Preferences and amount of food eaten by the prawn Penaeus esculentus over moult cycle

1992 ◽  
Vol 43 (4) ◽  
pp. 727 ◽  
Author(s):  
BJ Hill ◽  
TJ Wassenberg
Keyword(s):  
Regression Analysis ◽  
Feeding Behaviour ◽  
Carapace Length ◽  
Linear Regression Analysis ◽  
Moult Cycle ◽  
Natural Diet ◽  
Stepwise Linear Regression Analysis ◽  
Stepwise Linear Regression ◽  
Daily Food ◽  
Before And After

Analysis of the natural diet of prawns over the moult cycle shows a preference for molluscan tissue at all stages, with an apparent greater preference in the stage immediately following the moult dropping in the intermoult stages and then increasing again before the next moult. A laboratory study was carried out to provide more information on feeding behaviour over the moult cycle. Adults of Penaeus esculentus (carapace length 25 to 30 mm, weight 15.5 to 25.2 g) held at 32 to 35 and 23 to 25°C did not feed on the night of ecdysis. On the following nights, feeding increased to peak at 2.7 g of penaeid tissue per day in moult Stage C. For the rest of the moult cycle, feeding was fairly steady at about 1.23 g of penaeid tissue per day but dropped sharply two nights before ecdysis. The prawns increased in weight by 0.7 to 6.1 g (mean 3.5 g) over a moult cycle. A stepwise linear-regression analysis showed that, within the range tested, the increase in weight was not a function of prawn weight, duration of moult cycle (range 14 to 34 days), or daily food consumption (0.95 to 2.33 g). They ate more crustacean tissue (Metapenaeus bennettae) than bivalve tissue (Perna canaliculatus) over the entire moult cycle, except for the night before and after ecdysis, when they ate bivalve tissue almost exclusively.

scholarly journals Impact of the COVID-19 pandemic on migraine in Japan: a multicentre cross-sectional study

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Keisuke Suzuki ◽  
Takao Takeshima ◽  
Hisaka Igarashi ◽  
Noboru Imai ◽  
Daisuke Danno ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Regression Analysis ◽  
Linear Regression ◽  
Linear Regression Analysis ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Stepwise Linear Regression Analysis ◽  
Stepwise Linear Regression ◽  
New Onset

Abstract Objectives To assess the impacts of social situation changes due to the coronavirus disease 2019 (COVID-19) pandemic on headache-related disability and other symptoms in patients with migraine in Japan. Methods We conducted a multicentre, cross-sectional study including 659 outpatients with migraine diagnosed by headache specialists. The participants were asked about the impacts of the first wave of the COVID-19 pandemic on headache-related disability, headache days, headache intensity, stress, physical activity, hospital access and their work and home lives. For headache-related disability, the total Migraine Disability Assessment (MIDAS) score and part A and B scores were analysed. Multivariate stepwise linear regression analysis was performed to identify the clinical predictors of changes in the total MIDAS score before and during the COVID-19 pandemic. Logistic regression analysis was performed to determine the factors related to new-onset headache during the COVID-19 pandemic. Results Finally, 606 migraine patients (73 M/533 F; age, 45.2 ± 12.0 years) were included in the study, excluding those with incomplete data. Increased stress, substantial concern about COVID-19 and negative impacts of the first wave of the COVID-19 pandemic on daily life were reported in 56.8 %, 55.1 and 45.0 % of the participants, respectively. The total MIDAS and A and B scores did not significantly change after the first wave of the COVID-19 pandemic. New-onset headache, which was observed in 95 patients (15.7 %), was associated with younger age and worsened mood and sleep in the logistic regression analysis. The multivariate stepwise linear regression analysis of changes in the total MIDAS score before and during the first wave of COVID-19 pandemic identified worsened sleep, increased acute medication use, increased stress, medication shortages, comorbidities, the absence of an aura and new-onset headache were determinants of an increased total MIDAS score during the first wave of the COVID-19 pandemic. Conclusions In this multicentre study, clinical factors relevant to headache-related disability, such as new-onset headache, stress and sleep disturbances, were identified, highlighting the importance of symptom management in migraine patients during the first wave of the COVID-19 pandemic.

