bluuebunny/crossref_metadata_2025 huggingface dataset:
Risk assessment, prognosis and guideline implementation in pulmonary arterial hypertension
Authors: Boucly Athénaïs , Weatherald Jason , Savale Laurent , Jaïs Xavier , Cottin Vincent , Prevot Grégoire , Picard François , de Groote Pascal , Jevnikar Mitja , Bergot Emmanuel , Chaouat Ari , Chabanne Céline , Bourdin Arnaud , Parent Florence , Montani David , Simonneau Gérald , Humbert Marc , Sitbon Olivier
Published: August 2017

Current European guidelines recommend periodic risk assessment for patients with pulmonary arterial hypertension (PAH). The aim of our study was to determine the association between the number of low-risk criteria achieved within 1 year of diagnosis and long-term prognosis.

Incident patients with idiopathic, heritable and drug-induced PAH between 2006 and 2016 were analysed. The number of low-risk criteria present at diagnosis and at first re-evaluation were assessed: World Health Organization (WHO)/New York Heart Association (NYHA) functional class I or II, 6-min walking distance (6MWD) >440 m, right atrial pressure <8 mmHg and cardiac index ≥2.5 L·min−1·m−2.

1017 patients were included (mean age 57 years, 59% female, 75% idiopathic PAH). After a median follow-up of 34 months, 238 (23%) patients had died. Each of the four low-risk criteria independently predicted transplant-free survival at first re-evaluation. The number of low-risk criteria present at diagnosis (p<0.001) and at first re-evaluation (p<0.001) discriminated the risk of death or lung transplantation. In addition, in a subgroup of 603 patients with brain natriuretic peptide (BNP) or N-terminal pro-brain natriuretic peptide (NT-proBNP) measurements, the number of three noninvasive criteria (WHO/NYHA functional class, 6MWD and BNP/NT-proBNP) present at first re-evaluation discriminated prognostic groups (p<0.001).

A simplified risk assessment tool that quantifies the number of low-risk criteria present accurately predicted transplant-free survival in PAH.
Temporal divergence of changes in pain and pain-free grip strength after manual acupuncture or electroacupuncture: an experimental study in people with lateral epicondylalgia
Authors: Jeon Jaewon , Bussin Erin , Scott Alex
Published: August 2017

Background

The objective of this study was to examine, in individuals with lateral epicondylalgia (LE), the acute time course of acupuncture-induced hypoalgesia and change in pain-free grip strength (PFGS).

Methods

This was an experimental study, conducted at a single research center in Vancouver, BC. Twenty-one participants with unilateral LE lasting more than 6 weeks duration were enrolled. Participants received a single treatment of acupuncture (either electroacupuncture, 10–30 Hz, or manual acupuncture, assigned randomly). The primary outcome measure was pain level (0–10) during tendon loading (while making a fist) immediately after treatment, and over a 72 h follow-up period. Secondary outcome measures included pain-free grip strength (N).

Results

There was a small but statistically significant reduction in participants’ perceived pain level immediately after acupuncture (mean improvement of 1.2, 95% CI 0.45–1.9). This change in pain was not accompanied by a change in PFGS. No difference was observed between the two types of acupuncture at any time point.

Conclusions

The use of acupuncture or electroacupuncture, as administered in the current study, is unlikely to acutely enhance the ability of people with LE to engage in pain-free rehabilitation exercise.

Trial registration Registered February 25, 2015. ISRCTN14667535, http://www.isrctn.com/ISRCTN14667535
The role of lipids in corneal diseases and dystrophies: a systematic review
Authors: Rowsey Tyler G. , Karamichos Dimitrios
Published: August 2017

Corneal diseases are an extensive cause of blindness worldwide and continue to persist as a challenging public health concern. Recently, various lipid‐based therapies have been advocated for the modulation of corneal diseases; however, the number of studies is still very limited. Here we focus on developments and challenges on lipid‐based therapies for dry eye disease, diabetic neuropathy, and Fuchs’ endothelial corneal dystrophy. All three diseases are highly prevalent conditions and involve corneal stress and inflammation. Lipid‐based therapeutics discussed includes cyclooxygenase inhibitors, essential fatty acids, and resolvin analogs. Lipids also show increasing promise as biomarkers of disease and are explored in this review.
MA-XRF imaging on René Magritte’s La condition humaine: insights into the artist’s palette and technique and the discovery of a third quarter of La pose enchantée
Authors: da Silva Alice Tavares , Legrand Stijn , Van der Snickt Geert , Featherstone Rupert , Janssens Koen , Bottinelli Giorgia
Published: August 2017

