225 research outputs found
The Adversarial Noise Threshold for Distributed Protocols
We consider the problem of implementing distributed protocols, despite
adversarial channel errors, on synchronous-messaging networks with arbitrary
topology.
In our first result we show that any -party -round protocol on an
undirected communication network can be compiled into a robust simulation
protocol on a sparse ( edges) subnetwork so that the simulation
tolerates an adversarial error rate of ; the
simulation has a round complexity of , where is the number of edges in . (So the simulation is
work-preserving up to a factor.) The adversary's error rate is within a
constant factor of optimal. Given the error rate, the round complexity blowup
is within a factor of of optimal, where is the edge
connectivity of . We also determine that the maximum tolerable error rate on
directed communication networks is where is the number of
edges in a minimum equivalent digraph.
Next we investigate adversarial per-edge error rates, where the adversary is
given an error budget on each edge of the network. We determine the exact limit
for tolerable per-edge error rates on an arbitrary directed graph. However, the
construction that approaches this limit has exponential round complexity, so we
give another compiler, which transforms -round protocols into
-round simulations, and prove that for polynomial-query black
box compilers, the per-edge error rate tolerated by this last compiler is
within a constant factor of optimal.Comment: 23 pages, 2 figures. Fixes mistake in theorem 6 and various typo
A Wind-powered Rover for a Low-Cost Venus Mission
Venus, with a surface temperature of 450 C and an atmospheric pressure 90 times higher than that of the Earth, is a difficult target for exploration. However, high-temperature electronics and power systems now being developed make it possible that future missions may be able to operate in the Venus environment. Powering such a rover within the scope of a Discovery class mission will be difficult, but harnessing Venus' surface winds provides a possible way to keep a powered rover small and light. This project scopes out the feasibility of a wind-powered rover for Venus surface missions. Two rover concepts, a land-sailing rover and a wind-turbine-powered rover, were considered. The turbine-powered rover design is selected as being a low-risk and low-cost strategy. Turbine detailed analysis and design shows that the turbine can meet mission requirements across the desired range of wind speeds by utilizing three constant voltage generators at fixed gear ratios
Studii asupra influenţei diverselor surse de azot asupra creşterii şi producţiei la diverse soiuri de castraveţi din solarii
This experiment was conducted at Horticulture Research Station(USAMV Bucuresti)during the summer season of the year 2016. Two cucumbers varieties:Ansor F1 and Trilogy F1, planted under 10 micro plastic greenhouses. The fertilizers treatments included: 300 g/m2DIX 10 N (D); 50 and100 g/m2NovaTec (N1, N2) ;200 g/m2Orgevit(O) and unfertilized control (CA,CT). Results indicated that, there are significant differences among treatments but it was observed that for all characters studied, there is an increase with significantly difference with an increase in N level. Generally, all N fertilizer treatments (organic and Inorganic) increased thesoil (N-NH4, N-NO3, P-PO4, K) levels in soil . Results showed Ansor F1 fertilized with DIX 10 N(AD) and (Ansor F1 and Trilogy F1) with NovaTec 100 g/m2(AN2) and(TN2) gave the strongly positive effect in plant length , plant androot dry matter %. The highest content of pigments was found in Ansor F1 fertilized with DIX 10 N(AD), NovaTec 100 g/m2(AN2) and Trilogy with DIX 10 N(TD). Also observed a significant increasing in leaf content of N-NO3 representedby inorganic fertilizer treatments while the highest content of P-PO4 represented by TN2 and TO (657.86 and728.93 ppm) respectively). It is clearly showed the highest K content effected strongly with the increase of inorganic fertilizers recorded with AN2 and TN2(4513 and 4640 ppm). Results showed that all inorganic treatments gave over the normal and healthy concentration of N-NO2and K in fruits. All treatments had strongly effect with fruit length but the greatest diameter recorded with TN1 and TN2. The best yield results were recorded by Trilogy F1 fertilized with DIX 10 N(TD)and Orgevit(TO)followed by Ansor F1 with Orgevit(AO) treatment,which were obtained on the plant4.10 Kg, 4.04 Kg and 4.05Kg, respectively.There are significant variations between varieties regarding CO2concentration inresponse to the different commercial fertilizers. The highest values was observed to control CA and CT (1449.97 and 1516.76 ppm). All treatments showed significant increase in O2comparing with control variants
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A framework for industrial systems modeling and simulation
To successfully compete in a global market, manufacturing production systems are being forced to reduce time to market and to provide improved responsiveness to changes in market conditions. The organizations that comprise the business links in the production system must constantly make tradeoffs between time and cost in order to achieve a competitive but quick response to consumer demand. Due to the inherent uncertainty of consumer demand, these tradeoffs are, by definition, made with incomplete information and can incur significant financial and competitive risk to the organization. Partnerships between organizations are a mechanism for increasing the information in the decision making process by combining information from the two partners. Partnerships are inherently difficult to implement due to trust issues. A mechanism for investigating and validating the mutual benefit to partnering would be useful in designing and implementing partnerships. This paper describes the development of a software framework for industrial systems modeling and simulation. The framework provides a mechanism for investigating changes to industrial systems in a manner which minimizes the effort and computational power needed to develop focused simulations. The architecture and it`s component parts are described
