High prevalence of vitamin A deficiency in Crohn's disease patients according to serum retinol levels and the relative dose-response test

AIM:To assess the vitamin A status of patients with Crohn's disease(CD) by evaluating serum retinol levels and the relative dose response(RDR) test(liver retinol stores).METHODS:Vitamin A nutritional status was measured by serum retinol obtained by high performance liquid chromatography and the RDR test for evaluation of the hepatic stores.Body composition was performed by densitometry by dual-energy X-ray absorptiometry.Vitamin A dietary intake was assessed from a semiquantitative food frequency questionnaire.RESULTS:This study included 38 CD patients and 33 controls.Low serum retinol concentrations were detected in 29% of CD patients vs 15% in controls(P < 0.005).The RDR test was positive in 37% of CD patients vs 12% in controls,which indicated inadequate hepatic vitamin A stores(P < 0.005).Individuals with hypovitaminosis A had lower BMI and body fat compared with those without this deficiency.There was no association between vitamin A deficiency and its dietary intake,ileal location,presence of disease activity and prior bowel resections.CONCLUSION:Patients with CD have higher prevalence of vitamin A deficiency,as assessed by two independent methods.

Analysis of relative wavelength response characterization and its effects on scanned-WMS gas sensing

Our recently proposed three-step method showed the promising potential to improve the accuracy of relative wavelength response(RWR) characterization in the wavelength-modulation spectroscopy(WMS) over the commonly used summation method.A detailed comparison of the three-step method and the summation method,for the wavelength-scanned WMS gas-sensing,was performed with different laser parameters(modulation indexes and scan indexes) and gas properties(pressures and concentrations).Simulation results show that the accuracy of the predicted gas parameters is strongly limited by the RWR characterization with large modulation index and high gas pressure conditions.Both fitting residuals of RWR and errors of predicted gas parameters from the recently proposed three-step method are nearly 2 orders of magnitude smaller than those from the summation method.In addition,the three-step method is further improved by introducing a coupling term for the 2^(nd) harmonic amplitude.Experiments with CO_(2) absorption transition at 6976.2026 cm^(-1) were conducted and validated the simulation analysis.The modified-three-step method presents an improved accuracy in RWR description with at least 5% smaller fitting residual for all conditions compared with the three-step method,although the deviation of the deduced CO_(2) concentrations between these two methods does not exceed 0.2%.

Relative Responses of Noble Gases Using a Pulsed Discharge Helium Photoionization Detector:Theoretical Calculation and Experimental Determination

The relative response factors（RRFs） for noble gas（Ng） were determined on a pulsed discharge helium photoionization detector. Using ab initio method, the atomic orbitals of noble gas were calculated and used to determine the number of ionizable electrons on the basis of the continuous emission of He2. The molar responses of noble gases is well correlated with the number of ionizable electrons.

Relative spectral response calibration using Ti plasma lines

This work introduces the branching ratio(BR) method for determining relative spectral responses,which are needed routinely in laser induced breakdown spectroscopy(LIBS). Neutral and singly ionized Ti lines in the 250–498 nm spectral range are investigated by measuring laser-induced micro plasma near a Ti plate and used to calculate the relative spectral response of an entire LIBS detection system. The results are compared with those of the conventional relative spectral response calibration method using a tungsten halogen lamp, and certain lines available for the BR method are selected. The study supports the common manner of using BRs to calibrate the detection system in LIBS setups.

BANDPASS FILTERING ANALYSIS WITH GAUSSIAN WEIGHTING FUNCTION IN TWO-DIMENSIONAL FIELDS

This paper examines the response of the bandpass filter with Gaussian weighting function to arbitrary two-dimensional fields and proposes a new concept of relative response function.Based on the properties of relative re- sponse function,satisfactory weighting parameters C_1 and C_2 are obtained.By studying two cases,the procedure of us- ing structure function curves to choose the maximum response wavelength is formulated.It is shown that bandpass fil- tering offers some improvements to the analysis and forecast of mesoscale weather processes.