Sergio Gutierrez - Academia.edu (original) (raw)

Vol 3 Iss 6 by Sergio Gutierrez

Acute respiratory distress syndrome (ARDS) is a common syndrome in intensive care units, proper d... more Acute respiratory distress syndrome (ARDS) is a common syndrome in intensive care units, proper diagnosis and understanding of pathophysiology with the corresponding management positively affect the outcomes of patients with ARDS. The pathophysiology of ARDS is complex and involves a series of multiple biomolecular agents. There are multiple definitions of ARDS, the last assigned being the Berlin definition. There are some unknown aspects regarding ARDS that will be recognized within a few years of research. The purpose of this review is refresh some aspects as pathophysiology and classification about ARDS.
Keywords: Respiratory Distress Syndrome; Adult; Pathophysiology; Definition; Treatment.

Papers by Sergio Gutierrez

Search all the public and authenticated articles in CiteULike. Include unauthenticated results to... more Search all the public and authenticated articles in CiteULike. Include unauthenticated results too (may include "spam") Enter a search phrase. You can also specify a CiteULike article id (123456),. a DOI (doi:10.1234/12345678). or a PubMed ID (pmid:12345678). Click Help for advanced usage. CiteULike, Group: MiGen Project, Search, Register, Log in, ...

Proceedings of the 2012 IEEE Global Engineering Education Conference (EDUCON), 2012

This article analyzes the use of wireless systems in learning environments and explains the advan... more This article analyzes the use of wireless systems in learning environments and explains the advantages of these when robots are used for educational purposes in recreational and industrial environments. This article reflects the importance that these tools may have in safety, efficiency and productivity of training in learning and e-learning as well as the motivation that this systems cause on

Lecture Notes in Computer Science, 2004

An adaptive tutoring system is presented based on hierarchical graphs that capture the sequencing... more An adaptive tutoring system is presented based on hierarchical graphs that capture the sequencing of a set of learning objects depending on how students interact with them. The use of hierarchy allows the definition of complex transition structures over arbitrarily large sets of objects. Using this approach a tutoring tool has been designed and tested in the context of an introductory course in Computer Architecture. Experimental results clearly show the positive impact of the proposed content adaptation over how students learn concepts.

Seventh IEEE International Conference on Advanced Learning Technologies (ICALT 2007), 2007

This paper describes a possible application of swarm intelligence techniques in e-learning: an au... more This paper describes a possible application of swarm intelligence techniques in e-learning: an auditing tool for pedagogical planning. Swarm intelligence techniques can be applied to a web system thanks to the fact that the available online material can be organized in a graph by means of hyperlinks. In this case, the swarm that moves on the graph is composed of

Clinical biomechanics (Bristol, Avon), 2014

Glenohumeral relationships in reverse shoulder arthroplasty patients have not been previously rep... more Glenohumeral relationships in reverse shoulder arthroplasty patients have not been previously reported. The purpose of this study was to quantify and compare the shoulder spatial relationships and moment arms. Measurements were used to define general size categories and determine if sizes scale linearly for all metrics. Ninety-two shoulders of patients undergoing primary reverse shoulder arthroplasty for functionally-deficient massive rotator cuff tear without bony deformity or deficiency were evaluated using three-dimensional CT reconstructions and computer-aided design software. Multiple glenohumeral relationships (including moment arm) were measured and evaluated for size stratification and linearity. Generalized linear modeling was used to investigate how predictive glenoid height, coronal humeral head diameter, and gender were of greater tuberosity positions. The 92 shoulders were grouped based on glenoid height: small (<33.4mm), medium (33.4-38.0mm), and large (>38.0mm)....

