bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved Detection Using Negative Elevation Angles for Mountaintop WSR-88Ds. Part III: Simulations of Shallow Convective Activity over and around Lake Ontario
Authors: Brown Rodger A. , Niziol Thomas A. , Donaldson Norman R. , Joe Paul I. , Wood Vincent T.
Published: August 2007

During the winter, lake-effect snowstorms that form over Lake Ontario represent a significant weather hazard for the populace around the lake. These storms, which typically are only 2 km deep, frequently can produce narrow swaths (20–50 km wide) of heavy snowfall (2–5 cm h−1 or more) that extend 50–75 km inland over populated areas. Subtle changes in the low-altitude flow direction can mean the difference between accumulations that last for 1–2 h and accumulations that last 24 h or more at a given location. Therefore, it is vital that radars surrounding the lake are able to detect the presence and strength of these shallow storms. Starting in 2002, the Canadian operational radars on the northern side of the lake at King City, Ontario, and Franktown, Ontario, began using elevation angles of as low as −0.1° and 0.0°, respectively, during the winter to more accurately estimate snowfall rates at the surface. Meanwhile, Weather Surveillance Radars-1988 Doppler in New York State on the southern and eastern sides of the lake—Buffalo (KBUF), Binghamton (KBGM), and Montague (KTYX)—all operate at 0.5° and above. KTYX is located on a plateau that overlooks the lake from the east at a height of 0.5 km. With its upward-pointing radar beams, KTYX’s detection of shallow lake-effect snowstorms is limited to the eastern quarter of the lake and surrounding terrain. The purpose of this paper is to show—through simulations—the dramatic increase in snowstorm coverage that would be possible if KTYX were able to scan downward toward the lake’s surface. Furthermore, if KBUF and KBGM were to scan as low as 0.2°, detection of at least the upper portions of lake-effect storms over Lake Ontario and all of the surrounding land area by the five radars would be complete. Overlake coverage in the lower half (0–1 km) of the typical lake-effect snowstorm would increase from about 40% to about 85%, resulting in better estimates of snowfall rates in landfalling snowbands over a much broader area.
An Experiment to Measure the Value of Statistical Probability Forecasts for Airports
Authors: Keith Ross , Leyton Stephen M.
Published: August 2007

The economic value of weather forecasts for airports for commercial aviation is investigated by introducing financial data into the decision-making process for fuel carriage by aircraft. Using specific operating costs for a given flight, an optimal decision probability threshold can be calculated that identifies whether that flight should carry extra fuel, in case of adverse weather conditions and subsequent diversion. Forecasts of these adverse conditions can then be applied to a critical threshold to make a real-time decision regarding the carriage of additional fuel. This study focuses on forecasts of low ceiling and/or reduced visibility and their corresponding impact on forecast value for flights arriving at three major airports in the United States. Eighteen daily flights by American Airlines were examined during a 14-month period, a total of approximately 7500 flights. Using operating cost data from this period, a critical decision threshold was derived for each daily flight. Two sets of forecasts, statistically derived probabilistic forecasts and National Weather Service terminal aerodrome forecasts (TAFs), were then applied to each flight’s fuel carriage decision-making process. The probabilistic forecasts, which utilize regional surface observations, were generated for the destination airport with a lead time appropriate to the airline’s flight planning time. If the forecast probability of adverse weather was greater than the critical decision threshold for a given flight, then additional fuel was deemed necessary for that flight. The categorical TAFs that corresponded timewise to the developed probabilistic forecasts were obtained for each location. For this study, a categorical “yes” forecast denotes the expectation that the visibility and/or cloud ceiling conditions are such that extra fuel is required, while a categorical “no” forecast does not require extra fuel. The analysis presented herein indicates that by using statistical, probabilistic forecasts rather than categorical forecasts, a significant saving is made in operating costs. This is probably because of a more optimal balance between false alarms and misses for each flight, rather than more “accurate” forecasts per se. This is the mechanism by which probabilistic forecasts create value, rather than increasing the number of hits and correct rejections and/or decreasing the number of false alarms and misses. For each of the flights investigated in this study, the total cost of using probabilistic forecasts was less than that of using TAFs. An average of $23,000 is saved per flight during this 14-month period. Projecting these figures over all American Airlines flights, a potential annual savings of approximately $50 million in operating costs would be realized by using probabilistic forecasts of adverse landing weather conditions instead of the traditional TAF.
Experimental study of single sided sheet to tube resistance spot welding
Authors: Yang H. G. , Hu S. J. , Zhang Y. S. , Li Y. B. , Lai X. M.
Published: August 2007

