bluuebunny/crossref_metadata_2025 huggingface dataset:
Pseudechinoparyphium echinatum (Digenea: Echinostomatidae): experimental observations on cercarial specificity toward second intermediate hosts
Authors: McCarthy A. M. , Kanev I.
Published: June 2009

Infectivity of Pseudechinoparyphium echinatum cercariae to 11 species of gastropod was examined experimentally. Broad specificity and differential host—parasite compatibility were exhibited. Nine gastropod species functioned as second intermediate hosts. Planorbarius corneus, Physa fontinalis, Lymnaea peregra and Biomphalaria alexandrina showed high levels of compatibility with the parasite. In single-species exposures over 90% of cercariae encysted in each of these hosts. Low compatibility with the first intermediate host species Lymnaea stagnalis may be a mechanism preventing super-infection of emitting snails. Cercariae did not infect the prosobranchs Bithynia tentaculata and Viviparus viviparus. Experimental infection of a host community comprised of 8 European gastropod species revealed an order of host utilization similar to that shown in single-species exposures. However, cercarial transmission success in P. fontinalis and L. peregra (compared to that in P. corneus) was significantly reduced. This may have been due to the marked preference to cercariae for P. corneus compared to the other two highly suitable hosts for whom cercariae showed equal preference.
Studies on infection and reinfection by eugregarines
Authors: Harry Owen G.
Published: June 2009

Reinfection of the insects Tenebrio molitor and Schistocerca gregaria by the Eugregarines Gregaria polymorpha and G. garnhami respectively is not caused by the retention of the gametocyst and the release of sporocysts inside the gut. The gametocyst has to pass out from the insect gut, dehisce, and the sporocysts have to be ingested in order for reinfection to occur. Thus it is possible to stop reinfection by preventing the host from ingesting sporocysts. The development of spore ducts on the gametocyst of G. garnhami is inhibited if the gametocysts are prevented from leaving the hindgut of the locusts.

I would like to thank Professor L. H. Finlayson for his advice for many helpful discussions.
Effects of different levels of nutrition and continuing dosing of poultry with Ascaridia galli eggs on the subsequent development of parasite populations
Authors: Ikeme M. M.
Published: June 2009

The population dynamics of Ascaridia galli infections of poultry was studied under repeated doses of 10, 100 and 1000 eggs. Daily doses were continued for 6 weeks only. At low dose rates patency is noted by the fifth week. At higher dose rates there is an accumulation of larvae whose development has been arrested at a precise developmental stage, i.e. the third larval stage. Sporadic development of some of these larvae to adults occurs later. Arguments are produced to show that this inhibition of larval development is a resistance and not a density-dependent phenomenon. The epidemiological significance of this inhibition is discussed. This resistance phenomenon is shown to occur in single infection experiments where 1000 eggs were used. This gives rise to the development of a worm population of two facies. The whole finding is suggested to be related in some way to the phenomenon of ‘tissue phase’, which is accepted as a normal life-cycle behaviour of this parasite. A brief review of previous work on this is given and it is postulated that the ‘tissue phase’ phenomenon is not an obligatory part of the normal life-cycle of the parasite but represents a reaction to factors of resistance inherent in chickens and controlled to a large extent by a complex dynamic interplay of dose size and the chickens.

I wish to thank the Department of Technical Co-operation and the Federal Government of Nigeria for financing this project, Dr Boulton of the Poultry Research Centre, Edinburgh, for advice on nutrition, and the Department of Zoology, especially Dr J. A. Campbell, University of Edinburgh, for facilities and advice on the work. I am greatly indebted to the Ministry of Agriculture, Fisheries and Food, Poultry Research Laboratories, Lasswade, for the free supply of chickens used in this work.
Variations in the fecundity of strongylid worms of the horse
Authors: Ogbourne C. P.
Published: June 2009

A large proportion of Strongylus vulgaris, S. edentatus and Trichonema nassatum collected from the gut lumen of slaughtered horses during the winter did not contain eggs. The proportion of Trichonema catinatum without eggs declined to a low level during the winter and rose to relatively high levels during the summer, It has been concluded that worms without eggs are newly matured individuals and that seasonal variations in fecundity reflect similar fluctuations in the age distribution of the adult populations. These fluctuations are related to seasonal differences in the numbers of infective larvae ingested and to the length of parasitic development.Most Strongylus vulgaris, S. edentatus and Trichonema nassatum reach the adult stage during the winter and it has been suggested that an increase in worm numbers during this period is responsible for a rise in the faecal egg counts of horses in the spring. The observations on T. catinatum indicate that the level is maintained by the arrival of new individuals during the summer.

