•A multivariate analysis of cell wall FT-IR spectra was developed.•PCA and k-means distinguished the samples according to development stage and cultivar.•PLS models of galacturonic acid, cellulose ...and hemicellulose were built.•Possibility to adopt rapid spectroscopic methods in the control of compositional changes of plant cell wall.
The aim of this work was to quantitatively and qualitatively determine the composition of the cell wall material from apples during development by means of Fourier transform infrared (FT-IR) spectroscopy. The FT-IR region of 1500–800cm−1, containing characteristic bands for galacturonic acid, hemicellulose and cellulose, was examined using principal component analysis (PCA), k-means clustering and partial least squares (PLS). The samples were differentiated by development stage and cultivar using PCA and k-means clustering. PLS calibration models for galacturonic acid, hemicellulose and cellulose content from FT-IR spectra were developed and validated with the reference data. PLS models were tested using the root-mean-square errors of cross-validation for contents of galacturonic acid, hemicellulose and cellulose which was 8.30mg/g, 4.08% and 1.74%, respectively. It was proven that FT-IR spectroscopy combined with chemometric methods has potential for fast and reliable determination of the main constituents of fruit cell walls.
Quantum systems are typically characterized by the inherent fluctuation of their physical observables. Despite this fundamental importance, the investigation of the fluctuations in interacting ...quantum systems at finite temperature continues to pose considerable theoretical and experimental challenges. Here we report the characterization of atom number fluctuations in weakly interacting Bose-Einstein condensates. Technical fluctuations are mitigated through a combination of nondestructive detection and active stabilization of the cooling sequence. We observe fluctuations reduced by 27% below the canonical expectation for a noninteracting gas, revealing the microcanonical nature of our system. The peak fluctuations have near linear scaling with atom number ΔN_{0,p}^{2}∝N^{1.134} in an experimentally accessible transition region outside the thermodynamic limit. Our experimental results thus set a benchmark for theoretical calculations under typical experimental conditions.
Coronary computed tomography angiography-derived fractional flow reserve (CT-FFR) is a noninvasive application to evaluate the hemodynamic impact of coronary artery disease by simulating invasively ...measured FFR based on CT data. CT-FFR is based on the assumption of a normal coronary microvascular response. We assessed the diagnostic performance of a machine-learning based application for on-site computation of CT-FFR in patients with and without diabetes mellitus with suspected coronary artery disease. The study population included 75 diabetic and 276 nondiabetic patients who were enrolled in the MACHINE consortium. The overall diagnostic performance of coronary CT angiography alone and in combination with CT-FFR were analyzed with direct invasive FFR comparison in 110 coronary vessels of the diabetic group and in 415 coronary vessels of the nondiabetic group. Per-vessel discrimination of lesion-specific ischemia by CT-FFR was assessed by the area under the receiver operating characteristic curves. The overall diagnostic accuracy of CT-FFR in diabetic patients was 83% and in nondiabetic patients 75% (p = 0.088), showing improvement over the diagnostic accuracy of coronary CT angiography, which was 58% and 65% (p = 0.223), respectively. In addition, the diagnostic accuracy of CT-FFR was similar between diabetic and nondiabetic patients per stratified CT-FFR group (CT-FFR < 0.6, 0.6 to 0.69, 0.7 to 0.79, 0.8 to 0.89, ≥0.9). The area under the curves for diabetic and nondiabetic patients were also comparable, 0.88 and 0.82 (p = 0.113), respectively. In conclusion, on-site machine-learning CT-FFR analysis improved the diagnostic performance of coronary CT angiography and accurately discriminated lesion-specific ischemia in both diabetic and nondiabetic patients suspected of coronary artery disease.
In this international, multicenter study, using third-generation dual-source computed tomography (CT), we investigated the diagnostic performance of dynamic stress CT myocardial perfusion imaging ...(CT-MPI) in addition to coronary CT angiography (CTA) compared to invasive coronary angiography (ICA) and invasive fractional flow reserve (FFR).
CT-MPI combined with coronary CTA integrates coronary artery anatomy with inducible myocardial ischemia, showing promising results for the diagnosis of hemodynamically significant coronary artery disease in single-center studies.
At 9 centers in Europe, Japan, and the United States, 132 patients scheduled for ICA were enrolled; 114 patients successfully completed coronary CTA, adenosine-stress dynamic CT-MPI, and ICA. Invasive FFR was performed in vessels with 25% to 90% stenosis. Data were analyzed by independent core laboratories. For the primary analysis, for each coronary artery the presence of hemodynamically significant obstruction was interpreted by coronary CTA with CT-MPI compared to coronary CTA alone, using an FFR of ≤0.80 and angiographic severity as reference. Territorial absolute myocardial blood flow (MBF) and relative MBF were compared using C-statistics.
