Ideal Tool (ideal + tool)

Distribution by Scientific Domains

Selected Abstracts

MR imaging methods for assessing fetal brain development

Mary Rutherford
Abstract Fetal magnetic resonance imaging provides an ideal tool for investigating growth and development of the brain in vivo. Current imaging methods have been hampered by fetal motion but recent advances in image acquisition can produce high signal to noise, high resolution 3-dimensional datasets suitable for objective quantification by state of the art post acquisition computer programs. Continuing development of imaging techniques will allow a unique insight into the developing brain, more specifically process of cell migration, axonal pathway formation, and cortical maturation. Accurate quantification of these developmental processes in the normal fetus will allow us to identify subtle deviations from normal during the second and third trimester of pregnancy either in the compromised fetus or in infants born prematurely. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008 [source]

Selectivity and competitive interactions between two benthic invertebrate grazers (Asellus aquaticus and Potamopyrgus antipodarum): an experimental study using 13C- and 15N-labelled diatoms

Summary 1. Tracer experiments with two diatoms labelled with 13C (Nitzschia palea) and 15N (Fragilaria crotonensis), were conducted to investigate feeding selectivity and interspecific competition between the grazers Asellus aquaticus (Isopoda, Crustacea) and Potamopyrgus antipodarum (Hydrobiidae, Gastropoda). Conventional methods, such as cell counts and estimated biovolume, were used first to detect feeding preferences within the different grazer treatments. 2. The results revealed a significant decline in algal biovolume in all grazer treatments and no indications of active selectivity were observed. In contrast to conventional methods, measurements based on isotope signatures showed strong differences in tracer uptake, thus indicating different degrees of assimilation and digestion by the two grazers. 3. The selectivity index Q, which provides information on the uptake ratio of 13C to 15N, showed a significant time effect for both grazer species and a significant difference between single- and mixed-grazer treatments for P. antipodarum. Thus, this technique enabled the direct quantification of the uptake by grazers and, therefore, served as an ideal tool for the detection of passive selectivity. 4. Our results indicate a shift in feeding preferences related to between-species competition and a potential divergence of trophic niches when species coexist. [source]

On dichotomizing phenotypes in family-based association tests: quantitative phenotypes are not always the optimal choice

David Fardo
Abstract In family-based association studies, quantitative traits are thought to provide higher statistical power than dichotomous traits. Consequently, it is standard practice to collect quantitative traits and to analyze them as such. However, in many situations, continuous measurements are more difficult to obtain and/or need to be adjusted for other factors/confounding variables which also have to be measured. In such scenarios, it can be advantageous to record and analyze a "simplified/dichotomized" version of the original trait. Under fairly general circumstances, we derive here rules for the dichotomization of quantitative traits that maintain power levels that are comparable to the analysis of the original quantitative trait. Using simulation studies, we show that the proposed rules are robust against phenotypic misclassification, making them an ideal tool for inexpensive phenotyping in large-scale studies. The guidelines are illustrated by an application to an asthma study. Genet. Epidemiol. 2007. © 2007 Wiley-Liss, Inc. [source]

Characterization of the Mucor circinelloides life cycle by on-line image analysis

T.L. Lübbehüsen
Abstract Aims: The life cycle of the dimorphic fungus Mucor circinelloides was studied in a temperature-controlled flow-through cell, which constitutes an ideal tool when following the development of individual cells, with a view to understanding the growth and differentiation processes occurring in and between the different morphological forms of the organism. Methods and Results: Mycelial growth and the transformation of hyphae into chains of arthrospores were characterized by image analysis techniques and described quantitatively. The influence of the nature (glucose and xylose) and concentration of the carbon source on specific growth rate and hyphal growth unit length were studied. The organism branched more profusely on xylose than on glucose while the specific growth rates determined were rather similar. Methods were developed to study the yeast-like growth phase of M. circinelloides in the flow-through cell, and combined with fluorescent microscopy which allowed new insights to bud formation. Additionally, numbers and distribution of nuclei in arthrospores, hyphae and yeasts were studied. Conclusions: The results give essential information on the morphological development of the organism. Significance and Impact of Study: Development of any industrial process utilizing this organism will be dependent on the information obtained here for effective process optimization. [source]

