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1.
Contemporary methods of atrial flutter (AFL), atrial tachycardia (AT), and atrial fibrillation (AF) monitoring, although superior to the standard 12-lead ECG and symptom-based monitoring, are unable to accurately discriminate between AF, AFL and AT. Thus, there is a need to develop accurate, automated, and comprehensive atrial arrhythmia detection algorithms using standard ECG recorders. To this end, we have developed a sensitive and real-time realizable algorithm for accurate AFL and AT detection using any standard electrocardiographic recording. Our novel method for automatic detection of atrial flutter and atrial tachycardia uses a Bayesian approach followed by a high resolution time–frequency spectrum. We find the TQ interval of the electrocardiogram (ECG) corresponding to atrial activity by using a particle filter (PF), and analyze the atrial activity with a high resolution time–frequency spectral method: variable frequency complex demodulation (VFCDM). The rationale for using a high-resolution time–frequency algorithm is that our approach tracks the time-varying fundamental frequency of atrial activity, where AT is within 2.0–4.0 Hz, AFL is within 4.0–5.3 Hz and NSR is found at frequencies less than 2.0 Hz. For classifications of AFL (n = 22), AT (n = 10) and normal sinus rhythms (NSR) (n = 29), we found that our approach resulted in accuracies of 0.89, 0.87 and 0.91, respectively; the overall accuracy was 0.88.  相似文献   

2.
One of the major challenge in the detection of mental states is improving the accuracy of brain activity-based detectors with additional information from extracranial signals. We assessed the suitability, for real-time mental fatigue detection, of EEG, EOG and ECG measurements, taken separately or together. Thirteen subjects performed six blocks of switching tasks. For each participant, the block with the lowest error rate from the first two blocks and the block with the highest error rate from the last three blocks were discriminated with a machine learning algorithm (support vector machine). The classification scores obtained with ECG or EOG were greater than would be expected by chance (>50%) for time windows of at least 8 s. EEG was the best single mode of detection, with classification scores ranging from 80 ± 3% with a 4 s time window to 94 ± 2% with a 30 s time window. The addition of ECG and EOG features to EEG features significantly increased classification scores for short time windows (e.g., to 86 ± 3% with a 4 s time window, p < 0.001). For short time windows (up to 12 s), ECG significantly increased the discriminatory power of EEG, whereas EOG did not. These results demonstrate that mental state detection on the basis of extracerebral measurements is feasible and that a combination of EEG and ECG is particularly appropriate for the rapid detection of mental fatigue.  相似文献   

3.
The R-peak detection is crucial in all kinds of electrocardiogram (ECG) applications. However, almost all existing R-peak detectors suffer from the non-stationarity of both QRS morphology and noise. To combat this difficulty, we propose a new R-peak detector, which is based on the new preprocessing technique and an automated peak-finding logic. In this paper, we first demonstrate that the proposed preprocessor with a Shannon energy envelope (SEE) estimator is better able to detect R-peaks in case of wider and small QRS complexes, negative QRS polarities, and sudden changes in QRS amplitudes over that using the absolute value, energy value, and Shannon entropy features. Then we justify the simplicity and robustness of the proposed peak-finding logic using the Hilbert-transform (HT) and moving average (MA) filter. The proposed R-peak detector is validated using the first-channel of the 48 ECG records of the MIT-BITH arrhythmia database, and achieves average detection accuracy of 99.80%, sensitivity of 99.93% and positive predictivity of 99.86%. Various experimental results show that the proposed R-peak detection method significantly outperforms other well-known methods in case of noisy or pathological signals.  相似文献   

4.
The extensive input of chemical insecticides for pest control is considered as a serious risk to the environment, and the ecological disturbance of chemical insecticides has both positive and negative effects on complex agro-ecosystems. This paper proposed an indicator based on ecological two-sidedness theory and Shannon entropy, which is intended for analyzing informational complexity in a decision network of the chemical insecticide pollution management. The results indicated that the order of the value of RCC/CP index (where the RCC/CP index matrix WCC/CP is defined as the index optimization matrix of comprehensive cost divided by the index optimization matrix of comprehensive profit) for three insect pest-controlling strategies in scallion fields was “applying frequency vibration lamps and environment-friendly insecticides 8 times” (0.8714) < “applying trap devices and environment-friendly insecticides 9 times” (0.8858) < “applying common insecticides 15 times” (0.9077). The treatment “applying frequency vibration lamps and environment-friendly insecticides 8 times” was recognized as the optimal strategy for chemical insecticide pollution management in scallion fields in Shanghai, China. The results demonstrate that our proposed ecological indicator might arouse the interest of policy makers and eco-environmentalists who seek to minimize the use of chemicals, and the farmers who hope to optimize pest-controlling strategies in practice.  相似文献   