Magritte’s composition La condition humaine, 1935 was found to conceal under its paint layers an entire quarter of a lost composition by the artist, until recently only known from a small black/white catalogue illustration—La pose enchantée, 1927. This study is the latest contribution to the discovery of the artist’s missing painting, now known to have been cut into four parts and re-used by Magritte as the support for new compositions. Non-destructive analytical and examination methods and specifically macroscopic X-ray fluorescence (MAXRF) scanning and conventional X-ray radiography (XRR) were the two non-destructive analytical and examination methods used to study both compositions and add to the existing knowledge on the artist’s palette during both periods. The first method is capable of identifying the presence and the distribution of key chemical elements present in artists’ materials. In some instances elemental mapping provided useful information on the hidden painting, but conventional X-ray radiography (XRR) enabled a better visualisation of the form and paint application of the underlying composition. Furthermore, the turnover edges of the canvas reveal after over 80 years the artist’s palette directly to the viewer. Additional XRF scanning of this exposed paint has confirmed and added to the existing research published to date of this lost painting, including a proposed colour reconstruction, but at the same time highlighting the need for further analytical research involving both non-destructive point analysis and the use of paint samples.
A DREAM Challenge to Build Prediction Models for Short-Term Discontinuation of Docetaxel in Metastatic Castration-Resistant Prostate Cancer
Authors: Seyednasrollah Fatemeh , Koestler Devin C. , Wang Tao , Piccolo Stephen R. , Vega Roberto , Greiner Russell , Fuchs Christiane , Gofer Eyal , Kumar Luke , Wolfinger Russell D. , Kanigel Winner Kimberly , Bare Chris , Neto Elias Chaibub , Yu Thomas , Shen Liji , Abdallah Kald , Norman Thea , Stolovitzky Gustavo , Soule Howard R. , Sweeney Christopher J. , Ryan Charles J. , Scher Howard I. , Sartor Oliver , Elo Laura L. , Zhou Fang Liz , Guinney Justin , Costello James C. ,   Prostate Cancer DREAM Challenge Community
Published: August 2017

Purpose

Docetaxel has a demonstrated survival benefit for patients with metastatic castration-resistant prostate cancer (mCRPC); however, 10% to 20% of patients discontinue docetaxel prematurely because of toxicity-induced adverse events, and the management of risk factors for toxicity remains a challenge.

Patients and Methods

The comparator arms of four phase III clinical trials in first-line mCRPC were collected, annotated, and compiled, with a total of 2,070 patients. Early discontinuation was defined as treatment stoppage within 3 months as a result of adverse treatment effects; 10% of patients discontinued treatment. We designed an open-data, crowd-sourced DREAM Challenge for developing models with which to predict early discontinuation of docetaxel treatment. Clinical features for all four trials and outcomes for three of the four trials were made publicly available, with the outcomes of the fourth trial held back for unbiased model evaluation. Challenge participants from around the world trained models and submitted their predictions. Area under the precision-recall curve was the primary metric used for performance assessment.

Results

In total, 34 separate teams submitted predictions. Seven models with statistically similar area under precision-recall curves (Bayes factor ≤ 3) outperformed all other models. A postchallenge analysis of risk prediction using these seven models revealed three patient subgroups: high risk, low risk, or discordant risk. Early discontinuation events were two times higher in the high-risk subgroup compared with the low-risk subgroup. Simulation studies demonstrated that use of patient discontinuation prediction models could reduce patient enrollment in clinical trials without the loss of statistical power.

Conclusion

This work represents a successful collaboration between 34 international teams that leveraged open clinical trial data. Our results demonstrate that routinely collected clinical features can be used to identify patients with mCRPC who are likely to discontinue treatment because of adverse events and establishes a robust benchmark with implications for clinical trial design.
Screening and purification of natural products from actinomycetes that affect the cell shape of fission yeast
Authors: Lewis Richard A. , Li Juanjuan , Allenby Nicholas E. E. , Errington Jeffery , Hayles Jacqueline , Nurse Paul
Published: August 2017

This study was designed to identify bioactive compounds that alter the cellular shape of the fission yeast Schizosaccharomyces pombe by affecting functions involved in the cell cycle or cell morphogenesis. We used a multidrug-sensitive fission yeast strain, SAK950 to screen a library of 657 actinomycete bacteria and identified 242 strains that induced eight different major shape phenotypes in S. pombe. These include the typical cell cycle-related phenotype of elongated cells, and the cell morphology-related phenotype of rounded cells. As a proof of principle, we purified four of these activities, one of which is a novel compound and three that are previously known compounds, leptomycin B, streptonigrin and cycloheximide. In this study, we have also shown novel effects for two of these compounds, leptomycin B and cycloheximide. The identification of these four compounds and the explanation of the S. pombe phenotypes in terms of their known, or predicted bioactivities, confirm the effectiveness of this approach.
Targeting of the Drosophila protein CG2254/Ldsdh1 to a subset of lipid droplets
Authors: Thul Peter J. , Tschapalda Kirsten , Kolkhof Petra , Thiam Abdou Rachid , Oberer Monika , Beller Mathias
Published: August 2017

Lipid droplets (LDs) are the principal organelles of lipid storage. They consist of a hydrophobic core of storage lipids, surrounded by a phospholipid monolayer with proteins attached. While some of these proteins are known to be essential for the regulation of cellular and organismic lipid metabolism, key questions concerning LD protein function, such as their targeting to LDs, are still unanswered. Intriguingly, some proteins are restricted to subsets of LDs by an as-yet-unknown mechanism. This finding makes LD targeting even more complex. Here, we characterize the Drosophila protein CG2254, which is targeted to subsets of LDs in cultured cells and in different larval Drosophila tissues, where the prevalence of subsets of LDs appears highly dynamic. We find that an amphipathic amino acid stretch mediates CG2254 LD localization. Additionally, we identified a juxtaposed sequence stretch limiting CG2254 localization to a subset of LDs. This sequence is sufficient to restrict a chimeric protein consisting of the subset-targeting sequence introduced to an otherwise pan-LD-localized protein sequence to a subset of LDs. Based on its subcellular localization and annotated function, we suggest that CG2254 is renamed Lipid droplet subset dehydrogenase 1 (Ldsdh1).
Arabidopsis thaliana ACS8 plays a crucial role in the early biosynthesis of ethylene elicited by Cu2+ ions
Authors: Zhang Baogang , Liu Haifeng , Ding Xinhua , Qiu Jiajia , Zhang Min , Chu Zhaohui
Published: August 2017

