785 research outputs found
Systematic review and comparison of densification effects and planning motivations
Do higher urban densities contribute to more sustainable cities and communities? This paper examines the effectiveness of higher density (as a means) for achieving sustainable urban development (the goal) following three lines of enquiry. First, a systematic review of the scientific literature (n = 229 peer-reviewed empirical studies) is presented on the effects of urban density. Second, the motivations for increasing urban density are studied in a systematic review of Swedish planning practices based on the comprehensive urban plans in 59 municipalities. Third, these two studies are compared to find matches and mismatches between evidence and practice. Although positive effects exist for public infrastructure, transport and economics, there are also considerable negative environmental, social and health impacts. This creates a challenging task for urban planners to assess the trade-offs involving densification and accommodate current urbanisation rates. Some topics are found to be over-represented in research (transport effects), seldom discussed in practice (environmental impact), and misaligned when comparing motives and evidence (social impact). Furthermore, for some topics, urban density thresholds are found that are important because they may explain some of the divergences in the results between studies. PRACTICE RELEVANCE The transfer of knowledge from research to planning practice is a serious concern as planning strategies are not aligned with scientific evidence. Planning practice in Sweden is more positive about the contribution of higher density to sustainable urban development than the results of empirical studies warrant. The largest deviation is found in relation to the social impacts of higher density where the planning arguments are not aligned with the evidence. Several reported negative effects of densification (e.g. water management, recreational infrastructure, biodiversity) are not sufficiently accounted for in Swedenâs planning policy and strategy. The narrow planning focus on decarbonising cities and densification needs to be broadened to ensure cities are resilient against the effects of climate change and include mitigation strategies to reduce negative social, environmental and health impacts. The findings can be used to develop evidence-based planning strategies. Other countries can apply this process to assess their planning strategies
The influence of tree age and microhabitat quality on the occurrence of crustose lichens associated with old oaks
Questions: How do tree age, microhabitat characteristics and epiphytic competitors affect the occurrence of crustose lichens associated with old oaks? How do microhabitat characteristics and microclimate affect the cover of competitors (bryophytes and macrolichens)? How do microhabitat characteristics corÂŹrelate with microclimatic variables?
Location: Southeast Sweden.
Methods: Eight crustose lichen species were surveyed on 165 Quercus robur trees, 17-478 years old, at three study sites. The occurrence patterns of these species were examined at two spatial scales: among trees and within trees. Occurrence patterns within trees were examined in 10 cm Ă 10 cm plots at all four cardinal aspects at different heights from 0.5 to 4.5 m above the ground.
Results: At the tree level, age-related factors were the most important predictors of species occurrence. All species were more frequent on trees > 100 years than on younger trees. At the plot level, the frequency of occurrence increased with increasing bark crevice depth. The frequencies of all study species deÂŹcreased with increasing cover of bryophytes. Bryophytes were in turn more frequent in plots that were exposed to rainwater and showed a low evaporation rate. Patches most exposed to rainwater were directed upwards, and the lowest evaporation rates occurred on the northern side of the trunks.
Conclusions: For many crustose lichens the association with old oak trees seems at least partly to depend on their preference for the deep bark crevices that only occur on old trees. Trees represent epiphyte habitat patches that differ in size due to within-tree variability in habitat quality, such as bark crevice depth and microclimate. This study shows that variability at a finer scale, within habitat patches, contribute to explain species occurrence patterns at habitat patch level
Biochemical characterization of the Arctic char (<it>Salvelinus alpinus</it>) ovarian progestin membrane receptor
<p>Abstract</p> <p>Membrane progestin receptors are involved in oocyte maturation in teleosts. However, the maturation-inducing steroid (MIS) does not appear to be conserved among species and several progestins may fulfill this function. So far, complete biochemical characterization has only been performed on a few species. In the present study we have characterized the membrane progestin receptor in Arctic char (Salvelinus alpinu<it>s</it>) and show that the 17,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P) receptor also binds several xenobiotics, thus rendering oocyte maturation sensitive to environmental pollutants. We identified a single class of high affinity (K<sub>d</sub>, 13.8 ± 1.1 nM), low capacity (B<sub>max</sub>, 1.6 ± 0.6 pmol/g ovary) binding sites by saturation and Scatchard analyses. Receptor binding displayed rapid association and dissociation kinetics typical of steroid membrane receptors, with t<sub>1/2 </sub>s of less than 1 minute. The 17,20beta-P binding also displayed tissue specificity with high, saturable, and specific 17,20beta-P binding detected in ovaries, heart and gills while no specific binding was observed in muscle, brain or liver. Changes in 17,20beta-P binding during oocyte maturation were consistent with its identity as the oocyte MIS membrane receptor. Incubation of fully-grown ovarian follicles with gonadotropin induced oocyte maturation, which was accompanied by a five-fold increase in 17,20beta-P receptor binding. In addition, competition studies with a variety of steroids revealed that receptor binding is highly specific for 17,20beta-P, the likely maturation-inducing steroid (MIS) in Arctic char. The relative-binding affinities of all the other progestogens and steroids tested were less than 5% of that of 17,20beta-P for the receptor. Several ortho, para derivatives of DDT also showed weak binding affinity for the 17,20beta-P receptor supporting the hypothesis that xenobiotics may bind steroid receptors on the oocyte's surface and might thereby interfere with oocyte growth and maturation.</p
