bluuebunny/crossref_metadata_2025 huggingface dataset:
On Embedding Synfire Chains in a Balanced Network
Authors: Aviel Y. , Mehring C. , Abeles M. , Horn D.
Published: May 2003

We investigate the formation of synfire waves in a balanced network of integrate-and-fire neurons. The synaptic connectivity of this network embodies synfire chains within a sparse random connectivity. This network can exhibit global oscillations but can also operate in an asynchronous activity mode. We analyze the correlations of two neurons in a pool as convenient indicators for the state of the network. We find, using different models, that these indicators depend on a scaling variable.

Beyond a critical point, strong correlations and large network oscillations are obtained. We looked for the conditions under which a synfire wave could be propagated on top of an otherwise asynchronous state of the network. This condition was found to be highly restrictive, requiring a large number of neurons for its implementation in our network. The results are based on analytic derivations and simulations.
Laplacian Eigenmaps for Dimensionality Reduction and Data Representation
Authors: Belkin Mikhail , Niyogi Partha
Published: May 2003

One of the central problems in machine learning and pattern recognition is to develop appropriate representations for complex data. We consider the problem of constructing a representation for data lying on a low-dimensional manifold embedded in a high-dimensional space. Drawing on the correspondence between the graph Laplacian, the Laplace Beltrami operator on the manifold, and the connections to the heat equation, we propose a geometrically motivated algorithm for representing the high-dimensional data. The algorithm provides a computationally efficient approach to nonlinear dimensionality reduction that has locality-preserving properties and a natural connection to clustering. Some potential applications and illustrative examples are discussed.
The influence of familiarity, age, experience and female mate choice on pregnancies in captive grey mouse lemurs
Authors: Radespiel Ute , Zimmermann Elke
Published: May 2003

Conceptions in mammals may depend on a variety of factors including mate familiarity, age, sociosexual experience and female mate choice. We tested predictions for the effects of these factors on pregnancies in a captive colony of grey mouse lemurs (Microcebus murinus). The succession of oestrous cycles and pregnancies was analysed for a total of 26 different females that were housed together with 33 different males over a total of 124 oestrous cycles between 1995 and 2001. In addition, sexual behaviours were recorded and analysed over 13 oestrous cycles of 9 different females. An effect of mate familiarity on pregnancies could be detected by a frequent delay of pregnancies to the second cycle of the season (66.7% of the possible cases). Female age influenced pregnancies as the 2-3-year old females were less likely to become pregnant than females of other age classes. This reduced rate of pregnancies, however, was probably due to the lack of previous sociosexual experience with males. Females that have not been housed with males within their first reproductive season, needed one or two years of sociosexual experience before their first successful impregnation. These findings are discussed as a side effect of the ontogenetic development of female dominance. Female mate choice could be deduced from the succession of pregnancies and the strong responsibility of the females for the termination of matings.
The trade-off between singing and mass gain in a daytime-singing bird, the European robin
Authors: Thomas Robert , Goldsmith Arthur , Cuthill Innes , Lidgate Helena , Burdett Proctor Selene , Cosgrove Delia
Published: May 2003

The functions of bird song are well described, but empirical studies examining the costs of singing are scarce. Two potential costs are a metabolic cost of singing, and lost feeding opportunities, but such energetic costs will only be biologically important if they have a significant effect on the bird's body reserves. Overnight loss of reserves has previously been found to increase with increasing song rates in nocturnally singing common nightingales Luscinia megarhynchos. However, it is not clear how such costs compare with those incurred by daytime-singing birds, which may forfeit foraging opportunities when they sing. In this paper we investigated the effect of variation in song rate on the body reserves of a typical daytimesinging bird, the European robin Erithacus rubecula, singing at different rates in three different circumstances: (i) Natural variation in song rate of free-living robins. (ii) Manipulations of the song rate of free-living robins using playbacks of conspecific song. (iii) Manipulations of the song rate of aviary-housed robins using playbacks of conspecific song. In all three parts of our study, birds gained less mass when they sang more. Our analyses suggested that this might have been due primarily to a reduction in food intake rate, rather than to the metabolic cost of the singing itself or a concurrent increase in locomotor costs. These results together demonstrate that the costs of singing, as measured by their overall net effects on body reserves, can have a significant impact on the energetic state of daytime-singing birds.
Male consortship behaviour in chacma baboons: the role of demographic factors and female conceptive probabilities
Authors: Henzi S. Peter , Hill Russell , Barrett Louise , Lycett John , Weingrill Tony
Published: May 2003

