Physical Processes at the Surface of the Arctic Tundra

The results of measurements of net total radiation flux and temperatures in the air and surface layers of the tundra and snow near Barrow, Alaska, are presented for the period September 1965 to September 1966. Lowest average monthly temperatures occurred in March, the highest in July. The minimum average net total radiation occurred in January with the maximum in July. The tundra surface began to thaw by 18 June and to freeze by September.Processus physiques à la surface de la toundra arctique. Les auteurs présentent les résultats de mesures du flux de rayonnement total net et des températures dans l'air et dans les niveaux de surface de la toundra et de la neige, près de Barrow, Alaska, pour la période de septembre 1965 à septembre 1966. Les températures mensuelles moyennes minimales se retrouvent en mars, les maximales en juillet. Le minimum de rayonnement total net moyen se produit en janvier, avec un maximum en juillet. La surface de la toundra commence à dégeler vers le 18 juin et à regeler en septembre

Environmental Radiocesium in Subarctic and Arctic Alaska Following Chernobyl

Radiocesium (134Cs and 137Cs) concentrations were measured in soil, plant and wildlife samples from subarctic to arctic Alaska. Concentrations of 137Cs ranged from below detectable or low levels in whale and fish samples to as high as 242 Bq/kg in lichen. For all potential human food items, the radiocesium concentrations measured in this study were below accepted permissible levels for human consumption. Chernobyl-derived radiocesium concentrations ranged from below detectable or low levels in all arctic samples (soil, sediment, lichen, whale, fish and caribou) to 32 Bq/kg in subarctic moss. Therefore the distribution and subsequent deposition of Chernobyl-derived radiocesium appears to be variable but decreasing significantly from the Subarctic (Fairbanks) to the Arctic. The present data support the suggestion that Chernobyl-derived debris arrived from western Canada into central Alaska and subsequently moved to the north (arctic) and to the west, decreasing in the quantity deposited as the debris transversed the state.Key words: Chemobyl, radiocesium, lichen, mushroom, caribou, reindeer, soil, fallout, depositionMots clés: Chernobyl, césium radioactif, lichen, champignon, caribou, renne, sol, retombées, dépô

Constrained dogleg methods for nonlinear systems with simple bounds

We focus on the numerical solution of medium scale bound-constrained systems of nonlinear equations. In this context, we consider an affine-scaling trust region approach that allows a great flexibility in choosing the scaling matrix used to handle the bounds. The method is based on a dogleg procedure tailored for constrained problems and so, it is named Constrained Dogleg method. It generates only strictly feasible iterates. Global and locally fast convergence is ensured under standard assumptions. The method has been implemented in the Matlab solver CoDoSol that supports several diagonal scalings in both spherical and elliptical trust region frameworks. We give a brief account of CoDoSol and report on the computational experience performed on a number of representative test problem

Identity and integration of Russian speakers in the Baltic states: a framework for analysis

Following a review of current scholarship on identity and integration patterns of Russian speakers in the Baltic states, this article proposes an analytical framework to help understand current trends. Rogers Brubaker's widely employed triadic nexus is expanded to demonstrate why a form of Russian-speaking identity has been emerging, but has failed to become fully consolidated, and why significant integration has occurred structurally but not identificationally. By enumerating the subfields of political, economic, and cultural ‘stances’ and ‘representations’ the model helps to understand the complicated integration processes of minority groups that possess complex relationships with ‘external homelands’, ‘nationalizing states’ and ‘international organizations’. Ultimately, it is argued that socio-economic factors largely reduce the capacity for a consolidated identity; political factors have a moderate tendency to reduce this capacity, whereas cultural factors generally increase the potential for a consolidated group identity

