bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal diabetes-induced biochemical changes in distinctive layers of mouse retina
Authors: Aboualizadeh Ebrahim , Sorenson Christine M. , Schofield Alex J. , Unger Miriam , Sheibani Nader , Hirschmugl Carol J.
Published: January 2018

To discover the mechanisms underlying the progression of diabetic retinopathy (DR), a more comprehensive understanding of the biomolecular processes in individual retinal cells subjected to hyperglycemia is required. Despite extensive studies, the changes in the biochemistry of retinal layers during the development of DR are not well known. In this study, we aimed to determine a more detailed understanding of the natural history of DR in Akita/+ (type 1 diabetes model) male mice with different duration of diabetes. Employing label-free spatially resolved Fourier transform infrared (FT-IR) chemical imaging engaged with multivariate analysis enabled us to identify temporal-dependent reproducible biomarkers of the individual retinal layers from mice with 6 weeks,12 weeks, 6 months, and 10 months of age. We report, for the first time, the nature of the biochemical alterations over time in the biochemistry of distinctive retinal layers namely photoreceptor retinal layer (PRL), inner nuclear layer (INL), and plexiform layers (OPL, IPL). Moreover, we present the molecular factors associated with the changes in the protein structure and cellular lipids of retinal layers induced by different duration of diabetes. Our paradigm provides a new conceptual framework for a better understanding of the temporal cellular changes underlying the progression of DR.
Identification of a membrane-less compartment regulating invadosome function and motility
Authors: Sala Kristyna , Raimondi Andrea , Tonoli Diletta , Tacchetti Carlo , de Curtis Ivan
Published: January 2018

Depletion of liprin-α1, ERC1 or LL5 scaffolds inhibits extracellular matrix degradation by invasive cells. These proteins co-accumulate near invadosomes in NIH-Src cells, identifying a novel invadosome–associated compartment distinct from the core and adhesion ring of invadosomes. Depletion of either protein perturbs the organization of invadosomes without influencing the recruitment of MT1-MMP metalloprotease. Liprin-α1 is not required for de novo formation of invadosomes after their disassembly by microtubules and Src inhibitors, while its depletion inhibits invadosome motility, thus affecting matrix degradation. Fluorescence recovery after photobleaching shows that the invadosome–associated compartment is dynamic, while correlative light immunoelectron microscopy identifies bona fide membrane–free invadosome–associated regions enriched in liprin-α1, which is virtually excluded from the invadosome core. The results indicate that liprin-α1, LL5 and ERC1 define a novel dynamic membrane-less compartment that regulates matrix degradation by affecting invadosome motility.
Umbilical cord extracts improve osteoporotic abnormalities of bone marrow-derived mesenchymal stem cells and promote their therapeutic effects on ovariectomised rats
Authors: Saito Akira , Nagaishi Kanna , Iba Kousuke , Mizue Yuka , Chikenji Takako , Otani Miho , Nakano Masako , Oyama Kazusa , Yamashita Toshihiko , Fujimiya Mineko
Published: January 2018

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are the most valuable source of autologous cells for transplantation and tissue regeneration to treat osteoporosis. Although BM-MSCs are the primary cells responsible for maintaining bone metabolism and homeostasis, their regenerative ability may be attenuated in postmenopausal osteoporosis patients. Therefore, we first examined potential abnormalities of BM-MSCs in an oestrogen-deficient rat model constructed by ovariectomy (OVX-MSCs). Cell proliferation, mobilisation, and regulation of osteoclasts were downregulated in OVX-MSCs. Moreover, therapeutic effects of OVX-MSCs were decreased in OVX rats. Accordingly, we developed a new activator for BM-MSCs using human umbilical cord extracts, Wharton’s jelly extract supernatant (WJS), which improved cell proliferation, mobilisation and suppressive effects on activated osteoclasts in OVX-MSCs. Bone volume, RANK and TRACP expression of osteoclasts, as well as proinflammatory cytokine expression in bone tissues, were ameliorated by OVX-MSCs activated with WJS (OVX-MSCs-WJ) in OVX rats. Fusion and bone resorption activity of osteoclasts were suppressed in macrophage-induced and primary mouse bone marrow cell-induced osteoclasts via suppression of osteoclast-specific genes, such as Nfatc1, Clcn7, Atp6i and Dc-stamp, by co-culture with OVX-MSCs-WJ in vitro. In this study, we developed a new activator, WJS, which improved the functional abnormalities and therapeutic effects of BM-MSCs on postmenopausal osteoporosis.
Noise-induced bistability in the fate of cancer phenotypic quasispecies: a bit-strings approach
Authors: Sardanyés Josep , Alarcón Tomás
Published: January 2018

Tumor cell populations are highly heterogeneous. Such heterogeneity, both at genotypic and phenotypic levels, is a key feature during tumorigenesis. How to investigate the impact of this heterogeneity in the dynamics of tumors cells becomes an important issue. Here we explore a stochastic model describing the competition dynamics between a pool of heterogeneous cancer cells with distinct phenotypes and healthy cells. This model is used to explore the role of demographic fluctuations on the transitions involving tumor clearance. Our results show that for large population sizes, when demographic fluctuations are negligible, there exists a sharp transition responsible for tumor cells extinction at increasing tumor cells’ mutation rates. This result is consistent with a mean field model developed for the same system. The mean field model reveals only monostability scenarios, in which either the dominance of the tumor cells or the dominance of the healthy cells is found. Interestingly, the stochastic model shows that for small population sizes the monostability behavior disappears, involving the presence of noise-induced bistability. The impact of the initial populations of cells in the fate of the cell populations is investigated, as well as the transient times towards the healthy and the cancer states.
Chinese olive extract ameliorates hepatic lipid accumulation in vitro and in vivo by regulating lipid metabolism
Authors: Yeh Yu-Te , Cho Yan-Yu , Hsieh Shu-Chen , Chiang An-Na
Published: January 2018

