459 research outputs found
Agenda 21 local como herramienta de desarollo sostenible : La situación en Suiza
1999an Suitzak bere konpromisoa bete zuen, garapen iraunkorra Konstituzioan barneratu baitzuen. Herrialde hau Tokiko Agenda 21 delakoaren moduko prozesu zehatzak sustatzeko hainbat estrategia ari da probatzen. 2005eko uztailean, Suitzako udalerrien % 4 baino ez zegoen prozesu honetan sartuta; hau da, biztanleriaren % 29. Suitzako tokiko agintaritzek, sistema federala dela eta, autonomia handia izan dute aspalditik; gainera, biztanleek demokrazia zuzeneko sistema suitzarraren bidez, Europako beste herrialde batzuetan baino zuzenago parte har dezakete erabaki politikoak hartzerakoan. Epe luzera, Garapen Iraunkorreko Estrategia Nazionalaren helburua garapen iraunkorra agintari publikoen jarduera eta politika guztietan barneratzea da.In 1999, Switzerland made good its pledge by writing sustainable development into its Constitution. Different strategies and programs are going on to promote Agenda 21-like processes. In July 2005, just 4% of municipalities were involved in the process, though this does represent 29% of the population. In Switzerland, under the country¿s federal system, local authorities have for a long time enjoyed considerable autonomy and, under the Swiss system of direct democracy, citizens are able to participate more fully in all political decision-making than in other countries. In the longer term, the aim of the National Sustainable development Strategy is to include sustainable development in all the policies and activities of public authorities.En 1999, Suiza cumplió con su compromiso al incluir el desarrollo sostenible en la Constitución. Este país está ensayando diferentes estrategias para fomentar determinados procesos del estilo de la Agenda 21 Local. En julio de 2005, tan sólo un 4% de los municipios suizos se habían involucrado en este proceso, si bien representan un 29% de la población. Las autoridades locales suizas, bajo un sistema federal, han disfrutado durante mucho tiempo de una autonomía considerable. Y los ciudadanos, mediante el sistema suizo de democracia directa, pueden participar de una manera más activa que en otros países europeos en la toma de decisiones políticas. A largo plazo, el objetivo de la Estrategia Nacional de Desarrollo Sostenible es incluir el desarrollo sostenible en todas las actividades y políticas de las autoridades pública
Positron localization effects on the Doppler broadening of the annihilation line: Aluminum as a case study
The coincidence Doppler broadening (CDB) technique is widely used to measure one-dimensional momentum distributions of annihilation photons, with the aim of obtaining information on the chemical environment of open-volume defects. However, the quantitative analysis of CDB spectra needs to include also purely geometrical effects. A demonstration is given here, on the basis of CDB spectra measured in quenched and in deformed pure aluminum. The comparison of the experimental results with ab initio computations shows that the observed differences come from the difference in free volume seen by positrons trapped in quenched-in vacancies or in vacancylike defects associated to dislocations. The computation reproduces accurately all details of CDB spectra, including the peak near the Fermi break, which is due to the zero-point motion of the confined positron.Peer reviewe
Nonpolar optical scattering of positronium in magnesium fluoride
We report the results of the analysis of the temperature broadening of the
momentum distribution of delocalized Positronium (Ps) in Magnesium Fluoride in
terms of optical deformation-potential scattering model (long-wavelength
optical phonons). The Ps optical deformation-potential coupling constant
in MgF has been determined to be eV/cm.
We also show that the Ps momentum distribution is sensitive to second-order
phase transitions in those crystals where optical deformation-potential
scattering is allowed in one and forbidden in another crystalline phase
Defect Characterization in SiGe/SOI Epitaxial Semiconductors by Positron Annihilation
The potential of positron annihilation spectroscopy (PAS) for defect characterization at the atomic scale in semiconductors has been demonstrated in thin multilayer structures of SiGe (50 nm) grown on UTB (ultra-thin body) SOI (silicon-on-insulator). A slow positron beam was used to probe the defect profile. The SiO2/Si interface in the UTB-SOI was well characterized, and a good estimation of its depth has been obtained. The chemical analysis indicates that the interface does not contain defects, but only strongly localized charged centers. In order to promote the relaxation, the samples have been submitted to a post-growth annealing treatment in vacuum. After this treatment, it was possible to observe the modifications of the defect structure of the relaxed film. Chemical analysis of the SiGe layers suggests a prevalent trapping site surrounded by germanium atoms, presumably Si vacancies associated with misfit dislocations and threading dislocations in the SiGe films
Investigation of the chemical vicinity of crystal defects in ion-irradiated Mg and AZ31 with coincident Doppler broadening spectroscopy
Crystal defects in magnesium and magnesium based alloys like AZ31 are of
major importance for the understanding of their macroscopic properties. We have
investigated defects and their chemical surrounding in Mg and AZ31 on an atomic
scale with Doppler broadening spectroscopy of the positron annihilation
radiation. In these Doppler spectra the chemical information and the defect
contribution have to be thoroughly separated. For this reason samples of
annealed Mg were irradiated with Mg-ions in order to create exclusively
defects. In addition Al- and Zn-ion irradiation on Mg-samples was performed in
order to create samples with defects and impurity atoms. The ion irradiated
area on the samples was investigated with laterally and depth resolved positron
Doppler broadening spectroscopy (DBS) and compared with preceding
SRIM-simulations of the vacancy distribution, which are in excellent agreement.
