bluuebunny/crossref_metadata_2025 huggingface dataset:
Creeping motion of a sphere along the axis of a closed axisymmetric container
Authors: LECOQ N. , MASMOUDI K. , ANTHORE R. , FEUILLEBOIS F.
Published: August 2007

The creeping flow around a sphere settling along the axis of a closed axisymmetric container is obtained both theoretically and experimentally. The numerical technique for solving the Stokes equations uses the classical Sampson expansion; the boundary conditions on the sphere are satisfied exactly and those on the container walls are applied in the sense of least squares. This is an extension to the axisymmetric case of the technique for solving various two-dimensional flow problems. Two types of axisymmetric container are considered here as examples: circular cylinders closed by planes at both ends, and cones closed by a base plane. Calculated streamlines patterns show various sets of eddies, depending upon the geometry and the sphere position. Results are in agreement with earlier Stokes flow calculations of eddies in corners and in closed containers. Experiments use laser interferometry to measure the vertical displacement of a steel bead a few millimetres in diameter settling in a container filled with a very viscous silicone oil. The Reynolds number based on the sphere radius is typically of the order of 10−5. The accuracy on the vertical displacement is 50nm. Experiments show that the motion towards the apex of a cone is much slower than that towards a plane; the bead takes hours to reach the micrometre size roughness asperities on a conical wall, as compared with minutes to reach those on a plane wall. The numerical results for the drag force are in excellent agreement with experiments both for the cylindrical and the conical containers. With standard computer accuracy, the present numerical technique applies when the gap between the sphere and the nearby wall is larger than about one radius. For a sphere in the vicinity of any plane horizontal wall, these results also match with a previous analytical solution. That solution is in excellent agreement with our experimental results at small distances from the wall (typically less than a diameter, depending on the sphere size).
The waterlogging of floating objects
Authors: VELLA DOMINIC , HUPPERT HERBERT E.
Published: August 2007

We consider the dynamical processes by which a dense, porous object floating in a body of liquid becomes waterlogged and sinks. We first generalize the classic model of capillary rise in a porous medium to present an analytically tractable model of the process, which is valid for objects that are very shallow compared to their horizontal extent. We find an analytical expression for the time taken for the object to sink under this approximation. We use a series of boundary integral simulations to show that decreasing the horizontal extent of the object decreases the time taken to sink. We find that the results of these numerical simulations are in good quantitative agreement with a series of laboratory experiments. Finally, we discuss the implications of our work for pumice fragments, often found floating in open water after a volcanic eruption, occasionally even supporting plant, animal and human remains.
Glacially induced organization of channel‐reach morphology in mountain streams
Authors: Brardinoni Francesco , Hassan Marwan A.
Published: August 2007

We examine the spatial distribution of channel‐reach morphologies in formerly glaciated mountain drainage basins of coastal British Columbia, Canada. Using field‐ and geographic information systems‐derived data, we show that the local channel slope and the degree of colluvial‐alluvial coupling imposed by the glacial valley morphology dictate the spatial organization of channel types. In particular, the complex, glacially induced channel long profile produces characteristic sequences of channel reaches that depart from the downstream succession (colluvial/boulder‐cascade/step‐pool/rapids/riffle‐pool) distinctive of simple unglaciated mountain streams. Typically, the presence of one hanging valley in the river long profile produces and separates two full successions of channel types: a headmost one characterized by an ephemeral/seasonal hydrologic regime and a downstream one, where water runoff is perennial. We document that channel types are well separated in plots of slope versus shear stress, area versus shear stress, and slope versus relative roughness. In agreement with these outcomes, multivariate discriminant analyses coupled with principal component analysis of 98 study reaches yield a highly successful channel‐type classification when slope, shear stress, and relative roughness are considered. Success rates, depending on whether or not boulder‐cascade reaches are pooled together with step‐pools, are 88% and 75%, respectively. Previous work in unglaciated settings has suggested that mountain channels have distinct bed morphology states that vary primarily with slope; our study reveals that even in formerly glaciated valleys, where slope is largely inherited from glacial times, these distinct bed states exist and vary (mostly) with slope, adding considerable strength to this empirical knowledge.
El Niño as a mediator of the solar influence on climate
Authors: Emile‐Geay Julien , Cane Mark , Seager Richard , Kaplan Alexey , Almasi Peter
Published: August 2007

Using a climate model of intermediate complexity, we simulate the response of the El Niño–Southern Oscillation (ENSO) system to solar and orbital forcing over the Holocene. Solar forcing is reconstructed from radiocarbon production rate data, using various scaling factors to account for the conflicting estimates of solar irradiance variability. As estimates of the difference since the Maunder Minimum range from 0.05% to 0.5% of the solar “constant,” we consider these two extreme scenarios, along with the intermediate case of 0.2%. We show that for large or moderate forcings, the low‐pass‐filtered east‐west sea surface temperature gradient along the equator responds almost linearly to irradiance forcing, with a short phase lag (about a decade). Wavelet analysis shows a statistically significant enhancement of the century‐to‐millennial‐scale ENSO variability for even a moderate irradiance forcing. In contrast, the 0.05% case displays no such enhancement. Orbitally driven insolation forcing is found to produce a long‐term increase of ENSO variability from the early Holocene onward, in accordance with previous findings. When both forcings are combined, the superposition is approximately linear in the strong scaling case. Overall, the sea surface temperature response is of the magnitude required, and is persistent enough, to induce important climatic perturbations worldwide. The results suggest that ENSO may plausibly have acted as a mediator between the Sun and the Earth's climate. A comparison to key Holocene climate records, from the Northern Hemisphere subtropics and midlatitudes, shows support for this hypothesis.
Localized three‐dimensional ionospheric tomography with GPS ground receiver measurements
Authors: Lee Jeffrey K. , Kamalabadi Farzad , Makela Jonathan J.
Published: August 2007