To reduce weight and improve performance, hydroformed tubes are being widely used in automotive structure fabrication and the single sided sheet to tube resistance spot welding (SSRSW) is considered as a feasible method for joining a tube to other parts. However, in the sheet to tube SSRSW process, it is difficult to assure welding quality because of large welding deformation due to a lack of support inside the tube. The present paper investigates the influences of welding parameters, such as electrode force and welding current, on the welding deformation and quality of the sheet to tube SSRSW using electrode displacement and tensile shear tests. The effects of different electrode force patterns on the welding quality are investigated utilising the force characteristics of a servo gun. It is found that the welding deformation is influenced by both the electrode force and the welding current, and the tensile shear strength declines with larger electrode force and higher welding current. However, the tensile strength could be enhanced significantly and the welding deformation decreased greatly by reducing the electrode force in the welding stage or holding stage. In order to decrease manufacturing cost and improve weld quality, the reduced electrode force is recommended for the sheet to tube SSRSW process.
Novel rotation arc system for narrow gap MAG welding
Authors: Wang J. Y. , Ren Y. S. , Yang F. , Guo H. B.
Published: August 2007

The present paper develops a hollow axis motor driven high speed rotation arc system for narrow gap welding (NGW), and introduces the features of this system. Some welding experiments were then carried out to investigate the characteristics of welding wire melting and weld formation for this new process. Experimental results show that the melting rate of wire increases and the residual melting ball diameter of wire tip decreases respectively with an increase in rotation speed, and this melting rate is higher in pulsed welding and NGW respectively than in dc and flat plate welding. Furthermore, the arc rotation can obviously improve the penetration into NGW groove sidewalls and bead shape, and thus the system has been used to weld practical NGW joints successfully.
Effect of welding procedure on texture and strength of nickel based weld metal
Authors: Gustafsson M. , Thuvander M. , Bergqvist E.-L. , Keehan E. , Karlsson L.
Published: August 2007

The influence of welding procedure on the relation between texture and tensile strength was studied for shielded metal arc nickel based weld metals. Mechanical properties, microstructure and crystallography were characterised using various techniques including electron back-scattered diffraction and X-ray diffraction. Results showed a correlation between texture and strength. The tensile strength was higher when the predominant direction of grain growth was inclined towards, rather than perpendicular to the test direction. This was seen most clearly for vertical-up welds and for higher energy input horizontal welds tested. The weld pool shape affects grain growth direction and thereby texture. Consequently the welding procedure can to some extent be used to control the tensile strength.
Failure behaviour of laser spot welds of TRIP800 steel sheets under coach–peel loading
Authors: Daneshpour S. , Riekehr S. , Koçak M. , Ventzke V. , Koruk A. I.
Published: August 2007

This study is carried out to investigate the laser spot welds (LSWs) of advanced high strength steel sheets of 1·0 mm thickness for application to the automotive industry. Mechanical properties and failure behaviour of LSWs for transformation induced plasticity steel sheets (TRIP800) subjected to monotonic coach–peel loading are investigated by experimental and finite element (FE) simulation methods. Microstucture of LSW and fracture surfaces of the welded specimens were examined by scanning electron microscopy (SEM) to describe the microstructural features and to clarify the crack initiation mechanism respectively. Based on simulation solutions equivalent plastic strain was obtained to describe local deformation of LSW joints. Experimental results revealed a ‘plug type’ of failure mode of the circular LSW joints under ‘peel–coach’ loading condition. This type of ductile failure is the most common failure mode for spot welds used in the automotive industry. Numerical simulation of damage process was compared with experimental results and this revealed that fracture path was successfully predicted.
Statistics of signature images for arc welding fault detection
Authors: Simpson S. W.
Published: August 2007

The present work covers the statistical analysis of signature images for weld quality monitoring and fault detection. Welding signature images are two-dimensional histograms of voltage and current data. Signatures from production welding are compared with reference good welding using a statistical analysis of both the principal components, which are fitted with shifted normal distributions, and the remainders not explained by the principal components, which are fitted with a multidimensional normal distribution. A signature basis set is employed, allowing efficient real time computations. The statistical data fits are illustrated with data from overlap welds, and examples of fault detection with out of position welds are given.
Gene expression studies of developing bovine longissimusmuscle from two different beef cattle breeds
Authors: Lehnert Sigrid A , Reverter Antonio , Byrne Keren A , Wang Yonghong , Nattrass Greg S , Hudson Nicholas J , Greenwood Paul L
Published: August 2007

Background

The muscle fiber number and fiber composition of muscle is largely determined during prenatal development. In order to discover genes that are involved in determining adult muscle phenotypes, we studied the gene expression profile of developing fetal bovine longissimus muscle from animals with two different genetic backgrounds using a bovine cDNA microarray. Fetal longissimus muscle was sampled at 4 stages of myogenesis and muscle maturation: primary myogenesis (d 60), secondary myogenesis (d 135), as well as beginning (d 195) and final stages (birth) of functional differentiation of muscle fibers. All fetuses and newborns (total n = 24) were from Hereford dams and crossed with either Wagyu (high intramuscular fat) or Piedmontese (GDF8 mutant) sires, genotypes that vary markedly in muscle and compositional characteristics later in postnatal life.

