1,248 research outputs found
Simulation of quiet-sun hard x-rays related to solar wind superhalo electrons
In this paper, we propose that the accelerated electrons in the quiet Sun could collide with the solar atmosphere to emit Hard X-rays (HXRs) via non-thermal bremsstrahlung, while some of these electrons would move upwards and escape into the interplanetary medium, to form a superhalo electron population measured in the solar wind. After considering the electron energy loss due to Coulomb collisions and the ambipolar electrostatic potential, we find that the sources of the superhalo could only occur high in the corona (at a heliocentric altitude ≳1.9 R⊙ (the mean radius of the Sun)), to remain a power-law shape of electron spectrum as observed by STEREO at 1AU near solar minimum (Wang et al., 2012). The modeled quiet-Sun HXRs related to the superhalo electrons fit well to a power-law spectrum, f∼ε−γ, with an index γ ≈ 2.0 - 2.3 (3.3 - 3.7) at 10 - 100 keV, for the warm/cold thick-target (thin-target) emissions produced by the downward-traveling (upward-traveling) accelerated electrons. These simulated quiet-Sun spectra are significantly harder than the observed spectra of most solar HXR flares. Assuming that the quiet-Sun sources cover 5% of the solar surface, the modeled thin-target HXRs are more than six orders of magnitude weaker than the RHESSI upper limit for quiet-Sun HXRs (Hannah et al., 2010). Using the thick-target model for the downward-traveling electrons, the RHESSI upper limit restricts the number of downward-traveling electrons to at most ≈3 times the number of escaping electrons. This ratio is fundamentally different from what is observed during solar flares associated with escaping electrons where the fraction of downward-traveling electrons dominates by a factor of 100 to 1000 over the escaping population
Etiology of Childhood Bilateral Sensorineural Hearing Loss in Shandong Province, China.
Objectives The purpose of this study is to ascertain the etiology of bilateral sensorineural hearing loss (SNHL) in children aged ≤ 18 years living in Shandong province. Method Data were taken from a cross-sectional study, which was conducted between 2015 and 2017. The study included children aged ≤ 18 years, recruited from special schools for children with hearing loss and from hearing rehabilitation centers in Shandong province of China. Children were screened for bilateral SNHL through audiological testing. Clinical examination, genetic testing, and structured interviews were conducted for those children who were identified as having hearing loss to identify the potential cause. Results The etiology of bilateral SNHL in our sample was genetic in 874 (39.3%), acquired in 650 (29.3%), and unknown in 697 (31.4%) children. Among children with acquired SNHL, the cause was maternal viral infection in 75 (11.5%); perinatal factors in 238 (36.6%); meningitis, measles, and mumps in 146 (22.5%); and ototoxic exposure in 117 (18%) children. Among the children with genetic SNHL, only 44 (4.9%) were identified as having syndromic hearing loss, and the remainder (95.1%) were classified as nonsyndromic hearing loss. Conclusion The findings indicated that nearly 30% of bilateral SNHL in Shandong province could be preventable through immunization, early prenatal diagnosis, proper treatment of infections, and avoidance of prescription of ototoxic drugs. This finding emphasizes the need for programs aimed at improving the health services at primary and secondary levels of health care, which will in turn prevent childhood hearing loss
Hook length biases and general linear partition inequalities
Motivated in part by hook-content formulas for certain restricted partitions
in representation theory, we consider the total number of hooks of fixed length
in odd versus distinct partitions. We show that there are more hooks of length
, respectively , in all odd partitions of than in all distinct
partitions of , and make the analogous conjecture for arbitrary hook length
. We also establish additional bias results on the number of gaps of
size respectively , in all odd versus distinct partitions of . We
conjecture similar biases and asymptotics, as well as congruences for the
number of hooks of fixed length in odd distinct partitions versus
self-conjugate partitions.
An integral component of the proof of our bias result for hooks of length
is a linear inequality involving , the number of distinct partitions of
. In this article we also establish effective linear inequalities for
in great generality, a result which is of independent interest.
