Pablo Pérez - Academia.edu (original) (raw)

Papers by Pablo Pérez

Research paper thumbnail of Common Missense Variant in the Glucokinase Regulatory Protein Gene Is Associated With Increased Plasma Triglyceride and C-Reactive Protein but Lower Fasting Glucose Concentrations

Diabetes, 2008

OBJECTIVE-Using the genome-wide association approach, we recently identified the glucokinase regu... more OBJECTIVE-Using the genome-wide association approach, we recently identified the glucokinase regulatory protein gene (GCKR, rs780094) region as a novel quantitative trait locus for plasma triglyceride concentration in Europeans. Here, we sought to study the association of GCKR variants with metabolic phe-notypes, including measures of glucose homeostasis, to evaluate the GCKR locus in samples of non-European ancestry and to finemap across the associated genomic interval.

Research paper thumbnail of Polycyclic Aromatic Hydrocarbon Contribution to the Infrared Output Energy of the Universe at z ~= 2

Astrophysical Journal Supplement Series, 2004

We present an updated phenomenological galaxy evolution model to fit the Spitzer 24, 70 and 160 µ... more We present an updated phenomenological galaxy evolution model to fit the Spitzer 24, 70 and 160 µm number counts as well as all the previous mid and far infrared observations. Only a minor change of the co-moving luminosity density distribution in the previous model (Lagache, Dole, Puget 2003), combined with a slight modification of the starburst template spectra mainly between 12 and 30 µm, are required to fit all the data available. We show that the peak in the MIPS 24 µm counts is dominated by galaxies with redshift between 1 and 2, with a non negligible contribution from the z ≥ 2 galaxies (∼ 30% at S=0.2 mJy). The very close agreement between the model and number counts at 15 and 24 µm strikingly implies that (1) the PAHs (Policyclic Aromatic Hydrocarbons) features remain prominent in the redshift band 0.5 to 2.5 and (2) the IR energy output has to be dominated by ∼3 10 11 L to ∼3 10 12 L galaxies from redshift 0.5 to 2.5. Combining Spitzer with the Infrared Space Observatory (ISO) deep cosmological surveys gives for the first time an unbiased view of the infrared Universe from z=0 to z=2.5.

Research paper thumbnail of The chronic intake of a Mediterranean diet enriched in virgin olive oil, decreases nuclear transcription factor κB activation in peripheral blood mononuclear cells from healthy men

Atherosclerosis, 2007

Objetive: Nuclear transcription factor B (NF-B) plays a key role in the inflammatory response and... more Objetive: Nuclear transcription factor B (NF-B) plays a key role in the inflammatory response and can be modulate by dietary fat. We have examined the effect of three diets, with different fat composition, on the activation of NF-B on peripheral blood mononuclear cells (PBMCs). Methods: Sixteen healthy men followed three 4-week diets, in a randomised crossover design: a Western diet, rich in saturated fat (SFA) [22% SFA, 12% monounsaturated fat (MUFA) and 0, 4 ␣-linolenic acid]; a Mediterranean diet [<10% SFA, 24% MUFA and 0.4% ␣-linolenic acid], and a low fat diet enriched in ␣-linolenic acid [<10% SFA, 12% MUFA and 2% ␣-linolenic acid]. NF-B (electrophoretic mobility shift assay) in mononuclear cells and plasma concentrations (ELISA) of soluble vascular cellular adhesion molecule 1 (VCAM-1) were examined after either diets. Results: Western diet increased 2.7-fold NF-B compared with the Mediterranean diet (p = 0.038) and 1.79-fold with the ␣-linolenic acid diet (p = 0.07). No differences were found between the last two. Furthermore, an increase on plasma VCAM-1 was observed with the Western diet (p < 0.05). Conclusions: The Mediterranean diet diminished NF-B activation in mononuclear cells, compared with Western diet, supporting its cardioprotective properties. The effect of the n − 3 enriched diet was intermediate.

