Search results for "ground"
showing 10 items of 2432 documents
Moisture source in the Hyblean mountains region (south-eastern Sicily,Italy):Evidence from stable isotopes signature
2006
Abstract Here the authors present results of an isotope study on precipitation collected during a 2-a period from a rain-gauge network consisting of 6 stations located at different elevations in the Hyblean Mountains (HM) region, in south-eastern Sicily. The slope of the local meteoric water line ( δD = 6.50 δ 18 O + 9.87) obtained for the region suggests that precipitation is affected by evaporation during rainfall events. The main variations in rainwater isotope composition are due to seasonal effects and elevation. An average 2 H excess value of +21.2‰ was found for precipitation events less affected by evaporation (i.e. when the rainfall was >65 mm/month). The spatial distribution of O…
Experimental and Theoretical Electron Density Determination for Two Norbornene Derivatives: Topological Analysis Provides Insights on Reactivity
2016
The electron density distribution of two substituted norbornene derivatives (cis-5-norbornene-endo-2,3-dicarboxylic anhydride (1) and 7-oxabicylo[2.2.1]hept-5-ene-exo-2,3-dicarboxylic anhydride (2) has been determined from low-temperature (20 K) X-ray diffraction data and from DFT calculations with periodic boundary conditions. Topological analysis of the electron density is discussed with respect to exo-selective additions, the partial retro-Diels-Alder (rDA) character of the ground state, and intermolecular interaction energies.
A PTFE membrane for the in situ extraction of dissolved gases in natural waters: Theory and applications
2005
[1] A new method for extracting dissolved gases in natural waters has been developed and tested, both in the laboratory and in the field. The sampling device consists of a polytetrafluroethylene (PTFE) tube (waterproof and gas permeable) sealed at one end and connected to a glass sample holder at the other end. The device is pre-evacuated and subsequently dipped in water, where the dissolved gases permeate through the PTFE tube until the pressure inside the system reaches equilibrium. A theoretical model describing the time variation in partial gas pressure inside a sampling device has been elaborated, combining the mass balance and “Solution-Diffusion Model” (which describes the gas permea…
Slinky inflation
2005
We present a new approach to quintessential inflation, in which both dark energy and inflation are explained by the evolution of a single scalar field. We start from a simple scalar potential with both oscillatory and exponential behavior. We employ the conventional reheating mechanism of new inflation, in which the scalar decays to light fermions with a decay width that is proportional to the scalar mass. Because our scalar mass is proportional to the Hubble rate, this gives adequate reheating at early times while shutting off at late times to preserve quintessence and satisfy nucleosynthesis constraints. We discuss a simple model which solves the horizon, flatness, and "why now" problems.…
Impact of general reionization scenarios on extraction of inflationary parameters
2010
Determination of whether the Harrison-Zel'dovich spectrum for primordial scalar perturbations is consistent with observations is sensitive to assumptions about the reionization scenario. In light of this result, we revisit constraints on inflationary models using more general reionization scenarios. While the bounds on the tensor-to-scalar ratio are largely unmodified, when different reionization schemes are addressed, hybrid models are back into the inflationary game. In the general reionization picture, we reconstruct both the shape and amplitude of the inflaton potential. We discuss how relaxing the simple reionization restriction affects the reconstruction of the potential through the c…
Primordial power spectrum features in phenomenological descriptions of inflation
2016
We extend an alternative, phenomenological approach to inflation by means of an equation of state and a sound speed, both of them functions of the number of $e$-folds and four phenomenological parameters. This approach captures a number of possible inflationary models, including those with non-canonical kinetic terms or scale-dependent non-gaussianities. We perform Markov Chain Monte Carlo analyses using the latest cosmological publicly available measurements, which include Cosmic Microwave Background (CMB) data from the Planck satellite. Within this parametrization, we discard scale invariance with a significance of about $10\sigma$, and the running of the spectral index is constrained as …
Augmenting the algorithm: emerging human-in-the-loop work configurations
2020
Abstract How do configurations of humans and algorithms evolve as firms adopt artificial intelligence (AI) capabilities, and what are the implications for work and organization? We explored these questions through a two-year long case study of an organization in the international maritime trade that introduced automated algorithmic support for data analysis and prediction work. Drawing on a human–machine configuration perspective, we found that humans and the algorithm were configured and reconfigured in multiple ways over time as the organization dealt with the introduction of algorithmic analysis. In contrast to replacing human work, the emergent configurations required new roles and redi…
Information Influence in Society’s Information Environment : An Empirical Analysis Using the Grounded Theory
2020
This paper investigates information influence in society’s Information Environment. The Grounded Theory approach was used to collect and to analyse the data. A conceptual framework of the thematic categories and item categories was developed on the basis of empirical evidence and past studies that reflect the findings of the field. The most fundamental components in this conceptual framework were six thematic categories (information influence, information operations, cyber operations, psychological operations, kinetic operations, and deception), their item categories, the items themselves, and the interrelationships between the thematic categories. The propositions regarding the thematic ca…
Grounded theory for generating theory in the study of behavior
2012
The use of grounded theory procedures for the study of information behavior has contributed to generating theory in this field. Thirty-one works were analyzed with regard to a) their relationship to the context in which the research was carried out, b) the aspect of information behavior researched, c) the use of grounded theory procedures, and d) the generation of theory. Most of the studies were carried out in the context of health information, and grounded theory procedures were for the most part only partially applied. The theoretical propositions produced depended on the subject being studied. Although this methodology is suitable for the study of an individual's interaction with inform…
Microwave, High-Resolution Infrared, and Quantum Chemical Investigations of CHBrF2: Ground and v4 = 1 States
2011
A combined microwave, infrared, and computational investigation of CHBrF(2) is reported. For the vibrational ground state, measurements in the millimeter- and sub-millimeter-wave regions for CH(79)BrF(2) and CH(81)BrF(2) provided rotational and centrifugal-distortion constants up to the sextic terms as well as the hyperfine parameters (quadrupole-coupling and spin-rotation interaction constants) of the bromine nucleus. The determination of the latter was made possible by recording of spectra at sub-Doppler resolution, achieved by means of the Lamb-dip technique, and supporting the spectra analysis by high-level quantum chemical calculations at the coupled-cluster level. In this context, the…