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We present spectra of the 3.3 mum and 11.2 mum polycyclic aromatic hydrocarbon (PAH) features of a large number of stellar sources, planetary nebulae, reflection nebulae, H II regions, and galaxies, obtained with Infrared Space Observatory Short Wavelength Spectrometer. Clear variations are present in the profiles of these features. Most of the sources show a symmetric 3.3 mum feature peaking at similar to3.290 mum, while only very few show an asymmetric 3.3 mum feature peaking at a slightly longer wavelength. The profiles of the 11.2 mum feature are distinctly asymmetric. The majority of the sources has a 11.2 mum feature peaking between 11.20 and 11.24 mum, with a very steep blue rise and a low tail-to-top ratio. A few sources show a 11.2 mum feature with a peak position of similar to11.25 mum, a less steep blue rise, and a high tail-to-top ratio. The sources are classified independently on the basis of the 3.3 and 11.2 mum feature profiles and peak positions. Correlations between these classes and those based on the 6-9 mum features (Peeters et al.) are found. In particular, sources with the most common profiles in the 6-9 mum region also show the most common 3.3 and 11.2 mum feature profiles. However, the uncommon profiles do not correlate with each other. Also, these classifications depend on the type of object. In general, H II regions, nonisolated Herbig AeBe stars and young stellar objects show the same profiles for all 3-12 mum features. Many planetary nebulae and post-asymptotic giant branch stars show uncommon feature profiles. The three galaxies in our sample show the same profiles as the H II regions for all but the 11.2 mum feature, being similar to that of evolved stars. The observed pronounced contrast in the spectral variations for the CH modes (3.3 and 11.2 mum bands) versus the CC modes (6.2, 7.7, and 8.6 mum bands) is striking: the peak wavelengths of the features attributed to CC modes vary by similar to15-80 cm(-1), while for the CH modes the variations are similar to4-6.5 cm(-1). We summarize existing laboratory data and theoretical calculations of the modes emitting in the 3-12 mum region of PAH molecules and complexes. In contrast to the 6.2 and 7.7 mum components, which are attributed to PAH cations, the 3.3 mum feature appears to originate in neutral and/or negatively charged PAHs. We attribute the variations in peak position and profile of these IR emission features to the composition of the PAH family. The variations in FWHM of the 3.3 mum feature remains an enigma, while those of the 11.2 mum can be explained by anharmonicity and molecular structure. The possible origin of the observed contrast in profile variations between the CH modes and the CC modes is highlighted.

We report infrared spectral evidence of deuterated interstellar polycyclic aromatic hydrocarbons (PAHs). Two bands are detected in the infrared emission from the ionization bar in Orion at 4.4 and 4.65 � m. The one at 4.65 � m is present at the 4.4 � level, while the one at 4.4 � m is more tentative, with aequal to 1.9. An emission band at 4.65 � m is also detected in the infrared emission from M17 by Verstraete and coworkers at the 4.4 � level. These wavelengths are highly characteristic of C-D stretching modes of deuterated PAHs and fall in a featureless region oftheinterstellarspectrum.TheIRspectroscopicpropertiesofdeuteratedPAHsaresummarized,andanestimateof the deuterium fractionation between the aromatic and aliphatic carbons associated with the PAHs is given. High deuterium fractionation is implied; this is discussed in terms of interstellar PAH fractionation mechanisms. Subject headings: astrochemistry — infrared: ISM — ISM: abundances — ISM: molecules — line: identification — techniques: spectroscopic

Purpose. This study was conducted to evaluate the ability of sonography to visualize the ulnar nerve at Guyon's canal and the common pero- neal nerve dorsal to the fibular head and to test for correlations between nerve measurements and sub- ject characteristics. Methods. We used a 5-12-MHz linear-array trans- ducer in sonographic evaluation of 15 healthy adult volunteers. We evaluated the correlations between nerve diameters and surface areas and subject body mass index and height. We also tested for differences between nerve measurements in women and men and between nerve measurements from the left and right sides of the body. Results. Both nerves were visualized in all subjects. Subject height correlated significantly with the antero- posterior diameter of the right ulnar nerve. Body mass index correlated significantly with the surface area of both ulnar nerves, with the anteroposterior diameter of both ulnar nerves, with the transverse diameter of the left ulnar nerve, and with the trans- verse diameter of the right common peroneal nerve. There was a statistically significant difference in antero- posterior diameter of the left ulnar and left common peroneal nerves between women and men. There were no significant differences between left- and right-side measurements for the combined data from the entire group of subjects. Conclusions. A 5-12-MHz linear-array transducer readily allows for visualization of the ulnar nerve at Guyon's canal and the common peroneal nerve dor- sal to the fibular head. a 2004 Wiley Periodicals, Inc. J Clin Ultrasound 32:375-380, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.20054

Purpose Sonographic calculation of thyroid volume is used in the diagnosis and follow-up of thyroid diseases. Since the calculated volume of thyroid lobes is highly influenced by the longest (ie, craniocaudal) diameter, we examined whether using a curved-array transducer as opposed to a linear-array transducer to measure the craniocaudal diameter would reduce interobserver variation. Methods Three sonographers with different levels of expertise each used a 5–12-MHz linear-array transducer and a 2–5-MHz curved-array transducer to measure the craniocaudal diameter of both thyroid lobes of 25 healthy volunteers. On the basis of these measurements, thyroid lobe volumes were calculated. Single-factor analysis of variance was used to evaluate the interobserver variations between the measurements made by all 3 observers as well as between measurements taken by pairs of observers. A p value of less than 0.05 was considered significant. Results Using the linear-array transducer to measure the craniocaudal diameter resulted in significant interobserver variation in thyroid volume calculation (p = 0.02), whereas using the convex-array transducer did not. Using either transducer resulted in a highly significant interobserver variation in measurements of the craniocaudal diameter, although the variation was far more pronounced for measurements made with the linear-array transducer (p = 0.0005) than for those made with the curved-array transducer (p = 0.04). For both transducers, the interobserver variations were most pronounced between the most and the least experienced sonographers. Conclusions To avoid significant interobserver variation in calculating thyroid lobe volume, we recommend using a curved-array transducer to measure the craniocaudal diameter of the thyroid lobes. © 2003 Wiley Periodicals, Inc. J Clin Ultrasound 31:189–193, 2003

Objective: Ultrasound (US) measurement of thyroid volume is used in diagnosis and follow-up of patients with thyroid disease. We assessed a new formula and technique for thyroid volume calculation, based on an automatically continuous trace transverse surface area (aTSA) calculation, to ascertain where this technique could reduce inter-observer variation. Methods: Three observers with a different level of US expertise, using a 12–5 MHz linear transducer, examined 25 volunteers. Inter-observer variations were calculated for diameter measurements and for the thyroid lobe volume calculations using the single factor ANOVA method. Results: Using the new technique and formula, no statistically significant differences existed, in contradistinction to using the classical formula for an ellipsoid (P=0.02). Conclusion: When thyroid volume measurements are required, we recommend using a new method of thyroid volume calculation based on the use of an automatically calculated continuous trace aTSA measurement to avoid significant inter-observer variation in calculation of thyroid lobe volumes

We present the first detection of unidentified infrared (UIR) emission features at ~6.4 and 7.9 μm in the spectrum of the dusty WC8 Wolf-Rayet star WR 48a. Based on the H-deficient nature of WC stars, we attribute the emission features to large carbonaceous molecules or amorphous carbon dust grains in the circumstellar environment of WR 48a. The 6.4 μm feature resembles the emission feature seen toward H-deficient planetary nebulae (PNe), while the 7.9 μm profile resembles that of some PNe with H-deficient WC10 central stars. These similarities point toward a similar origin of the dust in these H-deficient environments and highlights the apparent sensitivity of the UIR bands to physical conditions. In the case of WR 48a and the [WC10] PNe, shock processing may play a major role in dust formation.

