Search

We report severe acute respiratory syndrome coronavirus 2 antibody positivity among market and city bus depot workers in Lima, Peru. Among 1285 vendors from 8 markets, prevalence ranged from 27% to 73%. Among 488 workers from 3 city bus depots, prevalence ranged from 11% to 47%. Self-reported symptoms were infrequent. National Institute of Allergy and Infectious Diseases Revisión por pares

[EN] In this work we introduce new rational-polynomial Hermite matrix expansions which allow us to obtain a new accurate and efficient method for computing the matrix cosine. This method is compared with other state-of-the-art methods for computing the matrix cosine, including a method based on Pade approximants, showing a far superior efficiency, and higher accuracy. The algorithm implemented on the basis of this method can also be executed either in one or two NVIDIA GPUs, which demonstrates its great computational capacity. (C) 2018 Elsevier B.V. All rights reserved., This work has been partially supported by Spanish Ministerio de Economia y Competitividad and European Regional Development Fund (ERDF) grants TIN2014-59294-P, and T1N2017-89314-P.

[EN] We present in this paper a new method based on Bernoulli matrix polynomials to approximate the exponential of a matrix. The developed method has given rise to two new algorithms whose efficiency and precision are compared to the most efficient implementations that currently exist. For that, a state-of-the-art test matrix battery, that allows deeply exploring the highlights and downsides of each method, has been used. Since the new algorithms proposed here do make an intensive use of matrix products, we also provide a GPUs-based implementation that allows to achieve a high performance thanks to the optimal implementation of matrix multiplication available on these devices. (c) 2020 Elsevier B.V. All rights reserved, This work has been partially supported by Spanish Ministerio de Economia y Competitividad and European Regional Development Fund (ERDF) grants TIN2017-89314-P and by the Programa de Apoyo a la Investigacion y Desarrollo 2018 of the Universitat Politecnica de Valencia (PAID-06-18) grants SP20180016.

Communication tools (advertising, social media, etc.) are evolving to become increasingly more visual, driven largely by the commercial preferences of younger generations (e.g., millennials), creating promising opportunities in many areas, including research. Visuals provide an opportunity to make questionnaires and scales that are more engaging and in sync with the times. The challenge when adding visuals to questions includes choosing the best type of visual and the possibility that the changes alter the questions. Even those that are strictly visual can compromise the validity of questionnaires or scales. Visuals that include pictorial descriptions with text have been shown to be helpful and to maintain validity among those confronting communication disparities; although, studies have not specifically analized these issues among educated younger generations. The objective of this study was to analize, among college students, a pictorial and non–pictorial scale with the intent to compare psychometric properties and to study users’ preferences between the two scales. The two scale versions (pictorial vs. non pictorial) demonstrated comparable test-retest reliability and internal consistency, and performed in theoretically predicted ways. College students preferred the pictorial format versus the original text-only version and considered the pictorial format to be friendlier, clearer, and faster to complete. Pictorial descriptions added to questions might offer advantages versus other type of visuals because pictorial descriptions have been consistently shown to have a minimal effect on the psychometrics of scales, both in previous studies and in the present study. With the evolving progress of visual preferences for communication tools, using this strategy in questionnaires, surveys, and scales can offer a more up-to-date appearance to engage younger generations and possibly encourage participation in research studies. Resumen Las herramientas de comunicacion (publicidad, medios sociales, etc.) han evolucionado hacia una comunicacion visual debido en gran parte a la preferencia comercial de generaciones mas jovenes, brindando oportunidades muy prometedoras en diferentes campos incluyendo la investigacion. Imagenes visuales proporcionan una oportunidad de hacer cuestionarios y escalas mas atractivas y acordes con los tiempos. El reto al agregar imagenes a las preguntas incluye encontrar aquellas imagenes que son las mas apropiadas, considerando que esos cambios pueden alterar a las preguntas. Imagenes que incluyen pictogramas con texto han mostrado mantener su validez al ser usadas por aquellos que afrontan disparidades en la comunicacion; pero no se han estudiado entre generaciones de jovenes con un nivel educativo mayor. El objetivo del estudio es analizar las propiedades psicometricas de una escala con y sin pictogramas al ser respondida por estudiantes universitarios y estudiar sus preferencias. Las dos versiones mostraron resultados comparables en la prueba de confiabilidad (test-re-test), consistencia interna, con un comportamiento predictivo como se predice en la teoria. Los estudiantes universitarios prefirieron el formato con pictogramas considerandolo amigable, mas claro y facil de completar. Los cuestionarios o escalas utilizando pictogramas, han mostrado ventajas al compararlos con aquellos que usan otro tipo de imagenes, pues de forma consistente muestran un minimo efecto en la consistencia de las escalas de acuerdo a previos estudios y en el presente. Dado el progreso en las preferencias en las herramientas de comunicacion, usando esta estrategia en cuestionarios, encuestas y escalas puede ofrecer una apariencia mas acorde con la epoca y atraer a generaciones de jovenes con la posibilidad de promover la participacion en estudios.