Chinese olive contains plenty of polyphenols, which possess a wide range of biological actions. In this study, we aimed to investigate the role of the ethyl acetate fraction of Chinese olive fruit extract (CO-EtOAc) in the modulation of lipid accumulation in vitro and in vivo. In cellular studies, CO-EtOAc attenuated oleic acid-induced lipid accumulation; we then elucidated the molecular mechanisms of CO-EtOAc in FL83B mouse hepatocytes. CO-EtOAc suppressed the mRNA levels of fatty acid transporter genes (CD36 and FABP) and lipogenesis genes (SREBP-1c, FAS, and ACC1), but upregulated genes that govern lipolysis (HSL) and lipid oxidation (PPARα, CPT-1, and ACOX). Moreover, CO-EtOAc increased the protein expression of phosphorylated AMPK, ACC1, CPT-1, and PPARα, but downregulated the expression of mature SREBP-1c and FAS. AMPK plays an essential role in CO-EtOAc-mediated amelioration of lipid accumulation. Furthermore, we confirmed that CO-EtOAc significantly inhibited body weight gain, epididymal adipose tissue weight, and hepatic lipid accumulation via regulation of the expression of fatty acid transporter, lipogenesis, and fatty acid oxidation genes and proteins in C57BL/6 mice fed a 60% high-fat diet. Therefore, Chinese olive fruits may have the potential to improve the metabolic abnormalities associated with fatty liver under high fat challenge.
Amygdala-orbitofrontal structural and functional connectivity in females with anxiety disorders, with and without a history of conduct disorder
Authors: Lindner Philip , Flodin Pär , Larm Peter , Budhiraja Meenal , Savic-Berglund Ivanka , Jokinen Jussi , Tiihonen Jari , Hodgins Sheilagh
Published: January 2018

Conduct disorder (CD) and anxiety disorders (ADs) are often comorbid and both are characterized by hyper-sensitivity to threat, and reduced structural and functional connectivity between the amygdala and orbitofrontal cortex (OFC). Previous studies of CD have not taken account of ADs nor directly compared connectivity in the two disorders. We examined three groups of young women: 23 presenting CD and lifetime AD; 30 presenting lifetime AD and not CD; and 17 with neither disorder (ND). Participants completed clinical assessments and diffusion-weighted and resting-state functional MRI scans. The uncinate fasciculus was reconstructed using tractography and manual dissection, and structural measures extracted. Correlations of resting-state activity between amygdala and OFC seeds were computed. The CD + AD and AD groups showed similarly reduced structural integrity of the left uncinate compared to ND, even after adjusting for IQ, psychiatric comorbidity, and childhood maltreatment. Uncinate integrity was associated with harm avoidance traits among AD-only women, and with the interaction of poor anger control and anxiety symptoms among CD + AD women. Groups did not differ in functional connectivity. Reduced uncinate integrity observed in CD + AD and AD-only women may reflect deficient emotion regulation in response to threat, common to both disorders, while other neural mechanisms determine the behavioral response.
v-Src-driven transformation is due to chromosome abnormalities but not Src-mediated growth signaling
Authors: Honda Takuya , Morii Mariko , Nakayama Yuji , Suzuki Ko , Yamaguchi Noritaka , Yamaguchi Naoto
Published: January 2018

v-Src is the first identified oncogene product and has a strong tyrosine kinase activity. Much of the literature indicates that v-Src expression induces anchorage-independent and infinite cell proliferation through continuous stimulation of growth signaling by v-Src activity. Although all of v-Src-expressing cells are supposed to form transformed colonies, low frequencies of v-Src-induced colony formation have been observed so far. Using cells that exhibit high expression efficiencies of inducible v-Src, we show that v-Src expression causes cell-cycle arrest through p21 up-regulation despite ERK activation. v-Src expression also induces chromosome abnormalities and unexpected suppression of v-Src expression, leading to p21 down-regulation and ERK inactivation. Importantly, among v-Src-suppressed cells, only a limited number of cells gain the ability to re-proliferate and form transformed colonies. Our findings provide the first evidence that v-Src-driven transformation is attributed to chromosome abnormalities, but not continuous stimulation of growth signaling, possibly through stochastic genetic alterations.
Highly efficient and stable inverted perovskite solar cell employing PEDOT:GO composite layer as a hole transport layer
Authors: Yu Jae Choul , Hong Ji A , Jung Eui Dae , Kim Da Bin , Baek Soo-Min , Lee Sukbin , Cho Shinuk , Park Sung Soo , Choi Kyoung Jin , Song Myoung Hoon
Published: January 2018

