Littérature scientifique sur le sujet « Reversed heme »
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Articles de revues sur le sujet "Reversed heme"
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Reidl, J., et J. J. Mekalanos. « Lipoprotein e(P4) is essential for hemin uptake by Haemophilus influenzae. » Journal of Experimental Medicine 183, no 2 (1 février 1996) : 621–29. http://dx.doi.org/10.1084/jem.183.2.621.
Texte intégralRésumé :
Heme uptake is a common means of iron and porphyrin acquisition by many pathogenic bacteria. The genus Haemophilus includes several important pathogenic bacterial species that characteristically require hemin-, protoporphyrin-, or heme-substituted proteins as essential growth factors under aerobic conditions. However, the mechanism of heme transport is not understood for Haemophilus. We have cloned a DNA fragment from H. influenzae that allows an Escherichia coli hemA mutant to employ exogenous hemin or protoporphyrin IX as sole sources of porphyrin. DNA sequencing of the cloned DNA fragment suggested that a previously characterized gene (hel) encoding an antigenic, outer membrane lipoprotein e(P4) was responsible for the complementation activity. Construction of hel insertion mutations in strain H. influenzae Rd demonstrated that hel is essential for growth under aerobic conditions but not under anaerobic conditions. The aerobic growth defect of hel mutants could be reversed by providing exogenous hemin in the presence of outer membrane. The analysis of hybrids between e(P4) and beta-lactamase demonstrated that a domain of e(P4) near its NH2' terminus was required for its function in hemin use. Within this domain is a short amino acid sequence that displays similarity to H. influenzae hemin binding protein HbpA, hemin-binding motifs present in eukaryotic transcription activator heme-activated protein, and the heme containing proteins hemoglobin (alpha-chain) and cytochrome C3, suggesting that this region may be involved in hemin binding and/or transport.
2
Qian, XiaoWei, Hao Cheng et XinZhong Chen. « Transient receptor potential melastatin 2–mediated heme oxygenase-1 has a role for bacterial clearance by regulating autophagy in peritoneal macrophages during polymicrobial sepsis ». Innate Immunity 25, no 8 (19 septembre 2019) : 530–38. http://dx.doi.org/10.1177/1753425919875796.
Texte intégralRésumé :
Our previous study indicated an important protective role of transient receptor potential melastatin 2 (TRPM2) in controlling bacterial clearance in macrophages during polymicrobial sepsis by regulating heme oxygenase-1. Autophagy is necessary for macrophages to kill invasive bacteria. In the present study, TRPM2 knockout (KO) mice show decreased heme oxygenase-1 and autophagy in peritoneal macrophages after caecal ligation and puncture surgery. Caecal ligation and puncture-induced autophagy in peritoneal macrophages is dependent on heme oxygenase-1. TRPM2 KO mice treated with heme oxygenase-1 inducer before caecal ligation and puncture significantly increase autophagy of peritoneal macrophages, bacterial clearance rate and survival rate. In addition, TRPM2 KO mice treated with heme oxygenase-1 inducer before caecal ligation and puncture significantly attenuate organ injury and systemic inflammation. These improvements are reversed by autophagy inhibitor. Therefore, our findings suggest that TRPM2-mediated heme oxygenase-1 has a role for bacterial clearance possibly by regulating autophagy in peritoneal macrophages during polymicrobial sepsis.
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Steiner, Alexandre A., Eduardo Colombari et Luiz G. S. Branco. « Carbon monoxide as a novel mediator of the febrile response in the central nervous system ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 277, no 2 (1 août 1999) : R499—R507. http://dx.doi.org/10.1152/ajpregu.1999.277.2.r499.
Texte intégralRésumé :
Heme oxygenase catalyzes the metabolism of heme to biliverdin, free iron, and carbon monoxide (CO), which has been shown to be an important neuromodulatory agent. Recently, it has been demonstrated that lipopolysaccharide (LPS) can induce the enzyme heme oxygenase in glial cells. Therefore, the present study was designed to test the hypothesis that central CO plays a role in LPS-induced fever. Colonic body temperature (Tb) was measured in awake, unrestrained rats (basal Tb= 36.8 ± 0.2°C). Intracerebroventricular injection of zinc deuteroporphyrin 2,4-bis glycol (ZnDPBG; 75 nmol), a heme oxygenase inhibitor, caused no significant change in Tb, indicating that the central heme oxygenase pathway plays no tonic role in Tb under the experimental conditions used. Intraperitoneal injections of LPS (50–100 μg/kg) evoked dose-dependent increases in Tb. Intracerebroventricular injection of ZnDPBG in febrile rats attenuated LPS-induced fever (thermal index with ZnDPBG = 1.1 ± 0.2°C, thermal index with vehicle = 2.3 ± 0.4°C), suggesting that the central heme oxygenase pathway plays a role in fever generation. The antipyretic effect of ZnDPBG could be reversed by intracerebroventricular administration of heme-lysinate or CO-saturated saline. Collectively, our data indicate that CO arising from heme oxygenase may play an important role in fever generation by acting on the central nervous system.
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Liu, Yunfeng, Fangmiao Jing, Woelsung Yi, Avital Mendelson, Patricia Shi, Ronald Walsh, David F. Friedman et al. « HO-1hi patrolling monocytes protect against vaso-occlusion in sickle cell disease ». Blood 131, no 14 (5 avril 2018) : 1600–1610. http://dx.doi.org/10.1182/blood-2017-12-819870.
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Key Points SCD patients with a recent VOC episode have lower frequencies and numbers of HO-1hi patrolling monocytes. Heme-driven SCD vaso-occlusion is exacerbated in mice lacking patrolling monocytes and reversed following patrolling monocyte transfer.
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Mikhael, Marc, Sameer Apte, Shan Soe-Lin et Prem Ponka. « Nitrogen Monoxide Inhibits Heme Synthesis In Reticulocytes ». Blood 116, no 21 (19 novembre 2010) : 4252. http://dx.doi.org/10.1182/blood.v116.21.4252.4252.
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Abstract Abstract 4252 Anemia of chronic disease (ACD) is a condition that often manifests in patients with chronic immune activation due to chronic infections, autoimmune disorders, cancer and other diseases. The pathogenesis of ACD is complex and involves inefficient erythropoietin production, immune-mediated inhibition of erythropoiesis, and retention of iron in hemoglobin-processing macrophages. During their development, erythroid cells are closely associated with macrophages. In inflammatory conditions, activated macrophages generate large quantities of the gaseous molecule, nitric oxide (NO), which has numerous effects on iron metabolism. In this study, we explored the possibility that NO affects iron metabolism in erythroid cells. We treated reticulocytes with the NO donors, sodium nitroprusside (SNP) and S-Nitroso-N-acetyl-D,L-penicillamine (SNAP). We show that NO inhibits 59Fe incorporation from 59Fe-transferrin into reticulocytes and their heme. Significantly, 5-aminolevulinic acid (ALA, the product of ALA synthase, which catalyzes the first step of heme synthesis) reversed the SNP-mediated decrease in 59Fe incorporation into heme but not the cellular 59Fe uptake. In addition, SNP treatment led to an increase in eIF2α phosphorylation (which is known to occur in heme-deficient cells) and decreased globin translation. Importantly, the addition of ALA to SNP-treated reticulocytes prevented the effect of SNP on eIF2α phosphorylation and reversed globin synthesis inhibition. This indicates that in SNP treated reticulocytes, the phosphorylation of eIF2α and inhibition of globin synthesis occur indirectly, via NO's effect on erythroid-specific ALA synthase (ALA-S2). These results led us to conclude that NO has two distinct effects on reticulocytes, namely: a decrease in ALA-S2 activity and a decrease in transferrin-mediated iron uptake. The profound impact of NO on heme synthesis, iron uptake and globin translation in reticulocytes raises the possibility that NO production by macrophages could also contribute to ACD. Disclosures: No relevant conflicts of interest to declare.
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Hodge, M. R., G. Kim, K. Singh et M. G. Cumsky. « Inverse regulation of the yeast COX5 genes by oxygen and heme ». Molecular and Cellular Biology 9, no 5 (mai 1989) : 1958–64. http://dx.doi.org/10.1128/mcb.9.5.1958-1964.1989.