This paper describes a technique for 3‐D tomographic imaging of the ionosphere with high spatial resolution (75 to 95 km in latitude/longitude and 30 km in altitude). The total electron content (TEC) values are derived from dual‐frequency measurements obtained from GPS satellites by ground‐based receivers. When available, ionosonde data are used to construct a priori vertical profiles modeled using Chapman functions. Two regularization algorithms are investigated for tomographic image reconstruction: Tikhonov and Total Variation (TV), corresponding to quadratic and l1 norm minimizations of the penalty constraint, respectively. The TV method is used because it generally preserves discontinuities in the image effectively and is more resistant to noise. By contrast, Tikhonov, or quadratic, regularization tends to oversmooth image structures and discontinuities. However, a closed‐form solution of the TV method does not exist and so performance depends heavily on numerical optimization techniques, which are nontrivial to implement because the inverse problem is both ill‐posed and ill‐conditioned. We also apply regularization parameter‐selection methods to demonstrate their applicability in our study. The algorithms are demonstrated using real GPS TEC measurements from an observation geometry centered in southern California. We demonstrate the performance of these techniques under quiet, midlatitude conditions. The resulting reconstructions reasonably determine the shape of the ionospheric profile. Artifacts can potentially appear near voxels with no raypath information, which is directly related to the sparseness and nonuniform distribution of the GPS raypaths. We discuss some methods to constrain the solution to realistic bounds.
Signal strength variations at 2 GHz for three sea paths in the British Channel Islands: Observations and statistical analysis
Authors: Siddle D. R. , Warrington E. M. , Gunashekar S. D.
Published: August 2007

Measurements of signal strength are reported for a study of UHF propagation on three transhorizon sea paths in the British Channel Islands. Enhancements of up to 30 dB from the mean occur for periods of hours or days, especially in the summer, and constitute about 5% of the overall data. The probability distribution of received power is tabulated for the three paths and various antenna heights, and is compared with predictions of signal strength using ITU‐R Recommendation P.1546‐2. The difference between median and upper decile in the data is much less than predicted, whereas the difference between upper decile and the upper percentile is much greater than predicted.
An Antarctic ice‐related “superbloom” observed with the MERIS satellite imager
Authors: Gower Jim , King Stephanie
Published: August 2007

MERIS (Medium Resolution Imaging Spectrometer) satellite imagery for early March 2006 shows streaks and patches of what appears to be an intense plankton bloom among broken ice off Ronne Entrance, Antarctica, near 73 S, 83 W. The streaks are 2 to 10 km wide and up to 100 km long, extending across open water between land and the ice edge. We interpret these streaks as an example of a previously reported type of “superbloom,” in which very high surface concentrations of chlorophyll occur in water containing ice platelets. Spectral bands of the MERIS satellite imager in the visible and near‐infrared allow computation of an index suitable for detection of surface blooms containing high concentrations of chlorophyll, especially blooms associated with high‐scattering from suspended sediment or ice. The images presented here suggest a new way in which MERIS images can contribute to the study of primary productivity in polar regions.
Relationships between lightning and properties of convective cloud clusters
Authors: Futyan Joanna M. , Del Genio Anthony D.
Published: August 2007

Satellite observations of convective system properties and lightning flash rate are used to investigate the ability of potential lightning parameterizations to capture both the dominant land‐ocean contrast in lightning occurrence and regional differences between Africa, the Amazon and the islands of the maritime continent. As found in previous studies, the radar storm height is tightly correlated with the lightning flash rate. A roughly second order power‐law fit to the mean radar echo top height above the 0°C isotherm is shown to capture both regional and land‐ocean contrasts in lightning occurrence and flash rate using a single set of parameters. Recent developments should soon make it possible to implement a parameterization of this kind in global models. Parameterizations based on cloud top height, convective rain rate and convective rain fraction all require the use of separate fits over land and ocean and fail to capture observed differences between continental regions.
Amplification of Holocene multicentennial climate forcing by mode transitions in North Atlantic overturning circulation
Authors: Jongma J. I. , Prange M. , Renssen H. , Schulz M.
Published: August 2007

Using a three‐dimensional global climate model, we show that mode‐transitions in North Atlantic deep‐water production can provide an amplifying mechanism of relatively weak climate perturbations during the Holocene. Under pre‐industrial boundary conditions, a freshwater forcing in the Labrador Sea pushes the North Atlantic overturning circulation into a deterministically bistable regime, characterized by stochastic “on” and “off” switches in Labrador Sea convection. On a multicentennial time‐scale these stochastic mode‐transitions can be phase‐locked by a small (subthreshold) periodic freshwater forcing. The local small periodic forcing is effectively amplified with the assistance of noise, to have a large‐scale impact on North Atlantic overturning circulation and climate. These results suggest a stochastic resonance mechanism that can operate under Holocene boundary conditions and indicate that changes in the three‐dimensional configuration of North Atlantic deep‐water formation can be an important component of multicentennial climate variability during interglacials.
Biogenic 2‐methyl‐3‐buten‐2‐ol increases regional ozone and HOx sources
Authors: Steiner Allison L. , Tonse Shaheen , Cohen Ronald C. , Goldstein Allen H. , Harley Robert A.
Published: August 2007

