bluuebunny/crossref_metadata_2025 huggingface dataset:
Syllabic weight and syllabic duration: a correlation between phonology and phonetics
Authors: Duanmu San
Published: October 2008

This paper explores a correlation between phonology and phonetics. It first reviews a phonological analysis that proposes that all full Mandarin rhymes are heavy and that all Shanghai rhymes are underlyingly light. Then it reports a small phonetic experiment that attempts to determine whether there is a phonetic correlate for the phonological claim. Four Mandarin speakers and five Shanghai speakers were recorded, each reading five sentences four times at normal speed. Average syllable durations were determined. It was found that the average syllable duration in Mandarin was 215 ms and that in Shanghai was 162 ms. Statistics show that the durational difference is significant. The result thus agrees with the phonological analysis. Implications and limitations of the present study will be discussed.
On the non-universality of tonal association ‘conventions’: evidence from Ciyao
Authors: Hyman Larry M. , Ngunga Armindo
Published: October 2008

One of the major aims of linguistic theory is to determine what is universalvs. language-specific within grammatical systems. In phonology, for example, a number of universals have been proposed and incorporated into the various subtheories that deal with segmental and prosodic aspects of sound systems. In his original autosegmental theory, for instance, Goldsmith (1976) provided a formalism and a set of principles embodying a number of universal claims about how different tiers may link to each other. Most of the support for this theory came from the study of tone: tones (Ts) were said to reside on separate ‘tiers’ joined by association lines to their respective tone-bearing units (TBUs).
Laryngeal features in Athapaskan languages
Authors: Rice Keren
Published: October 2008

In a typical Athapaskan language, consonants divide into three manners of articulation, stops/affricates, fricatives and sonorants. There are generally three major laryngeal classes in the stops/affricates, two in the fricatives and a single class in the sonorants. In this paper, I examine how laryngeal oppositions in stops/affricates and fricatives are best characterised. I argue in §§ 2—7 that stops/affricates (henceforth stops) are phonologically voiceless unaspirated, aspirated and glottalised, while fricatives exhibit a voiced-voiceless distinction. These classes do not account for all laryngeal interactions, however; evidence exists that aspiration and voicing cross-classify the stops and fricatives, with aspiration being necessary for fricatives and voicing for stops in late rules of the phonology; this is the topic of §§8-9. In addition, evidence suggests that while stops/affricates form a single class underlyingly, they are distinct at a late level. Implications of the analysis are discussed in §§10—11. Processes involving laryngeal features suggest a two-level model of phonology in which contrastive features are present underlyingly and predictable features are added postlexically for reasons of phonetic implementation. The absence of predictable features underlyingly argues against recent work that suggests that such features may be present at this level (e.g. Steriade 1992a, b, 1993b); their postlexical presence argues for a model in which the postlexical phonology is identifiable as the phonetic implementation component of the grammar (e.g. Mohanan 1986; see also Cohn 1993).
Phantom consonants in Basaa
Authors: Schmidt Deborah
Published: October 2008

Basaa, a zone A Bantu language spoken in Cameroon, is only one among many genetically unrelated languages for which the positing of phonetically null phantom consonants facilitates a phonological account of certain otherwise unexpected surface forms encountered in derivational paradigms. Clements & Keyser (1983), Marlett & Stemberger (1983), Keyser & Kiparsky (1984), Crowhurst (1988) and Hualde (1992) propose that phantom consonants exist in Turkish, Seri, French, Finnish, Southern Paiute and Aranese Gascon, for example, syllabifying as onsets or codas where appropriate and in certain cases inducing the gemination of an adjacent consonantal segment or the lengthening of a preceding tautosyllabic vowel, as we shall see takes place in Basaa.
The OCP, Prosodic Morphology and Sonoran Spanish diminutives: a reply to Crowhurst
Authors: Harris James
Published: October 2008

Megan Crowhurst's ‘Diminutives and augmentatives in Mexican Spanish: a prosodic analysis’ (1992, henceforth CRO) takes a fresh look at the thorny problem of explicating the distribution of the allomorphs -itV and -(e)citV of the Spanish diminutive suffix. CRO has conspicuous virtues. Among them is the limitation of data to a single dialect, namely Sonoran, of northern Mexico. This narrow focus is insurance against inadvertently mixing incompatible data, a special risk posed by the considerable dialect variability of productive diminutivisation. At the same time, CRO broadens its data base by taking into account the partial parallelism between diminutive -itV/-(e)citV and augmentative -otV/-(e)sotV.
Gestural representation and Lexical Phonology
Authors: McMahon April , Foulkes Paul , Tollfree Laura
Published: October 2008

Recent work on Articulatory Phonology (Browman & Goldstein 1986, 1989, 1991, 1992a, b) raises a number of questions, specifically involving the phonetics–phonology ‘interface’. One advantage of using Articulatory Phonology (henceforth ArtP), with its basic units of abstract gestures based on articulatory movements, is its ability to link phenomena previously seen as phonological to those which are conventionally described as allophonic, or even lower-level phonetic effects, since ‘gestures are... useful primitives for characterising phonological patterns as well as for analysing the activity of the vocal tract articulators’ (Browman & Goldstein 1991: 313). If both phonetics and phonology could ultimately be cast entirely in gestural terms, the phonetics–phonology interface might effectively cease to exist, at least in terms of units of analysis.
Stefan George and phonological theory
Authors: Ramer Alexis Manaster
Published: October 2008

