Are You Tampering With My Data?

We propose a novel approach towards adversarial attacks on neural networks (NN), focusing on tampering the data used for training instead of generating attacks on trained models. Our network-agnostic method creates a backdoor during training which can be exploited at test time to force a neural network to exhibit abnormal behaviour. We demonstrate on two widely used datasets (CIFAR-10 and SVHN) that a universal modification of just one pixel per image for all the images of a class in the training set is enough to corrupt the training procedure of several state-of-the-art deep neural networks causing the networks to misclassify any images to which the modification is applied. Our aim is to bring to the attention of the machine learning community, the possibility that even learning-based methods that are personally trained on public datasets can be subject to attacks by a skillful adversary.Comment: 18 page

Increasing stability for the inverse problem for the Schr\"odinger equation

In this article, we study the increasing stability property for the determination of the potential in the Schr\"odinger equation from partial data. We shall assume that the inaccessible part of the boundary is flat and homogeneous boundary condition is prescribed on this part. In contrast to earlier works, we are able to deal with the case when potentials have some Sobolev regularity and also need not be compactly supported inside the domain

Safe start at home : what parents of newborns need after early discharge from hospital - a focus group study

The length of postpartum hospital stay is decreasing internationally. Earlier hospital discharge of mothers and newborns decreases postnatal care or transfers it to the outpatient setting. This study aimed to investigate the experiences of new parents and examine their views on care following early hospital discharge.; Six focus group discussions with new parents (n = 24) were conducted. A stratified sampling scheme of German and Turkish-speaking groups was employed. A 'playful design' method was used to facilitate participants communication wherein they used blocks and figurines to visualize their perspectives on care models The visualized constructions of care models were photographed and discussions were audio-recorded and transcribed verbatim. Text and visual data was thematically analyzed by a multi-professional group and findings were validated by the focus group participants.; Following discharge, mothers reported feeling physically strained during recuperating from birth and initiating breastfeeding. The combined requirements of infant and self-care needs resulted in a significant need for practical and medical support. Families reported challenges in accessing postnatal care services and lacking inter-professional coordination. The visualized models of ideal care comprised access to a package of postnatal care including monitoring, treating and caring for the health of the mother and newborn. This included home visits from qualified midwives, access to a 24-h helpline, and domestic support for household tasks. Participants suggested that improving inter-professional networks, implementing supervisors or a centralized coordinating center could help to remedy the current fragmented care.; After hospital discharge, new parents need practical support, monitoring and care. Such support is important for the health and wellbeing of the mother and child. Integrated care services including professional home visits and a 24-hour help line may help meet the needs of new families

Perinatal mental disorders in Switzerland : prevalence estimates and use of mental-health services

Background: Perinatal mental disorders (PMDs) are the most common complication of pregnancy and the first postpartum year. Since PMD prevalence and use of mental-health services by perinatal women in Switzerland are unknown, we analysed existing health statistics. Methods: We used statistics from a large health insurance company, hospitals and freelance midwives. We assessed the annual rates of mental healthcare use in perinatal women (n = 13 969). We ascertained the annual rates of PMD treatment in obstetric inpatients (n = 89 699), and annual rates of PMD records by freelance midwives (n = 57 951). In 15 104 women who gave birth in 2012 or 2013, we assessed use of mental-healthcare before and during pregnancy, and in the postpartum year. For the same sample, we determined proportions of medication and consultation treatments. We used multiple regression analysis to estimate the influence of PMD on overall healthcare costs of mandatory health insurance. Results: The annual rate of mental-healthcare use by perinatal women was 16.7%. The annual rate of PMD treatment in obstetric inpatients was 1.1%. The annual rate of PMD records in the midwifery care setting was 2.9%. Women with PMD use mental health services mainly in non-obstetric outpatient settings. Medication was the most frequent treatment. Primary care providers and mental health specialists contributed almost equally to consultation treatments. PMD during pregnancy raised overall costs of healthcare in the postpartum year by 1214 Swiss francs. Conclusions: Health-system research and perinatal healthcare should take into consideration the high prevalence of PMD. Real PMD prevalence may be even higher than our data suggest and could be assessed with a survey using our model of PMD prevalence

Theoretical models of planetary system formation. II. Post-formation evolution

We extend the results of planetary formation synthesis by computing the long-term evolution of synthetic systems from the clearing of the gas disk into the dynamical evolution phase. We use the symplectic integrator SyMBA to numerically integrate the orbits of planets for 100 Ma, using populations from previous studies as initial conditions.We show that within the populations studied, mass and semi-major axis distributions experience only minor changes from post-formation evolution. We also show that, depending upon their initial distribution, planetary eccentricities can statistically increase or decrease as a result of gravitational interactions. We find that planetary masses and orbital spacings provided by planet formation models do not result in eccentricity distributions comparable to observed exoplanet eccentricities, requiring other phenomena such as e.g. stellar fly-bys to account for observed eccentricities