We present the first regional‐scale chemistry simulation investigating the effects of biogenic 2‐methyl‐3‐buten‐2‐ol (MBO) emissions on air quality. In a central California model domain, MBO emissions have a distinctly different regional pattern than isoprene but have similar daily maxima of about 5 mg m−2 hr−1. MBO oxidation causes an increase in ozone, formaldehyde, acetone and consequently hydrogen radical production (PHOx). The addition of MBO increases the daily maximum ozone as much as 3 ppb near source regions (2–5% in rural areas) and as much as 1 ppb in the Central Valley. Formaldehyde concentrations increase by as much as 1 ppb (40%) over the Sierra Nevada Mountains, increasing the production of HOx by 10–20% and accelerating local chemistry. This indicates that inclusion of MBO and other biogenic oxygenated emissions in regional simulations in the western and southeastern United States is essential for accurate representation of ozone and HOx.
THE INCREASE IN TESTICULAR VASCULAR PERMEABILTY INDUCED BY HUMAN CHORIONIC GONADOTROPHIN INVOLVES 5‐HYDROXYTRYPTAMINE AND POSSIBLY OESTROGENS, BUT NOT TESTOSTERONE, PROSTAGLANDINS, HISTAMINE OR BRADYKININ
Authors: Sowerbutts SF , Jarvis LG , Setchell BP
Published: August 2007

Possible intermediates in the response of the rat testicular vasculature to human chorionic gonadotrophin (hCG) have been investigated. Ketanserin, an antagonist of 5‐hydroxytryptamine, significantly reduced the increase in 1‐h albumin space seen 20 h after hCG, as did one aromatase inhibitor (1,4,6‐androstatriene‐3, 17‐dione), but the effect of another (testolactone) did not reach significance. Aminoglutethimide, which inhibits overall steroid synthesis as well as aromatase, reduced the albumin space in both control and hCG‐injected rats but the hCG response, as judged by the ratio between treated and control rats, was unaffected. Inhibitors of overall steroid synthesis (WIN 32,729), prostaglandin synthesis (meclofenamic acid or indomethacin) and angiotensin converting enzyme (captopril) and blockers of H1 and H2 histamine receptors (mepyramine, cimetidine or ranitidine) were without effect. The time course of the vascular response to hCG is quite different from the response in testosterone secretion by the testis. Considerable numbers of mast cells were found in the vicinity of the testicular artery in the testicular capsule, and these may be a source of 5‐hydroxytryptamine.
THE PRODUCTION OF HYDROXYL RADICAL BY HUMAN NEUTROPHILS STIMULATED BY ARACHIDONIC ACID – MEASUREMENTS BY ESR SPECTROSCOPY
Authors: Cheung Kee , Lark Jennifer , Robinson Michael F , Pomery Peter J , Hunter S
Published: August 2007

Human neutrophils incubated with sodium arachidonate generated hydroxyl radicals. The radical formed an adduct with the spin trap 5′, 5‐dimethyl‐l‐pyrroline‐N‐oxide (DMPO) and was subsequently detected by electron spin resonance (ESR) spectroscopy. The ESR signal was inhibited by mannitol and superoxide dismutase but not by catalase. Removal of glucose from the reaction mixture or the presence of glucose metabolic inhibitors including 2‐deoxy‐D‐glucose and 3‐O‐methyl‐D‐glucose did not affect the production of hydroxyl radical by the neutrophils. The ESR signal was, however, inhibited by the lipoxygenase inhibitors nordihydroguaiaretic acid and N‐ethylmaleimide.

The involvement of lipoxygenase in the production of hydroxyl radical was demonstrated by the trapping of the radical with DMPO in a reaction mixture of soybean lipoxygenase and arachidonic acid (AA). These findings support our previous postulation that the metabolism of AA via the lipoxygenase pathway is a source of hydroxyl radical in stimulated neutrophils.
A COMPARISON OF PORTAL VERSUS SYSTEMIC VENOUS DRAINAGE IN MURINE FOETAL PANCREATIC ISLET TRANSPLANTATION
Authors: Cuthbertson RA , Mandel TE
Published: August 2007

We have compared the efficiency of foetal islet graft growth and function in renal subcapsular (systemic drainage) and splenic (portal drainage) sites. Age‐matched female BALB/c streptozotocin (STZ)‐diabetic mice were grafted either under the left renal capsule or on to the hilar surface of the spleen with one half of a syngeneic 17‐day gestation foetal pancreas which had been in organ culture for 2 weeks. Gain in body weight, return to normoglycaemia and to normal glycosylated haemoglobin levels were not significantly different between the two groups. However, when an intraperitoneal arginine challenge was performed the portally grafted mice showed more normal responses than the systemically grafted mice. Although still not normal after the arginine challenge, mean blood glucose values were lower and serum insulin values higher in the spleen grafted animals than in the renal subcapsular graft group. The total amount of insulin was assayed by extraction of both the graft and the pancreas of each animal. The amount of insulin in the grafts from the spleen was not significantly different from those in the renal subcapsular site. We conclude that the efficiency of a graft draining into the portal circulation is greater than an equivalent sized graft draining systemically when a maximal challenge is applied.
THE ROLE OF GUT‐ASSOCIATED LYMPHOID TISSUES IN THE GENERATION OF IMMUNOGLOBULIN‐BEARING LYMPHOCYTES IN SHEEP
Authors: Gerber HA , Morris Bede , Trevella Wendy
Published: August 2007

