bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and characterization of flexible PVDF-HFP film for piezoelectric applications
Authors: Yuennan Jureeporn , Muensit Nantakan
Published: January 2020

We report on the preparation of electroactive β-phase in polyvinylidene fluoride hexafluoropropylene (PVDF-HFP) without any electrical poling treatment. The PVDF-HFP film with various mass fractions (wt%) of magnesium chloride hexahydrate salt (MgCh∼6H2O) was fabricated by a solution casting technique. The morphological, mechanical, structural and dielectric properties were investigated. Results founded that the PVDF-HFP composite films show a large number of micro-pores on the top surface as a sponge-like structure. The Young’s modulus and crystallinity values tend to be linearly decreased with the MgCh2⋗6H2O concentration leading to enhance flexibility. The largest β-phase fraction of 87.2% is found in the composite with 1 wt% MgCh2⋗6H2O filler. The obtained value is 4 times higher than the value of unfilled PVDF-HFP. Moreover, the maximum value of dielectric constant is about 19.2 at 10 Hz for 4 wt% MgCh2⋗6H2O filler. Therefore, the modified composites with the excellent flexibility, dielectric constant and β-phase may be a promising material for applications in the field of piezoelectric energy conversion.
Advances in Precision Control of Magnetic Microrobots
Authors: Mustafa Aalim M. , Khaled Nassim
Published: January 2020

Magnetic actuated systems promise great commercial applications. For instance, it can be used to precisely control the targeted drug delivery and minimally invasive medical applications. In this paper, we have summarized recent advances in the field of control and path planning of magnetic microrobots. We have investigated the main differences between approaches, materials, trajectories, control methods and the main features of each research paper.
An Automatic Calibration Method for Puncture Surgical Robot
Authors: Yuan H X , Li Q Q , Zhao H , Wang L J , Song R
Published: January 2020

This paper proposes a rapid and automatic calibration method for puncture surgery robot, via which the hand-eye and tool calibration can be accomplished automatically in a short time. A new method for coordinate conversion between robot flange and needle tip is proposed, based on the method of spherical fitting and singular value decomposition. The experimental results show that the calibration accuracy and stability of this method can meet clinical requirements. There are good prospects for this method using in surgical calibration application.
Analytical Calculation of Large Deflection of Annular Thin Plate of Damping Valve
Authors: Chen Yijie , Nie Wei , Gao Xiaodong , Li Baoqiang , Wan Yiqiang
Published: January 2020

Aiming at the phenomenon of bending deformation caused by the pressure difference of the throttle plate in the working process of the damping valve, the analytical calculation of the large deflection of the annular thin plate was carried out. On the basis of extracting the physical model of the thin plate, the boundary conditions and initial conditions of the annular thin plate were set by using the Qian’s perturbation method, and the nonlinear large deflection deformation analytical formula was derived; Through the finite element modeling, the accurate numerical solution of thin plate deformation was obtained, and the key parameters of the analytical formula were corrected by the least squares method. Through verification, the modified analytical formula had the characteristics of easy calculation and high calculation accuracy, and the influence law of the large deflection of the throttle valve was studied, which provided the necessary theoretical support for the accurate design of the damping valve performance.
Effects of Manufacturing Tolerances on Dynamic Properties of Journal Bearings
Authors: Ma Xun , Xu Wubin , Jin Sun , Zhang Xueping , Li Bing
Published: January 2020

Dynamic properties of journal bearings were analysed when manufacturing tolerances existed. A methodology was proposed to predict journal bearing properties and to seek a relationship between the manufacturing tolerances and the dynamic coefficients. All the dynamic coefficients of journal bearings were investigated against Sommerfeld number and four types of standard tolerance grades in laminar flow regimes respectively. The results showed that manufacturing tolerances had a significant influence on the dynamic coefficients, especially the cross terms of both stiffness and damping coefficients. The more the magnitude of manufacturing tolerance grade is, the more variations of dynamic coefficients are. It is recommended to take the effect of tolerances on the dynamic performance of journal bearings on its design stage.
A 20.5 dBm Outphasing Class-F PA with Chireix Architecture at 3.5 GHz for RF Transmitter Front-end
Authors: Sun Yusheng , Du Sichun
Published: January 2020

An outphasing class-F power amplifier (PA) with Chireix architecture is presented in Global Foundry (GF) 0.13µm Complementary Metal Oxide Semiconductor (CMOS) technology. The proposed circuit is composed of two branch class-F PA and Chireix power combiner with a floating load. The designed outphasing amplifier can provide 20.5 dBm output power from 1.8 V power supply at 3.5 GHz with 52.9 % power added efficiency (PAE). Wideband Code Division Multiple Access (W-CDMA) signal is implemented as input signal to simulate ACPR and the adjacent channel leakage ratios (ACLRs) at ±5 MHz are -20.5 dBc/-20.7dBc. After DPD (Digital Pre-Distortion) ACLRs can achieve -44.5 dBc/-44.7dBc at ±5 MHz. Furthermore, the chip area including testing pads is 1.98*1.62 mm
2.
Study on Simulation of Warning Method and Evaluation of Car-following for Intelligent Drive
Authors: Nv-er Ren , Rong Jiang , Xu Cheng
Published: January 2020

