Patterns For Growth Research Articles

CELL GROWTH IN VITRO DIRECTED BY HANDMADE PATTERNS

In this report, we show how the in vitro model of mechanically injured confluent monolayers of cultured mammalian cells, consisting in denudation by gentle scraping of areas in the monolayer, can be extended to obtain patterned cell cultures without using preadded attaching matrices. This work was done with a sinusoidal endothelial liver cell line. Patterns for cell growth were drawn in confluent monolayers by cell detaching with the aid of pipette tips followed by reincubation of the culture. In one or some d, acellular patterns were closed by cell migration and proliferation. For unveiling the pattern formed by migration and cell duplication, an enzymatic digestion with trypsin-collagenase solution was applied; after some min, only the migrating and younger cells filling the previous acellular pattern remained attached to the dish, and the now cellular pattern was clearly depicted. After stopping and recovering from the enzymatic treatment, the culture was ready for starting studies such as those related to migration, proliferation, cell-cell interactions. This method allows us to create simple and complex patterns, does not require preparation of the dishes with attaching matrices, and extracellular matrices in acellular areas are absent because of the enzymatic treatment, thus, potentially having many applications in cell culture techniques.

An Optimal Governance Model of Land Use in Watershed: The Case of the Paldang Reservoir

This study focuses on the Paldang reservoir in Korea to introduce an optimal governance model of land use in the watershed from a property rights perspective,. The particular model is developed based on the premise that land use activities, which differ in attributes, can properly be aligned with governance mechanisms in such a way that minimizes the governance costs. Given the intrinsic limitations of the measurement of governance costs, this study applies the discrete structural analysis for the alignment. The model developed in such a manner prescribes very diverse and specific mechanisms for the governance of land use activities, and as such, the relevance of this model to the real world situation is much greater. The diversification of policy measures can not only contribute to the improvement of the water quality in the reservoir, but also provide the watershed residents with the opportunity to develop a series of environmentally sensitive and economically viable patterns for growth and diversity.

Reaction and Diffusion on Growing Domains: Scenarios for Robust Pattern Formation

We investigate the sequence of patterns generated by a reaction–diffusion system on a growing domain. We derive a general evolution equation to incorporate domain growth in reaction–diffusion models and consider the case of slow and isotropic domain growth in one spatial dimension. We use a self-similarity argument to predict a frequency-doubling sequence of patterns for exponential domain growth and we find numerically that frequency-doubling is realized for a finite range of exponential growth rate. We consider pattern formation under different forms for the growth and show that in one dimension domain growth may be a mechanism for increased robustness of pattern formation.

Folding a protein by discretizing its backbone torsional dynamics.

The aim of this work is to provide a coarse codification of local conformational constraints associated with each folding motif of a peptide chain in order to obtain a rough solution to the protein folding problem. This is accomplished by implementing a discretized version of the soft-mode dynamics on a personal computer (PC). Our algorithm mimics a parallel process as it evaluates concurrent folding possibilities by pattern recognition. It may be implemented in a PC as a sequence of perturbation-translation-renormalization (p-t-r) cycles performed on a matrix of local topological constraints (LTM). This requires suitable representational tools and a periodic quenching of the dynamics required for renormalization. We introduce a description of the peptide chain based on a local discrete variable the values of which label the basins of attraction of the Ramachandran map for each residue. Thus, the local variable indicates the basin in which the torsional coordinates of each residue lie at a given time. In addition, a coding of local topological constraints associated with each secondary and tertiary structural motif is introduced. Our treatment enables us to adopt a computation time step of 81 ps, a value far larger than hydrodynamic drag time scales. Folding pathways are resolved as transitions between patterns of locally encoded structural signals that change within the 10 micros-100 ms time scale range. These coarse folding pathways are generated by the periodic search for structural patterns in the time-evolving LTM. Each pattern is recorded as a contact matrix, an operation subject to a renormalization feedback loop. The validity of our approach is tested vis-a-vis experimentally-probed folding pathways eventually generating tertiary interactions in proteins which recover their active structure under in vitro renaturation conditions. As an illustration, we focus on determining significant folding intermediates and late kinetic bottlenecks that occur within the first 10 ms of the bovine pancreatic trypsin inhibitor renaturation process. The probed cooperativity and nucleation effects, as well as diffusion-collision stabilization of secondary structure are shown to result from the persistence of relatively stable patterns through successive (p-t-r) cycles, thus acting as seeding patterns for further growth or hierarchical development.

