The brain is a plastic organ, and so intraspecific studies that compare results obtained from wild individuals with those from common‐garden experiments are crucial for studies aiming to understand ...brain evolution. We compared volumes of brain regions between reproductively isolated populations of a neotropical fish, Poecilia mexicana, that has locally adapted to perpetual darkness (Cueva Luna Azufre), toxic hydrogen sulphide in a surface stream (El Azufre) or a combination of both stressors (Cueva del Azufre). Wild fish showed habitat‐dependent differences: enlarged telencephalic lobes and reduced optic tecta were found in fish living in darkness and sulphidic waters, in darkness without hydrogen sulphide or exposed to light and sulphide; fish from the sulphidic cave additionally showed enlarged cerebella. Comparison with common‐garden reared fish detected a general decrease in brain size throughout populations in the lab, and little of the brain size divergence between lab‐reared ecotypes that was seen in wild‐caught fish. The pronounced differences in brain region volumes between ecotypes in the wild might be interpreted within the framework of mosaic evolution; however, the outcomes of common‐garden experiments indicate a high amount of phenotypic plasticity. Our study thus highlights the importance of combining the investigation of brain size in wild populations with common‐garden experiments for answering questions of brain evolution.
The relation between vascular risk factors (VRFs) and Alzheimer's disease (AD) is important due to possible pathophysiological association.
To assess the prevalence of VRFs in biomarker-based AT(N) ...groups and the associations between VRFs, AD cerebrospinal fluid (CSF) biomarkers, brain magnetic resonance imaging (MRI), and cognition in clinical context.
We included patients from two memory clinics in University Hospital Aachen (Germany) and Maastricht University Medical Centre (The Netherlands). Subjects were older than 45 years and had available data on demographics, VRFs, CSF AD biomarkers, and MRI. We categorized individuals in normal AD biomarkers, non-AD change, and AD-continuum groups based on amyloid (A), tau (T), and neurodegeneration (N) status in CSF and MRI. Regression models were corrected for age, sex, and site.
We included 838 participants (mean age 68.7, 53.2% male, mean MMSE 24.9). The most common VRFs were smoking (60.9%), hypertension (54.6%), and dyslipidemia (37.8%). Alcohol abuse and smoking were most frequent in the non-AD-change group, and coronary heart disease and carotid artery stenosis in the AD continuum group. Higher rates of depression were found in the normal AD biomarkers group. Parietal atrophy and cortical microbleeds were specific for the AD continuum group. Carotid artery stenosis was associated with pathological Aβ42 and T-tau values, and diabetes and alcohol abuse were associated with worse medial temporal atrophy and atrial fibrillation, with worse cognition.
VRFs are common in memory clinic patients, showing differences across the AT(N) biomarker groups. This is important for prevention and individualized treatment of dementia.
Strokes have especially devastating implications if they occur early in life; however, only limited information exists on the characteristics of acute cerebrovascular disease in young adults. ...Although risk factors and manifestation of atherosclerosis are commonly associated with stroke in the elderly, recent data suggests different causes for stroke in the young. We initiated the prospective, multinational European study Stroke in Young Fabry Patients (sifap) to characterize a cohort of young stroke patients.
Overall, 5023 patients aged 18 to 55 years with the diagnosis of ischemic stroke (3396), hemorrhagic stroke (271), transient ischemic attack (1071) were enrolled in 15 European countries and 47 centers between April 2007 and January 2010 undergoing a detailed, standardized, clinical, laboratory, and radiological protocol.
Median age in the overall cohort was 46 years. Definite Fabry disease was diagnosed in 0.5% (95% confidence interval, 0.4%-0.8%; n=27) of all patients; and probable Fabry disease in additional 18 patients. Males dominated the study population (2962/59%) whereas females outnumbered men (65.3%) among the youngest patients (18-24 years). About 80.5% of the patients had a first stroke. Silent infarcts on magnetic resonance imaging were seen in 20% of patients with a first-ever stroke, and in 11.4% of patients with transient ischemic attack and no history of a previous cerebrovascular event. The most common causes of ischemic stroke were large artery atherosclerosis (18.6%) and dissection (9.9%).
Definite Fabry disease occurs in 0.5% and probable Fabry disease in further 0.4% of young stroke patients. Silent infarcts, white matter intensities, and classical risk factors were highly prevalent, emphasizing the need for new early preventive strategies. Clinical Trial Registration Information- URL: http://www.clinicaltrials.gov.Unique identifier: NCT00414583.
