69 research outputs found

    Modelling eggshell maculation

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    The eggshells of many avian species are characterised by distinctive patterns of maculation, consisting of speckles, spots, blotches or streaks, the spatial-statistical properties of which vary considerably between (and often within) species. Understanding the mechanisms underlying the production of eggshell maculation would enable us to explore the costs and constraints on the evolution of maculation patterns, but as yet this area is surprisingly understudied. Here I present a simple model of eggshell maculation, which is based on the known biology of pigment deposition, and which can produce a range of realistic maculation patterns. In particular, it provides an explanation for previous observations of maculation heterogeneity and diversity, and allows testable predictions to be made regarding maculation patterns, including a possible signalling role

    Formation of a White-Light Jet within a Quadrupolar Magnetic Configuration

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    We analyze multi-wavelength and multi-viewpoint observations of a large-scale event viewed on 7 April 2011 originating from an active region complex. The activity leads to a white-light jet being formed in the outer corona. The topology and evolution of the coronal structures were imaged in high resolution using the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). In addition, large field-of-view images of the corona were obtained using the Sun Watcher using Active Pixel System detector and Image Processing (SWAP) telescope onboard the PRoject for Onboard Autonomy (PROBA2) microsatellite, providing evidence for the connectivity of the coronal structures with outer coronal features that were imaged with the Large Angle Spectrometric Coronagraph (LASCO) C2 on Solar and Heliospheric Observatory (SOHO). The data-sets reveal an Eiffel-tower type jet configuration extending into a narrow jet in the outer corona. The event starts from the growth of a dark area in the central part of the structure. The darkening was also observed in projection on the disk by the Solar TErrestrial RElations Observatory-Ahead (STEREO-A) spacecraft from a different point of view. We assume that the dark volume in the corona descends from a coronal cavity of a flux rope that moved up higher in the corona but still failed to erupt. The quadrupolar magnetic configuration corresponds to a saddle-like shape of the dark volume and provides a possibility for the plasma to escape along the open field lines into the outer corona, forming the white-light jet.Comment: 15 pages, 10 figure

    Type I and II endometrial cancers: have they different risk factors?

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    PurposeEndometrial cancers have long been divided into estrogen-dependent type I and the less common clinically aggressive estrogen-independent type II. Little is known about risk factors for type II tumors because most studies lack sufficient cases to study these much less common tumors separately. We examined whether so-called classical endometrial cancer risk factors also influence the risk of type II tumors.Patients and MethodsIndividual-level data from 10 cohort and 14 case-control studies from the Epidemiology of Endometrial Cancer Consortium were pooled. A total of 14,069 endometrial cancer cases and 35,312 controls were included. We classified endometrioid (n = 7,246), adenocarcinoma not otherwise specified (n = 4,830), and adenocarcinoma with squamous differentiation (n = 777) as type I tumors and serous (n = 508) and mixed cell (n = 346) as type II tumors.ResultsParity, oral contraceptive use, cigarette smoking, age at menarche, and diabetes were associated with type I and type II tumors to similar extents. Body mass index, however, had a greater effect on type I tumors than on type II tumors: odds ratio (OR) per 2 kg/m(2) increase was 1.20 (95% CI, 1.19 to 1.21) for type I and 1.12 (95% CI, 1.09 to 1.14) for type II tumors (P-heterogeneity < .0001). Risk factor patterns for high-grade endometrioid tumors and type II tumors were similar.ConclusionThe results of this pooled analysis suggest that the two endometrial cancer types share many common etiologic factors. The etiology of type II tumors may, therefore, not be completely estrogen independent, as previously believed. (C) 2013 by American Society of Clinical Oncolog

    Novel genetic loci associated with hippocampal volume

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    The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (rg =-0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness

