bluuebunny/crossref_metadata_2025 huggingface dataset:
Endoplasmic reticulum chaperone BiP/GRP78 knockdown leads to autophagy and cell death of arginine vasopressin neurons in mice
Authors: Kawaguchi Yohei , Hagiwara Daisuke , Miyata Takashi , Hodai Yuichi , Kurimoto Junki , Takagi Hiroshi , Suga Hidetaka , Kobayashi Tomoko , Sugiyama Mariko , Onoue Takeshi , Ito Yoshihiro , Iwama Shintaro , Banno Ryoichi , Grinevich Valery , Arima Hiroshi
Published: November 2020

The immunoglobulin heavy chain binding protein (BiP), also referred to as 78-kDa glucose-regulated protein (GRP78), is a pivotal endoplasmic reticulum (ER) chaperone which modulates the unfolded protein response under ER stress. Our previous studies showed that BiP is expressed in arginine vasopressin (AVP) neurons under non-stress conditions and that BiP expression is upregulated in proportion to the increased AVP expression under dehydration. To clarify the role of BiP in AVP neurons, we used a viral approach in combination with shRNA interference for BiP knockdown in mouse AVP neurons. Injection of a recombinant adeno-associated virus equipped with a mouse AVP promoter and BiP shRNA cassette provided specific BiP knockdown in AVP neurons of the supraoptic (SON) and paraventricular nuclei (PVN) in mice. AVP neuron-specific BiP knockdown led to ER stress and AVP neuronal loss in the SON and PVN, resulting in increased urine volume due to lack of AVP secretion. Immunoelectron microscopy of AVP neurons revealed that autophagy was activated through the process of AVP neuronal loss, whereas no obvious features characteristic of apoptosis were observed. Pharmacological inhibition of autophagy by chloroquine exacerbated the AVP neuronal loss due to BiP knockdown, indicating a protective role of autophagy in AVP neurons under ER stress. In summary, our results demonstrate that BiP is essential for the AVP neuron system.
Relationship between depression and dorsolateral prefronto-thalamic tract injury in patients with mild traumatic brain injury
Authors: Jang Sung Ho , Kwon Hyeok Gyu
Published: November 2020

The prefrontal lobe has been considered to be closely related to depression. This study examined the relationship between depression and three prefronto-thalamic tract (PF-TT) regions (the dorsolateral prefronto-thalamic tract [DLPF-TT], ventrolateral prefronto-thalamic tract [VLPF-TT], and the orbitofronto-thalamic tract [OF-TT]) in patients with mild traumatic brain injury (TBI), using diffusion tensor tractography (DTT). Thirty-seven patients with depression following mild TBI were recruited based on Beck Depression Inventory-II (BDI-II) scores. Thirty-one normal control subjects were also recruited. The three regions of the PF-TTs were reconstructed using probabilistic tractography and DTT parameters for each of the three PF-TT regions were determined. The tract volume of the DLPF-TT and OF-TT in the patient group showed a significant decrease compared to that of the control group (p < 0.05). The BDI-II score of the patient group showed a moderate negative correlation with the tract volume value of the right (r =  − 0.33) and left (r =  − 0.41) DLPF-TT (p < 0.05). On the other hand, no significant correlations were detected between the BDI-II score of the patient group and the values of the other DTT parameters values for the three PF-TT regions (p > 0.05). Using DTT, depression was found to be closely related to a DLPF-TT injury in patients with mild TBI. We believe that evaluation of the DLPF-TT using DTT would be helpful when assessing patients with depression following mild TBI. These results can provide useful information regarding the proper application of neuromodulation in the management of depression.
Orchestration of biomimetic membrane coating and nanotherapeutics in personalized anticancer therapy
Authors: Chen Xuerui , Liu Bingbing , Tong Rongliang , Zhan Lin , Yin Xuelian , Luo Xin , Huang Yanan , Zhang Junfeng , He Wen , Wang Yanli
Published: November 2020

Benefiting from the special inherency of natural cells, diverse cell membrane-coated nanoparticles can facilitate personalized anticancer treatment.
Probing the tautomerization of disilenes and disilabenzenes with their isomeric silylenes: significant substituent, aromaticity and base effects
Authors: Huang Yuanyuan , Wu Jiashun , Qiu Rulin , Xu Fangzhou , Zhu Jun
Published: November 2020

Theoretical calculations reveal significant effects of substituent, aromaticity and base on the tautomerization of disilenes and disilabenzenes with their isomeric silylenes.
Stability improvement of Cu(ii)-doped ZnS/ZnO photodetectors prepared with a facile solution-processing method
Authors: Hsiao Po-Hsuan , Wei Ta-Cheng , Chen Chia-Yun
Published: November 2020

The solution-processed growth of Cu2+ doped ZnS as protective coatings on ZnO nanorods with improved photoresponsivity and stability was presented.
Theory for the Casimir effect and the partitioning of active matter
Authors: Kjeldbjerg Camilla M. , Brady John F.
Published: November 2020

