Open Access. Powered by Scholars. Published by Universities.®
- Institution
-
- University of Nebraska - Lincoln (259)
- Department of Primary Industries and Regional Development, Western Australia (52)
- Eastern Illinois University (23)
- University of Arkansas, Fayetteville (14)
- Central Washington University (8)
-
- Brigham Young University (7)
- Old Dominion University (5)
- University of Kentucky (5)
- City University of New York (CUNY) (4)
- West Virginia University (4)
- Arkansas State University (3)
- Chapman University (3)
- Georgia Southern University (3)
- Loma Linda University (3)
- Munster Technological University (2)
- Andrews University (1)
- Ateneo de Manila University (1)
- Bemidji State University (1)
- Cal Poly Humboldt (1)
- Chulalongkorn University (1)
- Claremont Colleges (1)
- Eastern Washington University (1)
- Illinois State University (1)
- Indiana State University (1)
- Liberty University (1)
- Marshall University (1)
- Missouri State University (1)
- Murray State University (1)
- Northern Michigan University (1)
- Otterbein University (1)
- Keyword
-
- Sheep (31)
- Western Australia (19)
- Parasitology (18)
- Ectoparasites (16)
- Helminths (16)
-
- Parasites (16)
- Mongolia (12)
- Bolivia (10)
- Economics (9)
- Mulesing (9)
- Parasite (9)
- Stockholm Paradigm (9)
- Anthelmintics (8)
- Taxonomy (8)
- Trematodes (8)
- Breech strike (7)
- Cattle (7)
- Cestodes (7)
- Nematodes (7)
- Nutrition (7)
- Wool (7)
- Condition score (6)
- Feedlot (6)
- Flystrike (6)
- Lamb (6)
- Liveweight (6)
- Prevalence (6)
- Rodentia (6)
- Rodents (6)
- Acari (5)
- Publication Year
- Publication
-
- Harold W. Manter Laboratory of Parasitology: Faculty Publications (100)
- MANTER: Journal of Parasite Biodiversity (38)
- Harold W. Manter Laboratory of Parasitology: Library Materials (35)
- Masters Theses (23)
- Sheep Updates (22)
-
- Journal of the Department of Agriculture, Western Australia, Series 4 (21)
- Studies from the University of Nebraska Zoological Laboratory (15)
- Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298 (9)
- Scott L. Gardner Publications (9)
- United States Naval Medical Research Unit 3: Publications (8)
- Estudios científicos en el estado de Hidalgo y zonas aledañas (7)
- Graduate Theses and Dissertations (7)
- School of Natural Resources: Faculty Publications (7)
- Theses and Dissertations (7)
- American Society of Parasitologists: Newsletter (5)
- All Master's Theses (4)
- Biological Sciences Faculty Publications (4)
- Graduate Theses, Dissertations, and Problem Reports (ETD) (4)
- Animal Science Undergraduate Honors Theses (3)
- Biology, Chemistry, and Environmental Sciences Faculty Articles and Research (3)
- Dissertations, Theses, and Capstone Projects (3)
- Loma Linda University Electronic Theses, Dissertations & Projects (3)
- School of Biological Sciences: Dissertations, Theses, and Student Research (3)
- Student Theses and Dissertations (3)
- Transactions of the Nebraska Academy of Sciences and Affiliated Societies (3)
- United States Department of Agriculture Wildlife Services: Staff Publications (3)
- Animal production and livestock factsheets (2)
- Biosecurity published reports (2)
- Department of Animal Science: Dissertations, Theses, and Student Research (2)
- Department of Biological Sciences Publications (2)
- Publication Type
Articles 331 - 360 of 421
Full-Text Articles in Parasitology
Hemogregarines In The Red-Eared Slider, Chrysemys Scripta Elegans (Wied) From Arkansas, Chris T. Mcallister, Anthony W. King
Hemogregarines In The Red-Eared Slider, Chrysemys Scripta Elegans (Wied) From Arkansas, Chris T. Mcallister, Anthony W. King
Journal of the Arkansas Academy of Science
No abstract provided.