The beneficial use of a hole transport layer (HTL) as a substitution for poly(3,4-ethlyenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) is regarded as one of the most important approaches for improving the stability and efficiency of inverted perovskite solar cells. Here, we demonstrate highly efficient and stable inverted perovskite solar cells by applying a GO-doped PEDOT:PSS (PEDOT:GO) film as an HTL. The high performance of this solar cell stems from the excellent optical and electrical properties of the PEDOT:GO film, including a higher electrical conductivity, a higher work function related to the reduced contact barrier between the perovskite layer and the PEDOT:GO layer, enhanced crystallinity of the perovskite crystal, and suppressed leakage current. Moreover, the device with the PEDOT:GO layer showed excellent long-term stability in ambient air conditions. Thus, the enhancement in the efficiency and the excellent stability of inverted perovskite solar cells are promising for the eventual commercialization of perovskite optoelectronic devices.
Depressive mood ratings are reduced by MDMA in female polydrug ecstasy users homozygous for the l-allele of the serotonin transporter
Authors: Kuypers K. P. C. , de la Torre R. , Farre M. , Xicota L. , de Sousa Fernandes Perna E. B. , Theunissen E. L. , Ramaekers J. G.
Published: January 2018

MDMA exerts its main effects via the serotonergic system and the serotonin transporter. The gene coding for this transporter determines the expression rate of the transporter. Previously it was shown that healthy individuals with the short allelic variant (‘s-group’) of the 5-HTTLPR-polymorphism displayed more anxiety and negative mood, and had a lower transcriptional efficiency compared to individuals who are homozygous for the l-allele (‘l-group’). The present study aimed to investigate the role of the 5-HTTLPR polymorphism in MDMA-induced mood effects. Four placebo-controlled, within-subject studies were pooled, including in total 63 polydrug ecstasy users (Ns-group = 48; Nl-group = 15) receiving MDMA 75 mg and placebo on two test days, separated by minimally 7 days. Mood was assessed by means of the Profile of Mood States. Findings showed that MDMA induced –independent of sex- a positive mood state, and as a side effect also increased two negative affect states, anxiety and confusion. Anxiety ratings were higher in the l-group and independent of treatment or sex. Depression ratings were lowered by MDMA in the female l-group. Findings indicate that the MDMA-induced reduction in self-rated depressive feelings is sex- and genotype-dependent, with females homozygous for the l-allele showing this beneficial effect.
Generation and Characterization of Alloantigen-Specific Regulatory T Cells For Clinical Transplant Tolerance
Authors: Mathew James M. , Voss Jessica H. , McEwen Scott T. , Konieczna Iwona , Chakraborty Arjun , Huang Xuemei , He Jie , Gallon Lorenzo , Kornbluth Richard S. , Leventhal Joseph R.
Published: January 2018

Donor-specific CD4+CD127−CD25+FOXP3+ regulatory T cells (AgTregs) have the potential to induce clinical transplant tolerance; however, their expansion ex vivo remains challenging. We optimized a novel expansion protocol to stimulate donor-specific Tregs using soluble 4-trimer CD40 ligand (CD40L)-activated donor B cells that expressed mature antigen-presenting cell markers. This avoided the use of CD40L-expressing stimulator cells that might otherwise result in potential cellular contamination. Purified allogeneic “recipient” CD4+CD25+ Tregs were stimulated on days 0 and 7 with expanded “donor” B cells in the presence of IL-2, TGFβ and sirolimus (SRL). Tregs were further amplified by polyclonal stimulation with anti-CD3/CD28 beads on day 14 without SRL, and harvested on day 21, with extrapolated fold expansion into the thousands. The expanded AgTregs maintained expression of classical Treg markers including demethylation of the Treg-specific demethylated region (CNS2) and also displayed constricted TcR repertoire. We observed AgTregs more potently inhibited MLR than polyclonally expanded Tregs and generated new Tregs in autologous responder cells (a measure of infectious tolerance). Thus, an optimized and more clinically applicable protocol for the expansion of donor-specific Tregs has been developed.
Exendin-4–encapsulated dissolving microneedle arrays for efficient treatment of type 2 diabetes
Authors: Fakhraei Lahiji Shayan , Jang Yoojung , Huh Inyoung , Yang Huisuk , Jang Mingyu , Jung Hyungil
Published: January 2018

Dissolving microneedles (DMNs) are microscopic needles capable of delivering encapsulated compounds and releasing them into the skin in a minimally invasive manner. Most studies indicate that encapsulating therapeutics in DMNs is an efficacious approach; however, the importance of evaluating the activity of encapsulated compounds, during the fabrication process, has not been examined in detail. Conducting an analysis of thermal, chemical, and physical stress factors, including temperature, pH, and the interaction of the polymer and therapeutics mixture during preparation, is essential for retaining the activity of encapsulated therapeutics during and after fabrication. Here, we optimised the thermal, chemical, and physical parameters for the fabrication of exendin-4 (Ex-4)–encapsulated DMNs (Ex-4 DMNs). Ex-4, a peptide agonist of glucagon-like peptide (GLP) receptor, is used for glycaemic control in patients with type 2 diabetes. Our findings indicate that optimising the parameters involved in DMN fabrication retained the activity of Ex-4 by up to 98.3 ± 1.5%. Ex-4 DMNs reduced the blood-glucose level in diabetic mice with efficiency similar to that of a subcutaneous injection. We believe that this study paves way for the commercialisation of an efficient and minimally invasive treatment for patients with type 2 diabetes.
The use of Hall technique preformed metal crowns by specialist paediatric dentists in the UK
Authors: Roberts A , McKay A , Albadri S
Published: January 2018

Background Hall technique preformed metal crowns (HTPMCs) have been increasing in use recently, but little is currently known about their use by specialists.

Aim To investigate the views and usage of HTPMCs by UK specialist paediatric dentists.

Design This was a prospective questionnaire-based study, distributed online to all specialists on the British Society of Paediatric Dentistry email list between July and September 2014.

