bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-term efficacy of fractionated conformal radiotherapy for the management of primary optic nerve sheath meningioma
Authors: Pandit Ravi , Paris Liliana , Rudich Danielle S , Lesser Robert L , Kupersmith Mark J , Miller Neil R
Published: December 2018

Background/Aim

Fractionated conformal radiotherapy (FCRT) is now used to treat vision-threatening optic nerve sheath meningioma (ONSM), but long-term efficacy and safety data are lacking; the purpose of this study was to assess these key data.

Methods

This is a retrospective chart review with prospective follow-up of adult patients treated with FCRT for primary ONSM at four academic medical centres between 1995 and 2007 with ≥10 years of follow-up after treatment.

Results

16 patients were identified with a mean post-treatment follow-up of 14.6 years (range: 10.5–20.7 years). The mean age at symptom onset was 47.6 years (range: 36–60 years). FCRT was performed at a mean of 2.3 years after symptom onset (range: 0.2–14.0 years). At last follow-up, visual acuity had improved or stabilised in 14 of the 16 (88%) patients, and 11 (69%) had retained or achieved ≥20/40. The mean deviation on automated perimetry remained stable (−14.5 dB pretreatment vs −12.2 dB at last follow-up; p=0.68, n=10). Two (11%) patients had persistent pain, proptosis or diplopia, compared with six (38%) pretreatment (p=0.11). Two (13%) patients developed radiation retinopathy more than 6 months after completion of therapy, one (50%) of whom had worse visual acuity compared with pretreatment. No patient developed tumour involvement or radiation damage in the fellow eye.

Conclusion

FCRT stabilises or improves visual function in patients with primary ONSM and is associated with a low risk of significant ocular sequelae. This treatment should be considered instead of surgery in patients with primary ONSM who require intervention due to loss of visual sensory and/or ocular motor function.
The effectiveness and cost-effectiveness of a complex community sport intervention to increase physical activity: an interrupted time series design
Authors: Anokye Nana , Mansfield Louise , Kay Tess , Sanghera Sabina , Lewin Alex , Fox-Rushby Julia
Published: December 2018

Objectives

An effectiveness and cost-effectiveness analyses of two-staged community sports interventions; taster sports sessions compared with portfolio of community sport sessions.

Design

Quasi-experiment using an interrupted time series design.

Setting

Community sports projects delivered by eight lead partners in London Borough of Hounslow, UK.

Participants

Inactive people aged 14 plus years (n=246) were recruited between May 2013 and February 2014.

Interventions

Community sports interventions delivered in two stages, 6-week programme of taster sport sessions (stage 1) and 6-week programme of portfolio of community sporting sessions delivered by trained coaches (stage 2).

Outcome measures

(a) Change in days with ≥30 min of self-reported vigorous intensity physical activity (PA), moderate intensity PA, walking and sport; and (b) change in subjective well-being and EQ5D5L quality-adjusted life-years (QALYs).

Methods

Interrupted time series analysis evaluated the effectiveness of the two-staged sports programmes. Cost-effectiveness analysis compares stage 2 with stage 1 from a provider’s perspective, reporting outcomes of incremental cost per QALY (2015/2016 price year). Uncertainty was assessed using deterministic and probabilistic sensitivity analyses.

Results

Compared with stage 1, counterfactual change at 21 days in PA was lower for vigorous (log odds: −0.52; 95% CI −1 to –0.03), moderate PA (−0.50; 95% CI 0.94 to 0.05) and sport

(−0.56; 95% CI −1.02 to –0.10). Stage 2 increased walking (0.28; 95% CI 0.3 to 0.52). Effect overtime was similar. Counterfactual change at 21 days in well-being was positive particularly for ‘happiness’ (0.29; 95% CI 0.06 to 0.51). Stage 2 was more expensive (£101 per participant) but increased QALYs (0.001; 95% CI −0.034 to 0.036). Cost per QALY for stage 2 was £50 000 and has 29% chance of being cost-effective (£30 000 threshold).

Conclusion

Community-based sport interventions could increase PA among inactive people. Less intensive sports sessions may be more effective and cost-effective.
Biallelic mutations in USP45, encoding a deubiquitinating enzyme, are associated with Leber congenital amaurosis
Authors: Yi Zhen , Ouyang Jiamin , Sun Wenmin , Xiao Xueshan , Li Shiqiang , Jia Xiaoyun , Wang Panfeng , Zhang Qingjiong
Published: December 2018

Background

Leber congenital amaurosis (LCA) is the earliest and most severe form of inherited retinal dystrophies. In approximately 56% of Chinese probands, genetic defects can be detected in known LCA-causing genes. In this study, the objective was to identify pathogenic variants in two unsolved Chinese families with LCA.

Methods

To identify the genetic defect, whole-exome sequencing (WES) and clinical analysis was performed in both probands with LCA as well as in 3011 in-house controls with other hereditary eye diseases. The expression profiles, as well as the phenotype analysis of knockdown zebrafish model and knockout mice model, were performed to investigate the function of USP45 in photoreceptors.

