1,368 research outputs found
Global Resources of Genetic Diversity in Peanut
Peanut or groundnut (Arachis hypogaea L.) is an annual herb, with geocarpic
fruits, and an indeterminate growth habit. It is classified as a legume in the plant
family Fabaceae. Carl Linneaus first described the cultivated species in 1753,
as A. hypogaea which was derived from the word āarachosā meaning a weed
and āhypogaeaā which means an underground chamber (Stalker and Simpson,
1995). Cultivated peanut can be classified into two subspecies, fastigiata and
hypogaea, based on the presence or absence of floral axes on the main stem.
They can be further divided into six botanical varieties (subspecies hypogaea:
var. hirsuta, and var. hypogaea; subspecies fastigiata: var. aequatoriana, var.
fastigiata, var. peruviana, and var. vulgaris) based on a range of morphological
characteristics such as growth habit, trichomes, and pod morphology. Many
intermediates exist among these botanical types, therefore, the taxonomy is not
always clear (Stalker and Simpson, 1995). In 1969, Krapovickas postulated that
the variety hypogaea was the most ancient due to its runner type habit, no floral
spikes, and branching patterns which is similar to the characteristics of the wild
Arachis species (Krapovickas, 1969)..
Twist and writhe dynamics of stiff filaments
This letter considers the dynamics of a stiff filament, in particular the
coupling of twist and bend via writhe. The time dependence of the writhe of a
filament is for a linear filament and for a curved filament. Simulations are used to study the relative
importance of crankshaft motion and tube like motion in twist dynamics.
Fuller's theorem, and its relation with the Berry phase, is reconsidered for
open filamentsComment: 7 Pages with 2 figure
Global atmospheric budget of acetaldehyde: 3-D model analysis and constraints from in-situ and satellite observations
We construct a global atmospheric budget for acetaldehyde using a 3-D model of atmospheric chemistry (GEOS-Chem), and use an ensemble of observations to evaluate present understanding of its sources and sinks. Hydrocarbon oxidation provides the largest acetaldehyde source in the model (128 Tg a<sup>&minus;1</sup>, a factor of 4 greater than the previous estimate), with alkanes, alkenes, and ethanol the main precursors. There is also a minor source from isoprene oxidation. We use an updated chemical mechanism for GEOS-Chem, and photochemical acetaldehyde yields are consistent with the Master Chemical Mechanism. We present a new approach to quantifying the acetaldehyde air-sea flux based on the global distribution of light absorption due to colored dissolved organic matter (CDOM) derived from satellite ocean color observations. The resulting net ocean emission is 57 Tg a<sup>&minus;1</sup>, the second largest global source of acetaldehyde. A key uncertainty is the acetaldehyde turnover time in the ocean mixed layer, with quantitative model evaluation over the ocean complicated by known measurement artifacts in clean air. Simulated concentrations in surface air over the ocean generally agree well with aircraft measurements, though the model tends to overestimate the vertical gradient. PAN:NO<sub>x</sub> ratios are well-simulated in the marine boundary layer, providing some support for the modeled ocean source. We introduce the Model of Emissions of Gases and Aerosols from Nature (MEGANv2.1) for acetaldehyde and ethanol and use it to quantify their net flux from living terrestrial plants. Including emissions from decaying plants the total direct acetaldehyde source from the land biosphere is 23 Tg a<sup>&minus;1</sup>. Other terrestrial acetaldehyde sources include biomass burning (3 Tg a<sup>&minus;1</sup>) and anthropogenic emissions (2 Tg a<sup>&minus;1</sup>). Simulated concentrations in the continental boundary layer are generally unbiased and capture the spatial gradients seen in observations over North America, Europe, and tropical South America. However, the model underestimates acetaldehyde levels in urban outflow, suggesting a missing source in polluted air. Ubiquitous high measured concentrations in the free troposphere are not captured by the model, and based on present understanding are not consistent with concurrent measurements of PAN and NO<sub>x</sub>: we find no compelling evidence for a widespread missing acetaldehyde source in the free troposphere. We estimate the current US source of ethanol and acetaldehyde (primary + secondary) at 1.3 Tg a<sup>&minus;1</sup> and 7.8 Tg a<sup>&minus;1</sup>, approximately 60{%} and 480% of the corresponding increases expected for a national transition from gasoline to ethanol fuel
Assessing speech, language and communication difficulties in children referred for ADHD: a qualitative evaluation of a UK child and adolescent mental health service
Background: Attention-deficit hyperactivity disorder (ADHD) is one of the most common childhood neuropsychiatric disorders and is highly comorbid with speech, language and communication difficulties (SLCDs). However, it is unclear how often SLCDs are identified in ADHD referrals in routine practice and whether there are unidentified SLCDs within this population.
