bluuebunny/crossref_metadata_2025 huggingface dataset:
SnBversion 2.3: triplet sieve phasing for centrosymmetric structures
Authors: Xu Hongliang , Smith Alexander B. , Sahinidis Nikolaos V. , Weeks Charles M.
Published: April 2008

A new version of the direct-methods programSnBhas been developed. This version incorporates the triplet sieve method for phasing centrosymmetric structures in a way that is transparent to users. The triplet sieve procedure may decrease significantly the time required to achieve a solution for such structures.
Of crystals, structure factors and diffraction images
Authors: Jovine Luca , Morgunova Ekaterina , Ladenstein Rudolf
Published: April 2008

It is suggested that it would be useful if raw X-ray diffraction images could be included in data depositions with the Protein Data Bank.
A COHORT ANALYSIS OF US AGE–EARNINGS PROFILES
Authors: Fukuda Kosei
Published: April 2008

Aggregate data on US earnings, classified by period and by age, are decomposed into age, period and cohort effects, using the Bayesian cohort models, which were developed to overcome the identification problem in cohort analysis. The main findings, obtained by comparing college and high school graduates, are threefold. First, the age effects show a downward trend for the age group of 45–49 onwards for high school graduates but do not show any such trend for college graduates. Second, the period effects show a downward trend for high school graduates but reveal no such trend for college graduates. Third, the cohort effects are negligible for both college and high school graduates.
STRUCTURAL SHIFTS IN UK UNEMPLOYMENT 1979–2005: THE TWIN IMPACTS OF FINANCIAL DEREGULATION AND COMPUTERIZATION
Authors: Baddeley Michelle C.
Published: April 2008

This paper analyses UK unemployment in the period 1979–2005. Structural breaks are identified endogenously and they coincide with key institutional changes associated with financial deregulation and computerization in the New Economy. A vector error correction model is estimated and it confirms that computerization and financial deregulation have had counteracting impacts on UK unemployment. The results are consistent with three hypotheses: technological advances associated with computerization have moderated inflationary struggles between firms and insiders by increasing total factor productivity; financial deregulation has generated financial fragility fostering rises in unemployment; financial deregulation and computerization together have been associated with shifts from manufacturing towards services, fostering structural unemployment.
Size at maturity of Atlantoraja platana (Günther, 1880) (Chondrichthyes: Rajidae: Arhynchobatinae) in the south‐west Atlantic Ocean
Authors: Oddone M. C. , Amorim A. F.
Published: April 2008

The sexual development of Atlantoraja platana from the south‐west Atlantic Ocean was analysed. According to the reproductive variables considered for both sexes, males were found to mature at 620 mm and females at 715 mm total length.
Winter diet and condition of two 0+ year cyprinid fish species in the lower River Trent, England
Authors: Nunn A. D. , Harvey J. P. , Cowx I. G.
Published: April 2008

The winter diets of 0+ year juvenile daceLeuciscus leuciscusand roachRutilus rutilusin the lower River Trent, England, were dominated by aufwuchs. There were no significant changes in the relative condition of either fish species over the winter.
Parasites of the Brazilian sandperch Pinguipes brasilianus Cuvier: a tool for stock discrimination in the Argentine Sea
Authors: Timi J. T. , Lanfranchi A. L. , Etchegoin J. A. , Cremonte F.
Published: April 2008

The use of parasites as biological tags allowed the identification of three stocks of Brazilian sandperch Pinguipes brasilianus in the Argentine Sea. A total of 156 specimens caught during spring 2006, off the coasts of Buenos Aires Province (38°27′ S; 57°90′ W, n = 54), San Matías Gulf (42° S; 65°10′ W, n = 52) and Nuevo Gulf (42°09′ S; 64°05′ W, n = 50), were examined for parasites and 21 species were found, including monogeneans, digeneans, cestodes, nematodes, acanthocephalans and crustaceans. Diet analyses showed that Brazilian sandperch feed mainly on benthic macroinvertebrates, with differences in relative importance of main items between zones. Univariate analysis on parasite population descriptors, as well as a discriminant analysis, allowed the identification of discrete stocks in each zone, although a higher degree of similarity was observed between both Patagonian Gulfs. Northern samples were characterized by higher values of prevalence and abundance of Grillotia sp., Corynosoma australe and Scolex polymorphus. On the other hand, Trifur tortuosus and Opecoelidae gen. sp. were important in determining the position of Patagonian samples and were specially related to those from Nuevo Gulf, whereas none of the species was clearly related only to fish from San Matías Gulf. The size of the hosts is likely to influence the similarity among zones, with larger fish as better tools to discriminate stocks, probably because they harbour ‘mature’ assemblages shaped longer by differential environmental conditions and diet in each zone. Parasite species characteristic of sandperch from Buenos Aires Province, which display very low specificity among fish species in this area, have been previously identified as biological tags for other host species in these region, confirming their value as tags for stock delineation.
Interspecific differences of parental polychlorinated biphenyl exposure on nutrient availability, egg production and brooding in two Syngnathus species
Authors: Ripley J. L. , Foran C. M.
Published: April 2008

