238,318 research outputs found
Cowpox virus infection in natural field vole Microtus agrestispopulations: significant negative impacts on survival
No full text1. Cowpox virus is an endemic virus circulating in populations of wild rodents. It has been implicated as a potential cause of population cycles in field voles Microtus agrestis L., in Britain, owing to a delayed density-dependent pattern in prevalence, but its impact on field vole demographic parameters is unknown. This study tests the hypothesis that wild field voles infected with cowpox virus have a lower probability of survival than uninfected individuals. 2. The effect of cowpox virus infection on the probability of an individual surviving to the next month was investigated using longitudinal data collected over 2 years from four grassland sites in Kielder Forest, UK. This effect was also investigated at the population level, by examining whether infection prevalence explained temporal variation in survival rates, once other factors influencing survival had been controlled for. 3. Individuals with a probability of infection, P(I), of 1 at a time when base survival rate was at median levels had a 22.4% lower estimated probability of survival than uninfected individuals, whereas those with a P(I) of 0.5 had a 10.4% lower survival. 4. At the population level, survival rates also decreased with increasing cowpox prevalence, with lower survival rates in months of higher cowpox prevalence. 5. Simple matrix projection models with 28 day time steps and two stages, with 71% of voles experiencing cowpox infection in their second month of life (the average observed seroprevalence at the end of the breeding season) predict a reduction in 28-day population growth rate during the breeding season from λ = 1.62 to 1.53 for populations with no cowpox infection compared with infected populations. 6. This negative correlation between cowpox virus infection and field vole survival, with its potentially significant effect on population growth rate, is the first for an endemic pathogen in a cyclic population of wild rodents
Delta Marsh Field Station Archive Annual Report, Volume 4, 1969
No full textThe University Field Station had another successful
season and fifteen research projects were undertaken during the summer.
They included:--popu1ation and productivity studies in algae and
emergent marsh species; nitrification processes in marsh soils; the
relationship between evapotranspiration in Phragmites and water table
fluctuations; ecological studies on benthic fauna; factors determining
mollusc distribution; population dynamics of Brook Sticklebacks;
comparative ecology of two species of Shiner; internal helminths of
two amphibian species; reproductive biology of Forster's Tern; territory
in the Yellow Warbler, seasonal energy balance in the muskrat; geomorphic,
sedimentological and stratigraphic investigations of the area between
Portage la Prairie and Lake Manitoba and groundwater studies in the
Delta area.
We had the pleasure of visits from a number of distinguished
scientists from various parts of the world. The Department of Anthropology
held a field course for one month and groups from Botany and Zoology stayed
at the Station for shorter periods of time.
The following staff, students and technicians spent all
or part of the summer at the Field Station:
FACULTY
J. M. Walker
G. G. C. Robinson
J. Wright
C. T. Shay
R. M. Green
GRADUATE STUDENTS
T.O. Acere (Zoology)
H. Bauer (Psychology)
D. Bernard (Zoology)
D. Brown (Botany)
L. H1ynka (Zoology)
M. Fenton (Earth Science)
D. Lutchman (Earth Sdence)
M. McNicholl (Zoology)
F. Phillips (Botany)
SUMMER ASSISTANTS
W. Dentry
L. Hendzel
T. Hochbaum
J. Leberdensky
P. Lemon
K. Machniak
R. Moyshenko
T. Sulymko
G. Vascatto
J. Yarysz
C.K. Yeung
The first project started in early April, and from then
until mid-September the accommodation was used for 265 resident-weeks
with 4,269 meals being served! There are two projects continuing
throughout the winter. Seminars
A weekly programme of seminars and films was held in June
July and August , and we were privileged to hear lectures from
Dr . L. Rudescu (Roumania), Dr . R. Nero (Manitoba Museum of Man and Nature),
Dr . R. Miller (Yale University) , Mr . L. Gray (Water Control and
Conservation , Department of Mines and Natural Resources), Dr . J. M. Walker
(Botany, University of Manitoba), Dr . E. S. Burch (Anthropology,
University of Manitoba), Dr. G. G. C. Robinson (Botany, University of
Manitoba), Dr . D. Schindler (Fisheries Research Board, Winnipeg), and
Dr . G. Brunskill (Fisheries Research Board, Winnipeg). We welcomed
the participation of members of the Delta Waterfowl Research Station at
these seminars and appreciated their invitation to attend the two-day
Seminar on "Spacing Mechanisms in Waterfowl" and their July and August
seminar series.
