Simultaneous Access Research Articles

Building shared information infrastructure for chemical alternatives assessment

The substitution of hazardous substances with safer alternatives is being driven by policy pressures and business demands. As a result, scientific techniques for chemical alternatives assessment (CAA) have been established and communities of practice are emerging. Interest in safer chemical substitution is widely shared throughout a range of stakeholder groups across science, industry, public policy, and advocacy. Yet there is an unmet need for intentionally designed public information infrastructure to support the highly knowledge-intensive nature of CAA. We report here on the process of developing the Chemical Hazard Data Commons, an experimental project intended to support a diverse community of practitioners by providing publicly accessible chemical hazard data and tools for understanding it. In an arena where market forces and regulatory regimes have largely failed to generate the necessary knowledge, this project represents a novel application of a commons-based approach emphasizing building shared intellectual and technical capacity for CAA. The Data Commons—now a part of the related Pharos Project—includes an online portal providing simultaneous access to many different sources of information and enabling effective interactions with it. Foremost among these interactions are search and retrieval of hazard information about chemical substances, uniform display of the most relevant information, and the ability to automatically screen substances against consistent and transparent hazard-based criteria. We describe the motivation for the project and report on the principles and key considerations that guided its design as a participatory information infrastructure. We present our approach to organizing chemical information; the process of community engagement and planning; and how we constructed the system to provide functional tools. We discuss the outcomes of the project and highlight important challenges—such as fostering active participation and planning for long-term governance. With this article, we hope to inform future efforts for the collaborative development of knowledge resources for chemical alternatives assessment.

An efficient authentication and key agreement protocol for a group of vehicles devices in 5G cellular networks

In recent years, the world of wireless telecommunications is in full progress. Indeed, although the evolution of 4G mobile networks continues, the standardization work of the 5G networks is in full progress. The connected vehicle is part of the services expected from 5G. Indeed, the interconnection between vehicles promises a safer and more enjoyable driving experience. However, as the huge number of vehicle devices are increasing day by day and each vehicle must perform a full authentication procedure to reach to the network, network congestion may occur when a group of vehicles requires simultaneous access, moreover this can have a decisive effect on the promised high rate of 5G. The EPS-AKA authentication mechanism used in 4G networks is too insufficient to handle a large number of mobile devices. In this context, our article aims to define a reliable solution for the authentication of a group of vehicles simultaneous in 5G cellular networks. A reauthentication procedure is also proposed. Analysis results obtained using the SPAN tool has proven that authentication and privacy objectives are met. In addition, elaborate performance evaluations in terms of communication signalling and computational overhead demonstrate that our protocol is more efficient than those existing protocols.

Et3SiH + KO t Bu provide multiple reactive intermediates that compete in the reactions and rearrangements of benzylnitriles and indolenines.

The combination of potassium tert-butoxide and triethylsilane is unusual because it generates multiple different types of reactive intermediates simultaneously that provide access to (i) silyl radical reactions, (ii) hydrogen atom transfer reactions to closed shell molecules and to radicals, (iii) electron transfer reductions and (iv) hydride ion chemistry, giving scope for unprecedented outcomes. Until now, reactions with this reagent pair have generally been explained by reference to one of the intermediates, but we now highlight the interplay and competition between them.

Service and Resource Aware Flow Management Scheme for an SDN-Based Smart Digital Campus Environment

Recently, campuses have been embracing smart digital technologies in order to boost the efficiency of education and creativity. Thus, massive heterogeneous flows are generated as a result of multitude simultaneous access from several heterogeneous devices. This is putting pressure on campuses to make better management of their constrained resources and to ensure the required Quality of Service (QoS). In this paper, we propose a multi-flow management scheme over a software-defined smart digital campus network, named Service and Resource Aware Flow Management (SRAFM). Our approach offers a unified fully-programmable architecture, a distributed end-host-based flow characterization plane, and a centralized software-defined optimization model to efficiently manage heterogeneous flows. Network functionalities, including QoS aware routing and resource allocation optimization, are formulated as a mixed-integer linear programming problem. Due to its NP-hard complexity, we propose an approximation algorithm in a decomposed fashion based on Lagrangian Dual Decomposition (LDD) and subgradient methods to find an optimal solution for flow management. We evaluate our scheme from different aspects, including the number of simultaneous heterogeneous flows, QoS provisioning, characterization impacts, and network scalability. Compared to the well-known benchmarks in QoS aware routing and optimization problem, SWAY and LARAC, our simulation results conducted with a large number of flows over a small-scale network show promising performance. The proposed scheme significantly improves the cost reduction by 51% as compared to LARAC, the end-to-end delay by 21% and 34%, the bandwidth availability by 27% and 36%, and the QoS violation by 11% and 29% as compared to SWAY and LARAC, respectively.

