Alvaro Cea - Academia.edu (original) (raw)

Papers by Alvaro Cea

Astrophysical Journal, 2011

We report on the observation of γ-rays above 25 GeV from the Crab pulsar (PSR B0532+21) using the... more We report on the observation of γ-rays above 25 GeV from the Crab pulsar (PSR B0532+21) using the MAGIC I telescope. Two data sets from observations during the winter period 2007/2008 and 2008/2009 are used. In order to discuss the spectral shape from 100 MeV to 100 GeV, one year of public Fermi Large Area Telescope (Fermi-LAT) data are also analyzed to complement the MAGIC data. The extrapolation of the exponential cutoff spectrum determined with the Fermi-LAT data is inconsistent with MAGIC measurements, which requires a modification of the standard pulsar emission models. In the energy region between 25 and 100 GeV, the emission in the P1 phase (from -0.06 to 0.04, location of the main pulse) and the P2 phase (from 0.32 to 0.43, location of the interpulse) can be described by power laws with spectral indices of -3.1 ± 1.0stat ± 0.3syst and -3.5 ± 0.5stat ± 0.3syst, respectively. Assuming an asymmetric Lorentzian for the pulse shape, the peak positions of the main pulse and the interpulse are estimated to be at phases -0.009 ± 0.007 and 0.393 ± 0.009, while the full widths at half-maximum are 0.025 ± 0.008 and 0.053 ± 0.015, respectively.

Journal of Hypertension, 2006

Epidemiological data on the incidence and prevalence of cardiovascular disease in chronic renal f... more Epidemiological data on the incidence and prevalence of cardiovascular disease in chronic renal failure are scant The objective of the present study is to assess the relationship between renal function, measured by the estimated glomerular filtration rate, and the presence of early or established cardiovascular disease, in a population of hypertensives from primary care. Cross-sectional, multicentre study carried out in primary care centres all over Spain. Hypertensive subjects, older than 55 years, were included. In all of them a structured interview including cardiovascular risk factors or disease was performed. Blood pressure was measured following a standard procedure, and serum biochemistry and an electrocardiogram were obtained. Renal function was estimated using the abbreviated MDRD (Modification of Diet in Renal Disease Study Group) equation. For each glomerular filtration rate stratum the odds ratio and 95% confidence interval (CI) of left ventricular hypertrophy or cardiovascular disease were calculated, adjusted by confounding variables. A total of 13 687 patients (mean age 68.1 years, women 55.4%, diabetics 30.6%, body mass index 28.6 kg/m2) were included. Of these, 26.4% had established cardiovascular diseases and 20.3% electrocardiographic left ventricular hypertrophy. The average serum creatinine was 1.01 mg/dl, creatinine clearance 70.0 ml/min, and glomerular filtration rate 74.0 ml/min per 1.73 m2. Thirty-three patients (0.24%) had glomerular filtration rate < 5 ml/min per 1.73 m2; 89 (0.65%) from 15 to 29; 3745 (27.36%) from 30 to 59; 7798 (56.97%) from 60 to 89; and 2019 (14.75%) higher than 89 ml/min per 1.73 m2. In a multiple regression analysis, after adjusting by age, sex, body mass index, diabetes, systolic and diastolic blood pressure, and smoking, a lower glomerular filtration rate was associated with a higher prevalence of left ventricular hypertrophy. Likewise, a reduction in the glomerular filtration rate was also associated with a higher prevalence of cardiovascular disease. In hypertensive patients from primary care, the prevalence of cardiovascular disease is inversely proportional to the level of renal function. Estimated glomerular filtration is easy to determine and complements evaluation of the hypertensive patient.

Revista Espanola De Cardiologia, 2009

To determine the prevalence of a low high-density lipoprotein cholesterol (HDL-C) concentration i... more To determine the prevalence of a low high-density lipoprotein cholesterol (HDL-C) concentration in 11 042 hypertensive Spanish women aged ≥55 years, to identify factors associated with a low concentration, and to evaluate its relationship with cardiovascular disease (CVD).

