The Earth-Moon system has unique chemical and isotopic signatures compared with other planetary bodies; any successful model for the origin of this system therefore has to satisfy these chemical and ...isotopic constraints. The Moon is substantially depleted in volatile elements such as potassium compared with the Earth and the bulk solar composition, and it has long been thought to be the result of a catastrophic Moon-forming giant impact event. Volatile-element-depleted bodies such as the Moon were expected to be enriched in heavy potassium isotopes during the loss of volatiles; however such enrichment was never found. Here we report new high-precision potassium isotope data for the Earth, the Moon and chondritic meteorites. We found that the lunar rocks are significantly (>2σ) enriched in the heavy isotopes of potassium compared to the Earth and chondrites (by around 0.4 parts per thousand). The enrichment of the heavy isotope of potassium in lunar rocks compared with those of the Earth and chondrites can be best explained as the result of the incomplete condensation of a bulk silicate Earth vapour at an ambient pressure that is higher than 10 bar. We used these coupled constraints of the chemical loss and isotopic fractionation of K to compare two recent dynamic models that were used to explain the identical non-mass-dependent isotope composition of the Earth and the Moon. Our K isotope result is inconsistent with the low-energy disk equilibration model, but supports the high-energy, high-angular-momentum giant impact model for the origin of the Moon. High-precision potassium isotope data can also be used as a 'palaeo-barometer' to reveal the physical conditions during the Moon-forming event.
ABSTRACT Several small dense exoplanets are now known, inviting comparisons to Earth and Venus. Such comparisons require translating their masses and sizes to composition models of evolved ...multi-layer interior planets. Such theoretical models rely on our understanding of the Earth's interior, as well as independently derived equations of state, but so far have not involved direct extrapolations from Earth's seismic model: the Preliminary Reference Earth Model (PREM). To facilitate more detailed compositional comparisons between small exoplanets and the Earth, we derive here a semi-empirical mass-radius relation for two-layer rocky planets based on PREM, , where CMF stands for core mass fraction. It is applicable to 1 ∼ 8 M⊕ and a CMF of 0.0 ∼ 0.4. Applying this formula to Earth and Venus and several known small exoplanets with radii and masses measured to better than ∼30% precision gives a CMF fit of 0.26 0.07.
Summary Anxiety disorders (separation anxiety disorder, selective mutism, specific phobias, social anxiety disorder, panic disorder, agoraphobia, and generalised anxiety disorder) are common and ...disabling conditions that mostly begin during childhood, adolescence, and early adulthood. They differ from developmentally normative or stress-induced transient anxiety by being marked (ie, out of proportion to the actual threat present) and persistent, and by impairing daily functioning. Most anxiety disorders affect almost twice as many women as men. They often co-occur with major depression, alcohol and other substance-use disorders, and personality disorders. Differential diagnosis from physical conditions—including thyroid, cardiac, and respiratory disorders, and substance intoxication and withdrawal—is imperative. If untreated, anxiety disorders tend to recur chronically. Psychological treatments, particularly cognitive behavioural therapy, and pharmacological treatments, particularly selective serotonin-reuptake inhibitors and serotonin–noradrenaline-reuptake inhibitors, are effective, and their combination could be more effective than is treatment with either individually. More research is needed to increase access to and to develop personalised treatments.
We report a method for high-precision potassium isotope measurements that improves by an order of magnitude the precision compared to previous methods. The purification of K is achieved through ion ...exchange chromatography on AG50W-X8 cation exchange resins. The 41K/39K ratios are analyzed with a GV Instruments IsoProbe P Multiple-Collector Inductively Coupled Plasma Mass Spectrometer (MC-ICP-MS) equipped with a hexapole collision gas cell. With this technique, the argon-hydride interferences as well as the large 40Ar+ peak from the Ar-plasma are eliminated. The 41K/39K ratios can thus be obtained with a precision of 0.05permil. The precision and accuracy of this method is validated with gravimetrically determined 41K or 39K enriched standards. New precise K isotopic compositions of three terrestrial basalts (BCR-2, BHVO-1 and a MORB) are also reported. These basalts have indistinguishable K isotopic compositions and are used to define a reference value of −0.479±0.027permil for the 41K/39K ratio of the Bulk Silicate Earth (BSE) relative to a Merck Suprapur potassium nitrate standard. Seawater and sylvites from evaporite deposits have similar 41K/39K ratios, but higher by up to 0.227permil compared to the Merck Suprapur standard. Other commercially available K-salts/solutions also have 41K/39K ratios similar to the Merck standard, while a SPEX K-chloride was higher by 0.384permil. This shows that K isotope variations will be useful as a tracer in low-temperature geochemistry processes.
Social anxiety disorder Stein, Murray B, Prof; Stein, Dan J, Prof
Lancet,
2008-Mar-29, Letnik:
371, Številka:
9618
Journal Article
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Summary Our understanding of social anxiety disorder (also known as social phobia) has moved from rudimentary awareness that it is not merely shyness to a much more sophisticated appreciation of its ...prevalence, its chronic and pernicious nature, and its neurobiological underpinnings. Social anxiety disorder is the most common anxiety disorder; it has an early age of onset—by age 11 years in about 50% and by age 20 years in about 80% of individuals—and it is a risk factor for subsequent depressive illness and substance abuse. Functional neuroimaging studies point to increased activity in amygdala and insula in patients with social anxiety disorder, and genetic studies are increasingly focusing on this and other (eg, personality trait neuroticism) core phenotypes to identify risk loci. A range of effective cognitive behavioural and pharmacological treatments for children and adults now exists; the challenges lie in optimum integration and dissemination of these treatments, and learning how to help the 30–40% of patients for whom treatment does not work.
