bluuebunny/crossref_metadata_2025 huggingface dataset:
Transradial Delivery of a Renal Snorkel During Complex Endovascular Aortic Aneurysm Repair
Authors: Stern Jordan R. , Ellozy Sharif H.
Published: August 2017

Transradial access has been described in a variety of clinical contexts but has been rarely utilized for visceral artery interventions and during complex endovascular aortic aneurysm repair (EVAR) when upper extremity access is required. This is usually accomplished via brachial artery access, and although brachial access is generally safe and effective, radial access may offer some benefits with regard to patient comfort and potential complications. Here we report a case of successful delivery of a renal snorkel via a radial artery approach during EVAR. A 71-year-old man presented for endovascular repair of an asymptomatic abdominal aortic aneurysm. Anatomic limitations dictated the need for a left renal snorkel in order to augment the proximal seal zone. Via a right radial approach, a 6-Fr sheath and then a 6-mm iCast stent (Atrium Medical, Hudson, New Hampshire) were delivered into the left renal artery. Endovascular aortic aneurysm repair was then completed with a bifurcated Endurant stent graft (Medtronic, Fridley, Minnesota). The renal stent and aortic stent grafts were successfully deployed. Completion angiography demonstrated a patent left renal snorkel, with no evidence of endoleak. Hemostasis was achieved at the radial puncture site with no complications. This demonstrates the feasibility of radial artery access for the delivery of adjunctive stents during complex EVAR.
Principals’ leadership in Mexican upper high schools: The paradoxes between rules and practices
Authors: Santizo Rodall Claudia A , Ortega Salazar Sylvia B
Published: August 2017

This article discusses the type of organization and leadership that underlies a competency-based management rule established in Mexico (2008) applicable to principals in public upper high schools. This rule, identified as the 449 Agreement, describes competencies and communicates expected behavior. Implementation, however, is mediated by the principals’ interpretation, as found in the semi-structured interviews conducted with a group of selected acting principals.

The analysis of this management rule is based on a theory of decision-making and a theory of organizations where different assumptions on peoples’ behavior are made. We provide evidence to support the contention that each school principal acts according to its context, and that compliance with the Agreement is not facilitated by its rules design.

We conclude that the rules design of the competency-based management model in question is dominated by a perspective of personal heroic leadership that assumes an omniscient and omnipresent manager and that also promotes a centralized management model for all schools.

In future research, inquiry could focus on the question of whether transformational leadership based on motivation and instructional leadership based on guidance and coaching for teachers could also be nurtured by rules compatible with the pervasive normative leadership type.
Influence of contemporary leadership on job satisfaction, organizational commitment, and turnover intention
Authors: Kerdngern Nopphong , Thanitbenjasith Phithagorn
Published: August 2017

This empirical research investigates the influence of the construction project managers’ contemporary leadership (CL) on the job satisfaction (JS), organizational commitment (OC), and turnover intention (TI) of the civil engineers in the Thai setting. A sequential explanatory mixed method was used in the study whereby the quantitative research was carried out with a sample of 450 civil engineers using a validated questionnaire and a structural equation model. An in-depth interview with another 10 civil engineers was subsequently conducted and the qualitative findings compared against the quantitative results. The quantitative results revealed that CL exerted a direct positive influence on JS and OC and a direct negative influence on TI. The qualitative findings were mostly agreeable with the quantitative results except for the OC aspect where the interviewees attached the greatest value to the OC’s monetary components, as opposed to the quantitative results.
Armadillo Mapper
Authors: Feng Xiao , Castro Mariela C. , Linde Evan , Papeş Monica
Published: August 2017

Ecological niche modeling (ENM) uses species’ known occurrences and environmental variables to estimate potential geographic distributions. The potential distribution of a species can be updated and refined after new occurrences are collected; therefore, we developed an online application (Armadillo Mapper [AM]) that automatically updates the ecological niche model for the hairy long-nosed armadillo ( Dasypus pilosus) with new observations and provides a revised potential distribution map. AM can be used by researchers and conservation practitioners without a deep knowledge of geographic information system (GIS) techniques and ENM. Here, we introduce this online application and demonstrate the use of our application with a new observation of D. pilosus. AM has the potential to be extended to other species and to bridge the gap between distributional knowledge synthesized in a computer lab and conservation efforts carried out in the field.
Predicting two-year mortality from discharge after acute coronary syndrome: An internationally-based risk score
Authors: Pocock Stuart J , Huo Yong , Van de Werf Frans , Newsome Simon , Chin Chee Tang , Vega Ana Maria , Medina Jesús , Bueno Héctor
Published: August 2017

Background:

Long-term risk of post-discharge mortality associated with acute coronary syndrome remains a concern. The development of a model to reliably estimate two-year mortality risk from hospital discharge post-acute coronary syndrome will help guide treatment strategies.

Methods:

EPICOR (long-tErm follow uP of antithrombotic management patterns In acute CORonary syndrome patients, NCT01171404) and EPICOR Asia (EPICOR Asia, NCT01361386) are prospective observational studies of 23,489 patients hospitalized for an acute coronary syndrome event, who survived to discharge and were then followed up for two years. Patients were enrolled from 28 countries across Europe, Latin America and Asia. Risk scoring for two-year all-cause mortality risk was developed using identified predictive variables and forward stepwise Cox regression. Goodness-of-fit and discriminatory power was estimated.