Ever since Baudouin de Courtenay (e.g. 1917 [1990: 500]), the founder of phonology, it has been customary for every new phonological theory to make claims about the particular level(s) at which rules of versification may refer to phonological representations. Baudouin himself, for example, took rhyming to be evidence of phonemic identity. The birth of generative phonology thus led to a series of claims that rules of versification may have access to underlying representations – or to various intermediate levels of representation more shallow than the underlying but still deeper than phonemic. Starting with Zeps (1963) and for the next twenty-odd years a certain number of such arguments have been published, and it appears that their validity is widely assumed in the field, as reflected in such survey articles as O'Connor (1982: 155–156) and Hayes (1988: 228–229). Presumably it is precisely the widespread acceptance of these arguments that explains the relative lull in the debate recently (but see Malone 1982,1983, 1988a, b).
A unified account of Choctaw intensives
Authors: Ulrich Charles H.
Published: October 2008

Choctaw verbs form intensives by a complex procedure of (apparent) infixation, gemination and accentuation. Verbs of all shapes have two distinct intensive forms, which Ulrich (1986) distinguishes as they-grade (involving a geminateyy) and the g-grade (involving gemination of a stem consonant or a falling tone). Lombardi & McCarthy (1991) analyse Choctaw intensives in terms of the theory of prosodic circumscription (McCarthy & Prince 1990). Hammond (1993) gives an alternative analysis within the same theory. While insightful in certain respects, these analyses fail to account for the full range of Choctaw intensives, instead generating a single intensive for any verb. In the present paper, I propose a unified analysis of Choctaw intensives, with two, minimally different, procedures for generating the two intensives of any verb.
A Phase Window Framework for Articulatory Timing
Authors: Byrd Dani
Published: October 2008

One of the most significant challenges in the study of speech production is to acquire a theoretical understanding of how speakers coordinate articulatory movements. A variety of work has demonstrated that articulatory, prosodic and extralinguistic factors all influence speech timing in a complex and interactive way. Models such as Articulatory Phonology that stipulate the relative timing of articulatory units must be revised to allow for this variability. Such a revision is outlined below.

The following work should be viewed as a presentation of a new framework for conceptualising articulatory timing. This approach, meant to be programmatic rather than conclusive, is productive if it motivates research that might not otherwise have been undertaken. §1 overviews Articulatory Phonology. The implementation of articulatory timing in terms of phasing relations is discussed. Speech production data bearing on timing variability are discussed in §2. §3 argues for an alternative to Articulatory Phonology's current rule-based approach to intergestural timing that can allow for linguistic and extralinguistic variables to systematically influence phasing relations. §3.2 introduces the PHASE WINDOW framework, which allows the degree of articulatory overlap between linguistic gestures to vary within a constrained range. Finally, §4 concerns the relation of intergestural timing to the postulation of the segment as a primitive unit in phonology. It is hypothesised that certain intergestural timing relations are stable and lexically specified. Gestures whose coordination is constrained by lexical PHASE WINDOWS seem to bear a close relation to those conglomerates of gestures that constitute what is traditionally considered to be a segment.
Vowel raising in Basaa: a synchronic chain shift
Authors: Schmidt Deborah Schlindwein
Published: October 2008

Like many of the zone A Bantu languages of western equatorial Africa, Basaa, which is spoken over a large area to the north-east and east of Douala, Cameroon, shows an inventory of seven surface vowels (Guthrie 1953). The Basaa forms cited in this article, all of which are found in the comprehensive Dictionnaire Basaa-Français (Lemb & de Gastines 1973), are transcribed using the vowel symbols in (1):

These vowel symbols differ from those used by Guthrie only in that the hooks are eliminated from underneath his [i] and [u] and the dots are eliminated from underneath his [???] and [???]. I assume for these vowels the characteristics indicated in (1), where non-parenthesised feature specifications are a property of surface phonological representation and parenthesised feature specifications are default phonetic values. Following Hyman's (1988) analysis of Esimbi, another Cameroonian language containing these vowels in its inventory, I take [E] and [ɔ] to be low.

The verb roots in (2) contain instances of each of the seven surface vowels of Basaa:

Though bare verb roots may surface unsuffixed, suffixal extensions may also be added to give applied, passive, habitual, direct causative, indirect causative, simultaneous, associative, possessive, reversive, reflexive, stative and nominalised forms. Of interest to us is the vowel raising induced within the verb root when certain of these suffixal extensions are added. In (3) we see the CVC verb forms of (2) along with their corresponding applied and indirect causative forms:

Other suffixal extensions that induce raising are the passive, direct causative, simultaneous, reversive and stative extensions. For example, these other suffixal extensions attach to /ten/, one of the verb roots in (3), to give [tina], [tinis], [tinha], [tinil] and [tiní], respectively.
Metrical constituency and rhythmic adjustment
Authors: Kager René , Visch Ellis
Published: October 2008