5.
With Candida antarctica lipase B (CALB)-catalyzed alcoholysis of (R,S)-naproxenyl 1,2,4-triazolide at the optimal conditions (i.e. anhydrous MTBE as the solvent, and methanol as the acyl acceptor at 45 °C) as the model system, the enzyme enantioselectivity in terms of VR/VS = 105.8 and specific activity for the fast-reacting (R)-azolide VR/(Et) = 0.979 mmol/(h g) were greatly improved in comparison with VR/VS = 8.0 and VR/(Et) = 0.113 mmol/(h g) of using (R,S)-naproxenyl 2,2,2-trifluoroethyl ester as the substrate. The resolution strategy was successfully extended to other (R,S)-profenyl 1,2,4-triazolides and lipases from Candida rugosa (Lipase MY) and Carica papaya (CPL) having opposite enantioselectivity to CALB. Moreover, the kinetic constants were estimated, compared with those obtained via hydrolysis, and employed for modeling time-course conversions of (R,S)-naproxenyl 1,2,4-triazolide in anhydrous MTBE. The advantages of easy substrate preparation, high enzyme reactivity and enantioselectivity, as well as easy product separation from the remaining substrate via reactive extraction demonstrate merits of using (R,S)-azolides but not the corresponding esters for the alcoholytic resolution.  相似文献   

6.
Secoisolariciresinol diglucosides (SDGs) (S,S)-SDG-1 (major isomer in flaxseed) and (R,R)-SDG-2 (minor isomer in flaxseed) were synthesized from vanillin via secoisolariciresinol (6) and glucosyl donor 7 through a concise route that involved chromatographic separation of diastereomeric diglucoside derivatives (S,S)-8 and (R,R)-9. Synthetic (S,S)-SDG-1 and (R,R)-SDG-2 exhibited potent antioxidant properties (EC50 = 292.17 ± 27.71 μM and 331.94 ± 21.21 μM, respectively), which compared well with that of natural (S,S)-SDG-1 (EC50 = 275.24 ± 13.15 μM). These values are significantly lower than those of ascorbic acid (EC50 = 1129.32 ± 88.79 μM) and α-tocopherol (EC50 = 944.62 ± 148.00 μM). Compounds (S,S)-SDG-1 and (R,R)-SDG-2 also demonstrated powerful scavenging activities against hydroxyl [natural (S,S)-SDG-1: 3.68 ± 0.27; synthetic (S,S)-SDG-1: 2.09 ± 0.16; synthetic (R,R)-SDG-2: 1.96 ± 0.27], peroxyl [natural (S,S)-SDG-1: 2.55 ± 0.11; synthetic (S,S)-SDG-1: 2.20 ± 0.10; synthetic (R,R)-SDG-2: 3.03 ± 0.04] and DPPH [natural (S,S)-SDG-1: EC50 = 83.94 ± 2.80 μM; synthetic (S,S)-SDG-1: EC50 = 157.54 ± 21.30 μM; synthetic (R,R)-SDG-2: EC50 = 123.63 ± 8.67 μM] radicals. These results confirm previous studies with naturally occurring (S,S)-SDG-1 and establish both (S,S)-SDG-1 and (R,R)-SDG-2 as potent antioxidants and free radical scavengers for potential in vivo use.  相似文献   

7.
Long-term climatic changes related to solar forcing were examined using millennium-scale palaeoclimatic reconstructions from the Central Asian mountain region, i.e. summer temperature records for the Tien Shan mountains and precipitation records for the Tibetan Plateau. The reconstructions were based on juniper tree-ring width records, i.e. Juniperus turkestanica for the Tien Shan and Sabina przewalskii for the Tibetan Plateau. The data were processed using spectral and wavelet analysis and filtered in the frequency range related to major solar activity periodicities. The results obtained for various tree-ring chronologies indicate palaeoclimatic oscillations in the range of the de Vries (~ 210-year) solar cycles through the last millennium.The quasi-200-year variations revealed in the palaeoclimatic reconstructions correlate well (R2 = 0.58–0.94) with solar activity variations (Δ14C variations). The quasi-200-year climatic variations have also been detected in climate-linked processes in Asia, Europe, North and South America, Australia, and the Arctic and Antarctica. The results obtained point to a pronounced influence of solar activity on global climatic processes.Analysis has shown that climate response to the long-term global solar forcing has a regional character. An appreciable delay in the climate response to the solar signal can occur (up to 150 years). In addition, the sign of the climate response can differ from the solar signal sign. The climate response to long-term solar activity variations (from 10s to 1000s years) manifests itself in different climatic parameters, such as temperature, precipitation and atmospheric and oceanic circulation. The climate response to the de Vries cycle has been found to occur not only during the last millennia but also in earlier epochs, up to hundreds of millions years ago.  相似文献   