Results

We obtained expression profiles of three individuals for each time point and genotype to allow comparisons across time and between sire breeds. Quantitative reverse transcription-PCR analysis of RNA from developing longissimus muscle was able to validate the differential expression patterns observed for a selection of differentially expressed genes, with one exception. We detected large-scale changes in temporal gene expression between the four developmental stages in genes coding for extracellular matrix and for muscle fiber structural and metabolic proteins. FSTL1 and IGFBP5 were two genes implicated in growth and differentiation that showed developmentally regulated expression levels in fetal muscle. An abundantly expressed gene with no functional annotation was found to be developmentally regulated in the same manner as muscle structural proteins. We also observed differences in gene expression profiles between the two different sire breeds. Wagyu-sired calves showed higher expression of fatty acid binding protein 5 (FABP5) RNA at birth. The developing longissimus muscle of fetuses carrying the Piedmontese mutation shows an emphasis on glycolytic muscle biochemistry and a large-scale up-regulation of the translational machinery at birth. We also document evidence for timing differences in differentiation events between the two breeds.

Conclusion

Taken together, these findings provide a detailed description of molecular events accompanying skeletal muscle differentiation in the bovine, as well as gene expression differences that may underpin the phenotype differences between the two breeds. In addition, this study has highlighted a non-coding RNA, which is abundantly expressed and developmentally regulated in bovine fetal muscle.
Formamide as the main building block in the origin of nucleic acids
Authors: Costanzo Giovanna , Saladino Raffaele , Crestini Claudia , Ciciriello Fabiana , Di Mauro Ernesto
Published: August 2007

The simplest molecules grouping the four most common elements of the universe H,C,O and N (with the exception of the biologically inert He) are isocyanate HNCO and formamide H2NCOH. Reasons for the availability of formamide on prebiotic Earth are presented. We review evidence showing that formamide in the presence of largely available catalysts and by moderate heating yields the complete set of nucleic bases necessary for the formation of nucleic acids. Formamide also favours the formation of acyclonucleosides and the phosphorylation and trans-phosphorylation of nucleosides, thus providing a plausible chemical frame for the passage from a simple one-carbon compound to nucleic polymers. Physico-chemical conditions exist in which formamide favours the stability of the phosphoester bonds in nucleic polymers relative to that of the same bonds in monomers. Starting from a formamide-laden environment subject only to the laws of chemistry, a hypothesis is outlined sketching the passage towards an aqueous world in which Darwinian rules apply.
Phylogenomics of species from four genera of New World monkeys by flow sorting and reciprocal chromosome painting
Authors: Dumas Francesca , Stanyon Roscoe , Sineo Luca , Stone Gary , Bigoni Francesca
Published: August 2007

Background

The taxonomic and phylogenetic relationships of New World monkeys (Platyrrhini) are difficult to distinguish on the basis of morphology and because diagnostic fossils are rare. Recently, molecular data have led to a radical revision of the traditional taxonomy and phylogeny of these primates. Here we examine new hypotheses of platyrrhine evolutionary relationships by reciprocal chromosome painting after chromosome flow sorting of species belonging to four genera of platyrrhines included in the Cebidae family: Callithrix argentata (silvered-marmoset), Cebuella pygmaea (pygmy marmoset), Callimico goeldii (Goeldi's marmoset) and Saimiri sciureus (squirrel monkey). This is the first report of reciprocal painting in marmosets.

Results

The paints made from chromosome flow sorting of the four platyrrhine monkeys provided from 42 to 45 hybridization signals on human metaphases. The reciprocal painting of monkey probes on human chromosomes revealed that 21 breakpoints are common to all four studied species. There are only three additional breakpoints. A breakpoint on human chromosome 13 was found in Callithrix argentata, Cebuella pygmaea and Callimico goeldii, but not in Saimiri sciureus. There are two additional breakpoints on human chromosome 5: one is specific to squirrel monkeys, and the other to Goeldi's marmoset.

Conclusion

The reciprocal painting results support the molecular genomic assemblage of Cebidae. We demonstrated that the five chromosome associations previously hypothesized to phylogenetically link tamarins and marmosets are homologous and represent derived chromosome rearrangements. Four of these derived homologous associations tightly nest Callimico goeldii with marmosets. One derived association 2/15 may place squirrel monkeys within the Cebidae assemblage. An apparently common breakpoint on chromosome 5q33 found in both Saimiri and Aotus nancymae could be evidence of a phylogenetic link between these species. Comparison with previous reports shows that many syntenic associations found in platyrrhines have the same breakpoints and are homologous, derived rearrangements showing that the New World monkeys are a closely related group of species. Our data support the hypothesis that the ancestral karyotype of the Platyrrhini has a diploid number of 2n = 54 and is almost identical to that found today in capuchin monkeys; congruent with a basal position of the Cebidae among platyrrhine families.
Montmorillonite protection of an UV-irradiated hairpin ribozyme: evolution of the RNA world in a mineral environment
Authors: Biondi Elisa , Branciamore Sergio , Maurel Marie-Christine , Gallori Enzo
Published: August 2007

Background

The hypothesis of an RNA-based origin of life, known as the "RNA world", is strongly affected by the hostile environmental conditions probably present in the early Earth. In particular, strong UV and X-ray radiations could have been a major obstacle to the formation and evolution of the first biomolecules. In 1951, J. D. Bernal first proposed that clay minerals could have served as the sites of accumulation and protection from degradation of the first biopolymers, providing the right physical setting for the evolution of more complex systems. Numerous subsequent experimental studies have reinforced this hypothesis.