Results:

Within two years of discharge 5.5% of patients died. We identified 17 independent mortality predictors: age, low ejection fraction, no coronary revascularization/thrombolysis, elevated serum creatinine, poor EQ-5D score, low haemoglobin, previous cardiac or chronic obstructive pulmonary disease, elevated blood glucose, on diuretics or an aldosterone inhibitor at discharge, male sex, low educational level, in-hospital cardiac complications, low body mass index, ST-segment elevation myocardial infarction diagnosis, and Killip class. Geographic variation in mortality risk was seen following adjustment for other predictive variables. The developed risk-scoring system provided excellent discrimination ( c-statistic=0.80, 95% confidence interval=0.79–0.82) with a steep gradient in two-year mortality risk: >25% (top decile) vs. ~1% (bottom quintile). A simplified risk model with 11 predictors gave only slightly weaker discrimination ( c-statistic=0.79, 95% confidence interval =0.78–0.81).

Conclusions:

This risk score for two-year post-discharge mortality in acute coronary syndrome patients ( www.acsrisk.org ) can facilitate identification of high-risk patients and help guide tailored secondary prevention measures.
The New Juan Crow? Unpacking the Links Between Discrimination and Crime for Latinxs
Authors: Isom Scott Deena
Published: August 2017

This study investigates the impact of various types of discrimination, including injustices from the police, as well as the conditioning effects of a positive ethnic identity on the likelihood of offending for Latinxs. Findings support the notion that discrimination from the police and everyday microaggressions are significant strains for Latinxs that increase their likelihood of offending. Anger is also found to be a significant driving factor. This study additionally adds to the growing body of mixed results around the impacts of ethnic identity, particularly for Latinxs, as it does not protect against the effects of discrimination for the current sample. This work is timely in the wake of the recent rhetoric around immigration, particularly from Latin American countries. With the rapid rise in Latinx incarceration, it is vital we understand the distinct factors that impact their likelihood of contact with the justice system to develop culturally competent intervention policies and counter the institutional racism driving the disparities.
Universal Design for Learning: Supporting College Inclusion for Students With Intellectual Disabilities
Authors: Love Matthew L. , Baker Joshua N. , Devine Stephanie
Published: August 2017

As college becomes an increasingly important prerequisite for employment, it is important that all students have access to postsecondary education (PSE). The passage of the Higher Education Opportunity Act has provided students with intellectual disability (ID) a pathway to college, though some barriers in this transition still exist. This article is meant to highlight strategies instructors at the postsecondary level can utilize to support the transition and inclusion of students with ID in college-level courses. The role PSE programs play establishing what college readiness for individuals with ID is also discussed. A specific focus will be paid to how the universal design for learning (UDL) framework can be applied to instructional materials to support the inclusion of students with ID in college, and how these strategies can be modeled for secondary educators to support the transition planning process for students with ID.
L. G. Searle, Landscapes of Accumulation: Real Estate and the Neoliberal Imagination in Contemporary India
Authors: Libeiro Sirus
Published: August 2017

L. G. Searle, Landscapes of Accumulation: Real Estate and the Neoliberal Imagination in Contemporary India. University of Chicago Press, 2016, 313 pages, $27.50, ISBN 978-0-226-38506-8
Ennore, Promises Undelivered: How the Idea of Infinite Growth is Unmaking India
Authors: Singh TejInder , Kumar Pooja , Kuttuva Pradeep
Published: August 2017

The rapid industrialisation and urbanisation in India over the past few decades has resulted in severe environmental destruction and loss of traditional livelihoods, as well as worsened economic and social inequalities. Ennore, a northern suburb of Chennai is a classic example of this phenomenon. This photo essay presents the deleterious impacts of urbanisation on the artisanal fisherfolk of Ennore. The inherently unsustainable nature of water extraction for industries in this region coupled with lax regulations first destroyed the Ennore creek and consequently fisherfolk livelihoods. Dwindling fish catches have created an artificial demand for jobs, thereby resulting in formerly independent communities being completely enslaved to the development paradigm. The state’s response has not been to fix environmental and community health problems in Ennore, but only to push for more growth and development. The essay argues that this toxic idea of growth needs to be dismantled first, if the degradation of livelihood commons is to be stopped.
A slave ants based ant colony optimization algorithm for task scheduling in cloud computing environments
Authors: Moon YoungJu , Yu HeonChang , Gil Joon-Min , Lim JongBeom
Published: August 2017

Since cloud computing provides computing resources on a pay per use basis, a task scheduling algorithm directly affects the cost for users. In this paper, we propose a novel cloud task scheduling algorithm based on ant colony optimization that allocates tasks of cloud users to virtual machines in cloud computing environments in an efficient manner. To enhance the performance of the task scheduler in cloud computing environments with ant colony optimization, we adapt diversification and reinforcement strategies with slave ants. The proposed algorithm solves the global optimization problem with slave ants by avoiding long paths whose pheromones are wrongly accumulated by leading ants.
The Sharpin interactome reveals a role for Sharpin in lamellipodium formation via the Arp2/3 complex
Authors: Khan Meraj H. , Salomaa Siiri I. , Jacquemet Guillaume , Butt Umar , Miihkinen Mitro , Deguchi Takahiro , Kremneva Elena , Lappalainen Pekka , Humphries Martin J. , Pouwels Jeroen
Published: August 2017

