Technical Note: Evaporation of polar stratospheric cloud particles, in situ, in a heated inlet

International audienceIn December 2001 and 2002 in situ aerosol measurements were made from balloon-borne platforms within polar stratospheric clouds (PSC) which contained particles of supercooled ternary solution (STS), nitric acid trihydrate (NAT) and ice. Particle size and number concentrations were measured with two optical particle counters. One of these included an ~80cm inlet heated to K to evaporate the PSC particles and thus to obtain measurements, within PSCs, of the size distribution of the particles upon which the PSCs condensed. These measurements are compared to models, described here, that calculate the evaporation of PSC particles at and for an inlet transition time of about 0.1s. The modeled evaporation for STS agrees well with the measurements. For NAT the modeled evaporation is less than the evaporation measured. The primary uncertainty concerns the phase and morphology of NAT particles as they are brought to temperatures >50K above equilibrium temperatures for NAT at stratospheric partial pressures. The slow evaporation of NAT in heated inlets could be used to identify a small NAT component within a mixed phase PSC dominated by STS

MR determined brain metabolic pattern in patients with brain metastases and adolescents with low birth weight

The clinical applications of MRS have become a supplement to MR imaging (MRI) for diagnosis and treatment monitoring of several pathologies. In this thesis MR spectroscopy (MRS) has been used to assess brain metastases in adult cancer patients and cerebral metabolites in frontal lobe of adolescents. Children born with very low birth weight are at risk of later neurodevelopment problems. Adolescents with different birth weight were examined using MRI and MRS and multivariate analyses for assessing differences in cerebral metabolites. The results from the multivariate analyses were consistent with observations in earlier published MRI findings, motor skills, psychiatric symptoms and disorders detected in the same participants. The classification of the adolescents was based on metabolic pattern differences which were only explored by the multivariate analyses. When the spectral information shows small or complex differences the interpretations become a challenge. In three of the four papers in this thesis, multivariate analyses were used as a tool to interpret the spectral information. Brain metastasis is the dominating type of brain tumors which represent an oncologic challenge. The incidence of brain metastases is probably increasing due to improved treatment strategy of patient with primary cancer, prolonging their survival and brain metastases get time to develop. In some cases patients have an unknown primary cancer or several primary cancers. If MRS could provide metabolic information about brain metastases especially in differentiating it from the primary cancer, it might be a supplement to the conventional diagnostics and could help to optimize the cancer treatment. In the two last papers in vivo and ex vivo MRS of brain metastases were obtained before treatment and the spectra were analysed by using both principal component analysis and regression analysis. The spectra were classified according to primary cancer and clinical outcome five months after start of treatment. The results showed a significant correlation of spectral findings and clinical outcome of brain metastases patients. From the MR theory, signal-to-noise ratio and resolution in MR spectra should increase by a factor of two with double the magnetic field strength. Different studies using in vivo MRS have shown that the situation varies. In Paper II the effect of increased magnetic field from 1.5T to 3T was investigated in spectra obtained in patients with brain metastases. The comparisons of spectral improvements in SNR and spectral resolution were made by ratio calculations. The gain was smaller than expected probably caused by various definitions of effective volume size at different clinical scanners. In conclusion, in vivo and ex vivo MR spectroscopy can determine metabolic pattern on clinically highly relevant questions.PhD i medisinsk teknologiPhD in Medical Technolog

β-(1,3)-glucan-b-chitosan and β-(1,3)-glucan-b-biotin diblocks: Preparation, purification, and characterisation