Qualidade de Vida e Atitudes dos Idosos Face à Velhice

A problemática do envelhecimento tem assumido, nos últimos anos, uma crescente importância na consciência coletiva da população, tornando-se cada vez mais importante compreender a população idosa e a sua realidade. Posto isto, foi realizado um estudo quantitativo e correlacional, que teve como objectivo avaliar a qualidade de vida e atitudes face à velhice de idosos, bem como a relação entre estas e as variáveis sociodemográficas e familiares. Foram inquiridos 100 idosos, com mais de 65 anos e sem deficit cognitivo . Para a recolha de dados utilizou-se uma entrevista estruturada, constituída dados sóciodemográficos do idoso, WHOQOL-AGE (Caballero, Miret, Power, Chatterji, Tobiasz-Adamczyk, Koskinen, Leonardi, Olaya, Haro &Ayuso-Mateos, 2013) e o AAQ ( Laidlaw, Power, Schmidt and the WHOQOL-OLD Group, 2007). Dos resultados destacamos os seguintes: A amostra é constituída por 52% de idosos do sexo masculino tendo uma média de idades de 74,7 (DP=6,8). È no fator Perdas Psicossociais e no Desenvolvimento Psicológico que os idosos têm uma melhor atitude face ao envelhecimento. É no item “Tem dinheiro suficiente para satisfazer as suas necessidades?” que os idosos apresentam uma menor qualidade de vida. Não ter doença diagnosticada e ser do sexo masculino permitem ter melhores atitudes face ao envelhecimento. A Qualidade de Vida está relacionada com a idade, com o estado de saúde e com a intensidade de preocupação da família. Constatou-se que os idosos que não estão institucionalizados apresentam uma melhor qualidade de vida e uma melhor atitude face à velhice. Quem não precisa de ajudas técnicas para se movimentar apresenta uma melhor qualidade de vida. Diferenças nas atitudes face ao envelhecimento consoante a residência onde habita são significativas nas mudanças físicas e no desenvolvimento psicológico sendo que os idosos que não vivem em lares têm uma atitude mais positiva em ambos os fatores. / Over the past few years the issue of aging has played a growing importance in the population`s collective consciousness becoming increasingly important to understand the elderly population and this reality. Therefore a quantitative correlational study was performed to assess the quality of life of seniors and their attitudes towards old age, and the relationship between these and the socio-demographic and family factors. 100 seniors with more than 65 years and without cognitive deficit were surveyed. For data collection we used a structured interview consisting of sociodemographic data of the elderly, WHOQOL-AGE (Caballero Miret Power Chatterji Tobiasz-Adamczyk Koskinen Leonardi Olaya Ayuso-Mateos & Haro 2013) and AAQ (Laidlaw Power Schmidt and the WHOQOL-OLD Group 2007). We highlight: The sample is composed of 52% of males with a mean age of 74.7 (SD = 6.8). It is in the factor Psychosocial Losses and Psychological Development that elderly people have a better attitude towards aging. It is in the item "Do you have enough money to meet your needs?" that seniors show less quality of life. Not having illness and being male allows having better attitudes towards aging. Quality of Life is related to age, health condition and the intensity of family concerns. It was observed that the elderly who are not institutionalized have a better quality of life and a better attitude towards old age. Who does not need assistive devices to move around has a better quality of life. Differences in attitudes towards aging, according to residency, are significant in physical changes and psychological development, thus verifying that elderly who do not live in nursing homes have a more positive attitude in both factors

A Kinematically Complete Measurement of the Proton Structure Function F2 in the Resonance Region and Evaluation of Its Moments

We measured the inclusive electron-proton cross section in the nucleon resonance region (W < 2.5 GeV) at momentum transfers Q**2 below 4.5 (GeV/c)**2 with the CLAS detector. The large acceptance of CLAS allowed for the first time the measurement of the cross section in a large, contiguous two-dimensional range of Q**2 and x, making it possible to perform an integration of the data at fixed Q**2 over the whole significant x-interval. From these data we extracted the structure function F2 and, by including other world data, we studied the Q**2 evolution of its moments, Mn(Q**2), in order to estimate higher twist contributions. The small statistical and systematic uncertainties of the CLAS data allow a precise extraction of the higher twists and demand significant improvements in theoretical predictions for a meaningful comparison with new experimental results.Comment: revtex4 18 pp., 12 figure