Parental nutrient contribution of two closely related, sympatric pipefish species was investigated following exposure to mid‐range environmental concentrations of the polychlorinated biphenyl (PCB) mixture Aroclor 1254 (mean ±s.e. = 52·89 ± 2·12 μg l−1). This study tested the hypothesis that differential nutrient supplementation during development predicts interspecific sensitivity to environmental stressors. Specifically, paternal PCB exposure was predicted to affect Syngnathus fuscus development because embryos depend on paternally derived nutrient sources in the brood pouch. Conversely, changes in Syngnathus floridae egg production were expected following maternal PCB treatment as a nurse‐egg system generates the nutrient‐rich pouch fluid. Lipid concentrations in adult blood plasma were significantly elevated following Aroclor 1254 treatment in S. floridae gravid females and post‐brooding S. fuscus males (P < 0·001) which suggested mobilization from body tissues in response to metabolic demands. Aroclor 1254 treatment also resulted in decreased protein concentrations in S. fuscus pouch fluid (P < 0·05). These changes were not translated into significant exposure‐related effects in the nutrient reserves of eggs and fry or fry size. Overall S. fuscus demonstrated a general sensitivity to disturbances from laboratory exposure conditions. Whereas a previous investigation of field‐collected pipefishes showed comparable interspecific pouch fluid and fry nutrient concentrations and egg size, here, nutrient levels and egg diameter decreased in both laboratory‐mated control and PCB‐exposed S. fuscus. This study demonstrates the potential physiological effects of PCB exposure on parental nutrient allocation in syngnathids and the general sensitivity of S. fuscus to environmental disturbances.
Rapid learning of shelter position in an intertidal fish, the shannyLipophrys pholisL.
Authors: Burt de Perera T. , Guilford T. C.
Published: April 2008

The homing ability of an intertidal fish, the shannyLipophrys pholis, was investigated using two experiments that were based on the shanny’s natural propensity to home to a refuge. A displacement experiment demonstrated that the fish were able to accurately locate the previous position of a refuge once the shelter itself had been removed so that it could not be used as a cue to directly signal the goal location. This shows that the shanny can encode information about its familiar surroundings into a spatial map and use this information to home. A second experiment in which the cues internal and external to the experimental tank were put in conflict with one another suggested that the shanny can encode cues that are both intra‐ and external‐tank cues in its representation of space, but that there is individual variation in the type of cues that are used, or memorized.
Scarring patterns and relative mortality rates of Indian Ocean whale sharks
Authors: Speed C. W. , Meekan M. G. , Rowat D. , Pierce S. J. , Marshall A. D. , Bradshaw C. J. A.
Published: April 2008

This study recorded the scarring rate and severity for whale sharks Rhincodon typus from three Indian Ocean aggregations (Australia, Seychelles and Mozambique), and examined whether scarring (mostly attributed to boat strikes and predator attacks) influences apparent survival rates using photo‐identification libraries. Identifications were based on spot‐and‐stripe patterns that are unique to individual whale sharks. Scarring was most prevalent in the Seychelles aggregation (67% of individuals). Predator bites were the most frequent source of scarring (aside from minor nicks and abrasions) and 27% of individuals had scars consistent with predator attacks. A similar proportion of whale sharks had blunt trauma, laceration and amputation scars, the majority of which appeared to be caused by ship collisions. Predator bites were more common (44% of individuals) and scars from ship collisions were less common at Ningaloo Reef than at the other two locations (probability of among‐site differences occurring randomly = 0·0007 based on a randomized multinomial contingency analysis). In all aggregations, scars occurred most often on the caudal fin, which may result from the fin being the body part closest to the surface when boats pass over, or they may provide a large target for predator attack. No evidence was found for an effect of scarring on apparent survival (φ; mean ±s.e.) for the Ningaloo (not scarred φ= 0·858 ± 0·033; scarred φ= 0·929 ± 0·033) or Seychelles populations (not scarred φ= 0·502 ± 0·060; scarred φ= 0·538 ± 0·070). The lower apparent survival of the Seychelles population may be attributed to a high number of transient whale sharks in this aggregation that might bias estimates. This study indicates that while scarring from natural predators and smaller vessels appears to be unrelated to whale shark survival, the effect of deaths related to ship strike need to be quantified to assist in future management of this species.
Effects of ambient colour on colour preference and growth of juvenile rainbow trout Oncorhynchus mykiss (Walbaum)
Authors: Luchiari A. C. , Pirhonen J.
Published: April 2008

Colour preference of individual juvenile rainbow trout Oncorhynchus mykiss was tested at 1 and 12° C, and also at 12° C after a 42 day growth experiment under white, blue, green, yellow or red ambient colour. All experiments were carried out under controlled laboratory conditions and the preference was assessed by the location of the fish in a preference tank with four chambers. Rainbow trout showed a preference for blue and green at 1° C and for green at 12° C. After the growth experiment the fish reared in blue tanks preferred blue and green but green was the most preferred colour for the fish reared in green, yellow and red tanks. Yellow and especially red chambers were avoided, irrespective of the ambient colour during the growth trial. The final mass of fish reared in the red aquaria was significantly smaller than that of the fish in green tanks. In addition, when the data of the preference tests were correlated with the data of the growth experiment using mean values of the four tested colours, a very good linear relationship was observed between the preference (i.e. visit frequency in coloured compartments) and growth rate as well as food intake. When considering the results both from the preference and growth trials it is suggested that green is the best environmental colour for rearing juvenile rainbow trout while rearing in a red environment cannot be recommended.
Value‐added education and smoking uptake in schools: a cohort study
Authors: Markham Wolfgang A. , Aveyard Paul , Bisset Sherri L. , Lancashire Emma R. , Bridle Christopher , Deakin Sara
Published: April 2008

Aim  To show that schools achieving higher examination pass and lower truancy rates than expected, given that their pupil populations (high value‐added schools) are associated with a lower incidence of smoking among pupils (13–14 years).

