Modelling geographic phenomena at multiple levels of detail: A model generalisation approach based on aggregation

Considerable interest remains in capturing once geographical information at the fine scale, and from this, automatically deriving information at various levels of detail and scale via the process of map generalisation. This research aims to develop a methodology for transformation of geographic phenomena at a high level of detail directly into geographic phenomena at higher levels of abstraction. Intuitive and meaningful interpretation of geographical phenomena requires their representation at multiple levels of detail. This is due to the scale dependent nature of their properties. Prior to the cartographic portrayal of that information, model generalisation is required in order to derive higher order phenomena typically associated with the smaller scales. This research presents a model generalisation approach able to support the derivation of phenomena typically present at 1:250,000 scale mapping, directly from a large scale topographic database (1:1250/1:2500/1:10,000). Such a transformation involves creation of higher order or composite objects, such as settlement, forest, hills and ranges, from lower order or component objects, such as buildings, trees, streets, and vegetation, in the source database. In order to perform this transformation it is important to model the meaning and relationships among source database objects rather than to consider the object in terms of their geometric primitives (points, lines and polygons). This research focuses on two types of relationships: taxonomic and partonomic. These relationships provide different but complimentary strategies for transformation of source database objects into required target database objects. The proposed methodology highlights the importance of partonomic relations for transformation of spatial databases over large changes in levels of detail. The proposed approach involves identification of these relationships and then utilising these relationships to create higher order objects. The utility of the results obtained, via the implementation of the proposed methodology, is demonstrated using spatial analysis techniques and the creation of ‘links’ between objects at different representations needed for multiple representation databases. The output database can then act as input to cartographic generalisation in order to create maps (digital or paper). The results are evaluated using manually generalised datasets

Exploring representational issues in the visualisation of geographical phenomenon over large changes in scale.

It is only at small scales that we get a synoptic view of the world. That synoptic view is composed of highly characteristic forms – these forms representing ‘ideas’ or concepts, and their location. In the example (Figure 1) a mix of text and a highly generalised representation of the road network are used to delineate the concept ‘city’ – in this case London

Rural and Urban Road Network Generalisation: Deriving 1:250,000 from OS MasterMap

Roads are essential component of topographic maps and spatial databases. The challenge in automated generalisation of road networks is to derive a connected network while maintaining the structure for the intended target scale and to achieve this with minimum user intervention. A lot of methods to select, displace and simplify roads have been presented; the focus here is on the generalisation of networks using visual perception techniques. This paper presents a framework based on visual perception that uses minimum attributes for generalisation of both ‘rural’ and ‘urban’ roads over large scale change. The system incorporated graph theoretic techniques to explicitly model the topology of the network as it was generalized. The model uses a fine scale map (1:1250 or 1:2500) as input and generates small scale (1:250,000) maps directly from it without creating intermediate small scale maps. The results compared favorably with paper maps (Ordnance Surveys Stratgie dataset (1:250,000))

Visualisation of Settlements Over Large Changes In Scale

This paper explores the application of map generalisation techniques in the creation of small scale mapping (1:250,000) directly from large scale data (1:1250 and 1:2500). Small scale mapping provides a synoptic overview. At 1:250,000 scale, it is not that there is less information contained in the map, rather that we see fundamentally different information and relationships – broad-brush information between higher order phenomenon. The evaluation criteria used at this scale are quite different from those used at large scale. This paper describes a methodology by which small scale mapping is derived directly from the large scale (without generating intermediate results) using simple generalisation techniques. The approach illustrated in this case study, creates city boundaries based on simple buffering of building features, and derivation of the single polygon surrounding clusters of buildings over a threshold size. The hull is simplified, small internal polygons removed. The algorithm was applied to large and small conurbations alike. The results obtained via this method were evaluated against paper maps. Initial results point to refinement of this technique

A randomised double-blind placebo-controlled trial of minocycline and/or Omega-3 fatty acids added to treatment as usual for At Risk Mental States (NAYAB): study protocol

Background The At Risk Mental State (ARMS) describes individuals at high risk of developing schizophrenia or psychosis. The use of antipsychotics in this population is not supported because most individuals with ARMS are unlikely to develop psychosis. Anti-inflammatory treatments and polyunsaturated fatty acids (PUFAs) may have some beneficial effects in the treatment of ARMS. There have been no controlled clinical trials that have investigated the use of minocycline for ARMS and no trials involving PUFAs in combination with other proposed treatments. There is a need to find effective, tolerable and inexpensive interventions for ARMS that are available both in high, low and middle-income countries. Methods A six-month intervention study of minocycline and/or Omega-3 fatty acids added to treatment as usual (TAU) in patients with ARMS will be conducted in Pakistan using a randomised, placebo-controlled, double-blind factorial design. 320 consenting patients with capacity will be recruited from community, general practitioner clinics and psychiatric units. Allowing for a 25% dropout rate, we will recruit 59 completing participants to each study arm, and 236 will complete in total. We will determine whether the addition of minocycline and/or Omega-3 fatty acids to TAU attenuates rate of transition from ARMS to first-episode psychosis and improves symptoms and/or level of functioning in ARMS. We will also investigate whether any candidate risk factors such as negative symptoms, influence treatment response in the ARMS group. The primary efficacy end-point is conversion to psychotic disorder at 12 months post study entry. Analysis will be by intention-to-treat, using analysis-of variance, chi-squared tests and adjusted odds ratios to assess between-group differences. Cox regression analyses will be used to analyse potential between-group differences in time-to-onset of psychosis. Discussion The outcomes of this trial will provide evidence of the potential benefits of minocycline and PUFAs in the treatment of ARMS. Both minocycline and PUFAs are inexpensive are readily available in low/middle-income countries such as Pakistan, and if evidenced, may prove to be safe and effective for treating ARMS

Prevalence of depression and anxiety in patients with chronic obstructive pulmonary disease and their association with psychosocial outcomes: A cross-sectional study from Pakistan.