Arapaho Prairie, Arthur County, Nebraska: Approximate Ap Grid For Gis, Kathleen H. Keeler, A. T. Harrison, L. S. Vescio
Arapaho Prairie, Arthur County, Nebraska: Approximate Ap Grid For Gis, Kathleen H. Keeler, A. T. Harrison, L. S. Vescio
Harold W. Manter Laboratory of Parasitology: Faculty Publications
Grid map of field sites at Arapaho Prairie in Arthur County, Nebraska. Scale 1 5/16" = 1/4 mile. Shows permanently marked vegetation quadrats, blowouts and ravine washouts, roads, and 100' contour intervals. Part of the map was destroyed by mice. What remains of the map as of 2013 is shown.
Dirofilaria Immitis In The Wild Canids Of Illinois, Thomas J. Kick
Dirofilaria Immitis In The Wild Canids Of Illinois, Thomas J. Kick
Masters Theses
The heartworm, Dirofilaria immitis, is widespread in dogs in North America and has been reported in wild canids in many states. This is a report of this parasite in hearts removed from coyote, red fox and gray fox carcasses collected in Illinois. A total of 415 coyotes had a significantly higher infection rate (23.6%) than 225 red foxes (3.6%) and 99 gray foxes (3.0%). Infection rates in red foxes and coyotes were significantly higher in or near the Wabash Border Natural Division along the eastern side of the state, suggesting a relationship between infection rates and this region. The …
Notes On Seasonal Variation And Infectivity Of Haemogamasus Reidi, A Vector Of Hepatozoon Griseisciuri, On Eastern Gray Squirrels, Sciurus Carolinensis, Mohammed Bashiru
Notes On Seasonal Variation And Infectivity Of Haemogamasus Reidi, A Vector Of Hepatozoon Griseisciuri, On Eastern Gray Squirrels, Sciurus Carolinensis, Mohammed Bashiru
Masters Theses
Five hundred and twenty-two squirrels were trapped and retrapped from a population in Montgomery County, Maryland during 1974-1975. One hundred and forty-one squirrels were found to harbor an average of 10.6 mites (Range 175-1). While male squirrels outnumbered females (79 vs 62) females harbored more mites than males (829 vs 666). During the spring the average number of mites per captured squirrel increased to an average of 18.1 per squirrel. The average declined to 6.8, 4.8 and 3.3 per squirrel in summer, fall and winter respectively. Throughout the collection period adult female mites were by far more numerous on hosts …
Flystrike In Sheep : Secondary And Tertiary Flies Striking Sheep In Western Australia, N Monzu
Flystrike In Sheep : Secondary And Tertiary Flies Striking Sheep In Western Australia, N Monzu
Journal of the Department of Agriculture, Western Australia, Series 4
Unlike primary species of blowflies, the secondary and tertiary species of flies cannot initiate a strike, but their activity in the presence of the primary blowflies becomes significant in the death of struck sheep. This is particularily so when the hairy maggot blowfly is involved. Future management of sheep flocks to minimise deaths may require recognition of these secondary and tirtiary flies.
This article presents some basic facts about these flies.
Differentiation Of Fourth And Early Fifth Stages Of Parascaris Equorum (Goeze, 1782) Nematoda: Ascaridoidea, P. A. Pilitt, J. R. Lichtenfels, P. A. Madden
Differentiation Of Fourth And Early Fifth Stages Of Parascaris Equorum (Goeze, 1782) Nematoda: Ascaridoidea, P. A. Pilitt, J. R. Lichtenfels, P. A. Madden
Harold W. Manter Laboratory of Parasitology: Faculty Publications
The morphology of Parascaris equorum of horses was studied; light and scanning electron microscopy were used. Late fourth-stage larvae have narrow, rectangular lips bearing few, large. triangular, irregularly spaced denticles and the lips are not markedly set off from the body. The cutick of the late fourth stage is completely transversely striated, with incomplete longitudinal ridges creating a brickwork pattern; longitudinal alae are present. Total body lengths of fourth-stage larvae range from 10 to 32 mm. A single molting fourth-stage male was found to be 33 mm long. Early fifthstage nematodes have wide, trilobate lips with a deep transverse groove …
Coccidian Parasites Of Wild Turkeys, Meleagris Gallopavo Silvestris, In Illinois, D. Michael Watkins
Coccidian Parasites Of Wild Turkeys, Meleagris Gallopavo Silvestris, In Illinois, D. Michael Watkins
Masters Theses
Fecal samples from 124 wild turkeys (Meleagris gallopavo silvestris), collected in three southern Illinois counties, were examined for coccidia. Three and two tenths percent (4) of the birds sampled were infected with Eimeria of apparently four different species. These species were tentatively designated as: E. meleagridis, E. adendeides, E. meleagrimitis and E. subrotunda.
