576 research outputs found
Epiphyte metapopulation dynamics are explained by species traits, connectivity, and patch dynamics
The colonization-extinction dynamics of many species are affected by the dynamics of their patches. For increasing our understanding of the metapopulation dynamics of sessile species confined to dynamic patches, we fitted a Bayesian incidence function model extended for dynamic landscapes to snapshot data on five epiphytic lichens among 2083 mapped oaks (dynamic patches). We estimate the age at which trees become suitable patches for different species, which defines their niche breadth (number of suitable trees). We show that the colonization rates were generally low, but increased with increasing connectivity in accordance with metapopulation theory. The rates were related to species traits, and we show, for the first time, that they are higher for species with wide niches and small dispersal propagules than for species with narrow niches or large propagules. We also show frequent long-distance dispersal in epiphytes by quantifying the relative importance of local dispersal and background deposition of dispersal propagules. Local stochastic extinctions from intact trees were negligible in all study species, and thus, the extinction rate is set by the rate of patch destruction (tree fall). These findings mean that epiphyte metapopulations may have slow colonization-extinction dynamics that are explained by connectivity, species traits, and patch dynamics
Utomhusbruk. Produkter formgivna för utomhusvistelser
My thesis was based on studying what really happens when Swedes move their beloved kitchen outdoors.?What kind of problems and
possibilities appears in this enviroment? First, I unbiassed examined the traditional kitchen in general to get a better view of how an outdoor
kitchen could function in a country that have diffrent seasons. I intervjued an interior designer specialized in kitchenplanning to get a
better view. One thing that came up was that the experince of beeing outdoor sometimes puts functionality aside. I located different needs in
the outdoor kitchen enviroment and decided to work futher with one of them, outdoor lightning.
The result became a 3d digital model of an outdoor lamp that creates both functionallight and moodlight. The purpose with the lamp was
to create a product designed for the outdoor kitchen work enviroment and to give a moodlight when the kitchen isnÂŽt used. My method was to start with analysing a scenario without knowing
what kind of product that it would result in and this has been a good and openminded process that have led me to identifying several diffrent
needs and problems with the outdoor kitchen
Relative importance of habitat characteristics at multiple spatial scales for wood-dependent beetles in boreal forest
Species distributions are influenced by habitat conditions and ecological processes at multiple spatial scales. An understanding of the importance of habitat characteristics at different spatial scales is important when developing biodiversity conservation measures.We investigated the effect of habitat characteristics or amount at three spatial scales on the occurrence of saproxylic (=dead wood-dependent) beetles.Saproxylic beetles were sampled under the bark of dead wood in a managed forest landscape in central Sweden. We modelled the occurrence probability in dead wood items of 44 species (all species occurring in > 2 % of the items), based on dead wood item characteristics, forest stand characteristics, and habitat connectivity (i.e. area of potentially suitable forest stands in the surrounding of each stand), using hierarchical Bayesian regression.For the majority of species, dead wood item characteristics (especially tree species and whether standing or downed) were more important than measured stand characteristics and habitat connectivity. Whether the stands were clear-cuts, mature forests, or reserves affected some species, whereas the stand-level amount of dead wood per hectare was not important for any species. Habitat connectivity improved the occurrence models for about a half of the species, but there were both positive and negative relationships, and they were generally weak.Forest management should include creation and retention of a high diversity of dead wood to sustain habitat for all species. In a forest-dominated landscape, the spatial distribution of dead wood is of little importance for common saproxylic beetle species
Konsten att lyckas i tidningspappersindustrin
EfterfrĂ„gan pĂ„ tidningspapper har varit vikande pĂ„ nordamerikanska marknaden sedan början pĂ„ 2000-talet. Mellan Ă„ren 2000 till 2010 minskade Ă„rskonsumtionen med över 63 % frĂ„n 13,5 miljoner ton till cirka 5 miljoner ton. Ăven den europeiska marknaden ser ut att gĂ„ en liknande utveckling till mötes och konsumtionen pĂ„ denna marknad började minska allt kraftigare Ă„r 2008.
Denna studie syftar till att via en fallstudie av den nordamerikanska tidningspappersbranschen undersöka vilka konkurrensstrategier som valts och hur lyckosamma de studerade företagen varit i sina val. Förhoppningen med att studera den nordamerikanska marknaden har varit att kunna dra slutsatser om Àven andra marknader. Detta eftersom till exempel den europeiska marknaden ser ut att stÄ inför samma omdaning som den nordamerikanska.