Results

By analysing WES data based on allele frequencies of in-house controls, population allele frequencies and in silico prediction tools, two rare homozygous mutations in USP45 were identified in two unrelated families. Immunohistochemistry of USP45 in the human and zebrafish retinal sections revealed enriched expression in the inner segments of photoreceptors. The knockdown of usp45 transcript in zebrafish led to abnormal retinal development with effects on photoreceptors, which could be successfully rescued by wild-type usp45 mRNA. Moreover, targeted knockout of Usp45 in mice caused abnormal electroretinography responses, similar to that seen in patients with LCA.

Conclusions

Our study implicates that biallelic mutations in USP45 are associated with the occurrence of LCA. Moreover, our results indicate that USP45 is indispensable to the maintenance of photoreceptor function.
Information and advice for veterinary graduates
Authors: McGhee Alexander
Published: December 2018

Reviewed by Max Foreman, a general practitioner with an interest in exotic species.
Hamish Hastie
Authors: Johnston Norman
Published: December 2018

A practitioner with many interests, he was a determined and self‐motivated person who was also incredibly kind and would help people in whatever way he could.
Resistance training with interval blood flow restriction effectively enhances intramuscular metabolic stress with less ischemic duration and discomfort
Authors: Okita Koichi , Takada Shingo , Morita Noriteru , Takahashi Masashige , Hirabayashi Kagami , Yokota Takashi , Kinugawa Shintaro
Published: December 2018

Increases in muscle size and strength similar to those obtained with high resistance load can be achieved by combining lower loads with continuous blood flow restriction (BFR). However, high ratings for distress have been reported for continuous BFR. Therefore, we investigated the efficacy (metabolic stress) of BFR applied only during intervals in resistance exercise. Seven healthy men performed three 1-min sets of plantar flexion (30 reps/min) with 1-min rest intervals under 4 conditions: low-load resistance exercise (L, 20% 1-repetition maximum (1RM)) without BFR (L-noBFR), L with BFR during exercise sets (L-exBFR), L with BFR during rest intervals (L-intBFR), and L with continuous BFR during both exercise and rest intervals (L-conBFR). Based on the results of the first experiment, we performed additional protocols using a moderate load (M, 40% 1RM) with intermittent (exercise or rest intervals) BFR (M-exBFR and M-intBFR). Intramuscular metabolic stress, defined as decreases in phosphocreatine and intramuscular pH, was evaluated by 31P magnetic resonance spectroscopy. Rated perceived exertion (RPE) was also assessed. At the end of exercise, total decreases in phosphocreatine and intramuscular pH were similar among L-noBFR, L-intBFR, and L-exBFR and significantly less than those in L-conBFR (p < 0.05). In contrast, changes in these variables in M-intBFR but not in M-exBFR were similar to those in L-conBFR. Nevertheless, RPE was lower in M-intBFR than in both M-exBFR and L-conBFR (p < 0.05). The effect of intermittent BFR during exercise might be insufficient to induce metabolic stress when using a low load. However, effective metabolic stress for muscle adaptation could be obtained by moderate-load resistance exercise with BFR during intervals with less ischemic duration and discomfort.
The effects of anisotropy on the simplest non-minimal coupling between curvature and matter in f(R, T) gravity
Authors: Hossienkhani H. , Yousefi H. , Azimi N.
Published: December 2018

We study anisotropic universe in the f(R, T) modified theories of gravity in the presence of a simplest non-minimal coupling between matter and geometry. We obtain the cosmological implications of this model, as well as the equations of state and the deceleration parameters, which follow from the covariant divergence of the stress–energy tensor. We discuss energy conditions in f(R, T) gravity for an anisotropic universe with an effective matter energy–momentum tensor. It is found that the energy conditions are satisfied for the parameter range considered. We also do a numerical calculation of the model to investigate the behavior of the anisotropy on the evolution of the universe in the f(R, T) cosmology. We find out that the anisotropy can decrease to the order [Formula: see text] at the present time.
Photodetachment of Au− ion confined in a quantum well
Authors: Wang De-hua , Shi Tong , Sun Xin-yue
Published: December 2018

We investigate the single-channel photodetachment dynamics of a non-hydrogenic negative ion confined in a quantum well for the first time. We choose an Au− ion as an example and put forward an analytical formula for the photodetachment cross section using both the quantum mechanical method and the semiclassical closed-orbit theory. It is found that the photodetachment cross section of an Au− ion in a quantum well can be written as a smooth background term multiplied by a modulation factor. The calculation results suggest that multi-periodic oscillatory structures appear in the photodetachment cross section, and the oscillating pattern depends heavily on the position of the ion in the quantum well and the laser light polarization. We compare the results calculated using the quantum mechanical method and the closed-orbit theory, and find good agreement between the two results. The photodetachment cross section formula we put forward is universal, and can be applied to any negative ion with a p-wave photodetachment. On account of its general applicability, our work can provide some guidance for the experimental study of the photodetachment processes of non-hydrogenic negative ions in the presence of a quantum well or a microcavity.
A method for dynamic modeling and simulation of the translational joint with clearance and LuGre friction
Authors: Wang Xiaojun
Published: December 2018