Numerical simulations in a tight-binding model have shown that an intersection of topologically protected one-dimensional chiral channels can function as a beam splitter for noninteracting fermions ...on a two-dimensional lattice Qiao, Jung, and MacDonald, Nano Lett. 11, 3453 (2011); Qiao et al., Phys. Rev. Lett. 112, 206601 (2014). Here we confirm this result analytically in the corresponding continuum k·p model, by solving the associated two-dimensional Dirac equation, in the presence of a “checkerboard” potential that provides a right-angled intersection between two zero-line modes. The method by which we obtain our analytical solutions is systematic and potentially generalizable to similar problems involving intersections of one-dimensional systems.
Fixed‐target serial crystallography has become an important method for the study of protein structure and dynamics at synchrotrons and X‐ray free‐electron lasers. However, sample homogeneity, ...consumption and the physical stress on samples remain major challenges for these high‐throughput experiments, which depend on high‐quality protein microcrystals. The batch crystallization procedures that are typically applied require time‐ and sample‐intensive screening and optimization. Here, a simple protein crystallization method inside the features of the HARE serial crystallography chips is reported that circumvents batch crystallization and allows the direct transfer of canonical vapor‐diffusion conditions to in‐chip crystallization. Based on conventional hanging‐drop vapor‐diffusion experiments, the crystallization solution is distributed into the wells of the HARE chip and equilibrated against a reservoir with mother liquor. Using this simple method, high‐quality microcrystals were generated with sufficient density for the structure determination of four different proteins. A new protein variant was crystallized using the protein concentrations encountered during canonical crystallization experiments, enabling structure determination from ∼55 µg of protein. Additionally, structure determination from intracellular crystals grown in insect cells cultured directly in the features of the HARE chips is demonstrated. In cellulo crystallization represents a comparatively unexplored space in crystallization, especially for proteins that are resistant to crystallization using conventional techniques, and eliminates any need for laborious protein purification. This in‐chip technique avoids harvesting the sensitive crystals or any further physical handling of the crystal‐containing cells. These proof‐of‐principle experiments indicate the potential of this method to become a simple alternative to batch crystallization approaches and also as a convenient extension to canonical crystallization screens.
The in‐chip crystallization and structure determination of four different soluble proteins and an intracellular protein using serial synchrotron crystallography is reported.
We present measurements of the auto- and cross-frequency power spectra of the cosmic infrared background (CIB) at 250, 350, and 500 mu m (1200, 860, and 600 GHz) from observations totaling ~70 deg ...sub(2) made with the SPIRE instrument aboard the Herschel Space Observatory. We measure a fractional anisotropy delta I/I = 14% + or - 4% , detecting signatures arising from the clustering of dusty star-forming galaxies in both the linear (2-halo) and nonlinear (1-halo) regimes; and that the transition from the 2- to 1-halo terms, below which power originates predominantly from multiple galaxies within dark matter halos, occurs at k sub(theta) ~ 0.10-0.12 aremin super(-1) (l ~ 2160-2380), from 250 to 500 mu m. We measure the cross-correlation power spectra between bands, finding that bands which are farthest apart are the least correlated, as well as hints of a reduction in the correlation between bands when resolved sources are more aggressively masked.
•H diffusion coefficients in Zr-alloys rolled plates were measured by neutron imaging.•H content was measured with a sensitivity of 5 wt ppm h and ∼40 µm spatial resolution.•In Zircaloy-2, a weak ...dependence of the orientation in h diffusion was found.•In Zr-2.5Nb, large differences along the rolling and normal directions were observed.•Specific measurements of h diffusion for any (α+β) Zr-alloys orientations are needed.
Zirconium alloys in nuclear power plants operate in high-pressure water at temperatures between 250 and 350 °C. Hydrogen (or deuterium) ingress due to waterside corrosion and if the solubility is exceeded H precipitates as a brittle hydride phase. Degradation mechanisms involve the accumulation of these brittle hydrides at cold spots or crack tips, as a result of H redistribution in response to thermal and stress gradients, respectively. Knowledge of H diffusion coefficients at operating temperatures is central to evaluating the rate of hydride accumulation and crack growth velocity.
We determine the diffusion coefficients of H in Zircaloy-2 and Zr-2.5%Nb rolled plates at 250 °C, 300 °C and 350 °C along the rolling and normal directions by neutron imaging experiments with sensitivity of 5 wt ppm H for a spatial resolution 0.04 mm × 2 mm. These values were evaluated from H concentration profiles measured at room temperature on specimens of dimensions 10×10×4 mm3 containing a hydride layer on one face, after annealing treatments between 60 and 600 min. This allowed the identification of a transition zone of 200–300 μm between the hydride layer and the Zr alloy material, composed by large, sparsely distributed hydrides.