Results Ninety-four questionnaires were completed. The majority of respondents, 65% (61) worked in teaching hospitals, followed by community dental services, 37% (35). Ninety-six percent (89) reported that they used HTPMCs in their practice. Fifty-eight percent (54) used HTPMCs as a treatment option for restoring symptomless carious primary molars, and 15% (14) only when unable to provide conventional restoration. Twenty-three percent (21) used HTPMCs as the treatment of choice. Only 4% (4) of respondents never used them. Sixty percent (53) had been using HTPMCs for over five years. Seventy-six percent (68) would consider placing HTPMCs under inhalation sedation, and 26% (23) under general anaesthesia. Over 90% (85) believed that HTPMCs are suitable for undergraduate teaching, general practice, postgraduate training and specialist practice.

Conclusion HTPMCs are widely used among specialist paediatric dentists in the UK.
Porous CoP nanosheets converted from layered double hydroxides with superior electrochemical activity for hydrogen evolution reactions at wide pH ranges
Authors: Zeng Yifan , Wang Yanyong , Huang Gen , Chen Chen , Huang Liangliang , Chen Ru , Wang Shuangyin
Published: January 2018

Simple etching and phosphidation of LDHs to form porous CoP for superior electrocatalyst HER performance over wide pH ranges.
Understanding interface (odd–even) effects in charge tunneling using a polished EGaIn electrode
Authors: Chen Jiahao , Giroux Thomas J. , Nguyen Yen , Kadoma Atte A. , Chang Boyce S. , VanVeller Brett , Thuo Martin M.
Published: January 2018

Charge transport across large area molecular tunneling junctions is widely studied due to its potential in the development of quantum electronic devices.
Atomistic insights into the nanofluid transport through an ultra-confined capillary
Authors: Wang Xiao , Zhang Zhiliang , Torsæter Ole , He Jianying
Published: January 2018

Nanofluid or nanoparticle (NP) transport in confined channels is of great importance for many biological and industrial processes.
A self-assembled CdSe QD–organogel hybrid: photophysical and thermoresponsive properties
Authors: Chatterjee Sayantan , Kuppan Balamurugan , Maitra Uday
Published: January 2018

Synthesis and reversible thermoresponsive luminescence behaviour of a self-assembled QD–organogel hybrid derived from a facially amphiphilic bile acid.
Functionalization of fluorodinitroethylamino derivatives based on azole: a new family of insensitive energetic materials
Authors: Wang Weixia , Cheng Guangbin , Xiong Hualin , Yang Hongwei
Published: January 2018

In this study, we report the synthesis of a new family of fluorodinitroethyl-substituted aminoazole derivatives, which might be of interest for applications as insensitive energetic materials.
Synthesis and characterization of Cu3N nanoparticles using pyrrole-2-carbaldpropyliminato Cu(ii) complex and Cu(NO3)2as single-source precursors: the search for an ideal precursor
Authors: Sithole Rudo K. , Machogo Lerato F. E. , Airo Mildred A. , Gqoba Siziwe S. , Moloto Makwena J. , Shumbula Poslet , Van Wyk Juanita , Moloto Nosipho
Published: January 2018

Herein, we report the synthesis and characterization of Cu3N nanocrystals using two single-source precursors, bis (pyrrole-2-carbalpropyliminato) Cu(ii) (PPC) and Cu(NO3)2·3H2O.
Curvature-dependent flexible light emission from layered gallium selenide crystals
Authors: Chuang Ching-An , Lin Min-Han , Yeh Bo-Xian , Ho Ching-Hwa
Published: January 2018

Curvature-dependent luminescence enhancement and bandgap shift of 2D layered GaSe under upward bending have been clearly analyzed and demonstrated.
Bimetallic M/N/C catalysts prepared from π-expanded metal salen precursors toward an efficient oxygen reduction reaction
Authors: Onoda Akira , Tanaka Yuta , Matsumoto Koki , Ito Minoru , Sakata Takao , Yasuda Hidehiro , Hayashi Takashi
Published: January 2018

Bimetallic metal and nitrogen-containing carbon (M/N/C) catalysts were prepared by pyrolysis of a mixture of carbon support and π-expanded Fe(salen) and Cu(salen) precursors. The bimetallic catalyst promotes efficient four-electron reduction of dioxygen.
Photocatalytic hydrogen generation from a visible-light responsive metal–organic framework system: the impact of nickel phosphide nanoparticles
Authors: Kampouri Stavroula , Nguyen Tu N. , Ireland Christopher P. , Valizadeh Bardiya , Ebrahim Fatmah Mish , Capano Gloria , Ongari Daniele , Mace Amber , Guijarro Nestor , Sivula Kevin , Sienkiewicz Andrzej , Forró László , Smit Berend , Stylianou Kyriakos C.
Published: January 2018

We showcase the key role of the co-catalyst when combined with MIL-125-NH2 towards the photocatalytic H2 generation.
Do imaging techniques add real value to the development of better post-Li-ion batteries?
Authors: Conder Joanna , Marino Cyril , Novák Petr , Villevieille Claire
Published: January 2018

Imaging techniques are increasingly used to study Li-ion batteries and, in particular, post-Li-ion batteries such as Li–S batteries, Na-ion batteries, Na–air batteries and all-solid-state batteries. Herein, we review recent advances in the field made through the use of these techniques.
Prognostic roles of signal transducers and activators of transcription family in human breast cancer
Authors: Wang Shuntao , Yu Lili , Shi Wei , Li Xueqin , Yu Lixiu
Published: January 2018

