| 1. |
- Bertolino, Mattias, et al.
(author)
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Thomas-Reiche-Kuhn correction for truncated configuration-interaction spaces : Case of laser-assisted dynamical interference
- 2022
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In: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 106:4
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Journal article (peer-reviewed)abstract
- The Thomas-Reiche-Kuhn sum rule is used to form an effective potential that is added to the time-dependent configuration-interaction singles (TDCIS) equations of motion in velocity gauge. The purpose of the effective potential is to include virtual coupling from singles to doubles, which is required for size-consistent velocity-gauge TDCIS results. The proposed method is compared to length-gauge TDCIS results for laser-assisted photoionization. Finally, a dynamical interference effect controlled by two-color fields is predicted for atomic targets.
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| 2. |
- Carlström, Stefanos, et al.
(author)
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General time-dependent configuration-interaction singles. II. Atomic case
- 2022
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In: Physical Review A. - 2469-9926. ; 106:4
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Journal article (peer-reviewed)abstract
- We present a specialization of the grid-based implementation of the time-dependent configuration-interaction singles described in the preceding paper [S. Carlström et al., preceding paper, Phys. Rev. A 106, 043104 (2022)]10.1103/PhysRevA.106.043104. to the case of spherical symmetry. We describe the intricate time propagator in detail and conclude with a few example calculations. Among these, of note are high-resolution photoelectron spectra in the vicinity of the Fano resonances in photoionization of neon and spin-polarized photoelectrons from xenon, in agreement with recent experiments.
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| 3. |
- Jeddi, Sajad, et al.
(author)
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Hydrogen sulfide potentiates the protective effects of nitrite against myocardial ischemia-reperfusion injury in type 2 diabetic rats
- 2022
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In: Nitric Oxide - Biology and Chemistry. - : Elsevier BV. - 1089-8603 .- 1089-8611. ; 124, s. 15-23
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Journal article (peer-reviewed)abstract
- Decreased heart levels of nitric oxide (NO) and hydrogen sulfide (H2S) in type 2 diabetes (T2D) are associated with a higher risk of mortality following ischemia-reperfusion (IR) injury. This study aimed to determine the effects of co-administration of sodium nitrite and sodium hydrosulfide (NaSH) on IR injury in the isolated heart from rats with T2D. Two-month-old male rats were divided into 5 groups (n = 7/group): Control, T2D, T2D + nitrite, T2D + NaSH, and T2D + nitrite + NaSH. T2D was induced using a high-fat diet and a single low dose streptozotocin (30 mg/kg) in intraperitoneal injection. Nitrite (50 mg/L in drinking water) and NaSH (0.28 mg/kg, daily intraperitoneal injection) were administrated for 9 weeks. At the end of the study, hemodynamic parameters were recorded, and infarct size and mRNA expression of H2S- and NO-producing enzymes were measured in the isolated hearts. Nitrite administration to rats with T2D improved recovery of left ventricular developed pressure (LVDP) and the peak rates of positive and negative changes in LV pressure (±dp/dt) by 30%, 17%, and 7.9%, respectively, and decreased infarct size by 18.4%. Co-administration of nitrite and NaSH resulted in further improve in recovery of LVDP, +dp/dt, and –dp/dt by 8.3% (P = 0.0478), 8.4% (P = 0.0085), and 9.0% (P = 0.0004), respectively, and also further decrease in infarct size by 24% (P = 0.0473). Nitrite treatment decreased inducible and neuronal NO synthases (iNOS, 0.4-fold; nNOS, 0.4-fold) and cystathionine β-synthase (CBS, 0.1-fold) expression in the isolated heart from rats with T2D. Co-administration of nitrite and NaSH further increased cystathionine γ-lyase (CSE, 2.8-fold) and endothelial NOS (eNOS, 2.0-fold) expression and further decreased iNOS (0.4-fold) expression. In conclusion, NaSH at a low dose potentiates the favorable effects of inorganic nitrite against myocardial IR injury in a rat model of T2D. These anti-ischemic effects, following co-administration of nitrite and NaSH, were associated with higher CSE-derived H2S and eNOS-derived NO as well as lower iNOS-derived NO in the diabetic hearts.
