The 22 GHz radio-aeronomy receiver at Onsala Space Observatory

We present a radiometer system for regular long-term measurements of water vapour in the middle atmosphere. To be able to do continuous and long-term measurements a simple, robust, reliable and automatic system is needed. Our system therefore is based on a stable, uncooled, HEMT amplifier frontend and on a digital spectrometer backend. In order to minimise reflections in the frontend transmission line, which distort the signal due to standing waves, we have designed a corrugated receiver horn, which combines good characteristics (low return loss and sidelobes) and narrow beamwidth to simplify the receiver optics. In order to make the radiometer system as simple as possible, we use the sky as the calibration cold load. This is possible since we use the observed brightness temperatures of an already existing broadband dual-channel 21.0/31.4-GHz radiometer, at the observation site, to estimate the brightness temperature of the sky at . However, we have developed a calibration method, which makes it possible to estimate the sky brightness temperature even if we cannot use the dual-channel radiometer. Despite new measurements, which became available in recent years, the determination of middle atmospheric water vapour distribution still remains a challenge due to the fact that there is a large dispersion among the different measurement methods and data sets, which are obtained on a sparse and sporadic basis. This is the reason why several instruments similar to ours currently are developed in Europe

Hydroxyl, water, ammonia, carbon monoxide and neutral carbon towards the Sgr A complex

We observed OH, H$_2$O, HN$_3$, C$^{18}$O, and C$_I$ towards the +50 km/s cloud (M-0.02-0.07), the CND and the +20 km/s (M-0.13-0.08) cloud in the Sgr A complex with the VLA, Odin and SEST. Strong OH absorption, H$_2$O emission and absorption lines were seen at all three positions. Strong C$^{18}$O emissions were seen towards the +50 and +20 km/s clouds. The CND is rich in H$_2$O and OH, and these abundances are considerably higher than in the surrounding clouds, indicating that shocks, star formation and clump collisions prevail in those objects. A comparison with the literature reveals that it is likely that PDR chemistry including grain surface reactions, and perhaps also the influences of shocks has led to the observed abundances of the observed molecular species studied here. In the redward high-velocity line wings of both the +50 and +20 km/s clouds and the CND, the very high H$_2$O abundances are suggested to be caused by the combined action of shock desorption from icy grain mantles and high-temperature, gas-phase shock chemistry. Only three of the molecules are briefly discussed here. For OH and H$_2$O three of the nine observed positions are shown, while a map of the C$^{18}$O emission is provided. An extensive paper was recently published with Open Access (Karlsson et al. 2013; http://www.aanda.org/articles/aa/pdf/2013/06/aa20471-12.pdf ).Comment: Proc. of a Conf. on IAU Symposium No.303: The Galactic Center: Feeding and Feedback in a Normal Galactic Nucleus 2013, Santa Fe, NM (USA

CO in OH/IR stars close to the Galactic centre

Aims: A pilot project has been carried out to measure circumstellar CO emission from three OH/IR stars close to the Galactic centre. The intention was to find out whether it would be possible to conduct a large-scale survey for mass-loss rates using, for example, the Atacama Large Millimeter Array (ALMA). Such a survey would increase our understanding of the evolution of the Galactic bulge. Methods: Two millimetre-wave instruments were used: the Nobeyama Millimeter Array at 115 GHz and the Submillimeter Array at 230 GHz. An interferometer is necessary as a `spatial filter' in this region of space because of the confusion with interstellar CO emission. Results: Towards two of the stars, CO emission was detected with positions and radial velocities coinciding within the statistical errors with the corresponding data of the associated OH sources. However, for one of the stars the line profile is not what one expects for an unresolved expanding circumstellar envelope. We believe that this CO envelope is partially resolved and that this star therefore is a foreground star not belonging to the bulge. Conclusions: The results of the observations have shown that it is possible to detect line profiles of circumstellar CO from late-type stars both within and in the direction of the Galactic bulge. ALMA will be able to detect CO emission in short integrations with sensitivity sufficient to estimate mass-loss rates from a large number of such stars.Comment: 5 pages, 3 figure