scholarly journals FACTORS THAT INFLUENCE LIFE SATISFACTION IN AL RESIDENTS

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S236-S236
Author(s):  
Sarah Holmes
Keyword(s):  
Life Satisfaction ◽  
Regression Analysis ◽  
Physical Environment ◽  
Linear Regression Analysis ◽  
Ongoing Research ◽  
Stepwise Linear Regression Analysis ◽  
Stepwise Linear Regression ◽  
The Mean ◽  
The Impact ◽  
Multidimensional Concept

Abstract Life satisfaction is a multidimensional concept that addresses a personal judgment of quality from the resident’s perspective. Components of life satisfaction include satisfaction related to health, the physical environment, relationships and activities. The purpose of this study was to test if there was a relationship between demographic factors, pain, falls, and use of psychotropics with life satisfaction. The sample included the first two cohorts from the FFC-AL-EIT study including 508 residents from 54 settings across Maryland, Pennsylvania, and Massachusetts. The majority of the participants were female (70%), white (97%) and the mean age was 87.72 (SD=7.47) . Based on a stepwise linear regression analysis there was a significant association between pain (r=-.20, p=.003) and psychotropic use (r=-.19, p=.003) and the model explained 11% of the variance in life satisfaction. Ongoing research is needed to consider the impact of the environment and staff-resident interactions on life satisfaction.

Negative Correlation of Serum Adiponectin Levels With Carotid–Femoral Pulse Wave Velocity in Patients Treated With Hemodialysis

2018 ◽  
Vol 20 (4) ◽  
pp. 462-468 ◽  
Author(s):  
Jia-Sian Hou ◽  
Chih-Hsien Wang ◽  
Yu-Hsien Lai ◽  
Yu-Li Lin ◽  
Chiu-Huang Kuo ◽  
...  
Keyword(s):  
Body Weight ◽  
Regression Analysis ◽  
Waist Circumference ◽  
Pulse Wave ◽  
Adiponectin Level ◽  
Linear Regression Analysis ◽  
Serum Adiponectin ◽  
Stepwise Linear Regression Analysis ◽  
Stepwise Linear Regression ◽  
Forward Stepwise

Purpose: The aim of this study was to evaluate the relationship between serum adiponectin levels and carotid–femoral pulse wave velocity (cfPWV) in hemodialysis (HD) patients. Method: Blood samples were obtained from 120 HD patients. cfPWV was measured with a validated tonometry system (SphygmoCor; AtCor Medical, West Ryde, Australia). Serum adiponectin levels were measured using a commercially available enzyme-linked immunosorbent assay kit. Results: By univariate linear analysis of cfPWV in HD patients, we found that diabetes ( r = .281, p = .002), pre-HD body weight ( r = .194, p = .033), post-HD body weight ( r = .192, p = .036), waist circumference ( r =.210, p = .022), and body fat mass ( r = .194, p = .034) were positively correlated, whereas adiponectin level ( r = −.254, p = .005) was negatively correlated with cfPWV in HD patients. Multivariate forward stepwise linear regression analysis showed that diabetes (β = .274, p = .006) and adiponectin level (β = −.215, p = .016) were independent predictors of cfPWV in HD patients. Moreover, post-HD body weight (β = −.274, p = .041), waist circumference (β = −.311, p < .001), logarithmically transformed triglyceride level (log-TG; β = −.186, p = .031), and log-glucose (β = −.225, p = .008) were negatively associated with adiponectin levels in HD patients after multivariable forward stepwise linear regression analysis. Conclusions: Among HD patients, serum adiponectin level was inversely associated with cfPWV level, and post-HD body weight, waist circumference, log-TG, and log-glucose were negatively associated with adiponectin level.

scholarly journals A Prediction Equation to Assess Resting Energy Expenditure in Japanese Patients with COPD

2020 ◽  
Vol 9 (11) ◽  
pp. 3455
Author(s):  
Keisuke Morikawa ◽  
Kazuyuki Tabira ◽  
Hiroyuki Takemura ◽  
Shogo Inaba ◽  
Haruka Kusuki ◽  
...  
Keyword(s):  
Body Weight ◽  
Regression Analysis ◽  
Energy Expenditure ◽  
Linear Regression Analysis ◽  
Resting Energy Expenditure ◽  
Fat Free Mass ◽  
Stepwise Linear Regression Analysis ◽  
Stepwise Linear Regression ◽  
Copd Patients ◽  
Resting Energy