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| 4. |
- Jeddi, Sajad, et al.
(author)
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Long-term co-administration of sodium nitrite and sodium hydrosulfide inhibits hepatic gluconeogenesis in male type 2 diabetic rats : Role of PI3K-Akt-eNOS pathway
- 2021
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In: Life Sciences. - : Elsevier BV. - 0024-3205 .- 1879-0631. ; 265
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Journal article (peer-reviewed)abstract
- Objective: A deficiency in hydrogen sulfide (H2S) and nitric oxide (NO) contributes to the development of type 2 diabetes (T2D). An inhibitory effect on liver gluconeogenesis has been reported in rats with T2D with co-administration of sodium nitrite and sodium hydrosulfide (NaSH); the underlying mechanisms have however not yet been elucidated. The aim of this study is to determine the long-term effects of co-administering sodium nitrite and NaSH on expression of genes involved in liver gluconeogenesis in rats with T2D. Methods: T2D was induced using a high fat diet combined with low-dose of streptozotocin (30 mg/kg). Rats were divided into 5 groups (n = 7/group): Control, T2D, T2D + nitrite, T2D + NaSH, and T2D + nitrite+NaSH. Nitrite (50 mg/L) and NaSH (0.28 mg/kg) were administered for 9 weeks. Intraperitoneal pyruvate tolerance test (PTT) was performed at the end of the ninth week and mRNA expressions of PI3K, Akt, eNOS, PEPCK, G6Pase, and FBPase were measured in the liver. Results: Co-administration of nitrite and NaSH decreased elevated serum glucose concentrations during PTT. Compared to T2D + nitrite, co-administration of nitrite and NaSH resulted in significant increases in mRNA expression of PI3K, Akt, and eNOS and significant decreases in mRNA expression of G6Pase and FBPase but had no effect on PEPCK expression. Conclusion: Long-term NaSH administration at low-dose, potentiated the inhibitory effects of nitrite on mRNA expression of key liver gluconeogenic enzymes in rats with T2D. This inhibitory effect of nitrite and NaSH co-administration on gluconeogenesis were associated with increased gene expression of PI3K, Akt, and eNOS in the liver.
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| 5. |
- Jeddi, Sajad, et al.
(author)
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Protective effect of intermediate doses of hydrogen sulfide against myocardial ischemia-reperfusion injury in obese type 2 diabetic rats
- 2020
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In: Life Sciences. - : Elsevier BV. - 0024-3205 .- 1879-0631. ; 256
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Journal article (peer-reviewed)abstract
- Objective: Subjects with type 2 diabetes (T2D) have lower circulating hydrogen sulfide (H2S) levels following myocardial ischemia and a higher risk of mortality. The aim of this study was to determine the dose-dependent favorable effects of sodium hydrosulfide (NaSH) on myocardial ischemia-reperfusion (IR) injury in rats with T2D. Methods: T2D was induced using a high-fat diet (HFD) and low-dose of streptozotocin. Rats were divided into control, T2D, and T2D + NaSH groups. NaSH (0.28, 0.56, 1.6, 2.8, and 5.6 mg/kg) was administered intraperitoneally for 9 weeks. At the end of the study, heart from all rats were isolated and left ventricular developed pressure (LVDP) and the peak rates of positive and negative changes in LV pressure (±dp/dt) were recorded during baseline and following myocardial IR injury. In addition, infarct size as well as mRNA expression of H2S- and nitric oxide (NO)-producing enzymes were measured. Results: In diabetic rats, NaSH only at doses of 0.56 and 1.6 mg/kg increased recovery of LVDP (16% and 42%), +dp/dt (25% and 35%) and –dp/dt (23% and 32%) as well as decreased infarct size (44% and 35%). At these doses, NaSH increased expressions of cystathionine γ-lyase (CSE) (440% and 271%) and endothelial NO synthase (eNOS) (232% and 148%) but it decreased the expressions of inducible NOS (iNOS) (55% and 71%). NaSH at 0.28, 2.8 and 5.6 mg/kg had no significant effects on these parameters. Conclusion: NaSH had a bell-shaped cardioprotective effect against myocardial IR injury in rats with T2D. Higher tolerance to IR injury in heart isolated from type 2 diabetic rats treated with intermediate doses of NaSH is associated with higher CSE-derived H2S and eNOS-derived NO as well as lower iNOS-derived NO.
