2,215 research outputs found
Synthesis of High Coercivity CoreâShell Nanorods Based on Nickel and Cobalt and Their Magnetic Properties
Hybrid magnetic nanostructures with high coercivity have immense application potential in various fields. Nickel (Ni) electrodeposited inside Cobalt (Co) nanotubes (a new system named Ni @ Co nanorods) were fabricated using a two-step potentiostatic electrodeposition method. Ni @ Co nanorods were crystalline, and they have an average diameter of 150 nm and length of ~15 ÎŒm. The X-ray diffraction studies revealed the existence of two separate phases corresponding to Ni and Co. Ni @ Co nanorods exhibited a very high longitudinal coercivity. The general mobility-assisted growth mechanism proposed for the growth of one-dimensional nanostructures inside nano porous alumina during potentiostatic electrodeposition is found to be valid in this case too
Postpartum hemoperitoneum due to rupture of a blood vessel on a uterine pseudo tumor: A case report
We are reporting a case of hemoperitoneum followed by early post partum collapse due to bleeding from a ruptured vessel on the surface of an undiagnosed uterine pseudo tumor. There are literature reports of spontaneous hemoperitoneum from bleeding of superficial vessels over lyingmyomas during pregnancy but a case of rupture of a blood vessel on a uterine pseudo tumor leading to isolated hemoperitoneum in the immediatepostpartum period is a rare event. We are presenting the literature review and some aspects of the management of this case. The importance of having a high index of suspicion in cases of hemoperitoeum occurring immediately after delivery especially in a low income setting where radiologic imaging techniques like magnetic resonance imaging (MRI); which is the most sensitive diagnostic tool in cases of ruptured vessels are rare is highlighted
Human African trypanosomiasis amongst urban residents in Kinshasa: a case-control study.
BACKGROUND: Increasing numbers of human African trypanosomiasis (HAT) cases have been reported in urban residents of Kinshasa, Democratic Republic Congo since 1996. We set up a case-control study to identify risk factors for the disease. METHODS: All residents of the urban part of Kinshasa with parasitologically confirmed HAT and presenting for treatment to the city's specialized HAT clinics between 1 August, 2002 and 28 February, 2003 were included as cases. We defined the urban part as the area with contiguous habitation and a population density >5000 inhabitants per square kilometre. A digital map of the area was drawn based on a satellite image. For each case, two serologically negative controls were selected, matched on age, sex and neighbourhood. Logistic regression models were fitted to control for confounding. RESULTS: The following risk factors were independently associated with HAT: travel, commerce and cultivating fields in Bandundu, and commerce and cultivating fields in the rural part of Kinshasa. No association with activities in the city itself was found. DISCUSSION: In 2002, the emergence of HAT in urban residents of Kinshasa appears mainly linked to disease transmission in Bandundu and rural Kinshasa. We recommend to intensify control of these foci, to target HAT screening in urban residents to people with contact with these foci, to increase awareness of HAT amongst health workers in the urban health structures and to strengthen disease surveillance
Etude de lâactivitĂ© antifalcĂ©miante dâextraits de racines de Leptadenia hastata Decne. (Asclepiadacae)
Lâobjectif de cette Ă©tude est dâĂ©valuer lâactivitĂ© antifalcĂ©miante dâextraits de racines de Leptadenia hastata sur des hĂ©moglobines falciformes et dâidentifier les principes actifs Ă lâorigine de cette activitĂ©. La mĂ©thode employĂ©e Ă©tudie la rĂ©versibilitĂ© des drĂ©panocytes, en fonction du temps dâincubation des extraits par rapport aux tĂ©moins (eau physiologique, phĂ©nylalanine et arginine) sur des Ă©chantillons de sang de patients drĂ©panocytaires homozygotes. Des concentrations de 0,05; 0,5; 5 et 10 mg/ml de quatre extraits (mĂ©thanol, hexane, acĂ©tate dâĂ©thyle et mĂ©thanol rĂ©siduel) ont Ă©tĂ© mises en contact avec des drĂ©panocytes de type SS aprĂšs avoir provoquĂ© leur falciformation avec une solution Ă 2% de mĂ©tabisulfite de sodium. LâĂ©valuation a Ă©tĂ©Â effectuĂ©e toutes les 30 minutes pendant 120 minutes. Les diffĂ©rents extraits ont montrĂ© une activitĂ© dosedĂ©pendante sur la rĂ©versibilitĂ© de la falciformation des globules rouges avec plus de 80% dâinversion en 120 minutes pour lâextrait mĂ©thanolique, le plus actif. Un screening phytochimique a permis de faire une corrĂ©lation entre les flavonoĂŻdes et lâactivitĂ© antifalcĂ©miante des extraits de Leptadenia hastata.Mots clĂ©s : DrĂ©panocytose, hĂ©moglobine, activitĂ© antifalcĂ©miante, Leptadenia hastata, flavonoĂŻdes
The emergence of endothermy in the black-footed and Laysan albatrosses
Eggs with pip-holes of the black-footed ( Diomedea nigripes ) and Laysan ( Diomedea immutabilis ) albatrosses were exposed to various air temperatures in the range 20â35°C in order to detect signs of incipient endothermy in late embryos. No evidence of endothermy was found. In contrast, the O 2 consumption of most hatchlings increased in response to cooling, the O 2 consumption at an air temperature of 25° C exceeding that between 34 and 35°C by 40%. In a minority of hatchlings this response was not seen. It was suggested that endothermy may develop at some time during the 24 h after hatching.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47131/1/360_2004_Article_BF00346445.pd
Compact, directional neutron detectors capable of high-resolution nuclear recoil imaging
We report on the design, production, and performance of compact 40-cm3 Time Projection Chambers (TPCs) that detect fast neutrons by measuring the three-dimensional (3D) ionization distribution of nuclear recoils in 4He:CO2 gas at atmospheric pressure. We use these detectors to characterize the fast-neutron flux inside the Belle II detector at the SuperKEKB electronâpositron collider in Tsukuba, Japan, where the primary design constraint is a small form factor. We find that the TPCs meet or exceed all design specifications, and are capable of measuring the 3D surface shape and charge density profile of ionization clouds from nuclear recoils and charged tracks in exquisite detail. Scaled-up detectors based on the detection principle demonstrated here may be suitable for directional dark matter searches, measurements of coherent neutrinoânucleus scattering, and other experiments requiring precise detection of neutrons or nuclear recoils
Anchoring of proteins to lactic acid bacteria
The anchoring of proteins to the cell surface of lactic acid bacteria (LAB) using genetic techniques is an exciting and emerging research area that holds great promise for a wide variety of biotechnological applications. This paper reviews five different types of anchoring domains that have been explored for their efficiency in attaching hybrid proteins to the cell membrane or cell wall of LAB. The most exploited anchoring regions are those with the LPXTG box that bind the proteins in a covalent way to the cell wall. In recent years, two new modes of cell wall protein anchoring have been studied and these may provide new approaches in surface display. The important progress that is being made with cell surface display of chimaeric proteins in the areas of vaccine development and enzyme- or whole-cell immobilisation is highlighted.