Fractals for multicyclic synthesis conditions of biopolymers examples of oligonucleotide synthesis measured by high-performance capillary electrophoresis and ion-exchange high-performance liquid chromatography

We have developed models of patterns for nucleotide chain growth. These patterns are measurable by high-performance capillary electrophoresis and ion-exchange high-performance liquid chromatography in crude products of solid-phase synthesized 30mer and 65mer oligodeoxyribonucleotide target sequences N. We introduce mathematical methods for finding characteristic values d 0 and p 0 for constant chemical modes of growth as well as d and p for non-constant chemical modes of growth ( d = probability of propagation, p = probability of termination. These methods are employed by presenting the accompanying computer software developed by us in C code, Mathematica R languages, and Fortran. Characteristics values of the parameters d, p, and the target nucleotide length N describe the complete composition of the crude product. From this we have developed the relation 2 - [ N/( N - 1)]/ D a, measurable( N, d) as a universal quantitative measure for multicyclic synthesis conditions ( D, fractal dimension and similarity exponent, respectively). We use this mathematical treatment to compare the efficiency of oligodeoxyribonucleotide syntheses of different target length N on polymer support materials. Further, we analyze selected syntheses of suort and long oligodeoxyribonucleotides as well as single-stranded DNA sequences by well-known empirical autocorrelation, fast Fourier transformation, and embedding-dimension techniques.

Fractal and Dendritic Growth of Surface Aggregates

ABSTRACTThe similarity of patterns formed in non-equilibrium growth processes in physics, chemistry and biology is conspicuous and many attempts have been made to discover common mechanisms underlying their growth. The central question in this context is what causes some patterns to be dendritic, as e.g. snowflakes, while others grow fractal (randomly ramified). Here we report a crossover from fractal to dendritic patterns for growth in two dimensions: the diffusion limited aggregation of Ag atoms on a Pt(111) surface as observed by means of variable temperature STM. The microscopic mechanism of dendritic growth can be analyzed for the present system. It originates from the anisotropy of the diffusion of adatoms at corner sites which is linked to the trigonal symmetry of the substrate. This corner diffusion is observed to be active as soon as islands form, therefore, the classical DLA clusters with the hit and stick mechanism do not form. The ideas on the mechanism for dendritic growth have been verified by kinetic Monte-Carlo simulations which are in excellent agreement with experiment.

Can We Define Indispensable Amino Acid Requirements and Assess Protein Quality in Adults?

Adult indispensable amino acid (IAA) requirements, as exemplified by lysine, are examined in a metabolic framework in which dietary IAA are needed to replace both regulatory losses (extrinsic and adaptive IAA oxidation) and obligatory losses (intrinsic metabolic consumption). Thus requirements need to be defined as minimal, operational and optimal. For minimal needs, animal studies show different patterns for maintenance and growth, with lower lysine and leucine in the former compared with the latter pattern, which mirrors tissue protein. Reliable human studies also confirm a low minimum lysine requirement, 15 mg/kg or less, compared with growth needs, supporting the 1985 FAO adult value and lower than the value for preschool children proposed as the basis of a scoring pattern for adults by FAO/WHO in 1991. This pattern derives from studies in children depositing considerable nitrogen and is unsuitable for an adult scoring pattern. Stable isotope lysine balance studies do not provide unequivocal support for an increased minimum requirement value for lysine. As for operational requirements, these are higher because of increased regulatory losses due to the higher intakes of IAA in habitual diets and because of the diurnal feeding pattern. Definition of optimal needs requires value judgements of the beneficial metabolic influence of intakes in excess of minimal. This influence (the anabolic drive) is a tangible phenomenon in growing animals, but is yet to be identified in humans. Thus optimal requirements are not yet definable, and there is no suitable scoring pattern to replace the 1985 FAO values, which may accurately reflect minimal needs.

