Dielectric spectra of SrTiO
3
and SrTiO
3
:Mn single crystals have been studied in the frequency range of 10‒3000 cm
–1
and in the temperature range of 5–297 K using time-domain terahertz ...spectroscopy and Fourier-transform infrared spectroscopy. A comparative analysis of the experimental results made it possible to detect a significant broadening of the absorption lines corresponding to the Slater and Last phonon modes, while the parameters of the Axe mode when replacing Ti with Mn (2 at %) stay invariant. This effect is associated with an enhance in structural disorder in the cation subsystem (B-sublattice) of the SrTiO
3
crystal. It has been established that doping with Mn ions reduces the antiferrodistortive phase transition temperature by about 20 K, but hardly affects the character of the temperature dependence of the parameters of a ferroelectric soft mode at temperatures of about 60–297 K. It has been found that an additional excitation with the frequency below the frequency of the ferroelectric soft mode should be taken into account for an appropriate model description of the dispersion of the permittivity of SrTiO
3
:Mn in the terahertz frequency range. The results obtained in this work indicate that dielectric relaxation in the SrTiO
3
:Mn crystal is due to thermally activated hops of Mn atoms between displaced (noncentral) crystallographic sites; i.e., the mechanism of radiofrequency relaxation in SrTiO
3
:Mn is hopping rather than polaronic, which is also actively discussed in the literature.
A number of molecular genetic maps of the soybean Glycine max (L.) Merr. have been developed over the past 10 yr. These maps are primarily based on restriction fragment length polymorphism (RFLP) ...markers. Parental surveys have shown that most RFLP loci have only two known alleles. However, because the soybean is an ancient polyploid, RFLP probes typically hybridize and map to more than one position in the genome. Thus, the polymorphic potential of an RFLP probe is primarily a function of the frequency of the two alleles at each locus the probe detects. In contrast, simple sequence repeat (SSR) markers are single locus markers with multiple alleles. The polymorphic potential of an SSR marker is dependent on the number of alleles and their frequencies. Single locus markers provide an unambiguous means of defining linkage group homology across mapping populations. Th objective of the work reported here was to develop and map a large set of SSR markers. A total of 606 SSR loci were mapped in one or more of three populations: the USDA/Iowa State G. max x G. soja F2 population, the Univ. of Utah Minsoy x Noir 1 recombinant inbred population, and the Univ. of Nebraska Clark x Harosoy F2 population. Each SSR mapped to a single locus in the genome, with a map order that was essentially identical in all three populations. Many SSR loci were segregating in two or all three populations. Thus, it was relatively simple to align the 20+ linkage groups derived from each of the three populations into a consensus set of 20 homologous linkage groups presumed to correspond to the 20 pairs of soybean chromosomes. On the basis of in situ segregation or linkage reports in the literature all but one of the classical linkage groups can now be assigned to a corresponding molecular linkage group.
Sleep in childhood is affected by behavioral, environmental, and parental factors. We propose that these factors were altered during the COVID-19 pandemic. This study investigates sleep habit changes ...during the pandemic in 528 children 4-12 years old in the US, leveraging data from the Environmental Influences on Child Health Outcomes (ECHO) Program.
Data collection occurred in July 2019-March 2020 (pre-pandemic) and two pandemic periods: December 2020-April 2021 and May-August 2021. Qualitative interviews were performed in 38 participants.
We found no changes in sleep duration, but a shift to later sleep midpoint during the pandemic periods. There was an increase in latency at the first pandemic collection period but no increase in the frequency of bedtime resistance, and a reduced frequency of naps during the pandemic. Qualitative interviews revealed that parents prioritized routines to maintain sleep duration but were more flexible regarding timing. Children from racial/ethnic minoritized communities slept less at night, had later sleep midpoint, and napped more frequently across all collection periods, warranting in-depth investigation to examine and address root causes.
The COVID-19 pandemic significantly impacted children sleep, but parental knowledge of the importance of sleep might have played a significant protective role.
During the COVID-19 pandemic, US children changed their sleep habits, going to bed and waking up later, but their sleep duration did not change. Sleep latency was longer. Parental knowledge of sleep importance might have played a protective role. Regardless of data collection periods, children from racial/ethnic minoritized communities slept less and went to bed later. This is one of the first study on this topic in the US, including prospective pre-pandemic qualitative and quantitative data on sleep habits. Our findings highlight the pandemic long-term impact on childhood sleep. Results warrants further investigations on implications for overall childhood health.