8.
The study investigated the suitability of stage of maturity and botanical fractions of whole crop rice (WCR) to predict yield and nutritive value of ensiled WCR for dairy cows. Eight varieties of WCR (i.e., Akichikara, Fukuhibiki, Habataki, Hamasari, Hokuriku 168, Kusanami, Tamakei 96, Yumetoiro) were harvested at four stages of maturity (i.e., 10, 22, 34, 45 days after flowering [DAF]) and ensiled. Dry matter (DM) yield at each harvest was determined. Silage samples were fractionated into four botanical fractions being: leaf blade, leaf sheath, stem and head. Silage samples were also analyzed for chemical composition, fermentation characteristics, in situ DM and N disappearance. Metabolizable energy (ME) and metabolizable protein (MP) content of samples were estimated according to Terada et al. (1988) and AFRC (1993), respectively. Relationships between maturity or proportions of botanical fractions and contents of WCR silage in terms of DM, ME and MP, and their yields, were estimated by correlation and regression analysis. Stage of maturity was positively related (P<0.001) to ME content (R2 = 0.46; y = 4.53 + 0.08X) and MP content (R2 = 0.56; y = 22.26 + 0.76X), and DM yield (R2 = 0.63; y = 9.21 + 0.12X), ME yield (R2 = 0.68, y = 36931 + 1708X) and MP yield (R2 = 0.72, y = 161.0 + 14.15X) of WCR. Proportion of leaf was negatively related to yields and nutritive value of ensiled WCR, whilst proportion of head was positively related (P<0.05 to <0.001). Proportion of head was best related to the ME content (R2 = 0.72; y = 3.26 + 0.009X), MP content (R2 = 0.72; y = 12.31 + 0.079X), and DM yield (R2 = 0.41; y = 9.02 + 0.009X), ME yield (R2 = 0.76, y = 19494 + 165.5X), and MP yield (R2 = 0.75, y = 34.37 + 1.32X) of WCR. Results suggest that to optimize yield and nutritive value, WCR should be ensiled within 40 DAF and the proportion of head should be equal to or more than 500 g per kg DM of WCR silage. Stage of maturity and proportion of head of WCR predict yields of DM, ME and MP of WCR, and their contents, in WCR silage with acceptable accuracy. However, these relationships need to be validated using large data sets and in vivo studies.  相似文献   

9.
《Process Biochemistry》2007,42(9):1319-1325
A two-step enzymatic resolution process for production of (R)- and (S)-glycidyl butyrate was investigated and the lipases were screened. The first step involved a hydrolysis of (R,S)-glycidyl butyrate catalyzed by porcine pancreatic lipase (S-favored) with an E of 21 for production of (R)-glycidyl butyrate (13.2 mmol, 98% ee, 36% yield) under the optimal conditions (pH 7.4, 30 °C, 30 mg/ml CTAB). Then, the recovered (R)-enriched glycidol (19.8 mmol, 65% ee, 56% yield) was used for transesterification catalyzed by Novozym 435 (R-favored) with an E of 69 to obtain (S)-glycidyl butyrate (15.1 mmol, 98% ee, 42% yield) under the optimum conditions (aW = 0.24, n-heptane, 80 min).  相似文献   

