12,913 research outputs found
Differentially private partitioned variational inference
Learning a privacy-preserving model from sensitive data which are distributed
across multiple devices is an increasingly important problem. The problem is
often formulated in the federated learning context, with the aim of learning a
single global model while keeping the data distributed. Moreover, Bayesian
learning is a popular approach for modelling, since it naturally supports
reliable uncertainty estimates. However, Bayesian learning is generally
intractable even with centralised non-private data and so approximation
techniques such as variational inference are a necessity. Variational inference
has recently been extended to the non-private federated learning setting via
the partitioned variational inference algorithm. For privacy protection, the
current gold standard is called differential privacy. Differential privacy
guarantees privacy in a strong, mathematically clearly defined sense.
In this paper, we present differentially private partitioned variational
inference, the first general framework for learning a variational approximation
to a Bayesian posterior distribution in the federated learning setting while
minimising the number of communication rounds and providing differential
privacy guarantees for data subjects.
We propose three alternative implementations in the general framework, one
based on perturbing local optimisation runs done by individual parties, and two
based on perturbing updates to the global model (one using a version of
federated averaging, the second one adding virtual parties to the protocol),
and compare their properties both theoretically and empirically.Comment: Published in TMLR 04/2023: https://openreview.net/forum?id=55Bcghgic
Startup Home-Based Social Media Businesses
Purpose: The objective of this study is to investigate and analyze issues faced by small-business owners while running their businesses via social media sites, and to emphasize the opportunities for conducting business via social media.
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Theoretical framework:  Small businesses are vital to the success of any economy, through job creation, sparking innovation, and providing opportunities for many people to achieve financial success and independence. In today’s social media-driven environment, it is essential that small business’ owners engage with social media networking sites and understand how social media can play a crucial role in developing their businesses.
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Design/methodology/approach: The research focuses on analyzing the day-to-day operations and procedures of small businesses involving social media networking sites. Two questionnaires were developed to analyze and investigate these issues effectively.
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Findings: Â The results reveal the importance of organizing the operations and procedures of social media businesses, also emphasize the opportunities for conducting business via social media sites.
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Research, Practical & Social implications: Â this study was conducted to help business owners to engage with social media sites, as well as to solve issues that they face while running their online businesses.
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Originality/value: The results of the first questionnaire indicate issues from customers’ perspectives, while the second questionnaire indicate issues from merchants’ perspectives. The results reveal the importance of organizing the operations and procedures of social media businesses, also emphasize the opportunities for conducting business via social media sites
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Food Security Under a Changing Climate: Exploring the Integration of Resilience in Research and Practice
Climate change poses significant risks to our food systems, thus jeopardising the food security of millions of people worldwide. The concept of resilience is increasingly being proposed as a framework to find solutions to these challenges. In this chapter, we assess how resilience has been integrated in discussions about climate change and food security by both academics and practitioners. We performed a targeted review of the academic literature on climate change, food security, and resilience and found that despite a growing body of literature on the subject, the pathways through which actions translate into resilience and then into food security remain unclear. An examination of a sample of projects implemented through the Adaptation Fund revealed that many good practices with potential for resilience-building are used but also that suitable indicators and methods to monitor and evaluate resilience and its outcomes are lacking. Based on our findings, we conclude that while the concept of resilience has accompanied and may have favoured a transition towards more integrated approaches and interventions in work related to climate change and food security, further efforts are needed to identify an efficient and rational sequence of interventions to improve food security in response to climate threats
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Ensuring Access to Safe and Nutritious Food for All Through the Transformation of Food Systems
Resource-efficient high-dimensional entanglement detection via symmetric projections
We introduce two families of criteria for detecting and quantifying the
entanglement of a bipartite quantum state of arbitrary local dimension. The
first is based on measurements in mutually unbiased bases and the second is
based on equiangular measurements. Both criteria give a qualitative result in
terms of the state's entanglement dimension and a quantitative result in terms
of its fidelity with the maximally entangled state. The criteria are
universally applicable since no assumptions on the state are required.
Moreover, the experimenter can control the trade-off between
resource-efficiency and noise-tolerance by selecting the number of measurements
performed. For paradigmatic noise models, we show that only a small number of
measurements are necessary to achieve nearly-optimal detection in any
dimension. The number of global product projections scales only linearly in the
local dimension, thus paving the way for detection and quantification of very
high-dimensional entanglement.Comment: 6+2 page
Economia colaborativa
A importância de se proceder à análise dos principais desafios jurÃdicos que a economia colaborativa coloca – pelas implicações que as mudanças de paradigma dos modelos de negócios e dos sujeitos envolvidos suscitam − é indiscutÃvel, correspondendo à necessidade de se fomentar a segurança jurÃdica destas práticas, potenciadoras de crescimento económico e bem-estar social.
