Characterization of mixed allogeneic chimeras. Immunocompetence, in vitro reactivity, and genetic specificity of tolerance.

Mixed allogeneically reconstituted mice (B10 + B10.D2----B10) that specifically accept B10.D2 tail skin allografts were examined for in vivo and in vitro immunocompetence, patterns of hematopoietic repopulation, and in vitro reactivity. In vitro, mixed allogeneic chimeras (B10 + B10.D2----B10) manifested specific tolerance in mixed lymphocyte reactions and cell-mediated lympholysis to B10 and B10.D2 splenocytes, with normal responses to third-party (B10.BR) cells. Such chimeras were immunocompetent in B cell and helper T cell responses, as assessed by their primary plaque forming cell responses to in vivo sheep red blood cell immunization. This is in contrast to fully allogeneic chimeras, which responded less well. In addition, survival of the mixed allogeneic chimeras in a conventional animal facility was superior to that of fully allogeneic chimeras, and similar to syngeneically reconstituted (B10----B10) mice. Specific tolerance to skin grafts, degree of allogeneic engraftment, and persistence of chimerism was also assessed in a noncongenic mixed allogeneic combination (B10 + C3H----B10). Such animals manifested specific hyporeactivity to C3H skin allografts, but eventual chronic rejection of the grafts occurred in spite of stable and persistent mixed chimerism. MHC-congenic (B10.BR) skin grafts were accepted indefinitely in the same animals, suggesting that skin-specific non-major histocompatibility complex antigens were responsible for rejection of the C3H skin allografts

AC Breakdown Voltage of 50-Year-Old Service Aged Hydro Power Generator Stator Bars

Randomly selected generator bars from a 50-year-old Norwegian hydro power generator were examined in this work. Typical non-destructive tests, as partial discharge and dissipation factor measurements were initially performed at both 50 Hz and 0.1 Hz. Then, the AC breakdown strength of the epoxy/mica/glass fibre reinforced bar insulation was measured by gradually increasing the voltage in steps of 5 kV with duration of 1 min until breakdown occurred. The field graded terminations were soaked in transformer oil during breakdown testing to prevent external surface flashovers. The AC breakdown voltage ranged between 60 kV and 75 kV, which corresponds to 8-10-fold the service voltage of 7.4 kV. No significant difference in breakdown voltage was observed between bars being located close to the high voltage or neutral terminal during service. This indicates minor degradation caused by the AC service stress, even after 50 years in service. No correlations were found between the measured breakdown voltage and the diagnostic partial discharge activity and dissipation factor measurements.AC Breakdown Voltage of 50-Year-Old Service Aged Hydro Power Generator Stator BarspublishedVersio

A stochastic model for contact surfaces at polymer interfaces subjected to an electrical field

Morphology of the contact area between solid insulation materials ultimately determines the short- and long-term electrical properties of the complete insulation system. The main purpose of this paper is to propose a statistical model to examine the real area of contact between solid dielectric surfaces and secondly to verify and correlate the model outputs with experiments. The model computes the real area of contact, number of contact spots and average cavity size at the interface as a function of elasticity, contact force, and surface roughness. Then, using the average cavity size and the Paschen's law, the discharge inception field of the cavity (CDIE) is estimated. AC breakdown strength (BDS) testing of solid-solid interfaces was carried out, where cross-linked polyethylene (XLPE) samples with four different surface roughnesses were tested at various contact pressures. Following the increased contact force, the calculated average cavity size decreased by a factor of 4.08-4.82 from the roughest to the smoothest surface, corresponding to increased CDIEs by a factor of 2.01-2.56. Likewise, the experimentally obtained BDS values augmented by a factor of 1.4-1.7 when the contact pressure was elevated from 0.5 MPa to 1.16 MPa. A linear correlation between the CDIE and BDS was assumed, yielding a correlation coefficient varying within 0.8-1.3. When the 90% confidence intervals were considered, the range reduced to 0.86-1.05. This correlation suggests that interfacial breakdown phenomenon is strongly related to the interfacial cavity discharge. Hence, the proposed model is verified with experiments.A stochastic model for contact surfaces at polymer interfaces subjected to an electrical fieldsubmittedVersio

Long lines in urban development : an analysis of development programs 1982-2000 and their impact on modern planning

I dagens planlegging er det slik at kollektivtrafikk som skal være styrende for utbygging, i tillegg til at fortetting rundt knutepunkt er sentralt. Slik har det ikke alltid vært, og veien dit har vært lang. Ved å se på en rekke utviklingsprogrammer i regi av Miljøverndepartementet mellom 1980-tallet til 2000- tallet, kan man se hvordan og hvorfor dagens planleggingstankegang oppsto. Fra bilens inntog i Norge på begynnelsen av 1900-tallet, økte bilbruken i norske byer betraktelig. Etter bilslippet i 1960, skjøt veksten ytterligere fart. Da Brundtlandkommisjonen ble lagt frem kom diskursen om bærekraft opp i lyset, og endret mye av måten man tenkte på. Fra et utspring i alle problemene bilen skapte og fra Brundtlandkommisjonenn ble det satt i gang to linjer med utviklingsprogrammer, hvor neste program bygget på det forrige. Disse to linjene møttes til slutt i Miljøbyprogrammet (1993-2000) hvor en modell for den miljøvennlige byen ble laget. I denne oppgaven sees det videre på arven fra modellen som kan finnes i nylige planer, flere tiår etter. Dermed kan man se at dagens planer bygger på premisser godt over 40 år gamle. I oppgaven analyserer dataen gjennom synet til historisk institusjonalisme og en variant av ASID modellen. Her analyseres forholdet mellom handlingsrom, bystruktur, institusjoner og diskurs.M-BYRE