A theoretical model based on macroscopic momentum balances analytically predicts the Casimir effect and the partitioning of active matter.
Self‐stabilising speed regulating differential mechanism for continuously variable speed wind power generation system
Authors: Yin Wenliang , Dong Zhao Yang , Liu Lin , Rui Xiaoming
Published: November 2020

The speed regulating differential mechanism (SRDM) enables grid‐connected wind turbines (WTs) to generate constant‐frequency electric power without fully‐ or partially‐rated converters. In this study, the authors present a self‐stabilising SRDM (SS‐SRDM) consisting of a planetary gear train (PGT), a differential mechanism, and a constant speed motor for WTs to dislodge the high‐cost speed sensors, servo motor and the complicated control system from the electrical controlled SRDM. The kinematic principles and the four‐axis dynamic characteristics of SS‐SRDM are studied. An effective parameter configuration method for tuning the speed ratios of five key connection units is also proposed and used to obtain a PGT with optimal structural parameters. The detailed simulation model of a 3 MW WT with SS‐SRDM is established and then validated through physical experiments. Results show the satisfactory accuracy of the built model (maximum steady‐state errors in output shaft and speed regulating shaft are, respectively, 0.76 and 1.95%). Finally, case studies and verification work of the proposed methods are carried out, in which the rotational speed, power, speed error, and power ratio among wind rotor, SRM, and synchronous generator are obtained. Case studies well‐illustrate the availability of parameter design and the effectiveness of speed‐regulations of the proposed SS‐SRDM method.
A nonlinear solar magnetic field calibration method for the filter-based magnetograph by the residual network
Authors: Guo Jingjing , Bai Xianyong , Liu Hui , Yang Xu , Deng Yuanyong , Lin Jiaben , Su Jiangtao , Yang Xiao , Ji Kaifan
Published: November 2020

Context. The method of solar magnetic field calibration for the filter-based magnetograph is normally the linear calibration method under weak-field approximation that cannot generate the strong magnetic field region well due to the magnetic saturation effect.

Aims. We try to provide a new method to carry out the nonlinear magnetic calibration with the help of neural networks to obtain more accurate magnetic fields.

Methods. We employed the data from Hinode/SP to construct a training, validation and test dataset. The narrow-band Stokes I, Q, U, and V maps at one wavelength point were selected from all the 112 wavelength points observed by SP so as to simulate the single-wavelength observations of the filter-based magnetograph. We used the residual network to model the nonlinear relationship between the Stokes maps and the vector magnetic fields.

Results. After an extensive performance analysis, it is found that the trained models could infer the longitudinal magnetic flux density, the transverse magnetic flux density, and the azimuth angle from the narrow-band Stokes maps with a precision comparable to the inversion results using 112 wavelength points. Moreover, the maps that were produced are much cleaner than the inversion results. The method can effectively overcome the magnetic saturation effect and infer the strong magnetic region much better than the linear calibration method. The residual errors of test samples to standard data are mostly about 50 G for both the longitudinal and transverse magnetic flux density. The values are about 100 G with our previous method of multilayer perceptron, indicating that the new method is more accurate in magnetic calibration.
Non-existence of Bose–Einstein condensation in Bose–Hubbard model in dimensions 1 and 2
Authors: Stachura Piotr , Pusz Wiesław , Wojtkiewicz Jacek
Published: November 2020

We apply the Bogoliubov inequality to the Bose–Hubbard model to rule out the possibility of Bose–Einstein condensation. The result holds in one and two dimensions for any filling at any nonzero temperature. This result can be considered as complementary to the analogous, classical result known for interacting bosons in a continuum.
Recirculation zone downstream lateral expansions of open channel flow
Authors: Han L. , Riviere N. , Chatelain M. , Mignot E.
Published: November 2020

The present work combines experiments, computational fluid dynamics, and hydraulic models to explain the recirculation length variations downstream of sudden lateral expansions of an open-channel flow. This situation can be compared to the classical turbulent backward facing step situation, but the flow shallowness brings substantial differences. Experiments show that the recirculating zone length relative to the expansion width, L/d, varies in a quite wide range from 2 to 14. The expansion ratio Rb and mostly the bed friction number S influence these variations. Three dimensional numerical simulations confirm these results but also detail the role of a third parameter, the relative water depth h/d. A one dimensional hydraulic model reveals the mechanisms leading to so huge L/d variations. Finally, two dimensional depth-averaged flow equations reveal the prevailing role of bed friction for high S values. Thanks to all these results, the present paper explains the evolution of the recirculation zone length with the different parameters. The shortening of this length is caused by two different mechanisms, corresponding to two asymptotical regimes. For low bed friction numbers S and high relative water depth h/d, large-scale vortices shed from the expansion corner drive the momentum exchanges from the freestream to the recirculation. For high bed friction numbers, their role is negligible: the recirculation zone is accelerated by a velocity leveling due to bed friction, leading to L/d ∝ S−0.7.
Neutron-induced signal on the single crystal chemical vapor deposition diamond-based neutral particle analyzer
Authors: Kamio S. , Fujiwara Y. , Ogawa K. , Kobayashi M. I. , Sangaroon S. , Isobe M. , Seki R. , Nuga H. , Osakabe M. , Matsuyama S. , Miwa M. , Toyama S.
Published: November 2020

