bluuebunny/crossref_metadata_2025 huggingface dataset:
Random forests and stochastic gradient boosting for predicting tree canopy cover: comparing tuning processes and model performance
Authors: Freeman Elizabeth A. , Moisen Gretchen G. , Coulston John W. , Wilson Barry T.
Published: August 2015

As part of the development of the 2011 National Land Cover Database (NLCD) tree canopy cover layer, a pilot project was launched to test the use of high-resolution photography coupled with extensive ancillary data to map the distribution of tree canopy cover over four study regions in the conterminous US. Two stochastic modeling techniques, random forests (RF) and stochastic gradient boosting (SGB), are compared. The objectives of this study were first to explore the sensitivity of RF and SGB to choices in tuning parameters and, second, to compare the performance of the two final models by assessing the importance of, and interaction between, predictor variables, the global accuracy metrics derived from an independent test set, as well as the visual quality of the resultant maps of tree canopy cover. The predictive accuracy of RF and SGB was remarkably similar on all four of our pilot regions. In all four study regions, the independent test set mean squared error (MSE) was identical to three decimal places, with the largest difference in Kansas where RF gave an MSE of 0.0113 and SGB gave an MSE of 0.0117. With correlated predictor variables, SGB had a tendency to concentrate variable importance in fewer variables, whereas RF tended to spread importance among more variables. RF is simpler to implement than SGB, as RF has fewer parameters needing tuning and also was less sensitive to these parameters. As stochastic techniques, both RF and SGB introduce a new component of uncertainty: repeated model runs will potentially result in different final predictions. We demonstrate how RF allows the production of a spatially explicit map of this stochastic uncertainty of the final model.
Detection of Terahertz Radiation by Dense Arrays of InGaAs Transistors
Authors: Yermolayev D. M. , Polushkin E. A. , Shapoval S. Yu. , Popov V. V. , Marem’yanin K. V. , Gavrilenko V. I. , Maleev N. A. , Ustinov V. M. , Zemlyakov V. E. , Yegorkin V. I. , Bespalov V. A. , Muravjov A. V. , Rumyantsev S. L. , Shur M. S.
Published: August 2015

Detection of terahertz radiation by GaAs transistor structures has been studied experimentally. The two types of samples under study included dense arrays of HEMTs and large-apertures detectors. Arrays consisted of parallel and series chains with asymmetric gate transistors for enhanced photoresponse on terahertz radiation. We investigated two types of wide-aperture detectors: grating gate detector, and single gate detector with bow-tie antenna. Wide-aperture detectors were symmetrical. Studies of transistor chains have shown that two essential features for this type of detector are the presence of asymmetry in the gate, and the type of connection between individual transistors themselves. Wide-aperture detectors have also been tested by narrow beams of terahertz radiation, which allows analyzing the role influence of individual parts of the detector for total sensitivity to terahertz excitation. The sensitivity and noise equivalent power of the detectors were evaluated.
A deterministic pseudo-fractal networks with time-delay
Authors: Xing Changming , Yang Lin , Ma Jun
Published: August 2015

In this paper, inspired by the pseudo-fractal networks (PFN) and the delayed pseudo-fractal networks (DPFN), we present a novel delayed pseudo-fractal networks model, denoted by NDPFN. Different from the generation algorithm of those two networks, every edge of the novel model has a time-delay to generate new nodes after producing one node. We derive exactly the main structural properties of the novel networks: degree distribution, clustering coefficient, diameter and average path length. Analytical results show that the novel networks have small-world effect and scale-free topology. Comparing topological parameters of these three networks, we find that the degree exponent of the novel networks is the largest while the clustering coefficient and the average path length are the smallest. It means that this kind of delay could weaken the heterogeneity and the small-world features of the network. Particularly, the delay effect in the NDPFN is contrary to that in the DPFN, which illustrates the variety of delay method could produce different effects on the network structure. These present findings may be helpful for a deeper understanding of the time-delay influence on the network topology.
New generalized corresponding states correlation for surface tension of normal saturated liquids
Authors: Yi Huili , Tian Jianxiang
Published: August 2015

A new simple correlation based on the principle of corresponding state is proposed to estimate the temperature-dependent surface tension of normal saturated liquids. The new correlation contains three coefficients obtained by fitting 17,051 surface tension data of 38 saturated normal liquids. These 38 liquids contain refrigerants, hydrocarbons and some other inorganic liquids. The new correlation requires only the triple point temperature, triple point surface tension and critical point temperature as input and is able to well represent the experimental surface tension data for each of the 38 saturated normal liquids from the triple temperature up to the point near the critical point. The new correlation gives absolute average deviations (AAD) values below 3% for all of these 38 liquids with the only exception being octane with AAD=4.30%. Thus, the new correlation gives better overall results in comparison with other correlations for these 38 normal saturated liquids.
Geometric Limits of Julia Sets of Maps zn + exp(2πiθ) as n → ∞
Authors: Kaschner Scott R. , Romero Reaper , Simmons David
Published: August 2015

We show that the geometric limit as n → ∞ of the Julia sets J(Pn,c) for the maps Pn,c(z) = zn + c does not exist for almost every c on the unit circle. Furthermore, we show that there is always a subsequence along which the limit does exist and equals the unit circle.
Rank One Chaos in Periodically-Kicked Time-Delayed Chen System
Authors: Dai Yunxian , Lin Yiping , Yang Wenjie , Zhao Huitao
Published: August 2015

