705 research outputs found
Water crisis and institutional adaptive capacity: lessons from the Australian experience
Managing large socio-technical urban water systems will be increasingly challenged under future extreme and uncertain climatic conditions. Reconfiguring these systems to meet this challenge by integrating supply sources and multiplying uses of water is well described from a technical perspective. Adjusting the institutions which frame the management of these systems, enabling adaptive governance of water resources, is not well operationalized. This study seeks to address this gap through an institutional analysis of the case of Perth, Australia, a city where extreme drought has driven the adoption of new management practices. The institutional dynamics underlying these changes were explored to gain insight into how adaptive capacity might be mobilised to implement Integrated Urban Water Management (IUWM). The study found Perth’s institutional adaptive capacity, like other cities, is still largely limited. The new practices buffered water scarcity, but have not yet shifted the system toward a more adaptable configuration. The absence of certain rules within and between levels of the institutional setting which enable flexibility appear to leave conditions for ongoing adaptation unmet. This analysis suggests that to address the widely acknowledged failure of mainstream implementation of IUWM, a deeper understanding of institutional dynamics that create systemic change is needed
Water scarcity and institutional change: lessons in adaptive governance from the drought experience of Perth, Western Australia
Urban water systems will be increasingly challenged under future climates and global pressures. Meeting challenges by reconfiguring water systems to integrate supplies and deliver multifunctional uses is technically well described. Adjusting the institutions that frame the management of these systems is not well operationalized in practice or conceptualized in theory. This study seeks to address this gap through an institutional analysis of Perth, Australia, a city where drought crisis has put under pressure both management practices and the institutional setting that underlies them. The study found that while trusted practices moderated water scarcity, the stability of the institutional setting may not facilitate a shift toward adaptable institutional configurations suited to future conditions. The results identified three key ingredients for a flexible institutional setting: (i) feedbacks in the system through better information management, (ii) reflexive dialogue and strategic use of projects to generate greater learning opportunities, and (iii) policy level support for sector-wide collaboration through progressive agendas, incentives for innovation and capacity building in stakeholder and community engagement. Further, the results suggest that a deeper understanding of institutional dynamics is needed to enable adaptive governance. The paper provides an analytical framework for diagnosing how greater adaptive capacity might be mobilized through influencing these dynamics
Rates for the reactions antiproton-proton --> pi phi and gamma phi
We study antiproton-proton annihilation at rest into and
. Rescattering by and
for states is sizable, of
order in the branching ratio, but
smaller than experiment. For the
rescattering contributions are negligible, but the channel is well
explained by a intermediate state combined with vector meson
dominance.Comment: 12 pages, plain latex, 2 postscript figures available upon request,
PSI-PR-93-2
Study of a zirconium getter for purification of xenon gas
Oxygen, nitrogen and methane purification efficiencies for a common zirconium
getter are measured in 1050 Torr of xenon gas. Starting with impurity
concentrations near 10^{-6} g/g, the outlet impurity level is found to be less
than 120*10^{-12} g/g for O2 and less than 950*10^{-12} g/g for N2. For methane
we find residual contamination of the purified gas at concentrations varying
over three orders of magnitude, depending on the purifier temperature and the
gas flow rate. A slight reduction in the purifier's methane efficiency is
observed after 13 mg of this impurity has been absorbed, which we attribute to
partial exhaustion of the purifier's capacity for this species. We also find
that the purifier's ability to absorb N2 and methane can be extinguished long
before any decrease in O2 performance is observed, and slower flow rates should
be employed for xenon purification due to the cooling effect that the heavy gas
has on the getter.Comment: 14 pages, 5 figure
Quantum Conductance in Silver Nanowires: correlation between atomic structure and transport properties
We have analyzed the atomic arrangements and quantum conductance of silver
nanowires generated by mechanical elongation. The surface properties of Ag
induce unexpected structural properties, as for example, predominance of high
aspect ratio rod-like wires. The structural behavior was used to understand the
Ag quantum conductance data and the proposed correlation was confirmed by means
of theoretical calculations. These results emphasize that the conductance of
metal point contacts is determined by the preferred atomic structures and, that
atomistic descriptions are essential to interpret the quantum transport
behavior of metal nanostructures.Comment: 4 pages, 4 figure
Observation of the Smallest Metal Nanotube with Square-cross-section
Understanding the mechanical properties of nanoscale systems requires a range
of measurement techniques and theoretical approaches to gather the relevant
physical and chemical information. The arrangements of atoms in nanostructures
and macroscopic matter can be different, principally due to the role of surface
energy, but the interplay between atomic and electronic structure in
association with applied mechanical stress can also lead to surprising
differences. For example, metastable structures such as suspended chains of
atoms and helical wires have been produced by the stretching of metal
junctions. Here we report the spontaneous formation of the smallest possible
metal nanotube with a square cross-section during the elongation of silver
nanocontacts. Ab initio calculations and molecular simulations indicate that
the hollow wire forms because this configuration allows the surface energy to
