322 research outputs found
-hii: Modality meets exclusivity
No full textThis work examines the meaning of the Hindi particle ‘-hii’ and sheds new light on the link between modality and words like ‘only.’ Our two new judgment studies reveal that ‘-hii’ indicates exclusivity (like 'only,' and other similar lexical items) and also can associate with either the MIN or MAX of a scale of propositional alternatives. More specifically, the alternatives are ordered based on speaker conceptions of likelihood or of desirability, and which endpoint is felicitous with ‘-hii’ depends on which scale is made salient by the discourse context. Since existing analyses of 'only' and 'even' are insufficient for capturing the presuppositions of ‘-hii’ that are revealed by the experimental data, we draw on the recent theoretical literature on modality to map these ranking types of ‘-hii’ to epistemic, bouletic, and teleological modality types that form its core scalar felicity condition. Besides helping to formalize the varied types of speaker expectations needed by ‘-hii’, this move helps to explain some differences between the likelihood and desirability contexts' patterning of data in our experimental results.Paper presented at the Penn Linguistics Conference (PLC), March 20-22, 2015, and published in the Working Papers as part of the Proceedings of the 39th Annual Penn Linguistics Conference
Scaling up exclusive -hii
No full textThis dissertation explores the meaning of the Hindi particle -hii. The standard view is that -hii is equivalent to English only but has various other extraneous uses. I show that these varied uses can be unified as scalar meaning. This research provides the first set of empirical studies into the fine-grained scalar sensitivity of -hii and related particles. In Chapter 1, I introduce -hii by highlighting its similarities and differences with only and even. Chapters 2 through 6 are then devoted to exploring four aspects of the meaning of -hii. First I challenge the standard view of -hii by showing in Chapter 2 that speakers are sensitive to the felicity of -hii based on the scale in the context. In particular, -hii can select for the MAX of one scale type and MIN of another. Using Potts (2005), I assign these scalar meanings to the level of not-at-issue meaning, specifically as conventional implicature. I then show in Chapter 3 how -hii's upper-bounding effect is achieved with entailment-based scales, using the case of numerals. I furthermore show how -hii combines with the particle sirf, which is the Hindi counterpart of English only. In Chapter 4, I introduce the issue of -hii's interaction with negation, and use this to motivate a flexible meaning of -hii that can account for its uses in contexts where scalar orderings are absent. I discuss results of a judgment study showing that both a scalar and non-scalar reading are accessible to speakers when -hii interacts with negation, a problem first observed by Bhatt (1994). In Chapter 5, I discuss uses of -hii that reflect speaker certainty and degree intensification, by introducing data with adjectives and adverbs. I show how these cases are similar to polysemous intensifying particles in other languages -- Italian and Washo, (Beltrama & Bochnak (2015)), Marathi -c (Deo (2014)) and Russian sam (Goncharov (2013)). I demonstrate how these uses of -hii relate to a general association with scalar endpoints. I conclude in Chapter 6 and propose topics for continued investigation within this line of research.Ph.D.Includes bibliographical referencesby Vandana Baja
Science with an ngVLA: radio recombination lines from HII regions
No full textThe ngVLA will create a Galaxy-wide, volume-limited sample of HII regions;
solve some long standing problems in the physics of HII regions; and provide an
extinction-free star formation tracer in nearby galaxies.First author draf
Symptoms of Imminent Eclampsia Among Women Attending Care at Muhimbili National Hospital: A Case Refferent Study
No full textPreeclampsia affects about 5 to 10% of all pregnancies and eclamptic seizure is one of its serious complications. In many developing countries including Tanzania, maternal and perinatal mortality due to eclampsia are high. As yet, primary prevention of eclampsia is not possible since the causes are largely unknown. Headache, visual disturbance, abdominal pain, nausea, and vomiting have been reported by various studies to precede most eclamptic seizures; thus could be used to predict and therefore prevent some cases given the availability of magnesium sulphate. These symptoms however are also common in normal pregnancy and post delivery mothers due to physiological changes of pregnancy and common disease conditions that usually affect pregnant women in our settings. The present study evaluated the characteristics of symptoms that are consistent with imminence of eclampsia This was a case referent study in which 123 eclamptic and 123 non eclamptic mothers that best matched in terms of age, parity, gestation age and delivery were enrolled, making a total of 246 women. The presence and characteristics of headache, visual disturbance, abdominal pain, nausea, and vomiting were enquired. A 4 grade scale was used to grade the severity of headache. In the rest of symptoms, common presenting features were utilized. Headache was common in both groups but was more frequent in eclamptic than in referent group of women (88% vs. 43%, p <0.001). In