Jump landing performance in footballers

Dieen, J.H. van [Promotor]Kingma, I. [Copromotor

Nuclear fusions contribute to polyploidization of the gigantic nuclei in the chalazal endosperm of Arabidopsis

Somatic polyploidization is recognized as a means to increase gene expression levels in highly active metabolic cells. The most common mechanisms are endoreplication, endomitosis and cell fusion. In animals and plants the nuclei of multinucleate cells are usually prevented from fusing. Here, we report that the nuclei from the syncytial cyst of the chalazal endosperm of Arabidopsis thaliana (L.) Heynh. are polyploid with some intermediate ploidy levels that cannot be attributed to endoreplication, suggesting nuclear fusion. Analysis of isolated nuclei, together with fluorescent in situ hybridization (FISH), revealed that nuclei from the chalazal endosperm are two or three times bigger than the nuclei from the peripheral endosperm and have a corresponding increase in ploidy. Together with the consistent observation of adjoined nuclei, we propose that nuclear fusion contributes, at least in part, to the process of polyploidization in the chalazal endosperm. Confocal analysis of intact seeds further suggested that free nuclei from the peripheral endosperm get incorporated into the chalazal cyst and likely participate in nuclear fusion

PENGARUH TEKANAN DAN SUHU TERHADAP KERAPATAN DAN NILAI KALOR BRIKET ARANG LIMBAH SERBUK MERANTI MERAH

This study aims to determine the effect of pressure and temperature on the density and calorific value of red meranti sawdust charcoal briquettes (Sorea. selanica). This study used a factorial complete randomized design with 3 replications. Factors used are A factor (pressure 1 ton, 2 tons and 3 tons) and B factor (temperature 100ºC, 200ºC and 300ºC).  The results showed that the highest density based on the pressure factor (A) was 3 tons (a3) of 0.478 gm/cm3 and the lowest was in the 1 ton (a1) treatment of 0.377 gm/cm3, while based on temperature (B) the highest was in the 300ºC temperature treatment ( b3) of 0.479 gr/cm3 and the lowest at 100ºC (b1) of 0.378 gr/cm3. The highest calorific value based on the pressure factor (A) is 2 tons (a2) of 3734.3991 cal/gram and the lowest is in the 1 ton (a1) treatment of 3731.6027 cal/gram, while based on the temperature treatment (B) the highest is at a temperature 200ºC (b2) of 3835.3992 cal/gram and the lowest at 100ºC (b1) of 3732.6028 cal/gram, lower than the Indonesian National Standard. The pressure factor (A) have an effect on the density and calorific value while the temperature factor (B) and the interaction AB has no effect. &nbsp

Floating Park Sebagai Penunjang Waterfront City Dan Solusi Terhadap Kebutuhan Ruang Terbuka Hijau Dalam Wilayah Perkotaan

Karya tulis ini bertujuan untuk mempelajari mengenai Floating Park dalam fungsinya sebagai lahan tambahan untuk taman publik. Penyajian masalah berkaitan dengan konsep waterfront, penyediaan Ruang Terbuka Hijau, serta solusinya berupa taman publik pada struktur terapung. Dalam pembahasannya menyajikan mengenai sistem struktur, persyaratan berkaitan dengan lingkungan dan berbagai fasilitas yang direncanakan. Penyajian data diperoleh dari hasil studi literatur. Dari keseluruhan penulisan diperoleh hasil bahwa Floating Park dapat menjadi sebuah solusi alternatif bagi penyediaan Ruang Terbuka Hijau (RTH) untuk area perkotaan. Solusi tersebut khusus memperhatikan aspek struktural dan lingkungan air sebagai konteks, sesuai dengan kondisi yang beragam di lapangan. Selain itu juga memperhatikan ketersediaan fasilitas penunjang mengingat fungsinya sebagai taman publik

SIFAT FISIS BAMBU SEPANJANG BATANG PADA BAMBU SERO (Schizostachyum brachycladum Kurz.)