The radii and orbital periods of 4,000+ confirmed/candidate exoplanets have been precisely measured by the Kepler mission. The radii show a bimodal distribution, with two peaks corresponding to ...smaller planets (likely rocky) and larger intermediate-size planets, respectively. While only the masses of the planets orbiting the brightest stars can be determined by ground-based spectroscopic observations, these observations allow calculation of their average densities placing constraints on the bulk compositions and internal structures. However, an important question about the composition of planets ranging from 2 to 4 Earth radii (R⊕) still remains. They may either have a rocky core enveloped in a H₂–He gaseous envelope (gas dwarfs) or contain a significant amount of multicomponent, H₂O-dominated ices/fluids (water worlds). Planets in the mass range of 10–15 M⊕, if half-ice and half-rock by mass, have radii of 2.5 R⊕, which exactly match the second peak of the exoplanet radius bimodal distribution. Any planet in the 2- to 4-R⊕ range requires a gas envelope of at most a few mass percentage points, regardless of the core composition. To resolve the ambiguity of internal compositions, we use a growth model and conduct Monte Carlo simulations to demonstrate that many intermediate-size planets are “water worlds.”
Despite heightened awareness of the clinical significance of social phobia, information is still lacking about putative subtypes, functional impairment, and treatment-seeking. New epidemiologic data ...on these topics are presented from the National Comorbidity Survey Replication (NCS-R).
The NCS-R is a nationally representative household survey fielded in 2001-2003. The World Health Organization (WHO) Composite International Diagnostic Interview Version 3.0 (CIDI 3.0) was used to assess 14 performance and interactional fears and DSM-IV social phobia.
The estimated lifetime and 12-month prevalence of social phobia are 12.1% and 7.1% respectively. Performance and interactional fears load onto a single latent factor, and there is little evidence for distinct subtypes based either on the content or the number of fears. Social phobia is associated with significant psychiatric co-morbidity, role impairment, and treatment-seeking, all of which have a dose-response relationship with number of social fears. However, social phobia is the focus of clinical attention in only about half of cases where treatment is obtained. Among non-co-morbid cases, those with the most fears were least likely to receive social phobia treatment.
Social phobia is a common, under-treated disorder that leads to significant functional impairment. Increasing numbers of social fears are associated with increasingly severe manifestations of the disorder.
Objective:Anxiety disorders are common and often disabling. The goal of this study was to examine the genetic architecture of anxiety disorders and anxiety symptoms, which are also frequently ...comorbid with other mental disorders, such as major depressive disorder.Methods:Using one of the world’s largest biobanks including genetic, environmental, and medical information, the Million Veteran Program, the authors performed a genome-wide association study (GWAS) of a continuous trait for anxiety (based on score on the Generalized Anxiety Disorder 2-item scale GAD-2, N=199,611) as the primary analysis and self-report of physician diagnosis of anxiety disorder (N=224,330) as a secondary analysis.Results:The authors identified five genome-wide significant signals for European Americans and one for African Americans on GAD-2 score. The strongest were on chromosome 3 (rs4603973) near SATB1, a global regulator of gene expression, and on chromosome 6 (rs6557168) near ESR1, which encodes an estrogen receptor. The locus identified on chromosome 7 (rs56226325, MAF=0.17) near MAD1L1 was previously identified in GWASs of bipolar disorder and schizophrenia. The authors replicated these findings in the summary statistics of two major published GWASs for anxiety, and also found evidence of significant genetic correlation between the GAD-2 score results and previous GWASs for anxiety (rg=0.75), depression (rg=0.81), and neuroticism (rg=0.75).Conclusions:This is the largest GWAS of anxiety traits to date. The authors identified novel genome-wide significant associations near genes involved with global regulation of gene expression (SATB1) and the estrogen receptor alpha (ESR1). Additionally, the authors identified a locus (MAD1L1) that may have implications for genetic vulnerability across several psychiatric disorders. This work provides new insights into genetic risk mechanisms underpinning anxiety and related psychiatric disorders.
Resilience refers to an individual's ability to thrive despite adversity. The current study examined the psychometric properties of the Connor–Davidson Resilience Scale (CD‐RISC). Three undergraduate ...samples (ns < 500) were used to determine the factor structure of the CD‐RISC. The first two samples were used to conduct exploratory factor analysis (EFA), and the third was used for confirmatory factor analysis. The EFA showed that the CD‐RISC had an unstable factor structure across two demographically equivalent samples. A series of empirically driven modifications was made, resulting in a 10‐item unidimensional scale that demonstrated good internal consistency and construct validity. Overall, the 10‐item CD‐RISC displays excellent psychometric properties and allows for efficient measurement of resilience.
In a trial involving 304 veterans with stable PTSD, prazosin did not alleviate distressing dreams and did not improve sleep quality or overall clinical symptoms over 10 or 26 weeks. This result is in ...contrast to findings in several previous smaller or briefer trials.
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