bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal Deixis in Colonial Chontal and Maya Hieroglyphic Narrative
Authors: Wald Robert F.
Published: October 2007

Comparison of a set of Colonial Acalan Chontal documents with inscriptions of the Classic period reveals that a deictic enclitic -ihi or -iji(y) occurs on verbs in similar contexts in both bodies of texts. Certain forms of this clitic have been interpreted elsewhere as inflection for aspect, or as a different temporal clitic from that proposed here. This investigation confirms that the element is an adverbial clitic, and thus allows its identification in otherwise unrecognized instances. While serving as an integral part of the discourse pattern, it also helps demarcate more clearly the lines between aspect and time in the verb systems under study. In a broader view, this proposal carries implications both for the nature of Classic Maya historical narrative and for the identity of the languages in which it was written.
Phonetic Borrowing
Authors: Li David C.S.
Published: October 2007

Chinese Hongkongers express themselves increasingly in written Cantonese, resulting in the proliferation of Cantonese elements in the Hong Kong Chinese press. To overcome the orthographic gap, Hongkongers resort to phonetic borrowing and phonetic compound formation. Phonetic borrowing may be based on modern standard Chinese or on English. Script mixing is very common, suggesting that linguistic convergence has taken place. Eighteen months after the British handover to the People’s Republic of China, this situation remains unchanged. Standardization of Cantonese is desirable, but will be difficult to enforce. Despite the vitality of written Cantonese in Hong Kong, this paper argues against promoting Cantonese to the status of an official language.
Symbols Make Text
Authors: Kenner Charmian
Published: October 2007

Research on early script-learning has shown that young children produce a considerable variety of graphic forms in their spontaneous writing. Social semiotic theory aims to account for this variety by analysing the links between children’s sociocultural experience and their interpretation of written language as a visual sign system. This paper applies a social semiotic approach to a multilingual context, discussing texts produced by three- and four-year-olds in a nursery class, where the roleplay area was enriched with everyday literacy materials and parents were invited to write in different languages in the classroom. Evidence from a year’s fieldwork showed that children used a diversity of symbols throughout this period. Three factors were found to have explanatory significance: (a) awareness of the visual appearance of different types of text, (b) children’s current symbolic repertoire, and (c) their social identity as writers. Multilingual experience was incorporated into children’s exploration of how writing operated as a representational system.
What do “phonemic” writing systems represent?
Authors: Ratcliffe Robert R.
Published: October 2007

The traditional classification of phonemic writing systems into three types — syllabaries, consonantal scripts, and alphabets — is based on a phonological theory which recognizes only the syllable and the segment as potential units of representation. It is argued here that an accurate typology of phonemic writing systems requires recognition of two further dimensions of phonological structure: phonological time, and the sonority hierarchy. The analysis focuses on two “typical” non-alphabetic systems — Japanese kana and the Arabic script, the former traditionally classed as a syllabary, the latter as a consonantal script. It is argued that the two scripts in fact share a common organizational principle, namely the iconic representation of phonological time.
Language policy and reforms of writing systems for minority languages in China
Authors: Zhou Minglang
Published: October 2007

This paper examines how China’s language policy, dictated by its ethnic minorities policy, has influenced reforms of writing systems for minority languages since 1949. Measured by the landmark publication of the Plan for the Phonetic Spelling of Chinese in 1957, reforms of minority writing systems can be divided into three stages. The pre-Plan stage featured efforts to match written and oral languages, and Russian influence including introduction of the Cyrillic script. During the Plan-oriented stage, romanization ruled not only the creation of new writing systems for oral languages, but also the reform of existing non-roman systems. The relatively Plan-independent stage, ushered in by standardization of the Yi writing system in a Siniform script, has opened the door, though only narrowly, to “native” writing systems. Examined from an international perspective, China’s language policy has undergone the same waxing and waning of assimilation and accommodation as those of industrialized and developing countries; but the Chinese experience demonstrates both the advantages and disadvantages of direct government involvement in minority language maintenance and development.
Orthography and identity in Cameroon
Authors: Bird Steven
Published: October 2007

The tone languages of sub-Saharan Africa raise challenging questions for the design of new writing systems. Marking too much or too little tone can have grave consequences for the usability of an orthography. Orthography development, past and present, rests on many sociolinguistic issues having little to do with the technical phonological concerns that usually preoccupy orthographers. Some of these issues are familiar from the spelling reforms which have taken place in European languages. However, many of the issues faced in sub-Saharan Africa are different, being concerned with the creation of new writing systems in a multi-ethnic context — involving residual colonial influences, the construction of new nation-states, detribalization vs. culture preservation and language reclamation. Language development projects which crucially rely on creating or revising orthographies may founder if they do not attend to the various layers of identity (colonial, national, ethnic, local, or individual) that are indexed by orthography. This study reviews the history and politics of orthography in Cameroon, with a focus on tone-marking. The article concludes by calling present-day orthographers to a deeper and broader understanding of orthographic issues.
(Il)literacy and (im)morality in Bernhard Schlink’s The reader
Authors: Johnson Sally , Finlay Frank
Published: October 2007