ObjectivesChronic obstructive pulmonary disease contributes to substantial health and economic burden worldwide. Co-morbid depression and anxiety are highly prevalent in patients with chronic obstructive pulmonary disease. Depressive symptoms in chronic obstructive pulmonary disease are associated with poorer survival, longer hospitalisation and impaired quality of life. Literature on chronic obstructive pulmonary disease is largely derived from high-income countries; yet 90% of deaths related to chronic obstructive pulmonary disease occur in low- and middle-income countries. We aimed to establish the prevalence of anxiety and depression in patients with chronic obstructive pulmonary disease, as well as the association with psychosocial outcomes.MethodsThis was a cross-sectional study of chronic obstructive pulmonary disease patients attending outpatient primary care clinics in Karachi, Pakistan. The Patient Health Questionnaire-9 was used to assess depression and the Generalised Anxiety Disorder-7 scale was used for the assessment of anxiety. Health-related quality of life was assessed with EuroQol-Five Dimensions, social support with Oslo-3 and social stress with Life Events Checklist. We recruited 293 subjects.ResultsThe prevalence of depression and anxiety in the sample was 51% (n = 149) and 20% (n = 59), respectively. Depressed chronic obstructive pulmonary disease patients reported significantly lower health-related quality of life scores as compared to non-depressed patients. Participants with depression had significantly higher levels of anxiety, less social support, higher social stress and more subjective impairment in quality of life.ConclusionGiven the association with reduced social support and increased perceived stress, the role of psychosocial interventions must be explored in improving outcomes of chronic obstructive pulmonary disease patients in Pakistan

Prevalence of suicidal ideation and suicide attempts in individuals with psychosis and bipolar disorder in South Asia: systematic review and meta-analysis.

BackgroundSuicidal ideation and attempts are growing public health concerns globally. Evidence from high-income countries suggests that individuals with psychosis and bipolar disorder are at increased risk of suicidal ideation and attempts, but there is a scarcity of evidence from South Asia.AimsTo estimate the prevalence of suicidal ideation and attempts in individuals with psychosis and bipolar disorder in South Asia.MethodIn this systematic review and meta-analysis, four databases (PsycINFO, Web of Science, EMBASE and Medline) were searched until December 2022. Pooled prevalence was estimated with random-effects models. Heterogeneity was quantified with the I2-statistic.ResultsThe pooled sample size across the 21 studies was 3745 participants, 1941 (51.8%) of which were male. The pooled prevalence of suicide attempts in South Asian people with either psychosis or bipolar disorder was 22% (95% CI 17-27; n = 15). The pooled prevalence of suicidal ideation with psychosis or bipolar disorder combined was 38% (95% CI 27-51; n = 10). Meta-regression, subgroup and sensitivity analysis showed that the pooled prevalence estimates for both suicide attempt and ideation remained unaffected by variations in critical appraisal ratings and study designs. Only one study reported data on suicide-related deaths.ConclusionsOne in four individuals diagnosed with psychosis or bipolar disorder have reported suicide attempts, whereas up to one in three have experienced suicidal ideation. These findings underscore the urgent need for clinicians to regularly assess and monitor suicidal ideation and attempts among individuals with these disorders in South Asia

A randomised double-blind placebo-controlled trial of minocycline and/or omega-3 fatty acids added to treatment as usual for at risk Mental States: The NAYAB study.

BackgroundInflammatory mechanisms are thought to contribute to the onset of psychosis in persons with an at-risk mental state (ARMS). We investigated whether the anti-inflammatory properties of minocycline and omega-3 polyunsaturated fatty acids (omega-3), alone or synergistically, would prevent transition to psychosis in ARMS in a randomised, double-blind, placebo-controlled trial in Pakistan.Methods10,173 help-seeking individuals aged 16-35 years were screened using the Prodromal Questionaire-16. Individuals scoring 6 and over were interviewed using the Comprehensive Assessment of At-Risk Mental States (CAARMS) to confirm ARMS. Participants (n = 326) were randomised to minocycline, omega-3, combined minocycline and omega-3 or to double placebo for 6 months. The primary outcome was transition to psychosis at 12 months.FindingsForty-five (13.8 %) participants transitioned to psychosis. The risk of transition was greater in those randomised to omega-3 alone or in combination with minocycline (17.3.%), compared to 10.4 % in those not exposed to omega-3; a risk-ratio (RR) of 1.67, 95 % CI [0.95, 2.92] p = 0.07. The RR for transitions on minocycline vs. no minocycline was 0.86, 95 % CI [0.50, 1.49] p > 0.10. In participants who did not become psychotic, CAARMS and depression symptom scores were reduced at six and twelve months (mean CAARMS difference = 1.43; 95 % CI [0.33, 1.76] p InterpretationIn keeping with other studies, omega-3 appears to have beneficial effects on ARMS and mood symptom severity but it increased transition to psychosis, which may reflect metabolic or developmental consequences of chronic poor nutrition in the population. Transition to psychosis was too rare to reveal a preventative effect of minocycline but minocycline did not improve symptom severity. ARMS symptom severity and transition to psychosis appear to have distinct pathogeneses which are differentially modulated by omega-3 supplementation.FundingThe study was funded by the Stanley Research Medical Institute