Design  Value‐added scores for schools were derived from standardized residuals of two regression equations predicting separately the proportion of pupils passing high school diplomas and the half‐days lost to truancy from the socio‐economic and ethnic profiles of pupils. The risk of regular smoking at 1‐ and 2‐year follow‐up was examined in relation to the value‐added score in a cohort of 8352 UK pupils. Random‐effects logistic regression was used to adjust for baseline smoking status and other adolescent smoking risk factors.

Setting  A total of 52 schools, West Midlands, UK.

Participants  Year 9 pupils aged 13–14 years (n = 8352) were followed‐up after 1 year (n = 7444; 89.1% of original cohort) and 2 years (n = 6819; 84.6% of original cohort excluding pupils from two schools that dropped out).

Measurements  Regular smoking (at least one cigarette per week).

Findings  Schools with high value‐added scores occurred throughout the socio‐demographic spectrum. The odds ratio (95% confidence interval) for regular smoking for a 1 standard deviation increase in the value‐added measure was 0.85 (0.73–0.99) at 1‐year and 0.80 (0.71–0.91) at 2‐year follow‐ups. Baseline smoking status did not moderate this.

Conclusions  Schools with high value‐added scores are associated with lower incidence of smoking. Some schools appear to break the strong link between deprivation and smoking. Understanding the mechanisms could be of great public health significance.
Rural–urban migration, illicit drug use and hazardous/harmful drinking in the young Thai population
Authors: Jirapramukpitak Tawanchai , Prince Martin , Harpham Trudy
Published: April 2008

Aims  Limited data are available about whether rural–urban migration, often characterized by exposure to urban life stress and a reduction in social network and support, can affect the prevalence of illicit drug use and hazardous/harmful drinking. The purpose of our study was to examine the prevalence of these risky behaviours among Thai young adults and to describe their association between their migration status and these outcomes.

Design  A population‐based cross‐sectional survey.

Setting  A representative sample of 1052 residents, aged 16–25 years (467 males and 585 females) in a suburban community of Bangkok in 2003 and 2004.

Measurements  (i) Exposures—migration (defined as the occasion when a young person born in a more rural area moves for the first time into Greater Bangkok); and (ii) outcomes—illicit drug use was assessed with an anonymous self‐report adapted from the Diagnostic Interview Schedule (DIS) and hazardous/harmful drinking with Alcohol Use Disorder Identification Test (AUDIT).

Findings  The results showed that 10.9% (82 males and 17 females) had illicit drug use and 24.3% (179 males and 62 females) hazardous and harmful drinking. In multivariate analysis, rural–urban migration was not associated with illicit drug use, whereas hazardous/harmful drinking was associated independently with being late migrants, who moved at the age of 15 or older.

Conclusions  Illicit drug use and hazardous/harmful drinking were common among young Thais. The potential effect of migration on hazardous and harmful drinking identified in this study may be helpful for the design and implementation of preventive measures.
Management of tree diversity in agricultural landscapes around Mabira Forest Reserve, Uganda
Authors: Boffa J.‐M. , Kindt R. , Katumba B. , Jourget J.‐G. , Turyomurugyendo L.
Published: April 2008

As natural forests contract, farming systems become increasingly important to landscape biodiversity conservation, yet assets and limits of their contribution are insufficiently documented. A sound understanding of farmer strategies in the management of on‐farm tree biodiversity is also critical to landscape approaches for biodiversity conservation and livelihood improvement. Diversity and management of woody species were surveyed in 105 farms around Mabira Forest in South‐Central Uganda. Farms were selected according to distance to forest, landscape axis, gender, wealth, and specialized forest use of household heads. Farmer management has a strong influence on tree diversity in the coffee–banana systems around Mabira Forest. This is reflected in the relatively high number of planted and exotic species at the levels of farm niche, farm and landscape. Both the number of years under cultivation and farmer involvement in specialized forest use were conducive to higher species diversity. Gender, wealth and tenure status did not influence tree diversity. Variation in on‐farm species richness was noted between landscape axes radiating out of the forest rather than concentric distance categories. Farming systems around Mabira Forest Reserve provide a key complementary rather than substitute tree diversity refuge and can be managed to enhance overall landscape biodiversity.
Diversity of Genus Ficus L. (Moraceae) in farmlands and pastoral areas in Buganda region, central Uganda
Authors: Ipulet Perpetua , Kasenene John
Published: April 2008

Ficus species are found in all tropical habitats occurring as epiphytes or terrestrials, and dominate agricultural ecosystems as shade trees or live fencing. Ecologically, they are indicators of ground water and keystone species providing fruit for frugivores. Their pollination is highly specialized, the pollinating wasps having co‐evolved with the host Ficus species. The study was conducted in Buganda where some species are integrated in the coffee/banana agriculture as shade trees, and a source of bark cloth or ‘olubugo’, a cultural Baganda cloth. Nine districts were surveyed covering fourteen forest and five savannah reserves, 22 farmlands and pastoral areas. Methods used were transect/quadrat, belt transects, total counts and opportunistic sampling. Altogether 32 out of the 44 species known from Uganda were recorded. The majority were epiphytic forest species, six obligate epiphytes were absent in cultivation where the most terrestrial species were recorded. Epiphytes showed no host preference, but grew on the largest or most common trees. Mean densities were the highest in drier forests and wetter savanna/cultivation and species richness indices followed the rainfall gradient. Only some forests had fairly stable populations. Species present in cultivation were sometimes absent in adjacent vegetation, and all those that survived in cultivation and savanna had known uses.
Domestication: an indigenous method in conserving plant diversity on farmlands in west Usambara Mountains, Tanzania
Authors: Msuya Tuli S. , Mndolwa Mathew A. , Kapinga Consolatha
Published: April 2008