A diamond-based neutral particle analyzer (DNPA) array composed of single-crystal chemical vapor deposition (sCVD) diamond detectors was installed on the Large Helical Device (LHD) for measuring the helically trapped energetic particles. In high neutron flux experiments, the unwanted neutron-induced pulse counting rate should be estimated using the neutron diagnostics because a diamond detector is sensitive to neutrons as well as energetic neutral particles. In order to evaluate the quantitative neutron-induced pulse counting rate on the DNPA, the response functions of the sCVD diamond detector for mono-energetic neutrons were obtained using accelerator-based D–D and D–7Li neutron sources in Fast Neutron Laboratory (FNL). As a result of the neutron flux estimation by the Monte Carlo N-Particle code at the NPA position in the LHD and the response function obtained in the FNL experiment, the counting rate of the neutron-induced signal was predicted to be 1.1 kcps for the source neutron emission rate of Sn = 1 × 1015 n/s. In the LHD experiment, the neutron-induced signals were observed by closing the gate valve during the plasma discharges. It is found that the counting rates of the neutron-induced signals proportional to Sn reached 1.1 kcps at Sn = 1 × 1015 n/s. As a result of the quantitative estimation of the neutron-induced signals on the DNPA using other neutron measurements, it has become possible to accurately measure energetic neutral particles in the high neutron flux experiment.
Effect of gusty inflow on the jet-switching characteristics of a plunging foil
Authors: Majumdar Dipanjan , Bose Chandan , Sarkar Sunetra
Published: November 2020

The effect of stochastic inflow fluctuations on the jet-switching characteristics of a harmonically plunging elliptic foil at a low Reynolds number regime has been analyzed in the present study. The inflow fluctuations are generated by simulating an Ornstein–Uhlenbeck process—a stationary Gauss–Markov process—with a chosen correlation function. In the absence of fluctuations, quasi-periodic movement of the wake vortices plays a key role in bringing out jet-switching at κh ≥ 1.5. However, fluctuating inflow alters the organized arrangement of the vortex street even at a lower κh (κh = 1.0), giving way to an advanced jet-switching onset. More frequent switching with a larger deflection angle is also observed at κh = 1.5 as compared to the no fluctuation case. Effects of inflow timescales on the deflection angle and switching frequency of the wake are investigated by varying the input correlation-lengths. The underlying flow physics are investigated through a qualitative study of the near-field interactions as well as various quantitative measures derived from the unsteady flow-field.
An improved strip-line fast Faraday cup for beam bunch measurements
Authors: Mathew Jose V. , Bajaj Aman
Published: November 2020

A 3 MeV proton radio frequency quadrupole (RFQ) accelerator has been designed, built, and commissioned at the Bhabha Atomic Research Centre, India. A compact wide bandwidth strip-line fast Faraday cup (SFFC) has been developed for the beam bunch measurements of the 352 MHz RFQ. The SFFC design is improvised over the standard strip-line FFC designs with a thicker strip, which can withstand larger beam intensities. The absence of the pinhole beam limiting aperture and the provision for a suppressor electrode to suppress secondary electrons on the strip are other improvisations over standard SFFC designs. The SFFC has been characterized using the time domain reflectometry method, and a broad bandwidth of ∼7 GHz is measured. The SFFC has been tested with a 3 MeV RFQ beam at a 4 mA peak current. The time structure of the individual micro-pulses with a FWHM of 297 ps has been measured with a SFFC.
A study of fluid dynamics and human physiology factors driving droplet dispersion from a human sneeze
Authors: Fontes D. , Reyes J. , Ahmed K. , Kinzel M.
Published: November 2020

Recent studies have indicated that COVID-19 is an airborne disease, which has driven conservative social distancing and widescale usage of face coverings. Airborne virus transmission occurs through droplets formed during respiratory events (breathing, speaking, coughing, and sneezing) associated with the airflow through a network of nasal and buccal passages. The airflow interacts with saliva/mucus films where droplets are formed and dispersed, creating a route to transmit SARS-CoV-2. Here, we present a series of numerical simulations to investigate droplet dispersion from a sneeze while varying a series of human physiological factors that can be associated with illness, anatomy, stress condition, and sex of an individual. The model measures the transmission risk utilizing an approximated upper respiratory tract geometry for the following variations: (1) the effect of saliva properties and (2) the effect of geometric features within the buccal/nasal passages. These effects relate to natural human physiological responses to illness, stress, and sex of the host as well as features relating to poor dental health. The results find that the resulting exposure levels are highly dependent on the fluid dynamics that can vary depending on several human factors. For example, a sneeze without flow in the nasal passage (consistent with congestion) yields a 300% rise in the droplet content at 1.83 m (≈6 ft) and an increase over 60% on the spray distance 5 s after the sneeze. Alternatively, when the viscosity of the saliva is increased (consistent with the human response to illness), the number of droplets is both fewer and larger, which leads to an estimated 47% reduction in the transmission risk. These findings yield novel insight into variability in the exposure distance and indicate how physiological factors affect transmissibility rates. Such factors may partly relate to how the immune system of a human has evolved to prevent transmission or be an underlying factor driving superspreading events in the COVID-19 pandemic.
Oscillations in the central brain of
Drosophila
are phase locked to attended visual features
Authors: Grabowska Martyna J. , Jeans Rhiannon , Steeves James , van Swinderen Bruno
Published: November 2020

