bluuebunny/crossref_metadata_2025_split huggingface dataset:
The origins of postmating reproductive isolation: testing hypotheses in the grasshopper Chorthippus parallelus
Authors: Tregenza T. , Pritchard V. L. , Butlin R. K. 
Published: March 2004

AbstractAlthough there are several well‐established hypotheses for the origins of postmating isolation during allopatric divergence, there have been very few attempts to determine their relative importance in nature. We have developed an approach based on knowledge of the differing evolutionary histories of populations within species that allows systematic comparison of the predictions of these hypotheses. In previous work, we have applied this methodology to mating signal variation and premating reproductive isolation between populations of the meadow grasshopper Chorthippus parallelus. Here we review the principles behind our approach and report a study measuring postmating isolation in the same set of populations. The populations have known and differing evolutionary histories and relationships resulting from the colonization of northern Europe following the last glaciation. We use a maximum‐likelihood analysis to compare the observed pattern of postmating isolation with the predictions of the hypotheses that isolation primarily evolves either as a result of gradual accumulation of mutations in allopatry, or through processes associated with colonization, such as founder events. We also quantify the extent to which degree of postmating isolation can be predicted by genetic distance. Our results suggest that although there is only a weak correlation between genetic distance and postmating isolation, long periods of allopatry do lead to postmating isolation. In contrast to the pattern of premating isolation described in our previous study, colonization does not seem to be associated with increased postmating isolation.
Ecological diversity and speciation in land snails of the genus Mandarina from the Bonin Islands
Authors: Chiba S. 
Published: March 2004

AbstractEndemic land snails of the genus Mandarina of the oceanic Bonin Islands offer an example of habitat and character divergence among closely related species. The molecular phylogenies of Mandarina show that a divergence of arboreal, semiarboreal, and ground‐dwelling species has occurred repeatedly in different times, areas, and lineages. Ecological diversification is suggested to be important for the coexistence of Mandarina species based on the facts that sympatric species are typically highly differentiated ecologically and morphologically, and that species occupying similar habitats do not coexist. The ecological diversification of Mandarina has occurred without much genetic divergence compared with that of its mainland relatives. This suggests that morphological and ecological diversifications are accelerated in depauperate environments where there are fewer competitors and predators. Although the details of the reproductive isolation mechanisms are not understood and further examination is needed, the rapid evolution of prezygotic isolation is the main cause of speciation in Mandarina. In particular, ecological diversification may be an effective barrier to gene exchange between two species. Because of incomplete postmating isolation and the lower genetic divergence among species of Mandarina, breakdowns of reproductive isolation have frequently occurred as a result of habitat change. It is important to estimate the effect of hybridization on species diversification in future studies.
Ecology meets molecular genetics in Arabidopsis
Authors: Shimizu K. K. 
Published: March 2004

AbstractArabidopsis thaliana has been used as a model plant for molecular genetics studies. Recently, Arabidopsis has been utilized in an increasing number of ecological and evolutionary studies. These studies are beginning to explain three “black boxes” of ecology: the nature of the mutations responsible for phenotypic variation, female–male interactions in the pistil, and the genetic basis of speciation. Among the advances are the inclusive fitness of haploid gametophytes, the testing of the arms‐race model, morphological diversity, and reproductive isolation. Important methods include quantitative trait locus (QTL) mapping and molecular population genetics. Most significantly, natural variations of various aspects are now available via the taxonomic revision of its closely related species, and by the worldwide collection of accessions. Some conspicuous works using maize, Drosophila, and other species will be also discussed.
Scramble competition in Callosobruchus analis (Coleoptera: Bruchidae)
Authors: Mano H. , Toquenaga Y. , Fujii K. 
Published: March 2004