We present a detailed photoionization model of G29.96-0.02 (hereafter G29.96), one of the brightest Galactic Ultra Compact HII (UCHII) regions in the Galaxy. This source has been observed extensively at radio and infrared wavelengths. The most recent data include a complete ISO (SWS and LWS) spectrum, which displays a remarkable richness in atomic fine-structure lines. The number of observables is twice as much as the number available in previous studies. In addition, most atomic species are now observed in two ionization stages. The radio and infrared data on G29.96 are best reproduced using a nebular model with two density components: a diffuse (n_e~680cm-3) extended (~1 pc) component surrounding a compact (~0.1 pc) dense (n_e~57000cm-3) core. The properties of the ionizing star were derived using state-of-the-art stellar atmosphere models. CoStar models yield an effective temperature of \~30^{+2}_{-1} kK whereas more recent non-LTE line blanketed atmospheres with stellar winds indicate somewhat higher values, Teff~32--38 kK. This range in Teff is compatible with all observational constraints, including near-infrared photometry and bolometric luminosity. The range 33-36 kK is also compatible with the spectral type O5-O8 determined by Watson and Hanson (97) when recent downward revisions of the effective temperature scale of O stars are taken into account. The age of the ionizing star of G29.96 is found to be a few 10^6 yr, much older than the expected lifetime of UCHII regions. Accurate gas phase abundances are derived with the most robust results being Ne/S=7.5 and N/O=0.43 (1.3 and 3.5 times the solar values, respectively)., Accepted in Astronomy and Astrophysics

IR spectroscopy provides a valuable tool for the characterisation and identification of interstellar molecular species. Here, we present 6-9 mum spectra of a sample of reflection nebulae, HII regions, YSOs, evolved stars and galaxies that show strong unidentified infrared bands, obtained with the SWS spectrograph on board ISO. The IR emission features in this wavelength region show pronounced variations. 1) The 6.2 mum feature shifts from 6.22 to 6.3 mum and clearly shows profile variations. 2) The 7.7 mum complex is comprised of at least two subpeaks peaking at 7.6 and one longwards of 7.7 mum. In some cases the main peak can apparently shift up to 8 mum. Two sources do not exhibit a 7.7 mum complex but instead show a broad emission feature at 8.22 mum. 3) The 8.6 mum feature has a symmetric profile in all sources and some sources exhibit this band at slightly longer wavelengths. For the 6.2, 7.7 and 8.6 mum features, the sources have been classified independently based on their profile and peak position. The classes derived for these features are directly linked with each other. Sources with a 6.2 mum feature peaking at similar to6.22 mum exhibit a 7.7 mum complex dominated by the 7.6 mum component. In contrast, sources with a 6.2 mum profile peaking longwards of 6.24 mum show a 7.7 mum complex with a dominant peak longwards of 7.7 mum and a 8.6 mum feature shifted toward the red. Furthermore, the observed 6-9 mum spectrum depends on the type of object. All ISM-like sources and a few PNe and Post-AGB stars belong to the first group while isolated Herbig AeBe stars, a few Post-AGB stars and most PNe belong to the second group. We summarise existing laboratory data and theoretical quantum chemical calculations of the modes emitting in this wavelength region of PAH molecules. We discuss the variations in peak position and profile in view of the exact nature of the carrier. We attribute the observed 6.2 mum profile and peak position to the combined effect of a PAH family and anharmonicity with pure PAHs representing the 6.3 mum component and substituted/complexed PAHs representing the 6.2 mum component. The 7.6 mum component is well reproduced by both pure and substituted/complexed PAHs but the 7.8 mum component remains an enigma. In addition, the exact identification of the 8.22 mum feature remains unknown. The observed variations in the characteristics of the IR emission bands are linked to the local physical conditions. Possible formation and evolution processes that may influence the interstellar PAH class are highlighted.

The massive star forming region W49A represents one of the largest complexes of massive star formation present in the Milky Way and contains at least fifty young massive stars still enshrouded in their natal molecular cloud. We employ Spitzer/IRS spectral mapping observations of the northern part of W49A to investigate the mid-infrared (MIR) spatial appearance of the polycyclic aromatic hydrocarbon (PAH) bands, PAH plateau features, atomic lines and continuum emission. We examine the spatial variations of the MIR emission components in slices through two of the ultra compact-HII (UC-HII) regions. We find that the PAH bands reproduce known trends, with the caveat that the 6.2 $\mu$m PAH band seems to decouple from the other ionized PAH bands in some of the UC-HII regions -- an effect previously observed only in one other object: the giant star forming region N66 in the LMC. Furthermore, we compare the nature of the emission surrounding W49A to that of `diffuse' sightlines. It is found that the surrounding emission can be explained by line of sight emission, and does not represent true `diffuse' material. Additionally, we examine the MIR appearance of star formation on various scales from UC-HII regions to starburst galaxies, including a discussion of the fraction of PAH emission in the 8 $\mu$m IRAC filter. We find that the MIR appearance of W49A is that of a starburst on large scales yet its individual components are consistent with other galactic HII regions., Comment: 23 pages, 14 figures, ApJ accepted

Mid-infrared (MIR) quasar spectra exhibit a suite of emission features including high ionization coronal lines from the narrow line region (NLR) illuminated by the ionizing continuum, and hot dust features from grains, as well as polycyclic aromatic hydrocarbons (PAH) features from star formation in the host galaxy. Few features are detected in most spectra because of typically low signal-to-noise ratio (S/N) data. By generating spectral composites in three different luminosity bins from over 180 Spitzer Infrared Spectrograph (IRS) observations, we boost the S/N and reveal important features in the complex spectra. We detect high-ionization, forbidden emission lines in all templates, PAH features in all but the most luminous objects, and broad silicate and graphite features in emission whose strength increases relative to the continuum with luminosity. We find that the intrinsic quasar spectrum for all luminosity templates is consistent, and the differences in the spectra can be explained by host galaxy contamination in the lower luminosity templates. We also posit that star formation may be active in most quasar host galaxies, but the spectral features of star formation are only detectable if the quasar is faint., 4 pages, 2 figures, IAU Symposium #304 "Multiwavelength AGN Surveys and Studies"

