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Papers by Gregorio Herrera

Clinical & Translational Oncology, 2011

Background Astrocytomas of the spinal cord have rarely been reported. We examined our experience,... more Background Astrocytomas of the spinal cord have rarely been reported. We examined our experience, treatment and outcome of patients treated during the last four years. Material and methods We reviewed the charts from patients treated for this neoplasm in a multidisciplinary team of Granada, Spain. The information was retrospectively obtained from the patients’ hospital records. The patients were evaluated with clinical history, physical exam, spinal magnetic resonance (MR), surgery, location and histology, treatment, and follow-up. Results In the last four years, we have treated 37 astrocytomas, of which only 3 were intramedullary. All patients underwent surgery, radiotherapy and chemotherapy. Two patients died, but one is alive and practically asymtomatic. Conclusion The optimal treatment remains controversial. Radiotherapy should be considered for tumors with high-grade histopathology, clinically progressive and when a substantial resection cannot be achieved. New therapeutic strategies need to be studied to improve survival

Con frecuencia, la realización de auditorías a estados financieros, presenta variaciones en el ti... more Con frecuencia, la realización de auditorías a estados financieros, presenta variaciones en el tiempo de terminación. Es en este estudio, que la firma de Contadores Públicos “Martínez Rivera, SC, al igual que otros despachos, han venido observando este hecho, lo que conlleva ...

This paper presents evidence of an important decline during recent decades in the pass-through fr... more This paper presents evidence of an important decline during recent decades in the pass-through from the price of oil to the general price level. We find that this decline is a generalized fact for a large set of countries. After documenting correlations between the consumer price index and oil prices, we use two estimation strategies in an attempt to properly identify the effect of oil shocks on inflation. First, we estimate the traditional Phillips curve augmented to include oil and test for structural breaks in 34 countries. This methodology shows a fall in the average estimated pass-through for industrial economies and, to a lesser degree, for emerging economies. Second, we estimate rolling vector autoregressions for a subsample of countries for which we have sufficient data. We derive impulse response functions of inflation to oil shocks and interpret the integrals as estimates of pass-through. We find that the effect of oil shocks on inflation has weakened for most of the 12 countries in the sample. Among the factors that might help to explain this decline, we argue that the most important are a reduction in the oil intensity of economies around the world, a reduction in the exchange rate pass-through, a more favorable inflation environment, and the fact that the current oil price shock is largely the result of strong world demand. These factors help to explain not only why the current shock has had limited inflationary effects, but also why it has had limited consequences for output.

Journal of Vascular and Interventional Radiology, 2003

To report experience with the retrievable Günther Tulip filter (GTF) as a means of temporary cava... more To report experience with the retrievable Günther Tulip filter (GTF) as a means of temporary caval filtration for the prevention of pulmonary embolism (PE) with use of a technique that prolongs filter dwell time beyond 14 days. Eighty-eight GTFs were implanted in 87 patients. The GTFs were placed with the intention of retrieval in all patients within 14 days after initial implantation. In 23 of the 87 patients (26%), there was a need to prolong temporary caval filtration beyond the recommended period of 14 days. This was successfully achieved with use of percutaneous techniques from the right internal jugular vein whereby the filter was repositioned to a different location within the inferior vena cava (IVC) before definitive device removal. Of 88 GTFs implanted in 87 patients, 70 were successfully retrieved and 18 were left in place permanently. Forty-seven filters in 46 patients were removed after initial implantation with no need for percutaneous repositioning within the IVC to prolong dwell time (mean dwell time, 13 days). In the 23 patients who required repositioning of 23 GTFs within the IVC to prolong temporary caval filtration, the mean dwell time was 34.8 days; the mean number of repositioning procedures was 1.5, the mean time between repositioning procedures was 13.8 days, and the mean fluoroscopy time was 4.4 minutes in patients in whom filter retrieval was attempted. One patient underwent placement and subsequent removal of the GTF twice for perioperative prophylaxis against PE on two separate occasions. No filters were misplaced in an unintended location or tilted (>15 degrees ) in relation to the main caval axis after deployment. In one patient, a GTF became permanently fixed in the IVC 16 days after initial implantation and could not be removed percutaneously. Nine patients had mild or moderate-sized cervical hematomas. One patient had recurrent asymptomatic PE 2 months after filter insertion. Dwell times of 14 days can be achieved in most patients before device removal. Prolongation of the dwell time beyond 14 days can be safely and easily achieved by performing percutaneous repositioning of the device within the IVC via a jugular approach.

