13,785 research outputs found
A new record for Iran of Dolichogenidea appellator (Hym.: Braconidae: Microgastrinae), a larval endoparasitoid of diamondback moth, Plutella xylostella (Lep.: Plutellidae)
Observational notes and photographs taken in the course of rearing Euceros albitarsus Curtis
and E. pruinosus (Gravenhorst) in captivity from the egg stage are given. The bizarre biology of these
obligate hyperparasitoids involves a planidial larval stage that attaches to caterpillars or sawfly larvae,
followed by a short phase of internal parasitism of a primary parasitoid if already or subsequently present,
followed in turn by the principle growth period of external parasitism on the primary parasitoid, as shown
by Tripp (1961). Observations on aspects of this that were not illustrated by Tripp are given and, although
these transitions are not fully elucidated here, it is speculated that the number of larval instars had hitherto
been overestimated. Investigations on the behaviour and fate of the planidial phase suggest that it is best
able to transfer to primary parasitoids that are associated with the prepupal state of the lepidopteran host.
Planidia on caterpillars that are not themselves parasitised end up in the host pupa, usually occupying the
subalar cavity of the exuvial space (that is, just below the pupal cuticle at the wing cases), but do not
develop further in the absence of a primary parasitoid. A summary of some aspects of the biology of
Euceros that are not yet understood is given: the main uncertainties are the number and feeding positions
of larval instars, the timing and nature of the planidium’s transfer to the primary parasitoid, and the func-
tion of the unusual male antenn
Differentiation of dementia with Lewy bodies from Alzheimer's disease using a dopaminergic presynaptic ligand
Background: Dementia with Lewy bodies (DLB) is one of the main differential diagnoses of Alzheimer's disease (AD). Key pathological features of patients with DLB are not only the presence of cerebral cortical neuronal loss, with Lewy bodies in surviving neurones, but also loss of nigrostriatal dopaminergic neurones, similar to that of Parkinson's disease (PD). In DLB there is 40-70% loss of striatal dopamine.Objective: To determine if detection of this dopaminergic degeneration can help to distinguish DLB from AD during life.Methods: The integrity of the nigrostriatal metabolism in 27 patients with DLB, 17 with AD, 19 drug naive patients with PD, and 16 controls was assessed using a dopaminergic presynaptic ligand, I-123-labelled 2beta-carbomethoxy-3beta-(4-iodophenyl)-N-(3-fluoropropyl)nortropane (FP-CIT), and single photon emission tomography (SPET). A SPET scan was carried out with a single slice, brain dedicated tomograph (SME 810) 3.5 hours after intravenous injection of 185 MBq FP-CIT. With occipital cortex used as a radioactivity uptake reference, ratios for the caudate nucleus and the anterior and posterior putamen of both hemispheres were calculated. All scans were also rated by a simple visual method.Results: Both DLB and PD patients had significantly lower uptake of radioactivity than patients with (p<0.01) and controls (p<0.001) in the caudate nucleus and the anterior and posterior Putamen.Conclusion: FP-CIT SPET provides a means of distinguishing DLB from AD during life
Late-onset bloodstream infection and perturbed maturation of the gastrointestinal microbiota in premature infants
Late-onset bloodstream infection (LO-BSI) is a common complication of prematurity, and lack of timely diagnosis and treatment can have life-threatening consequences. We sought to identify clinical characteristics and microbial signatures in the gastrointestinal microbiota preceding diagnosis of LO-BSI in premature infants.Daily faecal samples and clinical data were collected over two years from 369 premature neonates (<32 weeks gestation). We analysed samples from 22 neonates who developed LO-BSI and 44 matched control infants. Next-generation sequencing of 16S rRNA gene regions amplified by PCR from total faecal DNA was used to characterise the microbiota of faecal samples preceding diagnosis from infants with LO-BSI and controls. Culture of selected samples was undertaken, and bacterial isolates identified using MALDI-TOF. Antibiograms from bloodstream and faecal isolates were compared to explore strain similarity.From the week prior to diagnosis, infants with LO-BSI had higher proportions of faecal aerobes/facultative anaerobes compared to controls. Risk factors for LO-BSI were identified by multivariate analysis. Enterobacteriaceal sepsis was associated with antecedent multiple lines, low birth weight and a faecal microbiota with prominent Enterobacteriaceae. Staphylococcal sepsis was associated with Staphylococcus OTU faecal over-abundance, and the number of days prior to diagnosis of mechanical ventilation and of the presence of centrally-placed lines. In 12 cases, the antibiogram of the bloodstream isolate matched that of a component of the faecal microbiota in the sample collected closest to diagnosis.The gastrointestinal tract is an important reservoir for LO-BSI organisms, pathogens translocating across the epithelial barrier. LO-BSI is associated with an aberrant microbiota, with abundant staphylococci and Enterobacteriaceae and a failure to mature towards predominance of obligate anaerobes
