Magnetic and structural quantum phase transitions in CeCu6-xAux are independent

The heavy-fermion compound CeCu$_{6-x}$Au$_x$ has become a model system for unconventional magnetic quantum criticality. For small Au concentrations $0 \leq x < 0.16$, the compound undergoes a structural transition from orthorhombic to monoclinic crystal symmetry at a temperature $T_{s}$ with $T_{s} \rightarrow 0$ for $x \approx 0.15$. Antiferromagnetic order sets in close to $x \approx 0.1$. To shed light on the interplay between quantum critical magnetic and structural fluctuations we performed neutron-scattering and thermodynamic measurements on samples with $0 \leq x\leq 0.3$. The resulting phase diagram shows that the antiferromagnetic and monoclinic phase coexist in a tiny Au concentration range between $x\approx 0.1$ and $0.15$. The application of hydrostatic and chemical pressure allows to clearly separate the transitions from each other and to explore a possible effect of the structural transition on the magnetic quantum critical behavior. Our measurements demonstrate that at low temperatures the unconventional quantum criticality exclusively arises from magnetic fluctuations and is not affected by the monoclinic distortion.Comment: 5 pages, 3 figure

Measurement of nuclear effects in neutrino interactions with minimal dependence on neutrino energy

We present a phenomenological study of nuclear effects in neutrino charged-current interactions, using transverse kinematic imbalances in exclusive measurements. Novel observables with minimal dependence on neutrino energy are proposed to study quasielastic scattering, and especially resonance production. They should be able to provide direct constraints on nuclear effects in neutrino- and antineutrino-nucleus interactions.Comment: 7 pages, 9 figures, accepted version by PR

Time evolution of stimulated Raman scattering and two-plasmon decay at laser intensities relevant for shock ignition in a hot plasma

Laser–plasma interaction (LPI) at intensities 1015–1016 W cm2 is dominated by parametric instabilities which can be responsible for a significant amount of non-collisional absorption and generate large fluxes of high-energy nonthermal electrons. Such a regime is of paramount importance for inertial confinement fusion (ICF) and in particular for the shock ignition scheme. In this paper we report on an experiment carried out at the Prague Asterix Laser System (PALS) facility to investigate the extent and time history of stimulated Raman scattering (SRS) and two-plasmon decay (TPD) instabilities, driven by the interaction of an infrared laser pulse at an intensity 1:2 1016 W cm2 with a 100 mm scalelength plasma produced from irradiation of a flat plastic target. The laser pulse duration (300 ps) and the high value of plasma temperature (4 keV) expected from hydrodynamic simulations make these results interesting for a deeper understanding of LPI in shock ignition conditions. Experimental results show that absolute TPD/SRS, driven at a quarter of the critical density, and convective SRS, driven at lower plasma densities, are well separated in time, with absolute instabilities driven at early times of interaction and convective backward SRS emerging at the laser peak and persisting all over the tail of the pulse. Side-scattering SRS, driven at low plasma densities, is also clearly observed. Experimental results are compared to fully kinetic large-scale, two-dimensional simulations. Particle-in-cell results, beyond reproducing the framework delineated by the experimental measurements, reveal the importance of filamentation instability in ruling the onset of SRS and stimulated Brillouin scattering instabilities and confirm the crucial role of collisionless absorption in the LPI energy balance

Positronium reflection and positronium beams

Specular reflection of positronium, Ps was observed and that there is adequate intensity at higher energies to make further study worthwhile was established. The scattering appears to be restricted to the outermost surface with a mean free path of (0.75 + or - 0.15)A for Ps in LiF(100). With a greater intensity Ps beam one should see higher order diffraction beams as the result of the periodicity of the surface. Ps diffraction thus offers the possibility of being a novel and valuable probe to study the outermost surface and to study adsorbants on it. Two methods for producing Ps beams are described

Metaphoric coherence: Distinguishing verbal metaphor from `anomaly\u27

Theories and computational models of metaphor comprehension generally circumvent the question of metaphor versus “anomaly” in favor of a treatment of metaphor versus literal language. Making the distinction between metaphoric and “anomalous” expressions is subject to wide variation in judgment, yet humans agree that some potentially metaphoric expressions are much more comprehensible than others. In the context of a program which interprets simple isolated sentences that are potential instances of cross‐modal and other verbal metaphor, I consider some possible coherence criteria which must be satisfied for an expression to be “conceivable” metaphorically. Metaphoric constraints on object nominals are represented as abstracted or extended along with the invariant structural components of the verb meaning in a metaphor. This approach distinguishes what is preserved in metaphoric extension from that which is “violated”, thus referring to both “similarity” and “dissimilarity” views of metaphor. The role and potential limits of represented abstracted properties and constraints is discussed as they relate to the recognition of incoherent semantic combinations and the rejection or adjustment of metaphoric interpretations