There is evidence for a general relationship between male dominance rank and mating success in primates, although the strength of this relationship differs among species. In chacma baboons (Papio hamadryas ursinus) male rank is found to be of more importance than in the other savannah baboon subspecies. However, even though the priority-of-access model explains the proportion of time spent in consortship for males of different rank in chacmas, highest-ranking males usually consort less often than expected. In this study, conducted in the Drakensberg Mountains of Natal and at De Hoop in the Western Cape, we investigated why dominant males in four study troops consorted only between 50% and 75% of days that they were expected to consort according to the priority-of-access model. Consortship success of highest-ranking males was primarily dependant on the number of available oestrous females in a troop. This was likely due to costs involved in consorting which limit the amount of days that a male could spend in consortship. Females pass through several cycles before conceiving and highest-ranking males were observed to consort more often on the conceptive cycle compared to the nearest nonconceptive cycle, but this was only true for males that were already resident for several months. Recently immigrated males that became highest-ranking often consorted during nonconceptive female cycles, while older, lower-ranking males consorted during the conceptive cycles. We propose that males with longer residency have more information about reproductive state of females and thus higher reproductive success than recently immigrated males.
Deconstructing the Peasantry: Class and Development in Rural Kenya
Authors: Githinji Mwangi Wa , Cullenberg Stephen E.
Published: May 2003

This essay illustrates the power and reach of the new Marxian class analysis when it is applied to the economic development of the third world. Economic development in third world countries has been analyzed, debated, and promoted but the implications of class analysis (in the surplus labor sense) have rarely been explored. This essay will reexamine the concept of the peasantry that has played such an important theoretical role in Marxist theories of development. In contrast to the typical concept of the peasantry as a rather homogeneous group differentiated according to levels of income and/or property ownership, we develop a theory of the peasantry based on a surplus labor theory of class. A surplus labor theory of class will allow us to investigate in a systematic way how the multiple class structures of so-called less developed rural economies contributed to their “underdevelopment.” This question derives in part from Kautsky's parallel inquiry into the nature of the class structure in the rural economy of a country supposedly in transition from pre-capitalist to capitalist forms of production. We redirect this question to investigate empirically the complex class nature of rural Kenya by looking at data concerning household productive activities. Based on our findings we will explore the implications for political action and policy that promote various forms of non-exploitative class structures in rural Kenya.
KHARJAS AND VILLANCICOS
Authors: Armistead Samuel
Published: May 2003

Scholarship surrounding the kharjas, concluding qufls in the Hispano-Romance Mozarabic dialect, appended to muwashshahāt written in Arabic or Hebrew by 11th- to 14th-century Muslim and Jewish authors in al-Andalus, has been characterized by bitterly acrimonious polemics, sometimes involving even personal ad hominem criticism. While the kharjas are indubitably an integral part of the Hispano-Semitic poems in which they have survived, and can and should be legitimately studied within that context, some recent attempts have been put forward to deny that there is any relationship between the Romance kharjas and other manifestations of primitive lyric poetry in Castilian and Galician-Portuguese that are well documented in Medieval Iberia. The present article reviews the available evidence, which undeniably points to an intimate relationship between the Mozarabic verses and Castilian villancicos ("peasant songs") and Old Portuguese cantigas de amigo ("songs about lovers"). Consistent and abundant parallels between the three forms are discussed and exemplified in terms of themes, motifs, metrics, formulaic diction, and traditional "intuitive" style. The kharjas turn out to be crucially important as the earliest known documents of the oral-traditional Romance lyric poetry sung in Medieval Iberia and throughout the Mediterranean world during the Middle Ages and even before. The kharjas are, then, best viewed as essentially amphibious poems that should be productively and collaboratively studied by Arabists, Hebraists, and Hispanists.
THE DĪWĀN OF AL-SHARĪF AL-TALĪQ
Authors: Neale Harry
Published: May 2003

This article presents the reconstructed dīwān of the Andalusī poet Marwān b. Abd al-Rahmān b. Marwān b. Abd al-Rahmān al-Nāsir al-Sharīf al-Talīq (d. 400/1009). This reconstruction has been assembled from fragments of poetry attributed to al-Sharīf al-Talīq that are found in various compilations of biographies of Andalusī poets. The late Spanish scholar, Emilio García Gómez, included translations of a number of these fragments in his study of Andalusī poetry, Cinco poetas musulmanes: biografías y estudios (Madrid: Espana-Calpe, 1944). In addition to presenting the existing fragments of the dīwān, including fragments that García Gómez did not have at his disposal, I undertook a thematic reading of the dīwān with attention to the imagery and motifs that recur within the poems. In this way, I hope to distill a specific voice that is the lyric idiom of this little-studied poet. The frame of reference for the analysis of the dīwān is a fragmentary qāfiyyah by al-Sharīf al-Talīq. This qasīdah has been selected because it offers the most complete repertoire of the imagery and vocabulary of al-Sharīf al-Talīq's poetry available to us.
DOING THINGS WITH ODES: A POET'S PLEDGES OF ALLEGIANCE: IBN DARRĀJ AL-QASTALLĪ'S HĀ'IYYAH TO AL-MANSŪR AND RĀIYYAH TO AL-MUNDHIR
Authors: Al-Mallah Majd Yaser
Published: May 2003