17beta-estradiol induced vitellogenesis is inhibited by cortisol at the post-transcriptional level in Arctic char (Salvelinus alpinus)
This study was performed to investigate stress effects on the synthesis of egg yolk precursor, vitellogenin (Vtg) in Arctic char (Salvelinus alpinus). In particular the effect of cortisol (F) was determined since this stress hormone has been suggested to interfere with vitellogenesis and is upregulated during sexual maturation in teleosts. Arctic char Vtg was purified and polyclonal antibodies were produced in order to develop tools to study regulation of vitellogenesis. The Vtg antibodies were used to develop an enzyme-linked immunosorbent assay. The corresponding Vtg cDNA was cloned from a hepatic cDNA library in order to obtain DNA probes to measure Vtg mRNA expression. Analysis of plasma from juvenile Arctic char, of both sexes, exposed to different steroids showed that production of Vtg was induced in a dose dependent fashion by 17ÎČ-estradiol (E2), estrone and estriol. Apart from estrogens a high dose of F also upregulated Vtg. In addition, F, progesterone (P) and tamoxifen were tested to determine these compounds ability to modulate E2 induced Vtg synthesis at both the mRNA and protein level. Tamoxifen was found to inhibit E2 induced Vtg mRNA and protein upregulation. P did not alter the Vtg induction while F reduced the Vtg protein levels without affecting the Vtg mRNA levels. Furthermore the inhibition of Vtg protein was found to be dose dependent. Thus, the inhibitory effect of F on Vtg appears to be mediated at the post-transcriptional level
Nonionic Hydrophilic Surfaces: Adsorption and Interactions
An overview is given of recent studies of nonionic, hydrophilic surfaces formed by the adsorption of surfactants or surface active polymers. Hydrophobic surfaces can be easily hydrophilized by the adsorption of nonionic surfactants or block copolymers containing hydrophobic chain segments; the cooperative interaction between the hydrocarbon moieties contributes more to the free energy of adsorption than the interaction with the hydro- phobic surface.
Hydrophilic layers are also readily formed on hydrophilic surfaces provided specific interaction between the hydrophilic end groups and the surface creates a sufficiently hydrophobic surface so that a second layer can be formed through cooperative interaction. The temperature dependence of the interaction forces between layers of surfactants can be closely correlated with their phase equilibria with water.
In order to prevent protein adsorption the surface should be neither charged nor hydrophobic; it is shown that, accordingly, protein adsorption is extremely low on polyethylene oxide-covered surfaces
Mining for culture : performance arts center StĂ€llbergâs Mine
This degree project summarizes five years of education at the landscape architecture program at the Swedish University of Agriculture Sciences, SLU, Alnarp and the School of architecture at Royal Institute of Technology, KTH, Stockholm. The project has been carried out by Lovisa
Berg and Per Crona in collaboration with DRIFT Scenkonst. This master project is based on the ongoing transformation of a former mining site in StÀllberg, Bergslagen situated in central Sweden.
The organization DRIFT is in the process of recreating to former industrial mining site as a green cultural center. Their field of artistic examination concerns existential questions connected to the site. The aim is to offer a place for both performing and experiencing contemporary performing arts in Bergslagen.
Our objective is to contribute to the growth of the performing arts project and to demonstrate in concrete terms how a conversion of a mining area can be completed, while taking into account both its history and its new function. Theoretical studies of cultural heritage connected to economic and cultural development has been studied on a general level. This has then been related to
site-specific studies and analysis of StÀllberg. The site descriptions and analyzes are of great importance in the project. These account for the historical and cultural context of the site and examine the spatial and architectural conditions and possibilities for the site.
The activities that DRIFT is planning are focused on artistic work and public events and exhibitions,
collectively called âthe Non Existent Centerâ. The two main categories of site users, those working and those visiting have different demands that are important to meet. An important part of the design is to solve problems of accessibility and site utility. It is important to work with forms and structures that reflect new functions while simultaneously telling of the siteâs rich history. The
physical transformation will mainly be carried out by volunteers and design must therefore take into account the expected skill level and knowledge base of this group. In designing this site it is important to address questions of how the center can grow and meet its surrounding landscape.
This project ends with a discussion of the addressed questions and the resulting design proposal.
The working process and the combination of academic methodology and design practice are discussed in a reflective section. The collaboration with DRIFT Scenkonst is also discussed, as is their reaction to our theoretical study and design proposal. At the closure, we describe the future of the Non Existent Center and the part we have played in its transformation.Detta Àr ett examensarbete som avslutar fem Ärs utbildning pÄ landskapsarkitektprogrammet pÄ SLU i Alnarp och KTH Arkitekturskolan i Stockholm. Arbetet har gjorts av Lovisa Berg och Per Crona i samverkan med DRIFT Scenkonst. Arbetet tar sin utgÄngspunkt i den pÄgÄende omvandlingen av StÀllbergs gruva i Bergslagen, Sverige. Organisationen DRIFT scenkonst planerar för en omstÀllning av en nedlagd gruvmiljö till en grön kulturindustri för skapande och
upplevelse av samtidskonst med fokus pÄ existentiella frÄgor knutna till platsen.