Cu2+ ions are required by all living organisms and play important roles in many bactericides and fungicides. We previously reported that Cu2+ can elicit defense responses, which are dependent on the ethylene signaling pathway in Arabidopsis. However, the mechanism by which Cu2+ elicits the biosynthesis of ethylene remains unclear. Here, we show that CuSO4 treatment rapidly increases the production of ethylene. In addition, it upregulates the expression of several defense-related genes and ethylene biosynthesis genes, including genes encoding S-adenosylmethionine synthase, 1-aminocyclopropane-1-carboxylate (ACC) synthase (ACS) and ACC oxidase. Among these genes, Arabidopsis thaliana (At)ACS8 was identified as essential for the defense response and early ethylene biosynthesis induced by Cu2+. Furthermore, Cu2+-induced AtACS8 expression depended on the copper-response cis-element (CuRE) in the promoter of AtACS8. Our study indicates that Cu2+ specifically activates the expression of AtACS8 to promote the early biosynthesis of ethylene that elicits plant immunity in Arabidopsis plants.
Integrated Imaging Characterization of Adrenal Adenoma: False-Positive Metaiodobenzylguanidine (MIBG) Findings of Adrenal Scintigraphy
Authors: Dell’Aversana Serena , Coppola Milena , Balestrieri Umberto , Mainenti Pier Paolo , Pascale Carmen , Imbriaco Massimo , Chianca Vito , Romeo Valeria , Pellegrino Teresa , Mainolfi Ciro , Maurea Simone
Published: August 2017

Background: Evaluation of a patient with melanoma in whom an adrenal mass was detected on CT and MR during follow-up and further characterized with PET-CT and MIBG scintigraphy.

Case Report: In this case report, we describe a patient with melanoma in whom an adrenal mass was detected on CT and MRI during post-surgical follow-up and was further characterized with radionuclide studies consisting of PET-CT and MIBG scintigraphy. Although the results of imaging studies suggested that the mass was a pheochromocytoma, a cortical adrenal adenoma was histologically proven.

Conclusions: Integrated structural and functional imaging is recommended to characterize adrenal tumors; however, mistakes may occur and therefore careful imaging evaluation is required.
ChemMaps: Towards an approach for visualizing the chemical space based on adaptive satellite compounds
Authors: Naveja J. Jesús , Medina-Franco José L.
Published: August 2017

We present a novel approach called ChemMaps for visualizing chemical space based on the similarity matrix of compound datasets generated with molecular fingerprints’ similarity. The method uses a ‘satellites’ approach, where satellites are, in principle, molecules whose similarity to the rest of the molecules in the database provides sufficient information for generating a visualization of the chemical space. Such an approach could help make chemical space visualizations more efficient. We hereby describe a proof-of-principle application of the method to various databases that have different diversity measures. Unsurprisingly, we found the method works better with databases that have low 2D diversity. 3D diversity played a secondary role, although it seems to be more relevant as 2D diversity increases. For less diverse datasets, taking as few as 25% satellites seems to be sufficient for a fair depiction of the chemical space. We propose to iteratively increase the satellites number by a factor of 5% relative to the whole database, and stop when the new and the prior chemical space correlate highly. This Research Note represents a first exploratory step, prior to the full application of this method for several datasets.
Condições socioeconômicas e prática de atividades físicas em adultos e idosos: uma revisão sistemática
Authors: Rodrigues Phillipe Ferreira , Melo Marcelo , Assis Monique , Oliveira Alexandre
Published: August 2017

Esta revisão sistemática tem como objetivo analisar a relação entre os níveis de prática de atividades físicas e as condições sociais. Foi realizada uma busca na base de dados Pubmed e Scielo até Maio de 2015, utilizando as palavras chaves: physical activity, physical exercise, sedentary lifestyle, sedentay behaviour, socioeconomic status e socioeconomic factors. Os artigos foram analisados utilizando os critérios de inclusão: a) mostrar de forma explícita que investigavam tais associações; b) amostra com idade superior a 18 anos; c) redigidos em língua inglesa e portuguesa; d) data de publicação a partir do ano 2005. Foram adotados os seguintes critérios de exclusão: a) artigos que investigavam tais associações, mas envolviam outras síndromes e/ou doenças; b) estudos de revisão. Foram utilizados os parâmetros do Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) composto por uma lista de verificação de 22 itens a fim de analisar a qualidade dos estudos. Foram identificados 573 artigos. Após análise integral, restaram 43 artigos para a revisão. Esta revisão identifica que os indivíduos de menor escolaridade e renda, com pior qualificação profissional estão sujeitos a prática insuficiente de atividade física no lazer e por sua vez a uma maior sobrecarga ocupacional e de deslocamento.
Concordância entre dois critérios de classificação da atividade física e fatores associados em adolescentes
Authors: Pinto André de Araújo , Claumann Gaia Salvador , Puga Barbosa Rita Maria dos Santos , Nahas Markus Vinicius , Angelo Hector Cris Colares de , Pelegrini Andreia
Published: August 2017

