977 research outputs found
Calculation of static longitudinal aerodynamic characteristics of STOL aircraft with upper surface blown flaps
An existing prediction method developed for EBF aircraft configurations was applied to USB configurations to determine its potential utility in predicting USB aerodynamic characteristics. An existing wing-flap vortex-lattice computer program was modified to handle multiple spanwise flap segments at different flap angles. A potential flow turbofan wake model developed for circular cross-section jets was used to model a rectangular cross-section jet wake by placing a number of circular jets side by side. The calculation procedure was evaluated by comparison of measured and predicted aerodynamic characteristics on a variety of USB configurations. The method is limited to the case where the flow and geometry of the configuration are symmetric about a vertical plane containing the wing root chord. Comparison of predicted and measured lift and pitching moment coefficients were made on swept wings with one and two engines per wing panel, various flap deflection angles, and a range of thrust coefficients. The results indicate satisfactory prediction of lift for flap deflections up to 55 and thrust coefficients less than 2. The applicability of the prediction procedure to USB configurations is evaluated, and specific recommendations for improvements are discussed
Gene expression in Tribolium castaneum life stages: Identifying a species-specific target for pest control applications
The red flour beetle, Tribolium castaneum, is a major agricultural pest of post-harvest products and stored grain. Control of T. castaneum in stored products and grain is primarily by fumigants and sprays, but insecticide resistance is a major problem, and new control strategies are needed. T. castaneum is a genetic model for coleopterans, and the reference genome can be used for discovery of candidate gene targets for molecular-based control, such as RNA interference. Gene targets need to be pest specific, and ideally, they are expressed at low levels for successful control. Therefore, we sequenced the transcriptome of four major life stages of T. castaneum, sorted data into groups based on high or low expression levels, and compared relative gene expression among all life stages. We narrowed our candidate gene list to a cuticle protein gene (CPG) for further analysis. We found that the CPG sequence was unique to T. castaneum and expressed only in the larval stage. RNA interference targeting CPG in newly-emerged larvae caused a significant (p < 0.05) decrease in CPG expression (1,491-fold) compared to control larvae and 64% mortality over 18 d. RNA-Seq of survivors after 18 d identified changes in the expression of other genes as well, including 52 long noncoding RNAs. Expression of three additional cuticle protein genes were increased and two chitinase genes were decreased in response to injection of CPG dsRNA. The data demonstrate that RNA-Seq can identify genes important for insect survival and thus may be used to develop novel biologically-based insect control products
Association of Early Introduction of Solids With Infant Sleep: A Secondary Analysis of a Randomized Clinical Trial.
Importance: The World Health Organization recommends exclusive breastfeeding for 6 months. However, 75% of British mothers introduce solids before 5 months and 26% report infant waking at night as influencing this decision. Objective: To determine whether early introduction of solids influences infant sleep. Design, Setting, and Participants: The Enquiring About Tolerance study was a population-based randomized clinical trial conducted from January 15, 2008, to August 31, 2015, that included 1303 exclusively breastfed 3-month-old infants from England and Wales. Clinical visits took place at St Thomas' Hospital, London, England, and the trial studied the early introduction of solids into the infant diet from age 3 months. Interventions: The early introduction group (EIG) continued to breastfeed while nonallergenic and then 6 allergenic foods were introduced. The standard introduction group (SIG) followed British infant feeding guidelines (ie, exclusive breastfeeding to around age 6 months and to avoid any food consumption during this period). Main Outcomes and Measures: Secondary analysis of an a priori secondary outcome of the effect of early food introduction on infant sleep using the standardized Brief Infant Sleep Questionnaire. Results: Of the 1303 infants who were enrolled in the Enquiring About Tolerance study, 1225 participants (94%) completed the final 3-year questionnaire (618 SIG [95%] and 607 EIG [93%]). Randomization was effective and there were no significant baseline differences between the 2 groups. Following the early introduction of solids, infants in the EIG slept significantly longer and woke significantly less frequently than infants in the SIG. Differences between the 2 groups peaked at age 6 months. At this point, in the intention-to-treat analysis infants in the EIG slept for 16.6 (95% CI, 7.8-25.4) minutes longer per night and their night waking frequency had decreased from 2.01 to 1.74 wakings per night. Most clinically important, very serious sleep problems, which were significantly associated with maternal quality of life, were reported significantly more frequently in the SIG than in the EIG (odds ratio, 1.8; 95% CI, 1.22-2.61). Conclusions and Relevance: In a randomized clinical trial, the early introduction of solids into the infant's diet was associated with longer sleep duration, less frequent waking at night, and a reduction in reported very serious sleep problems. Trial Registration: isrctn.org Identifier: ISRCTN14254740
SO(10) Cosmic Strings and Baryon Number Violation
SO(10) cosmic strings formed during the phase transition Spin(10)
SU(5) are studied. Two types of strings ---
one effectively Abelian and one non-Abelian --- are constructed and the string
solutions are calculated numerically. The non-Abelian string can catalyze
baryon number violation via the ``twisting'' of the scalar field which causes
mixing of leptons and quarks in the fermion multiplet. The non-Abelian string
is also found to have the lower energy possibly for the entire range of the
parameters in the theory. Scattering of fermions in the fields of the strings
is analyzed, and the baryon number violation cross section is calculated. The
role of the self-adjoint parameters is discussed and the values are computed.Comment: LaTex (RevTex), 36 pages, 6 figures (available upon request),
MIT-CTP#215
Study of the acoustic signature of UHE neutrino interactions in water and ice
The production of acoustic signals from the interactions of ultra-high energy
(UHE) cosmic ray neutrinos in water and ice has been studied. A new
computationally fast and efficient method of deriving the signal is presented.
