bluuebunny/crossref_metadata_2025 huggingface dataset:
Control and optimisation of hybrid electric propulsion system for light aircraft
Authors: Savvaris Al , Xie Ye , Wang Letian , Wang Siqi , Tsourdos Antonios
Published: February 2018

The growing economical and environmental pressures have accelerated the research and development of hybrid electric power technology in order to increase aircraft performance and reduce the operating and maintenance costs. There has been a big increase in the electrical power rating on new aircraft entering into service. This study gives an overview of the design and development of a hybrid electric propulsion system for light General Aviation aircraft. The theoretical and practical challenges are reviewed and elaborated firstly. The system architecture design is based on a parallel configuration. The ground test of the developed hardware‐in‐the‐loop system is presented based on a test flight mission.
CMV reduction for five‐level ANPC converter by PS‐PWM strategy
Authors: Liu Feipeng , Xu Lie , Wang Kui , Zhou Peiyi , Li Yongdong
Published: February 2018

Five‐level active neutral point clamped (ANPC) converter has become one of the most attractive topologies in industry applications, especially in the field of the motor drive. A novel common‐mode voltage (CMV) reduction strategy for five‐level ANPC is presented, which is based on the phase‐shifted pulse‐width modulation (PS‐PWM). A basic PS‐PWM method is presented, which can realise the NP voltage and the flying capacitor (FC) voltages balance. Moreover, a general CMV reduction method is summarised. The proposed CMV reduction strategy can minimise the CMV by injecting zero‐sequence voltage to the modulation wave and it does not affect the ability of NP voltage and FC voltages balance. The validity of the proposed CMV reduction method based on PS‐PWM strategy is verified by simulation.
State‐of‐the‐art and some considerations on thermal load analysis and thermal management for hydraulic system in MEA
Authors: Li Dong , Dong Sujun , Wang Jun , Li Yunhua
Published: February 2018

Hydraulic system is an important part in aircraft secondary energy‐resource system, its pumping source contains engine‐driven pump (EDP) and electrical‐motor‐driven pump, and it is in charge of safe and reliable power transmission for flight control actuation in the aircraft. The power losses in hydraulic system will inevitably result in the temperature rise of hydraulic system, and which will seriously affect the performances of hydraulic system. Therefore, to cool thermal load and control hydraulic oil temperature in allowable range is necessary. This survey paper reviews the present status of thermal load analysis and thermal management of the aircraft hydraulic system, especially more electric aircraft (MEA), and proposes fuel/hydraulic oil heat exchanger is the more effective heat dissipation component for fuel oil as heat sink be directly burned in burner without the extra cooling cost. Moreover, this paper provides some considerations and thorough analysis on thermal management schemes and actuators in power by wire transmission system of MEA. The main summarised conclusions and proposed considerations have the important practical significances to design and high efficient operation of airborne hydraulic system.
Finite state machine control for aircraft electrical distribution system
Authors: Spagnolo Cosimo , Sumsurooah Sharmila , Hill Christopher Ian , Bozhko Serhiy
Published: February 2018

This study deals with the development of new control logic for more electric aircraft (MEA) electrical power systems (EPSs). A key aspect of the MEA concept is that traditional pneumatic and hydraulic loads are replaced by electrical equivalents. These new electrical systems are more reliable, highly efficient, and easier to replace or maintain. However, as the number of on‐board electrical loads increases the electrical distribution systems on‐board are becoming more and more complex. As a result, the control system needs to be adapted and improved in order to allow better manage the overall electrical energy flow, provide faster computational operations, and ensure operation of safety‐critical loads under all fault scenarios. This study first gives a brief analysis of the different electrical system topologies before outlining potential control strategies which may be applicable to future MEA EPSs. A new control concept for MEA EPSs is then investigated and considered as a potential substitute of the classical control systems. Finally, a model of the newly proposed logic is implemented and simulated showing how it is able to select and apply a correct reconfiguration of the electrical system under different operating conditions.
Transient simulation and analysis of wing electrothermal ice protection system
Authors: Peng Li , Yuanli Kang , Yupeng Song , Xunan He
Published: February 2018

The transient behaviour of electric heating and de‐icing of the wing is studied by numerical method. The thermal convection coupling method based on the equivalent heat transfer coefficient and the boundary condition iteration is developed for the two designed schemes of the electric heating system. According to the surface temperature, the internal temperature, and the icing condition, the system transient performance is investigated. The purpose of this study is to establish the de‐icing transient model of the wing ice protection system, simulate the transient de‐icing process and form the method of performance estimation. The results under different working conditions show that the temperature distribution of the skin surface is not uniform, rather presents certain regularity. The rising rate of temperature decreases with the increase of the temperature. The trend is more obvious at lower ambient temperature, when the ambient temperature rises, the surface temperature rises rapidly in a short period. Scheme 2 has certain advantages in heating capability, while the hot knives structure of scheme 1 can narrow and split the icing area.
Behavioural modelling and power quality simulation of a HVDC electric power system for MEA
Authors: Yue Wang , Yannian Hui , Yuanli Kang
Published: February 2018