Signal transducers and activators of transcription (STAT) family are critical transcription factors, which have been proved as prognostic predictors for a number of cancers. However, the prognostic roles of STAT family in breast cancer patients remain in dispute. In the present study, we mined the ‘Kaplan–Meier plotter’ (KM plotter) online database to explore the prognostic roles of STAT family mRNA expression in breast cancer including overall survival (OS), progression-free survival (PFS), as well as post-progression survival (PPS). The results suggest high mRNA expression of all the individual STATs, except STAT1 and STAT2, are significantly associated with favorable OS in breast cancer patients; high STAT1 mRNA expression is significantly associated with worse RFS and all the other individual STATs, except STAT3, are significantly associated with better RFS in breast cancer patients; only high STAT5b mRNA expression is significantly related to better PPS in breast cancer patients. Additionally, we explored the prognostic values of individual STATs in other clinicopathological features, such as pathological grades, estrogen receptor (ER) status and so on. The results suggest, except STAT2 and STAT6, high mRNA expression of STATs is related to a favorable prognosis especially for high pathological grade; high STAT5 mRNA expression indicates a favorable prognosis no matter under ER positive or negative status; high STAT4 mRNA expression suggests a favorable prognosis under human epidermal growth factor receptor 2 (HER2) negative status. Our results indicate that individual STATs, except STAT1 and STAT2, may act as a favorable prognostic biomarker in breast cancer. Nevertheless, further investigations on a larger population are warranted.
Remote Microphone System Use at Home: Impact on Caregiver Talk
Authors: Benítez-Barrera Carlos R. , Angley Gina P. , Tharpe Anne Marie
Published: January 2018

Purpose

The purpose of this study was to investigate the effects of home use of a remote microphone system (RMS) on the spoken language production of caregivers with young children who have hearing loss.

Method

Language Environment Analysis recorders were used with 10 families during 2 consecutive weekends (RMS weekend and No-RMS weekend). The amount of talk from a single caregiver that could be made accessible to children with hearing loss when using an RMS was estimated using Language Environment Analysis software. The total amount of caregiver talk (close and far talk) was also compared across both weekends. In addition, caregivers' perceptions of RMS use were gathered.

Results

Children, with the use of RMSs, could potentially have access to approximately 42% more words per day. In addition, although caregivers produced an equivalent number of words on both weekends, they tended to talk more from a distance when using the RMS than when not. Finally, caregivers reported positive perceived communication benefits of RMS use.

Conclusions

Findings from this investigation suggest that children with hearing loss have increased access to caregiver talk when using an RMS in the home environment. Clinical implications and future directions for research are discussed.
Low‐cost message‐driven frequency‐hopping scheme based on slow frequency‐hopping
Authors: Ning Ben , Zhong Da , Guan Lei , Li Zan
Published: January 2018

This study presents a novel message‐driven frequency‐hopping (MDFH) scheme leveraging slow frequency‐hopping (FH). Since the typical MDFH scheme requires a large amount of detectors to obtain the information that is transmitted through carrier frequency selection, the authors aim at a low‐cost MDFH implementation in this study. The basic idea of the proposed FH scheme is to transmit a part of information through the hop rate instead of the carrier frequency selection of an FH signal, which results in reduced hardware cost and better system efficiency. Moreover, a collision‐free multi‐carrier extension is also introduced in this study. The lower bound on the bit error rate (BER) performance of the proposed scheme is analysed and is verified by numerical results. The numerical results also reveal that the proposed scheme has a better BER and throughput performances than the typical MDFH systems at a low signal‐to‐noise ratio.
Resource allocation optimisation for delay‐sensitive traffic in energy harvesting cloud radio access network
Authors: Duan Sijing , Chen Zhigang , Zhang Deyu
Published: January 2018

In this study, the authors study a sustainable resource allocation scheme for delay‐sensitive applications in an energy harvesting (EH)‐cloud radio access network (CRAN). The authors formulate an optimisation problem to maximise the user equipment (UE) utility and provide them with strong delay‐guarantee by jointly considering the stochastic EH process, dynamic wireless channel state. By using the Lyapunov stochastic network optimisation technique combined with virtual queues, the authors decompose the formulated problem into four sub‐problems, including channel allocation, data dropping, UE request scheduling and energy management. Based on the solutions of these sub‐problems, a UE optimal resource allocation algorithm is proposed to maximise UE utility while guaranteeing the delay bound and the sustainability of remote radio heads. Furthermore, this algorithm does not require any prior statistical information of the system, e.g. EH process and channel state. Both theoretical analyses and simulation results demonstrate that the proposed algorithm can achieve close‐to‐optimal UE utility, bounded data buffer, delay‐guarantee, and required battery capacity for the operation of the CRAN.
Dynamic resource allocation for uplink non‐orthogonal multiple access systems
Authors: Lv Guocheng , Li Xunan , Shang Ruibo , Xue Ping , Jin Ye
Published: January 2018

This study investigates a problem of resource allocation for an uplink multi‐carrier non‐orthogonal multiple access (NOMA) system. To provide a general resource allocation problem, the order of successive interference cancellation (SIC), subcarrier assignment and power allocation are all considered as the optimisation variables of interest, with the objective of maximising the weighted sum rate under the transmit power constraint of each user equipment (UE). Firstly, a novel optimal SIC order is proposed based on the inherent structure of the uplink NOMA system. Then, with the optimal SIC order, the Lagrange dual method is employed to solve the joint subcarrier assignment and power allocation problem in an asymptotically optimal manner. In addition, an optimal solution of power allocation with a fixed subcarrier assignment is presented. In light of the optimal power allocation, a tight upper bound of the uplink NOMA system is developed by relaxing the number of multiplexed UEs on each subcarrier. Simulation results show that the proposed algorithm outperforms conventional orthogonal multiple access schemes and other static NOMA schemes, and as a benchmark, the upper bound reveals that multiplexing at most two UEs on each subcarrier is sufficient for the performance improvement.
Approach to delay‐dependent robust stability and stabilisation of delta operator systems with time‐varying delays
Authors: El Aiss Hicham , Rachid Hafsaa , Hmamed Abdelaziz , El Hajjaji Ahmed
Published: January 2018