Significance

There is increasing evidence that even the smallest animal brains provide a capacity for selective attention and subjective awareness, but it is unknown if similar mechanisms might be employed as in higher animals. Recent work in insects highlights a brain structure, the central complex (CX), which could support selective attention processes. Recording from the CX of behaving flies making decisions in a virtual reality environment, we show that visual selection is achieved by phase-controlled endogenous 20- to 30-Hz oscillations that lock onto temporal features of attended visual objects. This suggests an oscillation-driven binding mechanism in the insect brain that employs a similar beta frequency range as has been observed for feature binding in humans.
Micromilling of Ti6Al4V alloy assisted by plasma electrolytic oxidation
Authors: Hu Yizhong , Meng Jianbing , Luan Xiaosheng , Dong Xiaojuan , Zhou Haian , Qu Linghui , Zhang Hongwei , Wei Xiuting
Published: November 2020

This paper develops a novel processing method of plasma electrolytic oxidation-assisted micromilling (PEOAM). Electrolyte solutions with KH2PO4, NaAlO2, or Na2SiO3 as the main component are designed, and three types of oxide films are grown on the surface of a Ti6Al4V alloy in situ by means of plasma electrolytic oxidation. The morphology and composition of the oxide films are characterized by scanning electron microscope and energy dispersive spectrum. Additionally, the cutting force and surface roughness of PEOAM are measured by dynamometer and white light interferometer, respectively. A comparison between PEOAM and conventional micromilling in terms of cutting force, tool wear, chips, and surface roughness is conducted, with results showing that oxide films with about 20 μm thickness are loose and porous, their hardness decreasing to a minimum of 1.12 GPa, which corresponds to 23.3% of the original hardness value. At the axial cutting depth of 18 μm, compared to the Fx, Fy
, and Fz
values of the Ti6Al4V alloy substrate, the average milling forces of the NaAlO2 oxide film are the most significantly reduced (35.1%, 15.7%, and 94.8% of the original values, respectively). At the axial cutting depth of 25 μm, the surface roughness (R
a) value of PEOAM is reduced by 0.08–0.12 μm. Consequently, under the same cutting parameters, PEOAM can effectively reduce the cutting force, prolong the service life of the tool, and improve surface quality.
Bichromatically-controlled entanglement between asymmetric quantum dots in a photonic cavity
Authors: Antón M A , Gonzalo I , Carreño F
Published: November 2020

Entanglement generation and control of two spatially separated asymmetric quantum dots with broken inversion symmetry and mediated by a photonic cavity is studied using a quantum master equation formalism. The quantum dots are coherently driven by a bichromatic laser consisting of a strong optical field nearly resonant with the optical transition of each quantum dot, and a low frequency field. The optical field dresses each quantum dot, and due to the presence of large permanent dipole moments in the quantum dots they are coupled by the low frequency field. We make use of the generated dressed-state scheme for entanglement control. The master equation which describes the interaction with the cavity modes and the coherent fields is numerically solved. In order to gain some insight on the role of the external parameters on entanglement, an effective Hamiltonian for the atomic subsystem is derived in the dressed state representation by adiabatically eliminating the cavity field operators. It is found that steady-state entanglement can be controlled by means of the amplitude and frequency of the low frequency field.
Prediction of thermally induced failure for electronic equipment based on an artificial olfactory system
Authors: Ma Denglong , Liu Yuan , Zheng Liangtian , Gao Jianmin , Gao Zhiyong , Zhang Zaoxiao
Published: November 2020

The failure of electronic equipment causes serious consequences and even catastrophic fires. Abnormal thermal signals are one of the main characteristics of the failure of electronic equipment. Thus, a new method for recognizing and predicting the thermally induced failure states of electronic equipment was proposed, based on an artificial olfactory system (AOS). The AOS recognizes the state of the volatile components released during the early stages of thermally induced failure and uses it to predict the state of health of the electronic equipment. Some typical electronic devices, such as microcomputer units, electronic rectifiers, transformers, and battery modules, were tested with the AOS to recognize the failures indicated by abnormal thermal accumulation. Compared with infrared thermal imagers and gas analyzers, the PEN3 electronic nose was utilized to monitor the status of the devices under different thermal failure scenarios. It was found that infrared thermal imaging was only able to monitor the local surface temperature, and the air temperature in the device chamber changed slowly with the surface temperature of the electronic modules. However, the AOS was able to detect the abnormal change in the whole chamber. Linear discriminant analysis (LDA) and principal component analysis (PCA) were then adopted to investigate the features of thermally induced failure for different thermal states. The results showed that the models obtained both from LDA and PCA were able to distinguish the different states of the electronic devices. Furthermore, a support vector machine model was built, based on the AOS data, to recognize and predict the thermally induced failure processes. All the failure states of the electronic devices caused by thermal simulations were recognized successfully and the prediction accuracy was above 95%. Hence, the experimental results of this research proved that using the AOS, it is feasible to predict the thermally induced failure states of electronic equipment, and the failure of electronic devices can be forecast in advance, before the obvious temperature rise and smoke release. Moreover, the method proposed in this research can also be applied to the prediction of, and warning about, electrical fires, indoor fires, and other thermally induced accidents.
Molecular dynamics simulation for interfacial properties of carbon nanotube reinforced aluminum composites
Authors: Patel Pramod Rakt , Sharma Sumit , Tiwari S K
Published: November 2020