This method allows the implementation of up to date parameterisations of
acoustic attenuation in sea water and ice that now includes the effects of
complex attenuation, where appropriate. The methods presented here have been
used to compute and study the properties of the acoustic signals which would be
expected from such interactions. A matrix method of parameterising the signals,
which includes the expected fluctuations, is also presented. These methods are
used to generate the expected signals that would be detected in acoustic UHE
neutrino telescopes.Comment: 21 pages and 13 figure
Cooperatives: The Governance of Patronage Dividends (A Corporate Finance Viewpoint)
Members of cooperatives are patrons and owners simultaneously, which turns out to be a consequential feature ingrained in that sort of business associations. This paper puts forward some contributions to the subject. Firstly, it defines a primary cooperative, making hence a contrast with cooperatives of cooperatives and shaping up their distinctive incremental cash-flow structure. Secondly, it focuses on some governance attributes depicted by patronage dividends in their quest for cash flows from assets. Lastly, it points out that the pursuit of growth poses a threat to primary cooperatives, entailing both governance risks and costs whenever these organizations increase in size and scope
The electric double layer has a life of its own
Using molecular dynamics simulations with recently developed importance
sampling methods, we show that the differential capacitance of a model ionic
liquid based double-layer capacitor exhibits an anomalous dependence on the
applied electrical potential. Such behavior is qualitatively incompatible with
standard mean-field theories of the electrical double layer, but is consistent
with observations made in experiment. The anomalous response results from
structural changes induced in the interfacial region of the ionic liquid as it
develops a charge density to screen the charge induced on the electrode
surface. These structural changes are strongly influenced by the out-of-plane
layering of the electrolyte and are multifaceted, including an abrupt local
ordering of the ions adsorbed in the plane of the electrode surface,
reorientation of molecular ions, and the spontaneous exchange of ions between
different layers of the electrolyte close to the electrode surface. The local
ordering exhibits signatures of a first-order phase transition, which would
indicate a singular charge-density transition in a macroscopic limit
Daily emollient during infancy for prevention of eczema: the BEEP randomised controlled trial.
BACKGROUND: Skin barrier dysfunction precedes eczema development. We tested whether daily use of emollient in the first year could prevent eczema in high-risk children. METHODS: We did a multicentre, pragmatic, parallel-group, randomised controlled trial in 12 hospitals and four primary care sites across the UK. Families were approached via antenatal or postnatal services for recruitment of term infants (at least 37 weeks' gestation) at high risk of developing eczema (ie, at least one first-degree relative with parent-reported eczema, allergic rhinitis, or asthma, diagnosed by a doctor). Term newborns with a family history of atopic disease were randomly assigned (1:1) to application of emollient daily (either Diprobase cream or DoubleBase gel) for the first year plus standard skin-care advice (emollient group) or standard skin-care advice only (control group). The randomisation schedule was created using computer-generated code (stratified by recruiting centre and number of first-degree relatives with atopic disease) and participants were assigned to groups using an internet-based randomisation system. The primary outcome was eczema at age 2 years (defined by UK working party criteria) with analysis as randomised regardless of adherence to allocation for participants with outcome data collected, and adjusting for stratification variables. This trial is registered with ISRCTN, ISRCTN21528841. Data collection for long-term follow-up is ongoing, but the trial is closed to recruitment. FINDINGS: 1394 newborns were randomly assigned to study groups between Nov 19, 2014, and Nov 18, 2016; 693 were assigned to the emollient group and 701 to the control group. Adherence in the emollient group was 88% (466 of 532) at 3 months, 82% (427 of 519) at 6 months, and 74% (375 of 506) at 12 months in those with complete questionnaire data. At age 2 years, eczema was present in 139 (23%) of 598 infants with outcome data collected in the emollient group and 150 (25%) of 612 infants in the control group (adjusted relative risk 0·95 [95% CI 0·78 to 1·16], p=0·61; adjusted risk difference -1·2% [-5·9 to 3·6]). Other eczema definitions supported the results of the primary analysis. Mean number of skin infections per child in year 1 was 0·23 (SD 0·68) in the emollient group versus 0·15 (0·46) in the control group; adjusted incidence rate ratio 1·55 (95% CI 1·15 to 2·09). INTERPRETATION: We found no evidence that daily emollient during the first year of life prevents eczema in high-risk children and some evidence to suggest an increased risk of skin infections. Our study shows that families with eczema, asthma, or allergic rhinitis should not use daily emollients to try and prevent eczema in their newborn. FUNDING: National Institute for Health Research Health Technology Assessment
- …