Size-class structure and growth traits of Anastatica hierochuntica L. populations as rainfall indicators in aridlands

AbstractField data verified by green house experiment were used to evaluate the response of Anastatica hierochuntica L. to the amount of rainfall. Field study of the populations was carried out in the runnel and depression microhabitats of gravel and sand sites. Four water treatments, equivalent to 100, 200, 500 and 1000mm rainfall, were used to simulate different levels of water availability. Under 500 and 1000mm rainfall, the size-class structure of A. hierochuntica populations consists of a high proportion of large size-class individuals, while a higher proportion of small size-class individuals was obtained under 100 and 200mm rainfall. The dry skeletons of A. hierochuntica can be used as a “rain gauge” to predict the amount of rain or water received. The dominance of small size-classes (from <1 to 8cm3) gives a prediction of less than 200mm rainfall received. Intermediate size-classes (8–64cm3) characterize habitats with 200–500mm rainfall, while habitats with >500mm rainfall produce large size-classes (>64cm3). Small size-class individuals produced under low amounts of rainfall allocated up to 60% of their phytomass to the reproductive organs. Allocation to reproductive organs decreased with the increase in the amount of rainfall, while allocation to the stem increased in large size-class individuals produced under the highest amount of rainfall (1000mm) reaching 54%. Increased allocation to stem in large-sized individuals favours the hygrochastic seed dispersal role in the plant. The root/shoot ratio decreased with the increase of the individual size-class, i.e. under high rainfall treatments. Higher values of relative growth rate, net assimilation rate and leaf area index were obtained under high water treatments. Conversely, less expanded leaves, i.e. lower specific leaf area, were manifested in the lowest water treatments

The Effect of Mental Training on Motor Performance of Tennis and Field Hockey Strokes in Novice Players

The aim of this study was to investigate whether the mental training of motor performance can be useful or not in learning tennis and field hockey strokes (forehand, backhand; push pass, hit) Twenty four male tennis-field hockey novice players participated in the study and were divided into experimental group (N = 12) and group for the scientific treatment of the tests (N = 12). Subjects were recruited from Faculty of Physical Education for Men, Alexandria University, Egypt, with ages between 19 to 20 years old. The experimental group attended 16 sessions (8 for tennis, 8 for field hockey) over six weeks (40 minutes each) and used mental training exercises (relaxation, visualization and concentration-attention control) pertinent to the forehand, backhand in tennis and push pass, hit in field hockey. Two waves of measurements were conducted (before and after the completion of the intervention) with the use of motor assessment tests related to the sport of tennis and field hockey. Each student was evaluated regarding to his technique of forehand, backhand in tennis and push pass, hit in field hockey in order to examine the effectiveness of mental training. Questionnaires were also used to measure visualization and concentration-attention control. The results showed a highly significant improvement in learning forehand, backhand in tennis and push pass in field hockey. However, no statistical difference was found for the performance of the hit stroke in field hockey. In addition, the findings showed also a significant difference between the initial and the final measurement regarding to the ability of concentration and visualization by using questionnaires. The results revealed a value of 0.780 which indicates a good reliability of the tool. As a conclusion, a combination of mental and practical training promises the greatest improvement in performance and learning, because it involves all senses

How Viable Is the UTAUT Model in a Non-Western Context?

The present research examines the plausibility of Unified Theory Acceptance and Use Technology (UTAUT) model in predicting internet banking behaviour as a newly adopted technology third world countries. Data is collected from three Arab countries: Jordan, Saudi Arabia and Egypt. Confirmatory factor analysis is applied to test constructs measurement and model hypotheses. Findings are congruent with model testing under conditions of volitional usage behaviour. In this regard, the role of facilitating conditions variable is insignificant as a determinant of usage behaviour. Social norms variable also proved to be weak determinant of behavioural intentions mainly owing to users’ experience. Findings demonstrate effort expectancy as the key determinant of internet banking usage behaviour in the examined markets, while users’ experience moderates the impact of effort expectancy on behavioural intention. Results should enhance our understanding of internet banking usage in developing countries and support e-services promoting in this region

Multi-body dynamics in full-vehicle handling analysis

This paper presents a multidegrees-of-freedom non-linear multibody dynamic model of a vehicle, comprising front and rear suspensions, steering system, road wheels, tyres and vehicle inertia. The model incorporates all sources of compliance, stiffness and damping, all with non-linear characteristics. The vehicle model is created in ADAMS (automatic dynamic analysis of mechanical systems) formulation. The model is used for the purpose of vehicle handling analysis. Simulation runs, in-line with vehicle manoeuvres specified under ISO and British Standards, have been undertaken and reported in the paper

International ownership and firm performance in Arab economies

This paper aims at filling existing research by examining the impact of corporate governance and ownership structure on firm performance using cross-sectional data from companies in the MENA region for the years 2009-2013. The results indicate that higher ownership concentration is associated with higher returns. Furthermore, firms with higher international ownership share tend to perform better than those with only local private and/or state ownership. The results suggest some prevalent features with respect to ownership and performance of firms in the MENA region. Due to the volatile social and business environment, these firms operate in, they may be particularly dependent on effective ownership structures and support which may be provided by international, institutional, and large shareholders