Background: Medical nutrition therapy is important in the management of chronic obstructive pulmonary disease (COPD) patients. Determination of resting energy expenditure is essential to define therapeutic goals for medical nutrition. Previous studies proposed the use of equations to predict resting energy expenditure. No prediction equation is currently available for the Japanese population. The objective of this study was to develop an equation to predict resting energy expenditure in Japanese chronic obstructive pulmonary disease patients. To this end, we investigated clinical variables that correlate with the resting energy expenditure. Methods: This study included 102 COPD patients admitted at the Matsusaka Municipal Hospital Respiratory Center. We measured resting energy expenditure by indirect calorimetry and explored the relationship of resting energy expenditure with clinical variables by univariate and stepwise linear regression analysis. Results: The resting energy expenditure by indirect calorimetry was significantly correlated with fat-free mass, body weight, body mass index, height, gender, and pulmonary function test by univariate analysis. In the stepwise linear regression analysis, the fat-free mass, body weight, and age remained significantly correlated with indirect calorimetry’s resting energy expenditure. The fat-free mass, body weight, and age explained 50.5% of the resting energy expenditure variation. Conclusion: Fat-free mass, body weight, and age were significantly correlated with resting energy expenditure by stepwise linear regression analysis, and they were used to define a predictive equation for Japanese COPD patients.

scholarly journals Μεταβολές των συστατικών του ελαιολάδου κατά την αποθήκευση και το μαγείρεμα

2015 ◽  
Author(s):  
Καλή Κώτσιου
Keyword(s):  
Regression Analysis ◽  
Linear Regression ◽  
Linear Regression Analysis ◽  
Stepwise Linear Regression Analysis ◽  
Stepwise Linear Regression

