To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Respiratory syncytial virus (RSV) can cause serious respiratory infections, second only to influenza virus. In order to know RSV's genetic changes we examined 4028 respiratory specimens from local hospital outpatients in Gyeonggi Province, South Korea over six consecutive years by real-time one-step RT–PCR; 183 patients were positive for RSV infection. To investigate the specific distribution of RSV genotypes, we performed partial sequencing of the glycoprotein gene. Of the 131 RSV-A specimens sequenced, 61 (43·3%) belonged to the ON1 genotype, 66 (46·8%) were NA1 genotype, 3 (2·1%) were GA5 genotype, and 1 (0·7%) belonged to the GA1 genotype. Of the 31 RSV-B specimens sequenced, 29 were BA9 genotype (87·9%) and 2 were BA10 genotype (6·1%). The most common clinical symptoms were fever, cough, nasal discharge, and phlegm; multiple logistic regression analysis showed that RSV-positive infection on pediatric patients was strongly associated with cough (OR = 2·8, 95% CI 1·6–5·1) and wheezing (OR = 2·8, 95% CI 1·7–4·4). The ON1 genotype was significantly associated with phlegm (OR = 11·8, 95% CI 3·8–46·7), while the NA1 genotype was associated with the pediatric patients’ gender (males, OR = 2·4, 95% CI 1·1–5·4) and presence of chills (OR = 5·1, 95% CI 1·1–27·2). RSV subgroup B was showed association with nasal obstruction (OR = 4·6, 95% CI 1·2–20·0). The majority of respiratory virus coinfections with RSV were human rhinovirus (47·2%). This study contributes to our understanding of the molecular epidemiological characteristics of RSV, which promotes the potential for improving RSV vaccines.
Radiocarbon (14C) is a radionuclide generated mainly through neutron-induced reactions in all types of nuclear reactors. Since most of the 14C released into the environment is in the form of gaseous emissions (CO2 and hydrocarbons), terrestrial plants are the primary indicators of increased 14C levels near nuclear power plants (NPPs). In 2013–2014, we collected samples of silver grasses (including common reed) and pine needles within 3 km of four South Korean NPP centers and measured 14C activities using accelerator mass spectrometry (AMS) at Seoul National University. The highest 14C activities were observed, respectively, in Wolsong>Hanul>Kori>Hanbit [220, 143, 127, and 123% modern carbon (pMC)].
Dementia is a neurodegenerative syndrome that interferes with multiple aspects of life, including cognition, daily functioning, and behavior. Despite the large heterogeneity in symptom development, these three domains are seldom studied simultaneously. This study investigates how trajectories of these domains are interrelated within individuals over time, and how they in turn are related to dementia severity and quality of life (QoL).
We used data from a longitudinal clinical cohort study, including 331 dementia patients. Cognitive status was measured using the Mini-Mental State Examination, daily functioning was measured with the disability assessment for dementia and neuropsychiatric symptoms (NPS) were scored using the neuropsychiatric inventory. We investigated the relationships in the time course of the various dementia domains using random effects multilevel models and parallel-process growth models.
Changes in cognition and daily functioning were highly correlated over time (r = 0.85, p < 0.01), as were changes in NPS and functioning (r = −0.60, p < 0.01), while changes in cognition and NPS were not (r = −0.20, p = 0.06). All three domains were strongly associated with dementia severity over time (p < 0.01). Decreased functioning and increased NPS were both associated with decreased QoL (β = 2.97, p < 0.01 and β = −2.41, p < 0.01, respectively), while cognition was not (β = 0.01, p = 0.93).
This study demonstrates the heterogeneity of dementia progression between individuals and between different dementia domains within individuals. To improve our understanding of dementia progression, future research should embrace a broader perspective encompassing multiple outcome measures along with the patient's profile, including neurological factors as well as physical, social, and psychiatric health.
