Two simulated coenoclines and a real data set were differently recoded with respect to the Braun-Blanquet coding (including presence/absence) and analysed through the most common multidimensional scaling methods. This way, we aim at contributing to the debate concerning the nature of the Braun-Blanquet coding and the consequent multidimensional scaling methods to be used. Procrustes, Pearson, and Spearman correlation matrices were computed to compare the resulting sets of coordinates and synthesized through their Principal Component Analyses (PCA). In general, both Procrustes and Pearson correlations showed high coherence of the obtained results, whereas Spearman correlation values were much lower. This proves that the main sources of variation are similarly identified by most of used methods/transformations, whereas less agreement results on the continuous variations along the detected gradients. The conclusion is that Correspondence Analysis on presence/absence data seems the most appropriate method to use. Indeed, presence/absence data are not affected by species cover estimation error and Simple Correspondence Analysis performs really well with this coding. As alternative, Multiple Correlation Analysis provides interesting information on the species distribution while showing a pattern of relevés very similar to that issued by PCA.
The aspiration of this research paper is to investigate the impact of international gold prices on the equity returns of Karachi Stock Index (KSE100 index) of Pakistan Stock Exchange. The daily observations from January 1, 2000 – June 30, 2016 have been divided into three sub-periods along with the full sample period on the basis of structural breaks. Descriptive analysis used to calculate the average returns, which showed significant returns of KSE100 for the full sample, the first and the third sample periods as compared to gold returns. Standard deviation depicted the higher volatility in all the sample periods. Correlation analysis has shown an inverse relationship amid equity returns and gold returns, whereas, Philips-Perron and Augmented Dickey-Fuller tests have been employed, and time series data became stationary after taking the first difference. Johansen cointegration results have shown that the series are cointegrated in the full-sample and the first sample periods. Thus, this has demonstrated the long run association amid equity returns and gold returns in the first sub-sample and the full-sample periods. However, the second and the third sub-sample periods do not exhibit long-term association amid equity returns of KSE100 and gold returns. The outcomes of Granger causality approach identified bidirectional causation amid equity returns and gold returns in the full sample period in lag 2, and unidirectional causality has been observed from gold prices to stock prices in the full sample and the first sub-sample periods in lag 1 and lag 2 respectively.
Phubbing can be described as an individual looking at his or her mobile phone during a conversation with other individuals, dealing with the mobile phone and escaping from interpersonal communication. In this research, determinants of phubbing behavior were investigated; in addition, the effects of gender, smart phone ownership and social media membership were tested as moderators.
To examine the cause–effect relations among the variables of the theoretical model, the research employs a correlational design. Participants were 409 university students who were selected via random sampling. Phubbing was obtained via the scales featuring mobile phone addiction, SMS addiction, internet addiction, social media addiction and game addiction. The obtained data were analyzed using a correlation analysis, multiple linear regression analysis and structural equation model.
The results showed that the most important determinants of phubbing behavior are mobile phone, SMS, social media and internet addictions.
Although the findings show that the highest correlation value explaining phubbing is a mobile phone addiction, the other correlation values reflect a dependency on the phone.
There is an increasing tendency towards mobile phone use, and this tendency prepares the basis of phubbing.
Authors:István Harta, Miklós Gulyás, and György Füleky
A Gödöllői Agrártudományi Egyetemen 1970-ben 1 hektáros kísérleti területet hoztak létre, ahol 16 éven keresztül vizsgálták különböző műtrágyakezelések (N, P, K) kukorica monokultúrára gyakorolt hatását. Ezt követően összesen 6 t·ha-1 mennyiségű CaCO3-ot juttattak ki a kísérleti terület felére, majd 1995-ben a terület-re fehér akácot telepítettek. A munka során a nagy mennyiségű, komplex műtrágyá-zás hosszú távú hatását vizsgáltuk 20 éve telepített akácállomány szerkezeti para-métereire. Ehhez 48 mintaparcellát jelöltünk ki (4x12 műtrágya-kezelés) úgy, hogy minden kezeléscsoportból egy-egy ismétlés legyen.
A legfontosabb meghatározott paraméterek a törzsszám, a törzstávolság, a lomb-korona-záródás, a cserjeszint-záródás, a körlapösszeg, az átlagos mellmagassági átmérő, az átlagmagasság és a fatérfogat voltak. Ehhez a mintaterületen található 369 db akác mellmagassági átmérőit és 40 mintafa magasságát mértük meg.
A statisztikai elemzés során kéttényezős varianciaanalízist és korreláció-analízist alkalmaztunk.
Az eredmények alapján minden szerkezeti paraméter esetében szignifikáns kü-lönbség volt, a kezelések tehát hatással voltak az akácos szerkezetének alakulására. A lineáris korrelációvizsgálat eredményei szerint a kijuttatott tápanyagok és a me-szezés hatásai komplex formában jelentkeznek. A kijuttatott foszfor- és kálium csak a lombkorona-záródásra mutatott gyenge korrelációt. A kijuttatott nitrogén ható-anyagra sem lehet korrelációt megállapítani. Ennek oka valószínűleg az, hogy a nagy mennyiséget kapott parcellákon csökkent a légköri nitrogénfixáció. A mesze-zés hatására több helyen adódott szignifikáns különbség, tehát a kijuttatott CaCO3 hatással volt az egyes elemek felvehetőségére, így az állomány szerkezeti paraméte-reire. A meszezés hatása leginkább a növőtér nagyságában és a cserjeszint záródá-sában mutatkozik meg. A csökkent növőtér eredményeképp az egyes szerkezeti paraméterek (átlagos mellmagassági átmérő, átlagmagasságok) értékei csökkentek, ez azonban nem okozta a hektáronkénti fatérfogatok alacsonyabb értékét.
