Seriation by constrained correspondence analysis: A simulation study

One of the many areas in which correspondence analysis (CA) is an effective method, concerns seriation problems. For example, CA is a well-known technique for the seriation of archaeological assemblages. A problem with the CA seriation solution, however, is that only a relative ordering of the assemblages is obtained. To improve the usual CA solution, a constrained CA approach that incorporates additional information in the form of equality and inequality constraints concerning the time points of the assemblages may be considered. Using such constraints, explicit dates can be assigned to the seriation solution. The set of constraints that can be used in CA by introducing interval constraints is extended. That is, constraints that put the CA solution within a specific time frame. Moreover, the quality of the constrained CA solution is studied in a simulation study. In particular, by means of the simulation study we are able to assess how well ordinary, and constrained CA can recover the true time order. Furthermore, for the constrained approach, it is shown that the true dates are retrieved satisfactory. The simulation study is set up in such a way that it mimics the data of a series of ceramic assemblages consisting of the locally produced tableware from Sagalassos (SW Turkey). It is found that the dating of the assemblages on the basis of constraints appears to work quite well.     

Confrontations with aggression and mental health problems in police officers: The role of organizational stressors, life-events and previous mental health problems.

The extent to which the frequency of facing aggression incidents is associated with mental health problems among police officers when organizational stressors, life-events, and previous mental health problems are taken into account is unclear. To elucidate this data from a longitudinal study of police officers was analyzed (N = 473). Mental health problems (MHPs) are here defined as severe anxiety, depression, hostility, burnout symptoms, and/or sleeping problems according the SCL-90–R and MBI. All MHPs were assessed at baseline and 27 months later. Logistic regression showed that serious threat was statistically significant associated with MHPs at follow-up among officers without MHPs at baseline, but not among those with MHPs at baseline. However, stepwise logistic regression showed that serious threat and/or physical aggression were not independently associated with MHPs at follow-up. Organizational stressors, that is, problems with colleagues were independent predictors in all analyses. Among the total study sample, previous MHPs were the strongest independent predictors. These findings suggest superiors should attend to the mental health, organizational stressors and life-events of their officers regularly and not only following critical incidents at work. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Construct Validation of the Dutch Version of the Impact of Event Scale.

The Impact of Event Scale (ES; M. J. Horowitz, N. Wilner, & W. Alvarez, 1979) is a worldwide-used self-report measure to assess the frequency of intrusive and avoidant phenomena after a variety of traumatic experiences. The purpose of this article is to assess the psychometric value of the Dutch version of the IES (D. Brom & R. J. Kleber, 1985) in several samples of individuals who had experienced various traumatic stressors. The reliability and structure of the IES were evaluated in 3 different samples (total N = 1.588). The reliability of the Dutch version of the IES was adequate across the various stressors. The construct validity was assessed by using confirmatory factor analyses. Outcomes revealed a robust structure over the various samples, generally supporting the composition of the original IES. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relationship between the plaque removal efficacy of a manual toothbrush and brushing force

The Charcot-Marie-Tooth disease type 1A (CMT1A) phenotype is most often associated with a 1.5 megabase (mb), tandem duplication of chromosome 17 band p12 (17p12). The prevailing hypothesis is that the demyelinating neuropathy results from a dosage effect of the peripheral myelin protein gene PMP22 which is included within this duplication. We present a patient with clinical and electrophysiological features of CMT1A in whom an extra PMP22 gene resulted from a rare unbalanced translocation of 17p to the X chromosome. This finding further supports the hypothesis of gene dosage as the basis for CMT1A. Moreover, this case highlights the importance of fluorescence in situ hybridization (FISH) as an alternative molecular technique in the diagnosis of CMT1A.     

Children referred for specialist care: a nationwide study in Dutch general practice