We analyzed birth order differences in means and variances of height and body mass index (BMI) in monozygotic (MZ) and dizygotic (DZ) twins from infancy to old age. The data were derived from the international CODATwins database. The total number of height and BMI measures from 0.5 to 79.5 years of age was 397,466. As expected, first-born twins had greater birth weight than second-born twins. With respect to height, first-born twins were slightly taller than second-born twins in childhood. After adjusting the results for birth weight, the birth order differences decreased and were no longer statistically significant. First-born twins had greater BMI than the second-born twins over childhood and adolescence. After adjusting the results for birth weight, birth order was still associated with BMI until 12 years of age. No interaction effect between birth order and zygosity was found. Only limited evidence was found that birth order influenced variances of height or BMI. The results were similar among boys and girls and also in MZ and DZ twins. Overall, the differences in height and BMI between first- and second-born twins were modest even in early childhood, while adjustment for birth weight reduced the birth order differences but did not remove them for BMI.
The AMIGA project carries out a multiwavelength study of the largest catalogue of isolated galaxies from the Local Universe (CIG, Karachentseva 1973). Compared to any other sample —field galaxies included— and using highly strict isolation criteria (unperturbed for at least ~3 Gyr, Verdes-Montenegro et al. 2005), all the results show that these galaxies have the lowest values of the physical magnitudes expected to be enhanced by interactions. This strongly supports isolated galaxies as ideal laboratories for the study of galaxy formation and evolution. Despite CIG galaxies show the lowest HI integrated profile asymmetry level when compared to any other sample, some cases present up to 50% HI asymmetry (Espada et al. 2011b). We aim to shed light over the causes and sources of such asymmetries with our deep radiointerferometric and optical observations of CIG targets. Since major mergers are ruled out by the isolation criteria, in this work we are addressing whether minor mergers, internal processes or primordial gas accretion are responsible for such asymmetries.
We have assembled a new sample of some of the most FIR-luminous galaxies in the Universe and have imaged them in 1.1 mm dust emission and measured their redshifts 1 < z < 4 via CO emission lines using the 32-m Large Millimeter Telescope / Gran Telescopio Milimétrico (LMT/GTM). Our sample of 31 submm galaxies (SMGs), culled from the Planck and Herschel all-sky surveys, includes 14 of the 21 most luminous galaxies known, with LFIR > 1014L⊙ and SFR > 104M⊙/yr. These extreme inferred luminosities – and multiple / extended 1.1 mm images – imply that most or all are strongly gravitationally lensed, with typical magnification μ ~ 10 × . The gravitational lensing provides two significant benefits: (1) it boosts the S/N, and (2) it allows investigation of star formation and gas processes on sub-kpc scales.
It has been reported that the characteristics of a very old wood charcoal sample are different from those of modern wood charcoal according to its state of preservation (Cohen-Ofri et al. 2006; Rebollo et al. 2008). It can be assumed that these differences may lead to some difficulties when radiocarbon dating very old wood charcoal samples. To investigate this problem, we studied a carbonized trunk of Prunus pendula for. acendens tree buried in lava and found at the Hantan River lava plateau on the Korean Peninsula. The 14C date of this sample was previously measured as >30,000 BP. However, separate 14C results of its outer crust and inner wood showed a considerable difference, exceeding the estimated age differences by tree-ring counting. To study the reason for this discrepancy, optical microscopy and FTIR (Fourier transform infrared spectroscopy) were performed to examine the differences in the structural and chemical states of the samples. For reference data and to expand our understanding of very old wood charcoal, we applied the same analysis tools (AMS, FTIR, FE-SEM, EDS, and optical microscopy) to a variety of wood charcoals and original wood. From these analyses, we noticed considerable chemical changes in the outer crust sample, and this might explain the age discrepancy. Although it seems that the age difference might be due to the digestion of 14C-free CO2 from a volcanic environment, this explanation would not account for such a large value in the age difference.
