1,474 research outputs found
Fate of the first traversible wormhole: black-hole collapse or inflationary expansion
We study numerically the stability of Morris & Thorne's first traversible
wormhole, shown previously by Ellis to be a solution for a massless ghost
Klein-Gordon field. Our code uses a dual-null formulation for spherically
symmetric space-time integration, and the numerical range covers both universes
connected by the wormhole. We observe that the wormhole is unstable against
Gaussian pulses in either exotic or normal massless Klein-Gordon fields. The
wormhole throat suffers a bifurcation of horizons and either explodes to form
an inflationary universe or collapses to a black hole, if the total input
energy is respectively negative or positive. As the perturbations become small
in total energy, there is evidence for critical solutions with a certain
black-hole mass or Hubble constant. The collapse time is related to the initial
energy with an apparently universal critical exponent. For normal matter, such
as a traveller traversing the wormhole, collapse to a black hole always
results. However, carefully balanced additional ghost radiation can maintain
the wormhole for a limited time. The black-hole formation from a traversible
wormhole confirms the recently proposed duality between them. The inflationary
case provides a mechanism for inflating, to macroscopic size, a Planck-sized
wormhole formed in space-time foam.Comment: 10 pages, RevTeX4, 11 figures, epsf.st
Insecticide Efficacy Against Trimen’s False Tiger Moth, Agoma trimenii (Lepidoptera: Agaristidae)
Trimen’s false tiger moth, Agoma trimenii (Lepidoptera: Agaristidae), has developed pest status in vineyardsin the Northern Cape and Groblersdal areas of South Africa, and an integrated pest management system isrequired. The objective of this study was to test the susceptibility of A. trimenii larvae to three commercialproducts (Delegate®WG, Steward®150 EC and three doses of DiPel® DF). Bioassay tests using all threeproducts, and semi-field trials to test the potential of DiPel® DF against A. trimenii larvae, applied at differentwater volumes (50 g/1 000 L/ha and 50 g/1 430 L/ha) were performed. The residual activity of DiPel® DF,when applied at different water volumes, was investigated daily. Delegate® WG, Steward®150 EC and therecommended dose of DiPel® DF showed 100% larval mortality within seven days. Delegate® WG and therecommended dose of DiPel® DF proved to be the fastest acting products. The product label recommendeddose of DiPel® DF (0.25 g/500 mL distilled water) proved the most effective dose (in comparison to halvedand doubled dosages) and showed 100% mortality five days after application. Increasing the water volumeper ha of a spray application of DiPel® DF for the same application area, showed no significant increasein larval mortality. A reduction in insecticidal activity for DiPel® DF applied at both water volumes wasseen between leaves picked four days after spraying and leaves picked five days after spraying, and nomortality was observed after day 6. To help improve efficacy, attention should be given to increasing spraycoverage and residual activity of DiPel® DF, as well as using all tested products within an integrated pestmanagement system
A Review of Trimen’s False Tiger Moth, Agoma trimenii (Lepidoptera: Agaristidae): Seasonal Biology, Potential Monitoring and Control Techniques
Trimen’s false tiger moth, Agoma trimenii (Lepidoptera: Agaristidae), has recently been found to occur in vineyards in the Northern Cape and Limpopo (Groblersdal area) provinces of South Africa. As little is known about the biology and behaviour of the moth, no official monitoring methods or economic thresholds relating to it, exist. Consequently, management and registered control options still require development. The first aim in the current review, was to gather and critically discuss all the available information on A. trimenii in the context of the information gained from field observations conducted in the Northern Cape, South Africa, during the 2016/2017 and 2017/2018 seasons. The paper also includes reporting on field observations made with regard to various aspects of the seasonal life cycle and ecology of A. trimenii, with a view to investigate, in future research, the potential biological control options available. Potential monitoring strategies of A. trimenii in the field were investigated. Various life stages of A. trimenii were identified, peak flight times were established, overlapping generations were determined, and the behavioural traits of all life stages were documented. Ultraviolet blue light traps proved to be the most promising potential monitoring strategy, with the prospect for an A. trimenii pheromone lure holding potential as an alternative monitoring strategy in future. With summarising all current information on A. trimenii, recommendations for growers to monitor and control A. trimenii are presented, towards the development of an integrated pest management system for the moth
Traversable Wormholes Construction in 2+1 Dimensions
We study traversable Lorentzian wormholes in the three-dimensional low energy
string theory by adding some matter source involving a dilaton field. It will
be shown that there are two-different types of wormhole solutions such as BTZ
and black string wormholes depending on the dilaton backgrounds, respectively.