[EN] The computation of matrix trigonometric functions has received remarkable attention in the last decades due to its usefulness in the solution of systems of second order linear differential equations. Several state-of-the-art algorithms have been provided recently for computing these matrix functions. In this work, we present two efficient algorithms based on Taylor series with forward and backward error analysis for computing the matrix cosine. A MATLAB implementation of the algorithms is compared to state-of-the-art algorithms, with excellent performance in both accuracy and cost., This work has been supported by Spanish Ministerio de Economia y Competitividad and the European Regional Development Fund (ERDF) grant TIN2014-59294-P.

Tuberculosis (TB) an infectious disease and remains a major cause of death globally. The World Health Organization (WHO) estimates that there were 10.4 million new TB cases worldwide in 2015. The majority of the infected populations come from resource-poor and marginalized communities with poor healthcare infrastructure. It is critical to reduce TB diagnosis delay in mitigating disease transmission and minimizing the reproductive rate of the tuberculosis epidemic. To combine machine learning and mobile computing techniques may help to accelerate the TB diagnosis among these communities. The goal of our research is to reduce TB patient wait times for being diagnosed by developing new machine learning techniques and mobile health technologies. In this paper, major technique barriers and proposed system architecture are first introduced. Then two major progresses are reported: (1) To develop an X-ray image database and annotation software dedicated for automated TB screening. The annotation software can help to highlight the TB manifestations, which are very useful for machine learning algorithms; (2) To develop effective and efficient computational models to classify the image into different category of TB manifestations. The model we proposed is a deep convolutional neural networks (CNN)-based models. We have conducted substantial experiments and the results have demonstrated that our approach is promising. We envision our future work includes two research activities. First, we plan to improve the performance of the algorithms with deeper neural networks. Second, we plan to implement our algorithms on mobile device and deploy our system in the city of Carabayllo, a high-burden TB area in Lima, the capital of Peru.

[EN] In this work we introduce a new method to compute the matrix cosine. It is based on recent new matrix polynomial evaluation methods for the Taylor approximation and a mixed forward and backward error analysis. The matrix polynomial evaluation methods allow to evaluate the Taylor polynomial approximation of the matrix cosine function more efficiently than using Paterson-Stockmeyer method. A sequential Matlab implementation of the new algorithm is provided, giving better efficiency and accuracy than state-of-the-art algorithms. Moreover, we provide an implementation in Matlab that can use NVIDIA CPUs easily and efficiently. (C) 2018 Elsevier B.V. All rights reserved., This work has been partially supported by Spanish Ministerio de Economía y Competitividad and European Regional Development Fund (ERDF) grants TIN2014-59294-P, and TIN2017-89314-P.

[EN] This paper presents an implementation of one of the most up-to-day algorithms proposed to compute the matrix trigonometric functions sine and cosine. The method used is based on Taylor series approximations which intensively uses matrix multiplications. To accelerate matrix products, our application can use from one to four NVIDIA GPUs by using the NVIDIA cublas and cublasXt libraries. The application, implemented in C++, can be used from the Matlab command line thanks to the mex files provided. We experimentally assess our implementation in modern and very high-performance NVIDIA GPUs., This work has been supported by Spanish Ministerio de Economia y Competitividad and the European Regional Development Fund (ERDF) Grants TIN2014-59294-P and TEC2015-67387-C4-1-R

Introduction. The high prevalence of obesity among children of Mexican descent, living in either Mexico or the United States (US), might indicate they are at a higher risk when compared to other groups. Previous mental health studies have had conflicting outcomes, which may be the result of considering these children as a homogeneous group (by race or ethnicity) instead of considering intra-racial group disparities (e.g. socio-economic status, adversities). Objective: To compare the psychosocial profile by weight category (normal weight, overweight, or obese) of impoverished Mexican descendent children in a clinical setting. Objective. To compare the psychosocial profile by weight category (normal weight, overweight, or obese) of impoverished Mexican descendent children in a clinical setting. Method. The study design was cross sectional. Information was retrieved from medical records (N = 2237) that were obtained from five university-based clinics in a large metropolitan area on the US-Mexico border from May 2009 to August 2010. Results. Psychosocial and behavioral problems were present among this intra-racial group of Mexican-American children, with higher scores in the overweight and obese children than in the normal-weight children. Discussion and conclusion. Intra-racial differences among obese and overweight children could account for variation in results regarding the mental health of Mexican American children. Considering intra-racial group disparities when providing healthcare may improve delivery and promote better mental and health outcomes because some groups may need more attention than others. In addition, considering these groups when designing studies, may improve the accuracy and precision of study result interpretations.