A trend toward greater body size in dizygotic (DZ) than in monozygotic (MZ) twins has been suggested by some but not all studies, and this difference may also vary by age. We analyzed zygosity differences in mean values and variances of height and body mass index (BMI) among male and female twins from infancy to old age. Data were derived from an international database of 54 twin cohorts participating in the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins), and included 842,951 height and BMI measurements from twins aged 1 to 102 years. The results showed that DZ twins were consistently taller than MZ twins, with differences of up to 2.0 cm in childhood and adolescence and up to 0.9 cm in adulthood. Similarly, a greater mean BMI of up to 0.3 kg/m2 in childhood and adolescence and up to 0.2 kg/m2 in adulthood was observed in DZ twins, although the pattern was less consistent. DZ twins presented up to 1.7% greater height and 1.9% greater BMI than MZ twins; these percentage differences were largest in middle and late childhood and decreased with age in both sexes. The variance of height was similar in MZ and DZ twins at most ages. In contrast, the variance of BMI was significantly higher in DZ than in MZ twins, particularly in childhood. In conclusion, DZ twins were generally taller and had greater BMI than MZ twins, but the differences decreased with age in both sexes.
We have conducted 1.1 mm ALMA observations of a contiguous 105” × 50” or 1.5 arcmin2 window in the SXDF-UDS-CANDELS. We achieved a 5σ sensitivity of 0.28 mJy, giving a flat sensus of dusty star-forming galaxies with LIR ~6×1011L⊙ (if Tdust=40K) up to z ~ 10 thanks to the negative K-correction at this wavelength. We detected 5 brightest sources (S/N>6) and 18 low-significant sources (5>S/N>4; they may contain spurious detections, though). One of the 5 brightest ALMA sources (S1.1mm = 0.84 ± 0.09 mJy) is extremely faint in the WFC3 and VLT/HAWK-I images, demonstrating that a contiguous ALMA imaging survey uncovers a faint dust-obscured population invisible in the deep optical/near-infrared surveys. We find a possible [CII]-line emitter at z=5.955 or a low-z CO emitting galaxy within the field, allowing us to constrain the [CII] and/or CO luminosity functions across the history of the universe.
Attention deficit hyperactivity disorder (ADHD) is a common, highly heritable psychiatric disorder. Additionally, environmental factors such as perinatal stress and early adversities contribute to the occurrence and severity of ADHD. Recently, DNA methylation has emerged as a mechanism that potentially mediates gene–environmental interaction effects in the aetiology and phenomenology of psychiatric disorders. Here, we investigated whether serotonin transporter gene (SLC6A4) methylation patterns were associated with clinical characteristics and regional cortical thickness in children with ADHD.
In 102 children with ADHD (age 6–15 years), the methylation status of the SLC6A4 promoter was measured. Brain magnetic resonance imaging was obtained and ADHD symptoms were evaluated.
A higher methylation status of the SLC6A4 promoter was significantly associated with worse clinical presentations (more hyperactive-impulsive symptoms and more commission errors). Additionally, a negative correlation was observed between SLC6A4 methylation levels and cortical thickness values in the right occipito-temproral regions.
Our results suggest that the SLC6A4 methylation status may be associated with certain symptoms of ADHD, such as behavioural disinhibition, and related brain changes. Future studies that use a larger sample size and a control group are required to corroborate these results.
For over 100 years, the genetics of human anthropometric traits has attracted scientific interest. In particular, height and body mass index (BMI, calculated as kg/m2) have been under intensive genetic research. However, it is still largely unknown whether and how heritability estimates vary between human populations. Opportunities to address this question have increased recently because of the establishment of many new twin cohorts and the increasing accumulation of data in established twin cohorts. We started a new research project to analyze systematically (1) the variation of heritability estimates of height, BMI and their trajectories over the life course between birth cohorts, ethnicities and countries, and (2) to study the effects of birth-related factors, education and smoking on these anthropometric traits and whether these effects vary between twin cohorts. We identified 67 twin projects, including both monozygotic (MZ) and dizygotic (DZ) twins, using various sources. We asked for individual level data on height and weight including repeated measurements, birth related traits, background variables, education and smoking. By the end of 2014, 48 projects participated. Together, we have 893,458 height and weight measures (52% females) from 434,723 twin individuals, including 201,192 complete twin pairs (40% monozygotic, 40% same-sex dizygotic and 20% opposite-sex dizygotic) representing 22 countries. This project demonstrates that large-scale international twin studies are feasible and can promote the use of existing data for novel research purposes.
