Cabezas A.C.,South Colombian University |
Patron J.J.S.,South Colombian University
ARPN Journal of Engineering and Applied Sciences | Year: 2017
In this paper we study the main performance characteristics of SMAC, a media access control protocol for sensor networks (WSN). SMAC was designed keeping in mind the characteristics of energy scarcity and processing capacity of the sensor nodes and achieves reduction in energy consumption at the expense of other performance parameters such as delay, throughput and bandwidth usage. Our contributions through this work are: first, a model of physical layer corresponding to the transmitter/receiver CC2420 radio including a model of energy consumption and a model of the SMAC protocol based on the specifications of the authors implemented in Qualnet® and second, a detailed analysis of protocol performance based on different metrics. Through our study we provide to designers of sensor networks operating parameters and performance information. © 2006-2017 Asian Research Publishing Network (ARPN). All rights reserved.
Vinck-Posada H.,National University of Colombia |
Segovia-Chaves F.A.,National University of Colombia |
Segovia-Chaves F.A.,South Colombian University
Journal of Physics: Conference Series | Year: 2017
We have calculated the dependence of transmittance spectra with wavelength for TE wave at normal incidence in one-dimensional dielectric photonic crystals (1DPC) using the transfer matrix method. We demonstrate that when consider two defects layers spatial breaking periodicity in the 1DPC, the presence of defect modes located within the photonic band gap can be found. Additionally we have calculated the effect on the transmittance spectrum by varying the thickness of the defects in the 1DPC. © Published under licence by IOP Publishing Ltd.
Orduz L.H.,South Colombian University
ARPN Journal of Engineering and Applied Sciences | Year: 2017
Every hydrocarbon well uses tools and equipment not only for drilling but also for well completion, stimulation and production activities; all equipment is tested at conditions of pressure and surface temperature before being lowered into the well, during the run and during program operation, all the equipment is exposed to pressures and temperatures and changes by fluid movements generating variations that can affect their behavior. In this document the changes to which they are exposed in the well and a condensed during the run in hole and during operations, with calculating regarding the proposed service by the company and some authors regard. © 2006-2016 Asian Research Publishing Network (ARPN). All rights reserved.
Kovacs F.M.,Fundacion Kovacs |
Urrutia G.,Biomedical Research Institute Sant Pau |
Urrutia G.,CIBER ISCIII |
Urrutia G.,Autonomous University of Barcelona |
Alarcon J.D.,South Colombian University
Spine | Year: 2011
STUDY DESIGN.: Systematic review. OBJECTIVE.: To compare the effectiveness of surgery versus conservative treatment on pain, disability, and loss of quality of life caused by symptomatic lumbar spinal stenosis (LSS). SUMMARY OF BACKGROUND DATA.: LSS is the most common reason for spine surgery in persons older than 65 years in the United States. METHODS.: Randomized controlled trials (RCTs) comparing any form of conservative and surgical treatment were searched in CENTRAL, MEDLINE, EMBASE, and TripDatabase databases until July 2009, with no language restrictions. Additional data were requested from the authors of the original studies. The methodological quality of each study was assessed independently by two reviewers, following the criteria recommended by the Cochrane Back Review Group. Only data from randomized cohorts were extracted. RESULTS.: A total of 739 citations were reviewed. Eleven publications corresponding to five RCTs were included. All five scored as high quality despite concerns deriving from heterogeneity of treatment, lack of blinding, and potential differences in the size of the placebo effect across groups. They included a total of 918 patients in whom conservative treatments had failed for 3 to 6 months, and included orthosis, rehabilitation, physical therapy, exercise, heat and cold, transcutaneous electrical nerve stimulation, ultrasounds, analgesics, nonsteroidal anti-inflammatory drugs, and epidural steroids. Surgical treatments included the implantation of a specific type of interspinous device and decompressive surgery (with and without fusion, instrumented or not). In all the studies, surgery showed better results for pain, disability, and quality of life, although not for walking ability. Results of surgery were similar among patients with and without spondylolisthesis, and slightly better among those with neurogenic claudication than among those without it. The advantage of surgery was noticeable at 3 to 6 months and remained for up to 2 to 4 years, although at the end of that period differences tended to be smaller. CONCLUSION.: In patients with symptomatic LSS, the implantation of a specific type of device or decompressive surgery, with or without fusion, is more effective than continued conservative treatment when the latter has failed for 3 to 6 months. © 2011, Lippincott Williams &Wilkins.