Sharpin, a multifunctional adaptor protein, regulates several signalling pathways. For example, Sharpin enhances signal-induced NF-κB signalling as part of the linear ubiquitin assembly complex (LUBAC) and inhibits integrins, the T cell receptor, caspase 1 and PTEN. However, despite recent insights into Sharpin and LUBAC function, a systematic approach to identify the signalling pathways regulated by Sharpin has not been reported. Here, we present the first ‘Sharpin interactome’, which identifies a large number of novel potential Sharpin interactors in addition to several known ones. These data suggest that Sharpin and LUBAC might regulate a larger number of biological processes than previously identified, such as endosomal trafficking, RNA processing, metabolism and cytoskeleton regulation. Importantly, using the Sharpin interactome, we have identified a novel role for Sharpin in lamellipodium formation. We demonstrate that Sharpin interacts with Arp2/3, a protein complex that catalyses actin filament branching. We have identified the Arp2/3-binding site in Sharpin and demonstrate using a specific Arp2/3-binding deficient mutant that the Sharpin–Arp2/3 interaction promotes lamellipodium formation in a LUBAC-independent fashion.

This article has an associated First Person interview with the first author of the paper.
Peroxisomal plant metabolism – an update on nitric oxide, Ca2+ and the NADPH recycling network
Authors: Corpas Francisco J. , Barroso Juan B.
Published: August 2017

Plant peroxisomes are recognized organelles that – with their capacity to generate greater amounts of H2O2 than other subcellular compartments – have a remarkable oxidative metabolism. However, over the last 15 years, new information has shown that plant peroxisomes contain other important molecules and enzymes, including nitric oxide (NO), peroxynitrite, a NADPH-recycling system, Ca2+ and lipid-derived signals, such as jasmonic acid (JA) and nitro-fatty acid (NO2-FA). This highlights the potential for complex interactions within the peroxisomal nitro-oxidative metabolism, which also affects the status of the cell and consequently its physiological processes. In this review, we provide an update on the peroxisomal interactions between all these molecules. Particular emphasis will be placed on the generation of the free-radical NO, which requires the presence of Ca2+, calmodulin and NADPH redox power. Peroxisomes possess several NADPH regeneration mechanisms, such as those mediated by glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) proteins, which are involved in the oxidative phase of the pentose phosphate pathway, as well as that mediated by NADP-isocitrate dehydrogenase (ICDH). The generated NADPH is also an essential cofactor across other peroxisomal pathways, including the antioxidant ascorbate–glutathione cycle and unsaturated fatty acid β-oxidation, the latter being a source of powerful signaling molecules such as JA and NO2-FA.
The requirement of IRE1 and XBP1 in resolving physiological stress during Drosophila development
Authors: Huang Huai-Wei , Zeng Xiaomei , Rhim Taiyoun , Ron David , Ryoo Hyung Don
Published: August 2017

IRE1 mediates the unfolded protein response (UPR) in part by regulating XBP1 mRNA splicing in response to endoplasmic reticulum (ER) stress. In cultured metazoan cells, IRE1 also exhibits XBP1-independent biochemical activities. IRE1 and XBP1 are developmentally essential genes in Drosophila and mammals, but the source of the physiological ER stress and the relative contributions of XBP1 activation versus other IRE1 functions to development remain unknown. Here, we employed Drosophila to address this question. Explicitly, we find that specific regions of the developing alimentary canal, fat body and the male reproductive organ are the sources of physiological stress that require Ire1 and Xbp1 for resolution. In particular, the developmental lethality associated with an Xbp1 null mutation was rescued by transgenic expression of Xbp1 in the alimentary canal. The domains of IRE1 that are involved in detecting unfolded proteins, cleaving RNAs and activating XBP1 splicing were all essential for development. The earlier onset of developmental defects in Ire1 mutant larvae compared to in Xbp1-null flies supports a developmental role for XBP1-independent IRE1 RNase activity, while challenging the importance of RNase-independent effector mechanisms of Drosophila IRE1 function.
Solving Variational Inequalities with Stochastic Mirror-Prox Algorithm
Authors: Juditsky Anatoli , Nemirovski Arkadi , Tauvel Claire
Published: August 2017

In this paper we consider iterative methods for stochastic variational inequalities (s.v.i.) with monotone operators. Our basic assumption is that the operator possesses both smooth and nonsmooth components. Further, only noisy observations of the problem data are available. We develop a novel Stochastic Mirror-Prox (SMP) algorithm for solving s.v.i. and show that with the convenient stepsize strategy it attains the optimal rates of convergence with respect to the problem parameters. We apply the SMP algorithm to Stochastic composite minimization and describe particular applications to Stochastic Semidefinite Feasibility problem and deterministic Eigenvalue minimization.
On the Superposition of Heterogeneous Traffic at Large Time Scales
Authors: López-Oliveros Luis , Resnick Sidney I.
Published: August 2017