Experiments were designed to examine the relative contributions of Peyer's patches and mesenteric lymph nodes to the population of circulating immunoglobulin‐bearing lymphocytes in sheep. The ileum, with more than 90% of the total Peyer's patches, the mesenteric lymph nodes, or both, were removed from lambs at different stages of development and the composition of the cell populations in lymph from different sources and in the blood was examined. Lambs which had had the ileum removed before or within a few days of birth were deficient in small lymphocytes bearing membrane immunoglobulin. This deficit remained for at least the first year of the animals' lives. Neither the removal of mesenteric lymph nodes nor removal of the ileum had any statistically significant effect on the total output of cells or on the population of IgA‐producing cells in lymph draining from the gut.
ASPECTS OF PATHOGENESIS IN A MOUSE MODEL OF INFECTION BY CORYNEBACTERIUM PSEUDOTUBERCULOSIS
Authors: Batey RG
Published: August 2007

A new medium, nutrient tween 80 broth (NTB) was utilised to achieve improved cultivation of Corynebacterium pseudotuberculosis. Twenty four hour NTB cultures were used for cutaneous and intraperitoneal infection of mice. The intraperitoneal administration of heterologous protein, liquid paraffin or thioglycollate prior to intraperitoneal challenge caused enhanced multiplication of the organism although this could be prevented by modifying host response. Pretreatment of skin with thioglycollate enabled cutaneous infection to be consistently achieved. The progress of lesions in skin and viscera is described. Immunisation of the mice was effected by both intraperitoneal and cutaneous routes of inoculation, the latter being particularly useful because it did no t lead to residual lesions of viscera. Immunity was expressed by a failure of organisms to localise at secondary sites although infection of primary sites in skin or peritoneal cavity occurred, apparently at a reduced level. The relevance of these findings to the natural disease of sheep is discussed.
HUMAN ARBOVIRUS INFECTIONS ALONG THE SOUTH COAST OF NEW SOUTH WALES
Authors: Vale TG , Carter IW , McPhie KA , James GS , Cloonan MJ
Published: August 2007

The prevalence of antibodies in human sera from the south coast of New South Wales to four arboviruses, isolated from mosquitoes collected along the south coast, was determined in an attempt to estimate the importance of these viruses in human infection. Only two viruses, Barmah Forest and Gan Gan, were considered to be of any significance.
EPIDERMAL CELL POPULATIONS AND ANTIGEN EXPRESSION IN CULTURES OF HUMAN NEONATAL EPIDERMIS
Authors: Thompson CH , Rose BR , Cossart YE
Published: August 2007

The persistence of Langerhans cells, melanocytes and ABH red cell antigens in human epidermal cell cultures derived from neonatal foreskin explants has been investigated. Langerhans cells were recognised via the detection of ATPase activity and by immunohistochemical staining for T6 and HLA‐DR antigens. Melanocytes were detected by the dihydroxyphenylalanine (DOPA) technique; whilst the presence of red cell antigens was confirmed by immunohistochemical tests using monoclonal anti‐A, anti‐B, and anti‐H antibodies.

Langerhans cells were not detected in the cultured epidermis, and few melanocytes were found more than 0.2 mm from the periphery of the explants. However, both Langerhans cells and melanocytes were found to persist for up to 4 weeks in the explants themselves. Red cell antigens, consistent with the blood group of the donor infant, were consistently detected on the surface of the differentiating keratinocytes throughout their in vitro lifespan. The significance of these findings is discussed.
CONJUGATIVE, STAPHYLOCOCCAL PLASMIDS CARRYING HITCH‐HIKING TRANSPOSONS SIMILAR TO Tn554: INTRA‐AND INTERSPECIES DISSEMINATION OF ERYTHROMYCIN RESISTANCE
Authors: Townsend DE , Bolton S , Ashdown N , Annear DI , Grubb WB
Published: August 2007

Two staphylococcal plasmids, pWG4 and pWG25, encode production of a diffusible pigment and resistance to erythromycin and spectinomycin. The former was found occurring naturally in a clinical isolate of Staphylococcus aureus and the latter in S. epidermidis. Both plasmids are conjugative, capable of high‐frequency, interspecies transfer, only isolated in the open‐circular form and identical in molecular weight and pattern of restriction‐endonuclease fragments. The only difference between the plasmids is in the expression of resistance, pWG4 encoding inducible and pWG25 constitutive erythromycin resistance. The resistance determinants of both plasmids behave as hitch‐hiking transposons in cultural conditions that favour phage‐mediated or phage‐independent conjugation, always inserting a copy of themselves into the recipient's chromosome, except in S. epidermidis in which the chromosomal insertion site may be absent. The resistance determinants have been cloned and located on a 4 7 kbp Eco Rl/Hind III restriction fragment which has a restriction map similar to that of the right arm of Tn554 (Murphy and Lofdahl, 1984). The hitch‐hiking transposon of plasmid pWG25 has been designated Tn3853.
INCREASED PRODUCTION OF ARACHIDONATE METABOLITES BY PERITONEAL CELLS OF MICE INFECTED WITH PLASMODIUM VINCKEI VINCKEI
Authors: Clark IA , Hunt NH
Published: August 2007

Peritoneal cells from mice infected with Plasmodium vinckei vinckei generate about four times more prostaglandin F and 6‐keto prostaglandin F1α, five times the prostaglandin E and ten times the thromboxane B2 than do peritoneal cells from normal mice. These results were not due to differences in the ratios of cell subpopulations from each group. As well as providing additional evidence that macrophage activation occtirs in malaria, the increased production of these prostanoids could help explain some of the manifestations of this disease.
AN ULTRASTRUCTURAL STUDY OF MAST CELLS IN THE ALVEOLAR WALL OF NORMAL AND ASTHMATIC LUNG
Authors: Warton A , Papadimitriou JM , Goldie RG , Paterson JW
Published: August 2007