Molecular Role of Nitric Oxide in Secondary Products Production in Ginkgo biloba Cell Suspension Culture

Effects of sodium nitroprusside (SNP; nitric oxide donor) treatment on the enhancement of secondary metabolites production, oxidative stress mediators (O2-.) accumulation and antioxidant defense enzymes of Ginkgo biloba callus culture was investigated. On one hand, the obtained data showed a highly metabolic modification of chemical constituents, PAL activity and various antioxidant defense enzymes (APX, SOD), which gradually increased in response to SNP treatments. On the other hands the high NO levels significantly increased the accumulation of various oxidative burst of O2-.. MS basal medium supplemented with casein hydrolase (500 mg/L), NAA and BA at equal concentration (0.5 mg/L) recorded the highest number of regenerated shoots (4.81 cm) and shoot height (4.96 cm) as well as root number (2.25 cm) and root length (4.5 cm). The highest survival (40 %) was shown in acclimatization on the mixture containing sand, peat moss and vermiculite (1: 1: 1, v/v/v), which significantly confirmed and reflected the variation in survival percentage. Meanwhile, higher treatment (500 &#956;M) of NO positively enhanced secondary products accumulation of total tannins, saponins, phenols and total flavonoids in G. biloba callus culture

Asymmetric hydrogenation of the C-C double bond of 1- and 1,2-methylated maleimides with cultured suspension cells of Marchantia polymorpha

Suspension cultured cells of Marchantia polymorpha have a potentiality to hydrogenate the C-C double bonds of 2-methyl- and 2,3-dimethylmaleimide derivatives to give optically pure (2R)-2-methyl- and (2R,3R)-2,3-dimethylsuccinimide derivatives, respectively

Identification of NeVIII lines in H-deficient (pre-) white dwarfs: a new tool to constrain the temperature of the hottest stars

For the first time, we have identified NeVIII absorption lines in far-UV spectra of the hottest known (Teff>150,000 K) hydrogen-deficient (pre-) white dwarfs of spectral type PG1159. They are of photospheric origin and can be matched by synthetic non-LTE line profiles. We also show that a number of UV and optical emission lines in these stars can be explained as being photospheric NeVIII features and not, as hitherto suspected, as ultrahigh ionised OVIII lines created along shock-zones in the stellar wind. Consequently, we argue that the long-standing identification of the same emission lines in hot [WR]-type central stars as being due to ultrahigh-ionised species (OVII-VIII, CV-VI) must be revised. These lines can be entirely attributed to thermally excited species (NeVII-VIII, NV, OVI). Photospheric NeVIII lines are also identified in the hottest known He-rich white dwarf KPD0005+5106 some of which were also attributed to OVIII previously. This is a surprise because it must be concluded that KPD0005+5106 is much hotter (Teff=200,000 K) than hitherto assumed (Teff=120,000 K). This is confirmed by a re-assessment of the HeII line spectrum. We speculate that the temperature is high enough to explain the mysterious, hard X-ray emission (1 keV) as being of photospheric origin.Comment: Accepted for publication in A&

Consideration of NDVI thematic changes in density analysis and floristic composition of Wadi Yalamlam, Saudi Arabia

Wadi Yalamlam is known as one of the significant wadis in the west of Saudi Arabia. It is a very important water source for the western region of the country. Thus, it supplies the holy places in Mecca and the surrounding areas with drinking water. The floristic composition of Wadi Yalamlam has not been comprehensively studied. For that reason, this work aimed to assess the wadi vegetation cover, life-form presence, chorotype, diversity, and community structure using temporal remote sensing data. Temporal datasets spanning 4 years were acquired from the Landsat 8 sensor in 2013 as an early acquisition and in 2017 as a late acquisition to estimate normalized difference vegetation index (NDVI) changes. The wadi was divided into seven stands. Stands 7, 1, and 3 were the richest with the highest Shannon index values of 2.98, 2.69, and 2.64, respectively. On the other hand, stand 6 has the least plant biodiversity with a Shannon index of 1.8. The study also revealed the presence of 48 different plant species belonging to 24 families. Fabaceae (17&thinsp;%) and Poaceae (13&thinsp;%) were the main families that form most of the vegetation in the study area, while many families were represented by only 2&thinsp;% of the vegetation of the wadi. NDVI analysis showed that the wadi suffers from various types of degradation of the vegetation cover along with the wadi main stream.</p

Structural basis of synthetic agonist activation of the nuclear receptor REV-ERB

The nuclear receptor REV-ERB plays an important role in a range of physiological processes. REV-ERB behaves as a ligand-dependent transcriptional repressor and heme has been identified as a physiological agonist. Our current understanding of how ligands bind to and regulate transcriptional repression by REV-ERB is based on the structure of heme bound to REV-ERB. However, porphyrin (heme) analogues have been avoided as a source of synthetic agonists due to the wide range of heme binding proteins and potential pleotropic effects. How non-porphyrin synthetic agonists bind to and regulate REV-ERB has not yet been defined. Here, we characterize a high affinity synthetic REV-ERB agonist, STL1267, and describe its mechanism of binding to REV-ERB as well as the method by which it recruits transcriptional corepressor both of which are unique and distinct from that of heme-bound REV-ERB