Purpose: YouTube can be a valuable platform to provide preventative health education among children. During production of educational material, it is important to seriously consider that the competition for views on …

[EN] In this work an accurate and efficient method based on matrix splines for computing matrix exponential is given. An algorithm and a MATLAB implementation have been developed and compared with the state-of-the-art algorithms for computing the matrix exponential. We also developed a parallel implementation for large scale problems. This implementation allowed us to get a much better performance when working with this kind of problems., This work has been supported by Spanish Ministerio de Economia y Competitividad and the European Regional Development Fund (ERDF) grant TIN2014-59294-P.

Background. Collective violence attributed to organized crime has shown to be responsible for a considerable burden of physical and mental health morbidity among youth. Objective. To compare the emotional and behavioral problems of children exposed to early childhood poverty and/or collective violence in communities at the Mexico-United States border to children exposed to other social and health risks. Method. A cross-sectional study was carried out with individuals living in poverty at two sites at the Mexico-United States border. Individuals who responded once to the Pictorial Child Behavior Checklist (P+CBCL) in Spanish were selected randomly from clinics in a metropolitan area of El Paso, Texas, United States (poverty alone group), and Ciudad Juarez, Chihuahua, Mexico (poverty plus collective violence group). In addition, emotional and behavioral problems present in these groups were compared with available published emotional and behavioral CBCL scales of children exposed to other social and health risks. Results. Children exposed to both poverty and collective violence had higher emotional and behavioral problem scores as measured by the P+CBCL than those exposed to poverty alone. In addition, compared with children who were brain-injured, hearing impaired, or whose parents were exposed to drugs or alcohol, the poverty and collective violence group had higher levels of emotional and behavioral problems. Discussion and Conclusion. Systematic detection and treatment of children as young as 18 months exposed to trauma are necessary to diminish the mental health problems caused by the collective violence attributed to organized crime.

In Low and Middle-Income Countries (LMICs), efforts to eliminate the Tuberculosis (TB) epidemic are challenged by the persistent social inequalities in health, the limited number of local healthcare professionals, and the weak healthcare infrastructure found in resource-poor settings. The modern development of computer techniques has accelerated the TB diagnosis process. In this paper, we propose a novel method using Convolutional Neural Network(CNN) to deal with unbalanced, less-category X-ray images. Our method improves the accuracy for classifying multiple TB manifestations by a large margin. We explore the effectiveness and efficiency of shuffle sampling with cross-validation in training the network and find its outstanding effect in medical images classification. We achieve an 85.68% classification accuracy in a large TB image dataset, surpassing any state-of-art classification accuracy in this area. Our methods and results show a promising path for more accurate and faster TB diagnosis in LMICs healthcare facilities.

Patient misunderstandings of healthcare-related instructions result in significant health, social and economic consequences. Pushing the boundaries of traditional academic methods may offer strategies that promote new ways to improve communication and understanding between healthcare providers, caregivers and patients. Comics can be an educational tool, offering an innovative strategy to communicate health-related information. Our study objective was to compare parents' understanding of health-related instructions (i.e. prescription labels, medical instructions and emergency situation scenarios) that were presented using two different formats-sequential pictorial instructions (SPIs) versus written text instructions (WRIs).This was a cross-sectional study to compare parents' understanding of health-related instructions for pediatric patients using structured SPIs versus WRIs. Parents (n = 359, 18-82 years old) of pediatric patients were given a card with instructions that were presented as SPIs (n = 195, 54.3%) or WRIs (n = 164, 45.7%), and then they completed a questionnaire. Total (14 questions) and grouped scores (10 questions) for parental comprehension of prescription and medical emergency instructions were significantly higher among participants viewing the SPIs than those viewing the WRIs in both English and Spanish. The mean understanding of instructions significantly increased from 6% to 12.2% when comparing the WRI versus the SPI.Our initial findings indicate that parents and caregivers of pediatric patients had significantly better understanding and recall of instructions delivered using SPIs than using WRIs.

[EN] Trigonometric matrix functions play a fundamental role in second order differential equations. This work presents an algorithm based on Taylor series for computing the matrix cosine. It uses a backward error analysis with improved bounds. Numerical experiments show that MATLAB implementations of this algorithm has higher accuracy than other MATLAB implementations of the state of the art in the majority of tests. Furthermore, we have implemented the designed algorithm in language C for general purpose processors, and in CUDA for one and two NVIDIA GPUs. We obtained a very good performance from these implementations thanks to the high computational power of these hardware accelerators and our effort driven to avoid as much communications as possible. All the implemented programs are accessible through the MATLAB environment. (C) 2016 Elsevier B.V. All rights reserved., This work has been supported by Spanish Ministerio de Economía y Competitividad and European Regional Development Fund (ERDF) grant TIN2014-59294-P