I wish to thank Dr H. D. Crofton for his constant advice and encouragement during this work and Professor H. E. Hinton, F.R.S., for the provision of laboratory facilities. I am indebted to Mr L. J. Potter for allowing me to collect the parasites from his slaughterhouse at Bishop Sutton, near Bristol. This work was carried out during a research studentship funded by the Horse Race Betting Levy Board.
The effect of density of first-stage larvae of Elaphostrongylus rangiferi on the infection rate in the snail intermediate host
Authors: Skorping Arne
Published: June 2009

The relationship between the density of lst-stage larvae of Elaphostrongylus rangiferi on the infection rate into the gastropod intermediate host, Arianta arbustorum, was studied experimentally. Within a range of densities between 30 and 1100 larvae/cm2 the experimental data gave a good fit to the conventional epidemiological assumption of direct proportionality between the net infection rate and the density of infective stages. The instantaneous rate of infection was estimated to be about 1 × 10−3/larvae/snail/2 h. At higher densities (> 1100 larvae/cm2) the instantaneous rate of infection showed a densitydependent decline.
Cercaria vaullegeardi Pelseneer, 1906 (Digenea: Hemiuridae); the infection mechanism
Authors: Matthews B. F.
Published: June 2009

The inoculative mechanism whereby cystophorous cercariae infect the copepod 2nd intermediate host is described for the first time in Cercaria vaullegeardi. Experimental infections of the harpacticoid copepod Tigriopus brevicornis are recorded and the infection process is related to the ultrastructure of the cercaria and to the feeding mechanics of harpacticoids. The cystophorous tail of C. vaullegeardi is shown to be a device whose shape and construction ensure that the cercarial body is neither damaged by copepod mouthparts nor swallowed, but reaches the host haemocoel during the initial stages of feeding. The cystophorous tail consists essentially of a caudal cyst, into which the cercarial body retracts at encystment, and various appendages including a delivery tube. The infection mechanism is triggered when the copepod mandibles bite the narrow posterior caudal cyst beak, when the delivery tube everts into the mouth and penetrates the dorsal mid-gut wall. The cercarial body, lubricated by tegumental secretions, passes simultaneously through the delivery tube and is inoculated into the host haemocoel.
A putative Leishmania panamensis/Leishmania braziliensis hybrid is a causative agent of human cutaneous leishmaniasis in Nicaragua
Authors: Belli A. A. , Miles M. A. , Kelly J. M.
Published: June 2009

As part of a survey of human leishmaniasis in Nicaragua we examined phenotypic and genotypic characteristics of 40 Leishmania isolates. We identified 3 distinct parasites associated with cutaneous disease in this area; Leishmania panamensis (40% of cases), Leishmania braziliensis (33%), and a strain which exhibits the heterozygous isoenzyme and DNA fingerprinting patterns expected of a L. panamensis/L. braziliensis hybrid (27%). There was complete correlation between the isoenzyme and DNA data for each of the putative hybrids examined. All of the ‘hybrids’ were obtained from foci in the northern region of the country where L. panamensis and L. braziliensis occur sympatrically. These observations provide strong evidence for sexual reproduction in New World Leishmania populations and suggest that it is of taxonomic and epidemiological significance.
Immune response profiles in vaccinated and non-vaccinated high- and low-responder mice during infection with the intestinal nematodeTrichinella spiralis
Authors: Robinson K. , Bellaby T. , Wakelin D.
Published: June 2009

NIH and C57 BL/10 (BIO) mice show genetically determined differences in their response toTrichinella spiralisinfection. This study examines the influence of these on parameters of the immune response to infection after vaccination using muscle-larval excretory–secretory antigen in Freund's complete adjuvant. Serum antibody levels were greatly elevated when mice of both strains were vaccinated prior to infection; however, NIH produced significantly higher-level antibody responses than B10. Vaccination accelerated and increased the capacity of mesenteric lymph node T-cells to proliferatein vitroin response to specific antigen stimulation in both mouse strains but, in general, the stimulation indices of NIH cells were higher than those of the B10. The capacity of mesenteric lymph node cells (MLNC) and spleen cells (SC) to produce IL-5 and γIFN was measured after specificin vitrostimulation and early γIFN secretion was noted in the supernatants of NIH MLNC and SC, but not in B10 SC. Concentrations of IL-S rose steadily over the first 10–14 days after infection in cell cultures from both strains. Prior vaccination of these animals appeared to enhance cytokine levels. It is postulated that the efficacy of vaccination in NIH mice is a consequence of their genetically determined capacity to produce early and high-level responses to the antigens ofT. spiralisand to express these in intestinal effector mechanisms.
The ultrastructural localization of Echinococcus granulosus antigen 5
Authors: Jones M. K. , Zhang L.-H. , Leggatt G. R. , Stenzel D. J. , McManus D. P.
Published: June 2009

Murine monoclonal and polyclonal antisera, raised against the 38 kDa subunit of Echinococcus granulosus antigen 5, were used to investigate the tissue distribution of the antigen in hydatid cysts. Immunoreactivity was visualized by indirect immunofluorescence on whole protoscoleces, and ultrastructural immunocytochemistry utilizing colloidal gold-based labelling procedures on unsectioned and cryosectioned brood capsules and protoscoleces. In protoscoleces, the 38 kDa subunit of antigen 5 was localized at the interface of parenchymal cells and associated extracellular matrices, as well as along the interface of the tegumentary syncytium in the somal region and its basal matrix. Cytoplasmic labelling of parenchymal cells was rare; when observed, it was associated with vesicles and membranes in cytoplasmic extensions of parenchymal cells. In brood capsules, the antigen was associated with the external face of the plasma of degenerating parenchymal cells. The 38 kDa subunit occurs along the extracellular face of cell membranes, suggesting that antigen 5 is either a component of the membranes or associated extracellular matrices.
Factors influencing infections in Rhipicephalus appendiculatus ticks fed on cattle infected with Theileria parva
Authors: Young A. S. , Dolan T. T. , Morzaria S. P. , Mwakima F. N. , Norval R. A. I. , Scott J. , Sherriff A. , Gettinby G.
Published: June 2009