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The COX5a and COX5b genes encode divergent forms of yeast cytochrome c oxidase subunit V. Although the polypeptide products of the two genes are functionally interchangeable, it is the Va subunit that is normally found in preparations of yeast mitochondria and cytochrome c oxidase. We show here that the predominance of subunit Va stems in part from the differential response of the two genes to the presence of molecular oxygen. Our results indicate that during aerobic growth, COX5a levels were high, while COX5b levels were low. Anaerobically, the pattern was reversed; COX5a levels dropped sevenfold, while those of COX5b were elevated sevenfold. Oxygen appeared to act at the level of transcription through heme, since the addition of heme restored an aerobic pattern of transcription to anaerobically grown cells and the effect of anaerobiosis on COX5 transcription was reproduced in strains containing a mutation in the heme-biosynthetic pathway (hem1). In conjunction with the oxygen-heme response, we determined that the product of the ROX1 gene, a trans-acting regulator of several yeast genes controlled by oxygen, is also involved in COX5 expression. These results, as well as our observation that COX5b expression varied significantly in certain yeast strains, indicate that the COX5 genes undergo a complex pattern of regulation. This regulation, especially the increase in COX5b levels anaerobically, may reflect an attempt to modulate the activity of a key respiratory enzyme in response to varying environmental conditions. The results presented here, as well as those from other laboratories, suggest that the induction or derepression of certain metabolic enzymes during anaerobiosis may be a common and important physiological response in yeast cells.
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Hodge, M. R., G. Kim, K. Singh et M. G. Cumsky. « Inverse regulation of the yeast COX5 genes by oxygen and heme. » Molecular and Cellular Biology 9, no 5 (mai 1989) : 1958–64. http://dx.doi.org/10.1128/mcb.9.5.1958.
Texte intégralRésumé :
The COX5a and COX5b genes encode divergent forms of yeast cytochrome c oxidase subunit V. Although the polypeptide products of the two genes are functionally interchangeable, it is the Va subunit that is normally found in preparations of yeast mitochondria and cytochrome c oxidase. We show here that the predominance of subunit Va stems in part from the differential response of the two genes to the presence of molecular oxygen. Our results indicate that during aerobic growth, COX5a levels were high, while COX5b levels were low. Anaerobically, the pattern was reversed; COX5a levels dropped sevenfold, while those of COX5b were elevated sevenfold. Oxygen appeared to act at the level of transcription through heme, since the addition of heme restored an aerobic pattern of transcription to anaerobically grown cells and the effect of anaerobiosis on COX5 transcription was reproduced in strains containing a mutation in the heme-biosynthetic pathway (hem1). In conjunction with the oxygen-heme response, we determined that the product of the ROX1 gene, a trans-acting regulator of several yeast genes controlled by oxygen, is also involved in COX5 expression. These results, as well as our observation that COX5b expression varied significantly in certain yeast strains, indicate that the COX5 genes undergo a complex pattern of regulation. This regulation, especially the increase in COX5b levels anaerobically, may reflect an attempt to modulate the activity of a key respiratory enzyme in response to varying environmental conditions. The results presented here, as well as those from other laboratories, suggest that the induction or derepression of certain metabolic enzymes during anaerobiosis may be a common and important physiological response in yeast cells.
8
Alvarado, Gerardo, Attila Tóth, Éva Csősz, Gergő Kalló, Katalin Dankó, Zoltán Csernátony, Ann Smith et al. « Heme-Induced Oxidation of Cysteine Groups of Myofilament Proteins Leads to Contractile Dysfunction of Permeabilized Human Skeletal Muscle Fibres ». International Journal of Molecular Sciences 21, no 21 (31 octobre 2020) : 8172. http://dx.doi.org/10.3390/ijms21218172.
Texte intégralRésumé :
Heme released from red blood cells targets a number of cell components including the cytoskeleton. The purpose of the present study was to determine the impact of free heme (20–300 µM) on human skeletal muscle fibres made available during orthopedic surgery. Isometric force production and oxidative protein modifications were monitored in permeabilized skeletal muscle fibre segments. A single heme exposure (20 µM) to muscle fibres decreased Ca2+-activated maximal (active) force (Fo) by about 50% and evoked an approximately 3-fold increase in Ca2+-independent (passive) force (Fpassive). Oxidation of sulfhydryl (SH) groups was detected in structural proteins (e.g., nebulin, α-actinin, meromyosin 2) and in contractile proteins (e.g., myosin heavy chain and myosin-binding protein C) as well as in titin in the presence of 300 µM heme. This SH oxidation was not reversed by dithiothreitol (50 mM). Sulfenic acid (SOH) formation was also detected in the structural proteins (nebulin, α-actinin, meromyosin). Heme effects on SH oxidation and SOH formation were prevented by hemopexin (Hpx) and α1-microglobulin (A1M). These data suggest that free heme has a significant impact on human skeletal muscle fibres, whereby oxidative alterations in structural and contractile proteins limit contractile function. This may explain and or contribute to the weakness and increase of skeletal muscle stiffness in chronic heart failure, rhabdomyolysis, and other hemolytic diseases. Therefore, therapeutic use of Hpx and A1M supplementation might be effective in preventing heme-induced skeletal muscle alterations.
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Ahmad, Mansoor, Xiangmin Zhao, Melissa R. Kelly, Sharath Kandhi, Oscar Perez, Nader G. Abraham et Michael S. Wolin. « Heme oxygenase-1 induction modulates hypoxic pulmonary vasoconstriction through upregulation of ecSOD ». American Journal of Physiology-Heart and Circulatory Physiology 297, no 4 (octobre 2009) : H1453—H1461. http://dx.doi.org/10.1152/ajpheart.00315.2009.
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Endothelium-denuded bovine pulmonary arteries (BPA) contract to hypoxia through a mechanism potentially involving removing a superoxide-derived hydrogen peroxide-mediated relaxation. BPA organ cultured for 24 h with 0.1 mM cobalt chloride (CoCl2) to increase the expression and activity of heme oxygenase-1 (HO-1) is accompanied by a decrease in 5 μM lucigenin-detectable superoxide and an increase in horseradish peroxidase-luminol detectable peroxide levels. Force development to KCl in BPA was not affected by increases in HO-1, but the hypoxic pulmonary vasoconstriction (HPV) response was decreased. Organ culture with a HO-1 inhibitor (10 μM chromium mesoporphyrin) reversed the effects of HO-1 on HPV and peroxide. Treatment of HO-1-induced BPA with extracellular catalase resulted in reversal of the attenuation of HPV without affecting the force development to KCl. Increasing intracellular peroxide scavenging with 0.1 mM ebselen increased force development to KCl and partially reversed the decrease in HPV seen on induction of HO-1. HO-1 induction increases extracellular (ec) superoxide dismutase (SOD) expression without changing Cu,Zn-SOD and Mn-SOD levels. HO-1-induced BPA rings treated with the copper chelator 10 mM diethyldithiocarbamate to inactivate ecSOD and Cu,Zn-SOD showed increased superoxide and decreased peroxide to levels equal to non-HO-1-induced rings, whereas the addition of SOD to freshly isolated BPA rings attenuated HPV similar to HO-1 induction with CoCl2. Therefore, HO-1 induction in BPA increases ecSOD expression associated with enhanced generation of peroxide in amounts that may not be adequately removed during hypoxia, leading to an attenuation of HPV.
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Iwadate, Reiko, Yoko Satoh, Yukino Watanabe, Hiroshi Kawai, Naomi Kudo, Yoichi Kawashima, Tadahiko Mashino et Atsushi Mitsumoto. « Impairment of heme biosynthesis induces short circadian period in body temperature rhythms in mice ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 303, no 1 (1 juillet 2012) : R8—R18. http://dx.doi.org/10.1152/ajpregu.00019.2011.
Texte intégralRésumé :
It has been demonstrated that the function of mammalian clock gene transcripts is controlled by the binding of heme in vitro. To examine the effects of heme on biological rhythms in vivo, we measured locomotor activity (LA) and core body temperature (Tb) in a mouse model of porphyria with impaired heme biosynthesis by feeding mice a griseofulvin (GF)-containing diet. Mice fed with a 2.0% GF-containing diet (GF2.0) transiently exhibited phase advance or phase advance-like phenomenon by 1–3 h in terms of the biological rhythms of Tbor LA, respectively (both, P < 0.05) while mice were kept under conditions of a light/dark cycle (12 h:12 h). We also observed a transient, ∼0.3 h shortening of the period of circadian Tbrhythms in mice kept under conditions of constant darkness ( P < 0.01). Interestingly, the observed duration of abnormal circadian rhythms in GF2.0 mice lasted between 1 and 3 wk after the onset of GF ingestion; this finding correlated well with the extent of impairment of heme biosynthesis. When we examined the effects of therapeutic agents for acute porphyria, heme, and hypertonic glucose on the pathological status of GF2.0 mice, it was found that the intraperitoneal administration of heme (10 mg·kg−1·day−1) or glucose (9 g·kg−1·day−1) for 7 days partially reversed (50%) increases in urinary δ-aminolevulinic acids levels associated with acute porphyria. Treatment with heme, but not with glucose, suppressed the phase advance (-like phenomenon) in the diurnal rhythms ( P < 0.05) and restored the decrease of heme ( P < 0.01) in GF2.0 mice. These results suggest that impairments of heme biosynthesis, in particular a decrease in heme, may affect phase and period of circadian rhythms in animals.
