Model of limestone weathering and damage in masonry : sedimentological and geotechnical controls in the Globigerina limestone formation (Miocene) of Malta

Five types and subtypes of stone used in construction in the Maltese Islands and three problematic stone types, mostly extracted from facies within the Oligo-Miocene Valletta Basin, are identified. Their nature and geotechnical behaviour is discussed in the context of specific use in masonry. These stone types represent end members of the variations in depositional and diagenetic environments in carbonates which control their level of physical heterogeneity, and ultimately affect the nature of damage seen in Globigerina limestone masonry. A model is presented linking the level of heterogeneity to the mode of salt weathering seen especially in ancient constructions.peer-reviewe

Syntectonic deposition of an oligo-miocene phosphorite conglomerate bed in Malta

A succession of Oligo-Miocene sediments at Sliema, Qawra and Migra Ferha includes a 1O-20cm phosphorite conglomerate bed capping the terminal hardground of the Lower Coralline Limestone Formation (Oligocene) which consists of carbonate platform sediments. The conglomerate bed always occurs in areas of significant thinning of the overlying Lower Globigerina Limestone. These palaeohighs have been linked to NNE-SSW trending lineaments. At Sliema, allochthonous phosphatised conglomerate infill NW-SE trending Neptunian dykes that dissect the platform sediments. These Oligo-Miocene syntectonic deposits were later cemented and vertically displaced by minor faulting trending NW-SE. Tectonic features at Sliema are linked to the regional N-S extensional regime and tentatively interpreted to have developed from stresses caused by displacement along the western margin of a NNE-SSW trending strike-slip fault. East of this fault, synclinal subsidence created the Valletta Basin and set conditions for current upwelling. Phosphatogenesis occurred along the basin margin swept by the prevailing westward currents. Phosphatised pebbles and ahermatypic corals were transported westward of palaeohigh margins in central and western Malta and deposited on the terminal hardground of the drowned Oligocene carbonate platform.peer-reviewe

CARBONATE FACIES, DEPOSITIONAL SEQUENCES AND TECTONOSTRATIGRAPHY OF THE PALAEOGENE MALTA PLATFORM

The break-up of Pangaea and the Late Mesozoic global sea-level rise drowned many Tethyan carbonate platforms although the resilient Malta Platform aggraded >4 km of carbonates along the North African passive margin where it was isolated from continental siliciclastics. Carbonate sedimentation was terminated by extensive Late Cretaceous to Early Paleogene depositional hiatuses, but renewed during the Oligocene, when basinward carbonate progradation began to drape over the >350 km long, cusp-shaped escarpment along the eastern margin of the isolated platform. This study sub-divides the Oligocene sediments of Malta into eight facies associations. The facies consist of carbonate grains of coral, coralline red algae and large benthic foraminifera which dominated sediments of the Late Rupelian to early Chattian, mid-Chattian and late Chattian, respectively. These successive carbonate factories produced the photozoan-heterozoan-photozoan triplet of carbonate grain associations which, when dated by benthic foraminiferal biozonation, correlates to the succession of carbonate grain associations in other Mediterranean carbonate platforms. The sedimentary triplet reflects abrupt changes in carbonate ecosystems that coincide with the last three of six surfaces that extend >80 km around Malta. The surfaces show evidence of the influence of meteoric water and pedogenic processes recognised by diagenetic features and isotopic excursions. These sequence boundaries sub-divide the succession into seven depositional sequences that reflect global third-order cyclic sea-level falls produced by glaciations with a periodicity of 1.2 Ma triggered by low-amplitude obliquity variations of the Earth’s axis combined with orbital eccentricity cycles. The periodic growth of the Antarctic ice-sheet during the Oligocene also affected Tethyan climate by shifting low latitude climate belts northwards. It is suggested that increased aridity over North Africa had reduced nutrient flux to the Tethys and favoured photozoan carbonate biota over the Malta Platform and other Tethyan carbonate platforms. The stepwise decrease in oxygen isotope ratio by the mid-Chattian reflects Antarctic deglaciation that increased both precipitation over North Africa and nutrient flux in the Tethys, favouring heterozoan ecosystems. The mid-Chattian transgressive heterozoan carbonates draped over structured bathymetry of an antecedent extensional regime that produced rotated fault-blocks. Highstand shedding of coralline red algae resulted in large clinoforms prograding into partly filled NNE trending half-graben (50 km-wide basin by lithospheric sagging over a failed Mesozoic rift. The late Chattian climatic optimum was reflected by a further decrease in the oxygen isotope ratio and aridity over North Africa and favoured a return to the photozoan association during the last phase of the Oligocene sedimentary triplet. Lepidocyclinids flourished in inner to mid-platform environments forming banks although the rate of accumulation of these hydrodynamic foraminifera did not keep up with sea-level rise. The shift to increased trophic resources by the end Oligocene terminated shallow marine carbonate sedimentation which resulted in the drowning of the Malta Platform