Observation of exclusive DVCS in polarized electron beam asymmetry measurements

We report the first results of the beam spin asymmetry measured in the reaction e + p -> e + p + gamma at a beam energy of 4.25 GeV. A large asymmetry with a sin(phi) modulation is observed, as predicted for the interference term of Deeply Virtual Compton Scattering and the Bethe-Heitler process. The amplitude of this modulation is alpha = 0.202 +/- 0.028. In leading-order and leading-twist pQCD, the alpha is directly proportional to the imaginary part of the DVCS amplitude.Comment: 6 pages, 5 figure

Q2Q^2 Dependence of Quadrupole Strength in the γ∗p→Δ+(1232)→pπ0\gamma^*p\to\Delta^+(1232)\to p \pi^0 Transition

Models of baryon structure predict a small quadrupole deformation of the nucleon due to residual tensor forces between quarks or distortions from the pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through the $Q^2$ dependence of the magnetic ($M_{1+}$), electric ($E_{1+}$), and scalar ($S_{1+}$) multipoles in the $\gamma^* p \to \Delta^+ \to p \pi^0$ transition. We report new experimental values for the ratios $E_{1+}/M_{1+}$ and $S_{1+}/M_{1+}$ over the range $Q^2$= 0.4-1.8 GeV$^2$, extracted from precision $p(e,e 'p)\pi^{\circ}$ data using a truncated multipole expansion. Results are best described by recent unitary models in which the pion cloud plays a dominant role.Comment: 5 pages, 5 figures, 1 table. To be published in Phys. Rev. Lett. (References, figures and table updated, minor changes.

Measurement of the Polarized Structure Function σLT′\sigma_{LT^\prime} for p(e⃗,e′π+)np(\vec{e},e'\pi^+)n in the Δ(1232)\Delta(1232) Resonance Region

The polarized longitudinal-transverse structure function $\sigma_{LT^\prime}$ has been measured using the $p(\vec e,e'\pi^+)n$ reaction in the $\Delta(1232)$ resonance region at $Q^2=0.40$ and 0.65 GeV$^2$. No previous $\sigma_{LT^\prime}$ data exist for this reaction channel. The kinematically complete experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS) using longitudinally polarized electrons at an energy of 1.515 GeV. A partial wave analysis of the data shows generally better agreement with recent phenomenological models of pion electroproduction compared to the previously measured $\pi^0 p$ channel. A fit to both $\pi^0 p$ and $\pi^+ n$ channels using a unitary isobar model suggests the unitarized Born terms provide a consistent description of the non-resonant background. The $t$-channel pion pole term is important in the $\pi^0 p$ channel through a rescattering correction, which could be model-dependent.Comment: 6 pages, LaTex, 5 eps figures: Submitted to PRC/Brief Reports v2: Updated referenc

Green function techniques in the treatment of quantum transport at the molecular scale

The theoretical investigation of charge (and spin) transport at nanometer length scales requires the use of advanced and powerful techniques able to deal with the dynamical properties of the relevant physical systems, to explicitly include out-of-equilibrium situations typical for electrical/heat transport as well as to take into account interaction effects in a systematic way. Equilibrium Green function techniques and their extension to non-equilibrium situations via the Keldysh formalism build one of the pillars of current state-of-the-art approaches to quantum transport which have been implemented in both model Hamiltonian formulations and first-principle methodologies. We offer a tutorial overview of the applications of Green functions to deal with some fundamental aspects of charge transport at the nanoscale, mainly focusing on applications to model Hamiltonian formulations.Comment: Tutorial review, LaTeX, 129 pages, 41 figures, 300 references, submitted to Springer series "Lecture Notes in Physics