The role of domestication in conserving indigenous plant diversity on farmlands was studied in West Usambara Mountains, Tanzania by structured, semi‐structured and unstructured interviews; participant observation; literature review and botanical identification in March 2006. There was high diversity of indigenous plant species on farmlands (73%) compared with exotics (27%). For the number of plants per species, a small proportion of indigenous plants (14%) were recorded compared with exotics (86%). Although the number of domesticated indigenous plant species has declined by 8% between 1998 and 2006, still 96% of the respondents practise domestication and they have domesticated at least one indigenous plant species each. Gender equity in domestication is lacking given that male‐headed households had domesticated significantly more plant species on farms than female‐headed households. Sustainability in domestication is questionable because of increasing number of exotic plants of very few species on farmlands, the phenomenon that encourages monoculture, thus threatening conservation of species diversity in inhabited areas. Suggestions for promoting domestication as an important indigenous method for conserving biodiversity are given, including the need for more number of studies to explore the biodiversity of other organisms associated with the domesticated indigenous plants.
Conservation of forage resources for increasing livestock production in traditional forage reserves in Tanzania
Authors: Mwilawa A. J. , Komwihangilo D. M. , Kusekwa M. L.
Published: April 2008

Traditional reserved pastures namely ‘Olopololi/Alalili’ for Maasai, ‘Ngitili’ for Sukuma and ‘Milaga’ for Gogo have been in use among the pastoral and agropastoral communities for many years. These reserves provide dry season feed for ruminant livestock especially cattle, sheep and goats. Apart from the provision of forage materials, these reserves provide fuel wood, construction material and medicinal plants. These traditional forage conservation practices also contribute to soil conservation and forage species biodiversity. However, studies conducted in these traditional forage reserves at Tingatinga (Maasai), Makang’wa (Gogo) and in Mwamishali/Mwanyanhina (Sukuma) in Tanzania show limitations of the reserves especially, in providing adequate dry matter and proteins for both maintenance and production of livestock. Nevertheless, there are opportunities for improvement on these traditional practices through introduction of improved grasses, legumes and tree/shrub species as well as proper maintenance of the superior local species and cultivars.
Species communities and associations formed by the family Cyperaceae Juss. in some of Uganda’s wetlands
Authors: Ssegawa Paul , Kalema James
Published: April 2008

This study was conducted between August 2000 and April 2001 in ten wetlands areas of Uganda and these included Lakes Bisina, Nakuwa and Opeta, including the Doho Rice Scheme in the Lake Kyoga basin; Mabamba and Lutembe bays, Lake Nabugabo, Musambwa islands and Lutoboka peninsula in the Lake Victoria basin; and Nyamuriro swamp in Kigezi region. This study focused on Cyperaceae because of their known abundance in wet or damp areas. The aim was to assess the diversity and examine the communities and associations formed by sedges. Floristic data were collected using quadrats along transects. Cluster analysis was used to analyse for species associations. Principal components analysis was used to determine the descriptive species of the sites of the wetlands. A total of 113 taxa in 107 species belonging to 17 genera and classified into seven tribes were identified. The most rare species included Eleocharis dulcis (Burm. f.) Henschel and Cyperus iria L. Using cluster analysis the ten sites of the wetlands were classified into sedge assemblages that generally reflected ecoregional differences between the Lake Kyoga and Victoria basins. The three distinct clusters formed from cluster analysis also revealed species assemblages that represented associations of these sedges found in the sites of each cluster.
Untangling the complex issue of dissolved organic carbon uptake: a stable isotope approach
Authors: KAPLAN LOUIS A. , WIEGNER TRACY N. , NEWBOLD J. D. , OSTROM PEGGY H. , GANDHI HASAND
Published: April 2008

1. We estimated uptake of stream water dissolved organic carbon (DOC) through a whole‐stream addition of a 13C‐DOC tracer coupled with laboratory measurements of bioavailability of the tracer and stream water DOC.

2. The tracer, a leachate of 13C‐labelled tree tissues, was added to the head waters of White Clay Creek, Pennsylvania, U.S.A., over a 2‐h period and followed 1.27 km downstream to generate mass transfer coefficients for DOC lability classes within the tracer.

3. From the longitudinal 13C uptake curve, we resolved labile and semi‐labile DOC classes within the 13C‐DOC tracer comprising 82% and 18% of the tracer respectively.

4. Plug‐flow laboratory bioreactors colonized and maintained with stream water were used to determine the concentration of stream water DOC fractions that had a similar lability to the labile and semi‐labile classes within the tracer and we assumed that stream water DOC and tracer DOC with comparable lability fractions in the bioreactors behaved similarly in the stream, i.e. they had the same mass transfer coefficients.