    The genetic architecture of the human cerebral cortex

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    INTRODUCTION The cerebral cortex underlies our complex cognitive capabilities. Variations in human cortical surface area and thickness are associated with neurological, psychological, and behavioral traits and can be measured in vivo by magnetic resonance imaging (MRI). Studies in model organisms have identified genes that influence cortical structure, but little is known about common genetic variants that affect human cortical structure. RATIONALE To identify genetic variants associated with human cortical structure at both global and regional levels, we conducted a genome-wide association meta-analysis of brain MRI data from 51,665 individuals across 60 cohorts. We analyzed the surface area and average thickness of the whole cortex and 34 cortical regions with known functional specializations. RESULTS We identified 306 nominally genome-wide significant loci (P < 5 × 10−8) associated with cortical structure in a discovery sample of 33,992 participants of European ancestry. Of the 299 loci for which replication data were available, 241 loci influencing surface area and 14 influencing thickness remained significant after replication, with 199 loci passing multiple testing correction (P < 8.3 × 10−10; 187 influencing surface area and 12 influencing thickness). Common genetic variants explained 34% (SE = 3%) of the variation in total surface area and 26% (SE = 2%) in average thickness; surface area and thickness showed a negative genetic correlation (rG = −0.32, SE = 0.05, P = 6.5 × 10−12), which suggests that genetic influences have opposing effects on surface area and thickness. Bioinformatic analyses showed that total surface area is influenced by genetic variants that alter gene regulatory activity in neural progenitor cells during fetal development. By contrast, average thickness is influenced by active regulatory elements in adult brain samples, which may reflect processes that occur after mid-fetal development, such as myelination, branching, or pruning. When considered together, these results support the radial unit hypothesis that different developmental mechanisms promote surface area expansion and increases in thickness. To identify specific genetic influences on individual cortical regions, we controlled for global measures (total surface area or average thickness) in the regional analyses. After multiple testing correction, we identified 175 loci that influence regional surface area and 10 that influence regional thickness. Loci that affect regional surface area cluster near genes involved in the Wnt signaling pathway, which is known to influence areal identity. We observed significant positive genetic correlations and evidence of bidirectional causation of total surface area with both general cognitive functioning and educational attainment. We found additional positive genetic correlations between total surface area and Parkinson’s disease but did not find evidence of causation. Negative genetic correlations were evident between total surface area and insomnia, attention deficit hyperactivity disorder, depressive symptoms, major depressive disorder, and neuroticism. CONCLUSION This large-scale collaborative work enhances our understanding of the genetic architecture of the human cerebral cortex and its regional patterning. The highly polygenic architecture of the cortex suggests that distinct genes are involved in the development of specific cortical areas. Moreover, we find evidence that brain structure is a key phenotype along the causal pathway that leads from genetic variation to differences in general cognitive function

    Two-dimensional satellite-transition MAS NMR of quadrupolar nuclei: shifted echoes, high-spin nuclei and resolution

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    Modifications to the satellite-transition magic angle spinning (STMAS) experiment for obtaining high-resolution NMR spectra of quadrupolar nuclei are discussed. A phase-modulated `shifted-echo' STMAS experiment that yields pure absorptive lineshapes is presented and shown to be compatible with the `split-t1' technique used in multiple-quantum (MQ) MAS NMR to reduce the duration of t2 acquisition and avoid shearing the final two-dimensional spectrum. The application of STMAS to nuclei with spin greater than I=3/2 is also considered, the dispersion of isotropic shifts achieved by STMAS and MQMAS are compared, and the effects of anisotropic `cross-term' broadening mechanisms on linewidths in `isotropic' STMAS spectra are discussed

    Multiple-quantum MAS NMR of quadrupolar nuclei. Do five-, seven- and nine-quantum experiments yield higher resolution than the three-quantum experiment?