Studien har begrÀnsats till att omfatta tre företag vilka hade ett gemensamt innehav av över 50 % av de nordamerikanska tidningspappersfabrikerna under 2005. De tre valda företagen Àr Resolute Forest Products, Catalyst Paper Corporation och Tembec Inc.
Via studier av teorier vilka Àr lÀmpliga i nedÄtgÄende branscher och studier av karakteristik för tidningspappersbranschen har vi kunnat identifiera tre lÀmpliga strategier för företag i denna bransch. De tre strategierna Àr bÀrgning, nisch och snabb avveckling. Mer precist menas med strategin bÀrgning att företaget vÀljer att maximera kassaflödet frÄn de tillgÄngar de har samtidigt som produktionsenheter med för höga kostnader lÀggs ned. En bÀrgarstrategi kan anvÀndas i en skyddad nisch eller i marknaden som helhet. Ett annat alternativ kan vara att avveckla sÄ snabbt som uttrÀdesbarriÀrerna tillÄter. Detta Àr lÀmpligt dÄ företaget ej har en stark konkurrensposition i nedgÄngens inledning.
Resolute, Catalyst och Tembec Àr företag verksamma inom den nordamerikanska tidningspappersbranschen. De har alla tre försökt tackla nedÄngen pÄ olika sÀtt med varierande resultat. Resolute har satsat pÄ marknadsdominans och bÀrgning och har inte uppnÄtt positivt rörelseresultat förrÀn 2011. De andra tvÄ har ocksÄ satsat pÄ bÀrgning dock inte i en marknadsledande position. Catalyst har de senaste tvÄ Ären visat stora försluter och Tembec har de senaste tvÄ Ären visat pÄ en marginell vinst
Assessing ocean ensemble drift predictions by comparison with observed oil slicks
Geophysical models are cornerstone pieces in marine forecasting of floating
objects and pollution, such as marine surface oil slicks. Trajectory forecasts of oil
spills inherit the uncertainties from the underlying geophysical forcing. In this
work we compare the forecast capabilities of an ocean ensemble prediction
system (EPS) to those from a higher resolution deterministic model on the
representation of oil slick drift. As reference, we use produced water (PW)
slicks detected and delineated from 41 Câband Sentinel-1A/B satellite
synthetic aperture radar images between April and December, 2021. We found
that the EPS provided at least equivalent member-wise results relative to
simulations forced with the deterministic model. Ensemble verification through
rank histograms and spread-error relationship showed that including the ocean
fields is necessary to address model uncertainties. Whether considering the
ocean field or not, the modeled slicks were counterclockwise rotated between
20° and 30° relative to the ones observed in the satellite images, and these were
deflected about 45° to the right of the observed wind direction
Demonstrating the Performance and Emission Characteristics of a Variable Compression Ratio, Alvar-Cycle Engine
This paper is a direct continuation of a previous study that addressed the performance and design of a variable compression engine, the Alvar-Cycle Engine [1]. The earlier study was presented at the SAE International Conference and Exposition in Detroit during February 23- 26, 1998 as SAE paper 981027. In the present paper test results from a single cylinder prototype are reviewed and compared with a similar conventional engine. Efficiency and emissions are shown as function of speed, load, and compression ratio. The influence of residual gas on knock characteristics is shown. The potential for high power density through heavy supercharging is analyzed
Disturbance interval modulates the starting point for vegetation succession
Increased frequency and new types of disturbances caused by global change calls
for deepened insights into possible alterations of successional pathways. Despite current interest
in disturbance interactions there is a striking lack of studies focusing on the implication of
decreasing times between disturbances. We surveyed forest-floor vegetation (vascular plants
and bryophytes) in a Pinus sylvestrisâdominated, even-aged production forest landscape,
unique because of the presence of stands under a precisely dated disturbance interval gradient,
ranging from 0 to 123 yr between clearcutting and a subsequent megafire. Despite a dominance
of early-successional species in all burned stands 5 yr after fire, progression of succession
was linked to time since the preceding clearcutting disturbance. This was most clearly seen in
increased frequency with time since clearcutting of the dominant, late-successional dwarf
shrub Vaccinium myrtillus, with surviving rhizomes as an important mechanism for postfire
recovery. Our results demonstrate the role of legacy species as significant drivers of succession.