The main purpose of this paper is to present a method for dynamic modeling and simulation of the translational joint with friction and clearance. The sizes of the clearances and the impacts between the slider and the guide in the translational joint can be neglected when the clearance sizes are very small. The geometric constraints of the translational joint are treated as bilateral constraints. The contact forces acting on the slider are reduced to the forces on the slider corners. The LuGre friction model is used to describe friction between slider and guide, because it can capture the variation of the friction force with slip velocity and the slider motion with stick–slip phenomenon. The problem of computing the normal forces on the slider is formulated and solved as a horizontal linear complementarity problem (HLCP), which is embedded in the event-driven method. Finally, a numerical example is considered and numerical results are presented to show the feasibility and the effectiveness of the method.
A Reinforcement Learning Approach for Solving the Mean Variance Customer Portfolio in Partially Observable Models
Authors: Asiain Erick , Clempner Julio B. , Poznyak Alexander S.
Published: December 2018

In problems involving control of financial processes, it is usually complicated to quantify exactly the state variables. It could be expensive to acquire the exact value of a given state, even if it may be physically possible to do so. In such cases it may be interesting to support the decision-making process on inaccurate information pertaining to the system state. In addition, for modeling real-world application, it is necessary to compute the values of the parameters of the environment (transition probabilities and observation probabilities) and the reward functions, which are typically, hand-tuned by experts in the field until it has acquired a satisfactory value. This results in an undesired process.

To address these shortcomings, this paper provides a new Reinforcement Learning (RL) framework for computing the mean-variance customer portfolio with transaction costs in controllable Partially Observable Markov Decision Processes (POMDPs). The solution is restricted to finite state, action, observation sets and average reward problems. For solving this problem, a controller/actor-critic architecture is proposed, which balance the difficult tasks of exploitation and exploration of the environment. The architecture consists of three modules: controller, fast-tracked portfolio learning and an actor-critic module. Each module involves the design of a convergent Temporal Difference (TD) learning algorithm. We employ three different learning rules to estimate the real values of: (a) the transition matrices [Formula: see text], (b) the rewards [Formula: see text] and (c) the resources destined for carrying out a promotion [Formula: see text]. We present a proof for the estimated transition matrix rule [Formula: see text] and showing that it converges when t → ∞. For solving the optimization programming problem we extend the c-variable method for partially observable Markov chains. The c-variable is conceptualized as joint strategy given by the product of the control policy, the observation kernel Q(y|s) and the stationary distribution vector. A major advantage of this procedure is that it can be implemented efficiently for real settings in controllable POMDP. A numerical example illustrates the results of the proposed method.
Complete solutions of the simultaneous Pell’s equations x2 − (a2 − 1)y2 = 1 and y2 − pz2 = 1
Authors: Yang Hai , Fu Ruiqin
Published: December 2018

Let [Formula: see text] be a positive integer with [Formula: see text], and let [Formula: see text] be an odd prime. In this paper, by using certain properties of Pell’s equations and quartic diophantine equations with some elementary methods, we prove that the system of equations [Formula: see text] [Formula: see text] and [Formula: see text] has positive integer solutions [Formula: see text] if and only if [Formula: see text] and [Formula: see text] satisfy [Formula: see text] and [Formula: see text], where [Formula: see text], [Formula: see text] and [Formula: see text] are positive integers. Further, if the above condition is satisfied, then [Formula: see text] has only the positive integer solution [Formula: see text]. By the above result, we can obtain the following corollaries immediately. (i) If [Formula: see text] or [Formula: see text], then [Formula: see text] has no positive integer solutions [Formula: see text]. (ii) For [Formula: see text], [Formula: see text] has only the positive integer solutions [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text].
Galois groups of Taylor polynomials of some elementary functions
Authors: Shokri Khosro Monsef , Shaffaf Jafar , Taleb Reza
Published: December 2018

Motivated by Schur’s result on computing the Galois groups of the exponential Taylor polynomials, this paper aims to compute the Galois groups of the Taylor polynomials of the elementary functions [Formula: see text] and [Formula: see text]. We first show that the Galois groups of the [Formula: see text]th Taylor polynomials of [Formula: see text] are as large as possible, namely, [Formula: see text] (full symmetric group) or [Formula: see text] (alternating group), depending on the residue of the integer number [Formula: see text] modulo [Formula: see text]. We then compute the Galois groups of the [Formula: see text]th Taylor polynomials of [Formula: see text] and show that these Galois groups essentially coincide with the Coexter groups of type [Formula: see text] (or an index 2 subgroup of the corresponding Coexter group).
Congruences modulo powers of 2 for generalized Frobenius partitions with six colors
Authors: Cui Su-Ping , Gu Nancy S. S.
Published: December 2018

A generalized Frobenius partition of [Formula: see text] with [Formula: see text] colors is a two-rowed array [Formula: see text] where [Formula: see text], and the integer entries are taken from [Formula: see text] distinct copies of the non-negative integers distinguished by color, and the rows are ordered first by size and then by color with no two consecutive like entries in any row. Let [Formula: see text] denote the number of this kind of partitions of [Formula: see text] with [Formula: see text] colors. In this paper, we establish some congruences modulo powers of 2 for [Formula: see text].
Upper bounds on the second largest prime factor of an odd perfect number
Authors: Zelinsky Joshua
Published: December 2018

Acquaah and Konyagin showed that if [Formula: see text] is an odd perfect number with prime factorization [Formula: see text], where [Formula: see text], then one must have [Formula: see text]. Using methods similar to theirs, we show that [Formula: see text] and that [Formula: see text] We also show that if [Formula: see text] and [Formula: see text] are close to each other, then these bounds can be further strengthened.
Structural and functional studies of erythrocyte membrane-skeleton by single-cell and single-molecule techniques
Authors: Xing Fulin , Hu Fen , Yang Jianyu , Pan Leiting , Xu Jingjun
Published: December 2018