At the 3rd November Seminar fifteen research summaries
were presented, including reports from Mr . F. Austin and Mr. P. Ould,
graduate students in the Department of Zoology who carried out their work
at the Delta Waterfowl Research Station. The seminar attracted about
80 people, promoted discussion and is now well established as an important
part of the Field Station programme . Brief summaries of most of these
projects form the major part of this Annual Report.
Courses
Anthropology 76.662
A small Archaeological Field School led by Prof. C. T. Shay
of the Department of Anthropology was held during the month of July.
The class surveyed for archaeological sites in the area and spent two
weeks excavating a small campsite on the Bell Estate. The campsite,
located on a small beachridge, yielded stone artifacts and pottery dating
between 1300-1600 A. D. We would like to extend to Mr. P. Ward our
appreciation for permission to excavate this site and for helpful
assistance throughout the course.
Comparative Chordate Zoology 22.220 and Plant Kingdom 1.220
Dr . G. Ross and Dr. B. Young respectively spent useful
days at the Field Station with their students.
Introductory Ecology (Botany 1.336 and Zoology 22 . 334)
Three sections each of 3 1/2 days duration were organized
by Drs. J. Gee, J. M. Stewart. J. M. Walker and J. F. Wright, assisted
by Mr. D. Bernard. Two sections were held in Registration Week and one
the following weekend. During the course, the students were introduced to
a variety of habitats, sampling techniques and methods of assessing
environmental parameters, which give an insight into the structure and
functioning of ecosystems .
2 Plant Ecology 1.452
Drs. J. M. Stewart and J. M. Walker organized a weekend
course in Plant Ecology with emphasis upon ordination and sampling
techniques as an aid to plant community description.
Advanced Taxonomy 1.442
Dr. R. Longton conducted a weekend course during which
intensive collecting of critical groups from a range of habitats
was undertaken. The collections were for analysis later in the term.
Marsh Ecology 1.721
The Marsh Ecology course spent a weekend at the Station
with Drs. J. M. Stewart and J. M. Walker, and examined the plant
communities =rom the lakeshore to the forested ridge and from the
wet meadow to the marsh. Materials were collected for plant and soil
analysis, calorific determinations, etc.
Visitors
We had the pleasure of visits from members of a number
of other Universities and institutions: Dr. T. Pritchard (Nature
Conservancy, U.K.), Dr. D. Bellamy (Durham), Dr. L. Rudescu (Bucharest,
Rumania), Dr. K. Patalas (Freshwater Institute), Dr. Bilden (Macdonald
College), Dr. D. Pimlott (Toronto), Dr. G. Ross (Southern), the members
of the Board of Trustees of the North American Wildlife Foundation,
Dr. B. Kendrick (Waterloo), Miss V. Humphreys (National Museum, Ottawa)
Miss M. Dwyer (National Parks, Ottawa), Mr. E. Carp (International Wildlife
Research Bureau), Dr. A. Johnson (Hendrix College), the members of the
11th Delta Waterfowl Research Station Seminar, Dr. G. MacLachlan (McGill),
Dr. J. Burnett (Glasgow), Dr. H. Dale (Guelph).
Special Events
There were three events worthy of special mention. On
August 14th, Dr. H. H. Saunderson officially opened the new laboratories
at the Station, when we were happy to be joined by friends from the
University, Provincial Government and others. A tour of the facilities
and displays by graduate students helped to make the day a memorable
one.
