Dynamical epidemic suppression using stochastic prediction and control

We consider the effects of noise on a model of epidemic outbreaks, where the outbreaks appear. randomly. Using a constructive transition approach that predicts large outbreaks, prior to their occurrence, we derive an adaptive control. scheme that prevents large outbreaks from occurring. The theory inapplicable to a wide range of stochastic processes with underlying deterministic structure.Comment: 14 pages, 6 figure

School Segregation, Educational Attainment, and Crime: Evidence from the End of Busing in Charlotte-Mecklenburg

We study the impact of the end of race-based busing in Charlotte-Mecklenburg schools (“CMS”) on academic achievement, educational attainment, and young adult crime. In 2001, CMS was prohibited from using race in assigning students to schools. School boundaries were redrawn dramatically to reflect the surrounding neighborhoods, and half of its students received a new assignment. Using addresses measured prior to the policy change, we compare students in the same neighborhood that lived on opposite sides of a newly drawn boundary. We find that both white and minority students score lower on high school exams when they are assigned to schools with more minority students. We also find decreases in high school graduation and four-year college attendance for whites, and large increases in crime for minority males. The impacts on achievement and attainment are smaller in younger cohorts, while the impact on crime remains large and persistent for at least nine years after the re-zoning. We show that compensatory resource allocation policies in CMS likely played an important role in mitigating the impact of segregation on achievement and attainment, but had no impact on crime. We conclude that the end of busing widened racial inequality, despite efforts by CMS to mitigate the impact of increases in segregation

Cytotoxic T lymphocytes induced against allogeneic I-region determinants react with Ia molecules on trinitrophenyl-conjugated syngeneic target cells

The major histocompatibility complex codes for determinants which are recognized by and serve as targets for cytolytic T lymphocytes (CTL) (1). Antigens coded for by the K and D loci of the H-2 complex can activate xenogeneic or allogeneic CTL (2,3). In addition, the H-2K or H-2D gene products function as those molecules against which syngeneic CTL responses specific for chemical, viral, and minor H antigens are directed (4-8). It has recently been shown that Ia determinants can also serve as target antigens for distinct but weaker CTL responses (9-13). Those clones which recognize Ia antigens see them independently of K- or D- coded antigens as shown in genetic studies and by antisera-blocking experiments (12,13). We have proposed that the existence of clones of CTL specific for I-region-coded determinants is not fortuitous; rather these clones specifically recognize Ia determinants and may have an immunoregulatory role. These CTL may affect those immune functions which are at least partially dependent on or controlled by I-region-coded molecules. Two predictions can be made and tested concerning the role of Ia determinants in cytolytic systems and the role, if any, of I-region- specific CTL in regulating the immune response: (a) that if as we and others have shown, certain Ia specificities can serve as a third series of major histocompatibility antigens, then Ia antigens should be susceptible to the same types of antigenic modifications as H-2K- or H-2D-coded structures and thus serve as targets for CTL directed against modified-self in selected systems; and (b) that allogeneically induced I-region-specific CTL should demonstrate cross-reactivity with targets bearing modified syngeneic I-region-coded determinants. Data will be present which demonstrates that trinitrophenyl (TNP)-modified syngeneic I-region determinants can serve as targets for CTL induced by allogeneic Ia antigens

Cytotoxic T lymphocytes specific for I region determinants do not require interactions with H-2K or D gene products