Specimens of normal and asthmatic lungs were studied at the electron microscopic level and the frequency and ultrastructural features of mast cells and their granules within the alveolar wall were assessed with morphometric techniques. The numerical density of mast cells per square millimetre of alveolar wall was 299 (SD = 258) in normal and 366 (SD = 260) in asthmatic lung. The mean area of the mast cell nucleated profile was 25·7 μm2 (SD = 6·3) in normal lung and 29·8 (SD = 6·2) in asthmatic. The average number of secretory granules per single mast cell nucleated profile was 55 (SD = 13) in normal lung and 60 (SD = 12) in asthmatic lung. The diameter of the individual secretory granule was 338·9 nm (SD = 42·6) in normal and 345·6 (SD = 47·7) in asthmatic lung. The volume density of secretory granules in normal and asthmatic lung was 6·31 μm3 and 5·81 μm3respectively. The mean diameter of the individual subunit (“scroll”) inside the secretory granule was 88·8 nm for both normal and asthmatic lung. In normal lung 64·2% of granules were of‘scroll’ and ‘combined’ type, and 35·8% of granules were “particulate” or ‘empty’. In specimens from asthmatic patients 40·3% of granules had ‘scroll’ or ‘combined’ structures and 59·7% were ‘particulate’ or ‘empty’.

Our data suggest that there is no difference between the number of mast cells in normal and asthmatic lung. However, in pulmonary mast cells from asthmatic lung, degranulation is more common than in normal lung.
GROWTH FACTOR‐INDUCED PROLIFERATIVE RESPONSES OF HUMAN AND DMH‐INDUCED RAT COLORECTAL TUMOUR CELL LINES
Authors: Maley MAL , Agrez MV , House AK
Published: August 2007

The proliferative response of three human and three 1,2‐dimethylhydrazine (DMH)‐induced rat colon tumour cell lines to mouse epidermal growth factor (mEGF) and human urogastrone was examined in two in vitro assays (3H‐thymidine uptake in liquid microculture and clonogenicity in semi‐solid medium). In the 3H‐thymidine uptake assay, one of three rat and one of three human colon tumour cell lines, i.e., r237 and LIM1215, were stimulated by mEGF. In the clonogenic assay, mEGF stimulated the one clonogenic rat tumour cell line r113, which did not respond in the 3H‐thymidine uptake assay, and the human tumour cell line LIM1215. Urogastrone stimulated LIM1215 in both assay systems. The significance of these in vitro patterns of response to growth stimulatory factors is discussed.
STIMULATION OF NEUTROPHIL RESPIRATORY BURST AND IODINATION REACTION BY OPSONIZED MICROFILARIAE OF DIROFILARIA IMMITIS
Authors: Rzepczyk Christine M , Bishop CJ , Cheung K , Atwell R , Ferrante A
Published: August 2007

It has been shown that the interaction of Dirofilaria immitis microfilariae (Mf) opsonized with sera from infected but amicrofilaraemic dogs (occult dogs) stimulated the respiratory burst and degranulation of neutrophils as measured by chemiluminescence and iodination. Sera from normal and microfilaraemic dogs gave either low level or non‐significant reactions. Since the sera required were also those required for neutrophil–mediated cytotoxicity to D. immitis Mf in vitro, the results suggested that the products of oxygen reduction as well as the myeloperoxidase system could be involved in the killing of Mf by neutrophils. However, whether these pathways have a major role to play in neutrophil–mediated cytotoxicity to Mf is uncertain, as various chemical and enzymatic inhibitors of the products of the respiratory burst were unable to prevent or reduce cytotoxicity. Azide, which is a known inhibitor of the iodination reaction, also failed to reduce cytotoxicity.
NATURAL DUCK HEPATITIS B VIRUS INFECTION IN AUSTRALIA
Authors: Freiman JS , Cossart YE
Published: August 2007

Natural Duck Hepatitis B Virus (DHBV) infection has been studied in Australian ducks. Sera from 430 Pekin Aylesbury cross‐bred ducks taken from three separate flocks were examined for duck hepatitis B virus (DHBV) DNA using a DNA dot hybridisation assay. In one flock there was significant infection with DHBV (98/140), but none was detectable in the other two flocks. Episomal DHBV DNA in liver tissue was demonstrated by gel blot hybridisation only in birds with DHBV DNA in serum. Polymerase‐labelled DHBV DNA migrated as expected for linear double‐stranded DNA 3·1 kilobase (kb) in length. Virus particles with characteristic DHBV morphology were observed in DHBV DNA‐positive serum on electron microscopy. No overt morbidity has been noted in naturally infected ducks, but moderately severe hepatitis was found in 3/40 ducks examined histologically. These 3 ducks had DHBV DNA in serum and liver tissue. Mild hepatitis was observed in 27 ducks, but, in these, there was no correlation between the hepatitis and the presence of DHBV in serum or in liver tissue. This is the first report of DHBV in Australia. An animal model may now be established to study aspects of Hepadna virus infection which are pertinent to Hepatitis B virus (HBV) disease in man.
COMPARISON OF PROTEINS SPECIFIED BY MURRAY VALLEY ENCEPHALITIS, WEST NILE, JAPANESE ENCEPHALITIS AND ST. LOUIS ENCEPHALITIS VIRUSES
Authors: Wright Peter J , Warr Heather M
Published: August 2007

