1,897 research outputs found
Mechanism for the formation of the high-altitude stagnant cusp: Cluster and SuperDARN observations
On 16 March 2002, Cluster moved from nightside to dayside, across the high-altitude northern cusp during an extended period of relatively steady positive IMF BY and BZ. Combined Cluster and SuperDARN data imply the existence of two reconnection sites: in the high- latitude northern hemisphere dusk and southern hemisphere dawn sectors. Within the cusp, Cluster encounters 3 distinct plasma regions. First, injections of magnetosheath-like plasma associated with dawnward and sunward convection suggest Cluster crosses newly- reconnected field lines related to the dusk reconnection site. Second, Cluster observes a Stagnant Exterior Cusp (SEC), characterized by nearly isotropic and stagnant plasma. Finally, Cluster crosses a region with significant antifield-aligned flows. We suggest the observed SEC may be located on newly re-closed field lines, reconnected first poleward of the northern hemisphere cusp and later reconnected again poleward of the southern hemisphere cusp. We discuss how the Cluster observations correspond to expectations of ’double reconnection’ model
Rich Cluster and Non-Cluster Radio Galaxies & the (P,D) Diagram for a Large Number of FR I and FR II Sources
We present a comparison of the optical and radio properties of radio sources
inside and outside the cores of rich clusters from combined samples of more
than 380 radio sources. We also examine the nature of FR I and FR II host
galaxies, and in particular, we illustrate the importance of selection effects
in propagating the misconception that FR I's and FR II's are found in hosts of
very different optical luminosity. Given the large sample size, we also discuss
the power-size (P,D) distributions as a function of optical luminosity.Comment: to appear in Life Cycles of Radio Galaxies, ed. J. Biretta et al.,
New Astronomy Reviews; 6 pages, including 2 figure
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Implementing the UN Action Programme for Combating the Illicit Trafficking in Small Arms and Light Weapons in All Its Aspects.
yesHistorically, UN conferences have been criticised for resulting more in compromises than in
commitments to real change, which is also a charge that has been levelled against the UN
Conference on the Illicit Trade in Small Arms and Light Weapons in All Its Aspects (UN Small
Arms Conference). The consensus-based approach adopted throughout the negotiations had
the advantage of binding all participating States to all aspects of the agreed Programme of
Action (PoA), but it also ensured that it would be difficult to achieve a sufficiently rigorous and
comprehensive agreement on all of the measures required to tackle the trafficking,
proliferation and misuse of small arms and light weapons (SALW). Therefore, in spite of the
efforts of many governments and NGOs, the UN Small Arms Conference did not agree
sufficiently robust agreements in several areas. Nonetheless, it was a valuable and productive
process. The resulting PoA includes a reasonably comprehensive set of key principles and
commitments, which provide a basis for taking forward action at national, regional and global
levels. The PoAwas agreed by all of the participating States, amounting to more than 100,
and each are politically bound to adopt and implement it.
Given that the UN Small Arms Conference was the first of its kind, its achievement in
generating political will and momentum for efforts to control SALW is important. Although
many of the commitments are weaker and less comprehensive than hoped for by many
governments and organisations, it is significant that the PoAcontains at least some important
commitments in all but two of the `coreÂż issue areas raised by States. The two exceptions
relate to transfers to non-State actors and to civilian trade, possession and use of SALW,
restrictions which were strongly opposed by the USA. Equally, human rights related issues
were noteworthy by their absence in the PoA.
Whilst the process of reaching agreement began with a far-reaching draft PoA in December
2000 (A/Conf.192/L.4), most of the comments that were tabled on this text during the second
Preparatory Committee in January 2001 came from countries that sought to weaken its
commitments. The subsequent draft (A/Conf.192/L.4/Rev.1) was therefore weaker, with the
result that progressive States faced an uphill task in seeking to strengthen its provisions.