Nutrição mineral do Panicum maximum cv. Makueni I: cresimento, concentração e extração dos macronutrientes

Makueni being a promissing specie for Brazilian cattle raising, the present work was carried out to determine weight of dry matter production, concentration and accumulation of macronutrients from 30 days after cutting the grass up to 180 days old. For the purpose and area comprising 600 m² of Latossolo Vermelho Amarelo (Oxisol) at São Carlos, State of São Paulo, Brazil on the farm Canchim, research institute wich belongs to EMBRAPA, the trial was conducted the meadow was cut and fertilized with ammonium sulphate at the rate of 250 kg/ha. At intervals of 30 days after the cutting up to 180 days plants corresponding to one square metre were collected. The dry matter content was determided and the material was analysed for N, P, K, Ca, Mg and S. The maximum production of dry matter is checked at 120 days represented by 1,425 kg/ha. The fasted dry matter production occur around the 60 days after cutting the meadow. The concentration of N is higt at the 30 days (1.62%) and low at the 120 days (0.72%). The concentration of P is highest at the 120 days (0.87%) and lowest at the 60 days (0.003%). The concentration of K is linear with the age of the grass. The concentrations of K change from 2.8% at the begining to 0.76% after 180 days. The concentration of Ca is highest at the 90 days (0.53%). There are not variation in the concentration of Mg in function with the age of the grass. The concentration of S chang of 0,14% at the 30 days for a lowest at the 120 days (0.07%). The accumulation of P, K, Ca is highest at the 90 days. The accumulation of Mg is highest at the 120 days and S accumuled the highest amounts at the 60 days. The greatest amounts of nutrients content in 1.425 kg/ha of dry matter obey the following order: K - 30.4 kg; N - 13-9 kg; Ca - 7-0 kg; Mg - 6.3 kg; S - 1.3 kg; P - 1.2 kg.O trabalho foi conduzido em área de pasto já formado e rebaixado, situado na Fazenda Canchim (UEPAE de São Carlos -EMBRAPA), São Carlos, SP, em Latossolo Vermelho Amarelo, fase arenosa. Com a finalidade de avaliar o crescimento, através da produção de matéria seca, a concentração e acúmulo de macronutriena partir dos 30 dias após o rebaixamento até aos 180 dias. A área foi adubada com nitrogênio correspondendo à 250 kg de sulfato de amônio por hectare. Em intervalos de 30 dias após o rebaixamento até aos 180 dias, foram coletadas quatro metros quadrados das plantas ao acaso, sem subdividir em folhas e caules. O material seca à 80°C, e analisado para N, P, K, Ca, Mg, S. A concentração de nitrogênio é máxima aos 30 dias com 1,62% e mínima aos 120 dias com 0,72%. A concentração de fósforo é máxima aos 180 dias com 0,87% e mínima aos 60 dias com 0,003%. A concentração de potássio é linear com as idades variando de 2,8% a 0,76% aos 180 dias. A concentração de cálcio é máxima aos 90 dias com 0,53%. Não há variação na concentração de magnésio em função da idade da planta. A concentração de enxofre varia de 0,14% aos 30 dias para um mínimo aos 120 dias com 0,07%. O acúmulo de fósforo, potássio, cálcio é máximo aos 90 dias. 0 acúmulo de magnésio é máximo aos 120 dias O acúmulo de enxofre é máximo aos 60 dias. A exportação de macronutrientes contida na produção máxima de 1425 kg de matéria seca por hectare obedece á seguinte ordem: potássio-30,4; nitrogênio -13,9 kg; cálcio-7,0 kg; magnésio-6,3kg; enxofre-1,3 kg; fósforo-1,2 kg

Ultracold neutrons, quantum effects of gravity and the Weak Equivalence Principle

We consider an extension of the recent experiment with ultracold neutrons and the quantization of its vertical motion in order to test the Weak Equivalence Principle. We show that an improvement on the energy resolution of the experiment may allow to establish a modest limit to the Weak Equivalence Principle and on the gravitational screening constant. We also discuss the influence of a possible new interaction of Nature.Comment: Revtex4, 4 pages. Discussion on the equivalence principle altered. Bound is improve

Rotational covariance and light-front current matrix elements

Light-front current matrix elements for elastic scattering from hadrons with spin~1 or greater must satisfy a nontrivial constraint associated with the requirement of rotational covariance for the current operator. Using a model $\rho$ meson as a prototype for hadronic quark models, this constraint and its implications are studied at both low and high momentum transfers. In the kinematic region appropriate for asymptotic QCD, helicity rules, together with the rotational covariance condition, yield an additional relation between the light-front current matrix elements.Comment: 16 pages, [no number