We conclude that the starting point for succession is modulated by disturbance interval, so that
shortened intervals risk reducing development towards late-successional stages. We suggest
that a decrease in long successional sequences caused by more frequent disturbances may represent
a general pattern, relevant also for other forest types and ecosystems
Optimering av bemanning för att möta kundflöde och öka servicen â En jĂ€mförande fallstudie pĂ„ Stadium Helsingborg
Problembeskrivning: I retailbranschen, som Àr en personalintensiv bransch, stÀlls det allt högre krav pÄ servicen i butiken. Om företaget kan förmedla en upplevelse av hög kvalitet genom bra service skapas lojala och nöjda kunder. DÄlig optimering av personal i butiken kan vara kostsamt och ge upphov till dÄlig service. Syfte och FrÄgestÀllningar: Syftet med uppsatsen Àr att belysa vikten av att arbeta med service och koppla detta till optimering av bemanning i butik. FrÄgestÀllningarna blir följande: ⹠Hur arbetar butiker effektivt med bemanning? ⹠Hur leder optimerad butiksbemanning till bÀttre service mot kunderna? Presentation av fallföretaget: Arbetet Àr ett resultat av en fallstudie av Stadiumbutikerna pÄ VÀla och Kullagatan i Helsingborg. AvgrÀnsningar: Vi har avgrÀnsat oss till att endast studera ett företag i en stad. Vi har inte belyst skillnaden av lokaliseringen pÄ de tvÄ butikerna. EnkÀten Àr avgrÀnsad och representerar bara en ögonblicksbild av verksamheten och dess förutsÀttningar. Metod: I arbetet har vi anvÀnt oss av en kombination av kvantitativa enkÀter och kvalitativa intervjuer. Dessa har vi applicerat pÄ Stadium Helsingborg som en jÀmförande fallstudie. Teoretisk ram: Tyngden i den teoretiska ramen ligger pÄ servicemanagement forskning av Grönroos med SERVQUAL och gapanalys med stöd frÄn Normann med serviceföretagens tre goda cirklar. Tidigare forskning: I avsnittet har vi diskuterat orden kundflöde, service och bemanning för butiken. Resultat: Kundnöjdhetsundersökningen resulterade i att kunden tycker servicen spelar en avgörande roll i valet av butik. Vi har Àven identifierat en grupp med kritiska kunder som vi anser man borde arbeta med. Stadium arbetar aktivt med att hantera kundflödet genom deras personalbemanning för att upprÀtthÄlla en hög servicegrad mot kunden. Analys: Stadium har minimala servicegap mellan kundens och ledningens uppfattning, vilket tyder pÄ att Stadium Àr medvetna om deras servicekvalitet. Stadium hanterar De tre goda cirklarna, vilka Àr, sanningens ögonblick, makrocirkeln och den interna servicecirkeln, pÄ ett effektivt och kundvÀnligt sÀtt. Slutsatser & diskussion: Att möta kundens behov Àr viktigt. Det Àr dÀrför viktigt att tÀnka pÄ servicen i butiken och att servicen kan anvÀndas som en stark konkurrensfördel. Om man brister pÄ nÄgon faktor i butiken pÄverkas kundens helhetsintryck och kundens vistelse i butiken kan bli negativ. Det Àr dÀrför viktigt att arbeta med samtliga aspekter sÄsom service, kundflöde samt optimeringen av personal i butiken
A Fully Abstract Symbolic Semantics for Psi-Calculi
We present a symbolic transition system and bisimulation equivalence for
psi-calculi, and show that it is fully abstract with respect to bisimulation
congruence in the non-symbolic semantics.
A psi-calculus is an extension of the pi-calculus with nominal data types for
data structures and for logical assertions representing facts about data. These
can be transmitted between processes and their names can be statically scoped
using the standard pi-calculus mechanism to allow for scope migrations.
Psi-calculi can be more general than other proposed extensions of the
pi-calculus such as the applied pi-calculus, the spi-calculus, the fusion
calculus, or the concurrent constraint pi-calculus.
Symbolic semantics are necessary for an efficient implementation of the
calculus in automated tools exploring state spaces, and the full abstraction
property means the semantics of a process does not change from the original
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