2,337 research outputs found
Erosion of trust in humanitarian agencies: what strategies might help?
Aid agencies (AAs) provide a range of humanitarian and health related assistance globally. However, the trust placed on them is eroding. Evidence for this includes accusations of a decline in their humanitarianism, and the increasing number of conflicts with host states. An analysis of the concerns expressed yields two possible reasons: a relative lack of transparency of their work and weak accountability mechanisms. This is further supported by the existing milieu: an absence of internationally accepted instrument or mechanism to check the credentials of INGOs and an opaque system of close links between some of the INGOs and their donors. The article suggests two global strategies to tackle these issues: (a) Increase transparency by establishing a global register of aid agencies. This should have basic information: their main goals and activities, countries they are active in, number of employees, annual turnover of funds (updated regularly), principal financing sources and nature of links with donors. This could also be available as printed manual that should be freely available to client countries. (b) Ensure accountability by developing templates of fair legal instruments (to facilitate and regulate work), and a set of generic rules and procedures of engagement for the interactions between agencies and client states. These should be institutionalized within the regulatory frameworks of countries and included in the Codes of Conduct of NGOs
Transition to superfluid turbulence governed by an intrinsic parameter
Hydrodynamic flow in both classical and quantum fluids can be either laminar
or turbulent. To describe the latter, vortices in turbulent flow are modelled
with stable vortex filaments. While this is an idealization in classical
fluids, vortices are real topologically stable quantized objects in
superfluids. Thus superfluid turbulence is thought to hold the key to new
understanding on turbulence in general. The fermion superfluid 3He offers
further possibilities owing to a large variation in its hydrodynamic
characteristics over the experimentally accessible temperatures. While studying
the hydrodynamics of the B phase of superfluid 3He, we discovered a sharp
transition at 0.60Tc between two regimes, with regular behaviour at
high-temperatures and turbulence at low-temperatures. Unlike in classical
fluids, this transition is insensitive to velocity and occurs at a temperature
where the dissipative vortex damping drops below a critical limit. This
discovery resolves the conflict between existing high- and low-temperature
measurements in 3He-B: At high temperatures in rotating flow a vortex loop
injected into superflow has been observed to expand monotonically to a single
rectilinear vortex line, while at very low temperatures a tangled network of
quantized vortex lines can be generated in a quiescent bath with a vibrating
wire. The solution of this conflict reveals a new intrinsic criterion for the
existence of superfluid turbulence.Comment: Revtex file; 5 pages, 2 figure
The Diffusion of Humans and Cultures in the Course of the Spread of Farming
The most profound change in the relationship between humans and their
environment was the introduction of agriculture and pastoralism. [....] For an
understanding of the expansion process, it appears appropriate to apply a
diffusive model. Broadly, these numerical modeling approaches can be catego-
rized in correlative, continuous and discrete. Common to all approaches is the
comparison to collections of radiocarbon data that show the apparent wave of
advance of the transition to farming. However, these data sets differ in entry
density and data quality. Often they disregard local and regional specifics and
research gaps, or dating uncertainties. Thus, most of these data bases may only
be used on a very general, broad scale. One of the pitfalls of using
irregularly spaced or irregularly documented radiocarbon data becomes evident
from the map generated by Fort (this volume, Chapter 16): while the general
east-west and south-north trends become evident, some areas appear as having
undergone anomalously early transitions to farming. This may be due to faulty
entries into the data base or regional problems with radiocarbon dating, if not
unnoticed or undocumented laboratory mistakes.Comment: 20 pages, 5 figures, submitted to Diffusive Spreading in Nature,
Technology and Society, edited by Armin Bunde, J\"urgen Caro, J\"org
K\"arger, Gero Vogl, Chapter 1
Mathematizing Darwin
Ernst Mayr called the first part of the evolutionary synthesis the ‘Fisherian synthesis’ on account of the dominant role played by R.A. Fisher in forging a mathematical theory of natural selection together with J.B.S. Haldane and Sewall Wright in the decade 1922–1932. It is here argued that Fisher’s contribution relied on a close reading of Darwin’s work to a much greater extent than did the contributions of Haldane and Wright, that it was synthetic in contrast to their analytic approach and that it was greatly influenced by his friendship with the Darwin family, particularly with Charles’s son Leonard
Phase-slip induced dissipation in an atomic Bose-Hubbard system
Phase slips play a primary role in dissipation across a wide spectrum of
bosonic systems, from determining the critical velocity of superfluid helium to
generating resistance in thin superconducting wires. This subject has also
inspired much technological interest, largely motivated by applications
involving nanoscale superconducting circuit elements, e.g., standards based on
quantum phase-slip junctions. While phase slips caused by thermal fluctuations
at high temperatures are well understood, controversy remains over the role of
phase slips in small-scale superconductors. In solids, problems such as
uncontrolled noise sources and disorder complicate the study and application of
phase slips. Here we show that phase slips can lead to dissipation for a clean
and well-characterized Bose-Hubbard (BH) system by experimentally studying
transport using ultra-cold atoms trapped in an optical lattice. In contrast to
previous work, we explore a low velocity regime described by the 3D BH model
which is not affected by instabilities, and we measure the effect of
temperature on the dissipation strength. We show that the damping rate of
atomic motion-the analogue of electrical resistance in a solid-in the confining
parabolic potential fits well to a model that includes finite damping at zero
temperature. The low-temperature behaviour is consistent with the theory of
quantum tunnelling of phase slips, while at higher temperatures a cross-over
consistent with the transition to thermal activation of phase slips is evident.