Molecular beam epitaxy of highly mismatched N-rich GaNSb and InNAs alloys
GaN materials alloyed with group V anions form the so-called highly mismatched alloys (HMAs). Recently, the authors succeeded in growing N-rich GaNAs and GaNBi alloys over a large composition range by plasma-assisted molecular beam epitaxy (PA-MBE). Here, they present first results on PA-MBE growth and properties of N-rich GaNSb and InNAs alloys and compare these with GaNAs and GaNBi alloys. The enhanced incorporation of As and Sb was achieved by growing the layers at extremely low growth temperatures. Although layers become amorphous for high As, Sb, and Bi content, optical absorption measurements show a progressive shift of the optical absorption edge to lower energy. The large band gap range and controllable conduction and valence band positions of these HMAs make them promising materials for efficient solar energy conversion devices
Large area radio frequency plasma for microelectronics processing
Includes bibliographical references (page 874).Radio-frequency (rf) inductively coupled planar plasma (ICP) provides a better way to generate spatially confined high density gas discharge plasmas for microelectronics processing. Commercial processing equipment using this technique is currently available, but is limited in size to 20 cm in diameter by problems with plasma uniformity and antenna dielectric window erosion. We have developed a new planar ICP antenna and dielectric window design that allows for larger dimensions (up to 50 cm in diameter) with good uniformity. The current art ICP antenna requires a thick quartz (or ceramic) plate vacuum window to separate the rf inductor and the plasma. The larger the antenna diameter the thicker the dielectric. The thick dielectric reduces inductive coupling efficiency. The large area coil and associated matching network can introduce plasma uniformity problems. Our device incorporates both the rf inductor and the dielectric window inside the vacuum chamber, allowing space for a thin layer of quartz or other dielectric material. Thus, the dielectric window design is only focused on materials for the given process chemistry to be placed between the coil and the excited plasma, rather than also including mechanical strength to hold a vacuum over a wide area. This thin dielectric layer with our newly designed planar coil coupler allows the plasma to be scaled to a 50 cm diameter while maintaining radial uniformity. In this article we report only plasma ashing results for a 20 cm planar ICP device that shows 2% nonuniformity across 15 cm wafers. The measured flux of atomic oxygen and atomic hydrogen generated by a larger planar ICP scale device is also presented
Changes in epidemiological patterns of sea lice infestation on farmed Atlantic salmon, Salmo salar L., in Scotland between 1996 and 2006
Analyses of a unique database containing sea lice records over an 11 year period provide evidence of changing infestation patterns in Scotland. The data, collected from more than 50 commercial Atlantic salmon farms, indicate that both species of sea lice commonly found in Scotland, Lepeophtheirus salmonis and Caligus elongatus, have declined on farms over the past decade. Reductions for both species have been particularly marked since 2001 when more effective veterinary medicines became available. Treatment data were also available in the database and these show a growing trend towards the use of the in feed medication emamectin benzoate (Slice), particularly in the first year of the salmon production cycle. However, this trend to wards single product use has not been sustained in 2006, the latest year for which data are available. There is some evidence of region to region variation within Scotland with the Western Isles experiencing higher levels of infestation. However, compared to the levels observed between 1996 and 2000, all regions have benefited from reduced lice infestation, with the overall pattern showing a particular reduction in the second and third quarters of the second year of production
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