Over the past few years, research in metrical phonology has witnessed a shift in its main topic of investigation. Originally, attention was focused on the representation of prominence patterns of words (for example, Liberman & Prince 1977; Kiparsky 1979; Selkirk 1980; Hayes 1981), but more recently interest has arisen in several sorts of ‘rhythmic’ stress phenomena in larger domains (Prince 1983; Hayes 1984; Selkirk 1984; Hammond 1984; Giegerich 1985). One way of explaining this shift is by noting that the issue of the treatment of prominence patterns proper seems to have reached a stage where both grid-only (i.e. tree-less) theory and variants of tree-fulltheories, whether or not they employ grids as well, are capable of explaining the prominence patterns of words (see, for instance, Prince 1983; van der Hulst 1984). In this situation, investigation of rhythmic stress phenomena may offer the possibility of evaluating these theories because, as currently perceived, this area typically deals with the issue of whether metrical tree structure is needed at all, or whether grid structure by itself is capable of explaining rhythmic adjustments: on the one hand, grid-only theory claims that any constituency relevant to rhythmic adjustment is adequately encoded in the grid; on the other, tree theory holds that more detailed, or perhaps different, constituent information is required, as expressed in the metrical tree.
Aspects of underspecification theory
Authors: Archangeli Diana
Published: October 2008

An evaluation metric in Universal Grammar provides a means of selecting between possible grammars for a particular language. The evaluation metric as conceived in Chomsky & Halle (1968; henceforthSPE) prefers the grammar in which only the idiosyncratic properties are lexically listed and predictable properties are derived. The essence of underspecification theory is to supply such predictable distinctive features or feature specifications by rule. Viewed in this way, the general idea of underspecification has always been a part of any theory of phonology that includes such an evaluation metric.
Phonological implications of skeleton and feature underspecification in Kasem
Authors: de Haas Wim G.
Published: October 2008

The West African language Kasem, which is spoken by the Kasenas on both sides of the northern border between Ghana and Burkina Faso, figured prominently in the abstractness controversy in the late seventies. The analyses proposed by Halle (1978) and Phelps (1975, 1979), in particular, show most clearly that the framework of linear phonology does not provide a suitable model for the description of the complex set of alternations that can be observed in the nominal system of this language. I will argue that the theory of underspecification (cf. Kiparsky 1982, 1985; Archangeli 1984; among others) together with the principles of CV phonology (cf. McCarthy 1979, 1981; Clements & Keyser 1983; Levin 1985) provide the necessary equipment to account for the Kasem facts in a relatively simple and insightful way. It will turn out that these subtheories enable us to collapse several seemingly independent processes into a rather small set of language-specific rules.
Underspecification theory and Turkish rhyme
Authors: Malone Joseph L.
Published: October 2008

The mettle of approaches to synchronic linguistics can often be profitably tested by confrontation with language patterns from paralinguistic areas. In the following pages underspecification theory will be shown to play a central role in illuminating the nature of Turkish rhyme in the classical tradition, where the conditions for euphonic matching of vowels otherwise elude neat linguistic categorisation. As a by-product, the analysis also provides some clarification of a detail of suffix allomorphy.
Underspecification, the feature hierarchy and Tiv vowels
Authors: Pulleyblank Douglas
Published: October 2008

The major issue with regard to underspecification theory is whether all types of redundant information should be excluded from underlying representations, or if not, then what the principles are that determine the inclusion or exclusion of particular types of information. The vowel system of Tiv, a Niger-Congo language of Nigeria, is particularly interesting in this regard since the representation of individual vowels in verbal roots requires a type of radical underspecification: no features are actually assigned to vowels underlyingly; surface forms result from the interaction of morpheme-level specifications with rules of spreading and redundancy.
Underspecification in the height harmony system of Pasiego
Authors: Vago Robert M.
Published: October 2008

The recent phonological literature has witnessed the emergence of a significant body of research under the rubric of underspecification theory. This model of inquiry was first proposed by Kiparsky (1982), developed more deeply in Archangeli (1984), and is articulated most exhaustively in Archangeli & Pulleyblank (forthcoming a). One of the most basic assumptions advanced in these works is that for each contrastive feature one value is specified underlyingly and the other is inserted by default. Feature changing harmony, which requires both values to be underlying, is a particularly interesting challenge to this claim and appears to undermine its restrictiveness. Indeed, it figures prominently in some recent proposals, such as Steriade (1987b), to justify relaxing the theory and admit both feature values at the underlying level.
When is an Almost MonochromaticK4Guaranteed?
Authors: KOSTOCHKA ALEXANDR , MUBAYI DHRUV
Published: October 2008

Suppose thatn> (logk)ck, wherecis a fixed positive constant. We prove that, no matter how the edges ofKnare coloured withkcolours, there is a copy ofK4whose edges receive at most two colours. This improves the previous best bound ofkc′k, wherec′ is a fixed positive constant, which follows from results on classical Ramsey numbers.
A Weakening of the Odd Hadwiger's Conjecture
Authors: KAWARABAYASHI KEN-ICHI
Published: October 2008

Gerards and Seymour (see [10], p. 115) conjectured that if a graph has no odd complete minor of order l, then it is (l − 1)-colourable. This is an analogue of the well-known conjecture of Hadwiger, and in fact, this would immediately imply Hadwiger's conjecture. The current best-known bound for the chromatic number of graphs with no odd complete minor of order l is $O(l \sqrt{\log l})$ by the recent result by Geelen, Gerards, Reed, Seymour and Vetta [8], and by Kawarabayashi [12] later, independently. But it seems very hard to improve this bound since this would also improve the current best-known bound for the chromatic number of graphs with no complete minor of order l.

