A Gating Charge Transfer Center in Voltage Sensors

Voltage sensors regulate the conformations of voltage-dependent ion channels and enzymes. Their nearly switchlike response as a function of membrane voltage comes from the movement of positively charged amino acids, arginine or lysine, across the membrane field. We used mutations with natural and unnatural amino acids, electrophysiological recordings, and x-ray crystallography to identify a charge transfer center in voltage sensors that facilitates this movement. This center consists of a rigid cyclic "cap" and two negatively charged amino acids to interact with a positive charge. Specific mutations induce a preference for lysine relative to arginine. By placing lysine at specific locations, the voltage sensor can be stabilized in different conformations, which enables a dissection of voltage sensor movements and their relation to ion channel opening

Structural Synthesis for GXW Specifications

We define the GXW fragment of linear temporal logic (LTL) as the basis for synthesizing embedded control software for safety-critical applications. Since GXW includes the use of a weak-until operator we are able to specify a number of diverse programmable logic control (PLC) problems, which we have compiled from industrial training sets. For GXW controller specifications, we develop a novel approach for synthesizing a set of synchronously communicating actor-based controllers. This synthesis algorithm proceeds by means of recursing over the structure of GXW specifications, and generates a set of dedicated and synchronously communicating sub-controllers according to the formula structure. In a subsequent step, 2QBF constraint solving identifies and tries to resolve potential conflicts between individual GXW specifications. This structural approach to GXW synthesis supports traceability between requirements and the generated control code as mandated by certification regimes for safety-critical software. Synthesis for GXW specifications is in PSPACE compared to 2EXPTIME-completeness of full-fledged LTL synthesis. Indeed our experimental results suggest that GXW synthesis scales well to industrial-sized control synthesis problems with 20 input and output ports and beyond.Comment: The long (including appendix) version being reviewed by CAV'16 program committee. Compared to the submitted version, one author (out of her wish) is moved to the Acknowledgement. (v2) Corrected typos. (v3) Add an additional remark over environment assumption and easy corner case

China Maritime Report No. 27: PLA Navy Submarine Leadership - Factors Affecting Operational Performance

The way the People’s Liberation Army Navy (PLAN) selects and manages its submarine officers increases the likelihood of human performance errors onboard a PLAN submarine. First, PLAN submarine officers are selected from applicants with among the lowest college entrance examinations of any PLA educational institution, suggesting that PLAN submariners are among the service’s least talented officers. Second, the Party Committee system at the apex of decision-making aboard PLAN submarines may be less agile than other approaches to command, at least in certain circumstances. Lastly, while the policy of embarking flotilla leaders senior to the submarine captain may reduce some of the negative effects associated with the first two conditions, it could lead to reduced performance when senior leaders are not present. If external events during wartime stressed these factors, the likelihood of human-induced error events in the PLAN submarine force could increase substantially.https://digital-commons.usnwc.edu/cmsi-maritime-reports/1026/thumbnail.jp

High speed synchrotron X-ray imaging studies of the ultrasound shockwave and enhanced flow during metal solidification processes

The highly dynamic behaviour of ultrasonic bubble implosion in liquid metal, the multiphase liquid metal flow containing bubbles and particles, and the interaction between ultrasonic waves and semisolid phases during solidification of metal were studied in situ using the complementary ultrafast and high speed synchrotron X-ray imaging facilities housed respectively at the Advanced Photon Source, Argonne National Laboratory, US, and Diamond Light Source, UK. Real-time ultrafast X-ray imaging of 135,780 frames per second (fps) revealed that ultrasonic bubble implosion in a liquid Bi-8 wt. %Zn alloy can occur in a single wave period (30 kHz), and the effective region affected by the shockwave at implosion was 3.5 times the original bubble diameter. Furthermore, ultrasound bubbles in liquid metal move faster than the primary particles, and the velocity of bubbles is 70 ~ 100% higher than that of the primary particles present in the same locations close to the sonotrode. Ultrasound waves can very effectively create a strong swirling flow in a semisolid melt in less than one second. The energetic flow can detach solid particles from the liquid-solid interface and redistribute them back into the bulk liquid very effectively

