1,021 research outputs found
Ab initio calculations of spectroscopic constants and vibrational state lifetimes of diatomic alkali-alkaline-earth cations
We investigate the lifetimes of vibrational states of diatomic alkali-alkaline-earth cations to determine their suitability for ultracold experiments where long decoherence time and controllability by an external electric field are desirable. The potential energy and permanent dipole moment curves for the ground electronic states of LiBe+, LiMg+, NaBe+, and NaMg+ are obtained using the coupled cluster with singles doubles and triples and multireference configuration interaction methods in combination with large all-electron cc-pCVQZ and aug-cc-pCV5Z basis sets. The energies and wave functions of all vibrational states are obtained by solving the Schrodinger equation for nuclei with the B-spline basis set method. To predict the lifetimes of vibrational states, the transition dipole moments, as well as the Einstein coefficients describing spontaneous emission, and the stimulated absorption and emission induced by black body radiation are calculated. Surprisingly, in all studied ions, the lifetimes of the highest excited vibrational states are similar to the lifetimes of the ground vibrational states indicating that highly vibrationally excited ions could be useful for the ultracold experiments requiring long decoherence time. Published by AIP Publishing.
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Fedorov, D. A., Barnes, D. K., & Varganov, S. A. (2017). Ab initio calculations of spectroscopic constants and vibrational state lifetimes of diatomic alkali-alkaline-earth cations. The Journal of chemical physics, 147(12), 124304. and may be found at https://doi.org/10.1063/1.4986818
A potential role for mTORC1/2 in β2 adrenergic regulation of skeletal muscle glucose oxidation in models of intrauterine growth restriction.
The epidemic of intrauterine growth restriction (IUGR) continues to be a leading cause of perinatal morbidity and mortality throughout the world. This condition has been linked to the development of metabolic health problems such as obesity, hypertension, glucose intolerance, and type 2 diabetes at all ages. Previous studies have demonstrated that IUGR fetal adaptations impair proper glucose homeostasis in part via changes in insulin responsiveness in key tissues including skeletal muscle and liver, and that these deficits persists into adulthood. Many components of insulin signaling pathways associated with glucose metabolic regulation have been evaluated in IUGR tissues for adaptive changes. Among these are mammalian target of rapamycin complexes 1 and 2 (mTORC1/2) and their associated pathways, which function in mitochondrial control and maintenance. However, recent findings demonstrate that β2 adrenoceptors (β2AR) appear to activate an insulin-independent pathway or pathways that modify glucose metabolism via mTORC1/2 complexes. These findings represent a novel potential target for interventions that could improve the treatment and prevention of IUGR-induced metabolic disorders. This review will focus on mechanistic components of β2AR-mTORC1/2 signaling as well as their role in regulating glucose oxidative metabolism within skeletal muscle
Impaired muscle stem cell function in cows with high concentrations of androstenedione in their follicular fluid
It is unclear whether androstenedione (A4) increases muscle mass and strength similar to testosterone or whether it produces primarily catabolic effects on muscle-like estrogen (Rasmussen et al., 2000). Summers et al. (2014) observed two populations of cows that exhibit either high (\u3e40 ng/mL; High A4) or low (\u3c20 ng/mL; Low A4) concentrations of A4 within the fluid of the dominant follicle just prior to ovulation. High A4 cows had decreased reproductive rates and shorter times before falling out of the herd, but those that did produce calves weaned them ~10-kg heavier than their low A4 counterparts (Summers et al., 2014). It appears that the difference in weights is due to faster growing and more efficient skeletal muscle. High A4 cows share many characteristics with women suffering from polycystic ovary syndrome (PCOS), whose high levels of circulating androgens are associated with changes in body composition (Kirchengast and Huber, 2001)
ASAS-SSR Triennnial Reproduction Symposium: Looking Back and Moving Forward—How Reproductive Physiology has Evolved: Fetal origins of impaired muscle growth and metabolic dysfunction: Lessons from the heat-stressed pregnant ewe
Intrauterine growth restriction (IUGR) is the second leading cause of perinatal mortality and predisposes offspring to metabolic disorders at all stages of life. Muscle-centric fetal adaptations reduce growth and yield metabolic parsimony, beneficial for IUGR fetal survival but detrimental to metabolic health after birth. Epidemiological studies have reported that IUGRborn children experience greater prevalence of insulin resistance and obesity, which progresses to diabetes, hypertension, and other metabolic disorders in adulthood that reduce quality of life. Similar adaptive programming in livestock results in decreased birth weights, reduced and inefficient growth, decreased carcass merit, and substantially greater mortality rates prior to maturation. High rates of glucose consumption and metabolic plasticity make skeletal muscle a primary target for nutrient-sparing adaptations in the IUGR fetus, but at the cost of its contribution to proper glucose homeostasis after birth. Identifying the mechanisms underlying IUGR pathophysiology is a fundamental step in developing treatments and interventions to improve outcomes in IUGR-born humans and livestock. In this review, we outline the current knowledge regarding the adaptive restriction of muscle growth and alteration of glucose metabolism that develops in response to progressively exacerbating intrauterine conditions. In addition, we discuss the evidence implicating developmental changes in β adrenergic and inflammatory systems as key mechanisms for dysregulation of these processes. Lastly, we highlight the utility and importance of sheep models in developing this knowledge
Sustained maternal inflammation during the early third trimester yields fetal adaptations that impair subsequent skeletal muscle growth and glucose metabolism in sheep
