Growth Of Different Parts Research Articles

Linking nitrogen sources utilised by seagrass in a temperate marine embayment to patterns of seagrass change during drought

Reductions in the extent of seagrass Zostera nigricaulis coverage in Port Phillip Bay (PPB), Australia, between 2000 and 2011 coincided with a prolonged period of drought (1997 to 2009) characterized by decreases in freshwater and nutrient inputs. This led us to hypothesize that patterns of seagrass expansion and decline in PPB may be linked to nutrient availability. Seagrasses in PPB can make use of a range of different nitrogen (N) sources depending on their relative availability. Accordingly, there is a need to identify the origin of the N utilised by seagrasses in order to understand how changes in the availability of nutrients from various sources may influence seagrass growth. This study used stable isotope analysis to estimate the contribution of different sources of N to seagrass growth in different parts of PPB. Source modelling indicated that regional patterns of N source utilisation matched changes in seagrass extent from 2000 to 2011. Regions in which seagrass declined contained a similar array of sources, including significant contributions from the catchment area, whereas regions where seagrass areas remained unchanged were largely dependent on a single N source (either fixation/recycled or sewage-derived). We propose that reductions in N from the catchment during the drought may have contributed to the decline of seagrasses in regions where N from the catchment is an important source. This finding is likely to have implications for the growth, distribution and resilience of Z. nigricaulis seagrass in PPB as well as in other parts of its range in southern Australia.

Phytoextraction Efficiency of Lead by Arum (<i>Colocasia esculenta</i> L.) Grown in Hydroponics

Lead (Pb) tolerance and phytoextraction efficiency of arum (Pani Kachu; Colocasia esculenta L.) were investigated in hydroponics. Plants were grown for 60 days in nutrient solution after addition of Pb at the levels of 0, 50, 200 and 400 μM. The growth of different parts of arum was unaffected at low level of Pb concentration (50 μM Pb) compared with control treatment whereas it decreased gradually with the increase of metal concentration in nutrient solution. Concentration of metal in all parts of arum increased significantly with the levels of Pb in the growth media (p < 0.05). In arum shoots, Pb concentration was 1121 mg&#183kg&#451, at its low level in solution. This concentration (50 μM Pb) did not cause any growth retardation which indicated that arum was a Pb hyperaccumulator plant. On an average, translocation of Pb from roots to shoots was 68% of total Pb which indicated that the major portion of Pb was translocated from roots to shoots. Transfer factor (TF) greater than one for this metal as found in the present experiment confirmed the hyperaccumulation characteristics of arum. Lead uptake in the shoots of arum without growth retardation and TF of Pb in arum indicated that this plant was a suitable candidate for the phytoremediation of soil and water contaminated with Pb.

Monitoring of Cell Migration and Apoptosis in Cerebellum of Juvenile Masu Salmon Oncorhynchus Masou After Injury

Apoptosis in various cerebellar zones of juvenile masu salmon Oncorhynchus masou after mechanical injury was investigated by TUNEL-labeling. In the brain of 4 month-old juveniles of O. masou growth in different parts of cerebellum and proliferative activity in secondary matrix zones of cerebellum were continued. TUNEL-labeling was observed in the injured cerebellum 2 days after damage. The induction of proliferative activity in different matrix zones: granular eminences, dorsal part of molecular layer and surface layers of corpus cerebellum were noted. The proliferative activity in regional neurogenic niches is increased after injury of cerebellum. The maximal number of apoptotic elements in the cerebellum was observed in zones of the radial cell migration. We suggest that in damaged cerebellum both adult born cells and cells formed as a result of the reparative neurogenesis can be eliminated during radial migration as result of natural morphogenetic processes. Patterns of tangential and radial migration of cells were observed near the area of injury. The highest rate of apoptosis index was detected in the dorsal matrix zone corresponding to the zone of secondary neurogenesis. This testifies to the elimination of the newly formed cells at the stage of their localization in the matrix zones. The intensity of the apoptotic response varies in different areas of O. masou cerebellum.