This paper explores the theme of literacy in a recent novel, The reader, by the German author Bernhard Schlink. Drawing both on literary analysis and on the insights of the “new literacy studies”, the paper argues that the depiction of illiteracy contained in the novel is problematical in two main ways. First, there are a number of textual inconsistencies regarding the definition and portrayal of illiteracy. Second, the novel provides a questionable account of the relationship between literacy and an individual’s capacity for moral and aesthetic judgement, especially in the context of debates about the Holocaust. We are therefore skeptical of the way in which The reader has been enthusiastically held up as a realistic account of illiteracy and its potential consequences, not least by Sir Claus Moser in Improving literacy and numeracy: A fresh start (1999), a report on “basic skills” produced for the Department of Education and Employment in the UK.
Passive voice constructions in written texts
Authors: Jisa Harriet , Reilly Judy , Verhoeven Ludo , Baruch Elisheva , Rosado Elisa
Published: October 2007

The distribution of passive constructions is examined in written texts produced by native speakers of five Languages (Dutch, English, French, Hebrew, and Spanish), from four Age groups (aged 9–10, 12–13, 15–16 years, and adults). These languages contrast in the variety of structures available to promote a patient and to downgrade an agent in event encoding. The results show significant effects of Language and Age. When a language has productive alternative rhetorical options for the two functions, it relies less on passive constructions. Across all five languages, passives increase with Age. However, even our youngest subjects show a language-specific rhetorical bias.
Propositional attitudes in written and spoken language
Authors: Reilly Judy , Baruch Elisheva , Jisa Harriet , Berman Ruth A.
Published: October 2007

This study considers the use of modal expressions (auxiliaries like should
,
can), semi-modals (e.g. have to, be likely to), and adverbials and complement-taking expressions (maybe, it is possible that ) to convey the attitudes and feelings of speaker/writers about the events they describe and the ideas they express. The topic of “propositional attitudes” thus overlaps with the domains of linguistic analysis known as “mood and modality.” This paper considers selected facets of linguistic modality in developmental and cross-linguistic perspective.
Form and function of emotive pictorial signs in casual letter writing
Authors: Kataoka Kuniyoshi
Published: October 2007

Young Japanese women effectively construct and manipulate their emotive stances through the use of special pictorial signs and their graph(em)ic modifications in casual letter-writing among friends. To achieve this, the writers use a para-/metalinguistic and indexical means of “contextualization” for the socio-cultural mediation of affect and textual awareness. At the same time, they heavily rely on such cognitive mechanisms as “schematization” and “semantic reduction” — phenomena widely observed in grammaticalization processes. I propose that these devices not only provide the basis for mutual appreciation of the emotive (con)text, but also suggest a mode of literacy aimed primarily at emotive, phatic, and poetic communication.
Letter-writing in French Louisiana
Authors: Dubois Sylvie
Published: October 2007

This article reports a sociolinguistic analysis of the French spelling system in newly discovered, authentic personal letters written by literate settlers living in Louisiana during the 18th and 19th centuries. After showing that French and non-French vernaculars were very much alive among the Louisiana founding population, the paper examines the use of old and new French norms in Louisiana for three socio-economic classes over time: the elite, planter, and military/merchant populations. Socio-demographic pressures are described that could have led to the maintenance of old French features or the expansion of some French varieties. It is shown that the history of French spelling in France, the origins of diverse migrant populations that settled in colonial Louisiana, and the powerful socio-economic events that shape the expansion of a socially well-delineated population not only explain the linguistic behavior of both French settlers and Louisiana-born writers, but also provide many hints to determining the sociolinguistic attributes of the illiterate French vernacular-speaking population.
Determining summer residence status and vertical habitat use of sailfish (Istiophorus platypterus) in the Arabian Gulf
Authors: Hoolihan John P. , Luo Jiangang
Published: October 2007

Hoolihan, J. P. and Luo, J. 2007. Determining summer residence status and vertical habitat use of sailfish (Istiophorus platypterus) in the Arabian Gulf. – ICES Journal of Marine Science, 64. Pop-up satellite archival tags (PSATs) were deployed on 18 sailfish in the Arabian Gulf between 2001 and 2005 to determine summer geoposition and habitat preference. Programmed releases following periods ranging from 110 to 156 d provided an aggregate total of 533 monitoring days of data. Three PSATs failed to report and nine released prematurely after periods ranging from 3 to 93 d. Four were recovered in gillnets after periods ranging from 39 to 90 d, and two transmitted after programmed releases of 127 and 128 d. Pooled archival data from recovered PSATs showed a cumulative mean distribution of 83.9% for total time spent in the upper 10 m, with no significant difference between day and night (χ24 = 0.84, p = 0.93). Depth ranged from 0 to 61 m, and ambient water temperature from 19.7°C to 30.1°C. Linear displacements ranged from 11 to 543 km and were all located inside the Gulf. Satellite- and light-level-derived geopositioning suggested that all fish remained in the Gulf. The two PSATs releasing on schedule validated summer residence inside the Gulf, providing further evidence in support of genetic analyses and conventional mark-recapture studies, which suggested that this billfish population confines itself year-round within a shallow marginal sea area. Preference for near-surface depths suggests a great susceptibility to capture by gillnets and other surface gears, raising concern for the effectiveness of regional management and conservation of the species.
Receiver bias for exaggerated signals in honeybees and its implications for the evolution of floral displays
Authors: Naug Dhruba , Arathi H.S
Published: October 2007