5. A small fraction (8.6%) of the stream water DOC was labile, travelling 238 m downstream before being taken up. The remaining bioavailable stream water DOC was semi‐labile and transported 4.5 km downstream before being taken up. These uptake lengths suggest that the labile DOC is an energy source within a stream reach, while the semi‐labile DOC is exported out of the reach to larger rivers and the downstream estuary, where it may provide energy for marine microbial communities or simply be exported to the oceans.
Size‐independent age effects on reproductive effort in a small, short‐lived fish
Authors: TEDESCO PABLO A. , BENITO JOSEP , GARCÍA‐BERTHOU EMILI
Published: April 2008

1. Age‐related changes in reproductive effort have been predicted by theoretical models and observed in a wide range of organisms. However, for indeterminate growers such as fish, an allometric relationship linking gonad weight to body size is commonly observed. There is often a positive linear relationship when these variables are log‐transformed, which by implication reduces the influence of age on reproductive effort.

2. Contrasting with this usual pattern, we report a nonlinear relationship between gonad weight and fish size (after log‐transformation) in mosquitofish (Gambusia holbrooki), clearly resulting from age changes. The declining rate of increase of gonad mass as a function of body size revealed a higher reproductive effort for younger individuals relative to size.

3. This size‐independent age effect on reproductive effort was predicted based on previous studies of mosquitofish and is certainly related to their particular life‐history strategy, combining an early maturation and short lifespan with the physiological costs of reproduction and over‐wintering. Our findings probably apply to other small, short‐lived species with similar life history.
Echo‐sounding can discriminate between fish and macroinvertebrates in fresh water
Authors: JURVELIUS JUHA , KNUDSEN FRANK REIER , BALK HELGE , MARJOMÄKI TIMO J. , PELTONEN HEIKKI , TASKINEN JOUNI , TUOMAALA ANTTI , VILJANEN MARKKU
Published: April 2008

1. Acoustic scattering from fish and macroinvertebrates was studied in a boreal Finnish lake at three echosounder frequencies (38, 120 and 200 kHz). Split‐beam transducers with partly overlapping 7° beams were employed. Acoustic, fish and invertebrate sampling were undertaken simultaneously. Vertical gradients of temperature and oxygen concentration were measured during the exercise.

2. At all frequencies, a narrow scattering layer coincided with the thermocline. At 38 kHz, fish were detected well with practically no reverberation from invertebrates while 200 kHz detected both fish and invertebrates.

3. Minor differences in the magnitude of acoustic scattering from fish were found between frequencies and between depth layers, but scattering at different frequencies was correlated at all depths. Acoustic scattering and fish density indices from trawl catches, consisting mostly of smelt (Osmerus eperlanus) (97%) and vendace (Coregonus albula) (3%), were significantly correlated.

4. Acoustic scattering from invertebrates increased with sound frequency. Correlation analysis suggested that the invertebrate scattering was mostly induced by Chaoborus flavicans. A low frequency is recommended for estimating fish abundance without bias from reverberation induced by invertebrate scattering. Although fish and invertebrates can also be successfully discriminated at a single frequency by thresholding and cross filtering, the combination of a low and a high frequency is a more robust tool for effective fish‐invertebrate discrimination.
Food quality influences habitat selection in Daphnia
Authors: REICHWALDT ELKE S.
Published: April 2008

1. The vertical distribution of Daphnia in stratified lakes strongly depends on the depth profiles of temperature and food resources. However, ecological requirements for these factors are slightly different for juvenile and adult Daphnia.

2. Here, I investigated whether food quality influences the habitat selection of Daphnia pulicaria at night and whether the habitat selection of juvenile and adult D. pulicaria is different. Daphnia were allowed to choose their optimal habitat in large, stratified water columns (plankton towers, Plön) that held either the green alga Scenedesmus obliquus (high quality) in the cold hypolimnion (Hypo‐treatment) or S. obliquus in the warm epi‐ and cold hypolimnion (SCEN‐treatment) or the non‐toxic cyanobacterium Synechococcus elongatus (low quality) in the warm epilimnion and S. obliquus in the cold hypolimnion (SYN treatment).

3. When food (S. obliquus) was present only in the hypolimnion (Hypo‐treatment), juveniles and adults distributed similarly in the water column and spent most of their time in the interface between the warm and the food rich layer.

4. When food was present in the epilimnion and hypolimnion (SCEN‐ and SYN‐treatments), juvenile and adult D. pulicaria moved into the warm and now also food‐rich epilimnion, however, the magnitude of this shift depended on the food type and age class of Daphnia. Adult and juvenile D. pulicaria spent most of their time in the epilimnion when food there was of a high quality (S. obliquus; SCEN‐treatment). However, compared to the juveniles, adult Daphnia spent significantly more time in the colder hypolimnion when epilimnetic food was of a low quality (S. elongatus; SYN‐treament).

5. Therefore, habitat selection of adult D. pulicaria was affected by food quality whereas the habitat selection of juveniles was not.

6. Additional growth and reproduction experiments show that the food quality is likely to be responsible for the different habitat selection of juveniles and adults in the SYN‐treatment.

7. In conclusion, my experiments show that D. pulicaria behaviourally reacts to the quality of its food source.
Population structure in the highly fragmented range of Tor douronensis (Cyprinidae) in Sarawak, Malaysia revealed by microsatellite DNA markers
Authors: NGUYEN THUY T. T.
Published: April 2008

1. Understanding the structure of threatened populations, particularly those that exist in degraded or fragmented habitats is crucial for their effective management and conservation. Recently developed methods of individual‐based analysis of genetic data provide an unprecedented opportunity to understand the relationships amongst fragmented populations.