Car-following behavior is one of the main driving behaviors of drivers in road traffic environment, the simulation experiment for car-following early warning of intelligent driving can provide driver with safe and efficient verification before Real Vehicle Experiments. The focus of the research is how to detect car-following distance by LiDAR and evaluate the car-following warning method under the simulation environment. In this paper, the mathematical model of LiDAR was established in the simulation environment so that we can obtain the Time Headway changing to warn driver to accelerate or not in real time. Next in importance, in Unreal Engine 4 virtual scene, by using the special collision detection box to simultaneously detect the longitudinal and lateral relative positions of the ego vehicle and the front vehicle, we can complete the comprehensive evaluation of car-following behavior in both horizontal and vertical directions. Ultimately, to verify the validity and reliability of this method, hardware-in-the-loop simulation of car-following warning method was realized by connecting the driving simulator. As a consequence, by using the method of this paper, we provide a feasible technical scheme for intelligent driving vehicles in respect of multi-lane car-following warning.
Multi-objective Excavation Trajectory Optimization for Intelligent Electric Shovel Based on ROS
Authors: Fan Zhonglei , Zhang Tianci , Qiao Jianqiang , Li Guang , Zhao Yonggang , Wang Xin , Sun Wei , Song Xueguan
Published: January 2020

Electric shovel is a large-scale excavation equipment, which often suffer from discontinuous and inefficient excavation due to complicated mine condition. To address these challenges, a multi-objective optimization strategy for electric shovel is proposed to achieve an efficient, stable and intelligent operation. Firstly, the dynamical model of the electric shovel system is established based on Lagrange method. Then, the minimum energy consumption per volume and minimum relief angle difference are regarded as the optimization formulation considering multiple system constraints. Finally, the strategy is applied to the ROS-based intelligent prototype of shovel to verify the effectiveness. The results show that the multi-objective optimization strategy of the excavation trajectory has great guiding significance for the design of the intelligent electric shovel.
Research of Load Distribution Between Working and Backup Rolls of Sheet Levelling Machine with Regard to Gaps and Heat Strain
Authors: Yu Belyaev S , Chechulin Yu B , Fedulov A A , Yu Bulganina M
Published: January 2020

The article addresses to distribution of loading between working and backup rolls of sheet levelling machines taking into account presence of initial gaps between them and heating that occurs during the straightening process, which is especially important in case of the high-temperature straightening. For levelling machines with a single row of backup rolls calculated dependencies were obtained to evaluate loads suffered by backup roll taking into account factors under this study and the analysis of results for the 9-roll straightening machine were carried out. The analysis showed a significant overload suffered by backup rolls.
The Development and Application of Methodologies for the Design of Technological Modes of Cold Rolling
Authors: Kozhevnikov A V
Published: January 2020

The article describes the methodology of designing technological modes of cold rolling of thin steel strips on continuous mills, according to which the design process is presented in the form of seven interconnected modules that perform certain functions. As a result of the implementation of the principles, effective deformation modes are obtained, which provide a reduction in total energy costs by 5-8 % in compliance with the requirements for the quality indicators of the strip.
Analysis of the Microstructure Evolution in the Implementation of a New Macro Shear Rolling Technology
Authors: Naizabekov A B , Lezhnev S N , Panin E A
Published: January 2020

In the work on the basis of computer modeling, a comparative analysis of the rolling technology of a plate billet, which includes rolling in relief rolls with subsequent rolling in rolls with a smooth barrel to the desired size, compared with the existing rolling technology was performed. The results of comparison of deformation schemes using microstructure evolution indicate the advantage of the proposed technology compared with the current rolling technology.
The Effect of Prior Comparison MRI on Interpretive Performance of Screening Breast MRI
Authors: Burk Kristine S , Edmonds Christine E , Mercaldo Sarah F , Lehman Constance D , Sippo Dorothy A
Published: January 2020

Objective

To evaluate the effect of prior comparison MRI on interpretive performance of screening breast MRI.

Methods

After institutional review board approval, all screening breast MRI examinations performed from January 2011 through December 2014 were retrospectively reviewed. Screening performance metrics were estimated and compared for exams with and without a prior comparison MRI, using logistic regression models to adjust for age and screening indication (BRCA mutation or thoracic radiation versus breast cancer history versus high-risk lesion history versus breast cancer family history).

Results

Most exams, 4509 (87%), had a prior comparison MRI (incidence round), while 661 (13%) did not (prevalence round). Abnormal interpretation rate (6% vs 20%, P < 0.01), biopsy rate (3% vs 9%, P < 0.01), and false-positive biopsy recommendation rate per 1000 exams (21 vs 71, P < 0.01) were significantly lower in the incidence rounds compared to the prevalence rounds, while specificity was significantly higher (95% vs 81%, P < 0.01). There was no difference in cancer detection rate (CDR) per 1000 exams (12 vs 20, P = 0.1), positive predictive value of biopsies performed (PPV3) (35% vs 23%, P = 0.1), or sensitivity (86% vs 76%, P = 0.4).

