The spectroscopic parameters of sodium cyanide, NaCN (X 1A'), revisited

The study of the rotational spectrum of NaCN (X $^1$A') has recently been extended in frequency and in quantum numbers. Difficulties have been encountered in fitting the transition frequencies within experimental uncertainties. Various trial fits traced the difficulties to the incomplete diagonalization of the Hamiltonian. Employing fewer spectroscopic parameters than before, the transition frequencies could be reproduced within experimental uncertainties on average. Predictions of $a$-type $R$-branch transitions with $K_a \le 7$ up to 570 GHz should be reliable to better than 1 MHz. In addition, modified spectroscopic parameters have been derived for the 13C isotopic species of NaCN.Comment: 5 pages, no figure, J. Mol. Spectrosc., appeared; CDMS links update

AEOLIAN DUNE FIELDS OF KANSAS AND THEIR RESPONSE TO LATE-QUATERNARY DROUGHT

Aeolian dune fields are ubiquitous features of the North American Great Plains, and contained within their stratigraphy are important records of changes in prehistoric climate. Using absolute dating techniques, researchers can determine the timing of past dune field activity, which in many cases, is the result of drought. Based on a drought-aeolian activity relationship, the timing of past dune activity can, therefore, be used as a proxy for prehistoric drought. This dissertation presents three chronologies of dune activity from understudied dune fields in Kansas. Each chronology has been established using new optically stimulated luminescence ages, which in total account for nearly 25% of the total luminescence ages reported from all U.S. Great Plains dune fields. In general, dune activity in Kansas is coeval with that recorded throughout the Great Plains, but, in particular, Kansas dunes were active during defined periods of drought recorded in other regional proxies

Differentielle Beteiligung von RhoA, -B und -C an zellulären Prozessen und Wirt-Pathogen-Interaktionen

Mammalian Rho GTPases play a key role in regulating the actin cytoskeleton during processes such as cellular trafficking or cell division. RhoA, Rac1 and Cdc42 have been studied extensively in the past. The closely related RhoB and RhoC proteins share 85% sequence identity with RhoA. Nevertheless, RhoB and RhoC have mostly been neglected in the past, since many studies failed to distinguish between Rho subfamily members. Moreover, various pathogens activate or inactivate Rho family GTPases during infection processes to manipulate the actin cytoskeleton. RhoA was studied in this context, but little is known of RhoB and RhoC. For a distinct analysis of RhoA, RhoB and RhoC functions in cellular and infection processes, genetic knockouts of all three proteins were generated, as single deletions and in double combinations, in the murine fibroblast cell line NIH-3T3. Elimination of RhoA, alone or in combination with RhoB or RhoC, slowed down cellular growth and increased the number of multinucleated cells. Deletion of one or two proteins led to an upregulation of the remaining Rho proteins, which was most prominent for RhoB in the absence of RhoA and/or RhoC. Changes of F-actin content were subtle in most cases, while stress fiber formation in RhoAB double KO cells was strongly reduced. In the presence of RhoA and RhoC and the absence of RhoB, namely in RhoB KO cells, Rho kinase expression as well as myosin light chain phosphorylation were increased the most, which is in line with increased F-actin intensities in the same cell type. Moreover, the actin depolymerizing factor Cofilin was found to be upregulated in the absence of Rho. Knockdown of all three Cofilin proteins led to massive induction of stress fibers. Salmonella Typhimurium required RhoA together with RhoC for efficient invasion at early time points. Interestingly, RhoB was strongly upregulated during later stages of infection, which was dependent on the S. Typhimurium effector SopB. The invasion capacity of Shigella flexneri was found to decrease to 20% in the absence of RhoA. In conclusion, the data from this study reveal antagonistic roles for RhoA and RhoB. Furthermore, RhoC appears to promote RhoA activity. Taken together, the Rho single and double KO cell lines generated during this study allow for the first time precise dissection of respective Rho subfamily functions and their differential contributions to fundamental cell biological processes as well as to bacterial or viral infections.Rho GTPasen spielen in Säugerzellen eine Schlüsselrolle in der Regulation des Aktin Zytoskeletts. RhoA, Rac1 und Cdc42 wurden in der Vergangenheit intensiv analysiert. Die Proteine RhoB und RhoC weisen eine 85%ige Sequenzidentität zu RhoA auf. In vielen Studien wurde jedoch nicht zwischen den drei Proteinen unterschieden. Außerdem aktivieren oder inaktivieren viele Pathogene Rho GTPasen während der Infektion um das Aktin Zytoskelett zu manipulieren. Eine Rolle für RhoA wurde in diesem Kontext bereits nachgewiesen, aber auch hier wurden RhoB und RhoC meist vernachlässigt. Für eine differenzierte Analyse von RhoA, RhoB und RhoC wurden genetische Knockouts von allen drei Proteinen, einzeln und in Doppel-Kombinationen, in der murinen Fibroblasten-Zelllinie NIH-3T3 induziert. Deletion von RhoA, alleine oder zusätzlich zu RhoB oder RhoC, verlangsamte zelluläres Wachstum und erhöhte die Anzahl an Zellkernen pro Zelle. Die Deletion eines Rho Proteins führte zur erhöhten Expression der verbleibenden Rho Proteine, was besonders für RhoB in der Abwesenheit von RhoA und/oder RhoC der Fall war. Die Menge an F-Aktin war in den meisten Fällen kaum verändert, außer bei RhoAB Doppel KOs, in denen Stressfaserbildung deutlich reduziert war. In RhoB KO Zellen, in denen die Expression von RhoA erhöht und RhoC auch exprimiert war, wurden erhöhte Mengen von Rho Kinase Expression und Myosin Phosphorylierung nachgewiesen, was mit erhöhter F-Aktin Menge einherging. Weitere Analysen zeigten eine erhöhte Expression von Proteinen der Cofilin Familie in der Abwesenheit von Rho, welche für die Depolymerisation von Aktin zuständig sind. Infektionsversuche zeigten eine Rolle für RhoA und RhoC während der frühen Invasion von Salmonella Typhimurium. RhoB wurde dagegen in späten Phasen der Infektion hochreguliert, was vom bakteriellen Protein SopB abhängig war. Bei Shigella flexneri sank die Invasionsrate in der Abwesenheit von RhoA noch weiter als für S. Typhimurium, auf 20%. Zusammenfassend zeigen die Daten dieser Arbeit, dass RhoA und RhoB antagonistische Funktionen aufweisen. Außerdem scheint RhoC die Aktivität von RhoA zu begünstigen. In der Gesamtheit lässt sich sagen, dass die Rho KO Zellen, die in dieser Studie generiert wurden, erstmalig eine spezifische Analyse der Funktionen der einzelnen Rho Proteine ermöglichen. Auf diesem Wege können ihre charakteristischen Funktionen für zelluläre Prozesse und bakterielle und virale Infektionen detailliert analysiert werden

