8,824 research outputs found
CNONa and 12C/13C in giants of 10 open clusters
Evolved low-mass stars of a wide range of metallicity bear signatures of a
non-standard mixing event in their surface abundances of Li, C, and N, and in
their 12C/13C ratio. A Na overabundance has also been reported in some giants
of open clusters but remains controversial. The cause of the extra-mixing has
been attributed to thermohaline convection that should take place after the RGB
bump for low-mass stars and on the early-AGB for more massive objects. To track
the occurrence of this process over a wide mass range, we derive in a
homogeneous way the abundances of C, N, O, and Na, as well as the 12C/13C ratio
in a sample of 31 giants of 10 open clusters with turn-off masses from 1.7 to
3.1 Msun. A group of first ascent red giants with M/Msun \leq 2.5 exhibits
lower [N/C] ratios than those measured in clump giants of the same mass range,
suggesting an additional increase in the [N/C] ratio after the first dredge-up.
The sodium abundances corrected from NLTE are found to be about solar. [Na/Fe]
shows a slight increase of 0.10 dex as a function of stellar mass in the 1.8 to
3.2 Msun range covered by our sample, in agreement with standard first
dredge-up predictions. Our results do not support previous claims of sodium
overabundances as high as +0.60 dex. An anti-correlation between 12C/13C and
turn-off mass is identified and interpreted as being caused by a post-bump
thermohaline mixing. Moreover, we find low 12C/13C ratios in a few
intermediate-mass early-AGB stars, confirming that an extra-mixing process also
operates in stars that do not experienced the RGB bump. In this case, the
extra-mixing possibly acts on the early-AGB, in agreement with theoretical
expectations for thermohaline mixing. [abridged]Comment: A&A accepted, revised versio
Assessing somatization in urologic chronic pelvic pain syndrome
BACKGROUND: This study examined the prevalence of somatization disorder in Urological Chronic Pelvic Pain Syndrome (UCPPS) and the utility of two self-report symptom screening tools for assessment of somatization in patients with UCPPS.
METHODS: The study sample included 65 patients with UCPPS who enrolled in the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Study at Washington University. Patients completed the PolySymptomatic PolySyndromic Questionnaire (PSPS-Q) (n = 64) and the Patient Health Questionnaire-15 Somatic Symptom Severity Scale (PHQ-15) (n = 50). Review of patient medical records found that only 47% (n = 30) contained sufficient documentation to assess Perley-Guze criteria for somatization disorder.
RESULTS: Few (only 6.5%) of the UCPPS sample met Perley-Guze criteria for definite somatization disorder. Perley-Guze somatization disorder was predicted by definite PSPS-Q somatization with at least 75% sensitivity and specificity. Perley-Guze somatization disorder was predicted by severe (\u3e 15) PHQ-15 threshold that had \u3e 90% sensitivity and specificity but was met by only 16% of patients. The moderate (\u3e 10) PHQ-15 threshold had higher sensitivity (100%) but lower specificity (52%) and was met by 52% of the sample.
CONCLUSIONS: The PHQ-15 is brief, but it measures symptoms constituting only one dimension of somatization. The PSPS-Q uniquely captures two conceptual dimensions inherent in the definition of somatization disorder, both number of symptoms and symptom distribution across multiple organ systems, with relevance for UCPPS as a syndrome that is not just a collection of urological symptoms but a broader syndrome with symptoms extending beyond the urological system
Limited access orders in the developing world :a new approach to the problems of development
The upper-income, advanced industrial countries of the world today all have market economies with open competition, competitive multi-party democratic political systems, and a secure government monopoly over violence. Such open access orders, however, are not the only norm and equilibrium type of society. The middle and low-income developing countries today, like all countries before about 1800, can be understood as limited access orders that maintain their equilibrium in a fundamentally different way. In limited access orders, the state does not have a secure monopoly on violence, and society organizes itself to control violence among the elite factions. A common feature of limited access orders is that political elites divide up control of the economy, each getting some share of the rents. Since outbreaks of violence reduce the rents, the elite factions have incentives to be peaceable most of the time. Adequate stability of the rents and thus of the social order requires limiting access and competition-hence a social order with a fundamentally different logic than the open access order. This paper lays out such a framework and explores some of its implications for the problems of development today.Corporate Law,Labor Policies,Public Sector Corruption&Anticorruption Measures,E-Business,Disability
From Anti-equilibrium to The Socialist System and Beyond
This essay attempts to understand János Kornai’s works from a political economy perspective. It argues that Kornai has significantly contributed to the formation of a new paradigm of political economy. The main endeavor of Kornai has been the combination of analytical concepts of economics with the empirical description of real economies. After a certain period of theoretical experimentation János Kornai formulated his research program that can be called the shortage economy explanation of the socialist system. The Economics of Shortage and The Socialist System have created a new theoretical paradigm in a framework in which it has become possible to establish a connection between the analytical and empirical, universal and historical aspects of the theory studying the socialist system as a real economic entity. János Kornai has built his analysis of the socialist system on the primary role of politics in the creation of economic institutions. In his present work on capitalism he has extended this thesis to the capitalist system. This seems to be an important contribution of his to a new political economy paradigm that is just in the process of formation
Tackling concentrated worklessness: integrating governance and policy across and within spatial scales