Various empirical and theoretical studies indicate that cumulative network traffic is a Gaussian process. However, depending on whether the intensity at which sessions are initiated is large or small relative to the session duration tail, [25] and [15] have shown that traffic at large time scales can be approximated by either fractional Brownian motion (fBm) or stable Lévy motion. We study distributional properties of cumulative traffic that consists of a finite number of independent streams and give an explanation of why Gaussian examples abound in practice but not stable Lévy motion. We offer an explanation of how much vertical aggregation is needed for the Gaussian approximation to hold. Our results are expressed as limit theorems for a sequence of cumulative traffic processes whose session initiation intensities satisfy growth rates similar to those used in [25].
Stability of a Markov-modulated Markov Chain, with Application to a Wireless Network Governed by two Protocols
Authors: Foss Sergey , Shneer Seva , Tyurlikov Andrey
Published: August 2017

We consider a discrete-time Markov chain (Xt,Yt), t = 0, 1, 2,…, where the X-component forms a Markov chain itself. Assume that (Xt) is Harris-ergodic and consider an auxiliary Markov chain [Formula: see text] whose transition probabilities are the averages of transition probabilities of the Y-component of the (X, Y)-chain, where the averaging is weighted by the stationary distribution of the X-component.

We first provide natural conditions in terms of test functions ensuring that the [Formula: see text]-chain is positive recurrent and then prove that these conditions are also sufficient for positive recurrence of the original chain (Xt, Yt). The we prove a “multi-dimensional” extension of the result obtained. In the second part of the paper, we apply our results to two versions of a multi-access wireless model governed by two randomised protocols.
On the Power of (Even a Little) Resource Pooling
Authors: Tsitsiklis John N. , Xu Kuang
Published: August 2017

We propose and analyze a multi-server model that captures a performance trade-off between centralized and distributed processing. In our model, a fraction p of an available resource is deployed in a centralized manner (e.g., to serve a most-loaded station) while the remaining fraction 1 − p is allocated to local servers that can only serve requests addressed specifically to their respective stations.

Using a fluid model approach, we demonstrate a surprising phase transition in the steady-state delay scaling, as p changes: in the limit of a large number of stations, and when any amount of centralization is available (p > 0), the average queue length in steady state scales as [Formula: see text] when the traffic intensity λ goes to 1. This is exponentially smaller than the usual M/M/1-queue delay scaling of [Formula: see text], obtained when all resources are fully allocated to local stations (p = 0). This indicates a strong qualitative impact of even a small degree of resource pooling.

We prove convergence to a fluid limit, and characterize both the transient and steady-state behavior of the actual system, in the limit as the number of stations N goes to infinity. We show that the sequence of queue-length processes converges to a unique fluid trajectory (over any finite time interval, as N → ∞), and that this fluid trajectory converges to a unique invariant state vI, for which a simple closed-form expression is obtained. We also show that the steady-state distribution of the N-server system concentrates on vI as N goes to infinity.
Diffusion Approximation for an Input-queued Switch Operating under a Maximum Weight Matching Policy
Authors: Kang W. N. , Williams R. J.
Published: August 2017

For N ≥ 2, we consider an N × N input-queued switch operating under a maximum weight matching policy. We establish a diffusion approximation for a (2N − 1)-dimensional workload process associated with this switch when all input ports and output ports are heavily loaded. The diffusion process is a semimartingale reflecting Brownian motion living in a polyhedral cone with N2 boundary faces, each of which has an associated constant direction of reflection. Our proof builds on our own prior work [13] on an invariance principle for semimartingale reflecting Brownian motions in piecewise smooth domains and on a multiplicative state space collapse result for switched networks established by Shah and Wischik in [19].
Asymptotics of the Invariant Measure in Mean Field Models with Jumps
Authors: Borkar Vivek S. , Sundaresan Rajesh
Published: August 2017

We consider the asymptotics of the invariant measure for the process of the empirical spatial distribution of N coupled Markov chains in the limit of a large number of chains. Each chain reflects the stochastic evolution of one particle. The chains are coupled through the dependence of the transition rates on this spatial distribution of particles in the various states. Our model is a caricature for medium access interactions in wireless local area networks. It is also applicable to the study of spread of epidemics in a network. The limiting process satisfies a deterministic ordinary differential equation called the McKean-Vlasov equation. When this differential equation has a unique globally asymptotically stable equilibrium, the spatial distribution asymptotically concentrates on this equilibrium. More generally, its limit points are supported on a subset of the ω-limit sets of the McKean-Vlasov equation. Using a control-theoretic approach, we examine the question of large deviations of the invariant measure from this limit.
A Two-dimensional, Two-sided Euler Inversion Algorithm with Computable Error Bounds and its Financial Applications
Authors: Cai Ning , Shi Chao
Published: August 2017

In this paper we propose an inversion algorithm with computable error bounds for two-dimensional, two-sided Laplace transforms. The algorithm consists of two discretization parameters and two truncation parameters. Based on the computable error bounds, we can select these parameters appropriately to achieve any desired accuracy. Hence this algorithm is particularly useful to provide benchmarks. In many cases, the error bounds decay quickly (e.g., exponentially), making the algorithm very efficient. We apply this algorithm to price exotic options such as spread options and barrier options under various asset pricing models as well as to evaluate the joint cumulative distribution functions of related state variables. The numerical examples indicate that the inversion algorithm is accurate, fast and easy to implement.
Large Deviations of the Interference in the Ginibre Network Model
Authors: Torrisi Giovanni Luca , Leonardi Emilio
Published: August 2017