Conclusion

Presence of a prior comparison significantly improves incidence round screening breast MRI examination performance compared with prevalence round screening. Consideration should be given to updating the BI-RADS breast MRI screening benchmarks and auditing prevalence and incidence round examinations separately.
An Interprofessional End-of-Life Simulation to Improve Knowledge and Attitudes of End-of-Life Care Among Nursing and Physical Therapy Students
Authors: Campbell Denise , Trojanowski Suzanne , Smith Leslie M.
Published: January 2020

Background:

Preprofessional end-of-life (EOL) education may be inadequate, leaving a gap in students' knowledge and understanding to manage a dying patient. Attitudes toward a dying patient can affect the quality of care being provided. Simulation-based learning experience (SBLE) can assist with handling emotional situations such as EOL care.

Purpose:

The purpose of this project was to describe an interprofessional education (IPE) EOL SBLE to evaluate the changes in students' knowledge and attitudes in EOL care.

Methods:

A quasi-experimental repeated-measures pre/posttest design was used to evaluate attitudes, awareness, and behaviors of students during a simulated EOL experience. Eighty-three nursing and physical therapist students participated in an SBLE focusing on EOL care. The Frommelt Attitudes Toward Care of the Dying Scale—Form B (FATCOD-B) was completed pre/post-SBLE. Students completed a written reflection of their experience and role within the SBLE.

Results:

The results from the FATCOD-B showed significant improvement. A 2-tailed P value (P = .0003) showed post-SBLE mean score being 4.02, demonstrating a significant improvement on the scores from pre- to post-SBLE. Qualitative data from the students' reflections demonstrated a positive response to the SBLE. Students commented the SBLE prepared them to care for a dying patient and working collaboratively with students from another discipline reinforced teamwork.

Conclusion:

There is significant evidence demonstrating the unpreparedness of health care professionals in caring for the dying patient. The results of this project demonstrated that incorporating an EOL simulation into curricula improved students' knowledge, skills, and attitudes toward patients and their family members at EOL.
Design and Implementation of the Health Professions Simulation Assessment, a Tool to Assess Students' Perceptions of Simulation Experiences
Authors: Greenwood Kristin Curry , Kirwin Jennifer , Huo Zhiguang
Published: January 2020

Background:

Simulation is an important educational method in the health professions. While several academic programs have shared simulation quality assessment tools that are intended to be used in a particular discipline, a valid and reliable assessment that can be used by a variety of entry-level health professions education programs is lacking. In order to improve and refine interprofessional simulation programs, a tool that is acceptable to the multiple professions that participate in interprofessional simulation education is needed. The purpose of this study was to design and analyze an evidence-based quality assessment tool that could capture students' perceptions of simulation experiences and could be used by multiple health professions.

Subjects:

The study included 329 students from different health professions majors who participated as part of their required coursework.

Methods:

An evidence-based Health Professions Simulation Assessment (HPSA) was created in 2016, pilot tested in 2017, and then disseminated to a larger cohort in 2018. The results of the second dissemination were analyzed using R software to understand the validity and utility of the tool.

Results:

The response rate for each question was more than 90% and the mean rate of agreement was 79.0% (±8.9%). We observed a high correlation among all pairs of questions (mean 0.51, SD 0.19). In addition, we performed hierarchical clustering and identified 4 clusters of questions that were highly correlated (preparation for experience, self-reflection/emotions, debriefing, and fidelity).

Conclusion:

An evidence-based tool was created that could be used in a variety of health professions programs to evaluate students' perceptions of the quality of a simulation. This easily administered tool demonstrated satisfactory agreement; the data gathered through its use may be used to improve the quality of simulations in entry-level health professions education programs. This tool was found to be acceptable to multiple professions and could be used in interprofessional student groups to obtain a shared assessment of a simulation. Further research is warranted to determine validity among interprofessional groups of students.
Recurrent Pancreatitis in Children
Authors: Ellery Kate M. , Uc Aliye
Published: January 2020

Recurrent acute and chronic pancreatitis are increasingly recognized in childhood. Etiologies are vastly different in children compared with adults and mostly involve genetic and anatomical factors with negligible contribution of environmental risks. Pediatric acute recurrent pancreatitis (ARP) and chronic pancreatitis (CP) have significant impact on quality of life with high healthcare costs. Children with these conditions suffer from recurrent acute or chronic abdominal pain and they endure multiple emergency room visits, hospitalizations, procedures, and surgeries. Diagnostic methods are being developed; treatment options are limited. This review summarizes the most recent developments in pediatric ARP and CP. These discoveries will help physicians provide optimal care for children with these conditions.
EZcalcium: Open Source Toolbox for Analysis of Calcium Imaging Data
Authors: Cantu Daniel A. , Wang Bo , Gongwer Michael W. , He Cynthia X. , Goel Anubhuti , Suresh Anand , Kourdougli Nazim , Arroyo Erica D. , Zeiger William , Portera-Cailliau Carlos
Published: January 2020