In this paper, we study the existence of rank one strange attractor in time-delayed system. First, we try to develop rank one theory for delayed differential equations. Then, we consider Chen system with time-delay, the conditions under which a supercritical Hopf bifurcation occurs are given by using the normal form method and center manifold theorem. Then, we add an external periodic force as an input and observe rank one strange attractors. Finally, several numerical simulations supporting the theoretical analysis are also given.
Pullback and Uniform Exponential Attractors for Nonautonomous Boussinesq Lattice System
Authors: Zhao Min , Zhou Shengfan
Published: August 2015

We first prove the existence of a pullback attractor and a pullback exponential attractor for a nonautonomous lattice dynamical system of nonlinear Boussinesq equations affected by time-dependent coupled coefficients and forces. Then, we prove the existence of a uniform attractor and a uniform exponential attractor for the system driven by quasi-periodic external forces.
On the Chaotic Vibrations of Electrostatically Actuated Arch Micro/Nano Resonators: A Parametric Study
Authors: Tajaddodianfar Farid , Hairi Yazdi Mohammad Reza , Pishkenari Hossein Nejat
Published: August 2015

Motivated by specific applications, electrostatically actuated bistable arch shaped micro-nano resonators have attracted growing attention in the research community in recent years. Nevertheless, some issues relating to their nonlinear dynamics, including the possibility of chaos, are still not well known. In this paper, we investigate the chaotic vibrations of a bistable resonator comprised of a double clamped initially curved microbeam under combined harmonic AC and static DC distributed electrostatic actuation. A reduced order equation obtained by the application of the Galerkin method to the nonlinear partial differential equation of motion, given in the framework of Euler–Bernoulli beam theory, is used for the investigation in this paper. We numerically integrate the obtained equation to study the chaotic vibrations of the proposed system. Moreover, we investigate the effects of various parameters including the arch curvature, the actuation parameters and the quality factor of the resonator, which are effective in the formation of both static and dynamic behaviors of the system. Using appropriate numerical tools, including Poincaré maps, bifurcation diagrams, Fourier spectrum and Lyapunov exponents we scrutinize the effects of various parameters on the formation of chaotic regions in the parametric space of the resonator. Results of this work provide better insight into the problem of nonlinear dynamics of the investigated family of bistable micro/nano resonators, and facilitate the design of arch resonators for applications such as filters.
AVHotRR: near-real time routine for volcano monitoring using IR satellite data
Authors: Lombardo Valerio
Published: August 2015

The AVHotRR routine has been in operation since 2006 to process satellite data for monitoring active volcanoes in the Mediterranean area. Although originally developed to work with advanced very high-resolution radiometer (AVHRR) data, AVHotRR has been developed over the years to adapt to other sensors. In this work we present an improved version of the algorithm for hot-spot detection and effusion rate estimate. The underlying principles upon which the algorithm is based are discussed, focusing on the enhancements. The currently implemented version makes it possible to integrate results from different datasets in order to better constrain the detection of volcanic hot spots. In particular, the high temporal resolution of the SEVIRI instrument aboard MSG is key to reducing false positives in AVHRR and moderate resolution imaging spectroradiometer MODIS images. We propose here a new detection method based on the wavelet transform of SEVIRI data. Results from the application of AVHotRR to a dataset of AVHRR and SEVIRI images from Mt Etna, Italy, are presented and discussed with reference to the advantages and limitations of the algorithm.
A Write-Aware STTRAM-Based Register File Architecture for GPGPU
Authors: Wang Jue , Xie Yuan
Published: August 2015

The massively parallel processing capacity of GPGPUs requires a large register file (RF), and its size keeps increasing to support more concurrent threads from generation to generation. Using traditional SRAM-based RFs, there are concerns in both area cost and energy consumption, and soon they will become unrealistic. In this work, we analyze the feasibility of using STTRAM-based RF designs, which have benefits in terms of smaller silicon area and zero standby leakage power. However, STTRAM long write latency and high write energy bring new challenges. Therefore, we propose a write-aware STTRAM-based RF architecture (WarRF), which contains two techniques:
Split Bank Write
modifies the arbitrator design to increase the parallelism of read and write accesses in the same bank;
Write Pool
reduces the number of repeated write accesses to RFs. Our experiment shows that the performance of STTRAM-based RF is improved by 13% and up to 23% after adopting WarRF. In addition, the energy consumption is reduced by 38% on average compared to SRAM-based RFs.
mNoC
Authors: Pang Jun , Dwyer Christopher , Lebeck Alvin R.
Published: August 2015

Moore's law and the continuity of device scaling have led to an increasing number of cores/nodes on a chip, creating a need for new mechanisms to achieve high-performance and power-efficient Network-on-Chip (NoC). Nanophotonics based NoCs provide for higher bandwidth and more power efficient designs than electronic networks. Present approaches often use an external laser source, ring resonators, and waveguides. However, they still suffer from important limitations: large static power consumption, and limited network scalability.

