1,048 research outputs found

    Measuring the Impact of Adversarial Errors on Packet Scheduling Strategies

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    In this paper we explore the problem of achieving efficient packet transmission over unreliable links with worst case occurrence of errors. In such a setup, even an omniscient offline scheduling strategy cannot achieve stability of the packet queue, nor is it able to use up all the available bandwidth. Hence, an important first step is to identify an appropriate metric for measuring the efficiency of scheduling strategies in such a setting. To this end, we propose a relative throughput metric which corresponds to the long term competitive ratio of the algorithm with respect to the optimal. We then explore the impact of the error detection mechanism and feedback delay on our measure. We compare instantaneous error feedback with deferred error feedback, that requires a faulty packet to be fully received in order to detect the error. We propose algorithms for worst-case adversarial and stochastic packet arrival models, and formally analyze their performance. The relative throughput achieved by these algorithms is shown to be close to optimal by deriving lower bounds on the relative throughput of the algorithms and almost matching upper bounds for any algorithm in the considered settings. Our collection of results demonstrate the potential of using instantaneous feedback to improve the performance of communication systems in adverse environments

    Competitive analysis of fundamental scheduling algorithms on a fault-prone machine and the impact of resource augmentation

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    Reliable task execution in machines that are prone to unpredictable crashes and restarts is both challenging and of high importance, but not much work exists on the analysis of such systems. We consider the online version of the problem, with tasks arriving over time at a single machine under worst-case assumptions. We analyze the fault-tolerant properties of four popular scheduling algorithms: Longest In System (LIS), Shortest In System (SIS), Largest Processing Time (LPT) and Shortest Processing Time (SPT).We use three metrics for the evaluation and comparison of their competitive performance, namely, completed load, pending load and latency. We also investigate the effect of resource augmentation in their performance, by increasing the speed of the machine. Hence, we compare the behavior of the algorithms for different speed intervals and show that there is no clear winner with respect to all the three considered metrics. While SPT is the only algorithm that achieves competitiveness on completed load for small speed, LIS is the only one that achieves competitiveness on latency (for large enough speed).pu

    Lampu Pintar Berbasis LED Dengan Multi Sensor

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    In this paper, we propose a LED-based smart lamp prototype that integrated with sensor. The smart lamp use information of people and lighting confirmation, to turn on or turn off the lamp automatically. In addition, the sensor calculates and balances flash and ambient light exposure to decrease the light, so that can make energy efficiently in use. PIR (Passive Infrared Receiver) and Ultrasonic sensor is preferred to detect people condition in one place and LDR (Light Dependent Resistant) is preferred to detect intensity of light. In experimental system of smart lamp obtain good condition where the average of illuminance 257,6 lux. The smart lamp can detect large and small movements caused by human beings and can provide a constant room lighting.keywords: Smart lamp, Presence detection, Ultrasonic Pada tulisan ini, sebuah lampu pintar berbasis LED berbasis integrasi sensor deteksi keberadaan dan sensor deteksi cahaya diusulkan. Sensor digunakan untuk menyalakan atau memadamkan lampu secara otomatis berdasarkan keberadaan orang disekitarnya. Selain itu, lampu pintar juga dapat mengatur tingkat pencahayaan yang dibutuhkan dengan memperhatikan cahaya ambien untuk mencegah terjadinya pencahayaan yang berlebih guna menghindari energi yang terbuang sia-sia. Deteksi keberadaan menggunakan penggabungan dua buah sensor yaitu PIR (Passive Infrared Receiver) dan Ultrasonik, sedangkan deteksi cahaya menggunakan sensor LDR (Light Dependent Resistant). Hasil pengujian mendapatkan sistem lampu penerangan bekerja dengan baik dan dapat memberikan pencahayaan sebesar 257,6 lux. Lampu Pintar tersebut sudah dapat mendeteksi gerakan besar dan kecil yang ditimbulkan oleh manusia dan dapat memberikan pencahayaan ruangan yang konstan

    Nuclear Magnetic Resonance and Molecular Dynamics Simulation of the Interaction between Recognition Protein H7 of the Novel Influenza Virus H7N9 and Glycan Cell Surface Receptors

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    Avian influenza A viruses, which can also propagate between humans, present serious pandemic threats, particularly in Asia. The specificity (selectivity) of interactions between the recognition protein hemagglutinin (HA) of the virus capsid and the glycoconjugates of host cells also contributes to the efficient spread of the virus by aerosol between humans. Some avian origin viruses, such as H1N1 (South Carolina 1918), have improved their selectivity for human receptors by mutation in the HA receptor binding site, to generate pandemic viruses. Molecular details and dynamics of glycan–HA interactions are of interest, both in predicting the pandemic potential of a new emerging strain and in searching for new antiviral drugs. Two complementary techniques, <sup>1</sup>H saturation transfer difference (<sup>1</sup>H STD) nuclear magnetic resonance and molecular dynamics (MD) simulation, were applied to analyze the interaction of the new H7 (A/Anhui/1/13 H7N9) with LSTa [Neu5Ac α(2→3) Gal β(1→3) GlcNAc β(1→3) Gal β(1→4) Glc] and LSTc [Neu5Ac α(2→6) Gal β(1→4) GlcNAc β(1→3) Gal β(1→4) Glc] pentasaccharides, models of avian and human receptor glycans. Their interactions with H7 were analyzed for the first time using <sup>1</sup>H STD and MD, revealing structural and dynamic behavior that could not be obtained from crystal structures, and contributing to glycan–HA specificity. This highlighted aspects that could affect glycan–HA recognition, including the mutation H7 G228S, which increases H2 and H3 specificity for the human receptor. Finally, interactions between LSTc and H7 were compared with those between LSTc and H1 of H1N1 (South Carolina 1918), contributing to our understanding of the recognition ability of HAs