Motion-induced features reminiscent of vortices and vortex rings associated
with phase slips are also observed in time-of-flight imaging.Comment: published in Nature 453, 76 (2008
Selective-logging and oil palm: Multitaxon impacts, biodiversity indicators, and trade-offs for conservation planning
Strong global demand for tropical timber and agricultural products has driven large-scale logging and subsequent conversion of tropical forests. Given that the majority of tropical landscapes have been or will likely be logged, the protection of biodiversity within tropical forests thus depends on whether species can persist in these economically exploited lands, and if species cannot persist, whether we can protect enough primary forest from logging and conversion. However, our knowledge of the impact of logging and conversion on biodiversity is limited to a few taxa, often sampled in different locations with complex land-use histories, hampering attempts to plan cost-effective conservation strategies and to draw conclusions across taxa. Spanning a land-use gradient of primary forest, once- and twice-logged forests, and oil palm plantations, we used traditional sampling and DNA metabarcoding to compile an extensive data set in Sabah, Malaysian Borneo for nine vertebrate and invertebrate taxa to quantify the biological impacts of logging and oil palm, develop cost-effective methods of protecting biodiversity, and examine whether there is congruence in response among taxa. Logged forests retained high species richness, including, on average, 70% of species found in primary forest. In contrast, conversion to oil palm dramatically reduces species richness, with significantly fewer primary-forest species than found on logged forest transects for seven taxa.Using a systematic conservation planning analysis, we show that efficient protection of primary-forest species is achieved with land portfolios that include a large proportion of logged-forest plots. Protecting logged forests is thus a cost-effective method of protecting an ecologically and taxonomically diverse range of species, particularly when conservation budgets are limited. Six indicator groups (birds, leaf-litter ants, beetles, aerial hymenopterans, flies, and true bugs) proved to be consistently good predictors of the response of the other taxa to logging and oil palm. Our results confidently establish the high conservation value of logged forests and the low value of oil palm. Cross-taxon congruence in responses to disturbance also suggests that the practice of focusing on key indicator taxa yields important information of general biodiversity in studies of logging and oil palm
Invasion speeds for structured populations in fluctuating environments
We live in a time where climate models predict future increases in
environmental variability and biological invasions are becoming increasingly
frequent. A key to developing effective responses to biological invasions in
increasingly variable environments will be estimates of their rates of spatial
spread and the associated uncertainty of these estimates. Using stochastic,
stage-structured, integro-difference equation models, we show analytically that
invasion speeds are asymptotically normally distributed with a variance that
decreases in time. We apply our methods to a simple juvenile-adult model with
stochastic variation in reproduction and an illustrative example with published
data for the perennial herb, \emph{Calathea ovandensis}. These examples
buttressed by additional analysis reveal that increased variability in vital
rates simultaneously slow down invasions yet generate greater uncertainty about
rates of spatial spread. Moreover, while temporal autocorrelations in vital
rates inflate variability in invasion speeds, the effect of these
autocorrelations on the average invasion speed can be positive or negative
depending on life history traits and how well vital rates ``remember'' the
past
Letrozole as upfront endocrine therapy for postmenopausal women with hormone-sensitive breast cancer: BIG 1-98
The BIG 1-98 trial is a large, randomized, independently conducted clinical trial designed to compare the efficacy of upfront letrozole versus tamoxifen monotherapy and to compare sequential or up-front use of letrozole and/or tamoxifen as an early adjuvant therapy for patients with early breast cancer. We report on the results from the primary core analysis of the BIG 1-98 trial of 8,010 patients, which compares monotherapy with letrozole versus tamoxifen. This pre-planned core analysis allowed the use of patient data from the monotherapy arms of letrozole and tamoxifen and from the sequential arms prior to the drug switch point. Patients randomized to letrozole had a 19% improved disease-free survival (hazard ratio [HR] = 0.81; P = 0.003), due especially to reduced distant metastases (HR = 0.73; P = 0.001). A 14% risk reduction of fatal events in favor of letrozole was also observed (P = NS). The results from the monotherapy arms alone confirmed the findings from the primary core analysis. Based on the results from this trial, the aromatase inhibitor letrozole (Femara®) is currently recommended as a part of standard adjuvant therapy for postmenopausal women with endocrine-responsive breast cancer and has recently been approved in the early adjuvant setting in both Europe and the United States. A subsequent analysis after additional follow-up will address the question of monotherapy versus sequential therapy
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