A molecular dynamics (MD) simulation method has been used to predict the interfacial behavior of single-wall carbon nanotube (CNT) reinforced aluminum (Al) composites. At the interface of the CNT and the Al, only van der Waals interaction was considered. The effect of CNT volume fraction and chirality on CNT pull-out has been studied for the first time with a proper distinction between them. The length of all the CNTs was kept constant throughout the study. The approach used in this work was validated with an earlier study. The present study revealed that the average pull-out load was found proportional to both the CNT volume fraction as well as the diameter. The smaller diameter CNTs improved the interfacial shear strength (ISS) at lower volume fraction significantly in comparison to that of the larger diameter CNTs. The highest improvement of 38.7% was observed in the ISS during pull-out of (6, 6) CNT at a CNT volume fraction of 3.17%. The average energy increment was found to be increasing with CNT volume fraction and was higher for larger diameter CNTs.
The unique global solvability and optimal time decay rates for a multi-dimensional compressible generic two-fluid model with capillarity effects
*
Authors: Xu Fuyi , Chi Meiling
Published: November 2020

The present paper deals with the Cauchy problem of a compressible generic two-fluid model with capillarity effects in any dimension N ⩾ 2. We first study the unique global solvability of the model in spaces with critical regularity indices with respect to the scaling of the associated equations. Due to the presence of the capillary terms, we exploit the parabolic properties of the linearized system for all frequencies which enables us to apply contraction mapping principle to show the unique global solvability of strong solutions close to a stable equilibrium state. Furthermore, under a mild additional decay assumption involving only the low frequencies of the data, we establish the optimal time decay rates for the constructed global solutions.
Global existence of the nonisentropic compressible Euler equations with vacuum boundary surrounding a variable entropy state
Authors: Rickard Calum , Hadžić Mahir , Jang Juhi
Published: November 2020

Global existence for the nonisentropic compressible Euler equations with vacuum boundary for all adiabatic constants γ > 1 is shown through perturbations around a rich class of background nonisentropic affine motions. The notable feature of the nonisentropic motion lies in the presence of non-constant entropies, and it brings a new mathematical challenge to the stability analysis of nonisentropic affine motions. In particular, the estimation of the curl terms requires a careful use of algebraic, nonlinear structure of the pressure. With suitable regularity of the underlying affine entropy, we are able to adapt the weighted energy method developed for the isentropic Euler Hadžić and Jang (2018 Inventiones Mathematicae
214 1205–1266) to the nonisentropic problem. For large γ values, inspired by Shkoller and Sideris (2019 Arch. Ration. Mech. Anal.
234 115), we use time-dependent weights that allow some of the top-order norms to potentially grow as the time variable tends to infinity. We also exploit coercivity estimates here via the fundamental theorem of calculus in time variable for norms which are not top-order.
Signal intensity form of the Tofts model for quantitative analysis of prostate dynamic contrast enhanced MRI data
Authors: Fan Xiaobing , Chatterjee Aritrick , Medved Milica , Oto Aytekin , Karczmar Gregory S
Published: November 2020

The aim of this study is to develop a signal intensity (S(t)) form of the standard Tofts pharmacokinetic model that avoids the need to calculate tissue contrast agent concentration (C(t)) as function of time (t). We refer to this as ‘SI-Tofts’ model. Physiological parameters (K
trans and v
e) calculated using the SI-Tofts and standard Tofts models were compared by using simulations and human prostate dynamic contrast enhanced (DCE) MRI data. This approach was also applied to the Patlak model to compare K
trans values calculated from C(t) and S(t). Simulations were performed on DCE-MRI data from the quantitative imaging biomarkers alliance to validate SI-Tofts model. In addition, ultrafast DCE-MRI data were acquired from 18 prostate cancer patients on a Philips Achieva 3T-TX scanner. Regions-of-interest (ROIs) for prostate cancer, normal tissue, gluteal muscle, and iliac artery were manually traced. The C(t) was calculated for each ROI using the standard model with measured pre-contrast tissue T
1 values. Both the simulation and clinical results showed strong correlation (r = 0.87–0.99, p < 0.001) for K
trans and v
e calculated from the SI-Tofts and standard Tofts models. The SI-Tofts model with a correction factor using the T
1 ratio of blood to tissue significantly improved the K
trans estimates. The correlation of K
trans obtained from the Patlak model with C(t) vs S(t) was also strong (r = 0.95–0.99, p < 0.001). These preliminary results suggest that physiological parameters from DCE-MRI can be reliably estimated from the SI-Tofts model without contrast agent concentration calculation.
Experimental determination of magnetic field correction factors for ionization chambers in parallel and perpendicular orientations
Authors: Pojtinger Stefan , Nachbar Marcel , Ghandour Sarah , Pisaturo Olivier , Pachoud Marc , Kapsch Ralf-Peter , Thorwarth Daniela
Published: November 2020