Multi-site genetic analysis of diffusion images and voxelwise heritability analysis : a pilot project of the ENIGMA–DTI working group

The ENIGMA (Enhancing NeuroImaging Genetics through Meta-Analysis) Consortium was set up to analyze brain measures and genotypes from multiple sites across the world to improve the power to detect genetic variants that influence the brain. Diffusion tensor imaging (DTI) yields quantitative measures sensitive to brain development and degeneration, and some common genetic variants may be associated with white matter integrity or connectivity. DTI measures, such as the fractional anisotropy (FA) of water diffusion, may be useful for identifying genetic variants that influence brain microstructure. However, genome-wide association studies (GWAS) require large populations to obtain sufficient power to detect and replicate significant effects, motivating a multi-site consortium effort. As part of an ENIGMA–DTI working group, we analyzed high-resolution FA images from multiple imaging sites across North America, Australia, and Europe, to address the challenge of harmonizing imaging data collected at multiple sites. Four hundred images of healthy adults aged 18–85 from four sites were used to create a template and corresponding skeletonized FA image as a common reference space. Using twin and pedigree samples of different ethnicities, we used our common template to evaluate the heritability of tract-derived FA measures. We show that our template is reliable for integrating multiple datasets by combining results through meta-analysis and unifying the data through exploratory mega-analyses. Our results may help prioritize regions of the FA map that are consistently influenced by additive genetic factors for future genetic discovery studies. Protocols and templates are publicly available at (http://enigma.loni.ucla.edu/ongoing/dti-working-group/)

Dex-CSDH randomised, placebo-controlled trial of dexamethasone for chronic subdural haematoma: report of the internal pilot phase.

The Dex-CSDH trial is a randomised, double-blind, placebo-controlled trial of dexamethasone for patients with a symptomatic chronic subdural haematoma. The trial commenced with an internal pilot, whose primary objective was to assess the feasibility of multi-centre recruitment. Primary outcome data collection and safety were also assessed, whilst maintaining blinding. We aimed to recruit 100 patients from United Kingdom Neurosurgical Units within 12 months. Trial participants were randomised to a 2-week course of dexamethasone or placebo in addition to receiving standard care (which could include surgery). The primary outcome measure of the trial is the modified Rankin Scale at 6 months. This pilot recruited ahead of target; 100 patients were recruited within nine months of commencement. 47% of screened patients consented to recruitment. The primary outcome measure was collected in 98% of patients. No safety concerns were raised by the independent data monitoring and ethics committee and only five patients were withdrawn from drug treatment. Pilot trial data can inform on the design and resource provision for substantive trials. This internal pilot was successful in determining recruitment feasibility. Excellent follow-up rates were achieved and exploratory outcome measures were added to increase the scientific value of the trial.NIHR HT

A vision for science education in Malta : the national curriculum framework 2011 : consultation document 2011

The current document was prepared by a working group of science and science education experts set up in November 2008 by Prof Grace Grima, Director General for Quality and Standards. The brief was to analyse the current situation of science education in Malta and to suggest a way forward that adequately addresses current as well as future national needs in the area.peer-reviewe

Translational studies in the complex role of neurotransmitter systems in anxiety and anxiety disorders

Discovery of innovative anxiolytics is severely hampering. Existing anxiolytics are developed decades ago and are still the therapeutics of choice. Moreover, lack of new drug targets forecasts a severe jeopardy in the future treatment of the huge population of CNS-diseased patients. We simply lack the knowledge on what is wrong in brains of anxious people (normal and diseased). Translational research, based on interacting clinical and preclinical research, is extremely urgent. In this endeavor, genetic and genomic approaches are part of the spectrum of contributing factors. We focus on three druggable targets: serotonin transporter, 5-HT1A, and GABAA receptors. It is still uncertain whether and how these targets are involved in normal and diseased anxiety processes. For serotonergic anxiolytics, the slow onset of action points to indirect effects leading to plasticity changes in brain systems leading to reduced anxiety. For GABAA benzodiazepine drugs, acute anxiolytic effects are found indicating primary mechanisms directly influencing anxiety processes. Close translational collaboration between fundamental academic and discovery research will lead to badly needed breakthroughs in the search for new anxiolytics.</p