AbstractLarvae of Callosobruchus analis have been used as model organisms of contest competition where only one adult can emerge from a bean irrespective of initial larval density. A new strain of C. analis found recently exhibited a higher rate of two‐adult emergence than a reference strain used in previous studies of larval competition. The higher rate of two‐adult emergence of the new strain to exhibit such behavior was investigated in terms of resource requirement examining elytron length and change in larval weight. The results showed the new strain had lower resource requirements than the reference strain. A lower encounter rate with opponents within a bean may prevent interference competition, as resource requirement becomes lower. We inferred that the new strain was not a scramble competitor but a contest competitor with small resource requirements. We also attempted to estimate the results of larval competition between the two strains, which differ in their resource requirement.
Estivation and hibernation of Pieris brassicae (L.) in southern Spain: synchronization of two complex behavioral patterns
Authors: Spieth H. R. 
Published: March 2004

AbstractThe large white butterfly, Pieris brassicae, has an unusually complex life‐history in its southernmost range in Western Europe. This complexity results (1) from two developmental rests, a short‐day induced hibernation and a long‐day induced estivation response, and (2) from the exceptionally early appearance of the first adult generation in January/February and a subsequent winter diapause in some of their progeny. It was found that in spring and autumn, different generations are faced with critical photophases which induce hibernation or estivation, with the consequence that in five out of six generations per year, only some develop directly whereas the others enter a dormancy phase. To assess the implications of this high number of optional responses on the generation succession, the development time was studied at various photoperiods and temperatures. The results showed that a threshold response determines the duration of estivation. With unchanged summer conditions (daylengths ≥15 h) estivation lasts on average 18–19 weeks, while with autumn conditions (daylengths ≤14 h) it lasts only 7 weeks. A change of photophases from ≥15 h to ≤14 h terminates estivation within about 3–5 weeks, slightly depending on the pupal exposure time in summer conditions. The duration of estivation is not affected by temperature or by the photophases experienced by the caterpillars. The winter diapause lasts 18–19 weeks on average with winter conditions (12°C/10.30 h light), but only 8–10 weeks with late spring conditions (21°C/15 h light). These results were used to assess the effects on the population phenology, with the finding that despite the different developmental pathways, a desynchronization of the generation succession is largely prevented. Estivation, hibernation, and direct development at different seasons are well adjusted to a common phenological pattern of a continuously reproducing population. This pattern of activity covers a cryptic dormant subpopulation, and could not have been deduced by field observations.
Herbivore abundance is independent of weather? A 20‐year study of a galling aphid Baizongia pistaciae (Homoptera: Aphidoidea)
Authors: Wool D. 
Published: March 2004

AbstractThe gall abundance of Baizongia pistaciae (L.) (Pemphiginae: Fordini) on marked Pistacia palaestina trees (Anacardiaceae) was monitored for 20 years at two natural sites in Israel (Carmel, in the center of the host distribution, and Beit Guvrin, near its southern limit), and in the botanical gardens of Tel Aviv University. Gall abundance varied between zero and 500 galls/tree and fluctuated from year to year. The analysis aimed at a diagnosis of the underlying causes of the temporal changes in gall abundance. Weather variables were expected to synchronize gall abundance on most trees on the same site. There was little indication of synchrony among trees in most years. Correlations of mean gall abundance with weather variables were low (<0.4, explaining <16% of the variation) and almost none were significant. The temporal pattern of gall abundance was analyzed for every tree separately (the “autecological” paradigm). There was no convincing evidence of self‐regulation (density‐dependence) in gall abundance on any tree, although the rate of change in abundance tended to decrease with increasing density on some trees. At one site (Carmel), significantly more abundance peaks (1 SD above the mean) occurred in “wet” years (precipitation above average) than in “dry” years. This pattern was not observed at the other sites. The biannual fluctuations in abundance, observed in the first 10 years of the study, were far less clear when the 20‐year sequence was analyzed. If the causative mechanism is tree stress – as assumed previously – then the biannual pattern may not be expected except in years of favorable conditions, when gall abundance is high enough to drain the tree of resources and cause a lower gall abundance the following year. The life cycle of galling aphids is very complex. A clone enclosed in a gall on a tree alternates with a subterranean population on the roots of herbaceous plants, with two migratory phases in between. Moreover, a sequence of parthenogenetic generations is interrupted by a single event of sexual reproduction. In B. pistaciae, this cycle takes two years to complete. Regulating mechanisms of gall abundance at the different stages may work in different directions, canceling each other out. I suggest that direct effects of weather on the aphids at any stage of their complex life cycle may be obscured when the net result (gall abundance) is studied. Weather effects may be detectable only when it is extremely favorable or unfavorable for the aphids (or the host plant).
The effect of osteogenic growth factors on bone growth into a ceramic filled defect around an implant
Authors: Clarke S. A. , Brooks R. A. , Lee P. T. H. , Rushton N. 
Published: March 2004

