Non-suicidal self-injury within the school context: Multilevel analysis of teachers' support and peer climate.

BACKGROUND: Recent studies regarding non-suicidal self-injury (NSSI) among adolescents have focused primarily on individual characteristics (e.g., depressive symptoms) and background factors (e.g., parental relationship), whereas less emphasis has been given to the role of school-related factors in NSSI. Therefore, the purpose of the current study was to explore the relationships between teachers' support, peer climate, and NSSI within the school context. METHODS: The sample consisted of 594 high school students nested within 27 regular classes (54.4% boys; mean age 14.96, SD=1.33 years). The students were evaluated for NSSI behaviors, perception of teacher support, peer climate, relationships with mothers, and depressive symptoms using validated scales. RESULTS: The primary analysis used hierarchical linear modeling (HLM), controlling for gender and age. The main findings indicated that teacher support was positively associated with NSSI at the classroom-level (OR=6.15, 95% CI=2.05-18.5) but negatively associated at the student-level (OR=0.66, 95% CI=0.49-0.89). There was a trend toward an association between positive peer climate and NSSI at the classroom-level (OR=0.43, 95% CI=0.18-1.05), while negative peer climate was associated with NSSI at the student-level (OR=1.37, 95% CI=1.00-1.87). CONCLUSIONS: School-related factors are associated with NSSI behaviors among students. Teachers and educators should focus on both individual-level and classroom-level perceptions of school context. Students who feel supported by their teachers and who are exposed to a positive peer climate are less likely to engage in NSSI.

Repeatability of cerebrospinal fluid constant rate infusion study.

OBJECTIVE: Infusion tests are important tools to assess cerebrospinal fluid (CSF)dynamics used in the preoperative selection of patients for shunt surgery, or to predict the scope of improvement from shunt revision. The aim of this study was to assess the repeatability of the key quantitative parameters describing CSF dynamics that are determined with infusion testing. MATERIALS AND METHODS: Eighteen patients in whom a constant infusion test was repeated within 102 days, without any intermediate surgical intervention, were studied. From each test baseline ICP, baseline pulse amplitude, outflow resistance, elastance coefficient and slope of the amplitude-pressure line were calculated and investigated with a regression and Bland-Altman analysis. RESULTS: Significant correlations (P < 0.01) were found for the outflow resistance (R = 0.96), the elastance coefficient (R = 0.778) and the slope of the amplitude-pressure line (R = 0.876). The estimated 95% confidence level for outflow resistance was 3 mmHg/ml min. Likewise, the elastance coefficient lay within a range of 0.16/ml and the slope of the amplitude-pressure line within 0.25. The most inconsistent parameter found were baseline ICP (R = 0.272) and baseline pulse amplitude (R = 0.171). CONCLUSION: The results of this study imply that the parameters resulting from an infusion study have to be considered within a range rather than as an absolute value.

An uncertainty budget for trace analysis by isotope-dilution ICP-MS with proper consideration of correlation.

Isotope-dilution mass spectrometry (IDMS) is considered to be a method without significant correction factors. It is also believed that this method is well understood. But unfortunately a large number of different uncertainty budgets have been published that consider different correction factors. These differences lead to conflicting combined uncertainties especially in trace analysis. It is described how the known correction factors must be considered in the uncertainty budget of values determined by IDMS combined with ICP-MS (ICP-IDMS). The corrections applied are dead time, background, interference, mass discrimination, blank correction and air buoyancy.IDMS measurements consist always of a series of isotope abundance ratio measurements and can be done according to different measurement protocols. Because the measurement protocols of IDMS are often rather sophisticated, correlations of influence quantities are difficult to identify. Therefore the measurement protocol has to be carefully considered in the specification of the measurand and a strategy is presented to properly account for these correlations. This will be exemplified for the estimation of mass fractions of platinum group elements (PGEs) and Re in the geological reference material UB-N (from CRPG-CNRS, Nancy in France) with ICP-IDMS. The PGEs with more than one isotope and the element Re are measured with on-line cation-exchange chromatography coupled to a quadrupole ICP-MS. All contents are below 10 microg kg(-1). Only osmium is separated from the matrix by direct sparging of OsO(4) into the plasma. This leads to transient signals for all PGEs and Re. It is possible to estimate the combined uncertainties and keep them favourably small despite the low contents, the transient signals and the sophisticated correction model.

Simplified method for the determination of Ru, Pd, Re, Os, Ir and Pt in chromitites and other geological materials by isotope dilution ICP-MS and acid digestion.

A method for the determination of low Ru, Pd, Re, Os, Ir and Pt abundances in geological reference materials by isotope dilution inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion in a high pressure asher (HPA-S) is presented. The digestion technique is similar to that using Carius tubes but easier to handle and reaches higher temperatures. Osmium can be determined as OsO4 with ICP-MS directly after digestion through a sparging technique. The remaining elements are preconcentrated by means of anion column chromatography. The resin is digested directly without elution leading to high yields but this causes problems if Zr is present at higher levels in the silicate rich materials. The analytical results for international platinum group element (PGE) reference materials, chromitite CHR-Bkg, basalt TDB-1 and gabbro WGB-1, are presented and compared with literature data, demonstrating the validity of the described method. Although higher in concentration, PGEs determined for reference material WGB-1 were worse than for TDB-1 indicating a more inhomogeneous distribution of the platinum group mineral phases. The low PGE abundance chromitite standard, CHR-Bkg, is likely to be homogeneous for Ru, Re, Os and Ir and is recommended as a reference material for the study of chromitites. Detection limits (3s x total procedure blank) range from 0.012 ng (Re and Os) to 0.77 ng (Pt), which could be further improved by applying higher quality acids.