Asynkronisen ohjelmoinnin tekniikoiden vertailu Node.js-ympäristössä

Työn tarkoitus oli selvittää, mitä tekniikoita asynkroniseen ohjelmointiin on saatavilla, mitä heikkouksia ja vahvuuksia niillä on ja millaisiin tilanteisiin kukin tekniikka sopii parhaiten. Asynkronisella ohjelmoinnilla tarkoitetaan sitä, ettei ohjelman käskyjä suoriteta siinä järjestyksessä, missä ne esiintyvät lähdekoodissa. Työssä esiteltiin aluksi synkroninen ja asynkroninen ohjelmointi, sekä asynkroniselle ohjelmoinnille saatavilla olevat tekniikat ympäristöstä huolimatta. Työn vertailu rajattiin kolmeen Node.js-ympäristössä saatavilla olevan asynkronisen ohjelmoinnin tekniikan vertailuun: takaisinkutsufunktioihin, async-apufunktiokirjastoon sekä lupauksiin (promises). Vertailussa kuvailtiin kolme erilaista ongelmaa, joiden ratkaisut toteutettiin käyttäen kutakin vertailtavaa asynkronisen ohjelmoinnin tekniikkaa. Jokaisella ongelmalla oli myös erilainen samanaikaisuusvaatimus. Vertailun mittareina käytettiin käyttäjäkoodin luettavuutta, kompleksisuutta, suorituskykyä sekä käytettävyyttä. Tuloksista kävi ilmi, että ongelmien eri vaatimuksista huolimatta lupaukset osoittautuivat parhaaksi tekniikaksi, kun kaikkien mittareiden yhteisvaikutus otetaan keskimäärin huomioon. Lupaukset käyttivät kuitenkin hieman enemmän muistia kuin muut tekniikat.The purpose of this thesis was to find out what asynchronous programming techniques are available, what are their weaknesses and strengths and to what situations each technique is best suited for. Asynchronous programming means that a program's instructions are not executed in the same order as they appear in the source code of the program. First synchronous and asynchronous programming and the techniques available for asynchronous programming regardless of environment were introduced. The comparison was restricted to three asynchronous programming techniques available in Node.js: callback functions, the async helper function library and promises. For the comparison three different problems were described whose solutions were implemented using each of the selected techniques to be compared. Each problem had a different concurrency requirement. The criteria used for the comparison were readability and complexity of user code, performance and usability. The results indicated that despite the differences in requirements of the problems, promises were the best technique when all the criteria are considered together overall. On the other hand, promises used slightly more memory than the other techniques

Embryological features, pollen and seed viability of Arnica montana (Asteraceae) – a threatened endemic species in Europe

The embryological features, mode of reproduction and reproductive capacity (pollen and seed viability) on two naturalized populations of Arnica montana in Bulgaria were studied. The embryological study shows that A. montana is a facultative apomictic species in which sexual reproduction predominates. In this species, it was established that there is a comparatively high viability of the mature pollen and embryos, which enables the successful realization of its reproductive capacity. The results of the study on A. montana reveal that both sexual and asexual vegetative reproduction with rhizomes undoubtedly play more important roles than the apomixis (namely diplospory) for support and preservation of the populations

Artificial Protein Hydrogel Materials

Recombinant DNA methods were used to create a new class of artificial proteins that undergo reversible gelation in response to changes in pH or temperature. These proteins consist of terminal a-helical "leucine zipper" domains flanking a central, water-soluble polyelectrolyte segment. The formation of coiled-coil aggregates of the terminal domains in near-neutral pH solution triggers formation of a polymer hydrogel, with the central polyelectrolyte segment retaining solvent and preventing precipitation of the chains. Dissociation of the coiled-coil aggregates through elevation of pH or temperature causes dissolution of the gel and a return to the viscous behavior characteristic of a polymer solution. The pH and temperature range of the hydrogel state and its viscoelastic properties may be systematically varied through precise changes of the length, composition and charge density of the terminal and central blocks. Such control is of value in designing hydrogels with predetermined physical properties and makes these biosynthetic triblock copolymer systems attractive candidates for use in molecular and cellular encapsulation and in controlled reagent delivery

Amphiphilic Elastin-Like Block Co-Recombinamers Containing 2 Leucine Zippers: Cooperative Interplay between Both Domains 3 Results in Injectable and Stable Hydrogels