Method: A thematic analysis was conducted on a random sample of case notes from 18 referrals for ADHD made to a child and adolescent mental health service (CAMHS) in London, United Kingdom. Analyses aimed to identify (a) the types of SLCDs detected during assessment, (b) at which point of the episode of care these SLCDs were suspected and (c) whether a referral or consultation was made to a speech and language therapist (SLT) for further evaluation.
Results: Out of 18 cases investigated, 15 were found to have possible SLCDs based on case notes and reports provided by external agencies. However, only four were referred by CAMHS for further assessment. It is unclear what, if any, steps other external agencies took. Themes describing types of SLCDs, comorbidities and the process of identification are discussed.
Conclusion: The analysis of this serviceās case notes revealed a range of different routes to the identification of SLCDs, and it was unclear what steps were taken as a result of assessment. A limitation is that this is just one service and the results may not generalise. However, given the similarity in practitioner training received across the country and that practitioners move from service to service, there are grounds for repeating the study in other services. We recommend a more structured approach to identifying SLCDs and recording assessment and treatment decisions made
The Viscous Nonlinear Dynamics of Twist and Writhe
Exploiting the "natural" frame of space curves, we formulate an intrinsic
dynamics of twisted elastic filaments in viscous fluids. A pair of coupled
nonlinear equations describing the temporal evolution of the filament's complex
curvature and twist density embodies the dynamic interplay of twist and writhe.
These are used to illustrate a novel nonlinear phenomenon: ``geometric
untwisting" of open filaments, whereby twisting strains relax through a
transient writhing instability without performing axial rotation. This may
explain certain experimentally observed motions of fibers of the bacterium B.
subtilis [N.H. Mendelson, et al., J. Bacteriol. 177, 7060 (1995)].Comment: 9 pages, 4 figure
Redetermination of despujolsite, Ca3Mn4+(SO4)2(OH)6Ā·3H2O
The crystal structure of despujolsite [tricalcium manganese bisĀ(sulfate) hexahydroxide triĀhydrate], the Ca/Mn member of the fleischerite group, ideally Ca3Mn4+(SO4)2(OH)6Ā·3H2O, was previously determined based on X-ray diffraction intensity data from photographs, without H-atom positions located [Gaudefroy et al. (1968 ā¶). Bull. Soc. Fr. MinĆ©ral. Crystallogr.
91, 43ā50]. The current study redetermines the structure of despujolsite from a natural specimen, with all H atoms located and with higher precision. The structure of despujolsite is characterized by layers of CaO8 polyhedra (m.. symmetry) interĀconnected by Mn(OH)6 octaĀhedra (32. symmetry) and SO4 tetraĀhedra (3.. symmetry) along [001]. The average CaāO, MnāO and SāO bond lengths are 2.489, 1.915, and 1.472ā
Ć
, respectively. There are two distinct hydrogen bonds that stabilize the structural set-up. This work represents the first description of hydrogen bonds in the fleischerite group of minerals
Which executive functioning deficits are associated with AD/HD, ODD/CD and comorbid AD/HD+ODD/CD?