Our methods are both analytic and combinatorial, and our results and
conjectures intersect the areas of representation theory, analytic number
theory, partition theory, and -series. In particular, we use a
Rademacher-type exact formula for Wright's circle method, modularity,
-series transformations, asymptotic methods, and combinatorial arguments.Comment: 36 page
ANNOTATED CHECKLIST OF CYRTANDRA (GESNERIACEAE) OF SUMATRA, INDONESIA
WANG, Q. W., BRAMLEY, G. L. C., ATKINS, H. J. & KARTONEGORO, A. 2022. Annotated checklist of Cyrtandra (Gesneriaceae) of Sumatra, Indonesia. Reinwardtia 21(2): 63‒80. — There are 53 species and three varieties of Sumatran Cyrtandra (Gesneriaceae) included in the checklist. Thirty-three lectotypes and four neotypes have been assigned, including for two excluded species. Two species are designated as incertae sedis due to a lack of type material or any associated specimens. A new name of C. jackii is proposed here to replace the illegitimate C. glabra Jack. Most of the species included in the checklist are endemic to Sumatra, with some species distributed in neighboring islands in Malesia. The next step for Cyrtandra in Sumatra is to carry out a full taxonomic revision to better understand distribution patterns and species limits and also to assign appropriate neotypes for those species still missing original material
Caesarean section for non-medical reasons at term
Background:
Caesarean section rates are progressively rising in many parts of the world. One suggested reason is increasing requests by women for caesarean section in the absence of clear medical indications, such as placenta praevia, HIV infection, contracted pelvis and, arguably, breech presentation or previous caesarean section. The reported benefits of planned caesarean section include greater safety for the baby, less pelvic floor trauma for the mother, avoidance of labour pain and convenience. The potential disadvantages, from observational studies, include increased risk of major morbidity or mortality for the mother, adverse psychological sequelae, and problems in subsequent pregnancies, including uterine scar rupture and greater risk of stillbirth and neonatal morbidity. An unbiased assessment of advantages and disadvantages would assist discussion of what has become a contentious issue in modern obstetrics.
Objectives:
To assess, from randomised trials, the effects on perinatal and maternal morbidity and mortality, and on maternal psychological morbidity, of planned caesarean delivery versus planned vaginal birth in women with no clear clinical indication for caesarean section.
Search methods:
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (April 2009).
Selection criteria:
All comparisons of intention to perform caesarean section and intention for women to give birth vaginally; random allocation to treatment and control groups; adequate allocation concealment; women at term with single fetuses with cephalic presentations and no clear medical indication for caesarean section.
Data collection and analysis:
We identified no studies that met the inclusion criteria.
Main results:
There were no included trials.
Authors' conclusions:
There is no evidence from randomised controlled trials, upon which to base any practice recommendations regarding planned caesarean section for non-medical reasons at term. In the absence of trial data, there is an urgent need for a systematic review of observational studies and a synthesis of qualitative data to better assess the short- and long-term effects of caesarean section and vaginal birth
Impact of early childhood infection on child development and school performance:a population-based study
BACKGROUND: Childhood infection might be associated with adverse child development and neurocognitive outcomes, but the results have been inconsistent.METHODS: Two population-based record-linkage cohorts of all singleton children born at term in New South Wales, Australia, from 2001 to 2014, were set up and followed up to 2019 for developmental outcome (N=276 454) and school performance (N=644 291). The primary outcome was developmentally high risk (DHR) at age 4-6 years and numeracy and reading below the national minimum standard at age 7-9 years. Cox regression was used to assess the association of childhood infection ascertained from hospital records with each outcome adjusting for maternal, birth and child characteristics, and sensitivity analyses were conducted assessing E-values and sibling analysis for discordant exposure.RESULTS: A higher proportion of children with an infection-related hospitalisation were DHR (10.9% vs 8.7%) and had numeracy (3.7% vs 2.7%) and reading results (4.3% vs 3.1%) below the national minimum standard, compared with those without infection-related hospitalisation. In the multivariable analysis, children with infection-related hospitalisation were more likely to be DHR (adjusted HR 1.12, 95% CI 1.08 to 1.15) and have numeracy (adjusted HR 1.22, 95% CI 1.18 to 1.26) and reading results (adjusted HR 1.16, 95% CI 1.12 to 1.20) below the national minimum standard. However, these results may be impacted by unmeasured confounding, based on E-values of 1.48-1.74, and minimal association with education outcome was found in the sibling analysis.CONCLUSIONS: Infection-related hospitalisation was modestly associated with adverse child development and school performance, but the association may be explained by shared familial factors, particularly in those with most socioeconomic disadvantages.</p
Long-term functional outcomes of hearing and speech rehabilitation efficacy among paediatric cochlear implant recipients in Shandong, China.