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    The question of whether or not higher-order (five-, seven- and nine-quantum) multiple-quantum magic angle spinning (MQMAS) experiments yield isotropic NMR spectra of half-integer quadrupolar nuclei with higher resolution than the basic three-quantum MAS experiment is examined. The frequency dispersion is shown theoretically to be greatly increased in higher-order MQMAS spectra, but it is argued that whether or not this translates into an increase in resolution depends upon the ratio of the homogeneous to inhomogeneous contributions to the isotropic linewidth. Experimentally, it is demonstrated using three-, five- and seven-quantum 45Sc MAS NMR and three- and five-quantum 27Al MAS NMR of crystalline samples that higher-order MQMAS experiments can yield a real and useful increase in resolution but that, owing to the presence of inhomogeneous broadening in the isotropic spectra, this increase is less than the theoretically predicted value. A number of practical issues relating to resolution in MQMAS NMR are also pointed out

    Psychological and Autonomic Correlates of Emotion Dysregulation Among Women in Substance Use Disorder Treatment

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    Emotion regulation is increasingly recognized as important for the prevention and treatment of substance use disorder (SUD). However, there is an identified lack of physiological indexes of emotion dysregulation in SUD treatment studies, critically needed to better understand the link between emotion regulation capacity (measured physiologically) and self-report health outcomes among individuals in SUD treatment. Objective: To examine the association between respiratory sinus arrhythmia (RSA) and self-report health outcomes among women in SUD treatment. Methods: This is a cross-sectional study based on baseline data from 217 women enrolled in a randomized control trial to study a mind-body intervention as an adjunct to SUD treatment. All participants were enrolled in community-based outpatient treatment. Participants were administered questionnaires to examine sample characteristics, mental health symptoms, and interoceptive awareness and mindfulness skills. RSA data was gathered as an index of emotion dysregulation. Descriptive statistics, bivariate correlations, and regression were used in the analyses. Results: Findings highlight the extensive trauma histories, low SES, and the high symptoms of distress in this sample. RSA was only significantly correlated with interoceptive awareness after controlling for age and BMI. Measures of symptomatic distress and mindfulness were not correlated with RSA. Conclusions/Importance: Results provide the first evidence of RSA as an index of interoceptive awareness in this population. The inclusion of biomarkers such as RSA in SUD clinical studies may help identify individuals that are in need of targeted treatments that include interoceptive awareness training focused on improving emotion regulation. © 2018, © 2018 Taylor & Francis Group, LLC

    Immediate Effects of Interoceptive Awareness Training Through Mindful Awareness in Body-Oriented Therapy (MABT) for Women in Substance Use Disorder Treatment

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    Sensory information gained through interoceptive awareness may play an important role in affective behavior and successful inhibition of drug use. This study examined the immediate pre-post effects of the mind-body intervention Mindful Awareness in Body-oriented Therapy (MABT) as an adjunct to women’s substance use disorder (SUD) treatment. MABT teaches interoceptive awareness skills to promote self-care and emotion regulation. Methods: Women in intensive outpatient treatment (IOP) for chemical dependency (N = 217) at 3 community clinics in the Pacific Northwest of the United States were recruited and randomly assigned to one of 3 study conditions: MABT + treatment as usual (TAU), women’s health education (WHE) +TAU (active control condition), and TAU only. At baseline and 3 months post-intervention, assessments were made of interoceptive awareness skills and mindfulness, emotion regulation (self-report and psychophysiological measures), symptomatic distress (depression and trauma-related symptoms), and substance use (days abstinent) and craving. Changes in outcomes across time were assessed using multilevel mixed-effects linear regression. Results: Findings based on an intent-to-treat approach demonstrated significant improvements in interoceptive awareness and mindfulness skills, emotion dysregulation (self-report and psychophysiology), and days abstinent for women who received MABT compared with the other study groups. Additional analyses based on participants who completed the major components of MABT (at least 75% of the intervention sessions) revealed these same improvements as well as reductions in depressive symptoms and substance craving. Conclusions: Findings that interoceptive training is associated with health outcomes for women in SUD treatment are consistent with emerging neurocognitive models that link interoception to emotion regulation and to related health outcomes, providing knowledge critical to supporting and improving SUD treatment. © 2018, © 2018 Taylor & Francis Group, LLC
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