Growth and developmental rhythm of Scrophularia ningpoensisin southwest middle mountain area of China

Plant samples were collected and investigated periodically. According to the growth of different parts and the characteristics of dry substance accumulation of Scrophularia ningpoensis, the development of S. ningpoensis could be divided into four stages: seeding stage, stem and leaf growth stage, expanding period of root tubers, and dry substance accumulation stage of root tuber. Leaf numbers of S. ningpoensis grew gradually from one at first to 370 at the final stage, main stem leaf were 50 pieces. Leaf size increasesed with the fastest growth at the stem and leaf growth stage, average daily increase amount was 225 cm2. By the middle of August, leaf size reached to 16,270 cm2. Leaf area indexrose sharply in the seeding stage, and remained above 8 among stem and leaf growth stage and expanding period of root tubers, and rapidly reduced to zero in the stage of dry substance accumulation of root tuber. Leaf area ratio has a tendency of obvious dropping. The net assimilation rate had a small change ranges, two small peak were seeding stage and dry substance accumulation of root tuber. The value of specific leaf area was higher in seeding stage, and in the earlier stage of dry substance accumulation of root tuber. Relative growth rate changed with large ranges, higher in seeding stage, rapid decrease in stem and leaf growth stage, rose in expanding period of root tubers, and declined again in the stage of dry substance accumulation of root tuber. Crop growth rate was higher in the first and last stages, and smaller in interim stage. The growth parameters of S. ningpoensis such as relative growth rate, net assimilation rate, leaf area index, leaf area ratio, specific leaf area, crop growth rate changed along with the growth. The rule of dry matter accumulation was as follows: the dry matter increased slowly during the seeding stage and speeded up in the middle and late stages, and in dry substance accumulation of root tuber increased slower, the growth of dry matter all appeared an "S" curve, and accorded with logistic equation. Cultivation technologies of S. ningpoensis and the relevant management methods could be established according to the growth of different parts of S. ningpoensis and the characteristics of dry substance accumulation in different stage.

Asynchronous responses of East Asian and Indian summer monsoons to mountain uplift shown by regional climate modelling experiments

It has been demonstrated in climate models that both the Indian and East Asian summer monsoons (ISM and EASM) are strengthened by the uplift of the entire Asian orography or Tibetan Plateau (TP) (i.e. bulk mountain uplift). Such an effect is widely perceived as the major mechanism contributing to the evolution of Asian summer monsoons in the Neogene. However, geological evidence suggests more diachronous growth of the Asian orography (i.e. regional mountain uplift) than bulk mountain uplift. This demands a re-evaluation of the relation between mountain uplift and the Asian monsoon in the geological periods. In this study, sensitivity experiments considering the diachronous growth of different parts of the Asian orography are performed using the regional climate model COSMO-CLM to investigate their effects on the Asian summer monsoons. The results show that, different from the bulk mountain uplift, the regional mountain uplift can lead to an asynchronous development of the ISM and EASM. While the ISM is primarily intensified by the thermal insulation (mechanical blocking) effect of the southern TP (Zagros Mountains), the EASM is mainly enhanced by the surface sensible heating of the central, northern and eastern TP. Such elevated surface heating can induce a low-level cyclonic anomaly around the TP that reduces the ISM by suppressing the lower tropospheric monsoon vorticity, but promotes the EASM by strengthening the warm advection from the south of the TP that sustains the monsoon convection. Our findings provide new insights to the evolution of the Asian summer monsoons and their interaction with the tectonic changes in the Neogene.

IMPACT OF INCOME INEQUALITY AND DEFENCE BURDEN ON ECONOMIC GROWTH

This study explores how income inequality and defence burden affects economic growth in different parts of the world. We follow an endogenous growth model that proposes a negative relationship of growth with income inequality and defence burden. The implications of the model are tested using panel data. The results suggest a negative relationship of growth with income inequality and defence burden. A by-product of this analysis is the conclusion regarding convergence. Our study finds no support for convergence across the world.

Heterochrony: the Evolution of Development

Abstract Heterochrony can be defined as change to the timing or rate of development relative to the ancestor. Because organisms generally change in shape as well as increase in size during their development, any variation to the duration of growth or to the rate of growth of different parts of the organism can cause morphological changes in the descendant form. Heterochrony takes the form of both increased and decreased degrees of development, known as “peramorphosis” and “paedomorphosis,” respectively. These are the morphological consequences of the operation of processes that change the duration of the period of an individual’s growth, either starting or stopping it earlier or later than in the ancestor, or by extending or contracting the period of growth. Heterochrony operates both intra- and interspecifically and is the source of much intraspecific variation. It is often also the cause of sexual dimorphism. Selection of a sequence of species with a specific heterochronic trait can produce evolutionary trends in the form of pera- or paedomorphoclines. Many different life history traits arise from the operation of heterochronic processes, and these may sometimes be the targets of selection rather than morphological features themselves. It has been suggested that some significant steps in evolution, such as the evolution of vertebrates, were engendered by heterochrony. Human evolution was fuelled by heterochrony, with some traits, such as a large brain, being peramorphic, whereas others, such as reduced jaw size, are paedomorphic.