2. In the present study, population structure of an important cyprinid species (Tor douronensis), which is indigenous to Sarawak, Malaysia, is investigated as part of an ongoing conservation effort to restore threatened wild populations of the species. The population structure inferred using data from seven autosomal microsatellite loci was generally consistent with geography and habitat fragmentation.

3. The results indicate that there are two well‐defined clusters of T. douronensis in Sarawak, namely the ‘northeastern’ and the ‘southwestern’ clusters. In addition, a further subdivision was observed in each of the clusters distributed between river systems. Low levels of gene flow were also observed and migrants between habitat fragments were identified, possibly resulting from human‐mediated translocations.

4. Implications of the findings for management and conservation of T. douronensis are discussed.
Efficacy of algal metrics for assessing nutrient and organic enrichment in flowing waters
Authors: PORTER STEPHEN D. , MUELLER DAVID K. , SPAHR NORMAN E. , MUNN MARK D. , DUBROVSKY NEIL M.
Published: April 2008

1. Algal‐community metrics were calculated for periphyton samples collected from 976 streams and rivers by the U.S. Geological Survey’s National Water‐Quality Assessment (NAWQA) Programme during 1993–2001 to evaluate national and regional relations with water chemistry and to compare whether algal‐metric values differ significantly among undeveloped and developed land‐use classifications.

2. Algal metrics with significant positive correlations with nutrient concentrations included indicators of trophic condition, organic enrichment, salinity, motility and taxa richness. The relative abundance of nitrogen‐fixing algae was negatively correlated with nitrogen concentrations, and the abundance of diatom species associated with high dissolved oxygen concentrations was negatively correlated with both nitrogen and phosphorus concentrations. Median algal‐metric values and nutrient concentrations were significantly lower at undeveloped sites than those draining agricultural or urban catchments.

3. Total algal biovolume did not differ significantly among major river catchments or land‐use classifications, and was only weakly correlated with nitrate (positive) and suspended‐sediment (negative) concentrations. Estimates of periphyton chlorophyll a indicated an oligotrophic–mesotrophic boundary of about 21 mg m−2 and a mesotrophic–eutrophic boundary of about 55 mg m−2 based on upper and lower quartiles of the biovolume data distribution.

4. Although algal species tolerance to nutrient and organic enrichment is well documented, additional taxonomic and autecological research on sensitive, endemic algal species would further enhance water‐quality assessments.
Horizontal/oblique root fractures in the palatal root of maxillary molars with associated periodontal destruction: case reports
Authors: Lin C. C. , Tsai Y. L. , Li U. M. , Chang Y. C. , Lin C. P. , Jeng J. H.
Published: April 2008

Aim  To report two cases of palatal root fracture in maxillary molars that were successfully managed in the short term by root canal treatment and root amputation.

Summary  In the first case, a 48‐year‐old woman with bony destruction and a deep periodontal pocket on the palatal root of tooth 26 (FDI) underwent root canal treatment. Bleeding into the palatal canal and radiolucent lines over the root suggested a fracture. Further evidence was provided by an electronic apex locator. Subsequent surgery confirmed the presence of a horizontal root fracture and the fractured root was removed. In the second case, a 75‐year‐old woman presented with pain from the left posterior teeth. Clinical examination revealed an oblique root fracture of tooth 27 palatal roots with abscess formation and a deep periodontal pocket. Palatal root amputation and odontoplasty were performed. This was followed by root canal treatment. Both teeth were preserved in the short term and early healing of these two cases was uneventful.

Key learning points 

Horizontal/oblique root fracture of the palatal root in molars is rare.

A combination of periodontal and root canal treatment and palatal root amputation may allow short‐term preservation of functional teeth.
Preparation and evaluation of pizza cheese made from blend of vetch–bovine milk
Authors: Salim‐ur‐Rehman  , Piggott John R. , Ahmad Muhammad Mushtaq , Hussain Sarfraz , Ahmad Nasir , Owusu‐Darko Patricia
Published: April 2008

The objective of the study was to develop vetch–bovine milk (VBM) pizza cheese low in animal fat and its acceptability was determined through physico‐chemical, functional and sensory evaluations. Vetch (Lathyrus sativus) was detoxified by steeping in double its quantity of water for 8 h at 70 °C, changing the water seven times, draining and sun drying. Dried vetch was then treated with water at pH 4.0 at 90 °C for 60 min to deplete the beany flavour, then dried and milled into fine flour with Quadrumate Senior mill. The seed coat was separated as one of the mill fractions. Four types of VBM blends were prepared from vetch flour and bovine skimmed milk powder and were used to prepare cheese using 2.5% lactic acid bacterial culture of Streptococcus thermophillus and Streptococcus bulgaricus and rennet (0.15 mL L−1, 1:40 ratio with water). The cheese was stored at 4 °C for 14 days and used as topping over the pizza shell. Physico‐chemical analyses, such as moisture, total solids, lactose, ash, fat, titratable acidity and pH, and sensory evaluations of both cheese and pizza were carried out at 0‐, 7‐ and 14‐day intervals. The stretchability and meltability of cheese increased significantly (P < 0.05) during storage. Commercial Mozzarella cheese was taken as a control. The results of this study suggested that VBM blend at the ratio of 12.5:87.5 (vetch flour:bovine milk powder) could be utilised to prepare a cheese of desirable characteristics for pizza topping.
Effect of pH and addition of corn oil on the properties of whey protein isolate‐based films using response surface methodology
Authors: Wang Lizhe , Liu Li , Holmes Justin , Huang Jian , Kerry John F. , Kerry Joe P.
Published: April 2008

