Development of a Web-based software tool for predicting the occurrence and effect of air pollutants inside museum buildings

22-27 September 200

The z=0.8596 Damped Lyman Alpha Absorbing Galaxy Toward PKS 0454+039

We present {\it Hubble Space Telescope} and ground--based data on the $z_{abs}=0.8596$ metal line absorption system along the line of sight to PKS 0454+0356. The system is a moderate redshift damped Lyman alpha system, with ${\rm N(HI)}=(5.7\pm0.3)\times10^{20}$~cm$^{-2}$ as measured from the {\it Faint Object Spectrograph} spectrum. We also present ground--based images which we use to identify the galaxy which most probably gives rise to the damped system; the most likely candidate is relatively underluminous by QSO absorber standards ($M_B \sim -19.0$ for $q_0=0.5$ and $H_0=50$ \kms Mpc$^{-1}$), and lies $\sim 8.5h^{-1}$ kpc in projection from the QSO sightline. Ground--based measurements of Zn~II, Cr~II, and Fe~II absorption lines from this system allow us to infer abundances of [Zn/H]=$-1.1$, [Cr/H]=$-1.2$, and [Fe/H]=$-1.2$, indicating overall metallicity similar to damped systems at $z >2$, and that the depletion of Cr and Fe onto dust grains may be even {\it less} important than in many of the high redshift systems of comparable metallicity. Limits previously placed on the 21-cm optical depth in the $z=0.8596$ system, together with our new N(H~I) measurement, suggest a very high spin temperature for the H~I, $T_S >> 580$ K.Comment: changed uuencode header to produce .Z file so that unix uncompress command will work without modifying file nam

"This awesome field"; a history of United States nuclear testing and its influence on nuclear thought, 1945-1963

The history of U. S. nuclear testing between 1945 and 1963 is not only a vivid and exciting story but also one of profound historical importance. It is the story of trailblazing scientific progress; improvement and miniaturization of weapons of mass destruction; accidents and affected populations and radiological contamination; and politics, posturing, and diplomacy. The normalisation of the testing of nuclear weapons was not a process that inevitably occurred in the aftermath of Hiroshima and Nagasaki. But rather there was a very real discourse within and among the American political and public spheres regarding nuclear testing, and ultimately it was a victory for those who argued in favor of national security over diplomatic and environmental costs that normalized nuclear weapons tests. The testing of nuclear weapons that defined the course and consequence of the Cold War was itself a crucial dimension to that narrative. But, above all else, the story of nuclear testing is one in which the central question – why conduct nuclear tests? – was fully debated among American politicians, generals and scientists. It is the examination of this question, beginning with the road to “normalisation” and later “denormalisation” of nuclear testing, leading to the Limited Nuclear Test Ban Treaty, in 1963, that this thesis is dedicated. As states continue to pursue nuclear weaponry, nuclear testing remains an important political issue in the twenty-first century, and the study of its history is vital

UV Interstellar Absorption Lines towards the Starburst Dwarf Galaxy NGC 1705

Archival Goddard High Resolution Spectrograph low-resolution spectra of NGC 1705, with wavelength ranges 1170.3 to 1461.7 A and 1453.5 to 1740.1 A and a velocity resolution of about 100 km\s, have been used to derive the velocity structure and equivalent widths of the absorption lines of Si II 1190.42, 1260.42, 1304.37 and 1526.71 A, S II 1253 , Al II 1670.79 Aand Fe II 1608.45 A in this sightline. Three relatively narrow absorption components are seen at LSR velocities --20 km/s, 260 km/sand 540 km/s. Arguments are presented to show these absorption features are interstellar rather than stellar in origin based on a comparison with the C III 1175.7 A absorption feature. We identify the --20 km/s component with Milky Way disk/halo gas and the 260 km/s component with an isolated high-velocity cloud HVC 487. This small HVC is located about 10 degrees from the H I gas which envelops the Magellanic Clouds and the Magellanic Stream (MS). The (Si/H) ratio for this HVC is > 0.6 (Si/H)solar which together with velocity agreement, suggests association with the Magellanic Cloud and MS gas. H-alpha emission line kinematics of NGC 1705 show the presence of a kpc-scale expanding supershell of ionized gas centered on the central nucleus with a blue-shifted emission component at 540 km/s (Meurer et al. 1992). We identify the 540 km/s absorption component seen in the GHRS spectra with the front side of this expanding, ionized supershell. The most striking feature of this component is strong Si II and Al II absorption but weak Fe II 1608 A absorption. The low Fe II column density derived is most likely intrinsic since it cannot be accounted for by ionization corrections or dust depletion. Due to their shallow gravitational potential wells, dwarf galaxies have small gravitational binding energies and are vulnerable to largeComment: 15 pages, LaTEX, 1 figure. Accepted for publication in Astrophysical Journal Letter

