Self-critical Rumination and Associated Metacognitions as Mediators of the Relationship Between Perfectionism and Self-esteem.

Past research has shown that perfectionism, can negatively impact self-esteem. However, the mediating factors that explain this relationship remain unclear. The current study aimed to investigate whether specific cognitive processes, namely, self-critical rumination and associated metacognitions, mediate this relationship. An opportunity sample of 347 participants completed a battery of online questionnaires measuring clinical perfectionism, self-critical rumination, metacognitions about self-critical rumination, self-esteem, and levels of psychological distress. Several hypotheses were tested to examine the associations between the study variables. Following this, a path analysis was used to determine whether the influence of perfectionistic concerns and perfectionistic striving on self-esteem is mediated by positive metacognitions about self-critical rumination, self-critical rumination, and negative metacognitions about self-critical rumination, serially. Positive metacognitions about self-critical rumination, self-critical rumination, and negative metacognitions about self-critical rumination partially mediated the relationship between perfectionistic concerns and self-esteem and fully mediated the relationship between perfectionistic striving and self-esteem. These results point towards possible interventions for those who struggle with low self-esteem due to their perfectionistic tendencies. Further investigations should explore additional factors that help to explain why perfectionism impacts self-esteem levels, whilst also addressing the limitations of this current research

Spectral sensitivity of the discoloration of Historical rag paper

This paper discusses the spectral sensitivity of the discoloration of historical rag paper simultaneously affected by Relative Humidity (RH) and Oxygen concentration [O2] in the ambient environment. Sacrificial samples were degraded using narrowband radiation sources centred at 450 nm, 525 nm, and 625 nm in combinations of RH and [O2] at two levels: 0% [O2] and 70% RH, 21% [O2] and 70% RH, 0% [O2] and 20% RH, and 21% [O2] and 20% RH. Diffuse reflectance was measured before and during the degradation experimental runs. Consistent qualitative results were obtained for the change in reflectance and the change in tristimulus total color change in CIELAB color space. In both cases, the increase of discoloration was modelled logarithmically over time. Among the three factors investigated in this research, wavelength of the radiation (Λ) was found to have the strongest effect. The radiation at 450 nm induced the most and fastest discoloration whereas the radiation at 625 nm induced the least and slowest discoloration. This spectral dependence was likely to be related to the photo energies at different wavelengths, but other factors were found to have played a role. Further analyses revealed that the main effects and the effects of the interactions between [O2] and Λ and between RH and Λ on the discoloration of historical rag paper were statistically significant. It suggests that managing the spectral power distribution of the radiation source can be crucial in the collection management

Quantitative NIR spectroscopy for determination of degree of polymerisation of historical paper

This paper discusses the development of a near infrared (NIR) spectroscopic method coupled with multivariate analysis to characterise historical paper. Specifically, partial least squares (PLS) regression was used to predict one of the most important properties of paper as a condition indicator – degree of polymerisation (DP). Supported by a set of model cellulose samples, the NIR-PLS method for DP prediction was validated and the modelling approach that led to the best prediction of DP of paper was established. The coefficient of variation of the NIR-PLS models were found to be approximately 8% and 20% of the DP of model cellulose and historical paper, respectively. The variance of the reference DP, the variance of the predicted DP, and the model bias were identified as the main sources of the total expected generalisation error of prediction. For both model cellulose and historical paper, the variance of the predicted DP by the NIR-PLS models contributed the most to the total error of prediction. This suggests that improving the instrumentation and the operation procedure is essential to improve model performance. Furthermore, the effect of water content of the samples on model performance was investigated. The model for historical paper was proven to be robust to relative humidity fluctuations between 30% and 70%, indicating the applicability of the model for collection surveys in a range of environments

Factorial experimentation on photodegradation of historical paper by polychromatic visible radiation

Quantification of the degradation behaviour of heritage objects is essential to manage the rate of degradation and hence optimise their lifetime. In this research, a 23 full factorial experiment was carried out to deepen the understanding of the photodegradation of historical rag paper induced by continuous polychromatic visible radiation. Oxygen concentration, relative humidity and illuminance were investigated as the three environmental factors of primary concern. The effects of these factors on the rate constant of change in diffuse reflectance and tristimulus discolouration were investigated by analysis of variance and multiple linear regression. The three main effects were found to contribute the most to the rate of photodegradation of historical paper, among which relative humidity played the most important role whereas illuminance played the least. This observation is likely to hold when extrapolating the experimental conditions to real conditions in collection storage and display

High field magneto-transport in high mobility gated InSb/InAlSb quantum well heterostructures

We present high field magneto-transport data from a range of 30nm wide InSb/InAlSb quantum wells. The low temperature carrier mobility of the samples studied ranged from 18.4 to 39.5 m2V-1s-1 with carrier densities between 1.5x1015 and 3.28x1015 m-2. Room temperature mobilities are reported in excess of 6 m2V-1s-1. It is found that the Landau level broadening decreases with carrier density and beating patterns are observed in the magnetoresistance with non-zero node amplitudes in samples with the narrowest broadening despite the presence of a large g-factor. The beating is attributed to Rashba splitting phenomenon and Rashba coupling parameters are extracted from the difference in spin populations for a range of samples and gate biases. The influence of Landau level broadening and spin-dependent scattering rates on the observation of beating in the Shubnikov-de Haas oscillations is investigated by simulations of the magnetoconductance. Data with non-zero beat node amplitudes are accompanied by asymmetric peaks in the Fourier transform, which are successfully reproduced by introducing a spin-dependent broadening in the simulations. It is found that the low-energy (majority) spin up state suffers more scattering than the high-energy (minority) spin down state and that the absence of beating patterns in the majority of (lower density) samples can be attributed to the same effect when the magnitude of the level broadening is large

