Speed tuning of direction repulsion describes an inverted U-function

Direction repulsion describes the phenomenon in which observers typically overestimate the direction difference between two superimposed motions moving in different directions (Marshak & Sekuler, Science 205(1979) 1399). Previous research has found that, when a relatively narrow range of distractor speeds is considered, direction repulsion of a target motion increases monotonically with increasing speed of the distractor motion. We sought to obtain a more complete measurement of this speed-tuning function by considering a wider range of distractor speeds than has previously been used. Our results show that, contrary to previous reports, direction repulsion as a function of distractor speed describes an inverted U-function. For a target of 2.5deg/s, we demonstrate that the attenuation of repulsion magnitude with high-speed disractors can be largely explained in terms of the reduced apparent contrast of the distractor. However, when we reduce target motion speed, this no longer holds. When considered from the perspective of Edwards et al.s (Edwards, Badcock, & Smith, Vision Research 38 (1998) 1573) two global-motion channels, our results suggest that direction repulsion is speed dependent when the distractor and target motions are processed by different globalmotion channels, but is not speed dependent when both motions are processed by the same, high-speed channel. The implications of these results for models of direction repulsion are discussed.

Soil-Landscape relationships at the lower reaches of a watershed at Bear Creek near Oak Ridge, Tennessee

The watersheds at Bear Creek, Oak Ridge, TN, have similar soil–landscape relationships. The lower reaches of many of these watersheds consist of headwater riparian wetlands situated between sloping non-wetland upland zones. The objectives of this study are to examine the effects of (i) slope and geomorphic processes, (ii) human impacts, and (iii) particular characteristics of soils and saprolite that may effect drainage and water movement in the wetlands and adjacent landscapes in one of these watersheds. A transect was run from west to east in a hydrological monitored area at the lower reaches of a watershed on Bear Creek. This transect extended from a steep side slope position across a floodplain, a terrace, and a shoulder slope. On the upland positions of the Nolichucky Shale, mass wasting, overland flow and soil creep currently inhibit soil formation on the steep side slope position where a Typic Dystrudept is present, while soil stability on the shoulder slope has resulted in the formation of a well-developed Typic Hapludult. In these soils, argillic horizons occur above C horizons on less sloping gradients in comparison to steeper slopes, which have Bw horizons over Cr (saprolite) material. A riparian wetland area occupies the floodplain section, where a Typic Endoaquept is characterized by poorly drained conditions that led to the development of redoximorphic features (mottling), gleying, organic matter accumulation, and minimal development of subsurface horizons. A thin colluvial deposit overlies a thick well developed Aquic Hapludalf that formed in alluvial sediments on the terrace position. The colluvial deposit from the adjacent shoulder slope is thought to result from soil creep and anthropogenic erosion caused by past cultivation practices. Runoff from the adjacent sloping landscape and groundwater from the adjacent wetland area perhaps contribute to the somewhat poorly drained conditions of this profile. Perched watertables occur in upland positions due to dense saprolite and clay plugging in the shallow zones of the saprolite. However, no redoximorphic features are observed in the soil on the side slope due to high runoff. Remnants of the underlying shale saprolite, which occur as small discolored zones resembling mottles, are also present. The soils in the study have a CEC of

Fe XIII emission lines in active region spectra obtained with the Solar Extreme-Ultraviolet Research Telescope and Spectrograph

Recent fully relativistic calculations of radiative rates and electron impact excitation cross-sections for FeXIII are used to generate emission-line ratios involving 3s23p2-3s3p3 and 3s23p2-3s23p3d transitions in the 170-225 and 235-450 Å wavelength ranges covered by the Solar Extreme-Ultraviolet Research Telescope and Spectrograph (SERTS). A comparison of these line ratios with SERTS active region observations from rocket flights in 1989 and 1995 reveals generally very good agreement between theory and experiment. Several new FeXIII emission features are identified, at wavelengths of 203.79, 259.94, 288.56 and 290.81 Å. However, major discrepancies between theory and observation remain for several FeXIII transitions, as previously found by Landi and others, which cannot be explained by blending. Errors in the adopted atomic data appear to be the most likely explanation, in particular for transitions which have 3s23p3d1D2 as their upper level. The most useful FeXIII electron-density diagnostics in the SERTS spectral regions are assessed, in terms of the line pairs involved being (i) apparently free of atomic physics problems and blends, (ii) close in wavelength to reduce the effects of possible errors in the instrumental intensity calibration, and (iii) very sensitive to changes in Ne over the range 108-1011cm-3. It is concluded that the ratios which best satisfy these conditions are 200.03/202.04 and 203.17/202.04 for the 170-225 Å wavelength region, and 348.18/320.80, 348.18/368.16, 359.64/348.18 and 359.83/368.16 for 235-450 Å.

Emission-line ratios for [N II] in gaseous nebulae and a comparison between theory and observation

R-matrix calculations of electron impact excitation rates among the 2s(2)2p(2) P-3, D-1, S-1, and 2s2p(3) S-5 levels of N II are presented. These results are used in conjunction with other recent calculations of electron impact excitation rates and Einstein A-coefficients for N II to derive the emission-line ratio: ratio diagrams and where (R-1, R-2) (R-1, R-3), where R-1 = I(5756.2 Angstrom)/I(6549.9 + 6585.2 Angstrom), R-2 = I(2143.5 Angstrom)/I(6549.9 + 6585.2 Angstrom), and R-3 = I(2139.7 Angstrom)/I(6549.9 + 658.2 Angstrom), for a range of electron temperatures (T-e = 5000-20,000 K) and electron densities (N-e = 10(2)-10(7) cm(-3)) appropriate to gaseous nebulae. These diagrams should, in principle, allow the simultaneous determination of T-e and N-e from measurements of the [N II] lines in a spectrum. Plasma parameters deduced for a sample of gaseous nebulae, using observational data obtained from ground-based telescopes plus the International Ultraviolet Explorer and Hubble Space Telescope satellites, are found to show generally excellent internal consistency and to be in good agreement with the values of T-e and N-e estimated from other line ratios. These results provide observational support for the accuracy of the theoretical ratios and hence the atomic data adopted in their derivation. Theoretical ratios are also presented for the infrared line pair R-4 = I(122 mum)/I(205 mum), and the usefulness of R-4 as an electron density diagnostic is briefly discussed.