High‐voltage direct current (HVDC) electric power system (EPS) is a promising architecture for more electric aircraft (MEA). With more electric power used, a higher voltage is necessary to make aircrafts more efficient and less weighted. However, there are no standards can be followed to evaluate the power quality of HVDC EPS, especially for 540 VDC system. In this study, a potential HVDC EPS is proposed and power quality is studied by simulation. Behavioural models of the system are established in detail from source to load. Three kinds of typical loads of MEA are defined and their impacts on power quality are analysed including resistances, power electronic converters, and motors. Some suggestions are provided for design and integration of the EPS for MEA.
Pole ratio and operation mode influence on the excitation system of three‐stage synchronous starter/generator
Authors: Sun Chenghao , Liu Weiguo , Zhang Zan , Jiao Ningfei , Pang Ji , Li Dan
Published: February 2018

For the three‐stage synchronous starter/generator, the pole ratio studied here is defined as the pole number of the main generator (MG) to that of the main exciter (ME) ratio and the operation mode means the operation mode of the rectifier at rated load in the generating mode. In this study, the pole ratio and the operation mode influence on the excitation system (consisting of the ME and the rotating rectifier) when the MG is short‐circuited has been analysed. Simulation results show that, instead of pole ratio, the operation mode of the rectifier has much more to do with minimising current shock to the excitation system when the MG is short‐circuited in the generation mode. Further, it's better to design the ME and MG to make the rectifier operate at mode 2 or 3 to reduce current shock.
Methods for building ATRU real‐time model based on different application scenarios
Authors: Sun Haocheng , Kang Yuanli , Hui Yannian , Wang Yue
Published: February 2018

This study introduces three methods for building an auto‐transformer rectifier units (ATRU) real‐time model based on different application scenarios. Real‐time models run on an advanced real‐time simulator that has the capability to leverage central processing units and field programming gate arrays. In the first section, the disadvantages of the off‐line simulation are explained and the solution is offered through real‐time simulation. In the second section, applications of real‐time simulation in a more electric aircraft (MEA) electric power system will be presented. In the third section, methods to build the ATRU real‐time model are illustrated based on requirements and different scenarios. Simulations are conducted to demonstrate the agreement between the results and analysis.
Model‐based design of a starting control system with an LC filter for an aircraft start generator
Authors: Li Hejie , Chen Zhihui , Li Jincai , Zhang Zhuoran
Published: February 2018

This study presents the design and implementation of a starting control system with an LC filter for an aircraft start generator (SG). Based on the optimal design of the filter, a small‐signal model is built to account for improved stable and dynamic performance. The transfer function is deduced to tune the control parameters of the whole system. The design of the controller aims at a 75 kVA SG drive system and is verified in a digital signal processor. Finally, simulation results are obtained to predict the behaviour of the starting control system during a transient duty and experimental results show characteristics of the starting process.
Etched Al0.32Ga0.68 N/GaN HEMTs with high output current and breakdown voltage (>600 V)
Authors: Duan Baoxing , Xie Shenlong , Guo Haijun , Yang Yintang
Published: February 2018

By etching the AlGaN layer close to the gate edge of the drain side, the novel AlGaN/GaN high‐electron‐mobility transistor with the etched AlGaN epitaxial layer (etched AlGaN/GaN high‐electron‐mobility transistors, HEMTs) is proposed in this work with the high‐resistance GaN buffer layer. The relationship between the 2D electron gas (2DEG) concentration and the thickness of the AlGaN layer has been explored. The 2DEG density under the etched barrier is reduced to optimise the surface electric field and mobility of 2DEG. The electric field is reshaped by the etched AlGaN layer, featuring an extra electric field peak far away from the gate edge. The electric field peak near the gate is decreased effectively because of the extra electric field peak, which therefore improves the breakdown voltage (BV). The mobility of 2DEG is increased because of the low 2DEG concentration, which improves the output current (IDS). The experimental BV is improved from 152 V for the conventional structure to 620 V for etched AlGaN/GaN HEMTs because of the optimised surface electric field. The maximum output current (Imax) is increased from 381 to 478 mA/mm. The trade‐off between the BV and Ron,sp has been improved to break the silicon limit. It is concluded that the gate‐edge etching technique can significantly increase both BV and IDS for AlGaN/GaN HEMTs.
High sensitivity vanadium–vanadium pentoxide–aluminium metal–insulator–metal diode
Authors: Abdel‐Rahman Mohamed , Issa Khaled , Zia Muhammad F. , Alduraibi Mohammad , Siraj Mohammad , Ragheb Amr , Alshebeili Saleh
Published: February 2018

This work reports on the fabrication of an improved sensitivity metal–insulator–metal (MIM) diode. They devise an asymmetric structure diode that cascades vanadium, vanadium pentoxide, and aluminium (V–V2O5–Al) thin film layers. The MIM diode is fabricated using electron‐beam lithography, sputter deposition and metal liftoff techniques. X‐ray photoelectron spectroscopy analysis is performed to determine the phase composition of the V2O5 insulating thin film. Electrical characterisation of the fabricated V–V2O5–Al shows a clear high sensitivity at −316 mV that reaches −8.52 V−1 with a dynamic resistance of 5.024 kΩ.
Torsional vibration analysis of nanorods with elastic torsional restraints using non‐local elasticity theory
Authors: Yayli Mustafa Özgür
Published: February 2018