A large database on the transmission of a stabilate of the Theileria parva Muguga stock from one breed of cattle using two stocks of Rhipicephalus appendiculatus, Muguga and Ol Pejeta was developed and analysed. Factors associated with the ticks and cattle, and the infections developing in cattle were studied in relation to the infection variables in the tick batches harvested daily from cattle. Generalized Linear Interactive Modelling (GLIM) was used to determine the importance of factors and interactions in influencing the levels of tick infection variables using Type I and Type III sums of squares analyses. Analysis of the 6 variables, prevalence (percentage of ticks infected), abundance (mean number of infected salivary gland acini per tick examined) and intensity (mean number of infected salivary gland acini per infected tick) in batches of 30 male and 30 female ticks showed that 24 covariates, factors or interactions had a significant effect (P> 0·05). Certain covariates and factors were particularly important for all 6 tick infection variables; parasitaemia of animal on the day of tick harvest, stabilate dilution administered to animal, month in which tick batch was harvested, minimum packed cell volume of animal over the sampling period, age of animal, and the minimum leukocyte count of the animal over the sampling period. The GLIM analyses were found to be a useful tool in identifying factors that influence infection levels and in devising methods of producing tick batches with more predictable infections.
Transmission of histomoniasis with male Heterakis gallinarum (Nematoda)
Authors: Springer W. T. , Johnson Joyce , Reid W. M.
Published: June 2009

Histomoniasis was transmitted to poults inoculated orally with recently harvested whole intact male worms in three trials (4/5, 5/6, 2/4), but not with female worms (0/5, 0/9, 0/3). When triturated male worms were given in two trials, the rate of transmission was reduced (3/5, 0/10). Triturated female worms given orally produced histomoniasis in 1/9 poults. These results suggest that further unknown steps may be involved in histomonad transmission by heterakid worms.

This study was partially supported by NSF Grant GB-5227.
The morphology and life cycle ofProtopolystoma xenopi(Price) Bychovsky in Uganda
Authors: Thurston June P.
Published: June 2009

1.The morphology ofProtopolystoma xenopifrom Uganda is compared with specimens previously described by Williams. The chief differences are the slightly greater maximum size, the presence of a second pair of anchors on the opisthaptor, and the absence of a second large oviducal chamber in the uterus.

2. Encapsulation of the egg is described from living worms. A thin, plastic membrane forms around the ovum and yolk cells within the ootype before all the yolk cells have passed into the ootype. The remaining yolk cells pass from the ovo-vitelline duct into the sac formed by this membrane, which is attached to the distal walls of the ootype.

3. Eggs are produced at the rate of 4–15 eggs/worm/24 hr. They hatch in 24–27 days at 24–26° C. The opisthaptor of the larva bears sixteen hooklets and two pairs of anchors, which are in the same positions as in the adult.

4. One larva with one pair of suckers was obtained from the alimentary canal or kidney of a metamorphosingXenopustadpole. About sixty other tadpoles were examined forP. xenopibut none was found.

5. TwelveP. xenopiwere recovered from the kidneys of a small frog that had been infected experimentally 10 days previously.

6. When naturally infected small frogs from Kajansi Fish Farm were examined, immatureP. xenopiwere found in the kidney of one frog, in the urinary ducts of two frogs, and in the bladder of one frog. The infection rate was much lower than that in matureXenopus. ImmatureP. xenopiwere also found in the kidneys of matureXenopus mülleri.

7.P. xenopimatures more rapidly than its host. A frog weighing only 2·9 g. contained a nearly mature worm in the bladder, while one weighing 4·2 g. contained two mature worms, shedding eggs. Eggs are shed throughout the year. The life cycle ofP. xenopiis therefore not regulated by that of its host.
A simple apparatus for harvesting infective stage nematodes emerging from their insect hosts
Authors: Carne P. B. , Reed E. M.
Published: June 2009

A simple but efficient apparatus for harvesting nematodes migrating from their insect hosts is described. Infected host larvae are supported, in contact with water, on a nematode-permeable diaphragm resting in the mouth of a large funnel. A battery of funnels can be connected in series and their water-level maintained by a common constant-level device.
Properties of red cell ghost preparations susceptible to invasion by malaria parasites
Authors: Dluzewski A. R. , Rangachari K. , Wilson R. J. M. , Gratzer W. B.
Published: June 2009