Study of cephalometric parameters among 4 to 11 years old Persian girls resident in Iran

Anthropometry is applied in medical profession such as maxillofacial surgery, growth and development studies, plastic surgery, bioengineering and non-medical branches such as like shoe-making and eye-glasses industries. The aim of the present study was to determine facial and cranial parameters among 4 to 11 years old Mashhadian young girls in order to assess growth pattern in this age range. 564 Persian girls aged between 4 to 11 years old resident in Mashhad and had normal facial patterns were selected from schools and kindergartens of the town. At first, frontal photographs in natural head position were taken by an expert person and after scanning all the photographs. They were transmitted to smile analyzer software to measure 13 anthropometric parameters. Pared t-test was used for statistic analysis. Anthropometric results obtained from 4 to 11 years old Fars girls residing in the city of Mashhad show that there is a special discipline in growth of different parts of face and skull. We reached formulas that may have a wide range of applications such as prediction of facial situation of an individual before or after his/her present situation. Such predictions can be helpful in forensic medicine, for instance in finding the lost kids. Reaching a normal range for face dimensions through studies about growth will play an important role in maxillofacial surgery and plastic surgery as well as in study of growth disorders. There are different factors such as ecologic, racial, age, and sex besides all genetic factors that influence the dimensions of human body and the way of its growth and development. Since the Iranian race is a compound one and consists of different races, and there are a wide variety of body dimensions in different parts of Iran, it is necessary to conduct more studies according to the geographical factors and the facial and skull anthropometric data shall be studied in different tribes of Iran. Obtaining an average for each of the variables in Iranian race, the anthropometry studies shall be conducted for different tribes. Key words: Anthropometry, parameters, girls, growth pattern.

Study of some face physical dimensions in Iranian boys

Anthropometry is applied in medical profession, such as maxillofacial surgery, growth and development studies, plastic surgery, bioengineering and non-medical branches such as respiratory equipment and eye-glasses industries. The aim of this study was to determine face physical dimension and cephalo-facial anthropometric ratios in 4 to 11-year-old boys of Iranian Kurmanj population. This cross sectional analytical study was conducted randomly on 564 boys from North Khorasan (bojnourd), with normal face patterns. Cephalo-facial ratios and face physical dimension were estimated and compared. The regression line and the growth coefficient were determined for each parameter. Finally, the mean values of these parameters were determined. Data were analyzed by SPSS software. Paired t-test was used for statistic analysis. Anthropometric results obtained from 4 to 11-year old Kurmanj boys residing in the city of Bojnourd show that there is a special discipline in growth of different parts of the face and skull. We reached formulas (Table 2) that may have a wide range of applications, such as prediction of facial situation of an individual before or after his/her present situation. Such predictions can be helpful in forensic medicine, for instance in finding the lost kids. Reaching a normal range for face dimensions through studies about growth will play an important role in maxillofacial surgery and plastic surgery as well as in the study of growth disorders. Based on our findings in Kurmanj 4 to 11-year boys, we concluded that by age, craniofacial dimensions change at different rates and different craniofacial dimensions do not grow at consistent rates. Some parts grow slower as compared to others. There are different factors, such as ecologic, racial, age and sex besides all genetic factors that influence the human cephalo-facial dimensions and the way of its growth and development. Since the Iranian peoples is a compound one and consists of different races, and there are a wide variety of body dimensions in different parts of Iran, it is necessary to conduct more studies according to the geographical factors and the facial and skull anthropometric data shall be studied in different tribes of Iran. Key words: Anthropometry, cephalic, physical dimensions, face.

Effects of dietary consistency on craniofacial and occlusal development in the rat.

