Possible experimental signature of octupole correlations in the 02+^+_2 states of the actinides

$J^{\pi}$= 0$^+$ states have been investigated in the actinide nucleus ${}^{240}$Pu up to an excitation energy of 3 MeV with a high-resolution (p,t) experiment at $E_{p}$= 24 MeV. To test the recently proposed $J^{\pi}$= 0$^+_2$ double-octupole structure, the phenomenological approach of the spdf-interacting boson model has been chosen. In addition, the total 0$^+$ strength distribution and the $0^+$ strength fragmentation have been compared to the model predictions as well as to the previously studied (p,t) reactions in the actinides. The results suggest that the structure of the 0$^+_2$ states in the actinides might be more complex than the usually discussed pairing isomers. Instead, the octupole degree of freedom might contribute significantly. The signature of two close-lying 0$^+$ states below the 2-quasiparticle energy is presented as a possible manifestation of strong octupole correlations in the structure of the 0$^+_2$ states in the actinides.Comment: 6 pages, 5 figures, published in Phys. Rev. C 88, 041303(R) (2013

Experimental study of excited states of 62{}^{62}Ni via one-neutron (d,p)(d,p) transfer up to the neutron-separation threshold and characteristics of the pygmy dipole resonance states

The degree of collectivity of the Pygmy Dipole Resonance (PDR) is an open question. Recently, Ries {\it et al.} have suggested the onset of the PDR beyond $N=28$ based on the observation of a significant $E1$ strength increase in the Cr isotopes and proposed that the PDR has its origin in a few-nucleon effect. Earlier, Inakura {\it et al.} had predicted by performing systematic calculations using the random-phase approximation (RPA) with the Skyrme functional SkM* that the $E1$ strength of the PDR strongly depends on the position of the Fermi level and that it displays a clear correlation with the occupation of orbits with orbital angular momenta less than $3\hbar$ $(l \leq 2)$. To further investigate the microscopic structures causing the possible formation of a PDR beyond the $N=28$ neutron shell closure, we performed a $^{61}$Ni$(d,p){}^{62}$Ni experiment at the John D. Fox Superconducting Linear Accelerator Laboratory of Florida State University. To determine the angular momentum transfer populating possible $J^{\pi} = 1^-$ states and other excited states of ${}^{62}$Ni, angular distributions and associated single-neutron transfer cross sections were measured with the Super-Enge Split-Pole Spectrograph. A number of $J^{\pi} = 1^-$ states were observed below the neutron-separation threshold after being populated through $l=2$ angular momentum transfers. A comparison to available $(\gamma,\gamma')$ data for ${}^{58,60}$Ni provides evidence that the $B(E1)$ strength shifts further down in energy. The $(d,p)$ data clearly prove that $l=0$ strength, i.e., the neutron $(2p_{3/2})^{-1}(3s_{1/2})^{+1}$ one-particle-one-hole configuration plays only a minor role for $1^-$ states below the neutron-separation threshold in ${}^{62}$Ni.Comment: 15 pages, 8 figures, accepted for publication in Physical Review

Spontanous periodic breathing is associated with sympathetic hyperreactivity and baroreceptor dysfunction in hypertension

OBJECTIVES: Intermittent periods of hypoxemia such as during periodic breathing are associated with hypertension and increased sympathetic activity. In patients with sleep apnea syndrome, hypertension is common. Treating apnea improves hypertension and reduces sympathetic outflow. The aim of the present study was to investigate the phenomenon and mechanisms of spontaneous periodic breathing in patients with hypertension. METHOD: We examined 43 hypertensive patients with untreated hypertension without left-ventricular dysfunction, heart failure or sleep apnea syndrome. Muscle sympathetic nerve activity (MSA), heart rate (HR), blood pressure (BP) and respiration were continuously recorded at rest and during cold-pressor testing. Oxygen and a CO2-enriched gas were used to test central and peripheral chemoreceptors, respectively. Baroreceptor gain was measured using the alpha method. RESULTS: Seven out of 43 patients showed spontaneous periodic breathing while awake. No difference in MSA, HR and BP was seen between patients with and without periodic breathing at rest except the breathing pattern. However, the cold-pressor test caused a larger increase of MSA in patients with periodic breathing (203 +/- 62 vs. 62 +/- 8%, P < 0.0001 by ANOVA), as well as systolic (46 +/- 6 vs. 25 +/- 3 mmHg, P = 0.002) and diastolic BP (26 +/- 5 vs. 12 +/- 1 mmHg, P = 0.004, ANOVA). Baroreceptor gain was markedly higher in patients with periodic breathing. Chemoreceptor sensitivity was comparable. CONCLUSION: Spontaneous periodic breathing is relatively common in patients with hypertension and is associated with greatly enhanced responses to cold-pressor testing. We suggest increased baroreceptor gain and sympathetic outflow as a cause for the oscillatory respiration pattern via barorespiratory coupling

