| 1. |
- Wood-Vasey, W. M., et al.
(författare)
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Observational constraints on the nature of dark energy : First cosmological results from the ESSENCE supernova survey
- 2007
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 666:2, s. 694-715
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Forskningsöversikt (refereegranskat)abstract
- We present constraints on the dark energy equation-of-state parameter, w = P/(rho c(2)), using 60 SNe Ia fromthe ESSENCE supernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat universe. By including constraints on (Omega(M), w) from baryon acoustic oscillations, we obtain a value for a static equation-of-state parameter w = -1:05(-0.12)(+0: 13) (stat 1 sigma) +/- 0: 13 (sys) and Omega(M) = 0:274(-0.020)(+0:033) (stat 1 sigma) with a bestfit chi(2)/dof of 0.96. These results are consistent with those reported by the Supernova Legacy Survey from the first year of a similar program measuring supernova distances and redshifts. We evaluate sources of systematic error that afflict supernova observations and present Monte Carlo simulations that explore these effects. Currently, the largest systematic with the potential to affect our measurements is the treatment of extinction due to dust in the supernova host galaxies. Combining our set of ESSENCE SNe Ia with the first-results Supernova Legacy Survey SNe Ia, we obtain a joint constraint of w = -1:07(-0: 09)(+0:09) (stat 1 sigma) +/- 0: 13 ( sys), Omega(M) 0:267(-0:028)(+0:028) (stat 1 sigma) with a best-fit chi(2)/dof of 0.91. The current global SN Ia data alone rule out empty (Omega(M) = 0), matter-only Omega(M) = 0: 3, and Omega(M) = 1 universes at > 4.5 sigma. The current SN Ia data are fully consistent with a cosmological constant.
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| 2. |
- Miknaitis, G., et al.
(författare)
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The ESSENCE supernova survey : Survey optimization, observations, and supernova photometry
- 2007
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 666:2, s. 674-693
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Forskningsöversikt (refereegranskat)abstract
- We describe the implementation and optimization of the ESSENCE supernova survey, which we have undertaken to measure the dark energy equation-of-state parameter, w = P/(rho c(2)). We present a method for optimizing the survey exposure times and cadence to maximize our sensitivity to w for a given fixed amount of telescope time. For our survey on the CTIO 4 m telescope, measuring the luminosity distances and redshifts for supernovae at modest redshifts (z approximate to 0: 5 +/- 0: 2) is optimal for determining w. We describe the data analysis pipeline based on using reliable and robust image subtraction to find supernovae automatically and in nearly real time. Since making cosmological inferences with supernovae relies crucially on accurate measurement of their apparent brightnesses, we describe our efforts to establish a thorough calibration of the CTIO 4 m telescope's natural photometric system. In its first four years, ESSENCE has discovered and spectroscopically confirmed 102 Type Ia supernovae, at redshifts from 0.10 to 0.78, identified through an impartial, effective methodology for spectroscopic classification and redshift determination. We present the resulting light curves for all of the Type Ia supernovae found by ESSENCE and used in our measurement of w, presented in a companion paper by Wood-Vasey and coworkers.
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| 3. |
- Fraga, MF, et al.
(författare)
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Epigenetic differences arise during the lifetime of monozygotic twins
- 2005
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 102:30, s. 10604-10609
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Tidskriftsartikel (refereegranskat)abstract
- Monozygous twins share a common genotype. However, most monozygotic twin pairs are not identical; several types of phenotypic discordance may be observed, such as differences in susceptibilities to disease and a wide range of anthropomorphic features. There are several possible explanations for these observations, but one is the existence of epigenetic differences. To address this issue, we examined the global and locus-specific differences in DNA methylation and histone acetylation of a large cohort of monozygotic twins. We found that, although twins are epigenetically indistinguishable during the early years of life, older monozygous twins exhibited remarkable differences in their overall content and genomic distribution of 5-methylcytosine DNA and histone acetylation, affecting their gene-expression portrait. These findings indicate how an appreciation of epigenetics is missing from our understanding of how different phenotypes can be originated from the same genotype.