Στην παρούσα έρευνα μελετήθηκαν οι μεταβολές στη φαινολική σύσταση παρθένων ελαιολάδων κατά την εφαρμογή οικιακών θερμικών επεξεργασιών. Επίσης, συγκεντρώθηκαν τα αποτελέσματα που αποκτήθηκαν κατά την αποθήκευση παρθένων ελαιολάδων, δίνοντας έμφαση στις πτητικές και φαινολικές ενώσεις καθώς και στα οργανοληπτικά χαρακτηριστικά.Παρθένα ελαιόλαδα υποβλήθηκαν σε θέρμανση υπό συνθήκες που προσομοίωναν οικιακές θερμικές επεξεργασίες, όπως το τηγάνισμα και ο βρασμός. Αυτές οι επεξεργασίες είναι δυνατό να επηρεάσουν το περιεχόμενο σε φαινολικές ενώσεις σε έναν ορισμένο βαθμό. Η θερμική οξείδωση των ελαίων στους 180 °C (τηγάνισμα) προκάλεσε μια σημαντική μείωση (p<0,05) στα παράγωγα της υδροξυτυροσόλης (60% μετά από 30 λεπτά και 90% μετά από 60 λεπτά), ενώ είχε μικρότερη επίδραση στα παράγωγα της τυροσόλης και στις λιγνάνες. Όσον αφορά τη θερμική οξείδωση των ελαίων στους 100 °C (βρασμός) για 2 ώρες, παρατηρήθηκαν μειώσεις μικρότερες από 20% σε όλες τις κατηγορίες των φαινολικών ενώσεων. Κατά την εφαρμογή αυτών των επεξεργασιών, παρατηρήθηκε η δημιουργία οξειδωμένων φαινολικών ενώσεων, οι οποίες χαρακτηρίστηκαν με HPLC-MS.Επιπλέον, δείγματα παρθένου ελαιολάδου πέντε ελληνικών ποικιλιών ελιάς μεταφέρθηκαν σε γυάλινα μπουκάλια (με κενό 0,5%), σφραγίστηκαν και αποθηκεύτηκαν σε σκοτεινό υπόγειο χώρο χωρίς κεντρική θέρμανση. Μετά από 24 μήνες αποθήκευσης, τα βασικά ποιοτικά χαρακτηριστικά των δειγμάτων, όπως η ελεύθερη οξύτητα, οι ειδικοί συντελεστές απόσβεσης (Κ232 και Κ270) και ο αριθμός υπεροξειδίων, δεν ξεπέρασαν τα ανώτατα όρια που καθορίζονται από τον Κανονισμό 2568/91 της Ευρωπαϊκής Ένωσης για το παρθένο ελαιόλαδο.Οι μεταβολές στη σύσταση του πτητικού κλάσματος των παρθένων ελαιολάδων κατά την αποθήκευση, μελετήθηκαν για 18 μήνες. Όσον αφορά τα προϊόντα της οδού της λιποξυγενάσης, τα οποία είναι υπεύθυνα για τις θετικές οργανοληπτικές ιδιότητες, το σύνολό τους παρέμεινε σταθερό κατά τη διάρκεια της περιόδου αποθήκευσης, ωστόσο παρατηρήθηκαν υψηλά ποσοστά σχηματισμού πτητικών προϊόντων οξείδωσης, τα οποία είναι υπεύθυνα για τα οργανοληπτικά ελαττώματα. Μεταξύ των πτητικών προϊόντων οξείδωσης, τα υψηλότερα ποσοστά σχηματισμού καταγράφηκαν για την επτανάλη, την (Ε)-2-επτενάλη και την πεντανάλη ενώ ακολουθούσαν η εξανάλη και η εννεανάλη. Ο ρυθμός σχηματισμού πτητικών προϊόντων οξείδωσης ήταν υψηλότερος στα ελαιόλαδα των ποικιλιών Λιανολιά και Ασπρολιά σε σχέση με αυτά των ποικιλιών Κορωνέικη, Ντόπια Ζακύνθου και Θιακή. Τέλος, με χρήση σταδιακής ανάλυσης γραμμικής παλινδρόμησης (Stepwise Linear Regression Analysis-SLRA) βρέθηκε ότι το λινελαϊκό οξύ και η αναλογία ολικών φαινόλικών/ορθο-διφαινολών έχουν τη μεγαλύτερη συσχέτιση με το ρυθμό σχηματισμού της (Ε)-2-επτενάλης.Οι μεταβολές στη σύσταση του φαινολικού κλάσματος παρακολουθήθηκαν με τη χρήση υγρής χρωματογραφίας υψηλής απόδοσης (HPLC) για 24 μήνες. Οι διαφορές που παρατηρήθηκαν μεταξύ των δειγμάτων στην αρχική συγκέντρωση των φαινολικών ενώσεων (η οποία κυμάνθηκε μεταξύ 250-930 mg/kg) επιβεβαίωσαν την επίδραση του συστήματος εξαγωγής, της ποικιλία της ελιάς και του σταδίου ωρίμανσης του καρπού. Τα παρθένα ελαιόλαδα βρέθηκε να περιέχουν υψηλότερη συγκέντρωση σε φαινολικές ενώσεις, όταν η παραλαβή τους έγινε σε φυγοκεντρικά συστήματα δύο φάσεων σε σχέση με τα τριφασικά. Κάτω από τις επιλεγμένες συνθήκες αποθήκευσης, ακόμη και μετά από 24 μήνες, το ποσοστό της συνολικής μείωσης των φαινολικών ενώσεων δεν υπερέβη το 31%. Η μείωση ήταν μεγαλύτερη στη διαλδεϋδική μορφή της αγλυκόνης της ελαιοευρωπαΐνης (DAFOA) και στη διαλδεϋδική μορφή της αγλυκόνης του λιγκστροζίτη (DAFLA), αποδεικνύοντας μια πιο ενεργή συμμετοχή των πολικών σεκοϊριδοειδών στις διαδικασίες υδρόλυσης ή/και οξείδωσης. Η αρχική συγκέντρωση των δειγμάτων σε φαινολικές ενώσεις ήταν ο κύριος παράγοντας που συσχετίστηκε με το ρυθμό αποδόμησης των ενώσεων αυτών, ενώ η αρχική οξειδωτική κατάσταση και η ελεύθερη οξύτητα συσχετίστηκαν σε πολύ μικρότερο βαθμό. Η μείωση των παραγώγων των σεκοϊριδοειδών, οδήγησε στην αύξηση των απλών φαινολών (υδροξυτυροσόλη και τυροσόλη) και στο σχηματισμό τεσσάρων οξειδωμένων προϊόντων. Τέλος, το πείραμα επαναλήφθηκε, κάτω από τις ίδιες συνθήκες αποθήκευσης, σε ελαιόλαδα από δύο ελληνικές ποικιλίες με σκοπό να εκτιμηθούν οι μεταβολές στα οργανοληπτικά χαρακτηριστικά κατά τη διάρκεια 18 μηνών, που αντιστοιχεί συνήθως στο μέγιστο διάστημα του χρόνου ζωής ενός ελαιολάδου από την εμφιάλωση ως την κατανάλωση. Τα δείγματα που επιλέχθηκαν για αποθήκευση ανήκαν στη κατηγορία του εξαιρετικού παρθένου ελαιολάδου. Όπως φάνηκε από την οργανοληπτική αξιολόγηση, μέρος των δειγμάτων εμφάνισε οργανοληπτικό ελάττωμα με αποτέλεσμα μέχρι το τέλος της αποθήκευσης, να μη πληρούν όλα τα δείγματα τις προϋποθέσεις ώστε να ανήκουν στην κατηγορία του εξαιρετικού παρθένου ελαιολάδου. Τα ελαιόλαδα της ποικιλίας Λιανολιά έδειξαν μία μεγαλύτερη τάση για αλλοίωση σε σχέση με αυτά της Κορωνέικης. Συγκεκριμένα, στους 12 μήνες αποθήκευσης 1 από τα 6 δείγματα Λιανολιάς παρουσίασε ελάττωμα σε αντίθεση με τα δείγματα της Κορωνέικης στα οποία δεν έγινε αντιληπτό κάποιο ελάττωμα κατά το ίδιο χρονικό διάστημα. Στους 18 μήνες αποθήκευσης 2 από τα 6 δείγματα της Λιανολιάς και 1 από τα 6 δείγματα της Κορωνέικης είχαν μεταβεί στη κατηγορία του παρθένου ελαιολάδου. Η ανάλυση κύριων συνιστωσών (PCA) έδειξε ότι τα δείγματα ελαιολάδου μπορούν να διαχωριστούν στις κατηγορίες του εξαιρετικού παρθένου και παρθένου με βάση το προφίλ τους σε αρωματικές ενώσεις. Συγκεκριμένα εντοπίστηκαν δύο κύριες συνιστώσες, που εξηγούν το 74,5% της διακύμανσης, και οι οποίες έδειξαν υψηλό βαθμό συσχέτισης με τα εκατοστιαία ποσοστά του συνόλου των ακόρεστων και κορεσμένων αλδεϋδών με C7-C10, με την ολική συγκέντρωση των προϊόντων της οδού της λιποξυγενάσης, με το εκατοστιαίο ποσοστό των κορεσμένων αλκοολών με C7-C9 καθώς και με την αναλογία εννεανάλη/εξανάλη.

