The glycocalyx is a gel-like layer covering the luminal surface of vascular endothelial cells. It is comprised of membrane-attached proteoglycans, glycosaminoglycan chains, glycoproteins, and ...adherent plasma proteins. The glycocalyx maintains homeostasis of the vasculature, including controlling vascular permeability and microvascular tone, preventing microvascular thrombosis, and regulating leukocyte adhesion.During sepsis, the glycocalyx is degraded via inflammatory mechanisms such as metalloproteinases, heparanase, and hyaluronidase. These sheddases are activated by reactive oxygen species and pro-inflammatory cytokines such as tumor necrosis factor alpha and interleukin-1beta. Inflammation-mediated glycocalyx degradation leads to vascular hyper-permeability, unregulated vasodilation, microvessel thrombosis, and augmented leukocyte adhesion. Clinical studies have demonstrated the correlation between blood levels of glycocalyx components with organ dysfunction, severity, and mortality in sepsis.Fluid resuscitation therapy is an essential part of sepsis treatment, but overaggressive fluid therapy practices (leading to hypervolemia) may augment glycocalyx degradation. Conversely, fresh frozen plasma and albumin administration may attenuate glycocalyx degradation. The beneficial and harmful effects of fluid and plasma infusion on glycocalyx integrity in sepsis are not well understood; future studies are warranted.In this review, we first analyze the underlying mechanisms of glycocalyx degradation in sepsis. Second, we demonstrate how the blood and urine levels of glycocalyx components are associated with patient outcomes. Third, we show beneficial and harmful effects of fluid therapy on the glycocalyx status during sepsis. Finally, we address the concept of glycocalyx degradation as a therapeutic target.
We present 2603 spectra of 462 nearby Type Ia supernovae (SNe Ia), including 2065 previously unpublished spectra, obtained during 1993-2008 through the Center for Astrophysics Supernova Program. ...Based on nebular spectra of 27 SNe Ia, we find no relation between the FWHM of the iron emission feature at ~4700A and delta msub 15(B) after removing the two low-luminosity SN 1986G and SN 1991bg, suggesting that the peak luminosity is not strongly dependent on the kinetic energy of the explosion for most SNe Ia. Finally, we confirm the correlation of velocity shifts in some nebular lines with the intrinsic B-V color of SNe Ia at maximum light, although several outliers suggest a possible non-monotonic behavior for the largest blue-shifts.
Recent developments in frequency metrology and optical clocks have been based on electronic transitions in atoms and singly charged ions as references. The control over all relevant degrees of ...freedom in these atoms has enabled relative frequency uncertainties at a level of 10−18. This accomplishment not only allows for extremely accurate time and frequency measurements, but also to probe our understanding of fundamental physics, such as a possible variation of fundamental constants, a violation of the local Lorentz invariance, and the existence of forces beyond the standard model of physics. In addition, novel clocks are driving the development of sophisticated technical applications. Crucial for applications of clocks in fundamental physics are a high sensitivity to effects beyond the standard model and a small frequency uncertainty of the clock. Highly charged ions offer both. They possess optical transitions which can be extremely narrow and less sensitive to external perturbations compared to current atomic clock species. The large selection of highly charged ions offers narrow transitions that are among the most sensitive ones for the “new physics” effects. Recent experimental advances in trapping and sympathetic cooling of highly charged ions will in the future enable advanced quantum logic techniques for controlling motional and internal degrees of freedom and thus enable high-accuracy optical spectroscopy. Theoretical progress in calculating the properties of selected highly charged ions has allowed the evaluation of systematic shifts and the prediction of the sensitivity to the physics beyond the standard model. New theoretical challenges and opportunities emerge from relativistic, quantum electrodynamics, and nuclear-size contributions that become comparable with interelectronic correlations. This article reviews the current status of the field, addresses specific electronic configurations and systems which show the most promising properties for research, their potential limitations, and the techniques for their study.