As international guidelines increase access to antiretroviral therapy (ART) globally, ART adherence becomes increasingly important to achieve HIV treatment as prevention (TasP) goals. In the concentrated HIV epidemic among men who have sex with men (MSM) and transgendered women (TGW) in Lima, Peru, the independent correlates of ART nonadherence were examined to inform treatment intervention priorities. Cross sectional survey of HIV-infected MSM and TGW who are engaged in clinical care in Lima, Peru. From June to August 2012, 302 HIV-infected Peruvian MSM/TGW from three clinical care sites were recruited using convenience sampling to participate in a cross-sectional computer-assisted adherence survey. Several standardized screening measures associated with ART nonadherence were examined in order to determine the independent correlates of optimal (≥90%) and perfect (100%) adherence, which were assessed using logistic regression. Of the 302 participants recruited, 263 (87.1%) were prescribed ART. Among those prescribed ART, 229 (87.1%) reported optimal and 146 (55.5%) reported perfect adherence. The prevalence of alcohol use disorders (AUD; 43.2%), alcohol dependence (5.3%), recent drug use (6.0%), and depression (44.5%) was high, and most participants had some evidence of neurocognitive impairment. Meeting criteria for having an AUD and depression were collinear (p0.001). On multivariate analysis, having an AUD was inversely related and the only independent correlate of optimal (AOR = 0.427; 95% CI = 0.187-0.976) and perfect (AOR = 0.552; 95% CI = 0.327-0.930) ART adherence. AUDs are highly prevalent among Peruvian HIV-infected MSM and contribute significantly to ART nonadherence. These findings support the need for screening and treating underlying AUDs. In order to meet HIV TasP goals, evidence-based strategies targeting AUDs are likely to directly improve ART adherence and indirectly improve overall individual health, HIV treatment engagement, and reduce transmission to sexual partners among this vulnerable and disproportionally affected population.

The effects of video games on youths have been subject to debate. Some researchers have linked video games to behavioral and emotional problems, while others have found no adverse effects. The behavioral and emotional problems experienced by some gamers may be linked to certain types of video games. We hypothesized that Mexican American youths with lower socioeconomic status and who play “aggressive” video games have more emotional and behavioral problems than those who do not play such games. We examined a total of 579 youths using the Child Behavior Checklist and analyzing the games played within the last 6 months. Youths who played aggressive video games had higher scores and more emotional and behavioral problems compared with those who did not play aggressive video games.

Advances in technology have made ultrasonography a rapidly evolving concept in the practice of medicine and a valuable component of the competency-based education. American Medical Association (AMA) recently affirms that ‘ultrasound imaging is a safe, effective and efficient tool when utilized by, or under the direction of appropriately trained physicians.’ AMA also supports the educational efforts and widespread integration of ultrasound throughout the continuum of medical education. Training in ultrasonography is rapidly expanding to numerous residency programs of graduate medical education but discrepancies in ultrasound curriculum and criteria for proficiency exist among programs within the same discipline, despite clearly defined objectives recommended by the governing bodies. There is a trend to integrate ultrasonography into the curriculum of undergraduate medical education. However, funding, availability of ultrasound-trained faculty and student time are barriers to the implementation. Ultrasonography is a natural fit for competency-based training and should be introduced early in medical education. We expect that the LCME will soon mandate the integration of ultrasound into the 4-year curriculum. The imminent question that medical educators ask is not when ultrasound will become a required component of the curriculum but how to effectively integrate the teaching and training of ultrasound into the continuum of medical education. How to cite this article Baatar D, Peinado J, Sarmiento J, Ho H. Development of a Competency-based Training in Obstetrics and Gynecology Ultrasound for Undergraduate and Graduate Medical Education. Donald School J Ultrasound Obstet Gynecol 2014;8(1):83-86.

Differential matrix Riccati equations (DMREs) enable to model many physical systems appearing in different branches of science, in some cases, involving very large problem sizes. In this paper, we propose an adaptive algorithm for time-invariant DMREs that uses a piecewise-linearized approach based on the Pade approximation of the matrix exponential. The algorithm designed is based upon intensive use of matrix products and linear system solutions so we can seize the large computational capability that modern graphics processing units (GPUs) have on these types of operations using CUBLAS and CULATOOLS libraries (general purpose GPU), which are efficient implementations of BLAS and LAPACK libraries, respectively, for NVIDIA $$\copyright $$ © GPUs. A thorough analysis showed that some parts of the algorithm proposed can be carried out in parallel, thus allowing to leverage the two GPUs available in many current compute nodes. Besides, our algorithm can be used by any interested researcher through a friendly MATLAB $$\copyright $$ © interface.