Thèses sur le sujet "Reversed heme"
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Silva, Ingrid de Oliveira e. « Inibição e reversão da maturação nuclear, avaliação da maturação citoplasmática e produção de esteróides em complexos cumulus oophorus bovinos co-cultivados com hemi-secções foliculares em meio de cultura definido ». reponame:Repositório Institucional da UnB, 2008. http://repositorio.unb.br/handle/10482/1120.
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Dissertação (mestrado)—Universidade de Brasília, Faculdade de Medicina, 2008.Submitted by Jaqueline Oliveira (jaqueoliveiram@gmail.com) on 2008-12-03T17:25:03Z No. of bitstreams: 1 DISSERTACAO_2008_IngridOliveiraSilva.pdf: 1065354 bytes, checksum: 5c704b05ad9fbdc93257f3bf700ca39a (MD5)
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O presente trabalho teve o objetivo de padronizar um protocolo de pré-maturação, onde complexos cumulus oophorus (COCs- do inglês cumulus oocyte complex) bovinos imaturos são co-cultivados com hemi-secções foliculares (HS) em meio definido (α-MEM+PVA). No experimento 1 foi avaliado, o efeito deste co-cultivo pelo período de 24 horas na manutenção do estágio imaturo dos COCs. Os grupos experimentais avaliados foram: G1=TCM- 199+SFB+COCs; G2=TCM-199+SFB+HS+COCs; G3=α-MEM+PVA+COCs; G4=α- MEM+PVA+HS+COCs. No experimento 2, foi feita a avaliação do potencial de reversibilidade do processo inibitório após a pré-maturação, cultivando os COCs previamente pré-maturados em meio de maturação padrão (TCM-199+SFB). Os meios de cultivo destes experimentos foram armazenados a –20° C para posterior dosagem dos hormônios estradiol (E2) e progesterona (P4) com a utilização de kits de radioimunoensaio. Em média 4 COCs de cada tratamento dos experimentos 1 e 2 foram processados para análise da maturação citoplasmática ao microscópio eletrônico de transmissão. Os resultados do experimento 1 mostram que, os tratamentos G2, G3 e G4 foram efetivos na inibição da progressão da meiose, com respectivamente 81,2; 74,0 e 96,3% dos COCs imaturos. O tratamento G1 (controle) apresentou ao final do tempo de cultivo 83,1% de COCs maduros; P<0,05. No experimento 2, somente os grupos G1 e G3 apresentaram mais de 80% de oócitos maduros ao final das 24 horas de cultura em meio padrão. Os grupos G2 e G4 apresentaram apenas 29,1 e 16,3% respectivamente dos COCs maduros ao final do cultivo; P<0,05. A dosagem dos hormônios esteróides mostrou no experimento 1, que o grupo G3 apresentou a maior produção de E2 (2444,24 pg/mL) e menor produção de P4 (3,47 ng/mL); P<0,0001. A produção de P4 foi máxima no grupo G2 (77,87 ng/mL). A presença das HS promoveu o aumento da produção deste hormônio nos grupos G2 e G4. No experimento 2, a concentração de E2 foi maior no grupo pré-maturado em meio definido, assim como a concentração de P4, que foi significativamente maior neste tratamento (G3), 42,82 ng/mL; P< 0,0032. A análise ultraestrutural dos COCs mostrou que a presença das HS (grupos G2 e G4) provoca a morte destes ainda no período de pré-maturação. No grupo G3, foi observado que o meio de cultivo α-MEM+PVA promoveu o início da maturação citoplasmática durante a pré-maturação. No experimento 2, este processo foi completado após o cultivo em meio de maturação padrão. Conclui-se portanto que o meio de cultura α-MEM+PVA fornece um ambiente adequado para que os COCs sofram a pré-maturação, já que a relação E2:P4 neste sistema é condizente com a fase em que os COCs se encontram, além de que este meio propicia uma alta taxa de inibição da maturação nuclear seguida de uma grande porcentagem de reversão desta inibição. Outro fato importante foi que a maturação citoplasmática foi iniciada ainda no período de prématuração, e chegou a termo durante a maturação in vitro. O co-cultivo com HS, no entanto, não gerou resultados promissores. ___________________________________________________________________________________ ABSTRACT
This study aimed to standardize a physiological protocol of pre- maturation, where immature bovine cumulus oocyte complex (COCs) are co-cultured with follicular hemissections (HS) in defined medium (α-MEM + PVA). In the first experiment it was evaluated, the effect of this co-culture for the period of 24 hours in the maintenance of COCs’ immature stage. The following experimental groups evaluated were: G1=TCM-199 +FCS+COCs; G2=TCM- 199+FCS+HS+COCs; G3=α-MEM+PVA+COCs; G4=α-MEM+PVA+HS+COCs. The experiment 2 was performed to assess the reversibility potential of the inhibitory process after the pre-maturation. COCs previously pre-matured were cultured in standard medium of maturation (TCM-199 + SFB). The culture medium of these experiments were stored at -20° C for later dosage of hormones estradiol (E2) and progesterone (P4) with radioimmunoassay kits. On average 4 COCs of each treatment of experiments 1 and 2 were processed for cytoplasmic maturation analysis at the transmission electron microscope. The results of the experiment 1 show that the treatments G2, G3 and G4 were effective in maintain meiotic arrest, with 81.2, 74.0 and 96.3% respectively of immature COCs. Treatment G1 (control) showed at the end of culture 83.1% of mature COCs, P <0.05. In experiment 2, only the groups G1 and G3 showed more than 80% of mature oocytes at the end of 24 hours of culture in the medium standard. The groups G2 and G4 had only 29.1 and 16.3% respectively of the mature COCs at the end of the culture, P<0.05. The dosage of steroid hormones in Experiment 1 showed that the G3 had the highest production of E2 (2444.24 pg / mL) and lower production of P4 (3.47 ng / mL), P <0.0001. The production of P4 was the highest in group G2 (77.87 ng / mL). Due the presence of HS there was an increasing production of this hormone in groups G2 and G4. In experiment 2, the concentration of E2 was higher in group pre-matured in defined medium, as well as the concentration of P4, which was significantly higher in this treatment, 42.82 ng / mL, P<0.0032.The ultrastructural analysis of the COCs showed that the presence of HS (groups G2 and G4) causes the cellular death still in the prematuration culture. In group G3, it was observed that the medium α-MEM + PVA promoted the beginning of the cytoplasmic maturation during the pre-maturation. In experiment 2, this process has been completed after culture in standard maturation medium. It comes to the conclusion that the culture α-MEM + PVA provides a suitable environment for the COCs suffer a pre-maturation, as the relationship E2: P4 in this system is consistent with the stage in which the COCs are. In addition, this system provides a high rate of inhibition of nuclear maturation followed by a large percentage of reversal of this inhibition. Another important fact is that the cytoplasmic maturation began still in the prematuration period, and finished during in vitro maturation. The co-culture with HS, didn’t generate promising results.
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Ronchi, Nicolò. « An investigation of defects and reliability issues on Gallium Nitride devices ». Doctoral thesis, Università degli studi di Padova, 2012. http://hdl.handle.net/11577/3421973.
Texte intégralRésumé :
In this thesis a extensive study of devices based on AlGaN/GaN heterostructure is reported. The work is fundamentally divided in two main topic: the first part is related to the investigation of traps and defects and their effects on the device performances; the second part is instead related to the reliability studies of this type of devices.
The investigation of trapping effects is based on pulsed measurements of output characteristic and transcharacteristic of the device under test. The measurements carried out on High Electron Mobility Transistors (HEMT) with different gate materials (Ni/Au/Ni or ITO) and absence or presence of the surface passivation layer have shown how this technique can be used as a rapid and effective method to distinguish between the trapping phenomena occurring in the region under the gate and those occurring in the gate - drain access region. In particular we have seen that unpassivated devices have a transconductance peak dispersion, which can be ascribed to the presence of surface traps (absent in passivated devices). On the other hand the presence of a threshold voltage shift (found in the ITO samples) is related to traps below the gate electrode. The presence of traps under the ITO contact has been confirmed by low frequency capacitance - voltage measurements. Also the pulsed measurements have been correlated to electroluminescence characterization of the transistor showing the role of traps in limiting the maximum gate-drain electric field and, consequently, the intensity of the emitted light, related to the equivalent electron temperature.
