The Hydraulic Jump in Liquid Helium

We present the results of some experiments on the circular hydraulic jump in normal and superfluid liquid helium. The radius of the jump and the depth of the liquid outside the jump are measured through optical means. Although the scale of the apparatus is rather small, the location of the jump is found to be consistent with the assumption that the jump can be treated as a shock, if the surface tension is taken into account. The radius of the jump does not change when going down in temperature through the lambda point; we think that the flow is supercritical. A remarkable feature of the experiment is the observation of stationary ripples within the jump when the liquid is superfluid.Comment: Submitted to the proceedings of the 24th International Conference on Low Temperature Physics. 2 figure

Can a Kasner Universe with a Viscous Cosmological Fluid be Anisotropic?

A Bianchi type -I metric of Kasner form is considered, when the space is filled with a viscous fluid. Whereas an ideal (nonviscous) fluid permits the Kasner metric to be anisotropic provided that the fluid satisfies the Zel'dovich equation of state, the viscous fluid does not permit the Kasner metric to be anisotropic at all. In the latter case, we calculate the Kasner (isotropic) metric expressed by the fluid's density, pressure, and bulk viscosity, at some chosen instant $t=t_0$. The equation of state is also calculated. The present paper is related to a recent Comment of Cataldo and del Campo [Phys. Rev. D, scheduled to April 15, 2000], on a previous work of the present authors [Phys. Rev. D {\bf 56}, 3322 (1997)].Comment: 8 pages, LaTeX, no figures. To appear in PR

Balansert målstyring i kommuner: En casestudie av 12 kommuner.

Formålet for denne studien er å bidra til økt kunnskap om hvordan balansert målstyring (BMS) brukes i norske kommuner og om hvilke forhold som kan forklare ulike virkninger. Denne casestudien bygger på data fra 12 kommuner. Kritikk de senere år om feil fokus og dysfunksjonelle virkninger, spesielt knyttet til statlige etaters mål- og resultatstyring, utfordrer også kommunenes praksis. Likevel blir samfunnet stadig mer resultatorientert og kommunene møter økende krav og forventninger fra statlige myndigheter og egne innbyggere. BMS forblir derfor et aktuelt styringsverktøy. Studien bygger på en innhenting av kommunenes oppfatninger gjennom bruk av elektronisk spørreskjema, analyse av styringsdokumenter, sekundærdata fra offentlige kilder og direkte kontakt med casekommunene. I studien har vi sett på hvordan størrelse, politiske forhold, økonomisk utvikling, administrativ stabilitet og organisering knyttet til den enkelte kommune påvirker virkingene kommunen har av BMS. Våre funn indikerer at små og mellomstore kommuner får mer ut av BMS enn de store kommunene. Hvem som utgjør største politiske konstellasjon i en kommune er også av betydning for virkningen av BMS. Kommuner med dårligst økonomisk utvikling oppgir klart størst virkning. Videre så ser vi at kommuner som har tonivåmodell vurderer at de oppnår mer med BMS enn kommuner med flere ledernivåer. Det er vanskelig å se samme sammenheng mellom antall rådmannsskifter og virkning av BMS. Kommunene har til en viss grad fått til aktiv bruk av resultatinformasjon i enhetene, men i liten grad erfaringsutveksling mellom enheter. BMS brukes i liten grad til å stille krav om omstilling. Strategi- og målekart er sentralt i teorien som ligger bak balansert målstyring. Bruk av strategi-kart er svært lite utbredt i casekommunene, og 4 av 12 kommuner bruker heller ikke målekart. Flere av casekommunene innførte BMS på begynnelsen av 2000-tallet. Etter ca. 10 års drift står mange kommuner nå ved et veiskille, hvor de bør vurdere hva de har fått til så langt og hva som er veien videre. Det er få fellesnevnere mellom hva kommunene legger i BMS og hvordan dette praktiseres. Flertallet av kommunene har et opplegg som er et godt stykke unna «idealmodellen» i teorien om balansert målstyring til Kaplan og Norton. Vårt inntrykk, ut i fra hvordan BMS praktiseres i flere av casekommunene, er at kommunene i for stor grad gjør en «rituell tilpasning» til bruk av et verktøy som BMS.The purpose of this study is to contribute to increased knowledge about how balanced scorecard (BSC) is used in Norwegian municipalities and about the factors that may explain the different effects. This case study is based on data from 12 municipalities. Criticism during the last years concerning wrong focus and dysfunctional effects, particularly related to the government agencies' goals and results, also challenges the practice in local municipalities. Nevertheless, society is becoming more results-oriented and municipalities face increasing demands and expectations from government authorities and citizens. BSC therefore remains an appropriate management tool. Our study is based on data collection through the use of electronic questionnaires, analysis of policy documents, secondary data from public sources and direct contact with the municipalities. In the study we looked at the following factors; size, political conditions, economic development, administrative stability and organization. Our findings indicate that small and medium-sized municipalities benefit more from BSC than the large municipalities. The political constellation in a municipality is also of importance for the effect of BSC. Municipalities with the poorest economic development specified clearly the greatest effect. Furthermore, we see that municipalities that have a two-level organizational model report that they achieve more with BSC than municipalities with multiple levels of management. It is difficult to see any clear correlation between changes of chief municipal executive and outcome of BSC. We see that the municipalities to some extent have achieved the active use of performance information in each unit. But little is done in order to exchange knowledge between the units and to design requirements for further development. Strategy and measurement maps are central to the theory underlying the balanced scorecard. The use of strategy maps is not widespread in the case municipalities, and 4 of the 12 municipalities do not use measuring maps. Several of the case municipalities introduced BSC early in the 2000s. After approximately 10 years of operation, many municipalities are now at a crossroad, where they should evaluate the achievements so far and consider the way forward. We have found few common denominators between what municipalities put into BSC and how it is practiced. Our main impression is that the majority of municipalities have a practice that is not in accordance with the model of Kaplan and Norton. Our impression, based on how BSC is practiced in several of the case municipalities, is that the use to a large extent is a "ritual adaptation".Master i styring og ledels

