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

    Full text link
    [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

    Full text link
    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

    Get PDF
    This paper reports analysis of the impact of Kenya’s 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

    Full text link
    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, ϕ\phi. 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

    Full text link
    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 (M→0M\to 0), 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 M−1/2M^{-1/2} 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

    Full text link
    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

    Get PDF
    The cultural keystone species (CKS) concept (i.e. ‘species that shape in a major way the cultural identity of a people’ 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 ‘cultural’ AND ‘keystone’ AND ‘species’. Our search was limited to peer‐reviewed 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 cross‐cultural 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 ‘supporting identity’, 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 one‐third of the documents reviewed. To advance biocultural stewardship as a conservation paradigm, we suggest (a) defining CKS as an indissoluble combination of a non‐human 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

    Full text link
    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, P(M)P(\mathcal{M}), of the magnetization transferred across the chain's center. The first two moments of P(M)P(\mathcal{M}) 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

    Full text link
    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 (2.914%±0.016%2.914\%\pm 0.016\% compared to 3.028%±0.023%3.028\%\pm 0.023\%). To investigate damaging, low-probability error sources, we run a distance-25 repetition code and observe a 1.7×10−61.7\times10^{-6} logical error per round floor set by a single high-energy event (1.6×10−71.6\times10^{-7} 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

    Full text link
    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
    • 

    corecore