Combined micro X-ray absorption and fluorescence spectroscopy to map phases of complex systems: the case of sphalerite

Combining micro-X-ray absorption spectroscopy (μXAS) and micro-X-ray fluorescence spectroscopy (μXRF) is a promising approach for the investigation of complex multi-phase systems. In this work, we have employed this approach to investigate natural sphalerite, the most common form of Zinc Sulfide. Spatially resolved elemental distribution maps of common 3d metal atoms (Zn, Cu, Ni, Co, and Fe) are superimposed with chemical speciation and structural parameter maps in order to understand the sphaleriteore-formation process and metamorphosis. Chemical speciation and structural parameters have been obtained by analyzing the μXAS spectra collected in several representative points of the sample, after μXRF mapping. In the present case, this X-ray based approach has permitted to determine the spatial distribution of the Zn species in sphalerite. The presence of two main zincite and smithsonite inclusions has been established, with the latter located close to copper impurity center. Since copper is known to remarkably reduce the corrosion resistance of zinc, resulting in the formation of carbonate as the corrosion product, this implies a possible role of Cu in the growth of the carbonate inclusions. The results obtained highlight the efficiency of this method in univocally identifying the spatial distribution of phases in complex systems, thanks to the simultaneous access to complementary information.

Problem-oriented information analytical system development for management, planningand mining enterprise production activities optimization

The paper considers the scenario analysis tool in the form initial scenarios set simulation and optimal option selection enterprise development on the basis information analytical system – integrated planning system (IPS) is considered. The IPS practical application field as a tool of simulation modeling for optimization the enterprise activity in terms the main technical and economic indicators, strategic planning and production system development, valuation and structuring assets is shown. Such tasks in the IPS framework will improve the plan recosting speed and planning accuracy, model multiple enterprise development scenarios, taking into account changes in macroeconomic indicators and solve the task choosing the optimal one, which will significantly affect the quality and speed of management decisions. This system will allow data consolidation and integration with other information and industrial enterprise analytical systems. The IPS contains applications for creating and viewing reports, as well as data preparation and analysis functionality, tools for developing and editing program code, analytical solutions for studying data structure and building analytical models, including scenario models, and is a complete analytical platform that provides a secure multi-user environment for simultaneous access to data. The system provides a specialized data warehouse section, the logical and physical structure which is designed to create a special report or a group reports for a specific section the subject area.

Power Efficient Random Access for Massive NB-IoT Connectivity.

Sensors enabled Internet of things (IoT) has become an integral part of the modern, digital and connected ecosystem. Narrowband IoT (NB-IoT) technology is one of its economical versions preferable when low power and resource limited sensors based applications are considered. One of the major characteristics of NB-IoT technology is its offer of reliable coverage enhancement (CE) which is achieved by repeating the transmission of signals. This repeated transmission of the same signal challenges power saving in low complexity NB-IoT devices. Additionally, the NB-IoT devices are expected to suffer from congestion due to simultaneous random access procedures (RAPs) from an enormous number of devices. Multiple RAP reattempts would further reduce the power saving in NB-IoT devices. We propose a novel power efficient RAP (PE-RAP) for reducing power consumption of NB-IoT devices in a highly congested environment. The existing RAP do not differentiate the failures due to poor channel conditions or due to collision. After the RAP failure either due to collision or poor channel, the devices can apply power ramping or can transit to a higher CE level with higher repetition configuration. In the proposed PE-RAP, the NB-IoT devices can re-ascertain the channel conditions after an RAP attempt failure such that the impediments due to poor channel are reduced. The power increments and repetition enhancements are applied only when necessary. We probabilistically obtain the chances of RAP reattempts. Subsequently, we evaluate the average power consumption by devices in different CE levels for different repetition configurations. We validate our analysis by simulation studies.