In this work, torsional vibration of nanorods with torsional elastic boundary conditions is presented via non‐local elasticity theory. The present model developed based on non‐local elasticity theory gives the opportunity to interpret size effect. Two torsional elastic springs are attached to a nanorod at both ends. A mathematical transformation known as ‘Stoke transformation’ is utilised to work out the Fourier series for the nanorods with torsional restraints. A coefficient matrix including torsional coefficients is determined by using non‐local boundary conditions. A comparison is performed to validate numerical simulations with those given in the literature and the results agree with each other exactly. The non‐local effects of torsional end restraints on the free torsional vibration response are investigated for both deformable and rigid boundary conditions.
Approach to suppress ambipolarity and improve RF and linearity performances on ED‐Tunnel FET
Authors: Chandan Bandi Venkata , Dasari Sushmitha , Yadav Shivendra , Sharma Dheeraj
Published: February 2018

This work reports a dual metal bipolar gate‐based electrically doped tunnel field‐effect transistor (DMBG‐ED‐TFET) which overcomes the ambipolarity issue and gives improved radio frequency (RF) and linearity metrics. The formations of , drain and source regions in this device is performed by applying polarity biases at polarity gate (PG)‐1 and PG‐2 with 1.2 and −1.2 V. In DMBG‐ED‐TFET, the gate is alienated into three subdivisions and each subdivision named as tunnel gate (M1), BG (M2) and auxiliary gate (M3) with their respective work functions as , and , respectively. Finally, some existent applications were applied on a proposed device with different possible combinations (work function). Those different possible combinations of work function, the proposed device (DMBG‐ED‐TFET) gives superior results with , where is near to source region because to increase the current and is located near the drain region to overwhelm the ambipolarity. Additionally, the application of work function engineering on the proposed device results in improving the DC characteristics along with analogue/RF and linearity figure of merits (VIP3, IIP3 and IMD3) also discussed.
Practical Synthesis of Functionalized Chromeno[3,4-c]pyridine Derivatives via a CuCl2-Catalyzed Tandem Reaction of the Blaise Reaction Intermediates and 3-Cyanocoumarins
Authors: Li Jian-Jun , Chen Zhiwei , Fan Yangyang , Zheng Lei , Yang Zhaohai
Published: February 2018

This work discloses a novel and eﬃcient protocol for the construction of functionalized chromeno[3,4-c]pyridine derivatives from the Blaise reaction intermediates and 3-cyanocoumarins through a CuCl2-catalyzed sequential Michael addition/intramolecular cyclization/oxidative aromatization reaction. This new method shows the advantages of mild reaction conditions, easy workup, nonchromatographic puriﬁcation technique, good functional group tolerance, and moderate to good yields.
The COSTA Study: Sternal Closure in High-Risk Patients - A Prospective Randomized Multicenter Trial
Authors: Heilmann Claudia , Sorg Stefan , Mueller Matthias , Kueri Sami , Schmoor Claudia , Siepe Matthias , Beyersdorf Friedhelm , Leinberger Tetyana
Published: February 2018

Background Median sternotomy in patients with risk factors for wound healing is associated with high rates of postoperative wound infections and sternum instability.

Methods A total of 338 patients with elective first median sternotomy and at least four predefined risk factors were randomized between Sternal Talon (Gebrüder Martin GmbH & Co. KG—KLS Martin Group, Tuttlingen, Germany) and wire cerclage. The primary end point was mediastinitis and/or sternal instability within 30 ± 5 days, and the secondary end points were mediastinitis and/or sternal instability within 60 ± 5 days; incidence of pneumonia during hospitalization within the first 30 (±5) days and chest pain intensity.

Results The primary end point was reached in 10 Sternal Talon and 7 wire cerclage patients (6.2 vs. 4.7%, odds ratio [OR]: 1.3, 95% confidence interval [CI]: 0.5–3.6, p = 0.57) from 338 randomized patients. Sternal Talon group, n = 170 patients versus wire cerclage group, n = 168 patients. The differences between treatment groups with regard to the incidence of mediastinitis/sternum instability within the first 60 (±5) days after the primary sternum closure and the incidence of pneumonia during the hospitalization within the first 30 (±5) days were not statistically significant, either. We observed comparable rates of superficial surgical site infection (SSI) in Sternal Talon and wire cerclage patients (16.1 vs. 12.1%, OR: 1.4, 95% CI: 0.7–2.7, p = 0.31).

Conclusion According to these data, there is no statistically significant difference between Sternal Talon closure and wire cerclage in reducing the incidence of mediastinitis and superficial SSI after primary closure of median sternotomy in high-risk patients.
Stable Rat Model of Mechanical Allodynia in Diabetic Peripheral Neuropathy: The Role of Nerve Compression
Authors: Liao Chenlong , Yang Min , Liu Pengfei , Zhong Wenxiang , Zhang Wenchuan
Published: February 2018

Background Preclinical studies involving animal models are essential for understanding the underlying mechanisms of diabetic neuropathic pain.

Methods Rats were divided into four groups: two controls and two experimental. Diabetes mellitus was induced by streptozotocin (STZ) injection in two experimental groups. The first group involved one sham operation. The second group involved one latex tube encircling the sciatic nerve. The vehicle-injection rats were used as two corresponding control groups: sham operation and encircled nerves. By the third week, STZ-injected rats with encircled nerves were further divided into three subgroups: one involving continuing observation and the other two involving decompression (removal of the latex tube) at different time points (third week and fifth week). Weight and blood glucose were monitored, and behavioral analysis, including paw withdrawal threshold (PWT) and latency, was performed every week during the experimental period (7 weeks).