Fluorescence calcium imaging using a range of microscopy approaches, such as 2-photon excitation or head-mounted ‘miniscopes’, is one of the preferred methods to record neuronal activity and glial signals in various experimental settings, including acute brain slices, brain organoids, and behaving animals. Because changes in the fluorescence intensity of genetically encoded or chemical calcium indicators correlate with action potential firing in neurons, data analysis is based on inferring such spiking from changes in pixel intensity values across time within different regions of interest. However, the algorithms necessary to extract biologically relevant information from these fluorescent signals are complex and require significant expertise in programming to develop robust analysis pipelines. For decades, the only way to perform these analyses was for individual laboratories to write their own custom code. These routines were typically not well annotated and lacked intuitive graphical user interfaces (GUIs), which made it difficult for scientists in other laboratories to adopt them. Although the panorama is changing with recent tools likeCaImAn,Suite2Pand others, there is still a barrier for many laboratories to adopt these packages, especially for potential users without sophisticated programming skills. As 2-photon microscopes are becoming increasingly affordable, the bottleneck is no longer the hardware, but the software used to analyze the calcium data in an optimal manner and consistently across different groups. We addressed this unmet need by incorporating recent software solutions for motion correction, segmentation, signal extraction and deconvolution of calcium imaging data into an open-source, easy to use, GUI-based, intuitive and automated data analysis software, which we namedEZcalcium.
Tramadol as a pain relieving and physical work performance enhancement medication
Authors: Madukwe Ann Ukachi , Klein Axel
Published: January 2020

Purpose

The purpose of this paper is to assess participants’ perception that tramadol enhances physical work performance and acts as a pain relief.

Design/methodology/approach

The participants were 30 (18 male and 12 female) tramadol-using emerging adults, aged 16–27 years, selected through respondent-driven sampling. The majority of the participants were university students, whereas others had completed senior secondary education. The study adopted a qualitative design. Qualitative data were analysed using thematic analyses.

Findings

In general, respondents perceived and used tramadol for pain relief and physical work performance enhancement. The result showed that sex, employment status and daily dosage were not associated with respondents’ perception of tramadol as a pain-relieving medication. In contrast, sex and employment status were associated with participants’ perception of tramadol as a physical work performance enhancement medication, but daily dosage was not.

Research limitations/implications

Some users refused to participate because they were afraid of being exposed to law enforcement.

Practical implications

Male and female emerging adults are involved in non-medical use of tramadol. Prevention and intervention programs to reduce or stop this behaviour are needed, especially in the rural communities.

Social implications

The result showed that users were mostly from poor homes, whose parents could not afford university education and who were not qualified to get good government paying jobs. So, the use of tramadol became necessary for them to make more money from the kind of jobs they did. Reduction of the cost of university education and provision of regular jobs for this population are some of the measures recommended to counter non-medical use of tramadol by this population.

Originality/value

This is the first study in South-eastern Nigeria that focused on the non-medical use of tramadol among emerging adults, using a qualitative design.
The role of spatial intelligence in predicting web information searching behavior and performance of high school students
Authors: Naghib Fatemeh , Mirzabeigi Mahdieh , Alborzi Mahboobeh
Published: January 2020

Purpose

The purpose of this paper is to identify the role of spatial intelligence in predicting the web information searching behavior and performance of high school students.

Design/methodology/approach

The population of this study consisted of all female students who were studying in the eighth and ninth grades of Shiraz University School. The students searched an educational website by using keywords to find some answers to two tasks (one simple task and one complex task).

Findings

The findings of this study revealed that among the five components of spatial intelligence, the three components of spatial orientation, perceptual speed and flexibility of closure could better predict the web searching behavior and performance of the students. To elaborate, spatial orientation could predict the query length and the search time; perceptual speed was helpful in predicting the reformulation of the question, the number of results pages observed, the number of links viewed, and success; flexibility of closure also predicted the success in the search.

Originality/value

The results of this study can help researchers and others understand the searching behavior and performance of children and the cognitive factors which affect them. The results can also help teachers and school librarians to teach students the necessary skills and design interactive systems that take into account adolescents’ different cognitive approaches. While other studies have focused on adults’ and university students’ behavior, this study examined the adolescents’ behavior. Furthermore, although the previous studies have attempted to investigate just one dimension of the searching process, i.e., either behavior or performance, this study simultaneously focused on both dimensions and examined both searching behavior and performance through keyword searching strategy.
Constraining invader dominance: Effects of repeated herbicidal management and environmental factors on curlyleaf pondweed dynamics in 50 Minnesota lakes
Authors: Verhoeven Michael R. , Larkin Daniel J. , Newman Raymond M.
Published: January 2020

Curlyleaf pondweed (Potamogeton crispus) is one of the most widespread and widely managed aquatic invasive plants in North America. Despite decades of management, the efficacy of long‐term management strategies and the effects of environmental drivers on curlyleaf pondweed populations remain uncertain.