Proposed quantum networks require both a quantum interface between light and matter and the coherent control of quantum states. A quantum interface can be realized by entangling the state of a single ...photon with the state of an atomic or solid-state quantum memory, as demonstrated in recent experiments with trapped ions, neutral atoms, atomic ensembles and nitrogen-vacancy spins. The entangling interaction couples an initial quantum memory state to two possible light-matter states, and the atomic level structure of the memory determines the available coupling paths. In previous work, the transition parameters of these paths determined the phase and amplitude of the final entangled state, unless the memory was initially prepared in a superposition state (a step that requires coherent control). Here we report fully tunable entanglement between a single (40)Ca(+) ion and the polarization state of a single photon within an optical resonator. Our method, based on a bichromatic, cavity-mediated Raman transition, allows us to select two coupling paths and adjust their relative phase and amplitude. The cavity setting enables intrinsically deterministic, high-fidelity generation of any two-qubit entangled state. This approach is applicable to a broad range of candidate systems and thus is a promising method for distributing information within quantum networks.
Optical atomic clocks Ludlow, Andrew D.; Boyd, Martin M.; Ye, Jun ...
Reviews of modern physics,
06/2015, Letnik:
87, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Since 1967 the primary time standard is the cesium atomic clock, based on a hyperfine transition in the microwave domain. The development of ultrastable laser sources now allows one to operate on ...electronic transitions in the optical domain, corresponding to a 5-order-of-magnitude increase in the clock frequency. This article reviews the spectacular accuracy and stability gains that can be obtained when working with laser cooled ions or neutral atoms. It also discusses some important applications of these optical clocks, from geodesy to tests of fundamental theories to many-body physics. Optical atomic clocks represent the state of the art in the frontier of modern measurement science. In this article a detailed review on the development of optical atomic clocks that are based on trapped single ions and many neutral atoms is provided. Important technical ingredients for optical clocks are discussed and measurement precision and systematic uncertainty associated with some of the best clocks to date are presented. An outlook on the exciting prospect for clock applications is given in conclusion.
Epidemiological studies indicate that traffic noise increases the incidence of coronary artery disease, hypertension and stroke. The underlying mechanisms remain largely unknown. Field studies with ...nighttime noise exposure demonstrate that aircraft noise leads to vascular dysfunction, which is markedly improved by vitamin C, suggesting a key role of oxidative stress in causing this phenomenon.
We developed a novel animal model to study the vascular consequences of aircraft noise exposure. Peak sound levels of 85 and mean sound level of 72 dBA applied by loudspeakers for 4 days caused an increase in systolic blood pressure, plasma noradrenaline and angiotensin II levels and induced endothelial dysfunction. Noise increased eNOS expression but reduced vascular NO levels because of eNOS uncoupling. Noise increased circulating levels of nitrotyrosine, interleukine-6 and vascular expression of the NADPH oxidase subunit Nox2, nitrotyrosine-positive proteins and of endothelin-1. FACS analysis demonstrated an increase in infiltrated natural killer-cells and neutrophils into the vasculature. Equal mean sound pressure levels of white noise for 4 days did not induce these changes. Comparative Illumina sequencing of transcriptomes of aortic tissues from aircraft noise-treated animals displayed significant changes of genes in part responsible for the regulation of vascular function, vascular remodelling, and cell death.
We established a novel and unique aircraft noise stress model with increased blood pressure and vascular dysfunction associated with oxidative stress. This animal model enables future studies of molecular mechanisms, mitigation strategies, and pharmacological interventions to protect from noise-induced vascular damage.
Abstract
From September 2015 until August 2017, the Advanced LIGO and Virgo gravitational-wave detectors conducted their first two observing runs O1 and O2. Since the milestone detection of ...gravitational waves from two coalescing black holes, GW150914, a further nine binary black holes collisions as well as one binary neutron star inspiral have been identified, firmly establishing the field of gravitational-wave astronomy. After a commissioning break, the third observing run commenced on April 1, 2019 which has since seen the public announcement of several tens of gravitational-wave candidate events. In this proceedings, we summarise the observations during O1 and O2 and briefly discuss the current status.