Moderate differences in the hardness of diet are related to significant differences in maxillary width and other measures of facial size. Probably even more important is a relationship to the coordination of growth of different parts of the dentofacial complex. Muscular stimulation mediated through occlusal function seems to play a significant role in the coordinated development of facial structures.

The Implementation of New Accounting Standards of the Economic Consequences of Regional Differences: Analysis from the Perspective of Institutional Economics

Based on the new institutional economics perspective of the research hypothesis is: the same set of accounting standards for different extent economically developed region with a significant difference, the rate of economic growth in different parts of the impact of the company, there are also significant differences. We take advantage of new accounting standards starting in 2007 after the implementation of the first quarter of data, analysis of new accounting standards before and after the changes in the profitability of listed companies. The study found that the implementation of new accounting standards consequences of significant regional differences. The use of annual data robustness testing, empirical conclusions of this study support the hypothesis. In this study, the discovery of accounting standards for the formulation and the effect of pre-judgment, has significance. IFRS for the understanding of the implementation of the worldwide consequences have significance.

Spatial organization of centrosome-attached and free microtubules in 3T3 fibroblasts

Microtubules spatial organization is essential for different cellular processes to proceed normally. It is supposed traditionally, that the fibroblasts have radial microtubule array consisting of long microtubules running from the centrosome. However, the detailed analysis of the microtubule array in the internal cytoplasm has never been performed. In the current study we used laser photobleaching for the analysis of the spatial organization of microtubules in the internal cytoplasm of cultured 3T3 fibroblasts. Cells were injected with Cy-3-labeled tubulin, and then in the bleached zone growth of microtubules in the centrosome region and in the peripheral parts of cytoplasm was analyzed. In most cases microtubules growth in the bleached zone occurred rectilinearly, on the distance up to 5 microm they seldom bend more than 10-15 degrees. We considered a growing fragment of the microtubule as a vector with the beginning in the point of occurrence and with the end in a point where growth terminated (or the end point after 30 s if microtubule's persistent growth proceeded longer). We defined the direction of microtubules growth in different parts of the cell using these vectors and measured the angle of their deviation from the vector of comparison. In the area of the centrosome we directed the vector of comparison inside of the bleached zone from the centrosome to the beginning of the growing microtubule segment; in fibroblast lamella and in fibroblast trailing part we used, the vector of comparison was directed along the long axis of the cell from its geometrical center to periphery. The microtubules growing immediately from the centrosome grew along the cell radius. However at a distance of 10 microm from the centrosome radially growing microtubules gave 40% from the overall number, and at a distance of 20 microm--only 25%. The rest of microtubules grew in different directions, with the preferred angle between their growth direction and cell radius around 90 degrees. Fibroblast lamella and trailing part 80% of all microtubules grew along the cell long axis or at the angle no more than 20 degrees, and 10-15% of microtubules grew along cell axis but towards the centrosome. Thus, in 3T3 fibroblasts the radial system of microtubules is perturbed starting from the distance of several microns from the centrosome. In the internal cytoplasm the microtubule system is completely disordered, and in the stretched parts of the polarized cell (lamella, trailing edge) the microtubule system again becomes well organized--microtubules are preferentially oriented along the long cell axis. From the results obtained we conclude that orderliness of microtubules at the periphery of the fibroblast is not a consequence of their growth from the centrosome, but their orientation is preset by local factors.

General considerations about the use of allometric equations for biomass estimation on the example of Norway spruce in central Europe

Allometric relations for tree growth modelling have been subject to research for decades, partly as empirical models, and partly as process models such as the pipe model, hydraulic architecture, mechanical approaches or the fractal-like nature of plant architecture. Unlike empirical studies, process models aim at explaining the scaling within tree architecture as a function of biological, physical or mechanical factors and at modelling their effect on functionality and growth of different parts of an individual tree. The goal of the underlying study is to link theoretical explanation to empirical approaches of tree biomass estimation by the example of Norway spruce ( Picea abies [L.] Karst.). Decisively, this article tries to take allometry out of the purely curve-fitting exercise common in literature and derives implications for the use of allometric biomass functions. Our results demonstrate that the dbh as independent variable might be misleading for the comparison of universal scaling laws with empirical studies. We were able to show, that the use of a recalculated diameter in relative stem height by means of a taper form model confirms general biological implications better than the dbh measured at a fixed tree height. We used a compiled dataset of altogether 245 trees that were measured on different sites in central Europe to proof our consideration. As one result we estimated a scaling factor b of 2.65 for the allometric relation (agb = a D 0.1 b ) between a diameter in relative stem height ( D 0.1) and aboveground biomass (agb), which is close to scaling relations predicted by process models. The standard error of a linear regression model based on the log-transformed variables could be slightly reduced to 0.21 ( R 2 = 0.98) when we used the diameter in relative tree height.

