Hidden quantum phase transition in Mn1−x_{1-x}Fex_{x}Ge: evidence brought by small-angle neutron scattering

The magnetic system of the Mn$_{1-x}$Fe$_{x}$Ge solid solution is ordered in a spiral spin structure in the whole concentration range of $x \in [0 \div 1]$. The close inspection of the small-angle neutron scattering data reveals the quantum phase transition from the long-range ordered (LRO) to short range ordered (SRO) helical structure upon increase of Fe-concentration at $x \in [0.25 \div 0.4]$. The SRO of the helical structure is identified as a Lorentzian contribution, while LRO is associated with the Gaussian contribution into the scattering profile function. The scenario of the quantum phase transition with $x$ as a driving parameter is similar to the thermal phase transition in pure MnGe. The quantum nature of the SRO is proved by the temperature independent correlation length of the helical structure at low and intermediate temperature ranges with remarkable decrease above certain temperature $T_Q$. We suggest the $x$-dependent modification of the effective Ruderman-Kittel-Kasuya-Yosida exchange interaction within the Heisenberg model of magnetism to explain the quantum critical regime in Mn$_{1-x}$Fe$_{x}$Ge.Comment: 6 pages, 4 figure

Nonlinear growth of firehose and mirror fluctuations in turbulent galaxy-cluster plasmas

In turbulent high-beta astrophysical plasmas (exemplified by the galaxy cluster plasmas), pressure-anisotropy-driven firehose and mirror fluctuations grow nonlinearly to large amplitudes, dB/B ~ 1, on a timescale comparable to the turnover time of the turbulent motions. The principle of their nonlinear evolution is to generate secularly growing small-scale magnetic fluctuations that on average cancel the temporal change in the large-scale magnetic field responsible for the pressure anisotropies. The presence of small-scale magnetic fluctuations may dramatically affect the transport properties and, thereby, the large-scale dynamics of the high-beta astrophysical plasmas.Comment: revtex, 4 pages, 1 figure; replaced to match published versio

Sensitivity as outcome measure of androgen replacement: the AMS scale

BACKGROUND: The capacity of the AMS scale as clinical utility and as outcome measure still needs validation. METHODS: An open post-marketing study was performed by office-based physicians in Germany in 2004. We analysed data of 1670 androgen-deficient males who were treated with testosterone gel. The AMS scale was applied prior to and after 3 months treatment. RESULTS: The improvement of complaints under treatment relative to the baseline score was 30.7% (total score), 27.3% (psychological domain), 30.5% (somatic domain), and 30.7% (sexual domain), respectively. Patients with little or no symptoms before therapy improved by 9%, those with mild complaints at entry by 24%, with moderate by 32%, and with severe symptoms by 39% – compared with the baseline score. We showed that the distribution of complaints of testosterone deficient men before therapy almost returned to norm values after 12 weeks of testosterone treatment. Age, BMI, and total testosterone level at baseline did not modify the positive effect of androgen therapy. We also demonstrated that the AMS results can predict the independent (physician's) opinion about the individual treatment effect. Both, sensitivity (correct prediction of a positive assessment by the physician) and specificity (correct prediction of a negative assessment by the physician) were over 70%, if about 22% improvement of the AMS total score was used as cut-off point. CONCLUSION: The AMS scale showed a convincing ability to measure treatment effects on quality of life across the full range of severity of complaints. Effect modification by other variables at baseline was not observed. In addition, results of the scale can predict the subjective clinical expert opinion on the treatment efficiency

Generation of Magnetic Field by Combined Action of Turbulence and Shear

The feasibility of a mean-field dynamo in nonhelical turbulence with superimposed linear shear is studied numerically in elongated shearing boxes. Exponential growth of magnetic field at scales much larger than the outer scale of the turbulence is found. The charateristic scale of the field is l_B ~ S^{-1/2} and growth rate is gamma ~ S, where S is the shearing rate. This newly discovered shear dynamo effect potentially represents a very generic mechanism for generating large-scale magnetic fields in a broad class of astrophysical systems with spatially coherent mean flows.Comment: 4 pages, 5 figures; replaced with revised version that matches the published PR

Functional interaction of CCAAT/enhancer-binding-protein-α basic region mutants with E2F transcription factors and DNA

The transcription factor CCAAT/enhancer-binding protein {alpha} (C/EBP{alpha}) regulates cell cycle arrest and terminal differentiation of neutrophils and adipocytes. Mutations in the basic leucine zipper domain (bZip) of C/EBP{alpha} are associated with acute myeloid leukemia. A widely used murine transforming C/EBP{alpha} basic region mutant (BRM2) entails two bZip point mutations (I294A/R297A). BRM2 has been discordantly described as defective for DNA binding or defective for interaction with E2F. We have separated the two BRM2 mutations to shed light on the intertwined reciprocity between C/EBP{alpha}-E2F-DNA interactions. Both, C/EBP{alpha} I294A and R297A retain transactivation capacity and interaction with E2F-DP. The C/EBP{alpha} R297A mutation destabilized DNA binding, whereas the C/EBP{alpha} I294A mutation enhanced binding to DNA. The C/EBP{alpha} R297A mutant, like BRM2, displayed enhanced interaction with E2F-DP but failed to repress E2F-dependent transactivation although both mutants were readily suppressed by E2F1 for transcription through C/EBP cis-regulatory sites. In contrast, the DNA binding enhanced C/EBP{alpha} I294A mutant displayed increased repression of E2F-DP mediated transactivation and resisted E2F-DP mediated repression. Thus, the efficient repression of E2F dependent S-phase genes and the activation of differentiation genes reside in the balanced DNA binding capacity of C/EBP{alpha}

Zoneamento de riscos climáticos para o feijoeiro no Estado de Goiás em cenários de aquecimento global.

Entende-se que o delineamento de áreas e períodos mais apropriados ao cultivo do feijoeiro conforme os prognósticos de aumento de temperatura do ar global também é uma linha de pesquisa importante para ser explorada.bitstream/item/25856/1/comt-191.pd