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| 4. |
- Cano-Aguilera, I., et al.
(författare)
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Use of hydride generation-atomic absorption spectrometry to determine the effects of hard ions, iron salts and humic substances on arsenic sorption to sorghum biomass
- 2005
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Ingår i: Microchemical Journal. - : Elsevier BV. - 0026-265X. ; 81:1, s. 57-60
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Tidskriftsartikel (refereegranskat)abstract
- At present, there is a great interest in studying new sorbent materials for the removal of arsenic from aqueous solutions because of its high toxicity and adverse effects on human health. In previous research, sorghum biomass was found to be an efficient and economic sorbent for the removal of arsenic from aqueous solutions. In this investigation, the effects of CaCl2, MgCl 2, FeSO4, MgSO4, Fe(NO3) 3, and humic substances (peat moss, humin and humic acids) on arsenic binding to sorghum biomass were evaluated. Among these compounds, only iron salts were found to positively increase the sorption of arsenic to sorghum biomass. In addition, the sorption equilibrium was reached faster when the reaction mixture contained iron salts. However, an overall reduction of 21% of arsenic sorption to sorghum biomass was observed in the presence of MgSO 4. This interference may be due to the presence of sulfate ions, instead of the hard cations, that could be in competition with As for the same interaction sites or ligands. Peat moss, humins and humic acid, extracted from sphagnum peat moss, significantly decreased the arsenic sorption to sorghum biomass.
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| 5. |
- Haque, Nazmul, et al.
(författare)
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Characteristics of arsenic adsorption to sorghum biomass
- 2007
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 1873-3336 .- 0304-3894. ; 145:1-2, s. 30-35
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Tidskriftsartikel (refereegranskat)abstract
- The development of efficient and economic new adsorbent materials for the removal of arsenic from groundwater is a priority in regions where human health is directly affected by elevated arsenic concentrations. Adsorption of arsenic on sorghum biomass (SB) was investigated for the removal of arsenic from aqueous solutions. Potentiometric titrations and FTIR analysis evidenced two potential binding sites associated with carboxyl and hydroxyl groups. Batch experiments were carried out to determine the equilibrium time for arsenic adsorption to SB. The effect of pH on arsenic adsorption to SB was investigated for a pH range of 2.0-10.0. A strong influence of pH was demonstrated with a maximum removal of arsenic at pH 5.0. Freundlich and Langmuir isotherms were applied to equilibrium data. The Freundlich model fitted the equilibrium data and provided evidence for site heterogeneity at the binding surface. Column experiments were performed to obtain the breakthrough curves for both non-immobilized sorghum biomass and immobilized sorghum biomass.
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| 6. |
- Haque, Nazmul, et al.
(författare)
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Sorption of arsenic on sorghum biomass: a case study
- 2005
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Ingår i: Natural Arsenic in Groundwater. - : CRC Press. - 9780415367004 ; , s. 247-253
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Large scale, field experiments were conducted for the removal of arsenic from the groundwater of a well located in Guanajuato, Mexico region using non-immobilized sorghum biomass (NISB) as a sorbent, which was found highly efficient to adsorb As in previous laboratory experiments. The columns were run under gravity and pump flow conditions. Removal of arsenic under pump flow was slightly higher than the gravity flow due to the steady-state flow conditions. The maximum arsenic accumulation measured was 3.2 and 3.3 mg of As/g of NISB for gravity and pump flow conditions, respectively. To determine the optimal hydraulic detention time, columns were operated under different flow rates and the maximum sorption occurred at a flow rate of 10 mL/min. Columns of different dimensions were run to obtain the optimal design parameter between surface loading and volumetric loading of the system. The optimal sorption condition can be achieved through the volumetric design of the system.