This study compared the correlates of HIV risk among men who have sex with men (MSM) with newly diagnosed versus previously known HIV infection among 5,148 MSM recruited using modified snowball sampling in 5 Peruvian cities. Participants, if age ≥18 years and reporting sex with a male in the previous 12 months, underwent standardized computer-assisted risk assessments and HIV and syphilis testing. Overall, 420 (8.2 %) participants tested HIV seropositive, most of whom (89.8 %) were unaware of their HIV status. Compared to those who knew themselves to be HIV-infected, multivariate logistic regression demonstrated that unprotected anal intercourse at last encounter [AOR = 2.84 (95 % CI 1.09-7.40)] and having an alcohol use disorder (AUD) [AOR = 2.14 (95 % CI 1.01-5.54)] were independently associated with a newly diagnosed HIV infection. Being unaware of being HIV-infected was associated with high-risk sexual behaviors and AUDs, both of which are amenable to behavioral and medication-assisted therapy interventions.

Viewing extreme violence and terrorism, either directly by witnessing acts or indirectly by watching them in the media, affects children’s mental and emotional health (1), and some children are at a higher risk for negative effects than others. Indirect exposure to terrorism acts and threats through the media affects the mental health of children, in both short- and long-term ways that differ completely from the effects in adults. Children’s vulnerability, immaturity, and developmental state change their perspective, and the tools used to confront these issues do not affect each child equally. Additionally, emotional problems might not surface immediately; instead, they can remain latent until they surface eventually. How and when this occurs depends mostly on additive effects generated by the environment in which the child develops and additional disparities in which the child confronts. The Federal Bureau of Investigation (FBI) defines terrorism as “the unlawful use of force or violence against persons or property to intimidate or coerce a government, the civilian population, or any segment thereof, in furtherance of political or social objectives” (2). Direct or indirect exposure to terrorism violence provokes a state of terror in the general public through the use of calculated acts of violence, which includes murder, mutilation, and explosions that affect innocent people, often including children. Even though the events might no longer be in the news, the psychological scars and trauma caused by viewing the horrifying images and by the memories are pervasive and do not heal easily (3). The natural tendency of adults to try to forget about the problems and move on with their lives often results in underestimating the importance and effect of the exposure on the emotional and psychosocial problems of children. The negative effect of exposure to violence in the media on children has been extensively discussed for years, with many controversial and conflicting results and conclusions. While some have found highly negative effects (4–6), others have denied any possible effects from media exposure (7, 8). Nevertheless, the existing evidence about the effects of media exposure to terrorism and violence acts among children should not be underestimated or dismissed. The point of discussion here is to consider the need to support strategies that reduce the effects of unsupervised viewing of terrorism acts and threats presented by the media. While stopping the media presentation of this violence might not be possible, there is much room to consider strategies that can reduce and help to better understand the effects of violence on the emotional health of children at home, in school, and in health sector. The media itself can also help by increasing the attention given to these strategies.

In this paper a method for computing hyperbolic matrix functions based on Hermite matrix polynomial expansions is outlined. Hermite series truncation together with Paterson-Stockmeyer method allow to compute the hyperbolic matrix cosine efficiently. A theoretical estimate for the optimal value of its parameters is obtained. An efficient and highly-accurate Hermite algorithm and a MATLAB implementation have been developed. The MATLAB implementation has been compared with the MATLAB function funm on matrices of different dimensions, obtaining lower execution time and higher accuracy in most cases. To do this we used an NVIDIA Tesla K20 GPGPU card, the CUDA environment and MATLAB. With this implementation we get much better performance for large scale problems. (C) 2015 Elsevier Inc. All rights reserved., This work has been supported by Spanish Ministerio de Educacion TIN2014-59294-P.

In this work, we developed a parallel algorithm to speed up the resolution of differential matrix Riccati equations using a backward differentiation formula algorithm based on a fixed-point method. The role and use of differential matrix Riccati equations is especially important in several applications such as optimal control, filtering, and estimation. In some cases, the problem could be large, and it is interesting to speed it up as much as possible. Recently, modern graphic processing units (GPUs) have been used as a way to improve performance. In this paper, we used an approach based on general-purpose computing on graphics processing units. We used NVIDIA © GPUs with unified architecture. To do this, a special version of basic linear algebra subprograms for GPUs, called CUBLAS, and a package (three different packages were studied) to solve linear systems using GPUs have been used. Moreover, we developed a MATLAB © toolkit to use our implementation from MATLAB in such a way that if the user has a graphic card, the performance of the implementation is improved. If the user does not have such a card, the algorithm can also be run using the machine CPU. Experimental results on a NVIDIA Quadro FX 5800 are shown. Copyright © 2011 John Wiley & Sons, Ltd.

We assessed the potential impact of Internet partner notification among men who have sex with men and transgender women in Peru recently diagnosed as having sexually transmitted disease. Use of Internet partner notification was anticipated for 55.9% of recent partners, including 43.0% of partners not currently expected to be notified, a 20.6% increase in anticipated notification outcomes. © 2013 American Sexually Transmitted Diseases Association.

