Quantitative Ratio Research Articles

The Differences of Quantitative Flow Ratio in Coronary Artery Stenosis with or without Atrial Fibrillation.

Quantitative flow ratio (QFR) is a new method for the assessment of the extent of coronary artery stenosis. But it may be obscured by the cardiac remodeling and abnormal blood flow of the coronary artery when encountering atrial fibrillation (AF). The present study aimed to examine the impact of these changed structures and blood flow of coronary arteries on QFR results in AF patients. Methods and Results. We evaluated QFR in 223 patients (112 patients with AF; 111 non-AF patients served as controls) who had undergone percutaneous coronary intervention (PCI) due to severe stenoses in coronary arteries. QFR of the target coronary was determined according to the flow rate of the contrast agent. Results showed that AF patients had significantly higher QFR values than control (0.792 ± 0.118 vs. 0.685 ± 0.167, p < 0.001). We further analyzed local QFR around the stenoses (0.858 ± 0.304 vs. 0.756 ± 0.146, p=0.002), residual QFR (0.958 ± 0.055 vs. 0.929 ± 0.093, p=0.005), and index QFR (0.807 ± 0.108 vs. 0.713 ± 0.152, p < 0.001) in these two groups of patients with and without AF. Further analysis revealed that QFR in AF patients was negatively correlated with coronary flow velocity (R = -0.22, p=0.02) and area of stenosis (R = -0.70, p < 0.001) but positively correlated with the minimum lumen area (MLA) (R = 0.47, p < 0.001). Conclusion. AF patients with coronary artery stenosis have higher QFR values, which are associated with decreased blood flow velocity, smaller stenosis, and larger MLA in AF patients upon cardiac remodeling.

Network of Settlements in Novosibirsk District in 1920s: Population, Structure and Development Features

The study analyzes the population, typology, and size of settlements in the Novosibirsk district, which was one of the administrative-territorial units of the Siberian region in 1925—1930. The peculiarities of the development of the settlement network in this district are determined in comparison with neighboring districts. Data on the quantitative ratio of settlements of different types, their household and population composition are presented for the first time, and continuity and transformation in the development of the settlement system in the district are traced. The relevance of the study lies not only in the poorly studied nature of the topic but also in the possibility of using historical experience from previous generations to build an effective agricultural policy and revive the Russian village in its modern stage of development. The novelty of the study lies in the analysis of the functioning of the settlement network in the early years of Soviet power, including the typical structure of its units, the average number of peasant households in settlements of different types, and the placement of mono-ethnic settlements in the Novosibirsk district. A new trend has been noted in transforming rural settlements into urban ones, expressed in a refusal to make purely administrative decisions on this issue in favor of taking into account the sequential evolution of a specific settlement.

QFR Assessment and Prognosis After Nonculprit PCI in Patients With Acute Myocardial Infarction

BackgroundComplete revascularization using either angiography-guided or fractional flow reserve (FFR)-guided strategy can improve clinical outcomes in patients with acute myocardial infarction (AMI) and multivessel disease. However, there is concern that angiography-guided percutaneous coronary intervention (PCI) may result in un-necessary PCI of the non–infarct-related artery (non-IRA), and its long-term prognosis is still unclear. ObjectivesThis study sought to evaluate clinical outcomes after non-IRA PCI according to the quantitative flow ratio (QFR). MethodsWe performed post hoc QFR analysis of non-IRA lesions of AMI patients enrolled in the FRAME-AMI (FFR Versus Angiography-Guided Strategy for Management of AMI With Multivessel Disease) trial, which randomly allocated 562 patients into either FFR-guided PCI (FFR ≤0.80) or angiography-guided PCI (diameter stenosis >50%) for non-IRA lesions. Patients were classified by non-IRA QFR values into the QFR ≤0.80 and QFR >0.80 groups. The primary outcome was a major adverse cardiac event (MACE), a composite of cardiac death, myocardial infarction, and repeat revascularization. ResultsA total of 443 patients (552 lesions) were eligible for QFR analysis. Of 209 patients in the angiography-guided PCI group, 30.0% (n = 60) underwent non-IRA PCI despite having QFR >0.80 in the non-IRA. Conversely, only 2.7% (n = 4) among 209 patients in the FFR-guided PCI group had QFR >0.80 in the non-IRA. At a median follow-up of 3.5 years, the rate of MACEs was significantly higher among patients with non-IRA PCI despite QFR >0.80 than in patients with deferred PCI for non-IRA lesions (12.9% vs 3.1%; HR: 4.13; 95% CI: 1.10-15.57; P = 0.036). Non-IRA PCI despite QFR >0.80 was associated with a higher risk of non-IRA MACEs than patients with deferred PCI for non-IRA lesions (12.9% vs 2.1%; HR: 5.44; 95% CI: 1.13-26.19; P = 0.035). ConclusionsIn AMI patients with multivessel disease, 30.0% of angiography-guided PCI resulted in un-necessary PCI for the non-IRA with QFR >0.80, which was significantly associated with an increased risk of MACEs than in those with deferred PCI for non-IRA lesions. (FFR Versus Angiography-Guided Strategy for Management of AMI With Multivessel Disease [FRAME-AMI] ClinicalTrials.gov number; NCT02715518)