Achieving Sustainability Through Geodata: An Empirical Study of Challenges and Barriers

Master's thesis in Information systems (IS501)Research within data management is often based on the elements of the data lifecycle. Organizations and businesses are also becoming more interested in data lifecycle management to leverage their data streams, compounded by an interest in geographical attributes within the data –referred to as geodata. Geodata provides a richer basis for analysis and is increasingly important within urban planning. Furthermore, the pressure to achieve sustainability goals calls for improving the data lifecycle. The challenge remainsas to what can be improvedwithin the data lifecycle –with geodata as an important input –to achieve sustainability dimensions. Our main contribution through this study is shedding light on challenges withgeodata from an Information Systems (IS) and sustainability perspective. Additionally, the identified challenges are also feedback to data management research and the data lifecycle

Melting in multilayer adsorbed films

We present both an improved model and new experimental data concerning the problem of melting in multilayer adsorbed films. The model treats in a mutually consistent manner all interfaces in a stratified film. This results in the prediction of substrate freezing, a phenomenon thermodynamically analogous to surface melting. We also compare the free energies of stratified films to those of homogeneous films. This leads to an orderly classification of multilayer phase diagrams in the vicinity of the bulk triple point. The results of the model are compared with the experimentally known systems. Of these, only methane/graphite exhibits melting from homogeneous solid to homogeneous liquid in multilayer films. The systems Ne/graphite and Ar/graphite, studied by Zhu and Dash, exhibit surface melting and substrate freezing instead. We observe experimentally, by means of pulsed nuclear magnetic resonance, that melting in methane adsorbed on graphite extends below the film thickness at which the latent heat of melting is known to vanish. The multilayer melting curve in this system is a first-order prewetting transition, extending from triple-point dewetting at bulk coexistence down to a critical point where the latent heat vanishes at about four layers, and apparently extending to thinner films as a higher-order, two-dimensional phase transition. It would therefore seem that methane/graphite is an ideal system in which to study the evolution of melting from two dimensions to three dimensions

Bound states of 3He at the edge of a 4He drop on a cesium surface

We show that small amounts of 3He atoms, added to a 4He drop deposited on a flat cesium surface at zero temperature, populate bound states localized at the contact line. These edge states show up for drops large enough to develop well defined surface and bulk regions together with a contact line, and they are structurally different from the well-known Andreev states that appear at the free surface and at the liquid-solid interface of films. We illustrate the one-body density of 3He in a drop with 1000 4He atoms, and show that for sufficiently large number of impurities, the density profiles spread beyond the edge, coating both the curved drop surface and its flat base and eventually isolating it from the substrate.Comment: 10 pages and 7 figures. Submitted to PR