The investigation of the chemical vicinity of crystal defects in AZ31 was
performed with coincident Doppler broadening spectroscopy (CDBS) by comparing
Mg-ion irradiated AZ31 with Mg-ion irradiated Mg. No formation of
solute-vacancy complexes was found due to the ion irradiation, despite the high
defect mobility.Comment: Submitted to Physical Review B on March 20 20076. Revised version
submitted on September 28 2007. Accepted on October 19 200
Cancellation of probe effects in measurements of spin polarized momentum density by electron positron annihilation
Measurements of the two dimensional angular correlation of the
electron-positron annihilation radiation have been done in the past to detect
the momentum spin density and the Fermi surface. We point out that the momentum
spin density and the Fermi Surface of ferromagnetic metals can be revealed
within great detail owing to the large cancellation of the electron-positron
matrix elements which in paramagnetic multiatomic systems plague the
interpretation of the experiments. We prove our conjecture by calculating the
momentum spin density and the Fermi surface of the half metal CrO2, who has
received large attention due to its possible applications as spintronics
material
Analysis of electron-positron momentum spectra of metallic alloys as supported by first-principles calculations
Electron-positron momentum distributions measured by the coincidence Doppler
broadening method can be used in the chemical analysis of the annihilation
environment, typically a vacancy-impurity complex in a solid. In the present
work, we study possibilities for a quantitative analysis, i.e., for
distinguishing the average numbers of different atomic species around the
defect. First-principles electronic structure calculations self-consistently
determining electron and positron densities and ion positions are performed for
vacancy-solute complexes in Al-Cu, Al-Mg-Cu, and Al-Mg-Cu-Ag alloys. The
ensuing simulated coincidence Doppler broadening spectra are compared with
measured ones for defect identification. A linear fitting procedure, which uses
the spectra for positrons trapped at vacancies in pure constituent metals as
components, has previously been employed to find the relative percentages of
different atomic species around the vacancy [A. Somoza et al. Phys. Rev. B 65,
094107 (2002)]. We test the reliability of the procedure by the help of
first-principles results for vacancy-solute complexes and vacancies in
constituent metals.Comment: Submitted to Physical Review B on September 19 2006. Revised version
submitted on November 8 2006. Published on February 14 200
Practicing self-compassion weakens the relationship between fear of receiving compassion and the desire to conceal negative experiences from others
This is a post-peer-review, pre-copyedit version of an article published in Mindfulness. The final
authenticated version is available online from Springer at: http://dx.doi.org/10.1007/s12671-017-0792-0Disclosure of personal distress is linked to important inter- and intrapersonal benefits. However, people who tend to view self-disclosure as being risky are likely to conceal their feelings and forgo opportunities to receive valuable social support. One such group of people may be those who fear receiving compassion. The current study of 85 female undergraduates investigated (a) whether fear of receiving compassion would predict decreased distress disclosure, and (b) whether inducing a self-compassionate mindset could help to temper the association between fear of receiving compassion and perceived risks of revealing one’s distress to others. Participants completed self-report questionnaires to measure trait-like fears of receiving compassion as well as general distress disclosure tendencies. They were then enrolled in a laboratory experiment in which they recalled a personal past negative experience and were randomly assigned to write about it in a self-compassionate, self-esteem enhancing, or non-directive way. Finally, they rated how risky disclosing their experience would feel and disclosed the event in a written letter to another person. At a trait level, results indicated that the more participants feared receiving compassion, the less they tended to disclose. Moreover, self-compassion training – but neither of the comparison conditions – significantly weakened the positive link between fear of receiving compassion and perceived risks of distress disclosure. These novel findings suggest that practicing self-compassion could help to neutralize the maladaptive relationship between fear of receiving compassion and perceived risk of disclosure.Social Sciences and Humanities Research Council of Canada, Grant 435-2012-0017 || Social Sciences and Humanities Research Council of Canada, Grant 430-2013-000757|| Canada Research Chairs, Grant 950-22314
AEGIS at CERN: Measuring Antihydrogen Fall
The main goal of the AEGIS experiment at the CERN Antiproton Decelerator is
the test of fundamental laws such as the Weak Equivalence Principle (WEP) and
CPT symmetry. In the first phase of AEGIS, a beam of antihydrogen will be
formed whose fall in the gravitational field is measured in a Moire'
deflectometer; this will constitute the first test of the WEP with antimatter.Comment: Presented at the Fifth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 28-July 2, 201
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