Using terahertz pulsed spectroscopy to quantify pharmaceutical polymorphism and crystallinity

Clare J. Strachan
Abstract Terahertz pulsed spectroscopy (TPS) is a new technique that is capable of eliciting rich information when investigating pharmaceutical materials. In solids, it probes long-range crystalline lattice vibrations and low energy torsion and hydrogen bonding vibrations. These properties make TPS potentially an ideal tool to investigate crystallinity and polymorphism. In this study four drugs with different solid-state properties were analyzed using TPS and levels of polymorphism and crystallinity were quantified. Carbamazepine and enalapril maleate polymorphs, amorphous, and crystalline indomethacin, and thermotropic liquid crystalline and crystalline fenoprofen calcium mixtures were quantified using partial least-squares analysis. Root-mean-squared errors of cross validation as low as 0.349% and limits of detection as low as approximately 1% were obtained, demonstrating that TPS is an analytical technique of potential in quantifying solid-state properties of pharmaceutical compounds. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:837,846, 2005 [source]

The European Nutrigenomics Organisation: linking genomics, nutrition and health research

Siân B Astley
Abstract The science of nutrigenomics allows us to consider not only the response of our genes, proteins and metabolism to diet but also life-stage and lifestyle. Public health messages are failing to change people's behaviour and to counteract the flashy advertising promoting cheap nutritionally-empty foods. Proponents suggest that using the information supplied by nutrigenomics to develop personalised diet and lifestyle regimens would enable consumers to make healthier choices for themselves. For some this will mean accessing new food products and genetic testing but for others it will mean better dietary advice that can be applied in their situation. Opponents argue that this approach merely panders to the worried-wealthy-well , those least in need of intervention because they are already diet and health conscious , and that nutrigenomics fails to address the real issues associated with diet-related disease. Is nutrigenomics another over-hyped science, which will ultimately disappoint, or is it an ideal tool for nutrition research? Copyright © 2007 Society of Chemical Industry [source]

Twin-screw extrusion of polypropylene-clay nanocomposites: Influence of masterbatch processing, screw rotation mode, and sequence

Mark A. Treece
This work seeks to optimize the twin-screw compounding of polymer-clay nanocomposites (PCNs). Proportional amounts (3:1) of maleic anhydride functionalized polypropylene compatibilizer (PP- g -MA) and organically modified montmorillonite clay at clay loadings of 1, 3, and 5 wt% were melt-blended with a polypropylene (PP) homopolymer using a Leistritz Micro 27 twin-screw extruder. Three melt-blending approaches were pursued: (1) a masterbatch of PP- g -MA and organoclay were blended in one pass followed by dilution with the PP resin in a second pass; (2) all three components were processed in a single pass; and (3) uncompatibilized PP and organoclay were processed twice. Both corotation and counterrotation operation were utilized to investigate the effect of screw rotation mode and sequence on organoclay exfoliation and dispersion. X-ray diffraction was employed to characterize basal spacing; however, since rheology is known to be highly sensitive to mesoscale organoclay structure, it is an ideal tool to examine the relationship between the various processing methods and exfoliation and dispersion. A holistic analysis of rheological data demonstrates the efficacy of the masterbatch approach, particularly when compatibilizer and organoclay are blended in counterrotating mode followed by dilution with matrix polymer in corotating mode. POLYM. ENG. SCI., 47:898,911, 2007. © 2007 Society of Plastics Engineers [source]

Computer Algebra Algorithms for Control Related Tests of Implicit Dynamic Systems