Normal and Easy

Work is being digitized across all sectors, and digital account sharing has become common in the workplace. In this paper, we conduct a qualitative and quantitative study of digital account sharing practices in the workplace. Across two surveys, we examine the sharing process at work, probing what accounts people share, how and why they share those accounts, and identifying the major challenges people face in sharing accounts. Our results demonstrate that account sharing in the modern workplace serves as a norm rather than a simple workaround; centralizing collaborative activity and reducing boundary management effort are key motivations for sharing. But people still struggle with a lack of activity accountability and awareness, conflicts over simultaneous access, difficulties controlling access, and collaborative password use. Our work provides insights into the current difficulties people face in workplace collaboration with online account sharing, as a result of inappropriate designs that still assume a single-user model for accounts. We highlight opportunities for CSCW and HCI researchers and designers to better support sharing by multiple people in a more usable and secure way.

Carrier-resolved photo-Hall effect.

The fundamental parameters of majority and minority charge carriers-including their type, density and mobility-govern the performance of semiconductor devices yet can be difficult to measure. Although the Hall measurement technique is currently the standard for extracting the properties of majority carriers, those of minority carriers have typically only been accessible through the application of separate techniques. Here we demonstrate an extension to the classic Hall measurement-a carrier-resolved photo-Hall technique-that enables us to simultaneously obtain the mobility and concentration of both majority and minority carriers, as well as the recombination lifetime, diffusion length and recombination coefficient. This is enabled by advances in a.c.-field Hall measurement using a rotating parallel dipole line system and an equation, ΔμH=d(σ2H)/dσ, which relates the hole-electron Hall mobility difference (ΔμH), the conductivity (σ) and the Hall coefficient (H). We apply this technique to various solar absorbers-including high-performance lead-iodide-based perovskites-and demonstrate simultaneous access to majority and minority carrier parameters and map the results against varying light intensities. This information, which is buried within the photo-Hall measurement1,2, had remained inaccessible since the original discovery of the Hall effect in 18793. The simultaneous measurement of majority and minority carriers should have broad applications, including in photovoltaics and other optoelectronic devices.

Synergistic impacts of agricultural credit and extension on adoption of climate-smart agricultural technologies in southern Africa

Institutional credit and extension services are critical inputs that can reduce scaling challenges in agricultural development interventions if accessed by farmers. Using household level survey data from Zimbabwe and Malawi, this article seeks to contribute to the existing literature by examining impacts of separate and joint access to credit and extension services on climate-smart agricultural (CSA) technologies adoption. Using inverse-probability weighting regression adjustment and propensity score matching this study found out that access to either extension or credit significantly progresses CSA technology adoption. However, access to extension services only proved to be more effective in enhancing CSA technology adoption than access to credit alone. More importantly, results show enhanced collective impact of simultaneous access to credit and extension on CSA technology adoption. Further, joint impacts of credit and extension on adoption were found to be less pronounced in youthful and women farmer groups compared to their old and male farmer group counterparts respectively. Results call for prudent policy and institutional strategies in improving access to credit and extension services in Malawian and Zimbabwean smallholder farming that are mindful of disadvantaged groups such as youth and women farmer groups in order to improve adoption and upscaling of CSA technologies. Possible options include; improving number of extension workers at village level, increasing youth and women extension agent numbers, capacity building of extension personnel and institutions, and increasing financial support to national extension programs.

Theoretical Analysis of Interference Cancellation System Utilizing an Orthogonal Matched Filter and Adaptive Array Antenna for MANET

This study provides a mathematical model and theoretical analysis of an interference cancellation system combining an orthogonal matched filter (OMF) and adaptive array antenna that is called the extended OMF (EOMF). In recent years, an increase in the number of applications of mobile ad hoc networks (MANETs) is expected. To realize a highly reliable MANET, it is essential to introduce a method for cancelling the interference from other nodes. This research focuses on a scheme based on Code Division Multiple Access (CDMA) that enables simultaneous multiple access and low latency communication. However, there are problems with deteriorating performance due to the near–far problem and the increase in the amount of interference as the number of users increases. Additionally, another problem is that the spreading sequence of each user is unknown in a MANET. The OMF is expected to be a solution to these problems. The OMF performs interference cancellation by generating and subtracting a replica of the interference signal that is contained in the received signal. However, the OMF may generate an incorrect replica in the near–far problem. The EOMF compensates for the OMF’s weakness by combining the OMF with an adaptive array antenna. In this research, optimal parameters are derived from mathematical modelling and theoretical analysis of the EOMF. Specifically, the optimal weight vector and the minimum mean squared error that allow the adaptive algorithm to converge are derived and obtained from the numerical results.