Mechanistic models of animal signals posit the occurrence of biases on the part of receivers that could be potentially exploited by signallers. Such biases are most obvious when animals are confronted with exaggerated versions of signals they normally encounter. Signalling systems operating in plant–pollinator interactions are among the most highly coevolved, with plants using a variety of floral signals to attract pollinators. A number of observations suggest that pollinators preferentially visit larger floral displays although the benefit of this to either the plant or the pollinator is not always clear. We use a standard dual-choice experimental protocol to show that honeybees display a receiver bias for exaggerated size and colour contrast—two important components of floral signals—even when such signals do not indicate quality. We discuss the implications of this receiver bias for the evolution of floral displays and its possible exploitation by invading alien plants.
Context-dependent genetic benefits of polyandry in a marine hermaphrodite
Authors: Marshall Dustin J , Evans Jonathan P
Published: October 2007

Numerous studies emphasize the potential indirect (genetic) benefits of polyandry in animals with resource-free mating systems. In this paper, we examine the potential for these benefits to fuel sexual selection and polyandry in the hermaphroditic ascidian
Pyura stolonifera
. Individuals were designated either sire (sperm producers) or dam (egg producers) at random and crossed in a North Carolina II breeding design to produce both paternal and maternal half siblings for our quantitative genetic analysis. We then partitioned the phenotypic variance in fertilization and hatching rates into additive and non-additive variance components. We found significant additive variance attributable to sire and dam effects at fertilization and hatching, suggesting the potential for selection to favour individuals carrying intrinsically ‘good genes’ for these traits. In separate analyses involving monandrous and polyandrous clutches, we found that both traits were elevated under polyandry, but the difference in hatching rates was due entirely to the difference in fertilization rates between treatments. When the hatching rates were standardized to account for variance at fertilization, there was no overall net benefit of polyandry for this trait. Despite this, we found that hatching success declined with increasing embryo densities, and that the slope of this decline was significantly greater in monandrous than polyandrous clutches. Hence, selection on embryo viability may still favour polyandry under restricted environmental conditions. Nevertheless, our results caution against interpreting elevated hatching success as an indirect genetic benefit of polyandry when variance in fertilization is not controlled.
Heterospecific alarm call recognition in a non-vocal reptile
Authors: Vitousek Maren N , Adelman James S , Gregory Nathan C , Clair James J. H. St
Published: October 2007

The ability to recognize and respond to the alarm calls of heterospecifics has previously been described only in species with vocal communication. Here we provide evidence that a non-vocal reptile, the Galápagos marine iguana (Amblyrhynchus cristatus), can eavesdrop on the alarm call of the Galápagos mockingbird (Nesomimus parvulus) and respond with anti-predator behaviour. Eavesdropping on complex heterospecific communications demonstrates a remarkable degree of auditory discrimination in a non-vocal species.
Stochastic fluctuations in epidemics on networks
Authors: Simões M , Telo da Gama M.M , Nunes A
Published: October 2007

The effects of demographic stochasticity on the long-term behaviour of endemic infectious diseases have been considered for long as a necessary addition to an underlying deterministic theory. The latter would explain the regular behaviour of recurrent epidemics and the former the superimposed noise of observed incidence patterns. Recently, a stochastic theory based on a mechanism of resonance with internal noise has shifted the role of stochasticity closer to the centre stage, by showing that the major dynamic patterns found in the incidence data can be explained as resonant fluctuations, whose behaviour is largely independent of the amplitude of seasonal forcing, and by contrast very sensitive to the basic epidemiological parameters. Here we elaborate on that approach, by adding an ingredient which is missing in standard epidemic models, the ‘mixing network’ through which infection may propagate. We find that spatial correlations have a major effect on the enhancement of the amplitude and the coherence of the resonant stochastic fluctuations, providing the ordered patterns of recurrent epidemics, whose period may differ significantly from that of the small oscillations around the deterministic equilibrium. We also show that the inclusion of a more realistic, time-correlated recovery profile instead of exponentially distributed infectious periods may, even in the random-mixing limit, contribute to the same effect.
On the elastohydrodynamic analysis of shear-thinning fluids
Authors: Jang J.Y , Khonsari M.M , Bair S
Published: October 2007