In this article, we explore the use of emerging molecular scale devices to construct nanophotonic networks: Molecular-scale Network-on-Chip (mNoC). We leverage on-chip emitters such as quantum dot LEDs, which provide electrical to optical signal modulation, and chromophores, which provide optical signal filtering for receivers. These devices replace the ring resonators and the external laser source used in contemporary nanophotonic NoCs. They reduce energy consumption or enable scaling to larger crossbars for a reduced energy budget. We present a Single Writer Multiple Reader (SWMR) bus based crossbar mNoC. Our evaluation shows that an mNoC can achieve more than 88% reduction in energy for a 64×64 crossbar compared to similar ring resonator based designs. Additionally, an mNoC can scale to a 256×256 crossbar with an average 10% performance improvement and 54% energy reduction.
A Sub-μ A Stand-By Current Synchronous Electric Charge Extractor for Piezoelectric Energy Harvesting
Authors: Romani Aldo , Filippi Matteo , Dini Michele , Tartagni Marco
Published: August 2015

In the field of energy harvesting there is a growing interest in power management circuits with intrinsic sub-μ A current consumptions, in order to operate efficiently with very low levels of available power. In this context, integrated circuits proved to be a viable solution with high associated nonrecurring costs and design risks. As an alternative, this article presents a fully autonomous and battery-less circuit solution for piezoelectric energy harvesting based on discrete components in a low-cost PCB technology, which achieves a comparable performance in a 32 × 43 mm
2
footprint. The power management circuit implements synchronous electric charge extraction (SECE) with a passive bootstrap circuit from fully discharged states. Circuit characterization showed that the circuit consumes less than 1μ A with a 3V output and may achieve energy conversion efficiencies of up to 85%. In addition, the circuit is specifically designed for operating with input and output voltages up to 20V, which grants a significant flexibility in the choice of transducers and energy storage capacitors.
MN-MATE
Authors: Park Kyu Ho , Hwang Woomin , Seok Hyunchul , Kim Chulmin , Shin Dong-jae , Kim Dong Jin , Maeng Min Kyu , Kim Seong Min
Published: August 2015

Recent advent of manycore system increases needs for larger but faster memory hierarchy. Emerging next generation memories such as on-chip DRAM and nonvolatile memory (NVRAM) are promising candidates for replacement of DRAM-only main memory. Combined with the manycore trends, it gives an opportunity to rethink conventional resource management system with a memory hierarchy for a single cloud node. In an attempt to mitigate the energy and memory problems, we propose MN-MATE, an elastic resource management architecture for a single cloud node with manycores, on-chip DRAM, and large size of off-chip DRAM and NVRAM. In MN-MATE, the hypervisor places consolidated VMs and balances memory among them. Based on the monitored information about the allocated memory, a guest OS co-schedules tasks accessing different types of memory with complementary access intensity. Polymorphic management of DRAM hierarchy accelerates average memory access speed inside each guest OS. A guest OS reduces energy consumption with small performance loss based on the NVRAM-aware data placement policy and the hybrid page cache. A new lightweight kernel is developed to reduce the overhead from the guest OS for scientific applications. Experiment results show that our techniques in MN-MATE platform improve system performance and reduce energy consumption.
The Efficiency of Fair Division with Connected Pieces
Authors: Aumann Yonatan , Dombb Yair
Published: August 2015

The cake-cutting setting, in which a single heterogeneous good must be divided between multiple parties with different tastes, is a classic model for studying questions regarding fairness in resource allocation. In this work, we turn our attention to (economic) efficiency considerations in cake cutting, examining the possible trade-offs between meeting the fairness criteria, on the one hand, and maximizing social welfare, on the other. We focus on divisions that give each agent a single (contiguous) piece of the cake and provide tight bounds (or, in some cases, nearly tight) on the possible degradation in utilitarian and egalitarian welfare resulting from meeting the fairness requirements.
Affine Maximizers in Domains with Selfish Valuations
Authors: Nath Swaprava , Sen Arunava
Published: August 2015

We consider the domain of
selfish
and
continuous
preferences over a “rich” allocation space and show that onto, strategyproof and
allocation non-bossy
social choice functions are affine maximizers. Roberts [1979] proves this result for a finite set of alternatives and an unrestricted valuation space. In this article, we show that in a subdomain of the unrestricted valuations with the additional assumption of
allocation non-bossiness
, using the richness of the allocations, the strategyproof social choice functions can be shown to be affine maximizers. We provide an example to show that allocation non-bossiness is indeed critical for this result. This work shows that an affine maximizer result needs a certain amount of richness split across valuations and allocations.
Truthfulness Flooded Domains and the Power of Verification for Mechanism Design
Authors: Fotakis Dimitris , Zampetakis Emmanouil
Published: August 2015

In this work, we investigate the reasons that make symmetric partial verification essentially useless in virtually all domains. Departing from previous work, we consider any possible (finite or infinite) domain and general symmetric verification. We identify a natural property, namely, that the correspondence graph of a symmetric verification
M
is strongly connected by finite paths along which the preferences are consistent with the preferences at the endpoints, and prove that this property is sufficient for the equivalence of truthfulness and
M
-truthfulness. In fact, defining appropriate versions of this property, we obtain this result for deterministic and randomized mechanisms with and without money. Moreover, we show that a slightly relaxed version of this property is also necessary for the equivalence of truthfulness and
M
-truthfulness. Our conditions provide a generic and convenient way of checking whether truthful implementation can take advantage of any symmetric verification scheme in any (finite or infinite) domain. Since the simplest symmetric verification is the local verification, specific cases of our result are closely related, in the case without money, to the research about the equivalence of local truthfulness and global truthfulness. To complete the picture, we consider asymmetric verification and prove that a social choice function is
M
-truthfully implementable by some asymmetric verification
M
if and only if
f
does not admit a cycle of profitable deviations.
Revenue Maximization with Nonexcludable Goods
Authors: Bateni Mohammadhossein , Haghpanah Nima , Sivan Balasubramanian , Zadimoghaddam Morteza
Published: August 2015