Results

The ability of the possibly widespread prebiotic, clay mineral montmorillonite to protect the catalytic RNA molecule ADHR1 (Adenine Dependent Hairpin Ribozyme 1) from UV-induced damages was experimentally checked. In particular, the self-cleavage reaction of the ribozyme was evaluated after UV-irradiation of the molecule in the absence or presence of clay particles. Results obtained showed a three-fold retention of the self-cleavage activity of the montmorillonite-protected molecule, with respect to the same reaction performed by the ribozyme irradiated in the absence of the clay.

Conclusion

These results provide a suggestion with which RNA, or RNA-like molecules, could have overcame the problem of protection from UV irradiation in the RNA world era, and suggest that a clay-rich environment could have favoured not only the formation of first genetic molecules, but also their evolution towards increasingly complex molecular organization.
The primordial metabolism: an ancestral interconnection between leucine, arginine, and lysine biosynthesis
Authors: Fondi Marco , Brilli Matteo , Emiliani Giovanni , Paffetti Donatella , Fani Renato
Published: August 2007

Background

It is generally assumed that primordial cells had small genomes with simple genes coding for enzymes able to react with a wide range of chemically related substrates, interconnecting different metabolic routes. New genes coding for enzymes with a narrowed substrate specificity arose by paralogous duplication(s) of ancestral ones and evolutionary divergence. In this way new metabolic pathways were built up by primordial cells. Useful hints to disclose the origin and evolution of ancestral metabolic routes and their interconnections can be obtained by comparing sequences of enzymes involved in the same or different metabolic routes. From this viewpoint, the lysine, arginine, and leucine biosynthetic routes represent very interesting study-models. Some of the lys, arg and leu genes are paralogs; this led to the suggestion that their ancestor genes might interconnect the three pathways. The aim of this work was to trace the evolutionary pathway leading to the appearance of the extant biosynthetic routes and to try to disclose the interrelationships existing between them and other pathways in the early stages of cellular evolution.

Results

The comparative analysis of the genes involved in the biosynthesis of lysine, leucine, and arginine, their phylogenetic distribution and analysis revealed that the extant metabolic "grids" and their interrelationships might be the outcome of a cascade of duplication of ancestral genes that, according to the patchwork hypothesis, coded for unspecific enzymes able to react with a wide range of substrates. These genes belonged to a single common pathway in which the three biosynthetic routes were highly interconnected between them and also to methionine, threonine, and cell wall biosynthesis. A possible evolutionary model leading to the extant metabolic scenarios was also depicted.

Conclusion

The whole body of data obtained in this work suggests that primordial cells synthesized leucine, lysine, and arginine through a single common metabolic pathway, whose genes underwent a set of duplication events, most of which can have predated the appearance of the last common universal ancestor of the three cell domains (Archaea, Bacteria, and Eucaryotes). The model proposes a relative timing for the appearance of the three routes and also suggests a possible evolutionary pathway for the assembly of bacterial cell-wall.
Global transcription profiling reveals differential responses to chronic nitrogen stress and putative nitrogen regulatory components in Arabidopsis
Authors: Bi Yong-Mei , Wang Rong-Lin , Zhu Tong , Rothstein Steven J
Published: August 2007

Background

A large quantity of nitrogen (N) fertilizer is used for crop production to achieve high yields at a significant economic and environmental cost. Efforts have been directed to understanding the molecular basis of plant responses to N and identifying N-responsive genes in order to manipulate their expression, thus enabling plants to use N more efficiently. No studies have yet delineated these responses at the transcriptional level when plants are grown under chronic N stress and the understanding of regulatory elements involved in N response is very limited.

Results

To further our understanding of the response of plants to varying N levels, a growth system was developed where N was the growth-limiting factor. An Arabidopsis whole genome microarray was used to evaluate global gene expression under different N conditions. Differentially expressed genes under mild or severe chronic N stress were identified. Mild N stress triggered only a small set of genes significantly different at the transcriptional level, which are largely involved in various stress responses. Plant responses were much more pronounced under severe N stress, involving a large number of genes in many different biological processes. Differentially expressed genes were also identified in response to short- and long-term N availability increases. Putative N regulatory elements were determined along with several previously known motifs involved in the responses to N and carbon availability as well as plant stress.

Conclusion

Differentially expressed genes identified provide additional insights into the coordination of the complex N responses of plants and the components of the N response mechanism. Putative N regulatory elements were identified to reveal possible new components of the regulatory network for plant N responses. A better understanding of the complex regulatory network for plant N responses will help lead to strategies to improve N use efficiency.
Large-scale polymorphism of heterochromatic repeats in the DNA of Arabidopsis thaliana
Authors: Davison Jerry , Tyagi Anand , Comai Luca
Published: August 2007

Background

The composition of the individual eukaryote's genome and its variation within a species remain poorly defined. Even for a sequenced genome such as that of the model plant Arabidopsis thaliana accession Col-0, the large arrays of heterochromatic repeats are incompletely sequenced, with gaps of uncertain size persisting in them.