The combined dynamic IV - electroluminescence measurement technique has been also used in the analysis of state of the art GaN-HEMTs on Silicon substrate. The measurements carried on samples with different gate recess width and same gate length show better performances (in terms of frequency dispersion and gate - drain electric field) for transistors with shorter recess width.
The analysis of defects in GaN-based devices has been carried out also by means of low frequency noise measurements. The purpose of the work on noise was to find a correlation between the intensity of the measured noise and the performances of the device (in particular the breakdown). Several devices have been tested (transistors and transmission line model - TLM) with different realization technology (aluminum content, ohmic contact annealing temperature, composition of ohmic contact electrode). A real correlation between noise in the conductive channel and breakdown has not been found; while measurements on the TLM show a possible relation between ohmic contact specific resistance and noise.
The reliability of several samples has been investigated by means of both long-term stress (1000 h DC life-test) and short-term stress (2 min step-stress).
The long - term stress has been carried out on AlGaN/GaN HEMTs processed on composite SopSiC substrate developed within the European HYPHEN project. These substrates have been realized through the transfer of a thin single crystal silicon layer on the top of a thick polycrystalline silicon carbide wafer. The aim of this project is to provide a valid and less expensive substrate for GaN - based devices in respect to the traditional bulk-SiC substrates. Three stress conditions (different DC biases and different ambient temperatures) have been selected for the test. The results at the end of the stress present good device stability and promising performance; reliability issues found in few samples are linked to the high levels of gate leakage current reached during the stress. This proves that devices failure can be ascribed to the technology used for the realization of transistors and does not appear correlated to the nature of the composite substrate.
With concern the short-term stress, we have studied the influence of gate reverse bias test on the overall behavior of the transistor. This type of accelerated test usually brings to the definition of a critical voltage beyond that the gate leakage current increases drastically up to the failure of the device. In literature the phenomenon is called inverse piezoelectric effect and it is considered related to the lattice strain occurring during the stress. Our study was based on a split wafer experiment adopting passivated AlGaN/GaN HEMTs with different gate metallizations: Ni/Au/Ni, ITO, Ni/ITO. The results obtained suggest that the critical voltage is not related only to the piezoelectric strain, but also the initial gate leakage current of the fresh device plays a role in the degradation process. Moreover the dynamic of the degradation during the test seems to indicate that the ageing process can be ascribe to a defect percolation process in the AlGaN barrier layerL'argomento esposto in questa tesi riguarda uno studio approfondito di dispositivi su eterostruttura AlGaN/GaN. Questo lavoro puo’ essere suddiviso in due argomenti principali: la prima parte riguarda lo studio di trappole e difetti e il loro effetto sulle prestazioni del dispositivo; la seconda parte e’ invece dedicata allo studio dell'affidabilita’ di questo tipo di dispositivi. L'analisi degli effetti trappola e’ basata sulla misurazione impulsata della caratteristica di uscita e della transconduttanza del dispositivo in esame. Le misure eseguite su transistor con diversa composizione dell'elettrodo di gate (Ni/Au/Ni o ITO) e presenza o assenza dello strato di passivazione hanno mostrato come questa tecnica puo’ essere utilizzata come rapido e valido sistema per distinguere tra gli effetti di trappole presenti nella regione sottostante il gate e quelli di trappole nella regione di accesso gate - drain. In dettaglio si e’ visto che dispositivi non passivati presentano una diminuzione del picco della transconduttanza, fenomeno riconducibile alla presenza di trappole superficiali; mentre nel caso di variazione della tensione di soglia (dispositivi con elettrodo di gate in ITO) le trappole sono localizzate nella regione al di sotto del contatto di gate. La presenza di trappole sotto il contatto in ITO e’ stata inoltre confermata da misure di capacita’ vs. tensione a bassa frequenza. Le misure impulsate sono state poi messe in relazione con le misure di elettroluminescenza effettuate sui transistor: questo confronto ha mostrato come le trappole presenti nel dispositivo limitino il massimo campo elettrico tra gate e drain e quindi l'intensita’ della radiazione emessa. Questa metodologia e’ stata poi applicata per l'analisi di dispositivi GaN su silicio caratterizzati da identica lunghezza del contatto di gate ma diversa ampiezza del recesso di gate. Dai risultati ottenuti si puo’ vedere che le prestazioni migliori, in termini di dispersione in frequenza e massimo campo elettrico, si hanno nei dispositivi con recesso piu’ piccolo. L'analisi dei difetti presenti nei dispositivi su GaN e’ stata effettuata anche per mezzo di misure di rumore a bassa frequenza. Lo scopo di questa parte di attivita’ era di trovare una correlazione tra il livello di rumore misurato e le caratteristiche elettriche del dispositivo (in particolare il breakdown). Diversi dispositivi sono stati testati (transistor e transmission line model - TLM) con differenti tecnologie di realizzazione (percentuale di alluminio, temperatura di processo, composizione dell'elettrodo dei contatti ohmici). Una correlazione rumore del canale conduttivo e breakdown non e’ stata trovata; mentre le misure sulle TLM hanno mostrato un possibile legame tra rumore e resistenza specifica del contatto ohmico. L'affidabilita’ dei dispositivi è stata studiata per mezzo di prove di stress a breve (2 min step - stress) e lungo termine (1000 hour). Lo stress a lungo termine e’ stato eseguito su dispositivi AlGaN/GaN processati su substrato composito di tipo SopSiC sviluppato nell'ambito del progetto europeo HYPHEN. Questi substrati sono realizzati tramite il trasferimento di un sottile strato di Silicio monocristallino su uno strato piu’ spesso di Carburo di Silicio policristallino, il loro scopo e’ di rappresentare una valida ed economica alternativa ai substrati in Carburo di Silicio monocristallino. Per questo esperimento sono state individuate tre condizioni a differente polarizzazione e temperatura; i risultati finali presentano una buona stabilita’ dei dispositivi ed inoltre mostrano come i problemi riscontrati durante il test siano riconducibili agli elevati livelli di corrente di perdita del gate. Il degrado dei dispositivi e’ quindi strettamente legato alla tecnologia del processo utilizzato per la realizzazione del transistor e non e’ legata alla natura del substrato. Per quanto riguarda la prova di stress accelerato, si e’ studiato l'effetto sulle prestazioni del dispositivo di elevate tensioni negative applicate al contatto di gate. Questo tipo di test solitamente porta all'individuazione di una tensione critica oltre la quale si verifica un brusco aumento della corrente di gate. Nella letteratura scientifica questo fenomeno e’ indicato come effetto piezoelettrico inverso (inverse piezoelectric effect) ed e’ associato alla creazione di difetti nel reticolo cristallino sottoposto a sollecitazione durante lo stress. Lo studio si e’ basato su un wafer con differenti metallizzazioni di gate (Ni/Au/Ni, ITO, Ni/ITO) e con passivazione dei dispositivi. I risultati ottenuti suggeriscono che la tensione critica non sia legata solo alla tensione che si induce nel reticolo; infatti anche il livello iniziale della corrente di perdita del gate sembra giocare un ruolo nel processo di degradazione. Inoltre l'evoluzione del degrado durante il test sembra indicare che il processo di invecchiamento avvenga per filtrazione dei difetti all'interno della barriera di AlGaN (percolation process)
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Caviness, James A. « Stress biomarkers in a rat model of decompression sickness / ». Download the thesis in PDF, 2005. http://www.lrc.usuhs.mil/dissertations/pdf/Caviness2005.pdf/.
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Milazzo, Lisa. « How resonance Raman spectroscopy can give valuable insights into diverse aspects of heme protein structure and function ». Doctoral thesis, 2019. http://hdl.handle.net/2158/1154362.
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Resonance Raman (RR) spectroscopy complemented by UV-Vis absorption spectroscopy is a very powerful technique to investigate the structure-function relationships of heme proteins, a widely distributed and biological relevant class of proteins which can play different biological functions. Since the protein activity is tightly linked to the structure of the heme active site, my study has been devoted to the investigation of several heme proteins involved in important biological processes, to obtain a comprehensive spectroscopic signature, with the aim to highlight the relationship between the heme pocket architecture and the protein function. The studies were carried out on native proteins and selected site-directed mutants, at both room (298 K) and low (80 K) temperature, at various pH, and in presence of various exogenous ligands, spanning the excitation wavelengths from UV to the visible region.