We study the design of revenue-maximizing mechanisms for selling nonexcludable public goods. In particular, we study revenue-maximizing mechanisms in Bayesian settings for facility location problems on graphs where no agent can be excluded from using a facility that has been constructed. We show that the pointwise optimization problem involved in implementing the revenue optimal mechanism, namely, optimizing over arbitrary profiles of virtual values, is hard to approximate within a factor of Ω(
n
2-ε
) (assuming
P
≠
NP
) even in star graphs. Furthermore, we show that optimizing the expected revenue is APX-hard. However, in a relevant special case, rooted version with identical distributions, we construct polynomial time truthful mechanisms that approximate the optimal expected revenue within a constant factor. We also study the effect of partially mitigating nonexcludability by collecting tolls for using the facilities. We show that such “posted-price” mechanisms obtain significantly higher revenue and often approach the optimal revenue obtainable with full excludability.
Near-Optimal and Robust Mechanism Design for Covering Problems with Correlated Players
Authors: Minooei Hadi , Swamy Chaitanya
Published: August 2015

We consider the problem of designing incentive-compatible, ex-post individually rational (IR) mechanisms for covering problems in the Bayesian setting, where players' types are drawn from an underlying distribution and may be correlated, and the goal is to minimize the expected total payment made by the mechanism. We formulate a notion of incentive compatibility (IC) that we call
support-based IC
that is substantially more robust than Bayesian IC, and develop black-box reductions from support-based-IC mechanism design to algorithm design. For single-dimensional settings, this black-box reduction applies even when we only have an LP-relative
approximation algorithm
for the algorithmic problem. Thus, we obtain near-optimal mechanisms for various covering settings, including single-dimensional covering problems, multi-item procurement auctions, and multidimensional facility location.
SCKVdd
Authors: Cheng Ching-Hwa
Published: August 2015

It has been proposed that small amounts of energy dissipate when transfer through a rising Vdd. In typical power gate circuits, the PMOS transistors (P
SW
) reduce the leakage of power by shutting off outer Vdd to the idle blocks. We expand this technique by utilizing active P
SW
, which are turned on and off by a clock signal. The proposed SCKVdd technique combines the power source gated mechanism and clock signal to generate stable progressive rising voltage to suppress peak and average currents effectively. The SCKVdd technique is a scalable, clock-controlled, self-stabilized voltage technique. This technique is easily implemented in generic digital circuits to reduce power dissipation. A normal CMOS circuit shows a dynamic power consumption increase proportional to the clock frequency. SCKVdd results in a lower-than-usual frequency dependency, and is suitable for high speed clock circuits. SCKVdd can be integrated with frequency, voltage scaling and an activated P
SW
number to implement an efficient power-performance trade-off mechanism. In experiments that investigated constant Vdd for MPEG VLD chips, power dissipation savings were in the range of 42% to 54% with only a small delay penalty.
Reproductive Factors but Not Hormonal Factors Associated with Thyroid Cancer Risk: A Systematic Review and Meta-Analysis
Authors: Cao Yijuan , Wang Zengyan , Gu Juan , Hu Fangfang , Qi Yujuan , Yin Qianqian , Sun Qingqing , Li Guotao , Quan Bin
Published: August 2015

Many studies have investigated the association between hormonal and reproductive factors and thyroid cancer risk but provided contradictory and inconclusive findings. This review was aimed at precisely estimating this association by pooling all available epidemiological studies. 25 independent studies were retrieved after a comprehensive literature search in databases of PubMed and Embase. Overall, common hormonal factors including oral contraceptive and hormone replacement therapy did not alter the risk of thyroid cancer. Older age at menopause was associated with weakly increased risk of thyroid cancer in overall analysis (RR = 1.24, 95% CI 1.00–1.53,P=0.049); however, longer duration of breast feeding was related to moderately reduced risk of thyroid cancer, suggested by pooled analysis in all cohort studies (RR = 0.7, 95% CI 0.51–0.95,P=0.021). The pooled RR in hospital-based case-control studies implicated that parous women were more susceptible to thyroid cancer than nulliparous women (RR = 2.30, 95% CI 1.31–4.04,P=0.004). The present meta-analysis suggests that older age at menopause and parity are risk factors for thyroid cancer, while longer duration of breast feeding plays a protective role against this cancer. Nevertheless, more relevant epidemiological studies are warranted to investigate roles of hormonal and reproductive factors in thyroid carcinogenesis.
Effect of Dietaryω-3 Polyunsaturated Fatty Acid DHA on Glycolytic Enzymes and Warburg Phenotypes in Cancer
Authors: Manzi Laura , Costantini Lara , Molinari Romina , Merendino Nicolò
Published: August 2015

The omega-3 polyunsaturated fatty acids (ω-3 PUFAs) are a class of lipids that has been shown to have beneficial effects on some chronic degenerative diseases such as cardiovascular diseases, rheumatoid arthritis, inflammatory disorders, diabetes, and cancer. Amongω-3 polyunsaturated fatty acids (PUFAs), docosahexaenoic acid (DHA) has received particular attention for its antiproliferative, proapoptotic, antiangiogenetic, anti-invasion, and antimetastatic properties, even though the involved molecular mechanisms are not well understood. Recently, somein vitrostudies showed that DHA promotes the inhibition of glycolytic enzymes and the Warburg phenotype. For example, it was shown that in breast cancer cell lines the modulation of bioenergetic functions is due to the capacity of DHA to activate the AMPK signalling and negatively regulate the HIF-1αfunctions. Taking into account these considerations, this review is focused on current knowledge concerning the role of DHA in interfering with cancer cell metabolism; this could be considered a further mechanism by which DHA inhibits cancer cell survival and progression.
Improvement of Biodegradable Biocide’s Activity of Peroxyacetic Acid Basis Using Surfactants: Characterization and Stability
Authors: Asensio Esther , Sanagustín Fernando , Nerín Cristina , Rosero-Moreano Milton
Published: August 2015