Astroparticle Physics, 2009

The Cherenkov light flashes produced by Extensive Air Showers are very short in time. A high band... more The Cherenkov light flashes produced by Extensive Air Showers are very short in time. A high bandwidth and fast digitizing readout, therefore, can minimize the influence of the background from the light of the night sky, and improve the performance in Cherenkov telescopes. The time structure of the Cherenkov image can further be used in single-dish Cherenkov telescopes as an additional parameter to reduce the background from unwanted hadronic showers. A description of an analysis method which makes use of the time information and the subsequent improvement on the performance of the MAGIC telescope (especially after the upgrade with an ultra fast 2 GSamples/s digitization system in February 2007) will be presented. The use of timing information in the analysis of the new MAGIC data reduces the background by a factor two, which in turn results in an enhancement of about a factor 1.4 of the flux sensitivity to point-like sources, as tested on observations of the Crab Nebula.

Journal of Allergy and Clinical Immunology, 2004

Hereditary angioedema (HAE), a rare but life-threatening condition, manifests as acute attacks of... more Hereditary angioedema (HAE), a rare but life-threatening condition, manifests as acute attacks of facial, laryngeal, genital, or peripheral swelling or abdominal pain secondary to intra-abdominal edema. Resulting from mutations affecting C1 esterase inhibitor (C1-INH), inhibitor of the first complement system component, attacks are not histamine-mediated and do not respond to antihistamines or corticosteroids. Low awareness and resemblance to other disorders often delay diagnosis; despite availability of C1-INH replacement in some countries, no approved, safe acute attack therapy exists in the United States. The biennial C1 Esterase Inhibitor Deficiency Workshops resulted from a European initiative for better knowledge and treatment of HAE and related diseases. This supplement contains work presented at the third workshop and expanded content toward a definitive picture of angioedema in the absence of allergy. Most notably, it includes cumulative genetic investigations; multinational laboratory diagnosis recommendations; current pathogenesis hypotheses; suggested prophylaxis and acute attack treatment, including home treatment; future treatment options; and analysis of patient subpopulations, including pediatric patients and patients whose angioedema worsened during pregnancy or hormone administration. Causes and management of acquired angioedema and a new type of angioedema with normal C1-INH are also discussed. Collaborative patient and physician efforts, crucial in rare diseases, are emphasized. This supplement seeks to raise awareness and aid diagnosis of HAE, optimize treatment for all patients, and provide a platform for further research in this rare, partially understood disorder.

Revista Espanola De Cardiologia, 2006

trophy (LVH) is the earliest manifestation of cardiac damage in hypertension. Its appearance is a... more trophy (LVH) is the earliest manifestation of cardiac damage in hypertension. Its appearance is associated with a poor cardiovascular prognosis. The objectives of this study were to determine the prevalence of electrocardiographic LVH and to assess the epidemiological characteristics of hypertensive patients receiving primary care.

Astronomy & Astrophysics, 2011

Results. We find that the VHE gamma-ray emission detected in 2006 and 2007 challenges standard on... more Results. We find that the VHE gamma-ray emission detected in 2006 and 2007 challenges standard one-zone model, based on relativistic electrons in a jet scattering broad line region photons, while the other studied models fit the observed spectral energy distribution more satisfactorily.

Science, 2008

The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has det... more The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has detected very-high-energy gamma rays from a giant flare of the distant Quasi-Stellar Radio Source (in short: radio quasar) 3C 279, at a distance of more than 5 billion light-years (a redshift of 0.536). No quasar has been observed previously in very-high-energy gamma radiation, and this is also the most distant object detected emitting gamma rays above 50 gigaelectron volts. Since high-energy gamma rays may be stopped by interacting with the diffuse background light in the universe, the observations by MAGIC imply a low amount for such light, consistent with that known from galaxy counts.

Reservados todos los detechos. Quedan rigurosamente prohibidas, sin la autorización escrita de lo... more Reservados todos los detechos. Quedan rigurosamente prohibidas, sin la autorización escrita de los titulares del copyright, bajo las sanciones establecidas en las leyes, la reproducción total o parcial de esta obra por cualquier medio o procedimiento, comprendidos la reprografía y el tratamiento informático.