Photosynthesis and Production of Epilithic Algal Communities in Thingvallavatn

Epilithic algal communities in Lake Thingvallavatn have different species- and depth-specific patterns for growth and for photosynthesis and respiration. The estimated specific photosynthesis (P max ) was relatively low, and decreased with increasing depth from 1.56 to 0.85 mg O 2 mg #751 chlorophyll a h #751 . A similar decrease in dark respiration rate was observed. In the laboratory experiments on natural epilithic communities 68 to 79% of the variation in photosynthetic rate (mg O 2 m #752 h #751 ) was explained by irradiance, 0.4 to 8% by temperature, and 2 to 5% by biomass (...)

The Resistance of Dunaliella acidophila against Heavy Metals: The Importance of the Zeta Potential

Summary The resistance of photosynthesis and growth of the acid-resistant green alga Dunaliella acidophila (optimal growth at pH 1.0) and the salt-resistant Dunaliella parva (grown at pH 7.6) against Al(III), La(III), Cu(II), Cd(II), Hg(II) (applied as chlorides) and W(IV) (applied as Na 2 WO 4 ), and the effects of these compounds on the zeta potential of the cells were measured in glycerol media of comparable ionic strength. Dunaliella cells with a positive zeta potential ( Dunaliella acidophila , pH 1–2) are extremely resistant to toxic di- and trivalent cations, but are sensitive to toxic anions. On the other hand, cells with a negative zeta potential ( D. acidophila and D. parva , pH 7.0) are resistant to toxic anions, but sensitive to toxic cations. The non-dissociated HgCl 2 causes similar inhibitions of photosynthesis in both Dunaliella species, independent of the pH of the medium. Di- and trivalent cations cause an increase of positive zeta potentials, but a decrease of negative zeta potentials. Toxic polyvalent anions decrease positive zeta potentials, but increase negative zeta potentials. Almost no effect of HgCh on the zeta potential was observed. The results demonstrate that the zeta potential plays an important role in cation and anion toxicity. The interpretation of effects of toxic ions on growth is more difficult than the interpretation of the effects of these ions on photosynthesis, since the chemical composition and electrical properties of the culture media are very different, leading to different activity coefficients of the toxic ions as well as competition effects between non-toxic and toxic ions. This applies especially to divalent cations, whereas trivalent cations exhibited similar differential inhibition patterns for growth to those observed for photosynthesis. The actual sensitivity of growth of D. parva cells to toxic divalent cations was masked by the high salinity of the culture medium: The growth of D. acidophila e.g., was more sensitive to Cu(II) than the growth of D. parva . Mechanisms of toxicity of polyvalent cations and anions are discussed as well as the ecophysiological benefit to an acidophilic organism of high resistance against heavy metals.

Simulated caustic patterns for dynamic crack growth in a plate based on a three-dimensional numerical analysis

The rapid growth of a through-the-thickness crack in a nominally elastic plate under Mode I conditions is considered, with emphasis on the three-dimensional aspects of the elastodynamic crack growth process. For points near the crack edge, the assumptions on stress state consistent with plane stress analysis are not valid, and the possibility of an inertial effect associated with rapid lateral contraction must be considered. The steady crack growth process is analyzed here by means of the finite element method, and the degree to which the local fields are described by plane stress analysis is established. In addition, synthetic shadow spot patterns are generated from the numerical three-dimensional solutions. The inferred values of stress intensity factor are compared with the values of the corresponding plane stress dynamic stress intensity factor.

