Optical pumping by a laser pulse traveling in a cavity

We have developed a general method to perform optical pumping by a pulsed laser with the aid of an optical cavity ͑cavity-assisted optical pumping͒. Optical pumping is achieved by repetitive interaction of a single laser pulse with a target material in the cavity. This method is demonstrated for manganese ions, Mn + , stored in a linear radio-frequency ion trap; about 10 8 ions are spin polarized by a 5-ns laser pulse via 7 P J ← 7 S 3 ͑J =3 or 4͒ transition in the ultraviolet region. The linewidth of the pulsed light source is broad enough to transfer the populations of lower hyperfine levels to the highest one ͑F =11/ 2͒ in the 7 S 3 ground state; the nuclear spin is polarized as well. DOI: 10.1103/PhysRevA.77.033417 PACS number͑s͒: 32.80.Xx, 32.10.Fn, 37.10.Ty, 37.20.ϩj Optical pumping ͓1͔ is a powerful technique for spin polarization widely used since the first idea of Kastler in 1950 ͓2͔. It is operated by repeated cycles of absorption of circularly polarized light and spontaneous emission back to the initial state. This cycle transfers angular momentum of photons to target atoms. The atoms eventually reach a nonstatistical population distribution, where only one of the magnetic sublevels is populated. Spin-polarized atoms and nuclei thus produced have a variety of applications ͓3-5͔: Highly precise spectroscopy especially with double resonance techniques ͓6,7͔, spin-exchange collisions ͓8͔, manipulation and statecontrol of atoms ͓9͔, sensitive magnetometry ͓10͔, and so forth. Although the advent of tunable lasers greatly expanded the application of optical pumping, the light source has been limited to continuous-wave ͑cw͒ lasers. This is due to the long interaction time needed to repeat the pumping cycles until the spin-polarization process is completed; the time scale is typically longer than several microseconds. Therefore, standard nanosecond laser pulses are not suitable for the light source. Recently, several schemes have been proposed for pulsed lasers to generate spin-polarized atomic ions without relying on optical pumping ͓11͔. The elaborate schemes, however, have been applied only to alkaline-earth elements; the ground-state atoms in 1 S 0 are excited by a circularly polarized laser pulse to 3 P 1 ͑M J = +1͒, and further ionization results in spin-polarized ions in the 2 S 1/2 ground state. The advantage of pulsed lasers over cw ones, particularly in the tunability in short wavelengths, urges us to develop a new method with broader applicability. In this paper, we present "cavity-assisted optical pumping," which allows us to perform optical pumping by a laser pulse with the aid of an optical cavity. It is shown that repeated interaction of a single laser pulse produces highdegree spin polarization of target materials in the cavity. This method provides a general technique for using pulsed lasers in a manner similar to cw light sources. The broad linewidth inherent to pulsed lasers enables nuclear spins to be polarized as well by exciting transitions split by hyperfine structures. In the experiment, we have created a spin-polarized ensemble of about 10 8 ions of manganese, Mn + , stored in a linear ion trap. Mn + has a nuclear and an electron spin of I =5/ 2 and J = 3, respectively, in the ground state ͑ 7 S 3 ͒ with an electronic configuration of 3d 5 4s 1 . We have observed spin polarization of Mn + ions in the highest angular momentum of F = J + I =11/ 2; the ions are forced to populate in the sublevel of the magnetic quantum number M = +11/ 2 by interaction with a laser pulse of + circular polarization

Magnetic nanodoping: Atomic control of spin states in cobalt doped silver clusters

The interaction of magnetic dopants with delocalized electron states can result in interesting many-body physics. Here, the magnetic properties of neutral and charged finite silver metal host clusters with a magnetic cobalt atom impurity were investigated experimentally by exploiting the complementary methods of Stern- Gerlach molecular beam deflection and x-ray magnetic circular dichroism spectroscopy and are accompanied by density functional theory calculations and charge transfer multiplet simulations. The influence of the number of valence electrons and the consequences of impurity encapsulation were addressed in free size-selected, singly cobalt-doped silver clusters CoAg0,n+ (n = 2–15). Encapsulation of the dopant facilitates the formation of delocalized electronic shells with complete hybridization of the impurity 3d- and the host 5s-derived orbitals, which results in impurity valence electron delocalization, effective spin relaxation, and a low-spin ground state. In the exohedral size regime, spin pairing in the free electron gas formed by the silver 5s electrons is the dominating driving force determining the local 3d occupation of the impurity and therefore, adjusting the spin magnetic moment accordingly