The next draft PoA emerged at the UN Small Arms Conference itself in the form of a third draft
(A/Conf.192/L.5). Although still limited in a number of key areas Âż such as export criteria and
transparency Âż this document went further than L.4/Rev.1 in a number of respects and included
specific international commitments, including on brokering and tracing lines of supply. This,
however, proved too ambitious an agenda for a small group of States and in the end the document
that was adopted by consensus (A/Conf.192/L.5/Rev.1) represented a lower-level compromise.
Despite the difficulties of agreeing the consensus-based PoA, the process culminating in the
agreement was perhaps as important as the agreement itself. UN Small Arms Conference
represented the first time that all UN Member States had met to discuss the illicit trade in SALW
in all its aspects with a view to agreeing a comprehensive set of measures to address the
problem. Although many of the commitments contained in the PoAare couched in equivocal
language that will allow States to do as much or as little as they like, it is clear that the UN Small
Arms Conference has contributed to a much better understanding, amongst all stakeholders, of
the nature of the illicit trade in SALW and of the particular concerns and priorities of different
countries and sub-regions. It is also clear that although the Programme of Action provides a set
of minimum standards and commitments which all states should adopt, it also encourages
further action from all States willing to adopt more stringent commitments and stronger
programmes. There is a willingness among a number of States to build upon the PoAand take
more concrete and far-reaching measures at national, sub-regional, regional and international
levels, such as specific arrangements for tracing co-operation, or mechanisms to co-ordinate
e fforts to improve stockpile security or weapons destruction. This briefing provides a critical assessment of key provisions in the UN Small Arms
Conference PoA. Section 1 measures the overall outcomes of the conference against those
that the Biting the Bullet (BtB) project proposed as optimal conclusions, and suggests ways to
put the commitments contained in the PoA into practice. Section 2 assesses the
implementation and follow-up commitments contained in the PoA, and identifies ways of
promoting the implementation of Sections III and IV, as well as options for making the most of
the Biennial Meetings of States and the Review Conference in 2006. Section 3 examines
funding and resourcing possibilities for the PoA including identifying needs, mobilising
resources and matching needs with resources. The final section of the briefing focuses on the
way forward, and in particular on how implementation of the PoA could build on existing
regional initiatives and develop common international approaches to controlling SALW
proliferation, availability and misuse. It also examines how action to prevent and combat the
illicit trade in SALW in all its aspects can be taken forward at sub-regional and regional levels
in conjunction with all major stakeholders, including civil society, in the period leading up to
the first Review Conference
Time-frequency detection algorithm for gravitational wave bursts
An efficient algorithm is presented for the identification of short bursts of
gravitational radiation in the data from broad-band interferometric detectors.
The algorithm consists of three steps: pixels of the time-frequency
representation of the data that have power above a fixed threshold are first
identified. Clusters of such pixels that conform to a set of rules on their
size and their proximity to other clusters are formed, and a final threshold is
applied on the power integrated over all pixels in such clusters. Formal
arguments are given to support the conjecture that this algorithm is very
efficient for a wide class of signals. A precise model for the false alarm rate
of this algorithm is presented, and it is shown using a number of
representative numerical simulations to be accurate at the 1% level for most
values of the parameters, with maximal error around 10%.Comment: 26 pages, 15 figures, to appear in PR
Evidence for a three-nucleon-force effect in proton-deuteron elastic scattering
Developments in spin-polarized internal targets for storage rings have
permitted measurements of 197 MeV polarized protons scattering from vector
polarized deuterons. This work presents measurements of the polarization
observables A_y, iT_11, and C_y,y in proton-deuteron elastic scattering. When
compared to calculations with and without three-nucleon forces, the
measurements indicate that three-nucleon forces make a significant contribution
to the observables. This work indicates that three-body forces derived from
static nuclear properties appear to be crucial to the description of dynamical
properties.Comment: 8 pages 2 figures Latex, submitted to Phys. Rev. Letter
Rumen physiology constrains diet niche: linking digestive physiology and food selection across wild ruminant species
