719 research outputs found
Improving the Use of Migration Counts for Wildlife Population Monitoring
Counts of migrating animals are used to monitor populations, particularly for species that are not well sampled by breeding and wintering surveys. The use of migration counts for population monitoring relies on the assumptions that new individuals are detected each day, and that probability of detecting those individuals remains constant over time. The impact of violating these assumptions on our ability to estimate reliable population trends is not well understood. Further, on a broad spatial scale, our ability to combine data across sites to estimate regional or national trends has been limited by the possibility that trends vary regionally in an unknown way. Using simulated migration count data with known trend, I tested whether sampling effort (daily vs. non-daily sampling) and a temporal change in stopover duration (and thus detection probability) influenced our ability to estimate the known trend. I also tested whether analyzing data as hourly, daily or annual counts, or accounting for random error using analytical techniques, could improve accuracy and precision of estimated trends by reducing or better modeling variation in counts, respectively. Further, using model selection analytical techniques, I tested whether we could detect when trends vary regionally using current or increased number of sampling sites in a region. My findings show that trends can be improved for species with highly variable daily counts by sampling less frequently than daily or by aggregating hourly counts to annual totals. Commonly and rarely detected species were better analyzed as daily counts, collected daily throughout the migration. A linear increase in stopover duration over time biased trends and lead to a high probability of detecting an incorrect trend, which is only improved by both reducing sampling effort and including a covariate for stopover duration in regression analyses. Regional variation in trends can be detected, and increasing the length of the time series was more efficient for improving accuracy and precision of regional trends than increasing the number of sites sampled. Continued advancement of our knowledge of breeding origins and stopover duration of migrants are priorities for the further refinement of trends estimated using migration counts
Murine leukaemia virus expression in the AKR following thymectomy.
Thymectomy effectively prevents the development of spontaneous lymphoma in the AKR but how this effect is achieved remains to be determined. One possible mechanism, namely suppression of genomic expression of the oncogenic murine leukaemia virus now seems unlikely since levels of the group specific MuLV antigen were in comparision with their sham operated controls unaltered in both neonatally and adult thymectomized AKR
The Ties That Bind: Materiality, Identity, and the Life Course in the âThingsâ Families Keep
Using an interdisciplinary research methodology across three archaeological and historical case studies, this article explores âfamily archives.â Four themes illustrate how objects held in family archives, curation practices, and intergenerational narratives reinforce a familyâs sense of itself: peopleâobject interactions, gender, socialization and identity formation, and the âlife course.â These themes provide a framework for professional archivists to assist communities and individuals working with their own family archives. We argue that the family archive, broadly defined, encourages a more egalitarian approach to history. We suggest a multiperiod analysis draws attention to historical forms of knowledge and meaning-making practices over time
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Mothers behaving badly: chaotic hedonism and the crisis of neoliberal social reproduction
This article focuses on the significance of the plethora of representations of mothers âbehaving badlyâ in contemporary anglophone media texts, including the films Bad Moms, Fun Mom Dinner and Bad Momâs Christmas, the book and online cartoons Hurrah for Gin and the recent TV comedy dramas Motherland, The Let Down and Catastrophe. All these media texts include representations of, first, mothers in the midst of highly chaotic everyday spaces where any smooth routine of domesticity is conspicuous by its absence; and second, mothers behaving hedonistically, usually through drinking and partying, behaviour that is more conventionally associated with men or women without children. After identifying the social type of the mother behaving badly (MBB), the article locates and analyses it in relation to several different social and cultural contexts. These contexts are: a neoliberal crisis in social reproduction marked by inequality and overwork; the continual if contested role of women as âfoundation parentsâ; and the negotiation of longer-term discourses of female hedonism. The title gestures towards a popular British sitcom of the 1990s, Men Behaving Badly, which popularized the idea of the ânew ladâ; and this article suggests that the new ladâs counterpart, the ladette, is mutating into the mother behaving badly, or the âlad momâ. Asking what work this figure does now, in a later neoliberal context, it argues that the mother behaving badly is simultaneously indicative of a widening and liberating range of maternal subject positions and symptomatic of a profound contemporary crisis in social reproduction. By focusing on the classed and racialised dynamics of the MBB â by examining who exactly is permitted to be hedonistic, and how â and by considering the MBBâs limited and partial imagining of progressive social change, the article concludes by emphasizing the urgency of creating more connections between such discourses and âparents behaving politicallyâ
Reproductive Biology of the Cape Honeybee: A Critique of Beekman et al: A critique of "Asexually Produced Cape Honeybee Queens (Apis mellifera capensis) Reproduce Sexually,â authors: Madeleine Beekman, Michael H. Allsopp, Julianne Lim, Frances Goudie, and Benjamin P. Oldroyd. Journal of Heredity. 2011:102(5):562-566