Results

Using geographically separate populations of A. thaliana, we assayed variation in the heterochromatic repeat arrays using two independent methods and identified significant polymorphism among them, with variation by as much as a factor of two in the centromeric 180 bp repeat, in the 45S rDNA arrays and in the Athila retroelements. In the accession with highest genome size as measured by flow cytometry, Loh-0, we found more than a two-fold increase in 5S RNA gene copies relative to Col-0; results from fluorescence in situ hybridization with 5S probes were consistent with the existence of size polymorphism between Loh-0 and Col-0 at the 5S loci. Comparative genomic hybridization results of Loh-0 and Col-0 did not support contiguous variation in copy number of protein-coding genes on the scale needed to explain their observed genome size difference. We developed a computational data model to test whether the variation we measured in the repeat fractions could account for the different genome sizes determined with flow cytometry, and found that this proposed relationship could account for about 50% of the variance in genome size among the accessions.

Conclusion

Our analyses are consistent with substantial repeat number polymorphism for 5S and 45S ribosomal genes among accession of A. thaliana. Differences are also suggested for centromeric and pericentromeric repeats. Our analysis also points to the difficulties in measuring the repeated fraction of the genome and suggests that independent validation of genome size should be sought in addition to flow cytometric measurements.
A new enzymatic route for production of long 5'-phosphorylated oligonucleotides using suicide cassettes and rolling circle DNA synthesis
Authors: Lohmann Jakob S , Stougaard Magnus , Koch Jørn
Published: August 2007

Background

The quality of chemically synthesized oligonucleotides falls with the length of the oligonucleotide, not least due to depurinations and premature termination during production. This limits the use of long oligonucleotides in assays where long high-quality oligonucleotides are needed (e.g. padlock probes). Another problem with chemically synthesized oligonucleotides is that secondary structures contained within an oligonucleotide reduce the efficiency of HPLC and/or PAGE purification. Additionally, ligation of chemically synthesized oligonucleotides is less efficient than the ligation of enzymatically produced DNA molecules.

Results

Chemically synthesized oligonucleotides with hairpin structures were acquired from our standard supplier. The stem of the hairpin contained recognition sequences for the Nt. Alw I nicking enzyme and the Mly I restriction enzyme. These double stranded regions were positioned in a way to allow self-templated circularization of the oligonucleotide. Following ligation, tandem repeats of the complementary sequence of the circular oligonucleotide could be produced through rolling circle DNA synthesis. By running successive rounds of ligation, rolling circle DNA synthesis, and nicking, the original oligonucleotide could be amplified as either the (+)-strand or the (-)-strand. Alternatively, the hairpin structure could be removed by cleavage with the Mly I restriction enzyme, thereby releasing the oligonucleotide sequence contained within the hairpin structure from the hairpin.

Conclusion

We present here a method for the enzymatic production through DNA amplification of oligonucleotides with freely designable 5'-ends and 3'-ends, using hairpin-containing self-templating oligonucleotides. The hairpin comprises recognition sequences for a nicking enzyme and a restriction enzyme. The oligonucleotides are amplified by successive rounds of ligation, rolling circle DNA synthesis and nicking. Furthermore, the hairpin can be removed by cleavage with the Mly I restriction enzyme. We have named such hairpin structures "suicide cassettes".
Between health care and social security – psychiatric patients and the disability pension system in Norway and Russia
Authors: Rezvyy Grigory , Schönfelder Walter , Øiesvold Terje , Olstad Reidun , Midré Georges
Published: August 2007

Background

The official statistics of persons with mental disorders who are granted disability pension (DP) in Russia and Norway indicate large differences between the countries.

Methods

This qualitative explorative hypothesis-generating study is based on text analysis of the laws, regulations and guidelines, and qualitative interviews of informants representing all the organisational elements of the DP systems in both countries.

Results

The DP application process is initiated much later in Norway than in Russia, where a 3 year occupational rehabilitation and adequate treatment is mandatory before DP is granted. In Russia, two instances are responsible for preparing of the medical certification for DP, a patients medical doctor (PD) and a clinical expert commission (CEC) while there is one in Norway (PD). In Russia, the Bureau of Medical-Social Expertise is responsible for evaluation and granting of DP. In Norway, the local social insurance offices (SIO) are responsible for the DP application. Decisions are taken collectively in Russia, while the Norwegian PD and SIO officer often take decisions alone. In Russia, the medical criterion is the decisive one, while rehabilitation and treatment criteria are given priority in Norway. The size of the DP in Norway is enough to cover of subsistences expenditure, while the Russian DP is less than the level required for minimum subsistence.

Conclusion

There were noteworthy differences in the time frame, organisation model and process leading to a DP in the two countries. These differences may explain why so few patients with less severe mental disorders receive a DP in Russia. This fact, in combination with the size of the DP, may hamper reforms of the mental health care system in Russia.
Comparison of PCR-based detection of Plasmodium falciparum infections based on single and multicopy genes
Authors: Oyedeji Segun I , Awobode Henrietta O , Monday Gamaliel C , Kendjo Eric , Kremsner Peter G , Kun Jürgen F
Published: August 2007

PCR-based assays are the most sensitive and specific methods to detect malaria parasites.

