479 research outputs found
Compact Pulsed-Power System for Transient Plasma Ignition
The article of record as published may be found at http://dx.doi.org10.1109/TPS.2009.2024672The use of a compact solid-state pulse generator and compact igniters for transient plasma ignition in a pulse detonation engine (PDE) is reported and compared with previous results using a pseudospark pulse generator and threaded rod electrode. Transient plasma is attractive as a technology for the ignition of PDEs and other engine applications because it results in reductions in ignition delay and has been shown to ignite leaner mixtures which allows for lower specific fuel consumption, high-repetition rates, high-altitude operation, and reduced NOx emissions. It has been applied effectively to the ignition of PDEs as well as internal combustion engines. Nonequilibrium transient plasma discharges are produced by applying high-voltage nanosecond pulses that generate streamers, which generate radicals and other electronically excited species over a volume. The pulse generator used is in this experiment is capable of delivering 180 mJ into a 200-Ω load, in the form of a 60-kV 12-ns pulse. Combined with transient plasma igniters comparable with traditional spark plugs, the system was successfully tested in a PDE, resulting in similar ignition delays to those previously reported while using a smaller electrode geometry and delivering an order of magnitude less energy.Office of Naval Researc
Direct evidence from high-field magnetotransport for a dramatic change of quasiparticle character in van der Waals ferromagnet Fe<sub>3−</sub>GeTe<sub>2</sub>
Magnetometry and magnetoresistance (MR) data taken on the van der Waals ferromagnet Fe3−GeTe2 (FGT) reveal three distinct contributions to the MR: a linear negative component, a contribution from closed Fermi-surface orbits, and an enhancement proportional to the square of the applied magnetic field which is linked to a noncoplanar spin arrangement. Contrary to earlier studies on FGT, by accounting for the field dependence of the anomalous Hall effect, we find that the ordinary Hall coefficient decreases markedly below 80 K, indicating a significant change in character of the electrons and holes on the Fermi-surface at this temperature. The resulting altered ground state eventually causes the Hall coefficient to reverse sign at 35 K. Our Hall data support the proposal that Kondo-lattice behavior develops in this -electron material below 80 K. Additional evidence comes from the negative linear component of the MR, which arises from electron-magnon scattering with an atypical temperature dependence attributable to the onset of Kondo screening
Experimental Evidence for Heavy-Atom Tunneling in the Ring-Opening of Cyclopropylcarbinyl Radical from Intramolecular 12C/13C Kinetic Isotope Effects
Article on experimental evidence for heavy-atom tunneling in the ring-opening of cyclopropylcarbinyl radical from intramolecular 12C/13C kinetic isotope effects
A whole-blood transcriptome meta-analysis identifies gene expression signatures of cigarette smoking
Cigarette smoking is a leading modifiable cause of death worldwide. We hypothesized that cigarette smoking induces extensive transcriptomic changes that lead to target-organ damage and smoking-related diseases. We performed a metaanalysis of transcriptome-wide gene expression using whole blood-derived RNA from 10,233 participants of European ancestry in six cohorts (including 1421 current and 3955 former smokers) to identify associations between smoking and altered gene expression levels. At a false discovery rate (FDR) < 0.1, we identified 1270 differentially expressed genes in current vs. never smokers, and 39 genes in former vs. never smokers. Expression levels of 12 genes remained elevated up to 30 years after smoking cessation, suggesting that the molecular consequence of smoking may persist for decades. Gene ontology analysis revealed enrichment of smoking-related genes for activation of platelets and lymphocytes, immune response, and apoptosis. Many of the top smoking-related differentially expressed genes, including LRRN3 and GPR15, have DNA methylation loci in promoter regions that were recently reported to be hypomethylated among smokers. By linking differential gene expression with smoking-related disease phenotypes, we demonstrated that stroke and pulmonary function show enrichment for smoking-related gene expression signatures. Mediation analysis revealed the expression of several genes (e.g. ALAS2) to be putative mediators of the associations between smoking and inflammatory biomarkers (IL6 and C-re
New genetic loci implicated in fasting glucose homeostasis and their impact on type 2 diabetes risk.