The Biology Division Picnic in July was the occasion for
a gathering of more than eighty for a beach celebration which became
the merrier when driven indoors by rain.
Perhaps the marathon social event was a barbeque supper
for the 128 participants at the International Coregonid Conference on
August 27th, accompanied by suitable musical revelry.
3 Buildings
During the winter and spring two cottages were built
east of Mallard Lodge and Murrays Cottage was renovated . The transformation
of the latter was completed with the assistance of graduate students
armed with paint brushes and permitted the building to be used for the
Archaeology Field Course. The Bell House was converted into a laboratory
by Dr. Robinson and Dennis Brown. However, despite this increase in
facilities, the basement of the lodge was in constant use as a laboratory.
A site plan and survey was prepared during September to enable future
expansion to take place on an orderly basis.
I would like to express appreciation for the efforts the
Provincial Government made to acquire for the Field Station two housing
units from the Macdonald Airfield. These will be brought to Delta during
the winter and will provide the laboratory and living accommodation which
is essential if an expanding programme of research and teaching is to
be carried out at the Field Station.
General
We are grateful for the opportunities afforded to us to use
the Bell Estate for various projects and for the friendly co-operation
extended to us by the members of the Delta Waterfowl Research Station.
Thanks are also due to the Portage Country Club for allowing us to use
their property for study' purposes.
To all departments of the Provincial Government upon whose
jurisdiction we impinge, warm thanks are extended for their many
kindnesses.
I would like to thank all the staff for their help during
the season and look forward to an even more successful year in 1970
L-invariants for cohomological representations of PGL(2) over arbitrary number fields
No full textGehrmann L, Pati MR. L-invariants for cohomological representations of PGL(2) over arbitrary number fields. Forum of Mathematics, Sigma. 2024;12: e71.**Abstract**
Let
be a cuspidal, cohomological automorphic representation of an inner form
G
of
over a number field
F
of arbitrary signature. Further, let
be a prime of
F
such that
G
is split at
and the local component
of
at
is the Steinberg representation. Assuming that the representation is noncritical at
, we construct automorphic
-invariants for the representation
. If the number field
F
is totally real, we show that these automorphic
-invariants agree with the Fontaine–Mazur
-invariant of the associated
p
-adic Galois representation. This generalizes a recent result of Spieß respectively Rosso and the first named author from the case of parallel weight
to arbitrary cohomological weights.
</p
The Entrepreneurship SIG at the European Academy of Management: Setting the Base for Tomorrow's Challenges
No full textThis third volume of the book series The Entrepreneurship SIG at the European Academy of Management brings together contributions on aspects characterizing the field of entrepreneurship, such as entrepreneurial behavior and mindsets and business models, but addressed in light of some of the dynamics of change that characterize the current context, such as digitalization. Moreover, the book also discusses emerging issues in academic debate, including in the wake of the recent COVID 19 pandemic, such as resilience, and relevant business contexts, such as that of family businesses. The book valorizes different contexts and key strengths of the European perspective
Modulation of the wall-heat transfer in turbulent thermomagnetic convection by magnetic field gradients
No full textWe present combined experimental and numerical studies of the heat transfer of paramagnetic or diamagnetic fluid inside a differentially heated cubical enclosure subjected to the magnetic field gradients of different strength and orientation. In contrast to the previously reported studies in literature, which observed solely laminar flow regimes, here we focused on the fully developed turbulent flow regimes. That was possible by using a combination of the state-of-art superconducting magnets (with a strength up to 10 T and magnetic field gradients up to 900 T/m) and by selecting various paramagnetic or diamagnetic working fluids (in a range of Pr). Detailed comparison between experiments (integral wall-heat transfer, temperature time-series at different locations within the enclosure) and direct numerical simulations (DNS) are performed and generally very good agreements are obtained in predicting the integral heat transfer. In addition, analysis of the long-term averaged first- and second-moments of velocity and thermal fields is performed. Finally, budgets of the turbulent kinetic energy and of the temperature variance are analyzed and the mean mechanism of the thermal plume reorganization in terms of the proper-orthogonal decomposition (POD) modes is presented
