805 research outputs found
Femtoscopy in Relativistic Heavy Ion Collisions: Two Decades of Progress
Analyses of two-particle correlations have provided the chief means for
determining spatio-temporal characteristics of relativistic heavy ion
collisions. We discuss the theoretical formalism behind these studies and the
experimental methods used in carrying them out. Recent results from RHIC are
put into context in a systematic review of correlation measurements performed
over the past two decades. The current understanding of these results is
discussed in terms of model comparisons and overall trends.Comment: 49 pages, 16 figures; to appear in Annual Review of Nuclear and
Particle Science; final version includes minor updates in text, a few
references added, and two figures updated; Figures and numerical data tables
available at http://www.physics.ohio-state.edu/~lisa/FemtoscopyReview2005
Examining the association between physical characteristics of green space and land Surface temperature: A case study of Ulsan, Korea
The rapid increase of impervious surfaces and the dense development that accompanies urban growth has reduced the amount of green space in urban landscapes and increased urban surface temperatures. Accordingly, the greening of urban spaces has been proposed as one approach to mitigating urban heat island (UHI) effects. To find the most practical green space design for reducing land surface temperatures (LSTs), we explored the effects of the physical characteristics of green spaces on cooling intensity and distance. The physical characteristics of green spaces were defined as shape, size, Normalized Difference Vegetation Index (NDVI), and the land-use type of their surroundings. LANDSAT 8 images were used to examine 30 green spaces in Ulsan, Korea. The analytical results showed that the cooling effect was mainly observed within 120 m of a green area and that the intensity of the cooling effects did not exceed 3.0 K. A belt-shaped green space had a greater cooling distance compared to a compact green space. We also found that the NDVI and size of a green space had a positive but non-linear association with cooling intensity.ope
Improvement of Lipids and Reduction of Oxidative Stress With Octacosanol After Taekwondo Training
Athletes in combat sports undergo rapid changes in body weight prior to competition in order to gain a size advantage over their opponent. However, these large weight changes with concomitant high-intensity exercise training create poor lipid profiles and high levels of oxidative stress, which can be detrimental to health and sport performance. Therefore, the purpose of this study was to investigate the ability of the nutritional supplement octacosanol to combat the physiological detriments that occur in taekwondo players during rapid weight loss with high-intensity exercise training. Methods: A total of 26 male taekwondo players were randomly divided into 2 groups: An experimental group performed a 5% weight-loss and taekwondo training program with 40-mg octacosanol intake (OCT; n = 13) for 6 d, and a control group performed the same weight-loss and taekwondo training program with a placebo (CON; n = 13). Results: There were significant (P \u3c .05) group × time interactions for low-density lipoprotein and triglycerides, which significantly decreased (Δ18 [5] mg/dL and Δ80 [7] mg/dL, respectively), and high-density lipoprotein, which significantly increased (Δ10 [7] mg/dL), in the OCT group compared with the CON group. There were also significant (P \u3c .05) group × time interactions for superoxide dismutase (SOD), glutathione peroxidase (GPx), and malondialdehyde (MDA), with SOD increasing (Δ226 [121] U/gHb) in the OCT group, while GPx decreased (Δ20 [13] U/gHb) and MDA increased (Δ72 [0.04] nmol/mL) in the CON group. Conclusion: These results suggest that octacosanol may be a beneficial supplement to protect against the poor cholesterol levels and oxidative stress that occurs during taekwondo training
Structural effects in UO thin films irradiated with fission-energy Xe ions
Uranium dioxide thin films have been successfully grown on LSAT (AlLaOSrTa) substrates by reactive magnetron sputtering. Irradiation by 92 MeV Xe ions to simulate fission damage that occurs within nuclear fuels caused microstructural and crystallographic changes. Initially flat and continuous thin films were produced by magnetron sputtering with a root mean square roughness of 0.35 nm determined by AFM. After irradiation, this roughness increased to 60-70 nm, with the films developing discrete microstructural features: small grains (~3 m), along with larger circular (up to 40 m) and linear formations with non-uniform composition according to the SEM, AFM and EDX results. The irradiation caused significant restructuring of the UO films that was manifested in significant filmsubstrate mixing, observed through EDX analysis. Diffusion of Al from the substrate into the film in unirradiated samples was also observed.Engineering and Physical Sciences Research Council (Grant ID: EP/ I036400/1), Radioactive Waste Management Ltd (formerly the Radioactive Waste Management Directorate of the UK Nuclear Decommissioning Authority, contract NPO004411A-EPS02), Russian Foundation for Basic Research (projects 13-03-90916), CSAR, Grand Accelélérateur National d’Ions Lourds (GANIL) Caen France, French Network EMIR, CIMAP-CIRIL, M.V.Lomonosov Moscow State University Program of Development, CKP FMI IPCE RA
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Structural effects in UO thin films irradiated with U ions