Resumen En este documento se presentan los resultados de un benchmarking entre diferentes empresa... more Resumen En este documento se presentan los resultados de un benchmarking entre diferentes empresas del sector de la confección en el que se busca evaluar el grado de implementación de la Manufactura Esbelta (Lean Manufacturing) en sus respectivos procesos productivos. Específicamente se trabaja con empresas que fabrican blue jeans, camisas tipo polo y camisetas t-shirts. En efecto, este sector industrial en la ciudad de Medellín está muy desarrollado y es uno de los más dinámicos de la industria, por lo tanto es de mucho interés su evaluación. Para el desarrollo del benchmarking se construyó un cuestionario y se aplicó en las diferentes empresas entrevistadas. El resultado más significativo que se halló es que la implementación de las técnicas de Manufactura Esbelta no se encuentra muy difundida entre las compañías del sector y solamente las que tienen trayectoria de trabajo como empresas exportadoras o licenciatarias de marcas internacionales son las más avanzadas en su aplicación y desarrollo.

Materials Science and Engineering B-advanced Functional Solid-state Materials, 2002

An alternative way to characterise composition modulation in InxGa1− xP ALMBE layers grown on GaA... more An alternative way to characterise composition modulation in InxGa1− xP ALMBE layers grown on GaAs (001) substrate at a temperature of 420° C by selective etching and photo etching is presented for the first time. AFM and TEM examinations revealed characteristic ...

Clinical & Translational Oncology, 2011

Background Astrocytomas of the spinal cord have rarely been reported. We examined our experience,... more Background Astrocytomas of the spinal cord have rarely been reported. We examined our experience, treatment and outcome of patients treated during the last four years. Material and methods We reviewed the charts from patients treated for this neoplasm in a multidisciplinary team of Granada, Spain. The information was retrospectively obtained from the patients’ hospital records. The patients were evaluated with clinical history, physical exam, spinal magnetic resonance (MR), surgery, location and histology, treatment, and follow-up. Results In the last four years, we have treated 37 astrocytomas, of which only 3 were intramedullary. All patients underwent surgery, radiotherapy and chemotherapy. Two patients died, but one is alive and practically asymtomatic. Conclusion The optimal treatment remains controversial. Radiotherapy should be considered for tumors with high-grade histopathology, clinically progressive and when a substantial resection cannot be achieved. New therapeutic strategies need to be studied to improve survival

Con frecuencia, la realización de auditorías a estados financieros, presenta variaciones en el ti... more Con frecuencia, la realización de auditorías a estados financieros, presenta variaciones en el tiempo de terminación. Es en este estudio, que la firma de Contadores Públicos “Martínez Rivera, SC, al igual que otros despachos, han venido observando este hecho, lo que conlleva ...

This paper presents evidence of an important decline during recent decades in the pass-through fr... more This paper presents evidence of an important decline during recent decades in the pass-through from the price of oil to the general price level. We find that this decline is a generalized fact for a large set of countries. After documenting correlations between the consumer price index and oil prices, we use two estimation strategies in an attempt to properly identify the effect of oil shocks on inflation. First, we estimate the traditional Phillips curve augmented to include oil and test for structural breaks in 34 countries. This methodology shows a fall in the average estimated pass-through for industrial economies and, to a lesser degree, for emerging economies. Second, we estimate rolling vector autoregressions for a subsample of countries for which we have sufficient data. We derive impulse response functions of inflation to oil shocks and interpret the integrals as estimates of pass-through. We find that the effect of oil shocks on inflation has weakened for most of the 12 countries in the sample. Among the factors that might help to explain this decline, we argue that the most important are a reduction in the oil intensity of economies around the world, a reduction in the exchange rate pass-through, a more favorable inflation environment, and the fact that the current oil price shock is largely the result of strong world demand. These factors help to explain not only why the current shock has had limited inflationary effects, but also why it has had limited consequences for output.