International Journal of Solids and Structures, 2007

For a long time it has been studied whether rank-one convexity and quasiconvexity give rise to di... more For a long time it has been studied whether rank-one convexity and quasiconvexity give rise to different families of constitutive relations in planar nonlinear elasticity. Stated in 1952 the Morrey conjecture says that these families are different, but no example has come forward to prove it. Now we attack this problem by deriving a specialized optimization algorithm based on two ingredients: first, a recently found necessary condition for the quasiconvexity of fourth-degree polynomials that distinguishes between both classes in the three dimensional case, and secondly, upon a characterization of rank-one convex fourth-degree polynomials in terms of infinitely many constraints.After extensive computational experiments with the algorithm, we believe that in the planar case, the necessary condition mentioned above is also necessary for the rank-one convexity of fourth-degree polynomials. Hence the question remains open.

Lecture Notes in Computer Science, 2008

We present a brief description of the design of a diagrambased system that supports the developme... more We present a brief description of the design of a diagrambased system that supports the development of thinking about mathematical generalisation. Within the software, the user constructs a dependency graph that explicitly shows the relationships between components of a task. Using this dependency graph, the user manipulates graphical visualisations of component attributes which helps them move from the specific case to the general rule. These visualisations provide the user with an intermediate representation of generality and facilitate movement between the specific details of the task, the appropriate generalisations, verbal descriptions of their understanding and various algebraic representations of the solutions.

Lecture Notes in Computer Science, 2008

Expressing generality, recognising and analysing patterns and articulating structure is a complex... more Expressing generality, recognising and analysing patterns and articulating structure is a complex task and one that is invariably problematic for students. Nonetheless, very few systems exist that support learners explicitly in the process of mathematical generalisation. We have addressed this by developing a novel environment that supports users in their reasoning and problem-solving of generalisation tasks. We have followed a stakeholder-centred design process, integrating feedback and reflections from twenty-four children, ...

2008 Eighth IEEE International Conference on Advanced Learning Technologies, 2008

Although the notion of generality is central in mathematics and science, being able to identify a... more Although the notion of generality is central in mathematics and science, being able to identify and express general patterns and/or articulating structures is one of the main difficulties for children when they learn mathematics. This paper presents a step towards a set of tools that addresses this problem problem by encouraging students to connect between actual activities within the task and expressions of generality. The paper describes a novel tool -ShapeBuilder -and how it can be used in the context of a well-known generalisation activity: tiling a pond. Insights gained from various small-scale studies with children are discussed followed by a description of how we expect this tool to develop in future work.

ZDM, 2009

Abstract In this paper, we seek to broaden the sense in which the word &amp;amp;amp;amp;a... more Abstract In this paper, we seek to broaden the sense in which the word &amp;amp;amp;amp;amp;amp;amp;#x27;dynamic&amp;amp;amp;amp;amp;amp;amp;#x27;is applied to computational media. Focussing exclusively on the problem of design, the paper describes work in progress, which aims to build a computational system that supports students&amp;amp;amp;amp;amp;amp;amp;#x27; engagement with mathematical generalisation in a collaborative classroom environment by helping them to begin to see its power and to express it for themselves and for others. We present students&amp;amp;amp;amp;amp;amp;amp;#x27; strengths and challenges in appreciating structure and expressing ...

The Spine Journal, 2011

PATIENT SAMPLE: 73 patients, age 46610 years, received 2 to 4-level fusion of L2-S1 vertebrae. Th... more PATIENT SAMPLE: 73 patients, age 46610 years, received 2 to 4-level fusion of L2-S1 vertebrae. Thrity-five patients received hardware removal 230630 days post-implantation. OUTCOME MEASURES: Outcome measures included: insertion torque, immediate removal torque, ultimate removal torque, evoked EMG stimulus threshold, screw size, and pedicle-screw clearance (pedicle thicknessscrew diameter). METHODS: Pedicle screw insertion (n5274) and removal (n5207) torques were measured using a manual torque wrench. Immediately upon insertion, pedicle screws were backed-out to assess immediate removal torque to ensure the insertion torque was not artificially elevated due to initial placement (n510). Paired samples (n526) were measured for both insertion and removal. EMG stimulation threshold currents for screw holes were measured prior to insertion and following removal. Paired and unpaired two-tailed t-tests were used to compare groups, as appropriate, with significance set at p!.05. Linear regressions were performed using Graph-Pad (Prism). All data reported as mean6SD. RESULTS: There were no differences between insertion and immediate removal torque (p5.56). However, upon ultimate removal, torque measure-