TCT-343 Prognostic Impact of Morpho-Functional Assessment With Quantitative Flow Ratio and Optical Coherence Tomography in Patients With Acute Coronary Syndromes

TCT-343 Prognostic Impact of Morpho-Functional Assessment With Quantitative Flow Ratio and Optical Coherence Tomography in Patients With Acute Coronary Syndromes

TCT-151 Diagnostic Accuracy of Murray Law–Based Quantitative Flow Ratio in Patients With Severe Aortic Stenosis Undergoing Transcatheter Aortic Valve Replacement

TCT-151 Diagnostic Accuracy of Murray Law–Based Quantitative Flow Ratio in Patients With Severe Aortic Stenosis Undergoing Transcatheter Aortic Valve Replacement

TCT-342 Prognostic Implications of Quantitative Flow Ratio and Adverse Plaque Characteristics in Intravascular Ultrasound-Guided Revascularization Strategy

TCT-342 Prognostic Implications of Quantitative Flow Ratio and Adverse Plaque Characteristics in Intravascular Ultrasound-Guided Revascularization Strategy

Quantitative flow ratio derived pullback pressure gradient and CZT-SPECT measured longitudinal flow gradient for hemodynamically significant coronary artery disease

BackgroundWhether physiological coronary diffuseness assessed by quantitative flow reserve (QFR) pullback pressure gradient (PPG) correlates with longitudinal myocardial blood flow (MBF) gradient and improves diagnostic performances for myocardial ischemia remains unknown. Methods and resultsMBF was measured in mL g−1 min−1 with 99mTc-MIBI CZT-SPECT at rest and stress, corresponding myocardial flow reserve (MFR = MBF stress/MBF rest) and relative flow reserve (RFR = MBF stenotic area/MBF reference) were calculated. Longitudinal MBF gradient was defined as apical and basal left ventricle MBF gradient. △longitudinal MBF gradient was calculated by longitudinal MBF gradient at stress and rest. QFR-PPG was acquired from virtual QFR pullback curve. QFR-PPG significantly correlated with hyperemic longitudinal MBF gradient (r = 0.45, P = 0.007) and △longitudinal MBF gradient (stress-rest) (r = 0.41, P = 0.016). Vessels with lower RFR had lower QFR-PPG (0.72 vs. 0.82, P = 0.002), hyperemic longitudinal MBF gradient (1.14 vs. 2.22, P = 0.003) and △longitudinal MBF gradient (0.50 vs. 1.02, P = 0.003). QFR-PPG, hyperemic longitudinal MBF gradient and △longitudinal MBF gradient showed comparable diagnostic performances for predicting decreased RFR (area under curve [AUC]: 0.82 vs. 0.81 vs. 0.75, P = NS) or QFR (AUC: 0.83 vs. 0.72 vs. 0.80, P = NS). In addition, QFR-PPG and QFR in combination showed incremental value compared with QFR for predicting RFR (AUC = 0.83 vs. 0.73, P = 0.046, net reclassification index = 0.508, P = 0.001). ConclusionQFR-PPG significantly correlated with longitudinal MBF gradient and △longitudinal MBF gradient when used for physiological coronary diffuseness assessment. All three parameters had high accuracy in predicting RFR or QFR. Adding physiological diffuseness assessment increased accuracy for predicting myocardial ischemia.

