bluuebunny/crossref_metadata_2025 huggingface dataset:
Inviscid compressible flow with shock in two-dimensional slender nozzles
Authors: Lin C. Q. , Shen S. F.
Published: April 2006

The present theory provides an asymptotic-expansion method for inviscid compressible flows with shock in arbitrary two-dimensional slender nozzles. The flow in front of the shock is assumed to be potential, whereas the flow behind the shock is considered to be rotational owing to the presence of the shock. A parameter that measures the slenderness of the nozzle is used as the expansion quantity. It is found that, except for the region immediately behind the shock, the same coordinate scale can be used for the flows both in front of and further downstream behind the shock. The flows for the regions thus obtained show that all the streamlines are approximately affinely similar to the nozzle wall, and the leading term of the transverse pressure gradient is determined by the local wall shape. For the flow region immediately behind the shock, however, the transverse pressure gradient just behind the shock is determined by the shock conditions rather than by the local wall shape, and a solution is found for that region which transforms the transverse pressure gradient from that determined by the shock conditions to that determined by the local wall shape. The well-known flow singularity at the intersection of the wall and the shock is involved in the solution. Meanwhile, a critical shock location at which the flow has no singularity is derived. A numerical example shows also that the inviscid flow may separate from the wall, owing to the different entropy increase across the shock for different streamlines. The predicted separation point, however, is only of qualitative value, since our theory does not account for reverse flows.
An analysis of near-marginal, mildly penetrative convection with heat flux prescribed on the boundaries
Authors: Roberts A. J.
Published: April 2006

The model penetrative-convection problem of ice–water convection is considered. Analytical progress is made through the remarkable simplification that horizontally long convection cells are preferred when the heat flux is fixed on the boundaries (Chapman & Proctor 1980). However, a linear analysis shows that long horizontal scales are preferred only when the convection is mildly penetrative (i.e. the overlying layer of stable fluid is not deep). A straightforward nonlinear asymptotic analysis of the convection only provides the relatively uninteresting information that the convection is subcritical. Using the technique of reconstitution (Roberts 1985) to provide higher-order corrections to the asymptotic theory, flow properties at larger amplitudes are calculated and predictions about the extent of the subcriticality are made.
Analysis of chemical effects on reflected-shock flow fields in combustible gas
Authors: Takano Yasunari , Akamatsu Teruaki
Published: April 2006

This paper analyses effects of chemical reactions on reflected-shock flow fields in shock tubes. The method of linearized characteristics is applied to analyse gasdynamic disturbances due to chemical reactions. The analysis treats cases where combustible gas is highly diluted in inert gas, and assumes that flows are one-dimensional and that upstream flows in front of the reflected-shock waves are in the frozen state. The perturbed gasdynamic properties in the reflected-shock flow fields are shown to be expressible mainly in terms of a heat-release function for combustion process. In particular, simple relations are obtained between the heat-release function and the physical properties at the end wall of a shock tube. As numerical examples of the analysis, the present formulation is applied to calculate gasdynamic properties in the reflected-shock region in a H2–O2–Ar mixture. Procedures are demonstrated for calculation of the heat-release function by numerically integrating rate equations for chemical species. The analytical results are compared with rigorous solutions obtained numerically by use of a finite-difference method. It is shown that the formulation can afford exact solutions in cases where chemical behaviours are not essentially affected by gasdynamic behaviours. When the induction time of the combustion process is reduced to some extent owing to gasdynamic disturbances, some discrepancies appear between analytical results and rigorous solutions. An estimate is made of the induction-time reduction, and a condition is written down for applicability of the analysis.
Coherence measurements in synthetic turbulent boundary layers
Authors: Savas Ömer , Coles Donald
Published: April 2006

Synthetic turbulent boundary layers were constructed on a flat plate by generating systematic moving patterns of turbulent spots in a laminar flow. The experiments were carried out in a wind tunnel at a Reynolds number based on plate length of 1.7 × 106. Spots were generated periodically in space and time near the leading edge to form a regular hexagonal pattern. The disturbance mechanism was a camshaft that displaced small pins momentarily into the laminar flow at frequencies up to 80 Hz. The main instrumentation was a rake of 24 single hot wires placed across the flow in a line parallel to the surface. The main measured variable was local intermittency; i.e. the probability of observing turbulent flow at a particular point in space and time. The results are reported in numerous (x, z, t)-diagrams showing the evolution of various synthetic flows along the plate. The dimensionless celerity or phase velocity of the large eddies was found to be very nearly 0.88, independent of eddy scale. All patterns with sufficiently small scales eventually showed loss of coherence as they moved downstream. A novel phenomenon called eddy transposition was observed in several flows that contained appreciable laminar regions. The original large eddies were replaced by new eddies at new positions, intermediate to the original ones, while preserving the hexagonal pattern. The present results, together with some empirical properties of a turbulent spot, were used to estimate the best choice of scales for constructing a synthetic boundary layer suitable for detailed study as a model for a natural flow. The values recommended are: spanwise period/thickness ≈ 2.5, streamwise period/thickness ≈ 8.0.
Antibiotic resistance of retail food and human Campylobacter isolates on the island of Ireland from 2001–2002
Authors: McGILL K. , COWLEY D. , MORAN L. , SCATES P. , O'LEARY A. , MADDEN R. H. , CARROLL C. , McNAMARA E. , MOORE J. E. , FANNING S. , COLLINS J. D. , WHYTE P.
Published: April 2006