Effects of habitat and livestock on nest productivity of the Asian houbara Chlamydotis macqueenii in Bukhara Province, Uzbekistan
To inform population support measures for the unsustainably hunted Asian houbara Chlamydotis macqueenii (IUCN Vulnerable) we examined potential habitat and land-use effects on nest productivity in the Kyzylkum Desert, Uzbekistan. We monitored 177 nests across different semi-arid shrub assemblages (clay-sand and salinity gradients) and a range of livestock densities (0â80 km-2). Nest success (mean 51.4%, 95% CI 42.4â60.4%) was similar across four years; predation caused 85% of those failures for which the cause was known, and only three nests were trampled by livestock. Nesting begins within a few weeks of arrival when food appears scarce, but later nests were more likely to fail owing to the emergence of a key predator, suggesting foraging conditions on wintering and passage sites may be important for nest productivity. Nest success was similar across three shrub assemblages and was unrelated to landscape rugosity, shrub frequency or livestock density, but was greater with taller mean shrub height (range 13â67 cm) within 50 m. Clutch size (mean = 3.2 eggs) and per-egg hatchability in successful nests (87.5%) did not differ with laying date, shrub assemblage or livestock density. We therefore found no evidence that livestock density reduced nest productivity across the range examined, while differing shrub assemblages appeared to offer similar habitat quality. Asian houbara appear well-adapted to a range of semi-desert habitats and tolerate moderate disturbance by pastoralism. No obvious in situ mitigation measures arise from these findings, leaving regulation and control as the key requirement to render hunting sustainable
Temporal dynamics of aquatic communities and implications for pond conservation
Conservation through the protection of particular habitats is predicated on the assumption that the conservation value of those habitats is stable. We test this assumption for ponds by investigating temporal variation in macroinvertebrate and macrophyte communities over a 10-year period in northwest England. We surveyed 51 ponds in northern England in 1995/6 and again in 2006, identifying all macrophytes (167 species) and all macroinvertebrates (221 species, excluding Diptera) to species. The alpha-diversity, beta-diversity and conservation value of these ponds were compared between surveys. We find that invertebrate species richness increased from an average of 29. 5 species to 39. 8 species between surveys. Invertebrate gamma-diversity also increased between the two surveys from 181 species to 201 species. However, this increase in diversity was accompanied by a decrease in beta-diversity. Plant alpha-, beta and gamma-diversity remained approximately constant between the two periods. However, increased proportions of grass species and a complete loss of charophytes suggests that the communities are undergoing succession. Conservation value was not correlated between sampling periods in either plants or invertebrates. This was confirmed by comparing ponds that had been disturbed with those that had no history of disturbance to demonstrate that levels of correlation between surveys were approximately equal in each group of ponds. This study has three important conservation implications: (i) a pond with high diversity or high conservation value may not remain that way and so it is unwise to base pond conservation measures upon protecting currently-speciose habitats; (ii) maximising pond gamma-diversity requires a combination of late and early succession ponds, especially for invertebrates; and (iii) invertebrate and plant communities in ponds may require different management strategies if succession occurs at varying rates in the two groups
Regulatory de novo mutations underlying intellectual disability
The genetic aetiology of a major fraction of patients with intellectual disability (ID) remains unknown. De novo mutations (DNMs) in protein-coding genes explain up to 40% of cases, but the potential role of regulatory DNMs is still poorly understood. We sequenced 63 whole genomes from 21 ID probands and their unaffected parents. In addition, we analysed 30 previously sequenced genomes from exome-negative ID probands. We found that regulatory DNMs were selectively enriched in fetal brain-specific enhancers as compared with adult brain enhancers. DNM-containing enhancers were associated with genes that show preferential expression in the prefrontal cortex. Furthermore, we identified recurrently mutated enhancer clusters that regulate genes involved in nervous system development (CSMD1, OLFM1, and POU3F3). Most of the DNMs from ID probands showed allele-specific enhancer activity when tested using luciferase assay. Using CRISPR-mediated mutation and editing of epigenomic marks, we show that DNMs at regulatory elements affect the expression of putative target genes. Our results, therefore, provide new evidence to indicate that DNMs in fetal brain-specific enhancers play an essential role in the aetiology of ID
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