10.
The cytotoxic activities of sesquilignans, (7S,8S,7′R,8′R)- and (7R,8R,7′S,8′S)-morinol A and (7S,8S,7′S,8′S)- and (7R,8R,7′R,8′R)-morinol B were compared, showing no significant difference between stereoisomers (IC50 = 24–35 μM). As a next stage, the effect of substituents at 7, 7′, and 7″-aromatic ring on the activity was evaluated to find out the higher activity of (7S,8S,7′R,8′R)-7,7′,7″-phenyl derivative 18 (IC50 = 6–7 μM). In the research on the structure–activity relationship of 7″-position of (7S,8S,7′R,8′R)-7,7′,7″-phenyl derivative 18, the most potent compounds were 7,7′,7″-phenyl derivative 18 (IC50 = 6 μM) against HeLa cells. Against HL-60 cells, 7″-(4-nitrophenyl)-7,7′-phenyl derivative 33 and 7″-hexyl-7,7′-phenyl derivative 37 (IC50 = 5 μM) showed highest activity. We discovered the compounds showed four to sevenfold potent activity than that of natural (7S,8S,7′R,8′R)-morinol A. It was also confirmed that the 7′-benzylic hydroxy group have an important role for exhibiting activity, on the other hand, the resonance system of cinnamyl structure is not crucial for the potent activity.  相似文献   

11.
PurposeThis study was to assess the clinical relevance of the blood granulocytes to lymphocytes (G/L) ratio as an early marker of surgical stress in patients with colorectal cancer.MethodsThirty-three patients with colorectal cancer were prospectively to undergo laparoscopic-assisted (n = 12) or open (n = 21) surgical resection. Granulocyte and lymphocyte counts were used to calculate the G/L ratios in blood samples from all patients before the operation and post-operatively on days 1, 3 and 7. Additionally, serum inflammatory cytokines, interleukin (IL)-1β, IL-6, IL-8, tumour necrosis factor (TNF)-α, granulocyte colony-stimulating factor (G-CSF) and macrophage (M)-CSF were assayed as markers of surgical stress.ResultsSeven of 33 patients developed unexpected complications. Serum IL-6 (P < 0.0001), G-CSF (P = 0.0257), and M-CSF (P < 0.0001) were higher on day 1 vs before the operation. Similarly, the G/L ratios were higher on days 1–3 vs before the operation (P < 0.0001) and then gradually decreased together with the surgical stress levels. The G/L ratios and the numbers of granulocytes and lymphocytes in the blood showed no correlation with serum IL-1β or TNF-α. In contrast, the G/L ratios and the numbers of granulocytes in the blood showed significant correlation with IL-6 (Rs = 0.710, P < 0.0001, Rs = 0.653, P < 0.0001, respectively), with G-CSF (Rs = 0.626, P < 0.0001, Rs = 0.578, P < 0.0001), with M-CSF (Rs = 0.470, P < 0.0001, Rs = 0.372, P < 0.0001). However, the number of lymphocytes showed inverse correlation with IL-6 (Rs = ?0.493, P < 0.0001), G-CSF (Rs = ?0.440, P < 0.0001) and M-SCF (Rs = ?0.443, P < 0.0001).ConclusionThe G/L ratio appears to be a simple and clinically relevant parameter for the assessment of perioperative stress in patients undergoing colorectal surgery.  相似文献   

12.
This study focused on understanding the termite traveling behavior. Artificial tunnels with different curvatures and base surface roughness were constructed. Each tunnel was 50 mm in length, with widths of W (W = 2, 3, or 4 mm). The distance between the two ends of the tunnel was D (D = 20, 30, 40, or 50 mm). A higher value of D means a lower curvature. The roughness, R (R = 60, 120, 240 and ∞), was generated by uniformly sanding the substrate with a sanding machine. A higher R value means a finer base surface. The symbol ∞ represents a smooth surface. Time (τ) taken by a termite to pass through the tunnel was measured. τ was longer in tunnels with a smooth surface compared with the tunnels with a rough surface. When W = 2, there was no effect of the roughness on speed. This is because the narrow tunnel width diluted the effects of the smoothness of the surface. When W = 3, τ was statistically shorter for R = 240, than for R = 60 and 120. This suggests that an appropriate surface roughness could positively contribute to the traveling speed.  相似文献   

13.
Megastigmane glycosides (15) together with seven (612) related known compounds were isolated from the whole plants of Gynostemma pentaphyllum. The structures were elucidated by means of spectroscopic methods, including 2D NMR, HR-ESIMS, and circular dichroism (CD), as well as chemical transformations to be (3R, 4R, 5S, 6S, 7E)-3,4,6-trihydroxymegastigmane-7-en-9-one-3-O-β-d-glucopyranoside (gynostemoside A, 1), (3S, 4S, 5R, 6R, 7E, 9R)-3,4,6,9-tetrahydroxymegastigmane-7-en-3-O-β-d-glucopyranoside (gynostemoside B, 2), (3S, 4S, 5S, 6S, 7E, 9R)-3,4,9-trihydroxymegastigmane-7-en-9-O-β-d-glucopyranoside (gynostemoside C, 3), (3S, 4S, 5S, 6S, 7E, 9R)-3,4,9-trihydroxymegastigmane-7-en-3-O-β-d-glucopyranoside (gynostemoside D, 4), and (3S, 4S, 5S, 6S, 7E, 9R)-3,4,9-trihydroxymegastigmane-7-en-4-O-β-d-glucopyranoside (gynostemoside E, 5), respectively.  相似文献   