Theoretical models of planetary system formation: mass vs semi-major axis

Planet formation models have been developed during the last years in order to try to reproduce the observations of both the solar system, and the extrasolar planets. Some of these models have partially succeeded, focussing however on massive planets, and for the sake of simplicity excluding planets belonging to planetary systems. However, more and more planets are now found in planetary systems. This tendency, which is a result of both radial velocity, transit and direct imaging surveys, seems to be even more pronounced for low mass planets. These new observations require the improvement of planet formation models, including new physics, and considering the formation of systems. In a recent series of papers, we have presented some improvements in the physics of our models, focussing in particular on the internal structure of forming planets, and on the computation of the excitation state of planetesimals, and their resulting accretion rate. In this paper, we focus on the concurrent effect of the formation of more than one planet in the same protoplanetary disc, and show the effect, in terms of global architecture and composition of this multiplicity. We use a N-body calculation including collision detection to compute the orbital evolution of a planetary system. Moreover, we describe the effect of competition for accretion of gas and solids, as well as the effect of gravitational interactions between planets. We show that the masses and semi-major axis of planets are modified by both the effect of competition and gravitational interactions. We also present the effect of the assumed number of forming planets in the same system (a free parameter of the model), as well as the effect of the inclination and eccentricity damping.Comment: accepted in Astronomy and Astrophysic

On the isomorphism problem of concept algebras

Weakly dicomplemented lattices are bounded lattices equipped with two unary operations to encode a negation on {\it concepts}. They have been introduced to capture the equational theory of concept algebras \cite{Wi00}. They generalize Boolean algebras. Concept algebras are concept lattices, thus complete lattices, with a weak negation and a weak opposition. A special case of the representation problem for weakly dicomplemented lattices, posed in \cite{Kw04}, is whether complete {\wdl}s are isomorphic to concept algebras. In this contribution we give a negative answer to this question (Theorem \ref{T:main}). We also provide a new proof of a well known result due to M.H. Stone \cite{St36}, saying that {\em each Boolean algebra is a field of sets} (Corollary \ref{C:Stone}). Before these, we prove that the boundedness condition on the initial definition of {\wdl}s (Definition \ref{D:wdl}) is superfluous (Theorem \ref{T:wcl}, see also \cite{Kw09}).Comment: 15 page

A Logic of Blockchain Updates

Blockchains are distributed data structures that are used to achieve consensus in systems for cryptocurrencies (like Bitcoin) or smart contracts (like Ethereum). Although blockchains gained a lot of popularity recently, there is no logic-based model for blockchains available. We introduce BCL, a dynamic logic to reason about blockchain updates, and show that BCL is sound and complete with respect to a simple blockchain model

Network based scoring models to improve credit risk management in peer to peer lending platforms

Financial intermediation has changed extensively over the course of the last two decades. One of the most significant change has been the emergence of FinTech. In the context of credit services, fintech peer to peer lenders have introduced many opportunities, among which improved speed, better customer experience, and reduced costs. However, peer-to-peer lending platforms lead to higher risks, among which higher credit risk: not owned by the lenders, and systemic risks: due to the high interconnectedness among borrowers generated by the platform. This calls for new and more accurate credit risk models to protect consumers and preserve financial stability. In this paper we propose to enhance credit risk accuracy of peer-to-peer platforms by leveraging topological information embedded into similarity networks, derived from borrowers' financial information. Topological coefficients describing borrowers' importance and community structures are employed as additional explanatory variables, leading to an improved predictive performance of credit scoring models

Midwives’ engagement in smoking- and alcohol-prevention in prenatal care before and after the introduction of practice guidelines in Switzerland : comparison of survey findings from 2008 and 2018

Background: Evidence suggests that cigarette smoking and alcohol consumption during pregnancy negatively impacts fetal health. Health agencies across countries have developed specific guidelines for health professionals in perinatal care to strengthen their role in smoking and alcohol use prevention. One such example is the “Guideline on Screening and Counselling for prevention of cigarette smoking and alcohol consumption before, during, and after pregnancy” introduced by the Swiss Midwives Association in 2011. The current study assesses the changes in midwives’ engagement in smoking and alcohol use prevention before (2008) and after the introduction of the Guideline (2018). Further, the current study examines differences across regions (German vs. French speaking regions), graduation years (before and after the introduction of the Guideline) and different work settings (hospital vs. self-employed). Methods: Survey data were collected in 2008 (n = 366) and in 2018 (n = 459). Differences in how midwives engaged in smoking and alcohol use prevention between 2008 and 2018 were assessed with chi-square tests, as were differences across German and French speaking regions, graduation years (before and after the introduction of the Guideline) and across different work settings (working in hospitals or as self-employed). Results: An increase in midwives’ awareness of the risks of consuming even small quantities of cigarettes and alcohol for the unborn child between 2008 and 2018 is evident. Explaining the risks to pregnant women who smoke or use alcohol remained the most frequently reported prevention strategy. However, engagement with more extensive smoking and alcohol use preventive strategies across the whole course of pregnancy, such as assisting women in the elaboration of a plan to stop smoking/alcohol use, remained limited. Conclusions: Seven years after its introduction, the effectiveness of the Guideline in increasing midwives’ engagement in smoking and alcohol use prevention appears limited despite midwives’ increased awareness