Journal of Shoulder and Elbow Surgery, 2011

Hypothesis/background: Patients who are treated with reverse shoulder arthroplasty in the setting... more Hypothesis/background: Patients who are treated with reverse shoulder arthroplasty in the setting of proximal humeral bone loss present a technical challenge for humeral component fixation. The purpose of this study was to determine the effect of proximal humeral bone loss on fixation of reverse shoulder humeral implants. Materials and methods: Three reverse humeral designs (two modular and one monobloc) were cemented into twenty-four Sawbones humeri prepared to simulate intact and proximal humeral bone loss. Torque was applied to the humerus for 1,000 cycles in increments of 2.5 N-m to 25 N-m. Rotational micromotion of the implant was measured. Results: There was a significant decrease in rotational micromotion in the intact constructs when compared with the bone loss constructs (we found P <.01 when looking at torsion levels of 5 to 17.5 N-m). In the intact humerus, 10 of 12 implant constructs survived testing. The 2 that failed were modular implants. In the bone loss setting, 7 of 12 implant constructs survived testing. The 5 that failed were also modular implants. Conclusions: This is the first investigation on humeral component fixation in reverse shoulder arthroplasty. The proximal humerus adds stability to the fixation of a cemented humeral implant. Modular components in the presence of proximal humeral bone loss may be at increased risk of mechanical failure. Conversely, non-modular cemented humeral components can withstand greater loads before failure. Level of evidence: Basic Science Study.

Journal of Shoulder and Elbow Surgery, 2007

There has been renewed interest in reverse shoulder arthroplasty for the treatment of glenohumera... more There has been renewed interest in reverse shoulder arthroplasty for the treatment of glenohumeral arthritis with concomitant rotator cuff deficiency. Failure of the prosthesis at the glenoid attachment site remains a concern. The purpose of this study was to examine glenoid component stability with regard to the angle of implantation. This investigation entailed a biomechanical analysis to evaluate forces and micromotion in glenoid components attached to 12 polyurethane blocks at Ϫ15°, 0°, and ϩ15°of superior and inferior tilt. The 15°inferior tilt had the most uniform compressive forces and the least amount of tensile forces and micromotion when compared with the 0°and 15°superiorly tilted baseplate. Our results suggest that implantation with an inferior tilt will reduce the incidence of mechanical failure of the glenoid component in a reverse shoulder prosthesis. (J Shoulder Elbow Surg 2007;16:9S-12S.) Rotator cuff deficiency with glenohumeral arthritis presents a unique challenge to the reconstructive surgeon. The complex motions of the shoulder joint require stability throughout an extended range of motion. When the rotator cuff is deficient or nonfunctional, total shoulder replacement has yielded poor results as a result of eccentric loading of the glenoid leading to loosening and early failure. 12 In the modern era, multiple procedures have been recommended to resolve this problem. These include semiconstrained 7,22,27 and constrained total shoulder arthroplasty, 4,26 shoulder arthrodesis, 6,20,31,35 and hemiarthroplasty. Hemiarthroplasty, the current standard of care for this condition, offers only limited goals for functional improvement 21 and only a modest improvement in pain. Recently, there has been renewed interest in semiconstrained reverse shoulder arthroplasty. Currently, however, there are minimal basic science data available on which to base rational clinical decisions. Several authors have reported promising results in the short and medium term using a reversed or inverted shoulder implant. The most recent study involving the Delta III prosthesis (DePuy Orthopaedics, Warsaw, IN) in the treatment of glenohumeral osteoarthritis with massive cuff rupture, a multicenter study of 80 shoulders in 77 patients, reported significant improvements in all 4 areas of the Constant score. However, 49 cases (63.6%) were noted to have medial component encroachment and scapular notching without evidence of loosening. The Reverse shoulder prosthesis (Encore Medical, Austin, TX) attempts to address the issue of scapular notching by providing the option for a more lateral center of rotation. However, this lateral placement yields a greater moment arm and hence generates greater torque at the glenoid baseplate-bone interface, creating concerns regarding early loosening and failure. In an effort to address this concern, the Reverse shoulder prosthesis uses enhanced baseplate fixation by use of a fixed-angle central screw with 4 peripheral locking screws. This configuration has demonstrated stability to cyclic loading equivalent to that of the Delta III design in the laboratory. To understand the mechanical factors involved in these early failures better, we examined the effect of baseplate orientation on the distribution of forces and micromotion at the bone-prosthesis interface. Three angles of implantation were examined: ϩ15°, 0°, and Ϫ15°of scapular plane tilt.