This article analyzes two of Ibn Darrāj al-Qastallī's famous odes presented to al-Mansūr b. Abī 'Āmir (d. 392/1002) and Mundhir b. Yahyā (d. 412/1022). Applying speech act theory reveals that these odes perform the illocutionary act, to use speech act terminology, of obligating the patron to reward the poet as a symbol of establishing a mutual relationship that is based on the poet's pledge of allegiance and the patron's acknowledgment of obligation toward the poet. The analysis focuses on what the panegyric ode does and what effect it has on the poet and patron within a proper context in the community. The paper uses speech act theory as a general framework for the ritual of gift exchange, which consists of giving (the poem as a gift), receiving (the poem by the patron), and repaying (the poet). This ritual establishes specific obligations between poet and patron that allow the panegyric ode to accomplish specific objectives. The paper also compares the function of each of the two odes in the context of the different political circumstances under which they were presented and shows how these circumstances affect the structure of each ode.
THE NŪNIYYA OF IBN ZAYDŪN: A STRUCTURAL AND THEMATIC ANALYSIS
Authors: Farrin Raymond
Published: May 2003

In this article I discuss the structural and thematic unity in Ibn Zaydūn's Nūniyya, perhaps the most famous poem from the period of Arab civilization in al-Andalus. I show that the ghazal is organized according to the principles of ring composition and that it is further characterized by a logical transition from formal to intimate address for the beloved and a thematic opposition between morning and night. The Nūniyya comprises five discrete sections: A - B - C - B1 - A1. Section A introduces the idea of the poet's separation from his beloved, Wallāda, and culminates in a mood of hopelessness and resignation. Morning is associated with this somber reality. In section B, Ibn Zaydūn addresses Wallāda formally and recalls that their nights together were blissful. Section C constitutes the heart of the poem, a paean to Wallāda's beauty and royal stature. At the end of C, the poet switches to an intimate form of address, having implied that, her nobility notwithstanding, he is an equal by the agency of sensual love. B1 and A1 correspond thematically to sections B and A, yet the tone becomes increasingly personal at the end of the poem, consonant with private subject matter and an appeal for a reply. The ghazal concludes at the point when figurative night, filled with its dreams of Wallāda and hopes for a response, is about to be replaced by the bleak morning hour and hopelessness of the introduction, suggesting an awareness on behalf of the poet that word from the beloved will not likely come.
AL-SHANFARĀ AND "THE MOUNTAIN POEM" OF IBN KHAFĀJA: SOME OBSERVATIONS ON PATTERNS OF INTERTEXTUALITY
Authors: Liebhaber Sam
Published: May 2003

The debt owed by the Andalusī poet Ibn Khafāja (d. 533/1138) to the sa'ālīk for the development of his symbolic/poetic idiom has been examined closely by Nadia Yaqub in her article, "Some of Us Must Depart: An Intertextual Reading of the Mountain Poem by Ibn Khafāja" (Journal of Arabic Literature 30, 1999). This article carries the association even further, arguing that much of the lexical and thematic stock of the Bā'iyya ("The Mountain Poem") of Ibn Khafāja is directly transplanted from the Lāmiyya of al-Shanfarā. A comparative reading of the two qasīdas , with close attention paid to the shared motifs and topoi, illustrates a key mechanism in Ibn Khafāja's adaptation of the early Arabic thematic repertoire to his own poetics. This technique can be described as the mechanism of "folding," whereby the discrete topoi and motifs of early Arabic verse are collapsed into single figures with polyvalent significance. This technique is illustrated in Ibn Khafāja's redeployment of the traditional lyric topoi of wolves, the lightning watch, and mountains. The thematic conflation embodied by the final motif of the Bā'iyya, the mountain, offers a comment on the state of Andalusī poetics at the time of Ibn Khafāja, to wit, the fatigue of convention with its densely layered symbolic burdens.
POETIC PILGRIMAGES: FROM BAGHDAD TO ANDALUCÍA, ABŪ TAMMĀM'S LĀ ANTA ANTA WA-LĀ AL-DIYĀRU DIYĀRU
Authors: Vázquez Miguel Ángel
Published: May 2003

Many García Lorca scholars have focused on the surrealist imagery in his "Romance sonámbulo" ("Sleepwalking Ballad"), one of his finest poems. This article focuses on the classical Arabic poetic resonance in the following verse: "Yo ya no soy yo, ni mi casa es ya mi casa" ("I am no longer I, my house no longer my house"). The verse echoes the opening line of Abū Tammām's (9th century) panegyric qasīdah to Abū Sa'īd al-Thaghrī: "You are not you, the abodes are not the abodes." The verse in turn was later quoted by Ibn Khafāja (12th century) in his elegiac ode to the fall of Valencia when the Çid conquered it. By calling upon the Arabic tradition behind this verse, the author wishes to shed some light on the poetical force that allows García Lorca's rendering to be effective in much the same way as the verse was in its Arabic original context. The verse in question may be seen as the culmination of a very old Arabic literary topos known as the atlāl-nasīb. The ruins of the abandoned encampment (the abodes of the poet's beloved) become a leitmotif of the awareness of lost happiness. Such a profound realization provides the elegiac mood that characterizes the nasīb or love prelude that opens the typical tripartite qasīdah. The ruined abode (or the abandoned encampment) allows the poet to establish a mnemonic and metonymic relationship with its former inhabitants, thus stirring the poet's memory. The physical place, then, becomes a poetic locus. What is noteworthy in Lorca's appropriation is the fact that he understood the meaning of Abū Tammām's verse at the archetypal level.
THE DECLINE OF COURTLY PATRONAGE AND THE APPEARANCE OF NEW GENRES IN ARABIC LITERATURE: THE CASE OF THE ZAJAL, THE MAQĀMA, AND THE SHADOW PLAY
Authors: Monroe James , Pettigrew Mark
Published: May 2003