AbstractCurrently available synthetic bone substitutes perform poorly compared to autograft. It is hoped that by adding osteogenic growth factors to the materials, new bone formation could be increased and the clinical outcome improved. In this study, IGF‐1, bFGF and TGFβl, alone and in combination, were absorbed onto a carrier of β‐tricalcium phosphate (βTCP) and implanted into a defect around a hydroxyapatite‐coated, stainless steel implant in the proximal tibia of rat in a model of revision arthroplasty. Animals were sacrificed at 6 and 26 weeks for routine histology and histomorphometry and mechanical push out tests. The results show that only bFGF had a significant effect on ceramic resorption. The groups that received bFGF and bFGF in combination with TGFβl had smaller and fewer βTCP particles remaining in the defect at 6 and 26 weeks. No growth factor combination significantly enhanced new bone formation or the mechanical strength of the implant. These results indicate that, of the growth factors tested, only bFGF had any beneficial effect on the host response to the implant, perhaps by delaying osteoblast differentiation and thereby prolonging osteoclast access to the ceramic. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
POLYCYCLIC AROMATIC HYDROCARBONS IN THE ATMOSPHERE: MONITORING, SOURCES, SINKS AND FATE. I: MONITORING AND SOURCES
Authors: Pozzoli Luca , Gilardoni Stefania , Perrone Maria Grazia , de Gennaro Gianluigi , de Rienzo Massimo , Vione Davide 
Published: March 2004

AbstractThis is the first of a series of two papers intended to review the state‐of‐the‐art knowledge on atmospheric PAHs, concerning their monitoring, sources and transformation processes in the atmosphere. The monitoring section briefly introduces this class of compounds, mainly focusing on the 16 PAHs indicated by the US‐EPA as priority pollutants. These compounds undergo partitioning between the gas phase and particulate, which has to be considered in the choice of the sampling methodology. Furthermore, sampling artifacts may arise from further phase transfers inside the sampling device. After sampling, extraction, clean up and detection/quantification procedures will follow. They are closely related since the choice of the extraction technique will heavily condition the clean‐up step, and both procedures will place demands on the performance of the detection technique (usually GC‐MS or HPLC). This is particularly true in the case of complex samples such as those arising from atmospheric sampling. The sources of atmospheric PAHs are then discussed with a particular focus on receptor models, which can allow the apportionment of PAH sources based on concentration data that can be routinely obtained by pollution control networks.
SELECTIVE TRANSITION METAL EXTRACTION BY REVERSE MICELLES
Authors: Caselli Maurizio , Mangone Annarosa , Pellegrino Teresa , Traini Angela 
Published: March 2004

AbstractIn this report we have studied the extraction of a series of heavy metals ions (Cu2+, Ni2+, Fe3+, Cr3+, CrO42‐) from water bulk solutions by means of reverse micelles. The parameters explored are the nature and concentration of the accompanying electrolyte, as well as the surfactant nature and its concentration. The extracted metals can be recovered and eventually concentrated in a new water solution carrying out a back extraction.The extracted amount of metal is strongly dependent on the charge of the metal to be extracted. Therefore the extracted water solution is enriched in higher charge metal. Anions of amphoteric metals, like the chromate ions, can be quantitatively separated from their positive cations, like Cr3+ by properly choosing the cationic or the anionic surfactants.The transfer of the metal is essentially controlled by electrostatic forces. A model based on the Poisson‐Boltzmann distribution allow us to get the potential profile inside the water pool by determining the concentrations of the surfactant counter ions. From the potential profile and mass balance it is possible calculate the extraction percentage.
PENICILLAMINE DISULFIDE (PNS) AND ALKALINE CATIONS
Authors: Apruzzese Fabrizio , Bottari Emilio , Festa Maria Rosa 
Published: March 2004