Differential Riccati equations play a fundamental role in control theory, for example, optimal control, filtering and estimation, decoupling and order reduction, etc. In this paper several algorithms for solving differential Riccati equations based on Adams–Bashforth and Adams–Moulton methods are described. The Adams–Bashforth methods allow us explicitly to compute the approximate solution at an instant time from the solutions in previous instants. In each step of Adams–Moulton methods an algebraic matrix Riccati equation (AMRE) is obtained, which is solved by means of Newton’s method. Nine algorithms are considered for solving the AMRE: a Sylvester algorithm, an iterative generalized minimum residual (GMRES) algorithm, a fixed-point algorithm and six combined algorithms. Since the above algorithms have a similar structure, it is possible to design a general and efficient algorithm that uses one algorithm or another depending on the considered differential matrix Riccati equation. MATLAB versions of the above algorithms are developed, comparing precision and computational costs, after numerous tests on five case studies. © 2010 Elsevier Ltd. All rights reserved.

High adherence and maintenance of blinding are critical for placebo-controlled efficacy trials of HIV-1 biomedical prevention strategies. We assessed adherence to study drug and factors affecting adherence, including perceived randomization group, in a post-trial questionnaire of participants who completed HPTN 039, a randomized, placebo-controlled trial of HSV-2 suppression with twice-daily acyclovir to reduce HIV-1 acquisition. Of the 3172 trial participants, 2003 (63%) completed the post-trial questionnaire. Of these 2003, 72% reported missing a dose of study drug less than twice a week. Study drug adherence was not compromised by perceived randomization or genital ulcer symptoms during the study. Alcohol use was cited as an adherence barrier in some populations. Assessment of study drug adherence during and at the end of trials can evaluate perceptions of randomization and adherence by randomization arm, help to better understand barriers to and motivations for adherence, and develop interventions to increase adherence for future trials.

Acquired immune deficiency appears to be associated with serious non-AIDS (SNA)-defining conditions such as cardiovascular disease, liver and renal insufficiency and non-AIDS-related malignancies. We analysed the incidence of, and factors associated with, several SNA events in the LATINA retrospective cohort.

Differential Matrix Riccati Equations play a fundamental role in control theory, for example, in optimal control, filtering and estimation, decoupling and order reduction, etc. One of the most popular codes to solve stiff Differential Matrix Riccati Equations (DMREs) is based on Backward Differentiation Formula (BDF). In previous papers the authors of this paper showed two algorithms for solving DMREs based on an iterative Generalized Minimum RESidual (GMRES) approach and on a Fixed-Point approach. In this paper we present two contributions to improve the above algorithms. Firstly six variants of previous algorithms are carried out by using one of above algorithms in the first step and another algorithm to carry out the other steps until reaching convergence. Numerous tests on four case studies have been done comparing both precision and computational costs of MATLAB implementations of the above algorithms. Experimental results show that in some cases these algorithms improve on the speed and convergence of the original algorithms. Secondly, using the previous experimental results and since all algorithms have a similar structure and there is no best algorithm to solve all problems, two general-purpose adaptive algorithms have been designed for selecting the most appropriate algorithm, which can be chosen using a parameter that indicates the stiffness of the DMRE to be solved.

Human T-cell lymphotropic virus type-II (HTLV-II) infection is endemic in indigenous groups in the Americas and injection drug users (IDUs) worldwide. In Peru, HTLV-II infection was previously identified in two indigenous Amazonians. We examined risk factors for HTLV-II infection in 2,703 Peruvian men who have sex with men (MSM): 35 (1.3%) were HTLV-II positive. HTLV-II infection was associated with syphilis, HSV-2 infection, unprotected receptive anal intercourse, and older age. This is the first report of HTLV-II in a non-indigenous non-IDU population in Peru. Additional studies are needed to determine if HTLV-II is a sexually transmitted infection in this and other sexually active populations.

In this work we show a portable sequential and a portable parallel algorithm for solving the inverse eigenproblem for real symmetric Toeplitz matrices. Both algorithms are based on Broyden's method for solving nonlinear systems. We reduced the computational cost for some problem sizes, and furthermore we managed to reduce spatial cost considerably, compared in both cases with parallel algorithms proposed by other authors and by us, although sometimes quasi-Newton methods (as Broyden) do not reach convergence in all the test cases. We have implemented the parallel algorithm using the parallel numerical linear algebra library SCALAPACK based on the MPI environment. Experimental results have been obtained using two different architectures: a shared memory multiprocessor, the SGI PowerChallenge, and a cluster of Pentium II PCs connected through a myrinet network. The algorithms obtained are scalable in all the cases. Copyright © 2004 John Wiley & Sons, Ltd.