This article begins with a detailed structural analysis of "Zajal 90" by the Andalusī poet Ibn Quzmān (d. 555/1160). On the basis of this analysis, It is concluded that the poem employs irony to condemn the anti-Berber prejudice prevalent among native Andalusīs in Almoravid-ruled twelfth-century al-Andalus. It is also pointed out that the poem shares a number of key features with the maqāma genre, and may, in fact, be viewed as a maqāma in verse. The article then ascribes the invention of the maqāma genre by al-Hamadānī (358/969-398/1008) in the East, as well as its cultivation by al-Saraqustī (d. 538/1143) in the West, to two separate but parallel crises in literary patronage that took place (1) when the Persian-speaking Buwayhids reduced the Arab Abbāsid caliphs to puppets in Iraq (334/945), and (2) when the Berber-speaking Almoravids deposed the Arabic-speaking mulūk al-tawā if (448/1056) in al-Andalus. The article concludes by drawing a parallel between the above crises in literary patronage, and the rise of the shadow play, as it was cultivated by Ibn Dāniyāl (d. 710/1310), in late thirteenth-century Egypt, under the régime of the Mamlūk Sultan Baybars I (r. 658/1260-676/1277). Finally, the article attempts to illustrate how certain crises in literary patronage - resulting in the abandonment of the courtly, panegyrical qasīda - often led to extremely creative attempts at incorporating popular genres into the canon of formal Arabic literature.
THE PERFORMATIVITY OF IBN AL-MUQAFFA 'S KALĪLA WA-DIMNA AND AL-MAQĀMĀT AL-LUZŪMIYYA OF AL-SARAQUSTĪ
Authors: Wacks David
Published: May 2003

While not written for performance, works of medieval Arabic literature such as Ibn al-Muqaffa''s Kalīla wa-Dimna and al-Saraqustī's al-Maqāmāt al-luzūmiyya are extremely performative in nature, in that their structure is determined by representation of acts of performance. This is achieved either explicitly, by describing the performer or storyteller in the act of performing, or implicitly, by citing a performance carried out as part of a chain of narrative transmission, as in the isnād of a hadīt. The ways in which narrative performance is represented in these texts are reflective of the culture of performance and attitudes toward different types of performances that obtained in medieval Islam. Ibn al-Muqaffa' was a pioneer in the introduction of literary prose narrative to Arabic literature. He paved the way for later innovators such as al-Hamadhānī and al-Saraqustī, who brought literary fiction to Arabic literature by adapting traditionally accepted modes of oral narrative transmission into literary prose.
PREACHERS AND POETS: THE POPULAR SERMON IN THE ANDALUSĪ MAQĀMA
Authors: Young Douglas
Published: May 2003

This article examines the function of the popular sermon as represented in the Andalusī maqāma collection of Abū l-Tāhir Muhammad ibn Yūsuf al-Tamīmī al-Saraqustī. The popular sermon's representation in the maqāma became a standard feature of the genre with imaqāmāt of Hamadhānī. Hamadhani's use of the popular sermon for ironic effect and subversion of doctrine superposed the imaqāma's secular fictionality on the realm of religious doctrine and oratory. The popular sermon's representation thereafter became a generic convention of the maqāma in the corpora of Harīrī and his Andalusī successor, Saraqustī. Two texts, a critique of popular preaching by Ibn al-Djawzī and Ibn Djubayr's account of his own attendance at Ibn al-Djawzī's sermons, provide the historicized context for Saraqustī's and his predecessor's literary representations of popular sermonizing. The article concludes that, instead of being the mere epigone and imitator of his Eastern counterparts, Saraqustī uses the popular sermon's representation to create a distinctively Andalusī literary ethos.
"WORDS SWEETER THAN HONEY": THE GO-BETWEEN IN AL-SARAQUSTĪ'S "MAQĀMA 9"
Authors: Hamilton Michelle
Published: May 2003

This article focuses on the go-between character, Umm 'Amr, in "Maqāma 9" by the Andalusi writer al-Saraqustī, ibn al-Aštarkūwī (d. 1143). Umm 'Amr is one of the first literary manifestations of a character that continued to gain popularity in the medieval literature of the Iberian Peninsula, culminating in the figure of the old whore, Celestina, protagonist of the medieval Spanish work that bears her name. Elements common to the later Spanish tradition that appear in this maqāma are the go-between's avaricious personality, her rhetorical skills, and the context of lovesickness in which she operates. Umm 'Amr appears in the first part of "Maqāma 9" in the role usually played by the trickster al-Sadūsī. She initiates the trick by luring al-Sā'ib with her eyes and then enticing him with her speech. She makes promises, gives orations, composes poetry, and haggles. Umm 'Amr kindles al-Sā'ib's fire, and then promises to help him find a cure for his burning love, while all the time stringing him along and further enhancing his desire by talking of the beloved and giving him false hopes. Umm 'Amr is greedy, persuasive, and proud of her professional skills as a procuress in much the same way Celestina or Trotaconventos (the gobetween of the Libro de buen amor) is, and, like both those figures, Umm 'Amr is characterized as a potential healer of the protagonist's lovesickness.
Dancing on the Möbius Strip
Authors: BARTON BERNADETTE
Published: May 2003

