Dendritic Actin Filament Nucleation Causes Traveling Waves and Patches

The polymerization of actin via branching at a cell membrane containing nucleation-promoting factors is simulated using a stochastic-growth methodology. The polymerized-actin distribution displays three types of behavior: a) traveling waves, b) moving patches, and c) random fluctuations. Increasing actin concentration causes a transition from patches to waves. The waves and patches move by a treadmilling mechanism which does not require myosin II. The effects of downregulation of key proteins on actin wave behavior are evaluated.Comment: 10 pages, 4 figure

Utvärdering och analys av drivningsentreprenörer utifrån offentlig ekonomisk information

Representanter för drivningsentreprenörerna i Sverige har länge påtalat en sviktande lönsamhet för drivningsentreprenörerna. Denna studie söker svar på hur de stora köparna av drivningstjänster arbetar med analys och värdering av sina sysselsatta drivningsentreprenörer. Studien fokuserar på den information som kan inhämtas från offentlig finansiell information. Studien omfattar tio av de största köparna av drivningstjänster i Sverige. Dessa har genom en kvalitativ ansats intervjuats i ämnet. För att åskådliggöra de tillvägagångssätt samt drivningsentreprenörernas ekonomiska status presenteras även en samling nyckeltal baserat på 400-437 drivningsentreprenörer. Studien visar att det råder en stor skillnad i hur de stora köparna av drivningstjänster arbetar med analys och värdering av sina drivningsentreprenörer utifrån offentliga årsredovisningar och nyckeltal. Alla i studien tillfrågade organisationen har tillgång till sina entreprenörers nyckeltal. Dock råder det stora skillnader i hur denna information används. Majoriteten av de tillfrågade drar inga större slutsatser utifrån denna information. En organisation uppvisar en särklass i arbetet med analys och värdering utifrån offentlig ekonomisk information. Denna organisation analyserar årligen samtliga drivningsentreprenörers årsredovisningar och producerar själva sina entreprenörers nyckeltal. Organisationen är också den enda att ha fastställda intervall för olika nyckeltal inom vilka entreprenörerna bör ligga för att vara lönsamma. Unikt för denna organisation är också att de kombinerar produktionsnyckeltal med ekonomiska nyckeltal. Studien visar också att de organisationerna som arbetar mest med analys och bedömning utifrån årsredovisningar hyser en större tilltro till informationen som detta arbete ger. I studien har det framgått att de stora köparna av drivningstjänster väljer att studera följande nyckeltal: Avkastning eget kapital, Avkastning totalt kapital, Rörelsemarginal, Omsättning per anställd, Personalkostnader i relation till omsättning, Soliditet, Kassalikviditet, Förändring av nettoomsättning, Förändring av antal anställda och Vinstmarginal. Det är också dessa nyckeltal som presenteras för de entreprenörer som sysselsätts av de i studien ingående organisationerna. Nyckeltalen från 2007 baseras på 400 företag, nyckeltalen från 2008 baseras på 424 företag och nyckeltalen från 2009 baseras på 437 företag. Att denna siffra varierar beror på att leverantören av nyckeltalen ej haft information från alla företag för alla år samt att ett antal företag inte haft några anställda under vissa år. Studien visar att det krävs justering av årsredovisningen för att ge tillförlitlig information och nyckeltal. Ingen organisation använder sig av någon typ av modell vid analys och bedömning av drivningsentreprenörer. Jag föreslår att DuPont-modellen kan användas som ett verktyg i detta arbete. Modellen är lättöverskådlig och medger simuleringar av olika strategiska beslut som både den enskilda entreprenören och de stora köparna av drivningstjänster kan dra nytta av

Molecular serum portraits - A step towards personalized medicine

Antibody microarray technology has the potential for playing a large roll in identifying serological biomarker panels for personalized medicine. The aim of this thesis, based on four original papers, was to investigate if information in the serum proteome could be extracted and used for diagnostic, classificational, prognostic or treatment predictive purposes in a range of diseases. In two studies (paper I and paper IV), the diagnosis and prognosis of breast cancer was addressed, also being the main focus of this thesis. In paper I, we identified a biomarker panel capable of stratifying serum samples from metastatic breast cancer patients from those of healthy controls. In paper IV, another panel, pre-validated in the same study, was deciphered that could be used to identify patients destined for metastatic disease in a group of newly diagnosed breast cancer patients. Paper II and III targeted immunotherapy of glioblastoma multiforme and the diagnosis and sub- stratification of two autoimmune diseases (SLE and SSc), respectively. Also in these cases, multiple biomarker panels were identified, each capable of separating predefined cohorts of patients with relevance for applications within personalized medicine. In conclusion, this thesis introduces the concept of personalized medicine; details the antibody microarray technology in general and the platform used for the experiments in paper I to IV; and describes the subsequent microarray data analysis

Destroyed quantum Hall effect in graphene with [0001] tilt grain boundaries

The reason why the half-integer quantum Hall effect (QHE) is suppressed in graphene grown by chemical vapor deposition (CVD) is unclear. We propose that it might be connected to extended defects in the material and present results for the quantum Hall effect in graphene with [0001] tilt grain boundaries connecting opposite sides of Hall bar devices. Such grain boundaries contain 5-7 ring complexes that host defect states that hybridize to form bands with varying degree of metallicity depending on grain boundary defect density. In a magnetic field, edge states on opposite sides of the Hall bar can be connected by the defect states along the grain boundary. This destroys Hall resistance quantization and leads to non-zero longitudinal resistance. Anderson disorder can partly recover quantization, where current instead flows along returning paths along the grain boundary depending on defect density in the grain boundary and on disorder strength. Since grain sizes in graphene made by chemical vapor deposition are usually small, this may help explain why the quantum Hall effect is usually poorly developed in devices made of this material.Comment: 5 pages, 4 figure

