310 research outputs found
Orbit design for future SpaceChip swarm missions in a planetary atmosphere
No full textThe effect of solar radiation pressure and atmospheric drag on the orbital dynamics of satellites-on-a-chip (SpaceChips) is exploited to design equatorial long-lived orbits about the oblate Earth. The orbit energy gain due to asymmetric solar radiation pressure, considering the Earth's shadow, is used to balance the energy loss due to atmospheric drag. Future missions for a swarm of SpaceChips are proposed, where a number of small devices are released from a conventional spacecraft to perform spatially distributed measurements of the conditions in the ionosphere and exosphere. It is shown that the orbit lifetime can be extended and indeed selected through solar radiation pressure and the end-of-life re-entry of the swarm can be ensured, by exploiting atmospheric drag
Study of squirrelpox virus in red and grey squirrels and an investigation of possible routes of transmission
No full textThe red squirrel (Sciurus vulgaris) is native to Eurasia, but in the UK its survival is
being threatened by the non-native grey squirrel (Sciurus carolinensis). Since its
introduction to the UK from the USA the grey squirrel has increased its range at the
expense of the red squirrel. Although competition for resources clearly plays a role in
this replacement, an infectious viral disease, caused by squirrelpox virus (SQPV) and
hosted apparently asymptomatically by the grey squirrels, has now been recognised
as a major contributing factor.
Little is known about the pathogenesis of infection in grey squirrels in comparison to
red squirrels, but understanding this is essential to determining how the virus spreads
within and between the red and grey squirrels. The aims of this thesis were to
investigate the course of SQPV infection in red and grey squirrels and possible routes
of virus transmission. Specifically, for the first time, a novel Real Time PCR (qPCR)
assay and immunohistochemistry were used to investigate the presence of SQPV in
various tissues from naturally infected red squirrels and experimentally infected grey
squirrels.
In diseased red squirrels SQPV DNA was found in several tissues with the highest
amounts being found in skin samples. This reflects the multiple lesions that were
easily visible on the red squirrel carcasses. There was no indication of systemic
disease although the viral DNA was detected, at lower levels, in other internal
organs. Grey squirrels were experimentally infected with SQPV isolated from
naturally-infected red squirrels with fatal clinical disease. In contrast to SQPV-infected
red squirrels no clinical lesions, other than mild scab formation at the site of
inoculation, were found in the grey squirrels post-infection. No gross pathological
changes indicative of systemic infection were observed and these findings were
reflected in the qPCR and histopathology results. Viral DNA was only detected by
qPCR in samples from the site of inoculation (scarified skin) and at lower
concentrations in other skin tissues such as digital and eyelid skin. In addition,
histopathology and immunohistochemistry examination revealed evidence of
infection characterized by ballooning degeneration of keratinocytes, and acanthosis
and spongiosis of the epidermis. These skin lesions were self limiting and minor
compared to the infected red squirrel skin samples.
The molecular variation in the virus isolated over time from different parts of the UK
was also investigated. Seven SQPV isolates (4 from Scotland and 3 from England)
were tested and results indicated that there are no significant changes in the amino
acid sequence of any of the three genes examined apart from one amino acid change
(one base change) in one gene. All Scottish isolates examined showed this change in
comparison to English isolates.
The results in this thesis show that there is a mild pathology associated with SQPV
infection in grey squirrels. Scabs form at the site of infection but are less proliferative
than in infected red squirrels, though they may still serve to contaminate the
environment with virus leading to further outbreaks of disease. In contrast it seems
likely that the proliferative lesions suffered by red squirrels and the greater amounts
of virus that this leads to are likely to be more significant to the epidemiology of
disease in localised outbreaks
The Wetland Book, Volume I: Structure and Function, Management and Methods
No full textAn edited volume coving all aspects of wetlands, Volume 1 doing as the subtitle suggests: Structure and Function, Management and Methods. Mark Everard has been sole or lead author on 40 chapters in the Wetland Book and junior author in a number of others
The right to silence in the presence of Anton Piller: A question of self incrimination
No full textThe author discusses the advent of Anton Piller orders and contrasts its benefits against the right against self incrimination
Hybrid low-thrust transfers to eight-shaped orbits for polar observation
No full textIn this paper, transfers from low Earth orbit (LEO) to so-called eight-shaped orbits at the collinear libration points in the circular restricted three-body problem are investigated. The potential of these orbits (both natural and sail displaced) for high-latitude observation and telecommunication has recently been established. The transfer is modelled by distinguishing between a near-Earth phase and an interplanetary phase. The near-Earth phase is first assumed to be executed with the Soyuz Fregat upper-stage, which brings the spacecraft from LEO to a highly elliptic orbit. From there, the interplanetary phase is initiated which uses low-thrust propulsion to inject the spacecraft into one of the eight-shaped orbit’s manifolds. Both solar electric propulsion (SEP), solar sailing and hybridised SEP and solar sailing are considered for this phase. The objective is to maximise the mass delivered to the eight-shaped orbit starting from a realistic Soyuz launch vehicle performance into LEO. Optimal trajectories are obtained by solving the optimal control problem in the interplanetary phase with a direct pseudospectral method. The results show that (over the full range of propulsion techniques) 1564 to 1603 kg can be injected into a natural eight-shaped orbit. Within this relatively small range, hybrid propulsion performs best in terms of mass delivered to the eight-shaped orbit, while SEP enables the fastest transfer times. With the interplanetary phase optimised, the upper-stage near-Earth phase is replaced by a multi-revolution low-thrust spiral. Locally optimal control laws for the SEP thruster and solar sail are derived to minimise the time of flight in the spiral. Both pure SEP and hybrid spiral show a significant reduction in the mass required in LEO to deliver the spacecraft to the eight-shaped orbits. While hybrid propulsion did not stand out for the use of an upper-stage near-Earth phase, it does for the use of a low-thrust spiral as it significantly reduces the spiral time with respect to the pure SEP case