Motivated by this problem, in this note we show that there exists an absolute constant f(k) such that any graph G with no odd complete minor of order k admits a vertex partition V1, . . ., V496k such that each component in the subgraph induced on Vi (i ≥ 1) has at most f(k) vertices. When f(k) = 1, this is a colouring of G. Hence this is a relaxation of colouring in a sense, and this is the first result in this direction for the odd Hadwiger's conjecture.

Our proof is based on a recent decomposition theorem due to Geelen, Gerards, Reed, Seymour and Vetta [8], together with a connectivity result that forces a huge complete bipartite minor in large graphs by Böhme, Kawarabayashi, Maharry and Mohar [3].
Comparative slavery. A historian's view
Authors: Katsari Constantina
Published: October 2008

Jane Webster, in her article ‘Less beloved. Roman archaeology, slavery and the failure to compare’, brings into the limelight the necessity for archaeologists who study slavery to engage with the use of comparative methods. A brief historiographical analysis shows that, so far, only a handful of archaeologists are interested in performing a study of comparative slavery and probably even fewer are aware of the methodological complexities of such a task. Webster's article could not have been more timely. Historians are increasingly interested in studying connections and in making comparisons between people, sectors, countries and chronological periods. The emphasis on the study of comparative slavery in the UK is, for instance, demonstrated by the recent foundation of the Institute for the Study of Slavery (ISOS) at the University of Nottingham and its teaching in several other universities (Leicester, Newcastle, Edinburgh and King's College London among them). The development of comparative methodology, though, is still in its infancy. This may be one of the reasons why researchers are discouraged from undertaking such a task. Similarly, as Webster rightly notes, scholars tend to complain that the material is scanty and inadequate for the comparative reconstruction of past civilizations. Prominent among these is Walter Scheidel, who altogether, despite his comparative studies on slavery, remains unconvinced about the usefulness of comparisons in archaeology (Scheidel 2003, 581).
Signs of identity, signs of memory
Authors: Cipolla Craig N.
Published: October 2008

This essay explores everyday practices as sites of memory-making, arguing that such practices have the potential to serve as markers and makers of cultural identity. I use frameworks of social memory to interpret 19th-century butchery practices on the Eastern Pequot reservation in North Stonington, Connecticut. Colonialism meant change for Pequot peoples, including shifts in family structures and the adoption of mass produced material culture. I argue that, within these abrupt changes, social memory and memory-making practices played a central role in maintaining and congealing indigenous identity. I examine evidence of changing butchery practices on the reservation as they related to the adoption of metal tools. Archaeological investigations demonstrate that even though the Eastern Pequot increasingly used metal tools for butchery, they also continued to use chipped tools made of either stone or glass. I suggest that this pattern is significant because of the ‘mnemonic’ qualities that chipped-tool usage might have carried on reservation grounds. These mnemonic practices served as binding ties for the reservation community.
Excess heterozygosity and scarce genetic differentiation in the populations of Phoenix dactylifera L.: human impact or ecological determinants
Authors: Elshibli Sakina , Korpelainen Helena
Published: October 2008

Extensive research has been conducted on the characterization of hundreds of date palm (Phoenix dactyliferaL.) cultivars worldwide. However, the population genetics of date palms has never been studied. In this study, we collected 200 individuals from 19 populations of different geographical locations in Sudan. The collection sites were grouped according to the type of dates (date palm fruits) that dominates in the area. Ten microsatellite markers were used to investigate the genetic diversity within and among populations and the correlation between the genetic and geographical distances. The tested microsatellite markers showed a high level of polymorphism. A total of 261 alleles were detected at the ten loci. The overall mean value of fixation indices equalled − 0.163, which shows the presence of excess heterozygosity. However, the χ2tests conducted for every locus in each population indicated no significant deviation from the Hardy–Weinberg equilibrium. The analyses of molecular variance exhibited that about 95% of the total genetic variation existed within populations, while significant differentiation within the type groups could be detected. Although significant isolation by distance (r2 = 0.552,P < 0.05) was detected by a Mantel test, it seems that the spatial effect has become complicated as a result from the exchange and introduction of different kinds of plant materials by date palm growers and traders, as well as seed dispersal. This complexity was clearly apparent in the weak clustering relationships among most of the tested populations.
Polar stratospheric clouds at the South Pole from 5 years of continuous lidar data: Macrophysical, optical, and thermodynamic properties
Authors: Campbell James R. , Sassen Kenneth
Published: October 2008