O Centro de Investigação em Justiça e Governação (JusGov) constituiu uma equipa multidisciplinar que, além de juristas, integra investigadores de outras áreas, como a economia e a gestão, dos vários grupos do JusGov – embora com especial participação dos investigadores que integram o grupo E-TEC (Estado, Empresa e Tecnologia) – e de outras prestigiadas instituições nacionais e internacionais, para desenvolver um projeto neste domÃnio, com o objetivo de identificar os problemas jurÃdicos que a economia colaborativa suscita e avaliar se já existem soluções para aqueles, refletindo igualmente sobre a conveniência de serem introduzidas alterações ou se será mesmo necessário criar nova regulamentação.
O resultado desta investigação é apresentado nesta obra, com o que se pretende fomentar a continuação do debate sobre este tema.Esta obra é financiada por fundos nacionais através da FCT — Fundação para a Ciência e a Tecnologia, I.P., no âmbito do Financiamento UID/05749/202
Victims' Access to Justice in Trinidad and Tobago: An exploratory study of experiences and challenges of accessing criminal justice in a post-colonial society
This thesis investigates victims' access to justice in Trinidad and Tobago, using their own narratives. It seeks to capture how their experiences affected their identities as victims and citizens, alongside their perceptions of legitimacy regarding the criminal justice system. While there have been some reforms in the administration of criminal justice in Trinidad and Tobago, such reforms have not focused on victims' accessibility to the justice system. Using grounded theory methodology, qualitative data was collected through 31 in-depth interviews with victims and victim advocates. The analysis found that victims experienced interpersonal, structural, and systemic barriers at varying levels throughout the criminal justice system, which manifested as institutionalized secondary victimization, silencing and inequality. This thesis argues that such experiences not only served to appropriate conflict but demonstrates that access is often given in a very narrow sense. Furthermore, it shows a failure to encompass access to justice as appropriated conflicts are left to stagnate in the system as there is often very little resolution. Adopting a postcolonial lens to analyse victims' experiences, the analysis identified othering practices that served to institutionalize the vulnerability and powerlessness associated with victim identities. Here, it is argued that these othering practices also affected the rights consciousness of victims, delegitimating their identities as citizens. Moreover, as a result of their experiences, victims had mixed perceptions of the justice system. It is argued that while the system is a legitimate authority victims' endorsement of the system is questionable, therefore victims' experiences suggest that there is a reinforcement of the system's legal hegemony. The findings suggest that within the legal system of Trinidad and Tobago, legacies of colonialism shape the postcolonial present as the psychology and inequalities of the past are present in the interactions and processes of justice. These findings are relevant for policymakers in Trinidad and Tobago and other regions. From this study it is recognized that, to improve access to justice for victims, there needs to be a move towards victim empowerment that promotes resilience and enhances social capital. Going forward it is noted that there is a need for further research
Interval Type-2 Beta Fuzzy Near Sets Approach to Content-Based Image Retrieval
In computer-based search systems, similarity plays a key role in replicating the human search process. Indeed, the human search process underlies many natural abilities such as image recovery, language comprehension, decision making, or pattern recognition. The search for images consists of establishing a correspondence between the available image and that sought by the user, by measuring the similarity between the images. Image search by content is generaly based on the similarity of the visual characteristics of the images. The distance function used to evaluate the similarity between images depends notonly on the criteria of the search but also on the representation of the characteristics of the image. This is the main idea of a content-based image retrieval (CBIR) system. In this article, first, we constructed type-2 beta fuzzy membership of descriptor vectors to help manage inaccuracy and uncertainty of characteristics extracted the feature of images. Subsequently, the retrieved images are ranked according to the novel similarity measure, noted type-2 fuzzy nearness measure (IT2FNM). By analogy to Type-2 Fuzzy Logic and motivated by near sets theory, we advanced a new fuzzy similarity measure (FSM) noted interval type-2 fuzzy nearness measure (IT-2 FNM). Then, we proposed three new IT-2 FSMs and we have provided mathematical justification to demonstrate that the proposed FSMs satisfy proximity properties (i.e. reflexivity, transitivity, symmetry, and overlapping). Experimental results generated using three image databases showing consistent and significant results
Understanding interactions between Ramularia collo-cygni and barley leaf physiology to target improvements in host resistance and disease control strategy
Ramularia Leaf Spot (RLS) is an increasingly problematic disease of barley.
Control options are limited as the causal fungus, Ramularia collo-cygni, has
developed resistance to several of the major fungicide groups. Developing
new methods for controlling this disease is therefore a priority. R. collo-cygni
can grow systemically in barley plants from infected seed, without inducing
visible symptoms. In the field, visible symptoms normally only appear after
flowering. The relative contribution of the latent and symptomatic stages of
the fungal lifecycle to reduction in barley yield is not currently known with any
certainty. Two possibilities are that the effect of asymptomatic infection on
pre-flowering photosynthetic activity, and the development of grain sink
capacity, plays an important role; or that reduction in photosynthetic activity
during grain filling, resulting from lesion development and loss of green leaf
area, is the predominant factor. This research aimed to increase our
understanding of the impact of different phases of the fungal lifecycle on
barley photosynthesis and yield formation, to better target host resistance
and disease control strategies.