Modeling Determinants of First-Day Returns from IPOs

The primary purpose of this paper is to find the determinants of first-day returns on the Stockholm Stock Exchange. Our research will cover the 1996 – 2004 periods. Our secondary purpose is intended to find a profitable trading strategy with regard to future IPOs on the Stockholm Stock Exchange. By using regression analysis, focusing on company specific factors and the IPO process, we hope to find a function exhibiting statistical significance, determining future first-day returns from which construction of a profitable trading strategy will be possible. We have chosen a deductive attempt with a quantitative procedure through which we can draw general results. More specifically, we use multiple regression models to attain our purpose. IPO literature has generally done a good job in covering the theoretical perspective on why first-day returns exist. Within this area, Ritter is the foremost authority. The method of predicting first-day returns is derived from the assumption that first-day returns are explained as a function of company characteristics, stock market cycle and how the IPO is conducted. Our empirical foundation is built upon 258 firms, of which 124 where identified as clean IPOs. From this sample we were able to collect data, supplied by FI, in the form of company listing prospectuses, on 107 firms. Although our findings can be deemed successful, we have failed to find a model that determines first-day returns. This revelation is hardly surprising since doing so is virtually impossible. Instead, our findings show, with a high degree of certainty, which behavioural characteristics can be expected during the first-day of trading, given the input variables we have chosen. These results are what we base our trading strategy on

Alternativ för anestesi av kanin

Risken att dö i samband med sedering eller anestesi är cirka åtta gånger högre för kaniner än för hundar. De flesta dödsfall sker 0-3 timmar efter sedering eller anestesi. Syftet med detta arbete är att undersöka de olika alternativen vid anestesi av kanin med fokus på att jämföra inhalations- och injektionsläkemedel, samt att försöka hitta en förklaring till den höga mortaliteten. Anestesi kan genomföras på ett flertal sätt. Induktion och upprätthållande av anestesi kan ske via inhalation eller injektion. Administrationssätten och de olika läkemedlen går även att kombinera på flera sätt, till exempel genom att inducera via injektion och upprätthålla anestesi via inhalation. Vid induktion med inhalationsläkemedel upplever kaniner obehag och håller andan under långa perioder. Propofol, kombination av opioid och sederande läkemedel eller ketamin-midazolam-xylazin kan användas för total intravenös anestesi (TIVA). Apné och andningsdepression är vanliga bieffekter vid användning av anestesiläkemedel på kanin. Ofta är syresättningen dålig och för att förebygga detta bör kaniner få andas in syrgas under induktion och hela narkostiden. Särskilt vid användning av TIVA och opioidkombinationer bör beredskap finnas för att mekaniskt ventilera djuret. Ketamin och bensodiazepiner orsakar inte allvarliga negativa effekter på andningen vid kliniska doser. Slutsatsen är att mycket kan göras för att förbättra anestesi för kaniner. Generellt bör kaniner intuberas och få andas syrgas under anestesin, oavsett vilket/vilka läkemedel som används samt att induktion med narkosgaser bör undvikas. Ketamin och bensodiazepiner är en lovande kombination av läkemedel. TIVA är ett fördelaktigt alternativ ur miljösynpunkt eftersom substanser för inhalation är växthusgaser. Användning av dessa bör därför hållas till ett minimum. Orsaken bakom den höga dödligheten för kaniner i samband med sedering och anestesi är svårt att förklara med aktuell kunskap. Idag finns inga tydliga svar men många faktorer kan spela in. Det är ett outforskat område där mycket kan förbättras i framtiden med forskningens hjälp.Rabbits have a mortality risk in connection with sedation and anaesthesia about eight times higher compared to dogs. Most deaths occur postoperatively, within three hours after sedation or anaesthesia. The aim with this paper is to investigate the different alternatives for anaesthesia in rabbits and to compare inhalation and injection agents. An answer to the question of why rabbits have such a high risk of death will also be examined. The two main options regarding anaesthetic protocol are the choice of induction and maintenance by inhalation or injection agents. The different ways of administration can be combined, for example induction by injection and maintenance with inhalation agents. Induction with solely inhalation agents is very unpleasant for rabbits and it is common for rabbits to hold their breath during long periods of time. Total intravenous anaesthesia (TIVA) can be accomplished with a number of substances, for example propofol, opioid-sedative or ketamine-midazolame-xylazine. Apnea and respiratory depression are commonly occurring side effects during anaesthesia in rabbits and oxygenation is often poor regardless of which drug combinations are used. During TIVA-protocol and with the use of opioid combinations, practitioners should be prepared to mechanically ventilate the patient. Ketamine and benzodiazepines only have minor effects on respiration when given in clinical doses. In conclusion, a lot can be done to improve anaesthesia in rabbits. Rabbits should be intubated and allowed to inhale oxygen during anaesthesia. Induction solely by inhalation is not recommended. Ketamine and benzodiazepines is a promising combination of drugs. TIVA is favorably from an environmental standpoint because substances used for inhalation are greenhouse gasses. Their use should therefore be held to a minimum. The reasons behind the higher risk of death is difficult to answer with current knowledge. There is much research to be done in different areas before an answer could be possible. With the help of this research much can be done to improve the survival of rabbits following anesthesia