New Policy Hits Hard At Sheep Lice, F C. Wilkinson
New Policy Hits Hard At Sheep Lice, F C. Wilkinson
Journal of the Department of Agriculture, Western Australia, Series 4
In March 1977 the regulation requiring compulsory routine dipping of all sheep within 30 days of shearing changed, and only infested flocks were required to be dipped. This change has allowed concentrated eradication efforts.
Capillaria Sp. From Cryptotis Parva, Joseph N'Dong
Capillaria Sp. From Cryptotis Parva, Joseph N'Dong
Masters Theses
Twenty-nine Cryptotis parva were trapped at Lincoln Log Cabin State Park in Coles County Illinois between 22 December 1976 and 31 January 1978. Trapped specimens were necropsied and examined for the presence of helminth parasites. Nematode infections were found to be present in eight (27.2%) of the shrews collected with five (17.2%) of the males and three (10.3%) of the females infected. Three adult female nematodes were recovered from the small intestines of the host specimens, described and identified as the genus Capillaria. No male Capillaria were obtained and therefore species identification was impossible. However, the general appearance of …
Epizoic Protozoa Of Planktonic Copepoda And Cladocera From A Small Eutrophic Lake, And Their Possible Use As Indicators Of Organic Water Pollution, Michael Stevens Henebry
Epizoic Protozoa Of Planktonic Copepoda And Cladocera From A Small Eutrophic Lake, And Their Possible Use As Indicators Of Organic Water Pollution, Michael Stevens Henebry
Masters Theses
The epizoic protozoa of planktonic copepoda and cladocera from a eutrophic lake (Ashmore Lake, Coles County, Illinois) were studied over a 13-week period in the summer and fall of 1975. All organisms were collected with a 125 micron mesh plankton net. Epizoans (all peritrichs and suctorians) were hosted by three of four species of copepods and four of the ten species of cladocerans. The percentage of total organisms hosting epizoans varied significantly (0.001 alpha level) by month, but averaged 11.6 percent. This high occurrence of epizoans was thought to be related to the highly-eutrophic conditions existing in the lake. If …
Blood Parasites Of Squirrels From Coles And Lake Counties In Illinois, Nicholas I. Obiri
Blood Parasites Of Squirrels From Coles And Lake Counties In Illinois, Nicholas I. Obiri
Masters Theses
Hepatozoon and microfilariae are described from the blood of fox and gray squirrels captured in Coles and Lake Counties in Illinois during 1976 and 1977. The hepatozoon species is identified as Hepatozoon griseisciuri on the basis of parasite morphology and hosts. A higher rate of infection (35.7% : 11.1%) was observed in gray squirrels than in fox squirrels and more adults were infected than juveniles. No microfilariae were found in gray squirrels but fox squirrels had a 57.1% infection rate with no difference based on age. The observed microfilariae are similar to that described by Davidson from Maryland gray squirrels …
Endoparasites Of Cats In Two Central Utah Communities, Thomas W. Sawyer
Endoparasites Of Cats In Two Central Utah Communities, Thomas W. Sawyer
Theses and Dissertations
A survey of the endoparasites of 100 stray cats in central Utah was conducted. Each cat was euthanized, and the entire alimentary tract, gall bladder, bile duct, heart, respiratory and excretory systems were excised and examined for endoparasites. Fecal samples were examined by a sugar flotation technique. Parasites identified and number of cats infected were: Isospora felis 5; I. rivolta, 4; Dipylidium caninum, 1; Hydatigera taeniaformis, 10; Toxocara mystax, 43; and Physaloptera sp., 2. One ectoparasite, Cheyletiella parasitivorax, was identified in the feces of 4 cats. Dipylidium caninum and T. mystax are known to cause accidental infection in humans and …
Parasites Of California Marine And Estuarine Fish, Milton S. Love, Mike Moser
Parasites Of California Marine And Estuarine Fish, Milton S. Love, Mike Moser
Harold W. Manter Laboratory of Parasitology: Faculty Publications
While working on the parasites of several California marine fish, it was difficult to find out which parasites had been reported from our fish. Pertinent sources were scattered over a number of journals, covering many years. We compiled this list because we felt there was a need for a single source which would give all the parasites infecting California marine fish. As "marine fish" was a somewhat vague term, we decided to use it in a broad sense and included estuarine and anadromous fish in the survey. In addition, we have included records from landlocked populations of anadromous fish, such …