A kijuttatott műtrágyaadagok növelték a faállomány térfogatát, a termőhely mi-nősége ellenére jó-közepes fatermési osztályokat lehet megállapítani. A kis parcel-laméretek és az erdők tápanyagforgalmának sajátosságai miatt az állomány egyes paraméterei a kiegyenlítődés irányába mutatnak.
Authors:Bogdan Skwarzec, Krzysztof Kabat, Tomasz Puzyn, and Aleksander Astel
The study deals with the application of cluster analysis (CA) and non-parametric tests (Shapiro–Wilk, Kruskal–Wallis, Dunn,
U Mann–Whitney) to classify and interpret of a monitoring data set for Odra River water quality assessment based on concentration
values of radiochemical parameters. The data set represents results for 3 alpha emitters (210Po, 238U and 239+240Pu) measured in surface water samples collected at 13 different sampling locations (5 in major Odra stream while 8 in Odra
tributaries) within four seasons: winter, spring, summer and autumn, in the framework of 1 year-term quality monitoring research.
The correlation analysis of polonium, uranium and plutonium data indicates that significant values of Spearman’s correlation
coefficient appears between 210Po and 239+240Pu (r = 0.55 in autumn and 0.77 in winter as well as 0.49 in all year), while statistical significant correlation between uranium
and plutonium as well as uranium and polonium were not found. In the Odra drainage basin, the biggest differences were observed
in the case of 238U. The hypothesis about possible geographic and seasonal differences between concentration of 210Po, 238U and 239+240Pu in the Odra River catchment area was verified by cluster analysis (CA). Finally, to asses if there are statistically significant
differences in mean concentration value of 210Po, 238U and 239+240Pu for Vistula and Odra Rivers drainage basins were obtained by used of the non-parametric tests. Comparing to Vistula catchment
area, statistically different concentration of 210Po and 239+240Pu in all year was observed for river samples collected on Odra drainage basin.
The Earth topographic masses are compensated by an isostatic adjustment. According to the isostatic hypothesis a mountain is compensated by mass deficiency beneath it, where the crust is floating on the viscous mantle. For study of the impact of the compensating mass on the topographic mass a crustal thickness (Moho boundary) model is needed. A new gravimetric-isostatic model to estimate the Moho depth, Vening Meinesz-Moritz model, and two well-known Moho models (CRUST2.0 and Airy-Heiskanen) are used in this study. All topographic masses cannot be compensated by simple isostatic assumption then other compensation mechanism should be considered. In fact small topographic masses can be supported by elasticity of the larger masses and deeper Earth’s layers. We discuss this issue applying spatial and spectral analyses in this study. Here we are going to investigate influence of the crustal thickness and its density in compensating the topographic potential. This study shows that the compensating potential is larger than the topographic potential in low-frequencies vs. in high-frequencies which are smaller. The study also illustrates that the Vening Meinesz-Moritz model compensates the topographic potential better than other models, which is more suitable for interpolation of the gravity field in comparison with two other models. In this study, two methods are presented to determine the percentage of the compensation of the topographic potential by the isostatic model. Numerical studies show that about 75% and 57% of the topographic potentials are compensated by the potential beneath it in Iran and Tibet. In addition, correlation analysis shows that there is linear relation between the topographic above the sea level and underlying topographic masses in the lowfrequencies in the crustal models. Our investigation shows that about 580±7.4 metre (in average) of the topographic heights are not compensated by variable the crustal root and density.
To determine the effect of tree canopy composition on understory species abundance, three-hundred 2 m × 2-m quadrats from 30 high-latitude boreal forest stands were sampled. In addition, all trees within a 3mradius of each quadrat center and ≥1 m tall were also measured for height, basal diameter, and canopy width (n = 3130). Stands were 33–178 years old, with canopies of Populus tremuloides (trembling aspen) and Picea spp. (spruce) in varying proportions. Arctostaphylos uva-ursi, Calamagrostis purpurascens, Chamerion angustifolium, Shepherdia canadensis, and Hylocomium splendens were the most frequent understory species among quadrats. Scatterplots of P. tremuloides and individual vascular understory species cover values lacked bivariate trends, but the understory species had distinct maxima that ranged from 20 to 90%. A moderately strong correlation (r = 0.52, P <0.001) occurred between P. tremuloides canopy and total vascular understory plant covers, but weak individual species correlations (r = 0.22–0.35, P <0.001), suggested understory species variation was primarily determined by factors other than the amount of immediately overhead canopy cover. Canonical correlation analysis (R = 0.82, P <0.001) indicated that greater vascular understory plant cover occurred when forest stands consisted of P. tremuloides with large canopies and large basal diameters, and lacked Picea. Maximum cover for vascular understory species declined when Picea cover exceeded 7–10%. In combination, P. tremuloides stem densities or a metric based on summed canopy areas converted to a diameter value (canopy-area diameter), and the vertical silhouette area of Picea canopies (canopy profile area), as independent linear regression variables, explained ∼79% of the variance in total vascular understory plant cover. Several Picea basal areaderived metrics were strongly and positively associated with increasing H. splendens cover, but canopy profile area was more informative. Populus tremuloides canopy area and Picea canopy profile area, as indicators of shading, may be important determinants of vascular understory vegetation abundance in stands where solar radiation enters at angles of up to 52° during the summer.