Leadership styles and its relationship with subordinates' self-esteem

Leadership plays an essential role in managing different organizations. These days, different organizations attempt to resolve any existing conflicts through adapting an appropriate leadership strategy. During the past few years, there are increasing interests in examining the relationship between management style and self-esteem. The proposed study of this paper performs an empirical study to find the relationship between leadership style and self-esteem. The proposed study distributed a questionnaire among 80 managers and 150 regular employees of an organization in Iran. We have used Pearson correlation test, t-student and Freedman tests to verify the relationship between leadership style and self-esteem. The investigation of this survey considers four groups of leadership style including autocratic-charity, autocratic-exploitation, management consulting and participative and their effects on self-esteem. The results of our survey indicate that there is a positive and strong relationship between participative leadership management style and self-esteem. The results also indicate that there is strong relationship between educational background and self-esteem

The Effect of Self-Regulation on Improving EFL Readers’ Ability to Make Within-Text Inferences

Self-regulation is the ability to regulate one’s cognition, behavior, actions, and motivation strategically and autonomously in order to achieve self-set goals including the learning of academic skills and knowledge. Accordingly, self-regulated learning involves self-generated and systematic thoughts and behaviors with the aim of attaining learning goals. With that in mind, this study aimed to examine the effect of self-regulation instruction to the intermediate EFL readers on their ability to make within-text inferences while reading. Zimmerman’s model of self-regulation with its three cyclic phases of forethought, performance and self-reflection constituted the theoretical basis of this study. Two intact intermediate classes in an English language institute were randomly assigned to experimental and control groups. The experimental group was trained in self-regulatory processes which were directed at EFL reading comprehension for ten sessions, while the control group received the routine, traditional reading instruction involving pre-, while-, and post-reading tasks and activities. The results of parametric one-way between-group ANCOVA showed that the experimental group outperformed the control group on the post-test of EFL reading comprehension, particularly in term of within-text inferencing. This finding revealed that self-regulation instruction aimed at EFL reading comprehension significantly contributed to learners’ ability to make correct within-text inferences while reading in English as a foreign language

Compatibilization of polycarbonate/poly (ethylene terephthalate) blends by addition of their transesterification product

In this study, poly carbonate (PC) and poly (ethylene terephthalate) (PET) were reactive melt-blended under two different conditions to produce PC/PET copolymers. For each condition, samples were taken at specified mixing times representative a specific structure of copolymers and each one employed to physically compatibilize a PC/PET blend with a fixed composition. Reactive blending and copolymer structure are described by solubility analysis results. Continues declining and going through a minimum are two trends of solubility versus mixing time depending on reactive blending condition. Decreasing and increasing patterns of solubility curves were attributed to the formation of copolymers with longer and shorter block lengths, respectively, and the level of solubility was related to the amount of produced copolymers. Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) techniques were employed to investigate blend compatibility. The content and structure of copolymers showed favorable correlation of Tg differences of blend components and PET crystallinity. As expected, Tg of blend components approached to each other by the addition of copolymers, and the copolymers with longer block length caused less Tg differences. The melting point and crystallinity of PET were affected by introducing the copolymers too. In addition to the main melting endotherm, melting endotherm peaks of compatibilized blends had a shoulder that its corresponding melting point and crystallinity are related to the copolymer structure so that the longer length of block copolymer or higher its amount leads to the higher melting points. The SEM micrographs showed that, after the addition of the copolymer, smaller PET particles formed and uniformly dispersed in the PC matrix. A strong correlation between the blend morphology and the level of blend compatibility was demonstrated. The more compatibilized PC/PET blend, the better dispersion of PET particles in the PC matrix was obtained. The results of this study could be a basis for designing and production of compatibilizers suitable to achieve a desired level of compatibility in PC and polyester blends, specially in PC/PET blend

Rhodopsin kinase and recoverin modulate phosphodiesterase during mouse photoreceptor light adaptation