This work presents the results of a detailed structural characterisation of irradiated and unirradiated single crystal thin films of UO. Thin films of UO were produced by reactive magnetron sputtering onto (0 0 1), (1 1 0) and (1 1 1) single crystal yttria-stabilised zirconia (YSZ) substrates. Half of the samples were irradiated with 110 MeV U ions to fluences of 5 10, 5 10 and 5 10 ions/cm to induce radiation damage, with the remainder kept for reference measurements. It was observed that as-produced UO films adopted the crystallographic orientation of their YSZ substrates. The irradiation fluences used in this study however, were not sufficient to cause any permanent change in the crystalline nature of UO. It has been demonstrated that the effect of epitaxial re-crystallisation of the induced radiation damage can be quantified in terms of kernel average misorientation (KAM) and different crystallographic orientations of UO respond differently to ion irradiation.The irradiation experiment was performed at the Grand Accélérateur National d’Ions Lourds (GANIL) Caen, France, and supported by the French Network EMIR. A.J. Popel acknowledges funding from the UK EPSRC (grant EP/ I036400/1) and Radioactive Waste Management Ltd (formerly the Radioactive Waste Management Directorate of the UK Nuclear Decommissioning Authority, contract NPO004411A-EPS02)
The Escherichia coli transcriptome mostly consists of independently regulated modules
Underlying cellular responses is a transcriptional regulatory network (TRN) that modulates gene expression. A useful description of the TRN would decompose the transcriptome into targeted effects of individual transcriptional regulators. Here, we apply unsupervised machine learning to a diverse compendium of over 250 high-quality Escherichia coli RNA-seq datasets to identify 92 statistically independent signals that modulate the expression of specific gene sets. We show that 61 of these transcriptomic signals represent the effects of currently characterized transcriptional regulators. Condition-specific activation of signals is validated by exposure of E. coli to new environmental conditions. The resulting decomposition of the transcriptome provides: a mechanistic, systems-level, network-based explanation of responses to environmental and genetic perturbations; a guide to gene and regulator function discovery; and a basis for characterizing transcriptomic differences in multiple strains. Taken together, our results show that signal summation describes the composition of a model prokaryotic transcriptome
Chromosomal radiosensitivity in head and neck cancer patients: evidence for genetic predisposition?
The association between chromosomal radiosensitivity and genetic predisposition to head and neck cancer was investigated in this study. In all, 101 head and neck cancer patients and 75 healthy control individuals were included in the study. The G2 assay was used to measure chromosomal radiosensitivity. The results demonstrated that head and neck cancer patients had a statistically higher number of radiation-induced chromatid breaks than controls, with mean values of 1.23 and 1.10 breaks per cell, respectively (P<0.001). Using the 90th percentile of the G2 scores of the healthy individuals as a cutoff value for chromosomal radiosensitivity, 26% of the cancer patients were radiosensitive compared with 9% of the healthy controls (P=0.008). The mean number of radiation-induced chromatid breaks and the proportion of radiosensitive individuals were highest for oral cavity cancer patients (1.26 breaks per cell, 38%) and pharynx cancer patients (1.27 breaks per cell, 35%). The difference between patients and controls was most pronounced in the lower age group (⩽50 years, 1.32 breaks per cell, 38%) and in the non- and light smoking patient group (⩽10 pack-years, 1.28 breaks per cell, 46%). In conclusion, enhanced chromosomal radiosensitivity is a marker of genetic predisposition to head and neck cancer, and the genetic contribution is highest for oral cavity and pharynx cancer patients and for early onset and non- and light smoking patients
Steady-state modulation of voltage-gated K+ channels in rat arterial smooth muscle by cyclic AMP-dependent protein kinase and protein phosphatase 2B
Voltage-gated potassium channels (Kv) are important regulators of membrane potential in vascular smooth muscle cells, which is integral to controlling intracellular Ca2+ concentration and regulating vascular tone. Previous work indicates that Kv channels can be modulated by receptor-driven alterations of cyclic AMP-dependent protein kinase (PKA) activity. Here, we demonstrate that Kv channel activity is maintained by tonic activity of PKA. Whole-cell recording was used to assess the effect of manipulating PKA signalling on Kv and ATP-dependent K+ channels of rat mesenteric artery smooth muscle cells. Application of PKA inhibitors, KT5720 or H89, caused a significant inhibition of Kv currents. Tonic PKA-mediated activation of Kv appears maximal as application of isoprenaline (a β-adrenoceptor agonist) or dibutyryl-cAMP failed to enhance Kv currents. We also show that this modulation of Kv by PKA can be reversed by protein phosphatase 2B/calcineurin (PP2B). PKA-dependent inhibition of Kv by KT5720 can be abrogated by pre-treatment with the PP2B inhibitor cyclosporin A, or inclusion of a PP2B auto-inhibitory peptide in the pipette solution. Finally, we demonstrate that tonic PKA-mediated modulation of Kv requires intact caveolae. Pre-treatment of the cells with methyl-β-cyclodextrin to deplete cellular cholesterol, or adding caveolin-scaffolding domain peptide to the pipette solution to disrupt caveolae-dependent signalling each attenuated PKA-mediated modulation of the Kv current. These findings highlight a novel, caveolae-dependent, tonic modulatory role of PKA on Kv channels providing new insight into mechanisms and the potential for pharmacological manipulation of vascular tone
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