Spatial concentrations of worklessness remained a key characteristic of labour markets in advanced industrial economies, even during the period of decline in aggregate levels of unemployment and economic inactivity evident from the late 1990s to the economic downturn in 2008. The failure of certain localities to benefit from wider improvements in regional and national labour markets points to a lack of effectiveness in adopted policy approaches, not least in relation to the governance arrangements and policy delivery mechanisms that seek to integrate residents of deprived areas into wider local labour markets. Through analysis of practice in the British context, we explore the difficulties of integrating economic and social policy agendas within and across spatial scales to tackle problems of concentrated worklessness. We present analysis of a number of selected case studies aimed at reducing localised worklessness and identify the possibilities and constraints for effective action given existing governance arrangements and policy priorities to promote economic competitiveness and inclusion
Climbing as if you care: Rock climbing at Kura Tawhiti/Castle Hill as a place-based approach to sustainability
This article explores ways that climbers engage with climbing areas and highlights opportunities that climbing offers to develop, through place-based education approaches, an ethic of care for these places. Challenges include moving people beyond the notion that climbs are resources to be ‘consumed’ by making them aware of the need to engage in culturally and environmentally respectful practices when climbing in natural environments. Opportunities include the revisiting of familiar problems over time to develop ongoing associations, the physicality and sociality of the climbing, and opportunities to experience beauty and spiritual connections. This study focuses on an area in Aotearoa New Zealand called Kura Tawhiti/Castle Hill, famous for its world class bouldering. The article ends with the conclusion that even though climbers connect to places in different ways, setting these connections within the context of place-based education still has the potential to foster the ethic and care that underpins practising sustainability
Tasks for multivariate network analysis
In Chap. 1, a multivariate network was defined as having two important characteristics. First, nodes are connected to each other via links; there is topological structure. Second, being multivariate, nodes and links have attributes associated with them, with these attributes having a value. In this chapter, we describe tasks associated with multivariate networks. We consider a task to be an activity that a user wishes to accomplish by interacting with a visual representation of a multivariate network. This implies that there is user intent [13], and that the network has been presented visually. At the highest level, this intent is usually described as the goal of obtaining insight about the data being studied [6]
12C/13C ratios in giants of open clusters
The carbon isotopic ratio, 12C/13C, is a tracer of the mixing events during the evolution along the giant branch, due to the conversion of 12C into 13C (and 14N) via the CN cycle. A decrease of this ratio from 90, the solar value, to 20-25, is expected due to the first dredge-up. However, ratios down to 3-4, the CN cycle equilibrium value, have been observed in giants of the field, of globular and of open clusters. Observations seem to indicate a non-standard mixing in the RGB, probably beginning in the luminosity bump, when the outward moving hydrogen burning shell crosses the molecular weight barrier left by the convective layer in its maximum extent. We are currently analyzing a sample of 24 giants in 8 open clusters for which we determined 12C/13C from high resolution, high signal to noise spectra using spectrum synthesis. In this work we discuss the general characteristics of our results in comparison to previous analyses of giants in open clusters available in the literatur
The radio lighthouse CU Virginis: the spindown of a single main sequence star
The fast rotating star CU Virginis is a magnetic chemically peculiar star
with an oblique dipolar magnetic field. The continuum radio emission has been
interpreted as gyrosyncrotron emission arising from a thin magnetospheric
layer. Previous radio observations at 1.4 GHz showed that a 100% circular
polarized and highly directive emission component overlaps to the continuum
emission two times per rotation, when the magnetic axis lies in the plane of
the sky. This sort of radio lighthouse has been proposed to be due to cyclotron
maser emission generated above the magnetic pole and propagating
perpendicularly to the magnetic axis. Observations carried out with the
Australia Telescope Compact Array at 1.4 and 2.5 GHz one year after this
discovery show that this radio emission is still present, meaning that the
phenomenon responsible for this process is steady on a timescale of years. The
emitted radiation spans at least 1 GHz, being observed from 1.4 to 2.5 GHz. On
the light of recent results on the physics of the magnetosphere of this star,
the possibility of plasma radiation is ruled out. The characteristics of this
radio lighthouse provides us a good marker of the rotation period, since the
peaks are visible at particular rotational phases. After one year, they show a
delay of about 15 minutes. This is interpreted as a new abrupt spinning down of
the star. Among several possibilities, a quick emptying of the equatorial
magnetic belt after reaching the maximum density can account for the magnitude
of the breaking. The study of the coherent emission in stars like CU Vir, as
well as in pre main sequence stars, can give important insight into the angular
momentum evolution in young stars. This is a promising field of investigation
that high sensitivity radio interferometers such as SKA can exploit.Comment: Accepted to MNRAS, 8 pages, 7 figures, updated versio
Analysis of clean coal technology in Nigeria for energy generation
Abstract: An analysis of clean coal technologies for the recovery of energy from Nigerian coals was carried out. The coal mines studied are Onyeama, Ogwashi, Ezimo, Inyi, Amasiodo, Okaba, Lafia-Obi, Owukpa Owukpa, Ogboyoga and Okpara. The estimated reserves of the ten coal deposit amount to 2.1 Gt, which is about 84 % of the total coal reserves of the country 2.5 Gt of coal Nigeria. The key clean coal technologies studied are Ultra-Supercritical Combustion (USC), Supercritical-Fluidised Bed Combustion (FBC), Integrated Gasification Combined Cycle (IGCC) and Coal bed Methane (CBM) and the results were compared with conventional subcritical pulverised fuel combustion (PF). The total potential energy recovery from these technologies are: PF 5800 TWh, FBC 7250 TWh, IGCC 7618 TWh, and USC 8519 TWh. This indicates an increase of about 31% in the total electricity generation if USC technology is used instead of the conventional sub-critical PF technology..
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