To evaluate the effects of management and environmental factors on within‐lake distribution and local density of curlyleaf pondweed, we collated monitoring data from point–intercept surveys collected by a variety of lake managers across Minnesota, U.S.A. Using this dataset, comprising 177 lake‐years of plant data, we examined the influence of herbicide treatment, water clarity, snow depth, and ice cover duration on curlyleaf pondweed distribution and density between 2006 and 2015.

We evaluated the effects of herbicides on curlyleaf pondweed at three time points relative to treatment: within year, carryover effects the following year, and cumulative effects over multiple years of treatment. All three temporal measures were associated with significant reductions of curlyleaf pondweed. Additionally, herbicidal management reduced both the density and distribution of curlyleaf pondweed. Given that herbicide management led to reductions that carried over into future years, managers may be able to design multi‐year treatments to reduce total management effort over time.

We also found strong effects of environmental conditions on curlyleaf pondweed. Elevated lake productivity and decreased winter snow cover were associated with increased springtime distributions of curlyleaf pondweed, whereas duration of winter ice cover had no influence. The influence of productivity suggests that reductions of this invasive species may be an ancillary benefit of water‐quality improvements that lower lakes’ trophic status. Our results also show that decreased winter snow cover, as predicted under climate change, could exacerbate problematic growth of curlyleaf pondweed.

Harnessing monitoring data from multiple projects, as this study does, allows for robust inference about environmental and management constraints on macrophytes. Because of environmental and management variability, we suggest that treatment regimens follow an adaptive management cycle, with outcomes of management monitored and evaluated, and strategies updated accordingly. It is also vital to continue monitoring both managed and unmanaged lakes to enable stronger inferences about treatment effectiveness.
State and societal responses to natural disasters in Latin American and Caribbean history
Authors: Dauer Quinn P.
Published: January 2020

Natural hazards—earthquakes, hurricanes, floods, droughts, volcanoes, famines, epidemics, and climatic events such as El Niño–Southern Oscillations—have repeatedly struck Latin America and the Caribbean since pre‐Columbian times. The natural disasters that result provide historians an optic into political, social, economic, and cultural structures under stress and stripped of their everyday façades during the colonial and modern periods. Catastrophes reveal the ability of governments and administrators to efficiently and adequately respond, highlight embedded mentalities and social relationships, contribute to political and economic transformations, underscore scientific and technological advances, and the persistence of religious perspectives of calamities. States and societies that repeatedly experience natural hazards develop a culture of disaster to adapt and cope with catastrophic events by creating institutions and building codes, architecture, and mentalities. A historical perspective of contemporary calamities examines the political decisions, social and economic structures, and cultural milieu over time that created the natural disasters.
Development of LTCC micro‐hotplate with PTC temperature sensor for gas‐sensing applications
Authors: Kulhari Lokesh , Ray Kanad , Paptan Ankit , Suri Nikhil , Khanna Pramod K
Published: January 2020

Low temperature co‐fired ceramic (LTCC) micro‐hotplates show wide applications in gas sensors and micro‐fluidic devices. It is easily structured in three‐dimensional structures. This paper presents the low power consumption micro‐hotplates which were developed with PTC (positive temperature coefficient) temperature sensor and inter‐digitated electrodes. The paper presents two different structures for micro‐hotplate with platinum as a heating element. The PTC temperature sensor using two different materials viz. PdAg and platinum paste are developed with micro‐hotplates. The simulation has been achieved through COMSOL for LTCC and alumina micro‐hotplates. The temperature variation with power consumption has been measured for the developed LTCC micro‐hotplates. The change in resistance of PTC temperature sensors was measured with micro‐hotplate temperature. The aim of this study was to place a temperature sensor with the gas sensor module to measure and control the temperature of micro‐hotplate. A SnO2 sensing layer is coated on LTCC micro‐hotplate using screen printing and characterized for the sensing of carbon monoxide gas (CO). This study will be beneficial for designing hotplates based on LTCC technology with low power consumption and better stability of temperature for gas‐sensing applications.
Withstanding Pressure in Any Shape
Authors: Gonzalez Carlos M. , Borge Richard
Published: January 2020

A pressure vessel that features an internal lattice structure, which allows the vessel to be constructed to any size or shape.
Multiple-Benefit Analysis of Scaling-Up Building Energy Efficiency Programs: The Case Study of Tunisia
Authors: Krarti Moncef
Published: January 2020

This paper evaluates the benefits of scaling-up energy efficiency and renewable energy programs for the building sector in Tunisia. Both energy and non-energy benefits are quantified using a bottom-up analysis approach to assess economic, environmental, and social impacts of a wide range of energy policies targeting new and existing Tunisian building stocks. The investments required to scale-up programs set to improve the energy efficiency performance of existing building stocks are determined in order to assess both their cost-effectiveness and their impact on the overall energy productivity of Tunisia's economy. The energy productivity analysis is performed to account for both energy and non-energy benefits of building-integrated energy efficiency programs. The energy productivity analysis clearly shows that retrofitting existing building stock has several benefits for Tunisia including reduction of the national energy consumption as well as improvement of the country's overall economy energy efficiency. However, only basic retrofit programs are found to be cost-effective for the private sector to implement with discounted payback periods of less than 5 years. Combined with improving the energy efficiency of new and existing buildings, the installation of rooftop photovoltaic systems for households can significantly lower reliance of Tunisia on imported fuels and improve the energy productivity of its overall economy.
Effect of Ankle Angles on the Soleus H-Reflex Excitability During Standing
Authors: Dutt-Mazumder Aviroop , Segal Richard L. , Thompson Aiko K.
Published: January 2020

