Persistence of long-distance, insect-mediated pollen movement for a tropical canopy tree species in remnant forest patches in an urban landscape.

As deforestation and urbanization continue at rapid rates in tropical regions, urban forest patches are essential repositories of biodiversity. However, almost nothing is known about gene flow of forest-dependent tree species in urban landscapes. In this study, we investigated gene flow in the insect-pollinated, wind-dispersed tropical tree Koompassia malaccensis in and among three remnant forest patches in the urbanized landscape of Singapore. We genotyped the vast majority of adults (N=179) and a large number of recruits (N=2103) with 8 highly polymorphic microsatellite markers. Spatial genetic structure of the recruit and adult cohorts was significant, showing routine gene dispersal distances of ~100-400 m. Parentage analysis showed that 97% of recruits were within 100 m of their mother tree, and a high frequency of relatively short-distance pollen dispersal (median ~143-187 m). Despite routine seed and pollen dispersal distances of within a few hundred meters, interpatch gene flow occurred between all patches and was dominated by pollen movement: parentage analysis showed 76 pollen versus 2 seed interpatch dispersal events, and the seedling neighborhood model estimated ~1-6% seed immigration and ~21-46% pollen immigration rates, depending on patch. In addition, the smallest patch (containing five adult K. malaccensis trees) was entirely surrounded by >2.5 km of 'impervious' substrate, yet had the highest proportional pollen and seed immigration estimates of any patch. Hence, contrary to our hypothesis, insect-mediated gene flow persisted across an urban landscape, and several of our results also parallel key findings from insect-pollinated canopy trees sampled in mixed agricultural-forest landscapes.

The teaching of trauma management in undergraduate medical education.

BACKGROUND: The teaching of trauma in medical schools faces many educational and logistic challenges. Issues on what to teach, how to teach, when to teach, who will teach and whether medical students with insufficient exposure to clinical medicine can benefit from a trauma course are unclear. MATERIALS AND METHODS: A well-designed one day intensive trauma course concentrating on the primary survey was taught to semester seven and semester eight students by a multi-disciplinary team comprising of surgeons, anaesthetists, emergency physicians and trained medical officers. The course comprised of a pre-test of 30 multiple choice questions followed by three hours of lectures, three hours of skill stations and a post-test. The pre-test and posttest scores were analysed using the paired sample t-test and the independent t-test. RESULTS: The pre- and post-test scores showed significant improvement for both semester seven and semester eight students. Semester seven students, who only had a sevenweek posting in Surgery had pre-test and post-test scores of only 4% less than semester eight students who had an additional six weeks in Orthopaedics and two weeks in Accident and Emergency postings. The use of a multidisciplinary team reduced the logistic burden of finding sufficient surgeons to teach trauma management. CONCLUSION: Trauma education can be taught to undergraduates by a multidisciplinary team as early as year three, in semester seven. However, the mean score of semester eight students is only at 66%, suggesting that a refresher course prior to graduation at semester ten will be useful. KEY WORDS.

Retention of Knowledge following training of students in Basic Trauma Life Support.

INTRODUCTION: In the course of their undergraduate training at the International Medical University, students receive a Basic Trauma Life Support course. OBJECTIVE: We wanted to test the long-term retention of knowledge (after 16 months) of third year medical students who had received training in Basic Trauma Life Support Method: To assess the retention of knowledge one cohort of students who received the training course were tested again 16 months later using the same 30 question One Best Answer quiz. RESULTS: Seventy-three students who underwent the course sat for the Retention test. The number of students who passed the Retention test was not significantly different from the test taken immediately after the course. The mean scores, 62.5% and 59.5% respectively, were however significantly different. CONCLUSION: Our study involves a relatively long interval between the course and retention of knowledge test shows encouraging results.

Embryonal rhabdomyosarcoma of the middle ear presenting with aural polyp and facial nerve palsy.