Kurt Schlacher
This contribution is focused on control related tests for implicit dynamic systems, like accessibility, observability or input to output, input to state linearizability. Since the performance of these tests needs tedious symbolic calculations, computer algebra systems are the ideal tool to cope with this problem. Accessibility and observability are exemplarily used to present a new approach based on Lie groups. It is shown that non accessible or non observable systems admit Lie-groups acting on their solutions such that distinguished parts remain unchanged. This fact allows us to apply this technique, as well as its realization by computer algebra algorithm, to several fundamental problems in control. [source]

Pancreatic solid pseudopapillary tumours , EUS FNA is the ideal tool for diagnosis

Alina Stoita
Abstract Background:, Solid pseudopapillary tumour (SPT) is a rare tumour of the pancreas with low malignant potential affecting mainly young women difficult to diagnose preoperatively. The aim of this study is to describe the endoscopic ultrasound (EUS) features and utility of EUS-guided fine needle aspiration (FNA) in diagnosing these tumours. Methods:, A retrospective analysis of SPTs identified in a tertiary institution EUS database between April 2002 and April 2009 was performed. Medical records, imaging, EUS features, cytology and histology specimens were reviewed. Patients were followed up until April 2009. Results:, Seven cases of SPTs were indentified out of 2400 EUS performed. All patients were females with a mean age of 41 years (range 22,69). The tumours were solitary with a mean diameter of 2.9 cm (range 2,4.3 cm). Five tumours were located in the body and tail of the pancreas and two in the neck. All lesions were hypoechoic, heterogenous and well circumscribed, with five having a cystic component and two having a calcified rim. FNA using a 22-gauge needle was performed in six cases with no complications. A preoperative diagnosis of SPT based on cytology was obtained in 5/6 cases (83%). Surgical resection was done in six cases with confirmation of SPT and no metastatic disease. Conclusion:, EUS-guided FNA is a minimally invasive, safe and reliable way of diagnosing SPT by providing characteristic cytological specimens. Definitive preoperative diagnosis leads to targeted and minimally invasive surgical resection. [source]


ARCHAEOMETRY, Issue 3 2010
Many important cultural and religious objects from Asia consist of outer metallic shapes, usually bronze, which fully enclose inner contents made of organic materials such as wood, bark, paper, textile, plants and others. Bronze and other metallic materials, such as copper and silver, are generally more transparent to neutrons than to X-rays. However, organic materials are less transparent to neutrons than to X-rays and therefore organic materials, enclosed by metallic materials, can be made visible with neutrons. Therefore, neutron imaging (radiography and tomography) was found to be an ideal tool for the inspection of objects that consist of metal outside and organic materials inside. This has been successfully demonstrated here with four metallic Tibetan Buddha statues, providing archaeometry with a powerful new tool. The first successful applications of this novel technique are described in this article. Further possible and useful applications of neutron imaging of cultural objects are outlined. [source]

The lack of significant changes in scalp hair follicle density with advancing age

R. Sinclair
Summary Background, Age-related reduction in hair is seen in the axillary and pubic regions as well as the scalp; however, it has not been investigated qualitatively on the scalp. Horizontally sectioned scalp biopsy is an ideal tool to investigate the impact of advancing age on scalp hair follicle density and morphology. Objectives, To examine the effect of age and follicle miniaturization on total hair count in 1666 horizontally sectioned mid-scalp biopsies from 928 women aged between 13 and 84 years with hair loss. Methods Setting:, Specialist hair loss referral clinic in a teaching hospital. Design: Analysis of data set. Methods:, All scalp biopsies were 4 mm in diameter and taken from the crown. Miniaturization was assessed by calculating the ratio of terminal to vellus-like hairs (T/V) at the mid-isthmus level and considered significant if the ratio was , 4 : 1. Fibrosis was documented when present. Linear regression was used to examine the association between total hair count, age and miniaturization. Results, The average number of hair follicles per biopsy was 39·6 (SD ± 10·8). A highly significant negative association (P < 0·0001) was found between age and total follicle number, although the predictive value of age in total hair count was found to be small [root error mean square (R2) < 2%]. Controlling for T/V , 4 : 1, the association was weakened, but remained significant. The relationship unconfounded by T/V , 4 : 1 shows that for every additional year of ageing, 0·077 total hair follicles (0·22%) are lost per biopsy. Conclusions, Age and follicular miniaturization were found to be extremely weak predictors of total hair count in women with hair loss. [source]