Realistic prediction of the characteristics of the elastohydrodynamic lubrication (EHL) contact requires consideration of the appropriate constitutive equation for the lubricant. In many applications, the lubricant exhibits a shear-thinning behaviour which significantly affects the film thickness. In this paper, we present a generalized formulation that can efficiently treat shear-thinning fluids with provision for compressibility in the EHL line contact. Specifically, the Carreau model and the sinh-law model are investigated. An extensive set of numerical solutions and comparison with experiments reveal that the Carreau equation properly captures the film thickness behaviour under both rolling and sliding conditions.
Bounds for the torsional rigidity of shafts with arbitrary cross-sections containing cylindrically orthotropic fibres or coated fibres
Authors: Chen Tungyang , Lipton Robert
Published: October 2007

In this paper we derive bounds for the torsional rigidity of a cylindrical shaft with arbitrary transverse cross-section containing a number of cylindrically orthotropic fibres or coated fibres. The exact upper and lower bounds depend on the constituent shear rigidities, the area fractions, the locations of the reinforcements as well as the geometric shape of the cross-sections. Specific bounds are derived for circular shafts, elliptical shafts and cross-sections of equilateral triangle. Simplified expressions are also deduced for reinforcements with isotropic constituents. We verify that when additional constraints between the constituent properties of the phases are fulfilled, the upper and lower bounds will coincide. In the latter case, the fibres or coated fibres become neutral under torsion and the bounds recover the previously known exact torsional rigidity.
Multi-fidelity optimization via surrogate modelling
Authors: Forrester Alexander I.J , Sóbester András , Keane Andy J
Published: October 2007

This paper demonstrates the application of correlated Gaussian process based approximations to optimization where multiple levels of analysis are available, using an extension to the geostatistical method of
co-kriging
. An exchange algorithm is used to choose which points of the search space to sample within each level of analysis. The derivation of the co-kriging equations is presented in an intuitive manner, along with a new variance estimator to account for varying degrees of computational ‘noise’ in the multiple levels of analysis. A multi-fidelity wing optimization is used to demonstrate the methodology.
Fighting for shells: how private information about resource value changes hermit crab pre-fight displays and escalated fight behaviour
Authors: Arnott Gareth , Elwood Robert W
Published: October 2007

Pre-fight displays typically provide honest, but sometimes dishonest, information about resource holding potential and may be influenced by assessment of resource value and hence motivation to acquire the resource. These assessments of potential costs and benefits are also predicted to influence escalated fight behaviour. This is examined in shell exchange contests of hermit crabs in which we establish an information asymmetry about a particularly poor quality shell. The poor shell was created by gluing sand to the interior whereas control shells lacked sand and the low value of the poor shell could not be accurately assessed by the opponent. Crabs in the poor shell showed changes in the use of pre-fight displays, apparently to increase the chances of swapping shells. When the fights escalated, crabs in poor shells fought harder if they took the role of attacker but gave up quickly if in the defender role. These tactics appear to be adaptive but do not result in a major shift in the roles taken or outcome. We thus link resource assessment with pre-fight displays, the roles taken, tactics used during escalation and the outcome of these contests.
Sex-dependent up-regulation of two splicing factors, Psf and Srp20, during hippocampal memory formation
Authors: Antunes-Martins Ana , Mizuno Keiko , Irvine Elaine E. , Lepicard Eve M. , Giese K. Peter
Published: October 2007

Gene transcription is required for long-term memory (LTM) formation. LTM formation is impaired in a male-specific manner in mice lacking either of the two Ca2+/calmodulin-dependent kinase kinase (Camkk) genes. Since altered transcription was suggested to cause these impairments in LTM formation, we used microarrays to screen for CaMKKβ-dependent gene expression changes. Here we show that the hippocampal mRNA expression of two splicing factors, splicing factor arginine/serine-rich 3 (Sfrs3/Srp20) and polypyrimidine tract-binding protein-associated splicing factor (Psf), is altered in CaMKKβ-deficient males. In wild-type (WT) mice, the basal expression level in the hippocampus is higher in males than in females, and the sex difference in Srp20 expression is detectable before puberty. Training in two hippocampus-dependent learning tasks, the spatial version of the Morris water maze (MWM) and background contextual fear conditioning, increases the hippocampal mRNA expression of both splicing factors in WT males. However, the increase in Srp20 mRNA expression occurs only in males and not in females, whereas the up-regulation of Psf expression occurs in both sexes. Importantly, control experiments demonstrate that the up-regulation of both splicing factors is specific for the learned associations after contextual fear conditioning. In summary, we provide the first evidence for a regulation of splicing factors during LTM formation and we suggest that alternative splicing contributes to sex differences in LTM formation.
The neural correlates of conceptual and perceptual false recognition
Authors: Garoff-Eaton Rachel J. , Kensinger Elizabeth A. , Schacter Daniel L.
Published: October 2007

