8,923 research outputs found

    Object-Oriented Paradigms for Modelling Vascular\ud Tumour Growth: a Case Study

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    Motivated by a family of related hybrid multiscale models, we have built an object-oriented framework for developing and implementing multiscale models of vascular tumour growth. The models are implemented in our framework as a case study to highlight how object-oriented programming techniques and good object-oriented design may be used effectively to develop hybrid multiscale models of vascular tumour growth. The intention is that this paper will serve as a useful reference for researchers modelling complex biological systems and that these researchers will employ some of the techniques presented herein in their own projects

    Novel use of stir bar sorptive extraction (SBSE) as a tool for isolation of oviposition site attractants for gravid Culex quinquefasciatus

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    Mosquitoes such as Culex quinquefasciatus Say (Diptera: Culicidae) are important vectors of organisms that cause disease in humans. Research into the development of effective standardized odour baits for blood-fed females (oviposition attractants), to enable entomological monitoring of vector populations, is hampered by complex protocols for extraction of physiologically active volatile chemicals from natural breeding site water samples, which have produced inconsistent results. Air entrainment and solvent extraction are technically demanding methods and are impractical for use in resource poor environments where mosquito-borne disease is most prevalent. This study reports the first use of a simple, robust extraction technique, stir bar sorptive extraction (SBSE), to extract behaviourally active small lipophilic molecules (SLMs) present in water samples collected from Cx. quinquefasciatus breeding sites in Tanzania. Extracts from a pit latrine and from a cess pool breeding site attracted more gravid Cx. quinquefasciatus in pair choice bioassays than control extracts, and coupled gas chromatography-electroantennography (GC-EAG) allowed tentative identification of 15 electrophysiologically active chemicals, including the known oviposition attractant, skatole (3-methylindole). Here, we have demonstrated, using simple pair choice bioassays in controlled laboratory conditions, that SBSE is effective for the extraction of behaviourally and electrophysiologically active semiochemicals from mosquito breeding site waters. Further research is required to confirm that SBSE is an appropriate technique for use in field surveys in the search for oviposition cues for Cx. quinquefasciatus

    Precision Doppler Shift Measurements with a Frequency Comb Calibrated Laser Heterodyne Radiometer

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    We report precision atmospheric spectroscopy of CO2CO_2 using a laser heterodyne radiometer (LHR) calibrated with an optical frequency comb. Using the comb-calibrated LHR, we record spectra of atmospheric CO2CO_2 near 1572.33 nm with a spectral resolution of 200 MHz using sunlight as a light source. The measured CO2CO_2 spectra exhibit frequency shifts by approximately 11 MHz over the course of the five-hour measurement, and we show that these shifts are caused by Doppler effects due to wind along the spectrometer line of sight. The measured frequency shifts are in excellent agreement with an atmospheric model, and we show that our measurements track the wind-induced Doppler shifts with a relative frequency precision of 100 kHz (15 cm/s), equivalent to a fractional precision of a few parts in 101010^{10}. These results demonstrate that frequency-comb-calibrated LHR enables precision velocimetry that can be of use in applications ranging from climate science to astronomy.Comment: 4 pages, 3 figure

    Self-aligned silicidation of surround gate vertical MOSFETs for low cost RF applications

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    We report for the first time a CMOS-compatible silicidation technology for surround-gate vertical MOSFETs. The technology uses a double spacer comprising a polysilicon spacer for the surround gate and a nitride spacer for silicidation and is successfully integrated with a Fillet Local OXidation (FILOX) process, which thereby delivers low overlap capacitance and high drive-current vertical devices. Silicided 80-nm vertical n-channel devices fabricated using 0.5-?m lithography are compared with nonsilicided devices. A source–drain (S/D) activation anneal of 30 s at 1100 ?C is shown to deliver a channel length of 80 nm, and the silicidation gives a 60% improvement in drive current in comparison with nonsilicided devices. The silicided devices exhibit a subthreshold slope (S) of 87 mV/dec and a drain-induced barrier lowering (DIBL) of 80 mV/V, compared with 86 mV/dec and 60 mV/V for nonsilicided devices. S-parameter measurements on the 80-nm vertical nMOS devices give an fT of 20 GHz, which is approximately two times higher than expected for comparable lateral MOSFETs fabricated using the same 0.5-?m lithography. Issues associated with silicidation down the pillar sidewall are investigated by reducing the activation anneal time to bring the silicided region closer to the p-n junction at the top of the pillar. In this situation, nonlinear transistor turn-on is observed in drain-on-top operation and dramatically degraded drive current in source-on-top operation. This behavior is interpreted using mixed-mode simulations, which show that a Schottky contact is formed around the perimeter of the pillar when the silicided contact penetrates too close to the top S/D junction down the side of the pillar