TCT-208 Comparison of Fractional Flow Reserve and Quantitative Flow Ratio After Successful Percutaneous Coronary Intervention in Patients With Chronic Total Occlusion

TCT-208 Comparison of Fractional Flow Reserve and Quantitative Flow Ratio After Successful Percutaneous Coronary Intervention in Patients With Chronic Total Occlusion

Комплексне хромоалітування вуглецевих сталей в середовищі хлору

The authors investigated the influence of the nature of the chlorine-containing activator on the structure, chemical composition, and some properties of diffusion layers formed during complex chromium-alloying of carbon steels in a chlorine environment. On the basis of thermodynamic calculations, the quantitative ratio of saturating elements (chromium and aluminum) and rational coating temperatures were determined. It was determined that for the complex chromoalitization of steels, an increased amount of chromium in the composition of the saturating mixture is necessary. Based on the data obtained, the temperature intervals for complex chromoalitization of carbon steels in a chlorine environment were recommended to be 800-1100°C. Coatings were applied at a temperature of 950-1050°C for 2 hours in a saturating mixture of the following composition: 45 % wt. chromium, 5 % wt. aluminum, 47 % wt. Al2O3 and 3.0 % by weight of the activator. The chlorine-containing compounds NH4Cl and NiCl2 were used as activators. The structure, chemical composition, and distribution of microhardness along the cross-section of the obtained chrome-aluminum coatings were investigated. It was found that the distribution of structural components in both types of coatings obtained at a temperature of 950 °C is almost identical. At the same time, the structure of the diffusion zone obtained by using NiCl2 as an activator shows the presence of a two-phase layer of dark inclusions, the main component of which is small columnar crystals. The thickness of the obtained coatings is 23-32 microns. An increase in the saturation temperature to 1050°C during complex chromoalitization using NH4Cl as an activator leads to an increase in the thickness of the resulting coatings to 200-220 microns, with the amount of aluminum on the surface being 16.59% by weight and chromium 4.36% by weight. Keywords: chromium, aluminum, carbon steel, activator, diffusion coatings.

Integrated Assessment of Computational Coronary Physiology From a Single Angiographic View in Patients Undergoing TAVI.

Angiography-derived computational physiology is an appealing alternative to pressure-wire coronary physiology assessment. However, little is known about its reliability in the setting of severe aortic stenosis. This study sought to provide an integrated assessment of epicardial and microvascular coronary circulation by means of single-view angiography-derived physiology in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI). Pre-TAVI angiographic projections of 198 stenotic coronary arteries (123 patients) were analyzed by means of Murray's law-based quantitative flow ratio and angiography microvascular resistance. Wire-based reference measurements were available for comparison: fractional flow reserve (FFR) in all cases, instantaneous wave-free ratio in 148, and index of microvascular resistance in 42 arteries. No difference in terms of the number of ischemia-causing stenoses was detected between FFR ≤0.80 and Murray's law-based quantitative flow ratio ≤0.80 (19.7% versus 19.2%; P=0.899), while this was significantly higher when instantaneous wave-free ratio ≤0.89 (44.6%; P=0.001) was used. The accuracy of Murray's law-based quantitative flow ratio ≤0.80 in predicting pre-TAVI FFR ≤0.80 was significantly higher than the accuracy of instantaneous wave-free ratio ≤0.89 (93.4% versus 77.0%; P=0.001), driven by a higher positive predictive value (86.9% versus 50%). Similar findings were observed when considering post-TAVI FFR ≤0.80 as reference. In 82 cases with post-TAVI angiographic projections, Murray's law-based quantitative flow ratio values remained stable, with a low rate of reclassification of stenosis significance (9.9%), similar to FFR and instantaneous wave-free ratio. Angiography microvascular resistance demonstrated a significant correlation (Rho=0.458; P=0.002) with index of microvascular resistance, showing an area under the curve of 0.887 (95% CI, 0.752-0.964) in predicting index of microvascular resistance ≥25. Angiography-derived physiology provides a valid, reliable, and systematic assessment of the coronary circulation in a complex scenario, such as severe aortic stenosis.