Results Hyperglycemia was induced in all STZ-injected rats. A significant increase in weight was observed in the control groups when compared with the experimental groups. By the third week, more STZ-injected rats with encircled nerves developed mechanical allodynia than those without (P < 0.05), while no significant difference was noted (P > 0.05) on the incidence of thermal hyperalgesia. Mechanical allodynia, but not thermal hyperalgesia, could be ameliorated by the removal of the latex tube at an early stage (third week).

Conclusion With the combined use of a latex tube and STZ injection, a stable rat model of painful diabetic peripheral neuropathy (DPN) manifesting both thermal hyperalgesia and mechanical allodynia has been established.
Meta-analysis of Timing for Microsurgical Free-Flap Reconstruction for Lower Limb Injury: Evaluation of the Godina Principles
Authors: Roy Mélissa , Patel Ashit , Haykal Siba
Published: February 2018

Background In 1986, Marko Godina published his seminal work regarding the timing of free-flap reconstruction for traumatic extremity defects. Early reconstruction, compared with delayed and late reconstruction resulted in significant decreases in free-flap failure rate, post-operative infections, hospitalization time, bone healing time, and number of additional anesthesias. The objective of this manuscript was to evaluate whether these principles continue to apply.

Methods A meta-analysis was performed analyzing articles from Medline, Embase, and Pubmed. Four hundred and ninety-two articles were screened, and 134 articles were assessed for eligibility. Following full-text review, 43 articles were included in this study.

Results The exact timing for free-flap reconstruction, free-flap failure rate, infection rate, and follow-up was defined in all 43 articles. Early free-flap reconstruction was found to have significantly lower rates of free-flap failure and infection in comparison to delayed reconstruction (p = 0.008; p = 0.0004). Compared with late reconstruction, early reconstruction was found to have significantly lower infection rates only (p = 0.01) with no difference in free-flap failures rates. Early reconstruction was found to lead to fewer additional procedures (p = 0.03). No statistical significance was found for bone healing time or hospitalization time.

Conclusion Early free-flap reconstruction performed within the first 72 hours resulted in a decreased rate of free-flap failures, infection, and additional procedures with no difference in other parameters. The largest majority of free flaps continue to be performed in a delayed time frame.
Use of Social Media and an Online Survey to Discuss Complex Reconstructive Surgery: A Case of Upper Lip Reconstruction with 402 Responses from International Microsurgeons
Authors: Kwon Soo-Ha , Lee Che-Hsiung , Hsu Angela , Shafarenko Mark , Omar Usama , Tzou Chieh-Han , Roka-Palkovits Julia , Beltrán P Aldo , Liakos Dimitri , Chang Tommy
Published: February 2018

Background The best reconstructive strategy for upper lip defects is still in debate. The purpose of this study was to analyze the decisions made by international microsurgeons, who were participated through online questionnaire, distributed by email and social media network.

Materials and Methods A case of a two-thirds upper lip oncologic defect was presented via an online questionnaire and 402 microsurgeons replied their treatment options. The data were then analyzed according to the geographic area, microsurgical fellowship, seniority, and subspecialty. All the data were analyzed using SPSS 22.

Results A total of 27.7% of microsurgeons chose a free flap, while 72.3% chose a local/pedicle flap as their preferred method for reconstruction. The most common choice of free and local/pedicle flaps was radial forearm (73.6%) and Abbé (36.2%), respectively. The microsurgeons in Europe preferred local/pedicle flaps than free flap when compared with Middle/South America, Asia-Pacific, Africa and South Asia/Middle East (11.6% versus 50%, 43.4%, 29.3% and 27.3%, respectively, multivariant p < 0.05). The microsurgeons with microsurgical fellowships preferred to use free flaps (32.9% versus 17.5%, multivariant p = 0.021). There was no difference for the seniority and specialty of the microsurgeons.

Conclusions The online questionnaire is valuable and feasible for obtaining experts' opinions. This study provides a current global overview of surgical preferences for this common complicated clinical scenario.
Thoracic Endovascular Repair for Acute Traumatic Transection of the Descending Thoracic Aorta and Postendovascular Remodeling Change
Authors: Kim Young , Yoon Yong , Shin Helen , Park Keun , Baek Wan , Kim Joung
Published: February 2018

Background The recently developed thoracic endovascular repair (TEVAR) technique seems to offer a good alternative for treating acute traumatic transection of the thoracic aorta (TTA). We reviewed our experience of TEVAR in cases of acute traumatic transection and analyzed the subsequent remodeling changes.

Methods The medical records of 17 patients who underwent TEVAR for TTA were reviewed. The trauma mechanisms, anatomical characteristics of the transected aortas, technical details of TEVAR, and postprocedural results were reviewed.

Results The overall mean injury severity score was 53 ± 12. On three-dimensional computed tomography (CT), the mean distance of transection from the left subclavian artery was 14 ± 9 (0–31) mm. Fifteen patients presented an aortic pseudoaneurysm and two patients had impending rupture. TEVAR was performed emergently under general endotracheal induction. Technical success was achieved and complete pseudoaneurysm sealing was confirmed with aortography in all 17 patients. Two patients (12%) died of hypovolemic shock and hyperkalemia; however, no late death or stent-related complication occurred during the 45 ± 32 (6–102) months of follow-up. During a mean CT follow-up of 35 months, the mean aortic diameter increased by 2 (0–5) mm and pseudoaneurysm lesions completely disappeared in all patients.

