On Recurrent Reachability for Continuous Linear Dynamical Systems

The continuous evolution of a wide variety of systems, including continuous-time Markov chains and linear hybrid automata, can be described in terms of linear differential equations. In this paper we study the decision problem of whether the solution $\boldsymbol{x}(t)$ of a system of linear differential equations $d\boldsymbol{x}/dt=A\boldsymbol{x}$ reaches a target halfspace infinitely often. This recurrent reachability problem can equivalently be formulated as the following Infinite Zeros Problem: does a real-valued function $f:\mathbb{R}_{\geq 0}\rightarrow\mathbb{R}$ satisfying a given linear differential equation have infinitely many zeros? Our main decidability result is that if the differential equation has order at most $7$, then the Infinite Zeros Problem is decidable. On the other hand, we show that a decision procedure for the Infinite Zeros Problem at order $9$ (and above) would entail a major breakthrough in Diophantine Approximation, specifically an algorithm for computing the Lagrange constants of arbitrary real algebraic numbers to arbitrary precision.Comment: Full version of paper at LICS'1

Inflammatory bowel disease-specific autoantibodies in HLA-B27-associated spondyloarthropathies: Increased prevalence of ASCA and pANCA

Aims: An association between inflammatory bowel disease (IBD) and spondyloarthropathies (SpA) has repeatedly been reported. The aim of the present study was to investigate whether serologic markers of IBD, e. g. antibodies against Saccharomyces cerevisiae (ASCA), antibodies against exocrine pancreas (PAB) and perinuclear antineutrophil cytoplasmic antibodies (pANCA) are present in HLA-B27-associated SpA. Methods: 87 patients with HLA-B27-positive SpA and 145 controls were tested for ASCA, PAB and pANCA employing ELISA or indirect immunofluorescence, respectively. Antibody-positive patients were interviewed regarding IBD-related symptoms using a standardized questionnaire. Results/Conclusion: When compared to the controls, ASCA IgA but not ASCA IgG levels were significantly increased in patients with SpA, in particular in ankylosing spondylitis (AS) and undifferentiated SpA (uSpA). pANCA were found in increased frequency in patients with SpA whereas PAB were not detected. The existence of autoantibodies was not associated with gastrointestinal symptoms but sustains the presence of a pathophysiological link between bowel inflammation and SpA. Copyright (C) 2004 S. Karger AG, Basel

Bush Encroachment and Large Carnivore Predation Success in African Landscapes:A Review

Bush encroachment is a habitat change phenomenon that threatens savanna and grassland ecosystems worldwide. In Africa, large carnivores in bush encroached landscapes must adjust to increasing woody plant cover and biomass, which could affect predation success at multiple stages through complex and context-dependent pathways. We highlight, interpret, and compare studies that assessed how bush encroachment or related habitat parameters affect the predation stages of large African carnivores. Bush encroachment may directly or indirectly affect predation success in various ways, including by: (1) altering habitat structure, which may affect hunting efficiency and prey accessibility; (2) changing prey abundance/distribution, with smaller species and browsers being potentially favoured; (3) influencing interference competition within the carnivore guild. For habitat or dietary specialists, and subordinate predators that are vulnerable to both top-down and bottom-up ecosystem effects, these alterations may be detrimental and eventually incur population fitness costs. As the threat of bush encroachment continues, future studies are required to assess indirect effects on competitive interactions within the large African carnivore guild to ensure that conservation efforts are focused. Additionally, to better understand the effects of bush encroachment across Africa, further research is necessary in affected areas as overall little attention has been devoted to the topic

Effect of psychiatry liaison with general practitioners on depression severity in recently hospitalised cardiac patients: a randomised controlled trial