The feminist sex wars have been characterized by debates between radical feminists and sex radical feminists about women's experiences of empowerment versus oppression in the sex industry. Based on a qualitative study of the experiences of exotic dancers, this article introduces a new theoretical paradigm to the feminist sex wars that values the contributions of both sex radicals and radical feminists. It articulates a twofold temporal dimension of sex workers' experiences: (1) how women's feelings of pleasure and empowerment gradually decline over time and (2) how good and bad experiences rapidly transform into their opposites over the course of a single evening, making the strip bar a volatile and unsettling space for performers.
“I Would Never Be a Secretary”
Authors: KENNELLY IVY
Published: May 2003

Gender affects us, but we also affect gender. This study reveals some of the ways women in two types of occupations—furniture sales and secretarial—shape the system of gender. As they struggle to define their identities within a segregated occupational structure, these women evoke notions of their differences from men and from other women, as well as their similarities to each group, in ways that are consistent with feminist theoretical positions on these issues. I argue that the ways these women define themselves have consequences for the shape of the system of gender. Many women inadvertently reinforce gender either by upholding traditional gender categories or by devaluing women. Yet some women create a powerful opportunity to dismantle gender by appreciating the work women have done and aligning themselves with these women to break out of staid gender categories.
Immigration and Women's Empowerment
Authors: ZENTGRAF KRISTINE M.
Published: May 2003

Recent discoveries that immigrant women often evaluate their experience more positively than men do have led to speculation that women view their public- and domestic-sphere status and power as having increased as a result of postimmigration employment outside of the home. This study, based on in-depth interviews with 25 Salvadoran women who migrated to Southern California in the 1970s and 1980s, challenges a unilinear, integrationist view that sees immigrant women's status and roles as changing along a traditional-modern continuum. Immigrant women's experiences and their perceptions of their experiences are quite diverse and complex. For many, paid employment outside of the home is not a new experience, and the household gender division of labor did not significantly change after migrating to the United States. However, women did report a sense of empowerment, newfound freedom, and selfconfidence as they negotiated traditional gender roles in a new social and cultural context.
Economic Security and the Social Science Literature on Teenage Pregnancy in South Africa
Authors: MACLEOD CATRIONA
Published: May 2003

Feminists have argued that the association made between teenage childbearing and long-term lower socioeconomic status hides a multitude of socially constructed inequalities. I extend this position by analyzing how the association is linked in the South African literature on teenage pregnancy to economic security. I utilize Foucault's conceptualization of the method of security. Security refers to institutions and practices that defend and maintain a national population as well as secure the economic, demographic, and social processes of that population. I analyze how the traits of the method of security are deployed with regard to teenage pregnancy; how reproductive adolescents are viewed as disrupting the production of the economic self and fracturing population control, thereby threatening economic security; and how the invocation of economic security allows for the legitimation of various regulatory practices.
Care Work
Authors: HERD PAMELA , MEYER MADONNA HARRINGTON
Published: May 2003

Scholars who debate the cause of and solutions for the decline in civic engagement have suggested that Americans have increasingly withdrawn from community organizations, reducing their political activity such as voting and interest in the political world, and generally failing to place the common good over individual self-interest. Their analyses are steeped in a tradition that is largely gender blind and consequently ignores care work. We infuse feminist analyses of paid labor and citizenship, which emphasize the merits and burdens of care work, into the civic engagement debate. We argue that care work, predominantly performed by women, paradoxically limits, enhances, and even constitutes a vital form of civic activity. We call for a fuller slate of social policies that will both redistribute the burden of care work and reinvigorate civic engagement.
“Click Here”
Authors: GOSSETT JENNIFER LYNN , BYRNE SARAH
Published: May 2003

Research on pornography has distinguished between its violent and nonviolent forms. Analyses of the content of violent pornography have largely focused on readily available soft-core images in adult films and magazines. However, current research has not adequately addressed pornography on the Internet. We show that discussions about violent pornography are incomplete without an understanding of the Internet as a unique and rapidly expanding medium for disseminating images of sexual violence against women. This article attempts to fill that gap by examining violent pornography using a sample of 31 free Internet sites. Each site was analyzed for its portrayal of women victims, male perpetrators, and its story of rape. Please be advised that the analysis contains graphic descriptions of violence toward women found on Internet rape sites.
Organizational Dynamics and Construction of Multiple Feminist Identities in the National Organization for Women
Authors: REGER JO
Published: May 2003