O objetivo deste estudo foi analisar a concordância entre dois critérios de classificação da atividade física (AF) e os respectivos fatores associados. Os participantes foram 2.517 adolescentes amazonenses (14 a 19 anos de idade). O nível de AF e as variáveis independentes (sexo, faixa etária, ano escolar, turno de estudo, renda familiar, escolaridade materna e situação ocupacional) foram coletados por meio de questionário. O coeficiente kappa e a regressão logística binária foram empregados, respectivamente, para analisar a concordância entre as prevalências e os fatores associados aos dois critérios de classificação da AF (300 e 420 minutos/semana). Verificou-se moderada concordância entre os critérios (kappa = 0,58; p< 0,001) para classificação do nível de AF, com diferença de 8,5 pontos percentuais entre as prevalências, sendo que para os 300 e 420 minutos/semana foram classificados como fisicamente ativos 15,5% (IC95% = 14,2-16,7) e 7,0% (IC95% = 6,0-7,0) dos participantes, respectivamente. Os adolescentes do sexo masculino e os que não trabalhavam tiveram mais chances de serem fisicamente ativos em ambos os critérios. Os adolescentes mais novos (14 a 16 anos) tiveram mais chances de serem fisicamente ativos no critério de 300 minutos/semana. O ano escolar, turno de estudo, renda familiar e escolaridade materna não se associaram aos critérios utilizados. A concordância entre os dois critérios de classificação do nível de AF foi moderada e os fatores associados foram semelhantes em ambos os critérios, com exceção da faixa etária.
Logical model of a behavior change program for community intervention – Active Life Improving Health – VAMOS
Authors: Benedetti Tânia , Manta Sofia , Gomez Luiz , Rech Cassiano
Published: August 2017

The present study aimed to present a Logic Model (LM) of the “Vida Ativa Melhorando a Saúde” (VAMOS – Active Life Improving Health) program for its application in community interventions in adults and old age in Brazil. The VAMOS program purpose is to motivate people to have a healthier lifestyle. It is divided in 12 group meetings usually held weekly, varying from three to five months of duration. VAMOS is guided by specific booklets and conducted by health professionals with prior certification. The LM consists of activities (advertising, meetings, community outreach), products (financial resources, promotion, increase in attendance) and short, medium and long term objectives (adoption of the program, knowledge and empowerment of participants). Participants of the VAMOS program maintained their physical activity levels for longer when compared with traditional and control groups. VAMOS is under expansion in Brazil, supporting behavior changes in order to reach a healthier lifestyle.
Spectral Gap of the Erlang A Model in the Halfin-Whitt Regime
Authors: van Leeuwaarden Johan S. H. , Knessl Charles
Published: August 2017

We consider a hybrid diffusion process that is a combination of two Ornstein-Uhlenbeck processes with different restraining forces. This process serves as the heavy-traffic approximation to the Markovian many-server queue with abandonments in the critical Halfin-Whitt regime. We obtain an expression for the Laplace transform of the time-dependent probability distribution, from which the spectral gap is explicitly characterized. The spectral gap gives the exponential rate of convergence to equilibrium. We further give various asymptotic results for the spectral gap, in the limits of small and large abandonment effects. It turns out that convergence to equilibrium becomes extremely slow for overloaded systems with small abandonment effects.
Portfolio Rebalancing Error with Jumps and Mean Reversion in Asset Prices
Authors: Glasserman Paul , Xu Xingbo
Published: August 2017

We analyze the error between a discretely rebalanced portfolio and its continuously rebalanced counterpart in the presence of jumps or mean-reversion in the underlying asset dynamics. With discrete rebalancing, the portfolio’s composition is restored to a set of fixed target weights at discrete intervals; with continuous rebalancing, the target weights are maintained at all times. We examine the difference between the two portfolios as the number of discrete rebalancing dates increases. With either mean reversion or jumps, we derive the limiting variance of the relative error between the two portfolios. With mean reversion and no jumps, we show that the scaled limiting error is asymptotically normal and independent of the level of the continuously rebalanced portfolio. With jumps, the scaled relative error converges in distribution to the sum of a normal random variable and a compound Poisson random variable. For both the mean-reverting and jump-diffusion cases, we derive “volatility adjustments” to improve the approximation of the discretely rebalanced portfolio by the continuously rebalanced portfolio, based on on the limiting covariance between the relative rebalancing error and the level of the continuously rebalanced portfolio. These results are based on strong approximation results for jump-diffusion processes.
Subsampling Algorithms for Semidefinite Programming
Authors: d’Aspremont Alexandre
Published: August 2017

We derive a stochastic gradient algorithm for semidefinite optimization using randomization techniques. The algorithm uses subsampling to reduce the computational cost of each iteration and the subsampling ratio explicitly controls granularity, i.e. the tradeoff between cost per iteration and total number of iterations. Furthermore, the total computational cost is directly proportional to the complexity (i.e. rank) of the solution. We study numerical performance on some large-scale problems arising in statistical learning.
Many-server Queues with Customer Abandonment: Numerical Analysis of their Diffusion Model
Authors: Dai J. G. , He Shuangchi
Published: August 2017