Previous studies have implicated the relationship between environmental phthalate exposure and attention deficit hyperactivity disorder (ADHD) symptoms of childhood, but no studies have been conducted in children who have a confirmed diagnosis of ADHD obtained through meticulous diagnostic testing. We aimed to determine whether phthalate metabolites in urine would be higher in children with ADHD than in those without ADHD and would correlate with symptom severity and cortical thickness in ADHD children.
A cross-sectional examination of urine phthalate metabolite concentrations was performed; scores for ADHD symptoms, externalizing problems, and continuous performance tests were obtained from 180 children with ADHD, and brain-imaging data were obtained from 115 participants. For the control group, children without ADHD (N = 438) were recruited. Correlations between phthalate metabolite concentrations and clinical measures and brain cortical thickness were investigated.
Concentrations of phthalate metabolites, particularly the di(2-ethylhexyl) phthalate (DEHP) metabolite, were significantly higher in boys with ADHD than in boys without ADHD. Concentrations of the di-n-butyl phthalate (DBP) metabolite were significantly higher in the combined or hyperactive-impulsive subtypes compared to the inattentive subtype, and the metabolite was positively correlated with the severity of externalizing symptoms. Concentrations of the DEHP metabolite were negatively correlated with cortical thickness in the right middle and superior temporal gyri.
The results of this study suggest an association between phthalate concentrations and both the diagnosis and symptom severity of ADHD. Imaging findings suggest a negative impact of phthalates on regional cortical maturation in children with ADHD.
We developed a unique preparation technique to eliminate surface damage on the c-plane of sapphire and render it atomically flat. AFM images of c-plane sapphire annealed at 1380 °C for 1hour show terrace-like features with about 0.2 μm long terraces. The GaN layers grown by MBE on annealed sapphire have [0 0 2] symmetric and [1 0 4] asymmetric full width at half maximum (FWHM) of about 60 and 132 arcsec, respectively. This compares with 408 and 600 arcsec, respectively, for GaN grown on sapphire having gone through conventional chemical cleaning.
We previously developed and validated an index of socioeconomic status (SES) termed HOUSES (housing-based index of socioeconomic status) based on real property data. In this study, we assessed whether HOUSES overcomes the absence of SES measures in medical records and is associated with risk of invasive pneumococcal disease (IPD) in children. We conducted a population-based case-control study of children in Olmsted County, MN, diagnosed with IPD (1995–2005). Each case was age- and gender-matched to two controls. HOUSES was derived using a previously reported algorithm from publicly available housing attributes (the higher HOUSES, the higher the SES). HOUSES was available for 92·3% (n = 97) and maternal education level for 43% (n = 45). HOUSES was inversely associated with risk of IPD in unmatched analysis [odds ratio (OR) 0·22, 95% confidence interval (CI) 0·05–0·89, P = 0·034], whereas maternal education was not (OR 0·77, 95% CI 0·50–1·19, P = 0·24). HOUSES may be useful for overcoming a paucity of conventional SES measures in commonly used datasets in epidemiological research.
We present new, wide, and deep images in the AzTEC/ASTE 1.1 mm continuum and the 12 CO (J = 1–0) emission toward the northern part of the Orion-A GMC. We have found evidence for interactions between molecular clouds and the external forces that may trigger star formation. Two types of possible triggers were revealed: (1) Collisions of the diffuse gas on the cloud surface, particularly at the eastern side of the OMC-2/3 region, and (2) Irradiation of UV on the pre-existing filaments and dense molecular cloud cores. Our wide-field and high-sensitivity imaging has provided the first comprehensive view of the potential sites of triggered star formation in the Orion-A GMC.