Abstract
Single-crystalline lead substituted M-type barium hexaferrites doped with different concentrations of Al
3+
, synthesized by flux technique are investigated at terahertz and infrared ...frequencies (8-8000 cm
−1
). The spectra of reflection coefficient (R), transmission coefficient (T), complex dielectric permittivity (
ε
` and
ε
``) were obtained using terahertz time-domain, and infrared Fourier transform spectrometers over a broadband frequency range 0.24-240 THz and at temperatures 5 K-300 K. The observed absorption lines are assigned to the electronic transitions within the fine-structured ground state of Fe
2+
ions at terahertz frequencies and to optical phonon mode at far-infrared frequencies. To analyze the origin of terahertz excitations in the compounds, we provided a model that accounts for the second-order spin-orbit interactions, the triagonal distortion of the crystal field, and the selection rules of the (C
3v
) point group symmetry of tetrahedral site-position of Fe
2+
.
Glycaspis brimblecombei (Hemiptera: Aphalaridae) is an invasive, sap-sucking eucalypt pest in various parts of the world. Psyllaephagus bliteus (Hymenoptera: Encyrtidae) was first released as a ...biological control agent against this pest in California in 2000. Since then, P. bliteus has been found with its insect pest host, with no intentional introduction, in various South American, European and North African countries, and recently South Africa. Here we report on host specificity studies of P. bliteus in South Africa in order to determine potential risks to non-target hosts. Non-target test insects included the only native lerp-forming psyllid in South Africa, Retroacizzia mopani (Hemiptera: Psyllidae), as well as two free-living and one lerp-forming psyllid that are not native but also feed on Eucalyptus species. Psyllaephagus bliteus was monitored during no-choice tests for antennation, probing and oviposition behaviours towards the test insects. In addition, P. bliteus was enclosed on live plants infested with the test insects which were then monitored for offspring of P. bliteus. Retroacizzia mopani and the non-native free-living psyllids were not attacked, but P. bliteus did attack and develop on the non-native lerp psyllid, Spondyliaspis cf. plicatuloides (Hemiptera: Aphalaridae). Choice tests were then undertaken with G. brimblecombei and S. cf. plicatuloides, and G. brimblecombei was found to be the preferred host. The results indicate that the risk of P. bliteus to native insects is low, but that the host range of P. bliteus is not restricted to Glycaspis spp. and Creiis costatus (Hemiptera: Aphalaridae) as previously thought. The host range of P. bliteus may thus include other lerp-forming insects on eucalypts, especially those within the Spondyliaspidinae.
Abstract
Using methods of terahertz time-domain spectroscopy dielectric response of ceramic barium hexaferrites substituted with lead (Ba1
-x
PbxFe
12
O
19
, x = 0.00-0.30) was studied in the ...frequency range of 3-110 cm
1
and at temperatures from 5 to 300 K. Obtained spectra are presented by a rich set of lines of different nature, i.e. excitations associated with electronic transitions within the fine-structure components of Fe
2+
ions, A
2u
soft optical phonon, and ferroelectric-like soft mode. The frequency of the soft mode reveals power-law temperature variation
v
SM
∼ (T
-
T
c
)
025
, which indicates a potential phase transition atr
c
. Analysis shows that
T
c
approaches zero for the concentrations x = 0.20-0.25.
Phthalates are synthetic chemicals widely used in consumer products and have been identified to contribute to preterm birth. Existing studies have methodological limitations and potential effects of ...di-2-ethylhexyl phthalate (DEHP) replacements are poorly characterised. Attributable fractions and costs have not been quantified, limiting the ability to weigh trade-offs involved in ongoing use. We aimed to leverage a large, diverse US cohort to study associations of phthalate metabolites with birthweight and gestational age, and estimate attributable adverse birth outcomes and associated costs.
In this prospective analysis we used extant data in the US National Institutes of Health Environmental influences on Child Health Outcomes (ECHO) Program from 1998 to 2022 to study associations of 20 phthalate metabolites with gestational age at birth, birthweight, birth length, and birthweight for gestational age z-scores. We also estimated attributable adverse birth outcomes and associated costs. Mother–child dyads were included in the study if there were one or more urinary phthalate measurements during the index pregnancy; data on child's gestational age and birthweight; and singleton delivery.