Experimental procedures are described that lead to the formation of sealed red cell ghosts capable of efficient invasion by malaria parasites. Both human and monkey cells have been studied with respect to invasion byPlasmodium falciparumandP. knowlesirespectively. Resealed ghosts containing about half the normal concentration of haemoglobin are prepared by osmotic lysis and resealing at a haematocrit of 70%. When examined in the scanning electron microscope, populations of these ghosts contain few echinocytes, but have an abundance of stomatocytic forms. When undiluted haemolysate is substituted for the aqueous saline diluent, in which the cells are suspended for lysis and resealing, discocytes result, with a morphology very similar to that of the original cells. Invasion is somewhat, but not dramatically higher for this material. An investigation of the effect of intracellular potassium concentration revealed that this had no major effect on invasion. A small increase in invasion resulted from addition of 50 or 100 mg/ml of albumin to the medium in which the cells were resealed, but intra-erythrocytic protein contentper seis evidently not a major factor in determining the efficiency of invasion. Augmentation of the cytoplasmic ATP concentration during lysis and resealing increased the level of parasitaemia significantly, and the parasites in these ghosts developed normally and gave rise to viable merozoites. It was found that albumin at certain concentrations passed freely into the lysed cells and reached equilibrium with that in the external medium. By contrast, the high molecular weight solute Blue Dextran 2000 was completely excluded from the lysed cells.
Nature and nurture: overcoming constraints on immunity
Authors: Wakelin D.
Published: June 2009

Parasitic infections in man and domestic animals exhibit two striking characteristics (a) their prevalence is high, but infections are unequally distributed among individuals within populations and (b) immunity is often slow to develop and appears, at best, only partially effective. Recent immunological and epidemiological studies suggest that effective immunity can develop, but that high prevalence within populations reflects the operation, not only of socio-economic and climatic factors, or husbandry practices, but also of powerful environmentally induced constraints upon the development of resistance. Immunogenetic studies suggest the operation of additional constraints which reflect individual genetic characteristics, and which influence the ability to develop and express effective immunity. A full understanding of all constraints is necessary before levels of population and individual resistance to infection can be increased; the need for such understanding has become more pressing with the prospect that anti-parasite vaccines may become available. Two aspects of environmentally induced constraints are considered, those arising from nutritional inadequacies and those resulting from exposure to infection in early life. Both are discussed primarily in terms of helminth parasites. Genetically determined constraints are discussed with reference to MHC-restricted recognition of malarial peptide vaccines and in terms of Class II molecule-directed control of T-cell function inLeishmaniainfections. Genetic influences are also considered from the standpoint of inflammatory cell function, in immunity against intestinal nematodes and in vaccine-induced immunity againstSchistosoma. Finally, parasite-induced constraints, particularly those which down-regulate protective responses are discussed briefly.
The ecology of immature phases of trichostrongyle nematodes
Authors: Crofton H. D.
Published: June 2009

Observations on the larvae of sheep trichostrongyles on hill pastures showed:

1. A reduction in larval populations occurred when the ‘moving-flock’ type management was used. The large proportion of eggs passed in faeces is deposited on a part of the pasture where little or no grazing occurs.

2. Local concentrations of larvae occurred on the grazed portions of a pasture when grazing was uneven. Thus, the apparent low rate of stocking on hill pastures does not give a true picture of the potential dangers of parasitic disease. Estimates of pasture contamination by Taylor's method of sampling were deceptively low.

3. The number of larvae on grass blades was lowest when the grass was wet with dew. Sampling of pastures between 12 noon and 5 p.m g.m.t. gave maximal and most constant estimates.

4. There was an increase in the number of larvae on a pasture during the warmer months of the year. While low temperatures prevent or delay hatching, the increase in population was not entirely due to the increased rate of development when temperature was high. The increase in numbers was partly due to an increase in the number of adult worms in the sheep hosts.

5. Removal of sheep for 3 weeks reduced the number of larvae on a pasture. This reduction was not apparent, however, until after the first 12 days. After 3 weeks the pasture population was reduced by 55 %, while after 4 weeks (i.e. 7 days after the return of the sheep) the reduction was 90%. Two weeks later there was a small increase in the larval population, but this was again reduced with the onset of colder conditions.
Studies on the lung nematodes of sheep and goats in the Levant
Authors: Gerichter Ch. B.
Published: June 2009

Five species of lung nematodes of sheep and goats were found in the Levant countries, namely: Dictyocaulus filaria, Cystocaulus ocreatus, Muellerius capillaris, Protostrongylus rufescens and Neostrongylus linearis. Cystocaulus ocreatus is the commonest, while Neostrongylus linearis is very rare. Descriptions of the morphology of the adults and of all the developmental stages of all these species, except the last, are presented. The presence of a small but well-developed bursa of a protostrongylid type in Muellerius capillaris has been established. The life histories of Cystocaulus ocreatus, Muellerius capillaris and Protostrongylus rufescens have been studied and the susceptibility of various snail hosts has been determined. Experimental infections with larvae of Cystocaulus ocreatus and Muellerius capillaris have been induced in eleven species of terrestrial snails and slugs (belonging to seven genera). Only three of these eleven species proved susceptible to infection with larvae of Protostrongylus rufescens. Experimental infections of definitive hosts with these three species have been obtained. Lowering the temperature retards larval development in the snail. The larval development of P. rufescens is especially retarded and its larvae do not develop at all at temperatures lower than 4–8° C. Natural infection of Helicella barbesiana with the larvae of Cystocaulus ocreatus, Muellerius capillaris and Protostrongylus rufescens has been found in the vicinity of Jerusalem.
Pamaquin Resistance in a Strain of Plasmodium gallinaceum and its relationship to Other antimalarial Drugs
Authors: Bishop Ann , McConnachie Elspeth W.
Published: June 2009

1. A four- to eight-fold increase in resistance to pamaquin has been developed in a strain of Plasmodium gallinaceum in chicks.