Analysis of variations in and correlations between selected physical parameters of common beech (Fagus silvatica L.) nuts

2017 ◽  
Vol 1 (21) ◽  
pp. 49-63
Author(s):  
Zdzisław Kaliniewicz ◽  
Piotr Markowski ◽  
Andrzej Anders ◽  
Paweł Tylek ◽  
Zbigniew Krzysiak ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Correlation Analysis ◽  
Cross Sections ◽  
Linear Regression Analysis ◽  
Physical Parameters ◽  
Common Beech ◽  
Mesh Screen ◽  
Before And After ◽  
Fagus Silvatica ◽  
Highly Correlated

The basic dimensions and the mass of common beech nuts and seeds from five nut batches, harvested from tree stands in northern Poland, were determined. Environmental conditions had a greater influence on seed plumpness than the age of tree stands. The results of measurements were analyzed statistically by analysis of variance, correlation analysis and linear regression analysis. Despite differences in their plumpness, nuts were characterized by nearly identical cross-sections which resembled an equilateral triangle. The thickness of nuts and seeds was highly correlated with their mass, and this information can facilitate seed husking and separation into mass categories. Before and after husking, seeds should be separated with the use of a mesh screen with longitudinal openings. Medium-sized (most numerous) seeds were separated into the following plumpness categories using a screen separator with ≠6 mm and ≠7 mm openings: 84% of moderately plump seeds, 3% of seeds with reduced plumpness, and 13% of plump seeds.

scholarly journals Psychosocial Factors Associated with Quality of Life in Young Men Who Have Sex with Men Living with HIV/AIDS in Zhejiang, China

2019 ◽  
Vol 16 (15) ◽  
pp. 2667 ◽  
Author(s):  
Tingting Jiang ◽  
Xin Zhou ◽  
Hui Wang ◽  
Mingyu Luo ◽  
Xiaohong Pan ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Social Support ◽  
Self Efficacy ◽  
Linear Regression Analysis ◽  
Monthly Income ◽  
Stepwise Linear Regression Analysis ◽  
Stepwise Linear Regression ◽  
Factors Associated ◽  
Sex With Men

