NMR and μ+\mu^{+}SR detection of unconventional spin dynamics in Er(trensal) and Dy(trensal) molecular magnets

Measurements of proton Nuclear Magnetic Resonance (1H NMR) spectra and relaxation and of Muon Spin Relaxation ($\mu^{+}$SR) have been performed as a function of temperature and external magnetic field on two isostructural lanthanide complexes, Er(trensal) and Dy(trensal) featuring crystallographically imposed trigonal symmetry. Both the nuclear 1/T1 and muon $\lambda$ longitudinal relaxation rates, LRR, exhibit a peak for temperatures T lower than 30K, associated to the slowing down of the spin dynamics, and the width of the NMR absorption spectra starts to increase significantly at T ca. 50K, a temperature sizably higher than the one of the LRR peaks. The LRR peaks have a field and temperature dependence different from those previously reported for all Molecular Nanomagnets. They do not follow the Bloembergen-Purcell-Pound scaling of the amplitude and position in temperature and field and thus cannot be explained in terms of a single dominating correlation time $\tau$c determined by the spin slowing down at low temperature. Further, for T lower than 50K the spectral width does not follow the temperature behavior of the magnetic susceptibility chi. We suggest, using simple qualitative considerations, that the observed behavior is due to a combination of two different relaxation processes characterized by the correlation times $\tau$LT and $\tau$HT, dominating for T lower than 30K and T higher than 50K, respectively. Finally, the observed flattening of LRR for T lower than 5K is suggested to have a quantum origin

Perceived importance of components of asynchronous music in circuit training

This study examined regular exercisers’ perceptions of specific components of music during circuit training. Twenty-four men (38.8 years, s = 11.8 years) and 31 women (32.4 years, s = 9.6 years) completed two questionnaires immediately after a circuit training class. Participants rated the importance of 13 components of music (rhythm, melody, etc.) in relation to exercise enjoyment, and each completed the Affect Intensity Measure (Larsen, 1984) to measure emotional reactivity. Independent t tests were used to evaluate gender differences in perceptions of musical importance. Pearson correlations were computed to evaluate the relationships between affect intensity, age and importance of musical components. Consistent with previous research and theoretical predictions, rhythm response components (rhythm, tempo, beat) were rated as most important. Women rated the importance of melody significantly higher than did men, while men gave more importance to music associated with sport. Affect intensity was found to be positively and significantly related to the perceived importance of melody, lyrical content, musical style, personal associations and emotional content. Results suggest that exercise leaders need to be sensitive to personal factors when choosing music to accompany exercise. Qualitative research that focuses on the personal meaning of music is encouraged

¿Qué hacer con la violencia?

¿Será posible que algún día dejemos de levantar la bandera por el cese de la violencia?, ¿llegará el día en que podamos, finalmente, dejar de pelear por esto? ¿Será siquiera imaginable la eliminación de la violencia contra las mujeres? Difícilmente podamos contestar afirmativamente a esta pregunta en este presente donde distintos sectores de la sociedad y fuerzas políticas arremeten con fuerza contra los feminismos y sus consignas, que parecen haberse erigido como chivo expiatorio de fuerzas tan reaccionarias como conservadoras. La lucha continúa porque siguen cometiéndose crímenes brutales sobre las mujeres. Cada 25 de noviembre nos recuerda esto: la marca de la violencia como una herida siempre abierta. Una cicatriz que nos despierta y arroja a la memoria. La persistencia de una lucha que parece avanzar al mismo tiempo que convive con numerosas e inagotables manifestaciones de violencia. Repone la latencia de un conflicto que se reabre. Un espectáculo de la crueldad al que parecemos habernos acostumbrado, hasta que irrumpe, una y otra vez, insistente. Una marca que pone de manifiesto nuestra común vulnerabilidad, la imposibilidad de extirpar el dolor, lo que nos obliga irremediablemente a reconocer, tematizar, nombrar, para actuar sobre ella. Es que algo cabe hacer, algo debe hacerse.Fil: Lucaccini, Mirna. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Instituto de Investigaciones "Gino Germani"; Argentin

Lecturas feministas de Julia Kristeva: sobre las formas de la lucha política y el problema que se niega a desaparecer