The Physical Characteristics of the Small-Scale Interstellar Structure towards Mu Crucis

We present HST/GHRS echelle observations of multiple interstellar lines of CI, MgI, CrII, and ZnII towards both stars in the mu Cru binary system. Despite large differences in the profiles of the neutral species, no significant variations between the stars are seen in the CrII and ZnII line profiles. In particular, the ZnII absorption observed at -8.6 km/sec towards mu Cru is constant despite greatly enhanced columns of the neutral species at this velocity towards mu^1 Cru. An analysis of the fine-structure excitation of CI in this cloud implies that the density is n_H < 250 cm^{-3}. From the lack of variation in the (optical) NaI D2 line profiles towards mu^1 and mu^2 Cru in spectra taken 21 months apart, we can place a lower limit to the size of the structures of ~10 AU. These results are discussed in the context of recent radio and optical studies of apparently pervasive high density small-scale interstellar structure.Comment: 10 pages, 2 figures, to appear in the Astrophysical Journal (Letters

Possible Detection of OVI from the LMC Superbubble N70

We present FUSE observations toward four stars in the LMC superbubble N70 and compare these spectra to those of four comparison targets located in nearby field and diffuse regions. The N70 sight lines show OVI 1032 absorption that is consistently stronger than the comparison sight lines by ~60%. We attribute the excess column density (logN_OVI=14.03 cm^-2) to hot gas within N70, potentially the first detection of OVI associated with a superbubble. In a survey of 12 LMC sight lines, Howk et al. (2002a) concluded that there was no correlation between ISM morphology and N_OVI. We present a reanalysis of their measurements combined with our own and find a clear difference between the superbubble and field samples. The five superbubbles probed to date with FUSE show a consistently higher mean N_OVI than the 12 non-superbubble sight lines, though both samples show equivalent scatter from halo variability. Possible ionization mechanisms for N70 are discussed, and we conclude that the observed OVI could be the product of thermal conduction at the interface between the hot, X-ray emitting gas inside the superbubble and the cooler, photoionized material making up the shell seen prominently in Halpha. We calculate the total hydrogen density n_H implied by our OVI measurements and find a value consistent with expectations. Finally, we discuss emission-line observations of OVI from N70.Comment: 9 pages in emulateapj style. Accepted to Ap

Pollen dimorphism and dioecy in Vitis aestivalis

Problems of low production and sterile pollen in varieties of Vitis vinifera may be tracable to their ancestral relations with dioecious wild grapes.Like V. riparia, the wild summer grape V. aestivalis has dimorphic male and female flowers; but unlike V. riparia it also has dimorphic pollen grains with the pollen from the female flower being significantly smaller.It seems fairly certain that V. aestivalis is truly dioecious

A numerical model for predicting the time for crack initiation in wood panel paintings under low-cycle environmentally induced fatigue