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Prakash, Shankaran. « Efekt hem arginátu na akutní infekci HIV-1 a na reaktivaci latentní infekce ». Doctoral thesis, 2016. http://www.nusl.cz/ntk/nusl-354437.
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The available antiretroviral compounds can effectively suppress the replication of HIV-1 and block the disease progression. However it is impossible to eradicate the virus from the organism as the HIV-1 integrated in the genome is not affected by the existing anti-HIV-1 drugs. Therefore, new latency reversing agents are being actively developed as part of "shock and kill" therapy to reactivate the provirus and clear the reservoir. Normosang (heme arginate; HA) is a human hemin- containing compound used to treat acute porphyria. Heme is physiologically catabolised by heme oxygenases to form iron (Fe2+ ), carbon monoxide (CO) and biliverdin that is further converted to bilirubin by biliverdin reductase. In this study, we have demonstrated that HA inhibited HIV-1 replication during the acute infection, which was accompanied by the inhibition of reverse transcription. On the other hand, HA synergised with phorbol myristyl acetate (PMA) and reactivated the HIV-1 provirus in ACH-2 cells and the HIV-1 "mini-virus" in Jurkat cell clones A2 and H12. HIV-1 ''mini-virus'' was reactivated also by HA-alone. Further, we have studied the effects of heme degradation products on latent HIV-1 reactivation when added individually. We employed addition of ascorbate to generate Fe2+ , resulting in an increased...
Livres sur le sujet "Reversed heme"
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McWhirter, Darien A. The end of affirmative action : Where do we go from here ? New York : Carol Pub. Group, 1996.
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Lommen, Mathieu. Irma Boom : biography in books : Books in reverse chronological order, 2010-1986 : with comments here and there. Amsterdam : Special Collections UvA, 2010.
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"Prohibition is here to stay" : The Reverend Edward S. Shumaker and the dry crusade in America. Notre Dame, Ind : University of Notre Dame Press, 2009.
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Frazer, J. A. Reverse Engineering : Hype, Hope or Here. Cutter Information Corp, 1991.
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Here by Assignment : The Reverend Archie Ivy Story. BookBaby, 2020.
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Detlefsen, Michael. Formalism. Sous la direction de Stewart Shapiro. Oxford University Press, 2009. http://dx.doi.org/10.1093/oxfordhb/9780195325928.003.0008.
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Viewed properly, formalism is not a single viewpoint concerning the nature of mathematics. Rather, it is a family of related viewpoints sharing a common framework—a framework that has five key elements. Among these is its revision of the traditional classification of the mathematical sciences. From ancient times onward, the dominant view of mathematics was that it was divided into different sciences. Principal among these were a science of magnitude (geometry) and a science of multitude (arithmetic). Traditionally, this division of mathematics was augmented by an ordering of the two parts in terms of their relative basicness and which was to be taken as the more paradigmatically mathematical. Here it was geometry that was given the priority. The formalist outlook typically rejected this traditional ordering of the mathematical sciences. Indeed, from the latter half of the nineteenth century onward, it typically reversed it. This reversal is the first component of the formalist framework.
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Bressan, Paola, et Peter Kramer. The Dungeon Illusion. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780199794607.003.0040.
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A target gray spot looks darker on a white background than on a black one: the contrast illusion. If the target is embedded in a context consisting of black spots on the white background and white spots on the black background, the effect reverses: the dungeon illusion. Whether the dungeon figure produces contrast or contrast reversal depends on which of its three parts (target, context, and background) is gray, black, or white. In some variants, the effect further depends on whether the figures are themselves surrounded by larger white and black regions, implying that even the illumination and wall color of the laboratory might be critical. Here, the various versions of the dungeon illusion are presented and explained with the help of the double-anchoring theory of lightness—that computes the gray shade of objects by “anchoring” them both to their context and to the brightest region in the scene.
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We're All Mad Here : A Dark Alice in Wonderland Reverse Harem. Independently Published, 2022.
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Renmeleon et Ana Maria Selvaggio. From Here to There : Reverse-Engineer the Life You Want into Being. Dragonfly Press Publishing, 2021.
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Waldmann, Carl, Neil Soni et Andrew Rhodes. Respiratory drugs. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780199229581.003.0010.
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Bronchodilators 154Nitric oxide 156Mucolytics 158Surfactant 160Helium–oxygen gas mixtures 162Bronchodilators, as the name suggests, are used in airways disease, particularly in asthma and COPD, to produce a reversal of airway obstruction. An overview of the three main categories is provided here:...
Chapitres de livres sur le sujet "Reversed heme"
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Patel, Shaan S., et Mark A. Frankle. « Hemi, Conventional, and Reverse Total Shoulder Arthroplasty for the Treatment of Proximal Humerus Fractures ». Dans Arthroplasty for the Treatment of Fractures in the Older Patient, 33–52. Cham : Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-94202-5_3.
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Chochinov, Claire A., et Alex N. Nguyen Ba. « Bulk-Fitness Measurements Using Barcode Sequencing Analysis in Yeast ». Dans Methods in Molecular Biology, 399–415. New York, NY : Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2257-5_22.
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AbstractThe use of DNA barcodes for determining changes in genotype frequencies has been instrumental to increase the scale at which we can phenotype strain libraries by using next-generation sequencing technologies. Here, we describe the determination of strain fitness for thousands of yeast strains simultaneously in a single assay using recent innovations that increase the precision of these measurements, such as the inclusion of unique-molecular identifiers (UMIs) and purification by solid-phase reverse immobilization (SPRI) beads.
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Alegria, Guillermo, Christopher C. Moser et P. Leslie Dutton. « Pulsed Electric Field Induced Reverse Electron Transfer from Ground State Bchl2 to the Cytochrome c Hemes in Rps. viridis ». Dans The Photosynthetic Bacterial Reaction Center II, 313–19. Boston, MA : Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3050-3_35.
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Lobo, Daniel. « Formalizing Phenotypes of Regeneration ». Dans Methods in Molecular Biology, 663–79. New York, NY : Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2172-1_36.
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AbstractRegeneration experiments can produce complex phenotypes including morphological outcomes and gene expression patterns that are crucial for the understanding of the mechanisms of regeneration. However, due to their inherent complexity, variability between individuals, and heterogeneous data spreading across the literature, extracting mechanistic knowledge from them is a current challenge. Toward this goal, here we present protocols to unambiguously formalize the phenotypes of regeneration and their experimental procedures using precise mathematical morphological descriptions and standardized gene expression patterns. We illustrate the application of the methodology with step-by-step protocols for planaria and limb regeneration phenotypes. The curated datasets with these methods are not only helpful for human scientists, but they represent a key formalized resource that can be easily integrated into downstream reverse engineering methodologies for the automatic extraction of mechanistic knowledge. This approach can pave the way for discovering comprehensive systems-level models of regeneration.
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Rentz, Niklas, Steven Smyth, Lewe Andersen et Reinhard von Hanxleden. « Extracting Interactive Actor-Based Dataflow Models from Legacy C Code ». Dans Diagrammatic Representation and Inference, 361–77. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-86062-2_37.
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AbstractGraphical actor-based models provide an abstract overview of the flow of data in a system. They are well-established for the model-driven engineering (MDE) of complex software systems and are supported by numerous commercial and academic tools, such as Simulink, LabVIEW or Ptolemy. In MDE, engineers concentrate on constructing and simulating such models, before application code (or at least a large fraction thereof) is synthesized automatically. However, a significant fraction of today’s legacy system has been coded directly, often using the C language. High-level models that give a quick, accurate overview of how components interact are often out of date or do not exist. This makes it challenging to maintain or extend legacy software, in particular for new team members.To address this problem, we here propose to reverse the classic synthesis path of MDE and to synthesize actor-based dataflow models automatically from source code. Here functions in the code get synthesized into nodes that represent actors manipulating data. Second, we propose to harness the modeling-pragmatic approach, which considers visual models not as static artefacts, but allows interactive, flexible views that also link back to textual descriptions. Thus we propose to synthesize actor models that can vary in level of detail and that allow navigation in the source code. To validate and evaluate our proposals, we implemented these concepts for C analysis in the open source, Eclipse-based KIELER project and conducted a small survey.
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Port, Fillip, et Michael Boutros. « Tissue-Specific CRISPR-Cas9 Screening in Drosophila ». Dans Methods in Molecular Biology, 157–76. New York, NY : Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2541-5_7.