Magnetic field correction factors are needed for absolute dosimetry in magnetic resonance (MR)-linacs. Currently experimental data for magnetic field correction factors, especially for small volume ionization chambers, are largely lacking. The purpose of this work is to establish, independent methods for the experimental determination of magnetic field correction factors

 

k

B
⃗

,
Q

in an orientation in which the ionization chamber is parallel to the magnetic field. The aim is to confirm previous experiments on the determination of Farmer type ionization chamber correction factors and to gather information about the usability of small-volume ionization chambers for absolute dosimetry in MR-linacs. The first approach to determine

 

k

B
⃗

,
Q

is based on a cross-calibration of measurements using a conventional linac with an electromagnet and an MR-linac. The absolute influence of the magnetic field in perpendicular orientation is quantified with the help of the conventional linac and the electromagnet. The correction factors for the parallel orientation are then derived by combining these measurements with relative measurements in the MR-linac. The second technique utilizes alanine electron paramagnetic resonance dosimetry. The alanine system as well as several ionization chambers were directly calibrated with the German primary standard for absorbed dose to water. Magnetic field correction factors for the ionization chambers were determined by a cross-calibration with the alanine in an MR-linac. Important quantities like

 

k

B
⃗

,
Q

 

for Farmer type ionization chambers in parallel orientation and the change of the dose to water due the magnetic field

c

B
⃗

have been confirmed. In addition, magnetic field correction factors have been determined for small volume ionization chambers in parallel orientation. The electromagnet-based measurements of

 

k

B
⃗

,
Q

for

7

MV

/

1.5

T

MR-linacs and parallel ionization chamber orientations resulted in 0.9926(22), 0.9935(31) and 0.9841(27) for the PTW 30013, the PTW 31010 and the PTW 31021, respectively. The measurements based on the second technique resulted in values for

 

k

B
⃗

,
Q

of 0.9901(72), 0.9955(72), and 0.9885(71). Both methods show excellent accuracy and reproducibility and are therefore suitable for the determination of magnetic field correction factors. Small-volume ionization chambers showed a variation in the resulting values for

 

k

B
⃗

,
Q

and should be cross-calibrated instead of using tabulated values for correction factors.
Bronchoscope motion tracking using centerline-guided Gaussian mixture model in navigated bronchoscopy
Authors: Navaei Lavasani Saeedeh , Farnia Parastoo , Najafzadeh Ebrahim , Saghatchi Samaneh , Samavati Mehdi , Abtahi Hamidreza , Deevband Mohammadreza , Ahmadian Alireza
Published: November 2020

Electromagnetic-based navigation bronchoscopy requires accurate and robust estimation of the bronchoscope position inside the bronchial tree. However, respiratory motion, coughing, patient movement, and airway deformation inflicted by bronchoscope significantly hinder the accuracy of intraoperative bronchoscopic localization. In this study, a real-time and automatic registration procedure was proposed to superimpose the current location of the bronchoscope to corresponding locations on a centerline extracted from bronchial computed tomography (CT) images. A centerline-guided Gaussian mixture model (CG-GMM) was introduced to register a bronchoscope’s position concerning extracted centerlines. A GMM was fitted to bronchoscope positions where the orientation likelihood was chosen to assign the membership probabilities of the mixture model, which led to preserving the global and local structures. The problem was formulated and solved under the expectation maximization framework, where the feature correspondence and spatial transformation are estimated iteratively. Validation was performed on a dynamic phantom with four different respiratory motions and four human real bronchoscopy (RB) datasets. Results of the experiments conducted on the bronchial phantom showed that the average positional tracking error using the proposed approach was equal to 1.98

±

0.98 mm that was reduced in comparison with independent electromagnetic tracking (EMT), iterative closest point (ICP), and coherent point drift (CPD) methods by 64%, 58%, and 53%, respectively. In the patient assessment part of the study, the average positional tracking error was 4.73

±

4.76 mm and compared to ICP, and CPD methods showed 31.4% improvement of successfully tracked frames. Our approach introduces a novel method for real-time respiratory motion compensation that provides reliable guidance during bronchoscopic interventions and, thus could increase the diagnostic yield of transbronchial biopsy.
Spatio-temporal dynamics of a nanosecond pulsed microwave plasma ignited by time reversal
Authors: Valentin Mazières , Pascaud Romain , Pascal Olivier , Clergereaux Richard , Stafford Luc , Dap Simon , Liard Laurent
Published: November 2020