Rodriguez-Calderon W.,University of la Salle of Colombia |
Pallares-Munoz M.R.,South Colombian University
DYNA (Colombia) | Year: 2015
The model developed tries to predict the stresses and strains of the structure of the pavement in a more real way, doing a lineal elastic structural analysis in three dimensions with capacity to model loads of double axes, that which constitutes an advance regarding twodimensional axisymmetrical models that only represent the state tense-deformational of the pavement under loads of simple axes. Earlier stages of this research showed two-dimensional models under different load scenarios, league between layers and nonlinear constitutive models, however the purpose is to move towards analysis methodology stress-strain state under standard loads. The model was implemented in the Algor© program and a comparison with the Elsym5 multilayer freeware was performed. The results warn the existence of shear stress concentrations that can be causing major flaws that are not considered in traditional design methods which could lead to the possibility of reassessed. © The author; licensee Universidad Nacional de Colombia.
Kesinger M.R.,University of Pittsburgh |
Puyana J.C.,University of Pittsburgh |
Rubiano A.M.,South Colombian University
World Journal of Surgery | Year: 2014
Background: Standardized trauma protocols (STPs) have reduced morbidity and mortality in mature trauma systems. Most hospitals in low- and middle-income countries (LMICs) have not yet implemented such protocols, often due to financial and logistic limitations. We report preliminary findings from a trauma quality improvement (QI) initiative, using and evaluating the impact of a low-cost STP in an LMIC university hospital. Methods: We developed an STP based on generally accepted best practices and damage control resuscitation. It was designed for the resources available at the test institution. The Neiva University Hospital (NUH) is a tertiary care hospital and level I trauma center in Neiva, Colombia. As in most LMIC hospitals, there was no trauma information data system at NUH. Therefore, we adapted an administrative electronic database to capture clinically relevant information of adult patients who were hospitalized or died in the emergency department (ED) between August 2010 and June 2012 with an International Classification of Diseases, 10th revision (ICD-10) diagnoses indicating trauma (S00-Y98). Interventions that were recommended in the STP were compared in these two groups. Length of hospital stay (LOS) and mortality were also examined. Results: A total of 4,324 patients were included, of whom, 2,457 patients were in the pre-protocol period and 1,867 were in the post-protocol period. The use of several interventions increased: blood product transfusions in the ED (1.0 vs. 2.7 %; p < 0.001), use of hypertonic fluids in hypotensive patients (3.2 vs. 8.9 %; p < 0.001), placement of Foley catheters (11.1 vs. 13.8 %; p = 0.007), arterial blood gas draws (16.6 vs. 26.4 %; p < 0.001), tetanus vaccinations (19.3 vs. 26.0 %; p < 0.001), placement of multiple large bore peripheral catheters (29.5 vs. 34.7 %; p < 0.001), prophylactic antibiotics (34.9 vs. 38.0 %; p = 0.035), and the use of analgesics (64.5 vs. 68.0 %; p = 0.016). Other interventions also trended upwards. Length of stay (LOS) decreased for both surgical and non-surgical patients (surgical 13.4 vs. 11.8 days; p = 0.017; non-surgical 4.4 vs. 3.8 days; p = 0.059). All-cause mortality of trauma patients decreased (3.9 vs. 2.9 %; p = 0.088). Conclusions: The institution of an STP at a university hospital in an LMIC has increased the use of vital interventions while decreasing overall LOS for all-cause trauma patients. © 2014 Société Internationale de Chirurgie.
Kesinger M.R.,University of Pittsburgh |
Nagy L.R.,University of Pittsburgh |
Sequeira D.J.,University of Pittsburgh |
Charry J.D.,South Colombian University |
And 2 more authors.
Injury | Year: 2014
Introduction Standardized trauma protocols (STP) have reduced morbidity and in-hospital mortality in mature trauma systems. Most hospitals in low- and middle-income countries (LMICs) have not implemented STPs, often because of financial and logistic limitations. We report the impact of an STP designed for the care of trauma patients in the emergency department (ED) at an LMIC hospital on patients with severe traumatic brain injury (STBI). Methods We developed an STP based on generally accepted best practices and damage control resuscitation for a level I trauma centre in Colombia. Without a pre-existing trauma registry, we adapted an administrative electronic database to capture clinical information of adult patients with TBI, a head abbreviated injury score (AIS) ≥3, and who presented ≤ 12 h from injury. Demographics, mechanisms of injury, and injury severity were compared. Primary outcome was in-hospital mortality. Secondary outcomes were Glasgow Coma Score (GCS), length of hospital and ICU stay, and prevalence of ED interventions recommended in the STP. Logistic regression was used to control for potential confounders. Results The pre-STP group was hospitalized between August 2010 and August 2011, the post-STP group between September 2011 and June 2012. There were 108 patients meeting inclusion criteria, 68 pre-STP implementation and 40 post-STP. The pre- and post-STP groups were similar in age (mean 37.1 vs. 38.6, p = 0.644), head AIS (median 4.5 vs. 4.0, p = 0.857), Injury Severity Scale (median 25 vs. 25, p = 0.757), and initial GCS (median 7 vs. 7, p = 0.384). Post-STP in-hospital mortality decreased (38% vs. 18%, p = 0.024), and discharge GCS increased (median 10 vs. 14, p = 0.034). After controlling for potential confounders, odds of in-hospital mortality post-STP compared to pre-STP were 0.248 (95%CI: 0.074-0.838, p = 0.025). Hospital and ICU stay did not significantly change. The use of many ED interventions increased post-STP, including bladder catheterization (49% vs. 73%, p = 0.015), hypertonic saline (38% vs. 63%, p = 0.014), arterial blood gas draws (25% vs. 43%, p = 0.059), and blood transfusions (3% vs. 18%, p = 0.008). Conclusions An STP in an LMIC decreased in-hospital mortality, increased discharge GCS, and increased use of vital ED interventions for patients with STBI. An STP in an LMIC can be implemented and measured without a pre-existing trauma registry. © 2014 Elsevier Ltd.