Conclusions TEVAR resulted in good early survival in patients with TTA. No late or stent graft-related event was encountered up to a maximum of 9 years after surgery. We recommend that patients with grade III or higher TTA should undergo emergency surgery. Moreover, we consider that long-term follow-up and blood pressure management are essential when the proximal aortic diameter is found to increase slightly after TEVAR on follow-up CT.
Impact of type 2 Diabetes and Metformin use on Vitamin B12 Associated Biomarkers - an Observational Study
Authors: Metaxas Corina , Zurwerra Chantal , Rudofsky Gottfried , Hersberger Kurt , Walter Philipp
Published: February 2018

Aims Assessment of the impact of type 2 diabetes (T2DM) and metformin use on vitamin B12 (VB12) associated biomarkers and their suitability to represent VB12 supply.

Methods Differences of VB12, holotranscobalamine (HoloTc), the biologically active fraction  (%AB12)=HoloTc/VB12*100 and homocystein (Hcy) were analysed i) among diabetic outpatients with (DMMet+ ) and without metformin use (DMMet-) and ii) in comparison to an external non-diabetic reference group with low VB12 (<200 pmol/L).

Results VB12 associated biomarkers were distributed equally between DMMet+  (n=29, 58%) and DMMet- (n=21, 42%). Significant differences in %AB12 in diabetic patients with low VB12 (n=19) compared to the non-diabetic reference group (n=31) were found. Higher %AB12 was associated with diabetes. Hcy levels were significantly associated with age, folic acid level, renal function and HoloTc but not with VB12.

Conclusions In T2DM patients with low VB12, %AB12 was confirmed as being higher in comparison to nondiabetic patients. The effect was not clearly attributable to metformin use. HoloTc was unaffected by the lowering of VB12 and significantly associated with the functional marker Hcy. Both findings support the use of HoloTc for the assessment of VB12 supply in diabetic patients.
Search for Pharmacoepigenetic Correlations in Type 2 Diabetes Under Sulfonylurea Treatment
Authors: Karaglani Makrina , Ragia Georgia , Panagopoulou Maria , Balgkouranidou Ioanna , Nena Evangelia , Kolios George , Papanas Nikolaos , Manolopoulos Vangelis , Chatzaki Ekaterini
Published: February 2018

Sulfonylureas are insulin secretagogues which act in pancreatic β cells by blocking the KATP channels encoded by KCNJ11 and ABCC8 genes. In the present study, a pharmacoepigenetic approach was applied for the first time, investigating the correlation of KCNJ11 and ABCC8 gene promoter methylation with sulfonylureas-induced mild hypoglycemic events as well as the KCNJ11 E23K genotype. Sodium bisulfite-treated genomic DNA of 171 sulfonylureas treated T2DM patients previously genotyped for KCNJ11 E23K, including 88 that had experienced drug-associated hypoglycemia and 83 that had never experienced hypoglycemia, were analyzed for DNA methylation of KCNJ11 and ABCC8 gene promoters via quantitative Methylation-Specific PCR. KCNJ11 methylation was detected in 19/88 (21.6%) of hypoglycemic and in 23/83 (27.7%) of non-hypoglycemic patients (p=0.353), while ABCC8 methylation in 6/83 (7.2%) of non-hypoglycemic and none (0/88) of the hypoglycemic patients (p=0.012). Methylation in at least one promoter (KCNJ11 or ABCC8) was significantly associated with non-hypoglycemic patients who are carriers of KCNJ11 EK allele (p=0.030). Our data suggest that ABCC8 but not KCNJ11 methylation is associated to hypoglycemic events in sulfonylureas-treated T2DM patients. Furthermore, it is demonstrated that the KCNJ11 E23K polymorphism in association to either of the two genes’ DNA methylation may have protective role against sulfonylurea-induced hypoglycemia.
Elevated Levels of Estrogen Suppress Hepcidin Synthesis and Enhance Serum Iron Availability in Premenopausal Women
Authors: Bajbouj Khuloud , Shafarin Jasmin , Allam Hilda , Madkour Mohamed , Awadallah Samir , El-Serafy Ahmed , Sandeep Divyasree , Hamad Mawieh
Published: February 2018

Clinical and experimental observations have long suggested that elevated levels of estrogen associate with increased serum iron availability. Additionally, recent work has shown that estrogen can downregulate hepcidin synthesis in vitro. This study aims at assessing whether the ability of estrogen to downregulate hepcidin synthesis translates into changes in serum iron status. Hepcidin synthesis was evaluated in MCF-7, Hep-G2 and SKOV-3 cells treated with increasing concentrations of estrogen and cultured for up to 24 h post treatment. The correlation between levels of serum estrogen, hepcidin and iron was assessed using serum samples collected from 153 premenopausal women at random and samples collected from 6 women at days 1, 5, 10, 16, 21 and 28 of the monthly cycle. Estrogen-treated MCF-7 cells showed a significant reduction in hepcidin synthesis, especially at 20 nM/24 h E2 treatment. Hepcidin synthesis was also significantly reduced in Hep-G2 and SKOV-3 cells at 20 nM/24 h E2 treatment. In serum samples collected at random, estrogen (P=0.022; R=−0.213) and iron (P=0.028; R=−0.316) correlated negatively with hepcidin and positively with each other (P=0.033; R=0.319). An overall similar pattern was also observed in monthly cycle-timed samples. These findings suggest that elevated levels of estrogen reduce hepcidin synthesis as means of enhancing serum iron content in menstruating women.
High-intensity Interval Training Frequency: Cardiometabolic Effects and Quality of Life
Authors: Stavrinou Pinelopi , Bogdanis Gregory , Giannaki Christoforos , Terzis Gerasimos , Hadjicharalambous Marios
Published: February 2018