Simultaneous access to the low-frequency dynamics and ultraslow kinetics of the thermal expansion behavior of polyurethanes

A long-lasting technological and scientific need exists for more detailed understanding of the dynamics of thermo-mechanical properties of polymers. This article demonstrates how low-frequency dynamics and ultraslow kinetics of thermal expansion of polymers are easily measured by the spectroscopic dilatometry technique called “Temperature Modulated Optical Refractometry”. The influence of molecular packing and dynamics is investigated on the kinetic and dynamic glass transition of three visco-elastic polyurethane networks of different crosslink density. A major observation is the potentially massive difference between kinetic and dynamic thermal expansion coefficients for the vitrifying polyurethane networks at a given temperature. The same holds true for the kinetic and dynamic glass transition temperatures Tg kin and Tg dyn, which are observed to differ by 15 K under given cooling and temperature modulation conditions. The here used cooling procedures show how in general the comparison of the low-frequency dynamics with the kinetics allows for a given material to estimate the dynamic response from the kinetic response, and vice versa. First insights are gained into how far the relaxation dynamics of the polyurethane networks spread over a considerably larger temperature interval than those of a linear chain polymer.

Introducing the Loop for Circuit Access during Extracorporeal Membrane Oxygenation: Feasibility and Safety

In extracorporeal membrane oxygenation (ECMO), blood is drained from the patient, and pumped through a membrane oxygenator/lung (ML) for gas exchange and then back to the patient. For monitoring blood gases, samples may be sampled downstream from the ML. This exposes the patient for embolization risk (air/clot) when the stopcocks are flushed. For safe sampling procedures, the Loop was introduced. It is a constant low-flow arteriovenous shunt (AVS) used preferably in venoarterial ECMO. It is composed of three different length and diameter three-way stopcocks connected to the circuit just downstream the ML with its return upstream the pump. It offers safe arterial blood sampling and a simultaneous access point to the venous side of the circuit. Since its introduction, no patient complications have been reported to be accounted for by the Loop. The Loop is an AVS permitting a safe access point for post membrane blood sampling and for injections in the venous pre-pump limb. It has a low cost and is easy to install and maintain. It may be used in any ECMO configuration.

Multiversion Concurrency Control with the Precedence Graph Generation Algorithm

Simultaneous access of a shared record by multiple transactions leads to conflicts while writing. Such scenario generates the problems like lost update, dirty read, nonrepeatable read etc . In such a case, transaction need to be rolled back to get the system into a consistent state. To handle these conflicts Multiversion Concurrency control (MVCC) is used. MVCC has the ability to avoid the read-write conflicts by performing the read operations using the older version when the write request is in progress. When the multiple write operation concurrently executes then the transaction is aborted or rolled back. To address the problem of rollbacks, a methodology using the Precedence Graph generation based algorithm to reschedule the sequence of the transaction is proposed. In the proposed methodology whenever there is a system failure or network failure the transaction need not be started again, rather it is partially rolled back. The proposed methodology is executed and compared with the other MVCC approached on same set of transactions defined on shared and non shared data items. It is observed that the proposed methodology achieves better execution time as compared to the methods available in the literature

Association of Upper Extremity and Neck Access With Stroke in Endovascular Aortic Repair