Determining the storage and display conditions for historical panel (wood) paintings requires a balance between ensuring the painting's preservation whilst also considering the energy consumption associated with climate control. The latter has become very important due to the need to lower the carbon footprint of museums and historical houses. In order to address this need, we have developed numerical models based on finite element analysis to simulate the initiation of two types of potential damage in panel paintings, namely interfacial and channelling cracks in the oil paint layer, under cyclically varying relative humidity. These models are based on our case study at Knole House (National Trust), Kent. Using known data for the past environment in which the paintings within the Brown Gallery at Knole House have been exposed, the ambient RH variation was approximated by three cycles, i.e., annual, biannual, and monthly varying cycles. Four RH cases, one containing all three cycles and each of the other three cases containing just two of the three cycles, were applied as boundary conditions to simplified geometries of the panel paintings in an effort to investigate the effects of the frequency and the amplitude of the variation on the possibility of cracking in the painting. The models need several material parameters as input which are not all available. Therefore, the study also includes some parametric studies to determine possible variations in the crack initiation. According to the model predictions, the channelling crack initiates slightly earlier than the interfacial crack. The crack initiation time in an uncontrolled environment (containing all three RH cycles) predicted by the model is approximately 120 years which empirically is a realistic estimate. Furthermore, the annual RH cycle (high amplitude and low frequency) has the most significant effect on the crack initiation. By removing the annual variation from the RH cycle, the initiation of both channelling and interfacial cracks can be postponed significantly, from approximately 120 years to over 400 years

Atomic and Molecular Interstellar Absorption Lines toward the High Galactic Latitude Stars HD 141569 and HD 157841 at Ultra-High Resolution

We present ultra-high-resolution (0.32 km s-1) spectra obtained with the 3.9 m Anglo-Australian Telescope (AAT) and Ultra-High-Resolution Facility (UHRF) of interstellar Na I D1, Na I D2, Ca II K, K I, and CH absorption toward two high Galactic latitude stars HD 141569 and HD 157841. We have compared our data with 21 cm observations obtained from the Leiden/Dwingeloo H I survey. We derive the velocity structure and column densities of the clouds represented by the various components and identify the clouds with ISM structures seen in the region at other wavelengths. We further derive abundances, linear depletions, and H2 fractional abundances for these clouds wherever possible. Both stars are located in regions of IRAS 100 μm emission associated with high Galactic latitude molecular clouds (HLCs): HD 141569 lies, in projection, close to MBM 37 and the Lynds dark cloud L134N, whereas HD 157841 is in the vicinity of the MBM 151. Toward HD 141569 we detect two components in our UHRF spectra: a weak, broad b = 4.5 km s-1 component at -15 km s-1, seen only in Ca II K absorption, and another component at 0 km s-1, seen in Na I D1, Na I D2, Ca II K, K I, and CH absorption. The cloud represented by the -15 km s-1 component is warm and may be located in a region close to the star. The cloud represented by the 0 km s-1 component has a Ca linear depletion δ(Ca) = 1.4 × 10-4 and shows evidence for the presence of dust, consistent with strong 100 μm emission seen in this region. The H2 fractional abundance f(H2) derived for this cloud is 0.4, which is typically what is observed toward HLCs. We conclude that this 0 km s-1 cloud is associated with MBM 37 and L134N based on the presence of dust and molecular gas (CH) and good velocity agreement with CO emission from these two clouds. This places HD 141569 beyond MBM 37 and L134N, which are estimated to be at ≈ 110 pc. In the case of the HD 157841 sight line, a total of six components are seen on our UHRF spectra in Na I D1, Na I D2, Ca II K, K I, and CH absorption. Two of these six components are seen only in a single species. The cloud represented by the components at 1.85 km s-1 has a Ca linear depletion δ(Ca) = 2.8 × 10-4, indicating the presence of dust. The f(H2) derived for this cloud is 0.45, and there is good velocity agreement with CO emission from MBM 151. To the best of our knowledge, this 1.85 km s-1 component toward HD 157841 is the first one found to have relative line widths that are consistent with pure thermal broadening only. We associate the 1.85 km s-1 cloud seen in our UHRF spectra with MBM 151 and conclude that HD 157841 must lie beyond ~200 pc, the estimated distance to MBM 151