2. Pamaquin resistance conferred no resistance to proguanil, sulphadiazine, mepacrine, chloroquine or sontochin, but it conferred some resistance to pentaquine and to quinine.

3. An appreciable loss in resistance to pamaquin was observed in the pamaquin-resistant strain after it had been maintained in the absence of the drug, in a patent state of infection, for a period of 6 months.

4. No synergism was observed between pamaquin and quinine when these drugs were tested, in combined doses, upon active infections of P. gallinaceum.
A sporozoan blood parasite of Archiulus moreleti (Diplopoda)
Authors: Gibbs Alfred J.
Published: June 2009

The blood parasite described in this paper occurs in the diplopod Archiulus moreleti (the common garden milliped) which is too well known to warrant any description. The incidence of the infection fluctuates considerably, varying from almost 50% to about 1% in the same locality within the course of a few months. There is apparently no seasonal rhythm of incidence.
The capitulum and feeding mechanism ofIxodes hexagonusLeach. II
Authors: Arthur D. R.
Published: June 2009

1. The action of the mouthparts ofIxodes hexagonusduring the penetration of artificial membranes is described.

2. Above the hypostomal groove, the chelicerae are closely apposed in the mid-line, but on the inner lower surface each inner cheliceral sheath is drawn into a ventral, toothed lobe, which overlies the hypostomal groove. This lobe disappears in front of the labro-hypostomal groove.

3. A lamellate mass of homogeneous material surrounds the rostrum in the skin and at the tip of the hypostome there is marked cytolysis of the dermal cells. There are some pyknotic nuclei visible in this region, and the endothelial walls of the capillaries are swollen, and some contain many polymorphs.
Problems of nomenclature for the growth of organisms of one species with and without associated organisms of other species
Authors: Dougherty Ellsworth C.
Published: June 2009

A recent editorial in Nature (Anon., 1951) on current problems in parasitology has emphasized the importance of the cultivation of parasitic organisms free from their hosts and from other species. The increased interest of workers in this type of problem, and their expanded efforts with helminths (as reviewed by Read, 1950, for helminths in general, and by Hobson, 1948, for the nematodes), which have so far almost completely resisted in vitro cultivation through whole life cycles,‡ make highly desirable an assessment of the nomenclature to be used in describing various relationships between organisms, both in nature and in the laboratory.
Radioactive labelling experiments with Plasmodium
Authors: Kuper S. W. A. , Pelc S. R.
Published: June 2009

An account is given of the methods used to produce radioactive oocysts of P. gallinaceum. The latter are demonstrated in stained sections and in autoradio-graphs. The photographs show oocysts in mosquitoes fed on solutions of radioactive phosphorus and radioactive sulphur.
The development of resistance to metachloridine inPlasmodium gallinaceumin Chicks
Authors: Bishop Ann , McConnachie Elspeth W.
Published: June 2009

1. An increase in resistance to metachloridine of more than 100-fold was obtained within a few weeks in a strain ofPlasmodium gallinaceumtreated with gradually increasing doses of the drug and maintained in young chicks by blood-inoculation at intervals of 2–3 days.

2. There was no evidence that the rapid development of resistance arose by the selection of highly resistant individuals present in the normal population.

3. Two strains ofP. gallinaceumpassaged through chicks treated with 0·025 mg. doses of the drug gradually became resistant to greater concentrations than that to which they had been exposed, though their growth rate decreased when they were inoculated into birds receiving higher doses of the drug.

4. In both strains maintained in birds treated with 0·025 mg. doses of the drug, resistance reached a maximum beyond which it did not increase.

5. Cross-resistance tests failed to show any relationship in mode of action between meta-chloridine and pamaquin, mepacrine, quinine or chloroquine. A strain ofP. gallinaceum, highly resistant to metachloridine, showed slight resistance to sulphadiazine, sulphapyridine and sulphathiazole, but none to sulphanilamide or proguanil.

We are indebted to the Cyanamid Products Ltd., London, for the gift of the Folvite used in these experiments.
Limits, Perspectives, and Thought
Authors: Shand John
Published: June 2009