The objective of this study was to analyze the effect of internode position along the culm on the physical properties of sero bamboo. This study used a randomized complete block design with internode position along the culm as the treatment effect, comprising six levels, i.e., 0, 20, 40, 60, 80, and 100%, using four bamboo culms as blocks. The observed response variables were the bamboo's physical properties, such as green and air-dry moisture content, radial, tangential, longitudinal shrinkage, and specific gravity. The result of the study showed that green moisture content radial and tangential shrinkage, statistically, were influenced by their locations along the culm. In contrast, air-dry moisture content, longitudinal shrinkage, and specific gravity were independent of their locations along the culm

Рецензія на монографію І.С. Чекмана «Нанофармакологія»

Рецензія на монографію І.С. Чекмана «Нанофармакологія» К.: Задруга, 2011. – 424 с

Cytodifferentiation during callus initiation and somatic embryogenesis in Zea mays L. : [Cytodifferentiatie tijdens callusinitiatie en somatische embryogenese in Zea mays L.]

This thesis deals with cytomorphogenic aspects during various phases of regeneration in tissue cultures of Zeamays L. Regeneration through tissue culture has been shown in an increasing number of plant species and is applied on large scale in agriculture and horticulture. Nevertheless, several fundamental scientific data are lacking, which hampers further development of tissue culture, particularly where it concerns tissue culture of monocotyledoncus crops. For example, callus initiation and somatic embryogenesis are important processes during plant regeneration, which can be induced and controlled increasingly with success. However, basic knowledge with regard to these processes is often confined to dicotyledonous crops. In particular, information is lacking about structural changes at the cellular and subcellular level. Research on callus initiation and somatic embryogenesis in maize by structure analysis at the light and electron microscopical level therefore can lead to a better understanding of in vitro cultures, surely for maize, but possibly for monocotyledons in general.Chapter 1 gives a survey of the present information on callus initiation, callus development and somatic embryogenesis. At the end of this Chapter the aim of the thesis is described.In Chapter 2 callus initiation is described based on the results obtained from a light and electron microscopical study. A comparison is made between two inbred lines, A188 and A632, which differ in culture resonse. The initiation of callus in immature embryos has come about within three days after the onset of culture. The first day of culture is characterized by an increase in the number of cell organelles, changes in vacuolation and in nucleolar morphology. These ultrastructural changes take place in embryos of both genotypes and are not affected by 2,4D. After the first day of culture changes occur, dependent on genotype and culture conditions. In embryos of the A188 line a broad meristematic zone develops in the middle and basal scutellum under the influence of 2,4D. From this region somatic embryos and embryogenic compact callus arise. A second meristematic region is observed around the coleorhiza. In embryos of the A632 line callus formation occurs only around the coleorhiza. This callus tissue is non-embryogenic and not capable to regenerate. In the period of callus initiation a shock response can be discerned from a growth response. The shock response takes place in the whole scutellum of both genotypes during the first day of culture and is not affected by 2,4D. On the other hand, the growth response is a local event, after the first day of culture under the influence of 2,4D.In Chapter 3 the period of callus initiation is studied using autoradiography. Special attention was paid to the fraction of cells with DNA synthesizing activity and to the mitotic index in different scutellum regions. It appears that the shock response and the growth response also become manifest during the cell cycle. Moreover, the variation in culture response between the different regions of the scutellum is also expressed in the course of the cell cycle. We observed, that cells in the top of the scutellum terminate their DNA synthesizing and mitotic