Fullerenes are a particularly stable class of carbon molecules in the shape of a hollow sphere or ellipsoid that might be formed in the outflows of carbon stars. Once injected into the interstellar medium (ISM), these stable species survive and are thus likely to be widespread in the Galaxy where they contribute to interstellar extinction, heating processes, and complex chemical reactions. In recent years, the fullerene species C60 (and to a lesser extent C70) have been detected in a wide variety of circumstellar and interstellar environments showing that when conditions are favourable, fullerenes are formed efficiently. Fullerenes are the first and only large aromatics firmly identified in space. The detection of fullerenes is thus crucial to provide clues as to the key chemical pathways leading to the formation of large complex organic molecules in space, and offers a great diagnostic tool to describe the environment in which they reside. Since fullerenes share many physical properties with PAHs, understanding how fullerenes form, evolve and respond to their physical environment will yield important insights into one of the largest reservoirs of organic material in space. In spite of all these detections, many questions remain about precisely which members of the fullerene family are present in space, how they form and evolve, and what their excitation mechanism is. We present here an overview of what we know from astronomical observations of fullerenes in these different environments, and discuss current thinking about the excitation process. We highlight the various formation mechanisms that have been proposed, discuss the physical conditions conducive to the formation and/or detection of fullerenes in carbon stars, and their possible connection to PAHs, HACs and other dust features., Comment: 6 pages, 2 figures. Proceedings of "The Life Cycle of Dust in the Universe: Observations, Theory, and laboratory Experiments". Taipei, Taiwan 18-22 November 2013. Editors: A. Andersen, M. Baes, H. Gomez, C. Kemper, D. Watson

Mid-infrared (MIR) quasar spectra exhibit a suite of emission features including high ionization coronal lines from the narrow line region illuminated by the ionizing continuum, broad dust bumps from silicates and graphites, and polycyclic aromatic hydrocarbon (PAH) features from star formation in the host galaxy. However, in Spitzer Infared Spectrograph (IRS) data, few features are detected in most individual spectra because of typically low signal-to-noise ratios (S/N). By generating spectral composites from over 180 IRS observations of Sloan Digital Sky Survey broad-line quasars, we boost the S/N and reveal features in the complex spectra that are otherwise lost in the noise. In addition to an overall composite, we generate composites in three different luminosity bins that span the range of 5.6 micron luminosities of 10$^{40}$--10$^{46}$ (erg~s$^{-1}$). We detect the high-ionization, forbidden emission lines of [SIV], [OIV], and [NeV] 14 micron in all templates and PAH features in all but the most luminous template. Ratios of lines with a range of ionization potentials show no evidence for a strong difference in the shape of the 41--97 eV ionizing continuum over this range of luminosities. The scaling of the emission-line luminosities as a function of continuum luminosity is consistent with what is expected, and shows no indication of a ``disappearing narrow-line region.'' The broad 10 and 18 micron silicate features in emission increase in strength with increasing luminosity, and a broad 3--5 micron black body consistent with graphite emission at 750 K is evident in the highest luminosity template. We find that the intrinsic quasar continua for all luminosity templates are consistent; apparent differences arise primarily from host galaxy contamination most evident at low luminosity., 12 pages, 15 figures, Accepted to MNRAS

ISO has shown that the mid–IR spectra of almost all sources are dominated by narrow emission features collectively known as the UIR bands. These bands are carried by a family of polycyclic aromatic hydrocarbon molecules containing about 50 C-atoms. Other classes of molecules such as C-chains as well as non-aromatic groups attached to the PAHs are much less abundant. ISO has revealed that the UIR spectrum is incredibly rich with a large number of weaker features, subfeatures, and shoulders; many of which were not known before. Some examples and the new insights they can provide are described. A systematic study of this spectral structure may well allow us to considerably narrow down the composition of the family of PAHs responsible for the observed emission.

OBJECTIVE. In the assessment of thyroid volume with sonography (formula of in ellipsoid), a correction factor is used. Whereas previously 0.524 was used. the World Health Organization has recently changed (after the first review) this correction factor to 0.479. We compare volume measurement of the thyroid using different correction factors to automated volume measurement using MDCT, and we define an optimal correction factor in thyroid volume assessment. CONCLUSION. Acceptable correction factors are situated in the range of 0.494-4054. We propose a correction factor of 0.529 when using the ellipsoid formula.

(abridged)The focus of this work is to study mid-infrared point sources and the diffuse interstellar medium (ISM) in the low-metallicity (~0.2 solar) giant HII region N66 using the Spitzer Space Telescope's Infrared Spectrograph. We study 14 targeted infrared point sources as well as spectra of the diffuse ISM that is representative of both the photodissociation regions (PDRs) and the HII regions. Among the point source spectra, we spectroscopically confirm that the brightest mid-infrared point source is a massive embedded young stellar object, we detect silicates in emission associated with two young stellar clusters, and we observe spectral features of a known B[e] supergiant that are more commonly associated with Herbig Be stars. In the diffuse ISM, we provide additional evidence that the very small grain population is being photodestroyed in the hard radiation field. The 11.3 um PAH complex emission exhibits an unexplained centroid shift in both the point source and ISM spectra that should be investigated at higher signal-to-noise and resolution. Unlike studies of other regions, the 6.2 um and 7.7 um band fluxes are decoupled; the data points cover a large range of I7.7/I11.3 PAH ratio values within a narrow band of I6.2/I11.3 ratio values. Furthermore, there is a spread in PAH ionization, being more neutral in the dense PDR where the radiation field is relatively soft, but ionized in the diffuse ISM/PDR. By contrast, the PAH size distribution appears to be independent of local ionization state. Important to unresolved studies of extragalactic low-metallicity star-forming regions, we find that emission from the infrared-bright point sources accounts for only 20-35% of the PAH emission from the entire region. These results make a comparative dataset to other star-forming regions with similarly hard and strong radiation fields., ApJ, in press. ~60 pages, 18 figures

The spatial variations in polycyclic aromatic hydrocarbon (PAH) band intensities are normally attributed to the physical conditions of the emitting PAHs, however in recent years it has been suggested that such variations are caused mainly by extinction. To resolve this question, we have obtained near-infrared (NIR), mid-infrared (MIR), and radio observations of the compact H II region IRAS 12063-6259. We use these data to construct multiple independent extinction maps and also to measure the main PAH features (6.2, 7.7, 8.6, and 11.2 {$μ$}m) in the MIR. Three extinction maps are derived: the first using the NIR hydrogen lines and case B recombination theory; the second combining the NIR data with radio data; and the third making use of the Spitzer/IRS MIR observations to measure the 9.8 {$μ$}m silicate absorption feature using the Spoon method and PAHFIT (as the depth of this feature can be related to overall extinction). The silicate absorption over the bright, southern component of IRAS 12063-6259 is almost absent while the other methods find significant extinction. While such breakdowns of the relationship between the NIR extinction and the 9.8 {$μ$}m absorption have been observed in molecular clouds, they have never been observed for H II regions. We then compare the PAH intensity variations in the Spitzer/IRS data after dereddening to those found in the original data. It was found that in most cases, the PAH band intensity variations persist even after dereddening, implying that extinction is not the main cause of the PAH band intensity variations.