MÄlet har varit att bidra till genomförandet av scenkonstprojektet genom ett konkret gestaltningsförslag med grund i den industrihistoriska miljön och den nya funktionen. Teoretiska studier kring kulturarv med koppling till ekonomisk och kulturell utveckling har relaterats till lokala förhÄllanden. Den platsspecifika undersökningen Àr en viktig del av arbetet och beskriver platsens
historiska och kulturella kontext samt analyserar gruvomrÄdets rumsliga och arkitektoniska förutsÀttningar och möjligheter.
Den planerade verksamheten: the Non Existent Center, Àr inriktad pÄ platsspecifikt konstnÀrligt arbete samt publika förestÀllningar och arrangemang. De tvÄ mÄlgrupperna, arbetare och besökare, stÀller olika krav pÄ gestaltningen som Àr viktiga att försöka tillgodose. En viktig del i
gestaltningen Àr att lösa tillgÀngligheten och anvÀndbarheten av omrÄdet. Det Àr ocksÄ viktigt att
formmÀssigt göra ett förslag som speglar sin samtid i relation till den historiska miljön. Den fysiska
omvandlingen ska vara möjlig att genomföra för ideellt verkande krafter och tankar om hur denna omvandling kan ske över tid Àr central.
Arbetet avslutas med en diskussion som behandlar frÄgestÀllningarna och resultatet i gestaltningsarbetet. I en reflekterande del utvÀrderas arbetsprocessen och kombinationen av akademisk metodik och praktiskt gestaltningsarbete. Samarbetet med DRIFT scenkonst behandlas
ocksÄ liksom deras reaktion pÄ studie och gestaltningsförslag. En beskrivning av den fortsatta
arbetsprocessen med the Non Existent Center avslutar arbetet
Associations of parental age with health and social factors in adult offspring. Methodological pitfalls and possibilities
Parental age is increasing rapidly in many countries. Analysis of this potentially important influence on offspring well-being is hampered by strong secular trends and socioeconomic patterning and by a shortage of follow-up data for adult offspring. We used Swedish national data on up to 3,653,938 offspring to consider the associations of parental age with a suite of outcomes in adult offspring, comparing the results from an array of statistical methods for optimal causal inference. The offspring of older mothers had higher BMI, blood pressure, height, intelligence, non-cognitive ability and socioeconomic position. They were less likely to smoke or to be left-handed. Associations with paternal age were strongly, but not completely, attenuated by adjustment for maternal age. Estimates from the commonly-used sibling comparison method were driven primarily by a pathway mediated by offspring date of birth when outcomes showed strong secular trends. These results suggest that the intra-uterine and early life environments provided by older mothers may be detrimental to offspring cardiovascular health, but that their greater life experience and social position may bring intellectual and social advantages to their offspring. The analysis of parental age presents particular challenges, and further methodological developments are needed
Characterization of antibodies for quantitative determination of spiggin protein levels in male and female three-spined stickleback (Gasterosteus aculeatus)
Spiggin is an adhesive glycoprotein produced in the kidney of sticklebacks during the breeding season and is subsequently secreted into the urinary bladder from where it is employed for nest building. Since the production of the protein has been shown to be under androgenic control, spiggin has been suggested to be a useful biomarker for androgenic substances in the environment. In this study, two polyclonal spiggin antibodies based on synthetic peptides and one polyclonal antibody directed against native spiggin have been characterized. The antibodies ability to identify spiggin was investigated by quantitative immunoassay. For both peptide antibodies the quantification range was determined to be between 1 and 80 ng spiggin and determination of renal spiggin levels from immature and mature males displayed a 15-fold increase in total spiggin content of the kidney resulting in a 6-fold increase in male kidney weight due to hypertrophy. The kidney somatic index (KSI) was found to correlate well with the total renal spiggin content and therefore it appears that KSI in sticklebacks could be used as an initial method to identify substances displaying androgenic effects. Furthermore, western blot analysis revealed that the polyclonal antibodies recognize different spiggin isoforms and that spiggin can be detected in the urinary bladder and kidney of both males and female sticklebacks. In order to develop a quantitative detection method for native spiggin it is necessary to produce a standard that can be used in a bioassay. Due to the adhesive and polymerization characteristics of spiggin the protein is difficult to use as a standard in bioassays. So far spiggin has been shown to exist in at least 14 isoforms, all of which contain polymerization domains. To overcome the solubility problem we have produced recombinant spiggin gamma, with only one polymerization domain, that can be expressed in E. coli. Western blot analysis demonstrated that the polyclonal antibodies were able to detect recombinant spiggin gamma protein in bacterial cell lysate, suggesting that it may be developed into a useful source of standard spiggin to be used for quantitative determination of androgen induced spiggin production in sticklebacks
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