activity during the growth response, while cells in the middle and basis clearly retain these activities. The results further suggest that scutellum cells preferentially arrest in the G2 phase of the cell cycle during the first eight hours of culture.In the Chapters 4 and 5 the development of the embryoids via an embryogenic callus phase is described for the inbred line A188. Compact callus develops from the embryo when cultured on MS medium with 6% sucrose, whereas friable callus arises on N6 medium with 2% sucrose. Both callus types originate from the abaxial region of the scutellum. After a few days on N6 medium the scutellum is transformed into an almost translucent and soft callus tissue with a fragile appearance. This friable callus is composed of long aggregates of large vacuolated cells and embryogenic units, groups of small isodiametric cells. The cell aggregates are surrounded by large intercellular spaces, which gives the callus its fragile appearance. This friability is caused by cell dissociation between embryogenic cells as well as non-embryogenic cells, cell proliferation in the embryogenic unit and elongation and degeneration of the non-embryogenic cells. No vascular tissue is observed in friable callus. Transport of nutrients probably takes place through the intercellular spaces by diffusion. Compact callus is more organized; it contains vascular bundles around a centre of parenchyma cells, while intercellular spaces are lacking.Somatic embryogenesis in friable callus cultures starts with the transition of an unorganized embryogenic unit to an organized structure of embryogenic cells with a coordinated growth. The transition unit is regarded as an intermediate stage between the embryogenic unit and the somatic embryo. It is a globular structure with a distinct morphological difference between the apical cells and the basal cells that are connected with the callus. In this transition unit a polarity is established, which possibly leads to a gradient of hormones and nutrients. This polarity contributes to an important extend to the activation of somatic embryogenesis. The appearance of large numbers of microtubules in somatic embryos confirms the transition to a coordinated growth. The early somatic embryogenesis strongly resembles the zygotic embryo development with respect to shape and structure. The inability of the embryoid to develop beyond the late globular stage in the presence of 2,4D is probably due to the repressive effect of the auxin on the growth of the shoot apex.Chapter 6 shows the results of the study on the utility of isozymes as biochemical and cytochemical markers in tissue cultures of maize. The zymograms of glutamate dehydrogenase (GDH), peroxidase (PRX) and acid phosphatase (ACP) were analysed in different callus cultures. Variation was demonstrated in the isozyme patterns of GDH and PRX between embryogenic and non-embryogenic callus. Some isozyme bands appeared to correlate with the degree of organization, while the activity of other isozymes was dependent on the length of the culture period. When the same enzyme assays were carried out in situ on fresh callus samples, it appeared that only a clear discrimination in enzyme activity between embryogenic and non-embryogenic was possible with the GDH assay. Therefore, GDH is regarded as an useful biochemical and cytochemical marker in embryogenic callus of maize.In Chapter 7 it is demonstrated, that during pollen embryogenesis in maize, early microspores develop in multicellular pollen grains which consist of cells that differ in vacuolation. During the development repeated divisions especially take place in the vegetative cell. Although participation of the generative cell to the formation of the multicellular pollen grain can not be excluded, it is assumed, that in our experiment the multicellular pollen grain is mainly derived from the vegetative cell.In Chapter 8 the information, obtained from the Chapters 1 to 7, is summarized in the subjects callus initiation, callus development and somatic embryogenesis and provided with comments. At the end a hypothesis is formed, in which the different ways of regeneration are classed in one scheme. In this concept it is assumed that the regenerative capacity is genetically controlled and the expression of the genes becomes manifest under permissive conditions.</TT