Upper extremity and neck access is increasingly being used for complex endovascular aortic repairs. We sought to compare perioperative stroke and other complications of (1) arm/neck with femoral/iliac access (AN) vs femoral/iliac access alone (FI), (2) right- vs left-sided AN, and (3) arm vs neck access sites. Patients entered in the thoracic endovascular aortic repair/complex endovascular aneurysm repair registry in the Vascular Quality Initiative from 2009 to 2018 were analyzed. Patients with a missing access variable were excluded. The primary outcome was perioperative stroke. Secondary outcomes were other postoperative complications and 1-year survival. Kaplan-Meier curves and log-rank test were used for survival analysis. Of 11,774 patients, 9229 met criteria for analysis (2364 AN, 6865 FI). AN patients had a higher rate of smoking history (77.3% vs 72.8%; P < .0001) and prior cerebrovascular events (11.8% vs 9.6%; P = .004). Operative time (250 ± 123 minutes vs 155 ± 102 minutes; P < .0001), contrast material load (136 ± 77 mL vs 105 ± 67 mL; P < .0001), and estimated blood loss (250 mL vs 100 mL; P < .0001) were larger in the AN group indicating these were likely to be more complex cases. Overall, AN had a higher rate of stroke (4.2% vs 2.8%; P = .0005) than FI (Table I). There was no difference in stroke in comparing right and left AN access (4.9% vs 3.8%; P = .28; Table II). Stroke rates were similar between arm, axillary, and carotid access but were significantly higher in patients with multiple simultaneous AN access sites (3.9% vs 4.1% vs 4.4% vs 11.4%; P = .01). AN also had higher rates of puncture site hematoma, access site occlusion, arm ischemia, and in-hospital mortality (Table I). There was no difference in 1-year survival (87.6% vs 85.9%; P = .12). Upper extremity and neck access for complex aortic repairs has a higher risk of stroke compared with femoral and iliac access alone. Right-sided access does not have a higher stroke rate than left-sided access. Neck access does not have a higher stroke rate than arm access, but stroke rate is increased when multiple arm and neck sites are used.Table IPostoperative complications in arm/neck (AN) access compared with femoral/iliac (FI) accessComplicationAN access (n = 2364), No. (%)FI access (n = 6865), No. (%)P valueStroke100 (4.2)191 (2.8).0005Postoperative complications723 (30.6)1512 (22)<.0001Puncture site hematoma104 (4.4)123 (1.8)<.0001Access site occlusion29 (1.2)31 (0.5)<.0001Arm ischemia25 (1.1)34 (0.5).003In-hospital mortality338 (4.9)156 (6.6).002 Open table in a new tab Table IIPostoperative complications comparing right- and left-sided arm/neck (AN) accessComplicationRight (n = 427), No. (%)Left (n = 1826), No. (%)P valueStroke21 (4.9)60 (3.8).28Postoperative complications143 (33.5)544 (29.8).14Puncture site hematoma21 (4.9)77 (4.2).53Access site occlusion5 (1.2)24 (1.3).99Arm ischemia4 (1)21 (1.2).99 Open table in a new tab

A novel application of breadth first algorithm for achieving collision free memory mapping.

We are living in the world of handheld smart devices including smart phones, mini computers, tablets, net-books and others communication devices. The telecommunication standards used in these devices includes error correction codes which are integral part of current and future communication systems. To achieve the higher data rate applications, the turbo and Low Density Parity Check (LDPC) codes are decoded on parallel architecture which in turn raises the memory conflict issue. In order to get the good performance, the simultaneous access to the entire memory bank should be performed without any conflict. In this article we present breadth first technique applied on transportation modeling of the problem for solving the collision issue of Turbo decoders in order to get optimized architecture solution.

A Highly Efficient Heterogeneous Processor for SAR Imaging.

The expansion and improvement of synthetic aperture radar (SAR) technology have greatly enhanced its practicality. SAR imaging requires real-time processing with limited power consumption for large input images. Designing a specific heterogeneous array processor is an effective approach to meet the power consumption constraints and real-time processing requirements of an application system. In this paper, taking a commonly used algorithm for SAR imaging—the chirp scaling algorithm (CSA)—as an example, the characteristics of each calculation stage in the SAR imaging process is analyzed, and the data flow model of SAR imaging is extracted. A heterogeneous array architecture for SAR imaging that effectively supports Fast Fourier Transformation/Inverse Fast Fourier Transform (FFT/IFFT) and phase compensation operations is proposed. First, a heterogeneous array architecture consisting of fixed-point PE units and floating-point FPE units, which are respectively proposed for the FFT/IFFT and phase compensation operations, increasing energy efficiency by 50% compared with the architecture using floating-point units. Second, data cross-placement and simultaneous access strategies are proposed to support the intra-block parallel processing of SAR block imaging, achieving up to 115.2 GOPS throughput. Third, a resource management strategy for heterogeneous computing arrays is designed, which supports the pipeline processing of FFT/IFFT and phase compensation operation, improving PE utilization by a factor of 1.82 and increasing energy efficiency by a factor of 1.5. Implemented in 65-nm technology, the experimental results show that the processor can achieve energy efficiency of up to 254 GOPS/W. The imaging fidelity and accuracy of the proposed processor were verified by evaluating the image quality of the actual scene.