Light stimulates rhodopsin in a retinal rod to activate the G protein transducin, which binds to phosphodiesterase (PDE), relieving PDE inhibition and decreasing guanosine 3′,5′-cyclic monophosphate (cGMP) concentration. The decrease in cGMP closes outer segment channels, producing the rod electrical response. Prolonged exposure to light decreases sensitivity and accelerates response kinetics in a process known as light adaptation, mediated at least in part by a decrease in outer segment Ca(2+). Recent evidence indicates that one of the mechanisms of adaptation in mammalian rods is down-regulation of PDE. To investigate the effect of light and a possible role of rhodopsin kinase (G protein–coupled receptor kinase 1 [GRK1]) and the GRK1-regulating protein recoverin on PDE modulation, we used transgenic mice with decreased expression of GTPase-accelerating proteins (GAPs) and, consequently, a less rapid decay of the light response. This slowed decay made the effects of genetic manipulation of GRK1 and recoverin easier to observe and interpret. We monitored the decay of the light response and of light-activated PDE by measuring the exponential response decay time (τ(REC)) and the limiting time constant (τ(D)), the latter of which directly reflects light-activated PDE decay under the conditions of our experiments. We found that, in GAP-underexpressing rods, steady background light decreased both τ(REC) and τ(D), and the decrease in τ(D) was nearly linear with the decrease in amplitude of the outer segment current. Background light had little effect on τ(REC) or τ(D) if the gene for recoverin was deleted. Moreover, in GAP-underexpressing rods, increased GRK1 expression or deletion of recoverin produced large and highly significant accelerations of τ(REC) and τ(D). The simplest explanation of our results is that Ca(2+)-dependent regulation of GRK1 by recoverin modulates the decay of light-activated PDE, and that this modulation is responsible for acceleration of response decay and the increase in temporal resolution of rods in background light

Why are rods more sensitive than cones?

One hundred and fifty years ago Max Schultze first proposed the duplex theory of vision, that vertebrate eyes have two types of photoreceptor cells with differing sensitivity: rods for dim light and cones for bright light and colour detection. We now know that this division is fundamental not only to the photoreceptors themselves but to the whole of retinal and visual processing. But why are rods more sensitive, and how did the duplex retina first evolve? Cells resembling cones are very old, first appearing among cnidarians; the emergence of rods was a key step in the evolution of the vertebrate eye. Many transduction proteins have different isoforms in rods and cones, and others are expressed at different levels. Moreover rods and cones have a different anatomy, with only rods containing membranous discs enclosed by the plasma membrane. These differences must be responsible for the difference in absolute sensitivity, but which are essential? Recent research particularly expressing cone proteins in rods or changing the level of expression seem to show that many of the molecular differences in the activation and decay of the response may have each made a small contribution as evolution proceeded stepwise with incremental increases in sensitivity. Rod outer‐segment discs were not essential and developed after single‐photon detection. These experiments collectively provide a new understanding of the two kinds of photoreceptors and help to explain how gene duplication and the formation of rod‐specific proteins produced the duplex retina, which has remained remarkably constant in physiology from amphibians to man. [Image: see text

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Vertebrates acquired dim light vision when an ancestral cone evolved into the rod photoreceptor at an unknown stage preceding the last common ancestor of extant jawed vertebrates (~420 million years ago Ma). The jawless lampreys provide a unique opportunity to constrain the timing of this advance, as their line diverged ~505 Ma and later displayed high morphological stability. We recorded with patch electrodes the inner segment photovoltages and with suction electrodes the outer segment photocurrents of Lampetra fluviatilis retinal photoreceptors. Several key functional features of jawed vertebrate rods are present in their phylogenetically homologous photoreceptors in lamprey: crucially, the efficient amplification of the effect of single photons, measured by multiple parameters, and the flow of rod signals into cones. These results make convergent evolution in the jawless and jawed vertebrate lines unlikely and indicate an early origin of rods, implying strong selective pressure toward dim light vision in Cambrian ecosystems