The antimicrobial resistance profiles of Campylobacter isolates recovered from a range of retail food samples (n=374) and humans (n=314) to eight antimicrobial compounds were investigated. High levels of resistance in food C. jejuni isolates were observed for ceftiofur (58%), ampicillin (25%) and nalidixic acid (17%) with lower levels observed for streptomycin (7·9%) and chloramphenicol (8·3%). A total of 80% of human C. jejuni isolates were resistant to ceftiofur, while 17% showed resistance to ampicillin and nalidixic acid, 8·6% to streptomycin and 4·1% to chloramphenicol. Resistance to clinically relevant antimicrobials such as erythromycin, ciprofloxacin and tetracycline was 6·7, 12, and 15% respectively for all food isolates and was similar to corresponding resistance prevalences observed for human isolates, where 6·4, 12 and 13% respectively were found to be resistant. Comparisons of C. jejuni isolates in each location showed a high degree of similarity although some regional variations did exist. Comparison of total C. jejuni and C. coli populations showed minor differences, with C. jejuni isolates more resistant to ampicillin and ceftiofur. Multidrug resistance patterns showed some profiles common to human and clinical isolates.
Dust events in Kanpur, northern India: Chemical evidence for source and implications to radiative forcing
Authors: Chinnam N. , Dey Sagnik , Tripathi S. N. , Sharma M.
Published: April 2006

Dust samples were collected and analyzed during May 2004 in Kanpur (in Ganga basin), Northern India for the first time. Chemical evidence along with the air mass trajectories suggests three major sources of the mineral dusts transported to the Ganga basin. High concentration of Pb and Cd indicates possible mixing with the anthropogenic pollution. The composite aerosol model reveals low single scattering albedo (∼0.74) due to the presence of black carbon. During the dust storms, shortwave (SW) clear‐sky diurnally averaged top of the atmosphere (TOA) and surface forcing come out to be +11 ± 0.7 and −26 ± 3 W m−2, respectively. Corresponding forcings in the longwave (LW) region are +1.9 ± 0.6 and +1.6 ± 0.4 W m−2. Net atmospheric forcing (i.e., SW+LW, 36 W m−2) corresponds to heating rate of ∼1.02° K/day in the lower atmosphere. Dust alone has resulted in the net TOA and surface forcings of +7 and −12 W m−2.
Low-energy electron stimulated desorption of neutrals from multilayers of SiCl4 on Si(111)
Authors: Lane Christopher D. , Orlando Thomas M.
Published: April 2006

The interaction of low-energy electrons with multilayers of SiCl4 adsorbed on Si(111) leads to production and desorption of Cl(P3∕22), Cl(P1∕22), Si, and SiCl. Resonant structure in the yield versus incident electron energy (Ei) between 6 and 12eV was seen in all neutral channels and assigned to dissociative electron attachment (DEA), unimolecular decay of excited products produced via autodetachment and direct dissociation. These processes yield Cl(P3∕22) and Cl(P1∕22) with nonthermal kinetic energies of 425 and 608meV, respectively. The Cl(P1∕22) is produced solely at the vacuum surface interface, whereas the formation of Cl(P3∕22) likely involves subsurface dissociation, off-normal trajectories, and collisions with neighbors. Structure in the Cl(P3∕22) yield near 14 and 25eV can originate from excitation of electrons in the 2e, 7t2 and 6t2, 6a1 levels, respectively. Although the 14eV feature was not present in the Cl(P1∕22) yield, the broad 25eV feature, which involves complex Auger filling of holes in the 6t2 and 6a1 levels of SiCl4, is observed. Direct ionization, exciton decay, and DEA from secondary electron scattering all occur at Ei>14eV. Si and SiCl were detected via nonresonant ionization of SiClx precursors that are produced via the same states and mechanisms that yield Cl. The Si retains the kinetic energy profile of the desorbed precursors.
Two distinct dielectric relaxation mechanisms in the low-frequency range in Bi5TiNbWO15 ceramics
Authors: Yi Z. G. , Li Y. X. , Wang Y. , Yin Q. R.
Published: April 2006

The ac data in terms of impedance and dielectric loss (tanδ) were exploited simultaneously to probe the dielectric relaxation mechanisms in Bi5TiNbWO15 ceramics. It was found that two distinct relaxation mechanisms exist in the low-frequency range (10Hz–5MHz). One is attributed to the grain boundary relaxation and the other is associated with oxygen ion diffusion. Furthermore, the temperature dependence of the oxygen vacancy relaxation strength is analogous to the Curie-Weiss law and follows the traditional point defect relaxation theory. These results could be helpful to understand the phenomena related to ferroelectric fatigue, oxygen ion conductivity, etc.
Process stabilization and increase of the deposition rate in reactive sputtering of metal oxides and oxynitrides
Authors: Severin D. , Kappertz O. , Kubart T. , Nyberg T. , Berg S. , Pflug A. , Siemers M. , Wuttig M.
Published: April 2006