We use a multidimensional diffusion process to approximate the dynamics of a queue served by many parallel servers. Waiting customers in this queue may abandon the system without service. To analyze the diffusion model, we develop a numerical algorithm for computing its stationary distribution. A crucial part of the algorithm is choosing an appropriate reference density. Using a conjecture on the tail behavior of the limit queue length process, we propose a systematic approach to constructing a reference density. With the proposed reference density, the algorithm is shown to converge quickly in numerical experiments. These experiments demonstrate that the diffusion model is a satisfactory approximation for many-server queues, sometimes for queues with as few as twenty servers.
Bandwidth Sharing Networks with Multiscale Traffic
Authors: Feuillet Mathieu , Jonckheere Matthieu , Prabhu Balakrishna
Published: August 2017

In multi-class communication networks, traffic surges due to one class of users can significantly degrade the performance for other classes. During these transient periods, it is thus of crucial importance to implement priority mechanisms that conserve the quality of service experienced by the affected classes, while ensuring that the temporarily unstable class is not entirely neglected. In this paper, we examine the complex interaction occurring between several classes of traffic when classes obtain bandwidth proportionally to their incoming traffic. We characterize the evolution of the performance measures of the network from the moment the initial surge takes place until the system reaches its equilibrium. Using a time-space-transition-scaling, we show that the trajectories of the temporarily unstable class can be described by a differential equation, while those of the stable classes retain their stochastic nature. In particular, we show that the temporarily unstable class evolves at a time-scale which is much slower than that of the stable classes. Although the time-scales decouple, the dynamics of the temporarily unstable and the stable classes continue to influence one another. We further proceed to characterize the obtained differential equations for several simple network examples. In particular, the macroscopic asymptotic behavior of the unstable class allows us to gain important qualitative insights on how the bandwidth allocation affects performance. We illustrate these results on several toy examples and we finally build a penalization rule using these results for a network integrating streaming and surging elastic traffic.
Some New Results on Information Percolation
Authors: Bélanger Alain , Giroux Gaston
Published: August 2017

We study the dynamics of a large number, N, of investors which have meetings by groups of m. We obtain an explicit formula for the solution of the associated non-linear system of differential equations. This formula is tractable and it enables us to show the asymptotic stability of a large class of models. One of those models can be thought of as an interacting portfolio market.
Learning Loosely Connected Markov Random Fields
Authors: Wu Rui , Srikant R. , Ni Jian
Published: August 2017

We consider the structure learning problem for graphical models that we call loosely connected Markov random fields, in which the number of short paths between any pair of nodes is small, and present a new conditional independence test based algorithm for learning the underlying graph structure. The novel maximization step in our algorithm ensures that the true edges are detected correctly even when there are short cycles in the graph. The number of samples required by our algorithm is C log p, where p is the size of the graph and the constant C depends on the parameters of the model. We show that several previously studied models are examples of loosely connected Markov random fields, and our algorithm achieves the same or lower computational complexity than the previously designed algorithms for individual cases. We also get new results for more general graphical models, in particular, our algorithm learns general Ising models on the Erdős-Rényi random graph [Formula: see text] correctly with running time O(np5).
On the Convergence of Simulation-based Iterative Methods for Solving Singular Linear Systems
Authors: Wang Mengdi , Bertsekas Dimitri P.
Published: August 2017

We consider the simulation-based solution of linear systems of equations, Ax = b, of various types frequently arising in large-scale applications, where A is singular. We show that the convergence properties of iterative solution methods are frequently lost when they are implemented with simulation (e.g., using sample average approximation), as is often done in important classes of large-scale problems. We focus on special cases of algorithms for singular systems, including some arising in least squares problems and approximate dynamic programming, where convergence of the residual sequence {Axk − b} may be obtained, while the sequence of iterates {xk} may diverge. For some of these special cases, under additional assumptions, we show that the iterate sequence is guaranteed to converge. For situations where the iterates diverge but the residuals converge to zero, we propose schemes for extracting from the divergent sequence another sequence that converges to a solution of Ax = b.
Power Identities for Lévy Risk Models Under Taxation and Capital Injections
Authors: Albrecher Hansjörg , Ivanovs Jevgenijs
Published: August 2017

In this paper we study a spectrally negative Lévy process which is refracted at its running maximum and at the same time reflected from below at a certain level. Such a process can for instance be used to model an insurance surplus process subject to tax payments according to a loss-carry-forward scheme together with the flow of minimal capital injections required to keep the surplus process non-negative. We characterize the first passage time over an arbitrary level and the cumulative amount of injected capital up to this time by their joint Laplace transform, and show that it satisfies a simple power relation to the case without refraction, generalizing results by Albrecher and Hipp (2007) and Albrecher, Renaud and Zhou (2008). It turns out that this identity can also be extended to a certain type of refraction from below. The net present value of tax collected before the cumulative injected capital exceeds a certain amount is determined, and a numerical illustration is provided.
Fluid Limits for Overloaded Multiclass FIFO Single-Server Queues with General Abandonment
Authors: Jennings Otis B. , Puha Amber L.
Published: August 2017