We finally obtain the desirable solutions which confine exotic matter near the
throat of wormhole by adjusting NS charge.Comment: 12 pages, 4 figures, JHEP style, one reference adde
Locating Community among People with Schizophrenia living in a Diverse Urban Environment
Increasing the community participation of people with severe mental illness is a primary goal of recovery-oriented services. Despite this emphasis, the construct of community remains understudied and poorly articulated. This study provides an in-depth examination of the experiences, beliefs, behaviors, and spaces that constitute community participation for a highly diverse group of people with schizophrenia who are urban dwellers. An in-depth, longitudinal qualitative design was employed with 30 individuals with schizophrenia residing in inner-city neighborhoods in Canada’s largest city. For these individuals, community participation is a dynamic process, shaped by illness and non-illness-associated social relationships and spaces, self-concept, and the resources accessible to the person. The complexity of factors that are associated with “community” for people with schizophrenia, with overlays of culture, poverty, victimization, and discrimination, calls for a critical examination of the community rhetoric employed in practice and policy contexts
EdShare: towards sharing resources for learning and teaching at the University of Southampton
At the University of Southampton, in the UK, we have been developing the Research Repository (e-Prints Soton) since 2005, to showcase the research output and make it more accessible. As a significant next step, the University has taken the strategic decision to develop a repository for educational materials. In developing EdShare at Southampton, we are promoting a cultural shift to a more open and collaborative approach to scholarship as well as research.Successful implementation in such a context requires a lightweight and very simple approach to sharing content facilitated by web 2.0 functionality.<br/
Inability to sustain intraphagolysosomal killing of Staphylococcus aureus predisposes to bacterial persistence in macrophages
Macrophages are critical effectors of the early innate response to bacteria in tissues. Phagocytosis and killing of bacteria are interrelated functions essential for bacterial clearance but the rate-limiting step when macrophages are challenged with large numbers of the major medical pathogen Staphylococcus aureus is unknown. We show that macrophages have a finite capacity for intracellular killing and fail to match sustained phagocytosis with sustained microbial killing when exposed to large inocula of S. aureus (Newman, SH1000 and USA300 strains). S. aureus ingestion by macrophages is associated with a rapid decline in bacterial viability immediately after phagocytosis. However, not all bacteria are killed in the phagolysosome, and we demonstrate reduced acidification of the phagolysosome, associated with failure of phagolysosomal maturation and reduced activation of cathepsin D. This results in accumulation of viable intracellular bacteria in macrophages. We show macrophages fail to engage apoptosis-associated bacterial killing. Ultittop mately macrophages with viable bacteria undergo cell lysis, and viable bacteria are released and can be internalized by other macrophages. We show that cycles of lysis and reuptake maintain a pool of viable intracellular bacteria over time when killing is overwhelmed and demonstrate intracellular persistence in alveolar macrophages in the lungs in a murine model
Motion of Inertial Observers Through Negative Energy
Recent research has indicated that negative energy fluxes due to quantum
coherence effects obey uncertainty principle-type inequalities of the form
|\Delta E|\,{\Delta \tau} \lprox 1\,. Here is the magnitude of
the negative energy which is transmitted on a timescale . Our main
focus in this paper is on negative energy fluxes which are produced by the
motion of observers through static negative energy regions. We find that
although a quantum inequality appears to be satisfied for radially moving
geodesic observers in two and four-dimensional black hole spacetimes, an
observer orbiting close to a black hole will see a constant negative energy
flux. In addition, we show that inertial observers moving slowly through the
Casimir vacuum can achieve arbitrarily large violations of the inequality. It
seems likely that, in general, these types of negative energy fluxes are not
constrained by inequalities on the magnitude and duration of the flux. We
construct a model of a non-gravitational stress-energy detector, which is
rapidly switched on and off, and discuss the strengths and weaknesses of such a
detector.Comment: 18pp + 1 figure(not included, available on request), in LATEX,
TUPT-93-
Multi-Donor longitudinal antibody repertoire sequencing reveals the existence of public antibody clonotypes in HIV-1 infection
Characterization of single antibody lineages within infected individuals has provided insights into the development of Env-specific antibodies. However, a systems-level understanding of the humoral response against HIV-1 is limited. Here, we interrogated the antibody repertoires of multiple HIV-infected donors from an infection-naive state through acute and chronic infection using next-generation sequencing. This analysis revealed the existence of “public” antibody clonotypes that were shared among multiple HIV-infected individuals. The HIV-1 reactivity for representative antibodies from an identified public clonotype shared by three donors was confirmed. Furthermore, a meta-analysis of publicly available antibody repertoire sequencing datasets revealed antibodies with high sequence identity to known HIV-reactive antibodies, even in repertoires that were reported to be HIV naive. The discovery of public antibody clonotypes in HIV-infected individuals represents an avenue of significant potential for better understanding antibody responses to HIV-1 infection, as well as for clonotype-specific vaccine development
The Quantum Interest Conjecture
Although quantum field theory allows local negative energy densities and
fluxes, it also places severe restrictions upon the magnitude and extent of the
negative energy. The restrictions take the form of quantum inequalities. These
inequalities imply that a pulse of negative energy must not only be followed by
a compensating pulse of positive energy, but that the temporal separation
between the pulses is inversely proportional to their amplitude. In an earlier
paper we conjectured that there is a further constraint upon a negative and
positive energy delta-function pulse pair. This conjecture (the quantum
interest conjecture) states that a positive energy pulse must overcompensate
the negative energy pulse by an amount which is a monotonically increasing
function of the pulse separation. In the present paper we prove the conjecture
for massless quantized scalar fields in two and four-dimensional flat
spacetime, and show that it is implied by the quantum inequalities.Comment: 17 pages, Latex, 3 figures, uses eps
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