This paper deals with the study of the kinetics decomposition reaction of the peroxyacetic acid under influence of surfactant additives. The peroxyacetic acid shows a decomposition rate of 1.70×10−3 h−1and its activation energy is 66 kJ mol−1. The influence of temperature on the reaction of spontaneous decomposition of peroxyacetic acid was studied at two seasonal periods. Peroxyacetic acid standard and four prototypes of biocide samples with known concentration of peroxyacetic acid and hydrogen peroxide were studied. Finally, a factorial analysis ANOVA was carried out to establish significant differences (p<0.003) between the four biocide samples over time with respect to peroxyacetic acid and hydrogen peroxide concentration. From the study carried out, it can be concluded that the biocide with surfactant substances in its composition offers the best stability and its difference versus the other biocides may guarantee a better behaviour.
The Use of Virtual Reality in Psychology: A Case Study in Visual Perception
Authors: Wilson Christopher J. , Soranzo Alessandro
Published: August 2015

Recent proliferation of available virtual reality (VR) tools has seen increased use in psychological research. This is due to a number of advantages afforded over traditional experimental apparatus such as tighter control of the environment and the possibility of creating more ecologically valid stimulus presentation and response protocols. At the same time, higher levels of immersion and visual fidelity afforded by VR do not necessarily evoke presence or elicit a “realistic” psychological response. The current paper reviews some current uses for VR environments in psychological research and discusses some ongoing questions for researchers. Finally, we focus on the area of visual perception, where both the advantages and challenges of VR are particularly salient.
Acute Lymphoblastic Leukemia Cells Inhibit the Differentiation of Bone Mesenchymal Stem Cells into Osteoblasts In Vitro by Activating Notch Signaling
Authors: Yang Gui-Cun , Xu You-Hua , Chen Hong-Xia , Wang Xiao-Jing
Published: August 2015

The disruption of normal hematopoiesis has been observed in leukemia, but the mechanism is unclear. Osteoblasts originate from bone mesenchymal stem cells (BMSCs) and can maintain normal hematopoiesis. To investigate how leukemic cells inhibit the osteogenic differentiation of BMSCs and the role of Notch signaling in this process, we cocultured BMSCs with acute lymphoblastic leukemia (ALL) cells in osteogenic induction medium. The expression levels of Notch1, Hes1, and the osteogenic markers Runx2, Osteopontin (OPN), and Osteocalcin (OCN) were assessed by real-time RT-PCR and western blotting on day 3. Alkaline phosphatase (ALP) activity was analyzed using an ALP kit, and mineralization deposits were detected by Alizarin red S staining on day 14. And then we treated BMSCs with Jagged1 and anti-Jagged1 neutralizing Ab. The expression of Notch1, Hes1, and the abovementioned osteogenic differentiation markers was measured. Inhibition of the expression of Runx2, OPN, and OCN and reduction of ALP activity and mineralization deposits were observed in BMSCs cocultured with ALL cells, while Notch signal inhibiting rescued these effects. All these results indicated that ALL cells could inhibit the osteogenic differentiation of BMSCs by activating Notch signaling, resulting in a decreased number of osteoblastic cells, which may impair normal hematopoiesis.
Prenatal Exposure to Sodium Arsenite Alters Placental Glucose 1, 3, and 4 Transporters in Balb/c Mice
Authors: Gutiérrez-Torres Daniela Sarahí , González-Horta Carmen , Del Razo Luz María , Infante-Ramírez Rocío , Ramos-Martínez Ernesto , Levario-Carrillo Margarita , Sánchez-Ramírez Blanca
Published: August 2015

Inorganic arsenic (iAs) exposure induces a decrease in glucose type 4 transporter (GLUT4) expression on the adipocyte membrane, which may be related to premature births and low birth weight infants in women exposed to iAs at reproductive age. The aim of this study was to analyze the effect of sodium arsenite (NaAsO2) exposure on GLUT1, GLUT3, and GLUT4 protein expression and on placental morphology. Female Balb/c mice (n=15) were exposed to 0, 12, and 20 ppm of NaAsO2in drinking water from 8th to 18th day of gestation. Morphological changes and GLUT1, GLUT3, and GLUT4 expression were evaluated in placentas by immunohistochemical and image analysis and correlated with iAs and arsenical species concentration, which were quantified by atomic absorption spectroscopy. NaAsO2exposure induced a significant decrease in fetal and placental weight (P<0.01) and increases in infarctions and vascular congestion. Whereas GLUT1 expression was unchanged in placentas from exposed group, GLUT3 expression was found increased. In contrast, GLUT4 expression was significantly lower (P<0.05) in placentas from females exposed to 12 ppm. The decrease in placental GLUT4 expression might affect the provision of adequate fetal nutrition and explain the low fetal weight observed in the exposed groups.
Improving the Mapping of Smith-Waterman Sequence Database Searches onto CUDA-Enabled GPUs
Authors: Huang Liang-Tsung , Wu Chao-Chin , Lai Lien-Fu , Li Yun-Ju
Published: August 2015