Through an analysis of two National Organization for Women chapters, the author finds that members construct multiple feminist identities that vary in collective definitions of feminism, the overall strategies adopted, and organizational culture. To explain these variations, the author analyzes meso-level relations between the organization and the environment, issues of diversity, and leadership continuity. This study illustrates how organizational factors intertwine to shape how participants come to view themselves and the political and cultural environment surrounding them. With the current research focus either on the larger political environment or individual characteristics, meso-level factors are often overlooked in examinations of social movement dynamics.
Plasma Sprayed Coatings with Water and Gas Atomised Bearing Steel Powders
Authors: Tsunekawa Y. , Ueno T. , Okumiya M. , Yashiro T.
Published: May 2003

The present paper investigates the characteristics of plasma sprayed coatings with water atomised bearing steel powder in comparison with gas atomised powder particularly focusing on oxidation during the spray process. As yet, there has been no research on the use of water atomised powders (characterised by non-spherical irregular appearance and high oxygen content) in plasma spraying on aluminium alloy substrate. The oxygen content increases beyond 10 wt-% in sprayed particles after fusion and resolidification in air although oxygen is only 0.20 wt-% of the as received water atomised powder. Sprayed particles are composed of α-Fe, γ-Fe, Fe1-xO and Fe3O4 after their heavy surface oxidation in flight. Coating examination shows wavy oxide phases at the interfaces between layered splats. Water atomised powder at a spray distance of 150 mm form coatings with an average oxygen content of 3.9 wt-%. At shorter spray distances, in both water and gas atomised powder coatings, the formed oxides almost disappear. The oxygen content of powder sprayed in an argon atmosphere does not increase and therefore, the oxidation mainly occurs during the droplet flight and is caused by oxygen captured in the plasma flame. If a shroud with argon shielding is installed in front of the gun tip to reduce oxygen mixed with the flame, it significantly reduces the oxidation during the droplet flight, especially at a longer spray distance.
Improvements on Surface Quality of EDMed Surfaces
Authors: Bayramoglu M. , Duffill A. W.
Published: May 2003

The traditional method of producing a free form shape by Electro discharge machining (EDM) is to produce the form on the tool and plunge this tool into the workpiece. One drawback however, is the cost and wear of these tools, particularly when producing complex shapes. CNC systems introduced on ram type machines, facilitates more sophisticated tool motions and the possibility of generating complex shapes with simple types of tools. Unlike the traditional EDM which uses 3D form tools, the use of simple tools causes a concentration of heat on the unwanted work piece material. Therefore, the characteristics of the surfaces obtained with simple tools could be different from the surfaces obtained in traditional EDM. In this work, the characteristics of EDMed surfaces obtained by simple tools are produced by measuring the surface roughness, heat affected zones, microcracks and microhardness. The results are then discussed and comparisons are made with 3D form tools.
Screening Wear Tester versus Hip Joint Simulator: Results of UHMWPE Sliding against Different CoCrMo Counterfaces
Authors: Gonzalez-Mora V. , Hoffmann M. , Chiesa R. , Cigada A. , Hampshire J. , Stroosnijder M. F.
Published: May 2003

The wear of ultra high molecular weight polyethylene (UHMWPE) articulating against different CoCrMo counterfaces was tested with unidirectional sliding motion using a reciprocating pin on flat machine (RPOF) in accordance with ASTM 732. The results were compared with wear data obtained from the same material combinations using a hip joint simulator (HJS) featuring a multidirectional sliding motion (biaxial rocking motion). There were three CoCrMo surfaces: a forged CoCrMo alloy (ISO 5832-12), which was subjected to an industrial mass finishing treatment, the same alloy with a hand polished surface finish and a CoCrMo coating applied to the forged CoCrMo alloy by magnetron sputtering physical vapour deposition. The results show that the linear reciprocating motion led to a deterioration of the PVD coating causing significantly higher UHMWPE wear compared to the mass finished and hand polished forged CoCrMo alloy. However, the same CoCrMo coating caused significantly less UHMWPE wear than the forged CoCrMo alloys in the HJS. These results highlight the importance of selecting the correct choice of sliding motion, suggesting that this type of coating may be promising for applications in which multidirectional sliding predominates, for example, as a coating on femoral heads in artificial hip joints.
What effects do mineral particles have in the lung?
Authors: Richards R.
Published: May 2003

This review details a selection of occupational lung diseases, particularly fibrosis (scarring) and tumours that can arise following exposure to mineral dusts. Also described are the sequential repair processes of the lung including oedema, inflammation, epithelial changes and finally scarring. The features by which a dust can be considered bioreactive including shape, size, surface area, durability and surface chemistry is discussed together with the importance of the mass deposited in the lung and particle clearance, particularly through lymphatic drainage. Emphasis is given to the importance of surface chemistry in that crystalline minerals, especially silicas, are often highly bioreactive whereas amorphous silicas or crystalline forms that have aged in the laboratory have lesser activity. Nevertheless, all forms of crystalline silica are particularly hazardous with the long-term ability to produce irreversible disease (fibrosis) when administered to experimental animals.
Toxicity of airborne dust generated by opencast coal mining
Authors: Reynolds L. , Jones T. P. , Beérubeé K. A. , Wise H. , Richards R.
Published: May 2003