Predictive value of intravascular ultrasound for the function of intermediate coronary lesions

BackgroundIntravascular ultrasound (IVUS) can provide detailed coronary anatomic parameters. The purpose of our study was to evaluate the parameters measured by IVUS for the prediction of intermediate coronary lesions function by referencing quantitative fraction ratio (QFR) ≤ 0.80 (vs. > 0.80).MethodsEighty four cases with 92 intermediate coronary lesions in vessels with a diameter ≥ 2.50 mm were enrolled. Paired assessment of IVUS and cQFR was available, and vessels with cQFR ≤ 0.8 were considered the positive reference standard. Logistic regression was used to select model variables by a maximum partial likelihood estimation test and receiver operating characteristic curve (ROC) analysis to evaluate the diagnostic value of different indices.ResultsPlaque burden (PB) and lesion length (LL) of IVUS were independent risk factors for the function of coronary lesions. The predictive probability P was derived from the combined PB and LL model. The area under the curve (AUC) of PB, (minimum lumen area) MLA, and LL and the predicted probability P are 0.789,0.732,0731, and 0.863, respectively (P < 0.01). The AUC of the predicted probability P was the biggest among them; the prediction accuracy of cQFR ≤ 0.8 was 84.8%, and the sensitivity of the diagnostic model was 0.826, specificity was 0. 725, and P < 0.01.ConclusionPB and LL of IVUS were independent risk factors influencing the function of intermediate coronary lesions. The model combining the PB and LL may predict coronary artery function better than any other single parameter.

The results of laboratory studies on the composition for roofing and waterproofing mastics

The results of laboratory studies on the composition for roofing and waterproofing mastics

Learning from fall-related interventions for older people at home: A scoping review

This scoping review aims to provide a better understanding about the fall-related interventions, and the conditions which stand out as effective in decreasing fall risks of older people at home. A total of 28 peer-reviewed papers were included when they reported interventions with an incidence of falls or fall-risk as a primary outcome for older people, focusing on the home environment, from 8 databases. Qualitative examination was complemented by quantitative risk ratio analysis where it was feasible. The interventions regarding incidence of falls had a mean risk rate of 0.75; moreover, interventions using multiple strategies were found relatively successful. The interventions regarding fall risk had a mean hazard rate of 0.66. A considerable number of no-effect ratios were evident. Combining education, home assessment or improvement, and use of technology with implementation by health service experts appears to be the most promising intervention strategy to reduce falls.

Predictive Value of Post-Percutaneous Coronary Intervention Quantitative Flow Ratio for Vessel-Oriented Composite Endpoint.

At present, there is a lack of indicators, which can accurately predict the post-percutaneous coronary intervention (post-PCI) vessel-oriented composite endpoint (VOCE). Recent studies showed that the post-PCI quantitative flow ratio (QFR) can predict post-PCI VOCE. PubMed, Embase, and Cochrane were searched from inception to March 27, 2022, and the cohort studies about that the post-PCI QFR predicts post-PCI VOCE were screened. Meta-analysis was performed, including 6 studies involving 4518 target vessels. The results of the studies included in this meta-analysis all showed that low post-PCI QFR was an independent risk factor for post-PCI VOCE after adjusting for other factors, HR (95% CI) ranging from 2.718 (1.347-5.486) to 6.53 (2.70-15.8). Our meta-analysis showed that the risk of post-PCI VOCE was significantly higher in the lower post-PCI QFR group than in the higher post-PCI QFR group (HR: 4.14, 95% CI: 3.00-5.70, P < 0.001, I2 = 27.9%). Post-PCI QFR has a good predictive value for post-PCI VOCE. Trial Registration. This trial is registered with CRD42022322001.

Тематические группы русских эвфемизмов об употреблении алкоголя

The aim of the study is to present a thematic classification of euphemisms forming the nominative field ‘alcohol consumption’ taking into account the referent they denote – the aspect of the drinking situation. The paper considers the semantics of euphemistic nominations of alcoholic topics, determines the quantitative ratio of units in different thematic groups, establishes the stylistic nuance of euphemisms. The study is novel in that it is the first to identify, systematise and describe the Russian euphemisms of alcoholic topics presented in the “Dictionary of Euphemisms of the Russian Language” by E. P. Senichkina (2008) by means of semantic, stylistic and quantitative analysis. As a result, it has been proved that euphemisms of the nominative field ‘alcohol consumption’ form eight thematic groups corresponding to the referents of the drinking situation, namely: 1) nominations of the process of alcohol consumption; 2) characteristics of a drinking person; 3) nominations of alcoholic drinks; 4) nominations of alcohol containers; 5) nominations of a place for drinking alcohol; 6) nominations of the state of intoxication; 7) nominations of the amount of the alcohol drunk; 8) nominations of the motives for alcohol consumption.