Prolonged low flow reduces reactive hyperemia and augments low flow mediated constriction in the brachial artery independent of the menstrual cycle

© 2013 Rakobowchuk et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Non-invasive forearm ischemia-reperfusion injury and low flow induced vascular dysfunction models provide methods to evaluate vascular function. The role of oestrogen, an endogenous anti-oxidant on recovery from ischemia-reperfusion injury has not been evaluated nor has the impact of prolonged low flow on vascular function been established. Eight healthy women (33610 yr) attended the lab during the follicular, ovulatory and mid-luteal phases of their menstrual cycles. After 30 minutes of rest, brachial artery vascular function was assessed by ultrasound measurements of diameter changes during 5 minutes of forearm ischemia and 3 minutes after. Subsequently, a 20-minute forearm ischemia period was completed. Further, vascular function assessments were completed 15, 30 and 45 minutes into recovery. Flow-mediated dilation, lowflow-mediated constriction, and reactive hyperaemia proximal to the area of ischemia were determined. Flow-mediated dilation was reduced at 15 minutes of recovery but recovered at 30 and 45 minutes (PRE: 7.161.0%, POST15:4.560.6%, POST30:5. 560.7% POST45:5.960.4%, p,0.01). Conversely, low-flow mediated constriction increased (PRE: 21.360.4%, POST15: 23.360.6%, POST30: 22.560.5% POST45: 21.560.12%, p,0.01). Reactive hyperaemia was reduced throughout recovery (p,0.05). Data were unaffected by menstrual phase. Prolonged low flow altered vascular function and may relate as much to increased vasoconstriction as with decreased vasodilation. Reductions in anterograde shear and greater retrograde shear likely modulate the brachial artery response, but the reduced total shear also plays an important role. The data suggest substantial alterations in vascular function proximal to areas of ischemia with potential clinical implications following reperfusion.British Heart Foundation (PG/08/060/25340),a Physiological Society summer studentship to SG, and a Wellcome Trust Vacation Studentship to EP

Chronic treatment with long-acting nifedipine reduces vasoconstriction to endothelin-1 in essential hypertension

Essential hypertension is associated with enhanced biological activity of endothelin-1 (ET-1) and impaired endothelium-dependent vasodilatation. Dihydropyridine calcium antagonists have antioxidant activity in vitro, and they improve endothelial function in vivo. We tested whether calcium antagonists also influence the biological activity of ET-1 in essential hypertensive (EH) patients in the presence and absence of hypercholesterolemia. In 9 healthy subjects (normotensive [NT] subjects, age: 48.3+/-7.6 years; blood pressure: 118+/-8.6/69+/-5.4 mm Hg) and 21 EH subjects (age: 50.0+/-7.8 years; blood pressure: 164.4+/-5.4/103.8+/-4.4 mm Hg), we studied forearm blood flow and its modification induced by intrabrachial administration of ET-1, phenylephrine, acetylcholine, and sodium nitroprusside at baseline and after 24 weeks of treatment with a nifedipine gastrointestinal therapeutic system (30 to 60 mg per day). At baseline, the first dose of ET-1 (0.5 microg/100 mL of forearm tissue per minute) caused a slight vasodilatation in NT but not in EH subjects, whereas the following higher doses caused a comparable dose-dependent vasoconstriction in EH and NT subjects. The effect of acetylcholine was significantly reduced in EH as compared with NT subjects. In contrast, sodium nitroprusside and phenylephrine had similar effects in NT and EH subjects. After chronic treatment with the nifedipine gastrointestinal therapeutic system, the vasoconstrictor effect induced by both ET-1 and phenylephrine was significantly blunted, whereas the response to acetylcholine was significantly increased and the vasodilation to sodium nitroprusside unchanged. Hypercholesterolemic EH subjects showed a further reduced response to acetylcholine compared with normocholesterolemic EH subjects, and the nifedipine gastrointestinal therapeutic system restored the vasodilation to acetylcholine in this subgroup. In conclusion, in EH subjects, chronic treatment with a long-acting dihydropyridine calcium antagonist not only exhibits a blood pressure-lowering effect but also reduces ET-1-induced vasoconstriction and improves endothelium-dependent vasodilation. Those vasculoprotective effects may importantly contribute to a reduction in major clinical events seen during treatment with these compound

Octupole correlations in positive-parity states of rare-earth and actinide nuclei

In this contribution, further evidence of the importance of multiphonon-octupole excitations to describe experimental data in the rare earths and actinides will be presented. First, new results of a (p, t) experiment at the Q3D magnetic spectrograph in Munich will be discussed, which was performed to selectively excite J(pi) = 0(+) states in Pu-240. spd f interacting boson model (IBM) calculations suggest that the previously proposed double-octupole phonon nature of the J(pi) = 0(2)(+) state is not in conflict with its strong (p, t) population. Second, the framework of the IBM has been adopted for the description of experimental observables related to octupole excitations in the rare earths. Here, the IBM is able to describe the signature splitting for positive- and negative-parity states when multi-dipole and multi-octupole bosons are included. The present study might support the idea of octupole-phonon condensation at intermediate spin (J(pi) = 10(+)) leading to the change in yrast structure observed in Nd-146