This study investigated effects of ankle joint angle on the Hoffman’s reflex (H-reflex) excitability during loaded (weight borne with both legs) and unloaded (full body weight borne with the contralateral leg) standing in people without neurological injuries. Soleus H-reflex/M-wave recruitment curves were examined during upright standing on three different slopes that imposed plantar flexion (−15°), dorsiflexion (+15°), and neutral (0°) angles at the ankle, with the test leg loaded and unloaded. With the leg loaded and unloaded, maximum H-reflex/maximum M-wave ratio of −15° was significantly larger than those of 0° and +15° conditions. The maximum H-reflex/maximum M-wave ratios were 51%, 43%, and 41% with loaded and 56%, 46%, and 44% with unloaded for −15°, 0°, and +15° slope conditions, respectively. Thus, limb loading/unloading had limited impact on the extent of influence that ankle angles exert on the H-reflex excitability. This suggests that task-dependent central nervous system control of reflex excitability may regulate the influence of sensory input on the spinal reflex during standing.
Congress again rejects Trump cuts, smiles on science agencies
Authors: Mervis Jeffrey
Published: January 2020

2020 spending bill increases research budgets, but next year will be tougher as lawmakers will have less to spend.
Electrostatics affect the glow
Authors: Hu Cheng , Liu Xiaohong , Wang Jiangyun
Published: January 2020

Chromophore twisting is probed with unnatural amino acids
Chronic Infections by Herpes Simplex Viruses and by the Horse and Cat Herpesviruses
Authors: Plummer G. , Hollingsworth D. C. , Phuangsab A. , Bowling C. P.
Published: January 2020

Rabbit eyes experimentally infected with either type 1 or type 2 herpes simplex viruses occasionally released virus spontaneously. Injection of adrenalin was not highly effective for stimulating virus release but did seem to have a slight and erratic activating capacity. No spontaneous virus release were detected from the eyes of six cats infected with cat herpesvirus, but, when adrenalin was administered, an episode of virus release did ensue in one animal. Rabbit spinal cords could be chronically infected with either herpes simplex virus type 2 or equine herpesvirus type 2. The viruses could be reisolated over subsequent months from about half the animals without prior stimulation; the interval between inoculation of trypsinized spinal tissue into tissue cultures and the development of cytopathic effect was often long—more than 4 weeks in some cases.
Solubilization and Characterization of a Protective Antigen of
Erysipelothrix rhusiopathiae
Authors: White R. R. , Verwey W. F.
Published: January 2020

A particulate fraction of
Erysipelothrix rhusiopathiae
cultures has been subjected to butanol extraction and treatment with surface-active agents in an attempt to solubilize a protective antigen. The particulate fraction was partitioned into the butanol layer but was not solubilized. Only sodium dodecyl sulfate solubilized the particles. The soluble protective activity was not sedimented by centrifugation at 198,000 ×
g
for 12 hr but was excluded by Sephadex G-200. Immunodiffusion studies of the soluble fraction demonstrated eight antigens, five of horse serum origin and three of
E. rhusiopathiae
origin. Ultracentrifugation indicated that spontaneous reaggregation occurred after removal of the sodium dodecyl sulfate. Analytical ultracentrifugation showed that 90% of the sodium dodecyl sulfatetreated material migrated as a single homogeneous 3.5
S
component. The physical and biological characteristics of the protective activity suggest that the protective antigen is a glyco-lipoprotein.
Interaction of Staphylococcal Enterotoxin B with Cell Cultures I. Effect of Serum and Testing Procedures
Authors: Schaeffer Warren I.
Published: January 2020

The cytopathic effect of staphylococcal enterotoxin B upon mammalian cell cultures is expressed fully only if the cultures are grown in human serum-supplemented media. Little cytotoxicity is seen if the cells are grown in horse serum-supplemented media and none is seen if the cells are grown in calf serum-supplemented media. The cytotoxicity of the toxin is reversible at any stage of intoxication. Cytotoxicity is rarely seen before 5 hr and is most often not evident before 8 hr. Cytoxicity is not lethal.
Antitoxic Immunity in Experimental Cholera: Observations with Purified Antigens and the Ligated Ileal Loop Model
Authors: Finkelstein Richard A.
Published: January 2020