This study compared the diagnostic accuracy of three PCR-based assays that do not only differ in their sequence target, but also in the number of copies of their target region, for the detection of Plasmodium falciparum in 401 individuals living in a malaria-endemic area in Nigeria. Compared to a composite reference generated from results of all the 3 PCR assays, the stevor gene amplification had a sensitivity of 100% (Kappa = 1; 95% CI = 1.000–1.000), 83% (Kappa = 0.718; 95% CI = 0.648–0.788) by SSUrRNA gene PCR and 71% (Kappa = 0.552; 95% CI = 0.478–0.627) by the msa-2 gene amplification.

Results from this study indicate that the stevor gene amplification is the most sensitive technique for the detection of P. falciparum. This assay may be an important reference standard, especially when a confirmatory technique with high sensitivity and specificity is needed for ruling out P. falciparum infection.
Intrafetal Insulin-Like Growth Factor-I Infusion Stimulates Adrenal Growth But Not Steroidogenesis in the Sheep Fetus during Late Gestation
Authors: Ross J. T. , McMillen I. C. , Lok F. , Thiel A. G. , Owens J. A. , Coulter C. L.
Published: August 2007

We investigated the effects of an intrafetal infusion of IGF-I on adrenal growth and expression of the adrenal steroidogenic and catecholamine-synthetic enzyme mRNAs in the sheep fetus during late gestation. Fetal sheep were infused for 10 d with either IGF-I (26 μg/kg·h; n = 14) or saline (n = 10) between 120 and 130 d gestation, and adrenal glands were collected for morphological analysis and determination of the mRNA expression of steroidogenic and catecholamine-synthetic enzymes. Fetal body weight was not altered by IGF-I infusion; however, adrenal weight was significantly increased by 145% after IGF-I infusion. The density of cell nuclei within the fetal adrenal cortex (the zona glomerulosa and zona fasciculata), and within the adrenaline synthesizing zone of the adrenal medulla, was significantly less in the IGF-I-infused fetuses compared with the saline-infused group. Thus, based on cell-density measurements, there was a significant increase in cell size in the zona glomerulosa and zona fasciculata of the adrenal cortex and in the adrenaline-synthesizing zone of the adrenal medulla. There was no effect of IGF-I infusion on the adrenal mRNA expression of the steroidogenic or catecholamine-synthetic enzymes or on fetal plasma cortisol concentrations. In summary, infusion of IGF-I in late gestation resulted in a marked hypertrophy of the steroidogenic and adrenaline-containing cells of the fetal adrenal in the absence of changes in the mRNA levels of adrenal steroidogenic or catecholamine-synthetic enzymes or in fetal plasma cortisol concentrations. Thus, IGF-I infusion results in a dissociation of adrenal growth and function during late gestation.
Pbx homeodomain proteins direct Myod activity to promote fast-muscle differentiation
Authors: Maves Lisa , Waskiewicz Andrew Jan , Paul Biswajit , Cao Yi , Tyler Ashlee , Moens Cecilia B. , Tapscott Stephen J.
Published: August 2007

The basic helix-loop-helix (bHLH) transcription factor Myod directly regulates gene expression throughout the program of skeletal muscle differentiation. It is not known how a Myod-driven myogenic program is modulated to achieve muscle fiber-type-specific gene expression. Pbx homeodomain proteins mark promoters of a subset of Myod target genes,including myogenin (Myog); thus, Pbx proteins might modulate the program of myogenesis driven by Myod. By inhibiting Pbx function in zebrafish embryos, we show that Pbx proteins are required in order for Myod to induce the expression of a subset of muscle genes in the somites. In the absence of Pbx function, expression of myog and of fast-muscle genes is inhibited, whereas slow-muscle gene expression appears normal. By knocking down Pbx or Myod function in combination with another bHLH myogenic factor,Myf5, we show that Pbx is required for Myod to regulate fast-muscle, but not slow-muscle, development. Furthermore, we show that Sonic hedgehog requires Myod in order to induce both fast- and slow-muscle markers but requires Pbx only to induce fast-muscle markers. Our results reveal that Pbx proteins modulate Myod activity to drive fast-muscle gene expression, thus showing that homeodomain proteins can direct bHLH proteins to establish a specific cell-type identity.
Novel mutations affecting axon guidance in zebrafish and a role for plexin signalling in the guidance of trigeminal and facial nerve axons
Authors: Tanaka Hideomi , Maeda Ryu , Shoji Wataru , Wada Hironori , Masai Ichiro , Shiraki Toshiyuki , Kobayashi Megumi , Nakayama Ryoko , Okamoto Hitoshi
Published: August 2007