Under different assumptions on the distribution of the fading random variables, we derive large deviation estimates for the tail of the interference in a wireless network model whose nodes are placed, over a bounded region of the plane, according to the β-Ginibre process, 0 < β ≤ 1. The family of β-Ginibre processes is formed by determinantal point processes, with different degree of repulsiveness. As β → 0, β-Ginibre processes converge in law to a homogeneous Poisson process. In this sense the Poisson network model may be considered as the limiting uncorrelated case of the β-Ginibre network model. Our results indicate the existence of two different regimes.

When the fading random variables are bounded or Weibull superexponential, large values of the interference are typically originated by the sum of several equivalent interfering contributions due to nodes in the vicinity of the receiver. In this case, the tail of the interference has, on the log-scale, the same asymptotic behavior for any value of 0 < β ≤ 1, but it differs from the asymptotic behavior of the tail of the interference in the Poisson network model (again on a log-scale) [14].

When the fading random variables are exponential or subexponential, instead, large values of the interference are typically originated by a single dominating interferer node and, on the log-scale, the asymptotic behavior of the tail of the interference is insensitive to the distribution of the nodes, as long as the number of nodes is guaranteed to be light-tailed.
Models with Hidden Regular Variation: Generation and Detection
Authors: Das Bikramjit , Resnick Sidney I.
Published: August 2017

We review the notions of multivariate regular variation (MRV) and hidden regular variation (HRV) for distributions of random vectors and then discuss methods for generating models exhibiting both properties concentrating on the non-negative orthant in dimension two. Furthermore we suggest diagnostic techniques that detect these properties in multivariate data and indicate when models exhibiting both MRV and HRV are plausible fits for the data. We illustrate our techniques on simulated data, as well as two real Internet data sets.
On Patient Flow in Hospitals: A Data-Based Queueing-Science Perspective
Authors: Armony Mor , Israelit Shlomo , Mandelbaum Avishai , Marmor Yariv N. , Tseytlin Yulia , Yom-Tov Galit B.
Published: August 2017

Hospitals are complex systems with essential societal benefits and huge mounting costs. These costs are exacerbated by inefficiencies in hospital processes, which are often manifested by congestion and long delays in patient care. Thus, a queueing-network view of patient flow in hospitals is natural for studying and improving its performance. The goal of our research is to explore patient flow data through the lens of a queueing scientist. The means is exploratory data analysis (EDA) in a large Israeli hospital, which reveals important features that are not readily explainable by existing models.

Questions raised by our EDA include: Can a simple (parsimonious) queueing model usefully capture the complex operational reality of the Emergency Department (ED)? What time scales and operational regimes are relevant for modeling patient length of stay in the Internal Wards (IWs)? How do protocols of patient transfer between the ED and the IWs influence patient delay, workload division and fairness? EDA also underscores the importance of an integrative view of hospital units by, for example, relating ED bottlenecks to IW physician protocols. The significance of such questions and our related findings raise the need for novel queueing models and theory, which we present here as research opportunities.

Hospital data, and specifically patient flow data at the level of the individual patient, is increasingly collected but is typically confidential and/or proprietary. We have been fortunate to partner with a hospital that allowed us to open up its data for everyone to access. This enables reproducibility of our findings, through a user-friendly platform that is accessible via the Technion SEELab.
Convergence Properties of Weighted Particle Islands with Application to the Double Bootstrap Algorithm
Authors: Del Moral Pierre , Moulines Eric , Olsson Jimmy , Vergé Christelle
Published: August 2017

Particle island models [31] provide a means of parallelization of sequential Monte Carlo methods, and in this paper we present novel convergence results for algorithms of this sort. In particular we establish a central limit theorem—as the number of islands and the common size of the islands tend jointly to infinity—of the double bootstrap algorithm with possibly adaptive selection on the island level. For this purpose we introduce a notion of archipelagos of weighted islands and find conditions under which a set of convergence properties are preserved by different operations on such archipelagos. This theory allows arbitrary compositions of these operations to be straightforwardly analyzed, providing a very flexible framework covering the double bootstrap algorithm as a special case. Finally, we establish the long-term numerical stability of the double bootstrap algorithm by bounding its asymptotic variance under weak and easily checked assumptions satisfied typically for models with non-compact state space.
Heavy Traffic Queue Length Behavior in a Switch Under the MaxWeight Algorithm
Authors: Maguluri Siva Theja , Srikant R.
Published: August 2017