Rhabdomyosarcoma is a rare tumour in the middle ear and mastoid cavity in children and the diagnosis is difficult. Repeated histological examination may be essential to confirm the diagnosis. We report a 6 year old boy with a left aural polyp, otorrhoea and facial nerve palsy who was initially thought to have otitis media and mastoiditis. He had polypectomy and the tissue taken for histopathology suggested an inflammatory condition. Subsequently he had mastoidectomy. Tissue taken during mastoidectomy was however reported as rhabdomyosarcoma. The child developed a cerebral abscess and eventually succumbed. A literature review of the disease, radiological findings, immunohistochemical features and treatment options is described.

Rapid reversal of subclinical hyperthyroidism in patients with large multinodular goitres after thyroidectomy.

A patient is said to have subclinical hyperthyroidism if he has a depressed thyroid stimulating hormone (TSH) level but is clinically euthyroid and has a normal thyroxine (T4) and triiodothyronine (T3) level. The aetiology of this condition is unknown, its progression is uncertain and the value of treatment is doubtful. These 2 cases show a rapid reversal of TSH suppression within a week after thyroidectomy. This suggest an unidentified potent but innocuous suppressor of TSH is produced by some large nodular goitres. Patients with multinodular goitres with subclinical hyperthyroidism can have their anxiety allayed with assurance that their condition is benign and that their TSH suppression is due to the presence of an innocuous substance which is protective in nature. This substance, when isolated, will find a useful place in the prevention and treatment of papillary carcinoma of the thyroid because of its potent effect on the pituitary-thyroid axis without causing any peripheral effects.

Evolution of myrmecophytism in western Malesian Macaranga (Euphorbiaceae).

Plants inhabited by ants (myrmecophytes) have evolved in a diversity of tropical plant lineages. Macaranga includes approximately 300 paleotropical tree species; in western Malesia there are 26 myrmecophytic species that vary in morphological specializations for ant association. The origin and diversification of myrmecophytism in Macaranga was investigated using phylogenetic analyses of morphological and nuclear ITS DNA characters and studies of character evolution. Despite low ITS variation, the combined analysis resulted in a well-supported hypothesis of relationships. Mapping myrmecophytism on all most parsimonious trees resulting from the combined analysis indicated that the trait evolved independently between two and four times and was lost between one and three times (five changes). This hypothesis was robust when tested against trees constrained to have three or fewer evolutionary transformations, although increased taxon sampling for the ITS analysis is required to confirm this. Mapping morphological traits on the phylogeny indicated that myrmecophytism was not homologous among lineages; each independent origin involved a suite of different specializations for ant-plant association. There was no evidence that myrmecophytic traits underwent sequential change through evolution; self-hollowing domatia evolved independently from ant-excavated domatia, and different food-body production types evolved in different lineages. The multiple origins of myrmecophytism in Macaranga were restricted to one small, exclusively western Malesian lineage of an otherwise large and nonmyrmecophytic genus. Although the evolution of aggregated food-body production and the formation of domatia coincided with the evolution of myrmecophytism in all cases, several morphological, ecological, and biogeographic factors appear to have facilitated and constrained this radiation of ant-plants.

Powder densification. 1. Particle-particle basis for incorporation of viscoelastic material properties.

The present investigation was undertaken to examine the basic unit of densification: the particle-particle indentation. The true interparticle contact area that is established during densification ultimately determines the quality of the tablet compact. By examining the interfacial contact between mutually indenting viscoelastic particles, the process of contact evolution may be represented in mathematical form through extension of the classical Hertzian elastic contact description to encompass material viscoelastic terms. In this way, the time-dependent response of materials to applied loads may be addressed explicitly. The effects of rates of applied loading and maximum load levels were also considered. This analysis was based on viscoelastic stress data collected using an instrumented Instron analyzer during the densification of PMMA/coMMA, a pharmaceutical polymeric coating material. A crossed cylinder matrix compaction geometry was used to simulate the geometry of two mutually indenting spherical particles. Numerical and graphical solutions delineating the relationship between contact area evolution and the prescribed loading force are presented. This particle-particle description of the contacting interface serves as a unit basis for describing the entire powder bed. The powder bed may ultimately be modeled as a collection of these particles in contact.