Levels of circulating glucose are tightly regulated. To identify new loci influencing glycemic traits, we performed meta-analyses of 21 genome-wide association studies informative for fasting glucose, fasting insulin and indices of beta-cell function (HOMA-B) and insulin resistance (HOMA-IR) in up to 46,186 nondiabetic participants. Follow-up of 25 loci in up to 76,558 additional subjects identified 16 loci associated with fasting glucose and HOMA-B and two loci associated with fasting insulin and HOMA-IR. These include nine loci newly associated with fasting glucose (in or near ADCY5, MADD, ADRA2A, CRY2, FADS1, GLIS3, SLC2A2, PROX1 and C2CD4B) and one influencing fasting insulin and HOMA-IR (near IGF1). We also demonstrated association of ADCY5, PROX1, GCK, GCKR and DGKB-TMEM195 with type 2 diabetes. Within these loci, likely biological candidate genes influence signal transduction, cell proliferation, development, glucose-sensing and circadian regulation. Our results demonstrate that genetic studies of glycemic traits can identify type 2 diabetes risk loci, as well as loci containing gene variants that are associated with a modest elevation in glucose levels but are not associated with overt diabetes
Hydrophilic antioxidant compounds in orange juice from different fruit cultivars: Composition and antioxidant activity evaluated by chemical and cellular based (Saccharomyces cerevisiae) assays
Antioxidant capacity was evaluated by a cellular model (Saccharomyces cerevisiae) and chemical
methods (FRAP, TEAC and total phenols by Folin-Ciocalteu assay) in the hydrophilic fraction (phenolic
compounds and ascorbic acid) of orange juices (OJs) from six varieties (Midknight, Delta Seedless, Rohde
Red, Seedless, Early and clone Sambiasi), harvested in two seasons. The contents of phenolic compounds
and ascorbic acid analyzed, respectively, by UPLC and HPLC were 370.04 76.97 mg/L and
52.05 6.69 mg/100 mL. Variety and season significantly influenced (p < 0.05) composition and antioxidant
capacity. TEAC and FRAP values correlated well with individual hydrophilic compounds (R2 > 0.991) but no
correlation with cellular assay was observed. An increase in survival rates between 23% and 38% was
obtained, excepting for two varieties that showed no activity (Rohde Red and Seedless). Narirutin, naringin-d,
ferulic acid-d2, didymin, neoeriocitrin and sinapic acid hexose and caffeic acid-d1 were the phenolic
compounds which contributed to survival rates (R2 = 0.979, p < 0.01
GWAS of longevity in CHARGE consortium confirms APOE and FOXO3 candidacy.
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This article is open access.The genetic contribution to longevity in humans has been estimated to range from 15% to 25%. Only two genes, APOE and FOXO3, have shown association with longevity in multiple independent studies.We conducted a meta-analysis of genome-wide association studies including 6,036 longevity cases, age ≥90 years, and 3,757 controls that died between ages 55 and 80 years. We additionally attempted to replicate earlier identified single nucleotide polymorphism (SNP) associations with longevity.In our meta-analysis, we found suggestive evidence for the association of SNPs near CADM2 (odds ratio [OR] = 0.81; p value = 9.66 × 10(-7)) and GRIK2 (odds ratio = 1.24; p value = 5.09 × 10(-8)) with longevity. When attempting to replicate findings earlier identified in genome-wide association studies, only the APOE locus consistently replicated. In an additional look-up of the candidate gene FOXO3, we found that an earlier identified variant shows a highly significant association with longevity when including published data with our meta-analysis (odds ratio = 1.17; p value = 1.85×10(-10)).We did not identify new genome-wide significant associations with longevity and did not replicate earlier findings except for APOE and FOXO3. Our inability to find new associations with survival to ages ≥90 years because longevity represents multiple complex traits with heterogeneous genetic underpinnings, or alternatively, that longevity may be regulated by rare variants that are not captured by standard genome-wide genotyping and imputation of common variants.Netherlands Organisation of Scientific Research NWO Investments
175.010.2005.011
911-03-012
Research Institute for Diseases in the Elderly
014-93-015
RIDE2
Netherlands Genomics Initiative (NGI)/Netherlands Organisation for Scientific Research (NWO)
050-060-810
Erasmus Medical Center
Erasmus University, Rotterdam
Netherlands Organization for the Health Research and Development (ZonMw)
Research Institute for Diseases in the Elderly (RIDE)
Ministry of Education, Culture and Science
Ministry for Health, Welfare and Sports
European Commission (DG XII)
Municipality of Rotterdam
National Institutes of Health
National Institute on Aging (NIA)
R01 AG005407
R01 AR35582
R01 AR35583
R01 AR35584
R01 AG005394
R01 AG027574
R01 AG027576
AG023629
R01AG29451
U01AG009740
RC2 AG036495