Gene products coded for by the major hisocompatibility complex (MHC) can serve as target antigens for cytotoxic T lymphocytes (CTL) (1). A variety of test systems are available which have yielded information consistently reinforcing the importance of this complex of genes in the generation and effector phases of the cytotoxic immune response. Originally, it was shown that allogeneically-induced CTL had specificity primarily for the products of the K and D loci of the mouse H-2 complex (2). More recently this has also been found to be the case for xenogeneic immunizations (3,4). Additional examples of T cell-mediated lysis have been reported involving viral-infected or chemically- modified syngeneic stimulating and target cells in which homology at H-2K or H-2D was required between the responding and target cells for appreciable lysis to occur (5-7). Moreover, CTL specific for minor histocompatability antigens are able to lyse only target cells bearing these membrane antigens and sharing a common H-2K or H2-D gene product with the effector (8,9). Two hypotheses have been proposed to explain the requirement for H-2 identity between effector and targets in these systems. CTL may recognize new antigenic determinants created by the interaction of the modifier with syngeneic K and D gene products. Alternately, a dual recognition system my exist, requiring an antigen-specific receptor as well as a second receptor with specificity for homologous H-2K or H-2D determinants (5). Neither model can be excluded at this time. The I region also contains genes coding for histocompatibility loci since animals differing at the I-A or I-C regions of the H-2 complex reject skin grafts (10-12), though less rapidly than mice differing at the H-2K or H-2D regions, Also CTL can be generated to I region determinants but less efficiently than CTL specific for H-2K or H-2D gene products (12-14). The question can therefore be raised, whether the I region minor histocompatibility loci function independently from the H-2K or H-2D loci or whether I region-specific cytolysis requires the participation of H-2K or H-2D gene products of the target cell. This communication illustrates the generation of CTL showing specificity for I region determinants in primary mixed lymphocyte cultures. Further, we demonstrate by genetic analysis and byt eh use of speficit alloantisera that CTL directed to Ia determinants (a) do not see these antigens as modifications of H-2K or H-2D gene products but as independent gene products coded for by the I region, and (b) they do not require interaction with target cells bearing the same H-2K or H-2D gene product as the effect CTL

FAFSA and Beyond: How Advisers Manage Their Administrative Burden in the Financial Aid Process

Access to financial aid is crucial in ensuring that students can afford college. Students must file the FAFSA to access federal financial aid and usually the FAFSA is also required for state and institutional aid (U.S. Department of Education, n.d). Prior research has shown, however, that the FAFSA is complicated and burdensome to complete and often acts as a barrier instead of an entry point to college (Bettinger et al., 2012; Bird & Castleman, 2016; Dynarski & Scott-Clayton, 2006, 2008; Dynarski et al., 2013). Given these barriers in accessing aid, some high schools employ college advisers or other school staff to assist students in the financial aid process (Civic Enterprises, 2011; Dunlop Velez, 2016). This single case study explores how College Advising Corps (CAC) advisers perceived their role in the financial aid process and how they discuss college expenses, financial aid, and debt with students. Guided by social capital theory (Coleman, 1988) and administrative burden framework (Herd & Moynihan, 2018), we find that CAC advisers, in their role as a social capital resource, experience learning, psychological, and compliance costs when assisting students to navigate the financial aid bureaucracy. They employ different strategies to overcome, manage, and cope with these costs

Multi-scale continuum mechanics: from global bifurcations to noise induced high-dimensional chaos

Many mechanical systems consist of continuum mechanical structures, having either linear or nonlinear elasticity or geometry, coupled to nonlinear oscillators. In this paper, we consider the class of linear continua coupled to mechanical pendula. In such mechanical systems, there often exist several natural time scales determined by the physics of the problem. Using a time scale splitting, we analyze a prototypical structural–mechanical system consisting of a planar nonlinear pendulum coupled to a flexible rod made of linear viscoelastic material. In this system both low-dimensional and high-dimensional chaos is observed. The low-dimensional chaos appears in the limit of small coupling between the continua and oscillator, where the natural frequency of the primary mode of the rod is much greater than the natural frequency of the pendulum. In this case, the motion resides on a slow manifold. As the coupling is increased, global motion moves off of the slow manifold and high-dimensional chaos is observed. We present a numerical bifurcation analysis of the resulting system illustrating the mechanism for the onset of high-dimensional chaos. Constrained invariant sets are computed to reveal a process from low-dimensional to high-dimensional transitions. Applications will be to both deterministic and stochastic bifurcations. Practical implications of the bifurcation from low-dimensional to high-dimensional chaos for detection of damage as well as global effects of noise will also be discussed