Reactive sputtering processes normally exhibit undesirable hysteresis effects which are more pronounced for oxide than nitride deposition. We present a method to reduce and ultimately eliminate these effects for reactive sputtering of metal oxides and oxynitrides. This is achieved by the addition of nitrogen to the oxygen process, which in addition leads to a higher deposition rate. These observations can be qualitatively explained and theoretically predicted using an extension of the Berg's model to two different reactive gases. Although the nitrogen addition leads to pronounced changes of the processing characteristics, incorporation of nitrogen into the growing film is very small.
Isotropic left handed material at optical frequency with dielectric spheres embedded in negative permittivity medium
Authors: Seo Byoung-Joon , Ueda Tetsuya , Itoh Tatsuo , Fetterman Harold
Published: April 2006

A possibility to realize an isotropic left handed material up to optical frequencies is theoretically investigated. The proposed homogeneous structure consists of dielectric spheres embedded randomly in a negative permittivity host medium. While the effective permittivity of the structure is negative over a wide frequency range due to the host medium, the negative effective permeability is obtained by spherical magnetic resonances of the dielectric spheres. Since this structure utilizes only magnetic resonance, both analytical and numerical simulation results show that it has higher fabrication tolerance, larger bandwidth and potentially less propagation loss than the previously proposed structure, i.e., the dielectric spheres embedded in the dielectric host.
Seed layer control for tilted magnetic recording media
Authors: Klemmer T. J. , Pelhos K.
Published: April 2006

Theoretical predictions have suggested that tilted magnetic recording may be a way to push recording densities higher than longitudinal and perpendicular recording schemes. However, a method of fabricating such a magnetic recording media has been lacking. In this letter we show that tilted magnetocrystalline anisotropy can be induced in a magnetic layer by using seed layers that were deposited by oblique physical vapor deposition while the magnetic layer is deposited normally. If thermally stable smaller grains, control of exchange, and decreased dispersions can be further realized then this type of fabrication can help realized achieve the predicted potential of tilted media.
Muc4–ErbB2 Complex Formation and Signaling in Polarized CACO-2 Epithelial Cells Indicate That Muc4 Acts as an Unorthodox Ligand for ErbB2
Authors: Ramsauer Victoria P. , Pino Vanessa , Farooq Amjad , Carothers Carraway Coralie A. , Salas Pedro J.I. , Carraway Kermit L.
Published: April 2006

Muc4 serves as an intramembrane ligand for the receptor tyrosine kinase ErbB2. The time to complex formation and the stoichiometry of the complex were determined to be <15 min and 1:1 by analyses of Muc4 and ErbB2 coexpressed in insect cells and A375 tumor cells. In polarized CACO-2 cells, Muc4 expression causes relocalization of ErbB2, but not its heterodimerization partner ErbB3, to the apical cell surface, effectively segregating the two receptors. The apically located ErbB2 is phosphorylated on tyrosines 1139 and 1248. The phosphorylated ErbB2 in CACO-2 cells recruits the cytoplasmic adaptor protein Grb2, consistent with previous studies showing phosphotyrosine 1139 to be a Grb2 binding site. To address the issue of downstream signaling from apical ErbB2, we analyzed the three MAPK pathways of mammalian cells, Erk, p38, and JNK. Consistent with the more differentiated phenotype of the CACO-2 cells, p38 phosphorylation was robustly increased by Muc4 expression, with a consequent activation of Akt. In contrast, Erk and JNK phosphorylation was not changed. The ability of Muc4 to segregate ErbB2 and other ErbB receptors and to alter downstream signaling cascades in polarized epithelial cells suggests that it has a role in regulating ErbB2 in differentiated epithelia.
Phylogenetic placement of Hanseniaspora–Kloeckera species using multigene sequence analysis with taxonomic implications: descriptions of Hanseniaspora pseudoguilliermondii sp. nov. and Hanseniaspora occidentalis var. citrica var. nov.
Authors: Cadez Neza , Raspor Peter , Smith Maudy Th.
Published: April 2006

Two protein-coding genes, actin and translation elongation factor-1α (EF-1α), as well as two ribosomal gene regions, D1/D2 domains of the large subunit and both internal transcribed spacers including the 5.8S gene region, were evaluated regarding their usefulness for reconstruction of phylogenetic relationships in the Hanseniaspora–Kloeckera species group. This included analyses of sequence divergence values, heterogeneity of evolutionary rates and the reliability of the inferred trees. Both protein-coding genes showed greater capacities to resolve at the strain level and between the closely related species of Hanseniaspora–Kloeckera, compared with the ribosomal gene regions. However, to obtain a fully resolved and reliable phylogenetic tree that reflected the biological relationships it was necessary to combine three congruent sequence datasets. The novel species Hanseniaspora pseudoguilliermondii sp. nov. (type strain CBS 8772T) is described as a result of the application of various molecular approaches to delimit species. Furthermore, incongruent gene genealogies of genetically divergent strains of Hanseniaspora occidentalis, as determined by amplified fragment length polymorphism analysis and DNA–DNA reassociation measurements, indicated the presence of two novel varieties, H. occidentalis var. occidentalis (type strain CBS 2592T) and H. occidentalis var. citrica var. nov. (type strain CBS 6783T), which could be distinguished by habitat preference.
Genetic relatedness within the genus Campylobacter inferred from rpoB sequences
Authors: Korczak Bożena M. , Stieber Regina , Emler Stefan , Burnens André P. , Frey Joachim , Kuhnert Peter
Published: April 2006