Research paper thumbnail of Absolute Calibration and Characterization of the Multiband Imaging Photometer for Spitzer. II. 70 micron Imaging

The absolute calibration and characterization of the Multiband Imaging Photometer for Spitzer (MI... more The absolute calibration and characterization of the Multiband Imaging Photometer for Spitzer (MIPS) 70 µm coarse-and fine-scale imaging modes are presented based on over 2.5 years of observations. Accurate photometry (especially for faint sources) requires two simple processing steps beyond the standard data reduction to remove long-term detector transients. Point spread function (PSF) fitting photometry is found to give more accurate flux densities than aperture photometry. Based on the PSF fitting photometry, the calibration factor shows no strong trend with flux density, background, spectral type, exposure time, or time since anneals. The coarse-scale calibration sample includes observations of stars with flux densities from 22 mJy to 17 Jy, on backgrounds from 4 to 26 MJy sr −1 , and with spectral types from B to M. The coarse-scale calibration is 702 ± 35 MJy sr −1 MIPS70 −1 (5% uncertainty) and is based on measurements of 66 stars. The instrumental units of the MIPS 70 µm coarse-and fine-scale imaging modes are called MIPS70 and MIPS70F, respectively. The photometric repeatability is calculated to be 4.5% from two stars measured during every MIPS campaign and includes variations on all time scales probed. The preliminary fine-scale calibration factor is 2894 ± 294 MJy sr −1 MIPS70F −1 (10% uncertainty) based on 10 stars. The uncertainty in the coarseand fine-scale calibration factors are dominated by the 4.5% photometric repeatability and the small sample size, respectively. The 5σ, 500 s sensitivity of the coarse-scale observations is 6-8 mJy. This work shows that the MIPS 70 µm array produces accurate, well calibrated photometry and validates the MIPS 70 µm operating strategy, especially the use of frequent stimulator flashes to track the changing responsivities of the Ge:Ga detectors.

Research paper thumbnail of Reduction Algorithms for the Multiband Imaging Photometer for Spitzer

Publications of The Astronomical Society of The Pacific, 2005

The first six months of flight data from the Multiband Imaging Photometer for Spitzer (MIPS) were... more The first six months of flight data from the Multiband Imaging Photometer for Spitzer (MIPS) were used to test MIPS reduction algorithms based on extensive preflight laboratory data and modeling. The underlying approach for the preflight algorithms has been found to be sound, but some modifications have improved the performance. The main changes are scan mirror dependent flat fields at 24 µm, hand processing to remove the time dependent stim flash latents and fast/slow response variations at 70 µm, and the use of asteroids and other sources instead of stars for flux calibration at 160 µm due to a blue "leak." The photometric accuracy of flux measurpements is currently 5%, 10%, and 20% at 24, 70, and 160 µm, respectively. These numbers are expected to improve as more flight data are analyzed and data reduction algorithms refined.

Research paper thumbnail of Spitzer View on the Evolution of Star-forming Galaxies from z = 0 to z ~ 3

Astrophysical Journal, 2005

We use a 24 µm selected sample containing more than 8,000 sources to study the evolution of star-... more We use a 24 µm selected sample containing more than 8,000 sources to study the evolution of star-forming galaxies in the redshift range from z = 0 to z ∼ 3. We obtain photometric redshifts for most of the sources in our survey using a method based on empirically-built templates spanning from ultraviolet to mid-infrared wavelengths. The accuracy of these redshifts is better than 10% for 80% of the sample. The derived redshift distribution of the sources detected by our survey peaks at around z = 0.6 − 1.0 (the location of the peak being affected by cosmic variance), and decays monotonically from z ∼ 1 to z ∼ 3. We have fitted infrared luminosity functions in several redshift bins in the range 0 < z 3. Our results constrain the density and/or luminosity evolution of infrared-bright star-forming galaxies. The typical infrared luminosity (L * ) decreases by an order of magnitude from z ∼ 2 to the present. The cosmic star formation rate (SFR) density goes as (1 + z) 4.0±0.2 from z = 0 to z = 0.8. From z = 0.8 to z ∼ 1.2, the SFR density continues rising with a smaller slope. At 1.2 < z 3, the cosmic SFR density remains roughly constant. The SFR density is dominated at low redshift (z 0.5) by galaxies which are not very luminous in the infrared (L TIR < 10 11 L ⊙ , where L TIR is the total infrared luminosity, integrated from 8 to 1000 µm). The contribution from luminous and ultraluminous infrared galaxies (L TIR > 10 11 L ⊙ ) to the total SFR density increases steadily from z ∼ 0 up to z ∼ 2.5, forming at least half of the newly-born stars by z ∼ 1.5. Ultraluminous infrared galaxies (L TIR > 10 12 L ⊙ ) play a rapidly increasing role for z 1.3.