We consider an overloaded multiclass nonidling first-in-first-out single-server queue with abandonment. The interarrival times, service times, and deadline times are sequences of independent and identically, but generally distributed random variables. In prior work, Jennings and Reed studied the workload process associated with this queue. Under mild conditions, they establish both a functional law of large numbers and a functional central limit theorem for this process. We build on that work here. For this, we consider a more detailed description of the system state given by K finite, nonnegative Borel measures on the nonnegative quadrant, one for each job class. For each time and job class, the associated measure has a unit atom associated with each job of that class in the system at the coordinates determined by what are referred to as the residual virtual sojourn time and residual patience time of that job. Under mild conditions, we prove a functional law of large numbers for this measure-valued state descriptor. This yields approximations for related processes such as the queue lengths and abandoning queue lengths. An interesting characteristic of these approximations is that they depend on the deadline distributions in their entirety.
Giant Component in Random Multipartite Graphs with given Degree Sequences
Authors: Gamarnik David , Misra Sidhant
Published: August 2017

We study the problem of the existence of a giant component in a random multipartite graph. We consider a random multipartite graph with p parts generated according to a given degree sequence [Formula: see text] which denotes the number of vertices in part i of the multipartite graph with degree given by the vector d in an n-node graph. We assume that the empirical distribution of the degree sequence converges to a limiting probability distribution. Under certain mild regularity assumptions, we characterize the conditions under which, with high probability, there exists a component of linear size. The characterization involves checking whether the Perron-Frobenius norm of the matrix of means of a certain associated edge-biased distribution is greater than unity. We also specify the size of the giant component when it exists. We use the exploration process of Molloy and Reed Molloy and Reed (1995) to analyze the size of components in the random graph. The main challenges arise due to the multidimensionality of the random processes involved which prevents us from directly applying the techniques from the standard unipartite case. In this paper we use techniques from the theory of multidimensional Galton-Watson processes along with Lyapunov function technique to overcome the challenges.
Waves in a Spatial Queue
Authors: Aldous David
Published: August 2017

Envisaging a physical queue of humans, we model a long queue by a continuous-space model in which, when a customer moves forward, they stop a random distance behind the previous customer, but do not move at all if their distance behind the previous customer is below a threshold. The latter assumption leads to “waves” of motion in which only some random number W of customers move. We prove that ℙ(W > k) decreases as order k− 1/2; in other words, for large k the k’th customer moves on average only once every order k1/2 service times. A more refined analysis relies on a non-obvious asymptotic relation to the coalescing Brownian motion process; we give a careful outline of such an analysis without attending to all the technical details.
Scaling Limits for Infinite-server Systems in a Random Environment
Authors: Heemskerk Mariska , van Leeuwaarden Johan , Mandjes Michel
Published: August 2017

This paper studies the effect of an overdispersed arrival process on the performance of an infinite-server system. In our setup, a random environment is modeled by drawing an arrival rate Λ from a given distribution every Δ time units, yielding an i.i.d. sequence of arrival rates Λ1,Λ2, …. Applying a martingale central limit theorem, we obtain a functional central limit theorem for the scaled queue length process. We proceed to large deviations and derive the logarithmic asymptotics of the queue length’s tail probabilities. As it turns out, in a rapidly changing environment (i.e., Δ is small relative to Λ) the overdispersion of the arrival process hardly affects system behavior, whereas in a slowly changing random environment it is fundamentally different; this general finding applies to both the central limit and the large deviations regime. We extend our results to the setting where each arrival creates a job in multiple infinite-server queues.
Asymptotic Expansion of Stationary Distribution for Reflected Brownian Motion in the Quarter Plane via Analytic Approach
Authors: Franceschi Sandro , Kourkova Irina
Published: August 2017

Brownian motion in [Formula: see text] with covariance matrix Σ and drift μ in the interior and reflection matrix R from the axes is considered. The asymptotic expansion of the stationary distribution density along all paths in [Formula: see text] is found and its main term is identified depending on parameters (Σ, μ, R). For this purpose the analytic approach of Fayolle, Iasnogorodski and Malyshev in [12] and [36], restricted essentially up to now to discrete random walks in [Formula: see text] with jumps to the nearest-neighbors in the interior is developed in this article for diffusion processes on [Formula: see text] with reflections on the axes.
Everyone’s searching for a saviour: Film, theology and media ecology
Authors: Soukup Paul A.
Published: August 2017

Christian theology has employed almost all communication media and techiques to aid its reflection on belief. Its twentieth century fascination with film illustrates how media ecology can inform both theology’s practices and theology’s key concepts, such as sacramentality. Looking at filmic theology through a media ecology lens reveals that film can have religious significance in a number of ways: relationally, ritually, narratively, symbolically, performatively and imaginatively.
Information is not wisdom, convergence is not integrity: Proverbs for an era of digital humanism
Authors: Healey Kevin
Published: August 2017