The genus Campylobacter comprises 17 species, some of which are important animal and human pathogens. To gain more insight into the genetic relatedness of this genus and to improve the molecular tools available for diagnosis, a universal sequencing approach was established for the gene encoding the beta-subunit of RNA polymerase (rpoB) for the genus Campylobacter. A total of 59 strains, including the type strains of currently recognized species as well as field isolates, were investigated in the study. A primer set specific for Campylobacter species enabled straightforward amplification and sequencing of a 530 bp fragment of the rpoB gene. The 16S rRNA gene sequences of all of the strains were determined in parallel. A good congruence was obtained between 16S rRNA and rpoB gene sequence-based trees within the genus Campylobacter. The branching of the rpoB tree was similar to that of the 16S rRNA gene tree, even though a few discrepancies were observed for certain species. The resolution of the rpoB gene within the genus Campylobacter was generally much higher than that of the 16S rRNA gene sequence, resulting in a clear separation of most species and even some subspecies. The universally applicable amplification and sequencing approach for partial rpoB gene sequence determination provides a powerful tool for DNA sequence-based discrimination of Campylobacter species.
A new subclade of haplontic Metschnikowia species associated with insects of morning glory flowers in Africa and description of Metschnikowia aberdeeniae sp. nov.
Authors: Lachance Marc-André , Anderson T. Michael , Starmer William T.
Published: April 2006

The novel species Metschnikowia aberdeeniae is described to accommodate five isolates recovered from insects of morning glory flowers in the Serengeti National Park, Tanzania. On the basis of rDNA ITS and D1/D2 large-subunit sequences, these yeasts form, together with six other isolates, a novel subclade of large-spored Metschnikowia species. The exact position of the subclade within the Metschnikowiaceae cannot be determined with any confidence from these sequences or from small-subunit rDNA sequences, as the variable sites of the sequences are excessively divergent. However, in morphological and physiological terms, the novel isolates are typical of the genus Metschnikowia in general and of the large-spored group in particular. The type strain of Metschnikowia aberdeeniae sp. nov. is strain SUB 05-213.1T (=CBS 10289T=NRRL Y-27921T) (h−) and the allotype is strain SUB 05-213.2 (=CBS 10290=NRRL Y-27922) (h+).
Survival consequences of sex‐biased growth and the absence of a growth–mortality trade‐off
Authors: HUTCHINGS J. A.
Published: April 2006

Growth rate is of considerable importance to the life histories of indeterminately growing organisms. Its determination of size at age can generate positive associations with several traits, although the rate at which size increases with time has been negatively linked with survival. Such a trade‐off may not, however, be evident at growth rates considerably less than species‐specific maxima, nor need links between growth and life history be similar for both sexes.

Based on a 5‐year, mark–recapture study of an unexploited population of Brook Trout (Salvelinus fontinalis) near the edge of the species’ range, I tested the null hypotheses that seasonal growth does not differ between sexes and that survival is independent of growth rate. Both hypotheses were rejected.

Faster growth by males during summer, and by females during winter, can be explained by seasonal differences, by sex, in the proportional allocation of energy to gonads and soma.

Survival increased with growth rate per se, independently of the latter's effects on size at age; survival among males appears more dependent on growth than that of females.

The results indicate that there can be fitness costs associated with slow growth, that these costs can differ between sexes, and that they may be exacerbated during periods of energetic stress. Trade‐offs between growth and survival may depend on the behavioural and developmental contexts in which they are examined, need not be ubiquitous and may vary throughout a species’ geographical range.
Rapid root closure after fire limits fine root responses to elevated atmospheric CO2 in a scrub oak ecosystem in central Florida, USA
Authors: DAY FRANK P. , STOVER DANIEL B. , PAGEL ALISHA L. , HUNGATE BRUCE A. , DILUSTRO JOHN J. , HERBERT BRANDON T. , DRAKE BERT G. , HINKLE CHARLES R.
Published: April 2006

Elevated atmospheric carbon dioxide (CO2) often stimulates the growth of fine roots, yet there are few reports of responses of intact root systems to long‐term CO2 exposure. We investigated the effects of elevated CO2 on fine root growth using open top chambers in a scrub oak ecosystem at Kennedy Space Center, Florida for more than 7 years. CO2 enrichment began immediately after a controlled burn, which simulated the natural disturbance that occurs in this system every 10–15 years. We hypothesized that (1) root abundance would increase in both treatments as the system recovered from fire; (2) elevated CO2 would stimulate root growth; and (3) elevated CO2 would alter root distribution. Minirhizotron tubes were used to measure fine root length density (mm cm−2) every three months. During the first 2 years after fire recovery, fine root abundance increased in all treatments and elevated CO2 significantly enhanced root abundance, causing a maximum stimulation of 181% after 20 months. The CO2 stimulation was initially more pronounced in the top 10 cm and 38–49 cm below the soil surface. However, these responses completely disappeared during the third year of experimental treatment: elevated CO2 had no effect on root abundance or on the depth distribution of fine roots during years 3–7. The results suggest that, within a few years following fire, fine roots in this scrub oak ecosystem reach closure, defined here as a dynamic equilibrium between production and mortality. These results further suggest that elevated CO2 hastens root closure but does not affect maximum root abundance. Limitation of fine root growth by belowground resources – particularly nutrients in this nutrient‐poor soil – may explain the transient response to elevated CO2.
Prognostic and predictive factors in endocrine tumours
Authors: Stephenson T J
Published: April 2006