PURPOSE: To evaluate the auditory performance and speech intelligibility of 100 children with bilateral profound sensorineural hearing loss up to 3 years after cochlear implantation. METHODS: A cohort study was established consisting of 100 children who received cochlear implantation at Shandong Ear Nose and Throat Hospital from 2012 to 2015. Children were examined after 1 month, 1, 2, and 3 years of implantation to assess auditory performance and speech intelligibility using standard tools. The paired Wilcoxon signed-rank test was used to assess whether the scores obtained at different testing points differed significantly. The Mann-Whitney test was utilized to examine the between-group differences (e.g., age at implantation). RESULTS: Three years after implantation, 60% out of 100 children reached the maximal category (7) of categorical auditory performance and 37% achieved the highest category (5) of speech intelligibility rating. Significant improvements were found over time in categorical auditory performance category and speech intelligibility rating (from month 1 to year 1, p < 0.001; from year 1 to year 2, p < 0.001; and from year 2 to year 3, p < 0.001). Larger improvements in auditory outcomes and speech intelligibility were observed in children with a younger age at implantation and those who received speech therapy. CONCLUSIONS: Cochlear implantation appears to make a significant, positive contribution to the development of communication skills of young congenital and prelingually deaf children in China. These improvements continue for up to 3 years after implantation. Positive outcomes appear to be associated with earlier age at implantation and receipt of speech therapy.Implications for rehabilitationBilateral sensorineural hearing loss.Bilateral sensorineural hearing loss in children can cause delay in speech development, poor language skills and potentially disorders in psychological behaviour and social isolation.Cochlear implantation (CI) is an effective strategy that helps children with bilateral sensorineural hearing loss gain the ability to hear and continue to develop language.This study shows that the auditory performance and speech intelligibility of deaf children who speak Mandarin continued to improve up to 3 years of implantation, when follow-up ceased
Food effects in paediatric medicines development for products co-administered with food
A small amount of food is commonly used to aid administration of medicines to children to improve palatability and/or swallowability. However the impact of this co-administered food on the absorption and subsequent pharmacokinetic profile of the drug is unknown. Existing information on food effects is limited to standard protocols used to evaluate the impact of a high fat meal in an adult population using the adult medication. In the absence of a substantial body of data, there are no specific guidelines available during development of paediatric products relating to low volumes of potentially low calorie food. This paper brings together expertise to consider how the impact of co-administered food can be risk assessed during the development of a paediatric medicine. Two case studies were used to facilitate discussions and seek out commonalities in risk assessing paediatric products; these case studies used model drugs that differed in their solubility, a poorly soluble drug that demonstrated a positive food effect in adults and a highly soluble drug where a negative food effect was observed. For poorly soluble drugs risk assessments are centred upon understanding the impact of food on the in vivo solubility of the drug which requires knowledge of the composition of the food and the volumes present within the paediatric gastrointestinal tract. Further work is required to develop age appropriate in vitro and in silico models that are representative of paediatric populations. For soluble drugs it is more important to understand the mechanisms that may lead to a food effect, this may include interactions with transporters or the impact of the food composition on gastro-intestinal transit or even altered gastric motility. In silico models have the most promise for highly soluble drug products although it is essential that these models reflect the relevant mechanisms involved in potential food effects. The development of appropriate in vitro and in silico tools is limited by the lack of available clinical data that is critical to validate any tool. Further work is required to identify globally acceptable and available vehicles that should be the first option for co-administration with medicines to enable rapid and relevant risk assessment
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