The relationships among proteins specified by Murray Valley encephalitis (MVE), West Nile (WN), Japanese encephalitis (JE) and St. Louis encephalitis (SLE) viruses were examined by peptide mapping. [3H]methionine‐labelled tryptic peptides of viral proteins were separated by reverse phase high performance liquid chromatography (HPLC) and the separation profiles for a given protein specified by the different viruses were compared. Analyses of the non‐structural protein NV5 (P98 or NS5) suggested that WN and SLE were the most closely related pair of viruses, and that JE was the virus most distant from the other three. Analyses of the structural proteins C and E failed to show the close relationship between WN and SLE indicated by the NV5 results, but did suggest that NV5 was the most conserved and E the least conserved of the three proteins.
LONG TERM EFFECTS OF VASECTOMY ON EXPERIMENTAL ATHEROSCLEROSIS IN RHESUS MONKEYS
Authors: Bansal Neelam , Majumdar S , Ganguly NK , Chakravarti* RN
Published: August 2007

Five groups of male rhesus monkeys, Gp. I–sham‐vasectomized stock diet‐fed (SVS), Gp. II–vasectomized stock diet‐fed (VS), Gp. III–sham‐vasectomized atherogenic diet‐fed (SVA), Gp. IV–vasectomized atherogenic diet‐fed (VA) and Gp. V–atherogenic diet‐fed vasectomized monkeys (AV) were observed for a period of 1½ years. Vasectomy per se had no effect on the level of serum or tissue lipids either alone or in combination with atherogenic diet feeding. Following vasectomy the involvement of aorta by fatty lesions was significantly increased and this occurred in animals of all four experimental groups when compared with the control animals. The maximum increase was noted in group IV. Again, there was a significant increase in the frequency of aortic plaques in groups II, III and IV while it was increased in coronary arteries of all the experimental animals (Gps. II, III, IV and V). Group IV monkeys showed higher frequency of plaques as compared to group V animals. Although the plaque height was increased in all the vessels of the experimental animals, significant differences were observed only in the coronary arteries of group II monkeys and in intra‐cranial cerebral vessels of group III animals. This study shows that vasectomy per se tends to increase atherosclerosis in rhesus monkeys.
PURIFICATION AND PROPERTIES OF LACTATE DEHYDROGENASE FROM PLASMODIUM KNOWLESI AND ERYTHROCYTES OF THE RHESUS MONKEY
Authors: Saxena Nalini , Pandey VC , Dutta GP , Ghatak S
Published: August 2007

Lactate dehydrogenase, E.C.1.1.1.27 (LDH) from the simian malarial parasite, Plasmodium knowlesi, and from normal rhesus monkey erythrocytes has been purified using Blue Sepharose affinity chromatography, and the properties of the purified enzyme from these two sources have been compared.

The enzyme from the host and parasite were different in their kinetic properties, viz., substrate and pH optima, thermostability and isoenzymic behaviour. Partially purified LDH of the erythrocytes resolved into three isomeric bands on polyacrylamide gel electrophoresis, whereas the parasite LDH moved as a single enzyme band of different mobility from the host LDH. The molecular mass of the parasite enzyme was estimated as 117,500 daltons.
GENETIC DIFFERENTIATION OF MURRAY VALLEY ENCEPHALITIS VIRUS IN AUSTRALIA AND PAPUA NEW GUINEA
Authors: Lobigs M , Marshall ID , Weir RC , Dalgarno L
Published: August 2007

The genetic relatedness of ten Murray Valley encephalitis virus (MVE) isolates from Australia has been examined by comparing Haelll and Taql restriction digest profiles of cDNA to virion RNA. The isolates were from the Murray Valley region of south‐eastern Australia and from the Ord River region of Western Australia and spanned a period of 23 years (1951‐1974). The isolates generated closely similar restriction digest profiles. The extent of similarity suggested that the level of nucleotide sequence divergence between any pair of Australian MVE isolates is probably around 1%. The genetic homogeneity of the MVE isolates contrasts with results obtained for Ross River virus, an alphavirus, using an identical methodological approach; we propose that this difference results from the important role of birds in the life cycle of MVE.

Four MVE isolates from three fatal human cases showed small genetic differences on from the other. These isolates did not have a common restriction digest profile which distinguished them from strains obtained from other sources (e.g., from mosquitoes or a heron) The data do not support the view that clinical cases of MVE infection in humans are to a particular strain of virus although this has not been rigorously excluded.

The two available MVE isolates from Papua New Guinea (PNG) were from the Sepik and Port Moresby regions. They generated Haelll and Taql restriction digest profiles which were different both from each other and from those of the Australian type. Genetic divergence between the two PNG isolates was estimated to be ≈ 6%; divergence between either of PNG isolates and the Australian type was >6%. Our data suggest that the evolution of MVE i n Australia and PNG has proceeded independently and that circulating Australian MVE strains are not systematically re‐seeded from regions of endemicity in PNG.

Studies on the relatedness of MVE and two close antigenic relatives, Japanese encephalitis virus (JE) and Alfuy virus (ALF), showed that the genetic relatedness between any isolate and JE or ALF is less than that between the most divergent of the MVE isolates, including those from Papua New Guinea.