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| 7. |
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| 8. |
- Carrero, JJ, et al.
(författare)
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Appetite disorders in uremia
- 2008
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Ingår i: Journal of renal nutrition : the official journal of the Council on Renal Nutrition of the National Kidney Foundation. - : Elsevier BV. - 1532-8503. ; 18:1, s. 107-113
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Tidskriftsartikel (refereegranskat)
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| 9. |
- Jacquemin, B, et al.
(författare)
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Association between modelled traffic related air pollution (NO2) and asthma score in ECHRS.
- 2009
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Ingår i: European Respiratory Journal. - : The European Respiratory Society. - 0903-1936 .- 1399-3003. ; 34:4, s. 834-842
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this analysis is to study the association between air pollution and asthma among adults. For this goal, a previously developed "asthma score" was used.Persons aged 25-44 years were randomly selected (1991-1993) and followed up (2000-2002) within the European Community Respiratory Health Survey (ECRHS-I and II). The asthma score was defined from 0 to 5, based on positive answers to symptoms reported for the last 12 months: wheeze/breathlessness, chest tightness, dyspnoea at rest, dyspnoea after exercise, and woken by dyspnoea. Participants' home addresses were linked to outdoor modelled NO2 estimates for 2001. Negative binomial regression was used to model the asthma score.The score from ECRHS-II was positively associated with NO2 (Ratio of the Mean asthma Score (RMS) 1.23, 95% Confidence Intervals (CI): 1.09-1.38 for an increase of 10 microg.m(-3)). After excluding participants with asthma and symptoms at baseline, the association remained (RMS 1.25, 95%CI: 1.05-1.51) and was particularly high among those reporting a high score in ECRHS-II. The latter probably reflects incident cases of asthma.Our results suggest that traffic-related pollution causes asthma symptoms and possibly asthma incidence in adults. The asthma score offers an alternative to investigate the course and aetiology of asthma in adults.
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| 10. |
- Paulino, M., et al.
(författare)
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Studies of trypanocidal (inhibitory) power of naphthoquinones: : evaluation of quantum chemical molecular descriptors for structure-activity relationships
- 2008
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Ingår i: European Journal of Medicinal Chemistry. - : Elsevier BV. - 0223-5234. ; 43:10, s. 2238-2246
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Tidskriftsartikel (refereegranskat)abstract
- Electronic, lipophilic and steric descriptors included in QSAR-2D and -3D are analyzed for a set of ortho- and para-naphthoquinones that have proved to be powerful oxidative agents with potent trypanocidal activities specially against Leptomonas seymouri and Trypanosoma cruzi. Electronic properties are calculated by means of semiempirical (PM3), ab initio (HF/3-21G) and density functional theory (B3LYP/6-31 + G*) methodologies. Three different electronic states, neutral quinones, hydroquinones and semiquinones, are studied to investigate if any one of them are statistically related with the biological activities. The best correlations were obtained at the B3LYP level of theory because it includes electronic correlation. The QSAR-2D indicates that the best trypanocidal growth inhibitors are molecules in the semiquinone electronic state, with the following properties: (a) high negative value of EHOMO, (b) high negative charge in the oxygen atoms of the carbonyl groups, (c) high positive charge in the carbon atom of one of carbonyl moieties and (d) high electronegativity (χ). In a complementary way, the QSAR-3D indicates that the electrostatic field correlates with trypanocidal activity and the presence of bulk moieties would increase activity. The idea of comparing the three electronic states may prove to be of most importance in the general strategy to the design of new trypanocidal drugs. In fact, the experimental results showed that semiquinone is the one really statistically relevant indicating a clear connection between biochemical and theoretical aspects. Finally, we demonstrated that to be a good anti-trypanosomatid compound, the molecule must be a good electron acceptor to reach easily the essential semiquinone state. We expect that the present results motivate new experimental as well as theoretical investigations that confirm our findings.
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