Detection of the simplest sugar, glycolaldehyde, in a solar-type protostar with ALMA

Glycolaldehyde (HCOCH2OH) is the simplest sugar and an important intermediate in the path toward forming more complex biologically relevant molecules. In this paper we present the first detection of 13 transitions of glycolaldehyde around a solar-type young star, through Atacama Large Millimeter Array (ALMA) observations of the Class 0 protostellar binary IRAS 16293-2422 at 220 GHz (6 transitions) and 690 GHz (7 transitions). The glycolaldehyde lines have their origin in warm (200-300 K) gas close to the individual components of the binary. Glycolaldehyde co-exists with its isomer, methyl formate (HCOOCH3), which is a factor 10-15 more abundant toward the two sources. The data also show a tentative detection of ethylene glycol, the reduced alcohol of glycolaldehyde. In the 690 GHz data, the seven transitions predicted to have the highest optical depths based on modeling of the 220 GHz lines all show red-shifted absorption profiles toward one of the components in the binary (IRAS16293B) indicative of infall and emission at the systemic velocity offset from this by about 0.2" (25 AU). We discuss the constraints on the chemical formation of glycolaldehyde and other organic species - in particular, in the context of laboratory experiments of photochemistry of methanol-containing ices. The relative abundances appear to be consistent with UV photochemistry of a CH3OH-CO mixed ice that has undergone mild heating. The order of magnitude increase in line density in these early ALMA data illustrate its huge potential to reveal the full chemical complexity associated with the formation of solar system analogs.Comment: Accepted for publication in ApJ Letter

A survey of hnco and ch3nco in molecular clouds

Following the first interstellar detection of CH$_3$NCO in Sgr B2(N) by Halfen et al. (2015), a survey of this species and its likely precursor HNCO has been conducted towards several dense molecular clouds. Three transitions of CH$_3$NCO in its $K_a$ = 0 ladder for both A and E internal rotation states were searched for at 3 mm, using the new ARO ALMA Prototype 12 m telescope. In addition, two transitions of HNCO in its $K_a$ = 0 and 2 ladders were observed near 88 and 110 GHz. Emission from CH$_3$NCO was detected towards Orion-KL, G34.3, W51M, Sgr B2(2N), and DR-21(OH) with intensities of T$_A$^ $\approx$ 10-40 mK. HNCO was also found in each source observed. The ratio of HNCO/CH$_3$NCO estimated from these data is around 25 - 45, consistent with that derived from Sgr B2(N). These results suggest that HNCO is most likely the chemical precursor to CH$_3$NCO

Complete results from a spectral-line survey of Sgr B2(N)

