Global convergence of quorum-sensing networks

In many natural synchronization phenomena, communication between individual elements occurs not directly, but rather through the environment. One of these instances is bacterial quorum sensing, where bacteria release signaling molecules in the environment which in turn are sensed and used for population coordination. Extending this motivation to a general non- linear dynamical system context, this paper analyzes synchronization phenomena in networks where communication and coupling between nodes are mediated by shared dynamical quan- tities, typically provided by the nodes' environment. Our model includes the case when the dynamics of the shared variables themselves cannot be neglected or indeed play a central part. Applications to examples from systems biology illustrate the approach.Comment: Version 2: minor editions, added section on noise. Number of pages: 36

Symmetries, Stability, and Control in Nonlinear Systems and Networks

This paper discusses the interplay of symmetries and stability in the analysis and control of nonlinear dynamical systems and networks. Specifically, it combines standard results on symmetries and equivariance with recent convergence analysis tools based on nonlinear contraction theory and virtual dynamical systems. This synergy between structural properties (symmetries) and convergence properties (contraction) is illustrated in the contexts of network motifs arising e.g. in genetic networks, of invariance to environmental symmetries, and of imposing different patterns of synchrony in a network.Comment: 16 pages, second versio

Spiritual Activism and Political Solidarity in So Far From God and Mother Tongue: Two Views By Two Authors

SPIRITUAL ACTIVISM AND POLITICAL SOLIDARITY IN SO FAR FROM GOD AND MOTHER TONGUE: TWO VIEWS BY TWO AUTHORS by Jean Paul Russo Florida International University, 2020 Miami, Florida Professor Anne Castro, Major Professor This thesis focuses on the intersection between spirituality and political action in the works of two Latinx authors, Demetria Martinez and Ana Castillo. Building on Gloria Anzaldua’s theories of trauma, narrative, and what she terms ‘conocimiento,’ I contend that the novels So Far From God, and Mother Tongue, present an alternative approach to political action that is derived from a common experience of suffering and trauma as experienced by Latina communities. The political actions in the two novels and the ideas which inspire those actions, are born out of a need for solidarity between individuals, and are founded upon the idea that politics ought to be inspired by the spiritual lives and beliefs of individuals, as it is a central aspect of their identity

A REVIEW OF THE PUBLIC HEALTH AND MENTAL HEALTH ROLES IN RESPONSE TO COMMUNITY DISASTERS AND THE RATIONALE FOR EFFECTIVE INTERDISCIPLINARY COLLABORATIONS

Disasters vary in scope, size, and cause. Relevant public health aspects of disasters include community impact and the response of health professionals to alleviate stress and dangerous conditions surrounding the disaster. Public health focuses on the prevention of disease and the promotion of health. Disaster preparedness and response are significant areas in the field of public health. Disasters pose threats to the general public through increases in injury, death, and changes in infrastructure. The public health response to disaster includes assessments of the community impact, surveillance for disease, addressing sanitary health concerns, and providing information to the public. Mental health professionals also have important roles in responding to disaster in the community. In addition to physical aspects, disasters also may pose psychological risks to individuals and to the effected community. These risks may include stress, anxiety, and depression. Mental health workers provide counseling, support, and education to assist people affected by disaster in returning to their pre-disaster level of functioning. Traditionally there has been a separation between the disciplines of public health and mental health. Public health is population-based and mental health has been traditionally regarded being more individually based. During a disastrous event communication and organization among agencies is critical to an effective response. Increased collaborations between public health and mental health are needed to facilitate an appropriate and effective disaster response. Both areas aim to improve overall health and well being, and therefore are inter-related. Each discipline needs to become more familiar with the nature of each other's work. Overall increases in public and mental health research, planning, training, and education programs are needed to understand and appreciate both the public health and mental health consequences of disaster and to improve community participation and preparedness

Shrinkage Estimators in Online Experiments

We develop and analyze empirical Bayes Stein-type estimators for use in the estimation of causal effects in large-scale online experiments. While online experiments are generally thought to be distinguished by their large sample size, we focus on the multiplicity of treatment groups. The typical analysis practice is to use simple differences-in-means (perhaps with covariate adjustment) as if all treatment arms were independent. In this work we develop consistent, small bias, shrinkage estimators for this setting. In addition to achieving lower mean squared error these estimators retain important frequentist properties such as coverage under most reasonable scenarios. Modern sequential methods of experimentation and optimization such as multi-armed bandit optimization (where treatment allocations adapt over time to prior responses) benefit from the use of our shrinkage estimators. Exploration under empirical Bayes focuses more efficiently on near-optimal arms, improving the resulting decisions made under uncertainty. We demonstrate these properties by examining seventeen large-scale experiments conducted on Facebook from April to June 2017

Synchronization and Redundancy: Implications for Robustness of Neural Learning and Decision Making