We performed a detailed spectroscopic analysis of the fullerene C6o-containing planetary nebula (PN) Lin49 in the Small Magellanic Cloud (SMC). Lin49 is a C-rich and metal- deficient PN (Z~0.0006) and its nebular abundances are in agreement with the AGB model for the initially 1.25Mʘ stars with the metallicity Z = 0.001 of Fishlock et al. (2014, [1]). By stellar absorption fitting with TLUSTY, we derived stellar abundances, effective temperature, and surface gravity. We constructed the photo-ionization model with CLOUDY in order to investigate physical conditions of Lin49. The model with the 0.005-0.1 μm radius graphite and a constant hydrogen density shell could not fit the ~1-5 μm SED owing to the strong near-IR excess. We propose that the near-IR excess indicates (1) the presence of extremely small carbon molecules or (2) the presence of high-density structure surrounding the central star.

We compare and analyze the Spitzer mid-infrared spectrum of three fullerene-rich planetary nebulae in the Milky Way and the Magellanic Clouds; Tc1, SMP SMC16, and SMP LMC56. The three planetary nebulae share many spectroscopic similarities. The strongest circumstellar emission bands correspond to the infrared active vibrational modes of the fullerene species C60 and little or no emission is present from Polycyclic Aromatic Hydrocarbons (PAHs). The strength of the fullerene bands in the three planetary nebulae is very similar, while the ratio of the [NeIII]15.5um/[NeII]12.8um fine structure lines, an indicator of the strength of the radiation field, is markedly different. This raises questions about their excitation mechanism and we compare the fullerene emission to fluorescent and thermal models. In addition, the spectra show other interesting and common features, most notably in the 6-9um region, where a broad plateau with substructure dominates the emission. These features have previously been associated with mixtures of aromatic/aliphatic hydrocarbon solids. We hypothesize on the origin of this band, which is likely related to the fullerene formation mechanism, and compare it with modeled Hydrogenated Amorphous Carbon that present emission in this region., Comment: 13 pages, 2 tables, 7 figures, Accepted for publication in ApJ

Fullerenes have recently been identified in space and they may play a significant role in the gas and dust budget of various astrophysical objects including planetary nebulae (PNe), reflection nebulae (RNe) and H II regions. The tenuous nature of the gas in these environments precludes the formation of fullerene materials following known vaporization or combustion synthesis routes even on astronomical timescales. We have studied the processing of hydrogenated amorphous carbon (a-C:H or HAC) nano-particles and their specific derivative structures, which we name "arophatics", in the circumstellar environments of young, carbon-rich PNe. We find that UV-irradiation of such particles can result in the formation of fullerenes, consistent with the known physical conditions in PNe and with available timescales., Accepted for publication in ApJ. Revised version after comments from the referee. Few references added. Calculation in Sec. 3 moved to the Appendix. Results unchanged. 9 pages, 4 figures, 1 table, 1 Appendix

Intractability in epilepsy is difficult to define, and little is known about its onset, course, and duration. We investigated these aspects (as well as the occurrence of intractability) during long-term follow-up in patients with epilepsy, focusing on possible explanations for the variation in time of onset and duration of intractability.After diagnosis, 453 patients with childhood-onset epilepsy had a 5-year follow-up with regular visits and data collection. Ten years later they received a questionnaire with items concerning epilepsy, which was completed by 413 patients resulting in a mean follow-up of 15 years. Intractability during the first 5 years was compared with that in the last year of follow-up. Intractability was defined as having no 3-month remission during a 1-year period despite adequate medical treatment.At least 12.1% of the cohort had a period of intractability during the 15-year follow-up, and 8.5% were intractable in the final year. Of the patients with idiopathic etiology 4.3% had a period of intractability versus 17.0% for those with cryptogenic, and 22.6% for those with remote symptomatic etiology (p0.001). Other risk factors at baseline were younger age at first seizure, generalized cryptogenic/symptomatic or localization-related symptomatic epilepsy, mental retardation, and febrile convulsions before enrollment. The cumulative risk of a period of intractability was 6.1% (95% confidence interval [CI] 3.7-8.5) at 2 years follow-up and 8.2% (95% CI 5.4-11.0) at 5 years. The mean time to onset of intractability during the first 5 years of follow-up was 1.6 (95% CI 1.3-2.0; median 1.0) years and the mean duration of intractability during these 5 years was 3.3 (95% CI 2.8-3.8; median 3.6) years. Fifteen patients were intractable only during the first 5 years of follow-up (group A), and 19 subjects were intractable both during the first 5 years and the last year of follow-up (group B). Compared with group A, group B had shorter remission and a longer time to intractability during the first 5 years and more were intractable in the fifth year of follow-up. Sixteen other patients had a late onset of intractability after 5 years of follow-up, sometimes after long periods of remission (group C). No significant differences in baseline characteristics were found among groups A, B, and C, but slightly more children in groups B and C became mentally retarded during the follow-up. In all groups, antiepileptic drugs were of little use in preventing and ending intractability.There is a large unpredictable variation in time of onset, course, and duration of intractability, with a higher chance of final intractability after a poor course during the first 5 years of follow-up. The natural course of epilepsy probably best explains the variable course of intractability. The effect of medication seems to be minor.

Epilepsy may have far-reaching consequences for patients, other than having seizures and medication. At 15 years after diagnosis, this study investigates health perception, restrictions due to epilepsy, living arrangements (including marital status and offspring), and the educational and occupational attainment of patients with childhood-onset epilepsy.A total of 453 patients with epilepsy had a 5-year follow-up since diagnosis with regular visits and data collection. Ten years later, a questionnaire addressing epilepsy was completed by 413 patients, resulting in a mean follow-up of 15 years. Subjects were compared with age peers of the Dutch population for each etiologic group separately, and also for subjects with/without a 5-year terminal remission regardless of treatment. Age-adjusted standardized incidence rates were calculated for each variable.Subjects with normal intelligence had a health perception comparable with that of the general population, but significantly more subjects without remission had a worse health perception, especially those still using medication. Restrictions and symptoms due to epilepsy were reported by 14% of the subjects, mainly by those without remission or with ongoing medication. The living arrangement of subjects with idiopathic or cryptogenic etiology was similar to that of Dutch persons of the same age (age peers). Subjects with remote symptomatic etiology less often lived independently or with a partner, and more frequently resided in an institution or living group for the disabled. Those with and without remission were more often part of another household, mainly due (in both groups) to having a remote symptomatic etiology. Rates of having a partner and offspring were significantly reduced only for subjects with remote symptomatic etiology. Fewer students with idiopathic/remote symptomatic etiology and students in remission followed higher vocational or scientific education. In these latter groups, the highest attained education of employees was lower than expected. The employment status of subjects with idiopathic or cryptogenic etiology was comparable with that of their Dutch age peers, but fewer subjects with remote symptomatic etiology were employed and more of them were part of the dependent population. However, for those in the labor force (employed/unemployed) all employment rates were ≥90%, even for those with remote symptomatic etiology. Nevertheless, fewer employees than expected had a higher vocational or scientific level of occupation, even those with idiopathic etiology and those in remission.Health perception, living arrangement, and socioeconomic status were influenced by epilepsy, comorbidities, or treatment, particularly for subjects with remote symptomatic etiology or no remission. The group in remission fared less well than expected, mainly due to the numbers of subjects with remote symptomatic etiology in this group. In line with others, we conclude that childhood-onset epilepsy is associated with lower educational attainment, even for subjects with idiopathic etiology and subjects in remission; probably related to this, their occupational level was also lower than expected.