This review encompasses the diagnostic features of malignancy, the routinely observable prognostic features and the prognostic and predictive features emerging from research techniques in the principal endocrine neoplasms: pancreatic and extrapancreatic endocrine cell tumours, thyroid and parathyroid neoplasia, adrenal cortical neoplasms and adrenal and extra‐adrenal paragangliomas. While each endocrine tissue has its own set of diagnostic features for malignancy, and prognostic features once a diagnosis of malignancy has been established, there are a few common themes. For several endocrine neoplasms, definite recognition of malignancy can be difficult and may depend upon frank invasive or metastatic growth at presentation. Endocrine tissues are dynamic, with hyperplastic and regressive phenomena, some of which may mimic malignancy. Even when unequivocal features of malignancy are available for observation, their distribution in tissue may be very focal, necessitating thorough sampling. The accurate documentation of routinely observable histological features interpreted in the light of current literature has not been superseded by special techniques in the statement of diagnosis or prognosis in the vast majority of endocrine neoplasms.
Long‐term prognosis in patients with bifascicular block – the predictive value of noninvasive and invasive assessment
Authors: TABRIZI F. , ROSENQVIST M. , BERGFELDT L. , ENGLUND A.
Published: April 2006

Objectives.  Patients with bifascicular block (BFB) have a high mortality rate. The purpose of the present study was to identify high‐risk patients in a BFB population by performing an extensive cardiac evaluation including noninvasive and invasive tests.

Design.  Population‐based study.

Subjects.  A total of 100 patients with BFB, of whom 41 had a history of unexplained syncope, were prospectively studied. The mean age was 68 ± 12. All patients were investigated with Holter‐monitoring, an exercise test, an echocardiography, and an invasive electrophysiological study. The severity of congestive heart failure (CHF) was assessed by New York Heart Association (NYHA) classification. Patients in NYHA class IV were excluded.

Interventions.  Patients with syncope were recommended prophylactic pacemaker treatment, which was accepted by 31 patients (76%).

Main outcome measures.  All‐cause mortality and sudden cardiac death (SCD).

Results.  During a median follow‐up of 84 months, 33 patients died, of whom 14 in SCD. In a univariate analysis, high age, a previous myocardial infarction, and CHF were associated with a significantly increased risk of all‐cause mortality and SCD. In a Cox multiple regression analysis, CHF was the only independent predictor of all‐cause mortality and SCD (P < 0.01).

Conclusion.  Patients with BFB have a poor long‐term prognosis. The predictive value of noninvasive and invasive investigations is limited. The only independent predictor of all‐cause mortality and SCD in this population was the presence of CHF.
Surface characteristics of aesthetic restorative materials – an SEM study
Authors: BAGHERI R. , BURROW M. F. , TYAS M. J.
Published: April 2006

summary  To determine the degree of surface roughness of glass–ionomer cements (GICs) and polyacid‐modified resin composite (PAMRC) after polishing and immersion in various foodstuffs. Three tooth‐coloured restorative materials were used: a PAMRC (F2000), a conventional glass–ionomer cement (CGIC) (Fuji IX) and a resin‐modified glass–ionomer cements (RM‐GIC) (Fuji II LC). Disk‐shaped specimens were prepared and tested with either a plastics matrix finish or after polishing with wet silicon carbide papers up to 2000‐grit. All specimens were immersed in 37 °C‐distilled water for 1 week, followed by three different foodstuffs (red wine, coffee or tea) for a further 2 weeks. Replicas of specimens were prepared by taking polyvinyl siloxane impressions, casting in epoxy resin, gold sputter‐coating and examining using a Field‐Emission Scanning Electron Microscope. The polished and matrix finish specimens of F2000 showed many microcracks at low magnification, and eroded surfaces with missing and protruding particles at high magnification in the polished specimens. The surface‐polished specimens of Fuji II LC were considerably rougher than the matrix‐finish specimens, with large voids and protruding filler particles. The effects of foodstuffs on Fuji II LC and F2000 were not noticeable. The CGIC became noticeably rougher after exposure to coffee and tea. All specimens had the smoothest surface when they were cured against a plastics matrix strip, and all materials had a rougher surface after polishing. None of the foodstuffs produced a perceptible increase in roughness on RM‐GIC and PAMRC surfaces, whereas coffee and tea markedly increased the surface roughness of Fuji IX.
The effect of income growth on the mix of purchases between disposable goods and reusable goods
Authors: McCollough John
Published: April 2006