This study investigates the problem of delay‐dependent stability and stabilisation of uncertain delta operator systems with time‐varying delay. A new model transformation is proposed using a three‐term approximation, which has a smaller approximation error than the existing methods based on one or two terms. On the basis of scaled small gain theorem (scaled small gain) and an appropriate Lyapunov–Krasovskii functional, a new stability criterion is proposed in terms of linear matrix inequalities. Finally, numerical examples are presented to illustrate the effectiveness of the proposed method.
Boundary vibration control for a flexible Timoshenko robotic manipulator
Authors: He Xiuyu , He Wei , Qin Hui , Sun Changyin
Published: January 2018

The authors investigate the dynamic modelling problem and the active vibration control design problem for a flexible Timoshenko robotic manipulator in this study. For the practical robotic manipulator, the authors analyse the dynamic characteristic considering the shear deformation and elastic deflection of the flexible arm link and describe this flexible system with a coupled partial differential equation and ordinary differential equations (PDE–ODEs) model. Furthermore, the authors design the active vibration control and disturbance observers to solve the vibration problem of the flexible robotic manipulator under the external disturbances, namely, to reduce the shear deformation and the deflection of the flexible Timoshenko link. Besides, the manipulator is driven to track the given angular position with an active angular controller, simultaneously. The effectiveness of the designed vibration control laws is analysed by the theoretical analysis and verified by the numerical simulation.
Performance improvement of pilot‐assisted power allocation in vehicular small cells with preprocessing under measurement errors
Authors: Alizadeh Sajjad , Saadat Reza
Published: January 2018

The authors consider the pilot‐assisted power allocation of the wireless backhaul link presented in some recent literatures in the vehicular heterogeneous small cell networks under the imperfect measurement. To implement aforementioned algorithm, it is essential to measure the received power on the backhaul link. However, due to the dynamic feature of the wireless backhaul in the vehicular small cells, the perfect measurement is approximately impossible in practice. Moreover, in spite of the signal‐to‐interference plus noise ratio (SINR) balancing property, the pilot‐assisted algorithm is significantly sensitive to the measurement error. Accordingly, in this study at first the authors formulate the measurement error of the uplink received power in the macro base stations and then propose a preprocessing‐based algorithm to reduce the effects of the imperfect measurement on the SINR balancing of the pilot‐based algorithm. Specifically, in two‐layer small cell network considered in this work, the authors derive a modification coefficient proportional to the maximum percentage of the measurement error in a layer by solving an optimisation problem and utilise it in another layer before transmission. Simulation results demonstrate the effectiveness of the proposed scheme in comparison with the existing algorithm in terms of the SINR balancing especially in high measurement error.
Zero‐sequence voltage injected fault tolerant scheme for multiple open circuit faults in reduced switch count‐based MLDCL inverter
Authors: Vemuganti Hari Priya , Sreenivasarao Dharmavarapu , Siva Kumar Ganjikunta
Published: January 2018

Neutral shifting (NS) is a popular scheme to achieve fault tolerance operation (FTO) of multilevel inverters (MLIs) such as cascaded H‐bridge (CHB). This fault tolerance scheme (FTS) can be realised with/without zero‐sequence voltage injection. Among these, NS with zero‐sequence injection FTS is relatively easier to implement. However, this scheme is not generalised for multiple open‐circuit faults. Moreover, NS‐FTS schemes are not directly applicable for fault tolerance of reduced switch count (RSC)‐MLIs, as these inverters have limited redundancies. Therefore in this study, FTO for RSC‐based multilevel dc‐link (MLDCL) inverter using NS zero‐sequence injection FTS is proposed for simultaneous failure of multiple switch faults. Generalised mathematical equations are derived to calculate the magnitude and phase angle of injected zero‐sequence voltage for obtaining balanced line voltages with uniform power sharing among all healthy units. The proposed generalised NS‐FTS with zero‐sequence injection is implemented on three‐phase 15‐level MLDCL inverter for various fault conditions. The obtained simulation results are validated experimentally on nine‐level MLDCL inverter.
LC/CL compensation topology and efficiency‐based optimisation method for wireless power transfer
Authors: Yao Yousu , Liu Xiaosheng , Wang Yijie , Xu Dianguo
Published: January 2018

Wireless power transfer (WPT) has attracted a large amount of attention due to its inherent advantages such as convenience, safety, low maintenance, weather proof and so on. Compensation topology is crucial for WPT system due to its function of reducing reactive power and improving system efficiency. Series–series (SS) compensation topology is widely employed due to a simple structure and the characteristic of constant current output (CCO). However, it has three serious drawbacks: high‐voltage stresses on compensation capacitors, poor CCO characteristic under practical situations and significant dependence on coupling coils. This study proposes LC/CL (primary inductor–capacitor and secondary capacitor–inductor) compensation topology to eliminate aforementioned deficiencies of SS. The voltage stresses on compensation capacitors of LC/CL are much lower than those of SS. LC/CL also provides better CCO characteristics in imperfect scenarios. Load current of LC/CL compensated system only increases by 1.89% when the load is reduced by half. In contrast, the load current of SS compensated system increases by 6.87% with identical load reduction. An efficiency‐based optimisation method is proposed for higher end‐to‐end efficiency as well. The validity of the optimisation is justified by both simulation and experiment. The efficiency of the optimised system is about 2% higher than that of a non‐optimised system.
The supernova-regulated ISM
Authors: Käpylä M. J. , Gent F. A. , Väisälä M. S. , Sarson G. R.
Published: January 2018

