductase and MIOX2, Jasmonate, and salicylic acid-related genes can help to design precision farming practices to mitigate the alternate bearing phenomenon to increase farming profitability. The aim of the analysis is to provide insight into the gene expression profiling of the fate of âONâ and âOFFâ fruits associated with the alternate bearing in the pistachio
- âŠ