2,969 research outputs found
Is the growth of the child of a smoking mother influenced by the father's prenatal exposure to tobacco? A hypothesis generating longitudinal study
OBJECTIVES: Transgenerational effects of different environmental exposures are of major interest, with rodent experiments focusing on epigenetic mechanisms. Previously, we have shown that if the study mother is a non-smoker, there is increased mean birth weight, length and body mass index (BMI) in her sons if she herself had been exposed prenatally to her mother's smoking. The aim of this study was to determine whether the prenatal smoke exposure of either parent influenced the growth of the fetus of a smoking woman, and whether any effects were dependent on the fetal sex. DESIGN: Population-based prebirth cohort study. SETTING: Avon Longitudinal Study of Parents and Children. PARTICIPANTS: Participants were residents of a geographic area with expected date of delivery between April 1991 and December 1992. Among pregnancies of mothers who smoked during pregnancy, data were available concerning maternal and paternal prenatal exposures to their own mother smoking for 3502 and 2354, respectively. PRIMARY AND SECONDARY OUTCOME MEASURES: Birth weight, length, BMI and head circumference. RESULTS: After controlling for confounders, there were no associations with birth weight, length or BMI. There was a strong adjusted association of birth head circumference among boys whose fathers had been exposed prenatally (mean difference −0.35 cm; 95% CI −0.57 to −0.14; p=0.001). There was no such association with girls (interaction p=0.006). Similar associations were found when primiparae and multiparae were analysed separately. In order to determine whether this was reflected in child development, we examined the relationships with IQ; we found that the boys born to exposed fathers had lower IQ scores on average, and that this was particularly due to the verbal component (mean difference in verbal IQ −3.65 points; 95% CI −6.60 to −0.70). CONCLUSIONS: Head size differences concerning paternal fetal exposure to smoking were unexpected and, as such, should be regarded as hypothesis generating
What drives modern protected area establishment in Australia?
Protected areas are a fundamental mechanism for ensuring the persistence of biodiversity. The strategic policy objectives set by governments for protected area land acquisition are strong determinants of biodiversity outcomes. An examination of these objectives is necessary to determine those most influential in designing protected area networks and understand why Australia's extinction rates exceed those elsewhere despite actively establishing protected areas over the past several decades. To examine spatio-temporal trends in policy objectives for protected areas, we evaluated the strategic priorities in Federal, State, and Territory policy documents across Australia between 1992 and 2019 using thematic analysis. We classified priorities into seven themes: adequacy, Indigenous and cultural values; representation of ecosystem and species types; threatened species and their habitat; social and recreational values; unique values and avoiding threatening processes. We found that the representation of ecosystem and species types was the most prevalent theme in policy documents, and the least common theme was social and recreational values. We posit several reasons for this trend and warn that emphasizing extent, in terms of area or representativeness, may diminish the effectiveness, efficiency, and impact for biodiversity outcomes. We found that policies were generally supportive of the strategic identification of particular species or communities that would quantifiably benefit from protection (referred to as avoided loss). Risked-based approaches to the establishment of protected areas are supported by modern conservation literature to enhance the protected area network's effectiveness. To maximize limited resources, we recommend that governments continue encouraging urgency to avoid species and habitat loss in their strategic priorities. This urgency should be accompanied by clear and consistent funding for on-the-ground actions which facilitate the socio-ecological outcomes that characterize modern protected area policy
Spin-Orbit Coupling, Antilocalization, and Parallel Magnetic Fields in Quantum Dots
We investigate antilocalization due to spin-orbit coupling in ballistic GaAs
quantum dots. Antilocalization that is prominent in large dots is suppressed in
small dots, as anticipated theoretically. Parallel magnetic fields suppress
both antilocalization and also, at larger fields, weak localization, consistent
with random matrix theory results once orbital coupling of the parallel field
is included. In situ control of spin-orbit coupling in dots is demonstrated as
a gate-controlled crossover from weak localization to antilocalization.Comment: related papers at http://marcuslab.harvard.ed
Inelastic semiclassical Coulomb scattering
We present a semiclassical S-matrix study of inelastic collinear
electron-hydrogen scattering. A simple way to extract all necessary information
from the deflection function alone without having to compute the stability
matrix is described. This includes the determination of the relevant Maslov
indices. Results of singlet and triplet cross sections for excitation and
ionization are reported. The different levels of approximation -- classical,
semiclassical, and uniform semiclassical -- are compared among each other and
to the full quantum result.Comment: 9 figure
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The Columbia University Scale for Psychopathology in Alzheimer's Disease