The Arthropod Ectosymbionts Of The Fox Squirrel In Coles County, Illinois, Jeanine L. Stanis
The Arthropod Ectosymbionts Of The Fox Squirrel In Coles County, Illinois, Jeanine L. Stanis
Masters Theses
The body surface areas of 18 squirrels (Sciurus niger) were calculated by regions, and the numbers and densities of the ectoparasite populations present on each region determined. Four species representing four genera of arthropods were recovered. The louse, Neohaematopinus antennatus was the most abundant organism with Orchopeas howardii, Haemagamasus reidi, and Dermacentor variabilis being also present. The average population density of all parasite species combined was highest on the back and decreased on the belly, tail, legs, and the head respectively. Body regions showing greatest average total population densities were different for males and females. The …
Blood Parasites Of Illinois Wild Turkeys, Ulrike G. Guenthner
Blood Parasites Of Illinois Wild Turkeys, Ulrike G. Guenthner
Masters Theses
Blood smears, from 152 wild turkeys (Meleagris gallopavo silvestris) killed during hunting seasons in southern Illinois, were examined for blood parasites. Haemoproteus meleagridis infected 34% of the 83 adult and 19% of the 69 immature turkeys. Of the infected birds, 54% had one or two infected cells per 5000 erythrocytes and 78% had one to five. Infection rates were significantly higher in counties along the Mississippi River than in Pope County, located about 40 miles east of the river. Other parasites specifically searched for but not found were Leucocytozoon, Plasmodium, Trypanosoma and microfilaria.
Parasites Of Channel Catfish In Illinois Hatcheries, Charles Dale Meryman
Parasites Of Channel Catfish In Illinois Hatcheries, Charles Dale Meryman
Masters Theses
Ninety channel catfish (Ictalurus punctatus) were trapped during September 1973 through April 1974 at three hatcheries located at Worden, Centralia, and Kinmundy, Illinois. All were examined for parasites and 87 were parasitized. The trematodes Azygia angusticauda and Neascus sp. were found in the gastrointestinal system and Cleidodiscus floridanus and Dactylogyrus sp. were attached to the gills. Five cestode genera, including Bothriocephalus sp., Corallobothrium giganteum, Eubothrium sp., Haplobothrium sp., and Proteocephalus ambloplitis were present. Rhabdochona sp. was the only nematode found. Protozoans; Costia sp., Myxobolus sp., Scyphidia macropodia and Trichodina discoidea and one kind of glochidium were observed. …
Taxonomy And Zoogeography Of Lemmus Spp. (Rodentia: Arvicolinae), With Notes On Laboratory-Reared Lemmings, Robert L. Rausch, Virginia R. Rausch
Taxonomy And Zoogeography Of Lemmus Spp. (Rodentia: Arvicolinae), With Notes On Laboratory-Reared Lemmings, Robert L. Rausch, Virginia R. Rausch
Harold W. Manter Laboratory of Parasitology: Faculty Publications
Lemmings of the genus Lemmus Link, 1795, have long attracted interest because of the high numerical densities attained at intervals by their populations. In earlier times, in northern Europe, such events seemed so remarkable as to be explained by some as a consequence of the animals' having fallen from the sky (HaGSTROM 1749). During the last 25 years, lemmings have been the object of intensive ecological investigation in Eurasia and North America, although there has been no consensus concerning their taxonomic relationships. In 1959, a colony of brown lemmings from arctic Alaska was established in our laboratory, primarily to provide …
Helminth Parasites Of Illinois Wild Turkeys, James W. Jackson
Helminth Parasites Of Illinois Wild Turkeys, James W. Jackson
Masters Theses
Viscera from 69 wild turkeys (Meleagris gallopavo silvestris) collected from Jackson, Union and Alexander counties, Illinois, were examined for helminth and coccidian parasites. A total of eight species of parasites was found, all in the alimentary tract. The coccidian parasite Eimeria sp. was found in 9.6% of birds examined. The nematodes Heterakis gallinarum, Ascaridia galli and Ascaridia dissimilis were found in 13.2%, 27.9% and 48.5% respectively of all birds examined. Three species of cestodes, Raillietina williamsi, Metroliasthes lucida and Hymenolepis sp., were recovered from 41.1%, 27.9% and 1.4% respectively of birds examined. One species of trematode, …
Ec73-1907 Internal Parasites Of Cattle, D. L. Ferguson
Ec73-1907 Internal Parasites Of Cattle, D. L. Ferguson
University of Nebraska-Lincoln Extension: Historical Materials
Extension Circular 73-1907 is about internal parasites in cows and how they affect cattle production.