Slicing FIFOs for On-Chip Memory Bandwidth Exhaustion

Within an MPSoC environment, the delivery of data from one computation stage to the next is often the bottleneck of the overall system performance. Especially in high-speed communication where at least two actors (producer and consumer) need access to the same data, the memory interface is usually the limiting factor. Therefore, many solutions like network on chips, clusters of shared memory, memory hierarchy, and so on have been proposed to transfer data from one actor to another. All solutions face the common problem that, at the lowest layer, multiple actors need simultaneous access to a hardware memory block. To avoid using dual port memory macros—which are expensive in terms of chip area—a hardware design is proposed where the communication through First-In-First-Out-Buffers (FIFOs) is transparently sliced to a set of altering memory banks. This allows simultaneous memory accesses to the same FIFO while using only single port memory macros, thus reducing on-chip area and access delay. The proposed FIFO controller balances the load of multiple FIFOs evenly over independent memory regions to maximize system performance.

Role of mesolimbic ghrelin in the acquisition of cocaine reward

The present study examined the ability of ghrelin administration into either the ventral tegmental area (VTA) or nucleus accumbens (NAc) to potentiate cocaine-induced conditioned place preference (CPP). Additionally, we examined the impact of co-injection of the ghrelin 1a antagonist JMV 2959 with ghrelin in order to evaluate the potential attenuation of ghrelin’s effects on cocaine-induced CPP. Adult male Sprague-Dawley rats were allowed simultaneous access to either side of the CPP apparatus to establish baseline chamber preferences. The rats were then restricted to either their non-preferred or preferred side over the course of conditioning which lasted for a total of 8 consecutive days. On days in which rats were restricted to their non-preferred side, systemic cocaine (0.5–5.0 mg/kg IP) followed by central ghrelin (300 pmol), or co-administration of ghrelin (300 pmol) with JMV 2959 (10 μg), was administered either into the VTA or NAc immediately prior to the conditioning period. On alternate days rats were treated with vehicle then placed into what was initially determined to be their preferred side. CPP was calculated as the difference in the percentage of total time spent in the treatment-paired compartment during the post-conditioning session and the pre-conditioning session. Our results indicated that ghrelin potentiated cocaine-induced CPP and that this effect was attenuated by JMV 2959. Overall, these findings provide further evidence that mesolimbic ghrelin signaling is indeed critically involved in mediating the rewarding effects of cocaine.

SmartStreamer: Preference-Aware Multipath Video Streaming Over MPTCP

Simultaneous access to multiple interfaces (e.g., WiFi and cellular networks) can significantly improve the users’ quality of experience (QoE) in video streaming. However, some interfaces could be more expensive to use and less energy efficient. Therefore, in this paper, we propose a preference-aware multipath video streaming algorithm over HTTP using multipath TCP (MPTCP). First, we formulate the quality decisions of the video chunks and the chunk's download policy subject to the chunk's deadlines, the available bandwidth of the different paths, and the link preferences as a non-convex optimization problem. The objective is to optimize a novel QoE metric that maintains a tradeoff between maximizing the quality of every video's chunk and ensuring quality fairness among all chunks for the minimum re-buffering (stall) duration, and without violating the link preference constraint. Second, we develop a polynomial time complexity algorithm to solve the proposed optimization problem, and provide guarantees for the proposed algorithm. We further propose a sliding window based online algorithm where several challenges including short bandwidth prediction with prediction errors are addressed. Extensive emulated experiments with real bandwidth traces of public datasets reveal the robustness of our scheme and demonstrate its significant performance improvement compared to the state-of-the-art multi-path streaming algorithms.