BACKGROUND: Insight into referral patterns provides general practitioners (GPs) and specialists with a frame of reference for their own work and enables assessment of the need for secondary care. Only approximate information is available. AIM: To determine how often, to which specialties and for what conditions children in different age groups are referred, as well as how often a condition is referred given the incidence in general practice. METHOD: From data of the Dutch National Survey of Morbidity and Interventions in General Practice, 63,753 new referrals (acute and non-acute) were analysed for children (0-14 years) from 103 participating practices (161 GPs) who registered. Practices were divided into four groups. Each group of practices participated for three consecutive months covering a whole year altogether. We calculated referral rates per 1000 children per year and referability rates per 100 episodes, which quantifies the a priori chance of a condition being referred for specialist care. RESULTS: The referral rate varied by age from 231 for children under 1 year old to 119 for those aged 10-14 years (mean 159). The specialties mainly involved were ENT, paediatrics, surgery, ophthalmology, dermatology and orthopaedics. Referrals in the first year of life were most frequently to paediatricians (123); among older children the referral rate to paediatricians decreased (mean 36). Referrals to ENT specialists were seen particularly in the age groups 1-4 (71) and 5-9 (53). For surgery, the referral rate increased by age from 19 to 34. Differences between boys and girls were small, except for surgery. The highest referral rates were for problems in the International Classification of Primary Care (ICPC) chapters: respiratory (28); musculoskeletal (25); ear (24) and eye (21). Referability rates were, in general, low for conditions referred to paediatrics and dermatology and high for surgery and ophthalmology. The variation in problems presented to each specialty is indicated by the proportion of all referrals constituted by the 10 most frequently referred diagnoses: from 35% for paediatrics to 81% for ENT; for ophthalmology, five diagnoses accounted for 83% of all referrals. CONCLUSIONS: The need for specialist care in childhood is clarified with detailed information for different age categories, specialties involved and variation in morbidity presented to specialists, as well as the proneness of conditions to be referred.     

New cation-exchange membranes for hyperfiltration processes

A new route for the preparation of cation exchange membranes from polystyrene–polyisoprene–polystyrene (SIS) block copolymers has been studied, using N-chlorosulfonyl isocyanate. At temperatures of 0° to 20°C, N-chlorosulfonyl isocyanate reacts readily with the olefin group in polyisoprenes, resulting in a β-lactam-N-sulfonyl chloride group. Films of this product can be cast which are hydrolyzed afterwards with aqueous ammonia at room temperature to give a membrane with ionic sulfonate and neutral carbamoyl groups. Homogeneous membranes are prepared with an SIS block copolymer as starting material and with mole ratios of N-chlorosulfonyl isocyanate/isoprene between 15% and 45%. In hyperfiltration experiments at 40 atmospheres, both NaCl and Na₂SO₄ are rejected up to 82%, while fluxes of 0.25 to 0.30 cm³/cm²·hr are obtained. From permeation and hyperfiltration experiments, it is concluded that the weight fraction of membrane water has a large influence on the flux. The water content in the membrane during the hyperfiltration process is primarily determined by the applied pressure, the type of salt, and its concentration.     

Non-olfactorial discrimination between foods by the dog

Simple coagulation studies were carried out in 18 patients with advanced Trypanosoma gambiense infection. No evidence of disseminated intravascular coagulation was found. Many patients had a moderate degree of thrombocytopenia which may have been due to enhanced splenic trapping of platelets. Most patients had raised levels of fibrin degradation products in their cerebrospinal fluid, perhaps reflecting the presence of underlying cerebral and meningeal vascular damage. Addition of viable trypanosomes or of trypanosome extracts to human and rat blood did not produce significant thrombocytopenia in vitro.     

Family physician consultation by patients with rheumatoid arthritis or gonarthrosis/coxarthrosis

OBJECTIVE: To determine how often patients with rheumatic joint disease consult their general practitioner (GP), and if there are disease and patient characteristics that influence GP consultation of gonarthrosis/coxarthrosis patients. DESIGN: Prospective record investigation. SETTING: Seven GP centres in the southeast of the Netherlands. METHOD: All patient contacts were registered prospectively in the seven GP centres: 46 concerned patients with rheumatoid arthritis (RA), 122 patients with gonarthrosis/ coxarthrosis. Patient and disease characteristics were collected on intake sheets. RESULTS: Three-quarters of the RA patients were periodically seen (mostly by a specialist), and 47% of the gonarthrosis/coxarthrosis patients (as often by their GP as by a specialist). Of the RA patients and of the gonarthrosis/coxarthrosis patients 74% and 89% respectively consulted their GPs in one year (the average numbers of contacts were 4.7 and 5.0); 50% and 57% did so because of the chronic joint disease (with 2.2 and 1.6 contacts respectively). No disease characteristics and only a few patient characteristics (arthroplasty, chronic use of medication) of patients with gonarthrosis/coxarthrosis influenced GP consultation. CONCLUSION: Patients with rheumatic joint disease often consult their GP, but not always because of this illness. If they consult their GP, they usually do so more than once a year.