Emergent Patterning Phenomena in 2D Cellular Automata

This article discusses mechanisms of pattern formation in 2D, self-replicating cellular automata (CAs). In particular, we present mechanisms for structure replication that provide insight into analogous processes in the biological world. After examining self-replicating structures and the way they reproduce, we consider their fractal properties and scale invariance. We explore the space of all possible mutations, showing that despite their apparent differences, many patterns produced by CAs are based on universal models of development and that mutations may lead either to stable or to unstable development dynamics. An example of this process for all possible one-step mutations of one specific CA is given. We have demonstrated that a self-replicating system can carry out many slightly different but related entities, realizing new different growth models. We infer that self-replicating systems exist in an intermediate regime between order and chaos, showing that these models degrade into chaotic configurations, passing through a series of transition stages. This process is quantified by measuring the Hamming distances between the pattern produced by the original self-replicator and those produced by mutated systems. The analysis shows that many different mechanisms may be involved in patterning phenomena. These include changes in the external or internal layers of the structure, substitution of elements, differential rates of growth in different parts of the structure, structural modifications, changes in the original model, the emergence of different structures governed by different CA rules, and changes in the self-replication process.

Patterns of above- and below-ground response of understory conifer release 6 years after partial cutting

An increased pressure to use silvicultural techniques not based on clear-cutting followed by planting has led to an interest in systems that take advantage of existing understory seedlings (advance regeneration). Earlier studies have suggested that following harvesting, understory seedlings may experience growth reductions before responding with growth increases. We hypothesize that this "growth shock" following release results because seedlings are ill adjusted to the new growing conditions and that this can be investigated through a comparison of growth in different parts of the tree over a 6-year period. This study compares the growth response of three size classes of lodgepole pine (Pinus contorta Dougl. ex Loud.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings to a partial overstory removal in relatively dry conifer forests of central British Columbia. Growth was evaluated in four parts of the studied trees: radial increment in roots, in the base of the stem, and in branches, as well as leader height growth extension. Our findings show that following release from the overstory, early growth increases were largest in the roots and stems irrespective of the species or the size class. Differences between the species were observed in greater absolute height growth for pine, whereas Douglas-fir invested in greater stem growth, especially in the larger individuals. Important differences also occurred temporally. Both species (and all size classes) responded with an immediate increase in root growth followed, after a 1-year delay, by an increase in stem growth. Branch radial increment (for pine) and leader height growth (both species), however, experienced 2 to 3 year growth reductions before responding. It is therefore suggested that individuals restore the root–shoot balance by greater initial investments to root growth to offset the increased transpiration losses associated with the greater light and higher temperature conditions and the relative changes in the photosynthetic versus nutrient uptake capacity following the canopy opening. Foresters may therefore be able to manipulate tree growth responses by using an appropriate degree of overstory removal or opening size.

The contributions of craniofacial growth to clinical orthodontics

Balanced facial form and functions are derived from a harmonious integration of the various components of the craniofacial complex. These components grow and develop throughout life in a sequential, predictable, and orderly fashion, albeit with a wide range of variation in the amount and timing of growth. The knowledge of growth-related changes is essential in planning orthodontic treatment. It is important to understand and anticipate the amount and relative rate of growth in different parts of the face, especially during childhood and adolescence. The orthodontist needs to assess the developmental status of the individual and estimate the remaining growth to plan treatment. Incremental growth curves made on linear measurements from longitudinal cephalometric radiographs have demonstrated that all facial dimensions have varying relative rates of growth and show small prepubertal and postpubertal growth spurts. 1 The pubertal spurt in facial dimensions was found to coincide with the spurt in skeletal growth, as reflected by body height, lasting 3 to 4 years. It is apparently of shorter duration and occurs earlier in females than in males. To determine the time of the peak growth period in facial dimensions for an individual, several maturity indicators have been tested. The closest relationship was found with skeletal maturation, which can be readily assessed from hand and wrist radiographs. In many cases orthodontic treatment should commence before the onset or early during the pubertal spurt in order to take advantage of the accelerated growth period. Individual variability in amount and rate of growth is fairly large, related mainly to heredity (familial potential), gender, and ethnic background. In addition, growth is a life-long process. The face of an adult male continues to become progressively more orthognathic. 2 The nose grows downward and forward, while the commissure of the lips moves down with lengthening

Epithelial involution and basement membrane loss during early rhombencephalic tectoria lamina development.