The infrared spectra of many galactic and extragalactic objects are dominated by emission features at 3.3, 6.2, 7.7, 8.6 and 11.2 \mu m. The carriers of these features remained a mystery for almost a decade, hence the bands were dubbed the unidentified infrared (UIR) bands. Since the mid-80's, the UIR bands are generally attributed to the IR fluorescence of Polycyclic Aromatic Hydrocarbon molecules (PAHs) upon absorption of UV photons -- the PAH hypothesis. Here we review the progress made over the past 25 years in understanding the UIR bands and their carriers., Comment: 13 pages, 7 figures. To appear in the proceedings of IAU symposium 280 "The Molecular Universe"

Context. The circumstellar environment of evolved stars is generally rich in molecular gas and dust. Typically, the entire environment is either oxygen-rich or carbon-rich, depending on the evolution of the central star. Aims. In this paper we discuss three evolved disc sources with evidence of atypical emission lines in their infrared spectra. The stars were taken from a larger sample of post-AGB binaries for which we have Spitzer infrared spectra, characterised by the presence of a stable oxygen-rich circumbinary disc. Our previous studies have shown that the infrared spectra of post-AGB disc sources are dominated by silicate dust emission, often with an extremely high crystallinity fraction. However, the three sources described here are selected because they show a peculiar molecular chemistry. Methods. Using Spitzer infrared spectroscopy, we study in detail the peculiar mineralogy of the three sample stars. Using the observed emission features, we identify the different observed dust, molecular and gas species. Results. The infrared spectra show emission features due to various oxygen-rich dust components, as well as CO2 gas. All three sources show the strong infrared bands generally ascribed to polycyclic aromatic hydrocarbons. Furthermore, two sample sources show C60 fullerene bands. Conclusions. Even though the majority of post-AGB disc sources are dominated by silicate dust in their circumstellar environment, we do find evidence that, for some sources at least, additional processing must occur to explain the presence of large carbonaceous molecules. There is evidence that some of these sources are still oxygen-rich, which makes the detection of these molecules even more surprising., Comment: Accepted for publication in Astronomy and Astrophysics, 10 pages, 7 figures

Cosmic Fullerenes Since the discovery of the buckminsterfullerene C 60 in laboratory experiments, it has been speculated that fullerenes could form abundantly in carbon-rich evolved stars and, because of their stability, survive the harsh radiation field in the interstellar medium as a gas-phase species. Cami et al. (p. 1180 ; published online 22 July; see the Perspective by Ehrenfreund and Foing ) have detected large amounts of fullerenes in a peculiar planetary nebula with an extremely hydrogen-poor dust formation zone. Contrary to expectations, the fullerenes are not gaseous; they are cool, are in a neutral charge state, and represent about 1.5% of the available carbon.

To study the course and outcome of childhood-onset epilepsy during 15-year follow-up (FU).We extended FU in 413 of 494 children with new-onset epilepsy recruited in a previously described prospective hospital-based study by questionnaire.Mean FU was 14.8 years (range 11.6-17.5 years). Five-year terminal remission (TR) was reached by 71% of the cohort. Course during FU was favorable in 50%, improving in 29%, and poor or deteriorating in 16%. Mean duration of seizure activity was 6.0 years (range 0-21.5 years), strongly depending on etiology and epilepsy type. Duration was1 year in 25% of the cohort and exceeded 12 years in another 25%. Antiepileptic drugs (AEDs) were used by 86% during a mean of 7.4 years: one-third had their last seizure within 1 year of treatment, and one-third continued treatment at the end, although some had a 5-year TR. At last contact, 9% of the cohort was intractable. In multivariate analysis, predictors were nonidiopathic etiology, febrile seizures, no 3-month remission, and early intractability. Eighteen patients died; 17 had remote symptomatic etiology. Standardized mortality ratio for remote symptomatic etiology was 31.6 [95% confidence interval (CI) 18.4-50.6], versus 0.8 [95% CI 0.02-4.2] for idiopathic/cryptogenic etiology.In most children with newly diagnosed epilepsy, the long-term prognosis of epilepsy is favorable, and in particular, patients with idiopathic etiology will eventually reach remission. In contrast, epilepsy remains active in approximately 30% and becomes intractable in approximately 10%. AEDs probably do not influence epilepsy course; they merely suppress seizures. Mortality is significantly higher only in those with remote symptomatic etiology.

Context. Spectral features between about 15-20 mu m are commonly associated with polycyclic aromatic hydrocarbons (PAHs). With the NASA Spitzer Space Telescope these features are reported routinely, and as such, warrant a deeper molecular explanation.Aims. We aim to determine the characteristics of the group of carriers of the plateau and the distinct sub-features at 15.8, 16.4, 17.4, 17.8 and 18.9 mu m and to draw astronomical implications from these spectra.Methods. We analyse and interpret the spectra of 15 different sources using the NASA Ames PAH IR spectroscopic database.Results. The bands within the 15-20 mu m region show large variations. Except for the 16.4 mu m band, there is also no connection, both in band strength and feature classification, with the mid-IR PAH bands. Of the PAH spectra considered, only those from species containing pendent rings show one "common" characteristic: a band near the astronomical 16.4 mu m position. However, coupling with the carbon skeleton's core influences its precise position in the spectrum. Compact PAHs in the size range 50-130 carbon atoms, consistently show a strong band near the astronomical 17.4 mu m band position.Conclusions. The 15-20 mu m region is the transition zone from PAH nearest neighbour modes to full-skeleton modes. We conclude that a few individual PAHs dominate the astronomical PAH family when clear features are prominent. In the few cases of a broad plateau, the PAH family would be far richer. Although PAHs containing pendent rings showed promise explaining the astronomical 16.4 mu m band, coupling with the skeleton core and the inherent strong quartet mode expected around 13.5 mu m, make it a less viable candidate. The number of large PAHs in the database becomes a limitation in studying the emission between 15-20 mu m and longward. Computation of larger PAH spectra should therefore be stimulated, especially for understanding the forthcoming far-IR data expected from Herschel, SOFIA and ALMA.

