bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Prospective Study on Acute Subdural Hematoma in Mild Head Injury Patients: Outcome with Initial Nonoperative Management
Authors: Barooah R. K , Haloi Hriday , Baishya B. K. , Sarma Kishore 
Published: July 2019

Abstract
Introduction Incidence of acute subdural hematoma (SDH) is 21% in head injury patients. Decompressive craniectomy done for acute SDH itself carries a very high morbidity and mortality. The skull bone defect, prolonged hospital stay, the need of a second surgery (cranioplasty), and bone flap infection are other problems associated with decompressive craniectomy. Hence, this study looks into the outcome of conservative management in acute SDH in patients with mild head injury.
Aims and Objectives The main objective of this article is to study the patients included in the study with regard to outcome, morbidity, duration of hospital stay, and hospital cost. This article also studies the efficacy and outcome of lesser aggressive management (burr-hole evacuation) after initial nonoperative management of the patients included in the study.
Materials and Methods This is a prospective study performed in the Department of Neurosurgery, Gauhati Medical College and Hospital. A total of 30 patients arriving in the emergency department during a 6-month period from December 1, 2017 to May 31, 2018 with a diagnosis of acute SDH and with Glasgow coma scale (GCS) 13 to 15 were evaluated. Evaluation was done by history, clinical examination, GCS, computed tomography (CT) (plain) scan brain, and Glasgow outcome score at 6 months follow-up.
Results and Observations Twenty patients showed complete resolution of the clot, and eight patients had liquefaction of clot which was evacuated by burr-hole. One mortality was recorded and one had to undergo decompressive craniectomy. About 93.33% of patients managed by initial nonoperative management showed functionally independent outcome at 6 months follow-up.
Conclusion Conservative management in patients with acute SDH can be a viable alternative in certain cases. Those patients with GCS of 13 and above with CT scan showing midline shift of even ≥5 mm or thickness of 10 mm and more can also be managed conservatively by close monitoring.
Ovarian Sertoli-Leydig Cell Tumors: Epidemiological, Clinical and Prognostic Factors
Authors: Castro Beatriz Guerreiro Ruiz , Souza Cristiano de Pádua , Andrade Carlos Eduardo Mattos da Cunha , Vieira Marcelo de Andrade , Andrade Diocésio Alves Pinto de , Reis Ricardo dos 
Published: July 2019

Objective To describe a series of cases of ovarian Sertoli-Leydig cell tumors (SLCTs).
Methods Retrospective review of 12 cases of SLCT treated at the Hospital do Câncer de Barretos, Barretos, state of São Paulo, Brazil, between October 2009 and August 2017.
Results The median age of the patients was 31 years old (15–71 years old). A total of 9 patients (75.0%) presented symptoms: 8 (66.7%) presented with abdominal pain, 5 (41.7%) presented with abdominal enlargement, 2 (16.7%) presented with virilizing signs, 2 (16.7%) presented with abnormal uterine bleeding, 1 (8.3%) presented with dyspareunia, and 1 (8.3%) presented with weight loss. The median preoperative lactate dehydrogenase (LDH) was 504.5 U/L (138–569 U/L), alpha-fetoprotein (AFP) was 2.0 ng/ml (1.1–11.3 ng/ml), human chorionic gonadotropin (β-hCG) was 0.6 mUI/ml (0.0–2.3 mUI/ml), carcinoembryonic antigen (CEA) was 0.9 ng/ml (0.7–3.4 ng/ml), and cancer antigen 125 (CA-125) was 26.0 U/ml (19.1–147.0 U/ml). All of the tumors were unilateral and surgically treated. Lymphadenectomy was performed in 3 (25.0%) patients, but none of the three patients submitted to lymphadenectomy presented lymph node involvement. In the anatomopathological exam, 1 (8.3%) tumor was well-differentiated, 8 (66.7%) were moderately differentiated, and 3 (25.0%) were poorly differentiated. A total of 5 (55.6%) tumors were solid-cystic, 2 (22.2%) were purely cystic, 1 (11.1%) was cystic with vegetations, and 1 (11.1%) was purely solid, but for 3 patients this information was not available. The median lesion size was 14.2 cm (3.2–23.5 cm). All of the tumors were at stage IA of the 2014 classification of the International Federation of Gynecology and Obstetrics (FIGO). A total of 2 (16.7%) patients received adjuvant treatment; 1 of them underwent 3 cycles of paclitaxel and carboplatin every 21 days, and the other underwent 4 cycles of ifosfamide, cisplatin and etoposide every 21 days. None of all of the patients had recurrence, and one death related to complications after surgical staging occurred.
Conclusion Abdominal pain was the most frequent presentation. There was no ultrasonographic pattern. All of the SLCTs were at stage IA, and most of them were moderately differentiated. Relapses did not occur, but one death related to the surgical staging occurred.
Ultrasound Monitoring after Pelvis-Sparing Dismembered Pyeloplasty: High Sensitivity and Low Specificity for the Success of Operation
Authors: Kiblawi Rim , Kuebler Joachim F. , Petersen Claus , Ure Benno M. , Hofmann Alejandro D. 
Published: July 2019