Sequence alignment lies at heart of the bioinformatics. The Smith-Waterman algorithm is one of the key sequence search algorithms and has gained popularity due to improved implementations and rapidly increasing compute power. Recently, the Smith-Waterman algorithm has been successfully mapped onto the emerging general-purpose graphics processing units (GPUs). In this paper, we focused on how to improve the mapping, especially for short query sequences, by better usage of shared memory. We performed and evaluated the proposed method on two different platforms (Tesla C1060 and Tesla K20) and compared it with two classic methods in CUDASW++. Further, the performance on different numbers of threads and blocks has been analyzed. The results showed that the proposed method significantly improves Smith-Waterman algorithm on CUDA-enabled GPUs in proper allocation of block and thread numbers.
Genotoxic Effect in Autoimmune Diseases Evaluated by the Micronucleus Test Assay: Our Experience and Literature Review
Authors: Torres-Bugarín Olivia , Macriz Romero Nicole , Ramos Ibarra María Luisa , Flores-García Aurelio , Valdez Aburto Penélope , Zavala-Cerna María Guadalupe
Published: August 2015

Autoimmune diseases (AD) are classified into organ-specific, systemic, and mixed; all forms of AD share a high risk for cancer development. In AD a destructive immune response induced by autoreactive lymphocytes is started and continues with the production of autoantibodies against different targets; furthermore apoptosis failure and loss of balance in oxidative stress as a consequence of local or systemic inflammation are common features seen in AD as well. Micronucleus (MN) assay can be performed in order to evaluate loss of genetic material in a clear, accurate, fast, simple, and minimally invasive test. The MN formation in the cytoplasm of cells that have undergone proliferation is a consequence of DNA fragmentation during mitosis and the appearance of small additional nuclei during interphase. The MN test, widely accepted forin vitroandin vivogenotoxicity research, provides a sensitive marker of genomic damage associated to diverse conditions. In here, we present a review of our work and other published papers concerning genotoxic effect in AD, identified by means of the MN assay, with the aim of proposing this tool as a possible early biomarker for genotoxic damage, which is a consequence of disease progression. Additionally this biomarker could be used for follow-up, to asses genome damage associated to therapies.
Association between Genetic Polymorphisms of DNA Repair Genes and Chromosomal Damage for 1,3-Butadiene-Exposed Workers in a Matched Study in China
Authors: Xiang Menglong , Sun Lei , Dong Xiaomei , Yang Huan , Liu Wen-bin , Zhou Niya , Han Xue , Zhou Ziyuan , Cui Zhihong , Liu Jing-yi , Cao Jia , Ao Lin
Published: August 2015

The aim of the study was to examine the association between polymorphisms of DNA repair genes and chromosomal damage of 1,3-butadiene- (BD-) exposed workers. The study was conducted in 45 pairs of occupationally exposed workers in a BD product workshop and matched control workers in an administrative office and a circulatory water workshop in China. Newly developed biomarkers (micronuclei, MNi; nucleoplasmic bridges, NPBs; nuclear buds, NBUDs) in the cytokinesis-blocked micronucleus (CBMN) cytome assay were adopted to detect chromosomal damage. PCR and PCR-restriction fragment length polymorphism (RFLP) are adopted to analyze polymorphisms of DNA repair genes, such as X-ray repair cross-complementing Group 1 (XRCC1), O6-methylguanine-DNA methyltransferase (MGMT), poly (adenosine diphosphate-ribose) polymerases (ADPRT), and apurinic/apyrimidinic endonucleases (APE1). The BD-exposed workers exhibited increased frequencies of MNi and NPBs when compared to subjects in the control group. The results also show that the BD-exposed workers carryingXRCC1diplotypesTCGA-CCGG(4.25±2.06‰) (FR=2.10, 95% CI: 1.03–4.28) andTCGG-TCGA(5.80±3.56‰) (FR=2.75, 95% CI: 0.76–2.65) had statistically higher NBUD frequencies than those who carried diplotypeTCGG-TCGG(1.89±1.27‰). Our study suggests that polymorphisms ofXRCC1gene may influence chromosomal damage in BD-exposed workers.
Docosahexaenoic Acid Induces Cell Death in Human Non-Small Cell Lung Cancer Cells by Repressing mTOR via AMPK Activation and PI3K/Akt Inhibition
Authors: Kim Nayeong , Jeong Soyeon , Jing Kaipeng , Shin Soyeon , Kim Soyeon , Heo Jun-Young , Kweon Gi-Ryang , Park Seung-Kiel , Wu Tong , Park Jong-Il , Lim Kyu
Published: August 2015

The anticancer properties and mechanism of action of omega-3 polyunsaturated fatty acids (ω3-PUFAs) have been demonstrated in several cancers; however, the mechanism in lung cancer remains unclear. Here, we show that docosahexaenoic acid (DHA), aω3-PUFA, induced apoptosis and autophagy in non-small cell lung cancer (NSCLC) cells. DHA-induced cell death was accompanied by AMP-activated protein kinase (AMPK) activation and inactivated phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling. Knocking down AMPK and overexpressing Akt increased mTOR activity and attenuated DHA-induced cell death, suggesting that DHA induces cell death via AMPK- and Akt-regulated mTOR inactivation. This was confirmed in Fat-1 transgenic mice, which produceω3-PUFAs. Lewis lung cancer (LLC) tumor cells implanted into Fat-1 mice showed slower growth, lower phospho-Akt levels, and higher levels of apoptosis and autophagy than cells implanted into wild-type mice. Taken together, these data suggest that DHA-induced apoptosis and autophagy in NSCLC cells are associated with AMPK activation and PI3K/Akt inhibition, which in turn lead to suppression of mTOR; thusω3-PUFAs may be utilized as potential therapeutic agents for NSCLC treatment.
Oxidative Stress Alters miRNA and Gene Expression Profiles in Villous First Trimester Trophoblasts
Authors: Cross Courtney E. , Tolba Mai F. , Rondelli Catherine M. , Xu Meixiang , Abdel-Rahman Sherif Z.
Published: August 2015