Longest continous ground-based measurements of mesospheric CO

The longest continuous series of ground-based measurements of mesospheric CO is presented. The continuous data cover the period September 2000 to September 2002. Sporadic measurements from 1988 and 1989 are also reported. The results show a large CO accumulation in the winter mesosphere, which is consistent with generally accepted ideas about the seasonally-varying mean meridional circulation. Comparison of the observations with simulations by the Whole Atmosphere Community Climate Model (WACCM) indicate that the model can reproduce the observed seasonal cycle as well as much of its variability, although calculated columns amounts are smaller than the largest values seen in the data

Samhandling og læring i et introduksjonsemne i fysikk basert på digital Peer Instruction

I de senere år har det vært en skifte mot økt bruk av digitale former for undervisning, og i 2020 ble dette spesielt framskyndet fordi brorparten av undervisningen på universitetsnivå måtte foregå digitalt på grunn av koronapendemien. Det er også voksende interesse for mer studentaktive undervisningsformer for å oppnå bedre læringsutbytte. Dette åpner for nye spørsmål rundt digitale studentaktive undervisningsmetoder. Denne studien undersøker: 1) læringsutbyttet i et introduksjonsemne i fysikk gjennomført ved digital Peer Instruction med faste grupper; 2) kjennetegnene til produktive diskusjoner i denne settingen. Forskningsspørsmålene er undersøkt kvantitativt ved før- og ettertester, og kvalitativt ved å analysere opptak av digitale læringssituasjoner. Studentenes konseptuelle forståelse har blitt kartlagt ved Force Concept Inventory (FCI) ved begynnelsen og slutten av semesteret. Det normaliserte gainet på 0,46 og verdi for Cohens d på 0,88 er sammenlignbare med typiske verdier fra aktive undervisningsformer i en fysisk setting. I Peer Instruction svarer studentene på oppgaver før og etter en gruppediskusjon. Antallet studenter på hver gruppe som svarer riktig før og etter diskusjonen viser at i grupper på tre bør minst én ha svart riktig før diskusjonen for at gruppen skal komme til rett svar. I større grupper bør det være minst to som har svart riktig før diskusjonen. Det er klar sammenheng mellom enkeltstudentenes prestasjon på FCI førtesten og oppgavene før diskusjon. Analysen av opptakene viser at studentene med høy poengsum på FCI førtesten ofte dominerer diskusjonene, mens de andre ikke bidrar mye. Resultatene viser at digital Peer Instruction med faste grupper gir sammenlignbart læringsutbytte med andre former for aktiv undervisning, men analysen av gruppediskusjonene og diskusjonsoppgavene viser at undervisere bør passe på gruppesammensetning og oppmuntre alle studentene til å delta i diskusjonene

Variability of water masers in evolved stars on timescales of decades

For several decades (1987-2015) we have been carrying out observations of water masers in the circumstellar envelopes (CSE's) of Mira variables, Red Supergiants (RSG's) and Semi-Regular Variables (SRV's) with the Medicina 32-m and Effelsberg 100-m antennas. The single-dish monitoring observations provide evidence for strong H2O maser profile variations, which likely are connected to structural changes in the maser shells. Such variations include strong flares in intensity lasting several (tens of) months and systemic velocity gradients of maser components developing over years, as well as other secular variations which are superimposed on periodic variations following the stellar light variations. When complemented with interferometric observations, it is possible to derive the 3-D distribution of the maser spots, and their lifetime, as we have done for RX Boo (Winnberg et al. 2008) and U Her (Winnberg et al. 2011; Brand et al. in prep.)

Lifetime of OH masers at the tip of the asymptotic giant branch

Context: A large fraction of otherwise similar asymptotic giant branch stars (AGB) do not show OH maser emission. As shown recently, a restricted lifetime may give a natural explanation as to why only part of any sample emits maser emission at a given epoch. Aims: We wish to probe the lifetime of 1612 MHz OH masers in circumstellar shells of AGB stars. Methods: We reobserved a sample of OH/IR stars discovered more than 28 years ago to determine the number of stars that may have since lost their masers. Results: We redetected all 114 OH masers. The minimum lifetime inferred is 2800 years (1 sigma). This maser lifetime applies to AGB stars with strong mass loss leading to very red infrared colors. The velocities and mean flux density levels have not changed since their discovery. As the minimum lifetime is of the same order as the wind crossing time, strong variations in the mass-loss process affecting the excitation conditions on timescales of ~3000 years or less are unlikely. Keywords: OH masers -- Stars: AGB and post-AGB -- circumstellar matterComment: 8 pages, 5 figures, accepted for publication in Astronomy & Astrophysic

A new sample of OH/IR stars in the Galactic center

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