Assessing the extraction efficiency of CaCl2 and rhizon extraction methods after the application of organic matter and CaCl2 as soil amendments to enhance the mobility of Cd and Zn

A pot experiment was conducted to study the extractability of cadmium and zinc by CaCl 2 and rhizon extraction methods after the application of organic matter and chloride as soil amendments. Two methods, Rhizon and CaCl 2 extraction methods were concurrently employed to study the effects of the various amendments on the mobility of Cd and Zn. Both CaCl 2 and Rhizon extraction methods generally extracted appreciable amounts of the heavy metals after the application of the amendments. However, the results from the experiment shows that the Rhizon samplers extracted higher concentrations of both Cd and Zn as compared to the CaCl 2 extraction method. The use of rhizon soil moisture sampler is also non destructive to the soil and makes it possible to ascertain levels of heavy metals at equilibrium in the soil solution without changing the compisition of the soil solution in the process of extracting it. Assessment of the soil pH in the soil samples and the Rhizon extracts after the application of the amendments showed no significant difference with the control. Comparatively, application of CaCl 2 had a significant mobilizing effect on the mobility of both Cd and Zn as a result of the combined effect of complexation of Cd and Zn by the chloride anion, and by the fact that Cd and Zn are referentially absorbed in cation exchange positions. Therefore the Ca 2+ ion can displace these metals into the soil solution

Wrapped feature selection for neural networks in direct marketing.

In this paper, we try to validate existing theory on and develop additional insight into repeat purchasing behaviour in a direct-marketing setting by means of an illuminating case study. The case involves the detection and qualification of the most relevant RFM (Recency, Frequency and Monetary) features, using a wrapped feature selection method in a neural network context. Results indicate that elimination of redundant/irrelevant features by means of the discussed feature selection method, allows to significantly reduce model complexity without degrading generalisation ability. It is precisely this issue that will allow to infer some very interesting marketing conclusions concerning the relative importance of the RFM-predictor categories. The empirical findings highlight the importance of a combined use of all three RFM variables in predicting repeat purchase behaviour. However, the study also reveals the dominant role of the frequency variable. Results indicate that a model including only frequency variables still yields satisfactory classification accuracy compared to the optimally reduced model.Marketing; Networks; Selection; Theory; Purchasing; Case studies; Studies; Model; Variables; Yield; Classification; Neural networks;

Bayesian neural network learning for repeat purchase modelling in direct marketing.

We focus on purchase incidence modelling for a European direct mail company. Response models based on statistical and neural network techniques are contrasted. The evidence framework of MacKay is used as an example implementation of Bayesian neural network learning, a method that is fairly robust with respect to problems typically encountered when implementing neural networks. The automatic relevance determination (ARD) method, an integrated feature of this framework, allows to assess the relative importance of the inputs. The basic response models use operationalisations of the traditionally discussed Recency, Frequency and Monetary (RFM) predictor categories. In a second experiment, the RFM response framework is enriched by the inclusion of other (non-RFM) customer profiling predictors. We contribute to the literature by providing experimental evidence that: (1) Bayesian neural networks offer a viable alternative for purchase incidence modelling; (2) a combined use of all three RFM predictor categories is advocated by the ARD method; (3) the inclusion of non-RFM variables allows to significantly augment the predictive power of the constructed RFM classifiers; (4) this rise is mainly attributed to the inclusion of customer\slash company interaction variables and a variable measuring whether a customer uses the credit facilities of the direct mailing company.Marketing; Companies; Models; Model; Problems; Neural networks; Networks; Variables; Credit;

The cosmic-ray air-shower signal in Askaryan radio detectors

We discuss the radio emission from high-energy cosmic-ray induced air showers hitting Earth's surface before the cascade has died out in the atmosphere. The induced emission gives rise to a radio signal which should be detectable in the currently operating Askaryan radio detectors built to search for the GZK neutrino flux in ice. The in-air emission, the in-ice emission, as well as a new component, the coherent transition radiation when the particle bunch crosses the air-ice boundary, are included in the calculations

Optical Spectroscopy of Distant Red Galaxies

We present optical spectroscopic follow-up of a sample of Distant Red Galaxies (DRGs) with K 2.3, in the Hubble Deep Field South, the MS 1054-03 field, and the Chandra Deep Field South. Spectroscopic redshifts were obtained for 15 DRGs. Only 2 out of 15 DRGs are located at z < 2, suggesting a high efficiency to select high-redshift sources. From other spectroscopic surveys in the CDFS targeting intermediate to high redshift populations selected with different criteria, we find spectroscopic redshifts for a further 30 DRGs. We use the sample of spectroscopically confirmed DRGs to establish the high quality (scatter in \Delta z/(1+z) of ~ 0.05) of their photometric redshifts in the considered deep fields, as derived with EAZY (Brammer et al. 2008). Combining the spectroscopic and photometric redshifts, we find that 74% of DRGs with K 2. The combined spectroscopic and photometric sample is used to analyze the distinct intrinsic and observed properties of DRGs at z 2. In our photometric sample to K < 22.5, low-redshift DRGs are brighter in K than high-redshift DRGs by 0.7 mag, and more extincted by 1.2 mag in Av. Our analysis shows that the DRG criterion selects galaxies with different properties at different redshifts. Such biases can be largely avoided by selecting galaxies based on their rest-frame properties, which requires very good multi-band photometry and high quality photometric redshifts.Comment: Accepted for publication in the Astrophysical Journal, 13 pages, 8 figures, 5 table

The influence of orbital rotation on the energy of closed-shell wavefunctions

The orbital dependence of closed-shell wavefunction energies is investigated by performing doubly-occupied configuration interaction (DOCI) calculations, representing the most general class of these wavefunctions. Different local minima are examined for planar hydrogen clusters containing two, four, and six electrons applying (spin) symmetry-broken restricted, unrestricted, and generalised orbitals with real and complex coefficients. Contrary to Hartree-Fock (HF), restricted DOCI is found to properly break bonds and thus unrestricted orbitals, while providing a quantitative improvement of the energy, are not needed to enforce a qualitatively correct bond dissociation. For the beryllium atom and the BH diatomic, the lowest possible HF energy requests symmetry-broken generalised orbitals, whereas accurate results for DOCI can be obtained within a restricted formalism. Complex orbital coefficients are shown to increase the accuracy of HF and DOCI results in certain cases. The computationally inexpensive AP1roG geminal wavefunction is proven to agree very well with all DOCI results of this study

Interpretation of the cosmic-ray air shower signal in Askaryan radio detectors

We discuss the radio emission from a cosmic-ray air shower propagating in air before it hits an air-ice boundary after which it completes its propagation inside the ice. The in-air emission, the in-ice emission, as well as the transition radiation from the shower crossing the boundary is considered. We discuss the interpretation of the radio signal observed by an in-ice observer