An investigation of the impact of young children's self-knowledge of trustworthiness on school adjustment: a test of the realistic self-knowledge and positive illusion models
The study aimed to examine the relationship between self-knowledge of trustworthiness and young children’s school adjustment. One hundred and seventy-three (84 male and 89 female) children from school years 1 and 2 in the United Kingdom (mean age 6 years 2 months) were tested twice over one year. Children’s trustworthiness was assessed using: (a) self-report at Time 1 and Time 2, (b) peers’ reports at Time 1 and Time 2, and (c) teacher-reports at Time 2. School adjustment was assessed by child-rated school-liking and the Short-Form Teacher Rating Scale of School Adjustment. Longitudinal quadratic relationships were found between school adjustment and children’s self-knowledge, using peer-reported trustworthiness as a reference: more accurate self-knowledge of trustworthiness predicted increases in school adjustment. Comparable concurrent quadratic relationships were found between teacher-rated school adjustment and children’s self-knowledge, using teacher-reported trustworthiness as a reference, at Time 2. The findings support the conclusion that young children’s psychosocial adjustment is best accounted for by the realistic self-knowledge model (Colvin & Block, 1994)
Differential family and peer environmental factors are related to severity and comorbidity in childresn with ADHD
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70260.pdf (publisher's version ) (Closed access)Behavioral genetic studies imply that salient environmental influences operate within families, making siblings in a family different rather than similar. This study is the first one to examine differential sibling experiences (as measured with the Sibling Inventory of Differential Experience) and its effect on behavioral outcomes within ADHD families. Subjects were 45 Dutch ADHD probands and their unaffected siblings (n = 45) aged 10-18 years. ADHD probands and their unaffected siblings reported differences in sibling interaction, parental treatment, and peer characteristics. These nonshared environmental influences were related to both the severity of ADHD symptoms as well as to comorbid problem behaviors. These findings suggest that environmental influences that operate within ADHD families appear relevant to the severity of problem behaviors of ADHD children and their siblings
Reward and Punishment Sensitivity in Children with ADHD: Validating the Sensitivity to Punishment and Sensitivity to Reward Questionnaire for Children (SPSRQ-C)
This study validates the Sensitivity to Punishment and Sensitivity to Reward Questionnaire for children (SPSRQ-C), using a Dutch sample of 1234 children between 6–13 years old. Factor analysis determined that a 4-factor and a 5-factor solution were best fitting, explaining 41% and 50% of the variance respectively. The 4-factor model was highly similar to the original SPSRQ factors found in adults (Punishment Sensitivity, Reward Responsivity, Impulsivity/Fun-Seeking, and Drive). The 5-factor model was similar to the 4-factor model, with the exception of a subdivision of the Punishment Sensitivity factor into a factor with ‘social-fear’ items and a factor with ‘anxiety’ items. To determine external validity, scores of three groups of children with attention deficit hyperactivity disorder (ADHD) were compared on the EFA models: ADHD-only (n = 34), ADHD and autism spectrum disorder (ADHD+ASD; n = 22), ADHD and oppositional defiant disorder (ADHD+ODD; n = 22). All ADHD groups scored higher than typical controls on Reward Responsivity and on the ‘anxiety’ factor (n = 75). The ADHD-only and ADHD+ODD group scored higher than other groups on Impulsivity/Fun-Seeking and Drive, while the ADHD+ASD group scored higher on Punishment Sensitivity. The findings emphasize the value of the SPSRQ-C to quickly and reliably assess a child’s sensitivity to reinforcement, with the aim to provide individually-tailored behavioral interventions that utilize reward and reprimands
Is there a difference between child self-ratings and parent proxy-ratings of the quality of life of children with a diagnosis of Attention Deficit Hyperactivity Disorder (ADHD)? A systematic review of the literature
There are contemporary indicators that parent proxy-ratings and child self-ratings of a child’s quality of life (QoL) are not interchangeable. This review examines dual informant studies to assess parent–child agreement on the QoL of children with attention-deficit/hyperactivity disorder. A systematic search of four major databases (PsycINFO, MEDLINE, EMBASE and Cochrane databases) was completed, and related peer-reviewed journals were hand-searched. Studies which reported quantitative QoL ratings for matched parent and child dyads were screened in accordance with relevant inclusion and exclusion criteria. Key findings were extracted from thirteen relevant studies, which were rated for conformity to the recommendations of an adapted version of the STROBE statement guidelines for observational studies. In the majority of studies reviewed, children rated their QoL more highly than their parents. There was some evidence for greater agreement on the physical health domain than psychosocial domains
Tracing Changes in Families Who Participated in the Home-Start Parenting Program: Parental Sense of Competence as Mechanism of Change
The present study aimed to (1) determine the long-term effectiveness of Home-Start, a preventive parenting program, and (2) test the hypothesis that changes in maternal sense of competence mediate the program’s effects. Participants were 124 mothers (n = 66 intervention, n = 58 comparison). Four assessments took place during a 1-year period. Latent growth modeling showed that Home-Start enhanced growth in maternal sense of competence and supportive parenting, and led to a decrease in the use of inept discipline. Results of mediational and cross-lagged analyses were consistent with the hypothesized model: Participation in Home-Start was related to the changes in maternal sense of competence, which in turn predicted changes in parenting. The results affirm the importance of directly targeting parental sense of competence in the context of prevention work with parents
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