Powder densification. 2. Viscoelastic material properties in modeling the uniaxial compaction of powders.

A micromechanical model for predicting the densification of particulate matter under hydrostatic loading was developed to account for the time-dependent response of materials to applied loads. Viscoelastic material response used in the analysis was based upon a standard three-parameter rheological model. Compaction data under closed die conditions were collected using an Instron analyzer for different rates of applied load. Densification during the loading phase of PMMA/coMMA powder, a pharmaceutical polymeric coating material, was well predicted by the proposed algorithm, which contrasts with the prediction implied through a static indentation model. Secondary factors which affect compaction such as die-wall friction are also briefly discussed.

A comparison of elastic moduli derived from theory, microindentation, and ultrasonic testing.

PURPOSE: The objective of our work was to evaluate the elastic modulus through ultrasonic testing of poly(methyl methacrylate-co-methacrylic acid) (PMMA/coMAA), a viscoelastic polymer similar to the commercial Eudragit, to calculate this modulus, assuming a regular arrangement of interacting groups, and ultimately, assess the accuracy of microindentation as a means of evaluating elasticity in very small samples. METHODS: Knoop indentation testing was performed on cast samples using a Tukon testing apparatus. Solid density and pulse echo testing employing a damped 15 MHz transducer served to quantify the elastic moduli. Using the Hoy method of calculation for molar attraction constants, and assuming pairwise addition, the modulus was calculated and compared with typical experimental values for amorphous and crystalline polymers. RESULTS: Acoustic testing resulted in an average elastic modulus value of 5.67 +/- 0.2 GPa for this copolymer, which concurs with literature values for PMMA. Acoustically derived experimental moduli when normalized and plotted against calculated values, resulted in a relationship, E/(1 - 2v) = 17.0 (Ecoh + xc delta Hm)/V + 6.9, similar to that predicted in theory. CONCLUSIONS: Indentation contact modeling does not adequately describe the real recovery under indentation. In contrast, acoustic testing of pharmaceutical materials affords a simple, reproducible means of characterizing moduli without impairing structural integrity. Acoustically derived moduli further afford insight into the intermolecular interactions, as expressed by the interaction energy terms.

Deformation kinetics analysis of polymeric matrices.

PURPOSE: We hypothesize that if the kinetics and the mechanisms involved in tablet compression are more fully understood and quantified, the parameters which influence tablet behavior in production may be controlled. The objective of our work was to obtain two deformation kinetic parameters for the predominant barrier to deformation, the activation volume (Vact) and the activation energy (Eact) of poly (methyl methacrylate-co-methacrylic acid) (PMMA/coMAA), a viscoelastic polymer similar to the commercial Eudragit. METHODS: Stress relaxation studies were performed and monitored at varying temperatures on compacts using an instrumented Instron testing apparatus. Solid density, microindentation hardness and contact area testing served to quantify the shear stress rates. RESULTS: The Vact was found to be 64.4 +/- 4 b(3), 63.8 +/- 11 b(3) and 79.1 +/- 8 b(3) for the applied strain rates of 1, 2, and 5 mm/min. The Eact for flow was determined to be 145 +/- 7.7, 235 +/- 8.0, and 506 +/- 2.8 x 10(1) kJ/mole(-1) for the applied strain rates of 1, 2, and 5 mm/min respectively. CONCLUSIONS: The average activation energies are indicative of strain hardening effects. The activation volumes and energies obtained will serve as estimates of these state variables for input into a particle deformation model of time-dependent compaction which is underway.

Results of prostatectomy in patients following a cerebrovascular accident.

Prostatectomy was performed on 39 patients with a history of one or more cerebrovascular accidents. Only 50% had a satisfactory result from the operation and 11.7% died within 3 months of surgery. While the age of the patient, the degree of neurological deficit at the time of operation and the indication for operation had some influence on the outcome, the site of the CVA and the period of time that had elapsed since the CVA seemed to have the greatest influence.