Abstract
Introduction A decrease in the anteroposterior diameter (APD) of the renal pelvis on ultrasound has been postulated to be indicative of sufficient pelvic drainage after pyeloplasty. Traditionally, pyeloplasty is combined with a reduction of the renal pelvis. We have recently demonstrated that resection of the pelvis during pyeloplasty is not necessary. We aimed to evaluate the efficacy of ultrasound APD measurements during follow-up to identify sufficient pelvic drainage in these patients.
Materials and Methods Data from children (0–16 years) who underwent pelvis-sparing pyeloplasty in our institution from 2007 to 2018 were analyzed retrospectively. We included only those patients for whom pre- and postoperative ultrasound and renal scan data were available. Patients with a decrease versus patients with an increase in APD were analyzed with regard to urinary drainage and reoperation.
Results Seventy-three patients who underwent follow-up at a mean of 3 months after operation were included; 61 showed a decrease in APD. Renal scan showed sufficient urinary drainage in 58 of them, with none requiring reoperation. Twelve patients had an increase in APD. Six of these showed free urinary drainage on renal scan; another six showed insufficient drainage, of whom five required reoperation. The positive predictive value of a decrease in APD was 1, and the negative predictive value of increase in APD was 0.42.
Conclusion To our knowledge, this is the first study evaluating the efficacy of ultrasound measurements to identify patients with decompensated urinary drainage during early follow-up after pyeloplasty with pelvis sparing. Post- versus preoperative decrease in renal pelvis diameter appears to be sufficient to rule out recurrence of obstruction. Renal scan seems to be indicated only in cases with post- versus preoperative increase in the APD of the renal pelvis on ultrasound.
Characteristics of prosthetic vision in rats with subretinal flat and pillar electrode arrays
Authors: Ho Elton , Lei Xin , Flores Thomas , Lorach Henri , Huang Tiffany , Galambos Ludwig , Kamins Theodore , Harris James , Mathieson Keith , Palanker Daniel 
Published: July 2019