Journal of Shoulder and Elbow Surgery, 2008

The purpose of this study was to determine the effects of prosthetic design and surgical techniqu... more The purpose of this study was to determine the effects of prosthetic design and surgical technique of reverse shoulder implants on total abduction range of motion and impingement on the inferior scapular neck. Custom implants in three glenosphere diameters (30, 36, and 42 mm), with 3 different centers of rotation offsets (0, +5, and +10 mm), were placed into a Sawbones scapula (Pacific Research Laboratories, Vashon, WA) in 3 different positions: superior, center, and inferior glenoid. Humeral sockets were manufactured with a 130 , 150 , and 170 neck-shaft angle. Four independent factors (glenosphere diameter, center of rotation offset, glenosphere position on the glenoid, and humeral neckshaft angle) were compared with the 2 dependent factors of range of motion and inferior scapular impingement. Center of rotation offset had the largest effect on range of motion, followed by glenosphere position. Neck-shaft angle had the largest effect on inferior scapular impingement, followed by glenosphere position. This information may be useful to the surgeon when deciding on the appropriate reverse implant. (J Shoulder Elbow Surg 2008;17:608-615.) From the

Journal of Shoulder and Elbow Surgery, 2013

Modifications in reverse shoulder arthroplasty (RSA) have been made with the intent of maximizing... more Modifications in reverse shoulder arthroplasty (RSA) have been made with the intent of maximizing motion, although there is little objective evidence outlining their benefit. This study investigated the RSA component combinations that impart the greatest effect on impingement-free glenohumeral motion. A previously validated virtual shoulder model was implanted with RSA components that varied by humeral implant type (inset/onset), glenosphere diameter (30, 36, and 42 mm), glenosphere placement (inferior/neutral), glenosphere center-of-rotation offset (0, 5, and 10 mm), humeral neck-shaft angle (130° and 150°), and humeral offset (zero, five, and ten mm). Motion was simulated in all technique combinations until the point of impingement in abduction, flexion/extension (F/E), and internal/external rotation (IR/ER). Regression analysis was used to rank combinations based on motion. Of 216 possible study combinations, 126 constructs (58%) demonstrated no arm-at-side impingement and were included for analysis. Models with the largest motion in abduction, F/E, and IR/ER, respectively, were inset-42-inferior-10-150-zero (107°), inset-36-inferior-10-130-five (146°), and inset-42-inferior-10-130-ten (121°). Humeral neck-shaft angle, glenosphere center-of-rotation offset, glenosphere placement, and glenosphere diameter had a significant effect on motion in all planes tested. Of these variables, humeral neck-shaft angle was most predictive of a change in abduction and F/E motion, whereas glenosphere placement was most predictive of a change in IR/ER motion. Higher glenosphere center-of-rotation offsets led to an increase in motion in all planes. To maximize motion in abduction, a valgus humeral component should be selected; to maximize F/E, a varus humeral component should be selected; and, to maximize IR/ER, the glenosphere should be placed inferiorly.