Expression of mRNA for phospholipase A(2), cyclooxygenases, and lipoxygenases in cultured human umbilical vascular endothelial and smooth muscle cells and in biopsies from umbilical arteries and veins

Arachidonic acid (AA) is released by phospholipase A(2) (PLA(2)) and then converted into vasoactive and inflammatory eicosanoids by cyclooxygenases (COX) and lipoxygenases (LOX). These eicosanoids are important paracrine regulators of vascular permeability, blood flow, local pro- and anticoagulant activity and they play a major role in the local inflammatory response. We have investigated the presence of mRNAs for PLA(2) and for isoforms of COX and LOX in both human endothelial cells (EC) and in human smooth muscle cells (SMC) in culture and in vascular biopsies of human umbilical veins (HUVB) and arteries (HUAB) by using the reversed transcription-polymerase chain reaction (RT-PCR) technique. Results show detectable levels of PLA(2) type IV (cPLA(2)) in cultured EC and SMC and in vascular wall biopsies from HUAB and HUVB. The cultured EC and SMC demonstrate higher levels of both COX-1 and COX-2 with PCR analyses than do vascular wall biopsies from HUAB and HUVB. This indicates a difference in the native expression of COX-1 and COX-2 in cultures of EC and SMC compared to that in biopsies from intact vessel walls. The EC and SMC in culture do not express mRNA for 5-LOX, that was, however, expressed in the vascular wall biopsies. This speaks in favour of a constitutive, i.e, in vivo expression of 5-LOX in SMC in the vascular wall of both umbilical vein and arteries. Thus results from in vitro studies of constitutive COX and LOX expression in EC and vascular SMC in culture cannot simply be extrapolated to represent in vivo conditions

Valorisation of 2,5-dimethylfuran over zeolite catalysts studied by on-line FTIR-MS gas phase analysis

The valorisation of 2,5-dimethylfuran (2,5-dmf) by catalytic fast pyrolysis (CFP) was studied by on-line FTIR-MS gas phase analysis. Zeolite beta, H-ZSM-5 and Cu-ZSM-5 were characterised and used as catalysts. The on-line analysis enables sufficient time resolution to follow subminute transient phenomena, e.g., the impact of catalyst pretreatment and time on stream (TOS) on the reaction selectivity. The results show, that the initial selectivity towards benzene, toluene and xylene (BTX) aromatics is high but decreases with TOS while the isomerisation rates of 2,5-dmf towards 2,4-dimethylfuran and cyclic ketones increase. This indicates the involvement of specific active sites for the different conversion processes. The formation of BTX compounds is linked to the availability of specific olefins, as supported by temperature programmed desorption experiments, which is indicative of aromatisation stemming directly from the olefin pool rather than via Diels-Alder reactions

On-Line Composition Analysis of Complex Hydrocarbon Streams by Time-Resolved Fourier Transform Infrared Spectroscopy and Ion− Molecule Reaction Mass Spectrometry

On-line composition analysis of complex hydrocarbon\ua0mixtures is highly desirable to determine the composition of process streams\ua0and to study chemical reactions in heterogeneous catalysis. Here, we show\ua0how the combination of time-resolved Fourier transform infrared spectroscopy and ion−molecule-reaction mass spectrometry (IMR-MS) can be used\ua0for compositional analysis of processed plant biomass streams. The method is\ua0based on the biomass-derived model compound 2,5-dimethylfuran and its\ua0potential catalytic conversion to valuable green aromatics, for example,\ua0benzene, toluene, and ylenes (BTX) over zeolite β. Numerous conversion\ua0products can be determined and quantified simultaneously in a temporal\ua0resolution of 4 min−1 without separation of individual compounds. The\ua0realization of this method enables us to study activity, selectivity, and changes in composition under transient reaction conditions. For example, increasing isomerization of 2,5-dimethylfuran to 2,4-dimethylfuran, 2-methyl-2-cyclopenten-1-one, and 2-methyl-2-cyclopenten-1-one is observed as the catalyst is exposed to the reactant, while BTX and olefin formation is decreasing

A transient in situ infrared spectroscopy study on methane oxidation over supported Pt catalysts

Catalysts with platinum dispersed on alumina, ceria and mixed alumina-ceria have been prepared by incipient wetness impreg- nation, characterized with transmission electron microscopy and X-ray diffraction, and evaluated for total oxidation of methane under both stationary and transient gas compositions (oxygen pulsing). Further, in situ diffuse reflectance Fourier transformed infrared spectroscopy has been used to monitor the evolution of surface species during precise transient gas composition changes using high-speed gas switching valves. The results show that platinum interacts sufficiently strong with all the supports so as to form small platinum particles. The smallest sizes are observed for the Pt/Ce sample. The alumina con- taining samples show, in contrast to the Pt/Ce sample, a decreased methane conversion with the increasing oxygen concentration and a clear kinetic bistability between increasing and decreasing oxygen concentrations. The bistable kinetics is likely connected to oxidation and reduction of platinum occurring at different stoichiometric gas mixtures depending on the history of the system, for which an oxidation of the platinum particles effectively inhibits the dissociative adsorption of methane leading to low reaction rate. It is shown for the alumina containing samples that the adverse effects of oxygen excess can be circumvented by the use of periodic operation so that the the average methane conversion is improved. Further, Pt/Ce seems to exhibit additional active sites at the platinum-ceria interface explaining the generally higher conversion of methane for this sample