Experiments were undertaken to determine the toxicity in the lung of dust generated by opencast coal mining. Since it was impractical to collect the large mass of actual opencast respirable dust required for the toxicity experiment, a surrogate dust with the same size distribution was manufactured (PSW). This surrogate dust had the same basic mineralogical composition as mineralogically characterized airborne dust collected from the welsh coal opencast pit at Park Slip West. Diesel exhaust particles (DEP), generated from mining vehicular and mechanical activity, contribute towards opencast particulate matter. Therefore, a second dust comprising of a 50/50 by weight mixture of the surrogate mineral dust and diesel soot was also examined (PSW + DEP). These dusts and DEP (weak biological reactivity) and a-quartz (high biological reactivity) were instilled into the lungs of healthy rats. The animals were sacrificed at 1, 6 and 11 weeks. Assessments of potential toxicity included lung to body weight ratios, acellular protein in lung lavage (markers of lung permeability) and total free cells (marker of inflammation). The surrogate opencast dust with or without DEP caused no significant increases in any of the parameters studied and as such was very similar to the weak biological effects of DEP alone. These effects contrasted sharply with those observed for the bioreactive mineral, quartz that induced rapid increases in permeability and a progressive inflammation. The use of a surrogate is less desirable then the real opencast mine dust, however, if as believed, the surrogate material is a representative mixture of the actual airborne dust around this opencast site, then these particles should show little or no short-term lung toxicity following inhalation.
Primary blasting in a limestone quarry: physicochemical characterization of the dust clouds
Authors: Jones T. , Morgan A. , Richards R.
Published: May 2003

Airborne dust generated by primary blasting was collected in Taffs Well Quarry, just north of Cardiff, Wales. Collections of airborne particulate matter were also made in the nearby village of Morganstown at the same time as the blasting collections. The explosions were recorded on a motor-driven camera and a digital video camera. These images show that the dust clouds generated by the explosions consist of three distinct components; a reddish-grey dust cloud, followed by a light grey dust cloud, and finally a pale grey cloud that stayed near the blast face. It is believed that the reddish-grey cloud was composed mostly of mineral grains, as evidenced by the chiefly red colour of the dolomitic limestone rock in the quarry. The whiter clouds contained more explosive combustion particles (diesel soot). The samples were studied by analytical scanning electron microscopy, very high-resolution field emission scanning electron microscopy, and image analysis. The two different components (minerals and diesel soot) can be readily seen under high-resolution electron microscopy. Any consideration of the possible adverse health effects or nuisance value of this dust needs to consider both of these components. A size distribution of the quarry particles shows that soot particles dominate the assemblage under 2 mm, whereas the mineral grains are more abundant over 2 mm. This contrasts with the Morganstown particle sizes, where the two components show similar size distributions. The determination of the mineralogy of the quarry dust and Morganstown particles has shown highly complex and heterogeneous mixtures, though some distribution patterns are emerging. It is concluded that much of the dust in Morganstown probably originated from sources other than the quarry, such as other local industries, roads and construction sites.
Airborne particulate matter (PM10) in the china clay area, Cornwall, UK
Authors: Parsons B. , Salter L. , Coe T. , Mathias R. , Richards R. J. , Jones T. P.
Published: May 2003

Work was undertaken in 1997 as part of a UK government programme to monitor air quality in the Cornish china clay area. These studies showed that concentrations of airborne particulate matter with an aerodynamic diameter <10 μm (PM10) did not exceed UK National Air Quality Strategy (NAQS, 1995) guidelines but were, however, greater than those normally associated with rural areas. Subsequently, in the summer of 2000, airborne dust sampling was conducted at three sites around the IMERYS (formerly ECCI) Kernick mica dam, a potential source of resuspended airborne particulates from china clay waste minerals. Analytical scanning electron microscopy examination of the collected material suggested that up to 61% of the airborne PM10 monitored next to the mica dam could be associated with china clay extraction compared with 46% 2 km to the south. Results showed the presence of substantial percentages of respirable kaolinite, muscovite and quartz; the major components of china clay waste. The health effects of the particular mineral dust emissions associated with china clay mining are reviewed.
Identification and characterization of radioactive ‘hot’ particles in Chernobyl fallout-contaminated soils: the application of two novel approaches
Authors: Entwistle J. A. , Flowers A. G. , Nageldinger G. , Greenwood J. C.
Published: May 2003

The Chernobyl accident in 1986 resulted in the widespread identification of the post-accident presence of radioactive (or ‘hot’) particles across large areas of Eastern and Central Europe. Such particles arise from direct deposition and also from condensation and interactions on particle surfaces during and following the deposition of soluble fallout. Identification of the presence and nature of hot particles is necessary in order to determine the long-term ecological impact of radioactive fallout. This paper describes several techniques for the identification and characterization of hot particles in soil samples from Belarus. In addition to new results from the use of gamma spectrometry, we include two novel instrumentation approaches that have been developed and applied to Chernobyl fallout-contaminated soils. The first, ‘differential’ autoradiography, utilizes a photographic film sandwich to characterize the nature of the ionizing radiation emitted from samples. In this paper we show that differential autoradiography can not only identify hot particle presence in soil, but can also determine the dominant radionuclide in that particle. The second approach, sector field ICP-MS (ICP-SFMS), can provide rapid, high-precision determination of the actinides, including the transuranic actinides, that characteristically occur in hot particles originating from weapons fallout or fuel matrices. Here, ICP-SFMS is shown to yield sufficiently low detection limits for plutonium isotopes (with the exception of 238Pu) to enable us to confirm negligible presence of plutonium in areas outside the Chernobyl exclusion zone, but with high levels of fission-product contamination.
Sources, mineralogy, chemistry and fate ofheavy metal-bearing particles in mining-affected river systems
Authors: Hudson-Edwards K. A.
Published: May 2003