Internal parasites continue to be one of the major problems confronting cattle producers. In 1965, the United States Department of Agriculture estimated that internal parasites in cattle caused an average annual loss of $161,678,000. The internal parasites responsible for the annual loss are listed below.
Anaplasmosis. .$ 36,001,000
Coccidiosis . . . .14,569,000
Worm Parasites .100,046,000
Liver Flukes . . . 3,022,000
Trichomoniasis .. 8,040,000
In cattle the effects of internal parasites will be well camouflaged. However, additional feed will be required to reach market …
Gastro-Intestinal And Abdominal Helminths Of White-Tailed Deer (Odocoileus Virginianus) From Carroll And Jo Daviess Counties In Northern Illinois, Jeffrey Joseph Hodge
Gastro-Intestinal And Abdominal Helminths Of White-Tailed Deer (Odocoileus Virginianus) From Carroll And Jo Daviess Counties In Northern Illinois, Jeffrey Joseph Hodge
Masters Theses
Forty-four white-tailed deer shot by hunters in November and December, 1971, in Carroll and Jo Daviess counties in northwestern Illinois were necropsied for gastro-intestinal and abdominal helminths. Five species of gastro-intestinal nematodes were found: Gongylonema pulchrum, Ostertagia odocoilei, Haemonchus contortus, Trichuris ovis and Nematodirus sp. Setaria yehi, a filiariad nematode, was found in the abdominal cavity. Moniezia benedeni was the only cestode found. No trematodes were recovered. Differences in numbers and kinds of parasites found in northern Illinois and southern Illinois are discussed. Prevalence increased with host age for certain species of parasites and decreased or …
Parasites Of Some Penaeid Shrimps With Emphasis On Reared Hosts, Robin M. Overstreet
Parasites Of Some Penaeid Shrimps With Emphasis On Reared Hosts, Robin M. Overstreet
Harold W. Manter Laboratory of Parasitology: Faculty Publications
Information is presented about parasites and commensals of penaeid shrimps, allowing those who rear shrimps and those who are interested in associated organisms of shrimp to have a better knowledge of the organisms that are or may be associated with brown, white, and pink shrimps. It covers common and rare organisms and diseases, primarily in the northern Gulf of Mexico, listing several previously unreported species including an undescribed gregarine, a larval nematode (Spirocarnallanus pereirai), a commensal nematode (Leptolaimus sp.), a leech (Myzobdella lugubris), a blue-green alga (Schizothrix calcicola), a hydroid (Obelia bicuspidata …
Parasites From Gizzard Shad, Dorosoma Cepedianum, In Lake Charleston, Illinois, Francis M. Yabai Kaikumba
Parasites From Gizzard Shad, Dorosoma Cepedianum, In Lake Charleston, Illinois, Francis M. Yabai Kaikumba
Masters Theses
Eighty gizzard shad (Dorosoma cepedianum) from Lake Charleston, Charleston, Illinois were examined for parasites. Eight fish were parasitized. Three fish contained the acanthocephalan Tanaorhamphus longirostris, three fish harbored cestodes of the genus Glaridacris and two fish had the nematode Camallanus oxycephalus. The latter is here reported for the first time from gizzard shad. Twenty fish were infected with the fungus Saprolegnia sp. The numbers of helminth parasites harbored by shad are less than reported for other forage fish. However, the incident of parasitism reported in this study is greater than that reported by previous workers.