False recognition, broadly defined as a claim to remember something that was not encountered previously, can arise for multiple reasons. For instance, a distinction can be made between conceptual false recognition (i.e., false alarms resulting from semantic or associative similarities between studied and tested items) and perceptual false recognition (i.e., false alarms resulting from physical similarities between studied and tested items). Although false recognition has been associated with frontal cortex activity, it is unclear whether this frontal activity can be modulated by the precise relationship between studied and falsely remembered items. We used event-related fMRI to examine the neural basis of conceptual compared with perceptual false recognition. Results revealed preferential activity in multiple frontal cortex regions during conceptual false recognition, which likely reflected increased semantic processing during conceptual (but not perceptual) memory errors. These results extend recent reports that different types of false recognition can rely on dissociable neural substrates, and they indicate that the frontal activity that is often observed during false compared with true recognition can be modulated by the relationship between studied and tested items.
Time of day accounts for overnight improvement in sequence learning
Authors: Keisler Aysha , Ashe James , Willingham Daniel T.
Published: October 2007

The theory that certain skills improve with a night of sleep has received considerable interest in recent years. However, because sleep typically occurs at the same time of day in humans, it is difficult to separate the effects of sleep from those of time of day. By using a version of the Serial Response Time Task, we assessed the role of sleep in implicit sequence learning while controlling for possible time-of-day effects. We replicated the apparent benefit of sleep on human participants. However, our data show that sleep does not affect implicit sequence learning; rather, time of day affects the ability of participants to express what they have learned.
Stream fish assemblage and habitat structure in a tropical African river basin (Nyagui River, Zimbabwe)
Authors: Kadye Wilbert T. , Moyo Ngonidzashe A. G.
Published: October 2007

Few studies have been carried out on stream ecology in southern Africa although many species are endangered. This study investigated the stream fish assemblage and their habitat associations over a period of 3 months (October 2004 to January 2005), in view of the proposal to build a dam across the Nyagui River. Twenty‐four fish species were collected and were separated into groups based on preferred microhabitats. The first group, dominated by Barbus paludinosus, comprised species collected from the upstream stations with slow flow, shallow depth (pools) and fine substrate type. Species associated with riffles, which included Chiloglanis neumanni, Labeobarbus marequensis and Opsaridium zambezense, comprised the second group on the downstream. The last group comprised species preferring pools with rock substrate and slow flow such as Pharyngochromis acuticeps and Pseudocranilabrus philander. The species were consistently associated with their habitat types throughout the sampling period. This relationship may be explained by the fish’s morphological adaptations. Species richness increased from nine in the upstream section to twenty in the downstream section and this was related to increasing habitat complexity downstream. The construction of the Kunzvi Dam across the Nyagui River is likely to lead to loss of rheophilic species while cichlids and introduced species may increase.
Contrasting transient and steady‐state rivers crossing active normal faults: new field observations from the Central Apennines, Italy
Authors: Whittaker Alexander C. , Cowie Patience A. , Attal Mikaël , Tucker Gregory E. , Roberts Gerald P.
Published: October 2007

We present detailed data on channel morphology, valley width and grain size for three bedrock rivers crossing active normal faults which differ in their rate, history and spatial distribution of uplift. We evaluate the extent to which downstream changes in unit stream power correlate with footwall uplift, and use this information to identify which of the channels are likely to be undergoing a transient response to tectonics, and hence clarify the key geomorphic features associated with this signal. We demonstrate that rivers responding transiently to fault slip‐rate increase are characterised by significant long‐profile convexities (over‐steepened reaches), a loss of hydraulic scaling, channel aspect ratios which are a strong non‐linear function of slope, narrow valley widths, elevated coarse‐fraction grain‐sizes and reduced downstream variability in channel planform geometry. We are also able to quantify the steady‐state configurations of channels, that have adjusted to differing spatial uplift fields. The results challenge the application of steady‐state paradigms to transient settings and show that assumptions of power‐law width scaling are inappropriate for rivers, that have not reached topographic steady state, whatever exponent is used. We also evaluate the likely evolution of bedrock channels responding transiently to fault acceleration and show that the headwaters are vulnerable to beheading if the rate of over‐steepened reach migration is low. We estimate that in this setting the response timescale to eliminate long‐profile convexity for these channels is ∼1 Myr, and that typical hydraulic scaling is regained within 3 Myr.
Gene expression profiling of CD34+ cells in patients with the 5q− syndrome
Authors: Boultwood Jacqueline , Pellagatti Andrea , Cattan Helen , Lawrie Charles H. , Giagounidis Aristoteles , Malcovati Luca , Porta Matteo G. Della , Jädersten Martin , Killick Sally , Fidler Carrie , Cazzola Mario , Hellström‐Lindberg Eva , Wainscoat James S.
Published: October 2007

