6,875 research outputs found
Functorial properties of Putnam's homology theory for Smale spaces
We investigate functorial properties of Putnam's homology theory for Smale
spaces. Our analysis shows that the addition of a conjugacy condition is
necessary to ensure functoriality. Several examples are discussed that
elucidate the need for our additional hypotheses. Our second main result is a
natural generalization of Putnam's Pullback Lemma from shifts of finite type to
non-wandering Smale spaces.Comment: Updated to agree with published versio
A direct proof of Kim's identities
As a by-product of a finite-size Bethe Ansatz calculation in statistical
mechanics, Doochul Kim has established, by an indirect route, three
mathematical identities rather similar to the conjugate modulus relations
satisfied by the elliptic theta constants. However, they contain factors like
and , instead of . We show here that
there is a fourth relation that naturally completes the set, in much the same
way that there are four relations for the four elliptic theta functions. We
derive all of them directly by proving and using a specialization of
Weierstrass' factorization theorem in complex variable theory.Comment: Latex, 6 pages, accepted by J. Physics
After 'Black Saturday': adapting to bushfires in a changing climate
Abstract not availabl
Vulnerability to bushfires in rural Australia: a case study from East Gippsland, Victoria
This paper investigates the nature and causes of vulnerability to bushfires in the Wulgulmerang district of East Gippsland, Victoria, in south-eastern Australia. In 2003 bushfires devastated the small population of this isolated farming district, destroying homes, agricultural assets and public infrastructure. The ?res also adversely affected the health, livelihoods and social lives of many local people. The paper examines: (i) how and why people were exposed to hazards during the bushfires; and (ii) how and why people were differentially capable of coping and adapting to the fires' impacts. Qualitative methods were primarily used to investigate these questions, including semi-structured interviews with residents and landholders of the district and others who responded to the fires in an official or unofficial capacity. Vulnerability is shown to arise from the circumstances of people's everyday lives, which are shaped by factors both within and beyond their control. Local pressures and challenges such as drought, declining farm incomes, depopulation, and the inaccessibility of essential services e are shown to increase people's exposure to hazards and reduce their capacities to cope and adapt. The paper demonstrates the fundamental importance of sustainable livelihoods and regional economic vitality to the long-term goal of vulnerability reduction
The Poisson-Boltzmann Theory for Two Parallel Uniformly Charged Plates
We solve the nonlinear Poisson-Boltzmann equation for two parallel and likely
charged plates both inside a symmetric elecrolyte, and inside a 2 : 1
asymmetric electrolyte, in terms of Weierstrass elliptic functions. From these
solutions we derive the functional relation between the surface charge density,
the plate separation, and the pressure between plates. For the one plate
problem, we obtain exact expressions for the electrostatic potential and for
the renormalized surface charge density, both in symmetric and in asymmetric
electrolytes. For the two plate problems, we obtain new exact asymptotic
results in various regimes.Comment: 17 pages, 9 eps figure
A peptide with N-terminal histidine and C-terminal isoleucine amide (PHI) and vasoactive intestinal peptide (VIP) are copackaged in myenteric neurones of the guinea pig ileum.
When cytoplasmic extracts of the myenteric plexus of guinea pig ileum are submitted to centrifugal density gradient separation in a zonal rotor, conditions which separate storage particles containing substance P, somatostatin and VIP from each other, PHI copurifies with VIP. The two immunoreactivities cannot be separated by particle exclusion chromatography, which depends on size rather than density. It is concluded that the posttranslational cleavage of the propeptide or precursor to PHI and VIP occurs after packaging into these storage particles
What makes re-finding information difficult? A study of email re-finding
Re-nding information that has been seen or accessed before is a task which can be relatively straight-forward, but often it can be extremely challenging, time-consuming and frustrating. Little is known, however, about what makes one re-finding task harder or easier than another. We performed a user study to learn about the contextual factors that influence users' perception of task diculty in the context of re-finding email messages. 21 participants were issued re-nding tasks to perform on their own personal collections. The participants' responses to questions about the tasks combined with demographic data and collection statistics for the experimental population provide a rich basis to investigate the variables that can influence the perception of diculty. A logistic regression model was developed to examine the relationships be- tween variables and determine whether any factors were associated with perceived task diculty. The model reveals strong relationships between diculty and the time lapsed since a message was read, remembering when the sought-after email was sent, remembering other recipients of the email, the experience of the user and the user's ling strategy. We discuss what these findings mean for the design of re-nding interfaces and future re-finding research
Understanding of the Renormalization Program in a mathematically Rigorous Framework and an Intrinsic Mass Scale
we show there exists a mathematically consistent framework in which the
Renormalization Program can be understood in a natural manner. The framework
does not require any violations of mathematical rigor usually associated with
the Renormalization program. We use the framework of the non-local field
theories [these carry a finite mass scale (\Lambda)]and set up a finite
perturbative program. We show how this program leads to the perturbation series
of the usual renormalization program [except one difference] if the series is
restructured .We further show that the comparison becomes possible if there
exists a finite mass scale (\Lambda), with certain properties, in the Quantum
Field theory [which we take to be the scale present in the nonlocal theory]. We
give a way to estimate the scale (\Lambda). We also show that the finite
perturbation program differs from the usual renormalization program by a term;
which we propose can also be used to put a bound on (\Lambda).Comment: 19 pages, a missing equation added,a reference added and a few typos
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