As the indispensable oxygen-transporting cells, erythrocytes exhibit extreme deformability and amazing stability as they are subject to huge reversible shear stress and extrusion force during massive circulation in the body. The unique architecture of spectrin-actin-based membrane-skeleton is considered to be responsible for such excellent mechanical properties of erythrocytes. Although erythrocytes have been recognized for more than 300 years, myriad questions about membrane-skeleton constantly attract people’s attention. Here, we summarize the kinds of distinctive single-cell and single-molecule techniques that were used to investigate the structure and function of erythrocyte membrane-skeleton at macro and micro levels.
Aggregate supply in Hong Kong: past, present and looking to the future
Authors: Millis Stuart , Chan Kitty , Wallace Mark
Published: December 2018

Hong Kong is one of the most densely developed and populated places on the planet, with a population density of just under 7000 people per km
2
and over 300 buildings with heights greater than 150 m, more than 90% of which used concrete as their main structural material. The nature and scale of this development means that aggregates from local hard rock quarries have formed an essential construction material for the development of the territory. However, the small area of Hong Kong (1104 km
2
), its lack of readily developable land and increasing public concern on the impact of quarrying have led to the rehabilitation and closure of most local quarry sites over the last 20 years. The decline in local aggregate supply caused by this has resulted in an increasing reliance on aggregate imported from elsewhere, with associated implications in terms of supply, cost and quality control. Quarry closure has also reduced Hong Kong's readiness to process and reuse good-quality rock generated by construction projects. To combat these issues, a detailed review of the short- and long-term aggregate supply strategies for Hong Kong was conducted, including a territory-wide search for potential new quarry sites together with assessments of the feasibility of integrating other aggregate sources in the supply chain such as underground quarrying and the use of recycled aggregate.
Intelligent systems for geosciences
Authors: Gil Yolanda , Pierce Suzanne A. , Babaie Hassan , Banerjee Arindam , Borne Kirk , Bust Gary , Cheatham Michelle , Ebert-Uphoff Imme , Gomes Carla , Hill Mary , Horel John , Hsu Leslie , Kinter Jim , Knoblock Craig , Krum David , Kumar Vipin , Lermusiaux Pierre , Liu Yan , North Chris , Pankratius Victor , Peters Shanan , Plale Beth , Pope Allen , Ravela Sai , Restrepo Juan , Ridley Aaron , Samet Hanan , Shekhar Shashi , Skinner Katie , Smyth Padhraic , Tikoff Basil , Yarmey Lynn , Zhang Jia
Published: December 2018

A research agenda for intelligent systems that will result in fundamental new capabilities for understanding the Earth system.
Autonomous tools and design
Authors: Seidel Stefan , Berente Nicholas , Lindberg Aron , Lyytinen Kalle , Nickerson Jeffrey V.
Published: December 2018

In addition to having a detailed understanding of the artifacts they intend to create, designers need to guide the software tools they use.
Computer-Assisted Orientation and Drawing of Archaeological Pottery
Authors: Wilczek Josef , Monna Fabrice , Jébrane Ahmed , Chazal Catherine Labruère , Navarro Nicolas , Couette Sébastien , Smith Carmela Chateau
Published: December 2018

Archaeologists spend considerable time orienting and drawing ceramic fragments by hand for documentation, to infer their manufacture, the nature of the discovery site and its chronology, and to develop hypotheses about commercial and cultural exchanges, social organisation, resource exploitation, and taphonomic processes. This study presents a survey of existing solutions to the time-consuming problem of orienting and drawing pottery fragments. Orientation is based on the 3D geometry of pottery models, which can now be acquired in minutes with low-cost 3D scanners. Several methods are presented: they are based on normal vectors, or circle fittings, or profile fittings. All these methods seek to determine the optimal position of the rotation axis. We also present and discuss new approaches and improvements to existing methods. We have developed a suite of functions for the computer-assisted orientation and drawing of archaeological pottery. The profile and contours of the fragment, as well as any possible decoration, can be depicted in various ways: photorealistic rendering or dotted patterns, calculated by ambient occlusion, combined or not with artificial light. The general workflow, evaluated using both synthetic and real-world fragments, is rapid, accurate, and reproducible. It drastically reduces the amount of routine work required to document ceramic artefacts. The information produced, together with the 3D representation of the fragments, can easily be archived and/or exchanged within the archaeological community for further research. The source code (built in the R environment), together with an installation notice and examples, is freely downloadable.
Augmented Experiences in Cultural Spaces through Social Participation
Authors: Díaz Paloma , Bellucci Andrea , Yuan Chien-Wen , Aedo Ignacio
Published: December 2018