Some epidemiologieal implications of the results are discussed.
IMMUNOSUPPRESSION IN MURINE MALARIA: ROLE OF ACTIVATED MACROPHAGES
Authors: Mahajan RC , Ganguly NK , Thadani M , Prasad RN
Published: August 2007

The role of macrophages in immunosuppression which develops during Plasmodium berghei infection in mice has been studied. The transfer of activated macrophages (or their extracts) from the infected mice with low parasitaemia (< 10%) to uninfected mice enhanced their humoral response to sheep red blood cells (SRBC) as indicated by the number of splenic IgM and IgG plaque–forming cells (PFC). In contrast, when macrophages obtained during higher parasitaemia (16%) were used, significant inhibition was observed. These findings indicate that during Plasmodium berghei infection in mice macrophages may play a dual role.
A ROLE OF PULMONARY RAPIDLY ADAPTING RECEPTORS IN CONTROL OF BREATHING
Authors: Davies A , Roumy M
Published: August 2007

We analysed the breathing patter n of anaesthetised rabbits during unloaded breathing when breathing was accelerated by inspired CO2 and when they breathed against positive or negative pressures before and during block of pulmonary stretch receptors by SO2, and after bilateral vagotomy. Before block moderate steps of inflation or deflation (0·5 kPa) produced relatively larger changes in duration of expiration than in duration of inspiration, indicating the relative sensitivities of the two phases. With stretch receptors, blocked inflation or deflation shortened expiration, demonstrating the influence of rapidly adapting receptors on that phase of breathing. If pulmonary stretch receptors were the major determinants of the duration of inspiration, we would have expected inspiratory duration in the stretch receptor blocked and vagotomised states to be almost identical. They were not, inspiratory duration being less in the blocked than in the vagotomised state. Possibly vagal afferent activity other than that of stretch receptors shortens inspiratory duration. However, we have found that rapidly adapting receptor activity (and any unmyelinated fibre activity provoked by rapid inflation or deflation of the lungs) never directly shortened inspiration. We therefore propose a mechanism whereby rapidly adapting receptors may indirectly affect duration of inspiration.
10th Meeting of the Society for Natural Immunity, Cambridge, UK, 11–14 April 2007
Authors: Huntington Nicholas D
Published: August 2007

Natural killer (NK) cells are important members of the innate immune system being involved in the detection and clearance of transformed or virus‐infected cells. The 10th meeting of the Society for Natural Immunity was recently held in Cambridge, UK, where leaders from around the globe gathered to discuss the latest developments and understandings in the field of NK cell biology. Among the topics covered in this meeting were NK cell development, the origin of thymic NK cells, contribution of NK cells to viral infections and subsequent tissue damage, crosstalk between NK cells and other immune cells and the role of NK cells at the foetal–maternal interface.
Ab initio study of the reaction of propionyl (C2H5CO) radical with oxygen (O2)
Authors: Hou Hua , Wang Baoshan
Published: August 2007

The reaction of propionyl radical with oxygen has been studied using the full coupled cluster theory with the complete basis set. This is the first time to gain a conclusive insight into the reaction mechanism and kinetics for this important reaction in detail. The reaction takes place via a chemical activation mechanism. The barrierless association of propionyl with oxygen produces the propionylperoxy radical, which decomposes to form the hydroxyl radical and the three-center α-lactone predominantly or the four-center β-propiolactone. The oxidation of propionyl radical to carbon monoxide or carbon dioxide is not straightforward rather via the secondary decomposition of α-lactone and β-propiolactone. Kinetically, the overall rate constant is almost pressure independent and it approaches the high-pressure limit around tens of torr of helium. At temperatures below 600K, the rate constant shows negative temperature dependence. The experimental yields of the hydroxyl radical can be well reproduced, with the average energy transferred per collision −⟨ΔE⟩=20–25cm−1 at 213 and 295K (helium bath gas). At low pressures, together with the hydroxy radical, α-lactone is the major product, while β-propiolactone only accounts for about one-fifth of α-lactone. At the high-pressure limit, the production of the propionylperoxy radical is dominant together with a fraction of the isomers. The infrared spectroscopy or the mass spectroscopy techniques are suggested to be employed in the future experimental study of the C2H5CO+O2 reaction.
Unraveling the structure of hydrogen bond stretching mode infrared absorption bands: An anharmonic density functional theory study on 7-azaindole dimers
Authors: Dreyer Jens
Published: August 2007

The structure of the linear infrared absorption spectrum of the N–H stretching mode in 7-azaindole dimers is analyzed by quartic anharmonic vibrational force field calculations based on density functional theory. It is demonstrated that a multiple Fermi resonance model including contributions from 12 fingerprint vibrational modes, most of them containing considerable contributions of N–H bending motions, combined with a single low-frequency mode satisfactorily explains the complex line shape of N–H stretching mode absorption band.
High resolution vacuum ultraviolet emission spectrum of D2: The B′Σu+1→XΣg+1 band system
Authors: Roudjane Mourad , Tchang-Brillet W.-Ü Lydia , Launay Françoise
Published: August 2007