With each passing year consumers find more and more disposable goods for sale in the market place. Even goods that were considered to be reusable goods just a few years back are now disposable goods. As a result the American economy has been labelled a ‘throwaway society’. This paper examines a main underlying cause for this trend by linking growth in consumer income with the purchases of disposable goods. More specifically, the model proposes that as incomes rise, consumers will purchase more of both reusable goods and disposable goods. However, as incomes rise, consumers will naturally substitute purchases away from reusable goods and into disposable goods. The shift towards disposable goods occurs because it becomes too costly for consumers to spend their time repairing and maintaining products. Their time is better spent in more productive endeavours. It is simply cheaper (in terms of opportunity cost of time) to dispose of old products and replace them with new products.
Development of polymorphic simple sequence repeat markers for Pisolithus microcarpus
Authors: HITCHCOCK CATHERINE J. , CHAMBERS SUSAN M. , CAIRNEY JOHN W. G.
Published: April 2006

Six polymorphic simple sequence repeat (SSR) markers were developed for the ectomycorrhizal fungus Pisolithus microcarpus. A polymerase chain reaction (PCR)‐based technique was used in which random amplified polymorphic DNA (RAPD) fingerprints were probed with labelled SSR oligonucleotides by southern hybridization. The number of alleles per locus ranged from two to nine with expected heterozygosity values from 0.33 to 0.76. These loci will be potentially useful for genetic structure and gene flow studies of P. microcarpus populations. Cross‐species amplification with Pisolithus albus isolates at all loci was also observed.
Mechanomyography and electromyography during and after fatiguing shoulder eccentric contractions in males and females
Authors: Kawczyński A. , Nie H. , Jaskólska A. , Jaskólski A. , Arendt‐Nielsen L. , Madeleine P.
Published: April 2006

The aim of this study was to investigate changes in mechanomyographic (MMG) and the surface electromyographic (EMG) signals during and after fatiguing shoulder eccentric contractions in a group consisting of 12 males and 12 females. Exerted force, MMG, EMG, pain and rate of perceived exertion were assessed before, during and after repeated high‐intensity eccentric exercises. Bouts of eccentric contractions caused a decrease in the exerted force for males (P<0.05) and an increase in the rate of perceived exertion and pain for both genders (P<0.05). During eccentric exercise, the root mean square (RMS) values of the MMG signal increased (P<0.05). The mean power frequency (MPF) values of the EMG signal decreased at the end of each eccentric bout for both genders (P<0.05); the decrease was higher for females compared with males (P<0.05). Immediately after eccentric exercise in static abduction of the upper limbs, the MMG RMS and MPF values increased (P<0.05). The present study showed that (1) neuromuscular changes associated with pain and changes in muscle stiffness and (2) changes in motor units strategy during fatigue development in shoulder muscle are reflected in the MMG and EMG signals.
An Extension of the Imploding Can Demonstration
Authors: Gratton L. M. , Oss S.
Published: April 2006

In this paper we address some fascinating aspects of the well-known, simple demonstration of a collapsing can. An Internet search on “collapsing can” or “imploding can” gives more than 700 hits.1 Because physics and physics teaching journals have not given a corresponding amount of attention to this experiment,2 we decided to make our own contribution to the literature. We show that a careful study of the crushing can experiment introduces a very wide range of conceptual and practical topics in classical thermodynamics. We especially suggest a simple experimental extension that allows much more information on the physical behavior of the imploding can to be easily obtained.
Reverse-Engineering the Solution of a “Simple” Physics Problem: Why Learning Physics Is Harder Than It Looks
Authors: Redish Edward F. , Scherr Rachel E. , Tuminaro Jonathan
Published: April 2006

In this paper, we show an example of students working on a physics problem—an example that demonstrated to us that we had failed to understand the work they needed to do in order to solve a “simple” problem in electrostatics. Our critical misunderstanding was failing to realize the level of complexity that was built into our own knowledge about physics.
Antispermatogenic Activity of the Benzothiazoline Ligand and Corresponding Organoantimony(V) Derivative in Male Albino Rats
Authors: Sharma Pankaj K. , Rehwani H. , Rai A. K. , Gupta R. S. , Singh Y. P.
Published: April 2006

Triphenylantimony(V) derivative, Ph3Sb(OPri)[SC6H4N : C(CH3)CH2C(O)CH3], 1b, and the corresponding benzothiazoline ligand [1, 2],
, 1a, have been tested for their effects on the
reproductive system of male albino rats. The oral administration
of both 1a and 1b at the dose level of 10 mg/rat/day produced
significant reduction in the weights of testes, epididymides,
seminal vesicles, and ventral prostate. Significant decrease in
sperm motility as well as in sperm density resulted in 100%
sterility. Significant (P < .01) alterations were also found in biochemical parameters
of reproductive organs in treated male rats as compared to the
control group. Production of preleptotene, pachytene, and
secondary spermatocytes was decreased by 42%, 43%,
39%, and by 44%, 49%, 55% in the ligand,
1a, and organoantimony(V) derivative, 1b, treated rats, respectively. These results indicate
that both compounds 1a and 1b are antispermatogenic in nature and on oral
administration in male rats, and finally caused sterility. A
comparison indicates that the organoantimony(V) derivative
1b is more effective pertaining to its antispermatogenic
activity than the corresponding ligand 1a.
Constitutive Expression of Functionally Active Protease‐Activated Receptors 1 and 2 in Human Conjunctival Epithelial Cells
Authors: Nickel Timothy J. , Kabir Mohammad H. , Talreja Jaya , Stechschulte Daniel J. , Dileepan Kottarappat N.
Published: April 2006