Item does not contain fulltextThis study investigated (1) whether attention deficit/hyperactivity disorder (AD/HD) is associated with executive functioning (EF) deficits while controlling for oppositional defiant disorder/conduct disorder (ODD/CD), (2) whether ODD/CD is associated with EF deficits while controlling for AD/HD, and (3)~whether a combination of AD/HD and ODD/CD is associated with EF deficits (and the possibility that there is no association between EF deficits and AD/HD or ODD/CD in isolation). Subjects were 99~children ages 6ā12 years. Three putative domains of EF were investigated using well-validated tests: verbal fluency, working memory, and planning. Independent of ODD/CD, AD/HD was associated with deficits in planning and working memory, but not in verbal fluency. Only teacher rated AD/HD, but not parent rated AD/HD, significantly contributed to the prediction of EF task performance. No EF deficits were associated with ODD/CD. The presence of comorbid AD/HD accounts for the EF deficits in children with comorbid AD/HD+ODD/CD. These results suggest that EF deficits are unique to AD/HD and support the model proposed by R. A. Barkley (1997).17 p
Pathological Features of Breast Cancer seen in Northwestern Tanzania: A Nine Years Retrospective Study.
Breast cancer is more common in Western Countries compared to African populations. However in African population, it appears that the disease tends to be more aggressive and occurring at a relatively young age at the time of presentation. The aim of this study was to describe the trend of Breast Cancer in Northwestern Tanzania. This was a retrospective study which involved all cases of breast cancer diagnosed histologically at Bugando Medical Center from 2002 to 2010. Histological results and slides were retrieved from the records in the Pathology department, clinical information and demographic data for patients were retrieved from surgical wards and department of medical records. Histology slides were re-evaluated for the histological type, grade (By modified Bloom-Richardson score), and presence of necrosis and skin involvement. Data was entered and analyzed by SPSS computer software version 15. There were 328 patients histologically confirmed to have breast cancer, the mean age at diagnosis was 48.7 years (+/- 13.1). About half of the patients (52.4%) were below 46 years of age, and this group of patients had significantly higher tendency for lymph node metastasis (p = 0.012). The tumor size ranged from 1 cm to 18 cm in diameter with average (mean) of 5.5 cm (+/- 2.5), and median size of 6 cm. Size of the tumor (above 6 cm in diameter) and presence of necrosis within the tumor was significantly associated with high rate of lymph node metastasis (p = 0.000). Of all patients, 64% were at clinical stage III (specifically IIIB) and 70.4% had lymph node metastasis at the time of diagnosis. Only 4.3% of the patients were in clinical stage I at the time of diagnosis. Majority of the patients had invasive ductal carcinoma (91.5%) followed by mucinous carcinoma (5.2%), Invasive lobular carcinoma (3%) and in situ ductal carcinoma (0.3%). In all patients, 185 (56.4%) had tumor with histological grade 3. Breast cancer in this region show a trend towards relative young age at diagnosis with advanced stage at diagnosis and high rate of lymph node metastasis. Poor Referral system, lack of screening programs and natural aggressive biological behavior of tumor may contribute to advanced disease at the time of diagnosis
Clinical guidance on pharmacotherapy for the treatment of attention-deficit hyperactivity disorder (ADHD) for people with intellectual disability.
INTRODUCTION: ADHD causes significant distress and functional impairment in multiple domains of daily life. Therefore, diagnosis and treatment are important to improve the quality of life of people. The pharmacotherapy for ADHD is well established but needs systematic evaluation in Intellectual Disability (ID) populations. AREAS COVERED: This paper reviews the ADHD pharmacological treatment in people with ID using the PRISMA guidance for scoping reviews to help identify the nature and strength of evidence. EXPERT OPINION: In the last 20Ā years, seven randomized controlled trials have evaluated pharmacotherapies for ADHD in people with ID; five looking at methylphenidate. Generally, studies were underpowered; all but two had less than 25 participants. Of the two larger trials one was single blinded and therefore open to bias. Only two used a parallel-group method, the remainder were mostly short crossover trials; not ideal when measuring behavioral and psychological parameters which are long standing. The remaining evidence is made up of observational studies. Methylphenidate and atomoxetine, particularly at higher doses, have shown clear benefits in people with ID. Most people with ID tolerated ADHD medications well. Benefits were seen in behavioral and/or cognitive domains. The evidence base is limited, though promising, for dexamfetamine, clonidine, and guanfacine
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