Improved Approximate String Matching and Regular Expression Matching on Ziv-Lempel Compressed Texts

We study the approximate string matching and regular expression matching problem for the case when the text to be searched is compressed with the Ziv-Lempel adaptive dictionary compression schemes. We present a time-space trade-off that leads to algorithms improving the previously known complexities for both problems. In particular, we significantly improve the space bounds, which in practical applications are likely to be a bottleneck

Distinguishing environmental effects on binary black hole gravitational waveforms

Future gravitational wave interferometers such as the Laser Interferometer Space Antenna, Taiji, DECi-hertz Interferometer Gravitational wave Observatory and TianQin will enable precision studies of the environment surrounding black holes. These detectors will probe the millihertz frequency range, as yet unexplored by current gravitational wave detectors. Furthermore, sources will remain in band for durations of up to years, meaning that the inspiral phase of the gravitational wave signal, which can be affected by the environment, will be observable. In this paper, we study intermediate and extreme mass ratio binary black hole inspirals, and consider three possible environments surrounding the primary black hole: accretion disks, dark matter spikes and clouds of ultra-light scalar fields, also known as gravitational atoms. We present a Bayesian analysis of the detectability and measurability of these three environments. Focusing for concreteness on the case of a detection with LISA, we show that the characteristic imprint they leave on the gravitational waveform would allow us to identify the environment that generated the signal and to accurately reconstruct its model parameters.</p

Psychosocial support for families of children with neurodisability who have or are considering a gastrostomy: the G-PATH mixed-methods study

Background Evidence reviews recommend consistent and structured support for children with neurodisability and their caregivers in care pathways in which professionals recommend a gastrostomy feeding tube. To date, and to our knowledge, no research has shown how these recommendations have been implemented. Objectives The objectives were to describe different exemplar models of psychosocial support and provide an estimate of their resources and costs. Design This was a mixed-methods study involving (1) a web-based survey, (2) a qualitative, collective case study of psychosocial support provision in four services and (3) an estimate of costs and preference through a willingness-to-pay study. Setting Four service configurations in different locations in England and Scotland. Participants Participants were staff who responded to a survey (n = 67) and interviewees (staff, n = 58; parents/children, n = 29). Findings Psychosocial support was rarely formalised or documented; it was delivered by different members of the multidisciplinary team, rather than by designated staff, and it was often integrated into appointments dominated by clinical care. Parents expressed different needs for support but reported little opportunity to discuss emotional aspects. Psychologists were not routinely involved and, in general, families were underserved by psychosocial services. Professionals constructed families’ need for psychosocial support in terms of their own roles and the management of risk. Mechanisms for integrating and delivering support were identified, including models of care that linked community and tertiary health services and integrated health and education through pooled budgets. Although generally valued by both staff and parents, peer-to-peer parent support was not consistently offered. Barriers included concerns about confidentiality and appropriately matching parents. Parents participated as members of a feeding committee at one site. Three analytical constructs described the provision of psychosocial support: ‘hidden work’, expressing emotional vulnerability and negotiations around risks and values. The cost-of-support study found that there was a mean of 2.25 appointments (n = 8 parents or carers) over the previous 12 months. The cost of health-care professionals’ time spent on providing psychosocial support ranged from £0.00 to £317.37 per child per year, with an average cost of £76.42, at 2017 prices. In the willingness-to-pay study the median rank of enhanced support, involving the opportunity to see a psychologist and parental peers, was significantly higher than that of usual care (n = 96 respondents, both carers and professionals, who completed rating of the service; p < 0.001). Limitations It proved difficult to disseminate a national survey, which resulted in a small number of returns, and to cost the provision of psychosocial support, which we designated as ‘hidden work’, owing to the lack of recording in clinical systems. Moreover, estimates were based on small numbers. Conclusions Parent interviews and the willingness-to-pay study demonstrated a preference for enhanced psychosocial support. The study suggests that there is a need for services to formally assess families’ needs for psychosocial support to ensure that provision is planned, costed and made explicit in care pathways. Personalised interventions may assist with the targeting of resources and ensuring that there is an appropriate balance in focus on both clinical care and psychosocial support needs in relation to and following treatment. Future work More work is needed to develop tools to assess families’ needs for psychosocial support and the effectiveness of training packages to strengthen team competency in providing support. Funding This project was funded by the National Institute for Health Research (NIHR) Health Services and Delivery Research programme and will be published in full in Health Services and Delivery Research; Vol. 8, No. 38. See the NIHR Journals Library website for further project information

Distribution function approach to redshift space distortions. Part IV: perturbation theory applied to dark matter

We develop a perturbative approach to redshift space distortions (RSD) using the phase space distribution function approach and apply it to the dark matter redshift space power spectrum and its moments. RSD can be written as a sum over density weighted velocity moments correlators, with the lowest order being density, momentum density and stress energy density. We use standard and extended perturbation theory (PT) to determine their auto and cross correlators, comparing them to N-body simulations. We show which of the terms can be modeled well with the standard PT and which need additional terms that include higher order corrections which cannot be modeled in PT. Most of these additional terms are related to the small scale velocity dispersion effects, the so called finger of god (FoG) effects, which affect some, but not all, of the terms in this expansion, and which can be approximately modeled using a simple physically motivated ansatz such as the halo model. We point out that there are several velocity dispersions that enter into the detailed RSD analysis with very different amplitudes, which can be approximately predicted by the halo model. In contrast to previous models our approach systematically includes all of the terms at a given order in PT and provides a physical interpretation for the small scale dispersion values. We investigate RSD power spectrum as a function of \mu, the cosine of the angle between the Fourier mode and line of sight, focusing on the lowest order powers of \mu and multipole moments which dominate the observable RSD power spectrum. Overall we find considerable success in modeling many, but not all, of the terms in this expansion.Comment: 37 pages, 13 figures, published in JCA