Imagine a universe without human beings. Now imagine a universe devoid of any creatures like human beings, beings who could think about the universe and in so doing consider it as divided up into different kinds of things that could be objects of understanding. Now imagine – this is harder – your not being there, or anyone else, to imagine such a universe. Next think about setting about describing in physical laws such a universe in line with a completist physicalist program: that all the facts about the world are physical facts. But where would one begin? Why would one begin? Remember there is no-one around to take more interest in any part of the universe than any other. This contrasts with what we do now. What we do now is take chunks of the universe – stars, planets, water, trees, air, particles – and demarcate the physical laws in such a way as to explain how these objects behave against a background of other objects and ultimately the universe as a whole. But what if we were not around? Why would we there be any reason to demarcate groups of physical laws in this or any other way? My suggestion is that there would be none. The grouping of the physical laws to form complex classes and layers of explanations (how trees and water are related; how planets move as part of a solar system) is parasitic upon creatures having particular interests giving them a perspective (‘perspective’ is being used here in a somewhat technical sense) upon the universe or world, which in turn derives from the kind of limited creatures they happen to be. But the perspective itself is not a physical fact about the universe. Rather it is a way of coming to form a system of facts about the universe. Further, not only might the perspective have been otherwise, there might be none at all. In which case the demarcation of physical laws, given meaning by their application to entities picked out as having a certain significance to us, would not get off the ground. At best there might be a random bunching of laws covering regions of the universe. But such random bunchings would have no meaning; they would be unintelligible; they wouldn't really be about anything. For laws to be about things you have to have limited creatures who differentiate between parts of the universe, and for whom different parts have a variable significance and value. Things stand out for them; they literally exist. Without such creatures, things we take for granted would, in the literal sense, not exist. It is the very limitedness of our perspective and capabilities, such that things are problems for us, and wherefore we literally or metaphorically bump into things, that brings objects into existence for us. Otherwise the universe would be utterly ‘flat’ and undifferentiated. A limitation of perspective is required for there to be objects of thought, and thus for thought itself. Thus, the intelligibility of the laws of physics is logically parasitic upon our having varying interests in different segments of the universe.
Ion heating resulting from pickup in magnetic reconnection exhausts
Authors: Drake J. F. , Swisdak M. , Phan T. D. , Cassak P. A. , Shay M. A. , Lepri S. T. , Lin R. P. , Quataert E. , Zurbuchen T. H.
Published: May 2009

The heating of ions downstream of the x‐line during magnetic reconnection is explored using full‐particle simulations, test particle simulations, and analytic analysis. Large‐scale particle simulations reveal that the ion temperature increases sharply across the boundary layer that separates the upstream plasma from the Alfvénic outflow. This boundary layer, however, does not take the form of a classical switch‐off shock as discussed in the Petschek reconnection model, so the particle heating cannot be calculated from the magnetohydrodynamic, slow‐shock prediction. Test particle trajectories in the fields from the simulations reveal that ions crossing the narrow boundary into the exhaust instead behave like pickup particles: they gain both a directed outflow and an effective thermal speed given by the flow speed v0 of the exhaust. The detailed dynamics of these particles are explored by taking 1‐D cuts of the simulation data across the exhaust, transforming to the deHoffman‐Teller frame, and calculating explicitly the increment in the temperature, miv02/3, with mi, the ion mass. We compare the model predictions with the temperature increment in solar wind exhausts measured by the ACE and Wind spacecraft, confirming that the temperature increment is proportional to the ion mass. The Wind data from 22 high‐shear exhaust encounters confirm the scaling of the proton temperature increment with the square of the exhaust velocity. However, the temperature increments are consistently lower than the model prediction. Implications for understanding the production of high‐energy ions in flares and the broader universe are discussed.
Ionospheric effects on GPS signals in the Arctic region using early GPS data from Thule, Greenland
Authors: El‐Arini M. B. , Secan J. , Klobuchar J. A. , Doherty P. H. , Bishop G. , Groves K.
Published: May 2009

Thule, Greenland, is near the magnetic North Pole, and therefore any high‐speed GPS data recorded there are of great potential import in specifying the severity of ionospheric effects on modern commercial navigation and ranging systems that must transit the polar latitudes. While there have now been many sets of GPS receiver data recorded at high latitudes, including GPS‐IGS data routinely taken from Thule, Greenland, virtually all of these data have not been recorded at a high enough rate to measure the actual amplitude and phase scintillation effects. One notable exception is very early data taken from Thule, in the late 1980s and early 1990s, a period of high solar activity where data were taken from a L1/L2 dual‐frequency receiver having the capability of tracking only one GPS satellite at a time, on both the L1 and the L2 channels with a data sampling rate of 20 Hz. The receiver phase‐locked loop bandwidth was 16 Hz; thus, the sampling rate was not fast enough to insure that all the spectral components up to the receiver bandwidth were measured. We report on a new analysis of these “old” data illustrating that the rapid rates of change in total electron content (TEC) and high values of the amplitude scintillation index, S4, reported from these data are very relevant today with the advent of modern civilian aircraft routinely flying in the polar latitudes. For instance, we see a very high correlation between individual amplitude fades on the GPS L1 and L2 channels, indicating that users who suffer instantaneous signal loss on one frequency may not be able to use the secondary frequency to recover the GPS signal modulation, since it, too, will suffer an almost identical fade. Also, the occurrence of large, rapid changes in TEC, previously reported from these high‐speed Thule GPS data, has been confirmed and may limit precise positioning in the polar cap latitudes.
Modeling snow accumulation and ablation processes in forested environments
Authors: Andreadis Konstantinos M. , Storck Pascal , Lettenmaier Dennis P.
Published: May 2009