Controlled environment and field experiments were used to determine the
relative effects of asymptomatic and symptom-expressing phases of R. collo-cygni infection on photosynthesis and yield formation in spring barley. In
controlled environment experiments leaf photosynthetic activity was
measured in seedlings inoculated with suspensions of R. collo-cygni mycelia.
Measurements were made before and after visible symptom development
using Infra-Red Gas Analysis (IRGA), chlorophyll fluorescence analysis and
chlorophyll fluorescence imaging. No reduction in photosynthetic activity was
observed in leaves infected with R. collo-cygni, compared to those of non-
infected leaves, during the latent phase of infection. After the appearance of
visible symptoms, photosynthetic activity within lesions reduced as the
lesions developed. However, this did not lead to reductions in photosynthetic
activity when measured across the whole leaf area, suggesting that for there
to be a significant effect of disease on whole leaf photosynthetic activity,
visible symptoms must develop into mature lesions and coalesce to cover
larger areas of the leaf surface.
In field experiments plots were treated with a full fungicide regime, left
untreated, or inoculated with R. collo-cygni and treated with fungicide to
which R. collo-cygni is resistant (the latter as a precaution against lack of
natural RLS disease that year and/or other diseases developing on untreated
plots). RLS was the only disease of significance that developed in untreated
or inoculated plots. Symptoms first appeared after flowering, around Zadoks
Growth Stage 72. Fungicide-treated plots remained free of disease.
Chlorophyll fluorescence analysis of field plants showed no effect of infection
on the maximum quantum efficiency of Photosystem II (Fv/Fm) before visible
symptom development, consistent with results from controlled environment
experiments. Grain yield of untreated and fungicide-treated plots was
predicted from fixed common values of radiation use efficiency (RUE) and
utilisation of soluble sugar reserves, and measured values of post-flowering
healthy (green) leaf area light interception. Grain yields predicted from the
difference in post-flowering light interception between fungicide-treated plants
and untreated or inoculated plants displaying symptoms of RLS were
comparable with the measured yield response to fungicide. This suggests
that yield loss to RLS is primarily associated with a reduction in light capture
during grain filling, resulting from lesion development and loss of green leaf
area.
Results from controlled environment and field experiments suggested that
symptom expression was associated with leaf senescence. Further controlled
environment experiments tested this relationship by using treatments to vary
the onset and rate of leaf senescence. Seedlings that were treated with
cytokinin to delay senescence after inoculation with suspensions of R. collo-cygni mycelia developed fewer lesions than control plants. Fungal growth, as
measured by quantification of R. collo-cygni DNA in leaves, was also
restricted in plants treated with cytokinin.
Collectively these results suggest that prevention of visible symptom
development, rather than prevention of asymptomatic growth, is the most
important target for management of this disease. Control methods targeted at
delaying senescence could be a useful avenue for further investigation
The developing maternal-infant relationship: a qualitative longitudinal study
Aim
The study aimed to explore maternal perceptions and the use of knowledge relating to their infant’s mental health over time using qualitative longitudinal research.
Background
There has been a growing interest in infant mental health over recent years. Much of this interest is directed through the lens of infant determinism, through knowledge regarding neurological development resulting in biological determinism. Research and policy in this field are directed toward individual parenting behaviours, usually focused on the mother. Despite this, there is little attention given to maternal perspectives of infant mental health, indicating that a more innovative approach to methodology is required.
Methods
This study took a qualitative longitudinal approach, and interviews were undertaken with seven mothers from the third trimester of pregnancy and then throughout the first year of the infant’s life. Interviews were conducted at 34 weeks of pregnancy, and then when the infant was 6 and 12 weeks, 6, 9, and 12 months, alongside the collection of researcher field notes—a total of 41 interviews. Data were analysed by creating case profiles, memos, and summaries, and then cross-comparison of the emerging narratives. A psycho-socially informed approach was taken to the analysis of data.
Findings
Three interrelated themes emerged from the data: evolving maternal identity, growing a person, and creating a safe space. The theme of evolving maternal identity dominated the other themes of growing a person and creating a safe space in a way that met perceived socio-cultural requirements for mothering and childcare practices. Participants’ personal stories give voice to their perceptions of the developing maternal-infant relationship in the context of their socio-cultural setting, relationships with others, and experiences over time.
Conclusions
This study adds new knowledge by giving mothers a voice to express how the maternal-infant relationship develops over time. The findings demonstrate how the developing maternal-infant relationship grows in response to their mutual needs as the mother works to create and sustain identities for herself and the infant that will fit within their socio-cultural context and individual situations. Additionally, the findings illustrate the importance of temporal considerations, social networks, and intergenerational relationships to this evolving process. Recommendations for practice, policy, and education are made that reflect the unique relationship between mother and infant and the need to conceptualise this using an ecological approach
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