Analytical robustness of quantitative NIR chemical imaging for Islamic paper characterization

Recently, spectral imaging techniques such as Multispectral (MSI) and Hyperspectral Imaging (HSI) have gained importance in the field of heritage conservation. This paper explores the analytical robustness of quantitative chemical imaging for Islamic paper characterization by focusing on the effect of different measurement and processing parameters, i.e. acquisition conditions and calibration on the accuracy of the collected spectral data. This will provide a better understanding of the technique that can provide a measure of change in collections through imaging. For the quantitative model, special calibration target was devised using 105 samples from a well-characterized reference Islamic paper collection. Two material properties were of interest: starch sizing and cellulose degree of polymerization (DP). Multivariate data analysis methods were used to develop discrimination and regression models which were used as an evaluation methodology for the metrology of quantitative NIR chemical imaging. Spectral data were collected using a pushbroom HSI scanner (Gilden Photonics Ltd) in the 1000-2500 nm range with a spectral resolution of 6.3 nm using a mirror scanning setup and halogen illumination. Data were acquired at different measurement conditions and acquisition parameters. Preliminary results showed the potential of the evaluation methodology to show that measurement parameters such as the use of different lenses and different scanning backgrounds may not have a great influence on the quantitative results. Moreover, the evaluation methodology allowed for the selection of the best pre-treatment method to be applied to the data. © (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Early stages of surface alteration of soda-rich-silicate glasses in the museum environment

This paper studied the alteration of three soda-rich-silicate glass types (Cristallo, façon-de-Venise and soda-lime silicate). Replica samples were exposed to different environments simulating museum-like conditions – room temperature and different relative humidities (RH). Results were analysed by SIMS, μ-FTIR, Optical Microscopy and Optical 3D profilometry. Cristallo appears as the most vulnerable, whilst the soda-lime glass appears as the most resistant to the environmental deterioration. The thickness of the altered layer is proportional to the time of exposure and to the RH of the surrounding atmosphere. From the results obtained, the glass composition and the water available and adsorbed to the surface strongly influence the kinetics of the surface alteration

Material properties of Islamic paper

In contrast to scientific research focussing on European paper, there is a significant gap in our knowledge of Islamic papermaking. This research surveys the evidence of techniques and materials typically used in Islamic papermaking, to deduce what might be considered as the most significant characteristics. A substantial collection of 228 Islamic papers (~18th–20th century) was characterized using chemical analytical methods: surface profilometry, gloss measurements, specular vs. diffuse reflectance ratio at 457 nm, scanning electron microscopy and infrared spectroscopy for identification of polishing, iodine test for identification of starch, Raspail test for identification of rosin, and fibre furnish analysis. Morphological analysis was performed to examine the presence of watermarks and sieve patterns. In addition, acidity and degree of polymerization of cellulose in paper were determined to explore the average material state of paper in the collection. Near infrared spectroscopic data of the collection were correlated to chemical properties with the aid of multivariate data analysis methods. Four different models were developed focusing on two main characteristics of Islamic paper: two for identification of polishing and starch, and two quantitative models to determine the acidity and degree of polymerization of cellulose in paper. While no single defining characteristic of Islamic paper was identified, 88 % of all papers in the studied collection either contain starch or are polished, or both. ~2 % of papers contain rosin. The majority of papers are neutral to mildly acidic, which is in contrast to their extensive degradation: ~69 % have DP < 1000. Polishing and starch appear to be associated with current values of pH and DP. The developed non-destructive characterization methodology could be applied to Islamic collections in libraries and archives to expand the database with the material properties of papers of known age and provenance and thus better understand geographic and temporal distributions of papermaking practices in Islamic countries

Quantitative chemical near-infrared hyperspectral imaging of Islamic paper

Heritage objects are well known for their compositional inhomogeneity due to materials and processes used in their production. Hyperspectral imaging is gaining importance in the field of heritage conservation by expanding spectroscopy to the examination of an entire surface of an object. This paper focuses on the application of near-infrared hyperspectral imaging to the characterisation of Islamic paper using a pushbroom HSI scanner in the 1000–2500 nm range to collect hyperspectral datacubes. A calibration target was devised using 105 samples from the well-characterised reference Islamic paper collection of the UCL Institute for Sustainable Heritage. Two material properties of Islamic paper were of interest: starch sizing and degree of polymerisation (DP). In addition to the developed discrimination and regression models using multivariate data analysis methods, a quantitative chemical map of the DP of an Islamic paper was generated as a case study for improved visualisation of the inhomogeneity of material properties, of value to researchers and conservators. As a case study, this research shows the wealth of valuable chemical information that near-infrared hyperspectral imaging could provide for diverse heritage applications in the future