In Zircaloy-2 plates, no substantial differences were observed in H diffusion along different directions or metallurgical conditions, and diffusion coefficients (0.6 ± 0.1 10−10 m2/s at 300 °C). By contrast, in hot rolled Zr-2.5%Nb plates the diffusion along the rolling direction (5.5 ± 0.5 × 10−10 m2/s at 300 °C) was much faster than along the normal direction (2.5 ± 0.7 10−10 m2/s at 300 °C), very likely due to H diffusing along the continuous network of β filaments. After a thermal treatment of 3 h at 860 °C the plate microstructure changed generating radically changed H diffusion coefficients, resulting in H diffusion being much faster along the normal direction (4.0 ± 0.5 10−10 m2/s at 300 °C) than along the rolling direction (1.4 ± 0.5 10−10 m2/s at 300 °C).
We describe the far-infrared (far-IR; rest-frame 8-1000-μm) properties of a sample of 443 Hα-selected star-forming galaxies in the Cosmic Evolution Survey (COSMOS) and Ultra Deep Survey (UDS) fields ...detected by the High-redshift Emission Line Survey (HiZELS) imaging survey. Sources are identified using narrow-band filters in combination with broad-band photometry to uniformly select Hα (and O ii if available) emitters in a narrow redshift slice at z = 1.47 ± 0.02. We use a stacking approach in Spitzer-MIPS mid-IR, Herschel-PACS/SPIRE far-IR from the PACS Evolutionary Prove (PEP) and Herschel Multi-tiered Extragalactic Survey (HerMES) and AzTEC mm-wave images to describe their typical far-IR properties. We find that HiZELS galaxies with observed Hα luminosities of L(Hα)obs 108.1-9.1 L ( 1041.7-42.7 erg s−1) have bolometric far-IR luminosities of typical luminous IR galaxies,
L. Combining the Hα and far-IR luminosities, we derive median star formation rates (SFRs) of SFRHα, FIR = 32 ± 5 M yr−1 and Hα extinctions of A
Hα = 1.0 ± 0.2 mag. Perhaps surprisingly, little difference is seen in typical HiZELS extinction levels compared to local star-forming galaxies. We confirm previous empirical stellar mass (M
*) to A
Hα relations and the little or no evolution up to z = 1.47. For HiZELS galaxies (or similar samples) we provide an empirical parametrization of the SFR as a function of rest-frame (u − z) colours and 3.6-μm photometry - a useful proxy to aid in the absence of far-IR detections in high-z galaxies. We find that the observed Hα luminosity is a dominant SFR tracer when rest-frame (u − z) colours are 0.9 mag or when Spitzer-3.6-μm photometry is fainter than 22 mag (Vega) or when stellar masses are lower than 109.7 M. We do not find any correlation between the O ii/Hα and far-IR luminosity, suggesting that this emission line ratio does not trace the extinction of the most obscured star-forming regions, especially in massive galaxies where these dominate. The luminosity-limited HiZELS sample tends to lie above of the so-called main sequence for star-forming galaxies, especially at low stellar masses, indicating high star formation efficiencies in these galaxies. This work has implications for SFR indicators and suggests that obscured star formation is linked to the assembly of stellar mass, with deeper potential wells in massive galaxies providing dense, heavily obscured environments in which stars can form rapidly.
In many animals, mate choice is important for the maintenance of reproductive isolation between species. Traits important for mate choice and behavioral isolation are predicted to be under strong ...stabilizing selection within species; however, such traits can also exhibit variation at the population level driven by neutral and adaptive evolutionary processes. Here, we describe patterns of divergence among androconial and genital chemical profiles at inter‐ and intraspecific levels in mimetic Heliconius butterflies. Most variation in chemical bouquets was found between species, but there were also quantitative differences at the population level. We found a strong correlation between interspecific chemical and genetic divergence, but this correlation varied in intraspecific comparisons. We identified “indicator” compounds characteristic of particular species that included compounds already known to elicit a behavioral response, suggesting an approach for identification of candidate compounds for future behavioral studies in novel systems. Overall, the strong signal of species identity suggests a role for these compounds in species recognition, but with additional potentially neutral variation at the population level.
In this study, we survey both inter‐ and intraspecific variation of both androconial and genital chemical profiles of male Heliconius across the Neotropics. We find that most variation in our samples is explained by species, with species‐specific compounds found consistently across a large geographic range, with additional, mainly quantitative, intraspecific variation. Overall, the strong signal of species identity suggests a role for these compounds in species recognition, but with additional neutral variation at the population level.
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