How Much Do Teachers Earn?

In the continuing debate over how to improve education systems, many people argue that teachers` salaries need to be increased. This paper seeks to establish a reliable method for analyzing the issue using household survey data from Bolivia.

Influence of extraction methods on the composition of essential oils of Achillea millefolium L. from Lithuania

In this study, flowering aerial parts of Achillea millefolium were used as a matrix for supercritical CO2 extraction (SFE) of volatile oil. The collected extracts were analyzed by GC-FID and GC-MS methods and their composition were compared with that of the essential oil isolated by hydrodistillation (HD). The composition of the essential oil obtained by hydrodistillation and SFE methods is widely different. Indeed, the SFE volatile oil had a pale yellow color whereas the HD oil had a blue color due to the presence of chamazulene (48.0% vs. 4.3%). Other important constituents of HD oil were (E)- caryophyllene (19.5 %) and γ-muurolene (13.1%). The CO2 supercritical extract was dominated by (E)-caryophyllene (26.0%), γ-muurolene (22.0%), and caryophyllene oxide (8.1%)

Cerebellar structural variations in subjects with different hypnotizability

Hypnotizability-the proneness to accept suggestions and behave accordingly-has a number of physiological and behavioral correlates (postural, visuomotor, and pain control) which suggest a possible involvement of cerebellar function and/or structure. The present study was aimed at investigating the association between cerebellar macro- or micro-structural variations (analyzed through a voxel-based morphometry and a diffusion tensor imaging approach) and hypnotic susceptibility. We also estimated morphometric variations of cerebral gray matter structures, to support current evidence of hypnotizability-related differences in some cerebral areas. High (highs, N = 12), and low (lows, N = 37) hypnotizable healthy participants (according to the Stanford Hypnotic Susceptibility Scale, form A) were submitted to a high field (3 T) magnetic resonance imaging protocol. In comparison to lows, highs showed smaller gray matter volumes in left cerebellar lobules IV/V and VI at uncorrected level, with the results in left lobule IV/V maintained also at corrected level. Highs showed also gray matter volumes smaller than lows in right inferior temporal gyrus, middle and superior orbitofrontal cortex, parahippocampal gyrus, and supramarginal parietal gyrus, as well as in left gyrus rectus, insula, and middle temporal cortex at uncorrected level. Results of right inferior temporal gyrus survived also at corrected level. Analyses on micro-structural data failed to reveal any significant association. The here found morphological variations allow to extend the traditional cortico-centric view of hypnotizability to the cerebellar regions, suggesting that cerebellar peculiarities may sustain hypnotizability-related differences in sensorimotor integration and emotional contro

Correlated electron-hole plasma in organometal perovskites

Organic-inorganic perovskites are a class of solution-processed semiconductors holding promise for the realization of low-cost efficient solar cells and on-chip lasers. Despite the recent attention they have attracted, fundamental aspects of the photophysics underlying device operation still remain elusive. Here we use photoluminescence and transmission spectroscopy to show that photoexcitations give rise to a conducting plasma of unbound but Coulomb-correlated electron-hole pairs at all excitations of interest for light-energy conversion and stimulated optical amplification. The conductive nature of the photoexcited plasma has crucial consequences for perovskite-based devices: in solar cells, it ensures efficient charge separation and ambipolar transport while, concerning lasing, it provides a low threshold for light amplification and justifies a favourable outlook for the demonstration of an electrically driven laser. We find a significant trap density, whose cross-section for carrier capture is however low, yielding a minor impact on device performance

Surface reactivity of tributyl thiophosphate: effects of temperature and mechanical stress

The surface reactivity of tributyl thiophosphate on iron surfaces has been studied in situ by attenuated total reflection Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and temperature-programmed reaction and desorption spectroscopies. The results show that at temperatures lower than 373K the molecule forms a physisorbed layer on the iron substrate. At 373K a reaction takes place with the formation of an organic layer, together with iron polyphosphate and sulfate. At higher temperatures temperature-programmed desorption results suggest that the mechanism involves P-O bond scission to yield butoxy groups. This could be preceded by P=S bond scission to give tributyl phosphite, which then, in turn, undergoes P-O bond scission to produce butoxy groups. The results obtained following tribological testing are in agreement with those of thermal tests: evidence of polyphosphate and sulfate formation is foun

Multimodal-based Diversified Summarization in Social Image Retrieval

In this paper, we describe our approach and its results for the MediaEval 2015 Retrieving Diverse Social Images task. The main strength of the proposed approach is its flexibility that permits to filter out irrelevant images, and to obtain a reli- able set of diverse and relevant images. This is done by first clustering similar images according to their textual descrip- tions and their visual content, and then extracting images from different clusters according to a measure of user’s cred- ibility. Experimental results shown that it is stable and has little fluctuation in both single-concept and multi-concept queries

Appearance of breast cysts in planar geometry photoacoustic mammography using 1064-nm excitation

In the search for improved imaging modalities for detection and diagnosis of breast cancer, a high negative prediction value is also important. Photoacoustic (optoacoustic) imaging is a relatively new technique that has high potential for visualizing breast malignancies, but little is known about the photoacoustic appearance of benign lesions. In this work, we investigate the visibility of benign breast cysts in forward-mode photoacoustic mammography using 1064-nm light, as currently applied in the Twente photoacoustic mammoscope. Results from (Monte Carlo and k-wave) simulations and phantom measurements were used to interpret results from patient measurements. There was a strong agreement among the results from simulations, phantom, and patient measurements. Depending on the absorption contrast between cyst and breast tissue, cysts were visible as either one or two confined high-contrast areas representing the front and the back of the cyst, respectively. This edge enhancement is most likely the consequence of the local sudden change in the absorbed energy density and Grüneisen coefficients. Although the current forward-mode single-wavelength photoacoustic mammoscope cannot always unambiguously discriminate cysts from malignancies, this study reveals specific features of cysts compared to malignancies, which can be exploited for discrimination of the two abnormalities in future modifications of the image

Optimized electro- and wet-spinning techniques for the production of polymeric fibrous scaffolds loaded with bisphosphonate and hydroxyapatite

This research activity was aimed at the development of composite bioactive scaffolds made of biodegradable three-arm branched-star poly(ε-caprolactone) (∗PCL), hydroxyapatite nanoparticles (HNPs) and clodronate (CD), a bisphosphonate that has demonstrated efficacy in the treatment of various bone diseases and as an anti-inflammatory drug. During the experimental work, the processing conditions for the fabrication of fibrous meshes, by either electrospinning or wetspinning, were optimized. Stemming from a previous research activity on electrospinning of ∗PCL, ∗PCL/HNPs 3D meshes were developed, evaluating the influence of fabrication parameters on the fibres’ morphology. By exploiting the binding affinity of bisphosphonates for hydroxyapatite, a methodology was set up for obtaining a physical linkage between CD and HNPs, with the aim of having a dual bioactive system loaded into ∗PCL fibrous mats. Fibres loaded with either CD or CD–HNP particles were thus produced and analysed by scanning electron microscopy for their morphology and by energy dispersive X-ray spectroscopy for their elemental compositionThis work was done within the framework of the European Network of Excellence 'EXPERTISSUES', Project No. NMP3-CT-2004-500283. Professor Ramani Narayan of Michigan Biotechnology Institute and Dr Fabio Neggiani of Abiogen Pharma-Pisa are acknowledged for supplying *PCL and CD, respectively