88 research outputs found
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Nano-pump based on exothermic surface reactions.
We present simulations indicating that it should be possible to construct a switchable nano-scale fluid pump, driven by exothermic surface reactions. Such a pump could, for instance, be controlled electro-chemically. In our simulations we explore a simple illustration of such a pump. We argue that the simplicity of the pump design could make it attractive for micro/nano-fluidics applications.EU Horizon 2020 program through 766972-FET-OPEN-NANOPHLOW
Reactive Momentum Transfer Contributes to the Self-Propulsion of Janus Particles
We report simulations of a spherical Janus particle undergoing exothermic surface reactions around one pole only. Our model excludes self-phoretic transport by design. Nevertheless, net motion occurs from direct momentum transfer between solvent and colloid, with speed scaling as the square root of the energy released during the reaction. We find that such propulsion is dominated by the system’s short-time response, when neither the time dependence of the flow around the colloid nor the solvent compressibility can be ignored. Our simulations agree reasonably well with previous experiments.Horizon 2020 FET Ope
Topical: Learning Repository Embeddings from Source Code using Attention
Machine learning on source code (MLOnCode) promises to transform how software
is delivered. By mining the context and relationship between software
artefacts, MLOnCode augments the software developers capabilities with code
auto-generation, code recommendation, code auto-tagging and other data-driven
enhancements. For many of these tasks a script level representation of code is
sufficient, however, in many cases a repository level representation that takes
into account various dependencies and repository structure is imperative, for
example, auto-tagging repositories with topics or auto-documentation of
repository code etc. Existing methods for computing repository level
representations suffer from (a) reliance on natural language documentation of
code (for example, README files) (b) naive aggregation of method/script-level
representation, for example, by concatenation or averaging. This paper
introduces Topical a deep neural network to generate repository level
embeddings of publicly available GitHub code repositories directly from source
code. Topical incorporates an attention mechanism that projects the source
code, the full dependency graph and the script level textual information into a
dense repository-level representation. To compute the repository-level
representations, Topical is trained to predict the topics associated with a
repository, on a dataset of publicly available GitHub repositories that were
crawled along with their ground truth topic tags. Our experiments show that the
embeddings computed by Topical are able to outperform multiple baselines,
including baselines that naively combine the method-level representations
through averaging or concatenation at the task of repository auto-tagging.Comment: Pre-print, under revie
Expressive variational quantum circuits provide inherent privacy in federated learning
Federated learning has emerged as a viable distributed solution to train
machine learning models without the actual need to share data with the central
aggregator. However, standard neural network-based federated learning models
have been shown to be susceptible to data leakage from the gradients shared
with the server. In this work, we introduce federated learning with variational
quantum circuit model built using expressive encoding maps coupled with
overparameterized ans\"atze. We show that expressive maps lead to inherent
privacy against gradient inversion attacks, while overparameterization ensures
model trainability. Our privacy framework centers on the complexity of solving
the system of high-degree multivariate Chebyshev polynomials generated by the
gradients of quantum circuit. We present compelling arguments highlighting the
inherent difficulty in solving these equations, both in exact and approximate
scenarios. Additionally, we delve into machine learning-based attack strategies
and establish a direct connection between overparameterization in the original
federated learning model and underparameterization in the attack model.
Furthermore, we provide numerical scaling arguments showcasing that
underparameterization of the expressive map in the attack model leads to the
loss landscape being swamped with exponentially many spurious local minima
points, thus making it extremely hard to realize a successful attack. This
provides a strong claim, for the first time, that the nature of quantum machine
learning models inherently helps prevent data leakage in federated learning.Comment: 24 pages, 13 figure
Effectiveness of Mechanisms and Models of Coordination between Organizations, Agencies and Bodies Providing or Financing Health Services in Humanitarian Crises: A Systematic Review.
BACKGROUND: Effective coordination between organizations, agencies and bodies providing or financing health services in humanitarian crises is required to ensure efficiency of services, avoid duplication, and improve equity. The objective of this review was to assess how, during and after humanitarian crises, different mechanisms and models of coordination between organizations, agencies and bodies providing or financing health services compare in terms of access to health services and health outcomes. METHODS: We registered a protocol for this review in PROSPERO International prospective register of systematic reviews under number PROSPERO2014:CRD42014009267. Eligible studies included randomized and nonrandomized designs, process evaluations and qualitative methods. We electronically searched Medline, PubMed, EMBASE, Cochrane Central Register of Controlled Trials, CINAHL, PsycINFO, and the WHO Global Health Library and websites of relevant organizations. We followed standard systematic review methodology for the selection, data abstraction, and risk of bias assessment. We assessed the quality of evidence using the GRADE approach. RESULTS: Of 14,309 identified citations from databases and organizations' websites, we identified four eligible studies. Two studies used mixed-methods, one used quantitative methods, and one used qualitative methods. The available evidence suggests that information coordination between bodies providing health services in humanitarian crises settings may be effective in improving health systems inputs. There is additional evidence suggesting that management/directive coordination such as the cluster model may improve health system inputs in addition to access to health services. None of the included studies assessed coordination through common representation and framework coordination. The evidence was judged to be of very low quality. CONCLUSION: This systematic review provides evidence of possible effectiveness of information coordination and management/directive coordination between organizations, agencies and bodies providing or financing health services in humanitarian crises. Our findings can inform the research agenda and highlight the need for improving conduct and reporting of research in this field
Kosso Eloul : Celebration of the Arch
Includes a brief introductory note by Cumming and a statement by Kosso
Culture Change in a Bedouin Tribe: an Ethnographic History of the 'Arab Al-Hjerat, Lower Galilee, Israel Ca. Ad 1790-1977. (Volumes I and II).
The present dissertation describes and analyses the growth of the 'Arab al-Hjerat from a small short-range nomadic bedouin herding camp at the end of the eighteenth century to its 1977 regional prominence. During this period the tribe increased in size from 3-5 nuclear households to over 3,500 members and centralized its leadership while adapting under three successive regimes--Ottoman, British, and Israeli,--to sedentary neighbors and life, market-oriented production, wage labor, and an industrial state economy, with major effects in all aspects of its culture. In accord with the cybernetic perception of culture as an integrated system of material, social, and symbolic elements, an attempt is made to follow the mutually causal inter-relatedness of these changes in reference to events and processes occurring in the regional and state milieus, in order to gain a better general underst and ing of culture change. Several related issues are extensively developed notably: the organization of cultures as viable systems; ethnicity, ethnic boundaries, and the articulation of an ethnic minority in a pluralistic context including state administration; "cultural" versus "power" brokerage; and the rise of patronage in a tribal context.Ph.D.Cultural anthropologyUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/158983/1/8224941.pd
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