The relationship between oxidative stress and miRNA changes in placenta as a potential mechanism involved in preeclampsia (PE) is not fully elucidated. We investigated the impact of oxidative stress on miRNAs and mRNA expression profiles of genes associated with PE in villous 3A first trimester trophoblast cells exposed to H2O2at 12 different concentrations (0-1 mM) for 0.5, 4, 24, and 48 h. Cytotoxicity, determined using the SRB assay, was used to calculate the IC50of H2O2. RNA was extracted after 4 h exposure to H2O2for miRNA and gene expression profiling. H2O2exerted a concentration- and time-dependent cytotoxicity on 3A trophoblast cells. Short-term exposure of 3A cells to low concentration of H2O2(5% of IC50) significantly altered miRNA profile as evidenced by significant changes in 195 out of 595 evaluable miRNAs. Tool for annotations of microRNAs (TAM) analysis indicated that these altered miRNAs fall into 43 clusters and 34 families, with 41 functions identified. Exposure to H2O2altered mRNA expression of 22 out of 84 key genes involved in dysregulation of placental development. In conclusion, short-term exposure of villous first trimester trophoblasts to low concentrations of H2O2significantly alters miRNA profile and expression of genes implicated in placental development.
γ‐Secretase Inhibitor Alleviates Acute Airway Inflammation of Allergic Asthma in Mice by Downregulating Th17 Cell Differentiation
Authors: Zhang Weixi , Zhang Xueya , Sheng Anqun , Weng Cuiye , Zhu Tingting , Zhao Wei , Li Changchong
Published: August 2015

T helper 17 (Th17) cells play an important role in the pathogenesis of allergic asthma. Th17 cell differentiation requires Notch signaling. γ‐Secretase inhibitor (GSI) blocks Notch signaling; thus, it may be considered as a potential treatment for allergic asthma. The aim of this study was to evaluate the effect of GSI on Th17 cell differentiation in a mouse model of allergic asthma. OVA was used to induce mouse asthma model in the presence and absence of GSI. GSI ameliorated the development of OVA‐induced asthma, including suppressing airway inflammation responses and reducing the severity of clinical signs. GSI also significantly suppressed Th17‐cell responses in spleen and reduced IL‐17 levels in serum. These findings suggest that GSI directly regulates Th17 responses through a Notch signaling‐dependent pathway in mouse model of allergic asthma, supporting the notion that GSI is a potential therapeutic agent for the treatment of allergic asthma.
Gestational Hypertension and Organophosphorus Pesticide Exposure: A Cross-Sectional Study
Authors: Ledda Caterina , Fiore Maria , Santarelli Lory , Bracci Massimo , Mascali Giuseppe , D’Agati Maria Grazia , Busà Alfredo , Ferrante Margherita , Rapisarda Venerando
Published: August 2015

Hypertension is the most common medical problem encountered during pregnancy, complicating 2-3% of pregnancies. High blood pressure (BP) with diastolic BP ≥ 90 mm Hg and/or systolic BP ≥ 140 mm Hg arising after week 22 of pregnancy and resolving after delivery is defined as gestational hypertension (GHY). The aim of this cross-sectional study was to investigate whether occupational and/or environmental exposure to organophosphorus (OP) pesticide affects GHY. Women at approximately 22 weeks of gestation were recruited. OP pesticide exposure in the first trimester of pregnancy was classified into four categories: no exposure, indirect exposure, domestic exposure, and occupational exposure. Application of the exclusion criteria left 2203 participants (mean age 30.4 ± 11.6 years). Data analysis showed that in women with indirect OP pesticide exposure the incidence of GHY was slightly higher than that in the world population, whereas domestic exposure involved a 7% increase and occupational exposure a 12% increase. Analysis of the pesticides used by participants highlighted a possible role for malathion and diazinon (adjusted OR 1.09 and 1.14, resp.). Further investigation of exposed workers and the general population is clearly warranted given the broad diffusion of OP pesticides and their possible public health impact, maybe by including a wider range of health outcomes.
Heterogeneity of Genetic Damage in Cervical Nuclei and Lymphocytes in Women with Different Levels of Dysplasia and Cancer-Associated Risk Factors
Authors: Alvarez-Moya Carlos , Reynoso-Silva Mónica , Canales-Aguirre Alejandro A. , Chavez-Chavez José O. , Castañeda-Vázquez Hugo , Feria-Velasco Alfredo I.
Published: August 2015

The comet assay can be used to assess genetic damage, but heterogeneity in the length of the tails is frequently observed. The aims of this study were to evaluate genetic damage and heterogeneity in the cervical nuclei and lymphocytes from patients with different levels of dysplasia and to determine the risk factors associated with the development of cervical cancer. The study included 97 females who presented with different levels of dysplasia. A comet assay was performed in peripheral blood lymphocytes and cervical epithelial cells. Significant genetic damage (P≤0.05) was observed only in patients diagnosed with nuclei cervical from dysplasia III (NCDIII) and lymphocytes from dysplasia I (LDI). However, the standard deviations of the tail lengths in the cervical nuclei and lymphocytes from patients with dysplasia I were significantly different (P≤0.0001) from the standard deviations of the tail lengths in the nuclei cervical and lymphocytes from patients with DII and DIII (NCDII, NCDIII and LDII, LDIII), indicating a high heterogeneity in tail length. Results suggest that genetic damage could be widely present but only manifested as increased tail length in certain cell populations. This heterogeneity could obscure the statistical significance of the genetic damage.
Electronic Structure, Electronic Charge Density, and Optical Properties Analysis of GdX3 (X = In, Sn, Tl, and Pb) Compounds: DFT Calculations
Authors: Abraham Jisha Annie , Pagare Gitanjali , Sanyal Sankar P.
Published: August 2015