Technologies such as the Internet of Things (IoT) and Social Computing offer promising opportunities to envision and shape augmented experiences in a wide variety of cultural spaces. Such interactive technologies act as a hook to attract visitor's attention, but if they do not provide opportunities to engage people in a more personal and meaningful way, they can be soon discarded. Augmented experiences need to be motivating and connect with values and expectations of visitors and institutions. In a world that is becoming more and more connected and moving towards a participatory culture, the need to participate actively to co-produce knowledge and meaning can be exploited as a powerful intrinsic motivator. In this article, we describe how the Social Display Environment (SDE) promotes participation in cultural spaces whilst keeping the physical connection with the exhibition objects. The SDE makes use of Augmented Reality (AR) technology to augment physical artifacts in an exhibition with overlays of digital information that is generated by the end user (e.g., the visitor). The prototype was exhibited in a cultural center over a weekend to investigate different dynamics in terms of content generation, visitors’ interactions and perceptions with respect to the interplay of digital information and physical artifacts. The prototype was assessed as easy to learn and useful and showed potential to promote a number of meaningful social interactions around the objects involved in the exhibition.
Modeling in engineering and science
Authors: Lee Edward A.
Published: December 2018

Understanding behavior by building models.
Optimizing CNN-based Segmentation with Deeply Customized Convolutional and Deconvolutional Architectures on FPGA
Authors: Liu Shuanglong , Fan Hongxiang , Niu Xinyu , Ng Ho-cheung , Chu Yang , LUK Wayne
Published: December 2018

Convolutional Neural Networks-- (CNNs) based algorithms have been successful in solving image recognition problems, showing very large accuracy improvement. In recent years, deconvolution layers are widely used as key components in the state-of-the-art CNNs for end-to-end training and models to support tasks such as image segmentation and super resolution. However, the deconvolution algorithms are computationally intensive, which limits their applicability to real-time applications. Particularly, there has been little research on the efficient implementations of deconvolution algorithms on FPGA platforms that have been widely used to accelerate CNN algorithms by practitioners and researchers due to their high performance and power efficiency. In this work, we propose and develop deconvolution architecture for efficient FPGA implementation. FPGA-based accelerators are proposed for both deconvolution and CNN algorithms. Besides, memory sharing between the computation modules is proposed for the FPGA-based CNN accelerator as well as for other optimization techniques. A non-linear optimization model based on the performance model is introduced to efficiently explore the design space to achieve optimal processing speed of the system and improve power efficiency. Furthermore, a hardware mapping framework is developed to automatically generate the low-latency hardware design for any given CNN model on the target device. Finally, we implement our designs on Xilinx Zynq ZC706 board and the deconvolution accelerator achieves a performance of 90.1 giga operations per second (GOPS) under 200MHz working frequency and a performance density of 0.10 GOPS/DSP using 32-bit quantization, which significantly outperforms previous designs on FPGAs. A real-time application of scene segmentation on Cityscapes Dataset is used to evaluate our CNN accelerator on Zynq ZC706 board, and the system achieves a performance of 107 GOPS and 0.12 GOPS/DSP using 16-bit quantization and supports up to 17 frames per second for 512 × 512 image inputs with a power consumption of only 9.6W.
D
igger
Authors: Liu Xiaoming , Shen Chao , Guan Xiaohong , Zhou Yadong
Published: December 2018

People participate in multiple online social networks, e.g., Facebook, Twitter, and Linkedin, and these social networks with heterogeneous social content and user relationship are named as heterogeneous social networks. Group structure widely exists in heterogeneous social networks, which reveals the evolution of human cooperation. Detecting similar groups in heterogeneous networks has a great significance for many applications, such as recommendation system and spammer detection, using the wealth of group information. Although promising, this novel problem encounters a variety of technical challenges, including incomplete data, high time complexity, and ground truth. To address the research gap and technical challenges, we take advantage of a ratio-cut optimization function to model this novel problem by the linear mixed-effects method and graph spectral theory. Based on this model, we propose an efficient algorithm called D
igger
to detect the similar groups in the large graphs. D
igger
consists of three steps, including measuring user similarity, construct a matching graph, and detecting similar groups. We adopt several strategies to lower the computational cost and detail the basis of labeling the ground truth. We evaluate the effectiveness and efficiency of our algorithm on five different types of online social networks. The extensive experiments show that our method achieves 0.693, 0.783, and 0.735 in precision, recall, and F1-measure, which significantly surpass the state-of-arts by 24.4%, 15.3%, and 20.7%, respectively. The results demonstrate that our proposal can detect similar groups in heterogeneous networks effectively.
Research for practice
Authors: Frazelle Jessie
Published: December 2018

Securely running processes that require the entire syscall interface.
Answering children's questions about computers
Authors: Robertson Judy
Published: December 2018

The
Communications
Web site, http://cacm.acm.org, features more than a dozen bloggers in the BLOG@CACM community. In each issue of
Communications
, we'll publish selected posts or excerpts.

twitter

Follow us on Twitter at http://twitter.com/blogCACM

http://cacm.acm.org/blogs/blog-cacm

Judy Robertson addresses the disconnect between what children are taught about computers and what they actually wish to know.
Hidden messages fool AI
Authors: Edwards Chris
Published: December 2018

Forced errors focus attention on neural network quirks.
CRISPR
Authors: Cusumano Michael A.
Published: December 2018

Considering a potential platform candidate in the evolving realm of gene-editing technologies research.
Fructose reabsorption by rat proximal tubules: role of Na+-linked cotransporters and the effect of dietary fructose
Authors: Gonzalez-Vicente Agustin , Cabral Pablo D. , Hong Nancy J. , Asirwatham Jessica , Saez Fara , Garvin Jeffrey L.
Published: December 2018