Astrophysical Journal, 2011

We report on the observation of γ-rays above 25 GeV from the Crab pulsar (PSR B0532+21) using the... more We report on the observation of γ-rays above 25 GeV from the Crab pulsar (PSR B0532+21) using the MAGIC I telescope. Two data sets from observations during the winter period 2007/2008 and 2008/2009 are used. In order to discuss the spectral shape from 100 MeV to 100 GeV, one year of public Fermi Large Area Telescope (Fermi-LAT) data are also analyzed to complement the MAGIC data. The extrapolation of the exponential cutoff spectrum determined with the Fermi-LAT data is inconsistent with MAGIC measurements, which requires a modification of the standard pulsar emission models. In the energy region between 25 and 100 GeV, the emission in the P1 phase (from -0.06 to 0.04, location of the main pulse) and the P2 phase (from 0.32 to 0.43, location of the interpulse) can be described by power laws with spectral indices of -3.1 ± 1.0stat ± 0.3syst and -3.5 ± 0.5stat ± 0.3syst, respectively. Assuming an asymmetric Lorentzian for the pulse shape, the peak positions of the main pulse and the interpulse are estimated to be at phases -0.009 ± 0.007 and 0.393 ± 0.009, while the full widths at half-maximum are 0.025 ± 0.008 and 0.053 ± 0.015, respectively.

Journal of Hypertension, 2006

Epidemiological data on the incidence and prevalence of cardiovascular disease in chronic renal f... more Epidemiological data on the incidence and prevalence of cardiovascular disease in chronic renal failure are scant The objective of the present study is to assess the relationship between renal function, measured by the estimated glomerular filtration rate, and the presence of early or established cardiovascular disease, in a population of hypertensives from primary care. Cross-sectional, multicentre study carried out in primary care centres all over Spain. Hypertensive subjects, older than 55 years, were included. In all of them a structured interview including cardiovascular risk factors or disease was performed. Blood pressure was measured following a standard procedure, and serum biochemistry and an electrocardiogram were obtained. Renal function was estimated using the abbreviated MDRD (Modification of Diet in Renal Disease Study Group) equation. For each glomerular filtration rate stratum the odds ratio and 95% confidence interval (CI) of left ventricular hypertrophy or cardiovascular disease were calculated, adjusted by confounding variables. A total of 13 687 patients (mean age 68.1 years, women 55.4%, diabetics 30.6%, body mass index 28.6 kg/m2) were included. Of these, 26.4% had established cardiovascular diseases and 20.3% electrocardiographic left ventricular hypertrophy. The average serum creatinine was 1.01 mg/dl, creatinine clearance 70.0 ml/min, and glomerular filtration rate 74.0 ml/min per 1.73 m2. Thirty-three patients (0.24%) had glomerular filtration rate < 5 ml/min per 1.73 m2; 89 (0.65%) from 15 to 29; 3745 (27.36%) from 30 to 59; 7798 (56.97%) from 60 to 89; and 2019 (14.75%) higher than 89 ml/min per 1.73 m2. In a multiple regression analysis, after adjusting by age, sex, body mass index, diabetes, systolic and diastolic blood pressure, and smoking, a lower glomerular filtration rate was associated with a higher prevalence of left ventricular hypertrophy. Likewise, a reduction in the glomerular filtration rate was also associated with a higher prevalence of cardiovascular disease. In hypertensive patients from primary care, the prevalence of cardiovascular disease is inversely proportional to the level of renal function. Estimated glomerular filtration is easy to determine and complements evaluation of the hypertensive patient.

Revista Espanola De Cardiologia, 2009

To determine the prevalence of a low high-density lipoprotein cholesterol (HDL-C) concentration i... more To determine the prevalence of a low high-density lipoprotein cholesterol (HDL-C) concentration in 11 042 hypertensive Spanish women aged ≥55 years, to identify factors associated with a low concentration, and to evaluate its relationship with cardiovascular disease (CVD).