The effects of high intensity interval training (HIIT) frequency on cardiometabolic health and quality of life were examined in 35 healthy inactive adults (age: 31.7±2.6 yrs, VO2peak: 32.7±7.4 ml·kg−1
·min−1). Participants were randomly assigned to a control (CON) and two training groups, which performed 10×60-s cycling at ~83% of peak power, two (HIIT-2) or three times per week (HIIT-3) for eight weeks. Compared with CON, both training regimes resulted in similar improvements in VO2peak (HIIT-2: 10.8%, p=0.048, HIIT-3: 13.6%, p=0.017), waist circumference (HIIT-2: -1.4 cm, p=0.048, HIIT-3: -2.4 cm, p=0.028), thigh cross-sectional area (HIIT-2: 11.4 cm2, p=0.001, HIIT-3: 9.3 cm2, p=0.001) and the physical health component of quality of life (HIIT-2: 8.4, p=0.001, HIIT-3: 12.2, p=0.001). However, HIIT-3 conferred additional health-related benefits by reducing total body and trunk fat percentage (p<0.05, compared with CON), total cholesterol and low-density lipoprotein-cholesterol (p<0.02, compared with CON) and by improving the mental component of quality of life (p=0.045, compared with CON). In conclusion, performing HIIT only twice per week is effective in promoting cardiometabolic health-related adaptations and quality of life in inactive adults. However, higher HIIT frequency is required for an effect on fat deposits, cholesterol and mental component of well-being.
scEpath: energy landscape-based inference of transition probabilities and cellular trajectories from single-cell transcriptomic data
Authors: Jin Suoqin , MacLean Adam L , Peng Tao , Nie Qing
Published: February 2018

Motivation

Single-cell RNA-sequencing (scRNA-seq) offers unprecedented resolution for studying cellular decision-making processes. Robust inference of cell state transition paths and probabilities is an important yet challenging step in the analysis of these data.

Results

Here we present scEpath, an algorithm that calculates energy landscapes and probabilistic directed graphs in order to reconstruct developmental trajectories. We quantify the energy landscape using ‘single-cell energy’ and distance-based measures, and find that the combination of these enables robust inference of the transition probabilities and lineage relationships between cell states. We also identify marker genes and gene expression patterns associated with cell state transitions. Our approach produces pseudotemporal orderings that are—in combination—more robust and accurate than current methods, and offers higher resolution dynamics of the cell state transitions, leading to new insight into key transition events during differentiation and development. Moreover, scEpath is robust to variation in the size of the input gene set, and is broadly unsupervised, requiring few parameters to be set by the user. Applications of scEpath led to the identification of a cell-cell communication network implicated in early human embryo development, and novel transcription factors important for myoblast differentiation. scEpath allows us to identify common and specific temporal dynamics and transcriptional factor programs along branched lineages, as well as the transition probabilities that control cell fates.

Availability and implementation

A MATLAB package of scEpath is available at https://github.com/sqjin/scEpath.

Supplementary information

Supplementary data are available at Bioinformatics online.
Optimal extraction methods for the simultaneous analysis of DNA from diverse organisms and sample types
Authors: Hermans Syrie M. , Buckley Hannah L. , Lear Gavin
Published: February 2018

Using environmental DNA (eDNA) to assess the distribution of micro‐ and macroorganisms is becoming increasingly popular. However, the comparability and reliability of these studies is not well understood as we lack evidence on how different DNA extraction methods affect the detection of different organisms, and how this varies among sample types. Our aim was to quantify biases associated with six DNA extraction methods and identify one which is optimal for eDNA research targeting multiple organisms and sample types. We assessed each methods’ ability to simultaneously extract bacterial, fungal, plant, animal and fish DNA from soil, leaf litter, stream water, stream sediment, stream biofilm and kick‐net samples, as well as from mock communities. Method choice affected alpha‐diversity for several combinations of taxon and sample type, with the majority of the differences occurring in the bacterial communities. While a single method performed optimally for the extraction of DNA from bacterial, fungal and plant mock communities, different methods performed best for invertebrate and fish mock communities. The consistency of methods, as measured by the similarity of community compositions resulting from replicate extractions, varied and was lowest for the animal communities. Collectively, these data provide the first comprehensive assessment of the biases associated with DNA extraction for both different sample types and taxa types, allowing us to identify DNeasy PowerSoil as a universal DNA extraction method. The adoption of standardized approaches for eDNA extraction will ensure that results can be more reliably compared, and biases quantified, thereby advancing eDNA as an ecological research tool.
Resolving allele dosage in duplicated loci using genotyping‐by‐sequencing data: A path forward for population genetic analysis
Authors: McKinney Garrett J. , Waples Ryan K. , Pascal Carita E. , Seeb Lisa W. , Seeb James E.
Published: February 2018