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AbstractOver the last century research in Drosophila has resulted in many fundamental contributions to our understanding of the biology of multicellular organisms. Many of these breakthroughs have been based on the identification of novel gene functions in large-scale genetic screens. However, conventional forward-genetic screens have been limited by the random nature of mutagenesis and difficulties in mapping causal mutations, while reverse-genetic RNAi screens suffer from incomplete knockdown of gene expression. Recently developed large-scale CRISPR-Cas9 libraries promise to address these limitations by allowing the induction of targeted mutations in genes with spatial and temporal control. Here, we provide a guide for tissue-specific CRISPR screening in Drosophila, including the characterization of Gal4 UAS-Cas9 lines, selection of sgRNA libraries, and various quality control measures. We also discuss confounding factors that can give rise to false-positive and false-negative results in such experiments and suggest strategies on how to detect and avoid them. Conditional CRISPR screening represents an exciting new approach for functional genomics in vivo and is set to further expand our knowledge of the molecular underpinning of development, homeostasis, and disease.
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Kaiser-Bunbury, Christopher N., et Benno I. Simmons. « Restoration of pollination interactions in communities invaded by non-native plants. » Dans Plant invasions : the role of biotic interactions, 377–90. Wallingford : CABI, 2020. http://dx.doi.org/10.1079/9781789242171.0377.
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Abstract Invasive plant species degrade and homogenize ecosystems worldwide, thereby altering ecosystem processes and function. To mitigate and reverse the impact of invasive plants on pollination, a key ecosystem function, conservation scientists and practitioners restore ecological communities and study the impact of such management interventions on plant-pollinator communities. Here, we describe opportunities and challenges associated with restoring pollination interactions as part of a holistic ecosystem-based restoration approach. We introduce a few general concepts in restoration ecology, and outline best planning and evaluation practices of restoring pollination interactions on the community level. Planning involves the selection of suitable plant species to support diverse pollinator communities, which includes considerations of the benefits and disadvantages of using native vs exotic, and bridge and framework plant species for restoration. We emphasize the central role of scientific- and community-level approaches for the planning phase of pollination restoration. For evaluation purposes, we argue that appropriate network indicators have the advantage of detecting changes in species behaviour with consequences for ecosystem processes and functions before these changes show up in altered species communities. Suitable network metrics may include interaction diversity and evenness, and network measures that describe the distribution of species, such as network and species-level specialization, modularity and motifs. Finally, we discuss the usefulness of the network approach in evaluating the benefits of restoration interventions for pollination interactions, and propose that applied network ecologists take a central role in transferring theory into practice.
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Hell, Wolfram, Kurt Bodewig, Ute Hammer, Christian Kellner, Clemens Klinke, Matthias Mück, Martin Schreiner, Felix Walz et Guido Zielke. « Vision Zero in Germany ». Dans The Vision Zero Handbook, 337–57. Cham : Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-76505-7_13.
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AbstractVision Zero has a central role in traffic safety in Germany. Finally, it was even a relevant point in the coalition treaty from the Federal Governing Parties in the year 2018.It is a unifying theme for safety measures taken on the federal, state, and local levels and in private, nonprofit traffic safety organizations. In later years, cooperation between these different agents has been intensified. Evaluation and measurability are essential in the German approach to Vision Zero. One example of this is the statistical work performed every year to identify “zero cities,” i.e., cities that had zero road fatalities the previous year. A yearly award puts focus on cities that have a particularly long string of zero years, in relation to their size. This is performed on an international level, and cities around the world are incentivized by these recognitions. Munich is used as an example of a city that has recently stepped up its traffic safety work. The city has adopted Vision Zero and followed up this with intensified traffic safety work, including improved data collection, the identification of accident black spots, targeted measures to improve safety in these black spots, safety audits of new infrastructure plans, etc. Before the introduction of new traffic technologies which may have an impact on safety, in-depth technology assessment has to be performed. This is illustrated by an example in which sufficient prior technology assessment did not take place, namely the introduction of e-scooters in Germany. After their introduction, they have turned out to be significantly more dangerous than bicycles, as can be seen from the statistics of fatalities and severe injuries. Proposals are made for measures are needed to reverse this trend, including obligatory use of helmets. The dialogue with neighbor states is also essential. Here the Traffic Expert Society of Medical and Technical Biomechanics, gmttb (Germany, Austria, and Switzerland= D A CH), has initiated to discuss and bundle basic principles of the Vision Zero in three neighbor countries. To promote Vision Zero, gmttb also organizes interdisciplinary yearly conferences with experts from Austria (Vision Zero is a state philosophy) and Switzerland (here named Via Sicura) to bundle strength and adopt ideas together with Swedish and multinational experts. As well as a yearly gmttb Vision Zero Safety Award is granted to motivate people, organizations, and manufacturers to promote good ideas for better traffic safety.
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Hell, Wolfram, Kurt Bodewig, Ute Hammer, Christian Kellner, Clemens Klinke, Matthias Mück, Martin Schreiner, Felix Walz et Guido Zielke. « Vision Zero in Germany ». Dans The Vision Zero Handbook, 1–21. Cham : Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-23176-7_13-1.
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AbstractVision Zero has a central role in traffic safety in Germany. Finally, it was even a relevant point in the coalition treaty from the Federal Governing Parties in the year 2018.It is a unifying theme for safety measures taken on the federal, state, and local levels and in private, nonprofit traffic safety organizations. In later years, cooperation between these different agents has been intensified. Evaluation and measurability are essential in the German approach to Vision Zero. One example of this is the statistical work performed every year to identify “zero cities,” i.e., cities that had zero road fatalities the previous year. A yearly award puts focus on cities that have a particularly long string of zero years, in relation to their size. This is performed on an international level, and cities around the world are incentivized by these recognitions. Munich is used as an example of a city that has recently stepped up its traffic safety work. The city has adopted Vision Zero and followed up this with intensified traffic safety work, including improved data collection, the identification of accident black spots, targeted measures to improve safety in these black spots, safety audits of new infrastructure plans, etc. Before the introduction of new traffic technologies which may have an impact on safety, in-depth technology assessment has to be performed. This is illustrated by an example in which sufficient prior technology assessment did not take place, namely the introduction of e-scooters in Germany. After their introduction, they have turned out to be significantly more dangerous than bicycles, as can be seen from the statistics of fatalities and severe injuries. Proposals are made for measures are needed to reverse this trend, including obligatory use of helmets. The dialogue with neighbor states is also essential. Here the Traffic Expert Society of Medical and Technical Biomechanics, gmttb (Germany, Austria, and Switzerland= D A CH), has initiated to discuss and bundle basic principles of the Vision Zero in three neighbor countries. To promote Vision Zero, gmttb also organizes interdisciplinary yearly conferences with experts from Austria (Vision Zero is a state philosophy) and Switzerland (here named Via Sicura) to bundle strength and adopt ideas together with Swedish and multinational experts. As well as a yearly gmttb Vision Zero Safety Award is granted to motivate people, organizations, and manufacturers to promote good ideas for better traffic safety.
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Walke, Anna, Eric Suero Molina, Walter Stummer et Simone König. « Protoporphyrin IX Analysis from Blood and Serum in the Context of Neurosurgery of Glioblastoma ». Dans Mass Spectrometry [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.95042.
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Protoporphyrin IX (PPIX) is formed from δ-aminolevulinic acid (ALA) during heme biosynthesis. Due to its cyclic tetrapyrrole core structure, it absorbs in the visible region of the electromagnetic spectrum and is thus colored. Both ALA and PPIX have become of great interest to neurosurgery, because in high-grade glioma, ALA diffuses into the tumor and is converted to PPIX. Fluorescence-guided resection (FGR) takes advantage of both the enrichment of PPIX in the tumor and its fluorescent properties, which enable visualization of tumor tissue. ALA-mediated FGR thus maximizes the extent of resection with better prognosis for patients. Tumor cells are able to produce porphyrins naturally or after administration of ALA, which is also reflected in elevated plasma fluorescence of cancer patients. PPIX might thus serve as a biomarker for monitoring of the tumor burden. A liquid chromatography-mass spectrometry (LC-MS)-based method is presented to quantify PPIX in blood and serum in the context of current fluorescence-based diagnostics. The method is able to distinguish between zinc PPIX, a component of red blood cells of importance in the detection of lead poisoning and iron deficiency anemia, and metal-free PPIX. In a proof-of-principle study, it was used to follow a time course of a glioblastoma patient undergoing surgery and confirmed elevated PPIX blood levels before ALA administration. During surgery, these blood levels increased about four-fold. The here developed 10 min reversed-phase LC-target MS method now allows patient screening with high specificity and throughput.
