17,666 research outputs found
Measurement and reporting of climate-smart agriculture: technical guidance for a countrycentric process
Given the extent of climate-smart agriculture (CSA) initiatives at project, national, regional and global levels, there is increasing interest in tracking progress in implementing CSA at national level. CSA is also expected to contribute to higher-level goals (e.g., the Paris Agreement, Africa Union’s Vision 25x25, and the Sustainable Development Goals [SDGs], etc.). Measurement and reporting of climate-smart agriculture (MR of CSA) provides intelligence on necessary the status, effectiveness, efficiency and impacts of interventions, which is critical for meeting stakeholders’ diverse management and reporting needs. In this paper, we build the case for a stakeholder-driven, country-centric framework for MR of CSA, which aims to increase coordination and coherence across stakeholders’ MR activities, while also aligning national reporting with reporting on international commitments. We present practical guidance on how to develop an integrated MR framework, drawing on findings from a multi-country assessment of needs, opportunities and capacities for national MR of CSA. The content of a unified MR framework is determined by stakeholders’ activities (how they promote CSA), needs (why MR is useful to them) and current capacities to conduct periodic monitoring, evaluation and reporting (how ready are institutions, staff and finances). Our analysis found that explicit demand for integration of data systems and active engagement of stakeholders throughout the entire process are key ingredients for building a MR system that is relevant, useful and acted upon. Based on these lessons, we identify a seven-step framework for stakeholders to develop a comprehensive information system for MR of progress in implementing CSA
Policies and Programs Affecting the Employment of People with Disabilities - Policy Brief
The purpose of this brief is to summarize the wide range of federal programs and government policies that influence the employment and program participation decisions of people with disabilities and current research initiatives related to these programs and policies. The brief is organized by the following types of programs, policies, and initiatives: • federal programs that provide cash assistance, in-kind transfers (e.g., health insurance) and education, training, and rehabilitation support based on disability status and/or other characteristics (e.g., family structure); • federal tax policies that provide credits either directly to individuals with disabilities or to employers as an incentive to hire a person with a disability; • other employment-related programs and public policies that provide accommodation support and work incentives for people with disabilities; • recent policy changes that affect people with disabilities; and • some of the current research initiatives related to federal programs, tax policies, other employment programs and policies, and recent policy changes. We conclude with a summary of our program, policy, and research scan. This publication is based on The Economics of Policies and Programs Affecting the Employment of People with Disabilities, which provides a more comprehensive review of the policies and programs discussed here (as well as others) and analyzes the employment effects of these policies and programs within an economic framework
Rod-coil copolymer structures - scaling and field theory
Skalenargumente werden verwendet, um Rod-Coil Copolymere mit fester Zusammensetzung von steifen Stäbchen und flexiblen Ketten zu studieren. In einem selektiven Lösungsmittel, in dem sich nur die Ketten lösen, bildet ein Rod-Coil Multiblock zylinderförmige Micellen aus aggregierten Stäbchen verbunden durch Kettenstücke. Die Stäbchen aggregieren, um Energie zu gewinnen. Dieser Prozeß wird durch den Entropieverlust der flexiblen Ketten ausgeglichen. Das Adsorptionsverhalten von Aggregaten aus parallel aneinandergelagerten, einzelnen Rod-Coil Diblöcken in selektivem Lösungsmittel wird anhand von erweiterten Skalenbetrachtungen diskutiert. Wenn ein solches Aggregat mit den Stäbchen parallel zur Oberfläche adsorbiert, verschieben sich die Stäbchen gegeneinander. Zusätzlich werden die Stabilität der adsorbierten Aggregate und andere mögliche Konfigurationen untersucht. Um einen Rod-Coil Multiblock mit variabler Zusammensetzung zu studieren, wird eine Feldtheorie entwickelt. Jedes Segment kann entweder steif oder flexibel sein. Das System zeigt drei Phasenzustände, offene Kette, amorphe Globule und flüssig-kristalline Globule. Beim Übergang von amorpher zu flüssig-kristalliner Globule steigt der Anteil an steifen Segmenten rapide an. Dieser Übergang wird durch die isotrope Wechselwirkung zwischen den steifen Segmenten und die anisotrope Oberflächenenergie der Globule verursacht. -------------------------------------------------------------------------------- Inhaltszusammenfassung in (englisch) Scaling arguments are used to study rod-coil copolymers with a fixed composition of stiff rods and flexible chains. A rod-coil multiblock immersed in a solvent selective for the chains forms cylindrical micelles of aggregated rods connected by flexible chains. The rods aggregate in order to lower the energy. This process is counterbalanced by the loss of entropy of the chains. The adsorption behaviour of an aggregate of parallel aligned individual rod-coil diblocks in selective solvent is discussed by means of extended scaling methods. If an aggregate of these copolymers adsorbs with the rods parallel to the surface, the rods shift with respect to each other. The stability of an adsorbed aggregate and other possible configurations are discussed. A field theory is constructed to study a rod-coil multiblock with variable composition. Each segment can adopt one of two states, stiff or flexible. The system shows three phase states, open chain, amorphous globule and nematic liquid-crystalline globule. The crossover transition from amorphous to liquid-crystalline globule coincides with a rapid increase in the fraction of stiff segments. This transition is driven by the isotropic interaction between stiff segments and the anisotropy of the globule surface energy