Aeroelastic Model Structure Computation for Envelope Expansion

Structure detection is a procedure for selecting a subset of candidate terms, from a full model description, that best describes the observed output. This is a necessary procedure to compute an efficient system description which may afford greater insight into the functionality of the system or a simpler controller design. Structure computation as a tool for black-box modeling may be of critical importance in the development of robust, parsimonious models for the flight-test community. Moreover, this approach may lead to efficient strategies for rapid envelope expansion that may save significant development time and costs. In this study, a least absolute shrinkage and selection operator (LASSO) technique is investigated for computing efficient model descriptions of non-linear aeroelastic systems. The LASSO minimises the residual sum of squares with the addition of an l(Sub 1) penalty term on the parameter vector of the traditional l(sub 2) minimisation problem. Its use for structure detection is a natural extension of this constrained minimisation approach to pseudo-linear regression problems which produces some model parameters that are exactly zero and, therefore, yields a parsimonious system description. Applicability of this technique for model structure computation for the F/A-18 (McDonnell Douglas, now The Boeing Company, Chicago, Illinois) Active Aeroelastic Wing project using flight test data is shown for several flight conditions (Mach numbers) by identifying a parsimonious system description with a high percent fit for cross-validated data

'He just gave up': an exploratory study into the perspectives of paid carers on supporting older people living in care homes with depression, self-harm, and suicide ideation and behaviours

This study explored the concept of ‘giving up’ from the perspective of care staff working in care homes, and their everyday communication and hidden knowledge concerning what they think about this taboo topic and the context it reflects. Moving to a care home is a major transition where cumulative losses can pose risks to mental health in later life. If not recognised, this vulnerability can lead to depression which extends to suicide ideation and behaviours in the form of self-harm and self-neglect. Care homes are a significant place of care until death, yet a discourse of silence means that self-harm and suicide is under-reported or not attended to with specialist expertise. The layperson’s concept of an older person ‘giving up’ on life is hardly discussed in the literature. This co-produced qualitative study used an inductive approach to explore this phenomenon through focus groups with 33 care staff across four care homes in South-East England. Findings paint a complex picture, highlighting tensions in providing the right support and creating spaces to respond to such challenging situations. ‘Giving up’ requires skilled detailed assessment to respond to risks alongside improved training and support for paid carers, to achieve a more holistic strategy which capitalises on significant relationships within a wider context

Rab4 Orchestrates a Small GTPase Cascade for Recruitment of Adaptor Proteins to Early Endosomes

SummaryBackgroundEarly, sorting endosomes are a major crossroad of membrane traffic, at the intersection of the endocytic and exocytic pathways. The sorting of endosomal cargo for delivery to different subcellular destinations is mediated by a number of distinct coat protein complexes, including adaptor protein 1 (AP-1), AP-3, and Golgi-localized, gamma adaptin ear-containing, Arf-binding (GGAs) protein. Ultrastructural studies suggest that these coats assemble onto tubular subdomains of the endosomal membrane, but the mechanisms of coat recruitment and assembly at this site remain poorly understood.ResultsHere we report that the endosomal Rab protein Rab4 orchestrates a GTPase cascade that results in the sequential recruitment of the ADP-ribosylation factor (Arf)-like protein Arl1; the Arf-specific guanine nucleotide exchange factors BIG1 and BIG2; and the class I Arfs, Arf1 and Arf3. Knockdown of Arf1, or inhibition of BIG1 and BIG2 activity with brefeldin A results in the loss of AP-1, AP-3, and GGA-3, but not Arl1, from endosomal membranes and the formation of elongated tubules. In contrast, depletion of Arl1 randomizes the distribution of Rab4 on endosomal membranes, inhibits the formation of tubular subdomains, and blocks recruitment of BIG1 and BIG2, Arfs, and adaptor protein complexes to the endosome.ConclusionsTogether these findings indicate that Arl1 links Rab4-dependent formation of endosomal sorting domains with downstream assembly of adaptor protein complexes that constitute the endosomal sorting machinery