In zebrafish embryos, the axons of the posterior trigeminal (Vp) and facial(VII) motoneurons project stereotypically to a small number of target muscles derived from the first and second branchial arches (BA1, BA2). Use of the Islet1 (Isl1)-GFP transgenic line enabled precise real-time observations of the growth cone behaviour of the Vp and VII motoneurons within BA1 and BA2. Screening for N-ethyl-N-nitrosourea-induced mutants identified seven distinct mutations affecting different steps in the axonal pathfinding of these motoneurons. The class 1 mutations caused severe defasciculation and abnormal pathfinding in both Vp and VII motor axons before they reached their target muscles in BA1. The class 2 mutations caused impaired axonal outgrowth of the Vp motoneurons at the BA1-BA2 boundary. The class 3 mutation caused impaired axonal outgrowth of the Vp motoneurons within the target muscles derived from BA1 and BA2. The class 4 mutation caused retraction of the Vp motor axons in BA1 and abnormal invasion of the VII motor axons in BA1 beyond the BA1-BA2 boundary. Time-lapse observations of the class 1 mutant, vermicelli (vmc), which has a defect in the plexin A3 (plxna3) gene, revealed that Plxna3 acts with its ligand Sema3a1 for fasciculation and correct target selection of the Vp and VII motor axons after separation from the common pathways shared with the sensory axons in BA1 and BA2, and for the proper exit and outgrowth of the axons of the primary motoneurons from the spinal cord.
GLH-1, theC. elegansP granule protein, is controlled by the JNK KGB-1 and by the COP9 subunit CSN-5
Authors: Orsborn April M. , Li Wensheng , McEwen Tamara J. , Mizuno Tomoaki , Kuzmin Evgeny , Matsumoto Kunihiro , Bennett Karen L.
Published: August 2007

The GLHs (germline RNA helicases) are constitutive components of the germline-specific P granules in the nematode Caenorhabditis elegansand are essential for fertility, yet how GLH proteins are regulated remains unknown. KGB-1 and CSN-5 are both GLH binding partners, previously identified by two-hybrid interactions. KGB-1 is a MAP kinase in the Jun N-terminal kinase(JNK) subfamily, whereas CSN-5 is a subunit of the COP9 signalosome. Intriguingly, although loss of either KGB-1 or CSN-5 results in sterility,their phenotypes are strikingly different. Whereas csn-5 RNA interference (RNAi) results in under-proliferated germlines, similar to glh-1/glh-4(RNAi), the kgb-1(um3) loss-of-function mutant exhibits germline over-proliferation. When kgb-1(um3) mutants are compared with wild-type C. elegans, GLH-1 protein levels are as much as 6-fold elevated and the organization of GLH-1 in P granules is grossly disrupted. A series of additional in vivo and in vitro tests indicates that KGB-1 and CSN-5 regulate GLH-1 levels, with GLH-1 targeted for proteosomal degradation by KGB-1 and stabilized by CSN-5. We propose the `good cop: bad cop' team of CSN-5 and KGB-1 imposes a balance on GLH-1 levels, resulting in germline homeostasis. In addition, both KGB-1 and CSN-5 bind Vasa, a Drosophila germ granule component; therefore, similar regulatory mechanisms might be conserved from worms to flies.
Vesicular traffic at the cell membrane regulates oocyte meiotic arrest
Authors: El-Jouni Wassim , Haun Shirley , Hodeify Rawad , Hosein Walker Azida , Machaca Khaled
Published: August 2007

Vertebrate oocytes are maintained in meiotic arrest for prolonged periods of time before undergoing oocyte maturation in preparation for fertilization. Cyclic AMP (cAMP) signaling plays a crucial role in maintaining meiotic arrest, which is released by a species-specific hormonal signal. Evidence in both frog and mouse argues that meiotic arrest is maintained by a constitutively active G-protein coupled receptor (GPCR) leading to high cAMP levels. Because activated GPCRs are typically targeted for endocytosis as part of the signal desensitization pathway, we were interested in determining the role of trafficking at the cell membrane in maintaining meiotic arrest. Here we show that blocking exocytosis, using a dominant-negative SNAP25 mutant in Xenopus oocytes, releases meiotic arrest independently of progesterone. Oocyte maturation in response to the exocytic block induces the MAPK and Cdc25C signaling cascades, leading to MPF activation, germinal vesicle breakdown and arrest at metaphase of meiosis II with a normal bipolar spindle. It thus replicates all tested aspects of physiological maturation. Furthermore, inhibiting clathrin-mediated endocytosis hinders the effectiveness of progesterone in releasing meiotic arrest. These data show that vesicular traffic at the cell membrane is crucial in maintaining meiotic arrest in vertebrates, and support the argument for active recycling of a constitutively active GPCR at the cell membrane.
Analysis of zebrafishsidetrackedmutants reveals a novel role for Plexin A3 in intraspinal motor axon guidance
Authors: Palaisa Kelly A. , Granato Michael
Published: August 2007