We consider a switch operating under the MaxWeight scheduling algorithm, under any traffic pattern such that all the ports are loaded. This system is interesting to study since the queue lengths exhibit a multi-dimensional state-space collapse in the heavy-traffic regime. We use a Lyapunov-type drift technique to characterize the heavy-traffic behavior of the expectation of the sum queue lengths in steady-state, under the assumption that all ports are saturated and all queues receive non-zero traffic. Under these conditions, we show that the heavy-traffic scaled queue length is given by [Formula: see text], where σ is the vector of the standard deviations of arrivals to each port in the heavy-traffic limit. In the special case of uniform Bernoulli arrivals, the corresponding formula is given by [Formula: see text]. The result shows that the heavy-traffic scaled queue length has optimal scaling with respect to n, thus settling one version of an open conjecture; in fact, it is shown that the heavy-traffic queue length is at most within a factor of two from the optimal. We then consider certain asymptotic regimes where the load of the system scales simultaneously with the number of ports. We show that the MaxWeight algorithm has optimal queue length scaling behavior provided that the arrival rate approaches capacity sufficiently fast.
Heavy Traffic Approximation for the Stationary Distribution of a Generalized Jackson Network: The BAR Approach
Authors: Braverman Anton , Dai J. G. , Miyazawa Masakiyo
Published: August 2017

In the seminal paper of Gamarnik and Zeevi [17], the authors justify the steady-state diffusion approximation of a generalized Jackson network (GJN) in heavy traffic. Their approach involves the so-called limit interchange argument, which has since become a popular tool employed by many others who study diffusion approximations. In this paper we illustrate a novel approach by using it to justify the steady-state approximation of a GJN in heavy traffic. Our approach involves working directly with the basic adjoint relationship (BAR), an integral equation that characterizes the stationary distribution of a Markov process. As we will show, the BAR approach is a more natural choice than the limit interchange approach for justifying steady-state approximations, and can potentially be applied to the study of other stochastic processing networks such as multiclass queueing networks.
A Sociocognitive View of Repeated Interfirm Exchanges: How the Coevolution of Trust and Learning Impacts Subsequent Contracts
Authors: Weber Libby
Published: August 2017

I augment the study of repeated interfirm exchanges with social cognition to expand the understanding of trust development and learning and how these combined forces shape subsequent contracts. Although scholars have extensively examined the independent effects of trust and learning on contracts in repeated exchanges, their coevolution and combined impact have received much less attention. I argue this omission occurs largely because social cognition is not typically considered in these literatures, even though both trust development and learning are sociocognitive processes influenced by each other, as well as by heuristics (contract frames) and cognitive biases (intergroup attribution bias). When these processes are examined in a positive exchange, the contract frame (prevention or promotion) influences initial reputation-based trust or prior development of knowledge-based trust (competence or integrity), which biases what is learned. This biased learning further impacts knowledge-based trust development, and together these factors shape adjustments to subsequent contracts. In a negative exchange, the contract frame, prior reputation-based trust, and partner explanation (internal versus external) impact what is learned from partner violations (competence or integrity). This biased learning influences knowledge-based trust development, and together they shape how subsequent contracts are adjusted. I also propose that biased learning influences when contracts act as complements or substitutes for different types of trust, addressing existing debates and critiques in these literatures. Finally, I discuss the dark side of integrity trust and trust repair under promotion contracts in repeated exchanges.
Doing family in the age of involved fatherhood: fathers’ accounts of everyday life in a German context
Authors: Jentsch Birgit , Schier Michaela
Published: August 2017

Qualitative interviews with men, who considered themselves to be ‘active fathers’, explored how they and their partners ‘do family’, particularly with regards to dividing childcare and chores, and awarding the right to self-care. Rationales, motivations and principles of the distribution of parental duties and rights in the context of everyday life were examined. While pragmatic solutions to familial challenges prevailed, normative approaches also featured, for example, regarding fathers’ desire to support their partner's career. Furthermore, the research explored interviewees’ notions of active fatherhood. It revealed that fathers reacted with different approaches to conflicting demands on them (employer versus family). They adopted flexible interpretations of involved fatherhood in order to meet their aspirations of being an active parent.
Singles’ activities: sociability and the ambiguities of singledom
Authors: Henriksson Andreas
Published: August 2017

As the proportion of singles grows in Sweden, the number of commercial and non-commercial activities catering to singles has increased. This article argues that these activities are situating singles within relations to others and to a community, and are becoming sites for performing and negotiating singledom. Using Simmel's concept of sociability, the article presents an analysis of two cases of singles’ activities in Sweden — a company arranging singles’ cruises and festivals, and a singles’ association. It argues that while the organisers talked about singles’ needs for therapeutic social contact, participants themselves sometimes used the activities differently. Rather than understanding themselves as in need of proxy social interaction, they either intended to find a mate, or found actual satisfaction in a community of singles that superseded the need for a partner. Apart from stressing the importance of sociability in understanding singles’ activities, the article shows that this latter conception also challenges normative notions of coupledom, for example, by allowing for singles with partners.
The technological system 2.0: Suggested amendments and revisions under digital assumptions
Authors: Schuchardt Read Mercer
Published: August 2017