Rabbits immunized with purified antigens, choleragen and choleragenoid (cholera exo-enterotoxin and natural toxoid), were found to resist intra-intestinal challenge with a variety of strains of cholera vibrios. The resistance occurred in the absence of a significant antibacterial antibody response. In fact, the antigens were incapable of protecting mice against the septicemic infection of the standard mouse protection test used for bioassay of conventional cholera vaccines. The immunized rabbits did, however, develop a significant antitoxin titer demonstrable by passive hemagglutination, although the presence of antitoxic coproantibody could not be established conclusively. The results suggest the potential value of antitoxic immunity in cholera and are consistent with the existence of only one serological type of cholera exo-enterotoxin.
Effect of Bactericidal Substance from
Staphylococcus aureus
on Group A Streptococci I. Biochemical Alterations
Authors: Dajani Adnan S. , Gray Ernest D. , Wannamaker Lewis W.
Published: January 2020

A bactericidal substance isolated from phage type 71 staphylococci has been studied relative to its mechanism of action on streptococcal cells. The substance exerts its effect best at 37 C. No cell lysis occurs as evidenced by lack of alteration in optical density of susceptible cell suspensions. The bactericidal substance results in immediate cessation of protein and deoxyribonucleic acid synthesis as well as degradation of newly and previously formed ribonucleic acid (RNA). The action on RNA seems to be independent of protein synthesis.
Electron Microscopy of Cell Cultures Infected with a Chlamydial Agent Causing Polyarthritis of Lambs
Authors: Cutlip Randall C.
Published: January 2020

McCoy cell cultures infected with the agent of ovine chlamydial polyarthritis were examined with the electron microscope. The agent was seen as small dense particles (250 to 450 nm) with an eccentric nucleoid and a multilaminated cell wall, as large (800 to 1,200 nm) granular particles surrounded by two unit membranes and as intermediate particles. Replication, which occurred throughout the cytoplasm, was initiated by phagocytosis of a small dense particle and terminated by rupture of the plasma membrane. Upon entering a cell, the small dense particles developed into large granular particles which divided by binary fission. Daughter particles either repeated the division or condensed to form new small dense particles.
Pyelonephritis XI. Effect of Growth Phase of
Streptococcus faecalis
on Serum Susceptibility and Virulence
Authors: Guze Lucien B. , Hubert Earl G. , Kalmanson George M.
Published: January 2020

Rapidly growing
Streptococcus faecalis
was found to be markedly susceptible to the bactericidal activity of normal rat and rabbit sera, whereas stationary-phase organisms were resistant. In contrast, human serum killed neither phase organism. Further, human serum was found to interfere with killing by rabbit serum. The serosusceptible, rapidly growing organisms were less virulent than the seroresistant, stationary-phase organisms. This was tested by production of pyelonephritis in the rat after intravenous inoculation of the organism. Renal bacterial content over a period of 4 weeks was significantly less in those animals which had received rapidly growing organisms.
Effect to tween 80 and aquasol A on virus plaque formation
Authors: Blalock J E , Tullish J , Gifford G E
Published: January 2020

The enhancement of vesicular stomatitis virus plaques on human embryonic lung cells in the presence of Tween 80 or Aquasol A was studied to determine the optimal conditions for the enhancement. Enhanced numbers and sizes of vesicular stomatitis virus plaques occurred when Aquasol A or Tween 80 was added to the cell culture 30 min before virus adsorption but not when added after adsorption. These substances did not have a direct effect on the virus and did not have an effect on virus adsorption or penetration. A few other viruses and cell systems were also studied to determine if enhancement would extend to other viruses and cell systems. The cell system seemed to be important since enhancement of vesicular stomatitis virus plating efficiency did not occur on chicken embryo cells. However, the virus was also important since vaccinia virus plating efficiency was not enhanced on the human embryonic lung cell. The greatest enhancement encountered was the increase in the plating efficiency of Friend leukemia virus on S+L- cells.
Response to primary infection with Herpesvirus saimiri in immunosuppressed juvenile and newborn squirrel monkeys
Authors: Martin L N , Allen W P
Published: January 2020

Immunosuppression of juvenile squirrel monkeys with combined azathioprine, prednisolone, and antilymphocyte globulin resulted in decreased antibody responses to viral antigens after primary infection with Herpesvirus saimiri (HVS). The virus was repeatedly isolated from the oropharynx of immunosuppressed monkeys but not from untreated infected controls. Thus immune factors are important in inhibiting shedding of HVS from the oropharynx. HVS could be isolated from the peripheral blood lymphocytes of infected control monkeys but not from the lymphocytes of immunosuppressed monkeys. Immunosuppressed monkeys also had decreased percentages of lymphocytes capable of forming rosettes with sheep erythrocytes. These results indicate that the immunosuppressive agents had inhibitory effects on lymphocytes (presumably thymus derived) capable of being latently infected with HVS. Antibody responses in newborn monkeys infected with HVS were delayed compared with juvenile monkeys. Treatment of newborn monkeys with antilymphocyte globulin had no suppressive effect on antibody responses to HVS.
Cell-mediated immunity in guinea pigs to subunits derived from hepatitis B surface antigen
Authors: Cabral G A , Chairez R , Marciano-Cabral F , Suarez M , Dreesman G R , Melnick J L , Hollinger F B
Published: January 2020