Drug-eluting stent and drug-coated balloon for the treatment of de novo diffuse coronary artery disease lesions: A retrospective case series study.

The hybrid strategy of a combination of drug-eluting stent (DES) and drug-coated balloon (DCB) is promising for the treatment of de novo diffuse coronary artery disease (CAD). To investigate the efficacy and functional results of hybrid strategy. This case series study included patients treated with a hybrid approach for de novo diffuse CAD between February 2017 and November 2021. Postprocedural quantitative flow ratio (QFR) was used to evaluate the functional results. The primary endpoint was procedural success rate. The secondary endpoints were major adverse cardiovascular events (MACE) including cardiac death, myocardial infarction (MI) (including peri-procedural MI), and target vessel revascularization. A total of 109 patients with 114 lesions were treated. DES and DCB were commonly used in larger proximal segments and smaller distal segments, respectively. The mean QFR value was 0.9 ± 0.1 and 105 patients (96.3%) had values >0.8 in all the treated vessels. Procedural success was achieved in 106 (97.2%) patients. No cases of cardiac death were reported at a median follow-up of 19 months. Spontaneous MI occurred in three (2.8%) patients and target vessel revascularization in six (5.5%) patients. Estimated 2-year rate of MACE excluding peri-procedural MI was higher in the group with lower QFR value (12.1 ± 5.7% vs. 5.6 ± 4.4%, log-rank p = .035) (cut-off value 0.9). Hybrid strategy is a promising approach for the treatment of de novo diffuse CAD. Postprocedural QFR has some implications for prognosis and may be helpful in guiding this approach.

Clinical prognostic value of a novel quantitative flow ratio from a single projection in patients with coronary bifurcation lesions treated with the provisional approach.

A novel quantitative flow ratio (μQFR) for bifurcated coronary vessels, derived from a single projection, has been recently reported. Provisional stenting is effective for most bifurcation lesions. However, the clinical value of the side branch (SB) μQFR in patients with coronary bifurcation lesions undergoing provisional stenting remains unclear. This study aims to determine the clinical predictive value of the SB μQFR after provisional stenting in patients with coronary bifurcation lesions. Between June 2015 and May 2018, 288 patients with true coronary bifurcation lesions who underwent a provisional approach without SB treatment (including predilation, kissing balloon inflation or stenting) were classified by an SB μQFR <0.8 (n=65) and ≥0.8 (n=223) groups. The primary endpoint was the three-year composite of target vessel failure (TVF), including cardiac death, target vessel myocardial infarction (TVMI), and revascularisation (TVR). Three years after the procedures, there were 43 (14.9%) TVFs, with 19 (29.2%) in the SB μQFR <0.8 and 24 (10.8%) in the SB μQFR ≥0.8 groups (adjusted hazard ratio [HR] 2.45, 95% confidence interval [CI] 1.39-5.54; p=0.003), mainly driven by increased TVMI (16.9% vs 5.4%, adjusted HR 3.29, 95% CI: 1.15-6.09; p=0.030) and TVR (15.4% vs 2.2%, adjusted HR 6.39, 95% CI: 2.04-13.48; p=0.007). Baseline diameter stenosis at the ostial SB and SB lesion length were the two predictors of an SB μQFR <0.8 immediately after stenting the main vessel, whereas previous percutaneous coronary intervention and an SB μQFR <0.8 were the two independent factors of 3-year TVF. An SB μQFR <0.8 immediately after the provisional approach is strongly associated with clinical events. Further randomised studies with large patient populations are warranted.

Diagnostic Performance of Intracoronary Optical Coherence Tomography-Modulated Quantitative Flow Ratio for Assessing Coronary Stenosis.