eclamptic mothers headache was mainly severe, frontal and most of the seizures happened within one week of the onset of headache, as compared to referent women where headache was mostly mild and either frontal or generalized. Visual problems were significantly frequent in eclamptics than in referent women, (39% vs. 3% p<0.001). Of the eclamptic mothers who presented with visual problems, 45(94%) had blurring of vision, 32(67%) had blind spots, 10(21%) had photophobia and only 7(15%) had total blindness. A total of 47(98%) of eclamptic mothers developed seizures within 12hours of the onset of visual problems. The frequency of abdominal pain was not significantly different between eclamptic and referent mothers (47% vs.38% p=0.156), however upper quadrant abdominal pain was significantly reported in eclamptic than in referent group of women (36% vs.9%, p=0.001). There was no significant difference on the type of abdominal pain presented by both groups. Nausea was common in both eclamptics and referent group of women (60% vs. 54%, p=0.303). There was no difference on presentation with vomiting among eclamptic and referent women (62% vs. 68% p=0.516) and in both groups the type of vomiting was commonly non projectile. This study has revealed that headache, abdominal pain, nausea and vomiting are common to pregnancy whether or not complicated by preeclampsia/eclampsia. The characteristics of headache, visual disturbances and abdominal pain differ between eclamptics and women without preeclampsia/eclampsia. In a pre eclamptic woman, an onset of a severe frontal headache or upper quadrant abdominal pain would suggest an occurrence of seizures within one week. Visual disturbance is the most ominous sign as seizures ensue within 12 hours of its onset. Nausea and vomiting cannot be reliably used to predict clampsia.\u
H-alpha observations of Sh2-190, Sh2-222, Sh2-229, Sh2-236 HII regions
No full textH alpha spectral line (6563 angstrom) profiles of four northern HII regions in the our galaxy (Sh2-190, Sh2-222, Sh2-229, Sh2-236) have been obtained using DEFPOS spectrometer, located at coude focus of 150 cm RTT150 telescope at TUBITAK National Observatory (TUG, Antalya, Turkey). Observations were carried out at nights of 2015 December 24-27 with long exposure times ranging from 900s to 3600s. The LSR velocities and the linewidths (Full Width Half Maximum: FWHM) of the H alpha emission lines were found to be in the range of -45.46 kms(-1) to + 3.57 kms(-1) and 38.50 kms(-1) to 44.10 kms(-1), respectively. The Sh2-229 HII region is the faintest one (211.16 R), while the Sh2-236 HII region (IC410) is brightest source (535.75 R). The LSR velocity and the line width (FWHM) results of the DEFPOS/RTT150 system were compared with the data by several authors given in literature and results of DEFPOS data were found to be in good agreement with data given in literature
Ultracompact HII regions with extended emission: The complete view
No full text\ua9 2019 The Author(s). In this paper, we present the results of a morphological study performed on a sample of 28 ultracompact HII (UC HII) regions located near extended free-free emission, using radio continuum (RC) observations at 3.6 cm with the C and D Very Large Array (VLA) configurations, with the aim of determining a direct connection between them. By using previously published observations in B and D VLA configurations, we compiled a final catalogue of 21 UC HII regions directly connected with the surrounding extended emission (EE). The observed morphology of most of the UC HII regions in RC emission is irregular (single- or multipeaked sources) and resembles a classical bubble structure in the Galactic plane with well-defined cometary arcs. RC images superimposed on colour composite Spitzer images reinforce the assignations of direct connection by the spatial coincidence between the UC components and regions of saturated 24 μm emission. We also find that the presence of EE may be crucial to understand the observed infrared excess because an underestimation of ionizing Lyman photons was considered in previous works (e.g. Wood & Churchwell; Kurtz, Churchwell & Wood)
The impact of HII regions on Giant Molecular Cloud properties in nearby galaxies sampled by PHANGS ALMA and MUSE
No full textWe identify giant molecular clouds (GMCs) associated with HII regions for a
sample of 19 nearby galaxies using catalogs of GMCs and H regions released by
the PHANGS-ALMA and PHANGS-MUSE surveys, using the overlap of the CO and
H{\alpha} emission as the key criterion for physical association. We compare
the distributions of GMC and HII region properties for paired and non-paired
objects. We investigate correlations between GMC and HII region properties
among galaxies and across different galactic environments to determine whether
GMCs that are associated with HII regions have significantly distinct physical
properties to the parent GMC population. We identify trends between the
H{\alpha} luminosity of an HII region and the CO peak brightness and the
molecular mass of GMCs that we tentatively attribute to a direct physical
connection between the matched objects, and which arise independently of
underlying environmental variations of GMC and HII region properties within
galaxies. The study of the full sample nevertheless hides a large variability
galaxy by galaxy. Our results suggests that at the ~100 pc scales accessed by
