Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees

ABSOLUTE, PROMPT GAMMA-RAY SPECTROSCOPY AND THE DETERMINATION OF FUNDAMENTAL CONSTANTS

Il existe une échelle de longueur d'onde absolue précise pour les radiations électromagnétiques qui s'étendent des microondes aux rayons γ ayant des énergies inférieures à 1 MeV. Cette échelle commence avec l'horloge à jet atomique de caesium (et ainsi le mètre SI) et continue jusqu'au laser HeNe stabilisé à l'iode. Un tel laser est alors utilisé pour déterminer l'espacement du réseau d'un cristal de Si utilisant l'interférométrie optique à rayons X. Des cristaux calibrés précisément sont alors utilisés dans un diffractomètre à cristal plat pour déterminer des longueurs d'onde absolues de rayon γ. Nous proposons d'étendre cette échelle à la région 1-10 MeV. Ceci requiert l'emploi de sources intérieures à la pile pour pouvoir examiner les rayons γ rapides provenant de réactions n-γ.There currently exists a highly accurate absolute wavelength scale for electromagnetic radiation which extends from microwaves to gamma-rays having energies less than ~ 1 MeV. This scale begins with the cesium atomic beam clock (and thus the SI meter) and continues through the iodine stabilized HeNe laser. Such a laser is then used to determine the lattice spacing of a single crystal of Si using x-ray/optical interferometry. Accurately calibrated crystals are then used in a flat crystal diffractometer to determine absolute gamma-ray wavelengths. We propose to extend this scale to the region of ~ 1-10 MeV. This requires the use of in-pile sources for the examination of prompt gamma-rays from n-γ reactions

SYSTEMATICS OF X-RAY TRANSITION ENERGIES FOR HIGH-Z ATOMS

Experimental and theoretical x-ray transition energies are precisely estimated and compared for 40<Z<100. All allowed and forbidden intervals for the n=1 to n=2, 3 levels are determined. The experimental values are derived from absolute wavelength measurements of Kα and Kβ transitions and from L series x-ray measurements. The theoretical values are obtained using a multiconfiguration Dirac-Fock code with some modifications in the Lamb shift calculations. Comparison between experiment and theory for Z<85 now provides a more coherent qualitative picture : (1) for the 1s-1→2s-1, 1s-1→3s-1, and 1s-1→3p-1 transitions, experimental energies are 5-10 eV larger, consistent with the magnitude and sign of the level shifts resulting from pair correlation and configuration mixing with Coster-Kronig and Auger transitions which were not included in the theory and (2) for the 1s1→2p-1 and 1s-1→3d-1 transitions, experimental energies are ≈ 3 eV larger, of which ≈ 1.5 eV can be attributed to pair correlation leaving ≈ 1.5 eV to higher order effects not included in our theory

Doing extra-ordinariness: trans-men's accomplishment of `authenticity' in the research interview

Discussions concerning transsexual identities consider the self representations of transsexuals as either determined through medical discourses and practices, and thus as constructed and inauthentic or, alternatively, as expressive of an interior and thus ‘authentic’ essential self. In contrast to each of these arguments, this article highlights the significance of social interaction to transsexual authenticity and explores, specifically, how this can be analytically captured and presented in the context of interview-based research. The article applies analytic techniques drawn from fine-grain discourse analysis to research interviews carried out with female to male transsexuals. Through this method of analysis transsexual authenticity is treated as neither determined through medical discourses nor as interior to the self, but rather as a ‘live’ interactional accomplishment. By revealing the discursive identity work undertaken by the interviewees, the article demonstrates a constructionist approach to transsexual authenticity which, contrary to essentialist critiques, succeeds in foregrounding transsexuals as ‘constructing subjects’

Safety aspects of an inertial confinement fusion reactor

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

The prevalence and effects of Adult Attention-Deficit/hyperactivity Disorder (ADHD) on the performance of workers: Results from the WHO World Mental Health Survey Initiative

OBJECTIVES: To estimate the prevalence and workplace consequences of adult attention-deficit/hyperactivity disorder (ADHD). METHODS: Ann ADHD screen was administered to 18-44 year-old respondents in ten national surveys in the WHO World Mental Health (WMH) Survey Initiative (n = 7075 in paid or self employment; response rate 45.9-87.7% across countries). Blinded clinical reappraisal interviews were administered in the US to calibrate the screen.. Days out of role were measured in the WHO Disability Assessment Schedule (WHO-DAS). Questions were also asked about ADHD treatment. RESULTS: An average of 3.5% of workers in the ten countries was estimated to meet DSM-IV criteria for adult ADHD (inter-quartile range: 1.3-4.9%). ADHD was more common among males than females and less common among professionals than other workers. ADHD was associated with a statistically significant 22.1 annual days of excess lost role performance compared to otherwise similar respondents without ADHD. No difference in the magnitude of this effect was found by occupation, education, age, gender, or partner status. This effect was most pronounced in Colombia, Italy, Lebanon, and the US. Although only a small minority of workers with ADHD ever received treatment for this condition, higher proportions were treated for comorbid mental-substance disorders. CONCLUSIONS: ADHD is a relatively common condition among working people in the countries studied and is associated with high work impairment in these countries. This impairment, in conjunction with the low treatment rate and the availability of cost-effective therapies, suggests that ADHD would be a good candidate for targeted workplace screening and treatment programs