Fructose consumption has increased because of widespread use of high-fructose corn syrup by the food industry. Renal proximal tubules are thought to reabsorb fructose. However, fructose reabsorption (Jfructose) by proximal tubules has not yet been directly demonstrated, nor the effects of dietary fructose on Jfructose. This segment expresses Na+- and glucose-linked transporters (SGLTs) 1, 2, 4, and 5 and glucose transporters (GLUTs) 2 and 5. SGLT4 and -5 transport fructose, but SGLT1 and -2 do not. Knocking out SGLT5 increases urinary fructose excretion. We hypothesize that Jfructosein the S2 portion of the proximal tubule is mediated by luminal entry via SGLT4/5 and basolateral exit by GLUT2 and that it is enhanced by a fructose-enriched diet. We measured Jfructoseby proximal straight tubules from rats consuming either tap water (Controls) or 20% fructose (FRU). Basal Jfructosein Controls was 14.1 ± 1.5 pmol·mm−1·min−1. SGLT inhibition with phlorizin reduced Jfructoseto 4.9 ± 1.4 pmol·mm−1·min−1( P < 0.008), whereas removal of Na+diminished Jfructoseby 86 ± 5% ( P < 0.0001). A fructose-enriched diet increased Jfructosefrom 12.8 ± 2.5 to 19.3 ± 0.5 pmol·mm−1·min−1, a 51% increase ( P < 0.03). Using immunofluorescence, we detected luminal SGLT4 and SGLT5 and basolateral GLUT2; GLUT5 was undetectable. The expression of apical transporters SGLT4 and SGLT5 was higher in FRU than in Controls [137 ± 10% ( P < 0.01) and 38 ± 14% ( P < 0.04), respectively]. GLUT2 was also elevated by 88 ± 27% ( P < 0.02) in FRU. We conclude that Jfructoseby proximal tubules occurs primarily via Na+-linked cotransport processes, and a fructose-enriched diet enhances reabsorption. Transport across luminal and basolateral membranes is likely mediated by SGLT4/5 and GLUT2, respectively.
G protein-coupled receptor 37L1 regulates renal sodium transport and blood pressure
Authors: Zheng Xiaoxu , Asico Laureano D. , Ma Xiaobo , Konkalmatt Prasad R.
Published: December 2018

G protein-coupled receptors (GPCRs) in the kidney regulate the reabsorption of essential nutrients, ions, and water from the glomerular filtrate. Abnormalities in renal epithelial ion transport play important roles in the pathogenesis of essential hypertension. The orphan G protein-coupled receptor 37L1 (GPR37L1), also known as endothelin receptor type B-like protein (ETBR-LP2), is expressed in several regions in the brain, but its expression profile and function in peripheral tissues are poorly understood. We found that GPR37L1 mRNA expression is highest in the brain, followed by the stomach, heart, testis, and ovary, with moderate expression in the kidney, pancreas, skeletal muscle, liver, lung, and spleen. Immunofluorescence analyses revealed the expression of GPR37L1 in specific regions within some organs. In the kidney, GPR37L1 is expressed in the apical membrane of renal proximal tubule cells. In human renal proximal tubule cells, the transient expression of GPR37LI increased intracellular sodium, whereas the silencing of GPR37LI decreased intracellular sodium. Inhibition of Na+/H+ exchanger isoform 3 (NHE3) activity abrogated the GPR37L1-mediated increase in intracellular sodium. Renal-selective silencing of Gpr37l1 in mice increased urine output and sodium excretion and decreased systolic and diastolic blood pressures. The renal-selective silencing of GPR37L1 decreased the protein expression of NHE3 but not the expression of Na+-K+-ATPase or sodium-glucose cotransporter 2. Our findings show that in the kidney, GPR37L1 participates in renal proximal tubule luminal sodium transport and regulation of blood pressure by increasing the renal expression and function of NHE3 by decreasing cAMP production. The role of GPR37L1, expressed in specific cell types in organs other than the kidney, remains to be determined.
Dietary oxalate and kidney stone formation
Authors: Mitchell Tanecia , Kumar Parveen , Reddy Thanmaya , Wood Kyle D. , Knight John , Assimos Dean G. , Holmes Ross P.
Published: December 2018

Dietary oxalate is plant-derived and may be a component of vegetables, nuts, fruits, and grains. In normal individuals, approximately half of urinary oxalate is derived from the diet and half from endogenous synthesis. The amount of oxalate excreted in urine plays an important role in calcium oxalate stone formation. Large epidemiological cohort studies have demonstrated that urinary oxalate excretion is a continuous variable when indexed to stone risk. Thus, individuals with oxalate excretions >25 mg/day may benefit from a reduction of urinary oxalate output. The 24-h urine assessment may miss periods of transient surges in urinary oxalate excretion, which may promote stone growth and is a limitation of this analysis. In this review we describe the impact of dietary oxalate and its contribution to stone growth. To limit calcium oxalate stone growth, we advocate that patients maintain appropriate hydration, avoid oxalate-rich foods, and consume an adequate amount of calcium.
Managing free-living hyperglycemia with exercise or interrupted sitting in type 2 diabetes
Authors: Blankenship Jennifer M. , Chipkin Stuart R. , Freedson Patty S. , Staudenmayer John , Lyden Kate , Braun Barry
Published: December 2018