Many biological processes are regulated by reversible binding events, with these interactions between macromolecules representing the core of dynamic chemistry. As such, any attempt to gain a better understanding of such interactions, which would pave the way to the extrapolation of natural designs to create new advanced systems, is clearly of interest. This work focuses on the development of a leucine zipper-elastin-like recombinamer (ZELR) in order to elucidate the behavior of such domains when coexisting along the same molecule and to engineer reversible, injectable and stable hydrogels. The unique propensity of the Z-moiety selected to dimerize, together with the thermosensitive behavior of the ELR, which has been constructed as a thermosensitive amphiphilic tetrablock, has been engineered into a single recombinant molecule. In this molecular design, the Z-moieties are unable to form a network, while the ELR is below its Tt, thus, guaranteeing the liquid-like state of the system. However, this situation changes rapidly as the temperature increases above Tt, where a stable hydrogel is formed, as demostrated by rheological tests. The inability of the ELR molecule (without Z-domains) to form such a stable hydrogel above Tt clearly points to a positive cooperative effect between these two domains (Z and EL), and no conformational changes in the former are involved, as demonstrated by circular dichroism analysis. AFM shows that Z-motifs seem to induce the aggregation of micelles, which supports the enhanced stability displayed by ZELRs when compared to ELR at the macroscale level. To the best of our knowledge, this is the first time that such an interplay between these two domains has been reported. Furthermore, the cytocompatibility of the resulting hydrogels opens the door to their use in biomedical applications.Este trabajo forma parte de Proyectos de Investigación financiados por la Comisión Europea a través del Fondo Social Europeo (FSE) y el Fondo Europeo de Desarrollo Regional (ERDF), por el del MINECO (MAT2013-41723R, MAT2013-42473-R, MAT2012-38043 y PRI-PIBAR-2011-1403), la Junta de Castilla y León (VA049A11, VA152A12 y VA155A12) y el Instituto de Salud Carlos III bajo el Centro en Red de Medicina Regenerativa y Terapia Celular de Castilla y León

Hydration dynamics at fluorinated protein surfaces

Water-protein interactions dictate many processes crucial to protein function including folding, dynamics, interactions with other biomolecules, and enzymatic catalysis. Here we examine the effect of surface fluorination on water-protein interactions. Modification of designed coiled-coil proteins by incorporation of 5,5,5-trifluoroleucine or (4S)-2-amino-4-methylhexanoic acid enables systematic examination of the effects of side-chain volume and fluorination on solvation dynamics. Using ultrafast fluorescence spectroscopy, we find that fluorinated side chains exert electrostatic drag on neighboring water molecules, slowing water motion at the protein surface

Influence of Solute Charge and Hydrophobicity on Partitioning and Diffusion in a Genetically Engineered Silk-Elastin-Like Protein Polymer Hydrogel

The influence of solute hydrophobicity and charge on partitioning and diffusion in physically crosslinked networks of a genetically engineered SELP polymer was investigated. A series of fluorescent dyes were used to assess the impact of solute charge and hydrophobicity on release behavior. The mechanism of solute release from the SELP hydrogel appeared to vary as a function of dye hydrophobicity. The extent of FITC attachment to amine-terminated G4 dendrimers influenced SELP hydrogel partitioning more than dendrimer diffusion properties. Results suggest the possibility of controlling solute release from SELP hydrogels by modifying the hydrophobicity and surface charge of drugs and drug/polymer conjugates as well as the possibility of “designing-in” solute-specific interactions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78240/1/1235_ftp.pd

Programming Molecular Association and Viscoelastic Behavior in Protein Networks

A set of recombinant artificial proteins that can be cross-linked, by either covalent bonds or association of helical domains or both, is described. The designed proteins can be used to construct molecular networks in which the mechanism of cross-linking determines the time-dependent responses to mechanical deformation

Dynamic Behavior in Enzyme-Polymer Surfactant Hydrogel Films

Dynamic protein-polymer surfactant films are highly hydrophilic and show a soft solid to hydrogel transition upon hydration to produce a swollen hydrogel. An unusual reversible autospreading/self-folding response is observed when the water-saturated films are transferred from water into air

Behavior of the DPH fluorescence probe in membranes perturbed by drugs

1,6-Diphenyl-1,3,5-hexatriene (DPH) is one of the most commonly used fluorescent probes to study dynamical and structural properties of lipid bilayers and cellular membranes via measuring steady-state or time-resolved fluorescence anisotropy. In this study, we present a limitation in the use of DPH to predict the order of lipid acyl chains when the lipid bilayer is doped with itraconazole (ITZ), an antifungal drug. Our steady-state fluorescence anisotropy measurements showed a significant decrease in fluorescence anisotropy of DPH embedded in the ITZ-containing membrane, suggesting a substantial increase in membrane fluidity, which indirectly indicates a decrease in the order of the hydrocarbon chains. This result or its interpretation is in disagreement with the fluorescence recovery after photobleaching measurements and molecular dynamics (MD) simulation data. The results of these experiments and calculations indicate an increase in the hydrocarbon chain order. The MD simulations of the bilayer containing both ITZ and DPH provide explanations for these observations. Apparently, in the presence of the drug, the DPH molecules are pushed deeper into the hydrophobic membrane core below the lipid double bonds, and the probe predominately adopts the orientation of the ITZ molecules that is parallel to the membrane surface, instead of orienting parallel to the lipid acyl chains. For this reason, DPH anisotropy provides information related to the less ordered central region of the membrane rather than reporting the properties of the upper segments of the lipid acyl chains.Peer reviewe