Objectives: To explore the quality of life (QOL) status and related factors in young human immunodeficiency virus (HIV)-infected men who have sex with men (MSM) aged 16 to 24 years in Zhejiang province. Methods: A cross-sectional study was conducted in 22 counties of Zhejiang province, and 395 subjects took part in our research. A t-test, one-way Analysis of variance (ANOVA), and multivariate stepwise linear regression analysis were used to investigate the factors associated with QOL in young HIV-infected MSM. Results: The total score on the QOL was 86.86 ± 14.01. The multivariate stepwise linear regression analysis revealed that self-efficacy and discrimination were associated with all domains on the QOL assessment, monthly income was associated with QOL for all domains except spirituality and consistent condom use during oral sex with men in the past three months was associated with QOL for all domains except the relationship domain. Those individuals within the group of young HIV-infected MSM who have higher self-efficacy, a higher monthly income, greater social support, safer sexual behaviors, a higher level of education, and a higher cluster of differentiation 4 (CD4) count have a better QOL. Conclusions: These findings suggest that to improve the QOL of this population, greater emphasis should be placed on improving social support, self-efficacy, and antiviral therapy adherence and on reducing discrimination, disease progression, and high-risk behaviors.

Anxiety and the Influences of Flow, Trauma, and Fantasy Experiences on Dancers

2012 ◽  
Vol 32 (2) ◽  
pp. 165-178 ◽  
Author(s):  
Paula Thomson ◽  
S. Victoria Jaque
Keyword(s):  
Linear Regression Analysis ◽  
Traumatic Events ◽  
Psychological Effects ◽  
Traumatic Experiences ◽  
Global Flow ◽  
Fantasy Proneness ◽  
Stepwise Linear Regression Analysis ◽  
Stepwise Linear Regression ◽  
Predictive Role ◽  
Flow Experiences

This study investigated the psychological effects of anxiety on professional and pre-professional dancers ( n = 73), in particular the relationships between anxiety and flow, past traumatic events, and fantasy. Results demonstrated that anxiety was statistically related to increased age, total traumatic events, increased fantasy proneness, with no association to flow. All dancers experienced moderate-to-high global flow experiences, and 75.3% of the dancers endorsed high autotelic experiences (an ability to regularly transform potential threats into positive flow experiences). In a stepwise linear regression analysis, together past traumatic events and fantasy explained 19.4% of the variance for anxiety. Greater mean scores for total traumatic events and lower autotelic flow experiences were found in the dancers with pathological levels of anxiety. Since 23.3% of the dancers endorsed clinical levels of anxiety (panic), further understanding regarding panic and anxiety in a dancer population is recommended, specifically the predictive role fantasy proneness and past traumatic experiences may play in anxiety symptomatology.

Impact of Chinese Yuan Devaluation on the Dependence Structure: The Archimedean Copula Approach

2019 ◽  
Vol 22 (01) ◽  
pp. 1950005
Author(s):  
Wing-Choong Lai ◽  
Kim-Leng Goh
Keyword(s):  
Regression Analysis ◽  
Linear Regression ◽  
Extreme Event ◽  
Linear Regression Analysis ◽  
Tail Dependence ◽  
Dependence Structure ◽  
Before And After ◽  
Copula Approach ◽  
Upper Tail Dependence ◽  
Chinese Yuan

This paper investigates the linkages of Chinese yuan to other currencies before and after the yuan devaluation on 11 August 2015. Linear regression analysis shows that only a few of the 14 currencies considered are significantly affected by the devaluation. However, the devaluation of Chinese yuan has been associated with larger fluctuations in these currencies and the occurrence of extreme positive and negative returns. The regression method may under estimate the tail dependence between currencies, as financial data are usually non-normally distributed, especially when extreme event occurs. We apply the Archimedean copulas to capture the presence of lower and upper tail dependence between the exchange rate returns of Chinese yuan and the selected currencies, and found dependencies not revealed by the linear regression analysis. The extreme returns after the Chinese yuan devaluation have resulted in higher dependence with the selected currencies. While the dependence structure was dominated by risks due to unusual currency gains before the devaluation, the market responses to large losses and gains have become more symmetric after the devaluation.

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