Learning and decision making in the brain are key processes critical to survival, and yet are processes implemented by non-ideal biological building blocks which can impose significant error. We explore quantitatively how the brain might cope with this inherent source of error by taking advantage of two ubiquitous mechanisms, redundancy and synchronization. In particular we consider a neural process whose goal is to learn a decision function by implementing a nonlinear gradient dynamics. The dynamics, however, are assumed to be corrupted by perturbations modeling the error which might be incurred due to limitations of the biology, intrinsic neuronal noise, and imperfect measurements. We show that error, and the associated uncertainty surrounding a learned solution, can be controlled in large part by trading off synchronization strength among multiple redundant neural systems against the noise amplitude. The impact of the coupling between such redundant systems is quantified by the spectrum of the network Laplacian, and we discuss the role of network topology in synchronization and in reducing the effect of noise. A range of situations in which the mechanisms we model arise in brain science are discussed, and we draw attention to experimental evidence suggesting that cortical circuits capable of implementing the computations of interest here can be found on several scales. Finally, simulations comparing theoretical bounds to the relevant empirical quantities show that the theoretical estimates we derive can be tight.Comment: Preprint, accepted for publication in Neural Computatio

Context matters (but how and why?) A hypothesis-led literature review of performance based financing in fragile and conflict-affected health systems

** From PLOS via Jisc Publications Router. ** History: received 11-07-2017; collection 2018; accepted 20-03-2018; epub 03-04-2018. ** Licence for this article: http://creativecommons.org/licenses/by/4.0/Performance-based financing (PBF) schemes have been expanding rapidly across low and middle income countries in the past decade, with considerable external financing from multilateral, bilateral and global health initiatives. Many of these countries have been fragile and conflict-affected (FCAS), but while the influence of context is acknowledged to be important to the operation of PBF, there has been little examination of how it affects adoption and implementation of PBF. This article lays out initial hypotheses about how FCAS contexts may influence the adoption, adaption, implementation and health system effects of PBF. These are then interrogated through a review of available grey and published literature (140 documents in total, covering 23 PBF schemes). We find that PBF has been more common in FCAS contexts, which were also more commonly early adopters. Very little explanation of the rationale for its adoption, in particular in relation with the contextual features, is given in programme documents. However, there are a number of factors which could explain this, including the greater role of external actors and donors, a greater openness to institutional reform, and lower levels of trust within the public system and between government and donors, all of which favour more contractual approaches. These suggest that rather than emerging despite fragility, conditions of fragility may favour the rapid emergence of PBF. We also document few emerging adaptations of PBF to humanitarian settings and limited evidence of health system effects which may be contextually driven, but these require more in-depth analysis. Another area meriting more study is the political economy of PBF and its diffusion across contexts.sch_iih13pub5303pub4 [e0195301

Higher Grading Generalisations of the Toda Systems

In the present paper we obtain some integrable generalisations of the Toda system generated by flat connection forms taking values in higher ${\bf Z}$--grading subspaces of a simple Lie algebra, and construct their general solutions. One may think of our systems as describing some new fields of the matter type coupled to the standard Toda systems. This is of special interest in nonabelian Toda theories where the latter involve black hole target space metrics. We also give a derivation of our conformal system on the base of the Hamiltonian reduction of the WZNW model; and discuss a relation between abelian and nonabelian systems generated by a gauge transformation that maps the first grading description to the second. The latter involves grades larger than one.Comment: 24 pages, latex, no figures; Expanded version accepted for publication in Nuclear Physics

Branching projections of ventrolateral reticular neurons to the medial preoptic area and lumbo-sacral spinal cord

Different findings indicate that rostral ventrolateral reticular nucleus (RVL) is neuronal substrate of integration and regulation of the cardiovascular functions. Some efferent RVL neurons project to the thoraco-lumbar spinal cord and excite preganglionic sympathetic neurons, to the spinal phrenic motor neurons involved in inspiratory function and increase the activity of vasoconstrictor fibres innervating blood vessels in the skin and skeletal muscle. Our study was aimed at revealing presence of neurons within RVL supplying branching collateral input to the medial preoptic area (MPA) and to the lumbo-sacral spinal cord (SC-L) in the rat. All animal experiments were carried out in accordance with current institutional guidelines for the care and use of experimental animals. We have employed double fluorescent-labelling procedure: the projections were defined by injections of two retrograde tracers: Rhodamine Labelled Bead (RBL) and Fluoro Gold (FG) in the MPA and SC-L, respectively. Our results showed the presence of few single FG neurons and single RBL neurons in the RVL. The size of FG-neurons and RBL-neurons was medium (25–30 μm) and large (50 μm). Few double-projecting neurons were distributed in the middle third of RVL nucleus, their size was 30–40 μm. The results demonstrate that pools of neurons in the RVL have collateral projections to the MPA and SC-L and they are involved in ascending and descending pathway. These data suggest that these neurons could play a role in maintaining activity of central and peripheral blood flow