The electronic properties of magnetic cubic AuCu3 type GdX3 (X = In, Sn, Tl, and Pb) have been studied using first principles calculations based on density functional theory. Because of the presence of strong on-site Coulomb repulsion between the highly localized 4f electrons of Gd atoms, we have used LSDA + U approach to get accurate results in the present study. The electronic band structures as well as density of states reveal that the studied compounds show metallic behavior under ambient conditions. The calculated density of states at the Fermi level N(EF) shows good agreement with the available experimental results. The calculated electronic charge density plots show the presence of ionic bonding in all the compounds along with partial covalent bonding except in GdIn3. The complex optical dielectric function’s dispersion and the related optical properties such as refractive indices, reflectivity, and energy-loss function were calculated and discussed in detail.
Synthesis and Catalytic Performances of a Novel Zn-MOF Catalyst Bearing Nickel Chelating Diimine Carboxylate Ligands for Ethylene Oligomerization
Authors: Liu Suyan , Zhang Ying , Huo Quan , He Sasa , Han Yang
Published: August 2015

A novel Zn-MOF[Zn3(OH)2L2] was synthesized from dicarboxylate ligands with diimine groups (1,4-bis(4-CO2HC6H4)-2,3-dimethyl-1,4-diazabutadiene). The physicochemical properties of the material were characterized by a series of technologies including XRD, SEM, and ICP. In order to adapt to the ethylene oligomerization process, a catalyst[Zn3OH2L1Ni2](denoted as Cat.A) possessing active Ni2+centers was prepared by a postsynthetic treatment method using dichloride nickel as a nickel source in this work. For comparison,α-diimine ligands with/without dicarboxylic acid groups reacted with dichloride nickel to obtain homogenous Cat.B and Cat.C, respectively. The effects of reaction parameters, includingn(Al)/n(Ni), temperature, and pressure on the oligomerization activities and oligomers distribution were investigated. The results demonstrated that all of catalysts used with diethylaluminum chloride were active for the ethylene oligomerization. Among them, Cat.A and Cat.B showed higher catalytic activities and higher selectivities to low-carbonα-olefins at atmospheric pressure. The Cat.A exhibited the optimal catalytic activity [6.7 × 105 g/(mol·Ni·h·atm)] for C4 (91.8%) under the conditions of Al/Ni = 1500,P= 1.0 atm, T = 20°C. In addition, Cat.A and Cat.B presented large amount of ethylene polymer, while Cat.C had a higher catalytic activity of ethylene oligomerization at high pressure.
Numerical and Experimental Study on Energy Performance of Photovoltaic-Heat Pipe Solar Collector in Northern China
Authors: Chen Hongbing , Chen Xilin , Chu Sai , Zhang Lei , Xiong Yaxuan
Published: August 2015

Several studies have found that the decrease of photovoltaic (PV) cell temperature would increase the solar-to-electricity conversion efficiency. Water type PV/thermal (PV/T) system was a good choice but it could become freezing in cold areas of Northern China. This paper proposed a simple combination of common-used PV panel and heat pipe, called PV-heat pipe (PV-HP) solar collector, for both electrical and thermal energy generation. A simplified one-dimensional steady state model was developed to study the electrical and thermal performance of the PV-HP solar collector under different solar radiations, water flow rates, and water temperatures at the inlet of manifold. A testing rig was conducted to verify the model and the testing data matched very well with the simulation values. The results indicated that the thermal efficiency could be minus in the afternoon. The thermal and electrical efficiencies decreased linearly as the inlet water temperature and water flow rate increased. The thermal efficiency increased while the electrical efficiency decreased linearly as the solar radiation increased.
Rat Nasal Respiratory Mucosa-Derived Ectomesenchymal Stem Cells Differentiate into Schwann-Like Cells Promoting the Differentiation of PC12 Cells and Forming MyelinIn Vitro
Authors: Zhang Jian , Gao Xin , Zou Hongjun , Liu Jinbo , Zhang Zhijian
Published: August 2015

Schwann cell (SC) transplantation as a cell-based therapy can enhance peripheral and central nerve repair experimentally, but it is limited by the donor site morbidity for clinical application. We investigated weather respiratory mucosa stem cells (REMSCs), a kind of ectomesenchymal stem cells (EMSCs), isolated from rat nasal septum can differentiate into functional Schwann-like cells (SC-like cells). REMSCs proliferated quicklyin vitroand expressed the neural crest markers (nestin, vimentin, SOX10, and CD44). Treated with a mixture of glial growth factors for 7 days, REMSCs differentiated into SC-like cells. The differentiated REMSCs (dREMSCs) exhibited a spindle-like morphology similar to SC cells. Immunocytochemical staining and Western blotting indicated that SC-like cells expressed the glial markers (GFAP, S100β, Galc, and P75) and CNPase. When cocultured with dREMSCs for 5 days, PC12 cells differentiated into mature neuron-like cells with long neurites. More importantly, dREMSCs could form myelin structures with the neurites of PC12 cells at 21 daysin vitro. Our data indicated that REMSCs, a kind of EMSCs, could differentiate into SC-like cells and have the ability to promote the differentiation of PC12 cells and form myelinin vitro.