The Patterns of High-Level Magnetic Activity Occurring on the Surface of V1285 Aql: The OPEA Model of Flares and DFT Models of Stellar Spots

Statistically analyzing Johnson UBVR observations of V1285 Aql during the three observing seasons, both activity level and behavior of the star are discussed in respect to obtained results. We also discuss the out-of-flare variation due to rotational modulation. Eighty-three flares were detected in the U-band observations of season 2006 . First, depending on statistical analyses using the independent samples t-test, the flares were divided into two classes as the fast and the slow flares. According to the results of the test, there is a difference of about 73 s between the flare-equivalent durations of slow and fast flares. The difference should be the difference mentioned in the theoretical models. Second, using the one-phase exponential association function, the distribution of the flare-equivalent durations versus the flare total durations was modeled. Analyzing the model, some parameters such as plateau, half-life values, mean average of the flare-equivalent durations, maximum flare rise, and total duration times are derived. The plateau value, which is an indicator of the saturation level of white-light flares, was derived as 2.421{\pm}0.058 s in this model, while half-life is computed as 201 s. Analyses showed that observed maximum value of flare total duration is 4641 s, while observed maximum flare rise time is 1817 s. According to these results, although computed energies of the flares occurring on the surface of V1285 Aql are generally lower than those of other stars, the length of its flaring loop can be higher than those of more active stars.Comment: 44 pages, 10 figures, 5 tables, 2011PASP..123..659

The statistical analyses of flares detected in B band photometry of UV Ceti type stars

In this study, we present the unpublished flare data collected from 222 flares detected in the B band observations of five stars and the results derived by statistical analysis and modeling of these data. Six basic properties have been found with a statistical analysis method applied to all models and analyses for the flares detected in the B band observation of UV Ceti type stars. We have also compared the U and B bands with the analysis results. This comparison allowed us to evaluate the methods used in the analyses. The analyses provided the following results. (1) The flares were separated into two types, fast and slow flares. (2) The mean values of the equivalent durations of the slow and the fast flares differ by a factor of 16.2 \pm 3.7. (3) Regardless of the total flare duration, the maximum flare energy can reach a different Plateau level for each star. (4) The Plateau values of EV Lac and EQ Peg are higher than the others. (5) The minimum values of the total flare duration increase toward the later spectral types. This value is called the Half-Life value in models. (6) Both the maximum flare rise times and the total flare duration obtained from the observed flares decrease toward the later spectral types.Comment: 17 pages, 10 figures, 8 table

Proton tracking in a high-granularity Digital Tracking Calorimeter for proton CT purposes

Radiation therapy with protons as of today utilizes information from x-ray CT in order to estimate the proton stopping power of the traversed tissue in a patient. The conversion from x-ray attenuation to proton stopping power in tissue introduces range uncertainties of the order of 2-3% of the range, uncertainties that are contributing to an increase of the necessary planning margins added to the target volume in a patient. Imaging methods and modalities, such as Dual Energy CT and proton CT, have come into consideration in the pursuit of obtaining an as good as possible estimate of the proton stopping power. In this study, a Digital Tracking Calorimeter is benchmarked for proof-of-concept for proton CT purposes. The Digital Tracking Calorimeteris applied for reconstruction of the tracks and energies of individual high energy protons. The presented prototype forms the basis for a proton CT system using a single technology for tracking and calorimetry. This advantage simplifies the setup and reduces the cost of a proton CT system assembly, and it is a unique feature of the Digital Tracking Calorimeter. Data from the AGORFIRM beamline at KVI-CART in Groningen in the Netherlands and Monte Carlo simulation results are used to in order to develop a tracking algorithm for the estimation of the residual ranges of a high number of concurrent proton tracks. The range of the individual protons can at present be estimated with a resolution of 4%. The readout system for this prototype is able to handle an effective proton frequency of 1 MHz by using 500 concurrent proton tracks in each readout frame, which is at the high end range of present similar prototypes. A future further optimized prototype will enable a high-speed and more accurate determination of the ranges of individual protons in a therapeutic beam.Comment: 21 pages, 8 figure