Whole‐genome duplications have occurred in the recent ancestors of many plants, fish and amphibians. Signals of these whole‐genome duplications still exist in the form of paralogous loci. Recent advances have allowed reliable identification of paralogs in genotyping‐by‐sequencing (GBS) data such as that generated from restriction‐site‐associated DNA sequencing (RADSeq); however, excluding paralogs from analyses is still routine due to difficulties in genotyping. This exclusion of paralogs may filter a large fraction of loci, including loci that may be adaptively important or informative for population genetic analyses. We present a maximum‐likelihood method for inferring allele dosage in paralogs and assess its accuracy using simulated GBS, empirical RADSeq and amplicon sequencing data from Chinook salmon. We accurately infer allele dosage for some paralogs from a RADSeq data set and show how accuracy is dependent upon both read depth and allele frequency. The amplicon sequencing data set, using RADSeq‐derived markers, achieved sufficient depth to infer allele dosage for all paralogs. This study demonstrates that RADSeq locus discovery combined with amplicon sequencing of targeted loci is an effective method for incorporating paralogs into population genetic analyses.
Impacts of licensed premises trading hour policies on alcohol‐related harms
Authors: Atkinson Jo‐An , Prodan Ante , Livingston Michael , Knowles Dylan , O'Donnell Eloise , Room Robin , Indig Devon , Page Andrew , McDonnell Geoff , Wiggers John
Published: February 2018

Background and aim

Evaluations of alcohol policy changes demonstrate that restriction of trading hours of both ‘on’‐ and ‘off’‐licence venues can be an effective means of reducing rates of alcohol‐related harm. Despite this, the effects of different trading hour policy options over time, accounting for different contexts and demographic characteristics, and the common co‐occurrence of other harm reduction strategies in trading hour policy initiatives, are difficult to estimate. The aim of this study was to use dynamic simulation modelling to compare estimated impacts over time of a range of trading hour policy options on various indicators of acute alcohol‐related harm.

Methods

An agent‐based model of alcohol consumption in New South Wales, Australia was developed using existing research evidence, analysis of available data and a structured approach to incorporating expert opinion. Five policy scenarios were simulated, including restrictions to trading hours of on‐licence venues and extensions to trading hours of bottle shops. The impact of the scenarios on four measures of alcohol‐related harm were considered: total acute harms, alcohol‐related violence, emergency department (ED) presentations and hospitalizations.

Results

Simulation of a 3 a.m. (rather than 5 a.m.) closing time resulted in an estimated 12.3 ± 2.4% reduction in total acute alcohol‐related harms, a 7.9 ± 0.8% reduction in violence, an 11.9 ± 2.1% reduction in ED presentations and a 9.5 ± 1.8% reduction in hospitalizations. Further reductions were achieved simulating a 1 a.m. closing time, including a 17.5 ± 1.1% reduction in alcohol‐related violence. Simulated extensions to bottle shop trading hours resulted in increases in rates of all four measures of harm, although most of the effects came from increasing operating hours from 10 p.m. to 11 p.m.

Conclusions

An agent‐based simulation model suggests that restricting trading hours of licensed venues reduces rates of alcohol‐related harm and extending trading hours of bottle shops increases rates of alcohol‐related harm. The model can estimate the effects of a range of policy options.
Exploring wildlife predation in the Limpopo Province of South Africa: A double‐hurdle approach
Authors: Schepers Anché , Matthews Nicolette , van Niekerk Hermias Nieuwoudt
Published: February 2018

Predation is a well‐known problem in South Africa with large losses in the small and large livestock sectors. Predation in the wildlife ranching industry has also become more of a concern, as the financial losses due to predation on valuable antelope species are large. Predation data for small, large, and scarce/colour‐variant antelope species were collected using a structured questionnaire from wildlife ranchers in the Limpopo province, South Africa. We explore the factors that influence predation on these species by determining whether the perceptions of predation and consequent managerial decisions affect predation. The use of nonlethal control methods can be successfully employed to reduce the probability of predation occurrences, however, a combination of lethal and nonlethal control methods were used to reduce the level of predation. The type of antelope species will determine the type of predation control method to be employed. Therefore, the antelope species should be taken into account when making predation management decisions.
A camera trap assessment of the forest mammal community within the transitional savannah‐forest mosaic of the Batéké Plateau National Park, Gabon
Authors: Hedwig Daniela , Kienast Ivonne , Bonnet Matthieu , Curran Bryan K. , Courage Amos , Boesch Christophe , Kühl Hjalmar S. , King Tony
Published: February 2018