Probing the Anisotropic Field-Effect Mobility of Solution-Deposited Dicyclohexyl-,-quaterthiophene Single Crystals,


Abstract Measuring the anisotropy of the field-effect mobility provides insight into the correlation between molecular packing and charge transport in organic semiconductor materials. Single-crystal field-effect transistors are ideal tools to study intrinsic charge transport because of their high crystalline order and chemical purity. The anisotropy of the field effect mobility in organic single crystals has previously been studied by lamination of macroscopically large single crystals onto device substrates. Here, a technique is presented that allows probing of the mobility anisotropy even though only small crystals are available. Crystals of a soluble oligothiophene derivative are grown in bromobenzene and drop-cast onto substrates containing arrays of bottom-contact gold electrodes. Mobility anisotropy curves are recorded by measuring numerous single crystal transistor devices. Surprisingly, two mobility maxima occur at azimuths corresponding to both axes of the rectangular cyclohexyl-substituted quaterthiophene (CH4T) in-plane unit cell, in contrast to the expected tensorial behavior of the field effect mobility. [source]

Evaluating the suitability of nicotinic acetylcholine receptor antibodies for standard immunodetection procedures

N. Moser
Abstract Nicotinic acetylcholine receptors play important roles in numerous cognitive processes as well as in several debilitating central nervous system (CNS) disorders. In order to fully elucidate the diverse roles of nicotinic acetylcholine receptors in CNS function and dysfunction, a detailed knowledge of their cellular and subcellular localizations is essential. To date, methods to precisely localize nicotinic acetylcholine receptors in the CNS have predominantly relied on the use of anti-receptor subunit antibodies. Although data obtained by immunohistology and immunoblotting are generally in accordance with ligand binding studies, some discrepancies remain, in particular with electrophysiological findings. In this context, nicotinic acetylcholine receptor subunit-deficient mice should be ideal tools for testing the specificity of subunit-directed antibodies. Here, we used standard protocols for immunohistochemistry and western blotting to examine the antibodies raised against the ,3-, ,4-, ,7-, ,2-, and ,4-nicotinic acetylcholine receptor subunits on brain tissues of the respective knock-out mice. Unexpectedly, for each of the antibodies tested, immunoreactivity was the same in wild-type and knock-out mice. These data imply that, under commonly used conditions, these antibodies are not suited for immunolocalization. Thus, particular caution should be exerted with regards to the experimental approach used to visualize nicotinic acetylcholine receptors in the brain. [source]

Mass and lifetime measurements of exotic nuclei in storage rings

Bernhard Franzke
Abstract Mass and lifetime measurements lead to the discovery and understanding of basic properties of matter. The isotopic nature of the chemical elements, nuclear binding, and the location and strength of nuclear shells are the most outstanding examples leading to the development of the first nuclear models. More recent are the discoveries of new structures of nuclides far from the valley of stability. A new generation of direct mass measurements which allows the exploration of extended areas of the nuclear mass surface with high accuracy has been opened up with the combination of the Experimental Storage Ring ESR and the FRragment Separator FRS at GSI Darmstadt. In-flight separated nuclei are stored in the ring. Their masses are directly determined from the revolution frequency. Dependent on the half-life two complementary methods are applied. Schottky Mass Spectrometry SMS relies on the measurement of the revolution frequency of electron cooled stored ions. The cooling time determines the lower half-life limit to the order of seconds. For Isochronous Mass Spectrometry IMS the ring is operated in an isochronous ion-optical mode. The revolution frequency of the individual ions coasting in the ring is measured using a time-of-flight method. Nuclides with lifetimes down to microseconds become accessible. With SMS masses of several hundreds nuclides have been measured simultaneously with an accuracy in the 2,×,10,7 -range. This high accuracy and the ability to study large areas of the mass surface are ideal tools to discover new nuclear structure properties and to guide improvements for theoretical mass models. In addition, nuclear half-lives of stored bare and highly charged ions have been measured. This new experimental development is a significant progress since nuclear decay characteristics are mostly known for neutral atoms. For bare and highly charged ions new nuclear decay modes become possible, such as bound-state beta decay. Dramatic changes in the nuclear lifetime have been observed in highly charged ions compared to neutral atoms due to blocking of nuclear decay channels caused by the modified atomic interaction. High ionization degrees prevail in hot stellar matter and thus these experiments have great relevance for the understanding of the synthesis of elements in the universe and astrophysical scenarios in general. © 2008 Wiley Periodicals, Inc., Mass Spec Rev 27: 428,469, 2008 [source]

