60 research outputs found
Analytical framework for evaluating the productive impact of cash transfer programmes on household behaviour: Methodological guidelines for the from protection to production project
[Introduction ...] The purpose of this paper is to describe the methodology that will be used for the household-level analysis of economic and productive impacts under the PtoP project. We will first review the conceptual framework underlying our analysis, then delve into the analytical framework, with detailed sections on the methods we may use in the different contexts of each impact evaluation: difference in difference estimators, propensity score matching and regression discontinuity design. This is followed by a discussion of the specific evaluation design of each of the seven countries participating in the project
Onsager coefficients of a Brownian Carnot cycle
We study a Brownian Carnot cycle introduced by T. Schmiedl and U. Seifert
[Europhys. Lett. \textbf{81}, 20003 (2008)] from a viewpoint of the linear
irreversible thermodynamics. By considering the entropy production rate of this
cycle, we can determine thermodynamic forces and fluxes of the cycle and
calculate the Onsager coefficients for general protocols, that is, arbitrary
schedules to change the potential confining the Brownian particle. We show that
these Onsager coefficients contain the information of the protocol shape and
they satisfy the tight-coupling condition irrespective of whatever protocol
shape we choose. These properties may give an explanation why the
Curzon-Ahlborn efficiency often appears in the finite-time heat engines
Cash Transfer Programme, Productive Activities and Labour Supply: Evidence from a Randomised Experiment in Kenya
This paper reports analysis of the impact of Kenyaâs Cash Transfer for Orphans and Vulnerable Children Programme on the household decisions on productive activities using data from a randomized experimental design. Results show that the programme had a positive and significant impact on food consumption coming from home production, accumulation of productive assets, especially on the ownership of small livestock and on formation of nonfarm enterprise, especially for females. The programme has provided more flexibility to families in terms of labour allocation decisions, particularly for those who are geographically isolated. The programme was also found to have reduced child labour, an important objective of the programme. However we find very little impact of the programme on direct indicators of crop production
Thermally induced directed currents in hard rod systems
We study the non equilibrium statistical properties of a one dimensional
hard-rod fluid undergoing collisions and subject to a spatially non uniform
Gaussian heat-bath and periodic potential. The system is able to sustain finite
currents when the spatially inhomogeneous heat-bath and the periodic potential
profile display an appropriate relative phase shift, . By comparison with
the collisionless limit, we determine the conditions for the most efficient
transport among inelastic, elastic and non interacting rods. We show that the
situation is complex as, depending on shape of the temperature profile, the
current of one system may outperform the others.Comment: 5 pages, 2 figure
Inertial effects in B{\"u}ttiker-Landauer Motor and Refrigerator at the Overdamped Limit
We investigate the energetics of a Brownian motor driven by position
dependent temperature, commonly known as the B{\"u}ttiker-Landauer motor.
Overdamped models (M=0) predict that the motor can attain Carnot efficiency.
However, the overdamped limit (), contradicts the previous prediction
due to the kinetic energy contribution to the heat transfer. Using molecular
dynamics simulation and numerical solution of the inertial Langevin equation,
we confirm that the motor can never achieve Carnot efficiency and verify that
the heat flow via kinetic energy diverges as in the overdamped
limit. The reciprocal process of the motor, namely the B{\"u}ttiker-Landauer
refrigerator is also examined. In this case, the overdamped approach succeeds
in predicting the heat transfer only when there is no temperature gradient. Its
found that the Onsager symmetry between the motor and refrigerator does not
suffer from the singular behavior of the kinetic energy contribution.Comment: 12 pages, 10 figure
Comparative effects of tobacco smoking and nasal nicotine
AbstractPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42032/1/228-58-5-309_s00228-002-0481-2.pd
Cultural keystone species as a tool for biocultural stewardship. A global review
The cultural keystone species (CKS) concept (i.e. âspecies that shape in a major way the cultural identity of a peopleâ as defined by Garibaldi and Turner in 2004) has been proposed as part of a common framing for the multiple entangled relationships between species and the socioecological systems in which they exist. However, the blurred and prolific definitions of CKS hamper its univocal application. This work examines the current use of the term CKS to reconcile a definition and explore its practical applications for biocultural stewardship.
We ran a search for the words âculturalâ AND âkeystoneâ AND âspeciesâ. Our search was limited to peerâreviewed articles published in English between 1994 and 2022 (inclusive) and was conducted using Google Scholar, PubMed, Scopus and Web of Science. We extracted and analysed bibliometric information as well as information on (i) the CKS components, (ii) humans' support for CKS and (iii) the definitions of CKS.