Natural control of Liriomyza trifolii (Diptera: Agromyzidae) on fresh market green peppers
No full textTypescript (photocopy).The spatial distribution of Liriomyza trifolii (Burgess) and its associated hymenopterous parasite complex was determined in field grown bell peppers at Weslaco, TX. L. trifolii larvae were most numerous during the first weeks of plant growth on cotyledons and thereafter on mature leaves. After plants reached 75 mm in height (>12 leaves per plant), larvae could be most reliably sampled on mature leaves from the middle 1/3 of the plant. Dispersion indices indicated that L. trifolii larvae were slightly aggregated in the field. Correspondingly, parasitized L. trifolii larvae were randomly distributed within individual plants and amongst plants in the field indicating a random parasite oviposition behavior. L. trifolii larval densities within the field increased slowly during a growing season with some changes in stability of age distribution through time also noted. The loss of leaf area from mining accumulated over time appeared to be the major cause of damage by L. trifolii. Laboratory studies at 24��C showed that mean developmental time from oviposition to adulthood was 20 days. High levels of unexplained mortality occurred in egg and pupal stages. The efficacy of L. trifolii parasites in field grown bell peppers was determined using mechanical exclusion techniques and life table analyses. Parasitism of L. trifolii larvae by seven parasite species was a significant factor in limiting density increases. However, unexplained L. trifolii larval and pupal mortality was equally important. In the absence of parasitism, L. trifolii parasite induced mortality was partially replaced by unexplained larval and pupal mortality. The lack of L. trifolii adult and egg mortality data left questions as to the exact role of all mortality agents. No one mortality factor regulated L. trifolii density in the systems studied
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
[Memorandum from Major L. M. Fellbaum to T. N. Carswell - December 21, 1944]
No full textA memorandum from L. M. Fellbaum, Major, Q. M. C. Chief, Field Division to Mr. T. N. Carswell, dated December 21, 1944. Fellbaum advises Carswell of the enclosed, amended Itinerary. He requests that Carswell assist in training a new clerk and advises of additional requirements when working with these boards. Typewritten on paper bearing U S Eagle watermark. Enclosure includes: (Amended) ITINERARY for Thomas N. Carswell for Special work dated 1944-45, 12-5 to 1-13. Approved and signed by L. M. Fellbaum, Major, Q. M. C. Chief, Field Division
Young massive stars in the ISOGAL survey. I. VLA observations of the ISOGAL l=+45 field
No full textWe present VLA radio continuum observations at 3.6 and 6 cm of a ~ 0.65 sq. deg. field in the galactic plane at l=+45(deg) . These observations are meant to be used in a comparison with ISO observations at 7 and 15 mu m of the same region. In this paper we compare the radio results with other radio surveys and with the IRAS-PSC. At 3.6 and/or 6 cm we detect a total of 34 discrete sources, 13 of which are found in five separate extended complexes. These are all multiple or single extended thermal ultra-compact HII (UCHII) regions. While for each of these complexes an IRAS counterpart could be reliably found, no IRAS counterpart could be reliably identified for any of the remaining 21 sources. Of these 21 compact sources, six are candidate UCHII regions, and the other 15 are most probably background extragalactic non-thermal sources. The five IRAS sources associated with the radio continuum complexes all satisfy the \cite[Wood & Churchwell (1989a]{WC89}; WC89) color criteria for UCHII. None of the other 38 IRAS point sources present in our surveyed field show the same colors. This fraction of WC89 type to total IRAS sources is consistent with what is found over the entire galactic plane. The fact that, when observed with a compact VLA configuration, the IRAS sources with ``UCHII colors'' are found to be associated with arcminute-scale extended sources, rather than with compact or unresolved radio sources, may have important implications on the estimated lifetime of UCHII regions
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