When Jacques Ellul wrote Technological System in 1980, he understood it as an update to his earlier observations. By and large, these updates were analogous to the metastasizing of cancer cells; what Ellul saw was that there was ‘more’ technology everywhere, yet its assumptions were largely dependent on the nature of technologies he had analysed in his earlier work, The Technological Society in 1954. In this article, I update the previous insights of Ellul to take into account the critical mass of Internet and cell phone technologies. The ‘digital technological system’ has several more defining characteristics that need to be incorporated in order to fully assess and comprehend the technological system through Ellul’s original lens. By demonstrating that now too ‘that stage has passed’, this article nevertheless shows a continuity with Ellul’s thought in demonstrating that the digital technological system still contains the previous characteristics of autonomy, unity, universality and totalization but that the new digital stage also adds the characteristics of ubiquity, atemporality and disincarnation. What problems this presents for ‘man’ in the digital technological system is the key concern of the resulting analysis.
Jacques Ellul’s contributions to media literacy: Examining The Technological Bluff
Authors: Forsberg Geraldine E.
Published: August 2017

This article examines some of the rhetorical bluffs identified by Jacques Ellul in his book The Technological Bluff. The author explores how understanding the rhetoric about media and technology can contribute to teaching media literacy. Often the focus in education is on a critique of specific media and technologies. Ellul focuses our attention on the rhetoric about technology. This is a unique and important approach to media literacy.
Self and the city: Teaching sensory perception and integration in City as Classroom
Authors: McLeod Rogers Jaqueline
Published: August 2017

City as Classroom – a text McLuhan co-authored with Eric McLuhan and Kathryn Hutchon in 1977 – takes as its chief goal educating readers to identify ‘[p]atterns and structures [that] “make sense” of things’ (McLuhan et al. 1977: 165), presenting readers with a pedagogical model for exercising and attempting to balance their multiple senses. The text is directed in particular at a youthful audience, those who have inherited a technologized world but no critical tools for understanding or managing it. McLuhan invites readers to explore a process of knowing meant to reactivate human capacities turned off by a succession of takeover technologies. He reveals to readers/practitioners the power of the senses to capture rich perceptual information, engaging them in reshaping both how they know the environment and what they know of it. Offering non-mainstream pedagogical concepts and libratory learning practices and outcomes, this text speaks to the needs of contemporary students and readers.
The four ecologies, post-evolution and singularity
Authors: Zhang Peter
Published: August 2017

This article responds to the imminent break boundary humanity is facing from the vantage point of the productive interface between media ecology and French thought, especially that of Deleuze, Guattari and Virilio. It extends Guattari’s work by putting forward the notion of the four ecologies, reveals the post-evolutionary nature of our era and promotes spiritual singularity, as distinguished from technological singularity, as a phronētic way of pursuing the good life at this historical juncture. The article belongs to the emerging body of literature on interology. A Zen sensibility runs through the entire article.
Hacia una nueva concepción epistemológica de la metodología científica- Towards a new epistemological conception of scientific methodology
Authors: Gallego Torres Adriana Patricia , Millán-Rojas Edwin Eduardo
Published: August 2017

Editorial
Hacia la construcción de un modelo predictivo de deserción académica basado en técnicas de minería de datos - Towards the construction of a predictive model of academic desertion based on data mining techniques
Authors: Sotomonte-Castro Jonny Esteban , Rodríguez-Rodríguez Cristian Camilo , Montenegro-Marín Carlos Enrique , Gaona-García Paulo Alonso , Castellanos John Gabriel
Published: August 2017

Existe un problema latente en la educación de nivel superior en Colombia, el cual tiene que ver con los altos índices de deserción académica, adicionalmente son muy pocas las estrategias que se han implementado con el fin de frenar la tasa de deserción, puesto que solo hasta el año 2003, se inician de manera formal los estudios para poder establecer cuáles son las condiciones que propician el abandono de los estudios. Sin embargo, se desconocen las causas que conllevan a que un estudiante abandone su carrera, para ello en este artículo se hará uso de la Minería de Datos, por medio de la cual se pretende generar un modelo de Árbol de Decisión implementando el algoritmo J48 mediante el uso de la herramienta WEKA con el fin de poder identificar estas causas.
EL PAPEL DE LA OBSERVACIÓN EN LA FORMALIZACIÓN DE CONCEPTOS A PARTIR DE LA CONTRIBUCIÓN DE LA ASTRONOMÍA. CASO PARTICULAR: NUESTRA ESTRELLA EL SOL
Authors: Arias Marlón , Huerfano Andrea
Published: August 2017

Este trabajo presenta una estrategia pedagógica para el desarrollo de la observación como método de investigación en estudiantes de básica primaria, con el fin de promover la comprensión de fenómenos físicos, a partir de la exploración de las características básicas del Sol. Su objetivo principal es potencializar los dispositivos básicos de aprendizaje en estudiantes de primaria, a partir del desarrollo de actividades que promuevan un adecuado desenvolvimiento de los niños dentro y fuera del entorno escolar. Se busca trabajar a partir del reconocimiento y la constante observación de ideas en torno al sol que han construido los estudiantes e introducir relaciones que posibiliten un dialogo desequilibrante entre maestro-estudiante y estudiante-estudiante sobre fenómenos relacionados al sol como lo son: las sombras, porque hay día y noche, la apariencia y composición del sol, entre otras. Al mismo tiempo, posibilitar la incorporación de material de trabajo de las ciencias físicas básicas, junto con actividades artísticas que apoyen el desarrollo del razonamiento espacial y lógico, en búsqueda de estimular a los estudiantes hacia el conocimiento de elementos en astronomía y que ellos logren dar razón de fenómenos que suceden a su alrededor y encontrar respuestas de sucesos que se den en su quehacer cotidiano.
EMPLEO DE GRÁFICAS EN EL ESTUDIO DEL CONCEPTO DE ELASTICIDAD EN EL SISTEMA ÓSEO: EXPERIENCIA EN UN CURSO DE MECÁNICA EN LA CARRERA DE MEDICINA
Authors: Marín-Santamaría Y.C. , Puentes-Ossa A.M.
Published: August 2017