We propose a hypothesis for digestive constraints on the browsing and grazing options available to ruminants: that the diet-niche range (maximum and minimum grass intake) of a species is dependent upon its predisposition to stratified rumen contents, based on observations that this characteristic is a critical step towards enhanced fibre digestion and greater fluid throughput. We compare a physiological (heterogeneity of ingesta fluid content) and an anatomical (the intraruminal papillation pattern) measure with dietary evidence for a range of African and temperate species. Both measures are strongly related to the mean percentage of grass in species’ natural diets, as well as to the maximum and minimum levels of grass intake, respectively. The nature of these effects implies a stratification-level threshold, below which a species will not use a grass-based diet, but above which grass consumption can increase exponentially. However, above this threshold, a minimum percentage of grass in the diet is a prerequisite for optimal performance. We argue that this second constraint is crucial, as it depicts how a greater fluid throughput reduces potential for detoxification of plant secondary compounds, and therefore limits the maximum amount of browse a stratifying species will consume
Respiratory viruses, symptoms, and inflammatory markers in acute exacerbations and stable chronic obstructive pulmonary disease
The effects of respiratory viral infection on the time course of chronic obstructive pulmonary disease (COPD) exacerbation were examined by monitoring changes in systemic inflammatory markers in stable COPD and at exacerbation. Eighty-three patients with COPD (mean [SD] age, 66.6 [7.1] yr, FEV1, 1.06 [0.61] L) recorded daily peak expiratory flow rate and any increases in respiratory symptoms. Nasal samples and blood were taken for respiratory virus detection by culture, polymerase chain reaction, and serology, and plasma fibrinogen and serum interleukin-6 (IL-6) were determined at stable baseline and exacerbation. Sixty-four percent of exacerbations were associated with a cold occurring up to 18 d before exacerbation. Seventy-seven viruses (39 [58.2%] rhinoviruses) were detected in 66 (39.2%) of 168 COPD exacerbations in 53 (64%) patients. Viral exacerbations were associated with frequent exacerbators, colds with increased dyspnea, a higher total symptom count at presentation, a longer median symptom recovery period of 13 d, and a tendency toward higher plasma fibrinogen and serum IL-6 levels. Non-respiratory syncytial virus (RSV) respiratory viruses were detected in 11 (16%), and RSV in 16 (23.5%), of 68 stable COPD patients, with RSV detection associated with higher inflammatory marker levels. Respiratory virus infections are associated with more severe and frequent exacerbations, and may cause chronic infection in COPD. Prevention and early treatment of viral infections may lead to a decreased exacerbation frequency and morbidity associated with COPD
Blue urea : fertilizer with reduced environmental impact
Synthetic nitrogen fertilizers such as urea are a necessity for food production, making them invaluable toward achieving global food security. Conventional manufacture of urea is conducted in centralized production plants at an enormous scale, with the subsequent prilled urea product distributed to the point-of-use. Despite consuming carbon dioxide in the synthesis, the overall process is carbon positive due to the use of fossil feedstocks, resulting in significant net emissions. Blue Urea could be produced using attenuated reaction conditions and hydrogen derived from renewable-powered electrolysis to produce a reduced-carbon alternative. This paper demonstrates the intensified production of urea and ammonium nitrate fertilizers from sustainable feedstocks, namely water, nitrogen, and carbon dioxide. Critically, the process can be scaled-down such that equipment can be housed in a standardized ISO container deployed at the point-of-use, delocalizing production and eliminating costs, and emissions associated with transportation. The urea and ammonium nitrate were synthesized in a semi-continuous process under considerably milder conditions to produce aqueous fertilizers suitable for direct soil application, eliminating the financial and energetic costs associated with drying and prilling. The composition of the fertilizers from this process were found to be free from contaminants, making them ideal for application. In growth studies, the synthesized urea and ammonium nitrate were applied under controlled conditions and found to perform comparably to a commercial fertilizer (Nitram). Crucially, both the synthesized fertilizers enhanced biomass growth, nitrogen uptake and leaf chlorophylls (even in depleted soils), strongly suggesting they would be effective toward improving crop yields and agricultural output. The Blue Urea concept is proposed for installation in ISO containers and deployment on farms, offering a turnkey solution for point-of-need production of nitrogen fertilizers
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