AbstractD‐penicillamine disulfide (PNS) shows protolytic properties and is able to form complexes with cations, because it has two aminic groups and two carboxylic groups. The four protonation constants of its deprotonated species were determined by means of electromotive force (e.m.f.) measurements of a galvanic cell involving a glass electrode at 25°C and in a constant ionic medium constituted by N(CH3)4Cl 3.00 or 1.00 mol dm‐3. At 25°C and in 3.00 mol dm‐3 N(CH3)4Cl as ionic medium, equilibria taking place between PNS and lithium, sodium and potassium ions were investigated. Experimental data, again obtained from e.m.f. measurements, were explained by assuming the formation of species of the type MH2PNS ed M2H2PNS, where M indicates a cation. Stability constants for each proposed species were calculated. A comparison with cystine is discussed.
HEAVY METAL IN SEDIMENTS AND BIOACCUMULATION IN THE BIVALVE Corbula gibba IN A DRILLING DISCHARGE AREA
Authors: Mauri Marina , Spagnoli Federico , Marcaccio Marco 
Published: March 2004

AbstractThe longterm bioavailability of heavy metals in sediments of a Northern Adriatic Sea shelf area affected by drilling mud and cutting discharges was discussed. Levels of Mn, Cu, Cr, Zn and Pb in different geochemical phases of the sediment and in soft tissues of the bivalve Corbula gibba were recorded and the relationships between biological and geochemical metal investigated. Total metal content, acetic acid extractable‐, exchangeable‐, carbonate‐, easily reducible‐, moderately reducible‐, oxidable‐ and residual‐fractions were determined on sediment samples. Corbula gibba was collected from wet sediments at the same times and sites, and the soft‐tissue metal contents were determined. Correlations show that the fractions with greatest bioavailability are the exchangeable and carbonate for Cr and the exchangeable, carbonate, easily and moderately reducible fractions for Zn. Data also show a possible bioavailability of Pb only from the residual fraction, consisting of very resistant matter of more recent anthropogenic origin. Near the platform, total Mn content in sediments and in C. gibba tissues show a strong correlation suggesting that this organism is sensitive to variations of the Mn‐oxi‐hydroxides superficial film. No relationships were found between biological and sediment‐bound Cu, however the discharged muds did not cause Cu enrichment. The metal fraction determined by weak acetic acid extraction at no point seems related to metal levels in Corbula gibba.
VALIDATION OF AN HPLC METHOD FOR THE DETERMINATION OF FLEROXACIN AND ITS PHOTO‐DEGRADATION PRODUCTS IN PHARMACEUTICAL FORMS
Authors: Djurdjevic Predrag , Laban Aleksandra , Jelikic‐Stankov Milena 
Published: March 2004

AbstractHPLC determination of fleroxacin in dosage forms was carried out using either reversed‐phase column YMC pack ODS‐AQ or Supelco LC Hisep shielded hydrophobic phase column, with UV detection at 280 nm. The mobile phase for ODS column consisted of 50:50:0.5 v/v/v and for Hisep column 15:85:0.5 v/v/v acetonitrile‐water‐triethylamine. The pH of the mobile phase was adjusted to 6.30 for ODS column and to 6.85 for Hisep column, with H3PO4. Linear response was obtained in the concentration range of fleroxacin between 0.01 and 1.30 μg/mL. Detection limit was 4.8 ng/mL. Recovery test in the determination of fleroxacin in “Quinodis” tablets (Hoffmann La Roche, nominal mass 400 or 200 mg) was 98‐101% for both columns. The effect of the composition and pH of the mobile phase on spectra, retention time and dissociation constants of fleroxacin was discussed. The proposed method could be also used for separation of the photo‐degradation products of fleroxacin. Ten degradation products were separated on the ODS‐AQ column, thus confirming the suitability of the proposed method for stability study of fleroxacin in pharmaceuticals.
Assessment of occupational safety and health programs in small businesses
Authors: Barbeau Elizabeth , Roelofs Cora , Youngstrom Richard , Sorensen Glorian , Stoddard Anne , LaMontagne Anthony D. 
Published: March 2004