Målet med denne masteroppgaven var å forberede SBG-b-kitosan og SBG-b-biotin diblokker, inkludert fremstilling og rensing av SBG-oligomerer. Polysac- karider kommer fra naturlig rssurser og er ikke-giftige, biokompatible og svært interessante innenfor medisinske applikasjoner. På grunnlag av deres bioaktivitet og immunol- ogiske interaksjoner, er preparering av blokkpolysakkarider av SBG, kitosan og biotin var av stor interesse. Målet med den første delen av oppgaven var å bryte ned lavmolekylære løselige β-(1,3)-glukaner (SBG) gjennom syrehydrolyse, for å oppnå oligomerer med en grad av polymerisering (DP), dvs. kjedelengde, mellom 1 og 25. En betydelig hindring ved fremstilling av diblokker er den høye konsentrasjonen av salt som følge av ned- brytning og bruk av bufferløsning. I dette studie ble dialyse, en veletablert renseteknikk, sammenlignet med en nylig introdusert sentrifugerings teknikk med brukt av filter i et forsøk på å potensielt redusere rensetiden og øke mengden bevart masse. Resul- tatene viste imidlertid at filteret ikke klarte å bevare SBG-oligomerene og ble ansett som ineffektiv i separering av SBG oligomerer fra de mindre urenhetene. I den andre delen av masteren ble det fremstilt SBG-b-chitosan diblokker og startet med terminal aktivering av SBG med linkermolekylet O,O’-1,3-propandiylbishydroksylamin (PDHA). En sammenligning ble gjort mellom aktiveringen av en ikke-renset løs-ning av hydrolysert SBG og en renset (dialysert) løsning av hydrolysert SBG, for å bestemme om den høye konsentrasjonen av Na2SO4 i hydrolysatet påvirker reak- sjonskinetikken. Ved å bruke time course 1H-NMR, konkluderes det med at reak- sjonshastigheten mellom de to er neglisjerbar, hvor begge resul0tere i et relativt høyt utbytte på ∼85%. Basert på denne analysen er dermed rensing av SBG-hydrolysat før fremstilling av SBGm -PDHA ikke ansett som nødvendig, noe som reduserer antallet trinn hvor produktet kan gå tapt. Et høyt utbytte på konjugering av SBGm-b-kitosan ble raskt oppnått, med en verdi på > 90% etter bare 30 minutter. I den siste delen av ble forskjellige SBG-b-biotin-diblokker fremstilt og sammenlignet, for å vurdere overførbarheten av den preparative protokollen mellom SBG- b-biotin diblokker av ulik kjedelengde. Resultatet viste at alle de tre ulike kjedelengdene av SBGm (4 < DP < 20) oppnådde omtrent samme likevektsutbytte på 60%. Ved å øke den molare ekvivalenten fra 2x til 4x mellom SBGm og Biotin-PEG3 økte reaksjonshastigheten, men utbyttet lå fortsatt på det samme. Derfor er yt- terligere forskning nødvendig for å optimalisere den preparative protokollen når det gjelder konjugasjonsutbytte.The main goal of this master’s thesis was to prepare SBG-b-chitosan and SBG-b- biotin diblocks, including the preparation and purification of SBG oligomers. Polysac- charides come from natural resources and are non-toxic, biocompatible and highly interesting in the field of medical applications. Due to their bioactivity and im- munological interactions, preparing block polysaccharides from SBG, chitosan, and biotin was of great interest. The objective of the first section of this thesis was to degrade low-molecular soluble β-(1,3)-glucans (SBG) by acid hydrolysis in order to obtain oligomers with a degree of polymerisation (DP), i.e chain length, between 1 and 25. A significant obstacle in the preparation of diblocks is the high concentration of salt resulting from degrada- tion and the utilization of buffer solution. In this study, dialysis, a well-established purification technique, was compared to a recently introduced centrifugal filtra- tion technique in an effort to potentially reduce purification time and increase the amount of mass preserved. However, the results demonstrated that the centrifugal filter failed to preserve the SBG oligomers and was therefore deemed ineffective for separating SBG from minor impurities. In the second part of the thesis, SBG-b-chitosan diblocks were prepared, starting with terminal activation of SBG with the linker molecule O,O’-1,3-propanediylbishydroxylamine (PDHA). A comparison was made between the activation of a non-purified solution of hydrolysed SBG and a purified (dial- ysed) solution of hydrolysed SBG to determine if the high concentration of Na2SO4 in the hydrolysate affects reaction kinetics. Using time-course 1H-NMR, the reac- tion rate between the two is concluded to be neglected, both resulting in a relatively high yield of ∼ 85%. Thus, purification of SBG hydrolysate prior to preparation of SBGm-PDHA is, based on this analysis is not necessary, reducing the number of steps in which product can be lost. Following, conjugation of SBGm-b-chitosan was quickly obtained, with a yield of > 90% after only 30 minutes. In the final part of this thesis, different SBG-b-biotin diblocks were prepared and compared to assess the transferability of the preparative protocol between SBG-b-biotin diblocks of different chain lengths. The result showed that all tree chain lengths of SBGm (4 < DP < 20) obtained approximately the same combined equi- librium yield of 60%. By increasing the molar equivalent from 2x to 4x between SBGm and Biotin-PEG3 the reaction rate increased, but the combined yield was un- changed. Therefore, additional research is necessary to optimize the preparative protocol in terms of conjugation yield