Context.The forcing of interstellar turbulence, driven mainly by supernova (SN) explosions, is irrotational in nature, but the development of significant amounts of vorticity and helicity, accompanied by large-scale dynamo action, has been reported.

Aim.Several earlier investigations examined vorticity production in simpler systems; here all the relevant processes can be considered simultaneously. We also investigate the mechanisms for the generation of net helicity and large-scale flow in the system.

Methods.We use a three-dimensional, stratified, rotating and shearing local simulation domain of the size 1 × 1 × 2 kpc3, forced with SN explosions occurring at a rate typical of the solar neighbourhood in the Milky Way. In addition to the nominal simulation run with realistic Milky Way parameters, we vary the rotation and shear rates, but keep the absolute value of their ratio fixed. Reversing the sign of shear vs. rotation allows us to separate the rotation- and shear-generated contributions.

Results.As in earlier studies, we find the generation of significant amounts of vorticity, the rotational flow comprising on average 65% of the total flow. The vorticity production can be related to the baroclinicity of the flow, especially in the regions of hot, dilute clustered supernova bubbles. In these regions, the vortex stretching acts as a sink of vorticity. In denser, compressed regions, the vortex stretching amplifies vorticity, but remains sub-dominant to baroclinicity. The net helicities produced by rotation and shear are of opposite signs for physically motivated rotation laws, with the solar neighbourhood parameters resulting in the near cancellation of the total net helicity. We also find the excitation of oscillatory mean flows, the strength and oscillation period of which depend on the Coriolis and shear parameters; we interpret these as signatures of the anisotropic-kinetic-α(AKA) effect. We use the method of moments to fit for the turbulent transport coefficients, and findαAKAvalues of the order 3–5 km s−1.

Conclusions.Even in a weakly rotationally and shear-influenced system, small-scale anisotropies can lead to significant effects at large scales. Here we report on two consequences of such effects, namely on the generation of net helicity and on the emergence of large-scale flows by the AKA effect, the latter detected for the first time in a direct numerical simulation of a realistic astrophysical system.
Close-by planets and flares in their host stars
Authors: Lanza A. F.
Published: January 2018

Context. The interaction between the magnetic fields of late-type stars and their close-by planets may produce stellar flares as observed in active binary systems. However, in spite of several claims, conclusive evidence is still lacking.

Aim. We estimate the magnetic energy available in the interaction using analytical models to provide an upper bound to the expected flare energy.

Methods. We investigated three different mechanisms leading to magnetic energy release. The first two can release an energy up to (0.2–1.2) B02R3/μ, where B0 is the surface field of the star, R its radius, and μ the magnetic permeability of the plasma. These two mechanisms operate in young active stars whose coronae have closed magnetic field lines up to the distance of their close-by planets that can trigger the energy release. The third mechanism operates in weakly or moderately active stars with a coronal field with predominantly open field lines at the distance of their planets. The released energy is of the order of (0.002–0.1) B02R3/μ and depends on the ratio of the planetary to the stellar fields, thus allowing an indirect measurement of the former when the latter is known.

Results. We compute the released energy for various separations of the planet and various stellar parameters finding the conditions for the operation of the proposed mechanisms. An application to eight selected systems is presented. Conclusions. The computed energies and dissipation timescales are in agreement with flare observations in the eccentric system HD 17156 and in the circular systems HD 189733 and HD 179949. This kind of star–planet interaction can be unambiguously identified by the higher flaring frequency expected close to periastron in eccentric systems.
Observational properties of massive black hole binary progenitors
Authors: Hainich R. , Oskinova L. M. , Shenar T. , Marchant P. , Eldridge J. J. , Sander A. A. C. , Hamann W.-R. , Langer N. , Todt H.
Published: January 2018

Context. The first directly detected gravitational waves (GW 150914) were emitted by two coalescing black holes (BHs) with masses of ≈ 36 M⊙ and ≈ 29 M⊙. Several scenarios have been proposed to put this detection into an astrophysical context. The evolution of an isolated massive binary system is among commonly considered models.

Aims. Various groups have performed detailed binary-evolution calculations that lead to BH merger events. However, the question remains open as to whether binary systems with the predicted properties really exist. The aim of this paper is to help observers to close this gap by providing spectral characteristics of massive binary BH progenitors during a phase where at least one of the companions is still non-degenerate.

Methods. Stellar evolution models predict fundamental stellar parameters. Using these as input for our stellar atmosphere code (Potsdam Wolf-Rayet), we compute a set of models for selected evolutionary stages of massive merging BH progenitors at different metallicities.

Results. The synthetic spectra obtained from our atmosphere calculations reveal that progenitors of massive BH merger events start their lives as O2-3V stars that evolve to early-type blue supergiants before they undergo core-collapse during the Wolf-Rayet phase. When the primary has collapsed, the remaining system will appear as a wind-fed high-mass X-ray binary. Based on our atmosphere models, we provide feedback parameters, broad band magnitudes, and spectral templates that should help to identify such binaries in the future.