be minimized, and also generates a soft structure capable of absorbing a huge
tensile deformation
On the Optimum Long Baseline for the Next Generation Neutrino Oscillation Experiments
For high energy long baseline neutrino oscillation experiments, we propose a
Figure of Merit criterion to compare the statistical quality of experiments at
various oscillation distances under the condition of identical detectors and a
given neutrino beam. We take into account all possible experimental errors
under general consideration. In this way the Figure of Merit is closely related
to the usual statistical criterion of number of sigmas. We use a realistic
neutrino beam for an entry level neutrino factory and a possible superbeam from
a meson source and a 100 kt detector for the calculation. We considered in
detail four oscillation distances, 300 km, 700 km, 2100 km and 3000 km, in the
neutrino energy range of 0.5-20 GeV for a 20 GeV entry level neutrino factory
and a 50 GeV superbeam. We found that the very long baselines of 2100 km and
3000 km are preferred for the neutrino factory according to the figure of merit
criterion. Our results also show that, for a neutrino factory, lower primary
muon energies such as 20 GeV are preferred rather than higher ones such as 30
or 50 GeV. For the superbeam, the combination of a long baseline such as 300 km
and a very long baseline like 2100 km will form a complete measurement of the
oscillation parameters besides the CP phase. To measure the CP phase in a
superbeam, a larger detector (a factor 3 beyond what is considered in this
article) and/or a higher intensity beam will be needed to put some significant
constraints on the size of the CP angle.Comment: 21 LaTeX pages, 13 PS figures, typos corrected, references adde
A New Linear Logic for Deadlock-Free Session-Typed Processes
The π -calculus, viewed as a core concurrent programming language, has been used as the target of much research on type systems for concurrency. In this paper we propose a new type system for deadlock-free session-typed π -calculus processes, by integrating two separate lines of work. The first is the propositions-as-types approach by Caires and Pfenning, which provides a linear logic foundation for session types and guarantees deadlock-freedom by forbidding cyclic process connections. The second is Kobayashi’s approach in which types are annotated with priorities so that the type system can check whether or not processes contain genuine cyclic dependencies between communication operations. We combine these two techniques for the first time, and define a new and more expressive variant of classical linear logic with a proof assignment that gives a session type system with Kobayashi-style priorities. This can be seen in three ways: (i) as a new linear logic in which cyclic structures can be derived and a CYCLE -elimination theorem generalises CUT -elimination; (ii) as a logically-based session type system, which is more expressive than Caires and Pfenning’s; (iii) as a logical foundation for Kobayashi’s system, bringing it into the sphere of the propositions-as-types paradigm
PW06-05 The predictive role of anxiety disorders on depressive phenomenology during post-partum period
Aims:To investigate the predictive role of any specific (DSM-IV) Anxiety Disorders (AD) on depressive symptoms and Major or Minor Depressive Disorder (MDD, mDD) during early postpartum period.Method:Women (at the 12th-15th gestational week, N=1066) were recruited in the framework of the Program 'Perinatal Depression - Research & Screening Unit (PND-ReScU)". Depressive symptoms were assessed by the Edinburgh Postnatal Depression Scale (EPDS), and Axis-I disorders (AD, MDD, mDD) were diagnosed with the Structured Clinical Interview for Axis-I Disorders (SCID-I).Results:Any current AD at baseline (3rd month of pregnancy) was detected in 231 (21.7%). Having at least one current AD, was associated with a greater likelihood of having MDD or mDD during the early postpartum period, even after the adjustment for the confounding factor of having a lifetime history of MDD (RR=3.86 95%CI 1.58-9.42).In particular, women affected by Obsessive Compulsive Disorder (N=17; 1.6%) or Panic Disorder (N=43; 4%) had at higher risk to develop depressive symptoms (EPDS≥13) during the postpartum period than women without these AD (RR=6.9 and 6.7 respectively). As for the risk of developing PPD, the strongest association was found for women with Panic Disorder (RR=7.6 95% CI 2.62-22.0).Conclusions:AD are associated with a greater likelihood to develop depressive symptoms and MDD or mDD during the early postpartum period. Women with current PD have the strongest risk to develop both MDD or mDD and depressive symptoms during early postpartum period compared to other anxiety disorders
Early growth response gene-2 (Egr-2) regulates the development of B and T cells
The study was supported by Arthritis Research UK.
Copyright @ 2011 Li et al.BACKGROUND: Understanding of how transcription factors are involved in lymphocyte development still remains a challenge. It has been shown that Egr-2 deficiency results in impaired NKT cell development and defective positive selection of T cells. Here we investigated the development of T, B and NKT cells in Egr-2 transgenic mice and the roles in the regulation of distinct stages of B and T cell development. METHODS AND FINDINGS: The expression of Egr1, 2 and 3 were analysed at different stages of T and B cell development by RT-PCT and results showed that the expression was strictly regulated at different stages. Forced expression of Egr-2 in CD2+ lymphocytes resulted in a severe reduction of CD4+CD8+ (DP) cells in thymus and pro-B cells in bone marrow, which was associated with reduced expression of Notch1 in ISP thymocytes and Pax5 in pro-B cells, suggesting that retraction of Egr-2 at the ISP and pro-B cell stages is important for the activation of lineage differentiation programs. In contrast to reduction of DP and pro-B cells, Egr-2 enhanced the maturation of DP cells into single positive (SP) T and NKT cells in thymus, and immature B cells into mature B cells in bone marrow. CONCLUSIONS: Our results demonstrate that Egr-2 expressed in restricted stages of lymphocyte development plays a dynamic, but similar role for the development of T, NKT and B cells.This article is provided by the Brunel Open Access publishing fund
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