In the present paper, a detailed investigation of the spatio-temporal dynamics of the recently developed time reversal microwave plasma source is presented. This novel source allows to ignite a plasma at a desired location in a reverberant cavity by focusing the electromagnetic energy in time and space. An important feature is the possibility to control the plasma position only by changing the input microwave waveform. The source is operated in a repetitive pulsed mode with very low duty cycle (typically 5 × 10−2%). Nanosecond pulses have rise time lower than 1 ns. The generated plasmas have typical sizes in the millimeter range and are observed using imaging for dozens of nanoseconds. The plasma behavior is investigated for different pressures and repetition frequencies. A strong dependence is observed between each discharge pulse suggesting the existence of an important memory effect. The latter is probably due to argon metastable atoms and/or residual charges remaining in the post-discharge and allowing the next breakdown to occur at a moderate electric field.
A metamaterial for wearable piezoelectric energy harvester
Authors: Gao Shanshi , Gain Asit Kumar , Zhang Liangchi
Published: November 2020

In this study, a metamaterial is developed and manufactured by additive manufacturing technique for a novel wearable piezoelectric energy harvester (PEH). This PEH converts electricity from the kinetic energy associated with walking by attached polyvinylidene fluoride (PVDF) membranes. Finite element method analysis was conducted to simulate the dynamic compression on insoles corresponding to actual walking or running. The simulation results were verified by experiments. It was found that a triple-layer PVDF structure can produce an output voltage of 4.15 V and one insole with a triple-layer PVDF structure array can provide an 8.6 mW output power at running.
The flow of fluid-particle suspension between two rotating stretchable disks with the effect of the external magnetic field
Authors: Radhika M , Sowmya G , Siddabasappa  , Prasannakumara B C , Alam Manawwer , Rahimi-Gorji Mohammad , Rahaman Mostafizur
Published: November 2020

This paper explores the compressible dusty fluid flow between two spinning disks. The upper and lower disks rotate at an angular velocity equal to

Ω

1

and

Ω

2

respectively. Fluid and dust particles are considered to be dispersed axisymmetrically. The equations which represents the described flow are transformed into a set of ordinary differential equations which are nonlinear and coupled by opting suitable similarity variables. These equations are solved using the built-in bvp4c algorithm of MATLAB. The profiles of axial, radial, azimuthal velocity and thermal profiles are discussed through graphs for variations of non-dimensional parameters. It has been observed that the friction factor enhances with the upsurge in values of Hartmann number Ha and the Nusselt number declines for shoot up values of Eckert number. Also, the stretching parameter amplifies the friction factor and the Nusselt number.
Noise and the molecular processes underlying cell fate decision-making
Authors: Guillemin Anissa , Stumpf Michael P H
Published: November 2020

Cell fate decision-making events involve the interplay of many molecular processes, ranging from signal transduction to genetic regulation, as well as a set of molecular and physiological feedback loops. Each aspect offers a rich field of investigation in its own right, but to understand the whole process, even in simple terms, we need to consider them together. Here we attempt to characterise this process by focussing on the roles of noise during cell fate decisions. We use a range of recent results to develop a view of the sequence of events by which a cell progresses from a pluripotent or multipotent to a differentiated state: chromatin organisation, transcription factor stoichiometry, and cellular signalling all change during this progression, and all shape cellular variability, which becomes maximal at the transition state.
Dust acoustic rogue waves of fractional-order model in dusty plasma
Authors: Sun Jun-Chao , Zhang Zong-Guo , Dong Huan-He , Yang Hong-Wei
Published: November 2020

In this paper, the fractional-order model is used to study dust acoustic rogue waves in dusty plasma. Firstly, based on control equations, the multi-scale analysis and reduced perturbation method are used to derive the (3+1)-dimensional modified Kadomtsev–Petviashvili (MKP) equation. Secondly, using the semi-inverse method and the fractional variation principle, the (3+1)-dimensional time-fractional modified Kadomtsev–Petviashvili (TF-MKP) equation is derived. Then, the Riemann–Liouville fractional derivative is used to study the symmetric property and conservation laws of the (3+1)-dimensional TF-MKP equation. Finally, the exact solution of the (3+1)-dimensional TF-MKP equation is obtained by using fractional order transformations and the definition and properties of Bell polynomials. Based on the obtained solution, we analyze and discuss dust acoustic rogue waves in dusty plasma.
Newtonian gravitational constant measurement. All atomic variables become extreme when using a source mass consisting of three or more parts
Authors: Dubetsky B
Published: November 2020

Atomic interferometry methods used to measure the Newtonian gravitational constant. To improve the accuracy, one should measure the phase of an atomic interferometer at extreme values of atomic vertical velocities and coordinates. Owing to symmetry, the horizontal components of atomic velocities and coordinates are also extreme. We propose using a source mass consisting of three or more parts, since only in this case one can find such an arrangement of parts that all atomic variables become extreme. Nonlinear dependences of the phase on the uncertainties of atomic positions and velocities near those extreme values required us to modify the expression for the phase relative standard deviation. Moreover, taking into account nonlinear terms in the phase dependence on the atomic coordinates and velocities leads to a phase shift. In the last experiment to measure the Newtonian gravitational constant by atomic interferometry, this shift was not included. We took the shift into account, got a value of 199 ppm for it, and this leads to a decrease in the value of the Newton constant by 0.02%. In addition, we showed that at equal sizes of the atomic cloud in the vertical and horizontal directions, as well as at equal atomic vertical and transverse temperatures, systematic errors due to the finite size and temperature of the cloud disappear. The calculation also showed that when using the 13-ton source mass proposed recently, the measurement accuracy can reach 17 ppm for a source mass consisting of four quarters. We assumed that the source mass consisting of a set of cylinders is used for measurements. We have obtained a new analytical expression for the gravitational field of a homogeneous cylinder.
Invited Commentary: Epigenetic Clocks and Obesity—Towards the Next Frontier Using Integrative Approaches and Early-Life Models
Authors: Tekola-Ayele Fasil
Published: November 2020