14.
Abdominal fat accumulation is a major risk factor for cardiometabolic morbidity and mortality. The purpose of the study is to assess the possibility of developing accurate estimation equations based on body measurements to determine total abdominal (TFA), subcutaneous (SFA) and visceral fat area (VFA). Hungarian volunteers (n = 198) aged between 20 and 81 years were enrolled in the study, which was conducted between July and November 2014. All persons underwent anthropometric measurements and computer tomographic (CT) scanning. Sex-specific multiple linear regression analyses were conducted in a subgroup of 98 participants to generate estimation models, then Bland–Altman's analyses were applied in the cross-validation group to compare their predictive efficiency. The variables best predicting VFA were hip circumference, calf circumference and waist-to-hip ratio (WHR) for males (R2 = 0.713; SEE = 5602.1 mm2) and sagittal abdominal diameter (SAD), WHR, thigh circumference and triceps skinfold for females (R2 = 0.845; SEE = 3835.6 mm2). The SFA prediction equation included SAD, thigh circumference and abdominal skinfold for males (R2 = 0.848; SEE = 4124.1 mm2), body mass index and thigh circumference for females (R2 = 0.861; SEE = 5049.7 mm2). Prediction accuracy was the highest in the case of TFA: hip circumference and WHR for males (R2 = 0.910; SEE = 5637.2 mm2), SAD, thigh circumference and abdominal skinfold for females (R2 = 0.915; SEE = 6197.5 mm2) were used in the equations. The results suggested that deviations in the predictions were independent of the amount of adipose tissue. Estimation of abdominal fat depots based on anthropometric traits could provide a cheap, reliable method in epidemiologic research and public health screening to evaluate the risk of cardiometabolic events.  相似文献   

15.
Green roofs can notably modify the thermal properties of the building envelope and adjacent air to bring environmental benefits. This study investigates the heat flux dynamics of the tropical green roof ecosystem to provide a scientific basis for design and management. Green roof experimental plots were established to monitor the total solar radiation, net radiation, and micrometeorological parameters. The data permit calculation of sensible and latent heat fluxes using the Bowen ratio energy balance (BREB) method. The results demonstrated the life cycle characteristics of heat flux components. The dynamic changes of sensible (H), latent (λE) and soil (G) heat fluxes were denoted by single-peak quadratic curves. Net radiation (Rn) was largely determined by quantity and variation trends of λE, reaching at 1300 h a maximum λE of 655 W m?2 and maximum H of 369 W m?2. Temporal heat-flux fluctuations were strongly correlated with meteorological variables. Extreme values of H and λE correlated well with precipitation and temperature (R2 = 0.78). Dynamics of heat-flux magnitude and partitioning demonstrated notable differences by daily and season periods. They displayed considerable variations in flux partitioning, with Bowen ratios strongly correlated with weather conditions and vegetation types. The energy budget of the green roof ecosystem is unbalanced with a heat loss of about 15.5% caused by soil and canopy heat reserve. The passive indoor cooling effect under the green roof is attributed to the unbalanced energy closure.  相似文献   

16.
We synthesized four types of arginine-based amphipathic nonapeptides, including two homochiral peptides, R-(l-Arg-l-Arg-Aib)3-NH2 (R = 6-FAM-β-Ala: FAM-1; R = Ac: Ac-1) and R-(d-Arg-d-Arg-Aib)3-NH2 (R = 6-FAM-β-Ala: ent-FAM-1; R = Ac: ent-Ac-1); a heterochiral peptide, R-(l-Arg-d-Arg-Aib)3-NH2 (R = 6-FAM-β-Ala: FAM-2; R = Ac: Ac-2); and a racemic mixture of diastereomeric peptides, R-(rac-Arg-rac-Arg-Aib)3-NH2 (R = 6-FAM-β-Ala: FAM-3; R = Ac: Ac-3), and then investigated the relationship between their secondary structures and their ability to pass through cell membranes. Peptides 1 and ent-1 formed stable one-handed α-helical structures and were more effective at penetrating HeLa cells than the non-helical peptides 2 and 3.  相似文献   