In this work, we have extended our previous high resolution study of the vacuum ultraviolet emission spectrum of the D2 molecule [M. Roudjane, et al. J. Chem. Phys. 125, 214305 (2006)] up to 124.2nm in order to investigate the B′Σu+1→XΣg+1 band system. The analysis of the spectrum has been carried out by means of a complex spectrum visual identification code IDEN [V. I. Azarov, Phys. Scr. 44, 528 (1991); 48, 656, (1993)] and supported by theoretical calculations using ab initio data [L. Wolniewicz, J. Chem. Phys. 103, 1792 (1995); 99, 1851 (1993); G. Staszewska and L. Wolniewicz, J. Mol. Spectrosc. 212, 208 (2002); L. Wolniewicz and G. Staszewska, 220, 45 (2003)] which provided level energies and transition probabilities. More than 1480 new emission lines have been observed and 109 bands belonging to the B′Σu+1→XΣg+1 system have been identified between 84.1 and 121.6nm. Except for the υ′−0 bands that were reported in absorption [I. Dabrowski and G. Herzberg, Can. J. Phys. 52, 1110 (1974)], all the υ′−υ″ bands are reported here for the first time. The analysis led to the determination of 111 rovibronic energy levels in the B′Σu+1 state, of which 31 with higher rotational numbers J are new. Observed perturbations are accounted for through a set of coupled equations involving the four excited electronic states BΣu+1, B′Σu+1, CΠu1, and DΠu1 and including nonadiabatic couplings. The solution of this set provides the percent contribution of these four states to each of the observed rovibronic level.
Precise atomic force microscope cantilever spring constant calibration using a reference cantilever array
Authors: Gates Richard S. , Reitsma Mark G.
Published: August 2007

A method for calibrating the stiffness of atomic force microscope (AFM) cantilevers is demonstrated using an array of uniform microfabricated reference cantilevers. A series of force-displacement curves was obtained using a commercial AFM test cantilever on the reference cantilever array, and the data were analyzed using an implied Euler-Bernoulli model to extract the test cantilever spring constant from linear regression fitting. The method offers a factor of 5 improvement over the precision of the usual reference cantilever calibration method and, when combined with the Système International traceability potential of the cantilever array, can provide very accurate spring constant calibrations.
Enhanced flow in smooth single-file channel
Authors: Roy Majumder Shashwati , Choudhury Niharendu , Ghosh Swapan K.
Published: August 2007

We investigate the flux of particles in a smooth single-file channel where particles cannot cross each other as well as in wider channels of varying cross section where particles execute normal diffusion. All the channels are connected to an infinite reservoir at one end and the flux of particles is measured at the other open end. We perform random walk Monte Carlo simulation using lattice model. The flux decreases monotonically as the channel cross section is increased from single-file channel to wider channel and finally reaches a constant value for a sufficiently wide channel. The observation of enhanced flux in single-file channel as compared to a wider channel can be tested for efficient separation of particles through smooth nanochannels.
Extraordinary transmission through a silver film perforated with cross shaped hole arrays in a square lattice
Authors: Chen Chia-Yi , Tsai Ming-Wei , Chuang Tzu-Hung , Chang Yi-Tsung , Lee Si-Chen
Published: August 2007

In this work, the transmission through cross shaped hole with different sizes but the same lattice constant was measured with the polarized light to investigate the variation of localized charge oscillation around the hole. The comparison between the transmission intensities through the similarly arranged periodic hole array with different hole shapes, i.e., cross, square, and rectangular, were also measured. The cross shaped hole gives rise to a larger transmission of light than those perforated with square or rectangular hole.
Transverse rectification in superconducting thin films with arrays of asymmetric defects
Authors: Gonzalez E. M. , Nunez N. O. , Anguita J. V. , Vicent J. L.
Published: August 2007

Superconducting Nb films have been grown on top of arrays of Cu nanotriangles. These asymmetric pinning centers strongly modify the vortex lattice dynamics. Two rectification effects have been observed: (i) longitudinal ratchet effect when the input currents are injected perpendicular to the triangle reflection symmetry axis and (ii) transverse rectification effect when the input currents are injected parallel to the triangle reflection symmetry axis and the output voltage drop occurs perpendicular to the triangle reflection symmetry axis. Increasing the applied magnetic field, the former shows a change of the output voltage polarity, the transverse output voltage does not show any polarity reversal.
Local modification of electronic structure of Si (111)-7×7 surfaces by forming molybdenum-encapsulating Si clusters
Authors: Uchida Noriyuki , Yahata Hiroshi , Kanayama Toshihiko , Bolotov Leonid
Published: August 2007

Using scanning tunneling microscopy, the authors show that uniform-size Mo-encapsulating Si clusters, MoSin, were synthesized on Si (111)-7×7 surfaces by the reaction between SiH4 and Mo atoms deposited on the surface followed by thermal annealing at 600°C. Comparing observed images with ab initio structure calculations indicates that n=6. According to scanning tunneling spectroscopy measurements, the MoSin cluster has a semiconducting energy gap of approximately 0.3eV, indicating that the metallic electronic state of the 7×7 surface can be locally modified by formation of the MoSin cluster.
Widely tunable 2.3 μm-band difference frequency generation in quasiphase-matched LiNbO3 ridge waveguide using index dispersion control
Authors: Tadanaga Osamu , Yanagawa Tsutomu , Nishida Yoshiki , Magari Katsuaki , Umeki Takeshi , Asobe Masaki , Suzuki Hiroyuki
Published: August 2007

We describe widely tunable 2.3 μm difference frequency generation in direct-bonded quasiphase-matched (QPM)-LiNbO3 (LN) ridge waveguides by controlling the refractive index dispersion. We calculate the phase matching characteristics of waveguides with various core areas for a fixed pump wavelength of 0.934 μm and show that a larger core area results in a wider signal tuning range in the 1.55 μm band. Based on the calculation, we fabricate QPM-LN ridge waveguides with two different waveguide core sizes. A wide tuning range of over 173 nm with a conversion efficiency of 56%/W is demonstrated in the 2.3 μm range using the waveguide with the larger core size. We also carry out CO gas measurements using a signal wavelength in the telecommunication band and detect 44 lines of the CO absorption owing to the wide tuning range and efficient conversion efficiency of the waveguide.