Applicability of Carbazole Migration Indices in Continental Rift Basins: A Case Study of Western Lujiapu Depression in Kailu Basin, NE China

Shuqing ZHOU
Abstract: Kailu Basin in which the Western Lujiapu Depression is located is a typical continental rift basin. Biomarker parameters of the oils indicate that depositional facies and environments vary between the Bao 1 and Bao 14 fault blocks with a higher saline environment in the Bao 1 fault block, but such difference has no significant impact on carbazole abundance and distribution. Maturity and migration distance are the main controls on carbazole abundance and distribution in the Western Lujiapu Depression. The commonly used migration indices, such as ratios of nitrogen shield isomers to nitrogen exposed isomers (1-/4-methylcarbazole ratio, 1,8-/2,4-dimethylcarbazole (DMC) ratio and half-shield/exposed-DMC ratio), absolute concentrations of alkylated carbazoles and BC ratio (= benzo [a]carbazole/ (benzo[a]carbazole + benzo[c]carbazole)) increase at the low mature range and decrease at a higher mature range with increasing maturity. At relatively low maturity stage (Rc<0.77%), maturation has reversal effects with migration on the ratios of nitrogen shield isomers to nitrogen exposed isomers, which may cover migration influence and makes these parameters fail to indicate migration effects. Valid migration indicators at this maturity stage are concentrations of alkylated carbazoles and BC ratios, which can provide ideal tools for migration direction assessment even within short migration distance. Maturity effects should be taken into account when carbazole compounds are applied to indicate migration direction, and at different maturity stages, these commonly used parameters have different validity in tracing migration direction. Coupled with our previous study in the Eastern Lujiapu Depression, a conceptual model of the variation of nitrogen migration indices can be established for terrestrial rifted basins, that is, strong fractionation lateral migration model through sandy beds, weak fractionation vertical migration model along faults, and maturity impacts on migration assessment. [source]

Patterns of variation at a mitochondrial sequence-tagged-site locus provides new insights into the postglacial history of European Pinus sylvestris populations

N. Soranzo
Abstract Due to their maternal mode of inheritance, mitochondrial markers can be regarded as almost ,ideal' tools in evolutionary studies of conifer populations. In the present study, polymorphism was analysed at one mitochondrial intron (nad 1, exon B/C) in 23 native European Pinus sylvestris populations. In a preliminary screening for variation using a polymerase chain reaction,restriction fragment length polymorphism approach, two length variants were identified. By fully sequencing the 2.5 kb region, the observed length polymorphism was found to result from the insertion of a 31 bp sequence, with no other mutations observed within the intron. A set of primers was designed flanking the observed mutation, which identified a novel sequence-tagged-site mitochondrial marker for P. sylvestris. Analysis of 747 trees from the 23 populations using these primers revealed the occurrence of two distinct haplotypes in Europe. Within the Iberian Peninsula, the two haplotypes exhibited extensive population differentiation (,ST = 0.59; P , 0.001) and a marked geographical structuring. In the populations of central and northern Europe, one haplotype largely predominated, with the second being found in only one individual of one population. [source]