Glucagon-like Peptide-1 Suppresses the Proliferation and Migration of Vascular Smooth Muscle Cells: Implications for Preventive Effects on Atherosclerosis

Our group previously demonstrated the suppressive effect of glucagon-like peptide-1 (GLP-1) on macrophage-driven atherosclerosis in apolipoprotein E-deficient (apoE-/-) mice. In the present study we investigated the suppressive effect of GLP-1 on the atherogenic phenotype of vascular smooth muscle cells (VSMCs) in vivo using apoE-/- mice, and the proliferation and migration of human VSMCs in vitro. A 4-week infusion of GLP-1 in 17-week-old apoE-/- mice significantly reduced the proliferative VSMC phenotype stained with SMemb. Platelet-derived growth factor (PDGF) -BB significantly stimulated the proliferation of human aortic VSMCs by three fold. Both 0.1 and 1nmol/l GLP-1 significantly suppressed the PDGF-induced VSMC proliferation, and this suppressive effect was significantly abolished by the GLP-1 receptor antagonist exendin (9-39) (50nmol/l). The GLP-1 receptor agonists liraglutide (100nmol/l) and exendin-4 (100nmol/l) mimicked GLP-1, significantly suppressing PDGF-induced VSMC proliferation. PDGF-BB significantly stimulated the migration of human aortic VSMCs by 1.7 -fold, and this effect was significantly suppressed by 1nmol/l GLP-1. These findings suggest that GLP-1-related treatments may prevent the progression of atherosclerotic lesions by suppressing the proliferation and migration of VSMCs, which are characteristic features of atherosclerosis

Novel Superconducting Phases in Copper Oxides and Iron-oxypnictides: NMR Studies

We reexamine the novel phase diagrams of antiferromagnetism (AFM) and high-Tc$superconductivity (HTSC) for a disorder-free CuO$_2$plane based on an evaluation of local hole density ($p$) by site-selective Cu-NMR studies on multilayered copper oxides. Multilayered systems provide us with the opportunity to research the characteristics of the disorder-free CuO$_2$plane. The site-selective NMR is the best and the only tool used to extract layer-dependent characteristics. Consequently, we have concluded that the uniform mixing of AFM and SC is a general property inherent to a single CuO$_2$plane in an underdoped regime of HTSC. The$T$=0 phase diagram of AFM constructed here is in quantitative agreement with the theories in a strong correlation regime which is unchanged even with mobile holes. This {\it Mott physics} plays a vital role for mediating the Cooper pairs to make$T_c$of HTSC very high. By contrast, we address from extensive NMR studies on electron-doped iron-oxypnictides La1111 compounds that the increase in$T_c$is not due to the development of AFM spin fluctuations, but because the structural parameters, such as the bond angle$\alpha$of the FeAs$_4$tetrahedron and the a-axis length, approach each optimum value. Based on these results, we propose that a stronger correlation in HTSC than in FeAs-based superconductors may make$T_c$ higher significantly.Comment: 5 pages, 4 figures, accepted for publication in J.Phys.Chem.Solids (2010

Nationwide retrospective observational study of idiopathic dendriform pulmonary ossification : clinical features with a progressive phenotype