The techno-utopianism of Silicon Valley constitutes a quasi-religious ideology with economic and moral dimensions. While the ‘catechism’ of free market ideology has long historical roots, digital culture adds a moral dimension that equates the development of networked information systems with the achievement of human virtue. This article calls such assumptions into question by positing three guiding ‘proverbs’: Information is not wisdom; Convergence is not integrity; Transparency is not authenticity. Exposition of these proverbs highlights inequities of power and class privilege obscured by techno-utopian rhetoric, and calls for an approach to technological development grounded in the psychology of mature human spirituality.
Estrategia formativa con una herramienta tecnológica de contenido digital para la prevención de hipertensión arterial en adolescentes - Formative strategy with a technological tool of digital content for the prevention of hypertension in adolescents
Authors: Caviativa-Castro Yaneth , Jaramillo G Valentino
Published: August 2017

La estrategia formativa a desarrollar es un objeto virtual como estrategia en la promoción y prevención de la hipertensión arterial en adolescentes de 14 a 17 años de edad; como herramienta pedagógica, didáctica y tecnológica para el fortalecimiento de los conceptos , se implementará en el décimo grado en el colegio Manuela Beltrán jornada tarde debido a los factores de riesgo a los que están expuestos   para desarrollar estas enfermedades como: mala alimentación, poco ejercicio y uso de sustancias sicoactivas, entre otras. Es un estudio cualitativo descriptivo, el modelo investigativo se basa en un estudio de caso donde se obtuvieron resultados positivos con ayuda de la herramienta de aprendizaje.
Estrategias tecnológicas para el fomento de la conservación ambiental -Technological strategies for the promotion of environmental conservation
Authors: Pascuas-Rengifo Yois , González A Mayra , Perdomo O Karen
Published: August 2017

El presente artículo tiene como objetivo identificar estrategias tecnológicas enfocadas al fomento de la conservación del medio ambiente, haciendo énfasis en la articulación de las TIC al desarrollo sostenible. A su vez se resalta su importancia como mediación para la interacción y entendimiento de las diferentes estrategias de conservación ambiental; así mismo, la emergencia de las ciudades inteligentes como alternativa de articulación de las TIC en diferentes contextos para el mejoramiento de la calidad de vida, encaminadas a disminuir la degradación ambiental y ampliar los impactos ambientales positivos.
Aplicación móvil de realidad aumentada para la ubicación de las aulas de clase en el Campus Porvenir de la Universidad de la Amazonia - Mobile augmented reality application for the location of classrooms at the Campus Porvenir of the University of the Amazon
Authors: Sandoval Carlos Alberto , Carvajal-Beltrán Leidy Vanessa
Published: August 2017

El presente trabajo es una investigación del semillero de Sistemas con Aplicación de la Realidad Aumentada (SARA), tiene como propósito desarrollar una aplicación móvil de realidad aumentada para la ubicación de las aulas de clase en el Campus Porvenir de la Universidad de la Amazonia. Se desarrolla mediante un diseño metodológico exploratorio y proyectivo, con un enfoque sistémico. La propuesta busca enseñar de forma dinámica y autónoma a ubicarse dentro de los diferentes espacios físicos del Campus Porvenir, haciendo uso de tecnologías de la información y la comunicación TIC.
Créditos
Authors: Gallego Patricia
Published: August 2017

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FÍSICA, CUENTOS Y POEMAS
Authors: Valencia M Harol Y. , Millan Diana A.
Published: August 2017

Se diseña e implementa una estrategia didáctica a través de los cuentos y poemas, como representaciones del lenguaje, para la enseñanza de la física. La expresión a través de la palabra facilita la comprensión e interpretación de los conceptos, los estudiantes pueden plasmar sus sentimientos, sensaciones de belleza, creatividad, imaginación e influencia, haciendo uso de conceptos y definiciones del campo de la física. Estos cuentos y poemas se presentan de forma individual con los conceptos y teorías estudiadas durante el curso, luego se hace una corrección de estos conceptos, a partir de lo que el estudiante desea expresar, presentándose así una dinámica de proyecciones e introyecciones entre el estudiante y el docente. Siendo así una investigación de carácter exploratorio y comprensivo, de esta forma el estudio de caso es la herramienta apropiada.
VERIFICACIÓN DEL EFECTO FOTO ELÉCTRICO CON LUZ ULTRAVIOLETA
Authors: Marquez A. L.
Published: August 2017

Desde el punto de vista de estudiante se desarrollo un experimento para verificar el efecto fotoeléctrico con un montaje sencillo para aclarar dudas sobre este efecto y las frecuencias de onda en las cuales se puede presentar, de igual manera se plantea la conexión matemática entre la ecuación de Einstein y la ecuación de trabajo en función de la carga del electrón para analizar la viabilidad de la cuantificación experimental de esta comprobación.
Atlas web turístico de la reserva de la biosfera del Archipiélago de San Andrés
Authors: Rocha Salamanca Luz Ángela , Cardenas Contreras Andrés
Published: August 2017