RC4 AG039029
P30AG10161
R01AG17917
R01AG15819
R01AG30146
U01-AG023755
U19-AG023122
NHLBI
HHSN 268201200036C
HHSN268200800007C
N01HC55222
N01HC85079
N01HC85080
N01HC85081
N01HC85082
N01HC85083
N01HC 85086
HL080295
HL087652
HL105756
National Institute of Neurological Disorders and Stroke (NINDS)
National Center for Advancing Translational Sciences, CTSI
UL1TR000124
National Institute of Diabetes and Digestive and Kidney Disease Diabetes Research Center (DRC)
DK063491
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
National Center for Research Resources (NCRR)
NIH Roadmap for Medical Research
U01 AR45580
U01 AR45614
U01 AR45632
U01 AR45647
U01 AR45654
U01 AR45583
U01 AG18197
U01-AG027810
UL1 RR024140
NIAMS
R01-AR051124
RC2ARO58973
National Heart, Lung and Blood Institute's Framingham Heart Study
N01-HC-25195
Affymetrix, Inc
N02-HL-6-4278
Robert Dawson Evans Endowment of the Department of Medicine at Boston University School of Medicine
Boston Medical Center
National Institute of Arthritis, Musculoskeletal and Skin Diseases
NIA
R01 AR/AG 41398
NIH
N01-AG-12100
NIA Intramural Research Program
Hjartavernd (the Icelandic Heart Association)
Althingi (the Icelandic Parliament)
Illinois Department of Public Health
Translational Genomics Research Institute
Italian Ministry of Health
ICS110.1/RF97.71
U.S. National Institute on Aging
263 MD 9164
263 MD 821336
Intramural Research Program of the NIH, National Institute on Aging
1R01AG028321
1R01HL09257
A meta-analysis of gene expression signatures of blood pressure and hypertension
Genome-wide association studies (GWAS) have uncovered numerous genetic variants (SNPs) that are associated with blood pressure (BP). Genetic variants may lead to BP changes by acting on intermediate molecular phenotypes such as coded protein sequence or gene expression, which in turn affect BP variability. Therefore, characterizing genes whose expression is associated with BP may reveal cellular processes involved in BP regulation and uncover how transcripts mediate genetic and environmental effects on BP variability. A meta-analysis of results from six studies of global gene expression profiles of BP and hypertension in whole blood was performed in 7017 individuals who were not receiving antihypertensive drug treatment. We identified 34 genes that were differentially expressed in relation to BP (Bonferroni-corrected p<0.05). Among these genes, FOS and PTGS2 have been previously reported to be involved in BP-related processes; the others are novel. The top BP signature genes in aggregate explain 5%-9% of inter-individual variance in BP. Of note, rs3184504 in SH2B3, which was also reported in GWAS to be associated with BP, was found to be a trans regulator of the expression of 6 of the transcripts we found to be associated with BP (FOS, MYADM, PP1R15A, TAGAP, S100A10, and FGBP2). Gene set enrichment analysis suggested that the BP-related global gene expression changes include genes involved in inflammatory response and apoptosis pathways. Our study provides new insights into molecular mechanisms underlying BP regulation, and suggests novel transcriptomic markers for the treatment and prevention of hypertension
Domestication Syndrome in Caimito (Chrysophyllum cainito L.): Fruit and Seed Characteristics
Domestication Syndrome in Caimito (Chrysophyllum cainitoL.): Fruit and Seed Characteristics: The process of domestication is understudied and poorly known for many tropical fruit tree crops. The star apple or caimito tree (Chrysophyllum cainito L., Sapotaceae) is cultivated throughout the New World tropics for its edible fruits. We studied this species in central Panama, where it grows wild in tropical moist forests and is also commonly cultivated in backyard gardens. Using fruits collected over two harvest seasons, we tested the hypothesis that cultivated individuals of C. cainito show distinctive fruit and seed characteristics associated with domestication relative to wild types. We found that cultivated fruits were significantly and substantially larger and allocated more to pulp and less to exocarp than wild fruits. The pulp of cultivated fruits was less acidic; also, the pulp had lower concentrations of phenolics and higher concentrations of sugar. The seeds were larger and more numerous and were less defended with phenolics in cultivated than in wild fruits. Discriminant Analysis showed that, among the many significant differences, fruit size and sugar concentration drove the great majority of the variance distinguishing wild from cultivated classes. Variance of pulp phenolics among individuals was significantly higher among wild trees than among cultivated trees, while variance of fruit mass and seed number was significantly higher among cultivated trees. Most traits showed strong correlations between years. Overall, we found a clear signature of a domestication syndrome in the fruits of cultivated caimito in Panama
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