Conclusions. While the predicted parameter space for massive BH binary progenitors is partly realized in nature, none of the known massive binaries match our synthetic spectra of massive BH binary progenitors exactly. Comparisons of empirically determined mass-loss rates with those assumed by evolution calculations reveal significant differences. The consideration of the empirical mass-loss rates in evolution calculations will possibly entail a shift of the maximum in the predicted binary-BH merger rate to higher metallicities, that is, more candidates should be expected in our cosmic neighborhood than previously assumed.
The supermassive black hole coincident with the luminous transient ASASSN-15lh
Authors: Krühler T. , Fraser M. , Leloudas G. , Schulze S. , Stone N. C. , van Velzen S. , Amorin R. , Hjorth J. , Jonker P. G. , Kann D. A. , Kim S. , Kuncarayakti H. , Mehner A. , Nicuesa Guelbenzu A.
Published: January 2018

The progenitors of astronomical transients are linked to a specific stellar population and galactic environment, and observing their host galaxies hence constrains the physical nature of the transient itself. Here, we use imaging from the Hubble Space Telescope, and spatially resolved, medium-resolution spectroscopy from the Very Large Telescope obtained with X-shooter and MUSE to study the host of the very luminous transient ASASSN-15lh. The dominant stellar population at the transient site is old (around 1 to 2 Gyr) without signs of recent star formation. We also detect emission from ionized gas, originating from three different, time invariable, narrow components of collisionally excited metal and Balmer lines. The ratios of emission lines in the Baldwin-Phillips-Terlevich diagnostic diagram indicate that the ionization source is a weak active galactic nucleus with a black hole mass of
M• = 5-3+8 × 108 M⊙, derived through the M•-σ relation. The narrow line components show spatial and velocity offsets on scales of 1 kpc and 500 km s-1, respectively; these offsets are best explained by gas kinematics in the narrow-line region. The location of the central component, which we argue is also the position of the supermassive black hole, aligns with that of the transient within an uncertainty of 170 pc. Using this positional coincidence as well as other similarities with the hosts of tidal disruption events, we strengthen the argument that the transient emission observed as ASASSN-15lh is related to the disruption of a star around a supermassive black hole, most probably spinning with a Kerr parameter a• ≳ 0.5.
A 1.3 mm SMA survey of 29 variable young stellar objects
Authors: Liu Hauyu Baobab , Dunham Michael M. , Pascucci Ilaria , Bourke Tyler L. , Hirano Naomi , Longmore Steven , Andrews Sean , Carrasco-González Carlos , Forbrich Jan , Galván-Madrid Roberto , Girart Josep M. , Green Joel D. , Juárez Carmen , Kóspál Ágnes , Manara Carlo F. , Palau Aina , Takami Michihiro , Testi Leonardo , Vorobyov Eduard I.
Published: January 2018

Context. Young stellar objects (YSOs) may undergo periods of active accretion (outbursts), during which the protostellar accretion rate is temporarily enhanced by a few orders of magnitude. Whether or not these accretion outburst YSOs possess similar dust and gas reservoirs to each other, and whether or not their dust and gas reservoirs are similar as quiescent YSOs, are issues yet to be clarified. Aims. The aim of this work is to characterize the millimeter thermal dust emission properties of a statistically significant sample of long and short duration accretion outburst YSOs (i.e., FUors and EXors) and the spectroscopically identified candidates of accretion outbursting YSOs (i.e., FUor-like objects).

Methods. We have carried out extensive Submillimeter Array (SMA) observations mostly at ~225 GHz (1.33 mm) and ~272 GHz (1.10 mm), from 2008 to 2017. We covered accretion outburst YSOs located at <1 kpc distances from the solar system.

Results. We analyze all the existing SMA data of such objects, both published and unpublished, in a coherent way to present a millimeter interferometric database of 29 objects. We obtained 21 detections at >3σ significance. Detected sources except for the two cases of V883 Ori and NGC 2071 MM3 were observed with ~1″ angular resolution. Overall our observed targets show a systematically higher millimeter luminosity distribution than those of the M* > 0.3 M⊙ Class II YSOs in the nearby (≲400 pc) low-mass star-forming molecular clouds (e.g., Taurus, Lupus, Upp Scorpio, and Chameleon I). In addition, at 1 mm our observed confirmed binaries or triple-system sources are systematically fainter than the rest of the sources even though their 1 mm fluxes are broadly distributed. We may have detected ~30−60% millimeter flux variability from V2494 Cyg and V2495 Cyg, from the observations separated by approximately one year.
A Highly Efficient CuCl2-Catalyzed C–S Coupling of Aryl Iodides with Tetraalkylthiuram Disulfides: Synthesis of Aryl Dithiocarbamates
Authors: Dong Zhi-Bing , Cao Qiang , Peng Han-Ying , Cheng Yu
Published: January 2018

A highly efficient copper(II)-catalyzed C–S cross-coupling reaction of aryl iodides with tetraalkylthiuram disulfides was developed. With only 1 mol% of CuCl2 as catalyst, zinc powder as reductant, and K2CO3 as base, aryl iodides reacted with tetraalkylthiuram disulfides in DMSO furnishing the corresponding aryl dithiocarbamates in good to excellent yields. This protocol is an improvement of previous work, it features convenient performance, low addition of catalyst, no requirement for any ligand, and provides good yields. The method has a broad substrate scope and uses cheap and readily available starting materials.