An eye‐safe micropulse lidar (MPL; 0.523 μm) has operated at the Scott‐Amundsen South Pole Station, Antarctica, since December 1999 to collect continuous long‐term measurements of polar clouds. A 5‐year data subset is presented here to describe macrophysical, optical, and thermodynamic properties of polar stratospheric clouds (PSC) in austral winters 2000 and 2003–2006. PSC cloud occurrence is examined relative to seasonal temperature and theoretical chemical structure. A linear relationship is established with high correlation between total integrated PSC scattering and ozone loss for 2000 and 2003–2005 when springtime overturning of the air mass occurred nominally. In 2006, ozone‐depleted air persisted over the South Pole through the end of December. In this case, overturning of the air mass was limited temporally by vortex‐related mechanisms, and any correlation with PSC occurrence was eliminated. PSC formed near and above 18.0 km above mean sea level (MSL) in late May and early June likely influence clouds formed at lower heights later in the season from sedimentation, evaporation/sublimation, and repartitioning of nitrogen and water vapor in the air mass bounded by the dynamic polar vortex. Conceptual profiles for seasonal PSC occurrence and thermal structure are described. PSC are common to near and above 20.0 km MSL through June. After this, they are most frequent near 15.0 km MSL through August.
Assessing internal and external controls on lake water quality: Limitations on organic carbon‐driven alkalinity generation in acidic pit lakes
Authors: Salmon S. U. , Oldham C. E. , Ivey G. N.
Published: October 2008

Organic carbon‐driven alkalinity generation in acidic pit lakes may lead to amelioration of lake pH. However, characterization of a pit lake (pH 4–5) with respect to temporal and spatial variation in state variables in the water column and inflows indicated that while the lake was a net sink for organic carbon, this carbon was either not being converted to alkalinity on a significant scale, or there were additional sources of acidity, possibly in the form of iron‐rich groundwater. Internal organic carbon generation is limited by the availability of phosphorus; this limitation, together with internal carbon sinks, may be enhanced by the acidic conditions in the lake. This study has highlighted that well‐constrained external mass balances, as well as assessment of integrated effects of internal geochemical, physical, and biological processes, are critical for forward prediction of water quality in pit lakes.
Leaching surfaces to characterize transport in a heterogeneous aquifer: Comparison between flux concentrations, resident concentrations, and flux concentrations estimated from temporal moment analysis
Authors: Bloem E. , Vanderborght J. , de Rooij G. H.
Published: October 2008

For subsurface solute transport, flux concentrations are key, while usually resident concentrations are measured. Flux concentrations are frequently estimated from resident concentrations by temporal moment analysis. We tested this approach by simulating transport of an injected tracer during steady flow in an aquifer with a heterogeneous saturated hydraulic conductivity. We constructed grid cell–scale breakthrough curves (BTCs) from flux concentrations and approximated BTCs from resident concentrations and estimated flux concentrations. We assembled these BTCs into spatiotemporal leaching surfaces at various aquifer cross sections for subsequent analysis. Resident concentrations were unsuitable to assess solute movement in the aquifer. Temporal moment analysis worked well when the entire aquifer cross section was considered but performed poorer at the grid cell scale because it approximates the local velocity by the trajectory average. The leaching surfaces served as valuable tools to demonstrate and quantify the limitations of temporal moment analysis.
A seismic stratigraphic analysis of Mariana forearc basin evolution
Authors: Chapp Emily , Taylor Brian , Oakley Adrienne , Moore Gregory F.
Published: October 2008

New seismic data collected in the 14.5°–18.5°N Mariana segment of the Izu‐Bonin‐Mariana island arc system image six seismic stratigraphic sequences that can be mapped throughout the inner forearc. These sediments were most likely deposited from 35 Ma to the present. The oldest stratigraphic Units 1, 2, and 3 are syn‐rift volcaniclastic deposits. Unit 4 deposits accumulated during a period of mild structural inversion, which resulted in several isolated reverse‐faulted anticlines within the forearc sedimentary basin. A late period of extensional deformation began near the end of Unit 5 deposition and continued through Unit 6 sedimentation to the present. Seismic lines show that the basement of the forearc is composed of large rotated fault blocks and half grabens with NE, NW, and NNE trends. Fault offset calculations show that basement faults with dips between 45° and 50° account for only ∼4% total extension in the forearc. South of 16.3°N, normal growth faults initiated during basement extension offset the frontal arc high from a deep forearc basin. From correlations with the known geologic history, we hypothesize that extension during deposition of Units 1 through 3 corresponds to rifting of the Eo‐Oligocene Arc, between ∼35 Ma and 29 Ma, older deposits being too thin to be seismically resolvable. Localized compression during Unit 4 accumulation occurred some time after Eo‐Oligocene rifting in the early Miocene. Late‐stage normal faulting near the end of deposition of Unit 5 and throughout Unit 6 accumulation may be associated with the opening of the Mariana Trough backarc basin from ∼8 Ma years to the present. There is a higher density of these later faults in the inner forearc between 15.5° and 17°N and in the outer forearc between 14°N and 18°N. Recent extension is at least partially accommodated by reactivation of older basement faults with the same NE, NW, and NNE‐ trends. Stratigraphic relationships indicate that the inner forearc south of 16.3°N has differentially subsided and tilted trenchward, possibly as a result of a recent change in subducting slab geometry or subducted relief under the forearc.
Thermal structure of the crust in the Gibraltar Arc: Influence on active tectonics in the western Mediterranean
Authors: Soto Juan I. , Fernández‐Ibáñez Fermín , Fernàndez Manel , García‐Casco Antonio
Published: October 2008