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| 6. |
- Manti, Maria, et al.
(author)
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Maternal androgen excess induces cardiac hypertrophy and left ventricular dysfunction in female mice offspring.
- 2020
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In: Cardiovascular research. - : Oxford University Press (OUP). - 1755-3245 .- 0008-6363. ; 116:3, s. 619-632
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Journal article (peer-reviewed)abstract
- Polycystic ovary syndrome (PCOS) is a common endocrinopathy that is suggested to increase the risk for cardiovascular disease. How PCOS may lead to adverse cardiac outcomes is unclear and here we hypothesized that prenatal exposure to dihydrotestosterone (DHT) and/or maternal obesity in mice induce adverse metabolic and cardiac programming in female offspring that resemble the reproductive features of the syndrome.The maternal obese PCOS phenotype was induced in mice by chronic high-fat-high-sucrose consumption together with prenatal DHT exposure. The prenatally androgenized (PNA) female offspring displayed cardiac hypertrophy during adulthood, an outcome that was not accompanied by aberrant metabolic profile. The expression of key genes involved in cardiac hypertrophy was up-regulated in the PNA offspring, with limited or no impact of maternal obesity. Furthermore, the activity of NADPH oxidase, a major source of reactive oxygen species in the cardiovascular system, was down-regulated in the PNA offspring heart. We next explored for early transcriptional changes in the heart of newly born PNA offspring, which could account for the long-lasting changes observed in adulthood. Neonatal PNA hearts displayed an up-regulation of transcription factors involved in cardiac hypertrophic remodelling and of the calcium-handling gene, Slc8a2. Finally, to determine the specific role of androgens in cardiovascular function, female mice were continuously exposed to DHT from pre-puberty to adulthood, with or without the antiandrogen flutamide. Continuous exposure to DHT led to adverse left ventricular remodelling, and increased vasocontractile responses, while treatment with flutamide partly alleviated these effects.Taken together, our results indicate that intrauterine androgen exposure programmes long-lasting heart remodelling in female mouse offspring that is linked to left ventricular hypertrophy and highlight the potential risk of developing cardiac dysfunction in daughters of mothers with PCOS.
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| 7. |
- Moretti, Chiara H., et al.
(author)
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Dietary nitrite extends lifespan and prevents age-related locomotor decline in the fruit fly
- 2020
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In: Free Radical Biology & Medicine. - : Elsevier BV. - 0891-5849 .- 1873-4596. ; 160, s. 860-870
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Journal article (peer-reviewed)abstract
- Aging is associated with decreased nitric oxide (NO) bioavailability and signalling. Boosting of a dietary nitrate nitrite-NO pathway e.g. by ingestion of leafy green vegetables, improves cardiometabolic function, mitochondrial efficiency and reduces oxidative stress in humans and rodents, making dietary nitrate and nitrite an appealing intervention to address age-related disorders. On the other hand, these anions have long been implicated in detrimental health effects of our diet, particularly in formation of carcinogenic nitrosamines.The aim of this study was to assess whether inorganic nitrite affects lifespan in Drosophila melanogaster and investigate possible mechanisms underlying any such effect.In a survival assay, female flies fed a nitrite supplemented diet showed lifespan extension by 9 and 15% with 0.1 and 1 mu M nitrite respectively, with no impact of nitrite on reproductive output. Interestingly, nitrite could also protect female flies from age-dependent locomotor decline, indicating a protective effect on healthspan. NO generation from nitrite involved Drosophila commensal bacteria and was indicated by a fluorescent probe as well as direct measurements of NO gas formation with chemiluminescence.Nutrient sensing pathways such as TOR and sirtuins, have been strongly implicated in lifespan extension. In aged flies, nitrite supplementation significantly downregulated dTOR and upregulated dSir2 gene expression. Total triglycerides and glucose were decreased, a described downstream effect of both TOR and sirtuin pathways.In conclusion, we demonstrate that very low doses of dietary nitrite extend lifespan and favour healthspan in female flies. We propose modulation of nutrient sensing pathways as driving mechanisms for such effects.