This article recovers the criticisms that have been made of Julia Kristeva from certain feminisms, especially from the work of Judith Butler and secondarily from Nancy Fraser. For this, some key concepts of Kristeva's thought are recovered in the light of a series of discussions within feminist theory. Firstly, it is possible to situate them in a more general context of reflections within feminism in the contest between the feminism of difference and deconstructivist feminism. On the other hand, although linked to this first point, it is inscribed in a more general debate between feminisms and psychoanalysis, and the latter in its link with a certain post-structuralist thought. In the light of Butler's criticisms of Kristeva, we are interested in shedding light on the terms, concepts and discussions of feminism in which this exchange takes place. Lastly, the above-mentioned journey will make it possible to distinguish what forms the political struggle takes on in both Julia Kristeva and Judith Butler.En este artículo se recuperan las críticas que se le han hecho a Julia Kristeva desde ciertos feminismos, especialmente a partir del trabajo de Judith Butler y secundariamente de Nancy Fraser. Para esto, se reponen algunos conceptos claves del pensamiento de Kristeva, a la luz de una serie de discusiones al interior de la teoría feminista. En primer lugar, es posible ubicarlas en un contexto más general de reflexiones al interior del feminismo en la contienda entre el feminismo de la diferencia y el feminismo deconstructivista. Por otra parte, aunque vinculado a este primer punto, se inscribe en un debate más general de los feminismos con el psicoanálisis y de este último en su vínculo con cierto pensamiento postestructuralista. Nos interesa iluminar, a la luz de las críticas de Butler a esta, en qué términos, conceptos y discusiones del feminismo se inscribe este intercambio. Por último, el recorrido indicado permitirá distinguir qué formas adquiere la lucha política tanto en Julia Kristeva como Judith Butler

Redesign and initial validation of an instrument to assess the motivational qualities of music in exercise: The Brunel Music Rating Inventory-2

In the present study, a measure to assess the motivational qualities of music in exercise was redesigned, extending previous research efforts (Karageorghis et al., 1999). The original measure, the Brunel Music Rating Inventory (BMRI), had shown limitations in its factor structure and its applicability to non-experts in music selection. Redesign of the BMRI used in-depth interviews with eight participants (mean age 31.9 years, s¼8.9 years) to establish the initial item pool, which was examined using a series of confirmatory factor analyses. A single-factor model provided a good fit across three musical selections with different motivational qualities (comparative fit index, CFI: 0.95 – 0.98; standardized root mean residual, SRMR: 0.03 – 0.05). The single-factor model also demonstrated acceptable fit across two independent samples and both sexes using one piece of music (CFI: 0.86 – 1.00; SRMR: 0.04 – 0.07). The BMRI was designed for experts in selecting music for exercise (e.g. dance aerobic instructors), whereas the BMRI-2 can be used both by exercise instructors and participants. The psychometric properties of the BMRI-2 are stronger than those of the BMRI and it is easier to use. The BMRI-2 provides a valid and internally consistent tool by which music can be selected to accompany a bout of exercise or a training session. Furthermore, the BMRI-2 enables researchers to standardize music in experimental protocols involving exercise-related tasks

Relaxation Dynamics and Magnetic Anisotropy in a Low-Symmetry DyIII Complex

The magnetic behaviour of a Dy(LH)3 complex (LH(-) is the anion of 2-hydroxy-N'-[(E)-(2-hydroxy-3-methoxyphenyl)methylidene]benzhydrazide) was analysed in depth from both theoretical and experimental points of view. Cantilever torque magnetometry indicated that the complex has Ising-type anisotropy, and provided two possible directions for the easy axis of anisotropy due to the presence of two magnetically non-equivalent molecules in the crystal. Ab initio calculations confirmed the strong Ising-type anisotropy and disentangled the two possible orientations. The computed results obtained by using ab initio calculations were then used to rationalise the composite dynamic behaviour observed for both pure Dy(III) phase and Y(III) diluted phase, which showed two different relaxation channels in zero and non-zero static magnetic fields. In particular, we showed that the relaxation behaviour at the higher temperature range can be correctly reproduced by using a master matrix approach, which suggests that Orbach relaxation is occurring through a second excited doublet

Magnetic Anisotropy Trends along a Full 4f-Series: The fn+7Effect

[Image: see text] The combined experimental and computational study of the 13 magnetic complexes belonging to the Na[LnDOTA(H(2)O)] (H(4)DOTA = tetraazacyclododecane-N,N′,N″,N‴-tetraacetic acid and Ln = Ce–Yb) family allowed us to identify a new trend: the orientation of the magnetic anisotropy tensors of derivatives differing by seven f electrons practically coincide. We name this trend the f(n+7) effect. Experiments and theory fully agree on the match between the magnetic reference frames (e.g., the easy, intermediate, and hard direction). The shape of the magnetic anisotropy of some couples of ions differing by seven f electrons might seem instead different at first look, but our analysis explains a hidden similarity. We thus pave the way toward a reliable predictivity of the magnetic anisotropy of lanthanide complexes with a consequent reduced need of computational and synthetical efforts. We also offer a way to gain information on ions with a relatively small total angular momentum (i.e., Sm(3+) and Eu(3+)) and on the radioactive Pm(3+), which are difficult to investigate experimentally