Species number, historical elements and protection of threatened species in the flora of Helsinki, Finland

Recent urban ecological research shows high species numbers in slowly developed cities and towns. Urban development is known to fragment, change and weaken urban biodiversity. Conservation areas have been the main tool in protecting threatened species both in rural and urban municipalities in Finland. However, very little is known about how successful conservation areas are in protecting rare and threatened species and their habitats in boreal cities and towns. Helsinki, the capital of Finland, is a rapidly urbanising hemiboreal city, which has a high number of vascular plant species in both native and urban biotopes. One and 0.25 km² grid square maps and simple overlay methods are being used to analyse data on species occurrence and land use. Total species number, a rarity index and historical and threatened groupings are used to classify species and their habitats. At present, conservation areas can protect only a small proportion of threatened species in Helsinki. More protection areas, green areas in future land-use decisions and new management goals are needed to protect the biodiversity of existing vascular plant species.     

Language-theoretic aspects of DNA complematarity

The optimism about the possibilities of DNA computing is based on two central issues: the Watson–Crick complementarity and the massive parallelism of DNA strands. While the latter issue renders exhaustive searches possible and thus may settle problems previously considered intractable, the former issue is the cause behind the universality of many models of DNA computing. Moreover, complementarity can be viewed as a purely language-theoretic operation: undesirable circumstances in a string trigger a transition to the complementary string. This aspect of complementarity is investigated in the present paper, mainly from the point of view of L systems. New types of word sequences will be discovered. Sometimes the resulting decision problems are equivalent to well-known open problems from other areas.     

Effect of start-up schemes and amplitude of tangential motion on friction behavior in fretting point contact

The friction coefficient is an important factor in fretting fatigue. The frictional behavior of quenched and tempered steel 34CrNiMo6 was studied in smooth fretting point contact with measurements at partial and gross slip conditions. The effect of the start-up scheme is studied by altering the way the displacement amplitude is developed to the target value. This only has a minor effect on the maximum friction coefficient but it does alter the frictional behavior. The friction coefficient increases as tangential displacement amplitude is increased and it has a maximum value of 1.5-1.6 at the transition to gross sliding.     

Nanofibrillated cellulose,poly(vinyl alcohol), montmorillonite clay hybrid nanocomposites with superior barrier and thermomechanical properties

Nanocomposites of poly(vinyl alcohol) (PVA), nanofibrillated cellulose (NFC), and montmorillonite (MMT) clay were prepared via solvent casting. In addition to investigating the effect of clay loading, PVA matrices crosslinked with poly(acrylic acid) (PAA) were prepared and compared with linear (noncrosslinked) PVA nanocomposites. ¹³C NMR and infrared spectroscopy confirmed the presence of crosslinks. Scanning electron microscopy revealed effective NFC and MMT clay dispersion throughout the nanocomposites, while X‐ray diffraction highlighted the effectiveness of PAA to encourage clay dispersion. MMT clay provided a barrier against the diffusion of water and oxygen (molecules) through the nanocomposite films. Permeability and adsorption were further reduced by crosslinking, while oxygen barrier properties were remarkably enhanced at elevated relative humidities. Thermal stability of the PVA segments was strengthened by the presence of MMT clay and crosslinks. MMT clay–reinforced PVA and NFC within the films, increasing the Young's modulus, tensile strength, and glass transition temperature. Crosslinking further enhanced the thermomechanical properties by imparting physical restraints on polymer chain segments, providing elasticity, and ductility. The hybrid films were successfully reinforced at elevated humidities, with nanocomposites displaying enhanced storage moduli and near‐complete recovery. POLYM. COMPOS., 35:1117–1131, 2014. © 2013 Society of Plastics Engineers     

In sweet harmony or in bitter discord? How cultural values and stakeholder requirements shape and users read an urban computing technology

AI & SOCIETY - Culture is, in many ways, implicated in and shapes technology design and use. Inspired by Stuart Hall’s conception of encoding/decoding, we maintain that technological...     

Conformal Hermetic Sealing of Wireless Microelectronic Implantable Chiplets by Multilayered Atomic Layer Deposition (ALD)

A hermetic sealing method of sub‐millimeter‐sized microelectronic chiplets for wireless body implants is presented by ultrathin and electromagnetically transparent atomic layer deposition (ALD) coatings. Fully 3D conformal encapsulation of wirelessly powered microdevices is demonstrated both with and without opening windows for electrophysiological measurements. The chiplets embedding custom application‐specific integrated circuits (ASICs) with radio frequency (RF) transmitters are encapsulated by a stack of alternating layers of hafnium oxide and silicon dioxide to maximize impermeability of water and ionic penetration while minimizing the volume of the packaging material. The hermeticity of the devices is characterized through accelerated aging tests in saline at T = 87 °C, while continued functionality is monitored via evaluation of backscattered RF signals (near 1 GHz) to ascertain possible degradation and electronic failure. Earliest failures of wirelessly functional devices occur after more than 180 d of immersion at 87 °C. Wireless devices having opening windows through the ALD envelope show no signs of degradation for >100 d. This implies an equivalent lifetime >10 years at T = 37 °C. This approach is readily scalable to high throughput batch processing of hundreds of microchiplets, offering a methodology for hermetic packaging of microscale biomedical chronic implants.     

Power and size of extended Watson–Crick L systems

A Watson–Crick D0L system is a language-theoretic model which is based on a D0L system and a letter-to-letter morphism, representing the Watson–Crick complementarity phenomenon of DNA. The two components are connected by a triggering mechanism. The computational capacity of these constructs is of particular interest. In this paper we prove that if the underlying systems are EDT0L systems or E0L systems, then these constructs are able to generate any recursively enumerable language. Moreover, to reach this power, Watson–Crick EDT0L systems with either two tables or a bounded number of non-terminals suffice.     

Biomanipulating the drinking water reservoir of Estonia's capital city: Prospects for success

The possibility of utilizing biomanipulation to improve the water quality of Tallinn's drinking water reservoir (Lake Ülemiste) was analysed on the basis of water quality data, test fishing by different methods, and earlier studies on aquatic plants, light climate and sediments. Eutrophic, polymictic Lake Ülemiste is characterized by a prevalence of high filamentous cyanobacteria biomass, rotifers in the zooplankton community, mature bream in the fish biomass, and a high density of planktivores (YOY perch). Several prerequisites for being a potential target for biomanipulation were identified, including (i) decreased external total phosphorus (TP) loading; and (ii) a sufficient stock of piscivorous fish in the lake. Prohibition of fishing should favour biomanipulation efforts. The potential for recolonization of macrophytes and large Daphnia species in Lake Ülemiste could be judged from historical data. The in-lake TP concentrations are within the limits that facilitate successful restoration. As phytoplankton biomass was significantly limited by phosphorus in Lake Ülemiste, its water quality improvement will be driven primarily by reduced nutrient concentrations, and then by zooplankton grazing. Internal TP loading and a new phytoplankton species community were assessed as major challenges for successful implementation of biomanipulation as a means of improving the water quality of Lake Ülemiste.