Monitoring populations in areas of ecological transition is crucial to understanding species distributions, but also a critical conservation tool. We used camera trapping to investigate the forest mammal community in the Batéké Plateau National Park (BPNP) in Gabon, a transitional landscape that experiences severe poaching. We compiled a species inventory, investigated group sizes and activity patterns of observed species, and conducted an initial test to evaluate whether ecological gradients within this landscape influence species occurrence. Based on 6612 images and videos recorded at 40 locations during 5,902 camera days, we identified 31 mammal species, including eight classified as threatened according to the IUCN. We detected lion (Panthera leo, Linnaeus), which was thought to be extinct in Gabon, and mandrill (Mandrillus sphinx, Linnaeus), for which BPNP was thought to be outside of their natural range. Our findings suggest that BPNP supports a low species richness compared to more forested protected areas. We found no changes in species composition of the forest mammal community with increasing distance from the continuous Gabonese rainforest, but a potential decrease in abundance for some species. Continued survey efforts need to be combined with detailed ecological data collection and effective law enforcement in the region.
An intriguing, new planarian species from Tasmania, with a discussion on protandry in triclad flatworms (Platyhelminthes, Tricladida)
Authors: Sluys Ronald , Vila‐Farré Miquel , Rink Jochen , Rasko John E. J.
Published: February 2018

An account is given of an unusual new species of freshwater planarian from the Hartz Mountains in Tasmania, Australia, Romankenkius flaccidus Sluys, sp. nov. The species is characterized, among other features, by an asymmetrical penis papilla, an extremely large, elongated copulatory bursa, and by the absence of testes in animals with fully developed male and female copulatory apparatus. Instigated by the sexual cycle of this new species, the study opportunely reviews whether planarian flatworms generally are simultaneous or sequential—in particular protandrous—hermaphrodites. It is concluded that real protandry does not occur in triclads and that even less extreme cases of sexual segregation, such as complete reduction of the testes or the more or less complete separation of male and female functionality as present in some species, have only sparsely and convergently evolved within the group of the triclad flatworms.
Placental structures and their association with matrotrophy and superfetation in poeciliid fishes
Authors: Olivera‐Tlahuel Claudia , Moreno‐Mendoza Norma A. , Villagrán‐Santa Cruz Maricela , Zúñiga‐Vega J. Jaime
Published: February 2018

Both matrotrophy, the maternal provisioning of nutrients to developing embryos after fertilization, and superfetation, the simultaneous presence of two or more groups of embryos at different stages of development, occur at varying degrees among species of the fish family Poeciliidae. However, it is still unclear if these two reproductive modes depend on the presence of relatively complex placentas. We describe the ultrastructure of the maternal follicular placenta of 11 poeciliid fishes using electron microscopy. In addition, we quantified six ultrastructure characteristics that reflect the degree of complexity (number of vesicles, area of vesicles, number of microvilli, microvilli length, thickness of the maternal follicle and follicular area). Using phylogenetic comparative methods, we evaluated the relationship between degree of matrotrophy and placental characteristics. We also analysed the potential effect of the presence of superfetation on placental complexity. We found a positive relationship between the degree of matrotrophy and follicular area, number of microvilli and number and area of vesicles. Similarly, follicular area and number of microvilli were larger in species with superfetation than in those without superfetation. We conclude that high degrees of matrotrophy and superfetation are associated with placental characteristics that increase the efficiency of nutrient transfer between mother and embryos.
Functional interplay between liver X receptor and AMP‐activated protein kinase α inhibits atherosclerosis in apolipoprotein E‐deficient mice − a new anti‐atherogenic strategy
Authors: Ma Chuanrui , Zhang Wenwen , Yang Xiaoxiao , Liu Ying , Liu Lipei , Feng Ke , Zhang Xiaomeng , Yang Shu , Sun Lei , Yu Miao , Yang Jie , Li Xiaoju , Hu Wenquan , Miao Robert Q , Zhu Yan , Li Luyuan , Han Jihong , Chen Yuanli , Duan Yajun
Published: February 2018

Background and Purpose

The liver X receptor (LXR) agonist T317 reduces atherosclerosis but induces fatty liver. Metformin activates energy metabolism by activating AMPKα. In this study, we determined if interactions between metformin and T317 could inhibit atherosclerosis without activation of hepatic lipogenesis.

Experimental Approach

Apolipoprotein E‐deficient mice were treated with T317, metformin or both agents, in a high‐fat diet for 16 weeks. Then, samples of aorta, liver, macrophage and serum were collected to determine atherosclerotic lesions, fatty liver, lipid profiles and expression of related proteins. Techniques used included immunohistochemistry, histology, qRT‐PCR and Western blot.

Key Results

T317 inhibited en face and aortic root sinus lesions, and the inhibition was further enhanced by addition of metformin. Co‐treatment with metformin and T317 increased lesion stability, by increasing collagen content, and reducing necrotic cores and calcification. Formation of macrophages/foam cells and their accumulation in arterial wall were inhibited by the co‐treatment, which was accompanied by increased ABCA1/ABCG1 expression, reduced monocyte adhesion and apparent local proliferation of macrophages. Metformin blocked T317‐induced fatty liver by inhibiting T317‐induced hepatic LXRα nuclear translocation and expression of lipogenic genes and by activating AMPKα. Moreover, co‐treatment with T317 and metformin improved triglyceride metabolism by inducing expression of adipose triglyceride lipase, hormone‐sensitive lipase, PPARα and carnitine acetyltransferase and by inhibiting acyl‐CoA:diacylglycerol acyltransferase 1 expression.

Conclusions and Implications

Co‐treatment with T317 and metformin inhibited the development of atherosclerosis without activation of lipogenesis, suggesting that combined treatment with T317 and metformin may be a novel approach to inhibition of atherosclerosis.