Research paper thumbnail of Common Missense Variant in the Glucokinase Regulatory Protein Gene Is Associated With Increased Plasma Triglyceride and C-Reactive Protein but Lower Fasting Glucose Concentrations

Diabetes, 2008

OBJECTIVE-Using the genome-wide association approach, we recently identified the glucokinase regu... more OBJECTIVE-Using the genome-wide association approach, we recently identified the glucokinase regulatory protein gene (GCKR, rs780094) region as a novel quantitative trait locus for plasma triglyceride concentration in Europeans. Here, we sought to study the association of GCKR variants with metabolic phe-notypes, including measures of glucose homeostasis, to evaluate the GCKR locus in samples of non-European ancestry and to finemap across the associated genomic interval.

Research paper thumbnail of Polycyclic Aromatic Hydrocarbon Contribution to the Infrared Output Energy of the Universe at z ~= 2

Astrophysical Journal Supplement Series, 2004

We present an updated phenomenological galaxy evolution model to fit the Spitzer 24, 70 and 160 µ... more We present an updated phenomenological galaxy evolution model to fit the Spitzer 24, 70 and 160 µm number counts as well as all the previous mid and far infrared observations. Only a minor change of the co-moving luminosity density distribution in the previous model (Lagache, Dole, Puget 2003), combined with a slight modification of the starburst template spectra mainly between 12 and 30 µm, are required to fit all the data available. We show that the peak in the MIPS 24 µm counts is dominated by galaxies with redshift between 1 and 2, with a non negligible contribution from the z ≥ 2 galaxies (∼ 30% at S=0.2 mJy). The very close agreement between the model and number counts at 15 and 24 µm strikingly implies that (1) the PAHs (Policyclic Aromatic Hydrocarbons) features remain prominent in the redshift band 0.5 to 2.5 and (2) the IR energy output has to be dominated by ∼3 10 11 L to ∼3 10 12 L galaxies from redshift 0.5 to 2.5. Combining Spitzer with the Infrared Space Observatory (ISO) deep cosmological surveys gives for the first time an unbiased view of the infrared Universe from z=0 to z=2.5.

Research paper thumbnail of The chronic intake of a Mediterranean diet enriched in virgin olive oil, decreases nuclear transcription factor κB activation in peripheral blood mononuclear cells from healthy men

Atherosclerosis, 2007

Objetive: Nuclear transcription factor B (NF-B) plays a key role in the inflammatory response and... more Objetive: Nuclear transcription factor B (NF-B) plays a key role in the inflammatory response and can be modulate by dietary fat. We have examined the effect of three diets, with different fat composition, on the activation of NF-B on peripheral blood mononuclear cells (PBMCs). Methods: Sixteen healthy men followed three 4-week diets, in a randomised crossover design: a Western diet, rich in saturated fat (SFA) [22% SFA, 12% monounsaturated fat (MUFA) and 0, 4 ␣-linolenic acid]; a Mediterranean diet [<10% SFA, 24% MUFA and 0.4% ␣-linolenic acid], and a low fat diet enriched in ␣-linolenic acid [<10% SFA, 12% MUFA and 2% ␣-linolenic acid]. NF-B (electrophoretic mobility shift assay) in mononuclear cells and plasma concentrations (ELISA) of soluble vascular cellular adhesion molecule 1 (VCAM-1) were examined after either diets. Results: Western diet increased 2.7-fold NF-B compared with the Mediterranean diet (p = 0.038) and 1.79-fold with the ␣-linolenic acid diet (p = 0.07). No differences were found between the last two. Furthermore, an increase on plasma VCAM-1 was observed with the Western diet (p < 0.05). Conclusions: The Mediterranean diet diminished NF-B activation in mononuclear cells, compared with Western diet, supporting its cardioprotective properties. The effect of the n − 3 enriched diet was intermediate.