ObjectivesThe relationship between sexual practices, identity and role among Latino men who have sex with men (MSM) and HIV risk is the subject of ongoing investigation but less is known about how these aspects of sexuality relate to human papilloma-virus (HPV), an independent risk factor for HIV. This observational study investigated the relationship between HPV and sexual practices, identity and role as well as other sexually transmitted infection (STI)/HIV risk factors among HIV-negative heterosexually and homosexually identified Peruvian MSM.SettingCommunity-based clinic for MSM in Lima, Peru.Participants756 subjects were screened based on inclusion criteria of: born anatomically male; age ≥18 years; had any anal intercourse with a man during the previous 12 months; residing in metropolitan Lima; HIV negative; willing to commit to twice-yearly clinic visits for 24 months; had not participated in an HIV or HPV vaccine study. 600/756 participants met the inclusion criteria and were enrolled, of whom 48% (284) identified as homosexual and 10% (57) as heterosexual, the basis of the analyses performed.ResultsCompared with homosexually identified MSM, heterosexually identified MSM had completed fewer years of formal education and were less likely to have: anogenital HPV or visible anal warts; given oral sex to a man; or used a condom with their most recent female sexual partner (all pConclusionsHPV burden, wart type (penile vs anal) and select HIV/STI risk behaviours differed between heterosexually and homosexually identified Peruvian MSM. Understanding the implications of these differences can lead to tailored HIV/STI prevention interventions for heterosexually identified MSM.Trial registration numberNCT01387412.

Alternatives to convenience sampling (CS) are needed for HIV/STI surveillance of most-at-risk populations in Latin America. We compared CS, time space sampling (TSS), and respondent driven sampling (RDS) for recruitment of men who have sex with men (MSM) and transgender women (TW) in Lima, Peru. During concurrent 60-day periods from June–August, 2011, we recruited MSM/TW for epidemiologic surveillance using CS, TSS, and RDS. A total of 748 participants were recruited through CS, 233 through TSS, and 127 through RDS. The TSS sample included the largest proportion of TW (30.7 %) and the lowest percentage of subjects who had previously participated in HIV/STI research (14.9 %). The prevalence of newly diagnosed HIV infection, according to participants’ self-reported previous HIV diagnosis, was highest among TSS recruits (17.9 %) compared with RDS (12.6 %) and CS (10.2 %). TSS identified diverse populations of MSM/TW with higher prevalences of HIV/STIs not accessed by other methods. Alternativos al muestreo por conveniencia son necesarios para la vigilancia de VIH/ITS en poblaciones de alto riesgo en Latinoamérica. Hicimos una comparación de Muestreo por Conveniencia (MC), Muestreo de Tiempo y Espacio (TSS) y Muestreo Dirigido por Participante (RDS) para reclutar hombres que tienen sexo con hombres (HSH) y Mujeres Trans en Lima, Perú. Durante periodos concurrentes de 60 días entre Junio y Agosto de 2011, reclutamos HSH y Mujeres Trans para una vigilancia centinela usando MC, TSS, y RDS. En total, reclutamos a 748 participantes por MC, 233 por TSS, y 127 por RDS. El muestreo de TSS contó con la proporción más grande de Mujeres Trans (30.7 %) y el porcentaje más pequeño de sujetos que participaron en investigaciones anteriores de VIH/ITS (14.9 %). La prevalencia de nuevos casos diagnosticados de VIH (según el auto-reporte de los participantes de su historia de VIH) fue más alto en los participantes reclutados por TSS (17.9 %) con respecto a RDS (12.6 %) y MC (10.2 %). TSS identificó a poblaciones de HSH y Mujeres Trans con alta prevalencia de VIH/ITS que no fueron reclutados por los otros métodos.

Children and adolescents spend an average of 7 h a day using electronic media which include television, radio, cellphones, computers, and handheld devices (1); it would be naive to think that time spent on these devices has no effects (2). Indeed, it is clear that media has an effect on all of us, especially, youth who have grown up in a world surrounded by electronic devices (3–5). Decades of study on media use indicate a profound effect on the lives, health, and well being of youth (1). In particular, findings from a large number of studies, though often subject to controversy, link media use to psychosocial (6, 7), behavioral, and health problems (8–10) in children and youth. Potential positive effects of media use have been less studied. Media entertains, teaches, is a tool for communication, and may also be used as a means to cope with stress. We propose a need for the development of a novel assessment scale that will facilitate studies of the role of electronic media as a youth coping strategy.

The association of socialization patterns with unprotected anal intercourse (UAI) and HIV/STI prevalence remains underexplored in men who have sex with men (MSM) and transgender women (TW) in developing country settings. We evaluated the correlation of UAI, HIV, and syphilis with MSM/TW venue attendance and social network size among high-risk MSM and TW in Peru according to self-reported sexual identity. Frequency of venue attendance and MSM/TW social network size were lowest among heterosexual MSM and highest among TW respondents. Attendance (frequent or occasional) at MSM/TW venues was associated with increased odds of insertive UAI among heterosexual participants. Frequent venue attendance was associated with increased odds of receptive UAI among gay/homosexual, bisexual, and TW participants. Further investigation of the differing socialization patterns and associations with HIV/STI transmission within subgroups of Peruvian MSM and TW will enable more effective prevention interventions for these populations.