We report post-growth micro-Raman stress mapping of cracks in GaN, AlN, and AlxGa1-xN grown on (111) oriented silicon. Cracks with an average spacing of ~ 100 m are observed. These cracks are categorized into two types. The first type of crack propagates through the epilayer, and several microns deep into the substrate and is observed in all the samples investigated. The second type cracks epilayer only and is observed only in GaN. The micro-Raman stress mapping of the first type of crack shows that the epilayers are under biaxial tensile (< 0) stress and the silicon substrate is under compressive (> 0) stress far away from the cracks. The stress in the epilayers as well the substrate is found to relax from the equilibrium (far away from the cracks) value of –0.5 GPa (AlN), -0.16 GPa (GaN), -0.6 GPa (AlxGa1-xN) and 0.36 GPa (Si) as the crack position is approached. Partial relaxation is observed to occur over a range of 10 m m. At the crack position, the epilayers and the substrate are relaxed to nearly zero stress values. The stress mapping of the second type of crack reveals that the substrate is completely relaxed (stress is close o zero) far away from the cracks. At the crack position the GaN epilayer is partially relaxed from –0.2 GPa to –0.08 GPa, while the silicon substrate is seen to be under tensile stress of –0.39 GPa. The stress map of epilayers is well described by the distributed force model for both types of cracks. Furthermore, the calculated stress profiles of cracked and uncracked substrate using the above mentioned model are in excellent agreement with the experimental data.
Structural, electrical and optical properties of free-standing 200-μm thick GaN films grown by hydride vapor phase epitaxy (HVPE) have been investigated. After laser lift-off, the GaN substrates were mechanically polished on both Ga and N-sides and dry etched only on the Ga- side to obtain a smooth epi-ready surface. Hot H3PO4 chemical etching on both surfaces was used to reveal the defect sites, which appeared as hexagonal pits. The etched surfaces were then examined by atomic force microscopy. A few seconds of etching was sufficient to smooth the N- face surface and produce etch pits with a density of ≈ 1×107 cm−2. In contrast, a 50 minute etching was needed to delineate the defect sites on the Ga-face which led to a density as low as 5×105 cm−2. From plan-view and cross-sectional transmission electron microscopy (TEM) analysis, we have estimated that the dislocation density is less than about 5×106 cm−2 and ≈ 3×107 cm−2 for the Ga and N-faces respectively. The full-width at half-maximum (FWHM) of the symmetric (0002) X-ray diffraction rocking curve was 69 and 160 arcsec for the Ga and N-faces, respectively. That for the asymmetric (10 4) peak was 103 and 140 arcsec for Ga and N-faces, respectively. Hall measurements demonstrated very high mobility (1100 and 6800 cm2/V.s at 295 and 50 K, respectively) and very low concentration of donors (2.1×1016 cm−3) and acceptors (4.9×1015 cm−3). In the photoluminescence (PL) spectrum taken at 10 K, a rich excitonic structure has been observed with the highest peak attributed to the exciton bound to neutral shallow donor (BDE). The FWHM of the BDE peak was about 1.0 meV on the Ga face before and after hot chemical etching, whereas that on the N-face decreased from about 20 to 1.0 meV after chemical etching owing to the removal of the surface damage originated from the mechanical polishing.
Properties of GaN layers grown by metalorganic chemical vapor deposition (MOCVD) on c-plane of sapphire have been investigated using atomic force microscopy (AFM), wet etching for defect investigation, transmission electron microscopy (TEM), high-resolution X-ray diffraction, Hall effect measurements and low-temperature photoluminescence (PL). Tapping-mode AFM images of the as-grown samples showed atomically smooth surfaces (rms roughness ≍ 0.2 nm) consisting of terraces separated by about 3Å bi-layer steps. Hot H3PO4 chemical etching was used to produce hexagonal-shaped etch pits at the surface defect sites as revealed by AFM imaging. The obtained etch pit densities (9×108 - 2 ×109 cm−2) were in agreement with the dislocation density found by plan-view and cross-sectional TEM observations. The full-width at half-maximum (FWHM) of the X-ray diffraction rocking curve was about 4.8 and 3.9 arcmin for the symmetric (002) and asymmetric (104) directions, respectively. PL spectrum at 15 K demonstrated sharp peaks (FWHM ≍ 4 meV) in the excitonic region, which were attributed to free and bound excitons. The spectrum contained also weak PL bands with maxima at about 2.2, 2.9 and 3.27 eV, which have been attributed to three different acceptors.