Di Donfrancesco B.,Kansas State University |
Gutierrez Guzman N.,South Colombian University |
Chambers E.,Kansas State University
Journal of Sensory Studies | Year: 2014
Sensory profiles of 13 coffee samples from the Huila Region, Colombia were evaluated using two different sensory panels: a highly trained descriptive sensory panel and a group of Q-certified coffee cuppers. The trained panel consisted of six descriptive panelists who developed a lexicon to evaluate and then test the coffee samples. Four "cuppers" scored the same samples based on the Specialty Coffee Association of America "cupping protocol." In addition, cuppers generated tasting notes to characterize the different coffee samples. Data indicated little overlap between the two methods and a low relationship between the two different sets of terms. Moreover, tasting notes by cuppers indicate lack of agreement on the terms used to describe samples, with only four terms used by more than two assessors to describe a single coffee product out of a total of 59 terms used by the cuppers. The results indicate that the cupping method and sensory descriptive methods provide different information that cannot be used as an alternative to each other when describing coffee products. Instead, the results suggest that the two types of data may be used synergistically to evaluate the quality and the sensory properties to better characterize coffee samples. Practical Applications: This research shows that "expert" coffee cupper data and trained sensory panel data cannot be used interchangeably. Thus, for research purposes sensory panel information is necessary for tracking changes in sensory properties. © 2014 Wiley Periodicals, Inc.
Escobar F.H.,South Colombian University |
Montenegro L.M.,South Colombian University |
Bernal K.M.,South Colombian University
ARPN Journal of Engineering and Applied Sciences | Year: 2014
Currently, the oil industry is focused on the exploitation of unconventional reservoirs. Wells in such unconventional resources as gas shale formations have to be hydraulically fractured for commercial production since the permeability is very low to ultralow reaching values in the order of nanodarcies. Also, gas shale wells are normally tested by recording the flow rate versus time readings under constant pressure conditions so an analysis of the reciprocal rate and reciprocal rate derivative following the TDS philosophy is presented for two cases in which the network of microfractures around the main fracture system provides an improvement of the permeability in such zone and one case in which the permeability is considered to be uniform. These three cases have been dealt in the literature with decline-curve analysis and the identification of the permeability model, dealt as a transition period, is conducted by type-curve matching which basically consists of a trial-and-error procedure. Here, we found that the application of the reciprocal rate derivative allows to easily identify the type of permeability model to be used: uniform, linear and exponential since the before-called transition period is shown on the derivative curve as a specific behavior which has been arbitrarily called "multilinear flow regime" displaying a slope of either 0.66 or 0.61 on the reciprocal rate derivative curve for the exponential and linear variation models, respectively. The extension of the TDS technique allows for the characterization of well test data so permeability, fracture length, skin factor and reservoir length are estimated and successfully verified by their application to synthetic and field examples. © 2006-2014 Asian Research Publishing Network (ARPN).
Salgado D.,South Colombian University |
Zabaleta T.E.,South Colombian University |
Hatch S.,University of Massachusetts Medical School |
Vega M.R.,South Colombian University |
Rodriguez J.,South Colombian University
Pediatric Infectious Disease Journal | Year: 2012
The current treatment for dengue hemorrhagic fever largely consists of supportive care. The drug pentoxifylline has been shown to blunt the proinflammatory actions of tumor necrosis factor-α, a key mediator of dengue hemorrhagic fever. We performed a pilot study evaluating pentoxifylline's effect on 55 children with dengue hemorrhagic fever. We believe our findings support the existing literature on its potential use in severe infection. © 2012 by Lippincott Williams ∧ Wilkins.