The document attached has been archived with permission from the editor of the Medical Journal of Australia (26 April 2007). An external link to the publisher’s copy is included.Objective: To evaluate the effect on depressive symptoms in cardiac patients of patient-specific advice to general practitioners regarding management of comorbid depression. Design and setting: A randomised controlled trial in four general hospitals in Adelaide, South Australia. Participants: Patients (n = 669) admitted to cardiology units for a range of cardiovascular conditions who were screened and assessed as being depressed according to the Center for Epidemiological Studies Depression Scale (CES-D). Intervention: Inpatient psychiatric review, followed by telephone case conferencing between specialist hospital staff and GPs to provide patient-specific information about the patient’s depression and its management, educational material, and ongoing clinical support. Main outcome measures: Level of depression severity at 12 months posthospitalisation. Results: On the basis of intention to treat, intervention patients had lower rates of moderate to severe depression (CES-D ≥ 27) after 12 months (25% v 35%, relative risk, 0.72; 95% CI, 0.54–0.96, number needed to treat for benefit, 11). The intervention was most effective in preventing progression from mild depression to moderate to severe depression. The multidisciplinary telephone case conferencing was difficult to implement and, in a post hoc analysis, brief phone advice from a psychiatrist was found to be effective. Conclusions: Screening hospitalised cardiac patients for depression and providing targeted advice to their GPs reduces depression severity 12 months after hospitalisation.Geoff Schrader, Frida Cheok, Ann-Louise Hordacre, Julie Marker and Victoria Wad

Depression after cardiac hospitalisation: the identifying depression as a comorbid condition (IDACC) study

Copyright © 2005 Royal Australian College of General Practitioners Copyright to Australian Family Physician. Reproduced with permission. Permission to reproduce must be sought from the publisher, The Royal Australian College of General Practitioners.Background: The Identifying Depression as a Comorbid Condition (IDACC) study aimed to identify depressive symptoms in hospitalised cardiac patients and support management of depression in general practice. Objective: This post hoc analysis of the IDACC trial examines the effectiveness and practicality of different forms of communication between hospital psychiatric services and general practitioners. Methods: We randomised 669 cardiac inpatients with depressive symptoms, identified with the Center for Epidemiological Studies Depression Scale (CES-D), to an intervention or usual care control group. Individual depression scores and depression management guidelines were sent to GPs of all intervention patients. Where possible, psychiatric advice was provided to the GP either by multidisciplinary enhanced primary care case conference or one-to-one telephone advice. Results: Multidisciplinary case conferences were implemented for only 24% of intervention patients. General practitioners received individual telephone advice in 40% of cases, and 36% received written information only. The psychiatrist telephone advice resulted in a significant reduction in the proportion of patients with moderate to severe depression 12 months after cardiac hospitalisation (19% vs. 35%). Discussion: Screening, combined with psychiatrist telephone advice to GPs, was simple to organise and effective in reducing depression severity after cardiac admission.Victoria Wade, Frida Cheok, Geoff Schrader, Ann-Louise Hordacre and Julie Marke

Depression after cardiac hospitalisation: the identifying depression as a comorbid condition (IDACC) study

Copyright © 2005 Royal Australian College of General Practitioners Copyright to Australian Family Physician. Reproduced with permission. Permission to reproduce must be sought from the publisher, The Royal Australian College of General Practitioners.Background: The Identifying Depression as a Comorbid Condition (IDACC) study aimed to identify depressive symptoms in hospitalised cardiac patients and support management of depression in general practice. Objective: This post hoc analysis of the IDACC trial examines the effectiveness and practicality of different forms of communication between hospital psychiatric services and general practitioners. Methods: We randomised 669 cardiac inpatients with depressive symptoms, identified with the Center for Epidemiological Studies Depression Scale (CES-D), to an intervention or usual care control group. Individual depression scores and depression management guidelines were sent to GPs of all intervention patients. Where possible, psychiatric advice was provided to the GP either by multidisciplinary enhanced primary care case conference or one-to-one telephone advice. Results: Multidisciplinary case conferences were implemented for only 24% of intervention patients. General practitioners received individual telephone advice in 40% of cases, and 36% received written information only. The psychiatrist telephone advice resulted in a significant reduction in the proportion of patients with moderate to severe depression 12 months after cardiac hospitalisation (19% vs. 35%). Discussion: Screening, combined with psychiatrist telephone advice to GPs, was simple to organise and effective in reducing depression severity after cardiac admission.Victoria Wade, Frida Cheok, Geoff Schrader, Ann-Louise Hordacre and Julie Marke

Tameness of holomorphic closure dimension in a semialgebraic set

Given a semianalytic set S in a complex space and a point p in S, there is a unique smallest complex-analytic germ at p which contains the germ of S, called the holomorphic closure of S at p. We show that if S is semialgebraic then its holomorphic closure is a Nash germ, for every p, and S admits a semialgebraic filtration by the holomorphic closure dimension. As a consequence, every semialgebraic subset of a complex vector space admits a semialgebraic stratification into CR manifolds satisfying a strong version of the condition of the frontier.Comment: Published versio