Extracellular material molecules play a key role in the regulation of morphogenesis and differentiation of a large number of organs including the central nervous system. However, the role of the neural basement membrane in the growth of different parts of the neural tube has yet to been delineated. Here, the structural and compositional modifications of the basement membrane (BM) of rhombencephalic tectoria lamina anlage (RTLA) have been examined during the process of RTLA epithelial attenuation. Between stages 10 to 11-the presumptive RTLA epithelium showed a structure, thickness and cell-proliferating capacity similar to those observed in other zones of the rhombencephalic walls. Moreover, the rhombencephalic vesicles were surrounded by a continuous BM that was heterogeneous both ultrastructurally and with regard to ruthenium red, laminin and tenascin distribution. After stage 11, the RTLA epithelium underwent a rapid process of attenuation and change to a stratified flattened epithelium. During this remodelling process, apoptosis and inhibition of both PCNA expression and 3H-thymidine uptake occurred in the RTLA epithelium. The BM of the RTLA underwent a process of degration at the beginning of the remodelling, and apoptosis and cell proliferation inhibition of RTLA epithelium were also observed. The loss of the biochemical signals encoded within the BM could lead to cell shape changes, cell proliferation inhibition and to the anoikis type of cell death. Our findings support the idea that the BM surrounding the neural tube plays a key role in controlling both the structure and growth of the CNS during the early developmental stages.

Mouse Models for the Analysis of Myopia: An Analysis of Variation in Eye Size of Adult Mice

To assess the relative importance of genetic and environmental factors that modulate eye growth, eyes, lenses, and retinas of 507 mice belonging to 50 strains were measured. Mice of both sexes and a wide range of ages (27 to 526 days) were perfused for electron microscopy and eyes, lenses, and retinas were dissected and measured. Our uniform fixation protocol was shown to cause a weight loss of 4 to 6%. Multiple linear regression methods were used to explore relations between eye and lens weight, retinal area, age, sex, body and brain weight, and retinal ganglion cell number. The eye and lens of mice continue to grow long after sexual maturity is reached at 40 to 60 days of age. The pace of growth matches the logarithm of age. Despite their smaller bodies, females have eyes as large as those of males. The correlation of eye weight to brain weight is remarkably low (r = 0.19), whereas that to retinal area is high (r = 0.86). Surprisingly, the correlation between lens weight and the size of the posterior segment (eye minus lens weight) is only 0.5 to 0.6, and ratios of these parameters are highly variable. Heritability of all traits is between 25 to 50%. The continued growth of eyes in adult mice provides an excellent system to test effects of genetic and molecular manipulations on the development and treatment of myopia. Heritability is sufficiently high to map genes that specifically modulate growth of different parts of the eye.

Some factors influencing the increment of forests

It is humbling to read the paper by R.N. Aldrich-Blake (1927) because he deduced many truths that we have since confirmed, and he deduced them with the most subtle of arguments. His article could still be used if one were to start building a computer model to capture the physiological processes of tree growth. His ideas alone would provide a suitable framework for modelling and most of the internal and external factors affecting assimilation and respiration would be included. The model would lack a modern understanding of biochemistry, particularly of photosynthesis and the role of nutrients, and Aldrich-Blake did not consider the important problem of allocating assimilated carbon to the growth of different parts of the tree. Our ideas on allocation are now changing and there is emerging evidence for the role of plant signals in allocation which, in turn, affects the increment in timber volume.

Causal Influences on Productivity Performance 1820-1992: A Global Perspective

This paper has three main purposes: a) it uses a comparative quantitative framework to demonstrate the pace of economic growth in different parts of the world economy since 1820, and to identify the major causes which have been operative; b) it analyses the different approaches which economists have developed to interpret proximate growth causality; and (c) it reviews the role of institutions and other deeper and less measurable influences on growth performance.