The effects of forest canopies on snow accumulation and ablation processes can be very important for the hydrology of midlatitude and high‐latitude areas. A mass and energy balance model for snow accumulation and ablation processes in forested environments was developed utilizing extensive measurements of snow interception and release in a maritime mountainous site in Oregon. The model was evaluated using 2 years of weighing lysimeter data and was able to reproduce the snow water equivalent (SWE) evolution throughout winters both beneath the canopy and in the nearby clearing, with correlations to observations ranging from 0.81 to 0.99. Additionally, the model was evaluated using measurements from a Boreal Ecosystem‐Atmosphere Study (BOREAS) field site in Canada to test the robustness of the canopy snow interception algorithm in a much different climate. Simulated SWE was relatively close to the observations for the forested sites, with discrepancies evident in some cases. Although the model formulation appeared robust for both types of climates, sensitivity to parameters such as snow roughness length and maximum interception capacity suggested the magnitude of improvements of SWE simulations that might be achieved by calibration.
The HP1α–CAF1–SetDB1‐containing complex provides H3K9me1 for Suv39‐mediated K9me3 in pericentric heterochromatin
Authors: Loyola Alejandra , Tagami Hideaki , Bonaldi Tiziana , Roche Danièle , Quivy Jean Pierre , Imhof Axel , Nakatani Yoshihiro , Dent Sharon Y R , Almouzni Geneviève
Published: June 2009

Trimethylation of lysine 9 in histone H3 (H3K9me3) enrichment is a characteristic of pericentric heterochromatin. The hypothesis of a stepwise mechanism to establish and maintain this mark during DNA replication suggests that newly synthesized histone H3 goes through an intermediate methylation state to become a substrate for the histone methyltransferase Suppressor of variegation 39 (Suv39H1/H2). How this intermediate methylation state is achieved and how it is targeted to the correct place at the right time is not yet known. Here, we show that the histone H3K9 methyltransferase SetDB1 associates with the specific heterochromatin protein 1α (HP1α)–chromatin assembly factor 1 (CAF1) chaperone complex. This complex monomethylates K9 on non‐nucleosomal histone H3. Therefore, the heterochromatic HP1α–CAF1–SetDB1 complex probably provides H3K9me1 for subsequent trimethylation by Suv39H1/H2 in pericentric regions. The connection of CAF1 with DNA replication, HP1α with heterochromatin formation and SetDB1 for H3K9me1 suggests a highly coordinated mechanism to ensure the propagation of H3K9me3 in pericentric heterochromatin during DNA replication.
The role of morphology in stability of Si nanowires
Authors: Migas D. B. , Borisenko V. E.
Published: May 2009

By means of ab initio calculations we have investigated the morphology and stability of nonhydrogenated, free standing, single crystal silicon nanowires oriented along ⟨001⟩, ⟨011⟩, ⟨111⟩, and ⟨112⟩ axes and with diameters ranging from 2 to 5 nm. Different shapes and facet reconstructions have been carefully considered in order to provide a surface without any atoms with two dangling bonds and, eventually, to select the morphology more stable in energy. We have found the ⟨011⟩-oriented silicon nanowires to display the lowest total energy and we also discuss how our results support recent experimental observations.
Electrical resistivity, Debye temperature, and connectivity in heavily doped bulk MgB2 superconductors
Authors: Susner M. A. , Bhatia M. , Sumption M. D. , Collings E. W.
Published: May 2009

The measured transport critical current densities, Jc, of MgB2 superconductors fall short of their intrinsic Jcs on account of the grain boundary blockage, sausaging, and porosity seen in most powder-processed wire samples. Hence, it becomes important to understand and to be able to measure the degree of what can be referred to as “connectivity” in order to be able to assess the highest attainable Jc in a given class of samples. In this paper connectivity is determined with the aid of normal state resistivity in an extension of the model originally proposed by Rowell. The normal-state resistivity temperature dependence is fitted to a standard Bloch–Grüneisen (B-G) equation in the range 50–300 K. Such an approach leads not only to a connectivity parameter but also to other useful data: the actual intragrain residual resistivity (indirectly related to the upper critical field) and a resistively determined Debye temperature, θR. The latter quantity, coupled to the transition temperature, Tc, provides a measure (by way of the McMillan formula) of the electron-phonon coupling constant, usually designated λ. The B-G-based connectivity model was applied to our own experimental data on binary and heavily doped MgB2 samples as well as published resistivity data. To complete the study, low temperature specific heat measurements, performed on binary and doped bulk samples provided calorimetrically determined Debye temperatures, θD, for comparison to the resistively determined values and excellent agreement was found. Calorimetric measurements also probed the homogeneity of the doped samples in terms of the roundness of the electronic specific heat jump near Tc.
Formation characteristics and photoluminescence of Ge nanocrystals in HfO2
Authors: Kim Sung , Won Hwang Sung , Choi Suk-Ho , Elliman R. G. , Kim Young-Min , Kim Youn-Joong
Published: May 2009

Ge nanocrystals (NCs) are shown to form within HfO2 at relatively low annealing temperatures (600–700 °C) and to exhibit characteristic photoluminescence (PL) emission consistent with quantum confinement effects. After annealing at 600 °C, sample implanted with 8.4×1015 Ge cm−2 show two major PL peaks, at 0.94 and 0.88 eV, which are attributed to no-phonon and transverse-optical phonon replica of Ge NCs, respectively. The intensity reaches a maximum for annealing temperatures around 700 °C and decreases at higher temperatures as the NC size continues to increase. The no-phonon emission also undergoes a significant redshift for temperatures above 800 °C. For fluences in the range from 8.4×1015 to 2.5×1016 cm−2, the average NC size increases from ∼13.5±2.6 to ∼20.0±3.7 nm. These NC sizes are much larger than within amorphous SiO2. Implanted Ge is shown to form Ge NCs within the matrix of monoclinic (m)-HfO2 during thermal annealing with the orientation relationship of [101]m-HfO2//[110]Ge NC.
Static gas-liquid interfacial direct current discharge plasmas using ionic liquid cathode
Authors: Kaneko T. , Baba K. , Hatakeyama R.
Published: May 2009