Intrauterine growth restriction (IUGR) is linked to metabolic dysfunction in offspring, but the mediating mechanisms are still under investigation (Barker et al., 1993). IUGR fetuses adapt to their poor intrauterine environment by repartitioning nutrients to organs critical for survival (i.e., brain, heart) at the expense of tissues such as muscle (Yates et al., 2012c). These developmental adaptations help the fetus to survive in utero but have lifelong consequences in offspring; persistent reduction of highly metabolic muscle mass is detrimental to glucose homeostasis (DeFronzo et al., 1981). Glucose metabolism is regulated primarily by insulin, and nutrient depravation is associated with impaired β-cell mass, insulin secretion, and insulin action in the IUGR fetus (Limesand et al., 2006). Moreover, inflammation disrupts insulin action and aids in the development of insulin resistance (Bach et al., 2013). We recently showed that inflammatory cytokines acutely stimulate glucose metabolism despite their antagonistic effects on insulin signaling (Cadaret et al., 2017b). However, we hypothesize that chronic exposure alters responsiveness to cytokines and results in basal cytokine concentrations having a greater inhibitory tone. Furthermore, chronic maternal inflammation may induce fetal inflammatory adaptations that impair muscle growth and metabolism. Therefore, our objective was to determine the effects of sustained maternal inflammation on fetal growth, islet function, and muscle glucose metabolism
Sustained maternal inflammation during the early third trimester yields fetal adaptations that impair subsequent skeletal muscle growth and glucose metabolism in sheep
Intrauterine growth restriction (IUGR) is linked to metabolic dysfunction in offspring, but the mediating mechanisms are still under investigation (Barker et al., 1993). IUGR fetuses adapt to their poor intrauterine environment by repartitioning nutrients to organs critical for survival (i.e., brain, heart) at the expense of tissues such as muscle (Yates et al., 2012c). These developmental adaptations help the fetus to survive in utero but have lifelong consequences in offspring; persistent reduction of highly metabolic muscle mass is detrimental to glucose homeostasis (DeFronzo et al., 1981). Glucose metabolism is regulated primarily by insulin, and nutrient depravation is associated with impaired β-cell mass, insulin secretion, and insulin action in the IUGR fetus (Limesand et al., 2006). Moreover, inflammation disrupts insulin action and aids in the development of insulin resistance (Bach et al., 2013). We recently showed that inflammatory cytokines acutely stimulate glucose metabolism despite their antagonistic effects on insulin signaling (Cadaret et al., 2017b). However, we hypothesize that chronic exposure alters responsiveness to cytokines and results in basal cytokine concentrations having a greater inhibitory tone. Furthermore, chronic maternal inflammation may induce fetal inflammatory adaptations that impair muscle growth and metabolism. Therefore, our objective was to determine the effects of sustained maternal inflammation on fetal growth, islet function, and muscle glucose metabolism
Using line acceleration to measure false killer whale (Pseudorca crassidens) click and whistle source levels during pelagic longline depredation
False killer whales (Pseudorca crassidens) depredate pelagic longlines in offshore Hawaiian waters. On January 28, 2015 a depredation event was recorded 14m from an integrated GoPro camera, hydrophone, and accelerometer, revealing that false killer whales depredate bait and generate clicks and whistles under good visibility conditions. The act of plucking bait off a hook generated a distinctive 15 Hz line vibration. Two similar line vibrations detected at earlier times permitted the animal’s range and thus signal source levels to be estimated over a 25-min window. Peak power spectral density source levels for whistles (4–8 kHz) were estimated to be between 115 and 130 dB re 1 lPa2/Hz @ 1 m. Echolocation click source levels over 17–32 kHz bandwidth reached 205 dB re 1lPa @ 1 m pk-pk, or 190 dB re 1lPa @ 1 m (root-meansquare). Predicted detection ranges of the most intense whistles are 10 to 25 km at respective sea states of 4 and 1, with click detection ranges being 5 times smaller than whistles. These detection range analyses provide insight into how passive acoustic monitoring might be used to both quantify and avoid depredation encounters.The authors are indebted to Captain Jerry Ray and the rest of the F/V Katy Mary crew for permitting the camera gear to be deployed during their longline fishing trip. Robert Glatts designed the custom GoPro circuit board, and Will Cerf assisted with video footage analysis. This research was sponsored by Derek Orner under the Bycatch Reduction Engineering Program (BREP) at the National Oceanic and Atmospheric Administration (NOAA).Ye
Governing and accelerating transformative entrepreneurship: exploring the potential for small business innovation on urban sustainability transitions
The alluring yet nebulous concept of transformative change is increasingly gaining traction in conversations about pathways to more sustainable futures. As such, new conceptual tools are needed to illuminate variety of actors, interests, and capacities at play in potentially radical experiments. This paper draws upon multi-level governance theory, sustainability transitions scholarship, and sustainability entrepreneurship literature, to interrogate the transformative potential of small and medium-sized enterprises (SMEs). We (1) identify characteristics of SMEs that might make them relatively more able to produce radical innovations, (2) explore dimensions of the broader socio-political context that influence the likelihood of this potential to be translated into action in urban spaces, and (3) discuss implications of these dynamics for transformative sustainability governance
Governing and accelerating transformative entrepreneurship: exploring the potential for small business innovation on urban sustainability transitions
The alluring yet nebulous concept of transformative change is increasingly gaining traction in conversations about pathways to more sustainable futures. As such, new conceptual tools are needed to illuminate variety of actors, interests, and capacities at play in potentially radical experiments. This paper draws upon multi-level governance theory, sustainability transitions scholarship, and sustainability entrepreneurship literature, to interrogate the transformative potential of small and medium-sized enterprises (SMEs). We (1) identify characteristics of SMEs that might make them relatively more able to produce radical innovations, (2) explore dimensions of the broader socio-political context that influence the likelihood of this potential to be translated into action in urban spaces, and (3) discuss implications of these dynamics for transformative sustainability governance
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