We present a Spitzer Space Telescope spectroscopic study of a sample of 25 planetary nebulae in the Magellanic Clouds. The low-resolution modules are used to analyze the dust features present in the infrared spectra. This study complements a previous work by the same authors where the same sample was analyzed in terms of neon and sulfur abundances. Over half of the objects (14) show emission of polycyclic aromatic hydrocarbons, typical of carbon-rich dust environments. We compare the hydrocarbon emission in our objects to those of Galactic HII regions and planetary nebulae, and LMC/SMC HII regions. Amorphous silicates are seen in just two objects, enforcing the now well-known-fact that oxygen-rich dust is less common at low metallicities. Besides these common features, some planetary nebulae show very unusual dust. Nine objects show a strong silicon carbide feature at 11um and twelve of them show magnesium sulfide emission starting at 25um. The high percentage of spectra with silicon carbide in the Magellanic Clouds is not common. Two objects show a broad band which may be attributed to hydrogenated amorphous carbon and weak low-excitation atomic lines. It is likely that these nebulae are very young. The spectra of the remaining eight nebulae are dominated by the emission of fine-structure lines with a weak continuum due to thermal emission of dust, although in a few cases the S/N in the spectra is low, and weak dust features may not have been detected., 13 pages, 2 tables, 7 figures, Accepted for publication in ApJ

Astronomical mid-IR spectra show two minor PAH features at 5.25 and 5.7 $\mu$m (1905 and 1754 cm$^{\rm - 1}$) that hitherto have been little studied, but contain information about the astronomical PAH population that complements that of the major emission bands. Here we report a study involving both laboratory and theoretical analysis of the fundamentals of PAH spectroscopy that produce features in this region and use these to analyze the astronomical spectra. The ISO SWS spectra of fifteen objects showing these PAH features were considered for this study, of which four have sufficient S/N between 5 and 6 $\mu$m to allow for an in-depth analysis. All four astronomical spectra show similar peak positions and profiles. The 5.25 $\mu$m feature is peaked and asymmetric, while the 5.7 $\mu$m feature is broader and flatter. Detailed analysis of the laboratory spectra and quantum chemical calculations show that the astronomical 5.25 and 5.7 $\mu$m bands are a blend of combination, difference and overtone bands primarily involving CH stretching and CH in-plane and CH out-of-plane bending fundamental vibrations. The experimental and computational spectra show that, of all the hydrogen adjacency classes possible on PAHs, solo and duo hydrogens consistently produce prominent bands at the observed positions whereas quartet hydrogens do not. In all, this a study supports the picture that astronomical PAHs are large with compact, regular structures. From the coupling with primarily strong CH out-of-plane bending modes one might surmise that the 5.25 and 5.7 $\mu$m bands track the neutral PAH population. However, theory suggests the role of charge in these astronomical bands might also be important., Comment: Accepted ApJ, 40 pages in pre-print, 14 figures, two online

To show the importance of high-spatial resolution observations of HII regions when compared with observations obtained with larger apertures such as ISO, we present mid-infrared spectra of two Magellanic Cloud HII regions, N88A and N160A. We obtained mid-infrared (8-13 um), long-slit spectra with TIMMI2 on the ESO 3.6m telescope. These are combined with archival spectra obtained with the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope, and are compared with the low-spatial resolution ISO-SWS data. An inventory of the spectra in terms of atomic fine-structure lines and molecular bands is presented. Concerning N88A, an isolated HII region with no adjacent infrared sources, the observations indicate that the line fluxes observed by ISO-SWS and Spitzer-IRS come exclusively from the compact HII region of about 3 arcsec in diameter. This is not the case for N160A, which has a more complex morphology. We have spectroscopically isolated for the first time the individual contributions of the three components of N160A, two high-excitation blobs, A1 and A2, and the young stellar object N160A-IR. In addition, extended [SIV] emission is observed with TIMMI2 and is most likely associated with the central star cluster located between A1 and A2. We show the value of these high-spatial resolution data in determining source characteristics, such as the degree of ionization of each high-excitation blob or the bolometric luminosity of the YSO. This luminosity is about one order of magnitude lower than previously estimated. For each high-excitation blob, we also determine the electron density and the elemental abundances of Ne, S, and Ar., 13 pages, 8 figures, accepted for publication in A&A

A 63-year old woman was admitted to our hospital for neurological reevaluation and MR-imaging. She had unsuccessfully tried to commit suicide by methanol ingestion on at least two known occasions earlier in life. After the first attempt in 1985, she presented limited visual impairment, followed by a nearly total blindness after the second non-recent ingestion. Clinical examination revealed bipyramidal dysfunction and major visual impairment. MR-imaging was performed on a 1.5-T system. T1 weighted FFE-images in the transverse plane as well as T2-weighted images in the transverse and coronal plane, Flair and T1-weighted FFE-images post Gadolinium contrast administration were obtained. Diffusion weighted imaging (TR 3919 ms, Ted 95, EPI Factor 77) was performed using spin echo multislice single-shot echo-planar imaging (EPI) sequences and ADC map was calculated.

We present the results of a systematic study of mid-IR spectra of Galactic regions, Magellanic HII regions, and galaxies of various types (dwarf, spiral, starburst), observed by the satellites ISO and Spitzer. We study the relative variations of the 6.2, 7.7, 8.6 and 11.3 micron features inside spatially resolved objects (such as M82, M51, 30 Doradus, M17 and the Orion Bar), as well as among 90 integrated spectra of 50 objects. Our main results are that the 6.2, 7.7 and 8.6 micron bands are essentially tied together, while the ratios between these bands and the 11.3 micron band varies by one order of magnitude. This implies that the properties of the PAHs are remarkably universal throughout our sample, and that the relative variations of the band ratios are mainly controled by the fraction of ionized PAHs. In particular, we show that we can rule out both the modification of the PAH size distribution, and the mid-infrared extinction, as an explanation of these variations. Using a few well-studied Galactic regions (including the spectral image of the Orion Bar), we give an empirical relation between the I(6.2)/I(11.3) ratio and the ionization/recombination ratio G0/ne.Tgas^0.5, therefore providing a useful quantitative diagnostic tool of the physical conditions in the regions where the PAH emission originates. Finally, we discuss the physical interpretation of the I(6.2)/I(11.3) ratio, on galactic size scales., Comment: Accepted by the ApJ, 67 pages, 70 figures

We report new correlations between ratios of band intensities of the 15-20 {\mu}m emission bands of polycyclic aromatic hydrocarbons (PAHs) in a sample of fifty-seven sources observed with Spitzer/IRS. This sample includes Large Magellanic Cloud point sources from the SAGE-Spec survey, nearby galaxies from the SINGS survey, two Galactic ISM cirrus sources and the spectral maps of the Galactic reflection nebulae NGC 2023 and NGC 7023. We find that the 16.4, 17.4 and 17.8 {\mu}m band intensities are inter-correlated in all environments. In NGC 2023 and NGC 7023 these bands also correlate with the 11.0 and 12.7 {\mu}m band intensities. The 15.8 {\mu}m band correlates only with the 15-20 {\mu}m plateau and the 11.2 {\mu}m emission. We examine the spatial morphology of these bands and introduce radial cuts. We find that these bands can be spatially organized into three sets: the 12.7, 16.4 and 17.8 {\mu}m bands; the 11.2, 15.8 {\mu}m bands and the 15-18 {\mu}m plateau; and the 11.0 and 17.4 {\mu}m bands. We also find that the spatial distribution of the 12.7, 16.4 and 17.8 {\mu}m bands can be reconstructed by averaging the spatial distributions of the cationic 11.0 {\mu}m and neutral 11.2 {\mu}m bands. We conclude that the 17.4 {\mu}m band is dominated by cations, the 15.8 {\mu}m band by neutral species, and the 12.7, 16.4 and 17.8 {\mu}m bands by a combination of the two. These results highlight the importance of PAH ionization for spatially differentiating sub-populations by their 15-20 {\mu}m emission variability., Comment: 17 pages, 14 figures, Accepted for publication in ApJ