Abstract

Objective. Retinal prostheses aim to restore sight by electrically stimulating the surviving retinal neurons. In clinical trials of the current retinal implants, prosthetic visual acuity does not exceed 20/550. However, to provide meaningful restoration of central vision in patients blinded by age-related macular degeneration (AMD), prosthetic acuity should be at least 20/200, necessitating a pixel pitch of about 50 µm or lower. With such small pixels, stimulation thresholds are high due to limited penetration of electric field into tissue. Here, we address this challenge with our latest photovoltaic arrays and evaluate their performance in vivo. Approach. We fabricated photovoltaic arrays with 55 and 40 µm pixels (a) in flat geometry, and (b) with active electrodes on 10 µm tall pillars. The arrays were implanted subretinally into rats with degenerate retina. Stimulation thresholds and grating acuity were evaluated using measurements of the visually evoked potentials (VEP). Main results. With 55 µm pixels, we measured grating acuity of 48  ±  11 µm, which matches the linear pixel pitch of the hexagonal array. This geometrically corresponds to a visual acuity of 20/192 in a human eye, matching the threshold of legal blindness in the US (20/200). With pillar electrodes, the irradiance threshold was nearly halved, and duration threshold reduced by more than three-fold, compared to flat pixels. With 40 µm pixels, VEP was too low for reliable measurements of the grating acuity, even with pillar electrodes. Significance. While being helpful for treating a complete loss of sight, current prosthetic technologies are insufficient for addressing the leading cause of untreatable visual impairment—AMD. Subretinal photovoltaic arrays may provide sufficient visual acuity for restoration of central vision in patients blinded by AMD.
On the use of entangled wire materials in pre-tensioned rocking columns
Authors: Ahmadi E , Kashani M M 
Published: July 2019

Abstract
This research explores potential application of entangled wire materials as intermediate layers between segments of pre-tensioned segmental bridge columns. An ensemble of free-decay vibration tests was conducted on small-scale columns with various configurations of intermediate layers. Wooden blocks were used for segments and the entire system was tightened together using a pre-tensioned steel tendon. Damping and frequency of the columns were determined and compared. It is demonstrated that entangled wire materials substantially increase total damping of the entire system in rocking. This result is very encouraging for future application of entangled wire materials in testing large-scale pre-tensioned segmental bridge columns. However, shear and axial stiffness of the layers require further improvement to reduce their large shear and axial deformations.
Identification of modal parameters in a lightly damped system based on impact vibration testing: Application of exponential window and removal of its effect
Authors: Tajiri Daiki , Matsubara Masami , Kawamura Shozo 
Published: July 2019

Abstract
The experimental environments for impact tests are simple to construct compared to other vibration tests in experimental modal analysis. However, given that sufficient sampling time is necessary for the response to attenuate, the following two problems arise: The first is that work efficiency is lowered. The second is that the measurement time increases, which makes it more susceptible to noise. To solve these problems, it is common to shorten the sampling time and apply an exponential window to reduce the leakage error of the frequency response function (FRF). Although studies on the influence on the FRF exist, identification accuracy for damping characteristic and the influence on the residue have not discussed. In this study, the influence on the modal properties obtained and the accuracy of the results are clarified using numerical examples based on a circle fit and method using simultaneous equations of the real and imaginary parts of the FRF. Finally, the identification results were compared and made sure that the method using simultaneous equations of the real and imaginary parts of FRF can identify modal properties with high accuracy. This method is effective for improving the working efficiency and reducing the influence of noise.
Vibration characteristics of an operating ball mill
Authors: Yoshida T , Kuratani F , Ito T , Taniguchi K 
Published: July 2019

Abstract
A ball mill, which is used to finely grind materials, causes high levels of vibration and sound during grinding operations. The vibration and sound of mills provide significant information about the internal conditions and can be used to estimate the status of the ground material. We developed a simulation model for the vibration of a mill wall to better understand the relationship between the operating conditions and wall vibration characteristics. The discrete element method can be used to predict the motion of the contents, which are grinding balls and material particles, and estimate the collision force between the balls and the mill wall. A finite element method vibration analysis is performed to calculate the time history response of the vibration from the estimated collision force by DEM. Simulations and experiments are performed to evaluate the influence of changing material particle diameter on the vibration characteristics. The results of experiments and simulations show the same tendencies. A decrease in material diameter reduces the vibration velocity of the mill. The developed simulation is useful for understanding the vibration characteristics of the mill because it could obtain information, such as individual particle element velocities, that is not available from the experiments.
Modelling of a train seat with subject exposed to lateral, vertical and roll vibration
Authors: Wu Jun , Qiu Yi 
Published: July 2019