Effect of stocking rate, fodder conservation and grazing management on the performance of wether sheep and pastures in south-west Victoria. 2. Seasonal wool growth rate, liveweight and herbage availability

The effects of stocking rate, level of fodder conservation and grazing management of Polwarth x Corriedale wethers on the seasonal wool growth rate, liveweight and herbage on offer over a three year period have been examined by pattern analysis. The grazing management systems were continuous, deferred and rotational grazing. The herbage on offer in the autumn and spring of two years, the minimum liveweight in winter for each of three years, and monthly wool growth rates were analysed by regression. The grouping of treatments with similar patterns of seasonal fluctuations indicated some effects due to the treatments and these indications were supported by the regression analysis. Stocking rate was shown to have a major effect on the distribution and amount of feed on offer, especially in the continuous system. Differences between stocking rate in the herbage on offer were reduced by the rotational grazing system, and the deferred system increased the autumn supply of herbage. These general effects were also reflected in the seasonal patterns for wool growth and, to some extent, liveweight. The effect of fodder conservation on herbage availability showed two distinct and opposing responses one during the feeding and the other during the period when hay is conserved. Responses in herbage availability were apparent in late autumn, but by late winter any residual effect on liveweight was small. In the drought conditions of 1967 there was a substantial response in the minimum liveweight in winter to the conservation practice.

Mouse teratocarcinoma: Carbon source utilization patterns for growth and in vitro differentiation

Carbon source utilization patterns for both in vitro growth and differentiation of the embryonal carcinoma line PCC3/A/1 have been investigated. Whilst a number of carbon sources can support growth, the presence of glucose appears critically necessary for in vitro differentiation to reach completion. In the absence of glucose, differentiation is apparently blocked during the second part of the differentiation period. This observation has allowed the isolation of cell variants from PCC3/A/1. Some of the results of a preliminary characterization of such cell lines are discussed.

Cellular and geometric control of tissue growth and mitotic instability

A mathematical model is presented for the control of growth by a diffusible mitotic inhibitor. The stability of growth is examined as a function of the values of the parameters describing the production, transport and decay of the mitotic inhibitor, and also as a function of the geometry of growth of the growing tissue. Comparisons are made between patterns of mitosis in the mathematical model and experimentally observed mitotic patterns in tissue culture experiments (Folkman & Hochberg, 1973). It is shown that cellular parameters which closely reproduce mitotic patterns for growth as a three-dimensional sphere, lead to self-limiting growth in three dimensions but limitless growth in two dimensions. This observation, that the stability of growth can depend on the geometry of growth is in agreement with earlier results from tissue culture experiments of Folkman & Hochberg (1973). Experimental approaches which can be used to study the relative effects of vascularization, nutrition, mitotic inhibition and growth geometry in normal and cancerous growth are suggested.

Nutritional Aspects of Metabolism of Growth and Development

A growth pattern that is normal for the first half year of life with growth failure and partial recovery during the next three or four years is common in many developing countries. Biochemical evidence of anemia, hypoproteinemia, and a varying spectrum of relative vitamin deficiency is also found. Similar patterns for growth and biochemical findings were found in a group of hospitalized infants in the United States. The multiple conditioning factors in the development of these patterns are emphasized.

Nutritional aspects of metabolism of growth and development

A growth pattern that is normal for the first half year of life with growth failure and partial recovery during the next three or four years is common in many developing countries. Biochemical evidence of anemia, hypoproteinemia, and a varying spectrum of relative vitamin deficiency is also found. Similar patterns for growth and biochemical findings were found in a group of hospitalized infants in the United States. The multiple conditioning factors in the development of these patterns are emphasized.

Book Note and Review: Personnel: Developing Executive Skills: New Patterns for Management Growth

Book Note and Review: Personnel: Developing Executive Skills: New Patterns for Management Growth

Developing Executive Skills: New Patterns for Management Growth.

Developing Executive Skills: New Patterns for Management Growth.

Human Fertility in Latin America

The rate of growth of the population of Latin America is higher than that of any other continent and almost certainly higher than in any major region in the world today. This rapid growth has resulted primarily from a substantial decline in mortality, reinforced by immigration, superimposed on a high level of human fertility. The average annual birth rate in Latin America during the period 1950-55 was about 42 per 1,000 population, compared with 25 in the United States, and 28 in Canada, over the same period. This paper deals with levels and trends of human fertility in Latin America, differential fertility, social and psychological factors associated with prevailing patterns of reproduc tion, the implication of these patterns for future population growth, and the prospects for a decline in fertility in the near future.