Ice Initiation by Aerosol Particles: Measured and Predicted Ice Nuclei Concentrations versus Measured Ice Crystal Concentrations in an Orographic Wave Cloud

The initiation of ice in an isolated orographic wave cloud was compared with expectations based on ice nucleating aerosol concentrations and with predictions from new ice nucleation parameterizations applied in a cloud parcel model. Measurements of ice crystal number concentrations were found to be in good agreement both with measured number concentrations of ice nuclei feeding the clouds and with ice nuclei number concentrations determined from the residual nuclei of cloud particles collected by a counterflow virtual impactor. Using lognormal distributions fitted to measured aerosol size distributions and measured aerosol chemical compositions, ice nuclei and ice crystal concentrations in the wave cloud were reasonably well predicted in a 1D parcel model framework. Two different empirical parameterizations were used in the parcel model: a parameterization based on aerosol chemical type and surface area and a parameterization that links ice nuclei number concentrations to the number concentrations of particles with diameters larger than 0.5 μm. This study shows that aerosol size distribution and composition measurements can be used to constrain ice initiation by primary nucleation in models. The data and model results also suggest the likelihood that the dust particle mode of the aerosol size distribution controls the number concentrations of the heterogeneous ice nuclei, at least for the lower temperatures examined in this case

Assessment of Biomass Burning Smoke Influence on Environmental Conditions for Multi-Year Tornado Outbreaks by Combining Aerosol-Aware Microphysics and Fire Emission Constraints

We use the WRF system to study the impacts of biomass burning smoke from Central America on several tornado outbreaks occurring in the US during spring. The model is configured with an aerosol-aware microphysics parameterization capable of resolving aerosol-cloud-radiation interactions in a cost-efficient way for numerical weather prediction (NWP) applications. Primary aerosol emissions are included and smoke emissions are constrained using an inverse modeling technique and satellite-based AOD observations. Simulations turning on and off fire emissions reveal smoke presence in all tornado outbreaks being studied and show an increase in aerosol number concentrations due to smoke. However, the likelihood of occurrence and intensification of tornadoes is higher due to smoke only in cases where cloud droplet number concentration in low level clouds increases considerably in a way that modifies the environmental conditions where the tornadoes are formed (shallower cloud bases and higher low-level wind shear). Smoke absorption and vertical extent also play a role, with smoke absorption at cloud-level tending to burn-off clouds and smoke absorption above clouds resulting in an increased capping inversion. Comparing these and WRF-Chem simulations configured with a more complex representation of aerosol size and composition and different optical properties, microphysics and activation schemes, we find similarities in terms of the simulated aerosol optical depths and aerosol impacts on near-storm environments. This provides reliability on the aerosol-aware microphysics scheme as a less computationally expensive alternative to WRFChem for its use in applications such as NWP and cloud-resolving simulations

Sustainability analysis of the CITYLAB solutions

The objective of the CITYLAB project is to develop knowledge and solutions that result in roll-out, upscaling and further uptake of cost effective strategies, measures and tools for emission free city logistics. CITYLAB includes a set of Living Laboratories where promising logistic concepts are implemented related to emissions free city logistics. The objective of this report is to assess the impact that would occur when the CITYLAB implementations would be scaled up. The main challenge that has to be overcome is the difference in type, availability and detail of data from different CITYLAB implementations. This assessment of the impacts of upscaling is done by integrating all stakeholders’ opinions in the evaluation process and taking into account the costs and benefits for society as well as the financial viability for industry partners

