Two-stream instability in quasi-one-dimensional Bose-Einstein condensates

We apply a kinetic model to predict the existence of an instability mechanism in elongated Bose-Einstein condensates. Our kinetic description, based on the Wigner formalism, is employed to highlight the existence of unstable Bogoliubov waves that may be excited in the counterpropagation configuration. We identify a dimensionless parameter, the Mach number at T=0, that tunes different regimes of stability. We also estimate the magnitude of the main parameters at which two-stream instability is expected to be observed under typical experimental conditions

Self-assembly of a columnar polymeric calcium phosphinate derived from camphene

(2,2-Dimethylbicyclo[2.2.1] hept-3-ylmethyl)phosphinic acid (RPO₂H₂), readily prepared from camphene and hypophosphorous acid, formed a polymeric calcium salt [{Ca(RPO₂H) ₂ (RPO₂H₂)(H₂O)}n], with both terminal and triply bridging phosphinate groups, and an overall columnar structure with an inorganic core and a pseudo-close-packed sheath of terpene moieties

The impact of repetition mechanics on the adaptations resulting from strength-, hypertrophy- and cluster-type resistance training

Purpose: The purpose of this study was to examine the acute and chronic training responses to strength-, hypertrophy- and cluster-type resistance training. Methods: Thirty four trained males were assigned to a strength (STR: 4 x 6 repetitions, 85% of one repetition maximum, [1RM], 900s total rest), hypertrophy (HYP: 5 x 10 repetitions, 70% 1RM, 360s total rest), cluster 1 (CL-1: 4 x 6/1 repetitions, 85% 1RM, 1400s total rest), and cluster 2 (CL-2: 4 x 6/1 repetitions, 90% 1RM, 1400s total rest) regimens which were performed twice weekly for a 6 week period. Measurements were taken before, during and following the four workouts to investigate the acute training stimulus, whilst similar measurements were employed to examine the training effects before and after the intervention. Results: The improvements in 1RM strength were significantly greater for the STR (12.09 ± 2.75%; p<0.05, d=1.106) and CL-2 (13.20 ± 2.18%; p<0.001, d=0.816) regimens than the HYP regimen (8.13 ± 2.54%, d=0.453). In terms of the acute responses, the STR and CL-2 workouts resulted in greater time under tension (TUT) and impulse generation in individual repetitions than the HYP workout (p<0.05). Furthermore, the STR (+3.65 ± 2.54mmol/L-1) and HYP (+6.02 ± 2.97mmol/L-1) workouts resulted in significantly greater elevations in blood lactate concentration (p<0.001) than the CL-1 and CL-2 workouts. Conclusion: CL regimens produced similar strength improvements to STR regimens even when volume-load was elevated (CL-2). The effectiveness of the STR and CL-2 regimens underlines the importance of high loads and impulse generation for strength development

Coexpression of rat P2X2 and P2X6 subunits in Xenopus oocytes.

Transcripts for P2X(2) and P2X(6) subunits are present in rat CNS and frequently colocalize in the same brainstem nuclei. When rat P2X(2) (rP2X(2)) and rat P2X(6) (rP2X(6)) receptors were expressed individually in Xenopus oocytes and studied under voltage-clamp conditions, only homomeric rP2X(2) receptors were fully functional and gave rise to large inward currents (2-3 microA) to extracellular ATP. Coexpression of rP2X(2) and rP2X(6) subunits in Xenopus oocytes resulted in a heteromeric rP2X(2/6) receptor, which showed a significantly different phenotype from the wild-type rP2X(2) receptor. Differences included reduction in agonist potencies and, in some cases (e.g., Ap(4)A), significant loss of agonist activity. ATP-evoked inward currents were biphasic at the heteromeric rP2X(2/6) receptor, particularly when Zn(2+) ions were present or extracellular pH was lowered. The pH range was narrower for H(+) enhancement of ATP responses at the heteromeric rP2X(2/6) receptor. Also, H(+) ions inhibited ATP responses at low pH levels (<pH 6.3). The pH-dependent blocking activity of suramin was changed at this heteromeric receptor, although the potentiating effect of Zn(2+) on ATP responses was unchanged. Thus, the rP2X(2/6) receptor is a functionally modified P2X(2)-like receptor with a distinct pattern of pH modulation of ATP activation and suramin blockade. Although homomeric P2X(6) receptors function poorly, the P2X(6) subunit can contribute to functional heteromeric P2X channels and may influence the phenotype of native P2X receptors in those cells in which it is expressed

Raman Spectroscopic and Computational Analysis of the Effects of Noncovalent Interactions on DMSO

Dimethyl sulfoxide (DMSO) is a widely used chemical in synthetic chemistry and also has unique and important biological applications. In the pure liquid, DMSO forms chain like structures of alternating sulfur and oxygen atoms due to its high self-association. However, it is known that DMSO/water mixtures form solutions with unique physical characteristics depending on the mole ratio. For instance, at a 1:2 ratio of DMSO/water a eutectic mixture forms with a freezing point of-70 C. Vibrational spectroscopy allows us to study the effects of noncovalent interactions when water and DMSO interact in solution. Spectral shifts can be analyzed in order to give a clearer picture of the structure of DMSO in DMSO/water mixtures and also in solutions with other hydrogen bond donors that cannot form as extensive hydrogen bonded networks. The anomalous properties of DMSO/water mixtures have been the subject of a large number of studies. It has been previously established that the reason for the unique properties of such solutions lies in the formation of strong hydrogen bonds between water and DMSO. Despite the many studies there is still no clear picture of the structure of DMSO in the water mixture. When a DMSO/water mixture is formed there is great increase in temperature of the solution. This suggests a significant perturbation of water’s hydrogen bond network due to interactions with DMSO. Here, the hydrogen bonding geometries of DMSO/water mixtures are studied using Raman spectroscopy and computational chemistry

The affordance-matching hypothesis: how objects guide action understanding and prediction

PubMed ID: 24860468 ESRC ES/J019178/1 One step ahead: prediction of other people’s behavior in healthy and autistic individual

Vlasov simulation in multiple spatial dimensions

A long-standing challenge encountered in modeling plasma dynamics is achieving practical Vlasov equation simulation in multiple spatial dimensions over large length and time scales. While direct multi-dimension Vlasov simulation methods using adaptive mesh methods [J. W. Banks et al., Physics of Plasmas 18, no. 5 (2011): 052102; B. I. Cohen et al., November 10, 2010, http://meetings.aps.org/link/BAPS.2010.DPP.NP9.142] have recently shown promising results, in this paper we present an alternative, the Vlasov Multi Dimensional (VMD) model, that is specifically designed to take advantage of solution properties in regimes when plasma waves are confined to a narrow cone, as may be the case for stimulated Raman scatter in large optic f# laser beams. Perpendicular grid spacing large compared to a Debye length is then possible without instability, enabling an order 10 decrease in required computational resources compared to standard particle in cell (PIC) methods in 2D, with another reduction of that order in 3D. Further advantage compared to PIC methods accrues in regimes where particle noise is an issue. VMD and PIC results in a 2D model of localized Langmuir waves are in qualitative agreement