We have modeled thermal structure of the crust in the western Mediterranean on the basis of inversion of heat flow and elevation in the context of Airy's isostatic equilibrium. Modeling results reveal dramatic variations in crustal temperatures within the Gibraltar Arc region. The steep gradients in crustal thickness, together with the regional heat flow pattern lie at the origin of temperature anomalies. Temperatures at the base of the crust range between <500°C in the West Alboran Basin, where sediment accumulations exceed 8 km, and >700°C in the eastern Betics and the connection between the Rif and Tell belts in North Africa, where a high heat flow anomaly occurs. High‐temperature zones define a hotter region (>650°C) running SW–NE across the central part of the Alboran Sea. These results agree with other geophysical evidence (e.g., low deep‐crust Vp and Pn values) suggesting the occurrence of high temperatures in the deepest crust. According to the estimated silicic composition of the deep crust in the area, temperatures in some regions are appropriate for partial melting under muscovite dehydration conditions (>700°C). We have estimated that average partial melting ranges from ∼12% (maximum XL) in the western Tell region to ∼6% in the eastern Betics. This process modifies physical and mechanical properties of the deep crust enhancing crust‐mantle decoupling and deep crustal flow with concomitant surface uplift. These mechanisms explain why high topography and active E–W extension occur transecting the overall orogenic trend of the Gibraltar Arc.
Morin transition in hematite: Size dependence and thermal hysteresis
Authors: Özdemir Özden , Dunlop David J. , Berquó Thelma S.
Published: October 2008

Hematite is a frequently used mineral in paleomagnetic and environmental magnetic studies. Just below room temperature, it undergoes a magnetic phase transition, the Morin transition, whose nature is an important part of our basic understanding of hematite's magnetism and magnetic memory. We have determined the temperature TM of the Morin transition from saturation remanence warming curves to be 250–261 K for 0.5–6 mm hematite natural single crystals, 257–260 K for 45–600 μm sieved crystal fractions, and 241–256 K for submicron synthetic hematites with grain sizes between 120 and 520 nm. The variation must be due to differences in crystal morphology, lattice strain, and crystal defects common in both synthetic and natural crystals. Our results are compatible with published data for 100 nm to 10 mm hematites and show that TM is nearly size independent, decreasing very gradually as particle size decreases over this broad range, which includes both multidomain (MD) and single‐domain (SD) structures. However, TM decreases sharply between 90 and 30 nm. Below 20 nm, the transition disappears entirely as near‐surface spins deviate strongly from the antiferromagnetic easy axis. Our SD and MD hematites exhibit a thermal hysteresis in the Morin transition: the values of TM in cooling and in heating are different. For the same cooling/warming rate, ΔTM is much greater for submicron hematites than for larger crystals. We attribute the lag in the transition in both cooling and heating to crystal imperfections and resulting internal stresses, and speculate that defects may serve to pin and stabilize surface spins. Preventing spin rotation in a region large enough to trigger the phase transition would inhibit destabilization of the weakly ferromagnetic phase in cooling and the antiferromagnetic phase in heating. The wide distribution of particle sizes in our submicron samples may also play a role.
Thirty‐year gravity change at Mount Baker Volcano, Washington, USA: Extracting the signal from under the ice
Authors: Crider Juliet G. , Hill Johnsen Kristin , Williams‐Jones Glyn
Published: October 2008

Mount Baker in the Cascade Volcanic Arc displayed an unexplained period of increased fumarolic activity in 1975 and has since been quiescently degassing. We reoccupied gravity stations near the active crater and on the south flank of the volcano, initially measured in 1975–1981. We observe 1800 ± 300 μGal gravity increase at the crater since 1977. Estimates of snow and ice volume change suggest these environmental factors significantly mask gravity change due to magmatic and hydrothermal sources; correcting for environmental factors could double the observed gravity increase. Hydrothermal recharge, magma intrusion, and significant deflation are rejected as explanations for the source of the gravity change. Densification of a magma body emplaced in 1975 is consistent with our gravity observations and with deformation and degassing data. Shallow pyrite precipitation may also contribute to the gravity increase.
Atmospheric correction of SeaWiFS ocean color imagery in the presence of absorbing aerosols off the Indian coast using a neuro‐variational method
Authors: Brajard J. , Moulin C. , Thiria S.
Published: October 2008

