418 research outputs found

    Reactive processing of maleic anhydride-grafted poly(butylene succinate) and the compatibilizing effect on poly(butylene succinate) nanocomposites

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    In this study, maleic anhydride-grafted poly(butylene succinate) (PBS-g-MA) was synthesized via reactive meltgrafting process using different initiator contents. The grafting efficiency was increased with the initiator content, manifested by the higher degree of grafting in PBS-g-MA. The grafting reaction was confirmed through Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. Then, PBS-g-MA was incorporated into organo-montmorillonite (OMMT) filled poly(butylene succinate) (PBS) nanocomposites as compatibilizer. Mechanical properties of PBS nanocomposites were enhanced after compatibilized with PBS-g-MA, due to the better dispersion of OMMT in PBS matrix and the improved filler-matrix interfacial interactions. This was verifiable through X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) showed that the degree of crystallinity and melting temperature increased after addition of PBS-g-MA. However, the presence of PBS-g-MA did not favor the thermal stability of the nanocomposites, as reported in the thermogravimetry (TGA)

    The Arabidopsis SAL1-PAP Pathway: A Case Study for Integrating Chloroplast Retrograde, Light and Hormonal Signaling in Modulating Plant Growth and Development?

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    Plant growth and development are dependent on chloroplast development and function. Constitutive high level accumulation of a chloroplast stress signal, 3′-phosphoadenosine-5′-phosphate (PAP), confers drought tolerance to plants, but slow downs and alters plant growth and development. PAP, a by-product of sulfur metabolism, is maintained at very low levels by the SAL1 phosphatase during vegetative growth of Arabidopsis and accumulates in rosettes during drought and excess light. Eight independent forward genetic screens in Arabidopsis identified SAL1 as the regulator of multiple phenotypes related to stress responses, hormonal signaling and/or perception. In this perspective article, we collate all the sal1 phenotypes published in the past two decades, and distill the different pathways affected. Our meta-analysis of publicly available sal1 microarray data coupled to preliminary hormonal treatment and profiling results on sal1 indicate that homeostasis and responses to multiple hormones in sal1 are altered during rosette growth, suggesting a potential connection between SAL1-PAP stress retrograde pathway and hormonal signaling. We propose the SAL1-PAP pathway as a case study for integrating chloroplast retrograde signaling, light signaling and hormonal signaling in plant growth and morphogenesis

    Epidemiological analysis of typhoid fever in Kelantan from a retrieved registry

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    Aim: Despite the endemicity of typhoid in Kelantan, epidemiological data showing typhoid association to age, sex,ethnicity and district of patients is limited. This retrospective study investigated the statistical association of thesevariables from a retrieved registry.Methodology and results: Cross-tabulation using SPSS was used to analyze 1394 cases of confirmed typhoid patientsadmitted to various hospitals in Kelantan state over a six-year period. Fourteen age groups with a five-year rangeinterval were generated. There was a significant association between typhoid infection and sex of subjects, wherebyfemales were generally more susceptible than males. Ethnicity and district of typhoid patients did not show significantassociation.Conclusion, significance and impact of study: The observation of an increased number of typhoid cases with a malepredominance in the age group 5-14 and female predominance in the 20-60 age group calls for improved hygiene,continued public health education, together with better laboratory diagnostics to identify carriers, are some measures tocontrol this disease

    Quantum Physics and Human Language

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    Human languages employ constructions that tacitly assume specific properties of the limited range of phenomena they evolved to describe. These assumed properties are true features of that limited context, but may not be general or precise properties of all the physical situations allowed by fundamental physics. In brief, human languages contain `excess baggage' that must be qualified, discarded, or otherwise reformed to give a clear account in the context of fundamental physics of even the everyday phenomena that the languages evolved to describe. The surest route to clarity is to express the constructions of human languages in the language of fundamental physical theory, not the other way around. These ideas are illustrated by an analysis of the verb `to happen' and the word `reality' in special relativity and the modern quantum mechanics of closed systems.Comment: Contribution to the festschrift for G.C. Ghirardi on his 70th Birthday, minor correction

    Urbanization and Slum Formation

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    The formation of slums need not be inevitable with rapid urbanization. Such an argument appears to be contradicted by evidence of large slum populations in a large number of developing countries and particularly in rapidly urbanizing regions like Asia. The evidence discussed suggests that city authorities faced with rapid urban development lack the capacity to cope with the diverse demands for infrastructural provision to meet economic and social needs. Not only are strategic planning and intervention major issues in agenda to manage rapid urbanization, but city governments are not effectively linking the economic development trajectory to implications for urban growth and, hence, housing needs. In the following discussion, a case study is presented in support of the argument that city governments have to first recognize and then act to establish the link that is crucial between economic development, urban growth, and housing. This is the agendum that has been largely neglected by city and national governments that have been narrowly focused on economic growth with the consequent proliferation of slum formation as a housing solution