La enseñanza de la física en las ciencias biomédicas y concretamente en medicina implica crear nuevas metodologías que permitan al estudiante comprender los conceptos, las leyes y las teorías científicas, desde su formación como médicos, lo que contribuirá al empleo de los conceptos aprendidos durante su desempeño profesional. En ese orden de ideas, con el objetivo de contribuir a la comprensión del concepto de elasticidad en el estudio de la biomecánica del hueso se diseñó e implementó, a partir de gráficas de esfuerzo y deformación de huesos sometidos a diferentes tipos de cargas, una unidad didáctica para el estudio de la ley de Hooke y el modulo de Young en el curso de mecánica en la carrera de medicina. Al final de la implementación de la unidad didáctica se aplicó una prueba en contexto donde se evaluaron conceptos aprendidos y habilidades de los estudiantes en la interpretación de gráficas; esto se realizó a partir de gráficas de esfuerzo y deformaciónde huesos, resultado de investigaciones en pacientes de distintas edades, sometidos a diferentes tipos de cargas (Nordin & Frankel, 2001). En este artículo presentamos la propuesta metodológica y los resultados de su implementación.
PROPUESTA ETNOEDUCATIVA: LA FORMACIÓN DEL MUNDO DESDE DOS PERSPECTIVAS DIFERENTES
Authors: Callejas Arévalo Ronal Enrique , Rueda Velasco Yeni Milena , Salazar Garzón Franceidy Andrea
Published: August 2017

La Constitución Colombiana es clara afirmando que la educación es un servicio y un derecho que debe ser impartida a todas las culturas por igual, reconociendo el carácter pluriétnico y multicultural del país. Con base en esta aseveración el presente trabajo tiene como objetivo reconocer la cosmovisión de los integrantes del Cabildo Muisca de Bosaacerca de la formación del mundo, contrastándola frente a la representación física de este evento. Para tal reconocimiento de saberes, se plantea una estrategia didáctica que de manera respetuosa y atenta muestra la cosmovisión del pueblo muisca y la representación física de la formación del mundo. La estrategia didáctica presenta un cuento interactivo, dirigido a niños integrantes del cabildo muisca cuyas edades oscilan entre los 7 y 9 años. La estrategia didáctica, consta de tres fases reflejadas en el cuento, las cuales llevan por nombre: ¿Qué tanto sabemos?, reconozcamos dos saberes y reflexionemos; cada una de estas fases cuenta con un grupo de actividades de interacción con el lector, buscando generar una actitud activa durante la ejecución de laestrategia.
PROPUESTA PEDAGÓGICA EN TORNO A TÓPICOS INTRODUCTORIOS DE FÍSICA NUCLEAR
Authors: Ramos G. E. P. , Peralta M. J. J. , Monroy C. I. A. , Cardona R. G.
Published: August 2017

Investigaciones en el área de la enseñanza de la física en el ámbito escolar han demostrado una gran tendencia en diferentes países a proponer nuevos objetivos dentro de ésta, entre los cuales además se encuentra el reconocimiento y descripción de conceptos introductorios de física moderna en la secundaria, para nuestro caso de interés en particular la enseñanza de la física nuclear. Por otra parte, la forma como son abordadas muchas de las temáticas involucradas no suponen una metodología eficiente, lo que plantea la necesidad de un nuevo enfoque a la hora de abordar éste tipo de tópicos en la escuela, para así optimizar la enseñanza de estos. Se proponen diferentes actividades desde la metodología del aprendizaje cooperativo-colaborativo con el fin deabordar la enseñanza de temas introductorios de física nuclear (estructura atómica y fusión nuclear); en donde estos son afrontados a partir de experiencias en el aula que simulen los fenómenos que están ligados a las diferentes temáticas. Anexo a las actividades se incluyeron animaciones para respaldar el material empleado en el aula.
INCONVENIENTES CON LA TECNOLOGÍA EN LA ENSEÑANZA DE LA FÍSICA
Authors: Orjuela Abril Juan Carlos
Published: August 2017

El problema social en el que vivimos, nos muestra una serie de deficiencias en el ámbito de la educación de los jóvenes, bien sea en el hogar, en el colegio, en el trabajo, o en su entorno social (amigos). La drogadicción, el alcohol, el maltrato, la televisión, los videojuegos, la moda, son condiciones sociales a las cuales los jóvenes están expuestos en su diario vivir, y por ende, estas influencias toman posesión en el proyecto de vida de los jóvenes, y no desarrollan su pensamiento en cosas que no ayudaran en su vida futura sino que por el contrario se podría estar perdiendo conocimiento en nuestra civilización, yes allí donde los docentes entran a actuar.