Breaking up sitting with light physical activity (PA) is effective in reducing hyperglycemia in the laboratory. Whether the same effects are observed in the free-living environment remains unknown. We evaluated how daily and postprandial glycemia is impacted by 20, 40, or 60 min of activity performed as either breaks from sitting after each meal (BR) or as one continuous walk after breakfast (WALK). Thirty individuals with type 2 diabetes completed three experimental conditions [BR, WALK, and control (CON)] in a randomized crossover design. Conditions were performed in a free-living environment with strict dietary control over 7 days. Participants increased PA in BR and WALK by 20, 40, or 60 min ( n = 10 in each group) and maintained habitual levels of PA during CON. A continuous glucose monitor (iPro2) and activPAL activity monitor were worn to quantify glycemic control and PA. Using linear mixed models with repeated measures, we 1) compared postprandial glucose (PPG) across conditions and 2) assessed the relationship between activity volume and glucose responses. Whereas WALK tended to shorten the daily duration of hyperglycemia compared with CON ( P = 0.0875), BR was not different from CON. BR and WALK significantly attenuated the breakfast PPG versus CON ( P ≤ 0.05), but lunch and dinner PPG were unaffected by BR and WALK. In conclusion, continuous walking was more effective than breaks from sitting in lowering daily hyperglycemia for the group, but both conditions lowered breakfast PPG. In contrast to tightly controlled laboratory studies, breaks from sitting did not lower hyperglycemia in the free-living environment.

NEW & NOTEWORTHY Our “ecolabical” approach is new and noteworthy. This approach combines the external validity of the free-living environment (ecological) with the control of key confounding variables in the laboratory and allows for highly translatable findings by minimizing confounding variables. We found that both postmeal continuous walking and short breaks from sitting similarly attenuated the postprandial glucose (PPG) response to breakfast. Unlike previous laboratory studies, neither condition (walk after breakfast or postmeal breaks) significantly impacted PPG at lunch or dinner.
Passive changes in muscle length
Authors: Herbert R. D. , Bolsterlee B. , Gandevia S. C.
Published: December 2018

This review, the first in a series of minireviews on the passive mechanical properties of skeletal muscles, seeks to summarize what is known about the muscle deformations that allow relaxed muscles to lengthen and shorten. Most obviously, when a muscle lengthens, muscle fascicles elongate, but this is not the only mechanism by which muscles change their length. In pennate muscles, elongation of muscle fascicles is accompanied by changes in pennation and changes in fascicle curvature, both of which may contribute to changes in muscle length. The contributions of these mechanisms to change in muscle length are usually small under passive conditions. In very pennate muscles with long aponeuroses, fascicle shear could contribute substantially to changes in muscle length. Tendons experience moderate axial strains even under passive loads, and, because tendons are often much longer than muscle fibers, even moderate tendon strains may contribute substantially to changes in muscle length. Data obtained with new imaging techniques suggest that muscle fascicle and aponeurosis strains are highly nonuniform, but this is yet to be confirmed. The development, validation, and interpretation of continuum muscle models informed by rigorous measurements of muscle architecture and material properties should provide further insights into the mechanisms that allow relaxed muscles to lengthen and shorten.
Type 2 diabetes mellitus in the Goto-Kakizaki rat impairs microvascular function and contributes to premature skeletal muscle fatigue
Authors: Frisbee Jefferson C. , Lewis Matthew T. , Kasper Jonathan D. , Chantler Paul D. , Wiseman Robert W.
Published: December 2018

Despite extensive investigation into the impact of metabolic disease on vascular function and, by extension, tissue perfusion and organ function, interpreting results for specific risk factors can be complicated by the additional risks present in most models. To specifically determine the impact of type 2 diabetes without obesity on skeletal muscle microvascular structure/function and on active hyperemia with elevated metabolic demand, we used 17-wk-old Goto-Kakizaki (GK) rats to study microvascular function at multiple levels of resolution. Gracilis muscle arterioles demonstrated blunted dilation to acetylcholine (both ex vivo proximal and in situ distal arterioles) and elevated shear (distal arterioles only). All other alterations to reactivity appeared to reflect compromised endothelial function associated with increased thromboxane (Tx)A2 production and oxidant stress/inflammation rather than alterations to vascular smooth muscle function. Structural changes to the microcirculation of GK rats were confined to reduced microvessel density of ~12%, with no evidence for altered vascular wall mechanics. Active hyperemia with either field stimulation of in situ cremaster muscle or electrical stimulation via the sciatic nerve for in situ gastrocnemius muscle was blunted in GK rats, primarily because of blunted functional dilation of skeletal muscle arterioles. The blunted active hyperemia was associated with impaired oxygen uptake (V̇o2) across the muscle and accelerated muscle fatigue. Acute interventions to reduce oxidant stress (TEMPOL) and TxA2 action (SQ-29548) or production (dazmegrel) improved muscle perfusion, V̇o2, and muscle performance. These results suggest that type 2 diabetes mellitus in GK rats impairs skeletal muscle arteriolar function apparently early in the progression of the disease and potentially via an increased reactive oxygen species/inflammation-induced TxA2 production/action on network function as a major contributing mechanism.