The functional response to prey density in an acarine system

Predacious mites are considered to be important natural enemies of phytophagous mites. Their efficiency in the natural control of prey populations depends on the relationships of the number of prey killed per predator per time unit and the oviposition rate on the one hand and prey density on the other hand. These relationships determine the functional and the numerical response of the predator population to the prey density. The shape of these responses indicates to what extent the mortality of the prey population will be raised by an increase of the prey density. When the mortality rate is increased to such an extent that it exceeds the reproduction rate of the prey population at a certain value of the prey density, a necessary condition for the regulation of the prey would be satisfied. Through the operation of such a regulating mechanism the predator and the prey population may remain present at low levels, which gives protection against outbreaks of harmful prey species.Curves of the functional response of Typhlodromus occidentalis females to the density of Tetrapychus urticae eggs and males on disks of bean leaf have been obtained experimentally by Kuchlein (in preparation). The curves do not correspond with the fundamental types distinguished by Holling (1959a, 1961). This study is an attempt to explain these curves and to find out on which conditions T. occidentalis can regulate prey species such as T.urticae. For that purpose simulation models were constructed to compute the relevant components of the behaviour of the predator and the prey, the state variables of the predator-prey system, and the resulting predation rates at different prey densities. In this system approach different system elements are distinguished. The components of behaviour considered are the proportion of encounters between the predator and the prey resulting in a capture (the success ratio), the length of handling periods, the coincidence in space, and the locomotion activity and velocity of the predator and the prey. The state variables considered are the engagement of the predator in searching and handling prey, the actual prey densities, the hunger of the predator, and the density of the webbing cover produced by the T.urticae males. A quantitative measure of the degree of satiation of the predator was found in the gut content; a measure for the relative density of the webbing cover in the proportion of grains free from the leaf's surface when the leaf disk is sprayed with a fine powder.To compute the gut content in the simulation of the predation process it is necessary to know the rate of ingestion when the predator feeds on a prey, and the rate of evacuation of food from the gut (denoted by digestion). Feeding experiments with radioactive prey revealed that the ingestion rate is not constant, but depends on the gut content of the predator and on the availability of food in the prey. The rate is higher when the prey is a T.urticae egg, than when it is a male. The maximum gut content was computed to be 1.08 prey egg equivalents, the maximum food contents of eggs and males found are 0.94 and 0.67 egg equivalents respectively. The digestion rate is assumed to be proportional with the gut content. The coefficient of this proportionality, obtained from the restoration of the behaviour during a long digestive pause, measured 0.435 hour -1.The relationship between the relative density of the webbing cover and the total distance walked by the males on the leaf disk has been defined quantitatively. The production of webbing is gradually reduced, or the males tend to walk along the same pathways.Leaf disks were prepared with a standardized adult female T. occidentalis (with an empty gut and two days old), or with a normal ovipositing female, and a different number of T.urticae eggs or males. These disks were observed continuously and the events occurring were recorded chronologically. The locomotion velocity of the predator and the males, and the locomotion activity of the males was measured during this observation. From the records of events a computer program derived for a series of gut-content classes, the mean values of the resting period and the walking period of the predator, the coincidence in space and the success ratio for different encountering situations, the proportion of disturbance in encounters of active males and a resting predator, and the handling and feeding periods.The velocity of the standardized predators did not differ significantly before and after feeding on the first prey (1.15 and 1.12 m/hour respectively).Oviposition by the predator slightly increases the predation rate by raising the success ratio, but reduces the locomotion velocity. The success ratio of standard predators was four times higher than the success ratio in Kuchlein's experiments, which was accounted for in the simulation models.The multiple relationships between the components of behaviour and the state variables were evaluated by partial correlation analysis and polyfactor analysis. The latter method provided quantitative descriptions of the relevant, curvilinear relationships by an iterative procedure for multiple regression. These descriptions were used in the models for simulation of the predation process.CSMP programs for three kinds of models are described to simulate a predation process on a computer, each dealing with chance variables in a different way. A deterministic model gives erroneous results as soon as the predation rate is a curvilinear function of stochastic variables, whereas a stochastic model consumes too much computer time. An intermediate approach applies deterministic simulation to classes of the stochastic variables in a hypothetical population of predators. The classes in this method of compound simulation are chosen in such a way that within the classes the relationship with the predation rate is approximately linear. The classes contribute to