We identified 5006 mother–child dyads from 13 cohorts in the ECHO Program. Phthalic acid, diisodecyl phthalate (DiDP), di-n-octyl phthalate (DnOP), and diisononyl phthalate (DiNP) were most strongly associated with gestational age, birth length, and birthweight, especially compared with DEHP or other metabolite groupings. Although DEHP was associated with preterm birth (odds ratio 1·45 95% CI 1·05–2·01), the risks per log10 increase were higher for phthalic acid (2·71 1·91–3·83), DiNP (2·25 1·67–3·00), DiDP (1·69 1·25–2·28), and DnOP (2·90 1·96–4·23). We estimated 56 595 (sensitivity analyses 24 003–120 116) phthalate-attributable preterm birth cases in 2018 with associated costs of US$3·84 billion (sensitivity analysis 1·63– 8·14 billion).
In a large, diverse sample of US births, exposure to DEHP, DiDP, DiNP, and DnOP were associated with decreased gestational age and increased risk of preterm birth, suggesting substantial opportunities for prevention. This finding suggests the adverse consequences of substitution of DEHP with chemically similar phthalates and need to regulate chemicals with similar properties as a class.
National Institutes of Health.
The increased movement of goods and pathways to transport these goods around the world, combined with the global homogenisation of cultivated areas has resulted in an increase in insect movement and ...establishment (McCullough et al. 2006; Roques et al. 2008; Aukema et al. 2010; Garnas et al. 2012). This pattern has been evident in South Africa (Giliomee 2011), including plantations of Eucalyptus where an increase in the rate of introduction of non-native insect herbivores has been reported (Wingfield et al. 2008; Garnas et al. 2012; Hurley et al. 2016). Indeed, in just three years (2012-2014), at least six insect species native to Australia and associated with Eucalyptus trees have been detected in South Africa for the first time. This short communication serves to formally report these six species, namely Glycaspis brimblecombei Moore (Hemiptera: Psyllidae), Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae), Spondyliaspis cf. plicatuloides Froggatt (Hemiptera: Psyllidae), Ophelimus maskelli Ashmead (Hymenoptera: Eulophidae), Closterocerus chamaeleon Girault (Hymenoptera: Eulophidae) and Psyllaephagus blastopsyllae Tamesse, Soufo, Tchanatame, Dzokou, Gumovsky & Coninck (Hymenoptera: Encyrtidae).
The gut microbiota influences development
and homeostasis
of the mammalian immune system, and is associated with human inflammatory
and immune diseases
as well as responses to immunotherapy
. ...Nevertheless, our understanding of how gut bacteria modulate the immune system remains limited, particularly in humans, where the difficulty of direct experimentation makes inference challenging. Here we study hundreds of hospitalized-and closely monitored-patients with cancer receiving haematopoietic cell transplantation as they recover from chemotherapy and stem-cell engraftment. This aggressive treatment causes large shifts in both circulatory immune cell and microbiota populations, enabling the relationships between the two to be studied simultaneously. Analysis of observed daily changes in circulating neutrophil, lymphocyte and monocyte counts and more than 10,000 longitudinal microbiota samples revealed consistent associations between gut bacteria and immune cell dynamics. High-resolution clinical metadata and Bayesian inference allowed us to compare the effects of bacterial genera in relation to those of immunomodulatory medications, revealing a considerable influence of the gut microbiota-together and over time-on systemic immune cell dynamics. Our analysis establishes and quantifies the link between the gut microbiota and the human immune system, with implications for microbiota-driven modulation of immunity.
High quality PbFe12O19 single crystals were grown by a solution-melt crystallization technique and characterized by synchrotron radiation diffraction structural studies, Mössbauer, Raman and infrared ...spectral measurements. In the terahertz and sub-terahertz range two absorption bands are observed, which are associated with the dynamics of structurally disordered lead and iron ions. We develop a structural model that comprises Fe2+ ions at the (1/2 × 4e) (0, 0, z) position with bipyramidal oxygen environment, and Pb ions at the (24l) (x, y, z) position with generic strongly distorted 12 vertex polyhedron of oxygen. The atomic displacement ellipsoids of the oxygen surrounding the lead ion are stretched towards the Pb ion within the plane perpendicular to the hexagonal axis. The suggested model is in full agreement with the local symmetry of the Fe2 and Pb ions and with the chemical composition of the sample determined by X-ray analysis.
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