Actes de conférences sur le sujet "Reversed heme"
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Reiner, Richard, Patrick Waltereit, Beatrix Weiss, Matthias Wespel, Rudiger Quay, Michael Schlechtweg, Michael Mikulla et Oliver Ambacher. « Integrated reverse-diodes for GaN-HEMT structures ». Dans 2015 IEEE 27th International Symposium on Power Semiconductor Devices & IC's (ISPSD). IEEE, 2015. http://dx.doi.org/10.1109/ispsd.2015.7123385.
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Sorensen, Charlie, Martin Lindblad Fogsgaard, Michael Noe Christiansen, Mads Kjeldal Graungaard, Jacob Bitcsh Norgaard, Christian Uhrenfeldt et Ionut Trintis. « Conduction, reverse conduction and switching characteristics of GaN E-HEMT ». Dans 2015 IEEE 6th International Symposium on Power Electronics for Distributed Generation Systems (PEDG). IEEE, 2015. http://dx.doi.org/10.1109/pedg.2015.7223051.
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Wang, Yuansheng, Chang Zeng et Ping Lai. « Degradation in AlGaN/GaN HEMT under high temperature reverse bias stress ». Dans 2014 International Conference on Reliability, Maintainability and Safety (ICRMS). IEEE, 2014. http://dx.doi.org/10.1109/icrms.2014.7107161.
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Chengzhan, Li, Liu Jian, Liu Xinyu, Liu Guoguo, Liu Dan, Chen Xiaojuan et He Zhijing. « Effect of Passivation on Increasing of AlGaN/GaN HEMT Gate Reverse Leakage ». Dans 2006 8th International Conference on Solid-State and Integrated Circuit Technology Proceedings. IEEE, 2006. http://dx.doi.org/10.1109/icsict.2006.306568.
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Gorbunov-Possadov, Mikhail Mikhailovich. « Reverse Bibliography ». Dans 23rd Scientific Conference “Scientific Services & Internet – 2021”. Keldysh Institute of Applied Mathematics, 2021. http://dx.doi.org/10.20948/abrau-2021-4s-ceur.
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A reverse bibliography, i.e. a list of referring publications – is a dynamically compiled list of works published after the publication in question and contained a reference to it. Leading publishers of scientific journals, as a rule, post lists of referring publications on the web pages of their articles. In Russia, the placement of lists of citing publications has not yet become the norm, but it is gradually becoming widespread. The reverse bibliography is extremely interesting to the reader since it allows you to find out in which direction the research presented in the original edition is developing. A traditional bibliography, i.e. an ordinary bibliographic list of references, can successfully exist both in a printed publication and online. In contrast, the list of referring publications is essentially an exclusively online, dynamic structure formed “on the fly” on the screen of an online reader. The list of referring publications always brings the reader a fresh current state of accumulated bibliographic data. Publications appearing on the Internet and indexed in bibliographic databases containing a link to the scientific work in question in their bibliography are reflected here almost immediately. The implementation of the list of referring publications in a number of characteristic projects is considered. The terminology used is discussed.
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Rogovin, D., J. Scholl et T. P. Shen. « Two-beam coupling in electromagnetically aligned shaped microparticle suspensions ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oam.1992.tuz35.
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We study the effect of electromagnetically aligning the suspension on the frequency-dependent gain coefficient for energy transfer via NDTWM, and we find that electromagnetic alignment of the particles vastly alters the nonlinear optical characteristics of the suspension. Previous studies focused on static index gratings and predicted a number of novel effects arising from microparticle alignment that manifest themselves in optical phase conjugation. Here we focus on moving optical index gratings and find additional new phenomena that reveal themselves in the gain spectrum for energy transfer via two-beam coupling. Specifically, (1) the magnitude of the low frequency portion of the gain coefficient due to the formation of moving translational index gratings depends on the extent of particle alignment and shape, and the direction of power flow can be reversed. (2) The high frequency portion of the gain coefficient due to the presence of a moving orientational index grating exhibits similar behavior. However, the dynamics associated with reversal of power flow is somewhat different and occurs for different material and electric field parameters.
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Champion, P. M., J. T. Sage et P. Li. « Resonance Raman Studies of Electronic and Vibrational Relaxation Dynamics in Heme Proteins ». Dans International Conference on Ultrafast Phenomena. Washington, D.C. : Optica Publishing Group, 1992. http://dx.doi.org/10.1364/up.1992.tuc6.
Texte intégralRésumé :
We discuss the technique of resonance Raman saturation spectroscopy and present experimental results that probe relaxation processes in heme proteins following electronic excitation in the Soret band. The observable relaxation time scales are limited by the laser excitation rate, kL, rather than by the laser pulse width (~10 ns). Analysis of the data using a model that allows for parallel relaxation channels leads to effective electronic relaxation times for deoxymyoglobin (2ps), ferrocytochrome c (3ps), and deoxyhemoglobin (1ps). The more rapid relaxation times found for hemoglobin and its isolated chains are not currently understood. The Raman depolarization ratio is predicted to increase at high laser flux, due to the preparation of a partially oriented sample by photoselective excitation. Such effects are observed in heme systems and the relaxation times extracted from the depolarization analysis are in agreement with the measurements of Raman intensity saturation. Studies of the asymmetric broadening of the ν 4 mode of cytochrome c at high laser flux, reveal that the lineshapes in the Stokes and anti-Stokes region are inequivalent. Time-reversal symmetry dictates that this broadening is due to an underlying Raman band, associated with an excited electronic state that is populated at high laser flux. Similar linebroadening effects, observed in hemoglobin and myoglobin samples, are also shown to arise from Raman scattering of excited electronic states rather than Rabi broadening1 or anharmonic coupling to vibrationally hot low frequency modes2.
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Lei, Jiacheng, Jin Wei, Gaofei Tang et Kevin J. Chen. « Reverse-blocking AlGaN/GaN normally-off MIS-HEMT with double-recessed gated Schottky drain ». Dans 2018 IEEE 30th International Symposium on Power Semiconductor Devices and ICs (ISPSD). IEEE, 2018. http://dx.doi.org/10.1109/ispsd.2018.8393656.
Texte intégral
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Lu, Meng, Yiqiang Chen, Min Liao, Chang Liu, Shuaizhi Zheng et Kexin Gao. « Degradation mechanism of D-mode GaN HEMT based on high temperature reverse bias stress ». Dans 2021 IEEE Workshop on Wide Bandgap Power Devices and Applications in Asia (WiPDA Asia). IEEE, 2021. http://dx.doi.org/10.1109/wipdaasia51810.2021.9656047.
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Kurumatani, Hiroki, et Seiichiro Katsura. « GaN-HEMT-based three level T-type NPC inverter using reverse-conducting mode in rectifying ». Dans 2017 IEEE 26th International Symposium on Industrial Electronics (ISIE). IEEE, 2017. http://dx.doi.org/10.1109/isie.2017.8001548.
Texte intégralRapports d'organisations sur le sujet "Reversed heme"
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Pshezhetskiy, Dmitry, Tanveer Alam et Heba Alshaker. Unsynchronised Cardioversion as a Cause of Ventricular Tachycardia in a Patient with Atrial Fibrillation. Nature Library, novembre 2020. http://dx.doi.org/10.47496/nl.ccr.2020.01.02.
Texte intégralRésumé :
Background: Synchronised cardioversion (SC) is used to terminate tachycardic arrhythmia by applying electric current to the thorax. SC is synchronised to the R wave of the cardiac cycle and ventricular tachycardia (VT) or ventricular fibrillation (VF) can occur if an electrical shock is provided in a nonsynchronised way. Case Presentation: Here we present a case of a 66-year-old man who had elective cardioversion for atrial fibrillation worsened by severe left ventricular impairment. A manual defibrillator was used for the cardioversion, which, after the first synchronised shock, reverted to defibrillator mode. An unsynchronised shock was administered and induced VT, which was reverted to sinus rhythm with a defibrillation shock. Conclusion: When using manual defibrillator for SC, the machine needs to be set to a synchronised mode. The synchronisation to the R wave needs to be checked before every shock.
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Schiller, Brandon, Tara Hutchinson et Kelly Cobeen. Cripple Wall Small-Component Test Program : Dry Specimens (PEER-CEA Project). Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, novembre 2020. http://dx.doi.org/10.55461/vsjs5869.