Summary
Background
The contribution of hereditary factors to the development of diverticular disease (DD) of the colon is unknown. Prevalence and location of diverticula differ in Western world ...compared to in Asia and several case reports describing families with DD have been published.
Aim
To assess the heritability of DD in a large population‐based sample of twins.
Methods
The Swedish Twin Registry was cross‐linked to the Swedish Inpatient Registry. All twins, born between 1886 and 1980 and not dead before 1969, with a discharge diagnosis of DD were identified. Twins with diagnoses of colon cancer, coeliac disease or non‐infectious colitis were excluded to decrease bias. Co‐twin odds ratio (OR), concordance rates and tetrachoric correlations were calculated for monozygotic (MZ) and same gender‐dizygotic (SS‐DZ) twins. Mx‐analyses were used to estimate the relative contributions of genetic effects and environmental factors to susceptibility for DD. Calculations were based on both primary and secondary discharge diagnoses to provide estimates reflecting impact of severity of the disease.
Results
A total of 104 452 twins met the inclusion criteria. Of these, 2296 had a diagnosis of DD. The OR of developing the disease given one's co‐twin was affected was 7.15 (95% CI: 4.82–10.61) for MZ and 3.20 (95% CI: 2.21–4.63) for SS‐DZ twins. Similarly, concordance rates and tetrachoric correlations were higher in MZ than those in SS‐DZ twins. The heritability was estimated to 40% and the non shared environmental effects to 60%.
Conclusion
Genetic susceptibility is an important component, along with individual specific environmental factors, for the development of diverticular disease of the colon.
Finding alternative optoelectronic mechanisms that overcome the limitations of conventional semiconductor devices is paramount for detecting and harvesting low-energy photons. A highly promising ...approach is to drive a current from the thermal energy added to the free-electron bath as a result of light absorption. Successful implementation of this strategy requires a broadband absorber where carriers interact among themselves more strongly than with phonons, as well as energy-selective contacts to extract the excess electronic heat. Here we show that graphene-WSe2-graphene heterostructure devices offer this possibility through the photo-thermionic effect: the absorbed photon energy in graphene is efficiently transferred to the electron bath leading to a thermalized hot carrier distribution. Carriers with energy higher than the Schottky barrier between graphene and WSe2 can be emitted over the barrier, thus creating photocurrent. We experimentally demonstrate that the photo-thermionic effect enables detection of sub-bandgap photons, while being size-scalable, electrically tunable, broadband and ultrafast.
Coronavirus disease 2019 (COVID-19), the clinical syndrome associated with infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has impacted nearly every country in the world. ...Despite an unprecedented focus of scientific investigation, there is a paucity of evidence-based pharmacotherapies against this disease. Because of this lack of data-driven treatment strategies, broad variations in practice patterns have emerged. Observed hypercoagulability in patients with COVID-19 has created debate within the critical care community on the therapeutic utility of heparin. We seek to provide an overview of the data supporting the therapeutic use of heparin, both unfractionated and low molecular weight, as an anticoagulant for the treatment of SARS-CoV-2 infection. Additionally, we review preclinical evidence establishing biological plausibility for heparin and synthetic heparin-like drugs as therapies for COVID-19 through antiviral and anti-inflammatory effects. Finally, we discuss known adverse effects and theoretical off-target effects that may temper enthusiasm for the adoption of heparin as a therapy in COVID-19 without confirmatory prospective randomized controlled trials. Despite previous failures of anticoagulants in critical illness, plausibility of heparin for COVID-19 is sufficiently robust to justify urgent randomized controlled trials to determine the safety and effectiveness of this therapy.
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