Abstract
Considering the characteristics of ride vibration of a train, a multi-body dynamic model of a double-unit passenger seat exposed to lateral, vertical and roll vibrations was developed and calibrated using measured seat transmissibilities from the acceleration at the floor to the accelerations at both the seat pan and backrest in lateral, vertical and roll directions. With use of an existing seated human model, two coupled models of the double-unit seat with one and two subjects were then developed and calibrated using the corresponding measured seat transmissibilities. The models showed good agreement with the experimental data. Using these models, modal analysis was conducted to find out the modal properties of the human-seat system and facilitate discussions in relation to the resonances in the seat transmissibilities. It was found the primary peak in the vertical transmissibility of the seat pan may arise from the mode of human body. Two vibration modes around 15 and 30 Hz of the seat contributed to the peaks with approximate frequencies in the seat transmissibilities.
Free vibration of spring-mounted beams
Authors: Vijay Kumar S , Sarkar Abhijit , Padmanabhan Chandramouli 
Published: July 2019

Abstract
In the present work, free vibration characteristics of a spring-mounted beam is studied. The objective is to determine the natural frequencies and mode shapes of this beam. Towards this end, a novel semi-analytical method is developed. The methodology is based on Green’s function of Euler-Bernoulli beam together with a Rayleigh-Ritz method. A minimal set of basis functions for the Rayleigh-Ritz method is found, by generating the beam mode shapes for extreme values (zero and infinity) of the connecting spring stiffnesses. Thus, for a beam with n intermediate spring connections, 2
n
beam modes are generated as basis functions. The Green’s function approach is used to extract the beam mode shapes for the extreme values of the connecting spring stiffnesses. The results from the proposed formulation are compared with those from a finite element (FE) simulation. For most cases, the results obtained by the two methods are in excellent agreement. Guidelines for further improvement of the accuracy of the present results have been proposed. Detailed parametric studies on the effect of spring stiffness value and their location have been performed.
Investigation of the inerter-based dynamic vibration absorber for machining chatter suppression
Authors: Dogan Hakan , Sims Neil D , Wagg David J 
Published: July 2019

Abstract
This study proposes a novel approach to increase the chatter stability in machining operations. It shows the potential performance improvement when an inerter-based dynamic vibration absorber is employed in a machining operation. Tuned inerter based devices have been employed to decrease the magnitude of the vibrations in applications such as civil engineering structures and vehicle suspension systems but the nature of chatter in machining is different from these applications. Therefore, it requires a different tuning methodology to obtain the optimal design parameters. In this study, the machining operation is modelled as an undamped single degree of freedom system and different configurations of an inerter, a damper and two springs are used to ensure a stable region of operation. Strategies for the tuning parameters are developed both analytically and numerically. Using these techniques the performance improvement in the chatter stability provided by using inerter based devices instead of a traditional dynamic vibration absorber is demonstrated.
Tuning of Parametric Excitation for Rotor Balancing
Authors: Mendes Ricardo Ugliara , Dohnal Fadi 
Published: July 2019

Abstract
Residual unbalance is the primary source of vibration in rotating machines. In many cases, the time and, consequently, the cost involved in the balancing procedure is high due to the need to accelerate the rotor up to every critical speed to be balanced in every iteration of the traditional influence coefficients method. Recently, a novel method which does not need to accelerate the rotor up to every critical speed to be balanced was proposed. In this method, active magnetic bearings are used to apply a parametric excitation at the combination resonance frequencies inducing an effect similar to transferring kinetic energy from a lower mode to higher modes. Therefore, maximizing the energy transferred is mandatory to obtain a high signal-to-noise ratio and capture the correct responses of the higher modes to successfully balance the rotor. This paper study the sensibility of the kinetic energy transfer between modes to the parameters of the parametric excitation; namely amplitude, frequency, and phase. The analyses are performed via computational simulations of a flexible rotor sustained by two AMBs and with three critical speeds in its operational range.
Analysis of synthesized non-Gaussian excitations for vibration-based fatigue life testing
Authors: Troncossi Marco , Pesaresi Emanuele 
Published: July 2019