Journal of Vascular and Interventional Radiology, 2003

To report experience with the retrievable Günther Tulip filter (GTF) as a means of temporary cava... more To report experience with the retrievable Günther Tulip filter (GTF) as a means of temporary caval filtration for the prevention of pulmonary embolism (PE) with use of a technique that prolongs filter dwell time beyond 14 days. Eighty-eight GTFs were implanted in 87 patients. The GTFs were placed with the intention of retrieval in all patients within 14 days after initial implantation. In 23 of the 87 patients (26%), there was a need to prolong temporary caval filtration beyond the recommended period of 14 days. This was successfully achieved with use of percutaneous techniques from the right internal jugular vein whereby the filter was repositioned to a different location within the inferior vena cava (IVC) before definitive device removal. Of 88 GTFs implanted in 87 patients, 70 were successfully retrieved and 18 were left in place permanently. Forty-seven filters in 46 patients were removed after initial implantation with no need for percutaneous repositioning within the IVC to prolong dwell time (mean dwell time, 13 days). In the 23 patients who required repositioning of 23 GTFs within the IVC to prolong temporary caval filtration, the mean dwell time was 34.8 days; the mean number of repositioning procedures was 1.5, the mean time between repositioning procedures was 13.8 days, and the mean fluoroscopy time was 4.4 minutes in patients in whom filter retrieval was attempted. One patient underwent placement and subsequent removal of the GTF twice for perioperative prophylaxis against PE on two separate occasions. No filters were misplaced in an unintended location or tilted (>15 degrees ) in relation to the main caval axis after deployment. In one patient, a GTF became permanently fixed in the IVC 16 days after initial implantation and could not be removed percutaneously. Nine patients had mild or moderate-sized cervical hematomas. One patient had recurrent asymptomatic PE 2 months after filter insertion. Dwell times of 14 days can be achieved in most patients before device removal. Prolongation of the dwell time beyond 14 days can be safely and easily achieved by performing percutaneous repositioning of the device within the IVC via a jugular approach.

Resumen En este documento se presentan los resultados de un benchmarking entre diferentes empresa... more Resumen En este documento se presentan los resultados de un benchmarking entre diferentes empresas del sector de la confección en el que se busca evaluar el grado de implementación de la Manufactura Esbelta (Lean Manufacturing) en sus respectivos procesos productivos. Específicamente se trabaja con empresas que fabrican blue jeans, camisas tipo polo y camisetas t-shirts. En efecto, este sector industrial en la ciudad de Medellín está muy desarrollado y es uno de los más dinámicos de la industria, por lo tanto es de mucho interés su evaluación. Para el desarrollo del benchmarking se construyó un cuestionario y se aplicó en las diferentes empresas entrevistadas. El resultado más significativo que se halló es que la implementación de las técnicas de Manufactura Esbelta no se encuentra muy difundida entre las compañías del sector y solamente las que tienen trayectoria de trabajo como empresas exportadoras o licenciatarias de marcas internacionales son las más avanzadas en su aplicación y desarrollo.

Materials Science and Engineering B-advanced Functional Solid-state Materials, 2002

An alternative way to characterise composition modulation in InxGa1− xP ALMBE layers grown on GaA... more An alternative way to characterise composition modulation in InxGa1− xP ALMBE layers grown on GaAs (001) substrate at a temperature of 420° C by selective etching and photo etching is presented for the first time. AFM and TEM examinations revealed characteristic ...