Impact and process assessment of the seven CITYLAB implementations

CITYLAB focuses on four axes that call for improvement and intervention: •Highly fragmented last-mile deliveries in city centres •Inefficient deliveries to large freight attractors and public administrations •Urban waste, return trips and recycling •Logistics sprawl Within these axes, the project supports seven implementations that are being tested, evaluated and rolled out. An implementation is defined as the process of preparing, testing and putting into practice a new service or a new way of operating or organising logistics activities. The objective of this report is to present an assessment of the effects and consequences of the implementations as they are conducted. For each case, we summarise the process leading to the application of a specific technical and managerial solution, and present the outcomes. For each implementation, we present •Problem and aim •Description of the solution •Implementation process •Effects and consequences •Challenges ahead •Lessons and generalisation of results This deliverable provides a complete picture of the evolvement of the implementations during the CITYLAB project and final versions of the process and impact assessment

Arbeidsform i tiden etter Covid-19: I hvilken grad påvirker ledere hvorvidt fjernarbeid vil være en god langsiktig arbeidsform i tiden etter Covid-19?

I en to år lang periode har yrkesaktive i stor grad benyttet fjernarbeid som følge av Covid-19. Store bedrifter fremmer fjernarbeid som fremtidens arbeidsform og forskning tyder på at mange ønsker å fortsette med arbeidsformen i tiden etter pandemien. Vi undersøker i denne oppgaven interne forhold som kan være avgjørende for hvorvidt fjernarbeid vil være en god løsning i tiden etter Covid-19. Det økende fokuset på lederens ansvar ovenfor medarbeidere og deres trivsel på jobb de to foregående år, la grunnlaget for de interne forholdene som ble undersøkt i studien. Studiens problemstilling er: «I hvilken grad påvirker ledere hvorvidt fjernarbeid vil være en god langsiktig arbeidsform i tiden etter Covid-19?» To premisser er lagt til grunn for at fjernarbeid skal være en god langsiktig arbeidsform: ønske om fjernarbeid og tilstrekkelig oppfølging av medarbeidere ved fjernarbeid. Det teoretiske rammeverket og tidligere empiri resulterte i fire forskningsspørsmål tilknyttet lederatferd og kommunikasjon i forbindelse med overnevnte premisser. Forskningsspørsmålene er testet empirisk gjennom kvantitativ metode med spørreundersøkelse som måleverktøy. Undersøkelsen er avgrenset til foretaket Sykehusinnkjøp HF (SHI) sine 262 medarbeidere, hvor svarprosenten er 64,6 %. Det kvantitative datagrunnlagets validitet og reliabilitet er testet gjennom faktoranalyse og reliabilitetsanalyse, hvor spørsmål er gruppert og støy er ekskludert fra datasettet. Videre er dataen statistisk analysert og forskningsspørsmålene testet ved hjelp av univariat analyse, korrelasjonsanalyse og multippel regresjonsanalyse. Funnene tilsier at medarbeidere ønsker fjernarbeid i tiden etter Covid-19 og føler seg tilstrekkelig fulgt opp av nærmeste leder ved fjernarbeid. Vi finner at SHI scorer høyt på variabler vi antok ville ha positiv påvirkning og lavt på variabler vi antok ville ha negativ påvirkning på overnevnte premisser. Dette indikerer at fjernarbeid vil være en god langsiktig løsning i tiden etter Covid-19. Basert på analysene finner vi dog ingen god forklaringsfaktor tilknyttet ønske, som betyr at vi ikke kan konkludere med at ønske er tuftet på langsiktig perspektiv. Vi finner derimot at ledere i SHI i stor grad gjennom personlig kommunikasjon påvirker hvorvidt medarbeidere føler seg tilstrekkelig fulgt opp ved fjernarbeid. Lederne i SHI scorer høyt på personlig kommunikasjon, som tilsier at fjernarbeid med hensyn til tilstrekkelig oppfølging vil være en god langsiktig arbeidsform såfremt de opprettholder scoren. Ingen av våre funn tyder på at fjernarbeid vil være en dårlig løsning i SHI. Det solide nettoutvalget medfører at vi anser det mulig å generalisere våre funn til populasjonen