the PHANGS-ALMA and PHANGS-MUSE data, pre-supernova feedback mechanisms in HII
regions have a subtle but measurable impact on the properties of the
surrounding molecular gas, as inferred from CO observations
Crystal structure of archaeal RNase HII: a homologue of human major RNase H
No full textAbstractBackground: RNases H are present in all organisms and cleave RNAs in RNA/DNA hybrids. There are two major types of RNases H that have little similarity in sequence, size and specificity. The structure of RNase HI, the smaller enzyme and most abundant in bacteria, has been extensively studied. However, no structural information is available for the larger RNase H, which is most abundant in eukaryotes and archaea. Mammalian RNase H participates in DNA replication, removal of the Okazaki fragments and possibly DNA repair.Results: The crystal structure of RNase HII from the hypothermophile Methanococcus jannaschii, which is homologous to mammalian RNase H, was solved using a multiwavelength anomalous dispersion (MAD) phasing method at 2 Å resolution. The structure contains two compact domains. Despite the absence of sequence similarity, the large N-terminal domain shares a similar fold with the RNase HI of bacteria. The active site of RNase HII contains three aspartates: Asp7, Asp112 and Asp149. The nucleotide-binding site is located in the cleft between the N-terminal and C-terminal domains.Conclusions: Despite a lack of any detectable similarity in primary structure, RNase HII shares a similar structural domain with RNase HI, suggesting that the two classes of RNases H have a common catalytic mechanism and possibly a common evolutionary origin. The involvement of the unique C-terminal domain in substrate recognition explains the different reaction specificity observed between the two classes of RNase H
Models of diffuse Hα in the interstellar medium : the relative contributions from in situ ionization and dust scattering
No full textJB acknowledges the support of an STFC studentship. LMH acknowledges support from the US National Science Foundation through award AST-1108911.Using three-dimensional Monte Carlo radiation transfer models of photoionization and dust scattering, we explore different components of the widespread diffuse Hα emission observed in the interstellar medium of the Milky Way and other galaxies. We investigate the relative contributions of Hα from recombination emission in ionized gas and Hα that originates in HII regions near the Galactic mid-plane and scatters off high-altitude dust in the diffuse interstellar medium. For the radiation transfer simulations, we consider two geometries for the interstellar medium: a three-dimensional fractal geometry that reproduces the average density structure inferred for hydrogen in the Milky Way, and a density structure from a magnetohydrodynamic simulation of a supernova-driven turbulent interstellar medium. Although some sight lines that are close to HII regions can be dominated by scattered light, overall we find that less than ~20 per cent of the total Hα intensity in our simulations can be attributed to dust scattering. Our findings on the relative contribution of scattered Hα are consistent with previous observational and theoretical analyses. We also investigate the relative contributions of dust scattering and in situ ionization of high-density dust clouds in the diffuse gas. Dust scattering in these partially ionized clouds contribute ~40 per cent to the total intensity of Hα.Peer reviewe
Low‐mass young stellar population and star formation history of the cluster IC 1805 in theW4 HII region
No full textInternational audienceW4 is a giant HII region ionized by the OB stars of the cluster IC 1805. The HII region/cluster complex has been a subject of numerous investigations as it is an excellent laboratory for studying the feedback effect of massive stars on the surrounding region. However, the low‐mass stellar content of the cluster IC 1805 remains poorly studied till now. With the aim to unravel the low‐mass stellar population of the cluster, we present the results of amultiwavelength study based on deep optical data obtained with the Canada‐France‐Hawaii Telescope, infrared data from Two Micron All Sky Survey and Spitzer Space Telescope and X‐ray data from Chandra Space Telescope. The present optical data set is complete enough to detect stars down to 0.2 M‐circle dot, which is the deepest optical observation so far for the cluster. We identified 384 candidate young stellar objects (YSOs; 101 Class I/II and 283 Class III) within the cluster using various colour‐colour and colour‐magnitude diagrams. We inferred the mean age of the identified YSOs to be similar to 2.5 Myr and mass in the range 0.3‐2.5 M‐circle dot. The mass function of our YSO sample has a power‐law index of ‐1.23 +/‐ 0.23, close to the Salpeter value (‐1.35), and consistent with those of other star‐forming complexes. We explored the disc evolution of the cluster members and found that the disc‐less sources are relatively older compared to the disc bearing YSO candidates. We examined the effect of high‐mass stars on the circumstellar discs and within uncertainties, the influence of massive stars on the disc fraction seems to be insignificant. We also studied the spatial correlation of the YSOs with the distribution of gas and dust of the complex to conclude that IC 1805 would have formed in a large filamentary cloud
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