Background: Diffuse pulmonary ossification is a specific lung condition that is accompanied by underlying diseases. However, idiopathic dendriform pulmonary ossification (IDPO) is extremely rare, and the clinical features remain unclear. In this study, we aimed to report the clinical characteristics of IDPO. Methods: We conducted a nationwide survey of patients with IDPO from 2017 to 2019 in Japan and evaluated the clinical, radiological, and histopathological findings of patients diagnosed with IDPO. Results: Twenty-two cases of IDPO were identified. Most subjects (82%) were male, aged 22-56 years (mean (SD), 37.9 (9.1)) at diagnosis. Nearly 80% of the subjects were asymptomatic, and the condition was discovered during a medical check-up. However, 36% of the subjects showed a decline in forced vital capacity (%FVC) predicted <80% at diagnosis. The typical radiological features of high-resolution CT (HRCT) are calcified branching structures that are predominantly distributed in the lower lung fields without any other conspicuous finding. Histopathological analysis also showed dendriform ossified lesions from the intraluminal areas to interstitial areas. Notably, during the follow-up period of 20 years, disease progression was found in 88% on HRCT and more than 50% on pulmonary function tests (FVC and/or forced expiratory volume in 1s). Two cases with rapid decline of 10% /year in %FVC predicted were observed.)) at diagnosis. Nearly 80% of the subjects were asymptomatic, and the condition was discovered during a medical check-up. However, 36% of the subjects showed a decline in forced vital capacity (%FVC) predicted <80% at diagnosis. The typical radiological features of high-resolution CT (HRCT) are calcified branching structures that are predominantly distributed in the lower lung fields without any other conspicuous finding. Histopathological analysis also showed dendriform ossified lesions from the intraluminal areas to interstitial areas. Notably, during the follow-up period of 20 years, disease progression was found in 88% on HRCT and more than 50% on pulmonary function tests (FVC and/or forced expiratory volume in 1s). Two cases with rapid decline of 10% /year in %FVC predicted were observed. )) at diagnosis. Nearly 80% of the subjects wereasymptomatic, and the condition was discovered during a medical check-up. However, 36% of the subjects showed a decline in forced vital capacity (%FVC) predicted <80% at diagnosis. The typical radiological features of high-resolution CT (HRCT) are calcified branching structures that are predominantly distributed in the lower lung fields without any other conspicuous finding. Histopathological analysis also showed dendriform ossified lesions from the intraluminal areas to interstitial areas. Notably, during the follow-up period of 20 years, disease progression was found in 88% on HRCT and more than 50% on pulmonary function tests (FVC and/or forced expiratory volume in 1s). Two cases with rapid decline of 10% /year in %FVC predicted were observed. Conclusions: IDPO develops at a young age with gradually progressive phenotype. Further research and long-term (>20 years) follow-up are required to clarify the pathogenesis and clinical findings in IDPO

Real-Time Imaging of Rabbit Retina with Retinal Degeneration by Using Spectral-Domain Optical Coherence Tomography

Background: Recently, a transgenic rabbit with rhodopsin Pro 347 Leu mutation was generated as a model of retinitis pigmentosa (RP), which is characterized by a gradual loss of vision due to photoreceptor degeneration. The purpose of the current study is to noninvasively visualize and assess time-dependent changes in the retinal structures of a rabbit model of retinal degeneration by using speckle noise-reduced spectral-domain optical coherence tomography (SD-OCT). Methodology/Principal Findings: Wild type (WT) and RP rabbits (aged 4–20 weeks) were investigated using SD-OCT. The total retinal thickness in RP rabbits decreased with age. The thickness of the outer nuclear layer (ONL) and between the external limiting membrane and Bruch’s membrane (ELM–BM) were reduced in RP rabbits around the visual streak, compared to WT rabbits even at 4 weeks of age, and the differences increased with age. However, inner nuclear layer (INL) thickness in RP rabbits did not differ from that of WT during the observation period. The ganglion cell complex (GCC) thickness in RP rabbits increased near the optic nerve head but not around the visual streak in the later stages of the observation period. Hyper-reflective change was widely observed in the inner segments (IS) and outer segments (OS) of the photoreceptors in the OCT images of RP rabbits. Ultrastructural findings in RP retinas included the appearance of small rhodopsin-containing vesicles scattered in the extracellular space around the photoreceptors

Protein S-guanylation by the biological signal 8-nitroguanosine 3\u27,5\u27-cyclic monophosphate

The signaling pathway of nitric oxide (NO) depends mainly on guanosine 3′,5′-cyclic monophosphate (cGMP, 1). Here we report the formation and chemical biology of a nitrated derivative of cGMP, 8-nitroguanosine 3′,5′-cyclic monophosphate (8-nitro-cGMP, 2), in NO-mediated signal transduction. Immunocytochemistry demonstrated marked 8-nitro-cGMP production in various cultured cells in an NO-dependent manner. This finding was confirmed by HPLC plus electrochemical detection and tandem mass spectrometry. 8-Nitro-cGMP activated cGMP-dependent protein kinase and showed unique redox-active properties independent of cGMP activity. Formation of protein Cys-cGMP adducts by 8-nitro-cGMP was identified as a new post-translational modification, which we call protein S-guanylation. 8-Nitro-cGMP seems to regulate the redox-sensor signaling protein Keap1, via S-guanylation of the highly nucleophilic cysteine sulfhydryls of Keap1. This study reveals 8-nitro-cGMP to be a second messenger of NO and sheds light on new areas of the physiology and chemical biology of signal transduction by NO