the expectation value of the output variables on the base of the relative frequency distribution of the predators over the classes. The three types of models were applied to simulate the predation process with prey eggs only. The most comprehensive model for the predation of prey eggs and males was built according to the principles of compound simulation. It computes expectation values of the numbers of prey eggs and males destroyed, the biomass consumed, the gut content and occupation of the predator, the actual prey densities, the instantaneous prey mortality and prey utility, and the relative density of the webbing cover as a function of time, the prey density maintained, and the prey replenishment interval. Compound simulation can be applied to study all sorts of stochastic processes.The results of simulation lead to the following conclusions with respect to T. occidentalis and T. urticae :All functional response curves obtained by simulation deviate from the fundamental types of Holling. These deviations are discussed and explained with the help of the values of the components of behaviour at the different prey densities.Hunger exerts an important influence on predation. The success ratio decreases with increasing gut content, which relationship is the main determinant of the functional response to prey density. There is no distinct threshold-value of the gut content for the evocation of attacks. Hunger induces a long feeding time and a high ingestion rate, and hence a better utilization of the prey captured. At all hunger levels a prey egg provides more food than a prey male.In mites, which are deprived of food for a different number of days, the difference in hunger level will be negligible. Differences in behaviour demonstrated by such mites will not be effected by hunger, but rather by starvation.The success ratio seems to be reduced by a high frequency of encounters with prey. Probably predation by mites can be inhibited at a high prey density by stimulus satiation.Webbing produced by the prey reduces the encountering rate of the predator and the prey, the locomotion velocity and activity of the predator, and the handling time for prey males. It increases the velocity of the prey males, but in general reduces the predation rate, because it has a distinct barrier effect. Other factors related to prey density are the disturbance by active males and the aggregation of the males. Disturbance reduces the mean period of resting and extends the mean period of walking, increasing the predator activity and the encountering rate. Disturbance of feeding predators does not affect the success ratio. Aggregations of males reduce the rate of encounters between the predator and active males, and the activity of the males. Satiation, prey aggregation and the production of webbing are the main factors determining the shape of the functional response of T.occidentalis to the density of T. urticae males on leaf disks.The prey mortality rate and the prey utility depend on the gut content of the predator. The ratio of the mortality rate or the utility of different prey species is not constant, but changes with the gut content. This induces switching from one kind of prey to another at increasing prey density.The influence of prey replenishment on the functional response curves is almost negligible for an exposition time of six hours. In general the predation rate will be underestimated for low prey densities when the prey captured is not replenished in experiments.The number of eggs laid per 24 hour by the predator is about four times its mean gut content. This linear relationship between the oviposition rate and the gut content implies a numerical response of the predator population to prey density, which is most intensive at prey densities below five eggs or males per cm 2.The combined effect of the functional and the numerical response to prey density is indicated by the prey risk induced by the next generation of predators as a function of current prey densities. Such total response curves show a steep rise to a maximum of 2.4 prey eggs or 2.0 prey males per cm 2, and a gradual decline beyond these prey densities. It has been computed that an equilibrium density of at least 0.006 predators per cm 2at a prey density below 2.4 eggs per cm 2is a necessary condition for 'short term' regulation of the prey population by predation of eggs. A high predator mortality can inhibit such a regulation. The expectation value of the reproductive period of the newborn predators must not be lower than 0.95 days for predation on eggs, and 1.92 days for predation on males.Some conclusions derived in this book concern general aspects of predation:It seems to be indispensable in the study of predation to take account of the stochastic character of predation processes with a single predator. Deterministic simulation models can give incorrect results.In natural systems the functional responses of predators to prey density will be multiform, and very probably most of them will differ from the fundamental types described by Holling (1959a, 1961).Predators need some time to adapt their mean gut content to a new prey density. The adaptation time is longer at a low prey density, than at a high one. This may lead to an overestimation of the predation rate at low prey densities, when starved predators are used in experiments with a short exposition time.Hunger dependent switching can contribute to the regulation and stabilization of the prey species preferred at a low hunger level.The contribution of chemical control measures to the mortality of predacious mites can release populations of their prey species.It can be advantageous to introduce, simultaneously with the predator, a harmless and rather unattractive alternative prey species.Finally some suggestions are given to build a submodel of the multiple functional response to the densities of several kinds of prey into models for simulation of the dynamics of predator and prey populations