From the 313 selected documents, the CKS concept appears to be increasingly accepted, as evidenced by a growing corpus of literature. However, the absence of a systematic and precise way of documenting CKS precludes global crossâcultural comparisons.
The geographical distribution of authors using the concept is biased. We found that 47% of all the CKS reported and 38% of the works identified in our review were located in North America.
Beyond âsupporting identityâ, several other of nature's contributions to people are associated with the CKS definitions. However, the contributions of the sociocultural group to the survival and conservation of the CKS (i.e. stewardship) are made explicit only in oneâthird of the documents reviewed.
To advance biocultural stewardship as a conservation paradigm, we suggest (a) defining CKS as an indissoluble combination of a nonâhuman species and one or more sociocultural groups; (b) acknowledging that species and sociocultural group relations should be classified in a continuum, according to gradients of relationship intensity; and (c) explicitly acknowledging the reciprocal relationships between sociocultural groups and species.
Read the free Plain Language Summary for this article on the Journal blog
Dynamics of magnetization at infinite temperature in a Heisenberg spin chain
Understanding universal aspects of quantum dynamics is an unresolved problem
in statistical mechanics. In particular, the spin dynamics of the 1D Heisenberg
model were conjectured to belong to the Kardar-Parisi-Zhang (KPZ) universality
class based on the scaling of the infinite-temperature spin-spin correlation
function. In a chain of 46 superconducting qubits, we study the probability
distribution, , of the magnetization transferred across the
chain's center. The first two moments of show superdiffusive
behavior, a hallmark of KPZ universality. However, the third and fourth moments
rule out the KPZ conjecture and allow for evaluating other theories. Our
results highlight the importance of studying higher moments in determining
dynamic universality classes and provide key insights into universal behavior
in quantum systems
Suppressing quantum errors by scaling a surface code logical qubit
Practical quantum computing will require error rates that are well below what
is achievable with physical qubits. Quantum error correction offers a path to
algorithmically-relevant error rates by encoding logical qubits within many
physical qubits, where increasing the number of physical qubits enhances
protection against physical errors. However, introducing more qubits also
increases the number of error sources, so the density of errors must be
sufficiently low in order for logical performance to improve with increasing
code size. Here, we report the measurement of logical qubit performance scaling
across multiple code sizes, and demonstrate that our system of superconducting
qubits has sufficient performance to overcome the additional errors from
increasing qubit number. We find our distance-5 surface code logical qubit
modestly outperforms an ensemble of distance-3 logical qubits on average, both
in terms of logical error probability over 25 cycles and logical error per
cycle ( compared to ). To investigate
damaging, low-probability error sources, we run a distance-25 repetition code
and observe a logical error per round floor set by a single
high-energy event ( when excluding this event). We are able
to accurately model our experiment, and from this model we can extract error
budgets that highlight the biggest challenges for future systems. These results
mark the first experimental demonstration where quantum error correction begins
to improve performance with increasing qubit number, illuminating the path to
reaching the logical error rates required for computation.Comment: Main text: 6 pages, 4 figures. v2: Update author list, references,
Fig. S12, Table I
Measurement-induced entanglement and teleportation on a noisy quantum processor
Measurement has a special role in quantum theory: by collapsing the
wavefunction it can enable phenomena such as teleportation and thereby alter
the "arrow of time" that constrains unitary evolution. When integrated in
many-body dynamics, measurements can lead to emergent patterns of quantum
information in space-time that go beyond established paradigms for
characterizing phases, either in or out of equilibrium. On present-day NISQ
processors, the experimental realization of this physics is challenging due to
noise, hardware limitations, and the stochastic nature of quantum measurement.
Here we address each of these experimental challenges and investigate
measurement-induced quantum information phases on up to 70 superconducting
qubits. By leveraging the interchangeability of space and time, we use a
duality mapping, to avoid mid-circuit measurement and access different
manifestations of the underlying phases -- from entanglement scaling to
measurement-induced teleportation -- in a unified way. We obtain finite-size
signatures of a phase transition with a decoding protocol that correlates the
experimental measurement record with classical simulation data. The phases
display sharply different sensitivity to noise, which we exploit to turn an
inherent hardware limitation into a useful diagnostic. Our work demonstrates an
approach to realize measurement-induced physics at scales that are at the
limits of current NISQ processors
- âŠ