The transcriptome of the CD34+ cells was determined in a group of 10 patients with the 5q− syndrome using a comprehensive array platform, and was compared with the transcriptome of CD34+ cells from 16 healthy control subjects and 14 patients with refractory anaemia and a normal karyotype. The majority of the genes assigned to the commonly deleted region (CDR) of the 5q− syndrome at 5q31–q32 showed a reduction in expression levels in patients with the 5q− syndrome, consistent with the loss of one allele. Candidate genes showing haploinsufficiency in the 5q− syndrome included the tumour suppressor gene SPARC and RPS14, a component of the 40S ribosomal subunit. Two genes mapping to the CDR, RBM22 and CSNK1A1, showed a >50% reduction in gene expression, consistent with the downregulation of the remaining allele. This study identified several significantly deregulated gene pathways in patients with the 5q− syndrome and gene pathway analysis data supports the proposal that SPARC may play a role in the pathogenesis of the 5q− syndrome. This study suggests that several of the genes mapping to the CDR of the 5q− syndrome play a role in the pathogenesis of this disorder.
The plant mannose‐binding lectin NTL preserves cord blood haematopoietic stem/progenitor cells in long‐term culture and enhances their ex vivo expansion
Authors: Li Karen , Ooi Vincent E. C. , Chuen Carmen Ka Yee , Lam Audrey Carmen , Ooi Linda Shiou Mei , Zhang Xiao Bing , Tsang Kam Sze , Chiu Lawrence Chi Ming , Chan Kathy Yuen Yee , Li Chi Kong , Fok Tai Fai , Yuen Patrick Man Pan , Ng Pak Cheung
Published: October 2007

Ex vivo expansion of haematopoietic stem and progenitor cells in cytokine combinations is effective in promoting differentiation and proliferation of multilineage progenitor cells, but often results in reduction of self‐renewable stem cells. This study investigated the effect of a mannose‐binding lectin, NTL, purified from Narcissus tazetta var. chinensis, on prolonged maintenance and expansion of cord blood CD34+ cells. Our results showed that the presence of NTL or Flt‐3 ligand (FL) significantly preserved a population of early stem/progenitor cells in a serum‐ and cytokine‐free culture for 35 d. The effect of NTL on the ex vivo expansion of CD34+ cells in the presence of stem cell factor, thrombopoietin (TPO) and FL was also investigated. NTL‐enhanced expansion of early progenitors (CD34+, CD34+CD38−, mixed colony‐forming units and CFU‐GEMM) and committed progenitor cells (granulocyte CFU, erythroid burst‐forming units/CFU and megakayocyte CFU) after 8 and 12 d of culture. Six weeks after transplanting 12 d‐expanded cells to non‐obese diabetic severe combined immunodeficient mice, increased engraftment of human CD45+ cells was observed in the bone marrow of animals that received NTL‐treated cells. The dual functions of NTL on long‐term preservation and expansion of early stem/multilineage progenitor cells could be developed for applications in various cell therapy strategies, such as the clinical expansion of CD34+ cells for transplantation.
Impacts of Argentine ants on mealybugs and their natural enemies in California’s coastal vineyards
Authors: DAANE KENT M. , SIME KAREN R. , FALLON JULIE , COOPER MONICA L.
Published: October 2007

Abstract 1. The Argentine ant, Linepithema humile, tends honeydew‐excreting homopterans and can disrupt the activity of their natural enemies. This mutualism is often cited for increases in homopteran densities; however, the ant’s impact on natural enemies may be only one of several effects of ant tending that alters insect densities. To test for the variable impacts of ants, mealybug and natural enemy densities were monitored on ant‐tended and ant‐excluded vines in two California vineyard regions.

2. Ant tending increased densities of the obscure mealybug, Pseudococcus viburni, and lowered densities of its encyrtid parasitoids Pseudaphycus flavidulus and Leptomastix epona. Differences in parasitoid recovery rates suggest that P. flavidulus was better able to forage on ant‐tended vines than L. epona.

3. Densities of a coccinellid predator, Cryptolaemus montrouzieri, were higher on ant‐tended vines, where there were more mealybugs. Together with behavioural observations, the results showed that this predator can forage in patches of ant‐tended mealybugs, and that it effectively mimics mealybugs to avoid disturbance by ants.

4. Ant tending increased densities of the grape mealybug, Pseudococcus maritimus, by increasing the number of surviving first‐instar mealybugs. Parasitoids were nearly absent from the vineyard infested with P. maritimus. Therefore, ants improved either mealybug habitat or fitness.

5. There was no difference in mealybug distribution or seasonal development patterns on ant‐tended and ant‐excluded vines, indicating that ants did not move mealybugs to better feeding locations or create a spatial refuge from natural enemies.

6. Results showed that while Argentine ants were clearly associated with increased mealybug densities, it is not a simple matter of disrupting natural enemies. Instead, ant tending includes benefits independent of the effect on natural enemies. Moreover, the effects on different natural enemy species varied, as some species thrive in the presence of ants.
Change in the distribution of a member of the strand line community: the seaweed fly (Diptera: Coelopidae)
Authors: EDWARD DOMINIC A. , BLYTH JENNIFER E. , MCKEE RODERICK , GILBURN ANDRÉ SIMON
Published: October 2007

Abstract 1. Coastal organisms are predicted to be particularly susceptible to the impact of global warming. In this study the distribution and relative abundance of two coastal invertebrates, Coelopa frigida (Fabricius) and C. pilipes are investigated.

2. Coelopa pilipes has a more southerly distribution than C. frigida, and prefers a warmer climate. Coelopa pilipes is less resistant to sub‐zero temperatures than C. frigida and its northerly distribution is probably limited by cold winter days.