ICA and FFR identified hemodynamically significant stenoses in 74 of 289 coronary vessels (26%). Coronary CTA with ≥50% stenosis demonstrated a per-vessel sensitivity, specificity, and accuracy for the detection of hemodynamically significant stenosis of 96% (95% CI: 91%-100%), 72% (95% CI: 66%-78%), and 78% (95% CI: 73%-83%), respectively. Coronary CTA with CT-MPI showed a lower sensitivity (84%; 95% CI: 75%-92%) but higher specificity (89%; 95% CI: 85%-93%) and accuracy (88%; 95% CI: 84%-92%). The areas under the receiver-operating characteristic curve of absolute MBF and relative MBF were 0.79 (95% CI: 0.71-0.86) and 0.82 (95% CI: 0.74-0.88), respectively. The median dose-length product of CT-MPI and coronary CTA were 313 mGy·cm and 138 mGy·cm, respectively.
Dynamic CT-MPI offers incremental diagnostic value over coronary CTA alone for the identification of hemodynamically significant coronary artery disease. Generalized results from this multicenter study encourage broader consideration of dynamic CT-MPI in clinical practice. (Dynamic Stress Perfusion CT for Detection of Inducible Myocardial Ischemia SPECIFIC; NCT02810795)
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Urochloa panicoides is an annual weed of summer crops. In Argentina, in subhumid areas with monsoon rainfall, it germinates and establishes in a single flush. To (i) identify the environmental ...factors that modify its seed dormancy level and germination and (ii) quantify the parameters describing the thermal behaviour of the germination and emergence dynamics of this weed under non‐limiting water conditions, we established a set of germination experiments performed (i) under controlled conditions using seeds after ripened for 3 or 6 months in different thermal and hydric conditions and (ii) under field conditions, where the soil temperature was modified by applying different shading levels. Seed dormancy level remained high with 3 months after ripening in all treatments. After 6 months, seeds stored at 4°C in dry conditions did not germinate at any temperature, while seeds stored at 25°C in dry conditions and in situ germinated c. 20% and 60% respectively. Germination percentage was higher in seeds harvested before their natural dispersal. The base, optimum and maximum temperatures for seed germination were 6, 35 and 45°C respectively. Shading reduced the number of emerged seedlings, possibly by reducing the soil thermal amplitude. The results explained the dormancy‐breaking mechanism of U. panicoides that allows a high germination rate in the field when rainfall occurs.
Weed surveys were performed in commercial no-till glyphosate-tolerant soyabean crops in southern Entre Ríos province (Mesopotamic Pampas of Argentina) in 2005 and 2007, during the soyabean grain ...filling to maturity growth stages. The objectives were to describe the weed communities in fields recently introduced to crop production and to analyse the effect of the new cropping patterns on assemblages. The fields surveyed varied in the length of the no-till period (1-11 years), the previous crop and the soil productivity rating. Weed communities were described in terms of composition, constancy, life forms, morphotypes and (only during 2007) frequency. Tragia geraniifolia, Bidens subalternans, Sida spinosa, and Eryngium horridum were species associated with fields with more than 5 years of no-till glyphosate-tolerant crops. These fields had a significantly higher relative abundance of perennials (52% versus 32%) and of dicotyledons (66% versus 39%) than fields with less than 5 years of no-till. Previous crop and soil productivity affected weed community structure. Six species, five of them annuals, were associated with fields that had high yields and maize as the previous crop. In contrast, perennials and dicotyledons had the highest relative abundance when wheat-soyabean double cropping was the previous crop. The results show that changes in cropping systems acted as filters on functional traits, modifying the previous weed community assemblage. The information may be used to develop integrated crop-weed management strategies, leading to a reduction in the assemblage of highly competitive weed communities.
1. An early inhibition of germination in seeds of Silene gallica and Brassica campestris which were continuously exposed to the light environment under an establishing wheat canopy, was observed in ...two different experiments. Inhibition occurred c. 15 days after crop emergence, when the canopy leaf area index (LAI) was below one and the red (R):far-red (FR) ratio recorded under the canopy was well above 0.8. 2. This inhibitory effect was either overcome by filtering FR light through a solution of CuSO4 or could be artificially imposed by simulating the canopy with filters yeilding a R:FR ratio of 0.95 and 0.8. These results show that light subtly enriched with FR was the environmental factor regulating germination below the developing canopy. 3. Exposure to canopy-filtered light pulses of 1 h (presumably sufficient to saturate a low fluence response, LFR) did not inhibit seed germination. Moreover, such treatment promotes germination up to an extent similar to that previously observed in the laboratory after a saturating pulse of R light. Instead, prolonged exposures were required to inhibit germination. These results, together with the relatively high R:FR ratios measured below the canopy in early stages of its establishment, suggest that a high irradiance response (HIR) would be involved in such a regulation. 4. This capacity to detect small environmental light-quality modifications when exposed to high irradiances, would allow the seeds from these species to detect the presence of a canopy in the very early stages of its establishment and to stay in `safe' pre-germination phases when the probability of successful seedling establishment is low.
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