AbstractBackgroundOccupational safety and health (OSH) programs are a strategy for protecting workers' health, yet there are few peer‐reviewed reports on methods for assessing them, or on the prevalent characteristics of OSH programs, especially in small businesses.MethodsWe adapted an occupational safety and health administration (OSHA) survey instrument to assess: management commitment and employee participation, workplace analysis, hazard prevention and control, and education and training. This was supplemented by a series of open‐ended questions. We administered the survey in 25 small worksites.ResultsScores for each element ranged widely, with distribution of most scores being positively skewed. Barriers to addressing OSH included lack of time and in‐house expertise, and production pressures. External agents, including corporate parents, liability insurers, and OSHA, played an important role in motivating OSH programs.ConclusionsSmall businesses were able to mount comprehensive programs, however, they may rely on outside resources for this task. Being small may not be a barrier to meeting the requirements of an OSHA program management rule. Am. J. Ind. Med. 45:371–379, 2004. © 2004 Wiley‐Liss, Inc.
Heat illness in the U.S. mining industry
Authors: Michael Donoghue A. 
Published: March 2004

AbstractBackgroundHeat illness is relatively common in the underground metalliferous mines of South Africa and Australia. Little is known about heat illness in other forms of mining and there have been no studies of heat illness in the US mining industry.MethodsMine Safety and Health Administration (MSHA) accident, injury, illness, and employment data were used to study heat illness reported by the US mining industry from January 1, 1983 to December 31, 2001.ResultsFive hundred thirty eight cases of heat illness were reported. None of these cases were fatal. Four hundred twenty seven cases (79.4%) occurred in the summer months of June, July, and August. Incidence rates of heat illness in underground mining ranged from 0.00275/106 person‐hours for coal, to 0.168/106 person‐hours for metal, rate‐ratio = 61.1 (P < 0.001). Incidence rates in surface mining ranged from 0.0265/106 person‐hours for coal, to 0.0644/106 person‐hours for stone, rate‐ratio = 2.43 (P < 0.001). Incidence rates in mills/preparation plants ranged from 0.0255/106 person‐hours for coal, to 0.417/106 person‐hours for stone, rate‐ratio = 16.4 (P < 0.001).ConclusionsHeat illness occurs most frequently in stone mills, metal mills, and underground metal mines. Preventive measures should target the summer months of June, July, and August. Am. J. Ind. Med. 45:351–356, 2004. © 2004 Wiley‐Liss, Inc.
More evidence of the need for an ergonomic standard
Authors: Biddle Jeff , Roberts Karen 
Published: March 2004

AbstractBackgroundIn 1999, the Occupational Safety and Health Administration (OSHA) proposed regulations designed to reduce work related inquiries by limiting worker exposure to “ergonomic risk factors.” Congress subsequently overturned the regulations. We provide additional evidence on earnings losses attributable to musculoskeletal disorders (MSDs), and thus on the need for an ergonomic standard.MethodsRegression techniques are used to analyze data from a survey of injured workers that has been matched to employer‐reported earnings data covering pre‐ and post‐injury periods, and to workers' compensation claims records.ResultsMSDs lead to large and persistent earnings losses. Cost estimates used by OSHA to justify the 1999 EPS are corroborated. Losses are greatest among workers who file workers compensation claims, but nonclaimants also have losses.ConclusionsEarnings losses and lost productivity associated with work‐related MSDs are substantial and an ergonomic standard could be cost effective. Am. J. Ind. Med. 45:329–337, 2004. © 2004 Wiley‐Liss, Inc.