The Journal of Bone and Joint Surgery (American), 2008

Evaluations of functional outcomes of reverse shoulder arthroplasty have revealed variable improv... more Evaluations of functional outcomes of reverse shoulder arthroplasty have revealed variable improvements in the range of motion and high rates of scapular notching. The purpose of this study was to systematically examine the impact of surgical factors (location of the glenosphere on the glenoid and tilt angle of the glenosphere on the glenoid) and implant-related factors (implant size, center-of-rotation offset, and humeral neck-shaft angle) on impingement-free abduction motion. A computer model was developed to virtually simulate abduction/adduction motion and its dependence on five surgical and implant-related factors. Three conditions were tested for each factor, resulting in a total of 243 simulated combinations. The overall motion was determined from 0 degrees of abduction until maximum abduction, which would be limited by impingement of the humerosocket on the scapula. In those combinations in which 0 degrees of abduction could not be achieved, the adduction deficit was recorded. The largest average increase in the range of impingement-free abduction motion resulted from a more lateral center-of-rotation offset: the average increase was 31.9 degrees with a change in the center-of-rotation offset from 0 to 10 mm, and this change resulted in an increase in abduction motion in eighty of the eighty-one combinations. The position of the glenosphere on the glenoid was associated with the second largest average increase in abduction motion (28.1 degrees when the glenosphere position was changed from superior to inferior, with the change resulting in an increase in seventy-one of the eighty-one combinations). These factors were followed by glenosphere tilt, humeral neck-shaft angle, and prosthetic size in terms of their effects on abduction motion. The largest effect in terms of avoiding an adduction deficit was provided by a humeral neck-shaft angle of 130 degrees (the deficit was avoided in forty-nine of the eighty-one combinations in which this angle was used), followed by an inferior glenosphere position on the glenoid (deficit avoided in forty-one combinations), a 10-mm lateral offset of the center of rotation, inferior tilt of the glenosphere, and a 42-mm-diameter prosthetic size. An understanding of a hierarchy of prosthetic design and implantation factors may be important to maximize impingement-free abduction motion as well as to avoid inferior impingement.

Proceedings of the 2012 IEEE Global Engineering Education Conference (EDUCON), 2012

Lecture Notes in Computer Science, 2004

Seventh IEEE International Conference on Advanced Learning Technologies (ICALT 2007), 2007

Clinical biomechanics (Bristol, Avon), 2014

International Journal of Solids and Structures, 2007

Lecture Notes in Computer Science, 2008

2008 Eighth IEEE International Conference on Advanced Learning Technologies, 2008

ZDM, 2009

The Spine Journal, 2011

Journal of Shoulder and Elbow Surgery, 2011

Journal of Shoulder and Elbow Surgery, 2007

Journal of Shoulder and Elbow Surgery, 2008

Journal of Shoulder and Elbow Surgery, 2013

The Journal of Bone and Joint Surgery (American), 2008

Inverse Problems in Science and Engineering, 2011

This article is devoted to the detection of inclusions using a single boundary measurement obtain... more This article is devoted to the detection of inclusions using a single boundary measurement obtained from quasi-static essays in linear elasticity. The idea is to minimize the misfit between the displacement field obtained on part of the boundary and the boundary data coming from solving the elasticity equations with a guess inclusion. The optimization algorithm comes from the work of Allaire and Gutiérrez [G. Allaire and S. Gutiérrez, Optimal design in small amplitude homogenization, Math. Model. Numer. Anal. 41(3) (2007), pp. 543–574] and it is based on the assumption that the contrast on the values of the Lamé elastic coefficients between the defect and the matrix is not very large. This approach is promising because it is well adapted to cases when the defect is caused, for example, by weak inhomogeneities during the fabrication process. From the numerical examples we conclude that the method is quite robust under noisy measurements and errors in the characterization of the defect.