We present the results of a computational study to investigate the infrared spectroscopic properties of a large number of polycyclic aromatic hydrocarbon (PAH) molecules and their fully dehydrogenated counterparts. We constructed a database of fully optimized geometries for PAHs that is complete for eight or fewer fused benzene rings, thus containing 1550 PAHs and 805 fully dehydrogenated aromatics. A large fraction of the species in our database have clearly non-planar or curved geometries. For each species, we determined the frequencies and intensities of their normal modes using density functional theory calculations. Whereas most PAH spectra are fairly similar, the spectra of fully dehydrogenated aromatics are much more diverse. Nevertheless, these fully dehydrogenated species show characteristic emission features at 5.2??m, 5.5??m, and 10.6??m; at longer wavelengths, there is a forest of emission features in the 16-30??m range that appears as a structured continuum, but with a clear peak centered around 19??m. We searched for these features in Spitzer-IRS spectra of various positions in the reflection nebula NGC?7023. We find a weak emission feature at 10.68??m in all positions except that closest to the central star. We also find evidence for a weak 19??m feature at all positions that is not likely due to C60. We interpret these features as tentative evidence for the presence of a small population of fully dehydrogenated PAHs, and discuss our results in the framework of PAH photolysis and the formation of fullerenes.

Estimates of the incidence of arm swelling after axillary lymph node dissection for breast cancer range from 10 to 37%. Yet the subjective sensation of edema is described in at least 54% of patients. The purpose of this research was to examine the structural changes occurring in the subcutaneous tissue that might explain these subjective complaints using multiple imaging modalities. Two female cadavers with unilateral breast amputation and axillary dissection were studied. The dermal and subcutaneous layers of both arms were visualized with high frequency ultrasonography, and magnetic resonance imaging and spectroscopy (MRS), and tissue biopsies were taken for histological evaluation. On the operated side, ultrasound imaging showed a hyperechogenic subcutis and the fat-to-water relationship in adipose cells was higher as measured by MRS. Dissection of the arms revealed structural adipose tissue changes, which were confirmed by microscopic evaluation.

In order to show the importance of high spatial resolution observations of extra-galactic sources when compared to observations obtained with larger apertures such as ISO, we present N-band spectra (8-13 um) of some locations in three starburst galaxies. In particular, the two galactic nuclei of the spiral galaxy NGC3256, the compact IR supernebula in the dwarf galaxy IIZw40 and the two brightest IR knots in the central starburst of the WR galaxy He2-10. The spectra have been obtained with TIMMI2 on the ESO 3.6m telescope. An inventory of the spectra in terms of atomic fine-structure lines and molecular bands is presented. We show the great value of these high spatial resolution data at constraining properties such as the extinction in the mid-IR, metallicity or stellar content (age, IMF, etc.). Regarding this, we have constrained the stellar content of the IR compact knot in IIZw40 by using the mid-IR fine-structure lines and setting restrictions on the nebular geometry. Considering the PAH bands, we have constructed a new mid-/far-IR diagnostic diagram based on the 11.2 um PAH and continuum, accessible to ground-based observations. Finally, we find a dependence between the presence or non-presence of PAHs and the hardness of the radiation field as measured by the [SIV]/[NeII] ratio. In particular, sources with PAH emission have in general a [SIV]/[NeII] ratio < 0.35. We investigate possible origins for this relation and conclude that it does not necessarily imply PAH destruction, but could also be explained by the PAH-dust competition for FUV photons., 22 pages, 10 figures, accepted for publication in A&A

We present Spitzer high spectral resolution IRS spectroscopy of three positions in the carbon-rich outflow of post-AGB star HD 44179, better known as the Red Rectangle. Surprisingly, the spectra show some strong unknown mid-infrared resonances, in the 13-20 micron range. The shape and position of these resonances varies with position in the nebula, and are not correlated with the PAH features. We conclude these features are due to oxygen-rich minerals, located in a region which is believed to be predominantly carbon-rich. We provide possible explanations for the presence of oxygen-rich dust in the carbon-rich outflows. Simple Mg-Fe-oxides are suggested as carriers of these unidentified features., Comment: accepted by ApJL; 5 pages; 4 figures

An overview is given of ISO results on regions of high excitation ISM and gas, i.e. HII regions, the Galactic Centre and Supernovae Remnants. IR emission due to fine-structure lines, molecular hydrogen, silicates, polycyclic aromatic hydrocarbons and dust are summarised, their diagnostic capabilities illustrated and their implications highlighted., Comment: To be publised in the review book : "ISO science legacy - a compact review of ISO major achievements"

Previous reports have demonstrated the diagnostic usefulness of diffusion- and perfusion-weighted magnetic resonance imaging (MRI) in the evaluation of cerebral venous thrombosis. However, the explanations ascribed for the pathophysiologic mechanisms of venous stroke in these reports were conflicting. Earlier reports supported prominent vasogenic edema associated with mild cytotoxic edema as the potential pathophysiologic mechanism. More recently, a few reports have found cytotoxic edema as the cause for venous stroke. The purpose of this report is to review the pathogenesis of cerebral venous thrombosis after taking into consideration the results of MRI findings. We report two cases of cerebral venous infarction, which had worsening symptoms and signs that resolved after intravenous heparin therapy. In both cases, findings on diffusion-weighted and perfusion-weighted MRI images were compatible with vasogenic edema and viable neuronal tissue. Both the patients recovered without any significant residual sequel. We support the hypothesis that in the pathogenesis of venous stroke vasogenic edema is the initial event, which may or may not be followed by cytotoxic edema eventually evolving to an infarction.