This paper presents a comparison of the atmospheric correction accuracy between the standard sea‐viewing wide field‐of‐view sensor (SeaWiFS) algorithm and the NeuroVaria algorithm for the ocean off the Indian coast in March 1999. NeuroVaria is a general method developed to retrieve aerosol optical properties and water‐leaving reflectances for all types of aerosols, including absorbing ones. It has been applied to SeaWiFS images of March 1999, during an episode of transport of absorbing aerosols coming from pollutant sources in India. Water‐leaving reflectances and aerosol optical thickness estimated by the two methods were extracted along a transect across the aerosol plume for three days. The comparison showed that NeuroVaria allows the retrieval of oceanic properties in the presence of absorbing aerosols with a better spatial and temporal stability than the standard SeaWiFS algorithm. NeuroVaria was then applied to the available SeaWiFS images over a two‐week period. NeuroVaria algorithm retrieves ocean products for a larger number of pixels than the standard one and eliminates most of the discontinuities and artifacts associated with the standard algorithm in presence of absorbing aerosols.
About the increase of HNO3 in the stratopause region during the Halloween 2003 solar proton event
Authors: Verronen P. T. , Funke B. , López‐Puertas M. , Stiller G. P. , von Clarmann T. , Glatthor N. , Enell C.‐F. , Turunen E. , Tamminen J.
Published: October 2008

In this paper, we explain the HNO3 observations made with the MIPAS/Envisat instrument in the northern polar region at the time of the October‐November 2003 solar proton event. Increases of 0.5–5.5 ppbv are seen at altitudes 35–58 km after the onset of the event. Results from the Sodankylä Ion and Neutral Chemistry model are in good agreement with the MIPAS observations, except at around 58 km where the modeled mixing ratios are about a factor of two larger. According to the model results, HNO3 production at altitudes above 35 km is almost entirely due to ion‐ion recombination between NO3− and H+ cluster ions. At 35 km and below, there is contribution also from N2O5 reacting with ions as well as from NO2 reacting with OH.
Observations of molecular oxygen ions in Saturn's inner magnetosphere
Authors: Martens Hilary R. , Reisenfeld Daniel B. , Williams John D. , Johnson Robert E. , Smith H. Todd
Published: October 2008

We present an analysis of molecular oxygen ion (O2+) abundance in Saturn's inner magnetosphere based on observations made with the Cassini Plasma Spectrometer (CAPS). Using data summed over 23 orbits, we resolve and isolate O2+ counts from the tail of the water group ion mass distribution (W+ [O+, OH+, H2O+, H3O+]) and from background sources. O2+ was initially estimated at ∼1–2% of the total ion population in the inner magnetosphere based on CAPS data from the Saturn orbital insertion pass. Through refined analysis techniques, we have found O2+ to account for just above 0.3% of all W+ ions at L = 4.5, with only minor fluctuations in relative density out to L = 7.5 − 8.0. Beyond L = 7.5, the relative O2+/W+ abundance exhibits a statistically significant increase through L = 10.5, which may indicate a neutral O2 source in the vicinity of Rhea.
Cluster observations of fast shocks in the magnetosheath launched as a tangential discontinuity with a pressure increase crossed the bow shock
Authors: Maynard N. C. , Farrugia C. J. , Ober D. M. , Burke W. J. , Dunlop M. , Mozer F. S. , Rème H. , Décréau P. , Siebert K. D.
Published: October 2008

The interaction of a tangential discontinuity (TD) and accompanying dynamic pressure increase with the Earth's bow shock launches a fast shock that travels ahead of the TD in the magnetosheath and carries a significant portion of the pressure change. In this event study, we use observations from the Cluster spacecraft and magnetohydrodynamic simulations to identify the fast shock and its properties and to track the TD in the magnetosheath. Velocities of the fast shock and the TD were determined by triangulation using the four distant Cluster spacecraft. The fast shock is a planar structure, traveling nearly perpendicular to B at the magnetosonic speed in the plasma rest frame. Changes in density and ∣B∣ are correlated, with about a 20% increase in each. A current was observed tangential to the plane of the fast shock, and the positive E •J there provided an electromagnetic energy source for the observed heating of the ions. The fast shock is generated by the pressure change and determines the timing of the initial response of the magnetopause to that change. The TD was moving nearly in the −XGSE direction and was being compressed as it moved inward. The passage of the TD ushered in large‐scale compressive structure in the magnetosheath magnetic field, which satisfied the mirror mode instability criterion. Velocities of a fast rarefaction wave, reflected from the magnetopause, and an additional slow‐mode structure, which was not a product of the initial interaction with the bow shock, were determined by triangulation.
Radiation belt electron precipitation by man‐made VLF transmissions
Authors: Gamble Rory J. , Rodger Craig J. , Clilverd Mark A. , Sauvaud Jean‐André , Thomson Neil R. , Stewart S. L. , McCormick Robert J. , Parrot Michel , Berthelier Jean‐Jacques
Published: October 2008