Transformation acoustics focuses on the design of advanced acoustic devices by employing sophisticated mathematical transformation techniques for engineering acoustic metamaterials—materials artificially fabricated with extraordinary acoustic properties beyond those encountered in nature. We present differential-geometric methods together with a variational principle and show how they form the basis for a powerful framework to control acoustic waves in industrial applications. We conclude with a practical example and implement the acoustic wave equation within a uniform accelerating rigid frame (UAF). As expected, an acoustic event horizon emerges, i.e., a boundary in spacetime beyond which events cannot acoustically affect any outside observer.

While adverse conditions in a child’s life do not excuse inappropriate behavior, they may cause emotional and behavioral problems that require treatment as a preventive measure to reduce the likelihood of bullying. We aimed to identify differences in the psychosocial profiles of adolescents who classified themselves as bullies, victims, or bully-victims. We performed a cross-sectional study in which data were collected between January 2009 and January 2010 from seven university-based clinics in a large metropolitan area with a predominantly Mexican-American population. We collected data on physical aggression among adolescents who self-categorized into the following groups: uninvolved, bullies, victims, and bully-victims. We determined the psychosocial profiles of the adolescents based on responses to the Youth Self Report (YSR) and parent’s responses to the Child Behavior Checklist (CBCL). A one-way analysis of variance and multivariate regression analyses were performed to compare the various components of the psychosocial profiles among the groups. Our analysis of the CBCL and the YSR assessments identified differences between the uninvolved group and one or more of the other groups. No significant differences were observed among the bully, victim, and bully-victim groups based on the CBCL. We did find significant differences among those groups based on the YSR, however. Our results suggest that emotional and behavioral problems exist among bullies, victims, and bully-victims. Therefore, treatment should not focus only on the victims of bullying; treatment is equally important for the other groups (bullies and bully-victims). Failure to adequately treat the underlying problems experienced by all three groups of individuals could allow the problems of bullying to continue.

Remarkable progress in medicine has provided people with the potential for longer and healthier lives. However, health disparities (e.g., poverty, access to health care, educational inequalities, higher exposure to health risks, etc.), make individuals, families, and communities miss most of the benefits of this progress (1, 2). Pediatric populations are affected by these disparities during crucial years of development. The result is poor health or disease, which develops over short and/or long term periods (3–5). The adverse contributions of these disparities have a different effect on each individual. However, they have a powerful effect on pediatric outcomes. One of the most recognized factors associated with health disparities is the problem of poor communication with parents/caretakers. Poor communication prevents them from receiving health benefits, participating in research studies, and actively contributing to disease prevention and health care for their children (6–9). Decades of effort and research on strategies to reduce health disparities have led to inconclusive and conflicting results, and there has been little improvement in leading health indicators (10). Some interventions could have a true beneficial effect on the participants. However, it is possible that the findings have been affected by misclassification of outcomes, exposures, or health conditions due to assessment disparities (11–13).

Rectal douching has attracted recent interest as a possible rectal microbicide (RM) formulation since many men who have sex with men (MSM) practice the behaviour prior to receptive anal intercourse (RAI).1 Acceptability research on rectal douches used by MSM found that if douches were available as an RM, MSM would be highly likely to use them when condoms were not used.2 This study reports on the practice of rectal douching, and the acceptability of a hypothetical RM formulated as a rectal douche among Peruvian MSM, a population with an estimated HIV prevalence of 12.2% compared with 0.61% in the general population.3 This retrospective study was based on data collected from a convenience sample of 824 MSM reporting RAI from three Peruvian cities (Lima, the Pacific coast capital, and the …

Background Knowledge of a sex partner’s HIV serostatus can influence sexual behavior and inform harm-reduction strategies. We sought to determine how often Peruvian men who have sex with men (MSM) and transgender women (TW) knew the HIV serostatus of their sex partners, if this knowledge was associated with any predictive factors or unprotected anal intercourse (UAI), and if UAI was associated with partner serostatus. Methods We analyzed data from the 2008 Peruvian MSM Sentinel Surveillance Survey. Data were collected by CASI about each participant’s three most recent male sex partners. Primary outcome was knowledge of a partner's HIV test result. Multivariate analysis assessed the effect of age, education, sexual identity, number of male partners, alcohol use during intercourse, type of partnership and length of partnership using logistic regression. Results 735 participants provided data on 1,643 of their most recent sex partners from the last 3 months. 179/735 (24.4%) of all participants knew HIV test results for at least one of their 3 most recent partners, corresponding to 230/1643 (14.0%) of all sexual partnerships in the last 3 months. In multivariate analysis, casual (OR: 0.27, 95% CI: 0.17-0.42) and exchange sex (OR: 0.31, 95% CI: 0.11-0.88) partners, compared to stable partners, were negatively associated with knowledge of partner serostatus, whereas relationships lasting longer than one night (