17.
《Palaeoworld》2020,29(3):617-628
Six Tsuga ovuliferous/seed cone impression fossils were discovered from the late Eocene (34.6 ± 0.8 Ma) Lawula Formation in Mangkang County, eastern Tibet and the early Oligocene (32 ± 1 Ma) lacustrine deposits in Lühe Basin, Nanhua County, Yunnan Province. These two fossil sites are both located in southwestern China, ∼800 km apart from each other. These fossils represent the oldest records of this genus in southwestern China, even earliest reliable macrofossil records of this genus in the world. These well-preserved seed cones provide sufficient materials for the establishment of Tsuga asiatica Wu et Zhou n. sp. to accommodate five specimens, leaving one to be assigned to T. cf. dumosa Eichler (cf. Wu et Zhou). Both qualitative and quantitative comparisons with other cone fossils and cones of all living species of the genus suggested that T. asiatica shares more similarities with one of the basal species of the genus T. heterophylla. The discovery of late Paleogene macrofossil records of Tsuga in southwestern China supports the previous hypothesis of the early disposal routes of this coniferous genus predicted by phylogenetic analysis. The elevation ranges and the climate requirements of living species that are closely related to our fossils suggest that the southeastern edge of the Qinghai-Tibetan Plateau should be much warmer, and wetter in late Paleogene than nowadays.  相似文献   

18.
The purpose of this study was to explore the role of visual and proprioceptive feedback in upper limb posture control in fibromyalgia (FM) and to assess the coherence between acceleration measurements of upper limb micro movements and surface electromyography (sEMG) of shoulder muscle activity (upper trapezius and deltoid). Twenty-five female FM patients and 25 age- and sex-matched healthy controls (HCs) performed three precision motor tasks: (1) maintain a steady shoulder abduction angle of 45° while receiving visual feedback about upper arm position and supporting external loads (0.5, 1, or 2 kg), (2) maintain the same shoulder abduction angle without visual feedback (eyes closed) and no external loading, and (3) a joint position sense test (i.e., assessment of proprioceptive accuracy). Patients had more extensive increase in movement variance than HCs when visual feedback was removed (P < 0.03). Proprioceptive accuracy was related to movement variance in HCs (R  0.59, P  0.002), but not in patients (R  0.25, P  0.24). There was no difference between patients and HCs in coherence between sEMG and acceleration data. These results may indicate that FM patients are more dependent on visual feedback and less reliant on proprioceptive information for upper limb posture control compared to HCs.  相似文献   

19.
According to the green wave hypothesis, herbivores follow the flush of spring growth of forage plants during their spring migration to northern breeding grounds. In this study we compared two green wave indices for predicting the timing of the spring migration of avian herbivores: the satellite-derived green wave index (GWI), and an index of the rate of acceleration in temperature (GDDjerk). The GWI was calculated from MODIS normalized difference vegetation index (NDVI) satellite imagery and GDDjerk from gridded temperature data using products from the global land data assimilation system (GLDAS). To predict the timing of arrival at stopover and breeding sites, we used four years (2008–2011) of tracking data from 12 GPS-tagged barnacle geese, a long-distance herbivorous migrant, wintering in the Netherlands, breeding in the Russian Arctic. The stopover and breeding sites for these birds were identified and the relations between date of arrival with the date of 50% GWI and date of peak GDDjerk at each site were analyzed using mixed effect linear regression. A cross-validation method was used to compare the predictive accuracy of the GWI and GDDjerk indices. Significant relationships were found between the arrival dates at the stopover and breeding sites for the dates of 50% GWI as well as the peak GDDjerk (p < 0.01). The goose arrival dates at both stopover and breeding sites were predicted more accurately using GWI (R2cv = 0.68, RMSDcv = 5.9 and  R2cv= 0.71, RMSDcv = 3.9 for stopover and breeding sites, respectively) than GDDjerk. The GDDjerk returned a lower accuracy for prediction of goose arrival dates at stopover ( R2cv = 0.45, RMSDcv = 7.79) and breeding sites (R2cv = 0.55, RMSDcv = 4.93). The positive correlation between the absolute residual values of the GDDjerk model and distance to the breeding sites showed that this index is highly sensitive to latitude. This study demonstrates that the satellite-derived green wave index (GWI) can accurately predict the timing of goose migration, irrespective of latitude and therefore is suggested as a reliable green wave index for predicting the timing of avian herbivores spring migration.  相似文献   

20.
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