Faster Approximate String Matching for Short Patterns

We study the classical approximate string matching problem, that is, given strings $P$ and $Q$ and an error threshold $k$, find all ending positions of substrings of $Q$ whose edit distance to $P$ is at most $k$. Let $P$ and $Q$ have lengths $m$ and $n$, respectively. On a standard unit-cost word RAM with word size $w \geq \log n$ we present an algorithm using time $$O(nk \cdot \min(\frac{\log^2 m}{\log n},\frac{\log^2 m\log w}{w}) + n)$$ When $P$ is short, namely, $m = 2^{o(\sqrt{\log n})}$ or $m = 2^{o(\sqrt{w/\log w})}$ this improves the previously best known time bounds for the problem. The result is achieved using a novel implementation of the Landau-Vishkin algorithm based on tabulation and word-level parallelism.Comment: To appear in Theory of Computing System

Statistical properties of the Burgers equation with Brownian initial velocity

We study the one-dimensional Burgers equation in the inviscid limit for Brownian initial velocity (i.e. the initial velocity is a two-sided Brownian motion that starts from the origin x=0). We obtain the one-point distribution of the velocity field in closed analytical form. In the limit where we are far from the origin, we also obtain the two-point and higher-order distributions. We show how they factorize and recover the statistical invariance through translations for the distributions of velocity increments and Lagrangian increments. We also derive the velocity structure functions and we recover the bifractality of the inverse Lagrangian map. Then, for the case where the initial density is uniform, we obtain the distribution of the density field and its $n$-point correlations. In the same limit, we derive the $n-$point distributions of the Lagrangian displacement field and the properties of shocks. We note that both the stable-clustering ansatz and the Press-Schechter mass function, that are widely used in the cosmological context, happen to be exact for this one-dimensional version of the adhesion model.Comment: 42 pages, published in J. Stat. Phy

Identifying a gender-inclusive pedagogy from Maltese science teachers' personal practical knowledge

Teachers bring with them into the science classrooms their own gendered identitities and their views and perceptions about how boys and girls learn and achieve in science. This paper tries to explore the way in which fourteen Maltese science teachers use their own 'personal practical knowledge' to identify their views about gender and science and create their own individual gender-inclusive pedagogy. The study suggests that the science teachers focus more on the individuality of students and on the social and cultural background of the students in their classrooms rather than on gender. The teachers try to develop pedagogies and assessment practices which take into consideration the personal constructs of individual learners. The ideas for such a gender-inclusive pedagogy emerge from their common-sense experience in the classroom, their training as teachers and are closely interrelated to current ideas of social constructivism

Comparing neighborhood and state contexts for women living with and without HIV: Understanding the southern HIV epidemic

In the South, people living with HIV experience worse health outcomes than in other geographic regions, likely due to regional political, structural, and socioeconomic factors. We describe the neighborhoods of women (n = 1,800) living with and without HIV in the Women’s Interagency HIV Study (WIHS), a cohort with Southern sites in Chapel Hill, NC; Atlanta, GA; Birmingham, AL; Jackson, MS; and Miami, FL; and non-Southern sites in Brooklyn, NY; Bronx, NY; Washington, DC; San Francisco, CA; and Chicago, IL. In 2014, participants’ addresses were geocoded and matched to several administrative data sources. There were a number of differences between the neighborhood contexts of Southern and non-Southern WIHS participants. Southern states had the lowest income eligibility thresholds for family Medicaid, and consequently higher proportions of uninsured individuals. Modeled proportions of income devoted to transportation were much higher in Southern neighborhoods (Location Affordability Index of 28–39% compared to 16–23% in non-Southern sites), and fewer participants lived in counties where hospitals reported providing HIV care (55% of GA, 63% of NC, and 76% of AL participants lived in a county with a hospital that provided HIV care, compared to >90% at all other sites). Finally, the states with the highest adult incarceration rates were all in the South (per 100,000 residents: AL 820, MS 788, GA 686, FL 644). Many Southern states opted not to expand Medicaid, invest little in transportation infrastructure, and have staggering rates of incarceration. Resolution of racial and geographic disparities in HIV health outcomes will require addressing these structural barriers

Young and Intermediate-age Distance Indicators

Distance measurements beyond geometrical and semi-geometrical methods, rely mainly on standard candles. As the name suggests, these objects have known luminosities by virtue of their intrinsic proprieties and play a major role in our understanding of modern cosmology. The main caveats associated with standard candles are their absolute calibration, contamination of the sample from other sources and systematic uncertainties. The absolute calibration mainly depends on their chemical composition and age. To understand the impact of these effects on the distance scale, it is essential to develop methods based on different sample of standard candles. Here we review the fundamental properties of young and intermediate-age distance indicators such as Cepheids, Mira variables and Red Clump stars and the recent developments in their application as distance indicators.Comment: Review article, 63 pages (28 figures), Accepted for publication in Space Science Reviews (Chapter 3 of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Age