    Vertical accuracy comparison of multi-source Digital Elevation Model (DEM) with Airborne Light Detection and Ranging (LiDAR)

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    Digital Elevation Model (DEM) is a digital representation of ground surface topography or terrain. There are many freely available DEM data with a spatial resolution of 30 m to 90 m. Nevertheless, their vertical accuracy may vary, depending on the vegetation cover and terrain characteristics. This study examined the vertical accuracy of open-access global DEMs (ALOS PALSAR, ASTER GDEM3, SRTM, TanDEM-X) and fused DEM (EarthEnvDEM90, MERIT DEM). Their performances were assessed using a Digital Terrain Model (DTM) generated using airborne LiDAR data that had an outstanding absolute vertical accuracy (mean error (ME) = 0.24 m; root mean square error (RMSEz) = 1.20 m). Height differences between the global DEMs and the LiDAR DTM were calculated and examined their performances by forested vs. non-forested, slope, and elevation classes. The results showed the MERIT DEM was superior to other DEMs in most of the testing methods. It outperformed other DEMs with an RMSEz value of 3.02 m in the forested areas, followed by ALOS PALSAR (9.29 m), EarthEnv-DEM90 (9.40 m), SRTM (9.80 m), TanDEM-X (10.41 m), and ASTER GDEM3 (12.57 m). The MERIT DEM also had the best accuracy in the higher elevation areas. Overall, the ASTER GDEM3 had the worst accuracies, with relatively large over-estimations compared to other DEMs. Despite its low spatial resolution, the MERIT DEM was the best for representing terrain elevation for applications over a large area

    40 days and 40 nights: Clinical characteristics of major trauma and orthopaedic injury comparing the incubation and lockdown phases of COVID-19 infection

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    Aims The first death in the UK caused by COVID-19 occurred on 5 March 2020. We aim to describe the clinical characteristics and outcomes of major trauma and orthopaedic patients admitted in the early COVID-19 era. Methods A prospective trauma registry was reviewed at a Level 1 Major Trauma Centre. We divided patients into Group A, 40 days prior to 5 March 2020, and into Group B, 40 days after. Results A total of 657 consecutive trauma and orthopaedic patients were identified with a mean age of 55 years (8 to 98; standard deviation (SD) 22.52) and 393 (59.8%) were males. In all, 344 (approximately 50%) of admissions were major trauma. Group A had 421 patients, decreasing to 236 patients in Group B (36%). Mechanism of injury (MOI) was commonly a fall in 351 (52.4%) patients, but road traffic accidents (RTAs) increased from 56 (13.3%) in group A to 51 (21.6%) in group B (p = 0.030). ICU admissions decreased from 26 (6.2%) in group A to 5 (2.1%) in group B. Overall, 39 patients tested positive for COVID-19 with mean age of 73 years (28 to 98; SD 17.99) and 22 (56.4%) males. Common symptoms were dyspnoea, dry cough, and pyrexia. Of these patients, 27 (69.2%) were nosocomial infections and two (5.1%) of these patients required intensive care unit (ICU) admission with 8/39 mortality (20.5%). Of the patients who died, 50% were older and had underlying comorbidities (hypertension and cardiovascular disease, dementia, arthritis). Conclusion Trauma admissions decreased in the lockdown phase with an increased incidence of RTAs. Nosocomial infection was common in 27 (69.2%) of those with COVID-19. Symptoms and comorbidities were consistent with previous reports with noted inclusion of dementia and arthritis. The mortality rate of trauma and COVID-19 was 20.5%, mainly in octogenarians, and COVID-19 surgical mortality was 15.4%

    Differential effects of prenatal psychological distress and positive mental health on offspring socioemotional development from infancy to adolescence: a meta-analysis

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    The impact of prenatal maternal mental health on offspring socioemotional development is substantial and enduring. Existing literature primarily focuses on the effects of psychological distress during pregnancy, emphasizing adverse child outcomes. Recent studies, however, highlight the unique impact of positive maternal mental health on child outcomes. To elucidate the differential associations of maternal psychological distress and positive mental health during pregnancy with child outcomes, we conducted a systematic literature search and random-effects meta-analyses on studies investigating the associations of prenatal maternal mental health with child socioemotional development. Our analyses, comprising 74 studies with 321,966 mother-child dyads across 21 countries, revealed significant associations of prenatal psychological distress with both adverse and positive child socioemotional outcomes. Notably, the effect sizes for the association of psychological distress with positive child outcomes were smaller compared to adverse outcomes. Positive prenatal mental health, on the other hand, was significantly associated with positive socioemotional outcomes but not adverse outcomes. This meta-analysis highlights the independence of negative and positive prenatal mental health constructs and their distinct relationships with child socioemotional development. The findings underscore the importance of considering the positive spectrum of maternal mental health and developmental outcomes to enhance our understanding of prenatal influences on child development. Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=335227, identifier CRD42022335227
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