A confusion-limited spectral line survey of the Galactic center molecular cloud Sgr B2(N) at 3, 2, and 1 mm (68 - 116, 130 - 172, and 210 - 280 GHz) using the Kitt Peak 12 m and the Submillimeter Telescope (SMT) of the Arizona Radio Observatory was recently completed. About 15,000 spectral lines were observed in the survey range. The data have been analyzed using two techniques. First, the rotational temperature diagram methods was used for each individual species. Second, an LTE code was used to model and ultimately fit the data to a set of parameters for each species, using a least squares approach. Seventy-four molecules are identified in the data, along with 81 isotopologue species. In addition, 26 excited vibrational states of the identified molecules were detected, as well as H and He recombination lines. Source and Galactic absorption lines are seen in several abundant species, as well as multiple maser lines of methanol and possibly SO$_2$

Klimaregimets manglende effektivitet: Et bevisst valg eller manglende kunnskap? : En teoretisk fortolkende case-studie med utgangspunkt i to tilnærminger til vår tids største utfordring

Klimaendringer har blitt beskrevet som vår tids største utfordring. Etter nærmere 20 år med klimaforhandlinger og forsøk på å etablere et effektivt klimaregime er det fortsatt langt igjen til en løsning. De globale utslippene av klimagasser har økt formidabelt siden FNs Klimakonvensjon ble fremforhandlet i 1992. Konvensjonen hadde som målsetning at utviklede land skulle “return by the end of the present decade to earlier levels of anthropogenic emissions of carbon dioxide and other gases” og oppfordret partene til, individuelt eller kollektivt, å implementere tiltak som kunne stabilisere utslippene på 1990-nivå. Kyoto-protokollen, som skulle følge opp denne målsetningen, ser heller ikke ut til å frembringe vesentlige utslippsreduksjoner. Og vesentlige utslippsreduksjoner er i følge FNs klimapanel (IPCC) nødvendige dersom verden skal unngå en global oppvarming som kan medføre farlige klimaendringer. Formålet med denne oppgaven er å forklare hvorfor man så langt ikke har klart å etablere et effektivt klimaregime og hva som vil være den beste veien videre for å kunne realisere dette i nærmeste fremtid. Dette er en formidabel målsetning og jeg har avgrenset den ved å ta utgangspunkt i tilnærmingene til to sentrale teoretikere, henholdsvis Scott Barrett og Peter M. Haas, som tilhører to ulike skoleretninger innenfor studiet av internasjonalt samarbeid. Grunnen til at jeg har valgt å vektlegge akkurat Barretts og Haas´ tilnærminger er at de har det til felles at de begge mener at det hadde vært mulig å etablere et mer effektivt klimaregime enn det vi forholder oss til i dag og at begge har klare ideer om hvordan en fremtidig utvikling kan realisere dette. Denne oppgaven tar form av å være en teoretisk fortolkende case-studie hvor jeg benytter to teoretiske tilnærminger som gir forskjellige forklaringer på den manglende effektiviteten under det eksisterende klimaregimet. Jeg har et spesielt fokus på Kyoto-protokollen som fremstår som klimaregimets mest sentrale komponent. Både Barrett og Haas vektlegger at klimaendringer medfører større politiske og økonomiske utfordringer enn tidligere transnasjonale miljøproblemer som har blitt gjenstand for internasjonalt samarbeid, og betrakter dermed klimaregimet som en type avvikende case. Dette begrenser dermed muligheten til å trekke generelle slutninger basert på denne studien, men det er heller ikke formålet med teoretisk fortolkende case-studier. Det er derimot en målsetning at resultatene fra denne studien kan leses som anbefalinger for fremtidige klimaforhandlinger

Sub-millimeter Spectroscopy of Astrophysically Important Molecules and Ions: Metal Hydrides, Halides, and Cyanides

With the advent of SOFIA, Herschel, and SAFIR, new wavelength regions will become routinely accessible for astronomical spectroscopy, particularly at submm frequencies (0.5-1.1 THz). Molecular emission dominates the spectra of dense interstellar gas at these wavelengths. Because heterodyne detectors are major instruments of these missions, accurate knowledge of transition frequencies is crucial for their success. The Ziurys spectroscopy laboratory has been focusing on the measurement of the pure rotational transitions of astrophysically important molecules in the sub-mm regime. Of particular interest have been metal hydride species and their ions, as well as metal halides and cyanides. A new avenue of study has included metal bearing molecular ions

THE MILLIMETER/SUBMILLIMETER-WAVE SPECTRUM OF F2SO (~X1A′)

The millimeter/submillimeter spectrum of F$_2$SO (\~{X}$^1$A$'$) has been measured using direct absorption techniques in the frequency range 271 – 508 GHz. Thionyl fluoride was created in the process of searching for a number of metal-containing fluoride molecules. This species was serendipitously produced from SF$_6$ as the fluorine source with residual water in the presence of a DC discharge. Multiple rotational transitions in the range $J$ = 16 to $J$ = 30 were recorded, each consisting of a $c$-type asymmetric top pattern, due to the large dipole moment along the \^{c} molecular axis $\mu_c$ = 1.62 D. The data were analyzed using an asymmetric top Hamiltonian and rotational and centrifugal distortion constants were established. This work considerably expands the spectroscopic characterization of F$_2$SO. Previous microwave data consisted of measurements below 77 GHz