Guinea pigs immunized wit- hepatitis B surface antigen (HBSAg), types adw and ayw, and with two polypeptides (400,000 and 24,000 molecular weight) developed cell-mediated immunity (CMI), as determined by radioimmunoassay. Peritoneal exudate (PE) cells from guinea pigs immunized with the 40,000-molecular-weight polypeptide migrated poorly (30 to 88% inhibition) after challenge with the immunizing subunit or with purified HBSAg, type gdw or ayw. Response of the same PE cells to the 24,000-molecular-weight subunit was significantly reduced. Similar but less striking evidence for CMI was observed was PE cells derived from guinea pigs inoculated with purified type-specific HBSAg or with the 24,000-molecular-weight polypeptide. Humoral responses were predictable and showed a reasonable degree of correlation with the CMI response. PE cells from control animals inoculated with normal human serum or polyacrylamide gel were not inhibited after challenge with purified preparations of HBSAg or with the 400,000-molecular-weight polypeptide, but did show CMI with their respective immunogens. In addition, PE cells from guinea pigs inoculated with normal human serum were inhibited from migrating after challenge with the 24,000-molecular-weight subunit, suggesting that the latter may contain an antigenic determinant related to a human serum protein.
Klebsiella pneumoniae and Staphylococcus aureus infection in mice: difference in uremia and ammoniagenesis
Authors: Walker R I , Chesbro W
Published: January 2020

Lethal infections by Staphylococcus aureus and Klebsiella pneumoniae were compared for kidney-related effects in mice. K. pneumoniae caused uremia and an increase in blood ammonia that could reach 2.5 times normal. These events did not occur in mice inoculated with S. aureus. Use of germfree animals indicated that most of the increase in ammonia arose from the gut, presumably due to greater availability of urea and ureolysis. Injected ornithine restored blood ammonia to nearly normal levels and extended survival.
Interaction of cholera enterotoxin with cultured adrenal tumor cells
Authors: Wishnow R M , Lifrak E , Chen C
Published: January 2020

In the adrenal tumor cell system ganglioside Gm1 inhibited cholera enterotoxin (CT)-induced steroidogenesis if it was preincubated with the toxin or added to adrenal cells 10 min before CT. In the preincubation studies a molar ratio of Gm1 to toxin of 3:1 was necessary for half-maximal inhibition of steroidogenesis. On the other hand, horse serum anticholeragenoid neutralized the steroidogenic response to cell-bound CT by 50% if it was added to adrenal monolayer cultures 15 min after the toxin. Specific antiserum was able to neutralized 20% of the toxin-induced activity even if it was added to adrenal cultures 2 h after CT. Phase contrast microscopy demonstrated that partial neutralization of the biochemical effect of CT by horse serum anticholeragenoid was accompanied by partial prevention of toxin-induced rounding of adrenal cells. Further studies showed that pretreatment of cultured adrenal cells with a maximal dose of CT increased cyclic adenosine 3'-5'-monophosphate formation in response to a maximal stimulating dose of adrenocorticotropin. This result suggested potentiation of hormonal activation of adenylate cyclase in intact adrenal tumor cells in response to CT.
Pathogenicity of an attenuated, temperature-sensitive mutant of western equine encephalitis virus induced by a chemical mutagen
Authors: Takayama N , Nakano M
Published: January 2020

To know the pathogenicity of the chemically induced, temperature-sensitive (ts) mutant of western equine encephalitis virus, designated tsNG39, the lethality for mice injected with tsNG39, virus yield, interferon production, and histological changes in the brains of these mice were examined in parallel with those of mice inoculated with the parent strain (PS). All of the mice injected intracranially with PS died within 3.5 days after injection irrespective of the inoculum size of virus, whereas the lethality of the mice inoculated with tsNG39 varied from 94.3 to 65.5% among groups of mice and this variation seemed to be correlated with the inoculum size of virus rather than with the maximum virus titer in the brain. By histological examination, two types of changes in the brain were distinguished, inflammatory and degenerative ones. Inflammatory changes were more prominent in the brains injected with tsNG39 than in those receiving PS. Degenerative changes were dominant in the brains injected with PS, but they were slight in the earlier phase of infection by tsNG39 became prominent only later. The degree of degenerative change was well correlated with both the virus titer in the mouse brain and the death pattern of mice injected with PS or tsNG39. Since degenerative changes are thought to be caused by the direct effect of injected virus, these results indicated that the factor responsible for the low virulence of tsNG39 was the slow viral growth in the brain.
Effect of glucocorticosteroids on phagosome-lysosome interaction
Authors: Furth R V , Jones T C
Published: January 2020

The effects of hydrocortisone on fusion of thorotrast-labeled lysosomes with phagosomes containing killed toxoplasmas was studied. Mouse peritoneal macrophages from glucocorticosteroid-treated animals fromed phagolysosomes just as effectively as macrophages from untreated animals (72% thorotrast-positive vacuoles in hydrocortisone-treated animals; 78% in controls). The electron microscopic appearence of macrophages from treated or untreated animals was similar. This observation complements studies which show no change in intracellular microbicidal activity in macrophages treated with glucocorticosteriods.