Response surface methodology (RSM) was used to investigate pH and corn oil (CO) effects on the properties of films formed from whey protein isolate (WPI). Test films were evaluated for tensile strength (TS), puncture strength (PT), percentage elongation at break point (E), water vapour permeability (WVP) and oxygen permeability (OP). TS of WPI films increased with increasing pH, while addition of CO produced no trend. However, when WPI solution pH increased >10.0, film TS generally decreased with CO addition (>11%). E values increased dramatically with increasing levels of CO when pH for WPI solutions were >8.5. However, pH had no effect on E values. WPI solutions possessing high pH values (maximum pH value of 10.62) produced WPI films with the highest PT values. WVP had a quadratic relationship with pH and CO addition. OP had an inversely linear relationship with increasing pH (6.5–10.5) and a quadratic relationship with CO addition. Optimal pH (9.88) and CO level (2.93%), determined from physical test film data, were predicted by RSM.
Carbohydrate‐based fat replacers in the modification of the rheological, textural and sensory quality of yoghurt: comparative study of the utilisation of barley beta‐glucan, guar gum and inulin
Authors: Brennan Charles S. , Tudorica Carmen M.
Published: April 2008

Barley beta‐glucan, partially hydrolysed guar gum and inulin were used in the processing of low‐fat yoghurts. The possible beneficial effects of carbohydrate fat replacers on the rheological, textural and sensory quality of low‐fat yoghurt‐based products were determined. Comparisons were made between the sample yoghurts made from a low‐fat milk base, and full‐fat and low‐fat yoghurt controls. The inclusion of the carbohydrate components reduced product syneresis and improved the texture and rheological properties of the low‐fat‐based products so that their quality characteristics were similar to yoghurt made with full‐fat milk. Both the type and also the amount of carbohydrate component altered product characteristics. Beta‐glucan addition at low level (0.5%) was effective in improving serum retention of the yoghurt and its viscoelastic nature (G′, G′ and tan δ). In contrast, higher levels (above 2%) of inulin and guar gum were needed to exert significant improvements in the textural characteristics of yoghurt. Sensory analysis conducted on the samples illustrated that the inclusion of carbohydrate‐based fat replacers could be successfully utilised to mimic full‐fat products.
Moisture sorption isotherm and xerophilic moulds associated with dried cocoyam chips in storage in Nigeria
Authors: Ugwuanyi J. Obeta
Published: April 2008

Extended storage of cocoyams (Colocasia antiquorum and Colocasia esculenta) is achieved in parts of Nigeria by processing them into smoked and dried chips. In this study, cocoyam chips were collected from parts of Nigeria at the end of drying, at various periods of storage and from markets, and analysed for moisture content, moisture sorption characteristics and xerophilic moulds. Moisture content of chips ranged from 7.07 ± 1.1% for freshly dried samples to 16 ± 2.2% for samples stored up to 8 months. Six mould species from four groups of the genus Aspergillus (including five xerophiles) identified as Aspergillus fumigatus, Eurotium repens, Eurotium amstelodami, Eurotium chevalieri and Aspergillus flavus and Aspergillus niger and Mucor sp. were isolated. The variety of moulds increased with storage and moisture content of samples. Moisture sorption in dried chips showed type II sigmoidal behaviour. Wood smoke significantly protected chips from mould colonization, but in cooperation with reduced water activity. Simple and inexpensive storage of freshly dried samples in airtight bags led to prolonged storage of up to 14 months without deterioration.
Effects of differences in diet and seasonal changes on the fatty acid composition in fillets from farmed and wild sea bream (Sparus aurata L.) and sea bass (Dicentrarchus labrax L.)
Authors: Yildiz Mustafa , Şener Erdal , Timur Metin
Published: April 2008

The effects of dietary fatty acids and seasonal variation on the fatty acid profiles of farmed and wild sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) were determined by analysis of their fillets. Farmed sea bream and sea bass were fed on the same commercial feeds all year. Fatty acid profiles in the fillets reflected the fatty acid profiles of the commercial feeds. The predominant fatty acids in the trial feeds, fillets of farmed and wild sea bream and sea bass were 16:0, 18:1n‐9, 18:2n‐6, 20:5n‐3 and 22:6n‐3. The fatty acid profiles in the fillets of farmed sea bream and sea bass did not differ (P > 0.05) except in the winter season compared with those of their wild counterparts. However, the content of eicosapentaenoic acid (20:5n‐3), docosahexaenoic acid (22:6n‐3) in the fillets of the farmed and wild sea bass were significantly (P < 0.05) higher than the farmed and wild sea bream. The wild sea bream had significantly (P < 0.05) higher total saturated fatty acid and monounsaturated fatty acid (MUFA) levels, and lower total n‐6 and n‐3 polyunsaturated fatty acid (PUFA) levels in winter than in the summer and spring seasons. Similarly, in the fillets of wild sea bass, total n‐3 PUFA levels were significantly (P < 0.05) lower, and the MUFA levels were higher in winter than in the other seasons. These results indicate that the farmed fish fillets were good sources of n‐3 PUFA in each of the three seasons. However, wild fish were good sources of n‐3 PUFA in the spring and summer.
Effects of blanching, drying and extraction processes on the antioxidant activity of yam (Dioscorea alata)
Authors: Chung Yun‐Chin , Chiang Been‐Huang , Wei Ji‐Hung , Wang Chien‐Kuo , Chen Pei‐Chun , Hsu Cheng‐Kuang
Published: April 2008