    Intersecting Flavor Branes

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    We consider an instance of the AdS/CFT duality where the bulk theory contains an open string tachyon, and study the instability from the viewpoint of the boundary field theory. We focus on the specific example of the AdS_5 X S^5 background with two probe D7 branes intersecting at general angles. For generic angles supersymmetry is completely broken and there is an open string tachyon between the branes. The field theory action for this system is obtained by coupling to N =4 super Yang-Mills two N =2 hyper multiplets in the fundamental representation of the SU(N) gauge group, but with different choices of embedding of the two N=2 subalgebras into N=4. On the field theory side we find a one-loop Coleman-Weinberg instability in the effective potential for the fundamental scalars. We identify a mesonic operator as the dual of the open string tachyon. By AdS/CFT, we predict the tachyon mass for small 't Hooft coupling (large bulk curvature) and confirm that it violates the AdS stability bound.Comment: 36 page

    A Systematic Review and Analysis of Racial Differences in Treatment for Depression

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    Mental health affects a large proportion of the population across the world. Though many mental health studies exist, they are inconsistent in methodology, conceptualization of terms, and populations studied; as a result, many studies are incomparable with each other. Further, there is arguably too few studies that focus on marginalized or underrepresented populations. The current study aims to address some of this gap in knowledge. The differences in the way depression is diagnosed and treated in various racial and ethnic groups were identified, and the findings of previous studies were analyzed to help improve the way mental health, and specifically depression, is understood for these groups. A systematic review using three databases was conducted and an analysis of 27 studies was ultimately performed. Differences among races and ethnicities regarding treatment, stigma, and variables affecting diagnoses of depression were found. However, more consistent research is needed on this topic to be able to draw stronger conclusions on racial and ethnic differences in depression and treatment

    S-duality and 2d Topological QFT

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    We study the superconformal index for the class of N=2 4d superconformal field theories recently introduced by Gaiotto. These theories are defined by compactifying the (2,0) 6d theory on a Riemann surface with punctures. We interpret the index of the 4d theory associated to an n-punctured Riemann surface as the n-point correlation function of a 2d topological QFT living on the surface. Invariance of the index under generalized S-duality transformations (the mapping class group of the Riemann surface) translates into associativity of the operator algebra of the 2d TQFT. In the A_1 case, for which the 4d SCFTs have a Lagrangian realization, the structure constants and metric of the 2d TQFT can be calculated explicitly in terms of elliptic gamma functions. Associativity then holds thanks to a remarkable symmetry of an elliptic hypergeometric beta integral, proved very recently by van de Bult.Comment: 25 pages, 11 figure

    Determinants Of Foreign Direct Investment In The Manufacturing Industry: A VectorAutoregression Model Approach

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    This paper aimed to identify the factors that affect Foreign Direct Investment (FDI) in the manufacturing industry using a Vector Autoregression (VAR) model. The researcher selected possible economic indicators (Agriculture, Consumer Price Index, Government Expenditure and Unit Labour Cost) through theories and empirical evidences from various researches, covering quarterly period of 2004-2018. The result showed that there is a significant relationship between FDI and the selected economic indicators. It also revealed that shocks agriculture produces a positive impact, as well as government expenditure. However, consumer price index when introduced to shocks showed an immediate negative impact. On the other hand, unit labor cost did not have a significant impact on the foreign investments. The future variability of FDI primarily depends on itself, while the selected indicators affect roughly one-tenth of the future values of FD

    Human (α2→6) and Avian (α2→3) Sialylated Receptors of Influenza A Virus Show Distinct Conformations and Dynamics in Solution

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    Differential interactions between influenza A virus protein hemagglutinin (HA) and α2→3 (avian) or α2→6 (human) sialylated glycan receptors play an important role in governing host specificity and adaptation of the virus. Previous analysis of HA–glycan interactions with trisaccharides showed that, in addition to the terminal sialic acid linkage, the conformation and topology of the glycans, while they are bound to HA, are key factors in regulating these interactions. Here, the solution conformation and dynamics of two representative avian and human glycan pentasaccharide receptors [LSTa, Neu5Ac-α(2→3)-Gal-β(1→3)-GlcNAc-β(1→3)-Gal-β(1→4)-Glc; LSTc, (Neu5Ac-α(2→6)-Gal-β(1→4)-GlcNAc-β(1→3)-Gal-β(1→4)-Glc] have been explored using nuclear magnetic resonance and molecular dynamics simulation. Analyses demonstrate that, in solution, human and avian receptors sample distinct conformations, topologies, and dynamics. These unique features of avian and human receptors in solution could represent distinct molecular characteristics for recognition by HA, thereby providing the HA–glycan interaction specificity in influenza.Finlombardia SPAConselho Nacional de Pesquisas (Brazil)National Institutes of Health (U.S.) (R37 GM057073-13)Singapore. National Research Foundation (Singapore-MIT Alliance for Research and Technology
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