Protease‐activated receptors (PARs) are G‐protein‐coupled receptors which initiate inflammatory responses when activated by specific serine proteases. This study was conducted to examine whether human conjunctival epithelial cells (HCECs) express functionally active PAR1 and PAR2 using Chang conjunctival
epithelial cells as in vitro model. We performed RT‐PCR and immunofluorescence analyses to determine the expression of PAR1 and PAR2, and monitored the production of IL‐6 after activating HCECs with PAR1 activating agents (thrombin or TFLLRN) or PAR2 activating agents (tryptase, trypsin, or SLIGKV). The results show that HCECs constitutively express PAR1 and PAR2 mRNA and proteins, and produce significant amounts of IL‐6 when incubated with specific PAR‐activating enzymes or agonist peptides. Thrombin‐ and tryptase‐induced HCEC activation was blocked by PAR1 and PAR2 neutralizing antibodies, respectively, and by specific enzyme inhibitors. The constitutive expression of PAR1 and PAR2, and their activation by thrombin and tryptase, respectively, may have important implications in ocular inflammation.
A dual-genome microarray for the pea aphid, Acyrthosiphon pisum, and its obligate bacterial symbiont, Buchnera aphidicola
Authors: Wilson Alex CC , Dunbar Helen E , Davis Gregory K , Hunter Wayne B , Stern David L , Moran Nancy A
Published: April 2006

Background

The best studied insect-symbiont system is that of aphids and their primary bacterial endosymbiont Buchnera aphidicola. Buchnera inhabits specialized host cells called bacteriocytes, provides nutrients to the aphid and has co-speciated with its aphid hosts for the past 150 million years. We have used a single microarray to examine gene expression in the pea aphid, Acyrthosiphon pisum, and its resident Buchnera. Very little is known of gene expression in aphids, few studies have examined gene expression in Buchnera, and no study has examined simultaneously the expression profiles of a host and its symbiont. Expression profiling of aphids, in studies such as this, will be critical for assigning newly discovered A. pisum genes to functional roles. In particular, because aphids possess many genes that are absent from Drosophila and other holometabolous insect taxa, aphid genome annotation efforts cannot rely entirely on homology to the best-studied insect systems. Development of this dual-genome array represents a first attempt to characterize gene expression in this emerging model system.

Results

We chose to examine heat shock response because it has been well characterized both in Buchnera and in other insect species. Our results from the Buchnera of A. pisum show responses for the same gene set as an earlier study of heat shock response in Buchnera for the host aphid Schizaphis graminum. Additionally, analyses of aphid transcripts showed the expected response for homologs of known heat shock genes as well as responses for several genes with unknown functional roles.

Conclusion

We examined gene expression under heat shock of an insect and its bacterial symbiont in a single assay using a dual-genome microarray. Further, our results indicate that microarrays are a useful tool for inferring functional roles of genes in A. pisum and other insects and suggest that the pea aphid genome may contain many gene paralogs that are differentially regulated.
Deletions in the Y-derived amelogenin gene fragment in the Indian population
Authors: Kashyap VK , Sahoo Sanghamitra , Sitalaximi T , Trivedi R
Published: April 2006

Background

Rare failures in amelogenin-based gender typing of individuals have been observed globally. In this study, we report the deletion of a large fragment of the amelogenin gene in 10 individuals out of 4,257 male samples analyzed from 104 different endogamous populations of India.

Methods

Samples were analyzed using commercial genetic profiling kits. Those that exhibited failures in amelogenin-based gender identification were further analyzed with published as well as newly designed primers to ascertain the nature and extent of mutation.

Results

The failure rate among Indian males was 0.23 %. Though the exact size and nature of the deletion (single point mutations at a number of positions or a single large deletion) could not be determined in the present study, it is inferred that the deletion spans a region downstream of the reverse primer-binding site of commercially available amelogenin primer sets. Deletions were conspicuously absent among the Mongoloid tribes of Northeast India, while both caste and tribal groups harbored these mutations, which was predominantly among the Y-chromosomes belonging to J2 lineage.

Conclusion

Our study indicates that the different amelogenin primer sets currently included in genetic profiling multiplex kits may result in erroneous interpretations due to mutations undetectable during routine testing. Further there are indications that these mutations could possibly be lineage-specific, inherited deletions.
Handwriting performance in the absence of visual control in writer's cramp patients: Initial observations
Authors: Chakarov Vihren , Hummel Sibylla , Losch Florian , Schulte-Mönting Jürgen , Kristeva Rumyana
Published: April 2006

Background

The present study was aimed at investigating the writing parameters of writer's cramp patients and control subjects during handwriting of a test sentence in the absence of visual control.

Methods

Eight right-handed patients with writer's cramp and eight healthy volunteers as age-matched control subjects participated in the study. The experimental task consisted in writing a test sentence repeatedly for fifty times on a pressure-sensitive digital board. The subject did not have visual control on his handwriting. The writing performance was stored on a PC and analyzed off-line.

Results

During handwriting all patients developed a typical dystonic limb posture and reported an increase in muscular tension along the experimental session. The patients were significantly slower than the controls, with lower mean vertical pressure of the pen tip on the paper and they could not reach the endmost letter of the sentence in the given time window. No other handwriting parameter differences were found between the two groups.