Octupole correlations in positive-parity states of rare-earth and actinide nuclei

In this contribution, further evidence of the importance of multiphonon-octupole excitations to describe experimental data in the rare earths and actinides will be presented. First, new results of a (p, t) experiment at the Q3D magnetic spectrograph in Munich will be discussed, which was performed to selectively excite J(pi) = 0(+) states in Pu-240. spd f interacting boson model (IBM) calculations suggest that the previously proposed double-octupole phonon nature of the J(pi) = 0(2)(+) state is not in conflict with its strong (p, t) population. Second, the framework of the IBM has been adopted for the description of experimental observables related to octupole excitations in the rare earths. Here, the IBM is able to describe the signature splitting for positive- and negative-parity states when multi-dipole and multi-octupole bosons are included. The present study might support the idea of octupole-phonon condensation at intermediate spin (J(pi) = 10(+)) leading to the change in yrast structure observed in Nd-146

Of autoregressive continuous time model parameters estimation

This article revisits a sequential approach to the estimation of the parameter in a first-order autoregressive model (AR(1)) with continuous time. There is provided a numerical study to get a results of sequential estimations of the parameter in first-order autoregressive model with continuous time and is computed a stopping rule and the optimal time of observations. Also there is provided a comparing analysis of estimation results with using the sequential approach both the optimal time of observations

The {\eta}'-carbon potential at low meson momenta

The production of $\eta^\prime$ mesons in coincidence with forward-going protons has been studied in photon-induced reactions on $^{12}$C and on a liquid hydrogen (LH$_2$) target for incoming photon energies of 1.3-2.6 GeV at the electron accelerator ELSA. The $\eta^\prime$ mesons have been identified via the $\eta^\prime\rightarrow \pi^0 \pi^0\eta \rightarrow 6 \gamma$ decay registered with the CBELSA/TAPS detector system. Coincident protons have been identified in the MiniTAPS BaF$_2$ array at polar angles of $2^{\circ} \le \theta _{p} \le 11^{\circ}$. Under these kinematic constraints the $\eta^\prime$ mesons are produced with relatively low kinetic energy ($\approx$ 150 MeV) since the coincident protons take over most of the momentum of the incident-photon beam. For the C-target this allows the determination of the real part of the $\eta^\prime$-carbon potential at low meson momenta by comparing with collision model calculations of the $\eta^\prime$ kinetic energy distribution and excitation function. Fitting the latter data for $\eta^\prime$ mesons going backwards in the center-of-mass system yields a potential depth of V = $-$(44 $\pm$ 16(stat)$\pm$15(syst)) MeV, consistent with earlier determinations of the potential depth in inclusive measurements for average $\eta^\prime$ momenta of $\approx$ 1.1 GeV/$c$. Within the experimental uncertainties, there is no indication of a momentum dependence of the $\eta^\prime$-carbon potential. The LH$_2$ data, taken as a reference to check the data analysis and the model calculations, provide differential and integral cross sections in good agreement with previous results for $\eta^\prime$ photoproduction off the free proton.Comment: 9 pages, 13 figures. arXiv admin note: text overlap with arXiv:1608.0607

Shared genetic variance between obesity and white matter integrity in Mexican Americans.

peer reviewedObesity is a chronic metabolic disorder that may also lead to reduced white matter integrity, potentially due to shared genetic risk factors. Genetic correlation analyses were conducted in a large cohort of Mexican American families in San Antonio (N = 761, 58% females, ages 18-81 years; 41.3 +/- 14.5) from the Genetics of Brain Structure and Function Study. Shared genetic variance was calculated between measures of adiposity [(body mass index (BMI; kg/m(2)) and waist circumference (WC; in)] and whole-brain and regional measurements of cerebral white matter integrity (fractional anisotropy). Whole-brain average and regional fractional anisotropy values for 10 major white matter tracts were calculated from high angular resolution diffusion tensor imaging data (DTI; 1.7 x 1.7 x 3 mm; 55 directions). Additive genetic factors explained intersubject variance in BMI (heritability, h (2) = 0.58), WC (h (2) = 0.57), and FA (h (2) = 0.49). FA shared significant portions of genetic variance with BMI in the genu (rhoG = -0.25), body (rhoG = -0.30), and splenium (rhoG = -0.26) of the corpus callosum, internal capsule (rhoG = -0.29), and thalamic radiation (rhoG = -0.31) (all p's = 0.043). The strongest evidence of shared variance was between BMI/WC and FA in the superior fronto-occipital fasciculus (rhoG = -0.39, p = 0.020; rhoG = -0.39, p = 0.030), which highlights region-specific variation in neural correlates of obesity. This may suggest that increase in obesity and reduced white matter integrity share common genetic risk factors