3. The most recent distribution map of C. frigida and C. pilipes in northern Europe was published a decade ago and showed the northerly extent of the distribution of C. pilipes reaching the north coast of mainland Scotland but its complete absence from the Western and Northern Isles.

4. C. pilipes has now spread throughout the Western Isles and the Orkney Islands but is still absent from Shetland. There has also been an increase in the relative frequency of C. pilipes at sites harbouring coelopids on the British mainland. A similar pattern of distribution change along the west coast of Sweden is reported.

5. It is proposed that these changes have occurred primarily as a result of global warming and in particular due to the recent increase in winter temperatures. A number of other indirect effects may have also contributed to these changes, including a probable change in macroalgae distribution. The implications of these changes for the wrack bed ecosystem and at higher trophic levels are considered.
Nutrient dependent effects of consumer identity and diversity on freshwater ecosystem function
Authors: DZIALOWSKI ANDREW R. , SMITH VAL H.
Published: October 2007

1. Over the past decade, ecologists have tried to determine how changes in species composition and diversity affect ecosystem structure and function. Until recently, the majority of these studies have been conducted in terrestrial ecosystems and have not taken into account environmental variability. The purpose of this research was to determine how species identity and diversity in the freshwater zooplankton affected biomass of algae and zooplankton at two levels of nutrient enrichment.

2. Several species of cladocerans were grown alone and together in microcosms at both ambient and raised phosphorus concentrations to determine if the effects of consumer identity and diversity were nutrient dependent.

3. Total zooplankton biomass was greater, while algal biomass was lower, in mixed culture than in monoculture. The effects of zooplankton diversity on algal biomass, however, were only observed at raised phosphorus concentrations, suggesting that diversity effects were nutrient dependent. Specifically, diversity effects appeared to be related with biological mechanisms such as complementarity in resource use and/or facilitation.

4. More diverse communities of zooplankton appear to be better able to control algae than single species of zooplankton at high nutrient concentrations; therefore, zooplankton diversity may provide a buffer against eutrophication in freshwater ecosystems.
Phosphorus and light colimit periphyton growth at subsaturating irradiances
Authors: HILL WALTER R. , FANTA SHARI E.
Published: October 2007

1. This study investigated the combined effects of light and phosphorus on the growth and phosphorus content of periphyton. To investigate the potential for colimitation of algal growth by these two resources, diatom‐dominated periphyton communities in large flow‐through laboratory streams were exposed under controlled conditions to simultaneous gradients of light and phosphorus.

2. Periphyton growth rate was predictably light‐limited by the subsaturating irradiances (12–88 μmol photons m−2 s−1) used in this experiment. However, phosphorus concentration also limited growth rate: growth increased hyperbolically with increasing soluble reactive phosphorus (SRP), reaching a threshold of growth saturation between 22 and 82 μg L−1.

3. Periphyton phosphorus content was strongly and nonlinearly related with SRP, reaching a maximum at 82 μg L−1SRP. Contrary to the Light : Nutrient Hypothesis, periphyton phosphorus content did not decrease with increasing light, even at the lowest concentrations of SRP. Periphyton phosphorus was highly correlated with periphyton growth rate (Spearman'sρ = 0.63,P < 0.005).

4. Multiple regression analysis reinforced evidence of simultaneous light and phosphorus limitation. Both light and periphyton phosphorus content were significant variables in multiple regressions with growth parameters as dependent variables. Light alone accounted for 67% of the variance in periphyton biomass, and the addition of periphyton phosphorus as an additional independent variable increased the total amount of variance explained to 81%.

5. Our results did not support the hypothesis that extra phosphorus is required for photoacclimation to low light levels. Rather, the effect of additional phosphorus may have been to accommodate increased requirements for P‐rich ribosomal RNA when growth was stimulated by increased light. The potential colimitation of periphyton growth by phosphorus and light at subsaturating irradiances has important implications in both theoretical and applied aquatic ecology.
European‐wide GIS‐based modelling system for quantifying the feedstock from Miscanthus and the potential contribution to renewable energy targets
Authors: STAMPFL PAUL F. , CLIFTON‐BROWN JOHN C. , JONES MICHAEL B.
Published: October 2007

Reliable estimates of feedstock resources are a prerequisite to the establishment of a biomass based‐industry for energy and non food products. Field trials in the European Union (EU) show that Miscanthus spp. can produce high yields. Here we use a model (MISCANMOD) coupled with a GIS environment to estimate the contribution that Miscanthus could make to projected national electricity consumption. We describe the integration of different data sets, transformation procedures, and spatial analyses using GIS to produce energy statistics for the EU‐25. Overall, Miscanthus grown on the 10% of arable land which is currently in set‐aside could generate 282 TWh yr−1 electricity. This would meet 39% of the EU‐25 target of 723 TWh yr−1 of electricity from renewable energy sources (RES) by 2010. As RES targets rise, land available for energy crops is also expected to increase. We consider three additional scenarios where Miscanthus could be grown on 10%, 20% and 35% of all agricultural land and we estimate it could generate respectively 345, 691 and 1209 TWh yr−1 of electrical energy. At a national scale France, Poland and Germany have the highest potentials for Miscanthus production based on agricultural land area (respectively 83, 52, 49 TWh yr−1 when 10% agricultural land is used). Finally, we reduced the scale to the EU NUTS2 (Nomenclature of Territorial Units for Statistics) regions to examine regional generation capacities. Key regions have been identified where national RES targets are exceeded. These regions could become net exporters of renewable energy.
Predicting potential impacts of climate change on the geographical distribution of enchytraeids: a meta‐analysis approach
Authors: BRIONES MARÍA JESÚS I. , INESON PHIL , HEINEMEYER ANDREAS
Published: October 2007