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| 8. |
- Nandi, Saikat, et al.
(author)
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Generation of entanglement using a short-wavelength seeded free-electron laser
- 2024
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In: SCIENCE ADVANCES. - 2375-2548. ; 10:16
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Journal article (peer-reviewed)abstract
- Quantum entanglement between the degrees of freedom encountered in the classical world is challenging to observe due to the surrounding environment. To elucidate this issue, we investigate the entanglement generated over ultrafast timescales in a bipartite quantum system comprising two massive particles: a free-moving photoelectron, which expands to a mesoscopic length scale, and a light-dressed atomic ion, which represents a hybrid state of light and matter. Although the photoelectron spectra are measured classically, the entanglement allows us to reveal information about the dressed-state dynamics of the ion and the femtosecond extreme ultraviolet pulses delivered by a seeded free-electron laser. The observed generation of entanglement is interpreted using the time-dependent von Neumann entropy. Our results unveil the potential for using short-wavelength coherent light pulses from free-electron lasers to generate entangled photoelectron and ion systems for studying spooky action at a distance.
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| 9. |
- Nandi, Saikat, et al.
(author)
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Observation of Rabi dynamics with a short-wavelength free-electron laser
- 2022
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 608:7923
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Journal article (peer-reviewed)abstract
- Rabi oscillations are periodic modulations of populations in two-level systems interacting with a time-varying field(1). They are ubiquitous in physics with applications in different areas such as photonics(2), nano-electronics(3), electron microscopy(4) and quantum information(5). While the theory developed by Rabi was intended for fermions in gyrating magnetic fields, Autler and Townes realized that it could also be used to describe coherent light-matter interactions within the rotating-wave approximation(6). Although intense nanometre-wavelength light sources have been available for more than a decade(7-9), Rabi dynamics at such short wavelengths has not been directly observed. Here we show that femtosecond extreme-ultraviolet pulses from a seeded free-electron laser(10) can drive Rabi dynamics between the ground state and an excited state in helium atoms. The measured photoelectron signal reveals an Autler-Townes doublet and an avoided crossing, phenomena that are both fundamental to coherent atom-field interactions(11). Using an analytical model derived from perturbation theory on top of the Rabi model, we find that the ultrafast build-up of the doublet structure carries the signature of a quantum interference effect between resonant and non-resonant photoionization pathways. Given the recent availability of intense attosecond(12) and few-femtosecond(13) extreme-ultraviolet pulses, our results unfold opportunities to carry out ultrafast manipulation of coherent processes at short wavelengths using free-electron lasers.
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| 10. |
- Nandi, Saikat, et al.
(author)
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Unraveling Rabi dynamics with a seeded FEL at XUV wavelength
- 2023
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In: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023. - 9798350345995
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Conference paper (peer-reviewed)abstract
- Rabi oscillations, a prominent feature of coherent light-matter interaction arise when a two-level system interacts periodically with an external electromagnetic field [1]. Despite being a cornerstone in quantum physics, they are usually studied in the long-wavelength region, ranging from mid-infrared to visible. Here, we demonstrate that intense femtosecond extreme-ultraviolet (XUV) pulses from FERMI seeded free-electron laser [2] can drive Rabi oscillations between the two levels: 1s2 and 1s4p in helium.
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