Enhancements of drift‐loss cone fluxes in the inner radiation belt have been observed to coincide with the geographic location of the powerful VLF transmitter NWC. In this paper we expand upon the earlier study to examine the occurrence frequency of drift‐loss cone enhancements observed above transmitters and the intensity of the flux enhancements and to demonstrate the linkage to transmitter operation. Our study has confirmed the strong dependence that these enhancements have upon nighttime ionospheric conditions. No enhancements were observed during daytime periods, consistent with the increased ionospheric absorption. We have also confirmed the persistent occurrence of the wisp features east of the NWC transmitter. The enhancements are initially observed within a few degrees west of NWC and are present in 95% of the nighttime orbital data east of the transmitter for time periods when the transmitter is broadcasting. No enhancements are observed when NWC is not broadcasting. This provides conclusive evidence of the linkage between these drift‐loss cone electron flux enhancements and transmissions from NWC. When contrasted with periods when NWC is nonoperational, there are typically ∼430 times more 100–260 keV resonant electrons present in the drift‐loss cone across L = 1.67–1.9 owing to NWC transmissions. There are almost no wisp‐like enhancements produced by the transmitter NPM, despite its low‐latitude location and relatively high output power. The lack of any wisp enhancement for L < 1.6 suggests that nonducted propagation is an inefficient mechanism for scattering electrons, which explains the lower cutoff in L of the NWC‐generated wisps and the lack of NPM‐generated wisps.
Cation disorder in ringwoodite and its effects on wave speeds in the Earth's transition zone
Authors: Panero Wendy R.
Published: October 2008

Inclusion of the effects of point defects on ringwoodite's elasticity helps reconcile mineralogical models of the transition zone with seismic observations of the impedance contrast at 520‐km depth. This study uses density functional theory to calculate the disorder and its effects on the elasticity of Mg2SiO4‐spinel (ringwoodite) in the Earth's transition zone. Spinel‐structured Mg2SiO4, ringwoodite, also can contain significant amounts of thermally activated coupled point defects between Mg sites and Si sites. The energetics of Mg2SiO4‐spinel, inverse spinel, and disordered structures show ∼4% Mg‐Si disorder in the mantle's transition zone, where 100‐K lateral temperature variations can cause approximately 1.2% change in disorder. Lateral temperature variations in the transition zone lead to wave speed changes because of the minerals' intrinsic temperature‐related elasticity changes. Independent of temperature, 1% cation disorder causes an additional decrease in c11 and c44 of 0.8% and 0.4%, respectively. Since the structure and stability of the Mg2SiO4 polymorphs play a key role in the density and impedance contrasts across the boundaries in the Earth's transition zone, the effect of defects has to be taken into account.
Exchange fluxes of Hg between surfaces and atmosphere in the eastern flank of Mount Gongga, Sichuan province, southwestern China
Authors: Fu Xuewu , Feng Xinbin , Wang Shaofeng
Published: October 2008

In situ total gaseous mercury (TGM) concentrations and mercury exchange fluxes from 17 sampling sites of three representative landscapes (agriculture, grassland, and forest) were intensively measured in the eastern flank of Mount Gongga area, Sichuan province, southwestern China, from October 2005 to September 2006. Average TGM concentrations in ambient air ranged from 1.60 to 5.10 ng m−3 in warm season, while the values were highly elevated in cold season with the highest mean TGM concentration of 7.65 ng m−3. Hg fluxes from agriculture and grassland sampling sites showed clearly seasonal distribution pattern with net depositions observed in cold season and net emissions observed in warm season. Mean Hg fluxes at agriculture and grassland field fell in the range from −4.1 to 132.0 ng m−2 h−1 and from −18.7 to 13.4 ng m−2 h−1, respectively, while mean Hg fluxes from forest sites varied from 0.5 to 9.3 ng m−2 h−1. Notable diurnal pattern of Hg fluxes were observed from all sampling sites, with the maximum Hg fluxes observed at midday and the minimum values observed during the nighttime. TGM concentrations in cold season significantly negatively correlated with Hg flux, suggesting that highly elevated TGM concentration could inhibit Hg emission even cause significant deposition. Vegetation acted as a great sink of air Hg in cold season, while in warm season, it could significantly inhibit Hg emission from surfaces.
Relationship between ice water content and equivalent radar reflectivity for clouds consisting of nonspherical ice particles
Authors: Hong Gang , Yang Ping , Baum Bryan A. , Heymsfield Andrew J.
Published: October 2008

This study investigates the relationship between ice water content (IWC) and equivalent radar reflectivity (Ze) at 94 GHz for clouds consisting of nonspherical ice particles with geometrical shapes of hexagonal solid and hollow columns, plates, 6‐branch bullet rosettes, aggregates, and droxtals. The IWC is calculated from a set of 1119 ice particle size distributions (PSDs) measured during several field campaigns, which are discretized to 46 size bins based on particle maximum dimensions ranging from 2 to 10500 μm. The Ze at 94 GHz is calculated from the radar backscattering properties obtained by integrating over the PSD and chosen particle habit distributions. The influence of ice habit on the Ze‐IWC relationship is investigated for ice clouds composed of individual ice particle habits and a habit mixture. The Ze‐IWC relationship is found to be sensitive to cloud effective particle size and cloud temperature. For an ice cloud with a given IWC, the Ze tends to increase with increasing effective particle size. Similarly, the Ze generally increases with increasing cloud temperature, at least for clouds with IWC over 0.01 g/m3. These features are consistent with the observed relationship between effective particle sizes and cloud temperatures. The present investigation of the effect of temperature on the Ze‐IWC relationship indicates that including temperature in the Ze‐IWC relationship may not improve the estimates of IWC. However, the dependence of the Ze‐IWC relationship on the effective particle size within a given temperature range is more pronounced, and may be potentially useful for inferring the cloud effective particle size from the Ze‐IWC relationship.