Laying workers of the Cape honeybee parthenogenetically produce female offspring, whereas queens typically produce males. Beekman et al. confirm this observation, which has repeatedly been reported over the last 100 years including the notion that natural selection should favor asexual reproduction in Apis mellifera capensis. They attempt to support their arguments with an exceptionally surprising finding that A. m. capensis queens can parthenogenetically produce diploid homozygous queen offspring (homozygous diploid individuals develop into diploid males in the honeybee). Beekman et al. suggest that these homozygous queens are not viable because they did not find any homozygous individuals beyond the third larval instar. Even if this were true, such a lethal trait should be quickly eliminated by natural selection. The identification of sex (both with molecular and morphological markers) is possible but notoriously difficult in honeybees at the early larval stages. Ploidy is however a reliable indicator, and we therefore suggest that these "homozygousâ larvae found in queen cells are actually drones reared from unfertilized eggs, a phenomenon well known by honeybee queen breeder
Imaging and Dynamics of Light Atoms and Molecules on Graphene
Observing the individual building blocks of matter is one of the primary
goals of microscopy. The invention of the scanning tunneling microscope [1]
revolutionized experimental surface science in that atomic-scale features on a
solid-state surface could finally be readily imaged. However, scanning
tunneling microscopy has limited applicability due to restrictions, for
example, in sample conductivity, cleanliness, and data aquisition rate. An
older microscopy technique, that of transmission electron microscopy (TEM) [2,
3] has benefited tremendously in recent years from subtle instrumentation
advances, and individual heavy (high atomic number) atoms can now be detected
by TEM [4 - 7] even when embedded within a semiconductor material [8, 9].
However, detecting an individual low atomic number atom, for example carbon or
even hydrogen, is still extremely challenging, if not impossible, via
conventional TEM due to the very low contrast of light elements [2, 3, 10 -
12]. Here we demonstrate a means to observe, by conventional transmision
electron microscopy, even the smallest atoms and molecules: On a clean
single-layer graphene membrane, adsorbates such as atomic hydrogen and carbon
can be seen as if they were suspended in free space. We directly image such
individual adatoms, along with carbon chains and vacancies, and investigate
their dynamics in real time. These techniques open a way to reveal dynamics of
more complex chemical reactions or identify the atomic-scale structure of
unknown adsorbates. In addition, the study of atomic scale defects in graphene
may provide insights for nanoelectronic applications of this interesting
material.Comment: 9 pages manuscript and figures, 9 pages supplementary informatio
The significance of 'the visit' in an English category-B prison: Views from prisoners, prisoners' families and prison staff
A number of claims have been made regarding the importance of prisoners staying in touch with their family through prison visits, firstly from a humanitarian perspective of enabling family members to see each other, but also regarding the impact of maintaining family ties for successful rehabilitation, reintegration into society and reduced re-offending. This growing evidence base has resulted in increased support by the Prison Service for encouraging the family unit to remain intact during a prisonerâs incarceration. Despite its importance however, there has been a distinct lack of research examining the dynamics of families visiting relatives in prison. This paper explores perceptions of the same event â the visit â from the familiesâ, prisonersâ and prison staffs' viewpoints in a category-B local prison in England. Qualitative data was collected with 30 prisonersâ families, 16 prisoners and 14 prison staff, as part of a broader evaluation of the visitorsâ centre. The findings suggest that the three parties frame their perspective of visiting very differently. Prisonersâ families often see visits as an emotional minefield fraught with practical difficulties. Prisoners can view the visit as the highlight of their time in prison and often have many complaints about how visits are handled. Finally, prison staff see visits as potential security breaches and a major organisational operation. The paper addresses the current gap in our understanding of the prison visit and has implications for the Prison Service and wider social policy
Pion-Muon Asymmetry Revisited
Long ago an unexpected and unexplainable phenomena was observed. The
distribution of muons from positive pion decay at rest was anisotropic with an
excess in the backward direction relative to the direction of the proton beam
from which the pions were created. Although this effect was observed by several
different groups with pions produced by different means, the result was not
accepted by the physics community, because it is in direct conflict with a
large set of other experiments indicating that the pion is a pseudoscalar
particle. It is possible to satisfy both sets of experiments if helicity-zero
vector particles exist and the pion is such a particle. Helicity-zero vector
particles have direction but no net spin. For the neutral pion to be a vector
particle requires an additional modification to conventional theory as
discussed herein. An experiment is proposed which can prove that the asymmetry
in the distribution of muons from pion decay is a genuine physical effect
because the asymmetry can be modified in a controllable manner. A positive
result will also prove that the pion is NOT a pseudoscalar particle.Comment: 9 pages, 3 figure
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