3,989 research outputs found

    Post-silicon failing-test generation through evolutionary computation

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    The incessant progress in manufacturing technology is posing new challenges to microprocessor designers. Several activities that were originally supposed to be part of the pre-silicon design phase are migrating after tape-out, when the first silicon prototypes are available. The paper describes a post-silicon methodology for devising functional failing tests. Therefore, suited to be exploited by microprocessor producer to detect, analyze and debug speed paths during verification, speed-stepping, or other critical activities. The proposed methodology is based on an evolutionary algorithm and exploits a versatile toolkit named µGP. The paper describes how to take into account complex hardware characteristics and architectural details of such complex devices. The experimental evaluation clearly demonstrates the potential of this line of researc

    Group evolution: Emerging synergy through a coordinated effort

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    Abstract-A huge number of optimization problems, in the CAD area as well as in many other fields, require a solution composed by a set of structurally homogeneous elements. Each element tackles a subset of the original task, and they cumulatively solve the whole problem. Sub-tasks, however, have exactly the same structure, and the splitting is completely arbitrary. Even the number of sub-tasks is not known and cannot be determined a-priori. Individual elements are structurally homogeneous, and their contribution to the main solution can be evaluated separately. We propose an evolutionary algorithm able to optimize groups of individuals for solving this class of problems. An individual of the best solution may be sub-optimal when considered alone, but the set of individuals cumulatively represent the optimal group able to completely solve the whole problem. Results of preliminary experiments show that our algorithm performs better than other techniques commonly applied in the CAD fiel

    Optimal patchings for consecutive ones matrices

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    AbstractWe study a variant of the weighted consecutive ones property problem. Here, a 0/1-matrix is given with a cost associated to each of its entries and one has to find a minimum cost set of zero entries to be turned to ones in order to make the matrix have the consecutive ones property for rows. We investigate polyhedral and combinatorial properties of the problem and we exploit them in a branch-and-cut algorithm. In particular, we devise preprocessing rules and investigate variants of "local cuts". We test the resulting algorithm on a number of instances, and we report on these computational experiments

    UVES observations of QSO 0000-2620: oxygen and zinc abundances in the Damped Ly-alpha galaxy at z_abs=3.3901

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    Observations of the QSO 0000-2620 with UVES spectrograph at the 8.2m ESO KUEYEN telescope are used for abundance analysis of the damped Ly-alpha system at z_{abs}=3.3901. Several Oxygen lines are identified in the Ly_alpha forest and a measure for the oxygen abundance is obtained at [O/H]=-1.85 +/- 0.1 by means of the unsaturated OI 925 A and OI 950 A lines. This represents the most accurate O measurement in a damped Ly_alpha galaxy so far. We have also detected ZnII 2026 A and CrII 2056, 2062 A redshifted at about 8900 A and found abundances [Zn/H] = -2.07 +/- 0.1 and [Cr/H]=-1.99 +/- 0.1. Furthermore, previous measurements of Fe, Si, Ni and N have been refined yielding [Fe/H]=-2.04 +/- 0.1, [Si/H]=-1.90 +/- 0.1, [Ni/H]=-2.27 +/- 0.1, and [N/H]=-2.68 +/- 0.1. The abundance of the non-refractory element zinc is the lowest among the damped Ly-alpha systems showing that the associated intervening galaxy is indeed in the early stages of its chemical evolution. The fact that the Zn abundance is identical to that of the refractory elements Fe and Cr suggests that dust grains have not formed yet. In this Damped Ly-alpha system the observed [O,S,Si/Zn,Fe,Cr] ratios, in whatever combination are taken, are close to solar (i.e 0.1-0.2 dex) and do not show the [alpha-element/Fe] enhancement observed in Milky Way stars of comparable metallicity. The observed behavior supports a galaxy evolution model characterized by either episodic or low star formation rate rather than a Milky-Way-type evolutionary model.Comment: Accepted by Ap

    Laryngeal mask perforation: complication of jugular vein cannulation in a newborn

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    This case report describes the perforation of a laryngeal mask during central venous cannulation of the internal jugular vein in a 2000 g, formerly preterm infant. The procedure was undertaken with the patient under general anaesthesia with a laryngeal mask and spontaneous breathing. As a result of the infant's clinical status, multiple needle insertions were required to obtain venous access. The needle was inadvertently advanced to the retropharynx and perforated the air-filled part of the laryngeal mask. Ventilation parameters remained stable. The laryngeal mask causes anatomical alterations of cervical structures in the newborn and therefore its use for the airway management during jugular vein cannulation appears to be limite

    INCIDENCE OF AMYOTROPHIC LATERAL SCLEROSIS IN SICILY: A POPULATION BASED STUDY.

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    Our objective was to investigate incidence of amyotrophic lateral sclerosis (ALS) in Sicily, southern Italy, by means of a population based study. We included people with ALS resident in fi ve Sicilian provinces, whose onset occurred in the two-year period 2005 2006 (population at 31 December 2006: 3,481,096 inhabitants). A multisource case-fi nding procedure was adopted and patients were classifi ed as affected by ALS according to revised El Escorial criteria. During the two-year surveillance period, 97 patients meeting eligibility criteria included 57 males (58.8%) and 40 females (41.2%). Crude annual incidence rate was 1.4/100,000 person years (95% CI 1.33 1.47). The incidence rate was higher in males (1.71/100,000; CI 1.61 1.81) than in females (1.11/100,000; CI 1.01 1.21). Standardized incidence rate for the total population in the 45 74-years-old age group was 3.22 (CI 3.11 3.33). Prevalence rate was 6.0/100,000 (CI 5.97 6.03), higher in males (7.1/100,000; CI 7.02 7.18) than females (4.9/100,000; CI 4.86 4.94). In conclusion, ALS rates observed in the present study are higher in males than females, with a peak of incidence at 70 years of age in both genders. These fi ndings are consistent with those of other population based European studie
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