Observations of infrared fine-structure lines provide direct information on the metallicity and ionization structure of HII regions and indirectly on the hardness of the radiation field ionizing these nebulae. We have analyzed a sample of Galactic and Magellanic Cloud HII regions observed by the Infrared Space Observatory (ISO) to examine the interplay between stellar content, metallicity and the ionization structure of HII regions. The observed [SIV]10.5/[SIII]18.7 mum and [NeIII]15.5/[NeII]12.8 mum line ratios are shown to be highly correlated over more than two orders of magnitude. We have compared the observed line ratios to the results of photoionization models using different stellar energy distributions. The derived characteristics of the ionizing star depend critically on the adopted stellar model as well as the (stellar) metallicity. We have compared the stellar effective temperatures derived from these model studies for a few well-studied HII regions with published direct spectroscopic determinations of the spectral type of the ionizing stars. This comparison supports our interpretation that stellar and nebular metallicity influences the observed infrared ionic line ratios. We can explain the observed increase in degree of ionization, as traced by the [SIV]\[SIII] and [NeIII]\[NeII] line ratios, by the hardening of the radiation field due to the decrease of metallicity. The implications of our results for the determination of the ages of starbursts in starburst galaxies are assessed., 9 pages; accepted for publication in A&A; figure 3 modified

A set of ISOPHOT spectra from a sample of H II regions in the Large Magellanic Cloud (LMC) is presented. In all the spectra, emission bands arising from Polycyclic Aromatic Hydrocarbons (PAHs) are clearly present. These features are observed to vary considerably in relative strength to each other from source to source and even within 30 Doradus. The LMC spectra have been compared with ISO-SWS spectra from Galactic H II regions and with the ISOCAM observation towards a quiescent molecular cloud in the SMC (Reach et al. 2000). A correlation is found between the I-7.7/I-11.2 versus I-6.2/I-11.2 and the I-8.6/I-11.2 versus I-6.2/I-11.2 ratios. A segregation between the sources in the different types of environment (Milky Way - LMC - SMC) is present. Furthermore, within the LMC observations, a clear distinction between 30 Doradus and non-30 Doradus pointings is found. We discuss the variations in the relative strength of the PAH features in view of the different physical environments and highlight the relation with the PAH/dust ratio and the extinction curve. We conclude that 1) the same conditions responsible for the observed trends in the relative PAH-feature strengths also affect the carrier of the 2175 Angstrom bump leading to the differences in strength of the latter, and 2) the molecular structure is the major cause of the observed variations in the relative strength of the PAH features. In the SMC and 30 Doradus compact PAH species dominate, while PAHs with an open, uneven structure are the dominant ones in Galactic H II regions and the non-30 Dor LMC sources.

Infrared spectra between 2.3 and 196 mum were taken towards a sample of 45 compact H II regions using the two spectrometers (SWS and LWS) on board ISO. The primary goal is to determine the distribution of element abundances in the Galaxy, although there are also many other uses of this database. The spectra contain a wealth of information on the ionized gas and the associated photodissociation regions through the atomic fine-structure lines and on the dust properties via the dust emission bands and the continuum. Significant variations are found from source to source in both spectral shape and content. The sample of H II regions spans a wide range in galactocentric distance (from 0 to 22 kpc) enabling to investigate the variations of the nebular properties across the Galactic plane. The observations and the data reduction are described in detail in the present paper. The ISO spectral catalogue of compact H II regions contains the combined SWS-LWS spectra for each of the sources, the fluxes of the atomic fine-structure lines and hydrogen recombination lines, and an inventory of the spectra in terms of molecular lines, dust and ice bands.

Infrared spectra of carbon-rich objects which have evolved off the asymptotic giant branch reveal a range of dust properties, including fullerenes, polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons, and several unidentified features, including the 21 um emission feature. To test for the presence of fullerenes, we used the position and width of the feature at 18.7-18.9 um and examined other features at 17.4 and 6-9 um. This method adds three new fullerene sources to the known sample, but it also calls into question three previous identifications. We confirm that the strong 11 um features seen in some sources arise primarily from SiC, which may exist as a coating around carbonaceous cores and result from photo-processing. Spectra showing the 21 um feature usually show the newly defined Class D PAH profile at 7-9 um. These spectra exhibit unusual PAH profiles at 11-14 um, with weak contributions at 12.7 um, which we define as Class D1, or show features shifted to ~11.4, 12.4, and 13.2 um, which we define as Class D2. Alkyne hydrocarbons match the 15.8 um feature associated with 21 um emission. Sources showing fullerene emission but no PAHs have blue colors in the optical, suggesting a clear line of sight to the central source. Spectra with 21 um features and Class D2 PAH emission also show photometric evidence for a relatively clear line of sight to the central source. The multiple associations of the 21 um feature to aliphatic hydrocarbons suggest that the carrier is related to this material in some way., 30 pages, 30 figures, ApJ, in press

Based on the ISO spectral catalogue of compact HII regions by Peeters et al. (2001), we present a first analysis of the hydrogen recombination and atomic fine-structure lines originated in the ionized gas. The sample consists of 34 HII regions located at galactocentric distances between Rgal = 0 and 15 kpc. The SWS HI recombination lines between 2 and 8 mum are used to estimate the extinction law at these wavelengths for 14 HII regions. An extinction in the K band between 0 and $\sim$ 3 mag. has been derived. The fine-structure lines of N, O, Ne, S and Ar are detected in most of the sources. Most of these elements are observed in two different ionization stages probing a range in ionization potential up to 41 eV. The ISO data, by itself or combined with radio data taken from the literature, is used to derive the elemental abundances relative to hydrogen. The present data thus allow us to describe for each source its elemental abundance, its state of ionization and to constrain the properties of the ionizing star(s)., Comment: Accepted in Astronomy and Astrophysics, 22 pages, 20 figures, 9 tables

We present 10-15 micron spectra of a sample of H II regions, YSOs and evolved stars that show strong unidentified infrared emission features, obtained with the ISO/SWS spectrograph on-board ISO. These spectra reveal a plethora of emission features with bands at 11.0, 11.2, 12.0, 12.7, 13.5 and 14.2 micron. These features are observed to vary considerably in relative strength to each-other from source to source. In particular, the 10-15 micron spectra of the evolved stars are dominated by the 11.2 micron band while for H II regions the 12.7 is typically as strong as the 11.2 micron band. Analysing the ISO data we find a good correlation between the 11.2 micron band and the 3.3 micron band, and between the 12.7 micron and the 6.2 micron band. There is also a correlation between the ratio of the UIR bands to the total dust emission and the 12.7 over 11.2 micron ratio. Bands in the 10-15 micron spectral region are due to CH out-of-plane (OOP) bending modes of polycyclic aromatic hydrocarbons (PAHs). We summarise existing laboratory data and theoretical quantum chemical calculations of these modes for neutral and cationic PAHs. Due to mode coupling, the exact peak position of these bands depends on the number of adjacent CH groups and hence the observed interstellar 10-15 micron spectra can be used to determine the molecular structure of the interstellar PAHs emitting in the different regions. We conclude that evolved stars predominantly inject compact ~100-200 C-atom PAHs into the ISM where they are subsequently processed, resulting in more open and uneven PAH structures., 14 pages, 9 figures, accepted for A&A

As a result of an error at the Publisher, problems occurred in the presentation of Figures 4, 7, and 8. Figure 4 was printed without the mid-IR spectral data for the CH out-of-plane bending vibrations. The figure is printed here in its entirety. The example portions of online Figure sets 7 and 8 were presented in print in a low-resolution format. Similarly, the figure sets were presented online in low resolution and each part of the set was presented separately. The example portions of these figure sets are presented below as intended, and the online sets for Figures 7 and 8 are available online in higher resolution, arranged in a grid. IOP Publishing sincerely regrets these errors.