A novel method for fast computation of Murray law-based quantitative flow ratio (μQFR) from coregistered angiography and optical coherence tomography (OCT) was recently developed. This study aimed to evaluate the diagnostic performance of this OCT-modulated μQFR (OCT-μFR). Patients who underwent coronary angiography, OCT, and fractional flow reserve (FFR) were retrospectively enrolled. μQFR was computed from a single angiographic projection. Subsequently, OCT image pullback was coregistered with the angiogram, and OCT-μFR was calculated based on the coregistered data. The same cut-off value of 0.80 was used for OCT-μFR, μQFR, and FFR to define ischemia. A paired comparison of OCT-μFR and μQFR was performed in 269 vessels from 218 patients. The mean FFR was 0.81 ± 0.11, and 45.0% of vessels had an FFR ≤0.80. OCT-μFR showed a better correlation with FFR than μQFR (r = 0.83 vs 0.76, P = .018) and numerically higher diagnostic performance (area under the curve [AUC] = 0.95 vs 0.92, P = .057). Sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio for OCT-μFR to identify ischemia-causing stenosis were 89.3%, 93.2%, 91.5%, 91.4%, 13.2, and 0.1, respectively. In addition, OCT-μFR showed significantly higher diagnostic performance compared with μQFR in vessels with suboptimal angiographic image quality (AUC = 0.93 vs 0.87, P = .028) and tandem lesions (AUC = 0.94 vs 0.87, P = .017). Computation of OCT-μFR was feasible and accurately identified physiologically significant coronary stenosis with simultaneous morphological assessment. In vessels with suboptimal angiographic image quality or tandem lesions, OCT-μFR had a higher diagnostic performance than angiography-based μQFR.

Impact of plaque characteristics on percutaneous coronary intervention-related microvascular dysfunction: insights from angiographic microvascular resistance and intravascular ultrasound.

The correlation between percutaneous coronary intervention (PCI)-related microvascular dysfunction (MVD) and plaque characteristics remains unclear. To investigate this correlation and its prognosis, we assessed changes in MVD by angiographic microvascular resistance (AMR) and intracoronary ultrasound scans after PCI. We conducted a retrospective study that enrolled 250 patients with coronary artery disease between July 2016 and December 2018. We collected demographic characteristics, laboratory tests, coronary angiography (CAG) and intracoronary ultrasound findings. We calculated quantitative flow ratio (QFR) and AMR by CAG. The endpoint was vessel-oriented composite outcomes (VOCOs). After 47 exclusions, we divided 203 cases into a deteriorated group (n=139) and an improved group (n=64) based on AMR change after PCI. Compared with the improved group, the deteriorated group had smaller lumen area [3.03 (interquartile range, 2.20-3.91) vs. 3.55 mm2 (interquartile range, 2.45-4.57), P=0.033], higher plaque burden [78.92% (interquartile range, 73.95-82.61%) vs. 71.93% (interquartile range, 62.70-77.51%), P<0.001], and higher proportion of lipidic components (13.86%±4.67% vs. 11.78%±4.41%, P=0.024). Of 186 patients who completed 4.81±1.55 years follow-up, 56 developed VOCOs. Receiver-operating characteristic (ROC) curve analysis showed post-PCI AMR and VOCOs correlation (area under the curve: 0.729, P<0.001). Multivariate regression analysis showed post-PCI AMR >285 mmHg·s/m correlated with adverse outcome (hazard ratio =4.350; 95% confidence interval: 1.95-9.703; P<0.001). Intravascular ultrasound (IVUS) imaging and AMR revealed an association of post-PCI MVD with a smaller lumen area, more severe plaque burden, and a higher percentage of lipidic components. Post-PCI MVD was an independent risk factor for poor prognosis.

Trophic selectivity of the barnacle goose and the white-fronted goose in the area of reproductive concentration

Against the backdrop of intense transformation of the Arctic environment and biota, differences in population trends of massive and widespread herbivores in the Arctic are of great interest. In this regard, the main goal of our work was a comparative assessment of the trophic selectivity of the barnacle goose and the white-fronted goose under conditions of the largest reproductive concentration, characterizing the role of competition in the dynamics of their populations. It has been shown that the differences in the quantitative ratio of plants eaten by these species are not sufficient to avoid competition, and that the most selective, i.e. The food of the barnacle goose is sensitive to quality and energy-consuming. However, its status as a relatively weak competitor belies the exponential growth of its population in the study area and the entire Arctic population. We believe that differences in the population dynamics of the barnacle goose and the white-fronted goose are currently not due to competition during reproductive concentrations, but to the influence of anthropogenic and climatic factors far beyond the breeding range.