Evolutionary games in the multiverse
Evolutionary game dynamics of two players with two strategies has been
studied in great detail. These games have been used to model many biologically
relevant scenarios, ranging from social dilemmas in mammals to microbial
diversity. Some of these games may in fact take place between a number of
individuals and not just between two. Here, we address one-shot games with
multiple players. As long as we have only two strategies, many results from two
player games can be generalized to multiple players. For games with multiple
players and more than two strategies, we show that statements derived for
pairwise interactions do no longer hold. For two player games with any number
of strategies there can be at most one isolated internal equilibrium. For any
number of players with any number of strategies n, there can
be at most (d-1)^(n-1) isolated internal equilibria. Multiplayer games show a
great dynamical complexity that cannot be captured based on pairwise
interactions. Our results hold for any game and can easily be applied for
specific cases, e.g. public goods games or multiplayer stag hunts
Laser induced magnetization switching in films with perpendicular anisotropy: a comparison between measurements and a multi-macrospin model
Thermally-assisted ultra-fast magnetization reversal in a DC magnetic field
for magnetic multilayer thin films with perpendicular anisotropy has been
investigated in the time domain using femtosecond laser heating. The experiment
is set-up as an optically pumped stroboscopic Time Resolved Magneto-Optical
Kerr Effect magnetometer. It is observed that a modest laser fluence of about
0.3 mJ/square-cm induces switching of the magnetization in an applied field
much less than the DC coercivity (0.8 T) on the sub-nanosecond time-scale. This
switching was thermally-assisted by the energy from the femtosecond pump-pulse.
The experimental results are compared with a model based on the Landau
Lifschitz Bloch equation. The comparison supports a description of the reversal
process as an ultra-fast demagnetization and partial recovery followed by
slower thermally activated switching due to the spin system remaining at an
elevated temperature after the heating pulse.Comment: 8 pages, 10 figures, to be submitted to PR
Aggregates of rod-coil diblock copolymers adsorbed at a surface
The behaviour of rod-coil diblock copolymers close to a surface is discussed
by using extended scaling methods. The copolymers are immersed in selective
solvent such that the rods are likely to aggregate to gain energy. The rods are
assumed to align only parallel to each other, such that they gain a maximum
energy by forming liquid crystalline structures. If an aggregate of these
copolymers adsorbs with the rods parallel to the surface the rods shift with
respect to each other to allow for the chains to gain entropy. It is shown that
this shift decays with increasing distance from the surface. The profile of
this decay away from the surface is calculated by minimisation of the total
free energy of the system. The stability of such an adsorbed aggregate and
other possible configurations are discussed as well.Comment: 10 pages, 11 figure
Aerothermal tests of a 12.5 percent cone at Mach 6.7 for various Reynolds numbers, angles of attack and nose shapes
The effects of free-stream unit Reynolds number, angle of attack, and nose shape on the aerothermal environment of a 3-ft basediameter, 12.5 deg half-angle cone were investigated in the Langley 8-foot high temperature tunnel at Mach 6.7. The average total temperature was 3300 R, the freestream unit Reynolds number ranged from 400,000 to 1,400,000 per foot, and the angle of attack ranged from 0 deg to 10 deg. Three nose configurations were tested on the cone: a 3-in-radius tip, a 1-in-radius tip on an ogive frustum, and a sharp tip on an ogive frustum. Surface-pressure and cold-wall heating-rate distributions were obtained for laminar, transitional temperature in the shock layer were obtained. The location of the start of transition moved forward both on windward and leeward sides with increasing free-stream Reynolds numbers, increasing angle of attack, and decreasing nose bluntness
X-ray and Radio Monitoring of GX 339-4 and Cyg X-1
Previous work by Motch et al. (1985) suggested that in the low/hard state of
GX339-4, the soft X-ray power-law extrapolated backward in energy agrees with
the IR flux level. Corbel and Fender (2002) later showed that the typical hard
state radio power-law extrapolated forward in energy meets the backward
extrapolated X-ray power-law at an IR spectral break, which was explicitly
observed twice in GX339-4. This has been cited as further evidence that jet
synchrotron radiation might make a significant contribution to the observed
X-rays in the hard state. We explore this hypothesis with a series of
simultaneous radio/X-ray hard state observations of GX339-4. We fit these
spectra with a simple, but remarkably successful, doubly broken power-law model
that indeed requires a spectral break in the IR. For most of these
observations, the break position as a function of X-ray flux agrees with the
jet model predictions. We then examine the radio flux/X-ray flux correlation in
Cyg X-1 through the use of 15 GHz radio data, obtained with the Ryle radio
telescope, and Rossi X-ray Timing Explorer data, from the All Sky Monitor and
pointed observations. We find evidence of `parallel tracks' in the radio/X-ray
correlation which are associated with `failed transitions' to, or the beginning
of a transition to, the soft state. We also find that for Cyg X-1 the radio
flux is more fundamentally correlated with the hard, rather than the soft,
X-ray flux.Comment: To Appear in the Proceedings of "From X-ray Binaries to Quasars:
Black Hole Accretion on All Mass Scales" (Amsterdam, July 2004). Eds. T
Maccarone, R. Fender, L. H
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