A novel method to allow noninvasive, longitudinal imaging of the murine immune system in vivo
No full textIn vivo imaging has revolutionized understanding of the spatiotemporal complexity that subserves the generation of successful effector and regulatory immune responses. Until now, invasive surgery has been required for microscopic access to lymph nodes (LNs), making repeated imaging of the same animal impractical and potentially affecting lymphocyte behavior. To allow longitudinal in vivo imaging, we conceived the novel approach of transplanting LNs into
the mouse ear pinna. Transplanted LNs maintain the structural and cellular organization of conventional secondary lymphoid organs. They participate in lymphocyte
recirculation and exhibit the capacity to receive and respond to local antigenic challenge. The same LN could be repeatedly imaged through time without the requirement for surgical exposure, and the dynamic behavior of the cells within the transplanted LN could be characterized. Crucially, the use of blood vessels as fiducial markers also allowed precise re-registration of the same regions for
longitudinal imaging. Thus, we provide the first demonstration of a method for repeated, noninvasive, in vivo imaging of lymphocyte behavior
Causation in tort law: Back to basics at the Supreme Court of Canada
No full textThis article analyzes the role of causation in Canadian tort law. The author uses the recent Supreme Court of Canada decision of Athey v. Leonati as a model to show how even complex problems of causation can be solved through the application of fundamental principles of tort law: the \"restoration\" principle, the \"take your victim\" principle, and the \"vicissitudes\" principle. The author also demonstrates the importance of distinguishing types of causes based on the following dichotomies: tortious and non-tortious, sufficient and insufficient, and simultaneous and successive. The author argues that applying these principles, and distinguishing causes in this manner, will greatly simplify the resolution of even seemingly complex problems of causation in tort law. | L 'auteur analyse le rdle de la causalitd dans les r~gles de droit applicables aux prijudices au Canada. 11 utilise la d&cision ricente de la Cour supreme du Canada dans Athey c. Leonati pour montrer comment risoudre des problmes de causalitd complexes 6t l'aide de certains principes fondamentaux : le principe de rdtablissement [i Ia situation originale], le principe de Ia vulndrabiliti de la victime et le principe des vicissitudes. L 'auteur dmontre qu 'il est important de distinguer les cas d 'apr~s les dichotomies suivantes : prijudiciable et non prdjudiciable, suffisant et insuffisant, simultang et successif II soutient que l'application de ces principes et de ces distinctions simplifie considirablement la risolution de probldmes de causalitd qui semblent pourtant tris complexes dans ce domaine du droit
A return to first principles in unjust enrichment: Kerr v. Baranow
No full textThe article focuses on the advances made by the Supreme Court of Canada in the law of unjust enrichment on the case of Kerr versus Baranow which was clarified by Cromwell J. by returning to the first principles of unjust enrichment. The author states that the failure of the court to recognize the similarities between resulting trusts and restitution is regrettable. He states that the joint family venture concept of Cromwell J. that is dissociated from unjust enrichment is successful
Enrichments and reasons for restitution: Protecting freedom of choice
No full textThis article analyzes the role of freedom of choice in the Canadian law of unjust enrichment. Courts must balance the plaintiff's interest in recovering a benefit, with which she did not freely part, against the defendant's interest in controlling the allocation of resources in his possession. The primary means of resolving this tension lies in the element of enrichment: The defendant will not be considered legally enriched unless he either chose to assume financial responsibility for the benefit that he received from the plaintiff or, in the circumstances, had no choice to make. The author argues that, since the defendant's autonomy is sufficiently protected by the element of enrichment, the courts should not additionally protect that same interest when formulating the reasons for restitution at the third stage of the unjust enrichment analysis. Liability generally should be strict-it should be triggered by the plaintiff's lack of intention. Decisions that premise liability upon a \"special relationship\" or \"knowing receipt\" unduly favour the defendant's interests and therefore should be reconsidered by Canadian courts
BMP Global Distributions Inc. v. Bank of Nova Scotia: The unitary action in unjust enrichment
No full textIn this article, the author discusses the decision of the Supreme Court of Canada on the unjust enrichment case BMP Global Distribution Inc. v. Bank of Nova Scotia. It states that the Supreme Court have granted the Bank of Nova Scotia the right to restitution following the mistaken payments, forged cheques, and unjust enrichment violations committed by the BMP Global principals. It notes that the Supreme Court's decision only demonstrates that restitution is triggered by unjust enrichment
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