The effects of blanching, drying and extraction processes on the antioxidant activities of one kind of Taiwanese yam peel, Darsan (Dioscorea alata), were investigated. The antioxidant measurements included total phenolic content, reducing power and α ,α‐diphenyl‐β‐pricryl‐hydrazyl (DPPH) radical‐scavenging activity. The 50% ethanolic, hot water and water extracts from the peel all had much higher antioxidant activities than those extracts from the flesh. Among three extraction methods, 50% ethanolic extraction resulted in the highest antioxidant activities in the peel, while hot water extraction was more appropriate for the flesh. Blanching by immersing the peel in 85 °C water for 30 s caused significant reductions in the antioxidant activities of all the extracts from the peel. Generally speaking, freeze‐dried peel maintained higher antioxidant activities than hot air‐dried peel.
Antioxidant properties of methanolic extracts from different parts of Sclerocarya birrea
Authors: Mariod Abdalbasit A. , Matthäus Bertrand , Hussein Ismail H.
Published: April 2008

The methanolic extracts from Sclerocarya birrea leaves (SCL), roots (SCR), barks (SCB), and kernel oil cake (SCK) were examined for radical scavenging capacities and antioxidant activities. The total phenolics of the extracts was determined spectrophotometrically according to the Folin‐Ciocalteau method using gallic acid as standard solution. The total phenolic compounds were found as 304.5, 367.5, 593, 148.0 and 258.0 mg g‐1 of dry product, respectively. The extracts of SCL, SCR, SCB and SCK were markedly effective in inhibiting the oxidation of linoleic acid and subsequent bleaching of β‐carotene in comparison with the control. Based on oxidation of β‐carotene/linoleic acid, the SCK extract is the most effective followed by SCR, SCL and SCB extract. The antioxidant activity determined by the DPPH (1,1‐diphenyl‐β‐picrylhydrazyl) method revealed that the SCK extract had the highest antioxidant activity on DPPH free radicals followed by SCB, SCR and SCL extracts. The effect of different extracts on the oxidative stability of sunflower oil at 70 °C was tested in the dark and compared with BHA. The oil peroxide values (PVs) were generally lower with the addition of extract in comparison to a control.
A novel method for the determination of sodium chloride in salted fish
Authors: Zhang Yinliang , Xia Wenshui
Published: April 2008

A novel, simple and reliable spectrophotometric method to determine sodium chloride in salted fish was developed and validated. The method was based on the reaction of chloride with silver nitrate and the determination of turbidity of silver chloride formed. The absorbance was measured at 385 nm. The method was tested under various conditions, and we confirmed an optimal operation with 2 mL 1:4 (v/v) nitric acid, 2 mL 1.5 g L−1 gelatin, 5 mL 0.5% silver nitrate in a total volume of 50 mL, mixed and heated at 60 °C for 10 min. The range of linearity and the detection limit were 0.4–24 mg L−1 and 0.2 mg L−1, respectively. The relative standard deviations and the recovery were 0.83% to 2.87% and 93.74% to 103.6%, respectively. The accuracy of this method was comparable with Volhard method, and it was cheap and successfully applied to determine sodium chloride in salted fish.
Physico‐chemical and acceptability of rabadi (a fermented soya flour product) as affected by cooking and fermentation time
Authors: Gupta Vineeta , Nagar Ranjana
Published: April 2008

Various food‐processing techniques like malting, roasting, soaking, germination, fermentation, etc. are known to enhance nutritive value and acceptability of different food products. The present study deals with the biochemical analysis and acceptability tests of soya flour rabadi, which was made by fermentation before and after cooking at different time intervals. There was a trend towards increase in moisture, ash, total carbohydrate, calcium, total soluble sugars, reducing sugars, non‐reducing sugars, amylase, glutamate oxaloacetate transaminase enzymatic activities and titrable acidity, whereras a trend towards decrease was found in crude protein, fat, fibre, energy, starch, total phenols and glutamate pyruvate transaminase enzyme activity. Major biochemical changes occurred after 8 h fermentation. In sensory evaluation also, samples fermented for 4 and 8 h after cooking got higher scores than all other samples.
Type IV pili: e pluribus unum?
Authors: Pelicic Vladimir
Published: April 2008

The widespread role of pili as colonization factors in pathogens has long been recognized in Gram‐negative bacteria and more recently in Gram‐positive bacteria, making the study of these hair‐like filaments a perennial hot topic for research. No other pili are found in as many or as diverse bacteria as type IV pili. This is likely a consequence of their ancient origin and unique ability to promote multiple and strikingly different phenotypes such as attachment to surfaces, aggregation, uptake of DNA during transformation, motility, etc. Two decades of investigations in several model species have shed some light on the structure of these filaments and the molecular basis of some of the properties they confer. Moreover, recent discoveries have led to a better knowledge of the genetic basis and molecular mechanisms of type IV pili biogenesis. This brings us a few steps closer to understanding how these filaments are produced, but leaves us wondering whether (as in the famous motto that inspired the title) out of the many models studied will emerge one unifying mechanism.