    Young children's cognitive achievement: home learning environment, language and ethnic background

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    For decades, research has shown differences in cognitive assessment scores between White and minority ethnic group(s) learners as well as differences across different minority ethnic groups. More recent data have indicated that the home learning environment and languages spoken can impact cognitive assessment and other corollary outcomes. This study uses the Millennium Cohort Study to jointly assess how minority ethnic group, home learning environment and home languages predict child cognitive assessment scores. Regression analyses were conducted using two assessment measures. The following is hypothesised: (1) cognitive achievement scores vary by minority ethnic group, (2) more home learning environment in early childhood leads to higher cognitive development scores and (3) English only in the home yields the highest cognitive scores while no English in the home yields the lowest. Findings reveal that there are differences in cognitive scores along ethnic group categories although there are also some unexpected findings. Home learning environment does not play as large a role as was predicted in raising the assessment scores overall for learners while speaking English in the home does, irrespective of ethnic background

    Clinical translation of positive metastases identified on prostate-specific membrane antigen positron emission tomography/computed tomography imaging in the management of de novo synchronous oligometastatic prostate cancer

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    Recent randomised evidence supports the diagnostic superiority of prostate-specific membrane antigen (PSMA) PET/CT, over conventional imaging, in the detection of distant occult metastasis in men with newly diagnosed high-risk prostate cancer. This may result in a rise in the detection of de novo synchronous hormone-sensitive “oligometastatic” prostate cancer. We outline the evidence supporting PSMA PET/CT imaging in primary staging. We also discuss the translation of positive areas, with a high probability of distant metastasis, into clinical therapeutic targets for metastasis-directed interventions. Finally, we highlight the role of PSMA PET/CT as an imaging biomarker. This may have future utility in disease monitoring and prediction of response to systemic, local cytoreductive and metastasis-directed interventions. Patient Summary: A new whole-body scan can accurately detect cancer deposits, in men in whom distant prostate cancer spread is suspected. This may be useful to monitor and predict response to drug therapy, treatments to the prostate and cancer deposits

    The Effect of Neonatal Leptin Antagonism in Male Rat Offspring Is Dependent upon the Interaction between Prior Maternal Nutritional Status and Post-Weaning Diet

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    Epidemiological and experimental studies report associations between overweight mothers and increased obesity risk in offspring. It is unclear whether neonatal leptin regulation mediates this association between overweight mothers and offspring obesity. We investigated the effect of neonatal treatment with a leptin antagonist (LA) on growth and metabolism in offspring of mothers fed either a control or a high fat diet. Wistar rats were fed either a control (CON) or a high fat diet (MHF) during pregnancy and lactation. Male CON and MHF neonates received either saline (S) or a rat-specific pegylated LA on days 3, 5, and 7. Offspring were weaned onto either a control or a high fat (hf) diet. At day 100, body composition, blood glucose, β-hydroxybutyrate and plasma leptin and insulin were determined. In CON and MHF offspring, LA increased neonatal bodyweights compared to saline-treated offspring and was more pronounced in MHF offspring. In the post-weaning period, neonatal LA treatment decreased hf diet-induced weight gain but only in CON offspring. LA treatment induced changes in body length, fat mass, body temperature, and bone composition. Neonatal LA treatment can therefore exert effects on growth and metabolism in adulthood but is dependent upon interactions between maternal and post-weaning nutrition

    African American Preschoolers' language, emergent literacy skills, and use of African American English: A complex relation

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    http://deepblue.lib.umich.edu/bitstream/2027.42/83315/1/African_American_Preschoolers'_language,_emergent_literacy_skills,_and_use_of_African_American_English.pd
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