The expectation that atmospheric warming will be most pronounced at higher latitudes means that Arctic and montane systems, with predominantly organic soils, will be particularly influenced by climate change. One group of soil fauna, the enchytraeids, is commonly the major soil faunal component in specific biomes, frequently exceeding above‐ground fauna in biomass terms. These organisms have a crucial role in carbon turnover in organic rich soils and seem particularly sensitive to temperature changes. In order to predict the impacts of climate change on this important group of soil organisms we reviewed data from 44 published papers using a combination of conventional statistical techniques and meta‐analysis. We focused on the effects of abiotic factors on total numbers of enchytraeids (a total of 611 observations) and, more specifically, concentrated on total numbers, vertical distribution and age groupings of the well‐studied speciesCognettia sphagnetorum(228 observations). The results highlight the importance of climatic factors, together with vegetation and soil type in determining global enchytraeid distribution; in particular, cold and wet environments with mild summers are consistently linked to greater densities of enchytraeids. Based on the upper temperature distribution limits reported in the literature, and identified from our meta‐analyses, we also examined the probable future geographical limits of enchytraeid distribution in response to predicted global temperature changes using the HadCM3 model climate output for the period between 2010 and 2100. Based on the existing data we identify that a maximum mean annual temperature threshold of 16 °C could be a critical limit for present distribution of field populations, above which their presence would decline markedly, with certain key species, such asC. sphagnetorum, being totally lost from specific regions. We discuss the potential implications for carbon turnover in these organic soils where these organisms currently dominate and, consequently, their future role as C sink/source in response to climate change.
Climate change impacts on structure and diversity of fish communities in rivers
Authors: DAUFRESNE MARTIN , BOËT PHILIPPE
Published: October 2007

It is widely accepted that climate change constrains biota. Yet, because of the lack of consistent multisite and multitaxon surveys, few studies have addressed general rules about how climate change impacts on structure and diversity of animal communities. Especially, the relative influence of nonclimatic anthropogenic disturbances on this impact is fairly unknown. Here, we present for the first time a meta‐analysis assessing the effect of global warming on stream organisms. Fish communities of large rivers in France undergoing various anthropogenic pressures showed significant increase in proportions of warm‐water species and of specific richness during the last 15–25 years. Conversely, the equitability decreased, indicating a gradual decrease of the number of dominant species. Finally, the total abundance increased, coupled with rejuvenation and changes in size‐structure of the communities. Interestingly, most of these effects were not depressed by the strength of nonclimatic anthropogenic disturbances. Conversely, geographical location of communities and especially closeness of natural barriers to migration could influence their response to climate change. Indeed, increase in the proportion of southern species seemed hindered at sites located close to the southern limit of the European species' geographical ranges. This work provides new evidence that climate change have deep impacts on communities which, by overtaking the effects of nonclimatic anthropogenic disturbances, could be more substantial than previously thought. Overall, our results stress the importance of considering climate change impacts in studies addressing community dynamics, even in disturbed sites.
Energy feedbacks of northern high‐latitude ecosystems to the climate system due to reduced snow cover during 20th century warming
Authors: EUSKIRCHEN E. S. , McGUIRE A. D. , CHAPIN F. S.
Published: October 2007

The warming associated with changes in snow cover in northern high‐latitude terrestrial regions represents an important energy feedback to the climate system. Here, we simulate snow cover‐climate feedbacks (i.e. changes in snow cover on atmospheric heating) across the Pan‐arctic over two distinct warming periods during the 20th century, 1910–1940 and 1970–2000. We offer evidence that increases in snow cover–climate feedbacks during 1970–2000 were nearly three times larger than during 1910–1940 because the recent snow‐cover change occurred in spring, when radiation load is highest, rather than in autumn. Based on linear regression analysis, we also detected a greater sensitivity of snow cover–climate feedbacks to temperature trends during the more recent time period. Pan‐arctic vegetation types differed substantially in snow cover–climate feedbacks. Those with a high seasonal contrast in albedo, such as tundra, showed much larger changes in atmospheric heating than did those with a low seasonal contrast in albedo, such as forests, even if the changes in snow‐cover duration were similar across the vegetation types. These changes in energy exchange warrant careful consideration in studies of climate change, particularly with respect to associated shifts in vegetation between forests, grasslands, and tundra.