Heavy metal-bearing sediment particles enter river systems by discharge of mine or processing waste, tailings dam failures, remobilization of mining-contaminated alluvium and mine drainage. The mineralogy and geochemistry of these particles is dependent upon the original ore mineralogy, and on processes that have occurred in the source areas, during transport and deposition and during postdepositional early diagenesis. This paper reviews the research carried out to date on the sources, mineralogy, chemistry and fate of heavy metal-bearing particles in mining-affected river systems, and identifies six important avenues for further investigation.
Evaluation of computer-controlled SEM in the study of metal-contaminated soils
Authors: Langmi H. W. , Watt J.
Published: May 2003

Computer-controlled scanning electron microscopy (CCSEM) has been assessed for the determination of form and size distribution of heavy metals in urban contaminated soils. Metal distributions within individual particles were determined using X-ray element mapping. The sites selected for study were (1) around a landfill site, previously a colliery in Wolverhampton, UK and (2) a private garden adjacent to a railway in Nottingham, UK. Backscattered thresholding techniques were used to isolate the Pb-containing categories. The classification results for both Wolverhampton and Nottingham soils were generally similar but more Pb-containing classes were observed for the Nottingham samples when a comparison was made between results of the same size fractions. However, difficulties with the technique arose when particles showing chemically similar weathering crusts were assigned to the same class, despite having different internal compositions. The CCSEM data therefore need to be interpreted with caution and their application limited to situations in which particle internal complexity is not an issue.
The aqueous geochemistry of metals in the weathering environment: strengths and weaknesses in our understanding of speciation and process
Authors: Curtis C. D.
Published: May 2003

Soil profiles developed in different climates and physical settings are highly variable in structure, in mineralogy, in the local biosphere and in the compositions of the soil gas and water phases. Discussion of metals in ‘the weathering environment’ needs to acknowledge and address this diversity.

The thermochemical methods developed by Pourbaix (1949) and Garrels and Christ (1965) remain useful predictors of metal speciation and solubility but the approach is valid only for processes involving carbonates, sulphides, hydroxides and similar minerals in soils and sediments. Almost no primary silicates are thermodynamically stable: they spontaneously decompose to non-equilibrium solid products with metal release determined by kinetics.

Hydrolysis constants for aquo-complexes are useful indicators of metal speciation, mobility and availability. Recent work on soluble soil organic matter confirms that the active ligands are overwhelmingly oxygen based: phenols, carboxylic acids, alcohols. Many of these molecules compete very effectively with aquo-complexes to form strong metal chelates and appear to be responsible for substantial Al and Fe mobilization within and translocation down soil profiles.

It is important to note also that strong clay mineral/organic matter associations (clay-organic complex) will fix metals as a consequence of the same chelation reactions (in this case removing them from solution - retardation).
IC-ICP-MS and IC-ICP-HEX-MS determination of arsenic speciation in surface and groundwaters: preservation and analytical issues
Authors: Polya D. A. , Lythgoe P. R. , Abou-Shakra F. , Gault A. G. , Brydie J. R. , Webster J. G. , Brown K. L. , Nimfopoulos M. K. , Michailidis K. M.
Published: May 2003

Understanding the biogeochemical behaviour of arsenic in the weathering and shallow subsurface environment depends critically upon determining the nature and distribution of the chemical species present in natural waters. To this end, coupled ion chromatography-inductively coupled plasma mass spectrometry (IC-ICP-MS) is widely used, though species fractionation during ultrasonic nebulization, and matrix-dependent ionization in the plasma are analytical issues that need to be addressed. Hexapole collision cell technology is shown to be effective in suppressing chloride-based polyatomic interferences. Irrespective of the analytical technique used, As(III)/As(V) ratios of natural waters may change substantially during storage due to (1) differential adsorption of arsenic species on hydrated ferric oxides (HFOs); and (2) microbial activity. A wide range of apparently contradictory speciation changes observed by various workers can be rationalized in terms of the differences of microbial consortia present in different water samples. Arsenic speciation in certain water types can be stabilized for days or even weeks by combined filtration, acidification and refrigeration whilst the addition of EDTA and the use of 0.1 mm filters is indicated for iron-rich waters and waters with high activities of redox-active bacteria, respectively. Although the use of hydrochloric acid has been reported elsewhere as resulting in the apparent oxidation of As(III), we show that for certain water types it acts as an extremely effective preservative of arsenic speciation.