En los últimos años los mapas en línea o mapas en la web se han convertido en una herramienta importante para la difusión de datos espaciales, especialmente en temas como el turismo, debido a que son más útiles y flexibles que los convencionales basados en las características intrínsecas que ellos poseen. Herramientas como los Sistemas de Información Geográfica (SIG) que enmarcan igualmente a los llamados SIG en línea (web- GIS o sic -web), permiten desarrollar diferentes aplicaciones basadas en información espacial como la producción de los atlas web, dentro de un ambiente académico.Este artículo presenta los resultados del proyecto de investigación Diseño de un atlas en línea para el Archipiélago de San Andrés y Providencia, cuyo objetivo principal se basó en el desarrollo conceptual y técnico del diseño de una interfaz dinámica e interactiva de un atlas turístico en línea, que permita de la difusión de información geográfica en la red y ayude a fomentar un sector turístico de Colombia como es el de San Andrés y Providencia.Un diseño integral del atlas incluye considerar los diferentes modelos, determinar el estado del conocimiento, caracterizar las variables para el caso de estudio, adquirir los datos en el trabajo de campo, definir y actualizar la información que hará parte del atlas en línea, con lo que se desarrolla un procedimiento cartográfico de elaboración y publicación de mapas en la red.
Desarrollo de un sistema de comunicación remota vía modem con un pc que se encuentra apagado
Authors: Mosquera Palacios Darin Jairo , Salcedo Parra Octavio , Patiño Bernal Marlon
Published: August 2017

El presente artículo, describe el diseño y desarrollo de una tarjeta para el encendido de un PC remoto vía MODEM como resultado parcial del proyecto de investigación Sistema de gestión en línea de un PC por Internet, donde se comunican dos computadores por Internet y se suple uno de los obstáculos que se presenta cuando una de las máquinas se encuentra fisicamente distante y apagada. Lo que busca este trabajo es no preocuparse por la máquina remota a gestionar, si no por qué tipo de información es la que se necesita intercambiar o software a instalar.
Elementos para el análisis del mercado en cadena agroindustrial. aplicación al caso de la cadena de la uchuva en la provincia de Sumapaz
Authors: Calderon María Eugenia , Buitrago Sandra Patricia , Orjuela Castro Javier Arturo
Published: August 2017

En este artículo los principales hallazgos del estudio adelantado en el marco del proyecto de investigación marco ¨Competitividad en la cadena agroindustrial de frutas y lácteos en Colombia¨, en lo que tiene que ver con el componente de mercadeo de uchuva en la provincia de sumapaz, Cundinamarca.Se identifican y caracterizan las variables relevantes para el análisis del mercadeo de uchuva en un entorno competitivo y, a partir de ello, se plantean estrategias para su mejora.
Contexto institucional para la introducción de la evaluación ambiental estratégica (eae) en Colombia.
Authors: Gómez Duque Jorge
Published: August 2017

Las posibilidades de introducir la Evaluación Ambiental Estratégica (EAE) en Colombia (la cual se aplica a nivel de políticas, planes y programas-PPP), implica analizar el contexto sociopolítico, los procesos de gestión en genral el entorno en que se desarrollan las políticas públicas, aún más considerando la variedad, entornos específicos, formas particulares de estructuración formal, diferentes modalidades de interdependencias, etc.
La generalización en cartografía básica y temática
Authors: Galvis Lagos María Fernanda
Published: August 2017

El conocimiento y explicación de la organización espacial y sus variaciones es inherente a la Geografía y constituye su esencia para la expresión gráfica (cartográfica). La organización espacial puede entenderse como una jerarquía encajonada de sistemas y subsistemas a diferentes escalas; por tanto requiere ser clasificada jerárquicamente y representada cartográficamente como espacios geográficos de diversos tamaños, dando cabida á la generalización cartográfica. Sin embargo, al revisar los materiales cartográficos prbducidos por diversas entidades nacionales es evidente el uso de clasificaciones planas o no jerarquizadas (a un único nivel). Este hecho obstaculiza el proceso de generalización cartográfica y presenta serias dificultades tanto conceptuales como de procedimiento en el momento de cambiar la escala cartográfica. En este trabajo se plantea una conceptualización de generalización cartográfica con base en la teoría jerárquicay la noción de nivel de resolución, y se muestra cómo la vocación aplicada o instrumental de la clasificación jerárquica es la cartográfica, puesto que cada nivel jerárquico necesita una dimensiórí espacial suficiente para expresarse.Definida la base conceptual, se propone un procedimiento de generalización cartográfica basado en un modelo jerárquico escalar, que define los conceptos que se desarrollan en cada nivel de la jerarquía y los rangos escalares en los que se representa cada nivel. Además se muestra el empleo correcto de las variables visuales que reflejan el nivel de la información y la clasificación jerárquica. La propuesta anterior se aplica en seis ejemplos de generalización para cartografia temática, en los cuales la clasificación jerárquica es fundamental para, a partir del nivel de mayor resolución, avanzar hacia niveles jerárquicos superiores que se representan en escalas cada vez menores.
La historia de la teoría electroquímica y su contribución a la promoción de la explicación científica en la química escolar
Authors: Camacho González Johanna
Published: August 2017

Esta investigación presenta los principales hallazgos referentes a ¿cómo se construyen las explicaciones científicas acerca de la Teoría Electroquímica en las clases de Educación Media? La investigación se sustenta en la actual necesidad de promover la explicación como una competencia científica y, en el uso de la historia de la ciencia, como área metacientífica que contribuye favorablemente a dicha necesidad. Este artículo presenta resultados de una investigación que se realizó en Santiago de Chile, a través de un estudio de casos colectivo, en el cual se pudieron evidenciar dos secuencias diferentes para la construcción de las explicaciones mediante la enseñanza de la teoría electroquímica.