Due to the unique properties of ionic liquids such as their extremely low vapor pressure and high heat capacity, we have succeeded in creating the static and stable gas (plasmas)-liquid (ionic liquids) interfacial field using a direct current discharge under a low gas pressure condition. It is clarified that the ionic liquid works as a nonmetal liquid electrode, and furthermore, a secondary electron emission coefficient of the ionic liquid is larger than that of conventional metal electrodes. The plasma potential structure of the gas-liquid interfacial region, and resultant interactions between the plasma and the ionic liquid are revealed by changing a polarity of the electrode in the ionic liquid. By utilizing the ionic liquid as a cathode electrode, the positive ions in the plasma region are found to be irradiated to the ionic liquid. This ion irradiation causes physical and chemical reactions at the gas-liquid interfacial region without the vaporization of the ionic liquid.
Comparison of the Monte Carlo ion cyclotron heating model with the full-wave linear absorption model
Authors: Choi M. , Chan V. S. , Berry L. A. , Jaeger E. F. , Green D. , Bonoli P. , Wright J. ,   RF SciDAC Team
Published: May 2009

To fully account for the wave-particle interaction physics in ion cyclotron resonant frequency (ICRF) heating experiment, finite orbit effects and non-Maxwellian distribution have to be self-consistently coupled with full-wave solutions. For this purpose, the five-dimensional Monte Carlo code ORBIT-RF [M. Choi et al., Phys. Plasmas 12, 1 (2005)] is being coupled with the two-dimensional full-wave code AORSA [E. F. Jaeger et al., Phys. Plasmas 13, 056101 (2006)] to iteratively evolve the ion distribution in four-dimensional spatial velocity space that is used to update the dielectric tensor in AORSA for evaluating the full-wave fields. In this paper, it is demonstrated that using the full-wave fields from a Maxwellian dielectric tensor in AORSA and confining the resonant ions to their initial orbits in ORBIT-RF, ORBIT-RF largely reproduces the AORSA linear wave absorption profiles for fundamental and higher harmonic ICRF heating. An exception is an observed inward shift in the ORBIT-RF absorption peak for high harmonics near the magnetic axis compared with that of AORSA, which can be attributed to a finite orbit width effect. The success of this verification supports the validity of the Monte Carlo wave-particle interaction model and the readiness of the iterative coupling between ORBIT-RF and AORSA for an improved modeling of ICRF heating experiments.
Finite genus solution of a new (2+1) Burgers equation with a discrete variable
Authors: Yang Xiao , Wang Junmin
Published: May 2009

A new (2+1) Burgers equation with a discrete variable is given as a compatible condition of the Lax pair, which are transformed into two Hamilton flows and a discrete symplectic flow. These flows are integrable in Liouville sense and share the same integrals. By the Abel–Jacobi coordinates, the flows are straightened. Based on the Riemann–Jacobi inverse theorem, a finite genus solution is obtained.
Anomalous yield reduction in direct-drive deuterium/tritium implosions due to H3e addition
Authors: Herrmann H. W. , Langenbrunner J. R. , Mack J. M. , Cooley J. H. , Wilson D. C. , Evans S. C. , Sedillo T. J. , Kyrala G. A. , Caldwell S. E. , Young C. S. , Nobile A. , Wermer J. , Paglieri S. , McEvoy A. M. , Kim Y. , Batha S. H. , Horsfield C. J. , Drew D. , Garbett W. , Rubery M. , Glebov V. Yu. , Roberts S. , Frenje J. A.
Published: May 2009

Glass capsules were imploded in direct drive on the OMEGA laser [Boehly et al., Opt. Commun. 133, 495 (1997)] to look for anomalous degradation in deuterium/tritium (DT) yield and changes in reaction history with H3e addition. Such anomalies have previously been reported for D/H3e plasmas but had not yet been investigated for DT/H3e. Anomalies such as these provide fertile ground for furthering our physics understanding of inertial confinement fusion implosions and capsule performance. Anomalous degradation in the compression component of yield was observed, consistent with the “factor of 2” degradation previously reported by Massachusetts Institute of Technology (MIT) at a 50% H3e atom fraction in D2 using plastic capsules [Rygg, Phys. Plasmas 13, 052702 (2006)]. However, clean calculations (i.e., no fuel-shell mixing) predict the shock component of yield quite well, contrary to the result reported by MIT but consistent with Los Alamos National Laboratory results in D2/H3e [Wilson et al., J. Phys.: Conf. Ser. 112, 022015 (2008)]. X-ray imaging suggests less-than-predicted compression of capsules containing H3e. Leading candidate explanations are poorly understood equation of state for gas mixtures and unanticipated particle pressure variation with increasing H3e addition.