Astroparticle Physics, 2009

The Cherenkov light flashes produced by Extensive Air Showers are very short in time. A high band... more The Cherenkov light flashes produced by Extensive Air Showers are very short in time. A high bandwidth and fast digitizing readout, therefore, can minimize the influence of the background from the light of the night sky, and improve the performance in Cherenkov telescopes. The time structure of the Cherenkov image can further be used in single-dish Cherenkov telescopes as an additional parameter to reduce the background from unwanted hadronic showers. A description of an analysis method which makes use of the time information and the subsequent improvement on the performance of the MAGIC telescope (especially after the upgrade with an ultra fast 2 GSamples/s digitization system in February 2007) will be presented. The use of timing information in the analysis of the new MAGIC data reduces the background by a factor two, which in turn results in an enhancement of about a factor 1.4 of the flux sensitivity to point-like sources, as tested on observations of the Crab Nebula.

Journal of Allergy and Clinical Immunology, 2004

Hereditary angioedema (HAE), a rare but life-threatening condition, manifests as acute attacks of... more Hereditary angioedema (HAE), a rare but life-threatening condition, manifests as acute attacks of facial, laryngeal, genital, or peripheral swelling or abdominal pain secondary to intra-abdominal edema. Resulting from mutations affecting C1 esterase inhibitor (C1-INH), inhibitor of the first complement system component, attacks are not histamine-mediated and do not respond to antihistamines or corticosteroids. Low awareness and resemblance to other disorders often delay diagnosis; despite availability of C1-INH replacement in some countries, no approved, safe acute attack therapy exists in the United States. The biennial C1 Esterase Inhibitor Deficiency Workshops resulted from a European initiative for better knowledge and treatment of HAE and related diseases. This supplement contains work presented at the third workshop and expanded content toward a definitive picture of angioedema in the absence of allergy. Most notably, it includes cumulative genetic investigations; multinational laboratory diagnosis recommendations; current pathogenesis hypotheses; suggested prophylaxis and acute attack treatment, including home treatment; future treatment options; and analysis of patient subpopulations, including pediatric patients and patients whose angioedema worsened during pregnancy or hormone administration. Causes and management of acquired angioedema and a new type of angioedema with normal C1-INH are also discussed. Collaborative patient and physician efforts, crucial in rare diseases, are emphasized. This supplement seeks to raise awareness and aid diagnosis of HAE, optimize treatment for all patients, and provide a platform for further research in this rare, partially understood disorder.

Revista Espanola De Cardiologia, 2006

trophy (LVH) is the earliest manifestation of cardiac damage in hypertension. Its appearance is a... more trophy (LVH) is the earliest manifestation of cardiac damage in hypertension. Its appearance is associated with a poor cardiovascular prognosis. The objectives of this study were to determine the prevalence of electrocardiographic LVH and to assess the epidemiological characteristics of hypertensive patients receiving primary care.

Astronomy & Astrophysics, 2011

Results. We find that the VHE gamma-ray emission detected in 2006 and 2007 challenges standard on... more Results. We find that the VHE gamma-ray emission detected in 2006 and 2007 challenges standard one-zone model, based on relativistic electrons in a jet scattering broad line region photons, while the other studied models fit the observed spectral energy distribution more satisfactorily.

Science, 2008

The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has det... more The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has detected very-high-energy gamma rays from a giant flare of the distant Quasi-Stellar Radio Source (in short: radio quasar) 3C 279, at a distance of more than 5 billion light-years (a redshift of 0.536). No quasar has been observed previously in very-high-energy gamma radiation, and this is also the most distant object detected emitting gamma rays above 50 gigaelectron volts. Since high-energy gamma rays may be stopped by interacting with the diffuse background light in the universe, the observations by MAGIC imply a low amount for such light, consistent with that known from galaxy counts.

Reservados todos los detechos. Quedan rigurosamente prohibidas, sin la autorización escrita de lo... more Reservados todos los detechos. Quedan rigurosamente prohibidas, sin la autorización escrita de los titulares del copyright, bajo las sanciones establecidas en las leyes, la reproducción total o parcial de esta obra por cualquier medio o procedimiento, comprendidos la reprografía y el tratamiento informático.