Why people of the same age show differences in age-related functional decline and whether biological aging can be slowed down through lifestyle changes and therapeutics are active research topics. Molecular tools that predict biological age based on DNA methylation markers, known as epigenetic clocks, are facilitating these efforts. In this issue, Kresovich et al. (Am J Epidemiol. 2021;190(6):984–993) investigated a cohort of non-Hispanic White women, demonstrating positive relationships between adiposity measures and the ticking rate of epigenetic clocks in blood. This commentary emphasizes that integrating molecular and genetic epidemiology approaches is crucial to dissecting the complex relationship between obesity and epigenetic aging. The early-life period is explored as a unique opportunity to gain novel insights into links between developmental processes and aging in later life. Last, the landscape of the next frontier in aging research is described in light of the imperative for transdisciplinary approaches to outline a shared vision and public health implementation dilemmas.
Type II achalasia is associated with a comparably favorable outcome following per oral endoscopic myotomy
Authors: Tomizawa Yutaka , Mahmud Nadim , Dasher Kevin , Triggs Joseph R , Saumoy Monica , Falk Gary W , Ginsberg Gregory G
Published: November 2020

Per oral endoscopic myotomy (POEM) is a safe and effective treatment for esophageal motility disorder in treatment-naïve patients as well as salvage therapy. Though type II achalasia, compared to other subtypes, is reported to have a more favorable outcome with pneumatic dilation (PD) or Heller myotomy (HM), it is unclear whether achalasia subtype predicts symptom response to POEM. We aimed to evaluate whether type II achalasia is associated with a comparably favorable outcome following POEM. We performed a retrospective review of patients with esophageal motility disorder who were referred for POEM from April 2014 to June 2017. The main outcome was clinical success based on Eckardt score ≤3 and its association with subtype and safety. A total of 63 patients (mean age 51 years [SD 15]; 63% male) underwent a total of 68 POEMs with median of 263 days follow-up. Of these, 45 (71.3%) patients were type II achalasia. In all, 29 (46%) patients were treatment-naïve and 34 (54%) patients had previous endoscopic or surgical therapy including botulinum toxin injection in 16 (25%), PD in 10 (16%), both botulinum toxin injection and PD in 8 (13%) and HM in 3 (5%). Technical success was 100% and clinical success was achieved in 51 (81%) patients. The rate of clinical success was higher in patients with type II achalasia compared to the other subtypes (88.9% vs. 61.1% [P = 0.028]) and type II achalasia patients required fewer redo POEM (2.2% vs. 22.2% [P = 0.021]). Multivariate logistic regression analysis demonstrated the positive prediction of clinical success for type II achalasia following POEM (P = 0.046). As observed with PD and HM, type II achalasia was associated with a favorable clinical outcome following POEM.
D-EE: Distributed software for visualizing intrinsic structure of large-scale single-cell data
Authors: An Shaokun , Huang Jizu , Wan Lin
Published: November 2020

Background

Dimensionality reduction and visualization play vital roles in single-cell RNA sequencing (scRNA-seq) data analysis. While they have been extensively studied, state-of-the-art dimensionality reduction algorithms are often unable to preserve the global structures underlying data. Elastic embedding (EE), a nonlinear dimensionality reduction method, has shown promise in revealing low-dimensional intrinsic local and global data structure. However, the current implementation of the EE algorithm lacks scalability to large-scale scRNA-seq data.

Results

We present a distributed optimization implementation of the EE algorithm, termed distributed elastic embedding (D-EE). D-EE reveals the low-dimensional intrinsic structures of data with accuracy equal to that of elastic embedding, and it is scalable to large-scale scRNA-seq data. It leverages distributed storage and distributed computation, achieving memory efficiency and high-performance computing simultaneously. In addition, an extended version of D-EE, termed distributed optimization implementation of time-series elastic embedding (D-TSEE), enables the user to visualize large-scale time-series scRNA-seq data by incorporating experimentally temporal information. Results with large-scale scRNA-seq data indicate that D-TSEE can uncover oscillatory gene expression patterns by using experimentally temporal information.

Conclusions

D-EE is a distributed dimensionality reduction and visualization tool. Its distributed storage and distributed computation technique allow us to efficiently analyze large-scale single-cell data at the cost of constant time speedup. The source code for D-EE algorithm based on C and MPI tailored to a high-performance computing cluster is available at https://github.com/ShaokunAn/D-EE.