A comparison of theoretical MgVI emission line strengths with active-region observations from serts

R-matrix calculations of electron impact excitation rates in N-like Mg vi are used to derive theoretical electron-density-sensitive emission line ratios involving 2s(2)2p(3)-2s2p(4) transitions in the 269-403 Angstrom wavelength range. A comparison of these with observations of a solar active region, obtained during the 1989 flight of the Solar EUV Rocket Telescope and Spectrograph (SERTS), reveals good agreement between theory and observation for the 2s(2)2p(3) S-4-2s2p(4) P-4 transitions at 399.28, 400.67, and 403.30 Angstrom, and the 2s(2)2p(3) P-2-2s2p(4) D-2 lines at 387.77 and 387.97 Angstrom. However, intensities for the other lines attributed to Mg vi in this spectrum by various authors do not match the present theoretical predictions. We argue that these discrepancies are not due to errors in the adopted atomic data, as previously suggested, but rather to observational uncertainties or mis-identifications. Some of the features previously identified as Mg vi lines in the SERTS spectrum, such as 291.36 and 293.15 Angstrom, are judged to be noise, while others (including 349.16 Angstrom) appear to be blended.

Secondary threshold laws for multiple ionization of atoms

We propose a physical mechanism that leads to the emergence of secondary threshold laws in processes of multiple ionization of atoms. We argue that the removal of n electrons (n>2) from a many-electron atom may proceed via intermediate resonant states of the corresponding doubly charged ion. For atoms such as rare gases, the density of such resonances in the vicinity of subsequent ionization thresholds is high. As a result, the appearance energies for multiply charged ions are close to these thresholds, while the effective power indices mu in the near-threshold energy dependence of the cross section, sigmaproportional toE(mu), are lower compared to those from the Wannier theory. This provides a possible explanation of the recent experimental results of B. Gstir [Nucl. Instrum. Methods Phys. Res. B 205, 413 (2003)].

Welfare Regimes and “progressive” governments in Latin America: The cases of Venezuela, Ecuador and Bolivia

Several authors have applied the concept of Welfare Regimens for studying social policy in Latin America (Esping-Andersen, 1993 and 2000). Among others, Martínez Franzoni (2007) develops a typology, with fi eld work is at the turn of the millennium, and establishes three categories: State-productivist regime, state-protectionist and family orientated. Most countries in the region are placed in the latter category. The hypothesis of this article argues that with the emergence of governments considered “left” or “progressive” in several countries of the region from the late ‘90s and, more decisively, in 2000’, the map of welfare regimes models could have mutated substantively. The nationally transformative experiences are different (various socio-economic realities and political action in which they are located exists) but they have several contact points that can be summarized in a greater state intervention in different areas previously closed to their operating and recovery of important functions of welfare and care of the population by the government. The paper discusses with an exploratory and descriptive approach the welfare schemes that would shape in three countries that have constitutionalized the change from the neoliberal paradigm: Venezuela, Bolivia and Ecuador.

Unraveling EU Policies: the ““Common Basic Principles”” and the ““European Integration Fund”” as a technology of government

this paper is about EU “soft policies” on immigrant integration. It analyzes the “Common Basic Principles” (CBPs) and the “European Integration Fund” (EIF), two devices that have been recently established within this framework. It adopts the theoretical perspective of the “anthropology of policy” and “governmentality studies”. It shows the context of birth of the aforementioned devices, as well as their functioning and the assessment done by the actors implied in the elaboration/implementation/evaluation of the related policies. It is based both on documentary research as well as direct observation and interviews done to the actors implied. It concludes that the PBC and the EIF should be considered as a “technology of government”, that strives to align the conduct of the actors with the governmental aims, as well as it produces specific practices and knowledge. It also underlines an intrinsic feature of many policies: their “congenital failure”, since they are (often) disputed and resignified by situated actors, who are embedded in asymmetrical power relations.

Prueba de inmigración y márgenes legales del desencuentro. Políticas públicas, prácticas sociales y construcción de la persona

La redacción de las directrices y los procedimientos administrativos que hacen virtualmente posible la inmigración, contribuye a construir no sólo los itinerarios sino también el imaginario social sobre la alteridad. El principal objetivo del artículo es poner de relieve –mediante el análisis discursivo de las Hojas informativas publicadas en la WEB del Ministerio de Empleo y Seguridad Social- cómo la construcción social del emigrante/inmigrante y el proyecto migratorio topan con unas representaciones y envites, instituidos y refrendados  en y por la propia formulación de la reglamentación, pero no del todo explícitos. Entendiendo el texto como una acción que genera otras acciones, se examinan las consecuencias que tiene sobre la practica social de los inmigrantes. En suma, se trata  de vislumbrar los elementos (terminología, fórmulas, esquemas y prácticas inducidas) que van constituyendo al inmigrante como agente social subordinado a micro-procesos y relaciones que se le escapan en gran parte (en contra de las apariencias que parecieran sugerir lo contrario) y van marcando su propia capacidad de acción. En conclusión y retomando la distinción entre principio de diferencia y principio de indiferencia sugerida por Foucault, se muestra que mientras el primero rige las clausulas generales, el segundo articula las específicas.