Conclusion

Our findings indicate that during writing in the absence of visual feedback writer's cramp patients are slower and could not reach the endmost letter of the test sentence, but their level of automatization is not impaired and writer's cramp handwriting parameters are similar to those of the controls except for even lower vertical pressure of the pen tip on the paper, which is probably due to a changed strategy in such experimental conditions.
Absorbing and transferring risk: assessing the impact of a statewide high-risk-pregnancy telemedical program on VLBW maternal transports
Authors: Britt David W , Bronstein Janet , Norton Jonathan D
Published: April 2006

Background

Prior research has shown that resources have an impact on birth outcomes. In this paper we ask how combinations of telemedical and hospital-level resources impact transports of mothers expecting very low birth weight (VLBW) babies in Arkansas.

Methods

Using de-identified birth certificate data from the Arkansas Department of Health, data were gathered on transports of women carrying VLBW babies for two six-month periods: a period just before the start of ANGELS (12/02-05/03), a telemedical outreach program for high-risk pregnancies, and a period after the program had been running for six months (12/03-05/04). For each maternal transport, the following information was recorded: maternal race-ethnicity, maternal age, and the birth weight of the infant. Logistic regression was used to assess the relationship between the predictors (telemedicine, hospital level, maternal characteristics) and the probability of a transport.

Results

Having a telemedical site available increases the probability of a mother carrying a VLBW baby being transported to a level III facility either before or during birth. Having at least a level II nursery also increases the chance of a maternal transport. Where both level II nurseries and telemedical access are available, the odds of VLBW maternal transports are only modestly increased in comparison to the case where neither is present. At the individual level, Hispanic mothers were less likely to be transported than other mothers, and teenaged mothers were more likely to be transported than those 18 and over. A mother's being Black or being over 35 did not have an impact on the odds of being transported to a level III facility.

Conclusion

Combinations of resources have an impact on physician decisions regarding VLBW transports and are interpretable in terms of the capacity to diagnose and absorb risk. We suggest a collegial review of transport patterns and birth outcomes from areas with different levels of resources as a vehicle for moving the entire system of care forward over time. With such an evidence-based review in place, the collegial relations among level III specialists and obstetricians from around the state can, over time, develop workable protocols for when and how level III facilities should be involved.
Measuring troublesomeness of chronic pain by location
Authors: Parsons Suzanne , Carnes Dawn , Pincus Tamar , Foster Nadine , Breen Alan , Vogel Steven , Underwood Martin
Published: April 2006

Background

Current measures of pain assess the relative contribution of pain in different body regions to the overall impact of pain. We developed a series of questions to measure the relative 'troublesomeness' of pain in different body regions (the "troublesomeness grid"). The study aimed to determine whether the "troublesomeness grid" is an appropriate measure to assess the severity of pain in different body regions, allowing the comparative severity of pain in different body regions to be assessed.

Methods

We used data from a pilot for a population survey of pain (N = 205) and from the population survey itself (N = 2504) to assess the 'troublesomeness grid's performance. Specifically, its face and content validity using overall and item non-completion rates; its criterion related validity by exploring the relationship between troublesomeness and standard measures of pain, disability, distress and health utility for the five body regions most commonly affected by chronic pain; and its reliability and reproducibility in a test/re-test study.

Results

The troublesomeness grid appeared to have good face validity as it had good completion rates. It also appeared to have good content validity as the percentage agreement between the grid and the pain manikin was high (over 90%). In terms of criterion related validity, troublesomeness was most strongly correlated with pain intensity and health related quality of life, but less with disability and distress. The test-retest reliability was between 80% and 90% for the majority of body regions examined.

Conclusion

The troublesomeness grid is well completed and appears to be an appropriate tool to assess the comparative severity of pain in different body regions.
Cardiac dysfunction in the diabetic rat: quantitative evaluation using high resolution magnetic resonance imaging
Authors: Loganathan Rajprasad , Bilgen Mehmet , Al-Hafez Baraa , Alenezy Mohammed D , Smirnova Irina V
Published: April 2006

Background

Diabetes is a major risk factor for cardiovascular disease. In particular, type 1 diabetes compromises the cardiac function of individuals at a relatively early age due to the protracted course of abnormal glucose homeostasis. The functional abnormalities of diabetic myocardium have been attributed to the pathological changes of diabetic cardiomyopathy.

Methods

In this study, we used high field magnetic resonance imaging (MRI) to evaluate the left ventricular functional characteristics of streptozotocin treated diabetic Sprague-Dawley rats (8 weeks disease duration) in comparison with age/sex matched controls.

Results

Our analyses of EKG gated cardiac MRI scans of the left ventricle showed a 28% decrease in the end-diastolic volume and 10% increase in the end-systolic volume of diabetic hearts compared to controls. Mean stroke volume and ejection fraction in diabetic rats were decreased (48% and 28%, respectively) compared to controls. Further, dV/dt changes were suggestive of phase sensitive differences in left ventricular kinetics across the cardiac cycle between diabetic and control rats.

Conclusion

Thus, the MRI analyses of diabetic left ventricle suggest impairment of diastolic and systolic hemodynamics in this rat model of diabetic cardiomyopathy. Our studies also show that in vivo MRI could be used in the evaluation of cardiac dysfunction in this rat model of type 1 diabetes.