Research paper thumbnail of Absolute Calibration and Characterization of the Multiband Imaging Photometer for Spitzer. II. 70 micron Imaging

The absolute calibration and characterization of the Multiband Imaging Photometer for Spitzer (MI... more The absolute calibration and characterization of the Multiband Imaging Photometer for Spitzer (MIPS) 70 µm coarse-and fine-scale imaging modes are presented based on over 2.5 years of observations. Accurate photometry (especially for faint sources) requires two simple processing steps beyond the standard data reduction to remove long-term detector transients. Point spread function (PSF) fitting photometry is found to give more accurate flux densities than aperture photometry. Based on the PSF fitting photometry, the calibration factor shows no strong trend with flux density, background, spectral type, exposure time, or time since anneals. The coarse-scale calibration sample includes observations of stars with flux densities from 22 mJy to 17 Jy, on backgrounds from 4 to 26 MJy sr −1 , and with spectral types from B to M. The coarse-scale calibration is 702 ± 35 MJy sr −1 MIPS70 −1 (5% uncertainty) and is based on measurements of 66 stars. The instrumental units of the MIPS 70 µm coarse-and fine-scale imaging modes are called MIPS70 and MIPS70F, respectively. The photometric repeatability is calculated to be 4.5% from two stars measured during every MIPS campaign and includes variations on all time scales probed. The preliminary fine-scale calibration factor is 2894 ± 294 MJy sr −1 MIPS70F −1 (10% uncertainty) based on 10 stars. The uncertainty in the coarseand fine-scale calibration factors are dominated by the 4.5% photometric repeatability and the small sample size, respectively. The 5σ, 500 s sensitivity of the coarse-scale observations is 6-8 mJy. This work shows that the MIPS 70 µm array produces accurate, well calibrated photometry and validates the MIPS 70 µm operating strategy, especially the use of frequent stimulator flashes to track the changing responsivities of the Ge:Ga detectors.

Research paper thumbnail of Reduction Algorithms for the Multiband Imaging Photometer for Spitzer

Publications of The Astronomical Society of The Pacific, 2005

The first six months of flight data from the Multiband Imaging Photometer for Spitzer (MIPS) were... more The first six months of flight data from the Multiband Imaging Photometer for Spitzer (MIPS) were used to test MIPS reduction algorithms based on extensive preflight laboratory data and modeling. The underlying approach for the preflight algorithms has been found to be sound, but some modifications have improved the performance. The main changes are scan mirror dependent flat fields at 24 µm, hand processing to remove the time dependent stim flash latents and fast/slow response variations at 70 µm, and the use of asteroids and other sources instead of stars for flux calibration at 160 µm due to a blue "leak." The photometric accuracy of flux measurpements is currently 5%, 10%, and 20% at 24, 70, and 160 µm, respectively. These numbers are expected to improve as more flight data are analyzed and data reduction algorithms refined.

Research paper thumbnail of Spitzer View on the Evolution of Star-forming Galaxies from z = 0 to z ~ 3

Astrophysical Journal, 2005

We use a 24 µm selected sample containing more than 8,000 sources to study the evolution of star-... more We use a 24 µm selected sample containing more than 8,000 sources to study the evolution of star-forming galaxies in the redshift range from z = 0 to z ∼ 3. We obtain photometric redshifts for most of the sources in our survey using a method based on empirically-built templates spanning from ultraviolet to mid-infrared wavelengths. The accuracy of these redshifts is better than 10% for 80% of the sample. The derived redshift distribution of the sources detected by our survey peaks at around z = 0.6 − 1.0 (the location of the peak being affected by cosmic variance), and decays monotonically from z ∼ 1 to z ∼ 3. We have fitted infrared luminosity functions in several redshift bins in the range 0 < z 3. Our results constrain the density and/or luminosity evolution of infrared-bright star-forming galaxies. The typical infrared luminosity (L * ) decreases by an order of magnitude from z ∼ 2 to the present. The cosmic star formation rate (SFR) density goes as (1 + z) 4.0±0.2 from z = 0 to z = 0.8. From z = 0.8 to z ∼ 1.2, the SFR density continues rising with a smaller slope. At 1.2 < z 3, the cosmic SFR density remains roughly constant. The SFR density is dominated at low redshift (z 0.5) by galaxies which are not very luminous in the infrared (L TIR < 10 11 L ⊙ , where L TIR is the total infrared luminosity, integrated from 8 to 1000 µm). The contribution from luminous and ultraluminous infrared galaxies (L TIR > 10 11 L ⊙ ) to the total SFR density increases steadily from z ∼ 0 up to z ∼ 2.5, forming at least half of the newly-born stars by z ∼ 1.5. Ultraluminous infrared galaxies (L TIR > 10 12 L ⊙ ) play a rapidly increasing role for z 1.3.