Abstract
Certain applications require that some critical components must undergo qualification tests to check their suitability with respect to vibration excitations. Measured field data are commonly considered as reference for the synthesis of random stationary signals used as excitations for shakers. The current procedures usually generate test profiles in terms of PSD, corresponding to random processes with Gaussian probability distribution of values. Such signals may be unrealistic in representing the characteristics of the reference data if the latter are not Gaussian. The Kurtosis parameter is often used to synthetically represent the amount and the amplitude of signal peaks. Its value is 3.0 for Gaussian signals, whereas higher values hold for signals featuring high peaks, e.g. due to micro-shocks. In case of accelerated fatigue life tests, the synthesized signal must induce, in a limited duration, the same fatigue damage which the reference signal cause on the component throughout its expected lifetime. The Fatigue Damage Spectrum (FDS) is generally used to quantify the fatigue damage potential associated with the excitation. The test signal is synthesized targeting the same FDS of the reference profile. This paper presents two kurtosis-control algorithms of signal synthesis in combination with a technique able to match the prescribed FDS.
Efficient parameter identification and model selection in nonlinear dynamical systems via sparse Bayesian learning
Authors: Fuentes R. , Dervilis N. , Worden K. , Cross E.J. 
Published: July 2019

Abstract
Bayesian inference plays a central role in many of today’s system identification algorithms. However, one of its major drawbacks is that it often requires solutions to analytically intractable integrals, and this has led to solutions via Markov Chain Monte Carlo (MCMC). Today, few Bayesian system identification methods can compete with the robustness of the family of MCMC solutions. However, MCMC suffers severely from its computational cost.
Partly fuelled by the field of Compressive Sensing (CS), an interest in the machine learning community has arisen in sparse linear regression. Its value in identification of dynamical systems has also recently started to receive some attention. The idea is to represent the range of possible candidate functional forms that have generated a specific data set using a dictionary, and to then apply standard Lasso regression to select the “best” basis, with sparsity constraints. A major problem in this approach is that Lasso regression (and its derivatives) requires tuning of the regularisation parameter. In this paper, a procedure for selecting the “best basis” (and thus performing both model selection and system identification) is presented through a sparse Bayesian learning approach. Sparsity is induced via a hierarchical Gaussian prior and an approximation to the posterior distribution is sought using an iterative optimisation scheme for finding the optimal hyper-priors that govern prior and hence, the level of sparsity in the solution. The method is applied to five systems of engineering interest, which include a baseline linear system, an additive quadratic damping term, cubic stiffness (Duffing oscillator), Coulomb damping and a Bouc-Wen hysteresis model. The results are shown using numerical simulations. It is shown that this approach can identify not only the correct model parameters, but whether a nonlinearity is present in the system as well its type. With the formulation being Bayesian, it also yields estimates of uncertainty over the selected basis functions and predicted responses.
Identification of a Duffing oscillator using particle Gibbs with ancestor sampling
Authors: Rogers T J , Schön T B , Lindholm A , Worden K , Cross E J 
Published: July 2019

AbstractThe Duffing oscillator remains a key benchmark in nonlinear systems analysis and poses interesting challenges in nonlinear structural identification. The use of particle methods or sequential Monte Carlo (SMC) is becoming a more common approach for tackling these nonlinear dynamical systems, within structural dynamics and beyond. This paper demonstrates the use of a tailored SMC algorithm within a Markov Chain Monte Carlo (MCMC) scheme to allow inference over the latent states and parameters of the Duffing oscillator in a Bayesian manner. This approach to system identification offers a statistically more rigorous treatment of the problem than the common state-augmentation methods where the parameters of the model are included as additional latent states. It is shown how recent advances in particle MCMC methods, namely the particle Gibbs with ancestor sampling (PG-AS) algorithm is capable of performing efficient Bayesian inference, even in cases where little is known about the system parametersa priori. The advantage of this Bayesian approach is the quantification of uncertainty, not only in the system parameters but also in the states of the model (displacement and velocity) even in the presence of measurement noise.