One of the earliest guidance decisions for spinal cord motoneurons occurs when pools of motoneurons orient their growth cones towards a common,segmental exit point. In contrast to later events, remarkably little is known about the molecular mechanisms underlying intraspinal motor axon guidance. In zebrafish sidetracked (set) mutants, motor axons exit from the spinal cord at ectopic positions. By single-cell labeling and time-lapse analysis we show that motoneurons with cell bodies adjacent to the segmental exit point properly exit from the spinal cord, whereas those farther away display pathfinding errors. Misguided growth cones either orient away from the endogenous exit point, extend towards the endogenous exit point but bypass it or exit at non-segmental, ectopic locations. Furthermore, we show that sidetracked acts cell autonomously in motoneurons. Positional cloning reveals that sidetracked encodes Plexin A3, a semaphorin guidance receptor for repulsive guidance. Finally, we show that sidetracked(plexin A3) plays an additional role in motor axonal morphogenesis. Together, our data genetically identify the first guidance receptor required for intraspinal migration of pioneering motor axons and implicate the well-described semaphorin/plexin signaling pathway in this poorly understood process. We propose that axonal repulsion via Plexin A3 is a major driving force for intraspinal motor growth cone guidance.
Variation in Canadian French usage from the 18th to the 19th century
Authors: Martineau France
Published: August 2007

On the basis of private documents (letters, diaries), this article discusses the language use of Canadian French writers from different social classes from the beginning of the 18th century to the end of the 19th century. It first examines the relationship between the writers and the norm and their use of conservative and innovative features with regard to spelling and grammar. Next, it looks into the extent to which non-standard spelling use could be paralleled with vernacular use of morpho-syntactic features.

ne montre pas mon griffonage jan ai honte moi-même

‘Do not show my scribbles, I am ashamed of them’ (18th century)
Writing ability and the written language of Danish private soldiers in the Three Year's War (1848–50)
Authors: Sandersen Vibeke
Published: August 2007

This contribution focuses on letters written by private soldiers from Denmark around the middle of the 19th century. It investigates whether there were statistically significant differences in the orthographic skills between the social groups into which the rural male population could be classified at that time. Apart from the writers' social rank, I look at the correlation between the percentage of norm divergence and the correspondents' place and time of birth, as well as the length of the letter and the repeated use of specific types of divergences by the correspondents.
Differential Response of Adult and Embryonic Mesenchymal Progenitor Cells to Mechanical Compression in Hydrogels
Authors: Terraciano Vanessa , Hwang Nathaniel , Moroni Lorenzo , Park Hyung Bin , Zhang Zijun , Mizrahi Joseph , Seliktar Dror , Elisseeff Jennifer
Published: August 2007

Cells in the musculoskeletal system can respond to mechanical stimuli, supporting tissue homeostasis and remodeling. Recent studies have suggested that mechanical stimulation also influences the differentiation of MSCs, whereas the effect on embryonic cells is still largely unknown. In this study, we evaluated the influence of dynamic mechanical compression on chondrogenesis of bone marrow-derived MSCs and embryonic stem cell-derived (human embryoid body-derived [hEBd]) cells encapsulated in hydrogels and cultured with or without transforming growth factor β-1 (TGF-β1). Cells were cultured in hydrogels for up to 3 weeks and exposed daily to compression for 1, 2, 2.5, and 4 hours in a bioreactor. When MSCs were cultured, mechanical stimulation quantitatively increased gene expression of cartilage-related markers, Sox-9, type II collagen, and aggrecan independently from the presence of TGF-β1. Extracellular matrix secretion into the hydrogels was also enhanced. When hEBd cells were cultured without TGF-β1, mechanical compression inhibited their differentiation as determined by significant downregulation of cartilage-specific genes. However, after initiation of chondrogenic differentiation by administration of TGF-β1, the hEBd cells quantitatively increased expression of cartilage-specific genes when exposed to mechanical compression, similar to the bone marrow-derived MSCs. Therefore, when appropriately directed into the chondrogenic lineage, mechanical stimulation is beneficial for further differentiation of stem cell tissue engineered constructs.

Disclosure of potential conflicts of interest is found at the end of this article.
Errors in Radar CMP Velocity Estimates Due to Survey Geometry, and Their Implication for Ice Water Content Estimation
Authors: Barrett Brian Edward , Murray Tavi , Clark Roger
Published: August 2007

The accuracy of velocity determination from common mid-point (CMP) ground penetrating radar surveys has been assessed in the past and found to be sufficient for migration and depth determination. Increasingly, these velocities are also being used to quantify subsurface physical properties such as water content. This paper demonstrates that small errors in measured velocity can result in large errors in these derived properties. We have evaluated the size of some error sources with specific reference to a given glaciological model and common glaciological survey conditions. At worst, large static errors and 3% errors in measured offset result in interval velocity errors of [Formula: see text]. This error is large enough that derived water content has an error greater than 80% (e.g., [Formula: see text] volumetric % water). Common acquisition and processing practices result in [Formula: see text] interval velocity errors (corresponding to [Formula: see text] error in water content, e.g., [Formula: see text] volumetric %); best practices could result in errors as low as [Formula: see text] in interval velocity (corresponding to [Formula: see text] error in water content, e.g., [Formula: see text] volumetric %), but to achieve this level of precision requires a revision of common practice for CMP acquisition and processing. This revision would need to result in improved assignment of time zero and a consistent definition of reflection event arrival time (to provide travel time errors smaller than 0.5%), and accurate measurement of CMP geometry.