NEW & NOTEWORTHY The impact of type 2 diabetes mellitus on vascular structure/function remains an area lacking clarity. Using diabetic Goto-Kakizaki rats before the development of other risk factors, we determined alterations to vascular structure/function and skeletal muscle active hyperemia. Type 2 diabetes mellitus reduced arteriolar endothelium-dependent dilation associated with increased thromboxane A2 generation. Although modest microvascular rarefaction was evident, there were no other alterations to vascular structure/function. Skeletal muscle active hyperemia was blunted, although it improved after antioxidant or anti-thromboxane A2 treatment.
Peripheral blood mononuclear cells do not reflect skeletal muscle mitochondrial function or adaptation to high-intensity interval training in healthy young men
Authors: Hedges C. P. , Woodhead J. S. T. , Wang H. W. , Mitchell C. J. , Cameron-Smith D. , Hickey A. J. R. , Merry T. L.
Published: December 2018

Measurement of skeletal muscle mitochondrial respiration requires invasive biopsy to obtain a muscle sample. Peripheral blood mononuclear cell (PBMC) mitochondrial protein content appears to reflect training status in young men; however, no studies have investigated whether there are training-induced changes in PBMC mitochondrial respiration. Therefore, we determined whether PBMC mitochondrial respiration could be used as a marker of skeletal muscle mitochondrial respiration in young healthy men and whether PBMC mitochondrial respiration responds to short-term training. Skeletal muscle and PBMC samples from 10 healthy young (18–35 yr) male participants were taken before and after a 2-wk high-intensity interval training protocol. High-resolution respirometry was used to determine mitochondrial respiration from muscle and PBMCs, and Western blotting and quantitative PCR were used to assess mitochondrial biogenesis in PBMCs. PBMC mitochondrial respiration was not correlated with muscle mitochondrial respiration at baseline ( R2 = 0.012–0.364, P > 0.05). While muscle mitochondrial respiration increased in response to training (32.1–61.5%, P < 0.05), PBMC respiration was not affected by training. Consequently, PBMCs did not predict training effect on muscle mitochondrial respiration ( R2 = 0.024–0.283, P > 0.05). Similarly, gene and protein markers of mitochondrial biogenesis did not increase in PBMCs following training. This suggests PBMC mitochondrial function does not reflect that of skeletal muscle and does not increase following short-term high-intensity training. PBMCs are therefore not a suitable biomarker for muscle mitochondrial function in young healthy men. It may be useful to study PBMC mitochondrial function as a biomarker of muscle mitochondrial function in pathological populations with different respiration capacities.

NEW & NOTEWORTHY Research in primates has suggested that peripheral blood mononuclear cells (PBMCs) may provide a less-invasive alternative to a muscle biopsy for measuring muscle mitochondrial function. Furthermore, trained individuals appear to have greater mitochondrial content in PBMCs. Here we show that in healthy young men, PBMCs do not reflect skeletal muscle mitochondrial function and do not adapt in response to a training intervention that increases muscle mitochondrial function, suggesting PBMCs are a poor marker of muscle mitochondrial function in humans.
Effects of prostate cancer and exercise training on left ventricular function and cardiac and skeletal muscle mass
Authors: Baumfalk Dryden R. , Opoku-Acheampong Alexander B. , Caldwell Jacob T. , Ade Carl J. , Copp Steven W. , Musch Timothy I. , Behnke Bradley J.
Published: December 2018

Prostate cancer was found to reduce cardiac and left ventricle (LV) masses in association with diminished exercise capacity in rats. We tested the hypothesis that exercise training will mitigate prostate cancer-induced cardiac and skeletal muscle atrophy and improve LV function versus sedentary tumor-bearing counterparts. Copenhagen rats ( n = 39; ~5 mo old) were randomized into four groups: exercise-trained tumor-bearing (EXTB) or control (EXCON) and sedentary tumor-bearing (SEDTB) or control (SEDCON). Dunning R-3327 prostate cancer cells were injected orthotopically in 19 of the 39 animals. Treadmill exercise training was performed for 60 min/day for ~30 days. Animals underwent echocardiography to examine ventricle dimensions “Pre-” cancer injection or exercise (PRE) and 15 (Post 1) and 32–35 (Post 2) days after cancer cell injection with tissues collected after Post 2. LV TNF-α and IL-6 concentrations were measured post mortem. Cardiac and LV mass of SEDTB animals were lower than all groups ( P < 0.05). Tumor mass was negatively correlated with LV mass in EXTB (−0.75, P < 0.02) and SEDTB animals (−0.72, P < 0.02). EXCON group had higher stroke volume Post 2 assessment compared with both sedentary groups ( P < 0.05) but not EXTB animals. No difference in LV [IL-6] or [TNF-α] was found between the cancer groups. The current investigation demonstrates prostate cancer, independent of anticancer treatment, significantly reduces cardiac mass and LV mass as well as locomotor muscle masses. However, moderate-intensity exercise training can mitigate cardiac and skeletal muscle atrophy with prostate cancer and preserve the cardiac phenotype (i.e., mass and function) to that of the healthy sedentary group.

NEW & NOTEWORTHY This study demonstrates the atrophic effects of prostate cancer on cardiac and skeletal muscle mass independent of anticancer treatment(s) that can be mitigated with moderate-intensity exercise. These findings have important implications for potentially improving the quality of life as well as therapeutic outcomes for patients with prostate cancer.