Subsequent Surgery After Revision Anterior Cruciate Ligament Reconstruction: Rates and Risk Factors From a Multicenter Cohort

BACKGROUND: While revision anterior cruciate ligament reconstruction (ACLR) can be performed to restore knee stability and improve patient activity levels, outcomes after this surgery are reported to be inferior to those after primary ACLR. Further reoperations after revision ACLR can have an even more profound effect on patient satisfaction and outcomes. However, there is a current lack of information regarding the rate and risk factors for subsequent surgery after revision ACLR. PURPOSE: To report the rate of reoperations, procedures performed, and risk factors for a reoperation 2 years after revision ACLR. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A total of 1205 patients who underwent revision ACLR were enrolled in the Multicenter ACL Revision Study (MARS) between 2006 and 2011, composing the prospective cohort. Two-year questionnaire follow-up was obtained for 989 patients (82%), while telephone follow-up was obtained for 1112 patients (92%). If a patient reported having undergone subsequent surgery, operative reports detailing the subsequent procedure(s) were obtained and categorized. Multivariate regression analysis was performed to determine independent risk factors for a reoperation. RESULTS: Of the 1112 patients included in the analysis, 122 patients (11%) underwent a total of 172 subsequent procedures on the ipsilateral knee at 2-year follow-up. Of the reoperations, 27% were meniscal procedures (69% meniscectomy, 26% repair), 19% were subsequent revision ACLR, 17% were cartilage procedures (61% chondroplasty, 17% microfracture, 13% mosaicplasty), 11% were hardware removal, and 9% were procedures for arthrofibrosis. Multivariate analysis revealed that patients aged <20 years had twice the odds of patients aged 20 to 29 years to undergo a reoperation. The use of an allograft at the time of revision ACLR (odds ratio [OR], 1.79; P = .007) was a significant predictor for reoperations at 2 years, while staged revision (bone grafting of tunnels before revision ACLR) (OR, 1.93; P = .052) did not reach significance. Patients with grade 4 cartilage damage seen during revision ACLR were 78% less likely to undergo subsequent operations within 2 years. Sex, body mass index, smoking history, Marx activity score, technique for femoral tunnel placement, and meniscal tearing or meniscal treatment at the time of revision ACLR showed no significant effect on the reoperation rate. CONCLUSION: There was a significant reoperation rate after revision ACLR at 2 years (11%), with meniscal procedures most commonly involved. Independent risk factors for subsequent surgery on the ipsilateral knee included age <20 years and the use of allograft tissue at the time of revision ACLR

Impact of early enteral versus parenteral nutrition on mortality in patients requiring mechanical ventilation and catecholamines: study protocol for a randomized controlled trial (NUTRIREA-2)

BACKGROUND: Nutritional support is crucial to the management of patients receiving invasive mechanical ventilation (IMV) and the most commonly prescribed treatment in intensive care units (ICUs). International guidelines consistently indicate that enteral nutrition (EN) should be preferred over parenteral nutrition (PN) whenever possible and started as early as possible. However, no adequately designed study has evaluated whether a specific nutritional modality is associated with decreased mortality. The primary goal of this trial is to assess the hypothesis that early first-line EN, as compared to early first-line PN, decreases day 28 all-cause mortality in patients receiving IMV and vasoactive drugs for shock. METHODS/DESIGN: The NUTRIREA-2 study is a multicenter, open-label, parallel-group, randomized controlled trial comparing early PN versus early EN in critically ill patients requiring IMV for an expected duration of at least 48 hours, combined with vasoactive drugs, for shock. Patients will be allocated at random to first-line PN for at least 72 hours or to first-line EN. In both groups, nutritional support will be started within 24 hours after IMV initiation. Calorie targets will be 20 to 25 kcal/kg/day during the first week, then 25 to 30 kcal/kg/day thereafter. Patients receiving PN may be switched to EN after at least 72 hours in the event of shock resolution (no vasoactive drugs for 24 consecutive hours and arterial lactic acid level below 2 mmol/L). On day 7, all patients receiving PN and having no contraindications to EN will be switched to EN. In both groups, supplemental PN may be added to EN after day 7 in patients with persistent intolerance to EN and inadequate calorie intake. We plan to recruit 2,854 patients at 44 participating ICUs. DISCUSSION: The NUTRIREA-2 study is the first large randomized controlled trial designed to assess the hypothesis that early EN improves survival compared to early PN in ICU patients. Enrollment started on 22 March 2013 and is expected to end in November 2015. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01802099 (registered 27 February 2013)