The Reproductive Biology Of The Leech Helobdella Stagnalis (Linnaeus) In Utah Lake, David L. Tillman
The Reproductive Biology Of The Leech Helobdella Stagnalis (Linnaeus) In Utah Lake, David L. Tillman
Theses and Dissertations
The reproductive biology of the brooding leech Helobdella stagnalis (Linnaeus) in Utah Lake was studied for an 18 month period from June 1970 to December 1971. In determining the annual reproductive cycle, the number of adult leeches carrying eggs or young were counted at weekly intervals during the reproductive season and monthly during the rest of the year. Gonadal staging data from histological sections were correlated with the field collection data. It was found that two broods of young were produced by the adult animals during the reproductive season. Continuous water temperatures were recorded at the study site throughout the …
Gastro-Intestinal And Abdominal Helminths Of White-Tailed Deer (Odocoileus Virginianus) In Southern Illinois, Thomas W. Cook
Gastro-Intestinal And Abdominal Helminths Of White-Tailed Deer (Odocoileus Virginianus) In Southern Illinois, Thomas W. Cook
Masters Theses
In November and December 1971, forty deer from five southern Illinois counties were examined by necropsy for gastro-intestinal and abdominal helminths. Eight species of gastro-intestinal nematodes were found: Gongylonema pulchrum, Spiculopteroides odocoilei, Ostertagia mossi, Haemonchus contortus, Cooperia sp., Capillaria sp., Trichuris ovis and Oesophagostomum venulosum. Setaria yehi, a filiariad nematode, was found in the abdominal cavity. Moniezia benedeni was the only cestode found. No trematodes were recovered.
Gastro-Intestinal Helminths Of Illinois Bobwhites, Michael Eugene Gordon
Gastro-Intestinal Helminths Of Illinois Bobwhites, Michael Eugene Gordon
Masters Theses
The viscera of 103 bobwhite quail (Colinus virginianus), from east central Illinois counties, were collected during November and December of 1971 and examined for helminth parasites. Two nematodes were identified: Dispharynx nasuta (9.7%) and Ascaridia sp. (7.8%). The rate of infection varied significantly between counties but there was no difference in parasitism of males and females.
Post-Mortem Examination Of Cattle And Sheep For Parasitic Helminths, Phil Duke Wright
Post-Mortem Examination Of Cattle And Sheep For Parasitic Helminths, Phil Duke Wright
Theses and Dissertations
A survey of helminth parasites of sheep and cattle was conducted to determine the incidence and distribution of these parasites that could be detected by post-mortem examination. Animals were obtained from local abattoirs within the valley, and the viscera were examined for the presence of helminth parasites. Parasites identifies from sheep in order of highest incidence were: Haemonchus contorus, Ostertagia cicumcinta, Chabertia ovina, Nematodirus spathiger, Trichostongylus colubriformis, Thysanosoma actinioides, Trichuris ovis, N. filicollis, Echinococcus granulosus, Strongyloides papillosus, O. ostertagi, Cooperia oncophora, Cysticercus tenuicollis, Fasciola hepatica, Oesophagostomum venulosum, Moniezia expansa, and M. benedieni. Those recovered from cattle in order of highest …
Flystrike Control Programmes, H E. Fels
Flystrike Control Programmes, H E. Fels
Journal of the Department of Agriculture, Western Australia, Series 4
THE various flystrike control methods all avoid susceptible patches of skin on the sheep.
To avoid work—
• choose methods that give the most control for the least effort, and
• combine these methods into a system that works well.
How To Control Flystrike In Sheep, H E. Fels
How To Control Flystrike In Sheep, H E. Fels
Journal of the Department of Agriculture, Western Australia, Series 4
FLYSTRIKE affects incomes and efficiency because a large part of the work done on sheep farms is to prevent or treat it, and because it kills sheep and reduces the amount and quality of production.
Protozoan And Helminth Parasites Of White-Tailed Deer (Odocoileus Virginianus) In Southern Illinois, Sarah M. Mugwanya
Protozoan And Helminth Parasites Of White-Tailed Deer (Odocoileus Virginianus) In Southern Illinois, Sarah M. Mugwanya
Masters Theses
No abstract provided.
Effect Of Splenectomy On Relapse Of Hemal Parasites In Pigeons, Phillip James Sprino
Effect Of Splenectomy On Relapse Of Hemal Parasites In Pigeons, Phillip James Sprino
Masters Theses
No abstract provided.