The Columbia University Scale for Psychopathology in Alzheimer's disease is a new screening instrument developed for use by clinicians or trained lay interviewers. Interrater reliability was established between a psychiatrist and a lay interviewer in 20 patients. In an independent sample of 91 outpatients with very mild to moderate probable Alzheimer's disease, caregiver informants reported that depressed mood was common (46.2%) but rarely persistent (2.2%), and that sleep disturbance occurred frequently (41.8%) but was never severe (0%). There were significant but weak associations between the presence of specific subtypes of delusions and severity of dementia. Although a variety of delusional symptoms were reported, they were frequently transient and patients often accepted the truth if corrected by the caregiver. As a result, few patients met broad or narrow operational criteria used to define delusions. Prior studies may have overestimated the prevalence of psychotic features in Alzheimer's disease by not employing standard definitional criteria. The findings also indicate that new methodology such as that employed in this instrument needs to be evaluated more widely
Gate-Controlled Spin-Orbit Quantum Interference Effects in Lateral Transport
In situ control of spin-orbit coupling in coherent transport using a clean
GaAs/AlGaAs 2DEG is realized, leading to a gate-tunable crossover from weak
localization to antilocalization. The necessary theory of 2D magnetotransport
in the presence of spin-orbit coupling beyond the diffusive approximation is
developed and used to analyze experimental data. With this theory the Rashba
contribution and linear and cubic Dresselhaus contributions to spin-orbit
coupling are separately estimated, allowing the angular dependence of
spin-orbit precession to be extracted at various gate voltages.Comment: related papers at http://marcuslab.harvard.ed
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Clinical Correlates of Alzheimer's Disease with and without Silent Radiographic Abnormalities
Objective: To determine whether patients with Alzheimer's disease (AD) who do not have historical or clinical evidence of stroke but who do have computed tomographic or magnetic resonance imaging evidence of noncortical lesions smaller than 2 cm or periventricular "caps" differ from other patients with AD. Methods: The computed tomographic or magnetic resonance imaging scans of 158 patients meeting criteria of the National Institute of Neurological Disorders and Stroke—Alzheimer's Disease and Related Disorders Association for probable AD were reviewed by one neuroradiologist. Two measures of disease severity—the Modified Mini-Mental State examination and the Blessed Dementia Rating Scale (Part I)—were subjected to two-way analysis of variance with scan type (computed tomography or magnetic resonance imaging) and lesion number as between-group factors and age and disease duration as covariates. Results: No relationship was seen between lesion number or periventricular caps and disease severity. Conclusion: In this cross-sectional analysis using these clinical measures, patients with AD who have well-defined radiographic abnormalities cannot be differentiated from patients with AD who do not have them
Classical versus Quantum Structure of the Scattering Probability Matrix. Chaotic wave-guides
The purely classical counterpart of the Scattering Probability Matrix (SPM)
of the quantum scattering matrix is defined for 2D
quantum waveguides for an arbitrary number of propagating modes . We compare
the quantum and classical structures of for a waveguide
with generic Hamiltonian chaos. It is shown that even for a moderate number of
channels, knowledge of the classical structure of the SPM allows us to predict
the global structure of the quantum one and, hence, understand important
quantum transport properties of waveguides in terms of purely classical
dynamics. It is also shown that the SPM, being an intensity measure, can give
additional dynamical information to that obtained by the Poincar\`{e} maps.Comment: 9 pages, 9 figure
Scarring Effects on Tunneling in Chaotic Double-Well Potentials
The connection between scarring and tunneling in chaotic double-well
potentials is studied in detail through the distribution of level splittings.
The mean level splitting is found to have oscillations as a function of energy,
as expected if scarring plays a role in determining the size of the splittings,
and the spacing between peaks is observed to be periodic of period
{} in action. Moreover, the size of the oscillations is directly
correlated with the strength of scarring. These results are interpreted within
the theoretical framework of Creagh and Whelan. The semiclassical limit and
finite-{} effects are discussed, and connections are made with reaction
rates and resonance widths in metastable wells.Comment: 22 pages, including 11 figure
Geometry-dependent scattering through quantum billiards: Experiment and theory
We present experimental studies of the geometry-specific quantum scattering
in microwave billiards of a given shape. We perform full quantum mechanical
scattering calculations and find an excellent agreement with the experimental
results. We also carry out the semiclassical calculations where the conductance
is given as a sum of all classical trajectories between the leads, each of them
carrying the quantum-mechanical phase. We unambiguously demonstrate that the
characteristic frequencies of the oscillations in the transmission and
reflection amplitudes are related to the length distribution of the classical
trajectories between the leads, whereas the frequencies of the probabilities
can be understood in terms of the length difference distribution in the pairs
of classical trajectories. We also discuss the effect of non-classical "ghost"
trajectories that include classically forbidden reflection off the lead mouths.Comment: 4 pages, 4 figure
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