Distinct roles in autophagy and importance in infectivity of the two ATG4 cysteine peptidases of leishmania major

Macroautophagy in Leishmania, which is important for the cellular remodeling required during differentiation, relies upon the hydrolytic activity of two ATG4 cysteine peptidases (ATG4.1 and ATG4.2). We have investigated the individual contributions of each ATG4 to Leishmania major by generating individual gene deletion mutants (Δatg4.1 and Δatg4.2); double mutants could not be generated, indicating that ATG4 activity is required for parasite viability. Both mutants were viable as promastigotes and infected macrophages in vitro and mice, but Δatg4.2 survived poorly irrespective of infection with promastigotes or amastigotes, whereas this was the case only when promastigotes of Δatg4.1 were used. Promastigotes of Δatg4.2 but not Δatg4.1 were more susceptible than wild type promastigotes to starvation and oxidative stresses, which correlated with increased reactive oxygen species levels and oxidatively damaged proteins in the cells as well as impaired mitochondrial function. The antioxidant N-acetylcysteine reversed this phenotype, reducing both basal and induced autophagy and restoring mitochondrial function, indicating a relationship between reactive oxygen species levels and autophagy. Deletion of ATG4.2 had a more dramatic effect upon autophagy than did deletion of ATG4.1. This phenotype is consistent with a reduced efficiency in the autophagic process in Δatg4.2, possibly due to ATG4.2 having a key role in removal of ATG8 from mature autophagosomes and thus facilitating delivery to the lysosomal network. These findings show that there is a level of functional redundancy between the two ATG4s, and that ATG4.2 appears to be the more important. Moreover, the low infectivity of Δatg4.2 demonstrates that autophagy is important for the virulence of the parasite

THE ROLE OF TEAM DEVELOPMENT IN USER-CENTERED DESIGN INTERVENTIONS: A SOCIO-PSYCHOLOGICAL APPROACH

User participation in information systems development (ISD) has long been linked to systems success. Prior research has focused on identifying a range of contingencies such as task complexity, systems complexity, user influence, user-developer communication, and type of involvement etc. However, very little is known about the development and maturation of groups in (ISD) contexts. The purpose of this study is to examine the relationship between user participation and systems success from a developmental perspective. Using group development as a theoretical lens, a descriptive case study of two groups engaged in sequential user-centered design projects was conducted. The results revealed that social and cognitive forces constrained the development of both groups, resulting in a negative impact on the (ISD) outcomes. This study extends the (ISD) literature by proposing a model that links group development and systems success in ISD contexts

Experience is a Good Teacher: Integrating Service and Learning in Information Systems Education

Over the last decade, the incorporation of service-learning into higher education has grown at an astounding rate. Despite the increase, service-learning remains an under-researched and underexplored pedagogical innovation in information systems education. This study investigates the impacts of service-learning on student learning and development outcomes in a juniorlevel systems design course. The results confirmed that service-learning had a positive impact on student learning and development along three dimensions: academic learning, interpersonal development, and personal development. The study concludes with implications for research and practice

The Ambidextrous Pursuit of Strategic Information Technology Alignment and Organizational Agility in the Community Benefit Sector

The information systems literature suggests a positive relationship between strategic information technology alignment and organizational agility, and the implications on performance for organizations operating in turbulent environments. This emerging stream of integrated research has begun to provide key insight on the positive benefits of the ambidextrous pursuit of alignment and agility in for-profit organizations. However, these relationships have been largely unexplored in nonprofit settings. Nonprofit organizations exist to address social, political, economic, and cultural challenges rather than maximizing shareholder wealth. In order to address this void in research, this paper draws on the alignment and agility research in order to examine how one exemplary nonprofit is strategically exploiting its information system resources in order to improve performance and social value creation. This paper concludes with implications for research and practice