Texte intégralRésumé :
This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER) and funded by the California Earthquake Authority (CEA). The overall project is titled “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER–CEA Project.” The overall objective of the PEER–CEA Project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measures and documents seismic performance of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Three primary tasks support the earthquake loss-modeling effort. They are: (1) the development of ground motions and loading protocols that accurately represent the diversity of seismic hazard in California; (2) the execution of a suite of quasi-static cyclic experiments to measure and document the performance of cripple wall and sill anchorage deficiencies to develop and populate loss models; and (3) nonlinear response history analysis on cripple wall-supported buildings and their components. This report is a product of Working Group 4: Testing, whose central focus was to experimentally investigate the seismic performance of retrofitted and existing cripple walls. This present report focuses on non-stucco or “dry” exterior finishes. Paralleled by a large-component test program conducted at the University of California, Berkeley (UC Berkeley) [Cobeen et al. 2020], the present report involves two of multiple phases of small-component tests conducted at University of California San Diego (UC San Diego). Details representative of era-specific construction–specifically the most vulnerable pre-1960s construction–are of predominant focus in the present effort. Parameters examined are cripple wall height, finish style, gravity load, boundary conditions, anchorage, and deterioration. This report addresses all eight specimens in the second phase of testing and three of the six specimens in the fourth phase of testing. Although conducted in different testing phases, their results are combined here to co-locate observations regarding the behavior of all dry finished specimens. Experiments involved imposition of combined vertical loading and quasi-static reversed cyclic lateral load onto eleven cripple walls. Each specimen was 12 ft in length and 2-ft or 6-ft in height. All specimens in this report were constructed with the same boundary conditions on the top, bottom, and corners of the walls. Parameters addressed in this report include: dry exterior finish type (shiplap horizontal lumber siding, shiplap horizontal lumber siding over diagonal lumber sheathing, and T1-11 wood structural panels), cripple wall height, vertical load, and the retrofitted condition. Details of the test specimens, testing protocol (including instrumentation), and measured as well as physical observations are summarized. Results from these experiments are intended to support advancement of numerical modeling tools, which ultimately will inform seismic loss models capable of quantifying the reduction of loss achieved by applying state-of-practice retrofit methods as identified in FEMA P-1100 Vulnerability-Base Seismic Assessment and Retrofit of One- and Two-Family Dwellings.
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Schiller, Brandon, Tara Hutchinson et Kelly Cobeen. Cripple Wall Small-Component Test Program : Wet Specimens II (PEER-CEA Project). Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, novembre 2020. http://dx.doi.org/10.55461/ldbn4070.
Texte intégralRésumé :
This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER and funded by the California Earthquake Authority (CEA). The overall project is titled “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER–CEA Project.” The overall objective of the PEER–CEA Project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measure and assess the effectiveness of seismic retrofit to reduce the risk of damage and associated losses (repair costs) of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Tasks that support and inform the loss-modeling effort are: (1) collecting and summarizing existing information and results of previous research on the performance of wood-frame houses; (2) identifying construction features to characterize alternative variants of wood-frame houses; (3) characterizing earthquake hazard and ground motions at representative sites in California; (4) developing cyclic loading protocols and conducting laboratory tests of cripple wall panels, wood-frame wall subassemblies, and sill anchorages to measure and document their response (strength and stiffness) under cyclic loading; and (5) the computer modeling, simulations, and the development of loss models as informed by a workshop with claims adjustors. This report is a product of Working Group 4 (WG4): Testing, whose central focus was to experimentally investigate the seismic performance of retrofitted and existing cripple walls. This report focuses stucco or “wet” exterior finishes. Paralleled by a large-component test program conducted at the University of California, Berkeley (UC Berkeley) [Cobeen et al. 2020], the present study involves two of multiple phases of small-component tests conducted at the University of California San Diego (UC San Diego). Details representative of era-specific construction, specifically the most vulnerable pre-1960s construction, are of predominant focus in the present effort. Parameters examined are cripple wall height, finish style, gravity load, boundary conditions, anchorage, and deterioration. This report addresses the third phase of testing, which consisted of eight specimens, as well as half of the fourth phase of testing, which consisted of six specimens where three will be discussed. Although conducted in different phases, their results are combined here to co-locate observations regarding the behavior of the second phase the wet (stucco) finished specimens. The results of first phase of wet specimen tests were presented in Schiller et al. [2020(a)]. Experiments involved imposition of combined vertical loading and quasi-static reversed cyclic lateral load onto ten cripple walls of 12 ft long and 2 or 6 ft high. One cripple wall was tested with a monotonic loading protocol. All specimens in this report were constructed with the same boundary conditions on the top and corners of the walls as well as being tested with the same vertical load. Parameters addressed in this report include: wet exterior finishes (stucco over framing, stucco over horizontal lumber sheathing, and stucco over diagonal lumber sheathing), cripple wall height, loading protocol, anchorage condition, boundary condition at the bottom of the walls, and the retrofitted condition. Details of the test specimens, testing protocol, including instrumentation; and measured as well as physical observations are summarized in this report. Companion reports present phases of the tests considering, amongst other variables, impacts of various boundary conditions, stucco (wet) and non-stucco (dry) finishes, vertical load, cripple wall height, and anchorage condition. Results from these experiments are intended to support advancement of numerical modeling tools, which ultimately will inform seismic loss models capable of quantifying the reduction of loss achieved by applying state-of-practice retrofit methods as identified in FEMA P-1100,Vulnerability-Base Seismic Assessment and Retrofit of One- and Two-Family Dwellings.
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Murray, Chris, Keith Williams, Norrie Millar, Monty Nero, Amy O'Brien et Damon Herd. A New Palingenesis. University of Dundee, novembre 2022. http://dx.doi.org/10.20933/100001273.
Texte intégralRésumé :
Robert Duncan Milne (1844-99), from Cupar, Fife, was a pioneering author of science fiction stories, most of which appeared in San Francisco’s Argonaut magazine in the 1880s and ’90s. SF historian Sam Moskowitz credits Milne with being the first full-time SF writer, and his contribution to the genre is arguably greater than anyone else including Stevenson and Conan Doyle, yet it has all but disappeared into oblivion. Milne was fascinated by science. He drew on the work of Scottish physicists and inventors such as James Clark Maxwell and Alexander Graham Bell into the possibilities of electromagnetic forces and new communications media to overcome distances in space and time. Milne wrote about visual time-travelling long before H.G. Wells. He foresaw virtual ‘tele-presencing’, remote surveillance, mobile phones and worldwide satellite communications – not to mention climate change, scientific terrorism and drone warfare, cryogenics and molecular reengineering. Milne also wrote on alien life forms, artificial immortality, identity theft and personality exchange, lost worlds and the rediscovery of extinct species. ‘A New Palingenesis’, originally published in The Argonaut on July 7th 1883, and adapted in this comic, is a secular version of the resurrection myth. Mary Shelley was the first scientiser of the occult to rework the supernatural idea of reanimating the dead through the mysterious powers of electricity in Frankenstein (1818). In Milne’s story, in which Doctor S- dissolves his terminally ill wife’s body in order to bring her back to life in restored health, is a striking, further modernisation of Frankenstein, to reflect late-nineteenth century interest in electromagnetic science and spiritualism. In particular, it is a retelling of Shelley’s narrative strand about Frankenstein’s aborted attempt to shape a female mate for his creature, but also his misogynistic ambition to bypass the sexual principle in reproducing life altogether. By doing so, Milne interfused Shelley’s updating of the Promethean myth with others. ‘A New Palingenesis’ is also a version of Pygmalion and his male-ordered, wish-fulfilling desire to animate his idealised female sculpture, Galatea from Ovid’s Metamorphoses, perhaps giving a positive twist to Orpheus’s attempt to bring his corpse-bride Eurydice back from the underworld as well? With its basis in spiritualist ideas about the soul as a kind of electrical intelligence, detachable from the body but a material entity nonetheless, Doctor S- treats his wife as an ‘intelligent battery’. He is thus able to preserve her personality after death and renew her body simultaneously because that captured electrical intelligence also carries a DNA-like code for rebuilding the individual organism itself from its chemical constituents. The descriptions of the experiment and the body’s gradual re-materialisation are among Milne’s most visually impressive, anticipating the X-raylike anatomisation and reversal of Griffin’s disappearance process in Wells’s The Invisible Man (1897). In the context of the 1880s, it must have been a compelling scientisation of the paranormal, combining highly technical descriptions of the Doctor’s system of electrically linked glass coffins with ghostly imagery. It is both dramatic and highly visual, even cinematic in its descriptions, and is here brought to life in the form of a comic.